• 12C/13C isotopic ratios in red-giant stars of the open cluster NGC 6791

      Szigeti, László; Mészáros, Szabolcs; Smith, Verne V; Cunha, Katia; Lagarde, Nadège; Charbonnel, Corinne; García-Hernández, D A; Shetrone, Matthew; Pinsonneault, Marc; Allende Prieto, Carlos; et al. (OXFORD UNIV PRESS, 2018-03)
      Carbon isotope ratios, along with carbon and nitrogen abundances, are derived in a sample of 11 red-giant members of one of the most metal-rich clusters in the Milky Way, NGC 6791. The selected red-giants have a mean metallicity and standard deviation of [Fe/H] = +0.39 +/- 0.06 (Cunha et al. 2015). We used high-resolution H-band spectra obtained by the SDSS-IV Apache Point Observatory Galactic Evolution Experiment. The advantage of using high-resolution spectra in the H band is that lines of CO are well represented and their line profiles are sensitive to the variation of C-12/C-13. Values of the C-12/C-13 ratio were obtained from a spectrum synthesis analysis. The derived C-12/C-13 ratios varied between 6.3 and 10.6 in NGC 6791, in agreement with the final isotopic ratios from thermohaline-induced mixing models. The ratios derived here are combined with those obtained for more metal poor red-giants from the literature to examine the correlation between C-12/C-13, mass, metallicity, and evolutionary status.
    • The 25 parsec local white dwarf population

      Holberg, J. B.; Oswalt, T. D.; Sion, E. M.; McCook, G. P.; Univ Arizona, Lunar & Planetary Lab (OXFORD UNIV PRESS, 2016-11-01)
      We have extended our detailed survey of the local white dwarf population from 20 to 25 pc, effectively doubling the sample volume, which now includes 232 stars. In the process, newstars within 20 pc have been added, a more uniform set of distance estimates as well as improved spectral and binary classifications are available. The present 25 pc sample is estimated to be about 68 per cent complete (the corresponding 20 pc sample is now 86 per cent complete). The space density of white dwarfs is unchanged at 4.8 +/- 0.5 x 10(-3) pc(-3). This new study includes a white dwarf mass distribution and luminosity function based on the 232 stars in the 25 pc sample. We find a significant excess of single stars over systems containing one or more companions (74 per cent versus 26 per cent). This suggests mechanisms that result in the loss of companions during binary system evolution. In addition, this updated sample exhibits a pronounced deficiency of nearby 'Sirius-like' systems. 11 such systems were found within the 20 pc volume versus only one additional system found in the volume between 20 and 25 pc. An estimate of white dwarf birth rates during the last similar to 8 Gyr is derived from individual remnant cooling ages. A discussion of likely ways new members of the local sample may be found is provided.
    • 2D-FFTLog: efficient computation of real-space covariance matrices for galaxy clustering and weak lensing

      Fang (方啸), Xiao; Eifler, Tim; Krause, Elisabeth; Univ Arizona, Dept Astron; Univ Arizona, Steward Observ; Univ Arizona, Dept Phys (OXFORD UNIV PRESS, 2020-06-17)
      Accurate covariance matrices for two-point functions are critical for inferring cosmological parameters in likelihood analyses of large-scale structure surveys. Among various approaches to obtaining the covariance, analytic computation is much faster and less noisy than estimation from data or simulations. However, the transform of covariances from Fourier space to real space involves integrals with two Bessel integrals, which are numerically slow and easily affected by numerical uncertainties. Inaccurate covariances may lead to significant errors in the inference of the cosmological parameters. In this paper, we introduce a 2D-FFTLog algorithm for efficient, accurate, and numerically stable computation of non-Gaussian real-space covariances for both 3D and projected statistics. The 2D-FFTLog algorithm is easily extended to perform real-space bin-averaging. We apply the algorithm to the covariances for galaxy clustering and weak lensing for a Dark Energy Survey Year 3-like and a Rubin Observatory's Legacy Survey of Space and Time Year 1-like survey, and demonstrate that for both surveys, our algorithm can produce numerically stable angular bin-averaged covariances with the flat sky approximation, which are sufficiently accurate for inferring cosmological parameters. The code COSMOCOV for computing the real-space covariances with or without the flat-sky approximation is released along with this paper.
    • 3D hydrodynamic simulations of carbon burning in massive stars

