5,410 research outputs found

    Derivation of Generalized Thomas-Bargmann-Michel-Telegdi Equation for a Particle with Electric Dipole Moment

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    General classical equation of spin motion is explicitly derived for a particle with magnetic and electric dipole moments in electromagnetic fields. Equation describing the spin motion relatively the momentum direction in storage rings is also obtained.Comment: 7 page

    Glass Dynamics at High Strain Rates

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    We present a shear-transformation-zone (STZ) theoretical analysis of molecular-dynamics simulations of a rapidly sheared metallic glass. These simulations are especially revealing because, although they are limited to high strain rates, they span temperatures ranging from well below to well above the glass transition. With one important discrepancy, the STZ theory reproduces the simulation data, including the way in which those data can be made to collapse onto simple curves by a scaling transformation. The STZ analysis implies that the system's behavior at high strain rates is controlled primarily by effective-temperature thermodynamics, as opposed to system-specific details of the molecular interactions. The discrepancy between theory and simulations occurs at the lower strain rates for temperatures near the glass transition. We argue that this discrepancy can be resolved by the same multi-species generalization of STZ theory that has been proposed recently for understanding frequency-dependent viscoelastic responses, Stokes-Einstein violations, and stretched-exponential relaxation in equilibrated glassy materials.Comment: 9 pages, 6 figure

    PD-1 signaling promotes control of chronic viral infection by restricting type-I-interferon-mediated tissue damage

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    Immune responses are essential for pathogen elimination but also cause tissue damage, leading to disease or death. However, it is unclear how the host immune system balances control of infection and protection from the collateral tissue damage. Here, we show that PD-1-mediated restriction of immune responses is essential for durable control of chronic LCMV infection in mice. In contrast to responses in the chronic phase, PD-1 blockade in the subacute phase of infection paradoxically results in viral persistence. This effect is associated with damage to lymphoid architecture and subsequently decreases adaptive immune responses. Moreover, this tissue damage is type I interferon dependent, as sequential blockade of the interferon receptor and PD-1 pathways prevents immunopathology and enhances control of infection. We conclude that PD-1-mediated suppression is required as an immunoregulatory mechanism for sustained responses to chronic viral infection by antagonizing type-I interferon-dependent immunopathology

    Path-integral virial estimator for reaction rate calculation based on the quantum instanton approximation

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    The quantum instanton approximation is a type of quantum transition state theory that calculates the chemical reaction rate using the reactive flux correlation function and its low order derivatives at time zero. Here we present several path-integral estimators for the latter quantities, which characterize the initial decay profile of the flux correlation function. As with the internal energy or heat capacity calculation, different estimators yield different variances (and therefore different convergence properties) in a Monte Carlo calculation. Here we obtain a virial-type estimator by using a coordinate scaling procedure rather than integration by parts, which allows more computational benefits. We also consider two different methods for treating the flux operator, i.e., local-path and global-path approaches, in which the latter achieves a smaller variance at the cost of using second-order potential derivatives. Numerical tests are performed for a one-dimensional Eckart barrier and a model proton transfer reaction in a polar solvent, which illustrates the reduced variance of the virial estimator over the corresponding thermodynamic estimator.Comment: 23 pages, 5 figures, 1 tabl

    Commuting difference operators arising from the elliptic C_2^{(1)}-face model

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    We study a pair of commuting difference operators arising from the elliptic C_2^{(1)}-face model. The operators, whose coefficients are expressed in terms of the Jacobi's elliptic theta function, act on the space of meromorphic functions on the weight space of the C_2 type simple Lie algebra. We show that the space of functions spanned by the level one characters of the affine Lie algebra sp(4,C) is invariant under the action of the difference operators.Comment: latex2e file, 19 pages, no figures; added reference

    Locally embedded presages of global network bursts

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    Spontaneous, synchronous bursting of neural population is a widely observed phenomenon in nervous networks, which is considered important for functions and dysfunctions of the brain. However, how the global synchrony across a large number of neurons emerges from an initially non-bursting network state is not fully understood. In this study, we develop a new state-space reconstruction method combined with high-resolution recordings of cultured neurons. This method extracts deterministic signatures of upcoming global bursts in "local" dynamics of individual neurons during non-bursting periods. We find that local information within a single-cell time series can compare with or even outperform the global mean field activity for predicting future global bursts. Moreover, the inter-cell variability in the burst predictability is found to reflect the network structure realized in the non-bursting periods. These findings demonstrate the deterministic mechanisms underlying the locally concentrated early-warnings of the global state transition in self-organized networks
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