72 research outputs found

    Warm Little Inflaton becomes Dark Energy

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    We present a model where the inflaton field behaves like quintessence at late times, generating the present phase of accelerated expansion. This is achieved within the framework of warm inflation, in particular the Warm Little Inflaton scenario, where the underlying symmetries guarantee a successful inflationary period in a warm regime sustained by dissipative effects without significant backreaction on the scalar potential. This yields a smooth transition into a radiation-dominated epoch, at which point dissipative effects naturally shut down as the temperature drops below the mass of the fermions directly coupled to the inflaton. The post-inflationary dynamics is then analogous to a thawing quintessence scenario, with no kination phase at the end of inflation. Observational signatures of this scenario include the modified consistency relation between the tensor-to-scalar ratio and tensor spectral index typical of warm inflation models, the variation of the dark energy equation of state at low redshifts characteristic of thawing quintessence scenarios, and correlated dark energy isocurvature perturbations.publishe

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    The Railway Station as Urban Intermodal Center: A contribution to improve its facilities

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    The present and forthcoming living conditions show a type of European city which will not be able to further expand itself. The situation which awaits us is one of stability, and we will pay greater attention to the already existing city. Not only to the buildings of prestige but also to the big heritage of the industrialization of the last century. We refer to the buildings connected to production processes, now misused or in not in use, but who are strategically placed if we want to change a city's form and make it better. Amongst them, railways areas are of a special interest. If we consider the railway buildings, they are particularly wanted, because they are mostly located in central areas and display an architectural value, which made them over the decades urban landmarks. And they offer many chances of reconversion. Our research analyzes many examples from all over the world, which can be divided into two groups. On the one hand, there are railway buildings which undergo a refurbishing process, but keep their traditional function. On the other hand, we have railway buildings which change of use. In the former case the railway building often changes radically shape, to adapt to new volumes of passenger traffic, but it keeps its use, although it may also host new activities. But our research focuses on the latter, i.e. railway buildings which change radically their function, to meet new needs of the city. In this way we do not only reuse a building of great importance because of its urban context, but we stimulate a revamping process of the surrounding areas. At the same time we transform the building and we keep it operational. On the basis of the examples we studied, we are able to state that railway buildings, when they undergo a reconversion, become most frequently museums or shopping malls. The success of such a reconversion depends on the way we harmonize the architectural structure of the building, the transformation we plan and the new uses we want it to supply, i.e. on the compatibility between what the building may provide and what the citizens require. A railway building tends to be perceived as a void box because of its great empty spaces (the halls, the platforms, etc.). But that does not mean that it is open to any use. There are methods of analysis which help us understand the flexibility a given building has, i.e. the capability it has to accept new and different uses. The flexibility of a building depends on a series of features, which it has or has not. As a consequence, each building offers us information, which may vary by the years, that guide us when we reconvert it. In fact each building is more or less open to transformations and has an inner own logic, i.e. "a system of features and relations which make it be what it is". In the case of a building with strong physical and psychological features, if we change the position of its elements and/or change them, we obtain a new structure, but its meaning will still be similar to the original one. That reduces the spectrum of possible new uses

    Safety and immunogenicity of hepatitis A vaccine in infants: a candidate for inclusion in the childwood vaccination programme

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