22,515 research outputs found
English funding of the Scottish armies in England and Ireland 1640-1648
The rebellion against Charles I's authority that began in Edinburgh in 1637 involved the Scots in successive invasions of England and armed intervention in Ireland. Historians have almost universally taken a negative view of Scottish involvement in these wars, because it has been assumed that the Scottish political leadership sacrificed all other considerations in order to pursue an unrealistic religious crusade. This article suggests that aspects of the Anglo-Scottish relationship need to be reappraised. Using estimates of English payments to the Scots during the 1640s, it will be argued that the Scottish leadership made pragmatic political decisions based on a practical appreciation of the country's military and fiscal capacity. Substantial payouts from the English parliament enabled the Scottish parliamentary regime to engage in military and diplomatic activities that the country could not otherwise have afforded. The 1643 treaty that brought the Scots into the English Civil War on the side of parliament contrasts favourably with the 1647 Engagement in support of the king. It will be shown that, although the English parliament did not honour all of its obligations to the Scots, it does not automatically follow that the alliance was a failure in financial terms
Mass distributions in a variational model
The time-dependent Hartree-Fock approach may be derived from a variational
principle and a Slater Determinant wavefunction Ansatz. It gives a good
description of nuclear processes in which one-body collisions dominate and has
been applied with success to giant resonances and collisions around the
barrier. It is inherently unable to give a good description of two-body
observables. A variational principle, due to Balian and Veneroni has been
proposed which can be geared to good reproduction of two-body observables.
Keeping the Slater Determinant Ansatz, and restricting the two-body observables
to be the squares of one-body observables, the procedure can be implemented as
a modification of the time-dependent Hartree-Fock procedure. Applications,
using the Skyrme effective interaction, are presented for the mass
distributions of fragments following de-excitation of the giant dipole
resonance in S-32. An illustration of the method's use in collisions is given.Comment: 5 pages, proceedings of XXXII Symposium on Nuclear Physics, Cocoyoc,
Mexic
Cause of the charge radius isotope shift at the \emph{N}=126 shell gap
We discuss the mechanism causing the `kink' in the charge radius isotope
shift at the N=126 shell closure. The occupation of the 1 neutron
orbital is the decisive factor for reproducing the experimentally observed
kink. We investigate whether this orbital is occupied or not by different
Skyrme effective interactions as neutrons are added above the shell closure.
Our results demonstrate that several factors can cause an appreciable
occupation of the 1 neutron orbital, including the magnitude of the
spin-orbit field, and the isoscalar effective mass of the Skyrme interaction.
The symmetry energy of the effective interaction has little influence upon its
ability to reproduce the kink.Comment: 4 pages, 4 figures, to be submitted to proceedings of INPC 201
Shapes and Dynamics from the Time-Dependent Mean Field
Explaining observed properties in terms of underlying shape degrees of
freedom is a well--established prism with which to understand atomic nuclei.
Self--consistent mean--field models provide one tool to understand nuclear
shapes, and their link to other nuclear properties and observables. We present
examples of how the time--dependent extension of the mean--field approach can
be used in particular to shed light on nuclear shape properties, particularly
looking at the giant resonances built on deformed nuclear ground states, and at
dynamics in highly-deformed fission isomers. Example calculations are shown of
Si in the first case, and Pu in the latter case.Comment: 9 pages, 5 figures, to appear in proceedings of International
Workshop "Shapes and Dynamics of Atomic Nuclei: Contemporary Aspects"
(SDANCA-15), 8-10 October 2015, Sofia, Bulgari
Hypervelocity impact microfoil perforations in the LEO space environment (LDEF, MAP AO-023 experiment)
The Microabrasion Foil Experiment comprises arrays of frames, each supporting two layers of closely spaced metallic foils and a back-stop plate. The arrays, deploying aluminum and brass foil ranging from 1.5 to some 30 microns were exposed for 5.78 years on NASA's LDEF at a mean altitude of 458 km. They were deployed on the North, South, East, West, and Space pointing faces; results presented comprise the perforation rates for each location as a function of foil thickness. Initial results refer primarily to aluminum of 5 microns thickness or greater. This penetration distribution, comprising 2,342 perforations in total, shows significantly differing characteristics for each detector face. The anisotropy confirms, incorporating the dynamics of particulate orbital mechanics, the dominance of incorporating extraterrestrial particulates penetrating thicknesses greater than 20 microns in Al foil, yielding fluxes compatible with hyperbolic geocentric velocities. For thinner foils, a disproportionate increase in flux of particles on the East, North, and South faces shows the presence of orbital particulates which exceed the extraterrestrial component perforation rate at 5 micron foil thickness by a factor of approx. 4
Free induction decay of a superposition stored in a quantum dot
We study the free evolution of a superposition initialized with high fidelity
in the neutral-exciton state of a quantum dot. Readout of the state at later
times is achieved by polarized photon detection, averaged over a large number
of cycles. By controlling the fine-structure splitting (FSS) of the dot with a
dc electric field, we show a reduction in the degree of polarization of the
signal when the splitting is minimized. In analogy with the "free induction
decay" observed in nuclear magnetic resonance, we attribute this to hyperfine
interactions with nuclei in the semiconductor. We numerically model this effect
and find good agreement with experimental studies. Our findings have
implications for storage of superpositions in solid-state systems and for
entangled photon pair emission protocols that require a small value of the FSS
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