Beyond sound: bimodal acoustic calls used in mate-choice and aggression by red-eyed treefrogs.

Airborne sound signals function as key mediators of mate-choice, aggression and other social interactions in a wide range of vertebrate and invertebrate animals. Calling animals produce more than sound, however. When displaying on or near a solid substrate, such as vegetation or soil, they also unavoidably excite substrate vibrations because of the physics of sound production and of acoustic propagation, and these vibrations can propagate to receivers. Despite their near ubiquity, these vibrational signal components have received very little research attention and in vertebrates it is unknown whether they are relevant to mate-choice, an important driver of evolutionary divergence. Here, we show that female red-eyed treefrogs are more than twice as likely to choose a male mating call when airborne sound is paired with its corresponding substrate vibrations. Furthermore, males of the same species are more aggressive towards and display a greater range of aggressive behaviors in response to bimodal (sound and vibration) versus unimodal (sound or vibration alone) calls. In aggressive contexts, at least, air- and substrate-borne signal components function non-redundantly. These results are a clear demonstration that vibrations produced by a calling animal can function together with airborne sound to markedly enhance the function of a signal. If this phenomenon proves widespread, this finding has the potential to substantially influence our understanding of the function and evolution of acoustic signals.

"Practice so that the skill does not disappear": mixed methods evaluation of simulator-based learning for midwives in Uganda.

BACKGROUND: Postpartum hemorrhage and neonatal asphyxia are leading causes of maternal and neonatal mortality, respectively, that occur relatively rarely in low-volume health facilities in sub-Saharan Africa. Rare occurrence of cases may limit the readiness and skills that individual birth attendants have to address complications. Evidence suggests that simulator-based training and practice sessions can help birth attendants maintain these life-saving skills; one approach is called "low-dose, high-frequency" (LDHF). The objective of this evaluation is to determine the facilitating factors and barriers to participation in LDHF practice, using qualitative and quantitative information. METHODS: A trial in 125 facilities in Uganda compared three strategies of support for LDHF practice to improve retention of skills in prevention and treatment of postpartum hemorrhage and neonatal asphyxia. Birth attendants kept written logs of their simulator-based practice sessions, which were entered into a database, then analyzed using Stata to compare frequency of practice by the study arm. The evaluation also included 29 in-depth interviews and 19 focus group discussions with birth attendants and district trainers. Transcripts were entered in Atlas.ti software for coding, then analyzed using content analysis to identify factors that motivated or discouraged simulator-based practice. RESULTS: Practice log data indicated that simulator-based practice sessions occurred more frequently in facilities where one or two practice coordinators helped schedule and lead the practice sessions and in health centers compared to hospitals. The qualitative data suggest that birth attendants who practiced more were motivated by a desire to maintain skills and be prepared for emergencies, external recognition, and establishing a set schedule. Barriers to consistent practice included low staffing levels, heavy workloads, and a sense that competency can be maintained through routine clinical care alone. Some facilities described norms around continuing education and some did not. CONCLUSIONS: Designating practice coordinators to lead their peers in simulator-based practice led to more consistent skills practice within frontline health facilities. Ongoing support, scheduling of practice sessions, and assessment and communication of motivation factors may help sustain LDHF practice and similar forms of continuing professional development. TRIAL REGISTRATION: Registered with clinicaltrials.gov #NCT03254628 on August 18, 2018 (registered retrospectively).