Silicon in carbonaceous chondrite metal: relic of high-temperature condensation     

Grossman L  Olsen E  Lattimer JM 《Science (New York, N.Y.)》1979,206(4417):449-451

Electron microprobe analyses of an extraordinarily large metal grain from the Murchison type 2 carbonaceous chondrite gave 0.24 mole percent silicon. Thermodynamic calculations show that this is a natural consequence of condensation of alloys from the solar nebular gas at a total pressure l0(-5) less, similar P(tot) < l0(-3) atmosphere, provided they failed to equilibrate with it after cooling to < 1200 kelvins.  相似文献   

栽培稻分类方法的比较   总被引：18，自引：3，他引：18  

周汇  JC Glaszmann  程侃声  施晓群 《中国水稻科学》1988,2(1):1-7

 为了比较Glaszmann和程侃声等对亚洲栽培稻的分类体系,将Glaszmann氏提供的197个水稻品种的同功酶位点原始记录和程氏对它们就6个形态性状的评分作了主成分分析和聚类分析。结果显示二人的分类基本一致,数值分类也表明栽培稻可以只分籼粳两个亚种,处于中间的少数品种可称为偏籼或偏粳。程氏采用的“性状指数法”似更为便利而有效,特别适于田间及育种工作,虽然带有一定的经验成分,但加以生化或数值分类的检验,即可弥补该法的不足,有助于澄清个别不够明确和错划的事例。因此,我们建议为求得最佳的分类系统,最好运用二种以上的方法,相互补充校正。  相似文献   

Comparison of abomasal emptying in neonatal calves with a nuclear scintigraphic procedure.     

G Nappert  J C Lattimer 《Canadian journal of veterinary research》2001,65(1):50-54

The purpose of the present study was to demonstrate that nuclear medicine technology allows observation of the effect that milk clotting has on abomasal emptying in the living neonatal calf. Scintigraphic evaluation of abomasal emptying was carried out in 6 healthy male Holstein calves. The calves were fed 10% of their body weight daily as whole cow's milk that was divided equally and consumed as 2 feedings via a nipple bottle. One day before the nuclear scintigraphic procedure, the calves were randomly fed whole cow's milk, or an oral rehydration solution (ORS) containing bicarbonate and high levels of soluble fibre was fed for 3 consecutive feedings an hour before the portion of milk. For each calf, both feeding programs were repeated twice at a one-week interval. Immediately following administration of the 99mTC-sulfur-colloid-containing milk, the calves were imaged with the gamma camera positioned lateral and ventral to the abomasum. Additional right lateral and ventral views of the abomasum were collected at 15, 30, 45, 60, 90, 120, 150, 180, 210, and 240 min after administration of the radionuclide. Blood glucose determination were performed at one-hour intervals for 7 h after feeding milk to evaluate milk digestibility in both feeding programs. No significant differences in the results of the glucose absorption test or in the radionuclide counts of the abomasum were found between both feeding programs. Scintigraphic evaluation of abomasal emptying was found to be a useful technique for visualization of milk clotting and to test the effect of an ORS on milk digestibility.  相似文献   

Age-related differences in collagen crimp patterns in the superficial digital flexor tendon core region of untrained horses   总被引：5，自引：0，他引：5  

JC PATTERSON-KANE  EC FIRTH  AE GOODSHIP  DAD PARRY 《Australian veterinary journal》1997,75(1):39-44

Objective To measure collagen fibril crimp angles and lengths as well as collagen fibril mass-average diameters in central and peripheral regions of the superficial digital flexor tendon of wild horses, to ascertain any age-related changes in either region in the absence of imposed galloping exercise.
Design Measurements from a random cull of wild horses.
Sample population Superficial digital flexor tendon samples were taken from 23 wild horses ranging in age from two to ten years.
Procedure Horses were divided into 'young' (< 5 years, n = 10), 'middle-aged' (5 to < 10 years, n = 9) and 'old' groups (10+ years, n = 4) and the mean crimp angle, mean crimp length and collagen fibril mass-average diameter calculated for the central region, and for the peripheral region of each group. Differences between groups and regions were analysed using two-tailed t tests.
Results The crimp angle for the central region was found to decrease with age, so that in old horses it was smaller than that for the tendon periphery (P < 0.05). The crimp angle for the latter region did not alter significantly with age. Crimp period lengths and collagen fibril mass-average diameters did not show significant changes with age in either region.
Conclusion Reduction of the crimp angle in the core of the superficial digital flexor tendon occurs normally with age, as tendons of older animals would have undergone a higher number of loading cycles. It is possible that athletic training increases the frequency and/or the magnitude of high loading cycles experienced by the tendon, and may accelerate and worsen the normal load-related ageing process in the superficial digital flexor tendons of young performance horses, particularly in the central regions where lesions usually occur.  相似文献   

