652 research outputs found
The 2006 hot phase of Romano's star (GR 290) in M33
Understanding the nature of the instabilities of LBVs is important to
understand the late evolutionary stages of very massive stars.
We investigate the long term, S Dor-type variability of the luminous blue
variable GR290 (Romano's star) in M33, and its 2006 minimum phase.
New spectroscopic and photometric data taken in November and December 2006
were employed in conjunction with already published data on GR290 to derive the
physical structure of GR290 in different phases and the time scale of the
variability.
We find that by the end of 2006, GR 290 had reached the deepest visual
minimum so far recorded. Its present spectrum resembles closely that of the
Of/WN9 stars, and is the hottest so far recorded in this star (and in any LBV
as well), while its visual brightness decreased by about 1.4 mag.
This first spectroscopic record of GR290 during a minimum phase confirms
that, similarly to AG Car and other LBVs, the star is subject to ample S
Dor-type variations, being hotter at minimum, suggesting that the variations
take place at constant bolometric luminosity.Comment: 4 figures, 1 table, accepted for publication in A&A Letter
The origin of the supersoft X-ray--optical/UV flux anticorrelation in the symbiotic binary AG Draconis
AG Draconis produces a strong supersoft X-ray emission.The X-ray and
optical/UV fluxes are in a strict anticorrelation throughout the active and
quiescent phases. The aim of this contribution is to identify the source of the
X-ray emission and reveal the nature of the observed flux anticorrelation. For
this purpose we model the X-ray and UV observations with XMM-Newton, far-UV
spectroscopy from FUSE, low- and high-resolution IUE spectra and
optical/near-IR spectroscopic and/or photometric observations. Our analysis
showed that the supersoft X-ray emission is produced by the white dwarf
photosphere. The X-ray and far-UV fluxes make it possible to determine its
temperature unambiguously. The supersoft X-ray--optical/UV flux anticorrelation
is caused by the variable wind from the hot star. The enhanced hot star wind
gives rise to the optical bursts by reprocessing high-energy photons from the
Lyman continuum to the optical/UV.Comment: 9 pages, 2 figures, 3 tables. Submitted to AA on 25/11/2008, revised
on 27/05/200
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
Iran and American Security Policy in the Middle East
In October 1973 the Organization of Arab Petroleum Exporting Countries (OAPEC) sent shock waves through the industrialized world when it decreased the overall production of oil and embargoed the United States, Portugal, South Africa, and the Netherlands. The impact of these developments and a subsequent quantum rise in oil prices for the Western states and Japan was immediate and far reaching. On both sides of the Atlantic and in Tokyo there were fears of recession and even depression, the possibility of millions unemployed, and of massive deficits in the balance of payments
A Flattened Protostellar Envelope in Absorption around L1157
Deep Spitzer IRAC images of L1157 reveal many of the details of the outflow
and the circumstellar environment of this Class 0 protostar. In IRAC band 4, 8
microns, there is a flattened structure seen in absorption against the
background emission. The structure is perpendicular to the outflow and is
extended to a diameter of 2 arcminutes. This structure is the first clear
detection of a flattened circumstellar envelope or pseudo-disk around a Class 0
protostar. Such a flattened morphology is an expected outcome for many collapse
theories that include magnetic fields or rotation. We construct an extinction
model for a power-law density profile, but we do not constrain the density
power-law index.Comment: ApJL accepte
Toward validating the Italian version of the “Spanish Burnout Inventory”: a preliminary study
AbstractOBJECTIVEThe aim of this study was to develop the Italian version of the Spanish Burnout Inventory (SBI) and to examine its psychometric properties within a sample of nursing staff.METHODThe study was cross-sectional and not randomized. The data were gathered using an anonymous, self-report questionnaire. The sample consisted of 391 staff nurses employed in three hospitals in the Northern Region of Italy To evaluate burnout, the SBI and the Maslach Burnout Inventory were administered.RESULTSAn Exploratory Factor Analysis showed a four-factor structure close to the expected one. All Cronbach's alpha values were satisfactory. Furthermore, correlations support the concurrent validity.CONCLUSIONOverall, the results of this study provided evidence that the SBI is an adequate instrument to study burnout in the Italian nursing sample and indicated the feeling of guilt as an important dimension to gauge the structure of this phenomenon
Toward validating the Italian version of the "Spanish Burnout Inventory": a preliminary study
OBJETIVOO objetivo deste estudo foi desenvolver a versão italiana do SBI (Spanish Burnout Inventory) e analisar as suas propriedades psicométricas numa amostra de enfermeiros.MÉTODOO estudo foi de caráter transversal, e não randomizado. Os dados foram coletados através de um questionário autopreenchido de maneira anônima. A amostra foi composta por 391 enfermeiros funcionários de três hospitais de uma região do norte da Itália. Para avaliar o burnout, utilizou-se o Spanish Burnout Inventory e o Maslach Burnout Inventory.RESULTADOSOs resultados da Análise Fatorial Exploratória mostraram uma estrutura de quatro fatores, como era esperado. Todos os valores de alfa de Cronbach foram satisfatórios. Além disso, as correlações apoiar validade concorrente.CONCLUSÃONo geral, os resultados deste estudo forneceram evidências de que o SBI é um instrumento adequado para estudar o burnout numa amostra de enfermagem italiana e indicou que os sentimentos de culpa são uma dimensão importante para avaliar a estrutura do fenômeno.OBJECTIVEThe aim of this study was to develop the Italian version of the Spanish Burnout Inventory (SBI) and to examine its psychometric properties within a sample of nursing staff.METHODThe study was cross-sectional and not randomized. The data were gathered using an anonymous, self-report questionnaire. The sample consisted of 391 staff nurses employed in three hospitals in the Northern Region of Italy To evaluate burnout, the SBI and the Maslach Burnout Inventory were administered.RESULTSAn Exploratory Factor Analysis showed a four-factor structure close to the expected one. All Cronbach's alpha values were satisfactory. Furthermore, correlations support the concurrent validity.CONCLUSIONOverall, the results of this study provided evidence that the SBI is an adequate instrument to study burnout in the Italian nursing sample and indicated the feeling of guilt as an important dimension to gauge the structure of this phenomenon.OBJETIVODesarrollar la versión italiana del Spanish Burnout Inventory (SBI) y analizar sus propiedades psicométricas en una muestra de enfermeros.MÉTODOEstudio de carácter transversal y no randomizado. Los datos fueron recogidos mediante un cuestionario autorrellenado de manera anónima. La muestra estuvo compuesta de 391 enfermeros funcionarios de tres hospitales de una zona del norte de Italia. A fin de evaluar el burnout, se empleó el Spanish Burnout Inventory y el Maslach Burnout Inventory.RESULTADOSLos resultados del Análisis Factorial Exploratorio mostraron una estructura de cuatro factores, como era esperado. Todos los valores de alfa de Cronbach fueron satisfactorios. Además, las correlaciones apoyaron la validez concurrente.CONCLUSIÓNLos resultados de este estudio proporcionaron evidencias de que el SBI es un instrumento adecuado para estudiar el burnout en una muestra de enfermería italiana y señaló que los sentimientos de culpa son una dimensión importante para evaluar la estructura del fenómeno
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