436 research outputs found
The Spitzer Survey of Interstellar Clouds in the Gould Belt. VI. The Auriga-California Molecular Cloud observed with IRAC and MIPS
We present observations of the Auriga-California Molecular Cloud (AMC) at
3.6, 4.5, 5.8, 8.0, 24, 70 and 160 micron observed with the IRAC and MIPS
detectors as part of the Spitzer Gould Belt Legacy Survey. The total mapped
areas are 2.5 sq-deg with IRAC and 10.47 sq-deg with MIPS. This giant molecular
cloud is one of two in the nearby Gould Belt of star-forming regions, the other
being the Orion A Molecular Cloud (OMC). We compare source counts, colors and
magnitudes in our observed region to a subset of the SWIRE data that was
processed through our pipeline. Using color-magnitude and color-color diagrams,
we find evidence for a substantial population of 166 young stellar objects
(YSOs) in the cloud, many of which were previously unknown. Most of this
population is concentrated around the LkHalpha 101 cluster and the filament
extending from it. We present a quantitative description of the degree of
clustering and discuss the fraction of YSOs in the region with disks relative
to an estimate of the diskless YSO population. Although the AMC is similar in
mass, size and distance to the OMC, it is forming about 15 - 20 times fewer
stars.Comment: (30 pages, 17 figures (2 multipage figures), accepted for publication
in ApJ
Proton and Helium Spectra from the CREAM-III Flight
Primary cosmic-ray elemental spectra have been measured with the
balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The
third CREAM payload (CREAM-III) flew for 29 days during the 2007-2008 Antarctic
season. Energies of incident particles above 1 TeV are measured with a
calorimeter. Individual elements are clearly separated with a charge resolution
of ~0.12 e (in charge units) and ~0.14 e for protons and helium nuclei,
respectively, using two layers of silicon charge detectors. The measured proton
and helium energy spectra at the top of the atmosphere are harder than other
existing measurements at a few tens of GeV. The relative abundance of protons
to helium nuclei is 9.53+-0.03 for the range of 1 TeV/n to 63 TeV/n. The ratio
is considerably smaller than other measurements at a few tens of GeV/n. The
spectra become softer above ~20 TeV. However, our statistical uncertainties are
large at these energies and more data are needed
Elemental energy spectra of cosmic rays measured by CREAM-II
We present new measurements of the energy spectra of cosmic-ray (CR) nuclei
from the second flight of the balloon-borne experiment CREAM (Cosmic Ray
Energetics And Mass). The instrument (CREAM-II) was comprised of detectors
based on different techniques (Cherenkov light, specific ionization in
scintillators and silicon sensors) to provide a redundant charge identification
and a thin ionization calorimeter capable of measuring the energy of cosmic
rays up to several hundreds of TeV. The data analysis is described and the
individual energy spectra of C, O, Ne, Mg, Si and Fe are reported up to ~ 10^14
eV. The spectral shape looks nearly the same for all the primary elements and
can be expressed as a power law in energy E^{-2.66+/-0.04}. The nitrogen
absolute intensity in the energy range 100-800 GeV/n is also measured.Comment: 4 pages, 3 figures, presented at ICRC 2009, Lodz, Polan
Measurements of cosmic-ray energy spectra with the 2nd CREAM flight
During its second Antarctic flight, the CREAM (Cosmic Ray Energetics And
Mass) balloon experiment collected data for 28 days, measuring the charge and
the energy of cosmic rays (CR) with a redundant system of particle
identification and an imaging thin ionization calorimeter. Preliminary direct
measurements of the absolute intensities of individual CR nuclei are reported
in the elemental range from carbon to iron at very high energy.Comment: 4 pages, 3 figures, presented at XV International Symposium on Very
High Energy Cosmic Ray Interactions (ISVHECRI 2008
Energy spectra of cosmic-ray nuclei at high energies
We present new measurements of the energy spectra of cosmic-ray (CR) nuclei
from the second flight of the balloon-borne experiment Cosmic Ray Energetics
