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1. Influence of Chemical Composition Variations on Densification During the Sintering of MOX Materials

Author

S. Vaudez, J. Lechelle, and C. Marlot

Subjects
010302 applied physics, Materials science, Reducing atmosphere, Metallurgy, General Engineering, Oxide, chemistry.chemical_element, Sintering, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, chemistry.chemical_compound, chemistry, Impurity, 0103 physical sciences, Oxygen Measurement, Dilatometer, Composite material, 0210 nano-technology, Carbon, MOX fuel
Abstract

The mixed uranium-plutonium oxide (MOX) fabrication process is based on the preparation of UO2 and PuO2 powders. The mixture is pelletized before being sintered at 1973 K (1700 °C) in a reducing atmosphere of Ar/4pctH2/H2O. This paper shows how the densification of MOX fuel is affected during sintering by the moisture content of the gas, the plutonium content of the fuel, and the carbon impurity content in the raw materials. MOX densification can be monitored through dilatometric measurements and gas releases can be continuously analyzed during sintering in terms of their quantity and quality. Variations in the oxygen content in the fuel can be continuously recorded by coupling the dilatometer furnace with an oxygen measurement at the gas outlet. Any carbon-bearing species released, such as CO, can be also linked to densification phenomena when a gas chromatograph is installed at the outlet of the dilatometer. Recommendations on the choice of sintering atmosphere that best optimizes the fuel characteristics have been given on the basis of the results reported in this paper.

Published
2016

2. GriF: The New Three‐dimensional Spectroscopic Mode of PUEO, the Canada‐France‐Hawaii Telescope Adaptive Optics Bonnette: First Observations in the Fabry‐Pérot Scanning Mode

Author

C. Marlot, Francois Lacombe, J. L. Beuzit, A. Chalabaev, B. Grundseth, E. Le Coarer, T. Forveille, Philippe Vallée, James D. Thomas, Robin Arsenault, Daniel Rouan, Olivier Lai, Gilles Joncas, C. Delage, Patrick Rabou, and Y. Clénet

Subjects
Physics, biology, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, biology.organism_classification, law.invention, Grism, Telescope, Interferometry, Optics, Space and Planetary Science, law, K band, Angular resolution, Pueo, Adaptive optics, business, Astrophysics::Galaxy Astrophysics, Fabry–Pérot interferometer, Remote sensing
Abstract

Three‐dimensional spectroscopy has the advantage of providing (quasi‐) simultaneously both spatial and spectral information. Coupled to adaptive optics, it conjugates spectroscopic power with high angular resolution. GriF offers these capabilities in the near‐infrared. As a new observing mode of KIR, the camera behind PUEO, the Canada‐France‐Hawaii Telescope adaptive optics bonnette, it provides images at the diffraction limit of the telescope in the K band. Spectroscopy at a resolution of 2000 is provided by a Fabry‐Perot interferometer coupled with a grism, cooled to limit the background. This setup offers a large multiplex gain by observing simultaneously up to five monochromatic images. This article first describes the instrument and the calibration procedures. Next, we demonstrate GriF performances from its first observations, obtained on the Orion molecular cloud OMC‐1.

