Measurements of absolute, single charge-exchange cross sections of H+, He+ and He2+ with H2O and CO2

Absolute measurements have been made of single-electron charge-exchange cross sections of H+, He+, and He2+ in H2O and CO2 in the energy range 0.3-7.5 keV amu(-1). Collisions of this type occur in the interaction of solar wind ions with cometary gases and have been observed by the Giotto spacecraft using the Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) during a close encounter with comet Halley in 1986. Increases in the He+ ion density, and in the He2+ to H+ density ratio were reported by Shelley et al, and Fuselier et al. and were explained by charge exchange. However, the lack of reliable cross sections for this process made interpretation of the data difficult. New cross sections are presented and discussed in relation to the Giotto observations.

International order flows: Explaining equity and exchange rate returns

Macroeconomic models of equity and exchange rate returns perform poorly at high frequencies. The proportion of daily returns that these models explain is essentially zero. Instead of relying on macroeconomic determinants, we model equity price and exchange rate behavior based on a concept from microstructure – order flow. The international order flows are derived from belief changes of different investor groups in a two-country setting. We obtain a structural relationship between equity returns, exchange rate returns and their relationship to home and foreign equity market order flow. To test the model we construct daily aggregate order flow data from 800 million equity trades in the U.S. and France from 1999 to 2003. Almost 60% of the daily returns in the S&P100 index are explained jointly by exchange rate returns and aggregate order flows in both markets. As predicted by the model, daily exchange rate returns and order flow into the French market have significant incremental explanatory power for the daily S&P returns. The model implications are also validated for intraday returns.

Volatile and persistent real exchange rates with or without sticky prices

The flexible-price two-country monetary model is extended to include a consumption externality with habit persistence. Two methodologies are employed to explore this model's ability to generate volatile and persistent exchange rates. In the first, actual data is used for the exogenous driving processes. In the second, the model is simulated using estimated forcing processes. The theory, in both cases, is capable of explaining the high volatility and persistence of real and nominal exchange rates as well as the high correlation between real and nominal rates. © 2007 Elsevier B.V. All rights reserved.

Silica grain labelling and EDX spectroscopy; evidence for inter-grain diffusion of Pt(NH3)(4)(2+) species during Pt/SiO2 catalyst preparation by ionic exchange

Labelling of silica grains and energy dispersive X-ray spectroscopy (EDX) in a TEM-FEG (field emission gun) were used to demonstrate the migration of Pt(NH3)(4)(2+) species from one grain to another during Pt/SiO2 catalyst preparation by the ion-exchange procedure.