1,360 research outputs found

    Reduction and unfolding: the Kepler problem

    Full text link
    In this paper we show, in a systematic way, how to relate the Kepler problem to the isotropic harmonic oscillator. Unlike previous approaches, our constructions are carried over in the Lagrangian formalism dealing with second order vector fields. We therefore provide a tangent bundle version of the Kustaahneimo-Stiefel map.Comment: latex2e, 28 pages; misprints correcte

    Health Effects of Job Insecurity among Employees in Swiss General Population

    Get PDF
    Objectives. To investigate at national level the association between health and the social distress in which the whole employed population is plunged as a consequence of job insecurity. Design. Cross-sectional study. Setting. Switzerland. Subjects. Individuals working full or part time as employees drawn from a random sample (N=2024) of the Swiss general population interviewed by phone. Main outcome measures. Prevalence rates of ten self reported health and health related behaviour indicators according to three levels of perceived job insecurity (low, middle, high). Odds ratios estimated with logistic regression adjusted for relevant respondents characteristics (sex, age, education, having a chronic disease, working full or part-time and in public or private field). Results. One employee out of 10 experienced a high level of job insecurity, out of five a middle level while about 2/3 have no or a very low perception of job insecurity. The results clearly show that psychosocial stress induced in general employed population by fear of unemployment has a negative impact on the individual health and related health behaviour. A positive "dose-response" gradient was found between rise in job insecurity level's and the indicators investigated, suggesting a linear deterioration of health. In particular, employees in high insecurity group, compared to those in low one, have significantly higher odds ratios for seven indicators out of ten [not being in good health OR 1.6 (CI 1.0-2.7); high level of subjective stress OR 1.6 (CI 1.1-2.3); low self-esteem OR 2.9 (CI 1.5-5.7); daily or weekly consumption of tranquillisers OR 2.1 (CI 1.0-4.3); regular low-back pain OR 2.0 (CI 1.3-3.2); regular smoking OR 1.6 (CI 1.0-2.4); avoiding medical consultation or caring for themselves for fear of missing work OR 3.4 (CI 1.9-5.9)]. Employees with higher educational status seem to have more difficulties than less educated in coping with job insecurity. Conclusions. There is a positive association between health status and health related behaviour and social distress due to perception of job insecurity. Fear of unemployment seems to have stronger unfavourable effect in high educated employees than in less educated, probably because investment in career and in personal expectations are, in that group, generally higher. Although this cross-sectional study carried out at national level do not reach the "gold standard" represented by longitudinal ones, the results are fully consistent with those of few analysis on job insecurity carried out prospectively at firm level. Recommendations. In terms of concrete actions the main recommendations stemming from this study could be [i] to break the wall of silence generally erected around studies showing the positive relationship between job insecurity and deterioration of health, in order to promote a public and political consciousness in favour of less excluding and more solidary social and economic choices and [ii] to promote a systematic measure of health impact of policies and legislations with particular emphasis on those affecting labour market and work environment.economic development; labour market; unemployment; job insecurity; deprivation; health; public health; health impact assessment

    Optical and infrared polarimetry of the transient LMXB Cen X-4 in quiescence

    Full text link
    We present the first optical and infrared polarimetric study of the low mass transient X-ray binary Cen X-4 during its quiescent phase. This work is aimed to search for an intrinsic linear polarisation component in the system emitted radiation that might be due, e.g., to synchrotron emission from a compact jet, or to Thomson scattering with free electrons in an accretion disc. Multiband (BVRI) optical polarimetric observations were obtained during two nights in 2008 at the ESO La Silla 3.6 m telescope (EFOSC2) in polarimetric mode. These observations cover about the 30% of the 15.1 hours orbital period. J-band observations were obtained in 2007 with the NICS (TNG) instrument at La Palma, for a totality of 1 hour observation. We obtained 3-sigma upper limits to the polarisation degree in all the optical bands, with the most constraining one being in the I-band (P<0.5%). No phase-correlated variability has been noticed in all the filters. The J-band observations provided a 6% upper limit on the polarisation level. The constraining upper limits to the polarisation in the optical allowed us to evaluate the contribution of the possible emission of a relativistic particles jet to the total system radiation to be less then the 10%. This is in agreement with the observation of a spectral energy distribution typical of a single black body of a K-spectral type main sequence star irradiated from the compact object. Due to the low S/N ratio it was not possible to investigate the possible dependency of the polarisation degree from the wavelength, that could be suggestive of polarisation induced by Thomson scattering of radiation with free electrons in the outer part of the accretion disc. Observations with higher S/N ratio are required to examine in depth this hypothesis, searching for significant phase-correlated variability.Comment: 7 pages, 9 figures, accepted for publication in section 7. Stellar structure and evolution of Astronomy and Astrophysic

