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排序方式: 共有620条查询结果,搜索用时 15 毫秒
401.
P Dutta G Courties Y Wei F Leuschner R Gorbatov CS Robbins Y Iwamoto B Thompson AL Carlson T Heidt MD Majmudar F Lasitschka M Etzrodt P Waterman MT Waring AT Chicoine AM van der Laan HW Niessen JJ Piek BB Rubin J Butany JR Stone HA Katus SA Murphy DA Morrow MS Sabatine C Vinegoni MA Moskowitz MJ Pittet P Libby CP Lin FK Swirski R Weissleder M Nahrendorf 《Nature》2012,487(7407):325-329
During progression of atherosclerosis, myeloid cells destabilize lipid-rich plaques in the arterial wall and cause their rupture, thus triggering myocardial infarction and stroke. Survivors of acute coronary syndromes have a high risk of recurrent events for unknown reasons. Here we show that the systemic response to ischaemic injury aggravates chronic atherosclerosis. After myocardial infarction or stroke, Apoe-/- mice developed larger atherosclerotic lesions with a more advanced morphology. This disease acceleration persisted over many weeks and was associated with markedly increased monocyte recruitment. Seeking the source of surplus monocytes in plaques, we found that myocardial infarction liberated haematopoietic stem and progenitor cells from bone marrow niches via sympathetic nervous system signalling. The progenitors then seeded the spleen, yielding a sustained boost in monocyte production. These observations provide new mechanistic insight into atherogenesis and provide a novel therapeutic opportunity to mitigate disease progression. 相似文献
402.
MAO Pengli;LIN Yan;LI Lin;ZHANG Baochang 《系统科学与复杂性》2025,(4):1803-1822
Remaining useful life(RUL) is a significant challenge in prognostics and health management. Existing methods suffer from a severe performance drop, as testing data from engine sensors exhibits high nonlinearity and complicated fault modes. In this paper, the authors introduce a reinforcement neural architecture search technique based on upper confidence bound(UCB) to optimize an efficient model. UCB explores the combinatorial parameter space of a multi-head convolutional layers concatenate with recurrent layers to search for a suitable architecture. To address the highly nonlinear dataset in complicated working conditions, rainflow counting algorithm is applied to extract features.Experiments are conducted on C-MAPSS dataset. Compared with state-of-the-art, the proposed approach yields better results in both RMSE and scoring function for all the sub-datasets. In multiple working conditions, the authors achieve lower RMSE with significant superiority. The experimental results confirm that the proposed method is an efficient approach for obtaining highly precise RUL predictions. 相似文献
403.
Large sized power transformers are important parts of the power supply chain. These very critical networks of engineering assets are an essential base of a nation's energy resource infrastructure. This research identifies the key factors influencing transformer normal operating conditions and predicts the asset management lifespan. Engineering asset research has developed few lifespan forecasting methods combining real-time monitoring solutions for transformer maintenance and replacement. Utilizing the rich data source from a remote terminal unit (RTU) system for sensor-data driven analysis, this research develops an innovative real-time lifespan forecasting approach applying logistic regression based on the Weibull distribution. The methodology and the implementation prototype are verified using a data series from 161 kV transformers to evaluate the efficiency and accuracy for energy sector applications. The asset stakeholders and suppliers significantly benefit from the real-time power transformer lifespan evaluation for maintenance and replacement decision support. 相似文献
404.
Ding L Getz G Wheeler DA Mardis ER McLellan MD Cibulskis K Sougnez C Greulich H Muzny DM Morgan MB Fulton L Fulton RS Zhang Q Wendl MC Lawrence MS Larson DE Chen K Dooling DJ Sabo A Hawes AC Shen H Jhangiani SN Lewis LR Hall O Zhu Y Mathew T Ren Y Yao J Scherer SE Clerc K Metcalf GA Ng B Milosavljevic A Gonzalez-Garay ML Osborne JR Meyer R Shi X Tang Y Koboldt DC Lin L Abbott R Miner TL Pohl C Fewell G Haipek C Schmidt H Dunford-Shore BH Kraja A Crosby SD Sawyer CS Vickery T Sander S Robinson J 《Nature》2008,455(7216):1069-1075
Determining the genetic basis of cancer requires comprehensive analyses of large collections of histopathologically well-classified primary tumours. Here we report the results of a collaborative study to discover somatic mutations in 188 human lung adenocarcinomas. DNA sequencing of 623 genes with known or potential relationships to cancer revealed more than 1,000 somatic mutations across the samples. Our analysis identified 26 genes that are mutated at significantly high frequencies and thus are probably involved in carcinogenesis. The frequently mutated genes include tyrosine kinases, among them the EGFR homologue ERBB4; multiple ephrin receptor genes, notably EPHA3; vascular endothelial growth factor receptor KDR; and NTRK genes. These data provide evidence of somatic mutations in primary lung adenocarcinoma for several tumour suppressor genes involved in other cancers--including NF1, APC, RB1 and ATM--and for sequence changes in PTPRD as well as the frequently deleted gene LRP1B. The observed mutational profiles correlate with clinical features, smoking status and DNA repair defects. These results are reinforced by data integration including single nucleotide polymorphism array and gene expression array. Our findings shed further light on several important signalling pathways involved in lung adenocarcinoma, and suggest new molecular targets for treatment. 相似文献
405.
