5,644 research outputs found
Non-equilibrium interfaces in colloidal fluids
The time-dependent structure, interfacial tension, and evaporation of an
oversaturated colloid-rich (liquid) phase in contact with an undersaturated
colloid-poor (vapor) phase of a colloidal dispersion is investigated
theoretically during the early-stage relaxation, where the interface is
relaxing towards a local equilibrium state while the bulk phases are still out
of equilibrium. Since systems of this type exhibit a clear separation of
colloidal and solvent relaxation time scales with typical times of interfacial
tension measurements in between, they can be expected to be suitable for
analogous experimental studies, too. The major finding is that, irrespective of
how much the bulk phases differ from two-phase coexistence, the interfacial
structure and the interfacial tension approach those at two-phase coexistence
during the early-stage relaxation process. This is a surprising observation
since it implies that the relaxation towards global equilibrium of the
interface is not following but preceding that of the bulk phases. Scaling forms
for the local chemical potential, the flux, and the dissipation rate exhibit
qualitatively different leading order contributions depending on whether an
equilibrium or a non-equilibrium system is considered. The degree of
non-equilibrium between the bulk phases is found to not influence the
qualitative relaxation behavior (i.e., the values of power-law exponents), but
to determine the quantitative deviation of the observed quantities from their
values at two-phase coexistence. Whereas the underlying dynamics differs
between colloidal and molecular fluids, the behavior of quantities such as the
interfacial tension approaching the equilibrium values during the early-stage
relaxation process, during which non-equilibrium conditions of the bulk phases
are not changed, can be expected to occur for both types of systems.Comment: Submitte
Multivariate sparse interpolation using randomized Kronecker substitutions
We present new techniques for reducing a multivariate sparse polynomial to a
univariate polynomial. The reduction works similarly to the classical and
widely-used Kronecker substitution, except that we choose the degrees randomly
based on the number of nonzero terms in the multivariate polynomial, that is,
its sparsity. The resulting univariate polynomial often has a significantly
lower degree than the Kronecker substitution polynomial, at the expense of a
small number of term collisions. As an application, we give a new algorithm for
multivariate interpolation which uses these new techniques along with any
existing univariate interpolation algorithm.Comment: 21 pages, 2 tables, 1 procedure. Accepted to ISSAC 201
Laboratory studies of atomic oxygen reactions with solids
Atomic beam experiments were performed to investigate the rate of atomic oxygen etching of carbon and polyimide films. The main emphasis of these experiments was on gaining an understanding of the role of atomic oxygen translational energy and substrate temperature in promoting the reactions. The experimental facility and techniques are described and results reviewed
One-Loop Calculations and Detailed Analysis of the Localized Non-Commutative 1/p**2 U(1) Gauge Model
This paper carries forward a series of articles describing our enterprise to
construct a gauge equivalent for the -deformed non-commutative
model originally introduced by Gurau et al. arXiv:0802.0791. It is shown that
breaking terms of the form used by Vilar et al. arXiv:0902.2956 and ourselves
arXiv:0901.1681 to localize the BRST covariant operator
lead to difficulties concerning renormalization. The reason is that this
dimensionless operator is invariant with respect to any symmetry of the model,
and can be inserted to arbitrary power. In the present article we discuss
explicit one-loop calculations, and analyze the mechanism the mentioned
problems originate from.Comment: v2: minor corrections and references added; v3: published versio
April: A Song Cycle for Low Voice and Chamber Orchestra
An original composition in five movements for voice and a chamber orchestra of eleven instruments. The first movement is an overture; the second and fifth movements have text by Sara Teasdale; the third and fourth movements have text by Edna St. Vincent Millay
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