Model analysis for a current-step-like structure in a high Tc Josephson device coupled to a microwave signal

2005 ◽  
Vol 97 (6) ◽  
pp. 063906 ◽  
Author(s):  
Yoshinao Mizugaki ◽  
Jian Chen
Keyword(s):  
Model Analysis ◽  
Microwave Signal ◽  
High Tc ◽  
Current Step ◽  
Josephson Device ◽  
A Current

scholarly journals Interpretation of the Repetitive Firing of Nerve Cells

1962 ◽  
Vol 45 (6) ◽  
pp. 1163-1179 ◽  
Author(s):  
M. G. F. Fuortes ◽  
Francoise Mantegazzini
Keyword(s):  
Nerve Cells ◽  
Principal Factor ◽  
Current Intensity ◽  
Moderate Intensity ◽  
Repetitive Firing ◽  
Important Process ◽  
Current Step ◽  
After Effects ◽  
Graded Activity ◽  
A Current

Eccentric cells of Limulus respond with repetitive firing to sustained depolarizing currents. Following stimulation with a step of current, latency is shorter than first interval and later intervals increase progressively. A shock of intensity twice threshold can evoke firing 25 msec. after an impulse. But in the same cell, a current step twice rheobase evokes a second impulse more than 50 msec. after the first, and current intensity must be raised to over five times rheobase to obtain a first interval of about 25 msec. Repetitive firing was evoked by means of trains of shocks. With stimuli of moderate intensity, firing was evoked by only some of the shocks and intervals between successive impulses increased with time. This is ascribed to accumulation of refractoriness with successive impulses. Higher frequencies of firing are obtained with shocks of intensity n x threshold than with constant currents of intensity n x rheobase. It is concluded that prolonged currents depress the processes leading to excitation and that (in the cells studied) repetitive firing is controlled both by the after-effects of firing (refractoriness) and by the depressant effects of sustained stimuli (accommodation). Development of subthreshold "graded activity" is an important process leading to excitation of eccentric cells, but is not the principal factor determining frequency of firing in response to constant currents.

A model for rebound bursting in mammalian neurons

1994 ◽  
Vol 346 (1316) ◽  
pp. 129-150 ◽  
Keyword(s):  
Bifurcation Diagram ◽  
Dynamic Properties ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Simplified Model ◽  
Thalamic Neuron ◽  
Subthreshold Region ◽  
Current Step ◽  
A Current ◽  
Three Dimensional Space

In this paper we begin by simplifying our previous model of a thalamic neuron (Rose & Hindmarsh Proc. R. Soc. Lond . B 237, 289-312 (1989 b )) by removal of the A current. A Ca 2+ -activated K + current, with Ca 2+ entering through T channels, is then added to give a model for a class of mammalian neurons in which the membrane potential oscillates in the subthreshold region following a hyperpolarizing current step. The properties of the model are represented using an experimentally observable bifurcation diagram. In the subthreshold region only three variables are required to explain the essential dynamic properties of the cell. In this three-dimensional space the solutions tend to lie on a surface which resembles a paraboloid. We use a simplified model of this model to explain both the dynamics of the solutions on this surface and the form of the bifurcation diagram.

MAGNETIC FIELD CONTROLLED SUPERCONDUCTING - RESISTIVE AND RESISTIVE - SUPERCONDUCTING TRANSITIONS IN HIGHLY HYSTERETIC JOSEPHSON JUNCTIONS

2003 ◽  
Vol 17 (04n06) ◽  
pp. 757-761
Author(s):  
R. LATEMPA ◽  
G. CARAPELLA ◽  
G. COSTABILE ◽  
G. P. PEPE ◽  
L. PARLATO ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Josephson Junction ◽  
Pulse Shape ◽  
Suitable Choice ◽  
Control Line ◽  
Magnetic Pulse ◽  
Flip Flop ◽  
Current Step ◽  
The Magnetic Field ◽  
A Current

We report measurements of the switching induced by a rapidly varying magnetic field in a single, small, fully hysteretic Josephson junction. We demonstrate that the variation of the magnetic field, generated by a current step in a control line deposited on the top of the junction, can control the transitions from Josephson branch to the resistive branch and vice versa. The transition from resistive branch to Josephson branch is not trivial for an hysteretic junction. With a suitable choice of the magnetic pulse shape, a "deterministic flip-flop regime" can be achieved in this system.

Basic characteristics of high-Tc superconductor as a current-limiting element

1992 ◽  
Vol 112 (5) ◽  
pp. 66-77
Author(s):  
Koichi Nakamura ◽  
Yasukazu Ito ◽  
Takao Kawashima
Keyword(s):  
High Tc ◽  
High Tc Superconductor ◽  
Current Limiting ◽  
Basic Characteristics ◽  
A Current

Improved CO Tolerance With PtRu Anode Catalysts in ABPBI Based High Temperature Proton Exchange Membrane Fuel Cells

2012 ◽  
Vol 9 (3) ◽  
Author(s):  
Christian Oettel ◽  
Liisa Rihko-Struckmann ◽  
Kai Sundmacher
Keyword(s):  
High Temperature ◽  
Proton Exchange Membrane ◽  
Negative Influence ◽  
Proton Exchange ◽  
Voltage Response ◽  
Anode Catalyst ◽  
Current Step ◽  
Co Tolerance ◽  
Exchange Membrane ◽  
A Current

The potential to improve the CO tolerance of a high temperature proton exchange membrane fuel cell (HT-PEMFC) was investigated by introducing a platinum-ruthenium alloy as anode catalyst. The electrolyte was a H3PO4 doped poly-2,5-benzimidazole polymer (ABPBI). The experiments were carried out at the temperatures between 403 and 443 K with a CO concentration in the H2 feed gas between 0 and 6.5 vol%. The alloy anode catalyst lowers significantly the negative influence of CO in the feed, exceeding the known temperature dependent CO poisoning mitigation in HT-PEMFCs. It was found that the voltage loss of a HT-PEMFC with PtRu anode catalyst was lower than that of a similar cell equipped with Pt anode. The dynamic cell voltage response to a current step was analyzed under CO influence, as well. The PtRu bimetallic anode electrode was found to lower the observed voltage overshoot behavior after a current step, if compared to conventional Pt anode.

All Refractory, High Tc Josephson Device Technology

1984 ◽  
pp. 547-558 ◽  
Author(s):  
E. J. Cukauskas ◽  
M. Nisenhoff ◽  
H. Kroger ◽  
D. W. Jillie ◽  
L. R. Smith
Keyword(s):  
High Tc ◽  
Josephson Device ◽  
Device Technology

AC susceptibility with superimposed DC magnetic field in a current biased granular high Tc superconductor

1994 ◽  
Vol 235-240 ◽  
pp. 3227-3228
Author(s):  
G. Codner ◽  
H. Ferrari ◽  
C. Acha ◽  
V. Bekeris ◽  
P. Levy
Keyword(s):  
Magnetic Field ◽  
Ac Susceptibility ◽  
High Tc ◽  
Dc Magnetic Field ◽  
High Tc Superconductor ◽  
A Current
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