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  • 1
    Electronic Resource
    Electronic Resource
    Microwave cavity spectrometer for process monitoring of ethylene oxide sterilization (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 103-108 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article reports a novel and simple cavity spectrometer for process monitoring of ethylene oxide sterilization, in which the source frequency, cavity resonant frequency, and gas absorption center frequency are asynchronous with respect to each other, thus, enabling sophisticated signal enhancement techniques to be employed without the need to engage the Stark effect. The operation of the device is such that the source frequency sweeps across a given range (F1 to F2) which contains one of the absorption peaks of the analyte gas (gases) of interest while the cavity resonant frequency Fr is oscillated within the profile of the absorption peak. Signal enhancement is achieved by adding a relatively small magnitude/high-frequency "dither'' signal to the source frequency sweep pattern. The salient information of the gas absorption due to the oscillation of the resonant frequency of the cavity is carried by the "dither'' signal and amplified and extracted by a series of tuned amplifiers and demodulators. Although the device is still at the initial design stage, a working prototype has been constructed in order to test the feasibility of the novel asynchronous modulation technique. This was achieved by successfully demonstrating that the device operates in an expected manner to within a standard error of 8.3%. It is believed that this error largely results from mechanical components. The significance of this error is greatly reduced when the spectrometer is operated in a large signal scanning mode as is the case when we apply the "power saturation'' technique to measure the concentration of ethylene oxide in the resonant cavity. This measurement showed that there is a good linear correlation between the output signal and the concentration of ethylene oxide gas (to within a standard error of 4%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144422
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  • 2
    Electronic Resource
    Electronic Resource
    Comparative solvolytic reactivity of bay-region diol epoxides derived from dibenz[a,j]anthracene and dibenzacridines (1990)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 112 (1990), S. 1177-1185 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00159a044
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  • 3
    Electronic Resource
    Electronic Resource
    Bovine amelogenin message heterogeneity: alternative splicing and Y-chromosomal gene transcription (1992)
    s.l. : American Chemical Society
    Biochemistry 31 (1992), S. 8384-8388 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00150a036
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  • 4
    Electronic Resource
    Electronic Resource
    Identification of a new HLA-DPB1 allele (DPB1*5101) by oligotyping and nucleotide sequencing (1994)
    Springer
    Immunogenetics 40 (1994), S. 164-164 
    Details
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188183
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  • 5
    Electronic Resource
    Electronic Resource
    Host selectivity and the mediation of competition by the root hemiparasite Rhinanthus minor (1991)
    Springer
    Oecologia 86 (1991), S. 81-87 
    Details
    ISSN: 1432-1939
    Keywords: Competition ; Hemiparasitism ; Host selectivity ; Rhinanthus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rhinanthus minor (Yellow-rattle) was grown in replacement series mixtures with Lolium perenne and Trifolium repens. The hemiparasitic interaction resulted in Relative Yield Totals (the sum of the yields in mixture relative to those in monoculture) considerably above 2. The hemiparasite caused a greater decrease in the yield of the legume and also performed better on the legume, indicating that T. repens was a better host for R. minor than L. perenne under the experimental conditions. When L. perenne and T. repens were grown in binary mixture with or without R. minor the hemiparasite affected considerably the competitive relationship between the two species by selectively parasitizing the legume. The effect of R. minor on competition between the two species was, however, dependent upon the nutrient status of the soil: the higher the level of soil nitrogen the fewer haustorial connections were made with T. repens and the less was the depression in its yield. In another series of experiments in which Festuca rubra, Holcus lanatus and L. perenne were grown in various binary mixtures with or without R. minor it was also shown that the yield of a preferred host was depressed to the advantage of a non-preferred host. It is suggested that the mediation of competition by the hemiparasite provides a mechanism by which it might affect the structure and diversity of plant communities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317393
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  • 6
    Electronic Resource
    Electronic Resource
    The role of the hemiparasitic annual Rhinanthus minor in determining grassland community structure (1992)
    Springer
    Oecologia 89 (1992), S. 62-68 
    Details
    ISSN: 1432-1939
