2,260 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
Lithium abundance evolution in open clusters: Hyades, NGC752, and M67
Mixing mechanisms bring the Li from the base of the convective zone to deeper
and warmer layers where it is destroyed. These mechanisms are investigated by
comparing observations of Li abundances in stellar atmospheres to models of
stellar evolution. Observations in open cluster are especially suitable for
this comparison, since their age and metallicity are homogeneous among their
members and better determined than in field stars. In this work, we compare the
evolution of Li abundances in three different clusters: the Hyades, NGC752, and
M67. Our models are calculated with microscopic diffusion and transport of
chemicals by meridional circulation, and calibrated on the Sun. These
comparisons allow us to follow the evolution of Li abundance as a function of
stellar mass in each cluster and as a function of the age by comparing this
evolution in each cluster. We evaluate the efficiency of the mixing mechanisms
used in the models, and we try to identify the lacking mechanisms to reproduce
the observed evolution of Li abundance.Comment: 6 pages, 4 figures, conference publication of "New advances in
stellar physics: from microscopic to macroscopic processes
Power-law statistics and stellar rotational velocities in the Pleiades
In this paper we will show that, the non-gaussian statistics framework based
on the Kaniadakis statistics is more appropriate to fit the observed
distributions of projected rotational velocity measurements of stars in the
Pleiades open cluster. To this end, we compare the results from the
and -distributions with the Maxwellian.Comment: 13 pages, 3 figure
Complexity-Aware Assignment of Latent Values in Discriminative Models for Accurate Gesture Recognition
Many of the state-of-the-art algorithms for gesture recognition are based on
Conditional Random Fields (CRFs). Successful approaches, such as the
Latent-Dynamic CRFs, extend the CRF by incorporating latent variables, whose
values are mapped to the values of the labels. In this paper we propose a novel
methodology to set the latent values according to the gesture complexity. We
use an heuristic that iterates through the samples associated with each label
value, stimating their complexity. We then use it to assign the latent values
to the label values. We evaluate our method on the task of recognizing human
gestures from video streams. The experiments were performed in binary datasets,
generated by grouping different labels. Our results demonstrate that our
approach outperforms the arbitrary one in many cases, increasing the accuracy
by up to 10%.Comment: Conference paper published at 2016 29th SIBGRAPI, Conference on
Graphics, Patterns and Images (SIBGRAPI). 8 pages, 7 figure
Effects of reversible inactivation of the dorsomedial hypothalamus on panic- and anxiety-related responses in rats
The medial hypothalamus is part of a neurobiological substrate controlling defensive behavior. It has been shown that a hypothalamic nucleus, the dorsomedial hypothalamus (DMH), is involved in the regulation of escape, a defensive behavior related to panic attacks. The role played by the DMH in the organization of conditioned fear responses, however, is less clear. In the present study, we investigated the effects of reversible inactivation of the DMH with the GABA A agonist muscimol on inhibitory avoidance acquisition and escape expression by male Wistar rats (approximately 280 g in weight) tested in the elevated T-maze (ETM). In the ETM, inhibitory avoidance, a conditioned defensive response, has been associated with generalized anxiety disorder. Results showed that intra-DMH administration of the GABA A receptor agonist muscimol inhibited escape performance, suggesting an antipanic-like effect (P < 0.05), without changing inhibitory avoidance acquisition. Although a higher dose of muscimol (1.0 nmol/0.2 µL; N = 7) also altered locomotor activity in an open field when compared to control animals (0.2 µL saline; N = 13) (P < 0.05), the lower dose (0.5 nmol/0.2 µL; N = 12) of muscimol did not cause any motor impairment. These data corroborate previous evidence suggesting that the DMH is specifically involved in the modulation of escape. Dysfunction of this regulatory mechanism may be relevant in the genesis/maintenance of panic disorder
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