817 research outputs found
Non-LTE Abundances of Magnesium, Aluminum and Sulfur in OB Stars Near the Solar Circle
Non-LTE abundances of magnesium, aluminum and sulfur are derived for a sample
of 23 low-v \sin i stars belonging to six northern OB associations of the
Galactic disk within 1 kpc of the Sun. The abundances are obtained from the
fitting of synthetic line profiles to high resolution spectra. A comparison of
our results with HII region abundances indicates good agreement for sulfur
while the cepheid abundances are higher. The derived abundances of Mg show good
overlap with the cepheid results. The aluminum abundances for OB stars are
significantly below the cepheid values. But, the OB star results show a
dependence with effective temperature and need further investigation. The high
Al abundances in the cepheids could be the result of mixing. A discussion of
the oxygen abundance in objects near the solar circle suggests that the current
mean galactic oxygen abundance in this region is 8.6-8.7 and in agreement with
the recently revised oxygen abundance in the solar photosphere. Meaningful
comparisons of the absolute S, Al and Mg abundances in OB stars with the Sun
must await a reinvestigation of these elements, as well as the meteoritic
reference element Si, with 3D hydrodynamical model atmospheres for the Sun. No
abundance gradients are found within the limited range in galactocentric
distances in the present study. Such variations would be expected only if there
were large metallicity gradients in the disk.Comment: 3 figures, accepted for publication in A&A, needs aa.st
Regarding the Precision of an Estimate of the Amount of Rock Lobster Poaching Obtainable using the Amahlo approach
An illustrative computation is developed for the precision of an estimate of the amount of rock lobster poaching using the Amahlo approach. Using initial coarse estimates provided by Amahlo of typical numbers poached per day and the number of units (vessels, etc.), a CV of about 15% is indicated. However care should be taken in interpreting this in the light of the difficulties of evaluating Amahlo’s data gathering approaches in a manner that readily provides the values needed to estimate the precision of a final estimate of rock lobster taken annually by poachers
Cardiac output measurement is feasible in the presence of left-to-right shunt with ultrasound dilution method: a validation study in lambs
A New Formation Channel for Double Neutron Stars Without Recycling: Implications for Gravitational Wave Detection
We report on a new evolutionary path leading to the formation of close double
neutron stars (NS), with the unique characteristic that none of the two NS ever
had the chance to be recycled by accretion. The existence of this channel stems
from the evolution of helium-rich stars (cores of massive NS progenitors),
which has been neglected in most previous studies of double compact object
formation. We find that these non-recycled NS-NS binaries are formed from bare
carbon-oxygen cores in tight orbits, with formation rates comparable to or
maybe even higher than those of recycled NS-NS binaries. On the other hand,
their detection probability as binary pulsars is greatly reduced (by about
1000) relative to recycled pulsars, because of their short lifetimes. We
conclude that, in the context of gravitational-wave detection of NS-NS inspiral
events, this new type of binaries calls for an increase of the rate estimates
derived from the observed NS-NS with recycled pulsars, typically by factors of
1.5-3 or even higher.Comment: Accepted for publication in ApJ Letters; 5 pages, 1 figure, 2 tables.
Two new paragraphs and one formula adde
Use of neoadjuvant chemotherapy in locally advanced breast cancer in the Netherlands
Use of neoadjuvant chemotherapy in locally advanced breast cancer in the Netherlands P.E.R. Spronk1, A.C.M. Van Bommel1, S. Siesling2,3, M.J.T. Baas- Vrancken Peeters4, C.H. Smorenburg5. 1Leiden University Medical Centre, Surgery, Leiden, Netherlands; 2Comprehensive Cancer Centre the Netherlands IKNL, Epidemiology, Utrecht, Netherlands; 3University of Twente, MIRA Biomedical science and Technical Medicine, Twente, Netherlands; 4Netherlands Cancer Institute/Antoni van Leeuwenhoek, Surgery, Amsterdam, Netherlands; 5Netherlands Cancer Institute/Antoni van Leeuwenhoek, Medical Oncology, Amsterdam, Netherlands Background: Neoadjuvant chemotherapy (NAC) is the treatment of choice for patients with locally advanced breast cancer (LABC). The aim of this study is to examine the use of NAC for LABC in all Dutch hospitals participating in breast cancer care and to assess what patient, tumour and hospital characteristics influence its use. Material and Methods: Data were derived from the national multidisciplinary NABON Breast Cancer Audit (NBCA), regarding all women aged >18 years and newly diagnosed with LABC from January 2011 to September 2013. Multivariable logistic regression was used to assess the association between the use of NAC and patient, tumour and hospital related factors. Results: Of 1419 woman diagnosed with LABC, 70% were treated with NAC. This percentage varied from 12.5% to 90% between hospitals and did not increase over time. Factors associated with the use of NAC included young age, large tumour size, more advanced nodal disease and triple negative or hormone-receptor negative tumours. Also patients treated in hospitals with a multidisciplinary preoperative work-up and participation in neoadjuvant studies were more likely to receive NAC. However, considerable variation between hospitals remained after casemix correction. Table 1. Multivariable odds ratios (ORs) for receipt of NAC among 1419 stage III patients 2011 through 2013 OR 95% CI P-value Age 0.000 5 cm 5.68 2.34−13.79 Clinical nodal status 0.000 cNx/N0 ref. cN1 1.32 0.86−2.04 cN2 2.93 1.18−7.29 cN3 10.28 4.18−25.25 Receptor status 0.000 Triple negative 2.35 1.40−3.93 HR−, Her2+ 3.37 1.67−6.78 HR+, Her2+ 0.91 0.51−1.60 HR+, Her2− ref. Type of surgery 0.026 Breast conservation therapy 2.05 1.09−3.84 Mastectomy ref. Multidisciplinary team 0.021 Yes 1.98 1.11−3.53 No ref. Type of hospital 0.569 General 1.20 0.73−1.98 Top clinical ref. Academic 1.50 0.64−3.47 Hospital surgical volume 0.729 200 1.27 0.70−2.31 Study participation 0.005 Yes 1.80 1.20−2.70 No ref. Conclusions: There is considerable variation in the use of NAC for LABC in the Netherlands. Although various patient, tumor and institutional factors are associated with the use of NAC in LABC, these can only explain part of the observed variation in treatment patterns between hospitals
