Exponential behavior of the interlayer exchange coupling across non-magnetic metallic superlattices

It is shown that the coupling between magnetic layers separated by non-magnetic metallic superlattices can decay exponentially as a function of the spacer thickness $N$, as opposed to the usual $N^{-2}$ decay. This effect is due to the lack of constructive contributions to the coupling from extended states across the spacer. The exponential behavior is obtained by properly choosing the distinct metals and the superlattice unit cell composition.Comment: To appear in Phys. Rev.

Qualitative analysis of a scalar-tensor theory with exponential potential

A qualitative analysis of a scalar-tensor cosmological model, with an exponential potential for the scalar field, is performed. The phase diagram for the flat case is constructed. It is shown that solutions with an initial and final inflationary behaviour appear. The conditions for which the scenario favored by supernova type Ia observations becomes an attractor in the space of the solutions are established.Comment: Latex file, 9 pages, 1 figur

The business model through an ecosystem perspective: An exploratory approach applied to a cultural card

This paper aims to explore the relationship between the concepts of business model and ecosystem, applied to the creation of cultural cards that generate symbolic, cultural, social and economic value. This is a hybrid study - conceptual and empirical - and exploratory, based on literature review and data analysis collected by 602 questionnaires and 27 interviews. Was conducted a mixed methodology, qualitative and quantitative, and an interpretivist paradigm of constructivist nature. Three main conclusions were drawn. The first suggests that a cultural card is only viable if designed and managed as a business model, with all blocks coherent and articulated with each other and executed in synchronization. The second configures a cultural card as a complex network of interdependent actors functioning in an ecosystem logic that enhances economic growth affirmed by creative competitiveness. The third points out a cultural card as a cultural agent, for the symbolic value it promotes dominated by the discourse of ‘now’ and ‘already’, inherent in the access-based economy This paper: (1) perspectives that cultural and creative development involves the creation of a valuable macro ecosystem and a robust national network articulated with local and specific micro ecosystems; (2) evidences the importance of creativity and innovation, inherent to the business model, for the production and diffusion of knowledge, fruition and democratization of culture in the face of the diversity of emerging market segments and (3) provides propositions applicable to the universe of cultural and creative industries that are carriers of new insights that can be explored and knowledge increased. The value of this paper lies in the exploration of a new look at the theme of cultural cards embodied in a logic of an ecosystemic business model.info:eu-repo/semantics/publishedVersio

Two-component mixture of charged particles confined in a channel: melting

The melting of a binary system of charged particles confined in a {\it quasi}-one-dimensional parabolic channel is studied through Monte Carlo simulations. At zero temperature the particles are ordered in parallel chains. The melting is anisotropic and different melting temperatures are obtained according to the spatial direction, and the different types of particles present in the system. Melting is very different for the single-, two- and four-chain configurations. A temperature induced structural phase transition is found between two different four chain ordered states which is absent in the mono-disperse system. In the mixed regime, where the two types of particles are only slightly different, melting is almost isotropic and a thermally induced homogeneous distribution of the distinct types of charges is observed.Comment: To appear in Journal of Physics: condensed matter ; (13 pages, 12 figures