Stereoselective Total Synthesis of Mycalamides

Mycalamides A （1a） and B （1b） are potent antiviral compounds from a New Zealand sponge of the genus Mycale. Apart from their antitumor property, mycalamide A （1a） exhibits immunosuppressive action by blocking T-cell activation in mice and is significantly more potent than FK-506 and cyclosporine A. Because of their intriguing biological activity, unique structures and scarce supply of these natural products, mycalamides A （1a） and B （1b） have attracted considerable attention as target molecules for total synthesis, and total, formal, or partial syntheses of this family of compounds have been reported.     

Hans Reichenbach's and C.I. Lewis's Kantian philosophies of science

Recent work in the history of philosophy of science details the Kantianism of philosophers often thought opposed to one another, e.g., Hans Reichenbach, C.I. Lewis, Rudolf Carnap, and Thomas Kuhn. Historians of philosophy of science in the last two decades have been particularly interested in the Kantianism of Reichenbach, Carnap, and Kuhn, and more recently, of Lewis. While recent historical work focuses on recovering the threatened-to-be-forgotten Kantian themes of early twentieth-century philosophy of science, we should not elide the differences between the Kantian strands running throughout this work. In this paper, I disentangle a few of these strands in the work of Reichenbach and Lewis focusing especially on their theories of relativized, constitutive a priori principles in empirical knowledge. In particular, I highlight three related differences between Reichenbach and Lewis concerning their motivations in analyzing scientific knowledge and scientific practice, their differing conceptions of constitutivity, and their relativization of constitutive a priori principles. In light of these differences, I argue Lewis's Kantianism is more similar to Kuhn's Kantianism than Reichenbach's, and so might be of more contemporary relevance to social and practice-based approaches to the philosophy of science.     

Urban structure and the risk of influenza A （H1N1） outbreaks in municipal districts

Changsha was one of the most affected areas during the 2009 A （H 1N 1） influenza pandemic in China. Here, we analyze the spatial-temporal dynamics of the 2009 pan- demic across Changsha municipal districts, evaluate the relationship between case incidence and the local urban spatial structure and predict high-risk areas of influenza A （H1NI）. We obtained epidemiological data on all cases of influenza A （H1NI） reported across municipal districts in Changsha dur- ing period May 2009-December 2010 and data on population density and basic geographic characteristics for 239 primary schools, 97 middle schools, 347 universities, 96 mails and markets, 674 business districts and 121 hospitals. Spatial- temporal K functions, proximity models and logistic regres- sion were used to analyze the spatial distribution pattern of influenza A （H1N1） incidence and the association between influenza A （HINI） cases and spatial risk factors and predict the infection risks. We found that the 2009 influenza A （H 1N 1 ） was driven by a transmission wave from the center of the study area to surrounding areas and reported cases increased significantly after September 2009. We also found that the distribution of influenza A （H 1N1） cases was associ- ated with population density and the presence of nearest public places, especially universities （OR = 10.166）. The final pre- dictive risk map based on the multivariate logistic analysis showed high-risk areas concentrated in the center areas of the study area associated with high population density. Our find- ings support the identification of spatial risk factors and high- risk areas to guide the prioritization of preventive and miti- gation efforts against future influenza pandemics.     

基于群落分布的美国较大港口吞吐能力

为了对美国主要港口的基础条件和吞吐能力有较全面的认识，以美国相关部门的文献数据为基础，运用统计分组法和指标分析法，以群落为对象，对美国较大港口的地理分布、水深条件、桥梁净空和主要货物吞吐量指标进行汇总与分析，发现每个港口群落的地理条件特点虽有不同，但桥梁、航道水深等人工设施均可给予海运尽可能多的便利.通过港口群落之间的指标比较可知，每个港口群落的吞吐能力表现出不同特点，造就了各自在美国经济生活中的不同地位.     

论布依族古歌《罕温与索温》中的鱼龙图腾意象与太阳意象

布依族古歌《罕温与索温》属于布依族宗教经典文本＂摩经＂之《殡亡经》中的一部分,由兄弟夺权和射日洪水两部分故事组成。古歌中出现鱼、龙和太阳等众多文化意象,体现了布依族远古社会这些文化意象的起源与发展以及阶级社会建立后宗法制度的变迁。     

a尺度紧支撑双向正交多小波的构造

自从Geronimo，Hardin和Massopust使用分形插值函数构造出GHM多小波以来，对多小波的研究已引起了很多的关注。出于多通道滤波理论的需要及欲得到比2尺度小波更具灵活性的小波fl尺度多小波理论被引入。2012年，S00n－Ge-ol Kwon在SCI杂志《Applied Mathematicsand Computation》对双向多小波理论做了探讨。但是，双向多小波理论还远未发展成熟，有许多重要论题还有待探讨。文章给出了一类a尺度紧支撑双向正交多小波的构造算法，最后给出双向多小波的构造算例。     

城市污水生化处理系统中总氮去除的影响因素分析

总氮是城市污水处理的一项重要常规指标,在我国现有的城市污水处理工艺中,生化系统中影响脱氮效率的因素主要包括缺氧池容积负荷、混合液回流比、污泥龄和水温等。本研究通过中试试验发现,当缺氧池HRT大于3 hr(对应容积负荷0.24 kg TN·m-3·d-1)、混合液回流比大于150%、污泥龄不小于10d、水温高于20℃时,A2/O可以将平均值为30 mg/L的TN去除到10 mg/L以下,去除率接近70%,稳定达到一级A标准。     

非运输型A2级通用机场布局规划方法

为使通用机场的布局规划与中国通用机场的快速发展保持一致的步伐,根据中国通用机场的类型等级主要提出了A2级通用机场的布局规划方法,分析了A2级通用机场的功能需求与定位,引入了关于A2级通用机场的社会公共服务属性与经济属性,对其进行了详细的分析,并以事故发生风险水平、人口密度和经济规模来表征两大属性,并对其进行加权处理,结合P-中值选址数学模型,对A2级通用机场的救援范围进行建模分析,分析了其预选址个数与加权距离之间的关系,并通过实例验证了该模型和算法的合理性,使A2级通用机场的布局规划更具有可靠性与实际意义。     

关于A/D转换器量化误差与“量化相对误差”的讨论

A/D转换器在转换模拟信号为数字信号时 ,量化误差对大小模拟信号影响不同 ,对小信号转换精度造成的误差较大。为提高小信号的转换精度 ,本文提出量化相对误差问题 ,并给出一种误差平衡法 ,使A/D转换器转换小信号误差较大的问题得以改善。