139 research outputs found

    The sensitivity to antibiotics of nosocomial strains of acinetobacter baumanii isolated in the tertiary hospitals in the Central Kazakhstan

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    Del 1972, en l'actual emplaçament des de 1976. D'acer pintat, mesura 5 x 3,54 x 3,20 metres.Calder, Alexander (escultor)Pla general de l'obra. La galeria Maeght va decidir instal·lar una sucursal a Barcelona i va triar fer-ho al carrer de Montcada. Va obrir amb una exposició que incloïa una peça de Calder, Quatre ales. Després fou oferida a l'Ajuntament

    Space of State Vectors in PT Symmetrical Quantum Mechanics

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    Space of states of PT symmetrical quantum mechanics is examined. Requirement that eigenstates with different eigenvalues must be orthogonal leads to the conclusion that eigenfunctions belong to the space with an indefinite metric. The self consistent expressions for the probability amplitude and average value of operator are suggested. Further specification of space of state vectors yield the superselection rule, redefining notion of the superposition principle. The expression for the probability current density, satisfying equation of continuity and vanishing for the bound state, is proposed.Comment: Revised version, explicit expressions for average values and probability amplitude adde

    On elements of the Lax-Phillips scattering scheme for PT-symmetric operators

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    Generalized PT-symmetric operators acting an a Hilbert space H\mathfrak{H} are defined and investigated. The case of PT-symmetric extensions of a symmetric operator SS is investigated in detail. The possible application of the Lax-Phillips scattering methods to the investigation of PT-symmetric operators is illustrated by considering the case of 0-perturbed operators

    Hilbert Space Structures on the Solution Space of Klein-Gordon Type Evolution Equations

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    We use the theory of pseudo-Hermitian operators to address the problem of the construction and classification of positive-definite invariant inner-products on the space of solutions of a Klein-Gordon type evolution equation. This involves dealing with the peculiarities of formulating a unitary quantum dynamics in a Hilbert space with a time-dependent inner product. We apply our general results to obtain possible Hilbert space structures on the solution space of the equation of motion for a classical simple harmonic oscillator, a free Klein-Gordon equation, and the Wheeler-DeWitt equation for the FRW-massive-real-scalar-field models.Comment: 29 pages, slightly revised version, accepted for publication in Class. Quantum Gra

    Impact assessment of the options for surface preparation of glass ionomer cement on the bond strength to the composite material in a series of experiments

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    Laminate technique, or the so-called sandwich technique restoration of posterior group of teeth involves the use of glass ionomer cement and composite material in sequence. The relatively weak mechanical bond between glass ionomer cement and composite at the end of time could lead to the disruption of adhesion. With the advent of new materials, adhesive systems, we believe it is necessary to review the classical technique of the combined use of glass ionomer cement and composite materials. This article is aimed to evaluate the adhesion force between glass ionomer cement and composite material using different adhesive systems and curing techniques.Двухслойная техника, или так называемая сэндвич-техника восстановления боковой группы зубов, предусматривает использование стеклоиономерного цемента и композитного материала в определенной последовательности. Относительно слабая механическая связь между стеклоиономерным цементом и композитом по истечении времени может приводить к нарушению адгезии. С появлением новых материалов, а также адгезивных систем мы считаем необходимым пересмотреть классическую технику комбинированного использования стеклоиономерного цемента и композитных материалов. Данное исследование посвящено оценке силы сцепления между стеклоиономерным цементом и композитным материалом, с использованием различных адгезивных систем и техник полимеризации

    Solvability and PT-symmetry in a double-well model with point interactions

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    We show that and how point interactions offer one of the most suitable guides towards a quantitative analysis of properties of certain specific non-Hermitian (usually called PT-symmetric) quantum-mechanical systems. A double-well model is chosen, an easy solvability of which clarifies the mechanisms of the unavoided level crossing and of the spontaneous PT-symmetry breaking. The latter phenomenon takes place at a certain natural boundary of the domain of the "acceptable" parameters of the model. Within this domain the model mediates a nice and compact explicit illustration of the not entirely standard probabilistic interpretation of the physical bound states in the very recently developed (so called PT symmetric or, in an alternative terminology, pseudo-Hermitian) new, fairly exciting and very quickly developing branch of Quantum Mechanics.Comment: 24 p., written for the special journal issue "Singular Interactions in Quantum Mechanics: Solvable Models". Will be also presented to the int. conference "Pseudo-Hermitian Hamiltonians in Quantum Physics III" (Instanbul, Koc University, June 20 - 22, 2005) http://home.ku.edu.tr/~amostafazadeh/workshop/workshop.ht

    Krein-Space Formulation of PT-Symmetry, CPT-Inner Products, and Pseudo-Hermiticity

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    Emphasizing the physical constraints on the formulation of a quantum theory based on the standard measurement axiom and the Schroedinger equation, we comment on some conceptual issues arising in the formulation of PT-symmetric quantum mechanics. In particular, we elaborate on the requirements of the boundedness of the metric operator and the diagonalizability of the Hamiltonian. We also provide an accessible account of a Krein-space derivation of the CPT-inner product that was widely known to mathematicians since 1950's. We show how this derivation is linked with the pseudo-Hermitian formulation of PT-symmetric quantum mechanics.Comment: published version, 17 page

    JJ-self-adjoint operators with C\mathcal{C}-symmetries: extension theory approach

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    A well known tool in conventional (von Neumann) quantum mechanics is the self-adjoint extension technique for symmetric operators. It is used, e.g., for the construction of Dirac-Hermitian Hamiltonians with point-interaction potentials. Here we reshape this technique to allow for the construction of pseudo-Hermitian (JJ-self-adjoint) Hamiltonians with complex point-interactions. We demonstrate that the resulting Hamiltonians are bijectively related with so called hypermaximal neutral subspaces of the defect Krein space of the symmetric operator. This symmetric operator is allowed to have arbitrary but equal deficiency indices . General properties of the $\cC$ operators for these Hamiltonians are derived. A detailed study of $\cC$-operator parametrizations and Krein type resolvent formulas is provided for $J$-self-adjoint extensions of symmetric operators with deficiency indices . The technique is exemplified on 1D pseudo-Hermitian Schr\"odinger and Dirac Hamiltonians with complex point-interaction potentials

    Statistical Origin of Pseudo-Hermitian Supersymmetry and Pseudo-Hermitian Fermions

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    We show that the metric operator for a pseudo-supersymmetric Hamiltonian that has at least one negative real eigenvalue is necessarily indefinite. We introduce pseudo-Hermitian fermion (phermion) and abnormal phermion algebras and provide a pair of basic realizations of the algebra of N=2 pseudo-supersymmetric quantum mechanics in which pseudo-supersymmetry is identified with either a boson-phermion or a boson-abnormal-phermion exchange symmetry. We further establish the physical equivalence (non-equivalence) of phermions (abnormal phermions) with ordinary fermions, describe the underlying Lie algebras, and study multi-particle systems of abnormal phermions. The latter provides a certain bosonization of multi-fermion systems.Comment: 20 pages, to appear in J.Phys.
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