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181.
The Mediterranean Sea is known as a biodiversity hot spot, with 16,848 species reported. Biodiversity is higher in coastal areas and decreases with depth. However, knowledge about the southwestern sector remains scarce. For the last three decades, sampling of soft-bottom communities along the 1180 km of the shallow Algerian coast (0–136 m) has recorded 1642 macrobenthic species. There is a decreasing west–east species-richness gradient, especially for the total species richness and the amphipods. In addition, quantitative sampling in Bou Ismail Bay in summer 1988 (98 sampling sites for a total of 841 species) shows that diversity indices (i.e. species richness, >100 species for 0.2 m?2; Shannon diversity, >6.0; and ES50, >34) are among the highest for similar sand and muddy-fine sand communities in the Mediterranean Sea and the northeastern Atlantic Ocean. Bou Ismail Bay appears to have the highest species richness among Algerian bays, probably because of its variety of benthic habitats and the absence of significant pollution in this area. Monitoring must be undertaken to survey this high biodiversity, and a national strategy should be proposed to preserve high diversity zones. 相似文献
182.
分支方法与广义CH方程的显式周期波解 总被引:1,自引:0,他引:1
刘正荣 《华南理工大学学报(自然科学版)》2007,35(10):227-232
用动力系统分支方法和数值模拟的方法去寻找广义CH方程的显式周期波解,首先建立与非线性偏微分方程对应的平面系统,其次绘制出该系统的的分支相图并做计算机数值模拟,确定分支相图中与显式周期波解有关的特殊轨道,最后通过这种特殊轨道及椭圆函数、椭圆积分来获得显式周期波解. 相似文献
183.
Systemic Practice and Action Research - Action research studies in education often address learners’ needs and empower practitioners to effectively change instructional practices and school... 相似文献
184.
New evidence on the robust identification of news shocks: Role of revisions in utilization‐adjusted TFP series and term structure data 下载免费PDF全文
Data revisions and selections of appropriate forwarding‐looking variables have a major impact on true identification of news shocks and quality of research findings derived from structural vector autoregression (SVAR) estimation. This paper revisits news shocks to identify the role of different vintages of total factor productivity (TFP) series and term structure of interest rates as major prognosticators of future economic growth. There is a growing strand of literature regarding the use of utilization‐adjusted TFP series, provided by Fernald (Federal Reserve Bank of San Francisco, Working Paper Series, 2014) for identification of news shocks. We reestimate Barsky and Sims' (Journal of Monetary Economics, 2011, 58, 273–289) empirical analysis by employing 2007 and 2015 vintages of TFP data. We find substantial quantitative as well as qualitative differences among impulse response functions when using 2007 and 2015 vintages of TFP data. Output and hours initially decline, followed by quick reversal of both variables. In sharp contrast to results achieved by the 2007 vintage of TFP data, results achieved by the 2015 vintage of TFP data depict that output and hours will increase in response to positive TFP shock. By including term structure data in our VAR specification, total surprise technology shock and news shock account for 97% and 92% of the forecast error variance in total TFP and total output respectively. We find that revisions in TFP series over time ultimately impact the conclusion regarding news shocks on business cycles. Our results support the notion that term structure data help in better identification of news shock as compared to other forward‐looking variables. 相似文献
185.
186.
Pearson RA Barber AC Rizzi M Hippert C Xue T West EL Duran Y Smith AJ Chuang JZ Azam SA Luhmann UF Benucci A Sung CH Bainbridge JW Carandini M Yau KW Sowden JC Ali RR 《Nature》2012,485(7396):99-103
Cell transplantation is a potential strategy for treating blindness caused by the loss of photoreceptors. Although transplanted rod-precursor cells are able to migrate into the adult retina and differentiate to acquire the specialized morphological features of mature photoreceptor cells, the fundamental question remains whether transplantation of photoreceptor cells can actually improve vision. Here we provide evidence of functional rod-mediated vision after photoreceptor transplantation in adult Gnat1?/? mice, which lack rod function and are a model of congenital stationary night blindness. We show that transplanted rod precursors form classic triad synaptic connections with second-order bipolar and horizontal cells in the recipient retina. The newly integrated photoreceptor cells are light-responsive with dim-flash kinetics similar to adult wild-type photoreceptors. By using intrinsic imaging under scotopic conditions we demonstrate that visual signals generated by transplanted rods are projected to higher visual areas, including V1. Moreover, these cells are capable of driving optokinetic head tracking and visually guided behaviour in the Gnat1?/? mouse under scotopic conditions. Together, these results demonstrate the feasibility of photoreceptor transplantation as a therapeutic strategy for restoring vision after retinal degeneration. 相似文献
187.
Klaus Regenauer-Lieb Andrew Bunger Hui Tong Chua Arcady Dyskin Florian Fusseis Oliver Gaede Rob Jeffrey Ali Karrech Thomas Kohl Jie Liu Vladimir Lyakhovsky Elena Pasternak Robert Podgorney Thomas Poulet Sheik Rahman Christoph Schrank Mike Trefry Manolis Veveakis Bisheng Wu David A. Yuen Florian Wellmann Xi Zhang 《地球科学学刊》2015,(1)
Deep geothermal from the hot crystalline basement has remained an unsolved frontier for the geothermal industry for the past 30 years. This poses the challenge for developing a new un-conventional geom... 相似文献
188.
Platoon formation of highway vehicles is a critical foundation for autonomous or semiautonomous vehicle control for enhanced safety,improved highway utility,increased fuel economy,and reduced emission toward intelligent transportation systems.Platoon control encounters great challenges from vehicle control,communications,team coordination,and uncertainties.This paper introduces a new method for coordinated control of platoons by using integrated network consensus decisions and vehicle control.To achieve suitable coordination of the team vehicles based on terrain and environmental conditions,the emerging technology of network consensus control is modified to a weighted and constrained consensus-seeking framework.Algorithms are introduced and their convergence properties are established.The methodology employs neighborhood information through on-board sensors and V2 V or V2 I communications,but achieves global coordination of the entire platoon.The ability of the methods in terms of robustness,disturbance rejection,noise attenuation,and cyber-physical interaction is analyzed and demonstrated with simulated case studies. 相似文献
189.
用GC/MS/DS的方法对三七的混合脂肪酸甲酯进行分析,共分离鉴定出了7种三七脂肪酸,其中主要成分为8,11-十八碳二烯酸,9,10-二羟基十八烷酸和2-己基癸酸。 相似文献
190.
研究了任意半环上正则元的广义逆的存在性.给出了任意半环上正则元的{1,2}-逆存在的一些充分条件,同时给出了{1,2}-逆存在时的表达式.作为{1,2}-逆的特殊情形,刻画了任意半环上正则元的Moore-Penrose逆和群逆的存在性. 相似文献