Text Localization in Video Using Multiscale Weber's Local Descriptor

In this paper, we propose a novel approach for detecting the text present in videos and scene images based on the Multiscale Weber's Local Descriptor (MWLD). Given an input video, the shots are identified and the key frames are extracted based on their spatio-temporal relationship. From each key frame, we detect the local region information using WLD with different radius and neighborhood relationship of pixel values and hence obtained intensity enhanced key frames at multiple scales. These multiscale WLD key frames are merged together and then the horizontal gradients are computed using morphological operations. The obtained results are then binarized and the false positives are eliminated based on geometrical properties. Finally, we employ connected component analysis and morphological dilation operation to determine the text regions that aids in text localization. The experimental results obtained on publicly available standard Hua, Horizontal-1 and Horizontal-2 video dataset illustrate that the proposed method can accurately detect and localize texts of various sizes, fonts and colors in videos.Comment: IEEE SPICES, 201

Center to limb observations and modeling of the Ca I 4227 A line

The observed center-to-limb variation (CLV) of the scattering polarization in different lines of the Second Solar Spectrum can be used to constrain the height variation of various atmospheric parameters, in particular the magnetic fields via the Hanle effect. Here we attempt to model non-magnetic CLV observations of the $Q/I$ profiles of the Ca I 4227 A line recorded with the ZIMPOL-3 at IRSOL. For modeling, we use the polarized radiative transfer with partial frequency redistribution with a number of realistic 1-D model atmospheres. We find that all the standard FAL model atmospheres, used by us, fail to simultaneously fit the observed ($I$, $Q/I$) at all the limb distances ($\mu$). However, an attempt is made to find a single model which can provide a fit at least to the CLV of the observed $Q/I$ instead of a simultaneous fit to the ($I$, $Q/I$) at all $\mu$. To this end we construct a new 1-D model by combining two of the standard models after modifying their temperature structures in the appropriate height ranges. This new combined model closely reproduces the observed $Q/I$ at all the $\mu$, but fails to reproduce the observed rest intensity at different $\mu$. Hence we find that no single 1-D model atmosphere succeeds in providing a good representation of the real Sun. This failure of 1-D models does not however cause an impediment to the magnetic field diagnostic potential of the Ca I 4227 A line. To demonstrate this we deduce the field strength at various $\mu$ positions without invoking the use of radiative transfer.Comment: 20 pages, 10 figures, Accepted for publication in Ap

Quenching across quantum critical points in periodic systems: dependence of scaling laws on periodicity

We study the quenching dynamics of a many-body system in one dimension described by a Hamiltonian that has spatial periodicity. Specifically, we consider a spin-1/2 chain with equal xx and yy couplings and subject to a periodically varying magnetic field in the z direction or, equivalently, a tight-binding model of spinless fermions with a periodic local chemical potential, having period 2q, where q is a natural number. For a linear quench of the magnetic field strength (or potential strength) at rate 1/\tau across a quantum critical point, we find that the density of defects thereby produced scales as 1/\tau^{q/(q+1)}, deviating from the 1/\sqrt{\tau} scaling that is ubiquitous to a range of systems. We analyze this behavior by mapping the low-energy physics of the system to a set of fermionic two-level systems labeled by the lattice momentum k undergoing a non-linear quench as well as by performing numerical simulations. We also find that if the magnetic field is a superposition of different periods, the power law depends only on the smallest period for very large values of \tau although it may exhibit a cross-over at intermediate values of \tau. Finally, for the case where a zz coupling is also present in the spin chain, or equivalently, where interactions are present in the fermionic system, we argue that the power associated with the scaling law depends on a combination of q and interaction strength.Comment: 13 pages including 11 figure

Localization in disordered superconducting wires with broken spin-rotation symmetry

