A perfectly matched layer (PML) absorbing material composed of a uniaxial anisotropic material is presented for the truncation of finite-difference time-domain (FDTD) lattices. It is shown that the uniaxial PML material formulation is mathematically equivalent to the perfectly matched layer method published by Berenger (see J. Computat. Phys., Oct. 1994). However, unlike Berenger's technique, the uniaxial PML absorbing medium presented in this paper is based on a Maxwellian formulation. Numerical examples demonstrate that the FDTD implementation of the uniaxial PML medium (...) is stable, equal in effectiveness as compared to Berenger's PML medium, while being more computationally efficient. (shrink)

Two studies tested the hypothesis that certain positive emotions speed recovery from the cardiovascular sequelae of negative emotions. In Study 1, 60 subjects (Ss) viewed an initial fear-eliciting film, and were randomly assigned to view a secondary film that elicited: (a) contentment; (b) amusement; (c) neutrality; or (d) sadness. Compared to Ss who viewed the neutral and sad secondary films, those who viewed the positive films exhibited more rapid returns to pre-film levels of cardiovascular activation. In Study 2, 72 Ss (...) viewed a film known to elicit sadness. Fifty Ss spontaneously smiled at least once while viewing this film. Compared to Ss who did not smile, those who smiled exhibited more rapid returns to pre-film levels of cardiovascular activation. We discuss these findings in terms of emotion theory and possible health-promoting functions of positive emotions. (shrink)

Emotions are viewed as having evolved through their adaptive value in dealing with fundamental life-tasks. Each emotion has unique features: signal, physiology, and antecedent events. Each emotion also has characteristics in common with other emotions: rapid onset, short duration, unbidden occurrence, automatic appraisal, and coherence among responses. These shared and unique characteristics are the product of our evolution, and distinguish emotions from other affective phenomena.

This article presents a model of the structure of emotion developed primarily from a consideration of neuropsychological evidence and behavioural data which have bearing on neuropsychological theories. Valence is first considered and highlighted as a defining characteristic of emotion. Next, the use of facial behaviour and autonomic nervous system patterns as defining characteristics of discrete emotions is questioned on empirical and conceptual grounds. The regulation of emotion is considered and proposed to affect the very structure of emotion itself. If there (...) is an invariant pattern of biological activity across different instantiations of the same emotion, it is likely to be found in higher-order associative networks of central nervous system activity, the very same networks that subserve goal-directed behaviour and other cognitive functions. Drawing upon evolutionary considerations, it is argued that what is basic about emotion are the dimensions of approach and withdrawal. The nature of the linkage between such action tendencies and emotion is discussed. (shrink)

What are 'emotions'? This book offers a balanced survey of facts and theory.