Characteristics of distribution and seasonal variation of aerosol optical depth in eastern China with MODIS products

The accuracy of MODIS aerosol products from the NASA Terra Satellite is validated in comparison with the results of sun-photometer observations in Beijing and Hong Kong. By analyzing the MODIS aerosol products within the period of August 2000 to April 2003, it is believed that human activities are the main source of aerosols in the eastern part of China. This is based on the facts that all areas with relatively high values are consistent with regions of dense population and fast economic development, such as the North China Plain, the Sichuan Basin and the Pearl River Delta. It is also supported by the distribution of 舗gstr鰉 exponents showing that most aerosols in the eastern part of China are closely related to human activities, excepting the strong sandstorm episodes occurring in spring, fall and winter. In contrast to developed countries, the 舗gstr鰉 exponent of urban area in China is lower than its surroundings, indicating that the contribution of local floating dust and soot attributed to human activities is significant. Results presented in this paper provide important data for further research on climatic change and environmental study.     

MODIS气溶胶光学厚度产品在地面PM_(10)监测方面的应用研究

利用MODIS(中分辨率成像光谱仪)两年的气溶胶光学厚度(AOD)产品与北京地区API转化得到的PM10质量浓度、北京大学站点直接监测的PM10质量浓度以及香港元朗站点监测的PM10质量浓度做相关性分析,发现二者的直接相关程度较低。将AOD除以气溶胶季节标高,得到地面消光系数,与地面PM10质量浓度相关性提高。对地面消光系数进行相对湿度订正,得到计算的质量浓度,与地面实际观测的PM10质量浓度相关性进一步提高。经过两年时间资料的对比分析,证实气溶胶遥感光学厚度经过垂直和湿度影响订正后,可以应用于地面PM10监测。     

Lgr5 homologues associate with Wnt receptors and mediate R-spondin signalling

The adult stem cell marker Lgr5 and its relative Lgr4 are often co-expressed in Wnt-driven proliferative compartments. We find that conditional deletion of both genes in the mouse gut impairs Wnt target gene expression and results in the rapid demise of intestinal crypts, thus phenocopying Wnt pathway inhibition. Mass spectrometry demonstrates that Lgr4 and Lgr5 associate with the Frizzled/Lrp Wnt receptor complex. Each of the four R-spondins, secreted Wnt pathway agonists, can bind to Lgr4, -5 and -6. In HEK293 cells, RSPO1 enhances canonical WNT signals initiated by WNT3A. Removal of LGR4 does not affect WNT3A signalling, but abrogates the RSPO1-mediated signal enhancement, a phenomenon rescued by re-expression of LGR4, -5 or -6. Genetic deletion of Lgr4/5 in mouse intestinal crypt cultures phenocopies withdrawal of Rspo1 and can be rescued by Wnt pathway activation. Lgr5 homologues are facultative Wnt receptor components that mediate Wnt signal enhancement by soluble R-spondin proteins. These results will guide future studies towards the application of R-spondins for regenerative purposes of tissues expressing Lgr5 homologues.     

Use of Data Mining to Support the Development of Knowledge Intensive CAD

In order to compete in the global manufacturing mar ke t, agility is the only possible solution to response to the fragmented market se gments and frequently changed customer requirements. However, manufacturing agil ity can only be attained through the deployment of knowledge. To embed knowledge into a CAD system to form a knowledge intensive CAD (KIC) system is one of way to enhance the design compatibility of a manufacturing company. The most difficu lt phase to develop a KIC system is to capitalize a ...     

南海台风"悟空2000"生成及发展的数值模拟

应用NCAR/PSU中尺度非静力模式MM5模拟了南海台风"悟空2000"从一个热带扰动发展为强台风的过程。模拟结果表明,MM5模式能够很好地模拟出"悟空2000"台风的强度和最大风速,清晰显示出南海台风发展中具有的阶段性和爆发性。从水汽和位涡等诊断量的分析出发,分析了模拟的台风结构和台风眼生成的可能影响因素。敏感性试验结果显示,南海海面温度对台风发生发展有至关重要的作用:如果海表温度降低1℃,模拟的台风最大风速将降低近10m/s,风速达到台风级别(32.8m/s)的时间推迟约7个小时;如果海表温度降低2℃(SST仍高于26.5℃),该热带扰动将不能发展到台风的强度。     

