650 research outputs found
Effective temperature and Gilbert damping of a current-driven localized spin
Starting from a model that consists of a semiclassical spin coupled to two
leads we present a microscopic derivation of the Langevin equation for the
direction of the spin. For slowly-changing direction it takes on the form of
the stochastic Landau-Lifschitz-Gilbert equation. We give expressions for the
Gilbert damping parameter and the strength of the fluctuations, including their
bias-voltage dependence. At nonzero bias-voltage the fluctuations and damping
are not related by the fluctuation-dissipation theorem. We find, however, that
in the low-frequency limit it is possible to introduce a voltage-dependent
effective temperature that characterizes the fluctuations in the direction of
the spin, and its transport-steady-state probability distribution function.Comment: 8 pages, 2 figures. v2: published versio
A Novel Technique for Risk Calculation of Anastomotic Leakage after Thoracoscopic Repair for Esophageal Atresia with Distal Fistula
Purpose: This study was designed to determine the risk of
anastomotic leakage after thoracoscopic repair for esophageal
atresia by digitally measuring the length of the
proximal esophagus and distance of carina to proximal
esophagus.
Methods: With the use of Picture Archiving and Communication
System (PACS), the length of the proximal
esophagus from the top of the first thoracic vertebra was
measured on the preoperative chest x-ray, as well as the
distance from the carina to the proximal esophagus. The
chest x-rays of 27 neonates, born with esophageal atresia
with distal fistula, were examined. Furthermore, the tapes
from the procedures were reviewed. Statistical analysis was
performed with the t test for equality of means by using
SPSS® 12.0.1 for Windows.
Results: Both groups were comparable, and there was a
statistical significant difference in both length of the
proximal esophagus (p<0.023) and distance of carina to
proximal esophagus (p<0.022) in patients who did and
did not leak postoperatively. There seems to be a tendency
toward a shorter proximal esophagus in recent years that
was not obvious earlier.
Conclusions: The digital measurement of the length of the
proximal esophagus (M<7 mm) and distance of carina to
proximal esophagus (M<13.5 mm) with the use of PACS
gives a good risk calculation for postoperative leakage
Volvulus as a complication of chronic intestinal pseudo-obstruction syndrome
Chronic intestinal pseudo-obstruction syndrome (CIPS) is a severe motility disorder of the gastrointestinal tract that presents with continuous or recurrent symptoms and signs of intestinal obstruction without evidence of a structural lesion occluding the intestinal lumen. Mechanical obstruction might occur in these patients as well but is typically difficult to distinguish from an exacerbation of CIPS. We report two pediatric cases in which mechanical obstruction by volvulus mimicked an exacerbation of CIPS, requiring surgical intervention. Conclusion: Awareness of the possibility of true mechanical obstruction in CIPS patients during an exacerbation episode is needed, as this is a severe condition and usually requires surgical intervention
Broadly neutralizing antibodies abrogate established hepatitis C virus infection
In most exposed individuals, hepatitis C virus (HCV) establishes a chronic infection; this long-term infection in turn contributes to the development of liver diseases such as cirrhosis and hepatocellular carcinoma. The role of antibodies directed against HCV in disease progression is poorly understood. Neutralizing antibodies (nAbs) can prevent HCV infection in vitro and in animal models. However, the effects of nAbs on an established HCV infection are unclear. We demonstrate that three broadly nAbs—AR3A, AR3B, and AR4A—delivered with adeno-associated viral vectors can confer protection against viral challenge in humanized mice. Furthermore, we provide evidence that nAbs can abrogate an ongoing HCV infection in primary hepatocyte cultures and in a human liver chimeric mouse model. These results showcase a therapeutic approach to interfere with HCV infection by exploiting a previously unappreciated need for HCV to continuously infect new hepatocytes to sustain a chronic infection
Complications in pulmonary vein isolation in the Netherlands Heart Registration differ with sex and ablation technique
Aims Pulmonary vein isolation (PVI) has become a cornerstone of the invasive treatment of atrial fibrillation. Severe complications are reported in 1-3% of patients. This study aims to compare complications and follow-up outcome of PVI in patients with atrial fibrillation. Methods and results The data were extracted from the Netherlands Heart Registration. Procedural and follow-up outcomes in patients treated with conventional radiofrequency (C-RF), multielectrode phased RF (Ph-RF), or cryoballoon (CB) ablation from 2012 to 2017 were compared. Subgroup analysis was performed to identify variables associated with complications and repeat ablations. In total, 13 823 patients (69% male) were included. The reported complication incidence was 3.6%. Patients treated with C-RF developed more cardiac tamponades (C-RF 0.8% vs. Ph-RF 0.3% vs. CB 0.3%, P Conclusion The reported complication rate during PVI was low. Patients treated with C-RF ablation were more likely to develop cardiac tamponades and vascular complications. Female sex was associated with more cardiac tamponade and bleeding complications
The DEEP Groth Strip Galaxy Redshift Survey. VIII. The Evolution of Luminous Field Bulges at Redshift z ~ 1
We present a sample of over 50 luminous field bulges (including ellipticals)
found in the Groth Strip Survey (GSS), with 0.73< z < 1.04 and with bulge
magnitudes I <= 23. The exponential disk light is removed via decomposition of
HST images using GIM2D. We find that 85% of these bulges are nearly as red as
local E/S0's and have a shallow slope and a small color dispersion in the
color-luminosity relation, suggesting roughly coeval formation. The surface
brightnesses of these bulges are about 1 mag higher than local bulges. These
results are explained adopting a "drizzling" scenario where a metal-rich early
formation is later polluted by small amounts of additional star formation.
