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181.
T. A. Taran 《Automation and Remote Control》2001,62(10):1632-1644
The design of reflexive behavior models for situation specific choice is investigated under the assumption that the model is based on multi-valued Boolean scales. Conditions for a realistic choice under which an agent can realize his desires are formulated. Reflexive control and programming in which choice is subject to outer pressure are studied. 相似文献
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A rational approach to hemodialysis access in the patient with renal failure requires an understanding of many factors. The initial approach to such patients and subsequent decisions have a significant impact on quality of life as well as the morbidity of access choices. Autogenous vascular access remains the gold standard in the care of these patients. Alternatives are less desirable but are necessary in an increasing number of situations. Careful thought before embarking on a procedure will provide better long-term function and preserve the patient's options for the future. 相似文献
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VG Savchenko EN Parovichnikova VG Isaev IA Demidova RG Kuliev EO Gribanova GA Kliasova RA Kucher AN Sokolov KS Momotiuk IuV Ol''shanskaia NG Tiurina LIu Tikhonova GM Galstian VM Budianski? EA Belousov VA Lapin SV Voloshin TS Konstaninova LB Filatov ON Porokhina EA Smirnova 《Canadian Metallurgical Quarterly》1998,70(7):5-11
189.
MV Vasin GA Chernov LV Koroleva TS L''vova MM Abramov VV Antipov NN Suvorov 《Canadian Metallurgical Quarterly》1996,36(1):36-46
Output from the interpositus nucleus can inhibit the inferior olive, probably via the GABA-ergic nucleo-olivary pathway. It has been suggested that the function of this inhibition might be to regulate synaptic plasticity resulting from parallel fibre/climbing fibre interaction in cerebellar Purkinje cells, by providing negative feedback information to the olive. Thus, when a learned response, generated by the interpositus nucleus, reaches a sufficient amplitude, the olive would be inhibited and further learning blocked. This suggestion was tested in a classical conditioning paradigm. Decerebrate ferrets were trained using electrical skin stimulation of the forelimb as the conditioned stimulus (CS) and periorbital stimulation as the unconditioned stimulus (US). Climbing fibre responses evoked in Purkinje cells by the US were recorded as surface field potentials in the part of the c3 zone controlling eyeblink. It was found that the CS did not inhibit the olive at the beginning of training, but when conditioned responses were large, the olive was inhibited by the CS in some animals. After a number of unpaired CS presentations, which caused extinction of the conditioned response, the inhibition disappeared. The size of individual conditioned responses correlated negatively with the size of the climbing fibre responses evoked by the US. Climbing fibre responses evoked by direct stimulation of the olive were also inhibited. It was concluded that cerebellar output during performance of a conditioned response inhibits the inferior olive. The results thus support the hypothesis of a cerebellar locus of conditioning and are consistent with the proposed role of cerebello-olivary inhibition. 相似文献
190.
SP Alsemgeest GA van ''t Klooster AS van Miert CK Hulskamp-Koch E Gruys 《Canadian Metallurgical Quarterly》1996,53(1-2):179-184
OBJECTIVE: To determine placental transfer of ketanserin and to assess the effect of serotonin-2 receptor blockade by ketanserin on serotonin- and phenylephrine-induced vasoconstriction. STUDY DESIGN: Five chronically instrumented pregnant ewes at 120 days gestation were injected with 20 mg ketanserin i.v., and fetal and maternal arterial samples were obtained at predetermined intervals to assess placental transfer. Maternal and fetal responses of blood flows and pressures were determined after injected of serotonin (20 micrograms/kg) or phenylephrine (10 micrograms/kg) before and after ketanserin (0.75 mg/kg). RESULTS: In the ewe, ketanserin is transferred across the placenta and reaches measurable levels in the fetal lamb. Ketanserin blocks the maternal and fetal serotonin-induced rise in arterial pressure, but not the serotonin-induced reduction in uterine blood flow. CONCLUSION: In the pregnant ewe, the serotonin-induced rise in maternal and fetal blood pressure is effectively antagonized by ketanserin, whereas the serotonin-induced reduction in uterine blood flow is not. 相似文献