Parties and Ballot Access in Latin America: a new trend in a new political context

For the last ten years a group of Latin American countries have passed legal reforms raising ballot access requirements. Although each of these reforms have been profusely discussed in every one of the countries involved, so far, they have not been linked as constituting a regional trend. Firstly this paper shows that this trend actually exists, so reversing the dominant leaning on reforms in this field during the 1980s and 1990s. Secondly, the paper shows that the ongoing regional trend emerges in the aftermath of a legitimacy crisis which has been surmounted in every one of the cases. More specifically, the paper identifies a common sequence followed by four countries (Argentina, Colombia, Mexico and Peru) which leads to the raise of ballot access requirements. The sequence involves the following stages: first, a legitimacy crisis which paves the way to reforms opening up the political system; second, once the legitimacy crisis is left behind, a consensus emerges on the negative consequences of the previous reforms; and third, this consensus culminates with the introduction of the restrictive reforms which have dominated the Latin American landscape for the last decade. Every case is analyzed by observing the coalescence of what Matthew Shugart (2001) defined as the inherent and contingent conditions necessary to account for the passing of electoral reforms.Fil: Scherlis Perel, Gerardo Ezequiel. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Magnetic field effect on tunnel ionization of deep impurities by terahertz radiation

A suppression of tunnelling ionization of deep impurities in terahertz frequency electric fields by a magnetic field is observed. It is shown that the ionization probability at external magnetic field, B, oriented perpendicular to the electric field of terahertz radiation, E, is substantially smaller than that at B || E. The effect occurs at low temperatures and high magnetic fields

Estimación del costo económico en Argentina de la mortalidad atribuible al tabaco en adultos.

Existe amplia evidencia científica que vincula al tabaquismo con la mortalidad. Para estimar el costo de la mortalidad anual atribuible al tabaco (MAT) para adultos en Argentina se utilizaron datos de prevalencia de consumo de fumadores y ex fumadores (SEDRONAR), riesgos relativos de muerte por las patologías relevantes (Cancer Prevention Study II), muertes por dichas enfermedades y el valor de la consecuente productividad perdida. Se concluye que en el 2000, se produjeron 39.131 MAT en Argentina en los mayores de 35 años (16% de las de ese grupo). El costo anual medido como pérdida de ingresos futuros por mortalidad prematura fue de 469 millones de pesos, implicando esto $14 por habitante y 0,17% del PBI del año 2000. También se encontraron diferencias debidas a cada causa de mortalidad por sexo y edad.Epidemiología, Tabaco, Mortalidad, Valuación

Transient quantum evolution of 2D electrons under photoexcitation of a deep center

We have considered the ballistic propagation of the 2D electron Wigner distribution, which is excited by an ultrashort optical pulse from a short-range impurity into the first quantized subband of a selectively-doped heterostructure with high mobility. Transient ionization of a deep local state into a continuum conduction c-band state is described. Since the quantum nature of the photoexcitation, the Wigner distribution over 2D plane appears to be an alternating-sign function. Due to a negative contribution to the Wigner function, the mean values (concentration, energy, and flow) demonstrate an oscillating transient evolution in contrast to the diffusive classical regime of propagation.Comment: 8 pages, 6 figures, pape