      Cristini, A.; Meakin, C.; Hirschi, R.; Arnett, D.; Georgy, C.; Viallet, M.; Walkington, I.; Univ Arizona, Dept Astron (OXFORD UNIV PRESS, 2017-10)
      We present the first detailed 3D hydrodynamic implicit large eddy simulations of turbulent convection of carbon burning in massive stars. Simulations begin with radial profiles mapped from a carbon-burning shell within a 15M circle dot 1D stellar evolution model. We consider models with 128(3), 256(3), 512(3), and 1024(3) zones. The turbulent flow properties of these carbon-burning simulations are very similar to the oxygen-burning case. We performed a mean field analysis of the kinetic energy budgets within the Reynolds-averaged Navier-Stokes framework. For the upper convective boundary region, we find that the numerical dissipation is insensitive to resolution for linear mesh resolutions above 512 grid points. For the stiffer, more stratified lower boundary, our highest resolution model still shows signs of decreasing sub-grid dissipation suggesting it is not yet numerically converged. We find that the widths of the upper and lower boundaries are roughly 30 per cent and 10 per cent of the local pressure scaleheights, respectively. The shape of the boundaries is significantly different from those used in stellar evolution models. As in past oxygen-shell-burning simulations, we observe entrainment at both boundaries in our carbon-shell-burning simulations. In the large Peclet number regime found in the advanced phases, the entrainment rate is roughly inversely proportional to the bulk Richardson number, Ri(B) (alpha Ri(B)(-alpha) a, 0.5 less than or similar to alpha less than or similar to 1.0). We thus suggest the use of Ri(B) as a means to take into account the results of 3D hydrodynamics simulations in new 1D prescriptions of convective boundary mixing.
    • The 4-Celled Tetrabaena socialis Nuclear Genome Reveals the Essential Components for Genetic Control of Cell Number at the Origin of Multicellularity in the Volvocine Lineage

      Featherston, Jonathan; Arakaki, Yoko; Hanschen, Erik R; Ferris, Patrick J; Michod, Richard E; Olson, Bradley J S C; Nozaki, Hisayoshi; Durand, Pierre M; Univ Arizona, Dept Ecol & Evolutionary Biol (OXFORD UNIV PRESS, 2018-04)
      Multicellularity is the premier example of a major evolutionary transition in individuality and was a foundational event in the evolution of macroscopic biodiversity. The volvocine chlorophyte lineage is well suited for studying this process. Extant members span unicellular, simple colonial, and obligate multicellular taxa with germ-soma differentiation. Here, we report the nuclear genome sequence of one of the most morphologically simple organisms in this lineage-the 4-celled colonial Tetrabaena socialis and compare this to the three other complete volvocine nuclear genomes. Using conservative estimates of gene family expansions a minimal set of expanded gene families was identified that associate with the origin of multicellularity. These families are rich in genes related to developmental processes. A subset of these families is lineage specific, which suggests that at a genomic level the evolution of multicellularity also includes lineagespecific molecular developments. Multiple points of evidence associate modifications to the ubiquitin proteasomal pathway (UPP) with the beginning of coloniality. Genes undergoing positive or accelerating selection in the multicellular volvocines were found to be enriched in components of the UPP and gene families gained at the origin of multicellularity include components of the UPP. A defining feature of colonial/multicellular life cycles is the genetic control of cell number. The genomic data presented here, which includes diversification of cell cycle genes and modifications to the UPP, align the genetic components with the evolution of this trait.
    • 6&6: A Transdisciplinary Approach to Art–Science Collaboration

      Clark, Sarah E; Magrane, Eric; Baumgartner, Thomas; Bennett, Scott E K; Bogan, Michael; Edwards, Taylor; Dimmitt, Mark A; Green, Heather; Hedgcock, Charles; Johnson, Benjamin M; et al. (OXFORD UNIV PRESS, 2020-07-29)
      Despite an historical connection between the arts and sciences, in the past century, the two disciplines have been greatly siloed. However, there is a renewed interest in collaboration across the arts and sciences to support conservation practice by understanding and communicating complex environmental, social, and cultural challenges in novel ways. 6&6 was created as a transdisciplinary art-science initiative to promote a deeper appreciation of the Sonoran Desert. Six artists and six scientists were paired to create work that explored conservation issues in the Sonoran Desert and the Gulf of California. In-depth interviews were conducted with the artists and scientists throughout the 4-year initiative to understand the impact of 6&6 on their personal and professional behaviors and outlook. The findings from this case study reveal the role that intensive, place-based, and transdisciplinary art-science programs can play in shaping narratives to better communicate the patterns and processes of nature and human-environment interactions.
    • A search for optical and near-infrared counterparts of the compact binary merger GW190814

