5,640 research outputs found
Effects of omalizumab therapy on allergic rhinitis: a pilot study
The use of omalizumab, a humanized monoclonal antibody able to binding Ig-E, is currently authorized only for treatment of severe bronchial asthma. The use of omalizumab in other Ig-E related diseases is off-label, although some studies have provided promising results about it. The aim of this study was to evaluate if therapy with omalizumab in patients affected by asthma and allergic rhinitis has an impact also on allergic rhinitis-related symptoms
Galaxy Cluster Shapes and Systematic Errors in H0 Measured by the Sunyaev-Zel'dovich Effect
Imaging of the Sunyaev-Zel'dovich (SZ) effect in galaxy clusters combined
with cluster plasma x-ray diagnostics can measure the cosmic distance scale to
high redshift. Projecting the inverse-Compton scattering and x-ray emission
along the cluster line-of-sight introduces systematic errors in the Hubble
constant, H0, because the true shape of the cluster is not known. I present a
study of the systematic errors in the value of H0, as determined by the x-ray
and SZ properties of theoretical samples of triaxial isothermal ``beta'' model
clusters, caused by projection effects and observer orientation. I calculate
estimates for H0 for each cluster based on their large and small apparent
angular core radii and their arithmetic mean. I demonstrate that the estimates
for H0 for a sample of 25 clusters have 99.7% confidence intervals for the mean
estimated H0 analyzing the clusters using either their large or mean angular
core radius are within 14% of the ``true'' (assumed) value of H0 (and enclose
it), for a triaxial beta model cluster sample possessing a distribution of
apparent x-ray cluster ellipticities consistent with that of observed x-ray
clusters. This limit on the systematic error in H0 caused by cluster shape
assumes that each sample beta model cluster has fixed shape; deviations from
constant shape within the clusters may introduce additional uncertainty or bias
into this result.Comment: Accepted for publication in the Astrophysical Journal, 24 March 1998;
4 pages, 2 figure
Evidence of diffusive fractal aggregation of TiO2 nanoparticles by femtosecond laser ablation at ambient conditions
The specific mechanisms which leads to the formation of fractal
nanostructures by pulsed laser deposition remain elusive despite intense
research efforts, motivated mainly by the technological interest in obtaining
tailored nanostructures with simple and scalable production methods. Here we
focus on fractal nanostructures of titanium dioxide, , a strategic
material for many applications, obtained by femtosecond laser ablation at
ambient conditions. We model the fractal formation through extensive Monte
Carlo simulations based on a set of minimal assumptions: irreversible sticking
and size independent diffusion. Our model is able to reproduce the fractal
dimensions and the area distributions of the nanostructures obtained in the
experiments for different densities of the ablated material. The comparison of
theory and experiment show that such fractal aggregates are formed after
landing of the ablated material on the substrate surface by a diffusive
mechanism. Finally we discuss the role of the thermal conductivity of the
substrate and the laser fluence on the properties of the fractal
nanostructures. Our results represent an advancement towards controlling the
production of fractal nanostructures by pulsed laser deposition.Comment: 21 page
X-raying the Star Formation History of the Universe
The current models of early star and galaxy formation are based upon the
hierarchical growth of dark matter halos, within which the baryons condense
into stars after cooling down from a hot diffuse phase. The latter is
replenished by infall of outer gas into the halo potential wells; this includes
a fraction previously expelled and preheated, due to momentum and energy fed
back by the SNe which follow the star formation. We identify such an implied
hot phase with the medium known to radiate powerful X-rays in clusters and in
groups of galaxies. We show that the amount of the hot component required by
the current star formation models is enough to be observable out to redshifts
in forthcoming deep surveys from {\it Chandra} and {\it XMM},
especially in case the star formation rate is high at such and earlier .
These X-ray emissions constitute a necessary counterpart, and will provide a
much wanted probe of the SF process itself (in particular, of the SN feedback),
to parallel and complement the currently debated data from optical and IR
observations of the young stars.Comment: 13 pages, 2 figures, accepted for publicatin in ApJ
Markov Chain Monte Carlo joint analysis of Chandra X-ray imaging spectroscopy and Sunyaev-Zeldovich Effect data
X-ray and Sunyaev-Zeldovich Effect data can be combined to determine the
distance to galaxy clusters. High-resolution X-ray data are now available from
the Chandra Observatory, which provides both spatial and spectral information,
and Sunyaev-Zeldovich Effect data were obtained from the BIMA and OVRO arrays.
We introduce a Markov chain Monte Carlo procedure for the joint analysis of
X-ray and Sunyaev-Zeldovich Effect data. The advantages of this method are the
high computational efficiency and the ability to measure simultaneously the
probability distribution of all parameters of interest, such as the spatial and
spectral properties of the cluster gas and also for derivative quantities such
as the distance to the cluster. We demonstrate this technique by applying it to
the Chandra X-ray data and the OVRO radio data for the galaxy cluster Abell
611. Comparisons with traditional likelihood-ratio methods reveal the
robustness of the method. This method will be used in follow-up papers to
determine the distances to a large sample of galaxy clusters.Comment: ApJ accepted, scheduled for ApJ 10 October 2004, v614 issue. Title
changed, added more convergence diagnostic tests, Figure 7 converted to lower
resolution for easier download, other minor change
Mechanical response of 2024-7075 aluminium alloys joined by Friction Stir Welding
none3Codice Scopus: 2-s2.0-23744450678P. Cavaliere;E. Cerri;A. SquillaceCavaliere, Pasquale Daniele; E., Cerri; A., Squillac
A Deep Chandra Observation of the Distant Galaxy Cluster MS1137.5+6625
We present results from a deep Chandra observation of MS1137.5+66, a distant
(z=0.783) and massive cluster of galaxies. Only a few similarly massive
clusters are currently known at such high redshifts; accordingly, this
observation provides much-needed information on the dynamical state of these
rare systems. The cluster appears both regular and symmetric in the X-ray
image. However, our analysis of the spectral and spatial X-ray data in
conjunction with interferometric Sunyaev-Zel'dovich effect data and published
deep optical imaging suggests the cluster has a fairly complex structure. The
angular diameter distance we calculate from the Chandra and Sunyaev-Zel'dovich
effect data assuming an isothermal, spherically symmetric cluster implies a low
value for the Hubble constant for which we explore possible explanations.Comment: 16 pages, 6 figures, submitted to Ap
- âŠ