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Loss of fitness due to the accumulation of deleterious mutations appears to be inevitable in small, obligately asexual populations, as these are incapable of reconstituting highly fit genotypes by recombination or back mutation. The cumulative buildup of such mutations is expected to lead to an eventual reduction in population size, and this facilitates the(More)
In this study, computer simulation is used to show that despite synergistic epistasis for fitness, Muller's ratchet can lead to lethal fitness loss in a population of asexuals through the accumulation of deleterious mutations. This result contradicts previous work that indicated that epistasis will halt the ratchet. The present results show that epistasis(More)
DNA-dependent RNA polymerase I from E. coli has been used as probe for determining the capacity of purified chromatin isolated from inbred and hybrid rats during the course of postweaning development to serve as template for RNA synthesis in vitro. An analysis of variance reveals both strain- and age-specific differences in the incorporation of [3H]UTP into(More)
We report for the first time radiation data on a radiation-hardened high-precision resolver-to-digital converter (RDC). The RDC has a maximum of 16 bits precision, and is manufactured in a total-dose hardened 0.6 /spl mu/m CMOS process. Single-event (SEL) and dose-rate latchup hardening are designed-in using guard rings and DICE latches. Our results show(More)
UNLABELLED While the numbers of male nursing staff are growing in both the UK and the USA, there remains a significant imbalance both in terms of the total number and the specialities in which male staff choose to work. Management, education and technology-dominated roles, characterised as 'high-tech, low-touch' specialities attract disproportionately(More)
Diallel crosses among four highly inbred lines of rats were made in order to evaluate their combining ability at 10 day intervals during postnatal growth. Analyses were undertaken to consider the relative magnitudes of different components of variation, including a heterotic effect, over a long developmental period. A general analysis of variance for least(More)
1: a ‘systematic review’. Systematic reviews are a rigorous review of primary research on a particular topic. They are helpful to practitioners for gaining an overview of the best available evidence on a topic, and for making informed choices. Generally they are in a concise, reader-friendly format. This one is taken from a Cochrane Review. The six(More)