Polytechnic University of Catalonia

About: Polytechnic University of Catalonia is a education organization based out in Barcelona, Spain. It is known for research contribution in the topics: Finite element method & Population. The organization has 16006 authors who have published 45325 publications receiving 949306 citations. The organization is also known as: UPC - BarcelonaTECH & Technical University of Catalonia.

Extinction and self-organized criticality in a model of large-scale evolution.

Abstract: A simple model of large-scale biological evolution is presented. This model involves an $N$-species system where interactions take place through a given connectivity matrix, which can change with time. True extinctions, with removal of less-fit species, occur followed by episodes of diversification. An order parameter may be naturally defined in the model. Through the dynamical equations, the system moves towards the critical threshold, which triggers the extinctions. The frequency distribution $N(s)$ of extinctions of size $s$ follows a power law $N(s)\ensuremath{\approx}{s}^{\ensuremath{-}\ensuremath{\alpha}}$ with $\ensuremath{\alpha}\ensuremath{\approx}2.3$, close to known palaeobiological evidence.

Quasihalo Orbits Associated with Libration Points

Abstract: Quasihalo orbits are Lissajous trajectories librating about the well known halo orbits. The main feature of these orbits is that they keep an exclusion zone in the same way that halo orbits do. As a result, the knowledge of this type of orbit gives more flexibility to the mission analysis design about collinear libration points of any pair of primaries in the solar system. This paper is devoted to the semianalytical computation of quasihalo orbits in the circular restricted three-body problem by means of an ad hoc Lindstedt-Poincare method. The study of the practical convergence of the procedure and the extension of the orbits to suitable locations in the solar system using Jet Propulsion Laboratory (JPL) ephemerides is also discussed.

Spatial Social Behavior in Second Life

Abstract: We have developed software bots that inhabit the popular online social environment SecondLife (SL). Our bots can wander around, collect data, engage in simple interactions, and carry out simple automated experiments. In this paper we use our bots to study spatial social behavior. We found an indication that SL users display distinct spatial behavior when interacting with other users. In addition, in an automated experiment carried out by our bot, we found that users, when their avatars were approached by our bot, tended to respond by moving their avatar, further indicating the significance of proxemics in SL.