491 research outputs found

    Integration of differential equations by C\mathcal{C}^{\infty}-structures

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    Several integrability problems of differential equations are addressed by using the concept of C\mathcal{C}^{\infty}-structure, a recent generalization of the notion of solvable structure. Specifically, the integration procedure associated with C\mathcal{C}^{\infty}-structures is used to integrate to a Lotka-Volterra model and several differential equations that lack sufficient Lie point symmetries and cannot be solved using conventional methods

    Boussinesq Solitons as Propagators of Neural Signals

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    We  consider  certain  approximation for determining the  equation  of motion  for nerve  signals by  using  the  model  of the  lipid  melting  of membranes.   The  nerve  pulses  are  found  to  display nonlinearity and  dispersion  during  the  melting  transition.  In this  simplified model the  nonlinear equation  early  proposed  by  Heimburg  and  coworkers  transformed to  the  well known  integrable Boussinesq  non linear  equation.   Under  specific values of the  parametric space this  system  shows the  existence  of singular  and  regular  soliton  like structures.   After  their  collisions  the  mutual creation  and annihilation (each other)  of nerve signals along the  nerve,  during  their  propagation, has been observed.Keywords: Boussinesq equation,  singular  solitons,  single neurons,  neural  code

    C\mathcal{C}^{\infty}-structures in the integration of involutive distributions

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    For a system of ordinary differential equations (ODEs) or, more generally, an involutive distribution of vector fields, the problem of its integration is considered. Among the many approaches to this problem, solvable structures provide a systematic procedure of integration via Pfaffian equations that are integrable by quadratures. In this paper structures more general than solvable structures (named cinf-structures) are considered. The symmetry condition in the concept of solvable structure is weakened for cinf-structures by requiring their vector fields be just cinf-symmetries. For cinf-structures there is also an integration procedure, but the corresponding Pfaffian equations, although completely integrable, are not necessarily integrable by quadratures. The well-known result on the relationship between integrating factors and Lie point symmetries for first-order ODEs is generalized for cinf-structures and involutive distributions of arbitrary corank by introducing symmetrizing factors. The role of these symmetrizing factors on the integrability by quadratures of the Pfaffian equations associated with the \cinf-structure is also established. Some examples that show how these objects and results can be applied in practice are also presented

    C\mathcal{C}^{\infty}-symmetries of distributions and integrability

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    An extension of the notion of solvable structure for involutive distributions of vector fields is introduced. The new structures are based on a generalization of the concept of symmetry of a distribution of vector fields, inspired in the extension of Lie point symmetries to C\mathcal{C}^{\infty}-symmetries for ODEs developed in the recent years. These new objects, named C\mathcal{C}^{\infty}-structures, play a fundamental role in the integrability of the distribution: the knowledge of a C\mathcal{C}^{\infty}-structure for a corank kk involutive distribution permits to find its integral manifolds by solving kk successive completely integrable Pfaffian equations. These results have important consequences for the integrability of differential equations. In particular, we derive a new procedure to integrate an mmth-order ordinary differential equation by splitting the problem into mm completely integrable Pfaffian equations. This step-by-step integration procedure is applied to integrate completely several equations that cannot be solved by standard procedures

    Programas y recursos disponibles para una visita guiada: El Canal de Castilla

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    Este trabajo Fin de Grado se centra en la búsqueda de programas y recursos que existen en la actualidad para realizar una visita escolar guiada al Canal de Castilla, con el fin de concretar las posibilidades que se ofrecen a escolares de diferentes edades para que puedan conocer y disfrutar de este gran patrimonio histórico y ambiental de una forma guiada a lo largo de su recorrido.El Canal de Castilla es un gran recurso para la educación, dado que permite aprender aspectos relativos de nuestra historia y del entorno que rodea al Canal (elementos de ingeniería, flora y fauna).Una salida resulta altamente beneficioso y gratificante para el alumno, porque a través de un contacto directo va a conocer y entender mejor los contenidos que se le están mostrando en el aula, le permite descubrir otros nuevos, desarrollar sus habilidades sociales y mejorar relaciones existentes con sus compañerosGrado en Educación Primari

    Acacia Horrida (L.) Willd.: refugio de artrópodos benéficos en la costa peruana

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    El huarango (Acacia horrida (L.) Willd., 1806) es una leguminosa arbustiva utilizada como cerco vivo en áreas agrícolas para prevenir la erosión, mejorar la nutrición del suelo y servir, además, como refugio para artrópodos benéficos, contribuyendo así a la sostenibilidad de los agroecosistemas productivos. Por ello, se quiso conocer las especies de artrópodos benéficos asociados a A. horrida en agroecosistemas de la costa centro y sur del Perú. Para ello, se colectó especímenes en cercos vivos de A. horrida cercanos a cultivos de hortalizas de La Molina (Lima), campos de mandarina y palto en Cañete (Lima) y huertos caseros con camote y frutales en Los Aquijes (Ica). Los resultados obtenidos permitieron encontrar en La Molina arañas Salticidae y Argiope sp., insectos depredadores como Harmonia axyridis Pallas, 1773, Cycloneda sanguinea Linnaeus, 1743, Scymnus rubicundus Erichson, 1847 y parasitoides del género Bracon. En Cañete se encontró la araña Gasteracantha cancriformis Linnaeus, 1758, insectos depredadores como C. sanguinea, S. rubicundus, Ceraeochrysa cincta (Schneider, 1851), Allograpta sp., Tachycompilus sp., y parasitoides como Venturia sp., Campoletis sp. Anomalon sinuatum Morley, 1912, subfamilias Cryptinae, Campopleginae (Ichneumonidae), Braconinae, Microgastrinae, Opiinae (Braconidae) y la familia Eulophidae. En Los Aquijes se encontró C. sanguinea, Hippodamia convergens Guérin-Méneville, 1842, Polistes sp. y parasitodes del género Bracon, siendo estos últimos depredados por arañas de la familia Thomisidae. Se concluye que al menos 22 taxa de artrópodos benéficos están asociados a A. horrida como refugio
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