Dissertations / Theses on the topic 'Wald Entropy'

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
Includes bibliographical references (leaves 81-86).
Graphical models provide a powerful formalism for statistical signal processing. Due to their sophisticated modeling capabilities, they have found applications in a variety of fields such as computer vision, image processing, and distributed sensor networks. In this thesis we study two central signal processing problems involving Gaussian graphical models, namely modeling and estimation. The modeling problem involves learning a sparse graphical model approximation to a specified distribution. The estimation problem in turn exploits this graph structure to solve high-dimensional estimation problems very efficiently. We propose a new approach for learning a thin graphical model approximation to a specified multivariate probability distribution (e.g., the empirical distribution from sample data). The selection of sparse graph structure arises naturally in our approach through the solution of a convex optimization problem, which differentiates our procedure from standard combinatorial methods. In our approach, we seek the maximum entropy relaxation (MER) within an exponential family, which maximizes entropy subject to constraints that marginal distributions on small subsets of variables are close to the prescribed marginals in relative entropy. We also present a primal-dual interior point method that is scalable and tractable provided the level of relaxation is sufficient to obtain a thin graph. A crucial element of this algorithm is that we exploit sparsity of the Fisher information matrix in models defined on chordal graphs. The merits of this approach are investigated by recovering the graphical structure of some simple graphical models from sample data. Next, we present a general class of algorithms for estimation in Gaussian graphical models with arbitrary structure.
(cont.) These algorithms involve a sequence of inference problems on tractable subgraphs over subsets of variables. This framework includes parallel iterations such as Embedded Trees, serial iterations such as block Gauss-Seidel, and hybrid versions of these iterations. We also discuss a method that uses local memory at each node to overcome temporary communication failures that may arise in distributed sensor network applications. We analyze these algorithms based on the recently developed walk-sum interpretation of Gaussian inference. We describe the walks "computed" by the algorithms using walk-sum diagrams, and show that for non-stationary iterations based on a very large and flexible set of sequences of subgraphs, convergence is achieved in walk-summable models. Consequently, we are free to choose spanning trees and subsets of variables adaptively at each iteration. This leads to efficient methods for optimizing the next iteration step to achieve maximum reduction in error. Simulation results demonstrate that these non-stationary algorithms provide a significant speedup in convergence over traditional one-tree and two-tree iterations.
by Venkat Chandrasekaran.
S.M.

Thesis (M.S.)--University of Missouri-Columbia, 2005.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 23, 2007) Includes bibliographical references.

Ground penetrating radar (GPR) has been extensively utilized as a highly efficient and non-destructive testing method for infrastructure evaluation, such as highway rebar detection, bridge decks inspection, asphalt pavement monitoring, underground pipe leakage detection, railroad ballast assessment, etc. The focus of this dissertation is to investigate the key techniques to tackle with GPR signal processing from three perspectives: (1) Removing or suppressing the radar clutter signal; (2) Detecting the underground target or the region of interest (RoI) in the GPR image; (3) Imaging the underground target to eliminate or alleviate the feature distortion and reconstructing the shape of the target with good fidelity. In the first part of this dissertation, a low-rank and sparse representation based approach is designed to remove the clutter produced by rough ground surface reflection for impulse radar. In the second part, Hilbert Transform and 2-D Renyi entropy based statistical analysis is explored to improve RoI detection efficiency and to reduce the computational cost for more sophisticated data post-processing. In the third part, a back-projection imaging algorithm is designed for both ground-coupled and air-coupled multistatic GPR configurations. Since the refraction phenomenon at the air-ground interface is considered and the spatial offsets between the transceiver antennas are compensated in this algorithm, the data points collected by receiver antennas in time domain can be accurately mapped back to the spatial domain and the targets can be imaged in the scene space under testing. Experimental results validate that the proposed three-stage cascade signal processing methodologies can improve the performance of GPR system.

