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排序方式: 共有353条查询结果,搜索用时 15 毫秒
91.
曹元大 《北京理工大学学报》2002,22(4):489-492
设计基于内容的视频编码系统.通过对视频数据的结构和特点的分析,着重描述视频编码系统4个重要组成子模块:场景分析、形状编码、运动编码以及纹理编码子模块的实现,描述本系统中重要对象的数据结构.深入介绍系统中各模块使用的一些新方法:多帧多特征自动提取运动图像的方法,图像填充技术,离散小波变换的方法.设计并实现了功能较为齐全的基于内容的视频编码系统. 相似文献
92.
从多年来的盲人教学实践中总结了盲人在学习钢琴过程中的规律与经验,那就是帮助学生从心理上克服残障,充分发挥盲人听觉、触觉、记忆和想象能力强的优势,使钢琴教学在盲人的群体里得到健康的发展。 相似文献
93.
Modeling European industrial production with multivariate singular spectrum analysis: A cross‐industry analysis 下载免费PDF全文
In this paper, an optimized multivariate singular spectrum analysis (MSSA) approach is proposed to find leading indicators of cross‐industry relations between 24 monthly, seasonally unadjusted industrial production (IP) series for German, French, and UK economies. Both recurrent and vector forecasting algorithms of horizontal MSSA (HMSSA) are considered. The results from the proposed multivariate approach are compared with those obtained via the optimized univariate singular spectrum analysis (SSA) forecasting algorithm to determine the statistical significance of each outcome. The data are rigorously tested for normality, seasonal unit root hypothesis, and structural breaks. The results are presented such that users can not only identify the most appropriate model based on the aim of the analysis, but also easily identify the leading indicators for each IP variable in each country. Our findings show that, for all three countries, forecasts from the proposed MSSA algorithm outperform the optimized SSA algorithm in over 70% of cases. Accordingly, this new approach succeeds in identifying leading indicators and is a viable option for selecting the SSA choices L and r, which minimizes a loss function. 相似文献
94.
Paulo Mateus Martins-Sobrinho Winny Gomes de Oliveira Silva Elizandra Gomes dos Santos Geraldo Jorge Barbosa de Moura Jaqueline Bianque de Oliveira 《Journal of Natural History》2017,51(27-28):1639-1648
Despite the fact that Brazil is the most-studied country regarding helminths of amphibians, only around 8% of Brazilian anurans have had at least one study made of their helminth fauna. Therefore, the aim of this study was to describe the helminth community of nine species of Atlantic Rainforest anurans of two different families, eight of them with no previous study, and six of which are endemic to Brazil. The analysed hosts for their parasites were: Dendropsophus minutus (n = 48), Scinax auratus (n = 36), D. branneri (n = 33), D. elegans (n = 26), Hypsiboas albomarginatus (n = 22), Pithecopus nordestinus (n = 19), D. decipiens (n = 12), D. haddadi (n = 11) and S. x-signatus (n = 11). A total of 781 helminths were collected from 106 (48.6%) of 218 analysed hosts, 656 Centrorhyncus sp. cystacanths and 125 nematodes: 76 adults (25 Cosmocerca sp.; three Cosmocerceidae gen. sp.; 20 Cosmocerca parva, 20 Cosmocercella phyllomedusae, five Aplectana sp., two Oswaldocruzia sp. and one Rhabdias sp.), 43 encysted larvae (nine Porrocaecum sp. and 34 Brevimulticaecum sp.) and six Physaloptera sp. larvae. Anurans may display many roles within the helminth life cycles, as they act as both predator and prey to a wide variety of animals. Consequently, we have found helminths that use anurans as definitive, intermediate and paratenic hosts. Opposing other surveys in which nematodes are the most prevalent and abundant parasites, acanthocephalans were the most prevalent taxa. These findings highlight the lack of knowledge regarding the helminth fauna of anurans and reveal many gaps with respect to their infection patterns in amphibians. 相似文献
95.
Mutations in the gene encoding the 3'-5' DNA exonuclease TREX1 are associated with systemic lupus erythematosus 总被引:1,自引:0,他引:1
Lee-Kirsch MA Gong M Chowdhury D Senenko L Engel K Lee YA de Silva U Bailey SL Witte T Vyse TJ Kere J Pfeiffer C Harvey S Wong A Koskenmies S Hummel O Rohde K Schmidt RE Dominiczak AF Gahr M Hollis T Perrino FW Lieberman J Hübner N 《Nature genetics》2007,39(9):1065-1067
TREX1 acts in concert with the SET complex in granzyme A-mediated apoptosis, and mutations in TREX1 cause Aicardi-Goutières syndrome and familial chilblain lupus. Here, we report monoallelic frameshift or missense mutations and one 3' UTR variant of TREX1 present in 9/417 individuals with systemic lupus erythematosus but absent in 1,712 controls (P = 4.1 x 10(-7)). We demonstrate that two mutant TREX1 alleles alter subcellular targeting. Our findings implicate TREX1 in the pathogenesis of SLE. 相似文献
96.
The spin torque effect that occurs in nanometre-scale magnetic multilayer devices can be used to generate steady-state microwave signals in response to a d.c. electrical current. This establishes a new functionality for magneto-electronic structures that are more commonly used as magnetic field sensors and magnetic memory elements. The microwave power emitted from a single spin torque nano-oscillator (STNO) is at present typically less than 1 nW. To achieve a more useful power level (on the order of microwatts), a device could consist of an array of phase coherent STNOs, in a manner analogous to arrays of Josephson junctions and larger semiconductor oscillators. Here we show that two STNOs in close proximity mutually phase-lock-that is, they synchronize, which is a general tendency of interacting nonlinear oscillator systems. The phase-locked state is distinct, characterized by a sudden narrowing of signal linewidth and an increase in power due to the coherence of the individual oscillators. Arrays of phase-locked STNOs could be used as nanometre-scale reference oscillators. Furthermore, phase control of array elements (phased array) could lead to nanometre-scale directional transmitters and receivers for wireless communications. 相似文献
97.
98.
Second-generation shRNA libraries covering the mouse and human genomes 总被引:23,自引:0,他引:23
99.
Cruz FW Burns SJ Karmann I Sharp WD Vuille M Cardoso AO Ferrari JA Dias PL Viana O 《Nature》2005,434(7029):63-66
During the last glacial period, large millennial-scale temperature oscillations--the 'Dansgaard/Oeschger' cycles--were the primary climate signal in Northern Hemisphere climate archives from the high latitudes to the tropics. But whether the influence of these abrupt climate changes extended to the tropical and subtropical Southern Hemisphere, where changes in insolation are thought to be the main direct forcing of climate, has remained unclear. Here we present a high-resolution oxygen isotope record of a U/Th-dated stalagmite from subtropical southern Brazil, covering the past 116,200 years. The oxygen isotope signature varies with shifts in the source region and amount of rainfall in the area, and hence records changes in atmospheric circulation and convective intensity over South America. We find that these variations in rainfall source and amount are primarily driven by summer solar radiation, which is controlled by the Earth's precessional cycle. The Dansgaard/Oeschger cycles can be detected in our record and therefore we confirm that they also affect the tropical hydrological cycle, but that in southern subtropical Brazil, millennial-scale climate changes are not as dominant as they are in the Northern Hemisphere. 相似文献
100.