Theoretical consideration of effect of fishing mortality on growth and reproduction of fish populations

Summary An increase in fish mortality due to fishing can theoretically change the growth and reproduction of fish populations from the viewpoint of adaptation. We address the issue of how an iteroparous fish should convert surplus energy into somatic growth and reproduction at each age under given conditions of mortality. A model of life history, which maximizes the net reproductive rate using the discrete maximum principle, is improved employing a new relationship between body weight and surplus energy which we have recently proposed. The model is applied to the North Sea plaicePleuronectes platessa, for which it has been reported that the average length of young fish had increased whereas that of old ones had decreased for some decades. Although the model cannot directly explain the former phenomenon, the two phenomena can be interpreted as a change in the optimal life history due mainly to an increase in mortality.     

Sampling Strategies for Toxic Air Contaminants

Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants.     

武汉大学女性教职工婚姻生活调查分析

从武汉大学女教职工关于婚姻生活的满意度、夫妻关系、家庭地位以及家务劳动等方面可以窥见到目前我国高校女教职工婚姻生活质量。     

独立董事“独立性”探讨

独立董事制度的引进,原本是寄期望于此新体制能够完善我国上市公司的公司治理结构。但由于种种原因,这项新制度并没有起到预期的效果,独立董事的"独立性"作用没有得到应有的发挥。我国的独立董事制度建设应具有权威性,赋予给独立董事的权利与其承担的义务应相当。独立董事职责重大,在实践中如何保证他们职责的有效行使是我们应重点考虑的问题,也是独立董事制度能否真正有效的关键。     

假日游览文化与高校图书馆的对外开放

随着假日游览文化的蓬勃发展,假日期间校外人员观摩和利用高校图书馆的要求日益增强,迫使高校图书馆的工作面临着巨大的挑战。然而,只要应对得当,高校图书馆可以也应该发挥自身的独特优势,开拓新的服务领域,在假日期间恰当、有序、合理、适时地向社会开放,则不但能在贯彻"科教兴国"的方针过程中发挥出更大的作用,而且必将为高校图书馆自身的发展提供崭新的机遇。     

湖南绅士与晚清政治变迁

湖南绅士是中国近代史上极具典型意义的特殊社会群体,其崛起特殊,构成复杂,分化缓慢,涉足范围广阔,社会影响深远.这个社会群体不仅直接影响着近代湖南的政局和乡土社会的变迁,而且不断地瓦解着晚清的国家政权,影响着清政府各种制度的变革.     

项目管理:基于生命周期和基于职能活动的管理

对应着项目的"一次性"和"多项活动复合性"的本质特征,项目管理有两种基本模式,即基于生命周期的项目管理和基于职能活动的项目管理,二者的内容体系不同,各有优劣,模式的选用要综合考虑项目的具体性质和企业的发展现状.     

从诗歌创作中看埃米莉·迪金森的智慧人生

沿着埃米莉·迪全森极具个人色彩的人生经历，简要分析了她三首短小却意义深远的诗歌。指出长年沉浸在孤独、沉思中的诗人，所写诗句不仅清新、优美，那些有血、有肉、有灵的篇章更凝结着诗人的心血，也折射出她一生的智慧和情感。诗人坚持用自己的艺术形式和审美标准创作的诗歌必将会深深影响和启迪着读者的心智．     

宗族与风俗:明代中后期社会变迁的缩影——以浙江余姚江南徐氏为例

明嘉靖万历时浙江绍兴府余姚地区的社会风俗变化很大,并深刻影响到生活方式以及人们的观念。嘉靖时徐天泽将风俗的变化归结为人们的"物欲",在讲求"义"的伦理政治下,"物欲"表现出的"利"对于社会的冲击无疑是巨大的。人们不再安分守己,以满足欲望为追求。余姚江南徐氏在明代由于科举人才辈出,引人注目。地方志从批判的角度记载风俗奢靡,编纂者号召人们移风易俗,反映了地方官的意志以及地方绅士的主张。最值得注意的是,士大夫通过宗族建设来移风易俗,维护社会秩序,造成宗族乡约化,进而组织化。