1,809 research outputs found

    I Will Always Love You : As I Do To-Day

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    https://digitalcommons.library.umaine.edu/mmb-vp/3182/thumbnail.jp

    When The Roses Sway

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    https://digitalcommons.library.umaine.edu/mmb-vp/5209/thumbnail.jp

    Years, Years Ago.

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    https://digitalcommons.library.umaine.edu/mmb-vp/5140/thumbnail.jp

    Butterfly Hysteresis and Slow Relaxation of the Magnetization in (Et4N)3Fe2F9: Manifestations of a Single-Molecule Magnet

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    (Et4N)3Fe2F9 exhibits a butterfly--shaped hysteresis below 5 K when the magnetic field is parallel to the threefold axis, in accordance with a very slow magnetization relaxation in the timescale of minutes. This is attributed to an energy barrier Delta=2.40 K resulting from the S=5 dimer ground state of [Fe2F9]^{3-} and a negative axial anisotropy. The relaxation partly occurs via thermally assisted quantum tunneling. These features of a single-molecule magnet are observable at temperatures comparable to the barrier height, due to an extremely inefficient energy exchange between the spin system and the phonons. The butterfly shape of the hysteresis arises from a phonon avalanche effect.Comment: 18 pages, 5 eps figures, latex (elsart

    Mechanisms of decoherence in weakly anisotropic molecular magnets

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    Decoherence mechanisms in crystals of weakly anisotropic magnetic molecules, such as V15, are studied. We show that an important decohering factor is the rapid thermal fluctuation of dipolar interactions between magnetic molecules. A model is proposed to describe the influence of this source of decoherence. Based on the exact solution of this model, we show that at relatively high temperatures, about 0.5 K, the quantum coherence in a V15 molecule is not suppressed, and, in principle, can be detected experimentally. Therefore, these molecules may be suitable prototype systems for study of physical processes taking place in quantum computers.Comment: 4 pages RevTeX, 1 figure (PostScript

    Sequestration of Martian CO2 by mineral carbonation

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    Carbonation is the water-mediated replacement of silicate minerals, such as olivine, by carbonate, and is commonplace in the Earth’s crust. This reaction can remove significant quantities of CO2 from the atmosphere and store it over geological timescales. Here we present the first direct evidence for CO2 sequestration and storage on Mars by mineral carbonation. Electron beam imaging and analysis show that olivine and a plagioclase feldspar-rich mesostasis in the Lafayette meteorite have been replaced by carbonate. The susceptibility of olivine to replacement was enhanced by the presence of smectite veins along which CO2-rich fluids gained access to grain interiors. Lafayette was partially carbonated during the Amazonian, when liquid water was available intermittently and atmospheric CO2 concentrations were close to their present-day values. Earlier in Mars’ history, when the planet had a much thicker atmosphere and an active hydrosphere, carbonation is likely to have been an effective mechanism for sequestration of CO2

    Multiple large shareholders, excess leverage and tunneling: evidence from an emerging market

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Manuscript Type: Empirical Research Question/Issue: Past empirical efforts in corporate governance have examined the effects of large shareholders with the excess control rights on tunneling activities. However, no study has systematically investigated the effects of multiple large shareholders on excess leverage policies and tunneling in an emerging country environment where minority rights protection is weak. In this study, we examine the role of multiple large shareholders and the effects of control contestability of multiple large shareholders on firm excess leverage decision and tunneling by controlling shareholders. Research Findings/Insights: Using a sample of 2,341 Chinese firms for the years 2001 to 2013, we document that the contestability of multiple non-controlling large shareholders relative to controlling shareholders reduces the adoption of excess leverage policies, tunneling and enhances capital investment. Another intriguing finding is that the government as a controlling shareholder exerts significant influence and reduces the monitoring effectiveness of multiple larger shareholders. Theoretical/Academic Implications: By addressing the role of multiple large shareholders on excess leverage decisions, this study makes an important contribution to the corporate governance literature. We extend the recent developments in agency theory regarding the role of multiple large shareholders in constraining expropriation of controlling shareholders with excess control rights and their effect on firm leverage decisions. Our results support the theoretical models which indicate that the presence of multiple large shareholders is an important and efficient internal governance mechanism that mitigates a firm’s agency costs, particularly, in an emerging market environment where corporate governance is weak and inadequate to curb tunneling problem. JEL classification: G15; G34; G3
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