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Sroan, Baninder Singh. "Mechanism of gas cell stability in bread making." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/338.
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Davoodi, Jamshid. "Bacillus circulans xylanase: Stability and mechanism of action." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10216.
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The stability and mechanism of the action of the enzyme Bacillus circulans xylanase (1,4-$\beta$-D-xylanohydrolase, EC 3.2.1.8) were investigated by various biophysical techniques. On the basis of the sequence homology between B. circulans xylanase and xylanase A from Schizophyllum commune, a disulphide bond was introduced between the residues 100 and 148, S100C/N148C (DS1 mutant). The presence of this covalent cross-link leads to a 5$\sp\circ$C increase in the melting point of the protein, as verified by differential scanning calorimetry. Introduction of another disulphide bond in a similar position, V98C/A152C, the DS2 mutant also enhances the stability of the protein by as much as 4$\sp\circ$C. On the basis of the notion that the increase in the stability of a protein is proportional to the number of residues encompassed by the cross-link, the N and C-termini were joined, A1GC/G187,C188, to form the circular xylanase (cXI) mutant. This mutant also acquired a 3.8$\sp\circ$C elevated melting point. A combination of S100C/N148C and A1GC/G187,C188 mutations is accompanied by a 12.3$\sp\circ$C increase in the melting point, which is 3.5$\sp\circ$C more than expected. Thus, the stabilization effect of the two disulphide bonds appears to be cooperative rather than additive. Moreover, the thermodynamic data obtained from differential scanning calorimetry under reversible conditions support previous findings that the stabilizing effect of disulphide bonds is a consequence of a decreased conformational entropy of the unfolded state. Furthermore, the results of this study support the notion that the introduction of a disulphide bond can be used as a strategy to prevent the aggregation of proteins by restricting the exposure of some elements required for this process. The active site of Bacillus circulans xylanase contains two acidic residues, glutamic acids 78 and 172, which are crucial for the catalytic activity of the enzyme. Fourier-transform infrared and near-UV circular dichroism spectroscopies were used to determine the pK$\rm\sb{a}$ of these residues. For the wild type enzyme, a titration of one of carboxylate groups occurs at pH 6.8, as evidenced by FT-IR spectroscopy. This titration is absent in the E78Q of E172Q variants of the enzyme. This, taken with crystallographic data, indicates that glutamic acid at position 172 has an abnormally high pK$\rm\sb{a}$ of 6.8. The high pK$\rm\sb{a}$ value of Glu 172 is caused largely by electrostatic interactions of this residue with a proximal glutamic acid at position 78. Furthermore, the circular dichroism spectrum of the wild type xylanase shows a structural transition at pH 4.9 in the near-UV region which is absent for the E78C mutant. This taken with the fact that glutamic acid 78 forms a network of hydrogen bonds with tyrosine 69 and tryptophan 71 indicates that the transition with pK$\rm\sb{a}$ 4.9 should be attributed to glutamic acid 78. The presence of two proximal carboxyl groups, from glutamic acids 78 and 172, results in a pH-dependent destabilisation of the protein structure as evidenced by differential scanning calorimetry experiments, with the wild type xylanase and a number of mutant proteins.
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Pei, Fen, and Fen Pei. "Cell-Based Mechanism Mediating Prion Loss and Stability." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626311.
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The prion protein underlies several previously inexplicable phenomena, including transmissible neurodegenerative disease in mammals and the non-Mendelian inheritance of unique traits in fungi. These proteins can adopt multiple stable conformations, and each of these forms can self-replicate by assembling into ordered aggregates, which template the conversion of the newly synthesized protein into the prion form as these monomers join the aggregates. These complexes must then be fragmented to generate additional templates and to promote the spread of the aggregates both within and between individuals. Despite its efficient and autocatalytic pathways of protein misfolding, changes in prion self-replication cycles can inhibit prion persistence and thus the transmission of prion-associated phenotypes. In our studies, we first explored this inhibition process using a yeast prion [PSI+], the prion form of a translation termination factor Sup35, and a dominant-negative mutant of this protein. Prion variants with distinct conformations were differentially sensitive to prion inhibition, despite the fact that each of the variants were impacted by the mutant in the same way - a reduction in kinetic stability and an increased sensitivity to fragmentation. The threshold for clearance of the existing aggregates was determined by both the self-replication efficiencies of the variants and also the dosage of the mutant, indicating that changing dosing regimes might be effective for treating prion variants. In addition to dominant-negative mutant inhibition, prion persistence can also be inhibited by heat shock. Our studies indicate that this inhibition requires the activity of the deacetylase Sir2, which promotes asymmetric retention of misfolded proteins after cellular stress. Intriguingly, Sir2 mediates its effects through a mating-type specific gene YJL133C-A, which localizes to the mitochondrial membrane. Together, our studies indicate that prion persistence and clearance arise from a complex interplay between prion protein conformation and sequence and the cellular environment in which they reside.
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Gruber, Claudia. "Investigation into the regulatory mechanism of BRCA2 stability." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:e69ab649-f955-48d2-a7c5-48b65f15df45.
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Inherited mutations in the BRCA2 gene predispose individuals to the development of breast and ovarian cancers. The BRCA2 protein plays a fundamental role in the repair of DNA double strand breaks by homologous recombination (HR). BRCA2 mediates the recruitment of the RAD51 recombinase to DNA damage sites, which in turn promotes homologous pairing and strand exchange during HR. It has been reported that increased BRCA2 mRNA levels correlate with poor cancer prognosis, and recently it has been shown that increased levels of BRCA2 suppress HR. As HR is regulated through the cell cycle and can only be employed during S and G2 phases of the cell cycle, in this study, the cell cycle-dependent regulation of BRCA2, as a key player of HR, was investigated. In this study I report that BRCA2 stability is regulated by the ubiquitin-proteasome system (UPS), which has become increasingly evident as an important regulator of DNA repair. In line with this, I found that BRCA2 can be ubiquitylated in vivo and that it interacts with proteins of the UPS. Interestingly, I observed that BRCA2 levels and its ubiquitylation status change during the cell cycle. Using a siRNA-based approach, I identified a candidate E3 ubiquitin ligase, the SCFFBXW7 complex, which is also a known major cell cycle regulator. siRNA-mediated knockdown of FBXW7 led to stabilization of BRCA2 and overexpression of FBXW7 resulted in BRCA2 ubiquitylation in vivo. Furthermore, I have refined the regions that the SCFFBXW7 interacts with on BRCA2, which likely occurs in a phosphorylation-dependent manner. Taken together, these observations suggest that BRCA2 stability is regulated by the UPS in a cell cycle-dependent manner, which may be an important regulatory mechanism for BRCA2 function.
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Regonini, Domenico. "Anodised TiO2 nanotubes : synthesis, growth mechanism and thermal stability." Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492286.