      Thakur, A. L.; Dichiara, S.; Troja, E.; Chase, E. A.; Sanchez-Ramirez, R.; Piro, L.; Fryer, C. L.; Butler, N. R.; Watson, A. M.; Wollaeger, R. T.; et al. (OXFORD UNIV PRESS, 2020)
      We report on our observing campaign of the compact binary merger GW190814, detected by the Advanced LIGO and Advanced Virgo detectors on 2019 August 14. This signal has the best localization of any observed gravitational wave (GW) source, with a 90 per cent probability area of 18.5 deg(2), and an estimated distance of approximate to 240 Mpc. We obtained wide-field observations with the Deca-Degree Optical Transient Imager (DDOTI) covering 88 per cent of the probability area down to a limiting magnitude of w = 19.9 AB. Nearby galaxies within the high probability region were targeted with the Lowell Discovery Telescope (LDT), whereas promising candidate counterparts were characterized through multicolour photometry with the Reionization and Transients InfraRed (RATIR) and spectroscopy with the Gran Telescopio de Canarias (GTC). We use our optical and near-infrared limits in conjunction with the upper limits obtained by the community to constrain the possible electromagnetic counterparts associated with the merger. A gamma-ray burst seen along its jet's axis is disfavoured by the multiwavelength data set, whereas the presence of a burst seen at larger viewing angles is not well constrained. Although our observations are not sensitive to a kilonova similar to AT2017gfo, we can rule out high-mass (>0.1 M-circle dot) fast-moving (mean velocity >= 0.3c) wind ejecta for a possible kilonova associated with this merger.
    • A thirty-four billion solar mass black hole in SMSS J2157-3602, the most luminous known quasar

      Onken, Christopher A.; Bian, Fuyan; Fan, Xiaohui; Wang, Feige; Wolf, Christian; Yang, Jinyi; Univ Arizona, Steward Observ (OXFORD UNIV PRESS, 2020-08)
      From near-infrared spectroscopic measurements of the Mg II emission line doublet, we estimate the black hole (BH) mass of the quasar, SMSS J215728.21-360215.1, as being (3.4 +/- 0.6) x 10(10) M circle dot and refine the redshift of the quasar to be z = 4.692. SMSS J2157 is the most luminous known quasar, with a 3000 angstrom luminosity of (4.7 +/- 0.5) x 10(47) erg s(-1) and an estimated bolometric luminosity of 1.6 x 10(48) erg s(-1), yet its Eddington ratio is only similar to 0.4. Thus, the high luminosity of this quasar is a consequence of its extremely large BH - one of the most massive BHs at z > 4.
    • Access to RNA-sequencing data from 1,173 plant species: The 1000 Plant transcriptomes initiative (1KP)

      Carpenter, Eric J; Matasci, Naim; Ayyampalayam, Saravanaraj; Wu, Shuangxiu; Sun, Jing; Yu, Jun; Jimenez Vieira, Fabio Rocha; Bowler, Chris; Dorrell, Richard G; Gitzendanner, Matthew A; et al. (OXFORD UNIV PRESS, 2019-10-23)
      Background: The 1000 Plant transcriptomes initiative (1KP) explored genetic diversity by sequencing RNA from 1,342 samples representing 1,173 species of green plants (Viridiplantae). Findings: This data release accompanies the initiative's final/capstone publication on a set of 3 analyses inferring species trees, whole genome duplications, and gene family expansions. These and previous analyses are based on de novo transcriptome assemblies and related gene predictions. Here, we assess their data and assembly qualities and explain how we detected potential contaminations. Conclusions: These data will be useful to plant and/or evolutionary scientists with interests in particular gene families, either across the green plant tree of life or in more focused lineages.
    • Advancing an interdisciplinary framework to study seed dispersal ecology

