bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of Ca II emission around polluted white dwarfs
Authors: Fröhlich V. , Regály Zs. 
Published: October 2024

Context. Dozens of white dwarfs with anomalous metal polluted atmospheres are currently known to host dust and gas discs. The line profiles of the Ca II triplet emitted by the gas discs show a significant asymmetry. In recent decades, researchers have also discovered several minor planets orbiting such white dwarf stars.
Aims. The most challenging burden of modelling gas discs around metal polluted white dwarfs is to simultaneously explain the asymmetry and metal pollution of the star’s atmosphere over a certain period of time. Furthermore, models should also be consistent with other aspects of the observations, such as the morphology of the emission lines. This paper aims to construct a self-consistent model to explain the simultaneous white dwarf pollution and Ca II line asymmetry over at least three years.
Methods. In our model, an asteroid disintegrates in an eccentric orbit, periodically entering below the star’s Roche limit. The debris resulting from the disintegration sublimates at a temperature of 1500 K, producing gas that viscously spreads to form a disc. The evolution of the disc is studied over a period of 1.2 years (over 21 000 orbits) using two-dimensional hydrodynamic simulations. Synthetic Ca II line profiles are calculated using the surface mass density and velocity distributions provided by the simulations, taking into account for the first time the asymmetric velocity distribution in the disc.
Results. An asteroid disintegrating on an eccentric orbit gives rise to the formation of an asymmetric disc and asymmetric Ca II triplet emission. Our model can explain the periodic reversal of the redshifted and blueshifted peak of the Ca II lines caused by the precession of the disc on timescales of 10.6–177.4 days.
Conclusions. Our work suggests that the persistence of Ca II asymmetry over decades and its periodic change in the peaks can be explained by asteroids on eccentric orbits in two scenarios. In the first case, the asteroid disrupts on a short timescale (a couple of orbits), and the gas has a low viscosity range (0.001 < α < 0.05) to maintain the Ca II signal for decades. In the other scenario, the asteroid disrupts on a timescale of a year, and the viscosity of the gas is required to be high, α = 0.1.
Chaotic magnetic disconnections trigger flux eruptions in accretion flows channeled onto magnetically saturated Kerr black holes
Authors: Nalewajko Krzysztof , Kapusta Mateusz , Janiuk Agnieszka 
Published: October 2024

Context. Magnetized accretion flow onto a black hole (BH) may lead to the accumulation of poloidal magnetic flux across its horizon, which for high BH spin can power far-reaching relativistic jets. The BH magnetic flux is subject to a saturation mechanism by means of magnetic flux eruptions involving relativistic magnetic reconnection. Such accretion flows have been described as magnetically arrested disks (MAD) or magnetically choked accretion flows (MCAF).
Aims. The main goal of this work is to describe the onset of relativistic reconnection and initial development of magnetic flux eruption in accretion flow onto magnetically saturated BHs.
Methods. We analyzed the results of 3D general relativistic ideal magnetohydrodynamic (GRMHD) numerical simulations in the Kerr metric, starting from weakly magnetized geometrically thick tori rotating either prograde or retrograde. We integrated large samples of magnetic field lines in order to probe magnetic connectivity with the BH horizon.
Results. The boundary between magnetically connected and disconnected domains coincides roughly with enthalpy equipartition. The geometrically constricted innermost part of the disconnected domain develops a rigid structure of magnetic field lines – rotating slowly and insensitive to the BH spin orientation. The typical shape of innermost disconnected lines is a double spiral converging to a sharp inner tip anchored at the single equatorial current layer. The foot-points of magnetic flux eruptions are found to zip around the BH along with other azimuthal patterns.
Conclusions. Magnetic flux eruptions from magnetically saturated accreting BHs can be triggered by minor density gaps in the disconnected domain, resulting from the chaotic disconnection of plasma-depleted magnetospheric lines. Accretion flow is effectively channeled along the disconnected lines toward the current layer, and further toward the BH by turbulent cross-field diffusion. Rotation of flux eruption foot-points may contribute to the variability of BH crescent images.
PRODIGE – envelope to disk with NOEMA
Authors: Gieser C. , Pineda J. E. , Segura-Cox D. M. , Caselli P. , Valdivia-Mena M. T. , Maureira M. J. , Hsieh T. H. , Busch L. A. , Bouscasse L. , Lopez-Sepulcre A. , Neri R. , Kuffmeier M. , Henning Th. , Semenov D. , Cunningham N. , Jimenez-Serra I. 
Published: October 2024

