The WEBT BL Lacertae Campaign 2001 and its extension : Optical light curves and colour analysis 1994–2002

BL Lacertae has been the target of four observing campaigns by the Whole Earth Blazar Telescope (WEBT) collaboration. In this paper we present UBVRI light curves obtained by theWEBT 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.Reig Torres, Pablo, [email protected]

The changing plant and tiller populations of timothy and meadow fescue swards. I. Plant survival and the pattern of tillering

In recent years several studies have increased our understanding of the growth and development of perennial herbage grasses. In particular, the production, life-history and development of individual tillers of single plants of timothy (Phleum pratense) grown in pots have been described (Langer 1956, 1957). As these studies took no account of competition between plants in swards, the growth of pure swards of timothy and meadow fescue (Festuca pratensis) was analysed in the field, first under conditions of uninterrupted growth (Langer 1958) and then under several cutting regimes (Langer 1959; Lambert 1962). However, since these experiments involved destructive sampling of small random areas of sward, no information could be obtained on the effect of management on the life-history of tillers or on the effect of competition on plant numbers. To consolidate the knowledge gained from previous work and to elucidate the fate of the individual components of the sward, an experiment was designed in which the life-histories of all tillers which arose within small, permanent quadrats of pure timothy and meadow fescue swards were studied over a period of 3 years. In this way it was possible to study, qualitatively and quantitatively, the development of swards of these two species from the seedling stage, under two cutting treatments based on agricultural practice

Efeitos de rações com níveis crescentes de cana-de-açúcar em substituição à silagem de milho sobre a população de protozoários ciliados no rúmen de ovinos Effects of diets with increasing levels of sugar cane in substitution of corn silage on rumen population ciliate protozoa in sheep

Oito ovinos machos com fístulas ruminais foram delineados em dois quadrados latinos, em quatro períodos de 35 dias cada e quatro tratamentos, compreendendo níveis crescentes de cana-de-açúcar (CA) em substituição à silagem de milho (SM): A) 100% SM; B) 67% SM e 33% CA; C) 33% SM e 67% CA; e D 100% CA, para avaliação da população de protozoários ciliados no rúmen. As concentrações totais de protozoários ciliados no rúmen e de Entodinium diminuíram e os valores de pH do conteúdo ruminal aumentaram linearmente com o incremento das quantidades de cana-de-açúcar na ração. Não houve diferenças entre tratamentos para o volume ruminal e a taxa de passagem da fase líquida do rúmen.<br>Eight rumen fistulated rams were delineated in two Latin Squares in four periods of 35 days each and four treatments consisted of increasing levels of sugar cane (SC) in substitution to the corn silage (CS): A) 100% CS, B) 67% CS and 33% SC, C) 33% CS and 67% SC and D) 100% SC, to evaluate the population of ciliate protozoa in the rumen. The total concentrations of rumen ciliate protozoa and of Entodinium decreased and the values of pH of the ruminal content increased linearly as dietary sugar cane levels increased. No differences between treatments were observed for the rumen volume and the rumen liquid turnover rate