Chain Homotopies for Object Topological Representations

This paper presents a set of tools to compute topological information of simplicial complexes, tools that are applicable to extract topological information from digital pictures. A simplicial complex is encoded in a (non-unique) algebraic-topological format called AM-model. An AM-model for a given object K is determined by a concrete chain homotopy and it provides, in particular, integer (co)homology generators of K and representative (co)cycles of these generators. An algorithm for computing an AM-model and the cohomological invariant HB1 (derived from the rank of the cohomology ring) with integer coefficients for a finite simplicial complex in any dimension is designed here. A concept of generators which are "nicely" representative cycles is also presented. Moreover, we extend the definition of AM-models to 3D binary digital images and we design algorithms to update the AM-model information after voxel set operations (union, intersection, difference and inverse)

Ballistic resistivity in aluminum nanocontacts

One of the major industrial challenges is to profit from some fascinating physical features present at the nanoscale. The production of dissipationless nanoswitches (or nanocontacts) is one of such attractive applications. Nevertheless, the lack of knowledge of the real efficiency of electronic ballistic/non dissipative transport limits future innovations. For multi-valent metallic nanosystems -where several transport channels per atom are involved- the only experimental technique available for statistical transport characterization is the conductance histogram. Unfortunately its interpretation is difficult because transport and mechanical properties are intrinsically interlaced. We perform a representative series of semiclassical molecular dynamics simulations of aluminum nanocontact breakages, coupled to full quantum conductance calculations, and put in evidence a linear relationship between the conductance and the contact minimum cross-section for the geometrically favored aluminum nanocontact configurations. Valid in a broad range of conductance values, such relation allows the definition of a transport parameter for nanomaterials, that represents the novel concept of ballistic resistivity

Ammonia or methanol would enable subsurface liquid water in the Martian South Pole

The notion of liquid water beneath the ice layer at the south polar layered deposits of Mars is an interesting possibility given the implications for astrobiology, and possible human habitation. A body of liquid water located at a depth of 1.5 km has been inferred from radar data in the South Polar Cap. However, the high temperatures that would facilitate the existence of liquid water or brine at that depth are not consistent with estimations of heat flow that are based on the lithosphere's flexure. Attempts to reconcile both issues have been inconclusive or otherwise unsuccessful. Here, we analyse the possible role of subsurface ammonia and methanol in maintaining water in a liquid state at subsurface temperatures that are compatible with the lithosphere strength. Our results indicate that the presence of these compounds at the base of the south polar layered deposits can reconcile the existence of liquid water with previous estimations of surface heat flow

Precipitation trends and their relationship with El Niño Oceanic Index. The case of the Mixteca Region, Mexico

