La expansión territorial de Acapulco y el uso inadecuado del suelo, derivado de las políticas de planeación urbana

La estructura urbana de la ciudad y puerto de Acapulco está determinada primordialmente por la actividad turística, dando lugar a un tipo de organización que divide a este centro de población en dos zonas radicalmente diferentes, espacios urbanos con profundas diferencias en calidad de servicios y en densidad de población. Aunado a lo anterior y no menos importante, es la situación orográfica de la ciudad que junto con las acciones habitacionales tanto públicas como privadas han marcado la pauta de la expansión urbana. En sus inicios como centro turístico, la mancha urbana creció a partir del antiguo casco urbano, expandiéndose sobre el litoral costero para usos turísticos y sobre las montañas del anfiteatro para los requerimientos de vivienda de la población residente, marcando desde sus inicios una fuerte segregación del espacio urbano. Las altas tasas de crecimiento de la población que generó el desarrollo de la actividad turística, rebasó la capacidad de las autoridades para atender la demanda de suelo para vivienda que requería la población local por lo que se aplicó la política de regularización de colonias populares previamente invadidas ilegalmente, sin considerar la capacidad y aptitud del suelo para uso urbano, generándose espacios sin servicios y con riesgos de deslaves o inundaciones. En las últimas décadas, el enfoque puramente financiero de las políticas públicas de vivienda para beneficiar al sector inmobiliario, si bien ha generado un importante volumen en la producción en Acapulco, impactan en la absorción física de localidades rurales a la mancha urbana, sobre suelos con problemas de inundación. El presente estudio determina el grado de incidencia de las políticas urbanas en la expansión de la ciudad y por consiguiente de los problemas derivados de la ocupación de suelo en áreas inapropiadas para el uso urbano

CAHRS hrSpectrum (March - April 2003)

HRSpec03_04.pdf: 123 downloads, before Oct. 1, 2020

Searching for stable fullerenes in space with computational chemistry

We report a computational study of the stability and infrared (IR) vibrational spectra of neutral and singly ionised fullerene cages containing between 44 and 70 carbon atoms. The stability is characterised in terms of the standard enthalpy of formation per CC bond, the HOMO-LUMO gap, and the energy required to eliminate a C$_2$ fragment. We compare the simulated IR spectra of these fullerene species to the observed emission spectra of several planetary nebulae (Tc 1, SMP SMC 16, and SMP LMC 56) where strong C$_{60}$ emission has been detected. Although we could not conclusively identify fullerenes other than C$_{60}$ and C$_{70}$, our results point to the possible presence of smaller (44, 50, and 56-atom) cages in those astronomical objects. Observational confirmation of our prediction should become possible when the James Webb Space Telescope comes online.Comment: 11 pages, 13 figures, 1 table. Accepted for publication on MNRA

Estrategia desde la propuesta nacional aulas en paz para contribuir a la convivencia entre los estudiantes del grado s?ptimo dos de la instituci?n educativa Nicanor Velasquez Ort?z del municipio de Ambalema Tolima

75 p. Recurso Electr?nicoEn el nivel secundario en Colombia la mayor?a de los estudiantes presentan dificultades en su vida escolar, este ha sido el mayor reto para ser trabajado en el aula; El programa Aulas en Paz ayuda a los estudiantes para hacer frente a esa situaci?n mediante el uso de diversas estrategias para mejorar las competencias ciudadanas. Esta investigaci?n propone ejecutar algunas de esas estrategias adaptadas a su contexto en la Instituci?n Educativa Nicanor Vel?zquez Ort?z con el fin de mejorar las habilidades sociales y comunicativas de los estudiantes y contribuir al desarrollo de las pr?cticas sociales eficaces para resolver los conflictos de forma democr?tica, reflexiva y pac?fica; esas necesidades se identificaron durante el an?lisis de los documentos institucionales, como el manual de convivencia escolar, observador anecd?tico y el Proyecto Educativo Institucional en el que los principales factores de violencia escolar son las familias disfuncionales y la falta de apoyo de los padres en la vida de los estudiantesIn High school level in Colombia most of the students present difficulties in their school life, this has been the biggest challenge to be worked in the classroom, Aulas en Paz Program helps students to deal with that situation through the use of several strategies to improve citizenship skills. This research proposes implementing at Nicanor Velazquez Ort?z High School some of those strategies adapted to its context in order to improve students social and communication skills and contribute to the development of effective social practices to solve conflicts in a democratic, reflexive and pacific way; those necessities were identified during the analysis of institutional documents like the school coexistence manual, anecdotal observer and the educational institutional project in which the principal factors of school violence are dysfunctional families and the lack of parental support in students' life Keywords: Strategy, competence, classroom peace, social skills, communicative skill

