Doctor of Philosophy / Department of Civil Engineering / Sunanda Dissanayake / Young drivers are over-represented in crashes when compared to other age group drivers. Distracted driving is one of the major causes of traffic crashes by young drivers. The objective of this study was to assess the hazards of distracted driving among teenage (15–20 year old) and young-adult (21–26 year old) drivers in Kansas. This study used five years of crash data from the Kansas Crash and Analysis Reporting System (KCARS) database from 2011 to 2015. A multinomial logit modeling was used to identify the odds that a driver with a certain type of distraction would be involved in one of the three most common crash types: rear-end, angular, and single-vehicle crashes. Furthermore, ordered logistic modeling was used to analyze the crash data to identify the odds of more severe injuries for teenage and young-adult distracted drivers and their passengers involved in crashes. Survey data was used to develop a structural equation model (SEM) to define the relationship among young drivers’ characteristics (e.g., participants’ socioeconomic and demographic status), attitudes, and behaviors associated with distracted driving and cell phone use while driving. Preliminary analysis showed that more than 12% of the total young drivers’ crashes were distraction-affected crashes. According to the multinomial logit model results, most distraction types for teenage and young-adult drivers are related to rear-end or angular collisions. However, when distracted by cell phones at night, teenage drivers had a greater probability of being involved in single-vehicle crashes. In addition, when teenage drivers drove with their peers as front-seat passengers and were distracted in/on vehicle or by other electronic devices, they were more likely to be involved in single-vehicle crashes. Young-adult drivers distracted in/on vehicle or by cell phones under different conditions such as while driving old or sport utility vehicles, on curved roads, or at intersections, they were more likely to be involved in single-vehicle or angular crashes. Whereas, when they were inattentive during the weekend, rear-end collisions were the most likely collision type. According to the results of the ordered logistic model, teenage and young-adult drivers were more likely to be severely injured in cell phone-related crashes. More specifically, female teenage drivers had a greater probability of being severely injured than male teenage drivers when they were distracted by a cell phone, inside the vehicle, or were inattentive. Young-adult drivers that were distracted on road construction work zones by a cell phone or inside the vehicle, they and their passengers had a greater likelihood of sustaining a severe injury. The SEM results revealed that teenage drivers are more prone than young-adult drivers to drive while distracted and are less likely to support the Kansas laws that ban cell phone use while driving. Also, the model results showed that young drivers who have been involved in crashes or near-crashes during the previous year are more likely to drive while distracted. These results indicate that distractions create threats to the lives of young Kansas drivers, their passengers, and other road users.

Orientador: Alexandre Sartoris Neto / Banca: Luciana Togeiro / Banca: Marislei Nishijima / Resumo: A Educação Superior pode ser considerada uma ferramenta que possibilita ao indivíduo, através do investimento em seu Capital humano, ampliação de sua capacidade produtiva, maiores salários, proporcionando menor iniqüidade na distribuição de renda entre os indivíduos. O objetivo deste trabalho é traçar um perfil sócio-econômico do recém formado no ensino superior brasileiro com base em dados do Exame Nacional do Desempenho dos Estudantes (ENADE). Como se sabe, a escolha do curso superior no Brasil tem forte influência de fatores sociais e econômicos. Para estimar probabilidades com que um graduado seja de determinado curso, dado seu perfil, um modelo logit multinomial foi estimado. Conclui-se que quando a expectativa em relação ao curso é de ganhos futuros, homens brancos, negros e mulatos tendem a escolher cursos de exatas e engenharias. Em contrapartida, os cursos de humanas, em sua maioria, são demandados por mulheres brancas, negras e mulatas. Mesmo assim, há mulheres brancas, em certas regiões como Sudeste e Sul, que tem preferência por curso de engenharias e exatas / Abstract: Higher education can be considered a tool that enables an individual, through investment in human capital, expanding his or her production abilities, higher wages, providing less unequal distribution of income among individuals.This work aims to build a profile of the Brazilian college graduated based on data from ENADE (Student Performance National Exam). As fairly known, college career choice in Brazil is strongly affected by social and economic factors. In order to estimate the probability of choosing a career, given the student profile, a multinomial logit model will be estimated. It is possible to conclude that when the expectation is over the course of future earnings, white males, blacks and mulattoes tend choose the exact and engineering courses. In contrast, the humanities courses, mostly, are demanded by white, black and mulatto. Still, there are white women in certain regions such as Southeast and South, which has a preference for engineering courses and exact / Mestre

