8,613 research outputs found
The intensity of the ancient lunar field from magnetic studies on lunar samples
Palaeointensity determination on Apollo 11, 16, and 17 rocks have indicated that from 3.9 to 4.0 AE ago the strength of the surface lunar magnetic field was about 1.3 Oe, while there is evidence from younger rocks that a field of about one quarter of this value was present at a later time (3.6 AE)
Inclusion of non-spherical components of the Pauli blocking operator in (p,p') reactions
We present the first calculations of proton elastic and inelastic scattering
in which the Pauli blocking operator contains the leading non-spherical
components as well as the usual spherical (angle-averaged) part. We develop a
formalism for including the contributions to the effective nucleon-nucleon
interaction from the resulting new G-matrix elements that extend the usual
two-nucleon spin structure and may not conserve angular momentum. We explore
the consequences of parity conservation, time reversal invariance, and
nucleon-nucleon antisymmetrization for the new effective interaction. Changes
to the calculated cross section and spin observables are small in the energy
range from 100 to 200 MeV.Comment: 24 pages, 4 figures, to be published in Physical Review
Synthesis of calculational methods for the design and analysis of radiation shields for nuclear rocket systems. Volume 2 - Analysis of radiation measurements in a nuclear rocket propellant tank mockup using simulated liquid hydrogen
Calculational methods for nuclear rocket radiation shield design - analysis of radiation measurements in nuclear rocket propellant tank mockup using simulated liquid hydroge
A Shell of Thermal X-ray Emission Associated with the Young Crab-like Remnant 3C58
Deep X-ray imaging spectroscopy of the bright pulsar wind nebula 3C58
confirms the existence of an embedded thermal X-ray shell surrounding the
pulsar PSR J0205+6449. Radially resolved spectra obtained with the XMM-Newton
telescope are well-characterized by a power-law model with the addition of a
soft thermal emission component in varying proportions. These fits reproduce
the well-studied increase in the spectral index with radius attributed to
synchrotron burn-off of high energy electrons. Most interestingly, a radially
resolved thermal component is shown to map out a shell-like structure ~6' in
diameter. The presence of a strong emission line corresponding to the Ne IX
He-like transition requires an overabundance of ~3 x [Ne/Ne(sun)] in the
Raymond-Smith plasma model. The best-fit temperature kT ~ 0.23 keV is
essentially independent of radius for the derived column density of N_H = (4.2
+/- 0.1)E21 per cm squared. Our result suggests that thermal shells can be
obscured in the early evolution of a supernova remnant by non-thermal pulsar
wind nebulae emission; the luminosity of the 3C58 shell is more than an order
of magnitude below the upper limit on a similar shell in the Crab Nebula. We
find the shell centroid to be offset from the pulsar location. If this neutron
star has a velocity similar to that of the Crab pulsar, we derive an age of
3700 yr and a velocity vector aligned with the long axis of the PWN. The shell
parameters and pulsar offset add to the accumulating evidence that 3C58 is not
the remnant of the supernova of CE 1181.Comment: 7 pages, 8 figures, 2 tables, Latex emulateapj style. To appear in
the Astrophysical Journa
Elementary excitations in the gapped phase of a frustrated S=1/2 spin ladder: from spinons to the Haldane triplet
We use the variational matrix-product ansatz to study elementary excitations
in the S=1/2 ladder with additional diagonal coupling, equivalent to a single
S=1/2 chain with alternating exchange and next-nearest neighbor interaction. In
absence of alternation the elementary excitation consists of two free S=1/2
particles ("spinons") which are solitons in the dimer order. When the
nearest-neighbor exchange alternates, the "spinons" are confined into one S=1
excitation being a soliton in the generalized string order. Variational results
are found to be in a qualitative agreement with the exact diagonalization data
for 24 spins. We argue that such an approach gives a reasonably good
description in a wide range of the model parameters.Comment: RevTeX, 13 pages, 11 embedded figures, uses psfig and multico
Fluid inclusion evidence for the nature of fluids associated with recrystallization of quartzites in the EJB contact Aureole, California
The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Title from PDF of title page (University of Missouri--Columbia, viewed on January 15, 2010).Thesis advisor: Dr. Peter Nabelek.Includes bibliographical references.M.S. University of Missouri--Columbia 2009.Dissertations, Academic -- University of Missouri--Columbia -- Geological sciences.The purpose of this study was to look at the control of fluids and fluid composition on recrystallization of quartzites in the Eureka Valley - Joshua Flat - Beer Creek pluton contact aureole (EJB), in the White - Inyo Mountains of eastern California. The aureole shows varying degrees of recrystallization and deformation. Fluid inclusions were analyzed by microthermometry, laser ablation - inductively coupled plasma - mass spectrometry, and Raman spectoscopy, to define the compositions of fluids that were responsible for the contrasting styles of deformation and recrystallization. The inclusions were grouped into three types based on composition: Type I inclusions are strictly aqueous inclusions with various salts. Type II inclusions are mixed aqueous - carbonic inclusions with an aqueous liquid phase and a vapor bubble with a double meniscus of CO2 fluid and vapor. Type III inclusions have an aqueous - hydrogen sulfide liquid and a single - phase CO₂ - CH₄ vapor. Isochores were developed using LA - ICP - MS and microthermometry data to determine the trapping environment of the inclusions. The isochores show an extensive range of P - T conditions of trapping for all types of inclusions, indicating that the P - T history of the EJB aureole is complex, and that all inclusions appear to have undergone the same complicated history. This study suggests that the fluids trapped in the EJB aureole quartzites are metamorphic from the Antler orogeny. Fluid composition has played a role in the recrystallization history of this quartzite. It is also probable that the pattern of recrystallization seen in the EJB aureole has strongly been influenced by the amount of strain taken up by the Mule Spring unit, allowing theinner aureole to be unaffected by the pluton intrusion. The higher Ca concentrations in fluids in the inner aureole may also have retarded recrystallization of quartzite in the inner aureole
Does the keeping of a professional development profile lead to an enhanced self awareness in newly qualified secondary teachers? A study conducted in a large UK University
Looking at how the professional development profile leads to an enhanced self awareness in newly qualified secondary teachers.</p
After Katrina: A Critical Look at FEMA\u27s Failure to Provide Housing for Victims of Natural Disasters
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