Thesis (M.U.D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 60-61) Also available in print.

Thesis (Ph. D.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 109-115). Also available on the World Wide Web.

Thesis (Ph. D.)--Ohio State University, 1987. / Includes vita. Includes bibliographical references (leaves 134-141). Available online via OhioLINK's ETD Center.

Thesis (M.S.)--University of Montana, 2007. / Title from title screen. Description based on contents viewed June 12, 2007. Includes bibliographical references (p. ix-xv).

No description available.

Urbanization and economic development have important implications for many environmental processes including global climate change. Although there is evidence that urbanization depends endogenously on economic variables, long-term forecasts of the spatial distribution of population are often made exogenously and independent of economic conditions. A beta distribution for individual countries/regions is estimated to describe the geographical distribution of population using a 1° x 1° latitude-longitude global population data set. Cross-sectional country/regional data are then used to estimate an empirical relationship between parameters of the beta distribution and macroeconomic variables as they vary among countries/regions. This conditional beta distribution allows the simulation of a changing distribution of population, including the growth of urban areas, driven by economic forecasts until the year 2100. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).

The field of medical image analysis has been rapidly growing for the past two decades. Besides a significant growth in computational power, scanner performance, and storage facilities, this acceleration is partially due to an unprecedented increase in the amount of data sets accessible for researchers. Medical experts traditionally rely on manual comparisons of images, but the abundance of information now available makes this task increasingly difficult. Such a challenge prompts for more automation in processing the images.In order to carry out any sort of comparison among multiple medical images, onefrequently needs to identify the proper correspondence between them. This step allows us to follow the changes that happen to anatomy throughout a time interval, to identify differences between individuals, or to acquire complementary information from different data modalities. Registration achieves such a correspondence. In this dissertation we focus on the unified analysis and characterization of statistical registration approaches.We formulate and interpret a select group of pair-wise registration methods in the context of a unified statistical and information theoretic framework. This clarifies the implicit assumptions of each method and yields a better understanding of their relative strengths and weaknesses. This guides us to a new registration algorithm that incorporates the advantages of the previously described methods. Next we extend the unified formulation with analysis of the group-wise registration algorithms that align a population as opposed to pairs of data sets. Finally, we present our group-wise registration framework, stochastic congealing. The algorithm runs in a simultaneous fashion, with every member of the population approaching the central tendency of the collection at the same time. It eliminates the need for selecting a particular referenceframe a priori, resulting in a non-biased estimate of a digital template. Our algorithm adopts an information theoretic objective function which is optimized via a gradientbased stochastic approximation process embedded in a multi-resolution setting. We demonstrate the accuracy and performance characteristics of stochastic congealing via experiments on both synthetic and real images. / PhD thesis

Texte remanié de: Diss.--Fakultät für Geschichtswissenschaften--Bochum--Ruhr-Universität, 1997. / Bibliogr. p. 449-467. Index.

