Transport properties and spin accumulation in semiconductor two-dimensional electron gas/superconductor junctions

We extend the Blonder-Tinkham-Klapwijk (BTK) theory to study transport properties of semiconductor two-dimensional electron gas (2DEG)/superconductor junctions, including the Rashbar spin-orbit interaction in a 2DEG of finite width. The effects of Rashba spin-orbit interaction on the conductance are investigated, and a reduction of this conductance is found. A couple of well known results for quantized conductance are verified. Moreover, the averaged spin value and shape of spin fluctuation in the 2DEG are calculated. It is found that the y-component of the spin (S(y)) is even, while the x- and z-components are odd, with respect to the propagating mode index. Consequently, S(x) and S(z) are summed up to vanish, while S(y) accumulates to a finite value. S(y) is explicitly given and a spin-polarization in the y-direction is found in the 2DEG near the interface

边际医疗费用在探讨疾病合理住院日中的应用

目的探讨疾病的合理住院日,为有效缓解“看病贵,看病难“问题提供循证依据。方法利用厦门市民健康信息系统收集厦门市5家公立医院2008~2009年7个常见病种的病例资料,根据边际医疗费用计算各病种的合理住院日,同时获得住院日范围(P25,P75),在此基础上计算各病种的住院费用,并将其与实际费用进行比较。结果各病种合理住院日分别为:病毒性肝炎21.9(13.0,31.1)天;阑尾炎7.2(5.0,7.9)天;胃和十二指肠溃疡7.1(6.0,11.1)天;支气管肺炎6.6(5.3,7.3)天;子宫平滑肌瘤12.9(9.0,13.0)天;剖宫产7.6(7.0,8.0)天;自然分娩4.8(4.0,6.0)天。按照上述合理住院时间,各病种医疗费用降低共计635.9万元,其中以胃和十二指肠溃疡较为显著,为238.6万元,其人均医疗费用降低5667.0元。结论应用边际医疗费用探讨病种的合理住院日是一种科学可行的方法,制定病种合理的住院日可有效降低患者医疗费用

Andreev reflection effect on spin-polarized transport in ferromagnet/superconductor/ferromagnet double tunnel junctions

We present a phase diagram of a ferromagnetic superconductor (FS) in T-h plane with T the temperature and h the effective exchange field, in which a first-order phase-transition line separates the superconducting region from the normal-state region. The Josephson currents in an FS/I/FS junction (with I denoting thin insulating layers) are calculated as a function of the temperature, exchange field, and insulating barrier strength. It is found that the presence of h always suppresses the Josephson critical current at higher temperatures, or for weak barrier strength, or for a parallel configuration of the magnetic moments of two FS electrodes. The only exception that the critical current increases with h occurs if all three conditions are satisfied: at low temperatures, for strong barrier strength, and in an antiparallel configuration

Kink angle of multiwall carbon nanotubes due to interlayer interaction as viewed by elastic theory

The mechanism of kink formation in Multiwall Carbon Nanotubes (MWNTs) is studied by means of elastic theory with a consideration of the interlayer Frenkel-Kontorova interaction. The critical condition obtained through a calculation of the self-consistent correlation function suggests that a large asymmetric constant, after a competition with bending constant, can generate kink conformation in MWNTs. An evaluation of kink angle for kinked carbon MWNTs yields 33.6degrees and is in good agreement with the previous results observed through experiments

基于DEA方法的三级公立医院运行效率分析

目的以厦门市12家三级公立医院为例,分析评价三级公立医院运行效率情况及变化,为改进和提高其效率提供决策依据。方法选取2015-2016年厦门市卫生统计资料,采用数据包络分析方法(DEA)的BCC模型在规模报酬不变情况下计算其综合效率值、纯技术效率值与规模效率值,并通过Malmquist模型对生产效率变化趋势进行分析。进一步以2016年各医院投入-产出为例,用CCR模型计算各非DEA有效医院在投入、产出方面的投影值,以明确投入-产出的调整数量和调整比例。结果 2015年厦门市12家三级公立医院平均综合效率值为0.896,综合效率值为1即DEA有效的医院5家;2016年厦门市12家三级公立医院平均综合效率值为0.896,7家综合医院综合效率平均值为0.875,5家专科医院综合效率平均值为0.925,DEA有效的医院4家。2016年相较2015年同期,全要素生产率平均上升6.1%,6家医院全要素生产率提高,技术效率下降的3家医院均呈全要素生产率下降趋势。非DEA有效的医院通过提高医院自身的管理及经营水平达到DEA有效,总体可增加门急诊人数502751人次、出院人数9981人次以及63254万元业务收入。结论厦门市三级公立医院整体运行效率较好,专科医院整体效率优于综合型医院,半数医院处于效率上升趋势。技术进步对全要素生产率上升有较大影响,非DEA有效的医院在现有的投入下需要进一步提升产出,合适的规模以及技术的提高对于公立医院效率的提高有着重要的意义。国家自然科学基金项目(71874147)福建省自然科学基金面上项目(2017J01133

