119 research outputs found
Associations between lamb survival and prion protein genotype: analysis of data for ten sheep breeds in Great Britain
BACKGROUND: Selective breeding programmes, based on prion protein (PrP) genotype, have been introduced throughout the European Union to reduce the risk of sheep transmissible spongiform encephalopathies (TSEs). These programmes could have negative consequences on other important traits, such as fitness and production traits, if the PrP gene has pleiotropic effects or is in linkage disequilibrium with genes affecting these traits. This paper presents the results of an investigation into associations between lamb survival and PrP genotype in ten mainstream sheep breeds in Great Britain (GB). In addition, the reasons for lamb deaths were examined in order to identify any associations between these and PrP genotype. RESULTS: Survival times from birth to weaning were analysed for over 38000 lambs (2427 dead and 36096 live lambs) from 128 flocks using Cox proportional hazard models for each breed, including additive animal genetic effects. No significant associations between PrP genotype and lamb survival were identified, except in the Charollais breed for which there was a higher risk of mortality in lambs of the ARR/VRQ genotype compared with those of the ARR/ARR genotype. Significant effects of birth weight, litter size, sex, age of dam and year of birth on survival were also identified. For all breeds the reasons for death changed significantly with age; however, no significant associations between reason for death and PrP genotype were found for any of the breeds. CONCLUSION: This study found no evidence to suggest that a selective breeding programme based on PrP genotype will have a detrimental effect on lamb survival. The only significant effect of PrP genotype identified was likely to be of little consequence because an increased risk of mortality was associated with a genotype that is selected against in current breeding strategies
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The strain-rate sensitivity of high-strength high-toughness steels.
The present study examines the strain-rate sensitivity of four high strength, high-toughness alloys at strain rates ranging from 0.0002 s-1 to 200 s-1: Aermet 100, a modified 4340, modified HP9-4-20, and a recently developed Eglin AFB steel alloy, ES-1c. A refined dynamic servohydraulic method was used to perform tensile tests over this entire range. Each of these alloys exhibit only modest strain-rate sensitivity. Specifically, the strain-rate sensitivity exponent m, is found to be in the range of 0.004-0.007 depending on the alloy. This corresponds to a {approx}10% increase in the yield strength over the 7-orders of magnitude change in strain-rate. Interestingly, while three of the alloys showed a concominant {approx}3-10% drop in their ductility with increasing strain-rate, the ES1-c alloy actually exhibited a 25% increase in ductility with increasing strain-rate. Fractography suggests the possibility that at higher strain-rates ES-1c evolves towards a more ductile dimple fracture mode associated with microvoid coalescence
Mobiliser et valoriser les donnĂ©es sur les sols forestiers. Compte rendu de lâatelier 4
Une meilleure connaissance des sols forestiers et lâamĂ©lioration des rĂ©fĂ©rentiels pour interprĂ©ter leur fonctionnement est une attente des forestiers comme des acteurs des politiques publiques. Lors de REGEFOR 2013, lâatelier âMobiliser et valoriser les donnĂ©es sur les sols forestiersâ a identifiĂ© une ressource importante et sous-exploitĂ©e de donnĂ©es au niveau des organismes de dĂ©veloppement et des laboratoires de recherche. Des outils existent pour les rendre plus visibles et accessibles sur le rĂ©seau internet. Face Ă la dispersion et Ă la faible harmonisation des jeux de donnĂ©es, des chantiers importants sont Ă mettre en oeuvre pour favoriser leur exploitation (exemple : mise en base de donnĂ©es, production de mĂ©tadonnĂ©es et de rĂ©fĂ©rentiels sĂ©mantiques communs, clarification des droits de propriĂ©tĂ©, protocoles dâĂ©changes de donnĂ©es entre applications). Dans cette optique, lâatelier a aussi conduit Ă sâinterroger sur les possibilitĂ©s dâamĂ©liorer la coordination entre production et gestion de donnĂ©es, notamment en discutant les intĂ©rĂȘts et limites dâune centralisation sous un mĂȘme systĂšme dâinformation
Modeling soil organic carbon dynamics in temperate forests with Yasso07
In a context of global changes, modeling and predicting the dynamics of soil carbon stocks (CSs) in forest ecosystems are vital but challenging. Yasso07 is considered to be one of the most promising models for such a purpose. We examine the accuracy of its prediction of soil carbon dynamics over the whole French metropolitan territory at a decennial timescale.
We used data from 101 sites in the RENECOFOR network, which encompasses most of the French temperate forests. These data include (i) the quantity of above-ground litterfall from 1994 to 2008, measured yearly, and (ii) the soil CSs measured twice at an interval of approximately 15 years (once in the early 1990s and around 2010). We used Yasso07 to simulate the annual changes in carbon stocks (ACCs; in tCâhaâ1âyrâ1) for each site and then compared the estimates with actual recorded data. We carried out meta-analyses to reveal the variability in litter biochemistry in different tree organs for conifers and broadleaves. We also performed sensitivity analyses to explore Yasso07's sensitivity to annual litter inputs and model initialization settings.
At the national level, the simulated ACCs (+0.00±0.07âtCâhaâ1âyrâ1, meanâ±âSE) were of the same order of magnitude as the observed ones (+0.34±0.06âtCâhaâ1âyrâ1). However, the correlation between predicted and measured ACCs remained weak (R2<0.1). There was significant overestimation for broadleaved stands and underestimation for coniferous sites. Sensitivity analyses showed that the final estimated CS was strongly affected by settings in the model initialization, including litter and soil carbon quantity and quality and also by simulation length. Carbon quality set with the partial steady-state assumption gave a better fit than the model with the complete steady-state assumption.
With Yasso07 as the support model, we showed that there is currently a bottleneck in soil carbon modeling and prediction due to a lack of knowledge or data on soil carbon quality and fine-root quantity in the litter
For public (and recontextualized) sociology: The promises and perils of public engagement in an age of mediated communication
This article argues for the analysis of public engagement as an essentially mediated activity. Although recent studies note that academic knowledge is increasingly available for consumption by nonacademic audiences, they tell us little about how it gets recontextualized while passing through the hands of media professionals on its way toward such audiences. In Burawoyâs (2005) influential call for the rebirth of public sociology, as in the debates his work provoked, the media is treated solely as a means for the transportation of knowledge. But as this article demonstrates, the media does not simply transport knowledge; it also, and at the same time, translates that knowledge in various, rhetorically
consequential ways. Focusing on the mediated trajectory of an attempt by a group of academics to connect with audiences beyond academia, their initial contribution is compared to its subsequent translation(s) across various British newspapers. A discursive analysis reveals the techniques via which a classic form of public sociology came to be recontextualized such that, remarkably, these authors were left appearing to voice nothing but their own petty prejudices. The article concludes by noting
that where public engagement involves mediation, public sociology should pay more attention to the recontextualizing affordances of media discourse
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