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Meson screening masses in (2+1)-flavor QCD
No full textWe present lattice QCD results for mesonic screening masses in the temperature range 140 MeV less than or similar to T less than or similar to 2500 MeV. Our calculations were carried out using (2 + 1) flavors of the highly improved staggered quark action, with a physical value for the strange quark mass and two values of the light quark mass corresponding to pion masses of 160 and 140 MeV. Continuum-extrapolated results were obtained using calculations with a variety of lattice spacings corresponding to temporal lattice extents N-tau = 6-16. We discuss the implications of these results for the effective restoration of various symmetries in the high temperature phase of QCD, as well as the approach toward the perturbative limit
UVIT Open Cluster Study. II. Detection of Extremely Low Mass White Dwarfs and Post?Mass Transfer Binaries in M67
No full textA detailed study of the UV-bright stars in the old open star cluster M67 is presented based on the far-UV observations using the Ultra Violet Imaging Telescope (UVIT) on ASTROSAT. The UV and UV?optical color?magnitude diagrams (CMDs), along with overlaid isochrones, are presented for the member stars, which include blue straggler stars (BSSs), triple systems, white dwarfs (WDs), and spectroscopic binaries. The CMDs suggest the presence of excess UV flux in many members, which could be extrinsic or intrinsic to them. We construct multiwavelength spectral energy distributions (SEDs) using photometric data from the UVIT, Gaia DR2, Two Micron All Sky Survey, and Wide-Field Infrared Survey Explorer surveys, along with optical photometry. We fitted model SEDs to seven WDs and find that four of them have mass >0.5 M and cooling age of less than 200 Myr, thus demanding BSS progenitors. SED fits to 23 stars detect extremely low mass (ELM) WD companions to WOCS2007, WOCS6006, and WOCS2002 and a low-mass WD to WOCS3001, which suggest these to be post?mass transfer (MT) systems. Twelve sources with possible WD companions need further confirmation. Nine sources have X-ray and excess UV flux, possibly arising out of stellar activity. This study demonstrates that UV observations are key to detecting and characterizing the ELM WDs in nondegenerate systems, which are ideal test beds to explore the formation pathways of these peculiar WDs. The increasing detection of post-MT systems among BSSs and main-sequence stars suggests a strong MT pathway and stellar interactions in M67
SN 2017gmr: An Energetic Type II-P Supernova with Asymmetries
No full textWe present high-cadence UV, optical, and near-infrared data on the luminous Type II-P supernova SN;2017gmr from hours after discovery through the first 180 days. SN;2017gmr does not show signs of narrow, high-ionization emission lines in the early optical spectra, yet the optical light-curve evolution suggests that an extra energy source from circumstellar medium (CSM) interaction must be present for at least 2 days after explosion. Modeling of the early light curve indicates a ?500 R progenitor radius, consistent with a rather compact red supergiant, and late-time luminosities indicate that up to 0.130;;0.026 M of Ni-56 are present, if the light curve is solely powered by radioactive decay, although the Ni-56 mass may be lower if CSM interaction contributes to the post-plateau luminosity. Prominent multipeaked emission lines of H? and O i] emerge after day 154, as a result of either an asymmetric explosion or asymmetries in the CSM. The lack of narrow lines within the first 2 days of explosion in the likely presence of CSM interaction may be an example of close, dense, asymmetric CSM that is quickly enveloped by the spherical supernova ejecta
Axial Super-Resolution in Ultrasound Imaging
No full textA fundamental challenge in non-destructive evaluation using ultrasound is to accurately estimate the thicknesses of different layers or cracks present in the object being probed. This inherently corresponds to localizing the point-sources of the reflections from the received signal. Conventional signal processing techniques cannot resolve reflectors whose spacing is below the axial resolution limit, which is of the order of the wavelength of the probing pulse. The objective of this paper is to demonstrate axial super-resolution capability using both simulated and experimental ultrasound data. We show that the ultrasound reflections could be modelled effectively as FRI signals, which can be sampled at sub-Nyquist rates. The FRI sampling method brings the reconstruction problem within a parametric estimation framework, for which efficient high-resolution spectral estimation techniques are available. We experimentally demonstrate that the proposed technique is able to resolve the thicknesses of layers of custom designed Agarose phantoms that are up to 2.25 times below the conventional resolution limit
Synthesis and electrical properties of lead-free piezo electrics for magnetoelectric applications
No full textThe Lead-free piezoelectric polycrystalline materials, BaTiO3 (BTO) and Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramic are prepared by sol-gel synthesis method. The synthesis dynamics and the effect of sintering temperature on the purity and the formation of morphotropic phase boundaries in these samples are investigated. X-ray Diffraction studies show the cubic phase for the BTO at low temperature, whereas it transforms into the tetragonal for higherature synthesis. The BCZT exists in the mixed phases of tetragonal and orthorhombic structures. Formation of MPBs in BCZT are observed for the sintering temperature above 1350 °C. Polarization (P) versus electric field (E) measurement shows enhanced polarization values for the BCZT in comparison to the BTO
