Chemical defense of Hymeniacidon heliophila (Porifera: halichondrida) against tropical predators

Diversos organismos bênticos possuem defesas químicas que ajudam a diminuir a predação. Embora sua eficácia seja comprovada, muitos de seus efeitos são ainda desconhecidos. Múltiplas funções dos metabolitos secundários foram evidenciadas em algumas esponjas e isso pode representar uma vantagem adaptativa, considerando o alto valor energético gasto pelas espécies para produzí-los. O objetivo desse trabalho foi investigar as propriedades defensivas de extratos da esponja Hymeniacidon heliophila contra predadores tropicais: paguros (Calcinus tibicens), ouriços-do-mar (Lytechinus variegatus) e peixes generalistas. Extratos em n-hexano, acetato de etila e acetona/metanol foram usados nos ensaios e todos foram eficientes na redução do consumo por C. tibicen; extratos em n-hexano reduziram o consumo por L. variegatus; e extratos de média polaridade reduziram o consumo por peixes. A variação na ação ou as funções ecológicas múltiplas dos extratos indicam que diferentes tipos de substâncias podem ser associadas ao sistema defensivo produzido por Hymeniacidon heliophila.Various benthic organisms have chemical defenses which reduce their predators' consumption. Although their efficiency may be noticed in many organisms, many of their effects are not well- known yet. Multiple ecological roles of secondary metabolites are shown in some sponges, which may represent an adaptative advantage considering the high amount of energy used to produce these chemical compounds. The goal of this work was to investigate the defensive property of the extracts from the sponge Hymeniacidon heliophila against the tropical predators: hermit crabs (Calcinus tibicens), sea urchins (Lytechinus variegatus) and generalist fishes. Extracts obtained with n-hexane, ethyl acetate and acetone/methanol were used in assays and all of them were effective in reducing the consumption by C. tibicens; n-hexane extract reduced the consumption by L. variegatus; and medium polarity extracts reduced fish consumption. Either the variation in action or the multiple ecological roles of the extracts indicates that different types of compounds can be associated to the defensive system produced by H. heliophila

Perilipin regulates the thermogenic actions of norepinephrine in brown adipose tissue

In response to cold, norepinephrine (NE)-induced triacylglycerol hydrolysis (lipolysis) in adipocytes of brown adipose tissue (BAT) provides fatty acid substrates to mitochondria for heat generation (adaptive thermogenesis). NE-induced lipolysis is mediated by protein kinase A (PKA)-dependent phosphorylation of perilipin, a lipid droplet-associated protein that is the major regulator of lipolysis. We investigated the role of perilipin PKA phosphorylation in BAT NE-stimulated thermogenesis using a novel mouse model in which a mutant form of perilipin, lacking all six PKA phosphorylation sites, is expressed in adipocytes of perilipin knockout (Peri KO) mice. Here, we show that despite a normal mitochondrial respiratory capacity, NE-induced lipolysis is abrogated in the interscapular brown adipose tissue (IBAT) of these mice. This lipolytic constraint is accompanied by a dramatic blunting (∼70%) of the in vivo thermal response to NE. Thus, in the presence of perilipin, PKA-mediated perilipin phosphorylation is essential for NE-dependent lipolysis and full adaptive thermogenesis in BAT. In IBAT of Peri KO mice, increased basal lipolysis attributable to the absence of perilipin is sufficient to support a rapid NE-stimulated temperature increase (∼3.0°C) comparable to that in wild-type mice. This observation suggests that one or more NE-dependent mechanism downstream of perilipin phosphorylation is required to initiate and/or sustain the IBAT thermal response

Predicting the distribution of canine leishmaniasis in western Europe based on environmental variables.

