932 resultados para Horses - Reproduction
Resumo:
The research uses a sociological perspective to build an improved, context specific understanding of innovation diffusion within the UK construction industry. It is argued there is an iterative interplay between actors and the social system they occupy that directly influences the diffusion process as well as the methodology adopted. The research builds upon previous findings that argued a level of best fit for the three innovation diffusion concepts of cohesion, structural equivalence and thresholds. That level of best fit is analysed here using empirical data from the UK construction industry. This analysis allows an understanding of how the relative importance of these concepts' actually varies within the stages of the innovation diffusion process. The conclusion that the level of relevance fluctuates in relation to the stages of the diffusion process is a new development in the field.
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Finding an estimate of the channel impulse response (CIR) by correlating a received known (training) sequence with the sent training sequence is commonplace. Where required, it is also common to truncate the longer correlation to a sub-set of correlation coefficients by finding the set of N sequential correlation coefficients with the maximum power. This paper presents a new approach to selecting the optimal set of N CIR coefficients from the correlation rather than relying on power. The algorithm reconstructs a set of predicted symbols using the training sequence and various sub-sets of the correlation to find the sub-set that results in the minimum mean squared error between the actual received symbols and the reconstructed symbols. The application of the algorithm is presented in the context of the TDMA based GSM/GPRS system to demonstrate an improvement in the system performance with the new algorithm and the results are presented in the paper. However, the application lends itself to any training sequence based communication system often found within wireless consumer electronic device(1).
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Recognising the growing significance of sport and recreation in the countryside, this paper seeks to examine the changing demand for, and supply of, opportunities for horse riding in the countryside. It considers the physical problems associated with horse riding, together with the changing social context. The paper considers possible solutions to the issues raised, both within existing rights of way legislation and via new opportunities created by the revisions to agricultural support that have occurred in the last decade. The paper concludes that while the new opportunities have ameliorated some of the problems associated with the supply of land for horse riding, no new rights of access have been conferred. The ability of horse riders to guarantee continued provision will be governed partially by the market but also by future agricultural support policy.
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Theoretical and empirical studies of life history aim to account for resource allocation to the different components of fitness: survival, growth, and reproduction. The pioneering evolutionary ecologist David Lack [(1968) Ecological Adaptations for Breeding in Birds (Methuen and Co.,London)] suggested that reproductive output in birds reflects adaptation to environmental factors such as availability of food and risk of predation, but subsequent studies have not always supported Lack’s interpretation. Here using a dataset for 980 bird species (Dataset S1), a phylogeny, and an explicit measure of reproductive productivity, we test predictions for how mass-specific productivity varies with body size, phylogeny,and lifestyle traits. We find that productivity varies negatively with body size and energetic demands of parental care and positively with extrinsic mortality. Specifically: (i) altricial species are 50% less productive than precocial species; (ii) species with female-only care of offspring are about 20% less productive than species with other methods of parental care; (iii) nonmigrants are 14% less productive than migrants; (iv) frugivores and nectarivores are about 20% less productive than those eating other foods; and (v) pelagic foragers are 40% less productive than those feeding in other habitats. A strong signal of phylogeny suggests that syndromes of similar life-history traits tend to be conservative within clades but also to have evolved independently in different clades. Our results generally support both Lack’s pioneering studies and subsequent research on avian life history.
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Three strains of a Gram-positive, catalase-positive, fermentative, non-lipophilic, previously unknown bacterium were isolated from urogenital samples taken from mares in Scotland (M401624/00/1) and Sweden (VM 2074 and VM 2298T). All were deposited with the CCUG with tentative identifications as Corynebacterium spp. The strains were characterized using a polyphasic taxonomic approach. Biochemically, the strains were very similar to each other, but phylogenetically distinct from Corynebacterium species with validly published names (≤95% sequence similarity). rpoB gene sequence data confirmed the strains belonged to the same species (>99% sequence similarity) and were distinct from species with validly published names (>13% sequence divergence). On the basis of phenotypic and sequence data, the strains represent a novel species within the genus Corynebacterium, for which the name Corynebacterium uterequi is proposed. The type strain is VM 2298T (=CCUG 61235T = DSM 45634T), isolated from equine uterus.
