We prove a general Borg-type result for reflectionless unitary CMV operators U associated with orthogonal polynomials on the unit circle. The spectrum of U is assumed to be a connected arc on the unit circle. This extends a recent result of Simon in connection with a periodic CMV operator with spectrum the whole unit circle. In the course of deriving the Borg-type result we also use exponential...

ii 3 To my father iii 4 iv 5 Abstract The general aim of the thesis is to answer questions on general and differential aspects of perceived exertion and on the measurement of its intensity variation. Overall perceived exertion is commonly treated as a unidemensional construct. This thesis also explores its multidimensional character. Four empirical studies are summarized (Study I-IV). Psychophy...

The electromyogram recorded from the diaphragm (EMGdi) and parasternal intercostal muscle using surface electrodes (sEMGpara) provides a measure of neural respiratory drive (NRD), the magnitude of which reflects lung disease severity in stable cystic fibrosis. The aim of this study was to explore perception of NRD and breathlessness in both healthy individuals and patients with cystic fibrosis....

We provide a new short proof of the following fact, first proved by one of us in 1998: If two Weyl–Titchmarsh m-functions, mj(z), of two Schrödinger operators Hj = − d2 dx2 + qj , j = 1, 2 in L2((0, R)), 0 < R ≤ ∞, are exponentially close, that is, |m1(z) − m2(z)| = |z|→∞ O(e −2 Im(z)a), 0 < a < R, then q1 = q2 a.e. on [0, a]. The result applies to any boundary conditions at x = 0 and x = R and...

The aim of the study was to determine whether the Borg dyspnoea scale could be a useful and simple marker to predict respiratory muscle weakness in amyotrophic lateral sclerosis (ALS). From April 1997 to 2001, respiratory function was perfomed in 72 patients together with the Borg score in both the upright (uBorg) and supine (sBorg) positions. Mean upright vital capacity (VC) was 81+/-24% predi...