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Sökning: WFRF:(Favre P)

  • Resultat 11-20 av 22
  • Föregående 1[2]3Nästa
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  • Antonova, M., et al. (författare)
  • Proposal for characterization of muon spectrometers for neutrino beam lines with the Baby MIND
  • 2015
  • Rapport (övrigt vetenskapligt)abstract
    • Neutrino detectors based on state-of-the-art plastic scintillators read out with solid state photo-sensors, as well as new magnetization schemes, have been developed in the framework of AIDA. Meaningful size prototypes are under construction. In the framework of the CERN neutrino platform, we propose to test a Totally Active Scintillator Detector (TASD) and a prototype of a Magnetized Iron Neutrino Detector (MIND), called Baby MIND in the H8 beam line in 2016-2018. The design of the detectors and the purpose and plans for the beam tests are presented. An opportunity to use the Baby MIND detector in a real neutrino beam at JPARC for the measurement of the cross-section ratio between Water and scintillator (WAGASCI experiment) is described.
  • Blondel, A., et al. (författare)
  • The SuperFGD Prototype charged particle beam tests
  • 2020
  • Ingår i: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221 .- 1748-0221. ; 15:12
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel scintillator detector, the SuperFGD, has been selected as the main neutrino target for an upgrade of the T2K experiment ND280 near detector. The detector design will allow nearly 47r coverage for neutrino interactions at the near detector and will provide lower energy thresholds, significantly reducing systematic errors for the experiment. The SuperFGD is made of optically-isolated scintillator cubes of size 10 x 10 x 10 mm(3), providing the required spatial and energy resolution to reduce systematic uncertainties for future T2K runs. The SuperFGD for T2K will have close to two million cubes in a 1920 x 560 x 1840 mm(3) volume. A prototype made of 24 x 8 x 48 cubes was tested at a charged particle beamline at the CERN PS facility. The SuperFGD Prototype was instrumented with readout electronics similar to the future implementation for T2K. Results on electronics and detector response are reported in this paper, along with a discussion of the 3D reconstruction capabilities of this type of detector. Several physics analyses with the prototype data are also discussed, including a study of stopping protons.
  • Coutens, A., et al. (författare)
  • The ALMA-PILS survey: First detections of deuterated formamide and deuterated isocyanic acid in the interstellar medium
  • 2016
  • Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 590
  • Tidskriftsartikel (refereegranskat)abstract
    • Formamide (NH2CHO) has previously been detected in several star-forming regions and is thought to be a precursor for different prebiotic molecules. Its formation mechanism is still debated, however. Observations of formamide, related species, and their isopotologues may provide useful clues to the chemical pathways leading to their formation. The Protostellar Interferometric Line Survey (PILS) represents an unbiased, high angular resolution and sensitivity spectral survey of the low-mass protostellar binary IRAS 16293-2422 with the Atacama Large Millimeter/submillimeter Array (ALMA). For the first time, we detect the three singly deuterated forms of NH2CHO (NH2CDO, cis-and trans-NHDCHO), as well as DNCO towards the component B of this binary source. The images reveal that the different isotopologues are all present in the same region. Based on observations of the 13C isotopologues of formamide and a standard 12C/13C ratio, the deuterium fractionation is found to be similar for the three different forms with a value of about 2%. The DNCO/HNCO ratio is also comparable to the D/H ratio of formamide (~1%). These results are in agreement with the hypothesis that NH2CHO and HNCO are chemically related through grain-surface formation.
