排序方式： 共有42条查询结果，搜索用时 15 毫秒
1.
2.
3.
H. T. Epp 《Water, air, and soil pollution》1995,82(1-2):179-188
A major objective of environmental impact assessment (EIA) is prediction. Two major goals in science are: (1) explanation of observed phenomena, and (2) prediction. The EIA process makes use of the methods of academic science to provide the explanatory framework for the required data gathering which is needed for the scientifically valid prediction of effects. Follow-up monitoring after a development proceeds is required to test the predictions for their accuracy, important in both scientific and decision-making aspects of EIA. This testing is needed not only for future EIAs in the area, but also for ongoing project management. In boreal forest management, where EIA prediction is ecosystem-oriented rather than site-specific only, the EIA process needs to be tied to long-term, ecosystem-based forest management plans. This must be done via ongoing tests of predictions, and then by feeding the test-derived information back into a dynamic decisionmaking process. In Saskatchewan this unique and holistic application of the EIA process to long-term forest ecosystem management has been initiated by applying EIA to the twenty-year management plan required by the holder of any forest management agreement (FMA). This is an example of harnessing scientific predictive and testing capacity of the EIA process to set the stage for ecologically sustainable, integrated forest resource management. This also is an example of local action to address a global problem by ensuring the continued integrity of ecological processes in a portion of Canada's boreal forest. 相似文献
4.
Our review has emphasized that AI tools are programming languages inspired by some problem-solving paradigm. We want to underscore their status as programming languages; even if an AI tool seems to fit a problem perfectly, its proficient use still requires the training and practice associated with any programming language. The programming manuals for PC-Plus, Smalltalk/ V, and Nexpert Object are all tutorial in nature, and the corresponding software packages come with sample applications. We find the manuals to be uniformly good introductions that try to anticipate the problems of a user who is new to the technology. All three vendors offer free technical support by telephone to licensed users. AI tools are sometimes oversold as a way to make programming easy or to avoid it altogether. The truth is that AI tools demand programming-but programming that allows you to concentrate on the essentials of the problem. If we had to implement a diagnostic system, we would look first to a product such as PC-Plus rather than BASIC or C, because PC-Plus is designed specifically for such a problem, whereas these conventional languages are not. If we had to implement a system that required graphical interfaces and could benefit from inheritance, we would look first to an object-oriented system such as Smalltalk/V that provides built-in mechanisms for both. If we had to implement an expert system that called for some mix of AI and conventional techniques, we would look first to a product such as Nexpert Object that integrates various problem-solving technologies. Finally, we might use FORTRAN if we were concerned primarily with programming a well-defined numerical algorithm. AI tools are a valuable complement to traditional languages. 相似文献
5.
The present study investigated the effects of pre‐weaning energy substitutions on follicular development, endocrine characteristics and subsequent litter size in primiparous sows. Sows were fed a standard lactation diet (14.1 DE MJ/kg) and then allocated to a Control (C, n = 24), Fat (F, n = 23), Sugar (S, n = 23) or post‐weaning Regumate (positive control; R, n = 22) treatment at 9 days before weaning of the C, F and S treatments. During the treatment period (8 days), 1 kg of the lactation diet was substituted with 1 kg of a fat‐rich (F, 23.85 DE MJ/kg) or sugar‐rich (S, 15.75 DE MJ/kg) substitution for F and S sows, respectively. For the R treatment, sows were weaned 8 days earlier than other treatments and fed a lactation diet at 3.5 kg with two doses of altrenogest as topdressing from 1 day before weaning until the day on which the other sows were weaned. The F treatment aimed to increase energy intake, and the S treatment aimed to elevate post‐prandial glucose and insulin concentrations. Weaning‐to‐ovulation interval tended to be reduced in the S treatment compared with C (p = 0.06) and F (p = 0.08) treatments. Body weight (BW) loss during the treatment period, post‐weaning follicle development, plasma oestradiol and pre‐weaning leptin did not differ among C, F and S sows, although BW loss was lower and leptin was higher in the R treatment. Post‐ovulatory progesterone concentration in the S treatment was higher (p < 0.05). Sows in the S and R treatments had a greater proportion of litters with larger litter sizes (p < 0.05). The outcome suggests that increasing circulating insulin and glucose concentrations during late lactation or a week of metabolic recovery positively improves subsequent litter size in primiparous sows. 相似文献
6.
This field study investigated whether the administration of a single dose of gonadotropin‐releasing hormone (GnRH) to dairy cows without a corpus luteum (CL) 4 weeks after calving can improve reproductive performance. Holstein dairy cows underwent ultrasonography to assess the presence of ovarian structures at 29.2 ± 5.2 days post‐partum, and cows were divided into two main groups based on the presence (CL group, n = 230) or absence (non‐CL group, n = 460) of a CL. The non‐CL group was further randomly divided into two subgroups based on the administration of GnRH (non‐CL GnRH group, n = 230) or no GnRH (non‐CL control group, n = 230). Subsets of cows from non‐CL control (n = 166) and non‐CL GnRH (n = 175) groups received a second ultrasonography at 44.5 ± 5.4 days post‐partum to assess CL formation. The percentage of cows with CL at the second ultrasonography was greater in the non‐CL GnRH group (70.9%) than in the non‐CL control group (53.0%, p = 0.0006). The hazard of the first post‐partum insemination by 150 days in milk (DIM) was higher in the CL group than in the non‐CL control group (hazard ratio [HR]: 1.36, p = 0.001). The probability of a pregnancy to the first insemination was higher in non‐CL GnRH (odds ratio [OR]: 1.50, p = 0.04) and CL groups (OR: 1.55, p = 0.03) compared to the non‐CL control group. Furthermore, the hazard of pregnancy by 210 DIM was higher in non‐CL GnRH (HR: 1.30, p = 0.01) and CL (HR: 1.51, p = 0.0001) groups than in the non‐CL control group. In conclusion, administration of GnRH to dairy cows without a CL 4 weeks after calving was associated with an increase in ovulation and improved reproductive performance. 相似文献
7.
