排序方式: 共有27条查询结果,搜索用时 15 毫秒
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研究互补问题的新解法,给出了互补问题的一个新的光滑乘子价值函数,分析了乘子价值函数的性质,并构造了相应的算法.选取了新的下降方向和乘子修正方法,使价值函数获得两次下降,从而加快了下降速度.研究结果表明:在函数为一致P的条件下,算法具有全局收敛性、局部超线性收敛性和二次收敛性;对线性互补问题有限步收敛. 相似文献
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Marscher AP Jorstad SG Gómez JL Aller MF Teräsranta H Lister ML Stirling AM 《Nature》2002,417(6889):625-627
Accretion of gas onto black holes is thought to power the relativistic jets of material ejected from active galactic nuclei (AGN) and the 'microquasars' located in our Galaxy. In microquasars, superluminal radio-emitting features appear and propagate along the jet shortly after sudden decreases in the X-ray fluxes. This establishes a direct observational link between the black hole and the jet: the X-ray dip is probably caused by the disappearance of a section of the inner accretion disk as it falls past the event horizon, while the remainder of the disk section is ejected into the jet, creating the appearance of a superluminal bright spot. No such connection has hitherto been established for AGN, because of insufficient multi-frequency data. Here we report the results of three years of monitoring the X-ray and radio emission of the galaxy 3C120. As has been observed for microquasars, we find that dips in the X-ray emission are followed by ejections of bright superluminal knots in the radio jet. The mean time between X-ray dips appears to scale roughly with the mass of the black hole, although there are at present only a few data points. 相似文献
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Dmitry Sidorov Steven J. Taylor Svetlana Sharina Andrey Gontcharov 《Journal of Natural History》2018,52(23-24):1509-1535
Previous phylogenetic analysis based on combined mitochondrial and nuclear gene sequences detected paraphyly of the Typhlogammaridae. To test this hypothesis a portion of large subunit (LSU-rDNA) gene sequences were obtained for typhlogammarid species from Caucasus. The Bayesian approach to LSU-rDNA sequences provided evidence for an independent origin of the Dinaric and Caucasus ‘typhlogammarid’ clades. A new family, Zenkevitchiidae fam. nov., is proposed to reconcile the observed phylogeny with the concept of monophyly. Using light microscopy, two mouthpart morphotypes of the Zenkevitchiidae fam. nov. species with quite different setae are identified. Taking into account these two morphotypes, a new classification is proposed – Adaugammarus revazi comb. nov., and Adaugammarus sandroruffoi comb. nov. Additionally, two new stygobiont zenkevitchiid amphipod species – Adaugammarus kasiani sp. nov. and Kruberia relicta sp. nov. – are described from Krubera Cave in Abkhazia. A distribution map and an identification key for the Zenkevitchiidae fam. nov. species of Transcaucasia are provided.
http://zoobank.org/urn:lsid:zoobank.org:pub:90177B0C-BED0-4601-8CFC-3F774B22065C 相似文献
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Mutant small heat-shock protein 27 causes axonal Charcot-Marie-Tooth disease and distal hereditary motor neuropathy 总被引:25,自引:0,他引:25
Evgrafov OV Mersiyanova I Irobi J Van Den Bosch L Dierick I Leung CL Schagina O Verpoorten N Van Impe K Fedotov V Dadali E Auer-Grumbach M Windpassinger C Wagner K Mitrovic Z Hilton-Jones D Talbot K Martin JJ Vasserman N Tverskaya S Polyakov A Liem RK Gettemans J Robberecht W De Jonghe P Timmerman V 《Nature genetics》2004,36(6):602-606
Charcot-Marie-Tooth disease (CMT) is the most common inherited neuromuscular disease and is characterized by considerable clinical and genetic heterogeneity. We previously reported a Russian family with autosomal dominant axonal CMT and assigned the locus underlying the disease (CMT2F; OMIM 606595) to chromosome 7q11-q21 (ref. 2). Here we report a missense mutation in the gene encoding 27-kDa small heat-shock protein B1 (HSPB1, also called HSP27) that segregates in the family with CMT2F. Screening for mutations in HSPB1 in 301 individuals with CMT and 115 individuals with distal hereditary motor neuropathies (distal HMNs) confirmed the previously observed mutation and identified four additional missense mutations. We observed the additional HSPB1 mutations in four families with distal HMN and in one individual with CMT neuropathy. Four mutations are located in the Hsp20-alpha-crystallin domain, and one mutation is in the C-terminal part of the HSP27 protein. Neuronal cells transfected with mutated HSPB1 were less viable than cells expressing the wild-type protein. Cotransfection of neurofilament light chain (NEFL) and mutant HSPB1 resulted in altered neurofilament assembly in cells devoid of cytoplasmic intermediate filaments. 相似文献
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互补问题的一种新Lagrange乘子法 总被引:1,自引:0,他引:1
利用文献中给出的NCP函数,将互补问题转化为非光滑方程组的求解问题,构造了解该方程组的新的Lagrange乘子法,在函数为一致P函数的条件下,证明了算法的全局收敛性、局部超线性收敛性和二次收敛性,以及对线性互补问题的有限步终止性,数值实验表明,算法是有效的。 相似文献