The general objectives of the present thesis were to evaluate: (i) the effects of subclinical mastitis (SM) caused by major pathogens on SCC, milk leukocyte differentials (MLD) and milk yield; (ii) milk yield losses caused by SM at the cow and quarter level; and (iii) the economic impact of SM caused by major pathogens. The thesis was structured in four studies. In study 1, quarter milk samples (n = 302) from 78 cows with SCC gt;200,000 cells/mL were analyzed by milk leukocyte differential (MLD) methodology and by microbiological culture (MC). Quarters with positive-culture results were obtained from 102/156 (65.4%) of MLD-positive milk samples, while 28/135 (20.7%) of MLD-negative milk samples were MC-positive. When MC was considered the gold standard for mastitis diagnosis, the sensitivity (Se) of the MLD was 65.4% (IC95% = 57.4 to 72.8%) and the specificity (Sp) was 79.3% (IC95% = 71.4% to 85.7%). In conclusion, the use of the MLD on cows with monthly composite SCC > 200×103 cells/mL for screening at quarter level identified quarters more likely to be culture-positive. In study 2, the effect of different pathogens was evaluated by comparison of contralateral (healthy and infected) mammary quarters of 146 lactating cows. The impact of SM on economic return (quarter milk yield × milk price) was determined by applying milk payment estimates on milk collected from healthy versus infected glands. The milk losses ranged from 0.07 Kg/quarter.milking to 2.9 Kg/quarter.milking, and varied according to the pathogen causing SM. Economic losses were higher for SM caused by Enterococcus spp. (US$0.43/quarter.milking), Strep. Dysgalactiae (US$ 0.74/quarter.milking) and E. coli (US$0.98/quarter.milking). Additionally, there was a trend for Staph. aureus and Citrobacter spp. To induce economic losses of US$ 0.26 and 0.29/quarter.milking, respectively. In general, the economic return was lower in quarters with SM caused by environmental and contagious pathogens (US$ 0.18 and 0.22/quarter.milking, respectively) when compared to their healthy contralateral quarters. In study 3, a total of 146 out of 650 lactating cows were selected from seven dairy herds for having composite milk SCC > 200,000 cells/mL in combination with the isolation of a major mastitis pathogen. From these selected cows, 1,436 quarter milk samples were collected during three successive sampling occasions at intervals of 15-20 days. Quarter milk yield was measured by milking the mammary quarters individually using three successive milk samplings over time. Bacterial isolates were identified by microbiological culture, MALDI-TOF MS and partial sequencing of the 16S rRNA gene. Milk losses and economic returns varied according to the type of mastitis-causing pathogen: 0.24 to -0.87 kg/quarter.milking for environmental streptococci, and -1.57 to -1.69 kg/quarter.milking for Staph. aureus. Overall, mammary quarters that were cured from SM caused by Staph. aureus and environmental streptococci exhibited an increase in economic return of approximately 0.47 and 0.69 US$/quarter.milking, respectively. In study 4, test day records (n = 1,200,002) were obtained from the Paraná State Holstein Association, which included data from 92,560 lactating cows, from 781 herds, from January 2010 to December 2015. A segmented regression was fitted to estimate the cut-off point of Log10SCC scale where milk yield started to be affected by mastitis: 0.90 (~7,963 cells/mL). In conclusion, first lactation cows have a reduction of 1.37 to 2.28 kg/cow/d of milk yield for each increase of one unit of Log10SCC over the cutoff point, whereas second and later lactation cows are expected to have milk yield losses of 2.36 to 4.20 kg/cow/d for each unit increase of Log10SCC over the cutoff point. Overall, the results of this thesis indicated that milk losses depend on the type of pathogen causing SM. Major pathogens have showed greater effects on milk quality than when it was observed using the approach of culture results of negative or positive. The methodology for evaluation of subclinical mastitis effect on milk yield interferes in the estimation of milk losses, and should include factors such as DIM and number of parity. / Os objetivos