1,498 research outputs found

    Fat residue and use-wear found on Acheulian biface and scraper associated with butchered elephant remains at the site of Revadim, Israel

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    The archaeological record indicates that elephants must have played a significant role in early human diet and culture during Palaeolithic times in the Old World. However, the nature of interactions between early humans and elephants is still under discussion. Elephant remains are found in Palaeolithic sites, both open-air and cave sites, in Europe, Asia, the Levant, and Africa. In some cases elephant and mammoth remains indicate evidence for butchering and marrow extraction performed by humans. Revadim Quarry (Israel) is a Late Acheulian site where elephant remains were found in association with characteristic Lower Palaeolithic flint tools. In this paper we present results regarding the use of Palaeolithic tools in processing animal carcasses and rare identification of fat residue preserved on Lower Palaeolithic tools. Our results shed new light on the use of Palaeolithic stone tools and provide, for the first time, direct evidence (residue) of animal exploitation through the use of an Acheulian biface and a scraper. The association of an elephant rib bearing cut marks with these tools may reinforce the view suggesting the use of Palaeolithic stone tools in the consumption of large game

    Inflation Targeting and the Anchoring of Inflation Expectations in The Western Hemisphere

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    We investigate the extent to which long-run inflation expectations are well anchored in three western hemisphere countries—Canada, Chile, and the United States—using a high-frequency event-study analysis. Specifically, we use daily data on far-ahead forward inflation compensation—the difference between forward rates on nominal and inflation-indexed bonds—as an indicator of financial market perceptions of inflation risk and the expected level of inflation at long horizons. For the United States, we find that far-ahead forward inflation compensation reacts significantly to macroeconomic data releases, suggesting that long-run inflation expectations are not completely anchored. In contrast, the Canadian inflation compensation data do not exhibit significant sensitivity to either Canadian or U.S. macroeconomic news, consistent with the view that inflation targeting in Canada has been successful in anchoring long-run inflation expectations. Finally, while the requisite data for Chile is only available for a limited sample period (2002-2005), our results are consistent with the hypothesis that inflation targeting in Chile has also succeeded in anchoring long-run inflation expectations.

    Transillumination imaging through scattering media by use of photorefractive polymers

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    We demonstrate the use of a near-infrared-sensitive photorefractive polymer with high efficiency for imaging through scattering media, using an all-optical holographic time gate. Imaging through nine scattering mean free paths is performed at 800 nm with a mode-locked continuous-wave Ti:sapphire laser

    Magnetism in one-dimensional quantum dot arrays

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    We employ the density functional Kohn-Sham method in the local spin-density approximation to study the electronic structure and magnetism of quasi one-dimensional periodic arrays of few-electron quantum dots. At small values of the lattice constant, the single dots overlap, forming a non-magnetic quantum wire with nearly homogenous density. As the confinement perpendicular to the wire is increased, i.e. as the wire is squeezed to become more one-dimensional, it undergoes a spin-Peierls transition. Magnetism sets in as the quantum dots are placed further apart. It is determined by the electronic shell filling of the individual quantum dots. At larger values of the lattice constant, the band structure for odd numbers of electrons per dot indicates that the array could support spin-polarized transport and therefore act as a spin filter.Comment: 11 pages, 6 figure

    Fracturing highly disordered materials

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    We investigate the role of disorder on the fracturing process of heterogeneous materials by means of a two-dimensional fuse network model. Our results in the extreme disorder limit reveal that the backbone of the fracture at collapse, namely the subset of the largest fracture that effectively halts the global current, has a fractal dimension of 1.22±0.011.22 \pm 0.01. This exponent value is compatible with the universality class of several other physical models, including optimal paths under strong disorder, disordered polymers, watersheds and optimal path cracks on uncorrelated substrates, hulls of explosive percolation clusters, and strands of invasion percolation fronts. Moreover, we find that the fractal dimension of the largest fracture under extreme disorder, df=1.86±0.01d_f=1.86 \pm 0.01, is outside the statistical error bar of standard percolation. This discrepancy is due to the appearance of trapped regions or cavities of all sizes that remain intact till the entire collapse of the fuse network, but are always accessible in the case of standard percolation. Finally, we quantify the role of disorder on the structure of the largest cluster, as well as on the backbone of the fracture, in terms of a distinctive transition from weak to strong disorder characterized by a new crossover exponent.Comment: 5 pages, 4 figure

    INFLATION TARGETING AND THE ANCHORING OF INFLATION EXPECTATIONS IN THE WESTERN HEMISPHERE

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    We investigate the extent to which long-run inflation expectations are well anchored in Canada, Chile, and the United States, using a high-frequency event-study analysis. Specifically, we use daily data on far-ahead forward inflation compensation as an indicator of financial market perceptions of inflation risk and the expected level of inflation at long horizons. For the U.S., we find that far-ahead forward inflation compensation reacts significantly to macroeconomic data releases, implying that long-run inflation expectations are not completely anchored. In contrast, the Canadian inflation compensation data does not exhibit significant sensitivity to either Canadian or U.S. macroeconomic news, confirming that inflation targeting in Canada has succeeded in anchoring long-run inflation expectations. Finally, while the requisite data for Chile is available only for a limited sample period (2002-05), our results are consistent with the hypothesis that inflation targeting in Chile has also succeeded in anchoring long-run inflation expectations.

    d0 Perovskite-Semiconductor Electronic Structure

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    We address the low-energy effective Hamiltonian of electron doped d0 perovskite semiconductors in cubic and tetragonal phases using the k*p method. The Hamiltonian depends on the spin-orbit interaction strength, on the temperature-dependent tetragonal distortion, and on a set of effective-mass parameters whose number is determined by the symmetry of the crystal. We explain how these parameters can be extracted from angle resolved photo-emission, Raman spectroscopy, and magneto-transport measurements and estimate their values in SrTiO3

    Asymptotic statistics of the n-sided planar Poisson-Voronoi cell. I. Exact results

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    We achieve a detailed understanding of the nn-sided planar Poisson-Voronoi cell in the limit of large nn. Let p_n{p}\_n be the probability for a cell to have nn sides. We construct the asymptotic expansion of logp_n\log {p}\_n up to terms that vanish as nn\to\infty. We obtain the statistics of the lengths of the perimeter segments and of the angles between adjoining segments: to leading order as nn\to\infty, and after appropriate scaling, these become independent random variables whose laws we determine; and to next order in 1/n1/n they have nontrivial long range correlations whose expressions we provide. The nn-sided cell tends towards a circle of radius (n/4\pi\lambda)^{\half}, where λ\lambda is the cell density; hence Lewis' law for the average area A_nA\_n of the nn-sided cell behaves as A_ncn/λA\_n \simeq cn/\lambda with c=1/4c=1/4. For nn\to\infty the cell perimeter, expressed as a function R(ϕ)R(\phi) of the polar angle ϕ\phi, satisfies d2R/dϕ2=F(ϕ)d^2 R/d\phi^2 = F(\phi), where FF is known Gaussian noise; we deduce from it the probability law for the perimeter's long wavelength deviations from circularity. Many other quantities related to the asymptotic cell shape become accessible to calculation.Comment: 54 pages, 3 figure
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