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71.
Bursts of beta-frequency (15-35 Hz) electroencephalogram activity occur in the olfactory system during odour sampling, but their mode of propagation within the olfactory system and potential contribution to the mechanisms of learning and memory are unclear. We have elicited large-amplitude beta activity in the rat olfactory system by applying noxious olfactory stimuli (toluene), and have monitored the bursts via chronically-implanted electrodes. Following exposure to toluene, coherent bursts with a peak frequency of 19.8 +/- 0.9 Hz were observed in the olfactory bulb, piriform cortex, entorhinal cortex and dentate gyrus. The timing of the bursts and the phases of electroencephalogram cross-spectra indicate that beta bursts propagate in a caudal direction from the olfactory bulb to the entorhinal cortex. The time delays between peaks of bursts in these structures were similar to latency differences for field potentials evoked by olfactory bulb or piriform cortex test-pulses. Peaks of burst cycles in the dentate region, however, were observed just prior to those in the entorhinal cortex. Surprisingly, power in toluene-induced beta-frequency oscillations was not increased following long-term potentiation induced by tetanic stimulation of the olfactory bulb, piriform cortex and entorhinal cortex. The activity of local inhibitory mechanisms may therefore counteract the effects of synaptic enhancements in afferent pathways during beta bursts. Low-frequency electrical stimulation of the piriform cortex was most effective in inducing coherent oscillatory responses in the entorhinal cortex and dentate gyrus at stimulation frequencies between 12 and 16 Hz. The results show that repetitive polysynaptic volleys at frequencies in the beta band induced by either toluene or electrical stimulation are transmitted readily within the olfactory system. The propagation of neural activity within this frequency range may therefore contribute to the transmission of olfactory signals to the hippocampal formation, particularly for those odours which induce high-amplitude bursts of beta activity.  相似文献   
72.
TINA, the Telecommunications Information Networking Architecture, is a software architecture for services provided on public and private networks. TINA NRIM adds on the existing concepts and supports a host of new multimedia services that can not be supported by the existing information models. It is expected that network information models will be aligned with those defined by ATM Forum and ITU-T SG15. The authors show a generic information model of network resources, which can be applied to different network technologies. The model contains a number of abstraction levels of network resources. The highest level of abstraction, which is offered at the interface between the network resources and services levels, is defined in terms of a connection graph. The connection graph is an abstract representation of resources describing the connectivity between stream interfaces (media flows). This graph can be used to specify end-to-end connectivity that spans through several layer networks. Thus, a line in the connection graph can be supported by a sequence of trails. The trail, in its turn, consists of subnetwork connections and/or tandem connections. The generic information model with appertained abstraction levels is very well suited to the TINA connection management architecture  相似文献   
73.
Design issues for monolithic DC-DC converters   总被引:3,自引:0,他引:3  
This paper presents various ideas for integrating different components of dc-dc converter on to a silicon chip. These converters are intended to process power levels up to 0.5W. Techniques for integrating capacitors and design issues for MOS transistors are discussed. The most complicated design issue involves inductors. Expressions for trace resistance and inductance estimation of on-chip planar spiral inductor on top metal layer of CMOS process are compared. These inductors have high series resistance due to low metal trace thickness, capacitive coupling with substrate and other metal traces, and eddy current loss. As an alternative, a CMOS compatible three-dimensional (3-D) surface micromachining technology known as plastic deformation magnetic assembly (PDMA) is used to fabricate high quality inductors with small footprints. Experimental results from a monolithic buck converter using this PDMA inductor are presented. A major conclusion of this work is that the 3-D "post-process" technology is more viable than traditional integrated circuit assembly methods for realizing of micro-power converters.  相似文献   
74.
In this paper a two-dimensional (2-D) dynamic model, based on a tensor formulation and solved numerically by combining finite elements and finite differences, is proposed and used for analyzing nematic liquid crystal (LC) test cells with interdigital electrodes. We compare theoretical and experimental results concerning the switching behavior, response mechanism, and viewing angle characteristics of nematic LC pixel structures which use the in-plane-switching (IPS) mode. The good agreement observed between theory and experiment in terms of electro-optical properties validates our modeling and demonstrates its potential for design optimization. We show that the proposed LC test cells, using the in-plane-switching mode, ensure switching-ON and -OFF response times of 22 and 28 ms, respectively, and excellent viewing angle characteristics  相似文献   
75.
