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  • 1
    Electronic Resource
    Electronic Resource
    Spectroscopic and Potentiometric Investigation of a Diprotic Acid: An Experimental Approach to Understanding Alpha Functions (1999)
    Springer
    The chemical educator 4 (1999), S. 68-72 
    Details
    ISSN: 1430-4171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A laboratory experiment suitable for second- or higher-year chemistry students uses thymol blue, an organic dye, for investigating the fraction of each colored species present as a function of pH. Visible color changes in the vivid, highly absorbing dye permit students to “see” relative amounts of acid, base, and ampholyte species during the titration, while potentiometric measurement of pH and spectroscopic determination of concentrations permit quantitation of the species present. A standard Beer’s law calibration curve is constructed for known concentrations of the pure forms of each species at a pH where that species is present as nearly 100% of the total analytical concentration of the dye. Using the molar absorptivities of the three species computed from the calibration curves, simultaneous determination of concentration by species is performed on a set of solutions having constant total concentration of dye such that each solution represents one point in the range pH 0 to pH 13. A mathematical software application is used to solve the simultaneous equations and determine the fraction of each species present. Students then use a spreadsheet application to plot the fractions as functions of pH (the alpha functions). The significance of the isosbestic points in the spectra is also explored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00897990288a
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  • 2
    Electronic Resource
    Electronic Resource
    Book reviews (1990)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 8 (1990), S. 449-450 
    Details
    ISSN: 1573-1111
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01041201
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  • 3
    Electronic Resource
    Electronic Resource
    Cantaloupe line CZW-30 containing coat protein genes of cucumber mosaic virus, zucchini yellow mosaic virus, and watermelon mosaic virus-2 is resistant to these three viruses in the field (1997)
    Springer
    Molecular breeding 3 (1997), S. 279-290 
    Details
    ISSN: 1572-9788
    Keywords: coat protein-mediated protection ; Cucumis melo L. var. cantalupensis Naudin ; field evaluation ; increased field ; transgenic plants ; virus resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cantaloupe line CZW-30 containing coat protein gene constructs of cucumber mosaic cucumovirus (CMV), zucchini yellow mosaic potyvirus (ZYMV), and watermelon mosaic virus 2 potyvirus (WMV-2) was investigated in the field over two consecutive years for resistance to infections by CMV, ZYMV, and/or WMV-2. Resistance was evaluated under high disease pressure achieved by mechanical inoculations and/or natural challenge inoculations by indigenous aphid vectors. Across five different trials, homozygous plants were highly resistant in that they never developed systemic symptoms as did the nontransformed plants but showed few symptomatic leaves confined close to the vine tips. Hemizygous plants exhibited a significant delay (2–3 weeks) in the onset of disease compared to control plants but had systemic symptoms 9–10 weeks after transplanting to the field. Importantly, ELISA data revealed that transgenic plants reduced the incidence of mixed infections. Only 8% of the homozygous and 33% of the hemizygous plants were infected by two or three viruses while 99% of the nontransformed plants were mixed infected. This performance is of epidemiological significance. In addition, control plants were severely stunted (44% reduction in shoot length) and had poor fruit yield (62% loss) compared to transgenic plants, and most of their fruits (60%) were unmarketable. Remarkably, hemizygous plants yielded 7.4 times more marketable fruits than control plants, thus suggesting a potential commercial performance. This is the first report on extensive field trials designed to assess the resistance to mixed infection by CMV, ZYMV, and WMV-2, and to evaluate the yield of commercial quality cantaloupes that are genetically engineered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009640229952
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  • 4
    Electronic Resource
    Electronic Resource
    A comparison of strengthening mechanisms in rolled and axisymmetrically deformed Ti-20Y composites (1999)
    Springer