Sequential Random Distortion Testing of Non-Stationary Processes
No full textIn this work, we propose a non-parametric sequential hypothesis test based on random distortion testing (RDT). RDT addresses the problem of testing whether or not a random signal, Ξ, observed in independent and identically distributed (i.i.d) additive noise deviates by more than a specified tolerance, τ, from a fixed model, ξ 0. The test is non-parametric in the sense that the underlying signal distributions under each hypothesis are assumed to be unknown. The need to control the probabilities of false alarm (PFA) and missed detection (PMD), while reducing the number of samples required to make a decision, leads to a novel sequential algorithm, SeqRDT. We show that under mild assumptions on the signal, SeqRDT follows the properties desired by a sequential test. We introduce the concept of a buffer and derive bounds on PFA and PMD, from which we choose the buffer size. Simulations show that SeqRDT leads to faster decision-making on an average compared to its fixed-sample-size (FSS) counterpart, BlockRDT. These simulations also show that the proposed algorithm is robust to model mismatches compared to the sequential probability ratio test (SPRT)
A Novel Application of Multiscale Low-Rank Image Decomposition for Optic Disc Localization
No full textWe propose optic disc localization using a multiscale low-rank image decomposition technique, which separates the optic disc from other features on the retina. By decomposing the input image as the sum of L images, each at a specific scale and minimizing the rank of these blocks to emphasize the details at that scale. At one of the scales, the optic disc is isolated. Thereafter, we employ blob detection algorithms to localize the optic disc. The proposed method has been tested on seven fundus image databases amounting to a total of 2035 images, achieving an accuracy of 100, 100, 96.15, 97.75, 98.15, 96.85 and 96.41 on DRIVE, DRIONS-DB, DIARETDBO, DIARETDB1, IDRiD-1, IDRiD-2, and MESSIDOR databases, respectively. Synthetically generated images with features at different scales were used to test the rate of convergence of the method as well
Microstructured Ceramic-Coated Carbon Nanotube Surfaces for High Heat Flux Pool Boiling
No full textStable surfaces with high boiling heat flux are critical to many thermal and energy conversion systems, and it is well-known that the microscale texture and wettability of a surface influences its critical heat flux (CHF). We investigate pool boiling on microstructured ceramic-coated carbon nanotube (CNT) surfaces. CNT microstructures are patterned with precise dimensions over large areas, and a ceramic coating by atomic layer deposition (ALD) imparts stability in the presence of capillary forces and thermal stresses that occur during boiling, achieving a measured CHF as high as 245 W cm-2. We also show that the nanoporosity of the ceramic-CNT microstructures has a negligible influence on the CHF because surface rewetting is dominated by microscale imbibition. The high CHF values achieved on our surfaces are attributed to the micropatterning and the nanoscale surface texture of the CNTs, which accelerate liquid imbibition upon bubble departure. Our findings also suggest further enhancements in CHF can be made by optimizing the microstructure pattern and improving its wettability. Therefore, micropatterned ceramic-CNT composites are a potentially attractive substrate for industrial applications of pool boiling
Service resilience framework for enhanced end-to-end service quality
No full textA major risk that cloud computing paradigm encounters in enabling computing as a utility is service disruption. With component failures, performance interferences, load dynamics, etc., increasing with scale, it is challenging to meet user expectations concerning the delivery of cloud services. Prevalent cloud solutions deal with service disruptions as application design choices and mostly adopt to redundant or replicated service instances. This black box approach makes the choice expensive and obviates interesting and smarter choices while dealing with disruptions. More so, as clouds are subjected to dynamic variations in workload, resources and disruptions. This paper details disruption scenarios where autonomous service resilience features are useful, to motivate the work. Further, to address the observed lacunae in cloud setups, the paper proposes and describes a service resilience framework that brings in autonomous cross-layer consciousness across cloud service layers for delivering improved service resilience. This framework is analyzed and explained with specific use-cases for availability and performance with goal-driven service resilience. y
Sequential backbone resonance assignment of AT-rich interaction domain of human BAF200
No full textBAF200 is a subunit of PBAF chromatin remodeling complex that contains an N-terminal AT-rich interaction domain (ARID). ARID domain in general has been shown to bind to the AT-rich DNA sequences. The human BAF200 ARID (similar to 110 residues) has the potential to bind the DNA sequences with high affinity, however, the structure and the exact contribution of hBAF200 ARID in PBAF functions as well its DNA binding specificities have not been established. In this study, we have expressed and purified the hBAF200 ARID for NMR studies. We report the complete backbone H-1, C-13, and N-15 chemical shift assignment and secondary structure of hBAF200 ARID domain