154 research outputs found

    Dynamical generalization of a solvable family of two-electron model atoms with general interparticle repulsion

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    Holas, Howard and March [Phys. Lett. A {\bf 310}, 451 (2003)] have obtained analytic solutions for ground-state properties of a whole family of two-electron spin-compensated harmonically confined model atoms whose different members are characterized by a specific interparticle potential energy u(r12r_{12}). Here, we make a start on the dynamic generalization of the harmonic external potential, the motivation being the serious criticism levelled recently against the foundations of time-dependent density-functional theory (e.g. [J. Schirmer and A. Dreuw, Phys. Rev. A {\bf 75}, 022513 (2007)]). In this context, we derive a simplified expression for the time-dependent electron density for arbitrary interparticle interaction, which is fully determined by an one-dimensional non-interacting Hamiltonian. Moreover, a closed solution for the momentum space density in the Moshinsky model is obtained.Comment: 5 pages, submitted to J. Phys.

    Quantum Revivals in a Periodically Driven Gravitational Cavity

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    Quantum revivals are investigated for the dynamics of an atom in a driven gravitational cavity. It is demonstrated that the external driving field influences the revival time significantly. Analytical expressions are presented which are based on second order perturbation theory and semiclassical secular theory. These analytical results explain the dependence of the revival time on the characteristic parameters of the problem quantitatively in a simple way. They are in excellent agreement with numerical results

    l W nu production at CLIC: a window to TeV scale non-decoupled neutrinos

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    We discuss single heavy neutrino production e+ e- -> N nu -> l W nu, l = e, mu, tau, at a future high energy collider like CLIC, with a centre of mass energy of 3 TeV. This process could allow to detect heavy neutrinos with masses of 1-2 TeV if their coupling to the electron V_eN is in the range 0.004-0.01. We study the dependence of the limits on the heavy neutrino mass and emphasise the crucial role of lepton flavour in the discovery of a positive signal at CLIC energy. We present strategies to determine heavy neutrino properties once they are discovered, namely their Dirac or Majorana character and the size and chirality of their charged current couplings. Conversely, if no signal is found, the bound V_eN < 0.002-0.006 would be set for masses of 1-2 TeV, improving the present limit up to a factor of 30. We also extend previous work examining in detail the flavour and mass dependence of the corresponding limits at ILC, as well as the determination of heavy neutrino properties if they are discovered at this collider.Comment: LaTeX 32 pages. Added comments and references. Matches version to appear in JHE

    Prevalence of age-related macular degeneration in Spain

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    Aim: to estimate the prevalence of age-related maculopathy (ARM) and age-related macular degeneration (AMD) in the Spanish population aged ≥ 65 years. Methods: individuals were selected by random stratified sampling of census data from eight Spanish health districts encompassing a wide geographic area. Participants underwent an ophthalmologic evaluation including fundus imaging, and ARM and AMD were defined according to the International ARM Epidemiological Study Group classification. The age- and gender-adjusted prevalences and CIs for ARM and neovascular and atrophic forms of AMD were calculated. Results: of the 3028 individuals invited to participate, 2132 attended the ophthalmologic evaluation (840 men (70.9% response) and 1292 women (69.7% response); 978 aged 65-74 years (77.6% response), 1154 aged ≥ 75 years (65.3% response)). The overall prevalence of ARM and AMD was 10.3% (95% CI 8.7% to 11.8%) and 3.4% (95% CI 2.5% to 4.3%), respectively. AMD increased from 1.3% in individuals aged 65-74 years to 8.5% in those aged ≥ 80 years. Neovascular and atrophic AMD accounted for 1.9% and 1.5% of individuals, respectively. Conclusions: the prevalence of AMD in this large, population-based Spanish sample was similar to that observed in other large-scale population-based studies. However, the prevalence of ARM was lower than found in similar studies

    Signatures of Quark-Gluon-Plasma formation in high energy heavy-ion collisions: A critical review

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    A critical review on signatures of Quark-Gluon-Plasma formation is given and the current (1998) experimental status is discussed. After giving an introduction to the properties of QCD matter in both, equilibrium- and non-equilibrium theories, we focus on observables which may yield experimental evidence for QGP formation. For each individual observable the discussion is divided into three sections: first the connection between the respective observable and QGP formation in terms of the underlying theoretical concepts is given, then the relevant experimental results are reviewed and finally the current status concerning the interpretation of both, theory and experiment, is discussed. A comprehensive summary including an outlook towards RHIC is given in the final section.Comment: Topical review, submitted to Journal of Physics G: 68 pages, including 39 figures (revised version: only minor modifications, some references added

    Association of cataract and sun exposure in geographically diverse populations of India: The CASE study. First Report of the ICMR-EYE SEE Study Group.

