A unified C-band and Ku-band geophysical model function determined by neural network approach

The geophysical model function （GMF） describes the relationship between backscattering and sea surface wind, so that wind vec- tors can be retrieved from backscattering measurement. The GMF plays an important role in ocean wind vector retrievals, its performance will directly influence the accuracy of the retrieved wind vector. Neural network （NN） approach is used to develop a unified GMF for C-band and Ku-band （NN-GMF）. Empirical GMF CMOIM and QSCAT-1 are used to generate the simulated training data-set, and Gaussian noise at a signal noise ratio of 30 dB is added to the data-set to simulate the noise in the backscat- tering measurement. The NN-GMF employs radio frequency as an additional parameter, so it can be applied for both C-band and Ku-band. Analyses show that the %predicted by the NN-GMF is comparable with the σpredicted by CMOIM and QSCAT-1. Also the wind vectors retrieved from the NN-GMF and empirical GMF CMOIM and QSCAT-1 are comparable, indicating that the NN-GMF is as effective as the empirical GMF, and has the advantages of the universal form.     

进化论与生命进化的9次巨大飞跃

<正>1859年,查尔斯·罗伯特·达尔文在完成环球考察23年后,发表了震惊世界影响古今的鸿篇巨著《物种起源》,提出了进化论的思想。进化论被誉为人类历史上第二次重大科学突破,它证明了所有的生物都不是上帝创造,而是自身基因变异或突变,在自然选择的作用下,优胜劣汰,适应环境变化的基因变异遗传下来,并不断进化来的。基因变异或突变是随机的,而自然选择是适应性变异的结果,并不总是由     

http://www.sciencedirect.com/science/article/pii/S167498711100079X

Lower Paleozoic rocks exposed in various regions of Egypt (south central Sinai, north Eastern Desert and southwest Western Desert), in addition to occurring in the subsurface such as north Western Desert and the Gulf of Suez. The Lower Paleozoic rocks in Egypt include surface and subsurface rock units of formational status. The surface rock units are the Taba, Araba and Naqus formations. The subsurface rock units include the Shifa, Kohla and Basur formations. The Infracambrian Taba Formation has been discovered recently in the outcrops of the south eastern Sinai in the Taba-Ras El-Naqab area. It is missing and/or not recognized in the subsurface. The Taba Formation consists mainly of reddish brown, unfossiliferous gravelly fine-to medium-grained sandstones cemented by kaolinite and have subordinate beds of paleosols. The Cambrian Araba Formation and its subsurface equivalent (the Shifa Formation) are essentially composed of reddish brown, fine-grained laminated sandstone and siltstone with abundant Skolithos and Cruziana sp. In contrast, the Ordovician-Silurian Naqus Formation and its subsurface equivalents (Kohla Formation and Basur Formation) are mainly composed of white, unfossiliferous, cross-bedded, medium- to coarse-grained sandstones with haphazardly distributed pebbles and cobbles. Sedimentological analysis indicates that the Araba Formation and its equivalents were deposited in a marginal-marine environment, whereas the Naqus Formation and its equivalents were laid down in a fluvio-glacial environment. Integrated stratigraphic and sedimentological studies of the Lower Paleozoic rocks permit reconstruction of the paleogeography of Egypt at that time. Egypt has been largely controlled since the Cambrian by the pre-existing structural framework of the pre-Phanerozoic basement rocks inherited from the Late Proterozoic Pan-African event. Additionally, sedimentation processes were controlled during Cambro-Ordovician times by tectonic movements, whereas glacio-eustatic control predominated during the Late Ordovician-Silurian Period. These studies suggest that most areas of Egypt were exposed lands with episodically transgression by epicontinental seas related to the paleo-Tethys. These lands formed a part of a stable subsiding shelf at the northern Gondwana margin.     

鱼类生长激素的异源表达、应用及安全性评价

鱼类生长激素对鱼的生长发育起着重要的调节作用,能促进鱼体快速生长,提高饵料转化率,在水产养殖业中具有重大应用价值。转生长激素基因鱼具有快速生长效应,可以缩短养殖周期,降低养殖成本和风险。鱼类生长激素基因异源表达体系的建立和发展,使获得大量廉价的鱼类生长激素产品成为可能,为鱼类养殖业新型饵料添加剂的研制开辟了新的途径。本文综述了转生长激素基因鱼和鱼类生长激素基因的异源表达两方面的研究及其安全性评价。     

地名地址基因的网页文本地名地址提取算法

针对网页文本蕴含着丰富的地名地址空间信息,但因其描述的随机性、多样性,导致信息很难被快速、准确地识别出来的问题。该文在分析网页文本中地名地址组成特点的基础上,考虑地名地址的事件属性,提出了一种基于"地名地址基因"的信息提取方法,依据事件相关度、地名地址的字符长度等提取因子建立提取规则树获取目标地名地址。实际数据测试表明该方法在地名地址提取上更具针对性,提高了效率和准确率。     

水体细菌碱性磷酸酶及其编码基因研究进展

水体溶解性反应磷是浮游植物可直接利用的主要磷营养形式,细菌碱性磷酸酶催化的有机磷矿化过程则是维持溶解性反应磷供给的重要途径.通过总结细菌碱性磷酸酶的种类与分布特征,发现主要包括Pho A、Pho X和Pho D 3种类型细菌碱性磷酸酶,其中超过50%的Pho X分布于细菌细胞的外部环境,对溶解性反应磷的循环再生尤为重要.综述水体产碱性磷酸酶细菌群落组成的研究进展,以及影响编码基因表达的环境因素,对比分析产碱性磷酸酶细菌群落鉴定方法的特点及发展趋势.细菌碱性磷酸酶编码基因的研究多关注寡营养海洋生态系统,对于同样存在磷限制问题的富营养化湖泊生态系统鲜有涉及,而构建针对典型富营养化湖泊生态系统的细菌宏基因组数据库,则可为建立淡水生态系统细菌碱性磷酸酶及其编码基因的研究方法奠定基础,有助于认识湖泊水华频发的微生物学驱动机制.     

