Journal articles on the topic 'Theory of computation not elsewhere classified'

The paper is in three parts. First, we use simple adversary arguments to redevelop and explore some of the no-free-lunch (NFL) theorems and perhaps extend them a little. Second, we clarify the relationship of NFL theorems to algorithm theory and complexity classes such as NP. We claim that NFL is weaker in the sense that the constraints implied by the conjectures of traditional algorithm theory on what an evolutionary algorithm may be expected to accomplish are far more severe than those implied by NFL. Third, we take a brief look at how natural evolution relates to computation and optimization. We suggest that the evolution of complex systems exhibiting high degrees of orderliness is not equivalent in difficulty to optimizing hard (in the complexity sense) problems, and that the optimism in genetic algorithms (GAs) as universal optimizers is not justified by natural evolution. This is an informal tutorial paper—most of the information presented is not formally proven, and is either “common knowledge” or formally proven elsewhere. Some of the claims are intuitions based on experience with algorithms, and in a more formal setting should be classified as conjectures.

We assume the multitape real-time Turing machine as a formal model for parallel real-time computation. Then, we show that, for any positive integer k, there is at least one language Lk which is accepted by a k-tape real-Turing machine, but cannot be accepted by a (k - 1)-tape real-time Turing machine. It follows therefore that the languages accepted by real-time Turing machines form an infinite hierarchy with respect to the number of tapes used. Although this result was previously obtained elsewhere, our proof is considerably shorter, and explicitly builds the languages Lk. The ability of the real-time Turing machine to model practical real-time and/or parallel computations is open to debate. Nevertheless, our result shows how a complexity theory based on a formal model can draw interesting results that are of more general nature than those derived from examples. Thus, we hope to offer a motivation for looking into realistic parallel real-time models of computation.

This article claims that some familiar properties of phrase structure reflect laws of form. It is shown that optimal sequencing of recursive Merge operations so as to dynamically minimize c-command and containment relations in unlabeled branching forms leads to structural correlates of projection. Thus, a tendency for syntactic structures to pattern according to the X-bar schema (or other shapes exhibiting endocentricity and maximality of ‘non-head daughters’) is plausibly an emergent epiphenomenon of efficient computation. The specifier-head-complement configuration of X-bar theory is shown to be intimately connected to the Fibonacci sequence, suggesting connections with similar mathematical properties in optimal arboration and optimal packing elsewhere in nature.

Abstract. Impact from natural hazards is a shared global problem that causes tremendous loss of life and property, economic cost, and damage to the environment. Increasingly, many natural processes show evidence of nonstationary behavior including wind speeds, landslides, wildfires, precipitation, streamflow, sea levels, and earthquakes. Traditional probabilistic analysis of natural hazards based on peaks over threshold (POT) generally assumes stationarity in the magnitudes and arrivals of events, i.e., that the probability of exceedance of some critical event is constant through time. Given increasing evidence of trends in natural hazards, new methods are needed to characterize their probabilistic behavior. The well-developed field of hazard function analysis (HFA) is ideally suited to this problem because its primary goal is to describe changes in the exceedance probability of an event over time. HFA is widely used in medicine, manufacturing, actuarial statistics, reliability engineering, economics, and elsewhere. HFA provides a rich theory to relate the natural hazard event series (X) with its failure time series (T), enabling computation of corresponding average return periods, risk, and reliabilities associated with nonstationary event series. This work investigates the suitability of HFA to characterize nonstationary natural hazards whose POT magnitudes are assumed to follow the widely applied generalized Pareto model. We derive the hazard function for this case and demonstrate how metrics such as reliability and average return period are impacted by nonstationarity and discuss the implications for planning and design. Our theoretical analysis linking hazard random variable X with corresponding failure time series T should have application to a wide class of natural hazards with opportunities for future extensions.

Abstract. Impact from natural hazards is a shared global problem that causes tremendous loss of life and property, economic cost, and damage to the environment. Increasingly, many natural processes show evidence of nonstationary behavior including wind speeds, landslides, wildfires, precipitation, streamflow, sea levels, and earthquakes. Traditional probabilistic analysis of natural hazards based on peaks over threshold (POT) generally assumes stationarity in the magnitudes and arrivals of events, i.e. that the probability of exceedance of some critical event is constant through time. Given increasing evidence of trends in natural hazards, new methods are needed to characterize their probabilistic behavior. The well-developed field of hazard function analysis (HFA) is ideally suited to this problem because its primary goal is to describe changes in the exceedance probability of an event over time. HFA is widely used in medicine, manufacturing, actuarial statistics, reliability engineering, economics, and elsewhere. HFA provides a rich theory to relate the natural hazard event series (X) with its failure time series (T), enabling computation of corresponding average return periods, risk and reliabilities associated with nonstationary event series. This work investigates the suitability of HFA to characterize nonstationary natural hazards whose POT magnitudes are assumed to follow the widely applied Generalized Pareto (GP) model. We derive the hazard function for this case and demonstrate how metrics such as reliability and average return period are impacted by nonstationarity and discuss the implications for planning and design. Our theoretical analysis linking hazard event series X, with corresponding failure time series T, should have application to a wide class of natural hazards with rich opportunities for future extensions.

Viterbi training (VT) provides a fast but inconsistent estimator of hidden Markov models (HMM). The inconsistency is alleviated with a little extra computation when we enable VT to asymptotically fix the true values of the parameters. This relies on infinite Viterbi alignments and associated with them limiting probability distributions. First in a sequel, this article is a proof of concept; it focuses on mixture models, an important but special case of HMM where the limiting distributions can be calculated exactly. A simulated Gaussian mixture shows that our central algorithm (VA1) can significantly improve the accuracy of VT with little extra cost. Next in the sequel, we present elsewhere a theory of the adjusted VT for the general HMMs, where the limiting distributions are more challenging to find. Here, we also present another, more advanced correction to VT and verify its fast convergence and high accuracy; its computational feasibility requires additional investigation.

This article sets its investigative goal on determining the medical knowledge of medieval physicians from 1347-8 to 1351 concerning the causes of plague. As the plague killed a third of Europe’s population, the contemporary witness at the time perceived God as the sender of this plague to punish the human society. However, physicians separated the religious and cultural explanation for the cause of this plague and instead seek the answer to this question elsewhere. Developing on traditional medical knowledges, physicians classified the possible range of the plague’s causes into two areas: universal cause and individual/particular causes. In addition, they also sought to explain the causes by employing the traditional miasma-humoral theory. Unlike the previous ones, however, the plague during 1347-8 to 1351 killed the patients indiscriminately and also incredibly viciously. This phenomenon could not be explained by merely using the traditional medical knowledge and this idiosyncrasy led the physicians employ the poison theory to explain the causes of plague more pragmatically.

To realize cloud manufacturing (CMfg) production in group enterprises, manufacturing resources and modeling technologies of cloud pool were studied. According to the characteristics of group enterprises, manufacturing resources were analyzed and classified into human, equipment, materials, cooperation resources and so on. Then, the realization method which manufacturing resources mapped into virtual resources was researched, and a layer platform for cloud manufacturing was proposed. Taking CNC machine tool as an example, the ontology model was built with Semantic Web and OWL based on ontology theory. Finally, using semantic similarity computation method and case-based reasoning, the virtual resources were intelligent searched and matched so that manufacturing resources can realize unification, sharing and reuse.

In the recent years, Heterogeneous Distributed Networks (HDNs) is a predominant technology implemented to enable various application in different fields like transportation, medicine, war zone, etc. Due to its arbitrary self-organizing nature and temporary topologies in the spatial-temporal region, distributed systems are vulnerable with a few security issues and demands high security countermeasures. Unlike other static networks, the unique characteristics of HDNs demands cutting edge security policies. Numerous cryptographic techniques have been proposed by different researchers to address the security issues in HDNs. These techniques utilize too many resources, resulting in higher network overheads. This being classified under light weight security scheme, the Trust Management System (TMS) tends to be one of the most promising technology, featured with more efficiency in terms of availability, scalability and simplicity. It advocates both the node level validation and data level verification enhancing trust between the attributes. Further, it thwarts a wide range of security attacks by incorporating various statistical techniques and integrated security services. In this paper, we present a literature survey on different TMS that highlights reliable techniques adapted across the entire HDNs. We then comprehensively study the existing distributed trust computations and benchmark them in accordance to their effectiveness. Further, performance analysis is applied on the existing computation techniques and the benchmarked outcome delivered by Recommendation Trust Computations (RTC) is discussed. A Receiver Operating Characteristics (ROC) curve illustrates better accuracy for Recommendation Trust Computations (RTC), in comparison with Direct Trust Computations (DTC) and Hybrid Trust Computations (HTC). Finally, we propose the future directions for research and highlight reliable techniques to build an efficient TMS in HDNs.

This paper provides an investigation on nonlinear dynamic behaviors of the (3+1)-dimensional B-type Kadomtsev—Petviashvili equation, which is used to model the propagation of weakly dispersive waves in a fluid. With the help of the Cole—Hopf transform, the Hirota bilinear equation is established, then the symbolic computation with the ansatz function schemes is employed to search for the diverse exact solutions. Some new results such as the multi-wave complexiton, multi-wave, and periodic lump solutions are found. Furthermore, the abundant traveling wave solutions such as the dark wave, bright-dark wave, and singular periodic wave solutions are also constructed by applying the sub-equation method. Finally, the nonlinear dynamic behaviors of the solutions are presented through the 3-D plots, 2-D contours, and 2-D curves and their corresponding physical characteristics are also elaborated. To our knowledge, the obtained solutions in this work are all new, which are not reported elsewhere. The methods applied in this study can be used to investigate the other PDEs arising in physics.

We compute by a purely local method the (elliptic) θ-twisted character χπY of the representation πY = I(3, 1)(13 × χY) of G = GL (4, F), where F is a p-adic field, p ≠ 2, and Y is an unramified quadratic extension of F; χY is the nontrivial character of F×/NY/FY×. The representation πY is normalizedly induced from [Formula: see text], mi ∈ GL (i, F), on the maximal parabolic subgroup of type (3, 1); θ is the "transpose-inverse" involution of G. We show that the twisted character χπY of πY is an unstable function: its value at a twisted regular elliptic conjugacy class with norm in CY = CY(F)="( GL (2, Y)/F×)F" is minus its value at the other class within the twisted stable conjugacy class. It is 0 at the classes without norm in CY. Moreover πY is the endoscopic lift of the trivial representation of CY. We deal only with unramified Y/F, as globally this case occurs almost everywhere. The case of ramified Y/F would require another paper. Our CY = "( R Y/F GL (2)/ GL (1))F" has Y-points CY(Y) = {(g, g′) ∈ GL (2, Y) × GL (2, Y); det (g) = det (g′)}/Y× (Y× embeds diagonally); σ(≠ 1) in Gal (Y/F) acts by σ(g, g′) = (σg′, σg). It is a θ-twisted elliptic endoscopic group of GL(4). Naturally this computation plays a role in the theory of lifting of CY and GSp(2) to GL(4) using the trace formula, to be discussed elsewhere. Our work extends — to the context of nontrivial central characters — the work of [7], where representations of PGL (4, F) are studied. In [7] we develop a 4-dimensional analogue of the model of the small representation of PGL (3, F) introduced by the first author and Kazhdan in [5] in a 3-dimensional case, and we extend the local method of computation introduced in [6]. As in [7] we use here the classification of twisted (stable) regular conjugacy classes in GL (4, F) of [4], motivated by Weissauer [13].

This research is based on the project investigation and repeated discussion. The British standard BS7910 was the basic theory, and accordingly carried out the experiment, the computation of the stress parameter and an expert system was developed. In this research, the test materials were gathered from project location, and uniaxial tension test, fracture toughness test are made. Then a material parameter database was established; in the research process, the FEA models of typical power plant pressure vessel were established and the stress parameters were gained through simulation method, and a classified stress database was established. The expert system is an effective assistance method for the safety assessment of the flaws, and it may help the ordinary engineers and technicians to grasp the complex assessment process.

We study a class of lattice field theories in two dimensions that includes Yang–Mills and generalized Yang–Mills theories as particular examples. Given a two-dimensional orientable surface of genus g, the partition function Z is defined for a triangulation consisting of n triangles of size ∊. The reason these models are called quasitopological is that Z depends on g, n and ∊ but not on the details of the triangulation. They are also soluble in the sense that the computation of their partition functions for a two-dimensional lattice can be reduced to a soluble one-dimensional problem. We show that the continuum limit is well defined if the model approaches a topological field theory in the zero area limit, i.e. ∊→0 with finite n. We also show that the universality classes of such quasitopological lattice field theories can be easily classified.

A controller design method for Petri net with uncontrollable and unobservable transitions that enforces the conjunction of a set of linear inequalities on the Parikh vector is proposed. The method is based on the theory that each place can be described with a Parikh vector inequality. Constraints are classified into admissible and inadmissible constraints. An inadmissible constraint cannot be directly enforced on a plant because of the uncontrollability or unobservability of certain transitions. Construct the controller though transforming the inadmissible constraint into admissible one. The method eases the design of controller, because it is based on part net design, and it only considers the direct or indirect transitions related to the constraints. So the computation required to find the Petri net controller is quite simple. Finally, the method is proved to be simple and efficient through one example.

This survey presents the broad range of research on using wavelets in the analysis and design of dynamic systems. Though wavelets have been used with all types of systems, the major focus of this survey is mechanical and electromechanical systems in addition to their controls. However, the techniques presented can be applied to any category of dynamic systems such as economic, biological, and social systems. Wavelets can be classified into three different types: orthogonal, biorthogonal, and pseudo, all of which are employed in dynamic systems engineering. Wavelets-based methods for dynamic systems applications can be divided into vibrations analysis and systems and control analysis. Wavelets applications in vibrations extend to oscillatory response solutions and vibrations-based systems identification. Also, their applications in systems and control extend to time–frequency representation and modeling, nonlinear systems linearization and model reduction, and control design and control law computation. There are serious efforts within systems and control theory to establish time–frequency and wavelets-based Frequency Response Functions (FRFs) parallel to the Fourier-based FRFs, which will pave the road for time-varying FRFs. Moreover, the natural similarity of wavelets to the representation of neural networks allows them to slip into neural-networks-based and fuzzy-neural-networks-based controllers. Additionally, wavelets have been considered for applications in feedforward and feedback control loops for computation, analysis, and synthesis of control laws.

A recent discovery in computer and software sciences is that information in general is a deterministic abstract quantity rather than a probability-based property of the nature. Information is a general form of abstract objects represented by symbolical, mathematical, communication, computing, and cognitive systems. Therefore, information science is one of the contemporary scientific disciplines collectively known as abstract sciences such as system, information, cybernetics, cognition, knowledge, and intelligence sciences. This paper presents the cognitive foundations, mathematical models, and formal properties of information towards an extended theory of information science. From this point of view, information is classified into the categories of classic, computational, and cognitive information in the contexts of communication, computation, and cognition, respectively. Based on the three generations of information theories, a coherent framework of contemporary information is introduced, which reveals the nature of information and the fundamental principles of information science and engineering.

Although the quantity of household water consumption does not account for a huge proportion of the total water consumption amidst socioeconomic development, there has been a steadily increasing trend due to population growth and improved urbanization standards. As such, mastering the mechanisms of household water demand, scientifically predicting trends of household water demand, and implementing reasonable control measures are key focuses of current urban water management. Based on the categorization and characteristic analysis of household water, this paper used Maslow’s Hierarchy of Needs to establish a level and grade theory of household water demand, whereby household water is classified into three levels (rigid water demand, flexible water demand, and luxury water demand) and three grades (basic water demand, reasonable water demand, and representational water demand). An in-depth analysis was then carried out on the factors that influence the computation of household water demand, whereby equations for different household water categories were established, and computations for different levels of household water were proposed. Finally, observational experiments on household water consumption were designed, and observation and simulation computations were performed on three typical households in order to verify the scientific outcome and rationality of the computation of household water demand. The research findings contribute to the enhancement and development of prediction theories on water demand, and they are of high theoretical and realistic significance in terms of scientifically predicting future household water demand and fine-tuning the management of urban water resources.

We consider computation with real numbers that arise through a process of physical measurement. We have developed a theory in which physical experiments that measure quantities can be used as oracles to algorithms and we have begun to classify the computational power of various forms of experiment using non-uniform complexity classes. Earlier, in Beggs et al. (2014 Reviews of Symbolic Logic7(4) 618–646), we observed that measurement can be viewed as a process of comparing a rational number z – a test quantity – with a real number y – an unknown quantity; each oracle call performs such a comparison. Experiments can then be classified into three categories, that correspond with being able to return test results $$\begin{eqnarray*} z < y\text{ or }z > y\text{ or }\textit{timeout},\\ z < y\text{ or }\textit{timeout},\\ z \neq y\text{ or }\textit{timeout}. \end{eqnarray*} $$ These categories are called two-sided, threshold and vanishing experiments, respectively. The iterative process of comparing generates a real number y. The computational power of two-sided and threshold experiments were analysed in several papers, including Beggs et al. (2008 Proceedings of the Royal Society, Series A (Mathematical, Physical and Engineering Sciences)464 (2098) 2777–2801), Beggs et al. (2009 Proceedings of the Royal Society, Series A (Mathematical, Physical and Engineering Sciences)465 (2105) 1453–1465), Beggs et al. (2013a Unconventional Computation and Natural Computation (UCNC 2013), Springer-Verlag 6–18), Beggs et al. (2010b Mathematical Structures in Computer Science20 (06) 1019–1050) and Beggs et al. (2014 Reviews of Symbolic Logic, 7 (4):618-646). In this paper, we attack the subtle problem of measuring physical quantities that vanish in some experimental conditions (e.g., Brewster's angle in optics). We analyse in detail a simple generic vanishing experiment for measuring mass and develop general techniques based on parallel experiments, statistical analysis and timing notions that enable us to prove lower and upper bounds for its computational power in different variants. We end with a comparison of various results for all three forms of experiments and a suitable postulate for computation involving analogue inputs that breaks the Church–Turing barrier.

Abstract This article extends theoretical details based on a short paper originally submitted to the 2022 EPS conference in plasma physics [1]. The quasilinear theory of resonant transport regimes in a tokamak is developed for the general case of orbits forming various classes separated in phase space by homoclinic orbits with infinite bounce time. Beyond standard orbits (banana and passing orbits) also all types of non-standard orbits (e.g. “potato” orbits) are taken into account. In case of a weak radial electric field, such orbits are usually present only near the magnetic axis. If the radial electric field cannot be treated as weak, there can be arbitrary many classes, located elsewhere. The present approach covers all such cases and is demonstrated on a specific example of a radial electric field profile. The resulting quasilinear kinetic equation is applicable to compute neoclassical toroidal viscous (NTV) torque in a tokamak with non-axisymmetric magnetic field perturbations. A fully non-local approach to NTV computation has been realized in the upgraded version of the code NEO-RT. Based on a generalization of magnetic flux surfaces to drift surfaces, the notion of a local thermodynamic equilibrium is extended for our purpose. We obtain an expression for the integral toroidal torque within a chosen flux surface and dicuss means to compute such integrals taking singularities in bounce and precession frequencies into account.

The solute segregation to grain boundaries may be classified into equilibrium and non-equilibrium segregation. The models and kinetics calculation equations were proved in previous work. However, the computational task for grain-boundary segregation kinetics process is complex and cumbersome as it can involve a vast amount of numerical data. It is therefore necessary to develop an easily usable computational program which can provide the researchers with a powerful tool in grain-boundary segregation kinetics process analysis in addition to having a sound theory. A computational program of non-equilibrium grain-boundary segregation (NGS) kinetics of solute is therefore developed in this paper. It includes programs for critical time calculation, effective time calculation and diffusion coefficients calculation, the program of Auger Electron Spectroscopy test data disposal, the program of curve fitting and the program of NGS kinetics simulation. A simulation example by using the computation program of NGS kinetic equations is in good accordance with the experimental observation of phosphorus in steel 12Cr1MoV. The computational program of NGS is therefore proved to be appropriate and helpful.

One of the important topics in mathematics is matrix theory. There are various types of matrix, one of which is a circulant matrix. Circulant matrix generally fulfill the same operating axioms as square matrix, except that there are some specific properties for the circulant matrix. Every square matrix has a determinant. The concept of determinants is very useful in the development of mathematics and across disciplines. One method of determining the determinant is condensation. The condensation method is classified as a method that is not widely known. The condensation matrix method in determining the determinant was proposed by several scientists, one of which was Charles Lutwidge Dodgson with the Dodgson condensation method. This paper will discuss the Dodgson condensation method in determining the determinant of the circulant matrix. The result of the condensation of the matrix will affect the size of the original matrix as well as new matrix entries. Changes in the circulant matrix after Dodgson's conduction load the Toeplitz matrix, in certain cases, the determinant of the circulant matrix can also be determined by simple mental computation.

