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  • 11
    Electronic Resource
    Electronic Resource
    Calculations on the Jahn–Teller configurations of the benzene cation (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 10550-10554 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The analysis of the zero-electron-kinetic-energy photoelectron spectra of benzene has led to a reinvestigation by ab initio methods of the electronic states of the C6H6+ cation resulting from Jahn–Teller distortions on ionization. The calculations involving a range of currently used methodologies all verify that the two cation configurations, 2B2g and 2B3g of D2h symmetry, resulting from removal of an electron from the e1g(π) degenerate MOs of C6H6, comprise a true minimum and a transition state, differing only slightly in energy. These are linked through the in-plane b1g vibration, confirming that b1g is actually a pseudorotational coordinate. Hence C6H6+ exhibits similar structural floppiness to the cations of methane and cyclopropane although with a much smaller barrier to pseudorotation than for these smaller species. These results support the general proposition that such Jahn–Teller distortions associated with molecular ionization (of stable closed-shell hydrocarbon molecules of high symmetry) generally involve a quadratic contribution which leads to a single global minimum cation structure, with all other derived stationary states being transition states each characterized by a single imaginary vibration frequency. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480407
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  • 12
    Electronic Resource
    Electronic Resource
    Theory of proton relaxation induced by superparamagnetic particles (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 5403-5411 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Evaluating and understanding the performances of magnetic colloids as contrast agents for MRI requires a theory describing their magnetic interactions with water protons. The field dependence of the proton longitudinal relaxation rate (nuclear magnetic relaxation dispersion profiles) in aqueous colloidal suspensions of superparamagnetic particles is based on the so-called Curie relaxation, which essentially accounts for the high field part of the NMRD profiles (B0〉0.02 T). The low-field part of the NMRD profiles can only be explained by the crystal's internal anisotropy energy, a concept which clarifies the important difference between superpara- and paramagnetic compounds: the anisotropy energy modifies both the electronic precession frequencies and the thermodynamic probability of occupation of the crystal magnetic states. Our theory clearly explains why a low-field dispersion exists for suspensions of small size crystals, and why it does not for large crystals' suspensions. This important effect is due to the Boltzmann factors depending on the anisotropy energy, which is itself proportional to the particle volume. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478435
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  • 13
    Electronic Resource
    Electronic Resource
    Enthusiastic Embrace or Critical Reception? The German HRM Debate (1999)
    Oxford, UK and Boston, USA : Blackwell Publishers Ltd
    Journal of management studies 36 (1999), S. 0 
    Details
    ISSN: 1467-6486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: This paper discusses the reception of human resource management (HRM) in Germany. A review of the German HRM debate shows that this is dominated by business administration academics specializing in this field. In the past, these scholars as well as practitioners have generally embraced the techniques as well as the ideology of HRM. This finding can be explained by a relatively low emphasis on empirical research, a neglect of industrial relations issues, and a strong impact of theories and concepts developed in the USA. Today, however, there appears to be a change towards a more critical appreciation of the US HRM model and a more positive assessment of the German HRM model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1467-6486.00145
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  • 14
    Electronic Resource
    Electronic Resource
    Transition and development of innovation capacities in Hungary (1996)
    Oxford, UK : Blackwell Publishing Ltd
    R & D management 26 (1996), S. 0 
    Details
    ISSN: 1467-9310
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: The paper attempts to synthesize the conclusions of theoretical works dealing with innovation processes and technological strategies in the frame of a national innovation system with some results from a survey of the national innovation system in Hungary.An important focus of the paper is on the transition situation in Hungary and the role science and technology play and are expected to play to influence the competitiveness of the country. Special attention is therefore given to the new actors in the system. The conclusions are expressed in the form of premises dealing with the multiple impacts of the transition on the Hungarian innovation system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1467-9310.1996.tb00935.x
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  • 15
    Electronic Resource
    Electronic Resource
    Study of nonlinear dibit interactions (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 4705-4707 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate isolated dibit interactions by varying the intradibit spacing and observing position fluctuations using a magnetic force microscope. We see that the measured dibit spacing deviates at a recording density that depends on the remanence–thickness product Mrδ of the medium. The increased dibit separation may be partially due to the demagnetization fields during write: we find that partial erasure annihilates the narrower crosstrack parts of the dibit, effectively inducing an increase in dibit separation. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370454
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  • 16
    Electronic Resource
    Electronic Resource
