5,255 research outputs found

    Some structural and emergent trends in Social Housing in Portugal. Rethinking housing policies in times of crisis

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    First of all, this article intends to analyse some structural trends in social housing in Portugal, while relating it with its welfare state regime nature, namely its incipient and tardy character, one that is predominantly oriented towards sectors other than housing. Having other European countries as reference, with different welfare state regimes, we will then point substantive differences in dimension, weight, access forms and target public in this housing sector. Consequently, our main argument revolves around the consequences of a fragile public investment in this domain, which is further channelled in a disparate and bipolar way between a small public promotion of social housing and the incentive to homeownership. We chiefly discuss, as a consequence of this model, the narrowing profile of social housing publics, in a spatially (and temporally) concentrated rationale, gathering individuals with common vulnerability features, lacking the ability to engage in positive residential and social mobility paths. Secondly, we discuss how the current economic and financial crisis, along with profound sociodemographic and labour market changes, determines academics and policy-makers to rethink housing policies and the very role of the state. on the one hand, we are faced with the drastic reduction of state resources and its investment capacity; on the other hand, there is the emergence of new housing needs, as a result of the crisis and also due to more structural economic and social transformations. This context, not only in Portugal but also in Europe, jeopardises policies and housing systems as we now them so far, reintroducing the argument over access (and affordability) to housing by more heterogeneous groups than the common profile of social housing beneficiaries at the moment. We therefore question the role of the state, the rationale and articulation possibilities with other actors and sectors, the financing model and de variety of audiences for whom the right to housing is not yet (or not anymore) guaranteed.FCTinfo:eu-repo/semantics/publishedVersio

    About the ergodic regime in the analogical Hopfield neural networks. Moments of the partition function

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    In this paper we introduce and exploit the real replica approach for a minimal generalization of the Hopfield model, by assuming the learned patterns to be distributed accordingly to a standard unit Gaussian. We consider the high storage case, when the number of patterns is linearly diverging with the number of neurons. We study the infinite volume behavior of the normalized momenta of the partition function. We find a region in the parameter space where the free energy density in the infinite volume limit is self-averaging around its annealed approximation, as well as the entropy and the internal energy density. Moreover, we evaluate the corrections to their extensive counterparts with respect to their annealed expressions. The fluctuations of properly introduced overlaps, which act as order parameters, are also discussed.Comment: 15 page

    Producing more rice with less water from irrigated systems

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    Irrigation management / Water use efficiency / Crop production / Water requirements / Water balance / Rice / Water distribution / Irrigated farming / Productivity / On-farm research / Irrigation scheduling / Groundwater / Conjunctive use / Rehabilitation / Modernization / Farmer participation / Farming systems / Irrigation systems / Crop-based irrigation / Asia / Philippines / Sri Lanka / Bangladesh / China / Malaysia / USA

    O regulamento de uso da denominação de origem Vale dos Vinhedos: vinhos finos tranquilos e espumantes.

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    O Regulamento de Uso da Denominação de Origem Vale dos Vinhedos: Vinhos Finos. Tranquilos e Espumantes. A Denominação de Origem Vale dos Vinhedos. O Regulamento de Uso da Denominação de Origem Vale dos Vinhedos. A Operacionalização do Regulamento de Uso da Denominação de Origem Vale dos Vinhedos.bitstream/item/94689/1/doc084.pd

    The Relativistic Hopfield network: rigorous results

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    The relativistic Hopfield model constitutes a generalization of the standard Hopfield model that is derived by the formal analogy between the statistical-mechanic framework embedding neural networks and the Lagrangian mechanics describing a fictitious single-particle motion in the space of the tuneable parameters of the network itself. In this analogy the cost-function of the Hopfield model plays as the standard kinetic-energy term and its related Mattis overlap (naturally bounded by one) plays as the velocity. The Hamiltonian of the relativisitc model, once Taylor-expanded, results in a P-spin series with alternate signs: the attractive contributions enhance the information-storage capabilities of the network, while the repulsive contributions allow for an easier unlearning of spurious states, conferring overall more robustness to the system as a whole. Here we do not deepen the information processing skills of this generalized Hopfield network, rather we focus on its statistical mechanical foundation. In particular, relying on Guerra's interpolation techniques, we prove the existence of the infinite volume limit for the model free-energy and we give its explicit expression in terms of the Mattis overlaps. By extremizing the free energy over the latter we get the generalized self-consistent equations for these overlaps, as well as a picture of criticality that is further corroborated by a fluctuation analysis. These findings are in full agreement with the available previous results.Comment: 11 pages, 1 figur

