Unique and conserved functions of B cell-activating factor of the TNF family (BAFF) in the chicken.

The chicken represents the best-characterized animal model for B cell development in the so-called gut-associated lymphoid tissue (GALT) and the molecular processes leading to B cell receptor diversification in this species are well investigated. However, the mechanisms regulating B cell development and homeostasis in GALT species are largely unknown. Here we investigate the role played by the avian homologue of B cell-activating factor of the tumor necrosis factor family (BAFF). Flow cytometric analysis showed that the receptor for chicken B cell-activating factor of the tumor necrosis factor family (chBAFF) is expressed by mature and immature B cells. Unlike murine and human BAFF, chBAFF is primarily produced by B cells both in peripheral lymphoid organs and in the bursa of Fabricius, the chicken's unique primary lymphoid organ. In vitro and in vivo studies revealed that chBAFF is required for mature B cell survival. In addition, in vivo neutralization with a decoy receptor led to a reduction of the size and number of B cell follicles in the bursa, demonstrating that, in contrast to humans and mice, in chickens BAFF is also required for the development of immature B cells. Collectively, we show that chBAFF has phylogenetically conserved functions in mature B cell homeostasis but displays unique and thus far unknown properties in the regulation of B cell development in birds.

Reproduction and fertility life table of three aphid species (Macrosiphini) at different temperatures

Temperature is a key abiotic factor influencing the development and reproduction of aphids. The effect of temperature on the reproduction of three aphid species Aulacorthum solani (Kaltenbach), Macrosiphum euphorbiae (Thomas) and Uroleucon ambrosiae (Thomas) (Aphididae, Macrosiphini) has been investigated and fertility life tables were determined. Nymphs were reared in climatic chambers at temperatures of 16, 19, 22, 25, and 28 ± 1ºC, RH 70 ± 10% and 12 h photophase. Female adult aphids developed at these temperatures were then used in experiments in which pre-reproductive and reproductive periods were evaluated every 24 h. In addition, the number of nymphs produced and longevity were determined at each temperature. The reproduction period of A. solani and M. euphorbiae decreased with increasing temperature, whereas that of U. ambrosiae was maintained between 19 and 25ºC. The total number of nymphs produced by the aphids decreased as the temperature increased. The longevities of A. solani and M. euphorbiae decreased with increasing temperature but remained stable for U. ambrosiae between 19 and 25ºC. The largest survival rate (l x) and specific fertility (m x) values were found at 16 and 22ºC for all three species. The most favourable temperature for reproduction of A. solani, M. euphorbiae and U. ambrosiae was 22ºC, as demonstrated by the l x and m x profiles, the high values of net reproductive rates and intrinsic rates of increase, and the short intervals between generation and doubling times.

Macrophages promote epithelial repair through hepatocyte growth factor secretion.

Macrophages play a critical role in intestinal wound repair. However, the mechanisms of macrophage-assisted wound repair remain poorly understood. We aimed to characterize more clearly the repair activities of murine and human macrophages. Murine macrophages were differentiated from bone marrow cells and human macrophages from monocytes isolated from peripheral blood mononuclear cells of healthy donors (HD) or Crohn's disease (CD) patients or isolated from the intestinal mucosa of HD. In-vitro models were used to study the repair activities of macrophages. We found that murine and human macrophages were both able to promote epithelial repair in vitro. This function was mainly cell contact-independent and relied upon the production of soluble factors such as the hepatocyte growth factor (HGF). Indeed, HGF-silenced macrophages were less capable of promoting epithelial repair than control macrophages. Remarkably, macrophages from CD patients produced less HGF than their HD counterparts (HGF level: 84âeuro0/00±âeuro0/0027âeuro0/00pg/mg of protein and 45âeuro0/00±âeuro0/0034âeuro0/00pg/mg of protein, respectively, for HD and CD macrophages, Pâeuro0/00<âeuro0/000·009) and were deficient in promoting epithelial repair (repairing activity: 90·1âeuro0/00±âeuro0/004·6 and 75·8âeuro0/00±âeuro0/008·3, respectively, for HD and CD macrophages, Pâeuro0/00<âeuro0/000·0005). In conclusion, we provide evidence that macrophages act on wounded epithelial cells to promote epithelial repair through the secretion of HGF. The deficiency of CD macrophages to secrete HGF and to promote epithelial repair might contribute to the impaired intestinal mucosal healing in CD patients.

