A fast and effective method to perform paternity testing for Wolong giant pandas

Captive populations provide a precious genetic resource for endangered animals and a source of individuals for reintroduction to depleted habitats. Therefore, accuracy in determining paternity is of vital importance for managing captive populations and in selecting representative individuals of known genetic characteristics for release. In this study, we established a fast and effective method to conduct paternity testing for captive giant pandas in the Wolong population. This technique uses two highly poly...     

Magnetic fields at the solar wind termination shock

A transition between the supersonic solar wind and the subsonic heliosheath was observed by Voyager 1, but the expected termination shock was not seen owing to a gap in the telemetry. Here we report observations of the magnetic field structure and dynamics of the termination shock, made by Voyager 2 on 31 August-1 September 2007 at a distance of 83.7 au from the Sun (1 au is the Earth-Sun distance). A single crossing of the shock was expected, with a boundary that was stable on a timescale of several days. But the data reveal a complex, rippled, quasi-perpendicular supercritical magnetohydrodynamic shock of moderate strength undergoing reformation on a scale of a few hours. The observed structure suggests the importance of ionized interstellar atoms ('pickup protons') at the shock.     

The first hominin of Europe

The earliest hominin occupation of Europe is one of the most debated topics in palaeoanthropology. However, the purportedly oldest of the Early Pleistocene sites in Eurasia lack precise age control and contain stone tools rather than human fossil remains. Here we report the discovery of a human mandible associated with an assemblage of Mode 1 lithic tools and faunal remains bearing traces of hominin processing, in stratigraphic level TE9 at the site of the Sima del Elefante, Atapuerca, Spain. Level TE9 has been dated to the Early Pleistocene (approximately 1.2-1.1 Myr), based on a combination of palaeomagnetism, cosmogenic nuclides and biostratigraphy. The Sima del Elefante site thus emerges as the oldest, most accurately dated record of human occupation in Europe, to our knowledge. The study of the human mandible suggests that the first settlement of Western Europe could be related to an early demographic expansion out of Africa. The new evidence, with previous findings in other Atapuerca sites (level TD6 from Gran Dolina), also suggests that a speciation event occurred in this extreme area of the Eurasian continent during the Early Pleistocene, initiating the hominin lineage represented by the TE9 and TD6 hominins.     

Molecular evolution of connective tissue growth factor in Cyprinidae （Teleostei： Cypriniformes）

Connective tissue growth factor （CTGF） plays an important role in regulation of cell growth, differentiation, apoptosis and individual development in animals. The study of sequences variation and molecular evolution of CTGF gene across various species of the cyprinid could be helpful for understanding of speciation and gene divergence in this kind of fish. In this study, 19 novel sequences of CTGF gene were obtained from the representative species of the family Cyprinidae using PCR amplification, cloning and sequencing. Phylogenetic relationships of Cyprinidae were reconstructed by neighbor-joining （NJ）, maximum parsimony （MP）, maximum likelihood （ML） and Bayesian method. Oryzias latipes from the family Cyprinodontidae was assigned to be the outgroup taxon. Leuciscini and Barbini were clustered into the monophyletic lineages, respectively, with the high nodal supports. The estimation of the ratio of non-synonymous to synonymous substitution （dN/dS） for the various branches indicated that there stood the different evolution rates between the Leuciscini and the Barbini. With the ratio of dN/dS of the Leuciscini being lower than that of the Barbini, species within the Barbini were demonstrated to be subjected to the relatively less selection pressure and under the relaxable evolution background. A 6 bp indel （insertion/deletion） was found at the 5＇ end of CTGF gene of Cyprinidae, and this 6 bp deletion only appeared in the Leuciscini, which is a typical characteristic of the Leuciscini and provides evidence for the monophylogeny of the Leuciscini. For the amino acid sequences of CTGF protein, the most variations and indels were distributed in the signal region and IGFBP region of this protein, implying that these variations were correlated with the regulation of the CTGF gene expression and protein activity.     

A Cretaceous terrestrial snake with robust hindlimbs and a sacrum

It has commonly been thought that snakes underwent progressive loss of their limbs by gradual diminution of their use. However, recent developmental and palaeontological discoveries suggest a more complex scenario of limb reduction, still poorly documented in the fossil record. Here we report a fossil snake with a sacrum supporting a pelvic girdle and robust, functional legs outside the ribcage. The new fossil, from the Upper Cretaceous period of Patagonia, fills an important gap in the evolutionary progression towards limblessness because other known fossil snakes with developed hindlimbs, the marine Haasiophis, Pachyrhachis and Eupodophis, lack a sacral region. Phylogenetic analysis shows that the new fossil is the most primitive (basal) snake known and that all other limbed fossil snakes are closer to the more advanced macrostomatan snakes, a group including boas, pythons and colubroids. The new fossil retains several features associated with a subterranean or surface dwelling life that are also present in primitive extant snake lineages, supporting the hypothesis of a terrestrial rather than marine origin of snakes.     

基于逻辑选择脉冲时滞动力系统的稳定性分析

为了使动力系统在稳定性分析上更具有一般化,能更加精确实际地刻画自然现象;针对具有逻辑选择脉冲效应的时滞动力系统,提出此系统的全局指数稳定性分析问题,可在一定程度上推广一般脉冲时滞动力系统的稳定性分析;通过引入具有逻辑选择脉冲效应的时滞非线性动力系统,并利用半张量积将该动力系统中的逻辑函数转换为代数状态空间表示,再建立脉冲型 Halanay 微分不等式来估计该动力系统中线性系统部分的 Cauchy 矩阵; 基于此,对向量和函数给出了4个假设条件,得到在逻辑选择脉冲控制下的非线性时滞系统的零解全局指数稳定性判定依据,且证明了此动力系统的指数收敛率为 λ-η。     

基于数据素养的数据库系列课程教学改革研究

新工科背景下高等工程教育改革进入新阶段,数据素养日显重要。传统的数据库课程体系不够完善,培养意识不够明确。基于此,根据新工科背景下应用型本科人才培养目标,提出结合数据素养理念进行教学改革的思路和具体实践措施。根据“二线并行、逐层递进”的模式重新规划课程体系结构,加大实践教学的比重,形成以数据素养指标体系和评价体系来指导教学的方法,并完善课程教学资源,设计多样性实践考核方式,有效地促进学生学习的积极性,实现数据素养与数据库系列课程相融合的教学改革新模式,为提升应用型本科课程教学质量提供借鉴和方法。     

基于翻转课堂的大学计算机基础课程教学模式研究

大学计算机基础课程是一门重要的基础课程,但因当前高等院校存在生源复杂、学生水平参差不齐等问题,实际教学效果不尽如人意。分析了当前大学计算机基础课程改革面临的新挑战,探讨了基于翻转课堂的教学新模式,使学生在通过自主学习完成对知识的深度掌握。通过问卷调查和对比研究,证明该模式在一定程度上提高了学生学习兴趣,有利于知识的吸收,提高了教学质量,获得了较好的教学效果。