bluuebunny/crossref_metadata_2025_split huggingface dataset:
Propagation of Alfvén waves in the charge starvation regime
Authors: Kumar Pawan , Gill Ramandeep , Lu Wenbin 
Published: September 2022

ABSTRACTWe present numerical simulation results for the propagation of Alfvén waves in the charge starvation regime. This is the regime where the plasma density is below the critical value required to supply the current for the wave. We analyse a conservative scenario where Alfvén waves pick up charges from the region where the charge density exceeds the critical value and advect them along at a high Lorentz factor. The system consisting of the Alfvén wave and charges being carried with it, which we call charge-carrying Alfvén wave (CC-AW), moves through a medium with small, but non-zero, plasma density. We find that the interaction between CC-AW and the stationary medium has a two-stream like instability which leads to the emergence of a strong electric field along the direction of the unperturbed magnetic field. The growth rate of this instability is of the order of the plasma frequency of the medium encountered by the CC-AW. Our numerical code follows the system for hundreds of wave periods. The numerical calculations suggest that the final strength of the electric field is of the order of a few per cent of the AW amplitude. Little radiation is produced by the sinusoidally oscillating currents associated with the instability during the linear growth phase. However, in the non-linear phase, the fluctuating current density produces strong EM radiation near the plasma frequency and limits the growth of the instability.
Period–colour and amplitude–colour relations for OGLE-δ Scuti stars in the Galactic bulge and LMC
Authors: Deka Mami , Kanbur Shashi M , Deb Sukanta , Das Susmita , Kurbah Kerdaris , Bellinger Earl P , Bhardwaj Anupam 
Published: September 2022

ABSTRACT
We present an analysis on the behaviour of the Galactic bulge and the Large Magellanic Cloud (LMC) δ Scuti stars in terms of period–colour and amplitude–colour (PCAC) relations at maximum, mean, and minimum light. The publicly available Optical Gravitational Lensing Experiment-IV (OGLE-IV) light curves for Galactic bulge and OGLE-III light curves for LMC δ Scuti stars are exploited for the analysis. It has been found that the Galactic bulge δ Scuti stars obey flat PC relations at maximum/mean/minimum light, while the LMC δ Scutis have sloped, sloped, and flat PC relations at maximum, mean, and minimum light, respectively. Both the Galactic bulge and the LMC δ Scutis have sloped, flat, and sloped AC relations at maximum, mean, and minimum light, respectively. These relations also show that Galactic δ Scutis are hotter as compared to their LMC counterparts. The period–amplitude (PA) relations for δ Scutis exhibit different behaviour in the Galactic bulge and the LMC. The LMC variables are found to have higher amplitudes at a given period. The amplitude of the Galactic bulge δ Scuti shows a bimodal distribution which can be modelled using a two-component Gaussian Mixture Model: one component with a lower amplitude and another with a higher amplitude. The observed behaviour of the δ Scuti PCAC relations can be explained using the theory of the interaction of hydrogen ionization front (HIF) and stellar photosphere as well as the PA diagram. We use mesa-rsp to calculate theoretical non-linear hydrodynamical pulsation models for δ Scuti stars with input metallicities of Z = 0.02 and Z = 0.008 appropriate for the Galactic bulge and LMC, respectively. The observed PCAC relations and theoretical calculations support the HIF–photosphere interaction theory.
TheXMMCluster Survey: an independent demonstration of the fidelity of the eFEDS galaxy cluster data products and implications for future studies
Authors: Turner D J , Giles P A , Romer A K , Wilkinson R , Upsdell E W , Klein M , Viana P T P , Hilton M , Bhargava S , Collins C A , Mann R G , Sahlén M , Stott J P 
Published: September 2022

