Governo eletrônico na mídia on line: análise de repercussão das iniciativas de e-gov em publicações jornalísticas na web

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção.A presente pesquisa teve o objetivo geral de avaliar a repercussão nos meios de comunicação das ações governamentais relacionadas ao processo de implantação do governo eletrônico. Como objetivos específicos, buscou-se identificar as publicações com maior volume e freqüência sobre governo eletrônico, os assuntos e instâncias governamentais com maior destaque no noticiário e avaliar aspectos qualitativos da cobertura. Trata-se de um estudo descritivo, com a análise estatística sobre um conjunto de 475 notícias coletadas de diversas fontes jornalísticas on line entre junho de 2001 e novembro de 2002. Confirmando os pressupostos assumidos, o estudo demonstrou que: a veiculação de notícias sobre governo eletrônico é restrita, em razão de suas especificidades tecnológicas; as iniciativas de governo eletrônico do Poder Executivo federal são veiculadas com maior destaque; a cobertura tende a enfatizar aspectos relacionados à prestação de serviços, com menor destaque para questões relacionadas ao controle social do Estado. As conclusões do estudo indicam que o debate sobre o governo eletrônico ainda se restringe principalmente à esfera administrativa do Estado, enquanto que há carência de abordagem mais ampla do tema governo eletrônico nos órgãos da grande imprensa, a qual, por deter um público leitor mais numeroso, inclusive entre a parcela da sociedade onde se situam os formadores de opinião, poderia dar uma maior repercussão social ao tema

The electrical behaviour of rat connexin46 gap junction channels expressed in transfected HeLa cells

Pairs of human HeLa cells expressing rat connexin46 were used to study the electrical properties of gap junction channels with the dual voltage-clamp method. The steady-state conductance (g j,ss) had a bell-shaped dependence on transjunctional voltage (V j). The parameters of the Boltzmann fit were: V j,0=42mV, g j,min=0.12, z=2.5 (pipette solution: K+ aspartate−; 27°C). The Boltzmann parameters were sensitive to the ionic composition of the pipette solution (KCl, K+ aspartate−, TEA+ Cl−, TEA+ aspartate−). The Vj-dependent inactivation of the junctional current I j was approximated by single exponentials (exceptions: two exponentials with KCl at V j≥75mV and K+ aspartate− at V j=125mV). The time constant of inactivation (τi) decreased with increasing V j and was sensitive to the pipette solution. The larger the ions, the slower the inactivation. Recovery from inactivation followed a single exponential. The time constant of recovery (τr) increased with increasing V j. Single-channel currents showed a main state, several substates and a residual state. The corresponding conductances γj,main and γj,residual decreased slightly with increasing V j; extrapolation to V j=0mV yielded values of 152 and 28pS, respectively (K+ aspartate−; 37°C). The values of γj,main and γj,residual were dependent on pipette solution. The ratio γj,main/γj,residual increased with increasing ionic size, suggesting that the residual state impairs ion permeation more severely than the main state. The γj,main data suggest that the ionic selectivity of Cx46 channels may be controlled primarily by ionic size. Compared with hemichannel results, docking of connexons may modify the channel structure and thereby affect the ionic selectivity of gap junction channels. The open channel probability at steady state (P o) decreased with increasing V j. The parameters of the Boltzmann fit were: V j,0=41mV, z=2.2 (K+ aspartate−; 27°C

Subconductance States of Cx30 Gap Junction Channels: Data from Transfected HeLa Cells versus Data from a Mathematical Model

Human HeLa cells expressing mouse connexin30 were used to study the electrical properties of gap junction channel substates. Experiments were performed on cell pairs using a dual voltage-clamp method. Single-channel currents revealed discrete levels attributable to a main state, a residual state, and five substates interposed, suggesting the operation of six subgates provided by the six connexins of a gap junction hemichannel. Substate conductances, γ(j,substate), were unevenly distributed between the main-state and the residual-state conductance (γ(j,main state) = 141 pS, γ(j,residual state) = 21 pS). Activation of the first subgate reduced the channel conductance by ∼30%, and activation of subsequent subgates resulted in conductance decrements of 10–15% each. Current transitions between the states were fast (<2 ms). Substate events were usually demarcated by transitions from and back to the main state; transitions among substates were rare. Hence, subgates are recruited simultaneously rather than sequentially. The incidence of substate events was larger at larger gradients of V(j). Frequency and duration of substate events increased with increasing number of synchronously activated subgates. Our mathematical model, which describes the operation of gap junction channels, was expanded to include channel substates. Based on the established V(j)-sensitivity of γ(j,main state) and γ(j,residual state), the simulation yielded unique functions γ(j,substate) = f(V(j)) for each substate. Hence, the spacing of subconductance levels between the channel main state and residual state were uneven and characteristic for each V(j)