Selective Smoothed Finite Element Method

The paper examines three selective schemes for the smoothed finite element method (SFEM) which was formulated by incorporating a cell-wise strain smoothing operation into the standard compatible finite element method (FEM). These selective SFEM schemes were formulated based on three selective integration FEM schemes with similar properties found between the number of smoothing cells in the SFEM and the number of Gaussian integration points in the FEM. Both scheme 1 and scheme 2 are free of nearly incompressible locking, but scheme 2 is more general and gives better results than scheme 1. In addition, scheme 2 can be applied to anisotropic and nonlinear situations, while scheme 1 can only be applied to isotropic and linear situations. Scheme 3 is free of shear locking. This scheme can be applied to plate and shell problems. Results of the numerical study show that the selective SFEM schemes give more accurate results than the FEM schemes.     

Climate-driven trends in contemporary ocean productivity

Contributing roughly half of the biosphere's net primary production (NPP), photosynthesis by oceanic phytoplankton is a vital link in the cycling of carbon between living and inorganic stocks. Each day, more than a hundred million tons of carbon in the form of CO2 are fixed into organic material by these ubiquitous, microscopic plants of the upper ocean, and each day a similar amount of organic carbon is transferred into marine ecosystems by sinking and grazing. The distribution of phytoplankton biomass and NPP is defined by the availability of light and nutrients (nitrogen, phosphate, iron). These growth-limiting factors are in turn regulated by physical processes of ocean circulation, mixed-layer dynamics, upwelling, atmospheric dust deposition, and the solar cycle. Satellite measurements of ocean colour provide a means of quantifying ocean productivity on a global scale and linking its variability to environmental factors. Here we describe global ocean NPP changes detected from space over the past decade. The period is dominated by an initial increase in NPP of 1,930 teragrams of carbon a year (Tg C yr(-1)), followed by a prolonged decrease averaging 190 Tg C yr(-1). These trends are driven by changes occurring in the expansive stratified low-latitude oceans and are tightly coupled to coincident climate variability. This link between the physical environment and ocean biology functions through changes in upper-ocean temperature and stratification, which influence the availability of nutrients for phytoplankton growth. The observed reductions in ocean productivity during the recent post-1999 warming period provide insight on how future climate change can alter marine food webs.     

十次幂和问题的解

给出不定方程１０＝ ｙ１０的一组正整数解     

Direct detection of more than 50% of the Duchenne muscular dystrophy mutations by field inversion gels

Duchenne muscular dystrophy (DMD) is an X-linked disorder affecting about 1 in 3,500 males. It is allelic with the milder Becker muscular dystrophy. The biochemical basis for both diseases is unknown and no effective treatment is available. Long-range physical mapping has shown that the DMD gene, localized in Xp21, is extremely large, exceeding 2 million base pairs. Until now, carrier detection and prenatal diagnosis has involved the use of linked restriction fragment length polymorphism markers which detect muscular dystrophy-associated deletions in about 10% of the cases. Field inversion gel electrophoresis (FIGE) allows the detection of structural rearrangements in 21 out of 39 of the DMD patients studied (54%), of which 14 (65%) were not detected by conventional methods. Large deletions seem to make up a much higher fraction of the DMD mutations than so far indicated by other methods. A region prone to deletion was located in the distal half of the gene. FIGE analysis could provide a valuable extension of information for carrier detection and prenatal diagnosis. The technique should be generally applicable to the study of diseases involving structural chromosomal rearrangements.     

基于分级遗传算法的结构损伤识别方法

提出了一种基于遗传算法的利用不完整振动数据识别结构损伤的新方法，该方法首先扩展不完整的振型并利用单元能量熵差比确定结构损伤的大致位置，然后采用二级搜索策略，借助遗传算法确定结构损伤的程度，数值计算结果表明，当可能的损伤区域较大时，本方法较直接搜索策略更能有效地确定结构损伤的程度。     

Sirtuin activators mimic caloric restriction and delay ageing in metazoans

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.     

A general model for ontogenetic growth.

Several equations have been proposed to describe ontogenetic growth trajectories for organisms justified primarily on the goodness of fit rather than on any biological mechanism. Here, we derive a general quantitative model based on fundamental principles for the allocation of metabolic energy between maintenance of existing tissue and the production of new biomass. We thus predict the parameters governing growth curves from basic cellular properties and derive a single parameterless universal curve that describes the growth of many diverse species. The model provides the basis for deriving allometric relationships for growth rates and the timing of life history events.     

沥青混合料水稳定性分析

根据沥青混合料的强度形成原理和破坏机理以及沥青混合料与水相互作用机理，着重从集料性质、沥青性质、混合料类型、集料粒径和面层压实层厚度等方面分析了影响沥青混合料水稳定性的因素，提出了应在集料选择、沥青选择、沥青混合料设计、加热与拌和、碾压工艺、环境等方面采取措施来改善沥青混合料的水稳定性。     

The ELF3 zeitnehmer regulates light signalling to the circadian clock

The circadian system regulates 24-hour biological rhythms and seasonal rhythms, such as flowering. Long-day flowering plants like Arabidopsis thaliana, measure day length with a rhythm that is not reset at lights-off, whereas short-day plants measure night length on the basis of circadian rhythm of light sensitivity that is set from dusk, early flowering 3 (elf3) mutants of Arabidopsis are aphotoperiodic and exhibit light-conditional arrhythmias. Here we show that the elf3-7 mutant retains oscillator function in the light but blunts circadian gating of CAB gene activation, indicating that deregulated phototransduction may mask rhythmicity. Furthermore, elf3 mutations confer the resetting pattern of short-day photoperiodism, indicating that gating of phototransduction may control resetting. Temperature entrainment can bypass the requirement for normal ELF3 function for the oscillator and partially restore rhythmic CAB expression. Therefore, ELF3 specifically affects light input to the oscillator, similar to its function in gating CAB activation, allowing oscillator progression past a light-sensitive phase in the subjective evening. ELF3 provides experimental demonstration of the zeitnehmer ('time-taker') concept.     

Inactivation of the apoptosis effector Apaf-1 in malignant melanoma

Metastatic melanoma is a deadly cancer that fails to respond to conventional chemotherapy and is poorly understood at the molecular level. p53 mutations often occur in aggressive and chemoresistant cancers but are rarely observed in melanoma. Here we show that metastatic melanomas often lose Apaf-1, a cell-death effector that acts with cytochrome c and caspase-9 to mediate p53-dependent apoptosis. Loss of Apaf-1 expression is accompanied by allelic loss in metastatic melanomas, but can be recovered in melanoma cell lines by treatment with the methylation inhibitor 5-aza-2'-deoxycytidine (5aza2dC). Apaf-1-negative melanomas are invariably chemoresistant and are unable to execute a typical apoptotic programme in response to p53 activation. Restoring physiological levels of Apaf-1 through gene transfer or 5aza2dC treatment markedly enhances chemosensitivity and rescues the apoptotic defects associated with Apaf-1 loss. We conclude that Apaf-1 is inactivated in metastatic melanomas, which leads to defects in the execution of apoptotic cell death. Apaf-1 loss may contribute to the low frequency of p53 mutations observed in this highly chemoresistant tumour type.