Systematic identification of genomic markers of drug sensitivity in cancer cells

Clinical responses to anticancer therapies are often restricted to a subset of patients. In some cases, mutated cancer genes are potent biomarkers for responses to targeted agents. Here, to uncover new biomarkers of sensitivity and resistance to cancer therapeutics, we screened a panel of several hundred cancer cell lines--which represent much of the tissue-type and genetic diversity of human cancers--with 130 drugs under clinical and preclinical investigation. In aggregate, we found that mutated cancer genes were associated with cellular response to most currently available cancer drugs. Classic oncogene addiction paradigms were modified by additional tissue-specific or expression biomarkers, and some frequently mutated genes were associated with sensitivity to a broad range of therapeutic agents. Unexpected relationships were revealed, including the marked sensitivity of Ewing's sarcoma cells harbouring the EWS (also known as EWSR1)-FLI1 gene translocation to poly(ADP-ribose) polymerase (PARP) inhibitors. By linking drug activity to the functional complexity of cancer genomes, systematic pharmacogenomic profiling in cancer cell lines provides a powerful biomarker discovery platform to guide rational cancer therapeutic strategies.     

Subnanometre-resolution structure of the intact Thermus thermophilus H+-driven ATP synthase

Ion-translocating rotary ATPases serve either as ATP synthases, using energy from a transmembrane ion motive force to create the cell's supply of ATP, or as transmembrane ion pumps that are powered by ATP hydrolysis. The members of this family of enzymes each contain two rotary motors: one that couples ion translocation to rotation and one that couples rotation to ATP synthesis or hydrolysis. During ATP synthesis, ion translocation through the membrane-bound region of the complex causes rotation of a central rotor that drives conformational changes and ATP synthesis in the catalytic region of the complex. There are no structural models available for the intact membrane region of any ion-translocating rotary ATPase. Here we present a 9.7?? resolution map of the H(+)-driven ATP synthase from Thermus thermophilus obtained by electron cryomicroscopy of single particles in ice. The 600-kilodalton complex has an overall subunit composition of A(3)B(3)CDE(2)FG(2)IL(12). The membrane-bound motor consists of a ring of L subunits and the carboxy-terminal region of subunit I, which are equivalent to the c and a subunits of most other rotary ATPases, respectively. The map shows that the ring contains 12 L subunits and that the I subunit has eight transmembrane helices. The L(12) ring and I subunit have a surprisingly small contact area in the middle of the membrane, with helices from the I subunit making contacts with two different L subunits. The transmembrane helices of subunit I form bundles that could serve as half-channels across the membrane, with the first half-channel conducting protons from the periplasm to the L(12) ring and the second half-channel conducting protons from the L(12) ring to the cytoplasm. This structure therefore suggests the mechanism by which a transmembrane proton motive force is converted to rotation in rotary ATPases.     

Sister chromatid differential staining pattern in prematurely condensed chromosomes

Summary Application of sister chromatid differential (SCD) procedure on G₁, S and G₂ prematurely condensed chromosomes (PCC) of cells in the second and third cycle of DNA replication in medium containing BrdU reveals differential staining patterns characteristic of their respective stages in the cell cycle. These findings also suggest a structural similarity between PCC and metaphase chromosomes.Supported in part by grants from the National Foundation-March of Dimes (grant No. 1-327) and from the National Cancer Institute (grant No. CA-16480).     

A comparative study of the gastric ulcerogenic effects of stress and reserpine in rats with decreased stomach wall mast cell populations

Summary Stress-induced gastric glandular ulcers in rats appeared less severe than those evoked by reserpine, although glandular mucosal mast cell counts were equally decreased. Prior depletion of the glandular mucosal mast cell population confirmed the hypothesis that an additional mechanism contributes to reserpine ulceration.     

Acetaldehyde oxidation inDrosophila null-mutants for alcohol dehydrogenase

Summary Aldehyde dehydrogenase (ALDH) activity is demonstrated in four strains ofD. melanogaster lacking active alcohol dehydrogenase (ADH-null mutants). In the four strains, ALDH activities are similar to those found in a wild strain. It is concluded that ADH-null flies are able to detoxify acetaldehyde. This finding is discussed in relation with the dual function of ADH proposed recently.This work was supported by a grant from the Medical Research Council of Canada (MRC 6920) to Dr F. Garcin.