Published
2002

3. K2-29 b/WASP-152 b: AN ALIGNED AND INFLATED HOT JUPITER IN A YOUNG VISUAL BINARY

Author

A. Santerne, G. Hébrard, J. Lillo-Box, D. J. Armstrong, S. C. C. Barros, O. Demangeon, D. Barrado, A. Debackere, M. Deleuil, E. Delgado Mena, M. Montalto, D. Pollacco, H. P. Osborn, S. G. Sousa, L. Abe, V. Adibekyan, J.-M. Almenara, P. André, G. Arlic, G. Barthe, P. Bendjoya, R. Behrend, I. Boisse, F. Bouchy, H. Boussier, M. Bretton, D. J. A. Brown, B. Carry, A. Cailleau, E. Conseil, G. Coulon, B. Courcol, B. Dauchet, J.-C. Dalouzy, M. Deldem, O. Desormières, P. Dubreuil, J.-M. Fehrenbach, S. Ferratfiat, R. Girelli, J. Gregorio, S. Jaecques, F. Kugel, J. Kirk, O. Labrevoir, J.-C. Lachurié, K. W. F. Lam, P. Le Guen, P. Martinez, L. P. A. Maurin, J. McCormac, J-B. Pioppa, U. Quadri, A. Rajpurohit, J. Rey, J.-P. Rivet, R. Roy, N. C. Santos, F. Signoret, L. Strabla, O. Suarez, D. Toublanc, M. Tsantaki, J.-M. Vienney, P. A. Wilson, M. Bachschmidt, F. Colas, O. Gerteis, P. Louis, J.-C. Mario, C. Marlot, J. Montier, V. Perroud, V. Pic, D. Romeuf, S. Ubaud, D. Verilhac, Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto = University of Porto, Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Virologia, Laboratorio Nacional de Investigacao Veterinaria (LNIV), Université Paris-Sud - Paris 11 (UP11), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Departamento de Astrofisica [Madrid], Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Calar Alto Observatory, Centro Astronómico Hispano-Alemán, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Instituto de Astrofisica de Canarias (IAC), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Geneva Observatory, University of Geneva [Switzerland], CdR & CdL group, Observatoire de Haute-Provence (OHP), Institut Pythéas (OSU PYTHEAS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Observatoire Chante-Perdrix, School of Physics and Astronomy [Cardiff], Cardiff University, Hôpital Européen Georges Pompidou [APHP] (HEGP), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Département RadioChimie et Procédés (DRCP), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Laval [Québec] (ULaval), Departamento de Física e Astronomia [Porto] (DFA/FCUP), Faculdade de Ciências da Universidade do Porto (FCUP), Universidade do Porto = University of Porto-Universidade do Porto = University of Porto, Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Courbes de rotation d'astéroïdes, de comètes et d'étoiles variables (CdR & CdL group), Universidade do Porto [Porto], Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut de Recherche pour le Développement (IRD), PSL Research University (PSL)-PSL Research University (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), School of Physics and Astronomy, Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Laval, Departamento de Física e Astronomia [Porto], Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centro de Astrofísica da Universidade do Porto ( CAUP ), Institut d'Astrophysique de Paris ( IAP ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Université Paris-Sud - Paris 11 ( UP11 ), Institut d'astrophysique spatiale ( IAS ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), LAEX, Depto. Astrofísica, Centro de Astrobiología, Laboratoire d'Astrophysique de Marseille ( LAM ), Aix Marseille Université ( AMU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National d'Etudes Spatiales ( CNES ) -Centre National de la Recherche Scientifique ( CNRS ), Joseph Louis LAGRANGE ( LAGRANGE ), Université Nice Sophia Antipolis ( UNS ), Université Côte d'Azur ( UCA ) -Université Côte d'Azur ( UCA ) -Observatoire de la Côte d'Azur, Université Côte d'Azur ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Instituto de Astrofisica de Canarias ( IAC ), Astrophysique Interactions Multi-échelles ( AIM - UMR 7158 - UMR E 9005 ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Paris Diderot - Paris 7 ( UPD7 ), Université Côte d'Azur ( UCA ), Observatoire de Haute-Provence ( OHP ), Institut Pythéas ( OSU PYTHEAS ), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ) -Institut de Recherche pour le Développement ( IRD ) -Aix Marseille Université ( AMU ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ) -Institut de Recherche pour le Développement ( IRD ) -Aix Marseille Université ( AMU ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de Mécanique Céleste et de Calcul des Ephémérides ( IMCCE ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université de Lille-Centre National de la Recherche Scientifique ( CNRS ), School of Physis & Astronomy, Hôpital Européen Georges Pompidou [APHP] ( HEGP ), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux ( EPOC ), Observatoire aquitain des sciences de l'univers ( OASU ), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -École pratique des hautes études ( EPHE ) -Centre National de la Recherche Scientifique ( CNRS ), Département RadioChimie et Procédés ( DRCP ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), Centre d'étude spatiale des rayonnements ( CESR ), Université Toulouse III - Paul Sabatier ( UPS ), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Courbes de rotation d'astéroïdes, de comètes et d'étoiles variables ( CdR & CdL group ), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Université de Genève = University of Geneva (UNIGE), Environnements et Paléoenvironnements OCéaniques (EPOC), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Universidade do Porto, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Universidade do Porto-Universidade do Porto, Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
Physics, 010308 nuclear & particles physics, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Stellar rotation, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Radius, 01 natural sciences, Stars, Space and Planetary Science, Planet, 0103 physical sciences, Hot Jupiter, Magnitude (astronomy), Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Transit (astronomy), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, QB, Visual binary
Abstract

