Functional adaptivity for digital library services in e-infrastructures: the gCube approach

We consider the problem of e-Infrastructures that wish to reconcile the generality of their services with the bespoke requirements of diverse user communities. We motivate the requirement of functional adaptivity in the context of gCube, a service-based system that integrates Grid and Digital Library technologies to deploy, operate, and monitor Virtual Research Environments defined over infrastructural resources. We argue that adaptivity requires mapping service interfaces onto multiple implementations, truly alternative interpretations of the same functionality. We then analyse two design solutions in which the alternative implementations are, respectively, full-fledged services and local components of a single service. We associate the latter with lower development costs and increased binding flexibility, and outline a strategy to deploy them dynamically as the payload of service plugins. The result is an infrastructure in which services exhibit multiple behaviours, know how to select the most appropriate behaviour, and can seamlessly learn new behaviours

Optical Properties of Graphene Nanoflakes: Shape Matters

In recent years there has been significant debate on whether the edge type of graphene nanoflakes (GNF) or graphene quantum dots (GQD) are relevant for their electronic structure, thermal stability and optical properties. Using computer simulations, we have proven that there is a fundamental difference in the calculated absorption spectra between samples of the same shape, similar size but different edge type, namely, armchair or zigzag edges. These can be explained by the presence of electronic structures near the Fermi level which are localized on the edges. These features are also evident from the dependence of band gap on the GNF size, which shows three very distinct trends for different shapes and edge geometries.Comment: 8 pages, 9 figures. Submitted to The Journal of Chemical Physic

Clashes and Compromises: Investment Policies in Tourism Destinations

The authors solve a linear problem where a potential conflict between two agents (Destination manager and Firm) arises in a tourism destination. The Destination manager has to choose how to allocate limited resources (capital and land) between either second homes or hotels. This conflict stems from the assumption of agents who have different linear preferences with respect to the allocation of limited resources. As a solution to this policy problem the authors consider three different policies: no intervention (laissez faire), taxation and temporary de-taxation policy. Comparing these different policies, they show that a compromise solution (internal solution), which results from the de-taxation policy, may be preferred by both agents over the clash of interests outcomes (corner solutions). Thus, the authors show that in a framework of \u201cconflict\u201d between agents a compromise solution may be preferable to both the absence of public intervention and the imposition of a tax by a public policy maker who has the discretionary \u201cpower to regulate\u201d conflicts

Systematic and biostratigraphic significance of a chinchillid rodent from the Pliocene of eastern Argentina

Two species of chinchillid rodents, Lagostomus (Lagostomopsis) incisus and “Lagostomus (Lagostomopsis) spicatus”, have been recorded from the Monte Hermoso Formation (Montehermosan–Lower Chapadmalalan, Early Pliocene) of southern Buenos Aires Province, eastern Argentina. L. (L.) incisus is based on skull remains,while “L. (L.) spicatus” is based on mandible remains and fragmentary skulls. Detailed study of specimens recovered from the upper section of the Monte Hermoso Formation, from the Irene “Formation”, and the Chapadmalal Formation (late Early–early Late Pliocene, Buenos Aires Province), some of them represented by associated skull and mandible remains, indicates that L. (L.) incisus and “L. (L.) spicatus” are synonymous, with the valid name being L. (L.) incisus. The differences between both nominal species are here attributed to different ontogenetic states and sexual dimorphism. The stratigraphic provenance of the fossil material of L. (L.) incisus indicates a temporal distribution of this species restricted to the Montehermosan?–Chapadmalalan (Early–early Late Pliocene), instead of the Montehermosan (Early Pliocene).Facultad de Ciencias Naturales y Muse

On General Plane Fronted Waves. Geodesics

A general class of Lorentzian metrics, $M_0 x R^2$, $ds^2 = + 2 du dv + H(x,u) du^2$, with $(M_0,$ any Riemannian manifold, is introduced in order to generalize classical exact plane fronted waves. Here, we start a systematic study of their main geodesic properties: geodesic completeness, geodesic connectedness and multiplicity, causal character of connecting geodesics. These results are independent of the possibility of a full integration of geodesic equations. Variational and geometrical techniques are applied systematically. In particular, we prove that the asymptotic behavior of $H(x,u)$ with $x$ at infinity determines many properties of geodesics. Essentially, a subquadratic growth of $H$ ensures geodesic completeness and connectedness, while the critical situation appears when $H(x,u)$ behaves in some direction as $|x|^2$, as in the classical model of exact gravitational wave

Probabilistic movement modeling for intention inference in human-robot interaction.

Intention inference can be an essential step toward efficient humanrobot interaction. For this purpose, we propose the Intention-Driven Dynamics Model (IDDM) to probabilistically model the generative process of movements that are directed by the intention. The IDDM allows to infer the intention from observed movements using Bayes ’ theorem. The IDDM simultaneously finds a latent state representation of noisy and highdimensional observations, and models the intention-driven dynamics in the latent states. As most robotics applications are subject to real-time constraints, we develop an efficient online algorithm that allows for real-time intention inference. Two human-robot interaction scenarios, i.e., target prediction for robot table tennis and action recognition for interactive humanoid robots, are used to evaluate the performance of our inference algorithm. In both intention inference tasks, the proposed algorithm achieves substantial improvements over support vector machines and Gaussian processes.

Interstitial gas and density-segregation in vertically-vibrated granular media

We report experimental studies of the effect of interstitial gas on mass-density-segregation in a vertically-vibrated mixture of equal-sized bronze and glass spheres. Sufficiently strong vibration in the presence of interstitial gas induces vertical segregation into sharply separated bronze and glass layers. We find that the segregated steady state (i.e., bronze or glass layer on top) is a sensitive function of gas pressure and viscosity, as well as vibration frequency and amplitude. In particular, we identify distinct regimes of behavior that characterize the change from bronze-on-top to glass-on-top steady-state.Comment: 4 pages, 5 figures, submitted to PRL; accepted in PRE as rapid communication, with revised text and reference