MOBILE ENVIRONMENTAL INFORMATION SYSTEMS

This paper presents the foundations for building mobile environmental information systems (MEISs) requiring an interdisciplinary approach. MEISs require expertise from the disciplines of environmental biology, geography, and mobile technology. MEISs show great promise for the acquisition of environmental information using different mobile devices. Automatic mobile acquisition enables the forwarding of the information to central databases for storage, further processing, and transmission to the mobile devices in a form that is useful to the users. Furthermore, these systems have the potential to be used both in the protection of nature, as well as in recreational use in a way that takes the constraints of nature into account. In this paper we describe the preliminary results of the MINNE project and the prototypes currently under research in the project.     

Effect of Adjusting the Water Activity to 0.95 with Different Solutes on the Kinetics of Thiamin Loss in a Model System

The kinetics of thiamin degradation in a model system of pH 6.0 and water activity (a_w) 0.95 controlled with NaCl, KC1, glycerol or Na₂SO₄, was studied. The type of solute used to adjust a_w, had a dramatic influence on the rate of degradation of thiamin. The loss of vitamin increased in the following order: NaCl > KCl > glycerol > Na₂SO₄. Activation energies, however, were independent of the type of solute and ranged between24–28 kcallmole.     

Review: Kinetic parameters for thiamine degradation in foods and model solutions of high water activity

Literature data for the rates of thiamine destruction in a wide variety of model systems, buffer solutions and foods have been used to determine the kinetics of thiamine destruction during processing. A range of conditions, including temperature, pH, oxygen and catalysts indicate that, in most cases, the destruction of thiamine follows first order reaction kinetics. When information is limited, these calculations may be used to extrapolate data and predict modifications of processing to minimize losses of thiamine.     

Identification of Gene encoding a Putative RNA-Helicase,Homologous to SKI2, in Chromosome VII of Saccharomyces cerevisiae

We have determined the nucleotide sequence of a segment of chromosome VII of the yeast Saccharomyces cerevisiae contained in the cosmid clone pEGH101 for a total of 7 kbp. This sequence contains a large open reading frame (ORF) called G9365, coding for a protein of 1967 amino acids that shows a significant homology with the product of the SKI2 gene of S. cerevisiae and contains domains characteristic of RNA-helicases. The ORF is transcribed in vegetative cells but it is not essential for viability as demonstrated by gene disruption. The sequence has been deposited in the GenBank data library under Accession Number U35242. © 1997 John Wiley & Sons, Ltd.     

COCHANNEL INTERFERENCE IN SATELLITE COMMUNICATION SYSTEMS DERIVED FROM RAIN ATTENUATION MEASUREMENTS AT 20 GHz

This paper reports experimental results on cochannel interference during rain, derived from measurements of simultaneous and copolar rain attenuations, in the 20 GHz band, in two convergent slant paths to fixed receivers at Spino d'Adda (Northern Italy), from the geostationary satellites Olympus (19°W) and Italsat (13°E). The results show that during rain the interference can be larger than that in clear sky, with probability 0.5 and that, in this case, the interfering level I = A_C − A_n (dB), i.e. the difference between the simultaneous rain attenuations (dB) in the interfered path, A_C (dB), and in the interfering path, A_n (dB), increases as the system power margin increases. For system design, the paper reports the cumulative distributions of I, conditioned to the maximum value of the attenuation not exceeded (i.e. system power margin) in the interfered link. It is shown how the results could be used in systems with regenerative or transparent transponders on board.     

TRANSIENT NATURAL DRYING-INDUCED BOUNDARY LAYERS

ABSTRACT

This work presents a methodology far obtaining heat and mass transfer coefficients for problems involving natural convection along a flat plate. In order to simulate drying conditions, a set of data has been obtained for the temperature range between 20 and 98° C and for various absolute humidities, both of the wall and ambient. It is shown that for drying at temperatures above 80° C, Nusselt and Sherwood numbers change very appreciably with respect to values obtained at smaller temperatures. The simulated results show that even for very low temperature differences, the transient period in natural convection along a flal vertical plate is smaller than 3s.     

ON THE PROPAGATOR OF THE STOKES EQUATION AND A DYNAMICAL DEFINITION OF VISCOSITY

The propagator of the unsteady Stokes equation is shown to be dominated by the solution of a purely diffusive equation, whose dispersion coefficient is the viscosity. Pressure plays an indirect role only, by creating instantaneously a steady velocity field which decays slowly in space. Viscosity appears to measure the temporal growth of the second moment of the unsteady Stokes propagator.