Search for neutrino radiative decays during a total solar eclipse

We present the results of the measurements performed in the occasion of the 2001 total solar eclipse, looking for visible photons emitted through a possible radiative decay of solar neutrinos. We establish lower limits for the \nu_2 and \nu_3 proper lifetimes above 10^3 s/eV, for neutrino masses larger than 10^{-2} eV.Comment: 11 pages, 7 figures, presented at AHEP2003, Valenci

Monte Carlo simulation of an experiment looking for radiative solar neutrino decays

We analyse the possibility of detecting visible photons from a hypothetical radiative decay of solar neutrinos. Our study is focused on the simulation of such measurements during total solar eclipses and it is based on the BP2000 Standard Solar Model and on the most recent experimental information concerning the neutrino properties.Comment: 13 pages, 10 figures, accepted by Astropart. Phy

Search for possible neutrino radiative decays during the 2001 total solar eclipse

We present the results of the observations performed in the occasion of the June 21, 2001 total solar eclipse, looking for visible photons emitted trough a possible radiative decay of solar neutrinos. We establish lower limits for the neutrino proper lifetimes larger than 1000 s/eV, for neutrino masses larger than 0.01 eV.Comment: 18 pages, 11 figures, accepted by Astopart. Phys, updated reference

An Experimental Investigation of Violations of Transitivity in Choice under Uncertainty

Several models of choice under uncertainty imply systematic violations of transitivity of preference. Our experiments explored whether people show patterns of intransitivity predicted by these models. To distinguish “true” violations from those produced by “error,” a model was fit in which each choice can have a different error rate and each person can have a different pattern of true preferences that does not need to be transitive. Error rate for a choice is estimated from preference reversals between repeated presentations of the same choice. Our results showed that very few people repeated intransitive patterns. We can retain the hypothesis that transitivity best describes the data of the vast majority of participants.decision making, errors, regret theory, transitivity

Information theory: coding theorems for discrete memoryless systems

Information Theor

Décadas de Michels: marcos contextuais e prazo de validade para a "lei de ferro"

O argumento central deste artigo é que existe um prazo de validade temporal para o efeito da lei de ferro das oligarquias, proposição cunhada por Robert Michels em sua obra Sociologia dos partidos políticos, de 1911. O artigo esboça, na primeira seção, as bases sociais e institucionais que serviram como marcos contextuais propícios à conversão dos partidos socialistas europeus em princípios do século XX em oligarquias partidárias: a expansão do sufrágio e a integração na competição eleitoral de candidatos desprovidos de propriedades e renda, combinado a reformas eleitorais, com a substituição do voto majoritário pela representação proporcional, especialmente acompanhada pela transferência aos dirigentes da prerrogativa de confecção e classificação de listas de candidatos partidários. Na segunda seção, o artigo procura matizar os prognósticos sombrios de Robert Michels acerca da organização partidária, considerando os fatores que contribuem para maior ou menor delegação do poder interno dos partidos aos seus dirigentes