      Beckman, Noelle G; Aslan, Clare E; Rogers, Haldre S; Kogan, Oleg; Bronstein, Judith L; Bullock, James M; Hartig, Florian; HilleRisLambers, Janneke; Zhou, Ying; Zurell, Damaris; et al. (OXFORD UNIV PRESS, 2019-08-19)
      Although dispersal is generally viewed as a crucial determinant for the fitness of any organism, our understanding of its role in the persistence and spread of plant populations remains incomplete. Generalizing and predicting dispersal processes are challenging due to context dependence of seed dispersal, environmental heterogeneity and interdependent processes occurring over multiple spatial and temporal scales. Current population models often use simple phenomenological descriptions of dispersal processes, limiting their ability to examine the role of population persistence and spread, especially under global change. To move seed dispersal ecology forward, we need to evaluate the impact of any single seed dispersal event within the full spatial and temporal context of a plant's life history and environmental variability that ultimately influences a population's ability to persist and spread. In this perspective, we provide guidance on integrating empirical and theoretical approaches that account for the context dependency of seed dispersal to improve our ability to generalize and predict the consequences of dispersal, and its anthropogenic alteration, across systems. We synthesize suitable theoretical frameworks for this work and discuss concepts, approaches and available data from diverse subdisciplines to help operationalize concepts, highlight recent breakthroughs across research areas and discuss ongoing challenges and open questions. We address knowledge gaps in the movement ecology of seeds and the integration of dispersal and demography that could benefit from such a synthesis. With an interdisciplinary perspective, we will be able to better understand how global change will impact seed dispersal processes, and potential cascading effects on plant population persistence, spread and biodiversity.
    • The AGN contribution to the UV–FIR luminosities of interacting galaxies and its role in identifying the main sequence

      Ramos Padilla, Andrés F; Ashby, M L N; Smith, Howard A; Martínez-Galarza, Juan R; Beverage, Aliza G; Dietrich, Jeremy; Higuera-G., Mario-A; Weiner, Aaron S; Univ Arizona, Dept Astron; Univ Arizona, Steward Observ (OXFORD UNIV PRESS, 2020-09-15)
      Emission from active galactic nuclei (AGNs) is known to play an important role in the evolution of many galaxies including luminous and ultraluminous systems (U/LIRGs), as well as merging systems. However, the extent, duration, and exact effects of its influence are still imperfectly understood. To assess the impact of AGNs on interacting systems, we present a spectral energy distribution (SED) analysis of a sample of 189 nearby galaxies. We gather and systematically re-reduce archival broad-band imaging mosaics from the ultraviolet to the far-infrared using data from GALEX, SDSS, 2MASS, IRAS, WISE, Spitzer, and Herschel. We use spectroscopy from Spitzer/IRS to obtain fluxes from fine-structure lines that trace star formation and AGN activity. Utilizing the SED modelling and fitting tool CIGALE, we derive the physical conditions of the interstellar medium, both in star-forming regions and in nuclear regions dominated by the AGN in these galaxies. We investigate how the star formation rates (SFRs) and the fractional AGN contributions (f(AGN)) depend on stellar mass, galaxy type, and merger stage. We find that luminous galaxies more massive than about 10(10) M-* are likely to deviate significantly from the conventional galaxy mainsequence relation. Interestingly, infrared AGN luminosity and stellar mass in this set of objects are much tighter than SFR and stellar mass. We find that buried AGNs may occupy a locus between bright starbursts and pure AGNs in the f(AGN)-[Ne v]/[Ne II] plane. We identify a modest correlation between f(AGN) and mergers in their later stages.
    • ALMA observations of atomic carbon in z ∼ 4 dusty star-forming galaxies

