The C IV Doublet Ratio Intensity Effect in Symbiotic Stars

The first successful high-resolution ultraviolet spectra in the λλ 1200-2000 wavelength range of the symbiotic variable R Aquarii and its nebular Jet were obtained in 1987 July with the International Ultraviolet Explorer (IUE). The line profile structure of the C IV λλ1548, 1550 doublet in the jet indicates multicomponent velocity structure from an optically thin emitting gas. The C IV doublet profiles in the compact H II region engulfing the Mira and hot companion binary also suggest multicomponent structure, in which the radial velocities range up to ~ -100 km s^- 1. The value of the doublet intensity ratio in the R Aqr H II region is I(λ1548)/ I(λ1550) ~0.6, which is less than the optically thick limit of unity, an effect which has also been observed in other similar symbiotic stars such as RX Pup. In the case of RX Pup, however, the C IV doublet intensity ratio was I(λ1548)/I(λ1550) ~0.6 during an enhanced phase of UV and optical emission, but became larger, acquiring a value ~1, as the star declined in light over a 5 yr period. The anomalous behavior of the C IV doublet intensities, which. we refer to as the C IV Doublet Ratio Intensity Effect, may provide an important tool for studying the spatial structure and temporal nature of winds in symbiotic stars

Indicators Associated With Job Morale Among Physicians and Dentists in Low-Income and Middle-Income Countries: A Systematic Review and Meta-analysis.

Importance: Improving health care in low- and middle-income countries (LMICs) requires a workforce with positive job morale. However, the level of job morale in this population remains unclear. Objective: To analyze studies measuring the job morale of physicians and dentists working in LMICs, using levels of job burnout, job satisfaction, and job motivation as indicators of job morale. Data Sources: A comprehensive search of Scopus, PubMed, PsycINFO, EMBASE, Web of Science, and the Cochrane Library, from database inception to October 30, 2018, and gray literature was performed. Study Selection: Studies were eligible if at least 50% of the sample were qualified physicians and/or dentists working in public health care settings in LMICs. Three indicators of job morale in this population were used: job burnout, job satisfaction, and job motivation. Of 12 324 records reviewed, 79 studies were included in the systematic review and 59 were eligible for the meta-analysis. Data Extraction And Synthesis: Data were extracted independently by several investigators in accordance with the Meta-analyses of Observational Studies in Epidemiology (MOOSE) reporting guidelines. Random-effects meta-analyses, planned subgroup analyses, and metaregression were performed. The Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies was used to assess bias. Main Outcomes and Measures: Levels of job burnout, job satisfaction, and job motivation as indicators of job morale. Results: Overall, 12 324 records were identified. Of them, 80 records, representing 79 studies and involving 45 714 participants across 37 LMICs, met the inclusion criteria for the review; however, only 3 were from low-income countries. In 21 studies with 9092 participants working mainly in middle-income countries, 32% (95% CI, 27%-38%; I2 = 95.32%; P < .001) reported job burnout, and in 20 studies with 14 113 participants, 60% (95% CI, 53%-67%; I2 = 98.21%; P < .001) were satisfied with their job overall. Sufficient data were not available for a meta-analysis of job motivation. Conclusions and Relevance: The findings suggest that, among physicians and dentists working mainly in middle-income countries, more than half reported having positive job morale. Positive job morale among physicians and dentists may help with recruitment and retention and thus support programs for improving health care in LMICs

A study of the expanding envelope of Nova V1974 Cyg 1992 based on IUE high resolution spectroscopy

We have carried out a detailed analysis of the IUE archival high resolution spectra of the classical nova V1974 Cyg 1992. In addition to the P Cygni and emission lines, two shortward shifted absorption systems are present. Evidence is given that these absorptions originate in two separate expanding shells, outside the wind layers where the emission lines are formed. The outer main shell, containing most of the matter ejected at outburst, produces the so-called ``principal absorption line system'', and the inner faster moving second shell produces the so-called ``diffuse--enhanced absorption line system''. The outflow velocity of the two shells increases exponentially with time reaching a value of about 1750 km/s and 2900 km/s, respectively. We suggest that the acceleration of the shells is the result of increasing line-radiation pressure due to the UV-brightening of the star as the effective radius decreases. Around day 60 the second shell has overtaken the slower moving principal system shell, and merged with it. This explains: the sudden disappearance of the diffuse line system near that date, the upward jump of 240 km/s in velocity of the principal system and the first detection of hard X-ray emission on day 63. This velocity jump indicates that the main shell is about 4 times more massive than the second shell. The deceleration suffered by the diffuse-enhanced system after the shock provides a shock temperature of about 1.6 KeV, in fairly good agreement with the temperature of the observed hard X-ray emission.Comment: 19 pages, 11 figure

