Development and use of a two-dimensional interferometer to measure mass flow from a multi-shell Z-pinch gas puff.

For gas puff Z-pinches, the K-shell x-ray yield is maximized with the use of a multi-shell nozzle. Optimization of the yield, verification of hydrodynamic models of the nozzle flows, and plausible MHD code modeling of the implosions require data on the radial and axial (R,Z) distribution of mass in the nozzle's flow field. Interferometry is a well-established technique for acquiring such data. We describe the development and use of a two-dimensional interferometer with emphasis on the required data reduction methods. We also show that the instrument can derive the flow from each individual nozzle in a multi-shell system.

Practical aspects of radiation safety for using fluorine-18.

The use of positron-emitting nuclides is becoming routine in nuclear medicine departments today. Introducing these nuclides into the nuclear medicine department can be a smooth transition by instituting educational lectures, radiation safety protocols and patient education. The radiation safety concerns of the technical staff, physicians and ancillary personnel are important and must be addressed. Nuclear medicine departments can be optimistic about implementing PET imaging while staying well within ALARA guidelines. After reading this article, the technologist should be able to: (a) describe at least three ways to reduce the radiation dose to the technologist during the performance of PET imaging procedures with 18F; (b) discuss the relationships between gamma-ray energy, the amount of activity administered to a patient, exposure time and occupational dose; and (c) describe one strategy to minimize the radiation dose to the bladder in patients who have received 18F.

Hypomorphic mutations in the larval photokinesis A (lphA) gene have stage-specific effects on visual system function in Drosophila melanogaster.

Of the many genes that are expressed in the visual system of Drosophila melanogaster adults, some affect larval vision. However, with the exception of one X-linked mutation, no genes that have larval-specific effects on visual system structure or function have previously been reported. We describe the isolation and characterization of two mutant alleles that define the larval photokinesis A (lphA) gene, one allele of which is associated with a P-element insertion at cytogenetic locus 8E1-10. Larvae that express lphA mutations are, like normal animals, negatively photokinetic, but they are less responsive to white light than lphA + controls. Larvae that are heterozygous in trans for a mutant lphA allele and a deficiency that uncovers the lphA locus are blind, which indicates that the mutant allele is hypomorphic. lphA larvae respond normally to odorants and taste stimuli. Moreover, the lphA mutations do not affect adult flies' fast phototaxis or visually driven aspects of male sexual behavior, and electroretinograms recorded from the compound eyes of lphA/deficiency heterozygotes and lphA1/lphA2 females are normal. These observations suggest that the lphA gene affects a larval-specific aspect of visual system function.