gerais da tese foram avaliar: (i) os efeitos da mastite subclínica (MS) causada por patógenos primários sobre a CCS, contagem diferencial de células e produção de leite; (ii) perdas de produção de leite ocasionadas pela MS, em nível de vacas e quartos mamários; e (iii) o impacto econômico da MS causado por patógenos primários. A tese foi estruturada em quatro estudos. No estudo 1, amostras de leite de quartos mamários (n = 302) foram submetidas a cultura microbiológica (CM) e contagem diferencial de leucócitos (MLD). Quartos com resultados cultura-positiva apresentaram 102/156 (65,4%) amostras de leite MLD-positivas, e 28/135 (20,7%) das amostras de leite MLD-negativas tiveram CM-positivas. Quando a CM foi considerada o padrão-ouro para o diagnóstico da mastite, o diagnóstico por meio da MLD apresentou sensibilidade (Se) de 65,4% (IC95% = 57,4 a 72,8%) e especificidade (Sp) de 79,3% (IC95% = 71,4% a 85,7%). Em conclusão, o uso da MLD em vacas com CCS mensal > 200,000 células/mL para triagem de quartos identificou os mais prováveis de ser cultura-positivos. No estudo 2, o efeito de diferentes tipos de patógenos foi estudado avaliando pares de quartos mamários contralaterais (sadios e infectados) de 146 vacas em lactação. O impacto da MS sobre o retorno econômico (produção de leite × preço do leite) foi determinado pela aplicação de estimativas de pagamento do leite de quartos sadios e infectados. As perdas de leite variaram de 0,07 Kg/quarto.ordenha a 2,9 Kg/quarto.ordenha de acordo com o patógeno causador de MS. As perdas econômicas foram maiores em casos de MS causados por Enterococcus spp. (US$ 0,43/quarto.ordenha), Strep. dysgalactiae (US$ 0,74/quarto.ordenha) e E. coli (US$ 0,98/quarto.ordenha). Além disso, houve uma tendência de Staph. aureus e Citrobacter spp. ocasionar perdas de US$ 0,26 e 0,29/quarto.ordenha, respectivamente. Em geral, o retorno econômico foi menor em quartos com MS causada por patógenos ambientais e contagiosos (US$ 0,18 e 0,22/quarto.ordenha, respectivamente) quando comparados com os quartos contralaterais sadios. No estudo 3, um total de 146 das 650 vacas em lactação foram selecionadas de sete rebanhos por apresentar amostras compostas de leite com alta CCS (> 200.000 células/mL) e isolamento de patógeno primário causador de MS. Destas vacas selecionadas, 1.436 amostras de leite de quartos foram coletadas durante três amostragens sucessivas com intervalos de 15-20 dias. A produção de leite em nível de quartos mamários foi mensurada por meio de ordenha completa e individual. Os isolados bacterianos foram identificados por CM, MALDI-TOF MS e sequenciamento parcial do gene 16S rRNA. As perdas de leite e os retornos econômicos variaram de acordo com o tipo de patógeno causador da mastite: - 0,24 a -0,87 kg/quarto.ordenha (Streptococcus ambientais) e -1,57 a -1,69 kg/quarto.ordenha (Staph. aureus). Em geral, os quartos mamários que apresentaram cura da MS causada por Staph. aureus e Streptococcus ambientais apresentaram aumento no retorno econômico de aproximadamente 0,47 e 0,69 US$/quarto.ordenha, respectivamente. No estudo 4, registros do controle leiteiro (n = 1.200.002) foram obtidos da associação Paranaense do gado Holandês, os quais incluíram dados de 92.560 vacas Holandesas em lactação de 781 rebanhos, de janeiro de 2010 a dezembro de 2015. Uma regressão segmentada foi ajustada para estimar o ponto de corte na escala Log10CCS em que a produção de leite começou a ser afetada pela MS: 0.90 (~ 7.963 células/mL). Como conclusão, vacas de primeira cria apresentaram redução de 1,37 a 2,28 kg/vaca/dia na produção de leite para cada aumento de uma unidade Log10CCS acima do ponto de corte, enquanto vacas com duas ou mais crias apresentaram perdas de 2,36 a 4,20 kg/vaca/dia. Em geral, os resultados desta tese indicaram que as perdas de leite dependem do tipo de patógeno que causa SM. Os patógenos primários mostraram maiores efeitos sobre a qualidade do leite do que quando foram observados pela abordagem com base nos resultados de cultura negativa ou positivos. A metodologia de avaliação do efeito da mastite subclínica sobre a produção de leite interfere na estimativa das perdas de leite e deve incluir fatores como DIM e número de paridade.

