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Sökning: WFRF:(Le Guen M)

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1.
  • Ageron, M., et al. (författare)
  • ANTARES : The first undersea neutrino telescope
  • 2011
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 656:1, s. 11-38
  • Tidskriftsartikel (refereegranskat)abstract
    • The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Telescope in the Mediterranean Sea. The main purpose of the detector is to perform neutrino astronomy and the apparatus also offers facilities for marine and Earth sciences. This paper describes the design, the construction and the installation of the telescope in the deep sea, offshore from Toulon in France. An illustration of the detector performance is given. (C) 2011 Elsevier B.V. All rights reserved.
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2.
  • Ageron, M., et al. (författare)
  • Studies of a full-scale mechanical prototype line for the ANTARES neutrino telescope and tests of a prototype instrument for deep-sea acoustic measurements
  • 2007
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 581:3, s. 695-708
  • Tidskriftsartikel (refereegranskat)abstract
    • full-scale mechanical prototype line was deployed to a depth of 2500 m to test the leak tightness of the electronics containers and the pressure-resistant properties of an electromechanical cable under evaluation for use in the ANTARES deep-sea neutrino telescope. During a month-long immersion study, line parameter data were taken using miniature autonomous data loggers and shore-based optical time domain reflectometry. Details of the mechanical prototype line, the electromechanical cable and data acquisition are presented. Data taken during the immersion study revealed deficiencies in the pressure resistance of the electromechanical cable terminations at the entry points to the electronics containers. The improvements to the termination, which have been integrated into subsequent detection lines, are discussed. The line also allowed deep-sea acoustic measurements with a prototype hydrophone system. The technical setup of this system is described, and the first results of the data analysis are presented. (c) 2007 Elsevier B.V. All rights reserved.
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3.
  • Ageron, M., et al. (författare)
  • The ANTARES optical beacon system
  • 2007
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 578:3, s. 498-509
  • Tidskriftsartikel (refereegranskat)abstract
    • ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three-dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular, when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented. (C) 2007 Elsevier B.V. All rights reserved.
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4.
  • Aguilar, J. A., et al. (författare)
  • First results of the instrumentation line for the deep-sea ANTARES neutrino telescope
  • 2006
  • Ingår i: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 26:4-5, s. 314-324
  • Tidskriftsartikel (refereegranskat)abstract
    • In 2005, the ANTARES Collaboration deployed and operated at a depth of 2500 m a so-called Mini Instrumentation Line equipped with Optical Modules (MILOM) at the ANTARES site. The various data acquired during the continuous operation from April to December 2005 of the MILOM confirm the satisfactory performance of the Optical Modules, their front-end electronics and readout system. as well as the calibration devices of the detector. The in situ measurement of the Optical Module time response yields a resolution better than 0.5 ns. The performance of the acoustic positioning system, which enables the spatial reconstruction of the ANTARES detector with a precision of about 10 cm, is verified. These results demonstrate that with the full ANTARES neutrino telescope the design angular resolution of better than 0.3 degrees can be realistically achieved.
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5.
  • Aguilar, J. A., et al. (författare)
  • The data acquisition system for the ANTARES neutrino telescope
  • 2007
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 570:1, s. 107-116
  • Tidskriftsartikel (refereegranskat)abstract
    • The ANTARES neutrino telescope is being constructed in the Mediterranean Sea. It consists of a large three-dimensional array of photo-multiplier tubes. The data acquisition system of the detector takes care of the digitisation of the photo-multiplier tube signals, data transport, data filtering, and data storage. The detector is operated using a control program interfaced with all elements. The design and the implementation of the data acquisition system are described. (c) 2006 Elsevier B.V. All rights reserved.
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6.
  • Aguilar, J A, et al. (författare)
  • Study of large hemispherical photomultiplier tubes for the ANTARES neutrino telescope
  • 2005
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 555:1-2, s. 132-141
  • Tidskriftsartikel (refereegranskat)abstract
    • The ANTARES neutrino telescope, to be immersed depth in the Mediterranean Sea, will consist of a three-dimensional matrix of 900 large area photomultiplier tubes housed in pressure-resistant glass spheres. The selection of the optimal photomultiplier was a critical step for the project and required an intensive phase of tests and developments carried out in close collaboration with the main manufacturers worldwide. This paper provides an overview of the tests performed by the collaboration and describes in detail the features of the photomultiplier tube chosen for ANTARES. (c) 2005 Elsevier B.V. All rights reserved.
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7.
  • Aguilar, J A, et al. (författare)
  • Transmission of light in deep sea water at the site of the ANTARES neutrino telescope
  • 2005
  • Ingår i: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 23:1, s. 131-155
  • Tidskriftsartikel (refereegranskat)abstract
    • The ANTARES neutrino telescope is a large photomultiplier array designed to detect neutrino-induced upward-going muons by their Cherenkov radiation. Understanding the absorption and scattering of light in the deep Mediterranean is fundamental to optimising the design and performance of the detector. This paper presents measurements of blue and UV light transmission at the ANTARES site taken between 1997 and 2000. The derived values for the scattering length and the angular distribution of particulate scattering were found to be highly correlated, and results are therefore presented in terms of an absorption length;,ab, and an effective scattering length lambda(sct)(eff). The values for blue (UV) light are found to be lambda(abs) similar or equal to 60(26) m, lambda(sct)(eff similar or equal to) 265(122) m, with significant (similar to15%) time variability. Finally, the results of ANTARES simulations showing the effect of these water properties on the anticipated performance of the detector are presented. (C) 2004 Elsevier B.V. All rights reserved.
