3,739 research outputs found

    Zeno Dynamics of von Neumann Algebras

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    The dynamical quantum Zeno effect is studied in the context of von Neumann algebras. We identify a localized subalgebra on which the Zeno dynamics acts by automorphisms. The Zeno dynamics coincides with the modular dynamics of that subalgebra, if an additional assumption is satisfied. This relates the modular operator of that subalgebra to the modular operator of the original algebra by a variant of the Kato-Lie-Trotter product formula.Comment: Revised version; further typos corrected; 9 pages, AMSLaTe

    Electric dipole rovibrational transitions in HD molecule

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    The rovibrational electric dipole transitions in the ground electronic state of the HD molecule are studied. A simple, yet rigorous formula is derived for the transition rates in terms of the electric dipole moment function D(R)D(R), which is calculated in a wide range of RR. Our numerical results for transition rates are in moderate agreement with experiments and previous calculations, but are at least an order of magnitude more accurate.Comment: 7 pages, 1 figur

    Classical simulation of noninteracting-fermion quantum circuits

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    We show that a class of quantum computations that was recently shown to be efficiently simulatable on a classical computer by Valiant corresponds to a physical model of noninteracting fermions in one dimension. We give an alternative proof of his result using the language of fermions and extend the result to noninteracting fermions with arbitrary pairwise interactions, where gates can be conditioned on outcomes of complete von Neumann measurements in the computational basis on other fermionic modes in the circuit. This last result is in remarkable contrast with the case of noninteracting bosons where universal quantum computation can be achieved by allowing gates to be conditioned on classical bits (quant-ph/0006088).Comment: 26 pages, 1 figure, uses wick.sty; references added to recent results by E. Knil

    Improvement in efficiency of the electrocatalytic reduction of hydrogen peroxide by prussian blue produced from the [Fe(CN)5(mpz)]2– complex

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    Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Hydrogen peroxide is one of the most important molecules in chemical signaling in living organisms. Because of this, its sensing is indispensable for the diagnosis of many diseases. Among the materials used for the detection and quantification of H2O2, Prussian Blue (PB) has been highlighted due to its performance. Therefore, the search for alternatives or the improvement of PB performance is a challenge. In this context, our motivation was to evaluate how the ligand N-methylpyrazinium affects the structure and reactivity of Prussian Blue films produced from [Fe(CN)(5)(mpz)](2-) (PB-mpz). Based on the results, it was possible to conclude that the ligand is coordinated to the complex inside the PB framework and consequently contributes to the generation of a noncrystalline structure. The ions contained in buffer solutions can react with Prussian Blue by binding to Fe3+ and breaking the structure. In addition, a PB-mpz film in HCl/KCl showed higher sensitivity towards H2O2 than a PB film.Hydrogen peroxide is one of the most important molecules in chemical signaling in living organisms. Because of this, its sensing is indispensable for the diagnosis of many diseases. Among the materials used for the detection and quantification of H2O2, Pr20171319791988CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)459923/2014‐52013/22127‐2sem informaçãoThe authors acknowledge the financial support of the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (grant no. 459923/2014‐5), the Fundo de Apoio ao Ensino, à Pesquisa e à Extensão – Universidade Estadual de Campinas (FAEPEX‐UNICAMP

    Spectral Properties of delta-Plutonium: Sensitivity to 5f Occupancy

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    By combining the local density approximation (LDA) with dynamical mean field theory (DMFT), we report a systematic analysis of the spectral properties of ÎŽ\delta-plutonium with varying 5f5f occupancy. The LDA Hamiltonian is extracted from a tight-binding (TB) fit to full-potential linearized augmented plane-wave (FP-LAPW) calculations. The DMFT equations are solved by the exact quantum Monte Carlo (QMC) method and the Hubbard-I approximation. We have shown for the first time the strong sensitivity of the spectral properties to the 5f5f occupancy, which suggests using this occupancy as a fitting parameter in addition to the Hubbard UU. By comparing with PES data, we conclude that the ``open shell'' 5f55f^{5} configuration gives the best agreement, resolving the controversy over 5f5f ``open shell'' versus ``close shell'' atomic configurations in ÎŽ\delta-Pu.Comment: 6 pages, 2 embedded color figures, to appear in Physical Review

