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11.
Construction of high resolution images from low resolution sequences having rigid or semi-rigid objects with unified motions is often important in surveillance and other applications. In this paper a novel object-based super resolution reconstruction scheme was proposed, in which a six-parameter affine model-based object tracking and registration method was first used to segment and match objects among a sequence of low resolution frames. The motion model was then further extended to the traditional maximum a posterior (MAP) super resolution algorithm. The proposed object tracking and registration method was evaluated by both simulated and real acquired sequences. The results have demonstrated the high accuracy of the proposed object based method and the enhanced reconstruction performance of the extended approach. 相似文献
12.
Introduction Nucleate boiling has always been an important heat transfer mechanism in many fields, such as energy utilization, manufacturing processes, and chemical processing and nucleate boiling continues to find new applications in many new areas, such… 相似文献
13.
Persistence of soil organic matter as an ecosystem property 总被引:65,自引:0,他引:65
Schmidt MW Torn MS Abiven S Dittmar T Guggenberger G Janssens IA Kleber M Kögel-Knabner I Lehmann J Manning DA Nannipieri P Rasse DP Weiner S Trumbore SE 《Nature》2011,478(7367):49-56
Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily--and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming. 相似文献
14.
Kittler R Putz G Pelletier L Poser I Heninger AK Drechsel D Fischer S Konstantinova I Habermann B Grabner H Yaspo ML Himmelbauer H Korn B Neugebauer K Pisabarro MT Buchholz F 《Nature》2004,432(7020):1036-1040
RNA interference (RNAi) is an evolutionarily conserved defence mechanism whereby genes are specifically silenced through degradation of messenger RNAs; this process is mediated by homologous double-stranded (ds)RNA molecules. In invertebrates, long dsRNAs have been used for genome-wide screens and have provided insights into gene functions. Because long dsRNA triggers a nonspecific interferon response in many vertebrates, short interfering (si)RNA or short hairpin (sh)RNAs must be used for these organisms to ensure specific gene silencing. Here we report the generation of a genome-scale library of endoribonuclease-prepared short interfering (esi)RNAs from a sequence-verified complementary DNA collection representing 15,497 human genes. We used 5,305 esiRNAs from this library to screen for genes required for cell division in HeLa cells. Using a primary high-throughput cell viability screen followed by a secondary high content videomicroscopy assay, we identified 37 genes required for cell division. These include several splicing factors for which knockdown generates mitotic spindle defects. In addition, a putative nuclear-export terminator was found to speed up cell proliferation and mitotic progression after knockdown. Thus, our study uncovers new aspects of cell division and establishes esiRNA as a versatile approach for genomic RNAi screens in mammalian cells. 相似文献
15.
论述了目前的软件开发中存在的两个问题:①现有的高级语言对各种高级计算模型支持的不足;②快速原型开发和高质量产品开发之间的矛盾,针对上问题,设计了一种新的面向对象语言Transframe并研制了它的开发环境MagicFrame.Transframe语言具有的参数化的动态类、名的一般模型、类与函数概念的统一、成员类继承和代理等多种机制为构造各种领域模型提供了有力的支持。基于Transframe的开发环 相似文献
16.
17.
The genome sequence of the rice blast fungus Magnaporthe grisea 总被引:8,自引:0,他引:8
Dean RA Talbot NJ Ebbole DJ Farman ML Mitchell TK Orbach MJ Thon M Kulkarni R Xu JR Pan H Read ND Lee YH Carbone I Brown D Oh YY Donofrio N Jeong JS Soanes DM Djonovic S Kolomiets E Rehmeyer C Li W Harding M Kim S Lebrun MH Bohnert H Coughlan S Butler J Calvo S Ma LJ Nicol R Purcell S Nusbaum C Galagan JE Birren BW 《Nature》2005,434(7036):980-986
Magnaporthe grisea is the most destructive pathogen of rice worldwide and the principal model organism for elucidating the molecular basis of fungal disease of plants. Here, we report the draft sequence of the M. grisea genome. Analysis of the gene set provides an insight into the adaptations required by a fungus to cause disease. The genome encodes a large and diverse set of secreted proteins, including those defined by unusual carbohydrate-binding domains. This fungus also possesses an expanded family of G-protein-coupled receptors, several new virulence-associated genes and large suites of enzymes involved in secondary metabolism. Consistent with a role in fungal pathogenesis, the expression of several of these genes is upregulated during the early stages of infection-related development. The M. grisea genome has been subject to invasion and proliferation of active transposable elements, reflecting the clonal nature of this fungus imposed by widespread rice cultivation. 相似文献
18.
