5,608 research outputs found

    V1135 Herculis: a double-lined eclipsing binary with an Anomalous Cepheid

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    BVR light curves and radial velocities for the double-lined eclipsing binary V1135\,Her were obtained. The brighter component of V1135\,Her is a Cepheid variable with a pulsation period of 4.22433±\pm0.00026 days. The orbital period of the system is about 39.99782±\pm0.00233 days, which is the shortest value among the known Type\,II Cepheid binaries. The observed B, V, and R magnitudes were cleaned for the intrinsic variations of the primary star. The remaining light curves, consisting of eclipses and proximity effects, are obtained. Our analyses of the multi-colour light curves and radial velocities led to the determination of fundamental stellar properties of both components of the interesting system V1135\,Her. The system consists of two evolved stars, G1+K3 between giants and supergiants, with masses of M1_1=1.461±\pm0.054 \Msun ~and M2_2=0.504±\pm0.040 {\Msun} and radii of R1_1=27.1±\pm0.4 {\Rsun} and R2_2=10.4±\pm0.2 {\Rsun}. The pulsating star is almost filling its corresponding Roche lobe which indicates the possibility of mass loss or transfer having taken place. We find an average distance of d=7500±\pm450 pc using the BVR magnitudes and also the V-band extinction. Location in the Galaxy and the distance to the galactic plane with an amount of 1300 pc indicate that it probably belongs to the thick-disk population. Most of the observed and calculated parameters of the V1135\,Her and its location on the color-magnitude and period-luminosity diagrams lead to a classification of an Anomalous Cepheid.Comment: 25 pages, 9 Tables, 9 Figures, Accepted Revista Mexicana de Astronom\'ia y Astrof\'isica. arXiv admin note: substantial text overlap with arXiv:1211.120

    On the Influence of Magnetic Fields on the Structure of Protostellar Jets

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    We here present the first results of fully three-dimensional (3-D) MHD simulations of radiative cooling pulsed (time-variable) jets for a set of parameters which are suitable for protostellar outflows. Considering different initial magnetic field topologies in approximate equipartitionequipartition with the thermal gas, i.e., (i) a longitudinal, and (ii) a helical field, both of which permeating the jet and the ambient medium; and (iii) a purely toroidal field permeating only the jet, we find that the overall morphology of the pulsed jet is not very much affected by the presence of the different magnetic field geometries in comparison to a nonmagnetic calculation. Instead, the magnetic fields tend to affect essentially the detailed structure and emission properties behind the shocks at the head and at the pulse-induced internal knots, particularly for the helical and toroidal geometries. In these cases, we find, for example, that the HαH_\alpha emissivity behind the internal knots can be about three to four times larger than that of the purely hydrodynamical jet. We also find that some features, like the nose cones that often develop at the jet head in 2-D calculations involving toroidal magnetic fields, are smoothed out or absent in the 3-D calculations.Comment: 13 pages, 3 figures, Accepted by ApJ Letters after minor corrections (for high resolution figures, see http://www.iagusp.usp.br/~adriano/h.tar

    Spatial interactions in agent-based modeling

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    Agent Based Modeling (ABM) has become a widespread approach to model complex interactions. In this chapter after briefly summarizing some features of ABM the different approaches in modeling spatial interactions are discussed. It is stressed that agents can interact either indirectly through a shared environment and/or directly with each other. In such an approach, higher-order variables such as commodity prices, population dynamics or even institutions, are not exogenously specified but instead are seen as the results of interactions. It is highlighted in the chapter that the understanding of patterns emerging from such spatial interaction between agents is a key problem as much as their description through analytical or simulation means. The chapter reviews different approaches for modeling agents' behavior, taking into account either explicit spatial (lattice based) structures or networks. Some emphasis is placed on recent ABM as applied to the description of the dynamics of the geographical distribution of economic activities, - out of equilibrium. The Eurace@Unibi Model, an agent-based macroeconomic model with spatial structure, is used to illustrate the potential of such an approach for spatial policy analysis.Comment: 26 pages, 5 figures, 105 references; a chapter prepared for the book "Complexity and Geographical Economics - Topics and Tools", P. Commendatore, S.S. Kayam and I. Kubin, Eds. (Springer, in press, 2014

    Refugee migration and risk of schizophrenia and other non-affective psychoses: cohort study of 1.3 million people in Sweden.

