Search results for "Inverse"
showing 10 items of 630 documents
Inverse estimation of terminal connections in the cardiac conduction system
2017
Modeling the cardiac conduction system is a challenging problem in the context of computational cardiac electrophysiology. Its ventricular section, the Purkinje system, is responsible for triggering tissue electrical activation at discrete terminal locations, which subsequently spreads throughout the ventricles. In this paper, we present an algorithm that is capable of estimating the location of the Purkinje system triggering points from a set of random measurements on tissue. We present the properties and the performance of the algorithm under controlled synthetic scenarios. Results show that the method is capable of locating most of the triggering points in scenarios with a fair ratio bet…
Space of signatures as inverse limits of Carnot groups
2021
We formalize the notion of limit of an inverse system of metric spaces with 1-Lipschitz projections having unbounded fibers. The construction is applied to the sequence of free Carnot groups of fixed rank n and increasing step. In this case, the limit space is in correspondence with the space of signatures of rectifiable paths in ℝn, as introduced by Chen. Hambly-Lyons’s result on the uniqueness of signature implies that this space is a geodesic metric tree. As a particular consequence we deduce that every path in ℝn can be approximated by projections of some geodesics in some Carnot group of rank n, giving an evidence that the complexity of sub-Riemannian geodesics increases with the step.…
A systematic review of inverse agonism at adrenoceptor subtypes
2020
As many, if not most, ligands at G protein-coupled receptor antagonists are inverse agonists, we systematically reviewed inverse agonism at the nine adrenoceptor subtypes. Except for β3-adrenoceptors, inverse agonism has been reported for each of the adrenoceptor subtypes, most often for β2-adrenoceptors, including endogenously expressed receptors in human tissues. As with other receptors, the detection and degree of inverse agonism depend on the cells and tissues under investigation, i.e., they are greatest when the model has a high intrinsic tone/constitutive activity for the response being studied. Accordingly, they may differ between parts of a tissue, for instance, atria vs. ventricles…
What are the effects of the aging of the neuromuscular system on postural stability?
2015
International audience; Aging is frequently associated with a decreased postural stability, essentially after 60 years, leading to an increased risk of falling. In this article we propose to highlight the influence of the aging of the neuromuscular system on postural stability when standing upright. To maintain balance while standing upright, human needs to control the activity of ankle muscles and particularly the plantar flexors. During the aging process, the performance of these muscles are strongly altered. It is commonly observed large deficits in elderly people with history of falls. Some authors reported an inverse correlation between the amplitude of postural sway and the capacity o…
Probability of hysterectomy in Germany
2018
Introduction Hysterectomy is the most common gynecological surgery in many industrialized countries. In Germany, the hysterectomy rate is high in comparison to other European countries. The aim of this analysis was to determine the distribution of age at hysterectomy as well as the age-specific probability of undergoing a hysterectomy between the ages of 0–64 in the German female population. Methods Analyses were based on data from the MARZY study, a prospective, randomized, population-based cohort study investigating early detection of cervical cancer in western Germany. At baseline, 6429 women were invited to attend cervical cancer screening. The distribution of age at hysterectomy as wel…
Inverse simulated annealing for the determination of amorphous structures
2013
We present a new and efficient optimization method to determine the structure of disordered systems in agreement with available experimental data. Our approach permits the application of accurate electronic structure calculations within the structure optimization. The new technique is demonstrated within density functional theory by the calculation of a model of amorphous carbon.
Femtosecond polarization spectroscopy in molecular gas mixtures: Macroscopic interference and concentration measurements
2000
0021-9606; Raman-induced polarization spectroscopy (RIPS) experiments combined with homodyne detection have been conducted with a femtosecond laser at room temperature and low pressure (p < 2 atm) in CO2-N2 mixtures as well as in air (O2-N2 mixtures). Each molecule of the mixture produces its own time-dependent signal, measured as a series of recurring transients. Macroscopic interference is observed when transients of both molecules overlap in the time domain. This interference leads to a large modification of the signal, which is well reproduced by calculations. The total signal recorded in CO2-N2 or O2-N2 mixtures of known concentration is analyzed in order to measure the polarizability …
Some Relationships between Molecular Energy-Topology and Symmetry
2001
Molecular Topology (M.T.) has demonstrated its efficiency in the prediction of many experimental parameters. The application of the topological indices to the prediction of pharmacological properties, and, above all, to its inverse problem, the drug design, is particularly interesting [1,2]. Several attempts to explain the reasons of such efficiency have been carried out [3,4]. So far, we are not close to a definitive answer.
Time-of-flight photoemission electron microscopy – a new way to chemical surface analysis
2001
Abstract The time structure of synchrotron radiation at BESSY I (Berlin) was utilised to operate a photoemission electron microscope in the time-of-flight mode. The electrons that are emitted from the sample surface with different energies are dispersed in a drift tube subsequent to the imaging optics. Two ways of fast image detection have been explored, a fast gated intensified CCD camera (800 ps gate time) and a special counting electronics in combination with a 3D (x,y,t)-resolving delay line detector ( time resolution ps). The latter device has a lateral resolution of about 50 μm in the image plane being equivalent to 1000 pixels along the image diagonal. An energy resolution of 400 meV…
Forward doubly-virtual Compton scattering off the nucleon in chiral perturbation theory: The subtraction function and moments of unpolarized structur…
2020
The forward doubly-virtual Compton scattering (VVCS) off the nucleon contains a wealth of information on nucleon structure, relevant to the calculation of the two-photon-exchange effects in atomic spectroscopy and electron scattering. We report on a complete next-to-leading-order (NLO) calculation of low-energy VVCS in chiral perturbation theory ($\chi$PT). Here we focus on the unpolarized VVCS amplitudes $T_1(\nu, Q^2)$ and $T_2(\nu, Q^2)$, and the corresponding structure functions $F_1(x, Q^2)$ and $F_2(x,Q^2)$. Our results are confronted, where possible, with "data-driven" dispersive evaluations of low-energy structure quantities, such as nucleon polarizabilities. We find significant dis…