Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.

Fast-neutron and photon doses determined with proportional counters and ionization chambers

A /sup 60/Co teletherapy source has recently been coupled to an existing source of fast neutrons. These sources may be operated to provide precise and controlled mixtures of photons and neutrons. In this work we report the application of paired miniature proportional counters to n/..gamma.. dose separation. Graphite- and A150 plastic-walled proportional counters were employed. Results are compared to dose values deduced from a cnventional A150 plastic ionization chamber and a neutron insensitive GM counter

Application of A150-plastic equivalent gases in microdosimetric measurements

Neutron dosimetry measurements with ionization chambers, for the most part, employ tissue equivalent plastic-walled cavities (Shonka A150) filled with either air or a methane-base tissue-like gas. The atomic composition of TE-gas and A150 plastic are not matched and are quite dissimilar from muscle. Awschalom and Attix (1980) have partially resolved the problem by formulating a novel A150-plastic equivalent gas. This establishes a homogeneous wall-gas cavity dosimeter for neutron measurements and confines the necessary corrections to the applications of kerma ratios. In this report, we present measurements of applications of two A150-plastic equivalent gases in a low pressure spherical proportional counter. Gas gains and alpha-particle resolutions were determined. For these A150-mixtures as well as a methane-based TE-gas and an Ar-CO/sub 2/ mixture, we report measurements of event size distributions from exposure to a beam of 14.8 MeV neutrons

Signal reconstruction as an effective means of detecting targets in a DAB-based PBR

This paper aims to validate the method of target detection by correlating a surveillance (target) signal with a reconstructed reference signal in DAB-based Passive Bistatic Radar (PBR). Whereas most conventional PBRs condition the surveillance signal by suppressing Direct Signal Interference (DSI) and then correlate this with a similarly measured reference signal to reveal targets, the approach adopted at FHR is to correlate the surveillance signal with a perfectly reconstructed, error-free, copy to the transmitted signal

Anti W comparisons for A150 plastic-equivalent gases, TE gas, and air

As part of our continuing evaluation of A150 plastic equivalent gases for neutron dosimetry, we have measured ionization ratios which are related to anti W ratios between gases in the p(66)Be(49) neutron beam at Fermilab. Additionally we have extended our earlier measurements (DeLuca, et al., 1980) at the UW gas target /sup 3/H(d,n)/sup 4/He neutron source to include an uncollimated beam geometry with ion chambers close to the target. Observed differences from the earlier results can probably be explained on the basis of neutron spectra, which await further determination