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Статті в журналах з теми "Loop domain model"
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Aguirre, L. A. "Open-loop model matching in frequency domain." Electronics Letters 28, no. 5 (1992): 484. http://dx.doi.org/10.1049/el:19920305.
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Su, Y., and G. J. Weng. "A polycrystal hysteresis model for ferroelectric ceramics." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 462, no. 2069 (February 14, 2006): 1573–92. http://dx.doi.org/10.1098/rspa.2005.1616.
Повний текст джерелаАнотація:
Most key elements of ferroelectric properties are defined through the hysteresis loops. For a ferroelectric ceramic, its loop is contributed collectively by its constituent grains, each having its own hysteresis loop when the ceramic polycrystal is under a cyclic electric field. In this paper, we propose a polycrystal hysteresis model so that the hysteresis loop of a ceramic can be calculated from the loops of its constituent grains. In this model a micromechanics-based thermodynamic approach is developed to determine the hysteresis behaviour of the constituent grains, and a self-consistent scheme is introduced to translate these behaviours to the polycrystal level. This theory differs from the classical phenomenological ones in that it is a micromechanics-based thermodynamic approach and it can provide the evolution of new domain concentration among the constituent grains. It also differs from some recent micromechanics studies in its secant form of self-consistent formulation and in its application of irreversible thermodynamics to derive the kinetic equation of domain growth. To put this two-level micromechanics theory in perspective, it is applied to a ceramic PLZT 8/65/35, to calculate its hysteresis loop between the electric displacement and the electric field ( D versus E ), and the butterfly-shaped longitudinal strain versus the electric field relation ( ϵ versus E ). The calculated results are found to be in good quantitative agreement with the test data. The corresponding evolution of new domain concentration c 1 and the individual hysteresis loops of several selected grains—along with those of the overall polycrystal—are also illustrated.
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Chakrapani, Sudha, Timothy D. Bailey, and Anthony Auerbach. "Gating Dynamics of the Acetylcholine Receptor Extracellular Domain." Journal of General Physiology 123, no. 4 (March 29, 2004): 341–56. http://dx.doi.org/10.1085/jgp.200309004.
Повний текст джерелаАнотація:
We used single-channel recording and model-based kinetic analyses to quantify the effects of mutations in the extracellular domain (ECD) of the α-subunit of mouse muscle–type acetylcholine receptors (AChRs). The crystal structure of an acetylcholine binding protein (AChBP) suggests that the ECD is comprised of a β-sandwich core that is surrounded by loops. Here we focus on loops 2 and 7, which lie at the interface of the AChR extracellular and transmembrane domains. Side chain substitutions in these loops primarily affect channel gating by either decreasing or increasing the gating equilibrium constant. Many of the mutations to the β-core prevent the expression of functional AChRs, but of the mutants that did express almost all had wild-type behavior. Rate-equilibrium free energy relationship analyses reveal the presence of two contiguous, distinct synchronously-gating domains in the α-subunit ECD that move sequentially during the AChR gating reaction. The transmitter-binding site/loop 5 domain moves first (Φ = 0.93) and is followed by the loop 2/loop 7 domain (Φ = 0.80). These movements precede that of the extracellular linker (Φ = 0.69). We hypothesize that AChR gating occurs as the stepwise movements of such domains that link the low-to-high affinity conformational change in the TBS with the low-to-high conductance conformational change in the pore.
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Aguirre, L. A. "Erratum: Open-loop model matching in frequency domain." Electronics Letters 28, no. 8 (1992): 808. http://dx.doi.org/10.1049/el:19920509.
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Szewczyk, Roman. "Model of the Magnetostrictive Hysteresis Loop with Local Maximum." Materials 12, no. 1 (December 30, 2018): 105. http://dx.doi.org/10.3390/ma12010105.
Повний текст джерелаАнотація:
This paper presents a model of the magnetostrictive hysteresis loop with local maximum. The model is based on the differential equations describing magnetostriction due to the domain wall movement as well as domain magnetization rotation. The transition between these mechanisms of magnetization is quantified by the Maxwell–Boltzmann distribution. Moreover, the lift-off phenomenon in the magnetostrictive hysteresis loop is considered. The proposed model was validated on the results of measurements of magnetostrictive hysteresis loops of Mn0.70Zn0.24Fe2.06O4 ferrite for power application and 13CrMo4-5 construction steel. The results of modeling confirm that the proposed model corresponds well with experimental results. Good agreement was confirmed by determination coefficient R2, which exceeded 0.995 and 0.985 for Mn0.70Zn0.24Fe2.06O4 ferrite for power application and 13CrMo4-5 construction steel, respectively.
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Camia, Federico, Alberto Gandolfi, Giovanni Peccati, and Tulasi Ram Reddy. "Brownian Loops, Layering Fields and Imaginary Gaussian Multiplicative Chaos." Communications in Mathematical Physics 381, no. 3 (February 2021): 889–945. http://dx.doi.org/10.1007/s00220-020-03932-9.
Повний текст джерелаАнотація:
AbstractWe study fields reminiscent of vertex operators built from the Brownian loop soup in the limit as the loop soup intensity tends to infinity. More precisely, following Camia et al. (Nucl Phys B 902:483–507, 2016), we take a (massless or massive) Brownian loop soup in a planar domain and assign a random sign to each loop. We then consider random fields defined by taking, at every point of the domain, the exponential of a purely imaginary constant times the sum of the signs associated to the loops that wind around that point. For domains conformally equivalent to a disk, the sum diverges logarithmically due to the small loops, but we show that a suitable renormalization procedure allows to define the fields in an appropriate Sobolev space. Subsequently, we let the intensity of the loop soup tend to infinity and prove that these vertex-like fields tend to a conformally covariant random field which can be expressed as an explicit functional of the imaginary Gaussian multiplicative chaos with covariance kernel given by the Brownian loop measure. Besides using properties of the Brownian loop soup and the Brownian loop measure, a main tool in our analysis is an explicit Wiener–Itô chaos expansion of linear functionals of vertex-like fields. Our methods apply to other variants of the model in which, for example, Brownian loops are replaced by disks.
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Du, Wenhao, Haixia Zhu, Jiaqiang Qian, Dongmei Xue, Sen Zheng, and Qiang Huang. "Full-Length Model of SaCas9-sgRNA-DNA Complex in Cleavage State." International Journal of Molecular Sciences 24, no. 2 (January 7, 2023): 1204. http://dx.doi.org/10.3390/ijms24021204.
Повний текст джерелаАнотація:
Staphylococcus aureus Cas9 (SaCas9) is a widely used genome editing tool. Understanding its molecular mechanisms of DNA cleavage could effectively guide the engineering optimization of this system. Here, we determined the first cryo-electron microscopy structure of the SaCas9-sgRNA-DNA ternary complex. This structure reveals that the HNH nuclease domain is tightly bound to the cleavage site of the target DNA strand, and is in close contact with the WED and REC domains. Moreover, it captures the complete structure of the sgRNA, including the previously unresolved stem-loop 2. Based on this structure, we build a full-length model for the ternary complex in cleavage state. This model enables identification of the residues for the interactions between the HNH domain and the WED and REC domains. Moreover, we found that the stem-loop 2 of the sgRNA tightly binds to the PI and RuvC domains and may also regulate the position shift of the RuvC domain. Further mutagenesis and molecular dynamics simulations supported the idea that the interactions of the HNH domain with the WED and REC domains play an important role in the DNA cleavage. Thus, this study provides new mechanistic insights into the DNA cleavage of SaCas9 and is also useful for guiding the future engineering of SaCas9-mediated gene editing systems.