Made available in DSpace on 2015-03-03T15:22:32Z (GMT). No. of bitstreams: 1 HeleniceLB.pdf: 332420 bytes, checksum: fb2f282668ca77bc36aa9e12c586706d (MD5) Previous issue date: 2009-08-17 / Este trabalho tem como objetivo o estudo do comportamento assint?tico da estat?stica de Pearson (1900), que ? o aparato te?rico do conhecido teste qui-quadrado ou teste x2 como tamb?m ? usualmente denotado. Inicialmente estudamos o comportamento da distribui??o da estat?stica qui-quadrado de Pearson (1900) numa amostra {X1, X2,...,Xn} quando ?n ? ? e pi = pi0 , ?8n. Em seguida detalhamos os argumentos usados em Billingley (1960), os quais demonstram a converg?ncia em distribui??o de uma estat?stica, semelhante a de Pearson, baseada em uma amostra de uma cadeia de Markov, estacion?ria, erg?dica e com espa?o de estados finitos S

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-04T18:04:19Z No. of bitstreams: 1 hermesaugustooliveirarabelo.pdf: 1597707 bytes, checksum: 60df1d97256f77c6b5615469af3f3435 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T16:22:06Z (GMT) No. of bitstreams: 1 hermesaugustooliveirarabelo.pdf: 1597707 bytes, checksum: 60df1d97256f77c6b5615469af3f3435 (MD5) / Made available in DSpace on 2016-07-13T16:22:06Z (GMT). No. of bitstreams: 1 hermesaugustooliveirarabelo.pdf: 1597707 bytes, checksum: 60df1d97256f77c6b5615469af3f3435 (MD5) Previous issue date: 2012-04-27 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / O presente trabalho tem como objetivo verificar os determinantes da estrutura de capital em diferentes estágios de desenvolvimento das empresas sob a visão da Life Cycle Theory de Berger e Udell (1998). Esta teoria ressalta as diferentes fontes de financiamento que são utilizadas pelas empresas em diferentes momentos de sua vida. O banco de dados utilizado no trabalho foi retirado do software Economática, do qual foi possível observar dados dos balanços patrimoniais das empresas de capital aberto listadas na Bovespa entre os anos de 1996 a 2010. Dessa forma, o presente estudo utilizou a metodologia de análise de dados em painel através do Modelo de Regressão Logit Multinomial e do modelo logit Binomial. De modo a considerar a correlação entre as variáveis e reduzir o número delas no modelo, foi utilizada a Análise de Componentes Principais (PCA). Os resultados encontrados na pesquisa sugerem que a mudança na principal fonte de financiamento é influenciada por fatores como liquidez, colateral, risco e idade. Em relação à idade da empresa, há evidências de que, para empresas de mais de 30 anos de abertura de capital, a probabilidade de a empresa alterar sua principal fonte de financiamento é menor quando comparada a empresas mais jovens. No modelo logit multinomial, os resultados encontrados evidenciam um efeito positivo das empresas enquadradas como de médio e grande porte sobre a probabilidade de utilizar empréstimos de curto e longo prazo e financiamento interno quando comparadas com as empresas de pequeno porte. Em relação à idade desde a abertura de capital, os resultados da pesquisa mostram que empresas com mais de 30 anos apresentaram maior probabilidade de escolher financiamento para giro e fundos internos (lucros acumulados) quando comparadas com empresas que abriram capital mais recente e utilizam crédito de fornecedores. Apesar de alguns dos resultados estarem em conformidade com o apregoado por Berger e Udell (1998), a pesquisa evidencia muitos aspectos relacionados à Pecking Order Theory. / This study aims to focus on capital structure determinants in different stages of development in the entrepreneurial environment under Life Cycle Theory of Berger and Udell (1998). This theory emphasizes different funding sources which are used by companies in different cycles of their lives. The data were generated and processed according to the Brazilian Economática software. Balance sheets provided by public corporations and listed at Bovespa Stock Exchange during 1996-2010 were considered for analysis. Panel Data are important points in methodological plan. Indeed, Multinomial Logit and Binomial Logit models were used to investigation. Development process effects by corporations upon their own financing were detailed and looking for adding the correlation among variables and minimizing their effects, the Principal Component Analysis (PCA) was attained for diagnosis. Results suggest changing on the main funding source, influenced by factors such as liquidity, collateral and risk. Regarding firms' age, there is evidence that companies with more than thirty years of initial IPO are less likely to change their main source of funding. According to the multinomial logit model, results suggest that large companies are more likely using short-term loans and internal funding than trade credit that those classified in small businesses. Although some results are consistent to those claimed by Berger and Udell (1998), research provides some aspects related to Pecking Order Theory.