It is proposed that proteins/enzymes be classified into two classes according to their essentiality for immediate survival/reproduction and their function in long-term health: that is, survival proteins versus longevity proteins. As proposed by the triage theory, a modest deficiency of one of the nutrients/cofactors triggers a built-in rationing mechanism that favors the proteins needed for immediate survival and reproduction (survival proteins) while sacrificing those needed to protect against future damage (longevity proteins). Impairment of the function of longevity proteins results in an insidious acceleration of the risk of diseases associated with aging. I also propose that nutrients required for the function of longevity proteins constitute a class of vitamins that are here named “longevity vitamins.” I suggest that many such nutrients play a dual role for both survival and longevity. The evidence for classifying taurine as a conditional vitamin, and the following 10 compounds as putative longevity vitamins, is reviewed: the fungal antioxidant ergothioneine; the bacterial metabolites pyrroloquinoline quinone (PQQ) and queuine; and the plant antioxidant carotenoids lutein, zeaxanthin, lycopene, α- and β-carotene, β-cryptoxanthin, and the marine carotenoid astaxanthin. Because nutrient deficiencies are highly prevalent in the United States (and elsewhere), appropriate supplementation and/or an improved diet could reduce much of the consequent risk of chronic disease and premature aging.

Lagrange and Laplace were two of the first members of Bureau des longitudes which, among other tasks, were responsible for the improvement of astronomical tables and the progress of celestial mechanics. Between 1795 and 1850, many improved tables were published under the auspices of Bureau des longitudes: tables of the Sun by Delambre (1806), of the Moon by Burg (1806), Burckhardt (1812) and Damoiseau (1828), of Jupiter, Saturn and Uranus by Bouvard (1808, 1821), of Mercury by Le Verrier (1844), of the satellites of Jupiter by Delambre (1817) and Damoiseau (1836). In his tables, Bouvard showed there was a problem for Uranus. This led to the calculations of the elements of an unknown planet by Le Verrier and Adams and the discovery of Neptune in 1846. Le Verrier's calculations were published in Connaissance des Temps for 1849. In the second half of the XIXth century, two prominent members of Bureau des longitudes, Le Verrier and Delaunay, made major contributions to celestial mechanics by building elaborate theories for the motions of the Sun, the planets and the Moon. Other theories, which improved the above, appeared elsewhere at the end of the century, especially those of Newcomb, Hill and Brown. During the first half of the XXth century, there was a decline of the studies in celestial mechanics which seemed to have reached its limits owing to the difficulties of the computations involved. Yet Sampson's theory of the motion of the satellites of Jupiter and Chazy's first attempts to introduce general relativity into classical celestial mechanics should be quoted. In 1961, thanks to A. Danjon, Bureau des longitudes was reorganized so that its computation service became a research laboratory where, since then, important work in the theories of the planets, the Moon and the satellites has been made.

In longwall mining, the deformation and destruction of overlying strata always lag behind coal extraction. The overlying strata characteristics at the lateral boundary of the stope can be classified into four categories, i.e., Hard-Soft, Soft-Hard, Hard-Hard, and Soft-Soft. In order to analyze the effect of the above four structures, we adopt viscoelastic theory to the finite element method (FEM) and define the point safety factor to evaluate the rock damage. The accuracy of programming is verified through example verification. A modified viscoelastic-plastic FEM model is applied to analyze the performance of four overburden structures. The numerical computation results show the following: From the rupture of overburden rock to its stabilization, the duration time of four typical structures can be sorted as “Soft-Soft < Hard-Soft < Soft-Hard < Hard-Hard”. The fracture direction and dip angle of each structure vary as well. The fracture zone of the H-S structure is inclined toward the goaf, while that of the S-H structure is inclined to the lateral boundary of the stope. The fracture zone of the H-H structure is also inclined toward the lateral boundary, with a greater angle than the S-H structure, while the fracture zone of the S-S structure is inclined to goaf, with a greater angle than the H-S structure.

AbstractPopulation protocols (Angluin et al. in PODC, 2004) are a model of distributed computation in which indistinguishable, finite-state agents interact in pairs to decide if their initial configuration, i.e., the initial number of agents in each state, satisfies a given property. In a seminal paper Angluin et al. classified population protocols according to their communication mechanism, and conducted an exhaustive study of the expressive power of each class, that is, of the properties they can decide (Angluin et al. in Distrib Comput 20(4):279–304, 2007). In this paper we study the correctness problem for population protocols, i.e., whether a given protocol decides a given property. A previous paper (Esparza et al. in Acta Inform 54(2):191–215, 2017) has shown that the problem is decidable for the main population protocol model, but at least as hard as the reachability problem for Petri nets, which has recently been proved to have non-elementary complexity. Motivated by this result, we study the computational complexity of the correctness problem for all other classes introduced by Angluin et al., some of which are less powerful than the main model. Our main results show that for the class of observation models the complexity of the problem is much lower, ranging from $$\varPi _2^p$$ Π 2 p to .

Branching tube flows are examined, for one mother to two, three or more daughter tubes. The case of many daughters (abrupt multi-branching) models blood flow through an arteriovenous malformation in the brain, while that of very few daughters (gradual branching) applies elsewhere in physiology and surgical grafting, as well as other applications including industrial ones. Theory and computation are presented for two- and three-dimensional motions, under the viscous and inviscid effects of small changes in mass flux between the daughter tubes, area expansion and turning of the flow. Specific configurations for which flow solutions are obtained are (a) with two large daughters, (b) with one small daughter/side branch, and (c) with multiple small daughters.The numerous physical mechanisms acting concern overall upstream influence and through-flow, and flow separation and criteria for its avoidance, as well as criteria for the amount of turning and area expansion possible without energy loss and other factors associated with separation, and the role of the branching geometry versus that of the mass-flux distribution in the daughters. In particular, configuration (a) allows substantial separation-free turning and expansion only with certain shaping of the outer wall and an area expansion ratio typically less than 1.2, whereas more daughters involve a balance between geometry and mass flux. In (b), an abrupt pressure jump is induced at the mouth of the small daughter, near which mass-flux effects tend to dominate over geometrical shaping effects. In (c), as the number of daughters increases, the amount of separation-free turning and expansion is found to increase substantially, and the distributed mass-flux influence readily overrides the geometrical influence throughout the branching; there is also an integrated upstream effect of the multi-branching on the incident mother flow even though each daughter flow acts as if independent. Tentative designs based on wall shaping, flux distributions and divider placement are considered for flow improvement/surgery.

Throughout the past decade, vehicular networks have attracted a great deal of interest in various fields. The increasing number of vehicles has led to challenges in traffic regulation. Vehicle-type detection is an important research topic that has found various applications in numerous fields. Its main purpose is to extract the different features of vehicles from videos or pictures captured by traffic surveillance so as to identify the types of vehicles, and then provide reference information for traffic monitoring and control. In this paper, we propose a step-forward vehicle-detection and -classification method using a saliency map and the convolutional neural-network (CNN) technique. Specifically, compressed-sensing (CS) theory is applied to generate the saliency map to label the vehicles in an image, and the CNN scheme is then used to classify them. We applied the concept of the saliency map to search the image for target vehicles: this step is based on the use of the saliency map to minimize redundant areas. CS was used to measure the image of interest and obtain its saliency in the measurement domain. Because the data in the measurement domain are much smaller than those in the pixel domain, saliency maps can be generated at a low computation cost and faster speed. Then, based on the saliency map, we identified the target vehicles and classified them into different types using the CNN. The experimental results show that our method is able to speed up the window-calibrating stages of CNN-based image classification. Moreover, our proposed method has better overall performance in vehicle-type detection compared with other methods. It has very broad prospects for practical applications in vehicular networks.

SUMMARY The elastic moduli estimated through geophysical studies carried out in wells (logging data) differ from those obtained from the triaxial tests conducted in laboratory on the available core samples. Terminologically former and latter are referred to as dynamic and static elastic moduli, respectively. Since the structural characteristics of rocks at the different scales, from micrometre to larger scales (tens of metre), are the controlling parameters of their dynamic and static moduli and their difference at the respective scale, in this study we aim to investigate the influence of the measurable (or quantifiable) parameters of the pore space on these elastic moduli. To do so, 19 dry carbonate samples of different structural characteristics were collected. Their basic petrophysical properties such as porosity and permeability were measured in laboratory. The ultra-sonic tomography was carried out to determine the heterogeneity degree, anisotropy system and average acoustic wave velocities for each core sample. SEM images were analysed to investigate the visual textural properties. The mineralogical composition of these samples was determined by the X-ray diffraction method. Based on the conducted experimental studies and using of the effective medium theory, a unique rock physics model (‘petroelastic model’) was constructed for each core sample. The average (effective) microstructural parameters characterizing the pore space of the studied carbonate samples, along with their elastic moduli were estimated through solving the inverse problem and the measured acoustic wave velocities. A multistage statistical approach, including computation of correlation coefficients, optimized regression analysis, factor analysis and bootstrap resampling, was suggested to investigate the effect of each microstructural parameters on the static and dynamic Young's moduli, ratio of dynamic to static Young's moduli (k-value), dynamic Poisson's ratio and mechanical properties (including unconfined compressive strength and internal friction angle). The obtained results show that the microstructural characteristics have different degrees of influence on the elastic moduli and can be successfully classified based on their physical nature. It was also concluded that the dynamic Poisson's ratio is independent of the studied, in this work, microstructural parameters.

Recent Trends and Future of Fog and Edge Computing, Services, and Enabling Technologies Cloud computing has been established as the most popular as well as suitable computing infrastructure providing on-demand, scalable and pay-as-you-go computing resources and services for the state-of-the-art ICT applications which generate a massive amount of data. Though Cloud is certainly the most fitting solution for most of the applications with respect to processing capability and storage, it may not be so for the real-time applications. The main problem with Cloud is the latency as the Cloud data centres typically are very far from the data sources as well as the data consumers. This latency is ok with the application domains such as enterprise or web applications, but not for the modern Internet of Things (IoT)-based pervasive and ubiquitous application domains such as autonomous vehicle, smart and pervasive healthcare, real-time traffic monitoring, unmanned aerial vehicles, smart building, smart city, smart manufacturing, cognitive IoT, and so on. The prerequisite for these types of application is that the latency between the data generation and consumption should be minimal. For that, the generated data need to be processed locally, instead of sending to the Cloud. This approach is known as Edge computing where the data processing is done at the network edge in the edge devices such as set-top boxes, access points, routers, switches, base stations etc. which are typically located at the edge of the network. These devices are increasingly being incorporated with significant computing and storage capacity to cater to the need for local Big Data processing. The enabling of Edge computing can be attributed to the Emerging network technologies, such as 4G and cognitive radios, high-speed wireless networks, and energy-efficient sophisticated sensors. Different Edge computing architectures are proposed (e.g., Fog computing, mobile edge computing (MEC), cloudlets, etc.). All of these enable the IoT and sensor data to be processed closer to the data sources. But, among them, Fog computing, a Cisco initiative, has attracted the most attention of people from both academia and corporate and has been emerged as a new computing-infrastructural paradigm in recent years. Though Fog computing has been proposed as a different computing architecture than Cloud, it is not meant to replace the Cloud. Rather, Fog computing extends the Cloud services to network edges for providing computation, networking, and storage services between end devices and data centres. Ideally, Fog nodes (edge devices) are supposed to pre-process the data, serve the need of the associated applications preliminarily, and forward the data to the Cloud if the data are needed to be stored and analysed further. Fog computing enhances the benefits from smart devices operational not only in network perimeter but also under cloud servers. Fog-enabled services can be deployed anywhere in the network, and with these services provisioning and management, huge potential can be visualized to enhance intelligence within computing networks to realize context-awareness, high response time, and network traffic offloading. Several possibilities of Fog computing are already established. For example, sustainable smart cities, smart grid, smart logistics, environment monitoring, video surveillance, etc. To design and implementation of Fog computing systems, various challenges concerning system design and implementation, computing and communication, system architecture and integration, application-based implementations, fault tolerance, designing efficient algorithms and protocols, availability and reliability, security and privacy, energy-efficiency and sustainability, etc. are needed to be addressed. Also, to make Fog compatible with Cloud several factors such as Fog and Cloud system integration, service collaboration between Fog and Cloud, workload balance between Fog and Cloud, and so on need to be taken care of. It is our great privilege to present before you Volume 20, Issue 2 of the Scalable Computing: Practice and Experience. We had received 20 Research Papers and out of which 14 Papers are selected for Publication. The aim of this special issue is to highlight Recent Trends and Future of Fog and Edge Computing, Services and Enabling technologies. The special issue will present new dimensions of research to researchers and industry professionals with regard to Fog Computing, Cloud Computing and Edge Computing. Sujata Dash et al. contributed a paper titled “Edge and Fog Computing in Healthcare- A Review” in which an in-depth review of fog and mist computing in the area of health care informatics is analysed, classified and discussed. The review presented in this paper is primarily focussed on three main aspects: The requirements of IoT based healthcare model and the description of services provided by fog computing to address then. The architecture of an IoT based health care system embedding fog computing layer and implementation of fog computing layer services along with performance and advantages. In addition to this, the researchers have highlighted the trade-off when allocating computational task to the level of network and also elaborated various challenges and security issues of fog and edge computing related to healthcare applications. Parminder Singh et al. in the paper titled “Triangulation Resource Provisioning for Web Applications in Cloud Computing: A Profit-Aware” proposed a novel triangulation resource provisioning (TRP) technique with a profit-aware surplus VM selection policy to ensure fair resource utilization in hourly billing cycle while giving the quality of service to end-users. The proposed technique use time series workload forecasting, CPU utilization and response time in the analysis phase. The proposed technique is tested using CloudSim simulator and R language is used to implement prediction model on ClarkNet weblog. The proposed approach is compared with two baseline approaches i.e. Cost-aware (LRM) and (ARMA). The response time, CPU utilization and predicted request are applied in the analysis and planning phase for scaling decisions. The profit-aware surplus VM selection policy used in the execution phase for select the appropriate VM for scale-down. The result shows that the proposed model for web applications provides fair utilization of resources with minimum cost, thus provides maximum profit to application provider and QoE to the end users. Akshi kumar and Abhilasha Sharma in the paper titled “Ontology driven Social Big Data Analytics for Fog enabled Sentic-Social Governance” utilized a semantic knowledge model for investigating public opinion towards adaption of fog enabled services for governance and comprehending the significance of two s-components (sentic and social) in aforesaid structure that specifically visualize fog enabled Sentic-Social Governance. The results using conventional TF-IDF (Term Frequency-Inverse Document Frequency) feature extraction are empirically compared with ontology driven TF-IDF feature extraction to find the best opinion mining model with optimal accuracy. The results concluded that implementation of ontology driven opinion mining for feature extraction in polarity classification outperforms the traditional TF-IDF method validated over baseline supervised learning algorithms with an average of 7.3% improvement in accuracy and approximately 38% reduction in features has been reported. Avinash Kaur and Pooja Gupta in the paper titled “Hybrid Balanced Task Clustering Algorithm for Scientific workflows in Cloud Computing” proposed novel hybrid balanced task clustering algorithm using the parameter of impact factor of workflows along with the structure of workflow and using this technique, tasks can be considered for clustering either vertically or horizontally based on value of impact factor. The testing of the algorithm proposed is done on Workflowsim- an extension of CloudSim and DAG model of workflow was executed. The Algorithm was tested on variables- Execution time of workflow and Performance Gain and compared with four clustering methods: Horizontal Runtime Balancing (HRB), Horizontal Clustering (HC), Horizontal Distance Balancing (HDB) and Horizontal Impact Factor Balancing (HIFB) and results stated that proposed algorithm is almost 5-10% better in makespan time of workflow depending on the workflow used. Pijush Kanti Dutta Pramanik et al. in the paper titled “Green and Sustainable High-Performance Computing with Smartphone Crowd Computing: Benefits, Enablers and Challenges” presented a comprehensive statistical survey of the various commercial CPUs, GPUs, SoCs for smartphones confirming the capability of the SCC as an alternative to HPC. An exhaustive survey is presented on the present and optimistic future of the continuous improvement and research on different aspects of smartphone battery and other alternative power sources which will allow users to use their smartphones for SCC without worrying about the battery running out. Dhanapal and P. Nithyanandam in the paper titled “The Slow HTTP Distributed Denial of Service (DDOS) Attack Detection in Cloud” proposed a novel method to detect slow HTTP DDoS attacks in cloud to overcome the issue of consuming all available server resources and making it unavailable to the real users. The proposed method is implemented using OpenStack cloud platform with slowHTTPTest tool. The results stated that proposed technique detects the attack in efficient manner. Mandeep Kaur and Rajni Mohana in the paper titled “Static Load Balancing Technique for Geographically partitioned Public Cloud” proposed a novel approach focused upon load balancing in the partitioned public cloud by combining centralized and decentralized approaches, assuming the presence of fog layer. A load balancer entity is used for decentralized load balancing at partitions and a controller entity is used for centralized level to balance the overall load at various partitions. Results are compared with First Come First Serve (FCFS) and Shortest Job First (SJF) algorithms. In this work, the researchers compared the Waiting Time, Finish Time and Actual Run Time of tasks using these algorithms. To reduce the number of unhandled jobs, a new load state is introduced which checks load beyond conventional load states. Major objective of this approach is to reduce the need of runtime virtual machine migration and to reduce the wastage of resources, which may be occurring due to predefined values of threshold. Mukta and Neeraj Gupta in the paper titled “Analytical Available Bandwidth Estimation in Wireless Ad-Hoc Networks considering Mobility in 3-Dimensional Space” proposes an analytical approach named Analytical Available Bandwidth Estimation Including Mobility (AABWM) to estimate ABW on a link. The major contributions of the proposed work are: i) it uses mathematical models based on renewal theory to calculate the collision probability of data packets which makes the process simple and accurate, ii) consideration of mobility under 3-D space to predict the link failure and provides an accurate admission control. To test the proposed technique, the researcher used NS-2 simulator to compare the proposed technique i.e. AABWM with AODV, ABE, IAB and IBEM on throughput, Packet loss ratio and Data delivery. Results stated that AABWM performs better as compared to other approaches. R.Sridharan and S. Domnic in the paper titled “Placement Strategy for Intercommunicating Tasks of an Elastic Request in Fog-Cloud Environment” proposed a novel heuristic IcAPER,(Inter-communication Aware Placement for Elastic Requests) algorithm. The proposed algorithm uses the network neighborhood machine for placement, once current resource is fully utilized by the application. The performance IcAPER algorithm is compared with First Come First Serve (FCFS), Random and First Fit Decreasing (FFD) algorithms for the parameters (a) resource utilization (b) resource fragmentation and (c) Number of requests having intercommunicating tasks placed on to same PM using CloudSim simulator. Simulation results shows IcAPER maps 34% more tasks on to the same PM and also increase the resource utilization by 13% while decreasing the resource fragmentation by 37.8% when compared to other algorithms. Velliangiri S. et al. in the paper titled “Trust factor based key distribution protocol in Hybrid Cloud Environment” proposed a novel security protocol comprising of two stages: first stage, Group Creation using the trust factor and develop key distribution security protocol. It performs the communication process among the virtual machine communication nodes. Creating several groups based on the cluster and trust factors methods. The second stage, the ECC (Elliptic Curve Cryptography) based distribution security protocol is developed. The performance of the Trust Factor Based Key Distribution protocol is compared with the existing ECC and Diffie Hellman key exchange technique. The results state that the proposed security protocol has more secure communication and better resource utilization than the ECC and Diffie Hellman key exchange technique in the Hybrid cloud. Vivek kumar prasad et al. in the paper titled “Influence of Monitoring: Fog and Edge Computing” discussed various techniques involved for monitoring for edge and fog computing and its advantages in addition to a case study based on Healthcare monitoring system. Avinash Kaur et al. elaborated a comprehensive view of existing data placement schemes proposed in literature for cloud computing. Further, it classified data placement schemes based on their assess capabilities and objectives and in addition to this comparison of data placement schemes. Parminder Singh et al. presented a comprehensive review of Auto-Scaling techniques of web applications in cloud computing. The complete taxonomy of the reviewed articles is done on varied parameters like auto-scaling, approach, resources, monitoring tool, experiment, workload and metric, etc. Simar Preet Singh et al. in the paper titled “Dynamic Task Scheduling using Balanced VM Allocation Policy for Fog Computing Platform” proposed a novel scheme to improve the user contentment by improving the cost to operation length ratio, reducing the customer churn, and boosting the operational revenue. The proposed scheme is learnt to reduce the queue size by effectively allocating the resources, which resulted in the form of quicker completion of user workflows. The proposed method results are evaluated against the state-of-the-art scene with non-power aware based task scheduling mechanism. The results were analyzed using parameters-- energy, SLA infringement and workflow execution delay. The performance of the proposed schema was analyzed in various experiments particularly designed to analyze various aspects for workflow processing on given fog resources. The LRR (35.85 kWh) model has been found most efficient on the basis of average energy consumption in comparison to the LR (34.86 kWh), THR (41.97 kWh), MAD (45.73 kWh) and IQR (47.87 kWh). The LRR model has been also observed as the leader when compared on the basis of number of VM migrations. The LRR (2520 VMs) has been observed as best contender on the basis of mean of number of VM migrations in comparison with LR (2555 VMs), THR (4769 VMs), MAD (5138 VMs) and IQR (5352 VMs).

