717 research outputs found
Mammal predation by an ariid catfish in a dryland river of Western Australia
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
There are few more widely applied terms in common parlance than ācapabilityā. 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 Senās 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
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
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 nonātenure 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 ĻĪ³ for the Er c. m. =458 keV resonance in Ne 22 (p,Ī³) Na 23
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 ĻĪ³(458 keV) = 0.583(43) eV is more than 1Ļ 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
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 ĻĪ³=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
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 ā¼3 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
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
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 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 ĻĪ³pres(193keV)=(1.86Ā±0.13)Ć10-6 eV and ĻĪ³pres(518keV)=(13.70Ā±0.96)Ć10-3 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
Caffeine for apnea of prematurity and brain development at 11Ā years of age
Objective Caffeine therapy for apnea of prematurity has been reported to improve brain white matter microstructure at term-equivalent age, but its long-term effects are unknown. This study aimed to investigate whether caffeine affects (1) brain structure at 11 years of age, and (2) brain development from term-equivalent age to 11 years of age, compared with placebo. Methods Preterm infants born ā¤1250 g were randomly allocated to caffeine or placebo. Magnetic resonance imaging (MRI) was performed on 70 participants (33 caffeine, 37 placebo) at term-equivalent age and 117 participants (63 caffeine, 54 placebo) at 11 years of age. Global and regional brain volumes and white matter microstructure were measured at both time points. Results In general, there was little evidence for differences between treatment groups in brain volumes or white matter microstructure at age 11 years. There was, however, evidence that the caffeine group had a smaller corpus callosum than the placebo group. Volumetric brain development from term-equivalent to 11 years of age was generally similar between treatment groups. However, there was evidence that caffeine was associated with slower growth of the corpus callosum, and slower decreases in axial, radial, and mean diffusivities in the white matter, particularly at the level of the centrum semiovale, over time than placebo. Interpretation This study suggests any benefits of neonatal caffeine therapy on brain structure in preterm infants weaken over time and are not clearly detectable by MRI at age 11 years, although caffeine may have long-term effects on corpus callosum development.Claire E. Kelly, Wenn Lynn Ooi, Joseph Yuan-Mou Yang, Jian Chen, Chris Adamson, Katherine J. Lee ... et al
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