Travelers' Diarrhea in Children Visiting Tropical Countries

We studied a group of 174 Portuguese children (aged 2 mo-16 y) who mostly traveled to tropical Portuguese-speaking countries and found an attack rate of 21.8% for travelers' diarrhea, much lower than previously described. We also showed that African rate analysis by region may hide significant differences between countries

On the probability distributions of the force and potential energy for a system with an infinite number of random point sources

In this work, we study the probability distribution for the force and potential energy of a test particle interacting with $N$ point random sources in the limit $N\rightarrow\infty$. The interaction is given by a central potential $V(R)=k/R^{\delta-1}$ in a $d$-dimensional euclidean space, where $R$ is the random relative distance between the source and the test particle, $\delta$ is the force exponent, and $k$ is the coupling parameter. In order to assure a well-defined limit for the probability distribution of the force and potential energy, we { must} renormalize the coupling parameter and/or the system size as a function of the number $N$ of sources. We show the existence of three non-singular limits, depending on the exponent $\delta$ and the spatial dimension $d$. (i) For $\delta<d$ the force and potential energy { converge} to their respective mean values. This limit is called Mean Field Limit. (ii) For $\delta>d+1$ the potential energy converges to a random variable and the force to a random vector. This limit is called Thermodynamic Limit. (iii) For $d<\delta<d+1$ the potential energy converges to its mean and the force to a random vector. This limit is called Mixed Limit Also, we show the existence of two singular limits: (iv) for $\delta=d$ the potential energy converges to its mean and the force to zero, and (v) for $\delta=d+1$ the energy converges to a finite value and the force to a random vector.Comment: 25 pages, 5 tables, Preprint Articl

Proteomic signatures uncover the early key players on Vitis vinifera cv. “Regent - Plasmopara viticola crosstalk

info:eu-repo/semantics/publishedVersio

Nanotubos de carbono para processos de tratamento de águas

Oxidantes como o oxigénio molecular, o ozono e o peróxido de hidrogénio são utilizados nos tratamentos de águas residuais por via química oxidativa podendo atuar por si próprios, ou ser ativados por meio de um catalisador, ou fotocatalisador, adequado. Sendo os tratamentos químicos processos definitivos por natureza, é possível apontar à mineralização completa dos poluentes presentes. Contudo, raramente é esse o caso, quando se procura uma solução racional do ponto de vista económico. No caso de efluentes industriais recorre-se muitas vezes a tratamentos diferenciados, com vista a uma degradação oxidativa parcial