Use of Signal Representation to Identify Abnormal Motor Unit Potentials in Macro EMG

Macro electromyography (EMG) is a recently described recording technique allowing a nonselective recording of motor unit activity. The pick-up area of the electrode, the cannula of a modified single-fiber electrode, covers the entire motor unit territory. The motor unit potential (MUP) is obtained by averaging the cannula signals that are time locked to a single-fiber action potential. The MUP waveform is relatively insensitive to the position of the electrode within the motor unit. The amplitude of the MUP has been used as a measure of the size of the motor unit and normal values for the individual and median MUP amplitude have been defined.     

Expression of Fas and Fas ligand protein and mRNA in mouse oocytes and embryos

During mammalian embryonic development, abnormal eggs and embryos are eliminated by apoptosis; however, the precise apoptotic pathways remain as yet unidentified. In the present study, expression of Fas and Fas ligand - the proximal members of the death receptor pathway, was evaluated in mouse preimplantation embryos by immunofluorescence and in situ hybridization techniques. Ovulated oocytes were collected from oviducts of cyclic mice on the day of oestrus (day 0), and one-cell, two-cell embryos and eight-cell morulae were collected from oviducts of mated animals on days 1, 2 and 3 of pregnancy, respectively. Blastocysts were flushed from the uterine horns on day 4. Expression of Fas and Fas L mRNAs and proteins was absent from embryos at days 0, 1 and 2. A marked increase in Fas and Fas L mRNA and protein expression was detected in all morphologically normal embryos on day 3 and day 4. In addition, embryos on days 3 and 4 were positive for terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) staining; however, absence of caspase 8 and 3 and intense localization of proliferating cell nuclear antigen confirmed the proliferative status of these embryos. Furthermore, TUNEL staining was absent in postimplantation embryonic sections obtained on day 6. The results of the present studies thus indicate an equilibrium between proliferation and apoptosis in the preimplantation embryo.     

Comparison of Laser and Gas Tungsten Arc Weldments of Stabilized 17wt% Cr Ferritic Stainless Steel

One of the major factors influencing weldability of stabilized 17 wt% Cr ferritic stainless steels is extensive grain coarsening in the fusion zone (FZ) and in the heat affected zone (HAZ). This study aimed at exploiting low heat input characteristics of laser welding to effectively control grain coarsening in the FZ and HAZ of 1.2-mm thick stabilized 17 wt% Cr ferritic stainless steel weldment. The study demonstrated that as compared with gas tungsten arc welding (GTAW), laser welding brought about significant grain refinement in the FZ and HAZ. Laser weldments exhibited superior ductility over their GTA counterparts. An important observation of the study was that, in contrast to GTA weldment, laser weldment was associated with weaker interfaces along columnar grain boundaries in the FZ that served to arrest crack propagation normal to them.     

Pulsed laser deposition of metal films and nanoparticles in vacuum using subnanosecond laser pulses

A study of silver, chromium, stainless-steel, and indium thin films prepared by subnanosecond laser deposition in vacuum is reported. We compare the laser ablation in vacuum at the weak- and tight-focusing conditions of a Ti:sapphire laser beam and analyze the nanoparticles synthesized in the latter case using absorption spectroscopy, x-ray fluorescence, atomic force microscopy, and scanning electron microscopy. Our results show that the nanoparticle formation can be accomplished using long laser pulses under tight-focusing conditions.     

A Fuzzy Min-Max Neural Network Classifier With Compensatory Neuron Architecture

This paper proposes a fuzzy min-max neural network classifier with compensatory neurons (FMCNs). FMCN uses hyperbox fuzzy sets to represent the pattern classes. It is a supervised classification technique with new compensatory neuron architecture. The concept of compensatory neuron is inspired from the reflex system of human brain which takes over the control in hazardous conditions. Compensatory neurons (CNs) imitate this behavior by getting activated whenever a test sample falls in the overlapped regions amongst different classes. These neurons are capable to handle the hyperbox overlap and containment more efficiently. Simpson used contraction process based on the principle of minimal disturbance, to solve the problem of hyperbox overlaps. FMCN eliminates use of this process since it is found to be erroneous. FMCN is capable to learn the data online in a single pass through with reduced classification and gradation errors. One of the good features of FMCN is that its performance is less dependent on the initialization of expansion coefficient, i.e., maximum hyperbox size. The paper demonstrates the performance of FMCN by comparing it with fuzzy min-max neural network (FMNN) classifier and general fuzzy min-max neural network (GFMN) classifier, using several examples     

Special-purpose orthonormal basis functions--application to motor unit action potentials

Signal representation is a useful technique to reduce the dimensionality of biological potentials. Usually the basis components are well-defined mathematical functions. We present a new approach using a basis composed of a set of experimentally measured examples of the potential which is to be represented. The criteria used in selecting these basis potentials are described. Using this technique, motor unit potentials measured by a concentric electromyography needle are represented by a basis having 18 components. This technique was found to require roughly one-third fewer components than Fourier analysis to achieve the same quality of representation.