James M. Johnson

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Genotyping-by-sequencing (GBS) approaches provide low-cost, high-density genotype information. However, GBS has unique technical considerations, including a substantial amount of missing data and a nonuniform distribution of sequence reads. The goal of this study was to characterize technical variation using this method and to develop methods to optimize(More)
Atmospheric water vapor can also be measured using GPS [Dixon and Kornreich Wolf, 1m; Bevis et aI., 1992]. PWV ranges from O. 60 mm. We show that GPS can estimate PWV with mm accuracy every 30 minutes. PWV measurements of this accuracy and frequency are useful for meteorology and hold promise to aid in the estimation of vertical watel" vapor profiles [Kuo(More)
Genomes at the species level are dynamic, with genes present in every individual (core) and genes in a subset of individuals (dispensable) that collectively constitute the pan-genome. Using transcriptome sequencing of seedling RNA from 503 maize (Zea mays) inbred lines to characterize the maize pan-genome, we identified 8681 representative transcript(More)
QTL were identified for root architectural traits in maize. Root architectural traits, including the number, length, orientation, and branching of the principal root classes, influence plant function by determining the spatial and temporal domains of soil exploration. To characterize phenotypic patterns and their genetic control, three recombinant inbred(More)
Aminoacyl-tRNA synthetases are multidomain enzymes that catalyze covalent attachment of amino acids to their cognate tRNA. Cross-talk between functional domains is a prerequisite for this process. In this study, we investigate the molecular mechanism of site-to-site communication in Escherichia coli prolyl-tRNA synthetase (Ec ProRS). Earlier studies have(More)
This commentary examines Genesee County (Flint) Michigan to explore whether a well-structured safety net system is able to provide low-income uninsured people adequate access to care at a reasonable cost. Genessee County is one of the more economically challenged communities in the country. This commentary explores the cost and adequacy of safety net care(More)
An ultralow-standby-power technology has been developed in both 0.18m and 0.13m lithography nodes for embedded and standalone SRAM applications. The ultralow-leakage sixtransistor (6T) SRAM cell sizes are 4.81 m and 2.34 m, corresponding respectively to the 0.18m and 0.13m design dimensions. The measured array standby leakage is equal to an average cell(More)
PURPOSE In the management of head and neck cancer, it is often necessary to junction photon and electron fields. When patients are treated supine, electron cones or applicators may have to be positioned at source to surface distance (SSD) greater than the standard 100 cm because of the patient's shoulders. We have studied the dosimetric effects of abutting(More)
PURPOSE The spine can be treated with an electron beam when its maximum posterior depth is within the therapeutic range of electrons. Electron fields treated at extended source-to-surface distances (SSDs), however, have larger penumbras and narrower therapeutic isodose widths relative to those at the standard SSD of 100 cm. We investigated the use of(More)