Characterization and modelling of the hollow beam produced by a real conical lens

The properties of the hollow beam produced by a conical lens are studied in detail. In particular, the impact of a rounded vertex is examined. It is shown that it could lead to drastic changes in the transverse distribution of the hollow beam, determined by the ratio between the transverse size of the incident beam and the size of the blunt area. An adequate choice for this ratio allows us to either minimize the losses or optimize the distribution symmetry.Comment: 13 pages, 10 figures, submitted to Optics Communication

Dynamic and static measures of growth among pre- and postmenarcheal females in rural Bangladesh

Height and weight for age and height and weight velocity are examined in a sample of Bangladeshi adolescents aged 10–20 years with an average age at menarche of 15.8 years. Interpopulation differences between pre- and postmenarcheal girls are assessed and age patterns are compared to standards of U.S. and British adolescents. Bangladeshi adolescents are shorter and lighter for their age and lighter for their height than are U.S. adolescents. The growth spurt in height and weight is delayed and spread out over time, and growth rates are lower throughout the spurt when compared to British and U.S. girls. As in developed countries, most girls attain menarche after peak height velocity, while weight gain per year is highest around the time of menarche. There is no significant relationship between age at menarche and height or weight at menarche.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38544/1/1310020307_ftp.pd