Search results for "RAV"

An algorithm for the Rural Postman problem on a directed graph

1986

The Directed Rural Postman Problem (DRPP) is a general case of the Chinese Postman Problem where a subset of the set of arcs of a given directed graph is ‘required’ to be traversed at minimum cost. If this subset does not form a weakly connected graph but forms a number of disconnected components the problem is NP-Complete, and is also a generalization of the asymmetric Travelling Salesman Problem. In this paper we present a branch and bound algorithm for the exact solution of the DRPP based on bounds computed from Lagrangean Relaxation (with shortest spanning arborescence sub-problems) and on the fathoming of some of the tree nodes by the solution of minimum cost flow problems. Computation…

SELF-ENERGIES AND VERTEX CORRECTIONS WITH TWO FACTORIZING LOOPS

1999

A complete set of factorizing two-loop self-energies and vertex corrections is calculated analytically for arbitrary masses and momenta — including the case of collinear singularities — within the ℛ-functions approach.

Does the GATT/WTO promote trade? After all, Rose was right

2019

This paper re-examines the effect of the GATT/WTO on trade using recent econometric developments that allow us estimating structural gravity equations with the Poisson pseudo-maximum likelihood (PPML) estimator on a large dataset that requires computing high-dimensional fixed effects. By doing so, we overcome computational limitations that are present in previous studies. In line with Rose’s (Am Econ Rev 94:98–114, 2004) seminal work, we find that, unlike regional trade agreements and currency unions, the GATT/WTO accession has not generated positive trade effects. This result is robust to the use of alternative measures of trade flows, across periods and country groups, to changes in the p…

About Compactness of Faddeev Integral Equations for Three Charged Particles

1999

Momentum space three-body integral equations of the Faddeev type can not be used for Coulomb-like potentials, for energies above the breakup threshold. The reason is the occurrence of singularities in their kernels which destroy the compactness properties known to exist for purely short-range interactions. Using the rigorously equivalent formulation in terms of an effective-two- body theory, we prove that the nondiagonal kernels occurring therein possess on and off the energy shell only integrable singularities, provided all three particles have charges of the same sign (ie., only repulsive Coulomb interactions). In contrast, if some of the charges have opposite signs the nondiagonal kernel…

Division sexuelle du travail, qualification et gestion de la main d’œuvre : une comparaison France-Brésil

1985

Travail des élèves et performance scolaire

2010

National audience; Le rendement scolaire du travail scolaire, exprimé par le rapport entre le score à une évaluation internationale et le temps de travail total des élèves, varie beaucoup d'un pays à l'autre. les pays où les élèves déclarent travailler le plus, qui sont aussi les pays où la religiosité est la plus forte, sont ceux où les scores sont les plus faibles. Une part de ce constat, qu'il est impossible de déterminer précisément, peut cependant s'expliquer par un biais dans les déclarations des élèves. Entre élèves au sein des pays, le temps de travail varie plus ou moins selon le pays, et de façon plus ou moins liée au score des élèves d'une part, à leur héritage social d'autre par…

Les méandres du travail au féminin: une comparaison dans 14 pays de la Méditerranée

2010

Cette communication s'appuie sur une comparaison du travail féminin dans quatorze pays du pourtour méditerranéen hors Union européenne. Au-delà de la proximité géographique, certains éléments rendent ces territoires semblables et comparables entre eux, d'autres les différencient nettement. La région méditerranée est marquée par le risque élevé du chômage des jeunes et la fragilité de la participation économique des femmes. La lente avancée féminine a un prix, une résonance particulière dans les pays Arabes : chômage, sous-emploi, concentration dans un petit nombre de métiers et de secteurs d'activité, accès limité aux professions de haut niveau, salaire faible... Pourtant certains pays leur…

Price dispersion, competition, and the role of online travel agents: Evidence from business routes in the Italian airline market

2014

Abstract In this article, using data from the Italian airline market, we study the role of online travel agents (OTAs) in driving price dispersion as compared to the effect of airlines’ websites. Specifically, we investigate how distinctive factors between OTAs and airlines’ direct channels influence price dispersion. We find that after controlling for OTAs’ features related to airline competition, price dispersion should be lower in the OTA channel relative to airlines’ direct channels. On the other hand, we also find that OTAs’ features related to the presence of airline competition play in favor of higher price dispersion in such indirect channel.

Personality and music preferences: the influence of personality traits on preferences regarding musical elements.

2005

The purpose of this scientific study was to determine how personality traits, as classified by Cattell, influence preferences regarding musical elements. The subject group consisted of 145 students, male and female, chosen at random from different Polish universities. For the purpose of determining their personality traits the participants completed the 16PF Questionnaire (Cattell, Saunders, & Stice, 1957; Russel & Karol, 1993), in its Polish adaptation by Choynowski (Nowakowska, 1970). The participants' musical preferences were determined by their completing a Questionnaire of Musical Preferences (specifically created for the purposes of this research), in which respondents indicated their…

Singularity formation for Prandtl’s equations

2009

Abstract We consider Prandtl’s equations for an impulsively started disk and follow the process of the formation of the singularity in the complex plane using the singularity tracking method. We classify Van Dommelen and Shen’s singularity as a cubic root singularity. We introduce a class of initial data, uniformly bounded in H 1 , which have a dipole singularity in the complex plane. These data lead to a solution blow-up whose time can be made arbitrarily short within the class. This is numerical evidence of the ill-posedness of the Prandtl equations in H 1 . The presence of a small viscosity in the streamwise direction changes the behavior of the singularities. They stabilize at a distanc…