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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
901

Adaptation Cognitive et Vieillissement : entre Automatisme et Flexibilité / Cognitive Adaptation and Aging : between Automaticity and Flexibility

Tournier, Isabelle 13 December 2010 (has links)
L’objectif général de cette thèse est d’étudier l’évolution au cours du vieillissement des processus automatiques et contrôlés, nécessaires à une bonne adaptation cognitive quotidienne. Nous nous intéressons à l’influence de différentes variables cognitives (mémoire de travail, vitesse de traitement et vocabulaire) ainsi qu’aux préférences de routinisation sur l’expression de ce possible effet de l’âge. Des épreuves de fluidités sémantiques simples (Expérience 1) et alternées (Expérience 2 et 3) et des formats simples (Expérience 5a et 6a) et alternés (Expérience 5b et 6b) de la tâche de Hayling ont été réalisés par des adultes jeunes (18-30 ans), âgés (60-74 ans) et très âgés (75 ans et plus). Ces épreuves nous permettent d’étudier le processus automatique à travers la diffusion de l’activation en mémoire sémantique et les processus contrôlés par le biais de l’inhibition et de la flexibilité. L’activité cérébrale associée à l’exécution de fluidités simples et alternées est étudiée chez des participants âgés à l’aide de l’imagerie optique (Expérience 4). Les résultats obtenus sont en faveur d’une réduction avec l’âge de l’efficience des processus contrôlés alors que celle des processus automatiques semble conservée. Des phénomènes de compensation se mettraient en place au cours du vieillissement, s’appuyant sur les processus automatiques et les connaissances accumulées. / The aim of this thesis is to investigate the changes in automatic and controlled processes during aging which are necessary for satisfactory daily cognitive adaptation. The focus is the impact of various cognitive variables (i.e., working memory, speed of processing and vocabulary) and preferences for routines on the expression of this possible age effect. Simple (Experiment 1) and alternating fluency tasks (Experiments 2 and 3) as well as a simple (Experiments 5a and 6a) and alternating version of the Hayling task (Experiments 5b and 6b) were administered to young adults (18-30 years old), older adults (60-74 years old) and older-old adults (75 years old and over). These tasks allowed the study of automatic processes through spreading activation in semantic memory and of controlled processes through inhibition and flexibility. The cerebral activity associated with simple and alternating fluency task execution was investigated in elderly adults with near-infrared spectroscopy (Experiment 4). The results suggest a decrease with age in the efficiency of controlled processes whereas the efficiency of automatic processes seems to be preserved. Thus, compensation based on automatic processes and accumulated knowledge may appear during aging.
902

Kupní rozhodování na trhu kolových nápojů v ČR / The purchase decision on cole beverage market in Czech republic

Nováčková, Aneta January 2011 (has links)
The aim of my thesis was to analyze consumer behavior on cole beverage market in Czech republic. I focused my research mainly on students of University of Economics in Prague. To implement it I used a questionnaire survey and data analysis Market & Media & Lifestyle of MEDIAN agency. The thesis is divided into two parts - theoretical and methodological and analytical. The content of theoretical and methodological part is the definition of basic concepts such as consumer behavior, decision-making process, its types, factors and models, market research, data analysis. Characteristics of companies, the establishment of hypotheses, the research itself, its evaluation and recommendations are included in the analytical part.
903

Une approche d'aide multicritère à la décision pour l'évaluation du confort dans les trains : construction d'un modèle d'évaluation / A multiple criteria decision aiding tool for evaluating the overall comfort on board trains

