Gaia Data Release 3 Katz, D.; Sartoretti, P.; Guerrier, A. ...
Astronomy & astrophysics,
06/2023, Letnik:
674
Journal Article, Web Resource
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Context.
Gaia
Data Release 3 (
Gaia
DR3) contains the second release of the combined radial velocities. It is based on the spectra collected during the first 34 months of the nominal mission. The ...longer time baseline and the improvements of the pipeline made it possible to push the processing limit from
G
RVS
= 12 in
Gaia
DR2 to
G
RVS
= 14 mag.
Aims.
We describe the new functionalities implemented for
Gaia
DR3, the quality filters applied during processing and post-processing, and the properties and performance of the published velocities.
Methods.
For
Gaia
DR3, several functionalities were upgraded or added to the spectroscopic pipeline. The calibrations were improved in order to better model the temporal evolution of the straylight and of the instrumental point spread function (PSF). The overlapped spectra, which were mostly discarded in
Gaia
DR2, are now handled by a dedicated module. The hot star template mismatch, which prevented publication of hot stars in
Gaia
DR2, is largely mitigated now, down to
G
RVS
= 12 mag. The combined radial velocity of stars brighter than or equal to
G
RVS
= 12 mag is calculated in the same way as in
Gaia
DR2, that is, as the median of the epoch radial velocity time series. The combined radial velocity of the fainter stars is measured from the average of the cross-correlation functions.
Results.
Gaia
DR3 contains the combined radial velocities of 33 812 183 stars. With respect to
Gaia
DR2, the temperature interval has been expanded from
T
eff
∈ 3600, 6750 K to
T
eff
∈ 3100, 14 500 K for the bright stars (
G
RVS
≤ 12 mag) and 3100, 6750 K for the fainter stars. The radial velocities sample a significant part of the Milky Way: they reach a few kiloparsecs beyond the Galactic centre in the disc and up to about 10−15 kpc vertically into the inner halo. The median formal precision of the velocities is 1.3 km s
−1
at
G
RVS
= 12 and 6.4 km s
−1
at
G
RVS
= 14 mag. The velocity zeropoint exhibits a small systematic trend with magnitude that starts around
G
RVS
= 11 mag and reaches about 400 m s
−1
at
G
RVS
= 14 mag. A correction formula is provided that can be applied to the published data. The
Gaia
DR3 velocity scale agrees satisfactorily with APOGEE, GALAH, GES, and RAVE; the systematic differences mostly remain below a few hundred m s
−1
. The properties of the radial velocities are also illustrated with specific objects: open clusters, globular clusters, and the Large Magellanic Cloud. For example, the precision of the data allows mapping the line-of-sight rotational velocities of the globular cluster 47 Tuc and of the Large Magellanic Cloud.
Neurosurgical residency training paradigms have changed in response to Accreditation Council for Graduate Medical Education mandates and demands for quality patient care. Little has been done to ...assess resident education from the perspective of readiness to practice.
To assess the efficacy of resident training in preparing young neurosurgeons for practice.
In response to Resolution V-2007F of the Council of State Neurosurgical Societies, a survey was developed for neurosurgeons who applied for oral examination, Part II of the American Board of Neurological Surgery boards, in 2002 through 2007 (N = 800). The survey was constructed in "survey monkey" format and sent to 775 of 800 (97%) neurosurgeons for whom e-mail addresses were available.
The response rate was 30% (233/775). Most neurosurgeons were board certified (n = 226, 97%). General neurosurgical training was judged as adequate by a large majority (n = 188, 80%). Sixty-percent chose to pursue at least 1 additional year of fellowship training (n = 138, 60%). Surgical skills training was acceptable, but 6 skill-technique areas were reported to be inadequate (endovascular techniques, neurosurgical treatment of pain, stereotactic radiosurgery, epilepsy surgery, cranial base surgery, and stereotactic neurosurgery). Respondents also noted inadequate education in contract negotiation, practice evaluation, and management.
The study suggests that neurosurgeons believed that they were well trained in their surgical skills except for some areas of subspecialization. However, there is a significant need for improvement of resident training in the areas of socioeconomic and medicolegal education. Continued evaluation of the efficacy of neurosurgical education is important.
