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1.
The examination of the foot must be based on observations of the hoof, followed by a careful determination of areas of pain. This must be followed by an assessment of the biomechanical forces on the hoof and limb. Finally, imaging gives insight into the nature of the injury and allows the examiner to prognosticate the outcome.  相似文献   
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Ethanol can contribute to energy and environmental goals   总被引:4,自引:0,他引:4  
To study the potential effects of increased biofuel use, we evaluated six representative analyses of fuel ethanol. Studies that reported negative net energy incorrectly ignored coproducts and used some obsolete data. All studies indicated that current corn ethanol technologies are much less petroleum-intensive than gasoline but have greenhouse gas emissions similar to those of gasoline. However, many important environmental effects of biofuel production are poorly understood. New metrics that measure specific resource inputs are developed, but further research into environmental metrics is needed. Nonetheless, it is already clear that large-scale use of ethanol for fuel will almost certainly require cellulosic technology.  相似文献   
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Southern crabgrass (Digitaria ciliaris [Retz.] Koel.) is often viewed as an undesirable weed, largely because it encroaches upon field and forage crops, gardens, and lawns. However, visual observations of livestock grazing mixed-species pastures suggest that cattle seem to prefer crabgrass to many other summer forages. The objectives of this study were to assess the nutritive value of crabgrass sampled weekly between July 11, and August 22, 2001, and then to determine ruminal in situ disappearance kinetics of DM and NDF for these crabgrass forages. A secondary objective was to compare these kinetic estimates with those of alfalfa (Medicago sativa L.), bermudagrass (Cynodon dactylon [L.] Pers.), and orchardgrass (Dactylis glomerata L.) control hays. All forages were evaluated in situ using five (383 +/- 22.7 kg) ruminally cannulated crossbred (Gelbvieh x Angus x Brangus) steers. Whole-plant crabgrass exhibited more rapid (P < or = 0.002) ruminal disappearance rates of DM (overall range = 0.069 to 0.084 h(-1)) than did bermudagrass (0.054 h(-1)) and orchardgrass (0.060 h(-1)) hays, but disappearance rates were slower (P < 0.001) for crabgrass than for alfalfa hay (0.143 h(-1)). Effective ruminal disappearance of DM was greater (P < 0.001) for crabgrass (overall range = 69.3 to 75.4%) than for all the control hays. Similarly, disappearance rates of NDF for crabgrass (overall range = 0.069 to 0.086 h(-1)) were more rapid (P < 0.001) than observed for bermudagrass and orchardgrass hays; however, NDF in alfalfa disappeared at a faster (P < 0.001) rate (0.107 h(-1)) than crabgrass. These results indicate that crabgrass offers greater effective ruminal degradability of DM and NDF than orchardgrass or alfalfa of moderate quality. More importantly, it potentially offers faster and more extensive ruminal disappearance than perennial warm-season grasses typically found throughout the southeastern United States, and it should likely support improved performance by ruminant livestock in this region.  相似文献   
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A passage line of a spontaneous hamster fibrosarcoma is contaminated by the virus. of lymphocytic choriomeningitis. Tumors from animals receiving implants when newborn contain high titers of infectious lymphocytic-choriomeningitis virus and complement-fixing antigen, and hamsters receiving implants when weanlings develop high titers of complement-fixing antibody against lymphocytic-choriomeningitis virus. In contrast with the specific reactions of tumorous hamsters to the initiating virus in virus-induced tumors, the development of complement-fixing antibody to lymphocytic-choriomeningitis virus does not depend on the development of tumors. Infant hamsters bearing the tumor have a generalized subclinical infection and seem able to spread virus to other hamsters and to humans.  相似文献   
