23,042 research outputs found
The B3-Vla CSS sample. III: Evn & Merlin images at 18 cm
EVN and MERLIN observations at 18 cm are presented for 18 Compact
Steep--spectrum radio Sources (CSSs) from the B3-VLA CSS sample. These sources
were marginally resolved in previous VLA A-configuration observations at 4.9
and 8.4 GHz or had peculiar morphologies, two of them looking like core-jets.
The MERLIN images basically confirm the VLA structures at 8.4 GHz while the EVN
and/or the combined images reveal several additional details.Comment: 17 pages, many low resoltion figures, A&A accepted. A higher
resolution gzipped postscript file can be found at
http://www.ira.cnr.it/~ddallaca/h3443.ps.g
An S-shaped arc in the galaxy cluster RXJ0054.0-2823
The center of the galaxy cluster RX J0054.0-2823 at z = 0.292 is a
dynamically active region which includes an interacting system of three
galaxies surrounded by a large halo of intra-cluster light. We report here the
discovery of an S-shaped feature of total length 11 arcsec in the central
region of this cluster and discuss its physical nature. We test the
gravitational lensing assumption by doing a mass modelling of the central part
of the galaxy cluster. We very naturally reproduce position and form of this
S-shape feature as a gravitationally lensed background object at redshift
between 0.5 and 1.0. We conclude that the lensing nature is the very probable
explanation for this S-shaped arc; the ultimate proof will be the spectroscopic
confirmation by measuring the high redshift of this elongated feature with
surface brightness V~24mag/arcsec2.Comment: 6 pages, accepted for publication in A&
Development of a two-dimensional virtual pixel X-ray imaging detector for time-resolved structure research
An interpolating two-dimensional X-ray imaging detector based on a single
photon counter with gas amplification by GEM (gas electron multiplier)
structures is presented. The detector system can be used for time-resolved
structure research down to the microsecond-time domain. The prototype detector
has been tested at the SAXS beamline at ELETTRA synchrotron light source with a
beam energy of 8 keV to test its capabilities in the rough beamline
environment. The imaging performance is examined with apertures and standard
diffraction targets. Finally, the application in a time-resolved lipid
temperature jump experiment is presented.Comment: 10 pages, 14 figures, accepted for publication in J. Synchrotron Rad,
revised version, paper shortened, minor change
A Deep Radio Survey of Abell 2125 III: The Cluster Core - Merging and Stripping
We use radio, near-IR, optical, and X-ray observations to examine dynamic
processes in the central region of Abell 2125. In addition to the central
triple, including members of both major dynamical subsystems identified from a
redshift survey, this region features a galaxy showing strong evidence for
ongoing gas stripping during a high-velocity passage through the gas in the
cluster core. The disk galaxy C153 exhibits a plume stretching toward the
cluster center seen in soft X-rays by Chandra, parts of which are also seen in
[O II] emission and near-UV continuum light. HST imaging shows a distorted
disk, with star-forming knots asymmetrically distributed and remnant spiral
structure possibly defined by dust lanes. The stars and ionized gas in its disk
are kinematically decoupled, demonstrating that pressure stripping must be
important, and that tidal disruption is not the only mechanism at work.
Comparison of the gas properties seen in the X-ray and optical data on the
plume highlight significant features of the history of stripped gas in the
intracluster medium. The nucleus of C153 also hosts an AGN, shown by the weak
and distorted extended radio emission and a radio compact core. The unusual
strength of the stripping signatures in this instance is likely related to the
high relative velocity of the galaxy with respect to the intracluster medium,
during a cluster/cluster merger, and its passage very near the core of the
cluster. Another sign of recent dynamical events is diffuse starlight
asymmetrically placed about the central triple in a cD envelope. Transient and
extreme dynamical events as seen in Abell 2125 may be important drivers of
galaxy evolution in the cores of rich clusters.Comment: 36 pages, 16 figures, accepted AJ, paper with full resolution figures
is available at http:www.aoc.nrao.edu/~fowen/papers/a2125/a2125paper3.ps.g
VLA Observations of a Complete Sample of Radio Loud Quasars between redshifts 2.5 and 5.28: I. high-redshift sample summary and the radio images
We present high resolution (arcsecond or better) observations made with the
Karl G. Jansky Very Large Array of 123 radio-loud quasars with redshifts in the
range that form a complete flux limited sample ( mJy at 1.4 GHz or 5 GHz). Where possible, we used previous high resolution
VLA observations (mainly A array at 1.4, 5 and 8 GHz) from the NRAO archive and
re-imaged them (43 sources). For the remainder, new observations were made in
the A array at 1.4 and 5 GHz. We show images of the 61 resolved sources, and
list structural properties of all of them. Optical data from the SDSS are
available for nearly every source. This work represents a significant increase
in the number of high redshift quasars with published radio structures, and
will be used to study the properties and evolution of luminous radio sources in
the high redshift universe
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Cryo-EM Studies of TMEM16F Calcium-Activated Ion Channel Suggest Features Important for Lipid Scrambling.
