Transportation and land-use preferences and residents’ neighborhood choices: the sufficiency of compact development in the Atlanta region

This paper analyzes the transportation and land-use preference and actual neighborhood choices of a sample of 1,455 residents of metro Atlanta. We develop a stated-preference scale on which desires for neighborhood type are gauged, from preferences for low-density, auto-oriented environments to desires for compact, walkable, and transit-oriented neighborhoods. This scale is then related to desires for change in one’s own neighborhood characteristics after a hypothetical move. If all neighborhood preferences were equally likely to be satisfied, then neighborhood preferences would not be correlated with a desire for change. By contrast, in the current study, stronger preferences for a more walkable environment are associated with greater desire for change in one’s neighborhood characteristics. This suggests an undersupply of compact, walkable, and transit-friendly neighborhood types relative to current demand.

船体纵骨典型节点疲劳裂纹扩展寿命评估

基于有限元软件ABAQUS,结合虚拟裂纹闭合法、裂纹扩展判据及子结构技术,应用脚本语言Python开发出模拟疲劳裂纹扩展的程序(FCG-System)。对含初始裂纹的油船纵骨典型节点在侧面压力作用下进行疲劳裂纹扩展数值模拟,并探讨了软趾、背肘板及防倾肘板对疲劳裂纹扩展路径和寿命的影响。结果表明,增设软趾、背肘板或防倾肘板都会使裂纹扩展路径曲率增大,且软趾、防倾肘板可使裂纹扩展寿命增大,背肘板可使裂纹扩展寿命减小。     

Transport infrastructure and long-run economic growth in OECD countries

This paper provides an empirical evaluation of the growth impact of public infrastructure in a panel of 18 OECD countries during 1870–2009. This study goes beyond the traditional analysis of growth accounting models by exploring the indirect effect of stock of core infrastructure on output growth through its impact on productivity. Constructing a long-run historical dataset on infrastructural capital formation spanning from 1870, estimated results show that growth in both labour productivity and total factor productivity are positively, but not substantially, influenced by growth in the stock of infrastructure. Furthermore, applying the system GMM technique (Generalised Method of Moments) revels that although rate of returns to investment in infrastructure exceed the private rate in OECD countries, it is not as high as positive externalities associated with investment in equipment and structure investment.     

Numerical study on fatigue crack growth at a web-stiffener of ship structural details by an objected-oriented approach in conjunction with ABAQUS

It is necessary to manage the fatigue crack growth (FCG) once those cracks are detected during in-service inspections. This is particular critical as high strength steels are being used increasingly in ship and offshore structures. In this paper, a simulation program (FCG-System) is developed utilizing the commercial software ABAQUS with its object-oriented programming interface to simulate the fatigue crack path and to compute the corresponding fatigue life. In order to apply FCG-System in large-scale marine structures, the substructure modeling technique is integrated in the system under the consideration of structural details and load shedding during crack growth. Based on the nodal forces and nodal displacements obtained from finite element analysis, a formula for shell elements to compute stress intensity factors is proposed in the view of virtual crack closure technique. Neither special singular elements nor the collapsed element technique is used at the crack tip. The established FCG-System cannot only treat problems with a single crack, but also handle problems with multiple cracks in case of simultaneous but uneven growth. The accuracy and the robustness of FCG-System are demonstrated by two illustrative examples. No stability and convergence difficulties have been encountered in these cases and meanwhile, insensitivity to the mesh size is confirmed. Therefore, the FCG-System developed by authors could be an efficient tool to perform fatigue crack growth analysis on marine structures.     

窄谱中波紫外线对角质形成细胞肝素结合表皮生长因子样生长因子mRNA的影响

目的研究窄谱中波紫外线(NB-UVB)对培养的正常人角质形成细胞(KC)增殖和肝素结合表皮生长因子样生长因子(HB-EGF)mRNA表达的影响。方法用50 mJ/cm2和100 mJ/cm2NB-UVB照射正常人KC后继续培养12 h,用MTT法和实时荧光定量RT-PCR法分别检测KC增殖和HB-EGF mRNA的改变。结果NB-UVB照射正常人KC后,可剂量依赖抑制KC的增殖和上调HB-EGF mRNA的表达。50 mJ/cm2和100 mJ/cm2NB-UVB照射后,分别使KC增殖抑制5.4%和8.7%,使HB-EGF mRNA增加到正常对照组的1.7倍和2.5倍。结论NB-UVB抑制KC的增殖部分是通过上调HB-EGF的表达介导的。     