ABSTRACTWe present the first comparison between properties of clusters of galaxies detected by the eROSITA Final Equatorial-Depth Survey (eFEDS) and the XMM Cluster Survey (XCS). We have compared, in an ensemble fashion, properties from the eFEDS X-ray cluster catalogue with those from the Ultimate XMM eXtragaLactic (XXL) survey project (XXL-100-GC). We find the redshift and temperature (TX) distributions to be similar, with a larger proportion of clusters above 4 keV in the XXL-100-GC sample; fractional temperature uncertainties are significantly larger in eFEDS compared to XXL. We find 62 eFEDS cluster candidates with XMM data (eFEDS-XMM sample); 10 do not have good enough XMM data to confirm or deny, 11 are classed as sample contaminants, and 4 have their X-ray flux contaminated by another source. The majority of eFEDS-XMM sources have longer XMM exposures than eFEDS, and most eFEDS positions are within 100 kpc of XCS positions. Our eFEDS-XCS sample of 37 clusters is used to calculate minimum sample contamination fractions of ∼18 and ∼9 per cent in the eFEDS X-ray and optically confirmed samples, respectively, in general agreement with eFEDS findings. We directly compare 29 X-ray luminosities (LX) measured by eFEDS and XCS, finding excellent agreement. Eight clusters have a TX measured by XCS and eFEDS, and we find that XMM temperatures are 25 ± 9 per cent larger than their eROSITA counterparts. Finally, we construct LX–TX scaling relations based on eFEDS and XCS measurements, which are in tension; the tension is decreased when we measure a third scaling relation with calibrated XCS temperatures.
Extending the energy range of AstroSat-CZTI up to 380 keV with compton spectroscopy
Authors: Kumar Abhay , Chattopadhyay Tanmoy , Vadawale Santosh V , Rao A R , Mithun N P S , Bhalerao Varun , Bhattacharya Dipankar 
Published: September 2022

ABSTRACT
The CZTI (Cadmium Zinc Telluride Imager) onboard AstroSat is a high energy coded mask imager and spectrometer in the energy range of 20–100 keV. Above 100 keV, the dominance of Compton scattering cross-section in CZTI results in a significant number of 2-pixel Compton events and these have been successfully utilized for polarization analysis of Crab pulsar and nebula (and transients like Gamma-ray bursts) in 100–380 keV. These 2-pixel Compton events can also be used to extend the spectroscopic energy range of CZTI up to 380 keV for bright sources. However, unlike the spectroscopy in primary energy range, where simultaneous background measurement is available from masked pixels, Compton spectroscopy requires blank sky observation for background measurement. Background subtraction, in this case, is non-trivial because of the presence of both short-term and long-term temporal variations in the data, which depend on multiple factors like earth rotation and the effect of South Atlantic Anomaly (SAA) regions etc. We have developed a methodology of background selection and subtraction that takes into account for these effects. Here, we describe these background selection and subtraction techniques and validate them using spectroscopy of Crab in the extended energy range of 30–380 keV region, and compare the obtained spectral parameters with the INTEGRAL results. This new capability allows for the extension of the energy range of AstroSat spectroscopy and will also enable the simultaneous spectropolarimetric study of other bright sources like Cygnus X-1.
Towards a multitracer timeline of star formation in the LMC – II. The formation and destruction of molecular clouds
Authors: Ward Jacob L , Kruijssen J M Diederik , Chevance Mélanie , Kim Jaeyeon , Longmore Steven N 
Published: September 2022

ABSTRACT
The time-scales associated with various stages of the star formation process represent major unknowns in our understanding of galactic evolution, as well as of star and planet formation. This is the second paper in a series aiming to establish a multitracer timeline of star formation in the Large Magellanic Cloud (LMC), focusing on the life cycle of molecular clouds. We use a statistical method to determine a molecular cloud lifetime in the LMC of $t_{\text{CO}}=11.8^{+2.7}_{-2.2}$ Myr. This short time-scale is similar to the cloud dynamical time, and suggests that molecular clouds in the LMC are largely decoupled from the effects of galactic dynamics and have lifetimes set by internal processes. This provides a clear contrast to atomic clouds in the LMC, of which the lifetimes are correlated with galactic dynamical time-scales. We additionally derive the time-scale for which molecular clouds and H ii regions co-exist as $t_{\text{fb}}=1.2^{+0.3}_{-0.2}$ Myr, implying an average feedback front expansion velocity of 12 km s−1, consistent with expansion velocities of H ii regions in the LMC observed directly using optical spectroscopy. Taken together, these results imply that the molecular cloud life cycle in the LMC proceeds rapidly and is regulated by internal dynamics and stellar feedback. We conclude by discussing our measurements in the context of previous work in the literature, which reported considerably longer lifetimes for molecular clouds in the LMC, and find that these previous findings resulted from a subjective choice in timeline calibration that is avoided by our statistical methodology.
Chemical properties of the central part of the Galactic nuclear stellar disc. Abundances in four classical Cepheids revisited
Authors: Kovtyukh V V , Korotin S A , Andrievsky S M , Matsunaga N , Fukue K 
Published: September 2022

