PURPOSE To describe the rationale behind elliptical and other transition designs used with the excimer laser. SETTING Casey Eye Institute, Oregon Health Sciences University, Portland, Oregon, USA. METHODS Ablation zone designs were analyzed for the number of transition points for myopia and hyperopia. The advantages and disadvantages of elliptical transition zones are demonstrated graphical...

BACKGROUND A standard contrast enema for Hirschsprung's disease can sometimes be inconclusive in delineating a transition zone especially in neonates and infants. The aim of this study was to determine the utility and diagnostic accuracy of a plain abdominal radiograph transition zone (PARTZ) in predicting the level of aganglionosis. METHODS A prospective observational study of neonates and i...

The Sungun porphyry copper deposit is located in northwestern Iran and is associated with diorite/granodiorite to quartz-monzonite of Miocene age, which intruded Eocene volcanosedimentary and Cretaceous carbonate rocks. Copper mineralization was accompanied by both potassic and phyllic alteration. Three main mineralization related alteration episodes (potassic, transition, and phyllic alteratio...

Oxidase activities were investigated within the cross-section of walnut trunk in relation to the brown staining of heartwood, especially in the transition zone where the colour change occurs. The distribution of peroxidase activity was investigated using 3,3'-diaminobenzidine (DAB) or guaiacol as a substrate. Generally, the highest activity was found in the cambial zone and in the middle sapwoo...

In the transition zone between aquifers and basal aquitards, the perchloroethenepools are more recalcitrant than those elsewhere in the aquifer. The aim of this study is to demonstrate that the transition zone is an ecotone where the biodegradation of chloroethenes from aged-pools of perchloroethene is favored. A field site was selected where an aged pool exists at the bottom of a transition zo...

Cilia hoist dust out of the lungs, propel sperm toward the egg, and enable us to catch the scent of fresh coffee. The structures also help some cells attach to their surroundings, Schouteden et al. reveal (1). A cilium is built around the axoneme, an internal shaft of microtubules that sprouts from a structure known as the basal body. Between the axoneme and the basal body lies the transition z...