Nuestros investigadores

Sergio Ardanza-Trevijano Moras

Departamento
Física y Matemática Aplicada
Facultad de Ciencias. Universidad de Navarra
Líneas de investigación
Topology, Topological Data Analysis, Applied Algebraic Topology, Topological Groups
Índice H
6, (WoS, 30/08/2017)
7, (Scopus, 30/08/2017)

Publicaciones científicas más recientes (desde 2010)

Autores: Muhammad Aslam, Raheema; Ardanza-Trevijano Moras, Sergio; Poduska, K. M., ; et al.
Revista: PHYSICAL REVIEW E
ISSN 2470-0045  Vol. 95  Nº 3  2017  págs. 032607
Polycrystals of thin colloidal deposits, with thickness controlled by spin-coating speed, exhibit axial symmetry with local 4-fold and 6-fold symmetric structures, termed orientationally correlated polycrystals (OCPs). While spin-coating is a very facile technique for producing large-area colloidal deposits, the axial symmetry prevents us from achieving true long-range order. To obtain true long-range order, we break this axial symmetry by introducing a patterned surface topography and thus eliminate the OCP character. We then examine symmetryindependent methods to quantify order in these disordered colloidal deposits. We find that all the information in the bond-orientational order parameters is well captured by persistent homology analysis methods that only use the centers of the particles as input data. It is expected that these methods will prove useful in characterizing other disordered structures.
Autores: Ardanza-Trevijano Moras, Sergio; Zuriguel Ballaz, Iker; Arévalo, R., ; et al.
Revista: PHYSICAL REVIEW E
ISSN 1539-3755  Vol. 89  2014  págs. 052212
We use the first Betti number of a complex to analyze the morphological structure of granular samples in mechanical equilibrium. We investigate two-dimensional granular packings after a tapping process by means of both simulations and experiments. States with equal packing fraction obtained with different tapping intensities are distinguished after the introduction of a filtration parameter which determines the particles (nodes in the network) that are joined by an edge. This is accomplished by just using the position of the particles obtained experimentally and no other information about the possible contacts, or magnitude of forces.
Autores: Ardanza-Trevijano Moras, Sergio; Chasco Ugarte, María Jesús; Domínguez, X.; et al.
Revista: Forum Mathematicum
ISSN 0933-7741  Vol. 24  Nº 2  2012  págs. 289 - 302
Autores: Goñi Cortés, Joaquín; Arrondo Ostiz, Gonzalo; Sepulcre Bernad, Jorge; et al.
Revista: Cognitive Processing - Heidelberg
ISSN 1612-4782  Vol. 12  Nº 2  2011  págs. 183 - 186
Semantic memory is the subsystem of human memory that stores knowledge of concepts or meanings, as opposed to life-specific experiences. How humans organize semantic information remains poorly understood. In an effort to better understand this issue, we conducted a verbal fluency experiment on 200 participants with the aim of inferring and representing the conceptual storage structure of the natural category of animals as a network. This was done by formulating a statistical framework for co-occurring concepts that aims to infer significant concept-concept associations and represent them as a graph. The resulting network was analyzed and enriched by means of a missing links recovery criterion based on modularity. Both network models were compared to a thresholded co-occurrence approach. They were evaluated using a random subset of verbal fluency tests and comparing the network outcomes (linked pairs are clustering transitions and disconnected pairs are switching transitions) to the outcomes of two expert human raters. Results show that the network models proposed in this study overcome a thresholded co-occurrence approach, and their outcomes are in high agreement with human evaluations. Finally, the interplay between conceptual structure and retrieval mechanisms is discussed.
Autores: Goñi Cortés, Joaquín; Martincorena, I., ; Corominas-Murtra, B.; et al.
Revista: International Journal of Bifurcation and Chaos
ISSN 0218-1274  Vol. 20  Nº 3  2010  págs. 913 - 922
Semantic memory is the subsystem of human memory that stores knowledge of concepts or meanings, as opposed to life specific experiences. The organization of concepts within semantic memory can be understood as a semantic network, where the concepts (nodes) are associated (linked) to others depending on perceptions, similarities, etc. Lexical access is the complementary part of this system and allows the retrieval of such organized knowledge. While conceptual information is stored under certain underlying organization (and thus gives rise to a specific topology), it is crucial to have an accurate access to any of the information units, e. g. the concepts, for efficiently retrieving semantic information for real-time need. An example of an information retrieval process occurs in verbal fluency tasks, and it is known to involve two different mechanisms: "clustering", or generating words within a subcategory, and, when a subcategory is exhausted, "switching" to a new subcategory. We extended this approach to random-walking on a network (clustering) in combination to jumping (switching) to any node with certain probability and derived its analytical expression based on Markov chains. Results show that this dual mechanism contributes to optimize the exploration of different network models in terms of the mean first passage time. Additionally, this cognitive inspired dual mechanism opens a new framework to better understand and evaluate exploration, propagation and transport phenomena in other complex systems where switching-like phenomena are feasible.
Autores: Arévalo Turnes, Roberto; Zuriguel Ballaz, Iker; Ardanza-Trevijano Moras, Sergio; et al.
Revista: International Journal of Bifurcation and Chaos
ISSN 0218-1274  Vol. 20  Nº 3  2010  págs. 897 - 903
The existence of small order loops of contacts is presented as an intrinsic characteristic of force granular networks. Based on molecular dynamics simulations, it is proposed that the presence of these small order loops - and in particular third order loops of contacts - is important to understand the transition from fluid-like to solid-like behavior of granular packings. In addition, we show a close relationship between the development of third order loops and the small forces of the granular packing in the sense that almost all third order loops allocate a force component smaller than the average.