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991.
A questionnaire survey of career choices was carried out among 112 medical graduates, after one year's internship (group I), during their National Youth Corps programme in Kaduna, Lagos, Cross River and Oyo states of Nigeria, and 365 final-year medical undergraduates (group 2) in the colleges of medicine in the corresponding states. A total of 13% in group I and 40% in group 2 were undecided as regards their first choice. Obstetrics and gynaecology was the most popular first choice in both groups. General practice ranked fifth among group I, but displaced surgery to rank second among group 2. The differences were statistically significant. A total of 41% of group I and 46% of group 2 preferred to work in a teaching hospital, reflecting the high preference for surgical specialties. Twenty-six per cent and 33.7% of respondents in groups 1 and 2 respectively wished to own their own practice or work in the private sector. General practice is a new specialty and its growth is supported by a national postgraduate training programme. A shift towards general practice is seen compared with previous studies of career preference among Nigerian medical graduates and students. This may be due to a changing balance of supply and demand in the medical work-force, or a better assessment of the nation's health problems and manpower needs.  相似文献   
992.
Structure of receptive fields of visually sensitive neurons in areas CA1 and CA3 of the dorsal hippocampus was investigated in alert cats with the brain-stem pretrigeminal section. The receptive field (RF) structure of 76 hippocampal neurons was analyzed by methods of scanning the RF by moving stimuli and mapping all their surface by a stationary flashing spot. According to presented data the neurons were classified into three groups: neurons with homogeneous structure of the RF (54%), with nonhomogeneous (28%) and neurons more sensitive to stimulus motion (18%) than to a stationary flashing light. Experiments have shown that responses of hippocampal neurons are highly specific ones. Thus, 9% of neurons with the nonhomogeneous RF structure have shown specific responses to variation of the contrast and contours of moving stimuli. The presented results show that hippocampal visually driven neurons have well developed mechanism for processing visual sensory information and apparently this quality ensures participation of the limbic system in visually controlled behavior of the animal.  相似文献   
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994.
Medical experts have disputed whether childhood cyclic vomiting is a manifestation of epilepsy or a migraine equivalent. Quantitative EEG provides an objective measure of changes in brain activity during and between episodes. This paper reports reversible changes involving two episodes in a patient whose history included cyclic vomiting and emotional/behavioural problems. Abnormal delta activity seen during both episodes resolved at follow-up, when the patient asymptomatic. The brain wave changes counter the hypothesis that vomiting in these patients is psychosomatic, and support the interpretation of cyclic vomiting as a migraine equivalent.  相似文献   
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A model of sleep phasic events such as vertex waves, K complexes, delta waves and sleep spindles is proposed. It consists of feedback loops that are driven by white noise (simulating tonic delta and sigma activity) and by isolated random impulses, simulating vertex waves or K complexes, depending on the background tonic activity. A model-based method for the detection of sleep phasic events was implemented in a personal computer. Its performance was investigated using simulated and real whole-night EEG signals. The method was able to detect K complexes and vertex waves in a reliable way in spite of their variable shapes and in the presence of a variety of background activities. The detector appears to have superior performance to those so far reported in the literature. The performance of the detector was also compared to that of an electroencephalographer using normal sleep EEG records of 8 h duration from 6 subjects. The performance was satisfactory both in terms of accuracy and reliability. The problem of detecting K complexes in stages 3 and 4 of sleep is discussed.  相似文献   
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Sodium nucleinate, an officinal preparation (Na PHK), added to the growth medium in concentrations of 10 to 50 micrograms/ml enhanced the growth of hybridoma cells in vitro. Na PHK presence in the cultivation medium in the above concentrations enhanced the specific antibody-producing activity of hybridomas.  相似文献   
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