Prenatal diagnosis of Duchenne muscular dystrophy using single fetal cell in maternal blood

We developed a method that allows prenatal diagnosis of Duchenne muscular dystrophy using a single nucleated erythrocyte (NRBC) isolated from maternal blood. Maternal blood was obtained at 8 to 20 weeks of gestation. NRBCs were separated with Percoll using a discontinuous density gradient method and then collected by micromanipulator under microscopic observation. The entire genome of a single cell amplified by primer extension preamplification (PEP). Sex was determined from a small aliquot of the PEP reaction. After an NRBC was determined to be male and confirmed to be of fetal origin, dystrophin exons 4, 8, 12, 45, 48, 50, and 51 were determined from the same PEP reaction. This diagnostic method using maternal blood is safer than amniocentesis or cordocentesis and can be applied to other X-linked disease.     

Numerical approach to simulate the mechanical behavior of biodegradable structures considering degradation time and heterogeneous stress field

Biodegradable polymers are widely used to manufacture biodegradable devices, such as those used in regenerative medicine. In many cases, nonuniform degradation can arise from nonuniform stress fields. The developed numerical methodology can simulate the mechanical behavior of three-dimensional structures subjected to loads during degradation after a given degradation time, thus providing a valuable tool for pre validation of biodegradable devices. Degradation rate was assumed as linear function of the local von Mises stress. Material model parameters change as degradation proceeds and hydrolytic damage increases. Hence, shear modulus of the neo-Hookean constitutive model was assumed as linear function of hydrolytic damage. The methodology was developed in a finite elements' framework using ABAQUS/Standard. The local hydrolytic damage and the consequent shear modulus evolutions were calculated by means of a user material subroutine. The stress field affects locally the kinetics of degradation and the evolution of hydrolytic damage. Thus, local hydrolytic damage and the material parameter are updated at each time step to recalculate stress and strain fields at the inputted degradation time. The aim of this work was to allow the simulation of biodegradable devices subjected to both mechanical and chemical environments.     

Improvement of border characteristics of jointless track circuit

The track circuit uses the rail as part of the circuit. The purposes of the track circuit are (1) to detect the train, (2) to transmit signals to the train, and (3) to detect rail breaks. There are two types of track circuit. One uses insulation joints at the end of the circuit, and the other is jointless. The insulation joint requires much effort to maintain and control. Furthermore, it is extremely expensive, and uses an insulation material, which is one of the weak points of the rail track. There are some methods for constructing a jointless track circuit, but they have several problems. The biggest one is that the border of the track circuits becomes fuzzy. Another is the interference of multiple track circuit signals. Nevertheless, jointless track circuits have high priority. First, they do not demand an insulation joint and impedance bonds. Second, they are very easy to divide. Jointless track circuits are used for sharp curves where it is impossible to install insulation joints on the Shinkansen line. Also, several conventional lines and private railways use this system. Furthermore, several European high‐speed train systems also use jointless track circuits. Regarding Japan Railway, short‐distance track circuits for level crossing control are jointless, but normal track circuits have insulation joints, because there is a legal restriction on track circuit border ambiguity. To solve this problem, the author worked out a simple jointless track circuit only with induction coils, whose border characteristics are excellent. Furthermore, it does not have a strong frequency characteristic and it can be applied to any frequency. In this paper, a new type of jointless track circuit is proposed and theoretically analyzed, and basic experiments are reported. © 1999 Scripta Technica, Electr Eng Jpn, 127(4): 64–76, 1999     

An anisotropic linear elastic boundary element formulation for masonry wall analysis

This work presents an application of a Boundary Element Method (BEM) formulation for anisotropic body analysis using isotropic fundamental solution. The anisotropy is considered by expressing a residual elastic tensor as the difference of the anisotropic and isotropic elastic tensors. Internal variables and cell discretization of the domain are considered. Masonry is a composite material consisting of bricks (masonry units), mortar and the bond between them and it is necessary to take account of anisotropy in this type of structure. The paper presents the formulation, the elastic tensor of the anisotropic medium properties and the algebraic procedure. Two examples are shown to validate the formulation and good agreement was obtained when comparing analytical and numerical results. Two further examples in which masonry walls were simulated, are used to demonstrate that the presented formulation shows close agreement between BE numerical results and different Finite Element (FE) models.