bluuebunny/crossref_metadata_2025_split huggingface dataset:
Behavioral flexibility in Wasmannia auropunctata (Hymenoptera: Formicidae)
Authors: Ortiz-Alvarado Yarira , Fernández-Casas Rafael , Ortiz-Alvarado Carlos A , Diaz-Iglesias Emily , Rivera-Marchand Bert 
Published: July 2021

Abstract
Worker division of labor is a defining trait in social insects. Many species are characterized by having behavioral flexibility where workers perform non-typical tasks for their age depending on the colony’s needs. Worker division of labor and behavioral flexibility were examined in the little fire ant Wasmannia auropunctata (Roger, 1863), for which age-related division of labor has been found. Young workers perform nursing duties which include tending of brood and queens, and colony defense, while older workers forage. When nurses were experimentally removed from the colony, foragers were observed carrying out nursing and colony defense duties, yet when foragers were removed nurses did not forage precociously. We also administered juvenile hormone analog, methoprene, to workers. When methoprene was applied, foragers increased their nursing and defense activities while nurses became mainly idle. The behavioral flexibility of foragers of the little fire ant may be evidence of an expansion of worker’s repertoires as they age; older workers can perform tasks they have already done in their life while young individuals are not capable of performing tasks ahead of time. This may be an important adaptation associated with the success of this ant as an invasive species.
Nonmedical Cannabis Use: Patterns and Correlates of Use, Exposure, and Harm, and Cancer Risk
Authors: Cohn Amy M , Blount Benjamin C , Hashibe Mia 
Published: July 2021

AbstractCannabis has certain health benefits, but some people may experience harms from use. Co-use of tobacco and cannabis is common. Smoke from cannabis contains many of the same carcinogens and toxicants as the smoke from tobacco, raising concerns that cannabis smoking may be a risk factor for cancer. With growing access to and acceptance of medical and nonmedical cannabis, there is an urgent need to understand the risks and benefits of the current modes of cannabis use and how cannabis may be associated with cancer risk. This monograph summarizes a session from a National Cancer Institute Symposium on nonmedical cannabis use and cancer risk. We had 3 objectives: describe the relation between nonmedical cannabis use and cancer risk, delineate patterns and correlates of cannabis co-use with tobacco, and document potentially harmful inhalational exposure resulting from smoked and vaped cannabis. Methodological limitations in the literature and future research recommendations are provided.
SARS-CoV-2 Incidence and Transmission in 48 K-12 Virginia Public Schools During Community Surge
Authors: Rowland Leah C , Hahn Jennifer B , Jelderks Trudy L , Welch Nancy M , Ramirez Dana W E 
Published: July 2021

Abstract
Among 20 681 students and 4282 staff, the in-school transmission of SARS-CoV-2 appeared low during highest community spread and at 3- to 6-foot distancing. Nine of 820 school cases (1.1%) resulted in spread, with only one student-to-staff transmission. A school epidemiologist and mitigation audit teams were useful.
Safeguarding genome integrity under heat stress in plants
Authors: Han Shin-Hee , Kim Jae Young , Lee June-Hee , Park Chung-Mo 
Published: July 2021

Abstract
Heat stress adversely affects an array of molecular and cellular events in plant cells, such as denaturation of protein and lipid molecules and malformation of cellular membranes and cytoskeleton networks. Genome organization and DNA integrity are also disturbed under heat stress and, accordingly, plants have evolved sophisticated adaptive mechanisms that either protect their genomes from deleterious heat-induced damage or stimulate genome restoration responses. In particular, it is emerging that DNA damage responses are a critical defense process that underlies the acquisition of thermotolerance in plants, during which molecular players constituting the DNA repair machinery are rapidly activated. In recent years, thermotolerance genes that mediate the maintenance of genome integrity or trigger DNA repair responses have been functionally characterized in various plant species. Furthermore, accumulating evidence supports that genome integrity is safeguarded through multiple layers of thermoinduced protection routes in plant cells, including transcriptome adjustment, orchestration of RNA metabolism, protein homeostasis, and chromatin reorganization. In this review, we summarize topical progress and research trends in understanding how plants cope with heat stress to secure genome intactness. We focus on molecular regulatory mechanisms by which plant genomes are secured against the DNA-damaging effects of heat stress and DNA damage is effectively repaired. We also explore the practical interface between heat stress response and securing genome integrity in view of developing biotechnological ways of improving thermotolerance in crop species under global climate change, a worldwide ecological concern in agriculture.
Spectral distortion constraints on photon injection from low-mass decaying particles
Authors: Bolliet Boris , Chluba Jens , Battye Richard 
Published: July 2021