Context. The formation of stars has been subject to extensive studies in the past decades on scales from molecular clouds to proto-planetary disks. It is still not fully understood how the surrounding material in a protostellar system, which often shows asymmetric structures with complex kinematic properties, feeds the central protostar(s) and their disk(s).
Aims. We study the spatial morphology and kinematic properties of the molecular gas surrounding the IRS3A and IRS3B protostellar systems in the L1448N region located in the Perseus molecular cloud.
Methods. We present 1 mm Northern Extended Millimeter Array (NOEMA) observations of the large program PROtostars & DIsks: Global Evolution (PRODIGE). We analyzed the kinematic properties of molecular lines. Because the spectral profiles are complex, the lines were fit with up to three Gaussian velocity components. The clustering algorithm called density-based spatial clustering of applications with noise (DBSCAN) was used to disentangle the velocity components in the underlying physical structure.
Results. We discover an extended gas bridge (≈3000 au) surrounding both the IRS3A and IRS3B systems in six molecular line tracers (C18O, SO, DCN, H2CO, HC3N, and CH3OH). This gas bridge is oriented in the northeast-southwest direction and shows clear velocity gradients on the order of 100 km s−1 pc−1 toward the IRS3A system. We find that the observed velocity profile is consistent with analytical streamline models of gravitational infall toward IRS3A. The high-velocity C18O (2-1) emission toward IRS3A indicates a protostellar mass of ≈1.2 M⊙.
Conclusions. While high angular resolution continuum data often show IRS3A and IRS3B in isolation, molecular gas observations reveal that these systems are still embedded within a large-scale mass reservoir, whose spatial morphology and velocity profiles are complex. The kinematic properties of the extended gas bridge are consistent with gravitational infall toward the protostar IRS3A.
When LAMOST meets Gaia DR3
Authors: Zhang Ruyuan , Wang Guo-Jian , Lu Yuxi(Lucy) , Guo Sufen , Lucatello Sara , Fu Xiaoting , Wang Haifeng , Wang Luqian , Schiappacasse-Ulloa José , Chen Jianxing , Han Zhanwen 
Published: October 2024

Context. Open clusters (OCs) are excellent probes as their age and abundance can be tightly constrained, allowing us to explore the distribution of metallicity and composition across the disk of the Milky Way. By conducting a comprehensive analysis of the metallicity of OCs, we can obtain valuable information about the history of their chemical enrichment. Moreover, by observing stars in different regions of the Milky Way, we can identify significant spatial structures in their chemical composition and abundance. This enables us to understand stellar birth radii through chemical tagging. Nevertheless, it remains challenging to infer the original positions of OCs using current data alone.
Aims. The aim of this study is to investigate the distribution of metallicity in the solar neighborhood using a large dataset from Gaia DR3 combined with LAMOST spectra. With accurate ages and metallicity measurements, we can determine birth radii for the stars and attempt to understand their migration pattern.
Methods. We chose a total of 1131 OCs within 3 kpc of the Sun from the Gaia DR3 and LAMOST DR8 low-resolution spectral database (R=1800). We used an artificial neural network to correct the LAMOST data by incorporating high-resolution spectral data from GALAH DR3 (R=28 000). The average metallicity of the OCs was determined based on the reliable [Fe/H] values for their members. We then examined the distribution of metallicity across different regions within the Galaxy and inferred birth radii of the OCs from their age and metallicity.
Results. The correction method presented here can partially eliminate the systematic offset for LAMOST data. We discuss the metal- licity trend as a function of Galactocentric distance and the guiding radii. We also compare these observational results with those from chemo-dynamic simulations. Values derived from observational metallicity data are slightly lower than predicted values when the uncertainties are not considered. However, the metallicity gradients are consistent with previous calculations. Finally, we investigated the birthplace of OCs and find hints that the majority of OCs near the Sun have migrated from the outer Galactic disk.
Detecting the near-infrared afterglows of high-redshift gamma-ray bursts using CAGIRE
Authors: Fortin F. , Atteia J. L. , Nouvel de la Flèche A. , Valentin H. , Boulade O. , Corre D. , Turpin D. , Secroun A. , Basa S. , Dolon F. , Floriot J. , Lombardo S. , Le Borgne J. F. , Watson A. M. , Lee W. H. 
Published: October 2024

