731 research outputs found

    Neuro-Fuzzy Based Hybrid Model for Web Usage Mining

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    AbstractWeb Usage mining consists of three main steps: Pre-processing, Knowledge Discovery and Pattern Analysis. The information gained from the analysis can then be used by the website administrators for efficient administration and personalization of their websites and thus the specific needs of specific communities of users can be fulfilled and profit can be increased. Also, Web Usage Mining uncovers the hidden patterns underlying the Web Log Data. These patterns represent user browsing behaviours which can be employed in detecting deviations in user browsing behaviour in web based banking and other applications where data privacy and security is of utmost importance. Proposed work pre-process, discovers and analyses the Web Log Data of Dr. T.M.A.PAI polytechnic website. A neuro-fuzzy based hybrid model is employed for Knowledge Discovery from web logs

    Superconductivity behaviour of screen-printed LnBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB> (Ln=Eu,Y)films

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    Thick films of the high Tc superconducting oxides, LnBa2Cu3O7, Ln=Eu, Y, have been fabricated by screen printing on alumina and SrTiO3 substrates. Conditions for optimum superconductivity behaviour of the films have been established. Tconset varies from 90-94 K for all the films but zero resistance was observed only in a few cases

    Superconductivity studies on Tl-Th-Sr-Ca-Cu-O system

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    Superconductivity with a maximum Tc,zero of 58 K for x &gt; 0&#183;75 has been observed in a nominal starting composition, ThxTl2Sr2Ca2Cu3Oy. X-ray data show that the 1212 phase gets stabilized due to part substitution of Th at the Tl-site for x &#8805; 0&#183;25; however, Tc is low for x &lt; 0&#183;75

    Gene content evolution in the arthropods

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    Arthropods comprise the largest and most diverse phylum on Earth and play vital roles in nearly every ecosystem. Their diversity stems in part from variations on a conserved body plan, resulting from and recorded in adaptive changes in the genome. Dissection of the genomic record of sequence change enables broad questions regarding genome evolution to be addressed, even across hyper-diverse taxa within arthropods. Using 76 whole genome sequences representing 21 orders spanning more than 500 million years of arthropod evolution, we document changes in gene and protein domain content and provide temporal and phylogenetic context for interpreting these innovations. We identify many novel gene families that arose early in the evolution of arthropods and during the diversification of insects into modern orders. We reveal unexpected variation in patterns of DNA methylation across arthropods and examples of gene family and protein domain evolution coincident with the appearance of notable phenotypic and physiological adaptations such as flight, metamorphosis, sociality, and chemoperception. These analyses demonstrate how large-scale comparative genomics can provide broad new insights into the genotype to phenotype map and generate testable hypotheses about the evolution of animal diversity

    A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses

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    We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants

    System-Size Independence of Directed Flow Measured at the BNL Relativistic Heavy-Ion Collider

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    We measure directed flow (ν_1) for charged particles in Au+Au and Cu+Cu collisions at √S_(NN)=200 and 62.4 GeV, as a function of pseudorapidity (η), transverse momentum (p_t), and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all available model implementations, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to ν_1 in different collision systems, and investigate possible explanations for the observed sign change in ν_1(p_t)

    Enhanced strange baryon production in Au+Au collisions compared to p+p at sqrts = 200 GeV

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    We report on the observed differences in production rates of strange and multi-strange baryons in Au+Au collisions at sqrts = 200 GeV compared to pp interactions at the same energy. The strange baryon yields in Au+Au collisions, then scaled down by the number of participating nucleons, are enhanced relative to those measured in pp reactions. The enhancement observed increases with the strangeness content of the baryon, and increases for all strange baryons with collision centrality. The enhancement is qualitatively similar to that observed at lower collision energy sqrts =17.3 GeV. The previous observations are for the bulk production, while at intermediate pT, 1 < pT< 4 GeV/c, the strange baryons even exceed binary scaling from pp yields.Comment: 7 pages, 4 figures. Printed in PR

    Spin alignment measurements of the K0(892)K^{*0}(892) and ϕ(1020)\phi(1020) vector mesons at RHIC

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    We present the first spin alignment measurements for the K0(892)K^{*0}(892) and ϕ(1020)\phi(1020) vector mesons produced at mid-rapidity with transverse momenta up to 5 GeV/c at sNN\sqrt{s_{NN}} = 200 GeV at RHIC. The diagonal spin density matrix elements with respect to the reaction plane in Au+Au collisions are ρ00\rho_{00} = 0.32 ±\pm 0.04 (stat) ±\pm 0.09 (syst) for the K0K^{*0} (0.8<pT<5.00.8<p_T<5.0 GeV/c) and ρ00\rho_{00} = 0.34 ±\pm 0.02 (stat) ±\pm 0.03 (syst) for the ϕ\phi (0.4<pT<5.00.4<p_T<5.0 GeV/c), and are constant with transverse momentum and collision centrality. The data are consistent with the unpolarized expectation of 1/3 and thus no evidence is found for the transfer of the orbital angular momentum of the colliding system to the vector meson spins. Spin alignments for K0K^{*0} and ϕ\phi in Au+Au collisions were also measured with respect to the particle's production plane. The ϕ\phi result, ρ00\rho_{00} = 0.41 ±\pm 0.02 (stat) ±\pm 0.04 (syst), is consistent with that in p+p collisions, ρ00\rho_{00} = 0.39 ±\pm 0.03 (stat) ±\pm 0.06 (syst), also measured in this work. The measurements thus constrain the possible size of polarization phenomena in the production dynamics of vector mesons.Comment: 7 pages, 4 figures. fig.1 updated; one more reference added, one typo corrected, published in PRC.77.06190

    Measurements of ϕ\phi meson production in relativistic heavy-ion collisions at RHIC

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    We present results for the measurement of ϕ\phi meson production via its charged kaon decay channel ϕK+K\phi \to K^+K^- in Au+Au collisions at sNN=62.4\sqrt{s_{_{NN}}}=62.4, 130, and 200 GeV, and in p+pp+p and dd+Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV from the STAR experiment at the BNL Relativistic Heavy Ion Collider (RHIC). The midrapidity (y<0.5|y|<0.5) ϕ\phi meson transverse momentum (pTp_{T}) spectra in central Au+Au collisions are found to be well described by a single exponential distribution. On the other hand, the pTp_{T} spectra from p+pp+p, dd+Au and peripheral Au+Au collisions show power-law tails at intermediate and high pTp_{T} and are described better by Levy distributions. The constant ϕ/K\phi/K^- yield ratio vs beam species, collision centrality and colliding energy is in contradiction with expectations from models having kaon coalescence as the dominant mechanism for ϕ\phi production at RHIC. The Ω/ϕ\Omega/\phi yield ratio as a function of pTp_{T} is consistent with a model based on the recombination of thermal ss quarks up to pT4p_{T}\sim 4 GeV/cc, but disagrees at higher transverse momenta. The measured nuclear modification factor, RdAuR_{dAu}, for the ϕ\phi meson increases above unity at intermediate pTp_{T}, similar to that for pions and protons, while RAAR_{AA} is suppressed due to the energy loss effect in central Au+Au collisions. Number of constituent quark scaling of both RcpR_{cp} and v2v_{2} for the ϕ\phi meson with respect to other hadrons in Au+Au collisions at sNN\sqrt{s_{_{NN}}}=200 GeV at intermediate pTp_{T} is observed. These observations support quark coalescence as being the dominant mechanism of hadronization in the intermediate pTp_{T} region at RHIC.Comment: 22 pages, 21 figures, 4 table
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