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The present study was conducted to determine the influence of density gradient composition on in vitro capacitation of stallion spermatozoa. In Experiment I spermatozoa were isolated on either 90% Percoll (P), 90% arabinogalactan (AG), or 12% BSA gradients and then challenged with 1 μM A23187 (15, 150, and 270 min) and heat-solubilized equine zonae pellucidae (270 min, sEZP, 2 ZP/μl). The P gradient enhanced the percentage of progressively motile spermatozoa (PMS) more (P=.0001) than AG or BSA gradients immediately post-processing, but was not sustained throughout the culture period. The viability for P-separated spermatozoa was higher (P=.01) than that of BSA or AG-separated spermatozoa. Gradient composition had no effect (P=.68) on the percentage of live, acrosome reacted spermatozoa (PAR), before and following ionophore and sEZP challenge. In Experiment II, the number of spermatozoa penetrating the ZP of saltstored oocytes was not influenced (P=.35) by gradient composition; however, the number of spermatozoa bound per oocyte was higher (P=.02) for P-separated spermatozoa than for AG or BSA-separated spermatozoa. These data suggest that isolation on a P density gradient may enhance in vitro capacitation of stallion spermatozoa.  相似文献   
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This study evaluated the time course of systemic cytokine concentrations in an acute model of pneumonia in pigs challenged intranasally with Actinobacillus pleuropneumoniae. Feed intake and serum cortisol were measured as overt clinical and systemic markers of disease onset, respectively, and serum tumor necrosis factor-alpha, interleukin-1beta, and interferon-gamma as representative systemic inflammatory markers. Crossbred barrows (n = 15), approximately 5 wk of age, were used in the study. Pigs were housed in an environmentally controlled facility at 25 degrees C and under continuous illumination in pens measuring approximately 1.5 m2. Pigs had free access to water and an unmedicated diet. Approximately 1 wk prior to disease challenge, pigs were fitted nonsurgically with venous catheters. At challenge, pigs were given 5 x 10(8) CFU Actinobacillus pleuropneumoniae intranasally (n = 8) or a similar volume of sterile growth media intranasally (Control; n = 7). Feed intake was estimated by the change in feeder weight at 12-h intervals from -12 to 72 h relative to the time of disease challenge. Blood sampling began 12 h prior to challenge and continued until 72 h after challenge. Pigs were sampled at -12, -6, and 0 h, then at 90-min intervals until 12-h post-challenge, continuing at 3-h intervals until 24-h post-challenge, then again at 6-h intervals until 72 h after challenge. Serum was harvested and frozen until assayed for cortisol, tumor necrosis factor-alpha, interleukin-1beta, and interferon-gamma. Feed intake was reduced in Actinobacillus pleuropneumoniae pigs during the intervals 0 to 12 h (P < 0.001), 24 to 36 h (P < 0.001), 48 to 60 h (P <0.05), and 60 to 72 h (P < 0.05). TheActnobacillus pleuropneumoniae-challenged pigs had elevated serum cortisol from 180-min to 18-h post-challenge (P < 0.001) and also at 36 (P < 0.05), 42 (P < 0.001), and 60 (P < 0.05) h following infection. Circulating cytokines were not affected by disease challenge. Thus, in this experimental model of pneumonia, weaned pigs demonstrated expected behavioral and endocrine characteristics of disease in the absence of significant changes in circulating inflammatory cytokines.  相似文献   
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A previously developed mathematical model, which uses a comprehensive two-dimensional heat and mass transport code coupled with a three-dimensional code for resolving Maxwell's equations in the time domain, will be used to investigate numerous aspects of the microwave enhanced convective drying of softwood in an over-sized waveguide. At first, in order to highlight the predictive capabilities of the developed model, comparisons will be made between theory and experiment for spruce heartwood. It will be shown that the model is able to identify most of the important heat and mass transfer phenomena that arise throughout the drying process. After validation of the numerical simulation results, the work focuses on using the model as a cognitive tool for investigating important issues for closed microwave systems which include the effect of varying the sample dimensions and changing the location of the material within the applicator. Finally, a study will be presented that compares the overall drying kinetics generated within two different types of applicator designs. The first design uses a wave-trap located at the end of the waveguide to prevent reflected energy from back-propagating into the over-sized section of the guide, while the second design uses a short-circuit plane to ensure that this reflected energy is back – propagated towards the material. The advantages and disadvantages of these two designs will be deliberated. Received 25 May 1997  相似文献   
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