67 research outputs found

    Optical and Radio monitoring of S5 1803+74

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    The optical (BVRI) and radio (8.4 GHz) light curves of S5 1803+784 on a time span of nearly 6 years are presented and discussed. The optical light curve showed an overall variation greater than 3 mag, and the largest changes occured in three strong flares. No periodicity was found in the light curve on time scales up to a year. The variability in the radio band is very different, and shows moderate oscillations around an average constant flux density rather than relevant flares, with a maximum amplitude of ∌\sim30%, without a simultaneous correspondence between optical and radio luminosity. The optical spectral energy distribution was always well fitted by a power law. The spectral index shows small variations and there is indication of a positive correlation with the source luminosity. Possible explanations of the source behaviour are discussed in the framework of current models.Comment: 25 pages, 12 figure

    Multi-frequency VLBA study of the blazar S5 0716+714 during the active state in 2004: I. Inner jet kinematics

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    We observed the blazar \object{0716+714} with the VLBA during its active state in 2003-2004. In this paper we discuss multi-frequency analysis of the inner jet (first 1 mas) kinematics. The unprecedentedly dense time sampling allows us to trace jet components without misidentification and to calculate the component speeds with good accuracy. In the smooth superluminal jet we were able to identify and track three components over time moving outwards with relatively high apparent superluminal speeds (8.5-19.4 cc), which contradicts the hypothesis of a stationary oscillating jet in this source. Component ejections occur at a relatively high rate (once in two months), and they are accompanied by mm-continuum outbursts. Superluminal jet components move along wiggling trajectories, which is an indication of actual helical motion. Fast proper motion and rapid decay of the components suggest that this source should be observed with the VLBI at a rate of at least once in one or two months in order to trace superluminal jet components without confusion.Comment: 4 pages, 3 figures, Astronomy & Astrophysics Letter, language corrections adde

    BMJ Open

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    Objectives To investigate authors’ awareness and use of authorship guidelines, and to assess their perceptions of the fairness of authorship decisions. Design A cross-sectional online survey. Setting and participants Corresponding authors of research papers submitted in 2014 to 18 BMJ journals. Results 3859/12 646 (31%) researchers responded. They worked in 93 countries and varied in research experience. Of these, 1326 (34%) reported their institution had an authorship policy providing criteria for authorship; 2871 (74%) were ‘very familiar’ with the International Committee of Medical Journal Editors’ authorship criteria and 3358 (87%) reported that guidelines were beneficial when preparing manuscripts. Furthermore, 2609 (68%) reported that their use was ‘sometimes’ or ‘frequently’ encouraged in their research setting. However, 2859 respondents (74%) reported that they had been involved in a study at least once where someone was added as an author who had not contributed substantially (honorary authorship), and 1305 (34%) where someone was not listed as an author but had contributed substantially (ghost authorship). Only 740 (19%) reported that they had never experienced either honorary or ghost authorship; 1115 (29%) reported that they had experienced both at least once. There was no clear pattern in experience of authorship misappropriation by continent. For their last coauthored article, 2187 (57%) reported that explicit authorship criteria had been used to determine eligibility, and 3088 (80%) felt that the decision made was fair. When institutions frequently encouraged use of authorship guidelines, authorship eligibility was more likely to be discussed early (817 of 1410, 58%) and perceived as fairer (1273 of 1410, 90%) compared with infrequent encouragement (974 of 2449, 40%, and 1891 of 2449, 74%). Conclusions Despite a high level of awareness of authorship guidelines and criteria, these are not so widely used; more explicit encouragement of their use by institutions may result in more favourable use of guidelines by authors

