351 research outputs found

    What do they know? The effects of outside director acquisition experience on firm acquisition performance

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    This article contributes to the literature on board effectiveness by being perhaps the first to systematically examine how the nature of outside directors' prior experience, and resulting expertise, will influence the performance of a focal firm's strategic initiatives. Our theoretical model is grounded in the psychological literature on expertise and its role in group decision making effectiveness. We focus on outside director expertise in acquisition decision making, and its implications for the performance of the acquisitions of a focal firm. Our conceptual framework indicates that directors will develop expertise in making particular kinds of acquisition decisions (e.g., related or unrelated acquisitions or acquisitions in specific industries or product markets) through their past experiences at other firms with decisions about those specific types of acquisitions, and we predict that this experience and expertise will have positive effects on the performance of a focal firm's acquisitions. We extend our theoretical model to consider the conditions under which relevant director experience will prove most beneficial. Our model predicts that outside director acquisition expertise will deliver the greatest benefits when the focal firm's board is independent from management. We find empirical support for all of our hypotheses. In considering how and when director experience and resulting expertise may influence the performance of corporate acquisitions, our theory and results help to highlight a potential second main focus for research on the long-standing question of what factors render boards of directors effective. Copyright © 2008 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/61235/1/704_ftp.pd

    Characterization of energy trapping in a bulk acoustic wave resonator

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    Acoustic wave fields both within the active electrode area of a solidly mounted 1.8 GHz bulk acoustic waveresonator, and around it in the surrounding region, are measured using a heterodyne laser interferometer. Plate-wave dispersion diagrams for both regions are extracted from the measurement data. The experimental dispersion data reveal the cutoff frequencies of the acoustic vibration modes in the region surrounding the resonator, and, therefore, the energy trapping range of the resonator can readily be determined. The measureddispersionproperties of the surrounding region, together with the abruptly diminishing amplitude of the dispersion curves in the resonator, signal the onset of acoustic leakage from the resonator. This information is important for verifying and further developing the simulation tools used for the design of the resonators. Experimental wave field images, dispersion diagrams for both regions, and the threshold for energy leakage are discussed.Peer reviewe

    Evidence for a Second Order Phase Transition in Glasses at Very Low Temperatures -- A Macroscopic Quantum State of Tunneling Systems

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    Dielectric measurements at very low temperature indicate that in a glass with the eutectic composition BaO-Al2_2O3_3-SiO2_2 a phase transition occurs at 5.84 mK. Below that temperature small magnetic fields of the order of 10 μ\muT cause noticeable changes of the dielectric constant although the glass is insensitive to fields up to 20 T above 10 mK. The experimental findings may be interpreted as the signature of the formation of a new phase in which many tunneling systems perform a coherent motion resulting in a macroscopic wave function.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let

    Extraction of lateral eigenmode properties in thin film bulk acoustic wave resonator from interferometric measurements

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    A heterodyne laser interferometer is used to study acoustic wave fields excited in a 1.8 GHz AlN thin film bulk acoustic waveresonator. The electrical response of the resonator exhibits a strong thickness resonance onto which spurious modes, caused by lateral standing plate waves, are superposed. Optical interferometermeasurements are used to extract dispersion curves of the laterally propagating waves responsible for the spurious responses. A discrete eigenmode spectrum due to the finite lateral dimensions of the resonator is observed. An equivalent circuit model for a multimode resonator is fitted to the mechanical resonator response extracted along a single curve in the dispersion diagram, and is used to determine properties, such as Q-values, of the individual lateral eigenmodes.Measuredwave field images, extracted dispersion curves, and the eigenmode spectrum with the model fitting results are presented.Peer reviewe

    Electron Dephasing in Mesoscopic Metal Wires

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    The low-temperature behavior of the electron phase coherence time, τϕ\tau_{\phi}, in mesoscopic metal wires has been a subject of controversy recently. Whereas theory predicts that τϕ(T)\tau_{\phi}(T) in narrow wires should increase as T2/3T^{-2/3} as the temperature TT is lowered, many samples exhibit a saturation of τϕ\tau_{\phi} below about 1 K. We review here the experiments we have performed recently to address this issue. In particular we emphasize that in sufficiently pure Ag and Au samples we observe no saturation of τϕ\tau_{\phi} down to our base temperature of 40 mK. In addition, the measured magnitude of τϕ\tau_{\phi} is in excellent quantitative agreement with the prediction of the perturbative theory of Altshuler, Aronov and Khmelnitskii. We discuss possible explanations why saturation of τϕ\tau_{\phi} is observed in many other samples measured in our laboratory and elsewhere, and answer the criticisms raised recently by Mohanty and Webb regarding our work.Comment: 14 pages, 3 figures; to appear in proceedings of conference "Fundamental Problems of Mesoscopic Physics", Granada, Spain, 6-11 September, 200

    Ginzburg-Landau-Gor'kov Theory of Magnetic oscillations in a type-II 2-dimensional Superconductor

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    We investigate de Haas-van Alphen (dHvA) oscillations in the mixed state of a type-II two-dimensional superconductor within a self-consistent Gor'kov perturbation scheme. Assuming that the order parameter forms a vortex lattice we can calculate the expansion coefficients exactly to any order. We have tested the results of the perturbation theory to fourth and eight order against an exact numerical solution of the corresponding Bogoliubov-de Gennes equations. The perturbation theory is found to describe the onset of superconductivity well close to the transition point Hc2H_{c2}. Contrary to earlier calculations by other authors we do not find that the perturbative scheme predicts any maximum of the dHvA-oscillations below Hc2H_{c2}. Instead we obtain a substantial damping of the magnetic oscillations in the mixed state as compared to the normal state. We have examined the effect of an oscillatory chemical potential due to particle conservation and the effect of a finite Zeeman splitting. Furthermore we have investigated the recently debated issue of a possibility of a sign change of the fundamental harmonic of the magnetic oscillations. Our theory is compared with experiment and we have found good agreement.Comment: 39 pages, 8 figures. This is a replacement of supr-con/9608004. Several sections changed or added, including a section on the effect of spin and the effect of a conserved number of particles. To be published in Phys. Rev.

    Glass-Like Heat Conduction in High-Mobility Crystalline Semiconductors

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    The thermal conductivity of polycrystalline semiconductors with type-I clathrate hydrate crystal structure is reported. Ge clathrates (doped with Sr and/or Eu) exhibit lattice thermal conductivities typical of amorphous materials. Remarkably, this behavior occurs in spite of the well-defined crystalline structure and relatively high electron mobility (100cm2/Vs\sim 100 cm^2/Vs). The dynamics of dopant ions and their interaction with the polyhedral cages of the structure are a likely source of the strong phonon scattering.Comment: 4 pages, 3 postscript figures, to be published, Phys. Rev. Let

    Anomalous magnetic field dependence of the thermodynamic transition line in the isotropic superconductor (K,Ba)Bi03

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    Thermodynamic (specific heat, reversible magnetization, tunneling spectroscopy) and transport measurements have been performed on high quality (K,Ba)BiO3_3 single crystals. The temperature dependence of the magnetic field HCpH_{Cp} corresponding to the onset of the specific heat anomaly presents a clear positive curvature. HCpH_{Cp} is significantly smaller than the field HΔH_\Delta for which the superconducting gap vanishes but is closely related to the irreversibility line deduced from transport data. Moreover, the temperature dependence of the reversible magnetization present a strong deviation from the Ginzburg--Landau theory emphasazing the peculiar nature of the superconducting transition in this material.Comment: 4 pages, 4 figures, 28 reference
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