    Elementary plastic events in amorphous silica

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    Plastic instabilities in amorphous materials are often studied using idealized models of binary mixtures that do not capture accurately molecular interactions and bonding present in real glasses. Here we study atomic-scale plastic instabilities in a three-dimensional molecular dynamics model of silica glass under quasistatic shear. We identify two distinct types of elementary plastic events, one is a standard quasilocalized atomic rearrangement while the second is a bond-breaking event that is absent in simplified models of fragile glass formers. Our results show that both plastic events can be predicted by a drop of the lowest nonzero eigenvalue of the Hessian matrix that vanishes at a critical strain. Remarkably, we find very high correlation between the associated eigenvectors and the nonaffine displacement fields accompanying the bond-breaking event, predicting the locus of structural failure. Both eigenvectors and nonaffine displacement fields display an Eshelby-like quadrupolar structure for both failure modes, rearrangement, and bond breaking Our results thus clarify the nature of atomic-scale plastic instabilities in silica glasses, providing useful information for the development of mesoscale models of amorphous plasticity

    Treatment with zygomatic implants in patients with advanced atrophy of maxilla

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    Introducción. El objetivo del presente estudio era mostrar los resultados del tratamiento con implantes cigomáticos utilizados en pacientes con atrofia maxilar severa. Metodos. 18 pacientes fueron tratados con 36 implantes cigomáticos Galimplant ® sumergidos con conexión interna para su rehabilitación prostodóncica. Las técnicas quirúrgicas de inserción de cigomáticos fueron extrasinusal y la técnica de la ranura sinusal. Los implantes fueron cargados después de un periodo de cicatrización de 6 meses. Resultados. Los hallazgos clínicos indican una supervivencia de los implantes del 100%. 14 implantes (38,9%) se in- sertaron por via extrasinusal y 22 implantes (61,6%) por la técnica de la ranura sinusal. Un total de 18 prótesis híbridas atornilladas fueron realizadas. Complicaciones postoperatorias fueron observadas en 4 pacientes (22,2%). El periodo medio de seguimiento clínico ha sido de 12 meses. Conclusiones. Este estudio indica que los implantes cigomáticos pueden ser utilizados con éxito en el tratamiento de los pacientes con atrofia maxilar severaThe aim of this study was to report the outcome of treatment with zygomatic implants used in patients with severe atrophy of maxilla. Methods. 18 patients were treated with 36 Galimplant ® zygomatic implants with internal connection for prosthodontic rehabilitation. Zygomatic surgical techniques were two approach for insertion of implants, extrasinusal and sinus slot technique. Implants were loaded after a healing free-loading period of six months. Results. Clinical results indicate a survival rate of implants of 100%. Fourteen implants (38.9%) were inser- ted by extrasinusal approach while twenty two implants were inserted by sinus slot approach (61.1%). A total of 18 hybrid screw prostheses were realized. Postoperative complications were observed in four patients (22.2%). The mean follow-up period were 12 months. Conclusions. This study indicate that zygomatic implants can be used with success in treatment of patients with severe atrophic maxilla

    Analogue neural networks on correlated random graphs

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    We consider a generalization of the Hopfield model, where the entries of patterns are Gaussian and diluted. We focus on the high-storage regime and we investigate analytically the topological properties of the emergent network, as well as the thermodynamic properties of the model. We find that, by properly tuning the dilution in the pattern entries, the network can recover different topological regimes characterized by peculiar scalings of the average coordination number with respect to the system size. The structure is also shown to exhibit a large degree of cliquishness, even when very sparse. Moreover, we obtain explicitly the replica symmetric free energy and the self-consistency equations for the overlaps (order parameters of the theory), which turn out to be classical weighted sums of 'sub-overlaps' defined on all possible sub-graphs. Finally, a study of criticality is performed through a small-overlap expansion of the self-consistencies and through a whole fluctuation theory developed for their rescaled correlations: Both approaches show that the net effect of dilution in pattern entries is to rescale the critical noise level at which ergodicity breaks down.Comment: 34 pages, 3 figure

    When gold stops glittering: corrosion mechanisms of René Lalique's Art Nouveau jewellery

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    ABSTRACT: Art Nouveau jewellery created by René Lalique is presently corroded. To identify the corrosion processes, Au-Ag-Cu alloys with compositions comparable to those used in the René Lalique’s jewellery were fabricated to be exposed to sulphide-containing environments. Using SEM-EDS, XRD, UV-Vis spectroscopy and ellipsometry, it was for the first time demon-strated that at the surface of tarnished Au alloys forms a corrosion film with a layer-by-layer structure. Considering the complex refractive indices of bulk Cu and Ag oxides and sulphides, a two-step corrosion mechanism was proposed. The formation of Cu-based compounds during the early corrosion stages is followed by the formation of Ag-based compounds. The thinness of the formed film, shown for one of the gold alloys to be of 80 nm, is due to a corrosion kinetics controlled by the presence of Au and by the formation of an Au-S self-assembled monolayer. The corrosion mechanism of gold alloys raises a new conservation challenge concerning the removal of nanometric layers.info:eu-repo/semantics/publishedVersio
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