691 research outputs found

    Mammal predation by an ariid catfish in a dryland river of Western Australia

    Get PDF
    The presence of the spinifex hopping mouse Notomys alexis in the diet of lesser salmon catfish Neoarius graeffei from the Ashburton River, Western Australia, is reported for the first time. The consumption of terrestrial mammals by Australian freshwater fishes is widely considered to be an infrequent occurrence, of limited importance to aquatic food webs. However, remains of N. alexis were present within the stomachs of 44% of N. graeffei sampled, constituting approximately 95% of the total stomach contents. These findings suggest that N. graeffei will consume large quantities of terrestrial vertebrates when available, and may represent a valuable energy source for this ecologically important species in dryland river

    Sen and the art of educational maintenance: evidencing a capability, as opposed to an effectiveness, approach to schooling

    No full text
    There are few more widely applied terms in common parlance than ā€˜capabilityā€™. It is used (inaccurately) to represent everything from the aspiration to provide opportunity to notions of innate academic ability, with everything in between claiming apostolic succession to Amartya Sen, who (with apologies to Aristotle) first developed the concept. This paper attempts to warrant an adaptation of Senā€™s capability theory to schooling and schooling policy, and to proof his concepts in the new setting using research involving 100 pupils from 5 English secondary schools and a schedule of questions derived from the capability literature. The findings suggest that a capability approach can provide an alternative to the dominant Benthamite school effectiveness paradigm, and can offer a sound theoretical framework for understanding better the assumed relationship between schooling and well-being

    Long-term effects of lifetime trauma exposure in a rural community sample

    Get PDF
    Background This study examines the long-term outcomes of lifetime trauma exposure, including factors that contribute to the development of PTSD, in a sample of rural adults. Methods In 623 rural community residents, lifetime trauma exposure, PTSD, other psychiatric disorders and lifetime suicidal ideation were assessed using the World Mental Health Composite International Diagnostic Interview. Logistic regressions were used to examine relationships between potentially traumatic events (PTEs) and lifetime PTSD and other diagnoses. Results 78.2 % of participants reported at least on PTE. Rates were broadly comparable with Australian national data: the most commonly endorsed events were unexpected death of a loved one (43.7 %); witnessing injury or death (26.3 %); and life-threatening accident (19.3 %). While the mean age of the sample was 55 years, the mean age of first trauma exposure was 19 years. The estimated lifetime rate of PTSD was 16.0 %. Events with the strongest association with PTSD were physical assault and unexpected death of a loved one. Current functioning was lowest among those with current PTSD, with this group reporting elevated psychological distress, higher mental health service use, a greater number of comorbidities, and lower perceived social support. Respondents with a past PTE but no PTSD history were generally similar in terms of their current wellbeing to those with no lifetime PTE. Conclusions PTEs may have diverse psychological and social consequences beyond the development of PTSD. Ensuring that adequate support services are available in rural areas, particularly in the period immediately following a PTE, may reduce the long-term impact of traumatic events

    Application of assessment metrics for an academic department faculty development program

    Get PDF
    Faculty development is increasingly seen as a cornerstone of career sustainability in academic medicine, pediatrics, and other disciplines. Many current senior academic medical faculty developed their careers in systems that are distinctly different from current paradigms. Multiple internal and external variables have caused the academic environment to transform. These variables include rapidly changing technology, the opening of the academy to public scrutiny, external rankings, changes in the opportunities for academic advancement (including the increasing predominance of nonā€“tenure track faculty), sharp reductions in protected time for teaching, increased pressure to meet measurable benchmarks for academic and financial productivity, and an increased emphasis on multidisciplinary team science to more rapidly advance biomedical research. Faculty must also become adept at assessing learning outcomes, and engaging in collaborative projects that couple scholarly expertise with the local, national, or international communities. The increasing incidence of burnout and other sequelae of chronic stress among medical faculty is well documented and has led to recommendations for more formalized institutional attention to these threats to the academic medical enterprise

