Дисертації з теми "SIR Models"
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Abdelsheed, Ismail Gad Ameen. "Fractional calculus: numerical methods and SIR models." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3422267.
Повний текст джерелаАнотація:
Fractional calculus is ”the theory of integrals and derivatives of arbitrary order, which unify and generalize the notions of integer-order differentiation and n-fold integration”. The idea of generalizing differential operators to a non-integer order, in particular to the order 1/2, first appears in the correspondence of Leibniz with L’Hopital (1695), Johann Bernoulli (1695), and John Wallis (1697) as a mere question or maybe even play of thoughts. In the following three hundred years a lot of mathematicians contributed to the fractional calculus: Laplace (1812), Lacroix (1812), Fourier (1822), Abel (1823-1826), Liouville (1832-1837), Riemann (1847), Grunwald (1867-1872), Letnikov (1868-1872), Sonin (1869), Laurent (1884), Heaviside (1892-1912), Weyl (1917), Davis (1936), Erde`lyi (1939-1965), Gelfand and Shilov (1959-1964), Dzherbashian (1966), Caputo (1969), and many others. Yet, it is only after the First Conference on Fractional Calculus and its applications that the fractional calculus becomes one of the most intensively developing areas of mathematical analysis. Recently, many mathematicians and applied researchers have tried to model real processes using the fractional calculus. This is because of the fact that the realistic modeling of a physical phenomenon does not depend only on the instant time, but also on the history of the previous time which can be successfully achieved by using fractional calculus. In other words, the nature of the definition of the fractional derivatives have provided an excellent instrument for the modeling of memory and hereditary properties of various materials and processes.Il calcolo frazionario e` ”the theory of integrals and derivatives of arbitrary order, which unify and generalize the notions of integer-order differentiation and n-fold integration”. L’ idea di generalizzare operatori differenziali ad un ordine non intero, in particolare di ordine 1/2, compare per la prima volta in una corrispondenza di Leibniz con L’Hopital (1695), Johann Bernoulli (1695), e John Wallis (1697), come una semplice domanda o forse un gioco di pensieri. Nei successive trecento anni molti matematici hanno contribuito al calcolo frazionario: Laplace (1812), Lacroix (1812), di Fourier (1822), Abel (1823-1826), Liouville (1832-1837), Riemann (1847), Grunwald (1867-1872), Letnikov (1868-1872), Sonin (1869), Laurent (1884), Heaviside (1892-1912), Weyl (1917), Davis (1936), Erde`lyi (1939-1965), Gelfand e Shilov (1959-1964), Dzherbashian (1966), Caputo (1969), e molti altri. Eppure, è solo dopo la prima conferenza sul calcolo frazionario e le sue applicazioni che questo tema diventa una delle le aree più intensamente studiate dell’analisi matematica. Recentemente, molti matematici e ingegneri hanno cercato di modellare i processi reali utilizzando il calcolo frazionario. Questo a causa del fatto che spesso, la modellazione realistica di un fenomeno fisico non è locale nel tempo, ma dipende anche dalla storia, e questo comportamento può essere ben rappresentato attraverso modelli basati sul calcolo frazionario. In altre parole, la definizione dei derivata frazionaria fornisce un eccellente strumento per la modellazione della memoria e delle proprietà ereditarie di vari materiali e processi.
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Almeida, Priscila Roque de. "Modelos epidêmicos SIR, contínuos e discretos, e estratégias de vacinação." Universidade Federal de Viçosa, 2014. http://locus.ufv.br/handle/123456789/4933.
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Previous issue date: 2014-02-21Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The main Objective Of this Work is to study and discretize the epidemic SIR model (Susceptible-Infected-Recovered) developed by Kermack and MCKendrick in 1927 [11], between its Consider the simple models With Vital dynamics and Constant and Vaccination strategies pulses, as a method Of epidemic ControL The study of the stability of Continuous-time models With pulse Vaccination is done by means of the Floquet theory. Already the rnethod Of ñnite difference appro- Ximation is used to forward discretize Continuous systems and the analysis On the stability of the new systems found is displayed The theoretical results are Conñrmed by numerical simulations.
O Objetivo principal desde trabalho é estudar e discretizar os modelos epidêmi- COS SIR (Suscetíveis-Infectados-Recuperados) desenvolvidos por MCKendrick e Kermack em 1927, [11], entre eles Consideramos os modelos simples Com dinâmica Vital e Com estratégias de Vacinação Constante e em pulsos, Como método de Con- trole epidêmico. O estudo da estabilidade dos modelos em tempo Contínuos Com Vacinação em pulsos é feito por meio, da Teoria de Floquet. Já 0 rnétodo de aproximação de diferenças ñnitas para frente é utilizado para discretizar os siste- mas Contínuos e é apresentada a análise sobre a estabilidade dos novos sistemas encontrados. Os resultados teóricos são Conñrmados por simulações numéricas.
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Estrada, López Mario Andrés 1989. "Teoremas limiares para o modelo SIR estocástico de epidemia." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307035.
Повний текст джерелаАнотація:
Orientador: Élcio LebensztaynDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica
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Resumo: Este trabalho tem como objetivo estudar o modelo SIR (suscetível-infectado-removido) de epidemia nas versões determinística e estocástica. Nosso objetivo é encontrar limitantes para a probabilidade de que o tamanho da epidemia não sobrepasse certa proporção do número inicial de suscetíveis. Iniciamos apresentando as definições e a dinâmica do processo de epidemia determinístico. Obtemos um valor limiar para o número inicial de suscetíveis para que a epidemia exploda ou não. Consideramos o modelo de epidemia estocástico SIR assumindo que não há período latente, isto é, que um infectado pode transmitir a infecção ao instante de ser contagiado. O modelo é considerado com uma configuração inicial de suscetíveis e infectados e é feita especial ênfases no estudo da variável aleatória ''tamanho da epidemia'', que é definida como a diferença entre o número de suscetíveis ao começar e ao terminar a propagação da doença. Como na parte determinística, obtemos teoremas limiares para o modelo de epidemia estocástico. Os métodos usados para encontrar os limitantes são os de análise da cadeia de Markov imersa e de comparação estocástica
Abstract: This work has as objective to study the SIR (susceptible-infected-removed) epidemic model in the deterministic and stochastic version. Our objective is to find bounds for the probability that the size of the epidemic does not exceed certain proportion of the initial number of susceptible individuals. We begin presenting the definitions and the dynamics for the deterministic model for a general epidemic. We obtain a threshold value for the initial number of susceptible individuals for the epidemic to build up or not. As fundamental part of this work, we consider a stochastic epidemic SIR model assuming there is no latent period, that is, one infected can transmit the infection at the moment of being infected. The model is considered with an initial configuration of susceptible and infected individuals and the study is focused on the random variable ''size of the epidemic'', which is defined as the difference between the number of susceptible individuals at the start and at the end of the propagation of the epidemic. As in the deterministic part, we obtain a threshold theorem for the stochastic epidemic. The methods used to prove the theorem are analysis of the embedded chain and the stochastic comparison
Mestrado
Estatistica
Mestre em Estatística
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Medlock, Jan P. "The effect of stochastic migration on an SIR model for the transmission of HIV." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/30547.
Повний текст джерела
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Ozanne, Marie Veronica. "Bayesian compartmental models for zoonotic visceral leishmaniasis in the Americas." Diss., University of Iowa, 2019. https://ir.uiowa.edu/etd/6825.
Повний текст джерелаАнотація:
Visceral leishmaniasis (VL) is a serious neglected tropical disease that is endemic in 98 countries and presents a significant public health risk. The epidemiology of VL is complex. In the Americas, it is a zoonotic disease that is caused by a parasite and transmitted among humans and dogs through the bite of an infected sand fly vector. The infection also can be transmitted vertically from mother to child during pregnancy. Infected individuals can be classified as asymptomatic or symptomatic; both classes can transmit infection. In part due to its complexity, VL transmission dynamics are not fully understood. Stochastic compartmental epidemic models are a powerful set of tools that can be used to study these transmission dynamics.
Past compartmental models for VL have been developed in a deterministic framework to accommodate complexity while remaining computationally tractable. In this work, we propose stochastic compartmental models for VL, which are simpler than their deterministic counterparts, but also have several advantages. Notably, this framework allows us to: (1) define a probability of infection transmission between two individuals, (2) obtain both parameter estimates and corresponding uncertainty measures, and (3) employ formal model comparisons.
In this dissertation, we develop both population level and individual level Bayesian compartmental models to study both vector and vertical VL transmission dynamics. As part of this model development, we introduce a compartmental model that allows for two infectious classes. We also derive source specific reproductive numbers to quantify the contributions of different species and infectious classes to maintaining infection in a population. Finally, we propose a formal model comparison method for Bayesian models with high-dimensional discrete parameter spaces. These models, reproductive numbers, and model comparison method are explored in the context of simulations and real VL data from Brazil and the United States.
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Terefe, Yibeltal Adane. "Bifurcation analysis and nonstandard finite difference schemes for Kermack and McKendrick type epidemiological models." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/24917.
Повний текст джерелаАнотація:
The classical SIR and SIS epidemiological models are extended by considering the number of adequate contacts per infective in unit time as a function of the total population in such a way that this number grows less rapidly as the total population increases. A diffusion term is added to the SIS model and this leads to a reaction–diffusion equation, which governs the spatial spread of the disease. With the parameter R0 representing the basic reproduction number, it is shown that R0 = 1 is a forward bifurcation for the SIR and SIS models, with the disease–free equilibrium being globally asymptotic stable when R0 is less than 1. In the case when R0 is greater than 1, for both models, the endemic equilibrium is locally asymptotically stable and traveling wave solutions are found for the SIS diffusion model. Nonstandard finite difference (NSFD) schemes that replicate the dynamics of the continuous SIR and SIS models are presented. In particular, for the SIS model, a nonstandard version of the Runge-Kutta method having high order of convergence is investigated. Numerical experiments that support the theory are provided. On the other hand the SIS model is extended to a Volterra integral equation, for which the existence of multiple endemic equilibria is proved. This fact is confirmed by numerical simulations.Dissertation (MSc)--University of Pretoria, 2012.
