Now showing items 126-145 of 277

    • Generalization of Vélu’s formulae for isogenies between elliptic curves 

      Miret, Josep M. (Josep Maria); Moreno Chiral, Ramiro; Rio, Anna (Universitat Autònoma de Barcelona. Departament de Matemàtiques, 2007)
      Given an elliptic curve E and a finite subgroup G, V ́lu’s formulae concern to a separable isogeny IG : E → E ′ with kernel G. In particular, for a point P ∈ E these formulae express the first elementary symmetric polynomial ...
    • Geometric criterium in the center problem 

      Algaba, Antonio; García, Cristóbal; Giné, Jaume (Springer Basel, 2016-10)
      In this paper we use a geometric criterium based in the classical method of the construction of Lyapunov functions to determine if a differential system has a focus or a center at a singular point. This criterium is proved ...
    • Graphs, friends and acquaintances 

      Dalfó, Cristina; Fiol, Miguel Angel (Faculty of Mathematics and Natural SciencesInstitut Teknologi Bandung (ITB) IndonesiaIndonesian Combinatorial Society (InaCombS)GTA Research GroupGTA Research Group, 2018)
      A graph is a mathematical object modeling the existence of a certain relation between pairs of elements of a given set. Many of the first results concerning graphs made reference to relationships between groups of people. ...
    • Halving in some genus 2 curves over binary fields 

      Garra Oronich, Ricard; Miret, Josep M. (Josep Maria); Pujolàs Boix, Jordi (Institute of Electrical and Electronics Engineers (IEEE), 2016-06)
      We give a method to compute the halving of a divisor in the Jacobian variety of a genus 2 curve in characteristic 2. We present explicit halving formulae for each possible divisor class for some curves (those with h (x)= ...
    • Harvester ant nest distribution depends on soil disturbance regime 

      Baraibar Padró, Bàrbara; Torra Farré, Joel; Royo-Esnal, Aritz; Recasens i Guinjuan, Jordi; Comas Rodríguez, Carles (Elsevier, 2018-09-17)
      Nest densities of harvester ants (Messor barbarus) are high in rain-fed cereal fields in north-eastern Spain where the ants remove large quantities of seeds, contributing to reductions in weed populations. The distribution ...
    • Herramientas virtuales de simulación en la enseñanza de la astronomía diurna en futuros maestros de Primaria 

      Ibáñez, Manuel; Estrada Roca, M. Asunción; Barbero Sola, Iván (Edutec. Asociación para el Desarrollo de la Tecnología Educativa, 2017-03-01)
      Este trabajo presenta el impacto de la incorporación de herramientas virtuales de simulación de libre distribución combinadas con un modelo instruccional constructivista y dialógico en la docencia de la astronomía diurna ...
    • Higher Accuracy of Lung Ultrasound over Chest X-ray for Early Diagnosis of COVID-19 Pneumonia 

      Martínez Redondo, Javier; Comas Rodríguez, Carles; Pujol Salud, Jesús; Crespo Pons, Montserrat; García Serrano, Cristina; Ortega Bravo, Marta; Palacín Peruga, Jose María (MDPI, 2021)
      Background: The COVID-19 pandemic rapidly strained healthcare systems worldwide. The reference standard for diagnosis is a positive reverse transcription polymerase chain reaction (RTPCR) test, but results are not immediate ...
    • Highest weak focus order for trigonometric Liénard equations 

      Gasull, Armengol; Giné, Jaume; Valls, Claudia (Springer, 2020)
      Given a planar analytic differential equation with a critical point which is a weak focus of order k, it is well known that at most k limit cycles can bifurcate from it. Moreover, in case of analytic Liénard differential ...
    • Human-caused fire occurrence modelling in perspective: a review 

      Costafreda Aumedes, Sergi; Comas Rodríguez, Carles; Vega García, Cristina (CSIRO Publishing, 2017)
      The increasing global concern about wildfires, mostly caused by people, has triggered the development of human-caused fire occurrence models in many countries. The premise is that better knowledge of the underlying factors ...
    • Identifying codes in line digraphs 

      Balbuena Martínez, Camino; Dalfó, Cristina; Martínez Barona, Berenice (Elsevier, 2020-05-21)
      Given an integer ≥1, a (1, ≤ )-identifying code in a digraph is a dominating subset C of vertices such that all distinct subsets of vertices of cardinality at most have distinct closed in-neighborhoods within C . In ...
    • Idoneidad didáctica en educación infantil: matemáticas con robots Blue-Bot. 

