14,751 research outputs found

    The Quantum McKay Correspondence for polyhedral singularities

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    Let G be a polyhedral group, namely a finite subgroup of SO(3). Nakamura's G-Hilbert scheme provides a preferred Calabi-Yau resolution Y of the polyhedral singularity C^3/G. The classical McKay correspondence describes the classical geometry of Y in terms of the representation theory of G. In this paper we describe the quantum geometry of Y in terms of R, an ADE root system associated to G. Namely, we give an explicit formula for the Gromov-Witten partition function of Y as a product over the positive roots of R. In terms of counts of BPS states (Gopakumar-Vafa invariants), our result can be stated as a correspondence: each positive root of R corresponds to one half of a genus zero BPS state. As an application, we use the crepant resolution conjecture to provide a full prediction for the orbifold Gromov-Witten invariants of [C^3/G].Comment: Introduction rewritten. Issue regarding non-uniqueness of conifold resolution clarified. Version to appear in Inventione

    Non-equilibrium dynamic critical scaling of the quantum Ising chain

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    We solve for the time-dependent finite-size scaling functions of the 1D transverse-field Ising chain during a linear-in-time ramp of the field through the quantum critical point. We then simulate Mott-insulating bosons in a tilted potential, an experimentally-studied system in the same equilibrium universality class, and demonstrate that universality holds for the dynamics as well. We find qualitatively athermal features of the scaling functions, such as negative spin correlations, and show that they should be robustly observable within present cold atom experiments.Comment: 4 pages + 2 page supplemen

    Progression from ocular hypertension to visual field loss in the English hospital eye service

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    Background There are more than one million National Health Service visits in England and Wales each year for patients with glaucoma or ocular hypertension (OHT). With the ageing population and an increase in optometric testing, the economic burden of glaucoma-related visits is predicted to increase. We examined the conversion rates of OHT to primary open-angle glaucoma (POAG) in England and assessed factors associated with risk of conversion. Methods Electronic medical records of 45 309 patients from five regionally different glaucoma clinics in England were retrospectively examined. Conversion to POAG from OHT was defined by deterioration in visual field (two consecutive tests classified as stage 1 or worse as per the glaucoma staging system 2). Cox proportional hazards models were used to examine factors (age, sex, treatment status and baseline intraocular pressure (IOP)) associated with conversion. Results The cumulative risk of conversion to POAG was 17.5% (95% CI 15.4% to 19.6%) at 5 years. Older age (HR 1.35 per decade, 95% CI 1.22 to 1.50, p<0.001) was associated with a higher risk of conversion. IOP-lowering therapy (HR 0.45, 95% CI 0.35 to 0.57, p<0.001) was associated with a lower risk of conversion. Predicted 5-year conversion rates for treated and untreated groups were 14.0% and 26.9%, respectively. Conclusion Less than one-fifth of OHT patients managed in glaucoma clinics in the UK converted to POAG over a 5-year period, suggesting many patients may require less intensive follow-up. Our study provides real-world evidence for the efficacy of current management (including IOP-lowering treatment) at reducing risk of conversion

    Impact of Changes in U.S. Grain Standards on Discounts for Insects in Stored Grain

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    The Federal Grain Inspection Service changed U.S. grain standards in 1988. Insect discounts given at country elevators and at terminal elevators were analyzed to determine impacts of the new standards. Insect discounts influence grain quality by affecting insect control decisions by producers and country elevator managers.Grain Inspection, Insect Discounts, Wheat, Farm Storage, Elevator Storage, Crop Production/Industries,

    Targets and self monitoring in hypertension: randomised controlled trial and cost effectiveness analysis

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    Objectives: To assess whether blood pressure control in primary care could be improved with the use of patient held targets and self monitoring in a practice setting, and to assess the impact of these on health behaviours, anxiety, prescribed antihypertensive drugs, patients’ preferences, and costs. \ud Design: Randomised controlled trial. \ud Setting: Eight general practices in south Birmingham. \ud Participants: 441 people receiving treatment in primary care for hypertension but not controlled below the target of < 140/85 mm Hg. \ud Interventions: Patients in the intervention group received treatment targets along with facilities to measure their own blood pressure at their general practice; they were also asked to visit their general practitioner or practice nurse if their blood pressure was repeatedly above the target level. Patients in the control group received usual care (blood pressure monitoring by their practice). \ud Main outcome measures: Primary outcome: change in systolic blood pressure at six months and one year in both intervention and control groups. Secondary outcomes: change in health behaviours, anxiety, prescribed antihypertensive drugs, patients’ preferences of method of blood pressure monitoring, and costs. \ud Results: 400 (91%) patients attended follow up at one year. Systolic blood pressure in the intervention group had significantly reduced after six months (mean difference 4.3 mm Hg (95% confidence interval 0.8 mm Hg to 7.9 mm Hg)) but not after one year (mean difference 2.7 mm Hg (-1.2 mm Hg to 6.6 mm Hg)). No overall difference was found in diastolic blood pressure, anxiety, health behaviours, or number of prescribed drugs. Patients who self monitored lost more weight than controls (as evidenced by a drop in body mass index), rated self monitoring above monitoring by a doctor or nurse, and consulted less often. Overall, self monitoring did not cost significantly more than usual care (£251 ($437; 364 euros) (95% confidence interval £233 to £275) versus £240 (£217 to £263). \ud Conclusions: Practice based self monitoring resulted in small but significant improvements of blood pressure at six months, which were not sustained after a year. Self monitoring was well received by patients, anxiety did not increase, and there was no appreciable additional cost. Practice based self monitoring is feasible and results in blood pressure control that is similar to that in usual care. \u