Mathematics and Applied Mathematics
unrestricted
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Tosun, Kursad. "QUALITATIVE AND QUANTITATIVE ANALYSIS OF STOCHASTIC MODELS IN MATHEMATICAL EPIDEMIOLOGY." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/dissertations/732.
Повний текст джерелаАнотація:
We introduce random fluctuations on contact and recovery rates in three basic deterministic models in mathematical epidemiology and obtain stochastic counterparts. This paper addresses qualitative and quantitative analysis of stochastic SIS model with disease deaths and demographic effects, and stochastic SIR models with/without disease deaths and demographic effects. We prove the global existence of a unique strong solution and discuss stochastic asymptotic stability of disease free and endemic equilibria. We also investigate numerical properties of these models and prove the convergence of the Balanced Implicit Method approximation to the analytic solution. We simulate the models with fairly realistic parameters to visualize our conclusions.
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Graf, Brolund Alice. "Compartmental Models in Social Dynamics." Thesis, Uppsala universitet, Avdelningen för systemteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448163.
Повний текст джерелаАнотація:
The dynamics of many aspects of social behaviour, such as spread of fads and fashion, collective action, group decision-making, homophily and disagreement, have been captured by mathematical models. The power of these models is that they can provide novel insight into the emergent dynamics of groups, e.g. 'epidemics' of memes, tipping points for collective action, wisdom of crowds and leadership by small numbers of individuals, segregation and polarisation. A current weakness in the scientific models is their sheer number. 'New' models are continually 'discovered' by physicists, engineers and mathematicians. The models are analysed mathematically, but very seldom provide predictions that can be tested empirically. In this work, we provide a framework of simple models, based on Lotka's original idea of using chemical reactions to describe social interactions. We show how to formulate models for social epidemics, social recovery, cycles, collective action, group decision-making, segregation and polarisation, which we argue encompass the majority of social dynamics models. We present an open-access tool, written in Python, for specifying social interactions, studying them in terms of mass action, and creating spatial simulations of model dynamics. We argue that the models in this article provide a baseline of empirically testable predictions arising from social dynamics, and that before creating new and more complicated versions of the same idea, researchers should explain how their model differs substantially from our baseline models.Matematiska modeller kan hjälpa oss att förstå många typer av sociala fenomen, som ryktesspridning, spridning av memes, gruppbeslut, segregation och radikalisering. Det finns idag otaliga modeller för sociala beteenden hos människor och djur, och fler presenteras kontinuerligt. Det stora antalet modeller försvårar navigering inom forskningsfältet, och många av modellerna är dessutom komplicerade och svåra att verifiera genom experiment. I detta arbete föreslås ett ramverk av grundläggande modeller, som var och en modellerar en aspekt av socialt beteende; det gäller sociala epidemier, cykler, gemensamt handlande, gruppbeslut, segregation och polarisering. Vi menar att dessa modeller utgör majoriteten av de verifierbara aspekter av socialt beteende som studeras, och att de bör behandlas som en utgångspunkt när en ny modell ska introduceras. Vilka av mekanismerna från utgångspunkten finns representerade i modellen? Skiljer den sig ens nämnvärt från utgångspunkten? Genom att ha en god förståelse för grundmodellerna, och genom att förklara på vilket sätt en ny modell skiljer sig från dem, kan forskare undvika att presentera modeller som i praktiken är mer komplicerade varianter av sådana som redan finns. I detta arbete visar vi hur dessa grundläggande modeller kan formuleras och studeras. Modellerna bygger på enkla regler om vad som händer när individer i en befolkning möter varandra. Till exempel, om en person som har vetskap om ett rykte träffar någon som inte har det, kan ryktet spridas vidare. Därför har antaganden om vilka personer som kan träffa varandra stor påverkan på de resultat som modellerna ger. I detta arbete studeras varje modell med två olika metoder: i den ena har alla personer i befolkningen samma sannolikhet att träffa varandra, i den andra representeras befolkningen av ett rutnät, där varje plats motsvarar en individ. I den senare har alltså varje person ett begränsat antal grannar att interagera med. Vilken av dessa två metoder man väljer har stor betydelse för vilka beteenden modellerna förutspår. Som ett komplement till detta arbete presenteras ett verktyg i form av ett Python-program som utför analysen av modellerna. Detta kan användas för att undersöka grundmodellerna som presenteras i detta arbete, men också för att formulera och analysera nya modeller på samma sätt. På det viset kan nya modeller enkelt jämföras mot grundmodellerna. Verktyget är användbart både som introduktion för de som är nya inom social dynamik, men också för de forskare som som vill ta fram nya modeller och föra forskningsfältet vidare.
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Bourdin, Félicien. "Modélisation macroscopique de mouvements de foule à deux types, modèles SIR condensés." Thesis, université Paris-Saclay, 2022. http://www.theses.fr/2022UPASM013.
Повний текст джерелаАнотація:
On étudie dans cette thèse la modélisation macroscopique des mouvements de foule dans le cas d'une population divisée en plusieurs types ayant des comportements différents, ainsi que le développement de modèles d'épidémiologie dits ``SIR'' permettant l'analyse de la propagation d'une maladie infectieuse dans une école. Ces deux problématiques ont été étudiées séparément~: au sujet initial (les mouvements de foule) s'est superposé le problème de modélisation d'épidémie en milieu scolaire suite à une sollicitation de MODCOV19, une plateforme créée par le CNRS et l'INSMI pour centraliser et coordonner les projets de modélisation autour de l'épidémie de COVID-19. Cette thèse est donc composée de deux parties indépendantes. On analyse d'une part la convergence de différents schémas numériques découlant d'approches différentes de l'équation de mouvement de foule à deux types - flot gradient, catching-up, volumes finis. On étudie également l'homogénéisation de modèles microscopiques de particules vers le problème macroscopique. On s'intéresse enfin au problème inverse d'identification des paramètres des modèles étant donnée l'observation d'un mouvement de foule. D'autre part, on développe un type de modèle SIR dit ``condensé'', où les quantités épidémiologiques sont définies à l'échelle de groupes d'individus. On analyse formellement la qualité du processus de condensation lorsque l'on a accès à l'ensemble des interactions dans la population, et on présente l'implémentation effective réalisée en collaboration avec MODCOV19We study in this thesis the macroscopic modelling of crowd motion in the case of a population divided in several types that may have different behaviours, as well as the development of SIR models in order to analyse the spread of an infectious disease in a school. These two issues were studied separetely. As the original topic of this thesis was crowd motion, we answered to a proposition of MODCOV19 - a platform created by CNRS and INSMI to centralize and coordinate modeling projects on the COVID-19 outbreak - to design epidemiological models adapted to school media. This work is thus composed of two independent parts. On the one hand we analyse the convergence of several numerical schemes that stem from different standpoints on the macroscopic crowd motion equation - optimal transport, gradient flow, finite volumes. We study as well the homogenization of microscopic models of particles towards the macroscopic model. We eventually investigate the inverse problem of identifying of the parameters of a model, being observed the motion of a crowd. On the other hand, we develop a class of ``condensed'' SIR models, where the epidemiological quantities are defined at the scale of groups of individuals. We formally analyse the quality of the condensation process when a full description of the interaction within the population is available. We then detail the implementation carried out in collaboration with MODCOV19
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Bouzalmat, Ibrahim. "Modélisation probabiliste de la dynamique de transmission de la fièvre typhoïde à Mayotte avec étude de risques épidémiques." Electronic Thesis or Diss., Université de Montpellier (2022-....), 2023. http://www.theses.fr/2023UMONS064.
Повний текст джерелаАнотація:
Ce manuscrit de thèse vise à étudier la transmission de la fièvre typhoïde à Mayotte en utilisant des approches de modélisation mathématique. Nous introduisons tout d'abord le contexte de notre étude, les problématiques associées et les objectifs de la thèse. Un état de l'art sur la modélisation mathématique de la transmission de la fièvre typhoïde est présenté, mettant en évidence la spécificité de notre approche. Nous proposons un modèle initial en deux versions, déterministe et stochastique, pour décrire la dynamique de transmission de la maladie à Mayotte. Nous explorons le comportement du modèle à travers des simulations numériques dans différents scénarios, en mettant en évidence les facteurs clés de la transmission. Cependant, en raison des limitations du jeu de données disponibles, nous proposons un modèle stochastique simplifié et une méthode d'estimation paramétrique. Cette approche nous permet d'ajuster le modèle aux données disponibles et d'estimer les caractéristiques clés de la transmission de la fièvre typhoïde à Mayotte. En enrichissant notre modèle, nous introduisons de nouvelles extensions. Nous incluons un compartiment pour les individus exposés, prenant en compte la durée d'incubation de la maladie. Les propriétés théoriques de ce modèle sont étudiées et illustrées par des simulations numériques. De plus, nous proposons une méthodologie d'estimation des paramètres adaptée à ce nouveau modèle, et des simulations numériques ont été réalisées pour évaluer la performance de notre approche d'estimation. Nous examinons ensuite l'impact de la pluviométrie sur la transmission de la fièvre typhoïde à Mayotte, en utilisant des données publiques de précipitations. Nous identifions une saisonnalité de la pluie et estimons les paramètres du modèle sous différents régimes. Les résultats soulignent l'importance de cette variable météorologique dans la propagation de l'épidémie.Ce manuscrit ouvre des perspectives de recherche, telles que l'extension du modèle à d'autres maladies infectieuses présentes à Mayotte et sa généralisation à d'autres territoires. Ces travaux contribueront à une meilleure compréhension et gestion des maladies infectieuses à Mayotte et dans d'autres régions similairesThe aim of this thesis manuscript is to study the transmission of typhoid fever in Mayotte using mathematical modelling approaches. We first introduce the context of our study, the associated issues, and the objectives of the thesis. A state-of-the-art review on mathematical modeling of typhoid fever transmission is presented, highlighting the specificity of our approach. We propose an initial model in two versions, deterministic and stochastic, to describe the transmission dynamics of the disease in Mayotte. We explore the behavior of the model through numerical simulations in different scenarios, highlighting key factors of transmission. However, due to the limitations of the available dataset, we propose a simplified stochastic model and a parametric estimation method. This approach enables us to fit the model to the available data and to estimate the key characteristics of typhoid fever transmission in Mayotte. In enriching our model, we are introducing new extensions. We include a compartment for individuals exposed, taking into account the incubation period of the disease. The theoretical properties of this model are studied and illustrated by numerical simulations. In addition, we propose a parameter estimation methodology adapted to this new model, and numerical simulations have been carried out to evaluate the performance of our estimation approach. We then examine the impact of rainfall on the transmission of typhoid fever in Mayotte, using publicly available precipitation data. We identify rainfall seasonality and estimate model parameters under different regimes. The results highlight the importance of this meteorological variable in the spread of the epidemic.This manuscript opens up research perspectives, such as the extension of the model to other infectious diseases present in Mayotte and its generalisation to other territories. This work will contribute to a better understanding and management of infectious diseases in Mayotte and other similar regions
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Fröberg, Tobias, and Ludwig Nordström. "Adaptive SIR-models’ Ability to Both Estimate the Reproduction Number and Forecast the Future Spread of Covid-19 in Sweden." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302493.