Fasciola hepatica infection in farmed emus (Dromaius novaehollandiae)     

JL VAUGHAN  JA CHARLES  JC BORAY 《Australian veterinary journal》1997,75(11):811-813

Objective To describe two cases of infection with Fasciola hepatica i n young farmed emus, subacute and chronic fasci-olosis and a response to treatment of the flock with albenda-zole.
Procedure Gross lesions were found at necropsy and hepatic lesions in microscopic examination. The parasite recovered from one emu was identified by its morphological characteristics and an egg count reduction test was carried out after treatment of the flock with albendazole.
Results Hepatic lesions resembling subacute and chronic fasciolosis of ruminants were identified. An adult fluke was recovered from the liver of one of the birds and was identified as F hepatica . The eggs of the fluke were irregular in shape and size. No fluke eggs were identifiable in faeces of live emus 10 days after treatment of the flock with albendazole at a dose of 10 mg/kg.
Conclusions This is the first reported case of infection with F hepatica i n farmed emus and the first report of the occurrence of Fasciola infection is the class Aves. The irregular shape and size of the eggs may be attributable to infection of an aberrant host. Treatment with albendazole eliminated eggs from the faeces of the flock.  相似文献   

Verotoxin-producing Escherichia coli from the faeces of sheep, calves and pigs   总被引：4，自引：0，他引：4  

H. SIDJABAT-TAMBUNAN  JC BENSINK 《Australian veterinary journal》1997,75(4):292-293

  相似文献   

Closantel resistance in Huemonchus contortus from sheep     

PF ROLFE  JC BORAY  C. FITZGIBBON  G. PARSONS  P. KEMSLEY  N. SANGSTER 《Australian veterinary journal》1990,67(1):29-31

  相似文献   

Phenylbutazone in racing Greyhounds: plasma and urinary residues 24 and 48 hours after a single intravenous administration     

PC MILLS  JC NG†  KV SKELTON†  AA SEAWRIGHT  DE AUER† 《Australian veterinary journal》1995,72(8):304-308

SUMMARY The concentrations of phenylbutazone (PBZ), oxyphenbutazone (OPBZ) and gammahydroxyphenylbutazone (OHPBZ) in plasma and urine from 50 Greyhounds 24 and 48 h after the intravenous administration of a single dose of PBZ (30 mg/kg) were measured. The 24 h plasma concentrations of OPBZ and OHPBZ, the 48 h plasma concentration of OHPBZ and the 24 h urinary concentration of PBZ were normally distributed, while log transformations were required before the 24 h plasma concentration of PBZ and the 24 and 48 h urinary concentrations of OPBZ and OHPBZ became normally distributed. The 95%, 99%, 99.9% and 99.99% upper predicted confidence intervals for both 24 h and 48 h plasma and urinary concentrations demonstrated wide potential variation in the concentration of the analytes should PBZ be administered to Greyhounds. The 24 h plasma and urinary concentrations of PBZ were weakly correlated, but no similar relationship existed for OPBZ or OHPBZ. The urinary concentrations of each analyte were not affected by the trainer or sex of the Greyhound or the urinary pH. We conclude that it would be impossible to predict the timing of the PBZ administration or the plasma concentration of PBZ from the measurement of the concentration of PBZ in a single sample of urine.  相似文献   

Organic carbon fluxes and ecological recovery from the cretaceous-tertiary mass extinction     

S D'Hondt  P Donaghay  JC Zachos  D Luttenberg  M Lindinger 《Science (New York, N.Y.)》1998,282(5387):276-279

Differences between the carbon isotopic values of carbonates secreted by planktic and benthic organisms did not recover to stable preextinction levels for more than 3 million years after the Cretaceous-Tertiary mass extinction. These decreased differences may have resulted from a smaller proportion of marine biological production sinking to deep water in the postextinction ocean. Under this hypothesis, marine production may have recovered shortly after the mass extinction, but the structure of the open-ocean ecosystem did not fully recover for more than 3 million years.  相似文献   

Photonic band gap guidance in optical fibers   总被引：3，自引：0，他引：3  

JC Knight  J Broeng  TA Birks  PSJ Russell 《Science (New York, N.Y.)》1998,282(5393):1476-1478

A fundamentally different type of optical waveguide structure is demonstrated, in which light is confined to the vicinity of a low-index region by a two-dimensional photonic band gap crystal. The waveguide consists of an extra air hole in an otherwise regular honeycomb pattern of holes running down the length of a fine silica glass fiber. Optical fibers based on this waveguide mechanism support guided modes with extraordinary properties.  相似文献