Zero field spin splitting in AlSb/InAs/AlSb quantum wells induced by surface proximity effects

InAs quantum well heterostructures are of considerable interest for mesoscopic device applications such as scanning probe and magnetic recording sensors, which require the channel to be close to the surface. Here we report on magnetotransport measurements of AlSb/InAs/AlSb Hall bars at a shallow depth of 20 nm. Analysis of the observed Shubnikov-de Haas oscillations and modeling show that spin splitting energies in excess of 2.3 meV occur at zero magnetic field. We conclude that the spin-splitting results from the Rashba effect due to the band bending in the quantum well. This is caused by substantial electron transfer from the surface to the quantum well and becomes significant when the quantum well is located near the surface.Comment: 14 pages, 2 figures. (To be published in APL

An analysis of the carbon balance of the Arctic Basin from 1997 to 2006

Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Tellus B 62 (2010): 455-474, doi:10.1111/j.1600-0889.2010.00497.x.This study used several model-based tools to analyze the dynamics of the Arctic Basin between 1997 and 2006 as a linked system of land-ocean-atmosphere C exchange. The analysis estimates that terrestrial areas of the Arctic Basin lost 62.9 Tg C yr-1 and that the Arctic Ocean gained 94.1 Tg C yr-1. Arctic lands and oceans were a net CO2 sink of 108.9 Tg C yr-1, which is within the range of uncertainty in estimates from atmospheric inversions. Although both lands and oceans of the Arctic were estimated to be CO2 sinks, the land sink diminished in strength because of increased fire disturbance compared to previous decades, while the ocean sink increased in strength because of increased biological pump activity associated with reduced sea ice cover. Terrestrial areas of the Arctic were a net source of 41.5 Tg CH4 yr-1 that increased by 0.6 Tg CH4 yr-1 during the decade of analysis, a magnitude that is comparable with an atmospheric inversion of CH4. Because the radiative forcing of the estimated CH4 emissions is much greater than the CO2 sink, the analysis suggests that the Arctic Basin is a substantial net source of green house gas forcing to the climate system.This study was supported, in part, by the NSF Arctic System Science Program as part of the Arctic Carbon Cycle Synthesis Project (ARC-0531047, 0531082, 0531119, and 0554811)

The effect of prehospital transport time, injury severity, and blood transfusion on survival of US military casualties in Iraq.

BACKGROUND: Reducing time from injury to care can optimize trauma patient outcomes. A previous study of prehospital transport of US military casualties during the Afghanistan conflict demonstrated the importance of time and treatment capability for combat casualty survival. METHODS: A retrospective descriptive analysis was conducted to analyze battlefield data collected on US military combat casualties during the Iraq conflict from March 19, 2003, to August 31, 2010. All casualties were analyzed by mortality outcome (killed in action, died of wounds, case fatality rate) and compared with Afghanistan conflict. Detailed data for those who underwent prehospital transport were analyzed for effects of transport time, injury severity, and blood transfusion on survival. RESULTS: For the total population, percent killed in action (16.6% vs. 11.1%), percent died of wounds (5.9% vs. 4.3%), and case fatality rate (10.0 vs. 8.6) were higher for Iraq versus Afghanistan (p \u3c 0.001). Among 1,692 casualties (mean New Injury Severity Score, 22.5; mortality, 17.6%) with detailed data, the injury mechanism included 77.7% from explosions and 22.1% from gunshot wounds. For prehospital transport, 67.6% of casualties were transported within 60 minutes, and 32.4% of casualties were transported in greater than 60 minutes. Although 97.0% of deaths occurred in critical casualties (New Injury Severity Score, 25-75), 52.7% of critical casualties survived. Critical casualties were transported more rapidly (p \u3c 0.01) and more frequently within 60 minutes (p \u3c 0.01) than other casualties. Critical casualties had lower mortality when blood was received (p \u3c 0.01). Among critical casualties, blood transfusion was associated with survival irrespective of transport time within or greater than 60 minutes (p \u3c 0.01). CONCLUSION: Although data were limited, early blood transfusion was associated with battlefield survival in Iraq as it was in Afghanistan. LEVEL OF EVIDENCE: Performance improvement and epidemiological, level IV