排序方式： 共有39条查询结果，搜索用时 15 毫秒
21.
Vincent M. Maillard Gregory D. Boardman Justin E. Nyland David D. Kuhn 《Aquacultural Engineering》2005,33(4):271-284
Studies were conducted to characterize raceway water quality, effluent water quality, and waste solids within three, raceway-type trout farms. No significant differences were found in effluent water quality between the three farms during 7 months of monitoring. Average effluent quality over the course of the day was not found to be impaired. However, effluent quality was found to change significantly during times of feeding and harvesting. In a concrete/earthen-lined farm, normalized total suspended solids (TSS) concentrations were as high as 115 and 63 mg/l during harvesting and feeding events, respectively. Total Kjeldahl nitrogen (TKN) and ortho-phosphate (OP) also increased with higher TSS loads. The majority of particles (by weight) measured in effluent samples at all three farms were evenly divided between the smallest range (1.5–30 μm) and the largest (>210 μm). For settled sludge samples, the majority of the particles were in the size range of 1.5–30 μm. Particle size in the raceway was positively correlated with fish size during feeding events, but this correlation dissipated during the 4-h period after feeding. The accumulation and characteristics of sludge in a sediment trap were also monitored over a 22-day period. 相似文献
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Boardman T Warner C Ramirez-Gomez F Matrisciano J Bromage E 《Veterinary immunology and immunopathology》2012,145(1-2):511-515
This study characterizes a monoclonal antibody (mAb) produced against the cytoplasmic tail region of the epsilon chain of the CD3 (CD3?) transmembrane protein found on T lymphocytes of rainbow trout (Oncorhynchus mykiss). Flow cytometry and fluorescent microscopy conducted on trout leukocytes with the anti-trout CD3? mAb showed a distinctive population of IgM? CD3e+ lymphocytes fitting the expected profile of T-cells. Immunoprecipitation of lysates derived from trout lymphocytes revealed a 19 kDa protein and peptide analysis confirmed its specificity for CD3?. In vitro proliferation assays with T-cell mitogens, ConA and PHA, resulted in a 3 fold increase in the percentage of CD3?+ lymphocytes compared to LPS and control cultures. The mAb characterized in this study will be useful in further elucidation for both the role and distribution of T lymphocytes in the teleost immune system. 相似文献
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Samuel?V.?Glass Charles?R.?Boardman Samuel?L.?ZelinkaEmail author 《Wood Science and Technology》2017,51(2):243-260
Recently, the dynamic vapor sorption (DVS) technique has been used to measure sorption isotherms and develop moisture-mechanics models for wood and cellulosic materials. This method typically involves measuring the time-dependent mass response of a sample following step changes in relative humidity (RH), fitting a kinetic model to the data, and extrapolating the asymptotic mass. A series of steps covering the full RH range is used to generate the sorption isotherm. The majority of prior DVS data were taken with hold times of either 60 min or until the change in moisture content was <0.002% per minute over a 10-min period. Here, DVS measurements on wood and isolated wood polymers are presented where the hold times at certain relative humidity steps were much longer, ranging between 24 and 50 h. The data clearly show that the criteria for hold time in previous DVS measurements result in significant errors in prediction of the asymptotic mass. Although the data at short times are consistent with previous measurements, the data exhibit slow sorption behavior with characteristic times on the order of 500–2000 min that cannot be identified with shorter hold times. The results suggest that new hold time criteria need to be developed for dynamic vapor sorption measurements in wood. 相似文献
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Sandra Wenger Wayne Boardman Peter Buss Danny Govender Chris Foggin 《Journal of zoo and wildlife medicine》2007,38(3):380-387
White rhinoceroses (Ceratotherium simum) anesthetized with etorphine combinations develop severe pathophysiologic changes, including hypoventilation, hypoxemia and metabolic acidosis. The aim of this study was to evaluate the addition of butorphanol to the immobilizing mixture on the cardiopulmonary effects in free-ranging white rhinoceroses darted from the helicopter. In the control group (n=15), the rhinoceroses were anesthetized with etorphine, azaperone, detomidine, and hyaluronidase administered intramuscularly. In the treatment group (n=16), 10-20 mg of butorphanol was added to the combination. Within 10 min of becoming immobile, vital parameters (heart rate, respiratory rate, and temperature) and blood gas analyses were taken, and measurements were repeated after 10 (treatment group) and 20 min (control group). Both groups showed respiratory and metabolic acidosis, hypoxemia, and hypercapnia. In the control group, the arterial partial pressure of oxygen was significantly higher and the alveolar-to-arterial oxygen pressure gradients were significantly lower in all body positions compared with the butorphanol group. Oxygen hemoglobin saturation in the control group was higher than in the butorphanol group only in the lateral position. Improvements in arterial oxygen levels were observed in all animals when placed in sternal recumbency. There were no significant differences in the mean induction times between groups, but the distance the butorphanol group ran was significantly less after darting than in the control group. By adding butorphanol to the immobilizing mixture, no benefits in ventilation were seen; although, size differences make comparisons difficult. Running for a shorter distance during induction could be beneficial in the prevention of severe acid-base imbalances and capture myopathy. 相似文献
