Two sided markets, competitive bottlenecks and exclusive contracts

We provide a framework for analyzing two-sided markets that allows for different degrees of product differentiation on each side of the market. When platforms are viewed as homogenous by sellers but heterogeneous by buyers, we show that “competitive bottlenecks” arise endogenously. In equilibrium, platforms do not compete directly for sellers, instead choosing to compete indirectly by subsidizing buyers to join. Sellers are left with none of the gains from trade. Despite this, it is sellers who choose to purchase from multiple platforms (multihome). Finally, the role of exclusive contracts to prevent multihoming is explored

Prominence and consumer search

This paper examines the implications of “prominence” in search markets. We model prominence by supposing that the prominent firm will be sampled first by all consumers. If there are no systematic quality differences among firms, we find that the prominent firm will charge a lower price than its non-prominent rivals. The impact of making a firm prominent is that it will typically lead to higher industry profit but lower consumer surplus and welfare. The model is extended by introducing heterogeneous product qualities, in which case the firm with the highest-quality product has the greatest incentive to become prominent, and making it prominent will boost industry profit, consumer surplus and welfare

A black shale protolith for gold-tellurium mineralisation in the Dalradian Supergroup (Neoproterozoic) of Britain and Ireland

The Dalradian Supergroup of Britain and Ireland is mineralised by gold-tellurium vein deposits. The host succession includes carbonaceous, pyritic shales (pelites) which were a source of trace elements, including gold and tellurium. LA-ICP-MS mapping of pyrite crystals shows that late stages are enriched in gold, tellurium and lead, representing concentration of these elements during metamorphism and related hydrothermal activity. The sulphur isotope composition of the pyrite varies with stratigraphic position, reflecting an origin for the pyrite in the depositional environment through microbial sulphate reduction. Where pyrite was converted to pyrrhotite, trace element contents are much lower, indicating element liberation during metamorphism. These observations are consistent with a model of black shale protoliths for orogenic gold deposits

Robust model-based controller synthesis for the SCOLE configuration

The design of a robust compensator is considered for the SCOLE configuration using a frequency-response shaping technique based on the LQG/LTR algorithm. Results indicate that a tenth-order compensator can be used to meet stability-performance-robustness conditions for a 26th-order SCOLE model without destabilizing spillover effects. Since the SCOLE configuration is representative of many proposed spaceflight experiments, the results and design techniques employed potentially should be applicable to a wide range of large space structure control problems

Coccidiosis in sheep

COCCIDIOSIS is an acute, contagious intestinal infection which may affect most species of animals and birds. The disease causes heavy losses in the poultry industry, and dogs, calves, sheep, goats and pigs are among other domesticated animals affected—but there is no cross-infection from one species of animal or bird to another. It is characterised by diarrhoea and severe loss of condition

Solar particle observations inside the magnetosphere during the 7 July 1966 event

Injun satellite observations of solar particles inside magnetospher