Drosophila Piwi functions in Hsp90-mediated suppression of phenotypic variation

Canalization, also known as developmental robustness, describes an organism's ability to produce the same phenotype despite genotypic variations and environmental influences. In Drosophila, Hsp90, the trithorax-group proteins and transposon silencing have been previously implicated in canalization. Despite this, the molecular mechanism underlying canalization remains elusive. Here using a Drosophila eye-outgrowth assay sensitized by the dominant Kr(irregular facets-1)(Kr(If-1)) allele, we show that the Piwi-interacting RNA (piRNA) pathway, but not the short interfering RNA or micro RNA pathway, is involved in canalization. Furthermore, we isolated a protein complex composed of Hsp90, Piwi and Hop, the Hsp70/Hsp90 organizing protein homolog, and we demonstrated the function of this complex in canalization. Our data indicate that Hsp90 and Hop regulate the piRNA pathway through Piwi to mediate canalization. Moreover, they point to epigenetic silencing of the expression of existing genetic variants and the suppression of transposon-induced new genetic variation as two major mechanisms underlying piRNA pathway-mediated canalization.     

超长波天文观测微卫星宽带有源天线设计

月球轨道超长波天文观测微卫星(path finder of discovering the sky at the longest wavelengths,DSL-P)是国际首次开展绕月轨道超长波干涉技术验证实验。DSL-P工作频率1~30 MHz,其关键技术之一为宽带有源天线。介绍了DSL-P宽带有源天线的方案,重点分析其噪声特性,通过仿真和测试获取有源天线的噪声性能,分析宽带有源天线对系统设计指标的满足度。研究表明,用于超长波观测的宽带有源天线并不是传统意义上的被动天线和前置放大器的组合,其主要作用是阻抗匹配,并可兼顾噪声要求。     

The PDZ2 domain of zonula occludens-1 and -2 is a phosphoinositide binding domain

Zonula occludens proteins (ZO) are postsynaptic density protein-95 discs large-zonula occludens (PDZ) domain-containing proteins that play a fundamental role in the assembly of tight junctions and establishment of cell polarity. Here, we show that the second PDZ domain of ZO-1 and ZO-2 binds phosphoinositides (PtdInsP) and we identified critical residues involved in the interaction. Furthermore, peptide and PtdInsP binding of ZO PDZ2 domains are mutually exclusive. Although lipid binding does not seem to be required for plasma membrane localisation of ZO-1, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P ₂) binding to the PDZ2 domain of ZO-2 regulates ZO-2 recruitment to nuclear speckles. Knockdown of ZO-2 expression disrupts speckle morphology, indicating that ZO-2 might play an active role in formation and stabilisation of these subnuclear structures. This study shows for the first time that ZO isoforms bind PtdInsPs and offers an alternative regulatory mechanism for the formation and stabilisation of protein complexes in the nucleus.     

我国高校科研态势与科研体制改革对策

我国高校科研在全国科研体系中占有重要地位,同时在科研评价导向、协作机制、科研经费管理、大学功能与创新文化等方面存在不利于科研质量提升的问题。本文分析提出了为实现高校科技创新而应当采取的科研体制改革对策,主要包括：明晰高校新的功能定位;改进科研评价体系;加强高校内外的资源互补性合作;建立科研项目间接经费补偿机制;培育大学精神与创新文化。     

自动化立体仓库固定货架货位的优化研究

通过对自动化立体仓库总体工作过程和存储模式的分析,提出了一种基于作业时间的固定货架的货位优化设计思想,并应用遗传算法进行了实验验证,证明优化后的货位设计确实提高了仓储作业效率。     

