Introduction: Deformational plagiocephaly (DP) is cranial flattening on one side of the back of the skull produced by an extrinsic force on the intrinsically normal skull. When the flattening is symmetrical, the deformity is called deformational brachycephaly (DB). In the US, its prevalence has increased since the “Back to Sleep” campaign by the American Association of Pediatrics. Helmet therapy is reported to be effective in improving head deformity by multiple studies, but there are few evidences from Japan. The purpose of this study is to investigate the safety and efficacy of helmet therapy for DP, and the feasibility of introducing this treatment to the clinical setting in Japan. Methods: This was a single-arm, retrospective, nonrandomized study. Data were collected on infants who visited the “Clinic for Baby’s Head Shape” in the National Center for Child Health and Development, Tokyo, Japan, between 2011 and 2014. Improvements in Argenta classification, cranial asymmetry (CA), and cranial vault asymmetry index (CVAI) were evaluated. The relationships between CA and influencing factors were evaluated using a linear mixed-effects model. Results: Three hundred eighty-seven infants (273 boys and 114 girls; average age, 4.7 months) visited the clinic during the period, and 159 patients who completed the helmet therapy were analyzed. There were statistically significant improvements in Argenta classification, CA, and CVAI. Almost all of the parents reported increased sweating and mild skin irritation, but no adverse events necessitated the cessation of helmet therapy, except for one patient with increased sweating. Conclusions: Helmet therapy is safe and effective in treating DP and is feasible to introduce to the clinical setting in Japan. Through the distribution of knowledge regarding the etiology and treatment of head deformity, earlier detection and an evidence-based approach to head deformity are expected in the future.

We develop a lattice Boltzmann (LB) model for immiscible two-phase flow simulations with central moments (CMs). This successfully combines a three-dimensional nonorthogonal CM-based LB scheme [De Rosis, Phys. Rev. E 95, 013310 (2017)2470-004510.1103/PhysRevE.95.013310] with our previous color-gradient LB model [Saito, Abe, and Koyama, Phys. Rev. E 96, 013317 (2017)2470-004510.1103/PhysRevE.96.013317]. Hydrodynamic melt-jet breakup simulations show that the proposed model is significantly more stable, even for flow with extremely high Reynolds numbers, up to O(10^{6}). This enables us to investigate the phenomena expected under actual reactor conditions.

The complex relationships between the flow field and heat transfer phenomena of acoustically levitated droplets under evaporation were investigated. To explain these correlations, binary droplets of ethanol and water were used as test fluids. Immediately after droplet levitation, the droplet external flow field direction was toward the droplet, with a circulating vortex forming near the droplet surface. As evaporation progressed, the external flow transitioned toward the opposite direction, while the circulation vortex expanded. To better understand the transition process of the droplet thermal boundary layer, the heat transfer coefficient time series changes were calculated by assuming that the transitions of the ethanol and water binary droplets occurred in three stages: (1) preferential evaporation of ethanol, (2) transition (evaporation of ethanol and condensation of water), and (3) evaporation and condensation of water. Finally, by comparing the flow field and thermal boundary transitions, the transition mechanism for flow structures and heat transport phenomena of acoustically levitated droplets with evaporation was considered. Our experimental and analytical results provide deeper physical insights into noncontact fluid manipulation and suggest potential future applications, such as in acoustic tweezers and microreactors.

Jet breakup is an important behavior at a core disruptive accident for a sodium-cooled fast reactor. The lattice Boltzmann (LB) method is adopted to simulate the jet breakup behavior. The Multiple-Relaxation Time (MRT) scheme is introduced into the existing three-dimensional 19-velocity (D3Q19) LB model for immiscible two-phase flow to enhance the numerical stability for low kinematic viscosity. The simulation results show that the present LB model using MRT enables to simulate the jet breakup behavior, where the kinematic viscosity is of the order of 10 -3 . The velocity field and interfacial shape are compared with the experimental result using PIV and Laser-Induced Fluorescence (LIF). The interfacial instability and fragmentation behavior of the jet can be also simulated. Comparison of the LB simulation with experimental data shows that the time series of jet leading edge can be simulated within an error of around 10%.

When boiling occurs in a liquid flow field, the phenomenon is known as forced-convection boiling. We numerically investigate such a boiling system on a cylinder in a flow at saturated conditions. To deal with the complicated liquid-vapor phase-change phenomenon, we develop a numerical scheme based on the pseudopotential lattice Boltzmann method (LBM). The collision stage is performed in the space of central moments (CMs) to enhance numerical stability for high Reynolds numbers. The adopted forcing scheme, consistent with the CM-based LBM, leads to a concise yet robust algorithm. Furthermore, additional terms required to ensure thermodynamic consistency are derived in a CM framework. The effectiveness of the present scheme is successfully tested against a series of boiling processes, including nucleation, growth, and departure of a vapor bubble for Reynolds numbers varying between 30 and 30 000. Our CM-based LBM can reproduce all the boiling regimes, i.e., nucleate boiling, transition boiling, and film boiling, without any artificial input such as initial vapor phase. We find that the typical boiling curve, also known as the Nukiyama curve, appears even though the focused system is not the pool boiling but the forced-convection system. Also, our simulations support experimental observations of intermittent direct solid-liquid contact even in the film-boiling regime. Finally, we provide quantitative comparison with the semi-empirical correlations for the forced-convection film boiling on a cylinder on the Nu-Ja diagram.