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David D. Kuhn Gregory D. Boardman Steven R. Craig George J. Flick Jr Ewen McLean 《Journal of the World Aquaculture Society》2008,39(1):72-82
Recovering nutrients in a fish effluent to be used as a supplemental feed for shrimp culture could ease constraints (e.g., environmental issues and high production cost) that have limited the US shrimp farming industry in the past. In this study under laboratory scale conditions, fish effluent was collected from a commercial tilapia farm and nutrients from the waste stream were offered as supplemental feed as either (1) untreated solids from tilapia effluent or (2) microbial flocs generated from the biological treatment of the effluent by reducing soluble chemical oxygen demand >80%. The first feeding trial demonstrated that microbial flocs contributed significantly (P < 0.05) to overall growth while untreated solids did not. Moreover, microbial flocs were larger and contained higher levels (P < 0.05) of protein. The second feeding trial investigated different feeding rates of commercial diets with and without microbial floc supplementation. Weekly measurements of mass and specific growth rates demonstrated that microbial flocs significantly (P < 0.05) contributed to shrimp performance. Weekly food conversion ratios were also reported. Water quality in shrimp systems during both studies was within safe levels, and no differences (P > 0.05) between treatments were observed for dissolved oxygen, nitrate‐nitrogen, nitrite‐nitrogen, pH, salinity, total ammonia nitrogen, and temperature. 相似文献
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Curtailment of muddy floods in the Sompting catchment, South Downs, West Sussex, southern England 总被引：2，自引：0，他引：2
Abstract. Muddy floods due to runoff are a widespread problem on the South Downs of southern England and are associated with increased growing of autumn-sown cereals over the last two decades. The 10.6 km2 Sompting catchment has been monitored over the 12-year period 1990/91–2001/02. A housing estate at the lower end of the catchment that was frequently inundated by muddy floods in the late 1980s and early 1990s has not been flooded since the winter of 1993/94, even during the heavy rainfall events of October and November 2000. This is a result of the ameliorative measures put in place in the early 1990s, primarily the reversion of some winter cereal fields to permanent grassland (set-aside). Other land management changes helped, for example, some parts of the catchment were put down to short-term grass leys and small dams were constructed to impound runoff. Flooding of the housing estate occurred when more than 30% of the catchment was covered by eroded fields, which contributed runoff to the valley floors leading down to the housing estate. The length of continuous down-valley flow was greater in the early 1990s compared with later years. The introduction of grassland reduced the risk of flooding not only by reducing the area contributing to runoff, but also by stopping valley floor flows linking up. Such measures to alleviate runoff, erosion and flooding fit well with policies proposed in the recent report by the UK Policy Commission on the Future of Farming and Food. 相似文献
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John Boardman Karel Vandaele Robert Evans Ian D. L. Foster 《Soil Use and Management》2019,35(2):245-256
Off‐site impacts of soil erosion are of greater social and economic concern in Western Europe than on‐site impacts. They fall into two related categories: muddy flooding of properties and ecological impacts on watercourses because of excessive sedimentation and associated pollutants. Critical to these impacts is the connectedness of the runoff and sediment system between agricultural fields and the river system. We argue that well‐connected systems causing off‐site damage are not necessarily related to areas of high erosion rates; emphasis should therefore be on the way in which connections occur. In temperate, arable systems, important elements of connectivity are anthropogenic in origin: roads, tracks, sunken lanes, field drains, ditches, culverts and permeable field boundaries. Mapping these features allows us to understand how they affect runoff and modify its impacts, to design appropriate mitigation measures and to better validate model predictions. Published maps (digital and paper) do not, by themselves, give sufficient information. Field mapping and observation, aided by remote sensing, are also necessary. 相似文献
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Early drilling of autumn‐planted cereals is strongly advised in UK government publications targeted at farmers, in part as a measure to combat soil erosion by water. However, in years when rainfall is heavy in early autumn, this strategy is ineffective. Late drilling of autumn‐planted cereals also increases the risk of erosion, but for a different reason: crop cover develops more slowly in cooler weather, resulting in a longer exposure of nearly bare ground. The crucial factor affecting both strategies is the timing of autumn and early winter rainfall. We discuss a conceptual model based on the notion of a ‘window of opportunity’ for erosion, comprising the relationship between drilling date, date of attainment of a sufficiently protective crop cover and the timing of rainfall; variations are presented for different weather conditions and management choices. Of these three factors, only the date of drilling can be chosen by the farmer. The date of attaining a sufficiently protective crop cover can only be predicted approximately. The timing of rainfall cannot be predicted. Thus, erosion control advice to farmers, which is based on choice of date of drilling to minimize erosion during the ‘window of opportunity’, is both difficult to formulate and likely to be ineffective. Sites at risk of erosion need to have better thought‐out mitigation measures in place, rather than relying on a fortuitous temporal pattern of autumn and winter rainfall to minimize the risk of erosion. 相似文献