(Almost) efficient mechanisms for bilateral trading

This study evaluates the total length of tambaqui (Colossoma macropomum ) captured in the middle Solimões river and traded during seven years (1993, 1997 and 2000 to 2005) in the Tefé market, Amazon, Brazil. The Mamirauá Institute of Sustainable Development obtained measurements of the total lengths from 42207 individuals. The length average was 45.23 ± 6.29 cm (minim um of 13 cm and maximum of 105.5 cm ) and the mode was 45 cm . From the total tambaquis, 92.86% were smaller than 55 cm and 7.14% measured 58.24 ± 5.41 cm on average. Medium and standard deviation of the lengths recorded in all years showed sizes below the established by the environmental federal agency. The Kruskal Wallis test showed that there is no significant difference between the abundances and medium sizes of the captures during all months of the year. The historical data of the tambaqui fisheries for the middle Solimões region indicate that individuals of this species have been constantly captured at sizes below the minim um length of reproduction. Nine recommendations for tambaquis fisheries management in the region related to more efficient mechanisms of inspection, auto-ecology studies of the species, environmental protection, reduction of fishery pressure, diffusion and educational cam paigns that aim to correct exploitation of this resource are presented in this manuscript.

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Efficient Mechanisms for Public Goods with Use Exclusions

SSRN Electronic Journal ◽

10.2139/ssrn.249151 ◽

2000 ◽

Cited By ~ 4

Author(s):

Peter Norman

Keyword(s):

Public Goods ◽

Efficient Mechanisms

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Bearing Performance Limits With Grease Lubrication

World Tribology Congress III, Volume 2 ◽

10.1115/wtc2005-63205 ◽

2005 ◽

Cited By ~ 1

Author(s):

P. M. Cann ◽

A. A. Lubrecht

Keyword(s):

Surface Damage ◽

Design Parameters ◽

Performance Limits ◽

Grease Lubrication ◽

Lubricated Contacts ◽

System A ◽

Operating Limits ◽

Bearing Design ◽

Cage Effects ◽

Efficient Mechanisms

This paper has examined the influence of bearing design and operation in controlling lubricant supply to the contact zone. Grease lubricated contacts are liable to starvation and as a result the film thickness is reduced, this can result in surface damage or premature bearing failure. It is of obvious importance to know when starvation occurs and the effect of grease type, bearing design and operation on lubrication replenishment. The aim therefore is to develop a starvation parameter capable of predicting the operating limits for a particular bearing/grease system. A number of bearing design parameters are examined in the paper, these include cage design, ball spin and bearing size. Ball spin and cage effects can be efficient mechanisms for maintaining the lubricant supply to the track. Increased bearing size, line contact geometries and high load result in reduced lubricant replenishment of the contact. Using this analysis it will be possible to establish operating limits for families of bearings.

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