The growing importance of emerging markets in the global economy leads many multinationals (MNEs) to explore and expand into them. Saturation and slow growth in home markets, coupled with rising incomes in emerging markets, has also accelerated retail internationalisation. These markets are generally unfamiliar to the predominantly western firms, and they come with intractable social problems, where resultant stakeholder activism abounds.The purpose of this study was to investigate stakeholder management during entry of a retailer, Wal-Mart, into an emerging market, South Africa, in order to draw lessons that could be of use to other MNEs seeking to enter similar emerging markets. The method used for the study was a qualitative archival analysis that relied on publicly available sources, namely the regulatory bodies, parliament, press releases and the print media.The research found that the key stakeholders during the entry of Wal-Mart into South Africa were the government and trade unions. Government and trade unions were concerned that Wal-Mart’s entry would lead to an increase in imports and displace local producers, in turn worsening South Africa’s unemployment crisis. It was also feared that Wal-Mart would seek to change the existing labour regime in order to marginalise trade unions and lower labour standards. The research found that stakeholder management was poor and highlights the importance of integrating stakeholder management strategy into the broader entry strategy into developing markets.
Dissertation (MBA)--University of Pretoria, 2012.
Gordon Institute of Business Science (GIBS)
unrestricted

Con il testo presente, si intende mostrare come i gradi di libertà associati all'entropia di un buco nero possano essere ricercati in parte fruttuosamente nell'interazione dei campi quantistici con la struttura causale e geometrica esibita da un buco nero. Nel Capitolo 1, si affrontano le principali caratteristiche dei buchi neri alla luce della teoria classica di Relatività Generale: sono analizzate la soluzione di Schwarzschild e la struttura causale nello spazio-tempo conseguente, discutendo le definizioni di orizzonte e di singolarità e il rapporto che le lega, con riferimento ai risultati di Penrose e Hawking. Introdotto, all'inizio del Capitolo 2, il concetto di gravità superficiale e la metrica di Kerr-Newman, si studia il significato delle Quattro Leggi dei buchi neri, valide per soluzioni stazionarie. Il Capitolo 3 espone quali motivazioni spingano a proporre una caratterizzazione termodinamica dei buchi neri, attribuendovi una temperatura e un'entropia (detta “di Bekenstein-Hawking”) di natura geometrica, dipendente dall'area dell'orizzonte; si trattano qui i problemi che si incontrano nel costruire una corrispondente Meccanica Statistica. Si descrive dunque in quali termini il processo di radiazione di Hawking riesca a dare una spiegazione fisica della temperatura, e si rileva la presenza, secondo osservatori statici, di un'atmosfera termica nei pressi dell’orizzonte. Infine, si esamina la possibilità di attribuire alla radiazione di Hawking i gradi di libertà relativi all'entropia di Bekenstein-Hawking. In particolare, si illustra il modello a muro di mattoni di 't Hooft, che lega i gradi di libertà all'atmosfera termica. Considerando infine la deformazione dell'orizzonte dovuta a fluttuazioni quantistiche, si giunge alla conclusione che l'entropia dell'atmosfera termica rappresenta non un'interpretazione dell'entropia di Bekenstein-Hawking, bensì una sua correzione al secondo ordine.

This thesis began as an exploration of the idea of home, a study that revealed the importance of place. Seeking to understand what makes a successful place, I studied neighborhoods with which I was familiar, identifying characteristics of both the vital and the lifeless. As a foundation for architectural exploration, this study helped me to recognize the dynamic qualities of denser, more urban neighborhoods, and to establish rowhousing as the vehicle through which to undertake my exploration of urban living. While providing the genesis for the project and further defining certain elements as worthy of further study, this initial exploration was nonetheless lacking. I had to do more than just speak of the conditions I hoped to achieve and of the characteristics of the elements with which to make the conditions manifest. I had to make the conditions, make the elements. It was essential for me to establish a clear order, so that these conditions could be brought together to form a cohesive whole. I was able to arrive at a fully conceived expression of the project by structuring the conditions that I identified through the application of three dimensional grids. The interrelationships among the grids helped structure the relationships among various conditions, ensuring that they enhanced one another, and were, in fact, stronger together than separately. Working with the grids taught me that in order for them to be effective regulators the grids had to be intelligible while still being flexible; that they should help define but never dictate. It exposed the tension between the regulating devices we, as architects, utilize as tools for design and the three-dimensional material with which the designs are constructed, as well as the obligation of reconciling the two. Not only must the device accommodate the material and the material reveal the device, but indeed all facets of the design must be considered in relation to one another and to the whole. When philosopy, device, and material work in service of one another the possibility for architectural expression rather than simple building is created. One does not revere great architects solely for their philosophies of design, the functionality of the spaces they create, the materials with which they construct them, or the regulating devices they employ, but rather for the complexity with which these elements are brought together to form a whole so well designed that it seems that it could have been done no other way.
Master of Architecture