    Journal of materials science 34 (1999), S. 1447-1460 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Two Ti-20%Y metal-metal composites were deformation processed: one axisymmetrically and the other by rolling. The microstructures, preferred crystallographic orientations, and tensile strengths of each were measured periodically as the deformation progressed. The axisymmetrically deformed Ti matrix developed a [10 $$\bar 1$$ 0] fiber texture, and the rolled composite acquired a texture with the 〈0001〉 tilted 31° from the sheet normal toward the transverse direction with [10 $$\bar 1$$ 0] parallel to the rolling direction. The orientations of the {10 $$\bar 1$$ 0}〈11 $$\bar 2$$ 0〉 and (0002)〈11 $$\bar 2$$ 0〉 slip systems in Ti with these textures were used in conjunction with the maximum possible slip distances for dislocation travel in each specimen to demonstrate that the axisymmetrically deformed material should be stronger than the rolled material for composites of equal phase thickness and spacing. The strengths of the two composites measured in this study were compared at similar microstructural phase sizes and spacings, and the axisymmetrically deformed composite was indeed found to be somewhat stronger, although the difference in strengths was not large.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004542221169
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  • 5
    Electronic Resource
    Electronic Resource
    Organization of the ribosomal ribonucleic acid genes in various wild-type strains and wild-collected strains of Neurospora (1984)
    Springer
    Molecular genetics and genomics 196 (1984), S. 275-282 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The organization of the ribosomal DNA (rDNA) repcat unit in the standard wild-type strain of Neurospora crassa, 74-OR23-1A, and in 30 other wild-type strains and wild-collected strains of N. crassa, N. tetrasperma, N. sitophila, N. intermedia, and N. discreta isolated from nature, was investigated by restriction enzyme digestion of genomic DNA, and probing of the Southern-blotted DNA fragments with specific cloned pieces of the rDNA unit from 74-OR23-1A. The size of the rDNA unit in 74-OR23-1A was shown to be 9.20 kilobase pairs (kb) from blotting data, and the average for all strains was 9.11+0.21 kb; standard error=0.038; coefficient of variation (C.V.)=2.34%. These data indicate that the rDNA repeat unit size has been highly conserved among the Neurospora strains investigated. However, while all strains have a conserved HindIII site near the 5′ end of the 25 S rDNA coding sequence, a polymorphism in the number and/or position of HindIII sites in the nontranscribed spacer region was found between strains. The 74-OR23-1A strain has two HindIII sites in the spacer, while others have from 0 to at least 3. This restriction site polymorphism is strain-specific and not species-specific. It was confirmed for some strains by restriction analysis of clones containing most of the rDNA repeat unit. The current restriction map of the 74-OR23-1A rDNA repeat unit is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328060
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  • 6
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    Rapid compact jet quenching in the Galactic black hole candidate X-ray binary MAXI J1535−571 (2020)
    Oxford University Press
    Details
    Publication Date: 2020-09-01
    Description: We present results from six epochs of quasi-simultaneous radio, (sub-)millimetre, infrared, optical, and X-ray observations of the black hole X-ray binary MAXI J1535−571. These observations show that as the source transitioned through the hard–intermediate X-ray state towards the soft–intermediate X-ray state, the jet underwent dramatic and rapid changes. We observed the frequency of the jet spectral break, which corresponds to the most compact region in the jet where particle acceleration begins (higher frequencies indicate closer to the black hole), evolves from the infrared band into the radio band (decreasing by ≈3 orders of magnitude) in less than a day. During one observational epoch, we found evidence of the jet spectral break evolving in frequency through the radio band. Estimating the magnetic field and size of the particle acceleration region shows that the rapid fading of the high-energy jet emission was not consistent with radiative cooling; instead, the particle acceleration region seems to be moving away from the black hole on approximately dynamical time-scales. This result suggests that the compact jet quenching is not caused by local changes to the particle acceleration, rather we are observing the acceleration region of the jet travelling away from the black hole with the jet flow. Spectral analysis of the X-ray emission shows a gradual softening in the few days before the dramatic jet changes, followed by a more rapid softening ∼1–2 d after the onset of the jet quenching.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press on behalf of The Royal Astronomical Society.
