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1
Mrowicki, Anna. "Disordered eating in gastrointestinal disorders." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/88064/.
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This thesis consists of three chapters, a literature review, an empirical paper, and a reflective paper. Chapter one is a critical review of case study research on Disordered Eating (DE) in Gastrointestinal disorders (GId). Following both database and manual searches, twelve case study reports, describing 29 cases, were included and reviewed. The case study data shows there be a relationship between DE and GId, though the nature and direction of this relationship remains unclear. Possible risk factors for the onset of DE behaviours in the GId population are identified and discussed, as are suggestions for future research. Chapter two is a quantitative research study looking at DE in people with Crohn’s Disease (CD), compared to the general population. Participants in both groups (CD and control) completed self-reported, standardised measures of eating attitudes/behaviours and mood. The prevalence of DE was shown to be higher for people with CD compared to the general population, with females with CD shown to be most at risk of developing DE behaviours. In addition, anxiety and depression in children is highlighted as a possible risk factor for the development of DE in CD, in children. Clinical implications and directions for future research are discussed. Chapter three is a reflective account exploring the researcher’s research journey, from beginning to end. In this paper the choice of thesis topic is discussed, as are the researcher’s associated thoughts and feelings. The researcher’s epistemological position in relation to the methodology and natural style is also explored.
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Arnold, Marla N. "Validating a model of risk factors associated with eating disorder risk in adolescents." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1148575712.
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Newton, Angus William. "Charge transfer and disorder broadening in disordered transition metal alloys." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343931.
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Eavy, Geoffrey B. J. "Construing disordered minds as disordered brains : an alternative approach to mental pathology." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416904.
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Chung, Marilyn. "DISORDERED EATING AMONG NONBINARY INDIVIDUALS." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/dissertations/1876.
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Research on influences of eating disorders have informed diagnosis and treatment of eating disorders, particularly for White cisgender women. A Perfect Biopsychosocial Storm is a theory of influences of disordered eating development: sociocultural influences of rigid body shape and size ideals, high rates of trauma and violence, experiences of objectification and sexualization, and biological changes (Maine & Bunnell, 2010). For transgender individuals, recent findings suggest disparities and negative mental health outcomes such as elevated prevalence of disordered eating, body image concerns, and self-reported disordered eating. For transgender men and women, researchers found that disordered eating may be related to attempts to masculinize/feminize the body, through effects like suppression of weight and secondary sex characteristics. For nonbinary individuals, motivations are unclear regarding masculinization/feminization. Further, while previous research has implicated experiences of marginalization in reduced body appreciation, impact on disordered eating behaviors in nonbinary individuals have yet to be explored. This study addressed gaps in research regarding experiences of nonbinary individuals with disordered eating. Through Grounded Theory qualitative analysis, I developed a framework to understand disordered eating among nonbinary individuals. Disordered eating was the surface-level manifestations of experiences such as trauma, distress surrounding bodily changes in puberty, and marginalization. Repeated marginalization, like misgendering and identity erasure, created conditions of shame to be associated with identity and self. Shame is a universal emotion that occurs when one does something they perceive as social transgressive and, thus, prevents connection. Shame motivates individuals to reduce socially transgressive behavior to increase connection with others. When one experiences marginalization and repeated shame surrounding identity, identity and self then can be experienced as a social transgression that prevents belonging. For example, participants described feelings of shame in comparison to the stereotypical image of a nonbinary person (White, masculine-leaning/androgynous, thin, tall). Disordered eating facilitated emotional coping, and, for some participants, helped achievement of gender presentation. Disordered eating also was associated with consequences of further shame around eating behaviors, and feelings of lack of control. Recovery and healing was supported through combating shame and disempowerment: being seen and empowerment through choice.
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Vispa, Alessandro. "Dynamics of disordered systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/404444.
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Disordered systems are ubiquitous in nature and their study is complicated and often leads to controversial results. In any case, the important role of such systems in science and technological applications should not be ignored.
The characteristic properties of such systems seem to be driven by a fundamental feature, the degrees of freedom. Although many problems still remain matter of debate, the challenge posed in recent decades in the understanding of the impact of disorder in the physical behavior of materials is of considerable scientic interest.
An exact description of a disordered phase is not possible since it is a many-body problem hard to model. However, for some materials it is possible, upon cooling, to preserve the disordered liquid-like structure having a state of high regularity. Therefore, for the so-called glass formers, it is possible to freeze some degrees of freedom obtaining a glass that presents the irregularity of a liquid with the high viscosity of a solid below the melting temperature Tm.
The aim of the present PhD thesis is to present our understanding of disorder in related experimental approaches using three different pure compounds: two plastic crystals (1-Chloroadamantane and Freon113) and a liquid (Glycerol). To understand the behavior of these kinds of materials neutron scattering and dielectric spectroscopy have been used. These two powerful techniques allow us to investigate the dynamics of disordered phases on a picosecond time scale. Furthermore, given the complexity of these disordered phases, data analysis and model selection have been performed with a Bayesian approach that provides a solid statistical ground bases on probability distribution functions.
Such methods have been applied to study of the above mentioned compounds dynamics in order to give an explanation of some open questions: the microscopic origin of the plastic-plastic transition in 1-chloroadamantane (C10H15Cl), the high fragility and the correlation between kinetic and thermodynamic fragility in freon113 (Cl2FC-CClF2) and the dynamics, accompanied by a robust model selection, of one of the most studied glass former compound, glycerol (C3H8O3).
In addition, a brief overview of the theoretical background for neutron scattering and dielectric spectroscopy, as well as a description of the experimental setup and the consequent data treatment and analysis, are given to deliver a comprehensive and consistent view of the topic under consideration.
The results, presented in this work of thesis, represent a small step in a deeper understanding of disordered phases dynamics, giving a base for further investigations.Los sistemas desordenados son ubicuos en la naturaleza y su estudio es complicado y con frecuencia conduce a resultados controvertidos. En cualquier caso, el papel importante de este tipo de sistemas en aplicaciones científicas y tecnológicas no debe ser ignorada. Las propiedades características de tales sistemas parecen estar impulsadas por una característica fundamental, los grados de libertad. Aunque muchos problemas siguen siendo materia de debate, el desafío planteado en las últimas décadas en el entendimiento del impacto del desorden en el comportamiento físico de los materiales es de considerable interés científico. Una descripción exacta de una fase desordenada no es posible, ya que es un problema de muchos cuerpos difícil de modelar. Sin embargo, para algunos materiales, es posible, tras el enfriamiento, conservar la estructura desordenada del líquido con un estado de alta regularidad. Por lo tanto, para los denominados glass-formers, es posible congelar algunos grados de libertad obteniendo un vidrio que presenta la irregularidad de un líquido con la alta viscosidad de un sólido por debajo de la temperatura de fusión Tm. El objetivo de la presente tesis doctoral es presentar nuestra comprensión del desorden en los enfoques experimentales relacionados utilizando tres diferentes compuestos puros: dos cristales de plástico (1-Chloroadamantane y Freon113) y un líquido (Glycerol). Para entender el comportamiento de este tipo de materiales se han utilizado scattering de neutrones y espectroscopía dieléctrica. Estas dos técnicas nos permiten investigar la dinámica de las fases desordenadas en una escala de tiempo de picosegundos. Por otra parte, dada la complejidad de estas fases desordenadas, análisis de datos y la selección del modelo se han realizado con un enfoque bayesiano que proporciona una sólida base estadística basada sobre las funciones de distribución de probabilidad. Tales métodos se han aplicado al estudio de la dinámica de los compuestos antes mencionados con el fin de dar una explicación de algunas preguntas abiertas: el origen microscópico de la transición plástico-plástico en 1-chloroadamantane (C10H15Cl), la alta fragilidad y la correlación entre la fragilidad cinética y termodinámica en freon113 (Cl2FC-CClF2) y la dinámica, acompañada por una robusta selección de modelo, de uno de los compuestos más estudiados, glycerol (C3H8O3). Los resultados, presentados en este trabajo de tesis, representan un pequeño paso para una comprensión más profunda de la dinámica de las fases desordenadas, dando una base para futuras investigaciones.
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Gorokhov, Denis A. "Dynamics of disordered systems /." [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13070.
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Peil, Oleg E. "Theory of Disordered Magnets." Doctoral thesis, Uppsala universitet, Institutionen för fysik och materialvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9528.