2 Es with markedly different personality characteristics and styles of interacting with Ss tested male undergraduates (Ns = 22 and 25) for pupillary dilation to pictures of nude and partially clothed women, as well as to pictures of men, and to control pictures. The Ss of E1, an aloof and businesslike graduate student, dilated equally to male and female pictures. The Ss of E2, a casual outgoing undergraduate, dilated more to pictures of women than to those of men. These results indicate that pupillary dilation to sexually provocative stimuli reflect S's relationship to the E and his view concerning permissible emotional responses to the stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
76.
Cutting the suspensory ligament reduced the ovarian content of norepinephrine (NE) to less than half that of controls and only a few blood vessels had perivascular fibers and an occasional nerve remained in the interstitial gland. Cutting the ovarian plexus had a less drastic, but similar effect on the ovarian content of NE and on the pattern of ovarian adrenergic nerves. Cutting both the suspensory ligament and ovarian plexus eliminated visualization of ovarian adrenergic nerves, but some ovarian NE was still measurable. Fluorescence and electron microscopic studies of the suspensory ligament revealed a large adrenergic nerve embedded in smooth muscle of the ligament. The nerve was also acetylcholinesterase-positive. Cutting the celiac plexus or incising a small nerve lateral to the plexus and medial to the origin of the suspensory ligament, had the same effect on the ovarian adrenergic nerves as cutting the suspensory ligament. It is concluded that the extrinsic adrenergic nerves to the rat ovary reach the organ by two routes: one via the nerve in the suspensory ligament (superior ovarian nerve), and one via the traditionally described ovarian plexus along the ovarian artery.  相似文献   
77.
Tested R. L. Cromwell and P. R. Dokecki's (1968) theory that excessive response by schizophrenics to strong aspects of meaning of words and deficient response to weak aspects of meaning reflect an inability to disattend from strong aspects of meaning. 79 schizophrenics (40 off and 39 on drugs) were given 2 multiple-choice subtests asking for identification of aspects of meaning of words. Items of one subtest contained both a strong and a weak aspect of meaning and items of the other contained 2 weak aspects of meaning. The subtests had been matched on difficulty and reliability for 166 normal Ss. The schizophrenics identified weak aspects of meaning no worse when strong aspects of meaning were present than when they were absent. Findings argue against Cromwell and Dokecki's theory. Schizophrenics' excessive response to strong aspects of meaning on other tasks probably reflects a defect in screening and a resultant heightened expression of a normal bias. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
78.
A 28-item true–false scale was constructed to measure schizophrenic body-image aberration. The scale was standardized on both 631 male and 718 female college students and 100 male noncollege normal controls (mean age 31.7 yrs). The 74 male schizophrenic Ss reported more body-image aberration than normal nonstudent Ss, but only a portion of the schizophrenics were deviant. 20 male nonpsychotic clinic clients did not have heightened scores. Correlational findings indicate that schizophrenic body-image aberration is an aspect of a broader perceptual aberration. Scores on body-image aberration were negatively correlated with time since first hospitalization. The Body-Image Aberration Scale had essentially no correlation with the Physical Anhedonia Scale (L. J. Chapman, J. P. Chapman, and M. L. Raulin) for schizophrenics. For nonschizophrenics, however, high scores on the 2 scales accompanied one another significantly less often than expected by chance. It is suggested that the 2 scales may identify alternative manifestations of proneness toward the same schizophrenia. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
79.
A poor response to L-DOPA in addition to parkinsonian, cerebellar, and autonomic signs is commonly regarded as indicative of clinical multiple system atrophy (MSA). We compared the motor response to a single oral administration of 250 mg L-DOPA/25 mg carbidopa in eight MSA patients and eight Parkinson's disease (PD) patients with the "on-off" phenomenon, evaluating L-DOPA peripheral pharmacokinetics. Motor response was consistently good in all PD patients, but only four MSA patients had a (moderate) response. Pharmacokinetic parameters did not differ between the groups. The varying extent of putaminal damage could be responsible for the differing motor response to L-DOPA in MSA patients.  相似文献   
80.
Correlates of psychotic and psychoticlike symptoms were examined in 60 college students who scored deviantly high on the Perceptual Aberration Scale. High scorers on this scale who also scored high on both the Impulsive Nonconformity Scale and the Depression subscale of the General Behavior Inventory (GBI) showed the most deviant psychotic and psychoticlike symptoms. Moreover, performance on a task of referential communication, the Password Task, was significantly related to such symptoms. The Perceptual Aberration Scale, the Impulsive Nonconformity Scale, and the GBI Depression subscale are recommended for concurrent use in mass screening to select individuals likely to exhibit psychotic or psychoticlike symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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