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  • 1
    Electronic Resource
    Electronic Resource
    The use of Hoare's method of program verfification for the quicksort algorithm (1977)
    Springer
    Computing 18 (1977), S. 281-293 
    Details
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Die vorliegende Arbeit analysiert die Erfahrungen, die bei der Durchführung formaler Korrektheitsbeweise an schon exsiterenden Programmen gemacht wurden. Mit Hilfe der Hoareschen Methode der Programmverfikation wurde der von an Emden angegebene Quicksort Algorithmus als richtig bewiesen. Dafür was es jedoch notwendig, eine Reihe von Veränderungen an dem Algorithmus vorzunehmen, um ihn an das Beweisverfahren und die existierenden Axiome anzupassen. Die gegenseitige Einflußnahme der Veränderungen und des Beweisverfahrens werden analysiert und Schlüse über die Verwendbarkeit des Hoareschen Verifikationsverfahrens für existierende Programme werden gezogen.
    Notes: Abstract Using the Quicksort Algortihm, given by van Emden, an analysis is made how Hoare's method of program verification can be applied to already existing programs. Changes to these programs become necessary to adopt them to the proving method and to the existing axioms. The interdependencies between these changes and the verification method are discussed and conclusions are draw about the applicability of Hoare's Methods for proving already existing programs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244016
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  • 2
    Electronic Resource
    Electronic Resource
    Ethics and the unintended consequences of social research: A perspective from the sociology of science (1977)
    Springer
    Policy sciences 8 (1977), S. 111-124 
    Details
    ISSN: 1573-0891
    Source: Springer Online Journal Archives 1860-2000
    Topics: Political Science , Economics
    Notes: Abstract It is argued that “successful” social science requires the development of a social ethic or sense of research responsibility. An examination of impediments to ethical reflection in sociology suggests that an individualistic orientation is ineffective in coping with the unintended consequences of social research. Such consequences can be particularly harmful in the sociology of science where policy research and governmental support for its production often entails an “indiscriminate advocacy of knowledge.” Such advocacy raises anew questions of the power of scientific knowledge, the definition of client-professional relationships, and the collection of data which may not only violate the intent of individuals and groups supplying information, but may undermine the credibility of sociology itself.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01712288
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  • 3
    Electronic Resource
    Electronic Resource
    Boundary conditions for quantum mechanics on cones and fields around cosmic strings (1991)
    Springer
    Communications in mathematical physics 139 (1991), S. 103-139 
    Details
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We study the options for boundary conditions at the conical singularity for quantum mechanics on a two-dimensional cone with deficit angle ≦ 2π and for classical and quantum scalar fields propagating with a translationally invariant dynamics in the 1+3 dimensional spacetime around an idealized straight infinitely long, infinitesimally thin cosmic string. The key to our analysis is the observation that minus-the-Laplacian on a cone possesses a one-parameter family of selfadjoint extensions. These may be labeled by a parameterR with the dimensions of length—taking values in [0, ∞). ForR=0, the extension is positive. WhenR≠0 there is a bound state. Each of our problems has a range of possible dynamical evolutions corresponding to a range of allowedR-values. They correspond to either finite, forR=0, or logarithmically divergent, forR≠0, boundary conditions at zero radius. Non-zeroR-values are a satisfactory replacement for the (mathematically ill-defined) notion of δ-function potentials at the cone's apex. We discuss the relevance of the various idealized dynamics to quantum mechanics on a cone with a rounded-off centre and field theory around a “true” string of finite thickness. Provided one is interested in effects at sufficiently large length scales, the “true” dynamics will depend on the details of the interaction of the wave function with the cone's centre (/field with the string etc.) only through a single parameterR (its “scattering length”) and will be well-approximated by the dynamics for the corresponding idealized problem with the sameR-value. This turns out to be zero if the interaction with the centre is purely gravitational and minimally coupled, but non-zero values can be important to model nongravitational (or non-minimally coupled) interactions. Especially, we point out the relevance of non-zeroR-values to electromagnetic waves around superconducting strings. We also briefly speculate on the relevance of theR-parameter in the application of quantum mechanics on cones to 1+2 dimensional quantum gravity with massive scalars.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02102731
