1,097 research outputs found
Synaptic transmission as a cooperative phenomenon in confined systems
In this review paper, the theory of synaptic transmission (ST) was developed
and discussed. We used the hypothesis of isomorphism between: (a) the
cooperative behavior of mediators --- acetylcholine molecules (ACh) and
cholinoreceptors in a synaptic cleft with binding into mediator-receptor (AChR)
complexes, (b) the critical phenomena in confined binary liquid mixtures. The
systems of two (or three) nonlinear differential equations were proposed to
find the change of concentrations of ACh, AChR complexes, and ferment
acetylcholinesterase. The main findings of our study: the linear size of the
activation zone was evaluated; the process of postsynaptic membrane activation
was described as a cooperative process; different approximations of ACh
synchronous release were examined; stationary states and types of singular
points were studied for the proposed models of ST; the nonlinear kinetic model
with three order parameters demonstrated a strange-attractor behavior.Comment: 12 pages, 1 figur
Optimum pulse shapes for stimulated Raman adiabatic passage
Stimulated Raman adiabatic passage (STIRAP), driven with pulses of optimum
shape and delay has the potential of reaching fidelities high enough to make it
suitable for fault-tolerant quantum information processing. The optimum pulse
shapes are obtained upon reduction of STIRAP to effective two-state systems. We
use the Dykhne-Davis-Pechukas (DDP) method to minimize nonadiabatic transitions
and to maximize the fidelity of STIRAP. This results in a particular relation
between the pulse shapes of the two fields driving the Raman process. The
DDP-optimized version of STIRAP maintains its robustness against variations in
the pulse intensities and durations, the single-photon detuning and possible
losses from the intermediate state.Comment: 8 pages, 6 figures. submitted to Phys. Rev.
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