Treatment of lesions on the penis and prepuce of bulls     

RS. COPLAND  AA. BAKER  MD. RIVAL  PE. LENNON  PJ. CHENOWETH 《Australian veterinary journal》1989,66(11):378-380

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Simulation of the economic impact of transmissible gastroenteritis on commercial pig production in Australia   总被引：1，自引：0，他引：1  

BP MULLAN §  GT DAVIES†  RS CUTLER† 《Australian veterinary journal》1994,71(5):151-154

A simulation model (AUSPIG) was used to predict the effect of an increase in piglet deaths, and a reduction in growth rate and an increase in feed conversion ratio of grower pigs on the profitability of two herds representative of the Australian pig industry caused by the introduction of transmissible gastroenteritis virus (TGE) into those herds. For each herd, mortality rates for piglets under 1 week of age of 50% and 95% were assumed to represent a 'moderate' and a 'severe' outbreak, respectively. A reduction in net revenue of 70% was predicted to occur in the 6 months after a 'moderate' outbreak of TGE (100% for a 'severe' outbreak). This represents a total loss of between $260 and $330 per breeding sow in the 12 months after infection with the TGE virus. The likely financial impact of an outbreak of TGE on an Australian piggery is substantial and should be considered when addressing quarantine issues.  相似文献   

基于RS和GIS的柘皋河流域景观空间格局研究     

吉文帅  韩玉刚  管义国。 《勤云标准版测试》2007,(1)

在RS和GIS技术的支持下,运用景观生态学原理,以2000年LandsatTM7遥感数据为数据源,通过影像解译和实地调查获得柘皋河流域景观类型图,并采用景观指数分析法对流域内景观空间格局做定量分析,为流域内生态保护和区域经济的可持续发展提供有益参考。结果显示:柘皋河流域是以农业为主的发展模式。景观异质性高,分布相对均匀;耕地破碎化程度低,连通性好,利于农业发展;居民点与交通用地破碎化程度高,边缘效应强,对周围影响大。A区农业化和非农化矛盾最强烈。B区景观异质性高,景观类型分布均匀,生态结构稳定。C区景观异质性低,生态稳定性较差。  相似文献   

Spatial Response of Mammals to Late Quaternary Environmental Fluctuations     

RW Graham  EL Lundelius  MA Graham  EK Schroeder  RS Toomey  E Anderson  AD Barnosky  JA Burns  CS Churcher  DK Grayson  RD Guthrie  CR Harington  GT Jefferson  LD Martin  HG McDonald  RE Morlan  HA Semken  SD Webb  L Werdelin  MC Wilson 《Science (New York, N.Y.)》1996,272(5268):1601-1606

Analyses of fossil mammal faunas from 2945 localities in the United States demonstrate that the geographic ranges of individual species shifted at different times, in different directions, and at different rates in response to late Quaternary environmental fluctuations. The geographic pattern of faunal provinces was similar for the late Pleistocene and late Holocene, but differing environmental gradients resulted in dissimilar species composition for these biogeographic regions. Modern community patterns emerged only in the last few thousand years, and many late Pleistocene communities do not have modern analogs. Faunal heterogeneity was greater in the late Pleistocene.  相似文献   

Hillslope Evolution by Bedrock Landslides     

AL Densmore  RS Anderson  BG McAdoo  MA Ellis 《Science (New York, N.Y.)》1997,275(5298):369-372

Bedrock landsliding is a dominant geomorphic process in a number of high-relief landscapes, yet is neglected in landscape evolution models. A physical model of sliding in beans is presented, in which incremental lowering of one wall simulates baselevel fall and generates slides. Frequent small slides produce irregular hillslopes, on which steep toes and head scarps persist until being cleared by infrequent large slides. These steep segments are observed on hillslopes in high-relief landscapes and have been interpreted as evidence for increases in tectonic or climatic process rates. In certain cases, they may instead reflect normal hillslope evolution by landsliding.  相似文献