Citizen participation includes those activities by citizens who are not public officials that are more or less intended to influence the actions taken by government (Verba & Nie, 1972). Citizen initiated contacts are one such form of participation. In 1999, the volume of complaint and service related calls received by the Department of Public Works and Engineering equaled almost 20 percent of the city's population. Via Houston's Customer Response Center, these contacts are logged in, directed to the appropriate department and incorporated into the department's infrastructure management system (IMS). The goal of the IMS is to provide a systems approach to making cost-effective decisions about the design, rehabilitation, construction, retrofitting, maintenance or abandonment of the city's infrastructure (Grigg, 1988). To date, the effectiveness of this program is perceived as less than ideal and the public is critical of the results (Graves, 2002). Residents express concerns that infrastructure projects are targeted towards business and industrial areas while neighborhood needs are being ignored. Politicians are concerned that projects are not equally distributed among the districts. Meanwhile, public works' staff are concerned because there isn't enough money to address citizen calls, business and industrial needs and political concerns in addition to the problems they have identified. The purpose of this research is twofold: to determine if citizen initiated contacts have been a significant factor in the selection of water and sewer projects and, to identify other factors that may play a role in the decision making process. This study is longitudinal in nature, covering the time period between 1992 and 1999. Univariate, bivariate and multivariate analysis were applied to the various data sets provided by the City of Houston. The results of the analysis supports the following: - Citizen contacts have been significant in determining the allocation of water and sewer CIP projects; however, that has not been consistent through the years. - Factors such as race, class, line type, material, size, age and location also factor into the decision making process.

Dans une automobile, les composants électriques sont alimentés par un type de générateur électrique particulier : l'Alternateur. Entraîné par le moteur du véhicule, il lui prélève donc de la puissance mécanique. Dans les périodes de chasse au gramme de CO2 que nous connaissons, la puissance prélevée au moteur doit être minimisée pour ne pas pénaliser sa consommation. Or les besoins électriques du réseau de bord et des systèmes (éclairage, ventilation, servitudes, contrôle moteur, etc.) sont imposés par l'équipement du véhicule. Il est apparu que dans les cas où l'alternateur est fortement sollicité, des pertes de performances peuvent être imputées au circuit d'excitation de la machine. Il comporte deux contacts électriques glissants balai-bague qui ont été incriminés. Du point de vue théorique aucun élément ne permettait d'expliquer les augmentations brutales de résistance de ces contacts, nous avons donc développé une méthode de mesure originale destinée à rechercher des paramètres influents sur leurs variations. Il nous a été impossible de faire une mesure de l'épaisseur film de transfert et d'identifier les quantités de graphite, nature et quantité des oxydes en présence dans le film. Cependant, nous avons estimé la pertinence de l'hypothèse du rôle de l'oxydation et avons surtout pu isoler le rôle du film de transfert dans l'expression des résistances de contact. Nous avons, de plus, mis en évidence la corrélation existant entre les résistances de contact et le coefficient de frottement pour les deux contacts.

Les pieds d'aubes de soufflantes de turboréacteurs font face à des sollicitations de type fretting. Il en résulte deux types d'endommagements: (i) l'amorçage et la propagation de fissures, (ii) l'usure des surfaces en contact. OBJECTIF: Afin de fournir les outils permettant de répondre à la problématique industrielle, une méthode semi-analytique permettant de traiter des problèmes de contacts élasto-plastiques revêtus et/ou hétérogènes est développé à partir d'éléments existants et de solutions analytiques et numériques novatrices. METHODE: La structure est simplifiée en supposant un contact entre deux massifs élastiques semi-infinis. Des solutions analytiques donnant pour: + les contributions élémentaires de chargements normaux et tangentiels constants sur une surface rectangulaire + les contributions élémentaires de déformations plastiques supposées constantes sur un volume parallélépipédique + les contributions élémentaires de déformations d'incompatibilité liées à un problème hétérogène (inclusions, revêtements, endommagement,...) supposées constantes sur un volume parallélépipédique. >> les déplacements en surface ou les contraintes dans le volume. Les déplacements en surface ou les contraintes dans le volume sont alors exprimés en utilisant des produits de convolution discrets entre des coefficients d'influence et la source surfacique (chargements en surface) ou volumique (déformations plastiques ou d'incompatibilité). Le problème normal et le problème tangentiel en glissement total ou en glissement partiel peuvent alors être résolus, en prenant en compte les effets plastiques et hétérogènes. L'algorithme d'optimisation sous contrainte utilisé (contact elastique) est celui développé par L.Gallego tandis que la base du solver plastique utilisé a été développé par C. Jacq (contact elasto-plastique sans frottement) RESULTATS: De nouvelles solutions analytiques sont obtenues pour le calcul des déplacements résiduels tangentiels.

