Bdellovibrio predation in the presence of decoys:Three-way bacterial interactions revealed by mathematical and experimental analyses

Bdellovibrio bacteriovorus is a small, gram-negative, motile bacterium that preys upon other gram-negative bacteria, including several known human pathogens. Its predation efficiency is usually studied in pure cultures containing solely B. bacteriovorus and a suitable prey. However, in natural environments, as well as in any possible biomedical uses as an antimicrobial, Bdellovibrio is predatory in the presence of diverse decoys, including live nonsusceptible bacteria, eukaryotic cells, and cell debris. Here we gathered and mathematically modeled data from three-member cultures containing predator, prey, and nonsusceptible bacterial decoys. Specifically, we studied the rate of predation of planktonic late-log-phase Escherichia coli S17-1 prey by B. bacteriovorus HD100, both in the presence and in the absence of Bacillus subtilis nonsporulating strain 671, which acted as a live bacterial decoy. Interestingly, we found that although addition of the live Bacillus decoy did decrease the rate of Bdellovibrio predation in liquid cultures, this addition also resulted in a partially compensatory enhancement of the availability of prey for predation. This effect resulted in a higher final yield of Bdellovibrio than would be predicted for a simple inert decoy. Our mathematical model accounts for both negative and positive effects of predator-prey-decoy interactions in the closed batch environment. In addition, it informs considerations for predator dosing in any future therapeutic applications and sheds some light on considerations for modeling the massively complex interactions of real mixed bacterial populations in nature.

Promoting Harmonious Relations and Equitable Well-Being: Peace Psychology and “Intractable” Conflicts

The chapter explores Bar-Tal’s legacy in relation to key concepts, perspectives, and findings that comprise the growing field of peace psychology, specifically the promotion of sustainable peace through the indivisible constructs of harmonious relations and equitable wellbeing. Analyzed through a peace psychology lens, Bar-Tal’s work highlights both the barriers to and bridges for achieving sustainable peace. Central concepts from his work, such as fear, insecurity, and an ethos of conflict, demonstrate key obstacles to fostering harmonious intergroup relations based on social justice. Bar-Tal’s work also identifies processes that can overcome these barriers, which is consistent with peace psychology’s emphasis on the development of constructive responses to violence and conflict. For example, the chapter outlines how confidence-building mechanisms, mutually respectful identities, and reconciliation processes, may help foster an ethos of peace that can be embedded in the structure of societies through peace education. The chapter concludes with implications and suggestions for future research, with a focus on the role of young people in settings of prolonged intergroup division and generational approaches to peacebuilding, as conceptualized through a peace psychology lens.

Predictors of numeracy performance in undergraduate psychology, nursing and medical students

Psychology, nursing and medicine are undergraduate degrees that require students to attain a level of numerical competence for graduation. Yet, the numeracy aspect of these courses is often actively disliked and poorly performed. This study's aim was to identify what factors most strongly predict performance in such courses. Three hundred and twenty-five undergraduate students from these three disciplines were given measures of numeracy performance, maths anxiety, maths attitudes and various demographic and educational variables. From these data three separate path analysis models were formed, showing the predictive effects of affective, demographic and educational variables on numeracy performance. Maths anxiety was the strongest affective predictor for psychology and nursing students, with motivation being more important for medical students. Across participant groups, pre-university maths qualifications were the strongest demographic/educational predictor of performance. The results can be used to suggest ways to improve performance in students having difficulty with numeracy-based modules.