    Managing sleep and wakefulness in a 24 hour world

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    This article contributes to literature on the sociology of sleep by exploring the sleeping practices and subjective sleep experiences of two social groups: shift workers and students. It draws on data, collected in the UK from 25 semi-structured interviews, to discuss the complex ways in which working patterns and social activities impact upon experiences and expectations of sleep in our wired awake world. The data show that, typically, sleep is valued and considered to be important for health, general wellbeing, appearance and physical and cognitive functioning. However, sleep time is often cut back on in favour of work demands and social activities. While shift workers described their efforts to fit in an adequate amount of sleep per 24-hour period, for students, the adoption of a flexible sleep routine was thought to be favourable for maintaining a work–social life balance. Collectively, respondents reported using a wide range of strategies, techniques, technologies and practices to encourage, overcome or delay sleep(iness) and boost, promote or enhance wakefulness/alertness at socially desirable times. The analysis demonstrates how social context impacts not only on how we come to think about sleep and understand it, but also how we manage or self-regulate our sleeping patterns

    Blood Glucose Levels and High Intensity Exercise with Respect to Meal Timing

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    The research conducted was about monitoring blood glucose levels with exercise with respect to meal timing. It has been hypothesized that with short bouts of high intensity exercise, one can raise their blood glucose levels because in acute response to high intensity exercise. Previous research has shown that with long bouts of exercise while fasting you can lower blood glucose levels. This study is testing the meal timing from fasting to right before the exercise and also eating one and two hours before combined with a 50 minute moderate to high intensity workout, keeping the heart rate in zones 3- 5, which is around 70%-100% Of their VO2 Max, which was tested by using An H7 sensor. The research population ranged from male to female, and ages from 19-39 year old college students. The test is administered before the workout and after the workout. There is hope that with enough data we can support that an individual can increase glycogen levels when eating at the perfect time for increased muscle capacity, but also how you can lower blood glucose levels with different types of exercise when fasting. This info will be very beneficial to people who suffer from diabetes, or even athletes who was to optimize performance

    Unusual Phase Transitions and Magnetoelastic Coupling in TlFe1.6Se2 Single Crystals

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    Structural, magnetic, electrical transport, and heat capacity data are reported for single crystals of TlFe1.6Se2. This compound crystallizes in a tetragonal structure similar to the ThCr2Si2 structure, but with vacancies in the Fe layer. The vacancies can be ordered or disordered depending on temperature and thermal history. If the vacancies are ordered, the basal plane lattice constant increases from a to \sqrt{5}a. Antiferromagnetic order with the Fe spins along the c-axis occurs below T_N ~ 430K as shown by single crystal neutron diffraction and the magnetic structure is reported. In addition, for the vacancy ordered crystal, two other phase transitions are found at T_1 ~ 140K, and T_2 ~ 100K. The phase transitions at T_1 and T_2 are evident in heat capacity, magnetic susceptibility, resistivity data, a and c lattice parameters, and in the unusual temperature dependence of the magnetic order parameter determined from neutron scattering. The phase transitions at T_1 and T_2 result in significant changes in the magnetic moment per iron, with 1.72(6)\mu_B observed at 300K, 2.07(9)\mu_B at 140\,K, 1.90(9)\,\mu_B at 115\,K, and 1.31(8)\mu_B for 5\,K if the same "block checkerboard" magnetic structure is used at all temperatures. The phase transitions appear to be driven by small changes in the c lattice constant, large magnetoelastic coupling, and the localization of carriers with decreasing temperature.Comment: Accepted for publication in Physical Review

    In vivo nuclear magnetic resonance imaging

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    A number of physiological changes have been demonstrated in bone, muscle and blood after exposure of humans and animals to microgravity. Determining mechanisms and the development of effective countermeasures for long duration space missions is an important NASA goal. The advent of tomographic nuclear magnetic resonance imaging (NMR or MRI) gives NASA a way to greatly extend early studies of this phenomena in ways not previously possible; NMR is also noninvasive and safe. NMR provides both superb anatomical images for volume assessments of individual organs and quantification of chemical/physical changes induced in the examined tissues. The feasibility of NMR as a tool for human physiological research as it is affected by microgravity is demonstrated. The animal studies employed the rear limb suspended rat as a model of mucle atrophy that results from microgravity. And bedrest of normal male subjects was used to simulate the effects of microgravity on bone and muscle
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