International audience; In the present paper we report the discovery of a new hot Jupiter, K2-29 b, first detected by the Super-WASP observatory and then by the K2 space mission during its campaign 4. The planet has a period of 3.25 days, a mass of 0.73 +/- 0.04M(sic), and a radius of 1.19 +/- 0.02 R(sic). The host star is a relatively bright (V = 12.5) G7 dwarf with a nearby K5V companion. Based on stellar rotation and the abundance of lithium, we find that the system might be as young as similar to 450 Myr. The observation of the Rossiter-McLaughlin effect shows that the planet is aligned with respect to the stellar spin. Given the deep transit (20 mmag), the magnitude of the star and the presence of a nearby stellar companion, the planet is a good target for both space- and ground-based transmission spectroscopy, in particular in the near-infrared where both stars are relatively bright.

Published
2016

4. Titania's radius and an upper limit on its atmosphere from the September 8, 2001 stellar occultation

Author

Emmanuel Lellouch, F. Díaz, Ph. Dupouy, P. Figuereido, B. Mitchell, C. Birnbaum, W. Sutherland, H. Mendt, C. Labordena, C. Martinez, P. Valdes Sada, F. Schwartz, P. Burlot, E. van Ballegoij, C. Clarasso-Llauger, J.-F. Coliac, C. Sire, R. Jones, M. Kretlow, P. Maley, S. Rivaud, J. Lecacheux, J.M. Winkel, A. Cidadão, C. Saraiva, R. E. Hill, C. Marlot, S. Pau, F. Colas, F. Roques, E. López, C. Marciano, M. Gabaldá-Sánchez, C. Demeautis, P. Coelho, A. Roca, C. Schnabel, Jean-Eudes Arlot, Pedro Ré, R. Gonçalves, R. Hernández, C. Buil, A.J. Elliott, E. Masana, A. Ardanuy, C. Guillén, J.-F. Lecampion, F. Casarramona, William B. Hubbard, X. Simbaña, L. Rivas, L. Omar Porras, H. Callender, E. Brochard, J. L. Ortiz, M. Rapaport, D. Pulupa, A. Peña, J. Gonçalves, G. Sánchez, G. Rau, A. Hernández, B.M. Ewen-Smith, A. Arnal, Pascal Dubreuil, C. Lambin, C. R. Hills, E. Pallo, K. Daiffallah, X. Otazu-Porter, Richard Miles, Ch. Marlot, R. Cósias, S. Radaelli, B. Bayle, V. Ladino, C. Leyrat, P. Rodas, A. Klotz, R. Dusser, J. Clérigo, B. Wilson, E. Bredner, D. Cornwall, D. Ford, O. Labrevoir, D. Fernández, W. Barrow, Erika Castro, Bruno Sicardy, M. Mascaró, O. Chaptal, E. Simian, E. Recalde, B. Stephanus, Ricard Casas, F. Tonel, William Thuillot, V. Desnoux, J. Berthier, C. Oliveira, J. Laurindo Sobrinho, M. Rieugnié, P. Henriquet, J. Piraux, P. Rosenzweig, Steven N. Ward, G. Eleizalde, A. Yajamín, C. Sauzeaud, J. Aloy Doménech, K. Vieira, M. Lavayssière, P. Langlais, T. Rafaelli, G. Bouderand, J. Santiago, R. Delmas, M. Imbert, H. Denzau, J. A. Ros, A. Valencia, T. Lizardo, F. Teodoro de Gois, J. Porto, J. Fulgence, J.-P. Cazard, O. Contreras, F. Moreno, W. Beisker, J. Lockhart, T. Platt, F. Gorry, J. Afonso da Silva Mendes, R. Percz, R. Nunes, E. Guzmán, V. Ferrer, D. Dunham, S. Bumgarner, J. Fernández-Arozena, A.M. Blommers, C. Jasinski, O. Canales-Moreno, C. Reis, L.L. Martín-Rodríguez, M. Joaquim, O. Naranjo, D. Marchais, Thomas Widemann, C. Cremaschini, P.O. Pujat, and C. Cavadore

