268,918 research outputs found
DARA and DRRA option bounds from concurrently expiring options
In this paper we derive option bounds from concurrently expiring options assuming the representative investor has decreasing absolute {relative} risk aversion. We show that given the prices of the underlying stock and n concurrently expiring options, the DARA {DRRA} option bound is given by a representative investor who has piecewise constant absolute {relative} risk aversion. We also derive option bounds from concurrently expiring option prices assuming the representative investor has decreasing and bounded absolute {relative} risk aversion
Theory of electrical conductivities of ferrogels
Conductive organic polymers can be formulated with polymers that incorporate
fine dispersed metallic particles.
In this work, we present a general model for ferrogels which are chemically
cross-linked polymer networks swollen with a ferrofluid. Our aim is to study
the effect of the shape and/or material (conductivity) anisotropy on the
effective electrical conductivity of the ferrogel in the presence of an
external magnetic field. Our theory can reproduce the known results, and
provides a link between the particle property and orientation distribution and
the effective electrical conductivity. To this end, we find that material
(conductivity) anisotropies are more important to yield a high effective
electrical conductivity than shape anisotropies, while magnetic fields can
offer a correction.Comment: 15 pages, 2 figure
Neutrino oscillations in de Sitter space-time
We try to understand flavor oscillations and to develop the formulae for
describing neutrino oscillations in de Sitter space-time. First, the covariant
Dirac equation is investigated under the conformally flat coordinates of de
Sitter geometry. Then, we obtain the exact solutions of the Dirac equation and
indicate the explicit form of the phase of wave function. Next, the concise
formulae for calculating the neutrino oscillation probabilities in de Sitter
space-time are given. Finally, The difference between our formulae and the
standard result in Minkowski space-time is pointed out.Comment: 13 pages, no figure
Open-closed field algebras
We introduce the notions of open-closed field algebra and open-closed field
algebra over a vertex operator algebra V. In the case that V satisfies certain
finiteness and reductivity conditions, we show that an open-closed field
algebra over V canonically gives an algebra over a \C-extension of the
Swiss-cheese partial operad. We also give a tensor categorical formulation and
categorical constructions of open-closed field algebras over V.Comment: 55 pages, largely revised, an old subsection is deleted, a few
references are adde
Whither China? Reform and economic integration among Chinese regions
This article has been made available through the Brunel Open Access Publishing Fund.This paper investigates the changing nature of economic integration in China. Specifically, we consider business-cycle synchronization (correlation of demand and supply shocks) among Chinese provinces during the period 1955-2007. We nd that the symmetry of supply shocks has declined after the liberalization initiated in 1978. In contrast, the correlation of demand shocks has increased during the same period. We then seek to explain these correlations by relating them to factors that proxy for interprovincial trade and vulnerability of regions to idiosyncratic shocks. Interprovincial trade and similarity in factor endowments tend to make shocks more symmetric. Surprisingly, foreign trade and inward FDI have little effect on the symmetry of shocks
Microstructure and mechanical properties of an Mg-3Zn- o.5Zr-5HA nanocomposite processed by ECAE
Mg matrix composites reinforced by natural bone constituent hydroxyapatite (HA) particles have shown promising in-vitro corrosion resistance but are inconsistent in both electrochemical and mechanical performances because of severe particle segregations. The present work was carried out to investigate the feasibility of a novel technology that combines high shear solidification and equal channel angular extrusion (ECAE) for fabricating Mg-HA nanocomposites. Experiments showed that the high shear solidification resulted in a fine and uniform grain structure with a globally uniform HA nanoparticles in fine clusters and the ECAE processing of the as-cast composites resulted in further grain refinement and more importantly the breakdown of nanoparticle aggregates, leading to the formation of a dispersion of true nanoparticles in the Mg alloy matrix with improved mechanical properties. This paper describes mainly the microstructural features and mechanical performance of Mg-3Zn-0.5Zr-xHA (x 1, 3, 5, 10) nanocomposites, in which the HA was in spherical shape with an average diameter of ∼20nm © Published under licence by IOP Publishing Ltd
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