BMP signaling inhibits intestinal stem cell self-renewal through suppression of Wnt-beta-catenin signaling

In humans, mutations in BMPR1A, SMAD4 and PTEN are responsible for juvenile polyposis syndrome, juvenile intestinal polyposis and Cowden disease, respectively. The development of polyposis is a common feature of these diseases, suggesting that there is an association between BMP and PTEN pathways. The mechanistic link between BMP and PTEN pathways and the related etiology of juvenile polyposis is unresolved. Here we show that conditional inactivation of Bmpr1a in mice disturbs homeostasis of intestinal epithelial regeneration with an expansion of the stem and progenitor cell populations, eventually leading to intestinal polyposis resembling human juvenile polyposis syndrome. We show that BMP signaling suppresses Wnt signaling to ensure a balanced control of stem cell self-renewal. Mechanistically, PTEN, through phosphatidylinosital-3 kinase-Akt, mediates the convergence of the BMP and Wnt pathways on control of beta-catenin. Thus, BMP signaling may control the duplication of intestinal stem cells, thereby preventing crypt fission and the subsequent increase in crypt number.     

Mutations in SEC63 cause autosomal dominant polycystic liver disease

Mutations in PRKCSH, encoding the beta-subunit of glucosidase II, an N-linked glycan-processing enzyme in the endoplasmic reticulum (ER), cause autosomal dominant polycystic liver disease. We found that mutations in SEC63, encoding a component of the protein translocation machinery in the ER, also cause this disease. These findings are suggestive of a role for cotranslational protein-processing pathways in maintaining epithelial luminal structure and implicate noncilial ER proteins in human polycystic disease.     

An improved spatially aware routing algorithm for mobile ad hoc network in inter-vehicle communication

A new algorithm called spatially aware routing algorithm with enhanced learning (SAREL) is proposed to guarantee the rationality of route selecting in inter-vehicle communication scenario. Firstly, the traffic model is discussed and set up by using Poisson distribution. Then we analyze the process of traffic evaluation with enhanced learning, and exploit movement estimation to assist state memorization. The improvement of algorithm is provided at last compared with our previous work. Simulation results show that SAREL algorithm could achieve better performance in packet delivery ratio, especially when network connection ratio is average.     

Optimization of short-pulse GPR transmit antenna

By analyzing the current distribution of Bow-Tie amerma used in short-pulse ground penetrating radar, the methods of antenna load and driving are presented in this paper to reduce strength of reflective wave both at antenna end and excitation point. The numerical simulation results show the strength oi reflective wave is smaller than -55dB comparing with the driving wave when the methods are adopted.     

钢铁企业产成品物流控制中转库流向的优化问题

以我国大型钢铁企业上海宝山钢铁集团(公司)为背景,描述了其产成品物流控制中的产成品转库问题,建立了转库流向优化问题的数学规划模型·使用遗传算法,提出一种称为“两段式可重复非负整数编码”的编码策略来获得大规模01规划模型的近优解·计算结果表明,当可用能力足够大并且准发数较少时,结果与SAS/OR的计算结果非常接近·当可用能力不是足够大,并且准发数较多时,计算结果要好于实际调度结果,此时SAS/OR软件在规定的时间内无法算出优化解·     

EL显示器的驱动电路设计

指出了传统EL显示器驱动电路存在的问题,用“平衡驱动”的概念,设计了矩阵式EL显示驱动电路系统。它包括高压驱动电路、逻辑控制电路、波形调制电路、电源电路和接口电路。该电路解决了非平衡驱动方式产生的“潜影”问题。     

大坝背管裂缝宽度计算公式的改进

指出了用现有裂缝理论计算钢衬钢筋混凝土压力管道裂缝宽度的局限性.进一步完善了"外部管壁”的力学模型,并据此导出了精确度更高的半理论半经验公式,该公式考虑了混凝土保护层内外的裂缝宽度差异.最后给出了算例.     

Glycine binding primes NMDA receptor internalization

NMDA (N-methyl-d-aspartate) receptors (NMDARs) are a principal subtype of excitatory ligand-gated ion channel with prominent roles in physiological and disease processes in the central nervous system. Recognition that glycine potentiates NMDAR-mediated currents as well as being a requisite co-agonist of the NMDAR subtype of 'glutamate' receptor profoundly changed our understanding of chemical synaptic communication in the central nervous system. The binding of both glycine and glutamate is necessary to cause opening of the NMDAR conductance pore. Although binding of either agonist alone is insufficient to cause current flow through the channel, we report here that stimulation of the glycine site initiates signalling through the NMDAR complex, priming the receptors for clathrin-dependent endocytosis. Glycine binding alone does not cause the receptor to be endocytosed; this requires both glycine and glutamate site activation of NMDARs. The priming effect of glycine is mimicked by the NMDAR glycine site agonist d-serine, and is blocked by competitive glycine site antagonists. Synaptic as well as extrasynaptic NMDARs are primed for internalization by glycine site stimulation. Our results demonstrate transmembrane signal transduction through activating the glycine site of NMDARs, and elucidate a model for modulating cell-cell communication in the central nervous system.     

蚂蚁觅食模型及其行为

提出一个描述蚂蚁觅食行为的计算机模拟模型,并对此模型展示的倍周期分岔行为进行解释,即由于觅食行为中个体之间信息传递和收到信息之后采取行动需要时间而引起的“信息滞后”,这是一种新观点,可以称为“信息滞后打破均衡”。