AbstractThe tenfold way provides a strong organizing principle for invertible topological phases of matter. Mathematically, it is intimately connected with K-theory via the fact that there exist exactly ten Morita classes of simple real superalgebras. This connection is physically unsurprising, since weakly interacting topological phases are classified by K-theory. We argue that when strong interactions are present, care has to be taken when formulating the exact ten symmetry groups present in the tenfold way table. We study this phenomenon in the example of class D by providing two possible mathematical interpretations of a class D symmetry. These two interpretations of class D result in Morita equivalent but different symmetry groups. As K-theory cannot distinguish Morita-equivalent protecting symmetry groups, the two approaches lead to the same classification of topological phases on the weakly interacting side. However, we show that these two different symmetry groups yield different interacting classifications in spacetime dimension 2+1. We use the approach to interacting topological phases using bordism groups, reducing the relevant classification problem to a spectral sequence computation.

Background: Brugada syndrome (BrS) risk stratification in asymptomatic subjects and its underlying pathophysiological dynamics is complex. Purpose: This study aims to analyze, from alternative standpoints, superficial 12-lead ECG V2 repolarization patterns (repol.). This method diverges from ECG pattern characterization (patterns, angles, shapes, intervals, waves); it rather exploits nonlinear dynamics and stability of ECG repol. to assess stability driving cardiac dynamics: basal, after flecainide, during RF ablation, after 2nd flecainide test and post procedure. Target: to lower the number of invasive electrophysiology studies, furthering knowledge and applications of control-and-stability-theory applied to ECG. Methods: A stability control closed loop system has been designed to model electrophysiology dynamics of cardiac conduction: ECG segments being the input-output of the system. (Figure). A sequence of V2 repol. have been scanned, digitized and quantitatively processed yielding stability parameters (poles in S-plane). Scanning by Digitizeit - Digital River GmbH. S-plane computation by Microsoft Office, Wolfram Demonstrations Project & Contributors, https://demonstrations.wolfram.com Results: Figure. Conclusions: Based on our data, 1) 12-lead-ECG repol. are associated with increasing stability (parameter values b), denoting underlying nonlinear dynamics, trending to incremental stability from basal to end of procedure.2) The incremental stability associated with all the process phases, from basal to end of procedure, indicates a potential use of this methodology to BrS risk stratification. Unstable repol. may be classified as high VT risk. In conclusion, furthering control-and-stability-theory applied to 12-lead ECGs aims to deeper comprehension of physiological and pathological substrates of malignant arrhythmias, and to focus on noninvasive risk stratification strategies for ICD implantation indication in BrS.

AbstractIndia ranks the second in the world in terms of its sheep population with approximately 74.26 million represented by 44 well-described breeds in addition to several non-descript populations. Genetic diversity and phylogeography of Indian sheep breeds remain poorly understood, particularly for south Indian breeds. To have a comprehensive view of the domestication history of Indian sheep, we sequenced the mitochondrial DNA (mtDNA) control region (D-loop) and cytochrome b gene (CYTB) of 16 Indian domestic sheep breeds, most of them (13) from the south India. We analysed these sequences along with published data of domestic and wild sheep from different countries, including India. The haplotype diversity was relatively high in Indian sheep, which were classified into the three known mtDNA lineages, namely A, B and C. Lineage A was predominant among Indian sheep whereas lineages B and C were observed at low frequencies but C was restricted to the breeds of north and east India. The median joining network showed five major expanding haplogroups of lineage A (A1–A5). Out of which, A2, A4 and A5 were more frequent in Indian sheep in contrast to breeds from other parts of the world. Among the 27 Indian sheep breeds analysed, Mandya and Sonadi breeds were significantly different from other Indian breeds in the MDS analyses. This was explained by a very high contribution of lineage B into these two breeds. The Approximate Bayesian Computation (ABC) provided evidence for the domestication of lineage A sheep in the Indian subcontinent. Contrary to the current knowledge, we also found strong support for the introduction of lineage B into Indian subcontinent through sea route rather than from the Mongolian Plateau. The neighbour-joining tree of domestic and wild sheep revealed the close genetic relationship of Indian domestic sheep with Pakistani wild sheep O. vignei blanfordi. Based on our analyses and archaeological evidences, we suggest the Indian subcontinent as one of the domestication centres of the lineage A sheep, while lineage B sheep might have arrived into India from elsewhere via Arabian sea route. To the best of our knowledge, this is the first comprehensive study on Indian sheep where we have analysed more than 740 animals belonging to 27 sheep breeds raised in various regions of India. Our study provides insight into the understanding of the origin and migratory history of Indian sheep.

AbstractIndia ranks the second in the world in terms of its sheep population with approximately 74.26 million represented by 44 well-described breeds in addition to several non-descript populations. Genetic diversity and phylogeography of Indian sheep breeds remain poorly understood, particularly for south Indian breeds. To have a comprehensive view of the domestication history of Indian sheep, we sequenced the mitochondrial DNA (mtDNA) control region (D-loop) and cytochrome b gene (CYTB) of 16 Indian domestic sheep breeds, most of them (13) from the south India. We analysed these sequences along with published data of domestic and wild sheep from different countries, including India. The haplotype diversity was relatively high in Indian sheep, which were classified into the three known mtDNA lineages, namely A, B and C. Lineage A was predominant among Indian sheep whereas lineages B and C were observed at low frequencies but C was restricted to the breeds of north and east India. The median joining network showed five major expanding haplogroups of lineage A (A1–A5). Out of which, A2, A4 and A5 were more frequent in Indian sheep in contrast to breeds from other parts of the world. Among the 27 Indian sheep breeds analysed, Mandya and Sonadi breeds were significantly different from other Indian breeds in the MDS analyses. This was explained by a very high contribution of lineage B into these two breeds. The Approximate Bayesian Computation (ABC) provided evidence for the domestication of lineage A sheep in the Indian subcontinent. Contrary to the current knowledge, we also found strong support for the introduction of lineage B into Indian subcontinent through sea route rather than from the Mongolian Plateau. The neighbour-joining tree of domestic and wild sheep revealed the close genetic relationship of Indian domestic sheep with Pakistani wild sheep O. vignei blanfordi. Based on our analyses and archaeological evidences, we suggest the Indian subcontinent as one of the domestication centres of the lineage A sheep, while lineage B sheep might have arrived into India from elsewhere via Arabian sea route. To the best of our knowledge, this is the first comprehensive study on Indian sheep where we have analysed more than 740 animals belonging to 27 sheep breeds raised in various regions of India. Our study provides insight into the understanding of the origin and migratory history of Indian sheep.

IntroductionFor Gilles Deleuze, computational processes cannot yield the anomalous, or that which is unprecedented in form and content. He suggests that because computing functions are mechanically standardised, they always share the same ontic character. M. Beatrice Fazi claims that the premises of his critique are flawed. Her monograph Contingent Computation: Abstraction, Experience, and Indeterminacy in Computational Aesthetics presents an integrative reading of thinkers including Henri Bergson, Alfred North Whitehead, Kurt Gödel, Alan Turing, and Georg Cantor. From this eclectic basis, Fazi demonstrates that computers differ from humans in their modes of creation, yet still produce qualitative anomaly. This article applies her research to the cultural phenomenon of live-coded music. Live coding artists improvise music by writing audio computer functions which produce sound in real time. I draw from Fazi’s reading of Deleuze and Bergson to investigate the aesthetic mechanisms of live coding. In doing so, I give empirical traction to her argument for the generative properties of computers.Part I: Reconciling the Discrete and the Continuous In his book Difference and Repetition, Deleuze defines “the new” as that which radically differs from the known and familiar (136). Deleuzean novelty bears unpredictable creative potential; as he puts it, the “new” “calls forth forces in thought which are not the forces of recognition” (136). These forces issue from a space of alterity which he describes as a “terra incognita” and a “completely other model” (136). Fazi writes that Deleuze’s conception of novelty informs his aesthetic philosophy. She notes that Deleuze follows the etymological origins of the word “aesthetic”, which lie in the Ancient Greek term aisthēsis, or perception from senses and feelings (Fazi, “Digital Aesthetics” 5). Deleuze observes that senses, feelings, and cognition are interwoven, and suggests that creative processes beget new links between these faculties. In Fazi’s words, Deleuzean aesthetic research “opposes any existential modality that separates life, thought, and sensation” (5). Here, aesthetics does not denote a theory of art and is not concerned with such traditional topics as beauty, taste, and genre. Aesthetics-as-aisthēsis investigates the conditions which make it possible to sense, cognise, and create anomalous phenomena, or that which has no recognisable forebear.Fazi applies Deleuzean aesthetics towards an ontological account of computation. Towards this end, she challenges Deleuze’s precept that computers cannot produce the aesthetic “new”. As she explains, Deleuze denies this ability to computers on the grounds that computation operates on discrete variables, or data which possess a quantitatively finite array of possible values (6). Deleuze understands discreteness as both a quantitative and ontic condition, and implies that computation cannot surpass this originary state. In his view, only continuous phenomena are capable of aisthēsis as the function which yields ontic novelty (5). Moreover, he maintains that continuous entities cannot be represented, interpreted, symbolised, or codified. The codified discreteness of computation is therefore “problematic” within his aesthetic framework “inasmuch it exemplifies yet another development of the representational”. or a repetition of sameness (6). The Deleuzean act of aisthēsis does not compute, repeat, or iterate what has come before. It yields nothing less than absolute difference.Deleuze’s theory of creation as differentiation is prefigured by Bergson’s research on multiplicity, difference and time. Bergson holds that the state of being multiple is ultimately qualitative rather than quantitative, and that multiplicity is constituted by qualitative incommensurability, or difference in kind as opposed to degree (Deleuze, Bergsonism 42). Qualia are multiple when they cannot not withstand equivocation through a common substrate. Henceforth, entities that comprise discrete data, including all products and functions of digital computation, cannot aspire to true multiplicity or difference. In The Creative Mind, Bergson considers the concept of time from this vantage point. As he indicates, time is normally understood as numerable and measurable, especially by mathematicians and scientists (13). He sets out to show that this conception is an illusion, and that time is instead a process by which continuous qualia differentiate and self-actualise as unique instances of pure time, or what he calls “duration as duration”. As he puts it,the measuring of time never deals with duration as duration; what is counted is only a certain number of extremities of intervals, or moments, in short, virtual halts in time. To state that an incident will occur at the end of a certain time t, is simply to say that one will have counted, from now until then, a number t of simultaneities of a certain kind. In between these simultaneities anything you like may happen. (12-13)The in-between space where “anything you like may happen” inspired Deleuze’s notion of ontic continua, or entities whose quantitative limitlessness connects with their infinite aesthetic potentiality. For Bergson, those who believe that time is finite and measurable “cannot succeed in conceiving the radically new and unforeseeable”, a sentiment which also appears to have influenced Deleuze (The Creative Mind 17).The legacy of Bergson and Deleuze is traceable to the present era, where the alleged irreconcilability of the discrete and the continuous fuels debates in digital media studies. Deleuze is not the only thinker to explore this tension: scholars in the traditions of phenomenology, critical theory, and post-Marxism have positioned the continuousness of thought and feeling against the discreteness of computation (Fazi, “Digital Aesthetics” 7). Fazi contributes to this discourse by establishing that the ontic character of computation is not wholly predicated on quantitatively discrete elements. Drawing from Turing’s theory of computability, she claims that computing processes incorporate indeterminable and uncomputable forces in open-ended processes that “determine indeterminacy” (Fazi, Contingent Computation 1). She also marshals philosopher Stamatia Portanova, whose book Moving Without a Body: Digital Philosophy and Choreographic Thoughtsindicates that discrete and continuous components merge in processes that digitise bodily motion (Portanova 3). In a similar but more expansive maneuver, Fazi declares that the discrete and continuous coalesce in all computational operations. Although Fazi’s work applies to all forms of computing, it casts new light on specific devices, methodologies, and human-computer interfaces. In the next section, I use her reading of Bergsonian elements in Deleuze to explore the contemporary artistic practice of live coding. My reading situates live coding in the context of studies on improvisation and creative indeterminacy.Part II: Live Coding as Contingent Improvisational PracticeThe term “live coding” describes an approach to programming where computer functions immediately render as images and/or sound. Live coding interfaces typically feature two windows: one for writing source code and another which displays code outcomes, for example as graphic visualisations or audio. The practice supports the rapid evaluation, editing, and exhibition of code in progress (“A History of Live Programming”). Although it encompasses many different activities, the phrase “live coding” is most often used in the context of computer music. In live coding performances or “AlgoRaves,” musicians write programs on stage in front of audiences. The programming process might be likened to playing an instrument. Typically, the coding interface is projected on a large screen, allowing audiences to see the musical score as it develops (Magnusson, “Improvising with the Threnoscope” 19). Technologists, scholars, and educators have embraced live coding as both a creative method and an object of study. Because it provides immediate feedback, it is especially useful as a pedagogical aide. Sonic Pi, a user-friendly live coding language, was originally designed to teach programming basics to children. It has since been adopted by professional musicians across the world (Aaron). Despites its conspicuousness in educational and creative settings, scholars have rarely explored live coding in the context of improvisation studies. Programmers Gordan Kreković and Antonio Pošćic claim that this is a notable oversight, as improvisation is its “most distinctive feature”. In their view, live coding is most simply defined as an improvisational method, and its strong emphasis on chance sets it apart from other approaches to computer music (Kreković and Pošćić). My interest with respect to live coding lies in how its improvisational mechanisms blend computational discreteness and continuous “real time”. I do not mean to suggest that live coding is the only implement for improvising music with computers. Any digital instrument can be used to spontaneously play, produce, and record sound. What makes live coding unique is that it merges the act of playing with the process of writing notation: musicians play for audiences in the very moment that they produce a written score. The process fuses the separate functions of performing, playing, seeing, hearing, and writing music in a patently Deleuzean act of aisthēsis. Programmer Thor Magnusson writes that live coding is the “offspring” of two very different creative practices: first, “the formalization and encoding of music”; second, “open work resisting traditional forms of encoding” (“Algorithms as Scores” 21). By “traditional forms of encoding”, Magnusson refers to computer programs which function only insofar as source code files are static and immutable. By contrast, live coding relies on the real-time elaboration of new code. As an improvisational art, the process and product of live-coding does not exist without continuous interventions from external forces.My use of the phrase “real time” evokes Bergson’s concept of “pure time” or “duration as duration”. “Real time” phenomena are understood to occur instantaneously, that is, at no degree of temporal removal from those who produce and experience them. However, Bergson suggests that instantaneity is a myth. By his account, there always exists some degree of removal between events as they occur and as they are perceived, even if this gap is imperceptibly small. Regardless of size, the indelible space in time has important implications for theories of improvisation. For Deleuze and Bergson, each continuous particle of time is a germinal seed for the new. Fazi uses the word “contingent” to describe this ever-present, infinite potentiality (Contingent Computation, 1). Improvisation studies scholar Dan DiPiero claims that the concept of contingency not only qualifies future possibilities, but also describes past events that “could have been otherwise” (2). He explains his reasoning as follows:before the event, the outcome is contingent as in not-yet-known; after the event, the result is contingent as in could-have-been-otherwise. What appears at first blush a frustrating theoretical ambiguity actually points to a useful insight: at any given time in any given process, there is a particular constellation of openings and closures, of possibilities and impossibilities, that constitute a contingent situation. Thus, the contingent does not reference either the open or the already decided but both at once, and always. (2)Deleuze might argue that only continuous phenomena are contingent, and that because they are quantitatively finite, the structures of computational media — including the sound and notation of live coding scores — can never “be otherwise” or contingent as such. Fazi intervenes by indicating the role of quantitative continuousness in all computing functions. Moreover, she aligns her project with emerging theories of computing which “focus less on internal mechanisms and more on external interaction”, or interfaces with continuous, non-computational contexts (“Digital Aesthetics,” 19). She takes computational interactions with external environments, such as human programmers and observers, as “the continuous directionality of composite parts” (19).To this point, it matters that discrete objects always exist in relation to continuous environments, and that discrete objects make up continuous fluxes when mobilised as part of continuous temporal processes. It is for this reason that Portanova uses the medium of dance to explore the entanglement of discreteness and temporal contingency. As with music, the art of dance depends on the continuous unfolding of time. Fazi writes that Portanova’s study of choreography reveals “the unlimited potential that every numerical bit of a program, or every experiential bit of a dance (every gesture and step), has to change and be something else” (Contingent Computation, 39). As with the zeroes and ones of a binary computing system, the footfalls of a dance materialise as discrete parts which inhabit and constitute continuous vectors of time. Per Deleuzean aesthetics-as-aisthēsis, these parts yield new connections between sound, space, cognition, and feeling. DiPiero indicates that in the case of improvised artworks, the ontic nature of these links defies anticipation. In his words, improvisation forces artists and audiences to “think contingency”. “It is not that discrete, isolated entities connect themselves to form something greater”, he explains, “but rather that the distance between the musician as subject and the instrument as object is not clearly defined” (3). So, while live coder and code persist as separate phenomena, the coding/playing/performing process highlights the qualitative indeterminacy of the space between them. Each moment might beget the unrecognisable — and this ineluctable, ever-present surprise is essential to the practice.To be sure, there are elements of predetermination in live coding practices. For example, musicians often save and return to specific functions in the midst of performances. But as Kreković and Pošćić point out all modes of improvisation rely on patterning and standardisation, including analog and non-computational techniques. Here, they cite composer John Cage’s claim that there exists no “true” improvisation because artists “always find themselves in routines” (Kreković and Pošćić). In a slight twist on Cage, Kreković and Pošćić insist that repetition does not make improvisation “untrue”, but rather that it points to an expanded role for indeterminacy in all forms of composition. As they write,[improvisation] can both be viewed as spontaneous composition and, when distilled to its core processes, a part of each compositional approach. Continuous and repeated improvisation can become ingrained, classified, and formalised. Or, if we reverse the flow of information, we can consider composition to be built on top of quiet, non-performative improvisations in the mind of the composer. (Kreković and Pošćić)This commentary echoes Deleuze’s thoughts on creativity and ontic continuity. To paraphrase Kreković and Pošćić, the aisthēsis of sensing, feeling, and thinking yields quiet, non-performative improvisations that play continuously in each individual mind. Fazi’s reading of Deleuze endows computable phenomena with this capacity. She does not endorse a computational theory of cognition that would permit computers to think and feel in the same manner as humans. Instead, she proposes a Deleuzean aesthetic capacity proper to computation. Live coding exemplifies the creative potential of computers as articulated by Fazi in Contingent Computation. Her research has allowed me to indicate live coding as an embodiment of Deleuze and Bergson’s theories of difference and creativity. Importantly, live coding affirms their philosophical premises not in spite of its technologised discreteness — which they would have considered problematic — but because it leverages discreteness in service of the continuous aesthetic act. My essay might also serve as a prototype for studies on digitality which likewise aim to supersede the divide between discrete and continuous media. As I have hopefully demonstrated, Fazi’s framework allows scholars to apprehend all forms of computation with enhanced clarity and openness to new possibilities.Coda: From Aesthetics to PoliticsBy way of a coda, I will reflect on the relevance of Fazi’s work to contemporary political theory. In “Digital Aesthetics”, she makes reference to emerging “oppositions to the mechanization of life” from “post-structuralist, postmodernist and post-Marxist” perspectives (7). One such argument comes from philosopher Bernard Stiegler, whose theory of psychopower conceives “the capture of attention by technological means” as a political mechanism (“Biopower, Psychopower and the Logic of the Scapegoat”). Stiegler is chiefly concerned with the psychic impact of discrete technological devices. As he argues, the habitual use of these instruments advances “a proletarianization of the life of the mind” (For a New Critique of Political Economy 27). For Stiegler, human thought is vulnerable to discretisation processes, which effects the loss of knowledge and quality of life. He considers this process to be a form of political hegemony (34).Philosopher Antoinette Rouvroy proposes a related theory called “algorithmic governmentality” to describe the political effects of algorithmic prediction mechanisms. As she claims, predictive algorithms erode “the excess of the possible on the probable”, or all that cannot be accounted for in advance by statistical probabilities. In her words,all these events that can occur and that we cannot predict, it is the excess of the possible on the probable, that is everything that escapes it, for instance the actuarial reality with which we try precisely to make the world more manageable in reducing it to what is predictable … we have left this idea of the actuarial reality behind for what I would call a “post-actuarial reality” in which it is no longer about calculating probabilities but to account in advance for what escapes probability and thus the excess of the possible on the probable. (8)In the past five years, Stiegler and Rouvroy have collaborated on research into the politics of technological determinacy. The same issue concerned Deleuze almost three decades ago: his 1992 essay “Postscript on the Societies of Control” warns that future subjugation will proceed as technological prediction and enclosure. He writes of a dystopian society which features a “numerical language of control … made of codes that mark access to information, or reject it” (5). The society of control reduces individuals to “dividuals”, or homogenised and interchangeable numeric fractions (5). These accounts of political power equate digital discreteness with ontic finitude, and suggest that ubiquitous digital computing threatens individual agency and societal diversity. Stiegler and Deleuze envision a sort of digital reification of human subjectivity; Rouvroy puts forth the idea that algorithmic development will reduce the possibilities inherent in social life to mere statistical likelihoods. While Fazi’s work does not completely discredit these notions, it might instead be used to scrutinise their assumptions. If computation is not ontically finite, then political allegations against it must consider its opposition to human life with greater nuance and rigor.ReferencesAaron, Sam. “Programming as Performance.” Tedx Talks. YouTube, 22 July 2015. <https://www.youtube.com/watch?v=TK1mBqKvIyU&t=333s>.“A History of Live Programming.” Live Prog Blog. 13 Jan. 2013. <liveprogramming.github.io/liveblog/2013/01/a-history-of-live-programming/>.Bergson, Henri. The Creative Mind: An Introduction to Metaphysics. Trans. Mabelle L. Andison. New York City: Carol Publishing Group, 1992.———. Time and Free Will: An Essay on the Immediate Data of Consciousness. Trans. F.L. Pogson. Mineola: Dover Publications, 2001.Deleuze, Gilles. Difference and Repetition. Trans. Paul Patton. New York City: Columbia UP, 1994.———. "Postscript on the Societies of Control." October 59 (1992): 3-7.———. Bergsonism. Trans. Hugh Tomlinson and Barbara Habberjam. New York City: Zone Books, 1991.DiPiero, Dan. “Improvisation as Contingent Encounter, Or: The Song of My Toothbrush.” Critical Studies in Improvisation / Études Critiques en Improvisation 12.2 (2018). <https://www.criticalimprov.com/index.php/csieci/article/view/4261>.Fazi, M. Beatrice. Contingent Computation: Abstraction, Experience, and Indeterminacy in Computational Aesthetics. London: Rowman & Littlefield International, 2018.———. “Digital Aesthetics: The Discrete and the Continuous.” Theory, Culture & Society 36.1 (2018): 3-26.Fortune, Stephen. “What on Earth Is Livecoding?” Dazed Digital, 14 May 2013. <https://www.dazeddigital.com/artsandculture/article/16150/1/what-on-earth-is-livecoding>.Kreković, Gordan, and Antonio Pošćić. “Modalities of Improvisation in Live Coding.” Proceedings of xCoaX 2019, the 7th Conference on Computation, Communication, Aesthetics & X. Fabbrica del Vapore, Milan, Italy, 5 July 2019.Magnusson, Thor. “Algorithms as Scores: Coding Live Music.” Leonardo Music Journal 21 (2011): 19-23. ———. “Improvising with the Threnoscope: Integrating Code, Hardware, GUI, Network, and Graphic Scores.” Proceedings of the International Conference on New Interfaces for Musical Expression. Goldsmiths, University of London, London, England, 1 July 2014.Portanova, Stamatia. Moving without a Body: Digital Philosophy and Choreographic Thoughts. Cambridge, MA: The MIT P, 2013.Rouvroy, Antoinette.“The Digital Regime of Truth: From the Algorithmic Governmentality to a New Rule of Law.” Trans. Anaïs Nony and Benoît Dillet. La Deleuziana: Online Journal of Philosophy 3 (2016). <http://www.ladeleuziana.org/wp-content/uploads/2016/12/Rouvroy-Stiegler_eng.pdf>Stiegler, Bernard. For a New Critique of Political Economy. Malden: Polity Press, 2012.———. “Biopower, Psychopower and the Logic of the Scapegoat.” Ars Industrialis (no date given). <www.arsindustrialis.org/node/2924>.

