Finite size selleck compound scaling applied to the resistance threshold for a finite basic reproductive ratio rho of pathogen reveals that its difference from static percolation threshold (0.41) is inversely proportional to rho. Our formula for the basic reproductive ratio dependency of the resistance threshold produced an estimate for the critical
basic reproductive ratio (4.7) in a universally susceptible population, which is much larger than the corresponding critical value (1) in the mean-field model and nearly three times larger than the critical growth rate of a basic contact process (SIS model). Pair approximation reveals that the resistance threshold for preventing a global epidemic is factor 1/(1-eta) greater with spatially correlated planting than with random Selleckchem Rigosertib planting, where eta is initial correlation in host
genotypes between nearest-neighbour sites. Thus the eradication is harder with a positive spatial correlation (eta > 0) in mixed susceptible/resistant plantings, and is easier with a negative correlation (eta < 0). The effect of finite field size (L), which corresponded to the mean distance between sources of infections, is given by the increased resistance threshold (by the amount L-0.75) from its infinite size limit. Implications of these results on effective planting strategies in multi-line control plans are discussed. (C) 2011 Elsevier Ltd. All rights reserved.”
“Components of the brain’s dopaminergic system, such as dopamine receptors, undergo final maturation in adolescence. Exposure to social stress
during human adolescence contributes to substance abuse behaviors. We utilized a rat model of adolescent social stress to investigate the neural mechanisms underlying this correlation. Rats exposed to repeated social defeat in adolescence (P35-P39) exhibited increased conditioned place preference (CPP) for amphetamine (1 mg/kg) in adulthood (P70). In contrast, rats experiencing foot-shock during the same developmental period Clomifene exhibited amphetamine CPP levels similar to non-stressed controls. Our previous experiments suggested adolescent defeat alters dopamine activity in the mesocorticolimbic system. Furthermore, dopamine receptors have been implicated in the expression of amphetamine CPP. Therefore, we hypothesized that alteration to dopamine receptor expression in the mesocorticolimbic system may be associated with to heightened amphetamine CPP of adult rats exposed to adolescence defeat. We measured D1 and D2 dopamine receptor protein content in the medial prefrontal cortex, nucleus accumbens (NAc), and dorsal striatum following either adolescent social defeat or foot-shock stress and then adult amphetamine CPP. In controls, amphetamine CPP training reduced D2 receptor protein content in the NAc core.