A Generalization of a Theorem of Boyd and Lawton

Ce mémoire s’applique à étudier d’abord, dans la première partie, la mesure de Mahler des polynômes à une seule variable. Il commence en donnant des définitions et quelques résultats pertinents pour le calcul de telle hauteur. Il aborde aussi le sujet de la question de Lehmer, la conjecture la plus célèbre dans le domaine, donne quelques exemples et résultats ayant pour but de résoudre la question. Ensuite, il y a l’extension de la mesure de Mahler sur les polynômes à plusieurs variables, une démarche semblable au premier cas de la mesure de Mahler, et le sujet des points limites avec quelques exemples. Dans la seconde partie, on commence par donner des définitions concernant un ordre supérieur de la mesure de Mahler, et des généralisations en passant des polynômes simples aux polynômes à plusieurs variables. La question de Lehmer existe aussi dans le domaine de la mesure de Mahler supérieure, mais avec des réponses totalement différentes. À la fin, on arrive à notre objectif, qui sera la démonstration de la généralisation d’un théorème de Boyd-Lawton, ce dernier met en évidence une relation entre la mesure de Mahler des polynômes à plusieurs variables avec la limite de la mesure de Mahler des polynômes à une seule variable. Ce résultat a des conséquences en termes de la conjecture de Lehmer et sert à clarifier la relation entre les valeurs de la mesure de Mahler des polynômes à une variable et celles des polynômes à plusieurs variables, qui, en effet, sont très différentes en nature.

A study of sexuality following traumatic brain injury : moving towards the validation of a biopsychosocial model

L’étude de la sexualité dans le contexte des maladies neurologiques est un domaine émergent qui nous permet de mieux comprendre les corrélats cérébraux et neurocomportementaux de divers aspects de la sexualité. Les changements au sujet de la sexualité sont fréquents à la suite de troubles neurologiques tels que les blessures de la moelle épinière, la sclérose en plaques, l’accident vasculaire cérébral, l'épilepsie et les traumatismes craniocérébraux (TCC). Compte tenu de la complexité de la sexualité après un TCC, celle-ci doit être analysée à partir d'une perspective biopsychosociale qui comprend trois facteurs interdépendants : a) les facteurs neuropsychologiques et psychologiques, b) les variables médicales et physiques, et c) les facteurs relationnels. L’objectif de cette thèse était d’étudier certains éléments de la sexualité auprès de personnes ayant subi un TCC afin de fournir des preuves empiriques pour contribuer à la validation d’une perspective biopsychosociale de la sexualité après un TCC. Trois études quantitatives originales ont été effectuées auprès de personnes ayant subi un TCC léger, modéré ou grave et ayant reçu des services de réadaptation post-TCC, et d’un groupe de témoins en bonne santé, tous vivant dans la communauté. Les groupes étaient comparables en ce qui concerne l’âge, le sexe, le nombre d’années de scolarité, le statut d’emploi et relationnel, et le revenu annuel. Les variables ciblant la sexualité, incluses dans cette thèse, étaient la qualité de vie sexuelle, le comportement sexuel à risque, et la sociosexualité (p. ex., les différences individuelles en ce qui concerne la volonté d’une personne à avoir des relations sexuelles sans engagement). Les variables neuropsychologiques et psychologiques incluaient les fonctions exécutives, la dépression et l’anxiété. Les aspects médicaux et physiques englobaient les symptômes postcommotionnels. Les facteurs relationnels comprenaient les attitudes envers l'infidélité. Les résultats démontrent que par rapport aux témoins en santé, les individus avec un TCC ont montré une diminution de la qualité de vie sexuelle, alors que les groupes étaient comparables sur le plan du comportement sexuel à risque, de la sociosexualité et des attitudes envers l'infidélité. Par ailleurs, les résultats ont montré une différence entre les hommes et les femmes sur le plan de la sociosexualité (p. ex., plus restrictive chez la femme). Chez les personnes ayant subi un TCC, une faible qualité de vie sexuelle était significativement associée à un nombre élevé de symptômes postcommotionnels, un comportement sexuel plus à risque corrélait avec une plus grande fréquence de symptômes dysexécutifs, et une plus faible acceptation de l'infidélité était liée à une sociosexualité moins restrictive. Les résultats de ces trois études soutiennent une perspective biopsychosociale de la sexualité après le TCC. Elles apportent des connaissances nouvelles en ce qui a trait aux domaines de la sexualité qui peuvent être touchés après un TCC, ainsi qu’à certaines variables neuropsychologiques et psychologiques, médicales et physiques, et relationnelles qui sont associées à ces changements. Les implications théoriques, ainsi que pour la pratique clinique et la réadaptation sont discutées. Les limitations des études sont présentées et des recommandations pour la recherche sont proposées. Le modèle biopsychosocial peut être utilisé comme une référence pour guider la recherche future dans ce domaine. D’autres études sur la sexualité et le développement d'interventions multidisciplinaires dans ce domaine pour les personnes TCC sont nécessaires.