  • Favre, Cécile J., et al. (författare)
  • Organization of Ca2+ stores in myeloid cells: association of SERCA2b and the type-1 inositol-1,4,5-trisphosphate receptor
  • 1996
  • Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 316:1, s. 137-142
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we have analysed the relationship between Ca2+ pumps and Ins(1,4,5)P3-sensitive Ca2+ channels in myeloid cells. To study whether sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA)-type Ca2+-ATPases are responsible for Ca2+ uptake into Ins(1,4,5)P3-sensitive Ca2+ stores, we used the three structurally unrelated inhibitors thapsigargin, 2,5-di-t-butylhydroquinone and cyclopiazonic acid. In HL-60 cells, all three compounds precluded formation of the phosphorylated intermediate of SERCA-type Ca2+-ATPases. They also decreased, in parallel, ATP-dependent Ca2+ accumulation and the amount of Ins(1,4,5)P3-releasable Ca2+. Immunoblotting with subtype-directed antibodies demonstrated that HL-60 cells contain the Ca2+ pump SERCA2 (subtype b), and the Ca2+-release-channel type-1 Ins(1,4,5)P3 receptor. In subcellular fractionation studies, SERCA2 and type-1 Ins(1,4,5)P3 receptor co-purified. Immunofluorescence studies demonstrated that both type-1 Ins(1,4,5)P3 receptor and SERCA2 were evenly distributed throughout the cell in moving neutrophils. During phagocytosis both proteins translocated to the periphagosomal space. Taken together, our results suggest that in myeloid cells (i) SERCA-type Ca2+-ATPases function as Ca2+ pumps of Ins(1,4,5)P3-sensitive Ca2+ stores, and (ii) SERCA2 and type-1 Ins(1,4,5)P3 receptor reside either in the same or two tightly associated subcellular compartments.
  • Favre-Nicolin, V., et al. (författare)
  • Analysis of strain and stacking faults in single nanowires using Bragg coherent diffraction imaging
  • 2010
  • Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 12
  • Tidskriftsartikel (refereegranskat)abstract
    • Coherent diffraction imaging (CDI) on Bragg reflections is a promising technique for the study of three-dimensional (3D) composition and strain fields in nanostructures, which can be recovered directly from the coherent diffraction data recorded on single objects. In this paper, we report results obtained for single homogeneous and heterogeneous nanowires with a diameter smaller than 100 nm, for which we used CDI to retrieve information about deformation and faults existing in these wires. We also discuss the influence of stacking faults, which can create artefacts during the reconstruction of the nanowire shape and deformation.
  • Jorgensen, J. K., et al. (författare)
  • The ALMA Protostellar Interferometric Line Survey (PILS) First results from an unbiased submillimeter wavelength line survey of the Class 0 protostellar binary IRAS 16293-2422 with ALMA J.
  • 2016
  • Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746.
  • Tidskriftsartikel (refereegranskat)abstract
    • Context. The inner regions of the envelopes surrounding young protostars are characterized by a complex chemistry, with prebiotic molecules present on the scales where protoplanetary disks eventually may form. The Atacama Large Millimeter/submillimeter Array (ALMA) provides an unprecedented view of these regions zooming in on solar system scales of nearby protostars and mapping the emission from rare species. Aims. The goal is to introduce a systematic survey, the Protostellar Interferometric Line Survey (PILS), of the chemical complexity of one of the nearby astrochemical templates, the Class 0 protostellar binary IRAS 16293−2422, using ALMA in order to understand the origin of the complex molecules formed in its vicinity. In addition to presenting the overall survey, the analysis in this paper focuses on new results for the prebiotic molecule glycolaldehyde, its isomers, and rarer isotopologues and other related molecules. Methods. An unbiased spectral survey of IRAS 16293−2422 covering the full frequency range from 329 to 363 GHz (0.8 mm) has been obtained with ALMA, in addition to a few targeted observations at 3.0 and 1.3 mm. The data consist of full maps of the protostellar binary system with an angular resolution of 0.5?? (60 AU diameter), a spectral resolution of 0.2 km s−1, and a sensitivity of 4−5 mJy beam−1 km s−1, which is approximately two orders of magnitude better than any previous studies. Results. More than 10 000 features are detected toward one component in the protostellar binary, corresponding to an average line density of approximately one line per 3 km s−1. Glycolaldehyde; its isomers, methyl formate and acetic acid; and its reduced alcohol, ethylene glycol, are clearly detected and their emission well-modeled with an excitation temperature of 300 K. For ethylene glycol both lowest state conformers, aGg? and gGg?, are detected, the latter for the first time in the interstellar medium (ISM). The abundance of glycolaldehyde is comparable to or slightly larger than that of ethylene glycol. In comparison to the Galactic Center these two species are over-abundant relative to methanol, possibly an indication of formation of the species at low temperatures in CO-rich ices during the infall of the material toward the central protostar. Both 13C and the deuterated isotopologues of glycolaldehyde are detected, also for the first time ever in the ISM. For the deuterated species, a D/H ratio of≈5% is found with no differences between the deuteration in the different functional groups of glycolaldehyde, in contrast to previous estimates for methanol and recent suggestions of significant equilibration between water and -OH functional groups at high temperatures. Measurements of the 13C-species lead to a 12C:13C ratio of ≈30, lower than the typical ISM value. This low ratio may reflect an enhancement of 13CO in the ice due to either ion-molecule reactions in the gas before freeze-out or to differences in the temperatures where 12CO and 13CO ices sublimate. Conclusions. The results reinforce the importance of low-temperature grain surface chemistry for the formation of prebiotic molecules seen here in the gas after sublimation of the entire ice mantle. Systematic surveys of the molecules thought to be chemically related, as well as the accurate measurements of their isotopic composition, hold strong promise for understanding the origin of prebiotic molecules in the earliest stages of young stars.
