10,482 research outputs found

    Variational Perturbation Theory for Markov Processes

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    We develop a convergent variational perturbation theory for conditional probability densities of Markov processes. The power of the theory is illustrated by applying it to the diffusion of a particle in an anharmonic potential.Comment: Author Information under http://www.physik.fu-berlin.de/~kleinert/institution.html Latest update of paper also at http://www.physik.fu-berlin.de/~kleinert/33

    Strong-Coupling Calculation of Fluctuation Pressure of a Membrane Between Walls

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    We calculate analytically the proportionality constant in the pressure law of a membrane between parallel walls from the strong-coupling limit of variational perturbation theory up to third order. Extrapolating the zeroth to third approximations to infinity yields the pressure constant alpha=0.0797149. This result lies well within the error bounds of the most accurate available Monte-Carlo result 0.0798 +- 0.0003.Comment: Author Information under http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of paper also at http://www.physik.fu-berlin.de/~kleinert/28

    Generating Functionals for Harmonic Expectation Values of Paths with Fixed End Points. Feynman Diagrams for Nonpolynomial Interactions

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    We introduce a general class of generating functionals for the calculation of quantum-mechanical expectation values of arbitrary functionals of fluctuating paths with fixed end points in configuration or momentum space. The generating functionals are calculated explicitly for harmonic oscillators with time-dependent frequency, and used to derive a smearing formulas for correlation functions of polynomial and nonpolynomials functions of time-dependent positions and momenta. These formulas summarize the effect of thermal and quantum fluctuations, and serve to derive generalized Wick rules and Feynman diagrams for perturbation expansions of nonpolynomial interactions.Comment: Author Information under http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of paper also at http://www.physik.fu-berlin.de/~kleinert/28

    Regulatory and adaptive responses of Lactococcus lactis in situ

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    cum laude graduation (with distinction

    Quantum Monte Carlo Method for Attractive Coulomb Potentials

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    Starting from an exact lower bound on the imaginary-time propagator, we present a Path-Integral Quantum Monte Carlo method that can handle singular attractive potentials. We illustrate the basic ideas of this Quantum Monte Carlo algorithm by simulating the ground state of hydrogen and helium.Comment: 7 pages, 3 table

    IONIZED CALCIUM IN ACIDOSIS: DIFFERENTIAL EFFECT OF HYPERCAPNIC AND LACTIC ACIDOSIS

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    The effects of various forms of acidosis on ionized calcium concentrations were investigated in vivo in rabbits and in vitro in human plasma. Calculation of least square regression equations of ionized calcium (mM) on pH yielded the following regression coefficients in human plasma: hypercapnic acidosis —0.53±0.07; hydrochloric acidosis —0.65±0.06; lactic acidosis —0.27±0.05. These findings in human plasma are roughly paralleled by those in rabbits. From stability constants it was calculated that the formation of Ca-lactate complexes accounts for the difference between lactic and hydrochloric acidosis. It is concluded that differences in the behaviour of ionized calcium between hypercapnic and lactic acidosis might contribute to the known differences in cardiovascular effect

    A dimension conjecture for q-analogues of multiple zeta values

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    We study a class of q-analogues of multiple zeta values given by certain formal q-series with rational coefficients. After introducing a notion of weight and depth for these q-analogues of multiple zeta values we present dimension conjectures for the spaces of their weight- and depth-graded parts, which have a similar shape as the conjectures of Zagier and Broadhurst-Kreimer for multiple zeta values

    Generalized Jacobi-Trudi determinants and evaluations of Schur multiple zeta values

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    We present new determinant expressions for regularized Schur multiple zeta values. These generalize the known Jacobi–Trudi formulas and can be used to quickly evaluate certain types of Schur multiple zeta values. Using these formulas we prove that every Schur multiple zeta value with alternating entries in 1 and 3 can be written as a polynomial in Riemann zeta values. Furthermore, we give conditions on the shape, which determine when such Schur multiple zetas are polynomials purely in odd or in even Riemann zeta values
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