Search Results - (Author, Cooperation:C. Duque)

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  1. 1
    D. Reich ; N. Patterson ; D. Campbell ; A. Tandon ; S. Mazieres ; N. Ray ; M. V. Parra ; W. Rojas ; C. Duque ; N. Mesa ; L. F. Garcia ; O. Triana ; S. Blair ; A. Maestre ; J. C. Dib ; C. M. Bravi ; G. Bailliet ; D. Corach ; T. Hunemeier ; M. C. Bortolini ; F. M. Salzano ; M. L. Petzl-Erler ; V. Acuna-Alonzo ; C. Aguilar-Salinas ; S. Canizales-Quinteros ; T. Tusie-Luna ; L. Riba ; M. Rodriguez-Cruz ; M. Lopez-Alarcon ; R. Coral-Vazquez ; T. Canto-Cetina ; I. Silva-Zolezzi ; J. C. Fernandez-Lopez ; A. V. Contreras ; G. Jimenez-Sanchez ; M. J. Gomez-Vazquez ; J. Molina ; A. Carracedo ; A. Salas ; C. Gallo ; G. Poletti ; D. B. Witonsky ; G. Alkorta-Aranburu ; R. I. Sukernik ; L. Osipova ; S. A. Fedorova ; R. Vasquez ; M. Villena ; C. Moreau ; R. Barrantes ; D. Pauls ; L. Excoffier ; G. Bedoya ; F. Rothhammer ; J. M. Dugoujon ; G. Larrouy ; W. Klitz ; D. Labuda ; J. Kidd ; K. Kidd ; A. Di Rienzo ; N. B. Freimer ; A. L. Price ; A. Ruiz-Linares
    Nature Publishing Group (NPG)
    Published 2012
    Staff View
    Publication Date:
    2012-07-18
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Keywords:
    Americas ; Asia ; Cluster Analysis ; Emigration and Immigration/*history/statistics & numerical data ; Gene Flow ; Genetics, Population ; History, Ancient ; Humans ; Indians, North American/*genetics/*history ; Models, Genetic ; *Phylogeny ; Polymorphism, Single Nucleotide/genetics ; Siberia
    Published by:
    http://www.nature.com/

    Latest Papers from Table of Contents or Articles in Press
  2. 2
    Montes, A. ; Duque, C. A.

    [S.l.] : American Institute of Physics (AIP)
    Published 1997
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    Using a variational procedure, within the effective mass-approximation, we calculate the binding energy of a shallow-donor impurity in a rectangular cross-sectional area of a GaAs quantum-well wire, under the action of an electric field applied perpendicular to one of the interfaces, assuming an infinite-confinement potential. We study the binding energy of the donor impurity as a function of the system geometry, the applied electric field, and the donor-impurity position. It was found that the presence of the electric field breaks down the degeneracy of the states for impurities symmetrically positioned within the structure. Our results for a large length of one side of the cross-sectional area coincide quite well with previous results in quantum wells. We show, unambiguously, that the impurity binding energy depends strongly not only on quantum confinement, but also on the applied electric field and on the distribution of impurities inside the quantum-well wires; these aspects must be taken into account in the quantitative understanding of optical phenomena related to shallow impurities when an electric field is applied. © 1997 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.365362

    Articles: DFG German National Licenses
  3. 3
    Montes, A. ; Duque, C. A.

    [S.l.] : American Institute of Physics (AIP)
    Published 1998
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    We present a study of the role of the electric field on the binding energy of the ground and first few excited states of a shallow impurity in a rectangular cross-sectional area vacuum/GaAs/vacuum quantum-well wire (QWW), where the electric field is applied perpendicular to the symmetry axis of the wire. Using the effective-mass approximation within a variational scheme we calculate the binding energy of the 1s-like ground state as well as that of some excited states (2s-, 2px-, and 2pz-like) as a function of the geometry, applied electric field, and donor-impurity position. We found that the presence of the electric field breaks down the degeneracy of states for impurities symmetrically positioned within the structure, and that the geometric confinement and the electric field are determinant for the existence of bound excited states in these structures. Future interpretations of optical phenomena related with shallow donor impurities in vacuum/GaAs/vacuum QWWs, in which the effects of an applied electric field competes with the quantum confinement, must take into consideration these results. © 1998 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.368176

    Articles: DFG German National Licenses
  4. 4
    Duque, C. A.

    [S.l.] : American Institute of Physics (AIP)
    Published 1998
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    A theoretical study of the photoluminescence spectra associated with free-carrier to acceptor-impurity recombination in quantum-size GaAs wire crystals is presented. We model the actual GaAs quantum wires via GaAs low-dimensional systems with finite cylindrical shape and hard-wall boundaries. The acceptor states are described within a variational scheme in the effective-mass approximation. The photoluminescence spectra associated with free carriers recombining with acceptor states are calculated for a homogeneous distribution of acceptor impurities within the low-dimensional heterostructure. We found that for a system whose length is comparable to the radius the photoluminescence line shape shows three structures associated with impurities located at special regions in the heterostructure, whereas for a system whose length is much larger than the radius we obtain two well-defined peaks, associated with acceptors either at the center position or the edge position in the low-dimensional system. Both the peak positions and relative intensities are in good agreement with spectral features present in experimental data on GaAs quantum-wire microcrystals. © 1998 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1063/1.367494

    Articles: DFG German National Licenses
  5. 5
    Staff View
    ISSN:
    0006-291X
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Biology
    Chemistry and Pharmacology
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1016/S0006-291X(78)80045-X

    Articles: DFG German National Licenses
  6. 6
    Staff View
    ISSN:
    0006-291X
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Biology
    Chemistry and Pharmacology
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1016/S0006-291X(78)80045-X

    Articles: DFG German National Licenses
  7. 7
    Duque, C. ; Morisaki, M. ; Ikekawa, N. ; Shikita, M.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0006-291X
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Biology
    Chemistry and Pharmacology
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1016/0006-291X(78)90593-4

    Articles: DFG German National Licenses
  8. 8
    Staff View
    ISSN:
    0308-521X
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1016/0308-521X(89)90002-4

    Articles: DFG German National Licenses
  9. 9
    Duque, C. ; Morisaki, M. ; Ikekawa, N. ; Shikita, M.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0040-4039
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Chemistry and Pharmacology
    Type of Medium:
    Electronic Resource
    URL:
    http://linkinghub.elsevier.com/retrieve/pii/S0040-4039(01)86624-7

    Articles: DFG German National Licenses
  10. 10
    Staff View
    ISSN:
    1432-1920
    Keywords:
    Key words Anaesthesia ; spinal ; complications ; Haematoma
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Medicine
    Notes:
    Abstract We report two cases of hyperacute spinal subdural haematoma secondary to lumbar spinal anaesthesia, identified with MRI. Prompt diagnosis of this infrequent, potentially serious complication of spinal anaesthesia is essential, as early surgical evacuation may be needed. Suggestive MRI findings in this early phase include diffuse occupation filling of the spinal canal with poor delineation of the spinal cord on T1-weighted images, and a poorly-defined high-signal lesion with a low-signal rim on T2-weighted images.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/s002340050866

    Articles: DFG German National Licenses