Search results for "function"
showing 10 items of 14432 documents
Bethe-Salpeter Approach for Meson-Meson Scattering in Chiral Perturbation Theory
1998
The Bethe-Salpeter equation restores exact elastic unitarity in the s- channel by summing up an infinite set of chiral loops. We use this equation to show how a chiral expansion can be undertaken by successive approximations to the potential which should be iterated. Renormalizability of the amplitudes in a broad sense can be achieved by allowing for an infinite set of counter-terms as it is the case in ordinary Chiral Perturbation Theory. Within this framework we calculate the $\pi \pi$ scattering amplitudes both for s- and p-waves at lowest order in the proposed expansion where a successful description of the low-lying resonances ($\sigma$ and $\rho$) and threshold parameters is obtained.…
CAT score single item analysis in patients with COPD: results from COSYCONET
2019
Abstract The COPD Assessment Test (CAT) is in widespread use for the evaluation of patients with chronic obstructive pulmonary disease (COPD). We assessed whether the CAT items carry additional information beyond the sum score regarding COPD characteristics including emphysema. Patients of GOLD grades 1 to 4 from the COPD cohort COSYCONET (German COPD and Systemic Consequences - Comorbidities Network) with complete CAT data were included (n = 2270), of whom 493 had chest CT evaluated for the presence of emphysema. Comorbidities and lung function were assessed following standardised procedures. Cross-sectional data analysis was based on multiple regression analysis of the single CAT items ag…
Associations of black carbon with lung function and airway inflammation in schoolchildren
2019
Background: Few studies have investigated the 24-hour respiratory health effects of personal black carbon (BC) and ultrafine particles (UFP) exposure in schoolchildren. The objective of this study was to investigate these associations with the lung function in children 10-years old with and without persistent respiratory symptoms. Methods: We conducted a cross-sectional study in 305 children (147 and 158 with and without persistent respiratory symptoms, respectively) from three European birth-cohorts: PARIS (France) and INMA Sabadell and Valencia (Spain). Personal 24-hour measurements of exposure concentrations to BC and UFP were performed by portable devices, before lung function testing. …
Nondeterministic operations on finite relational structures
1998
Abstract This article builds on a tutorial introduction to universal algebra for language theory (Courcelle, Theoret. Comput. Sci. 163 (1996) 1–54) and extends it in two directions. First, nondeterministic operations are considered, i.e., operations which give a set of results instead of a single one. Most of their properties concerning recognizability and equational definability carry over from the ordinary case with minor modifications. Second, inductive sets of evaluations are studied in greater detail. It seems that they are handled most naturally in the framework presented here. We consider the analogues of top-down and bottom-up tree transducers. Again, most of their closure propertie…
Experimental Evidence for an Attractive p-φ Interaction
2021
Physical review letters 127(17), 172301 (2021). doi:10.1103/PhysRevLett.127.172301
Theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis-, and trans-1,2-difluoroethylenes.
2014
A theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis- and trans-1,2-difluoroethylenes is reported. The results obtained using density functional theory (DFT) combined with large basis sets and gauge-independent atomic orbital calculations were critically compared with experiment and conventional, higher level correlated electronic structure methods. Accurate structural, vibrational, and NMR parameters of difluoroethylenes were obtained using several density functionals combined with dedicated basis sets. B3LYP/6-311++G(3df,2pd) optimized structures of difluoroethylenes closely reproduced experimental geometries and earlier reported b…
Universal infinitesimal Hilbertianity of sub-Riemannian manifolds
2019
We prove that sub-Riemannian manifolds are infinitesimally Hilbertian (i.e., the associated Sobolev space is Hilbert) when equipped with an arbitrary Radon measure. The result follows from an embedding of metric derivations into the space of square-integrable sections of the horizontal bundle, which we obtain on all weighted sub-Finsler manifolds. As an intermediate tool, of independent interest, we show that any sub-Finsler distance can be monotonically approximated from below by Finsler ones. All the results are obtained in the general setting of possibly rank-varying structures.
Rates of convergence to equilibrium for collisionless kinetic equations in slab geometry
2017
This work deals with free transport equations with partly diffuse stochastic boundary operators in slab geometry. Such equations are governed by stochastic semigroups in $L^{1}$ spaces$.\ $We prove convergence to equilibrium at the rate $O\left( t^{-\frac{k}{2(k+1)+1}}\right) \ (t\rightarrow +\infty )$ for $L^{1}$ initial data $g$ in a suitable subspace of the domain of the generator $T$ where $k\in \mathbb{N}$ depends on the properties of the boundary operators near the tangential velocities to the slab. This result is derived from a quantified version of Ingham's tauberian theorem by showing that $F_{g}(s):=\lim_{\varepsilon \rightarrow 0_{+}}\left( is+\varepsilon -T\right) ^{-1}g$ exists…
On the biomechanical function of scaffolds for engineering load-bearing soft tissues
2009
Replacement or regeneration of load-bearing soft tissues has long been the impetus for the development of bioactive materials. While maturing, current efforts continue to be confounded by our lack of understanding of the intricate multi-scale hierarchical arrangements and interactions typically found in native tissues. The current state of the art in biomaterial processing enables a degree of controllable microstructure that can be used for the development of model systems to deduce fundamental biological implications of matrix morphologies on cell function. Furthermore, the development of computational frameworks which allow for the simulation of experimentally derived observations represe…
Serum uric acid is not independently associated with plasma renin activity and plasma aldosterone in hypertensive adults
2017
Background and Aims In experimental investigations conducted in rats, raising serum uric acid (SUA) levels resulted in the stimulation of intrarenal renin expression. Studies in humans exploring the association of SUA with plasma renin activity (PRA) yielded conflicting results. Moreover, little is known about the relationship of SUA with plasma aldosterone concentration (PAC). The study aimed to assess the relationship between SUA levels, PRA, and PAC and the influence of age, gender, body mass index (BMI), and hyperuricemia on these relationships in subjects with essential hypertension (EH). Methods and Results We enrolled 372 hypertensive patients (mean age 45 ± 12 years, men 67%) with u…