284 research outputs found

    Spatial Particle Condensation for an Exclusion Process on a Ring

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    We study the stationary state of a simple exclusion process on a ring which was recently introduced by Arndt {\it et al} [J. Phys. A {\bf 31} (1998) L45;cond-mat/9809123]. This model exhibits spatial condensation of particles. It has been argued that the model has a phase transition from a ``mixed phase'' to a ``disordered phase''. However, in this paper exact calculations are presented which, we believe, show that in the framework of a grand canonical ensemble there is no such phase transition. An analysis of the fluctuations in the particle density strongly suggests that the same result also holds for the canonical ensemble.Comment: 20 pages, 4 figure

    Bioavailability of Glucoraphanin and Sulforaphane From High-Glucoraphanin Broccoli

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    Scope: Broccoli accumulates 4-methylsulphinylbutyl glucosinolate (glucoraphanin) which is hydrolyzed to the isothiocyanate sulforaphane. Through the introgression of novel alleles of the Myb28 transcription factor from Brassica villosa, broccoli genotypes have been developed that have enhanced levels of glucoraphanin. This study sought to quantify the exposure of human tissues to glucoraphanin and sulforaphane following consumption of broccoli with contrasting Myb28 genotypes. Methods and results: Ten participants were recruited into a three-phase, double-blinded, randomized crossover trial (NCT02300324), with each phase comprising consumption of 300 ml of a soup made from broccoli of one of three Myb28 genotypes (Myb28B/B, Myb28B/V, Myb28V/V). Plant myrosinases were intentionally denatured during soup manufacture. Three-fold and five-fold higher levels of sulforaphane occurred in the circulation following consumption of Myb28V/B and Myb28V/V broccoli soups, respectively. The percentage of sulforaphane excreted in 24 h relative to the amount of glucoraphanin consumed varied amongst volunteers from 2% to 15%, but did not depend on the broccoli genotype. Conclusion: This is the first study to report the bioavailability of glucoraphanin and sulforaphane from soups made with novel broccoli varieties. The presence of one or two Myb28V alleles results in enhanced delivery of sulforaphane to the systemic circulation

    The q-harmonic oscillator and an analog of the Charlier polynomials

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    A model of a q-harmonic oscillator based on q-Charlier polynomials of Al-Salam and Carlitz is discussed. Simple explicit realization of q-creation and q-annihilation operators, q-coherent states and an analog of the Fourier transformation are found. A connection of the kernel of this transform with biorthogonal rational functions is observed

    The Bivariate Rogers-Szeg\"{o} Polynomials

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    We present an operator approach to deriving Mehler's formula and the Rogers formula for the bivariate Rogers-Szeg\"{o} polynomials hn(x,yq)h_n(x,y|q). The proof of Mehler's formula can be considered as a new approach to the nonsymmetric Poisson kernel formula for the continuous big qq-Hermite polynomials Hn(x;aq)H_n(x;a|q) due to Askey, Rahman and Suslov. Mehler's formula for hn(x,yq)h_n(x,y|q) involves a 3ϕ2{}_3\phi_2 sum and the Rogers formula involves a 2ϕ1{}_2\phi_1 sum. The proofs of these results are based on parameter augmentation with respect to the qq-exponential operator and the homogeneous qq-shift operator in two variables. By extending recent results on the Rogers-Szeg\"{o} polynomials hn(xq)h_n(x|q) due to Hou, Lascoux and Mu, we obtain another Rogers-type formula for hn(x,yq)h_n(x,y|q). Finally, we give a change of base formula for Hn(x;aq)H_n(x;a|q) which can be used to evaluate some integrals by using the Askey-Wilson integral.Comment: 16 pages, revised version, to appear in J. Phys. A: Math. Theo

    The impact of Stieltjes' work on continued fractions and orthogonal polynomials

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    Stieltjes' work on continued fractions and the orthogonal polynomials related to continued fraction expansions is summarized and an attempt is made to describe the influence of Stieltjes' ideas and work in research done after his death, with an emphasis on the theory of orthogonal polynomials

    TRY plant trait database - enhanced coverage and open access

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    Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

    An analysis of the Human Development Report 2011 : sustainability and equity : a better future for all

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    The Human Development Report 2007/2008 about climate change and development made bold arguments concerning human rights and justice for the poor and for disadvantaged populations. However, its policy proposals were not as bold, looking very similar to those of the World Bank's World Development Report 2010. In this article we investigate in which direction the thinking on environment and sustainability by UNDP's Human Development Report Office has evolved since the HDR 2007/2008. A detailed frame and lexical analysis of the HDR 2011 on Sustainability and Equity shows a markedly technocratic direction, largely apolitical and insensitive to human rights issues and justice, giving a diluted successor to the HDR 2007/2008 and now close in perspective to the World Bank. This direction, as well as the little attention to the socio-economic and political barriers to sustainability and to climate change impacts we find in the HDR 2011, has consequences for the poorest sectors of South Africa's society

    Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

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    The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
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