Related Experiment Video
Updated: Jun 3, 2026
08:32
External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures
Published on: May 7, 2017
Gradient induced spiral drift in heterogeneous excitable media.
Parisa Sadeghi1, Harm H Rotermund
1Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada.
Chaos (Woodbury, N.Y.)
|April 5, 2011
Summary
A thermal gradient drives spiral pattern drift in catalytic CO oxidation on platinum. This study reveals new insights into pattern dynamics in nonlinear excitable systems.
Area of Science:
- Chemical Kinetics
- Surface Science
- Nonlinear Dynamics
Background:
- Nonlinear excitable systems exhibit pattern formation like spirals.
- Resonant forcing can induce spiral drift in these systems.
- CO oxidation on platinum is a model heterogeneous catalytic reaction.
Purpose of the Study:
- Investigate the effect of a linear thermal gradient on spiral dynamics in CO oxidation on platinum (110).
- Determine if a thermal gradient can act as an internal forcing mechanism for spiral drift.
Main Methods:
- Utilized both computational simulations and experimental approaches.
- Studied the CO oxidation reaction on a platinum (110) single crystal surface.
Main Results:
- A spatial thermal gradient was shown to induce spiral pattern drift.
- The observed drift exhibited components both parallel and perpendicular to the applied gradient.
Conclusions:
- Spatial thermal gradients can serve as an internal forcing drive for spiral dynamics.
- This finding advances the understanding of pattern formation and control in heterogeneous catalysis.
Related Concept Videos
01:19Drift Velocity
The high speed of electrical signals results from the fact that the force between charges acts rapidly at a distance. Thus, when a free charge is forced into a wire, the incoming charge pushes other charges ahead due to the repulsive force between like charges. These moving charges move the charges farther down the line. The density of charge in a system cannot easily be increased, so the signal is passed on rapidly. The resulting electrical shock wave moves through the system at nearly the...
01:30The Hall Effect
Edwin H. Hall, in the year 1879, devised an experiment that could be used to identify the polarity of the predominant charge carriers in a conducting material. From a historical perspective, this experiment was the first to demonstrate that the charge carriers in most metals are negative.
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
01:21Carrier Transport
The generation of electrical current in semiconductors is fundamentally driven by two mechanisms: drift and diffusion. These processes are essential for the functionality and performance of semiconductor-based devices.
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
01:17Theory of Metallic Conduction
The conduction of free electrons inside a conductor is best described by quantum mechanics. However, a classical model makes predictions close to the results of quantum mechanics. It is called the theory of metallic conduction.
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
01:23Induced Electric Fields
The fact that emfs are induced in circuits implies that work is being done on the conduction electrons in the wires. What can possibly be the source of this work? We know that it’s neither a battery nor a magnetic field, as a battery does not have to be present in a circuit where current is induced, and magnetic fields never do any work on moving charges. The source of the work is in fact an electric field that is induced in the wires. For example, if a stationary conductor is placed in a...