1,021 research outputs found

    Coupled dark energy and dark matter from dilatation anomaly

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    Cosmological runaway solutions may exhibit an exact dilatation symmetry in the asymptotic limit of infinite time. In this limit, the massless dilaton or cosmon could be accompanied by another massless scalar field - the geon. At finite time, small time-dependent masses for both the cosmon and geon are still present due to imperfect dilatation symmetry. For a sufficiently large mass the geon will start oscillating and play the role of dark matter, while the cosmon is responsible for dark energy. The common origin of the mass of both fields leads to an effective interaction between dark matter and dark energy. Realistic cosmologies are possible for a simple form of the effective cosmon-geon-potential. We find an inverse geon mass of a size where it could reduce subgalactic structure formation.Comment: 4 pages, 2 figure

    Kahler potentials for the MSSM inflation and the spectral index

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    Recently it has been argued that some of the fine-tuning problems of the MSSM inflation associated with the existence of a saddle point along a flat direction may be solved naturally in a class of supergravity models. Here we extend the analysis and show that the constraints on the Kahler potentials in these models are considerably relaxed when the location of the saddle point is treated as a free variable. We also examine the effect of supergravity corrections on inflationary predictions and find that they can slightly alter the value of the spectral index. As an example, for flat direction field values ∣ϕˉ0∣=1×10−4MP|\bar{\phi}_0|=1\times10^{-4}M_P we find n∼0.92...0.94n\sim0.92 ... 0.94 while the prediction of the MSSM inflation without any corrections is n∼0.92n\sim0.92.Comment: 13 pages, one figure. Typos corrected and a reference adde

    Covariant generalization of cosmological perturbation theory

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    We present an approach to cosmological perturbations based on a covariant perturbative expansion between two worldlines in the real inhomogeneous universe. As an application, at an arbitrary order we define an exact scalar quantity which describes the inhomogeneities in the number of e-folds on uniform density hypersurfaces and which is conserved on all scales for a barotropic ideal fluid. We derive a compact form for its conservation equation at all orders and assign it a simple physical interpretation. To make a comparison with the standard perturbation theory, we develop a method to construct gauge-invariant quantities in a coordinate system at arbitrary order, which we apply to derive the form of the n-th order perturbation in the number of e-folds on uniform density hypersurfaces and its exact evolution equation. On large scales, this provides the gauge-invariant expression for the curvature perturbation on uniform density hypersurfaces and its evolution equation at any order.Comment: Minor changes to match the version published in PRD. RevTex, 22 pages, 1 figur

    Supergravity origin of the MSSM inflation

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    We consider the supergravity origin of the recently proposed MSSM inflationary model, which relies on the existence of a saddle point along a dimension six flat direction. We derive the conditions that the Kahler potential has to satisfy for the saddle point to exist irrespective of the hidden sector vevs. We show that these conditions are satisfied by a simple class of Kahler potentials, which we find to have a similar form as in various string theory compactifications. For these potentials, slow roll MSSM inflation requires no fine tuning of the soft supersymmetry breaking parameters.Comment: v3: 10 pages, no figures; version accepted for publication. Typos correcte

    A 10-Year Retrospective Study of 490 Hip Fracture Patients: Reoperations, Direct Medical Costs, and Survival

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    Background and Aims: Reoperations after operative treatment of hip fracture patients may be associated with higher costs and inferior survival. We examined the acute hospital costs, long-term reoperation rates, and survival of patients with a new hip fracture. Materials and Methods: A total of 490 consecutive new hip fracture patients treated at a single center between 31 December 2004 and 6 December 2006 were analyzed retrospectively. Fractures were classified according to Garden and AO. All medical records were checked manually. The costs of reoperations were calculated using the diagnosis-related groups (DRG)-based prices. Survival analysis was performed using the life-table method. The follow-up time was 10 years. Results: In all, 70/490 patients (14.3%) needed reoperations. Of all reoperations, 34.2% were performed during the first month and 72.9% within 1 year after the primary operation. The hemiarthroplasty dislocation rate was 8.5%, and mechanical failures of osteosynthesis occurred in 6.2%. Alcohol abuse was associated with a heightened risk of reoperation. The mean direct costs of primary fracture care were lower than the mean costs of reoperations (euro7500 vs euro9800). The mortality rate at 10 years was 79.8% among non-reoperated patients and 62.9% among reoperated patients. Conclusions: According to our hypothesis, the cost per patient of reoperation in acute care was 31% higher than the corresponding cost of a primary operation. Reoperations increased the overall immediate costs of index fractures by nearly 20%. One-third of all reoperations were performed during the first month and almost 75% within 1 year after the primary operation.Peer reviewe

    Does patient age affect survival after radical cystectomy?