The key objective of this thesis is the outline of an alternative capital market modeling framework, the Volatility Asset Pricing Model, VAPM, inspired by the innovative dual approach of Mandelbrot and Hudson using the method based on synthesis of two seemingly antagonistic factors -- the volatility of market prices and their serial dependence determining the capital markets' dynamics. The pilot tests of this model in various periods using the market index as well as a portfolio of selected securities delivered generally satisfactory results. Firstly, the work delivers a brief recapitulation regarding the concepts of a consumer/investor choice under general conditions of hypothetical certainty. Secondly, this outline is then followed by a description of the "classical" methodologies in the risky environment of uncertainty, with assessment of their corresponding key models, i.e. the CAPM, SIM, MIM, APTM, etc., notwithstanding results of the related testing approaches. Thirdly, this assessment is based on evaluation of the underlying doctrine of Efficient Market Hypothesis in relation to the so called Random Walk Model. Fourthly, in this context the work also offers a brief exposure to a few selected tests of these contraversial concepts. Fifthly, the main points of conteporary approaches such as the Fractal Dimension and the Hurst Exponent in the dynamic framework of information entropy are subsequently described as the theoretical tools leading to development of the abovementioned model VAPM. The major contribution of this thesis is considered its attempt to apply the abovementioned concepts in practice, with the intention to possibly inspire a further analytical research.

thresh-old noun `thresh-`hold, `thre-`shold _the sill of a doorway _the entrance to a house or building _any place or point of entering or beginning A threshold can be understood as the visible or invisible division and demarcation of space. It is an age-old concept tracing back even to the first notions of urban space. The largest scaled gestures of thresholds are those lines and walls that divide nations and territories. All complexities of past and current geopolitical tensions simply derive from the interpretations and implementation of the walls and geopolitical lines or lineaments. It is therefore crucial to comprehend the concept of lineaments on every scale, as it is the base idea that permeates all design. It is design in its purest form. The following architectural argument will explore Leon Battista Albert's theory of lineaments, particularly the wall as an architectural element, as he spells out in his architectural treatise On the Art of Building in Ten Books. A closer look at Alberti's treatise and the idea of lineaments will help to better refine the definition and implementation of international borders and treatises. Reconsideration of a lineament in the slightest form has the potential to drastically change the execution and enforcement of a lineament in tangible materials and their assembly during construction. The chosen design proposes a new U.S.-Mexico Joint Land Port of Entry along the border of Columbus, New Mexico, United State of America, and Puerto Palomas, Chihuahua, Mexico
Master of Architecture

In dieser Arbeit werden verschieden Ansätze diskutiert, die zum Verständnis und zur Beschreibung anomalen Diffusionsverhaltens beitragen, wobei insbesondere zwei unterschiedliche Aspekte hervorgehoben werden. Zum einen wird das Entropieproduktions-Paradoxon beschrieben, welches bei der Analyse der Entropieproduktion bei der anomalen Diffusion, beschrieben durch fraktionale Diffusionsgleichungen auftritt. Andererseits wird ein detaillierter Vergleich zwischen Lösungen verallgemeinerter Diffusionsgleichungen mit numerischen Daten präsentiert, die durch Iteration der Mastergleichung auf verschiedenen Fraktalen produziert worden sind. Die Entropieproduktionsrate für superdiffusive Prozesse wird berechnet und zeigt einen unerwarteten Anstieg beim Übergang von dissipativer Diffusion zur reversiblen Wellenausbreitung. Dieses Entropieproduktions-Paradoxon ist die direkte Konsequenz einer anwachsenden intrinsischen Rate bei Prozessen mit zunehmendem Wellencharakter. Nach Berücksichtigung dieser Rate zeigt die Entropie den erwarteten monotonen Abfall. Diese Überlegungen werden für generalisierte Entropiedefinitionen, wie die Tsallis- und Renyi-Entropien, fortgeführt. Der zweite Aspekt bezieht sich auf die anomale Diffusion auf Fraktalen, im Besonderen auf Sierpinski-Dreiecke und -Teppiche. Die entsprechenden Mastergleichungen werden iteriert und die auf diese Weise numerisch gewonnenen Wahrscheinlichkeitsverteilungen werden mit den Lösungen vier verschiedener verallgemeinerter Diffusionsgleichungen verglichen.

