10,229 research outputs found

    Private-public opinion discrepancy

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    In many Western societies there are rising concerns about increasing polarization in public debate. However, statistics on private attitudes paint a different picture: the average attitudes in societies are more moderate and remain rather stable over time. The present paper presents an agent-based model of how such discrepancies between public opinion and private attitudes develop at the scale of micro-societies. Based on social psychological theorizing, the model distinguishes between two types of agents: a) those seeking to gain or maintain a good reputation and status, and b) those seeking to promote group harmony by reaching consensus. We characterized these different types of agents by different decision rules for either voicing their opinion or remaining silent, based on the behavior of their proximal network. Results of the model simulations show that even when the private attitudes of the agents are held constant, publicly expressed opinions can oscillate and (depending on the reputational concerns of individual actors) situations can occur in which minorities as well as majorities are silenced. We conclude that the macro-level consequences of micro-level decisions to either voice an opinion or remain silent provide a foundation for better understanding how public opinions are shaped. Moreover, we discuss the conditions under which public opinion could be considered a good representation of private attitudes in a society

    Soft breaking of Lμ−LτL_\mu-L_\tau symmetry: Light neutrino spectrum and Leptogenesis

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    Continuous U(1)Lμ−LτU(1)_{L_\mu-L_\tau} symmetry can generate quasi degenerate mass spectrum for both left handed light and right handed heavy Majorana neutrinos assuming that the symmetry preserving non zero parameters are nearly same. There is an accidental μτ\mu\tau exchange symmetry in the light and heavy neutrino Majorana mass terms. This implies θ13=0\theta_{13}=0 and θ23=π4\theta_{23}=\frac{\pi}{4}. In addition it generates another zero mixing angle and one zero mass difference. We restrict ourselves to type-I See-Saw mechanism for generation of light neutrino mass. We have found that under U(1)Lμ−LτU(1)_{L_\mu-L_\tau} symmetry cosmological lepton asymmetry vanishes. We break U(1)Lμ−LτU(1)_{L_\mu-L_\tau} such a way that the μτ\mu\tau exchange symmetry preserves in the neutrino sector. We have seen that light neutrino phenomenology can be explained under soft breaking of this symmetry. We have observed that softness of this symmetry breaking depends on the degeneracy of the light neutrino mass spectrum. Quasi-degeneracy of right handed neutrino mass spectrum opens an option for resonant leptogenesis. The degeneracy of the right handed neutrino mass spectrum is restricted through light neutrino data. We observed that for generation of right sized baryon asymmetry common neutrino mass scale m0m_0 have to be of the order of Δmatm2\sqrt{\Delta m^2_{\rm atm}} and corresponding right handed neutrino mass scale have to be nearly 101310^{13} GeV. We also have discussed the effect of RG evolution on light neutrino spectrum and also on baryon asymmetry.Comment: 21 pages, no figure, Revised with the comments on RG effec

    The quadrupole moment of slowly rotating fluid balls

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    In this paper we use the second order formalism of Hartle to study slowly and rigidly rotating stars with focus on the quadrupole moment of the object. The second order field equations for the interior fluid are solved numerically for different classes of possible equations of state and these solutions are then matched to a vacuum solution that includes the general asymptotically flat axisymmetric metric to second order, using the Darmois-Israel procedure. For these solutions we find that the quadrupole moment differs from that of the Kerr metric, as has also been found for some equations of state in other studies. Further we consider the post-Minkowskian limit analytically. In the paper we also illustrate how the relativistic multipole moments can be calculated from a complex gravitational potential.Comment: 13 pages, 5 figure

    From Newton's Laws to the Wheeler-DeWitt Equation

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    This is a pedagogical paper which explains some ideas in cosmology at a level accessible to undergraduate students. It does not use general relativity, but uses the ideas of Newtonian cosmology worked out by Milne and McCrea. The cosmological constant is also introduced within a Newtonian framework. Following standard quantization procedures the Wheeler-DeWitt equation in the minisuperspace approximation is derived for empty and non-empty universes.Comment: 13 pages, 1 figur

    The European Food Safety Authority scientific opinion on a risk profile related to production and consumption of insects as food and feed

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    The increased attention to the use of farmed insects as a novel protein source has raised the question of the safety of insects as human food and as animal feed. This was the background for the European Union (EU) Commission to mandate the European Food Safety Authority (EFSA) to conduct a review of the current knowledge about biological, chemical and environmental risks associated with production and consumption of insects. National authorities in some EU member states (Belgium, the Netherlands and France) have conducted national assessments (ANSES, 2015; FASFC, 2014; NVWA, 2014). However, in the EU, existing regulations constitute legal barriers for marketing insects for human consumption and as protein in animal feed for food producing animals

