bluuebunny/crossref_metadata_2025_split huggingface dataset:
The lasting impact of virtual interviews on surgical fellowship applicants
Authors: Becker Ellen R. , Xu Catherine T. , Pratt Catherine G. , Whitrock Jenna N. , Frasier Lane L. , Van Haren Robert M. , Quillin Ralph C. 
Published: August 2024

Abstract
Purpose
Surgical fellowship interviews shifted to a virtual platform in 2020 due to the COVID-19 pandemic. While virtual interviews provide convenience, they also pose difficulties for programs and raise potential barriers for applicants. This study compares in-person to virtual interviews and characterizes the impact on programs and applicants.

Methods
In-person (2007–2019) and virtual (2020–2022) fellowship application data were extracted from publicly available NRMP Specialties Matching Service data. Fellowship programs included surgical critical care, surgical oncology, colorectal, pediatric, thoracic, and vascular surgery. Competitiveness was assessed using a validated normalized competitiveness index (NCI).

Results
Since virtual interviews, rankings per applicant, a surrogate for program interview workload, increased for all fellowships except pediatric surgery. The most competitive subspecialties now include colorectal, pediatric, and thoracic surgery. For non-US MDs in these subspecialties, applicants per position decreased (pediatric), match rate decreased (thoracic), and NCI increased (thoracic) under virtual interviewing. However, for the least competitive subspecialties, non-US MDs had increased rankings per applicant (critical care and vascular), increased match rate (critical care and surgical oncology), and decreased NCI (surgical oncology) with virtual interviewing.

Conclusions
Since the virtual platform was implemented, applicants have interviewed at and ranked more programs, subsequently increasing program workload. While this is positive for many applicants, a differential pattern of securing a fellowship emerged for non-US MD applicants. This finding is important for fellowship program directors to consider and ensure non-US MD applicants are not marginalized with the virtual platform.

Level of Evidence
III
Improving Access Trust in Healthcare Through Multimodal Deep Learning for Affective Computing
Authors: Sakthidevi I. , Fathima G. 
Published: August 2024

AbstractIn healthcare domain, access trust is of prime importance paramount to ensure effective delivery of medical services. It also fosters positive patient-provider relationships. With the advancement of technology, affective computing has emerged as a promising approach to enhance access trust. It enables systems to understand and respond to human emotions. The research work investigates the application of multimodal deep learning techniques in affective computing to improve access trust in healthcare environment. A novel algorithm, "Belief-Emo-Fusion," is proposed, aiming to enhance the understanding and interpretation of emotions in healthcare. The research conducts a comprehensive simulation analysis, comparing the performance of Belief-Emo-Fusion with existing algorithms using simulation metrics: modal accuracy, ınference time, and F1-score. The study emphasizes the importance of emotion recognition and understanding in healthcare settings. The work highlights the role of deep learning models in facilitating empathetic and emotionally intelligent technologies. By addressing the challenges associated with affective computing, the proposed approach contributes to the development of more effective and reliable healthcare systems. The findings offer valuable insights for researchers and practitioners seeking to leverage deep learning techniques for enhancing trust and communication in healthcare environments.
Violent Competition and Terrorist Restraint
Authors: Polo Sara M.T. , Welsh Blair 
Published: August 2024

AbstractA large literature has argued that domestic competition increases a militant organization's use and severity of terrorism to differentiate their “brand” and “outbid” other organizations. However, most empirical analyses infer such competition from the quantity of groups present in a geographic area. This approach neglects specific group relationships, such as cooperation, rhetorical or violent rivalry, or peaceful coexistence. We introduce a behavioral measure of group competition and argue that variation in the quality, rather than the quantity, of competition affects the violence profile of militant groups in unexpected ways. Violent competition, where militants attack one another, imposes significant constraints on group resources and increases groups’ dependence on civilian support, which exacerbates the costs of a popular backlash against brutality. Moreover, violent competition effectively substitutes for crowding out rivals via outbidding. As competition becomes extreme, we posit that groups increasingly opt for a strategy of terrorist restraint and reduce the share of high-profile attacks on soft civilian targets. We test this argument at the macro and micro levels with cross-national data on 290 organizations in civil war (1970–2018) and granular data on the subnational targeting strategy of the Islamic State in Syria (2013–2018). Both analyses provide robust support for our argument. The findings shed light on the strategic limitations of outbidding and provide important insights for research and policy.
One step closer to the First Stars: +150 OB stars in the metal-poor galaxy Sextans A
Authors: Lorenzo Marta , Garcia Miriam , Najarro Francisco 
Published: August 2024

