Caffeine as a psychomotor stimulant: mechanism of action

The popularity of caffeine as a psychoactive drug is due to its stimulant properties, which depend on its ability to reduce adenosine transmission in the brain. Adenosine A₁ and A_2A receptors are expressed in the basal ganglia, a group of structures involved in various aspects of motor control. Caffeine acts as an antagonist to both types of receptors. Increasing evidence indicates that the psychomotor stimulant effect of caffeine is generated by affecting a particular group of projection neurons located in the striatum, the main receiving area of the basal ganglia. These cells express high levels of adenosine A_2A receptors, which are involved in various intracellular processes, including the expression of immediate early genes and regulation of the dopamine- and cyclic AMP-regulated 32-kDa phosphoprotein DARPP-32. The present review focuses on the effects of caffeine on striatal signal transduction and on their involvement in caffeine-mediated motor stimulation.Received 8 July 2003; received after revision 7 September 2003; accepted 6 October 2003     

七绝、文人竹枝词与客家山歌

七绝,本为来自民间的七言诗,经永明体而为近体诗之一种诗体;竹枝词,本为巴渝民歌,自刘禹锡以降．历代文人多有仿作,所仿作者为文人竹枝词;而客家山歌,则是自明清客家民系形成以来,至今犹传承于客地的鲜活民歌。从这三种诗歌中,可发现雅俗文学之间的交融、碰撞而嬗变的文学雅俗互动的有趣轨迹。     

与时俱进,继往开来:"三个代表"的理论品格

生产力观上的与时俱进、继往开来,文化观上的与时俱进、继往开来和人民利益观上的与时俱进、继往开来,是“三个代表”的理论品格。学习贯彻“三个代表”思想时,一定要把握其对马克思主义、毛泽东思想、邓小平理论既有继承又有发展,既有坚持又有创新的辩证关系。     

加强党的作风建设,努力探索党委领导下的校长负责制运行模式

党委领导下的校长负责制是我国现阶段高等学校的领导体制,新升格的高职应加强党的作风建 设,从领导班子建设、学风建设、制度建设、组织建设、民主建设和通过抓大事抓发展等工作树立党委威 信等方面入手,努力探索切合高职院实际的党委领导下的校长负责制的运行模式。     

Measuring radial Young’s modulus of DNA by tapping mode AFM

Based on tapping mode AFM imaging, a method was demonstrated to evaluate compression elasticity of single double-stranded DNA （dsDNA） molecules in the force region. With images under ambient conditions, Young＇s moduli of dsDNA in compression were calculated. Results demonstrated that Young＇s moduli of dsDNA can be simply deduced according to the proposed model. The method can also be used to evaluate the compression elasticity of similar soft nanomaterials.     

额田王咏秋风歌之语象溯源

古代中日两国吟咏爱情的诗歌中，“秋风”一词时有所见。从日本最早的古典和歌大成《万叶集》中所记载的、由女歌人额田王所咪的“思近江天皇咏秋风歌”可知，它与中国六朝闺怨诗既有联系又有区别，“秋风”语象在当时的中日诗歌中具有不同的意蕴。     

Klein-Weyl's program and the ontology of gauge and quantum systems

We distinguish two orientations in Weyl's analysis of the fundamental role played by the notion of symmetry in physics, namely an orientation inspired by Klein's Erlangen program and a phenomenological-transcendental orientation. By privileging the former to the detriment of the latter, we sketch a group(oid)-theoretical program—that we call the Klein-Weyl program—for the interpretation of both gauge theories and quantum mechanics in a single conceptual framework. This program is based on Weyl's notion of a “structure-endowed entity” equipped with a “group of automorphisms”. First, we analyze what Weyl calls the “problem of relativity” in the frameworks provided by special relativity, general relativity, and Yang-Mills theories. We argue that both general relativity and Yang-Mills theories can be understood in terms of a localization of Klein's Erlangen program: while the latter describes the group-theoretical automorphisms of a single structure (such as homogenous geometries), local gauge symmetries and the corresponding gauge fields (Ehresmann connections) can be naturally understood in terms of the groupoid-theoretical isomorphisms in a family of identical structures. Second, we argue that quantum mechanics can be understood in terms of a linearization of Klein's Erlangen program. This stance leads us to an interpretation of the fact that quantum numbers are “indices characterizing representations of groups” ((Weyl, 1931a), p.xxi) in terms of a correspondence between the ontological categories of identity and determinateness.     

随机变量序列几乎处处收敛的几个等价命题

由随机变量序列几乎处处收敛可推出其依概率收敛，进而可推出其依分布收敛，可见判别几乎处处收敛的重要性．给出了它的几个等价命题，同时还证明了独立随机变量和序列几乎处处收敛等价于依概率收敛，亦等价于依分布收敛．     

明清时期高密单氏家族文化成因

高密单氏是明清时期著名的文化世家。明末,这个家族以科举起家,此后200余年保持门第不坠,涌现了一大批文化精英,他们在诗歌、古文、经学及书法等领域取得了突出成就,促进了明清时期齐鲁文化的繁荣。高密单氏家族独特而出色的家族文化的形成,有其深层原因。     

基于模糊病态性识别的自适应仿真算法

在已有病态性识别方法的基础上引入模糊集合理论，构造准确性更高的识别方法，并将它用在自适应仿真算法中。