A green algal apicoplast ancestor     

Funes S  Davidson E  Reyes-Prieto A  Magallón S  Herion P  King MP  González-Halphen D 《Science (New York, N.Y.)》2002,298(5601):2155

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Nanocapillarity and Chemistry in Carbon Nanotubes     

D Ugarte  A Chatelain  de Heer WA 《Science (New York, N.Y.)》1996,274(5294):1897-1899

Open carbon nanotubes were filled with molten silver nitrate by capillary forces. Only those tubes with inner diameters of 4 nanometers or more were filled, suggesting a capillarity size dependence as a result of the lowering of the nanotube-salt interface energy with increasing curvature of the nanotube walls. Nanotube cavities should also be less chemically reactive than graphite and may serve as nanosize test tubes. This property has been illustrated by monitoring the decomposition of silver nitrate within nanotubes in situ in an electron microscope, which produced chains of silver nanobeads separated by high-pressure gas pockets.  相似文献   

The premetazoan ancestry of cadherins     

Abedin M  King N 《Science (New York, N.Y.)》2008,319(5865):946-948

Cadherin-mediated cell adhesion and signaling is essential for metazoan development and yet is absent from all other multicellular organisms. We found cadherin genes at numbers similar to those observed in complex metazoans in one of the closest single-celled relatives of metazoans, the choanoflagellate Monosiga brevicollis. Because the evolution of metazoans from a single-celled ancestor required novel cell adhesion and signaling mechanisms, the discovery of diverse cadherins in choanoflagellates suggests that cadherins may have contributed to metazoan origins.  相似文献   

Ice flow direction change in interior West Antarctica     

Siegert MJ  Welch B  Morse D  Vieli A  Blankenship DD  Joughin I  King EC  Vieli GJ  Payne AJ  Jacobel R 《Science (New York, N.Y.)》2004,305(5692):1948-1951

Upstream of Byrd Station (West Antarctica), ice-penetrating radar data reveal a distinctive fold structure within the ice, in which isochronous layers are unusually deep. The fold has an axis more than 50 kilometers long, which is aligned up to 45 degrees to the ice flow direction. Although explanations for the fold's formation under the present flow are problematic, it can be explained if flow was parallel to the fold axis approximately 1500 years ago. This flow change may be associated with ice stream alterations nearer the margin. If this is true, central West Antarctica may respond to future alterations more than previously thought.  相似文献   

Widespread intense turbulent mixing in the Southern Ocean     

Garabato AC  Polzin KL  King BA  Heywood KJ  Visbeck M 《Science (New York, N.Y.)》2004,303(5655):210-213

Observations of internal wave velocity fluctuations show that enhanced turbulent mixing over rough topography in the Southern Ocean is remarkably intense and widespread. Mixing rates exceeding background values by a factor of 10 to 1000 are common above complex bathymetry over a distance of 2000 to 3000 kilometers at depths greater than 500 to 1000 meters. This suggests that turbulent mixing in the Southern Ocean may contribute crucially to driving the upward transport of water closing the ocean's meridional overturning circulation, and thus needs to be represented in numerical simulations of the global ocean circulation and the spreading of biogeochemical tracers.  相似文献   

Breast and ovarian cancer risks due to inherited mutations in BRCA1 and BRCA2     

King MC  Marks JH  Mandell JB;New York Breast Cancer Study Group 《Science (New York, N.Y.)》2003,302(5645):643-646

Risks of breast and ovarian cancer were determined for Ashkenazi Jewish women with inherited mutations in the tumor suppressor genes BRCA1 and BRCA2. We selected 1008 index cases, regardless of family history of cancer, and carried out molecular analysis across entire families. The lifetime risk of breast cancer among female mutation carriers was 82%, similar to risks in families with many cases. Risks appear to be increasing with time: Breast cancer risk by age 50 among mutation carriers born before 1940 was 24%, but among those born after 1940 it was 67%. Lifetime risks of ovarian cancer were 54% for BRCA1 and 23% for BRCA2 mutation carriers. Physical exercise and lack of obesity in adolescence were associated with significantly delayed breast cancer onset.  相似文献   

Issues in biosecurity and biosafety     

Cook-Deegan RM  Berkelman R  Davidson EM  Finder S  Heitman E  Kelley MC  King NM  Moseley R  Thomas JC  Tilden SJ  Vangsnes NM 《Science (New York, N.Y.)》2005,308(5730):1867-1868

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Mossbauer investigation of shocked and unshocked iron meteorites and fayalite     

Lafleur LD  Goodman CD  King EA 《Science (New York, N.Y.)》1968,162(3859):1268-1270

M?ssbauer spectra of several iron meteorites have been measured by a resonant scattering technique rather than by the conventional transmission method, thereby eliminating the necessity for the preparation of thin samples. No significant differences were observed in the spectra of specimens of mechanically deformed, shocked, and unshocked iron meteorites, nor in the absorption spectra of artificially shocked and unshocked fayalite.  相似文献   

PHYSICO-CHEMICAL BASIS OF PSYCHIC PHENOMENA     

Hughes JS  King HH 《Science (New York, N.Y.)》1923,57(1481):590-591

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Seasonal speedup along the western flank of the Greenland Ice Sheet   总被引：1，自引：0，他引：1  

Joughin I  Das SB  King MA  Smith BE  Howat IM  Moon T 《Science (New York, N.Y.)》2008,320(5877):781-783

It has been widely hypothesized that a warmer climate in Greenland would increase the volume of lubricating surface meltwater reaching the ice-bedrock interface, accelerating ice flow and increasing mass loss. We have assembled a data set that provides a synoptic-scale view, spanning ice-sheet to outlet-glacier flow, with which to evaluate this hypothesis. On the ice sheet, these data reveal summer speedups (50 to 100%) consistent with, but somewhat larger than, earlier observations. The relative speedup of outlet glaciers, however, is far smaller (<15%). Furthermore, the dominant seasonal influence on Jakobshavn Isbrae's flow is the calving front's annual advance and retreat. With other effects producing outlet-glacier speedups an order of magnitude larger, seasonal melt's influence on ice flow is likely confined to those regions dominated by ice-sheet flow.  相似文献