Elevating glucose and insulin secretion by carbohydrate formulation diets in late lactation to improve post‐weaning fertility in primiparous sows 
下载免费PDF全文
下载免费PDF全文 TY Chen D Lines C Dickson C Go RN Kirkwood P Langendijk 《Reproduction in domestic animals》2016,51(5):813-818
Primiparous (P1) sows commonly lose excessive body reserves to meet energy requirements for maintenance and milk production during lactation, and consequently, post‐weaning reproductive performance may be compromised. The present studies determined whether ad libitum feeding a glucogenic carbohydrate diet (CHO) during late lactation could stimulate insulin and glucose secretion (experiment 1) and improve subsequent litter size (experiment 2). For experiment 1, 15 P1 sows, and for experiment 2, 99 P1 sows (198.5 ± 2.7 kg) were allocated randomly according to suckled litter size (≥10 piglets), either to a CHO diet (14.3 MJ DE/kg, 19.8% crude protein) or a standard lactation diet (control; 14.2 DE MJ/kg, 19.5% crude protein) at 8 days before weaning. The CHO diet aimed to provide glucogenic content (extruded wheat, dextrose and sugar) as energy sources instead of fat sources without changing total dietary energy. Pre‐prandial plasma glucose and insulin concentrations were not influenced by treatments. However, post‐prandial plasma glucose and insulin concentrations and their peaks were both higher (p < .05) compared to the control treatment. Body weight loss during lactation was relatively low at 3%–4% for both treatments and did not differ between control and CHO treatments (?7.6 ± 1.6 vs ?5.4 ± 1.2 kg; p > .05). Second litter size was not influenced by diet (p > .05), but the weaning‐to‐mating interval was shorter in CHO sows (p < .05). This study demonstrates that providing an enriched CHO diet in late lactation did influence post‐weaning follicle growth but did not improve subsequent litter size. This may be due to the primiparous sows in this study not experiencing severe negative energy balance and there was no second litter syndrome in this farm which limited the ability of diet to improve sow fertility. 相似文献
8.
Corrigan RL Waldner C Epp T Wright J Whitehead SM Bangura H Young E Townsend HG 《Preventive veterinary medicine》2006,76(3-4):263-272
In 2003, an outbreak of West Nile virus (WNV) occurred in Saskatchewan, Canada from July to September. One-hundred thirty-three horse cases and 947 human cases were recorded and data were analyzed retrospectively for evidence of clustering to determine if clinical infection in the horse population could be used to estimate human risk of infection with WNV. Kulldorff's scan statistic was used to identify spatial-temporal clusters in both the human and horse cases. In most areas, human clusters were not preceded by horse clusters. In one area, a significant cluster of horse cases preceded human cases by 1 week; however, 1 week does not provide sufficient time for human-health authorities to act and provide advance warning for the public. 相似文献
9.
Epp T Waldner C Argue CK 《The Canadian veterinary journal. La revue veterinaire canadienne》2010,51(9):973-978
In 2006, an outbreak of anthrax in Saskatchewan affected several species but most of the losses occurred in cattle. Potential risk factors contributing to this outbreak were investigated through questionnaires involving 117 case farms and 259 control farms geographically representative of the Saskatchewan beef herd. The occurrence of flooding [odds ratio (OR) = 3.4; 95% confidence interval (CI): 1.8 to 6.4], wetter pastures (Good: OR = 3.5; 95% CI: 1.4 to 8.5; Wet: OR = 7.2; 95% CI: 2.9 to 18.1), shorter pasture grass length (OR = 3.0; 95% CI: 1.4 to 6.4), and higher density of the animals on pasture (OR = 3.0; 95% CI: 1.6 to 5.7) were more likely to have been reported for case herds than for control herds. Case farms were more likely than control farms to have vaccinated more than 1 week after the first reported case in the rural municipality (OR = 6.3; 95% CI: 2.6 to 15.3). Timing of vaccination in case herds was also significantly associated with the occurrence of subsequent deaths on these farms (P = 0.001). 相似文献
10.
The objective of this study was to develop a model using equine data from geographically limited surveillance locations to predict risk categories for West Nile virus (WNV) infection in horses in all geographic locations across the province of Saskatchewan. The province was divided geographically into low-, medium-, or high-risk categories for WNV, based on available serology information from 923 horses obtained through 4 studies of WNV infection in horse populations in Saskatchewan. Discriminant analysis was used to build models using the observed risk of WNV in horses and geographic division-specific environmental data as well as to predict the risk category for all areas, including those beyond the surveillance zones. High-risk areas were indicated by relatively lower rainfall, higher temperatures, and a lower percentage of area covered in trees, water, and wetland. These conditions were most often identified in the southwest corner of the province. Environmental conditions can be used to identify those areas that are at highest risk for WNV. Public health managers could use prediction maps, which are based on animal or human information and developed from annual early season meteorological information, to guide ongoing decisions about when and where to focus intervention strategies for WNV. 相似文献