Subjects
Physics, 010504 meteorology & atmospheric sciences, Uranus, Astronomy, Astronomy and Astrophysics, Solar radius, Radius, Ephemeris, 01 natural sciences, Occultation, Atmosphere, 13. Climate action, Space and Planetary Science, Angular diameter, 0103 physical sciences, Physical Sciences, Polar, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

On September 8, 2001 around 2 h UT, the largest uranian moon, Titania, occulted Hipparcos star 106829 (alias SAO 164538, a V = 7.2 , K0 III star). This was the first-ever observed occultation by this satellite, a rare event as Titania subtends only 0.11 arcsec on the sky. The star's unusual brightness allowed many observers, both amateurs or professionals, to monitor this unique event, providing fifty-seven occultations chords over three continents, all reported here. Selecting the best 27 occultation chords, and assuming a circular limb, we derive Titania's radius: R T = 788.4 ± 0.6 km ( 1 - σ error bar). This implies a density of ρ = 1.711 ± 0.005 g cm −3 using the value G M = ( 2.343 ± 0.006 ) × 10 11 m 3 s −2 derived by Taylor [Taylor, D.B., 1998. Astron. Astrophys. 330, 362–374]. We do not detect any significant difference between equatorial and polar radii, in the limit r eq − r po = − 1.3 ± 2.1 km , in agreement with Voyager limb image retrieval during the 1986 flyby. Titania's offset with respect to the DE405 + URA027 (based on GUST86 theory) ephemeris is derived: Δ α T cos ( δ T ) = − 108 ± 13 mas and Δ δ T = − 62 ± 7 mas (ICRF J2000.0 system). Most of this offset is attributable to a Uranus' barycentric offset with respect to DE405, that we estimate to be: Δ α U cos ( δ U ) = − 100 ± 25 mas and Δ δ U = − 85 ± 25 mas at the moment of occultation. This offset is confirmed by another Titania stellar occultation observed on August 1st, 2003, which provides an offset of Δ α T cos ( δ T ) = − 127 ± 20 mas and Δ δ T = − 97 ± 13 mas for the satellite. The combined ingress and egress data do not show any significant hint for atmospheric refraction, allowing us to set surface pressure limits at the level of 10–20 nbar. More specifically, we find an upper limit of 13 nbar ( 1 - σ level) at 70 K and 17 nbar at 80 K, for a putative isothermal CO2 atmosphere. We also provide an upper limit of 8 nbar for a possible CH4 atmosphere, and 22 nbar for pure N2, again at the 1 - σ level. We finally constrain the stellar size using the time-resolved star disappearance and reappearance at ingress and egress. We find an angular diameter of 0.54 ± 0.03 mas (corresponding to 7.5 ± 0.4 km projected at Titania). With a distance of 170 ± 25 parsecs, this corresponds to a radius of 9.8 ± 0.2 solar radii for HIP 106829, typical of a K0 III giant.