The domestic dog is the reservoir host of Leishmania infantum, the causative agent of zoonotic visceral leishmaniasis endemic in Mediterranean Europe. Targeted control requires predictive risk maps of canine leishmaniasis (CanL), which are now explored. We databased 2187 published and unpublished surveys of CanL in southern Europe. A total of 947 western surveys met inclusion criteria for analysis, including serological identification of infection (504, 369 dogs tested 1971-2006). Seroprevalence was 23 2% overall (median 10%). Logistic regression models within a GIS framework identified the main environmental predictors of CanL seroprevalence in Portugal, Spain, France and Italy, or in France alone. A 10-fold cross-validation approach determined model capacity to predict point-values of seroprevalence and the correct seroprevalence class (20%). Both the four-country and France-only models performed reasonably well for predicting correctly the 20% seroprevalence classes (AUC >0 70). However, the France-only model performed much better for France than the four-country model. The four-country model adequately predicted regions of CanL emergence in northern Italy (<5% seroprevalence). Both models poorly predicted intermediate point seroprevalences (5-20%) within regional foci, because surveys were biased towards known rural foci and Mediterranean bioclimates. Our recommendations for standardizing surveys would permit higher-resolution risk mapping

A mixed-method approach for the assessment of local community perception towards wind farms

The implementation of wind power projects can have significant impacts on local communities. If on one hand the project can bring important economic benefits, on the other hand it can represent a source of conflicts and discontentment. This paper aims to revisit this topic, addressing impacts and their perceptions from the local community point of view. A mixed method approach was proposed and implemented in a Portuguese region (municipality) used as case study. Semi-structured interviews directed towards local stakeholders were conducted to evaluate the acceptance of these wind power projects and the perceived impacts. The qualitative study was subsequently complemented and validated by a quantitative approach, through a questionnaire targeting local population. In general, the collected opinions seem mainly driven by the perceived socio-economic benefits resulting from wind farm deployment, with generally positive attitude towards wind farms. Identified local positive impacts include "community funds", "benefits in kind" and "indirect local employment". The key role of benefit sharing mechanisms on ensuring public acceptance and effective local development is confirmed.- This work has been supported by FCT - Fundacao para a Ciencia e Tecnologia (Portugal) within the Project Scope: UID/CEC/00319/2019

Comportamento e estrutura a termo da volatilidade de empresas de grande e pequeno porte

Em contraposição às hipóteses para sustentação dos modelos financeiros "clássicos", como o Capital Asset Pricing Model (CAPM) de Sharpe-Litner-Mossin, a literatura recente de Finanças tem documentado que algumas características das empresas se mostram relevantes para explicar retornos esperados. Este artigo tem por objetivo analisar se o tamanho da empresa no Brasil é uma característica importante para explicar uma outra dimensão da relação risco versus retorno: a volatilidade. Como metodologia, procedeu-se a uma reestruturação completa do índice IBrX da Bolsa de Valores de São Paulo (Bovespa), obtendo-se dois novos índices: um de empresas com grande porte e outro de empresas com pequeno porte. A partir dos índices construídos, analisaram-se o comportamento e a estrutura a termo da volatilidade, com ajustes dos modelos GARCH (1,1) e TARCH (1,1). Em linhas gerais, pode-se concluir que o comportamento e a estrutura a termo da volatilidade de empresas de grande e pequeno porte são diferentes, o que permite a incorporação da característica tamanho da empresa nas funções financeiras, tais como decisões de investimentos, precificação de títulos e gerenciamento de risco.Recent finance literature states that certain company characteristics are relevant to explain the returns expected, which is contrary to classic financial models such as the Capital Asset Pricing Model. The effect of company size in Brazil was investigated to verify if it explains another aspect of the relationship of risk versus return, which is volatility. The method used was to restructure the IBrX index (Sao Paulo Stock Exchange - Bovespa) to obtain a new index for large sized companies and also another for small companies. The behavior and term structure of volatility was analyzed using adjustments of the GARCH (1.1) and TARCH (1.1) models for each of the two new indices. It was concluded that, in general, small and large companies have different behaviors and term structures of volatility. Therefore, this size aspect should be taken into account for decisions, instrument pricing and risk management in financial considerations

Comparações múltiplas das carteiras de bolsa no Brasil: avaliação da performance do Índice de Governança Corporativa