Les Méthodes par Eléments Discrets apparaissent comme les méthodes les plus appropriées pour modéliser le caractère divisé. De nombreux travaux ont permis de mieux comprendre leurs comportements, mais dans certain cas se pose la question de l'impact du choix de la description volumique ou des lois d'interaction sur le comportement global du milieu. Dans ce contexte, en se basant sur l'approche "Non Smooth Contact Dynamic" permettant naturellement de mixer les différentes formulations, nous nous proposons de comprendre et d'analyser l'influence de cette description. Pour cela, nous utilisons deux applications différentes liées aux comportement quasi-statique (QS) des milieux granulaires et comportement dynamique des interfaces tribologiques. Au niveau de l'étude QS est faite en utilisant des essais de compression biaxiale et de cisaillement. Contrairement aux approches classiques, des particules déformables sont utilisées ici. Les résultats obtenus sont comparés en utilisant des outils de mesure tels que la relation contrainte-déformation, la compacité... Les résultats montrent qu'il n'est pas possible à partir d'une description rigide de converger vers des modèles déformables et souligne l'importance d'effectuer une analyse complète en tenant compte de la déformation des particules. Au niveau de la modélisation d'une interface tribologique s'intéresse à l'influence des conditions limites, des descriptions des premiers corps et du troisième corps sur la rhéologie de l'interface. Dans chaque simulation, frottement macroscopique, profils de vitesse et de contrainte sont observés. Les différents modèles utilisés ont peu d'influence sur la valeur du frottement mais plus d'influence sur les profils de vitesse au travers de l'épaisseur de troisième corps. Ceci souligne l'importante du choix du modèle lors de l'étude de la rhéologie de l'interface et montre qu'il est difficile d'obtenir des résultats génériques et ceci aussi bien en modèles bi que tridimensionnel.

A self-terminated electrochemical method was used to fabricate microscopic-scale contacts between two Au electrodes in a microfluidic channel. The conductance of contacts varies in a stepwise fashion showing quantization near the integer multiples of the conductance quantum ( ). The mechanism works by a pressure-driven flow parallel to a pair of Au electrodes with a gap on the order of micron in an electrolyte of HCl. When applying a bias voltage between two electrodes, metal atoms are etched off the anode and dissolved into the electrolyte as metal ions, which are then deposited onto the cathode. Consequently, the gap decreases to the atomic scale and then completely closes as the two electrodes form a contact. The electrochemical fabrication approach introduces large variance in the formation and location of individual junctions. Understanding and controlling this process will enable the precise positioning of reproducible geometries into nano-electronic devices.

n-type binary compound semiconductors such as InN, InAs, or In2O3 are especial because the branch-point energy or charge neutrality level lies within the conduction band. Their tendency to form a surface electron accumulation layer prevents the formation of rectifying Schottky contacts. Utilizing a reactive sputtering process in an oxygen-containing atmosphere, we demonstrate Schottky barrier diodes on indium oxide thin films with rectifying properties being sufficient for space charge layer spectroscopy. Conventional non-reactive sputtering resulted in ohmic contacts. We compare the rectification of Pt, Pd, and Au Schottky contacts on In2O3 and discuss temperature-dependent current-voltage characteristics of Pt/In2O3 in detail. The results substantiate the picture of oxygen vacancies being the source of electrons accumulating at the surface, however, the position of the charge neutrality level and/or the prediction of Schottky barrier heights from it are questioned.