Predictive computation of the nonlinear dynamical responses of gap-supported tubes subjected to flow excitation has been the subject of very active research. Nevertheless, experimental results are still very important, for validation of the theoretical predictions as well as for asserting the integrity of field components. Because carefully instrumented test tubes and tube-supports are seldom possible, due to space limitations and to the severe environment conditions, there is a need for robust techniques capable of extracting, from the actual vibratory response data, information that is relevant for asserting the components integrity. The dynamical contact/impact (vibro-impact) forces are of paramount significance, as are the tube/support gaps. Following our previous studies in this area using wave-propagation techniques (De Araújo, Antunes, and Piteau, 1998, “Remote Identification of Impact Forces on Loosely Supported Tubes: Part 1—Basic Theory and Experiments,” J. Sound Vib., 215, pp. 1015–1041; Antunes, Paulino, and Piteau, 1998, “Remote Identification of Impact Forces on Loosely Supported Tubes: Part 2—Complex Vibro-Impact Motions,” J. Sound Vib., 215, pp. 1043–1064; Paulino, Antunes, and Izquierdo, 1999, “Remote Identification of Impact Forces on Loosely Supported Tubes: Analysis of Multi-Supported Systems,” ASME J. Pressure Vessel Technol., 121, pp. 61–70), we apply modal methods in the present paper for extracting such information. The dynamical support forces, as well as the vibratory responses at the support locations, are identified from one or several vibratory response measurements at remote transducers, from which the support gaps can be inferred. As for most inverse problems, the identification results may prove quite sensitive to noise and modeling errors. Therefore, topics discussed in the paper include regularization techniques to mitigate the effects of nonmeasured noise perturbations. In particular, a method is proposed to improve the identification of contact forces at the supports when the system is excited by an unknown distributed turbulence force field. The extensive identification results presented are based on realistic numerical simulations of gap-supported tubes subjected to flow turbulence excitation. We can thus confront the identified dynamical support contact forces and vibratory motions at the gap-support with the actual values stemming from the original nonlinear computations. The important topic of dealing with the imperfect knowledge of the modal parameters used to build the inverted transfer functions is thoroughly addressed elsewhere (Debut, Delaune, and Antunes, 2009, “Identification of Nonlinear Interaction Forces Acting on Continuous Systems Using Remote Measurements of the Vibratory Responses,” Proceedings of the Seventh EUROMECH Solids Mechanics Conference (ESMC2009), Lisbon, Portugal, Sept. 7–11). Nevertheless, identifications are performed in this paper based on both the exact modes and also on randomly perturbed modal parameters. Our results show that, for the system addressed here, deterioration of the identifications is moderate when realistic errors are introduced in the modal parameters. In all cases, the identified results compare reasonably well with the real contact forces and motions at the gap-supports.

This paper argues that artist Dope Saint Jude is transforming South African hip-hop by queering a genre that has predominantly been male and heteronormative. Specifically, I analyse the opening skit of her music video “Keep in Touch” in order to unpack the ways which she revives Gayle, a gay language that adopted double-coded forms of speech during the apartheid era—a context in which homosexuals were criminalised. The use of Gayle and spaces close to the city centre of Cape Town (such as Salt River and Woodstock) speaks to the city as it was before it was transformed by the decline of industries due to the country’s adoption of neoliberal economics and, more recently, by the gentrification of these spaces. Dope Saint Jude therefore reclaims these city spaces through her use of gay modes of speech that have a long history in Cape Town and by positioning her work as hip-hop, which has been popular in the city for well over two decades. Her inclusion of transgender MC and DJ Angel Ho pushes the boundaries of hegemonic and binary conceptions of gender identity even further. In essence, Dope Saint Jude is transforming local hip-hop in a context that is shaped significantly by US cultural imperialism. The artist is also transforming our perspective of spaces that have been altered by neoliberal economics.Setting the SceneDope Saint Jude (DSJ) is a queer MC from Elsies River, a working class township located on Cape Town's Cape Flats in South Africa. Elsies River was defined as a “coloured” neighbourhood under the apartheid state's Group Areas Act, which segregated South Africans racially. With the aid of the Population Registration Act, citizens were classified, not merely along the lines of white, Asian, or black—black subjects were also divided into further categories. The apartheid state also distinguished between black and “coloured” subjects. Michael MacDonald contends that segregation “ordained blacks to be inferior to whites; apartheid cast them to be indelibly different” (11). Apartheid declared “African claims in South Africa to be inferior to white claims” and effectively claimed that black subjects “belonged elsewhere, in societies of their own, because their race was different” (ibid). The term “coloured” defined people as “mixed race” to separate communities that might otherwise have identified as black in the broad and inclusive sense (Erasmus 16). Racial categorisation was used to create a racial hierarchy with white subjects at the top of that hierarchy and those classified as black receiving the least resources and benefits. This frustrated attempts to establish broad alliances of black struggles against apartheid. It is in this sense that race is socially and politically constructed and continues to have currency, despite the fact that biologically essentialist understandings of race have been discredited (Yudell 13–14). Thanks to apartheid town planning and resource allocation, many townships on the Cape Flats were poverty-stricken and plagued by gang violence (Salo 363). This continues to be the case because post-apartheid South Africa's embrace of neoliberal economics failed to address racialised class inequalities significantly (Haupt, Static 6–8). This is the '90s context in which socially conscious hip-hop crews, such as Prophets of da City or Black Noise, came together. They drew inspiration from Black Consciousness philosophy via their exposure to US hip-hop crews such as Public Enemy in order to challenge apartheid policies, including their racial interpellation as “coloured” as distinct from the more inclusive category, black (Haupt, “Black Thing” 178). Prophets of da City—whose co-founding member, Shaheen Ariefdien, also lived in Elsies River—was the first South African hip-hop outfit to record an album. Whilst much of their work was performed in English, they quickly transformed the genre by rapping in non-standard varieties of Afrikaans and by including MCs who rap in African languages (ibid). They therefore succeeded in addressing key issues related to race, language, and class disparities in relation to South Africa's transition to democracy (Haupt, “Black Thing”; Haupt, Stealing Empire). However, as is the case with mainstream US hip-hop, specifically gangsta rap (Clay 149), South African hip-hop has been largely dominated by heterosexual men. This includes the more commercial hip-hop scene, which is largely perceived to be located in Johannesburg, where male MCs like AKA and Cassper Nyovest became celebrities. However, certain female MCs have claimed the genre, notably EJ von Lyrik and Burni Aman who are formerly of Godessa, the first female hip-hop crew to record and perform locally and internationally (Haupt, Stealing Empire 166; Haupt, “Can a Woman in Hip-Hop”). DSJ therefore presents the exception to a largely heteronormative and male-dominated South African music industry and hip-hop scene as she transforms it with her queer politics. While queer hip-hop is not new in the US (Pabón and Smalls), this is new territory for South Africa. Writing about the US MC Jean Grae in the context of a “male-dominated music industry and genre,” Shanté Paradigm Smalls contends,Heteronormativity blocks the materiality of the experiences of Black people. Yet, many Black people strive for a heteronormative effect if not “reality”. In hip hop, there is a particular emphasis on maintaining the rigidity of categories, even if those categories fail [sic]. (87) DSJ challenges these rigid categories. Keep in TouchDSJ's most visible entry onto the media landscape to date has been her appearance in an H&M recycling campaign with British Sri Lankan artist MIA (H&M), some fashion shoots, her new EP—Reimagine (Dope Saint Jude)—and recent Finnish, US and French tours as well as her YouTube channel, which features her music videos. As the characters’ theatrical costumes suggest, “Keep in Touch” is possibly the most camp and playful music video she has produced. It commences somewhat comically with Dope Saint Jude walking down Salt River main road to a public telephone, where she and a young woman in pig tails exchange dirty looks. Salt River is located at the foot of Devil's Peak not far from Cape Town's CBD. Many factories were located there, but the area is also surrounded by low-income housing, which was designated a “coloured” area under apartheid. After apartheid, neighbourhoods such as Salt River, Woodstock, and the Bo-Kaap became increasingly gentrified and, instead of becoming more inclusive, many parts of Cape Town continued to be influenced by policies that enable racialised inequalities. Dope Saint Jude calls Angel Ho: DSJ: Awêh, Angie! Yoh, you must check this kak sturvy girl here by the pay phone. [Turns to the girl, who walks away as she bursts a chewing gum bubble.] Ja, you better keep in touch. Anyway, listen here, what are you wys?Angel Ho: Ah, just at the salon getting my hair did. What's good? DSJ: Wanna catch on kak today?Angel Ho: Yes, honey. But, first, let me Gayle you this. By the jol by the art gallery, this Wendy, nuh. This Wendy tapped me on the shoulder and wys me, “This is a place of decorum.”DSJ: What did she wys?Angel Ho: De-corum. She basically told me this is not your house. DSJ: I know you told that girl to keep in touch!Angel Ho: Yes, Mama! I'm Paula, I told that bitch, “Keep in touch!” [Points index finger in the air.](Saint Jude, Dope, “Keep in Touch”)Angel Ho's name is a play on the male name Angelo and refers to the trope of the ho (whore) in gangsta rap lyrics and in music videos that present objectified women as secondary to male, heterosexual narratives (Sharpley-Whiting 23; Collins 27). The queering of Angelo, along with Angel Ho’s non-binary styling in terms of hair, make-up, and attire, appropriates a heterosexist, sexualised stereotype of women in order to create room for a gender identity that operates beyond heteronormative male-female binaries. Angel Ho’s location in a hair salon also speaks to stereotypical associations of salons with women and gay subjects. In a discussion of gender stereotypes about hair salons, Kristen Barber argues that beauty work has traditionally been “associated with women and with gay men” and that “the body beautiful has been tightly linked to the concept of femininity” (455–56). During the telephonic exchange, Angel Ho and Dope Saint Jude code-switch between standard and non-standard varieties of English and Afrikaans, as the opening appellation, “Awêh,” suggests. In this context, the term is a friendly greeting, which intimates solidarity. “Sturvy” means pretentious, whilst “kak” means shit, but here it is used to qualify “sturvy” and means that the girl at the pay phone is very pretentious or “full of airs.” To be “wys” means to be wise, but it can also mean that you are showing someone something or educating them. The meanings of these terms shift, depending on the context. The language practices in this skit are in line with the work of earlier hip-hop crews, such as Prophets of da City and Brasse vannie Kaap, to validate black, multilingual forms of speech and expression that challenge the linguistic imperialism of standard English and Afrikaans in South Africa, which has eleven official languages (Haupt, “Black Thing”; Haupt, Stealing Empire; Williams). Henry Louis Gates’s research on African American speech varieties and literary practices emerging from the repressive context of slavery is essential to understanding hip-hop’s language politics. Hip-hop artists' multilingual wordplay creates parallel discursive universes that operate both on the syntagmatic axis of meaning-making and the paradigmatic axis (Gates 49; Haupt, “Stealing Empire” 76–77). Historically, these discursive universes were those of the slave masters and the slaves, respectively. While white hegemonic meanings are produced on the syntagmatic axis (which is ordered and linear), black modes of speech as seen in hip-hop word play operate on the paradigmatic axis, which is connotative and non-linear (ibid). Distinguishing between Signifyin(g) / Signification (upper case, meaning black expression) and signification (lower case, meaning white dominant expression), he argues that “the signifier ‘Signification’ has remained identical in spelling to its white counterpart to demonstrate [. . .] that a simultaneous, but negated, parallel discursive (ontological, political) universe exists within the larger white discursive universe” (Gates 49). The meanings of terms and expressions can change, depending on the context and manner in which they are used. It is therefore the shared experiences of speech communities (such as slavery or racist/sexist oppression) that determine the negotiated meanings of certain forms of expression. Gayle as a Parallel Discursive UniverseDSJ and Angel Ho's performance of Gayle takes these linguistic practices further. Viewers are offered points of entry into Gayle via the music video’s subtitles. We learn that Wendy is code for a white person and that to keep in touch means exactly the opposite. Saint Jude explains that Gayle is a very fun queer language that was used to kind of mask what people were saying [. . .] It hides meanings and it makes use of women's names [. . . .] But the thing about Gayle is it's constantly changing [. . .] So everywhere you go, you kind of have to pick it up according to the context that you're in. (Ovens, Saint Jude and Haupt)According to Kathryn Luyt, “Gayle originated as Moffietaal [gay language] in the coloured gay drag culture of the Western Cape as a form of slang amongst Afrikaans-speakers which over time, grew into a stylect used by gay English and Afrikaans-speakers across South Africa” (Luyt 8; Cage 4). Given that the apartheid state criminalised homosexuals, Gayle was coded to evade detection and to seek out other members of this speech community (Luyt 8). Luyt qualifies the term “language” by arguing, “The term ‘language’ here, is used not as a constructed language with its own grammar, syntax, morphology and phonology, but in the same way as linguists would discuss women’s language, as a way of speaking, a kind of sociolect” (Luyt 8; Cage 1). However, the double-coded nature of Gayle allows one to think of it as creating a parallel discursive universe as Gates describes it (49). Whereas African American and Cape Flats discursive practices function parallel to white, hegemonic discourses, gay modes of speech run parallel to heteronormative communication. Exclusion and MicroaggressionsThe skit brings both discursive practices into play by creating room for one to consider that DSJ queers a male-dominated genre that is shaped by US cultural imperialism (Haupt, Stealing Empire 166) as a way of speaking back to intersectional forms of marginalisation (Crenshaw 1244), which are created by “white supremacist capitalist patriarchy” (hooks 116). This is significant in South Africa where “curative rape” of lesbians and other forms of homophobic violence are prominent (cf. Gqola; Hames; Msibi). Angel Ho's anecdote conveys a sense of the extent to which black individuals are subject to scrutiny. Ho's interpretation of the claim that the gallery “is a place of decorum” is correct: it is not Ho's house. Black queer subjects are not meant to feel at home or feel a sense of ownership. This functions as a racial microaggression: “subtle insults (verbal, nonverbal, and/or visual) directed toward people of color, often automatically or unconsciously” (Solorzano, Ceja, and Yosso 60). This speaks to DSJ's use of Salt River, Woodstock, and Bo-Kaap for the music video, which features black queer bodies in performance—all of these spaces are being gentrified, effectively pushing working class people of colour out of the city (cf. Didier, Morange, and Peyroux; Lemanski). Gustav Visser explains that gentrification has come to mean a unit-by-unit acquisition of housing which replaces low-income residents with high-income residents, and which occurs independent of the structural condition, architecture, tenure or original cost level of the housing (although it is usually renovated for or by the new occupiers). (81–82) In South Africa this inequity plays out along racial lines because its neoliberal economic policies created a small black elite without improving the lives of the black working class. Instead, the “new African bourgeoisie, because it shares racial identities with the bulk of the poor and class interests with white economic elites, is in position to mediate the reinforcing cleavages between rich whites and poor blacks without having to make more radical changes” (MacDonald 158). In a news article about a working class Salt River family of colour’s battle against an eviction, Christine Hogg explains, “Gentrification often means the poor are displaced as the rich move in or buildings are upgraded by new businesses. In Woodstock and Salt River both are happening at a pace.” Angel Ho’s anecdote, as told from a Woodstock hair salon, conveys a sense of what Woodstock’s transformation from a coloured, working class Group Area to an upmarket, trendy, and arty space would mean for people of colour, including black, queer subjects. One could argue that this reading of the video is undermined by DSJ’s work with global brand H&M. Was she was snared by neoliberal economics? Perhaps, but one response is that the seeds of any subculture’s commercial co-option lie in the fact it speaks through commodities (for example clothing, make-up, CDs, vinyl, or iTunes / mp3 downloads (Hebdige 95; Haupt, Stealing Empire 144–45). Subcultures have a window period in which to challenge hegemonic ideologies before they are delegitimated or commercially co-opted. Hardt and Negri contend that the means that extend the reach of corporate globalisation could be used to challenge it from within it (44–46; Haupt, Stealing Empire 26). DSJ utilises her H&M work, social media, the hip-hop genre, and international networks to exploit that window period to help mainstream black queer identity politics.ConclusionDSJ speaks back to processes of exclusion from the city, which was transformed by apartheid and, more recently, gentrification, by claiming it as a creative and playful space for queer subjects of colour. She uses Gayle to lay claim to the city as it has a long history in Cape Town. In fact, she says that she is not reviving Gayle, but is simply “putting it on a bigger platform” (Ovens, Saint Jude, and Haupt). The use of subtitles in the video suggests that she wants to mainstream queer identity politics. Saint Jude also transforms hip-hop heteronormativity by queering the genre and by locating her work within the history of Cape hip-hop’s multilingual wordplay. ReferencesBarber, Kristin. “The Well-Coiffed Man: Class, Race, and Heterosexual Masculinity in the Hair Salon.” Gender and Society 22.4 (2008): 455–76.Cage, Ken. “An Investigation into the Form and Function of Language Used by Gay Men in South Africa.” Rand Afrikaans University: MA thesis, 1999.Clay, Andreana. “‘I Used to Be Scared of the Dick’: Queer Women of Color and Hip-Hop Masculinity.” Home Girls Make Some Noise: Hip Hop Feminism Anthology. Ed. Gwendolyn D. Pough, Elain Richardson, Aisha Durham, and Rachel Raimist. California: Sojourns, 2007.Collins, Patricia Hill. Black Sexual Politics: African Americans, Gender, and the New Racism. New York: Routledge, 2005. Crenshaw, Kimberle. “Mapping the Margins: Intersectionality, Identity Politics, and Violence against Women of Color”. Stanford Law Review 43.6 (1991): 1241–299.Didier, Sophie, Marianne Morange, and Elisabeth Peyroux. “The Adaptative Nature of Neoliberalism at the Local Scale: Fifteen Years of City Improvement Districts in Cape Town and Johannesburg.” Antipode 45.1 (2012): 121–39.Erasmus, Zimitri. “Introduction.” Coloured by History, Shaped by Place. Ed. Zimitri Erasmus. Cape Town: Kwela Books & SA History Online, 2001. Gates, Henry Louis. The Signifying Monkey: A Theory of Afro-American Literary Criticism. Oxford: Oxford UP, 1988.Gqola, Pumla Dineo. Rape: A South African Nightmare. Johannesburg: Jacana, 2015.Hames, Mary. “Violence against Black Lesbians: Minding Our Language.” Agenda 25.4 (2011): 87–91.Hardt, Michael, and Antonio Negri. Empire. London: Harvard UP, 2000.Haupt, Adam. “Can a Woman in Hip Hop Speak on Her Own Terms?” Africa Is a Country. 23 Mar. 2015. <http://africasacountry.com/2015/03/the-double-consciousness-of-burni-aman-can-a-woman-in-hip-hop-speak-on-her-own-terms/>.Haupt, Adam. Static: Race & Representation in Post-Apartheid Music, Media & Film. Cape Town: HSRC Press, 2012. Haupt, Adam. Stealing Empire: P2P, Intellectual Property and Hip-Hop Subversion. Cape Town: HSRC Press, 2008. Haupt, Adam. “Black Thing: Hip-Hop Nationalism, ‘Race’ and Gender in Prophets of da City and Brasse vannie Kaap.” Coloured by History, Shaped by Place. Ed. Zimitri Erasmus. Cape Town: Kwela Books & SA History Online, 2001. Hebdige, Dick. Subculture: The Meaning of Style. London: Routledge, 1979.Hogg, Christine. “In Salt River Gentrification Often Means Eviction: Family Set to Lose Their Home of 11 Years.” Ground Up. 15 June 2016. <http://www.groundup.org.za/article/salt-river-gentrification-often-means-eviction/>.hooks, bell. Outlaw: Culture: Resisting Representations. New York: Routledge, 1994.Lemanski, Charlotte. “Hybrid Gentrification in South Africa: Theorising across Southern and Northern Cities.” Urban Studies 51.14 (2014): 2943–60.Luyt, Kathryn. “Gay Language in Cape Town: A Study of Gayle – Attitudes, History and Usage.” University of Cape Town: MA thesis, 2014.MacDonald, Michael. Why Race Matters in South Africa. University of Kwazulu-Natal Press: Scottsville, 2006.Msibi, Thabo. “Not Crossing the Line: Masculinities and Homophobic Violence in South Africa”. Agenda. 23.80 (2009): 50–54.Pabón, Jessica N., and Shanté Paradigm Smalls. “Critical Intimacies: Hip Hop as Queer Feminist Pedagogy.” Women & Performance: A Journal of Feminist Theory (2014): 1–7.Salo, Elaine. “Negotiating Gender and Personhood in the New South Africa: Adolescent Women and Gangsters in Manenberg Township on the Cape Flats.” Journal of European Cultural Studies 6.3 (2003): 345–65.Solórzano, Daniel, Miguel Ceja, and Tara Yosso. “Critical Race Theory, Racial Microaggressions, and Campus Racial Climate: The Experiences of African American College Students.” Journal of Negro Education 69.1/2 (2000): 60–73.Sharpley-Whiting, T. Denean. Pimps Up, Ho’s Down: Hip Hop’s Hold on Young Black Women. New York: New York UP, 2007.Smalls, Shanté Paradigm. “‘The Rain Comes Down’: Jean Grae and Hip Hop Heteronormativity.” American Behavioral Scientist 55.1 (2011): 86–95.Visser, Gustav. “Gentrification: Prospects for Urban South African Society?” Acta Academica Supplementum 1 (2003): 79–104.Williams, Quentin E. “Youth Multilingualism in South Africa’s Hip-Hop Culture: a Metapragmatic Analysis.” Sociolinguistic Studies 10.1 (2016): 109–33.Yudell, Michael. “A Short History of the Race Concept.” Race and the Genetic Revolution: Science, Myth, and Culture. Ed. Sheldon Krimsky and Kathleen Sloan. New York: Columbia UP, 2011.InterviewsOvens, Neil, Dope Saint Jude, and Adam Haupt. One FM Radio interview. Cape Town. 21 Apr. 2016.VideosSaint Jude, Dope. “Keep in Touch.” YouTube. 23 Feb. 2015. <https://www.youtube.com/watch?v=w2ux9R839lE>. H&M. “H&M World Recycle Week Featuring M.I.A.” YouTube. 11 Apr. 2016. <https://www.youtube.com/watch?v=f7MskKkn2Jg>. MusicSaint Jude, Dope. Reimagine. 15 June 2016. <https://dopesaintjude.bandcamp.com/album/reimagine>.