Em tarefas de tempo de reação, uma pista visual pode engatilhar diversos processos, que facitam ou inibem diferentes estágios do processamento do estímulo-alvo. As características da tarefa podem modular os efeitos da pista. Neste estudo, investigamos as possíveis causas dos efeitos inibitórios da pista. Em experimentos em que foi usada uma tarefa de discriminação vai/não-vai, um efeito inibitório foi encontrado quando um valor fixo assincronia entre o início pista e o início do estímulo-alvo (SOA) foi usado, mas não quando o valor de SOA foi variado no decorrer da tarefa. Na tarefa de discriminação de escolha, nenhum efeito initório da pista foi observado, enquanto na tarefa de detecção houve facilitação. Nós propomos que o efeito inibitório na tarefa do tipo vai-não/vai se origina da inibição da tendência de responder automaticamente ao aparecimento da pista. Essa inibição tornaria mais lenta a resposta ao estímulo-alvo subsequente. / In reaction time tasks, a visual cue can trigger several processes and each of these processes can have either a facilitatory or inhibitory influence on different stages of target processing. It has been suggested that task set might modulate cuing effects. In the present study, we investigated the possible causes of inhibitory cueing effects. In experiments involving a go/no-go discrimination task, an inhibitory cueing effect on reaction time was found when a fixed asynchrony between cue onset and target onset (SOA) was used, but not when varied SOAs was used. In a choice discrimination task no inhibitory cueing effect was observed, while in a detection task there was a facilitatory cueing effect. We propose that the inhibitory cueing effect in the go/no-go task arises from the inhibition of an automatic tendency to respond to the cue. This would slow responding to the subsequent target stimulus. Our results suggest that a response inhibition to the cue may contribute to the inhibition of return effect.

by King-fai Tam. / Bibliography: leaves 151-158 / Thesis (M.Phil.)--Chinese University of Hong Kong, 1983

Mak Wing Hei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 50-52). / Abstracts in English and Chinese. / ABSTRACT --- p.1 / 摘要 --- p.2 / ACKNOWLEDGEMENTS --- p.3 / TABLE OF CONTENTS --- p.4 / Chapter CHAPTER 1 --- INTRODUCTION & LITERATURE REVIEW --- p.6 / Chapter CHAPTER 2 --- DATA DESCRIPTION --- p.12 / Chapter 2.1 - --- Coverage and Sources --- p.12 / Chapter 2.2 - --- Match Accounting Data with Stock Returns --- p.12 / Chapter 2.3 - --- Selection Rule --- p.13 / Chapter 2.4 - --- Choice of the Threshold Variables Z --- p.14 / Chapter CHAPTER 3 --- THE MODEL --- p.15 / Chapter 3.1 - --- Estimating excess returns & Betas --- p.15 / Chapter 3.2- --- Estimating Threshold Effects --- p.17 / Chapter 3.3 - --- Testing the Number of Threshold Variables --- p.19 / Chapter 3.4 - --- Estimating Threshold values --- p.21 / Chapter CHAPTER 4 --- PRELIMINARY OBSERVATIONS --- p.21 / Chapter 4.1 - --- Excess Returns --- p.21 / Chapter 4.2 - --- "Relationship between Beta, Market Size and Book-to-Market Equity" --- p.24 / Chapter CHAPTER 5 --- ESTIMATION RESULTS OF THE THRESHOLD MODEL --- p.35 / Chapter 5.1 - --- Number of Threshold Variables --- p.35 / Chapter 5.2- --- Threshold Value Estimates --- p.39 / Chapter 5.3- --- The “and´ح case and “or´حcase --- p.40 / Chapter 5.4 - --- Comparison with OLS --- p.45 / Chapter CHAPTER 6 --- CONCLUSION --- p.48 / REFERENCES --- p.50

One major criticism about the traditional mean-variance portfolio optimization is that it tends to magnify the estimation error. A little estimation error can cause the distortion of the whole portfolio. Two popular ways to solve this problem are to use a resampling method or the Black-Litterman method (Bayesian method). The clustering method is a newer way to solve the problem. Clustering means we group the highly correlated stocks first and treat the group as a single stock. After we group the stocks, we will have some clusters of stocks, then we run the traditional mean-variance portfolio optimization for these clusters. The clustering method can improve the stability of the portfolio and reduce the impact of estimation error. In this project, we will explain why it works and we will perform tests to determine if clustering methods do improve the stabilities and performance of the portfolio.