    Relativistic calculation of the triton binding energy and its implications

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    First results for the triton binding energy obtained from the relativistic spectator or Gross equation are reported. The Dirac structure of the nucleons is taken into account. Numerical results are presented for a family of realistic OBE models with off-shell scalar couplings. It is shown that these off-shell couplings improve both the fits to the two-body data and the predictions for the binding energy.Comment: 5 pages, RevTeX 3.0, 1 figure (uses epsfig.sty

    The Gas2 family protein Pigs is a microtubule +TIP that affects cytoskeleton organisation

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    ABSTRACTCoordination between different cytoskeletal systems is crucial for many cell biological functions, including cell migration and mitosis, and also plays an important role during tissue morphogenesis. Proteins of the class of cytoskeletal crosslinkers, or cytolinkers, have the ability to interact with more than one cytoskeletal system at a time and are prime candidates to mediate any coordination. One such class comprises the Gas2-like proteins, combining a conserved calponin-homology-type actin-binding domain and a Gas2 domain predicted to bind microtubules (MTs). This domain combination is also found in spectraplakins, huge cytolinkers that play important roles in many tissues in both invertebrates and vertebrates. Here, we dissect the ability of the single Drosophila Gas2-like protein Pigs to interact with both actin and MT cytoskeletons, both in vitro and in vivo, and illustrate complex regulatory interactions that determine the localisation of Pigs to and its effects on the cytoskeleton.Summary: Detailed analysis of the ability of the Drosophila cytolinker protein Pigs to modulate its cytoskeleton-interacting functions (+TIP tracking, microtubule shaft binding, actin binding and actin–microtubule crosslinking)

    Non-Abelian Monopole and Dyon Solutions in a Modified Einstein-Yang-Mills-Higgs System

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    We have studied a modified Yang-Mills-Higgs system coupled to Einstein gravity. The modification of the Einstein-Hilbert action involves a direct coupling of the Higgs field to the scalar curvature. In this modified system we are able to write a Bogomol'nyi type condition in curved space and demonstrate that the positive static energy functional is bounded from below. We then investigate non-Abelian sperically symmetric static solutions in a similar fashion to the `t Hooft-Polyakov monopole. After reviewing previously studied monopole solutions of this type, we extend the formalism to included electric charge and we present dyon solutions.Comment: 18 pages LaTeX, 7 eps-figure

    Release of copper-amended particles from micronized copper-pressure-treated wood during mechanical abrasion

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    Background: We investigated the particles released due to abrasion of wood surfaces pressure-treated with micronized copper azole (MCA) wood preservative and we gathered preliminary data on its in vitro cytotoxicity for lung cells. The data were compared with particles released after abrasion of untreated, water (0% MCA)-pressure-treated, chromated copper (CC)-pressure-treated wood, and varnished wood. Size, morphology, and composition of the released particles were analyzed. Results: Our results indicate that the abrasion of MCA-pressure-treated wood does not cause an additional release of nanoparticles from the unreacted copper (Cu) carbonate nanoparticles from of the MCA formulation. However, a small amount of released Cu was detected in the nanosized fraction of wood dust, which could penetrate the deep lungs. The acute cytotoxicity studies were performed on a human lung epithelial cell line and human macrophages derived from a monocytic cell line. These cell types are likely to encounter the released wood particles after inhalation. Conclusions: Our findings indicate that under the experimental conditions chosen, MCA does not pose a specific additional nano-risk, i.e. there is no additional release of nanoparticles and no specific nano-toxicity for lung epithelial cells and macrophages
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