      Ricart Aranda, María; Estrada Roca, M. Asunción; Margalef Martíl, María (Universidad de Córdoba, 2019)
      El objetivo de este trabajo es valorar la idoneidad didáctica de un proceso de enseñanza y aprendizaje de orientación espacial con el robot Blue-Bot. Primero, se contextualiza la experiencia innovadora implementada con ...
    • Importància didàctica de les actituds envers l'estadística en l'educació primària 

      Estrada Roca, M. Asunción (Associació de Mestres Rosa Sensat, 2013)
      L’estadística s’ha incorporat de manera generalitzada al currículum de l’Educació Primària, segons Estrada (2009), per raons fonamentalment socioculturals i educatives, i ha impulsat la investigació i el desenvolupament ...
    • Improving the peer-review process and editorial quality: key errors escaping the review and editorial process in top scientific journals 

      Margalida, Antoni; Colomer, M. Àngels (Maria Àngels) (PeerJ, 2016)
      We apply a novel mistake index to assess trends in the proportion of corrections published between 1993 and 2014 in Nature, Science and PNAS. The index revealed a progressive increase in the proportion of corrections ...
    • Inertial mass from Unruh temperatures 

      Giné, Jaume; McCulloch, M. E. (World Scientific Publishing, 2016)
      It has been proposed that inertia can be explained as follows: when objects accelerate in one direction a Rindler horizon forms in the other direction, suppressing Unruh radiation on that side, and producing a net Unruh ...
    • Inertial mass of an elementary particle from the holographic scenario 

      Giné, Jaume (World Scientific Publishing, 2017)
      Various attempts have been made to fully explain the mechanism by which a body has inertial mass. Recently it has been proposed that this mechanism is as follows: when an object accelerates in one direction a dynamical ...
    • Integrability conditions for complex kukles systems 

      Giné, Jaume; Valls, Claudia (Taylor & Francis, 2017)
      In this paper, we provide necessary and sufficient conditions for the existence of local analytic first integrals for a seventh-parameter family of complex cubic systems called the complex Kukles systems.
    • Integrability conditions for Lotka–Volterra planar complex quintic systems 

      Giné, Jaume; Romanovski, Valery G. (Elsevier, 2010)
      In this paper we obtain necessary and sufficient integrability conditions at the origin for the Lotka–Volterra complex quintic systems which are linear systems perturbed by fifth degree homogeneous polynomials, i.e., we ...
    • Integrability conditions of a resonant saddle in generalized Liénard-like complex polynomial differential systems 

      Giné, Jaume; Llibre, Jaume (Elsevier, 2017)
      We consider a complex differential system with a resonant saddle at the origin. We compute the resonant saddle quantities and using Gröbner bases we find the integrability conditions for such systems up to a certain degree. ...
    • Integrability conditions of a resonant saddle in Liénard-like complex systems 

      Giné, Jaume; Valls, Claudia (Elsevier, 2016)
      We consider a complex differential system with a resonant saddle that remind the classical Liénard systems in the real plane. For such systems we determine the conditions of analytic integrability of the resonant saddle.
    • Integrability conditions of a resonant saddle perturbed with homogeneous quintic nonlinearities 

      Giné, Jaume; Valls, Claudia (Springer, 2015)
      In this work we complete the integrability conditions (i.e. conditions for the existence of a local analytic first integral) for a family of a resonant saddle perturbed with homogeneous quintic nonlinearities studied in a ...