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  • 1
    Electronic Resource
    Electronic Resource
    Mixed deposits of complex magmatic and phreatomagmatic volcanism: an example from Crater Hill, Auckland, New Zealand (1996)
    Springer
    Bulletin of volcanology 58 (1996), S. 59-66 
    Details
    ISSN: 1432-0819
    Keywords: Key words Explosive volcanism ; Magmatic ; Phreatomagmatic ; Crater Hill ; Basalt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  A series of alternating phreatomagmatic ("wet") and magmatic ("dry") basaltic pyroclastic deposits forming the Crater Hill tuff ring in New Zealand contains one unit (M1) which can only be interpreted as the products of mixing of ejecta from simultaneous wet and dry explosions at different portions of a multiple vent system. The principal characteristics of M1 are (a) rapid lateral changes in the thicknesses of, and proportions in juvenile components in individual beds, and (b) wide ranges of juvenile clast densities in every sample. M1 appears to have been associated with an elongate source of highly variable and fluctuating magma : water ratios and magma discharge rates. This contrasts with the only other documented mixed (wet and dry) basaltic pyroclastic deposits where mixing from two point sources of quite different but stable character has been inferred.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004450050126
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  • 2
    Electronic Resource
    Electronic Resource
    The geochemistry of potassic lavas from Vulsini, central Italy and implications for mantle enrichment processes beneath the Roman region (1985)
    Springer
    Contributions to mineralogy and petrology 90 (1985), S. 244-257 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Major and trace element and 143Nd/144Nd (0.51209–0.51216) and 87Sr/86Sr (0.70879–0.71105) isotope analyses are presented on a representative group of lavas from the Vulsini district of the Roman magmatic province. Three distinct series are identified; the high-K and low-K series are similar to those described from other Italian volcanoes, while the third is represented by a group of relative ly undifferentiated leucite basanites which are thought to be near-primary mantle melts. Major and trace element variations within the high-K series are consistent with fractional crystallisation from a parental magma similar to the most magnesian leucitites. Crustal contamination resulted in an increase in 87Sr/86Sr with increasing fractionation, but it was superimposed on magmas which had already inherited a range of incompatible element and isotope ratios from enrichment processes in the sub-continental mantle. These are reviewed using the available results from Vulsini, Roccamonfina and Ernici. Transition element abundances and Ta/Yb ratios indicate that the pre-enrichment mantle was similar to that of E-type MORB, and that these elements were not mobilised by the enrichment process. Mixing calculations suggest that three components were involved in the enrichment process; mantle comparable with the source of MORB, and two other components rich in trace elements. One, the low-K component, had high Sr/Nd, Th/Ta and Ba/Nb and no europium anomaly while the second had lower Sr/Nd, a negative europium anomaly and very high Th/Ta. It was also characterised by low Nb/Ba and high Rb/Ba ratios, similar to those reported from phlogopite-rich peridotite xenoliths. The trace element enrichment processes are therefore thought to have occurred in the mantle wedge above a subduction zone with the trace element characteristics of the high-K end-member reflecting the subduction of sediments and the stabilisation of mantle phlogopite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378265
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  • 3
    Electronic Resource
    Electronic Resource
    Genetic correlation and response to selection in simulated populations (1970)
    Springer
    Theoretical and applied genetics 40 (1970), S. 157-162 
    Details
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary One of two quantitative traits was selected and correlated response in the other trait was measured in each of 30 generations for models of additive genes and of complete dominance. Each trait was controlled by 48 loci with equal effects, segregating independently from frequencies of 0.5 in the initial generation. Intensity of selection regulated the number of offspring from randomly mating 24 males and 24 females each generation. Three each of genetic correlations between traits, intensities of selection, and amounts of environmental variation were simulated. In the additive model correlated responses of the unselected trait to selection of the primary trait agreed closely with responses expected from theoretical considerations. In the model of complete dominance, responses of genotypic means of the unselected trait to selection of the primary trait in opposite directions were quite symmetrical for the first few generations but became distinctly asymmetrical in later generations. With little selection, response was fairly linear but became distinctly curvilinear as intensity of selection increased and environmental variance decreased. Between 15th and 30th generations some gains in the correlated trait to the 15th generation were lost.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00282696
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  • 4
    Electronic Resource
    Electronic Resource
    Genetic correlation and response to selection in simulated populations (1970)
    Springer
    Theoretical and applied genetics 40 (1970), S. 106-110 
    Details
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Effects of truncation selection of a primary trait upon genetic correlation between the primary trait and an unselected secondary trait were observed during 30 generations. Populations were 24 male and 24 female parents per generation randomly mated with replacement, the number of offspring set by intensity of selection. Each trait was controlled by genes with equal effects and complete dominance segregating independently from starting frequencies of 0.5 at each of 48 loci. Three levels each of genetic correlation, selection, and environmental variation were simulated. Genetic correlation decreased faster under more intense selection by lower than by upper truncation but behaved similarly in both by remaining near initial level when as many as one-half of the offspring were saved for parents. Truncation selection decreased genetic correlation in the offspring selected to be parents whether selection was by upper or lower truncation. Estimates of genetic correlation from covariances between phenotypes of parent and offspring were erratic for both directions of selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00997001
