Richard Powell

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Belclare and Cambridge are prolific sheep breeds, the origins of which involved selecting ewes with exceptionally high litter size records from commercial flocks. The variation in ovulation rate in both breeds is consistent with segregation of a gene (or genes) with a large effect on this trait. Sterile ewes, due to a failure of normal ovarian follicle(More)
We compared the Y-chromosome linkage maps for four salmonid species (Arctic charr, Salvelinus alpinus; Atlantic salmon, Salmo salar; brown trout, Salmo trutta; and rainbow trout, Oncorhynchus mykiss) and a putative Y-linked marker from lake trout (Salvelinus namaycush). These species represent the three major genera within the subfamily Salmoninae of the(More)
We report on the construction of a linkage map for brown trout (Salmo trutta) and its comparison with those of other tetraploid-derivative fish in the family Salmonidae, including Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), and Arctic char (Salvelinus alpinus). Overall, we identified 37 linkage groups (2n = 80) from the analysis of(More)
In Northern Europe and Canada, the salmon louse, Lepeophtheirus salmonis (Krøyer), seriously affects the marine phase of salmon production. Although the problem is long-standing, the development of sustainable methods of pest management has been unable to keep pace with the intensification of production, leading to large-scale reliance on very few(More)
In a recent article in this journal, D. H. Gleaves (1996) criticized the sociocognitive model (SCM; N. P. Spanos, 1994) of dissociative identity disorder (DID) and argued in favor of a posttraumatic model (PTM) in which DID is conceptualized as a consequence of childhood abuse and other traumatic events. The present authors demonstrate that (a) many of(More)
Within species, individuals differ by gene expression, which may translate into remarkable phenotypic differences. Between species, gene expression levels change linearly over evolutionary time due to stochastic processes [1,2], while intraspecific evolution of transcriptional variation seems to be dominated by stabilizing selection [3]. We show that global(More)
Most mental health researchers rely upon quantitative methods of data collection. Whilst such methods are commonly seen as reliable, qualitative methods are often seen as more valid. Despite the value of qualitative methods of data collection, however, many researchers denigrate their use. Qualitative research is often viewed as lacking in scientific(More)
CONTEXT Although pain and burdensome symptoms among HIV-infected persons can be effectively managed, the availability of opioids and other symptom-controlling drugs is a particular challenge in sub-Saharan Africa. OBJECTIVES This study aimed to identify current drug availability and prescribing practices in 12 sub-Saharan African countries and to examine(More)
BACKGROUND Despite the huge burden of HIV in sub-Saharan Africa, there is little evidence of the multidimensional needs of patients with HIV infection to inform the person-centred care across physical, psychological, social and spiritual domains stipulated in policy guidance. We aimed to describe the problems experienced by people with HIV in Kenya and(More)
Random amplified polymorphic DNA (RAPD) analysis was applied to individuals of Amphiura filiformis sampled from two geographic locations that have previously been reported to have different life history strategies. Of thirty-one 10-mer RAPD primers screened initially, four were chosen and used in a comparative analysis of A. filiformis individuals collected(More)