62,104 research outputs found
Controlling the Size of Popcorn
We present a thermo-statistical model of popcorn production and propose a way
to control the final size of the popcorn by monitoring only the chamber
pressure.Comment: 6 pages; revision (typo and minor content corrections
Density Functional Theory of Hard Sphere Condensation Under Gravity
The onset of condensation of hard spheres in a gravitational field is studied
using density functional theory. In particular, we find that the local density
approximation yields results identical to those obtained previously using the
kinetic theory [Physica A 271, 192, (1999)], and a weighted density functional
theory gives qualitatively similar results, namely, that the temperature at
which condensation begins at the bottom scales linearly with weight, diameter,
and number of layers of particles.Comment: 17 pages, 4 figure
Neutron Removal from the Deformed Halo 31Ne Nucleus
Experimental data on Coulomb breakup and neutron removal indicate that 31Ne
is one of the heaviest halo nuclei discovered so far. The possible ground state
of 31Ne is either 3/2- coming from p-wave halo or 1/2+ from s-wave halo. In
this work, we develop a treatable model to include deformed wave functions and
a dynamical knockout formalism which includes the dependence on the nuclear
orientation to study the neutron removal from 31Ne projectiles at energies
around E=200 MeV/nucleon. A detailed account of the effects of deformation on
cross sections and longitudinal momentum distributions is made. Our numerical
analysis indicates a preference for the 31Ne ground state with spin parity
3/2-.Comment: 22 pages, 13 figures, accepted for publication in the Physical Review
Electro-optic scanning of light coupled from a corrugated LiNbO3 waveguide
Light diffracted from a grating output coupler in a Ti-diffused LiNbO3 waveguide is scanned electro-optically. Using a coupling length of 2.5 mm in our arrangement we have demonstrated a scanning capability of one resolved spot per 3 V/µm applied field
Broad-band grating filters for thin-film optical waveguides
Broad-band grating filters have been fabricated on glass thin-film waveguides and evaluated with a tunable dye laser. Measured and calculated filter responses were found to be in good agreement. Grating filters with bandwidths of 300 and 150 Å, and reflectivities of 18 and 40%, respectively, are reported
Provable Deterministic Leverage Score Sampling
We explain theoretically a curious empirical phenomenon: "Approximating a
matrix by deterministically selecting a subset of its columns with the
corresponding largest leverage scores results in a good low-rank matrix
surrogate". To obtain provable guarantees, previous work requires randomized
sampling of the columns with probabilities proportional to their leverage
scores.
In this work, we provide a novel theoretical analysis of deterministic
leverage score sampling. We show that such deterministic sampling can be
provably as accurate as its randomized counterparts, if the leverage scores
follow a moderately steep power-law decay. We support this power-law assumption
by providing empirical evidence that such decay laws are abundant in real-world
data sets. We then demonstrate empirically the performance of deterministic
leverage score sampling, which many times matches or outperforms the
state-of-the-art techniques.Comment: 20th ACM SIGKDD Conference on Knowledge Discovery and Data Minin
Localization in an Inhomogeneous Quantum Wire
We study interaction-induced localization of electrons in an inhomogeneous
quasi-one-dimensional system--a wire with two regions, one at low density and
the other high. Quantum Monte Carlo techniques are used to treat the strong
Coulomb interactions in the low density region, where localization of electrons
occurs. The nature of the transition from high to low density depends on the
density gradient--if it is steep, a barrier develops between the two regions,
causing Coulomb blockade effects. Ferromagnetic spin polarization does not
appear for any parameters studied. The picture emerging here is in good
agreement with measurements of tunneling between two wires.Comment: 4 pages; 2 new figures, substantial revisions and clarification
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