Out-of-equilibrium density dynamics of a spinful Luttinger liquid

Using a Luttinger liquid theory we investigate the time evolution of the particle density of a one-dimensional spinful fermionic system with open boundaries and subject to a finite-duration quench of the inter-particle interaction. Taking into account also the turning on of an umklapp perturbation to the system Hamiltonian as a result of the quench, we study the possible formation of a Wigner molecule inside the system, focusing in particular on the sudden and adiabatic regimes. We show that the creation of this correlated state is essentially due to the propagation of "light-cone" perturbations through system which arise after both switching on and switching off the quenching protocol and that its behavior strongly depends on the quench duration.Comment: 10 pages, 2 figures. Proceedings submitted to Nuovo Cimento C - Colloquia and Communications in Physic

Network recovery after massive failures

This paper addresses the problem of efficiently restoring sufficient resources in a communications network to support the demand of mission critical services after a large scale disruption. We give a formulation of the problem as an MILP and show that it is NP-hard. We propose a polynomial time heuristic, called Iterative Split and Prune (ISP) that decomposes the original problem recursively into smaller problems, until it determines the set of network components to be restored. We performed extensive simulations by varying the topologies, the demand intensity, the number of critical services, and the disruption model. Compared to several greedy approaches ISP performs better in terms of number of repaired components, and does not result in any demand loss. It performs very close to the optimal when the demand is low with respect to the supply network capacities, thanks to the ability of the algorithm to maximize sharing of repaired resources

On critical service recovery after massive network failures

This paper addresses the problem of efficiently restoring sufficient resources in a communications network to support the demand of mission critical services after a large-scale disruption. We give a formulation of the problem as a mixed integer linear programming and show that it is NP-hard. We propose a polynomial time heuristic, called iterative split and prune (ISP) that decomposes the original problem recursively into smaller problems, until it determines the set of network components to be restored. ISP's decisions are guided by the use of a new notion of demand-based centrality of nodes. We performed extensive simulations by varying the topologies, the demand intensity, the number of critical services, and the disruption model. Compared with several greedy approaches, ISP performs better in terms of total cost of repaired components, and does not result in any demand loss. It performs very close to the optimal when the demand is low with respect to the supply network capacities, thanks to the ability of the algorithm to maximize sharing of repaired resources

The forward kinematics of doubly-planar Gough-Stewart platforms and the position analysis of strips of tetrahedra

The final publication is available at link.springer.comA strip of tetrahedra is a tetrahedron-tetrahedron truss where any tetrahedron has two neighbors except those in the extremes which have only one. The problem of finding all the possible lengths for an edge in the strip compatible with a given distance imposed between the strip end-points has been revealed of relevance due to the large number of possible applications. In this paper, this is applied to solve the forward kinematics of 6-6 Gough-Stewart platforms with planar base and moving platform, a problem which is known to have up to 40 solutions (20 if we do not consider mirror configurations with respect to the base as different solutions).Peer ReviewedPostprint (author's final draft

Donafenib in Chinese patients with advanced hepatocellular carcinoma (HCC): Really a new standard of care, or should we change paradigm for drug development in HCC?

not availabl

Translation and the Internet : evaluating the Quality of Free Online Machine Translators

The late 1990s saw the advent of free online machine translators such as Babelfish, Google Translate and Transtext. Professional opinion regarding the quality of the translations provided by them, oscillates wildly from the «laughably bad» (Ali, 2007) to «a tremendous success» (Yang and Lange, 1998). While the literature on commercial machine translators is vast, there are only a handful of studies, mostly in blog format, that evaluate and rank free online machine translators. This paper offers a review of the most significant contributions in that field with an emphasis on two key issues: (i) the need for a ranking system; (ii) the results of a ranking system devised by the authors of this paper. Our small-scale evaluation of the performance of ten free machine translators (FMTs) in «league table» format shows what a user can expect from an individual FMT in terms of translation quality. Our rankings are a first tentative step towards allowing the user to make an informed choice as to the most appropriate FMT for his/her source text and thus produce higher FMT target text quality.Durant la darrera dècada del segle xx s'introdueixen els traductors online gratuïts (TOG), com poden ser Babelfish, Google Translate o Transtext. L'opinió per part de la crítica professional sobre aquestes traduccions es mou des d'una ingrata ridiculització (Ali, 2007) a l'acceptació més incondicional (Yang y Lange, 1998). Actualment, els estudis valoratius sobre els TOG són realment escassos, la majoria en format blog, mentre que la literatura sobre els traductors comercials és enorme. L'article que plantegem aporta una revisió de les principals contribucions i posa l'èmfasi bàsicament en dues qüestions: (i) necessitat d'un sistema de classificació (un rànquing) i (ii) descripció dels resultats obtinguts pel sistema de classificació ideat pels autors d'aquest article. L'avaluació que realitzem a petita escala es basa en l'anàlisi de l'actuació de deu TOG en un rànquing que posa de manifest les expectatives que en termes de qualitat de traducció pot esperar l'usuari. El resultat del rànquing ofereix a l'usuari els criteris que millor s'ajusten a cada cas, per tal d'utilitzar un traductor o un altre en funció del text original, i obtenir com a resultat una traducció de qualitat considerable

Correlating densities of centrality and activities in cities : the cases of Bologna (IT) and Barcelona (ES)

This paper examines the relationship between street centrality and densities of commercial and service activities in cities. The aim is to verify whether a correlation exists and whether some 'secondary' activities, i.e. those scarcely specialized oriented to the general public and ordinary daily life, are more linked to street centrality than others. The metropolitan area of Barcelona (Spain) is investigated, and results are compared with those found in a previous work on the city of Bologna (Italy). Street centrality is calibrated in a multiple centrality assessment (MCA) model composed of multiple measures such as closeness, betweenness and straightness. Kernel density estimation (KDE) is used to transform data sets of centrality and activities to one scale unit for correlation analysis between them. Results indicate that retail and service activities in both Bologna and Barcelona tend to concentrate in areas with better centralities, and that secondary activities exhibit a higher correlation