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Studying magnetic properties of disordered alloys is important both for the understanding of phase transformations in alloys and from the point of view of fundamental issues of magnetism in solids. Disorder in a magnetic system can result in unconventional magnetic structures, such as spin glass, which have rather peculiar features. In this Thesis, a rather general approach to studying disordered magnetic alloys from first principles is presented. Phase transformations and magnetic behavior of crystalline substitutional alloys are considered. This approach is exemplified by calculations of an archetypical spin-glass material: the CuMn alloy. First, a general theoretical framework for the description of the thermodynamics of disordered magnetic alloys is given. It is shown that under certain conditions, a complex magnetic system can be reduced to an effective system containing no magnetic degrees of freedom. This substantially simplifies the investigation of phase transformations in magnetic alloys. The effective model is described in terms of material-specific interaction parameters. It is shown that interaction parameters can be obtained from the ground-state property of a disordered alloy which are in turn calculated from first principles by means of highly accurate up-to-date numerical techniques based on the Green's function method. The interaction parameters can subsequently be used in thermodynamic Monte-Carlo simulations to produce the atomic and magnetic structures of an alloy. An example of calculations for the Cu-rich CuMn alloy is given. It is demonstrated that the atomic and magnetic structure of the alloy obtained by the presented approach agrees very well with the results of neutron-scattering experiments for this system. Moreover, numerical simulations enable one to predict the ground state structure of the alloy, which is difficult to observe in experiment due to large atomic diffusion barriers at temperatures close to the temperature of the phase transformation. A general description of a spin glass is given, and difficulties of modeling this type of magnetic systems are discussed. To overcome the difficulties, improved Monte-Carlo methods, such as parallel tempering, overrelaxation technique, and finite-size scaling method of analysis, are introduced. The results for the CuMn alloy are presented.
9
Wicks, James David. "Studies of disordered materials." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359538.
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Astell, Arlene Jean. "Disordered speech in dementia." Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/3992/.
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What is the effect on language of the progressive degenerative disorder, Alzheimer's disease (AD)? What are the functional consequences of this illness, particularly for speech? The majority of accounts interpret speech disorder in AD as reflecting underlying semantic disruption. In contrast I apply current theories of lexicalization in speech production to the speech disorder. Four competing hypotheses are derived from a two-stage model of lexicalization in speech production. This model contains separate semantic, lexical and phonological representations. Data are collected from patients with probable AD and age-matched controls using standard psycholinguistic techniques. The data support an explanation of progressively impaired higher level cognitive processing which interacts with impaired semantic to lexical processing in speech production.
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Fricke, Niklas, Sebastian Sturm, Marc Lämmel, Sebastian Schöbl, Klaus Kroy, and Wolfhard Janke. "Polymers in disordered environments." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-198948.
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Using a combination of analytical theory and newly developed numerical algorithms, we analyze the most pertinent conformational characteristics of three paradigmatic types of polymers in disordered environments: (i) flexible polymers in quenched, self-similar disorder as represented by a self-avoiding random walk on a critical percolation cluster, (ii) semiflexible polymers in quenched, steric disorder as represented by an equilibrium hard-disk fluid and (iii) semiflexible polymers subject to the random energy landscape that emerges from a surrounding network of similar semiflexible polymers.
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Butler, Paul. "Characterisation of disordered structures." Thesis, University of Kent, 2017. https://kar.kent.ac.uk/62479/.
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In this thesis I will look at how large, complex structures can be interpreted and evaluated using an information theoretic approach. The work specifically investigates techniques to understand disordered materials. It explains a novel framework using statistical methods to investigate structural information of very large data sets. This framework facilitates understanding of complex structures through the quantification of information and disorder. Large scale structures including granular media and amorphous atomic systems can also be processed. The need to deal with larger complex structures has been driven by new methods used to characterise amorphous materials, such as atomic scale tomography. In addition, computers are allowing for the creation of larger and larger data sets for researchers to analyse, requiring new techniques for storing and understanding information. As it has become possible to analyse large complex systems there has been a corresponding increase in attempts to scientifically understand these systems. New, man-made, complex systems have emerged such as the stock market and on-line networks. This has boosted interest in their interpretation, with the hopes they can be more easily manipulated or controlled. Crystallography has been applied to great effect in biology, having been used to discover the structure of DNA and develop new drugs (UNESCO,2013). However it only describes crystal structure, which can be a drawback as a large majority of matter is amorphous. As such it is hoped that interpreting and understanding disorder may lead to similar breakthroughs in disordered materials. Entropic measures such as the mutual information and Kullback Leibler Divergence are used to investigate the nature of structural information and its impact on the system. I examine how this information propagates in a system, and how it could quantify the amount of organisation in a system that is structurally disordered. The methodology introduced in this thesis extracts useful information from large data sets to allow for a quantification of disorder. The calculated entropy for amorphous packings is generally less than 1 bit with Mutual information between 0 and 0.1 bits. The results verify direct correlation between Mutual Information and the correlation coefficient using various techniques. The Mutual information shows most information is obtained where sphere density is highest, following a similar trend to that of the Radial distribution function, and generally increasing for higher packing fractions. Evidence of the Random Close Packed (RCP) and Random Loose Packed (RLP) limits in two dimensions is shown, as well as evidence of both phases in time-lapsed 3D packings. The Kullback Leibler Divergence is also explored as a relative measure of disorder. This is achieved by calculating redundant information in packings so that areas of low and high order can be shown. Results present colour maps displaying relative information in random disk packings from which motifs can be identified. For higher packing fractions distinct borders form for areas of low and high information, particularly where crystallisation has occurred. Again, these results show an increase in information for more densely packed structures, as expected, with a Kullback Leibler divergence of between 0 and 1 bits. Finally I introduce the concept of self-referential order which provides a way to quantify structural organisation in non-crystalline materials, by referencing part of the system in a similar way to a unit cell. This allows a step forward in understanding and characterising disorder, helping to develop a framework to encode amorphous structures in an efficient way. These results show increasing information for higher packing fractions as well as further evidence of RLP and RCP limits around packing fractions of 0.54 and 0.64 respectively.
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Fricke, Niklas, Sebastian Sturm, Marc Lämmel, Sebastian Schöbl, Klaus Kroy, and Wolfhard Janke. "Polymers in disordered environments." Diffusion fundamentals 23 (2015) 7, S. 1-12, 2015. https://ul.qucosa.de/id/qucosa%3A14586.
Full textAbstract:
Using a combination of analytical theory and newly developed numerical algorithms, we analyze the most pertinent conformational characteristics of three paradigmatic types of polymers in disordered environments: (i) flexible polymers in quenched, self-similar disorder as represented by a self-avoiding random walk on a critical percolation cluster, (ii) semiflexible polymers in quenched, steric disorder as represented by an equilibrium hard-disk fluid and (iii) semiflexible polymers subject to the random energy landscape that emerges from a surrounding network of similar semiflexible polymers.
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Midic, Uros. "Genome-Wide Prediction of Intrinsic Disorder; Sequence Alignment of Intrinsically Disordered Proteins." Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/159800.
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Computer and Information SciencePh.D.
Intrinsic disorder (ID) is defined as a lack of stable tertiary and/or secondary structure under physiological conditions in vitro. Intrinsically disordered proteins (IDPs) are highly abundant in nature. IDPs possess a number of crucial biological functions, being involved in regulation, recognition, signaling and control, e.g. their functional repertoire complements the functions of ordered proteins. Intrinsically disordered regions (IDRs) of IDPs have a different amino-acid composition than structured regions and proteins. This fact has been exploited for development of predictors of ID; the best predictors currently achieve around 80% per-residue accuracy. Earlier studies revealed that some IDPs are associated with various human diseases, including cancer, cardiovascular disease, amyloidoses, neurodegenerative diseases, diabetes and others. We developed a methodology for prediction and analysis of abundance of intrinsic disorder on the genome scale, which combines data from various gene and protein databases, and utilizes several ID prediction tools. We used this methodology to perform a large-scale computational analysis of the abundance of (predicted) ID in transcripts of various classes of disease-related genes. We further analyzed the relationships between ID and the occurrence of alternative splicing and Molecular Recognition Features (MoRFs) in human disease classes. An important, never before addressed issue with such genome-wide applications of ID predictors is that - for less-studied organisms - in addition to the experimentally confirmed protein sequences, there is a large number of putative sequences, which have been predicted with automated annotation procedures and lack experimental confirmation. In the human genome, these predicted sequences have significantly higher predicted disorder content. I investigated a hypothesis that this discrepancy is not correct, and that it is due to incorrectly annotated parts of the putative protein sequences that exhibit some similarities to confirmed IDRs, which lead to high predicted ID content. I developed a procedure to create synthetic nonsense peptide sequences by translation of non-coding regions of genomic sequences and translation of coding regions with incorrect codon alignment. I further trained several classifiers to discriminate between confirmed sequences and synthetic nonsense sequences, and used these predictors to estimate the abundance of incorrectly annotated regions in putative sequences, as well as to explore the link between such regions and intrinsic disorder. Sequence alignment is an essential tool in modern bioinformatics. Substitution matrices - such as the BLOSUM family - contain 20x20 parameters which are related to the evolutionary rates of amino acid substitutions. I explored various strategies for extension of sequence alignment to utilize the (predicted) disorder/structure information about the sequences being aligned. These strategies employ an extended 40 symbol alphabet which contains 20 symbols for amino acids in ordered regions and 20 symbols for amino acids in IDRs, as well as expanded 40x40 and 40x20 matrices. The new matrices exhibit significant and substantial differences in the substitution scores for IDRs and structured regions. Tests on a reference dataset show that 40x40 matrices perform worse than the standard 20x20 matrices, while 40x20 matrices - used in a scenario where ID is predicted for a query sequence but not for the target sequences - have at least comparable performance. However, I also demonstrate that the variations in performance between 20x20 and 20x40 matrices are insignificant compared to the variation in obtained matrices that occurs when the underlying algorithm for calculation of substitution matrices is changed.
