Electron Dephasing in Mesoscopic Metal Wires

The low-temperature behavior of the electron phase coherence time, $\tau_{\phi}$, in mesoscopic metal wires has been a subject of controversy recently. Whereas theory predicts that $\tau_{\phi}(T)$ in narrow wires should increase as $T^{-2/3}$ as the temperature $T$ is lowered, many samples exhibit a saturation of $\tau_{\phi}$ below about 1 K. We review here the experiments we have performed recently to address this issue. In particular we emphasize that in sufficiently pure Ag and Au samples we observe no saturation of $\tau_{\phi}$ down to our base temperature of 40 mK. In addition, the measured magnitude of $\tau_{\phi}$ is in excellent quantitative agreement with the prediction of the perturbative theory of Altshuler, Aronov and Khmelnitskii. We discuss possible explanations why saturation of $\tau_{\phi}$ is observed in many other samples measured in our laboratory and elsewhere, and answer the criticisms raised recently by Mohanty and Webb regarding our work.Comment: 14 pages, 3 figures; to appear in proceedings of conference "Fundamental Problems of Mesoscopic Physics", Granada, Spain, 6-11 September, 200

Subacromial impingement syndrome and lateral epicondylalgia in tennis players

The purpose of this paper is to review the literature pertaining to subacromial impingement syndrome and lateral epicondylalgia (LE) in tennis players. The mechanisms of joint and muscular imbalances that lead to functional impingement of the shoulder joint may impair the stabilization and power function of the shoulder resulting in overcompensation of the wrist extensors during the tennis swing. This may contribute to microtrauma at the soft tissue structures at the lateral epicondyle thus causing symptoms of LE. Recent interest in the regional interdependence model as well as case studies published in the literature suggests that the relationship of proximal or distal joints should not be overlooked. Compensatory strategies at the distal upper extremity due to changes at the shoulder may overload smaller muscles in the forearm which cannot safely handle the extra stress, especially under repetitive conditions. Conditions of the shoulder and elbow that were previously considered to be independent, specifically subacromial impingement syndrome and lateral epicondylalgia, need to be critically reexamined in the context of regional interdependence given the potential association between the conditions. Specific studies examining the muscle and joint characteristics of the shoulder and elbow are needed as they relate to subacromial impingement syndrome and LE. Anatomic adaptations and biomechanical alterations in the upper extremity could result in abnormal stress loads and microtrauma at the shoulder and lateral elbow