Повний текст джерелаАнотація:
In outbreaks like the Covid-19 pandemic, mathematical models can be used to estimate various epidemiological parameters which model the evolution of the disease. A popular model that is used by Folkhälsomyndigheten (FHM) for estimating the effective reproduction number (Rt) has the shortcoming that it cannot simultaneously forecast the future number of cases. This thesis explores an extension of another model, the SIR-model, in which the model parameters are fitted to recorded data. This makes the model adaptive, opening up the possibilities for estimating the Rt daily and making predictions of future number of confirmed cases. The thesis use this adaptive SIR-model (aSIR) to estimate the Rt and create forecasts of new cases in Sweden. The thesis’ purpose is to determine how precise aSIR-models are at estimating the Rt (when compared with FHM’s model). It will also analyze how accurate aSIR-models are at simultaneously forecasting the future spread of Covid-19 in Sweden. The results of this thesis showed an aSIR-model is good at estimating the Rt, with a similar precision when compared to the Rt estimated by FHM’s method. The aSIR-model also quickly adapted to sudden changes and dynamics during the outbreak in a similar way to that of the method used by FHM. When used as a tool for forecasting, the aSIR-model performed well for shorter time periods or when the Rt had a low variance. For longer time periods or when the Rt varied a lot, the forecast accuracy fell significantly.
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Hussaini, Nafiu. "Mathematical modelling and analysis of HIV transmission dynamics." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/5672.
Повний текст джерелаАнотація:
This thesis firstly presents a nonlinear extended deterministic Susceptible-Infected (SI) model for assessing the impact of public health education campaign on curtailing the spread of the HIV pandemic in a population. Rigorous qualitative analysis of the model reveals that, in contrast to the model without education, the full model with education exhibits the phenomenon of backward bifurcation (BB), where a stable disease-free equilibrium coexists with a stable endemic equilibrium when a certain threshold quantity, known as the effective reproduction number (Reff ), is less than unity. Furthermore, an explicit threshold value is derived above which such an education campaign could lead to detrimental outcome (increase disease burden), and below which it would have positive population-level impact (reduce disease burden in the community). It is shown that the BB phenomenon is caused by imperfect efficacy of the public health education program. The model is used to assess the potential impact of some targeted public health education campaigns using data from numerous countries. The second problem considered is a Susceptible-Infected-Removed (SIR) model with two types of nonlinear treatment rates: (i) piecewise linear treatment rate with saturation effect, (ii) piecewise constant treatment rate with a jump (Heaviside function). For Case (i), we construct travelling front solutions whose profiles are heteroclinic orbits which connect either the disease-free state to an infected state or two endemic states with each other. For Case (ii), it is shown that the profile has the following properties: the number of susceptible individuals is monotone increasing and the number of infectives approaches zero, while their product converges to a constant. Numerical simulations are shown which confirm these analytical results. Abnormal behavior like travelling waves with non-monotone profile or oscillations are observed.
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Porter, Rosalyn. "Mathematical models of a tick borne disease in a British game bird with potential management strategies." Thesis, University of Stirling, 2011. http://hdl.handle.net/1893/3039.
Повний текст джерелаАнотація:
Louping ill virus (LIV) is a tick borne disease that causes mortality in red grouse, an economically important game bird of British uplands. The aim of this thesis is to extend previously published models of LIV , to consider the potential impact of different management strategies. In addition a new route of infection and the seasonal biology of both grouse and ticks will be explored. Grouse chicks are known to eat ticks as part of their diet in the first three weeks of life which may contribute to virus persistence if chicks consume infected ticks. This novel route of infection is incorporated in to the model which predicts that ingestion increases the range of host densities for which the virus is able to persist. The ingestion of ticks by grouse also reduces the tick population so that for low host densities the ingestion of ticks by grouse reduces the tick population so virus cannot persist. The model is adapted to take account of the seasonal biology of grouse and ticks. Although the temporal predictions of the seasonal models show some differences the addition of seasonality does not alter the model predictions of when LIV is likely to persist at different grouse and deer densities. Consequently seasonality is felt to be unimportant when considering management strategies. The treatment of sheep with acaricide in an attempt to reduce the tick population on a grouse moor is currently being trialled in Scotland. We use a model to predict the likely effect of this strategy at different deer densities. The number of ticks found attached to sheep varies so we consider the effect of tick attachment rates as well as acaricide efficacy. Although we predict that acaricide treated sheep can reduce the tick population and therefore LIV in grouse in some circumstances the treatment is less effective in the presence of deer. Consequently we use a model to make theoretical predictions of the effectiveness of acaricide treated deer as a control strategy for reducing LIV in red grouse. The effect of culling deer on LIV in grouse is also modelled and contrasted with the effect of acaricide use. It is predicted that acaricide treatment of deer could be highly effective, particularly if the deer density is first reduced by culling. Finally we considered the direct treatment of red grouse with acaricide. Female grouse can be given an acaricidal leg band which protects her directly and indirectly protects her chicks as they acquire some acaricide whilst brooding. Trials have suggested this can reduce tick burdens for individuals. We use the model to determine the potential effect that treating individual broods may have on the whole grouse population. The model predictions suggest that unless acaricide efficacy on chicks is high and long lasting treating individual broods is unlikely to reduce LIV in the whole population but will still provide some benefit for the individuals. The effectiveness of treatment is reduced by higher deer densities. The success of the management strategies considered in this thesis appear to be restricted by the presence of deer. It may therefore be that a combination of treatments including the treatment of deer may be of the greatest benefit to the grouse population.
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Siddiqui, Sameeha Qaiser. "Backward bifurcation in SIR endemic models : this thesis is presented in partial fulfillment of the requirements for the degree of Masters of Information Science in Mathematics at Massey University, Albany, Auckland, New Zealand." Massey University, 2008. http://hdl.handle.net/10179/929.
Повний текст джерелаАнотація:
In the well known SIR endemic model, the infection-free steady state is globally stable for R0 < 1 and unstable for R0 > 1. Hence, we have a forward bifurcation when R0 = 1. When R0 > 1, an asymptotically stable endemic steady state exists. The basic reproduction number R0 is the main threshold bifurcation parameter used to determine the stability of steady states of SIR endemic models. In this thesis we study extensions of the SIR endemic model for which a backward bifurcation may occur at R0 = 1. We investigate the biologically reasonable conditions for the change of stability. We also analyse the impact of di erent factors that lead to a backward bifurcation both numerically and analytically. A backward bifurcation leads to sub-critical endemic steady states and hysteresis. We also provide a general classi cation of such models, using a small amplitude expansion near the bifurcation. Additionally, we present a procedure for projecting three dimensional models onto two dimensional models by applying some linear algebraic techniques. The four extensions examined are: the SIR model with a susceptible recovered class; nonlinear transmission; exogenous infection; and with a carrier class. Numerous writers have mentioned that a nonlinear transmission function in relation to the infective class, can only lead to a system with an unstable endemic steady state. In spite of this we show that in a nonlinear transmission model, we have a function depending on the infectives and satisfying certain biological conditions, and leading to a sub-critical endemic equilibriums.
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Silva, Renato Aparecido Pimentel da. "Emprego de redes complexas no estudo das relações entre morfologia individual, topologia global e aspectos dinâmicos em neurociência." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-21082012-151906/.