AbstractLocal Group (LG) very metal-poor massive stars are the best proxy for the First Stars of the Universe, fundamental to model the early evolution of the first galaxies, and key to unravelling new evolutionary pathways restricted to low metallicities, such as chemically homogeneous evolution. Yet, due to the great leap in distance required to reach metal-poor galaxies of the LG and vicinity, no comprehensive spectroscopic studies have been carried out at sub-$$$$ metallicities so far.We focus on the massive star population of the 1/10Ȯ galaxy Sextans A. After five observing campaigns at the 10.4-m Gran Telescopio Canarias (GTC), we have assembled a spectroscopic catalogue of more than 150 OB stars. This catalogue will be fundamental to test stellar evolution at very low metallicity, to detect the first binary systems at 1/10Ȯ and to unveil the most recent star formation history of this galaxy.
Luminous blue variables and B[e] supergiants
Authors: Mehner Andrea 
Published: August 2024

AbstractLuminous blue variables (LBVs) and B[e] supergiants (B[e]SGs) are some of the most massive stars that display extreme and puzzling behavior. Their rarity indicates that they belong to short evolutionary phases or short-lived phenomena in the post-main sequence evolution of massive stars. However, their strong mass loss and episodic mass eruptions may be crucially impacting massive star evolution. LBVs are a group of evolved massive stars that exhibit irregular variability and eruptive mass loss. Various subtypes, including S Doradus variables, giant eruptions, and pre-supernova outbursts, exist. The physical cause of the LBV phenomenon remains heavily debated. B[e]SGs have strong forbidden line emission and infrared excess from dust that are thought to arise in a circumstellar disk or torus. The formation mechanism of their disk-like structures is yet to be settled. The evolutionary phases of LBVs and B[e]SGs and their connection to other evolved massive stars are important unanswered questions in massive star evolution.
On the elusive detection of O-type stars close to the ZAMS: the empirical birthline of massive stars
Authors: Holgado G. , Simón-Díaz S. , Haemmerlé L. 
Published: August 2024

AbstractIn this contribution we present the results from a1 homogeneous quantitative spectroscopic analysis of ∼400 Galactic O-type stars targeted by the IACOB and OWN surveys. The ultimate objective is to perform a modern reassessment of one of the long-standing problems in the field of massive stars: the elusive detection of mid O-type stars close to the “canonical” theoretical ZAMS. We first provide statistically significant evidence of the existence of a clear lack of stars in our sample populating the region of the spectroscopic HR diagram approximately delimited by the theoretical ZAMS, the ∼ 40 and ∼ 70 M⊙ single evolutionary tracks and the 2 Myr isochrone. We then evaluate if this empirical result could be a result of possible limitations of our analysis strategy and/or the existence of potential observational biases affecting the compiled sample. Once both explanations are investigated, we evaluate the possibility that a modification of the efficiency of mass accretion during the star formation process could lead to a new (corrected) theoretical ZAMS in better accordance with our empirical results.
Low-frequency radio view of a fast-blue optical transient - AT 2018cow
Authors: Nayana A. J. , Chandra Poonam 
Published: August 2024

AbstractWe present low-frequency (0.40 – 1.25 GHz) radio observations and modeling of a Fast Blue Optical Transient (FBOT), AT2018cow [Nayana & Chandra(2021)]. Our data are best modeled as an inhomogeneous synchrotron emitting region expanding into an ionized circumstellar medium. We estimate the mass-loss rate of the progenitor star and shock parameters at multiple epochs post-explosion and find that the progenitor has gone through an enhanced phase of mass-loss close to its end-of-life.
Constraining the dynamical mass of the massive binary 9 Sagittarii
Authors: Fabry Matthias , Hawcroft Calum , Frost Abigail J. , Mahy Laurent , Marchant Pablo , Le Bouquin Jean-Baptiste , Sana Hugues 
Published: August 2024

