6,602 research outputs found

    Photoionization models of the CALIFA HII regions. I. Hybrid models

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    Photoionization models of HII regions require as input a description of the ionizing SED and of the gas distribution, in terms of ionization parameter U and chemical abundances (e.g. O/H and N/O). A strong degeneracy exists between the hardness of the SED and U, which in turn leads to high uncertainties in the determination of the other parameters, including abundances. One way to resolve the degeneracy is to fix one of the parameters using additional information. For each of the ~ 20000 sources of the CALIFA HII regions catalog, a grid of photoionization models is computed assuming the ionizing SED being described by the underlying stellar population obtained from spectral synthesis modeling. The ionizing SED is then defined as the sum of various stellar bursts of different ages and metallicities. This solves the degeneracy between the shape of the ionizing SED and U. The nebular metallicity (associated to O/H) is defined using the classical strong line method O3N2 (which gives to our models the status of "hybrids"). The remaining free parameters are the abundance ratio N/O and the ionization parameter U, which are determined by looking for the model fitting [NII]/Ha and [OIII]/Hb. The models are also selected to fit [OII]/Hb. This process leads to a set of ~ 3200 models that reproduce simultaneously the three observations. We find that the regions associated to young stellar bursts suffer leaking of the ionizing photons, the proportion of escaping photons having a median of 80\%. The set of photoionization models satisfactorily reproduces the electron temperature derived from the [OIII]4363/5007 line ratio. We determine new relations between the ionization parameter U and the [OII]/[OIII] or [SII]/[SIII] line ratios. New relations between N/O and O/H and between U and O/H are also determined. All the models are publicly available on the 3MdB database.Comment: Accepted for publication in A&

    Disparities among 2009 pandemic influenza A (H1N1) hospital admissions: A mixed methods analysis - Illinois, April-December 2009

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    During late April 2009, the first cases of 2009 pandemic influenza A (H1N1) (pH1N1) in Illinois were reported. On-going, sustained local transmission resulted in an estimated 500,000 infected persons. We conducted a mixed method analysis using both quantitative (surveillance) and qualitative (interview) data; surveillance data was used to analyze demographic distribution of hospitalized cases and follow-up interview data was used to assess health seeking behavior. Invitations to participate in a telephone interview were sent to 120 randomly selected Illinois residents that were hospitalized during April-December 2009. During April-December 2009, 2,824 pH1N1 hospitalizations occurred in Illinois hospitals; median age (interquartile range) at admission was 24 (range: 6-49) years. Hospitalization rates/100,000 persons for blacks and Hispanics, regardless of age or sex were 2-3 times greater than for whites (blacks, 36/100,000 (95% Confidence Interval ([95% CI], 33-39)); Hispanics, 35/100,000 [95%CI,32-37] (; whites, 13/100,000[95%CI, 12-14); p<0.001). Mortality rates were higher for blacks (0.9/100,000; p<0.09) and Hispanics (1/100,000; p<0.04) when compared with the mortality rates for whites (0.6/ 100,000). Of 33 interview respondents, 31 (94%) stated that they had heard of pH1N1 before being hospitalized, and 24 (73%) did not believed they were at risk for pH1N1. On average, respondents reported experiencing symptoms for 2 days (range: 1-7) before seeking medical care. When asked how to prevent pH1N1 infection in the future, the most common responses were getting vaccinated and practicing hand hygiene. Blacks and Hispanics in Illinois experienced disproportionate pH1N1 hospitalization and mortality rates. Public health education and outreach efforts in preparation for future influenza pandemics should include prevention messaging focused on perception of risk, and ensure community wide access to prevention messages and practices

    Resolving the age bimodality of galaxy stellar populations on kpc scales

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    Galaxies in the local Universe are known to follow bimodal distributions in the global stellar populations properties. We analyze the distribution of the local average stellar-population ages of 654,053 sub-galactic regions resolved on ~1-kpc scales in a volume-corrected sample of 394 galaxies, drawn from the CALIFA-DR3 integral-field-spectroscopy survey and complemented by SDSS imaging. We find a bimodal local-age distribution, with an old and a young peak primarily due to regions in early-type galaxies and star-forming regions of spirals, respectively. Within spiral galaxies, the older ages of bulges and inter-arm regions relative to spiral arms support an internal age bimodality. Although regions of higher stellar-mass surface-density, mu*, are typically older, mu* alone does not determine the stellar population age and a bimodal distribution is found at any fixed mu*. We identify an "old ridge" of regions of age ~9 Gyr, independent of mu*, and a "young sequence" of regions with age increasing with mu* from 1-1.5 Gyr to 4-5 Gyr. We interpret the former as regions containing only old stars, and the latter as regions where the relative contamination of old stellar populations by young stars decreases as mu* increases. The reason why this bimodal age distribution is not inconsistent with the unimodal shape of the cosmic-averaged star-formation history is that i) the dominating contribution by young stars biases the age low with respect to the average epoch of star formation, and ii) the use of a single average age per region is unable to represent the full time-extent of the star-formation history of "young-sequence" regions.Comment: 17 pages, 11 figures, MNRAS accepte