Published
2009

5. Imaging in Orion: NAOS-CONICA Adaptive Optics on the ESO-VLT

Author

M. Gustafsson, C. Marlot, Francois Lacombe, Jean-Louis Lemaire, Eric Gendron, B. Servan, David Mouillet, Anne-Marie Lagrange, Yann Clénet, Gérard Rousset, Daniel Rouan, David Field, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
Physics, biology, Conica, Astronomy, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], biology.organism_classification, Adaptive optics
Abstract

International audience

Published
2005

6. VLT/NACO infrared adaptive optics images of small scale structures in OMC1

Author

F. Lacombe, E. Gendron, D. Rouan, Y. Clénet, D. Field, J. L. Lemaire, M. Gustafsson, A.-M. Lagrange, D. Mouillet, G. Rousset, T. Fusco, L. Rousset-Rouvière, B. Servan, C. Marlot, P. Feautrier, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [Aarhus], Aarhus University [Aarhus], Université de Cergy Pontoise (UCP), Université Paris-Seine, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université Joseph Fourier - Grenoble 1 (UJF), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), université J.Fourier, ONERA, and PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Infrared, [SHS.EDU]Humanities and Social Sciences/Education, ISM: individual objects: OMC1, FOS: Physical sciences, 98.38.Fs, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, law.invention, 010309 optics, Telescope, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SPI]Engineering Sciences [physics], Observatory, law, 0103 physical sciences, ISM: circumstellar matter, Astrophysics::Solar and Stellar Astrophysics, Adaptive optics, 010303 astronomy & astrophysics, Image resolution, Astrophysics::Galaxy Astrophysics, Physics, ISM: kinematics and dynamics, Infrared: ISM, Very Large Telescope, Star formation, Molecular cloud, Astrophysics (astro-ph), Astronomy and Astrophysics, ISM: molecules, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics
Abstract

International audience; Near-infrared observations of line emission from excited H 2 and in the continuum are reported in the direction of the Orion molecular cloud OMC1 , using the European Southern Observatory Very Large Telescope UT4 , equipped with the NAOS adaptive optics system on the CONICA infrared array camera. Spatial resolution has been achieved at close to the diffraction limit of the telescope (0. 08 −0. 12) and images show a wealth of morphological detail. Structure is not fractal but shows two preferred scale sizes of 2. (1100 AU) and 1. 2 (540 AU) , where the larger scale may be associated with star formation. Key words. ISM : individual objects : OMC1 – ISM : circumstellar matter – ISM : kinematics and dynamics – ISM : molecules – infrared : ISM

Published
2004

7. NAOS infrared wavefront sensor design and performance

Author

Julien Charton, Genevieve Michet, Norbert Hubin, V. D. Phan, B. Lefort, Bernard Talureau, Francois Lacombe, Gerard Nicol, Claude Collin, J.-L. Lizon, C. Marlot, Daniel Rouan, Eric Gendron, Sylvain Pau, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Ingénieurs, Techniciens et Administratifs

Subjects
Physics, Wavefront, Pixel, business.industry, Ranging, Field of view, Wavefront sensor, Frame rate, Noise (electronics), chemistry.chemical_compound, Optics, chemistry, Mercury cadmium telluride, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business
Abstract

Only a very few examples of near-infrared wavefront sensors can be found in the litterature. However, none of these sensors provide routine observation yet. Our sensor is the only one to be operated routinely on a large AO system. Entirely cryogenized, this sensor is built around a so-called HAWAII array from Rockwell (HgCdTe, 1024×1024). It is working in the huge spectral band ranging from 0.8 to 2.55 microns, and may use -when required- all the flux from this very whole band. It allows to switch between several optical configurations in order to match all atmospheric and observing conditions, while its original mechanical design allows to keep, even at cryogenic temperatures, a mechanical stability lower than 4 microns in any position. It also has some particular read-out schemes, allowing to obtain frame rates as high as 1200 Hz while keeping a read-out noise performance of 10 electrons rms/pixel. The analysis of the design parameters (pixel size, field of view) is exposed in this article. Some results, obtained during the comissioning runs at ESO, will also be presented.

