4,029 research outputs found

    Computational phylogenetics and the classification of South American languages

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    In recent years, South Americanist linguists have embraced computational phylogenetic methods to resolve the numerous outstanding questions about the genealogi- cal relationships among the languages of the continent. We provide a critical review of the methods and language classification results that have accumulated thus far, emphasizing the superiority of character-based methods over distance-based ones and the importance of develop- ing adequate comparative datasets for producing well- resolved classifications

    What affects the Russian regional governments'propensity to subsidize?

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    Subsidies funded by Russia's regional governments represented about 5.2 percent of GDP in 1995, almost triple the 2 percent of GDP in subsidies funded by the federal government. Regional policies vary greatly, influenced more by local factors than by the federal government. To find out what affects the regional governments'propensity to subsidize, the authors examined available data for 1992-95, asking: How great is the variation across regions in the incidence of subsidies, and what are recent trends in such variation? What are the relative influences of supply and demand factors in shaping the current levels of subsidy? How do federal budget transfers affect regionally funded subsidies to local enterprises? To what extent are federal transfers distortionary, encouraging subsidies and postphoning the liberalization of local markets? Their findings: 1) Regional wealth and federal budget transfers to regional governments are two of the most important determinants of regional propensity to subsidize. 2) Even when regional budgetary wealth is controlled for, depressed regions (those affected most by industrial decline and unemployment) tend to spend less on subsidies than regions with more favorable economies. 3) Federal budget transfers are quite distortionary, that is, they encourage regional governments to continue subsidy policies and postpone structural reforms. In fact, federal transfers tend to be concerned in regions with the most distortionary policies. 4) Housing receives the lion's share of total regional subsidies, and there are greater disparities in housing subsidies than in agricultural subsidies. 5) Housing and transportation subsidies are strongly counter-equalizing: Households in wealthier regions receive more in housing subsidies and rural populations have less access to those subsidies, so up to 30 percent of regional subsidies are questionable in terms of equity. 6) Federal transfers have less effect on regional subsidies in agriculture, which are influenced more by the region's own tax base and its share of rural population or by such factors as the political influence of local interest groups. 7) To accelerate structural reforms, the federal government might consider reducing the number of recipients of federal budget transfers and changing the rules of allocation of the transfers, in particular by introducing conditional transfers linked to increases in cost recovery.Economic Theory&Research,Banks&Banking Reform,Municipal Financial Management,Public Sector Economics&Finance,Environmental Economics&Policies,Banks&Banking Reform,Municipal Financial Management,Public Sector Economics&Finance,Environmental Economics&Policies,Economic Theory&Research

    Calculation of the current response in a nanojunction for an arbitrary time-dependent bias: application to the molecular wire

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    Recently [Phys. Rev. B 91, 125433 (2015)] we derived a general formula for the time-dependent quantum electron current through a molecular junction subject to an arbitrary time-dependent bias within the Wide Band Limit Approximation (WBLA) and assuming a single particle Hamiltonian. Here we present an efficient numerical scheme for calculating the current and particle number. Using the Pad\'e expansion of the Fermi function, it is shown that all frequency integrals occurring in the general formula for the current can be removed analytically. Furthermore, when the bias in the reservoirs is assumed to be sinusoidal it is possible to manipulate the general formula into a form containing only summations over special functions. To illustrate the method, we consider electron transport through a one-dimensional molecular wire coupled to two leads subject to out-of-phase biases. We also investigate finite size effects in the current response and particle number that results from the switch-on of such a bias

    Rate of cluster decomposition via Fermat-Steiner point

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    In quantum field theory with a mass gap correlation function between two spatially separated operators decays exponentially with the distance. This fundamental result immediately implies an exponential suppression of all higher point correlation functions, but the predicted exponent is not optimal. We argue that in a general quantum field theory the optimal suppression of a three-point function is determined by total distance from the operator locations to the Fermat-Steiner point. Similarly, for the higher point functions we conjecture the optimal exponent is determined by the solution of the Euclidean Steiner tree problem. We discuss how our results constrain operator spreading in relativistic theories.Comment: 16 pages; journal version, appendix A adde
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