1,688 research outputs found
On Hirschman and log-Sobolev inequalities in mu-deformed Segal-Bargmann analysis
We consider a deformation of Segal-Bargmann space and its transform. We study
L^p properties of this transform and obtain entropy-entropy inequalities
(Hirschman) and entropy-energy inequalities (log-Sobolev) that generalize the
corresponding known results in the undeformed theory.Comment: 42 pages, 3 figure
The thermonuclear production of F19 by Wolf-Rayet stars revisited
New models of rotating and non-rotating stars are computed for initial masses
between 25 and 120 Msun and for metallicities Z = 0.004, 0.008, 0.020 and 0.040
with the aim of reexamining the wind contribution of Wolf-Rayet (WR) stars to
the F19 enrichment of the interstellar medium. Models with an initial rotation
velocity vini = 300 km/s are found to globally eject less F19 than the
non-rotating models. We compare our new predictions with those of Meynet &
Arnould (2000), and demonstrate that the F19 yields are very sensitive to the
still uncertain F19(alpha,p)Ne22 rate and to the adopted mass loss rates. Using
the recommended mass loss rate values that take into account the clumping of
the WR wind and the NACRE reaction rates when available, we obtain WR F19
yields that are significantly lower than predicted by Meynet & Arnould (2000),
and that would make WR stars non-important contributors to the galactic F19
budget. In view, however, of the large nuclear and mass loss rate
uncertainties, we consider that the question of the WR contribution to the
galactic F19 remains quite largely open.Comment: 9 pages, 5 figures, accepted for publication in Astronomy &
Astrophysic
An archetype-based solution for the interoperability of computerised guidelines and electronic health records
Clinical guidelines contain recommendations based on the best empirical evidence available at the moment. There is a wide con- sensus about the benefits of guidelines and about the fact that they should be deployed through clinical information systems, making them available during consultation time. However, one of the main obstacles to this integration is still the interaction with the electronic health record. In this paper we present an archetype-based approach to solve the inter- operability problems of guideline systems, as well as to enable guideline sharing. We also describe the knowledge requirements for the develop- ment of archetype-enabled guideline systems, and then focus on the de- velopment of appropriate guideline archetypes and on the connection of these archetypes to the target electronic health record
The Millennium Run Observatory: First Light
Simulations of galaxy evolution aim to capture our current understanding as
well as to make predictions for testing by future experiments. Simulations and
observations are often compared in an indirect fashion: physical quantities are
estimated from the data and compared to models. However, many applications can
benefit from a more direct approach, where the observing process is also
simulated and the models are seen fully from the observer's perspective. To
facilitate this, we have developed the Millennium Run Observatory (MRObs), a
theoretical virtual observatory which uses virtual telescopes to `observe'
semi-analytic galaxy formation models based on the suite of Millennium Run dark
matter simulations. The MRObs produces data that can be processed and analyzed
using the standard software packages developed for real observations. At
present, we produce images in forty filters from the rest-frame UV to IR for
two stellar population synthesis models, three different models of IGM
absorption, and two cosmologies (WMAP1/7). Galaxy distributions for a large
number of mock lightcones can be `observed' using models of major ground- and
space-based telescopes. The data include lightcone catalogues linked to
structural properties of galaxies, pre-observation model images, mock telescope
images, and Source Extractor products that can all be traced back to the higher
level dark matter, semi-analytic galaxy, and lightcone catalogues available in
the Millennium database. Here, we describe our methods and announce a first
public release of simulated surveys (e.g., SDSS, CFHT-LS, GOODS, GOODS/ERS,
CANDELS, and HUDF). The MRObs browser, an online tool, further facilitates
exploration of the simulated data. We demonstrate the benefits of a direct
approach through a number of example applications (galaxy number counts in
CANDELS, clusters, morphologies, and dropout selections).Comment: MNRAS, in press. Millennium Run Observatory data products, online
tools, and more available through http://galformod.mpa-garching.mpg.de/mrobs
Indirect study of 19Ne states near the 18F+p threshold
The early E < 511 keV gamma-ray emission from novae depends critically on the
18F(p,a)15O reaction. Unfortunately the reaction rate of the 18F(p,a)15O
reaction is still largely uncertain due to the unknown strengths of low-lying
proton resonances near the 18F+p threshold which play an important role in the
nova temperature regime. We report here our last results concerning the study
of the d(18F,p)19F(alpha)15N transfer reaction. We show in particular that
these two low-lying resonances cannot be neglected. These results are then used
to perform a careful study of the remaining uncertainties associated to the
18F(p,a)15O and 18F(p,g)19Ne reaction rates.Comment: 18 pages, 8 figures. Accepted in Nuclear Physics
Stellar evolution with rotation VII: Low metallicity models and the blue to red supergiant ratio in the SMC
We calculate a grid of models with and without the effects of axial rotation
for massive stars in the range of 9 to 60 M and metallicity =
0.004 appropriate for the SMC. Remarkably, the ratios
of the angular velocity to the break-up angular
velocity grow strongly during the evolution of high mass stars, contrary to the
situation at = 0.020. The reason is that at low , mass loss is smaller
and the removal of angular momentum during evolution much weaker, also there is
an efficient outward transport of angular momentum by meridional circulation.
