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Background: Evidence suggests that, as a group, patients with schizophrenia have intellectual deficits that may precede the manifestation of psychotic symptoms; however, how successfully intelligence tests are able to discriminate schizophrenia from other psychotic disorders has yet to be investigated in detail. Methods: Using Wechsler Adult Intelligence Scale-Revised (WAIS-R) data for 55 inpatients with schizophrenia and 28 inpatients with non-schizophrenic psychotic disorders (NSPD) (schizophreniform disorder, brief psychotic disorder, delusional disorder, psychotic disorder due to a general medical condition, and psychotic disorders not otherwise specified), intelligence performance was compared between schizophrenia and NSPD and among different subtypes of schizophrenia. Results: There were no significant differences in intelligence quotient (IQ), verbal IQ (VIQ) and performance IQ (PIQ) discrepancy, and subtest scores of WAIS-R between the patients with schizophrenia and those with NSPD. These diagnostic groups were not discriminated well by any WAIS-R variables. Schizophrenia patients with prominent negative symptoms, on the other hand, had a significantly larger IQ discrepancy (VIQ greater than PIQ) than those without prominent negative symptoms and NSPD patients. Intelligence performance in schizophrenia did not differ with respect to diagnostic subtypes and longitudinal courses. Conclusions: The current study failed to show diagnostic usefulness of WAIS-R in discriminating schizophrenia and other psychoses. A diagnosis of schizophrenia does not significantly impact intellectual deficits in psychotic disorders.

Experiments were carried out to study the effects of surface polishing and annealing of ceramic specimens on the dielectric breakdown characteristics of their surfaces. It was found that when the samples were annealed at 1000[degrees]C, allowing the residual stresses in their surfaces to decrease, the breakdown voltage rose, whereas with the polished samples, reductions of residual stresses resulted in a slight rise of the breakdown voltage. Prior to dielectric breakdown, a surface glow was observed, due to luminescence from electron bombardment and insulator surface defects. The starting voltage of luminescence rose when residual stresses were reduced. It is suggested that the mechanical strain due to surface defects contributes to dielectric breakdowns on ceramic surfaces.

Using a scanning electron microscope (SEM) and a laser microscope, we observed micro-flakes and particles on machined Cu-Cr contacts which were considered to be built-up edges due to machining. A large number of microparticles of 5.7 - 8.7 X [10.sup.3] from contact surface of 1 [cm.sup.2], were generated from the machined Cu-Cr contacts during opening and closing operations of normal current. The size of typical microparticles was some tens [[micro]meters] and those larger than 100 [[micro]meters] were occasionally observed. This implies that the surface of machined Cu-Cr contacts must be treated by any means when they are used for vacuum interrupters. Current conditioning is one of the effective surface treatment. Although the surface roughness of the contacts increases through the current conditioning, the improvement of insulating ability is brought by the elimination of micro-flakes and particles and by the formation of fine structure layer preventing partial detachment of the contact material.

The performance of vacuum circuit breakers in switching shunt capacitors depends much more on in-rush current than on interrupting current. This is because when contacts that were fused together by pre-arcs during contact closing are forcibly separated, large protrusions are formed on the contact surface, making it easier for microparticles to be detached from the protrusions. Microparticles are also produced on the entire surface of contacts by mechanical impact or cold weld. Current interruption of a certain magnitude, however, has a conditioning effect because moderate arcs can eliminate such microparticles and lower the protrusions. To clarify the relationship between the behavior of microparticles and the dielectric breakdown, a laser scattering technique was employed. We found a microparticle-induced breakdown phenomena that could explain the mechanism of long delayed restrikes that is occasionally observed in vacuum circuit breakers.

This paper describes the temporal characteristics of surface charging on a cylindrical insulator made of polymethylmethacrylate (PMMA) resin or alumina ceramic. The insulator is subjected to a dc voltage step or to a trapezoidal voltage in vacuum. The charging is observed by using an electrostatic probe located at the surface of the cathode close to the triple junction where the insulator, cathode and vacuum meet. The probe signal shows a step increase associated with the charging. The interval between the voltage rise and the charging, which is defined as the delay time of charging in this paper, ranges from [10.sup.-5] s to 10 s depending on the material and the applied voltage. It also depends on the condition of the insulator-cathode interface, the electrical prestress and the surface roughness of the insulator. Among these factors, the surface roughness has the largest effect on the delay time. Two-dimensional Monte Carlo simulation based on the secondary emission electron avalanche model has been performed to analyze the charging progress. During the delay period, positive charge accumulates on the surface of the insulator near the cathode, which further accelerates the charging.