84 research outputs found
Reply to comment by H. Hasegawa on "Evolution of Kelvin-Helmholtz activity on the dusk flank magnetopause"
No full textWe demonstrate, on experimental grounds, that the justifications for the comment by Hasegawa [2009], hereinafter
H09, on work done by Foullon et al. [2008], hereinafter F08, are not well founded
Genetic variation of the ribosomal DNA intergenic spacer of maize
No full textFour maize (Zea mays L.) populations selected for grain yield BS10, BS11, RBS10, and RSSSC, were assayed for molecular variation in the ribosomal DNA (rDNA) intergenic spacer (IGS) at initial and advanced cycles of selection. RSSSC and RBS10 underwent reciprocal recurrent selection with an inbred tester in a high yield environment, whereas BS10 and BS11 were subjected to full-sib reciprocal recurrent selection. Maize rDNA, is highly repetitive and shows IGS length variation within and among individuals. Five different ribosomal spacer length variants (rslvs) and a polymorphic SstI restriction site were detected in the four populations. The 5 rslvs and the polymorphic restriction fragment were observed in twenty different combinations, or hybridization fragment patterns (HP). RSSSC, RBS10, and BS11 showed significant changes in the overall rslv and HP frequencies between cycle 0 and the advanced cycle of selection, whereas BS10 did not. In general, two specific HPs were more frequent in the majority of the advanced cycles of the four populations. The frequency changes between initial and advanced cycles were more dramatic for HPs than rslvs. These results are consistent with earlier findings and further support the hypothesis that certain rDNA HPs may be responding to selection for grain yield and may be associated with a selective advantage in US Corn Belt environments.Most maize rDNA intergenic spacer studies have concentrated on US Corn Belt germplasm. We examined the genetic variation of the maize rDNA IGS region in 70 maize lines/populations from geographically diverse maize growing regions. Despite the very broad scope of the survey, no new rslvs were discovered although many new HPs were observed. Notably, inbred lines from the Corn Belt (CB) exhibited a significantly different frequency distribution of HPs in comparison to non-Corn Belt (NCB) lines. The most frequent HP among the CB and among the NCB inbred lines differed only in the presence/absence of the polymorphic SstI site in the external transcribed spacer region of the IGS. This suggests that sequence variation in the non-repetitive spacer segment might be associated with lines derived from different ecogeographic areas. We further conducted a comparative sequence analysis of the non-repetitive spacer segment from ribosomal transcription repeats within individuals, and among lines that differ for ribosomal HP. A sequence similarity of 92% to 99%, was found among the IGS repeats. Eighty three variable nucleotide positions constituted the variation along the 1.3 kb of spacer examined. Some segments of the sequence were more variable then others. Sequence variation was observed between repeats within an individual plant and among repeats from different lines. DNA sequence variation among repeats within individuals was of the same magnitude as the variation among repeats from different lines. The ribosomal clone that deviated the most from the consensus sequence of all studied repeats corresponds to the 3.4 kb rslv. Therefore, different rslvs may serve as markers of nucleotide variation in the ribosomal ETS.Made available in DSpace on 2011-05-07T12:02:14Z (GMT). No. of bitstreams: 2
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Previous issue date: 1995Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:35:48Z
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The Legal Status of United States Corporations and Individuals in Taiwan If United States--Republic of China Dipolmatic Relations Were Severed
No full textThe author reviews the treaty rights afforded U.S. corporations and individuals operating in Taiwan under present agreements and compares them with rights afforded non-treaty countries doing business in Taiwan. The author\u27s extensive examination reveals that, while present treaties appear to formally secure diplomatic relations, a severance thereof will not cause a great disruption of trade and investment between the U.S. and the Republic of China
The Legal Status of United States Corporations and Individuals in Taiwan If United States--Republic of China Dipolmatic Relations Were Severed
No full textThe author reviews the treaty rights afforded U.S. corporations and individuals operating in Taiwan under present agreements and compares them with rights afforded non-treaty countries doing business in Taiwan. The author\u27s extensive examination reveals that, while present treaties appear to formally secure diplomatic relations, a severance thereof will not cause a great disruption of trade and investment between the U.S. and the Republic of China
Quantitative trait loci mapping for grain yield and other traits of agronomic importance in maize
No full textSeveral marker loci were associated with more than one trait. Thus genes controlling these traits may map to the same chromosomal regions or have pleiotropic effects. Although a number of marker loci were associated with genotype by environment interactions (GXE) for grain yield among individual environments each year, the associations detected for combined environments within a year were stable between 1991 and 1992.Made available in DSpace on 2011-05-07T13:46:08Z (GMT). No. of bitstreams: 2