ABSTRACT
Spectral distortions (SDs) of the cosmic microwave background (CMB) provide a powerful tool for studying particle physics. Here we compute the distortion signals from decaying particles that convert directly into photons at different epochs during cosmic history, focusing on injection energies $E_\mathrm{inj}\lesssim 20\, \mathrm{keV}$. We deliver a comprehensive library of SD solutions, using CosmoTherm to compute the SD signals, including effects on the ionization history and opacities of the Universe, and blackbody-induced stimulated decay. Then, we use data from COBE/FIRAS and EDGES to constrain the properties of the decaying particles. We explore scenarios where these provide a dark matter (DM) candidate or constitute only a small fraction of DM. We complement the SD constraints with CMB anisotropy constraints, highlighting new effects from injections at very-low photon energies ($h\nu \lesssim 10^{-4}\, {\rm eV}$). Our model-independent constraints exhibit rich structures in the lifetime-energy domain, covering injection energies Einj ≃ 10−10 eV − 10 keV and lifetimes $\tau _X\simeq 10^5-10^{33}\, \mathrm{s}$. We discuss the constraints on axions and axion-like particles, revising existing SD constraints in the literature. Our limits are competitive with other constraints for axion masses $m_a c^2\gtrsim 27\, {\rm eV}$ and we find that simple estimates based on the overall energetics are generally inaccurate. Future CMB spectrometers could significantly improve the obtained constraints, thus providing an important complementary probe of early-universe particle physics.
Predicting the self-lensing population in optical surveys
Authors: Wiktorowicz Grzegorz , Middleton Matthew , Khan Norman , Ingram Adam , Gandhi Poshak , Dickinson Hugh 
Published: July 2021

ABSTRACT
The vast majority of binaries containing a compact object and a regular star spend most of their time in a quiescent state where no strong interactions occur between components. Detection of these binaries is extremely challenging and only few candidates have been detected through optical spectroscopy. Self-lensing represents a new means of detecting compact objects in binaries, where gravitational lensing of the light from the visible component by the compact object produces periodic optical flares. Here we show that current and planned large-area optical surveys can detect a significant number (∼100–10 000s) of these self-lensing binaries and provide insights into the properties of the compact lenses. We show that many of the predicted population of observable self-lensing binaries will be observed with multiple self-lensing flares; this both improves the chances of detection and also immediately distinguishes them from chance-alignment micro-lensing events. Through self-lensing we can investigate long – but previously hidden – stages of binary evolution and consequently provide new constraints on evolutionary models that impact the number and nature of double compact object mergers.
The reflectance spectra of CV–CK carbonaceous chondrites from the near-infrared to the visible
Authors: Tanbakouei S , Trigo-Rodríguez Josep M , Llorca J , Moyano-Cambero C E , Williams I P , Rivkin Andrew S 
Published: July 2021

ABSTRACT
Carbonaceous chondrite meteorites are so far the only available samples representing carbon-rich asteroids and in order to allow future comparison with samples returned by missions such as Hayabusa 2 and OSIRIS-Rex, it is important to understand their physical properties. Future characterization of asteroid primitive classes, some of them targeted by sample-return missions, requires a better understanding of their mineralogy, the consequences of the exposure to space weathering, and how both affect the reflectance behaviour of these objects. In this paper, the reflectance spectra of two chemically related carbonaceous chondrites groups, precisely the Vigrano (CVs) and Karoonda (CKs), are measured and compared. The available sample suite includes polished sections exhibiting different petrologic types: from 3 (very low degree of thermal metamorphism) to 5 (high degree of thermal metamorphism). We found that the reflective properties and the comparison with the Cg asteroid reflectance class point towards a common chondritic reservoir from which the CV–CK asteroids collisionally evolved. In that scenario, the CV and CK chondrites could be originated from 221 Eos asteroid family, but because of its collisional disruption, both chondrite groups evolved separately, experiencing different stages of thermal metamorphism, annealing, and space weathering.
On the importance of Ca ii photoionization by the hydrogen lyman transitions in solar flare models
Authors: Osborne C M J , Heinzel P , Kašparová J , Fletcher L 
Published: July 2021

