Modelling South African Currency Crises as Structural Changes in the Volatility of the Rand

This study tests the theory that currency crises are associated with sudden large changes in the structure of foreign exchange market volatility. Due to increases in market uncertainty, crisis periods exhibit abnormally high levels of volatility. By studying short-term changes in volatility dynamics, it is possible to identify the start- and end-dates of crisis periods with a high degree of precision. We use the iterative cumulative sum of squares algorithm to detect multiple shifts in the volatility of rand returns between January 1994 and March 2009. Dummy variables controlling for the detected shifts in variance are incorporated in a GARCH modelling framework. The analysis indicates that previously identified crisis periods in the rand coincide with significant structural changes in market volatility.Currency crisis, exchange rate, volatility, ICSS algorithm, GARCH

Lithium-ion battery thermal-electrochemical model-based state estimation using orthogonal collocation and a modified extended Kalman filter

This paper investigates the state estimation of a high-fidelity spatially resolved thermal- electrochemical lithium-ion battery model commonly referred to as the pseudo two-dimensional model. The partial-differential algebraic equations (PDAEs) constituting the model are spatially discretised using Chebyshev orthogonal collocation enabling fast and accurate simulations up to high C-rates. This implementation of the pseudo-2D model is then used in combination with an extended Kalman filter algorithm for differential-algebraic equations to estimate the states of the model. The state estimation algorithm is able to rapidly recover the model states from current, voltage and temperature measurements. Results show that the error on the state estimate falls below 1 % in less than 200 s despite a 30 % error on battery initial state-of-charge and additive measurement noise with 10 mV and 0.5 K standard deviations.Comment: Submitted to the Journal of Power Source

On the reliability of mean-field methods in polymer statistical mechanics

The reliability of the mean-field approach to polymer statistical mechanics is investigated by comparing results from a recently developed lattice mean-field theory (LMFT) method to statistically exact results from two independent numerical Monte Carlo simulations for the problems of a polymer chain moving in a spherical cavity and a polymer chain partitioning between two confining spheres of different radii. It is shown that in some cases the agreement between the LMFT and the simulation results is excellent, while in others, such as the case of strongly fluctuating monomer repulsion fields, the LMFT results agree with the simulations only qualitatively. Various approximations of the LMFT method are systematically estimated, and the quantitative discrepancy between the two sets of results is explained with the diminished accuracy of the saddle-point approximation, implicit in the mean-field method, in the case of strongly fluctuating fields.Comment: 27 pages, 9 figure

Arcuate nucleus homeostatic systems reflect blood leptin concentration but not feeding behaviour during scheduled feeding on a high-fat diet in mice

Acknowledgements T.B. was funded by a CASE studentship from the BBSRC and AstraZeneca. J.B. was a summer student from Bordeaux Sciences Agro and funded by student laboratory experience grant from the British Society of Neuroendocrinology. The authors are also grateful for funding from the Scottish Government, and from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreements 266408 (Full4Health) and 245009 (NeuroFAST).Peer reviewedPublisher PD

Where is SGR1806-20?

We apply a statistical method to derive very precise locations for soft gamma repeaters using data from the interplanetary network. We demonstrate the validity of the method by deriving a 600 arcsec^2 error ellipse for SGR1900+14 whose center agrees well with the VLA source position. We then apply it to SGR1806-20, for which we obtain a 230 arcsec^2 error ellipse, the smallest burst error box to date. We find that the most likely position of the source has a small but significant displacement from that of the non-thermal core of the radio supernova remnant G10.0-0.3, which was previously thought to be the position of the repeater. We propose a different model to explain the changing supernova remnant morphology and the positions of the luminous blue variable and the bursting source.Comment: 12 pages and 2 color figures, accepted for publication in Astrophysical Journal Letter

Deconstructing Voice-over-IP

Unified distributed configurations have led to many technical advances, including robots and flip-flop gates. In this work, authors show the synthesis of consistent hashing. We present new “fuzzy” archetypes, which we call ARGAS