Delay Line as a Chemical Reaction Network

Chemistry as an unconventional computing medium presently lacks a systematic approach to gather, store, and sort data over time. To build more complicated systems in chemistries, the ability to look at data in the past would be a valuable tool to perform complex calculations. In this paper we present the first implementation of a chemical delay line providing information storage in a chemistry that can reliably capture information over an extended period of time. The delay line is capable of parallel operations in a single instruction, multiple data (SIMD) fashion. Using Michaelis-Menten kinetics, we describe the chemical delay line implementation featuring an enzyme acting as a means to reduce copy errors. We also discuss how information is randomly accessible from any element on the delay line. Our work shows how the chemical delay line retains and provides a value from a previous cycle. The system's modularity allows for integration with existing chemical systems. We exemplify the delay line capabilities by integration with a threshold asymmetric signal perceptron to demonstrate how it learns all 14 linearly separable binary functions over a size two sliding window. The delay line has applications in biomedical diagnosis and treatment, such as smart drug delivery.Comment: 9 pages, 11 figures, 6 table

The Nature and Determinants of the Economic Currency Exposure of Non-Financial UK Firms

This study examines the sensitivity of sales, profit margins and input costs to exchange rate movements for non-financial, UK firms. The sample is a representative cross-section of larger, publicly-listed firms and is not limited to those directly involved in international trade. Surveyed firms provided data on both the direct and indirect components of economic exposure. As with other studies, we find a statistically significant relationship between a firm's exchange rate sensitivity and the degree to which it sells, sources, or funds itself internationally. Contrary to the theory on economic exposure, only one indirect detreminant, that for foreign-based competition, is unambiguously significant. The other indirect effects, the degree of production differentiation, the demand elasticity for a firm's output and common input currencies for competitors, are not significant in our models. Our examination of the interactive effects suggested by the theory of economic exposure shows no statistical relationship to firm's exchange rate sensitivity. We attribute the weak evidence for competitive effects to the complexities of the indirect determinants of economic exposure at the form-specific level

Company Value and Economic Currency Risk: an empirical study of UK-listed importers and exporters

This study examines the impact of economic currency exposure on UK share prices using both daily and monthly data. It makes use of survey information to identify two types of firm on the basis of exchange rate sensitivity of their sales volume and input prices, as being either exporters and importers. We then examine the relationship between the exchange rate and the share price of individual firms in our sample of importer and exporter firms. This is done for the period 1990 to June 1997 and the sub-periods October 1990 to August 1992, when the UK participated in the exchange rate mechanism, and August 1995 to June 1997, a period of sterling appreciation. The results showed a stronger currency effect on firm value during the ERM period than when sterling free-floated. The analysis is then extended to examining the effects of a range of individual currencies and indicate that individual firms have very different exposures to particular currencies. Overall our results indicate a weak relationship between our sample firms' share price and changes in the exchange rate. Key Words: economic exposure, foreign exchange, currency risk, firm value

The Impact of Tax Shocks and Oil Price Volatility on Risk - A Study of North Sea Oilfield Projects

We examine the impact of market volatility and increased fiscal take on risk in strategic natural resource projects. An increase in 2006 UK oilfield taxation is used as a natural experiment for assessing the impact of a fiscal increase on oilfield projects comprising 73% of UK reserves. Stochastic cash flow at risk models combine market volatility and tax-take at the oilfield level to extend earlier North Sea studies. We demonstrate that a 10% Secondary tax increase in a composite UKCS fiscal system with a-priori nonlinearity directly increases overall cost structures, resulting in a 14% decrease in project values, and significantly, a 67% risk increase for UK Oilfields. Risk effects are asymmetrical across the size varying sample, marginal prospects are most affected. Journal Classification: G12, G31, G32, H2