Characterizing the complexity of landscape boundaries by remote sensing   总被引：9，自引：0，他引：9  

Jean Paul Metzger  Etienne Muller 《Landscape Ecology》1996,11(2):65-77

This paper presents a method for characterizing the complexity of landscape boundaries by remote sensing. This characterization is supported by a new boundary typology, that takes into account points where three or more landcovers converge (i.e., convergency points or coverts). Landscape boundary richness and diversity indices were proposed and calculated over 19 landscapes in South-East Brazil. Results showed that landscape boundaries, especially convergency points, provided an enrichment in landscape pattern analysis. Landcover boundary diversities were significantly related to landcover shape: elongated riparian units had the highest values for boundary diversity and coverts proportion indices. On the other hand, landscape analysis showed that indices of shape, richness, diversity and coverts proportion provided an additional evaluation of landcover spatial distribution within the landscape.  相似文献   

Early migration of immature Fasciola hepatica and associated liver pathology in cattle   总被引：1，自引：0，他引：1  

T G Doy  D L Hughes 《Research in veterinary science》1984,37(2):219-222

Immature Fasciola hepatica were successfully recovered from the body cavity of cattle from two to 21 days after oral infection. Flukes had penetrated the liver in large numbers by day 7 but there did not appear to be a corresponding reduction in the numbers recovered from the body cavity. Liver pathology showed a typical progressive tissue disruption with a neutrophil and lymphocyte infiltration by day 7 and a marked eosinophil response from day 14. The mesothelium of the liver capsule underwent metaplasia, becoming ultimately highly active and columnar.  相似文献   

The low incidence of leptospirosis in British deer     

G I Twigg  D M Hughes  A McDiarmid 《The Veterinary record》1973,93(4):98-100

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Sodium deprivation, feather pecking and activity in laying hens     

B O Hughes  C C Whitehead 《British poultry science》1974,15(5):435-439

When a diet containing only 0.038% sodium was fed to two strains of laying hens for four weeks they showed no increase in feather pecking, toe pecking, pecking activity or general activity, although egg production almost completely ceased. This finding is unexpected in view of recent reports to the contrary under field conditions. It is postulated that very low sodium intakes may be less deleterious than intermediate intakes which permit some laying, and therefore sodium loss, to continue. The absence of adverse behavioural effects emphasises the potential value of sodium deprivation as a means of halting egg production.  相似文献   

Experimental production of infectious bovine keratoconjunctivitis: comparison of serological and immunological responses using pili fractions of Moraxella bovis.          下载免费PDF全文

G W Pugh  Jr  D E Hughes 《Canadian journal of veterinary research》1976,40(1):60-66

The effect of vaccinating cattle and mice on the development of keratoconjunctivitis was studied. Cattle were vaccinated with whole cells, disrupted cells and pili fractions of three strains of Moraxella bovis. Mice were vaccinated with pili fractions of three strains. The resistance of all vaccinated animals was challenged with virulent cultures of M. bovis. In an attempt to correlate the response seen after vaccination and challenge with a pili fraction of M. bovis, vaccinated cattle and mice were grouped on the basis of signs of disease manifested and compared on the basis of serological responses. Serum samples were tested for antibodies by a gel diffusion precipitin test. A greater number of the sera of resistant cattle had antibodies to the homologous pili antigen than those of vaccinated nonresistant cattle. Cattle vaccinated with disrupted cells were not resistant to infectious bovine kerato-conjuctivitis and their sera lacked antibodies against the pili antigens. Vaccinated mice were more resistant to infectious bovine kerato-conjuctivitis and their sera lacked antibodies against the pili antigens. Vaccinated mice were more resistant to challenge exposure by homologous than heterologous cultures. A greater number of the sera of resistant mice had antibodies to pili antigens than nonresistant mice.  相似文献   

Zur Frage der Ausbreitung von Luftkeimen aus Tierställen     

Wolfgang Müller  Paul Wieser  Heinrich Kühme 《Zoonoses and public health》1978,25(3):216-224

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A five-year study of infectious bovine keratoconjunctivitis in a beef herd   总被引：12，自引：0，他引：12  

D E Hughes  G W Pugh 《Journal of the American Veterinary Medical Association》1970,157(4):443-451

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Cellular and humoral local immune responses in sheep experimentally infected with Oestrus ovis (Diptera: Oestridae)     

