994 resultados para Janninck, Conrad, 1650-1723


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The morphology of a novel poly(aryl ether ketone) [PEDEKmK] was investigated via polarizing optical microscopy (POM), TEM, DSC, SAXS and electron diffraction (ED). A distinct change in lamellar thickness, orientation, and spherulitic morphology was observed due to crystal melting and recrystallization. However, the crystal packing mode is found to be identical before and after the recrystallization process.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

[(Me4C2Cp2SmCl.MgCl2.3THF)THF]2 was prepared by the reaction of Me4C2Cp2MgCl2.4THF (Cp=C5H4, THF = tetrahydrofuran) with SmCl3 in THF. The crystals belong to triclinic space group P-1 with a 12.149(3), b 13.187(4), c 13.810(5) angstrom, alpha 117.23(2), beta 94.07(2), gamma 62.86(2)-degrees, V = 1723.9(1.0) angstrom3. In the molecular structure of the title compound there is a symmetrical centre and a quadrilateral formed by SM, Mg, Cl1, Cl2 atoms. Two centroids of the cyclopentadienyls, bridged by a tetramethylethano group form with three bridging chlorine atoms (Cl1, Cl2, Cl1a) a pseudo-trigonal bipyramid around Sm. Three oxygen atoms of THF and three chlorine atoMS (Cl1, Cl2, Cl3) constitute a distorted octahedron around Mg.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A field population of Ulva pseudocurvata Koeman et C. Hoek (hereafter termed Ulva) at Sylt Island (North Sea, Germany) exhibited biweekly peaks of gametophytic reproduction during the colder seasons and approximately weekly peaks during summer. The reproductive events lasted 1-5 d and were separated from each other by purely vegetative phases. Under constant conditions in the laboratory, a free-running rhythm was observed with reproductive peaks occurring approximately every 7 d. When artificial moonlight was provided every 4 weeks, fewer reproductive events occurred, and the reproductive rhythm became synchronized to the environmental artificial moonlight rhythm. In the laboratory, apical disks were entirely converted into reproductive tissue after 8 d cultivation, while almost all basal disks stayed vegetative, which prevented the entire loss of the vegetative thallus during reproductive events. Seasonal size reduction of the thallus occurred from late autumn onward and was determined to be controlled by a genuine photoperiodic response, since size reduction could be induced from May onward by experimental short-day (SD) treatment but was prevented in a long-day (LD) or night-break regime (NB). A daily fine-tuning occurred with gamete release early in the morning at the first sign of daylight, following an obligatory dark ("night") period of at least 1 h duration. No release took place if the overnight dark phase was replaced by continuous light. Blue, green, or red light all triggered gamete release after a dark phase at an irradiance of 0.1 mu mol photons . m(-2) .s(-1), while 0.001 mu mol photons . m(-2) . s(-1) was equivalent to a dark control.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