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    OBJECTIVE:  To determine whether refugees are at elevated risk of schizophrenia and other non-affective psychotic disorders, relative to non-refugee migrants from similar regions of origin and the Swedish-born population. DESIGN:  Cohort study of people living in Sweden, born after 1 January 1984 and followed from their 14th birthday or arrival in Sweden, if later, until diagnosis of a non-affective psychotic disorder, emigration, death, or 31 December 2011. SETTING:  Linked Swedish national register data. PARTICIPANTS:  1 347 790 people, including people born in Sweden to two Swedish-born parents (1 191 004; 88.4%), refugees (24 123; 1.8%), and non-refugee migrants (132 663; 9.8%) from four major refugee generating regions: the Middle East and north Africa, sub-Saharan Africa, Asia, and Eastern Europe and Russia. MAIN OUTCOME MEASURES:  Cox regression analysis was used to estimate adjusted hazard ratios for non-affective psychotic disorders by refugee status and region of origin, controlling for age at risk, sex, disposable income, and population density. RESULTS:  3704 cases of non-affective psychotic disorder were identified during 8.9 million person years of follow-up. The crude incidence rate was 38.5 (95% confidence interval 37.2 to 39.9) per 100 000 person years in the Swedish-born population, 80.4 (72.7 to 88.9) per 100 000 person years in non-refugee migrants, and 126.4 (103.1 to 154.8) per 100 000 person years in refugees. Refugees were at increased risk of psychosis compared with both the Swedish-born population (adjusted hazard ratio 2.9, 95% confidence interval 2.3 to 3.6) and non-refugee migrants (1.7, 1.3 to 2.1) after adjustment for confounders. The increased rate in refugees compared with non-refugee migrants was more pronounced in men (likelihood ratio test for interaction χ(2) (df=2) z=13.5; P=0.001) and was present for refugees from all regions except sub-Saharan Africa. Both refugees and non-refugee migrants from sub-Saharan Africa had similarly high rates relative to the Swedish-born population. CONCLUSIONS:  Refugees face an increased risk of schizophrenia and other non-affective psychotic disorders compared with non-refugee migrants from similar regions of origin and the native-born Swedish population. Clinicians and health service planners in refugee receiving countries should be aware of a raised risk of psychosis in addition to other mental and physical health inequalities experienced by refugees

    Suicide risk in people with post-traumatic stress disorder: a cohort study of 3.1 million people in Sweden

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    BACKGROUND: It is unclear whether post-traumatic stress disorder [PTSD] is associated with suicide risk in the general population, whether this differs by sex, or what the population impact of PTSD is for suicide. METHODS: We constructed a nationwide cohort of all people living in Sweden, born 1973-1997, followed from their 14th birthday (or immigration, if later) until suicide, other death, emigration or 31 December 2016. We used Cox proportional hazards regression to estimate hazard ratios [HR], and calculated the population impact of PTSD on suicide. We included sensitivity analyses to explore effects of outcome and exposure definitions, and to account for potential competing risks. RESULTS: Of 3,177,706 participants, 22,361 (0•7%) were diagnosed with PTSD, and 6,319 (0•2%) died by suicide over 49•2 million person-years. Compared with women and men without PTSD, suicide rates were 6•74 (95%CI: 5•61-8•09) and 3•96 (95%CI: 3•12-5•03) times higher in those with PTSD, respectively, after sociodemographic adjustment. Suicide rates remained elevated in women (HR: 2•61; 95%CI: 2•16-3•14) and men (HR: 1•67; 95%CI: 1•31-2•12) after adjustment for previous psychiatric conditions; attenuation was driven by previous non-fatal suicide attempts. Findings were insensitive to definitions or competing risks. If causal, 1•6% (95%CI: 1•2-2•1) of general population suicides could be attributed to PTSD, and up to 53.7% (95%CI: 46.1-60.2) in people with PTSD. LIMITATIONS: Residual confounding remains possible due to depressive and anxiety disorders diagnosed in primary care but unrecorded in these registers. CONCLUSIONS: Clinical guidelines for the management of people with PTSD should recognise increased suicide risk

