15,781 research outputs found
Broad Line Radio Galaxies: Jet Contribution to the nuclear X-Ray Continuum
It is shown that, for Broad Line Radio Galaxies the strength of the
non-thermal beamed radiation, when present, is always smaller than the
accretion flow by a factor < 0.7 in the 2-10 keV band. The result has been
obtained using the procedure adopted for disentangling the Flat Spectrum Radio
Quasar 3C 273 (Grandi & Palumbo 2004). Although this implies a significantly
smaller non-thermal flux in Radio Galaxies when compared to Blazars, the jet
component, if present, could be important at very high energies and thus easily
detectable with GLAST.Comment: 12 pages including 2 figures (4 files), ApJ accepte
Constraining heavy colored resonances from top-antitop quark events
Recent measurements of the top quark charge asymmetry at Tevatron disfavor
the existence of flavor universal axigluons and colorons at 2 sigmas. In this
letter we explore the possibility to reconcile the data with these models and
use the charge asymmetry and the invariant mass distribution of top-antitop
quark pair events to constrain the mass and couplings of massive color-octet
gauge bosons decaying to top quarks.Comment: 4 pages, 4 figures. References added, final version to appear in
Phys.Rev.
Density functional theory for strongly interacting electrons
We present an alternative to the Kohn-Sham formulation of density functional
theory for the ground-state properties of strongly interacting electronic
systems. The idea is to start from the limit of zero kinetic energy and
systematically expand the universal energy functional of the density in powers
of a "coupling constant" that controls the magnitude of the kinetic energy. The
problem of minimizing the energy is reduced to the solution of a strictly
correlated electron problem in the presence of an effective potential, which
plays in our theory the same role that the Kohn-Sham potential plays in the
traditional formulation. We discuss several schemes for approximating the
energy functional, and report preliminary results for low-density quantum dots.Comment: Revised version, to appear in Phys. Rev. Let
Evidence of a large scale positive rotation-metallicity correlation in the Galactic thick disk
This study is based on high quality astrometric and spectroscopic data from
the most recent releases by Gaia and APOGEE. We select thin and thick
disk red giants, in the Galactocentric (cylindrical) distance range ~kpc and within ~kpc, for which full chemo-kinematical information
is available. Radial chemical gradients, , and rotational velocity-metallicity correlations, , are re-derived firmly uncovering that the thick disk
velocity-metallicity correlation maintains its positiveness over the ~kpc
range explored. This observational result is important as it sets experimental
constraints on recent theoretical studies on the formation and evolution of the
Milky Way disk and on cosmological models of Galaxy formation.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Societ
Functional implications of minor mandibular asymmetry: clinical and digital research on a sample of healthy patients
OBJECTIVE.The aim of the study is to evaluate the influence that the mandibular asymmetry could have towards the other components of the Stomathognatic system and to further related structures from a functional point of view. MATERIALS and METHODS. A sample of 18 young asymmetric patients, in healthy status, was investigated with clinical evaluation and questionnaires and digital devices such as Electromiography, Stabilometry, T-scan and Formetric. Descriptive and quantitative statistical analysis were performed. RESULTS. ASIM electromyography index was significant only in a short percentage of the sample. Hypertonia of temporalis muscle in the same side of mandibular deviation and the cross-activation of the contralateral masseter were present. The data of the stabilometric platform showed that only 33% of patients had a load discrepancy between right and left side. All patients presented similar and limited postural anomalies during the Formetric examination. No significant results emerged from statistics . CONCLUSIONS. From the emerging data, mandibular asymmetry does not seem to be considered a potential risk factor for the development of functional anomalies both in the stomatognatic system and in the postural one. The only issue that should be considered is the condylar retrusion of the mandibular shortest side that is a possible destabilizing factor of the TMJ condyle-disc coordination
Functional implications of minor mandibular asymmetry: clinical and digital research on a sample of healthy patients
