Development of a sliding device for extended measurements in coastal waters

Extensive measurements of main sea water parameters (e.g. temperature, salinity, dissolved oxygen, nutrients, bacterial abundance...) are required to investigate marine environment, both to evaluate its state and to quickly detect possible perturbations (arrival of pollutants, anthropogenic contaminants...). Traditional observing methods cannot offer the flexibility and cost effectiveness needed for extensive monitoring and water quality assessment in coastal areas where important health and economic issues are involved (e.g. aquaculture, tourism). As a part of the MFSTEP program (EU FP5) a new device was designed and built for pelagic use, the SAVE (Sliding Advanced VEhicle), able to perform continuous profiles of physical and optical measurements on the upper 200 m of the water column. The original system consists mainly in a depressor, towed at a fixed depth, using a cable on which the main unit slides. Both the depressor and the sliding unit can be equipped with various kinds of sensors. The new goal was to obtain a coastal version, to be towed from small boats. A smaller prototype is now under development and test, able to be towed by a very small (8-10 m.) boat, like those commonly used in aquaculture plants, and also fitted with modular water samplers for bacterial or chemical determinations. The paper gives some first results of this development.L'articolo è disponibile sul sito dell'editore http://library.witpress.com

On total functional stability with two measures

A concept of total functional stability in terms of two different measuresis given. The theoretical results are obtained by mean of an extension of Liapunov'sdirect method

0-dimensional subschemes of curves lying on a smooth quadric surface

We characterize all the possible Hilbert functions for 0-dimensional subschemes of an irreducible curve C lying on a smooth quadric surface in the projective 3-space

On minimal Gorenstein Hilbert function

We conjecture that a class of Artinian Gorenstein Hilbert algebras called full Perazzo algebras always have minimal Hilbert function, fixing codimension and length. We prove the conjecture in length four and five, in low codimension. We also prove the conjecture for a particular subclass of algebras that occurs in every length and certain codimensions. As a consequence of our methods we give a new proof of part of a known result about the asymptotic behavior of the minimum entry of a Gorenstein Hilbert function.Comment: Accepted for publication in Revista de la Real Academia de Ciencias Exactas, F\'isicas y Naturales. Serie A. Matem\'atica

On stability for perturbed differential equations

This paper deals with a nonautonomous differential equation, precompact in the sense of G.R. Sell and Z. Artstein. We investigate the eventual asymptotic stability and total stability of this equation with infinitesimal perturbations using Liapunov function with semidefinite derivative

Partial Gorenstein in codimension 3

The goal of the paper is to build particular three codimensional arithmetically Cohen-Macaulay subschemes of P^r , partial Gorenstein schemes, whose graded Betti numbers can be easily computed in terms of their combinatorial support. This approach permits to realize many Betti sequences of schemes with the same Hilbert function