3,653 research outputs found
The application of semiconductors to quasi- optical isolators for use at submillimeter wavelengths
Semiconductor application to quasi-optical isolators - nonreciprocal reflection beam isolator and far infrared isolators using Faraday rotatio
Rank/select queries over mutable bitmaps
The problem of answering rank/select queries over a bitmap is of utmost importance for many succinct data structures. When the bitmap does not change, many solutions exist in the theoretical and practical side. In this work we consider the case where one is allowed to modify the bitmap via a flip(i) operation that toggles its ith bit. By adapting and properly extending some results concerning prefix-sum data structures, we present a practical solution to the problem, tailored for modern CPU instruction sets. Compared to the state-of-the-art, our solution improves runtime with no space degradation. Moreover, it does not incur in a significant runtime penalty when compared to the fastest immutable indexes, while providing even lower space overhead. (C) 2021 Elsevier Ltd. All rights reserved
Role of dynamic Jahn-Teller distortions in Na2C60 and Na2CsC60 studied by NMR
Through 13C NMR spin lattice relaxation (T1) measurements in cubic Na2C60, we
detect a gap in its electronic excitations, similar to that observed in
tetragonal A4C60. This establishes that Jahn-Teller distortions (JTD) and
strong electronic correlations must be considered to understand the behaviour
of even electron systems, regardless of the structure. Furthermore, in metallic
Na2CsC60, a similar contribution to T1 is also detected for 13C and 133Cs NMR,
implying the occurence of excitations typical of JT distorted C60^{2-} (or
equivalently C60^{4-}). This supports the idea that dynamic JTD can induce
attractive electronic interactions in odd electron systems.Comment: 3 figure
Nonequilibrium steady states of driven magnetic flux lines in disordered type-II superconductors
We investigate driven magnetic flux lines in layered type-II superconductors
subject to various configurations of strong point or columnar pinning centers
by means of a three-dimensional elastic line model and Metropolis Monte Carlo
simulations. We characterize the resulting nonequilibrium steady states by
means of the force-velocity / current-voltage curve, static structure factor,
mean vortex radius of gyration, number of double-kink and half-loop
excitations, and velocity / voltage noise spectrum. We compare the results for
the above observables for randomly distributed point and columnar defects, and
demonstrate that the three-dimensional flux line structures and their
fluctuations lead to a remarkable variety of complex phenomena in the
steady-state transport properties of bulk superconductors.Comment: 23 pages, IOP style, 18 figures include
An Eccentric Eclipsing Binary: CGAur
In this study, we present CG Aur's photometric observations obtained in the
observing seasons 2011 and 2012, the first available multi-colour light curves.
Their shape indicates that the system is an Algol binary. The light curve
analyses reveal that CG Aur is a detached binary system with an effective
temperature difference between the components, approximately 1000 K. The first
estimate of the absolute dimensions of the components indicated that the system
locates on the main sequence in the HR diagram. The primary component is
slightly evolved from the ZAMS.Comment: 18 pages, 6 figures, 3 table
High Field magnetospectroscopy to probe the 1.4eV Ni color center in diamond
A magneto-optical study of the 1.4 eV Ni color center in boron-free synthetic
diamond, grown at high pressure and high temperature, has been performed in
magnetic fields up to 56 T. The data is interpreted using the effective spin
Hamiltonian of Nazar\'e, Nevers and Davies [Phys. Rev. B 43, 14196 (1991)] for
interstitial Ni with the electronic configuration and effective
spin . Our results unequivocally demonstrate the trigonal symmetry of
the defect which preferentially aligns along the [111] growth direction on the
(111) face, but reveal the shortcomings of the crystal field model for this
particular defect.Comment: 12 pages, 13 figures, submitted to PR
On Detection of Black Hole Quasi-Normal Ringdowns: Detection Efficiency and Waveform Parameter Determination in Matched Filtering
Gravitational radiation from a slightly distorted black hole with ringdown
waveform is well understood in general relativity. It provides a probe for
direct observation of black holes and determination of their physical
parameters, masses and angular momenta (Kerr parameters). For ringdown searches
using data of gravitational wave detectors, matched filtering technique is
useful. In this paper, we describe studies on problems in matched filtering
analysis in realistic gravitational wave searches using observational data.
Above all, we focus on template constructions, matches or signal-to-noise
ratios (SNRs), detection probabilities for Galactic events, and accuracies in
evaluation of waveform parameters or black hole hairs. We have performed
matched filtering analysis for artificial ringdown signals which are generated
with Monte-Carlo technique and injected into the TAMA300 observational data. It
is shown that with TAMA300 sensitivity, the detection probability for Galactic
ringdown events is about 50% for black holes of masses greater than with SNR . The accuracies in waveform parameter estimations
are found to be consistent with the template spacings, and resolutions for
black hole masses and the Kerr parameters are evaluated as a few % and , respectively. They can be improved up to and for events
of by using fine-meshed template bank in the hierarchical
search strategy.Comment: 10 pages, 10 figure
Stochastic backgrounds of gravitational waves from extragalactic sources
Astrophysical sources emit gravitational waves in a large variety of
processes occurred since the beginning of star and galaxy formation. These
waves permeate our high redshift Universe, and form a background which is the
result of the superposition of different components, each associated to a
specific astrophysical process. Each component has different spectral
properties and features that it is important to investigate in view of a
possible, future detection. In this contribution, we will review recent
theoretical predictions for backgrounds produced by extragalactic sources and
discuss their detectability with current and future gravitational wave
observatories.Comment: 10 pages, 9 figures, proceedings of the GWDAW 10 Conference,
submitted to Class. & Quantum Gra
The application of semiconductors to quasi- optical and waveguide isolators for use at millimeter wavelengths
Utilization of anisotropic effects in semiconductor plasmas for development of millimeter wavelength isolator
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