The character of an urban void is defined by the built surrounding which determines the appearance and the function of the enclosed space. In modelling urban form, three major zones corresponding to this phenomenon may be distinguished: 1. Core 2. Transition Zone 3. Surrounding The transition zone contains the capacity to determine the prospective character of the framed void. It offers the possibility to intervene in the existing urban form, not by filling, but by emptying it. The void experiences a transformation from a neglected urban object to a clearly identified urban subject. This threshold towards the void serves as a mediating element between the two coexisting situations. It acts as a "coulisse" of an urban theater towards the void. / Master of Architecture

AIMS: To investigate the effects of Yoga on improving low back stability (threshold of stability, and mean total velocity of center of pressure), trunk strength (isometric strength in extension and flexion), and back endurance (isometric endurance in extension, flexion, and side laterals). METHODS: A pretest posttest control group experimental design was used. Sixteen participants, 10 females and 6 males, without a history of low back pain, and no prior experience of Yoga, were recruited. Yoga participants were recruited following registration in a yoga class; the control subjects were selected and recruited selectively in order to match the stature and body mass of the Yoga participant pool. Performance was measured prior to the beginning of Yoga exercises and 7 weeks later for both the groups. RESULTS: Contrary to the control group, the Yoga group significantly improved in terms of low back stability (decrease in threshold of stability by ~19%) and sway parameters (decrease in mean total velocity of COP by ~17%). CONCLUSIONS: The outcomes of this study illustrate the potential of Yoga as a low-impact exercise regime for improving low back stability via neuromuscular control and proprioception. There was no significant difference in trunk strength and endurance when comparing the two groups; therefore, the Yoga exercise was equally effective as the regular exercises. / Master of Science

Yes / In large industrial systems, alarm management is one of the most important issues to improve the safety and efficiency of systems in practice. Operators of such systems often have to deal with a numerous number of simultaneous alarms. Different kinds of thresholding or filtration are applied to decrease alarm nuisance and improve performance indices, such as Averaged Alarm Delay (ADD), Missed Alarm and False Alarm Rates (MAR and FAR). Among threshold-based approaches, variable thresholding methods are well-known for reducing the alarm nuisance and improving the performance of the alarm system. However, the literature suffers from the lack of an appropriate method to assess performance parameters of Variable Threshold Alarm Systems (VTASs). This study introduces two types of variable thresholding and proposes a novel approach for performance assessment of VTASs using Priority-AND gate and semi-Markov process. Application of semi-Markov process allows the proposed approach to consider industrial measurements with non-Gaussian distributions. In addition, the paper provides a genetic algorithm based optimized design process for optimal parameter setting to improve performance indices. The effectiveness of the proposed approach is illustrated via three numerical examples and through a comparison with previous studies. / Noavaran Electronic Adar Sameh company [Grant NO: IRAM17S1].