This thesis deals with electron correlation effects within low-dimensional, mesoscopic systems. We study phenomena within two different types of system in which correlations play an important role. The first involves the spectra and spin structure of small symmetric quantum dots, or &quoteartificial atoms&quote. The second is the &quote0.7 structure&quote, a well-known but mysterious anomalous conductance plateau which occurs in the conductance profile of a quantum point contact. Artificial atoms are manufactured mesoscopic devices: quantum dots which resemble real atoms in that their symmetry gives them a &quoteshell structure&quote. We examine two-dimensional circular artificial atoms numerically, using restricted and unrestricted Hartree-Fock simulation. We go beyond the mean-field approximation by direct calculation of second-order correlation terms; a method which works well for real atoms but to our knowledge has not been used before for quantum dots. We examine the spectra and spin structure of such dots and find, contrary to previous theoretical mean-field studies, that Hund's rule is not followed. We also find, in agreement with previous numerical studies, that the shell structure is fragile with respect to a simple elliptical deformation. The 0.7 structure appears in the conductance of a quantum point contact. The conductance through a ballistic quantum point contact is quantised in units of 2e^2/h. On the lowest conductance step, an anomalous narrow conductance plateau at about G = 0.7 x 2e^2/h is known to exist, which cannot be explained in the non-interacting picture. Based on suggestive numerical results, we model conductance through the lowest channel of a quantum point contact analytically. The model is based on the screening of the electron-electron interaction outside the QPC, and our observation that the wavefunctions at the Fermi level are peaked within the QPC. We use a kinetic equation approach, with perturbative account of electron-electron backscattering, to demonstrate that these simple features lead to the existence of a 0.7-like structure in the conductance. The behaviour of this structure reproduces experimentally observed features of the 0.7 structure, including the temperature dependence and the behaviour under applied in-plane magnetic fields.

Past research on the acceleration phase in sprint running has concentrated on the kinematics of sprint blocks set-up and the initial steps after exiting the sprint blocks. In contrast, there has been limited research on the ground reaction forces (GRF) generated during the initial post-block foot contacts. These initial foot contacts in sprinting are important for optimising performance in the initial acceleration phase of sprinting. However, little is known about the GRF elite sprinters generate during the initial foot contacts and how these GRF characteristics relate to performance. It is the anterior-posterior (A-P) GRF that are of most importance as they indicate the sprinter’s motion from the start to the finish line. This thesis investigates the A-P GRF of the first two foot contacts of the sprint start after leaving the blocks. The participants included seventeen male and six female sprinters with a mean age of 22.6 (SD 4.4 years). Seventeen of the sprinters had competed at international/national level competitions and six at recreational/amateur level competitions. The athletes were classified as senior male elite (SME), senior female elite (SFE), junior male elite (JME) and senior male recreational (SMR). The sprinters were instructed to perform block starts at maximal effort to produce the fastest time over 5 metres on a 30 metre indoor laboratory track. Timing gates were used to record 5 metre times and two strain gauge force plates were placed in series to collect GRF data from the first two foot contacts after leaving the starting blocks. From the GRF data, braking time, maximum A-P braking force, A-P braking impulse, propulsive time, maximum A-P propulsive force, A-P propulsive impulse and A-P contact impulse were determined for each trial. The A-P propulsive phase constituted greater than 90% of the total contact time, had approximately twice the magnitude of the maximum force of the braking phase and accounted for more than 95% of the total contact impulse across the four groups of sprinters. The SME group produced a significantly larger A-P propulsive impulse on the first and second steps compared to the SFE (p less than 0.05 and p less than 0.05 respectively), JME (not significant and p less than 0.05 respectively) and SMR (p less than 0.05 and p less than 0.05 respectively) groups. The SME group’s maximum A-P propulsive force was significantly larger on the first and second steps than the SFE (p less than 0.05 and p less than 0.05 respectively), JME (p less than 0.05 and p less than 0.05 respectively) and SMR (p less than 0.05 and p less than 0.05 respectively) groups. The SME group’s propulsive time on the first and second steps was not significantly different compared to the SFE (both not significant) but was significantly shorter compared to the JME (p less than 0.05 and p less than 0.05 respectively) and SMR (p less than 0.05 and p less than 0.05 respectively) groups. The maximum A-P propulsive force correlated strongly with 5 metre time for the first step (rs = -0.670, p less than 0.01), second step (rs = -0.621, p less than 0.01) and the addition of the first and second steps (rs = -0.678, p less than 0.01) across all the sprinters. Whereas, the A-P propulsive impulse correlated strongly with 5 metre time for the first step (rs = -0.525, p less than 0.01), second step (rs = -0.592, p less than 0.01) and the addition of the first and second steps (rs = -0.584, p less than 0.01). Three A-P GRF patterns were observed during the first and second foot contacts of the sprinters examined in this study. A braking-propulsive (B-P) pattern was the most frequently observed followed by a propulsive-braking-propulsive (P-B-P) and a no braking (NB) pattern 82.7%, 15.4% and 1.9% respectively. The P-B-P and NB patterns, which have not been described previously, appeared most frequently in the least experienced sprinters. In the past, some sprinters and their coaches have tried to minimise the braking phase and maximise the propulsive phase of the first two foot contacts after exiting the blocks during sprinting. This study suggests that increasing the maximum propulsive force is the best way to increase performance over the first 5 metres of the acceleration phase. The research also suggests that there will be little benefit gained from trying to increase performance by focusing on the braking phase during these first two steps after exiting the blocks. As such, sprinters and coaches should focus their attention primarily on producing a large A-P propulsive force during the first two steps of a sprint.