Повний текст джерелаАнотація:
A teoria de redes complexas se consolidou nos últimos anos, graças ao seu potencial como ferramenta versátil no estudo de diversos sistemas discretos. É possível enumerar aplicações em áreas tão distintas como engenharia, sociologia, computação, linguística e biologia. Tem merecido atenção, por exemplo, o estudo da organização estrutural do cérebro, tanto em nível microscópico (em nível de neurônios) como regional (regiões corticais). Acredita-se que tal organização visa otimizar a dinâmica, favorecendo processos como sincronização e processamento paralelo. Estrutura e funcionamento, portanto, estão relacionados. Tal relação é abordada pela teoria de redes complexas nos mais diversos sistemas, sendo possivelmente seu principal objeto de estudo. Neste trabalho exploramos as relações entre aspectos estruturais de redes neuronais e corticais e a atividade nas mesmas. Especificamente, estudamos como a interconectividade entre o córtex e o tálamo pode interferir em estados de ativação do último, considerando-se o sistema tálamo-cortical do gato bem como alguns modelos para geração de rede encontrados na literatura. Também abordamos a relação entre a morfologia individual de neurônios e a conectividade em redes neuronais, e consequentemente o impacto da forma neuronal em dinâmicas atuando sobre tais redes e a eficiência das mesmas no transporte de informação. Como tal eficiência pode ter como consequência a facilitação de processos maléficos às redes, como por exemplo, ataques causados por vírus neurotrópicos, também exploramos possíveis correlações entre características individuais dos elementos que formam as redes complexas e danos causados por processos infecciosos iniciados nos mesmos.Complex network theory has been consolidated along the last years, owing to its potential as a versatile framework for the study of diverse discrete systems. It is possible to enumerate applications in fields as distinct as Engineering, Sociology, Computing, Linguistics and Biology, to name a few. For instance, the study of the structural organization of the brain at the microscopic level (neurons), as well as at regional level (cortical areas), has deserved attention. It is believed that such organization aims at optimizing the dynamics, supporting processes like synchronization and parallel processing. Structure and functioning are thus interrelated. Such relation has been addressed by complex network theory in diverse systems, possibly being its main subject. In this thesis we explore the relations between structural aspects and the activity in cortical and neuronal networks. Specifically, we study how the interconnectivity between the cortex and thalamus can interfere in activation states of the latter, taking into consideration the thalamocortical system of the cat, along with networks generated through models found in literature. We also address the relation between the individual morphology of the neurons and the connectivity in neuronal networks, and consequently the effect of the neuronal shape on dynamic processes actuating over such networks and on their efficiency on information transport. As such efficiency can consequently facilitate prejudicial processes on the networks, e.g. attacks promoted by neurotropic viruses, we also explore possible correlations between individual characteristics of the elements forming such systems and the damage caused by infectious processes started at these elements.
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Doig, Camino Elizabeth. "Un análisis del Teorema del umbral de Peter Whittle para la epidemia general estocástica." Pontificia Universidad Católica del Perú, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/97238.
Повний текст джерелаАнотація:
En la presente exposición se pretende establecer una comparación entre el teorema del umbral de Kermack y McKendrick correspondiente a un modelo epidémico determinístico y el teorema del umbral de Peter Whittle diseñado para un modelo epidémico estocástico.
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Pachas, Manrique Anna Patricia. "Modelos epidemiológicos em redes." reponame:Repositório Institucional do FGV, 2016. http://hdl.handle.net/10438/18662.
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The speed and comprehensiveness global level with the pathogen has spread in recent years has drawn attention to the importance of the contact’s social network structure. In fact, the topology of the networks in which members of society interact has influenced the dynamics of epidemics. Studies have shown that pathogens when disiparem in scale-free networks have different effects when compared broadcast in random networks, such as the classic models. In these there were epidemic threshold, may somehow the health ministry have a control on the dissipation of diseases by applying certain measures such as vaccines. Already in models in which are considered the networks, specifically the free network scale, the threshold disappears. Thus, the epidemic threshold depends on the topology is required to include within this structure models Because of the importance of these networks, random networks and scalefree have been implemented along the epidemics of propagation models to check the epidemic threshold and the characteristic time, noting that the epidemic threshold disappears
A velocidade e a abrangência a nível mundial com que os agentes patogênicos tem se disseminado nos últimos anos tem chamado a atenção para a importância da estrutura da rede social de contato . De fato, a topologia das redes na qual os membros da sociedade interagem têm influenciado na dinâmica das epidemias.Estudos têm demostrado que os agentes patogênicos ao se dissiparem em redes livres de escala tem efeitos diferentes se comparado quando difundidos em redes aleatórias, como nos modelos clássicos. Nestes existiam limiar de epidemia ,podendo de alguma forma as entidades de saúde ter um controle sobre a dissipação das enfermidades , aplicando certas medidas como as vacinas por exemplo. Já nos modelos nos quais são consideradas as redes , especificamente a rede livre de escala,este limiar desaparece. Desta forma, o limiar de epidemia ao depender da topologia se faz necessário incluir esta estrutura dentro dos modelos epidemiológicos. Devido a importância destas redes , redes aleatórias e principalmente redes livres de escala foram implementadas junto a modelos de propagação de epidemias para verificar o limiar de epidemia e o tempo característico , verificando que o limiar de epidemia desaparece.
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MELLO, Renato Francisco Lopes. "Um modelo epidemiológico SIR com estrutura etária." Universidade Federal de Pernambuco, 2009. https://repositorio.ufpe.br/handle/123456789/7119.
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Previous issue date: 2009Conselho Nacional de Desenvolvimento Científico e Tecnológico
Estudaremos a existência e unicidade de soluções e o fenômeno de bifurcação para um modelo epidemiológico SIR com estrutura etária e transmissão dependente da idade. Formularemos o modelo como um sistema de equações diferenciais parciais munido de condições de contorno e a seguir o reformularemos como um problema de Cauchy semilinear abstrato em um espaço de Banach adequado, como o objetivo de demonstrar a existência e unicidade. Então trataremos da existência e unicidade de estados estacionários não-triviais, aplicando uma generalização da teoria de Perron- Frobenius
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Umar, Abdulkarim Mallam. "Stochastic SIR household epidemic model with misclassification." Thesis, University of Kent, 2016. https://kar.kent.ac.uk/62476/.
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Oliveira, Isabel Mesquita de. "Modelos epidemiológicos SEIR." Master's thesis, Porto : Universidade do Porto, Faculdade de Ciências, Departamento de Matemática Pura, 2008. http://hdl.handle.net/10216/64154.
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Oliveira, Isabel Mesquita de. "Modelos epidemiológicos SEIR." Dissertação, Porto : Universidade do Porto, Faculdade de Ciências, Departamento de Matemática Pura, 2008. http://catalogo.up.pt/F?func=find-b&local_base=FCB01&find_code=SYS&request=000098626.
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Ierache, Jorge Salvador. "Modelo de ciclo de vida para el aprendizaje basado en compartición de conocimientos en sistemas autónomos de robots." Editorial de la Universidad Nacional de La Plata (EDULP), 2012. http://hdl.handle.net/10915/18378.
Повний текст джерелаАнотація:
El propósito de esta tesis es formular el modelo de ciclo de vida de aprendizaje de sistemas autónomos de robots, la colaboración desde un sistema autónomo de robot, que se encuentra en un estado de evolución superior en el contexto del ciclo de vida propuesto, a un sistema autónomo de robot receptor, explorar una arquitectura para sistemas autónomos de robots (SARs) con un nuevo módulo de planificación en relación a los trabajos de autores anteriores. La colaboración entre sistemas autónomos de robots se debe considerar en el marco de los trabajos anteriores, comenzando Fritz W, el que considera un sistema autónomo inteligente representado por un robot con un planificador clásico, al que García Martínez R, le incorpora la ponderación de planes y mutación de teorías similares, luego Maceri P, incorpora el intercambio de teorías. Sobre estas bases resulta conveniente considerar la extensión y experimentación de mecanismos de colaboración entre SARs en el marco de un ciclo de vida de aprendizaje, donde SARs más evolucionado colaboran con SARs receptores menos evolucionados. Se presenta un modelo y la arquitectura para un ambiente de múltiples sistemas autónomos de robots, experimentándose la actuación del SAR en el marco de la propuesta. Finalmente, considerando que existen propuestas anteriores enunciadas en el marco de sistemas autónomos de robots, resulta necesario la comparación en términos del rendimiento del aprendizaje del sistema autónomo de robot (SAR), entre las propuestas de autores anteriores las que consideran la planificación, ponderación de planes, métodos de mutación de teorías e intercambio de teorías entre SAR y la propuesta de sumar el mecanismo de colaboración para un SAR.Tesis doctoral de la Facultad de Informática (UNLP). Grado alcanzado: Doctor en Ciencias Informáticas. Director de tesis: Armando De Giusti; co-director: Ramón García Martínez.
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Razavi, H. Ali. "Identification and control of grinding processes for intermetalic [sic] compunds [sic]." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/18917.
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Manfredini, Rodrigo Bonato. "Estimação bayesiana e por maxima verossimilhança de modelos SIR estocasticos." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/305849.
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Orientador: Luiz Koodi HottaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
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Resumo: Os modelos compartimentais têm sido amplamente utilizados para modelar epidemias. Vários métodos têm sido propostos na literatura para estimar os modelos, sendo os mais aplicados, estimadores pelo método de mínimos quadrados, estimadores de máxima verossimilhança e estimadores bayesianos baseados em simulação de Monte Carlo. Na maioria dos casos reais, os dados são apenas parcialmente observáveis. O trabalho considera o caso em que todos os dados são observados e o caso em que apenas os tempos de remoção são disponíveis. As propriedades amostrais dos estimadores de máxima verossimilhança e dos estimadores Bayesianos para dados completos e incompletos são investigadas através de simulação.
Abstract: Compartmental models have been widely used in order to model epidemics. Several methods have been proposed in the literature to estimate the models, specially, the least squares method, maximum likelihood estimation and Bayes estimators based on Monte Carlo simulation. In the most of real cases, the data are only partially observable. The work considers the case that all the data are observed and the case that only the removal times are available. The sampling properties of the maximum likelihood and Bayes estimators for complete and incomplete data are investigated through simulation.
Mestrado
Inferencia
Mestre em Estatística
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Diniz, Márcio Augusto. "Modelos SEIR com taxa de remoção não homogênea." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307312.