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Kumar, Sandip, David G. Priest, Yan Yan, Ian B. Dodd, Keith E. Shearwin, and David D. Dunlap. "Estimation of DNA Loop Interactions Supports the Loop Domain Model of Insulator Action." Biophysical Journal 108, no. 2 (January 2015): 164a. http://dx.doi.org/10.1016/j.bpj.2014.11.904.
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Sain, Chiranjit, Atanu Banerjee, and Pabitra Kumar Biswas. "Comparative Performance Study for Closed Loop Operation of an Adjustable Speed Permanent Magnet Synchronous Motor Drive with Different Controllers." International Journal of Power Electronics and Drive Systems (IJPEDS) 7, no. 4 (December 1, 2016): 1085. http://dx.doi.org/10.11591/ijpeds.v7.i4.pp1085-1099.
Повний текст джерелаАнотація:
In this paper an extensive comparative study is carried out between PI and PID controlled closed loop model of an adjustable speed Permanent Magnet Synchronous Motor (PMSM) drive. The incorporation of Sinusoidal Pulse Width Modulation (SPWM) strategy establishes near sinusoidal armature phase currents and comparatively less torque ripples without sacrificing torque/weight ratio. In this closed loop model of PMSM drive, the information about reference speed is provided to a speed controller, to ensure that actual drive speed tracks the reference speed with ideally zero steady state speed error. The entire model of PMSM closed loop drive is divided into two loops, inner loop current and outer loop speed. By taking the different combinations of two classical controllers (PI & PID) related with two loop control structure, different approximations are carried out. Hence a typical comparative study is introduced to familiar with the different performance indices of the system corresponding to time domain and frequency domain specifications. Therefore overall performance of closed loop PMSM drive is tested and effectiveness of controllers will be determined for different combinations.
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Jiang, Jian Hu, Chao Wu, and Ting Bu. "Open-Loop Frequency Domain Analysis Based on System Identification." Advanced Materials Research 452-453 (January 2012): 364–68. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.364.
Повний текст джерелаАнотація:
In this paper, an open-loop frequency domain analysis based on system identification is introduced. Using model identification tools in Matlab, the open-loop frequency domain characteristic could be derived accurately with the open-loop step response. Then, the closed-loop regulator could be designed with the open-loop frequency domain characteristic to fulfill the steady and dynamic requirements. This method is suitable for most of the systems. An example of Buck converter is proposed to represent the analysis process. Simulation model is built in Matlab software, and some factors which affect the precision of model identification and frequency domain analysis are taken into consideration. Finally, both open- and closed-loop experimental results verify the feasibility of the proposed scheme.
Дисертації з теми "Loop domain model"
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Parveen, Tania. "Composite load model decomposition : induction motor contribution." Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/31301/1/Tania_Parveen_Thesis.pdf.
Повний текст джерелаАнотація:
In this thesis, a new technique has been developed for determining the composition of a collection of loads including induction motors. The application would be to provide a representation of the dynamic electrical load of Brisbane so that the ability of the power system to survive a given fault can be predicted. Most of the work on load modelling to date has been on post disturbance analysis, not on continuous on-line models for loads. The post disturbance methods are unsuitable for load modelling where the aim is to determine the control action or a safety margin for a specific disturbance. This thesis is based on on-line load models. Dr. Tania Parveen considers 10 induction motors with different power ratings, inertia and torque damping constants to validate the approach, and their composite models are developed with different percentage contributions for each motor. This thesis also shows how measurements of a composite load respond to normal power system variations and this information can be used to continuously decompose the load continuously and to characterize regarding the load into different sizes and amounts of motor loads.
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Koussaifi, Maroun. "Modélisation centrée utilisateur pour la configuration logicielle en environnement ambiant." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30212.
Повний текст джерелаАнотація:
L'intelligence ambiante vise à offrir à un utilisateur humain des applications et des services personnalisés et adaptés à la situation courante. L'environnement ambiant, dans lequel cet humain est plongé, est composé d'un ensemble d'objets connectés et de composants logiciels qui sont des briques de base pour la construction d'applications par composition. La disponibilité de ces composants peut varier dynamiquement, en cas de mobilité par exemple. Ceux-ci peuvent apparaître ou disparaître de manière non anticipée. De plus, dans ces environnements dynamiques et ouverts, le besoin de l'utilisateur humain n'est pas stable ni toujours bien défini. Pour construire des applications dans un tel contexte, et fournir à l'utilisateur "les bonnes applications au bon moment", notre équipe explore une approche originale appelée "composition logicielle opportuniste" : l'idée est de construire des applications à la volée par assemblage de composants logiciels présents dans l'environnement sur le moment, sans se baser sur des besoins explicites ni sur des schémas de construction prédéfinis. C'est l'opportunité qui déclenche la construction des applications à la volée. Elle est contrôlée par un système intelligent, appelé moteur de composition opportuniste, qui doit décider des "bonnes" compositions à effectuer sans contribution explicite de l'utilisateur. Ainsi, les applications "émergent" dynamiquement. Les applications émergentes peuvent être imprévues ou inconnues de l'utilisateur. Au centre du système, ce dernier doit être en informé. Il doit pouvoir les contrôler, c'est-à-dire les accepter ou les rejeter, et s'il a les compétences requises, les modifier ou même construire lui-même des applications en assemblant des composants logiciels présents dans l'environnement ambiant. Dans les tâches de contrôle, l'utilisateur doit être assisté au mieux. D'autre part, pour que le moteur de composition opportuniste construise des assemblages pertinents en l'absence de besoins explicites, il doit recevoir des informations de l'utilisateur. Ceci ne doit cependant pas entraîner, pour l'utilisateur, une surcharge d'information ou d'opérations à effectuer. Dans cette thèse, nous proposons une approche basée sur l'ingénierie dirigée par les modèles (IDM) afin de mettre l'utilisateur "au centre de la boucle". Il s'agit de lui présenter les applications émergentes, de l'assister dans son contrôle et d'extraire des données de feedback utiles à fournir au moteur de composition "intelligent". Notre solution repose sur un métamodèle d'assemblage de composants logiciels, des langages spécifiques à un domaine (DSL) qui supportent la description des applications, un éditeur graphique qui permet d'éditer les applications et de capturer le feedback de l'utilisateur. Différentes transformations de modèle permettent l'interfaçage avec le moteur de composition et la génération de différentes formes de descriptions structurelles et sémantiques des applications pour des utilisateurs différents. En outre, les descriptions peuvent être facilement ajustées à un humain particulier, en changeant ou en adaptant les DSL et les transformations de modèle au profil de l'utilisateur. Dans notre approche, contrairement à l'utilisation classique de l'IDM où les outils et les techniques sont utilisés par les ingénieurs pour développer des logiciels et générer du code, le focus est sur les utilisateurs finaux qui prennent la place des ingénieurs. L'ensemble de la solution a été implémentée et fonctionne de manière couplée avec le moteur de composition opportuniste : notre solution prend en entrée les applications proposées par le moteur, les transforme en des modèles présentables, compréhensibles et modifiables par l'utilisateur, et enfin capture le feedback de