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic correlation and response to selection in simulated populations (1969)
    Springer
    Theoretical and applied genetics 39 (1969), S. 365-370 
    Details
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Effects of truncation selection of a primary trait upon genetic correlation with a secondary trait were examined over 30 generations in genetic populations simulated by computer. Populations were 24 males and 24 females mated randomly with replacement; number of offspring was determined by intensity of selection. Each trait was controlled by 48 loci segregating independently, effects were equal at every locus, and gene frequency was arbitrarily set at 0.5 at each locus in the initial generation. All combinations of three genetic correlations, three intensities of selection, and three environmental variances were simulated. Gene action was additive. Genetic correlation was set by number of loci which affected both traits and was measured each generation as the product-moment correlation of genotypic values and estimated by two methods of combining phenotypic covariances between parent and offspring. Genetic correlations in each offspring generation remained consistently near initial correlations for all environmental variances when fraction of offspring saved as parents was as large as one-half. When the fraction of offspring saved was as small as one-fifth, genetic correlations decreased but most rapidly with heritability high and after the 15th generation of selection. Truncation selection caused genetic correlation to decrease in those offspring selected to become parents of the next generation. Amount of reduction depended on heritability of the selected trait rather than on degree of truncation selection. Estimates of genetic correlation from phenotypic covariances between parent and offspring fluctuated markedly from real correlations in the small populations simulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290875
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  • 6
    Electronic Resource
    Electronic Resource
    An iterative method for determining background intensities used in XRF calibration lines for flux-fusion silicate rock analysis (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 7 (1978), S. 38-43 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In major element rock analysis using XRF and fused samples and standards, the construction of standard calibration lines is facilitated by the accurate knowledge of the background intensities for the elements analyed. As an alternative to measuring the background ‘off peak’ or on blanks, an iterative technique is proposed. This technique is based on repeatedly incrementing the background value until the best calibration line has been found. The quality of the calibration line is evaluated in terms of the average relative and average absolute errors. Comparative data, presented for calibration lines constructed from (1) backgrounds measured from blanks and (2) backgrounds determined by iterationm, show that the iterative technique produces superior calibrations. The analytical techniques have been tested by analysing international rock standards as unknown samples.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300070112
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  • 7
    Electronic Resource
    Electronic Resource
    Single pass major element x-ray fluorescence analysis of silicate rock samples using a Philips 1212 spectrometer (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 11 (1982), S. 100-108 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A ‘single pass’ method of analysing silicate rocks for their major element composition has been developed using a Philips 1212 x-ray fluorescence spectrometer. Samples need only be submitted once to the spectrometer and all ten major elements (SiO2, TiO2, Al2O3, Fe2O3T, MnO, MgO, CaO, Na2O, K2O and P2O5) are determined using a Cr x-ray tube and three analysing crystals, i.e. TIAP, PET and LiF220. The method has been evaluated in terms of the quality of the calibration lines for each element, the precision of replicated analyses and by the analysis of rock standards as unknown samples. The single pass method is rapid, facilitates on-line data reduction and is capable of producing high quality analytical data.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300110303
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  • 8
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    Comparisons between different techniques for measuring mass segregation (2015)
    Oxford University Press
    Details
    Publication Date: 2015-04-10
    Description: We examine the performance of four different methods which are used to measure mass segregation in star-forming regions: the radial variation of the mass function $\mathcal {M}_{\rm MF}$ ; the minimum spanning tree-based MSR method; the local surface density LDR method; and the GSR technique, which isolates groups of stars and determines whether the most massive star in each group is more centrally concentrated than the average star. All four methods have been proposed in the literature as techniques for quantifying mass segregation, yet they routinely produce contradictory results as they do not all measure the same thing. We apply each method to synthetic star-forming regions to determine when and why they have shortcomings. When a star-forming region is smooth and centrally concentrated, all four methods correctly identify mass segregation when it is present. However, if the region is spatially substructured, the GSR method fails because it arbitrarily defines groups in the hierarchical distribution, and usually discards positional information for many of the most massive stars in the region. We also show that the MSR and LDR methods can sometimes produce apparently contradictory results, because they use different definitions of mass segregation. We conclude that only MSR measures mass segregation in the classical sense (without the need for defining the centre of the region), although LDR does place limits on the amount of previous dynamical evolution in a star-forming region.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 9
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    Understanding and Predicting Permanent Magnet Performance by Electrical Analog Methods (1958)
    American Institute of Physics
    Details
    Publication Date: 1958-03-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics
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  • 10
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    Permanent Magnet Leakage Permeance Evaluation Based on Polar Radiation Analogy (1960)
    American Institute of Physics
    Details
    Publication Date: 1960-05-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics
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