65 research outputs found

    Infinite-randomness critical point in the two-dimensional disordered contact process

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    We study the nonequilibrium phase transition in the two-dimensional contact process on a randomly diluted lattice by means of large-scale Monte-Carlo simulations for times up to 101010^{10} and system sizes up to 8000Ă—80008000 \times 8000 sites. Our data provide strong evidence for the transition being controlled by an exotic infinite-randomness critical point with activated (exponential) dynamical scaling. We calculate the critical exponents of the transition and find them to be universal, i.e., independent of disorder strength. The Griffiths region between the clean and the dirty critical points exhibits power-law dynamical scaling with continuously varying exponents. We discuss the generality of our findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder. Our results are of importance beyond absorbing state transitions because according to a strong-disorder renormalization group analysis, our transition belongs to the universality class of the two-dimensional random transverse-field Ising model.Comment: 13 pages, 12 eps figures, final version as publishe

    Action in culture : act I of the presidential primary campaign in the U.S., April to December, 2015

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    This article offers a thick description of the United States during the first nine months of the 2016 presidential election competition. It argues that this competition is organized in a theatrical way, and that this period, from April to December 2015, represents act one of the drama. It argues that performances in act one contribute to setting the cultural and interpretive conditions in which citizens will enter and act back on the drama in its subsequent acts, in state primaries and caucuses, and in the general election in November 2016. Building on the works of Roland Barthes and Clifford Geertz, the article gives a structural, or semiotic, interpretation of the dominant symbols and discourses operating in the dramatic field, and using Alexander’s cultural pragmatics, it identifies and analyzes key performances given by candidates Clinton and Trump, which crystalized particular meaning formations and lent the proceedings a sense of dynamism and flow. The article demonstrates how analyzing performances in a manner consistent with cultural pragmatic theory contributes to research on electoral politics, political authority, and legitimation processes

    Maerl grounds : habitats of high biodiversity in European seas

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    The BIOMAERL programme is a 3-year collaborative programme between laboratories in UK, Spain, France and Malta which began in February 1996. Its main plans are described in the workplan. A full inventory of the biological composition (biodiversity) of maerl bed assemblages in these regions therefore has yet to be completed, but progress is outlined below.peer-reviewe

    Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe3O4 nanoparticles for biomedical applications

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    In this work, the effect of nanoparticle confinement on the magnetic relaxation of iron oxide (Fe 3 O 4 ) nanoparticles (NP) was investigated by measuring the hyperthermia heating behavior in high frequency alternating magnetic field. Three different Fe 3 O 4 nanoparticle systems having distinct nanoparticle configurations were studied in terms of magnetic hyperthermia heating rate and DC magnetization. All magnetic nanoparticle (MNP) systems were constructed using equivalent~10 nm diameter NP that were structured differently in terms of configuration, physical confinement, and interparticle spacing. The spatial confinement was achieved by embedding the Fe 3 O 4 nanoparticles in the matrices of the polystyrene spheres of 100 nm, while the unconfined was the free Fe 3 O 4 nanoparticles well-dispersed in the liquid via PAA surface coating. Assuming the identical core MNPs in each system, the heating behavior was analyzed in terms of particle freedom (or confinement), interparticle spacing, and magnetic coupling (or dipole-dipole interaction). DC magnetization data were correlated to the heating behavior with different material properties. Analysis of DC magnetization measurements showed deviation from classical Langevin behavior near saturation due to dipole interaction modification of the MNPs resulting in a high magnetic anisotropy. It was found that the Specific Absorption Rate (SAR) of the unconfined nanoparticle systems were significantly higher than those of confined (the MNPs embedded in the polystyrene matrix). This increase of SAR was found to be attributable to high NĂ©el relaxation rate and hysteresis loss of the unconfined MNPs. It was also found that the dipole-dipole interactions can significantly reduce the global magnetic response of the MNPs and thereby decrease the SAR of the nanoparticle systems

    Visualizing Tree Structures in Genetic Programming

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    This paper presents methods to visualize the structure of trees that occur in genetic programming. These methods allow for the inspection of structure of entire trees even though several thousands of nodes may be involved. The methods also scale to allow for the inspection of structure for entire populations and for complete trials even though millions of nodes may be involved. Examples are given that demonstrate how this new way of “seeing” can afford a potentially rich way of understanding dynamics that underpin genetic programming. The examples indicate further studies that might be enabled by visualizing structure at these scales.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45620/1/10710_2005_Article_7621.pd

    Every Other Row Furrow Irrigation Trial

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    Abstract Silage corn yields are limited by irrigation effectiveness in the Central Valley of California. This experiment was conducted to determine if silage yield would suffer after altering irrigation methods and timing. The effects of irrigation method and timing were tested on field corn [Zea mays (DKC 67-86)]. The study was carried out in Denair, California on a Whitney Rocklin sandy loam. Silage tonnage, grain yield, and plant height were compared across four treatments with three repetitions of each treatment. The treatments were every other row, the grower’s standard practice, deficit, and a control. The experiment showed that every other row irrigation does not significantly hurt silage corn yields when compared to the control, with every row irrigated on the same schedule as every other row. Grain yield showed the most variation among the treatments with the control yielding an average of 225.71 bushels per acre, deficit yielding an average of 140.04 bushels per acre, and the other two treatments ranging in between. Overall, the experiment showed that more irrigations results in higher yielding corn, and every other row irrigation could be utilized to speed up the irrigation schedule. Additional Index Words: Irrigation, furrow irrigation, every other row irrigation, silage corn, utilizing dairy lagoon water, estimating grain yield, Zea mays (DKC 67-86)

    Infinite-Randomness Critical Point in the Two-Dimensional Disordered Contact Process

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    We study the nonequilibrium phase transition in the two-dimensional contact process on a randomly diluted lattice by means of large-scale Monte Carlo simulations for times up to 1010 and system sizes up to 8000Ă—8000 sites. Our data provide strong evidence for the transition being controlled by an exotic infinite-randomness critical point with activated (exponential) dynamical scaling. We calculate the critical exponents of the transition and find them to be universal, i.e., independent of disorder strength. The Griffiths region between the clean and the dirty critical points exhibits power-law dynamical scaling with continuously varying exponents. We discuss the generality of our findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder. Our results are of importance beyond absorbing state transitions because, according to a strong-disorder renormalization group analysis, our transition belongs to the universality class of the two-dimensional random transverse-field Ising model
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