Tabouret G  Lacroux C  Andreoletti O  Bergeaud JP  Hailu-Tolosa Y  Hoste H  Prevot F  Grisez C  Dorchies P  Jacquiet P 《Veterinary research》2003,34(2):231-241

Cellular and humoral local responses were investigated following repetitive artificial Oestrus ovis infections in lambs. The presence of larvae induced a huge local recruitment of either leucocytes (T and B lymphocytes, macrophages) or granulocytes (eosinophils, mast cells and globule leucocytes). This cellular response was more pronounced in the ethmoid and sinus (development sites of second and third instar larvae) than in the septum or turbinates where first instar larvae migrate. Infected lambs produced Oestrus ovis specific IgG and IgA antibodies in their mucus. This local humoral response was mainly directed against larval salivary gland antigens and not against larval digestive tract antigens. Compared to the control animals, the sinusal mucosa of infected animals was extremely thickened and the epithelium exhibited hyperplasia, metaplasia and eosinophilic exocytosis. The possible roles of these local immune responses in the regulation of O. ovis larvae populations in sheep are discussed.  相似文献   

Detection, quantification, and pharmacokinetics of furosemide and its effects on urinary specific gravity following IV administration to horses     

Dirikolu L  Lehner AF  Hughes C  Karpiesiuk W  Camargo FC  Harkins JD  Woods WE  Bosken JM  Boyles J  Troppmann A  Fisher M  Tobin T 《Veterinary therapeutics : research in applied veterinary medicine》2003,4(4):350-363

Furosemide is a potent loop diuretic used for the prevention of exercise-induced pulmonary hemorrhage in horses. This drug may interfere with the detection of other substances by reducing urinary concentrations, so its use is strictly regulated. The regulation of furosemide in many racing jurisdictions is based on paired limits of urinary SG (<1.010) and serum furosemide concentrations (>100 ng/ml). To validate this regulatory mechanism, a liquid chromatography/mass spectrometry/mass spectrometry method employing a solid-phase extraction procedure and furosemide-d5 as an internal standard was developed. The method was used to determine the pharmacokinetic parameters of furosemide in equine serum samples and its effects on urinary SG after IV administration (250 mg) to 10 horses. Pharmacokinetic analysis showed that serum concentrations of furosemide were well described by a two-compartmental open model. Based on results in this study, it is very unlikely for horses to have serum furosemide concentrations greater than 100 ng/ml or urine SG less than 1.010 at 4 hours after administration (250 mg IV). However, it should be remembered that urine SG is a highly variable measurement in horses, and even without furosemide administration, some horses might naturally have urine SG values less than 1.010.  相似文献   

Field efficacy of ivermectin plus praziquantel oral paste against naturally acquired gastrointestinal nematodes and cestodes of horses in North America and Europe     

Rehbein S  Holste JE  Doucet MY  Fenger C  Paul AJ  Reinemeyer CR  Smith LL  Yoon S  Marley SE 《Veterinary therapeutics : research in applied veterinary medicine》2003,4(3):220-227

The efficacy of an oral formulation of ivermectin plus praziquantel in the reduction of nematode and cestode egg counts in horses was assessed in 273 horses under field conditions at 15 sites in North America (n = 6) and Europe (n = 9). Horses were confirmed by fecal examination to have natural infections of strongyles (100%) and tapeworms (76%). Replicates of four horses were formed at each site, and in each replicate three animals received ivermectin (0.2 mg/kg body weight) plus praziquantel (1 mg/kg body weight) oral paste and one animal remained untreated or received vehicle paste. Fecal samples were collected for fecal nematode and cestode egg counting before and 7, 8, 9, 14, 15, and 16 days after treatment. Horses treated with ivermectin plus praziquantel oral paste had significantly (P <.01) lower posttreatment strongylid and cestode egg counts (reductions of 98% or more) than controls. Combined site analyses revealed that 95% or 96% of the horses positive for cestode eggs before treatment that were treated with ivermectin plus praziquantel were negative for cestode eggs at each posttreatment fecal examination. No adverse reactions attributable to ivermectin plus praziquantel oral paste treatments were observed. The results of the studies demonstrated that ivermectin plus praziquantel paste was highly effective in reducing egg shedding by gastrointestinal nematodes and cestodes, and no adverse reactions were observed in horses treated under field conditions.  相似文献