Allee effects and pulsed invasion by the gypsy moth

Biological invasions pose considerable threats to the world's ecosystems and cause substantial economic losses. A prime example is the invasion of the gypsy moth in the United States, for which more than $194 million was spent on management and monitoring between 1985 and 2004 alone. The spread of the gypsy moth across eastern North America is, perhaps, the most thoroughly studied biological invasion in the world, providing a unique opportunity to explore spatiotemporal variability in rates of spread. Here we describe evidence for periodic pulsed invasions, defined as regularly punctuated range expansions interspersed among periods of range stasis. We use a theoretical model with parameter values estimated from long-term monitoring data to show how an interaction between strong Allee effects (negative population growth at low densities) and stratified diffusion (most individuals disperse locally, but a few seed new colonies by long-range movement) can explain the invasion pulses. Our results indicate that suppressing population peaks along range borders might greatly slow invasion.     

高功率半导体激光器标准列阵单元及散热器的设计与制作

对高功率半导体激光器的标准列阵单元及散热器进行了设计和制作．采用该标准列阵单元及散热器对不同占空比的二维半导体激光器列阵的测试表明，中间通过插入不同厚度的无氧铜散热片，可有效地把不同负载的热量散发出去，保证器件有效工作，增加可靠性．并且可以通过简单地改变标准单元之间的散热片的厚度，从而改变激光器列阵的散热能力，控制不同的占空比因子。     

垃圾填埋场竖井抽气条件下的填埋气压力分布

对垃圾填埋气污染控制与回收利用系统的规划设计，目前实际工程中通常采用现场抽气试验的方法确定相关技术对数。文章通过分析填埋气在垃圾体中迁移运动的特点，建立了在抽气条件下填埋气体的迁移运动模型，该模型综合反映了垃圾体内填埋气产生量、抽气量、培训班圾体气体渗透系数、抽气井埋深、覆盖层厚度及特性对抽气效果的影响。利用该模型，可计算抽气时垃圾体填埋气的压力分析，并可分析计算不同条件下抽气井影响半径、抽气井埋深等重要工程参数，可为填埋气污染控制与回收利用工程实践提供理论基础与技术依据。     

Linear ubiquitination prevents inflammation and regulates immune signalling

Members of the tumour necrosis factor (TNF) receptor superfamily have important functions in immunity and inflammation. Recently linear ubiquitin chains assembled by a complex containing HOIL-1 and HOIP (also known as RBCK1 and RNF31, respectively) were implicated in TNF signalling, yet their relevance in vivo remained uncertain. Here we identify SHARPIN as a third component of the linear ubiquitin chain assembly complex, recruited to the CD40 and TNF receptor signalling complexes together with its other constituents, HOIL-1 and HOIP. Mass spectrometry of TNF signalling complexes revealed RIP1 (also known as RIPK1) and NEMO (also known as IKKγ or IKBKG) to be linearly ubiquitinated. Mutation of the Sharpin gene (Sharpin(cpdm/cpdm)) causes chronic proliferative dermatitis (cpdm) characterized by inflammatory skin lesions and defective lymphoid organogenesis. Gene induction by TNF, CD40 ligand and interleukin-1β was attenuated in cpdm-derived cells which were rendered sensitive to TNF-induced death. Importantly, Tnf gene deficiency prevented skin lesions in cpdm mice. We conclude that by enabling linear ubiquitination in the TNF receptor signalling complex, SHARPIN interferes with TNF-induced cell death and, thereby, prevents inflammation. Our results provide evidence for the relevance of linear ubiquitination in vivo in preventing inflammation and regulating immune signalling.