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  • 1
    Electronic Resource
    Electronic Resource
    Quaternion symmetry in relativistic molecular calculations: The Dirac–Hartree–Fock method (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 6211-6222 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A symmetry scheme based on the irreducible corepresentations of the full symmetry group of a molecular system is presented for use in relativistic calculations. Consideration of time-reversal symmetry leads to a reformulation of the Dirac–Hartree–Fock equations in terms of quaternion algebra. Further symmetry reductions due to molecular point group symmetry are then manifested by a descent to complex or real algebra. Spatial symmetry will be restricted to D2h and subgroups, and it will be demonstrated that the Frobenius–Schur test can be used to characterize these groups as a whole. The resulting symmetry scheme automatically provides maximum point group and time-reversal symmetry reduction of the computational effort, also when the Fock matrix is constructed in a scalar basis, that is, from the same type of electron repulsion integrals over symmetry-adapted scalar basis functions as in nonrelativistic theory. An illustrative numerical example is given showing symmetry reductions comparable to the nonrelativistic case. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479958
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  • 2
    Electronic Resource
    Electronic Resource
    On the origin and contribution of the diamagnetic term in four-component relativistic calculations of magnetic properties (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 6208-6218 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The relativistic Dirac Hamiltonian that describes the motion of electrons in a magnetic field contains only paramagnetic terms (i.e., terms linear in the vector potential A) while the corresponding nonrelativistic Schrödinger Hamiltonian also contains diamagnetic terms (i.e., those from an A2 operator). We demonstrate that all diamagnetic terms relativistically arise from second-order perturbation theory and that they correspond to a "redressing" of the electrons by the magnetic field. If the nonrelativistic limit is taken with a fixed no-pair Hamiltonian (no redressing), the diamagnetic term is missing. The Schrödinger equation is normally obtained by taking the nonrelativistic limit of the Dirac one-electron equation, we show why nonrelativistic use of the A2 operator is also correct in the many-electron case. In nonrelativistic approaches, diamagnetic terms are usually considered in first-order perturbation theory because they can be evaluated as an expectation value over the ground state wave function. The possibility of also using an expectation value expression, instead of a second-order expression, in the relativistic case is investigated. We also introduce and discuss the concept of "magnetically balanced" basis sets in relativistic calculations. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479181
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  • 3
    Electronic Resource
    Electronic Resource
    Deposition of boron-nitride films by nitrogen sputtering from a boron-metal target (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1489-1491 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This contribution deals with reactive growth of boron-nitride films by a rf nitrogen-sputtering process from a boron-metal target; thus nitrogen is functioning both as sputter and reactive gas. Only few and superficial reports of reactive sputter depositions from a metallic boron target in various argon/nitrogen mixtures exist, compared to the number of reports on rf sputtering from a BN target. Nitrogen sputtering of boron-metal has previously not been reported. It was shown by Fourier-transform infrared (FTIR) spectroscopy that the hexagonal structure of BN exclusively was deposited. Sputter rates were measured and showed no dependence on the reactive-gas flow and only a marginal dependence on sputter-gas mixtures containing 20% of krypton, argon, or helium. The reported nitrogen-sputtering process appears to be appropriate for exploration of the key parameters for phase control in BN growth and for additional surface engineering processes such as substrate bias and post-ion bombardment. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113664
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  • 4
    Electronic Resource
    Electronic Resource
    Efficacy of Ki-67 antigen staining in Papanicolaou (Pap) smears in post-menopausal women with atypia—an audit (1999)
    Oxford, UK : Blackwell Science Ltd
    Cytopathology 10 (1999), S. 0 
    Details
    ISSN: 1365-2303
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In cervical smears from post-menopausal women with mucosal atrophy it can be difficult to distinguish atrophic epithelial cell groups from neoplastic cell groups on cytomorphological criteria only. The consequence of post-menopausal atypia is that the woman is referred for a repeat smear after local oestrogen treatment or for colposcopy. We investigated whether immunocytochemical expression of Ki-67 (MIB-1) on the primary Papanicolaou-stained smear could be of any diagnostic help. Our data showed that negative Ki-67 expression is a very reliable indicator of a normal atrophic cell pattern, and by using this method on the original smear we were able to reduce the false-positive cytologic diagnoses by 86%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2303.1999.00205.x
