3,327 research outputs found

    Blurred Lines Between Competition and Parasitism

    Get PDF
    Accurately describing the ecological relationships between species is more than mere semantics-doing so has profound practical and applied implications, not the least of which is that inaccurate descriptions can lead to fundamentally incorrect predicted outcomes of community composition and functioning. Accurate ecological classifications are particularly important in the context of global change, where species interactions can change rapidly following shifts in species composition. Here, we argue that many common ecological interactions-particularly competition and parasitism-can be easily confused and that we often lack empirical evidence for the full reciprocal interaction among species. To make our case and to propose a theoretical framework for addressing this problem, we use the interactions between lianas and trees, whose outcomes have myriad implications for the ecology and conservation of tropical forests (e.g., Schnitzer et al. 2015)

    Left-right symmetric model with μτ\mu\leftrightarrow\tau symmetry

    Full text link
    We analyze the leptonic sector in the left-right symmetric model dressed with a (Z2)3(Z_{2})^{3} discrete symmetry which realizes, after weak spontaneous breaking, a small broken \mu\lra\tau symmetry that is suggested to explain observable neutrino oscillation data. \mu\lra\tau symmetry is broken at tree level in the effective neutrino mass matrix due to the mass difference m~τm~μ\widetilde{m}_{\tau}\neq \widetilde{m}_{\mu} in the diagonal Dirac mass terms, whereas all lepton mixings arise from a Majorana mass matrix. In the limit of a small breaking we determined θ13\theta_{13}, and the deviation from the maximal value of θATM\theta_{ATM}, in terms of the light neutrino hierarchy scale, m3m_{3}, and a single free parameter hsh_{s} of the model.Comment: 9 pages, 4 figures. Title changed and we have added one new section: CP phase contribution. Minor corrections and references updated. Published versio

    Supergeometry of Three Dimensional Black Holes

    Get PDF
    We show how the supersymmetric properties of three dimensional black holes can be obtained algebraically. The black hole solutions are constructed as quotients of the supergroup OSp(12;R)OSp(1|\,2;R) by a discrete subgroup of its isometry supergroup. The generators of the action of the isometry supergroup which commute with these identifications are found. These yield the supersymmetries for the black hole as found in recent studies as well as the usual geometric isometries. It is also shown that in the limit of vanishing cosmological constant, the black hole vacuum becomes a null orbifold, a solution previously discussed in the context of string theory.Comment: 12 pages, harvmac, discussion of rotating black hole added, some minor corrections, reference adde

    Enhancement of flavour properties in wines using sequential inoculations of non-Saccharomyces (Hansenula and Torulaspora) and Saccharomyces yeast

    Get PDF
    In order to produce wines with greater complexity of aroma and taste, fermentations were carried out by sequential inoculation of non-Saccharomyces (Hansenula anomala and Torulaspora delbrueckii) and Saccharomyces cerevisiae yeasts in 'Airén' variety white grape musts. The wines made by sequential inoculation had a higher pH and higher levels of acetates, compounds that supply a fruity note. The wines inoculated with Hansenula anomala presented a lower concentration of lineal alcohols and thioalcohols, which are respectively responsible for herbaceous and cooked notes. The fermentations performed by sequential inoculation of Torulaspora delbrueckii and Saccharomyces cerevisiae produced wines with lower levels of volatile acidity, acetaldehyde and carbonyl compounds. In preference tasting, the 'Airén' wines obtained by co-inoculation with the species Hansenula anomala scored highest for their sensory qualities and were particularly appreciated for their floral and/or fruity notes

    Influencia del sedentarismo en las desviaciones raquídeas de la población escolar de Léon

    Full text link
    Nuestra investigación trata de evaluar los hábitos sedentarios, en los escolares de 10 y 14 años de una zona de León, y su influencia en las desviaciones raquídeas. Para la obtención de los hábitos nos basamos en el tets de Medoza, R. también se realizó una evaluación física de los niños para observar las desviaciones raquídeas. En el tratamiento de la información se utilizó el análisis de la varianza univariante y multivariante, además del análisis de componentes principales y análisis discriminante. Llegando a la conclusión, respecto al tiempo de televisión que el día de la semana que más tiempo dedican los niños a ver la televisión es discrimante de los escolares que tienen desviación raquídea

    Global gravitational instability of FLRW backgrounds - interpreting the dark sectors

    Get PDF
    The standard model of cosmology is based on homogeneous-isotropic solutions of Einstein's equations. These solutions are known to be gravitationally unstable to local inhomogeneous perturbations, commonly described as evolving on a background given by the same solutions. In this picture, the FLRW backgrounds are taken to describe the average over inhomogeneous perturbations for all times. We study in the present article the (in)stability of FLRW dust backgrounds within a class of averaged inhomogeneous cosmologies. We examine the phase portraits of the latter, discuss their fixed points and orbital structure and provide detailed illustrations. We show that FLRW cosmologies are unstable in some relevant cases: averaged models are driven away from them through structure formation and accelerated expansion. We find support for the proposal that the dark components of the FLRW framework may be associated to these instability sectors. Our conclusion is that FLRW cosmologies have to be considered critically as for their role to serve as reliable models for the physical background.Comment: 15 pages, 13 figures, 1 table. Matches published version in CQ

    The thermodynamic evolution of the cosmological event horizon

    Full text link
    By manipulating the integral expression for the proper radius ReR_e of the cosmological event horizon (CEH) in a Friedmann-Robertson-Walker (FRW) universe, we obtain an analytical expression for the change \dd R_e in response to a uniform fluctuation \dd\rho in the average cosmic background density ρ\rho. We stipulate that the fluctuation arises within a vanishing interval of proper time, during which the CEH is approximately stationary, and evolves subsequently such that \dd\rho/\rho is constant. The respective variations 2\pi R_e \dd R_e and \dd E_e in the horizon entropy SeS_e and enclosed energy EeE_e should be therefore related through the cosmological Clausius relation. In that manner we find that the temperature TeT_e of the CEH at an arbitrary time in a flat FRW universe is Ee/SeE_e/S_e, which recovers asymptotically the usual static de Sitter temperature. Furthermore, it is proven that during radiation-dominance and in late times the CEH conforms to the fully dynamical First Law T_e \drv S_e = P\drv V_e - \drv E_e, where VeV_e is the enclosed volume and PP is the average cosmic pressure.Comment: 6 page

    Validity of the Generalized Second Law of Thermodynamics of the Universe Bounded by the Event Horizon in Brane Scenario

    Full text link
    In this paper, we examine the validity of the generalized second law of thermodynamics (GSLT) of the universe bounded by the event horizon in brane-world gravity. Here we consider homogeneous and isotropic model of the universe filled with perfect fluid in one case and in another case holographic dark energy model of the universe has been considered. The conclusions are presented point wise.Comment: 8 pages, the paper has been accepted in EPJC for publication. Conclusion has been modified an some references have been adde
    corecore