This article aims to analyse an intercultural telephone invitation given by a Chinese tutor to an Australian student, and highlight general principles of intercultural invitations. This anecdote is based on a true story that took place in a university in Australia, but the persons' names used here are fictitious for the sake of confidentiality. Below is the transcript of the actual conversation between the Chinese tutor Dr Lin Liang (L) and his student Catherine Jones (C): C: Catherine speaking. L: Hi, Catherine, this is Lin. C: Hi, Teacher Lin. L: I would like to invite you to our New Year's party to be held in my house this Saturday evening. C: This Saturday? I am afraid I won't be able to make it because I am going to my best friend's birthday party. L: You know this is the end of our school year. It would be so nice for all of our classmates to gather together. C: But I have already promised my friend. L: En... It is a pity... C: Sorry about that, but -- L: Never mind. Enjoy your party then. C: Thanks. L: That's OK, bye. C: Bye. However, the story does not end here. About two hours later, Dr Lin rang Catherine a second time, asking if it was still possible for her to consider attending the Saturday party. Late in the evening around 9.00 pm, Dr Lin rang her yet again to invite her to the party, saying it would be OK even if she stayed just for a short while. The next day, Catherine lodged a complaint with the Dean, alleging that Dr. Lin's repeated calls constituted sexual harassment. Dr. Lin was highly distressed to learn of the complaint, and explained that he just wanted to indicate sincerity and warmth as required by an invitation, and had no other intentions. This communication breakdown invites a number of questions: What are the factors underlying Catherine's interpretation that Dr. Lin's repeated calls constituted sexual harassment? What are the factors underlying Dr. Lin's contention that his actions were intended to emphasise his sincerity? What factors would need to be recognised in order to facilitate culturally competent performances on both their parts? In order to answer these questions, this article will adopt a holistic approach based on an analytic framework encompassing three theoretical dimensions. This framework is comprised as follows: Differences in intercultural exchange and politeness behaviour; Aristotle's distinction between the three orientations of persuasive/rhetorical appeal; ethos, pathos, and logos; Austin and Searle's theory of speech acts, as applied to politeness behaviour and felicity conditions in communicative interaction as applied to the act of inviting. These approaches are conceptualised as three overlapping spheres, and their relatedness can be further illustrated: Figure 1 First and foremost, the case study in question is related to an intercultural interaction between the Australian and Chinese culture, and some research findings in relevant areas may help highlight the differences in politeness behaviour between high-context and low-context cultures (Hall). According to Hall, high-context cultures such as Chinese tend to stress the use of internalised or implicit message while low-context cultures tend to emphasise the use of explicit messages. In other words, in Chinese culture, the message may have some shared implied meanings that may go beyond the linguistic forms used in the message. Kaplan's model on oriental circularity and western linearity seemed to in accordance with Hall's model. Young's exploration of the directness and indirectness of American and Chinese requests further substantiated this point. In a similar way, differences may arise in determining the criteria for appropriate behaviour relating to the use of other directives across cultures. As Gao and Ting-Toomey suggest, Chinese culture seems to pay attention to qing (reciprocity and feelings of obligation) and guanxi (relationship building), while in low-context cultures such a stress tends to be missing. This difference may also help explain the differences in communicative patterns as discussed by Kaplan and Young. Zhu found that in making a sales offer, Chinese companies often try to establish a long-term relationship with their clients ("Structural Moves"). In contrast, Australian companies seem to mainly focus on promoting products. The stress on qing in Chinese culture may also be a crucial factor that contributes to the different criteria for a polite invitation as compared to the Australian culture. The following discussion will further explore the other two parameters (see Figure 1) the two cultures differ in when making an invitation, which may have finally led to the breakdown in communication between Dr. Lin and Catherine. As shown in Figure 1, the argument underpinning this approach is that a given illocutionary act reflects culture-specific preferences for certain persuasive/rhetorical orientations, thereby affecting the socio-linguistic performance, i.e. parole as opposed to langue (Cullen) related to politeness principles. In short, the persuasive/rhetorical orientation varies between cultures, which means that the nature of ostensibly equivalent illocutionary acts also varies. Consequently, cross-cultural competence will be limited unless one is aware of the rhetorical and politeness codes implicit in the performance of certain communicative actions. Note that rhetorical orientation may also influence the politeness behaviour directly as a specification of that orientation. This in turn requires an awareness of cultural preferences toward certain persuasive/rhetorical orientations. The interconnections between them and the theoretical utility of this approach will be made explicit in the course of this discussion. Austin and Searle conceptualise the speech acts as comprising of locution (langue) and illocution (parole). What is of vital importance is the illocutionary force of an utterance which is the performance of a speech act, such as an invitation. According to Searle, an invitation is a directive used to get the addressee to do something. Invitation can be understood as a particular form of persuasive speech act. It is generally intended to produce a particular response (i.e. acceptance). As an illocutionary action, an invitation seeks to establish a relationship of social expectations between the host and invitee. This requires certain felicity conditions to be met. In other words, for the speech act to be socially significant, it must create a shared sense of meaning in regard to some perceived change or modification to existing social relations. These are often so obvious that they require little explanation. However, felicity conditions in speech-acts are culture-specific and may include rhetorical and politeness devices that are not obvious to other cultures. Politeness behaviour in invitations, related to using appropriate language forms, is an important element in competent illocutionary performance. Leech contends that polite illocutions are likely to be seen as minimising the addressee's cost and maximising his/her benefits, and the opposite is true for the addresser. Politeness behaviour can also be further explained in the light of Brown and Levinson's face-saving theory. Many actions we perform with words are potential face-threatening acts, such as requests and invitations (Brown and Levinson). The addresser is thus often confronted with negative face wants and has to address them by applying Leech's principles, in which maximising the addressee's benefits is the dominant strategy to gain politeness. However, strategies to maximise the addressee's benefits can be culture-specific. This is further connected to the persuasive/rhetorical orientation. Based on Aristotle, the appeal from ethos emphasises the persuader's (host's) character and status or other social conventions which might oblige compliance. The appeal from pathos emphasises emotion/feelings (either positive or negative) in inducing the desired response. The appeal from logos emphasises reason and the logical consistency of the proposal with the ideas and motives of the persuadee (invitee). Moran and Stripp found that western cultures tend to have a logical orientation, while others such as Japanese and Chinese tend to be characterised by emotional or dogmatic orientations. In a similar manner, Chinese scholars seem to address ethos, logos and pathos at the same time, in particular the logos and pathos. These principles remain a well-accepted principle in Chinese writing theories. Li, for example, clearly explicates the persuasive principle in writing as qing li (the combination of the emotional and logical approaches). The explicitly preferred qing (feelings/emotions) can be seen as part of the Confucian values relating to harmony, consensus and relationship building as noted by Hofstede and Bond. The different rhetorical orientations are also further explored by Campbell. This difference may suggest that the preferred rhetorical orientations are also a key aspect underpinning competent illocutionary performance. For example in Chinese invitations, a stress on the emotional approach may validate behaviours such as repeating the invitation even after initial refusal. However, a stress on the logical orientation, such as in western cultures, may negate the validity of these politeness conditions. This clearly points out the necessity of understanding the criteria for competent performance across cultures. The felicity conditions of invitation in Euro-Australian culture require, first, that the potential host be in a legitimate position to offer hospitality, and second, that the potential guest be -- at least theoretically -- able and willing to accept. Thirdly, the locutionary form of politeness requires use of conventionally appropriate terms of address and wording. The illocutionary form requires that the host symbolically offer hospitality to the invitee without the imposition of charges or other demands. Furthermore, the implied benefit to the invitee would ideally be achieved though implied cost to the host (even if the invitee is addressed as if their presence constitutes the bestowal of a favour). Fourthly, depending on the nature of the relationship between the host and invitee, certain persuasive/rhetorical orientations are preferred over others (eg. an appeal to emotion may seem out of place in formal invitation). The initial invitation meets these criteria. Dr. Lin offers and Catherine declines, citing a plausible and legitimate reason for being unavailable. From Catherine's perspective, the felicity conditions for invitation are now redundant. She has already declined in a manner which makes it clear that she is socially obliged to be elsewhere. From a persuasive/rhetorical perspective, the first invitation was primarily based on an appeal from logos/reason. i.e. Dr. Lin did not know that Catherine had already committed herself to other plans and it would be reasonable to suppose that she might appreciate being invited to a social occasion. This was backed up by a secondary appeal from pathos/emotion, whereby Dr. Lin pointed out that it would be nice for the whole class to get together. However, the priority of attending a best friend's birthday-party over-rides both these appeals. In Euro-Australian culture, close personal friends enjoy greater social priority than classmates or more distant associates. For Dr. Lin, however, the politeness criteria for invitation were still applicable. From a Chinese cultural perspective, the illocutionary performance of invitation may require repetition of the offer, even if the initial approach has been declined. According to Zhu (Business Communication), in Chinese culture repeating invitations is an accepted ritual to indicate sincerity and hospitality. Thus in Dr. Lin's view the second approach is required to perform the illocutionary act competently. The persuasive appeal, however, has become oriented toward ethos, reflecting Chinese conventions pertaining to politeness behaviour. For Dr. Lin not to repeat the invitation might suggest that Catherine's presence was of merely casual concern. Therefore the sincerity of the invitation demanded the gesture of repetition, regardless of the logical grounds cited for the initial refusal. Unfortunately, Dr. Lin and Catherine perceive the second invitation in very different ways based on the illocutionary performance criteria of their respective cultures. For Catherine, the logical basis for her initial refusal renders Dr. Lin's performance incompetent, and creates uncertainty about his apparent motives. In Euro-Australian culture, the repeated invitation makes no logical sense, since a perfectly legitimate reason for declining has already been provided. Therefore the communicative action cannot be interpreted as an invitation. If it is, then it is performed in a culturally incompetent fashion which could legitimately be construed as pestering. Repeating an invitation which has already been declined may appear to be an emotional appeal. While an illocutionary invitation based on pathos conceivably may be competent in Euro-Australian culture, the only circumstances that it would occur in is between relatively close friends. The power-relations between Catherine, as student, and Dr. Lin, as tutor, precludes felicity in this case. Thus the same locutionary action is interpreted as two quite different illocutionary actions. This depends on the interpreter's culturally specific understanding of the social significance of the locution. Since Catherine's cultural conventions would implicitly deny the validity of a repeated invitation, the communicative action must be construed as something else. Catherine may have classified the repeated invitation as a minor issue of little consequence. However, when Dr. Lin called her up to invite her a third time, she interpreted the illocutionary act as harassment. From a contemporary Euro-Australian perspective, pestering may be irritating, but harassment is political in nature. Three factors lead Catherine to this conclusion. First, after two previous declinations, the third invitation could not fulfil the illocutionary performance criteria of a legitimate invitation. In particular, the persuasive/rhetorical orientation of the repeated appeals were not oriented toward logos, as befits the formality of the lecturer-student relation. Indeed, it was Dr. Lin's apparent attempt to approach Catherine in a non-formal manner (apparently oriented toward pathos rather than logos) which led her to this interpretation. Second, the fact that Dr. Lin' social status is higher than Catherine's introduced the problem of the implicit power-relations in the discourse. For Catherine, the third invitation was intrusive and pushy, and it seemed that her explanations had been ignored. The evening call demanded that she re-engage in the discourse of day-time student-tutor power-relations. Since she is subordinate to Dr. Lin, other strategies through which she might have asserted her rights may have carried the risk of subsequent disfavour. However, she obviously resented what she perceived as an attempt to inappropriately use status to interfere with her personal affairs and sought out higher authority to rectify the situation, hence the complaint of harassment made to the Dean. Ironically, Dr. Lin's third invitation in the evening may well have been intended to reduce the social distance between himself and Catherine created by workplace space-time power-relations. For Dr. Lin, the first invitation expressed the illocutionary intent. The second call made sure that the invitee was made to feel assured of the sincerity of the invitation, and the third ring expressed the would-be host's appreciation. Establishing a host-guest relationship is a key illocutionary function in Chinese invitation. Note though, that there may also be a 'face' consideration here. Dr. Lin attempts to facilitate Catherine's attendance by pointing out that it would be acceptable to attend for a brief period. This suggests a re-emphasis on the orientation to logos, since it points out a compromise which allows Catherine to attend both parties. It also allowed Dr. Lin to save 'face' by not having his invitation totally disregarded. However, it failed as an illocutionary performance because the felicity conditions for polite invitation had already been violated as far as Catherine was concerned, even though they remained intact throughout for Dr. Lin. In conclusion, it can be seen from the above analysis of the communication breakdown that persuasive orientations and politeness principles are interrelated and culturally sensitive. Euro-Australian culture stresses the logical orientation in illocutionary performance whereas Chinese culture seems to emphasise both the logical and emotional approaches. Without a recognition of this difference, specific politeness behaviours in intercultural invitations can lead to illocutionary incompetence. This has been exemplified by Catherine's misconstrual of Dr. Lin's intended invitation-performance as harassment. Therefore in intercultural communication, one ought not to judge a speech act such as an invitation based on one's own culture's felicity conditions. First and foremost, a basic understanding of persuasive orientations between cultures is essential. With appropriate understanding of these principles one can avoid misinterpreting the intent of the addresser, thus overcoming barriers in intercultural communication. Specifically, further appreciation of the interplay between rhetorical orientation, politeness codes and felicity conditions in illocutionary performances in different cultures is required for a fuller comprehension of potential cross-cultural incompetence. With this in mind, greater tolerance can be achieved, and intercultural competence enhanced. References Aristotle. Aristotle on Rhetoric: A Theory of Civic Discourse. Trans. George A. Kennedy. New York: Oxford UP, 1991. Austin, John. L. How to Do Things with Words. New York: Oxford UP, 1962. Brown, Penelope, and Stephen C. Levinson. Politeness: Some Universals in Language Usage. Cambridge, UK: Cambridge UP, 1987. Campbell, Charles. P. "Rhetorical Ethos: A Bridge between High-Context and Low-Context Cultures? The Cultural Context in Business Communication. Eds. Susanne Niemeier, Charles P. Campbell and René Dirven. Philadelphia: John Benjamins, 1998. 31-47. Cullen, Johnathan. Saussure. 2nd ed. London: Fontana, 1985. Ge Gao, and S. Ting-Toomey. Communicating Effectively with the Chinese. Thousand Oaks: Sage, 1998. Hall, E. T. Beyond Culture. Garden City, NY: Anchor, 1977. Hofstede, G., and M. H. Bond. "The Confucius Connection: From Cultural Roots to Economic Growth." Organisational Dynamics 16.4 (1988): 4-21. Kaplan, R. B. "Cultural Thought Patterns in Inter-Cultural Education." Language Learning 16 (1966): 1-20. Leech, Geoffery. Principles of Pragmatics. New York: Longman, 1983. Li Xiaoming. "Good Writing" in Cross-Cultural Context. Albany, NY: State U of New York P, 1996. Moran, R. T., and W. G. Stripp. Successful International Business Negotiations. Houston: Gulf, 1991. Searle, John R. Speech Acts: An Essay in the Philosophy of Language. Cambridge, UK: Cambridge UP, 1969. Young, Linda Wai Ling, ed. Crosstalk and Culture in Sino-American Communication. Cambridge, UK: Cambridge UP, 1994. Zhu Yunxia. Business Communication in China. New York: Nova Science Publishers, 1999. ---. Structural Moves Reflected in English and Chinese Sales Letters. Discourse Studies (In Press). Citation reference for this article MLA style: Zhu Yunxia, Peter Thompson. "Invitation or Sexual Harassment? An Analysis of an Intercultural Communication Breakdown." M/C: A Journal of Media and Culture 3.4 (2000). [your date of access] <http://www.api-network.com/mc/0008/invitation.php>. Chicago style: Zhu Yunxia, Peter Thompson, "Invitation or Sexual Harassment? An Analysis of an Intercultural Communication Breakdown," M/C: A Journal of Media and Culture 3, no. 4 (2000), <http://www.api-network.com/mc/0008/invitation.php> ([your date of access]). APA style: Zhu Yunxia, Peter Thompson. (2000) Invitation or sexual harassment? An analysis of an intercultural communication breakdown. M/C: A Journal of Media and Culture 3(4). <http://www.api-network.com/mc/0008/invitation.php> ([your date of access]).