基于DEA模型分析我国公立医院运行效率

目的运用数据包络分析方法评价我国公立医院运行效率及变化,为公立医院提高运行效率、进一步完善和优化卫生资源配置提供决策依据。方法选取2011-2015年《中国卫生统计年鉴》等统计资料中的数据,采用数据包络分析法的CCR模型在规模报酬不变情况下计算综合效率值、BCC模型在规模报酬可变情况下计算纯技术效率值和规模效率值,对全国公立医院的运行效率进行分析,并通过Malmquist模型对生产效率变化趋势进行分析。结果 2014年全国31个省市公立医院平均综合效率值为0.887,综合效率值为1即DEA有效的省市10个,处于规模效率不变状态,其他省市是DEA非有效且处于规模效率递减状态;DEA有效省市主要集中在东部和西部;26个(83.88%)省市公立医院全要素生产率提高;非DEA有效省市若达到DEA有效可节省大量卫生资源投入、获得更多医院产出。结论近五年我国公立医院管理和技术方面效率有很大提高,但由于医院规模扩张过快反而降低了医院运行效率。适度的规模更有利于公立医院效率的提高,应该控制大型公立医院的发展规模,引导医院提高医疗技术和管理水平,促进内涵式发展,改善服务、改进管理,从而提高效率。国家自然科学基金项目(71403229

Gapless superconductivity in ferromagnet/superconductor junctions

We present a phase diagram of a ferromagnetic superconductor (FS) in T-h plane with T the temperature and h the effective exchange field, in which a first-order phase-transition line separates the superconducting region from the normal-state region. The Josephson currents in an FS/I/FS junction (with I denoting thin insulating layers) are calculated as a function of the temperature, exchange field, and insulating barrier strength. It is found that the presence of h always suppresses the Josephson critical current at higher temperatures, or for weak barrier strength, or for a parallel configuration of the magnetic moments of two FS electrodes. The only exception that the critical current increases with h occurs if all three conditions are satisfied: at low temperatures, for strong barrier strength, and in an antiparallel configuration

GTC Simulation of Ideal Ballooning Mode in Tokamak Plasmas

U.S. Department of Energy (DOE) SciDAC GSEP Center; National Special Research Program of ChinaIn the present paper, we first derive the eigenmode equation of the ideal ballooning mode in tokamak plasmas using a gyrokinetic equation. It is shown that the gyrokinetic eigenmode equation can be reduced to the magnetohydrodynamic (MHD) form in the long wavelength limit when kinetic effects are ignored. Then, the global gyrokinetic toroidal code (GTC) is applied for simulations of the edge-localized ideal ballooning modes. The obtained mode structures are compared with the results of ideal MHD simulations. The observed scaling of the linear growth rate with the toroidal mode number is consistent with the ideal MHD theory. The simulation results verify the GTC capability of simulating MHD processes in toroidal plasmas

Josephson current in ferromagnet-superconductor tunnel junctions

We present a phase diagram of a ferromagnetic superconductor (FS) in T-h plane with T the temperature and h the effective exchange field, in which a first-order phase-transition line separates the superconducting region from the normal-state region. The Josephson currents in an FS/I/FS junction (with I denoting thin insulating layers) are calculated as a function of the temperature, exchange field, and insulating barrier strength. It is found that the presence of h always suppresses the Josephson critical current at higher temperatures, or for weak barrier strength, or for a parallel configuration of the magnetic moments of two FS electrodes. The only exception that the critical current increases with h occurs if all three conditions are satisfied: at low temperatures, for strong barrier strength, and in an antiparallel configuration

第十八届美国理论与应用力学大会总结

1会议概况2018年6月5—9日,第18届美国理论与应用力学大会(18th U.S. National Congress of Theoretical and Applied Mechanics, USNCTAM2018)在美国芝加哥召开.本次大会由美国力学国家委员会和中国力学学会联合主办,旨在探讨和交流近四年世界范围内在理论和应用力学领域的基础研究、创新技术的最新进展,吸引了来自世界各地的近千名专家学