2,031 research outputs found
Strings And Non-Topological Solitons
We have numerically calculated topological andnon-topological solitons in two
spatial dimensions with Chern-Simons term. Their quantum stability, as well as
that of the Maxwell vortex, is analyzed by means of bounce instantons which
involve three-dimensional strings and non-topological solitons.Comment: 12 pages. 5 figure
Observed Limits on Charge Exchange Contributions to the Diffuse X-ray Background
We present a high resolution spectrum of the diffuse X-ray background from
0.1 to 1 keV for a ~1 region of the sky centered at l=90, b=+60 using a
36-pixel array of microcalorimeters flown on a sounding rocket. With an energy
resolution of 11 eV FWHM below 1 keV, the spectrum's observed line ratios help
separate charge exchange contributions originating within the heliosphere from
thermal emission of hot gas in the interstellar medium. The X-ray sensitivity
below 1 keV was reduced by about a factor of four from contamination that
occurred early in the flight, limiting the significance of the results. The
observed centroid of helium-like O VII is 568+2-3 eV at 90% confidence. Since
the centroid expected for thermal emission is 568.4 eV while for charge
exchange is 564.2 eV, thermal emission appears to dominate for this line
complex, consistent with much of the high-latitude O VII emission originating
in 2-3 x 10^6 K gas in the Galactic halo. On the other hand, the observed ratio
of C VI Ly gamma to Ly alpha is 0.3+-0.2. The expected ratios are 0.04 for
thermal emission and 0.24 for charge exchange, indicating that charge exchange
must contribute strongly to this line and therefore potentially to the rest of
the ROSAT R12 band usually associated with 10^6 K emission from the Local Hot
Bubble. The limited statistics of this experiment and systematic uncertainties
due to the contamination require only >32% thermal emission for O VII and >20%
from charge exchange for C VI at the 90% confidence level. An experimental gold
coating on the silicon substrate of the array greatly reduced extraneous
signals induced on nearby pixels from cosmic rays passing through the
substrate, reducing the triggered event rate by a factor of 15 from a previous
flight of the instrument.Comment: 14 pages, 7 figures, to be published in Ap
Remodelling of biological parameters during human ageing: evidence for complex regulation in longevity and in type 2 diabetes.
Factor structure analyses have revealed the presence of specific biological
system markers in healthy humans and diseases. However, this type of approach in
very old persons and in type 2 diabetes (T2DM) is lacking. A total sample of
2,137 Italians consisted of two groups: 1,604 healthy and 533 with T2DM. Age
(years) was categorized as adults (≤65), old (66-85), oldest old (>85-98) and
centenarians (≥99). Specific biomarkers of routine haematological and biochemical
testing were tested across each age group. Exploratory factorial analysis (EFA)
by principal component method with Varimax rotation was used to identify factors
including related variables. Structural equation modelling (SEM) was applied to
confirm factor solutions for each age group. EFA and SEM identified specific
factor structures according to age in both groups. An age-associated reduction of
factor structure was observed from adults to oldest old in the healthy group
(explained variance 60.4% vs 50.3%) and from adults to old in the T2DM group
(explained variance 57.4% vs 44.2%). Centenarians showed three-factor structure
similar to those of adults (explained variance 58.4%). The inflammatory component
became the major factor in old group and was the first one in T2DM. SEM analysis
in healthy subjects suggested that the glucose levels had an important role in
the oldest old. Factorial structure change during healthy ageing was associated
with a decrease in complexity but showed an increase in variability and
inflammation. Structural relationship changes observed in healthy subjects
appeared earlier in diabetic patients and later in centenarians
Xmm-Newton Observations of the Diffuse X-ray Background
We analyzed two XMM-Newton observations in the direction of the high density,
high latitude, neutral hydrogen cloud MBM20 and of a nearby low density region
that we called the Eridanus hole. The cloud MBM20 is at a distance evaluated
between 100 and 200 pc from the Sun and its density is sufficiently high to
shield about 75% of the foreground emission in the 3/4 keV energy band.The
combination of the two observations makes possible an evaluation of the OVII
and OVIII emission both for the foreground component due to the Local
Bubble,and the background one, due primary to the galactic halo.The two
observations are in good agreement with each other and with ROSAT observations
of the same part of the sky and the OVII and OVIII fluxes are OVII=3.89+/-0.56
photons cm^-2 s^-1 sr^-1, OVIII=0.68+/-0.24 photons cm^-2 s^-1 sr^-1 for MBM20