Published
2003

8. Injection into single mode fibers for OHANA

Author

Bernard Brient, Claude Collin, C. Marlot, Jean Guerin, Jean Cretenet, Denis Ziegler, Jean-Michel Reess, Christophe Berthod, Julien Woillez, Olivier Lai, Guy Perrin, Sylvain Pau, François Reynaud, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Ingénieurs, Techniciens et Administratifs

Subjects
Physics, biology, business.industry, Single-mode optical fiber, biology.organism_classification, law.invention, Telescope, Interferometry, Optics, Mauna kea, law, K band, Fiber, Pueo, Adaptive optics, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

We present preliminary results of injection tests in single mode fibers, conducted in August 2002 at Canada-France-Hawaii Telescope. Single mode fibers for J, H and K band where placed at the focus of the adaptive optics PUEO. The goal of this experiment was to prepare the next step of the OHANA project: an interferometric fiber link between two telescopes on top of Mauna Kea.

Published
2002

9. Interferometric Coupling of the Keck Telescopes with Single-Mode Fibers

Author

Stephen T. Ridgway, F. Dauny, Olivier Guyon, Jean Guerin, J. Gathright, Peter Wizinowich, C. Collin, J. Nishikawa, Francois Rigaut, Katherine C. Roth, M. Hrynevych, D. Ziegler, Guy Perrin, P. Fédou, J. Crétenet, Sébastien Vergnole, Andrew J. Adamson, Laurent Delage, C. Berthod, C. Deléglise, M. Marteaud, B.-T. Melse, Julien Woillez, C. Marlot, Pierre Léna, T. Goeltzenlichter, Takayuki Kotani, D. Le Mignant, Alan T. Tokunaga, B. Brient, R. Hulin, Frederic H. Chaffee, Jean-Michel Reess, Olivier Lai, François Reynaud, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Ingénieurs, Techniciens et Administratifs, W. M. Keck Observatory, Canada-France-Hawaii Telescope Corporation (CFHT), National Research Council of Canada (NRC)-Centre National de la Recherche Scientifique (CNRS)-University of Hawai'i [Honolulu] (UH), Institut de Recherche en Communications Optiques et Microondes (IRCOM), Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), United Kingdom Infra-Red Telescope, Hilo, Division technique INSU/SDU (DTI), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Pôle instrumental, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Subaru Telescope, National Astronomical Observatory of Japan (NAOJ), National Optical Astronomy Observatory, Tucson (NOAO), Gemini Observatory, and Institute for Astronomy, University of Hawaii

Subjects
Coupling, Physics, Multidisciplinary, Wavelength range, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Single-mode optical fiber, Astrophysics::Cosmology and Extragalactic Astrophysics, Interferometry, Optics, Interference (communication), Mauna kea, Observatory, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Astrophysics::Galaxy Astrophysics
Abstract

Here we report successful interferometric coupling of two large telescopes with single-mode fibers. Interference fringes were obtained in the 2- to 2.3-micrometer wavelength range on the star 107 Herculis by using the two Keck 10-meter telescopes, each feeding their common interferometric focus with 300 meters of single-mode fibers. This experiment demonstrates the potential of fibers for future kilometric arrays of telescopes and is the first step toward the 'OHANA (Optical Hawaiian Array for Nanoradian Astronomy) interferometer at the Mauna Kea observatory in Hawaii. It opens the way to sensitive optical imagers with resolutions below 1 milli‐arc second. Our experimental setup can be directly extended to large telescopes separated by many hundreds of meters.