RNAi-mediated gene silencing in non-human primates 总被引:2,自引:0,他引:2
Zimmermann TS Lee AC Akinc A Bramlage B Bumcrot D Fedoruk MN Harborth J Heyes JA Jeffs LB John M Judge AD Lam K McClintock K Nechev LV Palmer LR Racie T Röhl I Seiffert S Shanmugam S Sood V Soutschek J Toudjarska I Wheat AJ Yaworski E Zedalis W Koteliansky V Manoharan M Vornlocher HP MacLachlan I 《Nature》2006,441(7089):111-114
The opportunity to harness the RNA interference (RNAi) pathway to silence disease-causing genes holds great promise for the development of therapeutics directed against targets that are otherwise not addressable with current medicines. Although there are numerous examples of in vivo silencing of target genes after local delivery of small interfering RNAs (siRNAs), there remain only a few reports of RNAi-mediated silencing in response to systemic delivery of siRNA, and there are no reports of systemic efficacy in non-rodent species. Here we show that siRNAs, when delivered systemically in a liposomal formulation, can silence the disease target apolipoprotein B (ApoB) in non-human primates. APOB-specific siRNAs were encapsulated in stable nucleic acid lipid particles (SNALP) and administered by intravenous injection to cynomolgus monkeys at doses of 1 or 2.5 mg kg(-1). A single siRNA injection resulted in dose-dependent silencing of APOB messenger RNA expression in the liver 48 h after administration, with maximal silencing of >90%. This silencing effect occurred as a result of APOB mRNA cleavage at precisely the site predicted for the RNAi mechanism. Significant reductions in ApoB protein, serum cholesterol and low-density lipoprotein levels were observed as early as 24 h after treatment and lasted for 11 days at the highest siRNA dose, thus demonstrating an immediate, potent and lasting biological effect of siRNA treatment. Our findings show clinically relevant RNAi-mediated gene silencing in non-human primates, supporting RNAi therapeutics as a potential new class of drugs. 相似文献
19.
Caloric restriction extends lifespan in numerous species. In the budding yeast Saccharomyces cerevisiae this effect requires Sir2 (ref. 1), a member of the sirtuin family of NAD+-dependent deacetylases. Sirtuin activating compounds (STACs) can promote the survival of human cells and extend the replicative lifespan of yeast. Here we show that resveratrol and other STACs activate sirtuins from Caenorhabditis elegans and Drosophila melanogaster, and extend the lifespan of these animals without reducing fecundity. Lifespan extension is dependent on functional Sir2, and is not observed when nutrients are restricted. Together these data indicate that STACs slow metazoan ageing by mechanisms that may be related to caloric restriction. 相似文献
20.
HIV preferentially infects HIV-specific CD4+ T cells 总被引:34,自引:0,他引:34
Douek DC Brenchley JM Betts MR Ambrozak DR Hill BJ Okamoto Y Casazza JP Kuruppu J Kunstman K Wolinsky S Grossman Z Dybul M Oxenius A Price DA Connors M Koup RA 《Nature》2002,417(6884):95-98
HIV infection is associated with the progressive loss of CD4(+) T cells through their destruction or decreased production. A central, yet unresolved issue of HIV disease is the mechanism for this loss, and in particular whether HIV-specific CD4(+) T cells are preferentially affected. Here we show that HIV-specific memory CD4(+) T cells in infected individuals contain more HIV viral DNA than other memory CD4(+) T cells, at all stages of HIV disease. Additionally, following viral rebound during interruption of antiretroviral therapy, the frequency of HIV viral DNA in the HIV-specific pool of memory CD4(+) T cells increases to a greater extent than in memory CD4(+) T cells of other specificities. These findings show that HIV-specific CD4(+) T cells are preferentially infected by HIV in vivo. This provides a potential mechanism to explain the loss of HIV-specific CD4(+) T-cell responses, and consequently the loss of immunological control of HIV replication. Furthermore, the phenomenon of HIV specifically infecting the very cells that respond to it adds a cautionary note to the practice of structured therapy interruption. 相似文献