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Self-fertilization and monogenic strains in natural populations of terrestrial slugs 总被引:3,自引:1,他引:2 下载免费PDF全文
McCracken GF Selander RK 《Proceedings of the National Academy of Sciences of the United States of America》1980,77(1):684-688
Electrophoretic studies of genetic variation in 14 species of terrestrial slugs of the families Arionidae, Philomycidae, and Limacidae in the eastern United States indicate that self-fertilization, either facultative or obligatory, is the normal breeding system in six of the species. Three of these six species are single monogenic strains; one consists of three monogenic strains; one includes a highly heterozygous form and two monogenic strains; and one has a moderate amount of polymorphism but little heterozygosity and strong linkage disequilibrium. Eight species are outcrossers, being highly polymorphic and panmictic within local populations. Niche breadth, assessed in terms of extent of geographic distribution and variety of habitats occupied and measured on an experimental plot of woodland, is greater in some monogenic strains than in highly heterozygous, outcrossing species. Colonizing success apparently is independent of the amount of genetic variation carried by a species. 相似文献
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Clayton RA Henderson J McCracken SE Wigmore SJ Paterson-Brown S 《Postgraduate medical journal》2005,81(956):396-400
Objectives: To assess the experience gained by pre-registration house officers (PRHOs) at the end of their first post. To assess confidence in managing common emergencies and experience gained in practical procedures. To compare traditional six month posts with four month posts and to compare the experiences of PRHOs posted in teaching hospitals (THs) with those based in district general hospitals (DGHs). Design: Interview questionnaire. Participants: 152 graduates from Edinburgh University Medical School in 2000 who had completed their first PRHO post by February 2001. Results: There were few significant differences in confidence in managing emergencies and in numbers of practical procedures attempted between respondents from four and six month posts or between those holding TH and DGH posts. PRHOs had gained little experience in practical procedures: fewer than 15% had performed five or more of a number of procedures including lumbar puncture, pleural aspiration, chest drainage, and insertion of nasogastric tube. A high proportion of PRHOs indicated that they felt confident initiating management of conditions in specialties of which they had little or no experience. Conclusions: Rotations of three four month posts do not seem to reduce overall experience in the PRHO year. There is little difference in experience gained between TH and DGH posts. PRHOs perform few practical procedures and some may be overconfident in their own abilities. 相似文献
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A. W. McCracken 《Heart (British Cardiac Society)》1962,24(1):126-128
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Research knowledge among parents of children participating in a randomized clinical trial 总被引:1,自引:0,他引:1
Vitiello B Aman MG Scahill L McCracken JT McDougle CJ Tierney E Davies M Arnold LE 《Journal of the American Academy of Child and Adolescent Psychiatry》2005,44(2):145-149
OBJECTIVE: Parental permission is required for child research, but parents' understanding of research aims and procedures has not been well documented. Parental research knowledge was assessed during a clinical trial in autism. METHOD: Parents of 101 children (age 5-17 years) with autism participating in a placebo-controlled trial of risperidone were given a questionnaire at the end of the study. RESULTS: Of the 95 parents completing the questionnaire, 99% knew of possible placebo assignment and that testing the medication efficacy was the main purpose of the investigators; 96% to 98% knew that research involved both risks and potential benefits, identified the study medication, and knew of their right to withdraw at any time; 90% to 95% knew of the medication's main side effects; 87% reported having been informed of possible alternatives to research participation; and 72% were aware that treatment was randomly assigned (whereas 27% reported that treatment was chosen based on individual needs to ensure best care). Parents with a college degree were more likely to recognize the random nature of treatment assignment. CONCLUSIONS: Overall, parents were highly knowledgeable of the main research components. About one fourth, however, seemed unaware that treatment was randomly determined and not personalized, suggesting that therapeutic misconception may affect some otherwise well-informed parents. 相似文献
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