The threat of predictable and unpredictable pain: Differential effects on central nervous system processing?

Central nervous system performance is disrupted by pain and by the threat of pain. It is not known whether disruption caused by the threat of pain is dependent on the likelihood of pain occurring. We hypothesised that when a painful stimulus is possible but unpredictable central nervous system performance is reduced, but when the pain is predictable and unavoidable it is not. Sixteen healthy subjects performed a reaction time task during predictable and unpredictable conditions (100% and 50% probability of pain, respectively). Group data showed increased reaction time with the threat of pain by 50 ms (95% Cl 16 to 83 ms) for the predictable condition and 46 ms (95% CI 12 to 80 ms) for the unpredictable condition (p < 0.01 for both), but there was no difference between predictable and unpredictable conditions (p = 0.41). However, individual data showed that there was a differential effect in 75% of subjects (p < 0.05 for all) and that there was a greater effect of predictable pain for some subjects and a greater effect of unpredictable pain for others. Reaction time was related to reported anxiety (r = 0.49, p = 0.02 for both conditions). The predictability of a painful stimulus may have a differential effect on central nervous system performance within individuals, but anxiety about the impending pain appears to be important in determining this effect.

Investigation of the benefits of HIV/AIDS caregiving and relations among caregiving adjustment, benefit finding, and stress and coping variables

The present study explored the nature of benefit finding in HIV/AIDS caregiving, and examined relations among caregiver adjustment, benefit finding, and stress and coping variables. A total of 64 HIV/AIDS caregivers and 46 care recipients completed interviews and questionnaires. First, the study aimed to explore the types of benefits associated with HIV/AIDS caregiving. Content analyses of caregiver responses to an interview question inquiring about gains from caregiving revealed eight benefit themes. Second, the study aimed to examine relations between caregiver adjustment and both benefit finding and stress and coping variables. We hypothesized that number of caregiver reported benefits, social support, challenge and control appraisals, and problem focused coping would be inversely related to poorer adjustment, whereas care recipient reported global distress and illness, caregiver threat appraisal and passive-avoidant emotion-focused coping would be positively associated with poorer adjustment. Correlations indicated that poorer adjustment (measured by global distress, depression, caregiving impact, social adjustment and health status) was positively correlated with care-recipient distress, threat appraisals and passive avoidant coping and inversely correlated with social support, and number of reported benefits. Unexpectedly, problem-focused coping, controllability and challenge appraisals, and care recipient illness were unrelated to adjustment. Third, the study aimed to examine relations between benefit finding and stress and coping variables. Correlations indicated that benefit finding was related to social support use, seeking social support coping and problem-solving coping. Findings indicate that the benefit finding and stress/coping frameworks have utility in guiding research into adaptation to HIV/AIDS caregiving. Results also indicate targets for intervention in the provision of services for HIV/AIDS caregivers.

A case study in specification and implementation testing

Achieving consistency between a specification and its implementation is an important part of software development In previous work, we have presented a method and tool support for testing a formal specification using animation and then verifying an implementation of that specification. The method is based on a testgraph, which provides a partial model of the application under test. The testgraph is used in combination with an animator to generate test sequences for testing the formal specification. The same testgraph is used during testing to execute those same sequences on the implementation and to ensure that the implementation conforms to the specification. So far, the method and its tool support have been applied to software components that can be accessed through an application programmer interface (API). In this paper, we use an industrially-based case study to discuss the problems associated with applying the method to a software system with a graphical user interface (GUI). In particular, the lack of a standardised interface, as well as controllability and observability problems, make it difficult to automate the testing of the implementation. The method can still be applied, but the amount of testing that can be carried on the implementation is limited by the manual effort involved.