Localization and delocalization of non-interacting quasiparticle states in a superconducting wire are reconsidered, for the cases in which spin-rotation symmetry is absent, and time-reversal symmetry is either broken or unbroken; these are referred to as symmetry classes BD and DIII, respectively. We show that, if a continuum limit is taken to obtain a Fokker-Planck (FP) equation for the transfer matrix, as in some previous work, then when there are more than two scattering channels, all terms that break a certain symmetry are lost. It was already known that the resulting FP equation exhibits critical behavior. The additional symmetry is not required by the definition of the symmetry classes; terms that break it arise from non-Gaussian probability distributions, and may be kept in a generalized FP equation. We show that they lead to localization in a long wire. When the wire has more than two scattering channels, these terms are irrelevant at the short distance (diffusive or ballistic) fixed point, but as they are relevant at the long-distance critical fixed point, they are termed dangerously irrelevant. We confirm the results in a supersymmetry approach for class BD, where the additional terms correspond to jumps between the two components of the sigma model target space. We consider the effect of random $\pi$ fluxes, which prevent the system localizing. We show that in one dimension the transitions in these two symmetry classes, and also those in the three chiral symmetry classes, all lie in the same universality class

Andreev current in finite sized carbon nanotubes

We investigate the effect of interactions on Andreev current at a normal-superconducting junction when the normal phase is a Luttinger liquid with repulsive interactions. In particular, we study the system of a finite sized carbon nanotube placed between one metallic and one superconducting lead. We show that interactions and finite size effects give rise to significant deviations from the standard picture of Andreev current at a normal- superconductor junction in the nearly perfect Andreev limit.Comment: 4 pages, 2 figure

Safety and Efficacy of Hydroxychloroquine in COVID-19: A Systematic Review and Meta-Analysis

Background: During the initial phases of the coronavirus disease 2019 (COVID-19) epidemic, there was an unfounded fervor surrounding the use of hydroxychloroquine (HCQ); however, recently, the Centers for Disease Control and Prevention (CDC) has recommended against routine use of HCQ outside of study protocols citing possible adverse outcomes. Methods: Multiple databases were searched to identify articles on COVID-19. An unadjusted odds ratio (OR) was used to calculate the safety and efficacy of HCQ on a random effect model. Results: Twelve studies comprising 3,912 patients (HCQ 2,512 and control 1400) were included. The odds of all-cause mortality (OR: 2.23, 95% confidence interval (CI): 1.58 - 3.13, P value \u3c 0.00001) were significantly higher in patients on HCQ compared to patients on control agent. The response to therapy assessed by negative repeat polymerase chain reaction (PCR) (OR: 1.83, 95% CI: 0.50 - 6.75, P = 0.36), radiological resolution (OR: 1.98, 95% CI: 0.47 - 8.36, P value = 0.36) and the need for invasive mechanical ventilation (IMV) (OR: 1.21, 95% CI: 0.34 - 4.33, P value = 0.76) were identical between the two groups. Overall, four times higher odds of net adverse events (NAEs) were observed in the HCQ group (OR: 4.59, 95% CI 1.73 - 12.20, P value = 0.02). The measures for individual safety endpoints were also numerically lower in the control arm; however, none of these values reached the level of statistical significance. Conclusions: HCQ might offer no benefits in terms of decreasing the viral load and radiological improvement in patients with COVID-19. HCQ appears to be associated with higher odds of all-cause mortality and NAEs

The InfraRed Imaging Spectrograph (IRIS) for TMT: latest science cases and simulations

The Thirty Meter Telescope (TMT) first light instrument IRIS (Infrared Imaging Spectrograph) will complete its preliminary design phase in 2016. The IRIS instrument design includes a near-infrared (0.85 - 2.4 micron) integral field spectrograph (IFS) and imager that are able to conduct simultaneous diffraction-limited observations behind the advanced adaptive optics system NFIRAOS. The IRIS science cases have continued to be developed and new science studies have been investigated to aid in technical performance and design requirements. In this development phase, the IRIS science team has paid particular attention to the selection of filters, gratings, sensitivities of the entire system, and science cases that will benefit from the parallel mode of the IFS and imaging camera. We present new science cases for IRIS using the latest end-to-end data simulator on the following topics: Solar System bodies, the Galactic center, active galactic nuclei (AGN), and distant gravitationally-lensed galaxies. We then briefly discuss the necessity of an advanced data management system and data reduction pipeline.Comment: 15 pages, 7 figures, SPIE (2016) 9909-0