In this paper, vibrations and bifurcation of a damped system consists of a mass grounded by linear and nonlinear springs and a nonlinear damper is studied. Nonlinear equation of motion is derived using Newton’s equations. Approximate analytical solutions are obtained using multiple time scales (MTS) method. For free vibration, the approximate analytical results are compared with the numerical i...

objectives: this study was designed to evaluate the psychometric features of the persian version of the fatigue impact scale (fis-p) tool when used in iranian ms patients. methods: 140 ms patients and the equivalent number of healthy controls completed the following assessments: fis-p, fatigue severity scale (fss), sf-36 questionnaire and  the mini-mental state examination (mmse).  results: a s...

background: fatigue, a major cause of disability in individuals with multiple sclerosis (ms), is associated with reduced quality of life. the aim of this study was to evaluate the reliability and reproducibility of the persian version of modified fatigue impact scale (mfis) in iranian patients with ms. methods: this study included 15 subjects with clinically definite ms, 15 hospitalized patient...