Sometimes a particular concept—a simple term—is the spark to a series of ideas. It might be ostentatious and perhaps hubristic that the editors of an issue on persona might imagine that their choice of the term persona has provided this intellectual spark. Fully aware of that risk, we want to announce that it has. The response to the call for papers related to persona was our first sign that something special was being initiated. The sheer number and interdisciplinary breadth of the abstracts and ultimate submissions was evidence that the term ‘persona’ was the catalyst to an explosion of ideas. As the responses flowed into the journal and to us, we became aware of the meme-like qualities of the many interpretations and history of the term, each with its own idiosyncratic coding of patterned similarity. The reality of this development is that it was not entirely unexpected. The editors have been developing the concept of persona and persona studies over the past four years, and persona studies has emerged from a congruence in our collective research interests as an interdisciplinary investigation of the presentation of the self in the contemporary moment. Together, we have been involved in the development of the Persona Celebrity Publics Research Group (PCP) at Deakin University. Within that group, we have concentrated ourselves in the Persona Research cluster, made up of a group of 15 or so academics along with another smaller group from other institutions. Emerging from our work is the forthcoming book entitled Persona Studies: Celebrity, Identity, and the Transformation of Public Culture (forthcoming Wiley 2015). Both the book and the research group are intent on exploring what has been altering in our worlds, our cultures, and our communities that make us think the new intensified play of the personal in public needs closer scrutiny. The impetus for us as a team of scholars is quite clearly linked to the uses of online culture and how greater aspects of our lives are now involved in public displays, mediated displays, and a peculiar new blend of interpersonal and presentational constructions of identities and selves. Persona as a specific area of inquiry has emerged from the close study of the public self. Its immediate intellectual past has its strongest links with research on celebrity. In the Celebrity Studies Reader collection, Marshall began forming the idea that a new public self was emerging through new media (New Media). In subsequent work, Marshall identifies celebrity culture as one of the pedagogic sources for how the wider population presented itself in online culture and social media (Marshall, Promotion). Barbour and Marshall expanded their thinking about the presentation of the self through a closer study of online academic persona and the different strategic ways individuals were managing and building reputations and prestige through these techniques. Terms such as the ‘comprehensive,’ ’networked’, and ‘uncontained’ self, mapped the various kinds of public personalities that were emerging through the most prominent academics (Barbour and Marshall). In a similar vein, Barbour’s research has looked closely at the online and public personas that fringe artists—specifically tattoo artists, craftivists, performance poets and street artists—produce and maintain in the contemporary moment (Hiding; Finding). Her work has advanced the concepts of “registers of performance” (Registers), where a closer analysis of how the personal, the professional, and sometimes the intimate registers are constructed and deployed to produce a public persona that demonstrates ‘artistness’. By analysing persona through registers of performance, Barbour is able to differentiate between the types of identity building activity that occurs online. This provides insight into the ways that impression management occurs in spaces that suffer from context collapse due to the intersection of friends, family, fans, and followers. Moore’s work (Hats; Magic; Invigorating) on the player’s assembly of a networked online ‘gamer’ persona considers the intersection of social media and video game culture and contributes analysis of the affective dimensions of player-oriented game objects and their public curation and display. His recent research visualising Twitter and Flickr data (Screenshots, forthcoming) advances an understanding of the accumulation and online presentation of the self through digital game artefacts, specifically video game screenshots. He is currently researching the interaction of social media activity, reputation management, and everyday identity ‘play’ within public game cultures and the larger dynamics of production and consumption of games and play in the video game industry. Most recently, Marshall called for what he titled a “persona studies manifesto”: the public presentation of the self demands a more extensive analysis of the play and deployment of persona in contemporary culture. Beyond popular culture, the development of reputation and persona and its intersection with online culture especially needs to be explored in those professions, disciplines and activities where this form of investigation has never been attempted (Marshall, Persona Studies). The initiative of persona studies then is in some ways turning the cultural studies’ approach to the study of the audience on its head: it is a study of agency and the processes by which agency has been individualized and assembled across contemporary culture, but highly privileged in online culture (Marshall, Personifying). Persona studies involves a close investigation of the personalized and negotiated presentation of the self. So, what is persona? The articles here assume different, but connected, understandings of the term, each with levels of deference to writers such as Jung, Goffman, Butler, and Foucault, along with some expected allusions to the ancient Greeks and Romans who coined the term. The Greek origins identify that persona is a mask and derived from performance and acting. From Hannah Arendt’s reading of the Greeks this mask of public identity was not seen in a derogatory way; rather it was natural to assume a public/political persona that was quite removed from the private and home sphere. A political persona defined by citizenry was a clearly conscious separation from the household of activity. Jung’s take on persona is that it was designed for collective experience and for the outside world and therapy would lead to an understanding of the individual that delved beneath the persona. The resurgence in interest in Goffman’s dramaturgical analogy allows us to consider persona as an everyday performance, where the purpose of the presentation of self is to convince the audience (and at times, the performer) that the performance is genuine and authentic. All of us know what it is like to act in a role, to wear a uniform or costume, to create a profile. More than a few of us know what it is to suffer through the ‘individualising’ categories of a social networking sign-up survey that do not adequately account for distinctions. Persona is all these things, or rather, through the various everyday activities of our work, social, and online selves we contribute to the accretion of the identity at the base of its structure. Persona functions like the construct or automated script that we assemble to interact with the world with on our behalf. This involves the technologies of computation and mediation and their interfaces that function to automate, produce and filter communication with us; email, blogs, Twitter accounts, and so on. These golems interconnect and can interact on their own in unpredictable ways on our behalf; connecting our Facebook account to a product, brand or petition; using Google as a portal to login into other web enabled services; or authorising an app to record our location. Then there are the traces that we leave scattered across digital networks, intranets, hard drives, and lost USB memory sticks, from scattered collections of digital photos to the contact lists of our mobile devices and the ‘achievements’ in our online gaming profiles. Persona can also be something that happens to us, as friends tag unflattering images via Facebook, or another Twitter user publicly addresses us with a unwanted, or unwarranted commentary, using the ‘@’ and the ‘#’ functions. We have an extensive degree of control over the ways we assemble ourselves online and yet the contemporary experience is one of constant negotiation with forces that seeks to disavow their responsibilities to us, and maximise the limitations under which we can act. Our personas serve as a buffer to these forces. We can strategically assemble our persona to participate in, influence and use to our advantage to transmit messages across the network and communicate a mediated form of ourselves. The many ways to account persona stands as a primary and apparently Sisyphean task for persona studies: no sooner than when we might assemble a complete topology of the many accounts, traditions, domains, methodologies and theories for account of for the self, we will have arrived at possibly entirely new way of conceptualising the presentation of online persona through some post-Facebook, Oculus Rift, or Google Glass augmented reality experience. One of the challenges of persona studies will be to provide a series of methodological and theoretical tools, as well as a common touchstone from which multiple perspectives may converge around the meme-like qualities of this dramatic term. It will be necessary to consider the future of the presentation of the self, as much as the past accounts for the understanding of the self and its compositions. In the contemporary moment we consider a series of common currents and features of the iterations of persona with which we might begin this endeavour. The collective objective of the ‘persona’ theme edition is to coalesce around the emerging significance of the public self, and to map that activity within disciplinary traditions, historical precedents and the cultural and technological predispositions that have made this kind of reading of the contemporary world valuable, important, and ultimately, sensible. This collection of articles on persona is innovative in terms of the diversity of issues it tackles through the term. Given the massive change in public identity that we have identified as an elemental part of online culture, it is not surprising that social media and online constructions of persona figure prominently throughout the issue. However, we are also pleased to include papers that consider fictional performances from both television and film and even character studies of public figures. Marshall’s feature article for the edition continues his theorisation of persona. Seriality is identified as one of the ways that a consistency of persona is developed and the article charts the usefulness in analogizing how the construction of a serial character or ‘personnage’ for an actor/performer provides insights into the relationship between the person and persona in other settings that are emerging in the contemporary moment. In ‘Darkly Dreaming (in) Authenticity: The Self/Persona Opposition in Dexter,’ Glenn D'Cruz uses Dexter Morgan, the novelised serial killer and Showtime TV anti-hero to examine the connections between self and persona and the discourse of authenticity. D’Cruz foresees a series of challenges for persona studies and considers key concerns ahead, in terms of the critical vocabulary and scholarly agenda and addresses the need for critical genealogy of the term ‘persona’. Talia Morag, in ‘Persons and Their Personas: Living with Yourself’, considers the tensions identified in the persona of the private domain, and examines the patterns of social interaction that work to affect an ‘endorsed’ private persona, compared to those patterns classified as ‘hidden’. She frames the negotiation of these tensions as a move to better understand the sphere of the private self, as well as the those strains which arise on the private persona and the grounds from which they come to occupy our time. Together these two approaches predict the convergence of the private, the performed and the public persona which occupies Neil Henderson’s ‘The Contingency of Online Persona and Its Tension with Relationship Development’. Henderson’s engagement with the dimensions of online persona in the short film, Noah, takes a position at the crossroads between Marshall’s celebrity-inscribed approach to persona studies and the application of actor-network theory in order to map the potential pitfalls of identity management through ubiquitous technologies and broader critical questions about the play of our online selves in the everyday. Moving to the multi-user virtual environment of Second Life, Lesley Procter draws on the symbolic interactionist theories of social identity and the role of the avatar in ‘A Mirror without a Tain: Personae, Avatars, and Selves in a Multi-User Virtual Environment’. Procter’s contribution to persona studies highlights the actual and conceptual mirroring involved in the sense of the self involved in the interaction with others online. Taina Bucher’s ‘About a Bot: Hoax, Fake, Performance Art’ is a revealing examination of the Twitter bot phenomenon. Bucher’s case study on ‘bot fakeness’ considers the automation and performance of persona and the interactions and relationships between people and bots. Brady Robards, in ‘Digital Traces of the Persona through Ten Years of Facebook’, offers a critical reading of the Facebook ‘look back’ video creation application made to celebrate the social network’s ten year. As with Bucher and Proctor, Robards is concerned with the ways persona is created through highly mediated social networking platforms, where the agency of the individual is countered by the intervention of the software itself. Robards considers in particular two functions of Facebook: first as a site for the performance of life narratives, and second as a location for reflection on public and private disclosure. Taking a specific element of this idea of disclosure—the sharing of one’s legal name—as a starting point, Ellen Moll’s ‘What’s in a Nym?: Gender, Race, Pseudonymity, and the Imagining of the Online Persona’ is a study of the reactions of feminist and anti-racist bloggers in the ongoing battles over pseudonymity online. Moll’s contribution centres around current concerns with the ‘real name policies’ of social media and web-based platforms and services. What is at stake here in the negotiation between the individuals, technologies and institutions over the rights of self-determination and agency in the digital and online environments. Narrowing the focus to a single case study, Emma Maguire’s study of author website as a site of self-presentation in ‘Home, About, Shop, Contact: Constructing an Authorial Persona via the Author Website’ examines the authorial persona produced for consumption within literary markets. Framing of the authorial website as ‘automedial text’, rather than as direct representations of a pre-existing self, Maguire employs authorship theory to understand the website as a genre of persona performance and textuality. Shifting away from the focus on social media, this issue concludes with a trio of character studies, each of which involves a detailed and critical account of the dimensions of a public assembly of a persona. Nathan Farrell’s ‘From Activist to Entrepreneur: Peace One Day and the Changing Persona of the Social Campaigner’ is the first, and considers the ways that an individual manages his persona for different audiences. Farrell’s focus is Jeremy Gilley, a documentary filmmaker and peace campaigner, and the paper speaks to the dimensions of overlapping audiences connected to an articulation of a socially aware entrepreneurial persona. Sally Totman and Mat Hardy have a very different figure in their contribution as they examine the many different public personas of Libya’s Colonel Muammar Qaddafi. In ‘The Many Personas of Colonel Qaddafi’, Totman and Hardy interrogate the multiple aspects of Qaddafi’s construction as a brotherly revolutionary, philosopher, liberator, leader, and clown. The authors chart the progression of his often conflicted and chaotic legacy, and of this political, ideological and even messianic presentation of the self to the Western and Arab worlds. Anastasia Denisova, completes the triptych of persona case studies for this collection, with ‘How Vladimir Putin's Divorce Story Was Constructed and Received, or When the President Divorced His Wife and Married the Country Instead’. Denisova contends Vladimir Putin’s divorce is representative of the degree to which political and private persona are mediated and merged across often competing channels of communication. The analysis contends with online discourse, images, and texts, which reveal the extensive personification of politics in Putin’s public persona in an environment of reception by an audience which also consider the values and attributes of their own country as a national persona. Conclusion We have structured the narrative flow of articles in this issue on persona from the fictional through to the online transformations of the self and then even further into the analyses of the public and political dimensions that are part of the constitution of public selves. No doubt, you as a reader will see different connections and intersections and will play with what makes the idea of persona so meaningful and valuable in understanding the strategic construction of a public identity and so central to comprehending the contemporary moment. We invite you to engage with this further with the issue editors’ planned 2015 launch of a journal called Persona Studies. Until then, this issue of M/C Journal certainly represents the most comprehensive and, we think, interesting, collection of writing on persona as we explore the implications behind the mask of public identity. We hope the issue stimulates discussion and with that hope, we hope to hear from you.AcknowledgmentsThe editors would like to thank Alison Bennett for creating an original gif for the cover image of this issue. More of Bennett's work, including her augmented reality images of tattoos from the internationally acclaimed exhibition Shifting Skin, can be found at her website, alisonbennett.com.au.Thanks also to Trent Griffiths for his copy-editing assistance. References Arendt, Hannah. The Human Condition. Charles R. Walgreen Foundation Lectures. Chicago, Ill.: University of Chicago Press, 1958. Barbour, Kim. “Hiding in Plain Sight: Street Artists Online.” Platform Journal of Media and Communication. 5.1 (2013). Barbour, Kim. “Registers of Performance: Negotiating the professional, personal, and intimate.” MeCCSA 2014. Bournemouth, 8-10 Jan. 2014. Barbour, Kim. “Finding the Edge: Online persona creation by fringe artists.” Contemporary Publics International Symposium. 24-25 Feb. 2014. Barbour, Kim, and P. David Marshall. "The Academic Online: Constructing Persona through the World Wide Web." First Monday 17.9 (2012). ‹http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/viewArticle/3969/3292›. Goffman, Erving. The Presentation of Self in Everyday Life. USA: Anchor Books, 1959. Jung, Carl Gustav. Two Essays on Analytical Psychology. Bollingen Series. 2nd ed. Princeton, N.J.: Princeton University Press, 1966. Marshall, P. David. "New Media New Self, the Changing Power of the Celebrity." The Celebrity Culture Reader. Ed. P. David Marshall. London: Routledge, 2006. 634-44. Marshall, P. David. "The Promotion and Presentation of the Self: Celebrity as Marker of Presentational Media." Celebrity Studies 1.1 (2010): 35-48. Marshall, P. David. "Personifying Agency: The Public–Persona–Place–Issue Continuum." Celebrity Studies 4.3 (2013): 369-71.Marshall, P. David. "Persona Studies: Mapping the Proliferation of the Public Self." Journalism 15.2 (2014): 153-70. Marshall, P. David, Chris Moore and Kim Barbour, Persona Studies: Celebrity, Identity and the Transformation of Public Culture. Hoboken NJ: Wiley, forthcoming 2015. Moore, Chris. “Hats of Affect: A Study of Affect, Achievements and Hats in Team Fortress 2.” Game Studies 11 (2011). ‹http://gamestudies.org/1101/articles/moore›. Moore, Chris. “The Magic Circle and the Mobility of Play.” Convergence 17 (2011): 373-387. Moore, Chris. “Invigorating Play: The Role of Affect in Online Multiplayer FPS Game.” Guns, Grenades, and Grunts: First-Person Shooter Games. Ed. Gerald A. Voorhees, Josh Call, and Katie Whitlock. London: Continuum, 2012. 341-363. Moore, Chris. “Screenshots as Virtual Photography: Cybernetics, Remediation and Affect.” Advancing Digital Humanities. Ed. Paul Longley Arthur and Katherine Bode. Palgrave Macmillan. Forthcoming 2014. .

