3,143 research outputs found

    The Omega Deformation, Branes, Integrability, and Liouville Theory

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    We reformulate the Omega-deformation of four-dimensional gauge theory in a way that is valid away from fixed points of the associated group action. We use this reformulation together with the theory of coisotropic A-branes to explain recent results linking the Omega-deformation to integrable Hamiltonian systems in one direction and Liouville theory of two-dimensional conformal field theory in another direction.Comment: 96 p

    Prostacyclins have no direct inotropic effect on isolated atrial strips from the normal and pressure-overloaded human right heart

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    Prostacyclins are vasodilatory agents used in the treatment of pulmonary arterial hypertension. The direct effects of prostacyclins on right heart function are still not clarified. The aim of this study was to investigate the possible direct inotropic properties of clinical available prostacyclin mimetics in the normal and the pressure-overloaded human right atrium. Trabeculae from the right atrium were collected during surgery from chronic thromboembolic pulmonary hypertension (CTEPH) patients with pressure-overloaded right hearts, undergoing pulmonary thromboendarterectomy (n = 10) and from patients with normal right hearts operated by valve replacement or coronary bypass surgery (n = 9). The trabeculae were placed in an organ bath, continuously paced at 1 Hz. They were subjected to increasing concentrations of iloprost, treprostinil, epoprostenol, or MRE-269, followed by isoprenaline to elicit a reference inotropic response. The force of contraction was measured continuously. The expression of prostanoid receptors was explored through quantitative polymerase chain reaction (qPCR). Iloprost, treprostinil, epoprostenol, or MRE-269 did not alter force of contraction in any of the trabeculae. Isoprenaline showed a direct inotropic response in both trabeculae from the pressure-overloaded right atrium and from the normal right atrium. Control experiments on ventricular trabeculae from the pig failed to show an inotropic response to the prostacyclin mimetics. qPCR demonstrated varying expression of the different prostanoid receptors in the human atrium. In conclusion, prostacyclin mimetics did not increase the force of contraction of human atrial trabeculae from the normal or the pressure-overloaded right heart. These data suggest that prostacyclin mimetics have no direct inotropic effects in the human right atrium

    The Relationship Between Financial Distress and Life-Course Socioeconomic Inequalities in Well-Being:Cross-National Analysis of European Welfare States

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    Objectives. We investigated to what extent current financial distress explains the relationship between life-course socioeconomic position and well-being in Southern, Scandinavian, Postcommunist, and Bismarckian welfare regimes. Methods. We analyzed individuals (n = 18 324) aged 50 to 75 years in the Survey of Health, Ageing, and Retirement in Europe, 2006–2009. Well-being was measured with CASP-12 (which stands for control, autonomy, self-realization, and pleasure) and life satisfaction. We generated a life-course socioeconomic index from 8 variables and calculated multilevel regression models (containing individuals nested within 13 countries), as well as stratified single-level models by welfare regime. Results. Life-course socioeconomic advantage was related to higher well-being; the difference in life satisfaction between the most and least advantaged was 2.09 (95% confidence interval = 1.87, 2.31) among women and 1.65 (95% confidence interval = 1.43, 1.87) among men. The weakest associations were found among Scandinavian countries. Financial distress was associated with lower well-being and attenuated the relationship between life-course socioeconomic position and well-being in all regimes (ranging from 34.26% in Postcommunist to 72.22% in Scandinavian countries). Conclusions. We found narrower inequalities in well-being in the Scandinavian regime. Reducing financial distress may help improve well-being and reduce inequalities

    Aerobic capacity, activity levels and daily energy expenditure in male and female adolescents of the kenyan nandi sub-group

