Abstract
It is shown that in using the Laplace transform one has to start with the condition that imposes f(0-) = 0 in order to avoid errors in the derivative and integral operations. In that case the matrix representation of the circuits using the Laplace transform becomes possible and the resolution of integral-differential equations is straightforward. Nevertheless, it is possible to use the Laplace transform with signals that have no null initial conditions, keeping the mathematical coherence, by choosing between two ways: (1) shifting the origin of time domains to the left to obtain the null initial conditions, and (2) using the superposition theorem to obtain one partial signal with null initial conditions.

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Abstract
This paper describes an architecture which can be used to access geographic information from mobile devices with limited display and processing characteristics, such as Personal Digital Assistants (PDA) or Mobile Phones. The information may come from different sources leading to an interoperable solution. M-GIS obtains geographic information from sources described using Geogxraphy Markup Language (GML) from one or more Web Feature Servers allowing an access independent from its format or physical location, as long as the information is according to the specification. Using XSLT, GML is transformed to a graphical format in Scalable Vector Graphics (SVG) which can then be manipulated in the mobile device. M-GIS follows a client/server architecture and the client application was developed using Java Mobile Information Device Profile technology. The results enable us to conclude that the mobile system, designed and developed with the use of open standards and representation formats to access geographic information, is a viable solution with some limitations. The main limitations of this approach have to do with the amount of information which the client can, at the moment, accommodate.

Abstract
Geographical information is of strategic importance, when comes to land use management decision-making and GIS are essential resources for the production of land use management instruments, commonly known as plans (e.g. master plans). To build them, local authorities require multi-disciplinary teams with different competences and responsibilities. Many of these teams are external to the municipality and in the position of sub-contractors. With so many actors involved, the result is often a complex mesh of incoherent spatial data. Overcoming this problem often leads to huge overheads for the public administration. This paper addresses a possible technical solution for this issue, based on international standards (e.g. OpenGIS) and profiting from the current state of technological development.

Abstract
This document describes how we are using mobile phones together with Google Earth to allow children to create multisensory geographic information in learning and participatory contexts.