2,315 research outputs found
Arthopyrenia betulicola (Arthopyreniaceae, Dothidiomycetes), an Unusual New Lichenized Fungus From High Elevations of the Southern Appalachian Mountains
The crustose pyrenolichen Arthopyrenia betulicola is described as new to science based on collections from high elevations of Great Smoky Mountains National Park in eastern North America. The species is hypothesized to be endemic to the southern Appalachian Mountains where it occurs only on the bark of mature yellow birch (Betula alleghaniensis). It is a somewhat unusual member of the genus Arthopyrenia s.l. in consistently having a conspicuous photobiont layer of Trentepohlia. It differs from A. cinchonae, with which it is allopatric, by this feature as well as in having differently shaped and narrower ascospores
Respiratory syncytial virus (RSV) attachment and nonstructural proteins modify the type I interferon response associated with suppressor of cytokine signaling (SOCS) proteins and IFN-stimulated gene-15 (ISG15)
Respiratory syncytial virus (RSV) is a major cause of severe lower airway disease in infants and young children, but no safe and effective RSV vaccine is yet available. Factors attributing to this problem are associated with an incomplete understanding of the mechanisms by which RSV modulates the host cell response to infection. In the present study, we investigate suppressor of cytokine signaling (SOCS)-1 and SOCS3 expression associated with the type I IFN and IFN-stimulated gene (ISG)-15 response following infection of mouse lung epithelial (MLE-15) cells with RSV or RSV mutant viruses lacking the G gene, or NS1 and NS2 gene deletions. Studies in MLE-15 cells are important as this cell line represents the distal bronchiolar and alveolar epithelium of mice, the most common animal model used to evaluate the host cell response to RSV infection, and exhibit morphologic characteristics of alveolar type II cells, a primary cell type targeted during RSV infection. These results show an important role for SOCS1 regulation of the antiviral host response to RSV infection, and demonstrate a novel role for RSV G protein manipulation of SOCS3 and modulation of ISG15 and IFNβ mRNA expression
Respiratory syncytial virus (RSV) attachment and nonstructural proteins modify the type I interferon response associated with suppressor of cytokine signaling (SOCS) proteins and IFN-stimulated gene-15 (ISG15)
Respiratory syncytial virus (RSV) is a major cause of severe lower airway disease in infants and young children, but no safe and effective RSV vaccine is yet available. Factors attributing to this problem are associated with an incomplete understanding of the mechanisms by which RSV modulates the host cell response to infection. In the present study, we investigate suppressor of cytokine signaling (SOCS)-1 and SOCS3 expression associated with the type I IFN and IFN-stimulated gene (ISG)-15 response following infection of mouse lung epithelial (MLE-15) cells with RSV or RSV mutant viruses lacking the G gene, or NS1 and NS2 gene deletions. Studies in MLE-15 cells are important as this cell line represents the distal bronchiolar and alveolar epithelium of mice, the most common animal model used to evaluate the host cell response to RSV infection, and exhibit morphologic characteristics of alveolar type II cells, a primary cell type targeted during RSV infection. These results show an important role for SOCS1 regulation of the antiviral host response to RSV infection, and demonstrate a novel role for RSV G protein manipulation of SOCS3 and modulation of ISG15 and IFNβ mRNA expression
The Large, Oxygen-Rich Halos of Star-Forming Galaxies Are A Major Reservoir of Galactic Metals
The circumgalactic medium (CGM) is fed by galaxy outflows and accretion of
intergalactic gas, but its mass, heavy element enrichment, and relation to
galaxy properties are poorly constrained by observations. In a survey of the
