3,572 research outputs found
Using a Grid-Enabled Wireless Sensor Network for Flood Management
Flooding is becoming an increasing problem. As a result there is a need to deploy more sophisticated sensor networks to detect and react to flooding. This paper outlines a demonstration that illustrates our proposed solution to this problem involving embedded wireless hardware, component based middleware and overlay networks
0103-72.6: A New Oxygen-Rich Supernova Remnant in the Small Magellanic Cloud
010372.6, the second brightest X-ray supernova remnant (SNR) in the Small
Magellanic Cloud (SMC), has been observed with the {\it Chandra X-Ray
Observatory}. Our {\it Chandra} observation unambiguously resolves the X-ray
emission into a nearly complete, remarkably circular shell surrounding bright
clumpy emission in the center of the remnant. The observed X-ray spectrum for
the central region is evidently dominated by emission from reverse shock-heated
metal-rich ejecta. Elemental abundances in this ejecta material are
particularly enhanced in oxygen and neon, while less prominent in the heavier
elements Si, S, and Fe. We thus propose that 010372.6 is a new
``oxygen-rich'' SNR, making it only the second member of the class in the SMC.
The outer shell is the limb-brightened, soft X-ray emission from the swept-up
SMC interstellar medium. The presence of O-rich ejecta and the SNR's location
within an H{\small II} region attest to a massive star core-collapse origin for
010372.6. The elemental abundance ratios derived from the ejecta suggest an
18 M progenitor star.Comment: 6 pages (ApJ emulator format), including 5 figures and 2 tables. For
high quality Figs.1,2, & 3, contact [email protected]. Accepted by the ApJ
Letter
Spitzer Imaging and Spectral Mapping of the Oxygen-Rich Supernova Remnant G292.0+1.8
We present mid-infrared continuum and emission line images of the Galactic
oxygen-rich supernova remnant (SNR) G292.0+1.8, acquired using the MIPS and IRS
instruments on the Spitzer Space Telescope. The MIPS 24 micron and 70 micron
images of G292.0+1.8 are dominated by continuum emission from a network of
filaments encircling the SNR. The morphology of the SNR, as seen in the
mid-infrared, resembles that seen in X-rays with the Chandra X-ray Observatory.
Most of the mid-infrared emission in the MIPS images is produced by
circumstellar dust heated in the non-radiative shocks around G292.0+1.8,
confirming the results of earlier mid-IR observations with AKARI. In addition
to emission from hot dust, we have also mapped atomic line emission between 14
micron and 36 micron using IRS spectral maps. The line emission is primarily
associated with the bright oxygen-rich optical knots, but is also detected from
fast-moving knots of ejecta. We confirm our earlier detection of 15-25 micron
emission characteristic of magnesium silicate dust in spectra of the
radiatively shocked ejecta. We do not detect silicon line emission from any of
the radiatively shocked ejecta in the southeast of the SNR, possibly because
that the reverse shock has not yet penetrated most of the Si-rich ejecta in
that region. This may indicate that G292.0+1.8 is less evolved in the southeast
than the rest of the SNR, and may be further evidence in favor of an asymmetric
SN explosion as proposed in recent X-ray studies of G292.0+1.8.Comment: 16 pages, 1 table, 7 figures, accepted for publication in Ap
Correction to:Responses of Lotus corniculatus to environmental change. 4: Root carbohydrate levels at defoliation and regrowth climatic conditions are major drivers of phenolic content and forage quality (Planta, (2021), 253, 2, (38), 10.1007/s00425-020-03523-x)
Experimental feasibility of measuring the gravitational redshift of light using dispersion in optical fibers
This paper describes a new class of experiments that use dispersion in
optical fibers to convert the gravitational frequency shift of light into a
measurable phase shift or time delay. Two conceptual models are explored. In
the first model, long counter-propagating pulses are used in a vertical fiber
optic Sagnac interferometer. The second model uses optical solitons in
vertically separated fiber optic storage rings. We discuss the feasibility of
using such an instrument to make a high precision measurement of the
gravitational frequency shift of light.Comment: 11 pages, 12 figure
Comprehensive Biotransformation Analysis of Phenylalanine-Tyrosine Metabolism Reveals Alternative Routes of Metabolite Clearance in Nitisinone-Treated Alkaptonuria
Metabolomic analyses in alkaptonuria (AKU) have recently revealed alternative pathways in phenylalanine-tyrosine (phe-tyr) metabolism from biotransformation of homogentisic acid (HGA), the active molecule in this disease. The aim of this research was to study the phe-tyr metabolic pathway and whether the metabolites upstream of HGA, increased in nitisinone-treated patients, also undergo phase 1 and 2 biotransformation reactions. Metabolomic analyses were performed on serum and urine from patients partaking in the SONIA 2 phase 3 international randomised-controlled trial of nitisinone in AKU (EudraCT no. 2013-001633-41). Serum and urine samples were taken from the same patients at baseline (pre-nitisinone) then at 24 and 48 months on nitisinone treatment (patients N = 47 serum; 53 urine) or no treatment (patients N = 45 serum; 50 urine). Targeted feature extraction was performed to specifically mine data for the entire complement of theoretically predicted phase 1 and 2 biotransformation products derived from phenylalanine, tyrosine, 4-hydroxyphenylpyruvic acid and 4-hydroxyphenyllactic acid, in addition to phenylalanine-derived metabolites with