556 research outputs found

    Noncommutative Dynamics of Random Operators

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    We continue our program of unifying general relativity and quantum mechanics in terms of a noncommutative algebra A{\cal A} on a transformation groupoid Γ=E×G\Gamma = E \times G where EE is the total space of a principal fibre bundle over spacetime, and GG a suitable group acting on Γ\Gamma . We show that every a∈Aa \in {\cal A} defines a random operator, and we study the dynamics of such operators. In the noncommutative regime, there is no usual time but, on the strength of the Tomita-Takesaki theorem, there exists a one-parameter group of automorphisms of the algebra A{\cal A} which can be used to define a state dependent dynamics; i.e., the pair (A,ϕ)({\cal A}, \phi), where ϕ\phi is a state on A{\cal A}, is a ``dynamic object''. Only if certain additional conditions are satisfied, the Connes-Nikodym-Radon theorem can be applied and the dependence on ϕ\phi disappears. In these cases, the usual unitary quantum mechanical evolution is recovered. We also notice that the same pair (A,ϕ)({\cal A}, \phi) defines the so-called free probability calculus, as developed by Voiculescu and others, with the state ϕ\phi playing the role of the noncommutative probability measure. This shows that in the noncommutative regime dynamics and probability are unified. This also explains probabilistic properties of the usual quantum mechanics.Comment: 13 pages, LaTe

    Diagonalizing operators over continuous fields of C*-algebras

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    It is well known that in the commutative case, i.e. for A=C(X)A=C(X) being a commutative C*-algebra, compact selfadjoint operators acting on the Hilbert C*-module HAH_A (= continuous families of such operators K(x)K(x), x∈Xx\in X) can be diagonalized if we pass to a bigger W*-algebra L∞(X)=A⊃AL^\infty(X)={\bf A} \supset A which can be obtained from AA by completing it with respect to the weak topology. Unlike the "eigenvectors", which have coordinates from A\bf A, the "eigenvalues" are continuous, i.e. lie in the C*-algebra AA. We discuss here the non-commutative analog of this well-known fact. Here the "eigenvalues" are defined not uniquely but in some cases they can also be taken from the initial C*-algebra instead of the bigger W*-algebra. We prove here that such is the case for some continuous fields of real rank zero C*-algebras over a one-dimensional manifold and give an example of a C*-algebra AA for which the "eigenvalues" cannot be chosen from AA, i.e. are discontinuous. The main point of the proof is connected with a problem on almost commuting operators. We prove that for some C*-algebras if h∈Ah\in A is a selfadjoint, u∈Au\in A is a unitary and if the norm of their commutant [u,h][u,h] is small enough then one can connect uu with the unity by a path u(t)u(t) so that the norm of [u(t),h][u(t),h] would be also small along this path.Comment: 21 pages, LaTeX 2.09, no figure

    Electrophoretic Analysis of Indian Isolates of Mycoplasma agalactiae

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    Mycoplasma agalactiae and Mycoplasma bovis both are responsible for respiratory conditions in sheep and goats. M. agalactiae is a major pathogen of sheep and goats and accounts for almost 90% of outbreaks of contagious agalactia syndrome in goats and almost 100% in sheep. On the basis of clinical signs and cultural, morphological, and biochemical characterization it is almost impossible to differentiate between both the species. Moreover, due to presence of genomic and proteomic similarity most of the time routine diagnostic tests fail to differentiate between them. Hence the present study was conducted to find out the protein profile of isolates of both the species by SDS-PAGE and to find out the cross-reacting as well as differentiating immunogenic proteins by Immunoblotting, which can be of immunoprophylactic as well as diagnostic values. The study revealed 6-7 major immunogenic cross-reactive proteins with the presence of two important non-cross-reacting species specific polypeptides particularly 25.50 and 24.54 kDa in M. agalactiae and M. bovis, respectively, that might be of diagnostic values

    Finite difference lattice Boltzmann model with flux limiters for liquid-vapor systems

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    In this paper we apply a finite difference lattice Boltzmann model to study the phase separation in a two-dimensional liquid-vapor system. Spurious numerical effects in macroscopic equations are discussed and an appropriate numerical scheme involving flux limiter techniques is proposed to minimize them and guarantee a better numerical stability at very low viscosity. The phase separation kinetics is investigated and we find evidence of two different growth regimes depending on the value of the fluid viscosity as well as on the liquid-vapor ratio.Comment: 10 pages, 10 figures, to be published in Phys. Rev.

