186 research outputs found
Toll-like receptor 3 in Epstein-Barr virus-associated nasopharyngeal carcinomas: consistent expression and cytotoxic effects of its synthetic ligand poly(A:U) combined to a Smac-mimetic.
published_or_final_versio
Determining the extragalactic extinction law with SALT. II. Additional sample
We present new results from an on-going programme to study the dust
extragalactic extinction law in E/S0 galaxies with dust lanes with the Southern
African Large Telescope (SALT) during its performance-verification phase. The
wavelength dependence of the dust extinction for seven galaxies is derived in
six spectral bands ranging from the near-ultraviolet atmospheric cutoff to the
near-infrared. The derivation of an extinction law is performed by fitting
model galaxies to the unextinguished parts of the image in each spectral band,
and subtracting from these the actual images. We compare our results with the
derived extinction law in the Galaxy and find them to run parallel to the
Galactic extinction curve with a mean total-to-selective extinction value of
2.71+-0.43. We use total optical extinction values to estimate the dust mass
for each galaxy, compare these with dust masses derived from IRAS measurements,
and find them to range from 10^4 to 10^7 Solar masses. We study the case of the
well-known dust-lane galaxy NGC2685 for which HST/WFPC2 data is available to
test the dust distribution on different scales. Our results imply a scale-free
dust distribution across the dust lanes, at least within ~1 arcsec (~60 pc)
regions.Comment: 11 pages, 7 figures, 3 tables. Accepted for publication in MNRAS.
R-band contour maps and B-R colour-index maps are low-resolution versions of
those used in the MNRAS versio
Two Galaxy Clusters: A3565 and A3560
We report 102 new redshifts and magnitudes for a sample of galaxies to RF ~
15.5 mag in a 2.17 deg x 2.17 deg region centered on the galaxy IC 4296, the
most luminous member of the A3565 cluster. Up to the limiting magnitude we find
29 cluster members, and measure a velocity dispersion of 228 km/s. The
estimated total mass for this system is ~ 3.0 x h**-1 10**13 Msun (where h =
H0/100 km/s/Mpc), and its dynamical properties are quite typical of poor
clusters presenting X-ray emission. We also find that galaxies with absorption
lines are more concentrated towards the center of the cluster, while systems
with emission lines are mainly located in the outer parts. The small velocity
dispersion of the cluster, coupled to the known presence of an interacting pair
of galaxies, and the large extent of the brightest cluster galaxy, could
indicate that galaxy formation through mergers may still be underway in this
system. The surveyed region also contains galaxies belonging to the Shapley
Concentration cluster A3560. Within 30 arc min of the cluster center, we detect
32 galaxies, for which we measure a velocity dispersion of 588 km/s and a mass
of ~2 x h**-1 10**14 Msun. However, because our sample is restricted to
galaxies brighter than M*, these values should be considered only as rough
estimates.Comment: 33 pages, including 6 tables and 9 postscript figures. Uses AAS Latex
macros. Postscript file and ASCII versions of Tables 4 and 6 are available at
http://www.dan.on.br/other_surveys/a3565.html. Scheduled for September 1999
issue of The Astronomical Journa
HerMES: point source catalogues from Herschel-SPIRE observations II
Key Programme on the Herschel Space Observatory. With a wedding cake survey strategy, it consists of nested fields with varying depth and area totalling ∼380 deg2. In this paper, we present deep point source catalogues extracted from Herschel-Spectral and Photometric Imaging Receiver (SPIRE) observations of all HerMES fields, except for the later addition of the 270 deg2 HerMES Large-Mode Survey (HeLMS) field. These catalogues constitute the second Data Release (DR2) made in 2013 October. A sub-set of these catalogues, which consists of bright sources extracted from Herschel-SPIRE observations completed by 2010 May 1 (covering ∼74 deg2) were released earlier in the first extensive data release in 2012 March. Two different methods are used to generate the point source catalogues, the SUSSEXTRACTOR point source extractor used in two earlier data releases (EDR and EDR2) and a new source detection and photometry method. The latter combines an iterative source detection algorithm, STARFINDER, and a De-blended SPIRE Photometry algorithm. We use end-to-end Herschel-SPIRE simulations with realistic number counts and clustering properties to characterize basic properties of the point source catalogues, such as the completeness, reliability, photometric and positional accuracy. Over 500 000 catalogue entries in HerMES fields (except HeLMS) are released to the public through the HeDAM (Herschel Database in Marseille) website (http://hedam.lam.fr/HerMES)
On the Correlations between Galaxy Properties and Supermassive Black Hole Mass
We use a large sample of upper limits and accurate estimates of supermassive
black holes masses coupled with libraries of host galaxy velocity dispersions,
rotational velocities and photometric parameters extracted from Sloan Digital
Sky Survey i-band images to establish correlations between the SMBH and host
galaxy parameters. We test whether the mass of the black hole, MBH, is
fundamentally driven by either local or global galaxy properties. We explore
correlations between MBH and stellar velocity dispersion sigma, bulge
luminosity, bulge mass Sersic index, bulge mean effective surface brightness,
luminosity of the galaxy, galaxy stellar mass, maximum circular velocity Vc,
galaxy dynamical and effective masses. We verify the tightness of the MBH-sigma
relation and find that correlations with other galaxy parameters do not yield
tighter trends. We do not find differences in the MBH-sigma relation of barred
and unbarred galaxies. The MBH-sigma relation of pseudo-bulges is also coarser
and has a different slope than that involving classical bulges. The MBH-bulge
