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  • 1
    Digitale Medien
    Digitale Medien
    A prospective trial of computed tomography in the staging of ovarian malignancy (1985)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 92 (1985), S. 0 
    Details
    ISSN: 1471-0528
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Summary. Thirty patients, thought clinically to have ovarian tumours, were studied prospectively by pre-operative computed tomographic (CT) scans of the abdomen and pelvis. In six patients (20%) small metastases in mesentery, omentum and on subdiaphragmatic peritoneum were not detected by the scans. CT did not improve the accuracy of staging or assist the surgeons by drawing their attention to disease which they might otherwise have missed. Although CT gives an elegant demonstration of anatomy, it is not an alternative to extended laparotomy in patients with ovarian tumours.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-0528.1985.tb01116.x
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  • 2
    Digitale Medien
    Digitale Medien
    Relativistic and nonrelativistic plasma dispersion functions (1989)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 30 (1989), S. 2484-2487 
    Details
    ISSN: 1089-7658
    Quelle: AIP Digital Archive
    Thema: Mathematik , Physik
    Notizen: A number of new results involving the functions that determine the emission, dispersion, and absorption of waves in nonrelativistic and weakly relativistic plasmas are presented. These results comprise series, integrals, recursion relations, symmetry properties, interrelations, approximations, and connections with standard transcendental functions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.528528
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  • 3
    Digitale Medien
    Digitale Medien
    Conditions for the validity of unmagnetized-plasma theory in describing weakly magnetized plasmas (1988)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 31 (1988), S. 525-534 
    Details
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: An investigation is made of the conditions under which the expression for the dielectric tensor from magnetized-plasma theory may be approximated by that from unmagnetized-plasma theory. Surprisingly, the conditions usually quoted are shown to be inaccurate chiefly because they make no reference to the form of the plasma distribution function. Corrected conditions depend strongly on the distribution function and their application is thus highly problem-dependent. For completely arbitrary distributions these conditions are generally stronger than the commonly quoted ones for weakly damped waves. By contrast, the conditions applicable to axisymmetric distributions can be weaker than some of those commonly quoted. A geometric interpretation of the revised conditions for axisymmetric distributions is given in terms of the resonance ellipses of cyclotron maser theory and is illustrated with reference to dispersion and instability of Langmuir and Bernstein waves in weakly magnetized plasmas. These results apply to all weakly magnetized plasmas that can be described by the linearized Vlasov equations and imply that some investigations which have used the commonly quoted conditions to justify use of unmagnetized-plasma theory may be in error on this point.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.866834
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  • 4
    Digitale Medien
    Digitale Medien
    Weakly relativistic dispersion of Bernstein waves (1988)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 31 (1988), S. 107-114 
    Details
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Weakly relativistic effects on the dispersion of Bernstein waves are investigated for waves propagating nearly perpendicular to a uniform magnetic field in a Maxwellian plasma. Attention is focused on those large-wave-vector branches that are either weakly damped or join continuously onto weakly damped branches since these are the modes of most interest in applications. The transition between dispersion at perpendicular and oblique propagation is examined and major weakly relativistic effects on dispersion at perpendicular propagation are found to persist at other angles; these effects can dominate even in low-temperature plasmas. A number of simple analytic criteria are obtained which delimit the ranges of harmonic number and propagation angle within which various types of weakly damped Bernstein modes can exist.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.866557
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  • 5
    Digitale Medien
    Digitale Medien
    Relativistic plasma dispersion functions: Series, integrals, and approximations (1987)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 28 (1987), S. 1203-1205 
    Details
    ISSN: 1089-7658
    Quelle: AIP Digital Archive
    Thema: Mathematik , Physik
    Notizen: A number of results are presented involving the plasma dispersion functions appropriate to waves in weakly relativistic, magnetized, thermal plasmas. These results include generating functions, series, integral forms and interrelations, and several useful approximations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.527515
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  • 6
    Digitale Medien
    Digitale Medien
    Relativistic plasma dispersion functions (1986)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 27 (1986), S. 1206-1214 
    Details
    ISSN: 1089-7658
    Quelle: AIP Digital Archive
    Thema: Mathematik , Physik
