[1] Permafrost degradation is regarded as a crucial factor influencing the stability of steep rockwalls in alpine areas. Discernment of zones of fast temperature changes requires knowledge about the temperature distribution and evolution at and below the surface of steep rock. In complex high-mountain topography, strong lateral heat fluxes result from topography and variable surface temperatures and profoundly influence the subsurface thermal field. To investigate such three-dimensional effects, numerical experimentation was conducted using typical idealized geometries of high-mountain topography, such as ridges, peaks, or spurs. The approach combines a surface energy balance model with a three-dimensional ground heat conduction scheme to investigate belowground temperature distribution and permafrost occurrence in high-mountain topography. Time-dependent simulations are based on scenario data gained from regional climate models. Results indicate complex three-dimensional patterns of temperature distribution and heat flow density below mountainous topography for equilibrium conditions, which are additionally perturbed by transient effects. Permafrost occurs at many locations where temperatures at the surface do not indicate it, e.g., on the south face of ridges or below the edges of a peak. The modeling tools applied have potential for a number of studies in high mountains addressing questions related to permafrost distribution and evolution at depth in real topographies, for instance, the reanalysis of temperature-related instabilities.

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The reduced risk of dementia in high-educated individuals has been suggested to reflect brain reserve capacity. In the present study, we determined the association between integrity of white matter microstructure and education separately in twenty-one patients with clinically probable Alzheimer's disease (AD) and 18 healthy elderly subjects. We used fractional anisotropy derived from high-resolution diffusion-tensor weighted imaging at 3 Tesla as an in vivo marker of white matter microstructure. Based on multivariate network analysis, more years of education were associated with reduced white matter integrity of medial temporal lobe areas and association fiber tracts when age, gender, and dementia severity had been controlled for (p < 0.001). In controls, higher education was associated with greater white matter integrity in medial temporal lobe areas and association fiber tracts (p < 0.001). In multiple regression models, education was the main factor accounting for fiber tract integrity even when occupation was taken into account. Reduced fiber tract integrity with higher education at the same level of cognitive impairment in AD patients and higher fiber tract integrity with higher education in similar white matter areas in cognitively healthy controls agrees with the hypothesis that white matter microstructure may contribute to brain reserve capacity in humans.

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IntroductionThe characterization of flow behavior in fractured rock under disturbed conditions is important for the disposal of radioactive waste, geothermal utilization by hot dry rock (HDR) systems, oil and gas production from fractured reservoirs, and water production from fractured rock. Recent activity in developing HDR systems has succeeded in attracting both public and political attention and has produced new field and theoretical results that could have a significant influence on other hydrologic disciplines. HDR systems are attractive because they offer the prospect of producing electrical and thermal energy from deep rock formations in areas of high population density since they primarily require only hot (preferably T > 150øC for electrical production) crystalline rocks at drillable depths