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-10-10T14:49:33Z No. of bitstreams: 1 philipescherrermendes.pdf: 346564 bytes, checksum: 67ae50b48a6d6b505287fb67ce1da5a0 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-10-11T15:54:22Z (GMT) No. of bitstreams: 1 philipescherrermendes.pdf: 346564 bytes, checksum: 67ae50b48a6d6b505287fb67ce1da5a0 (MD5) / Made available in DSpace on 2016-10-11T15:54:22Z (GMT). No. of bitstreams: 1 philipescherrermendes.pdf: 346564 bytes, checksum: 67ae50b48a6d6b505287fb67ce1da5a0 (MD5) Previous issue date: 2009-12-15 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A proposta deste trabalho é abordar os fatores que condicionam a mobilidade de trabalhadores através do território. Nesse sentido, são abordados fatores de atração e repulsão pela literatura de Economia do Trabalho a fim de avaliar a extensão territorial da mobilidade do trabalhador, tendo em vista que a literatura de Economia da Tecnologia, e sua vertente regional, enfatiza que a mobilidade de trabalhadores qualificados é importante para transferir conhecimento de natureza tácita entre regiões, com claras repercussões sobre a possibilidade de desenvolvimento regional. Neste diálogo, estabelece-se conceitos teóricos que abordem questões relacionadas aos determinantes econômicos da mobilidade de trabalhadores e questões relacionadas à capacidade que os trabalhadores qualificados possuem de transmitir conhecimento tecnológico ao se moverem, favorecendo o desenvolvimento. Com o uso dos micro-dados da RAIS-Migra (MTE), acompanha-se uma amostra dos trabalhadores, empregados na indústria de transformação, ao longo de oito anos (1995-2002), e apresenta-se a composição do emprego formal no Brasil por setores com diferentes graus de intensidade tecnológica. A partir de modelos de regressão logística multinomial, o trabalho revela que a mobilidade é positivamente relacionada com o salário, com o sexo masculino e com o nível de escolaridade do trabalhador. Por outro lado, há uma relação negativa com o nível de senioridade do trabalhador. Além disso, todos esses resultados diferem significativamente em termos da extensão territorial da mobilidade, o que é possível observar pelo uso da metodologia multinomial. / The purpose of this paper is to study the factors that interfere on the mobility of workers through the space. Factors of attraction and repulsion are studied using the Labor Economics to verify the territorial extension of the mobility of workers, having in mind that the literature of Economics of Technology, and its regional approach, emphasize that the mobility of qualified workers is important to transfer tacit knowledge among regions, with strong repercussion on the possibility of regional development. In this dialog, theorical concepts that treat questions linked to the capacity of qualified workers to transfer technological knowledge when they move are established, improving the development. With the use of microdata from RAIS Migra (MTE), a sample of workers employed on the industry are followed eight years long (1995-2002), and the composition of the formal employment in Brazil divided in sectors with different levels of technological intensity are presented. Using multinomial logistic regression models, this paper reveals that the mobility is positively related to the wages, to the male gender and to the educational level of the workers. And it is negatively related to their level of seniority. Besides, all these results are significantly different when the territorial extension of the mobility is considered, what is possible to see through the use of the multinomial methodology.

Övervakad maskininlärning har gett goda resultat för automatisk namntaggning. Detta kräver dock manuellt annoterad träningsdata, vilket är krävande att ta fram. Studier har visat att likhet mellan träningsdata och testdata är viktigt för att uppnå bra resultat, men normalt sett tränas system alltid med så mycket data som möjligt, utan hänsyn till dess relevans. Syftet med denna studie är att undersöka om bättre namntaggning kan uppnås genom att utesluta de delar av träningsdatan som inte tillhör samma textdomän som testdatan. För att genomföra detta konstrueras ett system med multinomial logistisk regression som tränas och testas på Stockholm-Umeå Corpus enligt både traditionell och föreslagen metod. Undersökningen visar en liten men signifikant försämring vid användning av enbart domänspecifik träningsdata, ett resultat som dock inte är genomgående för alla delar av undersökningen. Den stora fördelen av att reducera träningsdatan är dock att det ökar maskininlärningens hastighet. För att kunna utnyttja detta föreslås att namntaggning föregås av textklassificering.