Story spreads out through time the behaviors or bodies – the shapes – a self has been or will be, each replacing the one before. Hence a story has before and after, gain and loss. It goes somewhere…Moreover, shape or body is crucial, not incidental, to story. It carries story; it makes story visible; in a sense it is story. Shape (or visible body) is in space what story is in time. (Bynum, quoted in Garland Thomson, 113-114) Drawing on Goffman’s classic work on stigma, research documenting the existence of discrimination and bias against individuals classified as obese goes back five decades. Since Cahnman published “The Stigma of Obesity” in 1968, other researchers have well documented systematic and growing discrimination against fat people (cf. Puhl and Brownell; Puhl and Heuer; Puhl and Heuer; Fikkan and Rothblum). While weight-based stereotyping has a long history (Chang and Christakis; McPhail; Schwartz), contemporary forms of anti-fat stigma and discrimination must be understood within a social and economic context of neoliberal healthism. By neoliberal healthism (see Crawford; Crawford; Metzel and Kirkland), I refer to the set of discourses that suggest that humans are rational, self-determining actors who independently make their own best choices and are thus responsible for their life chances and health outcomes. In such a context, good health becomes associated with proper selfhood, and there are material and social consequences for those who either unwell or perceived to be unwell. While the greatest impacts of size-based discrimination are structural in nature, the interpersonal impacts are also significant. Because obesity is commonly represented (at least partially) as a matter of behavioral choices in public health, medicine, and media, to “remain fat” is to invite commentary from others that one is lacking in personal responsibility. Guthman suggests that this lack of empathy “also stems from the growing perception that obesity presents a social cost, made all the more tenable when the perception of health responsibility has been reversed from a welfare model” (1126). Because weight loss is commonly held to be a reasonable and feasible goal and yet is nearly impossible to maintain in practice (Kassierer and Angell; Mann et al.; Puhl and Heuer), fat people are “in effect, asked to do the impossible and then socially punished for failing” (Greenhalgh, 474). In this article, I explore how weight-based stigma shaped the decisions of bariatric patients to undergo weight loss surgery. In doing so, I underline the work that emotion does in circulating anti-fat stigma and in creating categories of subjects along lines of health and responsibility. As well, I highlight how fat bodies are lived and negotiated in space and place. I then explore ways in which participants take up notions of time, specifically in regard to risk, in discussing what brought them to the decision to have bariatric surgery. I conclude by arguing that it is a dynamic interaction between the material, social, emotional, discursive, and the temporal that produces not only fat embodiment, but fat subjectivity “failed”, and serves as an impetus for seeking bariatric surgery. Methods This article is based on 30 semi-structured interviews with American bariatric patients. At the time of the interview, individuals were between six months and 12 years out from surgery. After obtaining Intuitional Review Board approval, recruitment occurred through a snowball sample. All interviews were audio-taped with permission and verbatim interview transcripts were analyzed by means of a thematic analysis using Dedoose (www.dedoose.com). All names given in this article are pseudonyms. This work is part of a larger project that includes two additional interviews with bariatric surgeons as well as participant-observation research. Findings Navigating Anti-Fat Stigma In discussing what it was like to be fat, all but one of the individuals I interviewed discussed experiencing substantive size-based stigma and discrimination. Whether through overt comments, indirect remarks, dirty looks, open gawking, or being ignored and unrecognized, participants felt hurt, angry, and shamed by friends, family, coworkers, medical providers, and strangers on the street because of the size of their bodies. Several recalled being bullied and even physically assaulted by peers as children. Many described the experience of being fat or very fat as one of simultaneous hypervisibility and invisibility. One young woman, Kaia, said: “I absolutely was not treated like a person … . I was just like this object to people. Just this big, you know, thing. That’s how people treated me.” Nearly all of my participants described being told repeatedly by others, including medical professionals, that their inability to lose weight was effectively a failure of the will. They found these comments to be particularly hurtful because, in fact, they had spent years, even decades, trying to lose weight only to gain the weight back plus more. Some providers and family members seemed to take up the idea that shame could be a motivating force in weight loss. However, as research by Lewis et al.; Puhl and Huerer; and Schafer and Ferraro has demonstrated, the effect this had was the opposite of what was intended. Specifically, a number of the individuals I spoke with delayed care and avoided health-facilitating behaviors, like exercising, because of the discrimination they had experienced. Instead, they turned to health-harming practices, like crash dieting. Moreover, the internalization of shame and blame served to lower a sense of self-worth for many participants. And despite having a strong sense that something outside of personal behavior explained their escalating body weights, they deeply internalized messages about responsibility and self-control. Danielle, for instance, remarked: “Why could the one thing I want the most be so impossible for me to maintain?” It is important to highlight the work that emotion does in circulating such experiences of anti-fat stigma and discrimination. As Fraser et al have argued in their discussion on fat and emotion, the social, the emotional, and the corporeal cannot be separated. Drawing on Ahmed, they argue that strong emotions are neither interior psychological states that work between individuals nor societal states that impact individuals. Rather, emotions are constitutive of subjects and collectivities, (Ahmed; Fraser et al.). Negative emotions in particular, such as hate and fear, produce categories of people, by defining them as a common threat and, in the process, they also create categories of people who are deemed legitimate and those who are not. Thus following Fraser et al, it is possible to see that anti-fat hatred did more than just negatively impact the individuals I spoke with. Rather, it worked to produce, differentiate, and drive home categories of people along lines of health, weight, risk, responsibility, and worth. In this next section, I examine the ways in which anti-fat discrimination works at the interface of not only the discursive and the emotive, but the material as well. Big Bodies, Small Spaces When they discussed their previous lives as very fat people, all of the participants made reference to a social and built environment mismatch, or in Garland Thomson’s terms, a “misfit”. A misfit occurs “when the environment does not sustain the shape and function of the body that enters it” (594). Whereas the built environment offers a fit for the majority of bodies, Garland Thomson continues, it also creates misfits for minority forms of embodiment. While Garland Thomson’s analysis is particular to disability, I argue that it extends to fat embodiment as well. In discussing what it was like to navigate the world as fat, participants described both the physical and emotional pain entailed in living in bodies that did not fit and frequently discussed the ways in which leaving the house was always a potential, anxiety-filled problem. Whereas all of the participants I interviewed discussed such misfitting, it was notable that participants in the Greater New York City area (70% of the sample) spoke about this topic at length. Specifically, they made frequent and explicit mentions of the particular interface between their fat bodies and the Metropolitan Transit Authority (MTA), and the tightly packed spaces of the city itself. Greater New York City area participants frequently spoke of the shame and physical discomfort in having to stand on public transportation for fear that they would be openly disparaged for “taking up too much room.” Some mentioned that transit seats were made of molded plastic, indicating by design the amount of space a body should occupy. Because they knew they would require more space than what was allotted, these participants only took seats after calculating how crowded the subway or train car was and how crowded it would likely become. Notably, the decision to not take a seat was one that was made at a cost for some of the larger individuals who experienced joint pain. Many participants stated that the densely populated nature of New York City made navigating daily life very challenging. In Talia’s words, “More people, more obstacles, less space.” Participants described always having to be on guard, looking for the next obstacle. As Candice put it: “I would walk in some place and say, ‘Will I be able to fit? Will I be able to manoeuvre around these people and not bump into them?’ I was always self-conscious.” Although participants often found creative solutions to navigating the hostile environment of both the MTA and the city at large, they also identified an increasing sense of isolation that resulted from the physical discomfort and embarrassment of not fitting in. For instance, Talia rarely joined her partner and their friends on outings to movies or the theater because the seats were too tight. Similarly, Decenia would make excuses to her husband in order to avoid social situations outside of the home: “I’d say to my husband, ‘I don’t feel well, you go.’ But you know what? It was because I was afraid not to fit, you know?” The anticipatory scrutinizing described by these participants, and the anxieties it produced, echoes Kirkland’s contention that fat individuals use the technique of ‘scanning’ in order to navigate and manage hostile social and built environments. Scanning, she states, involves both literally rapidly looking over situations and places to determine accessibility, as well as a learned assessment and observation technique that allows fat people to anticipate how they will be received in new situations and new places. For my participants, worries about not fitting were more than just internal calculation. Rather, others made all too clear that fat bodies are not welcome. Nina recalled nasty looks she received from other subway riders when she attempted to sit down. Decenia described an experience on a crowded commuter train in which the woman next to her openly expressed annoyance and disgust that their thighs were touching. Talia recalled being aggressively handed a weight loss brochure by a fellow passenger. When asked to contrast their experiences living in New York City with having travelled or lived elsewhere, participants almost universally described the New York as a more difficult place to live for fat people. However, the experiences of three of the Latinas that I interviewed troubled this narrative. Katrina felt that the harassment she received in her country of origin, the Dominican Republic, was far worse than what she now experienced in the New York Metropolitan Area. Although Decenia detailed painful experiences of anti-fat stigma in New York City, she nevertheless described her life as relatively “easy” compared to what it was like in her home country of Brazil. And Denisa contrasted her neighbourhood of East Harlem with other parts of Manhattan: “In Harlem it's different. Everybody is really fat or plump – so you feel a bit more comfortable. Not everybody, but there's a mix. Downtown – there's no mix.” Collectively, their stories serve as a reminder (see Franko et al.; Grabe and Hyde) to be suspicious of over determined accounts that “Latino culture” is (or people of colour communities in general are), more accepting of larger bodies and more resistant to weight-based stigma and discrimination. Their comments also reflect arguments made by Colls, Grosz, and Garland Thomson, who have all pointed to the contingent nature between space and bodies. Colls argue that sizing is both a material and an emotional process – what size we take ourselves to be shifts in different physical and emotional contexts. Grosz suggests that there is a “mutually constitutive relationship between bodies and cities” – one that, I would add, is raced, classed, and gendered. Garland Thomson has described the relationship between bodies and space/place as “a dynamic encounter between world and flesh.” These encounters, she states, are always contingent and situated: “When the spatial and temporal context shifts, so does the fit, and with it meanings and consequences” (592). In this sense, fat is materialized differently in different contexts and in different scales – nation, state, city, neighbourhood – and the materialization of fatness is always entangled with raced, classed, and gendered social and political-economic relations. Nevertheless, it is possible to draw some structural commonalities between divergent parts of the Greater New York City Metropolitan Area. Specifically, a dense population, cramped physical spaces, inaccessible transportation and transportation funding cuts, social norms of fast paced life, and elite, raced, classed, and gendered norms of status and beauty work to materialize fatness in such a way that a ‘misfit’ is often the result for fat people who live and/or work in this area. And importantly, misfitting, as Garland Thomson argues, has consequences: it literally “casts out” when the “shape and function of … bodies comes into conflict with the shape and stuff of the built world” (594). This casting out produces some bodies as irrelevant to social and economic life, resulting in segregation and isolation. To misfit, she argues, is to be denied full citizenship. Responsibilising the Present Garland Thomson, discussing Bynum’s statement that “shape carries story”, argues the following: “the idea that shape carries story suggests … that material bodies are not only in the spaces of the world but that they are entwined with temporality as well” (596). In this section, I discuss how participants described their decisions to get weight loss surgery by making references to the need take responsibility for health now, in the present, in order to avoid further and future morbidity and mortality. Following Adams et al., I look at how the fat body is lived in a state of constant anticipation – “thinking and living toward the future” (246). All of the participants I spoke with described long histories of weight cycling. While many managed to lose weight, none were able to maintain this weight loss in the long term – a reality consistent with the medical fact that dieting does not produce durable results (Kassirer and Angell; Mann et al.; Puhl and Heuer). They experienced this inability as not only distressing, but terrifying, as they repeatedly regained the lost weight plus more. When participants discussed their decisions to have surgery, they highlighted concerns about weight related comorbidities and mobility limitations in their explanations. Consistent then with Boero, Lopez, and Wadden et al., the participants I spoke with did not seek out surgery in hopes of finding a permanent way to become thin, but rather a permanent way to become healthy and normal. Concerns about what is considered to be normative health, more than simply concerns about what is held to be an appropriate appearance, motivated their decisions. Significantly, for these participants the decision to have bariatric surgery was based on concerns about future morbidity (and mortality) at least as much, if not more so, than on concerns about a current state of ill health and impairment. Some individuals I spoke with were unquestionably suffering from multiple chronic and even life threatening illnesses and feared they would prematurely die from these conditions. Other participants, however, made the decision to have bariatric surgery despite the fact that they had no comorbidities whatsoever. Motivating their decisions was the fear that they would eventually develop them. Importantly, medial providers explicitly and repeatedly told all of these participants that lest they take drastic and immediate action, they would die. For example: Faith’s reproductive endocrinologist said: “you’re going to have diabetes by the time you’re 30; you’re going to have a stroke by the time you’re 40. And I can only hope that you can recover enough from your stroke that you’ll be able to take care of your family.” Several female participants were warned that without losing weight, they would either never become pregnant or they would die in childbirth. By contrast, participants stated that their bariatric surgeons were the first providers they had encountered to both assert that obesity was a medical condition outside of their control and to offer them a solution. Within an atmosphere in which obesity is held to be largely or entirely the result of behavioural choices, the bariatric profession thus positions itself as unique by offering both understanding and what it claims to be a durable treatment. Importantly, it would be a mistake to conclude that some bariatric patients needed surgery while others choose it for the wrong reasons. Regardless of their states of health at the time they made the decision to have surgery, the concerns that drove these patients to seek out these procedures were experienced as very real. Whether or not these concerns would have materialized as actual health conditions is unknown. Furthermore, bariatric patients should not be seen as having been duped or suffering from ‘false consciousness.’ Rather, they operate within a particular set of social, cultural, and political-economic conditions that suggest that good citizenship requires risk avoidance and personal health management. As these individuals experienced, there are material and social consequences for ‘failing’ to obtain normative conceptualizations of health. This set of conditions helps to produce a bariatric patient population that includes both those who were contending with serious health concerns and those who feared they would develop them. All bariatric patients operate within this set of conditions (as do medical providers) and make decisions regarding health (current, future, or both) by using the resources available to them. In her work on the temporalities of dieting, Coleman argues that rather than seeing dieting as a linear and progressive event, we might think of it instead a process that brings the future into the present as potential. Adams et al suggest concerns about potential futures, particularly in regard to health, are a defining characteristic of our time. They state: “The present is governed, at almost every scale, as if the future is what matters most. Anticipatory modes enable the production of possible futures that are lived and felt as inevitable in the present, rendering hope and fear as important political vectors” (249). The ability to act in the present based on potential future risks, they argue, has become a moral imperative and a marker of proper of citizenship. Importantly, however, our work to secure the ‘best possible future’ is never fully assured, as risks are constantly changing. The future is thus always uncertain. Acting responsibly in the present therefore requires “alertness and vigilance as normative affective states” (254). Importantly, these anticipations are not diagnostic, but productive. As Adams et al state, “the future arrives already formed in the present, as if the emergency has already happened…a ‘sense’ of the simultaneous uncertainty and inevitability of the future, usually manifest in entanglements of fear and hope” (250). It is in this light, then, that we might see the decision to have bariatric surgery. For these participants, their future weight-related morbidity and mortality had already arrived in the present and thus they felt they needed to act responsibly now, by undergoing what they had been told was the only durable medical intervention for obesity. The emotions of hope, fear, anxiety and I would suggest, hatred, were key in making these decisions. Conclusion Medical, public health, and media discourses frame obesity as an epidemic that threatens to bring untold financial disaster and escalating rates of morbidity and mortality upon the nation state and the world at large. As Fraser et al argue, strong emotions (such hatred, fear, anxiety, and hope), are at the centre of these discourses; they construct, circulate, and proliferate them. Moreover, they create categories of people who are deemed legitimate and categories of others who are not. In this context, the participants I spoke with were caught between a desire to have fatness understood as a medical condition needing intervention; the anti-fat attitudes of others, including providers, which held that obesity was a failure of the will and nothing more; their own internalization of these messages of personal responsibility for proper behavioural choices, and, the biologically intractable nature of fatness wherein dieting not only fails to reduce weight in the vast majority of cases but results, in the long term, in increased weight gain (Kassirer and Angell; Mann et al.; Puhl and Heuer). Widespread anxiety and embarrassment over and fear and hatred of fatness was something that the individuals I interviewed experienced directly and which signalled to them that they were less than human. Their desire for weight loss, therefore was partially a desire to become ‘normal.’ In Butler’s term, it was the desire for a ‘liveable life. ’A liveable life, for these participants, included a desire for a seamless fit with the built environment. The individuals I spoke with were never more ashamed of their fatness than when they experienced a ‘misfit’, in Garland Thomson’s terms, between their bodies and the material world. Moreover, feelings of shame over this disjuncture worked in tandem with a deeply felt, pressing sense that something must be done in the present to secure a better health future. The belief that bariatric surgery might finally provide a durable answer to obesity served as a strong motivating factor in their decisions to undergo bariatric surgery. By taking drastic action to lose weight, participants hoped to contest stigmatizing beliefs that their fat bodies reflected pathological interiors. Moreover, they sought to demonstrate responsibility and thus secure proper subjectivities and citizenship. In this sense, concerns, anxieties, and fears about health cannot be disentangled from the experience of anti-fat stigma and discrimination. Again, anti-fat bias, for these participants, was more than discursive: it operated through the circulation of emotion and was experienced in a very material sense. The decision to have weight loss surgery can thus be seen as occurring at the interface of emotion, flesh, space, place, and time, and in ways that are fundamentally shaped by the broader social context of neoliberal healthism. AcknowledgmentI am grateful to the anonymous reviewers of this article for their helpful feedback on earlier version. References Adams, Vincanne, Michelle Murphy, and Adele E. Clarke. “Anticipation: Technoscience, Life, Affect, Temporality.” Subjectivity 28.1 (2009): 246-265. Ahmed, Sara. “Affective Economies.” Social Text 22.2 (2004): 117-139 Boero, Natalie. Killer Fat: Media, Medicine, and Morals in the American "Obesity Epidemic". New Brunswick: Rutgers University Press, 2012. Butler, Judith. Undoing Gender. New York: Routledge, 2004. Bynum, Caroline Walker. 1999. Jefferson Lecture in the Humanities. National Endowment for the Humanities. Washington, DC, 1999. Cahnman, Werner J. “The Stigma of Obesity.” The Sociological Quarterly 9.3 (1968): 283-299. Chang, Virginia W., and Nicholas A. Christakis. “Medical Modeling of Obesity: A Transition from Action to Experience in a 20th Century American Medical Textbook.” Sociology of Health & Illness 24.2 (2002): 151-177. Coleman, Rebecca. “Dieting Temporalities: Interaction, Agency and the Measure of Online Weight Watching.” Time & Society 19.2 (2010): 265-285. Colls, Rachel. “‘Looking Alright, Feeling Alright:’ Emotions, Sizing, and the Geographies of Women’s Experience of Clothing Consumption.” Social & Cultural Geography 5.4 (2004): 583-596. Crawford, Robert. “You Are Dangerous to Your Health: The Ideology and Politics of Victim Blaming.” International Journal of Health Services 7.4 (1977): 663-680. ———. “Health as a Meaningful Social Practice.: Health 10.4 (2006): 401-20. Dedoose. Computer Software. n.d. Franko, Debra L., Emilie J. Coen, James P. Roehrig, Rachel Rodgers, Amy Jenkins, Meghan E. Lovering, Stephanie Dela Cruz. “Considering J. Lo and Ugly Betty: A Qualitative Examination of Risk Factors and Prevention Targets for Body Dissatisfaction, Eating Disorders, and Obesity in Young Latina Women.” Body Image 9.3 (2012), 381-387. Fikken, Janna J., and Esther D. Rothblum. “Is Fat a Feminist Issue? Exploring the Gendered Nature of Weight Bias.” Sex Roles 66.9-10 (2012): 575-592. Fraser, Suzanne, JaneMaree Maher, and Jan Wright. “Between Bodies and Collectivities: Articulating the Action of Emotion in Obesity Epidemic Discourse.” Social Theory & Health 8.2 (2010): 192-209. Garland Thomson, Rosemarie. “Misfits: A Feminist Materialist Disability Concept.” Hypatia 26.3 (2011): 591-609. Goffman, Erving. Stigma: Notes on the Management of Spoiled Identity. New York: Simon & Schuster, 1963. Grabe, Shelly, and Janet S. Hyde. “Ethnicity and Body Dissatisfaction among Women in the United States: A Meta-Analysis.” Psychological Bulletin 132.2 (2006): 622. Greenhalgh, Susan. “Weighty Subjects: The Biopolitics of the U.S. War on Fat.” American Ethnologist 39.3 (2012): 471-487. Grosz, Elizabeth A. “Bodies-Cities.” Feminist Theory and the Body: A Reader, eds. Janet Price and Margrit Shildrick. New York: Routledge, 1999. 381-387. Guthman, Julie. “Teaching the Politics of Obesity: Insights into Neoliberal Embodiment and Contemporary Biopolitics.” Antipode 41.5 (2009): 1110-1133. Kassirer, Jerome P., and M. Marcia Angell. “Losing Weight: An Ill-Fated New Year's Resolution.” The New England Journal of Medicine 338.1 (1998): 52. Kirkland, Anna. “Think of the Hippopotamus: Rights Consciousness in the Fat Acceptance Movement.” Law & Society Review 42.2 (2008): 397-432. Lewis, Sophie, Samantha L. Thomas, R. Warwick Blood, David Castle, Jim Hyde, and Paul A. Komesaroff. “How Do Obese Individuals Perceive and Respond to the Different Types of Obesity Stigma That They Encounter in Their Daily Lives? A Qualitative Study.” Social Science & Medicine 73.9 (2011): 1349-56. López, Julia Navas. “Socio-Anthropological Analysis of Bariatric Surgery Patients: A Preliminary Study.” Social Medicine 4.4 (2009): 209-217. McPhail, Deborah. “What to Do with the ‘Tubby Hubby?: ‘Obesity,’ the Crisis of Masculinity, and the Nuclear Family in Early Cold War Canada. Antipode 41.5 (2009): 1021-1050. Mann, Traci, A. Janet Tomiyama, Erika Westling, Ann-Marie Lew, Barbara Samuels, and Jason Chatman. “Medicare’s Search for Effective Obesity Treatments.” American Psychologist 62.3 (2007): 220-233. Metzl, Jonathan. “Introduction: Why ‘Against Health?’” Against Health: How Health Became the New Morality, eds. Jonathan Metzl and Anna Kirkland. New York: NYU Press, 2010. 1-14. Puhl, Rebecca M. “Obesity Stigma: Important Considerations for Public Health.” American Journal of Public Health 100.6 (2010): 1019-1028.———, and Kelly D. Brownell. “Psychosocial Origins of Obesity Stigma: Toward Changing a Powerful and Pervasive Bias.” Obesity Reviews 4.4 (2003): 213-227. ——— and Chelsea A. Heuer. “The Stigma of Obesity: A Review and Update.” Obesity 17.5 (2009): 941-964. Schafer, Markus H., and Kenneth F. Ferraro. “The Stigma of Obesity: Does Perceived Weight Discrimination Affect Identity and Physical Health?” Social Psychology Quarterly 74.1 (2011): 76-97. Schwartz, H. Never Satisfied: A Cultural History of Diets, Fantasies, and Fat. New York: Anchor Books, 1986. Wadden, Thomas A., David B. Sarwer, Anthony N. Fabricatore, LaShanda R. Jones, Rebecca Stack, and Noel Williams. “Psychosocial and Behavioral Status of Patients Undergoing Bariatric Surgery: What to Expect before and after Surgery.” The Medical Clinics of North America 91.3 (2007): 451-69. Wilson, Bianca. “Fat, the First Lady, and Fighting the Politics of Health Science.” Lecture. The Graduate Center of the City University of New York. 14 Feb. 2011.

