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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

Estimação de funções do redshift de galáxias com base em dados fotométricos / Galaxies redshift function estimation using photometric data

Gretta Rossi Ferreira 18 September 2017 (has links)
Em uma quantidade substancial de problemas de astronomia, tem-se interesse na estimação do valor assumido, para diversas funções g, de alguma quantidade desconhecida z ∈ ℜ com base em covariáveis x ∈ ℜd. Isto é feito utilizando-se uma amostra (X1, Z1), ... (Xn, Zn). As duas abordagens usualmente utilizadas para resolver este problema consistem em (1) estimar a regressão de Z em x, e plugar esta na função g ou (2)estimar a densidade condicional f (z Ι x) e plugá-la em ∫ g(z) f (z Ι x)dz. Infelizmente, poucos estudos apresentam comparações quantitativas destas duas abordagens. Além disso, poucos métodos de estimação de densidade condicional tiveram seus desempenhos comparados nestes problemas. Em vista disso, o objetivo deste trabalho é apresentar diversas comparações de técnicas de estimação de funções de uma quantidade desconhecida. Em particular, damos destaque para métodos não paramétricos. Além dos estimadores (1) e (2), propomos também uma nova abordagem que consistem em estimar diretamente a função de regressão de g(Z) em x. Essas abordagens foram testadas em diferentes funções nos conjuntos de dados DEEP2 e Sheldon 2012. Para quase todas as funções testadas, o estimador (1) obteve os piores resultados, exceto quando utilizamos florestas aleatórias. Em diversos casos, a nova abordagem proposta apresentou melhores resultados, assim como o estimador (2). Em particular, verificamos que métodos via florestas aleatórias, em geral, levaram a bons resultados. / In a substantial a mount of astronomy problems, we are interested in estimating values assumed of some unknown quantity z ∈ ℜ, for many function g, based on covariates x ∈ ℜd. This is made using a sample (X1, Z1), ..., (Xn, Zn). Two approaches that are usually used to solve this problem consist in (1) estimating a regression function of Z in x and plugging it into the g or (2) estimating a conditional density f (z Ι x) and plugging it into ∫ g(z) f (z Ι x)dz. Unfortunately, few studies exhibit quantitative comparisons between these two approaches.Besides that, few conditional density estimation methods had their performance compared in these problems.In view of this, the objective of this work is to show several comparisons of techniques used to estimate functions of unknown quantity. In particular we highlight nonparametric methods. In addition to estimators (1) and (2), we also propose a new ap proach that consists in directly estimating the regression function from g(Z) on x. These approaches were tested in different functions in the DEEP 2 and Sheldon 2012 datasets. For almost all the functions tested, the estimator (1) obtained the worst results, except when we use the random forests methods. In several cases, the proposed new approach presented better results, as well as the estimator (2) .In particular, we verified that random forests methods generally present to good results.
322

Discriminação condicional com apresentação seriada de estímulos e teste de equivalência em ratos / Conditional discrimination with serial presentation of stimuli and tests for equivalence in rats

