Resonance Zones and Lobe Volumes for Volume-Preserving Maps

We study exact, volume-preserving diffeomorphisms that have heteroclinic connections between a pair of normally hyperbolic invariant manifolds. We develop a general theory of lobes, showing that the lobe volume is given by an integral of a generating form over the primary intersection, a subset of the heteroclinic orbits. Our definition reproduces the classical action formula in the planar, twist map case. For perturbations from a heteroclinic connection, the lobe volume is shown to reduce, to lowest order, to a suitable integral of a Melnikov function.Comment: ams laTeX, 8 figure

Generating Forms for Exact Volume-Preserving Maps

We study the group of volume-preserving diffeomorphisms on a manifold. We develop a general theory of implicit generating forms. Our results generalize the classical formulas for generating functions of symplectic twist maps.Comment: laTeX, 20 pages, 1 figur

Lecturas y relecturas. Ensayos de interpretación simbólica

¿Qué evocan, provocan y convocan los creadores con sus obras? Raúl H. Mora, S.J. prueba respuestas con esta compilación y selección de los artículos, ensayos, conferencias y entrevistas que publicó durante dos décadas en diversas revistas académicas, culturales y políticas, tales como Christus, Envío, Proceso, Renglones y Xipe-Totek. El autor recurre a las diversas escuelas y técnicas de interpretación simbólica para ejercitarse en la crítica de las obras de arte y compartir la experiencia que vivió al adentrarse en el quehacer, la palabra y las imágenes de un numeroso listado de narradores, cantautores, filósofos, poetas y cineastas, quienes en su gran mayoría cultivaron sus oficios en el siglo XX, a excepción de Miguel de Cervantes Saavedra. El carácter celebrativo es uno de los principales detonantes de los 14 textos que conforman este libro: la lamentación por el deceso de Jean–Paul Sartre, el reconocimiento al legado de Alfonso Reyes, la celebración de la gesta nicaragüense en las voces de Ernesto Cardenal, Gioconda Belli y los hermanos Luis Enrique y Carlos Mejía Godoy, la conquista de nuestra identidad latinoamericana, el descubrimiento de la vida plena en la literatura contemporánea, el desenfreno quijotesco para rehacer la esperanza y el festejo por este nuevo milenio.ITESO, A.C

Symmetry Reduction by Lifting for Maps

We study diffeomorphisms that have one-parameter families of continuous symmetries. For general maps, in contrast to the symplectic case, existence of a symmetry no longer implies existence of an invariant. Conversely, a map with an invariant need not have a symmetry. We show that when a symmetry flow has a global Poincar\'{e} section there are coordinates in which the map takes a reduced, skew-product form, and hence allows for reduction of dimensionality. We show that the reduction of a volume-preserving map again is volume preserving. Finally we sharpen the Noether theorem for symplectic maps. A number of illustrative examples are discussed and the method is compared with traditional reduction techniques.Comment: laTeX, 31 pages, 5 figure

Nadando contra corriente

En este texto se analiza la película Rompiendo las olas, del cineasta danés Lars von Trier. Se valoran tres puntos de esta obra: primero, las referencias que se hacen a Dios y los diferentes símbolos que remiten a Él o a la religión, así como el papel que juega la Iglesia en la comunidad, las diferentes concepciones del matrimonio, etcétera. Luego se exploran las actitudes discriminatorias para con las mujeres, tanto de los mismos personajes como de la Iglesia y, por último, se revisa la relación entre sexo y religión en el filme

Canonical Melnikov theory for diffeomorphisms

We study perturbations of diffeomorphisms that have a saddle connection between a pair of normally hyperbolic invariant manifolds. We develop a first-order deformation calculus for invariant manifolds and show that a generalized Melnikov function or Melnikov displacement can be written in a canonical way. This function is defined to be a section of the normal bundle of the saddle connection. We show how our definition reproduces the classical methods of Poincar\'{e} and Melnikov and specializes to methods previously used for exact symplectic and volume-preserving maps. We use the method to detect the transverse intersection of stable and unstable manifolds and relate this intersection to the set of zeros of the Melnikov displacement.Comment: laTeX, 31 pages, 3 figure

Quadratic Volume Preserving Maps

We study quadratic, volume preserving diffeomorphisms whose inverse is also quadratic. Such maps generalize the Henon area preserving map and the family of symplectic quadratic maps studied by Moser. In particular, we investigate a family of quadratic volume preserving maps in three space for which we find a normal form and study invariant sets. We also give an alternative proof of a theorem by Moser classifying quadratic symplectic maps.Comment: Ams LaTeX file with 4 figures (figure 2 is gif, the others are ps

Indicadores de la modernización mexicana

Se sostiene aquí la hipótesis de que el proyecto neoliberal mexicano perjudica a las grandes mayorías y favorece fundamentalmente a los ya privilegiados, al menos a corto y mediano plazos. La obra presenta el marco internacional en que se está produciendo la modernización nacional; informa sobre algunos indicadores de la modernización económica a nivel macro; reflexiona sobre los procesos de reforma educativa que el modelo exige, promueve e impone; habla del papel de los medios de comunicación en el proceso y aterriza las consecuencias de la modernización en el caso de los obreros e indígenas.ITESO, A.C.Centro de Reflexión y Acción SocialCentro de Reflexión Teológic

In vitro gastrointestinal digestion of microencapsulated extracts of Flourensia cernua, F. microphylla, and F. retinophylla

Recently, some species of the genus Flourensia have been identified by their potential health effects (e.g. anti-inflammatory and apoptotic). Encapsulation of plant extracts is a process that can allow an adequate dosage administration, as well as to protect bioactive compounds and improve their controlled release in the gastrointestinal (GI) system. Therefore, the aims of this work were: to microencapsulate the ethanol extracts of F. cernua, F. microphylla, and F. retinophylla; and to evaluate the controlled release of the microencapsuled extracts in an in vitro GI system. Leaves of Flourensia spp. were collected in wild sites of Coahuila State, and the ethanol extracts were obtained by the Soxhlet method. The encapsulation was performed by the gelation technique, using alginate. The microcapsules formed were characterized in terms of total phenol content (Folin-Ciocalteu method), antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic) diammonium acid (ABTS), and the ferric reducing antioxidant power (FRAP) assays, scanning electron microscopy (SEM), and thermal analysis, and in vitro GI digestion. The microcapsules were found to have spherical-shape and a micro-scale dimension in the range of 2.168.8??m. Also, the built of microcapsules was confirmed by the appearance of an exothermic peak centered at 600?°C in the DSC analysis. F. microphylla noted for its strong antioxidant activity, even in its encapsulated form. In the gastric system the extracts of fresh microcapsules were released from 7.7% to 14.5%, while values of 26.5% to 53.3% were observed for those dried. For the intestinal system, the higher release was observed for dried microcapsules (59.9% to 78.4%) than for those fresh (26.3% to 30.2%). Thus, it was demonstrated that the alginate microcapsule protected the extracts until they were delivered to the target site in the GI model, and this effect was better with the dried microcapsules of Flourensia spp. This study would set the guide for the application of Flourensia spp. extracts in order to take advantage of their benefits to human health.Author G.N. Puente Romero thanks Mexican Science and Technology Council (CONACYT, Mexico) for MSc fellowship support. Authors would like to thank to María Guadalupe Moreno Esquivel, Edith E. Chaires Colunga, Olga L. Solís Hernández, and M. Leticia Rodríguez González of the Phytochemistry Laboratory from Universidad Autónoma Agraria Antonio Narro, for their support in the lab experiments.info:eu-repo/semantics/publishedVersio