Carbon fibre tips for scanning probe microscopy based on quartz tuning fork force sensors

We report the fabrication and the characterization of carbon fibre tips for their use in combined scanning tunnelling and force microscopy based on piezoelectric quartz tuning fork force sensors. We find that the use of carbon fibre tips results in a minimum impact on the dynamics of quartz tuning fork force sensors yielding a high quality factor and consequently a high force gradient sensitivity. This high force sensitivity in combination with high electrical conductivity and oxidation resistance of carbon fibre tips make them very convenient for combined and simultaneous scanning tunnelling microscopy and atomic force microscopy measurements. Interestingly, these tips are quite robust against occasionally occurring tip crashes. An electrochemical fabrication procedure to etch the tips is presented that produces a sub-100 nm apex radius in a reproducible way which can yield high resolution images.Comment: 14 pages, 10 figure

Boletín oficial de la provincia de León: Boletín oficial de la provincia de León: Número 33 - 1960 febrero 10 (10/02/1960)

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2011-201

Detection of Anomalous Microwave Emission in the Pleiades Reflection Nebula with WMAP and the COSMOSOMAS Experiment

We present evidence for anomalous microwave emission (AME) in the Pleiades reflection nebula, using data from the seven-year release of the Wilkinson Microwave Anisotropy Probe (WMAP) and from the COSMOSOMAS experiment. The flux integrated in a 1-degree radius around R.A.=56.24^{\circ}, Dec.=23.78^{\circ} (J2000) is 2.15 +/- 0.12 Jy at 22.8 GHz, where AME is dominant. COSMOSOMAS data show no significant emission, but allow to set upper limits of 0.94 and 1.58 Jy (99.7% C.L.) respectively at 10.9 and 14.7 GHz, which are crucial to pin down the AME spectrum at these frequencies, and to discard any other emission mechanisms which could have an important contribution to the signal detected at 22.8 GHz. We estimate the expected level of free-free emission from an extinction-corrected H-alpha template, while the thermal dust emission is characterized from infrared DIRBE data and extrapolated to microwave frequencies. When we deduct the contribution from these two components at 22.8 GHz the residual flux, associated with AME, is 2.12 +/- 0.12 Jy (17.7-sigma). The spectral energy distribution from 10 to 60 GHz can be accurately fitted with a model of electric dipole emission from small spinning dust grains distributed in two separated phases of molecular and atomic gas, respectively. The dust emissivity, calculated by correlating the 22.8 GHz data with 100-micron data, is found to be 4.36+/-0.17 muK/MJy/sr, a value that is rather low compared with typical values in dust clouds. The physical properties of the Pleiades nebula indicate that this is indeed a much less opaque object than others were AME has usually been detected. This fact, together with the broad knowledge of the stellar content of this region, provides an excellent testbed for AME characterization in physical conditions different from those generally explored up to now.Comment: Accepted for publication in ApJ. 12 pages, 8 figure

Numerical simulation of EHD flows using Discontinuous Galerkin Finite Element methods

The aim of this paper is to explore the capability of Discontinuous Galerkin Finite Element methods to solve numerically the charge transport equation in EHD convective flows, in both strong and weak injection regimes. These methods are especially suited to treat purely hyperbolic problems, as it is the charge transport equation in most EHD problems. We consider the 2D electroconvective flow between two parallel plates. We compare our com- putations with the analytical results in the hydrostatic regime, the linear and non-linear stability analysis, computing both the electric and velocity fields. The stability of the finite amplitude electroconvection is also anal- ysed. Comparisons are made with computations in the literature obtained with other numerical techniques. The results show that DG-FEM are a very good alternative to simulate numerically EHD convective flows

Boletín oficial de la provincia de León: Boletín oficial de la provincia de León: Número 290 - 1960 diciembre 21 (21/12/1960)

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2011-201