Emergence of Hierarchy on a Network of Complementary Agents

Complementarity is one of the main features underlying the interactions in biological and biochemical systems. Inspired by those systems we propose a model for the dynamical evolution of a system composed by agents that interact due to their complementary attributes rather than their similarities. Each agent is represented by a bit-string and has an activity associated to it; the coupling among complementary peers depends on their activity. The connectivity of the system changes in time respecting the constraint of complementarity. We observe the formation of a network of active agents whose stability depends on the rate at which activity diffuses in the system. The model exhibits a non-equilibrium phase transition between the ordered phase, where a stable network is generated, and a disordered phase characterized by the absence of correlation among the agents. The ordered phase exhibits multi-modal distributions of connectivity and activity, indicating a hierarchy of interaction among different populations characterized by different degrees of activity. This model may be used to study the hierarchy observed in social organizations as well as in business and other networks.Comment: 13 pages, 4 figures, submitte

Exploratory research analysis on emissions generated in internal combustion engines

It is common knowledge that internal combustion engines have the function of transforming thermal energy into useful mechanical work. During the combustion process of the fuel and air mixture (heat generation) a quantity of gases are produced and released into the environment by the exhaust system of these engines. When these machines were invented, their creators might not have had the notion that the generated gases would be aggressors to nature. The constant population growth, the increasing demand for the use of these engines and observations of the impact in nature, among them the health and greenhouse effects, evidenced mainly from the end of the last century, led scientists to study the problem related to gaseous emissions from these machines. The present work aims to study and evaluate the emissions of internal combustion engines, their consequences both to the human health and to the environment, the evolution of government legislation and also the control mechanisms implemented to reduce these pollutants. The applied methodology is a qualitative and exploratory study of bibliographic character of theoretical and experimental works that were presented in master's dissertations, doctoral theses, scientific articles and websites of companies specialized in the subject

Aplicação da PCAM e da análise de agrupamento em clones de cupuaçuzeiro.

O objetivo deste trabalho foi estudar a divergência genética de 50 clones de cupuaçuzeiro, por meio da PCAM e da Análise de Agrupament

Avaliação do uso de diferentes tipos de sacos de tecido para incubação in vitro de amostras vegetais.

Resumo: Avaliou-se o potencial de uso de sacos de tecido com diferentes características e porosidades para acondicionamento de amostras em ensaios de produção de gases in vitro. Para isso, amostras de feno de capim coastcross (Cynodon sp.), secas em estufa de ventilação forçada e trituradas (1 mm) foram incubadas durante 96 horas em frascos de vidro com 160 mL de capacidade, contendo 72 mL de meio de cultura e 8 mL de inóculo ruminal. O substrato foi incubado, em quadruplicata, diretamente no frasco de fermentação (controle) ou acondicionado em 3 tipos de saco de tecido: ANKOM filter bag (modelo F57, porosidade = 25 ?m); saco de poliéster (3,5 × 8,0 cm) com porosidade de 25 ?m; saco de poliéster (3,5 × 8,0 cm) com porosidade de 40 ?m. Os valores de degradabilidade da matéria seca não diferiram entre os tratamentos após 96 horas de incubação (P>0,05). A produção acumulada de gases, no entanto, foi 12% inferior ao controle quando o substrato foi incubado em saco de poliéster com porosidade de 40 ?m (P0.05). Total gas production, however, was 12% lower for the substrate incubated in 40-?m polyester bags in comparison to the control (P<0.05). Enclosing samples in cloth bags altered the fermentation kinetic of the incubated substrate, mainly in regard to the rate of gas production (P<0.05). Such alterations were significantly greater when using ANKOM F57 filter bags (P<0.05). Enclosing samples in cloth bags is not appropriate to estimate fermentation kinetic parameters by using the gas production technique

A genetic toolkit and gene switches to limit Mycoplasma growth for biosafety applications

Mycoplasmas have exceptionally streamlined genomes and are strongly adapted to their many hosts, which provide them with essential nutrients. Owing to their relative genomic simplicity, Mycoplasmas have been used to develop chassis for biotechnological applications. However, the dearth of robust and precise toolkits for genomic manipulation and tight regulation has hindered any substantial advance. Herein we describe the construction of a robust genetic toolkit for M. pneumoniae, and its successful deployment to engineer synthetic gene switches that control and limit Mycoplasma growth, for biosafety containment applications. We found these synthetic gene circuits to be stable and robust in the long-term, in the context of a minimal cell. With this work, we lay a foundation to develop viable and robust biosafety systems to exploit a synthetic Mycoplasma chassis for live attenuated vectors for therapeutic applications

Predição da massa corporal em pequenos ruminantes por meio de medidas morfométricas.

A determinação da massa corporal é importante para o melhoramento genético e para os manejos nutricional, reprodutivo e sanitário. Todavia, a inexistência de balanças em grande parte das propriedades rurais dificulta a coleta dessa informação. Assim, esse estudo teve como objetivo determinar a relação entre medidas morfométricas e a massa corporal para servir de base para o desenvolvimento de uma ferramenta de estimativa da massa baseada em mensurações corporais

Diversificação de cultivares de citros nos Tabuleiros Costeiros.

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