5,308 research outputs found

    A QTL for osteoporosis detected in an F2 population derived from White Leghorn chicken lines divergently selected for bone index

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    Osteoporosis, resulting from progressive loss of structural bone during the period of egg-laying in hens, is associated with an increased susceptibility to bone breakage. To study the genetic basis of bone strength, an F cross was produced from lines of hens that had been divergently selected for bone index from a commercial pedigreed White Leghorn population. Quantitative trait loci (QTL) affecting the bone index and component traits of the index (tibiotarsal and humeral strength and keel radiographic density) were mapped using phenotypic data from 372 F individuals in 32 F families. Genotypes for 136 microsatellite markers in 27 linkage groups covering ∌80% of the genome were analysed for association with phenotypes using within-family regression analyses. There was one significant QTL on chromosome 1 for bone index and the component traits of tibiotarsal and humeral breaking strength. Additive effects for tibiotarsal breaking strength represented 34% of the trait standard deviation and 7.6% of the phenotypic variance of the trait. These QTL for bone quality in poultry are directly relevant to commercial populations

    Cosmological gravitomagnetism and Mach's principle

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    The spin axes of gyroscopes experimentally define local non-rotating frames. But what physical cause governs the time-evolution of gyroscope axes? We consider linear perturbations of Friedmann-Robertson-Walker cosmologies with k=0. We ask: Will cosmological vorticity perturbations exactly drag the spin axes of gyroscopes relative to the directions of geodesics to quasars in the asymptotic unperturbed FRW space? Using Cartan's formalism with local orthonormal bases we cast the laws of linear cosmological gravitomagnetism into a form showing the close correspondence with the laws of ordinary magnetism. Our results, valid for any equation of state for cosmological matter, are: 1) The dragging of a gyroscope axis by rotational perturbations of matter beyond the Hubble-dot radius from the gyroscope is exponentially suppressed, where dot is the derivative with respect to cosmic time. 2) If the perturbation of matter is a homogeneous rotation inside some radius around a gyroscope, then exact dragging of the gyroscope axis by the rotational perturbation is reached exponentially fast as the rotation radius grows beyond the H-dot radius. 3) For the most general linear cosmological perturbations the time-evolution of all gyroscope spin axes exactly follow a weighted average of the energy currents of cosmological matter. The weight function is the same as in Ampere's law except that the inverse square law is replaced by the Yukawa force with the Hubble-dot cutoff. Our results demonstrate (in first order perturbation theory for FRW cosmologies with k = 0) the validity of Mach's hypothesis that axes of local non-rotating frames precisely follow an average of the motion of cosmic matter.Comment: 18 pages, 1 figure. Comments and references adde

    The practices of apartheid as a war crime: a critical analysis

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    The human suffering caused by the political ideology of apartheid in South Africa during the Apartheid era (1948-1994) prompted worldwide condemnation and a variety of diplomatic and legal responses. Amongst these responses was the attempt to have apartheid recognised both as a crime against humanity in the 1973 Apartheid Convention as well as a war crime in Article 85(4)(c) of Additional Protocol I. This article examines the origins, nature and current status of the practices of apartheid as a war crime and its possible application to the Israeli-Palestinian conflict

    Integument, mortality, and skeletal strength in extended production cycles for laying hens - effects of genotype and dietary zinc source