2．4-6．0GHz超宽带低噪声放大器的设计

采用标准0．5μmGaAsPHEMT工艺设计了工作频段在2．4—6GHz可应用于无线局域网（WLAN）和超宽带（UWB）接收机的超宽带低噪声放大器。从宽带电路的选择、高频电路设计的器件选择和电路结构的选择等方面讨论了如何进行超宽带低噪声放大器的设计。结果表明,通过合适的电路结构和器件参数选择,可以采用0．5μmGaAsPHEMT工艺制备满足超宽带系统要求的低噪声放大器。在UWB3．1～5．15GHz低频带内,该LNA增益20．8～21．6dB,噪声系数低于0．9～1．1dB,输入输出驻波比均小于一10dB。在2．4～3GHz频带（涵盖802．11b／g的使用范围）内,该LNA增益20．8～21．5dB,噪声系数低于2dB,输入输出驻波比均小于-10dB。在频带5．2—6GHz,该LNA的噪声系数增大到1．332dB。增益则从21．4dB下降到19．7dB。电路的工作电压为3．3V。     

可调冲压喷管变流量固冲发动机工作特性分析

不可调固冲发动机在飞行中常处于非设计工作点,为改善该类发动机工作性能,目前多采用燃气流量调节的方法。若同时调节冲压喷管,则可大幅改善固冲发动机的适应性。本文基于一维气动理论,建立了可调冲压喷管变流量固冲发动机的数学模型,计算得到了其工作特性。分析表明：与不可调固;中发动机、燃气流量可调固冲发动机相比,可调冲压喷管变流量固冲发动机具有工作域大、阻力低、溢流少、进气道总压损失少以及比冲高等优势。     

地方高师院校生物科学专业师范生创新实验能力的提升

当前在国家大力倡导"大众创业、万众创新"的新形势下,着力构建师范生的创新创业体系,提高创新实验能力,是提升学生科研素养和创新创业能力的必然要求,特别是对于地方本科师范院校而言显得尤为必要.通过分析地方高师院校生物科学专业师范生创新实验现状及原因,提出提升师范生创新实验能力的必要性和提升途径,为培养师范生综合能力,促进毕业生就业和深造提供重要参考.     

A partial robust optimization approach to inventory management for the offline-to-online problem under different selling prices

This study examines an optimal inventory strategy when a retailer markets a product at different selling prices through a dual-channel supply chain, comprising an online channel and an offline channel. Using the operating pattern of the offline-to-online (O2O) business model, we develop a partial robust optimization (PRO) model. Then, we provide a closed-form solution when only the mean and standard deviation of the online channel demand distribution is known and the offline channel demand follows a uniform distribution (partial robust). Specifically, owing to the good structural properties of the solution, we obtain a heuristic ordering formula for the general distribution case (i.e., the offline channel demand follows a general distribution). In addition, a series of numerical experiments prove the rationality of our conjecture. Moreover, after comparing our solution with other possible policies, we conclude that the PRO approach improves the performance of incorporating the internet into an existing supply chain and, thus, is able to adjust the level of conservativeness of the solution. Finally, in a degenerated situation, we compare our PRO approach with a combination of information approach. The results show that the PRO approach has more “robust” performance. As a result, a reasonable trade-off between robustness and performance is achieved.     

囚徒困境中基于非均匀连接的促合作控制设计

本文研究"囚徒困境"中促进合作演化的机制,设计"合作识别"和"背叛识别"两种控制形式,并分析合作在相应控制之下的演化路径问题.在合作识别控制设计中,通过将博弈群体分为合作者子群体和合作者与背叛者共存子群体,形成连接率依赖于个体策略的"非均匀连接",以保护合作的方式抑制背叛,促进合作演化;在背叛识别控制设计中,以惩罚背叛的方式鼓励合作.文章指出,合作识别控制设计能在合作率较低时促进合作,但不能使合作成为演化稳定策略(ESS);背叛识别控制设计能在合作率较高时使合作成为ESS,但是背叛总是该控制下的ESS.结合"合作识别"控制与"背叛识别"控制,本文设计一种切换控制,使得合作是"囚徒困境"博弈的唯一ESS.仿真给出不同要求下的控制律设计,分析不同切换选择对合作演化路径的影响.