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  • 1
    ISSN: 1432-0649
    Keywords: 33 ; 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Letters in mathematical physics 15 (1988), S. 205-212 
    ISSN: 1573-0530
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We show that linear Hermitian supplementary conditions can never be imposed in a representation associated with a regular state on the C *-algebra of the CCRs. Nevertheless, there is a well-defined method for imposing the constraints in an abstract C *-framework, which yields as its final physical algebra a CCR C *-algebra, on which one can again require its physical states to be regular. These states derive from states on the original C *-algebra which are ‘regular up to nonphysical quantities’.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-0832
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present paper reports our attempts to determine whether the inclusion of 0.0014 mM Zn++ within a hydroponic culture medium affects the ability of 12-day-old Zea mays, cv. ‘SS-522’ to take-up [3H]-aflatoxin B1. Data from the corollary experiment, i.e., whether inclusion of aflatoxin affects the ability of Zea mays, cvs. ‘Truckers White’, ‘X-Sweet’ and ‘Merit’ to take-up 65ZnCl2 are presented also. This report is a preliminary to one regarding an in-progress analysis of whether pollutant levels of Zn++ affect aflatoxin uptake and distribution. In the absence of irrigating seedlings, which were grown in Perlite containing 65ZnCl2, with a solution containing mixed aflatoxins, the stem contained the greatest amount of label with root plus seed the next highest and the leaf the least for each of the cvs. In contrast, when the seedlings were irrigated with a solution containing mixed aflatoxins, the root plus seed contained either an amount nearly identical to (cv. ‘Truckers White’) or in excess of that within the stem (cvs. ‘X-Sweet’ and ‘Merit’). Calculation of the percentages of aflatoxin-induced diminutions in leaf, stem and root label suggested that the aflatoxins interfered with the translocation of 65ZnCl2 from the root to the stem and leaf, at least for cvs ‘X-Sweet’ and ‘Merit’. When 0.0014mM Zn++ as ZnSO4 was added to an incubation medium in which 12-day-old seedlings were suspended and plant growth assessed over 72 hours, a 15% increase (significant at 0.05 level) in seedling height over that of Zn++-deficient plants was observed. No differences in [3H]-aflatoxin B1 uptake were noted between those seedlings which were grown in either Zn++-containing or lacking media. Less than one % of the[3H]-aflatoxin B1 which was taken-up was recovered within chloroform extracts of the seedlings. The distributions of radioactivity from [3H]-aflatoxin B1 for leaf, stem, seed and root were 0, 57, 26 and 19% and 0, 26, 58 and 18% for Zn++-containing and -lacking media, ‘respectively’.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0592
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography , Economics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 45 (1988), S. 301-304 
    ISSN: 1432-0630
    Keywords: 42.60 ; 82.50N ; 85.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract KrF laser etching of GaAs in Cl2 and O3 gas ambients by direct laser illumination is reported. The etch depth per pulse in Cl2 was found to be linear versus the laser fluence on the sample in the 0.2–1.1 J/cm2 range. It increased as a function of the Cl2 pressure up to 6 Torr and slightly decreased for pressures above this value. It also decreased as a function of the laser repetition rate. Very smoothly etched surfaces were obtained after irradiation using the Cl2 and O3 etching gases. Auger analysis of the etched GaAs surfaces shows almost no traces of chlorine after etching in Cl2, whereas a thick oxide layer of about 1500 Å thickness was found after etching in ozone.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Environmental geology 3 (1981), S. 363-367 
    ISSN: 1432-0495
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Fly ash generated by coal-fired power plants is in part collected by filters in the emission stacks while a small portion is vented into the atmosphere. Since many of the coalfired power plants in the western United States are located in the desnrt, the ability to monitor fly ash emissions requires a chemical tracer that utilizes desert soil and plant interactions with the fly ash deposited in the desert environment. This investigation presents the results of a controlled greenhouse experiment in which a native desert plant, the brittlebush (Encelia farinosa), was grown on admixtures of desert soils and fly ash. The fly ash is strongly enriched in Sr and the brittlebush is a Sr accumulator. The data demonstrate that (1) the brittlebush isotopically equilibrates with desert soils whose fly ash components are as low as 0.25% by weight, (2) the fly ash Sr is apparently more available to the plant, than Sr derived from the soils, and (3) the difference between the87Sr/86Sr ratio of the fly ash (0.70807) and soils (0.71097 to 0.71117) warrants further investigations in the natural environment to determine the practicality of this method as a natural tracer of fly ash in the environment.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 119 (1988), S. 75-93 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The problem of second class quantum constraints is here set up in the context ofC*-algebras, utilizing the connection with state conditions as given by the heuristic quantization rules. That is, a constraint set is said to be first class if all its members can satisfy the same state condition, and second class otherwise. Several heuristic models are examined, and they all agree with this definition. Given then a second class constraint set, we separate out its first class part as all those constraints which are compatible with the others, and we propose an algebraic construction for imposition of the constraints. This construction reduces to the normal one when the constraints are first class. Moreover, the physical automorphisms (assumed as conserving the constraints) will also respect this construction. The final physical algebra obtained is free of constraints, gauge invariant, unital, and with the right choice, simple. ThisC*-algebra also contains a factor algebra of the usual observables, i.e. the commutator algebra of the constraints. The general theory is applied to two examples—the elimination of a canonical pair from a boson field theory, as in the two dimensional anomalous chiral Schwinger model of Rajaraman [14], and the imposition of quadratic second class constraints on a linear boson field theory.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 80 (1981), S. 1-21 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract If cutoffs are introduced then existing results in the literature show that the Schwinger model is dynamically equivalent to a boson model with quadratic Hamiltonian. However, the process of quantising the Schwinger model destroys local gauge invariance. Gauge invariance is restored by the addition of a counterterm, which may be seen as a finite renormalisation, whereupon the Schwinger model becomes dynamically equivalent to a linear boson gauge theory. This linear model is exactly soluble. We find that different treatments of the supplementary (i.e. Lorentz) condition lead to boson models with rather different properties. We choose one model and construct, from the gauge invariant subalgebra, a class of inequivalent charge sectors. We construct sectors which coincide with those found by Lowenstein and Swieca for the Schwinger model. A reconstruction of the Hilbert space on which the Schwinger model exists is described and fermion operators on this space are defined.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 98 (1985), S. 369-390 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract Systems with a gauge degeneracy are characterized either by supplementary conditions, or by a set of generators of gauge transformations, or by a set of constraints deriving from Dirac's canonical constraint method. These constraints can be expressed either as conditions on the field algebra ℱ, or on the states on ℱ. In aC*-algebra framework, we show that the state conditions give rise to a factor algebra of a subalgebra of the field algebra ℱ. This factor algebra, ℛ, is free of state conditions. In this formulation we show also that the algebraic conditions can be treated in the same way as the state conditions. The connection between states on ℱ and states on ℛ is investigated further within this framework, as is also the set of transformations which are compatible with the set of constraints. It is also shown that not every set of constraints can give rise to a nontrivial system. Finally as an example, the abstract theory is applied to the electromagnetic field, and this treatment can be generalized to all systems of bosons with linear constraints. The question of dynamics is not discussed.
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