5,607 research outputs found
Improvement of the Rotation Arch of the Posterior Interosseous Pedicle Flap Preserving Both Reverse Posterior and Anterior Interosseous Vascular Sources.
Abstract
PURPOSE:
The reverse posterior interosseous artery flap has several advantages, not sacrificing any major blood vessel, but its relatively short pedicle limits the use to cover defects up to the metacarpophalangeal joint. Our purpose is to demonstrate that the ligature of the anterior interosseous artery (AIA), proximal to the communicating branch with the posterior interosseous artery, leads to an improved flap rotation arch, preserving both vascular sources.
METHODS:
Sixteen fresh cadavers with latex perfusion were analyzed before and after our technique of elongation, and the so-obtained measures were standardized in "percentage of elongation of the pedicle." Eight patient with the loss of substance at the dorsal aspect of the hand have been treated with this technique, and results were evaluated in terms of flap survival and complication rates.
RESULTS:
The medium length of the pedicle in the normal flap was 10.8\u2009cm, and after the section of the AIA, the medium length of the pedicle was 13.6\u2009cm with a medium increase of 2.8\u2009cm. It means a medium increase of 24% of the length of the pedicle. In all patients treated, full coverage of the defect was obtained, and we did not experience major complications.
CONCLUSIONS:
This anatomical study supported by our clinical experience demonstrates that the use of the variant described above permits to reach more distal part of the hand without being afraid to stretch the pedicle because of the connection with the anastomotic arcades of the AIA at the wrist reducing the risk of ischemia of the flap
The V_c-sigma_c relation in high and low surface brightness galaxies
We investigate the relation between the asymptotic circular velocity, V_c,
and the central stellar velocity dispersion, sigma_c, in galaxies. We consider
a new sample of high surface brightness spiral galaxies (HSB), low surface
brightness spiral galaxies (LSB), and elliptical galaxies with HI-based V_c
measurements. We find that: 1) elliptical galaxies with HI measurements fit
well within the relation; 2) a linear law can reproduce the data as well as a
power law (used in previous works) even for galaxies with sigma_c < 70 km/s; 3)
LSB galaxies, considered for the first time with this respect, seem to behave
differently, showing either larger V_c values or smaller sigma_c values.Comment: 2 pages, 2 figures, to appear in Proc. IAU Symp. 222, "The Interplay
among Black Holes, Stars and ISM in Galactic Nuclei" eds. Th. Storchi
Bergmann, L.C. Ho & H.R. Schmitt (Cambridge University Press
The Black Hole Mass of Abell 1836-BCG and Abell 3565-BCG
Two brightest cluster galaxies (BCGs), namely Abell 1836-BCG and Abell
3565-BCG, were observed with the Advanced Camera for Surveys (ACS) and the
Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space
Telescope. By modeling the available photometric and kinematic data, it
resulted that the mass of Abell 1836-BCG and Abell 3565-BCG are
M_bh=4.8(+0.8,-0.7)x10^9 M_sun and M_bh=1.3(+0.3,-0.4)x10^9 M_sun at 1 sigma
confidence level, respectively.Comment: 4 pages, 3 figures, Mem SAIt in press, Proceedings of the 51st Annual
Meeting of the Italian Astronomical Society, Florence, April 17-20, 200
The Infrared Telescope Facility (IRTF) spectral library: spectral diagnostics for cool stars
The near-infrared (NIR) wavelength range offers some unique spectral
features, and it is less prone to the extinction than the optical one.
Recently, the first flux calibrated NIR library of cool stars from the NASA
Infrared Telescope Facility (IRTF) have become available, and it has not been
fully exploited yet. We want to develop spectroscopic diagnostics for stellar
physical parameters based on features in the wavelength range 1-5 micron. In
this work we test the technique in the I and K bands. The study of the Y, J, H,
and L bands will be presented in the following paper. An objective method for
semi-empirical definition of spectral features sensitive to various physical
parameters is applied to the spectra. It is based on sensitivity map--i.e.,
derivative of the flux in the spectra with respect to the stellar parameters at
a fixed wavelength. New optimized indices are defined and their equivalent
widths (EWs) are measured. A number of sensitive features to the effective
temperature and surface gravity are re-identified or newly identified clearly
showing the reliability of the sensitivity map analysis. The sensitivity map
allows to identify the best bandpass limits for the line and nearby continuum.
