In vivo enhancer analysis of human conserved non-coding sequences

Identifying the sequences that direct the spatial and temporal expression of genes and defining their function in vivo remains a significant challenge in the annotation of vertebrate genomes. One major obstacle is the lack of experimentally validated training sets. In this study, we made use of extreme evolutionary sequence conservation as a filter to identify putative gene regulatory elements, and characterized the in vivo enhancer activity of a large group of non-coding elements in the human genome that are conserved in human-pufferfish, Takifugu (Fugu) rubripes, or ultraconserved in human-mouse-rat. We tested 167 of these extremely conserved sequences in a transgenic mouse enhancer assay. Here we report that 45% of these sequences functioned reproducibly as tissue-specific enhancers of gene expression at embryonic day 11.5. While directing expression in a broad range of anatomical structures in the embryo, the majority of the 75 enhancers directed expression to various regions of the developing nervous system. We identified sequence signatures enriched in a subset of these elements that targeted forebrain expression, and used these features to rank all approximately 3,100 non-coding elements in the human genome that are conserved between human and Fugu. The testing of the top predictions in transgenic mice resulted in a threefold enrichment for sequences with forebrain enhancer activity. These data dramatically expand the catalogue of human gene enhancers that have been characterized in vivo, and illustrate the utility of such training sets for a variety of biological applications, including decoding the regulatory vocabulary of the human genome.     

Supercurrent reversal in quantum dots

When two superconductors are electrically connected by a weak link--such as a tunnel barrier--a zero-resistance supercurrent can flow. This supercurrent is carried by Cooper pairs of electrons with a combined charge of twice the elementary charge, e. The 2e charge quantum is clearly visible in the height of voltage steps in Josephson junctions under microwave irradiation, and in the magnetic flux periodicity of h/2e (where h is Planck's constant) in superconducting quantum interference devices. Here we study supercurrents through a quantum dot created in a semiconductor nanowire by local electrostatic gating. Owing to strong Coulomb interaction, electrons only tunnel one-by-one through the discrete energy levels of the quantum dot. This nevertheless can yield a supercurrent when subsequent tunnel events are coherent. These quantum coherent tunnelling processes can result in either a positive or a negative supercurrent, that is, in a normal or a pi-junction, respectively. We demonstrate that the supercurrent reverses sign by adding a single electron spin to the quantum dot. When excited states of the quantum dot are involved in transport, the supercurrent sign also depends on the character of the orbital wavefunctions.     

No signature of clear CO2 ice from the 'cryptic' regions in Mars' south seasonal polar cap

The seasonal polar ice caps of Mars are composed mainly of CO2 ice. A region of low (< 30%) albedo has been observed within the south seasonal cap during early to mid-spring. The low temperature of this 'cryptic region' has been attributed to a clear slab of nearly pure CO2 ice, with the low albedo resulting from absorption by the underlying surface. Here we report near-infrared imaging spectroscopy of the south seasonal cap. The deep and broad CO2 absorption bands that are expected in the near-infrared with a thick transparent slab of CO2 ice are not observed. Models of the observed spectra indicate that the low albedo results from extensive dust contamination close to the surface of a CO2 ice layer, which could be linked to atmospheric circulation patterns. The strength of the CO2 absorption increases after mid-spring, so part of the dust is either carried away or buried more deeply in the ice layer during the CO2 ice sublimation process.     

甘肃窑街侏罗纪Yuchoulepis szechuanensis Su的发现及地质学意义

对甘肃中侏罗统窑街组油页岩段中的四川渝州鱼化石进行了初步研究，认为该油页岩段的形成时代应为中侏罗世阿林期(Aalenian)——巴柔期(Bajocian)．并利用埋藏学和现代湖泊学的研究，结合含鱼化石上、下地层中生物类群的特点，推测了当时鱼群生活的环境及其死亡原因，论证了此期的气候特点为温暖潮湿性．     

华北落叶松鞘蛾生物学特性及防治技术研究

对华北落叶松鞘蛾在山西省的生活史及其生活习性作了介绍，并提出了综合防治措施。     

聋哑大学生思想政治教育方法途径初探

聋哑学生的教育是我国社会主义教育事业的一个组成部分。对高等特殊教育聋哑学生身心特点进行分析，得出对聋哑学生思想政治教育采取的教学方法，加强聋哑大学生的课外思想教育活动，把他们培养成德、智、体全面发展并具有良好心理素质的社会主义事业接班人和建设者。     

高寒地区混凝土防渗节水问题的探讨

渠道混凝土防渗节水工程是提高农田灌溉面积，减少水资源浪费的有效措施之一，文章提出了混凝土防渗节水设计的具体内容，包括混凝土水灰比的设计，不同砂粒的最佳搭配，骨料的最佳选择及最佳灰砂比的确定，以及根据裂缝，温度，湿度对混凝土的影响所应采取的相应防治措施。