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Anodised titanium dioxide (titania, TiO2) nanotubes have been widely studied over the last few years, following the discovery in 1999 of nanoporous TiO2 films prepared via anodisation in aqueous solution containing small quantities of hydrofluoric acid. The synthesis of nanotubular titania by anodisation, a relatively simple and low cost technique, represents a motivation for scientists, considering the impact that such a material could have on a variety of applications, including gas-sensing, biomedical, photocatalysis, and photovoltaics. This research project has focused on the optimisation of the growth process of anodic titania nanotubes, both in an aqueous (NaF/Na2SO4) and an organic (Glycerol/NaF) electrolyte containing fluorine ions. Reproducibility and the ability to generate anodic films having a thickness of several micrometers are fundamental steps to be achieved before investigating any possible application of the nanotubes. To characterise the anodic specimens and build upon the general lack of information on the growth mechanism, a comprehensive study of the different stages of the process has been performed, using Scanning and Transmission Electronic Microscopy (SEM and TEM). Among the questions to be addressed in this thesis, is to establish whether the anodic film undergoes a transition from pores to tubes or develops a tubular morphology from the beginning of its growth. Additional characterisation of the anodisation process includes the study of current-time curves, and chemical composition analysis of the anodic layers using X-ray Photo-Electron Spectroscopy (XPS). The thermal stability of the nanotubes and structural/morphological changes as a result of heat treatment at different temperatures were also studied, again using SEM, TEM, XPS and Raman spectroscopy. The final part of the thesis is dedicated to preliminary work on the use of anodised TiO2 nanotubes in Dye Sensitized Solar Cells (DSSCs), along with suggestions for future works and general conclusions.
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Vanteddu, Teja. "Grasp Stability with a Robotic Exoskelton Glove." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/93357.
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Grasp stability was studied and researched upon by various research groups, but mainly focused on robotic grippers by devising conditions for a stable grasp. Maintaining grasp stability is important so as to reduce the chances of the object slipping and dropping. But there was little focus on the grasp stability of robotic exoskeleton gloves and most of the research was focused on mechanical design. A robotic exoskeleton glove was developed as well as novel methods to improve the grasp stability. The exoskeleton glove developed is intended for patients who have suffered paralysis of the hand due to stroke or other factors. The robotic glove aids them in grasping objects as part of daily life activities. The glove is constructed with rigidly coupled 4-bar linkages attached to the finger tips. Each linkage mechanism has 1- Degree of Freedom (DOF) and is actuated by a linear Series Elastic Actuator (SEA). Two methods were developed to satisfy two of the conditions required for a stable grasp. These include deformation prevention of soft objects, and maintaining force and moment equilibrium of the objects being grasped. Simulations were performed to validate the performance of the algorithms. A battery of experiments was performed on the integrated prototype in order to validate the performance of the algorithms developed.Master of Science
An exoskeleton glove is robotic device that can aid people who suffer from paralysis of their hands caused by a stroke or other factors with the primary goal of allowing them to regain the basic ability of grasping objects and thereby improving their quality of life. The exoskeleton glove developed in this research is focused on objects grasping assistance rather than for rehabilitation purposes. Since the exoskeleton glove lacks conscious senses like a human hand typically possesses, it may not be able to apply sufficient grasping force or may apply excessive force than required irrespective of the object being grasped. In order to ensure that the exoskeleton glove applies the proper amount of force, two novel methods were developed which help improve the overall grasping performance of the robotic glove. These methods use sensors that enable the glove to react to the force interaction changes that exists between the hand and the object being grasped through the exoskeleton glove. The first method detects any deformation that may occur while grasping a soft object and applies lesser force accordingly to prevent further damage to the object. The second method uses motion sensor to detect any movement by the user while grasping the object and applies corrective forces so that the object doesn’t slip from the hand. A prototype was designed and integrated and the two methods were tested on the prototype to validate them.
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Jones, Christopher Buchan. "The hydrolysis of cirazoline and the mechanism of stabilization by SDDS." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380945.
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Zhao, Tinghe. "Morphological stability and surface growth mechanism studies in electrocrystallization of copper." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0004/MQ43242.pdf.
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Joshi, Manish D. "Electrostatic interactions and the pH-dependent stability and mechanism of BCX." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61124.pdf.
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Karlström, Mikael. "Structure determination, thermal stability and catalytic mechanism of hyperthermostable isocitrate dehydrogenases /." Stockholm, 2006. http://diss.kib.ki.se/2006/91-7140-778-2/.
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Chen, Wei 1969. "The mechanism of Cbp1 protein-dependent COBmRNA stability in yeast mitochondria." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/288848.
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It has been one hundred years since mitochondria were first observed and recorded by Altman in 1890, when they were named bioblasts. Ten years later, "mitochondrion", which means threadlike granule, started to be used. It is still an unanswered question where this organelle originated. More and more evidence and enthusiasm favor the hypothesis that mitochondria have evolved from engulfed prokaryotic symbionts (Martin and Muller, 1998). An opposing idea proposed that mitochondria just represent another kind of intracellular membrane system, like Golgi (Cavalier-Smith, 1987). Whichever is true, it is known today that mitochondria are well-defined and ubiquitous cellular structures compartmentalized by double membranes. They not only provide some of their own genetic information, but also are the site of cellular lipid synthesis and oxidative phosphorylation. Since mitochondria are such complex functional units, the study of mitochondrial biogenesis (a process to produce a respiratory competent organelle) is a combined issue of genetics, biochemistry and chemistry. It aims to answer questions regarding mitochondrial morphology, continuity, protein and phospholipid syntheses, protein transport, etc. This study is concentrated on a since regulatory step of a single mitochondrial gene in yeast, i.e. the stabilization of the cytochrome b (COB) mRNA, which requires the nuclear-encoded Cbp1 protein. The results of my study support that the nuclear-encoded Cbp1 protein stabilizes COB messages in two different ways: First, it processes the 5'-untranslated region (UTR); second, it is required after formation of the mature 5'-end of COB mRNA. Evidence is provided that Cbp1 physically interacts with a CCG element in the COB 5'-UTR, and the maintenance of this interaction is critical for COB mRNA accumulation. Suppressor analysis of COB 5'-UTR mutations identified factors in general mitochondrial mRNA turnover pathways. Thus, in addition to studying the mechanism of Cbp1-dependent COB mRNA stabilization, the further analysis of genes identified by mutation in this work may reveal previously uncharacterized components in the general pathways of yeast mitochondrial mRNA decay.
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Holuša, David. "Návrh stabilizačního mechanismu pro FPV kamery s využitím CAD/CAM systémů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231463.
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This diploma thesis provides a comprehensive proposal of stabilization mechanism for sensing and FPV camera for remote controlled propeller plane. Summarizes the current human knowledge milestones in the field and describes the current state of knowledge and the market situation. Taking into account all acquired knowledge the author then describes two different design proposals outlining its related processes, such as manufacturing, electronics installation and commissioning.
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Avila, Alex. "Origami-Based Design of Fold States and Stability." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7036.
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Origami is a potentially elegant and powerful source of inspiration for many engineering designs. The viable shapes (fold states) of a single device allow it to perform multiple, seemingly contradictory, functions. The fold state is a large factor in the device's performance, but there are challenges in selecting and maintaining those fold states. In this thesis we analyze existing concepts for overcoming these challenges. Those concepts are compared with those that occur in origami-based devices. From this analysis fundamental gaps were identified, specifically, shortcoming in the terminology used to refer to (1) non-flat origami states and (2) sets of facets and creases. Likewise we found a need for a comprehensive categorization method of fold states. Fold states are divided into seven types based on the set of fold angles they contain: U, P, F, UP, UF, PF, and UPF. The origami-based devices are analyzed based on their functional fold states, showing an emphasis on P and PF fold states. The fold states and their functions are tabulated. We demonstrate the table as a tool in an origami-based design method. Selecting fold states for an application is just the first step for effective use of origami. Once selected, the origami fold state must be maintained during use to perform its functions. This thesis also outlines the Origami Stability Integration Method (OSIM) for integrating a wealth of stability techniques. These techniques are categorized and analyzed to assist designers in selecting a technique for a device's application. Both methods, the fold-state selection method and the OSIM, are demonstrated in designing an origami-based ballistic barrier. The barrier is designed to stow in a compact fold state and deploy to a partially folded state to provide protection during armed conflicts. Quick deployment and a stable structure make the barrier a valuable example of origami-based design, demonstrating these two methods in addressing some of origami's design challenges.
