PageRank model of opinion formation on Ulam networks

We consider a PageRank model of opinion formation on Ulam networks, generated by the intermittency map and the typical Chirikov map. The Ulam networks generated by these maps have certain similarities with such scale-free networks as the World Wide Web (WWW), showing an algebraic decay of the PageRank probability. We find that the opinion formation process on Ulam networks have certain similarities but also distinct features comparing to the WWW. We attribute these distinctions to internal differences in network structure of the Ulam and WWW networks. We also analyze the process of opinion formation in the frame of generalized Sznajd model which protects opinion of small communities.Comment: 7 pages, 6 figures. Updated version for publicatio

Download relaxation dynamics on the WWW following newspaper publication of URL

A few key properties of the World-Wide-Web (WWW) has been established indicating the lack of any characteristic scales for the WWW, both in its topology and in its dynamics. Here, we report an experiment which quantifies another power law describing the dynamical response of the WWW to a Dirac-like perturbation, specifically how the popularity of a web site evolves and relaxes as a function of time, in response to the publication of a notice/advertisement in a newspaper. Following the publication of an interview of the authors by a journalist which contained our URL, we monitored the rate of downloads of our papers and found it to obey a $1/t^b$ power law with exponent $b=0.58\pm 0.03$. This small exponent implies long-term memory and can be rationalized using the concept of persistence, which specifies how long a relaxing dynamical system remains in a neighborhood of its initial configuration.Comment: 5 pages including 3 figures. Subm. to Natur

Singlet Polarization Functions at O(\alpha_s^2)

We consider the three-loop singlet diagrams induced by axial-vector, scalar and pseudo-scalar currents. Expansions for small and large external momentum $q$ are presented. They are used in combination with conformal mapping and Pad\'e approximations in order to arrive at results for the polarization functions valid for all $q^2$. Results are presented for the imaginary parts which are directly related to physical quantities like the production of top quarks or the decay of scalar or pseudo-scalar Higgs bosons.Comment: LaTeX, 15 pages, 10 figures included as ps-files. The complete paper is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ , or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints

Asymptotics of the perturbative series for f_{B^*}/f_B

We investigate the structure of the leading IR renormalon singularity in the QCD/HQET matching coefficients for heavy-light quark currents beyond the large-\beta_0 limit. From this result, we derive the large-order behaviour of the perturbative series for these coefficients, and for ratios of meson matrix elements, such as f_{B^*}/f_B.Comment: 45 pages, 2 eps figures. v2: small corrections, reference added. v3: reference added. v4: errors in some equations of Appendix B, in (5.8) and Table 2 corrected, numerical changes are very small. Paper also available from http://www-ttp.physik.uni-karlsruhe.de/Preprints

Differential expression analysis for sequence count data

*Motivation:* High-throughput nucleotide sequencing provides quantitative readouts in assays for RNA expression (RNA-Seq), protein-DNA binding (ChIP-Seq) or cell counting (barcode sequencing). Statistical inference of differential signal in such data requires estimation of their variability throughout the dynamic range. When the number of replicates is small, error modelling is needed to achieve statistical power.

*Results:* We propose an error model that uses the negative binomial distribution, with variance and mean linked by local regression, to model the null distribution of the count data. The method controls type-I error and provides good detection power. 

*Availability:* A free open-source R software package, _DESeq_, is available from the Bioconductor project and from "http://www-huber.embl.de/users/anders/DESeq":http://www-huber.embl.de/users/anders/DESeq

Adoption of WWWPages Among New Zealand Wineries

This paper uses diffusion of innovations theory to explain the adoption of WWW pages amongst wineries and includes the criticisms of diffusion of innovations theory such as pro-innovation bias, individual bias, recall problems and equity issues .The findings from two polls of WWW sites for NZ wineries undertaken six months apart are reported. The information collected indicates the trends in the adoption of WWW pages amongst small businesses over the 1999 – 2000 year. Trends in WWW page currency, design, content and administration are reported

Second Order QCD Corrections to Γ(t→Wb)\Gamma(t \to Wb)

Corrections of $O(\alpha_s^2)$ to the decay of the top quark into a W boson and a bottom quark are calculated. The method is based on an expansion of the top quark propagator for small external momentum, q, as compared to the top quark mass, M_t. The physical point q^2 = M_t^2 is reached through Pad\'e approximations. The described method allows to take effects induced by a finite W boson mass into account. The numerical relevance of the result is discussed. Important cross-checks against recent results for the decay rate $b \to u l \bar\nu$ and the two-loop QED corrections to $\mu$-decay are performed.Comment: Latex, 21 pages, 1 figure included as ps-file. Minor changes; reference added. Version to be published in PRD. The complete paper is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ttp99/ttp99-25/ or via www at http://www-ttp.physik.uni-karlsruhe.de/Preprints