Anaí, una forma de publicación en la web

El presente artículo presenta la estrategia de creación de contenidos para la web desarrollada en la Universidad de Navarra. El objetivo de esta estrategia es lograr un sistema de creación de contenidos descentralizado, gracias al cual un profesor o una persona de administración o servicios, con conocimientos informáticos medios e incluso escasos pueda desarrollar contenidos de calidad

Correlation, Network and Multifractal Analysis of Global Financial Indices

We apply RMT, Network and MF-DFA methods to investigate correlation, network and multifractal properties of 20 global financial indices. We compare results before and during the financial crisis of 2008 respectively. We find that the network method gives more useful information about the formation of clusters as compared to results obtained from eigenvectors corresponding to second largest eigenvalue and these sectors are formed on the basis of geographical location of indices. At threshold 0.6, indices corresponding to Americas, Europe and Asia/Pacific disconnect and form different clusters before the crisis but during the crisis, indices corresponding to Americas and Europe are combined together to form a cluster while the Asia/Pacific indices forms another cluster. By further increasing the value of threshold to 0.9, European countries France, Germany and UK constitute the most tightly linked markets. We study multifractal properties of global financial indices and find that financial indices corresponding to Americas and Europe almost lie in the same range of degree of multifractality as compared to other indices. India, South Korea, Hong Kong are found to be near the degree of multifractality of indices corresponding to Americas and Europe. A large variation in the degree of multifractality in Egypt, Indonesia, Malaysia, Taiwan and Singapore may be a reason that when we increase the threshold in financial network these countries first start getting disconnected at low threshold from the correlation network of financial indices. We fit Binomial Multifractal Model (BMFM) to these financial markets.Comment: 32 pages, 25 figures, 1 tabl

Scalar--flat K\"ahler metrics with conformal Bianchi V symmetry

We provide an affirmative answer to a question posed by Tod \cite{Tod:1995b}, and construct all four-dimensional Kahler metrics with vanishing scalar curvature which are invariant under the conformal action of Bianchi V group. The construction is based on the combination of twistor theory and the isomonodromic problem with two double poles. The resulting metrics are non-diagonal in the left-invariant basis and are explicitly given in terms of Bessel functions and their integrals. We also make a connection with the LeBrun ansatz, and characterise the associated solutions of the SU(\infty) Toda equation by the existence a non-abelian two-dimensional group of point symmetries.Comment: Dedicated to Maciej Przanowski on the occasion of his 65th birthday. Minor corrections. To appear in CQ

Repensar la enseñanza universitaria desde las tecnologías de la información y la comunicación. Algunas experiencias de universidades de los Estados Unidos

Se ofrecen aquí algunas experiencias de Universidades de los Estados Unidos que puedan ayudar a repensar la enseñanza universitaria desde las tecnologías de la información y la comunicación

Promoción del uso del web docente en la Universidad de Navarra: estrategia seguida y evaluación

This paper presents the strategy adopted by the University of Navarre in school year 2001-2002 and 2002-2003 to promote the use of websites for academic purposes. Data on the outcome of the project implementation are also provided. The project implementation had several components. First, we developed an e-content creation tool called Anai that is user-friendly. This allows people with very few computer skills to develop high-quality websites that have versatile features like weblogs, assessment systems, discussion tools, etc. Second, we organized several training sessions on the use of these tools. Today, the number of professors using websites for academic purposes has increased significantly. At least 60% of the courses offered in the University of Navarre have a website. Nevertheless, among the professors, the level and extent of the use of the web vary considerably. 1) The content of most websites is limited to providing basic information about a course, such as course description, objectives, syllabus, criteria of evaluation, etc. 2) Some websites contain teaching notes, handouts and ideas to support students. The content is presented using a variety of formats such as Microsoft Word, Adobe PDF and Microsoft PowerPoint. 3) Very few courses use tools like forums, weblogs, assessment systems or digital video. The key elements to ensure the effective implementation of the project include the following: user-friendly tools, institutional support and sustained efforts to train the users

On the mass segregation of stars and brown dwarfs in Taurus

We use the new minimum spanning tree (MST) method to look for mass segregation in the Taurus association. The method computes the ratio of MST lengths of any chosen subset of objects, including the most massive stars and brown dwarfs, to the MST lengths of random sets of stars and brown dwarfs in the cluster. This mass segregation ratio (Lambda_MSR) enables a quantitative measure of the spatial distribution of high-mass and low-mass stars, and brown dwarfs to be made in Taurus. We find that the most massive stars in Taurus are inversely mass segregated, with Lambda_MSR = 0.70 +/- 0.10 (Lambda_MSR = 1 corresponds to no mass segregation), which differs from the strong mass segregation signatures found in more dense and massive clusters such as Orion. The brown dwarfs in Taurus are not mass segregated, although we find evidence that some low-mass stars are, with an Lambda_MSR = 1.25 +/- 0.15. Finally, we compare our results to previous measures of the spatial distribution of stars and brown dwarfs in Taurus, and briefly discuss their implications.Comment: 10 pages, 8 figures, accepted for publication in MNRA

Balancing Minimum Spanning and Shortest Path Trees

This paper give a simple linear-time algorithm that, given a weighted digraph, finds a spanning tree that simultaneously approximates a shortest-path tree and a minimum spanning tree. The algorithm provides a continuous trade-off: given the two trees and epsilon > 0, the algorithm returns a spanning tree in which the distance between any vertex and the root of the shortest-path tree is at most 1+epsilon times the shortest-path distance, and yet the total weight of the tree is at most 1+2/epsilon times the weight of a minimum spanning tree. This is the best tradeoff possible. The paper also describes a fast parallel implementation.Comment: conference version: ACM-SIAM Symposium on Discrete Algorithms (1993

On the formation of trapezium-like systems

We investigate the formation and evolution of high-order massive star multiples similar to the Trapezium in the Orion Nebula Cluster. We perform ensembles of N-body simulations of the evolution of N=1000 Orion-like clusters with initial conditions ranging from cool and clumpy to relatively smooth and relaxed. We find that trapezium-like systems are frequently formed in the first 2 Myr in initially cool and clumpy clusters and can survive for significant amounts of time in such clusters. We also find that these systems are highly dynamical entities, constantly interacting with the surrounding cluster, changing their appearance and membership regularly. The eventual decay of trapezium-like systems can even destroy the host cluster. We argue that the current state of any trapezium-like system is transient and care should be taken when analysing and drawing conclusions from a single snapshot in the life of a highly dynamic object.Comment: Accepted for publication in MNRAS. Supplementary material can be found at ftp://hydra.shef.ac.uk/pub/spg/TRAP_SUPLIMENTARY.pd