Les détecteurs à pixels Medipix ont été développés par la collaboration Medipix et permettent de faire de l'imagerie en temps réel. Leur surface active de près de $2\cm^2$ est divisée en 65536~pixels de $55\times 55\um^2$ chacun. Seize de ces détecteurs, les Medipix2, sont installés dans l'expérience ATLAS au CERN afin de mesurer en temps réel les champs de radiation produits par les collisions de hadrons au LHC. Ils seront prochainement remplacés par des Timepix, la plus récente version de ces détecteurs, qui permettent de mesurer directement l'énergie déposée dans chaque pixel en mode \textit{time-over-threshold} (TOT) lors du passage d'une particule dans le semi-conducteur. En vue d'améliorer l'analyse des données recueillies avec ces détecteurs Timepix dans ATLAS, un projet de simulation Geant4 a été amorcé par John Id\'rraga à l'Université de Montréal. Dans le cadre de l'expérience ATLAS, cette simulation pourra être utilisée conjointement avec Athena, le programme d'analyse d'ATLAS, et la simulation complète du détecteur ATLAS. Sous l'effet de leur propre répulsion, les porteurs de charge créés dans le semi-conducteur sont diffusés vers les pixels adjacents causant un dépôt d'énergie dans plusieurs pixels sous l'effet du partage de charges. Un modèle effectif de cette diffusion latérale a été développé pour reproduire ce phénomène sans résoudre d'équation différentielle de transport de charge. Ce modèle, ainsi que le mode TOT du Timepix, qui permet de mesurer l'énergie déposée dans le détecteur, ont été inclus dans la simulation afin de reproduire adéquatement les traces laissées par les particules dans le semi-conducteur. On a d'abord étalonné le détecteur pixel par pixel à l'aide d'une source de $\Am$ et de $\Ba$. Ensuite, on a validé la simulation à l'aide de mesures d'interactions de protons et de particules $\alpha$ produits au générateur Tandem van de Graaff du Laboratoire René-J.-A.-Lévesque de l'Université de Montréal. / The pixelated Medipix detectors have been developed by the Medipix Collaboration to perform real-time imaging. The semiconducting chip is divided into 65536 pixels of $55\times 55\um^2$ for a total active area of nearly $2\cm^2$. Because of their sensitivity to all kinds of particles, sixteen Medipix2 detectors (ATLAS-MPX) have been placed in the ATLAS detector and its cavern to measure for the radiation produced by the head-on proton collisions produced at the LHC. At the next ATLAS upgrade, the ATLAS-MPX network will be extended to include the Timepix detectors, the latest version that allows one to measure the total energy deposited in the semiconductor. To improve data analysis, a Geant4 simulation project of a Timepix detector was initiated by John Id\'arraga at the Université de Montréal. In the framework of the ATLAS experiment, this simulation could be used with Athena, the ATLAS analysis software, and the full ATLAS simulation. Due to their repulsivity, the charge carriers created by an incoming particle in the pixelated detector are spread over the surrounding pixels causing a charge sharing effect. An effective model has been developed to reproduce this effect without resolving the charge drift's differential equation. This model and the \textit{time-over-threshold} mode of the Timepix have been included in the simulation to reproduce the tracks left by the striking particles. First, one had to individually calibrate each pixel of the device with $\Am$ and $\Ba$ sources. The simulation's validation has been performed with low energy protons and $\alpha$ particles delivered by the van de Graaff Tandem at the Laboratoire René-J.-A.-Lévesque of the Université de Montréal.

Dans les sociétés industrialisées, les humains sont exposés à multiples sources de mouvements vibratoires. Jusqu'à présent, l’analyse de l'effet des stimuli vibratoire dans son ensemble a été bien développée, plus précisément en ce qui concerne le seuil de perception. Au cours des dernières années, diverses études ont analysé l'influence de certains facteurs.Cependant, l'effet d'une des composantes du stimulus sur la perception d'autres composants a été rarement rapporté. Dans ce cas, très peu d'information a été trouvée dans la littérature. Dans les deux études trouvées, le seuil absolu a été réévalué en considérant un second signal sinusoïdal. La valeur du seuil était plus élevée que ce qui a été estimé avec le stimulus simple. L'augmentation du seuil a été attribuée à l'effet de masquage. Basé sur ces observations, cette étude examine l'existence de l'effet de masquage dans les vibrations