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Li, Yuan. "IL10 mRNA stability defects as a mechanism contributing to the development of lupus." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439310501.
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Hejduk, Oldřich. "Hodnocení statistického řízení jakosti (SPC) pro řešení stability procesů u tlakově litých odlitků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230933.
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The aim of the theoretical part of this thesis is to describe the system of the aluminium casting alloys, with focus on the aluminium castings used for die casting. In this part of the thesis the different methods of the quality management are described. The practical application of these methods is described in the experimental part of this thesis, in which we focus on the evaluation of the statistical quality management and the process stability of the die casting parts of the selector mechanism cover. This part of the thesis also contains suggestion for the QFD method for this cast.
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Karasek, Matej. "Robotic hummingbird: design of a control mechanism for a hovering flapping wing micro air vehicle." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209177.
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The use of drones, also called unmanned aerial vehicles (UAVs), is increasing every day. These aircraft are piloted either remotely by a human pilot or completely autonomously by an on-board computer. UAVs are typically equipped with a video camera providing a live video feed to the operator. While they were originally developed mainly for military purposes, many civil applications start to emerge as they become more affordable.
Micro air vehicles are a subgroup of UAVs with a size and weight limitation; many are designed also for indoor use. Designs with rotary wings are generally preferred over fixed wings as they can take off vertically and operate at low speeds or even hover. At small scales, designs with flapping wings are being explored to try to mimic the exceptional flight capabilities of birds and insects.
The objective of this thesis is to develop a control mechanism for a robotic hummingbird, a bio-inspired tail-less hovering flapping wing MAV. The mechanism should generate moments necessary for flight stabilization and steering by an independent control of flapping motion of each wing.
The theoretical part of this work uses a quasi-steady modelling approach to approximate the flapping wing aerodynamics. The model is linearised and further reduced to study the flight stability near hovering, identify the wing motion parameters suitable for control and finally design a flight controller. Validity of this approach is demonstrated by simulations with the original, non-linear mathematical model.
A robotic hummingbird prototype is developed in the second, practical part. Details are given on the flapping linkage mechanism and wing design, together with tests performed on a custom built force balance and with a high speed camera. Finally, two possible control mechanisms are proposed: the first one is based on wing twist modulation via wing root bars flexing; the second modulates the flapping amplitude and offset via flapping mechanism joint displacements. The performance of the control mechanism prototypes is demonstrated experimentally.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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PETROVIC, Mario. "Wrinkle generation mechanism in flat and cylindrical membranes undergoing shear deformation." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199271.
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Nguyen, Tan. "Load transfer mechanisms and seismic stability of embankments subjected to basal subsidence." Kyoto University, 2018. http://hdl.handle.net/2433/235077.
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Greenwood, Jacob Ryan. "Enabling Compact Devices Through Origami and Developable Mechanisms." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7764.
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This thesis provides resources that enable the design of novel and compact mechanical devices by providing terminology, engineering models, and design methods in the fields of developable mechanisms and origami-based engineering.The first part of this work presents engineering models to aid in the design of cylindrical developable mechanisms. These models take into account the added spatial restrictions imposed by the developable surface. Equations are provided for the kinematic analysis of cylindrical developable mechanisms. A new classification for developable mechanisms is also presented (intramobile, extramobile, and transmobile) and two graphical methods are provided for determining this classification for single-DOF planar cylindrical developable mechanisms. Characteristics specific to four-bar cylindrical developable mechanisms are also discussed. The second part addresses a key challenge in origami design: how to achieve stability while maintaining the desired folding motion. The origami stability integration method (OSIM) provides an approach for graphically combining various techniques to achieve stability. This thesis presents improvements and additions to the OSIM that allow it to be applied to many different scenarios. Existing stability techniques are also categorized into four groups based on whether they are intrinsic or extrinsic to the origami pattern and whether they exhibit gradual or non-gradual energy storage behaviors. These categorizations can help designers select appropriate techniques for their application. Four case studies are presented which use the OSIM and the technique categorization to conceptualize stability in origami-based devices.
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Lee, Kwang Jik. "Study of stability of ZnO nanoparticles and growth mechanisms of colloidal ZnO nanorods." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4303.
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After hydrolyzing zinc acetate in methanol solution, spherical ZnO nanoparticles in the
size range from about 2.5 to 5 nm were synthesized by maintaining a ZnO concentration
of 0.02M. Compared to ZnO nanoparticles prepared via other methods, the particles
prepared using our novel colloidal chemistry exhibit narrow size distribution and a high
sensitivity to the surrounding environment. The structure and composition of the white
powders precipitated from the colloidal solution can vary, depending on how the powder
samples are prepared. Factors such as desorption and adsorption of methanol, binding of
water and exposure to humid air have been studied to correlate to the structure and
composition observed from the precipitated powder. Methanol desorption rate and
excess KOH on the particle surface have played an important role in the structural
changes. Furthermore, upon annealing, the white precipitate is recovered to wurtize ZnO.
XRD and TEM are used to study the structural transformation of ZnO nanoparticles.
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Munyengwa, Tebogo. "Monetary policy transmission mechanism in Botswana: how does the Central Bank policy rate affect the economy?" University of the Western Cape, 2012. http://hdl.handle.net/11394/4587.
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Magister Economicae - MEconThe transmission mechanism of monetary policy has generated a substantial amount of interest in economic research in many countries, with most studies focusing on how a change in monetary policy stance, usually defined as an exogenous shock in a short-term interest rate, affects the economy at a national level, with changes in output, inflation and exchange rates being the key variables under investigation. This study adopts a similar analysis, with the general objective of examining the effectiveness of monetary policy in Botswana. Specifically, this study aims at finding out how the central bank rate affects inflation in Botswana and the duration of its effects on economic variables in Botswana. The study adopts the recursive VAR methodology, using quarterly data from 1995 quarter one to 2009 quarter four. The results show that monetary policy is most effective via the interest rate channel in Botswana, followed by the credit channel and then the exchange rate channel. In addition, the results reflect that the economy reacts to monetary policy actions with a one period lag, with the effect lasting for seven quarters.
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Pais, Joana. "Incentives in Random Matching Markets." Doctoral thesis, Universitat Autònoma de Barcelona, 2005. http://hdl.handle.net/10803/4062.
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El objetivo de esta tesis es estudiar el funcionamiento de los mercados de trabajo dónde los trabajadores son asignados a las empresas por procesos aleatorios usando modelos de asignación bilateral. En estos modelos, los agentes pertenecen a uno de dos conjuntos disjuntos -empresas y trabajadores- y cada agente tiene preferencias ordinales sobre el otro lado del mercado. El problema se reduce a una asignación de los miembros de estos dos conjuntos el uno al otro.En el segundo capítulo, titulado "On Random Matching Markets: Properties and Equilibria," se describe un algoritmo que empieza desde una asignación cualquiera y continua creando, a cada paso, una asignación provisional. En cada momento del tiempo, una empresa es elegida al azar y se considera el mejor trabajador en su lista de preferencias. Si este trabajador ya está asignado a una empresa mejor, la asignación no se altera. En caso contrario, el trabajador y la empresa quedan temporalmente juntos hasta que el trabajador reciba una propuesta de trabajo mejor. Seguidamente, se exploran algunas propiedades del algoritmo; por ejemplo, el algoritmo generaliza el famoso algoritmo de "deferred-acceptance" de Gale y Shapley. Luego se analizan los incentivos que los agentes enfrentan en el juego de revelación inducido por el algoritmo. El hecho de que las empresas son seleccionadas al azar introduce incertidumbre en el resultado final. Una vez que las preferencias de los agentes son ordinales, se utiliza un concepto de equilibrio ordinal, basado en la dominancia estocastica de primer orden.
