6,159 research outputs found
J06587-5558 -- A Very Unusual Polarised Radio Source
We have found a peculiar radio source in the field of one of the hottest
known clusters of galaxies 1E0657-56. It is slightly extended, highly polarised
(54% at 8.8GHz) and has a very steep spectrum, with alpha ~ -1 at 1.3 GHz,
steepening to ~ -1.5 at 8.8GHz (S \propto nu^alpha). No extragalactic sources
are known with such high integrated polarisation, and sources with spectra as
steep as this are rare. In this paper, we report the unusual properties of the
source J06587-5558 and speculate on its origin and optical identification.Comment: 5 pages, 6 figures, accepted by MNRAS letter
Prediction Model for the Life of Nickel-cadmium Batteries in Geosynchronous Orbit Satellites
A mathematical model is described which predicts the service life of nickel-cadmium batteries designed for geosynchronous orbit satellites. Regression analysis technique is used to analyze orbital data on second generation trickle charged batteries. The model gives average cell voltage as a function of design parameters, operating parameters and time. The voltage model has the properties of providing a good fit to the data, good predictive capability, and agreement with known battery performance characteristics. Average cell voltage can be predicted to within 0.02 volts for up to 8 years. This modeling shows that these batteries will operate reliably for 10 years. Third-generation batteries are expected to operate even longer
Lifetime statistics of quantum chaos studied by a multiscale analysis
In a series of pump and probe experiments, we study the lifetime statistics
of a quantum chaotic resonator when the number of open channels is greater than
one. Our design embeds a stadium billiard into a two dimensional photonic
crystal realized on a Silicon-on-insulator substrate. We calculate resonances
through a multiscale procedure that combines graph theory, energy landscape
analysis and wavelet transforms. Experimental data is found to follow the
universal predictions arising from random matrix theory with an excellent level
of agreement.Comment: 4 pages, 6 figure
Using School-Based Career Development to Support College and Career Readiness: An Integrative Review
For current college and career readiness efforts to be effective, it is important to recognize the value and contribution of career development activities in schools and take a critical look at the most effective strategies, programs, and research in this area. This integrative review synthesizes research related to the impact of school-based career development on student achievement, retention, post-secondary transitions, and other career-related outcomes. Using an iterative key word search, in multiple scholarly databases including JSTOR, PsycInfo, and EBSCOhost Fulltext Finder, 157 studies published in years 1961-2017 were selected for this review. Findings are examined within the context of college and career readiness. Implications for school counseling research, evaluation, practice, and policy are discussed
The bosonic Kondo effect
The Kondo effect is associated with the formation of a many-body ground state
that contains a quantum-mechanical entanglement between a (localized) fermion
and the free fermions. We show that a bosonic version of the Kondo effect can
occur in degenerate atomic Fermi gases near the Feshbach resonance. We also
discuss how this bosonic Kondo effect can be observed experimentally.Comment: 4 pages, 2 figures, some references added, some removed. More
comments adde
Analyticity of the SRB measure for a class of simple Anosov flows
We consider perturbations of the Hamiltonian flow associated with the
geodesic flow on a surface of constant negative curvature. We prove that, under
a small perturbation, not necessarely of Hamiltonian character, the SRB measure
associated to the flow exists and is analytic in the strength of the
perturbation. An explicit example of "thermostatted" dissipative dynamics is
constructed.Comment: 23 pages, corrected typo
Speed and entropy of an interacting continuous time quantum walk
We present some dynamic and entropic considerations about the evolution of a
continuous time quantum walk implementing the clock of an autonomous machine.
On a simple model, we study in quite explicit terms the Lindblad evolution of
the clocked subsystem, relating the evolution of its entropy to the spreading
of the wave packet of the clock. We explore possible ways of reducing the
generation of entropy in the clocked subsystem, as it amounts to a deficit in
the probability of finding the target state of the computation. We are thus
lead to examine the benefits of abandoning some classical prejudice about how a
clocking mechanism should operate.Comment: 25 pages, 14 figure
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