Rise of the Andes     

Garzione CN  Hoke GD  Libarkin JC  Withers S  MacFadden B  Eiler J  Ghosh P  Mulch A 《Science (New York, N.Y.)》2008,320(5881):1304-1307

The surface uplift of mountain belts is generally assumed to reflect progressive shortening and crustal thickening, leading to their gradual rise. Recent studies of the Andes indicate that their elevation remained relatively stable for long periods (tens of millions of years), separated by rapid (1 to 4 million years) changes of 1.5 kilometers or more. Periodic punctuated surface uplift of mountain belts probably reflects the rapid removal of unstable, dense lower lithosphere after long-term thickening of the crust and lithospheric mantle.  相似文献   

How much more global warming and sea level rise?     

Meehl GA  Washington WM  Collins WD  Arblaster JM  Hu A  Buja LE  Strand WG  Teng H 《Science (New York, N.Y.)》2005,307(5716):1769-1772

Two global coupled climate models show that even if the concentrations of greenhouse gases in the atmosphere had been stabilized in the year 2000, we are already committed to further global warming of about another half degree and an additional 320% sea level rise caused by thermal expansion by the end of the 21st century. Projected weakening of the meridional overturning circulation in the North Atlantic Ocean does not lead to a net cooling in Europe. At any given point in time, even if concentrations are stabilized, there is a commitment to future climate changes that will be greater than those we have already observed.  相似文献   

How farmers matter in shaping agricultural technologies: social and structural characteristics of wheat growers and wheat varieties     

Leland L. Glenna  Raymond A. JussaumeJr.  Julie C. Dawson 《Agriculture and Human Values》2011,28(2):213-224

Science and technology studies (STS) research challenges the concept of technological determinism by investigating how the end users of a technology influence that technology’s trajectory. STS critiques of determinism are needed in studies of agricultural technology. However, we contend that focusing on the agency of end users may mask the role of political-economic factors which influence technology developments and applications. This paper seeks to mesh STS insights with political-economic perspectives by accounting for relationships between availability of diverse technologies, variations in political-economic structures, and farmer interests and characteristics. We present the results of an analysis on the recent development of three wheat varieties: (a) a wheat variety that was modified genetically to tolerate the herbicide glyphosate, (b) wheat varieties with characteristics selected to serve specific markets, (c) and emerging research and development of perennial wheat varieties. Using data obtained through a survey of wheat growers in Washington State, we analyzed whether farmer interest in these three clusters of wheat varieties was associated with distinct individual characteristics and attitudes and whether those characteristics and attitudes are consistent with political economic structures. Although our analysis did not allow us to assess the degree of direct influence that farmers have on the technological development trajectory for these types of wheat, we were able to document variation in technological alternatives and farmer characteristics related to different political-economic trends.  相似文献   

Little evidence for developmental plasticity of adult hematopoietic stem cells     

Wagers AJ  Sherwood RI  Christensen JL  Weissman IL 《Science (New York, N.Y.)》2002,297(5590):2256-2259

To rigorously test the in vivo cell fate specificity of bone marrow (BM) hematopoietic stem cells (HSCs), we generated chimeric animals by transplantation of a single green fluorescent protein (GFP)-marked HSC into lethally irradiated nontransgenic recipients. Single HSCs robustly reconstituted peripheral blood leukocytes in these animals, but did not contribute appreciably to nonhematopoietic tissues, including brain, kidney, gut, liver, and muscle. Similarly, in GFP+:GFP- parabiotic mice, we found substantial chimerism of hematopoietic but not nonhematopoietic cells. These data indicate that "transdifferentiation" of circulating HSCs and/or their progeny is an extremely rare event, if it occurs at all.  相似文献   

Dietary restriction and life-span     

Bartke A  Wright JC  Mattison JA  Ingram DK  Miller RA  Roth GS 《Science (New York, N.Y.)》2002,296(5576):2141-2; author reply 2141-2