    Resonant ion-pair formation in electron recombination with HF^+

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    The cross section for resonant ion-pair formation in the collision of low-energy electrons with HF^+ is calculated by the solution of the time-dependent Schrodinger equation with multiple coupled states using a wave packet method. A diabatization procedure is proposed to obtain the electronic couplings between quasidiabatic potentials of ^1Sigma^+ symmetry for HF. By including these couplings between the neutral states, the cross section for ion-pair formation increases with about two orders of magnitude compared with the cross section for direct dissociation. Qualitative agreement with the measured cross section is obtained. The oscillations in the calculated cross section are analyzed. The cross section for ion-pair formation in electron recombination with DF^+ is calculated to determine the effect of isotopic substitution.Comment: 12 pages, 12 figure

    'Designer atoms' for quantum metrology

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    Entanglement is recognized as a key resource for quantum computation and quantum cryptography. For quantum metrology, the use of entangled states has been discussed and demonstrated as a means of improving the signal-to-noise ratio. In addition, entangled states have been used in experiments for efficient quantum state detection and for the measurement of scattering lengths. In quantum information processing, manipulation of individual quantum bits allows for the tailored design of specific states that are insensitive to the detrimental influences of an environment. Such 'decoherence-free subspaces' protect quantum information and yield significantly enhanced coherence times. Here we use a decoherence-free subspace with specifically designed entangled states to demonstrate precision spectroscopy of a pair of trapped Ca+ ions; we obtain the electric quadrupole moment, which is of use for frequency standard applications. We find that entangled states are not only useful for enhancing the signal-to-noise ratio in frequency measurements - a suitably designed pair of atoms also allows clock measurements in the presence of strong technical noise. Our technique makes explicit use of non-locality as an entanglement property and provides an approach for 'designed' quantum metrology

    Observational Evidence of Accretion Disk-Caused Jet Precession in Galactic Nuclei

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    We show that the observational data of extragalactic radio sources tend to support the theoretical relationship between the jet precession period and the optical luminosity of the sources, as predicted by the model in which an accretion disk causes the central black hole to precess.Comment: 13 pages, 1 figure, accepted for publication in ApJ Letter

    Direct observation of the oxygen isotope effect on the in-plane magnetic field penetration depth in optimally doped YBa2_2Cu3_3O7−δ_{7-\delta}

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    We report the first direct observation of the oxygen-isotope (16^{16}O/18^{18}O) effect on the in-plane penetration depth λab\lambda_{ab} in a nearly optimally doped YBa2_2Cu3_3O7−δ_{7-\delta} film using the novel low-energy muon-spin rotation technique. Spin polarized low energy muons are implanted in the film at a known depth zz beneath the surface and precess in the local magnetic field B(z)B(z). This feature allows us to measure directly the profile B(z)B(z) of the magnetic field inside the superconducting film in the Meissner state and to make a model independent determination of λab\lambda_{ab}. A substantial isotope shift Δλab/λab=2.8(7)\Delta\lambda_{ab}/\lambda_{ab}=2.8(7)% at 4 K is observed, implying that the in-plane effective supercarrier mass mab∗m_{ab}^\ast is oxygen-isotope dependent with Δmab∗/mab∗=5.5(1.4)\Delta m_{ab}^\ast/m_{ab}^\ast = 5.5(1.4)%.Comment: 4 pages, 2 figure

    Treatment of hypophosphatemia in the intensive care unit: a review

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    Introduction: Currently no evidence-based guideline exists for the approach to hypophosphatemia in critically ill patients. Methods: We performed a narrative review of the medical literature to identify the incidence, symptoms, and treatment of hypophosphatemia in critically ill patients. Specifically, we searched for answers to the questions whether correction of hypophosphatemia is associated with improved outcome, and whether a certain treatment strategy is superior. Results: Incidence: hypophosphatemia is frequently encountered in the intensive care unit; and critically ill patients are at increased risk for developing hypophosphatemia due to the presence of multiple causal factors. Symptoms: hypophosphatemia may lead to a multitude of symptoms, including cardiac and respiratory failure. Treatment: hypophosphatemia is generally corrected when it is symptomatic or severe. However, although multiple studies confirm the efficacy and safety of intravenous phosphate administration, it remains uncertain when and how to correct hypophosphatemia. Outcome: in some studies, hypophosphatemia was associated with higher mortality; a paucity of randomized controlled evidence exists for whether correction of hypophosphatemia improves the outcome in critically ill patients. Conclusions: Additional studies addressing the current approach to hypophosphatemia in critically ill patients are required. Studies should focus on the association between hypophosphatemia and morbidity and/or mortality, as well as the effect of correction of this electrolyte disorde
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