    Spin-stand measurements of time and temperature dependence of magnetic recordings (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 4994-4996 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spin-stand experiments were performed to study the effect of temperature and demagnetizing fields on the stability of magnetic recordings. Tracks of varying linear bit densities were written on a low Mrδ medium that was heated in situ to different temperatures. The readback amplitude, which reflects the changes in the magnetization of the recordings, was observed from 32 ms to 12 h after the tracks were written. The readback amplitude was found to decay with time. The rate of decay increased at higher densities due to higher demagnetizing fields. A further increase in the decay rate was observed at higher temperatures. This increase in decay rate exceeded that predicted by proportional temperature scaling. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370069
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  • 17
    Electronic Resource
    Electronic Resource
    Parameter identification for a micromagnetic recording medium model (abstract) : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4846-4846 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Many recent studies of recording and playback in magnetic recording systems have been based on the computer simulation of micromagnetic models of magnetic recording media. Medium models are capable of representing a large class of recording media by selection of appropriate values of model parameters representing the intrinisic properties of the recording medium material. Such parameters include grain size, anisotropy energy density, and exchange energy constant. Largely missing in these studies, however, has been a discussion of how to identify a set of parameter values to represent a particular medium of interest. In this presentation, we describe an identification procedure for selecting the values of the five intrinsic parameters of a micromagnetic medium model to represent a recording medium for which the following hysteresis properties are known: remanent magnetization, coercivity, remanence squareness, and coercivity squareness. Calculation of hysteresis loops verifies that the particular instance of the medium model identified by this procedure reproduces the hysteresis behavior of the medium of interest. Comparison of computer simulations of recording operations to measured recording performance of a medium on a laboratory tester may then be meaningfully made.© 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364853
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  • 18
    Electronic Resource
    Electronic Resource
    Enhancement of Bacterial Mutagenicity of Bifunctional Alkylating Agents by Expression of Mammalian Glutathione S-Transferase (1995)
    s.l. : American Chemical Society
    Chemical research in toxicology 8 (1995), S. 465-472 
    Details
    ISSN: 1520-5010
    Source: ACS Legacy Archives
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/tx00045a019
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  • 19
    Electronic Resource
    Electronic Resource
    Flow regimes in model viscoelastic fluids in a circular couette system with independently rotating cylinders (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 9 (1997), S. 566-586 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Flow visualization of two highly elastic, nonshear-thinning polyisobutylene/polybutene fluids in the gap between concentric cylinders was performed over a range of shear rates and choices of relative cylinder rotations. The observed secondary flows are discussed in terms of destabilizing elastic and centrifugal forces. In the more viscous, more elastic fluid, instabilities are found to be independent of the choice of rotating cylinder and due entirely to elasticity. At the lowest shear rates examined, the first detectable secondary flows are steady counter-rotating vortices forming after a shearing time more than five orders of magnitude greater than the characteristic relaxation time of the fluid. At somewhat higher shear rates, a much more rapidly appearing oscillatory flow is observed to evolve into the steady vortex structure. In the less elastic fluid, the structure first detectable at the lowest shear rates is again steady vortices regardless of the choice of driving cylinder. At all shear rates examined, only elastic stationary vortices are observed in the absence of centrifugal destabilization (outer cylinder rotating). Secondary flows are significantly stronger in the presence of the centrifugal destabilization due to a rotating inner cylinder. Interaction of elasticity and centrifugal forces is found to generate a number of axially translating vortex structures, many of which are described here for the first time. At a shear rate more than five times the critical, another family of instability is observed which closely resembles a purely elastic instability observed by Baumert and Muller (1995). These experimental results are expected to provide a challenging test of numerical simulations of these viscoelastic flows. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.869209
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  • 20
    Electronic Resource
    Electronic Resource
    Origin of a parasitic surface film on p+ type porous silicon (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 6659-6666 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The presence of a parasitic surface film of 80 nm thickness has been observed by x-ray reflectivity on the top of some p+ type porous silicon layers, related to a contamination of the substrate. After testing several methods to clean the substrate and to avoid this film, it was found that a 300 °C thermal annealing of the substrate is sufficient to obtain a homogeneous porous layer. The thickness of the perturbed surface layer is determined by anodic oxidation experiments and the effect of the parasitic surface film on the porous silicon formation is studied by comparing porous layers formed on untreated and on annealed substrates. The hypothesis of a passivation of the boron doping atoms by hydrogen is discussed and we review the observations of nonhomogeneous porous layers which could be related to such a contamination problem. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369041
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