Temple University--Theses
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Mason, Suzanne M. "Body size and shape perception in eating disordered and non-eating disordered women." Thesis, University of Newcastle Upon Tyne, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493088.
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It is suggested that the media is a contributing factor to the obsession with the perfect body in Western society, and the associated rise in eating disorders. One of the key features of the eating disorders anorexia nervosa and bulimia nervosa is a disturbance in body size and shape. Researchers disagree on how this can be quantified. Previous methods have only produced a percentage over or underestimation of body size, rather than a representative image.
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Romanini, Michela. "Relaxation dynamics in disordered systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/317384.
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The nature of the glass transition and of the glassy state is a fundamental and still unsolved problem of condensed matter physics. Many liquids can be supercooled below their melting point without crystallizing, that is, without acquiring translational and orientational order. As the temperature of a supercooled liquid is lowered, the characteristic timescale of moleuclar motions, called relaxation time, increases until it becomes comparable to the timescale of human experimentation. This takes place at the glass transition temperature and leads to a non-equilibrium state of matter, called a ¿structural glass¿, in which a liquid-like lack of order is combined with solid-like elastic properties. Glass transitions are also observed in systems where there is only orientational disorder, such as orientationally disordered (OD) crystals or plastic crystals, which are translationally ordered solids in which the constituent molecules display reorientational motions about their centres of mass. Upon supercooling an OD crystal, the orientational disorder can ¿freeze¿, yielding a so-called ¿orientational glass¿.
In molecular materials forming structural or orientational glasses, the most important molecular dynamics process is the cooperative motion of the molecules, referred to as primary relaxation, whose freezing marks the transition to the glass state characterized by static disorder. The main difference between orientational and structural glasses is that in the former the freezing involves exclusively the rotational degrees of freedom of the molecules, while in the latter all six molecular degrees of freedom (i.e., both orientational and translational ones) are frozen. Orientational glasses are therefore systems with fewer degrees of freedom than structural glasses. This simplification, together with the fact that many OD phases are characterized by a crystal lattice with high symmetry, makes OD phases a model playground to investigate the nature of the glass transition. Other than the primary relaxation, there can be also so-called ¿secondary relaxations¿, usually characterized by shorter relaxation time than the primary process. Secondary relaxations may have different origins; for example, they can be due to conformational fluctuations or intramolecular vibrations; in many cases a special kind of secondary relaxation is observed, which is the single-molecule precursor process of the primary relaxation.
This thesis focuses on the effect of pressure and temperature on the dynamics of several pure compounds and binary mixtures forming structural or orientational glasses. We present a comparative study between two structural glass formers (ternidazole and the mixture of m-fluoroaniline with m-xylene), a plastic binary mixed crystal (neopenthyl alchol and neopentyl glycol), and two materials displaying statistical orientational disorder (2-adamantanone and pentachloronitrobenzene). In all cases a primary relaxation is present, associated with the collective motion of the molecules, and in most cases also secondary relaxations are observed. For each material, we analyse the temperature- and pressure-dependence of the various molecular relaxation and discuss the origin of secondary processes. One of the most important results of the thesis is the presence of secondary relaxations also in systems with low-dimensional disorder that behave similarly to the secondary relaxations observed in structural glasses.La naturaleza de la transición vítrea es un problema fundamental y aún no resuelto de la física de la materia condensada. Muchos líquidos pueden ser superenfriados por debajo de su temperatura de fusión sin que cristalicen, es decir, sin que adquieran orden traslacional y orientacional. Cuando la temperatura de un líquido superenfriado baja, el tiempo característico de los movimientos moleculares, llamado tiempo de relajación, aumenta hasta llegar a tiempos comparables con el tiempo característico de los experimentos y de la observación humana. Esto ocurre a una temperatura llamada temperatura de transición vítrea y lleva a un estado de non-equilibrio del material llamado ¿vidrio estructural¿, en el que la ausencia de orden de largo alcance típica del estado líquido se combina con las propiedades elásticas propias de un sólido ordenado. Las transiciones vítreas se pueden observar también en sistemas caracterizados por desorden exclusivamente orientacional, como en los cristales orientacionalmente desordenados (OD) o cristales plásticos. Estos son sólidos traslacionalmente ordenados en los que las moléculas tienen movimientos de reorientación alrededor de sus centros de masa, que están fijos. Superenfriando un cristal OD se obtiene un ¿vidrio orientacional¿ en el cual este desorden orientacional está congelado. El proceso dinámico más importante que caracteriza los materiales moleculares que forman vidrios estructurales u orientacionales es el movimiento cooperativo de las moléculas conocido como relajación primaria. Su congelamiento marca la transición al estado vítreo caracterizado por un desorden estático. La diferencia principal entre los vidrios orientacionales y estructurales es que en los primeros el congelamiento involucra sólo los grados de libertad de rotación, mientras que en los segundos todos los seis grados de libertad moleculares (orientacionales y traslacionales) están congelados. Por tanto, los vidrios orientacionales son sistemas con menos grados de libertad respecto los vidrios estructurales y pueden considerarse como sistemas modelo para investigar la transición vítrea, ya que además muchas fases OD están caracterizadas por redes cristalinas de alta simetría. Además de la relajación primaria, existen también relajaciones secundarias caracterizadas por tiempos de relajación más cortos con respecto al proceso primario. Estas relajaciones secundarias pueden tener diferentes orígenes: por ejemplo, pueden ser debidas a fluctuaciones de la conformación molecular o a vibraciones de enlaces intramoleculares; en muchos casos se observa una relajación secundaria que es considerada como la precursora del proceso primario (relajación Johari-Goldstein). Esta tesis está enfocada en el estudio de los efectos de la presión y de la temperatura sobre la dinámica de algunos compuestos puros y mezclas binarias, los cuales forman vidrios estructurales u orientacionales. Se presenta un estudio comparativo entre dos vidrios estructurales (ternidazole y la mezcla de m-fluoroanilina con m-xileno), un cristal plástico binario (formado por neopenthyl alcohol y neopentyl glycol), y dos materiales que presentan desorden estadístico (2-adamantanona y pentacloronitrobenceno). En todos los casos se observa una relajación primaria asociada a los movimientos colectivos de las moléculas y en la mayoría de los casos se observa también relajaciones secundarias. Para cada material se analiza la dependencia de diferentes relajaciones con la temperatura y con la presión y se discute el origen de los procesos secundarios. Uno de los resultados importantes de la tesis es que en sistemas con desorden de baja dimensionalidad, pueden aparecer relajaciones secundarias que obecen a patrones similares a las encontradas en vidrios estructurales
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Martínez, García Julio César. "Dynamics in orientationally disordered solids." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/35856.
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The key features of dynamics of ultraslowing glass forming systems are their universality in diversity. Its
origin is recognized as one of the greatest challenges of condensed matter physics and materials
engineering in the XXI century. Similar phenomena are observed on approaching the glass transition in
low molecular weight supercooled liquids, polymers, colloidal fluids as well as in solids, for instance in
orientationally disordered crystals, spin glass-like magnetic, vortex glasses. Pre-vitreous dynamics is also
proposed as a general reference for the category of complex liquids/soft matter systems.
The upsurge of the primary relaxation time or related dynamical properties is the basic physical
phenomena of the still mysterious previtreous behavior. This means a much more pronounced slowing
down than the Arrhenius pattern observed far above the glass transition temperature. Portraying this
behavior constitutes one of key checkpoints for theoretical models developed to unwind the glass
transition puzzle. However, none of the aforementioned features can answer the understanding that
governs the increase of relaxation time in liquids upon cooling.