Essa pesquisa tem como tema central a História Oral de Vida de imigrantes libaneses e seus descendentes nascidos no Brasil, bem como de brasileiras não-descendentes, que empreenderam o retorno ao Líbano, cujo fluxo foi verificado com maior intensidade ao final da década de 1980. A problemática geral dessa pesquisa é verificar e analisar a concretização do retorno, a partir da análise dos fenômenos de readaptação e adaptação, reinserção e inserção, destacando-se as dificuldades, os dilemas e os conflitos decorrentes desse ato. Mais do que a ocupação de um espaço geográfico, devemos considerar que o retorno e restabelecimento nos vilarejos de origem significam uma apropriação (ou criação) cultural do lugar (aqui entendido em sua dimensão subjetiva), construindo-se sentimentos de identidade, de pertencimento ao grupo que, por meio de suas ações, controlam e influenciam pessoas, estabelecem relações, determinam valores e normas a serem seguidas. Considerando identidade e cultura como processos dinâmicos, em constante elaboração e reelaboração, há que se verificar que a reinserção e inserção ao país implicarão renúncias, escolhas e seleções, que serão negociadas pelo migrante em relação ao grupo de origem. / This research has as central subject the Oral History of Lebanese immigrants and their descendants borned in Brazil, as well as of Brazilians not-descendants, who had undertaken the return to the Lebanon, whose flow was verified with more intensity to the end of 1980\'s. The general problematic of this research is to verify the achievement of the return, from the analysis of the phenomena of readjustment and adaptation, (re) insertion and insertion, in order to distinguish the difficulties, the dilemmas and the decurrent conflicts of this act. More than the occupation of a geographic space, we must consider that the return and reestablishment in the villages of origin mean a cultural appropriation (or creation) of the place (understood here in its subjective dimension), constructing identity feelings, belonging to the group that, by of its action, controls and influences people, establishes relations, determines values and norms to be followed. Considering identity and culture as dynamic processes, in constant elaboration and rework, it is important to verify that the (re) insertion and insertion to the country will imply resignations, choices and elections, that will be negotiated by the migrant in relation to the group of origin.

As estratégias construtivistas na obra de Hélio Oiticica estão compreendidas na noção definida pelo artista de \"mundo erigindo mundo\". Esta estratégia é identificável tanto nos aspectos éticos e estéticos das proposições de Oiticica quanto na maneira como seu próprio pensamento é construído de blocos achados nas obras de filósofos, músicos e outros artistas. Este trabalho percorre manuscritos de Hélio Oiticica disponíveis em arquivos digitais para identificar os blocos de pensamento que embasam a produção de Hélio Oiticica, identificando a singularidade de sua obra frente a propostas de alguns de seus contemporâneos. Ainda que reconhecendo a importância do mito e da Mangueira na obra do inventor da Tropicália, o texto enfatiza que a \"síntese\" feita por Hélio Oiticica não se deixa fixar em um estereótipo cultural já que escapa dos espaços delimitados e do tempo cronológico, estabelecendo-se em um \"mundo-abrigo\" virtual, onde Oiticica acha fragmentos das produções de inventores de vários lugares e épocas para compor seu programa além-da-arte. / The constructivist strategies within Hélio Oiticica´s oeuvre are comprehended in the notion of \"world building world\" articulated by the artist. This strategy is discernible both on the ethic and aesthetic aspects of Oiticica´s proposals and on the way his own thought is built out of blocks he found in works by philosophers, musicians and other artists. This text traverses manuscripts by Hélio Oiticica, available in digital archives, to identify the building blocks of the artist´s thought and its singularity in relation to proposals of some of his contemporaries. Although recognizing the importance of the myth and of the Mangueira samba school on the work of the inventor of Tropicalia, this text emphasizes that the \"synthesis\" produced by Hélio Oiticica defies cultural stereotypes since it escapes boundaries and the chronological time, establishing itself within a \"world-shelter\" where the artist finds fragments of the production of other inventors from different cultures and times, to compose his own beyond-the-art program.