Müller Wagenheimer Lima 03 October 2012 (has links)
No procedimento de discriminação condicional de origem skinneriana, geralmente, usa-se o procedimento de matching-to-sample (MTS). Esse procedimento também é utilizado para se estudar a equivalência de estímulos. Sidman e Tailby (1982) estabeleceram três testes para verificar se estímulos usados em tarefas de discriminação condicional podem ser considerados equivalentes entre si: reflexividade, simetria e transitividade. No procedimento de discriminação condicional de origem pavloviana, os estímulos podem ser apresentados de duas formas: simultânea e seriada. Na apresentação simultânea, os estímulos são apresentados juntos ou sucessivamente, sem intervalo entre suas apresentações (XA). Na apresentação seriada há um intervalo entre as apresentações dos estímulos (XA). Dependendo da forma de apresentação dos estímulos, diferentes associações entre os estímulos e o estímulo incondicionado (US) são formadas. Quando a apresentação é simultânea, forma-se uma associação entre o estímulo X e o US. Quando a apresentação é seriada, forma-se uma associação entre o estímulo A e o US e o estímulo X estabelece a ocasião para a ocorrência da relação entre A e US ocorre (Ross & Holland, 1981). Na discriminação condicional de origem pavloviana, a liberação do US não depende do comportamento do rato. Entretanto, o procedimento também pode ser usado com comportamento operante. No presente trabalho, buscou-se estudar o efeito da apresentação seriada dos estímulos sobre o desempenho de ratos durante os testes de equivalência de estímulos em um procedimento de discriminação condicional. Foram utilizados 32 ratos machos Wistar. O experimento envolveu diversas fases: (a) treino ao bebedouro, (b) modelagem do comportamento de pressão à barra, (c) CRF, (d) discriminação simples, (e) discriminação condicional, (f) testes de transferência e os de equivalência de estímulos (reflexividade, simetria e transitividade). Os ratos foram divididos em 2 grupos: o Simultâneo e o Seriado. No grupo Simultâneo, os estímulos foram apresentados sucessivamente, não havendo intervalo de tempo entre suas apresentações, enquanto que no grupo Seriado, houve um intervalo de 5 segundos entre as apresentações dos estímulos. Cada um desses grupos foram subdivididos em 2 grupos: grupo Tom e grupo Luz. No primeiro grupo, o estímulo característica usado foi um Tom, enquanto que no segundo grupo o estímulo foi uma Luz. Os resultados mostraram que os ratos aprenderam a tarefa de discriminação condicional. No teste de transferência observou-se que houve transferência em praticamente todos os 4 grupos. Durante o teste de equivalência, foi observadas a emergência de algumas relações. Na discussão, os dados foram discutidos a partir das literaturas de discriminação condicional de origem skinneriana e de origem pavloviana. / In a Skinnerian conditional discrimination procedure generally the procedure of matching-to-sample (MTS) is used. This procedure is also used to study the stimulus equivalence. Sidman and Tailby (1982) established three tests to verify whether stimuli used in conditional discrimination tasks can be considered equivalent to each other: reflexivity, symmetry and transitivity. In a Pavlovian conditional discrimination procedure, the compounds of stimuli may be in two forms: simultaneous and serial. In the simultaneous compounds, the stimuli are presented together or successively, without an interval between their presentations (XA). In the serial compounds there is an interval between stimuli presentations (X A). Depending on the form of presentation of the compounds of stimuli, different associations between stimuli and the unconditioned stimulus (US) are formed. In a simultaneous compound of stimuli an association between stimulus X and the US is formed. In a serial compound of stimuli an association between the stimulus A and the US is formed and the stimulus X sets the occasion for the occurrence of the association between stimulus A and the US (Ross & Holland, 1981). In Pavlovian conditional discrimination, the US presentation does not depend on the behavior of the rat. However, the procedure can also be used with operant behavior. In this study, we sought to study the effect of serial presentation of stimuli on the performance of rats during tests of equivalence of stimuli in a conditional discrimination procedure. We used 32 male Wistar rats. The rats were divided into two groups: Simultaneous Compounds and Serial Compounds. In the Simultaneous Compounds Group, stimuli were presented successively with no interval between their presentations. In the Serial Compounds Group, there was an interval of 5 seconds between the presentations of stimuli. Each of these groups was subdivided into two groups: Tone and Light. In the Tone Group, the feature stimulus used was a tone, and in the Light Group the feature stimulus was a light. The results of the experiment showed that the rats learned the task of conditional discrimination. In the transfer test was observed substantial transfer in almost all four groups. During the equivalence test were observed emergence of certain relationships. In the discussion, the data were discussed using the literature from Skinnerian conditional discrimination and from Pavlovian conditional discrimination.
323

Equivalência de estímulos em crianças portadoras da síndrome de apert / Stimulus equivalence in children with Apert Syndrome