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  • 7
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    The reproducible radio outbursts of SS Cygni (2016)
    Oxford University Press
    Details
    Publication Date: 2016-06-24
    Description: We present the results of our intensive radio observing campaign of the dwarf nova SS Cyg during its 2010 April outburst. We argue that the observed radio emission was produced by synchrotron emission from a transient radio jet. Comparing the radio light curves from previous and subsequent outbursts of this system (including high-resolution observations from outbursts in 2011 and 2012) shows that the typical long and short outbursts of this system exhibit reproducible radio outbursts that do not vary significantly between outbursts, which is consistent with the similarity of the observed optical, ultraviolet and X-ray light curves. Contemporaneous optical and X-ray observations show that the radio emission appears to have been triggered at the same time as the initial X-ray flare, which occurs as disc material first reaches the boundary layer. This raises the possibility that the boundary region may be involved in jet production in accreting white dwarf systems. Our high spatial resolution monitoring shows that the compact jet remained active throughout the outburst with no radio quenching.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 8
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    Radio monitoring of the hard state jets in the 2011 outburst of MAXI J1836-194 (2015)
    Oxford University Press
    Details
    Publication Date: 2015-04-30
    Description: MAXI J1836–194 is a Galactic black hole candidate X-ray binary that was discovered in 2011 when it went into outburst. In this paper, we present the full radio monitoring of this system during its ‘failed’ outburst, in which the source did not complete a full set of state changes, only transitioning as far as the hard intermediate state. Observations with the Karl G. Jansky Very Large Array (VLA) and Australia Telescope Compact Array (ATCA) show that the jet properties changed significantly during the outburst. The VLA observations detected linearly polarized emission at a level of ~1 per cent early in the outburst, increasing to ~3 per cent as the outburst peaked. High-resolution images with the Very Long Baseline Array (VLBA) show an ~15 mas jet along the position angle –21 ± 2°, in agreement with the electric vector position angle found from our polarization results (–21 ± 4°), implying that the magnetic field is perpendicular to the jet. Astrometric observations suggest that the system required an asymmetric natal kick to explain its observed space velocity. Comparing quasi-simultaneous X-ray monitoring with the 5 GHz VLA observations from the 2011 outburst shows an unusually steep hard-state radio/X-ray correlation of $L_{\rm R} \propto L_{\rm X}^{1.8\pm 0.2}$ , where L R and L X denote the radio and X-ray luminosities, respectively. With ATCA and Swift monitoring of the source during a period of re-brightening in 2012, we show that the system lay on the same steep correlation. Due to the low inclination of this system, we then investigate the possibility that the observed correlation may have been steepened by variable Doppler boosting.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 9
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    Using synthetic seismicity to evaluate seismic hazard in the Wellington region, New Zealand (2011)
    Oxford University Press
    Details
    Publication Date: 2011-08-27
    Description: SUMMARY A computer synthetic seismicity program for the Wellington region has been implemented and used to infer the effect of the 1848 Awatere and 1855 Wairarapa mega-earthquakes on the timing of the next characteristic (magnitude 7.35 or more) earthquake on the Wellington–Hutt Valley section of the Wellington Fault. We find that, on average over several hundred cases, a Wellington Fault event is delayed by 259 years. The synthetic catalogue of 500 000 events, magnitude 5.5 or more, also gives the average recurrence time of characteristic Wellington Fault events (960 yr) and their Coefficient of Variation (0.40). There is also a strong retarding effect on moderate magnitude Wellington Fault events, magnitude 6.5–7.3. Sensitivity tests indicate that these results are robust. The synthetic model contains 58 known major faults and 3000 randomly placed small faults to reproduce the rate and spatial distribution of background seismicity observed recently. From the synthetic catalogue it is possible to determine the average recurrence rate for all major faults. Also, there is strong evidence of the short-term (10 yr) temporal clustering of large events throughout the region, a factor that contributes to a highly variable moment release rate over time spans of a few hundred years.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 10
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    The accretion-ejection coupling in the black hole candidate X-ray binary MAXI J1836-194 (2014)
    Oxford University Press
    Details
    Publication Date: 2014-03-09
    Description: We present the results of our quasi-simultaneous radio, submm, infrared, optical and X-ray study of the Galactic black hole candidate X-ray binary MAXI J1836–194 during its 2011 outburst. We consider the full multiwavelength spectral evolution of the outburst, investigating whether the evolution of the jet spectral break (the transition between optically thick and optically thin synchrotron emission) is caused by any specific properties of the accretion flow. Our observations show that the break does not scale with the X-ray luminosity or with the inner radius of the accretion disc, and is instead likely to be set by much more complex processes. We find that the radius of the acceleration zone at the base of the jet decreases from ~10 6 gravitational radii during the hard intermediate state to ~10 3 gravitational radii as the outburst fades (assuming a black hole mass of 8 M ), demonstrating that the electrons are accelerated on much larger scales than the radius of the inner accretion disc and that the jet properties change significantly during outburst. From our broad-band modelling and high-resolution optical spectra, we argue that early in the outburst, the high-energy synchrotron cooling break was located in the optical band, between 3.2 10 14 and 4.5 10 14  Hz. We calculate that the jet has a total radiative power of 3.1 10 36  erg s –1 , which is ~6 per cent of the bolometric radiative luminosity at this time. We discuss how this cooling break may evolve during the outburst, and how that evolution dictates the total jet radiative power. Assuming the source is a stellar mass black hole with canonical state transitions, from the measured flux and peak temperature of the disc component we constrain the source distance to be 4–10 kpc.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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