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Contrairement aux mammifères, le poisson zèbre a la capacité de régénérer son coeur après une blessure importante. Une meilleure compréhension de ce phénomène pourrait contribuer à la conception de thérapies cliniques pour améliorer la régénération cardiaque des mammifères. Dans cette étude, nous avons identifié des voies de signalisation de la régénération cardiaque du poisson zèbre utilisant un criblage génétique chimique. De plus, nous avons identifier la présence d'un facteur de transcription bHLH, TAL1 et nous avons montrer son importance au cours de la régénération cardiaque du poisson zèbre. Enfin, nous avons examiner le rôle du système immunitaire lors de la régénération cardiaque du poisson zèbre et nous avons montrer que la sécrétion des metalloprotéinases (MMP14) par les macrophages permettait la dissolution du caillot sanguin, processus nécessaire pour la réussite de la régénération cardiaque. / Unlike mammals, zebrafish have the ability to regenerate their heart after substantial injury. A deeper understanding of this phenomenon could aid in the design of clinical therapies to enhance mammalian cardiac regeneration. In this study, we have identified signaling pathways in zebrafish heart regeneration using a chemical genetic screen. Furthermore, we identify the presence of a bHLH transcription factor, Tal1 and show its requirement during zebrafish cardiac regeneration. Finally, we examine the role of the immune system during zebrafish heart regeneration and demonstrate a model of scar removal by MMP14 positive macrophages and show that this process is required for successful heart regeneration to occur.

The statistical inferences about the parameters of Binomial-Poisson hierarchy model are discussed. Based on the estimators of paired observations we consider the other two cases with extra observations on both the first and second layer of the model. The MLEs of lambda and p are derived and it is also proved the MLE lambda is also the UMVUE of lambda. By using multivariate central limit theory and large sample theory, both the estimators based on extra observations on the first and second layer are obtained respectively. The performances of the estimators are compared numerically based on extensive Monte Carlo simulation. Simulation studies indicate that the performance of the estimators is more efficient than those only based on paired observations. Inference about the confidence interval for p is presented for both cases. The efficiency of the estimators is compared with condition given that same number of extra observations is provided.

Orientador : Mauro S. de F. Marques / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Ciencia da Computação / Made available in DSpace on 2018-07-18T15:29:36Z (GMT). No. of bitstreams: 1 OlivaresAguilera_BenitoOrlando_M.pdf: 2602283 bytes, checksum: 0360facee12008390206aafe0b971c67 (MD5) Previous issue date: 1993 / Resumo: Não informado / Abstract: Not informed / Mestrado / Mestre em Estatística

Neste trabalho apresentamos simulações em dinâmica molecular de uma “brush” de polieletrólitos esférica, cercada de contraíons, em um meio livre de sais, onde a heterogeneidade dielétrica entre os materiais é levada em consideração. Estes conjuntos de polieletrólitos tem sido estudados experimentalmente de maneira ampla, tendo mostrado uma gama de diferentes aplicações como o uso para biosseparação e como portadores de drogas/genes para transporte controlado. Entretanto, teorias e simulações formais que expliquem o seu comportamento não são tão numerosas. A teoria e o trabalho presentes são detalhados nesta dissertação na forma de múltiplas seções, mas os resultados permanecem contidos ao artigo anexado1 publicado em 2017. Começamos com uma breve introdução do trabalho e então apresentamos o artigo, posteriormente a teoria é melhor explorada no apêndice da metodologia, finalmente, terminamos com as considerações finais para com os resultados do trabalho e as conclusões do projeto. O projeto consiste das simulações anteriormente mencionadas, as quais tinham o propósito principal de investigar os efeitos da descontinuidade dielétrica, entre o núcleo da “brush” e o meio em que está envolta, sobre a dinâmica do sistema. Isso é investigado através do uso do método de cargas imagem. As propriedades da “brush” de polieletrólitos também são obtidas para diferentes parâmetros, dentre os quais, a valência dos contra íons, o raio da nanopartícula central e a carga total da “brush”. Uma teoria de campo médio é apresentada para comparação com os perfis de densidade obtidos para os contra íons monovalentes, e nós terminamos o artigo apresentando as propriedades osmóticas do sistema. / In this work we present a molecular dynamics simulation of a polyelectrolyte spherical brush and counterions in a salt-free medium, in which the dielectric inhomogeneity between materials is taken in consideration. Polyelectrolyte brushes have been studied experimentally broadly, having shown a range of different applications such as for bioseparation and targeted drug/gene delivery. In spite of that, formal simulations and theories explaining its behavior are not as numerous. The theory and the work we present are unfold into more details throughout the thesis in the form of multiple sections, but the results remain contained to the paper annexed1, published in 2017. We start with a brief introduction of the work and then present the paper, later on, the theory is further explored in the methodology appendix, and we finish with the final considerations for the work results and the project conclusion. The project consists of the aforementioned simulations with the main purpose of investigating the effect of the dielectric discontinuity, between the brush core and its surrounding medium, over the dynamics of the system. This is investigated through the use of the method of image charges. Properties of the polyelectrolyte brush are obtained for different parameters, including valence of the counterions, radius of the nanoparticle and the brush total charge. A mean-field theory is presented for the comparison with density profiles obtained for monovalent counterions, and we finish the paper by presenting the osmotic properties of the system.

