A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation

The dwarf planet Eris is a trans-Neptunian object with an orbital eccentricity of 0.44, an inclination of 44 degrees and a surface composition very similar to that of Pluto. It resides at present at 95.7 astronomical units (1?AU is the Earth-Sun distance) from Earth, near its aphelion and more than three times farther than Pluto. Owing to this great distance, measuring its size or detecting a putative atmosphere is difficult. Here we report the observation of a multi-chord stellar occultation by Eris on 6 November 2010 UT. The event is consistent with a spherical shape for Eris, with radius 1,163?±?6?kilometres, density 2.52?±?0.05 grams per cm(3) and a high visible geometric albedo, Pv = 0.96(+0.09)(-0.04). No nitrogen, argon or methane atmospheres are detected with surface pressure larger than ～1?nanobar, about 10,000 times more tenuous than Pluto's present atmosphere. As Pluto's radius is estimated to be between 1,150 and 1,200 kilometres, Eris appears as a Pluto twin, with a bright surface possibly caused by a collapsed atmosphere, owing to its cold environment. We anticipate that this atmosphere may periodically sublimate as Eris approaches its perihelion, at 37.8 astronomical units from the Sun.     

国学的术语规范问题

国学的术语规范指的是国学所属各学科的术语规范。国学术语的规范既是术语学和国学的研究对象,也是语言规划的重要内容,同时它还是建设有中国特色术语学的重要组成部分。文章从国学术语的概念划分、科学定义、术语定名和译介等方面对国学的术语规范问题作了系统阐述。     

人工关节材料及其表面改性研究进展

人工关节是替代病变或损伤关节的植入性假体,除了应满足生物相容性要求外,必须具备足够的抗磨损能力。本文综述了目前使用的不同人工关节材料的性能,以及为提高抗磨损能力而对各种材料进行改性处理的新方法,提出在人工关节表面加工微纳结构来提高其抗磨损性能和生物相容性的新思路。     

Inhibition of endogenous phosphodiesterase 7 promotes oligodendrocyte precursor differentiation and survival

During the development of the central nervous system (CNS), oligodendrocyte precursors (OPCs) are generated in specific sites within the neural tube and then migrate to colonize the entire CNS, where they differentiate into myelin-forming oligodendrocytes. Demyelinating diseases such as multiple sclerosis (MS) are characterized by the death of these cells. The CNS reacts to demyelination and by promoting spontaneous remyelination, an effect mediated by endogenous OPCs, cells that represent approximately 5–7 % of the cells in the adult brain. Numerous factors influence oligodendrogliogenesis and oligodendrocyte differentiation, including morphogens, growth factors, chemotropic molecules, extracellular matrix proteins, and intracellular cAMP levels. Here, we show that during development and in early adulthood, OPCs in the murine cerebral cortex contain phosphodiesterase-7 (PDE7) that metabolizes cAMP. We investigated the effects of different PDE7 inhibitors (the well-known BRL-50481 and two new ones, TC3.6 and VP1.15) on OPC proliferation, survival, and differentiation. While none of the PDE7 inhibitors analyzed altered OPC proliferation, TC3.6 and VP1.15 enhanced OPC survival and differentiation, processes in which ERK intracellular signaling played a key role. PDE7 expression was also observed in OPCs isolated from adult human brains and the differentiation of these OPCs into more mature oligodendroglial phenotypes was accelerated by treatment with both new PDE7 inhibitors. These findings reveal new roles for PDE7 in regulating OPC survival and differentiation during brain development and in adulthood, and they may further our understanding of myelination and facilitate the development of therapeutic remyelination strategies for the treatment of MS.     

基于小波与BP神经网络的太阳黑子时间序列分析预测

太阳黑子年平均数序列是典型的非线性、复杂时间序列.本文利用小波变换,将太阳黑子年平均数序列进行分解重构,对信号的周期特性进行分析,然后采用BP神经网络对重构信号进行预测,建立太阳黑子年平均数的预测序列.结果表明,该模型具有较高的预测精度.     

西安市住宅价格波动状况及政策建议

研究西安市住宅价格的波动特性及其产生原因,建立系统动力学中的因果回路图模型,分析住宅价格的因果反馈环.得出西安市住宅价格近年来处于上涨态势,但与一线城市和其它部分二线城市住宅价格波动幅度相比,波动幅度小并趋于稳定上升状态.为此提出,政府应坚持房地产调控不动摇,根据不同的需求层次合理地开发住宅产业,引导住宅需求的梯度消费,同时加强保障性安居工程建设.     

山西省R＆D经费投入状况分析

通过对山西省R&D经费投入状况的分析,指出了其不足与存在的问题,并进一步提出应加大山西省R&D经费投入力度,使R&D活动真正成为促进山西省经济发展的主要动力。     

浅谈居住小区规划技术标准的修改

针对当前《城市居住区规划设计规划》中部分指标老化给居住小区规划带来的负面影响,分别分析了城市居住小区户均人口下降、人均居住用地指标增大、机动车交通迅速增长、城市社会人口年龄结构变化以及人们日常生活需求的变化对小区规划产生的影响,指出应相应调整《规范》中关于小区规模、道路与停车设施、配套公共设施及小区绿地的规划设计指标,并应进一步完善指标体系,从而使小区规划更科学合理。     

Identification of common variants influencing risk of the tauopathy progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is a movement disorder with prominent tau neuropathology. Brain diseases with abnormal tau deposits are called tauopathies, the most common of which is Alzheimer's disease. Environmental causes of tauopathies include repetitive head trauma associated with some sports. To identify common genetic variation contributing to risk for tauopathies, we carried out a genome-wide association study of 1,114 individuals with PSP (cases) and 3,247 controls (stage 1) followed by a second stage in which we genotyped 1,051 cases and 3,560 controls for the stage 1 SNPs that yielded P ≤ 10(-3). We found significant previously unidentified signals (P < 5 × 10(-8)) associated with PSP risk at STX6, EIF2AK3 and MOBP. We confirmed two independent variants in MAPT affecting risk for PSP, one of which influences MAPT brain expression. The genes implicated encode proteins for vesicle-membrane fusion at the Golgi-endosomal interface, for the endoplasmic reticulum unfolded protein response and for a myelin structural component.     

凉水自然保护区森林群落中蕨类植物多样性的调查

首次报道了凉水自然保护区森林群落中蕨类植物多样性指数的基础数据，并进行了初步分析。