Context. Transient sky astronomy is entering a new era with the advent of the Space Variable Objects Monitor mission (SVOM), successfully launched on 22 June 2024. The primary goal of SVOM is to monitor the hard X-ray sky searching for gamma-ray bursts (GRBs). On top of its on-board follow-up capabilities, SVOM will be backed by its ground segment composed of several facilities, including the near-infrared (NIR) imager CAGIRE. Mounted on the robotic telescope COLIBRI, it will be a unique instrument capable of performing fast follow-up of GRB afterglows in the J and H bands, ideal for capturing high-redshift (z>6) and/or obscured GRBs.
Aims. This paper is aimed at estimating the performances of CAGIRE for GRB NIR afterglow detection based on the characteristics of the detector and the specificities of the COLIBRI telescope. Quickly fading GRB afterglows pose challenges that should be addressed by adapting observing strategies to the capabilities of CAGIRE.
Methods. We used an end-to-end image simulator to produce realistic CAGIRE images, taking into account the results from the characterisation of the ALFA detector used by CAGIRE. We implemented a GRB afterglow generator that simulates infrared light curves and spectra based on published observation of distant GRBs (z>6).
Results. We retrieved the photometry of nine GRB afterglows in various scenarios covered by CAGIRE. Capturing afterglows as early as one minutes after the burst allows for the identification of a NIR counterpart in the brightest four events. When artificially redshifted even further away, these events remain detectable by CAGIRE up to z=9.6 in the J band and z=13.3 in H band, indicating the pioneering potential of CAGIRE in identifying the most distant GRBs to date.
Probing Na in giant exoplanets with ESPRESSO and 3D NLTE stellar spectra
Authors: Canocchi G. , Morello G. , Lind K. , Carleo I. , Stangret M. , Pallé E. 
Published: October 2024

Context. Neutral sodium was the first atom that was detected in an exoplanetary atmosphere using the transmission spectroscopy technique. To date, it remains the most successfully detected species due to its strong doublet in the optical at 5890 Å and 5896 Å. However, the center-to-limb variation (CLV) of these lines in the host star can bias the Na I detection. When combined with the Rossiter-McLaughlin (RM) effect, the CLV can mimic or obscure a planetary absorption feature if it is not properly accounted for.
Aims. This work aims to investigate the impact of three-dimensional (3D) radiation hydrodynamic stellar atmospheres and non-local thermodynamic equilibrium (NLTE) radiative transfer on the modeling of the CLV+RM effect in single-line transmission spectroscopy to improve the detection and characterization of exoplanet atmospheres.
Methods. We produced a grid of 3D NLTE synthetic spectra for Na I for FGK-type dwarfs within the following parameter space: Teff = 4500–6500 K, log g = 4.0–5.0, and [Fe/H] = [−0.5, 0, 0.5]. This grid was then interpolated to match the stellar parameters of four stars hosting well-known giant exoplanets, generating stellar spectra to correct for the CLV+RM effect in their transmission spectra. We used archival observations taken with the high-resolution ESPRESSO spectrograph.
Results. Our work confirms the Na I detections in three systems, namely WASP-52b, WASP-76b, and WASP-127b, also improving the accuracy of the measured absorption depth. Furthermore, we find that 3D NLTE stellar models can explain the spectral features in the transmission spectra of HD 209458b without the need for any planetary absorption. In the grid of stellar synthetic spectra, we observe that the CLV effect is stronger for stars with low Teff and high log g. However, the combined effect of CLV and RM is highly dependent on the orbital geometry of the planet-star system.
Conclusions. With the continuous improvement of instrumentation, it is crucial to use the most accurate stellar models available to correct for the CLV+RM effect in high-resolution transmission spectra to achieve the best possible characterization of exoplanet atmospheres. This will be fundamental in preparation for instruments such as ANDES at the Extremely Large Telescope to fully exploit its capabilities in the near future. We make our grid of 3D NLTE synthetic spectra for Na I publicly available.
Impfpflicht im Gesundheitswesen – „Der Drops ist gelutscht!“  Eine
qualitative Studie zu Wahrnehmungen und Dynamiken in Pflegeteams aus Sicht von
Pflegefachkräften
Authors: Stagge Maya , Rädel-Ablass Katharina , Roddewig Marion , Henne Melissa , Fehling Patrick , Polat Abdulillah , Schliz Klaus 
Published: October 2024

