21,189 research outputs found

    The letters of Charlotte Mary Yonge (1823-1901) edited by Charlotte Mitchell, Ellen Jordan and Helen Schinske.

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    Charlotte Yonge is one of the most influential and important of Victorian women writers; but study of her work has been handicapped by a tendency to patronise both her and her writing, by the vast number of her publications and by a shortage of information about her professional career. Scholars have had to depend mainly on the work of her first biographer, a loyal disciple, a situation which has long been felt to be unsatisfactory. We hope that this edition of her correspondence will provide for the first time a substantial foundation of facts for the study of her fiction, her historical and educational writing and her journalism, and help to illuminate her biography and also her significance in the cultural and religious history of the Victorian age

    Be-10/Be-7 tracer of atmospheric transport and stratosphere-troposphere exchange

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    The 10Be/7Be ratio is a sensitive tracer of atmospheric transport and stratosphere-troposphere exchange (STE). Data from five NASA aircraft field missions (PEM: West A and B, Tropics A; SONEX; and SUCCESS) have been assembled to produce the largest data set of 10Be,7Be, and their ratio collected to date (\u3e300 samples). Ratios near 0.60 are indicative of tropospheric air with little stratospheric influence, while higher ratios are found in stratospheric air. Samples from the lower stratosphere were all collected within 2.5 km of the tropopause and had ratios \u3e1.27. Of these lower stratosphere samples only 16% had ratios in excess of 3.0, suggesting that higher ratio air resides away from the tropopause. Seasonality observed in the10Be/7Be ratios results from the downwelling of air with elevated ratios from higher in the stratosphere in the spring and summer (midlatitudes) and from the decay of 7Be during descent in the winter polar vortex (high latitudes). Our results illustrate the complexity of STE and some of the mechanisms through which it occurs, including tropopause folding, mixing associated with subtropical jets, and the effect of synoptic systems such as hurricanes and northeasters. The10Be/7Be ratio provides important information beyond that which can be derived from studies that rely on chemical mixing ratios alone

    Uptake of nitrate and sulfate on dust aerosols during TRACE-P

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    Aerosol data collected near Asia on the DC-8 aircraft platform during TRACE-P has been examined for evidence of uptake of NO3− and SO4= on dust surfaces. Data is compared between a sector where dust was predominant and a sector where dust was less of an influence. Coincident with dust were higher mixing ratios of anthropogenic pollutants. HNO3, SO2, and CO were higher in the dust sector than the nondust sector by factors of 2.7, 6.2, and 1.5, respectively. The colocation of dust and pollution sources allowed for the uptake of NO3−and nss-SO4= on the coarse dust aerosols, increasing the mixing ratios of these particulates by factors of 5.7 and 2.6 on average. There was sufficient nss-SO4= to take up all of the NH4+present, with enough excess nss-SO4= to also react with dust CaCO3. This suggests that the enhanced NO3− was not in fine mode NH4NO3. Particulate NO3− (p-NO3−) constituted 54% of the total NO3− (t-NO3−) on average, reaching a maximum of 72% in the dust sector. In the nondust sector, p-NO3− contributed 37% to t-NO3−, likely due to the abundance of sea salts there. In two other sectors where the influence of dust and sea salt were minimal, p-NO3−accounted for \u3c15% of t-NO3−

    Weak Decoherence and Quantum Trajectory Graphs

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    Griffiths' ``quantum trajectories'' formalism is extended to describe weak decoherence. The decoherence conditions are shown to severely limit the complexity of histories composed of fine-grained events.Comment: 12 pages, LaTeX, 3 figures (uses psfig), all in a uuencoded compressed tar fil

    On second-order differential equations with highly oscillatory forcing terms

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    We present a method to compute efficiently solutions of systems of ordinary differential equations that possess highly oscillatory forcing terms. This approach is based on asymptotic expansions in inverse powers of the oscillatory parameter,and features two fundamental advantages with respect to standard ODE solvers: rstly, the construction of the numerical solution is more efficient when the system is highly oscillatory, and secondly, the cost of the computation is essentially independent of the oscillatory parameter. Numerical examples are provided, motivated by problems in electronic engineering

    One qubit almost completely reveals the dynamics of two

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    From the time dependence of states of one of them, the dynamics of two interacting qubits is determined to be one of two possibilities that differ only by a change of signs of parameters in the Hamiltonian. The only exception is a simple particular case where several parameters in the Hamiltonian are zero and one of the remaining nonzero parameters has no effect on the time dependence of states of the one qubit. The mean values that describe the initial state of the other qubit and of the correlations between the two qubits also are generally determined to within a change of signs by the time dependence of states of the one qubit, but with many more exceptions. An example demonstrates all the results. Feedback in the equations of motion that allows time dependence in a subsystem to determine the dynamics of the larger system can occur in both classical and quantum mechanics. The role of quantum mechanics here is just to identify qubits as the simplest objects to consider and specify the form that equations of motion for two interacting qubits can take.Comment: 6 pages with new and updated materia

    Einstein and Jordan frames reconciled: a frame-invariant approach to scalar-tensor cosmology

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    Scalar-Tensor theories of gravity can be formulated in different frames, most notably, the Einstein and the Jordan one. While some debate still persists in the literature on the physical status of the different frames, a frame transformation in Scalar-Tensor theories amounts to a local redefinition of the metric, and then should not affect physical results. We analyze the issue in a cosmological context. In particular, we define all the relevant observables (redshift, distances, cross-sections, ...) in terms of frame-independent quantities. Then, we give a frame-independent formulation of the Boltzmann equation, and outline its use in relevant examples such as particle freeze-out and the evolution of the CMB photon distribution function. Finally, we derive the gravitational equations for the frame-independent quantities at first order in perturbation theory. From a practical point of view, the present approach allows the simultaneous implementation of the good aspects of the two frames in a clear and straightforward way.Comment: 15 pages, matches version to be published on Phys. Rev.

    On the existence of infinitely many closed geodesics on orbifolds of revolution

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    Using the theory of geodesics on surfaces of revolution, we introduce the period function. We use this as our main tool in showing that any two-dimensional orbifold of revolution homeomorphic to S^2 must contain an infinite number of geometrically distinct closed geodesics. Since any such orbifold of revolution can be regarded as a topological two-sphere with metric singularities, we will have extended Bangert's theorem on the existence of infinitely many closed geodesics on any smooth Riemannian two-sphere. In addition, we give an example of a two-sphere cone-manifold of revolution which possesses a single closed geodesic, thus showing that Bangert's result does not hold in the wider class of closed surfaces with cone manifold structures.Comment: 21 pages, 4 figures; for a PDF version see http://www.calpoly.edu/~jborzell/Publications/publications.htm

    Lorentz transformations that entangle spins and entangle momenta

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    Simple examples are presented of Lorentz transformations that entangle the spins and momenta of two particles with positive mass and spin 1/2. They apply to indistinguishable particles, produce maximal entanglement from finite Lorentz transformations of states for finite momenta, and describe entanglement of spins produced together with entanglement of momenta. From the entanglements considered, no sum of entanglements is found to be unchanged.Comment: 5 Pages, 2 Figures, One new paragraph and reference adde
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