28,558 research outputs found
Assessing the effectiveness of pen-based input queries
In this poster, we describe an experiment exploring the effectiveness of a pen based text input device for use in query construction. Standard TREC queries were written, recognised, and subsequently retrieved upon. Comparisons between retrieval effectiveness based on the recognised writing and a typed text baseline were made. On average, effectiveness was 75% of the baseline. Other statistics on the quality and nature of recognition are also reported
Monopole solutions to the Bogomolny equation as three-dimensional generalizations of the Kronecker series
The Dirac monopole on a three-dimensional torus is considered as a solution
to the Bogomolny equation with non-trivial boundary conditions. The analytical
continuation of the obtained solution is shown to be a three-dimensional
generalization of the Kronecker series. It satisfies the corresponding
functional equation and is invariant under modular transformations.Comment: 13 pages, 1 figur
Electrolytes between dielectric charged surfaces: Simulations and theory
We present a simulation method to study electrolyte solutions in a dielectric
slab geometry using a modified 3D Ewald summation. The method is fast and easy
to implement, allowing us to rapidly resum an infinite series of image charges.
In the weak coupling limit, we also develop a mean-field theory which allows us
to predict the ionic distribution between the dielectric charged plates. The
agreement between both approaches, theoretical and simulational, is very good,
validating both methods. Examples of ionic density profiles in the strong
electrostatic coupling limit are also presented. Finally, we explore the
confinement of charge asymmetric electrolytes between neutral surfaces
Kinetic Inflation in Stringy and Other Cosmologies
An inflationary epoch driven by the kinetic energy density in a dynamical
Planck mass is studied. In the conformally related Einstein frame it is easiest
to see the demands of successful inflation cannot be satisfied by kinetic
inflation alone. Viewed in the original Jordan-Brans-Dicke frame, the obstacle
is manifest as a kind of graceful exit problem and/or a kind of flatness
problem. These arguments indicate the weakness of only the simplest
formulation. {}From them can be gleaned directions toward successful kinetic
inflation.Comment: 26 pages, LaTeX, CITA-94-2
Distinguishing Marks of Simply-connected Universes
A statistical quantity suitable for distinguishing simply-connected
Robertson-Walker (RW) universes is introduced, and its explicit expressions for
the three possible classes of simply-connected RW universes with an uniform
distribution of matter are determined. Graphs of the distinguishing mark for
each class of RW universes are presented and analyzed.There sprout from our
results an improvement on the procedure to extract the topological signature of
multiply-connected RW universes, and a refined understanding of that
topological signature of these universes studied in previous works.Comment: 13 pages, 4 figures, LaTeX2e. To appear in Int. J. Mod. Phys. D
(2000
Production of q bar-q Pairs in Proton-Nucleus Collisions at High Energies
We calculate production of quark-antiquark pairs in high energy
proton-nucleus collisions both in the quasi-classical approximation of
McLerran-Venugopalan model and including quantum small- evolution. The
resulting production cross section is explicitly expressed in terms of
Glauber-Mueller multiple rescatterings in the classical case and in terms of
dipole-nucleus scattering amplitude in the quantum evolution case. We
generalize the result of one of us (K.T.) beyond the aligned jet
configurations. We expand on the earlier results of Blaizot, Gelis and
Venugopalan by deriving quark production cross section including quantum
evolution corrections in rapidity intervals both between the quarks and the
target and between the quarks and the projectile.Comment: 18 pages, 3 figures; typos corrected, discussion extende
Charge renormalization and phase separation in colloidal suspensions
We explore the effects of counterion condensation on fluid-fluid phase
separation in charged colloidal suspensions. It is found that formation of
double layers around the colloidal particles stabilizes suspensions against
phase separation. Addition of salt, however, produces an instability which, in
principle, can lead to a fluid-fluid separation. The instability, however, is
so weak that it should be impossible to observe a fully equilibrated
coexistence experimentally.Comment: 7 pages, Europhysics Letters (in press
A Neutral Polyampholyte in an ionic solution
The behavior of a neutral polyampholyte () chain with monomers, in an
ionic solution, is analyzed in the framework of the full Debye-Hckel-Bjerrum-Flory theory. A chain, that in addition to the
neutral monomers, also contains an equal number of positively and negatively
charged monomers, is dissolved in an ionic solution. For \underline{high}
concentrations of salt and at high temperatures, the exists in an extended
state. As the temperature is decreased, the electrostatic energy becomes more
relevant and at a the system collapses into a dilute globular
state, or microelectrolyte. This state contains a concentration of salt higher
than the surrounding medium. As the temperature is decreased even further,
association between the monomers of the polymer and the ions of the salt
becomes relevant and there is a crossover from this globular state to a low
temperature extended state. For \underline{low} densities of salt, the system
is collapsed for almost all temperatures and exhibits a first-order phase
transition to an extended state at an unphysical low temperature.Comment: 10 pages, Revtex with epsf, 9 Postscript figures. Submitted to PR
Charge reversal of colloidal particles
A theory is presented for the effective charge of colloidal particles in
suspensions containing multivalent counterions. It is shown that if colloids
are sufficiently strongly charged, the number of condensed multivalent
counterion can exceed the bare colloidal charge leading to charge reversal.
Charge renormalization in suspensions with multivalent counterions depends on a
subtle interplay between the solvation energies of the multivalent counterions
in the bulk and near the colloidal surface. We find that the effective charge
is {\it not} a monotonically decreasing function of the multivalent salt
concentration. Furthermore, contrary to the previous theories, it is found that
except at very low concentrations, monovalent salt hinders the charge reversal.
This conclusion is in agreement with the recent experiments and simulations
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