AbstractEspecially in the upper Hertzsprung-Russell diagram, where stellar physics is least understood, obtaining model independent masses is of great value. Spectroscopic binaries that are also resolved astrometrically are an excellent alternative to eclipsing double-lined spectroscopic binaries where dynamical masses can be measured. 9 Sgr is such a massive binary. However, its characterization is troubled by conflicting conclusions from the spectroscopic analysis on the one hand and the interferometric one on the other hand. In this work, we attempt to resolve this tension by applying a novel approach to spectral disentangling of the spectroscopic data to constrain better the mass of 9 Sgr.
The enigmatic winds of Wolf-Rayet stars: Results from dynamically consistent atmosphere modelling
Authors: Sander Andreas A. C. 
Published: August 2024

AbstractLine-driven stellar winds are ubiquitous among hot massive stars. In some cases they can become so strong, that the whole star is cloaked by an optically thick wind. The strong outflow gives rise to large emission lines, defining the class of so-called Wolf-Rayet (WR) stars. While being major players in the evolution of massive stars, the formation of heavy black holes, and the distribution of elements, the occurrence and nature of WR winds is still quite enigmatic.A promising instrument towards a better theoretical understanding are stellar atmospheres allowing for a consistent inclusion of the hydrodynamics. By coupling stellar and wind parameters and the inclusion of a detailed non-LTE radiative transfer, they allow us to go beneath the observable layers and study the onset of WR-type winds. Establishing larger sets of models, we were able to make ground-breaking progress by identifying trends with mass and metallicity that deviate significantly from present empirical descriptions. Our modelling efforts reveal a complex picture for WR-type winds with strong, non-linear dependencies. Besides covering metallicity and mass, we further identify surface hydrogen as an important ingredient to retain WR-type mass loss at lower metallicity. Here, we present a summary of recent insights on the nature and onset of WR-type winds in massive stars including the consequences for stellar evolution, remaining open questions, and current efforts to overcome them.
Dissecting the very metal-poor galaxy SBS0335-052E with MUSE: massive stars vs. nebular HeII emission
Authors: Kehrig C. , Vílchez J. M. , Guerrero M. A. , Iglesias-Páramo J. , Hunt L. K. , Duarte Puertas S. , Ramos-Larios G. 
Published: August 2024

AbstractNebular Heii emission implies the presence of energetic photons (E≽54 eV). Despite the great deal of effort dedicated to understanding Heii ionization, its origin has remained mysterious, particularly in metal-deficient star-forming galaxies. Unfolding Heii-emitting, metal-poor starbursts at z∼0 can yield insight into the powerful ionization processes occurring in the primordial universe. Here we present a study on the origin of the extended nebular Heii emission in SBS 0335-052E, one of the most metal-poor (Z ∼ 3% Z⊙ Heii-emitter starbursts known locally. Based on optical VLT/MUSE spectroscopic and Chandra X-ray observations, and current stellar models we found that the Heii-ionization budget of SBS 0335-052E can only be produced by peculiar, nearly metal-free ionizing stars (called here “PopIII-like” stars) with a top-heavy initial mass function. This result is in line with recent simulations for PopIII star formation down to z=0.
Spins of stripped B stars support magnetic internal angular momentum transport
Authors: Schürmann Christoph , Langer Norbert , Xu Xiao-Tian , Wang Chen 
Published: August 2024

AbstractThe galactic binary star LB-1 contains a recently stripped B-type star. Comparing its properties to detailed binary star models shows that tidal braking and magnetic torques lead to low surface rotational velocities in the stripped donors after Roche-lobe overﬃow. Models without magnetic torques cannot reproduce the observed low surface rotation.
First results of a magnetic survey of classical Cepheids
Authors: Barron James A. , Wade Gregg A. , Folsom Colin P. , Kochukhov Oleg 
Published: August 2024

