Recording from two neurons: second order stimulus reconstruction from spike trains and population coding

We study the reconstruction of visual stimuli from spike trains, recording simultaneously from the two H1 neurons located in the lobula plate of the fly Chrysomya megacephala. The fly views two types of stimuli, corresponding to rotational and translational displacements. If the reconstructed stimulus is to be represented by a Volterra series and correlations between spikes are to be taken into account, first order expansions are insufficient and we have to go to second order, at least. In this case higher order correlation functions have to be manipulated, whose size may become prohibitively large. We therefore develop a Gaussian-like representation for fourth order correlation functions, which works exceedingly well in the case of the fly. The reconstructions using this Gaussian-like representation are very similar to the reconstructions using the experimental correlation functions. The overall contribution to rotational stimulus reconstruction of the second order kernels - measured by a chi-squared averaged over the whole experiment - is only about 8% of the first order contribution. Yet if we introduce an instant-dependent chi-square to measure the contribution of second order kernels at special events, we observe an up to 100% improvement. As may be expected, for translational stimuli the reconstructions are rather poor. The Gaussian-like representation could be a valuable aid in population coding with large number of neurons

Risk Premium: Insights Over The Threshold

The aim of this paper is twofold: First to test the adequacy of Pareto distributions to describe the tail of financial returns in emerging and developed markets, and second to study the possible correlation between stock market indices observed returns and return’s extreme distributional characteristics measured by Value at Risk and Expected Shortfall. We test the empirical model using daily data from 41 countries, in the period from 1995 to 2005. The findings support the adequacy of Pareto distributions and the use of a log linear regression estimation of their parameters, as an alternative for the usually employed Hill’s estimator. We also report a significant relationship between extreme distributional characteristics and observed returns, especially for developed countries.

RISK PREMIUM: INSIGHTS OVER THE THRESHOLD

The aim of this paper is twofold: First to test the adequacy of Pareto distributions to describe the tail of financial returns in emerging and developed markets, and second to study the possible correlation between stock market indices observed returns and return’s extreme distributional characteristics measured by Value at Risk and Expected Shortfall. We test the empirical model using daily data from 41 countries, in the period from 1995 to 2005. The findings support the adequacy of Pareto distributions and the use of a log linear regression estimation of their parameters, as an alternative for the usually employed Hill’s estimator. We also report a significant relationship between extreme distributional characteristics and observed returns, especially for developed countries.

Risk premium: insights over the threshold

The aim of this paper is twofold: First to test the adequacy of Pareto distributions to describe the tail of financial returns in emerging and developed markets, and second to study the possible correlation between stock market indices observed returns and return's extreme distributional characteristics measured by Value at Risk and Expected Shortfall. We test the empirical model using daily data from 41 countries, in the period from 1995 to 2005. The findings support the adequacy of Pareto distributions and the use of a log linear regression estimation of their parameters, as an alternative for the usually employed Hill's estimator. We also report a significant relationship between extreme distributional characteristics and observed returns, especially for developed countries

Myopic Loss Aversion and House-Money Effect Overseas: an experimental approach

Recent literature has found two behavioral effects - house-money and myopic loss aversion (MLA) - in several experimental designs. We show that although we can find a house-money effect using survey methods this evidence disappears when we study investment decision within a multi-period investment experiment. Loss aversion is found to govern the risk-taking behavior of subjects in dynamic settings, overcoming the house-money effect. These results are robust to experiments conducted in two different countries, Spain and Brazil.

Variação da produtividade do arroz de terras altas influenciados pela seca meteorológica em Goiás.

A seca é um fenômeno meteorológico caracterizado pela falta de precipitação pluvial, que pode causar grandes prejuízos à produção agrícola. O presente trabalho tem como objetivo caracterizar a ocorrência de seca, utilizando o Índice Padronizado de Precipitação (SPI) em cinco microrregiões do estado de Goiás e sua influencia na produtividade de arroz de terras altas. As cinco microrregiões estudadas foram: Anápolis, Ceres, Iporá, Anicuns e Goiânia. A série de dados históricos de precipitação foi disponibilizada pela Agência Nacional de Águas (ANA), coletados em um município pertencente à microrregião analisada. O período de estudo foi de 1975 a 2005. Os dados de produtividade, para o mesmo período foi disponibilizado pela AGROTEC. Os valores do SPI foram caracterizados pela a ocorrência dos eventos de seca, frequência relativa, comparação com os dados de produtividade do arroz de terras altas e o percentual de acerto do índice. Foi possível observar que o SPI não acompanhou totalmente a variação da produtividade do arroz de terras altas. O SPI apresentou percentuais de acerto baixos, em todas as microrregiões, ficando próximo a 51%

Análise de solos: finalidade e procedimentos de amostragem.

A análise de solos é o único método que permite, antes do plantio, conhecer a capacidade de um determinado solo suprir nutrientes para as plantas. É a forma mais simples, econômica e eficiente de diagnose da fertilidade das terras e constitui base imprescindível para a recomendação de quantidades adequadas de corretivos e fertilizantes para aumentar a produtividade das culturas e, como consequência a produção e a lucratividade das lavouras.bitstream/CPAP-2010/57309/1/COT79.pd

Soil carbon and nitrogen stocks under natural forested savannah and cultivated pasture in the Pantanal, Mato Grosso do Sul, Brazil.

The goal of this study was to estimate the soil C and N stocks under Urochloa spp.pasture with a natural forested savannah as a reference.(Embrapa Gado de Corte. Documentos, 216). Coordenador Roberto Giolo de Almeida. II SIGEE. Disponível em: . Acesso em: 30 nov. 2016

Digital tourism marketing: Case study of the campaign Can’t Skip Portugal

The theme of this study is the analysis of the advertising campaign "Can’t Skip Portugal" launched in 2017 by Tourism of Portugal, which the main objective was to show all the regions of the country, covering not only the most known areas but also to promote other areas of the country, showcasing Portugal as a potential destination for tourists. The objective of the study is to understand how this kind of Digital Marketing can be sufficiently appealing and arouse in-terest in the viewers. To reach the proposed objective, a qualitative research of descriptive type was carried out. Throughout this study it was possible to have a better understanding of the benefits of Digital Marketing. It could be con-cluded that the advertising campaign “Can’t Skip Portugal” achieved its pro-posed goals, involving and influencing the target audience in the choice of Portugal as a touristic destination.info:eu-repo/semantics/acceptedVersio