Development of land rental market and its effect on household farming in rural China : an empirical study in Zhejiang Province

This paper investigates the impact of land rental market development on the efficiency of labor allocation and land utilization in rural China. To test the hypothesis that the shadow wage of a rent-in household with limited off-farm opportunities will increase with the development of a land rental market for households, a statistical comparison between the shadow wage and the estimated market wage was conducted. The results showed that the shadow wage for both rent-in households and non-rent-in households was significantly lower than the market wage, but that the wage for the rent-in households was statistically higher than that for non-rent-in households in Fenghua and Deqing, the two counties surveyed in this study. In addition, the estimated marginal product of farmland for rent-in households was statistically higher than the actual land rent that those households paid, while a null hypothesis that the actual rental fee accepted by rent-out households is equivalent to the marginal product of farmland for those households was not rejected in Fenghua county where land transactions by mutual agreement were more prevalent. These results indicate that the development of the land rental market facilitates the efficiency of labor allocation and farmland utilization in rural China.

Random positions of dendritic spines in human cerebral cortex

Dendritic spines establish most excitatory synapses in the brain and are located in Purkinje cell’s dendrites along helical paths, perhaps maximizing the probability to contact different axons. To test whether spine helixes also occur in neocortex, we reconstructed >500 dendritic segments from adult human cortex obtained from autopsies. With Fourier analysis and spatial statistics, we analyzed spine position along apical and basal dendrites of layer 3 pyramidal neurons from frontal, temporal, and cingulate cortex. Although we occasionally detected helical positioning, for the great majority of dendrites we could not reject the null hypothesis of spatial randomness in spine locations, either in apical or basal dendrites, in neurons of different cortical areas or among spines of different volumes and lengths. We conclude that in adult human neocortex spine positions are mostly random. We discuss the relevance of these results for spine formation and plasticity and their functional impact for cortical circuits.

Random positioning of dendritic spines in the human cerebral cortex

Dendritic spines establish most excitatory synapses in the brain and are located in Purkinje cell?s dendrites along helical paths, perhaps maximizing the probability to contact different axons. To test whether spine helixes also occur in neocortex, we reconstructed ?500 dendritic segments from adult human cortex obtained from autopsies. With Fourier analysis and spatial statistics, we analyzed spine position along apical and basal dendrites of layer 3 pyramidal neurons from frontal, temporal, and cingulate cortex. Although we occasionally detected helical positioning, for the great majority of dendrites we could not reject the null hypothesis of spatial randomness in spine locations, either in apical or basal dendrites, in neurons of different cortical areas or among spines of different volumes and lengths. We conclude that in adult human neocortex spine positions are mostly random. We discuss the relevance of these results for spine formation and plasticity and their functional impact for cortical circuits.

O Conflito de Agência Exposto ao Efeito de Mercado: Um Estudo Empírico de Precificação de Ações da Bombril S/A

Esta dissertação apresenta um estudo exploratório que tem como objetivo a avaliação da reação do mercado frente aos problemas de agência e assimetria informacional entre os acionistas majoritários-controladores e os acionistas minoritários de uma empresa brasileira de capital aberto, no tocante ao valor das suas ações negociadas na Bolsa de Valores de São Paulo. O estudo se propõe a investigar o impacto de precificação dessas ações promovendo a análise do seu comportamento frente à divulgação de notícias de crise e fraude da empresa por meio da mídia especializada. A metodologia adotada consiste na aplicação de estudo de eventos para identificação de retornos anormais da empresa desde a divulgação da primeira notícia selecionada, datada de maio de 2001, até a última notícia em outubro de 2005, utilizando-se de procedimentos estatísticos como a regressão linear e aplicação do teste t de student para estimar e comparar os resultados. Os dados foram obtidos por meio do banco de dados da Economática Ltda, conforme acesso realizado na Universidade de São Paulo. Para objeto de pesquisa foi selecionada a empresa Bombril S/A, por estar em evidências quanto a problemas de agência no âmbito do mercado nacional. Os resultados obtidos apontaram que o mercado reagiu significantemente aos anúncios dos conflitos selecionados, apresentando um valor de p-value <0,05 para os blocos de eventos, o que significa a rejeição da hipótese nula, constatando que a evidencia estatística dos dados testados comprova retornos anormais acumulados diferentes de zero. Entretanto, sugere-se novas pesquisas com outros parâmetros de eventos na busca de mais evidências sobre o efeito das informações no preço das ações.