Almost all disks have the same or bluer colors than their accompanying bulges,
regardless of the bulge-disk ratio and bulge luminosity, as expected from
semi-analytic hierarchical galaxy formation models. We present evidence that
the few blue bulge candidates are not likely to be genuine blue ellipticals or
bulges. Our deeper, more extensive, and less disk-contaminated observations
challenge prior claims that 30% to 50% of field bulges or ellipticals are in a
blue, star-forming phase at z < 1. We conclude that field bulges and
ellipticals at z ~ 1, like luminous early- type cluster galaxies at the same
redshift, are already dominated by metal-rich, old stellar populations that
have been fading from a formation epoch earlier than z ~ 1.5. (abridged)Comment: ApJS accepted, 106 pages, 10 figures. Figure 14 in JPEG format. Full
version available at http://deep.ucolick.org/publications.htm
Ultimate precision in cosmic-ray radio detection - The SKA
As of 2023, the low-frequency part of the Square Kilometre Array will go online in Australia. It will constitute the largest and most powerful low-frequency radio-astronomical observatory to date, and will facilitate a rich science programme in astronomy and astrophysics. With modest engineering changes, it will also be able to measure cosmic rays via the radio emission from extensive air showers. The extreme antenna density and the homogeneous coverage provided by more than 60,000 antennas within an area of one km 2 will push radio detection of cosmic rays in the energy range around 10 17 eV to ultimate precision, with superior capabilities in the reconstruction of arrival direction, energy, and an expected depth-of-shower-maximum resolution of < 10 g/cm 2
Design and rationale of DUTCH-AF:a prospective nationwide registry programme and observational study on long-term oral antithrombotic treatment in patients with atrial fibrillation
Introduction Anticoagulation therapy is pivotal in the management of stroke prevention in atrial fibrillation (AF). Prospective registries, containing longitudinal data are lacking with detailed information on anticoagulant therapy, treatment adherence and AF-related adverse events in practice-based patient cohorts, in particular for non-vitamin K oral anticoagulants (NOAC). With the creation of DUTCH-AF, a nationwide longitudinal AF registry, we aim to provide clinical data and answer questions on the (anticoagulant) management over time and of the clinical course of patients with newly diagnosed AF in routine clinical care. Within DUTCH-AF, our current aim is to assess the effect of non-adherence and non-persistence of anticoagulation therapy on clinical adverse events (eg, bleeding and stroke), to determine predictors for such inadequate anticoagulant treatment, and to validate and refine bleeding prediction models. With DUTCH-AF, we provide the basis for a continuing nationwide AF registry, which will facilitate subsequent research, including future registry-based clinical trials. Methods and analysis The DUTCH-AF registry is a nationwide, prospective registry of patients with newly diagnosed 'non-valvular' AF. Patients will be enrolled from primary, secondary and tertiary care practices across the Netherlands. A target of 6000 patients for this initial cohort will be followed for at least 2 years. Data on thromboembolic and bleeding events, changes in antithrombotic therapy and hospital admissions will be registered. Pharmacy-dispensing data will be obtained to calculate parameters of adherence and persistence to anticoagulant treatment, which will be linked to AF-related outcomes such as ischaemic stroke and major bleeding. In a subset of patients, anticoagulation adherence and beliefs about drugs will be assessed by questionnaire. Ethics and dissemination This study protocol was approved as exempt for formal review according to Dutch law by the Medical Ethics Committee of the Leiden University Medical Centre, Leiden, the Netherlands. Results will be disseminated by publications in peer-reviewed journals and presentations at scientific congresses
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
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