36,989 research outputs found
Transient dynamics for sequence processing neural networks: effect of degree distributions
We derive a analytic evolution equation for overlap parameters including the
effect of degree distribution on the transient dynamics of sequence processing
neural networks. In the special case of globally coupled networks, the
precisely retrieved critical loading ratio is obtained,
where is the network size. In the presence of random networks, our
theoretical predictions agree quantitatively with the numerical experiments for
delta, binomial, and power-law degree distributions.Comment: 11 pages, 6 figure
Geometric phase for nonlinear coherent and squeezed state
The geometric phases for standard coherent states which are widely used in
quantum optics have attracted a large amount of attention. Nevertheless, few
physicists consider about the counterparts of non-linear coherent states, which
are useful in the description of the motion of a trapped ion. In this paper,
the non-unitary and non-cyclic geometric phases for two nonlinear coherent and
one squeezed states are formulated respectively. Moreover, some of their common
properties are discussed respectively, such as gauge invariance, non-locality
and non-linear effects. The non-linear functions have dramatic impacts on the
evolution of the corresponding geometric phases. They speed the evolution up or
down. So this property may have application in controlling or measuring
geometric phase. For the squeezed case, when the squeezed parameter r ->
\infinity, the limiting value of the geometric phase is also determined by
non-linear function at a given time and angular velocity. In addition, the
geometric phases for standard coherent and squeezed states are obtained under a
particular condition. When the time evolution undergoes a period, their
corresponding cyclic geometric phases are achieved as well. And the distinction
between the geometric phases of the two coherent states maybe regarded as a
geometric criterion
Adiabatic Condition and Quantum Geometric Potential
In this paper, we present a U(1)-invariant expansion theory of the adiabatic
process. As its application, we propose and discuss new sufficient adiabatic
approximation conditions. In the new conditions, we find a new invariant
quantity referred as quantum geometric potential (QGP) contained in all
time-dependent processes. Furthermore, we also give detailed discussion and
analysis on the properties and effects of QGP.Comment: 5 pages, 1 figur
Structural constraints in complex networks
We present a link rewiring mechanism to produce surrogates of a network where
both the degree distribution and the rich--club connectivity are preserved. We
consider three real networks, the AS--Internet, the protein interaction and the
scientific collaboration. We show that for a given degree distribution, the
rich--club connectivity is sensitive to the degree--degree correlation, and on
the other hand the degree--degree correlation is constrained by the rich--club
connectivity. In particular, in the case of the Internet, the assortative
coefficient is always negative and a minor change in its value can reverse the
network's rich--club structure completely; while fixing the degree distribution
and the rich--club connectivity restricts the assortative coefficient to such a
narrow range, that a reasonable model of the Internet can be produced by
considering mainly the degree distribution and the rich--club connectivity. We
also comment on the suitability of using the maximal random network as a null
model to assess the rich--club connectivity in real networks.Comment: To appear in New Journal of Physics (www.njp.org
Effects of tidal-forcing variations on tidal properties along a narrow convergent estuary
A 1D analytical framework is implemented in a narrow convergent estuary that is 78 km in length (the Guadiana, Southern Iberia) to evaluate the tidal dynamics along the channel, including the effects of neap-spring amplitude variations at the mouth. The close match between the observations (damping from the mouth to ∼ 30 km, shoaling upstream) and outputs from semi-closed channel solutions indicates that the M2 tide is reflected at the estuary head. The model is used to determine the contribution of reflection to the dynamics of the propagating wave. This contribution is mainly confined to the upper one third of the estuary. The relatively constant mean wave height along the channel (< 10% variations) partly results from reflection effects that also modify significantly the wave celerity and the phase difference between tidal velocity and elevation (contradicting the definition of an “ideal” estuary). Furthermore, from the mouth to ∼ 50 km, the variable friction experienced by the incident wave at neap and spring tides produces wave shoaling and damping, respectively. As a result, the wave celerity is largest at neap tide along this lower reach, although the mean water level is highest in spring. Overall, the presented analytical framework is useful for describing the main tidal properties along estuaries considering various forcings (amplitude, period) at the estuary mouth and the proposed method could be applicable to other estuaries with small tidal amplitude to depth ratio and negligible river discharge.info:eu-repo/semantics/publishedVersio
Failure regime in (1+1) dimensions in fibrous materials
In this paper, we introduce a model for fracture in fibrous materials that
takes into account the rupture height of the fibers, in contrast with previous
models. Thus, we obtain the profile of the fracture and calculate its
roughness, defined as the variance around the mean height. We investigate the
relationship between the fracture roughness and the fracture toughness.Comment: 4 pages, 4 figures.eps, Revte
Demonstrating Additional Law of Relativistic Velocities based on Squeezed Light
Special relativity is foundation of many branches of modern physics, of which
theoretical results are far beyond our daily experience and hard to realized in
kinematic experiments. However, its outcomes could be demonstrated by making
use of convenient substitute, i.e. squeezed light in present paper. Squeezed
light is very important in the field of quantum optics and the corresponding
transformation can be regarded as the coherent state of SU(1; 1). In this
paper, the connection between the squeezed operator and Lorentz boost is built
under certain conditions. Furthermore, the additional law of relativistic
velocities and the angle of Wigner rotation are deduced as well
Searching for new physics in decays
For any new physics possibly emerging in the future B experiments, the
problem is how to extract the signals from the SM background. We consider the
decay which is very small in the SM. In the MSSM this decay is
possibly accessible in the future experiments. In the supersymmetric models
with R-parity violating couplings, this channel is not strictly constrained,
thus being useful in obtaining bounds on the lepton-number violating couplings.
A typical candidate for the suggested search is the mode.Comment: 9 pages, one figure, late
- …