3,620 research outputs found

    The influence of coronal EUV irradiance on the emission in the He I 10830 A and D3 multiplets

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    Two of the most attractive spectral windows for spectropolarimetric investigations of the physical properties of the plasma structures in the solar chromosphere and corona are the ones provided by the spectral lines of the He I 10830 A and 5876 A (or D3) multiplets, whose polarization signals are sensitive to the Hanle and Zeeman effects. However, in order to be able to carry out reliable diagnostics, it is crucial to have a good physical understanding of the sensitivity of the observed spectral line radiation to the various competing driving mechanisms. Here we report a series of off-the-limb non-LTE calculations of the He I D3 and 10830 A emission profiles, focusing our investigation on their sensitivity to the EUV coronal irradiation and the model atmosphere used in the calculations. We show in particular that the intensity ratio of the blue to the red components in the emission profiles of the He I 10830 A multiplet turns out to be a good candidate as a diagnostic tool for the coronal irradiance. Measurements of this observable as a function of the distance to the limb and its confrontation with radiative transfer modeling might give us valuable information on the physical properties of the solar atmosphere and on the amount of EUV radiation at relevant wavelengths penetrating the chromosphere from above.Comment: 19 pages, 11 figures (pre-print format). Accepted for publication in Ap

    Underground Neutrino Detectors for Particle and Astroparticle Science: the Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER)

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    The current focus of the CERN program is the Large Hadron Collider (LHC), however, CERN is engaged in long baseline neutrino physics with the CNGS project and supports T2K as recognized CERN RE13, and for good reasons: a number of observed phenomena in high-energy physics and cosmology lack their resolution within the Standard Model of particle physics; these puzzles include the origin of neutrino masses, CP-violation in the leptonic sector, and baryon asymmetry of the Universe. They will only partially be addressed at LHC. A positive measurement of sin22θ13>0.01\sin^22\theta_{13}>0.01 would certainly give a tremendous boost to neutrino physics by opening the possibility to study CP violation in the lepton sector and the determination of the neutrino mass hierarchy with upgraded conventional super-beams. These experiments (so called ``Phase II'') require, in addition to an upgraded beam power, next generation very massive neutrino detectors with excellent energy resolution and high detection efficiency in a wide neutrino energy range, to cover 1st and 2nd oscillation maxima, and excellent particle identification and π0\pi^0 background suppression. Two generations of large water Cherenkov detectors at Kamioka (Kamiokande and Super-Kamiokande) have been extremely successful. And there are good reasons to consider a third generation water Cherenkov detector with an order of magnitude larger mass than Super-Kamiokande for both non-accelerator (proton decay, supernovae, ...) and accelerator-based physics. On the other hand, a very massive underground liquid Argon detector of about 100 kton could represent a credible alternative for the precision measurements of ``Phase II'' and aim at significantly new results in neutrino astroparticle and non-accelerator-based particle physics (e.g. proton decay).Comment: 31 pages, 14 figure

    Critical sets of nonlinear Sturm-Liouville operators of Ambrosetti-Prodi type

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    The critical set C of the operator F:H^2_D([0,pi]) -> L^2([0,pi]) defined by F(u)=-u''+f(u) is studied. Here X:=H^2_D([0,pi]) stands for the set of functions that satisfy the Dirichlet boundary conditions and whose derivatives are in L^2([0,pi]). For generic nonlinearities f, C=\cup C_k decomposes into manifolds of codimension 1 in X. If f''0, the set C_j is shown to be non-empty if, and only if, -j^2 (the j-th eigenvalue of u -> u'') is in the range of f'. The critical components C_k are (topological) hyperplanes.Comment: 6 pages, no figure

    Small seed bank in grasslands and tree plantations in former grassland sites in the South Brazilian highlands

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    The soil seed bank can be an important source for vegetation regeneration, and data on the similarity between aboveground vegetation and the seed bank can provide information about successional pathways after disturbances or land‐use change. We conducted this study in natural grasslands in the subtropical highland region in southern Brazil. We evaluated the effect of silviculture on richness, density, and composition of the seed bank at former grassland sites converted to pine plantations 25 years ago. We worked at six grassland sites and three pine plantation sites and used the seedling emergence method. Seed bank density and richness in grasslands were lower than those reported in similar environments in other regions. Species richness and density varied considerably within each vegetation type; therefore, richness and density were not statistically significant, while composition varied among vegetation types. In terms of species, the pine plantation seed bank was a small subset of the grassland seed bank. Seeds of typical grassland species were missing in the pine plantation, but also had only low abundances in the grassland, and similarity of seed bank and vegetation were low (less than 20%). The low seed density found in this study, including in grasslands areas, indicates that regeneration of species from the soil seed bank likely is of a limited role for the maintenance of plant populations after disturbances in this system. Our data further suggest that natural regeneration after tree planting in grasslands is reduced due to seed limitation

    Reconstrucción de rotura crónica de tendón distal del bíceps braquial: a propósito de un caso

