Flexible composition and execution of high performance, high fidelity multiscale biomedical simulations.

Multiscale simulations are essential in the biomedical domain to accurately model human physiology. We present a modular approach for designing, constructing and executing multiscale simulations on a wide range of resources, from laptops to petascale supercomputers, including combinations of these. Our work features two multiscale applications, in-stent restenosis and cerebrovascular bloodflow, which combine multiple existing single-scale applications to create a multiscale simulation. These applications can be efficiently coupled, deployed and executed on computers up to the largest (peta) scale, incurring a coupling overhead of 1-10% of the total execution time.

Run-and-tumble particles with hydrodynamics: sedimentation, trapping, and upstream swimming.

We simulate by lattice Boltzmann the nonequilibrium steady states of run-and-tumble particles (inspired by a minimal model of bacteria), interacting by far-field hydrodynamics, subject to confinement. Under gravity, hydrodynamic interactions barely perturb the steady state found without them, but for particles in a harmonic trap such a state is quite changed if the run length is larger than the confinement length: a self-assembled pump is formed. Particles likewise confined in a narrow channel show a generic upstream flux in Poiseuille flow: chiral swimming is not required.

Singular forces and pointlike colloids in lattice Boltzmann hydrodynamics.

We present an accurate method to include arbitrary singular distributions of forces in the lattice Boltzmann formulation of hydrodynamics. We validate our method with several examples involving Stokeslet, stresslet, and rotlet singularities, finding excellent agreement with analytical results. A minimal model for sedimenting particles is presented using the method. In the dilute limit, this model has accuracy comparable to, but computational efficiency much greater than, algorithms that explicitly resolve the size of the particles.

Using packable composites for direct posterior placement.

BACKGROUND: Although dentists have been using resin-based composites successfully to restore posterior teeth in Class II situations for several years, creating a functional, anatomical proximal contact remains a clinical challenge for many clinicians. OVERVIEW: This article presents a step by-step technique for creating a predictable proximal contact using a packable resin-based composite as the restorative material. Using a technique that is similar to that for amalgam will enable the dentist to make a successful transition to using composite as an alternative to amalgam in some posterior teeth. PRACTICE IMPLICATIONS: More patients today are well-informed about dental care and are seeking tooth-colored restorative alternatives. Excellent materials and proven techniques are making the transition from traditional metallic restorations easier and more predictable. With this article, the authors aim to help dentists gain confidence in their technique and enable them to provide this service for their patients.

Full-arch rehabilitation utilizing pressed ceramic veneers and full-coverage crowns.

A variety of all-ceramic systems has been developed to address the limitations exhibited by conventional porcelain-fused-to-metal restorations. The fabrication principles used for pressed ceramic materials requires the application of a vacuum pressure, which results in a restoration with enhanced optical and physical properties. Due to the strength and versatility of these restorations, the indications for the use of pressed all-ceramic restorations continues to expand. This article describes the application of pressed ceramic restorations for comprehensive rehabilitation of the maxillary arch.

The in vivo effects of a prototype diode laser coagulator/vaporizing endoprobe used to perform retinectomy and retinotomy in rabbits.

BACKGROUND AND OBJECTIVE: A pilot study was conducted to evaluate the use of a prototype intraocular carbon-coated diode laser probe for performing single-instrument internal retinotomy and retinectomy. MATERIALS AND METHODS: A 20-gauge endolaser probe was used to perform retinotomies on 10 anesthetized rabbits. Two protocols were examined: one using low power and long duration, and one using high power and short duration. Retinotomies were performed on attached and experimentally detached retinas. RESULTS: Retinotomies were performed in all eyes using both protocols. The edges had photocoagulative effects in all cases. The eyes treated with the longer duration, lower power protocol had scleral damage, whereas the eyes treated with shorter duration, higher power did not. CONCLUSION: Although the diode laser coagulator/cutter may be used for retinotomies, it should be studied further.