ABSTRACT
The forward fitting of solar flare observations with radiation–hydrodynamic simulations is a common technique for learning about energy deposition and atmospheric evolution during these explosive events. A frequent spectral line choice for this process is Ca ii 854.2 nm due to its formation in the chromosphere and substantial variability. It is important to ensure that this line is accurately modelled to obtain the correct interpretation of observations. Here, we investigate the importance of photoionization of Ca ii to Ca iii by the hydrogen Lyman transitions, whilst the Lyman continuum is typically considered in this context in simulations, the associated bound–bound transitions are not. This investigation uses two RADYN flare simulations and reprocesses the radiative transfer using the Lightweaver framework which accounts for the overlapping of all active transitions. The Ca ii 854.2 nm line profiles are found to vary significantly due to photoionization by the Lyman lines, showing notably different shapes and even reversed asymmetries. Finally, we investigate to what extent these effects modify the energy balance of the simulation and the implications on future radiation–hydrodynamic simulations. There is found to be a 10–15 per cent change in detailed optically thick radiative losses from considering these photoionization effects on the calcium lines in the two simulations presented, demonstrating the importance of considering these effects in a self-consistent way.
Damped Lyman-α absorbers from Sloan digital sky survey DR16Q with Gaussian processes
Authors: Ho Ming-Feng , Bird Simeon , Garnett Roman 
Published: July 2021

ABSTRACT
We present a new catalogue of Damped Lyman-α absorbers from SDSS DR16Q, as well as new estimates of their statistical properties. Our estimates are computed with the Gaussian process models presented in Garnett et al., Ho, Bird & Garnett with an improved model for marginalizing uncertainty in the mean optical depth of each quasar. We compute the column density distribution function (CDDF) at 2 &lt; z &lt; 5, the line density (dN/dX), and the neutral hydrogen density (ΩDLA). Our Gaussian process model provides a posterior probability distribution of the number of DLAs per spectrum, thus allowing unbiased probabilistic predictions of the statistics of DLA populations even with the noisiest data. We measure a non-zero column density distribution function for $N_{\rm {HI}}\lt 3 \times 10^{22} \, \rm {cm}^{-2}$ with $95{{\ \rm per\ cent}}$ confidence limits, and $N_{\rm {HI}}\lesssim 10^{22} \, \rm {cm}^{-2}$ for spectra with signal-to-noise ratios &gt;4. Our results for DLA line density and total hydrogen density are consistent with previous measurements. Despite a small bias due to the poorly measured blue edges of the spectra, we demonstrate that our new model can measure the DLA population statistics when the DLA is in the Lyman-β forest region. We verify our results are not sensitive to the signal-to-noise ratios and redshifts of the background quasars although a residual correlation remains for detections from zQSO &lt; 2.5, indicating some residual systematics when applying our models on very short spectra, where the SDSS spectral observing window only covers part of the Lyman-α forest.
Novae heat their food: mass transfer by irradiation
Authors: Ginzburg Sivan , Quataert Eliot 
Published: July 2021

ABSTRACT
A nova eruption irradiates and heats the donor star in a cataclysmic variable to high temperatures Tirr, causing its outer layers to expand and overflow the Roche lobe. We calculate the donor’s heating and expansion both analytically and numerically, under the assumption of spherical symmetry, and find that irradiation drives enhanced mass transfer from the donor at a rate $\dot{m}\propto T_{\rm irr}^{5/3}$, which reaches $\dot{m}\sim 10^{-6}\textrm {~M}_\odot \textrm {~yr}^{-1}$ at the peak of the eruption – about a thousand times faster than during quiescence. As the nova subsides and the white dwarf cools down, $\dot{m}$ drops to lower values. We find that under certain circumstances, the decline halts and the mass transfer persists at a self-sustaining rate of $\dot{m}\sim 10^{-7}\textrm {~M}_\odot \textrm {~yr}^{-1}$ for up to ∼103 yr after the eruption. At this rate, irradiation by the white dwarf’s accretion luminosity is sufficient to drive the mass transfer on its own. The self-sustaining rate is close to the white dwarf’s stable burning limit, such that this bootstrapping mechanism can simultaneously explain two classes of puzzling binary systems: recurrent novae with orbital periods ≈2 h (T Pyxidis and IM Normae) and long-lived supersoft X-ray sources with periods ≈4 h (RX J0537.7–7034 and 1E 0035.4–7230). Whether or not a system reaches the self-sustaining state is sensitive to the donor’s chromosphere structure, as well as to the orbital period change during nova eruptions.
The spatially offset quasar E1821+643: new evidence for gravitational recoil
Authors: Jadhav Yashashree , Robinson Andrew , Almeyda Triana , Curran Rachel , Marconi Alessandro 
Published: July 2021

