1,695 research outputs found
Use of ERTS-1 data to access and monitor change in the west side of the San Joaquin Valley and central coastal zone of California
There are no author-identified significant results in this report
Model of correlated sequential adsorption of colloidal particles
We present results of a new model of sequential adsorption in which the
adsorbing particles are correlated with the particles attached to the
substrate. The strength of the correlations is measured by a tunable parameter
. The model interpolates between free ballistic adsorption in the limit
and a strongly correlated phase, appearing for
and characterized by the emergence of highly ordered structures. The phenomenon
is manifested through the analysis of several magnitudes, as the jamming limit
and the particle-particle correlation function. The effect of correlations in
one dimension manifests in the increased tendency to particle chaining in the
substrate. In two dimensions the correlations induce a percolation transition,
in which a spanning cluster of connected particles appears at a certain
critical value . Our study could be applicable to more general
situations in which the coupling between correlations and disorder is relevant,
as for example, in the presence of strong interparticle interactions.Comment: 6 pages, 8 EPS figures. Phys. Rev. E (in press
Dynamics of Phononic Dissipation at the Atomic Scale: Dependence on Internal Degrees of Freedom
Dynamics of dissipation of a local phonon distribution to the substrate is a
key issue in friction between sliding surfaces as well as in boundary
lubrication. We consider a model system consisting of an excited nano-particle
which is weakly coupled with a substrate. Using three different methods we
solve the dynamics of energy dissipation for different types of coupling
between the nano-particle and the substrate, where different types of
dimensionality and phonon densities of states were also considered for the
substrate. In this paper, we present our analysis of transient properties of
energy dissipation via phonon discharge in the microscopic level towards the
substrate. Our theoretical analysis can be extended to treat realistic
lubricant molecules or asperities, and also substrates with more complex
densities of states. We found that the decay rate of the nano-particle phonons
increases as the square of the interaction constant in the harmonic
approximation.Comment: 10 pages, 6 figures, submitted to Phys. Rev.
Evidence for Different Freeze-Out Radii of High- and Low-Energy Pions Emitted in Au+Au Collisions at 1 GeV/nucleon
Double differential production cross sections of negative and positive pions
and the number of participating protons have been measured in central Au+Au
collisions at 1 GeV per nucleon incident energy. At low pion energies the pi^-
yield is strongly enhanced over the pi^+ yield. The energy dependence of the
pi^-/pi^+ ratio is assigned to the Coulomb interaction of the charged pions
with the protons in the reaction zone. The deduced Coulomb potential increases
with increasing pion c.m. energy. This behavior indicates different freeze-out
radii for different pion energies in the c.m.~frame.Comment: IKDA is the Institute for Nuclear Physics in Darmstadt/German
On the experimental determination of the one-way speed of light
In this contribution the question of the isotropy of the one-way speed of
light from an experimental perspective is addressed. In particular, we analyze
two experimental methods commonly used in its determination. The analysis is
aimed at clarifying the view that the one-way speed of light cannot be
determined by techniques in which physical entities close paths. The procedure
employed here will provide epistemological tools such that physicists
understand that a direct measurement of the speed not only of light but of any
physical entity is by no means trivial. Our results shed light on the physics
behind the experiments which may be of interest for both physicists with an
elemental knowledge in special relativity and philosophers of science.Comment: 8 pages, 5 figures. To appear in the European Journal of Physic
Heavy quark(onium) at LHC: the statistical hadronization case
We discuss the production of charmonium in nuclear collisions within the
framework of the statistical hadronization model. We demonstrate that the model
reproduces very well the availble data at RHIC. We provide predictions for the
LHC energy where, dependently on the charm production cross section, a
dramatically different behaviour of charmonium production as a function of
centrality might be expected. We discuss also the case in elementary
collisions, where clearly the statistical model does not reproduce the
measurements.Comment: 8 pages, 5 figures; proceeding of SQM09, Buzios, Brazil, to be
published in J. Phys.
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