2,617 research outputs found

    Spatial Econometric Issues for Bio-Economic and Land-Use Modeling

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    We survey the literature on spatial bio-economic and land-use modelling and review thematic developments. Unobserved site-specific heterogeneity is common in almost all of the surveyed works. Heterogeneity appears also to be a significant catalyst engendering significant methodological innovation. To better equip prototypes to adequately incorporate heterogeneity, we consider a smorgasbord of extensions. We highlight some problems arising with their application; provide Bayesian solutions to some; and conjecture solutions for others.spatial econometrics, bio-economic and land-use modelling, Bayesian solution, Land Economics/Use,

    Boundary interactions changing operators and dynamical correlations in quantum impurity problems

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    Recent developments have made possible the computation of equilibrium dynamical correlators in quantum impurity problems. In many situations however, one is rather interested in correlators subject to a non equilibrium initial preparation; this is the case for instance for the occupation probability P(t)P(t) in the double well problem of dissipative quantum mechanics (DQM). We show in this paper how to handle this situation in the framework of integrable quantum field theories by introducing ``boundary interactions changing operators''. We determine the properties of these operators by using an axiomatic approach similar in spirit to what is done for form-factors. This allows us to obtain new exact results for P(t)P(t); for instance, we find that that at large times (or small gg), the leading behaviour for g < 1/2} is P(t)∝e−Γtcos⁥ΩtP(t)\propto e^{-\Gamma t}\cos\Omega t, with the universal ratio. Ω/Γ=cotâĄÏ€g/2(1−g)\Omega/\Gamma = \cot {\pi g}/{2(1-g)}.Comment: 4 pages, revte

    Exact Friedel oscillations in the g=1/2 Luttinger liquid

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    A single impurity in the 1D Luttinger model creates a local modification of the charge density analogous to the Friedel oscillations. In this paper, we present an exact solution of the case g=12g={1\over 2} (the equivalent of the Toulouse point) at any temperature TT and impurity coupling, expressing the charge density in terms of a hypergeometric function. We find in particular that at T=0T=0, the oscillatory part of the density goes as ln⁡x\ln x at small distance and x−1/2x^{-1/2} at large distance.Comment: 1 reference added. 13 pages, harvma

    Coherence correlations in the dissipative two-state system

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    We study the dynamical equilibrium correlation function of the polaron-dressed tunneling operator in the dissipative two-state system. Unlike the position operator, this coherence operator acts in the full system-plus-reservoir space. We calculate the relevant modified influence functional and present the exact formal expression for the coherence correlations in the form of a series in the number of tunneling events. For an Ohmic spectral density with the particular damping strength K=1/2K=1/2, the series is summed in analytic form for all times and for arbitrary values of temperature and bias. Using a diagrammatic approach, we find the long-time dynamics in the regime K<1K<1. In general, the coherence correlations decay algebraically as t−2Kt^{-2K} at T=0. This implies that the linear static susceptibility diverges for K≀1/2K\le 1/2 as T→0T\to 0, whereas it stays finite for K>1/2K>1/2 in this limit. The qualitative differences with respect to the asymptotic behavior of the position correlations are explained.Comment: 19 pages, 4 figures, to be published in Phys. Rev.

    Transfer of recessive skr crossability trait into well-adapted French wheat cultivar Barok through marker-assisted backcrossing method

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    In order to increase genetic diversity in cereals, interspecific or even intergeneric crosses are worthwhile, especially wheat by rye crosses for triticale production. However, these crosses often fail due to inhibiting genes. To overcome this obstacle, crossability trait, present in a few wheat cultivars, can be transferred into other wheat lines of agronomical interest. Nevertheless, this transfer remains tedious through conventional backcrossing methods because it is a recessive trait, which requires selfing generations and complex evaluation by many crosses. Here, we present a marker-assisted backcrossing method to transfer this trait more quickly and easily. We chose to introduce the recessive crossability skr, located on chromosome 5BS and originating from Asian wheat, into Barok, a non-crossable French wheat cultivar, with good agronomic characteristics. Six molecular markers, close to the Skr locus, were used to check the transfer of the gene at each of the three backcrosses, without selfing generation nor crosses with rye. Finally, we crossed the predicted crossable lines with rye to validate their crossability. We obtained sixteen lines, morphologically similar to Barok, exhibiting high crossability rate (30%). The markers were thus efficient to transfer the skr crossability but they remain too far from the Skr locus to be considered as diagnostic markers. Indeed, genotyping and phenotyping on other wheat cultivars showed some discrepancies. Nevertheless, this opens the way to enhance genetic diversity more easily and to improve traits of agronomic interest in triticale or wheat as well as to study further barriers to intergeneric crosses