known increases in phenylketonuria. In total, we observed 13 phase 1 and 2 biotransformation products from phenylalanine through to HGA. Each of these products were observed in urine and two were detected in serum. The derivatives of the metabolites upstream of HGA were markedly increased in urine of nitisinone-treated patients (fold change 1.2â16.2) and increases in 12 of these compounds were directly proportional to the degree of nitisinone-induced hypertyrosinaemia (correlation coefficient with serum tyrosine = 0.2â0.7). Increases in the urinary phenylalanine metabolites were also observed across consecutive visits in the treated group. Nitisinone treatment results in marked increases in a wider network of phe-tyr metabolites than shown before. This network comprises alternative biotransformation products from the major metabolites of this pathway, produced by reactions including hydration (phase 1) and bioconjugation (phase 2) of acetyl, methyl, acetylcysteine, glucuronide, glycine and sulfate groups. We propose that these alternative routes of phe-tyr metabolism, predominantly in urine, minimise tyrosinaemia as well as phenylalanaemia
Non-uniform in vivo Expansion of Epstein-Barr Virus-Specific T-Cells Following Donor Lymphocyte Infusion for Post-transplant Lymphoproliferative Disease
X-Ray Emission from Multi-Phase Shock in the Large Magellanic Cloud Supernova Remnant N49
The supernova remnant (SNR) N49 in the Large Magellanic Cloud has been
observed with the Advanced CCD Imaging Spectrometer (ACIS) on board the {\it
Chandra X-Ray Observatory}. The superb angular resolution of the {\it
Chandra}/ACIS images resolves a point source, the likely X-ray counterpart of
soft gamma-ray repeater SGR 052666, and the diffuse filaments and knots
across the SNR. These filamentary features represent the blast wave sweeping
through the ambient interstellar medium and nearby dense molecular clouds. We
detect metal-rich ejecta beyond the main blast wave shock boundary in the
southwest of the SNR, which appear to be explosion fragments or ``bullets''
ejected from the progenitor star. The detection of strong H-like Si line
emission in the eastern side of the SNR requires multi-phase shocks in order to
describe the observed X-ray spectrum, whereas such a multi-phase plasma is not
evident in the western side. This complex spectral structure of N49 suggests
that the postshock regions toward the east of the SNR might have been reheated
by the reverse shock off the dense molecular clouds while the blast wave shock
front has decelerated as it propagates into the dense clouds. The X-ray
spectrum of the detected point-like source is continuum dominated and can be
described with a power law of 3. This provides a confirmation
that this point-like X-ray source is the counterpart of SGR 052666 in the
quiescent state.Comment: Total 22 pages (in ApJ emulater style), including 8 figures (2 color
figs). Accepted by ApJ For high quality images, contact with
[email protected]
Three-micron spectra of AGB stars and supergiants in nearby galaxies
The dependence of stellar molecular bands on the metallicity is studied using
infrared L-band spectra of AGB stars (both carbon-rich and oxygen-rich) and
M-type supergiants in the Large and Small Magellanic Clouds (LMC and SMC) and
in the Sagittarius Dwarf Spheroidal Galaxy. The spectra cover SiO bands for
oxygen-rich stars, and acetylene (C2H2), CH and HCN bands for carbon-rich AGB
stars. The equivalent width of acetylene is found to be high even at low
metallicity. The high C2H2 abundance can be explained with a high
carbon-to-oxygen (C/O) ratio for lower metallicity carbon stars. In contrast,
the HCN equivalent width is low: fewer than half of the extra-galactic carbon
stars show the 3.5micron HCN band, and only a few LMC stars show high HCN
equivalent width. HCN abundances are limited by both nitrogen and carbon
elemental abundances. The amount of synthesized nitrogen depends on the initial
mass, and stars with high luminosity (i.e. high initial mass) could have a high
HCN abundance. CH bands are found in both the extra-galactic and Galactic
carbon stars. None of the oxygen-rich LMC stars show SiO bands, except one
possible detection in a low quality spectrum. The limits on the equivalent
widths of the SiO bands are below the expectation of up to 30angstrom for LMC
metallicity. Several possible explanations are discussed. The observations
imply that LMC and SMC carbon stars could reach mass-loss rates as high as
their Galactic counterparts, because there are more carbon atoms available and
more carbonaceous dust can be formed. On the other hand, the lack of SiO
suggests less dust and lower mass-loss rates in low-metallicity oxygen-rich
stars. The effect on the ISM dust enrichment is discussed.Comment: accepted for A&
Towards a global analysis of polarized parton distributions
We present a technique for implementing in a fast way, and without any
approximations, higher-order calculations of partonic cross sections into
global analyses of parton distribution functions. The approach, which is set up
in Mellin-moment space, is particularly suited for analyses of future data from
polarized proton-proton collisions, but not limited to this case. The
usefulness and practicability of this method is demonstrated for the
semi-inclusive production of hadrons in deep-inelastic scattering and the
transverse momentum distribution of ``prompt'' photons in pp collisions, and a
case study for a future global analysis of polarized parton densities is
presented.Comment: 20 pages, LaTeX, 6 eps figures, final version to appear in PRD (minor
changes
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