    BMC Psychiatry

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    BACKGROUND: Depressive disorders in University students have risen dramatically in the past few decades to the extent that students' mental health has become a current global public health priority. Obtaining information from University students about their mental health is challenging because of potential embarrassment of disclosing one's concerns and fear of stigmatization. Self-rated health might be a good solution to evaluate mental health state by a simple and neutral indicator. The aim of the study is to investigate the association between depressive symptoms and self-rated health by sex among University students in France and Japan. METHODS: A cross-sectional study was conducted by using two large cohorts of students aged ≄18 years (n = 5655 in Bordeaux, France and n = 17,148 in Kyoto, Japan). Depressive symptoms (PHQ-2 scale), Likert scale of self-rated health, socio-demographic characteristics and health habits were collected through self-administered questionnaires. Multivariate logistic regression models were performed to describe the association between depressive symptoms and other variables including self-rated health, stratified by sex. RESULTS: A high score of PHQ-2 (high depressive symptoms) was associated with poor self-rated health in both cohorts independently of all other variables (OR 2.82, 95%CI 1.99-4.01 in France, OR 7.10, 95%CI 5.76-8.74 in Japan). Although the prevalence of depressive symptoms between sexes was different in French students (males 15.4%, females 25.0%, p < 0.001), it was similar in Japanese students (males 3.5%, females 3.3%, p = 0.466), who reported less depressive symptoms than French students. The association between depressive symptoms and poor self-rated health was greater in Japanese females (OR 12.40, 95%CI 7.74-20.00) than in males (OR 6.30, 95%CI 4.99-7.95), whereas the strength of the association was almost similar in French students (OR 2.17, 95%CI 0.86-5.47 in males, OR 2.98, 95%CI 2.03-4.38 in females). CONCLUSIONS: Depressive symptoms were associated with self-rated health among University students in both countries with slightly differences in sex. Self-rated health would be a simple, reliable and universal indicator for healthcare professionals and University staff to identify students at risk of depression

    Rms-flux relation in the optical fast variability data of BL Lacertae object S5 0716+714

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    The possibility that BL Lac S5 0716+714 exhibits a linear root mean square (rms)-flux relation in its IntraDay Variability (IDV) is analysed. The results may be used as an argument in the existing debate regarding the source of optical IDV in Active Galactic Nuclei. 63 time series in different optical bands were used. A linear rms-flux relation at a confidence level higher than 65% was recovered for less than 8% of the cases. We were able to check if the magnitude is log-normally distributed for eight timeseries and found, with a confidence > 95%, that this is not the case.Comment: Accepted by Astrophysics and Space Scienc

    Standard comparison of local mental health care systems in eight European countries

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    Aims. There is a need of more quantitative standardised data to compare local Mental Health Systems (MHSs) across international jurisdictions. Problems related to terminological variability and commensurability in the evaluation of services hamper like-with-like comparisons and hinder the development of work in this area. This study was aimed to provide standard assessment and comparison of MHS in selected local areas in Europe, contributing to a better understanding of MHS and related allocation of resources at local level and to lessen the scarcity in standard service comparison in Europe. This study is part of the Seventh Framework programme REFINEMENT (Research on Financing Systems’ Effect on the Quality of Mental Health Care in Europe) project. Methods. A total of eight study areas from European countries with different systems of care (Austria, England, Finland, France, Italy, Norway, Romania, Spain) were analysed using a standard open-access classification system (Description and Evaluation of Services for Long Term Care in Europe, DESDE-LTC). All publicly funded services universally accessible to adults (≄18 years) with a psychiatric disorder were coded. Care availability, diversity and capacity were compared across these eight local MHS. Results. The comparison of MHS revealed more community-oriented delivery systems in the areas of England (Hampshire) and Southern European countries (Verona – Italy and Girona – Spain). Community-oriented systems with a higher proportion of hospital care were identified in Austria (Industrieviertel) and Scandinavian countries (SĂžr-TrĂžndelag in Norway and Helsinki-Uusimaa in Finland), while Loiret (France) was considered as a predominantly hospital-based system. The MHS in Suceava (Romania) was still in transition to community care. Conclusions. There is a significant variation in care availability and capacity across MHS of local areas in Europe. This information is relevant for understanding the process of implementation of community-oriented mental health care in local areas. Standard comparison of care provision in local areas is important for context analysis and policy planning

    Radio-to-UV monitoring of AO 0235+164 by the WEBT and Swift during the 2006--2007 outburst

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    The blazar AO 0235+164 was claimed to show a quasi-periodic behaviour in the radio and optical bands. Moreover, an extra emission component contributing to the UV and soft X-ray flux was detected, whose nature is not yet clear. A predicted optical outburst was observed in late 2006/early 2007. We here present the radio-to-optical WEBT light curves during the outburst, together with UV data acquired by Swift in the same period. We found the optical outburst to be as strong as the big outbursts of the past: starting from late September 2006, a brightness increase of 5 mag led to the outburst peak in February 19-21, 2007. We also observed an outburst at mm and then at cm wavelengths, with an increasing time delay going toward lower frequencies during the rising phase. Cross-correlation analysis indicates that the 1 mm and 37 GHz flux variations lagged behind the R-band ones by about 3 weeks and 2 months, respectively. These short time delays suggest that the corresponding jet emitting regions are only slightly separated and/or misaligned. In contrast, during the outburst decreasing phase the flux faded contemporaneously at all cm wavelengths. This abrupt change in the emission behaviour may suggest the presence of some shutdown mechanism of intrinsic or geometric nature. The behaviour of the UV flux closely follows the optical and near-IR one. By separating the synchrotron and extra component contributions to the UV flux, we found that they correlate, which suggests that the two emissions have a common origin.Comment: 9 pages, 7 figures, in press for Astronomy and Astrophysic