There is a growing belief among managers that ethnic diversity, when well managed, can provide organizations with certain competitive advantages. In a controlled experimental study comparing the ...performance on a brainstorming task between groups composed of all Anglo-Americans with groups composed of Anglo-, Asian, African and Hispanic Americans, the ideas produced by the ethnically diverse groups were judged to be of higher quality.
Context.
Fundamental atomic parameters, such as oscillator strengths, play a key role in modelling and understanding the chemical composition of stars in the Universe. Despite the significant work ...underway to produce these parameters for many astrophysically important ions, uncertainties in these parameters remain large and can propagate throughout the entire field of astronomy.
Aims.
The Belgian repository of fundamental atomic data and stellar spectra (BRASS) aims to provide the largest systematic and homogeneous quality assessment of atomic data to date in terms of wavelength, atomic and stellar parameter coverage. To prepare for it, we first compiled multiple literature occurrences of many individual atomic transitions, from several atomic databases of astrophysical interest, and assessed their agreement. In a second step synthetic spectra will be compared against extremely high-quality observed spectra, for a large number of BAFGK spectral type stars, in order to critically evaluate the atomic data of a large number of important stellar lines.
Methods.
Several atomic repositories were searched and their data retrieved and formatted in a consistent manner. Data entries from all repositories were cross-matched against our initial BRASS atomic line list to find multiple occurrences of the same transition. Where possible we used a new non-parametric cross-match depending only on electronic configurations and total angular momentum values. We also checked for duplicate entries of the same physical transition, within each retrieved repository, using the non-parametric cross-match.
Results.
We report on the number of cross-matched transitions for each repository and compare their fundamental atomic parameters. We find differences in log(
gf
) values of up to 2 dex or more. We also find and report that ~2% of our line list and Vienna atomic line database retrievals are composed of duplicate transitions. Finally we provide a number of examples of atomic spectral lines with different retrieved literature log(
gf
) values, and discuss the impact of these uncertain log(
gf
) values on quantitative spectroscopy.
Context. We still do not understand which physical mechanisms are responsible for the transport of angular momentum inside stars. The recent detection of mixed modes that contain the clear signature ...of rotation in the spectra of Kepler subgiants and red giants gives us the opportunity to make progress on this question. Aims. Our aim is to probe the radial dependence of the rotation profiles for a sample of Kepler targets. For this purpose, subgiants and early red giants are particularly interesting targets because their rotational splittings are more sensitive to the rotation outside the deeper core than is the case for their more evolved counterparts. Methods. We first extracted the rotational splittings and frequencies of the modes for six young Kepler red giants. We then performed a seismic modeling of these stars using the evolutionary codes Cesam2k and astec. By using the observed splittings and the rotational kernels of the optimal models, we inverted the internal rotation profiles of the six stars. Results. We obtain estimates of the core rotation rates for these stars, and upper limits to the rotation in their convective envelope. We show that the rotation contrast between the core and the envelope increases during the subgiant branch. Our results also suggest that the core of subgiants spins up with time, while their envelope spins down. For two of the stars, we show that a discontinuous rotation profile with a deep discontinuity reproduces the observed splittings significantly better than a smooth rotation profile. Interestingly, the depths that are found to be most probable for the discontinuities roughly coincide with the location of the H-burning shell, which separates the layers that contract from those that expand. Conclusions. We characterized the differential rotation pattern of six young giants with a range of metallicities, and with both radiative and convective cores on the main sequence. This will bring observational constraints to the scenarios of angular momentum transport in stars. Moreover, if the existence of sharp gradients in the rotation profiles of young red giants is confirmed, it is expected to help in distinguishing between the physical processes that could transport angular momentum in the subgiant and red giant branches.
