Radar detection of the nucleus and coma of comet hyakutake     

JK Harmon  SJ Ostro  LAM Benner  KD Rosema  RF Jurgens  R Winkler  DK Yeomans  D Choate  R Cormier  JD Giorgini  DL Mitchell  PW Chodas  R Rose  D Kelley  MA Slade  ML Thomas 《Science (New York, N.Y.)》1997,278(5345):1921-1924

Radar observations of comet Hyakutake (C/1996 B2) made at the Goldstone Deep Space Communications Complex in California have detected echoes from the nucleus and from large grains in the inner coma. The nucleus of this bright comet was estimated to be only 2 to 3 kilometers in diameter. Models of the coma echo indicate backscatter from porous, centimeter-size grains ejected anisotropically at velocities of tens of meters per second. The radar observations suggest that a comet's activity may be a poor indicator of its size and provide evidence that large grains constitute an important component of the mass loss from a typical active comet.  相似文献   

管道涂敷施工前表面处理研究     

Sidney A Taylor  BS ChE  MBA JD 《油气储运》2005,24(Z1)

通常情况下,管道涂敷商在涂敷新涂层之前,都要将管道表面处理到Sa 2.5级或者近白级,但是在施工现场却很难达到这一标准.讨论了旧涂层去除的常规方法、表面处理以及可预见的结果,并讨论了当前在表面处理方面的研究成果以及在涂层涂敷过程中二次生锈的各种影响.  相似文献   

Fossil Evidence for a Late Cretaceous Origin of "Hoofed" Mammals     

JD Archibald 《Science (New York, N.Y.)》1996,272(5265):1150-1153

Seventeen of eighteen orders of living placental mammals are not known before 65 million years ago. The monophyly of each order is well established, but interrelations have been less certain. A superordinal grouping of up to seven extant orders plus a variety of extinct orders, all included within Ungulata ("hoofed" mammals), can be linked to Late Cretaceous mammals from the 85-million-year-old Bissekty Formation, Uzbekistan (and, less certainly, North America and Europe), thus pushing the origin of this major clade back by 20 million years. Ungulatomorphs are not closely related to primates, rodents, or rabbits.  相似文献   

Sagittal plane slab fractures of the third carpal bone in 45 racing Thoroughbred horses     

Rose Tallon  Henry O’Neill  Bruce Bladon 《Equine veterinary journal》2020,52(5):692-698

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A moving light stimulus elicits a sustained swimming response in farmed Atlantic salmon, <Emphasis Type="Italic">Salmo salar</Emphasis> L.     

Herbert NA  Kadri S  Huntingford FA 《Fish physiology and biochemistry》2011,37(2):317-325

The productivity and welfare benefits of sustained swimming in fish are well documented, but are not yet exploited in commercial aquaculture. We report here on a study designed to test the feasibility of inducing sustained exercise in Atlantic salmon (Salmo salar L.) using a novel lighting device that provides an apparently moving light pattern. It was found that such a device could induce sustained swimming in Atlantic salmon held in tanks and that a centrally placed (inner ring) light system was far more effective in this context than one in which lights were placed on the outer wall of tanks. The central configuration was associated with enhanced rates of growth, feed conversion and reduced levels of plasma cortisol. Such developments in fish swimming technologies may assist the sustainability of finfish aquaculture through promotion of sustained exercise leading to improved productivity and welfare.  相似文献   

Use of binary and truncated negative binomial modelling in the analysis of recreational catch data     

Michael F. O&#x;Neill  Malcolm J. Faddy 《Fisheries Research》2003,60(2-3):471-477

Data from surveys of recreational anglers fishing on three estuaries in eastern Australia reveal highly skewed distributions of catches with many zeros. Such data may be analyzed using a two-component approach involving a binary (zero/non-zero catch) response and the conditionally distributed non-zero catches. A truncated negative binomial model was effective in analyzing the non-zero catches. Covariates were incorporated in the modelling, and their critical assessment has led to improved measures of fishing effort for this recreational fishery.  相似文献   

Treatment of Animal Toxicoses: A Regulatory Perspective     

Susan J. Bright DVM  Michael J. Murphy DVM  JD  PhD  Janice C. Steinschneider MA  JD  Randall A. Lovell DVM  PhD  Lynn O. Post DVM  PhD  CAPT  USPHS 《Veterinary Clinics of North America: Food Animal Practice》2011,27(2):481-512

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Pulmonary lesions and Mycobacterium bovis excretion from the respiratory tract of tuberculin reacting cattle   总被引：1，自引：0，他引：1  

S G McIlroy  S D Neill  R M McCracken 《The Veterinary record》1986,118(26):718-721

Although it is generally recognised that tuberculous lesions are present in lymph nodes associated with the respiratory tract in approximately 90 per cent of reactors with confirmed infection, lung lesions are found in only 1 to 2 per cent of such cases during abattoir examination. When lung lesions are not detected, it has been claimed that such cattle are non-excretors and thus unimportant in the epidemiology of the disease. In this study the lungs of 55 reactor cattle were sliced into sections approximately 0.5 cm thick. Tuberculous lesions were evident in over 70 per cent of lungs from reactors with concurrent lesions in lymph nodes of the respiratory system. Further, M bovis was isolated from single samples of nasal and, or, tracheal mucus taken at slaughter in 19 per cent of confirmed cases. Several of these reactors had a clear tuberculin test less than six months previously indicating recent infection. This study confirms the continued importance of the infected bovine in the epidemiology and current eradication of bovine tuberculosis. It is suggested that all tuberculous cattle with lesions in respiratory lymph nodes, rather than being regarded as non-excretors, should be considered as possible excretors and thus important sources of infection for other cattle both within and between herds.  相似文献   

Equine neural angiostrongylosis     

JD WRIGHT  WR KELLY†  J. HAMILTON  AH WADELL† 《Australian veterinary journal》1991,68(2):58-60

Verminous encephalomyelitis due to Angiostrongylus cantonensis larvae was diagnosed in 2 foals at necropsy. The principal clinical feature was tetraparesis, although history and neurological examination revealed progressive and multifocal neurological disease. At presentation, a tentative diagnosis of parasitic larval migration involving the central nervous system (CNS), presumably due to Strongylus vulgaris, was proposed. Dissection of the spinal cord in one case resulted in recovery of intact larvae of both sexes of A. cantonensis. In both foals, histopathology of the brain and spinal cord revealed nematode sections which were consistent with A. cantonensis larvae.  相似文献   

Fish Pathology     

JD Humphrey 《Australian veterinary journal》2002,80(6):370-370

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