En el tercer capítulo, "Incentives in Decentralized Random Matching Markets," se considera un juego secuencial dónde los agentes actúan de acuerdo con las reglas generales del algoritmo. En este capítulo, las estrategias de los agentes pueden tomar una forma cualquiera y no tienen que coincidir con una lista de preferencias. El primer jugador es la Naturaleza, que elige una secuencia de empresas , que representa la incertidumbre existente en un mercado descentralizado. Luego, las empresas son elegidas de acuerdo con la sequencia y les es dada la oportunidad de hacer una propuesta. Ya que el juego es dinamico, se analizan los equilibrios de Nash ordinales perfectos en subjuegos.
En "Random Stable Mechanisms in the College Admissions Problem," se considera el juego inducido por un mecanismo aleatorio estable. En este capítulo, se caracterizan los equilibrios de Nash ordinales. En particular, puede obtenerse una asignación en un equilibrio dónde las empresas revelan sus verdaderas preferencias si y sólo si la asignación es estable con respecto a las verdaderas preferencias.
Por fin, en el último capítulo, se caracterizan los equilibrios perfectos ordinales en el juego inducido por un mecanismo aleatorio estable.
The purpose of this thesis is to explore the functioning of labor markets where workers are assigned to firms by means of random processes using two-sided matching models. In these models, agents belong to one of two disjoint sets -firms and workers- and each agent has ordinal preferences over the other side of the market. Matching reduces to assigning the members of these two sets to one another.
In the second chapter, entitled "On Random Matching Markets: Properties and Equilibria," I describe an algorithm that starts with any matching situation and proceeds by creating, at each step, a provisional matching. At each moment in time, a firm is randomly chosen and the best worker on its list of preferences is considered. If this worker is already holding a firm he prefers, the matching goes unchanged. Otherwise, they are (temporarily) matched, pending the possible draw of even better firms willing to match this worker. Some features of this algorithm are explored; namely, it encompasses other algorithms in the literature, as Gale and Shapley's famous deferred-acceptance algorithm. I then analyze the incentives facing agents in the revelation game induced by the proposed algorithm. The random order in which firms are selected when the algorithm is run introduces some uncertainty in the output reached. Since agents' preferences are ordinal in nature, I use ordinal Nash equilibria, based on first-order stochastic dominance.
In the third chapter, "Incentives in Decentralized Random Matching Markets," I take a step further by considering a sequential game where agents act according to the general rules of the algorithm. The original feature is that available strategies exhaust all possible forms of behavior: agents act in what they perceive to be their own best interest throughout the game, not necessarily according to a list of possible matches. The game starts with a move by Nature that determines the order of play, reflecting the inherently uncertain features of a decentralized market. Then, firms are selected according to the drawn order and given the opportunity to offer their positions. In order to account for the dynamic nature of the game, I characterize subgame perfect ordinal Nash equilibria.
Following a different approach, in "Random Stable Mechanisms in the College Admissions Problem," I consider the game induced by a random stable matching mechanism. In this paper, I characterize ordinal Nash equilibria, providing simultaneously some results that extend to deterministic mechanisms. In particular, a matching can be obtained as the outcome of a play of the game where firms reveal their true preferences if and only if it is stable with respect to the true preferences.
In closing, in the last chapter I characterize perfect equilibria in the game induced by a random stable mechanism.
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Barreau, Matthieu. "Stability analysis of coupled ordinary differential systems with a string equation : application to a drilling mechanism." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30058.
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Cette thèse porte sur l'analyse de stabilité de couplage entre deux systèmes, l'un de dimension finie et l'autre infinie. Ce type de systèmes apparait en physique car il est intimement lié aux modèles de structures. L'analyse générique de tels systèmes est complexe à cause des natures très différentes de chacun des sous-systèmes. Ici, l'analyse est conduite en utilisant deux méthodologies. Tout d'abord, la séparation quadratique est utilisée pour traiter le côté fréquentiel de ce système couplé. L'autre méthode est basée sur la théorie de Lyapunov pour prouver la stabilité asymptotique de l'interconnexion. Tous ces résultats sont obtenus en utilisant la méthode de projection de l'état de dimension infinie sur une base polynomiale. Il est alors possible de prendre en compte le couplage entre les deux systèmes et ainsi d'obtenir des tests numériques fiables, rapides et peu conservatifs. De plus, une hiérarchie de conditions est établie dans le cas de Lyapunov. L'application au cas concret du forage pétrolier est proposée pour illustrer l'efficacité de la méthode et les nouvelles perspectives qu'elle offre. Par exemple, en utilisant la notion de stabilité pratique, nous avons montré qu'une tige de forage controlée à l'aide d'un PI est sujette à un cycle limite et qu'il est possible d'estimer son amplitudeThis thesis is about the stability analysis of a coupled finite dimensional system and an infinite dimensional one. This kind of systems emerges in the physics since it is related to the modeling of structures for instance. The generic analysis of such systems is complex, mainly because of their different nature. Here, the analysis is conducted using different methodologies. First, the recent Quadratic Separation framework is used to deal with the frequency aspect of such systems. Then, a second result is derived using a Lyapunov-based argument. All the results are obtained considering the projections of the infinite dimensional state on a basis of polynomials. It is then possible to take into account the coupling between the two systems. That results in tractable and reliable numerical tests with a moderate conservatism. Moreover, a hierarchy on the stability conditions is shown in the Lyapunov case. The real application to a drilling mechanism is proposed to illustrate the efficiency of the method and it opens new perspectives. For instance, using the notion of practical stability, we show that a PI-controlled drillstring is subject to a limit cycle and that it is possible to estimate its amplitude
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Zhang, Xiaofeng. "Structural studies of lumazine synthases - thermostability, catalytic mechanism and molecular assembly /." Stockholm, 2005. http://diss.kib.ki.se/2006/91-7140-605-0/.
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Höing, Oliver [Verfasser], Wolfgang [Akademischer Betreuer] Wessels, and Christine [Akademischer Betreuer] Neuhold. "Asymmetric Influence: National Parliaments in the European Stability Mechanism / Oliver Höing. Gutachter: Wolfgang Wessels ; Christine Neuhold." Köln : Universitäts- und Stadtbibliothek Köln, 2015. http://d-nb.info/1080719229/34.
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Ishino, So. "Physicochemical studies on reaction mechanism of molecular chaperone GroE." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199490.
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Kganetsano, Tshokologo A. "The transmission mechanism of monetary policy in Botswana." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/7988.
