Four-dimensional gravity on supersymmetric dilatonic domain walls

We investigate the localization of four-dimensional metastable gravity in supersymmetric dilatonic domain walls through massive modes by considering several scenarios in the model. We compute corrections to the Newtonian potential for small and long distances compared with a crossover scale given in terms of the dilatonic coupling. 4D gravity behavior is developed on the brane for distance very much below the crossover scale, while for distance much larger, the 5D gravity is recovered. Whereas in the former regime gravity is always attractive, in the latter regime due to non-normalizable unstable massive graviton modes present on the spectrum, in some special cases, gravity appears to be repulsive and signalizes a gravitational confining phase which is able to produce an inflationary phase of the Universe.Comment: 11 pages, 4 figures, Latex. Version to appear in PL

Domain wall description of superconductivity

In the present work we shall address the issue of electrical conductivity in superconductors in the perspective of superconducting domain wall solutions in the realm of field theory. We take our set up made out of a dynamical complex scalar field coupled to gauge field to be responsible for superconductivity and an extra scalar real field that plays the role of superconducting domain walls. The temperature of the system is interpreted through the fact that the soliton following accelerating orbits is a Rindler observer experiencing a thermal bath.Comment: 9 pages, 5 figures, Latex. Version to appear in PL

Relaxing to a three dimensional brane junction

We suggest a mechanism which leads to 3+1 space-time dimensions. The Universe assumed to have nine spatial dimensions is regarded as a special nonlinear oscillatory system -- a kind of Einstein solid. There are p-brane solutions which manifest as phase oscillations separating different phase states. The presence of interactions allows for bifurcations of higher dimensional spaces to lower dimensional ones in the form of brane junctions. We argue this is a natural way to select lower dimensions.Comment: RevTex, 5 pages; version to appear in Europhys. Let

Environmental technology education in Portugal : analysis and perspectives

The scope of the present communication is the current status of environmental engineering in Portugal. The different approaches concerning the environmental engineering courses available at undergraduate levels as well as some post-graduation studies are described. Furthermore, an analysis based on strengths, weakness, opportunities and trend issues regarding the environmental engineering profession in Portugal is presented

Tratamento anaeróbio de efluentes líquidos industriais: alguns pontos focais

Esta comunicação aborda os fundamentos bioquímicos e microbiológicos que condicionam a concepção de reactores anaeróbios para tratamento de efluentes líquidos industriais e, complementarmente, apresenta vários aspectos referentes ao projecto de sistemas anaeróbios indicando alguns factores da opção aerobiose/anaerobiose, principais tipos de reactores e uma menção a aplicações industriais conhecidas

Mass transfer coefficients within anaerobic biofilms effects of external liquid velocity

This work concerns mass transport in anaerobic biofilms, formed under upflow liquid velocities similar to the prevailing conditions in anaerobic reactors used for wastewater treatment. During biofilm formation under liquid velocities of 1.5 and 13.2 m/h, internal mass transfer coefficients were routinely measured. Mass transfer coefficients attained pseudo steady-state values between 2-4 x 10ˉ³ m/h, no dependence being observed between bulk flow and internal mass transport rates. However, a transient variation in the liquid velocity from 1.5 up to 13.2 m/h, imposed after the biofilm had reached the steady-state, increased the internal mass transport by 20% on average. This result suggests that periodic changes in the bulk fluid velocity can be used as a tool to increase the transport of soluble substrates inside already formed biofilms, although the effect seems to be limited.Fundação para a Ciência e a Tecnologia (FCT) - PRAXIS XXI (2/2.1/BIO/37/94). European Commission

Moving to the cloud: Estimating the internet connection bandwidth

IT Infrastructures (ITIs) have long been understood in terms of people and resources such as servers, routers, firewalls and operating systems, among other components, running and providing services inside the organization. The need to reduce the cost of ITI ownership, by offloading its capacity to third parties, has motivated organizations to consider the Cloud Computing alternative. The main drawback they face when opting for the cloud is the dependency on and requirements of the internet connection, since it must be fast and reliable. This paper addresses this concern by providing guidelines for estimating internet connection bandwidth requirements for a prototypical cloud-based organization represented by means of an IT infrastructure pattern. ITI patterns are reusable and proven solutions to support the ITI design process and to facilitate the communication among stakeholders.info:eu-repo/semantics/acceptedVersio