10,609 research outputs found
Light scattering from self-affine fractal silver surfaces with nanoscale cutoff: Far-field and near-field calculations
We study the light scattered from randomly rough, one-dimensional self-affine
fractal silver surfaces with nanoscale lower cutoff, illuminated by s- or
p-polarized Gaussian beams a few microns wide. By means of rigorous numerical
calculations based on the Green theorem integral equation formulation, we
obtain both the far- and near-field scattered intensities. The influence of
diminishing the fractal lower scale cutoff (from below a hundred, down to a few
nanometers) is analyzed in the case of both single realizations and ensemble
average magnitudes. For s polarization, variations are small in the far field,
being only significant in the higher spatial frequency components of evanescent
character in the near field. In the case of p polarization, however, the
nanoscale cutoff has remarkable effects stemming from the roughness-induced
excitation of surface-plasmon polaritons. In the far field, the effect is
noticed both in the speckle pattern variation and in the decrease of the total
reflected energy upon ensemble averaging, due to increased absorption. In the
near field, more efficient excitation of localized optical modes is achieved
with smaller cutoff, which in turn leads to huge surface electric field
enhancements.Comment: REVTeX 4, 10 page
Numerical simulation of electromagnetic wave scattering from planar dielectric films deposited on rough perfectly conducting substrates
Electromagnetic wave scattering from planar dielectric films deposited on
one-dimensional, randomly rough, perfectly conducting substrates is studied by
numerical simulations for both p- and s-polarization. The reduced Rayleigh
equation, which is the integral equation satisfied by the scattering amplitude
after eliminating the fields inside the film, is the starting point for the
simulation. This equation is solved numerically by considering a random surface
of finite length, and by introducing wave number cut-offs in the evanescent
part of the spectrum. Upon discretization, a system of linear equations is
obtained, and by solving this matrix system for an ensemble of surface
realizations, the contribution to the mean differential reflection coefficient
from the incoherently scattered field, (\nu=p,s), is obtained nonperturbatively. It is demonstrated
that when the scattering geometry supports at least two guided waves,
, has, in addition to the well known
enhanced backscattering peak, well-defined satellite peaks in agreement with
theory, for most of the parameters considered.Comment: 11 pages and 11 figure
Selective Transparence of Single-Mode Waveguides with Surface Scattering
A random surface scattering in a one-mode waveguide is studied in the case
when the surface profile has long-range correlations along the waveguide.
Analytical treatment of this problem shows that with a proper choice of the
surface, one can arrange any desired combination of transparent and
non-transparent frequency windows. We suggest a method to find such profiles,
and demonstrate its effectiveness by making use of direct numerical
simulations.Comment: RevTex, 3 pages including 2 ps-figure
Tourism and hospitality sector electricity use: evidences from 12 EU countries
At the Paris Conference of the Parties (COP21) in 2015, 195 countries agreed to strengthen the global response to the threat of climate change. Along this line, the EU is committed to a 40% reduction in their domestic greenhouse gas emissions by 2030. This new target represents a significant progression beyond its existing 20% emission reduction commitment by 2020. Thus, greater efforts will be needed affecting all productive sectors in order to reduce CO2 emissions and energy consumption.
In order to reach this ambitious target, new measures affecting all economic sectors would be needed. This paper focuses on the tourism sector. This aim of this study is to investigate the relationships between tourist overnight stays and the hospitality sector electricity consumption. These relationships are studied for 12 EU countries during the period 2005-2012, accordingly with the available data. With this aim, econometric panel data techniques are used in order to estimate an electricity consumption function for the hospitality sector which depends on tourism, income, price and climate variables.
The Environmental Kuznets Curve hypothesis is also tested. An Energy-tourism Kuznets Curve would show that increasing earnings from tourism will bring about reduced electricity consumption from a threshold point, which could be related to the fact that more earnings could imply undertaking more energy efficiency measures
Can cognitive performance predict physical fitness and academic achievement one year later?
Previous
studies
have
shown
that
physical
activity,
fitness
and
academic
achievement
might
predict
cognitive
performance
later
in
life
.
However,
to
the
best
of
our
knowledge,
there
are
no
studies
examining
the
inverse
relationship,
that
is,
whether
cognition
may
predict
fitness
and
academic
achievement
in
adolescents
one
year
later
.
Therefore,
the
aim
of
this
study
was
to
examine
the
associations
between
cognitive
performance
and
physical
fitness
and
academic
achievement
one
year
later
.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Reproductive biology of "Helianthemum apennium" (L.) Mill. and "H. caput-felis" Boiss. (Cistaceae) from Mallorca (Balearic Island, Spain)
El estudio de la biología reproductiva de poblaciones naturales de Helianthemum apenninum y H. caput-felis en Mallorca ha demostrado que son básicamente entomófilos, aunque también producen numerosos frutos por auto-polinización. Las flores de H. caput-felis duran cuatro dias, mientras que las de H.apenninum duran uno, como suele ocurrir en otras especies del género. En la población de H. apenninum, la predación por ungulados afecta al 50% de los individuos. Los test de germinación mostraron una temperatura óptima de germinación de 16 ºC para H. apenninum y de 23ºC para H. caput-felis. H. caput-felis muestra una importante variabilidad interanual en su comportamiento germinativo. En las poblaciones naturales de H. caput-felis, se ha observado atelecoria, y en relación con ésta, las semillas germinan dentro de la cápsula
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