    Notizen: The known properties of plasma dispersion functions (PDF's) for waves in weakly relativistic, magnetized, thermal plasmas are reviewed and a large number of new results are presented. The PDF's required for the description of waves with small wave number perpendicular to the magnetic field (Dnestrovskii and Shkarofsky functions) are considered in detail; these functions also arise in certain quantum electrodynamical calculations involving strongly magnetized plasmas. Series, asymptotic series, recursion relations, integral forms, derivatives, differential equations, and approximations for these functions are discussed as are their analytic properties and connections with standard transcendental functions. In addition a more general class of PDF's relevant to waves of arbitrary perpendicular wave number is introduced and a range of properties of these functions are derived.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.527127
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  • 7
    Digitale Medien
    Digitale Medien
    New contributions to transit-time damping in multidimensional systems (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 490-498 
    Details
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The existence of two previously unrecognized contributions to transit-time damping in systems of more than one dimension is demonstrated and discussed. It is shown that these contributions cannot be treated by one-dimensional analyses unless it is assumed that the gradient of the field perpendicular to itself always vanishes. Such an assumption is unjustified in general and the new contributions can dominate damping by fast particles in more general situations. Analytic expressions obtained using a Born approximation are found to be in excellent agreement with numerical test-particle calculations of transit-time damping for a variety of field configurations. These configurations include those of a resonance layer and of a spherical wave packet, which approximates a collapsing wave packet in a strongly turbulent plasma. It is found that the fractional power absorption can be strongly enhanced in non-slablike field configurations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.859164
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  • 8
    Digitale Medien
    Digitale Medien
    Quasiperiodic behavior in beam-driven strong Langmuir turbulence (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 2319-2329 
    Details
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The evolution of unmagnetized beam-driven strong Langmuir turbulence is studied in two dimensions by numerically integrating the Zakharov equations for systems pumped by monochromatic and broadband negative-damping drivers with nonzero central wavenumber. Long-time statistically steady states are reached for which the dependence of the evolution on the driver wavenumber, growth rate, and bandwidth is examined in detail. For monochromatic drivers, a quasiperiodic cycle is found to develop if the driver wavenumber is sufficiently large. In this cycle, energy from the driven mode undergoes a sequence of weak-turbulence backscatter decays, which transfer energy to an approximately isotropic long-wavelength condensate. During this phase, beam-aligned chains of propagating beat waves develop and perpendicular density waves are also excited. Subsequently, nucleation of waves in density cavities causes a series of wave collapses (involving coherent wave–wave interactions) to occur, during which short-wavelength damping reduces the system energy in discrete steps. Finally, the cycle restarts. The characteristic frequency of the quasiperiodic cycle and the average system energy are both approximately proportional to the growth rate. Broadening of the driver in wavenumber tends to degrade the system-wide coherence of the cycle, but its main features appear to survive on the scale of the coherence length of the driver.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.859050
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  • 9
    Digitale Medien
    Digitale Medien
    Effects of annealing on TlBaCaCuO thin films (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 660-662 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have studied the effects of high-temperature anneals on sequentially deposited TlBaCaCu films in an environment containing O2 and TlOx . From Auger electron spectroscopy depth profiles, it was found that Tl was quite volatile and can be easily eliminated from the thin films after a short treatment at 830 °C. However, the Tl can be incorporated in the films after appropriate treatment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.100911
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  • 10
    Digitale Medien
    Digitale Medien
    Physical properties of periodontal dressing materials (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of oral rehabilitation 13 (1986), S. 0 
    Details
    ISSN: 1365-2842
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The purpose of this study was to develop standardized reproducible testing methods for evaluating physical properties of periodontal dressing materials. Three commercial compositions (Coe-Pak, Coe-Pak Hard & Fast Set and WondrPak) were studied.Working and setting times were determined by observing the continuous changes in viscosity via the oscillating rheometer. The 24-h and 1-week tensile and shear adhesive bonds to enamel were studied by luting orthodontic lingual cleats with a standard film thickness to the orientated labial surfaces of extracted incisors and pulling them to failure. Dimensional change was studied over a period of 24h using a linear variable differential transformer (LVDT).The developed testing modalities have greater precision than those previously reported. The concept of ‘bench time’ was developed during which certain materials cannot be handled immediately after mixing.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2842.1986.tb00681.x
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