    Form-factors computation of Friedel oscillations in Luttinger liquids

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    We show how to analytically determine for g≀1/2g\leq 1/2 the "Friedel oscillations" of charge density by a single impurity in a 1D Luttinger liquid of spinless electrons.Comment: Revtex, epsf, 4pgs, 2fig

    MASCARA-2 b: A hot Jupiter transiting the mV=7.6m_V=7.6 A-star HD185603

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    In this paper we present MASCARA-2 b, a hot Jupiter transiting the mV=7.6m_V=7.6 A2 star HD 185603. Since early 2015, MASCARA has taken more than 1.6 million flux measurements of the star, corresponding to a total of almost 3000 hours of observations, revealing a periodic dimming in the flux with a depth of 1.3%1.3\%. Photometric follow-up observations were performed with the NITES and IAC80 telescopes and spectroscopic measurements were obtained with the Hertzsprung SONG telescope. We find MASCARA-2 b orbits HD 185603 with a period of 3.474119−0.000006+0.000005 days3.474119^{+0.000005}_{-0.000006}~\rm{days} at a distance of 0.057±0.006 AU0.057 \pm 0.006~\rm{AU}, has a radius of 1.83±0.07 RJ1.83 \pm 0.07~\rm{R}_{\rm{J}} and place a 99%99\% upper limit on the mass of <17 MJ< 17~\rm{M}_{\rm{J}}. HD 185603 is a rapidly rotating early-type star with an effective temperature of 8980−130+90 K8980^{+90}_{-130}~\rm{K} and a mass and radius of 1.89−0.05+0.06 M⊙1.89^{+0.06}_{-0.05}~M_\odot, 1.60±0.06 R⊙1.60 \pm 0.06~R_\odot, respectively. Contrary to most other hot Jupiters transiting early-type stars, the projected planet orbital axis and stellar spin axis are found to be aligned with λ=0.6±4∘\lambda=0.6 \pm 4^\circ. The brightness of the host star and the high equilibrium temperature, 2260±50 K2260 \pm 50~\rm{K}, of MASCARA-2 b make it a suitable target for atmospheric studies from the ground and space. Of particular interest is the detection of TiO, which has recently been detected in the similarly hot planets WASP-33 b and WASP-19 b.Comment: 8 pages, 4 figures, Accepted for publication in A&

    The Transition Between Quantum Coherence and Incoherence

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    We show that a transformed Caldeira-Leggett Hamltonian has two distinct families of fixed points, rather than a single unique fixed point as often conjectured based on its connection to the anisotropic Kondo model. The two families are distinguished by a sharp qualitative difference in their quantum coherence properties and we argue that this distinction is best understood as the result of a transition in the model between degeneracy and non-degeneracy in the spectral function of the ``spin-flip'' operator.Comment: some typos corrected and a reference adde

    Solving 1d plasmas and 2d boundary problems using Jack polynomials and functional relations

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    The general one-dimensional ``log-sine'' gas is defined by restricting the positive and negative charges of a two-dimensional Coulomb gas to live on a circle. Depending on charge constraints, this problem is equivalent to different boundary field theories. We study the electrically neutral case, which is equivalent to a two-dimensional free boson with an impurity cosine potential. We use two different methods: a perturbative one based on Jack symmetric functions, and a non-perturbative one based on the thermodynamic Bethe ansatz and functional relations. The first method allows us to compute explicitly all coefficients in the virial expansion of the free energy and the experimentally-measurable conductance. Some results for correlation functions are also presented. The second method provides in particular a surprising fluctuation-dissipation relation between the free energy and the conductance.Comment: 19 page
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