280 research outputs found

    Blood-feeding in the young adult filarial worms litomosoides sigmodontis

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    In this study with the filarial model Litomosoides sigmodontis, we demonstrate that the worms ingest host red blood cells at a precise moment of their life-cycle, immediately after the fourth moult. The red blood cells (RBC) were identified microscopically in live worms immobilized in PBS at 4 degrees C, and their density assessed. Two hosts were used: Mongolian gerbils, where microfilaraemia is high, and susceptible BALB/c mice with lower microfilaraemia. Gerbils were studied at 12 time-points, between day 9 post-inoculation (the worms were young 4th stage larvae) and day 330 p.i. (worms were old adults). Only the very young adult filarial worms had red blood cells in their gut. Haematophagy was observed between days 25 and 56 p.i. and peaked between day 28 and day 30 p.i. in female worms. In males, haematophagy was less frequent and intense. Similar kinetics of haematophagy were found in BALB/c mice, but frequency and intensity tended to be lower. Haematophagy seems useful to optimize adult maturation. These observations suggest that haematophagy is an important step in the life-cycle of L. sigmodontis. This hitherto undescribed phenomenon might be characteristic of other filarial species including human parasites

    Robust and efficient estimation of the shape parameter of alpha-stable distributions

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    In this paper we consider robust and efficient estimators of the shape parameter of symmetric alpha-stable distributions obtained by using the Minimum Density Power Divergence method introduced in Basu, Harris, Hjort and Jones (1998). We established their high asymptotic efficiency and verified these results in simulations. The functionals corresponding to the estimators have bounded influence functions and simulations confirm their robustness when the sample distribution is in a vicinity of the model distribution. The simulations also show that the Minimum Density Power Divergence Estimators (MDPDEs) of the shape parameter of alpha-stable distributions have superior performance over other existing estimators. The high efficiency combined with robustness of the MDPDEs in estimating the shape parameter of alpha-stable distributions make them an attractive alternative to the preceding estimation procedures considered in the literature

    Modelling weather data by approximate regression quantiles.

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    In the paper we introduce and explore an approximate regression quantiles method. It is based on a new interpretation of M-functionals as quantiles of probability distributions which are determined by the original distribution and the M-function. A correction factor can be applied and this brings the corrected M-functional, called an approximate quantile functional, very close to the quantiles of the original distribution. In the present paper we extend approximate quantile functionals onto parametric models and call them approximate regression quantiles . We next model probability distributions of some weather components as they vary over time. We use very simple, but non-linear, parametric models. By applying the approximate regression quantiles method we obtain five-curve summaries of the varying over time probability distributions of the considered weather components

    Parties, promiscuity and politicisation: business-political networks in Poland

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    Research on post-communist political economy has begun to focus on the interface between business and politics. It is widely agreed that informal networks rather than business associations dominate this interface, but there has been very little systematic research in this area. The literature tends to assume that a politicised economy entails business-political networks that are structured by parties. Theoretically, this article distinguishes politicisation from party politicisation and argues that the two are unlikely to be found together in a post-communist context. Empirically, elite survey data and qualitative interviews are used to explore networks of businesspeople and politicians in Poland. Substantial evidence is found against the popular idea that Polish politicians have business clienteles clearly separated from each other according to party loyalties. Instead, it is argued that these politicians and businesspeople are promiscuous. Since there seems to be little that is unusual about the Polish case, this conclusion has theoretical, methodological, substantive and policy implications for other post-communist countries

    Intraoperative transfusion practices in Europe

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    Background: Transfusion of allogeneic blood influences outcome after surgery. Despite widespread availability of transfusion guidelines, transfusion practices might vary among physicians, departments, hospitals and countries. Our aim was to determine the amount of packed red blood cells (pRBC) and blood products transfused intraoperatively, and to describe factors determining transfusion throughout Europe. Methods: We did a prospective observational cohort study enrolling 5803 patients in 126 European centres that received at least one pRBC unit intraoperatively, during a continuous three month period in 2013. Results: The overall intraoperative transfusion rate was 1.8%; 59% of transfusions were at least partially initiated as a result of a physiological transfusion trigger-mostly because of hypotension (55.4%) and/or tachycardia (30.7%). Haemoglobin (Hb)-based transfusion trigger alone initiated only 8.5% of transfusions. The Hb concentration [mean (SD)] just before transfusion was 8.1 (1.7) g dl(-1) and increased to 9.8 (1.8) g dl(-1) after transfusion. The mean number of intraoperatively transfused pRBC units was 2.5 (2.7) units (median 2). Conclusions: Although European Society of Anaesthesiology transfusion guidelines are moderately implemented in Europe with respect to Hb threshold for transfusion (7-9 g dl(-1)), there is still an urgent need for further educational efforts that focus on the number of pRBC units to be transfused at this threshold
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