Daniela de Almeida Casteleti 03 May 2011 (has links)
O presente estudo investigou comportamentos simbólicos nos portadores de Síndrome de Apert por meio do paradigma da equivalência de estímulos, uma vez que este pode fornecer subsídios para a compreensão do comportamento humano complexo, tais como o comportamento simbólico e a linguagem. Foram propostos três experimentos cujos participantes, com idades entre 16 e 21 anos, foram submetidos aos Experimentos 1 e 2 (P1, P2 e P3) e submetidos ao Experimento 3 (P4 e P5). No Experimento 1, o objetivo foi verificar a formação de classes de estímulos equivalentes após o treino de relações condicionais, por meio de uma tarefa de matching to sample (MTS) com atraso de 0 s e três estímulos de comparação. Após o participante atingir um percentual de acerto de 94% no bloco, foram conduzidos testes de equivalência (CA), simetria (BA e CB) e transitividade (AC). De maneira geral, houve falha nos testes, com relativa preservação do teste de simetria. No Experimento 2, os participantes foram expostos à tarefa de MTS com atraso de 0 s e três estímulos de comparação, mas estes e o estímulo modelo apresentavam-se inicialmente cobertos, tornando-se visíveis somente após a emissão de respostas de observação (ROs). Foram introduzidas ROs na tarefa de MTS, com o objetivo de identificar que tipos de controle (seleção ou rejeição) poderiam estar em operação na formação de classes de estímulos equivalentes. Nos testes, o participante P3 formou classes de equivalência, contudo, os participantes P1 e P2 continuaram a apresentar falha na formação de equivalência, com preservação do teste de simetria. No Experimento 3, foram apresentadas variações metodológicas com o objetivo de favorecer o estabelecimento de um ou de outro tipo de controle (seleção ou rejeição), durante o treino das relações condicionais e verificar os efeitos destas variações no desempenho obtido nos testes. O participante P4 foi submetido primeiramente à situação na qual a terceira RO produzia o estímulo correto em 80% das tentativas (80%/3ª S+). Posteriormente 9 à realização das tarefas sob esta condição, foi submetido à situação na qual a primeira RO produzia o estímulo correto em 80% das tentativas (80%/1ª S+). O participante P5 foi exposto à ordem inversa: primeiramente à situação 80%/1ª S+ e posteriormente à situação 80%/3ª S+. Nos testes, em ambas as situações, o participante P4 foi capaz de aprender as relações de equivalência propostas pelo experimentador. Diferentemente, o responder do participante P5 não se apresentou sob controle discriminativo das contingências programadas pelo experimentador. De um modo geral, os resultados obtidos pelo presente estudo acrescidos das análises do teste PEABODY, sugerem que as dificuldades para a formação de classes de equivalência em participantes com baixo funcionamento lingüístico podem decorrer, em grande parte, de preparação e adaptação insuficiente de procedimentos para esse tipo de população / The present study investigated the symbolic behaviors of patients with Apert Syndrome through the paradigm of stimulus equivalence, since it may provide a basis for understanding complex human behavior, such as symbolic behavior and language. It had been proposed three experiments which participants, aged between 16 and 21 years, were submitted to Experiments 1 and 2 (P1, P2 and P3) and to Experiment 3 (P4 e P5). In Experiment 1, the objective was to assess the formation of classes of equivalent stimuli after training of conditional relations, through a task of matching to sample (MTS) and delay of 0s and three comparison stimuli. After the participant reaches a 94% criterion for accuracy in the block, tests were conducted for equivalence (CA), symmetry (BA and CB) and transitivity (AC). In general, the participants failed the tests, with relative preservation of the symmetry test. In Experiment 2, the participants were exposed to the task of MTS with delay of 0s and three comparison stimuli, but these and the sample stimulus were initially covered, becoming visible only after the observation responses (OR´s) issuance. ORs were introduced in the MTS task, with the objective to assess what kind of different controls (selection and rejection) could be involved in the formation of classes of equivalent stimuli. In tests, participant P3 showed the formation of classes of equivalent stimuli; however, participants P1 and P2 had failed to form equivalence, preserving the symmetry test. In Experiment 3 were presented methodological variations with the objective of encouraging the establishment of one or another type of control (selection or rejection) during the training of conditional relations and verify the effects of these variations in performance obtained in tests. Participant P4 was, at first, subjected to the situation which the third OR produced the correct stimulus in 80% of attempts (80% / 3rd S +). After the tasks under this condition were performed, P4 underwent a situation which the first OR produced the correct stimulus in 80% of attempts (80% / 1st S +). The participant P5 was exposed to the reverse order: first of all to the situation 80% / 1st S + and subsequently to the situation 80% / 3rd S +. In the tests, in both situations, the participant P4 was able to learn the equivalence 11 relations proposed by the experimenter. In contrast, the response of the participant P5 was not under discriminative control of the contingencies programmed by the experimenter. In general, the results obtained by this study plus the analysis of the PEABODY data suggests that difficulties in the formation of equivalence classes in participants with low language functioning may be due, in large part from inadequate preparation and adjustment procedures for this type of population
324

Transferência condicionada de renda e segurança alimentar em espaços rurais: uma análise do Programa JUNTOS na comunidade indígena de Pilpichaca no Peru / Conditional cash transfer and food security in rural areas: Analyze of the Program JUNTOS in Pilpichaca indigenous community in Peru