Past research on the acceleration phase in sprint running has concentrated on the kinematics of sprint blocks set-up and the initial steps after exiting the sprint blocks. In contrast, there has been limited research on the ground reaction forces (GRF) generated during the initial post-block foot contacts. These initial foot contacts in sprinting are important for optimising performance in the initial acceleration phase of sprinting. However, little is known about the GRF elite sprinters generate during the initial foot contacts and how these GRF characteristics relate to performance. It is the anterior-posterior (A-P) GRF that are of most importance as they indicate the sprinter’s motion from the start to the finish line. This thesis investigates the A-P GRF of the first two foot contacts of the sprint start after leaving the blocks. The participants included seventeen male and six female sprinters with a mean age of 22.6 (SD 4.4 years). Seventeen of the sprinters had competed at international/national level competitions and six at recreational/amateur level competitions. The athletes were classified as senior male elite (SME), senior female elite (SFE), junior male elite (JME) and senior male recreational (SMR). The sprinters were instructed to perform block starts at maximal effort to produce the fastest time over 5 metres on a 30 metre indoor laboratory track. Timing gates were used to record 5 metre times and two strain gauge force plates were placed in series to collect GRF data from the first two foot contacts after leaving the starting blocks. From the GRF data, braking time, maximum A-P braking force, A-P braking impulse, propulsive time, maximum A-P propulsive force, A-P propulsive impulse and A-P contact impulse were determined for each trial. The A-P propulsive phase constituted greater than 90% of the total contact time, had approximately twice the magnitude of the maximum force of the braking phase and accounted for more than 95% of the total contact impulse across the four groups of sprinters. The SME group produced a significantly larger A-P propulsive impulse on the first and second steps compared to the SFE (p less than 0.05 and p less than 0.05 respectively), JME (not significant and p less than 0.05 respectively) and SMR (p less than 0.05 and p less than 0.05 respectively) groups. The SME group’s maximum A-P propulsive force was significantly larger on the first and second steps than the SFE (p less than 0.05 and p less than 0.05 respectively), JME (p less than 0.05 and p less than 0.05 respectively) and SMR (p less than 0.05 and p less than 0.05 respectively) groups. The SME group’s propulsive time on the first and second steps was not significantly different compared to the SFE (both not significant) but was significantly shorter compared to the JME (p less than 0.05 and p less than 0.05 respectively) and SMR (p less than 0.05 and p less than 0.05 respectively) groups. The maximum A-P propulsive force correlated strongly with 5 metre time for the first step (rs = -0.670, p less than 0.01), second step (rs = -0.621, p less than 0.01) and the addition of the first and second steps (rs = -0.678, p less than 0.01) across all the sprinters. Whereas, the A-P propulsive impulse correlated strongly with 5 metre time for the first step (rs = -0.525, p less than 0.01), second step (rs = -0.592, p less than 0.01) and the addition of the first and second steps (rs = -0.584, p less than 0.01). Three A-P GRF patterns were observed during the first and second foot contacts of the sprinters examined in this study. A braking-propulsive (B-P) pattern was the most frequently observed followed by a propulsive-braking-propulsive (P-B-P) and a no braking (NB) pattern 82.7%, 15.4% and 1.9% respectively. The P-B-P and NB patterns, which have not been described previously, appeared most frequently in the least experienced sprinters. In the past, some sprinters and their coaches have tried to minimise the braking phase and maximise the propulsive phase of the first two foot contacts after exiting the blocks during sprinting. This study suggests that increasing the maximum propulsive force is the best way to increase performance over the first 5 metres of the acceleration phase. The research also suggests that there will be little benefit gained from trying to increase performance by focusing on the braking phase during these first two steps after exiting the blocks. As such, sprinters and coaches should focus their attention primarily on producing a large A-P propulsive force during the first two steps of a sprint.