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    1. This study on long-life layers, covering the period 20-100 weeks of age, investigated longitudinal effects on mortality, layer integument, and skeletal properties in Bovans White (BoW) and Lohmann Selected Leghorn Classic (LSL), with or without supplementation with dietary organic zinc (Zn). 2. Two experiments, using 1440 layers in furnished small group cages (FC) and 1836 layers in a traditional floor housing system (Floor), were run in parallel. Each replicate consisted of five adjacent cages containing eight hens in each FC, or a pen with 102 layers in the Floor group. 3. Mortality was recorded daily. Integument and keel bone condition were scored at 35, 55, 85, and 100 weeks of age on 20% of the layers. Tibial strength was recorded from 933 layers at 100 weeks. Statistical analyses were performed on replicate means, with four to five and nine replicates per combination of hybrid and diet in Floor and FC groups, respectively. 4. Cumulative mortality was 9.6% and 16.3% in FC and Floor, respectively, and increased in the latter part of the production cycle, particularly in the Floor group. 5. In FC, LSL had inferior feather cover, less keel bone deviation, and shorter claws than BoW. In Floor, LSL had superior feather cover, less severe vent wounds, more bumble foot, and cleaner plumage than BoW. In both production systems, claws grew longer and keel bone deviation became more severe with age. 6. In FC, layers fed organic Zn had lower body weight and less keel bone deviation at 100 weeks of age. 7. In conclusion, keel bone integrity, claw length, and mortality rate are potential threats to welfare in long-life layers. Feather pecking is a problem that needs addressing at an early stage in the production period. On the whole, organic Zn did not improve welfare conditions in long-life layers

    We Walk: a person-centred, dyadic behaviour change intervention to promote physical activity through outdoor walking after stroke-an intervention development study.

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    From Europe PMC via Jisc Publications RouterHistory: ppub 2022-06-01, epub 2022-06-14Publication status: PublishedObjectivesTo develop We Walk, a theoretically informed, 12-week person-centred dyadic behaviour change intervention to increase physical activity (PA) in community-dwelling people with stroke (PWS) through outdoor walking.DesignThree-phase intervention development study. Phase 1: we reviewed literature on barriers and facilitators to PA after stroke and mapped them to the Behaviour Change Wheel and Theoretical Domains Framework to define intervention components. The Health Action Process Approach determined intervention structure underpinned by person-centred principles. Phase 2: stakeholder focus groups involving PWS, their companions and health professionals reviewed the draft intervention, and experts in behaviour change were consulted. Phase 3: informed by phases 1 and 2, the intervention and form of delivery were refined, with final review through patient and public involvement.SettingThree Scottish community rehabilitation stroke services.ParticipantsTwenty-three ambulatory community-dwelling PWS and their companions, thirty-seven health and exercise professionals, seven behaviour change experts.ResultsPhase 1 determined key intervention components: information about benefits of walking; developing motivation and confidence to walk; facilitating dyadic goal setting and making plans together; monitoring walking, overcoming challenges; and maintaining walking behaviour. Phase 2 review by stakeholder focus groups and behaviour change experts endorsed intervention components and structure, emphasising dyadic relational aspects as central to potential success. In phase 3, intervention content and handbooks for PWS and buddies were finalised. Healthcare professionals proposed third-sector delivery as most appropriate for intervention delivery. A detailed delivery manual was developed. Participants preferred facilitated face-to-face and telephone delivery.ConclusionsOur multilens intervention development approach ensured this novel intervention was evidence-informed, person-centred, theoretically coherent provided appropriate social support, and addressed issues of concern to PWS. This study established intervention components and structure and identified operational issues critical to future success. Future research will pilot and refine We Walk and evaluate acceptability, feasibility, effectiveness and cost-effectiveness.Trial registration numberISRCTN34488928

    Understanding Aesthetic Evaluation using Deep Learning

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    A bottleneck in any evolutionary art system is aesthetic evaluation. Many different methods have been proposed to automate the evaluation of aesthetics, including measures of symmetry, coherence, complexity, contrast and grouping. The interactive genetic algorithm (IGA) relies on human-in-the-loop, subjective evaluation of aesthetics, but limits possibilities for large search due to user fatigue and small population sizes. In this paper we look at how recent advances in deep learning can assist in automating personal aesthetic judgement. Using a leading artist's computer art dataset, we use dimensionality reduction methods to visualise both genotype and phenotype space in order to support the exploration of new territory in any generative system. Convolutional Neural Networks trained on the user's prior aesthetic evaluations are used to suggest new possibilities similar or between known high quality genotype-phenotype mappings

    In-service Initial Teacher Education in the Learning and Skills Sector in England: Integrating Course and Workplace Learning

