18,465 research outputs found
Some Measured Characteristics of Severe Storm Turbulence
Measurements of atmospheric turbulence obtained from airplane flights through severe storms in connection with the National Severe Storms Project will be discussed. Various characteristics of turbulence, such as differences in intensity between storms and the turbulence intensity with altitude and time will be indicated. These measurements for severe storm conditions will also be compared with other measurements for clear-air and non-storm weather conditions as a means of illustrating the relative severity of turbulence for various flight conditions. For these purposes, both derived gust velocities and power spectra of atmospheric turbulence will be used. The detailed nature of the vertical and horizontal flow patterns and the variations in atmospheric pressure as measured during several airplane traverses through storm centers will also be discussed
Power spectral measurement of atmospheric turbulence in severe storms and cumulus clouds
Power spectrum measurements of atmospheric turbulence in severe storms and cumulus cloud
The effect of magnetic dipolar interactions on the interchain spin wave dispersion in CsNiF_3
Inelastic neutron scattering measurements were performed on the ferromagnetic
chain system CsNiF_3 in the collinear antiferromagnetic ordered state below T_N
= 2.67K. The measured spin wave dispersion was found to be in good agreement
with linear spin wave theory including dipolar interactions. The additional
dipole tensor in the Hamiltonian was essential to explain some striking
phenomena in the measured spin wave spectrum: a peculiar feature of the
dispersion relation is a jump at the zone center, caused by strong dipolar
interactions in this system. The interchain exchange coupling constant and the
planar anisotropy energy were determined within the present model to be J'/k_B
= -0.0247(12)K and A/k_B = 3.3(1)K. This gives a ratio J/J' \approx 500, using
the previously determined intrachain coupling constant J/k_B = 11.8$. The small
exchange energy J' is of the same order as the dipolar energy, which implies a
strong competition between the both interactions.Comment: 18 pages, TeX type, 7 Postscript figures included. To be published in
Phys. Rev.
An annotated checklist of the Coleoptera (Insecta) of the Cayman Islands, West Indies
A faunal list of 605 species of Coleoptera in 396 genera in 63 families is presented for the Cayman Islands. For most species, island and locality within island collecting information is provided
Near-surface stellar magneto-convection: simulations for the Sun and a metal-poor solar analog
We present 2D local box simulations of near-surface radiative
magneto-convection with prescribed magnetic flux, carried out with the MHD
version of the CO5BOLD code for the Sun and a solar-like star with a metal-poor
chemical composition (metal abundances reduced by a factor 100, [M/H]=-2). The
resulting magneto-hydrodynamical models can be used to study the influence of
the metallicity on the properties of magnetized stellar atmospheres. A
preliminary analysis indicates that the horizontal magnetic field component
tends to be significantly stronger in the optically thin layers of metal-poor
stellar atmospheres.Comment: Proc. IAU Symposium 259, Cosmic Magnetic Fields: from Planets, to
Stars and Galaxies, K.G. Strassmeier, A.G. Kosovichev and J.E. Beckman, eds.
(2009) p.23
Δ2,10-Phytodienol as esterifying alcohol of bacteriochlorophyll b from Ectothiorhodospira halochloris
A Probabilistic Analysis of Kademlia Networks
Kademlia is currently the most widely used searching algorithm in P2P
(peer-to-peer) networks. This work studies an essential question about Kademlia
from a mathematical perspective: how long does it take to locate a node in the
network? To answer it, we introduce a random graph K and study how many steps
are needed to locate a given vertex in K using Kademlia's algorithm, which we
call the routing time. Two slightly different versions of K are studied. In the
first one, vertices of K are labelled with fixed IDs. In the second one,
vertices are assumed to have randomly selected IDs. In both cases, we show that
the routing time is about c*log(n), where n is the number of nodes in the
network and c is an explicitly described constant.Comment: ISAAC 201
Numerical computation of Maass waveforms and an application to cosmology
We compute numerically eigenvalues and eigenfunctions of the Laplacian in a
three-dimensional hyperbolic space. Applying the results to cosmology, we
demonstrate that the methods learned in quantum chaos can be used in other
fields of research.Comment: A version of the paper with high resolution figures is available at
http://www.physik.uni-ulm.de/theo/qc/publications.htm
Categorification of persistent homology
We redevelop persistent homology (topological persistence) from a categorical
point of view. The main objects of study are diagrams, indexed by the poset of
real numbers, in some target category. The set of such diagrams has an
interleaving distance, which we show generalizes the previously-studied
bottleneck distance. To illustrate the utility of this approach, we greatly
generalize previous stability results for persistence, extended persistence,
and kernel, image and cokernel persistence. We give a natural construction of a
category of interleavings of these diagrams, and show that if the target
category is abelian, so is this category of interleavings.Comment: 27 pages, v3: minor changes, to appear in Discrete & Computational
Geometr
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