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    OBJECTIVE To analyse the impact of patient age on survival after radical cystectomy (RC). PATIENTS AND METHODS After ethics review board approval, two databases of patients with bladder cancer (BC) undergoing RC at the University Heath Network, Toronto, Canada (1992-2008) and the University of Turku, Turku, Finland (1986-2005) were retrospectively analysed. A total of 605 patients who underwent this procedure between June 1985 and March 2010 were included. Patients were divided into four age groups: = 80 years. Demographic, clinical and pathological data were compared, as well as recurrence-free survival (RFS), disease-specific survival (DSS) and overall survival (OAS) rates. RESULTS Compared with younger patients (age = 80 years) had higher American Society of Anesthesiologists scores (P = 80 years (P = 80 years) should not be denied RC if they are deemed fit to undergo surgery. Senior adults do not suffer from adverse histopathological features as compared with younger patients

    healthcareCOVID: a national cross-sectional observational study identifying risk factors for developing suspected or confirmed COVID-19 in UK healthcare workers.

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    To establish the prevalence, risk factors and implications of suspected or confirmed coronavirus disease 2019 (COVID-19) infection among healthcare workers in the United Kingdom (UK). Cross-sectional observational study. UK-based primary and secondary care. Healthcare workers aged ≥18 years working between 1 February and 25 May 2020. A composite endpoint of laboratory-confirmed diagnosis of SARS-CoV-2, or self-isolation or hospitalisation due to suspected or confirmed COVID-19. Of 6,152 eligible responses, the composite endpoint was present in 1,806 (29.4%) healthcare workers, of whom 49 (0.8%) were hospitalised, 459 (7.5%) tested positive for SARS-CoV-2, and 1,776 (28.9%) reported self-isolation. Overall, between 11,870 and 21,158 days of self-isolation were required by the cohort, equalling approximately 71 to 127 working days lost per 1,000 working days. The strongest risk factor associated with the presence of the primary composite endpoint was increasing frequency of contact with suspected or confirmed COVID-19 cases without adequate personal protective equipment (PPE): 'Never' (reference), 'Rarely' (adjusted odds ratio 1.06, (95% confidence interval: [0.87-1.29])), 'Sometimes' (1.7 [1.37-2.10]), 'Often' (1.84 [1.28-2.63]), 'Always' (2.93, [1.75-5.06]). Additionally, several comorbidities (cancer, respiratory disease, and obesity); working in a 'doctors' role; using public transportation for work; regular contact with suspected or confirmed COVID-19 patients; and lack of PPE were also associated with the presence of the primary endpoint. A total of 1,382 (22.5%) healthcare workers reported lacking access to PPE items while having clinical contact with suspected or confirmed COVID-19 cases. Suspected or confirmed COVID-19 was more common in healthcare workers than in the general population and is associated with significant workforce implications. Risk factors included inadequate PPE, which was reported by nearly a quarter of healthcare workers. Governments and policymakers must ensure adequate PPE is available as well as developing strategies to mitigate risk for high-risk healthcare workers during future COVID-19 waves. [Abstract copyright: © 2021 Kua et al.

    The Subdominant Curvaton

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    We present a systematic study of the amplitude of the primordial perturbation in curvaton models with self-interactions, treating both renormalizable and non-renormalizable interactions. In particular, we consider the possibility that the curvaton energy density is subdominant at the time of the curvaton decay. We find that large regions in the parameter space give rise to the observed amplitude of primordial perturbation even for non-renormalizable curvaton potentials, for which the curvaton energy density dilutes fast. At the time of its decay, the curvaton energy density may typically be subdominant by a relative factor of 10^-3 and still produce the observed perturbation. Field dynamics turns out to be highly non-trivial, and for non-renormalizable potentials and certain regions of the parameter space we observe a non-monotonous relation between the final curvature perturbation and the initial curvaton value. In those cases, the time evolution of the primordial perturbation also displays an oscillatory behaviour before the curvaton decay.Comment: Acknowledgments of financial support added, no further change

    Follicle-Stimulating Hormone Levels and Subclinical Atherosclerosis in Older Postmenopausal Women

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    Recent studies of perimenopausal women suggest that follicle-stimulating hormone (FSH) levels may be associated with atherosclerosis, independent of estradiol. Whether FSH is related to atherosclerosis in older postmenopausal women, who have completed the menopausal transition, remains unknown. We assessed the relationship of serum FSH and estradiol levels with carotid artery intima-media thickness (IMT) among 587 postmenopausal participants in the Kuopio Ischemic Heart Disease Risk Factor Study (Kuopio, Finland). Participants were aged 53-73 years and not using hormone therapy at baseline (1998-2001). Mean IMT was measured via high-resolution ultrasonography. We observed a significant inverse association between FSH levels and IMT. Mean IMTs among women in quartiles 1-4 of FSH were 0.94 mm, 0.91 mm, 0.87 mm, and 0.85 mm, respectively (P-trend <0.001). After adjustment for age, estradiol, testosterone, body mass index (weight (kg)/height (m)(2)), lipids, and other factors, FSH levels remained significantly associated with IMT (regression coefficients for quartiles 2-4 vs. quartile 1 were -0.038, -0.045, and -0.062, respectively; P-trend = 0.01). Findings were strongest in women aged 64-73 years (P-trend = 0.006) and did not vary by body mass index. In contrast, estradiol levels were not related to IMT. In summary, high postmenopausal FSH levels were associated with a lower atherosclerotic burden, independent of estradiol, adiposity, and other factors. Our findings warrant replication and the further exploration of potential underlying mechanisms.Peer reviewe
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