And Mass (CREAM). The instrument included different particle detectors to
provide redundant charge identification and measure the energy of CRs up to
several hundred TeV. The measured individual energy spectra of C, O, Ne, Mg,
Si, and Fe are presented up to eV. The spectral shape looks
nearly the same for these primary elements and it can be fitted to an power law in energy. Moreover, a new measurement of the absolute
intensity of nitrogen in the 100-800 GeV/ energy range with smaller errors
than previous observations, clearly indicates a hardening of the spectrum at
high energy. The relative abundance of N/O at the top of the atmosphere is
measured to be (stat.)(sys.) at 800
GeV/, in good agreement with a recent result from the first CREAM flight.Comment: 32 pages, 10 figures. Accepted for publication in Astrophysical
Journa
Energy Spectra, Altitude Profiles and Charge Ratios of Atmospheric Muons
We present a new measurement of air shower muons made during atmospheric
ascent of the High Energy Antimatter Telescope balloon experiment. The muon
charge ratio mu+ / mu- is presented as a function of atmospheric depth in the
momentum interval 0.3-0.9 GeV/c. The differential mu- momentum spectra are
presented between 0.3 and about 50 GeV/c at atmospheric depths between 13 and
960 g/cm^2. We compare our measurements with other recent data and with Monte
Carlo calculations of the same type as those used in predicting atmospheric
neutrino fluxes. We find that our measured mu- fluxes are smaller than the
predictions by as much as 70% at shallow atmospheric depths, by about 20% at
the depth of shower maximum, and are in good agreement with the predictions at
greater depths. We explore the consequences of this on the question of
atmospheric neutrino production.Comment: 11 pages, 8 figures, to appear in Phys. Rev. D (2000
Inhibiting ERK Activation with CI-1040 Leads to Compensatory Upregulation of Alternate MAPKs and Plasminogen Activator Inhibitor-1 following Subtotal Nephrectomy with No Impact on Kidney Fibrosis
Extracellular-signal regulated kinase (ERK) activation by MEK plays a key role in many of the cellular processes that underlie progressive kidney fibrosis including cell proliferation, apoptosis and transforming growth factor β1-mediated epithelial to mesenchymal transition. We therefore assessed the therapeutic impact of ERK1/2 inhibition using a MEK inhibitor in the rat 5/6 subtotal nephrectomy (SNx) model of kidney fibrosis. There was a twentyfold upregulation in phospho-ERK1/2 expression in the kidney after SNx in Male Wistar rats. Rats undergoing SNx became hypertensive, proteinuric and developed progressive kidney failure with reduced creatinine clearance. Treatment with the MEK inhibitor, CI-1040 abolished phospho- ERK1/2 expression in kidney tissue and prevented phospho-ERK1/2 expression in peripheral lymphocytes during the entire course of therapy. CI-1040 had no impact on creatinine clearance, proteinuria, glomerular and tubular fibrosis, and α-smooth muscle actin expression. However, inhibition of ERK1/2 activation led to significant compensatory upregulation of the MAP kinases, p38 and JNK in kidney tissue. CI-1040 also increased the expression of plasminogen activator inhibitor-1 (PAI-1), a key inhibitor of plasmin-dependent matrix metalloproteinases. Thus inhibition of ERK1/2 activation has no therapeutic effect on kidney fibrosis in SNx possibly due to increased compensatory activation of the p38 and JNK signalling pathways with subsequent upregulation of PAI-1
Next Generation LOCAD-PTS Cartridge Development
Future astrobiology exploration missions will require rapid, point-of-use techniques for surface science experiments and contamination monitoring. The Lab-On-a-Chip Application Development (LOCAD) team is developing operational instruments that advance spaceflight technologies to molecular-based methods. Currently, LOCAD-Portable Test System (PTS) is quantifying levels of the bacterial molecule endotoxin onboard the Internatioal Space Station. Future research and development will focus on more sensitive molecular techniques that expand the number of compounds detected to include beta-glucan from fungal cell walls
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