预应力施工技术在建筑工程中的应用

笔者结合预应力混凝土结构的工作原理,介绍了预应力施工技术在桌工程中的应用,从预应力筋孔道铺设、预应力筋安装及张拉、孔道灌浆及封锚等方面阐述了预应力施工方法,为同类工程提供一定参考.     

A≤10原子核快中子散射的光学模型分析

应用球形光学模型,系统地分析了~3He、~6Li、~7Li、~9Be和~10B的快中子散射资料。所用的光学势为包含了面吸收和自旋轨道耦合项的Woods-Saxon型势。取实部(氵弓尔)散参数和面吸收深度为入射能量的线性函数,结果表明实部(氵弓尔)散参数随入射能量增加而缓慢减少。所得结果与实验资料符合得较好。     

The adhesion receptor GPR56 is activated by extracellular matrix collagen III to improve β-cell function

Aims

G-protein coupled receptor 56 (GPR56) is the most abundant islet-expressed G-protein coupled receptor, suggesting a potential role in islet function. This study evaluated islet expression of GPR56 and its endogenous ligand collagen III, and their effects on β-cell function.

Methods

GPR56 and collagen III expression in mouse and human pancreas sections was determined by fluorescence immunohistochemistry. Effects of collagen III on β-cell proliferation, apoptosis, intracellular calcium ([Ca²⁺]_i) and insulin secretion were determined by cellular BrdU incorporation, caspase 3/7 activities, microfluorimetry and radioimmunoassay, respectively. The role of GPR56 in islet vascularisation and innervation was evaluated by immunohistochemical staining for CD31 and TUJ1, respectively, in pancreases from wildtype (WT) and Gpr56^?/? mice, and the requirement of GPR56 for normal glucose homeostasis was determined by glucose tolerance tests in WT and Gpr56^?/? mice.

Results

Immunostaining of mouse and human pancreases revealed that GPR56 was expressed by islet β-cells while collagen III was confined to the peri-islet basement membrane and islet capillaries. Collagen III protected β-cells from cytokine-induced apoptosis, triggered increases in [Ca²⁺]_i and potentiated glucose-induced insulin secretion from WT islets but not from Gpr56^?/? islets. Deletion of GPR56 did not affect glucose-induced insulin secretion in vitro and it did not impair glucose tolerance in adult mice. GPR56 was not required for normal islet vascularisation or innervation.

Conclusion

We have demonstrated that collagen III improves islet function by increasing insulin secretion and protecting against apoptosis. Our data suggest that collagen III may be effective in optimising islet function to improve islet transplantation outcomes, and GPR56 may be a target for the treatment of type 2 diabetes.

     

电子商务平台中的卖家甄别机制

该文研究了电子商务平台如何通过甄别机制区分不同的卖家,并进一步分析了甄别机制对于平台收费结构和利润的影响。通过构建并求解一个双边架构的甄别模型,并进行比较静态分析,研究表明:接入费的结构与平台甄别能力密切相关,当甄别能力较弱时,平台对低质卖家收费较低甚至提供补贴。而随着甄别能力提升,平台的定价能力增强。在一定范围内,甄别能力对平台利润有正影响。因此,甄别功能的建立和完善,能够增强平台的盈利能力,提升平台价值。     

一般化凸空间上的共存定理与有限交性质

在本文，我们根据已有的一般化凸空间上的不动点定理给出了两个共存定理，并利用此定理讨论了有限交性质，这些结论对文献[1]和[2]中的相应结论进行了改进和一般化．     

道路水域对中国林蛙繁殖的影响

2011—2014年,在长白山自然保护区选取3条长10 km的道路样带,分析水体类型、水体面积、水深、距道路距离、相对潮湿度和干扰因素等6个生境因子对中国林蛙产卵量及卵损失率的影响.结果显示:3条样带共调查到479个水体,记录1 451个卵;每个水体样本平均卵数量为(3.02±0.322)个;卵总损失数量为898个,每个水体平均损失数量为(1.87±0.27)个,总损失率为58.44%.研究表明:仅水深(P0.05)显著影响中国林蛙产卵数量;中国林蛙在道路两侧产卵对繁殖地水深60 cm具有一定选择性;相对潮湿度(P0.05)显著影响中国林蛙产卵损失率;相对潮湿度中半干旱类型对卵损失影响最大.     

Net carbon dioxide losses of northern ecosystems in response to autumn warming

The carbon balance of terrestrial ecosystems is particularly sensitive to climatic changes in autumn and spring, with spring and autumn temperatures over northern latitudes having risen by about 1.1 degrees C and 0.8 degrees C, respectively, over the past two decades. A simultaneous greening trend has also been observed, characterized by a longer growing season and greater photosynthetic activity. These observations have led to speculation that spring and autumn warming could enhance carbon sequestration and extend the period of net carbon uptake in the future. Here we analyse interannual variations in atmospheric carbon dioxide concentration data and ecosystem carbon dioxide fluxes. We find that atmospheric records from the past 20 years show a trend towards an earlier autumn-to-winter carbon dioxide build-up, suggesting a shorter net carbon uptake period. This trend cannot be explained by changes in atmospheric transport alone and, together with the ecosystem flux data, suggest increasing carbon losses in autumn. We use a process-based terrestrial biosphere model and satellite vegetation greenness index observations to investigate further the observed seasonal response of northern ecosystems to autumnal warming. We find that both photosynthesis and respiration increase during autumn warming, but the increase in respiration is greater. In contrast, warming increases photosynthesis more than respiration in spring. Our simulations and observations indicate that northern terrestrial ecosystems may currently lose carbon dioxide in response to autumn warming, with a sensitivity of about 0.2 PgC degrees C(-1), offsetting 90% of the increased carbon dioxide uptake during spring. If future autumn warming occurs at a faster rate than in spring, the ability of northern ecosystems to sequester carbon may be diminished earlier than previously suggested.     

柱塞马达低速稳定性的研究

本文针对柱塞马达低速稳定性问题进行了理论分析和实验研究,在大量实验的基础上提出了“马达最低稳定转速限制于马达系统临界点”的新观点。理论上用阻尼比近似零的状态所确定的临界点同对轴向及径向柱塞马达所做实验的结果基本一致。     

10kV配电线路无功补偿投切方式的比较分析

以10kV配电线路为研究背景,通过比较国内几种主流线路无功补偿投切方式,进行了投切方式对线路补偿的补偿容量和补偿位置影响的理论分析,并对投切方式对电压损失率与功率损失的影响进行了实例计算.结果表明,在10kV配电线路中,采取根据电压情况进行投切控制的方式更有利于提高功率因数、降低电压损失率.     

国内外信息产业的简况和比较分析

根据1995－1997年的最新统计资料,从比较学的角度分别在通讯业、计算机业、数据库业、信息服务业等四个方面对中国与美、日、法、德、英、印度等国家的信息产业进行了对比分析;不仅报道了当前中国信息产业的重大成应,而且找出了与国外先进水平的差距,提出了缩小差距的措施。