The thesis is focused on newly built home for the elderly people in cadastre of Vlkanec village, in Kutna Hora district. The building area is rectangular shaped, with entrance to the area situated from local tarmac road. The house is designed for barrier-free housing of forty people in twenty- six apartments. The house includes common area for providing services for local residents and residents of neighboring villages. The services provided are to be catering services, general practitioner’s office and hair/nail salon. The object consists of service building, living facilities, joined to main building as a left and a right wing and adjacent terraces. The living facilities have three floors (cellarage and two above floors). The utilities, such as laundry room, drying room, boiler room, are situated in the cellar, the apartments and the common areas are in two above-ground floors. Architectural solution of the house is outlined so it uses mostly traditional natural building material (brick, stone, wood, metal) in its inherit color. Furthermore, the project is dealing with rain water management, local communications, such as the road, car park and pavements.

In this thesis, we propose many developments in the context of Structural Similarity. We address both node (local) similarity and graph (global) similarity. Concerning node similarity, we focus on improving the diffusive process leading to compute this similarity (e.g. Commute Times) by means of modifying or rewiring the structure of the graph (Graph Densification), although some advances in Laplacian-based ranking are also included in this document. Graph Densification is a particular case of what we call graph rewiring, i.e. a novel field (similar to image processing) where input graphs are rewired to be better conditioned for the subsequent pattern recognition tasks (e.g. clustering). In the thesis, we contribute with an scalable an effective method driven by Dirichlet processes. We propose both a completely unsupervised and a semi-supervised approach for Dirichlet densification. We also contribute with new random walkers (Return Random Walks) that are useful structural filters as well as asymmetry detectors in directed brain networks used to make early predictions of Alzheimer's disease (AD). Graph similarity is addressed by means of designing structural information channels as a means of measuring the Mutual Information between graphs. To this end, we first embed the graphs by means of Commute Times. Commute times embeddings have good properties for Delaunay triangulations (the typical representation for Graph Matching in computer vision). This means that these embeddings can act as encoders in the channel as well as decoders (since they are invertible). Consequently, structural noise can be modelled by the deformation introduced in one of the manifolds to fit the other one. This methodology leads to a very high discriminative similarity measure, since the Mutual Information is measured on the manifolds (vectorial domain) through copulas and bypass entropy estimators. This is consistent with the methodology of decoupling the measurement of graph similarity in two steps: a) linearizing the Quadratic Assignment Problem (QAP) by means of the embedding trick, and b) measuring similarity in vector spaces. The QAP problem is also investigated in this thesis. More precisely, we analyze the behaviour of $m$-best Graph Matching methods. These methods usually start by a couple of best solutions and then expand locally the search space by excluding previous clamped variables. The next variable to clamp is usually selected randomly, but we show that this reduces the performance when structural noise arises (outliers). Alternatively, we propose several heuristics for spanning the search space and evaluate all of them, showing that they are usually better than random selection. These heuristics are particularly interesting because they exploit the structure of the affinity matrix. Efficiency is improved as well. Concerning the application domains explored in this thesis we focus on object recognition (graph similarity), clustering (rewiring), compression/decompression of graphs (links with Extremal Graph Theory), 3D shape simplification (sparsification) and early prediction of AD.
Ministerio de Economía, Industria y Competitividad (Referencia TIN2012-32839 BES-2013-064482)

