Search results for "IAC"
showing 10 items of 4189 documents
Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei
2008
Data collected by the Pierre Auger Observatory provide evidence for anisotropy in the arrival directions of the cosmic rays with the ighest-energies, which are correlated with the positions of relatively nearby active galactic nuclei (AGN) [Pierre Auger Collaboration, Science 318 (2007) 938]. The correlation has maximum significance for cosmic rays with energy greater than ~6 x 1019 eV and AGN at a distance less than ~75 Mpc. We have confirmed the anisotropy at a confidence level of more than 99% through a test with parameters specified a priori, using an independent data set. The observed correlation is compatible with the hypothesis that cosmic rays with the highest-energies originate fro…
Upper limit on the diffuse flux of ultrahigh energy tau neutrinos from the Pierre Auger Observatory
2008
The surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau neutrinos that interact in Earth’s crust. Tau leptons from ντ charged-current interactions can emerge and decay in the atmosphere to produce a nearly horizontal shower with a significant electromagnetic component. The data collected between 1 January 2004 and 31 August 2007 are used to place an upper limit on the diffuse flux of ντ at EeV energies. Assuming an E−2ν differential energy spectrum the limit set at 90% C.L. is E2νdNντdEν<1.3×10−7 GeV cm−2 s−1 sr−1 in the energy range 2×1017 eV<E<2×1019 eV.
Large-scale distribution of arrival directions of cosmic rays detected above 1018 eV at the Pierre Auger Observatory
2012
A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 1018 eV at the Pierre Auger Observatory is presented. This search is performed as a function of both declination and right ascension in several energy ranges above 1018 eV, and reported in terms of dipolar and quadrupolar coefficients. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole moments in this energy range, upper limits on their amplitudes are derived. These upper limits allow us to test the origin of cosmic rays above 1018 eV from stationary Galactic …
Phytochemistry of Weigela x "kosteriana variegata" (Caprifoliaceae)
2018
International audience; One new triterpene glycoside 3-O-beta-D-xylopyranosyl-(1 -> 4)-[beta-D-glucopyranosyl-(1 -> 3)]-beta-D-xyl opyranosyl-(1 -> 4)-beta-D-xylopyranosyl-(1 -> 3)-alpha-L-rhamnopyranosyl-(1 -> 2)-alpha-L-arabinopyranosyloleanolic acid, was isolated from Weigela x "kosteriana variegata" (Caprifoliaceae), with three known ones. Their structures were characterized by a combination of mass spectrometry and 1D and 2D NMR spectrocopic techniques including H-1- and C-13 NMR, COSY, TOCSY, NOESY, HSQC, and HMBC experiments. The toxicological properties of some glycosides were determined with a zebrafish-based assay. The results show that the most active compounds were toxic to the …
Inactivation of PadR, the repressor of the phenolic acid stress response, by molecular interaction with Usp1, a universal stress protein from Lactoba…
2009
ABSTRACT The phenolic acid decarboxylase gene padA is involved in the phenolic acid stress response (PASR) in gram-positive bacteria. In Lactobacillus plantarum , the padR gene encodes the negative transcriptional regulator of padA and is cotranscribed with a downstream gene, usp1 , which encodes a putative universal stress protein (USP), Usp1, of unknown function. The usp1 gene is overexpressed during the PASR. However, the role and the mechanism of action of the USPs are unknown in gram-positive bacteria. Therefore, to gain insights into the role of USPs in the PASR; (i) a usp1 deletion mutant was constructed; (ii) the two genes padR and usp1 were coexpressed with padA under its own promo…
Left-Ventricle Segmentation of SPECT Images of Rats
2015
Single-photon emission computed tomography (SPECT) imaging of the heart is helpful to quantify the left-ventricular ejection fraction and study myocardial perfusion scans. However, these evaluations require a 3-D segmentation of the left-ventricular wall on each phase of the cardiac cycle. This paper presents a fast and interactive graph cut method for 3-D segmentation of the left ventricle (LV) of rats in SPECT images. The method is carried out in three steps. First, 3-D sampling of the LV cavity is made in a spherical-cylindrical coordinate system. Then, a graph-cut-based energy minimization procedure provides delineation of the myocardium centerline surface. From there, it is possible to…
Study of mechanisms of action of an immunotherapy by triacyl lipid A in humans
2013
Immunotherapy acting at the primary tumor site and preventing the development of metastases is one of the strategies for treatment of patients with cancer. To improve the efficiency of the latter, it is necessary to understand how it induces tumor cell death. In the laboratory, it was observed the cure of PROb tumors in rats BDIX by the triacyl lipid A. It has been shown that this effect involved the immune system involving interactions with TLRs present in many tumor cells and innate immunity cells such as neutrophils.In this work, we investigated the possible involvement of neutrophils in the antitumor activity of triacyl lipid A in humans.In a Phase 1 study in patients with refractory so…
Walk tests : a standardizable tool to assess capacities in cardio-vascular disease
2011
Cardiovascular and cerebrovascular diseases remain the first cause of mortality and handicap in the world. With the improvements in the management of the acute phase, the number of patients with limited exercise capacity due to chronic cardiovascular disease is increasing. The aim of this thesis was to conduct a thorough study of the use of standardized walk tests to assess exercise capacity in coronary artery disease patients. We first explain the concepts of handicap and quality of life in chronic diseases, and the need for functional evaluations in order to assess their impact and evolution. We then present the current modalities of cardiac rehabilitation, emphasizing the importance of p…
Isolation and caracterisation of saponins from three plants of Araliaceae and Dracaenaceae families and evaluation of their cytotoxic activities on t…
2010
The interest of the substances from natural origin, potentially antitumor led us to interest in triterpenoid and steroidal saponins of plants from the African biodiversity belonging to the Araliaceae and Dracaenaceae families of plants. Indeed, of the former studies undertaken on some plants of these two families led to obtaining complex and original molecules having excellent cytotoxic, immuno-modulating, anti-inflammatory properties. Within sight of these results we undertook pharmaco-chemical investigations on Cussonia arborea (Araliaceae), Dracaena deisteliana, and Dracaena arborea (Dracaenaceae), medicinal plants usually used in african traditional pharmacopeia to treat various disease…
Effect of oxidoreduction potential on aroma biosynthesis by lactic acid bacteria in nonfat yogurt
2011
; The aim of this study was to investigate the effect of oxidoreduction potential (Eh) on the biosynthesis of aroma compounds by lactic acid bacteria in non-fat yogurt. The study was done with yogurts fermented by Lactobacillus bulgaricus and Streptococcus thermophilus. The Eh was modified by the application of different gaseous conditions (air, nitrogen, and nitrogen/hydrogen). Acetaldehyde, dimethyl sulfide, diacetyl, and pentane-2,3-dione, as the major endogenous odorant compounds of yogurt, were chosen as tracers for the biosynthesis of aroma compounds by lactic acid bacteria. Oxidative conditions favored the production of acetaldehyde, dimethyl sulfide, and diketones (diacetyl and pen…