AbstractWe report recent ESPaDOnS and HARPSpol spectropolarimetric observations from our ongoing magnetic survey of the brightest twenty-five classical Cepheids. Stokes V magnetic signatures are detected in eight of fifteen targets observed to date. The Stokes V profiles show a diversity of morphologies with weak associated longitudinal field measurements of order 1 G. Many of the Stokes V profiles are difficult to interpret in the context of the normal Zeeman effect. They consist of approximately unipolar single or double lobe(s) of positive or negative circular polarization. We hypothesize that these unusual signatures are due to the Zeeman effect modified by atmospheric velocity or magnetic field gradients. In contrast, the Stokes V profiles of Polaris and MY Pup appear qualitatively similar to the complex magnetic signatures of non-pulsating cool supergiants, possibly due to the low pulsation amplitudes of these two stars.
Alicante Survey of Massive Stars in H ii regions (A-SMASHER)
Authors: Marco A. , Negueruela I. , de la Fuente D. , Patrick L. R. , Herrero A. , Eikenberry S. S. 
Published: August 2024

AbstractThe aim of this survey is the homogeneous characterization of a large sample of H ii regions with active star formation in order to detect observational trends supporting the two main models of massive star formation.
The multiplicity of Galactic Wolf-Rayet stars
Authors: Dsilva Karan , Shenar Tomer , Sana Hugues , Marchant Pablo 
Published: August 2024

AbstractWe present the results of a magnitude-limited spectroscopic survey of Galactic Wolf-Rayet stars with the HERMES spectrograph mounted on the Mercator telescope. Using cross-correlation to measure radial velocities, we measured the observed binary fractions of the Galactic carbon- (WC) and nitrogen-rich (WN) Wolf-Rayet stars to be and . We used Monte-Carlo simulations with a Bayesian framework to derive the intrinsic multiplicity properties and found and . We find that the majority of WN binaries reside in short-period systems, similar to O stars. However, the orbital period distribution of the Galactic WC population peaks at 5000 d, a discrepancy that challenges our current understanding of binary evolution in Wolf-Rayet stars.
Analytic, Turbulent Pressure Driven Mass Loss from Red Supergiants
Authors: Kee N. Dylan ,   the MAESTRO Project
Published: August 2024

AbstractDespite the important role mass loss in the red supergiant phase plays in controlling stellar evolution and massive stars’ final supernova fates, a theoretical explanation of the mechanism driving this mass loss has been elusive. In this contribution we present a recent breakthrough [Kee et∼al., 2021] showing that turbulent pressure alone is sufficient to markedly extend the atmospheres of red supergiants and allow a wind to be launched. The resulting theory provides a fully analytic prescription for red supergiant mass-loss rates. Moreover, the theoretical mass-loss rates computed from observationally inferred turbulent velocities are in overall good agreement with observationally inferred red supergiant mass loss. A particularly interesting aspect of this theory is that it is not sensitive to metallicity, providing important implications for stellar evolution and the so-called “red-supergiant problem” for supernova progenitors in various environments.
ULLYSES and Complementary Surveys of Massive Stars in the Magellanic Clouds
Authors: Crowther Paul A. 
Published: August 2024

AbstractAn overview is provided of the scientific goals of the Magellanic Cloud component of the STScI Directors Discretionary UV initiative ULLYSES, together with the complementary spectroscopic survey XShootU (VLT/Xshooter) and other ancillary datasets. Together, ULLYSES and XShootU permit the first comprehensive, homogeneous study of wind densities and velocities in metal-poor massive stars, plus UV/optical spectroscopic libraries for population synthesis models and a large number of interstellar sight-lines towards the Magellanic Clouds.
Constraining massive star mass loss through supernova radio properties
Authors: Moriya Takashi 
Published: August 2024

AbstractSupernova properties in radio strongly depend on their circumstellar environment and they are an important probe to investigate the mass loss of supernova progenitors. Recently, core-collapse supernova observations in radio have been assembled and the rise time and peak luminosity distribution of core-collapse supernovae in radio has been obtained. In this talk, we will discuss the constraints on the mass-loss prescriptions of red supergiants obtained from the assembled radio properties of Type II supernovae. We take a couple of mass-loss prescriptions for red supergiants, calculate the rise time and peak luminosity distribution based on them, and compare the results with the observed distribution. We found that the widely spread radio rise time and peak luminosity distribution of Type II supernovae can only be explained by mass-loss prescriptions having strong dependence on the luminosity. Red supergiant mass-loss prescriptions should have steep luminosity dependence in the supernova progenitor range.
The largest and most ambitious quantitative spectroscopic analysis of B-type supergiants in the Milky Way
Authors: de Burgos Abel , Simon-Díaz Sergio , Urbaneja Miguel A. 
Published: August 2024

