21,908 research outputs found

    Financial institutions and the wealth of nations: tales of development (discussion paper)

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    Interactions between economic development and financial development are studied by looking at the roles of financial institutions in selecting R&D projects (including for both imitation and innovation). Financial development is regarded as the evolution of the financing regimes. The effectiveness of R&D selection mechanisms depends on the institutions and the development stages of an economy. At higher development stages a financing regime with ex post selection capacity is more effective for innovation. However, this regime requires more decentralized decision-making, which in turn depend on contract enforcement. A financing regime with more centralized decision-making is less affected by contract enforcement but has no ex post selection capacity. Depending on the legal institutions, economies in equilibrium choose regimes that lead to different steady-state development levels. The financing regime of an economy also affects development dynamics through a ‘convergence effect’ and a ‘growth inertia effect’. A backward economy with a financing regime with centralized decision-making may catch up rapidly when the convergence effect and the growth inertia effect are in the same direction. However, this regime leads to large development cycles at later development stages. Empirical implications are discussed.postprin

    A new atmospheric aerosol phase equilibrium model (UHAERO): organic systems

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    In atmospheric aerosols, water and volatile inorganic and organic species are distributed between the gas and aerosol phases in accordance with thermodynamic equilibrium. Within an atmospheric particle, liquid and solid phases can exist at equilibrium. Models exist for computation of phase equilibria for inorganic/water mixtures typical of atmospheric aerosols; when organic species are present, the phase equilibrium problem is complicated by organic/water interactions as well as the potentially large number of organic species. We present here an extension of the UHAERO inorganic thermodynamic model (Amundson et al., 2006c) to organic/water systems. Phase diagrams for a number of model organic/water systems characteristic of both primary and secondary organic aerosols are computed. Also calculated are inorganic/organic/water phase diagrams that show the effect of organics on inorganic deliquescence behavior. The effect of the choice of activity coefficient model for organics on the computed phase equilibria is explored

    Geometric phase in open systems: beyond the Markov approximation and weak coupling limit

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    Beyond the quantum Markov approximation and the weak coupling limit, we present a general theory to calculate the geometric phase for open systems with and without conserved energy. As an example, the geometric phase for a two-level system coupling both dephasingly and dissipatively to its environment is calculated. Comparison with the results from quantum trajectory analysis is presented and discussed

    Determination of interfacial fracture toughness of bone–cement interface using sandwich Brazilian disks

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    AbstractThe long-term stability of cemented total hip replacements critically depends on the lasting integrity of the bond between bone and bone cement. Conventionally, the bonding strength of bone–cement is obtained by mechanical tests that tend to produce a large variability between specimens and test methods. In this work, interfacial fracture toughness of synthetic bone–cement interface has been studied using sandwiched Brazilian disk specimens. Experiments were carried out using polyurethane foams as substrates and a common bone cement as an interlayer. Selected loading angles from 0° to 25° were used to achieve full loading conditions from mode I to mode II. Finite element analyses were carried out to obtain the solutions for strain energy release rates at given phase angles associated with the experimental models. The effects of crack length on the measured interfacial fracture toughness were examined. Microscopic studies were also carried out to obtain the morphology of the fractured interfaces at selected loading angles.The implication of the results on the assessment of fixation in acetabular replacements is discussed in the light of preliminary work on bovine cancellous bone–cement interface

    Perceived width evaluation on interpolated line sources in a virtual urban square

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    The aim of this study is to investigate the relationship between the perceived width and different interpolation setups of a line source, and whether it is possible to reduce interpolations of a line source in a virtual open urban space. In order to auralise sound sources efficiently and accurately, the subjective evaluation was carried out in accordance with Virtual Reality (VR) with spatial audio. The results show that when the audible angle between adjacent interpolation points of a line source is lowered to 1◦ , the perceived width of the line source will significantly improve under VR experience. When the angle is less than 1◦ , the variation in points interpolation does not significantly affect the perceived width. This improvement may enhance the immersion during subjective evaluation, thus creating a more realistic experience

    Kraus representation for density operator of arbitrary open qubit system

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    We show that the time evolution of density operator of open qubit system can always be described in terms of the Kraus representation. A general scheme on how to construct the Kraus operators for an open qubit system is proposed, which can be generalized to open higher dimensional quantum systems.Comment: 5 pages, no figures. Some words are rephrase

    Secondary aerosol formation from atmospheric reactions of aliphatic amines

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    Although aliphatic amines have been detected in both urban and rural atmospheric aerosols, little is known about the chemistry leading to particle formation or the potential aerosol yields from reactions of gas-phase amines. We present here the first systematic study of aerosol formation from the atmospheric reactions of amines. Based on laboratory chamber experiments and theoretical calculations, we evaluate aerosol formation from reaction of OH, ozone, and nitric acid with trimethylamine, methylamine, triethylamine, diethylamine, ethylamine, and ethanolamine. Entropies of formation for alkylammonium nitrate salts are estimated by molecular dynamics calculations enabling us to estimate equilibrium constants for the reactions of amines with nitric acid. Though subject to significant uncertainty, the calculated dissociation equilibrium constant for diethylammonium nitrate is found to be sufficiently small to allow for its atmospheric formation, even in the presence of ammonia which competes for available nitric acid. Experimental chamber studies indicate that the dissociation equilibrium constant for triethylammonium nitrate is of the same order of magnitude as that for ammonium nitrate. All amines studied form aerosol when photooxidized in the presence of NOx with the majority of the aerosol mass present at the peak of aerosol growth consisting of aminium (R3NH+) nitrate salts, which repartition back to the gas phase as the parent amine is consumed. Only the two tertiary amines studied, trimethylamine and triethylamine, are found to form significant non-salt organic aerosol when oxidized by OH or ozone; calculated organic mass yields for the experiments conducted are similar for ozonolysis (15% and 5% respectively) and photooxidation (23% and 8% respectively). The non-salt organic aerosol formed appears to be more stable than the nitrate salts and does not quickly repartition back to the gas phase
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