vertical du corps entière. Afin d'examiner l'effet de masquage, la différence entre le seuil absolu et le seuil masqué est nécessaire. Deux types de stimuli ont été utilisés : le stimulus masquage et le stimulus de test. Le masque est un signal de bruit à bande étroite entre 10 et 20 Hz, à trois niveaux d'amplitude différents. La sélection du stimulus de masque a été basée sur le modèle de masquage largement étudié dans certains domaines tels que l'acoustique, le domaine visuel et vibrotactile. Le stimulus de test est un signal sinusoïdale d'amplitude modulée à six fréquences différentes (30, 35, 40, 50, 60, 80 Hz. L'effet de la fréquence sur le seuil absolu estimé est similaire à ce qui a été indiqué par d'autres études. La détection du stimulus en présence du signal de masquage a été empêchée. Par conséquent, il est certainement clair que le phénomène de masquage a eu lieu. Les valeurs des seuils masqués étaient considérablement plus élevées que ceux correspondant aux seuils absolus. Le seuil décroît en fonction de la fréquence de test et l'effet de masque est plus important à haute qu’à faible niveau d'intensité du masque. Le démasquage est lié à l’écart entre les fréquences des signaux masquant et de test. Lorsque l’écart est faible, prévaut la reconnaissance de l’augmentation de l’intensité globale d'énergie. Si l’écart augmente, la discrimination des signaux prédomine. / In industrialized societies, humans are exposed to multiple sources of vibratory motions. To date, the analyses of the impact of vibratory stimuli as a whole have been well developed, more precisely with respect to perception threshold. Along recent years various studies have been analyzed the influence of some factors involved.However, the effect of one component of the stimulus in to perception of other components has been rarely reported. In this case, little information was found in the literature. In two studies found, the absolute threshold was revalued by integrating a second sinusoidal signal. The threshold value was higher that which has been estimated with the simple stimulus. The increase of threshold has been attributed to a masking effect. Based on these remarks, this study investigates the existence of masking effect for vertical whole body vibration, in particular to sitting position. To examine the masking effect, the difference between absolute and masked thresholds is required. Two types of stimuli have been used: the masking and the test stimulus. The masker is a narrow-band noise from 10 to 20 Hz at three different magnitude levels. The selection of mask stimulus was based on the masking model widely studied in acoustic, visual and vibrotactile areas. The test stimulus is a sinusoidal modulated amplitude signal at six different frequencies (30, 35, 40, 50, 60, 80 Hz). The frequency dependence of the absolute threshold estimated is similar to the results presented in other studies. The stimulus detection in the presence of the masking signal has been prevented. Therefore, it is certainly clear that the masking phenomenon occurred. The masked thresholds values were considerably higher than those absolute thresholds. The threshold decreases as a function of test frequency and the mask effect is more important at high than at low intensity masker levels. The unmasking is related to the difference between the mask and test signals frequencies. When the difference is small, the recognition of the increase in the overall energy intensity predominates. However, if the difference increases, then the discrimination of signals is dominant.

O propósito do presente estudo foi obter evidências de validade e reprodutibilidade dos limiares de variabilidade da frequência cardíaca (VFC) durante a corrida. Dezenove sujeitos homens, saudáveis e praticantes de corrida (30,4 ± 4,1 anos; 175,9 ± 6,4 cm; 74,3 ± 8,5 kg) foram submetidos a um teste progressivo máximo em esteira rolante com velocidade inicial 5 km.h-1 e incrementos de 1 km.h-1 a cada 3 minutos (1% de inclinação constante) até exaustão voluntária. Todos os indivíduos realizaram o reteste em um intervalo de tempo entre 48 horas e uma semana. Foram realizadas as medidas das trocas gasosas, do lactato sanguíneo e da VFC (plotagem de Poincaré). Os limiares aeróbio (LAe) e anaeróbio (LAn) foram determinados pelos limares de lactato, ventilatórios e da VFC. Para a comparação entre os métodos foi uitlizada ANOVA para medidas repetidas, acompanhada de teste de post hoc de Bonferroni. A reprodutibilidade das variáveis analisadas foram verificadas pela plotagem de Bland-Altman