      Bothwell, M. S.; Aguirre, J. E.; Aravena, M.; Bethermin, M.; Bisbas, T. G.; Chapman, S. C.; De Breuck, C.; Gonzalez, A. H.; Greve, T. R.; Hezaveh, Y.; et al. (OXFORD UNIV PRESS, 2017-04-21)
      We present Atacama Large Millimeter Array [C-I](1 - 0) (rest frequency 492 GHz) observations for a sample of 13 strongly lensed dusty star-forming galaxies (DSFGs) originally discovered at 1.4 mm in a blank-field survey by the South Pole Telescope (SPT). We compare these new data with available [C-I] observations from the literature, allowing a study of the interstellar medium (ISM) properties of similar to 30 extreme DSFGs spanning a redshift range 2 < z < 5. Using the [C-I] line as a tracer of the molecular ISM, we find a mean molecular gas mass for SPT-DSFGs of 6.6 x 10(10) M-circle dot. This is in tension with gas masses derived via low-J (CO)-C-12 and dust masses; bringing the estimates into accordance requires either (a) an elevated CO-to-H-2 conversion factor for our sample of alpha(CO) similar to 2.5 and a gas-to-dust ratio similar to 200, or (b) an high carbon abundance X-CI similar to 7 x 10(-5). Using observations of a range of additional atomic and molecular lines (including [C-I], [C-II] and multiple transitions of CO), we use a modern photodissociation region code (3(D)-PDR) to assess the physical conditions (including the density, UV radiation field strength and gas temperature) within the ISM of the DSFGs in our sample. We find that the ISM within our DSFGs is characterized by dense gas permeated by strong UV fields. We note that previous efforts to characterize photodissociation region regions in DSFGs may have significantly under-estimated the density of the ISM. Combined, our analysis suggests that the ISM of extreme dusty starbursts at high redshift consists of dense, carbon- rich gas not directly comparable to the ISM of starbursts in the local Universe.
    • Amyloidogenic medin induces endothelial dysfunction and vascular inflammation through the receptor for advanced glycation endproducts

      Migrino, Raymond Q.; Davies, Hannah A.; Truran, Seth; Karamanova, Nina; Franco, Daniel A.; Beach, Thomas G.; Serrano, Geidy E.; Truong, Danh; Nikkhah, Mehdi; Madine, Jillian; et al. (OXFORD UNIV PRESS, 2017-09-01)
      Aims Medin is a common amyloidogenic protein in humans that accumulates in arteries with advanced age and has been implicated in vascular degeneration. Medin's effect on endothelial function remains unknown. The aims are to assess medin's effects on human arteriole endothelial function and identify potential mechanisms underlying medin-induced vascular injury. Methods and results Ex vivo human adipose and leptomeningeal arterioles were exposed (1 h) to medin (0.1, 1, or 5 mu M) without or with FPS-ZM1 [100 mu M, receptor for advanced glycation endproducts (RAGE)-specific inhibitor] and endothelium-dependent function (acetylcholine dilator response) and endothelium-independent function (dilator response to nitric oxide donor diethylenetriamine NONOate) were compared with baseline control. Human umbilical vein endothelial cells were exposed to medin without or with FPS-ZM1 and oxidative and nitrative stress, cell viability, and pro-inflammatory signaling measures were obtained. Medin caused impaired endothelial function (vs. baseline response: -45.2 +/- 5.1 and -35.8 +/- 7.9% in adipose and leptomeningeal arterioles, respectively, each P < 0.05). Dilator response to NONOate was not significantly changed. Medin decreased arteriole and endothelial cell nitric oxide production, increased superoxide production, reduced endothelial cell viability, proliferation, and migration. Medin increased gene and protein expression of interleukin-6 and interleukin-8 via activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF kappa B). Medin-induced endothelial dysfunction and oxidative stress were reversed by antioxidant polyethylene glycol superoxide dismutase and by RAGE inhibitor FPS-ZM1. Conclusions Medin causes human microvascular endothelial dysfunction through oxidative and nitrative stress and promotes pro-inflammatory signaling in endothelial cells. These effects appear to be mediated via RAGE. The findings represent a potential novel mechanism of vascular injury.
    • Analysing baryon acoustic oscillations in sparse spectroscopic samples via cross-correlation with dense photometry

      Patej, A; Eisenstein, D J; Univ Arizona, Steward Observ (OXFORD UNIV PRESS, 2018-07)
      We develop a formalism for measuring the cosmological distance scale from baryon acoustic oscillations (BAO) using the cross-correlation of a sparse redshift survey with a denser photometric sample. This reduces the shot noise that would otherwise affect the autocorrelation of the sparse spectroscopic map. As a proof of principle, we make the first on-sky application of this method to a sparse sample defined as the z > 0.6 tail of the Sloan Digital Sky Survey's (SDSS) BOSS/CMASS sample of galaxies and a dense photometric sample from SDSS DR9. We find a 2.8 sigma preference for the BAO peak in the cross-correlation at an effective z = 0.64, from which we measure the angular diameter distance D-M(z = 0.64) = (2418 +/- 73 Mpc)(r(s)/r(s, fid)). Accordingly, we expect that using this method to combine sparse spectroscopy with the deep, high-quality imaging that is just now becoming available will enable higher precision BAO measurements than possible with the spectroscopy alone.
    • Analysing H(z) data using two-point diagnostics

