1,472 research outputs found
Infrared studies of supernova remnants with the IRAS
A comparative study of the infrared and X-ray fluxes and morphologies of supernova remnants (SNR) can yield valuable information on their evolution and on their interaction with the smbient interstellar medium (ISM)
A Tentative Detection of the Cosmic Infrared Background at 3.5 microns from COBE/DIRBE Observations
Foreground emission and scattered light from interplanetary dust (IPD)
particles and emission from Galactic stellar sources are the greatest obstacles
for determining the cosmic infrared background (CIB) from diffuse sky
measurements in the ~ 1 to 5 micron range. We use ground-based observational
limits on the K-band intensity of the CIB in conjunction with skymaps obtained
by the Diffuse Infrared Background Experiment (DIRBE) on the COBE satellite to
reexamine the limits on the CIB at 1.25, 3.5, and 4.9 microns. Adopting a CIB
intensity of 7.4 nW m-2 sr-1 at 2.2 microns, and using the 2.2 micron DIRBE
skymap from which the emission from IPD cloud has been subtracted, we create a
spatial template of the Galactic stellar contribution to the diffuse infrared
sky. This template is then used to subtract the contribution of the diffuse
Galactic stellar emission from the IPD-emission-subtracted DIRBE skymaps. The
DIRBE 100 micron data are used to estimate the small contribution of emission
from interstellar dust at 3.5 and 4.9 microns. Our method significantly reduces
the errors associated with the subtraction of Galactic starlight, leaving only
the IPD emission component as the primary obstacle for the detection of the CIB
at these wavelengths. This analysis leads to a tentative detection of the CIB
at 3.5 microns. The cosmological implications of these results are discussed in
the paper.Comment: 8 pages, AASTeX, 2 embedded EPS figures. Accepted for publication in
ApJ Letter
Cadherin-5: a biomarker for metastatic breast cancer with optimum efficacy in oestrogen receptor-positive breast cancers with vascular invasion
Background:
A glycoproteomic study has previously shown cadherin-5 (CDH5) to be a serological marker of metastatic breast cancer when both protein levels and glycosylation status were assessed. In this study we aimed to further validate the utility of CDH5 as a biomarker for breast cancer progression.
Methods:
A nested case–control study of serum samples from breast cancer patients, of which n=52 had developed a distant metastatic recurrence within 5 years post-diagnosis and n=60 had remained recurrence-free. ELISAs were used to quantify patient serum CDH5 levels and assess glycosylation by Helix pomatia agglutinin (HPA) binding. Clinicopathological, treatment and lifestyle factors associated with metastasis and elevated biomarker levels were identified.
Results:
Elevated CDH5 levels (P=0.028) and ratios of CDH5:HPA binding (P=0.007) distinguished patients with metastatic disease from those that remained metastasis-free. Multivariate analysis showed that the association between CDH5:HPA ratio and the formation of distant metastases was driven by patients with oestrogen receptor (ER+) positive cancer with vascular invasion (VI+).
Conclusions:
CDH5 levels and the CDH5 glycosylation represent biomarker tests that distinguish patients with metastatic breast cancer from those that remain metastasis-free. The test reached optimal sensitivity and specificity in ER-positive cancers with vascular invasion
The Resolved Near-Infrared Extragalactic Background
We present a current best estimate of the integrated near-infrared (NIR)
extragalactic background light (EBL) attributable to resolved galaxies in J, H,
and Ks. Our results in units of nW m-2 sr-1 are 11.7+5.6 -2.6 in J, 11.5+4.5
-1.5 in H and 10.0+2.8 -0.8 in Ks. We derive these new limits by combining our
deep wide-field NIR photometry from five widely separated fields with other
studies from the literature to create a galaxy counts sample that is highly
complete and has good counting statistics out to JHKs ~ 27-28. As part of this
effort we present new ultradeep Ks-band galaxy counts from 22 hours of
observations with the Multi Object Infrared Camera and Spectrograph (MOIRCS)
instrument on the Subaru Telescope. We use this MOIRCS Ks-band mosaic to
estimate the total missing flux from sources beyond our detection limits. Our
new limits to the NIR EBL are in basic agreement with, but 10 - 20% higher than
previous estimates, bringing them into better agreement with estimates of the
total NIR EBL (resolved + unresolved sources) obtained from TeV gamma-ray
opacity measurements and recent direct measurements of the total NIR EBL. We
examine field to field variations in our photometry to show that the integrated
light from galaxies is isotropic to within uncertainties, consistent with the
expected large-scale isotropy of the EBL. Our data also allow for a robust
estimate of the NIR light from Galactic stars, which we find to be 14.7 +/- 2.4
in J, 10.1 +/- 1.9 in H and 7.6 +/- 1.8 in Ks in units of nW m-2 sr-1.Comment: Accepted to Ap
Properties and Spatial Distribution of Dust Emission in the Crab Nebula
The nature and quantity of dust produced in supernovae (SNe) is still poorly understood. Recent IR observations of freshly-formed dust in supernova remnants (SNRs) have yielded significantly lower dust masses than predicted by theoretical models and observations high-redshift galaxies. The Crab Nebula's pulsar wind is thought to be sweeping up freshly-formed SN dust along with the SN ejecta. The evidence for this dust was found in the form of an IR bump in the integrated spectrum of the Crab and in extinction against the synchrotron nebula that revealed the presence of dust in the filament cores. We present the first spatially-resolved emission spectra of dust in the Crab Nebula acquired with the Spitzer Space Telescope. The IR spectra are dominated by synchrotron emission and show forbidden line emission from both sides of the expanding nebula, including emission from [S III], [Si II], [Ne II], [Ne III], [Ne V], [Ar III], [Ar V], [Fe II], and [Ni II]. We extrapolated a synchrotron spectral data cube from the Spitzer 3.6 and 4.5 micron images, and subtracted this contribution from our 15-40 micron spectral data to produce a map of the residual continuum emission from dust. The emission appears to be concentrated along the ejecta filaments and is well described by astronomical silicates at an average temperature of 65 K. The estimated mass of dust in the Crab Nebula is 0.008 solar masses
Rapid formation of large dust grains in the luminous supernova SN 2010jl
The origin of dust in galaxies is still a mystery. The majority of the
refractory elements are produced in supernova explosions but it is unclear how
and where dust grains condense and grow, and how they avoid destruction in the
harsh environments of star-forming galaxies. The recent detection of 0.1-0.5
solar masses of dust in nearby supernova remnants suggests in situ dust
formation, while other observations reveal very little dust in supernovae the
first few years after explosion. Observations of the bright SN 2010jl have been
interpreted as pre-existing dust, dust formation or no dust at all. Here we
report the rapid (40-240 days) formation of dust in its dense circumstellar
medium. The wavelength dependent extinction of this dust reveals the presence
of very large (> 1 micron) grains, which are resistant to destructive
processes. At later times (500-900 days), the near-IR thermal emission shows an
accelerated growth in dust mass, marking the transition of the supernova from a
circumstellar- to an ejecta-dominated source of dust. This provides the link
between the early and late dust mass evolution in supernovae with dense
circumstellar media.Comment: 62 pages, 13 figures, 1 table. Author version of the Letter to
Nature, published online July 9 2014 (Nature, 511, 7509, pp. 326-329 (2014)),
prior to the final editorial changes to conform to Journal style; includes
Methods and Extended Data Figures and the Supplementary Information. See
published version
http://www.nature.com/nature/journal/v511/n7509/full/nature13558.htm
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