296 research outputs found

    Social Influence, Risk and Benefit Perceptions, and the Acceptability of Risky Energy Technologies:An Explanatory Model of Nuclear Power Versus Shale Gas

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    Risky energy technologies are often controversial and debates around them are polarized; in such debates public acceptability is key. Research on public acceptability has emphasized the importance of intrapersonal factors but has largely neglected the influence of interpersonal factors. In an online survey (N = 948) with a representative sample of the United Kingdom, we therefore integrate interpersonal factors (i.e., social influence as measured by social networks) with two risky energy technologies that differ in familiarity (nuclear power vs. shale gas) to examine how these factors explain risk and benefit perceptions and public acceptability. Findings show that benefit perceptions are key in explaining acceptability judgments. However, risk perceptions are more important when people are less familiar with the energy technology. Social network factors affect perceived risks and benefits associated with risky energy technology, hereby indirectly helping to form one's acceptability judgment toward the technology. This effect seems to be present regardless of the perceived familiarity with the energy technology. By integrating interpersonal with intrapersonal factors in an explanatory model, we show how the current "risk-benefit acceptability" model used in risk research can be further developed to advance the current understanding of acceptability formation

    Carrier-envelope phase control over pathway interference in strong-field dissociation of H2+_2^+

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    The dissociation of an H2+_2^+ molecular-ion beam by linearly polarized, carrier-envelope-phase-tagged 5 fs pulses at 4×1014\times10^{14} W/cm2^2 with a central wavelength of 730 nm was studied using a coincidence 3D momentum imaging technique. Carrier-envelope-phase-dependent asymmetries in the emission direction of H+^+ fragments relative to the laser polarization were observed. These asymmetries are caused by interference of odd and even photon number pathways, where net-zero photon and 1-photon interference predominantly contributes at H+^++H kinetic energy releases of 0.2 -- 0.45 eV, and net-2-photon and 1-photon interference contributes at 1.65 -- 1.9 eV. These measurements of the benchmark H2+_2^+ molecule offer the distinct advantage that they can be quantitatively compared with \textit{ab initio} theory to confirm our understanding of strong-field coherent control via the carrier-envelope phase

    A computational framework for polyconvex large strain elasticity for geometrically exact beam theory

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    In this paper, a new computational framework is presented for the analysis of nonlinear beam finite elements subjected to large strains. Specifically, the methodology recently introduced in Bonet et al. (Comput Methods Appl Mech Eng 283:1061–1094, 2015) in the context of three dimensional polyconvex elasticity is extended to the geometrically exact beam model of Simo (Comput Methods Appl Mech Eng 49:55–70, 1985), the starting point of so many other finite element beam type formulations. This new variational framework can be viewed as a continuum degenerate formulation which, moreover, is enhanced by three key novelties. First, in order to facilitate the implementation of the sophisticated polyconvex constitutive laws particularly associated with beams undergoing large strains, a novel tensor cross product algebra by Bonet et al. (Comput Methods Appl Mech Eng 283:1061–1094, 2015) is adopted, leading to an elegant and physically meaningful representation of an otherwise complex computational framework. Second, the paper shows how the novel algebra facilitates the re-expression of any invariant of the deformation gradient, its cofactor and its determinant in terms of the classical beam strain measures. The latter being very useful whenever a classical beam implementation is preferred. This is particularised for the case of a Mooney–Rivlin model although the technique can be straightforwardly generalised to other more complex isotropic and anisotropic polyconvex models. Third, the connection between the two most accepted restrictions for the definition of constitutive models in three dimensional elasticity and beams is shown, bridging the gap between the continuum and its degenerate beam description. This is carried out via a novel insightful representation of the tangent operator

    Observation of strong final-state effects in pi+ production in pp collisions at 400 MeV

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    Differential cross sections of the reactions ppdπ+pp \to d\pi^+ and pppnπ+pp \to pn\pi^+ have been measured at Tp=400T_p = 400 MeV by detecting the charged ejectiles in the angular range 40ΘLab214^0 \leq \Theta_{Lab} \leq 21^\circ. The deduced total cross sections agree well with those published previously for neighbouring energies. The invariant mass spectra are observed to be strongly affected by Δ\Delta production and NNNN final-state interaction. The data are well described by Monte Carlo simulations including both these effects. The ratio of pppnπ+pp \to pn\pi^+ and ppdπ+pp \to d\pi^+ cross sections also compares favourably to a recent theoretical prediction which suggests a dominance of npnp-production in the relative 3S1^3S_1-state.Comment: 17 pages, 5 figure