As a Ca2+-activated lipid scramblase and ion channel that mediates Ca2+ influx, TMEM16F relies on both functions to facilitate extracellular vesicle generation, blood coagulation, and bone formation. How a bona fide ion channel scrambles lipids remains elusive. Our structural analyses revealed the coexistence of an intact channel pore and PIP2-dependent protein conformation changes leading to membrane distortion. Correlated to the extent of membrane distortion, many tightly bound lipids are slanted. Structure-based mutagenesis studies further reveal that neutralization of some lipid-binding residues or those near membrane distortion specifically alters the onset of lipid scrambling, but not Ca2+ influx, thus identifying features outside of channel pore that are important for lipid scrambling. Together, our studies demonstrate that membrane distortion does not require open hydrophilic grooves facing the membrane interior and provide further evidence to suggest separate pathways for lipid scrambling and ion permeation
Systematic approach to nonlinear filtering associated with aggregation operators. Part 1. SISO-filters
There are various methods to help restore an image from noisy distortions. Each technique has its advantages and disadvantages. Selecting the appropriate method plays a major role in getting the desired image. Noise removal or noise reduction can be done on an image by linear or nonlinear filtering. The more popular linear technique is based on average (on mean) linear operators. Denoising via linear filters normally does not perform satisfactorily since both noise and edges contain high frequencies. Therefore, any practical denoising model has to be nonlinear. In this work, we introduce and analyze a new class of nonlinear SISO-filters that have their roots in aggregation operator theory. We show that a large body of non-linear filters proposed to date constitute a proper subset of aggregation filters. (C) 2017 The Authors. Published by Elsevier Ltd.This work was supported by grants the RFBR No. 17-07-00886 and by Ural State Forest Engineering's Center of Excellence in "Quantum and Classical Information Technologies for Remote Sensing Systems"
Comparative study on structural, electrical transport and magnetic properties of cr-doped in charge-ordered Pr0.75Na0.25Mn1-Xcrxo3 and Nd0.75Na0.25Mn1-Ycryo3 manganites
Cr doping in charge-ordered Pr0.75Na0.25Mn1-xCrxO3 and Nd0.75Na0.25Mn1-yCryO3 have been synthesized using conventional solid-state method to investigate its effect on structural, electrical transport and magnetic properties. X-ray diffraction (XRD) analysis for both compounds showed that the samples were crystallized in an orthorhombic structure with Pnma group. The unit cell volume value decrease as the Cr-doped increased indicating the possibility of Mn3+ ion was replaced by Cr3+ due to the different of ionic radius. The temperature dependence of electrical resistivity showed an insulating behavior down to the lower temperature the both parent compound (x = 0 and y = 0). Successive substitution of Cr at Mn-site in Pr0.75Na0.25Mn1-xCrxO3 manganites induced the metal-insulator (MI) transition temperature around TMI~120 K and TMI~122 K for x = 0.02 and x = 0.04 samples respectively suggestively due to the enhancement of double-exchange (DE) mechanism as a result of suppress the CO state. Analysis of resistivity data of dlnρ/dT-1 vs. T in Nd0.75Na0.25Mn1-yCryO3 manganite, showed a peak around 210 K and 160 K for y = 0 and 0.02 samples respectively while no peak was observed for y = 0.05 sample indicate the charge-ordered (CO) weakened. AC susceptibility, χ ’ measurements in Pr0.75Na0.25Mn1-xCrxO3 exhibits paramagnetic to ferromagnetic-like with curie temperature, TC increases from 132 K for x = 0.02 to 141 K for x = 0.04 with Cr content indicate the suppression of CO state meanwhile in Nd0.75Na0.25Mn1-yCryO3 showed paramagnetic to anti-ferromagnetic transition as Neel temperature TN increases from 115 K for y = 0.02 to 125 K for y = 0.05
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