ABSTRACT
A galaxy merger is expected to cause the formation of a supermassive black hole (SMBH) binary, which itself eventually coalesces through the anisotropic emission of gravitational waves. This may result in the merged SMBH receiving a recoil kick velocity ∼100–1000 kms−1, causing it to oscillate in the gravitational potential of the host galaxy. The luminous quasar E1821+643, identified as an SMBH recoil candidate via spectropolarimetry observations, shows Doppler shifting of the broad emission lines in direct and scattered light, consistent with a relative velocity of 2100 km s−1 between the quasar nucleus and host galaxy. In this paper, we attempt to detect the expected spatial displacement using a combination of optical spectroastrometry and Hubble Space Telescope (HST) narrow-band images. The spectroastrometry reveals a relative spatial displacement between the quasar nucleus and the gas emitting the [O iii] λλ4959, 5007 lines of ∼130 mas (∼580 pc) to the north-west. Our HST images resolve the [O iii] emission on sub-arcsecond scales, showing that it is asymmetrically distributed, extending to radial distances ∼0.5−0.6 arcsec from the nucleus in a wide arc running from the north-east around to the west. A simulated spectroastrometry observation based on the HST [O iii] image indicates that only a small fraction of the measured displacement can be attributed to the asymmetric [O iii] emission. This displacement therefore appears to be a real spatial offset of the quasar nucleus with respect to the narrow-line region, presumed to be located at the host galaxy centre, further supporting the interpretation that a post-merger gravitational recoil of the SMBH has occurred in E1821+643.
The cold circumgalactic medium in emission: Mg ii haloes in TNG50
Authors: Nelson Dylan , Byrohl Chris , Peroux Celine , Rubin Kate H R , Burchett Joseph N 
Published: July 2021

ABSTRACT
We outline theoretical predictions for extended emission from Mg ii, tracing cool ∼104 K gas in the circumgalactic medium (CGM) of star-forming galaxies in the high-resolution TNG50 cosmological magnetohydrodynamical simulation. We synthesize surface brightness maps of this strong rest-frame ultraviolet metal emission doublet (λλ2796, 2803), adopting the assumption that the resonant scattering of Mg ii can be neglected and connecting to recent and upcoming observations with the Keck/KCWI, VLT/MUSE, and BlueMUSE optical integral field unit spectrographs. Studying galaxies with stellar masses 7.5 &lt; log (M⋆/M⊙) &lt; 11 at redshifts z = 0.3, 0.7, 1, and 2 we find that extended Mg ii haloes in emission, similar to their Ly α counterparts, are ubiquitous across the galaxy population. Median surface brightness profiles exceed 10−19 erg s−1 cm−2 arcsec−2 in the central $\sim \,$10 s of kpc, and total halo Mg ii luminosity increases with mass for star-forming galaxies, reaching 1040 erg s−1 for M⋆ ∼ 109.5 M⊙. Mg ii halo sizes increase from a few kpc to ≳ 20 kpc at the highest masses, and sizes are larger for haloes in denser environments. Mg ii haloes are highly structured, clumpy, and asymmetric, with isophotal axial ratio increasing with galaxy mass. Similarly, the amount and distribution of Mg ii emission depends on the star formation activity of the central galaxy. Kinematically, inflowing versus outflowing gas dominates the Mg ii luminosity at high and low galaxy masses, respectively, although the majority of Mg ii halo emission at z ∼ 0.7 traces near-equilibrium fountain flows and gas with non-negligible rotational support, rather than rapidly outflowing galactic winds.
Two Reference-Quality Sea Snake Genomes Reveal Their Divergent Evolution of Adaptive Traits and Venom Systems
Authors: Li An , Wang Junjie , Sun Kuo , Wang Shuocun , Zhao Xin , Wang Tingfang , Xiong Liyan , Xu Weiheng , Qiu Lei , Shang Yan , Liu Runhui , Wang Sheng , Lu Yiming 
Published: July 2021