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9.
  • Belloy, Michael E., et al. (författare)
  • Challenges at the APOE locus : a robust quality control approach for accurate APOE genotyping
  • 2022
  • Ingår i: Alzheimer's Research & Therapy. - : Springer Nature. - 1758-9193. ; 14:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Genetic variants within the APOE locus may modulate Alzheimer's disease (AD) risk independently or in conjunction with APOE*2/3/4 genotypes. Identifying such variants and mechanisms would importantly advance our understanding of APOE pathophysiology and provide critical guidance for AD therapies aimed at APOE. The APOE locus however remains relatively poorly understood in AD, owing to multiple challenges that include its complex linkage structure and uncertainty in APOE*2/3/4 genotype quality. Here, we present a novel APOE*2/3/4 filtering approach and showcase its relevance on AD risk association analyses for the rs439401 variant, which is located 1801 base pairs downstream of APOE and has been associated with a potential regulatory effect on APOE.Methods: We used thirty-two AD-related cohorts, with genetic data from various high-density single-nucleotide polymorphism microarrays, whole-genome sequencing, and whole-exome sequencing. Study participants were filtered to be ages 60 and older, non-Hispanic, of European ancestry, and diagnosed as cognitively normal or AD (n = 65,701). Primary analyses investigated AD risk in APOE*4/4 carriers. Additional supporting analyses were performed in APOE*3/4 and 3/3 strata. Outcomes were compared under two different APOE*2/3/4 filtering approaches.Results: Using more conventional APOE*2/3/4 filtering criteria (approach 1), we showed that, when in-phase with APOE*4, rs439401 was variably associated with protective effects on AD case-control status. However, when applying a novel filter that increases the certainty of the APOE*2/3/4 genotypes by applying more stringent criteria for concordance between the provided APOE genotype and imputed APOE genotype (approach 2), we observed that all significant effects were lost. Conclusions: We showed that careful consideration of APOE genotype and appropriate sample filtering were crucial to robustly interrogate the role of the APOE locus on AD risk. Our study presents a novel APOE filtering approach and provides important guidelines for research into the APOE locus, as well as for elucidating genetic interaction effects with APOE*2/3/4.
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11.
  • Le Guen, K, et al. (författare)
  • Development of a four-element conical electron lens dedicated to high resolution Auger electron-ion(s) coincidence experiments
  • 2002
  • Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 73:11, s. 3885-3894
  • Tidskriftsartikel (refereegranskat)abstract
    • A four-element conical electron lens has been developed in view of its integration to a double toroidal electron energy analyzer (DTA) dedicated to Auger electron-ion coincidence measurements. The lens design, using electron trajectory numerical simulations, was entirely guided by the perspective of analyzing energetic electrons with high resolution in the multicoincidence regime. The design, construction, and experimental characterization stages of this electron optics system are described in this article. Emphasis is put on the importance of third generation synchrotron radiation sources when performing such multicoincidence experiments.
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12.
  • Le Guen, K, et al. (författare)
  • Influence of formation path on the CH2BrCl2+ dissociation dynamics
  • 2005
  • Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 123:8
  • Tidskriftsartikel (refereegranskat)abstract
    • To get further insight into the CH2BrCl site-selective fragmentation previously observed upon inner-shell ionization, we have performed high-resolution Br 3d and Cl 2p Auger and spin-orbit resolved Br 3d Auger spectra, and studied the dissociation properties of the CH2BrCl2+ dication formed at threshold by means of threshold electron pair-ion coincidence measurements. The key point is that the origin of site-specific bond breaking is found in the Auger decay itself, as it preferentially populates selected dication states. Whereas the predominance of the C-Br bond breaking is observed in both threshold and inner-shell studies, no signature of selective C-Cl rupture is reported for the dication formed at threshold.
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14.
  • Le Guen, K., et al. (författare)
  • H2S ultrafast dissociation probed by energy-selected resonant Auger electron–ion coincidence measurements
  • 2007
  • Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 127:11, s. 114315-
  • Tidskriftsartikel (refereegranskat)abstract
    • We have studied the ultrafast dissociation of the H2S molecule upon S 2p(3/2)-> 6a(1) inner-shell excitation by combining high-resolution resonant Auger spectroscopy and energy-selected Auger electron-ion coincidence measurements. Auger final states have been correlated to the different fragmentation pathways (S+, HS+, and H2S+ ions). As an original result, we evidence a three-step mechanism to describe the resonant production of S+: the Auger recombination in the HS* fragment is followed for the A (3)Pi and c (1)Pi states by the S++H fragmentation mechanism.
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15.
  • Le Guen, Yann, et al. (författare)
  • Multiancestry analysis of the HLA locus in Alzheimer's and Parkinson's diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes.
  • 2023
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences (PNAS). - 1091-6490 .- 0027-8424. ; 120:36
  • Tidskriftsartikel (refereegranskat)abstract
    • Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinson's disease (PD) and Alzheimer's disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased Aβ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues.
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