12,255 research outputs found
The residue current of a codimension three complete intersection
Let , , and be holomorphic functions on a complex manifold
and assume that the common zero set of the 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 . We prove also that the natural regularization of the
residue current converges unrestrictedly
Relating Turing's Formula and Zipf's Law
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
For any holomorphic map between a complex manifold and a
complex Hermitian manifold we extend the pullback 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 but coincides with the usual pullback
of currents in case 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
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
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
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
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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