    Inequalities in Psychiatric Service Use and Mortality by Migrant Status Following a First Diagnosis of Psychotic Disorder: A Swedish Cohort Study of 1.3M People

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    It is unclear whether inequalities in mental healthcare and mortality following the onset of psychosis exist by migrant status and region-of-origin. We investigated whether (1) mortality (including by major causes of death); (2) first admission type (inpatient or outpatient); (3) in-patient length of stay (LOS) at first diagnosis for psychotic disorder presentation, and; (4) time-to-readmission for psychotic disorder differed for refugees, non-refugee migrants, and by region-of-origin. We established a cohort of 1 335 192 people born 1984-1997 and living in Sweden from January 1, 1998, followed from their 14th birthday or arrival to Sweden, until death, emigration, or December 31, 2016. People with ICD-10 psychotic disorder (F20-33; N = 9399) were 6.7 (95% confidence interval [95%CI]: 5.9-7.6) times more likely to die than the general population, but this did not vary by migrant status (P = .15) or region-of-origin (P = .31). This mortality gap was most pronounced for suicide (adjusted hazard ratio [aHR]: 12.2; 95% CI: 10.4-14.4), but persisted for deaths from other external (aHR: 5.1; 95%CI: 4.0-6.4) and natural causes (aHR: 2.3; 95%CI: 1.6-3.3). Non-refugee (adjusted odds ratio [aOR]: 1.4, 95%CI: 1.2-1.6) and refugee migrants (aOR: 1.4, 95%CI: 1.1-1.8) were more likely to receive inpatient care at first diagnosis. No differences in in-patient LOS at first diagnosis were observed by migrant status. Sub-Saharan African migrants with psychotic disorder were readmitted more quickly than their Swedish-born counterparts (adjusted sub-hazard ratio [sHR]: 1.2; 95%CI: 1.1-1.4). Our findings highlight the need to understand the drivers of disparities in psychosis treatment and the mortality gap experienced by all people with disorder, irrespective of migrant status or region-of-origin

    Magnetic Field Effects on the Structure and Evolution of Overdense Radiatively Cooling Jets

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    We investigate the effect of magnetic fields on the propagation dynamics and morphology of overdense, radiatively cooling, supermagnetosonic jets, with the help of fully three-dimensional SPMHD simulations. Evaluated for a set of parameters which are mainly suitable for protostellar jets (with density ratios between the jet and the ambient medium 3-10, and ambient Mach number ~ 24), these simulations are also compared with baseline non-magnetic and adiabatic calculations. We find that, after amplification by compression and re-orientation in nonparallel shocks at the working surface, the magnetic field that is carried backward with the shocked gas into the cocoon improves the jet collimation relative to the purely hydrodynamic (HD) systems. Low-amplitude, approximately equally spaced internal shocks (which are absent in the HD systems) are produced by MHD K-H reflection pinch modes. The longitudinal field geometry also excites non-axisymmetric helical modes which cause some beam wiggling. The strength and amount of these modes are, however, reduced (by ~ twice) in the presence of radiative cooling relative to the adiabatic cases. Besides, a large density ratio between the jet and the ambient medium also reduces, in general, the number of the internal shocks. As a consequence, the weakness of the induced internal shocks makes it doubtful that the magnetic pinches could produce by themselves the bright knots observed in the overdense, radiatively cooling protostellar jets.Comment: To appear in ApJ; 36 pages + 16 (gif) figures. PostScript files of figures are available at http://www.iagusp.usp.br/preprints/preprint.htm

