354 research outputs found

    Three-dimensional bulk band dispersion in polar BiTeI with giant Rashba-type spin splitting

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    In layered polar semiconductor BiTeI, giant Rashba-type spin-split band dispersions show up due to the crystal structure asymmetry and the strong spin-orbit interaction. Here we investigate the 3-dimensional (3D) bulk band structures of BiTeI using the bulk-sensitive hνh\nu-dependent soft x-ray angle resolved photoemission spectroscopy (SX-ARPES). The obtained band structure is shown to be well reproducible by the first-principles calculations, with huge spin splittings of 300{\sim}300 meV at the conduction-band-minimum and valence-band-maximum located in the kz=π/ck_z=\pi/c plane. It provides the first direct experimental evidence of the 3D Rashba-type spin splitting in a bulk compound.Comment: 9 pages, 4 figure

    Sequent Calculus in the Topos of Trees

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    Nakano's "later" modality, inspired by G\"{o}del-L\"{o}b provability logic, has been applied in type systems and program logics to capture guarded recursion. Birkedal et al modelled this modality via the internal logic of the topos of trees. We show that the semantics of the propositional fragment of this logic can be given by linear converse-well-founded intuitionistic Kripke frames, so this logic is a marriage of the intuitionistic modal logic KM and the intermediate logic LC. We therefore call this logic KMlin\mathrm{KM}_{\mathrm{lin}}. We give a sound and cut-free complete sequent calculus for KMlin\mathrm{KM}_{\mathrm{lin}} via a strategy that decomposes implication into its static and irreflexive components. Our calculus provides deterministic and terminating backward proof-search, yields decidability of the logic and the coNP-completeness of its validity problem. Our calculus and decision procedure can be restricted to drop linearity and hence capture KM.Comment: Extended version, with full proof details, of a paper accepted to FoSSaCS 2015 (this version edited to fix some minor typos

    Field-induced segregation of ferromagnetic nano-domains in Pr0.5_{0.5}Sr0.5_{0.5}MnO3_3, detected by 55^{55}Mn NMR

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    The antiferromagnetic manganite Pr0.5_{0.5}Sr0.5_{0.5}MnO3_3 was investigated at low temperature by means of magnetometry and 55^{55}Mn NMR. A field-induced transition to a ferromagnetic state is detected by magnetization measurements at a threshold field of a few tesla. NMR shows that the ferromagnetic phase develops from zero field by the nucleation of microscopic ferromagnetic domains, consisting of an inhomogeneous mixture of tilted and fully aligned parts. At the threshold the NMR spectrum changes discontinuously into that of a homogeneous, fully aligned, ferromagnetic state, suggesting a percolative origin for the ferromagnetic transition.Comment: Latex 2.09 language. 4 pages, 3 figures, 23 references. Submitted to physical Review

    Consequences of Kaizen Practices in MSMEs in the Philippines: The Case of the Manufacturing Productivity Extension Program (MPEX)

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    The Manufacturing Productivity Extension Program (MPEX) is a fully subsidized public-instigated productivity improvement program directed toward the micro, small, and medium enterprise (MSME) sector. While not advertised and packaged as a Kaizen initiative, it has all the elements of the Kaizen philosophy. Based on survey responses from 64 MPEX beneficiaries and 47 non-MPEX beneficiaries, the study showed that MPEX increased the number of product lines implying that Kaizen practice leads to product innovation among firms. Due to data and confounding issues, significant difference in productivity in terms of number of workers and sales per worker was not established. Firm asset size was implied to influence the capability to implement Kaizen. Regulatory compliance and customer demand requirements and entrepreneurial capacity are catalysts for enabling, adopting, and sustaining Kaizen implementation
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