    Detailed comparison of the pp -> \pi^+pn and pp -> \pi^+d reactions at 951 MeV

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    The positively charged pions produced in proton-proton collisions at a beam momentum of 1640 MeV/c were measured in the forward direction with a high resolution magnetic spectrograph. The missing mass distribution shows the bound state (deuteron) clearly separated from the pnpn continuum. Despite the very good resolution, there is no evidence for any significant production of the pnpn system in the spin-singlet state. However, the σ(ppπ+pn)/σ(ppπ+d)\sigma(pp\to \pi^+pn)/\sigma(pp\to \pi^+d) cross section ratio is about twice as large as that predicted from SS-wave final-state-interaction theory and it is suggested that this is due to DD-state effects in the pnpn system.Comment: 8 pages, 3 figure

    The importance of Rydberg orbitals in dissociative ionization of small hydrocarbon molecules in intense laser fields

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    Much of our intuition about strong-field processes is built upon studies of diatomic molecules, which typically have electronic states that are relatively well separated in energy. In polyatomic molecules, however, the electronic states are closer together, leading to more complex interactions. A combined experimental and theoretical investigation of strong-field ionization followed by hydrogen elimination in the hydrocarbon series C2D2, C2D4 and C2D6 reveals that the photofragment angular distributions can only be understood when the field-dressed orbitals rather than the field-free orbitals are considered. Our measured angular distributions and intensity dependence show that these field-dressed orbitals can have strong Rydberg character for certain orientations of the molecule relative to the laser polarization and that they may contribute significantly to the hydrogen elimination dissociative ionization yield. These findings suggest that Rydberg contributions to field-dressed orbitals should be routinely considered when studying polyatomic molecules in intense laser fields

    Subfemtosecond steering of hydrocarbon deprotonation through superposition of vibrational modes

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    Subfemtosecond control of the breaking and making of chemical bonds in polyatomic molecules is poised to open new pathways for the laser-driven synthesis of chemical products. The break-up of the C-H bond in hydrocarbons is an ubiquitous process during laser-induced dissociation. While the yield of the deprotonation of hydrocarbons has been successfully manipulated in recent studies, full control of the reaction would also require a directional control (that is, which C-H bond is broken). Here, we demonstrate steering of deprotonation from symmetric acetylene molecules on subfemtosecond timescales before the break-up of the molecular dication. On the basis of quantum mechanical calculations, the experimental results are interpreted in terms of a novel subfemtosecond control mechanism involving non-resonant excitation and superposition of vibrational degrees of freedom. This mechanism permits control over the directionality of chemical reactions via vibrational excitation on timescales defined by the subcycle evolution of the laser waveform

    Multielectron effects in strong-field dissociative ionization of molecules

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    We study triple-ionization-induced, spatially asymmetric dissociation of N[subscript 2] using angular streaking in an elliptically polarized laser pulse in conjunction with few-cycle pump-probe experiments. The kinetic-energy-release dependent directional asymmetry in the ion sum-momentum distribution reflects the internuclear distance dependence of the fragmentation mechanism. Our results show that for 5–35-fs near-infrared laser pulses with intensities reaching 10[superscript 15] W/cm², charge exchange between nuclei plays a minor role in the triple ionization of N[subscript 2]. We demonstrate that angular streaking provides a powerful tool for probing multielectron effects in strong-field dissociative ionization of small molecules

    Fragmentation of CD+ induced by intense ultrashort laser pulses

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    Citation: Graham, L., Zohrabi, M., Gaire, B., Ablikim, U., Jochim, B., Berry, B., . . . Ben-Itzhak, I. (2015). Fragmentation of CD+ induced by intense ultrashort laser pulses. Physical Review A, 91(2), 11. doi:10.1103/PhysRevA.91.023414The fragmentation of CD[superscript +] in intense ultrashort laser pulses was investigated using a coincidence three-dimensional momentum imaging technique improved by employing both transverse and longitudinal electric fields. This allowed clear separation of all fragmentation channels and the determination of the kinetic energy release down to nearly zero, for a molecule with significant mass asymmetry. The most probable dissociation pathways for the two lowest dissociation limits, C[superscript +]+D and C+D[superscript +], were identified for both 22-fs, 798-nm and 50-fs, 392-nm pulses. Curiously, the charge asymmetric dissociation of CD[superscript 2+] was not observed for 392-nm photons, even though it was clearly visible for the fundamental 798 nm at the same peak intensity

    The role of intuition in entrepreneurship and business venturing decisions

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    Entrepreneurial intuition is the affectively charged recognition and evaluation of a business venturing opportunity arising as a result of involuntary, rapid, non-conscious, associative processing. This article integrates theories of dual-processing and models of the business venturing (opportunity recognition, evaluation, and exploitation) in a model of entrepreneurial intuition, which links intuitive expertise, cognitive style, somatic state, and the affect heuristic with System 2 interventions and the contingencies of the decision environment. Six research propositions are offered with suggestions for how they can be tested. The theoretical and practical implications of entrepreneurial intuition are discussed in terms of the unfolding of a research agenda relating to this important but under-theorized and under-researched construct in work and organizational psychology
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