270 research outputs found
Anterior cruciate ligament recostruction with bone-patellar tendon-bone autograft in Tanner 3 stage patients with open physes
Ten skeletally immature patients were treated with an arthroscopic-assisted anterior cruciate ligament
reconstruction with bone-patellar tendon bone autograft (compass, 50\u2013558; holes, 7\u20139 mm). Radiological assessments (standard radiograph), Orthopa\ua8 dische
Arbeitsgruppe Knie (OAK) score and KT 1000, were conducted on all patients, 1 year after surgery. Skeletal maturity had been reached by all patients and no complications were observed. All patients returned to their
preinjury sport level. Drilling more vertical tunnels when bone-tendon-bone autograft was chosen to avoid partial
epiphysiodesis and offers good functional and isometric results
Multiplicity of Galactic Cepheids from long-baseline interferometry I. CHARA/MIRC detection of the companion of V1334 Cygni
We aim at determining the masses of Cepheids in binary systems, as well as
their geometric distances and the flux contribution of the companions. The
combination of interferometry with spectroscopy will offer a unique and
independent estimate of the Cepheid masses. Using long-baseline interferometry
at visible and infrared wavelengths, it is possible to spatially resolve binary
systems containing a Cepheid down to milliarcsecond separations. Based on the
resulting visual orbit and radial velocities, we can then derive the
fundamental parameters of these systems, particularly the masses of the
components and the geometric distance. We therefore performed interferometric
observations of the first-overtone mode Cepheid V1334 Cyg with the CHARA/MIRC
combiner. We report the first detection of a Cepheid companion using
long-baseline interferometry. We detect the signature of a companion orbiting
V1334 Cyg at two epochs. We measure a flux ratio between the companion and the
Cepheid f = 3.10+/-0.08%, giving an apparent magnitude mH = 8.47+/-0.15mag. The
combination of interferometric and spectroscopic data have enabled the unique
determination of the orbital elements: P = 1938.6+/-1.2 days, Tp = 2 443
616.1+/-7.3, a = 8.54+/-0.51mas, i = 124.7+/-1.8{\deg}, e = 0.190+/-0.013,
{\omega} = 228.7+/-1.6{\deg}, and {\Omega} = 206.3+/-9.4{\deg}. We derive a
minimal distance d ~ 691 pc, a minimum mass for both stars of 3.6 Msol, with a
spectral type earlier than B5.5V for the companion star. Our measured flux
ratio suggests that radial velocity detection of the companion using
spectroscopy is within reach, and would provide an orbital parallax and
model-free masses.Comment: Published in A&
First visual orbit for the prototypical colliding-wind binary WR 140
Wolf-Rayet stars represent one of the final stages of massive stellar
evolution. Relatively little is known about this short-lived phase and we
currently lack reliable mass, distance, and binarity determinations for a
representative sample. Here we report the first visual orbit for WR
140(=HD193793), a WC7+O5 binary system known for its periodic dust production
episodes triggered by intense colliding winds near periastron passage. The IOTA
and CHARA interferometers resolved the pair of stars in each year from
2003--2009, covering most of the highly-eccentric, 7.9 year orbit. Combining
our results with the recent improved double-line spectroscopic orbit of Fahed
et al. (2011), we find the WR 140 system is located at a distance of 1.67 +/-
0.03 kpc, composed of a WR star with M_WR = 14.9 +/- 0.5 Msun and an O star
with M_O = 35.9 +/- 1.3 Msun. Our precision orbit yields key parameters with
uncertainties times 6 smaller than previous work and paves the way for detailed
modeling of the system. Our newly measured flux ratios at the near-infrared H
and Ks bands allow an SED decomposition and analysis of the component
evolutionary states.Comment: Complete OIFITS dataset included via Data Conservancy Projec
Performance of a large TeO2 crystal as a cryogenic bolometer in searching for neutrinoless double beta decay
Bolometers are ideal devices in the search for neutrinoless Double Beta
Decay. Enlarging the mass of individual detectors would simplify the
construction of a large experiment, but would also decrease the background per
unit mass induced by alpha-emitters located close to the surfaces and
background arising from external and internal gamma's. We present the very
promising results obtained with a 2.13 kg TeO2 crystal. This bolometer, cooled
down to a temperature of 10.5 mK in a dilution refrigerator located deep
underground in the Gran Sasso National Laboratories, represents the largest
thermal detector ever operated. The detector exhibited an energy resolution
spanning a range from 3.9 keV (at 145 keV) to 7.8 keV (at the 2615 gamma-line
of 208Tl) FWHM. We discuss the decrease in the background per unit mass that
can be achieved increasing the mass of a bolometer.Comment: 6 pages, 6 figure
Geological entropy and solute transport in heterogeneous porous media