Performance of District Industries Centers in Kerala : An Application of augmented solow Model

This thesis "Entitled performance of district industries centres in kerala :An application of augmented solow model.The first chapter deals with evolution of approaches for promoting small scale production and the growth of small scale industries in india.the developing countries face the problems like sluggish growth capital shortages high levels of unemployment,enoromous rural-urban economic disparities regional inequalities increasing concentration of capital and chronic difficulities in the export sector.Review of literature and methodology of the study are presented in the second chapter. In the third chapter an attempt has been made to make an in-depth study of the emergence and growth of district of district industries centres.In the chapter four an attempt was made to study the organisational structure of DICs functions and responsibilities assigned to the functional managers and performance of the functionaries.

Investigations On The Development Of An Ann Model & Visual Manipulation Approach For 2-D Dft Computation In Image Processing

This thesis is an outcome of the investigations carried out on the development of an Artificial Neural Network (ANN) model to implement 2-D DFT at high speed. A new definition of 2-D DFT relation is presented. This new definition enables DFT computation organized in stages involving only real addition except at the final stage of computation. The number of stages is always fixed at 4. Two different strategies are proposed. 1) A visual representation of 2-D DFT coefficients. 2) A neural network approach. The visual representation scheme can be used to compute, analyze and manipulate 2D signals such as images in the frequency domain in terms of symbols derived from 2x2 DFT. This, in turn, can be represented in terms of real data. This approach can help analyze signals in the frequency domain even without computing the DFT coefficients. A hierarchical neural network model is developed to implement 2-D DFT. Presently, this model is capable of implementing 2-D DFT for a particular order N such that ((N))4 = 2. The model can be developed into one that can implement the 2-D DFT for any order N upto a set maximum limited by the hardware constraints. The reported method shows a potential in implementing the 2-D DF T in hardware as a VLSI / ASIC

Foster carer experience in Spain : Analysis of the vulnerabilities of a permanent model

Resumen tomado de la publicaci??n

Nuclear magnetic resonance chemical shifts with the statistical average of orbital-dependent model potentials in Kohn-Sham density functional theory

The performance of the SAOP potential for the calculation of NMR chemical shifts was evaluated. SAOP results show considerable improvement with respect to previous potentials, like VWN or BP86, at least for the carbon, nitrogen, oxygen, and fluorine chemical shifts. Furthermore, a few NMR calculations carried out on third period atoms (S, P, and Cl) improved when using the SAOP potential

Wavelets and the generalization of the variogram

The experimental variogram computed in the usual way by the method of moments and the Haar wavelet transform are similar in that they filter data and yield informative summaries that may be interpreted. The variogram filters out constant values; wavelets can filter variation at several spatial scales and thereby provide a richer repertoire for analysis and demand no assumptions other than that of finite variance. This paper compares the two functions, identifying that part of the Haar wavelet transform that gives it its advantages. It goes on to show that the generalized variogram of order k=1, 2, and 3 filters linear, quadratic, and cubic polynomials from the data, respectively, which correspond with more complex wavelets in Daubechies's family. The additional filter coefficients of the latter can reveal features of the data that are not evident in its usual form. Three examples in which data recorded at regular intervals on transects are analyzed illustrate the extended form of the variogram. The apparent periodicity of gilgais in Australia seems to be accentuated as filter coefficients are added, but otherwise the analysis provides no new insight. Analysis of hyerpsectral data with a strong linear trend showed that the wavelet-based variograms filtered it out. Adding filter coefficients in the analysis of the topsoil across the Jurassic scarplands of England changed the upper bound of the variogram; it then resembled the within-class variogram computed by the method of moments. To elucidate these results, we simulated several series of data to represent a random process with values fluctuating about a mean, data with long-range linear trend, data with local trend, and data with stepped transitions. The results suggest that the wavelet variogram can filter out the effects of long-range trend, but not local trend, and of transitions from one class to another, as across boundaries.