    Effectiveness of a healthy lifestyle promotion program as adjunctive teletherapy for treatment-resistant major depression during COVID 19 pandemic: A randomized clinical trial protocol

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    INTRODUCTION: Treatment-resistant depression (TRD) has a high prevalence and can be exacerbated by poor physical health and economic hardships, which have become common stressors during the current COVID-19 pandemic. The therapeutic approaches used to treat these patients are not always available, may be not be accepted by some patients, and often require face-to-face interactions. OBJECTIVE: The main aim of this study will be to evaluate the effectiveness of an Internet-based adjuvant lifestyle-based intervention for patients with TRD. METHODS: This will be a parallel, randomized, and controlled clinical trial. A total of 180 patients with TRD will be randomly allocated (1:1:1) to 1 of 3 groups: treatment prescribed by the mental health team and written suggestions for lifestyle changes (placebo control group); treatment prescribed by the mental health team, written suggestions for lifestyle changes, and an 8-week mindfulness-based cognitive therapy program (active control group); or treatment prescribed by the mental health team, written suggestions for lifestyle changes, and an 8-week lifestyle change promotion program (intervention group). We will perform this study during the COVID-19 pandemic, and will administer interventions by teletherapy, and contact participants by telephone calls, text messages, and/or teleconferences. We will collect patient data using questionnaires administered at baseline, immediately after the intervention, and after 6 and 12 months. The primary outcome will be score on the Beck Depression Inventory-II. The secondary outcomes will be score on the Clinical Global Impressions Scale (used to quantify and track patient progress and treatment response over time) and health-related quality of life measured using the European Quality of Life-5 Dimensions Questionnaire. DISCUSSION: Patients with TRD are especially vulnerable when face-to-face psychotherapy is unavailable. The main strength of the proposed study is the novelty of the intervention to be used as an adjuvant therapy. Our results may provide guidance for treatment of patients with TRD in future situations that require lockdown measures. CLINICALTRIALS REGISTRATION NUMBER: NCT04428099

    Coupled-mode theory for Bose-Einstein condensates

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    We apply the concepts of nonlinear guided-wave optics to a Bose-Einstein condensate (BEC) trapped in an external potential. As an example, we consider a parabolic double-well potential and derive coupled-mode equations for the complex amplitudes of the BEC macroscopic collective modes. Our equations describe different regimes of the condensate dynamics, including the nonlinear Josephson effect for any separation between the wells. We demonstrate macroscopic self-trapping for both repulsive and attractive interactions, and confirm our results by numerical simulations.Comment: 4 pages, 5 figures; typos removed, figures amended; submitted to PR

    Supersymmetric (non-)Abelian Bundles in the Type I and SO(32) Heterotic String

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    We discuss perturbative four-dimensional compactifications of both the SO(32) heterotic and the Type I string on smooth Calabi-Yau manifolds endowed with general non-abelian and abelian bundles. We analyse the generalized Green-Schwarz mechanism for multiple anomalous U(1) factors and derive the generically non-universal one-loop threshold corrections to the gauge kinetic function as well as the one-loop corrected Fayet-Iliopoulos terms. The latter can be interpreted as a stringy one-loop correction to the Donaldson-Uhlenbeck-Yau condition. Applying S-duality, for the Type I string we obtain the perturbative Pi-stability condition for non-abelian bundles on curved spaces. Some simple examples are given, and we qualitatively discuss some generic phenomenological aspects of this kind of string vacua. In particular, we point out that in principle an intermediate string scale scenario with TeV scale large extra dimensions might be possible for the heterotic string.Comment: LaTeX, 32 pages, v2: refs adde

    Time-Dependent Variational Analysis of Josephson Oscillations in a Two-component Bose-Einstein Condensate

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    The dynamics of Josephson-like oscillations between two coupled Bose-Einstein condensates is studied using the time-dependent variational method. We suppose that the quantum state of the condensates is a gaussian wave-packet which can translate and perform breathing shape oscillations. Under this hypotheses we study the influence of these degrees of freedom on the tunneling dynamics by comparing the full-model with one where these degrees of freedom are ``frozen'' at its equilibrium values. The result of our calculation shows that when the traps are not displaced the two models agree, whereas when they are, the models differ considerably, the former being now closer to its linear approximation.Comment: 10 pages, 2 figure