Published
2006

10. Ester synthesis in organic solvent catalyzed by lipases immobilized on hydrophilic supports

Author

J. Baratti, C. Marlot, C. Triantaphylides, and G. Langrand

Subjects
Heptane, biology, Chemistry, Organic solvent, Bioengineering, General Medicine, Butyrate, Applied Microbiology and Biotechnology, Catalysis, Solvent, chemistry.chemical_compound, Adsorption, biology.protein, Organic chemistry, Lipase, Biotechnology
Abstract

Eight microbial lipases and one animal lipase were immobilized on hydrophilic supports either by adsorption or entrapment. All preparations catalyzed the synthesis of geranyl or menthyl butyrate or laurate using heptane as solvent. This is a simple and easy method for ester synthesis.

Published
1985

11. Exemple d’investigation en technologie au collège : ébauche de solutions formelles dans le processus de conception d’une table basse

Author

Laisney, Patrice, Brandt-Pomares, Pascale, Apprentissage, Didactique, Evaluation, Formation (ADEF), Aix Marseille Université (AMU), and C. Marlot & L. Morge

Subjects
Conception Assistée par Ordinateur CAO, [SHS.EDU]Humanities and Social Sciences/Education, Investigation scientifique et technologique, Didactique de la technologie
Abstract

National audience; Comment adapter l'investigation scientifique et technologique aux enseignants ? Comment réduire la difficulté de mise en œuvre de séquences d'investigation sans pour autant affaiblir les enjeux didactiques ? Ce chapitre propose un exemple en technologie au collège. Il s'agit d'une piste qui vise à réduire les difficultés de conception et de mise en œuvre en modifiant certaines variables de la séquence d'investigation. Cette illustration s'appuie sur la volonté de construire des dispositifs permettant à l'élève de conduire sa propre réflexion au travers de la résolution de problèmes "ouverts" sur plusieurs solutions et non pas guidé vers la solution prédéterminée par le professeur. Les élèves ont à concevoir une table basse à l'aide des outils de dessins traditionnels et de CAO.

Published
2016

12. Recherche coopérative et élaboration de ressources pour enseigner le volcanisme en classe de 4e dans le cadre de l'apprentissage par problématisation

Author

Marlot, Corinne, Faidit, Claire, Activité, Connaissance, Transmission, éducation (ACTé), Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Activité, Connaissance, Transmission, éducation (ACTé ), Université Clermont Auvergne (UCA), C. Marlot, and L. Morge

Subjects
[SHS.EDU]Humanities and Social Sciences/Education
Abstract

International audience

Published
2016

13. Culture scientifique et technologique : évaluation PISA

Author

Tiberghien, Andrée, Interactions, Corpus, Apprentissages, Représentations (ICAR), École normale supérieure - Lyon (ENS Lyon)-Université Lumière - Lyon 2 (UL2)-INRP-Ecole Normale Supérieure Lettres et Sciences Humaines (ENS LSH)-Centre National de la Recherche Scientifique (CNRS), C. Marlot & L. Morge, Les auteurs remercient le LABEX ASLAN (ANR-10-LABX-0081) de l'Université de Lyon pour son soutien financier dans le cadre du programme 'Investissements d'Avenir' (ANR-11-IDEX-0007) de l'Etat Français géré par l'Agence Nationale de la Recherche (ANR)., ICAR, Référent HAL, and École normale supérieure de Lyon (ENS de Lyon)-Université Lumière - Lyon 2 (UL2)-INRP-Ecole Normale Supérieure Lettres et Sciences Humaines (ENS LSH)-Centre National de la Recherche Scientifique (CNRS)

Subjects
enseignement, [SHS.LANGUE]Humanities and Social Sciences/Linguistics, [SHS.LANGUE] Humanities and Social Sciences/Linguistics
Abstract

