Pharmacokinetics of subcutaneous selenium in adult llamas     

Waldridge BM  Duran SH  Ravis WR  Paxton R  Herdt TH  Pugh DG 《Veterinary therapeutics : research in applied veterinary medicine》2004,5(4):272-278

Selenium (Se) deficiency disease has been described in camelids and only clinical data is available for administration of parenteral Se supplements. This study investigated the pharmacokinetic effects of subcutaneous Se injection (0.1 mg/kg) in llamas fed a diet adequate in Se. Absorption of Se was rapid with peak whole blood Se concentration at the first sampling time. Significant differences in whole blood Se concentration from before injection of Se were not found past 2 days after Se injection. Parenteral Se is unlikely to have a long-term effect on whole blood Se concentration in llamas fed adequate dietary Se.  相似文献   

PetPEP questions     

Paxton D 《Australian veterinary journal》2000,78(9):598

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Feral pigs--the time bomb     

Paxton D 《Australian veterinary journal》2002,80(5):305; author reply 305

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Grid soil sampling adoption and abandonment in cotton production     

Jonathan C. Walton  Roland K. Roberts  Dayton M. Lambert  James A. Larson  Burton C. English  Sherry L. Larkin  Steven W. Martin  Michele C. Marra  Kenneth W. Paxton  Jeanne M. Reeves 《Precision Agriculture》2010,11(2):135-147

Technology adoption in precision agriculture has received considerable attention, while abandonment has received little. Survey data are now available to evaluate adoption and abandonment decisions. Understanding the factors motivating technology adoption and abandonment has implications for educational efforts directed toward improving the efficiency of production inputs and for research and development to improve the value of precision agriculture technologies. The objective of this research was to identify factors motivating the adoption and abandonment of grid soil sampling in precision cotton production. These decisions were evaluated assuming a random utility model. Data were obtained from a 2005 survey of cotton producers in 11 Southeastern states in the USA. Results from limited dependent variable regressions indicate that younger producers who farmed more cotton area, owned more of their cropland, planted larger amounts of non-cotton area, used a computer for farm management and used a Personal Digital Assistant (PDA) in the field were more likely to adopt grid soil sampling for cotton precision farming. Results also suggest that producers with more cotton area who owned livestock and adopted management zone soil sampling were more likely to abandon grid soil sampling, while those who used a PDA in the field, used grid soil sampling for more years and followed up grid soil sampling with variable-rate fertilizer application were less likely to abandon grid soil sampling for cotton production.  相似文献   

Factors affecting farmer adoption of remotely sensed imagery for precision management in cotton production     

James A. Larson  Roland K. Roberts  Burton C. English  Sherry L. Larkin  Michele C. Marra  Steven W. Martin  Kenneth W. Paxton  Jeanne M. Reeves 《Precision Agriculture》2008,9(4):195-208

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长武和淳化两县水土保持减沙效益     

黄河中游治理局和陕西省水土保持局联合调查组 《水土保持通报》1989,(1):57-62

陕西省长武、淳化两县水土保持工作开展较好,获得了明显的经济效益和减沙效益。本文介绍了长武县鸭儿沟、淳化县冶峪河、润镇沟等流域,通过观测资料分析计算,证明1972年以后13年比1971年以前11年输沙量减少30—70%;而输沙量的减少,既不是水库拦沙的作用,也木是由于降雨偏小,而主要是由于各项水土保持措施减轻了土壤侵蚀的结果。  相似文献   

后水河水库大坝的稳定分析     

王耐力  杨卫中 《中国农村水利水电》1996,(6):36-38

对后水河水库大坝进行了分析，在坝体不设置伸缩缝，且坝基与基岩的结合处理较好时，大坝抗滑稳定属整体抗滑稳定问题，并可采用抗剪断公式进行计算及核核，可以减小坝体断面，有一定的经济效益。  相似文献   

Creep in chipboard     

J. M. W. Dinwoodie  J.-A. Higgins  D. J. Robson  B. H. Paxton 《Wood Science and Technology》1990,24(2):181-189

Summary 4- and 5-parameter rheological models were used to pedict deflections at from 7 to 10 years from 24 weeks data. Comparison with actual deflection confirmed the unsuitability of the 4-parameter model as a predictive tool, while the range in prediction errors over 20 specimens for the 5-parameter model was +23% to -26%. The standard error, though not the mean prediction error was reduced by approximately one half by extending the data accumulation period to 39 weeks. Thus the 95% confidence limits in predicting deflections at 2,555 days (7 years) from 39 weeks data was +13% to -20% for all data, and +6% to -19% for data at 20 °C, 65% r.h.  相似文献   

Creep in chipboard     

J. M. Dinwoodie  B. H. Paxton  C. B. Pierce 《Wood Science and Technology》1981,15(2):125-144

Summary The effect of moisture and level of stressing on the rate of creep and time to failure is studied for UF and MUF bonded particleboard. Response curves were fitted to a 4-element rheological model with a high degree of accuracy for four levels of stressing and for three levels of relative humidity at 20°C. Values of relative creep increased with time and also with increased levels of stress and r.h. The ratio of stress to deflection — presented either as the creep modulus or as isochronous curves — decreased rapidly with time. Particleboard is demonstrated to exhibit non-linear viscoelastic properties, particularly at the higher levels of stress. Deflection was increased and time to failure decreased when r.h. was raised from 65 to 90 per cent, but no significant statistical change was noted between 30 and 65 per cent r.h. Increased levels of stress caused a decrease in both deflection and time to failure. Greater deflection at failure and longer time to failure were recorded for MUF board, but for the UF board the 90 per cent r.h. had a more pronounced effect in increasing deflection and decreasing the time to failure. Predictions are made on the long-term stress loadings for different humidity conditions.  相似文献   

Creep in chipboard     

J. M. Dinwoodie  J. -A. Higgins  B. H. Paxton  D. J. Robson 《Wood Science and Technology》1991,25(5):383-396

Summary Samples of five chipboards, one waferboard, one plywood, one fibre building board and redwood timber (Pinus sylvestris) were loaded in 4-point bending under four stress levels: 30, 45, 67.5 and 75% of the short term ultimate, thereby extending earlier work at 60% stress level. Five environmental conditions were used at each stress level: 10°C 62% relative humidity (rh); 20°C 30% rh; 20 °C 65% rh; 20°C 90% rh and 30°C 68% rh. Deflections were recorded at least on a daily basis for a period of 6 months, unless failure of the sample occurred earlier. Values for the elastic, viscoelastic and viscous components of creep deflection were calculated for two time periods using the 4-element rheological model developed in an earlier paper: comparisons were made on the basis of the percentage contribution of each component. The relative proportions of the elastic, viscoelastic and viscous components making up total deflection were found to vary considerably with time, temperature, relative humidity, stress level and material. The relationships were complex with strong interactions occurring among environmental condition, stress level and material. Thus, for example, the effect of high temperature, or high relative humidity, in determining the magnitude of the viscous component was much greater at higher levels of stressing: waferboard appeared to be less sensitive to high humidity and solid timber more sensitive to high temperature than the other materials. T-tests further confirmed the complexity of the relationships. It is concluded that much of the variability in creep deflection recorded in Part 8 of this series is primarily due to changes in the percentage contribution of the viscous component.  相似文献