52 research outputs found

    Chronos: A NIR spectroscopic galaxy survey to probe the most fundamental stages of galaxy evolution

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    We propose a dedicated, ultra-deep spectroscopic survey in the near infrared (NIR), that will target a mass-limited sample of galaxies during two of the most fundamental epochs of cosmic evolution: the formation of the first galaxies (at z ≳ 6; comsmic dawn), and at the peak of galaxy formation activity (at redshift z∼1–3; cosmic noon). By way of NIR observations (λ= 0.8–2μ m), it is possible to study the UV Lyman-α region in the former, and the optical rest-frame in the latter, allowing us to extract fundamental observables such as gas and stellar kinematics, chemical abundances, and ages, providing a unique legacy database covering these two crucial stages of cosmic evolution. The need to work in the NIR at extremely low flux levels makes a ground-based approach unfeasible due to atmospheric emission and absorption. Only with the largest facilities of the future (e.g. ELT) will be possible to observe a reduced set of targets, comprising at most of order thousands of galaxies. Likewise, from space, the small field of view of JWST and its use as a general purpose facility will yield a rather small set of high quality NIR spectra of distant galaxies (in the thousands, at best). Our project (codename Chronos) aims to produce ∼1 million high quality spectra, with a high S/N in the continuum, where information about the underlying stellar populations is encoded. The main science drivers are: - The connection between the star formation history and the mass assembly history. - The role of AGN and supernova feedback in shaping the formation histories of galaxies, with a quantitative estimate of quenching timescales. - The formation of the first galaxies. - The source of reionization. - Evolution of the metallicity-mass relation, including [α/Fe] and individual abundances. - Precision cosmology through detailed studies of the “baryon physics” of galaxy formation, probing the power spectrum over scales k∼1 Mpc− 1

    Vitamin D supplementation for the prevention of type 2 diabetes in overweight adults: study protocol for a randomized controlled trial

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    Despite Australia's sunny climate, low vitamin D levels are increasingly prevalent. Sun exposure is limited by long working hours, an increase in time spent indoors, and sun protection practices, and there is limited dietary vitamin D fortification. While the importance of vitamin D for bone mineralization is well known, its role as a protective agent against chronic diseases, such as type 2 diabetes and cardiovascular disease, is less understood. Observational and limited intervention studies suggest that vitamin D might improve insulin sensitivity and secretion, mainly via its anti-inflammatory properties, thereby decreasing the risk of development and progression of type 2 diabetes. The primary aim of this trial is to investigate whether improved plasma concentrations of 25-hydroxyvitamin D (25(OH)D), obtained through vitamin D supplementation, will increase insulin sensitivity and insulin secretion. A secondary aim is to determine whether these relationships are mediated by a reduction in underlying subclinical inflammation associated with obesity.Fifty overweight but otherwise healthy nondiabetic adults between 18 and 60 years old, with low vitamin D levels (25(OH)D < 50 nmol/l), will be randomly assigned to intervention or placebo. At baseline, participants will undergo a medical review and anthropometric measurements, including dual X-ray absorptiometry, an intravenous glucose tolerance test, muscle and fat biopsies, a hyperinsulinemic euglycemic clamp, and questionnaires assessing diet, physical activity, sun exposure, back and knee pain, and depression. The intervention group will receive a first dose of 100,000 IU followed by 4,000 IU vitamin D (cholecalciferol) daily, while the placebo group will receive apparently identical capsules, both for a period of 16 weeks. All measurements will be repeated at follow-up, with the primary outcome measure expressed as a change from baseline in insulin sensitivity and secretion for the intervention group compared with the placebo group. Secondary outcome measures will compare changes in anthropometry, cardiovascular risk factors, and inflammatory markers.The trial will provide much needed clinical evidence on the impact of vitamin D supplementation on insulin resistance and secretion and its underlying mechanisms, which are relevant for the prevention and management of type 2 diabetes.Clinicaltrials.gov ID: NCT02112721 .Barbora de Courten, Aya Mousa, Negar Naderpoor, Helena Teede, Maximilian P J de Courten and Robert Scrag

    Effectiveness of student response systems in terms of learning environment, attitudes and achievement