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  • 4
    Electronic Resource
    Electronic Resource
    U(1)×SU(2)-gauge invariance of non-relativistic quantum mechanics, and generalized Hall effects (1992)
    Springer
    Communications in mathematical physics 148 (1992), S. 553-600 
    Details
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We show that the non-relativistic quantum mechanics of particles with spin coupled to an electromagnetic field has a naturalU(1)×SU(2) gauge invariance. Ward identities reflecting this gauge invariance combined with an assumption of incompressibility of a system of such particles in an appropriate external field and for suitable values of the particle density permit us to determine the form of the effective action of the system as a functional of small fluctuations in the electromagnetic field, in the large-distance-, adiabatic limit. In this limit, the action is found to have a universal form. We present explicit results for two-dimensional, incompressible electron fluids and apply them to derive the equations of linear response theory, describing a variety of generalized Hall effects. Sum rules for the Hall conductivities, magnetic susceptibilities and other quantities of physical interest are found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02096549
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  • 5
    Electronic Resource
    Electronic Resource
    High-pressure freezing of soybean nodules leads to an improved preservation of ultrastructure (1992)
    Springer
    Planta 188 (1992), S. 155-163 
    Details
    ISSN: 1432-2048
    Keywords: Bradyrhizobium ; Electron microscopy ; Glycine (root nodules) ; High-pressure freezing ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High-pressure freezing of chemically untreated nodules of soybean (Glycine max (L.) Merr.), in sharp contrast to chemical fixation and prefixation, appears to preserve the ultrastructure close to the native state. This is supported by the observation that the peribacteroid membrane of high-pressure-frozen samples is tightly wrapped around the bacteroids, a finding that is fully consistent with the current views on the physiology of oxygen and metabolite transport between plant cytosol and bacteroids. In soybean root nodules, the plant tissue and the enclosed bacteria are so dissimilar that conventional aldehyde-fixation procedures are unable to preserve the overall native ultrastructure. This was demonstrated by high-pressure freezing of nodules that had been pre-fixed in glutaraldehyde at various buffer molalities: no buffer strength tested preserved all ultrastructural aspects that could be seen after high-pressure freezing of chemically untreated nodules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216809
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  • 6
    Electronic Resource
    Electronic Resource
    Transport of volatile chlorinated hydrocarbons in unsaturated aggregated media (1993)
    Springer
    Water, air & soil pollution 68 (1993), S. 291-305 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Transport of volatile hydrocarbons in soils is largely controlled by interactions of vapours with the liquid and solid phase. Sorption on solids of gaseous or dissolved compounds may be important. Since the contact time between a chemical and a specific sorption site can be rather short, kinetic or mass-transfer resistance effects may be relevant. An existing mathematical model describing advection and diffusion in the gas phase and diffusional transport from the gaseous phase into an intra-aggregate water phase is modified to include linear kinetic sorption on gas-solid and water-solid interfaces. The model accounts for kinetic mass transfer between all three phases in a soil. The solution of the Laplace-transformed equations is inverted numerically. We performed transient column experiments with 1,1,2-Trichloroethane, Trichloroethylene, and Tetrachloroethylene using air-dry solid and water-saturated porous glass beads. The breakthrough curves were calculated based on independently estimated parameters. The model calculations agree well with experimental data. The different transport behaviour of the three compounds in our system primarily depends on Henry's constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00479409
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of calcium ionophores on the transport and distribution of calcium in isolated cells and in liver and kidney slices (1978)
    Springer