Thus, a much larger fraction of the stars at lower reach break-up
velocities and rotation may thus be a dominant effect at low . The models
with rotation well account for the long standing problem of the large numbers
of red supergiants observed in low galaxies, while current models with mass
loss were predicting no red supergiants. We discuss in detail the physical
effects of rotation which favour a redwards evolution in the HR diagram. The
models also predict large N enrichments during the evolution of high mass
stars. The predicted relative N-enrichments are larger at lower than solar
and this is in very good agreement with the observations for A-type supergiants
in the SMC.Comment: 18 pages, 16 figures, in press in Astronomy and Astrophysic
A Homogenous Set of Globular Cluster Relative Distances and Reddenings
We present distance modulus and reddening determinations for 72 Galactic
globular clusters from the homogeneous photometric database of Piotto et al.
(2002), calibrated to the HST flight F439W and F555W bands. The distances have
been determined by comparison with theoretical absolute magnitudes of the ZAHB.
For low and intermediate metallicity clusters, we have estimated the apparent
Zero Age Horizontal Branch (ZAHB) magnitude from the RR Lyrae level. For metal
rich clusters, the ZAHB magnitude was obtained from the fainter envelope of the
red HB. Reddenings have been estimated by comparison of the HST
colour-magnitude diagrams (CMD) with ground CMDs of low reddening template
clusters. The homogeneity of both the photometric data and the adopted
methodological approach allowed us to obtain highly accurate relative cluster
distances and reddenings. Our results are also compared with recent
compilations in the literature.Comment: 12 pages, 6 figures, accepted for publication in Astronomy &
Astrophysic
PArthENoPE: Public Algorithm Evaluating the Nucleosynthesis of Primordial Elements
We describe a program for computing the abundances of light elements produced
during Big Bang Nucleosynthesis which is publicly available at
http://parthenope.na.infn.it/. Starting from nuclear statistical equilibrium
conditions the program solves the set of coupled ordinary differential
equations, follows the departure from chemical equilibrium of nuclear species,
and determines their asymptotic abundances as function of several input
cosmological parameters as the baryon density, the number of effective
neutrino, the value of cosmological constant and the neutrino chemical
potential. The program requires commercial NAG library routines.Comment: 18 pages, 2 figures. Version accepted by Comp. Phys. Com. The code
(and an updated manual) is publicly available at
http://parthenope.na.infn.it
Prospects for asteroseismology
The observational basis for asteroseismology is being dramatically
strengthened, through more than two years of data from the CoRoT satellite, the
flood of data coming from the Kepler mission and, in the slightly longer term,
from dedicated ground-based facilities. Our ability to utilize these data
depends on further development of techniques for basic data analysis, as well
as on an improved understanding of the relation between the observed
frequencies and the underlying properties of the stars. Also, stellar modelling
must be further developed, to match the increasing diagnostic potential of the
data. Here we discuss some aspects of data interpretation and modelling,
focussing on the important case of stars with solar-like oscillations.Comment: Proc. HELAS Workshop on 'Synergies between solar and stellar
modelling', eds M. Marconi, D. Cardini & M. P. Di Mauro, Astrophys. Space
Sci., in the press Revision: correcting abscissa labels on Figs 1 and
General Synthesis Report of the Different ADS Design Status. Establishment of a Catalogue of the R&D needs
This document is a General Synthesis Report of the Different ADS Design Status being designed within the EUROTRANS Integrated Project; an FP6 European commission partially funded programme. This project had the goal to demonstrate the possibility of nuclear waste transmutation/burning in Accelerator Driven Systems (ADS) at industrial scale.The focus is on a Pb-cooled ADS for the European Facility on Industrial scale Transmuter (ETD/EFIT) with a back-up solution based on an He cooled ADS.As an intermediate step towards this industrial-scale prototype, an eXperimental Transmuter based on ADS concept (ETD/XT-ADS) able to demonstrate both the feasibility of the ADS concept and to accumulate experience when using dedicated fuel sub-assemblies or dedicated pins within a MOX fuel core has been also studied.The two machines (XT-ADS and Pb cooled EFIT) have been designed in a consistent way bringing more credibility to the potential licensing of these plants and with sufficient details to allow definition of the critical issues as regards design, safety and associated technological and basic R&D needs. The different designs fit rather well with the technical objectives fixed at the beginning of the project in consistency with the European Roadmap on ADS development.For what concerns the accelerator, the superconducting LINAC has been clearly assessed as the most suitable concept for the three reactors in particular with respect to the stringent requirements on reliability. Associated R&D needs have been identified and will be focused on critical components (injector, cryomodule) long term testing.The design of the different ADS has been performed in view of what is reasonably achievable pending the completion of R&D programmes. The way the EUROTRANS Integrated Project has been organised with other domains than the DM1 Design being specifically devoted to R&D tasks in support to the overall ETD/EFIT and ETD/XT-ADS design tasks has been helpful. The other domains were centred on the assessment of reactivity measurement techniques (DM2 ECATS), on the development of U-free dedicated fuels (DM3 AFTRA), on materials behaviour and heavy liquid metal technology (DM4 DEMETRA) and on nuclear data assessment (DM5 NUDATRA). Pending questions associated to technology gaps have been identified through the different appropriate R&D work programmes and a Catalogue of the R&D needs has been established.Finally, the work within the EUROTRANS integrated project has provided an overall assessment of the feasibility at a reasonable cost for an ADS based transmutation so that a decision can be taken to launch a detailed design and construction of the intermediate step Experimental ADS now already launched within the 7th FP programme under the name of Common Design Team (CDT)
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