Effects of sex, host-plant deprivation and presence of conspecific immatures on the cannibalistic behavior of wild Ascia monuste orseis (Godart) (Lepidoptera, Pieridae)

Effects of sex, host-plant deprivation and presence of conspecific immatures on the cannibalistic behavior of wild Ascia monuste orseis (Godart) (Lepidoptera, Pieridae). The specialist cabbage caterpillar Ascia monuste orseis (Lepidoptera, Pieridae) feeds on plants of the Brassicaceae family, but may eventually ingest conspecific eggs and larvae during the larval stage. The present study examines feeding behavior of 4th and 5th instar cabbage caterpillars in relation to sex, host-plant deprivation and presence of conspecifics. We recorded number of egg ingested per larvae, developmental indices and duration of feeding, exploratory and resting behavior. Kale deprived caterpillars presented high rates of cannibalism, development delay and decreased fecundity. Cannibalism rates were not influenced by the sex of the larvae. In general, the presence of conspecific eggs did not interfere with the frequency and duration of the categorical behavioral events. We conclude that food availability is a strong factor influencing the extent to which A. monuste orseis caterpillars cannibalize.

Turismo Rural como factor de desenvolvimento para São Tomé: Proposta das actividades turísticas para Roça de Monte Café e Suas Dependências

O trabalho agora concluído pretende apresentar uma proposta de desenvolvimento do turismo rural para São Tomé. Baseado na análise de estudo de caso de outros países, com objectivo de propor actividades turísticas envolvendo a comunidade local e os representantes do turismo, o estudo tenciona contribuir para a construção de uma imagem positiva da roça de Monte Café e suas dependências, visando o seu desenvolvimento. A referida Roça, enquanto um património arquitectónico, histórico, cultural, agroeconómico e natural, oferece as condições necessárias para a prática de turismo, relacionadas com a aventura, o espaço rural e a ecologia. Tais aspectos, aliados a uma infra-estrutura e a um planeamento adequado, tornam-se um excelente produto turístico. Com aplicação do inquérito por questionário para os residentes, comprova-se a possibilidade de implementação do projecto do ponto de vista social, desde que seja planeado de forma a prever impactos negativos e positivos futuros, e garantir um turismo sustentável.

Variaciones en el factor de condición, coeficiente alimentario y alimentación de la Sardina Peruana (Sardinops sagax sagax) durante el período 1975-1986

En un total de 28,265 individuos de Sardina se estudiaron el factor de condición, el coeficiente alimentario y los ítems alimentarios entre 1975 y 1986. Los cambios observados comparados a la situación “normal” en 1980. Durante El Niño 1976-77 la sardina ingirió más fitoplancton que zooplancton, aumentando el coeficiente alimentario pero decreciendo el factor condición.

Increasing returns, imperfect competition and factor prices

We show how, in general equilibrium models featuring increasing returns, imperfectcompetition and endogenous markups, changes in the scale of economic activity affectincome distribution across factors. Whenever final goods are gross-substitutes (gross-complements), a scale expansion raises (lowers) the relative reward of the scarce factoror the factor used intensively in the sector characterized by a higher degree of product differentiation and higher fixed costs. Under very reasonable hypothesis, our theory suggests that scale is skill-biased. This result provides a microfoundation for the secular increase in the relative demand for skilled labor. Moreover, it constitutes an important link among major explanations for the rise in wage inequality: skill-biased technical change, capital-skill complementarities and international trade. We provide new evidence on the mechanism underlying the skill bias of scale.

O planeamento estratégico como factor de suceso das empresas

A presente monografia aborda o tema do planeamento estratégico como fator de sucesso das empresas, enquanto instrumento de avaliação da situação das empresas em São Vicente, e tem como objetivo “demonstrar a importância do planeamento para as empresas”. Para a sua elaboração utilizou-se a amostra pelo método não probabilistico, ou seja, o de amostra por conveniência e optou-se por uma abordagem quantitativa pela técnica de recolha de dados através da aplicação de questionários dirigidos às empresas atuantes na ilha de São Vicente. Dadas as incertezas do mundo atual, a sobrevivência e o desenvolvimento das empresas dependem, cada vez mais, da sua capacidade de definição de uma estratégia coerente, potencializando oportunidades e ultrapassando obstáculos. No percurso da investigação tentaremos responder à seguinte pergunta: “Poderá o Planeamento Estratégico ser considerado uma ferramenta de competitividade e sucesso das empresas?” Esta monografia e sua fundamentação teórica têm por finalidade demonstrar os procedimentos do Planeamento estratégico nas diversas áreas das empresas e avaliar a adoção desta ferramenta como incremento de competitividade à medida que a utilização desta proporciona reflexões e diretrizes para as atividades da organização, como também possibilita a adaptação e capacidade de resposta às mudanças do mercado.