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Orientadores: Jorge Alberto Achcar, Luiz Koodi HottaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica
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Resumo: A modelagem matemática de epidemias apresenta grande relevância para a área de epidemiologia por possibilitar uma melhor compreensão do desenvolvimento da doença na população e permitir analisar o impacto de medidas de controle e erradicação. Neste contexto, os modelos compartimentais SEIR (Suscetíveis - Expostos - Infectantes - Removidos) que foram introduzidos por Kermarck e Mckendrick (1927 apud YANG, 2001, Capítulo 1) são extremamente utilizados. Esta dissertação discute o modelo SEIR encontrado em Lekone e Finkenstädt (2006) que considera a introdução das medidas de intervenção na taxa de contato entre suscetíveis e infectantes, e é aplicado aos dados parcialmente observados da epidemia de febre hemorrágica Ebola, ocorrida no Congo em 1995, através de métodos bayesianos. Em uma segunda etapa, o modelo é modificado a fim de considerar a introdução das medidas de intervenção também na taxa de remoção. A utilização da taxa de remoção não homogênea permite uma quantificação do impacto das medidas de intervenção mais próxima da realidade. Além disso, nos dois modelos considerados, uma análise da incerteza gerada pela observação parcial dos dados e uma análise de sensibilidade da escolha das distribuições a priori são realizadas a partir de simulações. E também, é apresentada uma discussão sobre erros de especificação da taxa de remoção Por fim, os dois modelos são aplicados aos dados da epidemia de febre hemorrágica Ebola e os resultados são discutidos
Abstract: Mathematical modeling of epidemics has great relevance to the area of epidemiology by enabling a better understanding of the development of the disease in the population and allow the analysis of the impact of eradication and control measures. In this context, SEIR (Susceptible-Exposed-Infectious-Removed) compartmental models that were introduced by Kermarck e Mckendrick (1927 apud YANG, 2001, Chapter 1) are extremely used. This essay discusses the SEIR model found in Lekone e Finkenstädt (2006) that considers the introduction of intervention measures in the contact rate between susceptible and infectious, and is applied to data partially observed the outbreak of Ebola hemorrhagic fever in Congo, held in 1995, by Bayesian methods. In a second step, the model is modified in order to consider the introduction of intervention measures in the removal rate. The use of time in-homogeneous removal rate allows quantification of the impact of intervention measures closer to reality. In addition, both models considered, an analysis of uncertainty generated by partial observation and a sensitivity analysis of the choice of a priori distributions are made from simulations. And also, a discussion about errors of removal rate specification. Finally, the two models are applied to the data of Ebola hemorrhagic fever epidemic and the results are discussed
Mestrado
Métodos Estatísticos
Mestre em Estatística
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Bataineh, Mohammad Saleh, University of Western Sydney, of Science Technology and Environment College, and of Science Food and Horticulture School. "Stochastic systems : models and polices [sic]." THESIS_CSTE_SFH_Bataineh_M.xml, 2001. http://handle.uws.edu.au:8081/1959.7/622.
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In a multi-server system, probability distributions and loss probabilities for customers arriving with different priority categories are studied. Customers arrive in independent Poisson streams and their service times are exponentially distributed, with different rates for different priorities. The non-queuing customers will be lost if the capacity is fully occupied. In these systems, particularly for higher priority customers, the reduction of the loss probabilities is essential to guarantee the quality of the service. Four different policies for high and low priorities were introduced utilizing the fixed capacity of the system, producing different loss probabilities. The same policies were introduced in the case of a low priority being placed in the queue when the system is fully occupied. An application to the Intensive Care and Coronary Care Unit in Campbelltown Public Hospital in Sydney was introduced. This application analyses the admission and discharge by using queuing theory to develop a model which predicts the proportion of patients from each category that would be prematurely transferred as a function of the size of the unit, number of categories, mean arrival rates, and length of stay.Master of Science (Hons)
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Bataineh, Mohammad Saleh. "Stochastic systems : models and polices [sic] /." View thesis View thesis, 2001. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030724.135734/index.html.
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Thesis (M.Sc. (Hons.)) -- University of Western Sydney, 2001."A thesis presented to the University of Western Sydney in partial fulfilment of the requirements for the degree of Master of Science" Bibliography : leaves 65-69.
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Lora, Marissa Rose. "Modeling Alcohol Abuse Patterns in Hispanic-American Populations Using an SIR Model." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1302641058.
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Gustafsson, Magnus. "Evaluation of StochSD for Epidemic Modelling, Simulation and Stochastic Analysis." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-426227.
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Classical Continuous System Simulation (CSS) is restricted to modelling continuous flows, and therefore, cannot correctly realise a conceptual model with discrete objects. The development of Full Potential CSS solves this problem by (1) handling discrete quantities as discrete and continuous matter as continuous, (2) preserving the sojourn time distribution of a stage, (3) implementing attributes correctly, and (4) describing different types of uncertainties in a proper way. In order to apply Full Potential CSS a new software, StochSD, has been developed. This thesis evaluates StochSD's ability to model Full Potential CSS, where the points 1-4 above are included. As a test model a well-defined conceptual epidemic model, which includes all aspects of Full Potential CSS, was chosen. The study was performed by starting with a classical SIR model and then stepwise add the different aspects of the Conceptual Model. The effects of each step were demonstrated in terms of size and duration of the epidemic. Finally, the conceptual model was also realised as an Agent Based Model (ABM). The results from 10 000 replications each of the CSS and ABM models were compared and no statistical differences could be confirmed. The conclusion is that StochSD passed the evaluation.
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Balkew, Teshome Mogessie. "The SIR Model When S(t) is a Multi-Exponential Function." Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etd/1747.
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The SIR can be expressed either as a system of nonlinear ordinary differential equations or as a nonlinear Volterra integral equation. In general, neither of these can be solved in closed form. In this thesis, it is shown that if we assume S(t) is a finite multi-exponential, i.e. function of the form S(t) = a+ ∑nk=1 rke-σkt or a logistic function which is an infinite-multi-exponential, i.e. function of the form S(t) = c + a/b+ewt, then we can have closed form solution. Also we will formulate a method to determine R0 the basic reproductive rate of an infection.
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Oliveira, Alarcon Matos de. "Mapeamento de áreas suscetíveis a inundação por rompimento de barragem em ambiente semiárido." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-09032017-114124/.
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Barragens pode ser considerando como risco potencial, o conhecimento da forma provável que se comportaria uma onda de cheia (escoamento crítico), provocado pelo rompimento de barragem é muito importante para as populações que residem à jusante do barramento, como acontece em São José do Jacuípe. Isto por que em caso de rompimento torna-se necessário existir plano de evacuação para área afetada a jusante. Neste sentido destaca-se a utilização de modelos ambientais aliados ao SIG como eficaz ferramenta que possibilita mapear áreas com susceptibilidade a inundação em caso de rompimento. O HEC-RAS surge como poderoso modelo hidrológico capaz de efetuar o modelo para rompimento de barragem em integração com o Sistema de Informação Geográfica. E para classificar o grau de risco da população a jusante é fundamental a adoção de metodologia que contemple as variáveis inerentes à importância deste empreendimento, por tanto será utilizado à metodologia de Menescal (2001) por abarcar todas as facetas importantes de segurança de barragem.Dams can be considering as a potential risk, knowledge of probable way to behave a flood wave (critical flow) caused by dam break is very important for people living on the bus downstream, as in São José do Jacuípe. This is because in case of breakage becomes necessary to have the evacuation plan for the downstream affected area. In this sense there is the use of environmental models combined with GIS as an effective tool that makes it possible to map areas with susceptibility to flooding in the event of disruption. The HEC-RAS comes as powerful hydrological model able to make the model for dam breaking in integration with Geographic Information System. And to classify the degree of risk of downstream population is essential to adopt methodology that considers the variables inherent importance of this project for both will be used to Menescal methodology (2001) to cover all the important facets of dam safety.
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Vereen, Kalimah. "An SCIR Model of Meningococcal Meningitis." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/710.
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A model for meningitis is developed by adding a class of carriers to the basic SIR model. This model is used to analyze the impact a vaccination program can have on the health of the population of epidemic prone countries. Analysis of the model shows the local stability of the disease free equilibrium, the existence of an endemic equilibrium and computation of the reproduction number, ℜ0 . Using a MATLAB program we simulate a time course of the model using parameters gathered from the World Health Organization. The numerical solution demonstrates that our reproduction number was correct. We thenconcluded that a high infection transmission rate requires a high vaccine rate.
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Nieto, Melgarejo Herminio. "Comparación de modelos hidrológicos precipitación-escorrentía determinísticos conceptuales con y sin uso de modelo estocástico." Universidad Nacional de Ingeniería. Programa Cybertesis PERÚ, 2007. http://cybertesis.uni.edu.pe/uni/2007/nieto_mh/html/index-frames.html.
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La tesis presenta la aplicación de tres modelos hidrológicos precipitación-escorrentía: TANQUE, NAM, SMA trabajados en la cuenca del río Cañete durante el periodo del primero de agosto de 1973 al primero de abril de 1976; los cuales fueron calibrados (del 01/08/1973 al 31/07/1974), simulados (del 01/08/1974 al 31/07/1975) y validados (del 01/08/1975 al 01/04/1976), posteriormente a estos tres modelos se les agrego modelos estocástico para mejorar la aproximación, es así que primero se agrego un modelo autoregresivo AR(1), y después se aplico el filtro de Kalman. La metodología para evaluar una mejor aproximación, con los datos reales y calculados por las diferentes variantes de los modelos, fue el uso de índices, para la tesis estos son la raíz del error cuadrático normalizado, el índice de eficiencia y el error medio normalizado, obteniéndose resultados satisfactorios para los modelos TANQUE y NAMThis thesis presents the application of three watershed hydrological models: TANK, NAM, SMA performed in Cañete river basin from August 1, 1973 to April 1, 1976; which were calibrated (from 08/01/1973 to 07/31/1974), simulated ( from 01/08/1974 to 31/07/1975) and validated (from 01/08/1975 to 01/04/1976), after that stochastic models were joined to the three models in order to improve the accounting, therefore, first, an AR autoregressive model (1) was joined and then the Kalman filter was applied. The method to assess the best accounting with the real data calculated by the diverse models was to use the indexes - i.e., for the purposes of this thesis, they are the normalizad square error root- the efficiency index and the normalized mean error so satisfactory results on TANK and NAM models were obtained
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Henry, Courtney. "Population Based Model of Gonorrhea and Interventions Against Increased Antibiotic Resistance." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2784.