The adoption of higher corporate governance standards increases the return, reduces the volatility of returns while enhancing the volume negotiated and the liquidity, exposure of stock returns to external risks is also reduced which lowers the cost of capital and increases the value of the company. These theories are analyzed for the Brazilian market with a review of literature for the purpose of studying portfolios to evaluate the performance of the Corporate Governance Index (CGI). The Bootstrap re-sampling method was used to compare mean and medians of the CGI, Ibovespa (IBO), IBrX, IBrX-50, FGV-E e FGV-100 portfolios from July 2001 to August 2005 for three different indicators which were returns, risks and returns adjusted for risk. For the first indicator both the nominal and real returns were used. In the second case risk measures for monthly nominal returns were used: the standard deviation, coefficient of variation and Beta of CAPM. Finally for returns adjusted for risk, the Sharpe Index (S), Treynor Index (T), M² Index, Alfa of Jensen ( &#945; ) and Appraisal Ratio (A) were adopted. In view of the small statistical differences found it was concluded that the CGI performance was good therefore corroborating the value of higher corporate governance practices.A adoção de padrões de governança corporativa superiores aumenta o retorno, reduz a volatilidade dos retornos, aumenta o volume negociado e a liquidez, e diminui a exposição dos retornos das ações a riscos externos, o que conseqüentemente torna o custo de capital menor e eleva o valor da empresa. Este artigo tem por objetivo geral analisar essas hipóteses no mercado de capitais nacional mediante a revisão da literatura existente, e como objetivo específico desenvolver um Estudo de Carteiras para avaliar a performance do Índice de Governança Corporativa (IGC). Nesse sentido, por meio do método de reamostragem Bootstrap, comparam-se as médias e medianas das carteiras: IGC, Ibovespa (IBO), IBrX, IBrX-50, FGV-E e FGV-100, no período de julho de 2001 a agosto de 2005, em três diferentes classes de indicadores: retornos, risco e retornos ajustados ao risco. Na primeira classe de indicadores foram utilizados os retornos nominais e reais e na segunda foram empregadas as medidas de risco dos retornos nominais mensais: desvio-padrão, coeficiente de variação e Beta do CAPM. Relativamente aos retornos ajustados ao risco, usaram-se os seguintes indicadores: Índice de Sharpe (S), Índice de Treynor (T), Índice M², Alfa de Jensen ( &#945; ) e Appraisal Ratio (A). Conclui-se que, apesar de poucas diferenças estatísticas, o IGC apresentou uma boa performance, corroborando a eficácia de melhores práticas de governança corporativa

Mensuração da rentabilidade do crédito comercial: aplicação em um caso atacadista-distribuidor

Credit extension evaluation is traditionally marked by customer’s credit risk and his business potential, normally, the profitability that limit utilization may provide the company is not considered. Therefore, the purpose of this paper is to present a trade credit extension profitability measurement model. The literature used for the theoretical basis involves the profitability concept of the Theory of Restrictions (TOC) and the performance measure calculation as in RAROC model. Proposed model was applied in a wholesaler-distributor company and its results have enabled concluding that credit extension to customers rated as low risk is not always the most profitable option. The decision of companies that only take into consideration credit risk and customer size to set the credit limit may entail incorrect decisions that are decreasing the company’s gain instead of increasing the wealth of its owners.A avaliação para concessão de crédito é tradicionalmente balizada pelo risco de crédito do cliente e seu potencial de negócios, normalmente, não se considera a rentabilidade que a utilização do limite pode proporcionar à empresa. Assim, o objetivo deste trabalho é apresentar um modelo de mensuração da rentabilidade da concessão do crédito comercial. A literatura usada para o embasamento teórico envolve o conceito de rentabilidade da Teoria das Restrições (TOC) e o cálculo da medida de desempenho como no modelo RAROC. O modelo proposto foi aplicado em uma empresa atacadista-distribuidor e os seus resultados possibilitaram concluir que a concessão de crédito para clientes classificados como de baixo risco nem sempre é a opção mais rentável. A decisão das empresas que levam em consideração apenas o risco de crédito e o porte do cliente para estipulação do limite de crédito pode ocasionar decisões incorretas que estejam diminuindo o ganho da empresa ao invés de aumentando a riqueza de seus proprietários