    The link between short Gamma-ray bursts and Gravitational Waves: perspectives for the THESEUS mission

    Get PDF
    The knowledge of the class of short Gamma-Ray Bursts (GRBs), characterised by a duration of the gamma-ray emission ≤2\leq 2 s, experienced an impressive boost in the last decade. In particular, the discovery of short GRB afterglows in 2005 with Swift and HETE-II provided the first insight into their energy scale, environments and host galaxies. The lack of detection of associated supernovae proved that they are not related to the death of massive stars. The increasing evidence for compact object binary progenitors makes short GRBs one of the most promising sources of gravitational waves for the forthcoming Advanced LIGO/Virgo science runs. To this end, the spectacular detection of the first electromagnetic counterpart of the gravitational wave event GW\,170817 originated by the coalescence of a double neutron star (NS) system, represents a first hystorical milestone. The (weak) short GRB\,170817A associated to this GW event provided the long-sought evidence that at least a fraction of short GRBs are originated by NS-NS merging and suggested the intriguing possibility that relativistic jets can be launched in the process of a NS-NS merger. The THESEUS mission, thanks to the diversity of intstrumentation, fast pointing and flexible schedule will represent a key facility in the multi-messenger astronomy era.Comment: To be published in the Proceedings of the THESEUS Workshop 2017 (http://www.isdc.unige.ch/theseus/workshop2017.html), Journal of the Italian Astronomical Society (Mem.SAIt), Editors L. Amati, E. Bozzo, M. Della Valle, D. Gotz, P. O'Brien. Details on the THESEUS mission concept can be found in the white paper Amati et al. 2017 (arXiv:171004638) and Stratta et al. 2017 (arXiv:1712.08153

    Reducing Barriers, Improving Outcomes: Using Federal Opportunities to Expand Health Care Access for Individuals with Limited English Proficiency

    Get PDF
    The United States' health care system consistently fails people whose primary language is not English, frequently known as individuals with limited English proficiency (LEP). These breakdowns result in increases in both unnecessary care due to misdiagnoses and poor health outcomes. Luckily, there are clear and actionable policy interventions that Congress and federal agencies can take to address these health disparities. By increasing the quality of languages services, making them more available, and strengthening both provider and patient understanding of existing rights and tools, we can improve the health of millions of families in the U.S

    Data-driven Social Mood Analysis through the Conceptualization of Emotional Fingerprints

    Get PDF
    Abstract A body of knowledge shows the emerging of evidence according to a better account for the emotional spectrum is achievable by employing a complete selection of emotion keywords. Basic emotions, such as Ekman's ones, cannot be considered universal, but are related to with implicit thematic affairs within the corpus under analysis. The paper tracks some preliminary experiments obtained by employing a data-driven methodology that captures emotions, relying on domain data that you want to model. The experimentation consists of investigating the corresponding conceptual space based on a set of terms (i.e., keywords) that are representative of the domain and the determination. Furthermore, the conceptual space is exploited as a bridge between the textual content and its sub-symbolic mapping as an "emotional fingerprint" into a six-dimensional hyperspace

    GRB 140206A: the most distant polarized Gamma-Ray Burst

    Full text link
    The nature of the prompt gamma-ray emission of Gamma-Ray Bursts (GRBs) is still far from being completely elucidated. The measure of linear polarization is a powerful tool that can be used to put further constraints on the content and magnetization of the GRB relativistic outflows, as well as on the radiation processes at work. To date only a handful of polarization measurements are available for the prompt emission of GRBs. Here we present the analysis of the prompt emission of GRB 140206A, obtained with INTEGRAL/IBIS, Swift/BAT, and Fermi/GBM. Using INTEGRAL/IBIS as a Compton polarimeter we were able to constrain the linear polarization level of the second peak of this GRB as being larger than 28% at 90% c.l. We also present the GRB afterglow optical spectroscopy obtained at the Telescopio Nazionale Galileo (TNG), which allowed us the measure the distance of this GRB, z=2.739. This distance value together with the polarization measure obtained with IBIS, allowed us to derive the deepest and most reliable limit to date (xi <1x10-16) on the possibility of Lorentz Invariance Violation, measured through the vacuum birefringence effect on a cosmological source.Comment: 9 pages, 5 figures, 3 tables, accepted for publication in MNRAS. arXiv admin note: text overlap with arXiv:1303.418
    • …
    corecore