COMPLEX CDMA VERSUS FDMA/SCPC FOR LOW AND MEDIUM BIT RATE APPLICATIONS FOR FIXED SATELLITE SERVICES

In this paper, the performance of a DS-CDMA asynchronous satellite communication system, using four-phase sequences with near-optimum correlation properties, is analysed and compared with the result achievable by adopting the FDMA/SCPC approach. The comparison is carried out on the basis of the number of the simultaneous active channels in the network and of spectral efficiency. In addition, a similar CDMA system using four-phase sequences, constructed by means of binary Gold sequences having the same family size, has been analysed, and notable performance differences have been found. In particular, the use of four-phase near-optimal sequences provides an increase of about 50 per cent in the spectral efficiency. This result expands the convenience of using CDMA over a wider set of bit rate values, even for fixed satellite communications. Convolutional coding and Viterbi soft decoding are also included in the system. Simulation results are shown for some values of bit error probabilities of practical interest.     

State Ownership and the Evolution of Italian Corporate Governance

State ownership pyramidal groups, family trust and a minor rolefor banks and other financial institutions in the corporategovernance of both large and small enterprises are the structuralfeatures of Italian capitalism today. This paper offers a criticalanalysis of state ownership by analysing the evolution of Italiancorporate governance since the Second World War. It concludesthat full or majority state ownership of corporations can beeffective in separating ownership and control during stagesof powerfully accelerating growth and when shifts in the sectoralbalance are needed; that state-owned enterprises must not beburdened with ‘special social objectives’; and thatthe system is bound to degenerate without a functioning politicalmarket to guarantee democratic changes of parties and powerand if the ‘mission’ culture of public managersis eroded.     

Key Aspects of Catalyst Design for the Selective Oxidation of Paraffins

This review examines some aspects in the development of heterogenous catalysts for the oxyfunctionalization of light paraffins. Particular attention is devoted to the raction of paraffin oxydehydrogenation to olefins and of n-butane oxidation to maleic anhydride. Most catalyst compositions are based on vanadium oxide as the main component, and the peculiar properties of this element with respect to the catalytic performance are discussed. These properties are also examined in ligh of the stability of the product of partial oxidation towards consecutive unselective oxidation reactions, and with respect to the mechanism of paraffin activation.     

SURVIVAL OF LISTERIA INNOCUA IN APPLE JUICE AS AFFECTED BY VANILLIN OR POTASSIUM SORBATE

Survival of stationary phase Listeria innocua ( as surrogate microorganism for L. monocytogenes) inoculated in apple juice (pH 3.3 or 3.8) supplemented with vanillin (1,500 ppm or 3,000 ppm) or potassium sorbate (500 ppm or 1,000 ppm) and stored at room temperature was studied. L. innocua survived in apple juice without the preservatives at pH 3.3 or 3.8, with minimal population reductions. In the juices with the incorporation of potassium sorbate or vanillin , L. innocua behavior depended on the pH value, the type of antimicrobial and its concentration. At pH 3.3, the presence of vanillin (3,000 ppm) or potassium sorbate (1,000 ppm or 500 ppm) decreased L. innocua counts, with population reductions ranging from 4 to 5 log cycles after a 4 h – 8 h exposure at 30C. However, at pH 3.8 , L. innocua showed sensitivity only to 3,000 ppm vanillin. Survival curves were successfully fitted using a Weibull type distribution of resistances.
The results suggest that the use of potassium sorbate or vanillin could prevent the survival of L. innocua in contaminated unpasteurized and pasteurized apple juice. Vanillin, a natural antimicrobial, would be particularly suitable as an antilisterial additive for less acidic apple juice.     

Pilot Scale Dealcoholization of Wine by Extraction with Solid Carbon Dioxide

A pilot plant system for dealcoholizing wine using solid carbon dioxide snow was evaluated. Wines were stripped of alcohol content by spraying them over solid phase CO₂. Gas leaving the solid-liquid contact zone carried ethanol which was recovered by condensation. White wine lost alcohol easier than red wine and some higher alcohols were removed at levels which paralleled ethanol removal. Other solutes remained at about the same levels as in the untreated wine.