bluuebunny/crossref_metadata_2025_split huggingface dataset:
A multiphase study of theoretical and observed light curves of classical Cepheids in the Magellanic Clouds
Authors: Kurbah Kerdaris , Deb Sukanta , Kanbur Shashi M , Das Susmita , Deka Mami , Bhardwaj Anupam , Randall Hugh Riley , Kalici Selim 
Published: March 2023

ABSTRACTWe present an analysis of the theoretical and observed light-curve parameters of the fundamental mode (FU) classical Cepheids in the Magellanic Clouds in V- and I- photometric bands. The state-of-the-art 1D non-linear radial stellar pulsation (RSP) code in mesa (mesa-rsp) has been utilized to generate the theoretical light curves using four sets of convection parameters. Theoretical light curves with two chemical compositions: Z = 0.008 and Z = 0.004 appropriate for the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), respectively, covered a wide range of periods ($3\lt P (\rm {d})\lt 32$). The observed light curves are taken from the OGLE-IV data base. We compare theoretical and observed Fourier parameters (FPs), and investigate the period–luminosity (PL), period–colour (PC), and amplitude–colour (AC) relations as a function of pulsation phase for short (log P &lt; 1), long (log P &gt; 1), and all periods. The multiphase relations obtained from theoretical and observed light curves in the PL/PC/AC plane are found to be dynamic in nature, with the effect more pronounced at Φ ∼ 0.75–0.85. Furthermore, a contrasting behaviour of the theoretical/observed multiphase PL and PC relations between the short and long periods has been found for both LMC and SMC. The analysis shows that multiphase PL relations are more stringent to test the models with observations over the FPs. Distances to the LMC/SMC determined using long period Cepheids are found to be in good agreement with the literature values when the term R21 is added to the PL relation.
GPU-based framework for detecting small Solar system bodies in targeted exoplanet surveys
Authors: Burdanov A Y , Hasler S N , de Wit J 
Published: March 2023

ABSTRACTSmall Solar system bodies are pristine remnants of Solar system formation, which provide valuable insights for planetary science and astronomy. Their discovery and cataloguing also have strong practical implications to life on Earth as the nearest asteroids could pose a serious impact threat. Concurrently with dedicated observational projects, searches for small bodies have been performed on numerous archival data sets from different facilities. Here, we present a framework to increase the scientific return of an exoplanet transit-search survey by recovering serendipitous detections of small bodies in its daily and archival data using a GPU-based synthetic tracking algorithm. As a proof of concept, we analysed $12\, \times 12\, \mathrm{arcmin^2}$ sky fields observed by the 1-m telescopes of the SPECULOOS survey. We analysed 90 sky fields distributed uniformly across the sky as part of the daily search for small bodies and 21 archival fields located within 5 deg from the ecliptic plane as part of the archival search (4.4 deg2 in total). Overall, we identified 400 known objects of different dynamical classes from Inner Main-belt Asteroids to Jupiter Trojans and 43 potentially new small bodies with no priors on their motion. We were able to reach limiting magnitude for unknown objects of V = 23.8 mag, and a retrieval rate of ∼80 per cent for objects with V &lt; 22 mag and V &lt; 23.5 mag for the daily and archival searches, respectively. SPECULOOS and similar exoplanet surveys can thus serve as pencil-beam surveys for small bodies and probe parameter space beyond V = 22 mag.
Age-divided mean stellar populations from full spectrum fitting as the simplified star formation and chemical evolution history of a galaxy: methodology and reliability
Authors: Lee Joon Hyeop , Pak Mina , Jeong Hyunjin , Oh Sree 
Published: March 2023

ABSTRACT
We introduce a practical methodology for investigating the star formation and chemical evolution history of a galaxy: age-divided mean stellar populations (ADPs) from full spectrum fitting. In this method, the mass-weighted mean stellar populations and mass fractions (fmass) of young and old stellar components in a galaxy are separately estimated, which are divided with an age cut (selected to be 109.5 yr ≈3.2 Gyr in this paper). To examine the statistical reliability of ADPs, we generate 10 000 artificial galaxy spectra, each of which consists of five random simple stellar population components. Using the Penalized PiXel-Fitting (ppxf) package, we conduct full spectrum fitting to the artificial spectra with noise as a function of wavelength, imitating the real noise of Sydney-Australian Astronomical Observatory Multi-object Integral field spectrograph (SAMI) galaxies. As a result, the Δ (= output − input) of age and metallicity appears to significantly depend on not only signal-to-noise ratio (S/N), but also luminosity fractions (flum) of young and old components. At given S/N and flum, Δ of young components tends to be larger than Δ of old components; e.g. σ(Δ[M/H]) ∼ 0.40 versus 0.23 at S/N = 30 and flum = 50 per cent. The age-metallicity degeneracy appears to be insignificant, but Δlog(age/yr) shows an obvious correlation with Δfmass for young stellar components ($\mathcal {R}\sim 0.6$). The impact of dust attenuation and emission lines appears to be mostly insignificant. We discuss how this methodology can be applied to spectroscopic studies of the formation histories of galaxies, with a few examples of SAMI galaxies.
Data science methodology for time-delay estimation and data preprocessing of the time-delay challenge
Authors: Leon-Anaya Luis , Cuevas-Tello Juan C , Valenzuela Octavio , Puente César A , Soubervielle-Montalvo Carlos 
Published: March 2023