Violeta Magdalena Rojas Huayta 22 February 2011 (has links)
As sociedades mundiais passam por mudanças substanciais que repercutem nas áreas da segurança alimentar e das políticas públicas sociais. Apesar de terem ocorrido significativas conquistas econômicas e sociais nos últimos anos, no Peru ainda existe dificuldade para oferecer segurança alimentar a toda sua população e isto se reflete na alta prevalência de subnutrição infantil concentrada principalmente nos espaços rurais, onde até o primeiro semestre de 2010, 30,9% das crianças são subnutridas. Esta situação representa uma ameaça para a sustentabilidade do desenvolvimento do Peru, devido aos efeitos irreversíveis da subnutrição na capacidade intelectual e física do indivíduo. Sendo a pobreza uma das principais causas da subnutrição, os programas de transferência condicionada de renda têm um grande potencial em favorecer a segurança alimentar dos beneficiados. Neste contexto o presente estudo tem como objetivo mostrar os reflexos na segurança alimentar dos beneficiados do programa de transferência condicionada de renda JUNTOS, na comunidade indígena de Pilpichaca, uma das comunidades mais pobres e com maior prevalência de crianças subnutridas do Peru. Foi realizado um estudo descritivo e quantitativo em uma amostra de 90 famílias. A escolha das famílias beneficiadas foi feita aleatoriamente em uma relação de todas as famílias beneficiadas com crianças menores de cinco anos. O levantamento dos dados foi feito através de questionário fechado apresentado as mães. Pretendia-se conhecer: a forma de acesso aos alimentos, à água e esgoto, acesso aos programas públicos de suplementação e complementação alimentar, uso da transferência de renda, mudança no consumo de alimentos, o estado nutricional nas crianças menores de cinco anos, a relação entre as variáveis: estado nutricional e o tempo de exposição ao programa JUNTOS; e a avaliação do Programa JUNTOS pelas mães beneficiadas. Os resultados mostram que aumentou o consumo de alimentos de alto valor nutritivo e o gasto com alimentos também é favorecido. Os resultados da regressão linear apontam que há uma relação proporcional entre o estado nutricional e o tempo de exposição ao programa JUNTOS, mas esta não é estatisticamente significativa. A transferência de renda representa 51.2% da renda familiar e as mães avaliaram o programa JUNTOS como uma boa política pública. / In Peru, although significant economic and social achievements have occurred in recent years, there is still a difficulty in providing food to entire population. This is reflected in a high prevalence of child malnutrition, mainly concentrated in rural areas, where, in the first half of 2010, even 30.9% of children is malnourished. This situation represents a threat to sustainable development of Peru, the irreversible effects of malnutrition on physical and intellectual capacity of the individual. With poverty being a major cause of malnutrition, the programs of conditional cash transfer have great potential to promote food security of beneficients. In this context, this study aims to show the effects of food security of the beneficients of the program of conditional cash transfer: JUNTOS, in the indigenous community of Pilpichaca, one of the poorest communities and with the highest percentage of malnourished children in Peru a descriptive and quantitative analysis on a sample of 50 families was made. The choice of beneficiary households was made randomly from a list of all beneficiary families with children under 5 years. The survey was made through different closed questionnaires presented to the mothers. The aim was to know: how to access food, water and sanitation, as well as public programs to food complement and supplementation, use of income transfer, change in food consumption, nutritional status among children under five years, the relationship between variables: nutritional status and exposure time to the program JUNTOS and program JUNTOS evaluation by mothers benefited. The results show that increased intake of foods of high nutritive value, spending on food is in plus, but can not show a significant relationship, between nutritional status and exposure time to the program JUNTOS. The transfer of income represents 51.2% of a total family income. The mothers generally rated JUNTOS as a good public policy.
325

An investigation of the possibility of defining a new conditional access application programming interface for digital television receivers / En undersökning av möjligheten att definiera ett nytt Conditional Access Application Programming Interface för digitaltvmottagare

Anstensen, Jan January 2002 (has links)
Digital television broadcasters use conditional access (CA) systems to protect some of their services from being viewed by people not subscribing for these services. A manufacturer of digital television receivers develops applications to handle the CA systems that the receiver shall support. A problem for the application developer is that a CA application developed for one specific CA system is usually not reusable for other CA systems because of the differences between CA systems. The CA systems are different in both their application programming interfaces (API) as well as the types of functionality that they support. This master thesis presents a study of three APIs from different CA systems. The possibilities of defining a new CA API that supports all the functionality that is provided by existing CA APIs while still being as similar as possible to these existing APIs are investigated. The conclusion from the study is that it is not possible to define this new CA API because the studied CA systems are so different and only small parts of the provided functionality are shared between them.
326