A two-mean reverting-factor model of the term structure of interest rates

This paper presents a two--factor model of the term structure ofinterest rates. We assume that default free discount bond prices aredetermined by the time to maturity and two factors, the long--term interestrate and the spread (difference between the long--term rate and theshort--term (instantaneous) riskless rate). Assuming that both factorsfollow a joint Ornstein--Uhlenbeck process, a general bond pricing equationis derived. We obtain a closed--form expression for bond prices andexamine its implications for the term structure of interest rates. We alsoderive a closed--form solution for interest rate derivatives prices. Thisexpression is applied to price European options on discount bonds andmore complex types of options. Finally, empirical evidence of the model'sperformance is presented.

Calcifications vasculaires et déficit en vitamine K: un facteur de risque modifiable dans l'insuffisance rénale chronique [Vascular calcifications and vitamin K deficiency: a modifiable risk factor in chronic kidney disease].

The mechanisms of vascular calcifications in chronic renal failure are complex. Apart for clotting factors, vitamin K-dependent proteins include matrix Gla protein. Glutamic acid residues in matrix Gla protein are carboxylated by vitamin K-dependent gamma-carboxylase, which enables it to inhibit calcification. The purpose of this review is to discuss available evidence implicating vitamin K as a modifiable risk factor in the pathogenesis of vascular calcification in renal diseases.

A Gestão de Stock: O Fornecimento de OutPut como factor de redução de custo

O presente trabalho tem como objectivo mostrar a importância que a Gestão económica de Stock tem no processo de redução de custo, por via da implementação de um modelo. E para isso far-se-á um estudo de caso numa empresa inserida no ramo de transformação de pescado – FRESCOMAR. A metodologia adoptada para alcançar os objectivos propostos passou pela pesquisa bibliográfica, recolha de dados e de informação relevante junto da empresa e tratamento dos dados numa folha de Excel. O modelo de gestão de Stock a ser implementado depende essencialmente da componente procura, onde que para uma empresa com procura constante utiliza-se os modelos determinísticos e para uma com procura aleatória utiliza-se os modelos estocásticos (Nível de Encomenda e Revisão Cíclica). Nos modelos determinísticos temos 4 modelos diferenciados pela forma de reposição e a admissibilidade da procura. Com as informações recolhidas junto da empresa em estudo escolhemos implementar o modelo de reposição não instantânea com ruptura não permitida e obtivemos a optimização do Stock com níveis reduzidos de produção e consequentemente houve uma diminuição do custo. Com resultados obtiveram-se ainda valores da Quantidade Óptima a ser Produzida, do Stock Máximo e do Custo Total Óptimo por unidade de tempo. Devido a diversidade de produtos propomos à empresa a utilização da análise ABC para classificar os produtos reagrupando-os em classes A, B e C, conforme o peso no consumo de Stock.

Leaf-litter amount as a factor in the structure of a ponerine ants community (Hymenoptera, Formicidae, Ponerinae) in an eastern Amazonian rainforest, Brazil

Leaf-litter amount as a factor in the structure of a ponerine ants community (Hymenoptera, Formicidae, Ponerinae) in an eastern Amazonian rainforest, Brazil. Leaf-litter may be an important factor in structuring ponerine ant communities (Hymenoptera, Formicidae, Ponerinae) in tropical rainforests. We specifically examined how leaf-litter affects the structure of a ponerine ant community in primary Amazonian rainforest sites at the Ferreira Penna Scientific Station, Pará, Brazil. A total of 53 species belonging to eight genera of three ponerine tribes were collected with mini-Winkler extractors. The amount of leaf-litter positively affected the abundance and richness of the ponerine ant community, and also influenced species composition. Nearby samples often had low species similarity, especially when adjacent samples differed in the amount of leaf-litter. Leaf-litter availability in Amazonian primary forests is a key factor for distribution of ground-dwelling ponerine species, even at small scales.

The social value of health programs: Is age a relevant factor?

In cost-effectiveness analysis (CEA) it is usually assumed that a QALY is of equal value to everybody, irrespective of the patient's age. However, it is possible that society assigns different social values to a QALY according to who gets it. In this paper we discuss the possibility of weighting health benefits for age in CEA. We also examinethe possibility that age-related preferences depend on the size of the health gain. An experiment was performedto test these hypotheses. The results assessing suggest that the patient's age is a relevant factor when assessing health gains.

A liderança como factor de sucesso empresarial O caso da empresa Anjos Mundilar

O desempenho da empresa é influenciado pelas competências dos seus funcionários. A competência humana aliada a outros recursos empresariais dá origem e sustentação à competência empresarial. A participação dos funcionários no processo de gestão de competências expondo as suas expectativas, motivações e também, percepções a respeito do seu superior e da estratégia de negócios da empresa é fundamental para o sucesso empresarial.