232 research outputs found
Coronal properties of active G-type stars in different evolutionary phases
We report on the analysis of XMM-Newton observations of three G-type stars in very different evolutionary phases: the "weak-line" T Tauri star HD 283572, the Zero Age Main Sequence star EK Dra and the Hertzsprung-gap giant star 31 Corn. The X-ray luminosities of the three stars are all in the range 10(30) - 10(31) erg/s. We compare the Emission Measure Distributions of these bright sources, derived from high-resolution X-ray spectra, as well as the pattern of elemental abundances vs. First Ionization Potential (FIP). The results of our analysis suggest that the coronae of these stars are very similar in terms of dominant coronal magnetic structures, in spite of differences in their evolutionary phases, surface gravities and metallicities
Essential elements nurses have to address to promote a safe discharge in paediatrics: A systematic review and narrative synthesis
Aim: The aim of the study was to synthesize the evidence on the essential elements, nurses must address when they perform therapeutic education to patients and their caregivers to promote a safe paediatric hospital-to-home discharge. Design: A systematic review and narrative synthesis. Methods: The search strategy identifies studies published between 2016 and 2023. The quality of the included studies was assessed using the Critical Appraisal Skills Programme checklists. The protocol of this review was not registered. A search of three electronic databases (PubMed, CINAHL and Web of Science) and a search in the reference lists of the included studies was conducted in February 2021 and June 2023. Results: Fifteen studies met the inclusion criteria. The essential elements identified are grouped into the following topics: emergency management, physiological needs, medical device and medications management, long-term management and short-term management. Nurses have a critical role in ensuring patient safety and quality of care, and the nurses' competence makes the difference in the discharge's related outcomes. Our results can help the nursing profession implement comprehensive discharge projects. Our results support the improvement of nurse-led paediatric discharge programmes. Nurse managers can identify the grey areas of therapeutic education provided in their units and work for their improvement. Following the implementation of therapeutic education on these topics, measuring the discharge's related outcomes could be interesting. This study addresses the problem of managing a safe and efficient nurse-led discharge in a paediatric setting. It presents evidence on the essential elements to promote a safe paediatric discharge at home. These could impact nursing practice by using them to implement project and discharge pathways. We have adhered to relevant EQUATOR guidelinesâPRISMA guidelines for reporting systematic review. No patients, service users, caregivers or public members were involved in this study due to its nature (systematic review)
Coronal properties of G-type stars in different evolutionary phases
We report on the analysis of XMM-Newton observations of three G-type stars in
very different evolutionary phases: the weak-lined T Tauri star HD 283572, the
Zero Age Main Sequence star EK Dra and the Hertzsprung-gap giant star 31 Com.
They all have high X-ray luminosity (10^31 erg/s for HD 283572 and 31 Com and
10^30 erg/s for EK Dra). We compare the Emission Measure Distributions (EMDs)
of these active coronal sources, derived from high-resolution XMM-Newton
grating spectra, as well as the pattern of elemental abundances vs. First
Ionization Potential (FIP). We also perform time-resolved spectroscopy of a
flare detected by XMM from EK Dra. We interpret the observed s as the
result of the emission of ensembles of magnetically confined loop-like
structures with different apex temperatures. Our analysis indicates that the
coronae of HD 283572 and 31 Com are very similar in terms of dominant coronal
magnetic structures, in spite of differences in the evolutionary phase, surface
gravity and metallicity. In the case of EK Dra the distribution appears to be
slightly flatter than in the previous two cases, although the peak temperature
is similar.Comment: 15 pages, 13 Postscript figures, to be published in A&
Spectral properties of X-ray bright variable sources in the Taurus Molecular Cloud
We analyze 19 bright variable X-ray sources detected in the XMM-Newton
Extended Survey of the Taurus Molecular Cloud (XEST), in order to characterize
the variations with time of their coronal properties and to derive informations
on the X-ray emitting structures. We performed time-resolved spectroscopy of
the EPIC PN and MOS spectra of the XEST sources, using a model with one or two
thermal components, and we used the time evolution of the temperatures and
emission measures during the decay phase of flares to derive the size of the
flaring loops. The light curves of the selected sources show different types of
variability: flares, long-lasting decay or rise through the whole observation,
slow modulation or complex flare-like variability. Spectral analysis shows
typical quiescent plasma temperatures of 5-10 MK and 15-35 MK; the cool
component generally remains constant, while the observed flux changes are due
to variations of the hot component. During flares the plasma reaches
temperatures up to 100 MK and luminosities up to erg s.