In this thesis we focus on the above questions studying the dynamics of some materials for which their
molecules can retain a translational order being orientationally disordered between them upon cooling,
which are referred to plastic phases or orientationally disordered (OD) crystalline phases. The work
presented in this thesis potentially extends the knowledge of dynamics of OD phases and orientationally
glasses (OG), a research topic which has gained interest during the last decades.
Through this study, especial attention has been devoted to the phenomenological equations accounting
to the temperature dependence of the mean relaxation time describing the orientational dynamics .The
study was carried out by the use of BDS as well as two complementary experimental techniques. We
show distortion-sensitive and derivative-based empirical analysis of the validity of leading equations for
portraying the previtreous evolution of primary relaxation time. A new method for studying the dynamics of
glass forming systems is introduced and the minimization procedure is validated and discussed.
We present the results divided in two topics, the dynamics of the pure compounds and mixed crystals and
the derivative analysis through different existing models.
In the first topic we focus on the dynamics of the pure compounds and mixed crystals formed between
cycloheptanol and cyclooctanol as well as the a-relaxation dynamics of 1-cyano-adamantane and its
mixtures with 1-chloro-adamantane. The second topic is divided in two groups of models, linearized and
non-linearized models. In the linearized models we show the application of the derivative based,
distortion-sensitive analysis to liquid crystals (LC) and OD phases. We also discuss the results concerning
to the cases of the olygomeric liquid epoxy resin (EPON828), neopentylalcohol and neopentylglycol
mixture, isooctylcyanobiphenyl and propylene carbonate. The possible empirical correlations between one
of the linearized models with the universal pattern for the high frequency wing of the loss curve for primary
relaxation time for LCs and OD phases is also shown.
In the final part we show that the form of the equation recently introduced by Mauro et al. does not allow a
similar straightforward linearization procedure. Unlike the previous models, the involved parameters are
not correlated with the slope and the intercept of a linear function. In order to solve this problem, we have
introduced the concept of the enthalpy space.
The evidences of the existence of crossovers as well as quantitative descriptions are discussed. We show
also a new procedure for detecting the crossover in a very easy way. A new kind of crossovers which
seems to be impossible to be detected by the classical Stickel transformation is presented.La principal característica de la dinámica de sistemas vítreos viscosos, es su universalidad en la diversidad. Su origen es uno de los mayores desafíos de la física de la materia condensada y de la ingeniería de materiales en el siglo XXI. La fenomenología típica de las fases vítreas se observan cerca de la transición vítrea en líquidos subenfriados de bajo peso molecular, polímeros, fluidos coloidales, así como en los sólidos con fases orientacionalmente desordenadas. La imposibilidad de explicar las causas del gran aumento del tiempo de relajación al enfriar un líquido, constituye uno de los problemas más importantes no resueltos en materia condensada. Con el objetivo de dar respuesta a dicha interrogante, se han propuesto modelos termodinámicos y dinámicos que han resultado inconsistentes. En esta tesis nos centramos en dicha problemática, estudiando la dinámica orientacional de algunos materiales que al ser enfriados pueden conservar un orden traslacional mientras que se conserva el desorden orientacional de las moléculas que los forman. Dichas fases se conocen como fases plásticas u orientacionalmente desordenadas (OD). El trabajo presentado en esta tesis amplía el conocimiento de la dinámica de dichas fases, un tema de investigación cuyo interés ha aumentado durante las últimas décadas. Se ha dedicado una atención especial a las ecuaciones fenomenológicas que describen la dependencia del tiempo de relajación con la temperatura. El estudio se ha llevado a cabo mediante el uso de espectroscopía dieléctrica de banda ancha, así como mediante el uso de técnicas experimentales complementarias. Se ha introducido un nuevo método para el estudio de la dinámica de los sistemas que dan lugar a fases vítreas. El método ha sido validado y discutido. Los resultados de esta tesis se presentan divididos en dos temas, por un lado, la dinámica de compuestos puros y de los cristales mixtos y, por otro, el análisis mediante el método derivativo aplicado a los diferentes modelos físicos existentes. En el primer tema nos centramos en la dinámica de los compuestos puros y los cristales mixtos formados por cicloheptanol y ciclooctanol, así como la dinámica de la relajación alfa en 1-ciano-adamantano y sus mezclas con 1-cloro-adamantano. El segundo tema se divide en dos grupos de modelos, los modelos lineales y no lineales. En los modelos lineales se muestra la aplicación del procedimiento de derivativo en los cristales líquidos (CL) y las fases OD. También se discuten los resultados relativos a los casos de la resina líquida (EPON828), la mezcla neopentil-alcohol y neopentil-glicol, el carbonato de propileno, así como el CL isooctilcianobifenil. Se discute también la existencia de posibles correlaciones empíricas entre uno de los modelos lineales con el patrón universal para la parte de alta frecuencia de la curva de pérdidas dieléctricas de la relajación primaria para las fases CL y OD. En la parte final se muestra que la forma de la ecuación introducida recientemente por Mauro et al. no permite la linearización mediante el método derivativo. A diferencia de los modelos anteriores, los diferentes parámetros no están correlacionados con la pendiente y el origen de coordenadas de una función lineal. Para resolver este problema, hemos introducido el concepto del espacio entálpico. Se analiza también la existencia de cambios de comportamiento dinámicos y se aportan descripciones cuantitativas. Se muestra también un nuevo procedimiento para detectar los cambios dinámicos de una manera fácil, que permite incluso detectar aquéllos que son obviados mediante el método clásico de Stickel.
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Wong, Eric Tsz Chung. "Electrostatics in intrinsically disordered proteins." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43451.
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Huxley, David W. "Diffraction studies of disordered materials." Thesis, University of Kent, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293796.
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Rodgers, Geoffrey John. "Topics in disordered systems theory." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329087.
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Fawcett, Ian D. "Structural studies of disordered molybdates." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320188.
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Sobiesierski, Z. "Optical spectroscopy of disordered systems." Thesis, University of Exeter, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374944.
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Nahm, In Hyun. "Two dimensional disordered electron systems." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330179.
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Mazarakis, Theodore. "Psychological dimensions of disordered sleep." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420923.
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Kaisari, Panagiota. "Neurocognitive processes in disordered eating." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8271/.
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The overall aim of this thesis was to better understand the specific cognitive and neural mechanisms that may serve as risk factors to the development of disordered eating behaviour. In Chapter 2, findings are suggestive of a novel mechanism guiding attention to food cues in overweight/obesity through working memory. Differential attentional processing of food cues was also found to be a predictor of weight gain at one-year follow-up. In Chapter 3, a systematic review of the evidence for an association between Attention Deficit Hyperactivity Disorder (ADHD) and disordered eating, suggests a moderate strength of between ADHD and disordered eating; a framework for future research was proposed to guide future studies on ADHD and disordered eating. Chapter 4 aimed to address some of the research gaps outlined in Chapter 3. Notably, in two independent studies, findings provide the first evidence for a direct relationship between inattentive symptoms of ADHD and binge/disinhibited eating behaviour. In Chapter 5, an experimental design was employed to investigate eating behaviour in ADHD using laboratory measures, in conjunction with self-report measures, along with performance-based tasks to assess specific cognitive constructs, and neural correlates of eating behaviour. This model can also be used to the study of other mental disorders associated with disordered eating behaviour. Overall, this thesis provides novel and theoretical insights into the role of attention in guiding eating behaviour. The findings can inform future research and may have implications for the management and treatment of individuals with overweight/obesity, ADHD and/or disordered eating.
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Kissel, Glen James. "Localization in disordered periodic structures." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/34990.
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Pinski, Sebastian. "Phonons in disordered harmonic lattices." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/57512/.