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    Las roturas inveteradas o crónicas del tendón distal del bíceps braquial son infrecuentes. Su tratamiento supone un reto importante por el grado de retracción y deficiente calidad del tendón y músculo lesionados, que en ocasiones obligan al empleo de injertos para tratar de restaurar la anatomía y mejorar los resultados funcionales. La tasa de complicaciones en las reparaciones de roturas crónicas es mayor con respecto a las reparaciones de lesiones agudas. Presentamos el caso de una reparación quirúrgica de una rotura crónica de 3 meses de evolución mediante la utilización de aloinjerto liofilizado de Aquiles.Chronic or inveterate disruptions of the distal biceps brachii are uncommon. Treatment remains a major challenge by shrinkage and poor quality of the injured tendon and muscle, which sometimes require the use of grafts to try to restore the anatomy and improve the functional outcomes. The rate of complications in surgical treatment of chronic tears is more than the repairs of acute injuries. We report the case of a surgical reconstruction of a chronic tear three months of evolution using lyophilized Achilles allograft

    Prevalence of depression during the COVID-19 outbreak: A meta-analysis of community-based studies

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    Introduction: COVID-19 pandemic, declared on March 11, 2020, constitute an extraordinary health, social and economic global challenge. The impact on people''s mental health is expected to be high. This paper sought to systematically review community-based studies on depression conducted during the COVID-19 and estimate the pooled prevalence of depression. Method: We searched for cross-sectional, community-based studies listed on PubMed or Web of Science from January 1, 2020 to May 8, 2020 that reported prevalence of depression. A random effect model was used to estimate the pooled proportion of depression. Results: A total of 12 studies were included in the meta-analysis, with prevalence rates of depression ranging from 7.45% to 48.30%. The pooled prevalence of depression was 25% (95% CI: 18% - 33%), with significant heterogeneity between studies (I2 = 99.60%, p < .001). Conclusions: Compared with a global estimated prevalence of depression of 3.44% in 2017, our pooled prevalence of 25% appears to be 7 times higher, thus suggesting an important impact of the COVID-19 outbreak on people's mental health. Addressing mental health during and after this global health crisis should be placed into the international and national public health agenda to improve citizens’ wellbeing

    The effects of physical activity interventions on glycated haemoglobin A1c in non-diabetic populations: a protocol for a systematic review and meta-analysis

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    Introduction Epidemiological evidence suggests that physical activity has a positive effect on reducing glycated haemoglobin A1c (HbA1c) levels not only in diabetics, but also in healthy subjects. Moreover, a positive association of HbA1c levels with cardiovascular disease and mortality in non-diabetic populations has recently been reported. This is a protocol for a systematic review and meta-analysis aiming to estimate the effects of physical activity on glycaemic control measured by HbA1c levels in non-diabetic populations; and to determine which type of physical activity has a greater influence on glycaemic control. Methods and analysis The search will be conducted using MEDLINE, EMBASE, the Cochrane Library and Web of Science databases from inception to mid-2017. Randomised controlled trials, non-randomised experimental studies and controlled pre–post studies written in English, Portuguese, French or Spanish will be included. The Cochrane Collaboration’s tool and The Quality Assessment Tool for Quantitative Studies will be used to assess the risk of bias for studies included in the systematic review. Standardised pre–post intervention mean differences of HbA1c will be calculated as the primary outcome. Subgroup analyses will be performed based on the characteristics of physical activity intervention and population included in the studies.This research received no specific grant from any funding agency in the public, commercial or not for profit sectors. IC-R is supported by a grant from the Universidad de Castilla-La Mancha (FPU13/01582). BP is supported by a grant from the Portuguese Foundation for Science and Technology (SFRH/BPD/108751/2015). CA-B and MG-M are supported by a grant from the Spanish Ministry of Ministry of Education, Culture and Sport (FPU13/03137 and FPU15/03847, respectively)

    Density matrix reconstruction from displaced photon number distributions

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    We consider state reconstruction from the measurement statistics of phase space observables generated by photon number states. The results are obtained by inverting certain infinite matrices. In particular, we obtain reconstruction formulas, each of which involves only a single phase space observable.Comment: 19 page

    The Effect of Physical Activity Interventions on Glycosylated Haemoglobin (HbA1c) in Non-diabetic Populations: A Systematic Review and Meta-analysis

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    Introduction Epidemiological evidence suggests that physical activity has a positive effect on reducing glycated haemoglobin A1c (HbA1c) levels not only in diabetics, but also in healthy subjects. Moreover, a positive association of HbA1c levels with cardiovascular disease and mortality in non-diabetic populations has recently been reported. This is a protocol for a systematic review and meta-analysis aiming to estimate the effects of physical activity on glycaemic control measured by HbA1c levels in non-diabetic populations; and to determine which type of physical activity has a greater influence on glycaemic control. Methods and analysis The search will be conducted using MEDLINE, EMBASE, the Cochrane Library and Web of Science databases from inception to mid-2017. Randomised controlled trials, non-randomised experimental studies and controlled pre–post studies written in English, Portuguese, French or Spanish will be included. The Cochrane Collaboration’s tool and The Quality Assessment Tool for Quantitative Studies will be used to assess the risk of bias for studies included in the systematic review. Standardised pre–post intervention mean differences of HbA1c will be calculated as the primary outcome. Subgroup analyses will be performed based on the characteristics of physical activity intervention and population included in the studies. Ethics and dissemination This systematic review will synthesise evidence on the association of physical activity and HbA1c in non-diabetic populations. This study is important from the clinical and public health point because it will estimate the effect of physical activity on the glycemic control, and it will also examine which is the type of physical activity that should be recommended for preventing type 2 diabetes and its complications. The results will be disseminated by publication in a peer-reviewed journal. Ethical approval will not be required because the data used for this systematic review will be obtained from published studies and there will be no concerns about privacy
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