Lead and Helium Isotope Evidence from Oceanic Basalts for a Common Deep Source of Mantle Plumes     

BB Hanan  DW Graham 《Science (New York, N.Y.)》1996,272(5264):991-995

Linear arrays in lead isotope space for mid-ocean ridge basalts (MORBs) converge on a single end-member component that has intermediate lead, strontium, and neodymium isotope ratios compared with the total database for oceanic island basalts (OIBs) and MORBs. The MORB data are consistent with the presence of a common mantle source region for OIBs that is sampled by mantle plumes. 3He/4He ratios for MORBs show both positive and negative correlation with the 206Pb/204Pb ratios, depending on the MORB suite. These data suggest that the common mantle source is located in the transition zone region. This region contains recycled, oceanic crustal protoliths that incorporated some continental lead before their subduction during the past 300 to 2000 million years.  相似文献   

The use of reflective mulch to reduce the incidence of watermelon mosaic virus in Western Australia     

G.D. McLean  J.R. Burt  D.W. Thomas  A.N. Sproul 《Crop Protection》1982,1(4):491-496

Watermelon mosaic virus has caused losses in cucurbits in the last 8 years in the Gascoyne River district of Western Australia. Neither insecticides nor oil sprays have reduced the incidence of this disease. In three trials, plants mulched with reflective (aluminium) polythene were less infected (by 21%, 30% and 72%) than were those given a control treatment; yield increases of watermelons ranged from 77% to 270%. Black polythene mulch also reduced the incidence of virus and increased yield, but to a lesser degree. In all experiments the disease incidence rose more slowly in the mulch plots: this effect contributed greatly to the observed increase in yield.  相似文献   

THE TEXAS ACADEMY OF SCIENCE     

Burt FA 《Science (New York, N.Y.)》1940,92(2400):607-608

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THE CANINE LATERAL THORACIC RADIOGRAPH     

CrispinP.  Spencer  DVM  Norman  Ackerman  DVM JamesK.  Burt  DVM 《Veterinary radiology & ultrasound》1981,22(6):262-266

Selected structures seen on right and left lateral thoracic radiographs of 12 dogs were evaluated for differences in position, size, and shape. The size and position of the cardiac silhouette were different when thoracic radiographs made in left and right lateral recumbency were compared. These changes were, however, considered insignificant. The position of the right cranial lobe bronchus relative to the left varied in right lateral recumbency and left lateral recumbency. The right cranial lung lobe was better aerated when dogs were positioned in left lateral recumbency.
Lesions seen in the caudal portion of the left cranial lung lobe or the right middle lobe were masked when the affected lobe was dependent, and enhanced when the affected lung lobe was non-dependent. It is believed that this difference occurred due to compression of the dependent lung with greater aeration of the non-dependent lung.  相似文献   

Congenital Neuromuscular Esophageal Disease in a Litter of Newfoundland Puppies1     

Anthony Schwartz  Carl E. Ravin  Richard H. Greenspan  RalphS. Schoemann  JamesK. Burt 《Veterinary radiology & ultrasound》1976,17(3):101-105

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Temporal and spatial patterns of nitrate losses from an agricultural catchment     

T.P. Burt  B.P. Arkell 《Soil Use and Management》1987,3(4):138-142

Abstract. Nitrate losses from a small catchment of mixed land use in south Devon, England, are described. The temporal pattern of leaching is dominated by major losses through the winter months when both streamflow and nitrate concentration are large. Storm runoff is generated mainly by subsurface stormflow, and nitrate losses are particularly important at such times. The spatial pattern of nitrate loss from the catchment is controlled both by land use and by topography.  相似文献   

Maturation of insulin and glucose responses to normal feeding in foals     

GB SMYTH †  DW YOUNG‡  SH DURAN 《Australian veterinary journal》1993,70(4):129-132

SUMMARY Postprandial insulin and glucose concentrations were measured in 3 Arabian and 3 Thoroughbred foals at 1 day, 1 week, 1 month and 3 months of age. Prefeeding serum Insulin concentrations were similar in foals at 1 day (25.9 ± 5.1 pmol/L), 1 week (32.4 ± 5.8 pmol/L), and 1 month (38.2 + 7.9 pmol/L), but had Increased significantly to 131.0 ± 20.2 pmol/L at 3 months of age (P < 0.05). There was significantly increased serum Insulin secretion after a feed In foals at 3 months of age (P < 0.05) when compared with that at younger ages. Prefeeding serum glucose concentrations ranged from 6.0 ± 0.7 mmol/L at 1 day, to 5.9 ± 0.9 mmol/L at 1 week, 4.9 ± 1.7 mmol/L at 1 month, and 4.4 ± 1.5 mmol/L at 3 months of age. There were lower postprandial glucose concentrations with advancing age. It appeared that there was a period of maturation in pancreatic β-cell function after birth in foals, which reached adult levels by 3 months of age.  相似文献   

The pyrethrins and related compounds. XIX Geometrical and optical isomers of 2,2-dimethyl-3-(2,2-dichlorovinyl)-cyclopropanecarboxylic acid and insecticidal esters with 5-benzyi-3-furylmethyi and 3-phenoxybenzyl alcohols     

Paul E. Burt  Michael Elliott  Andrew W. Earnham  Norman F. Janes  Paul H. Needham  David A. Pulman 《Pest management science》1974,5(6):791-799

Esters of 2,2-dimethyl-3-(2,2-dichlorovinyl)-cyclopropanecarboxylic acid with appropriate alcohols are more active insecticides than the corresponding 3-isobutenyl compounds (chrysanthemates). (±)-Cis and (±)-trans forms of the dichloro acid are obtained by fractional crystallisation of the mixed acids or by hydrolysis of the ethyl esters separated by fractional distillation. The (±)-cis and (±)-trans acids are resolved into their (+)- and (-)-forms with α-methyl-benzylamine and threo-l-p-nitrophenyl-2-N,N-dimethyiamino-propane-1,3-diol respectively. As for the corresponding chrysanthemates, the (+)-cis and (+)-trans acids give esters more active as insecticides than their enantiomers.  相似文献   

Tidal Overmixing in Estuaries     

Burt WV  Queen J 《Science (New York, N.Y.)》1957,126(3280):973-974

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鸭基因组研究现状和未来展望   总被引：5，自引：1，他引：4  

黄银花  李宁  D.W.Burt  吴非 《中国家禽》2009,31(9)

作为禽流感病毒、乙肝病毒的自然贮存库和重要的农业经济动物,鸭在分子生物学(如宿主与病原物互作机制)和分子遗传学(如生长和屠体性状主效基因的克隆)领域的重要地位逐渐为人们所认可.近年来,鸭的基因组学研究取得了一些进展:①构建了鸭的遗传和细胞遗传图谱,并在此基础上定位了鸭生长、屠体和肉质性状的QTLs;②开展了鸡和鸭的比较基因定位研究;③建立了鸭的全基因组BAC文库;④克隆了约3 000条鸭的ESTs序列;⑤利用微卫星标记估计了鸭的遗传多样性.但与其它模式生物(如鸡、猪)相比较,鸭的基因组学研究仍处于起始阶段.随着分子生物学技术,特别是全基因组序列测定技术的发展,高密度的鸭遗传图谱、高分辨率的鸭和鸡以及其它脊椎动物的比较遗传图谱将会被构建,甚至是鸭全基因组序列的测定.这些基因组信息的获得将为大规模的鸭品种资源评定、重要经济性状分子机理的剖析进而改良其生产性能(如提高产蛋量和内质性能、增加对禽流感等疾病的抗性)奠定基础.  相似文献