2,351 research outputs found
About the coordinate time for photons in Lifshitz Space-times
In this paper we studied the behavior of radial photons from the point of
view of the coordinate time in (asymptotically) Lifshitz space-times, and we
found a generalization to the result reported in previous works by Cruz et. al.
[Eur. Phys. J. C {\bf 73}, 7 (2013)], Olivares et. al. [Astrophys. Space Sci.
{\bf 347}, 83-89 (2013)], and Olivares et. al. [arXiv: 1306.5285]. We
demonstrate that all asymptotically Lifshitz space-times characterized by a
lapse funcion which tends to one when , present the
same behavior, in the sense that an external observer will see that photons
arrive at spatial infinity in a finite coordinate time. Also, we show that
radial photons in the proper system cannot determine the presence of the black
hole in the region , because the proper time results to be
independent of the lapse function .Comment: 5 pages, 4 figures, accepted for publication on EPJ
Large lianas as hyperdynamic elements of the tropical forest canopy
Lianas (woody vines) are an important component of lowland tropical forests.
We report large liana and tree inventory and dynamics data from Amazonia over periods
of up to 24 years, making this the longest geographically extensive study of liana ecology
to date. We use these results to address basic questions about the ecology of large lianas
in mature forests and their interactions with trees. In one intensively studied site we find
that large lianas (≥10 cm diameter) represent ,5% of liana stems, but 80% of biomass of
well-lit upper canopy lianas. Across sites, large lianas and large trees are both most successful
in terms of structural importance in richer soil forests, but large liana success may
be controlled more by the availability of large tree supports rather than directly by soil
conditions. Long-term annual turnover rates of large lianas are 5–8%, three times those of
trees. Lianas are implicated in large tree mortality: liana-infested large trees are three times
more likely to die than liana-free large trees, and large lianas are involved in the death of
at least 30% of tree basal area. Thus large lianas are a much more dynamic component of
Amazon forests than are canopy trees, and they play a much more significant functional
role than their structural contribution suggests
New universality class for the three-dimensional XY model with correlated impurities: Application to He in aerogels
Encouraged by experiments on He in aerogels, we confine planar spins in
the pores of simulated aerogels (diffusion limited cluster-cluster aggregation)
in order to study the effect of quenched disorder on the critical behavior of
the three-dimensional XY model. Monte Carlo simulations and finite-size scaling
are used to determine critical couplings and exponents. In agreement with
experiments, clear evidence of change in the thermal critical exponents
and is found at nonzero volume fractions of impurities. These changes
are explained in terms of {\it hidden} long-range correlations within disorder
distributions.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
SPRAY CONE ANGLES GENERATED BY A DUAL CENTRIFUGAL INJECTOR
A dual pressure swirl injector is characterized by two independent concentric chambers which can provide independent rotational levels to a single liquid or two different liquids. This paper compares theoretical, semi-empirical and experimental results concerning the spray cone angles formed by injection of water, ethanol and biodiesel through a dual pressure swirl injector. Data are obtained for injection of the same liquid through the primary and secondary chambers and for injection of ethanol in the primary chamber and biodiesel through the secondary chamber of the injector. Experimental data are obtained using photographic techniques and are analyzed by an image processing software developed in Matlab language
La nueva justicia tributaria en Chile: Reforma a los Tribunales Tributarios.
59 p.El primer capitulo aborda los conceptos básicos para comprender la composición de la actual justicia tributaria. Señalando los conceptos básicos que la componen, como la estructura de conocimiento de materias tributarias por los tribunales de Justicia.
El capitulo segundo, trata la actual situación de lo contencioso administrativo en Chile, además de señalar la actual situación de los tribunales tributarios y un análisis de constitucionalidad de los mismos, finalizando con una enumeración de los actuales procedimientos tributarios de primera instancia.
En el capitulo tercero, trataremos la composición de los tribunales tributarios en el derecho comparado, mas especÃficamente en Argentina, España y Venezuela.
Finalmente, en el capitulo cuarto explicamos el origen del proyecto de ley que fortalece y perfecciona la justicia tributaria, señalando los principales elementos que, nos parece, debieran ser modificados, a fin de dar curso a la tan esperada reforma de una manera que nos permita evitar futuros inconvenientes
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