l'utilisateur pour le transmettre au moteur pour mettre à jour sa connaissanceAmbient intelligence aims to provide to human users applications and services that are personalized and adapted to the current situation. The ambient environment which surrounds the human consists of a set of connected objects and software components that are bricks used for the construction of applications by composition. The availability of these components can vary dynamically, in case of mobility for example. In addition, their appearance or disappearance is usually unanticipated. Moreover, in these dynamic and open environments, the user needs are not stable nor always well defined. To build these applications and provide the user with "the right applications at the right time", our team explores an original approach called "opportunistic software composition": the idea is to build applications on the fly by assembling software components present in the environment at the time, without relying on explicit user needs or predefined applications models. Here, it is the availability of the components that triggers opportunistically the on-the-fly building of applications. It is controlled by an intelligent system, called opportunistic composition engine, which decides on the "right" compositions to be made without user input. In such a way, the applications "emerge" dynamically from the ambient environment. Thus, emerging applications can be unexpected or unknown to the user. At the center of the system, the latter must be informed of these applications. On the first hand, she/he must be able to control them, i.e., accept or reject them, and if she/he has the required skills, modify them or eventually build applications herself/himself by assembling software components present in the ambient environment. However, in the control tasks, the user must be assisted as well as possible. On the other hand, in order for the opportunistic composition engine to build relevant assemblies in the absence of explicit needs, it must receive information from the user. In this thesis, we propose an approach based on Model Driven Engineering (MDE) in order to put the user "at the center of the loop". The objective is to present the emerging applications to the user, to assist him in his interventions and to extract useful feedback data to provide to the "intelligent" composition engine. Our solution is based on a metamodel for assembling software components, on different domain-specific languages (DSL) that support application descriptions, and on a graphical editor for editing applications and capturing user feedback. Different methods for model transformations are used to generate structural and semantic application descriptions for different users, from the applications models build by the intelligent engine. In addition, the descriptions can be easily adjusted to a particular human, by changing or adapting the DSL and the model transformations to the user's profile. Unlike the traditional use of MDE where tools and techniques are used by engineers to develop software and generate code, the focus in our approach is on the end users. The entire solution has been implemented and works coupled with the engine. That is to say, our solution is able to intercept the applications models built by the engine, to transform them into presentable models that can be understood and modified by the user, and finally to capture the user feedback and give it back to the engine to update its knowledge
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Prastowo, Tadeus. "Toward C++ as a Platform for Language-Oriented Programming: On the Embedding of a Model-Based Real-Time Language." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/256168.
Повний текст джерелаАнотація:
Cyber-physical systems are dynamic physical systems that are controlled by computers for their safe and sound operations (e.g., cars, satellites, robots, elevators, and many others). Consequently, the programs running cyber-physical systems have real-time requirements, which require the programs to compute not only correctly but also timely because dynamic physical systems need to move to correct positions within certain duration to ensure safe and sound operations. To satisfy real-time requirements in better ways, many real-time languages have been proposed in the literature. Nevertheless, the general-purpose non-real-time languages C and C++ have remained the de facto languages to program cyber-physical systems, including Mars rovers and F-35 jet fighters. Given this reality, the better ways to satisfy real-time requirements have been the use of model-based tools (e.g., MATLAB/Simulink) that allow cyber-physical systems to be designed by modeling and simulating them and the resulting models to be translated automatically to C programs. Model-based tools, however, leave the resulting C programs for manual integration with other C/C++ programs, such as legacy/third-party device drivers and libraries. Since manual integration could slip in some inconsistencies, which proved fatal in the maiden flight of Ariane-5 rocket, this work shows how the standard features of C++, which support active libraries, can be used to embed a model-based real-time language, called Tice, as a C++ active library that can be used to declaratively express models of real-time systems that are processable by off-the-shelf standard C++ compilers (e.g., GCC and Clang) that automatically not only translate the models into C/C++ programs but also check both the validity of the models and the consistency of the models with other C/C++ programs. Furthermore, being compilable by off-the-shelf standard C++ compilers also sets Tice apart from other real-time languages already proposed in the literature because the other languages require either their own special compilers/interpreters or non-standard C/C++ compilers. Consequently, while Tice itself either uses no C++ features that are unsuitable for cyber-physical systems (e.g., exception) or uses some in judicious manner (e.g., template instantiations to generate programs), Tice prevents no usage that is permitted by standard C++ compilers. Beside that, as C++ active libraries are indeed ordinary C++ libraries, C++ active libraries are seamlessly composable as ordinary C++ libraries, and therefore, as models play an increasingly important role in software engineering, this work shows the potential of C++ as a platform for language-oriented programming where different languages that express different kinds of models and are embedded as C++ active libraries could be composed seamlessly.
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Woodbury, Nathan Scott. "Representation and Reconstruction of Linear, Time-Invariant Networks." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7402.
Повний текст джерелаАнотація:
Network reconstruction is the process of recovering a unique structured representation of some dynamic system using input-output data and some additional knowledge about the structure of the system. Many network reconstruction algorithms have been proposed in recent years, most dealing with the reconstruction of strictly proper networks (i.e., networks that require delays in all dynamics between measured variables). However, no reconstruction technique presently exists capable of recovering both the structure and dynamics of networks where links are proper (delays in dynamics are not required) and not necessarily strictly proper.The ultimate objective of this dissertation is to develop algorithms capable of reconstructing proper networks, and this objective will be addressed in three parts. The first part lays the foundation for the theory of mathematical representations of proper networks, including an exposition on when such networks are well-posed (i.e., physically realizable). The second part studies the notions of abstractions of a network, which are other networks that preserve certain properties of the original network but contain less structural information. As such, abstractions require less a priori information to reconstruct from data than the original network, which allows previously-unsolvable problems to become solvable. The third part addresses our original objective and presents reconstruction algorithms to recover proper networks in both the time domain and in the frequency domain.
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Priest, David Geoffrey. "Testing the DNA loop domain model in Escherichia coli." Thesis, 2014. http://hdl.handle.net/2440/99568.