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetics of nitrate and ammonium absorption and accompanying H+ fluxes in roots of Lolium perenne L. and N2-fixing Trifolium repens L. (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 20 (1997), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Kinetic parameters for NH4+ and NO3− uptake were measured in intact roots of Lolium perenne and actively N2-fixing Trifolium repens. Simultaneously, net H+ fluxes between the roots and the root medium were recorded, as were the net photosynthetic rate and transpiration of the leaves. A Michaelis–Menten-type high-affinity system operated in the concentration range up to about 500 mmol m−3 NO3− or NH4+. In L. perenne, the Vmax of this system was 9–11 and 13–14 μmol g−1 root FW h−1 for NO3− and NH4+, respectively. The corresponding values in T. repens were 5–7 and 2 μmol g−1 root FW h−1. The Km for NH4+ uptake was much lower in L. perenne than in T. repens (c. 40 compared with 170 mmol m−3), while Km values for NO3− absorption were roughly similar (around 130 mmol m−3) in the two species. There were no indications of a significant efflux component in the net uptake of the two ions. The translocation rate to the shoots of nitrogen derived from absorbed NO3−-N was higher in T. repens than in L. perenne, while the opposite was the case for nitrogen absorbed as NH4+. Trifolium repens had higher rates of transpiration and net photosynthesis than L. perenne. Measurements of net H+ fluxes between roots and nutrient solution showed that L. perenne absorbing NO3− had a net uptake of H+, while L. perenne with access to NH4+ and T. repens, with access to NO3− or NH4+, in all cases acidified the nutrient solution. Within the individual combinations of plant species and inorganic N form, the net H+ fluxes varied only a little with external N concentration and, hence, with the absorption rate of inorganic N. Based on assessment of the net H+ fluxes in T. repens, nitrogen absorption rate via N2 fixation was similar to that of inorganic N and was not down-regulated by exposure to inorganic N for 2 h. It is concluded that L. perenne will have a competitive advantage over T. repens with respect to inorganic N acquisition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1997.d01-145.x
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  • 6
    Electronic Resource
    Electronic Resource
    Localization of a resistance gene and identification of sources of resistance to barley leaf stripe (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 116 (1997), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: In order to determine more precisely the location of the barley leaf stripe gene, called the ‘Vada-resistance gene’, on barley chromosome 2, 63 chromosome-doubled barley lines were tested. Using data on known chromosome 2 genetic markers, the ‘Vada-resistance gene’ was estimated to be located between the markers MSU21 and Xris45b, and at a distance of about 20% recombination from the powdery mildew resistance gene MILa. We suggest that the ‘Vada-resistance gene’ is designated Rdg1a and that all former leaf stripe resistance gene designations should be rejected.To identify possible new sources of resistance, 11 barley cultivars/lines known to possess leaf stripe resistance and originating from different parts of the world, were tested with one Danish and two Syrian isolates of the leaf stripe fungus. Three apparently genetically different sources of race-specific resistance were found. The ‘Vada-resistance’ in the cultivar ‘Golf was effective against seven out of eight isolates’ populations of the leaf stripe fungus differing in geographical origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1997.tb01030.x
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  • 7
    Electronic Resource
    Electronic Resource
    A Japanese powdery mildew isolate with exceptionally large infection efficiency on Mlo-resistant barley (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 44 (1995), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A Japanese field isolate (Race I) of Erysiphe graminis f.sp, hordei was tested on 17 barley lines carrying the mlo powdery mildew resistance gene. Race I produced many successful infections with infection type larger than or equal to 2 on six lines (M66, MC20, SRI, SR7, A tem and Totem), On the remaining 11 lines it reacted with infection type 0. Colony numbers on the Mlo-lines were between 26% and 12 9% of the numbers on a susceptible cultivar Manchuria, These numbers were larger than, or similar to those produced by isolate HL3/5, which has the highest recorded infection efficiency on Mlo-resistant cultivars. The interaction between isolates and lines was highly significant. The isolate GE3, from which HL3/5 was derived by selection, gave rise to occasional colonies corresponding to less than 03° o of the number produced on cv. Manchuria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3059.1995.tb02736.x
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  • 8
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    Degering, H.: Die Schrift (Book Review) (1930)
    Berlin : Periodicals Archive Online (PAO)
    Orientalistische Literaturzeitung. 33 (1930) 863 
    Details
    ISSN: 0030-5383
    Topics: Linguistics and Literary Studies , Ethnic Sciences , History
    Notes: Besprechungen
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:4148-1930-033-00-000123
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  • 9
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    Mironov, N. D.: Kuchean Studies. I (Book Review) (1930)
    Berlin : Periodicals Archive Online (PAO)
    Orientalistische Literaturzeitung. 33 (1930) 1022 
    Details
    ISSN: 0030-5383
    Topics: Linguistics and Literary Studies , Ethnic Sciences , History
    Notes: Besprechungen
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:4148-1930-033-00-000319
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  • 10
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    Wheeler, L. R.: The Modern Malay (Book Review) (1930)
    Berlin : Periodicals Archive Online (PAO)
    Orientalistische Literaturzeitung. 33 (1930) 928 
    Details
    ISSN: 0030-5383
    Topics: Linguistics and Literary Studies , Ethnic Sciences , History
    Notes: Besprechungen
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:4148-1930-033-00-000498
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