5 results
Contributors
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- By Mark S. Aloia, Ellemarije Altena, Peter Anderer, Christopher L. Asplund, Nitin Bangera, Jeroen S. Benjamins, Daniela Berg, Bohdan Bybel, Vincenza Castronovo, Suk-tak Chan, Michael W. L. Chee, Pietro Cortelli, Michael Czisch, Joseph T. Daley, Thien Thanh Dang-Vu, Yazmín de la Garza-Neme, Lourdes DelRosso, Derk-Jan Dijk, Maria Engström, Thorleif Etgen, Bruce J. Fisch, Ariane Foret, Patrice Fort, Steffen Gais, Anne Germain, Jana Godau, Andrew L. Goertzen, William A. Gomes, Ronald M. Harper, Seung Bong Hong, Romy Hoque, Scott A. Huettel, Yuichi Inoue, Alex Iranzo, Mathieu Jaspar, Zayd Jedidi, Alejandro Jiménez-Genchi, Eun Yeon Joo, Gerhard Klösch, Karsten Krakow, Rajesh Kumar, Caroline Kussé, Hans-Peter Landolt, Helmut Laufs, Jeffrey David Lewine, Camilo Libedinsky, Michael L. Lipton, Mordechai Lorberboym, Cheng Luo, Pierre-Hervé Luppi, Paul M. Macey, Pierre Maquet, Laura Mascetti, Christelle Meyer, Sarah Moens, Vincenzo Muto, Shadreck Mzengeza, Eric Nofzinger, Takashi Nomura, Daniela Perani, Jennifer R. Ramautar, Bernd Saletu, Michael T. Saletu, Gerda Saletu-Zyhlarz, Christina Schmidt, Monika Schönauer, Richard J. Schwab, Sophie Schwartz, Keivan Shifteh, Sanjib Sinha, Victor I. Spoormaker, Ryan P. J. Stocker, A. Jon Stoessl, Diederick Stoffers, A. B. Taly, Robert Joseph Thomas, Michael J. Thorpy, Emily Urry, Jason Valerio, Ysbrand D. Van Der Werf, Gilles Vandewalle, Hans P. A. Van Dongen, Eus J. W. Van Someren, Vinod Venkatraman, Frederic von Wegner, Thomas C. Wetter, Dezhong Yao
- Edited by Eric Nofzinger, University of Pittsburgh, Pierre Maquet, Université de Liège, Belgium, Michael J. Thorpy
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- Book:
- Neuroimaging of Sleep and Sleep Disorders
- Published online:
- 05 March 2013
- Print publication:
- 07 March 2013, pp viii-xii
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Spatial quantum search in a triangular network†
- G. ABAL, R. DONANGELO, M. FORETS, R. PORTUGAL
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- Journal:
- Mathematical Structures in Computer Science / Volume 22 / Issue 3 / June 2012
- Published online by Cambridge University Press:
- 09 February 2012, pp. 521-531
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- Article
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The spatial search problem consists of minimising the number of steps required to find a given site in a network, with the restriction that only an oracle query or a translation to a neighbouring site is allowed at each step. We propose a quantum algorithm for the spatial search problem on a triangular lattice with N sites and torus-like boundary conditions. The proposed algorithm is a special case of the general framework for abstract search proposed by Ambainis, Kempe and Rivosh (AKR) in Ambainis et al. (2005) and Tulsi in Tulsi (2008) applied to a triangular network. The AKR–Tulsi formalism was employed to show that the time complexity of the quantum search on the triangular lattice is .
Glitters of Warm H2 in the Cold Interstellar Medium
- M. Giard, F. Casoli, F. Paletou, E. Falgarone, F. Boulanger, F. Combes, L. Verstraete, G. Pineau des Forêts, P. Hily-Blant
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- Journal:
- European Astronomical Society Publications Series / Volume 14 / 2005
- Published online by Cambridge University Press:
- 05 January 2006, pp. 57-66
- Print publication:
- 2005
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We present the scientific case for a high resolution spectro-imager in the mid-IR that would be dedicated to the mapping of H2 emission in its four lowest rotational transitions, at 28.2, 17.0, 12.3 and 9.7 micron with a spectral resolution ~104 sufficient to provide kinematical distances in galaxies. The proposed instrument on a 2 m-class telescope will be most sensitive to H2 line emission simultaneously extended and structured at small scale, in gas at temperatures higher than 80 K. Colder H2, which may contribute most of the baryonic dark matter in galaxies, will be traced by the emission of glitters of warm H2 heated, throughout the medium, by the dissipation of omnipresent turbulence. The main scientific objectives are to (i) directly measure the mass and temperature distribution of the warm H2, far from star forming regions, in particular in low metallicity environments where the traditional tracers of H2 (CO, dust emission) fail, (ii) trace the dissipation of turbulence in the perspective of building a global view of the star formation process in galaxies and (iii) trace baryonic dark matter in the form of cold H2 in a large sample of galaxies along the Hubble sequence.