One of the recent fundamental developments in theoretical high energy physics is the AdS/CFT correspondence [1, 2, 3, 4] which posits a relationship between Quantum Field Theories (QFT) in a given dimension and String Theory on a higher dimensional anti- de Sitter (AdS) spacetime. This has revolutionised our understanding of QFTs (more speci fically conformal fi eld theories (CFTs)) and string theory/gravity, and has far reaching consequences for explorations into a vast array of physical phenomena. Using the elegant formalism provided by this powerful duality, often called \holography", one can now use fundamental physical observables in QFT to better understand the nature of quantum gravity. The theoretical tools provide a translation of calculable field theoretic observables into the language of gravity thereby leading to the construction of holographic models for several interesting QFTs. Entanglement is a fundamental physical property of all quantum systems. From models of various condensed matter systems to its application as a tool for secure and fast communication in quantum information theory [5], it serves as an intersection point between different subfi elds of physics [6]. From the AdS/CFT point of view quantum entanglement connects geometry with quantum information, providing a window to understand how the bulk gravity physics emerges from the holographic fi eld theoretic viewpoint. Probing various aspects of this connection in detail will be the broad theme of this thesis. For extended, many-body systems, the most well known measure of quantum entanglement is the \Entanglement Entropy" (EE) which is also the best understood measure within the holographic framework. In early 2006, Ryu and Takayanagi (RT) gave a simple and elegant prescription for computing this quantity using AdS/CFT duality within Einstein gravity [7, 8]. They proposed that EE for a subsystem within an extended system (QFT), is computed by the (proper) area of a static, codimension- 2, \extremal" surface inside the dual AdS spacetime. The RT proposal has passed several non-trivial consistency checks, for example strong sub-additivity, area law to name a few [9]. A remarkable aspect of the proposal is the ease with which EE can now be calculated, while it is well known that obtaining EE from fi rst principles in QFT presents several technical challenges which have so far been surmounted only in some 2d fi eld theories using the \replica method" [10, 11, 12]. The most intriguing aspect of the RT proposal is its striking similarity to Bekenstein- Hawking (BH) entropy which is proportional to the area of a black hole horizon, further confi rming an intimate relationship between entropy and geometry [13, 14, 15, 16]. This leads to the natural question: what is the connection between EE and BH entropy? This question has been sharpened recently by Lewkowycz and Maldacena (LM) via the concept of Generalized Gravitational Entropy which extends the QFT replica trick to a replica symmetry for the dual space-time [17]. This was used to prove the RT conjecture successfully by deriving the correct extremal surface equation for two derivative gravity theories. In this thesis I have studied the generalization of LM method for higher derivative gravity theories [18, 19, 20, 21, 22, 23] describing holographic duals (of QFT's with fi nite number of colours) and fi nite 't Hooft coupling which takes the AdS/CFT correspondence beyond the usual supergravity limit. If one wants to use AdS/CFT to study real life systems then it is absolutely necessary to incorporate the nite coupling effect into the theory and hence the study of higher derivative effects becomes very important. In these two papers [21, 22] I have formulated a proof for the existence of the entropy functionals for certain higher derivative theories extending LM method. We have shown that the for a certain special class of higher derivative theories there exist well de fined entropy functionals. To extend this proof for more general theories of gravity opens up a possibility of breaking replica symmetry in the bulk space-time [24]. For higher derivative gravity, black hole entropy for a large class of stationary black holes with bifurcate killing horizon is given by the well known Wald prescription [25, 26, 27] which relates the concept of the Noether charge with the black hole entropy. Iyer and Wald proposed a generalization for dynamical horizons. This throws up the question whether there is a relation between these EE functionals and the Noether charge, and whether we can derive them using the approach of Iyer and Wald. For a certain class of theories I have shown that there exists a relation between these two [28] but a more rigorous proof is needed. This somewhat fi rms up the area-entropy relation for arbitrary surfaces and proves the existence of holographic EE functionals for higher curvature theories thereby extending the applicability of Iyer-Wald formalism beyond the bifurcation surface. Apart from this, it is well known that there exist several measures of quantum entanglement, each satisfying a variety of mathematical inequalities and conditions [5]. Translating these into the language of holography constrains the dual gravity theory and will lead to general statements about the consistency of the theory. In this thesis I have discussed one such measure namely Relative entropy [29], the positivity of which has led to constraints on the underlying gravity theory [30]. Also entanglement entropy is a very useful tools for probing renormalization group (RG) flow from the holographic point of view [34, 31, 32, 35, 33]. We end with exploring the concept of renormalized entanglement entropy [36, 37] and its application in probing RG flow in the context of N = 2 gauged supergravity [38]. References [1] J. M. Maldacena, \The large N limit of superconformal eld theories and supergravity," Adv. Theor. Math. Phys. 2, 231 (1998), [arXiv:hep-th/9711200]

碩士
國立成功大學
機械工程學系
89
Abstract This study main employ “Second Law of Thermodynamics (Entropy generation)“viewpoint and Local (Average) Nusselt number to analysis the effects of incompressible laminar channel flow fluid, wall heat transfer characteristics and friction coefficient with Wall-Attached and Wall-Detached Heated Blocks and staggered or in-line blocks. The governing equations are solved by a Finite-volume-based Finite-Element method .In this study, no-stagger grid or collocation are used to solve the Navier-Stokes equations. The parameters interested include (1) entrance Reynolds number (Re), (2) the ratio of block height to channel height (H/2B), (3) the distance between two blocks staggered (S/H), (4) the ratio of interval (blocks detached from wall) to channel height (C/H). Moreover, the enhancement in heat transfer is accompanied with increase in the friction loss to fluid flow. The reduce friction loss and increase heat transfer reach balance. We suppose to discuss the optimum efficient. For a heated flow field, a constant heated wall temperature is considered along blocks. The distributions of heat transfer coefficient and the physical phenomena of this flow field are presented.