2005年6月,中法国际合作在西太平洋海域执行IMAGES XII-MD147 Micro Polo1航次科学考察时,由法国极地研究所R/V Marine Dufresne极地考察船利用Calypso重力取样器于冲绳海槽南部钻取了34.2米长MD05-2908柱状样。本文利用AMS14C测年数据建立了该孔的年代模型,对该孔的浮游有孔虫动物群落进行了分析,并利用FP-12E浮游有孔虫转换函数和Q型因子分析方法对该孔浮游有孔虫数据进行了研究,对全新世以来的黑潮流系演化和古环境记录进行了讨论。 结果表明,中晚全新世存在着5次洪水爆发期,洪水爆发期与当时温暖气候相对应,而高海平面对洪水的爆发也产生了影响。进入全新世以来的6790~4000a B.P.期间,黑潮流一直有稳步增强的趋势,黑潮流始终位于冲绳海槽内;4000~3000a B.P.期间,黑潮强度减弱或者发生明显东偏,冲淡水影响增强;3000a B.P.以后黑潮强度逐渐增强,1650~0a B.P.为中晚全新世以来黑潮活动最强的时期,在600a B.P.和140a B.P.左右存在低值,黑潮强度短暂减弱。普林虫低值事件在MD05-2908孔中有很好的体现,对该事件进行了进一步定年,其发生时间为3900~2800a B.P.,持续时间为1100a,该事件的发生可能与东亚冬季风加强有关。 冲绳海槽中晚全新世气候变化可以分为四个阶段: 6790~4800a B.P.低温阶段,4800~4100a B.P.高温阶段,4100~2400a B.P.低温阶段,2400~0a B.P.波动高温阶段。通过与中国及世界其它地方对比可以识别出6.3~5.9、5.5、4.6~4.2、3.6~3.0、2.9~2.4、1.3~1.0、0.5~0.1ka B.P.六个降温事件,为全新世气候波动在深海高分辨率沉积记录中的响应提供了有力支持。该孔SST频谱分析结果显示,存在着3008a、1061a这种千年尺度的周期,以及215a、123a、103~107a、81~78a以及73~71a等周期,表明该孔SST变化与太阳活动强度是密切相关的。 中晚全新世以来,黑潮流在冲绳海槽逐步加强,到4000aB.P.左右达到最大,然后4000~3000a B.P.期间,黑潮强度明显减弱或者发生东偏,3000aB.P.以后,黑潮强度持续增强,在近1000aB.P.波动较大。 对冲绳海槽地区14个柱状样氧同位素以及P.obliquiloculata丰度进行研究,发现LGM以来,黑潮流可能仍然在冲绳海槽地区活动,并没有移出海槽外,但是由于其强度减弱,其流径发生了很大变化。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

湟水流域位于青海省的东部,约处于北纬35°56′-37°38′,东径100°35′-103°05′。属于青藏高原和黄土高原的过滤地带,海拔1650-4394m,全区面积约16600km^2,属于大陆性气候和高原大陆性气候类型。本区共有野生种子植物83科、400属、1234种。分别占本区所属的青藏高原植物亚区唐古特地区总科数的92.22%、总属数的78.74%、总种数的54.00%。研究表明,湟水流域植物区系特征为:(1)在唐古特地区中种类相对较丰富;(2)温带成分占2.80%,以绝对优势确定了本区系为明显的温带性质(属于以北温带成分,特别是欧亚大陆温、寒地带典型成分为优势的,兼具温性,寒温和高寒类型的温带区系性南,或可称为在温带区第中的过渡区系所具有的“复合型”区系特征);(3)木本类型少,大多数种类为多年生草本植物,缺乏古老和原始类群,一些中国特有种衍生于其广布的亲缘种中,表明本区系具有年轻和衍生的性质;(4)我国西南高山区系和华北区系对该区系具有双重影响;(5)为青藏高原植物亚区唐古特植物地区同华北植物地区相互过渡的代表区系之一;(6)特有属和特有种少。在中国种子植物区系分区中,本区属于青藏高原植物亚区中的唐古特地区。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

湟水地区地处黄土高原和青藏高原过渡带, 界于北纬36°02′~ 37°28′, 东经100°41′~103°04′之间。海拔1650~ 4395m , 总面积为16120 km2。本研究根据卫星遥感影像资料(以TM 为主) , 结合以往野外调查工作, 研究并综合分析了湟水地区的森林、灌丛植被及其主要特征。森林灌丛植被的遥感解译采用综合分析法。研究表明湟水地区森林灌丛植被具有明显的生态地理分布特征, 其分布多集中于黄土低山丘陵与中高山地形结合地带, 即黄土覆盖的边缘交错区域。这一空间分布特征可能与本区的黄土覆盖边缘地区的多样化生态地理特点存在一定的联系。生境的干湿状况直接影响本地区天然林的分布特征、森林灌丛植被覆盖率的高低、森林的类型结构和种类组成, 并成为人工造林效果的重要环境因素。本区森林灌丛植被长期受到人类活动的深刻影响, 具有人类活动的明显痕迹。人类活动的规模范围、作用方式、影响强度等因素成为本区森林灌丛植被及其生境变化与差异的重要原因之一。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