O Conflito de Agência Exposto ao Efeito de Mercado: Um Estudo Empírico de Precificação de Ações da Bombril S/A

Esta dissertação apresenta um estudo exploratório que tem como objetivo a avaliação da reação do mercado frente aos problemas de agência e assimetria informacional entre os acionistas majoritários-controladores e os acionistas minoritários de uma empresa brasileira de capital aberto, no tocante ao valor das suas ações negociadas na Bolsa de Valores de São Paulo. O estudo se propõe a investigar o impacto de precificação dessas ações promovendo a análise do seu comportamento frente à divulgação de notícias de crise e fraude da empresa por meio da mídia especializada. A metodologia adotada consiste na aplicação de estudo de eventos para identificação de retornos anormais da empresa desde a divulgação da primeira notícia selecionada, datada de maio de 2001, até a última notícia em outubro de 2005, utilizando-se de procedimentos estatísticos como a regressão linear e aplicação do teste t de student para estimar e comparar os resultados. Os dados foram obtidos por meio do banco de dados da Economática Ltda, conforme acesso realizado na Universidade de São Paulo. Para objeto de pesquisa foi selecionada a empresa Bombril S/A, por estar em evidências quanto a problemas de agência no âmbito do mercado nacional. Os resultados obtidos apontaram que o mercado reagiu significantemente aos anúncios dos conflitos selecionados, apresentando um valor de p-value <0,05 para os blocos de eventos, o que significa a rejeição da hipótese nula, constatando que a evidencia estatística dos dados testados comprova retornos anormais acumulados diferentes de zero. Entretanto, sugere-se novas pesquisas com outros parâmetros de eventos na busca de mais evidências sobre o efeito das informações no preço das ações.

Y chromosome polymorphism is a strong determinant of male fitness in Drosophila melanogaster

In many species, the Y (or W) chromosome carries relatively few functional genes. This observation motivates the null hypothesis that the Y will be a minor contributor to genetic variation for fitness. Previous data and theory supported the null hypothesis, but evidence presented here shows that the Y of Drosophila melanogaster is a major determinant of a male's total fitness, with standing genetic variation estimated to be 68% of that of an entire X/autosome genomic haplotype. Most Y-linked genes are expressed during spermatogenesis, and correspondingly, we found that the Y influences fitness primarily through its effect on a male's reproductive success (sperm competition and/or mating success) rather than his egg-to-adult viability. But the fitness of a Y highly depended on the genetic makeup of its bearer, reverting from high to low in different genetic backgrounds. This pattern leads to large epistatic (inconsistent among backgrounds) but no additive (consistent among backgrounds) Y-linked genetic variance for fitness. On a microevolutionary scale, the observed large epistatic variation on the Y substantially reduces heritable variation for fitness among males, and on a macroevolutionary scale, the Y produces strong selection for genomic rearrangements that move interacting genes onto the nonrecombining region of the Y.

Adaptive designs in the time to event setting: The potential for benefit and risk

Thesis (Ph.D.)--University of Washington, 2016-06

A theory for optimal monitoring of marine reserves

Monitoring of marine reserves has traditionally focused on the task of rejecting the null hypothesis that marine reserves have no impact on the population and community structure of harvested populations. We consider the role of monitoring of marine reserves to gain information needed for management decisions. In particular we use a decision theoretic framework to answer the question: how long should we monitor the recovery of an over-fished stock to determine the fraction of that stock to reserve? This exposes a natural tension between the cost (in terms of time and money) of additional monitoring, and the benefit of more accurately parameterizing a population model for the stock, that in turn leads to a better decision about the optimal size for the reserve with respect to harvesting. We found that the optimal monitoring time frame is rarely more than 5 years. A higher economic discount rate decreased the optimal monitoring time frame, making the expected benefit of more certainty about parameters in the system negligible compared with the expected gain from earlier exploitation.

Genetic time-series analysis identifies a major QTL for in vivo alcohol metabolism not predicted by in vitro studies of structural protein polymorphism at the ADH1B or ADH1C loci