FUSE and Deuterated Molecular Hydrogen
- from 3 - Observations and Models
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- By R. Ferlet, Institut d'Astrophysique de Paris, CNRS, 98 bis Bld Arago, F-75014 Paris, France, M. André, Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA, G. Hébrard, Institut d'Astrophysique de Paris, CNRS, 98 bis Bld Arago, F-75014 Paris, France, A. Lecavelier, Institut d'Astrophysique de Paris, CNRS, 98 bis Bld Arago, F-75014 Paris, France, M. Lemoine, Observatoire de Paris, 5 place Janssen, F-92195 Meudon cedex, France, G. Pineau des Forêts, Observatoire de Paris, 5 place Janssen, F-92195 Meudon cedex, France, E. Roueff, Observatoire de Paris, 5 place Janssen, F-92195 Meudon cedex, France, A. Vidal-Madjar, Institut d'Astrophysique de Paris, CNRS, 98 bis Bld Arago, F-75014 Paris, France
- Edited by F. Combes, Observatoire de Paris, DEMIRM, G. Pineau des Forets, Observatoire de Paris de Meudon, DAEC
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- Book:
- Molecular Hydrogen in Space
- Published online:
- 04 August 2010
- Print publication:
- 06 November 2000, pp 179-188
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Summary
The Lyman and Werner band systems of deuterated molecular hydrogen (HD) occur in the far UV range below 120 nm. This spectral window is now open at moderate resolution and high sensitivity with the FUSE satellite. FUSE spectra of hot stars with high extinction through translucent clouds will give access to the deuterium abundance inside molecular clouds where D is essentially in the form of HD. Measurement of HD/H2 ratio becomes thus a new powerful method to evaluate the D/H ratio in the interstellar medium.
An example is given with the FUSE spectrum of the high extinction O9III star HD 73882 (EB–V = 0.7). Very preliminary analysis and an estimate of the HD/H2 ratio are presented.
Introduction
It has long been recognized that the primordial abundance of deuterium represents the most sensitive probe of the baryonic density Ωb of the Universe (see, e.g., Schramm & Turner 1998; Olive et al. 1999). On the other hand, abundance of deuterium at any epoch is a lower limit to its primordial abundance, since deuterium is destroyed, not created, in stars of any mass. For this reason, deuterium abundance is also an efficient tracer of the universal star formation rate. Unfortunately, the evolution of deuterium abundance from the primordial to the solar metallicity is still unclear.
Measurements of the atomic D/H ratio have been performed in different astrophysical sites, namely in moderate to high redshift quasar absorbers, in the presolar nebula and in the local interstellar medium (for reviews see, e.g., Ferlet & Lemoine 1996; Linsky 1998; Vidal-Madjar et al. 1998a; Lemoine et al. 1999).
Hydrogen in Photodissociation Regions: NGC2023 and NGC7023
- from 3 - Observations and Models
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- By D. Field, Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark and Observatoire de Paris-Meudon, J. L. Lemaire, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France; Université de Cergy-Pontoise, F-95806 Cergy Cedex, France, J. P. Maillard, Institut d'Astrophysique, 98bis, Boulevard Arago, F-75014 Paris, France, S. Leach, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France, G. Pineau des Forêts, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France, E. Falgarone, Ecole Normale Supérieure, 24 Rue Lhomond, 75231 Paris Cedex 05, France, F. P. Pijpers, Theoretical Astrophysics Centre, University of Aarhus, DK-8000 Aarhus C, Denmark, M. Gerin, Ecole Normale Supérieure, 24 Rue Lhomond, 75231 Paris Cedex 05, France, F. Rostas, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France, D. Rouan, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France, L. Vannier, Observatoire de Paris-Meudon, F-92195 Meudon Principal Cedex, France
- Edited by F. Combes, Observatoire de Paris, DEMIRM, G. Pineau des Forets, Observatoire de Paris de Meudon, DAEC
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- Book:
- Molecular Hydrogen in Space
- Published online:
- 04 August 2010
- Print publication:
- 06 November 2000, pp 155-160
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Summary
High spatial and spectral resolution observations are reported of H2 infrared emission from the reflection nebulæ NGC2023 and NGC7023. The local molecular gas is strongly perturbed by the presence of the massive stars which power these nebulae. Data yield information on the small-scale structure, the temperature and density and the dynamics of the excited gas. Excited material is found to be hot (400-500K), dense (105-106 cm−3) and clumped containing substantial flows and velocity fields.
Introduction
The two reflection nebulæ NGC2023 and NGC7023 are prototypes of regions in which recently formed massive stars are interacting strongly with their parent gas. The outcome of these interactions is important in understanding the cycle of star formation in which massive stars are created and, by perturbing their surroundings, influence the nature of the gas in which future stars may form. The goal of our work is to examine in detail the perturbed gas around massive young stars. Some of the observations of infrared (IR) emission of molecular hydrogen in NGC2023 and NGC7023, performed in recent years in our group, are described below.
Nebulosity in NGC2023 and NGC7023 is excited by B-stars of temperatures respectively 22,000K and 20,400K. The distance between the star and the illuminated surrounding gas is ∼ 0.1 pc in both nebulæ. NGC2023 shows a strong IR excess with emission from small dust particles plus extended red emission, and has an associated molecular cloud with OH, HCHO, HCN, CO, CH, CH+ and other detections (see Field et al. 1994).