paper we present UBVRI light curves obtained by the WEBT from 1994 to 2002, including the last, extended BL Lac 2001 campaign. A total of about 7500 optical observations performed by 31 telescopes from Japan to Mexico have been collected, to be added to the ∼15 600 observations of the BL Lac Campaign 2000. All these data allow one to follow the source optical emission behaviour with unprecedented detail. The analysis of the colour indices reveals that the flux variability can be interpreted in terms of two components: longer-term variations occurring on a fewday time scale appear as mildly-chromatic events, while a strong bluer-when-brighter chromatism characterizes very fast (intraday) flares. By decoupling the two components, we quantify the degree of chromatism inferring that longer-term flux changes imply moving along a ∼0.1 bluerwhen-brighter slope in the B − R versus R plane; a steeper slope of ∼0.4 would distinguish the shorter-term variations. This means that, when considering the long-term trend, the B-band flux level is related to the R-band one according to a power law of index ∼1.1. Doppler factor variations on a "convex" spectrum could be the mechanism accounting for both the long-term variations and their slight chromatism.

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: Relaxations in poly(etherimide) PEI Ultem 1000 have been analysed by di †erential scanning calorimetry (DSC), dynamic mechanical spectroscopy (DMS), dielectric relaxation spectroscopy (DRS) and thermally stimulated depolarization current (TSDC) measurements. DMTA and DRS results show three distinct relaxations c, b and a in the temperature range [140 to 250¡C. The Ðrst one depends strongly on the water content in the sample as will be discussed in more detail in the second paper of this series. These results are in good agreement with those observed by TSDC of conventionally polarized electrets. In addition to these three relaxations, TSDC measurements show : (1) a peak (o) at which is attributed to space charge temperatures above the a relaxation, (2) indications of structure in the b relaxation zone. In the case of electrets formed by the windowing polarization method, the resulting TSDC spectra allow us to discern the Ðne structure of the b relaxation, which is formed by three subrelaxations. In this work, the activation energies calculated by the di †erent techniques are compared, and a molecular origin for each relaxation is proposed.1998 SCI. Polym. Int. 46, 11È19 (1998)

Dielectric measurements (Thermally Stimulated Depolarization Currents and Broadband Dielectric Spectroscopy) have been performed near the glass transition to study the glass transition on the odd nonsymmetric liquid crystal dimers of the series α-(4-cyanobiphenyl-4´-oxy)-ω-(1-pyreniminebenzylidene-4´-oxy) alkanes (CBOnO.Py) with n ranging from 3 to 9. A previous study

We investigated the protective effect of Trypanosoma rangeli against infection with Trypanosoma cruzi in animal models of various ages and with different doses of inoculum. The age of the mice and the dose of parasites determined the course of the infection. When T. cruzi was inoculated into mice after challenge with T. rangeli, parasitaemia was more controlled, mortality decreased and histopathology showed lower inflammatory infiltration and pseudocysts. This study proposes a new murine model of the protective effect of recombinant proteins of T. rangeli for possible application in the vaccines field.

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Abstract. -We present results from a two year intensive monitoring of BL Lac object 3C 66A (PKS 0219+428).This object was observed in outburst during these two years. It reached the brightest ever observed magnitude on V=13.59 (1.2.1995) and on K=10.59 (15.2.1994). The optical and infrared light curves are characterised by randomly distributed fast flares, lasting a few days and well defined outbursts lasting a week or two. On top of these flares we can occasionally see small amplitude microvariability. No clear correlation can be found between the spectral behaviour and the occurrence of these flares. In the radio bands 3C 66A was quite faint and very stable compared to the optical variations. The light curves will be presented with preliminary analysis and discussions on the possible causes for the observed variations.

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