in this paper, we show that every element of a discrete module is a sum of two units if and only if its endomorphism ring has no factor ring isomorphic to $z_{2}$. we also characterize unit sum number equal to two for the endomorphism ring of quasi-discrete modules with finite exchange property.

In motor neurone disease changes in the functional properties of motor units, including the surface voltage, latency, conduction velocity, and response to repetitive stimulation, were investigated. Progression was marked by motor unit loss, increase in the proportion of larger motor unit potentials, and inclusion of motor unit potentials larger than normal in the remaining motor unit population...

Objectives: To study the correlation between anatomical parameters and EMG signals by means of simulations. Methods: A mathematical model of the electrical activity from muscle ®bres and motor units has been developed. The electrical ®elds around the muscle ®bres are simulated using a line source model. The model permits the simulation of single muscle ®bre action potentials obtained by SFEMG, ...

Two electrophysiological methods have been described for estimating the number of motor units (MU) in a muscle. The methods are based on the original methods of Mc Comas and others, which involve dividing the maximum compound potential (MCP) of muscle evoked by supramaximal electrical stimulation of nerve by a mean motor unit potential (MMUP). The important modifications in the methods are the ...

Weakness and atrophy are clinical signs that accompany muscle denervation resulting from motor neuron disease, peripheral neuropathies, and injury. Advances in our understanding of the genetics and molecular biology of these disorders have led to the development of therapeutic alternatives designed to slow denervation and promote reinnervation. Preclinical in vitro research gave rise to the nee...

Weakness and atrophy are clinical signs that accompany muscle denervation resulting from motor neuron disease, peripheral neuropathies and injury. Advances in our understanding of the genetics and molecular biology of these disorders have led to the development of therapeutic alternatives designed to slow denervation and promote reinnervation. Preclinical in vitro research gave rise to the need...

The technique of the macro-EMG was used to estimate the number of motor units in the tibialis anterior muscles of healthy subjects in a wide range of ages, and of patients with myasthenia gravis and patients with amyotrophic lateral sclerosis or spinal muscular atrophy. The results obtained suggest a decrease in the number of motor units in the tibialis anterior muscle with increasing age in no...

The purpose of the study was to quantify the influence of selected motor unit properties and patterns of activity on amplitude cancellation in the simulated surface electromyogram (EMG). The study involved computer simulations of a motor unit population with physiologically defined recruitment and rate coding characteristics that activated muscle fibers whose potentials were recorded on the ski...