Hard X-ray emission from Eta Carinae

Context : If relativistic particle acceleration takes place in colliding-wind binaries, hard X-rays and gamma-rays are expected through inverse Compton emission, but to date these have never been unambiguously detected. Aims : To detect this emission, observations of Eta Carinae were performed with INTEGRAL, leveraging its high spatial resolution. Methods : Deep hard X-ray images of the region of Eta Car were constructed in several energy bands. Results : The hard X-ray emission previously detected by BeppoSax around Eta Car originates from at least 3 different point sources. The emission of Eta Car itself can be isolated for the first time, and its spectrum unambiguously analyzed. The X-ray emission of Eta Car in the 22-100 keV energy range is very hard (photon index around 1) and its luminosity is 7E33 erg/s. Conclusions : The observed emission is in agreement with the predictions of inverse Compton models, and corresponds to about 0.1% of the energy available in the wind collision. Eta Car is expected to be detected in the GeV energy range.Comment: 5 pages with 2 figures. Accepted as a Letter in Astronomy & Astrophysic

Radiation measurements as tool for environmental and geophysics studies on volcano-tectonic areas

In the last years there has been an increasing concern about naturalradioactivity measurements both from the point of view of the environmental survey, especially for the human health protection, and of the geophysical-events investigation in volcanic areas and tectonic fault zones. We report on our activity in both these fields, in particular on the measurements of indoor radon concentration in a long-term passive monitoring in dwellings of the eastern region of Sicily. Because this region is characterized by high seismicity, besides the indoor radioactivity survey, in-soil radon measurements in the region (both volcanic and tectonic area) can provide a better insight and a valuable database for the study related to radon anomalies. A synthesis is reported of the results that we obtained, in the last years, in the volcanic and tectonic area of oriental Sicily both from indoor monitoring and from geophysical-events investigation

Illumination in symbiotic binary stars: Non-LTE photoionization models. II. Wind case

We describe a non-LTE photoionization code to calculate the wind structure and emergent spectrum of a red giant wind illuminated by the hot component of a symbiotic binary system. We consider spherically symmetric winds with several different velocity and temperature laws and derive predicted line fluxes as a function of the red giant mass loss rate, \mdot. Our models generally match observations of the symbiotic stars EG And and AG Peg for \mdot about 10^{-8} \msunyr to 10^{-7} \msunyr. The optically thick cross- section of the red giant wind as viewed from the hot component is a crucial parameter in these models. Winds with cross-sections of 2--3 red giant radii reproduce the observed fluxes, because the wind density is then high, about 10^9 cm^{-3}. Our models favor winds with acceleration regions that either lie far from the red giant photosphere or extend for 2--3 red giant radii.Comment: 51 pages, LaTeX including three tables, requires 15 Encapsulated Postscript figures, to appear in Ap

Physical structure of the photodissociation regions in NGC 7023: Observations of gas and dust emission with <i>Herschel</i>

The determination of the physical conditions in molecular clouds is a key step towards our understanding of their formation and evolution of associated star formation. We investigate the density, temperature, and column density of both dust and gas in the photodissociation regions (PDRs) located at the interface between the atomic and cold molecular gas of the NGC 7023 reflection nebula. We study how young stars affect the gas and dust in their environment. Our approach combining both dust and gas delivers strong constraints on the physical conditions of the PDRs. We find dense and warm molecular gas of high column density in the PDRs

Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. 5: Variability of the ultraviolet continuum and emission lines of NGC 3783

We report on the results of intensive ultraviolet spectral monitoring of the Seyfert 1 galaxy NGC 3783. The nucleus of NGC 3783 was observed with the International Ultraviolet Explorer satellite on a regular basis for a total of 7 months, once every 4 days for the first 172 days and once every other day for the final 50 days. Significant variability was observed in both continuum and emission-line fluxes. The light curves for the continuum fluxes exhibited two well-defined local minima or 'dips,' the first lasting is less than or approximately 20 days and the second is less than or approximately 4 days, with additional episodes of relatively rapid flickering of approximately the same amplitude. As in the case of NGC 5548 (the only other Seyfert galaxy that has been the subject of such an intensive, sustained monitoring effort), the largest continuum variations were seen at the shortest wavelengths, so that the continuum became 'harder' when brighter. The variations in the continuum occurred simultaneously at all wavelengths (delta(t) is less than 2 days). Generally, the amplitude of variability of the emission lines was lower than (or comparable to) that of the continuum. Apart from Mg II (which varied little) and N V (which is relatively weak and badly blended with Ly(alpha), the light curves of the emission lines are very similar to the continuum light curves, in each case with a small systematic delay or 'lag.' As for NGC 5548, the highest ionization lines seem to respond with shorter lags than the lower ionization lines. The lags found for NGC 3783 are considerably shorter than those obtained for NGC 5548, with values of (formally) approximately 0 days for He II + O III), and approximately 4 days for Ly(alpha) and C IV. The data further suggest lags of approximately 4 days for Si IV + O IV) and 8-30 days for Si III + C III). Mg II lagged the 1460 A continuum by approximately 9 days, although this result depends on the method of measuring the line flux and may in fact be due to variability of the underlying Fe II lines. Correlation analysis further shows that the power density spectrum contains substantial unresolved power over timescales of is less than or approximately 2 days, and that the character of the continuum variability may change with time