Claudio Silva

Statistical modelling and prediction of atmospheric pollution by particulate material: two nonparametric approaches

Atmospheric particles are one of the main factors of air pollution in Santiago, Chile. Inhalation of particulate material is known to lead to serious health problems, including respiratory illness and complications related thereto. Vehicular traffic, industrial activity and street dust are important sources of atmospheric particles. The public authorities in Santiago have been monitoring air pollution by means of a network of semi-automatic sampling stations. At one of these stations, located near the city centre close to Government House, both PM2.5 and PM10 particulate material concentrations have been measured continuously for several years. Here PM2.5 refers to particles having a diameter smaller than 2.5 microns and PM10 corresponds to particles smaller than 10 microns. Hourly averages of the concentrations are available. For the present work, hourly data recorded at intervals of 12 hours have been used. The aim is to describe and forecast these variables with satisfactory precision, including critical pollution episodes, both as a function of previous behaviour and of a set of meteorological variables, comprising wind speed and direction, ambient temperature and relative air humidity. Both non-parametric discriminant analysis and multivariate adaptive regression splines procedures have been applied. Highly satisfactory classification as well as forecasting results were achieved with these approaches, respectively. Copyright

Air pollution impact on phagocytic capacity of peripheral blood macrophages and antioxidant activity of plasma among school children

Peripheral blood macrophages of school children from downtown Santiago, Chile--a highly polluted city--exhibited a lower phagocytic index with higher percentage of killing than those of the rural village of María Pinto. These findings were observed concomitantly with a lower antioxidant activity of plasma in Santiago students. No differences were observed in serum immunoglobulins (IgA, IgG, and IgM), secretory IgA in saliva, and complement component C3. White blood cell count was higher in María Pinto residents than in Santiago students, including those cells with phagocytic capacity. It is suggested that particulate air pollution may enhance macrophage activity with impairment of the antioxidant capacity of plasma.

Evaluation of weighted rankings using expected significance level

The use of weighted rankings to analyze complete blocks designs (Quade, 1979) is a practical way of recovering between-block information. A family of old and new test statistics can be generated by this procedure. Selection among these statistics and comparison with parametric and nonparametric competitors are based on expected significance level [ESL] in small designs (3 to 6 blocks, 3 to 5 treatments).

Estimating the asymptotic relative efficiency of weighted rankings

Five tests for the hypothesis of no treatment effects in complete blocks designs are compared with respect to asymptotic relative efficiency: the ordinary two-way analysis of variance, the analysis of variance of ranks (Friedman, 1937), the method of ranking after alignment (Hodges and Lehmann, 1962), and a method of weighted rankings proposed by Quade (1972, 1979). This comparison required devising a procedure for estimating the asymptotic relative efficiencies of test statistics with asymp-totic chi-squared distributions.

Antifascist Front and military politics of the Communist Party of Chile under dictatorship, 1973-1980

This article inquires about the route of the military politics of the Communist Party of Chile, particularly under its political commitment to the Antifascist Front (1973-1980). In this regard, we argue that, in a first stage, this party pursued its military politics primarily based on evaluations about the causes of Allende’s defeat. This implied an almost unrestricted continuity of its military politics during the early years of dictatorship. However, after the first measures taken in order to palliate its shortcomings, and also face the imminent extension and institutionalization of dictatorship, there was a slow, but significant expansion of its military politics in the late 1970s, a dynamics that ended up contributing both to the political reconfiguration of its militancy and its commitment to bring the dictatorship to an end.

El Frente Antifascista y la Política Militar del Partido Comunista de Chile bajo dictadura, 1973-1980

Este articulo indaga la trayectoria de la politica militar del Partido Comunista de Chile, particularmente bajo su apuesta politica de Frente Antifascista (1973-1980). Al respecto, sostenemos que, en una primera etapa, este partido desarrollo su politica militar fundamentalmente en base a las evaluaciones realizadas sobre las causas de la derrota de Allende. Lo anterior implico una continuidad casi irrestricta de su politica militar durante los primeros anos de dictadura. No obstante, a partir de las primeras medidas tomadas en funcion de palear las deficiencias de esta, asi como tambien frente el inminente alargue e institucionalizacion de la dictadura, se produjo una lenta pero significativa ampliacion de su politica militar a fines de los 1970, dinamica que termino contribuyendo tanto a la reconfiguracion politica de su militancia como a su apuesta para terminar con la dictadura.