Hanseníase é uma das mais antigas e instigantes doenças que acometem o ser humano. Ferramentas moleculares e imunológicas são avaliadas em diversos estudos epidemiológicos, porém com resultados controversos devido à alta complexidade da doença e metodologias utilizadas. Este estudo descreve o uso da sorologia anti PGL-I e da detecção de DNA em swab nasal para caracterizar a epidemiologia molecular do Mycobacterium leprae em pacientes e contatos domiciliares de pacientes com hanseníase. Em pacientes com hanseníase a positividade nos testes ELISA anti PGL-I e PCR para a detecção do DNA de M. leprae em swab nasal são inversamente associadas ao teste de Mitsuda e são diretamente associadas com o índice baciloscópico e as formas clínicas no espectro da doença, aumentando em direção às formas bacilíferas. As porcentagens gerais de positividade em pacientes foram 63,3% para o ELISA anti PGL-I e 34,2% para a PCR para detecção do DNA de M. leprae em swab nasal. Nos contatos domiciliares de pacientes com hanseníase as porcentagens gerais para o ELISA anti PGL-I e para a PCR para detecção do DNA de M. leprae em swab nasal foram 13,3% e 4,7% respectivamente. Os contatos com resultados positivos nestas metodologias representam portadores sadios ou com infecção subclínica e podem participar na transmissão e manutenção do M. leprae na comunidade, mesmo que os mesmos não venham a adoecer. É imperativo para o controle da hanseníase o monitoramento de contatos domiciliares em regiões endêmicas para detecção precoce de novos casos e a quimioprofilaxia deve ser utilizada como prevenção para o desenvolvimento da doença e interrupção da transmissão. / Leprosy is one of the oldest and most instigating diseases to affect humans. Molecular and immunological tools are evaluated in epidemiological studies; however, the results present controversies mainly due to disease complexity and methodologies. This study describes the application of anti PGL-I serology and nasal swab DNA detection to characterize Mycobacterium leprae molecular epidemiology in patients and household contacts of leprosy patients. Among leprosy patients the positivity to the anti PGL-I ELISA and the PCR for the detection of M. leprae DNA in nasal swabs are inversely associated to the lepromin test and arte directly associated to the bacillary index and the clinical forms in the disease spectrum, increasing towards baciliferous forms. The overall positivity percentages were 63.3% for the anti PGL-I ELISA and 34.2% for the PCR for the detection ofM. leprae DNA in nasal swabs. Among household contacts of leprosy patients the overall percentages for the anti PGL-I ELISA and for the PCR for the detection of M. leprae DNA in nasal swabs were 13.3% e 4.7% respectively. Among leprosy patients, assays positivity is associated with the clinical presentation of the disease, increasing towards bacilliferous subtypes. Positive results in contacts represent healthy carriers and subclinical infection and these individuals can participate in transmission and spread of M. leprae in the community, even though they may not develop the disease. In endemic regions, contact monitoring is imperative in leprosy control for early case detection and chemoprophylaxis must be applied as prevention to disease development and disruption of transmission. / Dissertação (Mestrado)