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1. Med any delayed response to a stimulus or agent
2. Psychol any illusory sensation caused by a stimulus that has ceased



the change in the state of strain of a solid in a constant stressed state. A simple case of the aftereffect can be observed in a cylindrical specimen acted on by a constant tensile force P, as illustrated in Figure 1. With time, the strain in the rod increases, (curve ab), and in the general case there is an increase in both the elastic and the plastic deformation. This phenomenon is called the direct aftereffect. The increase in elastic deformation is a manifestation of the elastic aftereffect, and the increase in plastic deformation indicates creep. If at some moment t1 the load is removed, the specimen is immediately shortened to the extent of the elastic deformation (bd), and then a slow contraction of the specimen with time (de)—the reverse aftereffect—is observed.

Figure 1. The elastic aftereffect in a material

The elastic aftereffect without creep is observed in solids whose stressed state nowhere exceeds the elastic limit, and it is classified as a slow reversible process. The elastic aftereffect is usually due to the nonuniformity of the elastically stressed state of actual solids and to the tendency of the stressed state to equalization. The aftereffect explains the phenomenon of elastic hysteresis. For metals, the elastic aftereffect is small, but in organic substances—such as leather, textile fibers, and plastics—it can be of considerable magnitude.

The plastic aftereffect in materials, or creep, is associated with a substantial change in the molecular or crystalline structure of materials and ultimately is a consequence of atomic rearrangements. Aftereffects are investigated in rheology.


References in periodicals archive ?
Paired t-tests were used to determine whether the aftereffect was significant (i.
This discovery reveals that the Motion Aftereffect illusion is not just a compelling visual oddity: It is caused by neural processes that happen essentially every time we see moving objects.
However, paying attention to a feature not directly concerned with movement apparently does not influence motion aftereffects, Chaudhuri says.
For the multivariate analysis of events, death and the presence of aftereffects were considered to be the main variable outcomes.
In a survey conducted a year after the poisoning, about 38% of the respondents said they were suffering physical aftereffects.
But the aftereffects of the labor dispute industrial products and material are still disrupting the flow of the goods.
The group was formed to support Nguyen Viet and Nguyen Duc, who were born conjoined at the lower halves of their bodies, possibly due to aftereffects of the released defoliant.
It was clear that in many countries people were struggling against the efforts of the dominant culture to force its structure of governance on others, one of the aftereffects of colonization.
Standard theories of how species arise suggest such a possibility: Mating signals diversify as aftereffects of animals' adapting to different environments.
Lucy Liu on the aftereffects of the kiss she shared with Calista Flockhart on Ally McBeal, as quoted in the March issue of Detour
Facilities need to identify not only what went wrong, but also all of the negative aftereffects (which are the damages facilities will seek from defendants in a potential lawsuit).
The aftereffects from exposures to virtual environments have often been evaluated using the Simulator Sickness Questionnaire (SSQ) [1], which was originally devised to evaluate computer-based simulator systems.