Повний текст джерелаАнотація:
The ability of DNA to form loops has been employed by evolution in almost every aspect of biology involving DNA, not least the regulation of gene transcription. The biophysical constraints on looping of the DNA polymer at short range (< 300 bp) have been extensively studied, however it is uncertain how the probability of DNA looping decays at longer range. The first part of this thesis presents a quantitative investigation of long range DNA looping both in vivo in E. coli and in vitro. DNA looping is more efficient in vivo than measured in vitro (by our collaborators) with the technique of Tethered Particle Motion (TPM), and we suggest that DNA supercoiling aids DNA looping in vivo. By measuring long-range looping in vivo using the two well-characterised looping proteins (the LacI and λCI repressors) and thermodynamic models of DNA looping, the decay in looping probability is quantified over the range 242–10000 bp. Furthermore this decay is shown to be a property of the DNA tether linking the loop, independent of the nature of the DNA looping protein(s). Enhancers activate genes at long distance irrespective of position and orientation, so why don’t enhancers activate the wrong genes? In other words, what mechanisms drive efficiency and specificity in enhancer-promoter looping? The loop domain model proposes that DNA loops formed by insulators pose a topological barrier that restricts the reach of enhancers to the vicinity of desired target promoter(s). Specifically, the model predicts that two DNA loops in an alternating arrangement should form somewhat mutually exclusively (i.e. they should interfere with one another’s formation), whereas nested DNA loops are predicted to assist one another’s formation, and side-by-side loops should form independently. In the second part of this thesis, the loop domain model is tested in E. coli by combining LacI and λCI-mediated DNA loops in these different orientations. Accordingly, we quantify DNA looping assistance and interference by fitting experimental data to a statistical-mechanical model, confirming the predictions of the loop domain model. Furthermore, TPM measurements of the same looping constructs support predictions that non-supercoiled DNA in vitro should facilitate DNA looping assistance, but not interference. In addition to confirming the loop domain model in E. coli, this thesis provides a strong experimental and theoretical foundation for further investigations of enhancer-promoter looping in prokaryotes and eukaryotes, and the relationship between chromatin architecture and gene expression in metazoans.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Molecular and Biomedical Science, 2014.
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Broccoli, Sonia. "Étude des mécanismes de surenroulement de l'ADN induit par la transcription chez Escherichia coli." Thèse, 2003. http://hdl.handle.net/1866/15055.
Повний текст джерелаКниги з теми "Loop domain model"
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Hudson, Bob. Clients, Consumers or Citizens? Policy Press, 2021. http://dx.doi.org/10.1332/policypress/9781447355694.001.0001.
Повний текст джерелаАнотація:
Adult social care was the first major social policy domain in England to be transferred from the state to the market. There is now a forty-year period to look back at to consider the thinking behind the strategy, the impacts on commissioners and providers of care, on the care workforce and on those who use care and support services. In this book, Bob Hudson meticulously charts these shifts. He examines the shift from philanthropic endeavour to state planning and provision, through to the marketisation of services and support. He challenges the dominant market paradigm, explores alternative models for a post-Covid future and locates the debate within the wider literature on political thinking and policy change.
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Sparti, Davide. On the Edge. Edited by George E. Lewis and Benjamin Piekut. Oxford University Press, 2014. http://dx.doi.org/10.1093/oxfordhb/9780195370935.013.020.
Повний текст джерелаАнотація:
While all human agency unfolds with a certain degree of improvisation, there are specific cultural practices in which improvisation plays an even more relevant role. Among these, jazz offers a privileged site for understanding how improvisation operates, offering the opportunity to find within it a frame of reference that might be related to other genres and modes of creation. This contribution, as Wittgenstein would say, has a “grammatical” design to it. It proposes to clarify the significance of the term “improvisation” by reflecting upon theconditionsthat make the practice possible. Rather than calling forth mysterious processes that take place in the unconscious or in the minds of musicians, the focus is on the criteria that must be satisfied before one may accurately ascribe to an act the concept of improvisation. By comparing the practice of improvisation to the notion a musical “work,” five such criteria are established: inseparability, irreversibility, situationality, originality, and responsiveness. The last part of this chapter offers an insight into the improvising dynamic. Unlike a composer in the domain of classical music, who works from a plan looking ahead, improvising musicians cannot by definition look ahead. Yet they can look behind at what has already been played, and respond to it, extending the logic of the previous phrases, shaping a form retrospectively, blending the emergent with the intended. Hence any musical statement emerging during a performance is at the same time a constraint and a springboard for the following statement.
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Harnish, Stacy M. Anomia and Anomic Aphasia: Implications for Lexical Processing. Edited by Anastasia M. Raymer and Leslie J. Gonzalez Rothi. Oxford University Press, 2015. http://dx.doi.org/10.1093/oxfordhb/9780199772391.013.7.
Повний текст джерелаАнотація:
Anomia is a term that describes the inability to retrieve a desired word, and is the most common deficit present across different aphasia syndromes. Anomic aphasia is a specific aphasia syndrome characterized by a primary deficit of word retrieval with relatively spared performance in other language domains, such as auditory comprehension and sentence production. Damage to a number of cognitive and motor systems can produce errors in word retrieval tasks, only subsets of which are language deficits. In the cognitive and neuropsychological underpinnings section, we discuss the major processing steps that occur in lexical retrieval and outline how deficits at each of the stages may produce anomia. The neuroanatomical correlates section will include a review of lesion and neuroimaging studies of language processing to examine anomia and anomia recovery in the acute and chronic stages. The assessment section will highlight how discrepancies in performance between tasks contrasting output modes and input modalities may provide insight into the locus of impairment in anomia. Finally, the treatment section will outline some of the rehabilitation techniques for forms of anomia, and take a closer look at the evidence base for different aspects of treatment.
Частини книг з теми "Loop domain model"
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Beyer, Dirk, Marian Lingsch Rosenfeld, and Martin Spiessl. "A Unifying Approach for Control-Flow-Based Loop Abstraction." In Software Engineering and Formal Methods, 3–19. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-17108-6_1.
Повний текст джерелаАнотація:
AbstractLoop abstraction is a central technique for program analysis, because loops can cause large state-space representations if they are unfolded. In many cases, simple tricks can accelerate the program analysis significantly. There are several successful techniques for loop abstraction, but they are hard-wired into different tools and therefore difficult to compare and experiment with. We present a framework that allows us to implement different loop abstractions in one common environment, where each technique can be freely switched on and off on-the-fly during the analysis. We treat loops as part of the abstract model of the program, and use counterexample-guided abstraction refinement to increase the precision of the analysis by dynamically activating particular techniques for loop abstraction. The framework is independent from the underlying abstract domain of the program analysis, and can therefore be used for several different program analyses. Furthermore, our framework offers a sound transformation of the input program to a modified, more abstract output program, which is unsafe if the input program is unsafe. This allows loop abstraction to be used by other verifiers and our improvements are not ‘locked in’ to our verifier. We implemented several existing approaches and evaluate their effects on the program analysis.
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Vilalta, Ricardo, and Mikhail M. Meskhi. "Transfer of Knowledge Across Tasks." In Metalearning, 219–36. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-67024-5_12.