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    PURPOSE: To determine the prevalence of cataract and its association with sun exposure and other environmental risk factors in three different geographically diverse populations of India. DESIGN: Population based cross sectional study during 2010-2016. PARTICIPANTS: People aged ≥ 40 years residing in randomly sampled villages were enumerated (12021) and 9735 (81%) underwent ophthalmic evaluation from plains, hilly and coastal regions (3595, 3231, 2909 respectively). METHODS: A detailed questionnaire-based interview about outdoor activity in present, past and remote past, usage of sun protective measures, exposure to smoke, and detailed ophthalmic examination including assessment of uncorrected and best corrected visual acuity, measurement of intraocular pressure, slit lamp examination, lens opacities categorization using LOCS III and posterior segment evaluation was done. Lifetime effective sun exposure was calculated using Melbourne formula and expressed as quintiles. These were supplemented with physical environmental measurements. MAIN OUTCOME MEASURES: Lifetime sun exposure hours, smoking, indoor kitchen smoke exposure and their association with cataract and subtypes. Prevalence of cataract calculated based on lens opacities or evidence of cataract surgery. RESULTS: Cataract was identified in 3231 (33.3%) participants. Prevalence of cataract in males (32.3%) and females (34.1%) was similar. Nuclear cataract was the commonest sub-type identified in 94.7% of affected eyes. Sun exposure had a significant association with cataract with odds ratio (OR) increasing from 1.6 (95% Confidence Intervals [CI]: 1.4, 1.9) in 3rd quintile, to 2.6 (CI: 2.2, 3.1) in 4th quintile and 9.4 (CI: 7.9, 11.2) in 5th quintile (p<0.0001). Cataract also showed a significant association with smoking (OR: 1.4, CI: 1.2, 1.6) and indoor kitchen smoke exposure (OR: 1.2, CI: 1.0-1.4). Nuclear cataract showed a positive association with increasing sun exposure in 3rd (β coefficient 0.5, CI:0.2-0.7), 4th (β: 0.9, CI: 0.7-1.1) and 5th (β: 2.1, CI:1.8-2.4) quintiles of sun exposure, smoking (β: 0.4, CI: 0.2-0.6) and indoor kitchen smoke exposure (β: 0.3, CI: 01-0.5) while cortical cataract showed a positive association with sun exposure only in 5th quintile (β: 2.6, CI:1.0-4.2). Posterior subcapsular cataract was not associated with any of the risk factors. CONCLUSION: Cataract is associated with increasing level of sun exposure, smoking and exposure to indoor kitchen smoke

    Therapeutic hypothermia in adult patients receiving extracorporeal life support: early results of a randomized controlled study

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    Cardiac arrest with cerebral ischaemia frequently leads to severe neurological impairment. Extracorporeal life support (ECLS) has emerged as a valuable adjunct in resuscitation of cardiac arrest. Despite ECLS, the incidence of permanent neurological injury remains high. We hypothesize that patients receiving ECLS for cardiac arrest treated with therapeutic hypothermia at 34 °C have lower neurological complication rates compared to standard ECLS therapy at normothermia. Early results of this randomized study suggest that therapeutic hypothermia is safe in adult patients receiving ECLS, with similar complication rates as ECLS without hypothermia. Further studies are warranted to measure the efficacy of this therapy

    The effects of recent stressful life events on outcomes in individuals at clinical high risk for psychosis:results from the longitudinal EU-GEI high-risk study

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    BACKGROUND: Recent stressful life events (SLE) are a risk factor for psychosis, but limited research has explored how SLEs affect individuals at clinical high risk (CHR) for psychosis. The current study investigated the longitudinal effects of SLEs on functioning and symptom severity in CHR individuals, where we hypothesized CHR would report more SLEs than healthy controls (HC), and SLEs would be associated with poorer outcomes.METHODS: The study used longitudinal data from the EU-GEI High Risk study. Data from 331 CHR participants were analyzed to examine the effects of SLEs on changes in functioning, positive and negative symptoms over a 2-year follow-up. We compared the prevalence of SLEs between CHR and HCs, and between CHR who did (CHR-T) and did not (CHR-NT) transition to psychosis.RESULTS: CHR reported 1.44 more SLEs than HC ( p &lt; 0.001), but there was no difference in SLEs between CHR-T and CHR-NT at baseline. Recent SLEs were associated with poorer functioning and more severe positive and negative symptoms in CHR individuals (all p &lt; 0.01) but did not reveal a significant interaction with time. CONCLUSIONS: CHR individuals who had experienced recent SLEs exhibited poorer functioning and more severe symptoms. However, as the interaction between SLEs and time was not significant, this suggests SLEs did not contribute to a worsening of symptoms and functioning over the study period. SLEs could be a key risk factor to becoming CHR for psychosis, however further work is required to inform when early intervention strategies mitigating against the effects of stress are most effective.</p
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