Traditional approaches to the study of fragmented landscapes invoke an island-ocean model and assume that the nonhabitat matrix surrounding remnant patches is uniform. Patch isolation, a crucial parameter to the predictions of island biogeography and metapopulation theories, is measured by distance alone. To test whether the type of interpatch matrix can contribute significantly to patch isolation, I conducted a mark-recapture study on a butterfly community inhabiting meadows in a naturally patchy landscape. I used maximum likelihood to estimate the relative resistances of the two major matrix types (willow thicket and conifer forest) to butterfly movement between meadow patches. For four of the six butterfly taxa (subfamilies or tribes) studied, conifer was 3-12 times more resistant than willow. For the two remaining taxa (the most vagile and least vagile in the community), resistance estimates for willow and conifer were not significantly different, indicating that responses to matrix differ even among closely related species. These results suggest that the surrounding matrix can significantly influence the "effective isolation" of habitat patches, rendering them more or less isolated than simple distance or classic models would indicate. Modification of the matrix may provide opportunities for reducing patch isolation and thus the extinction risk of populations in fragmented landscapes.
The occupancy of caches has tended to be dominated by the logic bit value '0' approximately 75% of the time. Periodic bit flipping can reduce this to 50%. Combining cache power saving strategies with bit flipping can lower the effective logic bit value '0' occupancy ratios even further. We investigate how Negative Bias Temperature Instability (NBTI) affects different power saving cache strategies employing symmetric and asymmetric 6-transistor (6T) and 8T Static Random Access Memory (SRAM) cells. We notice that greater than 38% to 66% of the recovery in stability parameters (SNM and WNM) under different power saving cache strategies have been achieved for different SRAM cells based caches. We also study the process variations effect along with NBTI for 32nm and 45nm technology node. It is observed that the rate of recovery in asymmetric SRAM cells based caches is slightly higher than the symmetric and 8T SRAM cells based caches.
3D integration of multiple active layers into a single chip is a viable technique that greatly reduces the length of global wires by providing vertical connections between layers. However, dissipating the heat generated in the 3D chips possesses a major challenge to the success of the technology and is the subject of active current research. Since the generated heat degrades the performance of the chip, thermally insensitive/adaptive circuit design techniques are required for better overall system performance. In this paper, we propose a thermally adaptive 3D clocking scheme that dynamically adjusts the driving strengths of the clock buffers to reduce the clock skew between terminals. We investigate the relative merits and demerits of two alternative clock tree topologies in this work. Simulation results demonstrate that our adaptive technique is capable of reducing the skew by 61.65% on the average, leading to much improved clock synchronization and design performance in the 3D realm.
This study demonstrates that silicone is not a necessary component of occlusive dressings in the treatment of hypertrophic scars. The pathogenesis of hypertrophic scars is further elucidated by demonstrating that there is molecular evidence for extensive connective tissue remodeling occurring during occlusive dressing therapy.
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