186,542 research outputs found
Automatic Acquisition of Ranked Qualia Structures from the Web
No full textCimiano P, Wenderoth J. Automatic Acquisition of Ranked Qualia Structures from the Web. In: Carroll JA, van den Bosch A, Zaenen A, eds. ACL 2007, Proceedings of the 45th Annual Meeting of the Association for Computational Linguistics. 2007: 888-895
Intrinsic quantum dots in partially ordered bulk (GaIn)P
No full textWe present a photoluminescence study with 500 nm lateral resolution on partially ordered bulk (GaIn)P alloys at lattice temperatures 3-60 K, external magnetic fields 0-12 T, and excitation power 0.1-100 mu W. In the known ordering-induced low energy emission band we resolve narrow optical transition lines with 0.3-1.0 meV width. They show no thermal broadening, a diamagnetic shift with pronounced anisotropy, and biexci-tonic states. We demonstrate that the transitions are connected with intrinsic quasi-zero-dimensional electron-hole confinement formed at the antiphase-boundaries in the crystal
Directional constraints during bimanual coordination: The interplay between intrinsic and extrinsic directions as revealed by head motions
No full textThe role of directional compatibility was investigated during the production of in-phase and anti-phase coordination patterns involving both arms as well as the head. Our first aim was to compare the quality of coordination between both arms when symmetrical arm posture manipulations were used to disentangle muscle homology from the mutual direction of limb motions in extrinsic space. Findings revealed that in-phase coordination, characterized by the simultaneous activation of homologous muscle groups, was resistant to posture manipulations. Conversely, during anti-phase coordination, the influence of extrinsic direction became more prevalent whereby isodirectionality in extrinsic space contributed to stabilization of anti-phase coordination patterns. The second aim was to study the effect of periodic head movements upon the assembling of a coordinative synergy among the body segments. The findings demonstrated that the in-phase patterns were hardly affected by directionality of head motion. Conversely, the anti-phase patterns were more vulnerable to the directional influence of head movements, showing less accurate and stable coordination during non-isodirectional than isodirectional head motions. These observations underscore the robust nature of coordination patterns based on muscle homology, even in the absence of symmetric arm positions. Moreover, isodirectional head movements became easily integrated with the overall coordination pattern, whereas head-limb coupling was poor when the head moved anti-directional with the limbs. (C) 2007 Elsevier B.V. All rights reserved.Support for the present study was provided through a grant from the Research Council of K.U. Leuven, Belgium (Contract No. OT/03/61) and the Research Programme of the Research Foundation – Flanders (FWO-Vlaanderen G.0460.04 & G.0577.06)
Automatically Learning Qualia Structures from the Web
No full textCimiano P, Wenderoth J. Automatically Learning Qualia Structures from the Web. In: Baldwin T, Korhonen A, Villavicencio A, eds. Proceedings of the ACL Workshop on Deep Lexical Acquisition. Ann Arbor, Michigan: Association for Computational Linguistics; 2005: 28-37
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Connection of anisotropic conductivity to tip-induced space-charge layers in scanning tunneling spectroscopy of p-doped GaAs
No full textThe electronic properties of shallow acceptors in p-doped GaAs{110} are investigated with scanning tunneling microscopy (STM) at low temperature. Shallow acceptors are known to exhibit distinct triangular contrasts in STM images for certain bias voltages. Spatially resolved I(V) spectroscopy is performed to identify their energetic origin and behavior. A crucial parameter-the scanning tunneling microscope tip's work function-is determined experimentally. The voltage dependent potential configuration and band bending situation are derived. Ways to validate the calculations with the experiment are discussed. Differential conductivity maps reveal that the triangular contrasts are only observed with a depletion layer present under the STM tip. The tunnel process leading to the anisotropic contrasts calls for electrons to tunnel through vacuum gap and a finite region in the semiconductor
Asymmetry of acceptor wave functions caused by surface-related strain and electric field in InAs
No full textThe spatial distribution of the local density of states at Mn acceptors near the (110) surface of p-doped InAs is investigated by scanning tunneling microscopy. The shapes of the acceptor contrasts for different dopant depths under the surface are analyzed. Acceptors located within the first ten subsurface layers of the semiconductor show a lower symmetry than expected from theoretical predictions for the bulk acceptor wave function. They exhibit a (001) mirror asymmetry. The degree of asymmetry depends on the acceptor atoms' depths. The measured contrasts for acceptors buried below the tenth subsurface layer closely match the theoretically derived shape. Two effects are able to cause the observed symmetry reduction, i.e., the strain field of the surface relaxation and the tip-induced electric field. While both effects induce similar asymmetries, a comparison of their relative strengths indicates that surface-related strain is the dominant effect for Mn in InAs
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