38,453 research outputs found
Microlensing path parametrization for Earth-like Exoplanet detection around solar mass stars
We propose a new parametrization of the impact parameter u0 and impact angle
{\alpha} for microlensing systems composed by an Earth-like Exoplanet around a
Solar mass Star at 1 AU. We present the caustic topology of such system, as
well as the related light curves generated by using such a new parametrization.
Based on the same density of points and accuracy of regular methods, we obtain
results 5 times faster for discovering Earth-like exoplanet. In this big data
revolution of photometric astronomy, our method will impact future missions
like WFIRST (NASA) and Euclid (ESA) and they data pipelines, providing a rapid
and deep detection of exoplanets for this specific class of microlensing event
that might otherwise be lost.Comment: 8 pages, 7 figures, accepted to be published in The Astronomical
Journa
Self-dual Hopfions
We construct static and time-dependent exact soliton solutions with
non-trivial Hopf topological charge for a field theory in 3+1 dimensions with
the target space being the two dimensional sphere S**2. The model considered is
a reduction of the so-called extended Skyrme-Faddeev theory by the removal of
the quadratic term in derivatives of the fields. The solutions are constructed
using an ansatz based on the conformal and target space symmetries. The
solutions are said self-dual because they solve first order differential
equations which together with some conditions on the coupling constants, imply
the second order equations of motion. The solutions belong to a sub-sector of
the theory with an infinite number of local conserved currents. The equation
for the profile function of the ansatz corresponds to the Bogomolny equation
for the sine-Gordon model.Comment: plain latex, no figures, 23 page
Plasma Processing of Large Curved Surfaces for SRF Cavity Modification
Plasma based surface modification of niobium is a promising alternative to
wet etching of superconducting radio frequency (SRF) cavities. The development
of the technology based on Cl2/Ar plasma etching has to address several crucial
parameters which influence the etching rate and surface roughness, and
eventually, determine cavity performance. This includes dependence of the
process on the frequency of the RF generator, gas pressure, power level, the
driven (inner) electrode configuration, and the chlorine concentration in the
gas mixture during plasma processing. To demonstrate surface layer removal in
the asymmetric non-planar geometry, we are using a simple cylindrical cavity
with 8 ports symmetrically distributed over the cylinder. The ports are used
for diagnosing the plasma parameters and as holders for the samples to be
etched. The etching rate is highly correlated with the shape of the inner
electrode, radio-frequency (RF) circuit elements, chlorine concentration in the
Cl2/Ar gas mixtures, residence time of reactive species and temperature of the
cavity. Using cylindrical electrodes with variable radius, large-surface
ring-shaped samples and d.c. bias implementation in the external circuit we
have demonstrated substantial average etching rates and outlined the
possibility to optimize plasma properties with respect to maximum surface
processing effect
Comunicação de organizações públicas no twitter.
Globalização e tecnologias digitais de comunicação. Redes sociais: a cultura como pano de fundo. Redes sociais: sobre o twitter. Relacionamento simétrico ou assimétrico das organizações.COMUNICON
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