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Genetic regulation of programmed cell death in Drosophila

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Cell Research 2000年第3期10卷 193-204页

作者： LEE CHENG-YU, ERIC H BAEHRECKE (l Center for Agricultural Biotechnology, University of maryland Biotechnology institute, College Park, maryland 20742,USA Department of Biology, University of maryland, College Park, maryland 20742, USA) CenterforAgriculturalBiotechnology UniversityofMarylandBiotechnologyInstituteDepartmentofBiologyUniversityofMarylandCollegePark20742USA.

Programmed cell death plays an important role in maintaining homeostasis during animal development, and has been conserved in animals as different as nematodes and humans. Recent studies of Drosophila have provided valuable information toward our understanding of genetic regulation of death. Different signals trigger the novel death regulators rpr, hid, and grim, that utilize the evolutionarily conserved iap and ark genes to modulate caspase function. Subsequent removal of dying cells also appears to be accomplished by conserved mechanisms. The similarity between Drosophila and human in cell death signaling pathways illustrate the promise of fruit mes as a model system to elucidate the mechanisms underlying regulation of programmed cell death.

关键词： Apoptosis autophagy phagocytosis development.

An Important Historical Data of Acupuncture in the United States of America

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中国针灸 1995年第S2期15卷 362-363页

作者： Chen Chang(Acupuncture Clinic of maryland,maryland,USA 20852)

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关键词： Acupuncture

Glacial-Interglacial Atmospheric CO_2 Change——The Glacial Burial Hypothesis

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Advances in Atmospheric Sciences 2003年第5期20卷 677-693页

作者： Ning ZENG Department of Meteorology and Earth System Science Interdisciplinary Center, University of maryland, USA Department of Meteorology and Earth System Science Interdisciplinary Center University of Maryland USA

Organic carbon buried under the great ice sheets of the Northern Hemisphere is suggested to be the missing link in the atmospheric CO2 change over the glacial-interglacial cycles. At glaciation, the advancement of continental ice sheets buries vegetation and soil carbon accumulated during warmer periods. At deglaciation, this burial carbon is released back into the atmosphere. In a simulation over two glacial-interglacial cycles using a synchronously coupled atmosphere-land-ocean carbon model forced by reconstructed climate change, it is found that there is a 547-Gt terrestrial carbon release from glacial maximum to interglacial, resulting in a 60-Gt (about 30-ppmv) increase in the atmospheric CO2, with the remainder absorbed by the ocean in a scenario in which ocean acts as a passive buffer. This is in contrast to previous estimates of a land uptake at deglaciation. This carbon source originates from glacial burial, continental shelf, and other land areas in response to changes in ice cover, sea level, and climate. The input of light isotope enriched terrestrial carbon causes atmospheric δ13C to drop by about 0.3‰ at deglaciation, followed by a rapid rise towards a high interglacial value in response to oceanic warming and regrowth on land. Together with other ocean based mechanisms such as change in ocean temperature, the glacial burial hypothesis may offer a full explanation of the observed 80–100-ppmv atmospheric CO2 change.

关键词： atmospheric CO2 ice age glacial burial hypothesis climate

Catastrophe Theory Models for Stress-dependent Behaviour in a NiTi Shape Memory Alloy

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Journal of Materials Science & Technology 1994年第1期10卷 31-33页

作者： Bruce Friedman(Sunrise Enterprises, 1023 Hanson Street, Annapolis, maryland 21403, USA) Sunrise Enterprises Annapolis United States

The measurements by Huibin XU et al of the stress-dependence ot hysteresis in a NiTi shape memo ry alloy are modeled by catastrophe theory. The cusp catastrophe is used with the strain as the behaviour variable and the control parameters being functions of the stress and the temperature. A two constant model is found to be preferred to a four constant model.

关键词： NiTi Catastrophe Theory Models for Stress-dependent Behaviour in a NiTi Shape Memory Alloy

Self-centering seismic retrofit scheme for reinforced concrete frame structures:SDOF system study

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 271-283页

作者： Yunfeng Zhang and Xiaobin Hu Department of Civil and Environmental Engineering,University of maryland,College Park,MD 20742,USA Department of Civil and Environmental Engineering University of Maryland College Park 20742 USA

