1,651 research outputs found
Subleading Shape Functions in Inclusive B Decays
The contributions of subleading shape functions to inclusive decay
distributions of B mesons are derived from a systematic two-step matching of
QCD current correlators onto soft-collinear and heavy-quark effective theory.
At tree-level, the results can be expressed in terms of forward matrix elements
of bi-local light-cone operators. Four-quark operators, which arise at O(g^2),
are included. Their effects can be absorbed entirely into a redefinition of
other shape functions. Our results are in disagreement with some previous
studies of subleading shape-function effects in the literature. A numerical
analysis of B->X_u+l+nu decay distributions suggests that power corrections are
small, with the possible exception of the endpoint region of the charged-lepton
energy spectrum.Comment: 22 pages, 2 figures; several typos corrected; version published in
JHE
Association between infectious burden, socioeconomic status, and ischemic stroke
Background and aims: Infectious diseases contribute to stroke risk, and are associated with socioeconomic status (SES). We tested the hypotheses that the aggregate burden of infections increases the risk of ischemic stroke (IS) and partly explains the association between low SES and ischemic stroke. Methods: In a case-control study with 470 ischemic stroke patients and 809 age- and sex-matched controls, randomly selected from the population, antibodies against the periodontal microbial agents Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, against Chlamydia pneumonia, Mycoplasma pneumoniae (IgA and IgG), and CagA-positive Helicobacter pylori (IgG) were assessed. Results: IgA seropositivity to two microbial agents was significantly associated with IS after adjustment for SES (OR 1.45 95% CI 1.01-2.08), but not in the fully adjusted model (OR 1.32 95% CI 0.86-2.02). By trend, cumulative IgA seropositivity was associated with stroke due to large vessel disease (LVD) after full adjustment (OR 1.88, 95% CI 0.96e3.69). Disadvantageous childhood SES was associated with higher cumulative seropositivity in univariable analyses, however, its strong impact on stroke risk was not influenced by seroepidemiological data in the multivariable model. The strong association between adulthood SES and stroke was rendered nonsignificant when factors of dental care were adjusted for. Conclusions: Infectious burden assessed with five microbial agents did not independently contribute to ischemic stroke consistently, but may contribute to stroke due to LVD. High infectious burden may not explain the association between childhood SES and stroke risk. Lifestyle factors that include dental negligence may contribute to the association between disadvantageous adulthood SES and stroke. (C) 2016 Elsevier Ireland Ltd. All rights reserved.Peer reviewe
There Goes the Neighborhood? – People‘s Attitudes and the Effects of Immigration to Australia
Dynamical mean-field theory for bosons
We discuss the recently developed bosonic dynamical mean-field (B-DMFT)
framework, which maps a bosonic lattice model onto the selfconsistent solution
of a bosonic impurity model with coupling to a reservoir of normal and
condensed bosons. The effective impurity action is derived in several ways: (i)
as an approximation to the kinetic energy functional of the lattice problem,
(ii) using a cavity approach, and (iii) by using an effective medium approach
based on adding a one-loop correction to the selfconsistently defined
condensate. To solve the impurity problem, we use a continuous-time Monte Carlo
algorithm based on a sampling of a perturbation expansion in the hybridization
functions and the condensate wave function. As applications of the formalism we
present finite temperature B-DMFT phase diagrams for the bosonic Hubbard model
on a 3d cubic and 2d square lattice, the condensate order parameter as a
function of chemical potential, critical exponents for the condensate, the
approach to the weakly interacting Bose gas regime for weak repulsions, and the
kinetic energy as a function of temperature.Comment: 26 pages, 19 figure
Electroweak Gauge-Boson Production at Small q_T: Infrared Safety from the Collinear Anomaly
Using methods from effective field theory, we develop a novel, systematic
framework for the calculation of the cross sections for electroweak gauge-boson
production at small and very small transverse momentum q_T, in which large
logarithms of the scale ratio M_V/q_T are resummed to all orders. These cross
sections receive logarithmically enhanced corrections from two sources: the
running of the hard matching coefficient and the collinear factorization
anomaly. The anomaly leads to the dynamical generation of a non-perturbative
scale q_* ~ M_V e^{-const/\alpha_s(M_V)}, which protects the processes from
receiving large long-distance hadronic contributions. Expanding the cross
sections in either \alpha_s or q_T generates strongly divergent series, which
must be resummed. As a by-product, we obtain an explicit non-perturbative
expression for the intercept of the cross sections at q_T=0, including the
normalization and first-order \alpha_s(q_*) correction. We perform a detailed
numerical comparison of our predictions with the available data on the
transverse-momentum distribution in Z-boson production at the Tevatron and LHC.Comment: 34 pages, 9 figure
Complete-Graph Tensor Network States: A New Fermionic Wave Function Ansatz for Molecules
We present a new class of tensor network states that are specifically
designed to capture the electron correlation of a molecule of arbitrary
structure. In this ansatz, the electronic wave function is represented by a
Complete-Graph Tensor Network (CGTN) ansatz which implements an efficient
reduction of the number of variational parameters by breaking down the
complexity of the high-dimensional coefficient tensor of a
full-configuration-interaction (FCI) wave function. We demonstrate that CGTN
