Stability fem analysis of rock masses modeling pattern of joints

In the south of the city of Morelia, Mexico, there is a geological normal fault denominated "La Paloma". It has a height of 180 m and has limited the growth of the city. To improve the connectivity of the city, an urban road is building and it includes the digging of a tunnel that goes through this fault. Due to the presence of an ancient landslide in the exit tunnel, it is imperative to verify the stability of a slope in this zone. The geological structures founded “in situ” make complex the stability analyses, but the used of more realistic representation helps to understand the mechanism of failure. The data collected in geotechnical explorations helped to construct several models for slope stability analysis. Rocks and soils were identified in the interest area. In this way, an elastoplastic Finite Element Analysis (FEA) was carried out to verify the slope stability, considering a strength reduction by a safety factor. Stability was revised in static and seismic conditions. The rock structure is represented by using the Modified Hoek and Brown constitutive model and patterns of the joints with a Mohr-Coulomb constitutive model. The fragments of rock were emulated with joint patterns according to the geologic structure. The slope stability results show a stable slope considering static and pseudo-static FEA analysis. The failure mechanism could be appreciated with the slope stability analysis realized

Ontogeny and structure of the acervulate partial inflorescence in Hyophorbe lagenicaulis (Arecaceae; Arecoideae)

Background and Aims The palm tribe Chamaedoreeae displays flowers arranged in a complex partial inflorescence called an acervulus. This type of partial inflorescence has so far not been reported elsewhere in the largest palm subfamily Arecoideae, which is traditionally characterized by flowers predominantly arranged in triads of one central female and two lateral male flowers. The ontogenetic basis of the acervulus is as yet unknown and its structural diversity throughout the genera of the Chamaedoreeae poorly recorded. This study aims to provide critical information on these aspects. Methods Developmental series and mature inflorescences were sampled from plants cultivated in international botanical gardens and wild populations. The main techniques employed included scanning electronic microscopy and serial anatomical sectioning of resin-embedded fragments of rachillae. Key Results Inflorescence ontogeny in Hyophorbe lagenicaulis demonstrates that the acervulus and the inflorescence rachilla form a condensed and cymose branching system resembling a coenosome. Syndesmy results from a combined process of rapid development and adnation, without or with reduced axis elongation. Acervulus diversity in the ten taxa of the Chamaedoreeae studied is displayed at the level of their positioning within the inflorescence, their arrangement, the number of floral buds and their sexual expression. Conclusions The results show that a more general definition of the type of partial inflorescence observed within the large subfamily Arecoideae would correspond to a cyme rather than to a floral triad. In spite of their common cymose architecture, the floral triad and the acervulus present differences with respect to the number and arrangement of floral buds, the superficial pattern of development and sexual expressio

Renewable energy research progress in Mexico: a review

Mexico ranks 9th in the world in crude oil reserves, 4th in natural gas reserves in America and it is also highly rich in renewable energy sources (solar, wind, biomasss, hydropower and geothermal). However, the potential of this type of energy has not been fully exploited. Hydropower is the renewable energy source with the highest installed capacity within the country (11,603 MW), while geothermal power capacity (958 MW) makes Mexico to be ranked 4th in the use of this energy worldwide. Wind energy potential is concentrated in five different zones, mainly in the state of Oaxaca, and solar energy has a high potential due to Mexico's ideal location in the so called Solar Belt. Biomass energy has the highest potential (2635 to 3771 PJ/year) and has been the subject of the highest number of research publications in the country during the last 30 years (1982-2012). Universidad Nacional Autonoma de Mexico has led research publications in hydropower, wind, solar and biomass energy and Instituto de Investigaciones Electricas in geothermal energy during this period. According to the General Law for Climate Change the country has set the goal of generating 35% of its energy needs from renewable sources by 2024. This paper presents an overview of the renewable energy options available in Mexico, current status, main positive results to date and future potential. It also analyses barriers hindering improvements and proposes pertinent solutions. © 2014 The Authors

The communications strategy via Twitter of Nayib Bukele: the millennial president of El Salvador

On June 1, 2019, Nayib Bukele assumed the presidency of the Republic of El Salvador, becoming the youngest leader in the democratic history of this Central American country. His communications strategy on Twitter attracted the attention of the international press, because of a peculiar way of using this tool to tweet direct orders to his governmental team through Twitter, with many of his messages having a humoristic lilt. Observing this way of communicating prompted a wish to investigate the communications strategy of President Nayib Bukele on Twitter. Online tools, such as Twitonomy and Vicinitas, were used for the quantitative analysis of the account over the first two weeks of his presidency. Additionally, an in-depth interview was held with the communications secretary of the government of El Salvador, Sofía Medina. Finally, a broad description of the economic and social situation of the country helps understand the relevance of the data obtained from the analysis, emphasizing the scarce access to both information technology and social networks among the inhabitants.El 1 de junio de 2019 Nayib Bukele tomó posesión como presidente de la República de El Salvador, convirtiéndose en el mandatario más joven en la historia de la democracia de este país de Centroamérica. Su estrategia de comunicación en Twitter llamó la atención de la prensa internacional por una peculiar forma de utilizar esta herramienta, con órdenes directas a su equipo de gobierno a través de Twitter y un tono humorístico en muchos de sus mensajes. Con la observación de este hecho surge la inquietud por investigar la estrategia de comunicación en Twitter del presidente Nayib Bukele. Para el análisis cuantitativo realizado a la cuenta @Nayibbukele durante la primera quincena de gestión se han empleado herramientas online como Twitonomy y Vicinitas. Como complemento, para la interpretación de los resultados obtenidos se ha elaborado una entrevista en profundidad con la responsable de la secretaría de comunicaciones del Gobierno de El Salvador, Sofía Medina. Finalmente, para comprender la relevancia de los datos obtenidos en el análisis, se realiza una amplia descripción de la situación económica y social del país, haciendo énfasis en la falta de acceso a las tecnologías de la información y a las redes sociales por parte de los habitantes

