993 resultados para Alain Badiou


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info:eu-repo/semantics/published

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info:eu-repo/semantics/published

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info:eu-repo/semantics/published

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info:eu-repo/semantics/published

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The hydrologic structure of Taal Volcano has favored development of an extensive hydrothermal system whose prominent feature is the acidic Main Crater Lake (pH<3) lying in the center of an active vent complex, which is surrounded by a slightly alkaline caldera lake (Lake Taal). This peculiar situation makes Taal prone to frequent, and sometimes catastrophic, hydrovolcanic eruptions. Fumaroles, hot springs, and lake waters were sampled in 1991, 1992, and 1995 in order to develop a geochemical model for the hydrothermal system. The low-temperature fumarole compositions indicate strong interaction of magmatic vapors with the hydrothermal system under relatively oxidizing conditions. The thermal waters consist of highly, moderately, and weakly mineralized solutions, but none of them corresponds to either water-rock equilibrium or rock dissolution. The concentrated discharges have high Na contents (>3500 mg/kg) and low SO4/Cl ratios (<0.3). The Br/Cl ratio of most samples suggests incorporation of seawater into the hydrothermal system. Water and dissolved sulfate isotopic compositions reveal that the Main Crater Lake and spring discharges are derived from a deep parent fluid (T≃300°C), which is a mixture of seawater, volcanic water, and Lake Taal water. The volcanic end member is probably produced in the magmatic-hydrothermal environment during absorption of high-temperature gases into groundwater. Boiling and mixing of the parent water give rise to the range of chemical and isotopic characteristics observed in the thermal discharges. Incursion of seawater from the coastal region to the central part of the volcano is supported by the low water levels of the lakes and by the fact that Lake Taal was directly connected to the China sea until the sixteenth century. The depth to the seawater-meteoric water interface is calculated to be 80 and 160 m for the Main Crater Lake and Lake Taal, respectively. Additional data are required to infer the hydrologic structure of Taal. Geochemical surveillance of the Main Crater Lake using the SO4/Cl, Na/K, or Mg/Cl ratio cannot be applied straightforwardly due to the presence of seawater in the hydrothermal system.

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The present randomized, placebo-controlled double-blind multicenter study included a population of 36 subjects with frequent recurrences (at least once a month) of herpes labialis. Most of the patients had failed to respond adequately to previous treatment with other therapeutic tools, including acyclovir. Either 50 mg of thymopentin or of placebo was administered 3 times a week, by the subcutaneous route, for 6 weeks. Subsequently, the patients were observed for nearly 6 months on the average. The results achieved with thymopentin for the individual parameters were significantly superior to those obtained with placebo; thus significant improvement was seen in patients on thymopentin in the duration of the longest symptomfree period (prolonged from 2.1 weeks to 20.9 weeks, p = 0.000), in the number of relapses (reduced from 1.6 to 0.4 episodes/month, p = 0.001), and in the total duration of herpes symptoms per month (shortened from 2.0 to 0.3 weeks, p = 0.000). Placebo treatment also resulted in considerable improvement (p < 0.05 or 0.01), but was significantly inferior to the improvement obtained with thymopentin. The longest symptomfree period in the placebo group was prolonged from 2.4 to 11.2 weeks. The number of relapses per month was reduced from 1.4 to 0.8, and the total duration of herpes symptoms per month from 2 to 0.9 weeks. The results of intergroup analyses, in which the observed parameters and the improvement achieved in either group were compared, significantly favored thymopentin treatment. The effect of thymopentin was in all but one parameters superior to that of placebo and highly significant (p < 0.01). © 1985 Humana Press Inc.

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In contrast to adults, Helicobacter pylori gastritis in children is reported as milder and ulcer disease as uncommon, but unequivocal data are lacking.