Presupernova Evolution of Differentially Rotating Massive Stars Including Magnetic Fields
As a massive star evolves through multiple stages of nuclear burning on its
way to becoming a supernova, a complex, differentially rotating structure is
set up. Angular momentum is transported by a variety of classic instabilities,
and also by magnetic torques from fields generated by the differential
rotation. We present the first stellar evolution calculations to follow the
evolution of rotating massive stars including, at least approximately, all
these effects, magnetic and non-magnetic, from the zero-age main sequence until
the onset of iron-core collapse. The evolution and action of the magnetic
fields is as described by Spruit 2002 and a range of uncertain parameters is
explored. In general, we find that magnetic torques decrease the final rotation
rate of the collapsing iron core by about a factor of 30 to 50 when compared
with the non-magnetic counterparts. Angular momentum in that part of the
presupernova star destined to become a neutron star is an increasing function
of main sequence mass. That is, pulsars derived from more massive stars will
rotate faster and rotation will play a more dominant role in the star's
explosion. The final angular momentum of the core is determined - to within a
factor of two - by the time the star ignites carbon burning. For the lighter
stars studied, around 15 solar masses, we predict pulsar periods at birth near
15 ms, though a factor of two range is easily tolerated by the uncertainties.
Several mechanisms for additional braking in a young neutron star, especially
by fall back, are also explored.Comment: 32 pages, 3 figures (8 eps files), submitted to Ap
Measurement of cardiac output using the transpulmonary thermodilution method in the presence of high extravascular lung water in a pediatric animal model
Recommended from our members
Producing Crack-Free, High Density M2 HSS Parts by Selective Laser Melting: Pre-Heating the Baseplate
Cracks and delamination, resulting from residual stresses are a barrier in the world of Additive
Manufacturing and Selective Laser Melting (SLM) that prohibits the use of many metals in this field. By preheating the baseplate, thermal gradients are lowered and stresses can be reduced. In this work, some initial tests
were performed with M2 Tool Steel. Results show that pre-heating enables the production of dense M2 parts.
The influence of pre-heating on density and mechanical and physical properties is investigated. The paper
shows many promising results for the production of SLM parts in materials that are very sensitive to crack
formation and delamination. When using a pre-heating of 200°C, crack-free parts were produced with a relative
density of 99.8%.Mechanical Engineerin
Let's talk about sex! Why should healthcare professionals address sexual distress in breast cancer patients and survivors?
Purpose: Sexual distress impacts the quality of life (QoL) of breast cancer patients but is often overlooked in standard care pathways. This study evaluated the prevalence and factors of sexual distress among Dutch breast cancer patients, compared them to the general population, and explored how sexual distress is discussed in clinical settings from the perspectives of patients and healthcare professionals (HCPs). Methods: Questionnaires containing the Female Sexual Distress Scale (FSDS) and demographic variables were distributed to women with breast cancer. The effect of breast cancer on sexual distress was assessed with a Mann-Whitney U test. Multivariable linear regression was used to analyze variables associated with FSDS. The Sexuality Attitudes and Beliefs Survey (SABS) was sent to HCPs. Results: Breast cancer patients reported significantly higher sexual distress compared to a Dutch non-breast cancer cohort, respectively 16.38 (SD 11.81) and 23.35 (SD 11.39). Factors associated with higher sexual distress were psychological comorbidities, the body image scale, and being diagnosed >10 years ago. Sexual distress was not discussed as often as patients needed. Barriers to addressing sexual distress were time constraints, HCPs’ confidence in their ability to address sexual distress, and uncertainty about who is responsible for initiation. Conclusions: Breast cancer patients showed significantly higher sexual distress compared to the Dutch population. However, it was not frequently addressed in the consultation room. While some barriers have been identified, this study highlights the importance of further exploring obstacles to integrating discussions about sexual distress into routine care to improve QoL of breast cancer patients.</p
The Projected Rotational Velocity Distribution of a Sample of OB stars from a Calibration based on Synthetic He I lines
We derive projected rotational velocities (vsini) for a sample of 156
Galactic OB star members of 35 clusters, HII regions, and associations. The HeI
lines at 4026, 4388, and 4471A were analyzed in order to define
a calibration of the synthetic HeI full-widths at half maximum versus stellar
vsini. A grid of synthetic spectra of HeI line profiles was calculated in
non-LTE using an extensive helium model atom and updated atomic data. The
vsini's for all stars were derived using the He I FWHM calibrations but also,
for those target stars with relatively sharp lines, vsini values were obtained
from best fit synthetic spectra of up to 40 lines of CII, NII, OII, AlIII,
MgII, SiIII, and SIII. This calibration is a useful and efficient tool for
estimating the projected rotational velocities of O9-B5 main-sequence stars.
The distribution of vsini for an unbiased sample of early B stars in the
unbound association Cep OB2 is consistent with the distribution reported
elsewhere for other unbound associations.Comment: Accepted for publication in The Astronomical Journa
- …