Variation of pesticide concentration in sheep dips operated according to traditional and revised methods     

Sherwood N  Watts T  Allan C  Chandler D 《Australian veterinary journal》1999,77(6):384-387

OBJECTIVE: To quantify stripping in traditional dipping operations and to revise dipping methods, based on prediction of stripping so that a more stable concentration of pesticide in the dipwash is achieved. DESIGN AND METHODS: Plunge and shower dips were operated sequentially according to traditional and revised dipping instructions. Dips were operated by continuous and intermittent replenishment. Samples of mixed dipwash were collected periodically and assayed for pesticide (diazinon) concentration. RESULTS: Diagrammatic representations of pesticide concentration versus number of sheep dipped indicated traditional dipping leads to wide variations in the concentration of pesticide in dipwash during dipping. Intermittent replenishment led to a 'saw-tooth' pattern in the pesticide concentration. Traditional continuous replenishment (using the starting concentration of pesticide) indicated both the rate and extent of stripping was higher in shower dipping. If sufficient sheep were dipped, equilibrium was reached between the rate of pesticide replenishment and removal. An alternative method of dip operation by continuous replenishment, using a low starting concentration of pesticide and a replenishment concentration high enough to offset the pesticide loss through stripping resulted in a more stable concentration of pesticide in the dip. CONCLUSION: Revision of dipping instructions can lead to exposure of sheep to stable concentrations of stripping pesticide during dipping.  相似文献   

Effects of zearalenone on the developing male chick     

R F Sherwood  J F Peberdy 《British poultry science》1973,14(1):127-129

Incorporation of 40 p.p.m. of the mycotoxin, zearalenone, into the food of male chicks for a period of 10 d, had little effect on weight gain or efficiency of food conversion, but caused a significant increase in the weight of testes and comb.  相似文献   

Rapid communication: mapping of the beta Tropomyosin (TPM2) gene to pig chromosome 1     

Sherwood J  Ciobanu D  Rothschild MF 《Journal of animal science》2002,80(5):1379-1380

  相似文献   

Pheromone-Related Inhibitors of Ustilago hordei Mating and Tilletia tritici Teliospore Germination     

Kosted PJ  Gerhardt SA  Sherwood JE 《Phytopathology》2002,92(2):210-216

ABSTRACT Ustilago hordei, the causal agent of barley covered smut, produces mating pheromones that break down to smaller peptide compounds that act as potent inhibitors of mating and germination in several fungi. The pheromones are members of the farnesylated family of proteins. Synthetic peptide analogs of the pheromone derivatives, ranging in size from 4 mers to full length pheromones, were farnesylated, methyl esterified, or both and tested for mating or teliospore germination inhibition with U. hordei or Tilletia tritici, respectively. N-Acetyl-S-farnesylcysteine, which inhibits processing of Ras, and other sulfur-containing compounds such as homocysteine or methionine, were likewise modified and tested. The most potent inhibitors were methionine methyl ester and modified 4-mer peptides from both pheromones. Alanine scanning of the inhibitory 4 mers determined that the native amino acid sequence was specific for a high level of activity. The sulfur amino acids appear to be required for inhibition. Glasshouse studies using selected antagonists of mating and teliospore germination as seed treatments inhibited covered smut of barley and common bunt of wheat, although the level of control was inconsistent. The use of pheromone-related antagonists to mating or teliospore germination is a promising, novel strategy for control of smut and bunt diseases.  相似文献   

Differential reactivity of bovine lymphocytes to species of Brucella     

R Smith  J C Kapatsa  S J Sherwood  T A Ficht  J W Templeton  L G Adams 《American journal of veterinary research》1990,51(4):518-523

The reactivity of bovine lymphocytes to 4 species of Brucella was tested in thymidine-uptake assays, using long-term cultured lymphocytes and freshly obtained blood mononuclear cells. Lymphocytes were taken from cows that had been challenge exposed with a virulent strain of B abortus at midgestation. The cows were classified retrospectively as being naturally resistant or susceptible to brucellosis. Lymphocytes taken from these cows had 3 patterns of reactivity with species of Brucella: pattern 1 was defined by reactivity with 4 species (B abortus, B canis, B suis, and B melitensis); pattern 2 was defined by reactivity with all these species, except B melitensis; pattern 3 was defined by reactivity with B abortus and B canis, but not with B suis or B melitensis. There was a statistically significant correlation between susceptibility to brucellosis and expression of lymphocyte cross-reactivity with B suis (P less than 0.01) and with B melitensis (P less than 0.001).  相似文献   

几种甘蓝型油菜幼苗抗旱性特征的比较研究     

关周博  田建华  胡银岗  李少钦  董育红  郑磊  韦世豪  塔娜  王学芳  张文学  李殿荣 《上海交通大学学报(农业科学版)》2014,21(5):46-51

以EV1、EV2、EV3、EV4、EV5、EV66个抗旱性不同的油菜品种为试验材料,通过不同浓度PEG-6000渗透溶液模拟干旱胁迫处理,研究油菜幼苗的抗旱指数、根长、苗高和根冠比等性状变化,探索在大田环境条件下的苗期生长特征。结果表明,水分胁迫下EV2的抗旱指数最大,EV6的抗旱指数最小;不同浓度PEG胁迫下,各品种差异显著, EV1、EV2、和EV3的根长、苗高和根冠比较大,而EV5和EV6的表现较差。在大田油菜五叶期时,EV2的冠层覆盖面积最大,与其它品种之间存在极显著性差异;总生物量以EV2、EV3和EV1较大,根系干重以EV2较大,而且三者之间存在显著相关性;与抗旱指数进行通径分析,冠层覆盖面积对抗旱性的直接通径系数最大,达到0.5975。冠层覆盖面积的大小反映了早期活力的强弱,早期活力强,相应的品种抗旱指数高,抗旱性强。  相似文献   