碩士
龍華科技大學
機械系碩士班
92
In the present paper, the laminar convection and entropy generation in a helical coil with constant wall heat flux are numerically investigated. Both of the entrance region and the fully developed region are included. The studied cases cover a Reynolds number range from 1000 to 7500, and wall heat flux of 160, 320 and 640 w/m and curvature ratio =0.07, 0.11, 0.15, 0.2. The development of the flow fields, including the secondary flow motion, distributions of temperature, Nusselt number and friction factor are given and discussed. In particular, the distributions of the entropy generation rate in the helical coil are especially highlighted. According to the minimum entropy generation principle and the thermodynamic second law, the analysis of the optimal Reynolds number and coiled tube size for the helical coil flow with constant wall heat flux is carried out. The optimal Re and coiled tube size should be chosen as the flow operating condition so that the thermal system could have the least irreversibility and the best exergy utilization. In addition, about the part of natural convection for helical coil, we’re going to study the effects of different angle of inclination positions on the coefficient of heat transfer and entropy generation.

博士
國立中興大學
物理學系所
97
It''s a known fact that driven Brownian transport through a geometrical landscape exhibits characteristic dependence of current and diffusion upon both temperature and a driving force as well as a remarkable existence of a scaling regime. From a different standpoint, this paper has investigated a neat random-walk model aiming at uniformly-driven transports under geometrical confinement and yet subject to discrete description. The results show that in this discrete modeling, some of those representative characteristcs of entropic transport retain while the others, such as scaling behavior, don''t. In addition, two characteristics are observed which do not exist in the continuous model: a reverse dependence of current on noise strengths, and the existence of mobility optimization.

碩士
國立高雄應用科技大學
模具工程系碩士班
94
This thesis focuses on the thermodynamic second law analysis of saturated vapor flowing slowly onto and condensing on an elliptical tube with variable wall temperature. An entropy generation minimization, EGM, technique is applied as a unique measure to study the thermodynamic losses caused by heat transfer and film flow friction for the laminar film condensation on a non-isothermal horizontal elliptical tube. The results provide us how the geometric parameter-ellipticity and the amplitude of non-isothermal wall temperature variation affect entropy generation during film-wise condensation heat transfer process. From the second law point of view, entropy generation increases with increasing the value of ellipticity. Meanwhile, thermal irreversibility dominates over film flow friction irreversibility. Finally, the optimal design can be achieved by analyzing entropy generation in film condensation on a horizontal elliptical tube with further account for the amplitude of non-isothermal wall temperature variation.

碩士
國立高雄應用科技大學
模具工程系碩士班
96
Abstract This paper uses thermodynamic second law to perform entropy generation analysis for saturated vapor flowing slowly onto and being condensed on a horizontal tube with uniform wall heat flux. Based on entropy generation theory and film condensation heat transfer analysis, the effects of various parameters as Brinkman number, Rayleigh number, Peclet number and irreversibility ratio on local entropy generation rate are investigated The result shows that local entropy generation rate increases with Brinkman group parameters. As Rayleigh group parameters increase, dimensionless heat transfer coefficient is enhanced, but entropy generation number is augmented too. The heat transfer irreversibility dominates the system of entropy generation. In addition condition of flow suction at the porous wall is also studied and compared with that of no suction effect . . Keywords: Entropy, Uniform wall heat flux, Film condensation, Tube,suction

