Mountain bluebirds: experimental evidence against altruism     

Power HW 《Science (New York, N.Y.)》1975,189(4197):142-143

The frequency of true altruism in nature requires assessment because, if true altruism is common, Darwin's theory of natural selection is inadequate to account for all of evolution. An experiment provided birds with the opportunity to behave truly altruistically. One member of each of 25 wild pairs was collected. Ten of these were replaced naturally by courting birds, or consorts. Only one consort fostered the young of her prospective mate, and her behavior was interpretable as a reproductive error. Other consorts behaved reproductively selfishly.  相似文献   

背靠背换流站换相失败仿真分析          下载免费PDF全文

余晓鹏  蒋建东  张博  周勇   《西南大学学报(自然科学版)》2016,38(5):182-186

开展背靠背系统换相失败的研究,对防止换相失败的发生及减小换相失败对系统运行的影响具有十分重要的意义.介绍了换相失败及引起换相失败的原因,分析了换相失败的过程.在PSCAD/EMTDC中对灵宝换流站换相失败进行了仿真,分析了换相失败后直流电压、直流电流、直流功率、逆变侧交流母线电压、整流侧触发角、逆变侧关断角的变化情况.仿真结果可以为制定避免换相失败或控制换相失败发展的措施提供参考.  相似文献   

Equine muscle fiber types: A histological and histochemical analysis of select thoroughbred yearlings     

David A. Barlow Ph.D.  Judith M. Lloyd B.S.  HT  Paul Hellhake B.S.  Jeffrey A. Seder J.D.  M.B.A. 《Journal of Equine Veterinary Science》1984,4(2):60-66

Equine skeletal muscle was histologically and histochemically analyzed in orderto measure fiber composition. Well-sampled open muscle biopsies were obtained from the semitendinosus muscle in select yearling Thoroughbreds. Each biopsy was sectioned and stained for the Harris Hematoxylin and Eosin and the modified Gomori Trichrome in order to demonstrate the basic muscle fiber morphology delineating intra and extracellular elements. A thirdstain, CA++ activated myosin Adenosine Triphosphatase at pH 9.4 was used to differentiate between specific types on the basis of enzyme activities. Subsequent differentiation of Type I slow twitch and Type II fast twitch muscle fibers was assessed on the basisof staining intensity. The high predominance of Type II fast twitch fibers ranged from 85.1 to 100 % with a mean of 90.5 %. Racing records, as two- and three-year-olds, were monitored in order to qualitatively compare histochemical results with performance achievements. While caution must be exercised, results of this investigation suggested that it may be possible, at an early age to partially predict the potential of each horse to adapt to training and to compete successfully in races of varying distances.  相似文献   

Use of etretinate for treatment of primary keratinization disorders (idiopathic seborrhea) in cocker spaniels, west highland white terriers, and basset hounds.     

H T Power  P J Ihrke  A A Stannard  K Q Backus 《Journal of the American Veterinary Medical Association》1992,201(3):419-429

An open clinical trial was used to evaluate the synthetic retinoid, etretinate, for treatment of idiopathic seborrhea in Cocker Spaniels, West Highland White Terriers, and Basset Hounds. Clinical and histologic improvement was seen in the Cocker Spaniels. Etretinate had no beneficial effect on the skin disease of the West Highland White Terriers or the Basset Hounds. Etretinate treatment did not alter the type or degree of otitis externa. Clinical side effects were minimal. Relevant laboratory abnormalities were not detected.  相似文献   

An outbreak of ringworm in sheep in Ireland caused by Trichophyton verrucosum     

S B Power  A Malone 《The Veterinary record》1987,121(10):218-220

An outbreak of ringworm in sheep in Ireland caused by Trichophyton verrucosum is described. The flock consisted of 110 sheep and two separate groups within the flock were affected. Eleven of the first group of 23 sheep and five of the second group of 25 sheep showed lesions. Contact with infected cattle and fomites contaminated by the cattle are believed to have caused the outbreak. An excellent response was obtained in both infected groups by treatment with griseofulvin at a dose rate of 7.5 mg/kg daily for seven days.  相似文献   