Loop sizes inferred from flare analysis are generally smaller than or
comparable to the stellar radius.Comment: 18 pages, 11 figures, 3 tables. Accepted by A&A, to appear in a
special section/issue dedicated to the XMM-Newton Extended Survey of the
Taurus Molecular Cloud (XEST
The X-ray activity-rotation relation of T Tauri stars in Taurus-Auriga
The Taurus-Auriga star-forming complex hosts the only population of T Tauri
stars in which an anticorrelation of X-ray activity and rotation period has
been observed. We have used XMM-Newton's European Photon Imaging Cameras to
perform the most sensitive survey to date of X-ray emission (0.3-10 keV) from
young stars in Taurus-Auriga and investigate the dependences of X-ray activity
measures -- X-ray luminosity, Lx, its ratio with the stellar luminosity,
Lx/Lstar, and the surface-averaged X-ray flux, Fxs -- on rotation period. We
tested for differences in the distributions of Lx/Lstar of fast and slow
rotators, accretors and non-accretors, and compared the dependence of Lx/Lstar
on the ratio of the rotation period and the convective turnover timescale, the
Rossby number, with that of late-type main-sequence stars. We found significant
anticorrelations of Lx and Fxs with rotation period, but these could be
explained by the typically higher stellar luminosity and effective temperature
of fast-rotators in Taurus-Auriga and a near-linear dependence of Lx on Lstar.
We found no evidence for a dependence of Lx/Lstar on rotation period, but for
accretors to have lower Lx/Lstar than non-accretors at all rotation periods.
The Rossby numbers of accretors and non-accretors were found to be the same as
those of late-type main-sequence stars showing saturated X-ray emission. We
conclude that non-accreting T Tauri stars show X-ray activity entirely
consistent with the saturated activity of late-type main-sequence stars.
Accreting T Tauri stars show lower X-ray activity, which cannot be attributed
to their slower rotation.Comment: 13 pages, 8 figures (14 eps files). Accepted by A&A, to appear in a
special section/issue dedicated to the XMM-Newton Extended Survey of the
Taurus Molecular Clou
The stellar association around Gamma Velorum and its relationship with Vela OB2
We present the results of a photometric BVI survey of 0.9 square degrees
around the Wolf-Rayet binary gamma^2 Vel and its early-type companion gamma^1
Vel. Several hundred PMS stars are identified and the youth of a subset of
these is confirmed by the presence of lithium, H-alpha emission and X-ray
activity. We show that the PMS stars are kinematically coherent and spatially
concentrated around gamma Vel. The PMS stars have similar proper motions to
gamma Vel, to main-sequence stars around gammaVel and to early-type stars of
the wider Vela OB2 association of which gamma^2 Vel is the brightest member.
The ratio of main-sequence stars to low-mass (0.1-0.6 Msun) PMS stars is
consistent with a Kroupa mass function. Main-sequence fitting to stars around
gamma Vel gives a distance modulus of 7.76+/-0.07 mag, consistent with a
similarly-determined distance for Vela OB2 and with interferometric distances
to gamma^2 Vel. High-mass stellar models indicate an age of 3-4 Myr for gamma^2
Vel, but the low-mass PMS stars have ages of ~10 Myr according to low-mass
evolutionary models and 5-10 Myr by empirically placing them in an age sequence
with other clusters based on colour-magnitude diagrams and lithium depletion.