Quiescence, a transitory period of non-growth, is a ubiquitous aspect that is present in all organisms. In addition to being present in all forms of life, quiescence is a feature that has been observed in cells that are important for human health, including stem cells in mammals and antibiotic tolerant cells in bacteria. In bacteria, quiescence per se has recently been suggested to underlie the transient tolerance to a wide range of antibiotics. Furthermore, most microbial life exists in a quiescent state. Despite their prevalence and importance, relatively little is known about the physiology of quiescent bacteria. One aspect of bacterial quiescence that has been repeatedly observed is their lowered metabolic activity compared to actively growing bacteria. How do cells that grow and divide enter into a temporary state of non-growth? In particular, how are the energy-intensive processes that are required for growing cells regulated during a non-growing state? The main subject of this thesis is to investigate how protein synthesis, the most energy-intensive process in growing bacterial cells, is regulated during entry into a quiescent phenotype (stationary phase). I first investigate how protein synthesis is regulated using a single cell method that fluorescently tags nascent polypeptide chains. In chapter 3, I show that during entry into stationary phase, protein synthesis is downregulated heterogeneously with one group of cells having comparatively low protein synthesis, resulting in a population that is approximately bimodal. I further show that this bimodality is dependent on a signaling system (PrkC and its partner phosphatase PrpC) that senses cell wall metabolism. I connect signaling from this system to the expression of an enzyme (SasA) that produces a group of nucleotides that are major regulators of growth in bacteria ((pp)pGpp). Lastly, I show that the bimodality is dependent on the three enzymes that synthesize (pp)pGpp. In chapter 4, I explore in detail how the bimodality in protein synthesis is generated. This heterogeneity requires the production of (pp)pGpp by three synthases: SasA, SasB, RelA. I first show that these enzymes differentially affect this bimodality: RelA and SasB are necessary to generate the sub-population exhibiting low protein synthesis, whereas SasA is necessary to generate cells exhibiting comparatively higher protein synthesis. The RelA product (pppGpp) allosterically activates SasB, and I find that the SasA product (pGpp) competitively inhibits this activation. I provide in vivo evidence that this antagonistic interaction mediates the observed heterogeneity in protein synthesis. This chapter, therefore, identifies the mechanism underlying the generation of phenotypic heterogeneity in the central physiological process of protein synthesis. In chapter 5, I next turn to understand the biochemical mechanism by which cells with comparatively low levels of protein synthesis down-regulate this process. I first show that ppGpp is sufficient to inhibit protein synthesis in vivo. I then show that ppGpp inhibits protein synthesis by inhibiting translation initiation directly by binding to the essential GTPase, Initiation Factor 2 (IF2). In collaboration with Ruben Gonzalez’s lab, we also show that ppGpp prevents the allosteric activation of IF2. Finally, I demonstrate that the observed attenuation of protein synthesis during the entry into quiescence is a consequence of the direct interaction of (pp)pGpp and IF2.

碩士
國立臺灣大學
法律學研究所
107
This is a study on regulations regarding mountain entry in Taiwan. First, the thesis reviews all acts concerning mountain entry, and finds out that there are 11 different types of acts regulating mountain entry. After reviewing all acts in detail, including regulated areas, measures, procedure of application, application requirements, legal effect of violation, and so on, the thesis finds out that most acts regulate it through permission, there are even acts totally prihibiton of mountain entry. As a result, the thesis must to discuss furthermore about the constitutionality of such acts. With respect to fundamental rights of mountain entry, the thesis trys to introduce “Betretungsrecht”, or the right to walk-in, which is a legal term from Germany, and localizes it, in order to suit more smoothly, and enlists it as one of unenumerated fundamental rights. Then with respect to the purpose of regulations, this thesis concludes that there are 7 purposes. With further discussion of whether it’s legitimate, this thesis agrees with the purpose of protection of environment, preservation of culture, safty of life and health, etc, are legitimate. However, surveillance of indigenous isn’t legitimate. Concerning to the measure of regulations, the thesis clearifys three levels of regulation structures in the beginning, and then focus on the regulation of permission and notice. On the analysis of permit system, the issues discuss here including: national security isn’t a suitable aim, but protection of environment, preservation of culture, and protection of life and health are suitable aim; permit system isn’t necessary measure to achieve aim of social order, but it’s necessary measure to achieve aim of environmental protection. On the analysis of notice system, the issues discuss here including: notice system isn’t necessary measure to achieve aim of social order, but it’s necessary measure to achieve aim of life and health protection. Finally, the thesis makes holistic recommendations about regulation of mountain entry. That is, structure one needs to empower people to participate in forming regulated area, and promotes the unification of different kind of environmental reserves; structure two needs to guarantee the right to walk-in, and follows principles and standards to establish permit and notice system, including procedures and substantial requirements; structure three needs to adopt administrative sanction rather than criminal penalty. In conclusion, the thesis points out the errors in these acts respectively, and makes specific recommendations according to the principles and standards this thesis underlining.