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Previous issue date: 1993Restriction fragment length polymorphisms (RFLPs) were used as molecular markers to identify chromosomal regions associated with quantitative traits in maize (Zea mays L.). Four Lancaster type inbreds were used to produce 66 F\sb7 recombinant inbred lines (RIs). One hundred-one RFLP loci were polymorphic among two or more of the parental inbreds and used to determine marker genotypes of the 66 RIs. Seventy-two of these markers that were polymorphic among the RIs were used to make associations with QTL. Phenotypic data were obtained from the evaluation of the line per se performance in replicated trials in 1992, and from testcross performance of the 66 RIs and four parents crossed to three diverse inbred testers. The testcross progeny were evaluated in replicated trials in two environments in 1991 and three environments in 1992.Association of the line per se data sets with molecular marker data revealed marker-trait associations for plant height, ear height, days to anthesis, and days to silk emergence. In most instances, marker loci having significant associations for plant height were also associated with ear height. A number of marker loci influencing plant height were identified in the same genomic regions as major qualitative mutants that affect plant stature.Association of yield trial data with molecular marker genotypes of the 66 RIs identified marker loci significantly associated with grain yield, grain moisture, stalk lodging, and root lodging. Some marker loci showed significant associations for grain yield with one or two testers, while others showed significant associations for grain yield with all three testers. Clusters of three or more RFLP loci significantly associated with grain yield on chromosomes 2S and 7L suggest the presence of major grain yield QTL at these locations.Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:58:56Z
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Genetic variation of the ribosomal DNA intergenic spacer of maize
No full textFour maize (Zea mays L.) populations selected for grain yield BS10, BS11, RBS10, and RSSSC, were assayed for molecular variation in the ribosomal DNA (rDNA) intergenic spacer (IGS) at initial and advanced cycles of selection. RSSSC and RBS10 underwent reciprocal recurrent selection with an inbred tester in a high yield environment, whereas BS10 and BS11 were subjected to full-sib reciprocal recurrent selection. Maize rDNA, is highly repetitive and shows IGS length variation within and among individuals. Five different ribosomal spacer length variants (rslvs) and a polymorphic SstI restriction site were detected in the four populations. The 5 rslvs and the polymorphic restriction fragment were observed in twenty different combinations, or hybridization fragment patterns (HP). RSSSC, RBS10, and BS11 showed significant changes in the overall rslv and HP frequencies between cycle 0 and the advanced cycle of selection, whereas BS10 did not. In general, two specific HPs were more frequent in the majority of the advanced cycles of the four populations. The frequency changes between initial and advanced cycles were more dramatic for HPs than rslvs. These results are consistent with earlier findings and further support the hypothesis that certain rDNA HPs may be responding to selection for grain yield and may be associated with a selective advantage in US Corn Belt environments.Most maize rDNA intergenic spacer studies have concentrated on US Corn Belt germplasm. We examined the genetic variation of the maize rDNA IGS region in 70 maize lines/populations from geographically diverse maize growing regions. Despite the very broad scope of the survey, no new rslvs were discovered although many new HPs were observed. Notably, inbred lines from the Corn Belt (CB) exhibited a significantly different frequency distribution of HPs in comparison to non-Corn Belt (NCB) lines. The most frequent HP among the CB and among the NCB inbred lines differed only in the presence/absence of the polymorphic SstI site in the external transcribed spacer region of the IGS. This suggests that sequence variation in the non-repetitive spacer segment might be associated with lines derived from different ecogeographic areas. We further conducted a comparative sequence analysis of the non-repetitive spacer segment from ribosomal transcription repeats within individuals, and among lines that differ for ribosomal HP. A sequence similarity of 92% to 99%, was found among the IGS repeats. Eighty three variable nucleotide positions constituted the variation along the 1.3 kb of spacer examined. Some segments of the sequence were more variable then others. Sequence variation was observed between repeats within an individual plant and among repeats from different lines. DNA sequence variation among repeats within individuals was of the same magnitude as the variation among repeats from different lines. The ribosomal clone that deviated the most from the consensus sequence of all studied repeats corresponds to the 3.4 kb rslv. Therefore, different rslvs may serve as markers of nucleotide variation in the ribosomal ETS.U of I OnlyETDs are only available to UIUC Users without author permissio
Evolution of Kelvin-Helmholtz activity on the dusk flank magnetopause
No full textOur purpose is to characterize the evolution of the magnetopause Kelvin-Helmholtz
(KH) wave activity with changes in thickness of the adjacent boundary layer,
geomagnetic latitude and interplanetary magnetic field (IMF) orientation. As the IMF
turns northward, wave activity may be generated at the dayside before propagating
down the tail, where the boundary layer is expected to support longer wavelengths. We
use two-point observations on the dusk magnetopause at low latitudes, from Geotail on
the dayside and Cluster tailward of the dusk terminator. We quantify the wavelength,
power, wavefront steepness and propagation direction at Cluster. An estimate of the
thickness of the low-latitude boundary layer (LLBL) is obtained by correlating normal
distances to the magnetopause, derived from two empirical solar-wind-driven models,
with a systematic relationship (the "transition parameter") found between the electron
number density and temperature; the correlation factor is used to infer the temporal
evolution of the thickness of the locally sampled layer. We find that wavelengths are
controlled by the IMF clock angle, as expected when generated by the KH mechanism
at the dayside, although amplitudes, wavefront steepness and propagation directions are
more closely correlated with the layer thickness. A survey of parameter space provides
evidence of the contribution of the KH mechanism to the widening of the electron LLBL
Automated calibration of a flight particle spectrometer
No full textA system for calibrating both electron and ion imaging particle spectrometers was devised to calibrate flight instruments in a large vacuum facility in the Space Science Laboratory at the Marshall Space Flight Center. An IBM-compatible computer was used to control, via an IEEE 488 buss protocol, a two-axis gimbled table, constructed to fit inside the tank. Test settings of various diagnostic voltages were also acquired via the buss. These spectrometers constructed by the author at UCSD were calibrated in an automatic procedure programmed on the small computer. Data was up-loaded to the SSL VAX where a program was developed to plot the results
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