Mammeri, Mohamed 17 September 2013 (has links)
Les travaux de recherche menés dans cette thèse s’inscrivent dans deux champs disciplinaires que sont l’évaluation du confort et l’aide multicritère à la décision.L’objectif de la thèse est de construire un modèle pour évaluer des trains sur le point de vue du confort tel qu’il est perçu par les voyageurs. L’approche utilisée pour cela repose sur trois étapes principales de construction d’un modèle d’aide multicritère à la décision. La première consiste à définir et à formaliser les critères de confort du problème. Dans la deuxième étape, il s’agit de construire les échelles afin de pouvoir évaluer les trains sur chaque critère de confort considéré.La troisième étape consiste à agréger les critères de confort en utilisant des méthodes d’agrégation multicritère. Cette étape nécessite l’élicitation des préférences des décideurs afin de mettre en oeuvre les méthodes d’agrégation.Notre contribution est de formaliser une approche pour la construction d’un modèle d’évaluation du confort dans les trains. Cette approche peut être appliquée à d’autres problématiques que l’évaluation du confort. Elle présente deux particularités principales. La première est d’intégrer dans la construction du modèle des facteurs importants traduisant la perception du confort. Nous avons choisi pour cela un modèle hiérarchique comportant plusieurs niveaux. La deuxième particularité de l’approche est d’utiliser des méthodes d’agrégation pouvant être différentes d’un noeud à un autre du modèle. Elle présente également d’autres aspects plus spécifiques, notamment lors de l’élicitation des préférences où nous construisons des exemples d’apprentissage informatifs pour accélérer le processus d’élicitation / This PhD thesis falls within two scientific areas, which are comfort evaluation and multiple criteria decision aiding. The main purpose is to develop a model in order to evaluate trains on the comfort point of view, as percieved by passengers. The developed approach is based on three main steps of developing a multiple criteria decision aiding model. The first one consists on defining and formalizing the criteria of comfort. In the second step, the scales of each considered criterion must be built in order to evaluate the trains on these last. The third step aims at aggregating the criteria, using multiple criteria aggregation methods, in order to obtain an overall comfort evaluation of trains. For this purpose, the decision maker’s preferences must be elicited
904

A relação entre o bullying e os relacionamentos sociais num grupo de adolescentes brasileiros / Not informed by the author

Lina Marcela Pedraza Torres 02 October 2017 (has links)
Na questão do bullying, um subtipo de agressão frequente nas escolas, aspectos ligado à organização social do grupo são de importância na compreensão do fenômeno. No presente estudo, avaliamos a correlação entre o bullying/vitimização e as variáveis de popularidade percebida, preferência social e impacto social, num grupo de adolescentes entre 12 e 14 anos na cidade de São Paulo, Brasil. Para avaliação do bullying e da vitimização utilizamos o questionário Peer Assessment e, para avaliar o status social e a popularidade percebida, usamos dois testes sociométricos, cada um com duas perguntas. Verificamos a interação entre as variáveis e os efeitos principais com o uso de Equações de Estimação (GEE) com efeito aleatório. Os resultados mostraram que os adolescentes menos gostados têm mais chance de ser vitimizados, e os mais populares, de serem agressores. Além disso, há correlação direta entre a agressividade e o impacto social de cada um (o quanto é lembrado pelos pares), e há uma relação inversa entre agressividade e preferência social. / Social organization of the group is an important aspect involved in bullying, a frequent type of aggression found in schools. In this study, we present the correlation between bullying / victimization and variables of perceived popularity, social preference and social impact in a group of adolescents between 12 and 14 years old in the city of São Paulo, Brazil. Bullying and Victimization were assessed through the Peer Assessment questionnaire and, Social Status and Perceived Popularity were assessed through two sociometric tests, each one with two questions. We used generalized linear model (GEE) to check the interaction between the variables. According to our results, the less liked the more victimized an adolescent will be, and the more popular the higher the chance of being aggressor. In addition, there is a direct correlation between aggressiveness and the social impact of each one (how much the person is remembered by the peers), and there is an inverse relationship between aggressiveness and social preference.
905

Desenvolvimento de microemulsões e sua transformação in situ em géis de fase líquido-cristalina como plataforma para liberação sustentada de fármacos e seu uso no tratamento do alcoolismo. / Development of microemulsions and their in situ transformation in liquid-crystalline phase gels as a platform for sustained release of drugs and their use in the treatment of alcoholism.

