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Rangelands comprise a large component of the terrestrial land surface and provide critical ecosystem services, but they are degrading rapidly. Long-term rangeland monitoring with detailed, nonsubjective, quantitative observations can be expensive and difficult to maintain over time. Unmanned aerial vehicles (UAVs) provide an alternative means to gather unbiased and consistent datasets with similar details to field-based monitoring data. Comparing summer 2017 UAV images with long-term plot measurements, we demonstrate that rangeland vegetation cover changes can be accurately quantified and estimate an increase in total absolute shrub/subshrub cover from 34% in 1935 to > 80% in 2017 in central Arizona. We recommend UAV image-based rangeland monitoring for land managers interested in a few specific and dominant species, such as the foundation species, indicator species, or invasive species that require targeted monitoring. Land managers can identify and continuously monitor trends in rangeland condition, health, and degradation related to specific land use policies and management strategies.  相似文献   
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AIMS: To determine current practices and attitudes towards vaccination of dogs and cats of veterinarians in New Zealand; the methods used for informing clients on which vaccines to use, and the preferred site for vaccination of cats.

METHODS: A postal questionnaire was sent to all 483 listed veterinary practices in New Zealand during February 2012. Some questions were specific to pet dogs, cats, or working farm dogs. Responses were categorised according to practice type and geographical region of the respondent. Factors associated with respondent recommendation of annual vaccination with modified live viral (MLV) vaccines were examined using logistic regression analysis. Vaccines that were considered to be essential for every animal were defined as core; those that may be recommended for animals whose location or lifestyle placed them at risk, were defined as non-core.

RESULTS: There were 204 useable returns, equivalent to a response rate of 42.2%, distributed across the country. Annual vaccination with MLV vaccines of dogs was recommended by 54/198 (27.3%) respondents, and of cats by 107/181 (59.1%) respondents. Factors associated with the recommendation of annual administration of MLV vaccines to dogs included being a companion animal practice, a desire for policies on vaccination to be left to individual clinics, and having one veterinarian in the practice. Administration of the final vaccination for puppies was recommended at ≥14 weeks old by 55/185 (29.7%) respondents, and for kittens at ≥13 weeks old by 42/183 (23%) respondents. Of respondents that administered MLV vaccines annually, 62/103 (60.2%) believed reducing the frequency of vaccination would reduce income, and 52/103 (50.5%) considered it would have a negative effect on animal health. Advice to enable clients to decide which non-core vaccines were administered was given by 181/199 (91%) respondents. Factors considered when recommending a vaccine included consideration of risk to individual patients (190/203; 93.6%), requirements of boarding kennels/catteries (165/203; 81.3%) and clinic vaccination policy (142/203; 70%). The preferred site for administering MLV vaccines to cats was the dorsal neck or inter-scapular region (137/198; 69.2%). Amongst respondents, 18 wanted disease surveillance information to allow for truly informed decisions to be made about vaccination.

CONCLUSIONS AND CLINICAL RELEVANCE: Veterinarians can now compare their own vaccination practices and attitudes with those of veterinarians nationally, and internationally. There is a need for national surveillance information and for continued education of the public and commercial kennel and cattery owners for optimal vaccination strategies to be developed.  相似文献   

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Context

Landscape ecologists are often interested in measuring the effects of an environmental variable on a biological response; however, the strength and direction of effect depend on the size of the area within which the environmental variable is measured. Thus a central objective is to identify the optimal spatial extent within which to measure the environmental variable, i.e. the “scale of effect”.

Objectives

Our objectives are (1) to provide a comprehensive summary of the hypotheses concerning what determines the scale of effect, (2) to provide predictions that can be tested in empirical studies, and (3) to show, with a review of the literature, that most of these predictions have so far been inadequately tested.

Methods

We propose 14 predictions derived from five hypotheses explaining what determines the scale of effect, and review the literature (if any) supporting each prediction. These predictions involve five types of factors: (A) species traits, (B) landscape variables, (C) biological responses (e.g. abundance vs. occurrence), (D) indirect influences, and (E) regional context of the study. We identify methodological issues that hinder estimation of the scale of effect.

Results

Of the 14 predictions, only nine have been tested empirically and only five have received some empirical support. Most support is from simulation studies. Empirical evidence usually does not support predictions.

Conclusions

The study of the spatial scale at which landscape variables influence biological outcomes is in its infancy. We provide directions for future research by clarifying predictions concerning the determinants of the scale of effect.
  相似文献   
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猪、禽日粮的传统赖氨酸添加源是盐酸L 赖氨酸。但是 ,如今有了另一种赖氨酸源 ,这种新赖氨酸源在经济上可比传统的盐酸L 赖氨酸更为合算。这种新赖氨酸源是一种干燥的颗粒状产品 ,其中含硫酸L 赖氨酸和发酵副产品 ,由谷氨酸棒状杆菌(Corynebacteriumglutamicum)发酵产生 ,产地为美国内布拉斯加州。其商品成品提供 60 %盐酸L 赖氨酸的赖氨酸替代值。此外 ,其发酵副产品还含有盐酸L 赖氨酸中不含的其它氨基酸、磷和能量 (表 1 )。美国已用猪和肉鸡对其进行了硫酸L 赖氨酸和盐酸L 赖氨酸的比较试验。最近在美…  相似文献   
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Nonneurogenic incontinence was observed in a 1-year-old Pekingese X Poodle with female pseudohermaphroditism. The dog had male external genitalia as well as a well-developed vagina, uterus, and ovaries. Urinary incontinence was caused by an anomalous communication of the prostatic urethra with the vagina. Ovariohysterectomy and surgical correction of the urethrovaginal fistula was followed by remission of urinary incontinence. Subsequently, the dog developed estrogen responsive urinary incontinence. Nonneurogenic incontinence to be a common finding in canine pseudohermaphroditism associated with abnormalities of the vagina or urethra (or both). Surgical correction should be considered to correct anomalous communications between the genital and lower urinary tracts.  相似文献   
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