Demonstration of Forward Inter-band Tunneling in GaN by Polarization Engineering

We report on the design, fabrication, and characterization of GaN interband tunnel junction showing forward tunneling characteristics. We have achieved very high forward tunneling currents (153 mA/cm2 at 10 mV, and 17.7 A/cm2 peak current) in polarization-engineered GaN/InGaN/GaN heterojunction diodes grown by plasma assisted molecular beam epitaxy. We also report the observation of repeatable negative differential resistance in interband III-Nitride tunnel junctions, with peak-valley current ratio (PVCR) of 4 at room temperature. The forward current density achieved in this work meets the typical current drive requirements of a multi-junction solar cell.Comment: 3 figure

Investigation of a Locus on Chromosome 9 for Contributions to Pulmonary Hypertension Syndrome in Broilers

Although the ascites syndrome in chickens has been investigated for years, it continues to inflict financial losses to the world poultry industry. It is estimated that 8% of the 361 million broiler deaths are due to ascites leading to losses of millions of dollars annually. Efforts to curb the incidence of ascites are typically designed to slow early growth. This limits the birds\u27 ability to show its true genetic potential and impacts later yields. In 1994 lines divergent for susceptibility to ascites were established from a commercial sire line through sibling selection of birds reared at local altitude after testing siblings reared under simulated high altitude conditions. We used a whole genome SNP survey in our lines to identify regions associated with susceptibility. Seven potential regions were identified. Using microsatellite markers on chromosome 9 linked to genes with known contributions to Pulmonary Hypertension Syndrome, a survey of the lines (Generation -14) was accomplished. This survey revealed that the selected lines changed in allele frequency for the markers as compared to each other and the line of origin. Changes were consistent with patterns of susceptibility and resistance to ascites. In addition to the research populations, it was determined that three commercial lines are also segregating for resistance related alleles from these regions. The data support the predictive nature of these loci in that, the presence of a specific genotype is associated with resistance to ascites. These microsatellite markers show utility in several different lines and therefore, could be used for marker assisted selection to improve ascites resistance. Finally, economic impact of utilizing these markers was evaluated. Significant differences were found among the genotypes of a marker for absolute breast, percentage breast and percentage leg. Therefore, if these markers have to be super-imposed in commercial selection programs, there could be compromises on traits of economic importance

Locality-Aware Dynamic Task Graph Scheduling

Dynamic task graph schedulers automatically balance work across processor cores by scheduling tasks among available threads while preserving dependences. In this paper, we design NabbitC, a provably efficient dynamic task graph scheduler that accounts for data locality on NUMA systems. NabbitC allows users to assign a color to each task representing the location (e.g., a processor core) that has the most efficient access to data needed during that node’s execution. NabbitC then automatically adjusts the scheduling so as to preferentially execute each node at the location that matches its color—leading to better locality because the node is likely to make local rather than remote accesses. At the same time, NabbitC tries to optimize load balance and not add too much overhead compared to the vanilla Nabbit scheduler that does not consider locality. We provide a theoretical analysis that shows that NabbitC does not asymptotically impact the scalability of Nabbit . We evaluated the performance of NabbitC on a suite of memory intensive benchmarks. Our experiments indicates that adding locality awareness has a considerable performance advantage compared to the vanilla Nabbit scheduler. In addition, we also compared NabbitC to OpenMP programs for both regular and irregular applications. For regular applications, OpenMP achieves perfect locality and perfect load balance statically. For these benchmarks, NabbitC has a small performance penalty compared to OpenMP due to its dynamic scheduling strategy. For irregular applications, where OpenMP can not achieve locality and load balance simultaneously, we find that NabbitC performs better. Therefore, NabbitC combines the benefits of locality- aware scheduling for regular applications (the forte of static schedulers such as those in OpenMP) and dynamically adapting to load imbalance (the forte of dynamic schedulers such as Cilk Plus, TBB, and Nabbit)