Santos, Rogério Aparecido dos 06 December 2017 (has links)
Este estudo visa o desenvolvimento de microemulsões que, após captação de água do tecido subcutâneo, transformar-se-ão em gel nanoestruturado de fase hexagonal para liberação sustentada de naltrexona e tratamento do alcoolismo. A microemulsão selecionada, composta por monooleína, tricaprilina, propilenoglicol e água (ME-MO) resultou na liberação in vitro de 31 % de naltrexona em 96 h. Após sua administração subcutânea, foi observada formação do gel em 48 h, o qual persistiu por mais de 30 dias in vivo, promovendo liberação prolongada do marcador fluorescente Alexa flúor. A eficácia da formulação foi avaliada em modelo de preferência condicionada por lugar induzida por etanol; ME-MO com 5 e 10% de naltrexona foi comparada à solução de naltrexona diária. Não observou-se diferença significativa entre a solução de naltrexona e ME-MO 5%, enquanto que ME-MO 10% diferiu destas, e antagonizou a preferência condicionada por lugar. Esses resultados demonstram o potencial de ME-MO como uma plataforma para liberação prolongada de fármacos no tratamento de dependência química. / This study focuses on the development of microemulsions that after in vivo water uptake of the subcutaneous tissue will turn into liquid-crystalline gels for sustained release of naltrexone, used in the treatment of alcoholism. Three microemulsions based on monoolein and tricapryline (ME-MO), vitamin E TPGS and propylene glycol, TPGS and Span were selected. The latter resulted is faster drug release (65% in 96 h). Based on the ability of the gel formed to withstand dilution, ME-MO was selected for in vivo studies. After subcutaneous administration, hexagonal phase formation was observed in 48 h and its persistence for more than 30 days in those animals. The efficacy of the formulation was assessed using conditioned preference place model. The animals were divided into four groups: Saline (control); Naltrexone solution (1 mg / kg) daily for 8 days (30 min before ethanol administration), and ME-MO with 5% or 10% naltrexone (single administration). The results suggest that ME-MO 10% antagonized the preference induced by ethanol.
906

An Analysis of the Interaction of Methylphenidate and Nicotine in Adolescent Rats: Effects on BDNF

Freeman, Elizabeth D 01 August 2015 (has links)
This investigation was an analysis of the interaction of adolescent exposure to methylphenidate (MPH; trade name: Ritalin) on nicotine sensitization and conditioned place preference (CPP) in a rodent model and underlying mechanisms of this effect. Animals were treated IP with 1 mg/kg MPH or saline using a ―school day‖ regimen of five days on, two days off, from postnatal day (P) 28-50. During the final two weeks of MPH treatment, animals were either behaviorally sensitized to nicotine (0.5 mg/kg free base) or saline for 10 days, or conditioned to nicotine or saline using the CPP behavioral paradigm. In addition, three days after behavioral sensitization was complete, animals were analyzed for stress behavior using the forced swim stress behavioral test. In addition, 24 hours after post-test conditioning animals were analyzed for the effect of a clinically relevant dose of pre-exposed MPH (1mg/kg) and nicotine treatment on the expression of BDNF in the nucleus accumbens and dorsal hippocampus. Behavioral results revealed that adolescent pre-exposure to MPH blunted nicotine behavioral sensitization in both male and female rats during the first week of testing. However, MPH enhanced nicotine CPP in both adolescent male and female rats. Interesting, animals administered MPH demonstrated a significantly decreased latency to immobility in the forced swim stress behavioral test. In addition, pre-exposure to a 1 mg/kg dose of MPH appears to have sensitized the BDNF response to nicotine in females as compared to all other groups.
907

Computer simulations exploring conformational preferences of short peptides and developing a bacterial chromosome model

