122,602 research outputs found
The Gentlest Ascent Dynamics
Dynamical systems that describe the escape from the basins of attraction of
stable invariant sets are presented and analyzed. It is shown that the stable
fixed points of such dynamical systems are the index-1 saddle points.
Generalizations to high index saddle points are discussed. Both gradient and
non-gradient systems are considered. Preliminary results on the nature of the
dynamical behavior are presented
Spin-one bosons in low dimensional Mott insulating states
We analyze the strong coupling limit of spin-one bosons in low dimensional
Mott insulating states. In 1D lattices, for an odd number of bosons per site
(), the ground state is a dimerized valence bond crystal state with a
two-fold degeneracy; the low lying elementary spin excitations carry spin one.
For an even number of bosons per site, the ground state is a nondegenerate spin
singlet Mott state. We also argue that in a square lattice in a quantum
disordered limit the ground states should be dimerized valence bond crystals
for an odd integer . Finally, we briefly report results for non-integer
numbers of bosons per site in one-dimensional lattices.Comment: 5 pages; discussions on non-integer case have been shortene
Nearly Scale-Invariant Spectrum of Adiabatic Fluctuations May be from a Very Slowly Expanding Phase of the Universe
In this paper we construct an expanding phase with phantom matter, in which
the scale factor expands very slowly but the Hubble parameter increases
gradually, and assume that this expanding phase could be matched to our late
observational cosmology by the proper mechanism. We obtain the nearly
scale-invariant spectrum of adiabatic fluctuations in this scenario, different
from the simplest inflation and usual ekpyrotic/cyclic scenario, the tilt of
nearly scale-invariant spectrum in this scenario is blue. Although there exists
an uncertainty surrounding the way in which the perturbations propagate through
the transition in our scenario, which is dependent on the detail of possible
"bounce" physics, compared with inflation and ekpyrotic/cyclic scenario, our
work may provide another feasible cosmological scenario generating the nearly
scale-invariant perturbation spectrum.Comment: 4 pages, no figures, to appear in Phys. Rev. D. Many thanks for
referee's kind comments and criticism
Is there a global model of learning organizations? An empirical, cross-nation study
This paper develops and tests a learning organization model derived from HRM and dynamic capability literatures in order to ascertain the model’s applicability across divergent global contexts. We define a learning organization as one capable of achieving on-going strategic renewal, arguing based on dynamic capability theory that the model has three necessary antecedents: HRM focus, developmental orientation and customer-facing remit. Drawing on a sample comprising nearly 6000 organizations across 15 countries, we show that learning organizations exhibit higher performance than their less learning-inclined counterparts. We also demonstrate that innovation fully mediates the relationship between our conceptualization of the learning organization and organizational performance in 11 of the 15 countries we examined. It is the first time in our knowledge that these questions have been tested in a major, cross- global study, and our work contributes to both HRM and dynamic capability literatures, especially where the focus is the applicability of best practice parameters across national boundaries
Energy-dependent partial-wave analysis of all antiproton-proton scattering data below 925 MeV/c
We present a new energy-dependent partial-wave analysis of all
antiproton-proton elastic and charge-exchange scattering data below 925 MeV/c
antiproton laboratory momentum. The long-range parts of the chiral one- and
two-pion exchange interactions are included exactly. The short-range
interactions, including the coupling to the mesonic annihilation channels, are
parametrized by a complex boundary condition at a radius of r=1.2 fm. The
updated database, which includes significantly more high-quality
charge-exchange data, contains 3749 scattering data. The fit results in
chi^2_min/N_df=1.048, where N_df=3578 is the number of degrees of freedom. We
discuss the description of the experimental data and we present the
antiproton-proton phase-shift parameters
Universality in the synchronization of weighted random networks
Realistic networks display not only a complex topological structure, but also
a heterogeneous distribution of weights in the connection strengths. Here we
study synchronization in weighted complex networks and show that the
synchronizability of random networks with large minimum degree is determined by
two leading parameters: the mean degree and the heterogeneity of the
distribution of node's intensity, where the intensity of a node, defined as the
total strength of input connections, is a natural combination of topology and
weights. Our results provide a possibility for the control of synchronization
in complex networks by the manipulation of few parameters.Comment: 4 pages, 3 figure
Community detection in multiplex networks using locally adaptive random walks
Multiplex networks, a special type of multilayer networks, are increasingly
applied in many domains ranging from social media analytics to biology. A
common task in these applications concerns the detection of community
structures. Many existing algorithms for community detection in multiplexes
attempt to detect communities which are shared by all layers. In this article
we propose a community detection algorithm, LART (Locally Adaptive Random
Transitions), for the detection of communities that are shared by either some
or all the layers in the multiplex. The algorithm is based on a random walk on
the multiplex, and the transition probabilities defining the random walk are
allowed to depend on the local topological similarity between layers at any
given node so as to facilitate the exploration of communities across layers.
Based on this random walk, a node dissimilarity measure is derived and nodes
are clustered based on this distance in a hierarchical fashion. We present
experimental results using networks simulated under various scenarios to
showcase the performance of LART in comparison to related community detection
algorithms
Weighted networks are more synchronizable: how and why
Most real-world networks display not only a heterogeneous distribution of
degrees, but also a heterogeneous distribution of weights in the strengths of
the connections. Each of these heterogeneities alone has been shown to suppress
synchronization in random networks of dynamical systems. Here we review our
recent findings that complete synchronization is significantly enhanced and
becomes independent of both distributions when the distribution of weights is
suitably combined with the distribution of degrees. We also present new results
addressing the optimality of our findings and extending our analysis to phase
synchronization in networks of non-identical dynamical units.Comment: Proceedings of the CNET 2004 (29 August - 2 September 2004
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