8,034 research outputs found

    The scalar glueball spectrum

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    We discuss scenarios for scalar glueballs using arguments based on sum rules, spectral decomposition, the 1Nc\frac{1}{N_c} approximation, the scales of the strong interaction and the topology of the flux tubes. We analyze the phenomenological support of those scenarios and their observational implications. Our investigations hint a rich low lying glueball spectrum.Comment: 11 pages: New title, figure, table and a more detailed comparison with experiment

    Production of embryos from microspore cultures of Portuguese tronchuda cabbage landraces

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    Twelve accessions of tronchuda cabbage landraces were tested for their ability to produce embryos through microspore culture in NLN-13 medium. A sample from all the isolations was stained with DAPI for determination of microspore developmental stage. The relationship between the microspore developmental stage and the production of microspore-derived embryos was evaluated. Embryos were obtained from all the accessions. Considerable variation was observed between isolations with different developmental stage of microspores, accessions and plants within the same accession. The best embryogenic responses occurred in microspore populations with approximately 10 to 89% of binucleate pollen. The highest embryo yield was obtained with one of the ‘Couve de Valhascos’ accessions (0.41 embryos / 1 000 microspores) and the lowest yields with the accessions of ‘Couve Portuguesa’ (less than 0.07 embryos / 1 000 microspores)

    Classical Tensors and Quantum Entanglement II: Mixed States

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    Invariant operator-valued tensor fields on Lie groups are considered. These define classical tensor fields on Lie groups by evaluating them on a quantum state. This particular construction, applied on the local unitary group U(n)xU(n), may establish a method for the identification of entanglement monotone candidates by deriving invariant functions from tensors being by construction invariant under local unitary transformations. In particular, for n=2, we recover the purity and a concurrence related function (Wootters 1998) as a sum of inner products of symmetric and anti-symmetric parts of the considered tensor fields. Moreover, we identify a distinguished entanglement monotone candidate by using a non-linear realization of the Lie algebra of SU(2)xSU(2). The functional dependence between the latter quantity and the concurrence is illustrated for a subclass of mixed states parametrized by two variables.Comment: 23 pages, 4 figure

    Insights on KP4 Killer Toxin-like Proteins of Fusarium Species in Interspecific Interactions

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    KP4 killer toxins are secreted proteins that inhibit cell growth and induce cell death in target organisms. In Fusarium graminearum, KP4-like (KP4L) proteins contribute to fungal virulence in wheat seedling rot and are expressed during Fusarium head blight development. However, fungal KP4L proteins are also hypothesized to support fungal antagonism by permeabilizing cell walls of competing fungi to enable penetration of toxic compounds. Here, we report the differential expression patterns of F. graminearum KP4L genes (Fgkp4l-1, -2, -3 and -4) in a competitive interaction, using Trichoderma gamsii as the antagonist. The results from dual cultures indicate that Fgkp4l-3 and Fgkp4l-4 could participate in the recognition at the distance of the antagonist, while all Fgkp4l genes were highly activated in the pathogen during the physical interaction of both fungi. Only Fgkp4l-4 was up-regulated during the interaction with T. gamsii in wheat spikes. This suggests the KP4L proteins could participate in supporting F. graminearum interspecific interactions, even in living plant tissues. The distribution of KP4L orthologous within the genus Fusarium revealed they are more represented in species with broad host-plant range than in host-specific species. Phylogeny inferred provides evidence that KP4L genes evolved through gene duplications, gene loss and sequence diversification in the genus Fusarium

    A participatory public art process in Almada: Agents and values

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    The impact of public art on the territory has an undeniable cultural dimension since it creates new sensorial and visual agents, with potential social interactivity. In this paper we present and discuss a Portuguese case-study of participated public art, developed for the Caparica Civic Centre (Almada, Portugal) by a team that includes artists (sculptors), anthropologists, local associations and inhabitants. The territory and the community were the main pillars for the conception of a three piece monument, built in a multicultural neighborhood, through a progressive and interactive working methodology, between 2011 and 2013.info:eu-repo/semantics/submittedVersio

    Class of dilute granular Couette flows with uniform heat flux

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    In a recent paper [F. Vega Reyes et al., Phys. Rev. Lett. 104, 028001 (2010)] we presented a preliminary description of a special class of steady Couette flows in dilute granular gases. In all flows of this class the viscous heating is exactly balanced by inelastic cooling. This yields a uniform heat flux and a linear relationship between the local temperature and flow velocity. The class (referred to as the LTu class) includes the Fourier flow of ordinary gases and the simple shear flow of granular gases as special cases. In the present paper we provide further support for this class of Couette flows by following four different routes, two of them being theoretical (Grad's moment method of the Boltzmann equation and exact solution of a kinetic model) and the other two being computational (molecular dynamics and Monte Carlo simulations of the Boltzmann equation). Comparison between theory and simulations shows a very good agreement for the non-Newtonian rheological properties, even for quite strong inelasticity, and a good agreement for the heat flux coefficients in the case of Grad's method, the agreement being only qualitative in the case of the kinetic model.Comment: 15 pages, 10 figures; v2: change of title plus some other minor change

    Dynamically Generated Resonances in the Chiral Unitary Approach to Meson Baryon Interaction

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    In this talk we report on the use of a chiral unitary approach for the interaction of the octets of meson and baryon and the octet of mesons with the decuplet of baryons. Two octets of Jπ=1/2−J^{\pi}=1/2^- baryon states and a singlet are generated dynamically in the first case, resulting in the case of strangeness S=−1S=-1 in two poles of the scattering matrix close to the nominal Λ(1405)\Lambda(1405) resonance. In the second case many resonances are also generated, among them an exotic baryon with S=1 corresponding to a ΔK\Delta K resonance. We make suggestions of experiments which could show evidence for the existence of these states.Comment: Talk at the MENU04 Symposium, Beijing, September 200

    Segregation of an intruder in a heated granular dense gas

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    A recent segregation criterion [V. Garz\'o, Phys. Rev. E \textbf{78}, 020301(R) (2008)] based on the thermal diffusion factor Λ\Lambda of an intruder in a heated granular gas described by the inelastic Enskog equation is revisited. The sign of Λ\Lambda provides a criterion for the transition between the Brazil-nut effect (BNE) and the reverse Brazil-nut effect (RBNE). The present theory incorporates two extra ingredients not accounted for by the previous theoretical attempt. First, the theory is based upon the second Sonine approximation to the transport coefficients of the mass flux of intruder. Second, the dependence of the temperature ratio (intruder temperature over that of the host granular gas) on the solid volume fraction is taken into account in the first and second Sonine approximations. In order to check the accuracy of the Sonine approximation considered, the Enskog equation is also numerically solved by means of the direct simulation Monte Carlo (DSMC) method to get the kinetic diffusion coefficient D0D_0. The comparison between theory and simulation shows that the second Sonine approximation to D0D_0 yields an improvement over the first Sonine approximation when the intruder is lighter than the gas particles in the range of large inelasticity. With respect to the form of the phase diagrams for the BNE/RBNE transition, the kinetic theory results for the factor Λ\Lambda indicate that while the form of these diagrams depends sensitively on the order of the Sonine approximation considered when gravity is absent, no significant differences between both Sonine solutions appear in the opposite limit (gravity dominates the thermal gradient). In the former case (no gravity), the first Sonine approximation overestimates both the RBNE region and the influence of dissipation on thermal diffusion segregation.Comment: 9 figures; to be published in Phys. Rev.
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