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This work explores the nature of the normal modes of vibration for harmonic lattices with the inclusion of disorder in one-dimension (1D) and three-dimensions (3D). The model systems can be visualised as a `ball' and `spring' model in simple cubic configuration, and the disorder is applied to the magnitudes of the masses, or the force constants of the interatomic `springs' in the system. With the analogous nature between the electronic tight binding Hamiltonian for potential disordered electronic systems and the isotropic Born model for phonons in mass disordered lattices we analyse in detail a transformation between the normal modes of vibration throughout a mass disordered harmonic lattice and the electron wave function of the tight-binding Hamiltonian. The transformation is applied to density of states (DOS) calculations and is also particularly useful for determining the phase diagrams for the phonon localisation-delocalisation transition (LDT). The LDT phase boundary for the spring constant disordered system is obtained with good resolution and the mass disordered phase boundary is verified with high precision transfer-matrix method (TMM) results. High accuracy critical parameters are obtained for three transitions for each type of disorder by finite size scaling (FSS), and consequently the critical exponent that characterises the transition is found as = 1:550+0:020 -0:017 which indicates that the transition is of the same orthogonal universality class as the electronic Anderson transition. With multifractal analysis of the generalised inverse participation ratio (gIPR) for the critical transition frequency states at spring constant disorder width k = 10 and mass disorder width m = 1:2 we confirm that the singularity spectrum is the same within error as the electronic singularity spectrum at criticality and can be considered to be universal. We further investigate the nature of the modes throughout the spectrum of the disordered systems with vibrational eigenstate statistics. We find deviations of the vibrational displacement uctuations away from the Porter-Thomas distribution (PTD) and show that the deviations are within the vicinity of the so called `bosonpeak' (BP) indicating the possible significance of the BP.
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Kerr, Hannah Elin. "NMR crystallography of disordered cocrystals." Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12037/.
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Crystallographic disorder is common in the solid state but it is rarely investigated explicitly despite having a fundamental impact on the solid-state structure of a material. In this work, nuclear magnetic resonance (NMR) crystallography methods are utilised to achieve a detailed understanding of the structure and dynamics of solid organic systems containing disorder. Several new cocrystal systems are studied, each containing a topical drug molecule (caffeine, naproxen or furosemide) and each serving to demonstrate how NMR crystallography can be applied to a variety of structural questions. Hydrogen bonding motifs are identified using single crystal X-ray diffraction experiments, where possible, and are subsequently verified by solid-state NMR. Alternative hydrogen bonding models are ruled out by comparison of experimental solid-state NMR data with density functional theory calculated shieldings, and proton transfer can be investigated by monitoring the energy of the system with respect to proton position. In a particularly challenging case, 2D solid-state NMR experiments go some way to identify the hydrogen bonds in a system that cannot be crystallised. Dynamic disorder of fragments and solvent molecules are characterised by variable temperature solid-state NMR, including analysis of relaxation times to establish energy barriers and rates of motion. A mechanism of motion is also proposed for dynamic acetone molecules in a new cocrystal solvate, which is supported by good agreement between experimental and simulated 2H static NMR line shapes. Finally, the current limit of NMR crystallography is identified with respect to the reproducibility of calculated NMR parameters following geometry optimisation. It is shown that the geometry optimisation protocol does not affect standard NMR crystallography investigations pertaining to atom assignment, but it is significant for cases where very subtle structural features are probed, such as NMR linewidths. Overall, NMR crystallography investigations allow a deeper understanding of solid materials to be achieved than would be possible with any single technique and this work highlights the applicability of such methods to complex materials containing disorder.
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Bosisio, Riccardo. "Thermoelectric conversion in disordered nanowires." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066212/document.
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Cette thèse porte sur la conversion thermoélectrique de nanofils semi-conducteurs désordonnés en configuration de transistor à effet de champ.On considère d’abord le régime de transport élastique à basse température. En utilisant un modèle d'Anderson 1D, on dérive des expressions analytiques pour le coefficient Seebeck typique d’un nanofil en fonction de la tension de grille, et on montre que celui-ci augmente fortement en bord de bande. Ces résultats sont confirmés par un calcul numérique du Seebeck, basé sur un algorithme de fonctions de Green récursif.On considère ensuite le régime inélastique où les électrons, assistés par les phonons, sautent entre états localisés. En résolvant numériquement le réseau de résistances aléatoires de Miller-Abrahams, on montre que le coefficient Seebeck peut atteindre des valeurs très élevées au voisinage des bords de bande du nanofil. La théorie de percolation de Zvyagin étendue au cas unidimensionnel nous permet de décrire qualitativement nos résultats. Par ailleurs, les échanges de chaleur entre électrons et phonons en bord de bande entraînent la formation de points chauds et froids à la surface du substrat, qui pourraient être utilisés pour le refroidissement de circuits électroniques. Cet effet est étudié pour un ensemble de fils en parallèle. Le facteur de puissance et la figure de mérite de ces systèmes sont aussi estimés.Enfin, on étudie un système général à trois terminaux en réponse linéaire. On calcule les coefficients de transport locaux et non-locaux, et les figures de mérite généralisées, puis l'on discute à l'aide de deux exemples la possibilité d’améliorer la performance d’une machine thermique quantique génériqueThis thesis is focused on thermoelectric conversion in disordered semiconductor nanowires in the field effect transistor configuration. We first consider a low temperature regime, when electronic transport is elastic. For a 1D Anderson model, we derive analytical expressions describing the typical thermopower of a single nanowire as a function of the applied gate voltage, and we show that it is largely enhanced at the nanowire band edges. Our results are confirmed by numerical simulations based on a Recursive Green Function calculation of the thermopower. We then consider the case of inelastic transport, achieved by phonon-assisted hopping among localized states (Variable Range Hopping). By solving numerically the Miller Abrahams random resistor network, we show that the thermopower can attain huge values when the nanowire band edges are probed. A percolation theory by Zvyagin extended to nanowires allows to qualitatively describe our results. Also, the mechanism of heat exchange between electrons and phonons at the band edges lead to the generation of hot and cold spots near the boundaries of a substrate. This effect, of interest for cooling issues in microelectronics, is showed for a set of parallel nanowires, a scalable and hence promising system for practical applications. The power factor and figure of merit of the device are also estimated.Finally, we characterize a general three-terminal system within the linear response (Onsager) formalism: we derive local and non-local transport coefficients, as well as generalized figures of merit. The possibility of improving the performance of a generic quantum machine is discussed with the help of two simple examples
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Scheffler, Falk. "Spin dynamics in disordered systems." Konstanz Hartung-Gorre, 2006. http://d-nb.info/990499073/04.
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Rimas, Zilvinas. "Sorption in disordered porous media." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/268094.
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The lattice-gas model of sorption in disordered porous media is studied for a variety of settings, using existing, updated and newly developed numerical techniques. Firstly, we construct an efficient algorithm to calculate the exact partition function for small lattice-gas systems. The exact partition function is used for detailed analysis of the core features exhibited by such systems. We proceed to develop an interactive Monte Carlo (MC) simulation engine, that simulates sorption in a porous media sample and provides real-time visual data of the state space projection and the 3d view of the sample among other parameters of interest, as the external fields are manipulated. The use of such tool provides a more intuitive understanding of the system behaviour. The MC simulations are employed to study sorption in several porous solids: silica aerogel, Vycor glass and soil. We investigate how the phenomena depend on the microstructure of the original samples, how the behaviour varies with the external conditions, and how it is reflected in the paths that the system takes across its state space. Secondly, we develop two methods for estimation of the relative degeneracy (the number of microstates that have the same value of some macroscopic variables) in the systems that are too large to be handled exactly. The methods, based on a restricted infinite temperature sampling, obtain equidegenerate surfaces and the degeneracy gradient across the state space. Combined with the knowledge of an internal energy of a microstate, it enables us to construct the free energy map and thus the equilibrium probability distribution for the studied projection of the state space. Thirdly, the jump-walking Monte-Carlo algorithm is revisited and updated to study the equilibrium properties of systems exhibiting quasi-ergodicity. It is designed for a single processing thread as opposed to currently predominant algorithms for large parallel processing systems. The updated algorithm is tested on the Ising model and applied to the lattice-gas model for sorption in aerogel and Vycor glass at low temperatures, when dynamics of the system is significantly slowed down. It is demonstrated that the updated jump-walking simulations are able to produce equilibrium isotherms which are typically hidden by the hysteresis effect characteristic of the standard single-flip simulations. As a result, we answer the long standing question about the existence of the first-order phase transitions in Vycor. Finally, we investigate sorption in several distinct topology network representations of soil and aerogel samples and demonstrate that the recently developed analytical techniques for random networks can be used to achieve a qualitative understanding of the phenomena in real materials.
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Walsh, Karen. "Gender differences in post-traumatic stress disorder and anger in mentally disordered offenders." Thesis, Royal Holloway, University of London, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604563.