Os analistas de ações desempenham um papel relevante nos mercados de capitais, na medida em que, direta ou indiretamente, contribuem para a precificação dos papéis e para a composição das carteiras de investimentos. A proposta deste estudo foi a de verificar se é possível obter retornos extraordinários, acima daqueles oferecidos por uma carteira de mercado, com o acompanhamento das recomendações de ações emitidas por analistas do mercado de capitais brasileiro. Com base em uma ampla gama de recomendações consensuais referentes ao período que abrangeu os anos de 2000 a 2010, e com o acompanhamento das séries históricas de retornos dos papéis cobertos pelas análises, foram comparados os desempenhos de duas carteiras, uma formada por ações que receberam recomendações favoráveis e outra formada por ações que receberam recomendações desfavoráveis dos analistas. Os resultados mostraram a existência de um viés nas recomendações, dado que há, sistematicamente, um número maior de favoráveis frente às recomendações desfavoráveis. E mostraram, principalmente, que os analistas não foram capazes de identificar as ações que efetivamente ofereceram maiores retornos ao longo do período considerado. / The stock analysts have a relevant role in the capital markets, because, directly or indirectly, they contribute to the paper pricing and to the composition of the investment portfolio. The proposal of this study was to verify if it is possible to obtain extraordinary returns, above those offered by a market portfolio, with the monitoring of the stock recommendations issued by Brazilian capital market analysts. Based on a wide range of consensual recommendations concerning the period from 2000 to 2010, and with the historical series of return of the monitoring of the historical series of paper returns covered by the analyses, the performance of two portfolios, one formed by stocks that received favorable recommendations and the other one formed by stocks that received unfavorable recommendations of the analysts. The results showed the existence of biases in the recommendation, since there is, systematically, a greater number of favorable against unfavorable recommendations. They also showed that, mainly, the analysts were unable to identify the stocks which actually offered greater returns within the period considered.

This thesis consists of one stock return predictability study and two international risk exposure studies. The first study shows that the statistical significance of out-of-sample predictability of market returns given by Kelly and Pruitt (2013), using a partial least squares methodology, constructed from the valuation ratios of portfolios, is overstated for two reasons. Firstly, the analysis is conducted on gross returns rather than excess returns, and this raises the apparent predictability of the equity premium due to the inclusion of predictable movements of interest rates. Secondly, the bootstrap statistics used to assess out-of-sample significance do not account for small-sample bias in the estimated coefficients. This bias is well known to affect in-sample tests of significance and I show that it is also important for out-of-sample tests of significance. Accounting for both these effects can radically change the conclusions; for example, the recursive out-of-sample R2 values for the sample period 1965-2010 are insignificant for the prediction of one-year excess returns, and one-month returns, except in the case of the book-to-market ratios of six size- and value-sorted portfolios which are significant at the 10% level. The second study examines whether U.S. common stocks are exposed to international risks, which I define as shocks to foreign markets that are orthogonal to U.S. market returns. By sorting stocks on past exposure to this risk factor I show that it is possible to create portfolios with an ex-post spread in exposure to international risk. I examine whether the international risk is priced in the cross-section of U.S. stocks, and find that for small stocks an increase in exposure to international risk results in lower returns relative to the Fama-French three-factor model. I conduct similar analysis on a measure of the international value premium and find little evidence of this risk being priced in U.S. stocks. The third study examines whether a portfolios of U.S. stocks can mimic foreign index returns, thereby providing investors with the benefits of international diversification without the need to invest directly in assets that trade abroad. I test this proposition using index data from seven developed markets and eight emerging markets over the period 1975-2013. Portfolios of U.S. stocks are constructed out-of-sample to mimic these international indices using a step-wise procedure that selects from a variety of industry portfolios, stocks of multinational corporations, country funds and American depositary receipts. I also use a partial least squares approach to form mimicking portfolios. I show that investors are able to gain considerable exposure to emerging market indices using domestically traded stocks. However, for developed market indices it is difficult to obtain home-made exposure beyond the simple exposure of foreign indices to the U.S. market factor. Using mean-variance spanning tests I find that, with few exceptions, international indices do not improve over the investment frontier provided by the domestically constructed alternative of investing in the U.S. market index and portfolios of industries and multinational corporations.