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    In order to investigate the effectiveness of using Student Response Systems (SRS) among grade 7 and 8 science students in New York, the How Do You Feel About This Class? (HDYFATC) questionnaire was administered to 1097 students (532 students did use SRS and 565 students who did not use SRS). Data analyses attested to the sound factorial validity and internal consistency reliability of the HDYFATC, as well as its ability to differentiate between the perceptions of students in different classrooms. Very large differences between users and non-users of SRS, ranging from 1.17 to 2.45 standard deviations for various learning environment scales, attitudes and achievement, supported the efficacy of using SRS

    The impact of statins on health services utilization and mortality in older adults discharged from hospital with ischemic heart disease: a cohort study

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    <p>Abstract</p> <p>Background</p> <p>Cardiovascular disease (CVD) carries a high burden of morbidity and mortality and is associated with significant utilization of health care resources, especially in the elderly. Numerous randomized trials have established the efficacy of cholesterol reduction with statin medications in decreasing mortality in high-risk populations. However, it is not known what the effect of the utilization of these medications in complex older adults has had on mortality and on the utilization of health services, such as physician visits, hospitalizations or cardiovascular procedures.</p> <p>Methods</p> <p>This project linked clinical and hospital data from the Improving Cardiovascular Outcomes in Nova Scotia (ICONS) database with administrative data from the Population Health Research Unit to identify all older adults hospitalized with ischemic heart disease between October 15, 1997 and March 31, 2001. All patients were followed for at least one year or until death. Multiple regression techniques, including Cox proportional hazards models and generalized linear models were employed to compare health services utilization and mortality for statin users and non-statin users.</p> <p>Results</p> <p>Of 4232 older adults discharged alive from the hospital, 1629 (38%) received a statin after discharge. In multivariate models after adjustment for demographic and clinical characteristics, and propensity score, statins were associated with a 26% reduction in all- cause mortality (hazard ratio (HR) 0.74, 95% confidence interval (CI) 0.63-0.88). However, statin use was not associated with subsequent reductions in health service utilization, including re-hospitalizations (HR, 0.98, 95% CI 0.91-1.06), physician visits (relative risk (RR) 0.97, 95% CI 0.92-1.02) or coronary revascularization procedures (HR 1.15, 95% CI 0.97-1.36).</p> <p>Conclusion</p> <p>As the utilization of statins continues to grow, their impact on the health care system will continue to be important. Future studies are needed to continue to ensure that those who would realize significant benefit from the medication receive it.</p

    A Social Identity Approach to Sport Psychology: Principles, Practice, and Prospects.

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    Drawing on social identity theory and self-categorization theory, we outline an approach to sport psychology that understands groups not simply as features of sporting contexts but rather as elements that can be, and often are, incorporated into a person's sense of self and, through this, become powerful determinants of their sport-related behavior. The underpinnings of this social identity approach are outlined, and four key lessons for sport that are indicative of the analytical and practical power of the approach are presented. These suggest that social identity is the basis for sports group (1) behavior, (2) formation and development, (3) support and stress appraisal, and (4) leadership. Building on recent developments within sport science, we outline an agenda for future research by identifying a range of topics to which the social identity approach could fruitfully contribute

    Dynamic Tunneling of Ultra-Cold Atoms

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    The divergence of quantum and classical descriptions of particle motion is clearly apparent in quantum tunnelling1, 2 between two regions of classically stable motion. An archetype of such non-classical motion is tunnelling through an energy barrier. In the 1980s, a new process, 'dynamical' tunnelling1, 2, 3, was predicted, involving no potential energy barrier; however, a constant of the motion (other than energy) still forbids classically the quantum-allowed motion. This process should occur, for example, in periodically driven, nonlinear hamiltonian systems with one degree of freedom4, 5, 6. Such systems may be chaotic, consisting of regions in phase space of stable, regular motion embedded in a sea of chaos. Previous studies predicted4 dynamical tunnelling between these stable regions. Here we observe dynamical tunnelling of ultracold atoms from a Bose-Einstein condensate in an amplitude-modulated optical standing wave. Atoms coherently tunnel back and forth between their initial state of oscillatory motion (corresponding to an island of regular motion) and the state oscillating 180° out of phase with the initial state
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