13,045 research outputs found
ICLabel: An automated electroencephalographic independent component classifier, dataset, and website
The electroencephalogram (EEG) provides a non-invasive, minimally
restrictive, and relatively low cost measure of mesoscale brain dynamics with
high temporal resolution. Although signals recorded in parallel by multiple,
near-adjacent EEG scalp electrode channels are highly-correlated and combine
signals from many different sources, biological and non-biological, independent
component analysis (ICA) has been shown to isolate the various source generator
processes underlying those recordings. Independent components (IC) found by ICA
decomposition can be manually inspected, selected, and interpreted, but doing
so requires both time and practice as ICs have no particular order or intrinsic
interpretations and therefore require further study of their properties.
Alternatively, sufficiently-accurate automated IC classifiers can be used to
classify ICs into broad source categories, speeding the analysis of EEG studies
with many subjects and enabling the use of ICA decomposition in near-real-time
applications. While many such classifiers have been proposed recently, this
work presents the ICLabel project comprised of (1) an IC dataset containing
spatiotemporal measures for over 200,000 ICs from more than 6,000 EEG
recordings, (2) a website for collecting crowdsourced IC labels and educating
EEG researchers and practitioners about IC interpretation, and (3) the
automated ICLabel classifier. The classifier improves upon existing methods in
two ways: by improving the accuracy of the computed label estimates and by
enhancing its computational efficiency. The ICLabel classifier outperforms or
performs comparably to the previous best publicly available method for all
measured IC categories while computing those labels ten times faster than that
classifier as shown in a rigorous comparison against all other publicly
available EEG IC classifiers.Comment: Intended for NeuroImage. Updated from version one with minor
editorial and figure change
Imaging and Demography of the Host Galaxies of High-Redshift Type Ia Supernovae
We present the results of a study of the host galaxies of high redshift Type
Ia supernovae (SNe Ia). We provide a catalog of 18 hosts of SNe Ia observed
with the Hubble Space Telescope (HST) by the High-z Supernova Search Team
(HZT), including images, scale-lengths, measurements of integrated (Hubble
equivalent) BVRIZ photometry in bands where the galaxies are brighter than m ~
25 mag, and galactocentric distances of the supernovae. We compare the
residuals of SN Ia distance measurements from cosmological fits to measurable
properties of the supernova host galaxies that might be expected to correlate
with variable properties of the progenitor population, such as host galaxy
color and position of the supernova. We find mostly null results; the current
data are generally consistent with no correlations of the distance residuals
with host galaxy properties in the redshift range 0.42 < z < 1.06. Although a
subsample of SN hosts shows a formally significant (3-sigma) correlation
between apparent V-R host color and distance residuals, the correlation is not
consistent with the null results from other host colors probed by our largest
samples. There is also evidence for the same correlations between SN Ia
properties and host type at low redshift and high redshift. These similarities
support the current practice of extrapolating properties of the nearby
population to high redshifts pending more robust detections of any correlations
between distance residuals from cosmological fits and host properties.Comment: 35 pages, 12 figures, 4 tables, accepted for publication in A
Deep Learning and Music Adversaries
OA Monitor ExerciseOA Monitor ExerciseAn {\em adversary} is essentially an algorithm intent on making a classification system perform in some particular way given an input, e.g., increase the probability of a false negative. Recent work builds adversaries for deep learning systems applied to image object recognition, which exploits the parameters of the system to find the minimal perturbation of the input image such that the network misclassifies it with high confidence. We adapt this approach to construct and deploy an adversary of deep learning systems applied to music content analysis. In our case, however, the input to the systems is magnitude spectral frames, which requires special care in order to produce valid input audio signals from network-derived perturbations. For two different train-test partitionings of two benchmark datasets, and two different deep architectures, we find that this adversary is very effective in defeating the resulting systems. We find the convolutional networks are more robust, however, compared with systems based on a majority vote over individually classified audio frames. Furthermore, we integrate the adversary into the training of new deep systems, but do not find that this improves their resilience against the same adversary
LANDSAT-D investigations in snow hydrology
Work undertaken during the contract and its results are described. Many of the results from this investigation are available in journal or conference proceedings literature - published, accepted for publication, or submitted for publication. For these the reference and the abstract are given. Those results that have not yet been submitted separately for publication are described in detail. Accomplishments during the contract period are summarized as follows: (1) analysis of the snow reflectance characteristics of the LANDSAT Thematic Mapper, including spectral suitability, dynamic range, and spectral resolution; (2) development of a variety of atmospheric models for use with LANDSAT Thematic Mapper data. These include a simple but fast two-stream approximation for inhomogeneous atmospheres over irregular surfaces, and a doubling model for calculation of the angular distribution of spectral radiance at any level in an plane-parallel atmosphere; (3) incorporation of digital elevation data into the atmospheric models and into the analysis of the satellite data; and (4) textural analysis of the spatial distribution of snow cover