outskirts of 42 galaxies with the Cosmic Origins Spectrograph onboard the
Hubble Space Telescope, we detected ubiquitous, large (150 kiloparsec) halos of
ionized oxygen surrounding star-forming galaxies, but we find much less ionized
oxygen around galaxies with little or no star formation. This ionized CGM
contains a substantial mass of heavy elements and gas, perhaps far exceeding
the reservoirs of gas in the galaxies themselves. It is a basic component of
nearly all star-forming galaxies that is removed or transformed during the
quenching of star formation and the transition to passive evolution.Comment: This paper is part of a set of three papers on circumgalactic gas
observed with the Cosmic Origins Spectrograph on HST, to be published in
Science, together with related papers by Tripp et al. and Lehner & Howk, in
the November 18, 2011 edition. This version has not undergone final
copyediting. Please see Science online for the final printed versio
Reddening, Absorption, and Decline Rate Corrections for a Complete Sample of Type Ia Supernovae leading to a Fully Corrected Hubble Diagram to v<30,000kms-1
Photometric BVI and redshift data corrected for streaming motions are
compiled for 111 "Branch normal", 4 1991T-like, 7 1991bg-like, and 2 unusual
SNe Ia. Color excesses E(B-V)host of normal SNe Ia, due to the absorption of
the host galaxy, are derived by three independent methods leading to the
intrinsic colors at maximum of (B-V)00=-0.024, and (V-I)00=-0.265 if normalized
to a common decline rate of Dm_15=1.1. The strong correlation between redshift
absolute magnitudes (based on Ho=60), corrected only for the extrinsic Galactic
absorption, and the derived E(B-V)host leads to well determined, yet abnormal
absorption-to-reddening ratios of R_BVI=3.65, 2.65, and 1.35. Comparison with
the canonical Galactic values of 4.1, 3.1, 1.8 forces the conclusion that the
law of interstellar absorption in the path length to the SN in the host galaxy
is different from the local Galactic law. Improved correlations of the fully
corrected absolute magnitudes with host galaxy type, decline rate, and
intrinsic color are derived. The four peculiar 1991T-type SNe are significantly
overluminous as compared to Branch-normal SNe Ia. The overluminosity of the
seven 1999aa-like SNe is less pronounced. The seven 1991bg-types in the sample
constitute a separate class of SNeIa, averaging in B two magnitudes fainter
than the normal Ia. New Hubble diagrams in BVI are derived out to ~30,000kms-1
using the fully corrected magnitudes and velocities, corrected for streaming
motions. Nine solutions for the intercept magnitudes in these diagrams show
extreme stability at the 0.04 level using various subsamples of the data. The
same precepts for fully correcting SN magnitudes we shall use for the
luminosity recalibration of SNe Ia in the forthcoming final review of our HST
Cepheid-SN experiment for the Hubble constant.Comment: 49 pages, 15 figures, 8 tables, accepted for publication in the
Astrophysical Journa
A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: III. The Mass- and Environment-dependent Circumgalactic Medium
Using Hubble Space Telescope Cosmic Origins Spectrograph observations of 89
QSO sightlines through the Sloan Digital Sky Survey footprint, we study the
relationships between C IV absorption systems and the properties of nearby
galaxies as well as large-scale environment. To maintain sensitivity to very
faint galaxies, we restrict our sample to 0.0015 < z < 0.015, which defines a
complete galaxy survey to L > 0.01 L* or stellar mass log M_* > 8 Msun. We
report two principal findings. First, for galaxies with impact parameter rho <
1 rvir, C IV detection strongly depends on the luminosity/stellar mass of the
nearby galaxy. C IV is preferentially associated with galaxies with log M_* >
9.5 Msun; lower mass galaxies rarely exhibit significant C IV absorption
(covering fraction f = 9 +12-6% for 11 galaxies with log M_* < 9.5 Msun).
