The oxidation of As(III) to As(V) by K-birnessite was examined at different temperatures, pHs, and birnessite/As(III) ratios. Experiments ranged in duration from 5 to 64 hr, and solution and solid products were determined at several intervals. All experiments showed that the reaction produced large amounts of K+ to solution and very little Mn2+. As(V) was released to solution and incorporated into the K-birnessite. The oxidation was initially rapid and then slowed. The oxidation of As(III) was probably facilitated initially by autocatalytic Mn-As(V) reactions occurring mostly in the interlayer, in which large amounts of As(V) and K+ could be easily released to solution. The reaction also slowed when interlayer Mn was exhausted by forming Mn-As(V) complexes. Mn(IV) could only be acquired from the octahedral sheets of the birnessite. The two-stage reaction process proposed here depended on the layered structure of birnessite, the specific surface, and presence of exchangeable cations in K-birnessite.

The Wisconsin Twin Project comprises multiple longitudinal studies that span infancy to early adulthood. We summarize recent papers that show how twin designs with deep phenotyping, including biological measures, can inform questions about phenotypic structure, etiology, comorbidity, heterogeneity, and gene–environment interplay of temperamental constructs and mental and physical health conditions of children and adolescents. The general framework for investigations begins with rich characterization of early temperament and follows with study of experiences and exposures across childhood and adolescence. Many studies incorporate neuroimaging and hormone assays.

We read with interest the recent editorial, “The Hennepin Ketamine Study,” by Dr. Samuel Stratton commenting on the research ethics, methodology, and the current public controversy surrounding this study.1 As researchers and investigators of this study, we strongly agree that prospective clinical research in the prehospital environment is necessary to advance the science of Emergency Medical Services (EMS) and emergency medicine. We also agree that accomplishing this is challenging as the prehospital environment often encounters patient populations who cannot provide meaningful informed consent due to their emergent conditions. To ensure that fellow emergency medicine researchers understand the facts of our work so they may plan future studies, and to address some of the questions and concerns in Dr. Stratton’s editorial, the lay press, and in social media,2 we would like to call attention to some inaccuracies in Dr. Stratton’s editorial, and to the lay media stories on which it appears to be based.

Ho JD, Cole JB, Klein LR, Olives TD, Driver BE, Moore JC, Nystrom PC, Arens AM, Simpson NS, Hick JL, Chavez RA, Lynch WL, Miner JR. The Hennepin Ketamine Study investigators’ reply. Prehosp Disaster Med. 2019;34(2):111–113

Objectives: Caregivers of youth with heavy prenatal alcohol exposure report impaired communication, which can significantly impact quality of life. Using data collected as part of the Collaborative Initiative on Fetal Alcohol Spectrum Disorders (CIFASD), we examined whether cognitive variables predict communication ability of youth with histories of heavy prenatal alcohol exposure. Methods: Subjects (ages 10–16 years) comprised two groups: adolescents with heavy prenatal alcohol exposure (AE) and non-exposed controls (CON). Selected measures of executive function (NEPSY, Delis-Kaplan Executive Function System), working memory (CANTAB), and language were tested in the child, while parents completed communication ratings (Vineland Adaptive Behavior Scales – Second Edition). Separate multiple regression analyses determined which cognitive domains predicted communication ability. A final, global model of communication comprised the three cognitive models. Results: Spatial Working Memory and Inhibition significantly contributed to communication ability across groups. Twenty Questions performance related to communication ability in the CON group only while Word Generation performance related to communication ability in the AE group only. Effects remained significant in the global model, with the exception of Spatial Working Memory. Conclusions: Both groups displayed a relation between communication and Spatial Working Memory and Inhibition. Stronger communication ability related to stronger verbal fluency in the AE group and Twenty Questions performance in the CON group. These findings suggest that alcohol-exposed adolescents may rely more heavily on learned verbal storage or fluency for daily communication while non-exposed adolescents may rely more heavily on abstract thinking and verbal efficiency. Interventions aimed at aspects of executive function may be most effective at improving communication ability of these individuals. (JINS, 2018, 24, 1026–1037)

A series of laboratory experiments was conducted to study the formation of internal boluses through the run up of periodic internal wave trains on a uniform slope/shelf topography in a two-layer stratified fluid system. In the experiments, the forcing parameters of the incident waves (wave amplitude and frequency) are varied for constant slope angle and layer depths. Simultaneous particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) measurements are used to calculate high resolution, two-dimensional velocity and density fields. Over the range of wave forcing conditions, four bolus formation types were observed: backward overturning into a coherent bolus, top breaking into a turbulent bolus, top breaking into a turbulent surge and forward breaking into a turbulent surge. Wave forcing parameters, including a wave Froude number $Fr$, a wave Reynolds number $Re$ and a wave steepness parameter $ka_{0}$, are used to relate initial wave forcing to a dominant bolus formation mechanism. Bolus characteristics, including the bolus propagation speed and turbulent components, are also related to wave forcing. Results indicate that for $Fr>0.20$ and $ka_{0}>0.40$, the generated boluses become more turbulent in nature. As wave forcing continues to increase further, boluses are no longer able to form.