states approximate ground states of molecules accurately by comparison of the
CGTN and FCI expansion coefficients. The CGTN parametrization is not biased
towards any reference configuration in contrast to many standard quantum
chemical methods. This feature allows one to obtain accurate relative energies
between CGTN states which is central to molecular physics and chemistry. We
discuss the implications for quantum chemistry and focus on the spin-state
problem. Our CGTN approach is applied to the energy splitting of states of
different spin for methylene and the strongly correlated ozone molecule at a
transition state structure. The parameters of the tensor network ansatz are
variationally optimized by means of a parallel-tempering Monte Carlo algorithm
Ab initio study of step formation and self-diffusion on Ag(100)
Using the plane wave pseudopotential method we performed density functional
theory calculations on the stability of steps and self-diffusion processes on
Ag(100). Our calculated step formation energies show that the {111}-faceted
step is more stable than the {110}-faceted step. In accordance with
experimental observations we find that the equilibrium island shape should be
octagonal very close to a square with predominately {111}-faceted steps. For
the (100) surface of fcc metals atomic migration proceeds by a hopping or an
exchange process. For Ag(100) we find that adatoms diffuse across flat surfaces
preferentially by hopping. Adatoms approaching the close-packed {111}-faceted
step edges descend from the upper terrace to the lower level by an atomic
exchange with an energy barrier almost identical to the diffusion barrier on
flat surface regions. Thus, within our numerical accuracy (approx +- 0.05 eV)
there is no additional step-edge barrier to descent. This provides a natural
explanation for the experimental observations of the smooth two-dimensional
growth in homoepitaxy of Ag(100). Inspection of experimental results of other
fcc crystal surfaces indicates that our result holds quite generally.Comment: 10 pages, 9 figures. Submitted to Phys. Rev B (October 31, 1996
EASIX for Prediction of Outcome in Hospitalized SARS-CoV-2 Infected Patients
BackgroundThe coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and has evoked a pandemic that challenges public health-care systems worldwide. Endothelial cell dysfunction plays a key role in pathophysiology, and simple prognosticators may help to optimize allocation of limited resources. Endothelial activation and stress index (EASIX) is a validated predictor of endothelial complications and outcome after allogeneic stem cell transplantation. Aim of this study was to test if EASIX could predict life-threatening complications in patients with COVID-19.MethodsSARS-CoV-2-positive, hospitalized patients were enrolled onto a prospective non-interventional register study (n=100). Biomarkers were assessed at hospital admission. Primary endpoint was severe course of disease (mechanical ventilation and/or death, V/D). Results were validated in 126 patients treated in two independent institutions.ResultsEASIX at admission was a strong predictor of severe course of the disease (odds ratio for a two-fold change 3.4, 95%CI 1.8-6.3, p<0.001), time to V/D (hazard ratio (HR) for a two-fold change 2.0, 95%CI 1.5-2.6, p<0.001) as well as survival (HR for a two-fold change 1.7, 95%CI 1.2-2.5, p=0.006). The effect was retained in multivariable analysis adjusting for age, gender, and comorbidities and could be validated in the independent cohort. At hospital admission EASIX correlated with increased suppressor of tumorigenicity-2, soluble thrombomodulin, angiopoietin-2, CXCL8, CXCL9 and interleukin-18, but not interferon-alpha.ConclusionEASIX is a validated predictor of COVID19 outcome and an easy-to-access tool to segregate patients in need for intensive surveillance
Very rare, exclusive, hadronic decays in QCD factorization
We study exclusive hadronic decays of the electroweak bosons Z, W and h in the framework of QCD factorization. We show that the theory uncertainties in these channels are remarkably small compared to past applications of the QCD factorization framework. While the branching ratios are small, many of the modes are accessible at future colliders. The Higgs decays exhibit interesting dependences on the couplings due to the interferences of different diagram topologies, making the h → Vγ decays possible probes of the quark Yukawa couplings and the h → VZ decays probes of the coupling between the Higgs boson, a photon and a Z-boson
Soft tissue damage after minimally invasive THA: A comparison of 5 approaches
Methods 5 surgeons each performed a total hip arthroplasty on 5 fresh frozen cadaver hips, using either a MIS anterior, MIS anterolateral, MIS 2-incision, MIS posterior, or lateral transgluteal approach. Postoperatively, the hips were dissected and muscle damage color-stained. We measured proportional muscle damage relative to the midsubstance cross-sectional surface area (MCSA) using computerized color detection. The integrity of external rotator muscles, nerves, and ligaments was assessed by direct observation. Results None of the other MIS approaches resulted in less gluteus medius muscle damage than the lateral transgluteal approach. However, the MIS anterior approach completely preserved the gluteus medius muscle in 4 cases while partial damage occurred in 1 case. Furthermore, the superior gluteal nerve was transected in 4 cases after a MIS anterolateral approach and in 1 after the lateral transgluteal approach. The lateral femoral cutaneous nerve was transected once after both the MIS anterior approach and the MIS 2-incision approach. Interpretation The MIS anterior approach may preserve the gluteus medius muscle during total hip arthroplasty, but with a risk of damaging the lateral femoral cutaneous nerv
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