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Females are more than twice as likely to have a diagnosis of Post-traumatic Stress Disorder (PTSD) making PTSD particularly relevant to female mentally disordered offenders (MDOs). Female offenders have been observed to report higher levels of trait anger and anger expression compared to males. Exploration of the relationship between anger and PTSD is in its infancy among MOOs. This study investigated gender differences in the levels of PTSD and anger and in the relationship between PTSD and anger in a sample of 66 MOOs using a cross sectional design. Participants completed self- report measures of posttraumatic symptomatology, trait anger, anger expression, depression, anxiety and social desirability. Results indicated that PTSD was particularly prevalent among female MOOs, which was independent of potential con founders, however none of the participants had received a formal diagnosis. A gender difference was found on the measure of trait anger in the univariate analysis but did not remain significant when controlling for confounding variables in the multivariate analysis. A gender difference was not found on measures of anger expression in the univariate and multivariate analysis. Consistent with previous research a positive relationship was found between PTSD symptomatology and trait anger, and this correlation remained significant for males and females separately. A positive relationship was found between PTSD symptomatology and anger expression, however this correlation remained significant for females only. However, a gender difference between the relationships of PTSD and trait anger and PTSD and anger expression was not found. The limitations and strengths of the study are outlined, and the clinical, theoretical and research implications of the findings discussed.
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Dubois, Alizee. "Dynamic cracks in disordered materials : interplay between microstructure disorder, wavefield and overail fracture." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX114.
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La propagation de fractures est le mécanisme fondamental amenant à la rupture brutale des matériaux. L’élément clé du problème est la concentration des contraintes en pointe de fissure qui rend le comportement macroscopique très sensible aux inhomogénéités de structure ou de chargement local. Autour de la pointe de fissure, une zone de process, renferme tous les processus dissipatifs impliqués dans la création des deux nouvelles surfaces. L’élastodynamique et la mécanique linéaire élastique de la fracture fournissent les bons outils pour décrire le phénomène dans le cas de la fracture dynamique. Néanmoins, à partir d’une certaine vitesse, des instabilités sont observée dans le comportement de la fissure. Dans les polymères fragiles tels que le polymethalcrylate de méthyle, des microfissures se développent en devant de front principal sur une zone de taille fonction de la vitesse de la pointe de fissure et supérieur à celle de la zone de process. L’organisation spatiale et temporelle de cet endommagement évolue avec la vitesse de la fissure et une organisation spatiale jusqu’au millimètre émerge. Gao and Rice en1986, les premiers, proposèrent de modéliser le front de fissure dans un solide 3D par une ligne élastique se propageant dans un champ d’obstacle représentant les défauts du matériau. A chacune de ses distorsions, dues à la rencontre d’un défaut, elle affecte en retour le chargement local. Un tel modèle gagna de l’ampleur lorsque les premières études statistiques des surfaces de fracture révélèrent un comportement « self-affine » de leur rugosité (Bouchaud et al, 1990). Tout un panel d’exposant de rugosité fut mesuré depuis. Le modèle de la ligne élastique a rencontré beaucoup de succès dans les cas quasi-statique. Il est maintenant temps de l’étendre à la fracture dynamique. Une nouvelle compréhension du phénomène de fracture dynamique et des instabilités mentionnées plus haut est attendue. Le principal objectif de cette thèse est de tester sur une expérience modèle les propriétés microscopique et macroscopique du front de fissure pour comprendre le couplage entre ses différentes échelles. Par ailleurs, une mise en évidence des limites expérimentales du modèle de ligne, dues à la complexité locale du front à l’échelle de l’endommagement en pointe de fissure. Une série de question est à se poser. L’étude fractographique des surfaces de fracture est une méthode prometteuse d’obtenir l’historique de la propagation du front de fracture au travers l’échantillon. Comment peut-elle être adaptée à la fracture dynamique? Quelles sont les informations accessibles par cette technique ? En fracture dynamique du PMMA, il est bien connu que le régime de fracture évolue de la fracture fragile à la fracture quasi-fragile aves développement de multi-endommagement en pointe de fissure. Quels sont les paramètres mécaniques qui contrôlent cette transition ainsi que l’organisation de l’endommagement ? Les instabilités mentionnées existant en fracture dynamique sont maintenant considérées comme des effets purement 3D qu’un modèle 2D de la pointe de fissure ne peut pas expliquer. Quel est le rôle de la longueur du font dans leur organisation ? En fracture, une instabilité se propage le long du front de fissure : les ondes de front « crack front waves » dans le plan de fissure et les « corrugation waves » en hors plan. Pouvons-nous mettre en évidence dans la dynamique du front de fissure des marqueurs de ces ondes ? Quel est leur rôle dans l’organisation de l’endommagement ?Dynamic crack propagation drives catastrophic material failures. A key aspect in the problem is the stress concentration at the tip of cracks, which makes the failure behavior observed at the macroscopic scale very sensitive to inhomogeneities in the material micro-structure, or, in local loading, down to very small scale. Stress concentration and redistribution of stresses during crack growth, indeed, couple many space and time scales. They stretch from the macroscopic dimension of the sample, L, down to the size of the so-called fracture process zone, which embeds all the dissipative process involved in the creation of new fracture surface area). Elastodynamics and continuum fracture theory a priori provide the relevant tools to describe dynamic crack growth. Still, at high enough speed several instabilities are observed. In brittle polymers like polystyrene or polymethylmethalcrylate (PMMA) for instance, micro-cracking starts occurring in the vicinity of the crack tip, in a zone of length-scale depending on the crack speed and larger than the fracture process zone. The space and time organization of these micro-cracking events evolves with crack speed and can present patterns up to the millimeter scale Since the pioneering work of Gao and Rice, 1986, it has been proposed to model crack propagation in a 3D solid as an elastic line moving through obstacles. The distortion in the crack front, in turn, increases locally the stress intensity factor. Such model gained momentum when the first statistical studies of crack surfaces revealed self-affine features for the roughness. A whole zoology of roughness exponent was measured since then. The elastic line model meet great success in the quasi static crack front modeling.In this context, it is now timely to extend it to dynamic fracture. This may should bring new insight on the dynamic crack problem and the instabilities mentioned above. The main objective of this work is to use a model experiment to study systematically the microscopic and macroscopic properties of a dynamic crack front. This thesis aims at understanding to what extend such a line model is valid experimentally despite the complex environment seen by the crack front due to the micro-cracks of the damage zone and the presence of micro-branches. Along these lines, here is a set of questions to address. Fractography is a promising method to probe the fracture history and to measure the fracture toughness of the material. How could the method evolve to be applicable to dynamic crack surfaces? What would be the available information on the material properties and the crack velocity? Dynamic fracture in PMMA is known to undergo a brittle to quasi brittle transition above a certain critical speed, which is smaller than the micro-branches threshold. What mechanical parameters control the statistical distribution of micro-crack nucleation centers? Dynamic crack instabilities are believed to be a 3D effect, no 2D model could justify them. What is the role of the crack front thickness in their organization and nucleation? In dynamic fracture, instabilities travel along the front, the in plane crack front waves (Morrissey and Rice, 1998) and the out of plane corrugation waves (J.R. Willis, 2012). Can we find, in the behavior of the crack front, some experimental evidences of these front waves? What is their impact on the damage organization?
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Lee, Soon-Gul. "Experimental study of the effects of disorder in weakly disordered superconducting aluminum films /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487588939089315.
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Brink, Susan Goldswain. "A comparative study of the dream content of eating-disordered and non-eating-disordered women." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30404.
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Dream theorists propose that dreams can balance conscious reality, and provide clues to unconscious processes complicating psychosomatic conditions. Little research has been done in the area of dreams and eating disorders. Based on data from a pilot study, and reports of eating-disordered women's dreams in the literature, the researcher hypothesised that eating-disordered women's dreams would contain a significant number of themes symbolizing the psychological states underlying their condition. Of particular interest was a sense of ineffectiveness, which has been the subject of many recent studies of eating-disordered women. The exploratory study compared the dream content of 12 eating-disordered and 11 normal women, aged 20 to 35 years. The 275 dreams were rated by 8 "blind" raters according to a 91-item eating disorder specific dream rating scale, which registered dream content such as attitudes of helplessness, images of anger, self-hate, and affect. A high level of inter-rater reliability was obtained. A questionnaire assessing motivational states (General Causality Orientation Scale; GCOS) was also administered. The data were analyzed by the independent t-test. The results showed strong significance in the occurrence of themes of ineffectiveness in the eating-disordered women's dreams (p = .001), which corresponded with the findings on the GCOS (p< .001). Also significantly present in the target group's dreams were themes of self-hate, anger, inability to nourish themselves, an obsession with weight, and the presence of negative emotions. An additional finding was a strongly significant presence of a sense of impending doom at the end of eating-disordered women's dreams (p < .001). These results suggest that dreams may provide an additional resource in understanding eating disorders.Education, Faculty of
Educational and Counselling Psychology, and Special Education (ECPS), Department of
Graduate
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Marchand, Stephanie Milbradt. "Disordered eating behaviors among collegiate athletes /." View online ; access limited to URI, 2007. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3284826.
