A new type of meteoritic diamond in the enstatite chondrite abee     

Russell SS  Pillinger CT  Arden JW  Lee MR  Ott U 《Science (New York, N.Y.)》1992,256(5054):206-209

Diamonds with delta(13)C values of -2 per mil and less than 50 parts per million (by mass) nitrogen have been isolated from the Abee enstatite chondrite by the same procedure used for concentrating Cdelta, the putative interstellar diamond found ubiquitously in primitive meteorites and characterized by delta(13)C values of -32 to -38 per mil, nitrogen concentrations of 2,000 to 12,500 parts per million, and delta(15)N values of -340 per mil. Because the Abee diamonds have typical solar system isotopic compositions for carbon, nitrogen, and xenon, they are presumably nebular in origin rather than presolar. Their discovery in an unshocked meteorite eliminates the possibility of origins normally invoked to account for diamonds in ureilites and iron meteorites and suggests a low-pressure synthesis. The diamond crystals are approximately 100 nanometers in size, are of an unusual lath shape, and represent approximately 100 parts per million of Abee by mass.  相似文献   

Recent Recession of Tropical Cliffy Coasts: Elevated benches and other coastal forms give evidence of eustatic changes in sea level     

Russell RJ 《Science (New York, N.Y.)》1963,139(3549):9-15

My fieldwork in various parts of the world leads me to the conclusion that the retreat of cliffy coasts through abrasion and solutional erosion during Recent times has produced a whole complex of forms, including conspicuous benches well above sea level where bedrock conditions are favorable. In addition, flats of other origin are being developed at various levels. Broad exposures of beach rock are a marine phenomenon only in that such exposure is a result of beach recession and of the uncovering of materials that had been cemented, under freshwater conditions, along water tables, in some places 6 or more feet above sea level (24, 25). Contemporary coral and algal flats are forming in some instances several feet above the level of the highest tides.  相似文献   

Identifying autism loci and genes by tracing recent shared ancestry   总被引：2，自引：0，他引：2  

Morrow EM  Yoo SY  Flavell SW  Kim TK  Lin Y  Hill RS  Mukaddes NM  Balkhy S  Gascon G  Hashmi A  Al-Saad S  Ware J  Joseph RM  Greenblatt R  Gleason D  Ertelt JA  Apse KA  Bodell A  Partlow JN  Barry B  Yao H  Markianos K  Ferland RJ  Greenberg ME  Walsh CA 《Science (New York, N.Y.)》2008,321(5886):218-223

To find inherited causes of autism-spectrum disorders, we studied families in which parents share ancestors, enhancing the role of inherited factors. We mapped several loci, some containing large, inherited, homozygous deletions that are likely mutations. The largest deletions implicated genes, including PCDH10 (protocadherin 10) and DIA1 (deleted in autism1, or c3orf58), whose level of expression changes in response to neuronal activity, a marker of genes involved in synaptic changes that underlie learning. A subset of genes, including NHE9 (Na+/H+ exchanger 9), showed additional potential mutations in patients with unrelated parents. Our findings highlight the utility of "homozygosity mapping" in heterogeneous disorders like autism but also suggest that defective regulation of gene expression after neural activity may be a mechanism common to seemingly diverse autism mutations.  相似文献   

PATENT REFORM PROSPECTS     

Russell B  Jewett HJ 《Science (New York, N.Y.)》1917,46(1200):629-631

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A new astrophysical setting for chondrule formation     

Krot AN  Meibom A  Russell SS  Alexander CM  Jeffries TE  Keil K 《Science (New York, N.Y.)》2001,291(5509):1776-1779

Chondrules in the metal-rich meteorites Hammadah al Hamra 237 and QUE 94411 have recorded highly energetic thermal events that resulted in complete vaporization of a dusty region of the solar nebula (dust/gas ratio of about 10 to 50 times solar). These chondrules formed under oxidizing conditions before condensation of iron-nickel metal, at temperatures greater than or equal to 1500 K, and were isolated from the cooling gas before condensation of moderately volatile elements such as manganese, sodium, potassium, and sulfur. This astrophysical environment is fundamentally different from conventional models for chondrule formation by localized, brief, repetitive heating events that resulted in incomplete melting of solid precursors initially residing at ambient temperatures below approximately 650 K.  相似文献   

Debating whale sanctuaries     

Papastavrou V  Leaper R 《Science (New York, N.Y.)》2005,309(5731):51-2; author reply 51-2

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Learned histamine release   总被引：4，自引：0，他引：4  

M Russell  K A Dark  R W Cummins  G Ellman  E Callaway  H V Peeke 《Science (New York, N.Y.)》1984,225(4663):733-734

Most of the effort directed at understanding the problems of allergy has focused on the interacting components of the immune system. The possibility that histamine may be released as a learned response has now been tested. In a classical conditioning procedure in which an immunologic challenge was paired with the presentation of an odor, guinea pigs showed a plasma histamine increase when presented with the odor alone. This suggests that the immune response can be enhanced through activity of the central nervous system.  相似文献   

Circadian rhythms: in the loop at last     

Van Gelder RN  Herzog ED  Schwartz WJ  Taghert PH 《Science (New York, N.Y.)》2003,300(5625):1534-1535

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THE UNITY OF ENGLISH WEIGHTS     

Russell S 《Science (New York, N.Y.)》1923,58(1509):442-443

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Capillary wrinkling of floating thin polymer films     

Huang J  Juszkiewicz M  de Jeu WH  Cerda E  Emrick T  Menon N  Russell TP 《Science (New York, N.Y.)》2007,317(5838):650-653

A freely floating polymer film, tens of nanometers in thickness, wrinkles under the capillary force exerted by a drop of water placed on its surface. The wrinkling pattern is characterized by the number and length of the wrinkles. The dependence of the number of wrinkles on the elastic properties of the film and on the capillary force exerted by the drop confirms recent theoretical predictions on the selection of a pattern with a well-defined length scale in the wrinkling instability. We combined scaling relations that were developed for the length of the wrinkles with those for the number of wrinkles to construct a metrology for measuring the elasticity and thickness of ultrathin films that relies on no more than a dish of fluid and a low-magnification microscope. We validated this method on polymer films modified by plasticizer. The relaxation of the wrinkles affords a simple method to study the viscoelastic response of ultrathin films.  相似文献