加速度传感器装在机械手手部,各关节的加速度由加速度分解算法得到.然后,提出了一种学习控制法,这种控制法利用加速度误差校正驱动器运动.并提出了一种基于几何级数的极限条件估计学习控制过程收敛条件的理论方法.本文所提出的学习控制理论的有效性通过 PUMA-562 机器人的计算机仿真实验得到了证实.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Basin-scale heterogeneity contains information about the traces of the past sedimentary cycle and tectonic process, and has been a major concern to geophysicists because of its importance in resource exploration and development. In this paper, the sonic data of 30 wells of Sulige field are used to inverse the power-law spectra slope and correlation length which are measures of the heterogeneity of the velocity of the log using fractal and statistic correlation methods. By taking the heterogeneity parameters of different wells interpolated, we get power law spectra slope and correlation length contours reflecting the stratum heterogeneity. Then using correlation and gradient, we inverse the transverse heterogeneity of Sulige field. Reservior-scale heterogeneity influnce the distribution of remaining oil and hydrocarbon accumulation. Using wavelet modulus maximum method to divide the sedimentary cycle using Gr data, therefore we can calculate the heterogeneity parameter in each layer of each log. Then we get the heterogeneity distribution of each layer of Sulige field. Finally, we analyze the relation between the signal sigularity and the strata heterogeneity, and get two different sigularity profiles in different areas.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在岩溶地区大范围内进行土壤侵蚀风险评价需要寻求新的简单有效的方法,建立适合岩溶地区特点的评估模型,才能避免水土流失治理规划的失误。考虑岩溶地区碳酸盐岩成土速率低、存在石漠化等特点,选取土壤允许流失量和退化岩溶生态系统的基岩裸露率,结合年平均降水、坡度、植被指数,在生成各单因素评价图的基础上,在Arcview中完成单因素图的叠加分析,得到贵州省岩溶地区水土流失敏感性综合评价图,并将其划分为不敏感、轻度敏感、中度敏感和强度敏感四级。在此基础上,探讨了贵州省水土流失敏感性的空间分异规律,提出水土流失预防治理的优先区。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