ABSTRACT
This paper is a revised abundance analysis of four yellow supergiant stars Cepheids which are located in the Galactic nucleus. The results are based on the spectra secured with the help of Subaru telescope, which are of the better quality comparing to previously analysed spectra taken with the Infrared Telescope Facility. A significantly improved method of the effective temperature determination of program stars, which is based on the calibrating relations between the temperature and line depth ratios, was applied. The present results confirmed our previous finding about the solar metallicity level at the Galaxy centre. It is very likely that the four stars of our program were born from an interstellar medium having homogeneous chemical properties, since all the stars are located close to each other, have close pulsation periods, and hence the age. However, one of the stars has a somewhat increased abundance of all studied elements compared to the abundance in the other three stars. A possible reason of this fact is discussed.
Statistical investigation of the kinematic and thermal properties of supra-arcade downflows observed during a solar flare
Authors: Tan Guangyu , Hou Yijun , Tian Hui 
Published: September 2022

ABSTRACT
Supra-arcade downflows (SADs) are dark structures descending towards post-reconnection flare loops observed in extreme ultraviolet or X-ray observations and are closely related to magnetic reconnection during solar flares. Due to the lack of statistical study on SADs in a single flare, evolutions of kinematic and thermal properties of SADs during the flare process still remain obscure. In this work, we identified 81 SADs in a flare that occurred on 2013 May 22 using observations of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO). The kinematic properties of each SAD, including the appearance time, height, projective velocity, and acceleration were recorded. We found that the appearance heights of SADs become larger during the flare, which is likely due to the lift of the bottom of the plasma sheet. In the flare decay phase, the region where SADs mainly appear moves from the north part to the south side possibly related to a secondary eruption in the south side. The trajectories of most SADs can be fitted by one or two deceleration processes, while some special ones have positive accelerations during the descent. For the thermal properties, we selected 54 SADs, whose front and body could be clearly distinguished from the surrounding during the entire descent, to perform Differential Emission Measure analysis. It is revealed that the temperatures of the SAD front and body tend to increase during their downward courses, and the relationship between the density and temperature indicates that the heating is mainly caused by adiabatic compression.
Cluster environment quenches the star formation of low-mass satellite galaxies from the inside-out
Authors: Wang Bitao 
Published: September 2022

ABSTRACTEnvironment plays a critical role in the star formation history of galaxies. Tidal and hydrodynamical stripping, prominent in cluster environment, can remove the peripheral gas of galaxies and star formation may thus be environmentally suppressed from the outside-in. We revisit the environmental dependence of the radial gradient of specific star formation rate (sSFR) profile. We probe the radial gradient by using the archival spectral indices D4000n and HδA measured from SDSS fibre spectra, to indicate central sSFR and the total sSFR from fitting the spectral energy distribution. Despite the low spatial resolution, the wealth of SDSS data allows to disentangle the dependences on stellar mass, sSFR, and environment. We find that low-mass satellite galaxies in the mass range $9\lt \mathrm{log}\, \mathcal {M}_{\star }/\mathcal {M}_{\odot }\lt 9.8$ on average quench in more inside-out pattern compared to isolated galaxies matched in mass, sSFR, and fibre coverage. This environmental effect is particularly strong for galaxies below the star formation main sequence, and peaks for those in the core of massive clusters where the phase-space diagram reveals clear links between the inside-out quenching and orbital properties. Our results suggest that both tidal and hydrodynamical interactions in cluster environment suppress the star formation of satellites mainly from the inside-out. As accreted gas of low angular momentum from hot gas haloes is an important source for replenishing central gas reservoir, we discuss how gas stripping in clusters may lead to starvation and cause inside-out quenching when the outer star-forming discs are not significantly affected.
Searching for outliers in the Chandra Source Catalog
Authors: Swarm Dustin K , DeRoo C T , Liu Y , Watkins S 
Published: September 2022

