Price indices for artists - A proposal

This paper proposes a price index for artists based on the ratio between the average market price and the average estimated price of the paintings sold by an artist each year, adjusted for market dynamics. We apply this methodology to a group of selected artists and schools drawing from a database including auction prices and estimated prices of paintings presented in auctions world wide between 1990 and 2001. A comparison with quality unadjusted and hedonic indices is also proposed

Optimal performance of endoreversible quantum refrigerators

The derivation of general performance benchmarks is important in the design of highly optimized heat engines and refrigerators. To obtain them, one may model phenomenologically the leading sources of irreversibility ending up with results that are model independent, but limited in scope. Alternatively, one can take a simple physical system realizing a thermodynamic cycle and assess its optimal operation from a complete microscopic description. We follow this approach in order to derive the coefficient of performance at maximum cooling rate for any endoreversible quantum refrigerator. At striking variance with the universality of the optimal efficiency of heat engines, we find that the cooling performance at maximum power is crucially determined by the details of the specific system-bath interaction mechanism. A closed analytical benchmark is found for endoreversible refrigerators weakly coupled to unstructured bosonic heat baths: an ubiquitous case study in quantum thermodynamics