Li, Shuxiang 15 December 2017 (has links)
Computer simulations provide a potentially powerful complement to conventional experimental techniques in elucidating the structures, dynamics and interactions of macromolecules. In this thesis, I present three applications of computer simulations to investigate important biomolecules with sizes ranging from two-residue peptides, to proteins, and to whole chromosome structures. First, I describe the results of 441 independent explicit-solvent molecular dynamics (MD) simulations of all possible two-residue peptides that contain the 20 standard amino acids with neutral and protonated histidine. 3JHNHα coupling constants and δHα chemical shifts calculated from the MD simulations correlated quite well with recently published experimental measurements for a corresponding set of two-residue peptides. Neighboring residue effects (NREs) on the average 3JHNHα and δHα values of adjacent residues were also reasonably well reproduced. The intrinsic conformational preferences of each residue, and their NREs on the conformational preferences of adjacent residues, were analyzed. Finally, these NREs were compared with corresponding effects observed in a coil library and the average β-turn preferences of all residue types were determined. Second, I compare the abilities of three derivatives of the Amber ff99SB force field to reproduce a recent report of 3JHNHα scalar coupling constants for hundreds of two-residue peptides. All-atom MD simulations of 256 two-residue peptides were performed and the results showed that a recently-developed force field (RSFF2) produced a dramatic improvement in the agreement with experimental 3JHNHα coupling constants. I further show that RSFF2 also improved modestly agreement with experimental 3JHNHα coupling constants of five model proteins. However, an analysis of NREs on the 3JHNHα coupling constants of the two-residue peptides indicated little difference between the force fields’ abilities to reproduce experimental NREs. I speculate that this might indicate limitations in the force fields’ descriptions of nonbonded interactions between adjacent side chains or with terminal capping groups. Finally, coarse-grained (CG) models and multi-scale modeling methods are used to develop structural models of entire E. coli chromosomes confined within the experimentally-determined volume of the nucleoid. The final resolution of the chromosome structures built here was one-nucleotide-per-bead (1 NTB), which represents a significant increase in resolution relative to previously published CG chromosome models, in which one bead corresponds to hundreds or even thousands of basepairs. Based on the high-resolution final 1 NTB structures, important physical properties such as major and minor groove widths, distributions of local DNA bending angles, and topological parameters (Linking Number (Lk), Twist (Tw) and Writhe (Wr)) were accurately computed and compared with experimental measurements or predictions from a worm-like chain (WLC) model. All these analyses indicated that the chromosome models built in this study are reasonable at a microscopic level. This chromosome model provides a significant step toward the goal of building a whole-cell model of a bacterial cell.
908

TOWARDS A HEALTHIER CHOCOLATE FORMULA WHICH IS RICH IN POLYPHENOLS AND LOW IN FAT

Galaniha, Lakmani Tharaka 01 January 2018 (has links)
Chocolate is a food that is craved by many in the world and healthy chocolates have become a current topic in the healthy eating trend. The healthiness of a chocolate depends mainly on the polyphenol, fat and sugar contents. Although the literature serves several interventions to reduce the fat content and total calorie content of chocolates, it does not provide many interventions that consider both improving the polyphenol and reducing the fat content simultaneously. Considering this gap in the literature, this research project sought to develop a chocolate that is both low in fat and high in polyphenol content, without sacrificing the taste that consumers would expect in a good dark chocolate. The research resulted in three chocolate formulas that consists of 60% cocoa and 30% fat (formula A, formula B and formula C). They differed from each other in the polyphenol content due to the changes in the cocoa powder type and the presence or absence of freeze-dried blueberry powder. Formula A and formula B mainly differed in the percentage of each type of cocoa powder, both alkalized and non- alkalized. Formula C differed from the other two formulas because there was no freeze-dried blueberry powder. The resulted chocolates were evaluated for the sensory characteristics using paired preference tests and consumer-oriented attribute diagnostic tests (color, flavor, melting properties, overall preference, likelihood to buy). They were analyzed for polyphenol content using Folin-Ciocalteu assay. The chocolates were compared with a well-established commercial chocolate (formula D) of a 60% cocoa. Sensory evaluation tests revealed that formula C was superior and comparable to the commercial chocolate D in all the tested attributes except for color. Polyphenol analysis confirmed that all three developed formulas had a higher polyphenol estimate than formula D. Consumers preferred to buy each chocolate type regardless of the differences in their preference for the other attributes, if the chocolates were known to be healthier. Formula C was found to be the best prototype formula among the developed formulas and it can further be developed to enhance the color and other attributes in future work.
909