5个湖泊河川沙塘鳢(Odontobutis potamophila)种群线粒体细胞色素b基因的遗传变异分析

通过对5个湖泊的河川沙塘鳢种群的线粒体DNA细胞色素b基因进行PCR扩增、测序,获得1141 bp的序列全长.序列分析显示,cyt b基因序列中A+T含量(55.8%)略高于G+C含量(44.2%),共检测到806个多态位点,115个样本得到87个单倍型,平均单倍型多样性为0.969±0.012,核苷酸多样性为0.20081±0.00742,遗传多样性表现高度多样性.太湖种群与大纵湖种群间的遗传距离最近,为0.137,巢湖种群和大纵湖种群之间遗传距离最远,为0.424.分子方差分析表明,群体间遗传分化系数Fst为0.531,变异来自群体内及群体间.cyt b基因序列构建的UPGMA系统进化树显示,5个种群分化成不同的分支系谱,种群间存在的基因交流较少.     

中国传统聚落景观区划及景观基因识别要素研究

传统聚落景观区划是一项理论性和实践性都很强的工作,是文化景观区划研究的重要课题之一。基于中国传统聚落景观本身存在的地域性、系统性、稳定性、发展性、一致性、典型性和协调性等特点,本方案以传统聚落景观“意象”(Image) 的内部相似性为前提,以相对一致性原则作为景观区域划分的主导性原则,综合考虑其他原则,如环境制约性原则、文化主导性原则、地域完整性原则、相对一致性原则、面的覆盖性原则、层次性原则和综合性原则等,将全国聚落景观初步划分为3 个大尺度的景观大区、14 个景观区和76 个景观亚区。以往关于文化区的识别,主要从文化特征的角度进行的;关于传统聚落景观区的识别,主要是从景观基因的角度进行的。区域景观基因成为判断传统聚落景观区的核心要素。通常情况下,传统聚落景观基因的判别,可以重点从心理要素、生态要素、美学要素、环境要素、文化要素、时序要素等6 个方面入手。     

基于形态学特征和DNA条形码对中国沿海银口天竺鲷属(Jaydia)分类研究

本研究针对中国沿海银口天竺鲷属鱼类分类鉴定不清晰,同种异名多,种类误鉴等分类问题,结合形态特征比较与DNA条形码技术对其分类鉴定问题进行梳理。2014—2019年间于南海北部沿海采集101尾银口天竺鲷属鱼类标本,经形态学特征鉴定为:横带银口天竺鲷Jaydia striata(Smith & Radcliffe, 1912),特征为体侧有7—11褐色宽横带,腹鳍、臀鳍浅灰色;印度洋银口天竺鲷J.striatodes(Gon,1997),特征为体侧有7—11褐色宽横带,臀鳍后缘黑色;白边银口天竺鲷J.novaeguineae(Valenciennes,1832),特征为臀鳍、尾鳍最下缘为白边;黑边银口天竺鲷J.truncata(Bleeker,1855)特征为第二背鳍、臀鳍中部有一平行基底的黑色带,尾鳍后缘黑色带略宽;史密斯银口天竺鲷J.smithi Kotthaus,1970,特征为第二背鳍中部有一平行基底的黑色纵带,尾鳍后缘黑色带略细;斑鳍银口天竺鲷J.carinatus(Cuvier,1828),特征为第二背鳍最末软条基底有一大黑斑;黑鳃银口天竺鲷J.poeciloptera...     

基于转录组测序技术对调控毕加索小丑鱼（Picasso clownfish）白化体征关键基因的研究

毕加索小丑鱼（Picasso clownfish）因其皮肤中的白色斑块分布杂乱抽象而得名,同时也由于其白色斑块的形成无规律性和稀缺性,属于名贵的小丑鱼,因此,解析毕加索小丑鱼的皮肤白斑形成机制,可以为毕加索小丑鱼的人工育种提供理论依据。在本研究中,我们对3种体色毕加索小丑鱼的背鳍和臀鳍之间的身体相同部位3种色块（黑色、黄色、白色）的皮肤进行进行了转录组测序。研究结果显示,与黄色和黑色皮肤组织相比,在白色皮肤组织中存在大量差异表达基因。其中与黑色素产生相关的信号通路（例如黑色素生成、Hedgehog信号通路和Wnt信号通路）中的基因在白色皮肤组织中呈下调表达趋势。进一步对3种颜色皮肤组织中参与黑色素生成途径的基因进行详细分析,发现上游调控基因（如ednrba和mitfa）表达量从黑色到黄色至白色皮肤组织中逐步下调,但下游参与黑色素合成的核心基因（包括tyr、tyrp1b和dct）则在白色皮肤组织中表达出现显著下调。最后,本研究通过荧光定量PCR验证了转录组数据的可靠性。本研究结果将为今后人为干扰基因表达从而达到调控小丑鱼体色提供理论依据。