Observing response acquisition: Preference for unpredictable appetitive rewards obtained under conditions predicted by DMOD.

To investigate the preference for unpredictable rewards predicted by the present author and J. T. Daly's (see record 1983-20275-001) modification, known as the DMOD model, of R. A. Rescorla and A. R. Wagner's (1972) previous model of reinforcement, the present author conducted 5 E-maze experiments with 144 male Holtzman rats. In Exps I–V, Ss were given a choice between receiving reward and nonreward in a situation in which stimuli were correlated with reward outcome (predictable situation) vs a situation in which the stimuli were uncorrelated with reward outcome (unpredictable situation). Preference for the unpredictable situation occurred under the following conditions: small (1 37-mg pellet) immediate rewards, small delayed (15-sec) rewards when the cues correlated with reward outcome were absent during the delay interval, large (15 pellets) immediate rewards when a difficult discrimination was required, and when the stimulus predicting nonreward was present at the choice point. Preference for the predictable situation was strongest if reinforcement was delayed and large or if the stimulus predicting reward was present at the choice point. A weaker preference for the predictable situation occurred if reinforcement was immediate, large, and required a simple discrimination or if reinforcement was large and delayed and the cues that correlated with reward outcome were absent during the delay interval. Findings support the predictions of the DMOD model of appetitive learning. (33 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The Instructional Hierarchy: A conceptual model for understanding the effective components of reading interventions.

Examines the Instructional Hierarchy, a conceptual framework for refining the notion of academic responding according to a learning hierarchy and describing treatment components (e.g., modeling, drill, reinforcement, etc.) that correspond to different stages of the learning hierarchy. Academic responding occurs within the context of classroom curricular activities. Teachers allocate time to instruction; students are either academically engaged or not engaged during that time. The research on the relationship between different treatment components and student responding is reviewed and recommendations for the practice of academic intervention in reading and for future research in this area are made. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychophysiological treatment of migraine and tension headaches: A 12-month follow-up.

Conducted a 12-mo follow-up of the present authors' (1983) study population of chronic headache sufferers by telephone interviewing 31 chronic migraine and 25 chronic tension headache patients (aged 18–61 yrs) who had been treated with EMG, muscle relaxation, and fingertip temperature training to test a hypothesis of biofeedback placebo effects. A previous 3-mo follow-up had revealed that all treatments had produced significant improvement, and relaxation was not as good as the biofeedback devices for obtaining a reduction in monthly headache hours. At 12-mo follow-up, the 3-mo improvement was sustained overall, but migraineurs as a group appeared to regress slightly, while tension patients improved significantly in the interim. On the basis of a 50% reduction in symptomatology, biofeedback treatment was significantly superior to relaxation for tension headaches, although this had not been true at the 3-mo assessment. Temperature training was at least as effective as EMG for both headache groups. In view of these results, biofeedback treatment is viewed less as placebo administration and more as a secondary reinforcer of a specific but unknown physiological response. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetry in bicycle ergometer pedalling

The effects of changes in speed and resistance setting on the bilateral symmetry of work output on the bicycle ergometer were studied. The cranks of a Monarch bicycle ergometer were instrumented with foil strain gauges and the bridge outputs were integrated on-line and analyzed by a program running in a Hewlett Packard 2115A computer. Twenty male subjects performed three thirty-second trials at each of nine speed and resistance combinations. Indices of asymmetry from 66-178 were found using kicking dominance (n = 20) and 56-135 using a strength dominance classification (n = 13). Day to day reliability of the index of asymmetry was found to be only 0.47; within day reliability was 0.87 for day one and 0.79 for day two. No significant effects for speed or resistance changes were shown on either day for the strength dominant subjects. When kicking dominance was considered main effects were encountered on both days for speed although there was no clear directional trend. The findings of these experiments have important implications for studies where measurements are made on the lower extremity during cycle ergometer exercise, and for competitive cyclists engaged in endurance competition.     

Finite elements for field problems in cylindrical co-ordinates

This paper deals with the extension of the finite element method as applied to the solution of the Laplace or wave equation to cylindrical co-ordinate systems. The base matrices required for solving problems governed by these equations are derived for circular polar, elliptic cylinder and parabolic cylinder co-ordinates. The matrices allow problems whose boundaries are described as co-ordinate surfaces in cylinder co-ordinates to be attacked directly by the finite element method. The subject is discussed from the point of view of one interested in electromagnetic wave propagation in uniform waveguide structures.     

An instrument for mass analysis using a laser

An apparatus has been constructed that will give a complete elemental analysis of a solid sample in the size range 10^–8 to 10^–10 g. The beam from aQ-switched ruby laser is focused on to the sample, and the ions produced are used to give time resolved spectra. Analysis of several types of sample is described, illustrating the capabilities and limitations of the instrument.     

A flat-feed technique for phased arrays

A recently developed phased-array feed configuration offering significant advantages over the conventional space, corporate, and series feed techniques is described. This technique, referred to as the "flat feed," allows power division for monopulse sum and difference pattern illumination functions in a feed depth of less than a half-wavelength with low loss. The technique used to extract energy from the power divider, which consists in part of a radial transmission line, results, in its simplest configuration, in a circular grid of antenna elements. Relations governing the circular grid array geometry design are derived which relate the angular locations of attenuated grating lobes to the spacing between the rings of radiating elements. ExperimentalS-band hardware, built to prove the feed technique, is described. It includes a multimode launcher with measured coupling between circular wavegulde sum (TM_{01}) and difference (TE_{11}) modes of less than -37 dB; a seven-ring 1:195 radial power divider measured across a 10-percent band to have insertion loss of 0.1 dB and rms phase and amplitude deviations of less than3.5degand 0.47 dB; a 144-element array whose measured sum and difference beam radiation patterns are compared with calculated patterns for scan angles out to60degand whose sum port VSWR, measured across a 10-percent band, was under 1.8:1 with the array steered to broadside, and under 1.5:1 for other scan angles out to60deg.     

Fiber Optic Intermodulation Distortion

In analog frequency-division multiplexed fiber optic systems, laser nonlinearities transfer energy between the different carriers, resulting in intermodulation distortion and interference. A third-order polynomial without memory is used to model the nonlinearity. The FM frequency-division multiplexed (FM/FDM) signal consists of a set of FM carriers at frequencies.N_{omega 0}, whereN = L, L + 1, L +2, ... , M. The video distortion introduced by the nonlinearity is determined for various types of second- and third-order intermodulation terms. The intermodulation distortion frequency spectrum is determined for FM signals with assumed Gaussian spectra.