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Macroeconomic stability is one of the most important national objectives in any country. However, economies are often subjected to a number of shocks (internal and external), which can be destabilising, produce volatility and make it difficult to achieve and maintain economic stability. Consequently, various policies are used to help deal with the various shocks that may affect the economy. Of all the available policies, monetary policy appears to have been ever more at the centre of macroeconomic policymaking. Meanwhile, for monetary policy to be effective, there is a need for a better understanding of the transmission mechanism, i.e., the process through which monetary policy decisions are transmitted into changes in real output and inflation. Whereas extensive research on the transmission mechanism has been conducted in developed countries, such work in developing countries, especially in Africa is lacking. This could be due to the fact that it was not long time ago, around the 1990s that countries in Africa started adopting the more modem central bank operations in a market-based economic and financial system characterised by indirect monetary policy. Such operations require an understanding of the transmission mechanism. Lack of empirical analysis of the monetary transmission mechanism in Botswana and developing countries of Africa in general, is the main motivating factor behind this thesis. The main objective of this thesis is, therefore, to estimate the transmission mechanism of monetary policy in Botswana. Three different, but complementary techniques (the Narrative Approach, Vector Autoregression (VAR) analysis and the Structural Approach involving the estimation of a small structural model for Botswana economy) are used. Results from these methods tell a consistent story and indicate that monetary policy in Botswana affects real output and inflation through the interest rate channel, while the exchange rate channel is not operational. The credit channel is also active but not strong. The structural approach also indicates that devaluation is contractionary in Botswana, but more research is necessary before firmer conclusions could be made.
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Carrington, James Michael. "Vacuum stability of the standard model and BSM extensions." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8851.
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The Standard Model scalar potential contains a minimum at the Electroweak scale, responsible for the masses of the weak gauge bosons through the Higgs mechanism. However, if the Electroweak minimum is only a local minimum, and there exists a global minimum at a higher energy in the Higgs potential, then in a su ciently old universe we would expect the vacuum expectation value to be at the global minimum. The absence of a global minimum at higher energy is related to the condition that the Higgs self coupling is greater than or equal to zero for all energies. For any model that fails this, we expect new physics to enter before the energy at which the coupling becomes negative. We developed tools to automate the derivation of beta functions for renormalisable gauge theories, and used these to carry out evolution of the renormalisation group equations for the Standard Model and three extensions to the Standard Model | the Standard Model with a fourth generation, the Standard Model with right-handed neutrinos and a Left-Right Symmetric Model. We conclude that of these four models, the Standard Model is the only one in which all the couplings remain perturbative, and in which the Electroweak minimum is a global minimum.
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Qi, Xianghong. "Influence of Cooperativity on the Protein Folding Mechanism." Kent State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=kent1219247325.
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Fu, Yao-Tsung. "Molecular Simulation of Dipsersion and Mechanical Stability of Organically Modified Layered Silicates in Polymer Matrices." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1296182515.
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Brdečková, Helena. "Sesuvy v mělkých neogenních pánvích při jihozápadním okraji karpatské předhlubně na Moravě." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392315.
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The Carpathian foredeep is a lengthwise depressed area in the Carpathian foreland. In Moravia, it is mainly filled with Neogene soils. The thesis focuses on the South Moravian landslides which occurred in shallow relicts of Neogene deposits along a foredeep margin which lie on the rocks of the Bohemian Massif. Landslide activity within these shallow basins is a result of a number of factors. In the theoretical part, important general features of landslide areas, their geological conditions and hydrogeological regime are investigated. Next, available data on the geomechanical behaviour of soils, often connected with these landslides, are summarized and evaluated. The case studies deal with the landslide localities Budkovice-Svízla, Brno-Bystrc and Znojmo. The case study of Budkovice-Svízla is based on an extensive engineering geological survey of the locality and the measurement of groundwater levels in the years 1988 – 2017. In the thesis, the hydrogeological regime of the area is analysed and a reconstruction of the ground surface before slope movement is carried out. The probable trigger mechanisms, the development of sliding and the efficiency of the executed remedies of the landslide are evaluated by numerical studies. In conclusion, general recommendations for an engineering-geological survey and building activities in the area of interest are formulated.
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Marutani, Kyohei. "Essays on the Theory of Indivisible Good Markets." Kyoto University, 2020. http://hdl.handle.net/2433/253062.
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Zizka, Zdenek [Verfasser]. "Stability of slurry supported tunnel face considering the transient support mechanism during excavation in non-cohesive soil / Zdenek Zizka." Düren : Shaker, 2019. http://d-nb.info/1200808436/34.
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Xiao, Neng. "Investigating Growth Mechanism of Potassium Superoxide in K-O2 Batteries and Improvements of Performance and Anode Stability upon Cycling." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1462890425.
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Oztekin, Burak. "Assessment Of Degradation Mechanism And Stability Of A Cut Slope In Jointed And Sheared Limestone Along Ankara-eskisehir E90 Highway." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605631/index.pdf.
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Due to rapidly growing population of Ankara city (Turkey) and traffic load, it is required to widen some of the existing highways. One of them is Ankara-EskiSehir (E-90) highway that connects highly populated areas to the city center. During widening, several cut slopes were formed along the
highway route. However, some instability problems such as small-sized rock falls and rock detachments have occurred along a cut slope in highly jointed, folded and sheared limestone. They caused local degradation of the cut slope. The cut slope has a slope angle varying from 71°to 84°
and contains several shear zones. In this study, the relationships between the existing detachment zones and various parameters (e.g. block size, point load strength index, weathering, shear zone, daylight zone) considered to be important for slope instability were investigated using GIS-based statistical landslide susceptibility analyses in order to predict the further aerial extension of the detachment zones with time. During the overlay analyses, statistical index and weighting factor methods were used by means of TNT-MIPS software. The outcomes of the analyses using both methods are compared and evaluated together with the field observations to check the reliability of the methods and to assess the detachment zones that may develop in the future. Additionally, limit equilibrium analyses were also carried out for the determination of the possible large scale mass failures. The overlay analyses indicate some risky zones where detachments are likely to occur in the future. On the other hand, the limit equilibrium analysis of the rock mass using Bishop simplified method shows that except one section no mass failure is expected in the cut slope. Suitable remediation measures which include the use of wire mesh, shotcrete, toe support, and concrete barrier blocks or catch/barrier fences are recommended for these zones.
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Hashida, Yasuhiko. "Kinetic and thermodynamic studies on regulatory mechanism of the activity and stability of thermolysin by divalent cations, sugars, and phosphoramidon." Kyoto University, 2007. http://hdl.handle.net/2433/136572.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第13449号
農博第1660号
新制||農||949(附属図書館)
学位論文||H19||N4305(農学部図書室)
UT51-2007-S480
京都大学大学院農学研究科食品生物科学専攻
(主査)教授 井上 國世, 教授 加納 健司, 教授 安達 修二
学位規則第4条第1項該当
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Ballard, Andrew. "Kinetics and mechanism of H D exchange reactions and racemisation in aqueous solutions : configurational stability of ester and amide arylglycine derivatives." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/55130/.
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The configurational stability of a range of stereogenic centres in aqueous media has been studied, with the goal of understanding the structural and environmental factors contributing to configurational instability. This information will be of use to the pharmaceutical industry, for which the chiral integrity of drug compounds is imperative. Chapter 1 outlines the background to this project, providing an overview of pharmacological racemisation including potential mechanisms, examples from literature, and the methodology used. Chapter 2 focuses on database mining studies undertaken on AstraZeneca compound libraries, the results of which guided the structures investigated in the rest of the thesis. Most compounds in the libraries do not appear at risk of racemisation. Of those that do, stereogenic centres with proton, carbonyl, aromatic and nitrogen substituents appear most frequently. Chapter 3 discusses experimental work determining rate constants of proton-deuterium exchange (as a model for racemisation) under physiological conditions, for a set of TV-acetyl arylglycine methyl esters. These rate constants suggest that such compounds are susceptible to in vivo racemisation through an SeI mechanism. Chapter 4 outlines experimental work determining rate constants of proton-deuterium exchange, for a set of N-substituted phenylglycine amides. These compounds undergo H/D exchange through an SeI mechanism, although the rate at which H/D exchange occurs suggests they would not be at risk of in vivo racemisation. These results show that an amide substituent is far weaker than a methyl ester in facilitating racemisation. Chapter 5 reports the results of computational studies performed on the compounds investigated in Chapters 3 and 4. The energy gap between a molecule and its anion when deprotonated at the stereogenic centre was correlated with the experimentally determined data, suggesting that prediction of configurational instability for novel compounds may be possible. This correlation only holds when the PCM solvent model is used in calculations.
