排序方式: 共有149条查询结果,搜索用时 218 毫秒
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Bart Legein Lieve Temmerman Erik A. L. Biessen Esther Lutgens 《Cellular and molecular life sciences : CMLS》2013,70(20):3847-3869
Cardiovascular disease (CVD) is the leading cause of mortality worldwide, accounting for 16.7 million deaths each year. The underlying cause of the majority of CVD is atherosclerosis. In the past, atherosclerosis was considered to be the result of passive lipid accumulation in the vessel wall. Today’s picture is far more complex. Atherosclerosis is considered a chronic inflammatory disease that results in the formation of plaques in large and mid-sized arteries. Both cells of the innate and the adaptive immune system play a crucial role in its pathogenesis. By transforming immune cells into pro- and anti-inflammatory chemokine- and cytokine-producing units, and by guiding the interactions between the different immune cells, the immune system decisively influences the propensity of a given plaque to rupture and cause clinical symptoms like myocardial infarction and stroke. In this review, we give an overview on the newest insights in the role of different immune cells and subtypes in atherosclerosis. 相似文献
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The superstatistics concept is a useful statistical method to describe inhomogeneous complex systems for which a system parameter βfluctuatesonalargespatio-temporal scale. Inthispaper weanalyze ameasuredtimeseriesofwindspeed fluctuationsandextract the superstatistical distribution function f(β) directly from the data. We construct suitable Langevin and Fokker-Planck models with a position dependent β-field and show that they reduce to standard type of superstatistics in the overdamped limit. 相似文献
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Qvarnstr?m et al. test whether the preference of female collared flycatchers (Ficedula albicollis) for males with large forehead patches could have evolved as a by-product of selection acting on male patch size. They find that the crucial genetic correlation between female choice and male patch size is not significant, and conclude that preference for large patches must have been shaped directly by selection. However, their use of the patch size of a female's social partner as a measure of choice is incomplete, and will result in low estimates of the potential for direct selection to shape female preference. Their study is therefore unable to resolve the question of how female preference for large forehead patches has evolved. 相似文献
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Global efforts to conserve species have been strongly influenced by the heterogeneous distribution of species diversity across the Earth. This is manifest in conservation efforts focused on diversity hotspots. The conservation of genetic diversity within an individual species is an important factor in its survival in the face of environmental changes and disease. Here we show that diversity within species is also distributed unevenly. Using simple genealogical models, we show that genetic distinctiveness has a scale-free power law distribution. This property implies that a disproportionate fraction of the diversity is concentrated in small sub-populations, even when the population is well-mixed. Small groups are of such importance to overall population diversity that even without extrinsic perturbations, there are large fluctuations in diversity owing to extinctions of these small groups. We also show that diversity can be geographically non-uniform--potentially including sharp boundaries between distantly related organisms--without extrinsic causes such as barriers to gene flow or past migration events. We obtained these results by studying the fundamental scaling properties of genealogical trees. Our theoretical results agree with field data from global samples of Pseudomonas bacteria. Contrary to previous studies, our results imply that diversity loss owing to severe extinction events is high, and focusing conservation efforts on highly distinctive groups can save much of the diversity. 相似文献
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Palstra RJ Tolhuis B Splinter E Nijmeijer R Grosveld F de Laat W 《Nature genetics》2003,35(2):190-194
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Fossil evidence for an ancient divergence of lorises and galagos 总被引:3,自引:0,他引:3
Morphological, molecular, and biogeographic data bearing on early primate evolution suggest that the clade containing extant (or 'crown') strepsirrhine primates (lemurs, lorises and galagos) arose in Afro-Arabia during the early Palaeogene, but over a century of palaeontological exploration on that landmass has failed to uncover any conclusive support for that hypothesis. Here we describe the first demonstrable crown strepsirrhines from the Afro-Arabian Palaeogene--a galagid and a possible lorisid from the late middle Eocene of Egypt, the latter of which provides the earliest fossil evidence for the distinctive strepsirrhine toothcomb. These discoveries approximately double the previous temporal range of undoubted lorisiforms and lend the first strong palaeontological support to the hypothesis of an ancient Afro-Arabian origin for crown Strepsirrhini and an Eocene divergence of extant lorisiform families. 相似文献
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芦爱国 《南京邮电大学学报(自然科学版)》1995,(2)
介绍了基于现场可编程门阵列(FPGA)查阅表的逻辑优化准则.基于这一准则,讨论了几种重要的逻辑优化运算,例如抽取、分解、约数检查和简化,以按照目标工艺技术估算电路的价格.基于FPGA,利用我们的方法对查阅表进行逻辑优化,可以得到工艺映射中的良好出发点.以25个基准试验例子为基础,我们的优化电路所需要的构造逻辑方块(CLB)比利用MIS-II的优化电路的情形下少百分之十四,如果两者都利用MIS-pga顺序映射的话.此外,电路的级数也稍有改进. 相似文献
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We develop Hawkes models in which events are triggered through self‐excitation as well as cross‐excitation. We examine whether incorporating cross‐excitation improves the forecasts of extremes in asset returns compared to only self‐excitation. The models are applied to US stocks, bonds and dollar exchange rates. We predict the probability of crashes in the series and the value at risk (VaR) over a period that includes the financial crisis of 2008 using a moving window. A Lagrange multiplier test suggests the presence of cross‐excitation for these series. Out‐of‐sample, we find that the models that include spillover effects forecast crashes and the VaR significantly more accurately than the models without these effects. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献