Повний текст джерелаАнотація:
AbstractThis area is often referred to as transfer of knowledge across tasks, or simply transfer learning; it aims at developing learning algorithms that leverage the results of previous learning tasks. This chapter discusses different approaches in transfer learning, such as representational transfer, where transfer takes place after one or more source models have been trained. There is an explicit form of knowledge transferred directly to the target model or to the meta-model. The chapter also discusses functional transfer, where two or more models are trained simultaneously. This situation is sometimes referred to as multi-task learning. In this approach, the models share their internal structure (or possibly some parts) during learning. Other topics include instance-, feature-, and parameter-based transfer learning, often used to initialize the search on the target domain. A distinct topic is transfer learning in neural networks, which includes, for instance, the transfer of a part of the network structure. The chapter also presents the double loop architecture, where the base-learner iterates over the training set in an inner loop, while the metalearner iterates over different tasks to learn metaparameters in an outer loop. Details are given on transfer learning within kernel methods and parametric Bayesian models.
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Girardi, Dominic, Josef Kueng, and Andreas Holzinger. "A Domain-Expert Centered Process Model for Knowledge Discovery in Medical Research: Putting the Expert-in-the-Loop." In Brain Informatics and Health, 389–98. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-23344-4_38.
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Reinhardt, Oliver, Tom Warnke, and Adelinde M. Uhrmacher. "Agent-Based Modelling and Simulation with Domain-Specific Languages." In Towards Bayesian Model-Based Demography, 113–34. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-83039-7_7.
Повний текст джерелаАнотація:
AbstractConducting simulation studies within a model-based framework is a complex process, in which many different concerns must be considered. Central tasks include the specification of the simulation model, the execution of simulation runs, the conduction of systematic simulation experiments, and the management and documentation of the model’s context. In this chapter, we look into how these concerns can be separated and handled by applying domain-specific languages (DSLs), that is, languages that are tailored to specific tasks in a specific application domain. We demonstrate and discuss the features of the approach by using the modelling language ML3, the experiment specification language SESSL, and PROV, a graph-based standard to describe the provenance information underlying the multi-stage process of model development.
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Siddiqui, Faizan, Thomas Höllt, and Anna Vilanova. "Uncertainty in the DTI Visualization Pipeline." In Mathematics and Visualization, 125–48. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-56215-1_6.
Повний текст джерелаАнотація:
AbstractDiffusion-Weighted Magnetic Resonance Imaging (DWI) enables the in-vivo visualization of fibrous tissues such as white matter in the brain. Diffusion-Tensor Imaging (DTI) specifically models the DWI diffusion measurements as a second order-tensor. The processing pipeline to visualize this data, from image acquisition to the final rendering, is rather complex. It involves a considerable amount of measurements, parameters and model assumptions, all of which generate uncertainties in the final result which typically are not shown to the analyst in the visualization. In recent years, there has been a considerable amount of work on the visualization of uncertainty in DWI, and specifically DTI. In this chapter, we primarily focus on DTI given its simplicity and applicability, however, several aspects presented are valid for DWI as a whole. We explore the various sources of uncertainties involved, approaches for modeling those uncertainties, and, finally, we survey different strategies to visually represent them. We also look at several related methods of uncertainty visualization that have been applied outside DTI and discuss how these techniques can be adopted to the DTI domain. We conclude our discussion with an overview of potential research directions.
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Platz, Roland. "Approach to Assess Basic Deterministic Data and Model Form Uncertaint in Passive and Active Vibration Isolation." In Lecture Notes in Mechanical Engineering, 208–23. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77256-7_17.
Повний текст джерелаАнотація:
AbstractThis contribution continues ongoing own research on uncertainty quantification in structural vibration isolation in early design stage by various deterministic and non-deterministic approaches. It takes into account one simple structural dynamic system example throughout the investigation: a one mass oscillator subject to passive and active vibration isolation. In this context, passive means that the vibration isolation only depends on preset inertia, damping, and stiffness properties. Active means that additional controlled forces enhance vibration isolation. The simple system allows a holistic, consistent and transparent look into mathematical modeling, numerical simulation, experimental test and uncertainty quantification for verification and validation. The oscillator represents fundamental structural dynamic behavior of machines, trusses, suspension legs etc. under variable mechanical loading. This contribution assesses basic experimental data and mathematical model form uncertainty in predicting the passive and enhanced vibration isolation after model calibration as the basis for further deterministic and non-deterministic uncertainty quantification measures. The prediction covers six different damping cases, three for passive and three for active configuration. A least squares minimization (LSM) enables calibrating multiple model parameters using different outcomes in time and in frequency domain from experimental observations. Its adequacy strongly depends on varied damping properties, especially in passive configuration.
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Zander, Justyna, and Ina Schieferdecker. "Model-Based Testing of Embedded Systems Exemplified for the Automotive Domain." In Behavioral Modeling for Embedded Systems and Technologies, 377–413. IGI Global, 2010. http://dx.doi.org/10.4018/978-1-60566-750-8.ch015.
Повний текст джерелаАнотація:
The purpose of this chapter is to introduce the test methods applied for embedded systems addressing selected problems in the automotive domain. Model-based test approaches are reviewed and categorized. Weak points are identified and a novel test method is proposed. It is called model-in-the-loop for embedded system test (MiLEST) and is realized in MATLAB®/Simulink®/Stateflow® environment. Its main contribution refers to functional black-box testing based on the system and test models. It is contrasted with the test methods currently applied in the industry that form dedicated solutions, usually specialized in a concrete testing context. The developed signal-feature-oriented paradigm developed herewith allows the abstract description of signals and their properties. It addresses the problem of missing reference signal flows and allows for a systematic and automatic test data selection. Processing of both discrete and continuous signals is possible, so that the hybrid behavior of embedded systems can be handled.
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Barrouillet, Pierre, and Valérie Camos. "The Time-Based Resource-Sharing Model of Working Memory." In Working Memory, 85–115. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198842286.003.0004.
Повний текст джерелаАнотація:
The time-based resource-sharing model considers working memory as the workspace in which mental representations are built, maintained, and transformed for completing goal-oriented tasks. Its main component is made of an episodic buffer and a procedural system that form an executive loop in which processing and storage share domain-general attentional resources on a temporal basis. Because working memory representations decay with time when attention is diverted, the cognitive load of a given activity is the proportion of time during which it occupies attention and prevents it from counteracting this decay through attentional refreshing. Consequently, recall in working memory tasks is an inverse function of the cognitive load of concurrent processing. Besides this system, an independent domain-specific maintenance system exists for verbal, but not visuospatial, information. Within this framework, working memory development mainly results from increasing processing speed that affects both the duration of the distraction of attention by concurrent tasks and refreshing efficiency.
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"Loop Domains Model." In Encyclopedia of Genetics, Genomics, Proteomics and Informatics, 1122. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6754-9_9571.
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Paláncz, Béla, Levente Kovács, Balázs Benyó, and Zoltán Benyó. "Robust Blood-Glucose Control of Type I Diabetes Patients Under Intensive Care Using Mathematica." In Encyclopedia of Healthcare Information Systems, 1210–19. IGI Global, 2008. http://dx.doi.org/10.4018/978-1-59904-889-5.ch151.
Повний текст джерелаАнотація:
This article presents a robust control design method on frequency domain using Mathematica for regularization of glucose level in Type I diabetes persons under intensive care. The method originally proposed under Mathematica by Helton and Merino (1998) is now improved with a disturbance rejection constraint inequality, and is tested on the three-state minimal model. Nonlinear closed loop simulation in state-space, in case of standard meal disturbances, demonstrates the robustness of the resulted high-order linear controller. The obtained results are compared with H8 design implemented with Matlab, proving that the controller (for the considered model parameters) can operate properly, even in case of parameter values of the worst-case scenario.