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We attempt to construct a unified evolutionary scheme that includes post-AGB systems, barium stars, symbiotics and related systems, explaining their similarities as well as their differences. Special attention is given to the comparison of the barium pollution and symbiotic phenomena. Finally, we outline a 'transient torus' evolutionary scenario that makes use of the various observational and theoretical hints and aims at explaining the observed characteristics of the relevant systems.

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BACKGROUND: In most emergency departments, tetanus prophylaxis currently relies on vaccination history. Bedside evaluation of tetanus immunity may improve this process. OBJECTIVES: (i) To determine the seroprevalence of tetanus immunity; (ii) to evaluate the accuracy of vaccination history in assessing tetanus immunity; (iii) to identify factors predictive of seroprotection and incorrect history. METHOD: In a prospective observational study, tetanus immunity was assessed in 784 adults using Tétanos Quick Stick (TQS). A questionnaire was completed to obtain vaccination and general histories. Immunity assessed by TQS and by vaccination history were compared with anti-tetanus antibody levels measured by the enzyme-linked immunosorbent assay (seroprotection threshold >0.15 IU/ml). RESULTS: Overall, 64.2% of patients were protected according to TQS results. Four independent predictors of seroprotection were identified: young age, birthplace in Belgium, male sex and occupational medicine consultation. TQS performance was good: kappa=0.71, sensitivity 85.3%, specificity 87.2%, positive predictive value 92.1% and negative predictive value 77.2%. Seven hundred and sixty-two participants responded to the vaccination history: 23.4% said they were protected, 22.1% that they were not and 54.5% did not know. History performance was poor: kappa=0.27, sensitivity 60.3%, specificity 73.3%, positive predictive value 81.8% and negative predictive value 45.8%. Compared with history, TQS offered a significantly better sensitivity, negative and positive predictive values, but specificity was similar. No predictor of an incorrect history was identified. CONCLUSION: Lack of protective immunity against tetanus is frequent but poorly evaluated by history taking. Several demographic characteristics are good predictors of seroprotection. TQS could be a valuable tool in selected patients to improve tetanus prophylaxis in the emergency department.

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Context. This paper is the last in a series devoted to the analysis of the binary content of the Hipparcos Catalogue. Aims. The comparison of the proper motions constructed from positions spanning a short (Hipparcos) or long time (Tycho-2) makes it possible to uncover binaries with periods of the order of or somewhat larger than the short time span (in this case, the 3 yr duration of the Hipparcos mission), since the unrecognised orbital motion will then add to the proper motion. Methods. A list of candidate proper motion binaries is constructed from a carefully designed χ2 test evaluating the statistical significance of the difference between the Tycho-2 and Hipparcos proper motions for 103 134 stars in common between the two catalogues (excluding components of visual systems). Since similar lists of proper-motion binaries have already been constructed, the present paper focuses on the evaluation of the detection efficiency of proper-motion binaries, using different kinds of control data (mostly radial velocities). The detection rate for entries from the Ninth Catalogue of Spectroscopic Binary Orbits (SB9) is evaluated, as well as for stars like barium stars, which are known to be all binaries, and finally for spectroscopic binaries identified from radial velocity data in the Geneva-Copenhagen survey of F and G dwarfs in the solar neighbourhood. Results. Proper motion binaries are efficiently detected for systems with parallaxes in excess of ∼20 mas, and periods in the range 1000-30 000 d. The shortest periods in this range (1000-2000 d, i.e. once to twice the duration of the Hipparcos mission) may appear only as DMSA/G binaries (accelerated proper motion in the Hipparcos Double and Multiple System Annex). Proper motion binaries detected among SB9 systems having periods shorter than about 400 d hint at triple systems, the proper-motion binary involving a component with a longer orbital period. A list of 19 candidate triple systems is provided. Binaries suspected of having low-mass (brown-dwarf-like) companions are listed as well. Among the 37 barium stars with parallaxes larger than 5 mas, only 7 exhibit no evidence for duplicity whatsoever (be it spectroscopic or astrometric). Finally, the fraction of proper-motion binaries shows no significant variation among the various (regular) spectral classes, when due account is taken for the detection biases. © ESO 2007.