ZusammenfassungDie explorative Querschnittsstudie analysiert die Auswirkungen der
COVID-19-Impfpflicht auf Wahrnehmungen und die Dynamik in Pflegeteams. Die 27
leitfadengestützten Interviews mit Pflegefachkräften enthüllen, dass der Druck
zur Impfung und die Einführung der Impfpflicht im Gesundheitswesen zu Spaltungen
und konfliktgeladenen Interaktionen zwischen geimpften und ungeimpften
Teammitgliedern führten. Diese Konflikte haben die Arbeitsqualität und das
Teambewusstsein negativ beeinträchtigt, was in erhöhten Kündigungsraten und
einer anhaltenden Belastung der Pflegeteams resultierte.
Some Thiazolopyrimidine Derivatives: Synthesis, DFT, Cytotoxicity, and Pharmacokinetics Modeling Study
Authors: Ramadan Sayed K. , Alzahrani Abdullah Y. A. , El-Helw Eman A. E. 
Published: October 2024

AbstractA pyrimidinethione candidate carrying pyrazole and thiophene scaffolds was produced by a Biginelli cyclocondensation reaction of a pyrazolecarbaldehyde with pentan-2,4-dione and thiourea. To create some heteroannulated thiazolopyrimidines, the pyrimidinethione was subjected to cyclocondensation reactions with ethyl chloroacetate, 1,2-dibromoethane, chloroacetonitrile, and oxalyl chloride. A DFT simulation was performed for a frontier-orbital analysis to determine the molecular geometry. Among the products, 6-acetyl-7-methyl-5-[1-phen­yl-3-(2-thienyl)-1H-pyrazol-4-yl]-5H-[1,3]thiazolo[3,2-a]pyrimidine-2,3-dione displayed the highest softness and the lowest energy gap in the DFT calculations. Moreover, it had the highest electrophilicity index, suggesting possible biological impacts. The compounds obtained were evaluated against cell lines of breast adenocarcinoma (MCF7) and hepatocellular carcinoma (HepG2) as antiproliferative agents. A simulation of the molecular docking of our compounds with the epidermal growth factor receptor demonstrated the rationality of our design and identified the binding mode. A model pharmacokinetics analysis showed that the products have the expected and desirable drug-like and bioavailability properties.
Advances in the Light-Promoted Transformations of N-Heterocyclic Carbene Ligated Boryl Radicals
Authors: Xuan Jun , Xie Yang 
Published: October 2024

AbstractOrganoboron compounds are integral to modern life, with extensive applications in synthesis, materials science, medicine, and various other domains closely linked to human endeavors. NHC-BH3, noted for its stability, ease of synthesis, and high reactivity as a boryl radical precursor, has emerged as a key focus in boryl radical chemistry. Recently, the visible-light-induced single electron transfer (SET) and hydrogen atom transfer (HAT) processes have garnered considerable interest, presenting innovative strategies for generating boryl radicals from NHC-BH3. In the context of this review, our focus is on the synthesis of C–B and X–B bonds under visible light irradiation, facilitated by NHC-BH3. Furthermore, we explored the role of NHC-BH3 as a hydrogen donor or halogen atom transfer reagent in the construction of C–C bonds.1	Introduction2	Hydroboration3	Borylation4	Construction of X–B Bonds (X = N, O, S)5	Halogen Atom Transfer Reagent and Hydrogen Donor6	Conclusion
Frequency and Clinical Outcomes of Respiratory Infections in Children with Cancer Presenting with Febrile Illness
Authors: Srinivasan Arathi , Sekar Ramya Manur , Chandy Sara , Sundaram Balasubramanian 
Published: October 2024

Objectives Fever is a known complication in pediatric cancer patients when on chemotherapy for which prompt initiation of empiric antibiotics is the single most important life-saving intervention. Nearly two-thirds of all children are treated without identifying the source of fever. Molecular diagnostics can improve management of febrile episodes and reduce unnecessary antibiotic use. The purpose of our study was to evaluate the pathogenic etiology of febrile episodes and analyze their clinical characteristics.
Materials and Methods We conducted a prospective observational study at our tertiary care institution from January 2019 to March 2020, to identify the etiology of febrile episodes with or without neutropenia in pediatric cancer patients and to study their clinical outcomes.
Results Forty febrile episodes were observed among 27 patients over a period of 15 months. The mean age group was 5 years. In 28 febrile episodes without a focus (70%), a respiratory organism (virus, bacteria, or coinfection) was detected. Rhinovirus was the most common single respiratory isolate (47.36%), followed by Streptococcus pneumoniae (21.05%) and six episodes had multiple viral isolates (21.42%). There was no prolonged hospitalization, need for intensive care unit or oxygen requirement, or mortality. The most common antibiotic used in empiric management was piperacillin–tazobactam. Aminoglycosides were added when there was a clinical suspicion of resistant organism.
Conclusion Around 70% of febrile episodes without a focus or documented infection in cancer children had a respiratory pathogen identified in nasopharyngeal swab. Molecular diagnostics greatly enhances diagnostic sensitivity and thereby individualizes the management of febrile illness in these children.
Survey on the distribution of medical imaging frequencies and dose levels for CT examinations in a comprehensive hospital in Shanghai
Authors: Yang Fanqiaochu , Qu Liangyong , Yao Jie , Zhou Zhijun , Gao Linfeng 
Published: October 2024