ABSTRACT
The vast amount of astronomical information that has become available over this decade has far exceeded that of the last century. The heterogeneity of the data and its overwhelming magnitude have made it impossible to perform manual analysis. As a consequence, new techniques have been developed and different strategies have been amalgamated, such as data science and data mining, in order to carry out more in-depth and exhaustive analyses in search of the extraction of the knowledge contained in data. This paper introduces a data science methodology that consists of successive stages, with the core of this proposal being the step of data preprocessing, with the aim of reducing the complexity of the analysis and enabling hidden knowledge in the data to be uncovered. The proposed methodology was tested on a set of data consisting of artificial light curves that try to mimic the behaviour of the strong gravitational lens phenomenon, as supplied by the Time Delay Challenge 1 (TDC1). Under the data science methodology, diverse statistical methods were implemented for data analysis, and cross-correlation and dispersion methods were applied for the time-delay estimation of strong lensing systems. With this methodology, we obtained time-delay estimations from the TDC1 data set and compared them with earlier results reported by the COSmological MOnitoring of GRAvItational Lenses project (COSMOGRAIL). The empirical evidence leads us to conclude that, with the proposed methodology, we achieve a greater accuracy in estimating time delays compared with estimations made with raw data.
SRG/eROSITA discovery of a radio-faint X-ray candidate supernova remnant SRGe J003602.3+605421 = G121.1−1.9
Authors: Khabibullin I I , Churazov E M , Bykov A M , Chugai N N , Sunyaev R A 
Published: March 2023

ABSTRACT
We report the discovery of a candidate X-ray supernova remnant SRGe J003602.3+605421 = G121.1−1.9 in the course of the SRG/eROSITA all-sky survey. The object is located at (l, b) = (121.1°, −1.9°), is ≈36 arcmin in angular size, and has a nearly circular shape. Clear variations in the spectral shape of the X-ray emission across the object are detected, with the emission from the inner (within 9 arcmin) and outer (9–18 arcmin) parts dominated by iron and oxygen/neon lines, respectively. The non-equilibrium plasma emission model is capable of describing the spectrum of the outer part with an initial gas temperature 0.1 keV, final temperature 0.5 keV, and ionization age ∼2 × 1010 cm−3 s. The observed spectrum of the inner region is more complicated (plausibly due to the contribution of the outer shell) and requires a substantial overabundance of iron for all models that we have tried. The derived X-ray absorption is equal to (4–6) × 1021 cm−2, locating the object at a distance beyond 1.5 kpc, and implying its age ∼(5–30) × 1000 yr. No bright radio, infrared, H α, or gamma-ray counterpart of this object has been found in the publicly available archival data. A model invoking a canonical 1051 erg explosion (either SN Ia or core collapse) in the hot and tenuous medium in the outer region of the Galaxy ∼9 kpc away might explain the bulk of the observed features. This scenario can be tested with future deep X-ray and radio observations.
Properties and evolution of dual and offset AGN in the ASTRID simulation at z ∼ 2
Authors: Chen Nianyi , Di Matteo Tiziana , Ni Yueying , Tremmel Michael , DeGraf Colin , Shen Yue , Holgado A Miguel , Bird Simeon , Croft Rupert , Feng Yu 
Published: March 2023