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Nikolaou, Marios. "A Matter of Disorder : Monte Carlo Simulations of Phase Transitions in Strongly Disordered Systems." Doctoral thesis, Stockholm : Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4313.
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Kalyani, Tania. "Posttraumatic stress disorder and anger in mentally disordered offenders: does alexithymia mediate this relationship?" Thesis, University of London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589455.
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Early clinical observations and more recent clinical studies have identified that individuals with Posttraumatic Stress Disorder (PTSD) commonly experience difficulties with anger and anger expression. However, no exploration of this relationship has been undertaken in samples of mentally disordered offenders (MDOs), despite the high levels of PTSD and anger-related difficulties identified within this population. The current study explored the relationship between PTSD and anger in a sample of 44 mentally disordered male and female offenders. Participants completed self-report measures that examined posttraumatic symptomology, trait anger, anger expression and alexithymia. Results indicated that PTSD was prevalent within this sample although no participants had received a formal diagnosis. PTSD was tentatively related to trait anger, although this was no longer the case when the effect of gender was taken into account. PTSD and anger expression were also related, although PTSD did not predict anger expression when trait anger was controlled. Alexithymia was found to be predictive of trait anger. The findings indicate that a diagnosis of PTSD should be considered in samples of MDOs. Furthermore, interventions aimed at addressing anger and anger expression in the context of PTSD might be effective. Treatments for anger might also be effectively supplemented by addressing emotion regulation skills.
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Scott, Helen. "Attachment, narcissism and social rank in a group of anger-disordered and non-anger-disordered males." Thesis, University of Birmingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408972.
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Duckheim, Mathias. "Electrically controlled spin dynamics disordered semiconductors /." [S.l.] : [s.n.], 2008. http://edoc.unibas.ch/diss/DissB_8756.
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Sales, Pardo Marta. "Large Scale Excitations in Disordered Systems." Doctoral thesis, Universitat de Barcelona, 2002. http://hdl.handle.net/10803/1786.
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Disorder is present in many systems in nature and in many different versions. For instance, the dislocations of a crystal lattice, or the randomness of the interaction between magnetic moments. One of the most studied examples is that of spin glasses because they are simple to model but keep most of the very complex features that many disordered systems have. The frustration of the ground state configuration is responsible for the existence of a gap less spectrum of excitations and a rugged and complex free-energy landscape which bring about a very slow relaxation towards the equilibrium state. The main concern of the thesis has been to study what the properties of the typical excitation, i.e. those excitations that are large and contribute dominantly to the physics in the frozen phase.The existence of these large excitations brings about large fluctuations of the order parameter, and we have shown in these theses that this feature can be exploited to study the transition of any spin glass model. Moreover, we have shown that the information about these excitations can be extracted from the statistics of the lowest lying excitations. This is because due to the random nature of spin glasses, the physics obtained from averaging over the whole spectrum of excitations of an infinite sample is equivalent to averaging over many finite systems where only the ground state and the first excitation are considered. The novelty of this approach is that we do not need to make any assumption on what are typical excitations like because we can compute them exactly using numerical methods. Finally, we have investigated the dynamics and more specifically the link between the problem of chaos and the rejuvenation phenomena observed experimentally. Rejuvenation means that when lowering the temperature the aging process restarts again from scratch. This is potentially linked with the chaos assumption which states that equilibrium configurations at two different properties are not correlated. Chaos is a large scale phenomenon possible if entropy fluctuations are large. However, in this thesis we have shown that the response to temperature changes can be large in the absence of chaos close to a localization transition where the Boltzmann weight condenses in a few states. This has been observed in simulation of the Sinai model in which this localization is realized dynamically. In this model, since at low temperatures the system gets trapped in the very deep states, the dynamics is only local, so that only small excitations contribute to the rejuvenation signal that we have been able to observe. Thus, in agreement with the hierarchical picture, rejuvenation is possible even in the absence of chaos and reflects the start of the aging process of small length scales.
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Kern, Lydia. "Disordered eating among high school athletes." Connect to resource, 2010. http://hdl.handle.net/1811/45039.
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Castellana, Michele. "The renormalization group for disordered systems." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00694469.
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In this thesis we investigate the employ of the renormalization group for glassy systems. More precisely, we focus on models of spin glasses and structural glasses. Spin-glass models represent disordered uniaxial magnetic materials, such as a dilute solution of Mn in Cu, modeled by an array of spins on the Mn arranged at random in the matrix of Cu, and interacting with a potential which oscillates as a function of the separation of the spins. Structural glasses are liquids that have been cooled fast enough to avoid crystallization, like o-Terphenyl or Glycerol. Spin and structural glasses are physically interesting because their critical properties are known only in the limit where the space dimensionality tends to infinity, i. e. in the mean-field approximation. A fundamental question is whether the physical properties characterizing these systems in the mean-field case still hold for real spin or structural glasses, which live in a space with a finite number of dimensions. The spin and structural glasses that we study in this thesis are models built up on hierarchical lattices, which are the simplest non-mean field systems where the renormalisation group approach can be implemented in a natural way. The features emerging from this implementation clarify the critical behavior of these systems. As far as the finite-dimensional spin glass studied in this thesis is concerned, we developed a new technique to implement the renormalization group transformation for finite-dimensional spin glasses. This technique shows that the system has a finite-temperature phase transition characterized by a critical point where the system's correlation length is infinite. As far as the structural glass studied in this thesis is concerned, this is the first structural glass model where we showed the existence of a phase transition beyond mean field. The ideas introduced in this work can be further developed in order to understand the structure of the low-temperature phase of these systems, and in order to establish whether the properties of the low-temperature phase holding in the mean-field case still hold for finite-dimensional glassy systems.
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Mulansky, Mario. "Localization properties of nonlinear disordered lattices." Master's thesis, Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/3146/.
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In this thesis, the properties of nonlinear disordered one dimensional lattices is investigated. Part I gives an introduction to the phenomenon of Anderson Localization, the Discrete Nonlinear Schroedinger Equation and its properties as well as the generalization of this model by introducing the nonlinear index α.
In Part II, the spreading behavior of initially localized states in large, disordered chains due to nonlinearity is studied. Therefore, different methods to measure localization are discussed and the structural entropy as a measure for the peak structure of probability distributions is introduced. Finally, the spreading exponent for several nonlinear indices is determined
numerically and compared with analytical approximations.
Part III deals with the thermalization in short disordered chains. First, the term thermalization and its application to the system in use is explained. Then, results of numerical simulations on this topic are presented where the focus lies especially on the energy dependence of the thermalization properties. A connection with so-called breathers is drawn.In dieser Arbeit wird das Verhalten nichtlinearer Ketten mit Zufallspotential untersucht. Teil I enthaelt eine Einfuehrung in das Phaenomen der Anderson Lokalisierung, die Diskrete Nichtlineare Schroedinger Gleichung und ihren Eigenschaften sowie die verwendete Verallgemeinerung des Modells durch Einfuehrung eines Nichtlinearitaets-Indizes α. In Teil II wird das Ausbreitungsverhalten von lokalisierten Zustaenden in langen, ungeordneten Ketten durch die Nichtlinearitaet untersucht. Dazu werden zuerst verschiedene Lokalisierungsmaße besprochen und außerdem die strukturelle Entropie als Messgroeße der Peakstruktur eingefuehrt. Im Anschluss wird der Ausbreitungskoeffzient fuer verschiedene Nichtlinearitaets-Indizes bestimmt und mit analytischen Absch¨tzungen verglichen. Teil III behandelt schließlich die Thermalisierung in kurzen, ungeordneten Ketten. Dabei wird zuerst der Begriff Thermalisierung in dem verwendeten Zusammenhang erklaert. Danach erfolgt eine numerische Analyse von Thermalisierungseigenschaften lokalisierter Anfangszustaende, wobei die Energieabhaengigkeit besondere Beachtung genießt. Eine Verbindung mit sogenannten Breathers wird dargelegt.
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Dunkley, Cara R. "Disordered eating and sexuality in women." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54755.
