Biomedical subjects

Z Q Bai

Publications and source records attributed to Z Q Bai.

2 recordsLinked to original sources

PubMed1999

Chaotic dynamics in classical s-wave helium.

Classical dynamics of s-wave helium in the case of E<0 is investigated by the geometric method. The ambiguousness of the orbits after two-electron critical collision (TECC) is eliminated by confining the motion to the fundamental domain defined by r1>r2. Scattering orbits are classified into undelayed and delayed (resonant) according to whether they can avoid the recurrence of reaction. A global Smale horseshoe on the surface of section is constructed for the case of Z=2 which implies that the bounded motion is purely chaotic and explains the onset of the chaotic (resonant) scattering when the incident energy is below a threshold. Immediately below the threshold, the probability of resonant scattering increases linearly with the energy difference. Moreover, we found that the permitted code sequences for the scattering orbits at a given incident energy are determined by the principal TECC orbit. Compared with the e-Ze- collinear helium, the s-wave helium is less chaotic and exhibits a more intricate threshold behavior.

Journal Article↗

PubMed1993

[Effect of electrical stimulation of second somatosensory cortex on the response of primary somatosensory cortex to C-fiber inputs].

When the projecting point of saphenous nerve in second somatosensory cortex (S II) of cat was stimulated, the evoked potentials elicited by C-fiber inputs of saphenous nerve recorded in the primary somatosensory cortex (C-CEP) might be either inhibited or facilited according to whether the superficial and/or the deeper layer of the cortex was stimulated. The inhibition was expressed as a decrease of amplitude and prolongation of latency of C-CEP; while the facilitation, as an increase of amplitude and duration of C-CEP. When the superfaicial layer of S II was stimulated by weaker current, both inhibitory and facilitatory effects could be observed, but only inhibitory effect was observed, when the deep layer was stimulated. With the same intensity of stimulation, inhibitory effect was more pronounced when the deep layer rather than the superficial layer was stimulated. It is suggested that S II may play a role in the modulation of C-CEP of S I.

Animals↗