Повний текст джерелаАнотація:
Gonnorrhea is an infectious sexually transmitted disease (STD) caused by the bacterium Neisseria gonorrhoeae that commonly reproduces in the reproductive tract.The Centers of Disease Control and Prevention (CDC) estimate that more than 700,000 individuals in the U.S. contract new gonorrheal infections per year. During recent years, there has been a progressive global increase of drug-resistant strains of gonorrhea. Therefore, there exists the necessity for health organizations to encourage the monitoring, research and development of innovative treatment regimens. We have developed multiple mathematical models to explore the gonorrheal disease state. The first objective of model formulation was to fit the model to established disease and population data provided by the CDC and U.S. Census Bureau and then include the presence of antibiotic resistance in the model. Additionally, we discuss intervention methods to combat this resistance. The second objective of model formulation was to use parameter sensitivity to determine specific age groups to target in effort to alter disease dynamics.
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Buchhaupt, Christopher. "Model Improvement for SAR Altimetry." Phd thesis, Schriftenreihe Fachrichtung Geodäsie der Technischen Universität Darmstadt, 2019. https://tuprints.ulb.tu-darmstadt.de/9015/1/PhD_Buchhaupt.pdf.
Повний текст джерелаАнотація:
During the last decades Radar altimetry became an important tool to observe the sea surface with respect to sea level and sea state. Since the launch of CryoSat-2 a new technique called SAR altimetry improves the signal to noise ration of retrieved geophysical parameters and due to the smaller along track footprint a better performance in coastal zones is reached. In the last years several new processing modes were developed and tested to improve the understanding of this new technique such as reduced SAR (RDSAR), low resolution mode including range cell migration correction (LRMC) and fully focused SAR processing. The scope of this work is to improve the retrieval of geophysical parameters by developing a new stack and waveform model capable of including more general sea surface representations such as the geoid and introducing vertical wave particle motions. This new model will be included in different retracking schemes to investigate how the retrieved geophysical parameters change with respect to accuracy and precision.
It is shown that 20 Hz SAR processing, which is used in the official level two data products, results in an aliasing of the sea surface and that a surface sampling rate of 40 Hz will yield a lower pink noise floor and more precise retrieved parameters whereas the other two considered processing modes RDSAR and LRMC do not benefit from a higher sampling rate.
Another contribution of this work is the investigation of possible effects of sea surface slopes and curvatures on RDSAR, LRMC and unfocused SAR processing. It can be concluded that the impact of these quantities is small in RDSAR and SAR processing whereas in LRMC processing significant wave height biases up to three metre and sea level biases between minus twenty and plus twenty centimetres can occur if the surface slopes and curvatures are not considered correctly in the signal processing and parameter retrieval process. On the other hand LRMC is capable of estimating geophysical parameters consistent to the other two considered processing modes with a better precision as unfocused SAR.
In the last part it will be shown that the standard deviation of vertical wave particle velocities is an estimable parameter with a high correlation with respect to model and in-situ data. Additionally considering this geophysical parameter in the retracking can lead to consistent wave height estimations with RDSAR at high sea states which was an open issue as mean differences up to twenty centimetres occurred between these two processing modes. However, at small sea states the accuracy is not good due to differences in significant wave height up to one metre and sea level differences up to seven centimetres. This means that there is still a need for further improvements within zero to two metres significant wave heights which needs to be addressed in further studies.
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Gerardi, Davi de Oliveira. "Previsão de séries temporais epidemiológicas usando autômatos celulares e algoritmos genéticos." Universidade Presbiteriana Mackenzie, 2010. http://tede.mackenzie.br/jspui/handle/tede/1386.
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Previous issue date: 2010-08-02SIS (susceptible-infected-susceptible) and SIR (susceptible-infectedremoved) epidemiological models based on probabilistic cellular automaton (PCA) are used in order to simulate the temporal evolution of the number of people infected by dengue in the city of Rio de Janeiro in 2007, and to predict the cases of infection in 2008. In the PCA, three different sizes of lattices and two kinds of neighborhoods are utilized, and each time step of simulation is equivalent to one week of real time. A genetic algorithm (GA) is employed to identify the probabilities of the state transition S→I, in order to reproduce the historical series of 2007 related to this disease propagation. These probabilities depend on the number of infected neighbors. Time-varying and constant probabilities are taken into account. These models based on PCA and GA were able of satisfactorily fitting the data from 2007 and making a good prediction for 2008 (mainly about the total number of cases registered during 2008).
Usam-se modelos epidemiológicos SIS (suscetível-infectado-suscetível) e SIR (suscetível-infectado-removido) baseados em autômato celular probabilista (ACP) a fim de simular a evolução temporal do número de pessoas infectadas por dengue, na cidade do Rio de Janeiro em 2007, e de prever os casos de infecção em 2008. No ACP, utilizam-se reticulados de três tamanhos diferentes e dois tipos de vizinhanças, e cada passo de tempo da simulação equivale a uma semana de tempo real. Emprega-se um algoritmo genético (AG) para identificar os valores das probabilidades da transição de estados S→I, de modo a reproduzir a série histórica de 2007 relacionada à propagação dessa doença. Essas probabilidades dependem do número de vizinhos infectados. Probabilidades variantes e invariantes no tempo são consideradas. Esses modelos baseados em ACP e AG foram capazes de fazer um ajuste satisfatório dos dados de 2007 e de fornecerem uma boa previsão para 2008, (principalmente no que diz respeito ao número total de casos registrados em 2008).
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Marcos, Mejía Luis Miguel. "Estudio cualitativo y dinámico del modelo matemático SIR planteado por Kermack y Mckendrick." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2021. https://hdl.handle.net/20.500.12672/17202.
Повний текст джерелаАнотація:
En este trabajo de tesis, consideramos básicamente el sistema de EDO SIR planteado
por Kermack y McKendrick (ver formula en al interior de la tesis). El objetivo de este trabajo es estudiar cualitativamente el flujo de este sistema. Además se presentan aplicaciones en la vida real.Perú. Universidad Nacional Mayor de San Marcos. Vicerrectorado de Investigación y Posgrado. Programa de Promoción de Tesis de Pregrado. E18030044-PTPGRADO
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Tsui, Hong P. "Turbulent premixed combustion simulation with Conditional Source-term Estimation and Linear-Eddy Model formulated PDF and SDR models." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/60295.
Повний текст джерелаАнотація:
Computational fluid dynamics (CFD) is indispensable in the development of complex engines due to its low cost and time requirement compared to experiments. Nevertheless, because of the strong coupling between turbulence and chemistry in premixed flames, the prediction of chemical reaction source terms continues to be a modelling challenge. This work focuses on the improvement of turbulent premixed combustion simulation strategies requiring the use of presumed probability density function (PDF) models. The study begins with the development of a new PDF model that includes the effect of turbulence, achieved by the implementation of the Linear-Eddy Model (LEM). Comparison with experimental burners reveals that the LEM PDF can capture the general PDF shapes for methane-air combustion under atmospheric conditions with greater accuracy than other presumed PDF models. The LEM is additionally used to formulate a new, pseudo-turbulent scalar dissipation rate (SDR) model. Conditional Source-term Estimation (CSE) is implemented in the Large Eddy Simulation (LES) of the Gülder burner as the closure model for the chemistry-turbulence interactions. To accommodate the increasingly parallel computational environments in clusters, the CSE combustion module has been parallelised and optimised. The CSE ensembles can now dynamically adapt to the changing flame distributions by shifting their spatial boundaries and are no longer confined to pre-allocated regions in the simulation domain. Further, the inversion calculation is now computed in parallel using a modified version of an established iterative solver, the Least-Square QR-factorisation (LSQR). The revised version of CSE demonstrates a significant reduction in computational requirement — a reduction of approximately 50% — while producing similar solutions as previous implementations. The LEM formulated PDF and SDR models are subsequently implemented in conjunction with the optimised version of CSE for the LES of a premixed methane-air flame operating in the thin reaction zone. Comparison with experimental measurements of temperature reveals that the LES results are very comparable in terms of the flame height and distribution. This outcome is encouraging as it appears that this work represents a significant step towards the correct direction in developing a complete combustion simulation strategy that can accurately predict flame characteristics in the absence of ad hoc parameters.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Bergmann, Adriana Belmonte. "Um estudo sobre os efeitos decorrentes da inclusão de programas de vacinação no modelo SIR." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/10272.