Тези доповідей конференцій з теми "Loop domain model"
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Bailey, R. C., and S. Cheesman. "LI model Norm inversion of resistive limit frequency‐domain loop‐loop electromagnetic data." In SEG Technical Program Expanded Abstracts 1992. Society of Exploration Geophysicists, 1992. http://dx.doi.org/10.1190/1.1822107.
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Jalili-Marandi, Vahid, Jean Belanger, and Fabio Jose Ayres. "Model-in-the-Loop real-time simulation in phasor domain." In 2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE). IEEE, 2014. http://dx.doi.org/10.1109/isie.2014.6864973.
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"Phase-frequency Domain Model of Costas Loop with Mixer Discriminator." In 10th International Conference on Informatics in Control, Automation and Robotics. SciTePress - Science and and Technology Publications, 2013. http://dx.doi.org/10.5220/0004479104270433.
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John, Malte, and Axel Mertens. "Frequency-Domain Model of Voltage-Source Inverters with Closed-Loop Current Control." In 2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL). IEEE, 2018. http://dx.doi.org/10.1109/compel.2018.8459995.
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Kirei, Botond Sandor, Calin Farcas, Robert Groza, and Marina Dana Topa. "An all-digital frequency locked loop and its linearized S-domain model." In 2017 International Symposium ELMAR. IEEE, 2017. http://dx.doi.org/10.23919/elmar.2017.8124442.
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Jung, Hunsang, Youngjin Park, and K. C. Park. "Mode Decoupling Controller for Feedback Model Updating." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59697.
Повний текст джерелаАнотація:
A novel concept of feedback loop design for modal test and model updating is proposed. This method uses the closed-loop frequency information for parameter modifications to overcome the problems associated with the conventional methods employing the modal sensitivity matrix. To obtain new modal information from the closed-loop system, controllers should be effective in changing modal data while guaranteeing the stability of the closed-loop system. The present paper proposes a mode-decoupling controller that can alter a target mode while guaranteeing the stability of the closed-loop, and that can be constructed by using the measured open-loop, mode shapes. A simulation based on time domain input/output data is performed to evaluate the feasibility of the proposed control method, which is subsequently corroborated via experiments. Experimental data obtained on a beam via the proposed mode-decoupling controller have been applied to estimate thicknesses of a beam. The results show that the proposed approach outperforms conventional methods with a far less number of data set for the estimation of system parameters.
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Jammoussi, H., M. A. Franchek, K. Grigoriadis, and M. Books. "Model Based Control of a Diesel Engine." In ASME 2010 Dynamic Systems and Control Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/dscc2010-4053.
Повний текст джерелаАнотація:
Proposed in this paper is an automated framework for calibration of diesel engine governors. The process involves two basic parts, online engine model identification followed by governor gain design. A previously developed Instrumental Variable 3 Step Algorithm for closed loop system identification is used to estimate the engine model. The identified model is then used in two different governor calibration approaches. The first approach employs a typical governor structure involving acceleration feedback. It will be shown that this governor structure reduces to a classical two degree-of-freedom design. The second approach is based on a procedure in which a desired open-loop transfer function (target transfer function) is shaped such that the same performance specifications as for the first design are satisfied. The control design methods are applied for an off-highway diesel engine with a disengaged transmission. In-field data collected from the engine operating closed-loop is used to identify a model for the open-loop system and the controller gains are then determined. The loop shaping method is then applied to the identified model to design a feedback controller and a prefilter. The efficacy of both loops in terms of tracking performance and noise rejection has been demonstrated through a time domain simulation of both closed-loop step responses.
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Wang, Jeng-Yu, and Masayoshi Tomizuka. "Analysis and Controller Design Based on Linear Model for Heavy-Duty Vehicles." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0322.
Повний текст джерелаАнотація:
Abstract In this paper, we present the time domain, frequency domain and pole/zero analyses of a linearized model of heavy-duty vehicles (tractor-semitrailer type) for lateral control. These analyses are conducted to examine the steering response subject to variations of speed, road adhesion coefficient and look-ahead distance for the lateral position sensor. Based on these analyses, a linear controller for lane following is designed. The close-loop simulation is conducted to show the effectiveness of the linear controller.
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Shakir, Huzefa, and Won-Jong Kim. "Discrete-Time Closed-Loop Model Identification of Fixed-Structure Unstable Multivariable Systems." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41834.
Повний текст джерелаАнотація:
This paper presents improved empirical representations of a general class of open-loop unstable systems using closed-loop system identification. A multi-axis magnetic-levitation (maglev) nanopositioning system with an extended translational travel range is used as a test bed to verify the closed-loop system-identification method proposed in this paper. A closed-loop identification technique employing the Box-Jenkins (BJ) method and a known controller structure is developed for model identification and validation. Direct and coupling transfer functions (TFs) are then derived from the experimental input-output time sequences and the knowledge of controller dynamics. A persistently excited signal with a frequency range of [0, 2500] Hz is used as a reference input. An order-reduction algorithm is applied to obtain TFs with predefined orders, which give a close match in the frequency range of interest without missing any significant plant dynamics. The entire analysis is performed in the discrete-time domain in order to avoid any errors due to continuous-to-discrete-time conversion and vice versa. Continuous-time TFs are used only for order-reduction and performance analysis of the identified plant TFs. Experimental results in the time as well as frequency domains verified the accuracy of the plant TFs and demonstrated the effectiveness of the closed-loop identification and order-reduction methods.
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Zhou, Jinni, Ximin Lyu, Xiaoyu Cai, Zexiang Li, Shaojie Shen, and Fu Zhang. "Frequency domain model identification and loop-shaping controller design for quadrotor tail-sitter VTOL UAVs." In 2018 International Conference on Unmanned Aircraft Systems (ICUAS). IEEE, 2018. http://dx.doi.org/10.1109/icuas.2018.8453475.
Повний текст джерелаЗвіти організацій з теми "Loop domain model"
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Wisniewski, Michael, Samir Droby, John Norelli, Dov Prusky, and Vera Hershkovitz. Genetic and transcriptomic analysis of postharvest decay resistance in Malus sieversii and the identification of pathogenicity effectors in Penicillium expansum. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597928.bard.
