The best known output-sensitive sequential algorithm for computing the viewshed on a polyhedral terrain from a given viewpoint was proposed by Katz, Overmars, and Sharir 10 , and achieves time complexity O((k + nn(n)) log n) where n and k are the input and output sizes respectively, and () is the inverse Ackermann's function. In this paper, we present a parallel algorithm that is based on the w...

A novel intrinsically decoupled transmit and receive radio-frequency coil element is presented for applications in parallel imaging and parallel excitation techniques in high-field magnetic resonance imaging. Decoupling is achieved by a twofold strategy: during transmission elements are driven by current sources, while during signal reception resonant elements are switched to a high input imped...

background: the aim of this study was to investigate vertebral geometry changes and determine cutoff value of vertebral height to predict fractures. methods: in a cross-sectional study, 280 postmenopausal women recruited .in all subjects bone mineral density and radiog raphy of the lumbar spine performed. lateral radiographs were evaluated for identification of vertebral fractures, using a vali...