6,364 research outputs found
Medium Modification of the Jet Properties
In the case that a dense medium is created in a heavy ions collision,
high-E_t jets are expected to be broadened by medium-modified gluon emission.
This broadening is directly related, through geometry, to the energy loss
measured in inclusive high-p_t particle suppression. We present here the
modifications of jet observables due to the presence of a medium for the case
of azimuthal jet energy distributions and k_t-differential multiplicities
inside the jets.Comment: 4 pages, 3 postscript figures. Proceedings for Quark Matter 200
Spectroscopy of blue horizontal branch stars in NGC 6656 (M22)
Recent investigations revealed very peculiar properties of blue horizontal
branch (HB) stars in \omega Centauri, which show anomalously low surface
gravity and mass compared to other clusters and to theoretical models. \omega
Centauri, however, is a very unusual object, hosting a complex mix of multiple
stellar populations with different metallicity and chemical abundances. We
measured the fundamental parameters (temperature, gravity, and surface helium
abundance) of a sample of 71 blue HB stars in M22, with the aim of clarifying
if the peculiar results found in \omega Cen are unique to this cluster. M22
also hosts multiple sub-populations of stars with a spread in metallicity,
analogous to \omega Cen. The stellar parameters were measured on low-resolution
spectra fitting the Balmer and helium lines with a grid of synthetic spectra.
From these parameters, the mass and reddening were estimated. Our results on
the gravities and masses agree well with theoretical expectations, matching the
previous measurements in three "normal" clusters. The anomalies found in \omega
Cen are not observed among our stars. A mild mass underestimate is found for
stars hotter than 14\,000 K, but an exact analogy with \omega Cen cannot be
drawn. We measured the reddening in the direction of M22 with two independent
methods, finding E(B-V)=0.35 \pm 0.02 mag, with semi-amplitude of the maximum
variation \Delta(E(B-V))=0.06 mag, and an rms intrinsic dispersion of
\sigma(E(B-V))=0.03 mag.Comment: 11 pages, 9 Postscript figure
Aspects of the Unitarized Soft Multipomeron Approach in DIS and Diffraction
We study in detail the main features of the unitarized Regge model (CFKS),
recently proposed to describe the small- domain. It takes into account a
two-component description with two types of unitarized contributions: one is
the multiple pomeron exchange contribution, interacting with the large dipole
configurations, and the other one consists of a unitarized dipole cross
section, describing the interaction with the small size dipoles. We analyze the
ratio between soft and hard pieces as a function of the virtuality, and also
compare the resulting dipole cross section to that from the saturation model.
Diffraction dissociation is also considered, showing the scaling violations in
diffractive DIS and estimating the corresponding logarithmic slope.Comment: 14 pages, 5 postscript figures. Version to be published in Eur. Phys.
J.
Religious leaders\u27 perceptions of advance care planning: a secondary analysis of interviews with Buddhist, Christian, Hindu, Islamic, Jewish, Sikh and Bahai leaders
Background: International guidance for advance care planning (ACP) supports the integration of spiritual and religious aspects of care within the planning process. Religious leadersâ perspectives could improve how ACP programs respect patientsâ faith backgrounds. This study aimed to examine: (i) how religious leaders understand and consider ACP and its implications, including (ii) how religion affects followersâ approaches to end-of-life care and ACP, and (iii) their implications for healthcare.
Methods: Interview transcripts from a primary qualitative study conducted with religious leaders to inform an ACP website, ACPTalk, were used as data in this study. ACPTalk aims to assist health professionals conduct sensitive conversations with people from different religious backgrounds. A qualitative secondary analysis conducted on the interview transcripts focussed on religious leadersâ statements related to this studyâs aims. Interview transcripts were thematically analysed using an inductive, comparative, and cyclical procedure informed by grounded theory.
Results: Thirty-five religious leaders (26 male; mean 58.6-years-old), from eight Christian and six non-Christian (Jewish, Buddhist, Islamic, Hindu, Sikh, BahĂĄâĂ) backgrounds were included. Three themes emerged which focussed on: religious leadersâ ACP understanding and experiences; explanations for religious followersâ approaches towards end-of-life care; and health professionalsâ need to enquire about how religion matters. Most leaders had some understanding of ACP and, once fully comprehended, most held ACP in positive regard. Religious followersâ preferences for end-of-life care reflected family and geographical origins, cultural traditions, personal attitudes, and religiosity and faith interpretations. Implications for healthcare included the importance of avoiding generalisations and openness to individualised and/ or standardised religious expressions of oneâs religion.
Conclusions: Knowledge of religious beliefs and values around death and dying could be useful in preparing health professionals for ACP with patients from different religions but equally important is avoidance of assumptions. Community-based initiatives, programs and faith settin
Higher-order Cartan symmetries in k-symplectic field theory
For k-symplectic Hamiltonian field theories, we study infinitesimal
transformations generated by certain kinds of vector fields which are not
Noether symmetries, but which allow us to obtain conservation laws by means of
a suitable generalization of the Noether theorem.Comment: 11 page
How sensitive are high-pt electron spectra at RHIC to heavy quark energy loss?