We propose a novel approach to link solute transport behavior to the physical heterogeneity of the aquifer, which we fully characterize with two measurable parameters: the variance of the log K values ( math formula), and a new indicator (HR) that integrates multiple properties of the K field into a global measure of spatial disorder or geological entropy. From the results of a detailed numerical experiment considering solute transport in K fields representing realistic distributions of hydrofacies in alluvial aquifers, we identify empirical relationship between the two parameters and the first three central moments of the distributions of arrival times of solute particles at a selected control plane. The analysis of experimental data indicates that the mean and the variance of the solutes arrival times tend to increase with spatial disorder (i.e., HR increasing), while highly skewed distributions are observed in more orderly structures (i.e., HR decreasing) or at higher math formula. We found that simple closed-form empirical expressions of the bivariate dependency of skewness on HR and math formula can be used to predict the emergence of non-Fickian transport in K fields considering a range of structures and heterogeneity levels, some of which based on documented real aquifers. The accuracy of these predictions and in general the results from this study indicate that a description of the global variability and structure of the K field in terms of variance and geological entropy offers a valid and broadly applicable approach for the interpretation and prediction of transport in heterogeneous porous media
Toward Direct Detection of Hot Jupiters with Precision Closure Phase: Calibration Studies and First Results from the CHARA Array
Direct detection of thermal emission from nearby hot Jupiters has greatly
advanced our knowledge of extrasolar planets in recent years. Since hot Jupiter
systems can be regarded as analogs of high contrast binaries, ground-based
infrared long baseline interferometers have the potential to resolve them and
detect their thermal emission with precision closure phase - a method that is
immune to the systematic errors induced by the Earth's atmosphere. In this
work, we present closure phase studies toward direct detection of nearby hot
Jupiters using the CHARA interferometer array outfitted with the MIRC
instrument. We carry out closure phase simulations and conduct a large number
of observations for the best candidate {\upsion} And. Our experiments suggest
the method is feasible with highly stable and precise closure phases. However,
we also find much larger systematic errors than expected in the observations,
most likely caused by dispersion across different wavelengths. We find that
using higher spectral resolution modes (e.g., R=150) can significantly reduce
the systematics. By combining all calibrators in an observing run together, we
are able to roughly recalibrate the lower spectral resolution data, allowing us
to obtain upper limits of the star-planet contrast ratios of {\upsion} And b
across the H band. The data also allow us to get a refined stellar radius of
1.625\pm0.011 R\odot. Our best upper limit corresponds to a contrast ratio of
2.1\times10^3:1 with 90% confidence level at 1.52{\mu}m, suggesting that we are
starting to have the capability of constraining atmospheric models of hot
Jupiters with interferometry. With recent and upcoming improvements of
CHARA/MIRC, the prospect of detecting emission from hot Jupiters with closure
phases is promising.Comment: 30 pages, including 9 figures and 4 tables. Published in PASP in
August 201
Physical Orbit for Lambda Virginis and a Test of Stellar Evolution Models
Lambda Virginis (LamVir) is a well-known double-lined spectroscopic Am binary
with the interesting property that both stars are very similar in abundance but
one is sharp-lined and the other is broad-lined. We present combined
interferometric and spectroscopic studies of LamVir. The small scale of the
LamVir orbit (~20 mas) is well resolved by the Infrared Optical Telescope Array
(IOTA), allowing us to determine its elements as well as the physical
properties of the components to high accuracy. The masses of the two stars are
determined to be 1.897 Msun and 1.721 Msun, with 0.7% and 1.5% errors
respectively, and the two stars are found to have the same temperature of 8280
+/- 200 K. The accurately determined properties of LamVir allow comparisons
between observations and current stellar evolution models, and reasonable
matches are found. The best-fit stellar model gives LamVir a subsolar
metallicity of Z=0.0097, and an age of 935 Myr. The orbital and physical
parameters of LamVir also allow us to study its tidal evolution time scales and
status. Although currently atomic diffusion is considered to be the most
plausible cause of the Am phenomenon, the issue is still being actively debated
in the literature. With the present study of the properties and evolutionary
status of LamVir, this system is an ideal candidate for further detailed
abundance analyses that might shed more light on the source of the chemical
anomalies in these A stars.Comment: 43 Pages, 13 figures. Accepted for publication in Ap
Multiplicity of Galactic Cepheids from long-baseline interferometry. I. CHARA/MIRC detection of the companion of V1334 Cygni
This is the final version of the article. Available from the publisher via the DOI in this record.Context. More than 60% of Cepheids are in binary or multiple systems. Studying such systems could lead to a better understanding
of the age and evolution of Cepheids. These are also useful tools to estimate the mass of Cepheids, and constrain theoretical models
of their pulsation and evolution.