Background: Reperfusion following ischemia can lead to more injuries than ischemia itself especially in diabetic patients. The aim of this study was to evaluate the effect of dexmedetomidine on ischemia-reperfusion injury (IRI) in rats with have hepatic IRI and diabetes mellitus. Methodology: Twenty-eight Wistar Albino rats were randomised into four groups as control (C), diabetic (DC), diabetic with hepatic ischemia-reperfusion injury (DIR), and diabetic but administered dexmedetomidine followed by hepatic IRI (DIRD) groups. Hepatic tissue samples were evaluated histopathologically by semiquantitative methods. Malondialdehyde (MDA), superoxide dismutase (SOD), glutathion s-transpherase (GST), and catalase (CAT) enzyme levels were investigated in liver and kidney tissues as oxidative state parameters. Results: In Group DIR; hepatocyte degeneration, sinusoidal dilatation, pycnotic nucleus, and necrotic cells were found to be more in rat hepatic tissue; while mononuclear cell infiltration was higher in the parenchyme. MDA levels were significantly lower; but SOD levels were significantly higher in Group DIRD with regard to Group DIR. In the IRI induced diabetic rats’ hepatic and nephrotic tissues MDA levels, showing oxidative injury, were found to be lower. SOD levels, showing early antioxidant activity, were higher. Conclusion: The enzymatic findings of our study together with the hepatic histopathology indicate that dexmedetomidine has a potential role to decrease IRI. Key words: Hepatic ischemia reperfusion injury; Diabetes mellitus; Dexmedetomidine; Rat; MDA; SOD Citation: Sezen SC, Işık B, Bilge M, Arslan M, Çomu FM, Öztürk L, Kesimci E, Kavutçu M. Effect of dexmedetomidine on ischemia-reperfusion injury of liver and kidney tissues in experimental diabetes and hepatic ischemia-reperfusion injury induced rats. Anaesth Pain & Intensive Care 2016;20(2):143-149 Received: 21 November 2015; Reviewed: 10, 24 December 2015, 9, 10 June 2016; Corrected: 12 December 2015; Accepted: 10 June 2016 INTRODUCTİON Perioperative acute tissue injury induced by ischemia-reperfusion is a comman clinical event caused by reduced blood supply to the tissue being compromised during major surgery. Ischemia leads to cellular injury by depleting cellular energy deposits and resulting in accumulation of toxic metabolites. The reperfusion of tissues that have remained in ischemic conditions causes even more damage.1 Furthermore hepatic ischemia-reperfusion injury (IRI) demonstrates a strong relationship with peri-operative acute kidney injury.2 The etiology of diabetic complications is strongly associated with increased oxidative stress (OS). Diabetic patients are known to have a high risk of developing OS or IRI which results with tissue failure.3 The most important role in ischemia and reperfusion is played by free oxygen radicals.1 In diabetes, characterized by hyperglycemia, even more free oxygen radicals are produced due to oxidation of glucose and glycosylation of proteins.3 The structures which are most sensitive to free oxygen radicals in the cells are membrane lipids, proteins, nucleic acids and deoxyribonucleic acids.1 It has been reported that endogenous antioxidant enzymes [superoxide dismutase (SOD), glutathion s-transpherase (GST), catalase (CAT)] play an important role to alleviate IRI.4-8 Also some pharmacological agents have certain effects on IRI.1 The anesthetic agents influence endogenous antioxidant systems and free oxygen radical formation.9-12 Dexmedetomidine is a selective α-2 adrenoceptor agonist agent. It has been described as a useful and safe adjunct in many clinical applications. It has been found that it may increase urine output by considerably redistributing cardiac output, inhibiting vasopressin secretion and maintaining renal blood flow and glomerular filtration. Previous studies demonstrated that dexmedetomidine provides protection against renal, focal cerebral, cardiac, testicular, and tourniquet-induced IRI.13-18 Arslan et al observed that dexmedetomidine protected against lipid peroxidation and cellular membrane alterations in hepatic IRI, when given before induction of ischemia.17 Si et al18 demonstrated that dexmedetomidine treatment results in a partial but significant attenuation of renal demage induced by IRI through the inactivation of JAK/STAT signaling pathway in an in vivo model. The efficacy of the dexmedetomidine for IRI in diabetic patient is not resarched yet. The purpose of this experimental study was to evaluate the biochemical and histological effects of dexmedetomidine on hepatic IRI in diabetic rat’s hepatic and renal tissue. METHODOLOGY Animals and Experimental Protocol: This study was conducted in the Physiology Laboratory of Kirikkale University upon the consent of the Experimental Animals Ethics Committee of Kirikkale University. All of the procedures were performed according to the accepted standards of the Guide for the Care and Use of Laboratory Animals. In the study, 28 male Wistar Albino rats, weighing between 250 and 300 g, raised under the same environmental conditions, were used. The rats were kept under 20-21 oC at cycles of 12-hour daylight and 12-hour darkness and had free access to food until 2 hours before the anesthesia procedure. The animals were randomly separated into four groups, each containing 7 rats. Diabetes was induced by a single intraperitoneal injection of streptozotocin (Sigma Chemical, St. Louis, MO, USA) at a dose of 65 mg/kg body weight. The blood glucose levels were measured at 72 hrs following this injection. Rats were classified as diabetic if their fasting blood glucose (FBG) levels exceeded 250 mg/dl, and only animals with FBGs of > 250 mg/dl were included in the diabetic groups (dia­betes only, diabetes plus ischemia-reperfusion and diabetes plus dexmedetomidine-ischemia-reperfusion). The rats were kept alive 4 weeks after streptozotocin injection to allow development of chronic dia­betes before they were exposed to ischemia-reperfusion.(19) The rats were weighed before the study. Rats were anesthetized with intraperitoneal ketamine 100 mg/kg. The chest and abdomen were shaved and each animal was fixed in a supine position on the operating table. The abdomen was cleaned with 1% polyvinyl iodine and when dry, the operating field was covered with a sterile drape and median laparotomy was performed. There were four experimental groups (Group C (sham-control; n = 7), (Group DC (diabetes-sham-control; n = 7), Group DIR (diabetes-ischemia-reperfusion; n = 7), and Group DIRD (diabetes-ischemia-reperfusion-dexmedetomidine; n = 7). Sham operation was performed on the rats in Group C and Group DC. The sham operation consisted of mobilization of the hepatic pedicle only. The rats in this group were sacrificed 90 min after the procedure. Hepatic I/R injury was induced in Groups DIR and DIRD respectively with hepatic pedicle clamping using a vascular clamp as in the previous study of Arslan et al.(17) After an ischemic period of 45 min, the vascular clamp was removed. A reperfusion period was maintained for 45 min. In Group DIRD, dexmedetomidine hydrochloride 100 μg/kg, (Precedex 100 μg/2 ml, Abbott®, Abbott Laboratory, North Chicago, Illinois, USA) was administrated via intraperitoneal route 30 minutes before surgery. All the rats were given ketamine 100 mg/kg intraperitoneally and intracardiac blood samples were obtained. Preserving the tissue integrity by avoiding trauma, liver and renal biopsy samples were obtained. Biochemical Analysis: The liver and renal tissues were first washed with cold deionized water to discard blood contamination and then homogenized in a homogenizer. Measurements on cell contest require an initial preparation of the tissues. The preparation procedure may involve grinding of the tissue in a ground glass tissue blender using a rotor driven by a simple electric motor. The homogenizer as a tissue blender similar to the typical kitchen blender is used to emulsify and pulverize the tissue (Heidolph Instruments GMBH & CO KGDiax 900 Germany®) at 1000 U for about 3 min. After centrifugation at 10,000 g for about 60 min, the upper clear layer was taken. MDA levels were determined using the method of Van Ye et al,(20) based on the reaction of MDA with thiobarbituric acid (TBA). In the TBA test reaction, MDA and TBA react in acid pH to form a pink pigment with an absorption maximum at 532 nm. Arbitrary values obtained were compared with a series of standard solutions (1,1,3,3-tetraethoxypropane). Results were expressed as nmol/mg.protein. Part of the homogenate was extracted in ethanol/chloroform mixture (5/3 v/v) to discard the lipid fraction, which caused interferences in the activity measurements of T-SOD, CAT and GST activities. After centrifugation at 10.000 x g for 60 min, the upper clear layer was removed and used for the T-SOD, CAT, GST enzyme activity measurement by methods as described by Durak et al21, Aebi22 and Habig et al23 respectively. One unit of SOD activity was defined as the enzyme protein amount causing 50% inhibition in NBTH2 reduction rate and result were expressed in U/mg protein. The CAT activity method is based on the measurement of absorbance decrease due to H2O2 consumption at 240 nm. The GST activity method is based on the measurement of absorbance changes at 340 nm due to formation of GSH-CDNB complex. Histological determinations: Semiquantitative evaluation technique used by Abdel-Wahhab et al(24) was applied for interpreting the structural changes investigated in hepatic tissues of control and research groups. According to this, (-) (negative point) represents no structural change, while (+) (one positive point) represents mild, (++) (two positive points) medium and (+++) (three positive points) represents severe structural changes. Statistical analysis: The Statistical Package for the Social Sciences (SPSS, Chicago, IL, USA) 20.0 softwre was used for the statistical analysis. Variations in oxidative state parameters, and histopathological examination between study groups were assessed using the Kruskal-Wallis test. The Bonferroni-adjusted Mann-Whitney U-test was used after significant Kruskal-Wallis to determine which groups differed from the others. Results were expressed as mean ± standard deviation (Mean ± SD). Statistical significance was set at a p value < 0.05 for all analyses. RESULTS There was statistically significant difference observed between the groups with respect to findings from the histological changes in the rat liver tissue (hepatocyte degeneration, sinüsoidal dilatation, pycnotic nucleus, prenecrotic cell) determined by light microscopy according to semiquantitative evaluation techniques (p < 0.0001). In Group DIR, hepatocyte degeneration was significantly high compared to Group C, Group DC and Group DIRD (p < 0.0001, p < 0.0001, p = 0.002, respectively), (Table 1, Figure 1-4). Similarly, sinüsoidal dilatation was significantly higher in Group DIR (p < 0.0001, p = 0.004, p = 0.015, respectively). Although, pcynotic nucleus was decreased in Group DIRD, it did not make a significant difference in comparison to Group DIR (p = 0.053), (Table 1, Figure 1-4). The prenecrotic cells were significantly increased in Group DIR, with respect to Group C, Group DC and Group DIRD (p < 0.0001, p = 0.004, p < 0.0001, respectively), (Table 1, Figure 1-4). Table 1. The comparison of histological changes in rat hepatic tissue [Mean ± SD)] p**: Statistical significance was set at a p value < 0.05 for Kruskal-Wallis test *p < 0.05: When compared with Group DIR Figure 1: Light microscopic view of hepatic tissue of Group C (control). VC: vena centralis, *: sinusoids. ®: hepatocytes, k: Kupffer cells, G: glycogen granules, mc: minimal cellular changes, Hematoxilen & Eosin x 40 Figure 2: Light-microscopic view of hepatic tissue of Group DC (diabetes mellitus control) (G: Glycogen granules increased in number, (VC: vena centralis, *:sinusoids. ®:hepatocytes, k:Kupffer cells, G: glycogen granules, mc: minimal cellular changes; Hematoxylin & Eosin x 40) Figure 3: Light-microscopic view of hepatic tissue of Group DIR (Diabetes Mellitus and ischemia-reperfusion) (VC: vena centralis, (H) degenerative and hydrophic hepatocytes, (dej) vena centralis degeneration (centrolobar injury) (*): sinusoid dilatation. (←) pycnotic and hyperchromatic nuclei, MNL: mononuclear cell infiltration, (¯) congestion, K: Kupffer cell hyperplasia, (­) vacuolar degeneration (Hematoxylin & Eosin x 40) Figure 4: Light-microscopic view of hepatic tissue of Group DIRD (Diabetes Mellitus and ischemia-reperfusion together with dexmedetomidine applied group) (VC: vena centralis, (MNL) mononuclear cell infiltration, (dej) hydrophilic degeneration in hepatocytes around vena centralis, (conj) congestion, G: glycogen granules, (←) pycnotic and hyperchromatic nuclei, sinusoid dilatation (*) (Hematoxylin & Eosin x 40) Besides, in liver tissue parenchyma, MN cellular infiltration was a light microscopic finding; and showed significant changes among the groups (p < 0.0001). This was significantly higher in Group DIR, compared to Group C, DC, and DIRD (p < 0.0001, p=0.007, p = 0.007, respectively), (Table 1, Figure 1-4). The enzymatic activity of MDA, SOD and GST in hepatic tissues showed significant differences among the groups [(p = 0.019), (p = 0.034). (p = 0.008) respectively]. MDA enzyme activity was significantly incresed in Group DIR, according to Group C and Group DIRD (p = 0.011, p = 0.016, respectively), (Table 2). In Group DIR SOD enzyme activity was lower with respect to Group C and Group DIRD (p = 0.010, p = 0.038, respectively), (Table 2). The GST enzyme activity was significantly higher in Group DIR, when compared to Group C, DC and DIRD (p = 0.007, p = 0.038, p = 0.039, respectively), (Table 2). Table 2. Oxidative state parameters in rat hepatic tissue [Mean ± SD] p**: Statistical significance was set at a p value < 0.05 for Kruskal-Wallis test *p < 0.05: When compared with Group DIR The enzymatic activity of MDA, SOD in renal tissues, showed significant differences among the groups [(p < 0.0001), (p = 0.008) respectively ]. MDA enzyme activity was significantly incresed in Group DIR, according to Group C and Group DIRD (p < 0.0001, p < 0.0001, respectively). Also MDA enzyme activity level was significantly increased in Group DC, in comparison to Group C and Group DIRD (p = 0.003, p = 0.001, respectively), (Table 3). In Group DIR SOD enzyme activity was lower with respect to Group C and Group DIRD (p = 0.032, p = 0.013, respectively), (Table 3). The GST enzyme activity was significantly higher in Group DIR than the other three groups, however; CAT levels were similar among the groups (Table 3). Table 3: Oxidative state parameters in rat nephrotic tissue [Mean ± SD)] p**: Statistical significance was set at a p value < 0.05 for Kruskal-Wallis test *p < 0.05: When compared with Group DIR DISCUSSION In this study, we have reported the protective effect of dexmedetomidine in experimental hepatic and renal IRI model in the rat by investigating the MDA and SOD levels biochemically. Besides, hepatic histopathological findings also supported our report. Ischemic damage may occur with trauma, hemorrhagic shock, and some surgical interventions, mainly hepatic and renal resections. Reperfusion following ischemia results in even more injury than ischemia itself. IRI is an inflammatory response accompanied by free radical formation, leucocyte migration and activation, sinusoidal endothelial cellular damage, deteoriated microcirculation and coagulation and complement system activation.1 We also detected injury in hepatic and renal tissue caused by reperfusion following ischemia in liver. Experimental and clinical evidence indicates that OS is involved in both the pathogenesis and the complications of diabetes mellitus.25,26 Diabetes mellitus is a serious risk factor for the development of renal and cardiovascular disease. It is also related to fatty changes in the liver.27 Diabetes-related organ damage seems to be the result of multiple mechanisms. Diabetes has been associated with increased free radical reactions and oxidant tissue damage in STZ-induced diabetic rats and also in patients.26Oxidative stress has been implicated in the destruction of pancreatic β-cells28 and could largely contribute to the oxidant tissue damage associated with chronic hyperglycemia.29 A number of reports have shown that antioxidants can attenuate the complications of diabetes in patients30 and in experimental models.28,31 This study demonstrated that diabetes causes a tendency to increase the IRI. There is a lot of investigations related to the pharmacological agents or food supplements applied for decreasing OS and IRI. Antioxidant agents paly an important role in IRI by effecting antioxidant system or lessening the formation of ROS. It has been reported that anesthetic agents too, are effective in oxidative stress.1 During surgical interventions, it seems rational to get benefit from anesthetic agents in prevention of OS caused by IRI instead of using other agents. It has been declared that; dexmedetomidine; as an α-2 agonist with sedative, hypnotic properties; is important in prevention of renal, focal, cerebral, cardiac, testicular and tourniquet-induced IRI.13-18 On the other hand Bostankolu et al. concluded that dexmedetomidine did not have an additional protective role for tournique induced IRI during routine general anesthesia.32 In this study; we have shown that dexmedetomidine has a reducing effect in IRI in diabetic rats. Some biochemical tests and histopathological evaluations are applied for bringing up oxidative stress and IRI in the tissues. Reactive oxygen species (ROS) that appear with reperfusion injury damage cellular structures through the process of the lipid peroxidation of cellular membranes and yield toxic metabolites such as MDA.33 As an important intermidiate product in lipid peroxidation, MDA is used as a sensitive marker of IRI.34 ROS-induced tissue injury is triggered by various defense mechanisms.35 The first defence mechanisms include the antioxidant enzymes of SOD, CAT, and GPx. These endogenous antioxidants are the first lines of defence against oxidative stres and act by scavenging potentially damaging free radical moieties.36 There is a balance between ROS and the scavenging capacity of antioxidant enzymes.1-8 In this study, for evaluation of oxidative damage and antioxidant activity, MDS, SOD, GST and CAT levels were determined in liver and kidney tissues. MDA levels in hepatic and renal tissues were higher in Group DIR compared to Group C and Group DIRD. GST levels were higher in Group DIR compared to all the other three groups. When the groups were arranged from highest to lowest order, with respect to CAT levels, the order was; Group DIR, Group DIRD, Group DC and Group C. However, the difference was not significant. The acute phase reactant MDA, as a marker of OS, was found to be high in Group DIR and low in Group DIRD. This could be interpreted as the presence of protective effect of dexmedetomidine in IRI. IRI developing in splanchnic area causes injury also in the other organs.35 Leithead et al showed that clinically significant hepatic IRI demonstrates a strong relationship with peri-operative acute kidney injury.2 In our experimental research that showed correlation to that of research by Leithead et al. After hepatic IRI in diabetic rats renal OS marker MDA levels were significantly more in Group DIR than Group DIRD. In our study, we observed histopathological changes in the ischemic liver tissue and alterations in the level of MDA, SOD, GST and CAT levels which are OS markers. Histopathological changes of the liver tissues are hepatocyt degeneration, sinusoidal dilatation, nuclear picnosis, celluler necrosis, mononuclear cell infiltrationat paranchimal tissue. These histopathological injury scores were significantly lower in the Group DIRD than those in group DIR. LIMITATION Study limitation is there was no negative control group, as this type of surgical intervention is not possible in rats without anesthesia. CONCLUSION The enzymatic findings of our study together with the hepatic histopathology indicate that dexmedetomidine has a potential role to decrease ischemia-reperfusion injury. Conflict of interest and funding: The authors have not received any funding or benefits from industry or elsewhere to conduct this study. 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