Long-term use of cyclosporine in the treatment of canine atopic dermatitis     

Radowicz SN  Power HT 《Veterinary dermatology》2005,16(2):81-86

This retrospective study of 51 dogs with atopic dermatitis (AD) treated with cyclosporine (CsA) for a minimum of 6 months assessed the frequency of dosing and the need for continual treatment to control clinical signs. The study evaluated both medical records and information supplied by the owners in the form of written questionnaires and telephone follow-up. Laboratory parameters, possible adverse effects and owner satisfaction were assessed. The dose of CsA was 5 mg/kg orally per day and dogs received CsA for 6-30 months. At the conclusion of the study period, 28 dogs (55%) needed ongoing CsA to control clinical signs of AD: 8 (15%) received CsA 2-3 days per week, 10 (20%) 4-5 days per week, and 10 (20%) daily. CsA was discontinued in 23 dogs (45%) after 6-24 months due to either a limited response (22%) or after achieving a clinical response (24%). The results suggest that some dogs with AD treated with CsA may not require daily or even ongoing treatment to control clinical signs. Laboratory abnormalities were detected in 13 dogs (25%) during their CsA treatment. Two dogs developed oral growths and three developed hirsuitism. Forty owners (78%) reported no adverse events in their dogs during the treatment period. Thirty-six owners (71%) were satisfied with CsA as treatment for their atopic dog.  相似文献   

Book reviews     

Elaine Power  Wm. Alex McIntosh  Susan James 《Agriculture and Human Values》1994,11(4):105-108

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Pestivirus is a common contaminant in maedi-visna and caprine arthritis-encephalitis virus stocks.          下载免费PDF全文

R A Heckert  C A Power    M R Briscoe 《Canadian journal of veterinary research》1992,56(4):370-372

Eight different laboratory stocks of maedi-visna or caprine arthritis-encephalitis virus were examined for the presence of pestiviruses by a fixed-cell immunoperoxidase assay with polyclonal and monoclonal antibodies. All of the viral stocks examined were found to contain noncytopathic pestivirus contaminants. The panel of monoclonal antibodies could not type the isolates as being more related to bovine virus diarrhea virus or border disease virus. However, the results did indicate that all isolates were not the same, except for two from the same laboratory where the source of pestivirus contamination may have been common.  相似文献   

Pemphigus foliaceus in 91 dogs     

Mueller RS  Krebs I  Power HT  Fieseler KV 《Journal of the American Animal Hospital Association》2006,42(3):189-196

A retrospective study of 91 dogs with pemphigus foliaceus was performed. Clinical signs of the disease included crusts (n=79), pustules (n=36), and alopecia (n=33). Lesions were most common on the trunk (n=53), inner pinnae (n=46), face (n=37), and foot pads (n=32). Cytological evaluation revealed acantholytic keratinocytes in 37 of 48 dogs. Results of combination treatment with prednisolone and azathioprine were comparable to results with prednisolone therapy alone. More than half of the dogs achieved remission with appropriate therapy, and another 25% significantly improved.  相似文献   

Serological status of Canadian cattle for brucellosis,anaplasmosis, and bluetongue in 2007–2008     

Julie Paré  Dorothy W. Geale  Maria Koller-Jones  Kathleen Hooper-McGrevy  Elizabeth J. Golsteyn-Thomas  Christine A. Power 《The Canadian veterinary journal. La revue veterinaire canadienne》2012,53(9):949-956

A national bovine serological survey was conducted to confirm that the prevalence of brucellosis, bluetongue, and anaplasmosis does not exceed 0.02% (95% confidence) in live cattle in Canada. Sampling consisted of a systematic random sample of 15 482 adult cattle slaughtered in federally inspected abattoirs, stratified by province. Samples were tested to detect antibodies for brucellosis, bluetongue, and anaplasmosis. All samples were negative for brucellosis. Three samples were seroreactors to bluetongue, 2 of which originated from the Okanagan Valley in British Columbia and 1 from Ontario, which after follow-up, was considered an atypical result. A total of 244 samples were seroreactors to Anaplasma and follow-up identified infection in Saskatchewan, Manitoba, and Quebec. In conclusion, the Canadian cattle population remains free of brucellosis and free of bluetongue outside the Okanagan Valley. Canada is no longer free of anaplasmosis and will be unable to claim freedom until eradication measures are completed.  相似文献