2,214 research outputs found
Existence of anticipatory, complete and lag synchronizations in time-delay systems
Existence of different kinds of synchronizations, namely anticipatory,
complete and lag type synchronizations (both exact and approximate), are shown
to be possible in time-delay coupled piecewise linear systems. We deduce
stability condition for synchronization of such unidirectionally coupled
systems following Krasovskii-Lyapunov theory. Transition from anticipatory to
lag synchronization via complete synchronization as a function of coupling
delay is discussed. The existence of exact synchronization is preceded by a
region of approximate synchronization from desynchronized state as a function
of a system parameter, whose value determines the stability condition for
synchronization. The results are corroborated by the nature of similarity
functions. A new type of oscillating synchronization that oscillates between
anticipatory, complete and lag synchronization, is identified as a consequence
of delay time modulation with suitable stability condition.Comment: 5 Figures 9 page
Delay time modulation induced oscillating synchronization and intermittent anticipatory/lag and complete synchronizations in time-delay nonlinear dynamical systems
Existence of a new type of oscillating synchronization that oscillates
between three different types of synchronizations (anticipatory, complete and
lag synchronizations) is identified in unidirectionally coupled nonlinear
time-delay systems having two different time-delays, that is feedback delay
with a periodic delay time modulation and a constant coupling delay.
Intermittent anticipatory, intermittent lag and complete synchronizations are
shown to exist in the same system with identical delay time modulations in both
the delays. The transition from anticipatory to complete synchronization and
from complete to lag synchronization as a function of coupling delay with
suitable stability condition is discussed. The intermittent anticipatory and
lag synchronizations are characterized by the minimum of similarity functions
and the intermittent behavior is characterized by a universal asymptotic
power law distribution. It is also shown that the delay time carved
out of the trajectories of the time-delay system with periodic delay time
modulation cannot be estimated using conventional methods, thereby reducing the
possibility of decoding the message by phase space reconstruction.Comment: accepted for publication in CHAOS, revised in response to referees
comment
Phase Synchronization in Unidirectionally Coupled Ikeda Time-delay Systems
Phase synchronization in unidirectionally coupled Ikeda time-delay systems
exhibiting non-phase-coherent hyperchaotic attractors of complex topology with
highly interwoven trajectories is studied. It is shown that in this set of
coupled systems phase synchronization (PS) does exist in a range of the
coupling strength which is preceded by a transition regime (approximate PS) and
a nonsynchronous regime. However, exact generalized synchronization does not
seem to occur in the coupled Ikeda systems (for the range of parameters we have
studied) even for large coupling strength, in contrast to our earlier studies
in coupled piecewise-linear and Mackey-Glass systems
\cite{dvskml2006,dvskml2008}. The above transitions are characterized in terms
of recurrence based indices, namely generalized autocorrelation function
, correlation of probability of recurrence (CPR), joint probability of
recurrence (JPR) and similarity of probability of recurrence (SPR). The
existence of phase synchronization is also further confirmed by typical
transitions in the Lyapunov exponents of the coupled Ikeda time-delay systems
and also using the concept of localized sets.Comment: 10 pages, 7 figure
Transition from anticipatory to lag synchronization via complete synchronization in time-delay systems
The existence of anticipatory, complete and lag synchronization in a single
system having two different time-delays, that is feedback delay and
coupling delay , is identified. The transition from anticipatory to
complete synchronization and from complete to lag synchronization as a function
of coupling delay with suitable stability condition is discussed. The
existence of anticipatory and lag synchronization is characterized both by the
minimum of similarity function and the transition from on-off intermittency to
periodic structure in laminar phase distribution.Comment: 14 Pages and 12 Figure
Bubbling route to strange nonchaotic attractor in a nonlinear series LCR circuit with a nonsinusoidal force
We identify a novel route to the birth of a strange nonchaotic attractor
(SNA) in a quasiperiodically forced electronic circuit with a nonsinusoidal
(square wave) force as one of the quasiperiodic forces through numerical and
experimental studies. We find that bubbles appear in the strands of the
quasiperiodic attractor due to the instability induced by the additional square
wave type force. The bubbles then enlarge and get increasingly wrinkled as a
function of the control parameter. Finally, the bubbles get extremely wrinkled
(while the remaining parts of the strands of the torus remain largely
unaffected) resulting in the birth of the SNA which we term as the
\emph{bubbling route to SNA}. We characterize and confirm this birth from both
experimental and numerical data by maximal Lyapunov exponents and their
variance, Poincar\'e maps, Fourier amplitude spectra and spectral distribution
function. We also strongly confirm the birth of SNA via the bubbling route by
the distribution of the finite-time Lyapunov exponents.Comment: 11 pages. 11 figures, Accepted for publication in Phys. Rev.
Global generalized synchronization in networks of different time-delay systems
We show that global generalized synchronization (GS) exists in structurally
different time-delay systems, even with different orders, with quite different
fractal (Kaplan-Yorke) dimensions, which emerges via partial GS in
symmetrically coupled regular networks. We find that there exists a smooth
transformation in such systems, which maps them to a common GS manifold as
corroborated by their maximal transverse Lyapunov exponent. In addition, an
analytical stability condition using the Krasvoskii-Lyapunov theory is deduced.
This phenomenon of GS in strongly distinct systems opens a new way for an
effective control of pathological synchronous activity by means of extremely
small perturbations to appropriate variables in the synchronization manifold.Comment: 6 pages, 4 figures, Accepted for publication in Europhys. Let
A study on the Clinical Spectrum and Electrocardiographic changes in scorpion sting envenomation
INTRODUCTION:
Scorpion stings, though not a big problem in many developed countries, it is a major public health problem in underdeveloped and in some developing countries all over the world. In India, many people are stung by the red scorpion (Mesobuthus tamulus) with recorded fatalities in both adults and children. Scorpion sting is considered as a life threatening medical emergency of
villagers in India. Numerous envenomations go unreported. Hence, true incidence is frequently unavailable. Among the eighty six scorpion species in India, Mesobuthus tamulus and Palamneus swammwe-dami are of medical importance.
AIMS AND OBJECTIVES:
To study the clinical spectrum and electrocardiographic changes in scorpion sting envenomation.
Study design: Prospective study.
METHODOLOGY:
53 patients of scorpion sting envenomation who were admitted in thanjavur medical college and hospital were included in the study. The clinical spectrum, symptoms, signs, electrocardiogram, random blood glucose, complete hemogram, CK-MB were collected and analysed.
RESULTS:
53 patients were included in the study out of which 30 were male and 23 were female. There was no significant difference in clinical presentation with respect to age group and gender. Hand was the commonest site of sting. Local pain was the most common symptom followed by local swelling, paaresthesias and redness. Tenderness at the sting site was the most common sign followed by tachycardia. Pulmonary edema was present in 3 patients.18 patients had grade 3
envenomation and all those 18 patients had significant ECG changes and serum CK-MB was elevated in all these 18 patients .Sinus tachycardia was the most common ECG abnormality.
CONCLUSION:
In this study eighteen out of 53 cases had ECG changes. Three of the patients presented with pulmonary edema. There was no mortality due to scorpion sting n the study period. There was significant correlation between the time delay and severity of envenomation. This indicates a need for immediate medical care following scorpion sting Following this study it is seen that patients were stung by the scorpions due to their lack of knowledge about scorpions and due to their carelessness, like putting their hands in to scorpion homes. Follow up studies are required to assess the long term complications of scorpion stings
- …