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1. Bees are one of the most important groups of pollinators in the temperate zone. Although heavy metal pollution is recognised to be a problem affecting large parts of the European Union, we currently lack insights into the effects of heavy metals on wild bee survival and reproduction. 2. We investigated the impact of heavy metal pollution on the wild bee Osmia rufa (Hymenoptera: Megachilidae) by comparing their survival, reproduction and population dynamics along two independent gradients of heavy metal pollution, one in Poland and the other in the United Kingdom. We used trap nests to evaluate the response of fitness and survival parameters of O. rufa. To quantify the levels of pollution, we directly measured the heavy metal concentration in provisions collected by O. rufa. 3. We found that with increasing heavy metal concentration, there was a steady decrease in number of brood cells constructed by females and an increase in the proportion of dead offspring. In the most polluted site, there were typically 3–4 cells per female with 50–60% dead offspring, whereas in unpolluted sites there were 8 to 10 cells per female and only 10–30% dead offspring. Moreover, the bee population growth rate (R0) decreased along the heavy metal pollution gradients. In unpolluted sites, R0 was above 1, whereas in contaminated sites, the values tended to be below 1. 4. Our findings reveal a negative relationship between heavy metal pollution and several fitness parameters of the wild bee O. rufa, and highlight a mechanism whereby the detrimental effects of heavy metal pollution may severely impact wild bee communities.
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This paper presents direct radiocarbon measurements on horse skeletal remains from the Beaker period settlement at the site of Newgrange in Ireland, finds which have previously been argued as the earliest domestic horses in Ireland. The new determinations date the horse remains to the Irish Iron Age and shed important new light on the introduction of domestic horses to Ireland and to north-west Europe more generally. Although the new dates undermine the idea for the introduction of horses as part of a ‘Beaker package’, the early use of horse is not well defined archaeologically or chronologically and the earliest use of domestic horses in Ireland and Britain is still uncertain. This paper also identifies evidence for heavy bitting damage on the Iron Age Newgrange horse teeth and presents some possible parallels between the evidence from Newgrange and that at Tara, which has been previously linked with kingship rituals
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There is a period of some 5000 years or so in the prehistory of Europe when horse populations were greatly depleted and perhaps even disappeared in many places. Before this time, during the Upper Palaeolithic, wild horses were common; after, during the Bronze Age, domestic horses were being raised and used across Europe. What happened in between is uncertain, in part because of the sketchy archaeological record. Debates continue as to the origins (the when, where and how) of Europe's domestic horses, including whether horse husbandry dispersed only from habitats favourable to horses on the Eurasian steppes or whether there was local domestication in temperate Europe. This paper reviews the evidence for the transition from wild horses to domestic horses in Europe.
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As studies uncover the breadth of microbes associated with human life, opportunities will emerge to manipulate and augment their functions in ways that improve health and longevity. From involvement in the complexities of reproduction and fetal/infant development, to delaying the onset of disease, and indeed countering many maladies, microbes offer hope for human well-being. Evidence is emerging to suggest that microbes may play a beneficial role in body sites traditionally viewed as being sterile. Although further evidence is required, we propose that much of medical dogma is about to change significantly through recognition and understanding of these hitherto unrecognized microbe–host interactions. A meeting of the International Scientific Association for Probiotics and Prebiotics held in Aberdeen, Scotland (June 2014), presented new views and challenged established concepts on the role of microbes in reproduction and health of the mother and infant. This article summarizes some of the main aspects of these discussions.
Resumo:
Influences of inbreeding on daily milk yield (DMY), age at first calving (AFC), and calving intervals (CI) were determined on a highly inbred zebu dairy subpopulation of the Guzerat breed. Variance components were estimated using animal models in single-trait analyses. Two approaches were employed to estimate inbreeding depression: using individual increase in inbreeding coefficients or using inbreeding coefficients as possible covariates included in the statistical models. The pedigree file included 9,915 animals, of which 9,055 were inbred, with an average inbreeding coefficient of 15.2%. The maximum inbreeding coefficient observed was 49.45%, and the average inbreeding for the females still in the herd during the analysis was 26.42%. Heritability estimates were 0.27 for DMY and 0.38 for AFC. The genetic variance ratio estimated with the random regression model for CI ranged around 0.10. Increased inbreeding caused poorer performance in DMY, AFC, and CI. However, some of the cows with the highest milk yield were among the highly inbred animals in this subpopulation. Individual increase in inbreeding used as a covariate in the statistical models accounted for inbreeding depression while avoiding overestimation that may result when fitting inbreeding coefficients.