Chlorophyll- and anthocyanin-rich cell organelles affect light scattering in apple skin.

Apple skin contains several groups of strongly absorbing cell organelles with pigments that change dynamically in type and concentration during fruit maturation. Chlorophylls and carotenoids, both primarily involved in photosynthesis, are found in the grana of chloroplasts, while anthocyanin vacuolar inclusions (AVIs) accumulate for light protection in red-skinned cultivars. A Mie model describing light scattering by absorbing spherical particles in a non-absorbing medium allowed to theoretically investigate the explicit influence of grana and AVIs on the effective scattering coefficient [Formula: see text] and the absorption coefficient [Formula: see text].

Parallelized Monte Carlo software to efficiently simulate the light propagation in arbitrarily shaped objects and aligned scattering media.

A GPU-based Monte Carlo software (MCtet) was developed to calculate the light propagation in arbitrarily shaped objects, like a human tooth, represented by a tetrahedral mesh. A unique feature of MCtet is a concept to realize different kinds of light-sources illuminating the complex-shaped surface of an object, for which no preprocessing step is needed. With this concept, it is also possible to consider photons leaving a turbid media and reentering again in case of a concave object.

Broadband Optical Properties of Milk.

Dairy products play an important role in our daily nutrition. As a turbid scattering medium with different kinds of particles and droplets, each alteration of these components changes the scattering properties of milk. The goal of this work is the determination of the amount of main scattering components, the fat droplets and the casein micelles, by understanding the light propagation in homogenized milk and in raw milk.

Monte Carlo modeling of polarized light propagation: Stokes vs. Jones. Part II.

In this second part of our comparative study inspecting the (dis)similarities between "Stokes" and "Jones," we present simulation results yielded by two independent Monte Carlo programs: (i) one developed in Bern with the Jones formalism and (ii) the other implemented in Ulm with the Stokes notation. The simulated polarimetric experiments involve suspensions of polystyrene spheres with varying size. Reflection and refraction at the sample/air interfaces are also considered.

Monte Carlo modeling of polarized light propagation: Stokes vs. Jones. Part I.

This bipartite comparative study aims at inspecting the similarities and differences between the Jones and Stokes-Mueller formalisms when modeling polarized light propagation with numerical simulations of the Monte Carlo type. In this first part, we review the theoretical concepts that concern light propagation and detection with both pure and partially/totally unpolarized states. The latter case involving fluctuations, or "depolarizing effects," is of special interest here: Jones and Stokes-Mueller are equally apt to model such effects and are expected to yield identical results.

Light propagation in structural anisotropic media in the steady-state and time domains.

The determination of the reduced scattering and absorption coefficients of structural anisotropic turbid semi-infinite media and slabs was investigated in the steady-state and time domains. Forward calculations were performed with a Monte Carlo model that considered both cylindrical scatterers aligned in different directions as well as scatterers that were described by a rotationally symmetric scattering function. Analytical solutions of the isotropic and anisotropic diffusion equations were applied to retrieve the optical properties.

Use of a modified expander during rapid maxillary expansion in adults: an in vitro and finite element study.

Purpose: This preliminary study was performed to evaluate a proposed maxillary expansion treatment method for adults with fused intermaxillary sutures.

Materials And Methods: This study was performed in three Thiel-fixed skulls from older female cadavers with a microimplant-supported expansion screw. This modified expansion screw was mounted on the palatine process with microimplants and activated every 15 to 20 seconds with an activation key until the intermaxillary suture ruptured.

Multiple scattering of polarized light: comparison of Maxwell theory and radiative transfer theory.

For many research areas in biomedical optics, information about scattering of polarized light in turbid media is of increasing importance. Scattering simulations within this field are mainly performed on the basis of radiative transfer theory. In this study a polarization sensitive Monte Carlo solution of radiative transfer theory is compared to exact Maxwell solutions for all elements of the scattering Müller matrix.

Influence of different modeling strategies for the periodontal ligament on finite element simulation results.

Introduction: The finite element method is a promising tool to investigate the material properties and the structural response of the periodontal ligament (PDL). To obtain realistic and reproducible results during finite element simulations of the PDL, suitable bio-fidelic finite element meshes of the geometry are essential.

Methods: In this study, 4 independent coworkers generated altogether 17 volume meshes (3-dimensional) based on the same high-resolution computed-tomography image data set of a tooth obtained in vivo to compare the influence of the different model generation techniques on the predicted response to loading for low orthodontic forces.

Soft-tissue changes after maxillomandibular advancement surgery assessed with cone-beam computed tomography.

Introduction: The purpose of this study was to quantify anteroposterior and transverse facial soft-tissue changes with respect to underlying skeletal movements after maxillomandibular advancements by using cone-beam computed tomography.

Methods: Thirty white patients were treated by maxillomandibular advancements after LeFort I osteotomies and bilateral sagittal split osteotomies. The patients were scanned by using cone-beam computed tomography within 1 week before the surgery, within 1 week after the surgery, and a minimum of 8 weeks postsurgery.

In-vitro results of rapid maxillary expansion on adults compared with finite element simulations.

This study was mainly performed to investigate the effects of high maxillary expansion forces on the skull with fresh and thiel-fixed human skulls. The maxillary suture was not weakened except in one experiment. This study compares the strain measured on the zygomatic process of the skull with the results of a finite element model generated for this purpose.

A downloadable meshed human canine tooth model with PDL and bone for finite element simulations.

Objective: The aim of this study is to relieve scientists from the complex and time-consuming task of model generation by providing a model of a canine tooth and its periradicular tissues for Finite Element Method (FEM) simulations.

Methods: This was achieved with diverse commercial software, based on a micro-computed tomography of the specimen.

Results: The Finite Element (FE) Model consists of enamel, dentin, nerve (innervation), periodontal ligament (PDL), and the surrounding cortical bone with trabecular structure.

Correspondences of hydrostatic pressure in periodontal ligament with regions of root resorption: a clinical and a finite element study of the same human teeth.

Introduction: The main objectives of this study were to generate individual finite element models of extracted human upper first premolars, and to simulate the distribution of the hydrostatic pressure in the periodontal ligament (PDL) of these models for evaluation of the risk of root resorption.

Methods: The individual extracted teeth were from a previous in vivo study that investigated root resorption after application of continuous intrusive forces. The results of experimental examination and simulations were compared on these identical tooth roots.

Stress distribution and displacement analysis during an intermaxillary disjunction--a three-dimensional FEM study of a human skull.

The goal of this study was to contribute to an understanding of how much expansion force is needed during a maxillary expansion (ME) and where bony reaction takes place. A finite element (FE) model of a dry human male skull was generated from CT scans. The FE model, which consists of cortical and cancellous bone and teeth, was loaded with the same force magnitudes, directions and working points as in rapid maxillary expansion (RME).

Periodontal ligament hydrostatic pressure with areas of root resorption after application of a continuous torque moment.

Objective: To evaluate the risk of root resorption, individual finite element models (FEMs) of extracted human maxillary first premolars were created, and the distribution of the hydrostatic pressure in the periodontal ligament (PDL) of these models was simulated.

Materials And Methods: A continuous lingual torque of 3 Nmm and 6 Nmm respectively was applied in vivo to the aforementioned teeth. After extraction, FEMs of these double-rooted teeth were created based on high-resolution microcomputed tomographics (micro CT, voxel size: 35 microns).