After ingestion of a standardized dose of ethanol, alcohol concentrations were assessed, over 3.5 hours from blood (six readings) and breath (10 readings) in a sample of 412 MZ and DZ twins who took part in an Alcohol Challenge Twin Study (ACTS). Nearly all participants were subsequently genotyped on two polymorphic SNPs in the ADH1B and ADH1C loci known to affect in vitro ADH activity. In the DZ pairs, 14 microsatellite markers covering a 20.5 cM region on chromosome 4 that includes the ADH gene family were assessed, Variation in the timed series of autocorrelated blood and breath alcohol readings was studied using a bivariate simplex design. The contribution of a quantitative trait locus (QTL) or QTL's linked to the ADH region was estimated via a mixture of likelihoods weighted by identity-by-descent probabilities. The effects of allelic substitution at the ADH1B and ADH1C loci were estimated in the means part of the model simultaneously with the effects sex and age. There was a major contribution to variance in alcohol metabolism due to a QTL which accounted for about 64% of the additive genetic covariation common to both blood and breath alcohol readings at the first time point. No effects of the ADH1B*47His or ADH1C*349Ile alleles on in vivo metabolism were observed, although these have been shown to have major effects in vitro. This implies that there is a major determinant of variation for in vivo alcohol metabolism in the ADH region that is not accounted for by these polymorphisms. Earlier analyses of these data suggested that alcohol metabolism is related to drinking behavior and imply that this QTL may be protective against alcohol dependence.

A time-domain test for some types of nonlinearity

The bispectrum and third-order moment can be viewed as equivalent tools for testing for the presence of nonlinearity in stationary time series. This is because the bispectrum is the Fourier transform of the third-order moment. An advantage of the bispectrum is that its estimator comprises terms that are asymptotically independent at distinct bifrequencies under the null hypothesis of linearity. An advantage of the third-order moment is that its values in any subset of joint lags can be used in the test, whereas when using the bispectrum the entire (or truncated) third-order moment is required to construct the Fourier transform. In this paper, we propose a test for nonlinearity based upon the estimated third-order moment. We use the phase scrambling bootstrap method to give a nonparametric estimate of the variance of our test statistic under the null hypothesis. Using a simulation study, we demonstrate that the test obtains its target significance level, with large power, when compared to an existing standard parametric test that uses the bispectrum. Further we show how the proposed test can be used to identify the source of nonlinearity due to interactions at specific frequencies. We also investigate implications for heuristic diagnosis of nonstationarity.

Segmenting eukaryotic genomes with the generalized Gibbs sampler

Eukaryotic genomes display segmental patterns of variation in various properties, including GC content and degree of evolutionary conservation. DNA segmentation algorithms are aimed at identifying statistically significant boundaries between such segments. Such algorithms may provide a means of discovering new classes of functional elements in eukaryotic genomes. This paper presents a model and an algorithm for Bayesian DNA segmentation and considers the feasibility of using it to segment whole eukaryotic genomes. The algorithm is tested on a range of simulated and real DNA sequences, and the following conclusions are drawn. Firstly, the algorithm correctly identifies non-segmented sequence, and can thus be used to reject the null hypothesis of uniformity in the property of interest. Secondly, estimates of the number and locations of change-points produced by the algorithm are robust to variations in algorithm parameters and initial starting conditions and correspond to real features in the data. Thirdly, the algorithm is successfully used to segment human chromosome 1 according to GC content, thus demonstrating the feasibility of Bayesian segmentation of eukaryotic genomes. The software described in this paper is available from the author's website (www.uq.edu.au/similar to uqjkeith/) or upon request to the author.

GOVERNANÇA CORPORATIVA E ÍNDICE DE SUSTENTABILIDADE EMPRESARIAL: UMA ANÁLISE DO VALOR DAS AÇÕES

A Governança Corporativa, que surge com uma superação ao conflito de agência, exige dentre seus princípios que as organizações adotem uma estrutura que proteja os direitos dos acionistas e assegure a divulgação e a transparência de fatos relevantes e suas demonstrações contábeis. No Brasil, em 2000, a BM&FBOVESPA criou níveis diferenciados de Governança Corporativa a fim de estimular o interesse de investidores e auxiliar na valorização das empresas que podem aderir voluntariamente a um dos segmentos. Juntamente à preocupação quanto às boas práticas de governança, existe outra questão altamente importante e preocupante que se refere à sustentabilidade. Cada vez mais investidores buscam empresas que atuam sob os princípios do Triple Bottom Line, o qual abrange elementos das esferas ambientais, sociais e econômicas, como uma forma de segurança para seus investimentos. Em 2005, foi criado o Índice de Sustentabilidade Empresarial (ISE), pela BM&FBOVESPA, como uma referência nas boas práticas de sustentabilidade e comprometimento das empresas com a sustentabilidade empresarial. Neste contexto, este estudo visa verificar se existem diferenças entre as médias dos retornos mensais das ações, no período de cinco anos antes e após a sua adesão à Governança Corporativa e ao Índice de Sustentabilidade Empresarial. O método utilizado para testar as hipóteses das três amostras selecionadas foi o Paired-Samples T Test, por meio do software SPSS, versão 18.0. Os resultados obtidos demonstraram que, no caso das amostras do ISE (p= 0,006 < 0,05) e GC_ISE (p= 0,030 < 0,05) a hipótese nula é rejeitada, pois existe diferença significativa entre as médias dos retornos mensais e no caso da amostra de GC (p= 0,081 > 0,05) a hipótese nula não é rejeitada, pois não existe diferença significativa entre estas médias. Analisando os valores das médias é possível perceber que a maioria delas sofre queda no segundo momento de análise, apesar disso não é possível generalizar afirmando que a Governança Corporativa e o Índice de Sustentabilidade Empresarial não agregam valor às empresas e aos acionistas. Isto porque o momento econômico analisado coincide com a crise financeira do subprime, que atingiu as principais bolsas de valores do mundo e influenciou fortemente as ações na BM&FBovespa, principalmente em 2008.