e pelo coeficiente de correlação intraclasse (CCI). Os resultados do presente estudo demonstraram que a velocidade correspondente ao segundo e terceiro modelos utilizados para se determinar o LA pela VFC não eram significativamente diferentes (p > 0,05) do primeiro limiar de lactato e ventilatório. Em relação ao LAn, não foram observadas diferenças significativas nas velocidades correspondentes ao LAn detectado pelos diferentes métodos (p > 0,05). Os valores do CCI estavam entre 0,69 a 0,80 (p < 0,001). Conclui-se que o LAe e o LAn podem ser identificados pela análise da VFC, desde que se utilize os procedimentos empregados na presente investigação / The aim of the present study was to obtain evidences of validity and reliability of the thresholds of heart rate variability (HRV). Nineteen male subjects, healthy and runners (30,4 ± 4,1 years; 175,9 ± 6,4 cm; 74,3 ± 8,5 kg) performed a progressive maximal test on a treadmill with initial velocity 5 km.h-1 e increases of 1 km.h-1 every 3 minutes (1% slope) until voluntary exhaustion. All subjects performed the retest at an interval of time between 48 hours and one week. It was measured gas exchange, blood lactate and heart rate variability (Poincaré plot). The aerobic threshold (AT) and anaerobic (AnT) were determined by lactate, ventilatory and heart rate variability. ANOVA for repeated measures and post-hoc test of Bonferroni was used to compare the methods. To analyze the reproducibility of the variables were used the Bland- Altman plots and intraclass correlation coefficient (ICC). The results of this study show that the velocity at the second and third models employed to determine the AT by HRV were not significantly different (p > 0.05) of the first lactate threshold and ventilatory. Similarly, there were no significant differences in the velocities corresponding to AnT detected by different methods (p> 0.05). The ICC values were between 0.69 to 0.80 (p < 0.001). We conclude that the AT and the AnT can be estimated by HRV analysis, since it utilizes the procedures employed in this study

Silicon nanowire based multiple gate metal oxide field effect transistors(MG-MOSFET) appear as replacements for conventional bulk transistors in post 45nm technology nodes. In such transistors the short channel effect(SCE) is controlled by the device geometry, and hence an undoped (or, lightly doped) ultra-thin body silicon nanowire is used to sustain the channel. The use of undoped body also solves several issues in bulk MOSFETs e.g., random dopant fluctuations, mobility degradation and compatibility with midgap metal gates. The electrostatic integrity of such devices increases with the scaling down of the body thickness. Since the quantization of electron energy cannot be ignored in such ultra-thin body devices, it is extremely important to consider quantum effects in their threshold voltage models. Most of the models reported so far are valid for long channel double gate devices. Only Munteanu et al. [Journal of non-crystalline solids vol 351 pp 1911-1918 2005] have reported threshold voltage model for short channel symmetric double gate MOSFET, however it involves unphysical fitting parameters. Only Munteanu et al.[Molecular simulation vol 31 pp 839-845 2005] reported threshold voltage model for quad gate transistor which is implicit in nature. On the other hand no modeling work has been reported for other types of MG-MOSFETs (e.g., tri gate, cylindrical body)apart from numerical simulation results. In this work we report physically based closed form quantum threshold voltage models for short channel symmetric double gate, quad gate and cylindrical body gate-all-around MOSFETs. In these devices quantum effects aries mainly due to the structural confinement of electron energy. Proposed models are based on the analytical solution of two or three-dimensional Poisson equation and one or two-dimensional Schrodinger equation depending on the device geometries. Judicial approximations have been taken to simplify the models in order to make them closed form and efficient for large scale circuit simulation. Effort has also been put to model the quantum threshold voltage of tri gate MOSFET. However it is found that the energy quantization in tri gate devices are mainly due to electronic confinement and hence it is very difficult to develop closed form analytical equations for the threshold voltage. Thus in this work the modeling of tri gate devices have been limited to long channel cases. All the models are validated against the professional numerical simulator.