Behavioral Operations Management in Federal Governance

Mobley, Frederick Leonard 01 January 2015 (has links)
The environmental uncertainty of federal politics and acquisition outsourcing in competitive markets requires an adaptive decision-analysis structure. Practitioners oriented toward exclusively static methods face severe challenges in understanding qualitative aspects of organizational governance. The purpose of this grounded theory study was to examine and understand behavioral relationship attributes within intuitive, choice, judgment, or preference decision-making processes. The problem addressed in this study was the detrimental effects of organizational citizenship behavior (OCB), compulsory citizenship behavior (CCB), and social exchange theory (SET) on the acquisition management relationship The OCB, CCB, SET dictates that sound business development, relationship acumen, emotional intelligence and perceptiveness transcend pure numerical quantification. Exhibition of relationship-based attributes influence and drive long-term contractual relationships and the sustainability of business organizations. The data collected included historical data and survey responses. Approximately 34,000 acquisition professionals comprised the population-sampling frame. The study sample consisted of 378 survey responses that yielded 294 qualifying respondents with 94 disqualifications that produced a 78% response rate. The Carnegie-Mellon behavioral survey guidelines underpinned questionnaire construction and affirmation of themes. Strauss and Corbin grounded theory and theme generation addressed behavioral decision making under the additive model that inform the development of an organizational social operations and business framework that accounts for intuitive judgment. The study may contribute to positive social change by orienting managers toward behavioral decision making, ensuring responsiveness to the public and federal governance
910

Preference, Resistance to Change, and Qualitatively Different Reinforcers

Podlesnik, Christopher Aaron 01 May 2008 (has links)
Preference for one stimulus context over another and resistance to disruption within those contexts are a function of the conditions of reinforcement arranged within those contexts. According to behavioral momentum theory, these measures are converging expressions of the concept of response strength. Most studies have found that preference in concurrent chains and resistance to change are greater in contexts presenting higher rates or larger magnitudes of reinforcement. The present series of experiments attempted to extend behavioral momentum theory by examining whether differences in reinforcer type affect relative response strength with rats lever pressing for different types of food. In Experiment 1 of Chapter 2, several nonuniform disrupter types were examined that provided free access to a food type that was the same as one reinforcer type. Responding decreased more in the context presenting the same type of reinforcer as the disrupter, suggesting that many traditional disrupters (e.g., satiation) are inappropriate for examining how reinforcer type impacts response strength. Therefore, extinction was used throughout the remainder of the experiments to more uniformly disrupt responding across contexts. In Experiment 2 of Chapter 2, resistance to extinction was assessed when food pellets and a sucrose solution maintained responding across contexts. Moreover, relative reinforcer type was manipulated by changing the sucrose concentration across conditions. Relative response rates were systematically affected by changing sucrose concentration, but relative resistance to extinction was not. In Experiment 3 of Chapter 2, qualitative difference between reinforcers was enhanced and preference also was assessed to provide a converging measure of response strength. Preference and relative response rates were systematically affected, but relative resistance to extinction again was not. Finally, in Chapter 3, relative reinforcer rate and type were manipulated while assessing preference and resistance to extinction using the matching law. Preference, but not resistance to extinction, consistently was affected by changes in reinforcer rate and type. Systematic deviations in sensitivity and bias, however, suggested that different reinforcer types interacted with reinforcer rate. Overall, these findings suggest that the overall context of reinforcement, including interactions between different reinforcer types, should be considered when assessing preference and relative resistance to change.

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