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Reflecting the growing interest from both consumers and policymakers, and building on recent developments in Willingness to Pay (WTP) methodologies, we evaluate consumer preferences for an archetypal traditional food product. Specifically we draw on stated preference data from a discrete choice experiment, considering the traditional Hungarian mangalitza salami. A WTP space specification of the generalized multinomial logit model is employed, which accounts for not only heterogeneity in preferences but also differences in the scale of the idiosyncratic error term. Results indicate that traditional food products can command a substantial premium, albeit contingent on effective quality certification, authentic product composition and effective choice of retail outlet. Promising consumer segments and policy implications are identified. (authors' abstract)

This study had two main objectives. One objective was to measure the aggregate impact of climate change on income from all agricultural production systems (crop, livestock and mixed) in Africa and to predict future impacts under various climate scenarios. In addition to measuring economic impacts, the study analysed determinants of farmers’ choices between alternative adaptation measures available to African farmers. The study is based on a cross-section survey of over 8000 farming households from 11 countries in east, west, north and southern Africa. To achieve the first objective, the cross-section (Ricardian) approach was used to measure the impact of climate change attributes (rainfall and temperature levels) on income from all agricultural production systems (crop, livestock and mixed) in Africa, controlling for other production factors. Based on empirical estimates from the Ricardian model, the study predicts future impacts under various climate scenarios. In addition to estimating impacts on mixed croplivestock farms, the study also measures and compares impacts on specialised crop and livestock farms. Responses of different production systems are analysed under irrigation and dryland conditions. The response of net revenue from crop and livestock agriculture across various farm types and systems in Africa, to changes in climate variables (i.e. mean rainfall and temperature) is analysed. The analysis controlled for effects of key socio-economic, technology, soil and hydrological factors influencing agricultural production. In addition to measuring impacts on aggregate revenue, the study examined variations in the response of three distinct production systems characterising African agriculture: specialised crop; specialised livestock and mixed crop and livestock systems. Differential impacts of climate change on the studied systems were measured under irrigation and dryland conditions. Results show that net farm revenues are in general negatively affected by warmer and dryer climates. The mixed crop and livestock system predominant in Africa is the most tolerant, whereas specialised crop production is the most vulnerable to warming and lower rainfall. These results have important policy implications, especially in terms of the suitability of the increasing tendency toward mono-cropping strategies for agricultural development in Africa and other parts of the developing world, in the light of expected climate changes. Mixed crop and livestock farming and irrigation offered better adaptation options for farmers against further warming and drying predicted under various future climate scenarios. For the second objective, the study employed a multinomial choice model to analyse determinants of farm-level climate adaptation measures in Africa. Results indicate that specialised crop cultivation (mono-cropping) is the most vulnerable agricultural practice in Africa in the face of climate change. Warming, especially in summer, poses the highest climate risk which tends to indicate switching away from mono-cropping towards the use of irrigation, multiple cropping and integration of livestock activities. Increased precipitation reduces the need for irrigation and will be beneficial to most African farming systems, especially in drier areas. Better access to markets, agricultural extension and credit services, technology and farm assets (such as labour, land and capital) are critical enabling factors to enhance the capacity of African farmers to adapt to climate change. Government policies and investment strategies that support the provision of and access to education, markets, credit, and information on climate and adaptation measures, including suitable technological and institutional mechanisms that facilitate climate adaptation, are therefore required for coping with climate change, particularly among poor resource farmers in the dry areas of Africa. / Thesis (PhD)--University of Pretoria, 2009. / Agricultural Economics, Extension and Rural Development / unrestricted

This thesis is focused on sentiment analysis of unstructured text and its practical application on the real data downloaded from website Yelp.com The objectives of the theoretical part of this thesis is to sum up the information related to history, methods and possible applications of sentiment analysis. A reader is acquainted with important terms and processes of sentiment analysis. Theoretical part is focused on Naive Bayes classifier, that will be used in practical part of this thesis. In practical part there is detailed description of data set, construction and testing of model. At the end there are presented pros and cons of the chosen model and described some possibilities of its usage.