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Davis, Shelby Taylor. "The Effects of Synergistic Hydrogen Bonding and Pi-Pi Interactions on the Cycle Stability and Charge Storage Mechanism of Organic Electrode Materials." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1605683661067324.
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Huang, Yan. "Micro- and Nanogel Formation through the Ionic Crosslinking of Polyelectrolytes." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1417781855.
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Mebrahtu, Tesfay Kiros [Verfasser], Stefan [Gutachter] Wohnlich, and Michael [Gutachter] Alber. "Failure mechanism and stability analysis of deep-seated landslides in the northwestern Rift escarpment, Ethiopia / Tesfay Kiros Mebrahtu ; Gutachter: Stefan Wohnlich, Michael Alber ; Fakultät für Geowissenschaften." Bochum : Ruhr-Universität Bochum, 2021. http://d-nb.info/1233484192/34.
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Roussarie, Elodie. "Identification et caractérisation de bilirubines oxydases pour l'élaboration de biopiles enzymatique à glucose/oxygène." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0161/document.
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La puissance de la biopile enzymatique à glucose/oxygène est limitée par sa partiecathodique. Afin de contourner cette limitation, nous avons étudié les enzymescathodiques : les Bilirubine oxydases (BODs). Dans le but de mieux appréhender ces BODs, lemécanisme réactionnel, la nature de l’étape limitante et l’effet des sels ont alors été étudiés.Deux mécanismes différents sont retrouvés en fonction du mode de transfert des protons etdes électrons (4 fois 1H+/1e- ou 2 fois 2H+/2e-). De plus, nous avons démontré que l’étapelimitante est l’oxydation du substrat pour les trois substrats testés et que les sels agissent auniveau du cuivre T1. Les principales limitations des BODs sont leur stabilité à 37 °C ainsi queleur inhibition par le NaCl. Deux techniques ont alors été utilisées pour identifier des BODsplus résistantes. La première méthode est l’extraction de nouvelles enzymes à partird’organismes extremophiles. Elle a permis d’isoler la BOD d’Anaerophaga thermohalophilaqui possède une bonne résistance au NaCl mais une densité de courant faible. Dans unsecond temps, afin de reconstruire des séquences ancestrales, la phylogénie de la familledes Bacillus Bacterium a été effectuée. Cette technique a permis l’identification de troisBODs possédant des caractéristiques très intéressantes : la BOD de Bacillus nakamurai etdeux BODs ancestrales (Noeud 10 et Noeud 13). Par exemple, après une heure à 37°C et 140mM de NaCl, le Noeud 10 possède une meilleure densité de courant que la BOD de Bacilluspumilus, qui est l’enzyme utilisée comme base de la phylogénie. La seconde technique estdonc une méthode de choix permettant la découverte de nouvelles enzymes à la fois plusstables et plus résistantes que les enzymes actuelles. Elle ouvre de grandes perspectivespour l’utilisation des BODs comme enzymes cathodiques ou pour d’autres applicationsbiotechnologiques. Enfin, nous avons montré que l’immobilisation de la BOD de B. pumilusdans le matériau Si-(HIPE) permet la décoloration cyclique de colorants chimiques surplusieurs moisPower of glucose/oxygen enzymatic biofuel cell is limited by the cathodic part. In order to prevent this limitation, we studied cathodic enzymes: Bilirubin oxidases (BODs). For this purpose, the kinetic mechanism, rate-limiting step and salts effect were determined. Two different mechanisms are observed depending on the electron/proton transfer (4 times1H+/1e- or 2 times 2H+/2e-). We also demonstrated that the rate-limiting step is the substrate oxidation for the three substrates tested and salts act around the T1 copper. Main BODs limitations are their stability at 37°C and their inhibition by NaCl. Two methods were used toidentify the most resistant BODs. The first one was the identification of new enzymes from extremophile organisms. It allows to isolate BOD from Anaerophaga thermohalophila whichhas good NaCl resistance but low current density. In addition, in order to reconstructancestral sequences, phylogeny of Bacillus Bacterium family was performed. This methodidentified three BODs with interesting features: BOD from Bacillus nakamurai and twoancestral BODs (Noeud 10 and Noeud 13). For example, after one hour at 37°C and 140 mMNaCl, Noeud 10 has a better current density than the BOD from Bacillus pumilus, which is theenzyme used as basis for the phylogeny. This second method allowed the discovery of newenzymes that were both more stable and more resistant than actual enzymes. Thistechnique opens up valuable prospects for the use of BODs as cathodic enzymes or for otherbiotechnological applications. In the end, we demonstrated that BOD from B. pumilusimmobilization in Si-(HIPE) materials allows cyclic discoloration of chemical dyes duringseveral months
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Bauer, Stefanie [Verfasser], and Armin [Akademischer Betreuer] Buschauer. "Quinoline carboxamides as modulators of Breast Cancer Resistance Protein (ABCG2): Investigations on potency, selectivity, mechanism of action, cytotoxicity, stability and drug-like properties / Stefanie Bauer. Betreuer: Armin Buschauer." Regensburg : Universitätsbibliothek Regensburg, 2014. http://d-nb.info/1048729540/34.
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Zizka, Zdenek [Verfasser], Markus [Gutachter] Thewes, and Adam [Gutachter] Bezuijen. "Stability of slurry supported tunnel face considering the transient support mechanism during excavation in non-cohesive soil / Zdenek Zizka ; Gutachter: Markus Thewes, Adam Bezuijen ; Fakultät für Bau- und Umweltingenieurwissenschaften." Bochum : Ruhr-Universität Bochum, 2019. http://d-nb.info/1191481689/34.
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Ferreira, de Morais Rodrigo. "Study of the stability and the reactivity of Pt and Pt3Ni model catalyst for PEM fuel cells : an ab-initio based multiscale modeling approach." Thesis, Lyon, École normale supérieure, 2011. http://www.theses.fr/2011ENSL0694.
