Mazama ash in the northeastern pacific     

Nelson CH  Kulm LD  Carlson PR  Duncan JR 《Science (New York, N.Y.)》1968,161(3836):47-49

Volcanic glass in marine sediments off Oregon and Washington correlates with continental deposits of Mount Mazama ash by stratigraphic position, refractive index, and radiocarbon dating. Ash deposited in the abyssal regions by turbidity currents is used for tracing of the dispersal routes of postglacial sediments and for evaluation of marine sedimentary processes.  相似文献   

Heterologous protein secretion from yeast   总被引：25，自引：0，他引：25  

R A Smith  M J Duncan  D T Moir 《Science (New York, N.Y.)》1985,229(4719):1219-1224

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Genome maps 1991 [wall chart   总被引：1，自引：0，他引：1  

M Chipperfield  M Maidek  P Pearson  M Ashburner  D M Glover  R D Saunders  I Duncan  D Hartl  J Merriam  G Lee 《Science (New York, N.Y.)》1991,254(5029):247-262

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Direct measurement of solar luminosity variation     

Willson RC  Duncan CH  Geist J 《Science (New York, N.Y.)》1980,207(4427):177-179

Two rocket flights of an absolute pyrheliometer, separated by 30 months, indicate an increase in solar luminosity (solar constant) of 0.4 percent. The significance of this result is considered in light of the instrument performance during the rocket flights and of pre- and postflight intercomparisons with independently maintained pyrheliometers. There is a high probability that the measured difference is real. Additional observations are required to determine whether the difference results from random fluctuations in solar luminosity, a nonrandom change of short duration, or a sustained change that has climatological significance.  相似文献   

Retraction     

Davis ST  Benson BG  Bramson HN  Chapman DE  Dickerson SH  Dold KM  Eberwein DJ  Edelstein M  Frye SV  Gampe RT  Grifffen RJ  Harris PA  Hassell AM  Holmes WD  Hunter RN  Knick VB  Lackey K  Lovejoy B  Luzzio MJ  Murray D  Parker P  Rocque WJ  Shewchuk-Chapman L  Veal JM  Walker DH  Kuyper LF 《Science (New York, N.Y.)》2002,298(5602):2327

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Hybrid speciation in experimental populations of yeast     

Greig D  Louis EJ  Borts RH  Travisano M 《Science (New York, N.Y.)》2002,298(5599):1773-1775

Most models of speciation require gradual change and geographic or ecological isolation for new species to arise. Homoploid hybrid speciation occurred readily between Saccharomyces cerevisiae and Saccharomyces paradoxus. Hybrids had high self-fertility (about 82%), low fertility when backcrossed to either parental species (about 7.5%), and vigorous growth under different thermal environments that favored one or the other of the parental species. Extensive karyotypic changes (tetrasomy) were observed in the hybrids, although genic incompatibilities accounted for 50% of the variation in self-fertility.  相似文献   

Elephant-induced structural changes in the vegetation and habitat selection by large herbivores in an African savanna     

Marion Valeix  Hervé Fritz  Rodolphe Sabatier  Felix Murindagomo  David Cumming  Patrick Duncan 《Biological conservation》2011,(2):902-912

African elephants can affect the quality of the habitat of other species by breaking or uprooting trees and shrubs in savannas. Their effect on vegetation has been widely studied but less is known about the effects of such vegetation changes on other animals. We studied how changes in the vegetation caused by elephants influence the selection of microhabitats by five African herbivore species (giraffe, kudu, steenbok, impala, and zebra) in Hwange National Park, Zimbabwe. There was no clear significant effect of overall elephant-induced vegetation changes on microhabitat selection except for the small species (steenbok and impala) that used vegetation modified by elephants preferentially. This is consistent with a medium-term browsing facilitation hypothesis. More subtle possible effects were detected for larger browsers (giraffe and kudu). They selected areas with broken and uprooted plants and avoided coppiced areas. All of the browsers selected sites characterized by plants uprooted and broken by elephants, which were associated with a higher visibility, and ultimately a better probability of detecting an approaching predator, suggesting that perceived predation risk plays an important role in microhabitat selection. These results illustrate how elephants can initiate indirect effects that influence microhabitat selection by other herbivores. Understanding the indirect effects of elephants through changes in food availability and predation risk thus needs further investigation. The results of this study do not provide support for the hypothesis that elephant-induced changes in the structure of habitats have caused the declines in the populations of the other herbivores in the study area.  相似文献   

α-Tocopherol-loaded Polycaprolactone (PCL) nanoparticles as a heat-activated oxygen scavenger     

Byun Y  Whiteside S  Cooksey K  Darby D  Dawson PL 《Journal of agricultural and food chemistry》2011,59(4):1428-1431

A nanoencapsulation technique was applied to an oxygen-scavenging system, and thermal processing was investigated as an activator to trigger the oxygen-scavenging reaction. α-Tocopherol-loaded polycaprolactone (PCL) nanoparticles (NPs) were prepared using an oil-in-water emulsion solvent evaporation method. The influences of iron(II) chloride, water, and thermal processing on the oxygen-scavenging capability were investigated. NPs without iron(II) chloride, moisture, and thermal processing had no oxygen-scavenging effect. However, the oxygen content (%) in the cup headspace of 20.9% decreased to 20.4% when the oxygen-scavenging system contained NPs, water, and iron(II) chloride. The oxygen content (%) decreased further to 19.5% when water was eliminated from the mixture. In this research, NPs and iron(II) chloride with thermal processing had an oxygen-scavenging capacity of 6.44 cm3 of O2/g and an oxygen-scavenging rate of 0.21 cm3 of O2 g(-1) day(-1). Results indicated that NPs and iron(II) chloride in an oxygen-scavenging system can be used as a heat-activated oxygen scavenger.  相似文献   

Arterioureteral fistula in a colt.     

F G Latimer  R Magnus  R B Duncan 《Equine veterinary journal》1991,23(6):483-484

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Could the worms have turned?     

S Love  J L Duncan 《Equine veterinary journal》1991,23(3):152-154

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