3,879 research outputs found
Antiphase dynamics in a multimode semiconductor laser with optical injection
A detailed experimental study of antiphase dynamics in a two-mode
semiconductor laser with optical injection is presented. The device is a
specially designed Fabry-Perot laser that supports two primary modes with a THz
frequency spacing. Injection in one of the primary modes of the device leads to
a rich variety of single and two-mode dynamical scenarios, which are reproduced
with remarkable accuracy by a four dimensional rate equation model. Numerical
bifurcation analysis reveals the importance of torus bifurcations in mediating
transitions to antiphase dynamics and of saddle-node of limit cycle
bifurcations in switching of the dynamics between single and two-mode regimes.Comment: 7 pages, 9 figure
Triggering rogue waves in opposing currents
We show that rogue waves can be triggered naturally when a stable wave train
enters a region of an opposing current flow. We demonstrate that the maximum
amplitude of the rogue wave depends on the ratio between the current velocity,
, and the wave group velocity, . We also reveal that an opposing
current can force the development of rogue waves in random wave fields,
resulting in a substantial change of the statistical properties of the surface
elevation. The present results can be directly adopted in any field of physics
in which the focusing Nonlinear Schrodinger equation with non constant
coefficient is applicable. In particular, nonlinear optics laboratory
experiments are natural candidates for verifying experimentally our results.Comment: 5 pages, 5 figure
B\"{a}cklund transformations for high-order constrained flows of the AKNS hierarchy: canonicity and spectrality property
New infinite number of one- and two-point B\"{a}cklund transformations (BTs)
with explicit expressions are constructed for the high-order constrained flows
of the AKNS hierarchy. It is shown that these BTs are canonical transformations
including B\"{a}cklund parameter and a spectrality property holds with
respect to and the 'conjugated' variable for which the point
belongs to the spectral curve. Also the formulas of m-times
repeated Darboux transformations for the high-order constrained flows of the
AKNS hierarchy are presented.Comment: 21 pages, Latex, to be published in J. Phys.
Nonstoichiometric doping and Bi antisite defect in single crystal Bi2Se3
We studied the defects of Bi2Se3 generated from Bridgman growth of
stoichiometric and nonstoichiometric self-fluxes. Growth habit, lattice size,
and transport properties are strongly affected by the types of defect
generated. Major defect types of Bi_Se antisite and partial Bi_2-layer
intercalation are identified through combined studies of direct atomic-scale
imaging with scanning transmission electron microscopy (STEM) in conjunction
with energy-dispersive X-ray spectroscopy (STEM-EDX), X-ray diffraction, and
Hall effect measurements. We propose a consistent explanation to the origin of
defect type, growth morphology, and transport property.Comment: 5 pages, 5 figure
Critical behavior and synchronization of discrete stochastic phase coupled oscillators
Synchronization of stochastic phase-coupled oscillators is known to occur but
difficult to characterize because sufficiently complete analytic work is not
yet within our reach, and thorough numerical description usually defies all
resources. We present a discrete model that is sufficiently simple to be
characterized in meaningful detail. In the mean field limit, the model exhibits
a supercritical Hopf bifurcation and global oscillatory behavior as coupling
crosses a critical value. When coupling between units is strictly local, the
model undergoes a continuous phase transition which we characterize numerically
using finite-size scaling analysis. In particular, we explicitly rule out
multistability and show that that the onset of global synchrony is marked by
signatures of the XY universality class. Our numerical results cover dimensions
d=2, 3, 4, and 5 and lead to the appropriate XY classical exponents \beta and
\nu, a lower critical dimension d_{lc} = 2, and an upper critical dimension
d_{uc}=4
Bifurcation analysis of the behavior of partially wetting liquids on a rotating cylinder
We discuss the behavior of partially wetting liquids on a rotating cylinder
using a model that takes into account the effects of gravity, viscosity,
rotation, surface tension and wettability. Such a system can be considered as a
prototype for many other systems where the interplay of spatial heterogeneity
and a lateral driving force in the proximity of a first- or second-order phase
transition results in intricate behavior. So does a partially wetting drop on a
rotating cylinder undergo a depinning transition as the rotation speed is
increased, whereas for ideally wetting liquids the behavior \bfuwe{only changes
quantitatively. We analyze the bifurcations that occur when the rotation speed
is increased for several values of the equilibrium contact angle of the
partially wetting liquids. This allows us to discuss how the entire bifurcation
structure and the flow behavior it encodes changes with changing wettability.
We employ various numerical continuation techniques that allow us to track
stable/unstable steady and time-periodic film and drop thickness profiles. We
support our findings by time-dependent numerical simulations and asymptotic
analyses of steady and time-periodic profiles for large rotation numbers
Russian Manufacturing Revisited: Industrial Enterprises at the Start of the Crisis
The paper is based on the findings of a major project by the Higher School of Economics Institute for
Industrial and Market Studies (IIMS) to monitor competitiveness of manufacturing enterprises. The
study focuses on the drivers and dynamics of business competitiveness, including changes in firms’
behavior during the period before the crisis (2005-2008). The primary issue was to find out what firms
and to what extent succeeded in capitalizing on the strong economic growth before the crisis to catch
up with their competitors and gain a sustainable competitive position in the market. What was driving
output increases and enhanced production efficiency? What were the impediments to this process
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