AbstractEmpirical constraints are master keys for testing theoretical evolutionary model predictions. In massive stars, the region in the Hertzsprung-Russell diagram (HRD) in which the Blue Supergiants (BSGs) are located sets several important constraints to the models, and in particular to the theoretical end of the main sequence (MS). So far, we are missing from a full quantitative spectroscopic analysis (QSA) of a sample of BSGs large enough to be statistically significant and without observational biases. We present results from a QSA of a sample of ∼700 Galactic BSGs for which we have high-resolution multi-epoch optical spectra.
NGC 3125-A1 revisited at higher spectral resolution with COS G160M
Authors: Wofford A. , Sixtos A. , Smith L. , Charlot S. , Bruzual G. 
Published: August 2024

AbstractSuper star cluster (SSC) A1 in starburst galaxy NGC 3125 has the strongest broad He II λ1640 emission line ever observed in the nearby Universe and constitutes an important template for interpreting observations of galaxies that are located out to a redshift of z∼3. We use observations of SSC A1 obtained with the Cosmic Origins Spectrograph (COS) on board of the Hubble Space Telescope (HST) in order to check if there is a contribution of nebular emission to the He II line. In addition, we compare the COS G130M + G160M observations of A1 (1150 – 1750∘A) to the latest Charlot & Bruzual population synthesis models, which account for Very Massive Stars (VMS) of up to 300 Mȯ. A model with Z = 0.008 and age = 2.4 Myr provides a very reasonable fit to the C III λ1175, N V λ1240, C IV λ1550, He II λ1640, and N IV λ1718 stellar-wind features, although the O V λ1371 line is not well reproduced. Overall, our results show the great improvement of stellar evolution and population synthesis models over the past decade, and in particular, the improved formulation of stellar mass loss rates.
Variable mass loss on 100 yr timescales from massive yellow hypergiants
Authors: Oudmaijer René D. , Koumpia Evgenia 
Published: August 2024

AbstractThis contribution presents new results on two members of the class of post-Red Supergiants, IRAS 17163-3907, the central star of the Fried Egg nebula and IRC +10420. New optical spectra in the blue spectral range confirm their spectral type to be of A-supergiant class. Our VLTI/GRAVITY K-band interferometry reveals that the neutral Na i 2.2 μm line emitting region is smaller than that of the hydrogen Brγ emission. This can be explained with the hydrogen emission the result of collisional excitation populating the higher levels in a neutral region instead them being populated through recombination in an ionised environment as mostly inferred in stellar winds. Finally, the central star of the Fried Egg nebula, has undergone 3 distinct mass loss episodes over the last hundreds of years. As it is likely that at least the last mass loss event occurred when the star was already a Yellow Hypergiant and not a Red Supergiant, we put forward the bi-stability mechanism as explanation for the mass loss.
Supplying angular momentum to the jittering jets explosion mechanism using convection in inner star layers
Authors: Shishkin Dmitry 
Published: August 2024

AbstractThe jittering jets explosion mechanism of core collapse supernovae proposes that stochastic convective motion, amplified by instabilities, results in intermittent accretion disk that launches jittering jets that explode the star. We conduct one-dimensional simulations of a wide range of stellar masses and show that the convective motion in the pre-collapse stellar core, when scaled to corresponding three-dimensional simulations, supply sufficient angular momentum fluctuation to form the intermittent accretion disk the launches the jittering jets. The resulting neutron star masses are consistent with observations.
The spin rate properties of Galactic massive O-type stars
Authors: Holgado G. , Simón-Díaz S. , Herrero A. , Barbá R. H. 
Published: August 2024

AbstractWe present results from a recent study of the spin rate properties of a sample of more than 400 Galactic O-type stars surveyed by the IACOB and OWN projects. We combine vsini, Teff, and logg estimates with information about the spectroscopic binarity status for 285 of the stars in the sample, and provide a renewed overview about how the empirical distribution of projected rotational velocities in the O-star domain depends on mass, evolutionary and binary status. The obtained distributions are then compared with predictions of state-of-the-art population synthesis simulations including binary interaction, and used to provide hints about the initial velocity distribution of stars with masses in the range 15-80 M⊙.