    Health and welfare profile of Australian baby boomers who live in rented accommodation – implications for the future

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    Incorrect spelling of Helen Barrie on the publication, left Statement of responsibility to reflect incorrect pdf.Baby boomers who rent are often overlooked as an important sub-group. We aimed to assess the chronic conditions, risk factors, socio-economic factors and other health-related factors associated with renting in private or public housing. Data from telephone interviews conducted each month in South Australia between and were combined. Prevalence estimates were assessed for each risk factor and chronic condition by housing status. The association between housing status and variables of interest were analysed using logistic regression models adjusting for multiple covariates (age, gender, income, smoking, physical activity, area and year of data collection). Overall, per cent of the baby boomers interviewed were renting, either privately or using government-subsided housing. The health profile of renters (both private and public) was poorer overall, with renters more likely to have all of the chronic conditions and ten risk factors assessed. For public renters the relationships were maintained even after controlling for socio-economic and risk factor variables for all chronic diseases except osteoporosis. This research has provided empirical evidence of the considerable differences in health, socio-economic indicators and risk factors between baby boomers who rent and those who own, or are buying, their own homes.Anne W. Taylor, Rhiannon Pilkington, Eleonora Dal Grande, Constance Kourbelis and Helen Barr

    The effect of local thermal fluctuations on the folding kinetics: a study from the perspective of the nonextensive statistical mechanics

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    Protein folding is a universal process, very fast and accurate, which works consistently (as it should be) in a wide range of physiological conditions. The present work is based on three premises, namely: (ii) folding reaction is a process with two consecutive and independent stages, namely the search mechanism and the overall productive stabilization; (iiii) the folding kinetics results from a mechanism as fast as can be; and (iiiiii) at nanoscale dimensions, local thermal fluctuations may have important role on the folding kinetics. Here the first stage of folding process (search mechanism) is focused exclusively. The effects and consequences of local thermal fluctuations on the configurational kinetics, treated here in the context of non extensive statistical mechanics, is analyzed in detail through the dependence of the characteristic time of folding (τ\tau) on the temperature TT and on the nonextensive parameter qq.The model used consists of effective residues forming a chain of 27 beads, which occupy different sites of a 3−3-D infinite lattice, representing a single protein chain in solution. The configurational evolution, treated by Monte Carlo simulation, is driven mainly by the change in free energy of transfer between consecutive configurations. ...Comment: 19 pages, 3 figures, 1 tabl

    Trends in levels of self-reported psychological distress among individuals who seek psychiatric services over eight years: a comparison between age groups in three population surveys in Stockholm County

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    BACKGROUND: Psychiatric service use has increased in Sweden and in other developed countries, particularly among young people. Possible explanations include lower threshold for help-seeking among young people, but evidence is scarce. METHODS: We analysed the 2002, 2006 and 2010 Stockholm public health surveys for changes in the mean level of psychological distress among adult users of psychiatric in- and outpatient services in four age groups: 18-24, 25-44, 45-64 and ≥65 years. Psychological distress was measured via the 12-item General Health Questionnaire (GHQ-12), using the Likert scoring method 0-1-2-3. In- and out-patient psychiatric service use within 6 months from the surveys was obtained from registers. RESULTS: The mean level of distress among young adults 18-24 years who utilize psychiatric services decreased between 2002 (mean GHQ-12 score, 95% confidence interval 20.5, 18.1-23.0) and 2010 (16.2, 14.6-17.7), while it remained fairly stable in older age groups. Results were similar in sex-stratified analyses, although the decrease was statistically significant only among young women 18-24 years. At the end of the follow-up, the level of distress among patients was similar for all age-groups. CONCLUSIONS: There were no differences between age groups in the level of distress when seeking care at the end of the follow-up period, supporting that there is no age-specific over- or under-consumption of psychiatric care in later years. However, the lowered threshold for help-seeking among young adults over time might have contributed to increases in psychiatric service use in the young age group. Public health policy and service delivery planning should consider the needs of the widening group of young users of psychiatric services
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