The power prior has been widely used in many applications covering a large number of disciplines. The power prior is intended to be an informative prior constructed from historical data. It has been used in clinical trials, genetics, health care, psychology, environmental health, engineering, economics, and business. It has also been applied for a wide variety of models and settings, both in the experimental design and analysis contexts. In this review article, we give an A to Z exposition of the power prior and its applications to date. We review its theoretical properties, variations in its formulation, statistical contexts for which it has been used, applications, and its advantages over other informative priors. We review models for which it has been used, including generalized linear models, survival models, and random effects models. Statistical areas where the power prior has been used include model selection, experimental design, hierarchical modeling, and conjugate priors. Prequentist properties of power priors in posterior inference are established and a simulation study is conducted to further examine the empirical performance of the posterior estimates with power priors. Real data analyses are given illustrating the power prior as well as the use of the power prior in the Bayesian design of clinical trials.

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Background Transwomen have an increased risk of HIV acquisition compared with other adults. Drug–drug interactions between pre-exposure prophylaxis (PrEP) and gender-affirming therapy are cited as a reason for poor PrEP uptake among transwomen. We evaluated plasma tenofovir and emtricitabine pharmacokinetics and their active intracellular anabolites, tenofovir-diphosphate and emtricitabine-triphosphate, in transwomen receiving feminizing hormones. Methods We enrolled HIV-negative transwomen (≥19 years) not receiving PrEP. Participants took oral tenofovir disoproxil fumarate/emtricitabine 300/200 mg daily for 14 days. Plasma was collected at 0 h (pre-dose), 0.5, 1, 2, 3, 4, 6, 8 and 12 h on day 14 post-tenofovir disoproxil fumarate/emtricitabine dose. The plasma AUC0–24 was calculated using the trapezoidal rule and compared with historical HIV-negative cisgender adults as geometric mean ratios (GMRs, 90% CI). Secondarily, tenofovir-diphosphate and emtricitabine-triphosphate from PBMCs collected at 0 h and 12 h were reported descriptively as geometric means (90% CI). Clinical trials registration: NCT03270969. Results Among 15 transwomen (mean age 32 years), geometric mean tenofovir and emtricitabine plasma AUC0–24 were lower compared with controls: tenofovir, 2.10 versus 2.76 mg·h/L, GMR 0.76 (0.65–0.90), P = 0.01; emtricitabine, 9.15 versus 10.64 mg·h/L, GMR 0.86 (0.75–0.98), P = 0.07. Tenofovir-diphosphate and emtricitabine-triphosphate concentrations were higher than previously reported in the literature: 167.1 (146.6–190.5) fmol/106 cells and 15.4 (13.8–17.3) pmol/106 cells, respectively. Conclusions We observed lower plasma tenofovir and emtricitabine concentrations in transwomen compared with historical cisgender adults, yet intracellular tenofovir-diphosphate and emtricitabine-triphosphate concentrations were higher than previously reported in PBMCs. Understanding the differences of PrEP pharmacokinetics in plasma and tissue compartments and the resultant impact on efficacy remains important for transwomen.

What is the relationship between war propaganda and nationalism, and what are the effects of each on support for, or participation in, violent acts? This is an important question for international criminal law and ongoing speech crime trials, where prosecutors and judges continue to assert that there is a clear causal link between war propaganda, nationalism, and mass violence. Although most legal judgments hinge on the criminal intent of propagandists, the question of whether and to what extent propaganda and nationalism interact to cause support for violence or participation remains unanswered. Our goal here is to contribute to research on propaganda and nationalism by bridging international criminal law and the behavioral and brain sciences. We develop an experiment conducted with Serbian participants that examines the effects of propaganda as identified in the latest international speech crime trial as causing mass violence, and thereby test hypotheses of expert witness Anthony Oberschall’s theory of mass manipulation. Using principal components analysis and Bayesian regression, we examine the effects of propaganda exposure and prior levels of nationalism as well as other demographics on support for violence, ingroup empathy, and outgroup empathy. Results show that while exposure to war propaganda does not increase justifications of violence, specific types of war propaganda increase ingroup empathy and decrease outgroup empathy. Further, although nationalism by itself is not significant for justifying violence, the interaction of increased nationalism and exposure to violent media is significant for altering group empathies. The implications of these findings are discussed with respect to international criminal law and the cognitive science of nationalism.

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