Experimental influence of pH on the early life-stages of sea urchins I: different rates of introduction give rise to different responses

Many early life-stage response studies to ocean acidification utilize gametes/offspring obtained from ambient-sourced parents, which are then directly introduced to experimentally altered seawater pH. This approach may produce a stress response potentially impacting development and survival. Hence, this study determined whether this approach is suitable by subjecting embryos/larvae to different rates of introduction to lowered seawater pH to assess larval success under acute and staggered experimental pH scenarios. Embryos and 4-armed larvae of the sea urchin Psammechinus miliaris were introduced to pH conditions, widely used in ocean acidification studies, from ambient conditions utilizing 380, 470, 560, 700 and 840 ppm CO2 changed at incremental steps at two rates: fast (every 3rd hour) or slow (every 48th hour). Direct transfers from ambient to low seawater pH gave rise to dramatic negative impacts (smaller size and low survival), but slower rates of introductions gave rise to lesser negative responses (low survival). There was no treatment effect on settled juveniles. Fast introductions utilized in many studies are likely not ideal approaches when assessing pre-settlement larval developmental responses. Therefore, careful consideration of the pattern of response is needed when studies report the responses of offspring, derived from ambient conditions, introduced directly to forecasted ocean acidification conditions

Defining Haptic Experience: Foundations for Understanding, Communicating, and Evaluating HX

Haptic technology is maturing, with expectations and evidence that it will contribute to user experience (UX). However, we have very little understanding about how haptic technology can influence people’s experience. Researchers and designers need a way to understand, communicate, and evaluate haptic technology’s effect on UX. From a literature review and two studies – one with haptics novices, the other with expert hapticians – we developed a theoretical model of the factors that constitute a good haptic experience (HX). We define HX and propose its constituent factors: design parameters of Timeliness, Density, Intensity, and Timbre; the cross-cutting concern of Personalization; usability requirements of Utility, Causality, Consistency, and Saliency; and experiential factors of Harmony, Expressivity, Autotelics, Immersion, and Realism as guiding constructs important for haptic experience. This model will help guide design and research of haptic systems, inform language around haptics, and provide the basis for evaluative instruments, such as checklists, heuristics, or questionnaires.We acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC), [funding reference number 2019-06589

Comparison of dose-finding designs for narrow-therapeutic-index drugs: Concentration-controlled vs. dose-controlled trials

This study compared the performances of randomized dose-controlled trials (DCTs) with those of concentration-controlled trials (CCTs) in dose finding for drugs with narrow therapeutic indexes. A simulation-based study was performed for a hypothetical immunosuppressant agent with two clinical end points. Different scenarios were simulated and analyzed, and three designs were compared: one DCT and two CCTs (a target-equivalent CCT and a variability-equivalent CCT). The DCT was consistently superior to the CCTs in the following aspects: (i) precision and bias reduction in parameter estimates, (ii) precision and bias reduction in the estimate of optimal exposure, (iii) bias reduction in prediction of the estimated therapeutic benefit at estimated optimal exposure, and (iv) bias reduction in prediction of the estimated benefit of therapeutic drug monitoring as compared with fixed dosing. DCT designs are more informative when describing the exposure-response relationship for drugs with narrow therapeutic indexes and provide a better basis for decision making with regard to dosing strategy