An improved discharge technique for excimer lasers

The further development of discharge excimer lasers depends upon a better degree of control over the discharge stability. A problem is the large difference between the breakdown and steady-state voltage which requires a time dependent impedance of the power circuit. Further the large attachment rates of halogens like HCl, causing electric field disturbances require a short rise time of the applied current pulse. A large effort has been expended towards this goal by researchers since the early development of discharge excimer lasers

Globalisation, the World Trade Organisation and the implications for developing countries

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Infeksie in sale vir pasgeborenes in die Karl Bremer-Hospitaal

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An anatomico -physiological Principle governing the direction of the gastro-intestinal mucosal folds during life

The mucosa, being the innermost layer of the gastrointestinal tract, is intimately concerned with digestion and absorption, and, presumably, also with the transport of intestinal contents. In anatomical, physiological and motility studies, possible movements of the mucosa and its folds are neither considered nor investigated. Dogmatic statements about the direction of the folds are often made. Radiologists have long been aware of mucosal movements, but after the fundamental work of Forssell, no further views have been put forward. Radiological procedures have been used to investigate the normal, macroscopic, physiological movements of mucosal folds. A general rule follows. Normally, when the intestine is filled, but inactive, the folds are circular; when the walls contract, the folds change in direction, to become longitudinal. This phenomenon is confirmed by in vivo baboon studies and elucidated by wire spirals. It is seen to be an inherent characteristic of 'peristaltic' and 'segmental' contractions. In this manner longitudinal mucosal furrows are formed simultaneously with the contraction wave of the walls, thus facilitating transit. Were this not so, peristalsis would be an ineffective mechanism, with contraction waves acting against the resistance of circular folds.S. Afr. Med. J., 48, 441 (1974)