    Multifrequency VLBA study of the blazar S5 0716+714 during the active state in 2004 II. Large-scale jet kinematics and the comparison of the different methods of VLBI data imaging as applied to kinematic studies of AGN

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    We study the jet kinematics of the blazar S5 0716+714 during its active state in 2003-2004 with multi-epoch VLBI observations. Aims. We present a kinematic analysis of the large-scale (0-12 mas) jet of 0716+714, based on the results of six epochs of VLBA monitoring at 5 GHz. Additionally, we compare kinematic results obtained with two imaging methods based on different deconvolution algorithms. The blazar 0716+714 has a diffuse large-scale jet and a very faint bright compact core. Experiments with simulated data showed that the conventional data reduction procedure based on the CLEAN deconvolution algorithm does not perform well in restoring this type of structure. This might be the reason why previous kinematic studies of this source yielded ambiguous results. In order to obtain accurate kinematics of this source, we independently applied two imaging techniques to the raw data: the conventional method, based on difference mapping, which uses CLEAN deconvolution, and the generalized maximum entropy method (GMEM) realized in the VLBImager package developed at the Pulkovo Observatory in Russia. The results of both methods give us a consistent kinematic scenario: the large-scale jet of 0716+714 is diffuse and stationary. Differences between the inner (0-1 mas) and outer (1-12 mas) regions of the jet in brightness and velocity of the components could be explained by the bending of the jet, which causes the angle between the jet direction and the line of sight to change from ~5 deg to ~11 deg. For the source 0716+714 both methods worked at the limit of their capability.Comment: 13 pages, 7 figures. Accepted for publication in A&A, 201

    Optical and radio behaviour of the BL Lacertae object 0716+714

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    Eight optical and four radio observatories have been intensively monitoring the BL Lac object 0716+714 in the last years: 4854 data points have been collected in the UBVRI bands since 1994, while radio light curves extend back to 1978. Many of these data are presented here for the first time. The long-term trend shown by the optical light curves seems to vary with a characteristic time scale of about 3.3 years, while a longer period of 5.5-6 years seems to characterize the radio long-term variations. In general, optical colour indices are only weakly correlated with brightness. The radio flux behaviour at different frequencies is similar, but the flux variation amplitude decreases with increasing wavelength. The radio spectral index varies with brightness (harder when brighter), but the radio fluxes seem to be the sum of two different-spectrum contributions: a steady base level and a harder-spectrum variable component. Once the base level is removed, the radio variations appear as essentially achromatic, similarly to the optical behaviour. Flux variations at the higher radio frequencies lead the lower-frequency ones with week-month time scales. The behaviour of the optical and radio light curves is quite different, the broad radio outbursts not corresponding in time to the faster optical ones and the cross-correlation analysis indicating only weak correlation with long time lags. However, minor radio flux enhancements simultaneous with the major optical flares can be recognized, which may imply that the mechanism producing the strong flux increases in the optical band also marginally affects the radio one.Comment: 18 pages, 15 Postscript figures, 5 JPEG figures, accepted for publication in A&

    Optical and radio variability of the BL Lac object AO 0235+16: a possible 5-6 year periodicity

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    New optical and radio data on the BL Lacertae object AO 0235+16 have been collected in the last four years by a wide international collaboration, which confirm the intense activity of this source. The optical data also include the results of the Whole Earth Blazar Telescope (WEBT) first-light campaign organized in November 1997. The optical spectrum is observed to basically steepen when the source gets fainter. We have investigated the existence of typical variability time scales and of possible correlations between the optical and radio emissions by means of visual inspection, Discrete Correlation Function analysis, and Discrete Fourier Transform technique. The major radio outbursts are found to repeat quasi-regularly with a periodicity of about 5.7 years; this period is also in agreement with the occurrence of some of the major optical outbursts, but not all of them.Comment: to be published in A&
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