1,977 research outputs found
RED: Deep Recurrent Neural Networks for Sleep EEG Event Detection
The brain electrical activity presents several short events during sleep that
can be observed as distinctive micro-structures in the electroencephalogram
(EEG), such as sleep spindles and K-complexes. These events have been
associated with biological processes and neurological disorders, making them a
research topic in sleep medicine. However, manual detection limits their study
because it is time-consuming and affected by significant inter-expert
variability, motivating automatic approaches. We propose a deep learning
approach based on convolutional and recurrent neural networks for sleep EEG
event detection called Recurrent Event Detector (RED). RED uses one of two
input representations: a) the time-domain EEG signal, or b) a complex
spectrogram of the signal obtained with the Continuous Wavelet Transform (CWT).
Unlike previous approaches, a fixed time window is avoided and temporal context
is integrated to better emulate the visual criteria of experts. When evaluated
on the MASS dataset, our detectors outperform the state of the art in both
sleep spindle and K-complex detection with a mean F1-score of at least 80.9%
and 82.6%, respectively. Although the CWT-domain model obtained a similar
performance than its time-domain counterpart, the former allows in principle a
more interpretable input representation due to the use of a spectrogram. The
proposed approach is event-agnostic and can be used directly to detect other
types of sleep events.Comment: 8 pages, 5 figures. In proceedings of the 2020 International Joint
Conference on Neural Networks (IJCNN 2020
Classical Lie symmetries and reductions of a nonisospectral Lax pair
The classical Lie method is applied to a nonisospectral problem associated
with a system of partial differential equations in 2+1 dimensions (Maccari A,
J. Math. Phys. 39, (1998), 6547-6551). Identification of the classical Lie
symmetries provides a set of reductions that give rise to different nontrivial
spectral problems in 1+1 dimensions. The form in which the spectral parameter
of the 1+1 Lax pair is introduced is carefully described.Comment: 11 pages (v2: A typo corrected in the authors' names
Estratigrafía y paleografia de las unidades alóctonas del Castell de Bac Grillera (Pirineo oriental, España)
En la presente nota se hace el estudio estratigráfico delenclave alóctono situado al E de Massanet de Cabrenys (Gerona).Estas unidades alóctonas, cuya mayor elevación corresponde al pico del Castell de Bac Grillera (1059 m.), reposan sobre los términos basales del Paleoceno como resultado final de una traslación gravitatoria procedente del NE. Las formaciones estudiadas son de aguas someras y presentan frecuentes cambios laterales de facies.Sobre el mecanismo de traslación y los rasgos estructurales aparecerá un nuevo artículo próximamente
Tectónica de las unidades alóctonas del Castell de Bac Grillera (Pirineo oriental, España)
Como previamente se anunció en anterior publicación sobreestas unidades alóctonas, en esta otra nota se completa el estudio de las mismas al referir los rasgos estructurales observados y el mecanismo de traslación que las originó. Esta traslación, de tipo gravitatorio, se efectuó sobre una superficie de erosión preexistente a partir del NE y se inició, al parecer, a principios del Biarritzense
Period Estimation in Astronomical Time Series Using Slotted Correntropy
In this letter, we propose a method for period estimation in light curves
from periodic variable stars using correntropy. Light curves are astronomical
time series of stellar brightness over time, and are characterized as being
noisy and unevenly sampled. We propose to use slotted time lags in order to
estimate correntropy directly from irregularly sampled time series. A new
information theoretic metric is proposed for discriminating among the peaks of
the correntropy spectral density. The slotted correntropy method outperformed
slotted correlation, string length, VarTools (Lomb-Scargle periodogram and
Analysis of Variance), and SigSpec applications on a set of light curves drawn
from the MACHO survey
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