5,150 research outputs found
Gender classification of face images: the role of global and feature-based information
Peer reviewe
meson broadening and dilepton production in heavy ion collisions
The modification of the width of the rho meson due to in-medium decays and
collisions is evaluated. In high temperature and/or high density hadronic
matter, the collision width is much larger than the one-loop decay width. The
large width of the meson in matter seems to be consistent with some
current interpretations of the mass spectra measured at the CERN/SPS.Comment: 4 pages, LaTeX, including 4 Postscript figures, to appear in Proc. of
QM'99, Nucl. Phys.
The fossil record of the family Benthopectinidae (Echinodermata, Asteroidea), a reappraisal
Fossils assigned to the predominantly deep-sea asteroid family Benthopectinidae Verrill, 1894 are described and their affinities reappraised. Detailed comparative morphology of ambulacrals, adambulacrals and marginal ossicles has revealed that only some extinct taxa fall within the morphological range of the modern representatives of the family. These include Jurapecten hessi Gale, 2011, J. infrajurensis sp. nov. (both Jurassic), J. dhondtae sp. nov. (Upper Cretaceous) and Nearchaster spinosus (Blake, 1973) comb. nov. (Lower Oligocene). A new Late Cretaceous genus, Punkaster gen. nov. (P. spinifera gen. et sp. nov. and P. ruegenensis gen. et sp. nov.), appears to be a highly derived benthopectinid. A possible benthopectinid is described from the Upper Triassic (Carnian) of China. Other described records are distantly related to, but convergent in gross morphology with, benthopectinids. Thus, Plesiastropecten hallovensis Peyer, 1944 is here referred to the Jurassic spinulosidan family Plumasteridae Gale, 2011 and Xandarosaster hessi Blake, 1984 is interpreted as Spinulosida Perrier, 1884 incertae sedis. The mid-Cretaceous Alkaidia sumralli Blake & Reid, 1998 is reassigned to the Forcipulatida (Zorocallina). The “fossil benthopectinid” of Spencer & Wright in Moore (1966) is shown to belong to the goniopectinid genus Chrispaulia Gale, 2005, of which two new Cretaceous species are described, C. wrightorum sp. nov. and C. spinosa sp. nov. Finally, we consider Henricia? venturana Durham & Roberts, 1948 to be an indeterminate asteroid
Computer simulation of defects and oxygen transport in yttria-stabilized zirconia
We have used molecular dynamics simulations and energy minimization calculations to examine defect energetics and oxygen diffusion in yttria-stabilized zirconia (YSZ). Oxygen vacancies prefer to be second nearest neighbors to yttrium dopants. The oxygen diffusion coefficient shows a peak at 8 mol% yttria consistent with experimental findings. The activation energy for oxygen diffusion varies from 0.6 to 1.0 eV depending on the yttria content. The YZr' VO YZr' complex with a binding energy of -0.85 eV may play an important role in any conductivity degradation of YSZ
Laser surface colouring of titanium for contemporary jewellery
This paper describes work which emerged through a need to understand more about the potential of laser surface engineering for use in the creative industries. The method of creation of contemporary jewellery pieces and the resultant 'Ocular' jewellery series are described from the creative point of view. The work demonstrates how laser controlled oxide growth on Ti–6Al–4V alloy under ambient conditions can be used as an artistic tool by producing precisely defined colours. Use of the method to produce regular areas of even colour and to reproduce freehand drawings on a titanium alloy surface is described. Analysis highlights interference as the main colouring mechanism and suggests a graded surface layer, progressing from an outer layer of TiO2 to lower layers rich in TiO and Ti2O. The model of research by practice presented in this paper offers a contribution to the current debate on partnerships between art and science and engineering
A numerical investigation of a piezoelectric surface acoustic wave interaction with a one-dimensional channel
We investigate the propagation of a piezoelectric surface acoustic wave (SAW)
across a GaAs/AlGaAs heterostructure surface, on which there is
fixed a metallic split-gate. Our method is based on a finite element
formulation of the underlying equations of motion, and is performed in
three-dimensions fully incorporating the geometry and material composition of
the substrate and gates. We demonstrate attenuation of the SAW amplitude as a
result of the presence of both mechanical and electrical gates on the surface.
We show that the incorporation of a simple model for the screening by the
two-dimensional electron gas (2DEG), results in a total electric potential
modulation that suggests a mechanism for the capture and release of electrons
by the SAW. Our simulations suggest the absence of any significant turbulence
in the SAW motion which could hamper the operation of SAW based quantum devices
of a more complex geometry.Comment: 8 pages, 8 figure
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