289 research outputs found

    Predictors of mobilizing online coping versus offline coping resources after negative life events

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    AbstractThis exploratory study drew upon the social compensation/social enhancement hypotheses and weak tie network theory to predict what kind of people supplement offline coping resources with online coping resources more than others. Using a large, representative survey the authors found that low self-esteem, lonely, and socially isolated individuals add more online resources to their mix of preferred coping strategies than their counterparts. These groups benefit from the fact that online coping resources are not as strongly entangled with online social ties as are offline coping resources with offline ties, and from the fact that online coping resources can sometimes be mobilized without any social interactions. In contrast to offline coping, the researchers also found that men mobilize more online coping resources than women. The authors discuss the implications of these findings in terms of the social compensation hypothesis and online weak tie networks

    Multiple sclerosis in a South African-born White man and woman

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    Energies and collapse times of symmetric and symmetry-breaking states of finite systems with a U(1) symmetry

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    We study quantum systems of volume V, which will exhibit the breaking of a U(1) symmetry in the limit of V \to \infty, when V is large but finite. We estimate the energy difference between the `symmetric ground state' (SGS), which is the lowest-energy state that does not breaks the symmetry, and a `pure phase vacuum' (PPV), which approaches a symmetry-breaking vacuum as V \to \infty. Under some natural postulates on the energy of the SGS, it is shown that PPVs always have a higher energy than the SGS, and we derive a lower bound of the excess energy. We argue that the lower bound is O(V^0), which becomes much larger than the excitation energies of low-lying excited states for a large V. We also discuss the collapse time of PPVs for interacting many bosons. It is shown that the wave function collapses in a microscopic time scale, because PPVs are not energy eigenstates. We show, however, that for PPVs the expectation value of any observable, which is a finite polynomial of boson operators and their derivatives, does not collapse for a macroscopic time scale. In this sense, the collapse time of PPVs is macroscopically long.Comment: In the revised manuscript, Eq. (22), Ref. [8], and Notes [13], [15] and [17] have been adde

    Characterizing the recovery of a solid surface after tungsten nano-tendril formation

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    Recovery of a flat tungsten surface from a nano-tendril surface is attempted through three techniques; a mechanical wipe, a 1673&nbsp;K annealing, and laser-induced thermal transients. Results were determined through SEM imaging and elastic recoil detection to assess the helium content in the surface. The mechanical wipe leaves a ∼0.5&nbsp;μm deep layer of nano-tendrils on the surface post-wipe regardless of the initial nano-tendril layer depth. Laser-induced thermal transients only significantly impact the surface morphology at heat loads of 35.2&nbsp;MJ/m2&nbsp;s1/2 or above, however a fully flat or recovered surface was not achieved for 100 transients at this heat load despite reducing the helium content by a factor of ∼7. A 1673&nbsp;K annealing removes all detectable levels of helium but sub-surface voids/bubbles remain intact. The surface is recovered to a nearly flat state with only some remnants of nano-tendrils re-integrating into the surface remaining.</p

    Interference between the halves of a double-well trap containing a Bose-Einstein condensate

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    Interference between the halves of a double-well trap containing a Bose-Einstein condensate is studied. It is found that when the atoms in the two wells are initially in the coherent state, the intensity exhibits collapses and revivals, but it does not for the initial Fock states. Whether the initial states are in the coherent states or in a Fock states, the fidelity time has nothing to do with collision. We point out that interference and its fidelity can be adjusted experimentally by properly preparing the number and initial states of the system.Comment: 10 pages, 3 figures, accepted by Phy. rev.

    Testing Broken U(1) Symmetry in a Two-Component Atomic Bose-Einstein Condensate

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    We present a scheme for determining if the quantum state of a small trapped Bose-Einstein condensate is a state with well defined number of atoms, a Fock state, or a state with a broken U(1) gauge symmetry, a coherent state. The proposal is based on the observation of Ramsey fringes. The population difference observed in a Ramsey fringe experiment will exhibit collapse and revivals due to the mean-field interactions. The collapse and revival times depend on the relative strength of the mean-field interactions for the two components and the initial quantum state of the condensate.Comment: 20 Pages RevTex, 3 Figure

    Solution of generalized fractional reaction-diffusion equations

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    This paper deals with the investigation of a closed form solution of a generalized fractional reaction-diffusion equation. The solution of the proposed problem is developed in a compact form in terms of the H-function by the application of direct and inverse Laplace and Fourier transforms. Fractional order moments and the asymptotic expansion of the solution are also obtained.Comment: LaTeX, 18 pages, corrected typo

    An imperative object calculus

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