15,610 research outputs found
^1S_0 pairing correlations in relativistic nuclear matter and the two-nucleon virtual state
We use the Gorkov formulation of the Dirac-Hartree-Fock-Bogoliubov
approximation to nuclear pairing to study the ^1S_0 nucleon-nucleon
correlations in nuclear matter. We find the short-range correlations of the
^1S_0 pairing fields to be almost identical to those of the two-nucleon virtual
state. We obtain mutually consistent results for the pairing fields, using
several different sets of effective interaction parameters, when we demand that
each of these sets places the virtual-state pole at its physical location.Comment: 11 pages, 9 PostScript figures, RevTex, submitted to Phys. Rev.
The importance of local band effects for ferromagnetism in hole doped LaCuO
Band calculations for supercells of LaBaCuO show that the
rigid band model for doping is less adequate than what is commonly assumed. In
particular, weak ferromagnetism (FM) can appear locally around clusters of high
Ba concentration. The clustering is important at large dilution and averaged
models for magnetism, such as the virtual crystal approximation, are unable to
stabilize magnetic moments. These results give a support to the idea that weak
FM can be the cause of the destruction of superconductivity at high hole
doping.Comment: 4 pages, 5 figures, accepted for publication in Physical Review
Letter
The short-run dynamics of long-run inflation policy
An examination of the short- and long-term implications of an inflation policy on real output, using a method that allows structural interpretation of a simple VAR applied to a macroeconomic system that includes real output and inflation.Inflation (Finance) ; Monetary policy ; Gross national product
Effective Widths and Effective Number of Phonons of Multiphonon Giant Resonances
We discuss the origin of the difference between the harmonic value of the
width of the multiphonon giant resonances and the smaller observed value.
Analytical expressions are derived for both the effective width and the average
cross-section. The contribution of the Brink-Axel mechanism in resolving the
discrepancy is pointed out.Comment: 9 pages, 4 figure
Inclusive Breakup Theory of Three-Body Halos
We present a recently developed theory for the inclusive breakup of
three-fragment projectiles within a four-body spectator model
\cite{CarPLB2017}, for the treatment of the elastic and inclusive non-elastic
break up reactions involving weakly bound three-cluster nuclei in
/ collisions. The four-body theory is an extension of the
three-body approaches developed in the 80's by Ichimura, Autern and Vincent
(IAV) \cite{IAV1985}, Udagawa and Tamura (UT) \cite{UT1981} and Hussein and
McVoy (HM) \cite{HM1985}. We expect that experimentalists shall be encouraged
to search for more information about the system in the elastic
breakup cross section and that also further developments and extensions of the
surrogate method will be pursued, based on the inclusive non-elastic breakup
part of the spectrum.Comment: 8 pages, 3 figures, Contribution to the Proceedings of Fusion17:
"International Conference on Heavy-Ion Collisions at Near-Barrier Energies",
20-24 February 2017 Hobart, Tasmania, Australi
A rule-based assistive control algorithm for safe navigation for a powered wheelchair
This paper addresses the problem of safe navigation in an environment with randomly placed static obstacles.
We convert a commercial powered wheelchair into a semiautonomous vehicle with limited sight (environment awareness),
by instrumenting it using off-the-shelf ultrasonic sensors and
associated electronic boards (Arduino). In the continuity of
our previous work where we had used stochastic dynamic
programming to formulate optimization problems which led
to relatively large size look-up tables that can be used as
supervisory control, here we propose to extract rules using those
results (that data). The advantage of this approach is a lowcomputational cost for future online implementation, and the
drawback is a suboptimal policy. The feasibility is assessed by
running simulations in a fairly realistic environment (Unity3D)
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