On the Determination of Minimal Facets and Edges of a Polyhedral Set

In this paper we investigate the image of a polyhedral set under a linear map. Moreover, we present an algorithm for the determination of so-called minimal facets and certain minimal irredundant proper edges of a convex polyhedral set in ℝ³. © 1997 John Wiley & Sons, Ltd.     

Is there an optimal factor structure of the Positive and Negative Syndrome Scale in patients with first‐episode psychosis?

The Positive and Negative Syndrome Scale (PANSS) is the most widely used scale to assess a variety of symptoms in patients with schizophrenia and other psychoses. The factor structure of the PANSS has been examined with confirmatory factor analyses in several studies, but not in a well‐defined first‐episode psychosis sample. The aim of this paper is to examine the statistical fit of five different PANSS models in a first‐episode, non‐affective psychosis sample. Confirmatory factor analyses were performed on PANSS data (n = 588). A main criterion for best fit was defined as the Expected Cross Validation Index (ECVI). No tested model revealed an optimally satisfactory model fit index. The Wallwork/Fortgang five‐factor model demonstrated the most optimal psychometric properties. The corresponding subscales of all evaluated five‐factor models were strongly intercorrelated. The Wallwork/Fortgang five‐factor model was found to be statistically and clinically ideal among patients with first‐episode psychosis. Therefore, we recommend this model in forthcoming studies among patients with first‐episode psychosis. However, to prevent the loss of clinically valuable information on an item level, we do not recommend removing any items from the original form. Our study also implies that the specific choice of model will not have a substantial effect on outcome results in studies on the course and outcome in first‐episode psychosis.     

Nascent body ego: Metapsychological and neurophysiological aspects

For Freud, body ego was the organizing basis of the structural theory. He defi ned it as a psychic projection of the body surface. Isakower's and Lewin's classical fi ndings suggest that the body surface experiences of nursing provide the infant with sensory-affective stimulation that initiates a projection of sensory processes towards the psychic realm. During nursing, somato-sensory, gustatory and olfactory modalities merge with a primitive somatic affect of satiation, whereas auditory modality is involved more indirectly and visual contact more gradually. Repeated regularly, such nascent experiences are likely to play a part in the organization of the primitive protosymbolic mental experience. In support of this hypothesis, the authors review fi ndings from a neurophysiological study of infants before, during and after nursing. Nursing is associated with a signifi cant amplitude change in the newborn electroencephalogram (EEG), which wanes before the age of 3 months, and is transformed at the age of 6 months into rhythmic 3-5 Hz hedonic θ-activity. Sucking requires active physiological work, which is shown in a regular rise in heart rate. The hypothesis of a sensory-affective organization of the nascent body ego, enhanced by nursing and active sucking, seems concordant with neurophysiological phenomena related to nursing.