The economics of debt clearing mechanisms

We examine the evolution of decentralized clearinghouse mechanisms from the 13th to the 18th century; in particular, we explore the clearing of non- or limitedtradable debts like bills of exchange. We construct a theoretical model of these clearinghouse mechanisms, similar to the models in the theoretical matching literature, and show that specific decentralized multilateral clearing algorithms known as rescontre, skontrieren or virement des parties used by merchants were efficient in specific historical contexts. We can explain both the evolutionary self-organizing emergence of late medieval and early modern fairs, and its robustness during the 17th and 18th century

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Das englische Geschwornengericht.

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Worksite tobacco prevention in the Canton of Zurich: stages of change, predictors, and outcomes

OBJECTIVES: This study provides information about the prevalence of tobacco prevention (TP) and the stages of change with respect to the introduction of TP among companies in the Canton of Zurich (n = 1,648). It explores the factors that predict restrictiveness of smoking policies, number of individual support measures, interest in services to promote TP, and the relationship between TP and health outcomes. METHODS: Data were gathered by means of a written questionnaire and analysed using ordinal regression models. RESULTS: Whereas many companies maintain smoke-free policies, only few provide cessation-courses. Health and welfare organisations have strictest, and building and hospitality companies have least strict policies. Company size predicts number of individual support measures but not policy restrictiveness. Both measures are predicted by personal concern of the representative. Interest in services is predicted by tobacco-related problems and medium stages of change. Finally, stricter policies are associated with lower proportion of smokers and less tobacco-related problems. CONCLUSIONS: Health professionals should support less advanced companies in their endeavour to implement TP. The findings provide a baseline to evaluate the implementation of the forthcoming smoke-free legislation