20,206 research outputs found
A 3D radiative transfer framework: VII. Arbitrary velocity fields in the Eulerian frame
A solution of the radiative-transfer problem in 3D with arbitrary velocity
fields in the Eulerian frame is presented. The method is implemented in our 3D
radiative transfer framework and used in the PHOENIX/3D code. It is tested by
comparison to our well- tested 1D co-moving frame radiative transfer code,
where the treatment of a monotonic velocity field is implemented in the
Lagrangian frame. The Eulerian formulation does not need much additional memory
and is useable on state-of-the-art computers, even large-scale applications
with 1000's of wavelength points are feasible
Feasibility of an Incoherent-scatter Radar Aboard the Space Shuttle
The results of a preliminary study to investigate the feasibility of conducting an incoherent scatter radar experiment on board the space shuttle are presented. The results indicate that such an experiment is technically feasible. The more difficult questions to answer are whether the system can be made flexible enough to justify the problems and costs involved. The design parameters and the tradeoffs that are available in the consideration of these questions are evaluated. Some of the more serious limitations pertain to: (1) the presence of ground clutter and F region auroral clutter; (2) available average power; (3) weight and volume associated with required antenna size, transmitter, and energy storage devices; and (4) antenna breakdown associated with high power transmitter problems
The Bodily Movements of Liars
We measured the continuous bodily motion of participants as they lied to experimenters. These lies were spontaneous rather than elicited, and occurred for different motivations. In one situation, participants were given the opportunity to lie about their performance on a maths test in order to win money. In another, they witnessed one experimenter accidentally break a laptop. When asked what had happened, participants were motivated to lie and deny any knowledge. Across these situations, participants lied 61% of the time, allowing us to contrast the body movements of liars with truth tellers as they answered neutral and critical questions. Those who lied had significantly reduced bodily motion. In one case this motion appeared before the experimenter had even asked the critical question. We conclude that a person’s bodily dynamics can be indicative of their cognitive and effective states, even when they would rather conceal them
Capital’s humpback bridge: ‘financialisation’ and the rate of turnover in Marx’s economic theory
The article aims to shed light on the role played by the ‘rate of turnover’ of capital in Karl Marx’s economic theory. Oddly enough, such a concept has been neglected by the most part of Marx’s scholars and exegetes, as it is demonstrated by the small number of scientific works dealing with it. Yet, the rate of turnover is a key-category in Marxian analysis, as it enables Marx to address the impact of the improvement in finance and other unproductive industries on the capitalist process of creation (and realisation) of surplus-value. The evidence from the new philological edition of Marx and Engel’s writings (MEGA2) further strengthens this insight. The main goal of the paper is, therefore, threefold: first, to bridge the gap in the literature dealing with the Volume Two of Capital; second, to provide a re-definition of several Marxian concepts in the light of the role played by the rate of turnover of capital; third, to analyse the effect of the developments in the banking & finance industry on the turnover rate and, thereby, on the general rate of profit
Detailed Spectral Modeling of a 3-D Pulsating Reverse Detonation Model: Too Much Nickel
We calculate detailed NLTE synthetic spectra of a Pulsating Reverse
Detonation (PRD) model, a novel explosion mechanism for Type Ia supernovae.
While the hydro models are calculated in 3-D, the spectra use an angle averaged
hydro model and thus some of the 3-D details are lost, but the overall average
should be a good representation of the average observed spectra. We study the
model at 3 epochs: maximum light, seven days prior to maximum light, and 5 days
after maximum light. At maximum the defining Si II feature is prominent, but
there is also a prominent C II feature, not usually observed in normal SNe Ia
near maximum. We compare to the early spectrum of SN 2006D which did show a
prominent C II feature, but the fit to the observations is not compelling.
Finally we compare to the post-maximum UV+optical spectrum of SN 1992A. With
the broad spectral coverage it is clear that the iron-peak elements on the
outside of the model push too much flux to the red and thus the particular PRD
realizations studied would be intrinsically far redder than observed SNe Ia. We
briefly discuss variations that could improve future PRD models.Comment: 15 pages, 4 figures, submitted to Ap
3D Radiative Transfer with PHOENIX
Using the methods of general relativity Lindquist derived the radiative
transfer equation that is correct to all orders in v/c. Mihalas developed a
method of solution for the important case of monotonic velocity fields with
spherically symmetry. We have developed the generalized atmosphere code
PHOENIX, which in 1-D has used the framework of Mihalas to solve the radiative
transfer equation (RTE) in 1-D moving flows. We describe our recent work
including 3-D radiation transfer in PHOENIX and particularly including moving
flows exactly using a novel affine method. We briefly discuss quantitative
spectroscopy in supernovae.Comment: 13 pages, 9 figures, to appear in Recent Directions in Astrophysical
Quantitative Spectroscopy and Radiation Hydrodynamics, Ed. I. Hubeny,
American Institute of Physics (2009
Incommensurate phonon anomaly and the nature of charge density waves in cuprates
While charge density wave (CDW) instabilities are ubiquitous to
superconducting cuprates, the different ordering wavevectors in various cuprate
families have hampered a unified description of the CDW formation mechanism.
Here we investigate the temperature dependence of the low energy phonons in the
canonical CDW ordered cuprate LaBaCuO. We discover
that the phonon softening wavevector associated with CDW correlations becomes
temperature dependent in the high-temperature precursor phase and changes from
a wavevector of 0.238 reciprocal space units (r.l.u.) below the ordering
transition temperature up to 0.3~r.l.u. at 300~K. This high-temperature
behavior shows that "214"-type cuprates can host CDW correlations at a similar
wavevector to previously reported CDW correlations in non-"214"-type cuprates
such as YBaCuO. This indicates that cuprate CDWs may
arise from the same underlying instability despite their apparently different
low temperature ordering wavevectors.Comment: Accepted in Phys. Rev. X; 9 pages; 5 figures; 3 pages of
supplementary materia
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