101,981 research outputs found
Chemical Waves
No full textIn our paper we try to describe the basic concepts
of chemical waves and spatial pattern formation
in a simple way. We pay particular attention to self-organisation
phenomena in extended excitable systems.
These result in the appearance of travelling waves,
spiral waves, target patterns, Turing structures or more
complicated structures called scroll waves, which are
three-dimensional systems. We describe the most
famous oscillating reaction, the Belousov–Zhabotinsky
(BZ) reaction, in greater detail. This is because it is of
great interest in both physical chemistry and in studies
on the evolution and sustenance of self-organising biological
systems
A Ternary nonequilibrium phase diagram for a closed unstirred Belousov-Zhabotinsky system
No full textIn order to analyze the fields of existence of the chaotic region as a function of initial concentration in a closed unstirred cerium catalyzed Belousov-Zhabotinsky system, a large number of experiments were carried out, varying the relative quantities of the three principal reactants (malonic acid, potassium bromate and cerium(IV)). A ternary bifurcation diagram is shown as a function of the percentage in volume of the three initial concentrations of reactants. Chaotic, quasi-periodic, periodic and no oscillations regions are clearly demonstrated
Chemical Waves
No full textIn our paper we try to describe the basic concepts of chemical waves and spatial pattern formation in a simple way. We pay particular attention to self-organisation phenomena in extended excitable systems. These result in the appearance of travelling waves, spiral waves, target patterns, Turing structures or more complicated structures called scroll waves, which are three-dimensional systems. We describe the most famous oscillating reaction, the Belousov-Zhabotinsky (BZ) reaction, in greater detail. This is because it is of great interest in both physical chemistry and in studies on the evolution and sustenance of self-organising biological systems
Hyperchaotic qualities of the ball motion in a ball milling device
No full textBall collisions in milling devices are governed by complex dynamics ruled by impredictable impulsive forces. In this paper, nonlinear dynamics techniques are employed to analyze the time series describing the trajectory of a milling ball in an empty container obtained from a numerical model. The attractor underlying the system dynamics was reconstructed by the time delay method. In order to characterize the system dynamics the calculation of the spectrum of Lyapunov exponents was performed. Six Lyapunov exponents, divided into two terns with opposite sign, were obtained. The detection of the positive tern demonstrates the occurrence of the hyperchaotic qualities of the ball motion. A fractal Lyapunov dimension, equal to 5.62, was also obtained confirming the strange features of the attractor
An overground robotic exoskeleton gait training in complete spinal cord injured patients
No full textThe use of robotic systems during the rehabilitation of spinal cord injured patients can contribute to achieve significant outcomes. The aim of this study is to investigate the effects of an overground robot-assisted gait training in complete spinal cord injured patients. Sixteen SCI patients (mean age: 35.3 ± 10.3 yrs) underwent 20 robot-assisted gait training sessions based on an overground robotic exoskeleton. The preliminary results of this study show that the robot-assisted gait training in complete SCI patients can improve patient-robot interaction
An integrated gait rehabilitation training based on Functional Electrical Stimulation cycling and overground robotic exoskeleton in complete spinal cord injury patients: Preliminary results
No full textThe aim of this study is to investigate the effects of an integrated gait rehabilitation training based on Functional Electrical Stimulation (FES)-cycling and overground robotic exoskeleton in a group of seven complete spinal cord injury patients on spasticity and patient-robot interaction. They underwent a robot-assisted rehabilitation training based on two phases: n=20 sessions of FES-cycling followed by n= 20 sessions of robot-assisted gait training based on an overground robotic exoskeleton. The following clinical outcome measures were used: Modified Ashworth Scale (MAS), Numerical Rating Scale (NRS) on spasticity, Penn Spasm Frequency Scale (PSFS), Spinal Cord Independence Measure Scale (SCIM), NRS on pain and International Spinal Cord Injury Pain Data Set (ISCI). Clinical outcome measures were assessed before (T0) after (T1) the FES-cycling training and after (T2) the powered overground gait training. The ability to walk when using exoskeleton was assessed by means of 10 Meter Walk Test (10MWT), 6 Minute Walk Test (6MWT), Timed Up and Go test (TUG), standing time, walking time and number of steps. Statistically significant changes were found on the MAS score, NRS-spasticity, 6MWT, TUG, standing time and number of steps. The preliminary results of this study show that an integrated gait rehabilitation training based on FES-cycling and overground robotic exoskeleton in complete SCI patients can provide a significant reduction of spasticity and improvements in terms of patient-robot interaction
A ternary bifurcation diagram for a closed unstirred cerium catalyzed Belousov-Zhabotinsky System in function of the percent in volume of the major components of the system
No full textInterplay between the Belousov-Zhabotinsky reaction-diffusion system and biomimetic matrices
No full textInteractions between reaction–diffusion systems and restricted host environments are a subject of widespread interest. In this work the
behaviour of the Belousov–Zhabotinsky reaction was investigated in lamellar phases formed by phospholipid bilayers with relevance for
biological systems. The influence of the reactive medium on the structure of the lipid matrix and, in turn, the influence of the matrix on
the dynamical evolution of chemical patterns, were studied by small angle scattering
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