447 research outputs found

    Calculation of NMR Properties of Solitons in Superfluid 3He-A

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    Superfluid 3He-A has domain-wall-like structures, which are called solitons. We calculate numerically the structure of a splay soliton. We study the effect of solitons on the nuclear-magnetic-resonance spectrum by calculating the frequency shifts and the amplitudes of the soliton peaks for both longitudinal and transverse oscillations of magnetization. The effect of dissipation caused by normal-superfluid conversion and spin diffusion is calculated. The calculations are in good agreement with experiments, except a problem in the transverse resonance frequency of the splay soliton or in magnetic-field dependence of reduced resonance frequencies.Comment: 15 pages, 10 figures, updated to the published versio

    MeV-mass dark matter and primordial nucleosynthesis

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    The annihilation of new dark matter candidates with masses mXm_X in the MeV range may account for the galactic positrons that are required to explain the 511 keV Îł\gamma-ray flux from the galactic bulge. We study the impact of MeV-mass thermal relic particles on the primordial synthesis of 2^2H, 4^4He, and 7^7Li. If the new particles are in thermal equilibrium with neutrinos during the nucleosynthesis epoch they increase the helium mass fraction for m_X\alt 10 MeV and are thus disfavored. If they couple primarily to the electromagnetic plasma they can have the opposite effect of lowering both helium and deuterium. For mX=4m_X=4--10 MeV they can even improve the overall agreement between the predicted and observed 2^2H and 4^4He abundances.Comment: 11 pages, 10 figures, references and two appendices added, conclusions unchanged; accepted for publication in Phys.Rev.

    Coping with the effects of fear of failure in young elite athletes

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    Coping with stress is an important element in effective functioning at the elite level in sports, and fear of failure (FF) is an example of a stressor that athletes experience. Three issues underpin the present preliminary study. First, the prevalence of problems attributed to FF in achievement settings. Second, sport is a popular and significant achievement domain for children and adolescents. Third, there is a lack of research on FF in sport among this population. Therefore, the objectives of the study were to examine the effects of FF on young athletes and to find out their coping responses to the effects of FF. Interviews were conducted individually with nine young elite ath­letes (5 males, 4 females; ages 14-17 years). It was inferred from the data that FF affected the athletes' well-being, interpersonal behavior, sport performance, and schoolwork. The athletes employed a combination of problem-focused, emotion-fo­cused, and avoidance-focused coping strategies, with avoidance strategies being the most frequently reported

    The influence of DHA on language development: a review of randomized controlled trials of DHA supplementation in pregnancy, the neonatal period, and Infancy

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    This review summarizes randomized controlled trials (RCTs) assessing the effect of docosahexaenoic acid (DHA) supplementation in the first 1000 days on child language. Six databases were searched and RCTs were included if they involved supplementation with DHA during pregnancy, to preterm infants, or during the postpartum period, included a placebo group with less or no DHA, and reported a language outcome. We included 29 RCTs involving n = 10,405 participants from 49 publications. There was a total of 84 language measures at ages ranging from 3 months to 12 years. Of the 84 assessments, there were 4 instances where the DHA group had improved scores, and 2 instances where the DHA group had worse scores (with the majority of these significant effects found within one RCT). The remaining comparisons were null. A few RCTs that included subgroup analyses reported (inconsistent) effects. There was limited evidence that DHA supplementation had any effect on language development, although there were some rare instances of both possible positive and adverse effects, particularly within population subgroups. It is important that any subgroup effects are verified in future trials that are adequately powered to confirm such effects.Nicola R. Gawlik, Amanda J. Anderson, Maria Makrides, Lisa Kettler and Jacqueline F. Goul

    Probing the Environment with Galaxy Dynamics

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    I present various projects to study the halo dynamics of elliptical galaxies. This allows one to study the outer mass and orbital distributions of ellipticals in different environments, and the inner distributions of groups and clusters themselves.Comment: 5 pages, 2 figs, to appear in Proc. ESO Workshop, Groups of Galaxies in the Nearby Universe (5-9 Dec 2005), eds. I. Saviane, V. Ivanov & J. Borissova (Springer-Verlag

    Protocol for a multicentre prospective observational study of families with full-term infants on postnatal wards and in the community to capture feeding practices across the first year of life: the Mother Infant Lactation Questionnaire (MILQ) study

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    Introduction: Breastmilk is considered the gold standard for infant nutrition. Breast feeding is recommended as the sole source of nutrition between birth until around 6months of age and should be continued beyond this age as complementary foods are introduced. While breast feeding initiation is generally high in developed countries, continuation of breast feeding appears to drop rapidly. This is a prospective observational study of life that aims to characterise a current picture of infant feeding practices across the first year, and motivations for feeding practices, and to identify barriers and enablers for breast feeding. Methods and analysis: Caregivers with newborn singleton infants of normal birth weight are approached on the postnatal units of three hospitals in South Australia, or through targeted online advertising campaigns promoting the study. Caregivers are asked to complete surveys when their infant reaches 3, 5 and 7weeks’, and at 3, 4, 5, 6, 9 and 12 months of age. Initially, baseline characteristics, intentions and preferences for infant milk feeds, as well as reasons for preferences are captured. Latter surveys query how infants are being fed, difficulties or barriers to breast feeding, as well as any enablers (if breast feeding). Once infants reach 5months of age, surveys capture complementary feeding. A large opportunistic sample from the Adelaide community with a minimum of 1000 mother– infant pairs will be enrolled. The data will be analysed descriptively and using regression models. Ethics and dissemination: Women’s and Children’s Health Network Human Research Ethics Committee reviewed and approved the study (approval no HREC/19/ WCHN/140, approval date: 22 November 2019). Study results will be disseminated through academic meetings, peer-reviewed journals, in-services for postnatal healthcare services, results letters for participants and social media.Jacqueline F Gould, Lisa N Yelland, Robert A Gibson, Andrew J McPhee, Jojy Varghese, Rosalie Grivell, Maria Makride
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