Abstract. We present a new benchmark suite for parallel computers. SPEComp targets mid-size parallel servers. It includes a number of science/engineering and data processing applications. Parallelism is expressed in the OpenMP API. The suite includes two data sets, Medium and Large, of approximately 1.6 and 4 GB in size. Our overview also describes the organization developing SPEComp, issues in creating OpenMP parallel benchmarks, the benchmarking methodology underlying SPEComp, and basic performance characteristics.
The band-edge exciton fine structure of wurtzite CdSe nanocrystals is investigated by a plane-wave pseudopotential method that includes
spin−orbit coupling, screened electron−hole Coulomb interactions, and exchange interactions. Large-scale, systematic simulations have been
carried out on quantum dots, nanorods, nanowires, and nanodisks. The size and shape dependence of the exciton fine structure is explored
over the whole diameter−length configuration space and is explained by the interplay of quantum confinement, intrinsic crystal-field splitting,
and electron−hole exchange interactions. Our results show that the band-edge exciton fine structure of CdSe nanocrystals is determined by
the origin of their valence-band single-particle wave functions. Nanocrystals where the valence-band maximum originates from the bulk A
band have a “dark” ground-state exciton. Nanocrystals where the valence-band maximum is derived from the bulk B band have a “quasi-bright” ground-state exciton. Thus, the diameter−length configuration map can be divided into two regions, corresponding to dark and quasi-bright ground-state excitons. We find that the dark/quasi-bright ground-state exciton crossover is not only diameter-dependent but also length-dependent, and it is characterized by a curve in the two-parameter space of diameter and length.
Follow-up surveillance after EVAR is less intense in practice environments outside of clinical trials. Patients with incomplete follow-up have higher fatal complication rates than patients with frequent follow-up. These data expose a potential under-appreciated limitation of EVAR, questioning whether the findings in clinical trials defining the efficacy of EVAR can be routinely extrapolated to ordinary practice.
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