185 research outputs found

    Crafting a Systematic Literature Review on Open-Source Platforms

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    This working paper unveils the crafting of a systematic literature review on open-source platforms. The high-competitive mobile devices market, where several players such as Apple, Google, Nokia and Microsoft run a platforms- war with constant shifts in their technological strategies, is gaining increasing attention from scholars. It matters, then, to review previous literature on past platforms-wars, such as the ones from the PC and game-console industries, and assess its implications to the current mobile devices platforms-war. The paper starts by justifying the purpose and rationale behind this literature review on open-source platforms. The concepts of open-source software and computer-based platforms were then discussed both individually and in unison, in order to clarify the core-concept of 'open-source platform' that guides this literature review. The detailed design of the employed methodological strategy is then presented as the central part of this paper. The paper concludes with preliminary findings organizing previous literature on open-source platforms for the purpose of guiding future research in this area.Comment: As presented in 10th IFIP WG 2.13 International Conference on Open Source Systems, OSS 2014, San Jos\'e, Costa Rica, May 6-9, 201

    Analysis of antigenic relationships among influenza virus strains using a taxonomic cluster procedure. Comparison of three kinds of antibody preparations.

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    Hemagglutination inhibiting (HI) monoclonal antibody preparations (MA) were raised against six influenza A (H3N2) strains from the period 1977-1982. Twenty-three hybridomas were selected and titrated in HI assays against these strains and against 18 influenza A (H3N2) viruses isolated in The Netherlands during the seasons 1981-1982 and 1982-1983. Similar HI tests were performed with conventional post-infection ferret antisera and with ferret antisera adsorbed with heterologous strains of influenza A (H3N2) virus. The resulting serological data were subjected to a computerized taxonomic cluster procedure based on the Euclidean distance between viruses. With respect to the degree of separation between clusters the unadsorbed ferret antisera were inferior to the adsorbed antisera whereas the MA were superior to both. Our results demonstrate that computer programs based on numerical taxonomy can be helpful in processing large numbers of serological data and that MA are indispensable in epidemiological and diagnostic influenza studies

    Analysis of Agglomerative Clustering

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    The diameter kk-clustering problem is the problem of partitioning a finite subset of Rd\mathbb{R}^d into kk subsets called clusters such that the maximum diameter of the clusters is minimized. One early clustering algorithm that computes a hierarchy of approximate solutions to this problem (for all values of kk) is the agglomerative clustering algorithm with the complete linkage strategy. For decades, this algorithm has been widely used by practitioners. However, it is not well studied theoretically. In this paper, we analyze the agglomerative complete linkage clustering algorithm. Assuming that the dimension dd is a constant, we show that for any kk the solution computed by this algorithm is an O(logk)O(\log k)-approximation to the diameter kk-clustering problem. Our analysis does not only hold for the Euclidean distance but for any metric that is based on a norm. Furthermore, we analyze the closely related kk-center and discrete kk-center problem. For the corresponding agglomerative algorithms, we deduce an approximation factor of O(logk)O(\log k) as well.Comment: A preliminary version of this article appeared in Proceedings of the 28th International Symposium on Theoretical Aspects of Computer Science (STACS '11), March 2011, pp. 308-319. This article also appeared in Algorithmica. The final publication is available at http://link.springer.com/article/10.1007/s00453-012-9717-

    Search for Λc+pK+π\Lambda_c^+ \to p K^+ \pi^- and Ds+K+K+πD_s^+ \to K^+ K^+ \pi^- Using Genetic Programming Event Selection

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    We apply a genetic programming technique to search for the double Cabibbo suppressed decays Λc+pK+π\Lambda_c^+ \to p K^+ \pi^- and Ds+K+K+πD_s^+ \to K^+ K^+ \pi^-. We normalize these decays to their Cabibbo favored partners and find BR(\text{BR}(\Lambda_c^+ \to p K^+ \pi^-)/BR()/\text{BR}(\Lambda_c^+ \to p K^- \pi^+)=(0.05±0.26±0.02)) = (0.05 \pm 0.26 \pm 0.02)% and BR(\text{BR}(D_s^+ \to K^+ K^+ \pi^-)/BR()/\text{BR}(D_s^+ \to K^+ K^- \pi^+)=(0.52±0.17±0.11)) = (0.52\pm 0.17\pm 0.11)% where the first errors are statistical and the second are systematic. Expressed as 90% confidence levels (CL), we find <0.46< 0.46 % and <0.78 < 0.78% respectively. This is the first successful use of genetic programming in a high energy physics data analysis.Comment: 10 page

    Measurement of the D+ and Ds+ decays into K+K-K+

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    We present the first clear observation of the doubly Cabibbo suppressed decay D+ --> K-K+K+ and the first observation of the singly Cabibbo suppressed decay Ds+ --> K-K+K+. These signals have been obtained by analyzing the high statistics sample of photoproduced charm particles of the FOCUS(E831) experiment at Fermilab. We measure the following relative branching ratios: Gamma(D+ --> K-K+K+)/Gamma(D+ --> K-pi+pi+) = (9.49 +/- 2.17(statistical) +/- 0.22(systematic))x10^-4 and Gamma(Ds+ --> K-K+K+)/Gamma(Ds+ --> K-K+pi+) = (8.95 +/- 2.12(statistical) +2.24(syst.) -2.31(syst.))x10^-3.Comment: 10 pages, 8 figure