In nucleus-nucleus collisions, high-pt electron spectra depend on the medium
modified fragmentation of their massive quark parents, thus giving novel access
to the predicted mass hierarchy of parton energy loss. Here we calculate these
spectra in a model, which supplements the perturbative QCD factorization
formalism with parton energy loss. In general, we find - within large errors -
rough agreement between theory and data on the single inclusive electron
spectrum in pp, its nuclear modification factor, and its azimuthal anisotropy.
However, the nuclear modification factor depends on the relative contribution
of charm and bottom production, which we find to be affected by large
perturbative uncertainties. In order for electron measurements to provide a
significantly more stringent test of the expected mass hierarchy, one must then
disentangle the b- and c-decay contributions, for instance by reconstructing
the displaced decay vertices.Comment: 9 pages RevTex, 4 eps-figures, asci-file containing numerical tables
of results include
Ks1, an epithelial cell-specific gene, responds to early signals of head formation in Hydra
As a molecular marker for head specification in
Hydra, we
have cloned an epithelial cell-specific gene which responds
to early signals of head formation. The gene, designated
ks1, encodes a 217-amino acid protein lacking significant
sequence similarity to any known protein. KS1 contains a
N-terminal signal sequence and is rich in charged residues
which are clustered in several domains. ks1 is expressed in
tentacle-specific epithelial cells (battery cells) as well as in
a small fraction of ectodermal epithelial cells in the gastric
region subjacent to the tentacles. Treatment with the
protein kinase C activator 12-O-tetradecanoylphorbol-13-
acetate (TPA) causes a rapid increase in the level of ks1
mRNA in head-specific epithelial cells and also induces
ectopic ks1 expression in cells of the gastric region.
Sequence elements in the 5
Âą-flanking region of ks1 that are
related to TPA-responsive elements may mediate the TPA
inducibility of ks1 expression. The pattern of expression of
ks1 suggests that a ligand-activated diacylglycerol second
messenger system is involved in head-specific differentiation
Higher dimensional gravity invariant under the Poincare group
It is shown that the Stelle-West Grignani-Nardelli-formalism allows, both
when odd dimensions and when even dimensions are considered, constructing
actions for higher dimensional gravity invariant under local Lorentz rotations
and under local Poincar\`{e} translations. It is also proved that such actions
have the same coefficients as those obtained by Troncoso and Zanelli in ref.
Class. Quantum Grav. 17 (2000) 4451.Comment: 7 pages, Latex, accepted in Phys. Rev.
Coalescing binary systems of compact objects: Dynamics of angular momenta
The end state of a coalescing binary of compact objects depends strongly on
the final total mass M and angular momentum J. Since gravitational radiation
emission causes a slow evolution of the binary system through quasi-circular
orbits down to the innermost stable one, in this paper we examine the
corresponding behavior of the ratio J/M^2 which must be less than 1(G/c) or
about 0.7(G/c) for the formation of a black hole or a neutron star
respectively. The results show cases for which, at the end of the inspiral
phase, the conditions for black hole or neutron star formation are not
satisfied. The inclusion of spin effects leads us to a study of precession
equations valid also for the calculation of gravitational waveforms.Comment: 22 pages, AASTeX and 13 figures in PostScrip
Differential Rotation in Neutron Stars: Magnetic Braking and Viscous Damping
Diffferentially rotating stars can support significantly more mass in
equilibrium than nonrotating or uniformly rotating stars, according to general
relativity. The remnant of a binary neutron star merger may give rise to such a
``hypermassive'' object. While such a star may be dynamically stable against
gravitational collapse and bar formation, the radial stabilization due to
differential rotation is likely to be temporary. Magnetic braking and viscosity
combine to drive the star to uniform rotation, even if the seed magnetic field
and the viscosity are small. This process inevitably leads to delayed collapse,
which will be accompanied by a delayed gravitational wave burst and, possibly,
a gamma-ray burst. We provide a simple, Newtonian, MHD calculation of the
braking of differential rotation by magnetic fields and viscosity. The star is
idealized as a differentially rotating, infinite cylinder consisting of a
homogeneous, incompressible conducting gas. We solve analytically the simplest
case in which the gas has no viscosity and the star resides in an exterior
vacuum. We treat numerically cases in which the gas has internal viscosity and
the star is embedded in an exterior, low-density, conducting medium. Our
evolution calculations are presented to stimulate more realistic MHD
simulations in full 3+1 general relativity. They serve to identify some of the
key physical and numerical parameters, scaling behavior and competing
timescales that characterize this important process.Comment: 11 pages. To appear in ApJ (November 20, 2000
- âŠ