We conclude that the low-mass PMS stars form a genuine association with gamma
Vel and that this is a subcluster within the larger Vela OB2 association. We
speculate that gamma^2 Vel formed after the low-mass stars, expelling gas,
terminating star formation and unbinding the association. The velocity
dispersion of the PMS stars is too low for this star forming event to have
produced all the stars in Vela OB2. Instead, star formation must have started
at several sites within a molecular cloud, either sequentially or,
simultaneously after some triggering event [abridged].Comment: Accepted for publication in MNRA
Total hip arthroplasty in an inveterate femoral neck fracture in a patient with congenital insensitivity to pain with anhidrosis
Congenital insensitivity to pain with anhidrosis (CIPA) is an extremely rare disorder characterized by autonomic and sensory nerves malfunction with insensitivity to both deep and superficial painful stimuli, inability to sweat and produce tears, and mild to moderate mental retardation with self-mutilating behavior. Related consequences of inveterate musculoskeletal injuries represent a major issue for these patients, since pain cannot act as a protectionmechanism. For the same reason, the patients are at risk during postoperative rehabilitation, which should be taken into account when selecting an orthopaedic implant. To our knowledge, only one case of total hip arthroplasty has been reported in the literature to date. A 21-year-old Caucasian male patient affected with CIPA arrived at our attention complaining about a functional limitation of the left hip. No history of trauma was reported. The X-rays showed an inveterate femoral neck fracture with a severe necrosis and resorption of the femoral head. We decided to performa total hip arthroplasty with a cemented stem and a cemented dual mobility cup. The postoperative course and rehabilitation were satisfactory, with excellent clinical results, measured with the Harris Hip Score at 1 year
The XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST)
(abridged:) The XMM-Newton Extended Survey of the Taurus Molecular Cloud
(XEST) surveys the most populated ~5 square degrees of the Taurus star
formation region, using the XMM-Newton X-ray observatory to study the thermal
structure, variability, and long-term evolution of hot plasma, to investigate
the magnetic dynamo, and to search for new potential members of the
association. Many targets are also studied in the optical, and high-resolution
X-ray grating spectroscopy has been obtained for selected bright sources. The
X-ray spectra have been coherently analyzed with two different thermal models
(2-component thermal model, and a continuous emission measure distribution
model). We present overall correlations with fundamental stellar parameters
that were derived from the previous literature. A few detections from Chandra
observations have been added. The present overview paper introduces the project
and provides the basic results from the X-ray analysis of all sources detected
in the XEST survey.Comprehensive tables summarize the stellar properties of all
targets surveyed. The survey goes deeper than previous X-ray surveys of Taurus
by about an order of magnitude and for the first time systematically accesses
very faint and strongly absorbed TMC objects. We find a detection rate of 85%
and 98% for classical and weak-line T Tau stars (CTTS resp. WTTS), and identify
about half of the surveyed protostars and brown dwarfs. Overall, 136 out of 169
surveyed stellar systems are detected. We describe an X-ray luminosity vs. mass
correlation, discuss the distribution of X-ray-to-bolometric luminosity ratios,
and show evidence for lower X-ray luminosities in CTTS compared to WTTS.
Detailed analysis (e.g., variability, rotation-activity relations, influence of
accretion on X-rays) will be discussed in a series of accompanying papers.Comment: 75 pg, 77 figs. Accepted by A&A, to appear in a special section/issue
dedicated to the XMM-Newton Extended Survey of the Taurus Molecular Cloud
(XEST). V2: ASCII Table 14 added. Version with higher resolution figures at
http://www.issibern.ch/teams/Taurus/papers.html or
http://www.astro.phys.ethz.ch/papers/guedel/guedel_p_nf.htm
XMM-Newton observations of the sigma Ori cluster. II. Spatial and spectral analysis of the full EPIC field
We present the results of an XMM-Newton observation of the young (~2-4 Myr)
cluster around the hot star sigma Orionis. In a previous paper we presented the
analysis of the RGS spectrum of the central hot star; here we discuss the
results of the analysis of the full EPIC field. We have detected 175 X-ray
sources, 88 of which have been identified with cluster members, including very
low-mass stars down to the substellar limit. We detected eleven new possible
candidate members from the 2MASS catalogue. We find that late-type stars have a
median log L_X/L_bol ~ -3.3, i.e. very close to the saturation limit. We
detected significant variability in ~40% of late-type members or candidates,
including 10 flaring sources; rotational modulation is detected in one K-type
star and possibly in another 3 or 4 stars. Spectral analysis of the brightest
sources shows typical quiescent temperatures in the range T_1 ~ 0.3-0.8 keV and
T_2 ~ 1-3 keV, with subsolar abundances Z ~ 0.1-0.3 Z_sun, similar to what is
found in other star-forming regions and associations. We find no significant
difference in the spectral properties of classical and weak-lined T Tauri
stars, although classical T Tauri stars tend to be less X-ray luminous than
weak-lined T Tauri stars.Comment: 20 pages, 10 figures, 6 tables. Accepted by A&
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