Sen Sui. / Thesis submitted in: August 2003. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 88-92). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgement --- p.iv / Dedication --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation and Objective --- p.1 / Chapter 1.2 --- Contributions --- p.4 / Chapter 1.3 --- Thesis Organization --- p.5 / Chapter 2 --- Background of Risk Management --- p.7 / Chapter 2.1 --- Measuring Return --- p.8 / Chapter 2.2 --- Objectives of Risk Measurement --- p.11 / Chapter 2.3 --- Simple Statistics for Measurement of Risk --- p.15 / Chapter 2.4 --- Methods for Value-at-Risk Measurement --- p.16 / Chapter 2.5 --- Conditional VaR --- p.18 / Chapter 2.6 --- Portfolio VaR Methods --- p.18 / Chapter 2.7 --- Coherent Risk Measure --- p.20 / Chapter 2.8 --- Summary --- p.22 / Chapter 3 --- Selection of Independent Factors for VaR Computation --- p.23 / Chapter 3.1 --- Mixture Convolution Approach Restated --- p.24 / Chapter 3.2 --- Procedure for Selection and Evaluation --- p.26 / Chapter 3.2.1 --- Data Preparation --- p.26 / Chapter 3.2.2 --- ICA Using JADE --- p.27 / Chapter 3.2.3 --- Factor Statistics --- p.28 / Chapter 3.2.4 --- Factor Selection --- p.29 / Chapter 3.2.5 --- Reconstruction and VaR Computation --- p.30 / Chapter 3.3 --- Result and Comparison --- p.30 / Chapter 3.4 --- Problem of Using Kurtosis and Skewness --- p.40 / Chapter 3.5 --- Summary --- p.43 / Chapter 4 --- Mixture of Gaussians and Value-at-Risk Computation --- p.45 / Chapter 4.1 --- Complexity of VaR Computation --- p.45 / Chapter 4.1.1 --- Factor Selection Criteria and Convolution Complexity --- p.46 / Chapter 4.1.2 --- Sensitivity of VaR Estimation to Gaussian Components --- p.47 / Chapter 4.2 --- Gaussian Mixture Model --- p.52 / Chapter 4.2.1 --- Concept and Justification --- p.52 / Chapter 4.2.2 --- Formulation and Method --- p.53 / Chapter 4.2.3 --- Result and Evaluation of Fitness --- p.55 / Chapter 4.2.4 --- Evaluation of Fitness using Z-Transform --- p.56 / Chapter 4.2.5 --- Evaluation of Fitness using VaR --- p.58 / Chapter 4.3 --- VaR Estimation using Convoluted Mixtures --- p.60 / Chapter 4.3.1 --- Portfolio Returns by Convolution --- p.61 / Chapter 4.3.2 --- VaR Estimation of Portfolio Returns --- p.64 / Chapter 4.3.3 --- Result and Analysis --- p.64 / Chapter 4.4 --- Summary --- p.68 / Chapter 5 --- VaR for Portfolio Optimization and Management --- p.69 / Chapter 5.1 --- Review of Concepts and Methods --- p.69 / Chapter 5.2 --- Portfolio Optimization Using VaR --- p.72 / Chapter 5.3 --- Contribution of the VaR by ICA/GMM --- p.76 / Chapter 5.4 --- Summary --- p.79 / Chapter 6 --- Conclusion --- p.80 / Chapter 6.1 --- Future Work --- p.82 / Chapter A --- Independent Component Analysis --- p.83 / Chapter B --- Gaussian Mixture Model --- p.85 / Bibliography --- p.88