    A Non-parametric Approach to the D+ to K*0bar mu+ nu Form Factors

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    Using a large sample of D+ -> K- pi+ mu+ nu decays collected by the FOCUS photoproduction experiment at Fermilab, we present the first measurements of the helicity basis form factors free from the assumption of spectroscopic pole dominance. We also present the first information on the form factor that controls the s-wave interference discussed in a previous paper by the FOCUS collaboration. We find reasonable agreement with the usual assumption of spectroscopic pole dominance and measured form factor ratios.Comment: 14 pages, 5 figures, and 2 tables. We updated the previous version by changing some words, removing one plot, and adding two tables. These changes are mostly stylisti

    New Measurements of the D+ to K* mu nu Form Factor Ratios

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    Using a large sample of D+ to K- pi+ mu+ nu decays collected by the FOCUS photoproduction experiment at Fermilab, we present new measurements of two semileptonic form factor ratios: rv and r2. We find rv = 1.504 \pm 0.057 \pm 0.039 and r2 = 0.875 \pm 0.049 \pm 0.064. Our form factor results include the effects of the s-wave interference discussed in a previous paper.Comment: 12 pages, 5 figure

    Study of the D^0 \to pi^-pi^+pi^-pi^+ decay

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    Using data from the FOCUS (E831) experiment at Fermilab, we present new measurements for the Cabibbo-suppressed decay mode D0ππ+ππ+D^0 \to \pi^-\pi^+\pi^-\pi^+. We measure the branching ratio Γ(D0π+ππ+π)/Γ(D0Kπ+ππ+)=0.0914±0.0018±0.0022\Gamma(D^0 \to\pi^+\pi^- \pi^+\pi^-)/\Gamma(D^0 \to K^-\pi^+\pi^-\pi^+) = 0.0914 \pm 0.0018 \pm 0.0022. An amplitude analysis has been performed, a first for this channel, in order to determine the resonant substructure of this decay mode. The dominant component is the decay D0a1(1260)+πD^0 \to a_1(1260)^+ \pi^-, accounting for 60% of the decay rate. The second most dominant contribution comes from the decay D0ρ(770)0ρ(770)0D^0 \to \rho(770)^0\rho(770)^0, with a fraction of 25%. We also study the a1(1260)a_1(1260) line shape and resonant substructure. Using the helicity formalism for the angular distribution of the decay D0ρ(770)0ρ(770)0D^0 \to \rho(770)^0\rho(770)^0, we measure a longitudinal polarization of PL=(71±4±2)P_L = (71 \pm 4\pm 2)%.Comment: 38 pages, 8 figures. accepted for publication in Physical Review

    Measurements of Ξc+\Xi_c^{+} Branching Ratios

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    Using data collected by the fixed target Fermilab experiment FOCUS, we measure the branching ratios of the Cabibbo favored decays Ξc+Σ+Kπ+\Xi_c^+ \to \Sigma^+K^-\pi^+, Ξc+Σ+Kˉ(892)0\Xi_c^+ \to \Sigma^+ \bar{K}^{*}(892)^0, and Ξc+Λ0Kπ+π+\Xi_c^+ \to \Lambda^0K^-\pi^+\pi^+ relative to Ξc+Ξπ+π+\Xi_c^+ \to \Xi^-\pi^+\pi^+ to be 0.91±0.11±0.040.91\pm0.11\pm0.04, 0.78±0.16±0.060.78\pm0.16\pm0.06, and 0.28±0.06±0.060.28\pm0.06\pm0.06, respectively. We report the first observation of the Cabibbo suppressed decay Ξc+Σ+K+K\Xi_c^+ \to \Sigma^+K^+K^- and we measure the branching ratio relative to Ξc+Σ+Kπ+\Xi_c^+ \to \Sigma^+K^-\pi^+ to be 0.16±0.06±0.010.16\pm0.06\pm0.01. We also set 90% confidence level upper limits for Ξc+Σ+ϕ\Xi_c^+ \to \Sigma^+ \phi and Ξc+Ξ(1690)0(Σ+K)K+\Xi_c^+ \to \Xi^*(1690)^0(\Sigma^+ K^-) K^+ relative to Ξc+Σ+Kπ+\Xi_c^+ \to \Sigma^+K^-\pi^+ to be 0.12 and 0.05, respectively. We find an indication of the decays Ξc+ΩK+π+\Xi_c^+ \to \Omega^-K^{+}\pi^+ and Ξc+Σ(1385)+Kˉ0\Xi_c^+ \to \Sigma^{*}(1385)^+ \bar{K}^0 and set 90% confidence level upper limits for the branching ratios with respect to Ξc+Ξπ+π+\Xi_c^+ \to \Xi^-\pi^+\pi^+ to be 0.12 and 1.72, respectively. Finally, we determine the 90% C.L. upper limit for the resonant contribution Ξc+Ξ(1530)0π+\Xi_c^+ \to \Xi^{*}(1530)^0 \pi^+ relative to Ξc+Ξπ+π+\Xi_c^+ \to \Xi^-\pi^+\pi^+ to be 0.10.Comment: 14 pages, 8 figure
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