Argumentation Models for Usability Problem Analysis in Individual and Collaborative Settings

Consolidating usability problems (UPs) from problem lists from several users can be a cognitively demanding task for evaluators. It has been suggested that collaboration between evaluators can help this process. In an attempt to learn how evaluators make decisions in this process, the authors studied what justification evaluators give for extracting UPs and their consolidation when working both individually and collaboratively. An experiment with eight novice usability evaluators was carried out where they extracted UPs and consolidated them individually and then collaboratively. The data were analyzed by using conventional content analysis and by creating argumentation models according to the Toulmin model. The results showed that during UP, extraction novice usability evaluators could put forward warrants leading to clear claims when probed but seldom added qualifiers or rebuttals. Novice usability evaluators could identify predefined criteria for a UP when probed and this could be acknowledged as a backing to warrants. In the individual settings, novice evaluators had difficulty in presenting claims and warrants for their decisions on consolidation. Although further study is needed, the results of the study indicated that collaborating pairs had a tendency to argue slightly better than individuals. Through the experiment novice evaluators’ reasoning patterns during problem extraction and consolidation as well as during their assessment of severity and confidence could be identified.     

Teratogenesis by retinoic acid analogs positively correlates with elevation of retinoic acid receptor-beta 2 mRNA levels in treated embryos

The concentration/effect relationship of bunazosin, a selective alpha-1-adrenoceptor antagonist of the quinazoline class, was established in hypertensive patients after a first dose of bunazosin and after 8 weeks of chronic dosing. The study was part of a placebo controlled, multicenter dose-finding trial with parallel group design. After a wash-out period and a 2-week placebo run-in phase, each 4 patients received either placebo, 3 mg, 6 mg or 12 mg bunazosin o.d. in a slow-release formulation. Concentration/effect analysis based on a sigmoidal Emax-model and the drop in the mean arterial blood pressure application of this model was feasible in 9/11 patients. The EC50 after the first dose was 4.6 +/_ 2.0 ng/ml and increased to 9.1 +/- 7.3 ng/ml at steady-state. The decrease in the average of the responsiveness parameter was mainly due to about three-fold, right-shift in the concentration/effect curves at steady-state in 3 patients, the remaining patients showed no or considerably lesser changes of the EC50. Whereas a significant correlation was observed between the pretreatment mean arterial blood pressure and the height of the maximal effect under bunazosin, no relationship appears between the bunazosin dose, the resulting plasma levels at trough and the corresponding effect.     

Controlled-Release Multiple-Units and Single-Unit Doses a Literature Review

The strong influence exerted by the greatly varying normal gastrointestinal functions on the therapeutic value of a controlled-release single-unit dose is elucidated by a review of the literature. In this setting, the multiple-units dose comprising hundreds of mini-depots presents a highly preferable alternative which is due to a greater predictability and reproducibility of its therapeutic effect as well as a lowered risk of side effects.