Issue: Current medical school curricula emphasize general practice principles, and this has led predictably to increasingly limited exposure to subspecialties, including neurosurgery. However, a ...significant amount of neurosurgical disease and/or emergencies present in primary care settings or emergency rooms. In light of an already acknowledged shortage of neurosurgery providers, this means that general practitioners should be well educated and prepared to diagnose and manage neurosurgical disease. Considering the devastating consequences of a missed or delayed neurosurgical diagnosis, limiting future physicians' exposure to the field of neurosurgery is not in the best interests of the patient. Evidence: In this article, the authors review and discuss the results of several studies investigating the prevalence, presentation, diagnosis, and management of neurosurgical disease in emergency and general practice settings. They then discuss the current status of neurosurgical education in medical schools, both from the educators' and students' perspectives, and how this status might impact patient care. Finally, they offer suggestions for the improvement of neurosurgical education during medical school. Implications: Despite being considered highly subspecialized, neurosurgical diagnosis and care is a field in which all physicians should receive proper education and training. To properly serve patients and produce competent physicians, steps should be taken to re-emphasize the importance of neurosurgical education for medical students.
Abstract
BACKGROUND:
Although the long-term outcomes for spinal cord stimulation (SCS) have been reported, long-term outcomes of patients who underwent revisions of the SCS with paddle leads are ...lacking.
OBJECTIVE:
To report the long-term outcomes of 39 patients who had percutaneous SCS revised with a new paddle lead.
METHODS:
Baseline and follow-up mail-in questionnaires assessed pain and disability levels with numerical rating scales, somatotopical overlap between SCS-related paresthesias and areas of chronic pain, and overall satisfaction. Analysis was performed with regard to age, sex, diagnosis, duration of disease, number of surgical revisions, complications, and interval between surgeries.
RESULTS:
After surgical revision, 20 patients (50%) had at least a 3-point reduction in the numerical rating scale. Greater pain reduction was correlated with better coverage (P = .001). Coverage area was greater in patients with a single revision than in patients with multiple revisions (P = .01). Good satisfaction was reported by 25 patients (62.5%) who indicated that they would undergo the procedure again in order to achieve the same results. These patients had significantly greater pain reduction (P = .001) and better coverage (P = .002) than patients who reported otherwise. No other major complication occurred.
CONCLUSION:
Revision of percutaneous SCS systems with implantation of a new paddle lead is safe and more effective in patients who have undergone not more than 1 prior revision.
Aims.
We performed a spectral fitting for a set of O-type stars based on self-consistent wind solutions, which provide mass-loss rate and velocity profiles directly derived from the initial stellar ...parameters. The great advantage of this self-consistent spectral fitting is therefore the reduction of the number of free parameters to be tuned.
Methods.
Self-consistent values for the line-force parameters (
k
,
α
,
δ
)
sc
and subsequently for the mass-loss rate,
M
sc
, and terminal velocity, υ
∞‚sc
, are provided by the m-CAK prescription introduced in Paper I, which is updated in this work with improvements such as a temperature structure
T
(
r
) for the wind that are self-consistently evaluated from the line-acceleration. Synthetic spectra were calculated using the radiative transfer code FASTWIND, replacing the classical
β
-law for our new calculated velocity profiles
v
(
r
) and therefore making clumping the only free parameter for the stellar wind.
Results.
We found that self-consistent m-CAK solutions provide values for theoretical mass-loss rates of the order of the most recent predictions of other studies. From here, we generate synthetic spectra with self-consistent hydrodynamics to fit and obtain a new set of stellar and wind parameters for our sample of O-type stars (HD 192639, 9 Sge, HD 57682, HD 218915, HD 195592, and HD 210809), whose spectra were taken with the high-resolution echelle spectrograph H
ERMES
(
R
= 85 000). We find a satisfactory global fit for our observations, with a good accuracy for photospheric He I and He II lines and a quite acceptable fit for H lines. Although this self-consistent spectral analysis is currently constrained in the optical wavelength range alone, this is an important step towards the determination of stellar and wind parameters without using a
β
-law. Based on the variance of the line-force parameters, we establish that our method is valid for O-type stars with
T
eff
≥ 30 kK and log
g
≥ 3.2. Given these results, we expect that the values introduced here are helpful for future studies of the stars constituting this sample, together with the prospect that the m-CAK self-consistent prescription may be extended to numerous studies of massive stars in the future.
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