OBJECTIVE.The aim of the study is to evaluate the influence that the mandibular asymmetry could have towards the other components of the Stomathognatic system and to further related structures from a functional point of view. MATERIALS and METHODS. A sample of 18 young asymmetric patients, in healthy status, was investigated with clinical evaluation and questionnaires and digital devices such as Electromiography, Stabilometry, T-scan and Formetric. Descriptive and quantitative statistical analysis were performed. RESULTS. ASIM electromyography index was significant only in a short percentage of the sample. Hypertonia of temporalis muscle in the same side of mandibular deviation and the cross-activation of the contralateral masseter were present. The data of the stabilometric platform showed that only 33% of patients had a load discrepancy between right and left side. All patients presented similar and limited postural anomalies during the Formetric examination. No significant results emerged from statistics . CONCLUSIONS. From the emerging data, mandibular asymmetry does not seem to be considered a potential risk factor for the development of functional anomalies both in the stomatognatic system and in the postural one. The only issue that should be considered is the condylar retrusion of the mandibular shortest side that is a possible destabilizing factor of the TMJ condyle-disc coordination
Microscopic mechanism of protein cryopreservation in an aqueous solution with trehalose
In order to investigate the cryoprotective mechanism of trehalose on proteins, we use molecular dynamics computer simulations to study the microscopic dynamics of water upon cooling in an aqueous solution of lysozyme and trehalose. We find that the presence of trehalose causes global retardation of the dynamics of water. Comparing aqueous solutions of lysozyme with/without trehalose, we observe that the dynamics of water in the hydration layers close to the protein is dramatically slower when trehalose is present in the system. We also analyze the structure of water and trehalose around the lysozyme and find that the trehalose molecules form a cage surrounding the protein that contains very slow water molecules. We conclude that the transient cage of trehalose molecules that entraps and slows the water molecules prevents the crystallisation of protein hydration water upon cooling.DC, EGS, and HES thank the NSF chemistry Division for support (Grants CHE-1213217, CHE-0911389, and CHE-0908218). PG gratefully acknowledges the computational support reveived by the INFN RM3-GRID at Roma Tre University. (CHE-1213217 - NSF chemistry Division; CHE-0911389 - NSF chemistry Division; CHE-0908218 - NSF chemistry Division)Published versio
New Signatures of the Milky Way Formation in the Local Halo and Inner Halo Streamers in the Era of Gaia
We explore the vicinity of the Milky Way through the use of
spectro-photometric data from the Sloan Digital Sky Survey and high-quality
proper motions derived from multi-epoch positions extracted from the Guide Star
Catalogue II database. In order to identify and characterise streams as relics
of the Milky Way formation, we start with classifying, select, and study
subdwarfs with up to kpc away from the Sun as tracers
of the local halo system. Then, through phase-space analysis, we find
statistical evidence of five discrete kinematic overdensities among of the
fastest-moving stars, and compare them to high-resolution N-body simulations of
the interaction between a Milky-Way like galaxy and orbiting dwarf galaxies
with four representative cases of merging histories. The observed overdensities
can be interpreted as fossil substructures consisting of streamers torn from
their progenitors, such progenitors appear to be satellites on prograde and
retrograde orbits on different inclinations. In particular, of the five
detected overdensities, two appear to be associated, yelding twenty-one
additional main-sequence members, with the stream of Helmi et al. (1999) that
our analysis confirms on a high inclination prograde orbit. The three newly
identified kinematic groups could be associated with the retrograde streams
detected by Dinescu (2002) and Kepley et al. (2007), whatever their origin, the
progenitor(s) would be on retrograde orbit(s) and inclination(s) within the
range . Finally, we use our simulations to
investigate the impact of observational errors and compare the current picture
to the promising prospect of highly improved data expected from the Gaia
mission.Comment: 16 pages, 10 figures, 6 Tables. Accepted for publication in The
Astronomical Journa
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