Received 12/26/2000; revised 2/1/2001; accepted 2/9/2001. For correspondence or reprints contact: Shyh-Jen Wang, M.D., Department of Nuclear Medicine, Taichung Veterans General Hospital, 160, Sec. 3, Taichung Harbor Road, Taichung 407, Taiwan, R.O.C. Tel: (886)4-23741349, Fax: (886)4-23741348, E-mail: [email protected] Background: Scintigraphic techniques using gammaemitting radionuclid...

The tensors of curvature play an important role in differential geometry. In surface theory (1990), it is determined by the derivative of unit normal vectors of tangent spaces of the underlying surface. However every geometric object in computation is a discrete model. We can only approximate them. In estimating the curvature on polyhedral surfaces, how to approximate normal vectors is a crucia...

At present, likelihood ratios for two-level models are determined with the use of a normal kernel estimation procedure when the between-group distribution is thought to be non-normal. An extension is described for a two-level model in which the between-group distribution is very positively skewed and an exponential distribution may be thought to represent a good model. The theoretical likelihoo...