2,407 research outputs found

    Learning analytics beyond the LMS: The connected learning analytics toolkit

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    We present a Connected Learning Analytics (CLA) toolkit, which enables data to be extracted from social media and imported into a Learning Record Store (LRS), as defined by the new xAPI standard. A number of implementation issues are discussed, and a mapping that will enable the consistent storage and then analysis of xAPI verb/object/activity statements across different social media and online environments is introduced. A set of example learning activities are proposed, each facilitated by the Learning Analytics beyond the LMS that the toolkit enables

    New limits on cosmic strings from gravitational wave observation

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    We combine new analysis of the stochastic gravitational wave background to be expected from cosmic strings with the latest pulsar timing array (PTA) limits to give an upper bound on the energy scale of the possible cosmic string network, Gμ<1.5×10−11G\mu < 1.5\times 10^{-11} at the 95% confidence level. We also show bounds from LIGO and to be expected from LISA and BBO. Current estimates for the gravitational wave background from supermassive black hole binaries are at the level where a PTA detection is expected. But if PTAs do observe a background soon, it will be difficult in the short term to distinguish black holes from cosmic strings as the source, because the spectral indices from the two sources happen to be quite similar. If PTAs do not observe a background, then the limits on GμG\mu will improve somewhat, but a string network with GμG\mu substantially below 10−1110^{-11} will produce gravitational waves primarily at frequencies too high for PTA observation, so significant further progress will depend on intermediate-frequency observatories such as LISA, DECIGO and BBO.Comment: 9 pages, updated link to companion pape

    Dermatoglyphic Traits of Jewish and Non-Jewish Whites

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    Author Institution: University of Toledo, Toledo 6, Ohi

    Thomas-Fermi Approximation for a Condensate with Higher-order Interactions

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    We consider the ground state of a harmonically trapped Bose-Einstein condensate within the Gross-Pitaevskii theory including the effective-range corrections for a two-body zero-range potential. The resulting non-linear Schr\"odinger equation is solved analytically in the Thomas-Fermi approximation neglecting the kinetic energy term. We present results for the chemical potential and the condensate profiles, discuss boundary conditions, and compare to the usual Thomas-Fermi approach. We discuss several ways to increase the influence of effective-range corrections in experiment with magnetically tunable interactions. The level of tuning required could be inside experimental reach in the near future.Comment: 8 pages, RevTex4 format, 5 figure

    Reconciling threshold and subthreshold expansions for pion-nucleon scattering

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    Heavy-baryon chiral perturbation theory (ChPT) at one loop fails in relating the pion-nucleon amplitude in the physical region and for subthreshold kinematics due to loop effects enhanced by large low-energy constants. Studying the chiral convergence of threshold and subthreshold parameters up to fourth order in the small-scale expansion, we address the question to what extent this tension can be mitigated by including the Δ(1232)\Delta(1232) as an explicit degree of freedom and/or using a covariant formulation of baryon ChPT. We find that the inclusion of the Δ\Delta indeed reduces the low-energy constants to more natural values and thereby improves consistency between threshold and subthreshold kinematics. In addition, even in the Δ\Delta-less theory the resummation of 1/mN1/m_N corrections in the covariant scheme improves the results markedly over the heavy-baryon formulation, in line with previous observations in the single-baryon sector of ChPT that so far have evaded a profound theoretical explanation.Comment: 10 pages, 4 tables, Mathematica notebook with the analytic expressions for threshold and subthreshold parameters included as supplementary material; journal versio

    Neutrino-Nucleus Reactions and Muon Capture in 12C

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    The neutrino-nucleus cross section and the muon capture rate are discussed within a simple formalism which facilitates the nuclear structure calculations. The corresponding formulae only depend on four types of nuclear matrix elements, which are currently used in the nuclear beta decay. We have also considered the non-locality effects arising from the velocity-dependent terms in the hadronic current. We show that for both observables in 12C the higher order relativistic corrections are of the order of ~5 only, and therefore do not play a significant role. As nuclear model framework we use the projected QRPA (PQRPA) and show that the number projection plays a crucial role in removing the degeneracy between the proton-neutron two quasiparticle states at the level of the mean field. Comparison is done with both the experimental data and the previous shell model calculations. Possible consequences of the present study on the determination of the νμ−>νe\nu_\mu ->\nu_e neutrino oscillation probability are briefly addressed.Comment: 29 pages, 6 figures, Revtex4. Several changes were made to the previous manuscript, the results and final conclusions remain unalterable. It has been accepted for publication as a Regular Article in Physical Review

    Detection of gravitational waves from the QCD phase transition with pulsar timing arrays

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    If the cosmological QCD phase transition is strongly first order and lasts sufficiently long, it generates a background of gravitational waves which may be detected via pulsar timing experiments. We estimate the amplitude and the spectral shape of such a background and we discuss its detectability prospects.Comment: 7 pages, 5 figs. Version accepted by PR

    Bracelets of Pride and Guilt? An Experimental Test of Self-Signaling in Charitable Giving

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    Self-signaling theory argues that individuals partly behave prosocially to create or uphold a favorable self-image. To study self-signaling theory, we investigate whether increasing self-image concerns affects charitable giving. In our experiment subjects divide 20 euros between themselves and a charity. Some randomly determined participants are induced to wear a bracelet for the two weeks following their donation decision. This bracelet serves as a private reminder of the experiment, thus making the donation more important for future self-image. If self-signaling plays a role, participants having to wear the bracelet should donate more. We do not find that wearing a bracelet has any effect on donation behavior. This holds although subjects having to wear the bracelet report that at the moment of making the donation, they expect to more often remember the experiment in the following two weeks
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