3,327 research outputs found
Blurred Lines Between Competition and Parasitism
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 symmetry
We analyze the leptonic sector in the left-right symmetric model dressed with
a 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
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 , and the deviation from
the maximal value of , in terms of the light neutrino hierarchy
scale, , and a single free parameter 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
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 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
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
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
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
By manipulating the integral expression for the proper radius 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 . 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 and
enclosed energy should be therefore related through the cosmological
Clausius relation. In that manner we find that the temperature of the CEH
at an arbitrary time in a flat FRW universe is , 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
is the enclosed volume and 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
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
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