Повний текст джерелаАнотація:
Use of Lqh2 mutants (produced at TAU) and rNav1.2a mutants (produced at the US side) for identifying receptor site-3: Based on the fact that binding of scorpion alpha-toxins is voltage-dependent, which suggests toxin binding at the mobile voltage-sensing region, we analyzed which of the toxin bioactive domains (Core-domain or NC-domain) interacts with the DIV Gating-module of rNav1.2a. This analysis was based on the assumption that the dissociation of toxin mutants upon depolarization would vary from that of the unmodified toxin should the substitutions affect a site of interaction with the channel Gating-module. Using a series of toxin mutants (mutations at both domains) and two channel mutants that were shown to reduce the sensitivity to scorpion alpha-toxins, and by comparison of depolarization-driven dissociation of Lqh2 derivatives off their binding site at rNav1.2a mutant channels we found that the toxin Core-domain interacts with the Gating-module of DIV. Details of the experiments and results appear in Guret al (2011). Mapping receptor site 3 at Nav1.2a by extensive channel mutagenesis (Seattle): Since previous studies with photoaffinity labeling and antibody mapping implicated domains I and IV in scorpion alpha-toxin binding, Nav1.2 channel mutants containing substitutions at these extracellular regions were expressed and tested for receptor function by whole-cell voltage clamp. Of a large number of channel mutants, T1560A, F1610A, and E1613A in domain IV had ~5.9-, ~10.7-, and ~3.9-fold lower affinities for the scorpion toxin Lqh2, respectively, and mutant E1613R had 73-fold lower affinity. Toxin dissociation was accelerated by depolarization for both wild-type and mutants, and the rates of dissociation were also increased by mutations T1560A, F1610A and E1613A. In contrast, association rates for these three mutant channels at negative membrane potentials were not significantly changed and were not voltage-dependent. These results indicated that Thr1560 in the S1-S2 loop, Phe1610 in the S3 segment, and Glu1613 in the S3-S4 loop in domain IV participate in toxin binding. T393A in the SS2-S6 loop in domain I also showed a ~3.4-fold lower affinity for Lqh2, indicating that this extracellular loop may form a secondary component of the toxin binding site. Analysis with the Rosetta-Membrane algorithm revealed a three-dimensional model of Lqh2 binding to the voltage sensor in a resting state. In this model, amino acid residues in an extracellular cleft formed by the S1-S2 and S3-S4 loops in domain IV that are important for toxin binding interact with amino acid residues on two faces of the wedge-shaped Lqh2 molecule that are important for toxin action. The conserved gating charges in the S4 transmembrane segment are in an inward position and likely form ion pairs with negatively charged amino acid residues in the S2 and S3 segments (Wang et al 2011; Gurevitz 2012; Gurevitzet al 2013).
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Shai, Yechiel, Arthur Aronson, Aviah Zilberstein, and Baruch Sneh. Study of the Basis for Toxicity and Specificity of Bacillus thuringiensis d-Endotoxins. United States Department of Agriculture, January 1996. http://dx.doi.org/10.32747/1996.7573995.bard.
Повний текст джерелаАнотація:
The report contains three parts which summarizes the three years achievements of the three participating research groups; The Weizmann group, Tel-Aviv group and Purdue group. The firs part describes the achievements obtained by Shai's group toward the elucidation of the mechanism of membrane insertion and the structural organization of the pores formed by the Cry3A and Cry1Ac B. thuringiensis d-endotoxins. For that purpose Shai's group synthesized, fluorescently labeled and structurally and functionally characterized peptides corresponding to the seven helices that compose the pore-forming domain of Cry3A toxin, including mutants peptides and the hairpin a4G-a5 of both Cry3A and Cry 1Ac toxins composed of a4, a5 and the loop connecting a4-a5. Among the synthesized peptides were three mutated a4 helices based on site directed mutagenesis done at Aronson's group that decreased or increased Cry 1Ac toxicity. The results of these studies are consistent with a situation in which only helices a4 anda5 insert into the membrane as a helical hairpin in an antiparallel manner, while the other helices lie on the membrane surface like ribs of an umbrella (the "umbrella model"). In order to test this model Shai's group synthesized the helical hairpin a4<-->a5 of both Cry3A and Cry 1 Ac toxins, as well. Initial functional and structural studies showed direct correlation between the properties of the mutated helices and the mutated Cry1Ac. Based on Shai's findings that a4 is the second helix besides a5 that insert into the membrane, Aronson and colleagues performed extensive mutation on this helix in the CrylAc toxin, as well as in the loop connecting helices 4 and 5, and helix 3 (part two of the report). In addition, Aronson performed studies on the effect of mutations or type of insect which influence the oligomerization either the Cry 1Ab or Cry 1Ac toxins with vesicles prepared from BBMV. In the third part of the report Zilberstein's and Sneh's groups describe their studies on the three domains of Cry 1C, Cry 1E and crylAc and their interaction with the epithelial membrane of the larval midgut. In these studies they cloned all three domains and combinations of two domains, as well as cloning of the pore forming domain alone and studying its interaction with BBMV. In addition they investigated binding of Cry1E toxin and Cry1E domains to BBMV prepared from resistant (R) or sensitive larvae. Finally they initiated expression of the loop a4G<-->a5 Cry3A in E. coli to be compared with the synthetic one done by Shai's group as a basis to develop a system to express all possible pairs for structural and functional studies by Shai's group (together with Y. Shai).
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Eshed-Williams, Leor, and Daniel Zilberman. Genetic and cellular networks regulating cell fate at the shoot apical meristem. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699862.bard.
Повний текст джерелаАнотація:
The shoot apical meristem establishes plant architecture by continuously producing new lateral organs such as leaves, axillary meristems and flowers throughout the plant life cycle. This unique capacity is achieved by a group of self-renewing pluripotent stem cells that give rise to founder cells, which can differentiate into multiple cell and tissue types in response to environmental and developmental cues. Cell fate specification at the shoot apical meristem is programmed primarily by transcription factors acting in a complex gene regulatory network. In this project we proposed to provide significant understanding of meristem maintenance and cell fate specification by studying four transcription factors acting at the meristem. Our original aim was to identify the direct target genes of WUS, STM, KNAT6 and CNA transcription factor in a genome wide scale and the manner by which they regulate their targets. Our goal was to integrate this data into a regulatory model of cell fate specification in the SAM and to identify key genes within the model for further study. We have generated transgenic plants carrying the four TF with two different tags and preformed chromatin Immunoprecipitation (ChIP) assay to identify the TF direct target genes. Due to unforeseen obstacles we have been delayed in achieving this aim but hope to accomplish it soon. Using the GR inducible system, genetic approach and transcriptome analysis [mRNA-seq] we provided a new look at meristem activity and its regulation of morphogenesis and phyllotaxy and propose a coherent framework for the role of many factors acting in meristem development and maintenance. We provided evidence for 3 different mechanisms for the regulation of WUS expression, DNA methylation, a second receptor pathway - the ERECTA receptor and the CNA TF that negatively regulates WUS expression in its own domain, the Organizing Center. We found that once the WUS expression level surpasses a certain threshold it alters cell identity at the periphery of the inflorescence meristem from floral meristem to carpel fate [FM]. When WUS expression highly elevated in the FM, the meristem turn into indeterminate. We showed that WUS activate cytokinine, inhibit auxin response and represses the genes required for root identity fate and that gradual increase in WUCHEL activity leads to gradual meristem enlargement that affect phyllotaxis. We also propose a model in which the direction of WUS domain expansion laterally or upward affects meristem structure differently. We preformed mRNA-seq on meristems with different size and structure followed by k-means clustering and identified groups of genes that are expressed in specific domains at the meristem. We will integrate this data with the ChIP-seq of the 4 TF to add another layer to the genetic network regulating meristem activity.
