5,177 research outputs found

    Bulk and boundary g2g_2 factorized S-matrices

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    We investigate the g2g_2-invariant bulk (1+1D, factorized) SS-matrix constructed by Ogievetsky, using the bootstrap on the three-point coupling of the vector multiplet to constrain its CDD ambiguity. We then construct the corresponding boundary SS-matrix, demonstrating it to be consistent with Y(g2,a1×a1)Y(g_2,a_1\times a_1) symmetry.Comment: 7 page

    Quantum equilibration in finite time

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    It has recently been shown that small quantum subsystems generically equilibrate, in the sense that they spend most of the time close to a fixed equilibrium state. This relies on just two assumptions: that the state is spread over many different energies, and that the Hamiltonian has non-degenerate energy gaps. Given the same assumptions, it has also been shown that closed systems equilibrate with respect to realistic measurements. We extend these results in two important ways. First, we prove equilibration over a finite (rather than infinite) time-interval, allowing us to bound the equilibration time. Second, we weaken the non degenerate energy gaps condition, showing that equilibration occurs provided that no energy gap is hugely degenerate.Comment: 7 page

    Equilibration of quantum systems and subsystems

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    We unify two recent results concerning equilibration in quantum theory. We first generalise a proof of Reimann [PRL 101,190403 (2008)], that the expectation value of 'realistic' quantum observables will equilibrate under very general conditions, and discuss its implications for the equilibration of quantum systems. We then use this to re-derive an independent result of Linden et. al. [PRE 79, 061103 (2009)], showing that small subsystems generically evolve to an approximately static equilibrium state. Finally, we consider subspaces in which all initial states effectively equilibrate to the same state.Comment: 5 page

    Equilibration of isolated macroscopic quantum systems

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    We investigate the equilibration of an isolated macroscopic quantum system in the sense that deviations from a steady state become unmeasurably small for the overwhelming majority of times within any sufficiently large time interval. The main requirements are that the initial state, possibly far from equilibrium, exhibits a macroscopic population of at most one energy level and that degeneracies of energy eigenvalues and of energy gaps (differences of energy eigenvalues) are not of exceedingly large multiplicities. Our approach closely follows and extends recent works by Short and Farrelly [2012 New J. Phys. 14 013063], in particular going beyond the realm of finite-dimensional systems and large effective dimensions.Comment: 19 page

    On the speed of fluctuations around thermodynamic equilibrium

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    We study the speed of fluctuation of a quantum system around its thermodynamic equilibrium state, and show that the speed will be extremely small for almost all times in typical thermodynamic cases. The setting considered here is that of a quantum system couples to a bath, both jointly described as a closed system. This setting, is the same as the one considered in [N. Linden et al., Phys. Rev. E 79:061103 (2009)] and the ``thermodynamic equilibrium state'' refers to a situation that includes the usual thermodynamic equilibrium case, as well as far more general situations

    Techniques for the realization of ultra- reliable spaceborne computer Final report

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    Bibliography and new techniques for use of error correction and redundancy to improve reliability of spaceborne computer

    Thermodynamic entropy of a many body energy eigenstate

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    It is argued that a typical many body energy eigenstate has a well defined thermodynamic entropy and that individual eigenstates possess thermodynamic characteristics analogous to those of generic isolated systems. We examine large systems with eigenstate energies equivalent to finite temperatures. When quasi-static evolution of a system is adiabatic (in the quantum mechanical sense), two coupled subsystems can transfer heat from one subsystem to another yet remain in an energy eigenstate. To explicitly construct the entropy from the wave function, degrees of freedom are divided into two unequal parts. It is argued that the entanglement entropy between these two subsystems is the thermodynamic entropy per degree of freedom for the smaller subsystem. This is done by tracing over the larger subsystem to obtain a density matrix, and calculating the diagonal and off-diagonal contributions to the entanglement entropy.Comment: 18 page

    An Exploratory Evaluation of a Treatment Mall at a State Psychiatric Hospital

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    The Treatment Mall is a model of inpatient psychosocial treatment provided to adults with severe mental illness to deliver recovery-oriented, evidenced-based treatment and has been implemented in state mental hospitals across the United States. The present study is an exploratory evaluation of a recently implemented Treatment Mall in a state mental hospital. To evaluate this program, the experiences of clients (N=28), staff (N=32), and administrators (N=5) were compiled using a quantitative questionnaire and focused on empowerment, skill development, and satisfaction. Additionally, data from the hospital database (N=183) were extracted and analyzed by comparing frequencies of occurrence 90 days before and 90 days after Treatment Mall implementation. The findings indicate that clients reported learning skills and were satisfied with how they were treated at the Treatment Mall. Female clients and staff viewed independent living and recovery possibilities significantly more positively than male clients and staff. Hospital performance indicators showed no significant changes pre to post implementation.

    No evidence for killer sperm or other selective interactions between human spermatozoa in ejaculates of different males in vitro

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    This study examines one of the possible mechanisms of sperm competition, i.e. the kamikaze sperm hypothesis. This hypothesis states that sperm from different males interact to incapacitate each other in a variety of ways. We used ejaculates from human donors to compare mixes of semen in vitro from the same or different males. We measured the following parameters: (i) the degree of sperm aggregation, velocity and proportion of morphologically normal sperm after 1 and 3 h incubation in undiluted semen samples, (ii) the proportion of viable sperm plus the same parameters as in (i) in 'swim-up' sperm suspensions after 1 and 3 h incubation, (iii) the degree of self and non-self sperm aggregation using fluorescent dyes to distinguish the sperm of different males, and (iv) the extent of sperm capacitation and acrosome-reacted sperm in mixtures of sperm from the same and different males. We observed very few significant changes in sperm aggregation or performance in mixtures of sperm from different males compared with mixtures from the same male and none that were consistent with previously reported findings. The incapacitation of rival sperm therefore seems an unlikely mechanism of sperm competition in humans
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