227 research outputs found

    Chilled to the Pill: The Japanese Judiciary’s Cool Reception of the Poison Pill and Potential Repercussions

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    While the 1990s is frequently referred to as Japan’s “lost decade” because of the nation’s economic underperformance and weak structures for corporate governance, the past few years have shown a business environment that is in the midst of significant transition. Most importantly, Japan is experiencing a boom in mergers and acquisitions (M&A), with the first half of 2005 alone accounting for an aggregate value of 108.9 billion in Japanese M&A transactions (greater than the 108.5 billion of deal value accumulated in all of 2004). Among the major factors contributing to this trend are the improved cash positions of many companies, a record level of foreign share ownership that has helped strengthen shareholder activism, and, perhaps most significantly, the gradual unwinding of stable cross-shareholding relationships that were previously a staple of Japanese corporate strategy and stability.\u

    Knudsen Diffusion in Silicon Nanochannels

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    Measurements on helium and argon gas flow through an array of parallel, linear channels of 12 nm diameter and 200 micrometer length in a single crystalline silicon membrane reveal a Knudsen diffusion type transport from 10^2 to 10^7 in Knudsen number Kn. The classic scaling prediction for the transport diffusion coefficient on temperature and mass of diffusing species,D_He ~ sqrt(T), is confirmed over a T range from 40 K to 300 K for He and for the ratio of D_He/D_Ar ~ sqrt(m_Ar/m_He). Deviations of the channels from a cylindrical form, resolved with transmission electron microscopy down to subnanometer scales, quantitatively account for a reduced diffusivity as compared to Knudsen diffusion in ideal tubular channels. The membrane permeation experiments are described over 10 orders of magnitude in Kn, encompassing the transition flow regime, by the unified flow model of Beskok and Karniadakis.Comment: 4 pages, 3 figure

    Infrared study of the phonon modes in PrMnO3_3 and CaMnO3_3

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    The infrared (IR) reflectivity spectra of orthorhombic manganese perovskites PrMnO3_3 and CaMnO3_3 are studied in the frequency range of optical phonon modes at temperatures varying from 300 to 4 K. The IR phonon spectra of these two materials are analyzed by a fitting procedure based on a Lorentz model, and assigned to definite vibrational modes of PnmaPnma structures by comparison with the results of lattice dynamical calculations. The calculations have been performed in the framework of a shell model using short range Born-Mayer-Buckingham and long range Coulomb potentials, whose parameters have been optimized in order that the calculated Raman and IR active phonon frequencies, and lattice parameters match with their experimental values. We find a close correspondence between the values of the IR phonon frequencies of PrMnO3_3 and CaMnO3_3, which shows that the substitution of the Pr3+^{3+} ions with Ca2+^{2+} results in a reduction of the frequency of medium- and high-energy IR phonons, and an increase of the frequency of those of low-energy. Nevertheless, the experimentally obtained IR phonon amplitudes of the two materials appear to be unrelated. A comparative study of the vibrational patterns of these modes reveals that most of them correspond to complex atomic vibrations significantly different from PrMnO3_3 to CaMnO3_3 which cannot be assigned only to a given type of vibration (external, bending, or stretching modes). In particular, these results confirm that the structure of CaMnO3_3 is quite far from the ideal (cubic) perovskite structure.Comment: 10 pages, 6 figure

    Observation of charge-density-wave excitations in manganites

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    In the optical conductivity of four different manganites with commensurate charge order (CO), strong peaks appear in the meV range below the ordering temperature T_{CO}. They are similar to those reported for one-dimensional charge density waves (CDW) and are assigned to pinned phasons. The peaks and their overtones allow one to obtain, for La{1-n/8}Ca{n/8}$MnO{3} with n = 5, 6, the electron-phonon coupling, the effective mass of the CO system, and its contribution to the dielectric constant. These results support a description of the CO in La-Ca manganites in terms of moderately weak-coupling and of the CDW theory.Comment: To be published on Phys. Rev. Let

    The E5 protein of the human papillomavirus type 16 down-regulates HLA-I surface expression in calnexin-expressing but not in calnexin-deficient cells