在210K的温度下,5.2μm的量子级联激光器在CW运转下输出光功率高于5mW,利用温差电致冷器件即可达到此温度.将激光器放置于铜块上,在210K时,它的热阻抗约为10K/W.使用实验测量得到的T0=136K,J0=535A/cm2,Vop=8.1V和上述的热阻值,理论上可以达到激光运转的最高温度是212K,与实验结果相一致.通过热学模拟显示,由提高激光器的设计和散热,可使热阻抗降低到8.8K/W,从而使激光器运转温度提高到230K。 相似文献
406.
基于链接分析自动侦测Spam页面,提出了一个分阶段机制。采用决策树和链接分析模型对Wikipedia中的所有节点进行Indegree和Outdegree检测,从而产生出一个候选列表,并引入一个启发算法来降低第一类型的错误。设计一个分类器用于分类候选列表,采用TrustRank和SpamRank算法分别从信任种子集和Spam种子集中推算系统页面各自可信概率和Spam概率,从而减少第二类型的错误。然后将产生的候选集合推送至页面编辑,根据编辑判断的结果反馈训练模型,调整权重。结果表明,分阶段侦测模型可自动地侦测Spam页面,其查准率和查全率分别达到78.3%和94%。 相似文献
407.
Lin Sheng Hsien 《华南师范大学学报(自然科学版)》2014,(6):134
Recently sum-frequency has become a very powerful experimental technique in studying structures and dynamic of molecules on surface or molecules between surfaces.In this talk after brief discussion of the derivation of SFG,various possible types of vibrational and electronic SFG’s will be discussed including the derivations of their quantum mechanical expressions based on the Born-Op- 相似文献
408.
Emison ES McCallion AS Kashuk CS Bush RT Grice E Lin S Portnoy ME Cutler DJ Green ED Chakravarti A 《Nature》2005,434(7035):857-863
The identification of common variants that contribute to the genesis of human inherited disorders remains a significant challenge. Hirschsprung disease (HSCR) is a multifactorial, non-mendelian disorder in which rare high-penetrance coding sequence mutations in the receptor tyrosine kinase RET contribute to risk in combination with mutations at other genes. We have used family-based association studies to identify a disease interval, and integrated this with comparative and functional genomic analysis to prioritize conserved and functional elements within which mutations can be sought. We now show that a common non-coding RET variant within a conserved enhancer-like sequence in intron 1 is significantly associated with HSCR susceptibility and makes a 20-fold greater contribution to risk than rare alleles do. This mutation reduces in vitro enhancer activity markedly, has low penetrance, has different genetic effects in males and females, and explains several features of the complex inheritance pattern of HSCR. Thus, common low-penetrance variants, identified by association studies, can underlie both common and rare diseases. 相似文献
409.
Katz HE Lovinger AJ Johnson J Kloc C Siegrist T Li W Lin YY Dodabalapur A 《Nature》2000,404(6777):478-481
Electronic devices based on organic semiconductors offer an attractive alternative to conventional inorganic devices due to potentially lower costs, simpler packaging and compatibility with flexible substrates. As is the case for silicon-based microelectronics, the use of complementary logic elements-requiring n- and p-type semiconductors whose majority charge carriers are electrons and holes, respectively-is expected to be crucial to achieving low-power, high-speed performance. Similarly, the electron-segregating domains of photovoltaic assemblies require both n- and p-type semiconductors. Stable organic p-type semiconductors are known, but practically useful n-type semiconductor materials have proved difficult to develop, reflecting the unfavourable electrochemical properties of known, electron-demanding polymers. Although high electron mobilities have been obtained for organic materials, these values are usually obtained for single crystals at low temperatures, whereas practically useful field-effect transistors (FETs) will have to be made of polycrystalline films that remain functional at room temperature. A few organic n-type semiconductors that can be used in FETs are known, but these suffer from low electron mobility, poor stability in air and/or demanding processing conditions. Here we report a crystallographically engineered naphthalenetetracarboxylic diimide derivative that allows us to fabricate solution-cast n-channel FETs with promising performance at ambient conditions. By integrating our n-channel FETs with solution-deposited p-channel FETs, we are able to produce a complementary inverter circuit whose active layers are deposited entirely from the liquid phase. We expect that other complementary circuit designs can be realized by this approach as well. 相似文献
410.
In this paper, the authors explore the potential of several popular equalization techniques while overcoming their disadvantages. First, extensive literature survey on equalization is conducted. The focus is on popular linear equalization algorithms such as the conventional least-meansquare (LMS) algorithm, the recursive least-squares ( RLS ) algorithm, the filtered-X LMS algorithm and their development. To overcome the slow convergence problem while keeping the simplicity of the LMS based algorithms, an H2 optimal initialization is proposed. 相似文献