      Leaf, Kyle; Melia, Fulvio; Univ Arizona, Dept Phys; Univ Arizona, Dept Phys, Program Appl Math; Univ Arizona, Dept Astron (OXFORD UNIV PRESS, 2017-09)
      Measurements of the Hubble constantH(z) are increasingly being used to test the expansion rate predicted by various cosmological models. But the recent application of two-point diagnostics, such as Om(zi, zj) and Omh(2)(zi, zj), has produced considerable tension between Lambda CDM's predictions and several observations, with other models faring even worse. Part of this problem is attributable to the continued mixing of truly model-independent measurements using the cosmic-chronometer approach, and model-dependent data extracted from baryon acoustic oscillations. In this paper, we advance the use of two-point diagnostics beyond their current status, and introduce new variations, which we call Delta h(zi, zj), that are more useful for model comparisons. But we restrict our analysis exclusively to cosmic-chronometer data, which are truly model independent. Even for these measurements, however, we confirm the conclusions drawn by earlier workers that the data have strongly non-Gaussian uncertainties, requiring the use of both 'median' and 'mean' statistical approaches. Our results reveal that previous analyses using two-point diagnostics greatly underestimated the errors, thereby misinterpreting the level of tension between theoretical predictions and H(z) data. Instead, we demonstrate that as of today, only Einstein-de Sitter is ruled out by the two-point diagnostics at a level of significance exceeding similar to 3s. The R-h = ct universe is slightly favoured over the remaining models, including Lambda cold dark matter and Chevalier-Polarski-Linder, though all of them (other than Einstein-de Sitter) are consistent to within 1 sigma with the measured mean of the Delta h(zi, zj) diagnostics.
    • Analysis of aggregated cell-cell statistical distances within pathways unveils therapeutic-resistance mechanisms in circulating tumor cells.

      Schissler, A Grant; Li, Qike; Chen, James L; Kenost, Colleen; Achour, Ikbel; Billheimer, D Dean; Li, Haiquan; Piegorsch, Walter W; Lussier, Yves A; University of Arizona; et al. (OXFORD UNIV PRESS, 2016-06-15)
      As 'omics' biotechnologies accelerate the capability to contrast a myriad of molecular measurements from a single cell, they also exacerbate current analytical limitations for detecting meaningful single-cell dysregulations. Moreover, mRNA expression alone lacks functional interpretation, limiting opportunities for translation of single-cell transcriptomic insights to precision medicine. Lastly, most single-cell RNA-sequencing analytic approaches are not designed to investigate small populations of cells such as circulating tumor cells shed from solid tumors and isolated from patient blood samples.
    • Analysis of Copy Number Variation in the Abp Gene Regions of Two House Mouse Subspecies Suggests Divergence during the Gene Family Expansions

      Pezer, Željka; Chung, Amanda G.; Karn, Robert C.; Laukaitis, Christina M.; Univ Arizona, Coll Med, Dept Med, Tucson, AZ 85721 USA (OXFORD UNIV PRESS, 2017-06)
      The Androgen-binding protein (Abp) gene region of the mouse genome contains 64 genes, some encoding pheromones that influence assortative mating between mice from different subspecies. Using CNVnator and quantitative PCR, we explored copy number variation in this gene family in natural populations of Musmusculus domesticus (Mmd) and Musmusculus musculus (Mmm), two subspecies of house mice that form a narrow hybrid zone in Central Europe. We found that copy number variation in the center of the Abp gene region is very common in wild Mmd, primarily representing the presence/absence of the final duplications described for the mouse genome. Clustering of Mmd individuals based on this variation did not reflect their geographical origin, suggesting no population divergence in the Abp gene cluster. However, copy number variation patterns differ substantially between Mmd and other mouse taxa. Large blocks of Abp genes are absent in Mmm, Musmusculus castaneus and an outgroup, Mus spretus, although with differences in variation and breakpoint locations. Our analysis calls into question the reliance on a reference genome for interpreting the detailed organization of genes in taxa more distant from the Mmd reference genome. The polymorphic nature of the gene family expansion in all four taxa suggests that the number of Abp genes, especially in the central gene region, is not critical to the survival and reproduction of the mouse. However, Abp haplotypes of variable length may serve as a source of raw genetic material for new signals influencing reproductive communication and thus speciation of mice.
    • Analysis of the dust jet imaged by Rosetta VIRTIS-M in the coma of comet 67P/Churyumov-Gerasimenko on 2015 April 12