ABSTRACT
We examine the dual [both black hole (BH) active] and offset (one BH active and in distinct galaxies) active galactic nucleus (AGN) population (comprising ∼ 2000 pairs at $0.5\, \text{kpc}\lesssim \Delta r\lt 30\, \text{kpc}$) at z = 2 ∼ 3 in the ASTRID simulation covering (360 cMpc)3. The dual (offset) AGN make up 3.0(0.5) per cent of all AGN at z = 2. The dual fraction is roughly constant while the offset fraction increases by a factor of 10 from z = 4 ∼ 2. Compared with the full AGN population, duals are characterized by low MBH/M* ratios, high specific star formation rates (sSFR) of $\sim 1\, \text{Gyr}^{-1}$, and high Eddington ratios (∼0.05, double that of single AGN). Dual AGNs are formed in major galaxy mergers (typically involving $M_\text{halo}\lt 10^{13}\, M_\odot$), with simular-mass BHs. At small separations (when host galaxies are in the late phase of the merger), duals become 2 ∼ 8 times brighter (albeit more obscured) than at larger separations. 80 per cent of the bright, close duals would merge within $\sim 500\, \text{Myr}$. Notably, the initially less-massive BHs in duals frequently become the brighter AGN during galaxy mergers. In offset AGN, the active BH is typically ≳ 10 times more massive than its non-active counterpart and than most BHs in duals. Offsets are predominantly formed in minor galaxy mergers with the active BH residing in the centre of massive haloes ($M_\text{ halo}\sim 10^{13-14}\, \mathrm{M}_\odot$). In these deep potentials, gas stripping is common and the secondary quickly deactivates. The stripping also leads to inefficient orbital decay amongst offsets, which stall at $\Delta r\sim 5\, \text{kpc}$ for a few hundred Myrs.
Effects of folate on telomere length and chromosome stability of human fibroblasts and melanoma cells in vitro: a comparison of folic acid and 5-methyltetrahydrofolate
Authors: Wang Han , Ni Juan , Guo Xihan , Xue Jinglun , Wang Xu 
Published: March 2023

Abstract
Telomere length (TL), which is maintained by human telomerase reverse transcriptase (hTERT; component of telomerase) and/or TRF1/TRF2 (core components of shelterin) via different mechanisms, is essential for chromosomal stability and cell survival. Folates comprise a group of essential B9 vitamin that involve in DNA synthesis and methylation. This study aimed to evaluate the effects of folic acid (FA) and 5-methyltetrahydrofolate (5-MeTHF) on TL, chromosome stability, and cell survival of telomerase-negative BJ and telomerase-positive A375 cells in vitro. BJ and A375 cells were cultured in modified medium with FA or 5-MeTHF (22.6 or 2260 nM) for 28 days. TL and mRNA expression were determined by RT-qPCR. Chromosome instability (CIN) and cell death were measured by CBMN-Cyt assay. Results showed that abnormal TL elongation was observed in FA- and 5-MeTHF-deficient BJ cells. The TL of A375 cells showed no obvious alterations under the FA-deficient condition but was significantly elongated under the 5-MeTHF-deficient condition. In both BJ and A375 cells, FA and 5-MeTHF deficiency caused decreased TRF1, TRF2, and hTERT expression, increased CIN and cell death; while a high concentration of 5-MeTHF induced elongated TL, elevated CIN, increased TRF1 and TRF2 expression, and decreased hTERT expression, when compared with the FA counterpart. These findings concluded that folate deficiency induced TL instability in both telomerase-negative and -positive cells, and FA was more efficient in maintaining TL and chromosome stability compared with 5-MeTHF.
Single-molecule visualization of stalled replication-fork rescue by the Escherichia coli Rep helicase
Authors: Whinn Kelsey S , Xu Zhi-Qiang , Jergic Slobodan , Sharma Nischal , Spenkelink Lisanne M , Dixon Nicholas E , van Oijen Antoine M , Ghodke Harshad 
Published: March 2023

Abstract
Genome duplication occurs while the template DNA is bound by numerous DNA-binding proteins. Each of these proteins act as potential roadblocks to the replication fork and can have deleterious effects on cells. In Escherichia coli, these roadblocks are displaced by the accessory helicase Rep, a DNA translocase and helicase that interacts with the replisome. The mechanistic details underlying the coordination with replication and roadblock removal by Rep remain poorly understood. Through real-time fluorescence imaging of the DNA produced by individual E. coli replisomes and the simultaneous visualization of fluorescently-labeled Rep, we show that Rep continually surveils elongating replisomes. We found that this association of Rep with the replisome is stochastic and occurs independently of whether the fork is stalled or not. Further, we visualize the efficient rescue of stalled replication forks by directly imaging individual Rep molecules as they remove a model protein roadblock, dCas9, from the template DNA. Using roadblocks of varying DNA-binding stabilities, we conclude that continuation of synthesis is the rate-limiting step of stalled replication rescue.
Scale effect of circularly polarized luminescent signal of matter
Authors: Sun Siyu , Li Xiaolin , Xu Chen , Li Yan , Wu YongZhen , Feringa Ben L , Tian He , Ma Xiang 
Published: March 2023

