The maps of mean PD173074 in vitro diffusivity (MD) and fractional anisotropy (FA) were computed separately for positive (p: pMD and pFA) and negative (n: nMD and nFA) polarities, and we computed the geometric mean (gm) of the DT-MRI to obtain the gmFA and gmMD with reducing the background gradient effects. Regional variations were assessed across the groups using one-way
analysis of variance.
Increased regional gmMD values in the AD subjects, as compared to the regional gmMD values in the MCI and CN subjects, were found primarily in the frontal, limbic, and temporal lobe regions. We also found increased nMD and pMD values in the AD subjects compared to those values in the MCI and CN subjects, including in the temporal lobe and the left limbic parahippocampal gyrus white matter. Results of comparisons among the three methods showed that the left limbic parahippocampal gyrus and right temporal gyrus were the increased MD in the AD patients for all three methods.
Background gradients affect the DT-MRI measurements in AD patients. Geometric average diffusion measures can be useful to minimize the intrinsic local magnetic susceptibility variations in brain tissue.”
“In the face of stochastic climatic perturbations, the overall stability of an ecosystem will be
determined by the balance between its resilience and its resistance, but their relative importance is still unknown. Using aquatic food web models we study ecosystem stability as a function Dorsomorphin research buy of food web complexity. We measured three dynamical stability properties: resilience, resistance, and variability. Specifically, we evaluate how a decrease in the strength of predator-prey interactions with food web complexity, reflecting a decrease in predation efficiency with the number of prey per
predator, affects the overall stability of the ecosystem. We find that in mass conservative ecosystems, a lower interaction strength slows down the mass cycling rate in the system and this increases its resistance to perturbations of the growth rate of primary producers. Furthermore, we show that the overall stability of the food webs is mostly given by their resistance, and not by their resilience. Resilience and resistance display opposite trends, although they Thymidylate synthase are shown not to be simply opposite concepts but rather independent properties. The ecological implication is that weaker predator-prey interactions in closed ecosystems can stabilize food web dynamics by increasing its resistance to climatic perturbations. (c) 2010 Elsevier Ltd. All rights reserved.”
“The clinical efficacy of thrombolysis in stroke patients is explained by the increased rate of recanalization, which limits infarct growth. However, the efficacy could also be explained by the protection of specific sites of the brain. Here, we investigate where is this outcome-related tissue at risk using voxel-based analysis.