9,959 research outputs found
Recursive Copy and Paste GAN: Face Hallucination from Shaded Thumbnails.
Existing face hallucination methods based on convolutional neural networks (CNNs) have achieved impressive performance on low-resolution (LR) faces in a normal illumination condition. However, their performance degrades dramatically when LR faces are captured in non-uniform illumination conditions. This paper proposes a Recursive Copy and Paste Generative Adversarial Network (Re-CPGAN) to recover authentic high-resolution (HR) face images while compensating for non-uniform illumination. To this end, we develop two key components in our Re-CPGAN: internal and recursive external Copy and Paste networks (CPnets). Our internal CPnet exploits facial self-similarity information residing in the input image to enhance facial details; while our recursive external CPnet leverages an external guided face for illumination compensation. Specifically, our recursive external CPnet stacks multiple external Copy and Paste (EX-CP) units in a compact model to learn normal illumination and enhance facial details recursively. By doing so, our method offsets illumination and upsamples facial details progressively in a coarse-to-fine fashion, thus alleviating the ambiguity of correspondences between LR inputs and external guided inputs. Furthermore, a new illumination compensation loss is developed to capture illumination from the external guided face image effectively. Extensive experiments demonstrate that our method achieves authentic HR images in a uniform illumination condition with a 16x magnification factor and outperforms state-of-the-art methods qualitatively and quantitatively
Gene and Pathway-Based Analysis: Second Wave of Genome-wide Association Studies
Despite great success of GWAS in identification of common genetic variants associated with complex diseases, the current GWAS have focused on single SNP analysis. However, single SNP analysis often identifies a number of the most significant SNPs that account for only a small proportion of the genetic variants and offers limited understanding of complex diseases. To overcome these limitations, we propose gene and pathway-based association analysis as a new paradigm for GWAS. As a proof of concept, we performed a comprehensive gene and pathway-based association analysis for thirteen published GWAS. Our results showed that the proposed new paradigm for GWAS not only identified the genes that include significant SNPs found by single SNP analysis, but also detected new genes in which each single SNP conferred small disease risk, but their joint actions were implicated in the development of diseases. The results also demonstrated that the new paradigm for GWAS was able to identify biologically meaningful pathways associated with the diseases which were confirmed by gene-set rich analysis using gene expression data
Self doping effect and successive magnetic transitions in superconducting SrVFeAsO
We have studied a quinary Fe-based superconductor SrVFeAsO by the
measurements of x-ray diffraction, x-ray absorption, M\"{o}ssbauer spectrum,
resistivity, magnetization and specific heat. This apparently undoped
oxyarsenide is shown to be self doped via electron transfer from the V
ions. We observed successive magnetic transitions within the VO layers: an
antiferromagnetic transition at 150 K followed by a weak ferromagnetic
transition at 55 K. The spin orderings within the VO planes are discussed
based on mixed valence of V and V.Comment: One Table and more references are adde
Doping and temperature dependence of electron spectrum and quasiparticle dispersion in doped bilayer cuprates
Within the t-t'-J model, the electron spectrum and quasiparticle dispersion
in doped bilayer cuprates in the normal state are discussed by considering the
bilayer interaction. It is shown that the bilayer interaction splits the
electron spectrum of doped bilayer cuprates into the bonding and antibonding
components around the point. The differentiation between the bonding
and antibonding components is essential, which leads to two main flat bands
around the point below the Fermi energy. In analogy to the doped
single layer cuprates, the lowest energy states in doped bilayer cuprates are
located at the point. Our results also show that the striking
behavior of the electronic structure in doped bilayer cuprates is intriguingly
related to the bilayer interaction together with strong coupling between the
electron quasiparticles and collective magnetic excitations.Comment: 9 pages, 4 figures, updated references, added figures and
discussions, accepted for publication in Phys. Rev.
Peacock Bundles: Bundle Coloring for Graphs with Globality-Locality Trade-off
Bundling of graph edges (node-to-node connections) is a common technique to
enhance visibility of overall trends in the edge structure of a large graph
layout, and a large variety of bundling algorithms have been proposed. However,
with strong bundling, it becomes hard to identify origins and destinations of
individual edges. We propose a solution: we optimize edge coloring to
differentiate bundled edges. We quantify strength of bundling in a flexible
pairwise fashion between edges, and among bundled edges, we quantify how
dissimilar their colors should be by dissimilarity of their origins and
destinations. We solve the resulting nonlinear optimization, which is also
interpretable as a novel dimensionality reduction task. In large graphs the
necessary compromise is whether to differentiate colors sharply between locally
occurring strongly bundled edges ("local bundles"), or also between the weakly
bundled edges occurring globally over the graph ("global bundles"); we allow a
user-set global-local tradeoff. We call the technique "peacock bundles".