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    The aim of the paper is to advance understanding of in-service learning and skills sector trainee teachers’ learning and propose ways of improving their learning. A conceptual framework is developed by extending Billett’s (International Journal of Educational Research 47:232–240, 2008) conceptualisation of workplace learning, as a relationally interdependent process between the opportunities workplaces afford for activities and interactions and how individuals engage with these, to a third base of participation, the affordances of the initial teacher education course. Hager and Hodkinson’s (British Educational Research Journal 35:619–638, 2009) metaphor of ‘learning as becoming’ is used to conceptualise the ways trainees reconstruct learning in a continuous transactional process of boundary crossing between course and workplace. The findings of six longitudinal case studies of trainees’ development, and evidence from other studies, illustrate the complex interrelationships between LSS workplace affordances, course affordances and trainee characteristics and the ways in which trainees reconstruct learning in each setting. The experience of teaching and interacting with learners, interactions with colleagues, and access to workplace resources and training are important workplace affordances for learning. However, some trainees have limited access to these affordances. Teaching observations, course activities and experiences as a learner are significant course affordances. Trainees’ beliefs, prior experiences and dispositions vary and significantly influence their engagement with course and workplace affordances. It is proposed that better integration of course and workplace learning through guided participation in an intentional workplace curriculum and attention to the ways trainees choose to engage with this, together with the use of practical theorising has the potential to improve trainee learning

    Influence of oxygen ordering kinetics on Raman and optical response in YBa_2Cu_3O_{6.4}

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    Kinetics of the optical and Raman response in YBa_2Cu_3O_{6.4} were studied during room temperature annealing following heat treatment. The superconducting T_c, dc resistivity, and low-energy optical conductivity recover slowly, implying a long relaxation time for the carrier density. Short relaxation times are observed for the B_{1g} Raman scattering -- magnetic, continuum, and phonon -- and the charge transfer band. Monte Carlo simulations suggest that these two relaxation rates are related to two length scales corresponding to local oxygen ordering (fast) and long chain and twin formation (slow).Comment: REVTeX, 3 pages + 4 PostScript (compressed) figure

    An investigation into the effects of solvent content on the image quality and stability of ink jet digital prints under varied storage conditions

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    Increasing numbers of galleries, museums and archives are including ink jet printed materials into their collections, and therefore displays. There is evidence that the instability of these prints is such that images can suffer deterioration in print quality or in extreme cases, a loss of information over an extended period of time. This is shorter than the period typically required for perceptible deterioration to occur in many other paper-based artworks. The image stability of prints is affected by a number of factors some of which have already been studied. However the role played by the ink solvent in the loss of image quality has yet to be explored. This paper will outline research being undertaken to investigate the effects of solvent content which may increase/promote the loss in image quality of the hard copy prints when stored or displayed under a range of temperature and humidity conditions

    Biocompatibility and application of carbon fibres in heart valve tissue engineering

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    The success of tissue engineered heart valves relies on a balance between polymer degradation, appropriate cell repopulation and ECM deposition, in order for the valves to continue their vital function. However, the process of remodelling is highly dynamic and species dependent. Carbon fibres have been well used in the construction industry for their high tensile strength and flexibility, and therefore might be relevant to support tissue engineered hearts valve during this transition in the mechanically demanding environment of the circulation. The aim of this study was to assess the suitability of carbon fibres to be incorporated into tissue engineered heart valves, with respect to optimising their cellular interaction and mechanical flexibility during valve opening and closure. The morphology and surface oxidation of the carbon fibres was characterised by scanning electron microscopy (SEM). Their ability to interact with human adipose derived stem cells (hADSCs) was assessed with respect to cell attachment and phenotypic changes. hADSCs attached and maintained their expression of stem cell markers with negligible differentiation to other lineages. Incorporation of carbon fibres into a stand-alone tissue engineered aortic root, comprised of jet-sprayed poly-caprolactone aligned fibres had no negative effects on the opening and closure characteristics of the valve when simulated in a pulsatile bioreactor. In conclusion, carbon fibres were found to be conducive to hADSC attachment and maintaining their phenotype. Carbon fibres were sufficiently flexible for full motion of valvular opening and closure. This study provides a proof of concept for the incorporation of carbon fibres into tissue engineered heart valves to continue their vital function during scaffold degradation
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