O Conflito de Agência Exposto ao Efeito de Mercado: Um Estudo Empírico de Precificação de Ações da Bombril S/A

Esta dissertação apresenta um estudo exploratório que tem como objetivo a avaliação da reação do mercado frente aos problemas de agência e assimetria informacional entre os acionistas majoritários-controladores e os acionistas minoritários de uma empresa brasileira de capital aberto, no tocante ao valor das suas ações negociadas na Bolsa de Valores de São Paulo. O estudo se propõe a investigar o impacto de precificação dessas ações promovendo a análise do seu comportamento frente à divulgação de notícias de crise e fraude da empresa por meio da mídia especializada. A metodologia adotada consiste na aplicação de estudo de eventos para identificação de retornos anormais da empresa desde a divulgação da primeira notícia selecionada, datada de maio de 2001, até a última notícia em outubro de 2005, utilizando-se de procedimentos estatísticos como a regressão linear e aplicação do teste t de student para estimar e comparar os resultados. Os dados foram obtidos por meio do banco de dados da Economática Ltda, conforme acesso realizado na Universidade de São Paulo. Para objeto de pesquisa foi selecionada a empresa Bombril S/A, por estar em evidências quanto a problemas de agência no âmbito do mercado nacional. Os resultados obtidos apontaram que o mercado reagiu significantemente aos anúncios dos conflitos selecionados, apresentando um valor de p-value <0,05 para os blocos de eventos, o que significa a rejeição da hipótese nula, constatando que a evidencia estatística dos dados testados comprova retornos anormais acumulados diferentes de zero. Entretanto, sugere-se novas pesquisas com outros parâmetros de eventos na busca de mais evidências sobre o efeito das informações no preço das ações.

A verifiable solution to the MEG inverse problem

Magnetoencephalography (MEG) is a non-invasive brain imaging technique with the potential for very high temporal and spatial resolution of neuronal activity. The main stumbling block for the technique has been that the estimation of a neuronal current distribution, based on sensor data outside the head, is an inverse problem with an infinity of possible solutions. Many inversion techniques exist, all using different a-priori assumptions in order to reduce the number of possible solutions. Although all techniques can be thoroughly tested in simulation, implicit in the simulations are the experimenter's own assumptions about realistic brain function. To date, the only way to test the validity of inversions based on real MEG data has been through direct surgical validation, or through comparison with invasive primate data. In this work, we constructed a null hypothesis that the reconstruction of neuronal activity contains no information on the distribution of the cortical grey matter. To test this, we repeatedly compared rotated sections of grey matter with a beamformer estimate of neuronal activity to generate a distribution of mutual information values. The significance of the comparison between the un-rotated anatomical information and the electrical estimate was subsequently assessed against this distribution. We found that there was significant (P < 0.05) anatomical information contained in the beamformer images across a number of frequency bands. Based on the limited data presented here, we can say that the assumptions behind the beamformer algorithm are not unreasonable for the visual-motor task investigated.

Discriminating antigen and non-antigen using proteome dissimilarity:bacterial antigens

It has been postulated that immunogenicity results from the overall dissimilarity of pathogenic proteins versus the host proteome. We have sought to use this concept to discriminate between antigens and non-antigens of bacterial origin. Sets of 100 known antigenic and nonantigenic peptide sequences from bacteria were compared to human and mouse proteomes. Both antigenic and non-antigenic sequences lacked human or mouse homologues. Observed distributions were compared using the non-parametric Mann-Whitney test. The statistical null hypothesis was accepted, indicating that antigen and non-antigens did not differ significantly. Likewise, we were unable to determine a threshold able to separate meaningfully antigen from non-antigen. Thus, antigens cannot be predicted from pathogen genomes based solely on their dissimilarity to the human genome.