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    The relative importance of genetic and socio-cultural influences contributing to the success of east Africans in endurance athletics remains unknown in part because the pre-training phenotype of this population remains incompletely assessed. Here cardiopulmonary fitness, physical activity levels, distance travelled to school and daily energy expenditure in 15 habitually active male (13.9±1.6 years) and 15 habitually active female (13.9±1.2) adolescents from a rural Nandi primary school are assessed. Aerobic capacity ([Formula: see text]) was evaluated during two maximal discontinuous incremental exercise tests; physical activity using accelerometry combined with a global positioning system; and energy expenditure using the doubly labelled water method. The [Formula: see text] of the male and female adolescents were 73.9±5.7 ml(.) kg(-1.) min(-1) and 61.5±6.3 ml(.) kg(-1.) min(-1), respectively. Total time spent in sedentary, light, moderate and vigorous physical activities per day was 406±63 min (50% of total monitored time), 244±56 min (30%), 75±18 min (9%) and 82±30 min (10%). Average total daily distance travelled to and from school was 7.5±3.0 km (0.8-13.4 km). Mean daily energy expenditure, activity-induced energy expenditure and physical activity level was 12.2±3.4 MJ(.) day(-1), 5.4±3.0 MJ(.) day(-1) and 2.2±0.6. 70.6% of the variation in [Formula: see text] was explained by sex (partial R(2) = 54.7%) and body mass index (partial R(2) = 15.9%). Energy expenditure and physical activity variables did not predict variation in [Formula: see text] once sex had been accounted for. The highly active and energy-demanding lifestyle of rural Kenyan adolescents may account for their exceptional aerobic fitness and collectively prime them for later training and athletic success

    Five-year stability in associations of health-related quality of life measures in community-dwelling older adults: the Rancho Bernardo Study

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    Ó The Author(s) 2010. This article is published with open access at Springerlink.com Objective This study examines the five-year stability of the association of SF-12 and SF-6D scores with scores on the longer SF-36 and its domains in community-dwelling older men and women. Methods Participants were 653 men and 917 women aged 50 and older who completed mailed surveys of HRQOL (1995, 2000). SF-36 physical (PCS) and mental (MCS) component scores, domain scores; SF-12 PCS and MCS scores; and SF-6D scores were computed. Results Average age in 1995 was 68.2 ± 10.7 for men and 69.8 ± 11.3 for women. In 1995 and 2000, men had significantly higher scores on all measures (P’s \ 0.001). All three authors have contributed to the conception and design of the work and data analysis plan, interpretation of the data, and preparing the manuscript for publication. The second and third authors were in charge of the acquisition of subjects. The first author conducted the data analysis and wrote the first draft which was revised by the second and third authors. All authors were involved with the data in a manner substantial enough to take public responsibility for it. All authors believe the manuscript represents valid work and have reviewed the final version of the manuscript and approve of it for publication

    Long-Term Mortality in Patients with Tuberculous Meningitis: A Danish Nationwide Cohort Study

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    Background: With high short-term mortality and substantial excess morbidity among survivors, tuberculous meningitis (TBM) is the most severe manifestation of extra-pulmonary tuberculosis (TB). The objective of this study was to assess the long-term mortality and causes of death in a TBM patient population compared to the background population. Methods: A nationwide cohort study was conducted enrolling patients notified with TBM in Denmark from 1972–2008 and alive one year after TBM diagnosis. Data was extracted from national registries. From the background population we identified a control cohort of individuals matched on gender and date of birth. Kaplan-Meier survival curves and Cox regression analysis were used to estimate mortality rate ratios (MRR) and analyse causes of death. Findings: A total of 55 TBM patients and 550 individuals from the background population were included in the study. Eighteen patients (32.7%) and 107 population controls (19.5%) died during the observation period. The overall MRR was 1.79 (95%CI: 1.09–2.95) for TBM patients compared to the population control cohort. TBM patients in the age group 31–60 years at time of diagnosis had the highest relative risk of death (MRR 2.68; 95%CI 1.34–5.34). The TBM patients had a higher risk of death due to infectious disease, but not from other causes of death. Conclusion: Adult TBM patients have an almost two-fold increased long-term mortality and the excess mortality stems fro

    Mechanical Metamaterials with Negative Compressibility Transitions

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    When tensioned, ordinary materials expand along the direction of the applied force. Here, we explore network concepts to design metamaterials exhibiting negative compressibility transitions, during which a material undergoes contraction when tensioned (or expansion when pressured). Continuous contraction of a material in the same direction of an applied tension, and in response to this tension, is inherently unstable. The conceptually similar effect we demonstrate can be achieved, however, through destabilisations of (meta)stable equilibria of the constituents. These destabilisations give rise to a stress-induced solid-solid phase transition associated with a twisted hysteresis curve for the stress-strain relationship. The strain-driven counterpart of negative compressibility transitions is a force amplification phenomenon, where an increase in deformation induces a discontinuous increase in response force. We suggest that the proposed materials could be useful for the design of actuators, force amplifiers, micro-mechanical controls, and protective devices.Comment: Supplementary information available at http://www.nature.com/nmat/journal/v11/n7/abs/nmat3331.htm
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