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    The human papillomavirus type 16 E5 protein (HPV16 E5) down-regulates surface expression of HLA-I molecules. The molecular mechanisms underlying this effect are so far unknown. Here we show that HPV16 E5 down-regulates HLA-I surface expression in calnexin-containing but not in calnexin-deficient cells. Immunoprecipitation experiments reveal that calnexin and HPV16E5 can be co-precipitated and that this association depends on the presence of a wild-type first hydrophobic region of E5. When an E5 mutant (M1) in which the first putative transmembrane helix had been disrupted was used for the transfections calnexin-E5 co-precipitation was strongly impaired. In addition, we show that the M1 mutant is only able to marginally down-regulate HLA-I surface expression compared to the wild-type protein. Besides, we demonstrate that E5 forms a ternary complex with calnexin and the heavy chain of HLA-I, which is mediated by the first hydrophobic region of the E5 protein. On the basis of our results we conclude that formation of this complex is responsible for retention of HLA-I molecules in the ER of the cells

    NASA Desert RATS 2010: Preliminary Results for Science Operations Conducted in the San Francisco Volcanic Field, Arizona

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    The National Aeronautics and Space Administration (NASA) is working with international partners to develop the space architectures and mission plans necessary for human spaceflight beyond earth orbit. These mission plans include the exploration of planetary surfaces with significant gravity fields. The Apollo missions to the Moon demonstrated conclusively that surface mobility is a key asset that improves the efficiency of human explorers on a planetary surface. NASA's Desert Research and Technology Studies (Desert RATS) is a multi-year series tests of hardware and operations carried out annually in the high desert of Arizona. Conducted since 1998, these activities are designed to exercise planetary surface hardware and operations in relatively harsh climatic conditions where long-distance, multi-day roving is achievabl

    Probabilistic Plane Fitting in 3D and an Application to Robotic Mapping

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    This paper presents a method for probabilistic plane fitting and an application to robotic 3D mapping. The plane is fitted in an orthogonal least-square sense and the output complies with the conventions of the Symmetries and Perturbation model (SPmodel). In the second part of the paper, the presented plane fitting method is used within a 3D mapping application. It is shown that by using probabilistic information, high precision 3D maps can be generate

    Pseudogap and charge density waves in two dimensions

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    An interaction between electrons and lattice vibrations (phonons) results in two fundamental quantum phenomena in solids: in three dimensions it can turn a metal into a superconductor whereas in one dimension it can turn a metal into an insulator. In two dimensions (2D) both superconductivity and charge-density waves (CDW) are believed to be anomalous. In superconducting cuprates, critical transition temperatures are unusually high and the energy gap may stay unclosed even above these temperatures (pseudogap). In CDW-bearing dichalcogenides the resistivity below the transition can decrease with temperature even faster than in the normal phase and a basic prerequisite for the CDW, the favourable nesting conditions (when some sections of the Fermi surface appear shifted by the same vector), seems to be absent. Notwithstanding the existence of alternatives to conventional theories, both phenomena in 2D still remain the most fascinating puzzles in condensed matter physics. Using the latest developments in high-resolution angle-resolved photoemission spectroscopy (ARPES) here we show that the normal-state pseudogap also exists in one of the most studied 2D examples, dichalcogenide 2H-TaSe2, and the formation of CDW is driven by a conventional nesting instability, which is masked by the pseudogap. Our findings reconcile and explain a number of unusual, as previously believed, experimental responses as well as disprove many alternative theoretical approaches. The magnitude, character and anisotropy of the 2D-CDW pseudogap are intriguingly similar to those seen in superconducting cuprates.Comment: 14 pages including figures and supplementary informatio

    A Compact Approximate Solution to the Friedel-Anderson Impuriy Problem

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    An approximate groundstate of the Anderson-Friedel impurity problem is presented in a very compact form. It requires solely the optimization of two localized electron states and consists of four Slater states (Slater determinants). The resulting singlet ground state energy lies far below the Anderson mean field solution and agrees well with the numerical results by Gunnarsson and Schoenhammer, who used an extensive 1/N_{f}-expansion for a spin 1/2 impurity with double occupancy of the impurity level. PACS: 85.20.Hr, 72.15.R
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