^226Ra evidence for the ecosystem shift over the past 40 years in the North Pacific Subtropical Gyre

Surface seawater was collected for ~(226)Ra measurement in the North Pacific Subtropical Gyre from July to October, 1999 and October to December, 2003. Combined with the historical data reported for this sea area, a declined trend of surface ~(226)Ra concentrations was observed since 1960s, indicating the ecosystem shift in response to global warming. On one side, the enhanced stratification of the upper water column resulting from global warming reduced the ~(226)Ra input from the depth, on the other, the temporal increase of biological production resulting from the climate-related ecosystem structure change strengthened the ~(226)Ra removal from the surface ocean. Both the physical and biological processes resulted in the decrease of surface ~(226)Ra concentrations in the North Pacific Subtropical Gyre. The temporal trend of surface ~(226)Ra concentrations was consistent with the trends of chlorophyll a, silicate, phosphate and primary production previously reported. This study provided ~(226)Ra evidence for the ecosystem shift under global change.     

How physics flew the philosophers' nest

We all know that, nowadays, physics and philosophy are housed in separate departments on university campuses. They are distinct disciplines with their own journals and conferences, and in general they are practiced by different people, using different tools and methods. We also know that this was not always the case: up until the early 17th century (at least), physics was a part of philosophy. So what happened? And what philosophical lessons should we take away? We argue that the split took place long after Newton's Principia (rather than before, as many standard accounts would have it), and offer a new account of the philosophical reasons that drove the separation. We argue that one particular problem, dating back to Descartes and persisting long into the 18th century, played a pivotal role. The failure to solve it, despite repeated efforts, precipitates a profound change in the relationship between physics and philosophy. The culprit is the problem of collisions. Innocuous though it may seem, this problem becomes the bellwether of deeper issues concerning the nature and properties of bodies in general. The failure to successfully address the problem led to a reconceptualization of the goals and subject-matter of physics, a change in the relationship between physics and mechanics, and a shift in who had authority over the most fundamental issues in physics.     

The mean residence time of river water in the Canada Basin

Seawater was collected from the western Arctic Ocean for measurements of 18О, ^226Ra and ^228Ra. The fractions of river runoff and sea ice melt-water in water samples were estimated by using δ^18О-S-PО^＊ tracer system. The mean residence time of river water in the Canada Basin was calculated based on the relationship between ^228Ra/^226Ra）A.R. and the fractions of river runoff in the shelf and deep ocean. Our results showed that the river runoff fractions in the Canada Basin were significantly higher than those in the shelf regions, suggesting that the Canada Basin is a major storage region for Arctic river water. ^228Ra activity concentrations in the Chukchi shelf and the Beaufort shelf ranged from 0.16 to 1.22 Bq/m^3, lower than those reported for shelves in the low and middle latitudes, indicating the effect of sea ice melt-water. A good positive linear relationship was observed between ^228Ra/^226Ra）A.R. and the fraction of river runoff for shelf waters, while the ^228Ra/^226Ra）A.R. in the Canada Basin was located below this re-gressive line. The low ^228Ra/^226Ra）A.R. in the Canada Basin was ascribed to ^228Ra decay during shelf wa-ters transporting to the deep ocean. The residence time of 5.0-11.0 a was estimated for the river water in the Canada Basin, which determined the time response of surface freshening in the North Atlantic to the river runoff into the Arctic Ocean.     

CD226分子siRNA慢病毒载体的构建和鉴定

为设计筛选针对人CD226分子的siRNA序列,构建相应的siRNA慢病毒载体,检测其对Jurkat/E6细胞膜表面天然CD226分子表达水平的影响,首先设计并合成4对siRNA双链寡聚核苷酸,与CD226分子真核表达载体共同转染293T细胞,挑选出最有效抑制CD226表达的序列。应用基因工程技术,将该序列连接于慢病毒载体pLKO.1中,构建携带针对目的基因CD226的siRNA慢病毒载体。使用慢病毒包装质粒混合物和构建好的慢病毒载体共转染293T细胞,收集上清,感染Jurkat/E6细胞系,对病毒感染效果进行检测。结果在4条针对CD226分子设计的siRNA序列中,siRNA—513最为有效的抑制了外源性CD226分子的表达,带有该序列的慢病毒载体pLKO—CD226可以完全抑制Jurkat/E6细胞上天然分子的表达。说明应用基因工程技术成功构建了针对CD226分子的RNA干扰慢病毒载体,为深入研究人类黏附分子CD226在机体免疫功能方面提供了技术支持。     

Émilie Du Châtelet's interpretation of the laws of motion in the light of 18th century mechanics

Émilie Du Châtelet is well known for her French translation of Newton's Philosophiae Naturalis Principia Mathematica. It is the first and only French translation of Newton's magnum opus. The complete work appeared in 1759 under the title Principes mathématiques de la philosophie naturelle, par feue Madame la Marquise Du Chastellet. Before translating Newton's Principia, Du Châtelet worked on her Institutions de physique. In this book she defended the Leibnizian concept of living forces – vis viva. This paper argues that both of these works were part of a critical transformation and consolidation of post-Newtonian mechanics in the early 18th century, beyond Newton and Leibniz. This will be shown by comparing Du Châtelet's translation of Newton's axioms with her own formulations of the laws of motion in light of Thomas Le Seur's and François Jacquier's Geneva edition which holds a special place among the several editions of the Principia that appeared in the early 18th century.     

Mobile SVG在手机游戏中的应用研究

无线应用领域是当前的一大热点,为了可以解决光栅格式图形存在的失真等问题,研究了Mobile SVG技术在无线应用中的图形处理优势,阐述了如何在J2ME平台中使用Mobile SVG技术,然后使用JSR-226开发了一个弹球游戏,为无线游戏开发提供了一个参考思路。     

微量镭在海泡石矿物上的吸附行为

研究了海泡石粘土矿物对水中微量镭的吸附行为,讨论了海泡石吸附镭的影响因素及吸附机理.结果表明,天然海泡石矿物对镭有一定吸附作用,其吸附分配系数Kd值为9.1×103mL/g.     

精神分裂症患者T淋巴细胞上CD226分子的表达研究

目的 通过检测T细胞上CD226分子的表达情况来阐明SCH患者T细胞的活化状态及功能．方法 将精神分裂症患者和正常对照群的外周血单个核细胞各分为植物血凝素(PHA)刺激组与非刺激组,用双色免疫荧光染色和流式细胞术检测T细胞上CD226分子的表达百分率,观察PHA刺激对T细胞表达CD226的影响．结果 1)无论是否给予PHA刺激,SCH患者外周血T淋巴细胞上CD226阳性百分率均显著高于正常对照组．2)给予PHA刺激后,SCH患者和正常对照者外周血T淋巴细胞上CD226分子的表达均显著增高;在升高幅度上,SCH患者CD226表达增长值显著低于正常对照组．3)在患者与对照组二者之间,未发现CD4,CD8 2个T细胞亚群之间CD226表达百分率存在显著性差异．4)精神分裂症患者CD226的表达与性别无关．结论 SCH患者外周血T淋巴细胞上CD226分子的表达百分率显著升高,细胞敏感性增强．在SCH患者体内。大量T淋巴细胞已处于活化状态．SCH患者体内存在某种非正常刺激因素。