16,125 research outputs found

    The Behavioral Firm and Its Internal Game: Evolutionary Dynamics of Decision Making

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    In this paper the firm is analyzed and modeled as a set of different subcoalitions (agents) each with their own objectives. It examines how the goals can be conflicting and in turn how this influences the payoff structure of the subcoalitions given that they follow 'simple' decision rules, i.e. rules of thumb. This implies that the subcoalitions act in aboundedly rational way. To see how these decision making procedures evolve we make use of an (evolutionary) dynamic game theoretical framework. Consequently, the main aim is to address the issue of modeling the dynamic and adaptive nature of the subcoalitions

    The effect of core polarization on longitudinal form factors in 10^{10}B

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    Electron scattering Coulomb form factors for the single-particle quadrupole transitions in pp-shell 10^{10}B nucleus have been studied. Core polarization effects are included through a microscopic theory that includes excitations from the core orbits up to higher orbits with 2\hbarω\omega excitations. The modified surface delta interaction (MSDI) is employed as a residual interaction. The effect of core polarization is found essential in both the transition strengths and momentum transfer dependence of form factors, and gives a remarkably good agreement with the measured data with no adjustable parameters.Comment: 4 pages, 5 figure

    Laboratory mid-IR spectra of equilibrated and igneous meteorites. Searching for observables of planetesimal debris

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    Meteorites contain minerals from Solar System asteroids with different properties (like size, presence of water, core formation). We provide new mid-IR transmission spectra of powdered meteorites to obtain templates of how mid-IR spectra of asteroidal debris would look like. This is essential for interpreting mid-IR spectra of past and future space observatories, like the James Webb Space Telescope. We show that the transmission spectra of wet and dry chondrites, carbonaceous and ordinary chondrites and achondrite and chondrite meteorites are distinctly different in a way one can distinguish in astronomical mid-IR spectra. The two observables that spectroscopically separate the different meteorites groups (and thus the different types of parent bodies) are the pyroxene-olivine feature strength ratio and the peak shift of the olivine spectral features due to an increase in the iron concentration of the olivine

    Evidence for precession of the isolated neutron star RX J0720.4-3125

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    The XMM-Newton spectra of the isolated neutron star RX J0720.4-3125 obtained over 4.5 years can be described by sinusoidal variations in the inferred blackbody temperature, the size of the emitting area and the depth of the absorption line with a period of 7.1 +/- 0.5 years, which we suggest to be the precession period of the neutron star. Precession of a neutron star with two hot spots of different temperature and size, probably not located exactly in antipodal positions, may account for the variations in the X-ray spectra, changes in the pulsed fraction, shape of the light curve and the phase-lag between soft and hard energy bands observed from RX J0720.4-3125. An independent sinusoidal fit to published and new pulse timing residuals from a coherent analysis covering ~12 years yields a consistent period of 7.7 +/- 0.6 years supporting the precession model.Comment: Accepted for publication in A&A Letters, 5 pages, 5 figure

    Towards a Soil Information System with quantified accuracy : a prototype for mapping continuous soil properties

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    This report describes the potential and functionality of software for spatial analysis, prediction and stochastic simulation of continuous soil properties using data from the Dutch Soil Information System (BIS). A geostatistical framework and R codes were developed. The geostatistical model of a soil property has a deterministic component representing the mean value within a soil category, and a stochastic component of standardized residuals. The standardized residuals are interpolated or simulated based on the simple kriging system. The software was tested in four case studies: exchangeable soil pH, clay content, organic matter content and Mean Spring Water table depth (MSW). It is concluded that the geostatistical framework and R codes developed in this study enable to predict values of continuous soil properties spatially, and to quantify the inaccuracy of these predictions. The inaccuracy of a spatial prediction at a certain location is quantified by the kriging variance, which can be interpreted as an indication of the uncertainty about the true value

    Practical Aspects of Carbon-Carbon Cross-Coupling Reactions Using Heteroarenes

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    The use of cross-coupling reactions for the preparation of alkylated and arylated heteroaromatic compounds has increased tremendously over the past two decades. This has been driven on the one hand by the increasingly complex structures of new drugs, most of which contain one or more heterocyclic motifs. On the other hand, the development of new catalysts and reaction conditions for these reactions has rendered even the most unreactive of heteroarenes amenable to cross-coupling chemistry. Not only have new bulky electron-donating ligands been created that allow the coupling of aryl chlorides under mild conditions, but also the use of ligand-free palladium, in particular at very low doses, sometimes called homeopathic palladium, has served to bring down the cost of these reactions. More recent and enabling developments are the use of catalysts based on cheap metals such as nickel, copper, and iron. Scale-up issues are availability and cost of starting materials, cost of the catalysts (related to cost of the metal and the ligand, intrinsic activity and stability of the catalyst), solvent choice, and removal of the metal t

    The Astrophysical Multipurpose Software Environment

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    We present the open source Astrophysical Multi-purpose Software Environment (AMUSE, www.amusecode.org), a component library for performing astrophysical simulations involving different physical domains and scales. It couples existing codes within a Python framework based on a communication layer using MPI. The interfaces are standardized for each domain and their implementation based on MPI guarantees that the whole framework is well-suited for distributed computation. It includes facilities for unit handling and data storage. Currently it includes codes for gravitational dynamics, stellar evolution, hydrodynamics and radiative transfer. Within each domain the interfaces to the codes are as similar as possible. We describe the design and implementation of AMUSE, as well as the main components and community codes currently supported and we discuss the code interactions facilitated by the framework. Additionally, we demonstrate how AMUSE can be used to resolve complex astrophysical problems by presenting example applications.Comment: 23 pages, 25 figures, accepted for A&
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