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Background: There has long been a proposed clinical link between sexuality and eating disorders; however, little empirical evidence exists regarding this relationship. The limited body of research on sexuality in eating disorders supports the occurrence of considerable sexual concerns. The aim of the present study was to expand on the dearth of empirical literature exploring altered sexuality in relation to disordered eating. Study 1 examines disordered eating in relation to sexual function and sexual insecurities. Study 2 examines the association between eating disorder symptoms in relation to genital pain and sexual distress. Study 3 examines the mediational role of personality and mood on the relation between eating pathology and genital pain. Methods: Undergraduate female UBC students completed a series of online questionnaires assessing eating habits, sexual functioning, sexual insecurities, personality, and mood. Two rounds of data collection were conducted, the first occurring from December of 2013 to April of 2014 (n = 321), the second between May of 2014 and April of 2015 (n = 854). Results: Several domains of sexual dysfunction were associated with disordered eating symptom severity, particularly genital pain and sexual distress. Mean differences in eating disorder symptoms emerged in women with clinically significant genital pain compared to those without pain, such that women in the genital pain group reported more eating pathology. Mean differences in genital pain, sexual distress, and sexual insecurities emerged among women categorized as being at elevated, typical, or low eating disorder risk, with those at greater risk reporting greater sexual difficulties. Sexual insecurity variables, as well as personality and characteristics common to individuals with eating disorder pathology, mediated the association between disordered eating and genital pain. Discussion: Sexuality is rarely considered in the context of eating disorder treatment unless a history of sexual abuse is present. The results of this study suggest that sexual functioning difficulties should be addressed during eating disorder care. Findings also indicate that women with eating disorders would benefit from treatments targeting sexual insecurities and personality gestures associated with eating pathology in addition to sexual function.Arts, Faculty of
Psychology, Department of
Graduate
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Alpan, Ali. "Objective assessment of disordered connected speech." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209758.
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Within the context of the assessment of laryngeal function, acoustic analysis has an important place because the speech signal may be recorded non-invasively and it forms the base on which the perceptual assessment of voice is founded. Given the limitations of perceptual ratings, one has investigated vocal cues of disordered voices that are clinically relevant, summarize properties of speech signals and report on a speaker's phonation in general and voice in particular. Ideally, the acoustic descriptors should also be correlates of auditory-perceptual ratings of voice. Generally speaking, the goal of acoustic analysis is to document quantitatively the degree of severity of a voice disorder and monitor the evolution of the voice of dysphonic speakers.The first part of this thesis is devoted to the analysis of disordered connected speech. The aim is to investigate vocal cues that are clinically relevant and correlated with auditory-perceptual ratings. Two approaches are investigated. The variogram-based method in the temporal domain is addressed first. The second approach is in the cepstral domain. In particular, the first rahmonic amplitude is used as an acoustic cue to describe voice quality. A multi-dimensional approach combining temporal and spectral aspects is also investigated. The goal is to check whether acoustic cues in both domains report complementary information when predicting perceptual scores.
Both methods are tested first on a corpus of synthetic sound stimuli that has been obtained by means of a synthesizer of disordered voices. The purpose is to learn about the link between the signal properties (fixed by the synthesis parameters) and acoustic cues.
In this study, we had the opportunity to use two large natural speech corpora. One of them has been perceptually rated.
The final part of the text is devoted to the automatic classification of voice with regard to perceived voice quality. Many studies have proposed a binary (normal/pathological) classification of voice samples. An automatic categorization according to perceived degrees of hoarseness appears, however, to be more attractive to both clinicians and technologists and more likely to be clinically relevant. Indeed, one way to reduce inter-rater variability of an auditory-perceptual evaluation is to ask several experts to participate and then to average the perceptual scores. However, auditory-perceptual evaluation of a corpus by several judges is a very laborious, time-consuming and costly task. Making this perceptual evaluation task automatic is therefore desirable.
The aim of this study is to exploit the support vector machine classifier that has become, over the last years, a popular tool for classification, to carry out categorization of voices according to perceived degrees of hoarseness.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Chen, Leiming. "Tilt phase transitions in disordered systems /." view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1251884301&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2006.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 126-128). Also available for download via the World Wide Web; free to University of Oregon users.
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Bush, Ian J. "The electronic structure of disordered materials." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334224.
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Papathomas, Anthony. "Disordered Eating in Sport : Narrative's Turn." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/9084.
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A growing body of evidence suggests that athletes are at increased risk of disordered eating and eating disorders. The principal explanation proffers that extreme pressure to lose weight for performance gains can encourage the development of pathological attitudes and behaviours with regards to food and weight. The current consensus is that elite female athletes participating in sports with a focus on leanness or aesthetics are at greatest risk. This existing knowledge has emerged from a literature base characterised by a narrow focus on prevalence rates and risk factor identification. As a consequence, there are few examples of studies that address disordered eating in sport interpretively and we know little about how athletes experience the illness. The overarching aim of this thesis therefore, was to interpretively explore athletes subjective accounts of their disordered eating experiences, adding new, alternative insights that compliment the existing literature. In Study 1 I adopted an interpretative phenomenological analysis as a means to give voice to four athletes who have experienced disordered eating. The aim of this study was to document athletes personal accounts and to interpret these accounts from a psychological perspective. In-depth, semi-structured interviews were conducted and verbatim transcripts were analysed according to the procedures of IPA. Three superordinate themes emerged from the data: the struggle to disclose, social support needs, and identity challenges. Athletes stories provided rich descriptions of their subjective disordered eating experiences. Their accounts give critical insight into the impact of eating disturbance on the lives of athletes. In Study 2 I drew on narrative theory to interpretively analyse the life-story of Holly, a female athlete who engages in severe self-starvation. The broad aim here was to build on the interpretive insights gleaned in Study 1 and provide a detailed, qualitative exemplar of an athlete s life with disordered eating. More specifically, this study sought to explore the narrative processes by which an athlete comes to understand disordered eating and the impact this holds for experience. More than 7 hours of life history data was gathered over a period of 8 months through unstructured interviews. Holly described a struggle to align her life experiences with a culturally specified achievement narrative that lauds normative success. When neither her academic nor sporting endeavours fulfilled the achievement narrative, Holly was thrust into emotional turmoil and began to conceive of self-starvation as a means to achieve. Holly s narrative is in many ways fractured and void of the coherence necessary to move on from her troubles. It is argued that narrative realignment and coherence might be encouraged through narrative therapy. For Study 3, I sought to add a further detailed exemplar to the disordered eating in sport research base. Again building on the initial insights of Study 1, extended life-history data provided scope to delve into the deep complexities and pertinent ambiguities that characterise lived experiences. In applying principles of narrative analysis to this data, the objective was to provide further details as to how a disordered eating athlete makes sense of illness and the implications of this meaning making for future experiences. To achieve this I explored the stories of Beth, a former elite athlete with experience of anorexia nervosa and, as she revealed, sexual abuse. Six unstructured life history interviews took place over a period of 12 months yielding more than 9 hours of interview data. Due to a lack of previous narrative opportunities, the story Beth told was in many ways embryonic. Throughout our conversations Beth constructed multiple, fragile and sometimes contrasting narrative coherences indicative of a fragmented and uncertain understanding of her life. Beth s atypical story helps create a more complete understanding of eating disorders in sport and serves as an additional narrative resource from which others might draw to story experience. With Study 4 I sought to address the lack of family involvement in disordered eating in sport research. Given it is widely accepted that families are important in the management and treatment of eating disorders, I explore the experiences of an elite athlete with an eating disorder as well as the experiences of her parents. The underlying aim here was to explore the impact of athlete disordered eating on participants, both individually and as a family. Family members attended interviews individually on 3 separate occasions over the course of a year. Analysis involved repeated readings of the transcripts, sensitising towards issues of narrative content and structure. Participants interpreted the eating disorder through specific narrative types which shaped their experiences and guided their actions. Difficulties arose when personal experiences strayed from the preferred narrative to live by and when family members held contrasting narrative preferences. Suggestions are forwarded as to how an appreciation of eating disorder illness narratives might inform treatment and support practices. In conclusion, this thesis has demonstrated that it is insufficient to study disordered eating through solely positivist means. It is only through consistent, focused, interpretive study that a fuller, more complete, understanding of the illness can be achieved. Specifically, we must begin to add experiential insights to the medical preoccupation with nosology and symptomatology. This thesis has taken a significant step towards adding such insights. When invited to recount their experiences, athletes provide rich, powerful, subjective accounts that enable us to see disordered eating in sport through a new lens. The way athletes make sense of illness is sometimes ambiguous and contradictory, often complex and transient and always consequential for future experiences. Essentially, the narratives used to describe disordered eating impact on how disordered eating is lived through. As such, future research must explore the potential of narrative therapy to ease future disordered eating experiences, while also continuing to add to the critical mass of interpretive studies available.
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Horrigan, Emma. "Disordered microstructures and anomalous mechanical properties." Thesis, University of Exeter, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496775.
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This study concerns the effects of structural heterogeneity upon mechanical properties, particularly on negative Poisson's ratio. Two separate methods were used to generate two-dimensional honeycombs optimised for a series of material properties, in particular large negative Poisson's ratio and high stiffness. The properties and heterogeneity of crumpled and recycled materials were compared.