New method for rapid and sensitive quantification of sulphide-producing bacteria in fish from arctic and temperate waters

The offensive, fishy, rotten H2S-off-odours in spoiled, aerobically and cold stored fish from arctic and temperate waters are generally caused by sulphide-producing bacteria (SPB), mainly Shewanella putrefaciens. In the present work, a new, rapid, simple and accurate method for estimation of the SPB content in fish from these areas is described. The quantification is based on the formation rate of iron sulphide during growth of SPBs incubated at 30 degrees C in a liquid growth medium containing cysteine, sodium thiosulphate and iron(III)citrate as specific substrates for iron sulphide formation. The iron sulphide turns the medium grey and masks the background fluorescence in the medium when the SPB content in the assay is approximately 10(9) cfu/ml. The fluorescence change could be detected instrumentally and the colour change visually. The method was developed and evaluated in tests with S. putrefaciens CCUG 13452 DT as well as naturally occurring SPBs in cod, salmon, wolf fish and coal fish. A linear correlation between the SPB count and detection time was obtained over the entire range from 1 to 10(9) cfu SPB/g, corresponding to detection times 17 and 1 h, respectively. The correlation is described by the equation: log cfu/g fish= -0.59(+/- 0.17) x DT+ 9.65(+/- 0.09), where DT is the detection time in hours. The model was valid for all the tested fish species and all tested naturally occurring SPBs in these species. The regression coefficients (R2) for cod, coal fish, wolf fish and salmon were 0.99, 0.92, 0.97 and 0.97, respectively. The detection level of the method is 1 SPB per sample tube, corresponding to 16 cfu/g fish. The method could be used to predict the remaining shelf life of the fish for different markets, even when the time-temperature history during storage of the fish is unknown.     

Structure and elastic properties of hardened α+β titanium alloys

Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 35–38, January, 1990.     

Designing an electricity tax system in presence of international regulations and multiple public goals: An empirical assessment

The European competition rules restrict governments’ opportunity to differentiate terms of energy accessibility among firms and industries. This easily runs counter with regional and industrial goals of national energy policies. Norway levies a tax on use of electricity, but exempts main industrial usages. This analysis assesses alternative, internationally legal, designs of the system in terms of their effects on efficiency and distribution, including industrial objectives. Among the reforms we explore, removing the exemptions would be the most effective way of raising revenue, but it would be politically costly by deteriorating the competitiveness of today's favoured industries. An entire abolishment of the electricity tax, and replacing revenue by increased VAT, would generate a more equal distribution of standard of living and, at the same time, avoid the trade-off between efficiency and competitiveness.     

Can a carbon permit system reduce Spanish unemployment?

This paper analyses the impact of carbon policy on unemployment in Spain and whether recycling the public revenues earned from permit auctions can alleviate this problem. While Spain's deviation from the European Union's intermediate emission goals is more serious than most other member countries' unemployment in Spain is also well above average for the European Union. We use a computable general equilibrium model that includes unemployment in the markets for unskilled and skilled labour. We find that introducing carbon permits does not aggravate Spanish unemployment. In fact, if supplied with revenue recycling schemes, unemployment rates may actually fall. Contrary to other European studies, we find that the best option is to reduce payroll taxes on relatively skilled types of labour. This reform is successful in both increasing labour demand and dampening the supply response to rising wages. However, while all of the recycling schemes generate dividends in terms of aggregate welfare, none entirely offsets the abatement costs.     

Boolean Models of Reflexive Choice Control

The design of reflexive behavior models for situation specific choice is investigated under the assumption that the model is based on multi-valued Boolean scales. Conditions for a realistic choice under which an agent can realize his desires are formulated. Reflexive control and programming in which choice is subject to outer pressure are studied.     

Comparative study of active site structure in bovine and Pacific salmon trypsins

The kinetic investigation was carried out on the inhibition of hydrolysis of N, alpha-benzoyl-D, L-arginine-p-nitroanilide (BApNA) for bovine and salmon trypsin by phenylmethanesulphonyl fluoride (PMSF), N, alpha-tosyl-L-lysine chloromethyl ketone (N-TLCK), N, alpha-tosyl-L-phenylalanine chloromethyl ketone (N-TPCK). Kinetic parameters of inhibition (Ki, k2) by PMSF for salmon and bovine trypsin differ insignificantly. The k2/Ki value of N-TPCK for salmon trypsin is 10 times more than of bovine trypsin. Kinetic parameters of inhibition by N-TLCK had the less difference. The Ki value of this inhibitor for salmon trypsin is 5 times less than that of bovine trypsin and k2 value is 1.7 times less.