700 research outputs found
Net Charge on a Noble Gas Atom Adsorbed on a Metallic Surface
Adsorbed noble gas atoms donate (on the average) a fraction of an electronic
charge to the substrate metal. The effect has been experimentally observed as
an adsorptive change in the electronic work function. The connection between
the effective net atomic charge and the binding energy of the atom to the metal
is theoretically explored.Comment: ReVvTeX 3.1 format, Two Figures, Three Table
Non-Equilibrium Electron Transport in Two-Dimensional Nano-Structures Modeled by Green's Functions and the Finite-Element Method
We use the effective-mass approximation and the density-functional theory
with the local-density approximation for modeling two-dimensional
nano-structures connected phase-coherently to two infinite leads. Using the
non-equilibrium Green's function method the electron density and the current
are calculated under a bias voltage. The problem of solving for the Green's
functions numerically is formulated using the finite-element method (FEM). The
Green's functions have non-reflecting open boundary conditions to take care of
the infinite size of the system. We show how these boundary conditions are
formulated in the FEM. The scheme is tested by calculating transmission
probabilities for simple model potentials. The potential of the scheme is
demonstrated by determining non-linear current-voltage behaviors of resonant
tunneling structures.Comment: 13 pages,15 figure
Clinical implications of low estimated protein intake in patients with heart failure
Background: A higher protein intake has been associated with a higher muscle mass and lower mortality rates in the general population, but data about protein intake and survival in patients with heart failure (HF) are lacking.
Methods: We studied the prevalence, predictors, and clinical outcome of estimated protein intake in 2516 patients from the BIOlogy Study to TAilored Treatment in Chronic Heart Failure (BIOSTAT-CHF) index cohort. Protein intake was calculated in spot urine samples using a validated formula [13.9 + 0.907 * body mass index (BMI) (kg/m2) + 0.0305 * urinary urea nitrogen level (mg/dL)]. Association with mortality was assessed using multivariable Cox regression models. All findings were validated in an independent cohort.
Results: We included 2282 HF patients (mean age 68 ± 12 years and 27% female). Lower estimated protein intake in HF patients was associated with a lower BMI, but with more signs of congestion. Mortality rate in the lowest quartile was 32%, compared with 18% in the highest quartile (P < 0.001). In a multivariable model, lower estimated protein intake was associated with a higher risk of death compared with the highest quartile [hazard ratio (HR) 1.50; 95% confidence interval (CI) 1.03â2.18, P = 0.036 for the lowest quartile and HR 1.46; 95% CI 1.00â2.18, P = 0.049 for the second quartile].
Conclusions: An estimated lower protein intake was associated with a lower BMI, but signs of congestion were more prevalent. A lower estimated protein intake was independently associated with a higher mortality risk.publishedVersio
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Time-Dependent Models for a decade of SN 1993J
A classical and a relativistic law of motion for a supernova remnant (SNR)
are deduced assuming an inverse power law behavior for the density of the
interstellar medium and applying the thin layer approximation. A third equation
of motion is found in the framework of relativistic hydrodynamics with
pressure, applying momentum conservation. These new formulas are calibrated
against a decade of observations of \snr. The existing knowledge of the
diffusive processes of ultrarelativistic electrons is reviewed in order to
explain the behavior of the `U' shaped profile of intensity versus distance
from the center of SN 1993J.Comment: 20 pages 19 figures, Accepted for pubblication in Astrophysics and
Space Science 201
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in âs = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fbâ1 of protonâproton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
Portal Vein Embolization is Associated with Reduced Liver Failure and Mortality in High-Risk Resections for Perihilar Cholangiocarcinoma
Background: Preoperative portal vein embolization (PVE) is frequently used to improve future liver remnant volume (FLRV) and to reduce the risk of liver failure after major liver resection. Objective: This paper aimed to assess postoperative outcomes after PVE and resection for suspected perihilar cholangiocarcinoma (PHC) in an international, multicentric cohort. Methods: Patients undergoing resection for suspected PHC across 20 centers worldwide, from the year 2000, were included. Liver failure, biliary leakage, and hemorrhage were classified according to the respective International Study Group of Liver Surgery criteria. Using propensity scoring, two equal cohorts were generated using matching parameters, i.e. age, sex, American Society of Anesthesiologists classification, jaundice, type of biliary drainage, baseline FLRV, resection type, and portal vein resection. Results: A total of 1667 patients were treated for suspected PHC during the study period. In 298 patients who underwent preoperative PVE, the overall incidence of liver failure and 90-day mortality was 27% and 18%, respectively, as opposed to 14% and 12%, respectively, in patients without PVE (p < 0.001 and p = 0.005). After propensity score matching, 98 patients were enrolled in each cohort, resulting in similar baseline and operative characteristics. Liver failure was lower in the PVE group (8% vs. 36%, p < 0.001), as was biliary leakage (10% vs. 35%, p < 0.01), intra-abdominal abscesses (19% vs. 34%, p = 0.01), and 90-day mortality (7% vs. 18%, p = 0.03). Conclusion: PVE before major liver resection for PHC is associated with a lower incidence of liver failure, biliary leakage, abscess formation, and mortality. These results demonstrate the importance of PVE as an integral component in the surgical treatment of PHC
The energy spectrum of cosmic rays beyond the turn-down around 10^17 eV as measured with the surface detector of the Pierre Auger Observatory
We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the spectrum is observed, confirming the presence of the so-called second-knee feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays
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