and OVII=7.26+/-0.34 photons cm^-2 s^-1 sr^-1,OVIII=1.63+/-0.17 photons cm^-2
s^-1 sr^-1 for the Eridanus hole. The spectra are in agreement with a simple
three component model, one unabsorbed and one absorbed plasma component, and a
power law, without evidence for any strong contamination from ion exchange in
the solar system. Assuming that the two plasma components are in thermal
equilibrium we obtain a temperature of 0.096 keV for the foreground component
and 0.197 keV for the background one. Assuming the foreground component is due
solely to Local Bubble emission we obtain a lower and upper limit for the
plasma density of 0.0079 cm^-3 and 0.0095 cm^-3 and limits of 16,200 cm^-3 K
and 19,500 cm^-3 K for the plasma pressure, in good agreement with theoretical
predictions. Similarly, assuming that the absorbed plasma component is due to
Galactic halo emission, we obtain a plasma density ranging from 0.0009 cm^-3 to
0.0016 cm^-3, and a pressure ranging from 3.0*10^3 to 6.7*10^3 cm^-3 K.Comment: 31 pages, 5 figures, Accepted for publication in Ap
DXL: a sounding rocket mission for the study of solar wind charge exchange and local hot bubble X-ray emission
The Diffuse X-rays from the Local galaxy (DXL) mission is an approved
sounding rocket project with a first launch scheduled around December 2012. Its
goal is to identify and separate the X-ray emission generated by solar wind
charge exchange from that of the local hot bubble to improve our understanding
of both. With 1,000 cm2 proportional counters and grasp of about 10 cm2 sr both
in the 1/4 and 3/4 keV bands, DXL will achieve in a 5-minute flight what cannot
be achieved by current and future X-ray satellites.Comment: 15 Pages, 5 figures. Accepted for publication on Experimental
Astronom
Early
Arthritis Rheum. 2004 Dec;50(12):3934-40.
Early response to immunosuppressive therapy predicts good renal outcome in lupus nephritis: lessons from long-term followup of patients in the Euro-Lupus Nephritis Trial.
Houssiau FA, Vasconcelos C, D'Cruz D, Sebastiani GD, de Ramon Garrido E, Danieli MG, Abramovicz D, Blockmans D, Mathieu A, Direskeneli H, Galeazzi M, Gül A, Levy Y, Petera P, Popovic R, Petrovic R, Sinico RA, Cattaneo R, Font J, Depresseux G, Cosyns JP, Cervera R.
Université Catholique de Louvain, Brussels, Belgium. [email protected]
Abstract
OBJECTIVE: In the Euro-Lupus Nephritis Trial (ELNT), 90 patients with lupus nephritis were randomly assigned to a high-dose intravenous cyclophosphamide (IV CYC) regimen (6 monthly pulses and 2 quarterly pulses with escalating doses) or a low-dose IV CYC regimen (6 pulses of 500 mg given at intervals of 2 weeks), each of which was followed by azathioprine (AZA). After a median followup of 41 months, a difference in efficacy between the 2 regimens was not observed. The present analysis was undertaken to extend the followup and to identify prognostic factors.
METHODS: Renal function was prospectively assessed quarterly in all 90 patients except 5 who were lost to followup. Survival curves were derived using the Kaplan-Meier method.
RESULTS: After a median followup of 73 months, there was no significant difference in the cumulative probability of end-stage renal disease or doubling of the serum creatinine level in patients who received the low-dose IV CYC regimen versus those who received the high-dose regimen. At long-term followup, 18 patients (8 receiving low-dose and 10 receiving high-dose treatment) had developed permanent renal impairment and were classified as having poor long-term renal outcome. We demonstrated by multivariate analysis that early response to therapy at 6 months (defined as a decrease in serum creatinine level and proteinuria <1 g/24 hours) was the best predictor of good long-term renal outcome.
CONCLUSION: Long-term followup of patients from the ELNT confirms that, in lupus nephritis, a remission-inducing regimen of low-dose IV CYC followed by AZA achieves clinical results comparable with those obtained with a high-dose regimen. Early response to therapy is predictive of good long-term renal outcome.
PMID: 15593207 [PubMed - indexed for MEDLINE
The Microcalorimeter Arrays for a Rhenium Experiment (MARE): a next-generation calorimetric neutrino mass experiment
Neutrino oscillation experiments have proved that neutrinos are massive
particles, but can't determine their absolute mass scale. Therefore the
neutrino mass is still an open question in elementary particle physics. An
international collaboration is growing around the project of Microcalorimeter
Arrays for a Rhenium Experiment (MARE) for directly measuring the neutrino mass
with a sensitivity of about 0.2eV/c2. Many groups are joining their experiences
and technical expertise in a common effort towards this challenging experiment.
We discuss the different scenarios and the impact of MARE as a complement of
KATRIN.Comment: 3 pages, 1 figure Nucl. Instr. Meth. A, proceedings of LTD11
workshop, Tokyo 200
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