Precision edge contrast and orientation estimation

The contrast and orientation estimation accuracy of several edge operators that have been proposed in the literature is examined both for the noiseless case and in the presence of additive Gaussian noise. The test image is an ideal step edge that has been sampled with a square-aperture grid. The effects of subpixel translations and rotations of the edge on the performance of the operators are studied. It is shown that the effect of subpixel translations of an edge can generate more error than moderate noise levels. Methods with improved results are presented for Sobel angle estimates and the Nevatia-Babu operator, and theoretical noise performance evaluations are also provided. An edge operator based on two-dimensional spatial moments is presented. All methods are compared according to worst-case and RMS error in an ideal noiseless situation and RMS error under various noise levels     

Subpixel measurements using a moment-based edge operator

Recent results in precision measurements using computer vision are presented. An edge operator based on two-dimensional spatial moments is given. The operator can be implemented for virtually any size of window and has been shown to locate edges in digitized images to a twentieth of a pixel. This accuracy is unaffected by additive or multiplicative changes to the data values. The precision is achieved by correcting for many of the deterministic errors caused by nonideal edge profiles using a lookup table to correct the original estimates of edge orientation and location. This table is generated using a synthesized edge which is located at various subpixel locations and various orientations. The operator is extended to accommodate nonideal edge profiles and rectangularly sampled pixels. The technique is applied to the measurement of imaged machined metal parts. Theoretical and experimental noise analyses show that the operator has relatively small bias in the presence of noise     

Effects of cigarette smoking on electrodermal orienting reflexes to stimulus change and stimulus significance

Skin conductance responses (SCRs) evoked by novel, signal, and frequent tone stimuli were measured in 20 male heavy smokers and 10 male nonsmokers over two sessions. All smokers abstained from smoking for 12 hr prior to each session. Half of the smokers smoked a cigarette of their preferred brand prior to SCR measurement in the first session, whereas the remaining smokers smoked in the second session. Nonsmokers did not smoke. Results combined across the two sessions indicated that abstinence was associated with selective depression of SCRs to the novel tone. Separate analyses of results from each session revealed that, in the second session, SCRs to both novel and signal tones were depressed in abstinent smokers, partially replicating previous findings. By contrast, first session results showed no significant effects of smoking or abstinence. Results were interpreted in terms of nicotine's effects on nonspecific arousal, with some reservations.     

"Loss of control" in alcoholism and drug addiction: A neuroscientific interpretation.

Considerable neurological evidence indicates that the prefrontal cortex mediates complex "executive" functions including behavioral autonomy and self-control. Given that impairments of self-control are characteristic of alcoholism and other drug addictions, frontal lobe dysfunction may play a significant role in such compulsive behaviors. Consistent with this idea, recent research using brain imaging, neuropsychological testing, and other techniques has revealed that the frontal lobes are particularly vulnerable to the acute and chronic effects of addictive drugs, especially alcohol and cocaine. Evidence implicating a hyperdopaminergic mechanism of acute and chronic drug-induced frontal lobe dysfunction and interactions with premorbid factors and stress are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of cigarette smoking and smoking deprivation on Wisconsin Card Sorting Test performance.

Wisconsin Card Sorting Test (WCST) performance was assessed in 24 heavy smokers and 12 nonsmokers recruited from universities in the US and Japan. Half of the smokers performed the WCST after abstaining from tobacco for 12 hrs, whereas the remaining smokers smoked a cigarette of their preferred brand immediately before the test. Nonsmokers did not smoke. The WCST was administered by computer, first with standard instructions and then a 2nd time with abbreviated instructions that specified the 3 sorting criteria. Results from the 2nd run indicated that abstinent smokers made significantly more perseverative responses and errors than did nonsmokers or smoking smokers. Results expand on previous findings of effects of smoking deprivation on human cognitive performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Drug addiction as a physical disease: the role of physical dependence and other chronic drug-induced neurophysiological changes in compulsive drug self-administration

The effects of breast-feeding and supplementation practices on recent diarrhoea occurrence and stunted growth are modelled using logistic regression techniques. Data from the Demographic and Health Survey of Bolivia, 1989, show that, among children aged 3-36 months at the date of interview, the benefits of breast-feeding to child health were most pronounced among children living in rural poverty. Reduced breast-feeding among these children increased the likelihood of diarrhoea and stunted growth. In addition, the introduction of solid foods to currently lactating infants negatively influenced child health.     

A unique instructional tool for visualizing equipotentials and itsuse in an introductory fields course

Charge Master, an IBM PC-compatible software package that aids in visualizing equipotentials produced by systems of point charges, is described. It accomplishes this via an educational game and an option that plots equipotentials. An assignment designed to accompany the software and its use in an introductory EM fields course are also described. The software has been well received by students     

Cognition, emotion, and the alcohol–aggression relationship: Comment on Giancola (2000).

P. R. Giancola's (see record 2000-02949-013) thesis that the alcohol-aggression relationship can be explained by alcohol-induced disruption of executive cognitive functions mediated by the prefrontal cortex is critically examined. At moderate doses, alcohol has been reported to increase aggression in animals as diverse as fish, rats, cats, monkeys, and humans. Although alcohol depresses prefrontal cortex activity and disrupts executive cognitive performance in humans, alcohol's anxiolytic actions, and its disinhibiting effects on subcortical structures implicated in anger and aggression, may be at least as important as the higher cognitive functions cited by Giancola in accounting for the alcohol-aggression relationship. Other drugs that alter prefrontal cortex activity have also been reported to influence aggressive responding in humans and other animals, and implications of this are briefly discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)