Computer-assisted morphometry of the peripheral nervous system. A diagnostic tool.

A formal systematization of the set of procedures required in peripheral nerve morphometry has been implemented in a computer program, in an attempt to provide an easy-to-handle diagnostic tool in current neuropathological practice. The hardware is composed of an IBM-PC compatible computer and a graphic tablet. Programs are written in BASIC and run in computers compatible with the MS-DOS operating system. The flow of operative steps involved in the morphometric study is controlled by the software. Sequential measurements are also tested for congruence. Nerve fibre measurements are stored in pluri-dimensional matrices for subsequent statistical calculations, i.e. evaluation of size-frequency distribution of nerve fibres and correlation analysis between nerve fibre subcomponents. Stereological estimates of the parenchymal components are also derived. The increase in accuracy achieved using area instead of diameter measurements is stressed. Compared to "dedicated" machines such personal computer-assisted systems exhibit substantial advantages in terms of low cost and flexibility

Influence of the Second-Order Uniaxial Anisotropy on the Dynamical Proprieties of Magnetic Tunnel Junctions

The magnetization dynamics of a ferromagnet can be influenced by the second-order anisotropy contribution when the magnetocrystalline perpendicular anisotropy is of the same order of the out-of-plane demagnetizing field (compensation point). This condition can be fulfilled in magnetic tunnel junctions (MTJs) where the induced interfacial perpendicular anisotropy can be controlled by the thickness of the free layer. This paper describes, within a both micromagnetic and analytical/numerical framework, how switching and self-oscillation of the magnetization are affected by the second order magnetocrystalline anisotropy near the compensation point. We have derived analytical expressions for the switching critical current and the oscillation frequencies that are well reproduced by numerical simulations. Our results can support the design of MTJs for application either in storage and nanoscale signal generators