It reliably predicts the trends of spectral features with respect to a given
physical parameter but not their absolute strengths. Line blends are easy to
recognize when blended features have different behavior with respect to some
physical stellar parameter. The use of sensitivity map is therefore
complementary to the use of indices. We give the EWs of the new indices
measured for the IRTF star sample. This new and homogeneous set of EWs will be
useful for stellar population synthesis models and can be used to get
element-by-element abundances for unresolved stellar population studies in
galaxies.Comment: 46 pages, 27 figures, accepted for publication on Astronomy and
Astrophysic
Dissecting Kinematics and Stellar Populations of Counter-Rotating Galaxies with 2-Dimensional Spectroscopy
We present a spectral decomposition technique and its applications to a
sample of galaxies hosting large-scale counter-rotating stellar disks. Our
spectral decomposition technique allows to separate and measure the kinematics
and the properties of the stellar populations of both the two counter-rotating
disks in the observed galaxies at the same time. Our results provide new
insights on the epoch and mechanism of formation of these galaxies.Comment: 4 pages, 3 figures. Contributed talk presented at the Conference
"Multi-Spin galaxies", September 30 - October 3, 2013, INAF-Astronomical
Observatory of Capodimonte, Naples, Italy. To be published in ASP Conf. Ser.,
Multi-Spin Galaxies, ed. E. Iodice & E. M. Corsini (San Francisco: ASP
A quantum computational semantics for epistemic logical operators. Part I: epistemic structures
Some critical open problems of epistemic logics can be investigated in the framework
of a quantum computational approach. The basic idea is to interpret sentences like
“Alice knows that Bob does not understand that π is irrational” as pieces of quantum information
(generally represented by density operators of convenient Hilbert spaces). Logical
epistemic operators (to understand, to know. . .) are dealt with as (generally irreversible)
quantum operations, which are, in a sense, similar to measurement-procedures. This approach
permits us to model some characteristic epistemic processes, that concern both human
and artificial intelligence. For instance, the operation of “memorizing and retrieving
information” can be formally represented, in this framework, by using a quantum teleportation
phenomenon
Injunction Against Prosecution of Divorce Actions in Other States
Aims: The formation scenario of extended counter-rotating stellar disks in galaxies is still debated. In this paper, we study the S0 galaxy IC 719 known to host two large-scale counter-rotating stellar disks in order to investigate their formation mechanism.
Methods: We exploit the large field of view and wavelength coverage of the Multi Unit Spectroscopic Explorer (MUSE) spectrograph to derive two-dimensional (2D) maps of the various properties of the counter-rotating stellar disks, such as age, metallicity, kinematics, spatial distribution, the kinematical and chemical properties of the ionized gas, and the dust map.
Results: Due to the large wavelength range, and in particular to the presence of the Calcium Triplet \u3bb\u3bb8498, 8542, 8662 \uc5 (CaT hereafter), the spectroscopic analysis allows us to separate the two stellar components in great detail. This permits precise measurement of both the velocity and velocity dispersion of the two components as well as their spatial distribution. We derived a 2D map of the age and metallicity of the two stellar components, as well as the star formation rate and gas-phase metallicity from the ionized gas emission maps.
Conclusions: The main stellar disk of the galaxy is kinematically hotter, older, thicker and with larger scale-length than the secondary disk. There is no doubt that the latter is strongly linked to the ionized gas component: they have the same kinematics and similar vertical and radial spatial distribution. This result is in favor of a gas accretion scenario over a binary merger scenario to explain the origin of counter-rotation in IC 719. One source of gas that may have contributed to the accretion process is the cloud that surrounds IC 719
Stellar populations in the bulges of isolated galaxies
open7siWe present photometry and long-slit spectroscopy for 12 S0 and spiral galaxies selected
from the Catalogue of Isolated Galaxies. The structural parameters of the sample galaxies are
derived from the Sloan Digital Sky Survey i-band images by performing a two-dimensional
photometric decomposition of the surface brightness distribution. This is assumed to be the
sum of the contribution of a Sersic bulge, an exponential disc, and a Ferrers bar characterized
by elliptical and concentric isophotes with constant ellipticity and position angles. The rotation
curves and velocity dispersion profiles of the stellar component are measured from the spectra
obtained along the major axis of galaxies. The radial profiles of the Hβ, Mg and Fe line-
strength indices are derived too. Correlations between the central values of the Mg2
and Fe line-strength indices and the velocity dispersion are found. The mean age, total metallicity
and total α/Fe enhancement of the stellar population in the centre and at the radius, where the
bulge gives the same contribution to the total surface brightness as the remaining components,
are obtained using stellar population models with variable element abundance ratios. We
identify intermediate-age bulges with solar metallicity and old bulges with a large spread in
metallicity. Most of the sample bulges display supersolar α/Fe enhancement, no gradient in
age and negative gradients of metallicity and α/Fe enhancement. These findings support a
formation scenario via dissipative collapse where environmental effects are remarkably less
important than in the assembly of bulges of galaxies in groups and clusters.openMorelli, Lorenzo; Parmiggiani, Marco; Corsini, ENRICO MARIA; Costantin, Luca; DALLA BONTA', Elena; MĂ©ndez Abreu, J.; Pizzella, AlessandroMorelli, Lorenzo; Parmiggiani, Marco; Corsini, ENRICO MARIA; Costantin, Luca; DALLA BONTA', Elena; MĂ©ndez Abreu, J.; Pizzella, Alessandr
Genus four superstring measures
A main issue in superstring theory are the superstring measures. D'Hoker and
Phong showed that for genus two these reduce to measures on the moduli space of
curves which are determined by modular forms of weight eight and the bosonic
measure. They also suggested a generalisation to higher genus. We showed that
their approach works, with a minor modification, in genus three and we
announced a positive result also in genus four. Here we give the modular form
in genus four explicitly. Recently S. Grushevsky published this result as part
of a more general approach.Comment: 7 pages. To appear in Letters in Mathematical Physic
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