The Thesis: Commodity prices are significantly more volatile than prices of industrial products. Production as well as non speculative demand of raw materials are subject to stochastic - sometimes even systematic - fluctuations, which get translated into pronounced price fluctuations by low short run price elasticities of demand and supply. Unstable prices as such provide an incentive to speculate; and - so the Friedman thesis - profitable speculation in itself has a stabilizing effect, since "speculation can be destabilizing in general only if speculators on average sell when the currency is low in price and buy when it is high". Temporal independence between speculative and non speculative activities is the only necessary condition Friedman considers. The counter argument: As can be shown however, even under the assumption of temporal independence speculation can have a destabilizing effect despite being profitable, if the non speculative excess demand is nonlinear. Moreover its precisely because of temporal interdependence on commodity markets, that speculative profits can even be achieved by destabilizing (stable) prices. The extreme volatility of commodity prices therefore may be partly caused by (profitable) speculation as well. (author's abstract) / Series: Department of Economics Working Paper Series

Electrocatalysis plays a prominent role in renewable energy conversion and storage, enabling a number of sustainable processes for future technologies. There are generally three strategies to improve the efficiency (or activity) of the electrocatalysts: (i) increasing the intrinsic activity of the catalyst itself; (ii) improving the exposure of active sites; and (iii) acceleratingmass transfer during catalysis (both reactants and products). These strategies are not mutually exclusive and can ideally be addressed simultaneously, leading to the largest improvements in activity. Aerogels, as featured by large surface area, high porosity, and self-supportability provide a platform that matches all the aforementioned criteria for the design of efficient electrocatalysts. The field of aerogel synthesis has seen much progress in recent years, mainly thanks to the rapid development of nanotechnology. Employing precursors with different properties enables the resulting aerogel with targeted catalytic properties and improved performances. This report demonstrates the design strategies of aerogel catalysts and reviews their performances for several electrochemical reactions. The common principles that govern electrocatalysis are further discussed for each category of reactions, thus serving as a guide to the development of future aerogel electrocatalysts.