We study here the behaviour of non-spacelike geodesics in dust collapse models in order to understand the casual structure of the spacetime. The geodesic families coming out, when the singularity is naked, corresponding to different initial data are worked out and analyzed. We also bring out the similarity of the limiting behaviour for different types of geodesics in the limit of approach to th...

We investigate the differential geometric ingredients for Whitney umbrella, which is known as the only stable singularity of surface to 3-dimensional Euclidean space. We obtain several criteria of the singularity types of fronts of Whitney umbrella in terms of differential geometric language we discuss.

Conditions under which gravity coupled to self interacting scalar field determines singularity formation are found and discussed. It is shown that, under a suitable matching with an external space, the boundary, if collapses completely, may give rise to a naked singularity. Issues related to the strength of the singularity are discussed.

First of all we discuss the different conceptual interpretations of sustainable development among the scientific community. Afterwards we use the epistemological concept of research traditions in order to explain this diversity of interpretations and its impacts on the prospects for technological development. As a third step we develop an approach to sustainable technology and show why such an ...

The aim of this article is to study the asymptotic behaviour of some low-cost control problems. These problems motivate the study of H-convergence with weakly converging data. An improved lower bound for the limit of energy functionals corresponding to weak data is established, in the periodic case. This fact is used to prove the Γconvergence of a low-cost problem with Dirichlet-type integral. ...

The European Citizens’ Initiative is designed to make European democracy more direct by allowing citizens to propose (including electronically) legal acts to the Commission. The present paper offers a conceptual model for the analysis of this eParticipation case, and other similar e-petitioning practices, which is not biased by political ambition or technological determinism. The operational fr...

This paper compares groups of firms with different technological capabilities in Bangkok (Thailand), Penang (Malaysia) and Singapore in respect to their innovation activity, cooperation behaviour and assessment of the business environment. While conspicuous differences between the regions are found, the comparison of the different technological capabilitygroups is less conclusive. However, some...

Let A be à transcendental entire function of order < 1. If w, and w2 are two linearly independent solutions of the differential equation y" + A y — 0, then at least one of wl, w2 has the property that the exponent of convergence of its zeros is > 1.