    The journal of membrane biology 38 (1978), S. 51-72 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of calcium ionophores on cellular calcium metabolism were studied in cultured kidney cells, in cells freshly isolated from rat kidney, and in liver and kidney slices. In isolated cells, these ionophores decreased the total cellular Ca content and the mitochondrial Ca.45Ca efflux from prelabelled cells was also stimulated even in the absence of extracellular Ca. In slices, the ionophore A23187 increased the total slice Ca and the uptake of45Ca. However, the mitochondria isolated from these slices treated with the ionophore had a lower total Ca and a depressed relative radioactivity. These results suggest that the increased cytosolic Ca produced by Ca ionophores may be due to mobilization of intracellular Ca stores rather than to a net shift of Ca from the extracellular fluids to the cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01875162
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of pH on the calcium metabolism of isolated rat kidney cells (1979)
    Springer
    The journal of membrane biology 48 (1979), S. 325-341 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of metabolic and respiratory acidosis and alkalosis on cellular calcium metabolism were studied in rat kidney cells dispersed with collagenase. In both types of acidosis, the intracellular pH, total cell calcium, and the cell relative radioactivity after 60 min of labeling are significantly depressed. Kinetic analysis of45Ca desaturation curves shows that acidosis decreases all three cellular calcium pools and depresses calcium fluxes between the superficial and cytosolic pools and between the cytosolic and mitochondrial pools. In alkalosis the intracelluar pH, the total cell calcium, and the cell relative radioactivity are significantly increased. Kinetic studies show that in alkalosis, only the mitochondrial pool is consistently increased. Calcium exchange between the mitochondrial and cytosolic pool is increased in metabolic alkalosis only. These results suggest that hydrogen ion is an important modulator of calcium metabolism, and that the intracellular pH rather than extracellular pH is the critical factor in determining the calcium status of cells during altered acid-base conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869444
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  • 9
    Electronic Resource
    Electronic Resource
    Two-dimensional spin freezing in Y1−z Ca z Ba2Cu3−x Fe x O7 (1993)
    Springer
    Hyperfine interactions 77 (1993), S. 277-299 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Hyperfine electric and magnetic interactions in Y1−z Ca z Ba2Cu3−x Fe x O6+y compounds have been studied for different rates of Fe and Ca substitution (x=0.09 and 0.24;z=0.24;y=0−1) by57Fe Mössbauer spectroscopy of powder samples obtained by different thermal treatments. Calculations of the Fe3+ EFG tensor have been performed for different coordination polyhedra in Cu1 and Cu2 sites. Variations of the direction, amplitude and of the sign of the principal component of the EFG are reported versus the iron displacement from the ideal Cu sites inside the pyramidal and tetrahedral coordination polyhedra. Calculated ΔE Q and η values are compared with the experimental ones. For the Cu2 site, faithfully probed in both oxygen-depleted and oxygen-saturated samples by fairly large fraction of residing iron atoms, the mutual orientations of the axes of the principal EFG component and that of easiest magnetization are deduced from interrelations between quadrupole parameters for paramagnetic quadrupolar and magnetic Zeeman Mössbauer spectra. In the desoxygenated samples, the coexistence of a long range 2D antiferromagnetic order and of a spin-glass order has been evidenced. For the oxygen-saturated samples, the two-dimensional spin-glass order is observed belowT f =10 K. The Mössbauer spectra under applied fields at 4.2 K show an easy polarization of the spins in the Cu2 sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02320318
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  • 10
    Electronic Resource
    Electronic Resource
    Knowledge and structures of scientific growth measurement of a cancer problem domain (1979)
    Springer
    Scientometrics 1 (1979), S. 171-193 
    Details
    ISSN: 1588-2861
    Source: Springer Online Journal Archives 1860-2000
    Topics: Information Science and Librarianship , Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract In the context of bridging the so-called externalist and cognitive perspectives on the growth of research communities, a cancer “problem domain” is examined (1) to distinguish a growth in knowledge from a proliferating research literature, and (2) show how measurement of formal communication, uninformed by the “historical record,” clarifies or distorts sociological interpretations of innovation and growth in biomedicine. Specifically, coauthorship and citation networks are analyzed for reverse transcriptase researchers, 1970–74. This analysis reveals the visibility of large National Cancer Institute laboratories in the research literature, but demonstrates the need to augment disaggregated network data with intellectual and social (policy) history to explain the growth and structure of the domain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02016969
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