    New recommended Ļ‰Ī³ for the Er c. m. =458 keV resonance in Ne 22 (p,Ī³) Na 23

    Get PDF
    The Erc.m.=458 keV resonance in Ne22(p,Ī³)Na23 is an ideal reference resonance for measurements of cross sections and resonance strengths in noble gas targets. We report on a new measurement of the strength of this resonance. Data analysis employed the TFractionFitter class of root combined with geant simulations of potential decay cascades from this resonance. This approach allowed us to extract precise primary branching ratios for decays from the resonant state, including a new primary branch to the 7082-keV state in Na23. Our new resonance strength of Ļ‰Ī³(458 keV) = 0.583(43) eV is more than 1Ļƒ higher than a recent high-precision result that relied on literature branching ratios

    Measurement of the Er c. m. =259 keV resonance in the N 14 (p,Ī³) O 15 reaction MEASUREMENT of the Er c. m. =259 keV

    Get PDF
    The N14(p,Ī³)O15 reaction regulates the power generated by the CN cycle and thus impacts the structure and evolution of every star at some point in its life. The lowest positive-energy resonance in this reaction is located at Erc.m.=259 keV, too high in energy to strongly influence quiescent stellar burning. However, the strength of this resonance is used as a cross-section normalization for lower-energy measurements of this reaction. We report on new measurements of the energy, strength, and Ī³-ray branching ratios for the 259-keV resonance, using different detection and data-analysis schemes. We have also reevaluated previous results, where possible. Our new recommended strength of Ļ‰Ī³=12.6(3) meV is in agreement with the previous value of 13.1(6) meV, but is more precise and thus provides a more reliable normalization for low-energy (p,Ī³) measurements

    New measurements of low-energy resonances in the Ne 22 (p,Ī³) Na 23 reaction

    Get PDF
    The Ne22(p,Ī³)Na23 reaction is one of the most uncertain reactions in the NeNa cycle and plays a crucial role in the creation of Na23, the only stable Na isotope. Uncertainties in the low-energy rates of this and other reactions in the NeNa cycle lead to ambiguities in the nucleosynthesis predicted from models of thermally pulsing asymptotic giant branch (AGB) stars. This in turn complicates the interpretation of anomalous Na-O trends in globular cluster evolutionary scenarios. Previous studies of the Ne22(p,Ī³)Na23, Ne22(He3,d)Na23, and C12(C12,p)Na23 reactions disagree on the strengths, spins, and parities of low-energy resonances in Na23 and the direct-capture Ne22(p,Ī³)Na23 reaction rate contains large uncertainties as well. In this work we present new measurements of resonances at Erc.m.=417, 178, and 151 keV and of the direct-capture process in the Ne22(p,Ī³)Na23 reaction. The resulting total Ne22(p,Ī³)Na23 rate is approximately a factor of 20 higher than the rate listed in a recent compilation at temperatures relevant to hot-bottom burning in AGB stars. Although our rate is close to that derived from a recent Ne22(p,Ī³)Na23 measurement by Cavanna et al. in 2015, we find that this large rate increase results in only a modest 18% increase in the Na23 abundance predicted from a 5 M thermally pulsing AGB star model from Ventura and D'Antona (2005). The estimated astrophysical impact of this rate increase is in marked contrast to the factor of āˆ¼3 increase in Na23 abundance predicted by Cavanna et al. and is attributed to the interplay between the Na23(p,Ī±)Ne20 and Ne20(p,Ī³)Na21 reactions, both of which remain fairly uncertain at the relevant temperature range

    Universality in the Screening Cloud of Dislocations Surrounding a Disclination

    Full text link
    A detailed analytical and numerical analysis for the dislocation cloud surrounding a disclination is presented. The analytical results show that the combined system behaves as a single disclination with an effective fractional charge which can be computed from the properties of the grain boundaries forming the dislocation cloud. Expressions are also given when the crystal is subjected to an external two-dimensional pressure. The analytical results are generalized to a scaling form for the energy which up to core energies is given by the Young modulus of the crystal times a universal function. The accuracy of the universality hypothesis is numerically checked to high accuracy. The numerical approach, based on a generalization from previous work by S. Seung and D.R. Nelson ({\em Phys. Rev A 38:1005 (1988)}), is interesting on its own and allows to compute the energy for an {\em arbitrary} distribution of defects, on an {\em arbitrary geometry} with an arbitrary elastic {\em energy} with very minor additional computational effort. Some implications for recent experimental, computational and theoretical work are also discussed.Comment: 35 pages, 21 eps file

