12,211 research outputs found

    The residue current of a codimension three complete intersection

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    Let f1f_1, f2f_2, and f3f_3 be holomorphic functions on a complex manifold and assume that the common zero set of the fjf_j has maximal codimension, i.e., that it is a complete intersection. We prove that the iterated Mellin transform of the residue integral has an analytic continuation to a neighborhood of the origin in C3\mathbb{C}^3. We prove also that the natural regularization of the residue current converges unrestrictedly

    Relating Turing's Formula and Zipf's Law

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    An asymptote is derived from Turing's local reestimation formula for population frequencies, and a local reestimation formula is derived from Zipf's law for the asymptotic behavior of population frequencies. The two are shown to be qualitatively different asymptotically, but nevertheless to be instances of a common class of reestimation-formula-asymptote pairs, in which they constitute the upper and lower bounds of the convergence region of the cumulative of the frequency function, as rank tends to infinity. The results demonstrate that Turing's formula is qualitatively different from the various extensions to Zipf's law, and suggest that it smooths the frequency estimates towards a geometric distribution.Comment: 9 pages, uuencoded, gzipped PostScript; some typos remove

    A pullback operation on a class of currents

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    For any holomorphic map f ⁣:XYf\colon X\to Y between a complex manifold XX and a complex Hermitian manifold YY we extend the pullback ff^* from smooth forms to a class of currents in a cohomologically sound way. We provide a basic calculus for this pullback. The class of currents we consider contains in particular the Lelong current of any analytic cycle. Our pullback depends in general on the Hermitian structure of YY but coincides with the usual pullback of currents in case ff is a submersion. The construction is based on the Gysin mapping in algebraic geometry.Comment: Theorem 1.2 is improve

    Proposal for non-local electron-hole turnstile in the Quantum Hall regime

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    We present a theory for a mesoscopic turnstile that produces spatially separated streams of electrons and holes along edge states in the quantum Hall regime. For a broad range of frequencies in the non-adiabatic regime the turnstile operation is found to be ideal, producing one electron and one hole per cycle. The accuracy of the turnstile operation is characterized by the fluctuations of the transferred charge per cycle. The fluctuations are found to be negligibly small in the ideal regime.Comment: 4+ pages, 2 figure

    Legal Education: Extent to Which “Know-How” in Practice Should Be Taught in Law Schools

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    In order to attract pedestrians to travel with public transport instead of private cars, the layout of interchange stations is important and should be designed in an effective way. Microscopic simulation of pedestrians can be used to evaluate different layout scenarios or a future increase in flow. The simulation software Viswalk was investigated, where the movements of pedestrians are based on a social force model,. The purpose of this thesis was to investigate simulated walking speeds for different flow levels and to investigate the effects of dividing pedestrians into types with different desired speeds. The aim was to find a desired speed distribution that can be used for different flow levels. Field studies have been performed to collect pedestrian traffic data with a video camera at Stockholm Central Station. Two disjoint flow levels were identified and used to investigate if the same desired speed distribution could be used for different flow levels. The average observed walking speed was 1.33 metres per second at the low flow level and 1.25 metres per second at the high flow level. The error was 4.5 percent between the average observed walking speed and the average simulated walking speed when the optimal desired speed distribution at the low flow level was used at the high flow level. Effects of using different desired speed distributions for different pedestrian types have also been investigated. The error between the average of the observed and the simulated walking speeds varies between 2.3 and 4.1 percent when dividing pedestrians into different types when the optimal desired speed distributions at the low flow level are used at the high flow level. A sensitivity analysis of some parameters of the social force model in Viswalk has also been performed. Several adjustments of the parameters show that some parameters had great impact of the simulated walking speeds. The final conclusion is that the parameter configuration and how the pedestrians are divided into different types affect the average simulated walking speed

    Tagging the Teleman Corpus

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    Experiments were carried out comparing the Swedish Teleman and the English Susanne corpora using an HMM-based and a novel reductionistic statistical part-of-speech tagger. They indicate that tagging the Teleman corpus is the more difficult task, and that the performance of the two different taggers is comparable.Comment: 14 pages, LaTeX, to appear in Proceedings of the 10th Nordic Conference of Computational Linguistics, Helsinki, Finland, 199

    Full counting statistics of incoherent Andreev transport

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    We study the full counting statistics of heterostructures consisting of normal metal parts connected to a superconducting terminal. Assuming that coherent superconducting correlations are suppressed in the normal metals we show, using Keldysh-Nambu Green's functions, that the system can be mapped onto a purely normal system with twice the number of elements. For a superconducting beam splitter with several normal terminals we obtain general results for the counting statistics.Comment: 7 pages, submitted to Europhys. Let
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