7,741 research outputs found
Council Regulation 1612/68: A Significant Step in Promoting the Right of Freedom of Movement within the EEC
Discusión sobre el matamorfismo regional del Guadarrama oriental (Sistema Central español)
Se aportan datos que confirman que el metamorfismo del Guadarrama oriental corresponde al tipo distena-sillimanita, con un desarrollo zonal que tiene grandes analogías con el trictaniorfismo barrowiense. Las zonas encontradas: cloritacloritoide-estaurolita-distena-sillimani, y el desarrollo generalizado del almandino en la mayor parte del ámbito metamórfico indican unas condiciones de presión elevada y de un gradiente geotérmico relativamente reducido. Este tipo de sucesión metamórfica es considerablemente diferente del que existe en otros sectores del del Guadarrama central y occidental, donde aparecen tipos de más baja presión y (o) más alta temperatura con andalucita o cordierita como minerales sintomáticos en grados elevados de este metamorfismo.Para este sector no son aceptables muchos de los datos y las conclusiones publicadas por BARD et al. (1970, 1971)
InAs/InP single quantum wire formation and emission at 1.5 microns
Isolated InAs/InP self-assembled quantum wires have been grown using in situ
accumulated stress measurements to adjust the optimal InAs thickness. Atomic
force microscopy imaging shows highly asymmetric nanostructures with average
length exceeding more than ten times their width. High resolution optical
investigation of as-grown samples reveals strong photoluminescence from
individual quantum wires at 1.5 microns. Additional sharp features are related
to monolayer fluctuations of the two dimensional InAs layer present during the
early stages of the quantum wire self-assembling process.Comment: 4 pages and 3 figures submitted to Applied Physics Letter
Discusión sobre el matamorfismo regional del Guadarrama oriental (Sistema Central español)
Se aportan datos que confirman que el metamorfismo del Guadarrama oriental corresponde al tipo distena-sillimanita, con un desarrollo zona1 que tiene grandes analogías con el trictaniorfismo barrowiense. Las zonas encontradas: cloritacloritoide-estaurolita-distena-sillimani, y el desarrollo generalizado del almandino en la mayor parte del ámbito metatii0rfico indican unas condiciones de presión elevada y de un gradiente geotérmico relativamente reducido. Este tipo de sucesión metamórfica es considerablemente diferente del que existe en otros sectores del del Guadarrama central y occidental, donde aparecen tipos de más baja presión y (o) más alta temperatura con andalucita o cordierita como minerales sintomáticos en grados elevados de este metamorfismo. Para este sector no son aceptables muchos de los datos y las conclusiones publicadas por BARD et al. (1970, 1971)
Excitons in coupled InAs/InP self-assembled quantum wires
Optical transitions in coupled InAs/InP self-assembled quantum wires are
studied within the single-band effective mass approximation including effects
due to strain. Both vertically and horizontally coupled quantum wires are
investigated and the ground state, excited states and the photoluminescence
peak energies are calculated. Where possible we compare with available
photo-luminescence data from which it was possible to determine the height of
the quantum wires. An anti-crossing of the energy of excited states is found
for vertically coupled wires signaling a change of symmetry of the exciton
wavefunction. This crossing is the signature of two different coupling regimes.Comment: 8 pages, 8 figures. To appear in Physical Review
A momentum-conserving, consistent, Volume-of-Fluid method for incompressible flow on staggered grids
The computation of flows with large density contrasts is notoriously
difficult. To alleviate the difficulty we consider a consistent mass and
momentum-conserving discretization of the Navier-Stokes equation.
Incompressible flow with capillary forces is modelled and the discretization is
performed on a staggered grid of Marker and Cell type. The Volume-of-Fluid
method is used to track the interface and a Height-Function method is used to
compute surface tension. The advection of the volume fraction is performed
using either the Lagrangian-Explicit / CIAM (Calcul d'Interface Affine par
Morceaux) method or the Weymouth and Yue (WY) Eulerian-Implicit method. The WY
method conserves fluid mass to machine accuracy provided incompressiblity is
satisfied which leads to a method that is both momentum and mass-conserving. To
improve the stability of these methods momentum fluxes are advected in a manner
"consistent" with the volume-fraction fluxes, that is a discontinuity of the
momentum is advected at the same speed as a discontinuity of the density. To
find the density on the staggered cells on which the velocity is centered, an
auxiliary reconstruction of the density is performed. The method is tested for
a droplet without surface tension in uniform flow, for a droplet suddenly
accelerated in a carrying gas at rest at very large density ratio without
viscosity or surface tension, for the Kelvin-Helmholtz instability, for a
falling raindrop and for an atomizing flow in air-water conditions
Exciton Gas Compression and Metallic Condensation in a Single Semiconductor Quantum Wire
We study the metal-insulator transition in individual self-assembled quantum
wires and report optical evidences of metallic liquid condensation at low
temperatures. Firstly, we observe that the temperature and power dependence of
the single nanowire photoluminescence follow the evolution expected for an
electron-hole liquid in one dimension. Secondly, we find novel spectral
features that suggest that in this situation the expanding liquid condensate
compresses the exciton gas in real space. Finally, we estimate the critical
density and critical temperature of the phase transition diagram at
cm and K, respectively.Comment: 4 pages, 5 figure
La Tasa Turística: una aproximación a su impacto en la Comunidad Valenciana
El trabajo explica las ventajas e inconvenientes de la tasa turística, así como las opiniones de empresarios y profesionales al respecto y alternativas a la recaudación de la tasa
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