Hopf bifurcation in higher dimensional differential systems via the averaging method

"vegeu el resum a l'inici del document del fitxer adjunt."

A Data mining approach to indirect inference

Consider a model with parameter phi, and an auxiliary model with parameter theta. Let phi be a randomly sampled from a given density over the known parameter space. Monte Carlo methods can be used to draw simulated data and compute the corresponding estimate of theta, say theta_tilde. A large set of tuples (phi, theta_tilde) can be generated in this manner. Nonparametric methods may be use to fit the function E(phi|theta_tilde=a), using these tuples. It is proposed to estimate phi using the fitted E(phi|theta_tilde=theta_hat), where theta_hat is the auxiliary estimate, using the real sample data. This is a consistent and asymptotically normally distributed estimator, under certain assumptions. Monte Carlo results for dynamic panel data and vector autoregressions show that this estimator can have very attractive small sample properties. Confidence intervals can be constructed using the quantiles of the phi for which theta_tilde is close to theta_hat. Such confidence intervals are found to have very accurate coverage.

Creació d'un sistema de gestió d'avaries en un sistema d'informació geogràfica de distribució d'aigües creat amb GEOMEDIA PUBLICWORKS

En aquesta memòria es realitza una introducció als SIG, Sistemes d'Informació Geogràfica, abastant els aspectes teòrics necessaris per poder implementar un SIG, Així com presentant els resultats obtinguts en una aplicació pràctica dels coneixements adquirits.

A theory of international conflict management and sanctioning

In this paper we analyze sanctioning policies in international law. We develop a model of international military conflict where the conflicting countries can be a target of international sanctions. These sanctions constitute an equilibrium outcome of an international political market for sanctions, where different countries trade political influence. We show that the level of sanctions in equilibrium is strictly positive but limited, in the sense that higher sanctions would exacerbate the military conflict, not reduce it. We then propose an alternative interpretation to the perceived lack of effectiveness of international sanctions, by showing that the problem might not be one of undersanctioning but of oversanctioning.

Dertosa: colonia de Pèrtinax?

En aquest treball, s¿hi replanteja l¿estatut de Tortosa a partir de la fi del segle II, tot considerant de nou CIL II2 14, 787 i CIL II2 14, 788. La possibilitat que l¿emperador efímer Pèrtinax concedís a Dertosa el privilegi colonial, com ho féu amb altres ciutats, és analitzada per tal de justificar el text de l¿última inscripció.

1.48 and 1.84 µm thulium emissions in monoclinic KGd(WO4)2 single crystals

By exciting at 788 nm, we have characterized the near infrared emissions of trivalent thulium ions in monoclinic KGd(WO4)2 single crystals at 1.48 and 1.84 mm as a function of dopant concentration from 0.1% to 10% and temperature from 10 K to room temperature. We used the reciprocity method to calculate the maximum emission cross-section of 3.0310220 cm2 at 1.838 mm for the polarization parallel to the Nm principal optical direction. These results agrees well with the experimental data. Experimental decay times of the 3H4!3F4 and 3F4!3H6 transitions have been measured as a function of thulium concentration.