Abstract
True sea snakes (Hydrophiini) are among the last and most successful clades of vertebrates that show secondary marine adaptation, exhibiting diverse phenotypic traits and lethal venom systems. To better understand their evolution, we generated the first chromosome-level genomes of two representative Hydrophiini snakes, Hydrophis cyanocinctus and H. curtus. Through comparative genomics we identified a great expansion of the underwater olfaction-related V2R gene family, consisting of more than 1,000 copies in both snakes. A series of chromosome rearrangements and genomic structural variations were recognized, including large inversions longer than 30 megabase (Mb) on sex chromosomes which potentially affect key functional genes associated with differentiated phenotypes between the two species. By integrating multiomics we found a significant loss of the major weapon for elapid predation, three-finger toxin genes, which displayed a dosage effect in H. curtus. These genetic changes may imply mechanisms that drove the divergent evolution of adaptive traits including prey preferences between the two closely related snakes. Our reference-quality sea snake genomes also enrich the repositories for addressing important issues on the evolution of marine tetrapods, and provide a resource for discovering marine-derived biological products.
Genome-Wide SNPs Clarify a Complex Radiation and Support Recognition of an Additional Cat Species
Authors: Trindade Fernanda J , Rodrigues Maíra R , Figueiró Henrique V , Li Gang , Murphy William J , Eizirik Eduardo 
Published: July 2021

AbstractPhylogenetic reconstruction and species delimitation are often challenging in the case of recent evolutionary radiations, especially when postspeciation gene flow is present. Leopardus is a Neotropical cat genus that has a long history of recalcitrant taxonomic problems, along with both ancient and current episodes of interspecies admixture. Here, we employ genome-wide SNP data from all presently recognized Leopardus species, including several individuals from the tigrina complex (representing Leopardus guttulus and two distinct populations of Leopardus tigrinus), to investigate the evolutionary history of this genus. Our results reveal that the tigrina complex is paraphyletic, containing at least three distinct species. While one can be assigned to L. guttulus, the other two remain uncertain regarding their taxonomic assignment. Our findings indicate that the “tigrina” morphology may be plesiomorphic within this group, which has led to a longstanding taxonomic trend of lumping these poorly known felids into a single species.
Endogenous Retroviruses Drive Lineage-Specific Regulatory Evolution across Primate and Rodent Placentae
Authors: Sun Ming-an , Wolf Gernot , Wang Yejun , Senft Anna D , Ralls Sherry , Jin Jinpu , Dunn-Fletcher Caitlin E , Muglia Louis J , Macfarlan Todd S 
Published: July 2021

Abstract
In mammals, the placenta mediates maternal–fetal nutrient and waste exchange and acts in an immunomodulatory way to facilitate maternal–fetal tolerance. The placenta is highly diverse across mammalian species, yet the molecular mechanisms that distinguish the placenta of human from other mammals are not fully understood. Using an interspecies transcriptomic comparison of human, macaque, and mouse late-gestation placentae, we identified hundreds of genes with lineage-specific expression—including dozens that are placentally enriched and potentially related to pregnancy. We further annotated the enhancers for different human tissues using epigenomic data and demonstrate that the placenta and chorion are unique in that their enhancers display the least conservation. We identified numerous lineage-specific human placental enhancers and found they highly overlap with specific families of endogenous retroviruses (ERVs), including MER21A, MER41A/B, and MER39B that were previously linked to immune response and placental function. Among these ERV families, we further demonstrate that MER41A/B insertions create dozens of lineage-specific serum response factor-binding loci in human, including one adjacent to FBN2, a placenta-specific gene with increased expression in humans that produces the peptide hormone placensin to stimulate glucose secretion and trophoblast invasion. Overall, our results demonstrate the prevalence of lineage-specific placental enhancers which are frequently associated with ERV insertions and likely facilitate the lineage-specific evolution of the mammalian placenta.