Merger between Zon Multimedia and Sonaecom: revisiting the consolidation scenario

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economic

Statistics, distillation, and ordering emergence in a two-dimensional stochastic model of particles in counterflowing streams

In this paper, we proposed a stochastic model which describes two species of particles moving in counterflow. The model generalizes the theoretical framework describing the transport in random systems since particles can work as mobile obstacles, whereas particles of one species move in opposite direction to the particles of the other species, or they can work as fixed obstacles remaining in their places during the time evolution. We conducted a detailed study about the statistics concerning the crossing time of particles, as well as the effects of the lateral transitions on the time required to the system reaches a state of complete geographic separation of species. The spatial effects of jamming were also studied by looking into the deformation of the concentration of particles in the two-dimensional corridor. Finally, we observed in our study the formation of patterns of lanes which reach the steady state regardless the initial conditions used for the evolution. A similar result is also observed in real experiments involving charged colloids motion and simulations of pedestrian dynamics based on Langevin equations, when periodic boundary conditions are considered (particles counterflow in a ring symmetry). The results obtained through Monte Carlo numerical simulations and numerical integrations are in good agreement with each other. However, differently from previous studies, the dynamics considered in this work is not Newton-based, and therefore, even artificial situations of self-propelled objects should be studied in this first-principle modeling.Comment: 27 pages, 13 figure

ECommerce in retail: europe snapshot and future challenges

CEM

Introdução de Harmonia axyridis PALLAS (Col., Coccinellidae) na Ilha de Santa Maria.

V Expedição Científica do Departamento de Biologia – Santa Maria e Formigas 1990.A modificação das práticas culturais e o emprego indiscriminado de pesticidas levaram ao desaparecimento de numerosos predadores afidífagos nos Açores e consequentemente ao aparecimento de desiquilíbrios ecológicos (praga/predador). A fim de atenuar esta situação, desde há 3 anos (1988/1990), que vimos introduzindo na Ilha de Santa Maria (Açores) uma joaninha exótica de origem asiática Harmonia axyridis PALLAS. A escolha deste predador deve-se à sua grande capacidade de adaptação às condições abióticas dos Açores, à sua grande plasticidade alimentar, às suas enormes capacidades predadoras e ao seu alto poder reprodutor (IABLOKOFF-KHNZORIAN, 1982; SCHANDERL, 1987). Durante estes 3 anos verificamos a sua capacidade de dispersão (adultos) e o seu poder predador (larvas do 3º estado) em relação às espécies de afídios existentes em pomares de citrinos