A uvbyCaHbeta Analysis of the Old Open Cluster, NGC 6819
NGC 6819 is a richly populated, older open cluster situated within the Kepler
field. A CCD survey of the cluster on the uvbyCaHbeta system, coupled with
proper-motion membership, has been used to isolate 382 highly probable,
single-star unevolved main-sequence members over a 20-arcminute field centered
on the cluster. From 278 F dwarfs with high precision photometry in all
indices, a mean reddening of E(b-y) = 0.117 +/- 0.005 or E(B-V) = 0.160 +/-
0.007 is derived, where the standard errors of the mean include both internal
errors and the photometric zero-point uncertainty. With the reddening fixed,
the metallicity derived from the same 278 stars is [Fe/H] = -0.116 +/- 0.101
from m_1 and -0.055 +/- 0.033 from hk, for a weighted average of [Fe/H] = -0.06
+/- 0.04, where the quoted standard errors of the mean values include the
internal errors from the photometric scatter plus the uncertainty in the
photometric zero points. If metallicity is derived using individual reddening
values for each star to account for potential reddening variation across the
face of the cluster, the analogous result is unchanged. The cluster members at
the turnoff of the color-magnitude diagram are used to test and confirm the
recently discovered variation in reddening across the face of the cluster, with
a probable range in the variation of Delta[E(B-V)] = 0.045 +/-0.015. With the
slightly higher reddening and lower [Fe/H] compared to commonly adopted values,
isochrone fitting leads to an age of 2.3 +/- 0.2 Gyr for an apparent modulus of
(m-M) = 12.40 +/-0.12.Comment: WIYN Open Cluster Study LXI; accepted to Astronomical Journal. 11
figures, 2 table
EVOLUTION OF IR-SELECTED GALAXIES IN Z~0.4 CLUSTERS
Wide-field optical and near--IR () imaging is presented for two rich
galaxy clusters: Abell~370 at and Abell~851 (Cl0939+47) at .
Galaxy catalogs selected from the near--IR images are 90\% complete to
approximately 1.5 mag below resulting in samples with 100
probable member galaxies per cluster in the central 2 Mpc. Comparison
with WFPC images yields subsamples of 70 galaxies in each cluster
with morphological types. Analysis of the complete samples and the
subsamples shows that the E/S0s are bluer than those in the Bower
et al.\ (1992) Coma sample in the optical color by ~mag for Abell~370
and by ~mag for Abell~851. If real, the bluing of the E/S0 populations at
moderate redshift is consistent with that calculated from the Bruzual and
Charlot (1993) models of passive elliptical galaxy evolution. In both clusters
the intrinsic scatter of the known E/S0s about their optical color--mag
relation is small ( mag) and not significantly different from that
of Coma E/S0s as given by Bower et al.\ (1992), indicating that the galaxies
within each cluster formed at the same time at an early epoch.Comment: uuencoded gzipped tar file containing latex files of manuscript (42
pages) plus tables (9 pages); figures available by anonymous ftp at
ftp://ipac.caltech.edu//pub/pickup/sed ; accepted for publication in the Ap
Grouping Normal Type Ia Supernovae by UV to Optical Color Differences
Observations of many SNe Ia with the UVOT instrument on the Swift satellite
has revealed that there exists order to the differences in the UV-OPT colors of
normal SNe. We examine UV-OPT color curves for 25 SNe Ia, dividing them into 4
groups, finding that ~1/3 of these SNe Ia have bluer UV-OPT colors than the
larger group, with these "NUV-blue" SNe Ia 0.4 mag bluer than the "NUV-red" SNe
Ia in u-v. Another group of events feature colors similar to NUV-red SNe Ia in
the u-v to uvw1-v colors, but similar to the NUV-blue SNe Ia in the uvm2-v
color. We name these events "MUV-blue". The last group initially has colors
similar to NUV-red SNe Ia, but with color curves that feature more modest
changes than the larger NUV-red group. These "irregular" events are comprised
of all the NUV-red events with the broadest optical peaks, which leads us to
consider this minor group a subset of the NUV-red group. When so separated and
the accounting is made for the rapid time evolution of the UV-OPT colors, we
find that the scatter in two NUV-OPT colors, u-v & uvw1-v, is at the level of
the scatter in b-v. This finding is promising for extending the cosmological
utilization of SNe Ia into the NUV. We generate spectrophotometry of SNe Ia
that have been observed with HST and argue that there is a fundamental spectral
difference in the 2900-3500A wavelength range, a range suggested to be
dominated by absorption from iron-peak elements. The NUV-blue SNe Ia feature
less NUV absorption than the NUV-red SNe Ia. We show that all the NUV-blue SNe
Ia in this sample have also featured evidence of unburned carbon in optical
spectra, whereas only one NUV-red SN Ia features that absorption line. Every
NUV-blue event also exhibits a low gradient of the SiII 6355A absorption
feature, but many NUV-red events also exhibit a low gradient, perhaps
suggestive that NUV-blue events are a subset of the larger LVG group.Comment: Accepted to the Astrophysical Journal Updated version: Sept 16, 201
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