TILAPIA: BOTH FISH AND FOWL?

Tilapia aquaculture production is now around one million tonnes and is widely tipped to become an even bigger player in the international arena. This paper considers the case for such claims by reviewing the production environment, costs, the key characteristics of the product and its marketing with particular reference to the emergent EU markets and the increasingly established North American market. It is concluded that tilapia has quite distinct comparative advantages, not least being its diverse production scenarios, low cost, and product attributes which are commonly sought by consumers. Coupled with potentially green marketing attributes, it is concluded that this species is likely to appear in a broadening product range including more added value products.Resource /Energy Economics and Policy,

Odors: from chemical structures to gaseous plumes

We are immersed within an odorous sea of chemical currents that we parse into individual odors with complex structures. Odors have been posited as determined by the structural relation between the molecules that compose the chemical compounds and their interactions with the receptor site. But, naturally occurring smells are parsed from gaseous odor plumes. To give a comprehensive account of the nature of odors the chemosciences must account for these large distributed entities as well. We offer a focused review of what is known about the perception of odor plumes for olfactory navigation and tracking, which we then connect to what is known about the role odorants play as properties of the plume in determining odor identity with respect to odor quality. We end by motivating our central claim that more research needs to be conducted on the role that odorants play within the odor plume in determining odor identity

Kinosternon integrum

Number of Pages: 6Integrative BiologyGeological Science

Proportional-integral-plus (PIP) control of the ALSTOM gasifier problem

Although it is able to exploit the full power of optimal state variable feedback within a non-minimum state-space (NMSS) setting, the proportional-integral-plus (PIP) controller is simple to implement and provides a logical extension of conventional proportional-integral and proportional-integral-derivative (PI/PID) controllers, with additional dynamic feedback and input compensators introduced automatically by the NMSS formulation of the problem when the process is of greater than first order or has appreciable pure time delays. The present paper applies the PIP methodology to the ALSTOM benchmark challenge, which takes the form of a highly coupled multi-variable linear model, representing the gasifier system of an integrated gasification combined cycle (IGCC) power plant. In particular, a straightforwardly tuned discrete-time PIP control system based on a reduced-order backward-shift model of the gasifier is found to yield good control of the benchmark, meeting most of the specified performance requirements at three different operating points

Price Links between Auction and Direct Sales of Fresh and Frozen Fish in North Norway (1997–2003)

In North Norway the dominant method of exchange for fresh and frozen fish at the ex-vessel level is by direct (contract) sale, whereby price is negotiated between fish processors and the fishermen. More recently, an auction for frozen fish has been introduced. In this paper we investigate the relationship of prices between these methods of exchange and, in particular, whether the prices develop in a stable pattern between auction and direct sale by means of a cointegration analysis. Monthly prices of size-graded cod and haddock landed in the period 1997–2003 are analysed. For most months, frozen fish sold through auctions realised the highest price, followed by direct sales of fresh and frozen, respectively. Fish sold by auction exhibits a larger monthly variation in price than fish sold directly. Prices for cod were cointegrated to a larger degree than for haddock, and the cointegration was strongest for frozen cod. The analysis also demonstrates that the auction prices for frozen cod and haddock drive the direct sale prices of similar fish, both frozen and fresh, even though the quantity sold via direct sales is greater than that of auctions. Law of one price (LOP) and weak exogeneity were present for cod and haddock.Market linkages, cointegration, auction sale, direct sale, fresh fish, frozen fish, cod, haddock, North Norway, Resource /Energy Economics and Policy, Q22, C32, D44,