Environmental factors regulating cyanobacteria dominance and microcystin production in a subtropical lake within the Taihu watershed, China

Understanding the pattern of phytoplankton and their dependence on water quality variables, can help the management of eutrophic lakes. The aim of this study was to determine water quality and environmental factors associated with cyanobacteria dominance and microcystin production in Qingshan Lake, a subtropical lake located in the headwater of the Taihu watershed, China. Water samples collected monthly from 10 study sites in Qingshan Lake were analyzed for the species distributions of freshwater algae and physico-chemical parameters including total nitrogen (TN), ammonia (NH₄ ⁺-N), nitrate (NO₃ ⁻-N), total phosphorus (TP), and chlorophyll a (Chl-a) from June, 2008 to May, 2009. Qingshan Lake was found to be eutrophic, based on the calculated trophic state index (TSI). The average TN of 4.33 mg/L during the study period exceeded the Surface Water Quality Standards of China. TP was significantly correlated with relative abundance of cyanobacteria and Microcystis biovolume, indicating its important role in regulating cyanobacteria. Microcystis, Anabaena, and Oscillatoria were dominant cyanobacteria in Qingshan Lake from June to November, 2008. Cyanobacteria dominance was regulated by water temperature and TP. Principal component analysis further indicated that microcystin production was most affected by water temperature, TP, and cyanobacteria biomass. Results suggest that the control of TP in summer can mitigate cyanobacteria dominance and microcystin production in Qingshan Lake, and close monitoring should be undertaken in summer.     

The impact of charter schools on the efficiency of traditional public schools: Evidence from Michigan

This paper examines the competitive effects of charter schools on the efficiency of traditional public schools. The analysis utilizes a statewide school-level longitudinal dataset of Michigan schools from 1994 to 2004. Fixed effect and two alternative estimation methods are employed. Overall, the results suggest that charter competition had a negative impact on student achievement and school efficiency in Michigan's traditional public schools. The effect is small or negligible in the short run, but becomes more substantial in the long run.     

浅析争议的美国同性婚姻合法化问题

本论文旨在讨论当代美国极具争议的一个社会问题,即同性婚姻是否应该合法化。关于同性婚姻是否应该合法化的争论存在反对和支持两种情形。反对者认为同性婚姻是不道德的,是对婚姻制度的破坏,同时对孩子和社会也会造成危害。支持者的观点可概括为:婚姻权利是人的基本权利,可以自由选择;禁止同性婚姻是一种歧视;根据当前美国联邦政府和各州关于同性婚姻的立法现状,美国同性婚姻合法化议题仍将是一个未知数,需要进一步探讨。     

独立董事制度刍议

独立董事制度对完善我国上市公司的治理结构十分必要,但中国特有的股权现象以及传统观念、法思想都使得独立董事在中国水土不服,较多成为公司合法性的摆设。本文论述了独立董事制度起源以及重要性,提出加快独立董事职业化建设,完善独立董事法律法规体系,令其循着科学的轨道运行。     

一个vr应用系统的方案设计

根据目前市场上电子宠物都是二维单色液晶屏幕显示,感觉比较枯燥,因此想要设计一种虚拟宠物.本篇文章主要讨论虚拟宠物的基本原理,实现的主要技术,设计思想以及实现它所需的设备和软、硬件条件.     

理想与现实碰撞下的现代人

《兔子快跑》是约翰·厄普代克“兔子四部曲”的第一部。这部小说刻画哈里·安斯特朗在理想与现实之间碰撞与冲突下的失意与逃避,阐释兔子消极地逃避现实来寻求幻想、寻找自我,宛如镜中花、水中月,华而不实,一触即破。     

心灵荒漠的悲歌

《维莱特》是夏洛蒂·勃朗特的一本自传体心理小说。根据弗洛伊德的理论，这本小说是作者压抑情感的一种外化形式。作者创造了一个倍受压抑的女主角露西。她心灵的压抑，不仅来自于她内在的“理智”，还来源于整个社会的外在压迫。在“压抑”的束缚之下，露西悲观绝望，被动地承受着命运安排给她的一切，丧失了行动的权利。她没有勇气去追逐自己的幸福，哪怕是自己渴望已久的爱情。“压抑”好比一个牢笼，监禁了露西所有的梦想和希望。     

马克思主义文化观的基本内涵—兼论“突厥文化共同论”的民族分裂主义文化观的反动本质

从19世纪初叶起,随着泛厥主义和泛伊斯兰主义传入新疆,受化泛突厥主义思想影响,并在其理论基础上,由新老民族分裂主义分子经过长期反动思想理论宣传,形成了“突厥化共同体论”的民族分裂主义化观,它不仅和马克思主义化观完全对立,而且在理论和史实上是根本站不住脚的,是为分裂主义政治目的服务的腐配没落的剥削阶级反动思想。     

基于VRML技术的虚拟实验室的设计与实现

虚拟实验有助于提高学生的自主学习兴趣、创新能力、实际动手能力和综合素质。针对实验教学的特点,对基于VRML技术的虚拟实验系统进行功能分析和结构设计,并对虚拟模型的建立和优化、虚拟实验中的交互以及交互过程中对数据库的访问等关键技术进行研究。实践证明,基于VRML的虚拟实验系统是切实有效的。     

开源软件在我国推广的机遇、挑战及其使命

本文分析了开源软件在我国推广的机遇及面临的挑战,提出了在我国推广开源软件的使命。