ABSTRACT
Circularly polarized luminescence (CPL) is an important part in the research of modern luminescent materials and photoelectric devices. Usually, chiral molecules or chiral structures are the key factors to induce CPL spontaneous emission. In this study, a scale-effect model based on scalar theory was proposed to better understand the CPL signal of luminescent materials. Besides chiral structures being able to induce CPL, achiral ordered structures can also have a significant influence on CPL signals. These achiral structures are mainly reflected in the particle scale in micro-order or macro-order, i.e. the CPL signal measured under most conditions depends on the scale of the ordered medium, and does not reflect the inherent chirality of the excited state of the luminescent molecule. This kind of influence is difficult to be eliminated by simple and universal strategies in macro-measurement. At the same time, it is found that the measurement entropy of CPL detection may be the key factor to determine the isotropy and anisotropy of the CPL signal. This discovery would bring new opportunities to the research of chiral luminescent materials. This strategy can also greatly reduce the development difficulty of CPL materials and show high application potential in biomedical, photoelectric information and other fields.
Dynamics of synthetic yeast chromosome evolution shaped by hierarchical chromatin organization
Authors: Zhou Sijie , Wu Yi , Zhao Yu , Zhang Zhen , Jiang Limin , Liu Lin , Zhang Yan , Tang Jijun , Yuan Ying-Jin 
Published: March 2023

ABSTRACT
Synthetic genome evolution provides a dynamic approach for systematically and straightforwardly exploring evolutionary processes. Synthetic Chromosome Rearrangement and Modification by LoxP-mediated Evolution (SCRaMbLE) is an evolutionary system intrinsic to the synthetic yeast genome that can rapidly drive structural variations. Here, we detect over 260 000 rearrangement events after the SCRaMbLEing of a yeast strain harboring 5.5 synthetic yeast chromosomes (synII, synIII, synV, circular synVI, synIXR and synX). Remarkably, we find that the rearrangement events exhibit a specific landscape of frequency. We further reveal that the landscape is shaped by the combined effects of chromatin accessibility and spatial contact probability. The rearrangements tend to occur in 3D spatially proximal and chromatin-accessible regions. The enormous numbers of rearrangements mediated by SCRaMbLE provide a driving force to potentiate directed genome evolution, and the investigation of the rearrangement landscape offers mechanistic insights into the dynamics of genome evolution.
Strongyloides stercoralisin the US Military Health System
Authors: Taheri Branson , Kuo Huai-Ching , Hockenbury Nicole , Lu Dan , Mitre Edward , Hickey Patrick W 
Published: March 2023

AbstractBackgroundStrongyloides stercoralis is an intestinal nematode most commonly found in subtropical and tropical locations. Military service members are believed to be at increased risk of exposure due to their unique occupational exposures in endemic regions.MethodsBurden, clinical course, and risk factors associated with all Strongyloides infections within the US Military Health System from fiscal years 2012 to 2019 were assessed by manual chart review of records with International Classification of Diseases, Ninth Revision/Tenth Revision codes for Strongyloides infection. Infection risk in demographic subgroups based on region of birth, military occupation, and age was quantified with univariate analysis and multivariate logistic regression.ResultsWe reviewed 243 charts based on diagnosis coding, yielding 210 confirmed diagnoses (86.4%). Immigrant patients born in Latin America/Caribbean, sub-Saharan Africa, and East Asia/Pacific regions had statistically significant increased risk ratios of infection at 34.4, 32.0, and 22.4, respectively, when compared to patients born in Europe and North America. In univariate analysis, active duty members in the healthcare occupational category had a statistically significant increased risk ratio of infection at 2.31 compared to those outside this occupation. Multivariate logistic regression analysis demonstrated that occupational categories of healthcare, admininstrative/support, warfighter/combat specialist, and engineering/repair/maintenance occupations, being an immigrant patient, and age ≥65 were all associated with statistically significant increased odds ratios for infection.ConclusionsIn the Military Health System, occupational exposures, region of birth, and age serve as risk factors for Strongyloides infection. Because infections may be chronic, the impact of targeted screening programs to complement routine medical care should be considered.
Analyzing an Emerging Pandemic on Twitter: Monkeypox
Authors: Cooper Lauren N , Radunsky Alexander P , Hanna John J , Most Zachary M , Perl Trish M , Lehmann Christoph U , Medford Richard J 
Published: March 2023