Повний текст джерелаАнотація:
Um dos propósitos da modelagem de epidemias é estabelecer uma base racional para tomar decisões, tais como estratégias de vacinação para controlar a expansão de uma doença, isto é, para prevenir a ocorrência de uma epidemia. Assim, o estudo de vacinaçõesé um ramo importante da epidemiologia de doenças infecciosas. O objetivo deste trabalho é apresentar alguns conceitos que refletem quantidades relevantes envolvidas nas discussões sobre cobertura de vacina. Con- siderações do número reprodutivo básico e da máxima cobertura vacinal alcançável em um programa são aspectos de grande interesse em estratégia de saúde pública. A partir da versão básica de um modelo epidêmico determinístico com- partimental SIR (suscetível ! infectivo ! removido), e depois de esclarecer a dife- rença entre os termos \imunizado" e \vacinado", define-se a eficácia da vacina como a redução na porcentagem de incidência nos indivíduos vacinados quando comparada com indivíduos não vacinados. Porém, não são levados em conta efeitos indiretos da vacinação, tais como a reduçaõ na exposição causada pelo decréscimo na incidência em pessoas vacinadas próximas aos indivíduos sob observação; em outras palavras, a vacina confere proteção total contra a infecção (efeito esterilizante) para parte dos sujeitos vacinados, mas não confere nenhuma proteção para o restante. A seguir, esta suposição não realística, de que a vacinação não produz resultado algum em alguns indivíduos, pode ser corrigida, incluindo-se novos parâmetros, relacionados a três efeitos indiretos da vacinação, a saber, redução da suscetibilidade, da contagiosidade, bem como da duração da infecção. Para cada modelo, investigamos a existência e a estabilidade local dos estados de equilíbrio e construímos diagramas de bifurcação.One of the purposes of modelling epidemics is to provide a rational basis for decision-making, such as vaccination strategies, in order to control the spread of a disease, that is, to prevent an epidemic occurring. So, the study of vaccinations is an important branch of infectious disease epidemiology. The aim of this work is to point out some concepts which re°ect relevant quantities involved in discussions about vaccine coverage. Thus, considerations of the basic reproductive number, and maximum vaccine coverage achievable in a program are very important real aspects of public health strategy. Starting from the basic version of the SIR (susceptible ! infective ! removed) deterministic compartmental epidemic model, and after clarifying the dif- ference between the terms 'immunized' and 'vaccinated', vaccine e±cacy is de¯ned as the percentage reduction in incidence in vaccinated compared to unvaccinated individuals. However, it does not take into account the indirect e®ects of vacci- nation, like the reduction in exposure caused by decreasing incidence in vaccinated people close to the study subjects; in other words, the vaccine gives total protection against infection (sterilizing e®ect) for a proportion of the vaccinated subjects but none for the rest.Then, this unrealistic assumption that some individuals get no e®ect at all from vaccination can be corrected, by including new parameters related to three indirect e®ects of vaccination, namely, decreased susceptibility, decreased contagiousness and shortened infection duration. For each model, the existence and the local stability of the equilibrium states are investigated and bifurcation diagrams are constructed.
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SERAFIM, Kamila Nayana Carvalho. "Transformando modelos Scade em especificações SCR." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/20342.
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A construção de um software para domínios particulares tem de atender normas específicasque impõem o atendimento a fatores como rastreabilidade de requisitos e certificação. Por exemplo, a indústria aeronáutica deve atender à norma DO-178B que estabelece restrições para uso de software de aeronaves, que são considerados sistemas críticos. Para um sistema estar de acordo com essa certificação é necessário ter requisitos formais e código certificado; nesta direção, Andrade (ANDRADE, 2013) usou a notação SCR (Software Cost Reduction) para definição de requisitos e a ferramenta SCADE para modelagem de sistemas críticos, com desenvolvimento de um tradutor de SCR para artefatos xscade. A prática de desenvolvimento de sistema, porém, não está restrita à transição entre requisitos e artefatos de projeto. Modificações realizadas nestes últimos devem também ser refletidas nos requisitos. Neste trabalho desenvolvemos um tradutor de artefatos de modelagem da ferramenta SCADE para SCR. Desta forma podemos gerar especificação de requisitos a partir do código (Engenharia Reversa) e complementamos o trabalho anterior desenvolvido por Andrade (ANDRADE, 2013). Para o desenvolvimento do tradutor, utilizamos a plataforma Spoofax por meio da qual descrevemos a sintaxe do esquema XML utilizado em SCADE e também as regras de tradução tendo como alvo SCR. A validação da tradução teve como ponto de partida o resultado do uso do tradutor desenvolvido por Andrade (ANDRADE, 2013), tendo de gerar como saída a mesma entrada do tradutor desenvolvido por Andrade (ANDRADE, 2013). Além disso, desenvolvemos exemplos para demonstrar que a modificação estrutural, com preservação de semântica, em projetos SCADE, é verificável por meio do uso de testes gerados por meio da ferramenta TTM-TVEC
Building a software for particular domains must attend specific standards that impose attendance to factors such as traceability requirements and the certification issue. For example, the airline industry should meet the DO-178B standard that establishes restrictions on the use of aircraft software, which is considered a critical system. For a system to be in accordance with this certification, one must have formal requirements and certified code. In this direction, Andrade (ANDRADE, 2013) used SCR (Software Cost Reduction) for requirements definition and SCADE for modeling critical systems with development of an artifacts a translator from SCR. However the practice of developing is not restricted to the transition from requirements to design artifacts. Changes made on design should be reflected in the requirements. In this work we developed a translator from SCADE to SCR. In this way we can generate requirements specification from the code (reverse engineering) and complement the previous Andrade (ANDRADE, 2013) thesis. For the translator development, we use the Spoofax platform through which we describe the XML schema syntax used in SCADE and also the translation rules having SCR as the target language. The translation validation had as its starting point the result of the translator developed by Andrade (ANDRADE, 2013), where the output is the same input developed by Andrade(ANDRADE, 2013). Furthermore, examples developed to demonstrate that the structural modification that preserves semantics in SCADE, is verifiable through the use of tests generated by the TTM-TVEC tool.
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Bossér, Janicke. "IKT i skolan : Hur några pedagoger och barn ser på IKT i skolan utifrån Arne Tragetons modell Skriva sig till läsning." Thesis, Södertörns högskola, Lärarutbildningen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-8881.
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In this essay, I have examined what has been studied and presented in the theory of ICT in schools. I have based my theory on Arne Trageton’s book Att skriva sig till läsning – IKT i förskoleklass och skola (2005) and theories on children’s reading and writing development. The purpose of this study is to determine how teachers and children experience teaching with Trageton’s ICT-based model Att skriva sig till läsning and whether the model is beneficial for children's first reading and writing. Through qualitative interviews with two pedagogues from the same school and some children from first grade, I have received answers to my two questions: How do pedagogues and children experience ICT-based teaching in the context of children's first reading and writing? How do pedagogues experience the reading and writing development in first- and second-language students when using ICT-based teaching? The results showed that both pedagogues and children were positive about the model in which the computer was used as a writing tool in learning to read and write. The teachers felt that the model was suitable for all children according to their conditions. The children saw the writing as very enjoyable. For the ICT-based teaching to work properly, the technology has great significance. The usage of computers is not a problem for neither the pedagogues nor the children. Access to computers is perceived as the reason why there are only two scheduled ICT-based lessons a week
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Pereira, da Silva Hélio Doyle. "Aplicación de modelos bayesianos para estimar la prevalencia de enfermedad y la sensibilidad y especificidad de tests de diagnóstico clínico sin gold standard." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/523505.
Повний текст джерелаАнотація:
Dos objetivos claves de la investigación diagnóstica son estimar con exactitud y precisión la prevalencia de la enfermedad y la sensibilidad y especificidad de tests diagnósticos. Se han desarrollado modelos de clases latentes que tienen en cuenta la correlación entre las medidas de los individuos determinadas con diferentes tests con el fin de diagnosticar enfermedades para las cuales no están disponibles tests gold standard. En algunos estudios clínicos, se hacen varias medidas del mismo individuo con el mismo test en las mismas condiciones y, por tanto, las mediciones replicadas para cada individuo no son independientes. En esta tesis se propone una extensión Bayesiana del modelo de clases latentes de efectos aleatorios de Gauss para ajustar a los datos de tests con resultados binarios y con medidas replicadas por individuo. Se describe una aplicación que utiliza los datos recogidos de personas infectadas por parásitos intestinales Hookworm llevada a cabo en el municipio de Presidente Figueiredo, Estado de Amazonas en Brasil. Además, a través de un estudio de simulación se comparó el desempeño del modelo propuesto con los modelos actuales (el modelo de efectos aleatorios individuo y modelos de dependencia e independencia condicional). Como era de esperar, el modelo propuesto presenta una mayor exactitud y precisión en las estimaciones de prevalencia, sensibilidad y especificidad.