    The Bond-Algebraic Approach to Dualities

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    An algebraic theory of dualities is developed based on the notion of bond algebras. It deals with classical and quantum dualities in a unified fashion explaining the precise connection between quantum dualities and the low temperature (strong-coupling)/high temperature (weak-coupling) dualities of classical statistical mechanics (or (Euclidean) path integrals). Its range of applications includes discrete lattice, continuum field, and gauge theories. Dualities are revealed to be local, structure-preserving mappings between model-specific bond algebras that can be implemented as unitary transformations, or partial isometries if gauge symmetries are involved. This characterization permits to search systematically for dualities and self-dualities in quantum models of arbitrary system size, dimensionality and complexity, and any classical model admitting a transfer matrix representation. Dualities like exact dimensional reduction, emergent, and gauge-reducing dualities that solve gauge constraints can be easily understood in terms of mappings of bond algebras. As a new example, we show that the (\mathbb{Z}_2) Higgs model is dual to the extended toric code model {\it in any number of dimensions}. Non-local dual variables and Jordan-Wigner dictionaries are derived from the local mappings of bond algebras. Our bond-algebraic approach goes beyond the standard approach to classical dualities, and could help resolve the long standing problem of obtaining duality transformations for lattice non-Abelian models. As an illustration, we present new dualities in any spatial dimension for the quantum Heisenberg model. Finally, we discuss various applications including location of phase boundaries, spectral behavior and, notably, we show how bond-algebraic dualities help constrain and realize fermionization in an arbitrary number of spatial dimensions.Comment: 131 pages, 22 figures. Submitted to Advances in Physics. Second version including a new section on the eight-vertex model and the correction of several typo

    Quality indicators in a mycobacteriology laboratory supporting clinical trials for pulmonary tuberculosis

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    AbstractBackgroundDocumentation of structured quality indicators for mycobacteriology laboratories supporting exclusively controlled clinical trials in pulmonary tuberculosis (PTB) is lacking.ObjectiveTo document laboratory indicators for a solid (Lowenstein–Jensen medium) culture system in a mycobacteriology laboratory for a period of 4years (2007–2010).MethodsThe sputum samples, collected from PTB suspects/patients enrolled in clinical trials, were subjected to fluorescence microscopy, culture and drug sensitivity testing (DST). Data was retrospectively collected from TB laboratory registers and computed using pre-formulated Microsoft Office Excel. Laboratory indicators were calculated and analyzed.ResultsThe number of samples processed in a calendar year varied from 6261 to 10,710. Of the samples processed in a calendar year, specimen contamination (4.8–6.9%), culture positives (78.4–85.1%) among smear positives, smear positives (71.8–79.0%) among culture positive samples, smear negatives among culture negative samples (95.2–96.7%), and average time to report DST results (76–97days) varied as shown in parentheses.ConclusionValues of quality indicators in mycobacteriology laboratories supporting exclusively clinical trials of PTB have to be defined and used for meaningful monitoring of laboratories

    Dendritic Core-Shell Macromolecules Soluble in Supercritical Carbon Dioxide

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    International audienceSupercritical carbon dioxide has found strong interest as a reaction medium recently.1,2 As an alternative to organic solvents, compressed carbon dioxide is toxicologically harmless, nonflammable, inexpensive, and environmentally benign.3 Its accessible critical temperature and pressure (Tc ) 31 °C, Pc ) 7.38 MPa, Fc ) 0.468 g cm-3)4 and the possibility of tuning the solvent-specific properties between the ones of liquid and gas are very attractive
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