30,970 research outputs found
Origin of rebounds with a restitution coefficient larger than unity in nanocluster collisions
We numerically investigate the mechanism of super rebounds for head-on
collisions between nanoclusters in which the restitution coefficient is larger
than unity. It is confirmed that the temperature and the entropy of the
nanocluters decrease after the super rebounds by our molecular dynamics
simulations. It is also found that the initial metastable structure plays a key
role for the emergence of the super rebounds.Comment: 8 pages, 10 figures, to be published in Phys. Rev.
Substructure in clusters containing wide-angle tailed radio galaxies. I. New redshifts
We present new redshifts and positions for 635 galaxies in nine rich clusters
containing Wide-Angle Tailed (WAT) radio galaxies. Combined with existing data,
we now have a sample of 18 WAT-containing clusters with more than 10 redshifts.
This sample contains a substantial portion of the WAT clusters in the VLA 20 cm
survey of Abell clusters, including 75% of WAT clusters in the complete survey
(z0.09. It is a representative sample
which should not contain biases other than selection by radio morphology. We
graphically present the new data using histograms and sky maps. A
semi-automated procedure is used to search for emission lines in the spectra in
order to add and verify galaxy redshifts. We find that the average apparent
fraction of emission line galaxies is about 9% in both the clusters and the
field. We investigate the magnitude completeness of our redshift surveys with
CCD data for a test case, Abell 690. This case indicates that our galaxy target
lists are deeper than the detection limit of a typical MX exposure, and they
are 82% complete down to R=19.0. The importance of the uniformity of the
placement of fibers on targets is posited, and we evaluate this in our
datasets. We find some cases of non-uniformities which may influence dynamical
analyses. A second paper will use this database to look for correlations
between the WAT radio morphology and the cluster's dynamical state.Comment: 15 pages, 5 figures, 7 tables. To appear in the Astronomical Journa
Comment on 'Non-equilibrium thermodynamics of light absorption'
A recent paper by Meszéna and Westerhoff (1999 J. Phys. A: Math. Gen. 32 301) has aimed to address what is referred to as a principal question of biological thermodynamics, the possibility of describing photosynthesis in terms of non-equilibrium thermodynamics. The issue is associated with a misrepresentation of the fundamental photophysics involved, and as a result the analysis is invalid
Dynamics of axial separation in long rotating drums
We propose a continuum description for the axial separation of granular
materials in a long rotating drum. The model, operating with two local
variables, concentration difference and the dynamic angle of repose, describes
both initial transient traveling wave dynamics and long-term segregation of the
binary mixture. Segregation proceeds through ultra-slow logarithmic coarsening.Comment: 4 pages, 3 Postscript figures; submitted to PR
Optimal rotations of deformable bodies and orbits in magnetic fields
Deformations can induce rotation with zero angular momentum where dissipation
is a natural ``cost function''. This gives rise to an optimization problem of
finding the most effective rotation with zero angular momentum. For certain
plastic and viscous media in two dimensions the optimal path is the orbit of a
charged particle on a surface of constant negative curvature with magnetic
field whose total flux is half a quantum unit.Comment: 4 pages revtex, 4 figures + animation in multiframe GIF forma
Electric field inversion asymmetry: Rashba and Stark effects for holes in resonant tunneling devices
We report experimental evidence of excitonic spin-splitting, in addition to
the conventional Zeeman effect, produced by a combination of the Rashba
spin-orbit interaction, Stark shift and charge screening. The
electric-field-induced modulation of the spin-splitting are studied during the
charging and discharging processes of p-type GaAs/AlAs double barrier resonant
tunneling diodes (RTD) under applied bias and magnetic field. The abrupt
changes in the photoluminescence, with the applied bias, provide information of
the charge accumulation effects on the device.Comment: 4 pages, 2 figure
Organizational adaption to changes in public objectives for management of Cache La Poudre River system
Research Period: 1965-1969.June 30, 1969.Submitted to Office of Water Resources Research, U.S. Department of Interior.Project A-005-COLO, Grant agreement no. 14-01-0001-1625
Association Between Measures of Body Composition and Functional Movement in Cancer Survivors
poste
Li-rich RGB stars in the Galactic Bulge
We present Lithium abundance determination for a sample of K giant stars in
the galactic bulge. The stars presented here are the only 13 stars with
detectable Lithium line (6767.18 A) among ~400 stars for which we have spectra
in this wavelength range, half of them in Baade's Window (b=-4) and half in a
field at b=-6. The stars were observed with the GIRAFFE spectrograph of
FLAMES@VLT, with a spectral resolution of R~20,000. Abundances were derived via
spectral synthesis and the results are compared with those for stars with
similar parameters, but no detectable Li line. We find 13 stars with a
detectable Li line, among which 2 have abundances A(Li)>2.7. No clear
correlations were found between the Li abundance and those of other elements.
With the exception of the two most Li rich stars, the others follow a fairly
tight A(Li)-T_eff correlation. It would seems that there must be a Li
production phase during the red giant branch (RGB), acting either on a very
short timescale, or selectively only in some stars. The proposed Li production
phase associated with the RGB bump cannot be excluded, although our targets are
significantly brighter than the predicted RGB bump magnitude for a population
at 8 kpcComment: 8 pages, 9 figures, accepted for publication in A&
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