The ability to tune the properties over a wide range of values by changing the additives, composition, etc., has made chalcogenide glassy semiconductors, most interesting from both fundamental physics as well as technology point of view. In particular, the occurrence of the two network topological thresholds namely the Rigidity Percolation Threshold (RPT) and the Chemical Threshold (CT) and their influence on various properties of chalcogenide glasses have been of immense interest during the last three decades. The Rigidity Percolation Threshold (also known as the Stiffness Threshold or Mechanical Threshold) corresponds to the composition at which the material transforms from a floppy polymeric glass to a rigid amorphous solid, whereas at Chemical Threshold the sample tends towards an ordered state. Though the rigidity percolation has been considered for long to occur at a critical threshold defined by the constraint’s theory, the recent theoretical and experimental investigations have found the RPT to occur over a range of compositions. In systems exhibiting an extended rigidity percolation, two distinct transitions namely from a floppy to an isostatically rigid phase and from an isostatically rigid to a stressed rigid phase are seen. In the category of chalcogenide glasses, tellurides have been found to exhibit interesting properties including the phenomenon of electrical switching which finds applications in Phase Change Memories (PCM). Studies on various thermal, electrical and photoelectrical properties of glassy tellurides help us in identifying suitable materials for different technological applications. This thesis deals with Differential Scanning Calorimetric (DSC) & Temperature Modulated Alternating Differential Scanning Calorimetric (ADSC) studies, electrical switching investigations, photoconductivity & photothermal measurements on certain metal doped telluride glasses. The composition dependence of properties such as glass transition & crystallization temperatures, switching voltage, thermal diffusivity, photosensitivity, etc., have been analyzed to obtain information about topological thresholds, thermally reversing window, etc. The first chapter of thesis provides an overview of properties of amorphous semiconductors, in particular chalcogenide glasses. The local & defect structure, the electronic band structure & electrical properties, electrical switching behavior, etc., are discussed in detail. The theoretical aspects related to the experiments undertaken in this thesis work have also been described. The instrumentation used for various experiments conducted to measure thermal, electrical, photoelectrical and photothermal properties have been discussed in chapter two. The chapter three deals with the photocurrent measurements on As40Te60-xInx (7.5 ≤ x ≤ 16.5) glasses. In these samples, it has been found that the photocurrent increases with illumination, which is understood on the basis of the large dielectric constant and also due to the presence of a large number of positively charged defect states. Further, the composition dependence of the conductivity activation energy and the photosensitivity exhibit a maximum at x = 12.5 (<r> = 2.65) and a minimum at x = 15.0 (<r> = 2.70) which has been identified to be the Rigidity Percolation Threshold (RPT) and the Chemical Threshold (CT) respectively. The results of electrical switching, DSC and Photothermal Deflection (PTD) studies on As20Te80-xGax (7.5 ≤ x ≤ 18.5) glasses, undertaken to elucidate the network topological thresholds, are described in chapter four. It has been found that all the As20Te80-xGax glasses studied exhibit memory type electrical switching. The switching voltage (VT) of these glasses increases monotonically with x, in the composition range 7.5 ≤ x ≤ 15.0. The increase in VT with gallium addition leads to a local maximum at x = 15.0 and VT decreases with x thereafter, reaching a distinct minimum at x = 17.5. Based on the variation with composition of the electrical switching voltages, the composition x = 15.0 and x = 17.5 have been identified to be the rigidity percolation and chemical thresholds of the As20Te80-xGax glassy system respectively. Further, the DSC studies indicate that As20Te80-xGax glasses exhibit a single glass transition (Tg) and two crystallization reactions (Tc1 & Tc2) upon heating. There is no appreciable change in Tg of As20Te80-xGax glasses with the addition of upto about10 atom% of Ga, whereas a continuous