mass is not as tight as the MBH-sigma relation, despite the bulge mass proving
to be a better proxy of MBH than bulge luminosity. We find a rather poor
correlation between MBH and Sersic index suggesting that MBH is not related to
the bulge light concentration. The correlations between MBH and galaxy
luminosity or mass are not a marked improvement over the MBH sigma relation. If
Vc is a proxy for the dark matter halo mass, the large scatter of the MBH-Vc
relation then suggests that MBH is more coupled to the baryonic rather than the
dark matter. We have tested the need for a third parameter in the MBH scaling
relations, through various linear correlations with bulge and galaxy
parameters, only to confirm that the fundamental plane of the SMBH is mainly
driven by sigma, with a small tilt due to the effective radius. (Abridged)Comment: 32 pages, 18 figures, 6 tables, accepted for publication in MNRA
Globular Clusters as Candidates for Gravitational Lenses to Explain Quasar-Galaxy Associations
We argue that globular clusters (GCs) are good candidates for gravitational
lenses in explaining quasar-galaxy associations. The catalog of associations
(Bukhmastova 2001) compiled from the LEDA catalog of galaxies (Paturel 1997)
and from the catalog of quasars (Veron-Cetty and Veron 1998) is used. Based on
the new catalog containing 8382 pairs, we show that one might expect an
increased number of GCs around irregular galaxies of types 9 and 10 from the
hypothesis that distant compact sources are gravitationally lensed by GCs in
the halos of foreground galaxies. The King model is used to determine the
central surface densities of 135 GCs in the Milky Way. The distribution of GCs
in central surface density was found to be lognormal.Comment: 22 pages, 4 figure
New insights into the star formation histories of candidate intermediate-age early-type galaxies from K'-band imaging of globular clusters
We investigate age and metallicity distributions of bright globular clusters
(GCs) in the candidate intermediate-age early-type galaxies NGC 3610, NGC 584
and NGC 3377 using a combination of new Gemini/NIRI K'-band imaging and
existing optical V,I photometry from HST data. The V-I vs I-K' colour-colour
diagram is found to break the age-metallicity degeneracy present in optical
colours, as I-K' primarily measures a populations' metallicity and is
relatively insensitive, unlike optical spectroscopy, to the effect of hot
horizontal branch (HB) stars, known to be present in massive old GCs. We derive
GCs' photometric age, Z and masses. In general, metal-poor ([Z/H]<-0.7dex) GCs
are older than more metal-rich GCs. For the most massive GCs (M>6x10^5 M_sol)
in NGC 3610 with available spectroscopic data, photometric ages are older by ~2
Gyr, and this difference is more pronounced for the metal-poor GCs. However,
photometric and spectroscopic metallicities are in good agreement. We suggest
that this indicates the presence of a hot HB in these massive clusters, which
renders spectroscopic ages from Balmer line strengths to be underestimated. To
support this suggestion we show that all Galactic GCs with M>6x10^5 M_sol
feature hot HBs, except 47 Tuc. Using the relation between the most massive GC
mass and the galaxy's SFR, we find that the galaxies' peak SFR was attained at
the epoch of the formation of the oldest (metal-poor) GCs. Age and [Z/H]
distributions of the metal-rich GCs are broad, indicating prolonged galaxy star
formation histories. The peak value of the age and [Z/H] distributions of the
GCs correlates with host galaxy integrated age and [Z/H], showing that GCs can
indeed be used as relevant proxies of the star formation histories of
galaxies.(Abridged)Comment: Accepted by MNRAS; 18 pages, 12 figures, 6 tables (v2 added
references
The role of neutrophils in the upper and lower respiratory tract during influenza virus infection of mice
BACKGROUND: Neutrophils have been shown to play a role in host defence against highly virulent and mouse-adapted strains of influenza virus, however it is not clear if an effective neutrophil response is an important factor moderating disease severity during infection with other virus strains. In this study, we have examined the role of neutrophils during infection of mice with influenza virus strain HKx31, a virus strain of the H3N2 subtype and of moderate virulence for mice, to determine the role of neutrophils in the early phase of infection and in clearance of influenza virus from the respiratory tract during the later phase of infection. METHODS: The anti-Gr-1 monoclonal antibody (mAb) RB6-8C5 was used to (i) identify neutrophils in the upper (nasal tissues) and lower (lung) respiratory tract of uninfected and influenza virus-infected mice, and (ii) deplete neutrophils prior to and during influenza virus infection of mice. RESULTS: Neutrophils were rapidly recruited to the upper and lower airways following influenza virus infection. We demonstrated that use of mAb RB6-8C5 to deplete C57BL/6 (B6) mice of neutrophils is complicated by the ability of this mAb to bind directly to virus-specific CD8+ T cells. Thus, we investigated the role of neutrophils in both the early and later phases of infection using CD8+ T cell-deficient B6.TAP-/- mice. Infection of B6.TAP-/- mice with a low dose of influenza virus did not induce clinical disease in control animals, however RB6-8C5 treatment led to profound weight loss, severe clinical disease and enhanced virus replication throughout the respiratory tract. CONCLUSION: Neutrophils play a critical role in limiting influenza virus replication during the early and later phases of infection. Furthermore, a virus strain of moderate virulence can induce severe clinical disease in the absence of an effective neutrophil response
The SAURON project. II. Sample and early results
Early results are reported from the SAURON survey of the kinematics and
stellar populations of a representative sample of nearby E, S0 and Sa galaxies.
