Trypanosoma cruzi, the causative agent of Chagas' disease, is a member of the Kinetoplastid family. Advances in the understanding of gene expression by Kinetoplastids has aided the construction of ...vectors allowing the expression of foreign genes by these organisms. After electroporation of circular DNA into kinetoplastids and selection for stable expression, the DNA may be maintained extrachromosomally as an episome or may integrate into the parasite genome. In contrast, after transfection of linear DNA constructs and selection for stable expression, the linear element integrates at homologous sites, causing gene replacement. This paper describes the structure and expression of the resulting episomal DNA and gene replacements in transfected T. cruzi under normal selective conditions and after drug amplification.
An equal group delay waveguide lens Ajioka, J.; Ramsey, V.
IEEE transactions on antennas and propagation,
07/1978, Letnik:
26, Številka:
4
Journal Article
Recenzirano
Analytical and experimental results are presented on a circularly polarized waveguide lens that has much greater bandwidth than conventional waveguide lenses. This is achieved by designing the lens ...to have equal group delay for all rays from the focal point of the lens to the aperture plane. Haft-wave-plate phase shifters in each waveguide element are then oriented to produce a planar phase front. This results in a lens whose aperture phase distribution remains essentially constant over a much wider frequency range than in conventional waveguide lenses. A comparison with a minimum thickness conventional lens and with a phase compensated (Coulbourn) lens is made. A 46-in X band lens was built and tested over a frequency range from 7-9 GHz to confirm the bandwidth performance.
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