139 research outputs found
The sensitivity to antibiotics of nosocomial strains of acinetobacter baumanii isolated in the tertiary hospitals in the Central Kazakhstan
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
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
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Kinetic theory of plasma adiabatic major radius compression in tokamaks
A kinetic approach is developed to understand the individual charged particle behavior as well as plasma macro parameters (temperature, density, etc.) during the adiabatic R-compression in a tokamak. The perpendicular electric field from Ohm`s law at zero resistivity E = {minus}v{sub E} x B/c is made use of to obtain the equation for particle velocity evolution in order to describe the particle motion during the R-compression. Expressions for both passing and trapped particle energy and pitch angle change are obtained for a plasma with high aspect ratio and circular magnetic surfaces. The particle behavior near the trapped passing boundary during the compression is also studied to understand the shift induced loss of alpha particles produced by D-T fusion reactions in Tokamak Fusion Test Reactor experiments. Qualitative agreement is obtained with the experiments. Solving the drift kinetic equation in the collisional case, i.e., when the collisional frequency {nu}{sub coll} of given species exceeds the inverse compression time {tau}{sub compr}{sup {minus}1}, the authors obtain that the temperature and the density evolution is reduced to the MHD results T {approximately} R{sup {minus}4/3} and n {approximately} R{sup {minus}2}, respectively. In the opposite case, {nu}{sub coll} {much_lt} {tau}{sub compr}{sup {minus}1}, the longitudinal component of the temperature evolve like R(superscript)-2(end superscript) and perpendicular components of the temperature evolve like T{sub {parallel}} {approximately} R{sup {minus}2} and T{sub {perpendicular}} {approximately} R{sup {minus}1}. The effect of toroidicity is negligible in both cases
On elements of the Lax-Phillips scattering scheme for PT-symmetric operators
Generalized PT-symmetric operators acting an a Hilbert space
are defined and investigated. The case of PT-symmetric extensions of a
symmetric operator 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
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
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
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
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
-self-adjoint operators with -symmetries: extension theory approach
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 (-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
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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