increase is seen in the crystallization temperature (Tc1). It is interesting to note that both Tg and Tc1 exhibit a maximum at x = 15.0 and a minimum at x = 17.5, the compositions identified to be the RPT and CT respectively by the switching experiments. The composition dependence of thermal diffusivity estimated from the PTD signal, indicate the occurrence of an extended stiffness transition in As20Te80-xGax glasses, with the compositions x = 9.0 and x = 15.0 being the onset and the completion of an extended rigidity percolation. A maximum and a minimum are seen in the thermal diffusivity respectively at these compositions. Further, a second maximum is seen in the thermal diffusivity of As20Te80-xGax glasses, the Chemical Threshold (CT) of the glassy system. The fifth chapter of the thesis describes the ADSC, electrical switching and photocurrent measurements on Ge15Te85-xInx (1 ≤ x ≤ 11) glasses. It is found there is not much change in the Tg of Ge15Te85-xInx glasses in the composition range 1 ≤ x ≤ 3. An increase is seen in Tg beyond x = 3, which continues until x = 11. Further, the composition dependence of non-reversing enthalpy shows the presence of a thermally reversing window in the compositions range x = 3 and x = 7. Electrical switching studies indicate that Ge15Te85-xInx glasses exhibit threshold type of switching at input currents below 2 mA. It is observed that switching voltages decrease initially with indium addition, exhibiting a minimum at x = 3, the onset of the extended rigidity percolation as revealed by ADSC. An increase is seen in VT above x = 3, which proceeds till x = 8, with a change in slope (lower to higher) seen around 7 atom% of indium which corresponds to the completion of the stiffness transition. The reversal in trend exhibited in the variation of VT at x = 8, leads to a well defined minimum around x = 9, the chemical threshold of the Ge15Te85-xInx glassy system. Photocurrent measurements indicate that there is no photodegradation in Ge15Te85-xInx glasses with x < 3, whereas samples with x ≥ 3 show photodegradation behavior. The composition dependent variation in the glass transition temperature has been attributed for this behavior. Further, the composition dependence of photo sensitivity has been found to show the signatures of the extended rigidity percolation and the chemical threshold in Ge15Te85-xInx glasses. The last chapter of thesis (chapter six) summarizes the results obtained and also the scope of future work to be undertaken.

Les détecteurs à pixels Medipix ont été développés par la collaboration Medipix et permettent de faire de l'imagerie en temps réel. Leur surface active de près de $2\cm^2$ est divisée en 65536~pixels de $55\times 55\um^2$ chacun. Seize de ces détecteurs, les Medipix2, sont installés dans l'expérience ATLAS au CERN afin de mesurer en temps réel les champs de radiation produits par les collisions de hadrons au LHC. Ils seront prochainement remplacés par des Timepix, la plus récente version de ces détecteurs, qui permettent de mesurer directement l'énergie déposée dans chaque pixel en mode \textit{time-over-threshold} (TOT) lors du passage d'une particule dans le semi-conducteur. En vue d'améliorer l'analyse des données recueillies avec ces détecteurs Timepix dans ATLAS, un projet de simulation Geant4 a été amorcé par John Id\'rraga à l'Université de Montréal. Dans le cadre de l'expérience ATLAS, cette simulation pourra être utilisée conjointement avec Athena, le programme d'analyse d'ATLAS, et la simulation complète du détecteur ATLAS. Sous l'effet de leur propre répulsion, les porteurs de charge créés dans le semi-conducteur sont diffusés vers les pixels adjacents causant un dépôt d'énergie dans plusieurs pixels sous l'effet du partage de charges. Un modèle effectif de cette diffusion latérale a été développé pour reproduire ce phénomène sans résoudre d'équation différentielle de transport de charge. Ce modèle, ainsi que le mode TOT du Timepix, qui permet de mesurer l'énergie déposée dans le détecteur, ont été inclus dans la simulation afin de reproduire adéquatement les traces laissées par les particules dans le semi-conducteur. On a d'abord étalonné le détecteur pixel par pixel à l'aide d'une source de $\Am$ et de $\Ba$. Ensuite, on a validé la simulation à l'aide de mesures d'interactions de protons et de particules $\alpha$ produits au générateur Tandem van de Graaff du Laboratoire René-J.-A.