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Rafaeli, Ada, Russell Jurenka, and Chris Sander. Molecular characterisation of PBAN-receptors: a basis for the development and screening of antagonists against Pheromone biosynthesis in moth pest species. United States Department of Agriculture, January 2008. http://dx.doi.org/10.32747/2008.7695862.bard.
Повний текст джерелаАнотація:
The original objectives of the approved proposal included: (a) The determination of species- and tissue-specificity of the PBAN-R; (b) the elucidation of the role of juvenile hormone in gene regulation of the PBAN-R; (c) the identificationof the ligand binding domains in the PBAN-R and (d) the development of efficient screening assays in order to screen potential antagonists that will block the PBAN-R. Background to the topic: Moths constitute one of the major groups of pest insects in agriculture and their reproductive behavior is dependent on chemical communication. Sex-pheromone blends are utilised by a variety of moth species to attract conspecific mates. In most of the moth species sex-pheromone biosynthesis is under circadian control by the neurohormone, PBAN (pheromone-biosynthesis-activating neuropeptide). In order to devise ideal strategies for mating disruption/prevention, we proposed to study the interactions between PBAN and its membrane-bound receptor in order to devise potential antagonists. Major conclusions: Within the framework of the planned objectives we have confirmed the similarities between the two Helicoverpa species: armigera and zea. Receptor sequences of the two Helicoverpa spp. are 98% identical with most changes taking place in the C-terminal. Our findings indicate that PBAN or PBAN-like receptors are also present in the neural tissues and may represent a neurotransmitter-like function for PBAN-like peptides. Surprisingly the gene encoding the PBAN-receptor was also present in the male homologous tissue, but it is absent at the protein level. The presence of the receptor (at the gene- and protein-levels), and the subsequent pheromonotropic activity are age-dependent and up-regulated by Juvenile Hormone in pharate females but down-regulated by Juvenile Hormone in adult females. Lower levels of pheromonotropic activity were observed when challenged with pyrokinin-like peptides than with HezPBAN as ligand. A model of the 3D structure of the receptor was created using the X-ray structure of rhodopsin as a template after sequence alignment of the HezPBAN-R with several other GPCRs and computer simulated docking with the model predicted putative binding sites. Using in silico mutagenesis the predicted docking model was validated with experimental data obtained from expressed chimera receptors in Sf9 cells created by exchanging between the three extracellular loops of the HezPBAN-R and the Drosophila Pyrokinin-R (CG9918). The chimera receptors also indicated that the 3ʳᵈ extracellular loop is important for recognition of PBAN or Diapause hormone ligands. Implications: The project has successfully completed all the objectives and we are now in a position to be able to design and screen potential antagonists for pheromone production. The successful docking simulation-experiments encourage the use of in silico experiments for initial (high-throughput) screening of potential antagonists. However, the differential responses between the expressed receptor (Sf9 cells) and the endogenous receptor (pheromone glands) emphasize the importance of assaying lead compounds using several alternative bioassays (at the cellular, tissue and organism levels). The surprising discovery of the presence of the gene encoding the PBAN-R in the male homologous tissue, but its absence at the protein level, launches opportunities for studying molecular regulation pathways and the evolution of these GPCRs. Overall this research will advance research towards the goal of finding antagonists for this important class of receptors that might encompass a variety of essential insect functions.
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Christopher, David A., and Avihai Danon. Plant Adaptation to Light Stress: Genetic Regulatory Mechanisms. United States Department of Agriculture, May 2004. http://dx.doi.org/10.32747/2004.7586534.bard.
Повний текст джерелаАнотація:
Original Objectives: 1. Purify and biochemically characterize RB60 orthologs in higher plant chloroplasts; 2. Clone the gene(s) encoding plant RB60 orthologs and determine their structure and expression; 3. Manipulate the expression of RB60; 4. Assay the effects of altered RB60 expression on thylakoid biogenesis and photosynthetic function in plants exposed to different light conditions. In addition, we also examined the gene structure and expression of RB60 orthologs in the non-vascular plant, Physcomitrella patens and cloned the poly(A)-binding protein orthologue (43 kDa RB47-like protein). This protein is believed to a partner that interacts with RB60 to bind to the psbA5' UTR. Thus, to obtain a comprehensive view of RB60 function requires analysis of its biochemical partners such as RB43. Background & Achievements: High levels of sunlight reduce photosynthesis in plants by damaging the photo system II reaction center (PSII) subunits, such as D1 (encoded by the chloroplast tpsbAgene). When the rate of D1 synthesis is less than the rate of photo damage, photo inhibition occurs and plant growth is decreased. Plants use light-activated translation and enhanced psbAmRNA stability to maintain D1 synthesis and replace the photo damaged 01. Despite the importance to photosynthetic capacity, these mechanisms are poorly understood in plants. One intriguing model derived from the algal chloroplast system, Chlamydomonas, implicates the role of three proteins (RB60, RB47, RB38) that bind to the psbAmRNA 5' untranslated leader (5' UTR) in the light to activate translation or enhance mRNA stability. RB60 is the key enzyme, protein D1sulfide isomerase (Pill), that regulates the psbA-RN :Binding proteins (RB's) by way of light-mediated redox potentials generated by the photosystems. However, proteins with these functions have not been described from higher plants. We provided compelling evidence for the existence of RB60, RB47 and RB38 orthologs in the vascular plant, Arabidopsis. Using gel mobility shift, Rnase protection and UV-crosslinking assays, we have shown that a dithiol redox mechanism which resembles a Pill (RB60) activity regulates the interaction of 43- and 30-kDa proteins with a thermolabile stem-loop in the 5' UTR of the psbAmRNA from Arabidopsis. We discovered, in Arabidopsis, the PD1 gene family consists of II members that differ in polypeptide length from 361 to 566 amino acids, presence of signal peptides, KDEL motifs, and the number and positions of thioredoxin domains. PD1's catalyze the reversible formation an disomerization of disulfide bonds necessary for the proper folding, assembly, activity, and secretion of numerous enzymes and structural proteins. PD1's have also evolved novel cellular redox functions, as single enzymes and as subunits of protein complexes in organelles. We provide evidence that at least one Pill is localized to the chloroplast. We have used PDI-specific polyclonal and monoclonal antisera to characterize the PD1 (55 kDa) in the chloroplast that is unevenly distributed between the stroma and pellet (containing membranes, DNA, polysomes, starch), being three-fold more abundant in the pellet phase. PD1-55 levels increase with light intensity and it assembles into a high molecular weight complex of ~230 kDa as determined on native blue gels. In vitro translation of all 11 different Pill's followed by microsomal membrane processing reactions were used to differentiate among PD1's localized in the endoplasmic reticulum or other organelles. These results will provide.1e insights into redox regulatory mechanisms involved in adaptation of the photosynthetic apparatus to light stress. Elucidating the genetic mechanisms and factors regulating chloroplast photosynthetic genes is important for developing strategies to improve photosynthetic efficiency, crop productivity and adaptation to high light environments.