Aims. We aim at determining the masses of Cepheids in binary systems, as well as their geometric distances and the flux contribution
of the companions. The combination of interferometry with spectroscopy will offer a unique and independent estimate of the Cepheid
masses.
Methods. Using long-baseline interferometry at visible and infrared wavelengths, it is possible to spatially resolve binary systems
containing a Cepheid down to milliarcsecond separations. Based on the resulting visual orbit and radial velocities, we can then derive
the fundamental parameters of these systems, particularly the masses of the components and the geometric distance. We therefore
performed interferometric observations of the first-overtone mode Cepheid V1334 Cyg with the CHARA/MIRC combiner.
Results. We report the first detection of a Cepheid companion using long-baseline interferometry. We detect the signature of a
companion orbiting V1334 Cyg at two epochs. We measure a flux ratio between the companion and the Cepheid f = 3.10 ± 0.08%,
giving an apparent magnitude mH = 8.47 ± 0.15 mag. The combination of interferometric and spectroscopic data have enabled
the unique determination of the orbital elements. P = 1938.6 ± 1.2 days, Tp = 2 443 616.1 ± 7.3, a = 8.54 ± 0.51 mas, i =
124.7 ± 1.8
◦
, e = 0.190 ± 0.013, ω = 228.7 ± 1.6
◦
, and Ω = 206.3 ± 9.4
◦
. We derive a minimal distance d ∼ 691 pc, a minimum
mass for both stars of 3.6 M , with a spectral type earlier than B5.5V for the companion star. Our measured flux ratio suggests that
radial velocity detection of the companion using spectroscopy is within reach, and would provide an orbital parallax and model-free
massesThe authors would like to thank the CHARA Array and
Mount Wilson Observatory staff for their support. Research conducted at the
CHARA Array is funded by the National Science Foundation through NSF
grant AST-0908253, by Georgia State University, the W. M. Keck Foundation,
the Packard Foundation, and the NASA Exoplanet Science Institute. J.D.M.
acknowledges funding from the NSF grants AST-0707927 and AST-0807577.
W.G. and G.P. gratefully acknowledge financial support for this work from
the BASAL Centro de Astrofísica y Tecnologías Afines (CATA) PFB-06/2007.
Support from the Polish National Science Centre grant MAESTRO and the
Polish Ministry of Science grant Ideas Plus (awarded to G. P.) is also acknowledge.
This research received the support of PHASE, the high angular
resolution partnership between ONERA, Observatoire de Paris, CNRS,
and University Denis Diderot Paris 7. A.G. acknowledges support from
FONDECYT grant 3130361. LSz has been supported by the ESTEC Contract
No.4000106398/12/NL/KML. This work made use of the SIMBAD and VIZIER
astrophysical database from CDS, Strasbourg, France and the bibliographic informations
from the NASA Astrophysics Data System. This research has made
use of the Jean-Marie Mariotti Center LITpro service, co-developed by CRAL,
LAOG and FIZEAU, and SearchCal service, co-developed by FIZEAU and
LAOG/IPAG, and of CDS Astronomical Databases SIMBAD and VIZIER
A New Limit on the Neutrinoless DBD of 130Te
We report the present results of CUORICINO a cryogenic experiment on
neutrinoless double beta decay (DBD) of 130Te consisting of an array of 62
crystals of TeO2 with a total active mass of 40.7 kg. The array is framed
inside of a dilution refrigerator, heavily shielded against environmental
radioactivity and high-energy neutrons, and operated at a temperature of ~8 mK
in the Gran Sasso Underground Laboratory. Temperature pulses induced by
particle interacting in the crystals are recorded and measured by means of
Neutron Transmutation Doped thermistors. The gain of each bolometer is
stabilized with voltage pulses developed by a high stability pulse generator
across heater resistors put in thermal contact with the absorber.
The calibration is performed by means of two thoriated wires routinely
inserted in the set-up. No evidence for a peak indicating neutrinoless DBD of
130Te is detected and a 90% C.L. lower limit of 1.8E24 years is set for the
lifetime of this process. Taking largely into account the uncertainties in the
theoretical values of nuclear matrix elements, this implies an upper boud on
the effective mass of the electron neutrino ranging from 0.2 to 1.1 eV. This
sensitivity is similar to those of the 76Ge experiments.Comment: 4 pages, 2 figure
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