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Les piles à combustible à membrane électrolyte polymère (PEMFC) sont considérées depuis de nombreuses années comme une solution intéressante pour remplacer les moteurs thermiques. Cependant le coˆut élevé du catalyseur et sa faible stabilité limitent la viabilité économique des piles. Le platine pur déposé sur carbone est le catalyseur couramment plus utilisé à la cathode, cependant les nanoparticules d’alliages de type Pt-M (M = Co, Ni ou Fe) sont reconnues depuis peu comme une alternative remarquable en raison d’une meilleure activité et d’une plus grande stabilité au cours de la réaction de réduction de l’oxygène (ORR). Jusqu’à présent, les raisons fondamentales de cette amélioration significative n’ont pas été élucidées d’un point de vue cinétique et théorique. Par ailleurs, la simulation de la performance d’une pile PEM basée sur la loi empirique de Butler-Volmer ne permet pas de prédire de manière correcte ses propriétés cinétiques.Dans cette thèse, nous présentons une méthodologie théorique multi-échelles permettant de simuler le comportement transitoire d’une pile PEM par un modèle cinétique élémentaire. A l’échelle atomique, la théorie de la fonctionnelle de ladensité (DFT) a été utilisée pour modéliser et comprendre la formation de l’eau et du peroxyde d’hydrogène sur trois surfaces différentes de Pt3Ni(111) en comparaison avec la surface de référence Pt(111). Les calculs DFT ont montré que le taux de recouvrement des espèces hydroxyles en surface du catalyseur Pt(111) peut modifier le mécanisme réactionnel et que la plus grande activité catalytique des surfaces d’alliages Pt3Ni(111) est expliquée par la composition chimique en de surface, l’arrangement structural et le rˆole du second métal Ni sur les propri étés électroniques. Les énergies d’activation et les constantes de vitesse des étapes élémentaires du mécanisme réactionnel ont été déterminées et ont ensuite étéutilisées dans un modèle champ moyen décrivant le comportement du champ électrique et la distribution de charge à l’échelle nanométrique. Ces données ont été couplées avec des modèles décrivant la charge au niveau microscopique et les phénomènes de transport des réactifs jusqu’à la cathode. L’influence du choix du mécanisme élémentaire de l’ORR sur les prédictions des courbes de polarisation courant-tension a été déterminée et une comparaison avec les données expérimentales a été proposée pour valider le modèlePolymer Electrolyte Membrane Fuel Cell (PEMFC) is a possible solution for replacing the actual combustion engines. However the cost of the catalyst and its actual low stability are restricting their economical viability. Pt/C is the state-of-the-art cathode catalyst but Pt-M (M = Co, Ni or Fe) alloyed nanoparticles have been proposed as cheap, more stable and powerful, regarding the ORR activity, alternative material. Up to now the fundamental reasons of such improvement have not been elucidated from a kinetic point of view. In the other hand the standard simulation approaches of the PEMFC performance based on Butler-Volmer equations thus not describe correctly the kinetics of such systems. In this thesis we present a multiscale theoretical methodology to scale up ab initio calculated data into elementary kinetic model to simulate PEMFC transient behavior. Density Functional Theory calculations are carried out to understand the catalytic properties of three different Pt3Ni(111) alloy surfaces in comparison with Pt(111). As a result we show that the coverage of OH species may reverse the dominant ORR mechanism on pure Pt catalyst and that the reasons for higher ORR catalytic activity of the Pt3Ni alloys are related to the nature of the second metal, to its surface ability to be less oxidize and to an optimal structural arrangements. Using these properties we have built an elementary kinetic model and calculate the associated constant rate parameters. Then these parameters are implemented into a mean field interfacial model describing the behavior of the electric field and charge distribution at the nanoscale, which is in turn coupled with microscale and mesoscale level models describing the charge and reactants transport phenomena across the cathode. The impact of different ORR mechanisms on the calculated i-V curves is investigated, in comparison with experimental data
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Lin, Fu-Sheng, and 林福生. "Stability of Rhombus Mechanism Damper System." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/43847211791704533376.
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碩士國立成功大學
土木工程學系碩博士班
93
Common building structures provide enough stiffness to reduce its relative displacements between floors. While using the fluid damper as an energy-dissipating devices, it is necessary to magnify the displacement of damper to increase aseismatic energy-dissipating functions. Deh-Shiu Hsu and his colleagues propose the idea of rhombus mechanism damper system, in the hope to increase the damper displacement to dissipate energy because of the nature of rhombus deformation. By means of numerical analysis with SAP2000 software package, it is confirmed that the rhombus mechanism damper system can effectively magnify the displacements, and thus reach the goal of energy dissipation and seismic responses. However, common designs used to simulate this system show the phenomenon of unstable. Such a problem occurs because this system is geographically unstable of three-hinge’s reaction in one point, and it can’t conquer the vertical lateral force. On account of this problem, the purpose of this study is to develop a proper method of simulation under real situations. Looking for the critical of out of plane in rhombus mechanism damper system, the researcher intends to show the feasibility of such a system under actual, high quality working conditions.
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Hsu, Fu Jay, and 許復傑. "Regulatory mechanism of PLK gene family mRNA stability." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/51640292428504859812.
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碩士長庚大學
生物醫學研究所
97
Stability of messenger RNA(mRNA) is very important to control the steady state level of gene expression. Modulation of mRNA stability regulates gene expression level. We want to invest RNA stability by genome-wide analysis by microarray.Microarray data shows Plk families have relative unstable mRNA stability.Many mechanisms change mRNA stability. However, almost 10% of mammalian mRNAs contain adenine and uridine residues known as AU-rich element (ARE) , it can affect mRNA stability. We analyze Plk families 3’UTR and identify ARE motif in Plk3. We also find miRNA targets in Plk3.Plk3, one of Polo-like kinase family members, is involved in the regulation of cell cycle progression and DNA damage response. In this study,we clone Plk3 3’UTR which contains ARE and miRNA binding sites.We also clone Plk 3’UTR which contains ARE only.We determined Plk3 3’UTR controls its RNA stability.ARE determined Plk3 RNA stability.
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Wu, Ying Chung, and 巫盈忠. "Mechanism maintaining the stability of pSW200 from Pantoea stewartii." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/66704430322388665399.
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博士長庚大學
生物醫學研究所
98
Plasmid pSW200, one of the thirteen plasmids in Pantoea stewartii SW2, contains an origin of replication that is homologous to that of ColE1. This plasmid has a copy number of 13 and is stably maintained in Escherichia coli HB101. This study demonstrates that pSW200 contains a 9-bp UP element, 5’-AAGATCTTC, which is located immediately upstream of the -35 box in the RNAII promoter. A transcriptional fusion and in vitro transcription studies reveal that deleting this 9-bp sequence reduces the activity of the RNAII promoter. The same mutation also reduces the number from 13 to 5, as well as the plasmid stability. When a similar sequence in a ColE1 derivative, pYCW301, is mutated, the copy number of the plasmid also declines from 34 to 16 per cell. Inserting this 9-bp sequence increases the copy number of the plasmid, pYCW303, from 12 to 28 per cell. Additionally, inserting this 9-bp sequence stabilizes an unstable pSW100 derivative, pSW142KW, which also contains a replicon resembling that of ColE1, indicating the importance of this sequence in maintaining the stability and copy number of the plasmid. In conclusion, most of ColE1-type plasmids have the 9-bp sequence upstream of the -35 box in the RNAII promoter, which is the binding site for the α-subunit of RNA polymerase, for efficient synthesis of RNAII and maintenance of the stability of the plasmids in the ColE1 family. ColE1 plasmid is known to contain three 5’-GATC methylation sites in RNAIIp, two of which, at -43 and -32, are also present in pSW200. Our fusion study established that mutating the sequence at -43 in pSW200 to 5’-AATC does not affect the activity of RNAIIp or plasmid stability, indicating that methylation at this site may not be important to RNAII synthesis.
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Fu-Wen, Lin, and 林富文. "The Study of Chinese Stability Mechanism during Hu Jintao Era." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/f7t452.