The survey is aimed at determining the intrinsic shape of the galaxies, their
orbital structure, the mass-to-light ratio as a function of radius, the age and
metallicity of the stellar populations, and the frequency of kinematically
decoupled cores and nuclear black holes. The construction of the representative
sample is described, and its properties are illustrated. A comparison with
long-slit spectroscopic data establishes that the SAURON measurements are
comparable to, or better than, the highest-quality determinations. Comparisons
are presented for NGC 3384 and NGC 4365 where stellar velocities and velocity
dispersions are determined to a precision of 6 km/s, and the h3 and h4
parameters of the line-of-sight velocity distribution to a precision of better
than 0.02. Extraction of accurate gas emission-line intensities, velocities and
line widths from the datacubes is illustrated for NGC 5813. Comparisons with
published line-strengths for NGC 3384 and NGC 5813 reveal uncertainties of <
0.1 A on the measurements of the Hbeta, Mgb and Fe5270 indices. Integral-field
mapping uniquely connects measurements of the kinematics and stellar
populations to the galaxy morphology. The maps presented here illustrate the
rich stellar kinematics, gaseous kinematics, and line-strength distributions of
early-type galaxies. The results include the discovery of a thin, edge-on, disk
in NGC 3623, confirm the axisymmetric shape of the central region of M32,
illustrate the LINER nucleus and surrounding counter-rotating star-forming ring
in NGC 7742, and suggest a uniform stellar population in the decoupled core
galaxy NGC 5813.Comment: 20 pages, 17 figures. To be published in MNRAS. Version with full
resolution images available at
http://www.strw.leidenuniv.nl/~dynamics/Instruments/Sauron/pub_list.htm
The Updated Zwicky Catalog (UZC)
The Zwicky Catalog of galaxies (ZC), with m_Zw<=15.5mag, has been the basis
for the Center for Astrophysics (CfA) redshift surveys. To date, analyses of
the ZC and redshift surveys based on it have relied on heterogeneous sets of
galaxy coordinates and redshifts. Here we correct some of the inadequacies of
previous catalogs by providing: (1) coordinates with <~2 arcsec errors for all
of the Nuzc catalog galaxies, (2) homogeneously estimated redshifts for the
majority (98%) of the data taken at the CfA (14,632 spectra), and (3) an
estimate of the remaining "blunder" rate for both the CfA redshifts and for
those compiled from the literature. For the reanalyzed CfA data we include a
calibrated, uniformly determined error and an indication of the presence of
emission lines in each spectrum. We provide redshifts for 7,257 galaxies in the
CfA2 redshift survey not previously published; for another 5,625 CfA redshifts
we list the remeasured or uniformly re-reduced value. Among our new
measurements, Nmul are members of UZC "multiplets" associated with the original
Zwicky catalog position in the coordinate range where the catalog is 98%
complete. These multiplets provide new candidates for examination of tidal
interactions among galaxies. All of the new redshifts correspond to UZC
galaxies with properties recorded in the CfA redshift compilation known as
ZCAT. About 1,000 of our new measurements were motivated either by inadequate
signal-to-noise in the original spectrum or by an ambiguous identification of
the galaxy associated with a ZCAT redshift. The redshift catalog we include
here is ~96% complete to m_Zw<=15.5, and ~98% complete (12,925 galaxies out of
a total of 13,150) for the RA(1950) ranges [20h--4h] and [8h--17h] and
DEC(1950) range [-2.5d--50d]. (abridged)Comment: 34 pp, 7 figs, PASP 1999, 111, 43
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