Aqueous alteration processes in Jezero crater, Mars—implications for organic geochemistry

The Perseverance rover landed in Jezero crater, Mars, in February 2021. We used the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument to perform deep-ultraviolet Raman and fluorescence spectroscopy of three rocks within the crater. We identify evidence for two distinct ancient aqueous environments at different times. Reactions with liquid water formed carbonates in an olivine-rich igneous rock. A sulfate-perchlorate mixture is present in the rocks, which probably formed by later modifications of the rocks by brine. Fluorescence signatures consistent with aromatic organic compounds occur throughout these rocks and are preserved in minerals related to both aqueous environments

Spatial Market Arbitrage and Threshold Cointegration

Goodwin and Piggott reported that corn and soybean prices in spatially separated markets in North Carolina exhibited threshold cointegration and that commodity prices in different markets may persistently diverge. Here, a multivariate approach is used to test for threshold cointegration and nonlinear cointegration. The results suggest that departures from the law of one price do not persist indefinitely. Copyright 2003, Oxford University Press.

Fractional integration in agricultural futures price volatilities revisited

Jin and Frechette (2004) examined the degree to which agricultural price volatilities exhibited evidence of fractional integration and concluded it was important to consider both long-run and short-run memory when modeling conditional variances. The purpose of this note is to revisit the issue using new methods and techniques which generally reaffirm the view that return volatilities are fractionally integrated and conditionally heteroskedastic, with many exhibiting significant leverage effects, a result not previously reported. Copyright (c) 2009 International Association of Agricultural Economists.

Modelling the Link between Commodity Prices and Exchange Rates: The Tale of Daily Data.

This paper examines daily data on exchange rates and the prices of three commodities traded on the Winnipeg Commodity Exchange. The temporal patterns of commodity prices and exchange rates are shown to be similar: daily data are significantly non-normal, with GARCH models capturing the processes generating the data. Commodity prices and exchange rates are examined for cointegration using recent tests proposed by Johansen and Juselius (1990). Currency depreciation is shown to Granger cause commodity price inflation. This information might be useful to central bankers concerned with reducing general price inflation through targeting commodity price inflation. It also suggests that macro events have important effects on commodity markets in Canada.