Hypoxic pre-conditioning increases the infiltration of endothelial cells into scaffolds for dermal regeneration pre-seeded with mesenchymal stem cells.

Many therapies using mesenchymal stem cells (MSC) rely on their ability to produce and release paracrine signals with chemotactic and pro-angiogenic activity. These characteristics, however, are mostly studied under standard in vitro culture conditions. In contrast, various novel cell-based therapies imply pre-seeding MSC into bio-artificial scaffolds. Here we describe human bone marrow-derived MSC seeded in Integra matrices, a common type of scaffold for dermal regeneration (SDR). We show and measured the distribution of MSC within the SDR, where cells clearly establish physical interactions with the scaffold, exhibiting constant metabolic activity for at least 15 days. In the SDR, MSC secrete VEGF and SDF-1α and induce transwell migration of CD34(+) hematopoietic/endothelial progenitor cells, which is inhibited in the presence of a CXCR4/SDF-1α antagonist. MSC in SDR respond to hypoxia by altering levels of angiogenic signals such as Angiogenin, Serpin-1, uPA, and IL-8. Finally, we show that MSC-containing SDR that have been pre-incubated in hypoxia show higher infiltration of endothelial cells after implantation into immune deficient mice. Our data show that MSC are fully functional ex vivo when implanted into SDR. In addition, our results strongly support the notion of hypoxic pre-conditioning MSC-containing SDR, in order to promote angiogenesis in the wounds

Electron-positron pair creation in the superposition of two oscillating electric field pulses with largely different frequency, duration and relative positioning

Production of electron-positron pairs in two oscillating strong electric field pulses with largely different frequencies and durations is considered. In a first scenario, the influence of a low-frequency background field on pair production by a short main pulse of high frequency is analyzed. The background field is shown to cause characteristic modifications of the momentum spectra of created particles which, in turn, may be used for imaging of the background pulse. In a second scenario, an ultrashort, relatively weak assisting pulse is superimposed onto a strong main pulse. By studying the dependence of the pair production on the field parameters it is shown that duration and relative position of the ultrashort pulse modify the momentum spectra of produced particles in a distinctive way. Both scenarios enable, moreover, to extract partial information about the time periods when pairs with certain momenta are produced predominantly.Comment: 10 pages, 9 figure

La historia mundial y sus implicaciones en Colima

Las reformas económicas ejecutadas desde hace más de quince años en América Latina han modificado sustancialmente las historias de carácter local, regional y nacional, como resultado del comercio mundial, las transnacionales, la circulación de información, el movimiento de personas. Estos procesos traspasan fronteras y modifican el entorno y la historia de las entidades. El propósito del trabajo es presentar la manera en que México se ve afectado, en particular el estado de Colima, por su papel de mediación entre Asia Pacifico y Estados Unidos en el marco del nuevo orden mundial.México; Colima; Economía internacional; Globalización; Desarrollo regional; Regionalización

Para asombrarse y aprender

Este trabajo presenta la fundamentación, diseño y resultados de un proyecto realizado en el marco de un programa institucional en la UNAM, relacionado con la innovación de la enseñanza experimental. Como producto de este proyecto se elaboró un libro con 30 experimentos de aula dirigidos a profesores de los niveles bachillerato y universitario. Los experimentos elaborados presentan propuestas experimentales novedosas que nos permitan reconceptualizar y diversificar el trabajo práctico

Nuevo método para acelerar la curación de la enfermedad de Perthes

Se presenta el caso de un paciente de 13 años de edad, con el diagnóstico de enfermedad de Perthes avanzada, atendido en el servicio de Ortopedia y Traumatología del Hospital Universitario Celia Sánchez Manduley, en el que se empleó por primera vez el tratamiento quirúrgico convencional asociado al empleo de la oxigenación hiperbárica. La evolución del paciente fue satisfactoria, la nueva combinación de tratamientos, logró reducir el período de evolución de la enfermedad en seis meses.A case of 13 years old patient with advanced Perthes disease is presented. The child was admitted to the orthopedics and traumathology service of the University Hospital Celia Sánchez Manduley. Surgical treatment was associated to hiperbaric oxynation therapy. The patient's outcome was satisfactory. The new treatment combination was able to reduce the evolution's period of disease in six months