33,723 research outputs found
A theory of hyperfinite sets
We develop an axiomatic set theory -- the Theory of Hyperfinite Sets THS,
which is based on the idea of existence of proper subclasses of big finite
sets. We demonstrate how theorems of classical continuous mathematics can be
transfered to THS, prove consistency of THS and present some applications.Comment: 28 page
Inhibitor specificity of amine oxidase
Although at the present time it appears clear that amine oxidase oxidation of adrenalin, or other o-diphenolic pressor amines such as were studied by Richter (6), does not play a significant physiological role, it is equally clear that the inactivation of aliphatic amines, phenethylamine and probably 4-hydroxyphenethylamine (tyramine), does predominantly take place by amine oxidase oxidation. In view of the evidence from the experiments of Ewins and Laidlaw (8) and a later study by Guggenheim and Löffler (9), such amine oxidations chiefly occur in the liver. In the present studies, an attempt was made to value quantitatively the inhibition of some of these particular type compounds by certain types of amines which are not themselves oxidized by the enzyme system (see Alles and Heegaard (10))
Substrate specificity of amine oxidase
The tyramine oxidase activity of liver extracts found by Hare (1), the aliphatic amine oxidase activity of brain, kidney, and liver extracts observed by Pugh and Quastel (2), and the adrenalin oxidase activity of similar extracts noted by Blaschko, Richter, and Schlossman (3) were brought under a common enzyme view-point by the latter authors. They were able to show (4) that extracts of brain, instestine, kindey, and liver from a number of mammals or representatives of the birds, reptiles, amphibians, and fishes all acted to absorb oxygen in the presence of several amine substrates. Hare (1) had shown that tyramine and phenethylamine form ammonia in the course of such oxidations, and Richter (5) showed that an ethylamino and a dimethylamino compound, as well as a number of methylamino and amino compounds, all yield the corresponding alkyl-amines or ammonia in the enzymic oxidation.
The conslusion that the demonstrated variey of such enzymic activity can be acribed to the presence of a single type pf amine oxidase was dependent in large part on observations that the relative activities of a preparation from one source on a series of substrates bear some relation to the relative activities exhibited by a preparation from another source. Further evidence depended on the action of certain amines as inihibitors and apparent competition between substrates when two oxidizable substrates are present in the system. The degree to which relative activities of different enzyme preparations were constant in a series of substrates was not good in the data reported, and the fact that Hare (1) had not been able to note activity of the liver preparations she used upon adrenalin as the substrate appeared to require special explanations
ON PRICES OF FRESH AND FROZEN COD FISH IN EUROPEAN AND U.S. MARKETS
The purpose of this paper is to test for price linkages among European (France, Germany, and U.K.) and U.S. prices of whole fresh cod and frozen cod fillets. In testing for a cointegrated system, we use both the two-stage Engle-Granger and Johansen procedures. Short-run price dynamics are measured using an error-correction model. Based on monthly import price observations from 1980 to 1992, the empirical results show no long-run price relationships for fresh cod between European and U.S. markets, but we do measure long-run price linkages for frozen cod fillets. Within Europe the markets for both fresh and frozen cod product are well integrated. The U.S. fresh cod market is distinct and separate from European markets, while the U.S. frozen cod market shows no short-run links to European markets. There is weak evidence for a long-run international market in frozen cod fillets.Resource /Energy Economics and Policy,
THE ECONOMIC STRUCTURE OF HARVESTING FOR THREE VESSEL TYPES IN THE NORWEGIAN SPRING-SPAWNING HERRING FISHERY
Norwegian spring-spawning herring (Clupea harengus) is the largest fish stock in the North Atlantic and is harvested by many nations. The introduction of new technology in the 1960s resulted in a substantial increase in the efficiency of the fishing fleet. As a consequence, the stock was fished almost to extinction by the end of the 1960s. In the 1990s, the stock showed healthy growth and Total Allowable Catch (TAC) quotas have increased. This paper adds to the understanding of the harvesting process by providing measurements of the economic structure of the harvesting technology. For this fishery, Norway receives the largest share of the internationally determined TAC quota, and thus, the focus will be to investigate the harvesting process for three vessel types in the Norwegian fishing fleet: purse seiners, trawlers, and coastal vessels. Vessel- level cost and revenue data are available annually for these vessel types for the three-year period 1994–96. Estimates of input elasticities, economies of scale, and cost elasticities for a two-output cost function are reported.Resource /Energy Economics and Policy,
Differential operators and Cherednik algebras
We establish a link between two geometric approaches to the representation
theory of rational Cherednik algebras of type A: one based on a noncommutative
Proj construction, used in [GS]; the other involving quantum hamiltonian
reduction of an algebra of differential operators, used in [GG].
In the present paper, we combine these two points of view by showing that the
process of hamiltonian reduction intertwines a naturally defined geometric
twist functor on D-modules with the shift functor for the Cherednik algebra.
That enables us to give a direct and relatively short proof of the key result,
[GS, Theorem 1.4] without recourse to Haiman's deep results on the n! theorem.
We also show that the characteristic cycles defined independently in these two
approaches are equal, thereby confirming a conjecture from [GG].Comment: 37 p
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