Geometric clusters in the overlap of the Ising model

We study the percolation properties of geometrical clusters defined in the overlap space of two statistically independent replicas of a square-lattice Ising model that are simulated at the same temperature. In particular, we consider two distinct types of clusters in the overlap, which we dub soft- and hard-constraint clusters, and which are subsets of the regions of constant spin overlap. By means of Monte Carlo simulations and a finite-size scaling analysis we estimate the transition temperature as well as the set of critical exponents characterizing the percolation transitions undergone by these two cluster types. The results suggest that both soft- and hard-constraint clusters percolate at the critical temperature of the Ising model and their critical behavior is governed by the correlation-length exponent ν=1 found by Onsager. At the same time, they exhibit nonstandard and distinct sets of exponents for the average cluster size and percolation strength

Reclassifying bioterrorism risk: Are we preparing for the proper pathogens?

Summary: Existing classifications of potential biological weapons, acknowledge only limited important parameters of biological weapon potential. Certain pathogen factors would further influence the outcome of a potential attack in context with social and political aspects of the time and space of the attack. The importance of these factors was investigated through various attack scenarios that have been developed by the authors, and an individual score for each of these factors was calculated, based on the overall effect their variation had in the scenario outcome. A new classification score for potential biological weapons was subsequently developed, one, which drastically alters the perception of risk for certain pathogens, such as filoviruses and anthrax. This frame further allows for more accurate evaluation of the bioweapon potential of agents such as avian flu. Recognition of intervening factors and proper assessment of the actual risk might augment in proper distribution of interest and funds on relevant medical research. Keywords: Bioterrorism, Risk, Classificatio

Corrections to scaling in geometrical clusters of the 2D Ising model

We study the scaling of the average cluster size and percolation strength of geometrical clusters for the two-dimensional Ising model. By means of Monte Carlo simulations and a finite-size scaling analysis we discuss the appearance of corrections to scaling for different definitions of cluster sets. We find that including all percolating clusters, or excluding only clusters that percolate in one but not the other direction, leads to smaller corrections to scaling for the average cluster size as compared to the other definitions considered. The percolation strength is less sensitive to the definitions used.Comment: 6 pages, 2 figures, 2 tables, XXXII IUPAP Conference on Computational Physic

The liver in brucellosis

Background & Aims: Brucellosis involves the liver in varying ways, ranging from benign subclinical increases in serum aminotransferase levels to ominous chronic suppurative disease. Data on histopathology of the liver in brucellosis are scarce and contradictory. We sought to determine the liver histologic patterns present in a series of brucellosis patients and review the existing knowledge about liver involvement in this worldwide, prevalent zoonotic infection. Methods: Fourteen patients from 2 referral centers were retrospectively studied. They had brucellosis caused by Brucella melitensis and had undergone liver biopsy at the time of diagnosis. Results: All patients exhibited granuloma formation in the liver parenchyma and in the majority in portal spaces. Varying degrees of cellular infiltration of parenchymal tissue and portal spaces, giant cells in granulomas, parenchymal necroses, and Kupffer’s cell hyperplasia were also noted. No significant epidemiological or clinical correlations with liver involvement were exhibited. Thus, liver involvement was not increased in men vs women, young vs old patients, or complicated vs uncomplicated disease. Conclusions: The liver is involved in Brucella melitensis infection contrary to past beliefs. Different histologic patterns can be observed in liver involvement in brucellosis, the most common being granuloma formation. The pathogenetic role of brucellosis in development of liver fibrosis and cirrhosis remains limited and understudied