2016a; International audience

Published
2016

14. Interferometric coupling of the Keck telescopes with single-mode fibers.

Author

Perrin G, Woillez J, Lai O, Guérin J, Kotani T, Wizinowich PL, Le Mignant D, Hrynevych M, Gathright J, Léna P, Chaffee F, Vergnole S, Delage L, Reynaud F, Adamson AJ, Berthod C, Brient B, Collin C, Crétenet J, Dauny F, Deléglise C, Fédou P, Goeltzenlichter T, Guyon O, Hulin R, Marlot C, Marteaud M, Melse BT, Nishikawa J, Reess JM, Ridgway ST, Rigaut F, Roth K, Tokunaga AT, and Ziegler D

Abstract

Here we report successful interferometric coupling of two large telescopes with single-mode fibers. Interference fringes were obtained in the 2- to 2.3-micrometer wavelength range on the star 107 Herculis by using the two Keck 10-meter telescopes, each feeding their common interferometric focus with 300 meters of single-mode fibers. This experiment demonstrates the potential of fibers for future kilometric arrays of telescopes and is the first step toward the 'OHANA (Optical Hawaiian Array for Nanoradian Astronomy) interferometer at the Mauna Kea observatory in Hawaii. It opens the way to sensitive optical imagers with resolutions below 1 milli-arc second. Our experimental setup can be directly extended to large telescopes separated by many hundreds of meters.

Published
2006
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15. A limit to the speed of processing in ultra-rapid visual categorization of novel natural scenes.

Author

Fabre-Thorpe M, Delorme A, Marlot C, and Thorpe S

Subjects
Adult, Evoked Potentials physiology, Evoked Potentials, Visual physiology, Female, Humans, Male, Middle Aged, Photic Stimulation, Form Perception physiology, Reaction Time physiology, Visual Pathways physiology
Abstract

The processing required to decide whether a briefly flashed natural scene contains an animal can be achieved in 150 msec (Thorpe, Fize, & Marlot, 1996). Here we report that extensive training with a subset of photographs over a 3-week period failed to increase the speed of the processing underlying such Rapid Visual Categorizations: Completely novel scenes could be categorized just as fast as highly familiar ones. Such data imply that the visual system processes new stimuli at a speed and with a number of stages that cannot be compressed. This rapid processing mode was seen with a wide range of visual complex images, challenging the idea that short reaction times can only be seen with simple visual stimuli and implying that highly automatic feed-forward mechanisms underlie a far greater proportion of the sophisticated image analysis needed for everyday vision than is generally assumed.

Published
2001
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16. Speed of processing in the human visual system.

Author

Thorpe S, Fize D, and Marlot C

Subjects
Adult, Evoked Potentials, Visual, Female, Humans, Male, Middle Aged, Reaction Time, Vision, Ocular physiology
Abstract

How long does it take for the human visual system to process a complex natural image? Subjectively, recognition of familiar objects and scenes appears to be virtually instantaneous, but measuring this processing time experimentally has proved difficult. Behavioural measures such as reaction times can be used, but these include not only visual processing but also the time required for response execution. However, event-related potentials (ERPs) can sometimes reveal signs of neural processing well before the motor output. Here we use a go/no-go categorization task in which subjects have to decide whether a previously unseen photograph, flashed on for just 20 ms, contains an animal. ERP analysis revealed a frontal negativity specific to no-go trials that develops roughly 150 ms after stimulus onset. We conclude that the visual processing needed to perform this highly demanding task can be achieved in under 150 ms.

Published
1996
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17. Near infrared astronomical light collector.

Author

Chevillard JP, Connes P, Cuisenier M, Friteau J, and Marlot C

Abstract

A 4-m aperture light collector has been built using the mosaic principle specifically for high resolution stellar spectroscopy in the near infrared by the Fourier multiplex technique. The most novel feature is complete servo control of all optical elements to bring individual images to a common point. Initial goals were a spectral survey of ir objects, and the testing of techniques for a larger future collector. However, the project has been stopped by lack of interest and support; the finished collector will not be used.

Published
1977
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