Laboratory study of SO2 dry deposition on limestone and marble: Effects of humidity and surface variables     

E. C. Spiker  R. P. Hosker Jr.  V. C. Weintraub  S. I. Sherwood 《Water, air, and soil pollution》1995,85(4):2679-2685

The dry deposition of gaseous air pollutants on stone and other materials is influenced by atmospheric processes and the chemical characteristics of the deposited gas species and of the specific receptor material. Previous studies have shown that relative humidity, surface moisture, and acid buffering capability of the receptor surface are very important factors. To better quantify this behavior, a special recirculating wind tunnel/environmental chamber was constructed, in which wind speed, turbulence, air temperature, relative humidity, and concentrations of several pollutants (SO₂, O₃, nitrogen oxides) can be held constant. An airfoil sample holder holds up to eight stone samples (3.8 cm in diameter and 1 cm thick) in nearly identical exposure conditions. SO₂ deposition on limestone was found to increase exponentially with increasing relative humidity (RH). Marble behaves similarly, but with a much lower deposition rate. Trends indicate there is little deposition below 20% RH on clean limestone and below 60% RH on clean marble. This large difference is due to the limestone's greater porosity, surface roughness, and effective surface area. These results indicate surface variables generally limit SO₂ deposition below about 70% RH on limestone and below at least 95% RH on marble. Aerodynamic variables generally limit deposition at higher relative humidity or when the surface is wet.  相似文献   

Agglomeration and Competition among Chinese Cities: An Investigation of Taiwanese High‐Tech Foreign Direct Investment     

KENG‐HSIANG CHENG  YU‐CHING CHIAO  HSIN‐YU SHIH  TAI‐YU LEE  TA‐SHUN CHO 《Growth and change》2011,42(4):517-548

The purpose of this study was to investigate how Taiwanese high‐tech firms' foreign direct investment (FDI) leads to agglomeration and competition among cities in China. By using social network analysis to analyze 1,111 subsidiaries affiliated with 270 multinational corporations (MNCs) during the years between 1988 and 2006 in 30 major Chinese cities, this study finds that: 1) agglomeration in Chinese cities falls into three primary categories: the hub cluster, the communication‐extended cluster, and the computer‐extended cluster. Among the aforementioned clusters, the hub cluster is the most critical in terms of firm location, and therefore is often a high‐priority investment site for Taiwanese high‐tech firms. 2) Chinese cities fall into four primary groups, or “blocks”: the core block, the coast block, the inland block, and the periphery block; these groups were determined by applying a structural equivalence analysis of which members of each type are in competition with one another. By linking the findings of the urban network characteristics to Chinese regional economic policies, this study provides guidance to aid executives in determining the optimal location for future FDI. Implications and suggestions for host country governments in terms of firms' investment strategies are also discussed.  相似文献   

Little evidence for developmental plasticity of adult hematopoietic stem cells     

Wagers AJ  Sherwood RI  Christensen JL  Weissman IL 《Science (New York, N.Y.)》2002,297(5590):2256-2259

To rigorously test the in vivo cell fate specificity of bone marrow (BM) hematopoietic stem cells (HSCs), we generated chimeric animals by transplantation of a single green fluorescent protein (GFP)-marked HSC into lethally irradiated nontransgenic recipients. Single HSCs robustly reconstituted peripheral blood leukocytes in these animals, but did not contribute appreciably to nonhematopoietic tissues, including brain, kidney, gut, liver, and muscle. Similarly, in GFP+:GFP- parabiotic mice, we found substantial chimerism of hematopoietic but not nonhematopoietic cells. These data indicate that "transdifferentiation" of circulating HSCs and/or their progeny is an extremely rare event, if it occurs at all.  相似文献   

Looking back to see ahead: Farmer lessons and recommendations after 15 years of innovation and leadership in Güinope, Honduras     

Stephen Sherwood  Sergio Larrea 《Agriculture and Human Values》2001,18(2):195-208

Güinope, Honduras was the site of a highly acclaimed people-centered development project in the 1980s. The ACORDE/Ministry of Natural Resource/World Neighbors Integrated Development Program (IDP) was unique for its time, since rather than relying on technology transfer, it promoted innovation skills for local generation of responses to needs. Furthermore, it was one of the first efforts in Latin America to employ villagers as principal agents of change. Fifteen years after the inception of the IDP and ten years after its completion, the authors interviewed farmers in their fields and held a series of participatory workshops over eighteen months with ten outstanding farmers who had become project leaders. The leaders identified influential factors behind their involvement and produced recommendations for rural development interventions. Further, a generalized concept map typifying ideal characteristics for farmer promoters was constructed. Recommendations for development agencies centered on project design and implementation, demanding a methodology for strengthening local innovative capacities, participation, and control over resources. Ultimately, the leaders downplayed the role of technologies in rural development and called for special attention to enabling communities to confront external pressures, in particular recent government ``modernization' policies, that they felt threatened community livelihood. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献