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61.
G N Taylor L Shabestari W Angus R D Lloyd C W Mays 《American journal of veterinary research》1979,40(9):1316-1318
The age-specific frequency of 11 primary pulmonic neoplasms in a closed Beagle colony is presented. The first tumor occurred at 5 years, and the frequency increased progressively in the older age classes. All of the tumors arose from sites distal to the principal bronchi. Although metastases appeared to occur relatively late, with respect to course of tumor development, they were noted in approximately a half of the dogs and most frequently involved the bronchial lymph nodes. 相似文献
62.
A method for the evaluation of Mycobacterium bovis purified protein derivative (PPD) tuberculin in experimentally infected cattle is presented. The development of skin test responses in M bovis-infected cattle was determined for International Standard PPD-S, M bovis PPD-2, and M bovis PPD-5 at 24, 48, and 72 hours. Significantly larger reactions (dermal thickness) were observed at 48 and 72 hours than at 24 hours (P = 0.001). Statistically significant differences were not detected in the responses obtained with M bovis PPD-2, M bovis PPD-5, and International Standard PPD-S if comparisons were made at approximately the same concentrations in M bovis-infected cattle (P greater than 0.25). In Mycobacterium avium-infected cattle, M bovis PPD-2 produced skin test responses that were significantly smaller than responses obtained using M avium PPD-2 (P = 0.001). Significant variation was not observed in the PPD-S responses in 2 groups of M bovis-infected cattle (P greater than 0.1). 相似文献
63.
Zaw Win Tu Tu Campbell Angus Soares Magalhães Ricardo J. Oo Kyaw Naing Henning Joerg 《Tropical animal health and production》2019,51(3):643-654
Tropical Animal Health and Production - The central dry zone of Myanmar is the area with the highest density of small-scale livestock farmers under harsh environmental condition. In this study, we... 相似文献
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The attenuation of Escherichia coli and total coliform from secondary treated wastewater effluent under two “at-grade” effluent distribution systems was evaluated
in a sandy silt vadose zone in a cold climate. The two at-grade distribution lines had different designs and hydraulic loading
rates. Effluent transport was examined using chloride as a tracer. Coliform fate was evaluated relative to the chloride using
a combination of in situ pore water sampling and destructive soil sampling, combined with the observation of a dye tracer
along excavation sidewalls. Although bacteria attenuation in the subsoil appeared to decrease during colder, winter temperatures
(likely due to decreased viability and decreased predation), the subsoil provided about a four log reduction in E. coli over 90 cm of vertical transport. Horizontal transport of bacteria (up to 1.5 m from the line) was likely aided by flow on
top of a microbial biomat observed at the soil surface. Both the subsurface dye patterns and the E. coli sampling suggested less preferential flow occurred below the lower loading rate design. At-grade distribution of secondary
treated wastewater appears to be a viable alternative to conventional distribution fields at sites with similar climate and
soils. 相似文献
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Electrically coupled inhibitory interneurons dynamically control network excitability, yet little is known about how chemical and electrical synapses regulate their activity. Using two-photon glutamate uncaging and dendritic patch-clamp recordings, we found that the dendrites of cerebellar Golgi interneurons acted as passive cables. They conferred distance-dependent sublinear synaptic integration and weakened distal excitatory inputs. Gap junctions were present at a higher density on distal dendrites and contributed substantially to membrane conductance. Depolarization of one Golgi cell increased firing in its neighbors, and inclusion of dendritic gap junctions in interneuron network models enabled distal excitatory synapses to drive network activity more effectively. Our results suggest that dendritic gap junctions counteract sublinear dendritic integration by enabling excitatory synaptic charge to spread into the dendrites of neighboring inhibitory interneurons. 相似文献
68.
Trade in wildlife resources is permitted and regulated by national and international governance. Focussing on the trade in chameleons from Madagascar, our objective was to investigate the consequences of changes in governance on the number of individuals and species traded together with the prices paid to collectors, intermediaries and exporters. As a result of the liberalisation of export controls in 1988, exports of chameleons grew exponentially at an average rate of 62% per annum, the trade in Calumma spp. increasing at 91% per annum. The intervention of CITES in 1994, as a result of concerns over the trade, capped official exports at approximately 20,000 per annum and also restricted the trade to four species of Furcifer. The consequence of the CITES intervention was a shift in the species exported from a mix of Calumma harvested in the east and Furcifer harvested in the west to a trade in Furcifer alone, alongside an increase in the number of Furcifer exports. Consequently there was a shift in the distribution of local benefits gained from the trade away from the rainforests in the east, the centre of conservation concern. At the same time there was also a fall in the prices paid to collectors and intermediaries involved in the trade and a widening of the gap with the prices paid to exporters. The creation of an Experimental Management Programme within Madagascar to address the concerns of CITES in 1998/1999 and lobby for some expansion of the trade, led to an initial fall in the number of chameleons traded. Failure to achieve the latter objective has more recently led to an increase in the number of species traded and a further widening of the prices paid to collectors and exporters. These results highlight the need to consider carefully the consequences of changes in governance on the wildlife trade if conservation and local people are to benefit from the trade in wildlife resources. 相似文献
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70.
Spatial weighting of land use and temporal weighting of antecedent discharge improves prediction of stream condition 总被引:1,自引:0,他引:1
Land management to protect streams requires knowing which parts of the landscape most strongly influence stream condition. Understanding how flow through landscapes and along streams affects such land-use impacts requires knowing the period of antecedent discharge that most strongly influences condition. Both considerations require determination of optimal weighting schemes for predictors of stream condition. We calculated forest cover weighted by flow-path distance to 572 urban, peri-urban, and rural sites—in the Melbourne, Australia, region—sampled for macroinvertebrates, and antecedent discharge weighted by time preceding each of 1,723 samples. Using mixed linear models that accounted for spatial dependence, we aimed to determine the weighting curve shape and length that best predicted macroinvertebrate assemblage composition. The best model was a function of mean annual discharge, weighted forest cover, weighted imperviousness, weighted antecedent discharge, and their interactions. Optimal weightings were exponential—half-decay distance 35 m overland (plausible range 26–50 m), and 1.0 km in-stream (0.75–1.3 km) for forest cover—, and linear over ≥4 year for antecedent discharge. Model plausibility was more affected by weighting distance than the shape of the weighting function. Regardless of weighting curve shape, riparian forest effects on macroinvertebrate assemblages are strongest within 101–102 m from the stream, and 103 m upstream. Although exponential weightings are only marginally more plausible, they are the most realistic representation of physical processes. While our conclusions should not be interpreted as recommendations for buffer widths, they provide valuable insight into the scales of influence in the region and could be used to inform management decisions. 相似文献