Search results for " Integration"
showing 10 items of 1034 documents
Devenir chercheur ou enseignant chercheur : le goût pour la recherche des doctorants à l'épreuve du marché du travail
2016
Faire une thèse pour devenir chercheur ou enseignant-chercheur est souvent considéré comme un parcours difficile dont le résultat est incertain. Plus que dans d’autres pays, les diplômés de doctorat en France connaissent de fortes difficultés de stabilisation sur le marché du travail. Notre recherche s’interroge sur les raisons qui conduisent les jeunes à obtenir un doctorat puis à choisir une carrière de chercheur ou d’enseignant-chercheur et enfin, à s’y stabiliser. À partir d’une enquête du Céreq, nos résultats montrent que l’intérêt pour la recherche qu’ils ont manifesté dès le début des études supérieures et le capital social vont fortement structurer leur parcours universitaire et pro…
An integrated approach based on uniform quantization for the evaluation of complexity of short-term heart period variability: Application to 24 h Hol…
2007
We propose an integrated approach based on uniform quantization over a small number of levels for the evaluation and characterization of complexity of a process. This approach integrates information-domain analysis based on entropy rate, local nonlinear prediction, and pattern classification based on symbolic analysis. Normalized and non-normalized indexes quantifying complexity over short data sequences (â¼300 samples) are derived. This approach provides a rule for deciding the optimal length of the patterns that may be worth considering and some suggestions about possible strategies to group patterns into a smaller number of families. The approach is applied to 24 h Holter recordings of …
A Lagrangian method for deriving new indefinite integrals of special functions
2015
A new method is presented for obtaining indefinite integrals of common special functions. The approach is based on a Lagrangian formulation of the general homogeneous linear ordinary differential equation of second order. A general integral is derived which involves an arbitrary function, and therefore yields an infinite number of indefinite integrals for any special function which obeys such a differential equation. Techniques are presented to obtain the more interesting integrals generated by such an approach, and many integrals, both previously known and completely new are derived using the method. Sample results are given for Bessel functions, Airy functions, Legendre functions and hype…
Analytic structure ofϕ4theory using light-by-light sum rules
2013
Abstract We apply a sum rule for the forward light-by-light scattering process within the context of the ϕ 4 quantum field theory. As a consequence of the sum rule a stringent causality criterion is presented and the resulting constraints are studied within a particular resummation of graphs. Such resummation is demonstrated to be consistent with the sum rule to all orders of perturbation theory. We furthermore show the appearance of particular non-perturbative solutions within such approximation to be a necessary requirement of the sum rule. For a range of values of the coupling constant, these solutions manifest themselves as a physical bound state and a K-matrix pole. For another domain …
Intrinsic Acidity of Surface Sites in Calcium Silicate Hydrates and Its Implication to Their Electrokinetic Properties
2014
Calcium Silicate Hydrates (C–S–H) are the major hydration products of portland cement paste. The accurate description of acid–base reactions at the surface of C–S–H particles is essential for both understanding the ion sorption equilibrium in cement and prediction of mechanical properties of the hardened cement paste. Ab initio molecular dynamics simulations at the density functional level of theory were applied to calculate intrinsic acidity constants (pKa’s) of the relevant ≡SiOH and ≡CaOH2 groups on the C–S–H surfaces using a thermodynamic integration technique. Ion sorption equilibrium in C–S–H was modeled applying ab initio calculated pKa’s in titrating Grand Canonical Monte Carlo simu…
High-order services and spatial change in the central and eastern European countries
2004
This paper examines the level of high-order services in the CEECs. These services are of growing strategic importance across the whole range of production sectors in developed economies (Bailly and Coffey, 1994). They are both the cause and the consequence of globalization, in a cumulative process. It is through high-order services that large cities, and the regions around them, become closely interconnected within global networks. These services are fundamental features both in the changing pattern of regional disparities across an enlarged EU and in the process of metropolization (Bourdeau-Lepage, 2004a and Bourdeau-Lepage Huriot, 2002 and 2004). The development of high-order services wil…
Social isolation from communities and child maltreatment: a cross-cultural comparison.
2003
Objective: The aim of this study is to determine: (1) the differences between Spanish and Colombian cultures in relation to community social support variables, and (2) the relationships between community social support variables and child maltreatment in both cultures. Method: The study was based on 670 nonabusive families and 166 abusive families. The parents were asked to complete the Community Social Support Questionnaire. This instrument measures community social support in terms of Community Integration and Satisfaction, membership in voluntary organizations and community participation, and use of Community Resources of Social Support. Results: Differences between both cultures were fo…
Implementation of local chiral interactions in the hyperspherical harmonics formalism
2021
With the goal of using chiral interactions at various orders to explore properties of the few-body nuclear systems, we write the recently developed local chiral interactions as spherical irreducible tensors and implement them in the hyperspherical harmonics expansion method. We devote particular attention to three-body forces at next-to-next-to leading order, which play an important role in reproducing experimental data. We check our implementation by benchmarking the ground-state properties of $^3$H, $^3$He and $^4$He against the available Monte Carlo calculations. We then confirm their order-by-order truncation error estimates and further investigate uncertainties in the charge radii obta…
Characterization of chromatographic peaks using the linearly modified Gaussian model. Comparison with the bi-Gaussian and the Foley and Dorsey approa…
2017
To characterize column performance in liquid chromatography, several parameters must be obtained from experimental data. These parameters can be computed through the numerical integration of the net signal to calculate the moments after subtraction of the baseline. This requires the establishment of the peak integration limits. The whole process introduces significant uncertainty. For this reason, several alternative procedures have been proposed to measure the area, mean time and variance, based on the assumption that the chromatographic peak can be described with a mathematical function. This allows the calculation of the peak position and variance making use of the values of the experime…
Limits of multi-linear gradient optimisation in reversed-phase liquid chromatography
2005
Abstract The concept of limiting peak purity was applied to quantify the degree of completion of the separation capability of a chromatographic system using multi-linear gradients. The objective was to check whether the complexity of a gradient program deserves be increased to enhance resolution by inserting more linear segments, or on the contrary, no significant improvements can be expected under more complex gradients. A set of 19 isoindole derivatives of primary amino acids was selected to test the performance of isocratic, single linear and multi-linear gradients. Accurate simulated chromatograms were obtained via numerical integration of the general equation of gradient elution, using…