-Lévesque de l'Université de Montréal. / The pixelated Medipix detectors have been developed by the Medipix Collaboration to perform real-time imaging. The semiconducting chip is divided into 65536 pixels of $55\times 55\um^2$ for a total active area of nearly $2\cm^2$. Because of their sensitivity to all kinds of particles, sixteen Medipix2 detectors (ATLAS-MPX) have been placed in the ATLAS detector and its cavern to measure for the radiation produced by the head-on proton collisions produced at the LHC. At the next ATLAS upgrade, the ATLAS-MPX network will be extended to include the Timepix detectors, the latest version that allows one to measure the total energy deposited in the semiconductor. To improve data analysis, a Geant4 simulation project of a Timepix detector was initiated by John Id\'arraga at the Université de Montréal. In the framework of the ATLAS experiment, this simulation could be used with Athena, the ATLAS analysis software, and the full ATLAS simulation. Due to their repulsivity, the charge carriers created by an incoming particle in the pixelated detector are spread over the surrounding pixels causing a charge sharing effect. An effective model has been developed to reproduce this effect without resolving the charge drift's differential equation. This model and the \textit{time-over-threshold} mode of the Timepix have been included in the simulation to reproduce the tracks left by the striking particles. First, one had to individually calibrate each pixel of the device with $\Am$ and $\Ba$ sources. The simulation's validation has been performed with low energy protons and $\alpha$ particles delivered by the van de Graaff Tandem at the Laboratoire René-J.-A.-Lévesque of the Université de Montréal.

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-04-13T13:50:42Z No. of bitstreams: 1 arquivo total.pdf: 2010347 bytes, checksum: 3a95a7a08d68f7438a013ab7bc0d2bc3 (MD5) / Made available in DSpace on 2016-04-13T13:50:42Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 2010347 bytes, checksum: 3a95a7a08d68f7438a013ab7bc0d2bc3 (MD5) Previous issue date: 2015-12-04 / The thesis studies, in three chapters, on the provision of public goods in municipalities. The first chapter puts in competition two alternative specifications, one on the demand side and another on the supply side, to a set of 5285 municipalities data for 2010 in order to test the hypothesis that the relevance of the models that explain the behavior local government spending can depend on the size of the population of the jurisdictions. The econometric methodology uses a combination of Test J proposed by Davidson and MacKinnon (1981), with the threshold suggested by Hansen (2000), as a data screening method to test whether the response of local governments to their constituents is stable between small and large municipalities. Results show that the median voter model applies to smaller cities, with great population size ranging between 13604 and 13661 inhabitants, depending on the congestion function used. Nevertheless, it rejected in 2293 municipalities, for which the model-oriented supply fits better. In the second chapter, these alternative models of determination of public provision in order to measure the impact of the size of cities on the quality of public services applies - via analysis of advertising and rivalry of goods - in 5268 Brazilian municipalities based on the Theory of Clubs. For both models, the results point to the existence of spatial correlation between municipalities, suggesting that spending patterns in a given locality influence on the fiscal decisions of neighbors. Proves the hypothesis that the size of the clubs, and the cost of utilities differentiate the results of the provision of action, supporting the literature on the subject which argues that in smaller jurisdictions proximity of voters with its public officials exerts more pressure and control over their political acts, and that aggregate individual preferences have less heterogeneity and can represent the community as a whole. This result yields a larger congestion effect to the larger cities, which goes against the international literature. Finally, using a set of data that make up Brazilian localities Public Consortia Inter-municipal public services, the third chapter aims to establish empirical evidence for a phenomenon called by Oates (1988) as "zoo-effect." According to this effect, the lowest level of expenditure in smaller towns should not be explained by the smaller clusters, but simply