  相似文献   

水分胁迫对番茄叶片气孔传导及光合色素的影响   总被引：11，自引：1，他引：11  

程智慧  孟焕文  Stephen A Rolfe 《西北农林科技大学学报(自然科学版)》2002,30(6):93-96

以栽培番茄品种AilsaCraig的6叶期幼苗为试验材料,在水培条件下研究了50,75和100g/LPEG水分胁迫对叶片气孔传导、光合色素含量及发叶速度的影响。结果表明,水分胁迫使气孔传导度和发叶速度降低,光合色素增加。气孔传导度和发叶速度的降低均与水分胁迫强度和持续时间有关,而光合色素的增加主要与胁迫持续时间有关。  相似文献   

Viral IL-6-induced cell proliferation and immune evasion of interferon activity     

Chatterjee M  Osborne J  Bestetti G  Chang Y  Moore PS 《Science (New York, N.Y.)》2002,298(5597):1432-1435

  相似文献   

Functional links between Aβ toxicity, endocytic trafficking, and Alzheimer's disease risk factors in yeast     

Treusch S  Hamamichi S  Goodman JL  Matlack KE  Chung CY  Baru V  Shulman JM  Parrado A  Bevis BJ  Valastyan JS  Han H  Lindhagen-Persson M  Reiman EM  Evans DA  Bennett DA  Olofsson A  DeJager PL  Tanzi RE  Caldwell KA  Caldwell GA  Lindquist S 《Science (New York, N.Y.)》2011,334(6060):1241-1245

Aβ (beta-amyloid peptide) is an important contributor to Alzheimer's disease (AD). We modeled Aβ toxicity in yeast by directing the peptide to the secretory pathway. A genome-wide screen for toxicity modifiers identified the yeast homolog of phosphatidylinositol binding clathrin assembly protein (PICALM) and other endocytic factors connected to AD whose relationship to Aβ was previously unknown. The factors identified in yeast modified Aβ toxicity in glutamatergic neurons of Caenorhabditis elegans and in primary rat cortical neurons. In yeast, Aβ impaired the endocytic trafficking of a plasma membrane receptor, which was ameliorated by endocytic pathway factors identified in the yeast screen. Thus, links between Aβ, endocytosis, and human AD risk factors can be ascertained with yeast as a model system.  相似文献   

Larval performances and life cycle completion of the Siberian moth, <Emphasis Type="Italic">Dendrolimus sibiricus</Emphasis> (Lepidoptera: Lasiocampidae), on potential host plants in Europe: a laboratory study on potted trees     

Natalia Kirichenko  Julie Flament  Yuri Baranchikov  Jean-Claude Grégoire 《European Journal of Forest Research》2011,130(6):1067-1074

The Siberian moth, Dendrolimus sibiricus, Tschtv. is the most harmful defoliator of coniferous forests in North Asia. The pest has already spread over the Urals and continues moving westwards. Recently, it has been recommended for quarantine in member countries by European and Mediterranean Plant Protection Organization (EPPO). The performances of the pest on coniferous species planted in Europe were assessed on a range of potted trees corresponding to the spectrum of economically important conifers in the EU: European larch Larix decidua, Norway spruce Picea abies, Scots pine Pinus sylvestris, European black pine Pinus nigra, and the North American species: Douglas fir Pseudotsuga menziesii and grand fir Abies grandis. Larvae showed a potential to survive and complete the development on all these host tree species. Favorable hosts were grand fir, European larch, and Douglas fir that allowed higher survival, better larval development, and as a result, yielded heavier pupae and adult moths with higher longevity. Black pine was a poor host but, however, could still support larval and pupal development. Norway spruce and Scots pine had an intermediate behavior. If accidentally introduced to Europe, the Siberian moth may become especially damaging in forest stands predominated by European larch and by the North American firs. Norway spruce and especially the two-needle pines will be less prone to intensive defoliation by this species. The fact that the pest may damage the range of economically important coniferous species should be taken into account in the pest risk assessment for Europe and also for North America where the Siberian moth occurrence is considered likely.  相似文献   

Feline cholangitis: a necropsy study of 44 cats (1986-2008)     

Callahan Clark JE  Haddad JL  Brown DC  Morgan MJ  Van Winkle TJ  Rondeau MP 《Journal of Feline Medicine and Surgery》2011,13(8):570-576

  相似文献