Experiments show the coloring clearly enhances comprehensibility of graph
layouts with edge bundling.Comment: Appears in the Proceedings of the 24th International Symposium on
Graph Drawing and Network Visualization (GD 2016
A Flux-Limited Sample of z~1 Ly-alpha Emitting Galaxies in the CDFS
We describe a method for obtaining a flux-limited sample of Ly-alpha emitters
from GALEX grism data. We show that the multiple GALEX grism images can be
converted into a three-dimensional (two spatial axes and one wavelength axis)
data cube. The wavelength slices may then be treated as narrowband images and
searched for emission-line galaxies. For the GALEX NUV grism data, the method
provides a Ly-alpha flux-limited sample over the redshift range z=0.67-1.16. We
test the method on the Chandra Deep Field South field, where we find 28
Ly-alpha emitters with faint continuum magnitudes (NUV>22) that are not present
in the GALEX pipeline sample. We measure the completeness by adding artificial
emitters and measuring the fraction recovered. We find that we have an 80%
completeness above a Ly-alpha flux of 10^-15 erg/cm^2/s. We use the UV spectra
and the available X-ray data and optical spectra to estimate the fraction of
active galactic nuclei in the selection. We report the first detection of a
giant Ly-alpha blob at z<1, though we find that these objects are much less
common at z=1 than at z=3. Finally, we compute limits on the z~1 Ly-alpha
luminosity function and confirm that there is a dramatic evolution in the
luminosity function over the redshift range z=0-1.Comment: 18 pages, in press at The Astrophysical Journa
Role of multiband effects and electron-hole asymmetry in the superconductivity and normal state properties of Ba(FeCo)As
We report a systematic investigation, together with a theoretical analysis,
of the resistivity and Hall effect in single crystals of
Ba(FeCo)As, over a wide doping range. We find a
surprisingly great disparity between the relaxation rates of the holes and the
electrons, in excess of an order of magnitude in the low-doping,
low-temperature regime. The ratio of the electron to hole mobilities diminishes
with temperature and doping (away from the magnetically ordered state) and
becomes more conventional. We also find a straightforward explanation of the
large asymmetry (compared to cuprates) of the superconducting dome: in the
underdoped regime the decisive factor is the competition between AF and
superconductivity (SC), while in the overdoped regime the main role is played
by degradation of the nesting that weakens the pairing interaction. Our results
indicate that spin-fluctuations due to interband electron-hole scattering play
a crucial role not only in the superconducting pairing, but also in the normal
transport.Comment: 4 pages, 4 figure
Computing the lower and upper bounds of Laplace eigenvalue problem: by combining conforming and nonconforming finite element methods
This article is devoted to computing the lower and upper bounds of the
Laplace eigenvalue problem. By using the special nonconforming finite elements,
i.e., enriched Crouzeix-Raviart element and extension , we get
the lower bound of the eigenvalue. Additionally, we also use conforming finite
elements to do the postprocessing to get the upper bound of the eigenvalue. The
postprocessing method need only to solve the corresponding source problems and
a small eigenvalue problem if higher order postprocessing method is
implemented. Thus, we can obtain the lower and upper bounds of the eigenvalues
simultaneously by solving eigenvalue problem only once. Some numerical results
are also presented to validate our theoretical analysis.Comment: 19 pages, 4 figure
A phase-resolved XMM-Newton Campaign on the Colliding Wind Binary HD 152248
We report the first results of an XMM-Newton monitoring campaign of the NGC
6231 open cluster in the Sco OB1 association. This first paper focuses on the
massive colliding wind binary HD 152248, which is the brightest X-ray source of
the cluster. The campaign, with a total duration of 180 ksec, was split into
six separate observations, following the orbital motion of HD 152248. The X-ray
flux from this system presents a clear, asymmetric modulation with the phase
and ranges from 0.73 to 1.18 10-12 erg s-1 cm-2 in the [0.5-10.0 keV] energy
band. The maximum of the emission is reached slightly after apastron. The EPIC
spectra are quite soft and peak around 0.8-0.9 keV. We characterize their shape
using several combinations of mekal models and power-law spectra and we detect
significant spectral variability in the [0.5-2.5 keV] energy band. We also
perform 2-D hydrodynamical simulations using different sets of parameters that
closely reproduce the physical and orbital configuration of the HD 152248
system at the time of the six XMM-Newton pointings. This allows a direct
confrontation of the model predictions with the constraints deduced from the
X-ray observations of the system. We show that the observed variation of the
flux can be explained by a variation of the X-ray emission from the colliding
wind zone, diluted by the softer X-ray contribution of the two O-type stars of
the system. Our simulations also reveal that the interaction region of HD
152248 should be highly unstable, giving rise to shells of dense gas that are
separated by low density regions. Finally, we perform a search for short-term
variability in the light curves of the system and we show that trends are
present within several of the 30 ksec exposures of our campaign. Further, most
of these trends are in good .Comment: Accepted by MNRAS; 22 pages; without figures; complete PS version
(including figures) on http://vela.astro.ulg.ac.be/Preprints/index.htm
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