16MnR钢焊接接头疲劳裂纹扩展行为及裂纹闭合效应的研究

测定了16MnR母材、焊缝以及热影响区三种试件的疲劳裂纹扩展速率和在四个应力比(R=0.1,0.3,0.5,0.8)下的门槛值。得到了在疲劳裂纹扩展中速区和低速区的扩展规律。此外,还研究了残余应力和应力比对该钢种疲劳门槛值的影响,以及近门槛值域内疲劳裂纹的闭合效应。     

氧化苦参碱在大鼠肾间质纤维化进程中的保护作用

目的探讨氧化苦参碱对大鼠肾间质纤维化进程的干预作用,并阐明其部分机制。方法40只雄性SD大鼠,随机分为假手术组、模型组、苯那普利组、氧化苦参碱大剂量组和小剂量组。以单侧输尿管结扎术建立输尿管梗阻的动物模型。术后第14天取术侧肾组织行HE、Masson染色及转化生长因子-β1(TGF-β1)、α-平滑肌肌动蛋白(-αSMA)和Ⅲ型胶原(ColⅢ)免疫组化检测,并运用图像分析系统做半定量分析。结果经氧化苦参碱干预后,梗阻侧肾脏的-αSMA、TGF-β1和ColⅢ的表达均显著低于模型组(P<0.01);大剂量氧化苦参碱组均低于苯那普利组(P<0.05);氧化苦参碱大剂量组和小剂量组之间无显著性差异(P>0.05)。结论氧化苦参碱可能是通过降低TGF-β1等细胞因子的表达而减少细胞外基质(ECM)产生细胞的活化,从而减少ECM的沉积,达到抗肾间质纤维化的作用。     

胰岛素样生长因子-1与糖尿病下肢血管病变的关系

目的分析血清胰岛素样生长因子-1（IGF-1）水平在2型糖尿病下肢血管病变中的变化规律，探讨IGF-1在糖尿病大血管病变发病机制中的作用，为糖尿病大血管病变的防治提供依据。方珐选择74例2型糖尿病患者和15例健康人，常规测身高、体重、血压、血糖、空腹胰岛素、糖化血红蛋白、血脂、尿白蛋白排泄率；用ELISA法测血清IGF-1水平；用多普勒超声进行双下肢动脉病变检查。结果①糖尿病患者血清IGF-1水平明显高于对照组；②糖尿病合并下肢动脉血管病变时血清IGF-1水平明显高于无下肢动脉血管病变组，且血清IGF-1水平与下肢动脉血管病变的严重程度呈正相关；③糖尿病下肢动脉血管病变的严重程度与尿白蛋白排泄率、病程、血总胆固醇（TC）、低密度脂蛋白（LDL）水平呈正相关。结论血清IGF-1水平可以反映糖尿病下肢血管病变的严重程度，对糖尿病大血管病变的诊断有参考价值，并有可能作为糖尿病大血管病变治疗的新靶点。     

脑缺血组织nestin蛋白重新表达及其与碱性成纤维细胞生长因子表达的关系

目的　研究缺血脑组织nestin蛋白重新表达和碱性成纤维细胞生长因子 (bFGF)表达的关系。方法　建立永久性脑缺血大鼠模型 ,采用免疫组化染色方法 ,观察脑缺血后 1、3、7、14、2 8d脑组织nestin蛋白和bFGF的表达。结果　缺血后 1～ 3d缺血灶附近nestin免疫阳性细胞大量出现 ,缺血 7d开始减少 ;而bFGF免疫阳性细胞在缺血 14d大量出现 ,缺血 2 8d开始减少。结论　缺血脑组织重新表达nestin蛋白不需要bFGF的营养和支持 ,缺血脑组织周围的nestin免疫阳性细胞来源于重演胚胎发育过程的星形胶质细胞     

PRODUCTION OF PARATHYROID HORMONE－RELATED PROTEIN （PTHrP） BY A HUMAN HEPATOMA CELL LINE

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