    High-intensity-beam study of O 17 (p,Ī³) F 18 and thermonuclear reaction rates for O 17 +p

    Get PDF
    Hydrogen burning of the oxygen isotopes takes place in low-mass stars, asymptotic giant branch stars, and classical novae. Observations of oxygen elemental and isotopic abundances in stellar spectra or in presolar grains provide strong constraints for stellar models if reliable thermonuclear reaction rates for hydrogen burning of oxygen are available. We present the results of a new measurement of the 17O(p,Ī³)18F reaction in the laboratory bombarding energy range of 170-530 keV. The measurement is performed with significantly higher beam intensities (Imax ā‰ˆ 2 mA) compared to previous work and by employing a sophisticated Ī³-ray coincidence spectrometer. We measured the cross section at much lower energies than previous in-beam experiments. We also apply a novel data-analysis technique that is based on the decomposition of different contributions to the measured pulse-height spectrum. Our measured strengths of the low-energy resonances amount to Ļ‰Ī³pres(193keV)=(1.86Ā±0.13)Ɨ10-6 eV and Ļ‰Ī³pres(518keV)=(13.70Ā±0.96)Ɨ10-3 eV. For the direct capture S factor at zero energy, we find a value of SDCpres(0) = 4.82Ā±0.41 keV b. We also present new thermonuclear rates for the 17O+p reactions, taking into account all consistent results from previous measurements

    Neural correlates of impaired vision in adolescents born extremely preterm and/or extremely low birthweight

    Get PDF
    BACKGROUND: Adolescents born extremely preterm (EP; <28 weeks' gestation) and/or extremely low birthweight (ELBW; <1000 g) experience high rates of visual impairments, however the potential neural correlates of visual impairments in EP/ELBW adolescents require further investigation. This study aimed to: 1) compare optic radiation and primary visual cortical structure between EP/ELBW adolescents and normal birthweight controls; 2) investigate associations between perinatal factors and optic radiation and primary visual cortical structure in EP/ELBW adolescents; 3) investigate associations between optic radiation and primary visual cortical structure in EP/ELBW adolescents and the odds of impaired vision. METHODS: 196 EP/ELBW adolescents and 143 controls underwent magnetic resonance imaging at a mean age of 18 years. Optic radiations were delineated using constrained spherical deconvolution based probabilistic tractography. Primary visual cortices were segmented using FreeSurfer software. Diffusion tensor variables and tract volume of the optic radiations, as well as volume, surface area and thickness of the primary visual cortices, were estimated. RESULTS: Axial, radial and mean diffusivities within the optic radiations, and primary visual cortical thickness, were higher in the EP/ELBW adolescents than controls. Within EP/ELBW adolescents, postnatal corticosteroid exposure was associated with altered optic radiation diffusion values and lower tract volume, while decreasing gestational age at birth was associated with increased primary visual cortical volume, area and thickness. Furthermore, decreasing optic radiation fractional anisotropy and tract volume, and increasing optic radiation diffusivity in EP/ELBW adolescents were associated with increased odds of impaired vision, whereas primary visual cortical measures were not associated with the odds of impaired vision. CONCLUSIONS: Optic radiation and primary visual cortical structure are altered in EP/ELBW adolescents compared with controls, with the greatest alterations seen in those exposed to postnatal corticosteroids and those born earliest. Structural alterations to the optic radiations may increase the risk of impaired vision in EP/ELBW adolescents.Claire E. Kelly, Jeanie L. Y. Cheong, Carly Molloy, Peter J. Anderson, Katherine J. Lee, Alice C. Burnet
    • ā€¦
    corecore