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碩士環球科技大學
公共事務管理研究所
102
Following mainland China’s great change, from a developing country to a developed country, and the rapid economic development, many social problems have reared their heads. Usually, when social problem become more widespread and cemented, social movements are formed. Right now, in mainland China, the social movements represent the anger of people being unjustly ruled, an action of protests against the higher ruling bodies. Social protests all showed the same characteristics, the vitality of a protest group and the corruption of the representative country’s government. Their methods of protest include demonstrations, striking, causing chaos and attacking the government institutes offices that represent the party that is asserting the most pressure. Right now, China has entered an accelerated phase of its social reform. While facing its country’s rapid industrialization and urbanization, there are also a myriad of social problems to deal with. At present, mainland China’s main social issues include: arrear wages due to government enterprise reformation, farm villages’ problems, controversial court decision, compulsory property sales, the corruption of government official, and environmental pollution. If mainland China’s government don’t proceed stabilization mechanisms to establish some control and keep ignoring these social problems, it would not only lower the efficiency of the cultural reform (reform and opening – up policy), but also endanger mainland China’s national security. Thus, mainland China is using “stabilization mechanisms” to solve all types of social problems and protests. This thesis aims at research into the “stabilization mechanism”, specifically in mainland China. The study will attempt to discover and understand its system, organizations, operational modes and the pros and cons it brings to its society.
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Karparov, Krassimir Nikolov. "Slope stability analyses in complex Geotechnical conditions – Thurst failure mechanism." Thesis, 2007. http://hdl.handle.net/2263/23040.
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In this thesis a previously unknown mechanism of failure in multilayered slope profiles is identified. In some conditions this mechanism does not confirm to the known failure models (relating to circular failure) used in slope stability analysis. For this reason, major failures have occurred in the artificial cuts despite the fact that the limit equilibrium methods suggest that these cuts would be stable. The limit equilibrium methods were originally created to apply to earth dam walls. In the open pit mining environment, where we face inhomogeneous and inclined multilayered structures, the assumptions of these limit equilibrium methods appear to be inapplicable (e.g. assumption for the equal shear strength along the failure surface). Analysis starts with a general picture of the stress state in the highwall slope, given extant geological conditions and rock properties. The study then focuses on a comparison of the crack-tip stress changes in the rockmass with and without inclusions at the microscopic level. Basing some assumptions on binocular microscope observations of grain structures, it is possible to measure the size of the different inclusions and show that the microscopic carbon flakes present in the rock fabric make a major contribution to the failure process in a mudstone layer in the slope. The approach adopts the fracture-process zone ahead of a crack tip as the controlling parameter of flaw propagation in rock. Flaw coalescence, which is poorly accounted for in current fracture models, is attributable to two phenomena: the flaw propagation due to high level of applied stress; and the linking of fracture-process zones due to the small distance between neighbouring flaws. A condition of flaw coalescence is given based on these two mechanisms. This development allows defining of two zones along the failure surface (frictional and cohesive). In the slope-stability field the shear strength of the rock along the failure plane is a composite function of cohesive and frictional strength. For instance, the relaxation stress normal to bedding, induced by overburden removal, provides an investigation method for the determination of the weakest minerals, which may act as flaws for fracture propagation in low-porosity rock. A method has been developed to determine the critical stress for tensile fracture propagation due to the rock structure and the stress reduction normal to bedding. A proposed failure mechanism is based on the polygonal failure surfaces theory developed by Kovari and Fritz (1978), Boyd’s field observations (1983), Stead and Scoble’s (1983) analyses, Riedel (1929) Shear Fracture Model, Tchalenko and Ambraseys (1970), Gammond’s (1983) and Ortlepp (1997) observations for natural shear failures, computer modelling by McKinnon and de la Barra (1998), the results of many laboratory experiments reported by Bartlett et al. (1981) and the author’s experience. The proposed failure mechanism evaluates stability of the artificial slope profile due to the embedded weak layer structure, layer thickness, layer inclination and depth of the cut. On the basis of the observations and the above-mentioned modified fracture model, the slope profile is divided into two blocks; passive and active blocks. With this new model, it is possible to calculate slope safety factors for the slope failure cases studied in the industry. It has been found that, whereas the conventional slope stability models predict stable conditions, the new model suggests that the slope is only marginally stable (i.e. that failure can be expected).Thesis (PhD(Mining Engineering))--University of Pretoria, 2007.
Mining Engineering
unrestricted
50
Hung, Hui-Chih, and 洪慧芝. "Conformational stability and catalytic mechanism of human placental alkaline phosphatase." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/90241852106746682373.
Full textAbstract:
博士國防醫學院
生命科學研究所
87
Human placental alkaline phosphatase is a homodimeric metalloenzyme containing two zinc ions and one magnesium ion. The X-ray structure of E. coli enzyme has been refined to 2.0 ?resolution, however, no tertiary structure of the enzyme from other sources is yet available. In this dissertation, my research is aimed to the study of conformational stability and the role of magnesium ion in the catalytic mechanism of human placental alkaline phosphatase. I investigate the denaturation-renaturation process of the enzyme by its sensitivity to chemical denaturants, guanidinium chloride (GdmCl) or urea. Physical methods, e. g., fluorescence, circular dichroism, and ultracentrifugation, or functional properties, i. e., enzyme activity were used to explore the structure change induced by the denaturants. My results clearly indicate that a stable intermediate state is significantly populated in the GdmCl-induced unfolding process. A clear biphasic unfolding phenomenon was observed. The biphasic phenomenon is not a salt effect and is a simultaneous dissociation-denaturation process. The dimeric structure of th enzyme is thus quite stable, an intact folding monomer does not exist during GdmCl-induced unfolding. Similar chemical stability was also observed in urea denaturation. However, more complex multiple intermediate states detected in urea denaturation indicates the differential stability of subdomains of the enzyme. The enzyme activity was inactivated only after substantial tertiary structure has been changed, suggesting that the active site region is more resistant to chemical denaturant than other structural domains. The urea denaturation of the placental enzyme is also a simultaneous dissociation-denaturation process. Folded monomer never existed in the unfolding process. Complete dissociation occurred only beyond 6 M urea. Besides protein folding, I am also interested in the kinetic behaviors of the placental enzyme, which is activated by magnesium ion but inhibited by zinc ion. The role of zinc ion in the enzyme molecule is essential for catalysis, however, excess zinc ion inhibited the enzyme activity. Magnesium ion stimulates the enzyme activity to reach a maximal level, which is a slow process. Magnesium ion also protects the enzyme against the inhibition by zinc. I have analyzed the kinetic behavior of the slow activation. I proposed a plausible mechanism to explain the zinc inhibition and magnesium activation from the point of view for the enzyme structure at the active site region. I have also analyzed the enzyme activity in a biomembranous mimicking reverse micellar system. For the assay of alkaline phosphatase, p-nitrophenyl phosphate is used as the substrate. After hydrolysis, 4-nitrophenolic anions are yellow in alkaline solution. I observed the partitioning of 4-nitrophenol, which is colorless in its non-ionized form, in reverse micellar system. My results clearly indicate that the apparent pKa values of 4-nitrophenol are sensitive to the buffer used and also to the water content of the reverse micellar system. 4-nitrophenol has affinity with the surfactant AOT in carbonate buffer. Binding of 4-nitrophenol with the anionic surfactant polar head hinders ionization resulting in elevation of the pKa value of the phenolic -OH group, which occurs in a gradient manner with the most basic -OH at the interface region. Binding of 4-nitrophenol with AOT was affected by the 2-amino-2-methylpropanol buffer, which perturbates the partition of 4-nitrophenol between the water pool and interface. The perturbation of 4-nitrophenol partition in AOT-reverse micelles in 2-amino-2-methylpropanol buffer is due to the amino group of the buffer molecule, because tert-butylamine, rather than isobutanol, induced the replacement.