AbstractBackgroundSocial media platforms like Twitter provide important insights into the public's perceptions of global outbreaks like monkeypox. By analyzing tweets, we aimed to identify public knowledge and opinions on the monkeypox virus and related public health issues.MethodsWe analyzed English-language tweets using the keyword “monkeypox” from 1 May to 23 July 2022. We reported gender, ethnicity, and race of Twitter users and analyzed tweets to identify predominant sentiment and emotions. We performed topic modeling and compared cohorts of users who self-identify as LGBTQ+ (an abreviation for lesbian, gay, bisexual, transgender, queer, and/or questioning) allies versus users who do not, and cohorts identified as “bots” versus humans.ResultsA total of 48 330 tweets were written by LGBTQ+ self-identified advocates or allies. The mean sentiment score for all tweets was −0.413 on a −4 to +4 scale. Negative tweets comprised 39% of tweets. The most common emotions expressed were fear and sadness. Topic modeling identified unique topics among the 4 cohorts analyzed.ConclusionsThe spread of mis- and disinformation about monkeypox was common in our tweet library. Various conspiracy theories about the origins of monkeypox, its relationship to global economic concerns, and homophobic and racial comments were common. Conversely, many other tweets helped to provide information about monkeypox vaccines, disease symptoms, and prevention methods. Discussion of rising monkeypox case numbers globally was also a large aspect of the conversation.ConclusionsWe demonstrated that Twitter is an effective means of tracking sentiment about public healthcare issues. We gained insight into a subset of people, self-identified LGBTQ+ allies, who were more affected by monkeypox.
Surveillance of Severe Acute Respiratory Syndrome Coronavirus 2 and Variants Using Digital Droplet Polymerase Chain Reaction at a Large University and Healthcare System in California
Authors: Stafylis Chrysovalantis , Pernet Olivier , Hernandez-Tamayo Cassidy , Kovacs Andrea , Emerson Jane , Ward Pamela M , Van Orman Sarah , Gilliland Frank , Conti David , Weisenhaus Maia , Ghanem-Uzqueda Angie , Yepez Daniel , Stellar Sofia , Tadanki Aditya P , Max Jillian , Fottrell Honour , Ong Ethan , Navarro Sabrina , Moses Kaelyn , Akaolisa Michael , Hosseini Bijan , Sunesara Shaleen , Wang Yuzhu , Strum Earl , Casagrande Yolee , Arenas Nathalie , Williams Christopher , Thomas Paul , Chu Tara , Hu Howard , Klausner Jeffrey D 
Published: March 2023

Abstract

Background
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with different infectivity, transmission potential, and morbidity change the characteristics of local epidemics and affect vaccine effectiveness. As part of the University of Southern California COVID-19 Pandemic Research Center's efforts to understand, control, and inform local community on coronavirus disease 2019 (COVID-19), we implemented a SARS-CoV-2 surveillance program among students, employees, and USC Keck Medical Center patients. We present the epidemiology and distribution of SARS-CoV-2 and its variants among the population.

Methods
We used digital droplet reverse-transcriptase polymerase chain reaction (PCR) to analyze in real-time remnant SARS-CoV-2 PCR-positive saliva specimens stored at the USC Keck Medicine laboratory between September 2020 and April 2022. Samples were tested for the original strain (A20) and 9 SARS-CoV-2 variants: α(B.1.1.7, Q.1–Q.8), β(B.1.351, B.1.351.2, B.1.351.3), γ(P.1, P.1.1, P.1.2), δ(B.1.617.2), δ+(or δ417N), ε(B.1.427 and B.1.429), η(B.1.525), λ(C.37) and ο(B.1.1.529, ΒΑ.1, BA.2). We reviewed deidentified health information from positive cases including demographics, history of COVID-19 (eg, symptoms, hospitalizations, and repeat infections), and COVID-19 vaccination status.

Results
We reviewed 1169 cases and determined the variant type of 482 specimens: 77 specimens were original strain, 119 “Delta”, 165 “Omicron”. The original strain was detected during the third and fourth quarters of 2020. The Delta variant appeared during the second quarter of 2021, whereas Omicron appeared in the fourth quarter of 2021.

Conclusions
Prospectively tracking SARS-CoV-2 variants in a university population and a hospital system, utilizing a low-cost, high-throughput PCR assay, was feasible. Local variant monitoring remains important to inform prevention and control efforts among university and clinical settings.