Ladder realizations of multivariable positive real functions

Necessary and sufficient conditions are obtained for the realization of an m-variable positive real function (PRF) as the impedence function of a resistively-terminated ladder network of m lossless two-ports connected in cascade. Each two-port is a single-variable lossless ladder with all of its transmission zeros either at the origin or at finity. Conditions are also obtained when each of the two-ports is a Fujisawa-type lowpass ladder.     

Infant approach behavior as related to attachment.

The chief purpose of this study was to identify characteristics that distinguish approach as an attachment behavior from approach serving other behavioral systems. Locomotor approaches of 16 male and 10 female white middle-class infants to an attachment figure (the mother) and to a nonattachment figure (the visitor-observer) were examined under naturalistic conditions at home. Observations were made during 4-hour home visits at 3-week intervals; those from 26 to 54 weeks were used. When approach was examined in a free-choice situation and without regard to behavioral context, infants approached the mother proportionally (though slightly) more often than the visitor (p less than .05). In 2 behavioral contexts, however, spontaneous infant approaches were sharply differential to the mother; approaches accompanied by crying and approaches terminating in a pickup appeal were directed almost exclusively to the mother (p less than .0001 for both). Touching upon completion of the approach was not differential, except in the context of a pickup appeal. Object-oriented approaches were more often directed to the visitor than to the mother (p less than .002) and may be either exploratory or affiliative. It is suggested that neither approach nor touching can be assumed to serve the attachment system without consideration of context- both environmental and behavioral.     

The relative efficacy of vestibular-proprioceptive stimulation and the upright position in enhancing visual pursuit in neonates.

48 healthy neonates born to multiparae were randomly assigned to view a moving stimulus either in the horizontal or the upright position, with or without added vestibular stimulation and with or without pacifier sucking. The infant was shown a moving black line inside a strictly controlled visual environment provided by an apparatus which permitted horizontal and upright positioning and displacement of the infant. Visual tracking was recorded by a concealed TV camera positioned at a constant distance and angle from the infants' eyes in both positions. Quality of tracking during each of 4 trials was scored on a 7-point scale. Results indicate that vestibularproprioceptive stimulation provided to the infant either horizontally or semivertically significantly enhanced his visual tracking, whereas the upright position did not. Pacifier sucking also improved his performace.     

Self-evaluation, social reinforcement, and academic achievement of black and white schoolchildren.

Black and white male schoolchildren covertly evaluated their own performance at a verbal task administered by black and white male experimenters. It was hypothesized that academically successful children would be predisposed to appraise themselves favorably, whereas relatively unsuccessful pupils would be biased toward self-criticism. The covert self-evaluations were assumed to represent at internalization of early experiences of predominantly positive or negative social reinforcement from adult socializing agents. The predicition for self-criticism was upheld in the white experimenter condition but not in the black experimenter condition. Relationships consistent with the theory were found between subjects' self-appraisals and their retrospective reports of positive and negative reinforcements received from parents and teachers in various typical situations. These relationships were more evident for black subjects than for white subjects. The extent to which children's self-praise and self-criticism mediated affect was assessed by means of a color conditioning technique. Contrary to predicition, possibly due to the easy nature of the experimental task.     

A new active R bandpass filter

A new active R filter which realizes a second order bandpass transfer function is given. The network employs only resistors and two operational amplifiers. Sensitivities to all passive and active circuit components are very low. Design equations are given and experimental results are also included.