Abstract
With the continuous advancement and clinical application of CT technology, the increasing collective dose burden from CT scans and associated potential health risks have become significant concerns in radiation protection. Current research increasingly focuses on the cumulative effective dose (CED) resulting from multiple CT scans, often revealing patients with high CEDs, even exceeding 100 mSv. However, reports on CEDs from multiple CT scans in China are scarce. Therefore, we investigated the distribution of CT scan frequencies and CEDs at a comprehensive hospital in Shanghai, examining data from 1 October 2022, to 30 April 2024, sourced from the hospital’s radiology information system. The effective dose (E) was estimated using conversion factors k and DLP values from Radiation Dose Structured Reports (RDSR). We assessed the number of CT examinations conducted per patient and evaluated the CED over 1.6 years. During this period, 112 339 CT examinations were performed. Significant differences in CT examination frequencies were observed across different age groups and examination regions (P < 0.01). A total of 78.43% of patients underwent only one CT examination in 1.6 years, while 0.03% had more than 10 examinations, with a maximum of 15. Of the patients, 67.78% (76,142 individuals) received a CED less than 10 mSv, 0.05% (53 patients) received a CED over 50 mSv, and one patient exceeded 100 mSv. In conclusion, this study underscored the necessity of monitoring patients with high CT examination frequencies and CEDs, highlighting the importance of justification and optimization in medical radiation protection.
STGRL: SNN based two-stage geomagnetic road localization method
Authors: Luo Qinghua , Yu Mutong , Yan Xiaozhen , Liu Boyuan , Su Yuhao , Yang Longxin , Wang Lan 
Published: October 2024

Abstract
Geomagnetic navigation is a widely used positioning method capable of correcting the cumulative errors of odometers and inertial navigation systems, thereby ensuring long-distance positioning for vehicles in GPS-denied environments. However, common geomagnetic road navigation algorithms are susceptible to measurement noise, which hinder improvements in positioning efficiency and accuracy. To address this issue, this paper proposes a Siamese Neural Network (SNN) based two-stage geomagnetic road localization method. First, attitude angle information is combined with geomagnetic scalar and vector value to establish geomagnetic reference database to increase the feature dimensions of geomagnetic matching. Then, we use the Random Forest algorithm to perform a coarse matching of the data sequence to determine the current road, balancing the increased computational load resulting from the addition of feature dimensions. Finally, to further reduce the impact of random noise, this paper employs the SNN algorithm based on Transformer Encoder for fine matching of the data sequence. Experiments show that compared to existing methods, the average absolute positioning error of our algorithm has been reduced from 32.36 m to 4.07 m, and the increase in computational load is kept within an acceptable range.
Differential evolution-based time domain decomposition method for multi-impact vibration signals of reciprocating machinery
Authors: Dou Quanli , Song Yedong , Zhang Zhenjing , Zhang Jinjie 
Published: October 2024

Abstract
To solve the problem of extracting the impact component from the complex time-domain vibration signal of reciprocating machinery vibration signals, a differential evolution (DE)-based time domain decomposition method is proposed to achieve adaptive extraction of impact components. The method establishes new decomposition window containing three adjustment parameters to adapt to multiple forms of impact components. Furthermore, with the optimization objectives of minimizing reconstruction loss, amplitude moment loss, and similarity loss, a decomposition parameter optimization algorithm based on DE is established to achieve the optimization process of decomposition parameters. The results of processing simulated and actual vibration signals of diesel engines show that the new method can adaptively and accurately identify the impact component and impact time center in the vibration component, with a signal reconstruction loss of less than 2.5% and a decomposition time of only 54.1 s.