9,412 research outputs found
Mathematical model for predicting human vertebral fracture
Mathematical model has been constructed to predict dynamic response of tapered, curved beam columns in as much as human spine closely resembles this form. Model takes into consideration effects of impact force, mass distribution, and material properties. Solutions were verified by dynamic tests on curved, tapered, elastic polyethylene beam
Transition to Reconstructibility in Weakly Coupled Networks
Across scientific disciplines, thresholded pairwise measures of statistical
dependence between time series are taken as proxies for the interactions
between the dynamical units of a network. Yet such correlation measures often
fail to reflect the underlying physical interactions accurately. Here we
systematically study the problem of reconstructing direct physical interaction
networks from thresholding correlations. We explicate how local common cause
and relay structures, heterogeneous in-degrees and non-local structural
properties of the network generally hinder reconstructibility. However, in the
limit of weak coupling strengths we prove that stationary systems with dynamics
close to a given operating point transition to universal reconstructiblity
across all network topologies.Comment: 15 pages, 4 figures, supplementary material include
Generating Generalized Distributions from Dynamical Simulation
We present a general molecular-dynamics simulation scheme, based on the Nose'
thermostat, for sampling according to arbitrary phase space distributions. We
formulate numerical methods based on both Nose'-Hoover and Nose'-Poincare'
thermostats for two specific classes of distributions; namely, those that are
functions of the system Hamiltonian and those for which position and momentum
are statistically independent. As an example, we propose a generalized variable
temperature distribution that designed to accelerate sampling in molecular
systems.Comment: 10 pages, 3 figure
Plateau Inflation from Random Non-Minimal Coupling
A generic non-minimal coupling can push any higher-order terms of the scalar
potential sufficiently far out in field space to yield observationally viable
plateau inflation. We provide analytic and numerical evidence that this
generically happens for a non-minimal coupling strength of the order
. In this regime, the non-minimally coupled field is sub-Planckian
during inflation and is thus protected from most higher-order terms. For larger
values of , the inflationary predictions converge towards the sweet spot
of PLANCK. The latter includes obtained from CMB normalization
arguments, thus providing a natural explanation for the inflationary
observables measured.Comment: 9 pages, twocolumn, some figures; v2: 1 figure and appendix added,
jcap layou
Bogoliubov excitation spectrum of an elongated condensate from quasi-one-dimensional to three-dimensional transition
The quasiparticle excitation spectra of a Bose gas trapped in a highly
anisotropic trap is studied with respect to varying total number of particles
by numerically solving the effective one-dimensional (1D) Gross-Pitaevskii (GP)
equation proposed recently by Mateo \textit{et al.}. We obtain the static
properties and Bogoliubov spectra of the system in the high energy domain. This
method is computationally efficient and highly accurate for a condensate system
undergoing a 1D to three-dimensional (3D) cigar-shaped transition, as is shown
through a comparison our results with both those calculated by the 3D-GP
equation and analytical results obtained in limiting cases. We identify the
applicable parameter space for the effective 1D-GP equation and find that this
equation fails to describe a system with large number of atoms. We also
identify that the description of the transition from 1D Bose-Einstein
condensate (BEC) to 3D cigar-shaped BEC using this equation is not smooth,
which highlights the fact that for a finite value of the junction
between the 1D and 3D crossover is not perfect.Comment: 17 pages, 6 figure
A Revised Textual Tree Trace Notation for Prolog
This paper describes a ''textual tree trace'' (TTT) notation for representing the execution of Prolog programs. Compact, textual and non-linear, it provides detailed information about variable binding and execution history, and distinguishes several modes of goal failure. The revised form given here, yet to be empirically tested, is partly informed by Paul Mulholland's empirical comparisons of Prolog trace notations, in which an earlier version of the TTT notation was amongst those studied and criticised. The work presented here is an updated version of a previous workshop paper (Taylor, du Boulay, & Patel, 1994)
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