ABSTRACT
Astronomers are increasingly faced with a deluge of information, and finding worthwhile targets of study in the sea of data can be difficult. Outlier identification studies are a method that can be used to focus investigations by presenting a smaller set of sources that could prove interesting because they do not follow the trends of the underlying population. We apply a principal component analysis (PCA) and an unsupervised random forest algorithm (uRF) to sources from the Chandra Source Catalog v.2 (CSC2). We present 119 high-significance sources that appear in all repeated applications of our outlier identification algorithm (OIA). We analyse the characteristics of our outlier sources and cross-match them with the SIMBAD data base. Our outliers contain several sources that were previously identified as having unusual or interesting features by studies. This OIA leads to the identification of interesting targets that could motivate more detailed study.
H i 21-cm absorption in radio-loud AGN with double-peaked [O iii] emission
Authors: Dutta Rajeshwari , Srianand Raghunathan 
Published: September 2022

ABSTRACT
Different physical processes in galaxy evolution, such as galaxy mergers that lead to coalescence of dual Active Galactic Nuclei (AGN) and outflows emanating from the narrow line region, can leave their imprint on the optical spectra of AGN in the form of double-peaked narrow emission lines. To investigate the neutral gas in the centres of such AGN, we have conducted a pilot survey of H i 21-cm absorption, using the upgraded Giant Metrewave Radio Telescope (uGMRT), in radio-loud AGN whose optical spectra show double-peaked [O iii] emission lines at z ≤ 0.4 (median z ≈ 0.14). Among the eight sources for which we could obtain clean spectra, we detect H i 21-cm absorption in three sources (detection rate of $38^{+36}_{-20}$ per cent) and find tentative indication of absorption in two other sources. The detection rate of H i 21-cm absorption is tentatively higher for the systems that show signatures of interaction or tidal disturbance (≳ 50 per cent) in the ground-based optical images than that for the systems that appear single and undisturbed (≈25 per cent). This is consistent with the high incidence of H i 21-cm absorption observed in z ≤ 0.2 galaxy mergers. Higher spatial resolution spectroscopy is required to confirm the origin of the H i absorbing gas, i.e. either gas infalling on to the radio-loud AGN, outflowing gas ejected by the AGN, or gas in rotation on the galactic-scale or circumnuclear discs.
Hepatotoxicity and the role of the gut–liver axis in dogs after oral administration of zinc oxide nanoparticles
Authors: Yi Jiangnan , Li Yuanliang , Mai Qianying , Li Yaxuan , Lin Yingying , Weng Xiaoshan , Ai Zhu , Li Mingze , Shang Peng , Iqbal Mujahid , Mehmood Khalid , Chang Yung-Fu , Tang Zhaoxin , Zhang Hui , Li Ying 
Published: September 2022

Abstract
Zinc oxide nanoparticles (ZnO NPs) have been used in many fields, and people are concerned about its effects on health. The present study reported the changes in liver metabolites and intestinal microbiota induced by overused ZnO NPs in dogs and explored the related mechanisms of liver injury induced by ZnO NPs. The results showed that overused ZnO NPs promote zinc accumulation in the liver and increase liver coefficient and serum liver-related indexes. In addition, the overuse of ZnO NPs increase the reactive oxygen species levels, affecting the hepatocyte antioxidant capacity and mitochondrial function. Results showed that ZnO NPs significantly inhibited the hepatocyte apoptosis via the Cytc pathway and promoted the autophagy via activating the mTOR/ATG5 pathway. Metabolic analysis of liver tissue showed that 81 metabolites changed overall and mainly affected the glycerophospholipid metabolism. ZnO NPs can significantly change the richness and diversity of the intestinal bacteria in dogs, increasing the abundance of Firmicutes and Actinobacteria while reducing the bacterial abundance of Proteobacteria. In conclusion, the results suggest that overexposure to ZnO NPs can lead to the disruption of intestinal microbiome and liver metabolites in dogs, which ultimately leads to liver damage.
Seasonal variation of vegetative stages and cysts of planktonic ciliates in a temperate coastal bay
Authors: Yu Ying , Zhang Wuchang , Feng Meiping , Xu Xiaofu 
Published: September 2022

