6,483 research outputs found
Application of the parametrical surface-wave prediction model to rapidly varying wind fields during JONSWAP 1973
The capability of a parametrical surface wave model to predict the sea state on a small array for highly variable wind fields is shown for three examples. The model treats the wind sea, for which the nonlinear interaction is most effective, in a parametrical sense. The swell is propagated along characteristics, and the source function for the swell is assumed to be zero. The model output is compared with wave measure- ments from the JONSWAP 73 experimen
Best practices for HPM-assisted performance engineering on modern multicore processors
Many tools and libraries employ hardware performance monitoring (HPM) on
modern processors, and using this data for performance assessment and as a
starting point for code optimizations is very popular. However, such data is
only useful if it is interpreted with care, and if the right metrics are chosen
for the right purpose. We demonstrate the sensible use of hardware performance
counters in the context of a structured performance engineering approach for
applications in computational science. Typical performance patterns and their
respective metric signatures are defined, and some of them are illustrated
using case studies. Although these generic concepts do not depend on specific
tools or environments, we restrict ourselves to modern x86-based multicore
processors and use the likwid-perfctr tool under the Linux OS.Comment: 10 pages, 2 figure
Cadaveric Renal transplantation with Cyclosporine: Experiences in 148 patients at a single institution.
The QCD phase diagram from analytic continuation
We present the crossover line between the quark gluon plasma and the hadron
gas phases for small real chemical potentials. First we determine the effect of
imaginary values of the chemical potential on the transition temperature using
lattice QCD simulations. Then we use various formulas to perform an analytic
continuation to real values of the baryo-chemical potential. Our data set
maintains strangeness neutrality to match the conditions of heavy ion physics.
The systematic errors are under control up to MeV. For the
curvature of the transition line we find that there is an approximate agreement
between values from three different observables: the chiral susceptibility,
chiral condensate and strange quark susceptibility. The continuum extrapolation
is based on 10, 12 and 16 lattices. By combining the analysis for these
three observables we find, for the curvature, the value .Comment: 14 pages, 4 figures, revised versio
Gravitating Brane Systems: Some General Theorems
Multidimensional gravity interacting with intersecting electric and magnetic
-branes is considered for fields depending on a single variable. Some
general features of the system behaviour are revealed without solving the field
equations. Thus, essential asymptotic properties of isotropic cosmologies are
indicated for different signs of spatial curvature; a no-hair-type theorem and
a single-time theorem for black holes are proved (the latter makes sense in
models with multiple time coordinates). The validity of the general
observations is verified for a class of exact solutions known for the cases
when certain vectors, built from the input parameters of the model, are either
orthogonal in minisuperspace, or form mutually orthogonal subsystems. From the
non-existence of Lorentzian wormholes, a universal restriction is obtained,
applicable to orthogonal or block-orthogonal subsystems of any -brane
system.Comment: 13 pages, Latex2e, 1 Latex figure, uses bezier.st
Substrate rigidity deforms and polarizes active gels
We present a continuum model of the coupling between cells and substrate that
accounts for some of the observed substrate-stiffness dependence of cell
properties. The cell is modeled as an elastic active gel, adapting recently
developed continuum theories of active viscoelastic fluids. The coupling to the
substrate enters as a boundary condition that relates the cell's deformation
field to local stress gradients. In the presence of activity, the coupling to
the substrate yields spatially inhomogeneous contractile stresses and
deformations in the cell and can enhance polarization, breaking the cell's
front-rear symmetry.Comment: 6 pages, 4 figures, EPL forma
Bouncing inflation in nonlinear gravitational model
We study a gravitational model with curvature-squared and
curvature-quartic nonlinearities. The effective scalar degree of freedom
(scalaron) has a multi-valued potential consisting of a number
of branches. These branches are fitted with each other in the branching and
monotonic points. In the case of four-dimensional space-time, we show that the
monotonic points are penetrable for scalaron while in the vicinity of the
branching points scalaron has the bouncing behavior and cannot cross these
points. Moreover, there are branching points where scalaron bounces an infinite
number of times with decreasing amplitude and the Universe asymptotically
approaches the de Sitter stage. Such accelerating behavior we call bouncing
inflation. For this accelerating expansion there is no need for original
potential to have a minimum or to check the slow-roll conditions. A
necessary condition for such inflation is the existence of the branching
points. This is a new type of inflation. We show that bouncing inflation takes
place both in the Einstein and Brans-Dicke frames.Comment: RevTex 13 pages, 13 figures, a few comments and references adde
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