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Anions such as Cl(-) and HCO3 (-) are well known to play an important role in glucose-stimulated insulin secretion (GSIS). In this study, we demonstrate that glucose-induced Cl(-) efflux from β-cells is mediated by the Ca(2+)-activated Cl(-) channel anoctamin 1 (Ano1). Ano1 expression in rat β-cells is demonstrated by reverse transcriptase-polymerase chain reaction, western blotting, and immunohistochemistry. Typical Ano1 currents are observed in whole-cell and inside-out patches in the presence of intracellular Ca(++): at 1 μM, the Cl(-) current is outwardly rectifying, and at 2 μM, it becomes almost linear. The relative permeabilities of monovalent anions are NO3 (-) (1.83 ± 0.10) > Br(-) (1.42 ± 0.07) > Cl(-) (1.0). A linear single-channel current-voltage relationship shows a conductance of 8.37 pS. These currents are nearly abolished by blocking Ano1 antibodies or by the inhibitors 2-(5-ethyl-4-hydroxy-6-methylpyrimidin-2-ylthio)-N-(4-(4-methoxyphenyl)thiazol-2-yl)acetamide (T-AO1) and tannic acid (TA). These inhibitors induce a strong decrease of 16.7-mM glucose-stimulated action potential rate (at least 87 % on dispersed cells) and a partial membrane repolarization with T-AO1. They abolish or strongly inhibit the GSIS increment at 8.3 mM and at 16.7 mM glucose. Blocking Ano1 antibodies also abolish the 16.7-mM GSIS increment. Combined treatment with bumetanide and acetazolamide in low Cl(-) and HCO3 (-) media provokes a 65 % reduction in action potential (AP) amplitude and a 15-mV AP peak repolarization. Although the mechanism triggering Ano1 opening remains to be established, the present data demonstrate that Ano1 is required to sustain glucose-stimulated membrane potential oscillations and insulin secretion.

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The Hyades stream has long been thought to be a dispersed vestige of the Hyades cluster. However, recent analyses of the parallax distribution, of the mass function, and of the action-space distribution of stream stars have shown it to be rather composed of orbits trapped at a resonance of a density disturbance. This resonant scenario should leave a clearly different signature in the element abundances of stream stars than the dispersed cluster scenario, since the Hyades cluster is chemically homogeneous. Here, we study the metallicity as well as the element abundances of Li, Na, Mg, Fe, Zr, Ba, La, Ce, Nd and Eu for a random sample of stars belonging to the Hyades stream, and compare them with those of stars from the Hyades cluster. From this analysis: (i) we independently confirm that the Hyades stream cannot be solely composed of stars originating in the Hyades cluster; (ii) we show thatsomestars (namely 2/21) from the Hyades stream nevertheless have abundances compatible with an origin in the cluster; (iii) we emphasize that the use of Li as a chemical tag of the cluster origin of main-sequence stars is very efficient in the range 5500K ≤Teff≤ 6200K, since the Li sequence in the Hyades cluster is very tight, while at the same time spanning a large abundance range; (iv) we show that, while this evaporated population has a metallicity excess of ~0.2 dex with respect to the local thin-disc population, identical to that of the Hyades cluster, the remainder of the Hyades stream population has still a metallicity excess of ~0.06-0.15 dex, consistent with an origin in the inner Galaxy and (v) we show that the Hyades stream can be interpreted as an inner 4:1 resonance of the spiral pattern: this then also reproduces an orbital family compatible with the Sirius stream, and places the origin of the Hyades stream up to 1kpc inwards from the solar radius, which might explain the observed metallicity excess of the stream population. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

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Catalogue de l'exposition d'esquisses et de photographies créée au Cercle des Voyageurs à Bruxelles du 9 novembre au 1er décembre 2007.