by the fact that certain categories of spending - like a zoo - they need a minimum population size to be provided. Thus, the positive relationship between population size and local spending on public services does not take into account the fact that in the most populous cities, the basket of services offered is broader and more diverse, and for this reason, estimates of existing congestion tend to be overestimated. By spatial statistics confirmed the hypothesis of the zoo effect on municipalities, and that the more diversified the range of services expands the range of services in neighboring areas, which explains the interaction between the municipalities as a way to get better and higher level of public services to its citizens. Evidence shows that the intensity of the effect depends on the urban-rural gradient, with the biggest phenomenon in urban areas due to more substantial economies of scale in these locations. / A tese versa, em três capítulos, sobre a provisão de bens públicos nos municípios brasileiros. O primeiro capítulo coloca em competição duas especificações alternativas, uma do lado da demanda e outra do lado da oferta, para um conjunto de dados de 5285 municípios brasileiros para 2010, a fim de testar a hipótese de que a relevância dos modelos que explicam o comportamento das despesas públicas locais pode depender do tamanho da população das jurisdições. A metodologia econométrica usa a combinação do Teste J, proposto por Davidson e MacKinnon (1981), com o Threshold, sugerido por Hansen (2000), como um método de triagem de dados capaz de testar se a resposta dos governos locais aos seus eleitores é estável entre os municípios de pequeno e de grande porte. Os resultados permitem inferir que o modelo do eleitor mediano aplica-se às cidades menores, com tamanho ótimo populacional variando entre 13604 e 13661 habitantes, dependendo da função de congestionamento utilizada. Não obstante, é rejeitado em 2293 municípios, para os quais o modelo orientado para a oferta apresenta melhor ajuste. No segundo capítulo, aplica-se os referidos modelos alternativos de determinação da provisão pública a fim de mensurar o impacto do tamanho das cidades sobre a qualidade dos serviços públicos - via análise da publicidade e da rivalidade dos bens – em 5268 municípios brasileiros baseado na Teoria dos Clubes. Para os dois modelos, os resultados apontam a existência da correlação espacial entre os municípios, sugerindo que os padrões de gastos em determinada localidade influencia nas decisões fiscais de vizinhos. Comprova-se a hipótese de que o tamanho dos clubes e o custo dos serviços públicos diferenciam os resultados da ação de provisão, corroborando com a literatura sobre o tema a qual defende que em jurisdições menores a proximidade dos eleitores com seus agentes públicos exerce maior pressão e controle sobre seus atos políticos, e que preferências individuais agregadas apresentam menor heterogeneidade e podem representar a comunidade como um todo. Este resultado gera um efeito congestionamento maior para as maiores cidades, o que vai de encontro à literatura internacional. Por fim, usando um conjunto de dados de localidades brasileiras que formam Consórcios Públicos Intermunicipais de serviços públicos, o terceiro capítulo visa estabelecer evidências empíricas para um fenômeno denominado por Oates (1988) como “efeito-zoo”. De acordo com esse efeito, o nível mais baixo de despesas em cidades menores não deve ser explicado pela menor aglomeração, mas simplesmente pelo fato de que certas categorias de gastos - como um zoológico - precisam de um tamanho mínimo populacional para serem fornecidos. Destarte, a relação positiva entre o tamanho da população e o gasto local em serviços públicos não leva em conta o fato de que nos municípios mais populosos, a cesta de serviços ofertados é mais ampla e mais diversificada, e por essa razão as estimativas de congestionamento existentes tendem a ser superestimadas. Através da estatística espacial confirmou-se a hipótese do efeito zoo nos municípios brasileiros, e que a maior diversificação na gama de serviços expande a oferta de serviços em áreas vizinhas, justificando a interação entre os municípios como forma de se obter melhor e maior nível de serviços públicos para seus cidadãos. As evidências apontam que a intensidade do efeito depende do gradiente urbano-rural, sendo o fenômeno maior em áreas urbanizadas, devido às economias de escala mais substanciais nessas localidades.