Support for Congolese conservationists     

Plumptre A  Hart T  Vedder A  Robinson J 《Science (New York, N.Y.)》2000,288(5466):617

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Recognition of a hidden mineral deposit by an artificial intelligence program     

Campbell AN  Hollister VF  Duda RO  Hart PE 《Science (New York, N.Y.)》1982,217(4563):927-929

A computer program that uses artificial intelligence techniques has successfully identified the location of a porphyry molybdenum deposit. Given geological maps of readily available predrilling exploration data for Mount Tolman in Washington State and using rules obtained from a porphyry molybdenum exploration specialist, the program (called PROSPECTOR) identified the location of previously unknown ore-grade mineralization. This appears to be the first reported determination of the location of mineralization by such a computer-based approach.  相似文献   

Ecology. Synthesizing U.S. river restoration efforts     

Bernhardt ES  Palmer MA  Allan JD  Alexander G  Barnas K  Brooks S  Carr J  Clayton S  Dahm C  Follstad-Shah J  Galat D  Gloss S  Goodwin P  Hart D  Hassett B  Jenkinson R  Katz S  Kondolf GM  Lake PS  Lave R  Meyer JL  O'donnell TK  Pagano L  Powell B  Sudduth E 《Science (New York, N.Y.)》2005,308(5722):636-637

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Response     

Hart SR  Hauri EH  Oschmann LA  Whitehead JA 《Science (New York, N.Y.)》1992,258(5083):821-822

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GROWTH STIMULATING PROPERTIES OF GRASS JUICE     

Kohler GO  Elvehjem CA  Hart EB 《Science (New York, N.Y.)》1936,83(2158):445-446

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Human chromosome 12 is required for elevated HIV-1 expression in human-hamster hybrid cells   总被引：24，自引：0，他引：24  

C E Hart  C Y Ou  J C Galphin  J Moore  L T Bacheler  J J Wasmuth  S R Petteway  G Schochetman 《Science (New York, N.Y.)》1989,246(4929):488-491

Host cell factors act together with regulatory genes of the human immunodeficiency virus (HIV) to control virus production. Human-Chinese hamster ovary hybrid cell clones were used to probe for human chromosomes involved in regulating HIV gene expression. DNA transfection experiments showed that 4 of 18 clones had high levels of HIV gene expression measured by both extracellular virus production and transactivation of the HIV long terminal repeat in the presence of the trans-activator (tat) gene. Karyotype analyses revealed a 94% concordance (17/18) between human chromosome 12 and HIV gene expression. Other chromosomes had an 11 to 72% concordance with virus production.  相似文献   

Deposits of amyloid beta protein in the central nervous system of transgenic mice.   总被引：10，自引：0，他引：10  

D O Wirak  R Bayney  T V Ramabhadran  R P Fracasso  J T Hart  P E Hauer  P Hsiau  S K Pekar  G A Scangos  B D Trapp 《Science (New York, N.Y.)》1991,253(5017):323-325

Alzheimer's disease is characterized by widespread deposition of amyloid in the central nervous system. The 4-kilodalton amyloid beta protein is derived from a larger amyloid precursor protein and forms amyloid deposits in the brain by an unknown pathological mechanism. Except for aged nonhuman primates, there is no animal model for Alzheimer's disease. Transgenic mice expressing amyloid beta protein in the brain could provide such a model. To investigate this possibility, the 4-kilodalton human amyloid beta protein was expressed under the control of the promoter of the human amyloid precursor protein in two lines of transgenic mice. Amyloid beta protein accumulated in the dendrites of some but not all hippocampal neurons in 1-year-old transgenic mice. Aggregates of the amyloid beta protein formed amyloid-like fibrils that are similar in appearance to those in the brains of patients with Alzheimer's disease.  相似文献   

Orphan strontium-87 in abyssal peridotites: daddy was a granite     

Snow JE  Hart SR  Dick HJ 《Science (New York, N.Y.)》1993,262(5141):1861-1863

The (87)Sr/(86)Sr ratios in some bulk abyssal and alpine peridotites are too high to be binary mixtures of depleted mantle and seawater components. The apparent excess, or "orphan," (87)Sr appears to be separated from its radioactive parent. Such observations were widely held to be analytical artifacts. Study of several occurrences of orphan (87)Sr shows that the orphan component in abyssal peridotite is located in the alteration products of olivine and enstatite in the peridotite. The orphan (87)Sr is most likely introduced by infiltration of low-temperature (<200 degrees C) seawater bearing suspended detrital particulates. These particulates include grains of detrital clay that are partly derived from continental (that is, granitic) sources and thus are highly radiogenic. Orphan (87)Sr and other radiogenic isotopes may provide a tracer for low-temperature seawater penetrating into the oceanic crust.  相似文献   

An analog of myristic acid with selective toxicity for African trypanosomes.   总被引：7，自引：0，他引：7  

T L Doering  J Raper  L U Buxbaum  S P Adams  J I Gordon  G W Hart  P T Englund 《Science (New York, N.Y.)》1991,252(5014):1851-1854

Trypanosoma brucei, the protozoan parasite responsible for African sleeping sickness, evades the host immune response through the process of antigenic variation. The variant antigen, known as the variant surface glycoprotein (VSG), is anchored to the cell surface by a glycosyl phosphatidylinositol (GPI) structure that contains myristate (n-tetradecanoate) as its only fatty acid component. The utilization of heteroatom-containing analogs of myristate was studied both in a cell-free system and in vivo. Results indicated that the specificity of fatty acid incorporation depends on chain length rather than on hydrophobicity. One analog, 10-(propoxy)decanoic acid, was highly toxic to trypanosomes in culture although it is nontoxic to mammalian cells.  相似文献   

Prevalence and shedding patterns of Campylobacter spp. in longitudinal studies of kennelled dogs     

Parsons BN  Williams NJ  Pinchbeck GL  Christley RM  Hart CA  Gaskell RM  Dawson S 《Veterinary journal (London, England : 1997)》2011,190(2):249-254

Dog ownership is considered a risk factor for campylobacteriosis in humans. This study investigated the prevalence and shedding of Campylobacter spp. in kennelled dogs. Faecal samples (n=399) were collected in longitudinal studies from 52 dogs in two kennels. Campylobacter spp. were isolated using charcoal-based selective agars and direct PCR. The prevalence of Campylobacter spp. in dogs in boarding kennels ranged from 46% (95% CI 22, 72) on entry, to 50% (95% CI 30, 70) overall, and in dogs in 'rescue' kennels from 68% (95% CI 49, 84) on entry to 73% (95%, CI 56, 87) overall. C. upsaliensis was isolated from 62% (95% CI 48, 73) of the dogs, whilst C. jejuni was isolated from 15% (95% CI 7, 26) of animals. The majority of infected dogs entered the kennels already carrying Campylobacter spp., and remained infected throughout their stay. However, in some cases, shedding appeared to commence after kennelling. Given that the prevalence of C. upsaliensis and C. jejuni was relatively high in dogs from both boarding and rescue kennels, such animals may pose a zoonotic risk.  相似文献