Ce travail de thèse concerne la modélisation mathématique et l’étude du comportement d’une population de neurones. Dans tout ce travail on s’arrêtera principalement sur une population de neurones auto-excitateurs où chaque cellule du réseau est supposée suivre la loi de l’intègre et tire. Néanmoins nous aborderons au détour d’un chapitre la modélisation d’une population de neurones inhibiteurs, et dans une dernière partie, nous discuterons la modélisation d’une population de neurones obéissant au modèle Ermentrout-Kopell aussi appelé le théta-neurone. L’angle de vue adopté dans cette thèse est donné par l’approche densité de population. Cette approche, dont nous rappellerons en détail les hypothèses et la construction, a été introduite il ya maintenant plus d’une dizaine d’années afin de faciliter la simulation d’une grande population de neurones. Dit plus précisément, une telle approche donne une équation aux dérivées partielles sur la densité de population de neurones dans l’espace d’état formé des potentiels admissibles du neurone. Nous ferons de plus l’hypothèse que la réponse d’un neurone à l’arrivée d’une impulsion est une dépolarisation instantanée, autrement dit un saut de potentiel. Comme nous le verrons,cette équation aux dérivées partielles est non linéaire (à cause du couplage de la population) et non locale (à cause du saut de potentiel). Si cette idée est compliquée et abstraite, elle anéanmoins prouvé tout au long de ces dix dernières années son importance dans la simulation numérique des grands réseaux.Il s’agit avant tout dans ce travail de thèse de donner un cadre mathématique adéquat aux équations aux dérivées partielles qui surgissent d’une telle approche. Ainsi nous discuterons,selon les différents choix de modélisation, du caractère bien posé du modèle par densité de populationet de sa possible explosion en temps fini. Nous discuterons comment la prise en compte d’hypothèses réalistes supplémentaires dans la modélisation, comme le retard entre l’émission d’un potentiel d’action et sa réception ou encore la période réfractaire peut stopper l’explosionen temps fini et garantir l’existence d’une solution globale. Un autre aspect abordé dans ce travail concerne les explications et la prédiction de la synchronisation des neurones. Deux définitions de la synchronisation seront explicitées selon encoreune fois les choix de modélisation. Nous verrons qu’en interprétant l’explosion en temps fini dela solution comme l’arrivée d’une masse de Dirac dans le taux de décharge de la populationon peut relier l’explosion à la synchronisation. Toutefois, avec des hypothèses de modélisation plus réalistes, comme les retards et la période réfractaire, ce phénomène est exclu. Nous verrons néanmoins qu’avec ces paramètres physiques supplémentaires des solutions périodiques apparaissent offrant différents rythmes de décharge de la population. Encore une fois, l’apparition de ces oscillations sera perçue comme la synchronisation de la population. / This thesis concerns the mathematical modelling and the study of the behavior of a population of neurons. In this work we will mainly consider a population of excitatory neurons whe reall the cells of the network follow the integrate-and-fire model. Nonetheless, we will tackle in a chapter the modelling of an inhibitory population of neurons, and we will discuss in the lastchapter the modelling of a population of neurons that follows the Ermentrout-Koppell model.The point of view of this thesis is given by the population density approach that has beenintroduced more than a decade ago in order to facilitate the simulation of a large assembly ofneurons. More precisely, this approach gives a partial differential equation that describes thedensity of neurons in the state space that is the set of all admissible potential of a neuron. We will assume that when receiving an action potential, the potential of the neuron makes a small jump. As we will see this partial differential equation is non linear (due to the coupling betweenneurons) and non-local (due to the potential jump). If this idea is complicated and abstract, itallows to simulate easily a large neural network.First of all, the thesis gives a mathematical framework for the equations that arise from thisthe population density approach. Then we will discuss the existence and the possible blow upin finite time of the solution. We will discuss how the consideration of more realistic modellingassumptions, as the refractory period and the delay between the emission and the reception ofan action potential can stop the blow up of the solution and give a well posed model.We will also try to caracterise the occurence of synchronization of the neural network. Twodifferent ways of seeing the synchronization will be describe. One relates the blow up in finitetime of the solution to the occurence of a Dirac mass in the firing rate of the population.Nonetheless, taking into account the delays, this kind of blow up will not be observed anymore.Nonetheless, as we will see, with this additional features the model will generate some periodicalsolutions that can also be related to the synchronization of the population.

In this study, changes in the social and economic structure of a Northern Thai community are analysed in terms of demographic change. Although primarily an empirical study, it is hoped also to contribute to two associated theoretical problems. The first concerns the relationship between economic and demographic change in the process of social evolution. It is argued that rather than one or other variable being 'independent', such changes are a result of complex interaction between the variables over time. The second stems from the debate on the nature of Northern Thai social structure. Here the value of incorporating an analysis of demographic change in an anthropological study is exemplified by the evidence that apparent inconsistencies and contradictions found in the literature on communities in Northern Thailand can be explained to a large extent by an examination of their individual demographic histories. Fieldwork was conducted in Ban Pong Village in Chiengmai Province of Northern Thailand between 1972 and 1974. Following settlement of the village in the 1880s, the valley was gradually cleared for irrigated rice cultivation by a slowly growing population of migrants. Dominance by a minority of the population of the important local trade in fermented tea in the 1920s and 1930s at a time when land resources in the valley were almost exhausted and economic conditions had forced a number of farmers to sell their land, opened the way to the extreme economic polarization found in the community today. The problems facing the community have been compounded by the rapid growth of population occurring since the early 195os, which is largely the result of a decline in infant mortality. A family planning programme introduced to Ban Pong in 1967 provoked an immediate response, and within two years over 40% of fertile married women were using a modern method of birth control. The concomitant changes in marriage and residence patterns are considered in relation to population growth and fertility control.