Les résultats présentés dans cette thèse portent sur la construction et la simulation numérique de modèles théoriques de plasmas en présence d'une paroi absorbante. Ces modèles se basent sur des systèmes de Vlasov-Poisson ou Vlasov-Ampère à deux espèces en présence de conditions limites. Les solutions stationnaires recherchées vérifient l'équilibre des flux de charges dans la direction perpendiculaire à la paroi. Cette propriété s'appelle l'ambipolarité. A travers l'étude d'une équation de Poisson non linéaire, on montre le caractère bien posé d'un système de Vlasov-Poisson stationnaire 1d-1v pour lequel on détermine des distributions de particules entrantes et un potential au mur qui induisent l'ambipolarité et une densité de charge positive. On donne également une estimation de la taille de la couche limite au mur. Ces résultats sont illustrés numériquement. On prouve ensuite la stabilité linéaire des solutions stationnaires électroniques pour un modèle de Vlasov-Ampère instationnaire. Enfin, on étudie un modèle de Vlasov-Poisson stationnaire 1d-3v en présence d'un champ magnétique constant et parallèle à la paroi. On détermine les distributions de particules entrantes et un potentiel au mur qui induisent l'ambipolarité. On étudie une équation de Poisson non linéaire associée au modèle à l'aide d'une fonctionnelle non linéaire d'énergie qui admet des minimiseurs. On établit des bornes de paramètres à l'intérieur desquelles notre modèle s'applique et on propose une interprétation des résultats. / This thesis focuses on the construction and the numerical simulation theoretical models of plasmas in interaction with an absorbing wall. These models are based on two species Vlasov-Poisson or Vlasov-Ampère systems in the presence of boundary conditions. The expected stationary solutions must verify the balance of the flux of charges in the orthogonal direction to the wall. This feature is called the ambipolarity.Through the study of a non linear Poisson equation, we prove the well-posedness of 1d-1v stationary Vlasov-Poisson system, for which we determine incoming particles distributions and a wall potential that induces the ambipolarity as well as a non negative charge density hold. We also give a quantitative estimates of the thickness of the boundary layer that develops at the wall. These results are illustrated numerically. We prove the linear stability of the electronic stationary solution for a non-stationary Vlasov-Ampère system. Finally, we study a 1d-3v stationary Vlasov-Poisson system in the presence of a constant and parallel to the wall magnetic field . We determine incoming particles distributions and a wall potential so that the ambipolarity holds. We study a non linear Poisson equation through a non linear functional energy that admits minimizers. We established some bounds on the numerical parameters inside which, our model is relevant and we propose an interpretation of the results.

Consider n players whose "scores" are independent and identically distributed values {Xi}i=1n from some discrete distribution F. We pay special attention to the cases where (i) F is geometric with parameter p{combining right arrow above}0 and (ii) F is uniform on {1,2,. . . ,N}; the latter case clearly corresponds to the classical occupancy problem. The quantities of interest to us are, first, the U-statistic W which counts the number of "ties" between pairs i, j; second, the univariate statistic Yr, which counts the number of strict r-way ties between contestants, i.e., episodes of the form Xi1=Xi2=. . .=Xir; Xj≠Xi1;j≠i1,i2,. . . ,ir; and, last but not least, the multivariate vector ZAB=(YA, YA+1,. . . ,YB). We provide Poisson approximations for the distributions of W, Yr and ZAB under some general conditions. New results on the joint distribution of cell counts in the occupancy problem are derived as a corollary.

The univariate and bivariate central chi-square- and F distributions have received a decent amount of attention in the literature during the past few decades; the noncentral counterparts of these distributions have been much less present. This study enriches the existing literature by proposing bivariate noncentral chi-square and F distributions via the employment of the compounding method with Poisson probabilities. This method has been used to a limited extent in the field of distribution theory to obtain univariate noncentral distributions; this study extends some results in literature to the corresponding bivariate setting. The process which is followed to obtain such bivariate noncentral distributions is systematically described and motivated. Some distributions of composites (univariate functions of the dependent components of the bivariate distributions) are derived and studied, in particular the product, ratio, and proportion. The benefit of introducing these bivariate noncentral distributions and their respective composites is demonstrated by graphical representations of their probability density functions. Furthermore, an example of possible application is given and discussed to illustrate the versatility of the proposed models. / Dissertation (MSc)--University of Pretoria, 2014. / Statistics / MSc / Unrestricted

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The red imported fire ant (Solenopsis invicta)(RIFA) is a major pest in the United States, causing serious economic and human costs. This study explored the feasibility of using digital aerial remote sensing in multispectral/multitemporal detection and mapping of RIFA mounds. Comparison of photointerpretive mound counts versus ground control counts was performed within two grass types, common Bermuda and tall fescue. Flights collecting digital image data occurred at three intervals in 2009, with ground truth data collected collaterally. Poisson regression count modeling was first utilized for analysis of both datasets. Moran's Index geospatial analysis was applied following the Poisson model. Outcomes in this study from these models demonstrate their ability to robustly support studies for tracking and control of RIFA or other pest populations. Additionally, in one location, type of grass cover appeared to affect detectability of mounds between the two methods.