This paper presents the results of a parametric study of self-centering seismic retrofit schemes for reinforced concrete (RC) frame buildings. The self-centering retrofit system features flag-shaped hysteresis and minimal residual deformation. For comparison purpose,an alternate seismic retrofit scheme that uses a bilinear-hysteresis retrofit system such as buckling-restrained braces (BRB) is also considered in this paper. The parametric study was carried out in a single-degree-of-freedom (SDOF) system framework since a multi-story building structure may be idealized as an equivalent SDOF system and investigation of the performance of this equivalent SDOF system can provide insight into the seismic response of the multi-story building. A peak-oriented hysteresis model which can consider the strength and stiffness degradation is used to describe the hysteretic behavior of RC structures. The parametric study involves two key parameters -the strength ratio and elastic stiffness ratio between the seismic retrofit system and the original RC frame. An ensemble of 172 earthquake ground motion records scaled to the design basis earthquake in California with a probability of exceedance of 10% in 50 years was constructed for the simulation-based parametric study. The effectiveness of the two seismic retrofit schemes considered in this study is evaluated in terms of peak displacement ratio,peak acceleration ratio,energy dissipation demand ratio and residual displacement ratio between the SDOF systems with and without retrofit. It is found from this parametric study that RC structures retrofitted with the self-centering retrofit scheme (SCRS) can achieve a seismic performance level comparable to the bilinear-hysteresis retrofit scheme (BHRS) in terms of peak displacement and energy dissipation demand ratio while having negligible residual displacement after earthquake.

关键词： earthquake reinforced concrete frame structure nonlinear analysis SDOF system seismic retrofit self-centering

ECOLOGICAL CONSEQUENCES OFSOIL EROSION AND SEDIMENTATION

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International Journal of Sediment Research 1999年第2期14卷 355-361页

作者： Grace S. BRUSH (Johns Hopkins University , Baltimore, maryland, USA)

Sediment erosion and siltation in waterways can have ecological consequences as disastrous economically as those related to transport and flooding of adjacent lands. The impact of sediment erosion and deposition on human societies is recorded in many historical documents. The paleoecological record also provides evidence of the long-term effects of siltation. Sedimentation rates in the Chesapeake Bay estuary, in mid-Atlantic USA, have doubled and quadrupled over the last 200 to 300 years with the initiation and intensification of agriculture. The result has been filling in of many estuarine tributaries and the transformation of the estuary from a benthic to a planktonic ecosystem. This change took place as light became limiting in the water column and benthic plants could no longer photosynthesize, resulting in a proliferation of planktonic algae. Planktonic algal growth was also fueled by fertilizers attached to eroded soil particles. leading ultimately to eutrophication within the water column and anoxia of the bottom waters.

关键词： Sedimentation Civilizations Land use Sediment cores

Co-monitoring bacterial and dinoflagellates communities by denaturing gradient gel electrophoresis (DGGE) and SSU rRNA sequencing during a dinoflagellates bloom

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Acta Oceanologica Sinica 2004年第3期23卷 483-492页

作者： KANJinjun CHENFeng CenterofMarineBiotechnology UniversityofMarylandBiotechnologyInstituteBaltimoreMD21202

Dinoflagellates are unicellular eukaryotic protists that dominate in all coastal waters, and are also present in oceanic waters. Despite the central importance of dinoflagellates in global primary production, the relationship between dinoflagellates and bacteria are still poorly understood. In order to understand the ecological interaction between bacterial and dinoflagellates communities, denaturing gradient gel electrophoresis (DGGE) and SSU rRNA sequencing were applied to monitoring the population dynamics of bacteria and dinoflagellates from the onset to disappearance of a dinoflagellates bloom occurred in Baltimore Inner Harbor, from April 15 to 24,2002. Although Prorocentrum minimum was the major bloom forming species under the light microscopy, DGGE method with dinoflagellate specific primers demonstrated that Prorocentrum micans, Gymnodinium galatheanum and Gyrodinium uncatenum were also present during the bloom. Population shifts among the minor dinoflagellate groups were observed. DGGE of PCR-amplified 16S rRNA gene fragments indicated that cyanobacteria, α, β, γ-proteobacteria, Flavobacterium Bacteroides-Cytophaga (FBC), and Planctomcetes were the major components of bacterial assemblages during the bloom. DGGE analysis showed that Cytophagales and α-proteobacteria played important roles at different stages of dinoflagellates bloom. DGGE can be used as a rapid tool to simultaneously monitor population dynamics of both bacterial and dinoflagellates communities in aquatic environments, which is demonstrated here.

关键词： bacteria dinoflagellates DGOE SSU rDNA sequencing

INTRODUCTION TO THIS ISSUE

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当代外语研究 2012年第12期 4-5+124页

作者： NAN JIANG University of maryland University of maryland

The field of Second Language Studies has gone through a period of rapid development since the 1980s. This development can be seen in the ever expanding scope of research,in the increasing amount of research output,and... 详细信息

关键词： INTRODUCTION TO THIS ISSUE

TWO-PHOTON ENTANGLEMENT AND QUANTUM REALITY

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TWO-PHOTON ENTANGLEMENT AND QUANTUM REALITY