Use of a crop model ensemble to quantify CO2 stimulation of water-stressed and well-watered crops

Increased atmospheric concentrations of carbon dioxide (CO2) will benefit the yield of most crops. Two free air CO2 enrichment (FACE) meta-analyses have shown increases in yield of between 0 and 73% for C3 crops. Despite this large range, few crop modelling studies quantify the uncertainty inherent in the parameterisation of crop growth and development. We present a novel perturbed-parameter method of crop model simulation, which uses some constraints from observations, that does this. The model used is the groundnut (i.e. peanut; Arachis hypogaea L.) version of the general large-area model for annual crops (GLAM). The conclusions are of relevance to C3 crops in general. The increases in yield simulated by GLAM for doubled CO2 were between 16 and 62%. The difference in mean percentage increase between well-watered and water-stressed simulations was 6.8. These results were compared to FACE and controlled environment studies, and to sensitivity tests on two other crop models of differing levels of complexity: CROPGRO, and the groundnut model of Hammer et al. [Hammer, G.L., Sinclair, T.R., Boote, K.J., Wright, G.C., Meinke, H., Bell, M.J., 1995. A peanut simulation model. I. Model development and testing. Agron. J. 87, 1085-1093]. The relationship between CO2 and water stress in the experiments and in the models was examined. From a physiological perspective, water-stressed crops are expected to show greater CO2 stimulation than well-watered crops. This expectation has been cited in literature. However, this result is not seen consistently in either the FACE studies or in the crop models. In contrast, leaf-level models of assimilation do consistently show this result. An analysis of the evidence from these models and from the data suggests that scale (canopy versus leaf), model calibration, and model complexity are factors in determining the sign and magnitude of the interaction between CO2 and water stress. We conclude from our study that the statement that 'water-stressed crops show greater CO2 stimulation than well-watered crops' cannot be held to be universally true. We also conclude, preliminarily, that the relationship between water stress and assimilation varies with scale. Accordingly, we provide some suggestions on how studies of a similar nature, using crop models of a range of complexity, could contribute further to understanding the roles of model calibration, model complexity and scale. (C) 2008 Elsevier B.V. All rights reserved.

Building synergies in development research: The application of the mosaic model to animal health research

Development research has responded to a number of charges over the past few decades. For example, when traditional research was accused of being 'top-down', the response was participatory research, linking the 'receptors' to the generators of research. As participatory processes were recognised as producing limited outcomes, the demand-led agenda was born. In response to the alleged failure of research to deliver its products, the 'joined-up' model, which links research with the private sector, has become popular. However, using examples from animal-health research, this article demonstrates that all the aforementioned approaches are seriously limited in their attempts to generate outputs to address the multi-faceted problems facing the poor. The article outlines a new approach to research: the Mosaic Model. By combining different knowledge forms, and focusing on existing gaps, the model aims to bridge basic and applied findings to enhance the efficiency and value of research, past, present, and future.

Results of a mechanistic model estimating methane in relation to methane emissions measured in dairy cows

This investigation determines the accuracy of estimation of methanogenesis by a dynamic mechanistic model with real data determined in a respiration trial, where cows were fed a wide range of different carbohydrates included in the concentrates. The model was able to predict ECM (Energy corrected milk) very well, while the NDF digestibility of fibrous feed was less well predicted. Methane emissions were predicted quite well, with the exception of one diet containing wheat. The mechanistic model is therefore a helpful tool to estimate methanogenesis based on chemical analysis and dry matter intake, but the prediction can still be improved.

Seeds of growth? Agricultural productivity and the transitional dynamics of the Ramsey model

A two-sector Ramsey-type model of growth is developed to investigate the relationship between agricultural productivity and economy-wide growth. The framework takes into account the peculiarities of agriculture both in production ( reliance on a fixed natural resource base) and in consumption (life-sustaining role and low income elasticity of food demand). The transitional dynamics of the model establish that when preferences respect Engel's law, the level and growth rate of agricultural productivity influence the speed of capital accumulation. A calibration exercise shows that a small difference in agricultural productivity has drastic implications for the rate and pattern of growth of the economy. Hence, low agricultural productivity can form a bottleneck limiting growth, because high food prices result in a low saving rate.