    Risk Factors for Nonaccidental Burns in Children

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    BACKGROUND: The relative influences of baseline risk factors for pediatric nonaccidental burns have not been well described. We evaluated baseline characteristics of pediatric nonaccidental burn patients and their primary caretakers. METHODS: A single-center retrospective cohort study was conducted of pediatric (age \u3c 17) burn patients from July 1, 2013, to June 30, 2018. The primary outcome was nonaccidental burn, defined as burn secondary to abuse or neglect as determined by the inpatient child protection team or Child Protective Services. Univariate and multivariate analyses were performed. RESULTS: Of 489 burn patients, 47 (9.6%) suffered nonaccidental burns. Nonaccidental burn patients more frequently had a history of Child Protective Services involvement (48.9% vs 9.7%, P \u3c .001), as did their primary caretakers (59.6% vs 10.9%, P \u3c .001). Non-Hispanic black children had higher rates of Child Protective Services referral (50.7% vs 26.7%, P \u3c .001) and nonaccidental burn diagnosis (18.9% vs 5.6%, P \u3c .001) than children of other races/ethnicities. On multivariate analysis, caretaker involvement with CPS (odds ratio 7.53, 95% confidence interval 3.38-16.77) and non-Hispanic black race/ethnicity (odds ratio 3.28, 95% confidence interval 1.29-8.36) were associated with nonaccidental burn. CONCLUSION: Caretaker history of Child Protective Services involvement and non-Hispanic black race/ethnicity were associated with increased odds of pediatric nonaccidental burn. Prospective research is necessary to determine whether these represent true risk factors for nonaccidental burn or are the result of other confounders, such as socioeconomic status

    Ionized gas kinematics of galaxies in the CALIFA survey I: Velocity fields, kinematic parameters of the dominant component, and presence of kinematically distinct gaseous systems

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    This work provides an overall characterization of the kinematic behavior of the ionized gas of the galaxies included in the Calar Alto Legacy Integral field Area (CALIFA), offering kinematic clues to potential users of this survey for including kinematical criteria for specific studies. From the first 200 galaxies observed by CALIFA, we present the 2D kinematic view of the 177 galaxies satisfying a gas detection threshold. After removing the stellar contribution, we used the cross-correlation technique to obtain the radial velocity of the dominant gaseous component. The main kinematic parameters were directly derived from the radial velocities with no assumptions on the internal motions. Evidence of the presence of several gaseous components with different kinematics were detected by using [OIII] profiles. Most objects in the sample show regular velocity fields, although the ionized-gas kinematics are rarely consistent with simple coplanar circular motions. 35% of the objects present evidence of a displacement between the photometric and kinematic centers larger than the original spaxel radii. Only 17% of the objects in the sample exhibit kinematic lopsidedness when comparing receding and approaching sides of the velocity fields, but most of them are interacting galaxies exhibiting nuclear activity. Early-type galaxies in the sample present clear photometric-kinematic misaligments. There is evidence of asymmetries in the emission line profiles suggesting the presence of kinematically distinct gaseous components at different distances from the nucleus. This work constitutes the first determination of the ionized gas kinematics of the galaxies observed in the CALIFA survey. The derived velocity fields, the reported kinematic peculiarities and the identification of the presence of several gaseous components might be used as additional criteria for selecting galaxies for specific studies.Comment: 38 pages, 16 figures, 4 tables. Paper accepted for publication in A&

    Stellar Population gradients in galaxy discs from the CALIFA survey

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    While studies of gas-phase metallicity gradients in disc galaxies are common, very little has been done in the acquisition of stellar abundance gradients in the same regions. We present here a comparative study of the stellar metallicity and age distributions in a sample of 62 nearly face-on, spiral galaxies with and without bars, using data from the CALIFA survey. We measure the slopes of the gradients and study their relation with other properties of the galaxies. We find that the mean stellar age and metallicity gradients in the disc are shallow and negative. Furthermore, when normalized to the effective radius of the disc, the slope of the stellar population gradients does not correlate with the mass or with the morphological type of the galaxies. Contrary to this, the values of both age and metallicity at \sim2.5 scale-lengths correlate with the central velocity dispersion in a similar manner to the central values of the bulges, although bulges show, on average, older ages and higher metallicities than the discs. One of the goals of the present paper is to test the theoretical prediction that non-linear coupling between the bar and the spiral arms is an efficient mechanism for producing radial migrations across significant distances within discs. The process of radial migration should flatten the stellar metallicity gradient with time and, therefore, we would expect flatter stellar metallicity gradients in barred galaxies. However, we do not find any difference in the metallicity or age gradients in galaxies with without bars. We discuss possible scenarios that can lead to this absence of difference.Comment: 24 pages, 17 figures, accepted for publication in A&
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