Conditional and Unconditional Transfers : Remittances and the take-up of CCT programs in developing countries

Sundman, Viktor January 2016 (has links)
This study examines the relationship between reception of remittances and CCT participation. Three hypotheses, predicting a negative relationship between remittances and CCTs, are presented. These are tested by logit regressions based on data from national household surveys from four Latin American countries. The study finds some support for a negative correlation between remittances and CCT participation, but lack of data restricts the possibility of drawing firm conclusions from the study.
327

Podmíněné zastavení trestního stíhání / Conditional discontinuance of criminal prosecution

Nacházel, Vojtěch January 2016 (has links)
This diploma thesis focuses on issues connected with conditional discontinuation of criminal prosecution. This concept enables to temporarily suspend criminal prosecution with the provision that if the accused complies with certain set conditions during a certain probation period, the criminal prosecution will be discontinued with final effect. This paper chiefly aims to analyse in detail the conditions required by the Code of Criminal Procedure for the application of conditional discontinuation of criminal prosecution. The paper also presents a brief analysis of the conditions required for other diversions of criminal proceedings permitted under Czech laws. This diploma thesis consists of the introduction, five individual chapters, of which the third and fourth are further divided into subchapters, and the conclusion. The first chapter deals with the concept of restorative justice, which serves as the ideological basis for procedural diversions. An analysis of its individual values, principles and ideas is presented. The first chapter also includes an outline of the programmes under which restorative justice is being developed. The conclusion of this chapter contains the author's thoughts concerning the individual programmes and their implementation in the Czech legislation. The second chapter...
328

Robustní metody v teorii portfolia / Robust methods in portfolio theory

Petrušová, Lucia January 2016 (has links)
01 Abstract: This thesis is concerned with the robust methods in portfolio theory. Different risk measures used in portfolio management are introduced and the corresponding robust portfolio optimization problems are formulated. The analytical solutions of the robust portfolio optimization problem with the lower partial moments (LPM), value-at-risk (VaR) or conditional value-at-risk (CVaR), as a risk measure, are presented. The application of the worst-case conditional value-at-risk (WCVaR) to robust portfolio management is proposed. This thesis considers WCVaR in the situation where only partial information on the underlying probability distribution is available. The minimization of WCVaR under mixture distribution uncertainty, box uncertainty, and ellipsoidal uncertainty are investigated. Several numerical examples based on real market data are presented to illustrate the proposed approaches and advantage of the robust formulation over the corresponding nominal approach.
329

Neparametrické regresní odhady / Nonparametric regression estimators

Měsíček, Martin January 2017 (has links)
This thesis is focused on local polynomial smoothers of the conditional vari- ance function in a heteroscedastic nonparametric regression model. Both mean and variance functions are assumed to be smooth, but neither is assumed to be in a parametric family. The basic idea is to apply a local linear regression to squa- red residuals. This method, as we have shown, has high minimax efficiency and it is fully adaptive to the unknown conditional mean function. However, the local linear estimator may give negative values in finite samples which makes variance estimation impossible. Hence Xu and Phillips proposed a new variance estimator that is asymptotically equivalent to the local linear estimator for interior points but is guaranteed to be non-negative. We also established asymptotic results of both estimators for boundary points and proved better asymptotic behavior of the local linear estimator. That motivated us to propose a modification of the local li- near estimator that guarantees non-negativity. Finally, simulations are conducted to evaluate the finite sample performances of the mentioned estimators.
330

Podmíněné zastavení trestního stíhání / Conditional discontinuance of criminal prosecution

Plávková, Andrea January 2017 (has links)
Conditional discontinuance of criminal prosecution is an institute that was introduced into Czech criminal procedure law more than twenty years ago. Over the years, this alternative way of handling criminal cases has become the most commonly used (in the last four years, the second most commonly used) means of all alternative ways called diversions. This diversion is used by both prosecutors and courts in cases of less serious criminal offenses. The point of conditional discontinuance of criminal prosecution is the decision of the prosecutor or the court not to initiate criminal court proceedings or cease them under certain conditions, the most important of them being the offender reimbursing the injured party for the damages caused by the crime. The goal of the author of this thesis is to briefly write about the history of alternative ways of handling criminal cases and their introduction into Czech criminal law, then to move on to specifically discussing the institute of conditional discontinuance of criminal prosecution, the conditions that must be met for its use, the benefits it brings into Czech criminal law and criminal proceedings and to compare it with other types of diversions, as well as with the use of the same institute in Slovak criminal law under slightly different conditions. The...

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