Abstract
Marine planktonic ciliates serve as a key component of the plankton food web. Their vegetative stages have frequently been studied, whereas their cyst stages have largely been ignored. Seasonal encystment and excystment of ciliates has great implications for population persistence, maintenance of biodiversity and stability of ecosystem processes. Here, we investigated seasonal variation of planktonic ciliate cysts in surface sediments of Bohai Bay, and explore the relationships between cysts and environmental factors. Eight types of aloricate ciliate cysts were identified and only two species of tintinnid cysts were recognized, namely, Favella sp. and Helicostomella longa. Abundance of ciliate cysts was lowest in winter, and highest in summer. There was a significant positive correlation between abundance of ciliate cysts and vegetative cells, which supported the viewpoint that encystment could be induced by high population density. The species composition of ciliate cysts exhibited obvious seasonal variation, and water temperature was the key driving factor. The natural encystment event of ciliates may be triggered, enhanced and terminated by a rapid variation of temperature. Our study exhibited that ciliate cysts—served as a “seed bank” for vegetative populations—were common in temperate coastal waters, and seasonal changes of ciliate cysts are crucial to vegetative population dynamics.
Return to performance following severe ankle, knee, and hip injuries in National Basketball Association players
Authors: Bullock Garrett S , Ferguson Tyler , Arundale Amelia H , Martin Chelsea Leonard , Collins Gary S , Kluzek Stefan 
Published: September 2022

Abstract
The purpose of this study was to compare basketball performance markers 1 y prior to initial severe lower extremity injury, including ankle, knee, and hip injuries, to 1 and 2 y following injury during the regular National Basketball Association (NBA) season. Publicly available data were extracted through a reproducible extraction computed programmed process. Eligible participants were NBA players with at least three seasons played between 2008 and 2019, with a time-loss injury reported during the study period. Basketball performance was evaluated for season minutes, points, and rebounds. Prevalence of return to performance and linear regressions were calculated. A total of 285 athletes sustained a severe lower extremity injury. A total of 196 (69%) played for 1 y and 130 (45%) played for 2 y following the injury. A total of 58 (30%) players participated in a similar number of games and 57 (29%) scored similar points 1 y following injury. A total of 48 (37%) participated in a similar number of games and 55 (42%) scored a similar number of points 2 y following injury. Fewer than half of basketball players who suffered a severe lower extremity injury were participating at the NBA level 2 y following injury, with similar findings for groin/hip/thigh, knee, and ankle injuries. Fewer than half of players were performing at previous preinjury levels 2 y following injury. Suffering a severe lower extremity injury may be a prognostic factor that can assist sports medicine professionals to educate and set performance expectations for NBA players.
Structural basis for p53 binding to its nucleosomal target DNA sequence
Authors: Nishimura Masahiro , Takizawa Yoshimasa , Nozawa Kayo , Kurumizaka Hitoshi 
Published: September 2022

Abstract
The tumor suppressor p53 functions as a pioneer transcription factor that binds a nucleosomal target DNA sequence. However, the mechanism by which p53 binds to its target DNA in the nucleosome remains elusive. Here we report the cryo-electron microscopy structures of the p53 DNA-binding domain and the full-length p53 protein complexed with a nucleosome containing the 20 base-pair target DNA sequence of p53 (p53BS). In the p53-nucleosome structures, the p53 DNA-binding domain forms a tetramer and specifically binds to the p53BS DNA, located near the entry/exit region of the nucleosome. The nucleosomal position of the p53BS DNA is within the genomic p21 promoter region. The p53 binding peels the DNA from the histone surface, and drastically changes the DNA path around the p53BS on the nucleosome. The C-terminal domain of p53 also binds to the DNA around the center and linker DNA regions of the nucleosome, as revealed by hydroxyl radical footprinting. These results provide important structural information for understanding the mechanism by which p53 binds the nucleosome and changes the chromatin structure for gene activation.