Second, C IV detection within the log M_* > 9.5 Msun population depends on
environment. Using a fixed-aperture environmental density metric for galaxies
with rho < 160 kpc at z < 0.055, we find that 57+/-12% (8/14) of galaxies in
low-density regions (regions with fewer than seven L > 0.15 L* galaxies within
1.5 Mpc) have affiliated C IV absorption; however, none (0/7) of the galaxies
in denser regions show C IV. Similarly, the C IV detection rate is lower for
galaxies residing in groups with dark-matter halo masses of log Mhalo > 12.5
Msun. In contrast to C IV, H I is pervasive in the CGM without regard to mass
or environment. These results indicate that C IV absorbers with log N(C IV) >
13.5 cm^-2 trace the halos of log M_* > 9.5 Msun galaxies but also reflect
larger scale environmental conditions.Comment: 26 pages, 13 figures. ApJ, in pres
Associated Absorption Lines in the Radio-Loud Quasar 3C 351: Far-Ultraviolet Echelle Spectroscopy from the Hubble Space Telescope
As one of the most luminous radio-loud quasars showing intrinsic ultraviolet
(UV) and X-ray absorption, 3C 351 provides a laboratory for studying the
kinematics and physical conditions of such ionized absorbers. We present an
analysis of the intrinsic absorption lines in the high-resolution ( 7
km/s) far-UV spectrum which was obtained from observations with the Space
Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope
(HST). The spectrum spans wavelengths from 1150 \AA to 1710 \AA, and shows
strong emission lines from O VI and Ly. Associated absorption lines are
present on the blue wings of the high-ionization emission doublets O VI
1032,1038 and N V 1238,1242, as well as the
Lyman lines through Ly. These intrinsic absorption features are
resolved into several distinct kinematic components, covering rest-frame
velocities from -40 to -2800 km/s, with respect to the systemic redshift of
. For the majority of these absorption line regions, strong
evidence of partial covering of both the background continuum source and the
BELR is found, which supports the intrinsic absorption origin and rules out the
possibility that the absorption arises in some associated cluster of galaxies.
The relationship between the far-UV absorbers and X-ray `warm' absorbers are
studied with the assistance of photoionization models. Most of the UV
associated absorption components have low values of the ionization parameter
and total hydrogen column densities, which is inconsistent with previous claims
that the UV and X-ray absorption arises in the same material. Analysis of these
components supports a picture with a wide range of ionization parameters,
temperatures, and column densities in AGN outflows.Comment: 27 pages with 5 figures, accepted by Ap
Measuring primality in numerical semigroups with embedding dimension three
Electronic version of an article published as Journal of Algebra and Its Applications, 15, 1, 2016, 1650007. DOI:10.1142/S0219498816500079 © World Scientific Publishing Company https://www.worldscientific.com/doi/abs/10.1142/S0219498816500079In this paper, we find the ω-value of the generators of any numerical semigroup with embedding dimension three. This allows us to determine all possible orderings of the ω-values of the generators. In addition, we relate the ω-value of the numerical semigroup to its catenary degree.The first and third authors received National Science Foundation support under DMS-1262897. The second author is supported by the projects MTM2010-15595, FQM-343, FQM-5849, NSF-1061366 and FEDER funds
Modeling Rare Species Distribution at the Edge: The Case for the Vulnerable Endemic Pyrenean Desman in France
The endemic Pyrenean Desman (Galemys pyrenaicus) is an elusive, rare, and vulnerable species declining over its entire and narrow range (Spain, Portugal, France, and Andorra). The principal set of conservation measures in France is a 5-years National Action Plan based on 25 conservation actions. Priority is given to update its present distribution and develop tools for predictive distribution models. We aim at building the first species distribution model and map for the northern edge of the range of the Desman and confronting the outputs of the model to target conservation efforts in the context of environmental change. Contrasting to former comparable studies, we derive a simpler model emphasizing the importance of factors linked to precipitation and not to the temperature. If temperature is one of the climate change key factors, depicted shrinkage in Desman distribution could be lower or null at the northern (French) edge suggesting thus a major role for this northern population in terms of conservation of the species. Finally, we question the applied issue of temporal and spatial transferability for such environmental favourability models when it is made at the edge of the distribution range
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