Current Oscillations, Interacting Hall Discs and Boundary CFTs

In this paper, we discuss the behavior of conformal field theories interacting at a single point. The edge states of the quantum Hall effect (QHE) system give rise to a particular representation of a chiral Kac-Moody current algebra. We show that in the case of QHE systems interacting at one point we obtain a ``twisted'' representation of the current algebra. The condition for stationarity of currents is the same as the classical Kirchoff's law applied to the currents at the interaction point. We find that in the case of two discs touching at one point, since the currents are chiral, they are not stationary and one obtains current oscillations between the two discs. We determine the frequency of these oscillations in terms of an effective parameter characterizing the interaction. The chiral conformal field theories can be represented in terms of bosonic Lagrangians with a boundary interaction. We discuss how these one point interactions can be represented as boundary conditions on fields, and how the requirement of chirality leads to restrictions on the interactions described by these Lagrangians. By gauging these models we find that the theory is naturally coupled to a Chern-Simons gauge theory in 2+1 dimensions, and this coupling is completely determined by the requirement of anomaly cancellation.Comment: 32 pages, LateX. Uses amstex, amssymb. Typos corrected. To appear in Int. J. Mod. Phys.

Current Algebra and Conformal Field Theory on a Figure Eight

We examine the dynamics of a free massless scalar field on a figure eight network. Upon requiring the scalar field to have a well defined value at the junction of the network, it is seen that the conserved currents of the theory satisfy Kirchhoff's law, that is that the current flowing into the junction equals the current flowing out. We obtain the corresponding current algebra and show that, unlike on a circle, the left- and right-moving currents on the figure eight do not in general commute in quantum theory. Since a free scalar field theory on a one dimensional spatial manifold exhibits conformal symmetry, it is natural to ask whether an analogous symmetry can be defined for the figure eight. We find that, unlike in the case of a manifold, the action plus boundary conditions for the network are not invariant under separate conformal transformations associated with left- and right-movers. Instead, the system is, at best, invariant under only a single set of transformations. Its conserved current is also found to satisfy Kirchhoff's law at the junction. We obtain the associated conserved charges, and show that they generate a Virasoro algebra. Its conformal anomaly (central charge) is computed for special values of the parameters characterizing the network.Comment: 39 pages; Latex with 1 figure included in encapsulated postscript format. psbox.tex require

The impact of oil prices on soybeans commodity prices: asymmetric cointegration evidence

The increases in soybean commodity prices are attributed to increase in oil prices which have affected the prices of agricultural grains commodity products such as soybean oil price. The study investigates asymmetric relationship between soybeans commodity price and crude oil price using most recent data. In order to account for possible asymmetric effect of oil price on soybeans commodity price, the paper uses momentum threshold autoregressive (MTAR) models, developed by Enders and Siklos (2001). Empirical results reveal that soybeans commodity prices and crude oil prices are cointegrated and the adjustment process is asymmetric in MTAR-consistent result. Our findings confirm that increase in crude oil prices affects the soybeans commodity prices in an asymmetric ways. Specifically, soybeans commodity prices rise faster when crude oil price increases but there is no immediate offsetting effect when the crude oil prices decrease. In other words, the asymmetric effect of oil price-shocks is greater when oil price increases than when oil price decreases. Policymakers may use these results to design appropriate policies to curb the inflationary consequences of oil prices

Enhanced polysulphide redox reaction using a RuO₂ nanoparticle-decorated mesoporous carbon as functional separator coating for advanced lithium–sulphur batteries

A multi-functional RuO₂ nanoparticle-embedded mesoporous carbon-coated separator is used as an electrocatalytic and adsorbing polysulphide-net to enhance the redox reaction of migrating polysulphides, to improve active material utilization and boost the electrochemical performance of lithium–sulphur batteries

RESEARCH MOTC WITH EXAMPLES: AN INTERACTIVE AID FOR MULTIDIMENSIONAL HYPOTHESIS GENERATION

This paper reports on conceptual development in the areas of database mining, and knowledge discovery in databases (KDD). Our efforts have also led to a prototype implementation, called MOTC, for exploring hypothesis space in large and complex data sets. Our KDD conceptual development rests on two main principles. First, we use the crosstab representation for working with qualitative data. This is by now standard practice in OLAP (on-line analytical processing) applications and we reaffirm it with additional reasons. Second, and innovatively, we use Prediction Analysis as a measure of goodness for hypotheses. Prediction Analysis is an established statistical technique for analysis of associations among qualitative variables. It generalizes and subsumes a large number of other such measures of association, depending upon specific assumptions the user is willing to make. As such, it provides a very useful framework for exploring hypothesis space in a KDD context. The paper illustrates these points with an extensive discussion of MOTC