重大事件对城市发展影响研究综述

重大事件对城市在促进当地社会经济发展,提高举办城市的知名度方面具有重要影响。具体地体现在以下八个层面：城市整体发展、城市空间、城市规划和建筑设计、城市经济社会发展、城市生活、城市公共管理、提升城市形象与城市国际化。     

尺度目标的频域核回归跟踪研究

提出了一种基于频域核回归模型的尺度目标跟踪算法。该算法将时域相关滤波转换为频域的线性回归问题,构建一个包含似然项和先验项的代价损失函数,当似然项和先验项选取不同的分布函数,获得不同约束条件下的跟踪模型;通过核函数用来适应目标在跟踪过程的尺度变化。在初始帧中,通过手动标注目标初始状态,获得目标样本及其标记,利用核回归得到目标的频域模板;在跟踪过程中,利用循环卷积定理,将时域相关运算转换为频域乘积运算,快速计算候选样本的响应,得到目标在当前帧的估计;利用估计结果更新目标频域模板,同时在线更新核函数,适应目标尺度变化。实验分析表明,文中算法能够实时地跟踪目标,适应目标外观和尺度的变化,获得较好的跟踪效果。     

基于MRF的高分辨率SAR图像道路网自动提取

各种干扰的存在使得高分辨率合成孔径雷达(synthetic aperture radar,SAR)图像道路网的提取变得异常困难。马尔可夫随机场(Markov random field, MRF)模型能够充分利用道路图像的上下文特征以及先验知识,在道路网提取中得到广泛应用,但存在求解过程偏慢及参数设置偏多问题。首先根据道路空间几何特征关系对提取出的线基元进行预连接,以此减少虚假连接给MRF迭代求解带来的运算量;然后建立MRF道路网改进模型对道路网进行快速标记。使用1m机载高分辨率SAR图像进行实验,结果验证了该方法的有效性。     

双向向量值小波包

本文以向量值小波的基本理论和概念为基础,给出整数伸缩的双向向量值正交小波与双向向量值小波包的概念,以及向量值尺度函数与小波函数正交条件和稳定条件,得到正交的双向向量值小波包,并得到双向向量值小波包的性质和结论.     

Reversal of pathological pain through specific spinal GABAA receptor subtypes

Inflammatory diseases and neuropathic insults are frequently accompanied by severe and debilitating pain, which can become chronic and often unresponsive to conventional analgesic treatment. A loss of synaptic inhibition in the spinal dorsal horn is considered to contribute significantly to this pain pathology. Facilitation of spinal gamma-aminobutyric acid (GABA)ergic neurotransmission through modulation of GABA(A) receptors should be able to compensate for this loss. With the use of GABA(A)-receptor point-mutated knock-in mice in which specific GABA(A) receptor subtypes have been selectively rendered insensitive to benzodiazepine-site ligands, we show here that pronounced analgesia can be achieved by specifically targeting spinal GABA(A) receptors containing the alpha2 and/or alpha3 subunits. We show that their selective activation by the non-sedative ('alpha1-sparing') benzodiazepine-site ligand L-838,417 (ref. 13) is highly effective against inflammatory and neuropathic pain yet devoid of unwanted sedation, motor impairment and tolerance development. L-838,417 not only diminished the nociceptive input to the brain but also reduced the activity of brain areas related to the associative-emotional components of pain, as shown by functional magnetic resonance imaging in rats. These results provide a rational basis for the development of subtype-selective GABAergic drugs for the treatment of chronic pain, which is often refractory to classical analgesics.     

一类次二次Hamilton系统的次调和解的存在性

运用临界点理论中的极小极大方法得到一类次二次Hamilton系统的次调和解的存在性定理.     

Evidence for cooperative interactions in potassium channel gating.

Cloning and expression of voltage-activated potassium ion-channel complementary DNAs has confirmed that these channels are composed of four identical subunits, each containing a voltage sensor. It has been generally accepted that the voltage sensors must reach a permissive state through one or more conformational ('gating') transitions before the channel can open. To test whether each subunit gates independently, we have constructed cDNAs encoding four subunits on a single polypeptide chain, enabling us to specify the subunit stoichiometry. The gating of heterotetramers made up from combinations of subunits with different gating phenotypes strongly suggests that individual subunits gate cooperatively, rather than independently. Nonindependent subunit gating is consistent with measurements of the kinetics of K(+)-channel gating currents and in line with the widespread subunit cooperativity observed in other multisubunit proteins.     

Nitrogenase activity in a transfilter culture of rhizobia with a non-leguminous plant callus culture: Transfer of fixed15N2 from bacteria toPortulaca callus

Summary A transfilter culture of the non-leguminous plantPortulaca grandiflora var. JR andRhizobium sp. cowpea 32H1 was established. Using¹⁵N₂-analysis we demonstrated that¹⁵N-containing substances produced by the bacteria passed through the membrane and¹⁵N was enriched in the plant cells.Acknowledgment. The authors wish to express their gratitude to Prof. H. Marschner and Dr G. Hentschel for the determination of the nitrogen-content of our samples by the Dumasmethod and for advice on the optic emission method. Drs J. Burton, Milwaukee, Wisc., and Tjepkema, Oregon State University, are thanked for generous gifts ofRhizobium sp. cowpea 32H1. This work was supported by the DFG.     

光明山球粒陨石宇宙射线暴露年龄及气体保存年龄

光明山球粒陨石稀有气体同位素分析结果表明，宇宙成因核素３Ｈｅ，２１Ｎｅ及３８Ａｒ的宇宙射线暴露年龄分别为 ６５， ８０和 ６５ Ｍａ，平均为 ７０ Ｍａ，这是目前高铁普通球粒陨石（Ｈ群球粒陨石）中暴露年龄最高的陨石； Ｋ－Ａｒ及 Ｕ， Ｔｈ－４Ｈｅ气体保存年龄分别为（４２３０± １００）和（３３００± ６０） Ｍａ．宇宙成因３Ｈｅ暴露年龄小于２１Ｎｅ年龄，放射性成因 ４Ｈｅ保存年龄小于４０Ａｒ年龄，表明该陨石在碰撞破裂脱离母体后 ７０ Ｍａ的暴露期间，可能由于小的近日距轨道受到太阳加热，导致３Ｈｅ和４Ｈｅ的同步丢失．     

对我国农民工融入城市问题的探讨

在构建社会主义和谐社会的大背景下,解决农民工融入城市问题是一项长期而艰巨的任务,需要全社会的共同努力.首先,应消除制度障碍,保障农民工的合法权益；其次,要消除偏见和歧视,改善农民工融入城市的大环境；再次,加强对农民工的教育培训,提高其融入城市的能力.