      Tenishev, V.; Fougere, N.; Borovikov, D.; Combi, M. R.; Bieler, A.; Hansen, K. C.; Gombosi, T. I.; Migliorini, A.; Capaccioni, F.; Rinaldi, G.; et al. (OXFORD UNIV PRESS, 2016-11-16)
      This work is a part of a more global effort aimed at understanding and interpreting in situ and remote sensing data acquired by instruments on board Rosetta. This study aims at deriving the dust mass source rate and the location of the dust jet source observed by Rosetta VIRTIS-M on 2015 April 12. The analysis is performed by means of the coupled kinetic modelling of gas and dust in the coma of comet 67P/Churyumov-Gerasimenko, which were used for calculating the coma brightness as it would be seen from the Rosetta spacecraft. The dust mass production rate and a possible location of the jet origin needed to explain the Rosetta VIRTIS-M dust brightness image were inferred by comparing the calculated brightness with VIRTIS-M data. Our analysis suggests that the dust mass production rate needed to maintain the observed jet is about 1.9 kg s(-1). According to our analysis, the location of the observed jet surface footprint is outside of the nucleus area characterized by the highest gas production rate, which suggests that gas and dust source rates are not necessarily proportional to each other across the entire nucleus surface. The inferred location of the possible jet origin is consistent with that of the observed active pits. In this paper, we show that the jet intensity is variable in time, and has a lifetime of at least 10 h.
    • Ancient DNA provides evidence of 27,000-year-old papillomavirus infection and long-term codivergence with rodents

      Larsen, Brendan B; Cole, Kenneth L; Worobey, Michael; Univ Arizona, Dept Ecol & Evolutionary Biol (OXFORD UNIV PRESS, 2018-01)
      The long-term evolutionary history of many viral lineages is poorly understood. Novel sources of ancient DNA combined with phylogenetic analyses can provide insight into the time scale of virus evolution. Here we report viral sequences from ancient North American packrat middens. We screened samples up to 27,000-years old and found evidence of papillomavirus (PV) infection in Neotoma cinerea (Bushy-tailed packrat). Phylogenetic analysis placed the PV sequences in a clade with other previously published PV sequences isolated from rodents. Concordance between the host and virus tree topologies along with a correlation in branch lengths suggests a shared evolutionary history between rodents and PVs. Based on host divergence times, PVs have likely been circulating in rodents for at least 17 million years. These results have implications for our understanding of PV evolution and for further research with ancient DNA from Neotoma middens.
    • Ancient eruptions of η Carinae: a tale written in proper motions

      Kiminki, Megan M.; Reiter, Megan; Smith, Nathan; Univ Arizona, Steward Observ (OXFORD UNIV PRESS, 2016-11-21)
      We analyse eight epochs of Hubble Space Telescope H alpha+[N ii] imaging of eta Carinae's outer ejecta. Proper motions of nearly 800 knots reveal that the detected ejecta are divided into three apparent age groups, dating to around 1250 A.D., to around 1550 A.D., and to during or shortly before the Great Eruption of the 1840s. Ejecta from these groups reside in different locations and provide a firm constraint that eta Car experienced multiple major eruptions prior to the nineteenth century. The 1250 and 1550 events did not share the same axisymmetry as the Homunculus; the 1250 event was particularly asymmetric, even one-sided. In addition, the ejecta in the S ridge, which have been associated with the Great Eruption, appear to predate the ejection of the Homunculus by several decades. We detect essentially ballistic expansion across multiple epochs. We find no evidence for large-scale deceleration of the observed knots that could power the soft X-ray shell by ploughing into surrounding material, suggesting that the observed X-rays arise instead from fast, rarefied ejecta from the 1840s overtaking the older dense knots. Early deceleration and subsequent coasting cannot explain the origin of the older outer ejecta - significant episodic mass loss prior to the nineteenth century is required. The time-scale and geometry of the past eruptions provide important constraints for any theoretical physical mechanisms driving eta Car's behaviour. Non-repeating mechanisms such as the merger of a close binary in a triple system would require additional complexities to explain the observations.