Para un control adecuado de las enfermedades la Organización Mundial de la Salud ha propuesto el diagnóstico y tratamiento de la infección tuberculosa latente (LTBI) en grupos de riesgo de desarrollar la enfermedad, como los niños. No existe un test gold standard para el diagnóstico de la infección latente. Los modelos estadísticos basados en la estimación de clases latentes permiten la evaluación de la prevalencia de la infección y la validez de los tests utilizados en ausencia de un gold standard. Se realizó un estudio transversal con niños de hasta 6 años de edad que habían sido vacunados con la BCG en Manaus, Amazonas-Brasil. El objetivo de dicho estudio fue estimar la prevalencia de la infección latente en los niños pequeños en contacto con un caso indice de tuberculosis en el hogar (TB-HCC) y determinar la validez y la seguridad del test cutáneo de tuberculina (TST) y QuantiFERON-TB Gold-in-tube (QFT), utilizando modelos de clases latentes. Para las estimaciones, en una primera fase se consideró la correlación entre los dos tests, y en la segunda fase se consideró la prevalencia en función de la intensidad y del tiempo de exposición. El cincuenta por ciento de los niños con TB-HCC tenía LTBI, con la prevalencia en función del tiempo y la intensidad de la exposición al caso índice. La sensibilidad y la especificidad de TST fueron del 73 % [intervalo de confianza del 95 % (IC): 53-91] y el 97 % (IC del 95 %: 89-100), respectivamente, frente al 53 % (IC del 95 %: 41-66) y el 81 % (IC del 95 %: 71-90) para QFT. El valor predictivo positivo de TST en niños con TB-HCC fue del 91 % (IC del 95 %: 61-99), y para QFT fue del 74 % (IC del 95 %: 47-95). Este es uno de los primeros estudios que usa modelos de clases latentes para estimar la prevalencia de la infección por M. tuberculosis en niños y los parámetros de sus principales tests diagnósticos. Los resultados sugieren que los niños en contacto con un caso índice tienen un alto riesgo de infección. La validez y los valores predictivos no mostraron diferencias significativas según el test aplicado. El uso combinado de los dos tests en nuestro estudio mostró una sutil mejoría en el diagnóstico de la LTBI.Two key aims of diagnostic research are to accurately and precisely estimate disease prevalence and test sensitivity and specificity. Latent class models have been proposed that consider the correlation between subject measures determined by different tests in order to diagnose diseases for which gold standard tests are not available. In some clinical studies, several measures of the same subject are made with the same test under the same conditions (replicated measurements) and thus, replicated measurements for each subject are not independent. In the present study, we propose an extension of the Bayesian latent class Gaussian random effects model to fit the data with binary outcomes for tests with replicated subject measures. We describe an application using data collected on hookworm infection carried out in the municipality of Presidente Figueiredo, Amazonas State, Brazil. In addition, the performance of the proposed model was compared with that of current models (the subject random effects model and the conditional (in)dependent model) through a simulation study. As expected, the proposed model presented better accuracy and precision in the estimations of prevalence, sensitivity and specificity. For adequate disease control the World Health Organization has proposed the diagnosis and treatment of latent tuberculous infection (LTBI) in groups of risk of developing the disease such as children. There is no gold standard (GS) test for the diagnosis of LTBI. Statistical models based on the estimation of latent class allow evaluation of the prevalence of infection and the accuracy of the tests used in the absence of a GS. We conducted a cross-sectional study with children up to 6 years of age who had been vaccinated with the BCG in Manaus, Amazonas- Brazil. The objective of this study was to estimate the prevalence of LTBI in young children in contact with a household case of tuberculosis (TB-HCC) and determine the accuracy and precision of the Tuberculin Skin Test (TST) and QuantiFERON-TB Gold in-tube (QFT) using the latent class model. Fifty percent of the children with TB-HCC had LTBI, with the pre- valence depending on the intensity and length of exposure to the index case. The sensitivity and specificity of TST were 73 % [95 % confidence interval (CI): 53-91] and 97 % (95 % CI: 89-100), respectively, versus 53 % (95 % CI: 41-66) and 81 % (95 % CI: 71-90) for QFT. The positive predictive value of TST in children with TB-HCC was 91 % (95 % CI: 61-99), and for QFT was 74 % (95 % CI: 47-95). This is one of the first studies to estimate the prevalence of M. tuberculosis infection in children and the parameters of its main diagnostic tests by latent class model. The results suggest that children in contact with an index case have a high risk of infection. The accuracy and the predictive values did not show significant differences according to the test applied. Combined use of the two tests in our study showed scarce improvement in the diagnosis of LTBI.
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Rodrigues, Michele de Oliveira. "SER DOCENTE NA GESTÃO E SER GESTOR NA DOCÊNCIA: UM OLHAR SOBRE A INICIAÇÃO À CARREIRA NO CONTEXTO UNIVERSITÁRIO." Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/7241.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThis study is linked to the Program of Graduate Studies in Education (PPGE), research Line 1 - Formation, Knowledges and Professional Development. It had as its central theme the teaching and management at the beginning of the university career. The general objective of the research was to investigate the management of references that influence the beginner teachers to act as managers coordinators in graduation courses of the Federal University of Santa Maria (UFSM), as regards to the entry into the career and the assumption to management roles at the beginning of the teaching career. Specifically, we worked the following objectives: a) understand the configuration of the management dynamics leds by the beginners managers coordinators in undergraduate courses; b) recognize the confrontations of beginning teachers on assuming management positions in undergraduate courses; c) recognizing learning processes produced by beginning teachers on assuming management positions in undergraduate courses. The methodology involved a qualitative research of narrative bias (BAUER; GASKELL, ALLUM, 2004; BOLIVAR; Sunday; Fernández, 2001; CONNELLY; Clandinin, 1995; HUBERMAN, 1998; MC EWAN, 1998) and the data analysis was given from the discursive textual analysis (MORAES, 2003; MORAES; Galiazzi, 2007). The theoretical-conceptual definition was built from the concepts: complexity of teaching, formation of the trainer and teaching and teacher learning moviments, early teaching career , management models, ambience and teaching resilience.
O presente estudo está vinculado ao Programa de Pós-Graduação em Educação (PPGE), Linha de pesquisa 1 - Formação, Saberes e Desenvolvimento Profissional. Teve como temática central a docência e a gestão no início da carreira universitária. O objetivo geral da pesquisa foi investigar as referências de gestão que influenciam os docentes iniciantes ao atuarem como coordenadores gestores nos cursos de licenciatura da Universidade Federal de Santa Maria (UFSM), no que se refere, à entrada na carreira e a assunção aos cargos de gestão no início da carreira docente. Especificamente, trabalhamos os seguintes objetivos: a) compreender a configuração das dinâmicas de gestão lideradas pelos coordenadores gestores iniciantes nos cursos de licenciatura; b) reconhecer os enfrentamentos dos professores iniciantes ao assumirem cargos de gestão nas licenciaturas; c) reconhecer os processos de aprendizagem produzidos pelos professores iniciantes ao assumirem cargos de gestão nas licenciaturas. O processo metodológico envolveu uma pesquisa qualitativa de viés narrativo (BAUER; GASKELL, ALLUM, 2004; BOLÍVAR; DOMINGO; FERNÁNDEZ, 2001; CONNELLY; CLANDININ, 1995; HUBERMAN, 1998; MC EWAN, 1998) e a análise dos dados deu-se a partir da análise textual discursiva (MORAES, 2003; MORAES; GALIAZZI, 2007). A definição teórico-conceitual foi construída a partir dos conceitos: complexidade da docência, a formação do formador e movimentos da docência e da aprendizagem docente, início da carreira docente, modelos de gestão, ambiência e resiliência docente.
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Zhuang, Lili. "Bayesian Dynamical Modeling of Count Data." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1315949027.
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Duggan, Paul D. "Incorporating neighbohood [sic] social patterns into neighborhood planning models." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1193079805/.
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Gütlein, Martin [Verfasser]. "Visualization and Validation of (Q)SAR Models / Martin Gütlein." Mainz : Universitätsbibliothek Mainz, 2015. http://d-nb.info/107443482X/34.
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Barratt, Nicholas Roy. "The simulation of SAR imagery using discretised scattering models." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283117.
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Ashraf, Hina. "Investigation of the Symmetries of the Phonons in 4H and 6H-SiC by Infrared Absorption and Raman Spectroscopy." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6079.
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The goal of the project work has been to study the symmetry of the phonons in 4H and 6H-SiC for different measuring geometries by using two experimental techniques, Raman and infrared absorption (IR) spectroscopy, and a theoretical model. The Raman spectra were measured in different scattering configurations in order to obtain experimental data for detailed investigation of the phonon symmetries.
The gross features of the spectra obtained in different geometries can be explained using general group-theoretical arguments. Using a lattice-dynamics model, we have also calculated the angular dependence of the phonon energies near the centre of the Brillouin zone, as well as the phonon displacements in some high-symmetry directions. The theoretical results are used to interpret the Raman lines in different configurations, and it was possible to estimate that if ionicity of the bonding of 12% is taken in the theoretical model for 4H-SiC, the splitting of the polar TO mode and the shift of the polar LO mode observed in our spectra are well reproduced theoretically. It was also observed that these polar modes have to be classified as longitudinal and transversal with respect to the direction of phonon wave vector, while the rest of the modes remain longitudinal or transversal with respect to the c-axis of the crystal. The Raman lines in the case of 4H SiC have been tentatively labelled with the irreducible representations of the point group of the crystal (C6v).
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Nusbacher, Aryeh J. S. "The triple thread : supply of victuals to the army under Sir Thomas Fairfax 1645-1646." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391170.
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SABETI, Mehran. "Modelo Epidêmico Discreto SIR com estrutura etária e aplicação de vacinação em pulsos e constante." Universidade Federal de Pernambuco, 2011. https://repositorio.ufpe.br/handle/123456789/1321.
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Previous issue date: 2011Conselho Nacional de Desenvolvimento Científico e Tecnológico
Nesta tese estudaremos a dinâmica de vacinação do modelo epidêmico discreto SIR em que são consideradas indivíduos de um universo em três categorias possíveis; suscetível, infectado e recuperado em relação a algum estado prêdefinido. Um aspecto importante do trabalho é o ponto de vista distinto para estudar o modelo epidemiológico SIR, que concorda com os modelos contínuos e é mais prático para aplicar os dados reais. Este trabalho está dividido em duas partes. Na primeira parte, foi desenvolvido um modelo matemático SIR baseado nos dados biológicos discretos. O modelo inclui a estrutura etária da população humana através da dinâmica da matriz de Leslie. Na segunda parte, aplicamos dois tipos de estratégias de vacinação, vacinação constante e vacinação em pulso, e comparamos os resultados obtidos nestas estratégias. Mostramos que, sob um regime previsto a vacinação em pulsos o sistema converge para uma solução estável, com número de indivíduos infecciosos sendo igual a zero. Mostramos também que a vacinação em pulsos implicará na eliminação de epidemias se certas condições a respeito da magnitude da taxa de vacinação e da duração dos pulsos forem observadas. Os resultados teóricos são confirmados por simulações numéricas. A introdução básica de variações sazonais no modelo SIR conduz à dinâmica periódica e caótica da epidemia. É mostrado que, sob a variação sazonal, apesar da complexa dinâmica do sistema, leva a vacinação para a erradicação das epidemias. Deduzimos as condições para a erradicação da epidemia sob diversas restrições e estudamos a eficácia e o custo do vacinação em pulso, também comparamos as políticas de vacinação constantes e mistas