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130 results on '"Price, H. J."'

14. Learning from Earthquakes. The Mw 6.3 Abruzzo, Italy, Earthquake of April 6, 2009

Author

Bazzurro P., Alexander D., Clemente P., Comerio M., De Sortis A., Filippou F., Goretti A., Jorjani M., Mollaioli F., Mosalam K., Price H. J., Court C. P., Schotanus M., Stewart J., Bazzurro, P., Alexander, D., Clemente, P., Comerio, M., De Sortis, A., Filippou, F., Goretti, A., Jorjani, M., Mollaioli, F., Mosalam, K., Price, H. J., Court, C. P., Schotanus, M., and Stewart, J.

Published
2009

37. Sorghum laxiflorumandS. macrospermum,the Australian native species most closely related to the cultivatedS. bicolorbased on ITS1 andndhF sequence analysis of 25Sorghumspecies.

Author

Dillon, S. L., Lawrence, P. K., Henry, R. J., Ross, L., Price, H. J., and Johnston, J. S.

Subjects
SPECIES, GENETICS, SORGHUM (Genus), GRASSES, FORAGE plants, GENES
Abstract

Australian species make up seventeen of the world’s twenty-five recognised species ofSorghum, with the genus separated into five sections:Eu-sorghum, Chaetosorghum, Heterosorghum, Para-sorghumandStiposorghum. Whereas the genetic relationships within sectionEu-sorghumare well known, little is known about the genetic relationships and crossabilities outside the primary genepool. We made a detailed investigation of phylogenetic relationships withinSorghumto identify wild species most closely related to cultivated sorghum (with outgroupsZea maysandSaccharum officinarum). The ribosomal ITS1 gene of ten species and the chloroplastndhF gene from nineteen species were sequenced. Independent and combined analyses of the ITS1 andndhF data sets were undertaken. TheEu-sorghumspecies were resolved into a strongly supported lineage by all three analyses, and included the Australian nativesS. laxiflorumandS. macrospermumin the ITS1 and combined analyses. All remaining sorghum species were resolved into a second well-supported lineage in the combined analyses, although some internal relationships within this second lineage remain unresolved. We identifiedS. laxiflorumandS. macrospermumas the Australian species most closely related to cultivated sorghum. Our data support a reduction in the number of subgeneric sections from five to three:Eu-sorghum(unchanged); a combinedChaetosorghum/Heterosorghumto reflect the very close relationship between these two species; and a combinedPara-sorghum/Stiposorghumsection, thereby removing the unclear taxonomic and genetic boundaries between these species. [ABSTRACT FROM AUTHOR]

Published
2004
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42. Dispersed repetitive DNA has spread to new genomes since polyploid formation in cotton.

Author

Zhao, X P, Si, Y, Hanson, R E, Crane, C F, Price, H J, Stelly, D M, Wendel, J F, and Paterson, A H

Abstract

Polyploid formation has played a major role in the evolution of many plant and animal genomes; however, surprisingly little is known regarding the subsequent evolution of DNA sequences that become newly united in a common nucleus. Of particular interest is the repetitive DNA fraction, which accounts for most nuclear DNA in higher plants and animals and which can be remarkably different, even in closely related taxa. In one recently formed polyploid, cotton (Gossypium barbadense L.; AD genome), 83 non-cross-hybridizing DNA clones contain dispersed repeats that are estimated to comprise about 24% of the nuclear DNA. Among these, 64 (77%) are largely restricted to diploid taxa containing the larger A genome and collectively account for about half of the difference in DNA content between Old World (A) and New World (D) diploid ancestors of cultivated AD tetraploid cotton. In tetraploid cotton, FISH analysis showed that some A-genome dispersed repeats appear to have spread to D-genome chromosomes. Such spread may also account for the finding that one, and only one, D-genome diploid cotton, Gossypium gossypioides, contains moderate levels of (otherwise) A-genome-specific repeats in addition to normal levels of D-genome repeats. The discovery of A-genome repeats in G. gossypioides adds genome-wide support to a suggestion previously based on evidence from only a single genetic locus that this species may be either the closest living descendant of the New World cotton ancestor, or an adulterated relic of polyploid formation. Spread of dispersed repeats in the early stages of polyploid formation may provide a tag to identify diploid progenitors of a polyploid. Although most repetitive clones do not correspond to known DNA sequences, 4 correspond to known transposons, most contain internal subrepeats, and at least 12 (including 2 of the possible transposons) hybridize to mRNAs expressed at readily discernible levels in cotton seedlings, implicating transposition as one possible mechanism of spread. Integration of molecular, phylogenetic, and cytogenetic analysis of dispersed repetitive DNA may shed new light on evolution of other polyploid genomes, as well as providing valuable landmarks for many aspects of genome analysis.

Published
1998

43. Two-Port Representation of a Linear Transmission Line in the Time Domain.

Author

MISSION RESEARCH CORP ALBUQUERQUE NM, Price,H J, St John,R H, Merewether,D E, MISSION RESEARCH CORP ALBUQUERQUE NM, Price,H J, St John,R H, and Merewether,D E

Abstract

This report discusses the adaptation of a linear section transmission line to a time-domain code. The linear section is described by frequency-domain parameters appropriately transformed into the time domain. On both ends of the linear section, the time-domain code employs difference equations to describe regions which may exhibit a nonlinear response. The interface between the linear and potentially nonlinear sections of cable produce boundary conditions joining the variant mathematical descriptions of the regions. This document reports on the formulation (in the time domain) of a two-part representation for a linear transmission line, and the joining of this result to a nonlinear, time-domain, transmission-line code. In general, the nonlinearities can occur in two regions: The first, or primary breakdown region, close to the burst, results from the high intensity fields associated with the nuclear device. The second, or secondary breakdown region, can occur at a discontinuity in the line far from the area of detonation. These are caused by signals propagated by the line and reflected at the discontinuity. These two regions are separated by a linear section of cable. Of course, this central line section is quite compatible with the nonlinear codes; that is, the difference equations representing the transmission-line equations are compatible with linear, as well as nonlinear, line behavior.

Published
1980

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