9,439 research outputs found
A Generalization of Abel Inversion to non axisymmetric density distribution
Abel Inversion is currently used in laser-plasma studies in order to estimate
the electronic density from the phase-shift map obtained
via interferometry. The main limitation of the Abel method is due to the
assumption of axial symmetry of the electronic density, which is often hardly
fulfilled. In this paper we present an improvement to the Abel inversion
technique in which the axial symmetry condition is relaxed by means of a
truncated Legendre Polinomial expansion in the azimutal angle. With the help of
simulated interferograms, we will show that the generalized Abel inversion
generates accurate densities maps when applied to non axisymmetric density
sources
Battlefields, Tools, and Targets: Archives and Armed Conflict
Kenneth Foote notes in his seminal book on memorials Shadowed Ground that, Every society in every period has borne witness to war, disaster, violence and tragedy. The universal nature of conflict is, of course, well known, so it is perhaps not surprising that, as with many other institutions of society, archives have been impacted by human violence and destruction. Indeed, the birth of the archival profession is often closely associated with one of the most important wars in history-the French Revolution of 1789. In the aftermath of the revolution, the new French government sought to make the records of the republic open to the people of France for the first time, in the process creating the first National Archives and establishing modern archival principles. It is perhaps fitting then, that the modern archival profession should consider its roots in conflict, since war and archives have consistently interacted throughout history, albeit in many different ways
Multiplication Fact Fluency and Multiple Intelligences in a Third Grade Classroom
The purpose of this quasi-experimental study was to examine if teaching students their multiplication facts in a way that utilized their multiple intelligence strength would be a more effective way of teaching students their multiplication facts than having students learn their multiplication facts through rote memorization only. All four groups who received a teaching of multiplication facts intervention made gains in learning their multiplication facts. The three multiple intelligence groups did make more gains in learning more facts, than the one group who only learned their facts through rote memorization. However, the rote memorization group was able to give more facts automatically in the post assessment when compared with the other three multiple intelligence groups
The Yarkovsky Drift's Influence on NEAs: Trends and Predictions with NEOWISE Measurements
We used WISE-derived geometric albedos (p_V) and diameters, as well as
geometric albedos and diameters from the literature, to produce more accurate
diurnal Yarkovsky drift predictions for 540 near-Earth asteroids (NEAs) out of
the current sample of \sim 8,800 known objects. As ten of the twelve objects
with the fastest predicted rates have observed arcs of less than a decade, we
list upcoming apparitions of these NEAs to facilitate observations.Comment: Accepted for publication by The Astronomical Journal. 41 pages, 3
figure
Legislating Morality: The Effects Of Tax Law Complexity On Taxpayers Attitudes
This paper addresses the effects of tax law complexity on the behavior of taxpayers. A particular focus is the effect of tax law complexity on taxpayers perceptions of the morality of taking deductions that might be disallowed. The topic of taxpayer morality is addressed in terms of the broader concept of deterrence theory, which suggests that deterrence factors include formal punishment, informal social punishment and the guilt that would be felt if a behavior were perceived to be immoral. Tax law complexity may give rise to the perception that taking a questionable deduction would be socially acceptable tax avoidance rather than socially unacceptable tax evasion, and that taking a questionable deduction is morally acceptable. It is hypothesized that greater tax law complexity is associated with less perception that taking questionable deductions is immoral, and that less perception that taking questionable deductions is immoral is associated with greater inclination to take questionable deductions. Accordingly, it is hypothesized that greater tax law complexity is associated with greater inclination to take questionable deductions. The study entailed an experimental survey in which subjects evaluated hypothetical scenarios in which the opportunity existed to save taxes by taking a deduction that might be disallowed. ANOVA and Regression results were consistent with the hypotheses
The Euphrosyne family's contribution to the low albedo near-Earth asteroids
The Euphrosyne asteroid family is uniquely situated at high inclination in
the outer Main Belt, bisected by the nu_6 secular resonance. This large, low
albedo family may thus be an important contributor to specific subpopulations
of the near-Earth objects. We present simulations of the orbital evolution of
Euphrosyne family members from the time of breakup to the present day, focusing
on those members that move into near-Earth orbits. We find that family members
typically evolve into a specific region of orbital element-space, with
semimajor axes near ~3 AU, high inclinations, very large eccentricities, and
Tisserand parameters similar to Jupiter family comets. Filtering all known NEOs
with our derived orbital element limits, we find that the population of
candidate objects is significantly lower in albedo than the overall NEO
population, although many of our candidates are also darker than the Euphrosyne
family, and may have properties more similar to comet nuclei. Followup
characterization of these candidates will enable us to compare them to known
family properties, and confirm which ones originated with the breakup of (31)
Euphrosyne.Comment: Accepted for publication in Ap
Pressures measured in flight on the aft fuselage and external nozzle of a twin-jet fighter
Fuselage, boundary layer, and nozzle pressures were measured in flight for a twin jet fighter over a Mach number range from 0.60 to 2.00 at test altitudes of 6100, 10,700, and 13,700 meters for angles of attack ranging from 0 deg to 7 deg. Test data were analyzed to find the effects of the propulsion system geometry. The flight variables, and flow interference. The aft fuselage flow field was complex and showed the influence of the vertical tail, nacelle contour, and the wing. Changes in the boattail angle of either engine affected upper fuselage and lower fuselage pressure coefficients upstream of the nozzle. Boundary layer profiles at the forward and aft locations on the upper nacelles were relatively insensitive to Mach number and altitude. Boundary layer thickness decreased at both stations as angle of attack increased above 4 deg. Nozzle pressure coefficient was influenced by the vertical tail, horizontal tail boom, and nozzle interfairing; the last two tended to separate flow over the top of the nozzle from flow over the bottom of the nozzle. The left nozzle axial force coefficient was most affected by Mach number and left nozzle boattail angle. At Mach 0.90, the nozzle axial force coefficient was 0.0013
Synthetic Spectra of Hydrodynamic Models of Type Ia Supernovae
We present detailed NLTE synthetic spectra of hydrodynamic SNe Ia models. We
make no assumptions about the form of the spectrum at the inner boundary. We
calculate both Chandrasekhar-mass deflagration models and sub-Chandrasekhar
``helium detonators.'' Gamma-ray deposition is handled in a simple, accurate
manner. We have parameterized the storage of energy that arises from the time
dependent deposition of radioactive decay energy in a reasonable manner, that
spans the expected range. We find that the Chandrasekhar-mass deflagration
model W7 of Nomoto etal shows good agreement with the observed spectra of SN
1992A and SN 1994D, particularly in the UV, where our models are expected to be
most accurate. The sub-Chandrasekhar models do not reproduce the UV deficit
observed in normal SNe Ia. They do bear some resemblance to sub-luminous SNe
Ia, but the shape of the spectra (i.e. the colors) are opposite to that of the
observed ones and the intermediate mass element lines such as Si II, and Ca II
are extremely weak, which seems to be a generic difficulty of the models.
Although the sub-Chandrasekhar models have a significant helium abundance
(unlike Chandrasekhar-mass models), helium lines are not prominent in the
spectra near maximum light and thus do not act as a spectral signature for the
progenitor.Comment: submitted to ApJ, 26 pages, 10 figures, uses LaTeX styles aasms4.sty
and natbib.sty Also available at: http://www.nhn.ou.edu/~baron
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