    Keywords: Rhinanthus ; Hemiparasitism ; Species diversity ; Community structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rhinanthus minor (yellow-rattle) is a widespread hemiparasitic plant of grassland habitats throughout Great Britain. It is usually considered to be indicative of species-rich grassland, but in a survey of 14 habitats throughout Britain it was found that R. minor at the time of flowering normally occupied relatively low-diversity patches within areas of high diversity as determined by the number of species, Simpson's Index and the Shannon-Wiener Index. Following the death of adult plants of R. minor in the summer it was shown that the pattern of species diversity changed such that by the time R. minor germinated in the following spring the differences between the areas containing and not containing R. minor were much less distinct. A perturbation experiment in which R. minor was removed from four sites indicated that the effect of the removal of R. minor on the development of community structure over the next year was to increase species diversity on three of the sites and decrease it on the fourth. Those species which responded to the removal of R. minor by an increase in abundance were shown to be preferred hosts. All three lines of evidence point to the fact R. minor has a significant effect on the species diversity of the communities in which it grows by selectively parasitizing components of the flora and modifying the competitive relationships between plants. However, as the communities generally responded to the removal of R. minor by an increase in diversity and as the general survey indicated that R. minor is generally associated with areas of low diversity it would appear that the plants which are selectively parasitized are generally not the competitive dominants in the community.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319016
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  • 7
    Electronic Resource
    Electronic Resource
    A comparison of sedimentary and diatom-inferred phosphorus profiles: implications for defining pre-disturbance nutrient conditions (1993)
    Springer
    Hydrobiologia 253 (1993), S. 357-366 
    Details
    ISSN: 1573-5117
    Keywords: weighted averaging ; calibration ; phosphorus ; diatoms ; palaeolimnology ; Northern Ireland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Interpreting sedimentary phosphorus profiles in terms of changes in the historical P load is difficult due to variable retention and post-depositional diagenesis. An alternative approach is to use diatom assemblages in surface sediments and derive a transfer function for epilimnetic SRP and total P concentrations using weighted average regression and calibration. The obtained relationship can then be applied to down-core changes in sedimentary diatom assemblages and diatom-inferred P (DI-P) used to assess historical changes in epilimnetic P-concentrations. A diatom-phosphorus calibration data set for 43 eutrophic lakes in Northern Ireland has been constructed and applied to two small eutrophic lakes (Lough Mann, White Lough). DI-total P (i.e. predicted) is highly correlated with observed TP (r 2 = 0.75) for the surface-sediment training data-set. The resultant changes in DI-P derived from application of the transfer function to down-core changes in diatom assemblages are compared to sedimentary P concentrations. The latter are highly variable, presumably due to redox-derived effects, while DI-P profiles are more readily interpretable, and agree with other stratigraphic records of lake eutrophication. The method offers a good possibility of defining pre-disturbance (i.e. natural) phosphorus concentrations in lakes with associated implications for lake-restoration programmes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00050761
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  • 8
    Electronic Resource
    Electronic Resource
    The fractionation of cell components in Oscillatoria agardhii: an audit of procedures (1993)
    Springer
    Hydrobiologia 268 (1993), S. 163-168 
    Details
    ISSN: 1573-5117
    Keywords: cyanophyte ; carbon partitioning ; lipid ; carbohydrate ; protein ; centrifugation ; autoclaving ; L:D cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carbon partitioning techniques for the separation of physiologically important macromolecules (lipid, carbohydrate and protein) need to be efficient if they are to yield meaningful estimates of carbon flow in macromolecular synthesis, as measured by [14C] bicarbonate incorporation techniques. However, the efficiency of partitioning is rarely checked. Using existing methods, we found highly variable extraction efficiency of these macromolecules particularly of carbohydrate from cells grown under light:dark regimes. We report on a highly reproducible modification to existing methods which involves autoclaving with 5% trichloroacetic acid and centrifugation to separate carbohydrate and protein fractions. The presence of a structural non-extractable carbohydrate pool is reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014051
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  • 9
    Electronic Resource
    Electronic Resource
    First-order invariants of Euclidean motions (1991)
    Springer
    Acta applicandae mathematicae 24 (1991), S. 233-251 
    Details
    ISSN: 1572-9036
    Keywords: 70B10 ; Kinematics ; invariants ; screws
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Let E(n) be the lie group of proper rigid motions of Euclidean n-space. The paper is concerned with the adjoint action of E(n) on its Lie algebra e(n), and the induced action on the Grassmannian of subspaces of e(n) of a given dimension. For the adjoint action, the authors list explicit generators for the ring of invariant polynomials. In the case n=3, of greatest physical interest, explicit finite invariant stratifications are given for the Grassmannians, providing a formal listing of the screw-systems familiar in theoretical kinematics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00047045
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  • 10
    Electronic Resource
    Electronic Resource
    On the Hierarchy of screw systems (1993)
    Springer
    Acta applicandae mathematicae 32 (1993), S. 267-296 
    Details
    ISSN: 1572-9036
    Keywords: 70B10 ; Screw ; kinematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract LetE(3) be the Lie group of proper rigid motions of Euclidean 3-space. The adjoint action ofE(3) on its Lie algebrae(3) induces an action on the Grassmannian of subspaces of given dimensiond. Projectively, these subspaces are the screw systems of classical kinematics. The authors show that existing classifications of screw systems give rise to Whitney regular stratifications of the Grassmannians, and establish diagrams of specialisations for the strata. A list is given of the screw systems which can appear generically for motions of 3-space with at most three degrees of freedom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01082452
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