http://www.archive.org/details/samsonoccom00loverich/

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The SafeWeb anonymizing system has been lauded by the press and loved by its users; self-described as "the most widely used online privacy service in the world," it served over 3,000,000 page views per day at its peak. SafeWeb was designed to defeat content blocking by firewalls and to defeat Web server attempts to identify users, all without degrading Web site behavior or requiring users to install specialized software. In this article we describe how these fundamentally incompatible requirements were realized in SafeWeb's architecture, resulting in spectacular failure modes under simple JavaScript attacks. These exploits allow adversaries to turn SafeWeb into a weapon against its users, inflicting more damage on them than would have been possible if they had never relied on SafeWeb technology. By bringing these problems to light, we hope to remind readers of the chasm that continues to separate popular and technical notions of security.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The Java programming language has been widely described as secure by design. Nevertheless, a number of serious security vulnerabilities have been discovered in Java, particularly in the component known as the Bytecode Verifier. This paper describes a method for representing Java security constraints using the Alloy modeling language. It further describes a system for performing a security analysis on any block of Java bytecodes by converting the bytes into relation initializers in Alloy. Any counterexamples found by the Alloy analyzer correspond directly to insecure code. Analysis of a real-world malicious applet is given to demonstrate the efficacy of the approach.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Enterprise Ireland (Project CFTD07325). European Commission (EU Framework 7 project Nanofunction, (Beyond CMOS Nanodevices for Adding Functionalities to CMOS) www.Nanofunction.eu EU ICT Network of Excellence, Grant No.257375)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This study was undertaken to investigate the general biology, including the reproductive cycle and health status, of two clam taxa in Irish waters, with particular reference to the Irish Sea area. Monthly samples of the soft shell clam, Mya arenaria, were collected from Bannow Bay, Co. Wexford, Ireland, for sixteen months, and of the razor clam, Ensis spp. from the Skerries region (Irish Sea) between June 2010 and September 2011. In 2010, M. arenaria in Bannow Bay matured over the summer months, with both sexes either ripe or spawning by August. The gonads of both sexes of E. siliqua developed over autumn and winter 2010, with the first spawning individuals being recorded in January 2011. Two unusually cold winters, followed by a warmer than average spring, appear to have affected M. arenaria and E. siliqua gametogenesis at these sites. It was noted that wet weight of E. siliqua dropped significantly in the summer of both 2010 and 2011, after spawning, which may impact on the economic viability of fishing during this period. Additional samples of M. arenaria were collected at Flaxfort (Ireland), and Ensis spp. at Oxwich (Wales), and the pathology of all clams was examined using both histological and molecular methods. No pathogenic conditions were observed in M. arenaria while Prokaryote inclusions, trematode parasites, Nematopsis spp. and inflammatory pathologies were observed at low incidences in razor clams from Ireland but not from Wales; the first time these conditions have been reported in Ensis spp. in northern European waters. Mya arenaria from sites in Europe and eastern and western North America were investigated for genetic variation using both mitochondrial (cytochrome oxidase I (COI) and 16S ribosomal RNA genes) and nuclear markers (10 microsatellite loci). Both mitochondrial CO1 and all nuclear markers showed reduced levels of variation in certain European samples, with significant differences in haplotype and allelic composition between most samples, particularly those from the two different continents, but with the same common haplotypes or alleles throughout the range. The appearance of certain unique rare haplotypes and microsatellite alleles in the European samples suggest a complicated origin involving North American colonization but also possible southern European Pleistocene refugia. Specimens of Ensis spp. were obtained from five coastal areas around Ireland and Wales and species-specific PCR primers were used to amplify the internal transcribed spacer region 1 (ITS1) and the mitochondrial DNA CO1 gene and all but 15 razor clams were identified as Ensis siliqua. Future investigations should focus on continued monitoring of reproductive biology and pathology of the two clam taxa (in particular, to assess the influence of environmental change), and on genetics of southern European M. arenaria and sequencing the CO1 gene in Ensis individuals to clarify species identity

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Many among the emerging generation of political elites in Africa see the role the European Union (EU) plays in the maintenance of an unprecedented period of peace in Western Europe as an inspirational example of the manner in which the African Union (AU) can contribute to peace and stability in Africa. This doctoral thesis examines security cooperation between the EU and the AU, with a particular focus on the nature and substance of that cooperation. It suggests that despite the establishment of various EU–AU institutions and ties with a role in security policy and cooperation, such security cooperation is limited in substance. This study argues that EU–AU security cooperation is especially constrained by the emergence of alternative partners, most notably China, and by failures of implementation and follow-through. Two case studies, the first dealing with EU–AU cooperation in peacekeeping, and the second addressing the silent water crisis along with the link between water and security, have been analysed in detail to determine the effectiveness and sustainability of the EU–AU partnership. A number of important lessons for regionalism, interregionalism and multilateralism are drawn from the bond between the EU and the AU. This doctoral thesis will prove that, despite an emphasis on the problematic term ‘strategic’ by both EU and AU policymakers, EU–AU cooperation is limited and somewhat lacking in strategic direction. The cooperation between the EU and the AU focuses mainly on EU financial support for AU peacekeeping and specific projects in Africa (e.g. in the water sector), as well as on a limited political dialogue. Nonetheless, the EU–AU link represents the most comprehensive partnership the AU has with any non-African actor. This study will furthermore demonstrate that the United Nations (UN) is an indispensable third-party to their relationship and it is therefore more appropriate to speak of the AU–EU–UN nexus. This doctoral thesis concludes that the AU–EU–UN nexus is an important example of interregionalism in a global context and that such interregionalism is an important emerging part of global governance.