  • Lykke, J. M., et al. (författare)
  • The ALMA-PILS survey: First detections of ethylene oxide, acetone and propanal toward the low-mass protostar IRAS 16293-2422
  • 2017
  • Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 597, s. A53-
  • Tidskriftsartikel (refereegranskat)abstract
    • Context. One of the open questions in astrochemistry is how complex organic and prebiotic molecules are formed. The unsurpassed sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA) takes the quest for discovering molecules in the warm and dense gas surrounding young stars to the next level. Aims. Our aim is to start the process of compiling an inventory of oxygen-bearing complex organic molecules toward the solar-type Class 0 protostellar binary IRAS 16293-2422 from an unbiased spectral survey with ALMA, Protostellar Interferometric Line Survey (PILS). Here we focus on the new detections of ethylene oxide (c-C2H4O), acetone (CH3COCH3), and propanal (C2H5CHO). Methods. With ALMA, we surveyed the spectral range from 329 to 363 GHz at 0.5? (60 AU diameter) resolution. Using a simple model for the molecular emission in local thermodynamical equilibrium, the excitation temperatures and column densities of each species were constrained. Results. We successfully detect propanal (44 lines), ethylene oxide (20 lines) and acetone (186 lines) toward one component of the protostellar binary, IRAS 16293B. The high resolution maps demonstrate that the emission for all investigated species originates from the compact central region close to the protostar. This, along with a derived common excitation temperature of Tex ? 125 K, is consistent with a coexistence of these molecules in the same gas. Conclusions. The observations mark the first detections of acetone, propanal and ethylene oxide toward a low-mass protostar. The relative abundance ratios of the two sets of isomers, a CH3COCH3/C2H5CHO ratio of 8 and a CH3CHO/c-C2H4O ratio of 12, are comparable to previous observations toward high-mass protostars. The majority of observed abundance ratios from these results as well as those measured toward high-mass protostars are up to an order of magnitude above the predictions from chemical models. This may reflect either missing reactions or uncertain rates in the chemical networks. The physical conditions, such as temperatures or densities, used in the models, may not be applicable to solar-type protostars either.
  • Oppenheim, Rebecca D., et al. (författare)
  • BCKDH : the missing link in apicomplexan mitochondrial metabolism is required for full virulence of Toxoplasma gondii and Plasmodium berghei
  • 2014
  • Ingår i: PLoS Pathogens. - : PLOS. - 1553-7366 .- 1553-7374. ; 10:7
  • Tidskriftsartikel (refereegranskat)abstract
    • While the apicomplexan parasites Plasmodium falciparum and Toxoplasma gondii are thought to primarily depend on glycolysis for ATP synthesis, recent studies have shown that they can fully catabolize glucose in a canonical TCA cycle. However, these parasites lack a mitochondrial isoform of pyruvate dehydrogenase and the identity of the enzyme that catalyses the conversion of pyruvate to acetyl-CoA remains enigmatic. Here we demonstrate that the mitochondrial branched chain ketoacid dehydrogenase (BCKDH) complex is the missing link, functionally replacing mitochondrial PDH in both T. gondii and P. berghei. Deletion of the E1a subunit of T. gondii and P. berghei BCKDH significantly impacted on intracellular growth and virulence of both parasites. Interestingly, disruption of the P. berghei E1a restricted parasite development to reticulocytes only and completely prevented maturation of oocysts during mosquito transmission. Overall this study highlights the importance of the molecular adaptation of BCKDH in this important class of pathogens.
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