Objective: To examine the brain structural correlates of age at onset in pati ents with Alzheimer’s disease. Methods: We studied nine patients with early on set (age ≤ 65 years), nine with late onset (age >65) Al...Objective: To examine the brain structural correlates of age at onset in pati ents with Alzheimer’s disease. Methods: We studied nine patients with early on set (age ≤ 65 years), nine with late onset (age >65) Alzheimer’s disease (EOA D and LOAD, respectively) of mild-moderate severity, and 26 controls who were stratified into younger (YC, age ≤ 65, n = 9) and older (OC, age >65, n = 17) s ubjects. The patients were closely matched for clinical severity: 3/2/3/1 patien ts had clinical dementia rating of 0.5/1/2/3, respectively, in both the groups. High resolution magnetic resonance images of the brain of the EOAD and YC groups and the LOAD and OC groups were compared on a voxel by voxel basis with statist ical parametric mapping to detect areas specifically atrophic. Results: The pati ents with EOAD showed greater neocortical atrophy at the temporoparietal junctio n while the patients with LOAD showed greater hippocampal atrophy. The results c ould not be accounted for by the apolipoprotein E genotype. Conclusions: Since g enetic factors are believed to play a relevant pathogenetic role in EOAD and env ironmental factors in LOAD, genetic and environmental factors may differentially predispose the neocortical and limbic areas to the development of Alzheimer’s neuropathology.展开更多
This paper presents a comparison among different hydrodynamic models for the analysis of the unsteady loads delivered by a marine propeller working in an axial, non-uniform inflow. Specifically, for a propeller subjec...This paper presents a comparison among different hydrodynamic models for the analysis of the unsteady loads delivered by a marine propeller working in an axial, non-uniform inflow. Specifically, for a propeller subjected to a wake-field dominated by local high-frequency changes in space, the unsteady hydroloads predicted by the Nakatake formulation are compared with those given by the Theodorsen and Sears theories, respectively. Drawbacks and potentialities of these approaches are highlighted to assess a computationally efficient hydrodynamic solver for the analysis of operating conditions where propeller blades are significantly perturbed by a multi-harmonic onset-flow. Guidelines coming from this investigation may drive the choice of a fast and reliable unsteady propeller modeling that represents a good trade-off between accuracy of simulation and cost of computation within implementation in Computational Fluid Dynamics （CFD） solvers. The hydrodynamic formulations herein proposed are validated through numerical comparisons with the （accurate but computationally expensive） propeller loads predicted by a fully 3-D panel-method Boundary Element Method （BEM） solver, suited for the analysis of propellers operating in a complex hydrodynamic environment.展开更多
文摘Objective: To examine the brain structural correlates of age at onset in pati ents with Alzheimer’s disease. Methods: We studied nine patients with early on set (age ≤ 65 years), nine with late onset (age >65) Alzheimer’s disease (EOA D and LOAD, respectively) of mild-moderate severity, and 26 controls who were stratified into younger (YC, age ≤ 65, n = 9) and older (OC, age >65, n = 17) s ubjects. The patients were closely matched for clinical severity: 3/2/3/1 patien ts had clinical dementia rating of 0.5/1/2/3, respectively, in both the groups. High resolution magnetic resonance images of the brain of the EOAD and YC groups and the LOAD and OC groups were compared on a voxel by voxel basis with statist ical parametric mapping to detect areas specifically atrophic. Results: The pati ents with EOAD showed greater neocortical atrophy at the temporoparietal junctio n while the patients with LOAD showed greater hippocampal atrophy. The results c ould not be accounted for by the apolipoprotein E genotype. Conclusions: Since g enetic factors are believed to play a relevant pathogenetic role in EOAD and env ironmental factors in LOAD, genetic and environmental factors may differentially predispose the neocortical and limbic areas to the development of Alzheimer’s neuropathology.
文摘This paper presents a comparison among different hydrodynamic models for the analysis of the unsteady loads delivered by a marine propeller working in an axial, non-uniform inflow. Specifically, for a propeller subjected to a wake-field dominated by local high-frequency changes in space, the unsteady hydroloads predicted by the Nakatake formulation are compared with those given by the Theodorsen and Sears theories, respectively. Drawbacks and potentialities of these approaches are highlighted to assess a computationally efficient hydrodynamic solver for the analysis of operating conditions where propeller blades are significantly perturbed by a multi-harmonic onset-flow. Guidelines coming from this investigation may drive the choice of a fast and reliable unsteady propeller modeling that represents a good trade-off between accuracy of simulation and cost of computation within implementation in Computational Fluid Dynamics （CFD） solvers. The hydrodynamic formulations herein proposed are validated through numerical comparisons with the （accurate but computationally expensive） propeller loads predicted by a fully 3-D panel-method Boundary Element Method （BEM） solver, suited for the analysis of propellers operating in a complex hydrodynamic environment.
