Correlation effects in a simple model of small-world network

We analyze the effect of correlations in a simple model of small world network by obtaining exact analytical expressions for the distribution of shortest paths in the network. We enter correlations into a simple model with a distinguished site, by taking the random connections to this site from an Ising distribution. Our method shows how the transfer matrix technique can be used in the new context of small world networks.Comment: 10 pages, 3 figure

Control strategies for intermittently mixed, forcefully aerated solid-state fermentation bioreactors based on the analysis of a distributed parameter model

Fernandez-Fernandez, M. Departamento de Ciencias de la Ingeniería,Universidad de Talca,Camino a Los Niches Km.1,Curicó,ChileThis paper tests different control strategies based on classic proportional integral derivative (PID) and advanced dynamic matrix control (DMC) algorithms for an intermittently stirred, forcefully aerated solid-state fermentation bioreactor. The study was done using a distributed parameter model to reproduce the main operating features of this type of bioreactor. There is predicted to be a remarkable improvement in the bioreactor productivity when control strategies are implemented. For this type of bioreactor, the temperature and water content of the substrate bed can be controlled by saturating the air at the air inlet but manipulating its temperature, coupled with a strategy of water replenishment when the water content of the bed falls below a threshold. Dynamic matrix control is superior to PID control; however, a specific convolution matrix for different stages of the fermentation is necessary due to the changing behavior of the system. This work shows the benefit of mathematical modeling, since the many different operating conditions investigated via simulations would not have been economically feasible to undertake experimentally with a large-scale bioreactor. The results obtained provide an excellent starting point for such large-scale experimental work

Avaliação dos benefícios da coleta de lixo em Palmas, Tocantins: uma aplicação do método de avaliação contingente Evaluation of the garbage collection benefits in Palmas, Tocantins: an application of contingent evaluation method

O acesso aos serviços de saneamento ambiental, em especial, a coleta e a disposição final dos resíduos sólidos, é fundamental para a saúde pública e a preservação do meio ambiente, pois com a redução da má disposição do lixo, ocorre uma diminuição das endemias e da contaminação do solo. O investimento em saneamento ambiental é um dos grandes desafios para os gestores públicos, devido a sua ampla relação entre meio ambiente, saúde pública e desenvolvimento local. O presente trabalho visou estimar a máxima disposição a pagar pelo serviço de coleta de lixo para o município de Palmas, em Tocantins, por meio do método de avaliação contingente. Os resultados obtidos indicam que os principais fatores determinantes da disposição a pagar são: o nível de renda e a escolaridade.<br>The access to environmental sanitation services, especially the collection and final disposition of solid residues, is fundamental for the public health and environment preservation, because by reducing the bad garbage disposition, there is a decrease of the endemic diseases and soil contamination. The investment in environmental sanitation is one of the great challenges for public managers, due to its wide relationship among the environment, public health, and local development. The present work sought to esteem the willingness to pay for the garbage collection service for the municipal district of Palmas, in Tocantins, through the contingent evaluation method. The obtained results indicate that the main decisive factors of the willingness to pay are: the level of income and the education

Produção leiteira, composição do leite e perfil bioquímico sanguíneo de vacas lactantes sob suplementação com sal aniônico Milk yield, milk composition and biochemical blood profile of lactating cows supplemented with anionic salt

Objetivou-se avaliar os efeitos da inclusão de sal aniônico na dieta sobre as características físicas e a composição química do leite, o perfil bioquímico sanguíneo, a produção de leite, o peso e a condição corporal de vacas em lactação. Foram utilizadas 20 vacas da raça Jersey distribuídas em duas dietas, uma sem adição de sal aniônico e outra com adição de 0,25 kg/dia de cloreto de amônio. O delineamento empregado foi o completamente casualizado. As vacas sob suplementação com sal aniônico apresentaram menor pH urinário e aumento das concentrações sanguíneas de ureia, cálcio e magnésio. Com a dieta aniônica, o leite precipitou com menores concentrações de etanol, apresentou menor densidade, porcentagens de lactose, proteína e imunoglobulina, porém maior teor de cálcio iônico. O fornecimento de dieta aniônica durante a lactação resultou em acidose metabólica, o que alterou o perfil bioquímico sanguíneo e as características físico-químicas do leite.<br>The objective of this work was to evaluate the inclusion of anionic salt in the diet on the physical characteristics and chemical composition of milk, biochemical blood profile, milk yield, body weight and condition. It was used 20 Jersey cows, distributed into two diets, a diet with no addition of anionic salt and one diet with addition of 0.25 kg/day of ammonium chloride. It was used a completely randomized design. Cows supplemented with anionic salt presented lower urinary pH and increase of blood contents of urea, calcium and magnesium. With the anionic diet, milk precipitated with lower ethanol concentration and it presented lower density, percentages of lactose, protein and immunoglobulin, but higher ionic calcium content. Supply of anionic diet during lactation resulted in metabolic acidosis, which altered the blood biochemical profile and milk physical-chemical characteristics