Multiplicative updates for nonnegative quadratic programming

Many problems in neural computation and statistical learning involve optimizations with nonnegativity constraints. In this article, we study convex problems in quadratic programming where the optimization is confined to an axis-aligned region in the nonnegative orthant. For these problems, we derive multiplicative updates that improve the value of the objective function at each iteration and converge monotonically to the global minimum. The updates have a simple closed form and do not involve any heuristics or free parameters that must be tuned to ensure convergence. Despite their simplicity, they differ strikingly in form from other multiplicative updates used in machine learning. We provide complete proofs of convergence for these updates and describe their application to problems in signal processing and pattern recognition.     

Architectural Aesthetics in the Analytic Tradition: A New Curriculum

Architecture programs should include a curriculum on philosophy of architecture in the analytic philosophical tradition. I describe such a curriculum and distinguish it from both the typical architectural theory curriculum and the typical philosophical aesthetics courses. Without such a curriculum, students likely lack exposure to the philosophical approach to aesthetics that is dominant in American universities.     

Nicotine withdrawal in chippers and regular smokers: Subjective and cognitive effects.

From previous studies, chippers (very light, long-time cigarette smokers) seem not to be nicotine dependent, despite decades of smoking. The effect of tobacco deprivation on chippers' withdrawal reactions was examined. Matched groups of 26 chippers and 25 regular smokers were studied while abstaining or smoking for 2-day blocks, with assessments administered 5 times daily by palm-top computers. As hypothesized, chippers showed no changes as a result of nicotine deprivation. In contrast, regular smokers demonstrated distinct changes in craving, mood, arousal, and sleep disturbance. The computers also tested participants' cognitive performance. Unlike chippers, regular smokers' performance on complex tasks was slower under deprivation; the effect could not be explained by changes in motor performance or simple reaction time. Results suggest performance may have been improved by nicotine rather than worsened by withdrawal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Peer-tutoring: Applied behavior analysis working in the classroom.

Schools often use peer-tutoring as a corrective program for students who are experiencing difficulties academically. Given appropriate behavioral structure, peer-tutoring can become a powerful classwide instructional intervention. An historical perspective on the use of students as teachers for their peers is given in this selective literature review. Also, information on the efficacy of considering behavioral function and structure and data addressing ecobehavioral variables to establish a productive learning environment are provided. The authors emphasize infusing peer-tutoring programs with applied behavior analysis techniques to increase the academic success of large numbers of students cost effectively. Peer-tutoring programs are considered to be a way for applied behavior analysts to gain greater access to American school learning environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transfer function analysis of respiratory sinus arrhythmia: a measure of autonomic function in diabetic neuropathy

Standard techniques measuring heart rate (HR) variability do not account for its dependence on the rate and depth of respiration or measure the time relationship between changes in lung volume and HR. We used transfer function analysis to determine the magnitude and time relationship of the HR response to a known change in lung volume in controls and diabetics. This technique demonstrated significant differences between controls and diabetics with varying degrees of autonomic dysfunction. Specifically, reduced supine vagal and increased supine sympathetic HR modulation was found with progression of the autonomic neuropathy. In response to postural change the normal diabetics displayed impaired sympathetic HR modulation. Transfer function analysis yields new insight into the sequence of changes that occur with diabetic autonomic neuropathy and provides an accurate, easily comprehensible measurement of respiratory induced HR variability.     

Longitudinal investigation of the abstinence violation effect in binge eaters.

This study, guided in part by G. A. Marlatt and J. R. Gordon's (1985) abstinence violation effect (AVE) model, examined whether variability in cognitive and emotional reactions to binges accounts for recurrence of binge eating. Attributional, cognitive, and affective reactions to 2 successive binges, as well as the latencies between each binge and a subsequent binge, were evaluated through a series of structured phone interviews with 50 nonpurging normal-weight female bingers. Reported mood after binging was unrelated to binge latency. However, when Ss made more intense internal, global, and uncontrollable causal attributions for a binge, a subsequent binge followed significantly sooner. Within-subject variations in AVEs across binges prospectively predicted within-subject variations in the speed with which another binge followed. Analyses suggested that cognitive states (e.g., AVE and guilt) evoked by particular events were better predictors of how quickly binging repeats than were stable differences in attributional style. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in intraperson variability in mood.

The experience sampling method and palm-top computers were used to obtain 75–200 randomly timed in situ assessments of 11 mood-related items from 54 Ss over 12–24 days. The variability in the distribution of an S's responses to each item was used as an estimate of intrasubject mood variability. Mood variability was stable across time and across situations. The intercorrelations among the individual item variabilities were also substantial; when the items were combined into a mood variability scale, the coefficient alpha was .84. The stability and internal consistency of mood variability could not be reasonably attributed to similarity in item valences, differences among the Ss in the situations they encountered, response biases, or response errors. It was concluded that mood variability is a stable personal characteristic, but additional analyses suggested that it may be independent from other kinds of intraperson variability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)