[EN] The occurrence of droughts is a permanent concern in arid and semi-arid zones, especially for socially vulnerable ones such as the Mixteca Region in Mexico, a condition that can be aggravated as climate change scenarios predicts. The general circulation models do not allow forecasting precipitation conditions at regional scales, so it is necessary to study local climate behavior and trends. Determining the relationship between local climate and large-scale phenomena, such as El Niño / La Niña events, is relevant to set up prevention measures. This article analyzes the precipitation trends in the Mixteca Region of Mexico, determines the presence of a statistically significant trend in observed decrease in precipitation, and analyzes the relationship between precipitation conditions in the zone and the Ocean Niño Index. It is shown that there is a statistically significant trend of decreasing precipitation, and it is found that there is a correlation between the El Niño Oceanic Index and the conditions of extreme precipitation -humidity or drought- in the region.[ES] La ocurrencia de sequías es una preocupación constante en zonas áridas y semiáridas, especialmente cuando se trata de regiones socialmente vulnerables como es el caso de la Región Mixteca en México, condición que puede agravarse según se anticipa de los escenarios de cambio climático. Los modelos de circulación general no permiten prever las condiciones de precipitación en escalas regionales, por lo que se hace necesario el estudio de las tendencias y comportamientos climáticos locales. Determinar la relación entre el clima local y fenómenos de gran escala, como los eventos El Niño/La Niña, es de relevancia para establecer medidas de prevención. En este artículo se analiza la tendencia de la precipitación en la región Mixteca de México, se determina la presencia de una tendencia estadísticamente significativa a la disminución en la precipitación, y se analiza la relación entre las condiciones de precipitación en la zona y el Índice Oceánico El Niño. Se muestra que existe una tendencia estadísticamente significativa de disminución de la precipitación, y se encuentra que existe una correlación entre el índice Oceánico El Niño y las condiciones de precipitación extrema -humedad o sequía- en la región.Martínez-Austria, PF.; Díaz-Jiménez, D. (2018). Tendencias de la precipitación y su relación con el Índice Oceánico El Niño. El caso de la Región Mixteca, México. Ingeniería del Agua. 22(1):1-14. doi:10.4995/ia.2018.7779SWORD114221Ahmad, I., Tang, D., Wang, T.F., Wang, M., Wagan, B. 2015. Precipitation trends over time using Mann-Kendall and Spearman's Rho tests in Swat River Basin, Pakistan. Advances in Meteorology. Vol. 2015. https://doi.org/10.1155/2015/431860Calahorrano, J., Manazno, M., Gualli, D., Silva, F., Audelo, M., Tingo, J. 2017. Análisis de tendencia en la precipitación anual (1964-2015) en la cuenca del Pastaza. Ecuador. Agua LAC, 9(2), Septiembre 2017, 73-84.Cerano Paredes, J Villanueva Díaz, J., Valdez Cepeda R. D., Méndez González, J., Constante V. 2011. Reconstructed droughts in the last 600 years for northeastern Mexico. Revista Mexicana de Ciencias Agrícolas, 2(2), 235-249.CONAGUA. 2017. Monitor de Sequía - SPI. Último acceso: 7 de Junio de 2017. Disponible en http://smn.cna.gob.mx/es/climatologia/monitor-de-sequia/spi.Florescano, E. 2000. Breve historia de la sequía en México. Ciudad de México, Distrito Federal: Consejo Nacional para la Cultura y las Artes.Goklany, I. M. 2009. Deaths and death rates from extreme weather events: 1900-2008. Journal of American Physicians and Surgeons, 14(4), 102-109.Hayes, M., Svoboda, M., Wall, N., Widhalm, M. 2011. The Lincoln declaration on drought indices. American Meterological Society, April, 485-488. https://doi.org/10.1175/2010BAMS3103.1Hoeppe, P. 2016. Trends in weather related disasters -Consequences for insurers and society. Weather and Climate Extremes, 11, 70-79. https://doi.org/10.1016/j.wace.2015.10.002IICA. 2016. El Niño en la agricultura de las Américas. Boletín Técnico 2016. San José de Costa Rica: Instituto Interamericano de Cooperación para la Agricultura (IICA)-Euroclima.IMTA - SEMARNAT. 2013. Eric III . Eric III Extractor Rápido de Información Climatológica. Versión 3.2. Jiutepec, Morelos: Instituto Mexicano de Tecnología del Agua.INECC. 2016. Escenarios de cambio climático. INECC Cambio Climático. 13 de Noviembre. Último acceso: 7 de Junio de 2017. http://escenarios.inecc.gob.mx/.IPCC. 2007. Climate 2007: Impacts, Adaptation and Vulnerability. O Perry, O. Canziani, P. Palutikof y H.C. van del Linden. (Eds.) Cambrigde: Cambridge University Press.IPCC. 2012. Gestión de los riesgos de fenómenos extremos y desastres naturales para mejorar la adaptación al cambio climático. Informe Especial, Grupo Intergubernamental de Expertos sobre el Cambio Climático. 2013. Climate Change.IPCC. 2013. The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the IPCC. Cambridge: Cambridge University Press.IPCC. 2014. Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernamental Panel on Climate Change. Geneva.Lloyd-Hughes, B., Saunders, M. A. 2002. A drought climatology for Europe. International Journal of Climatology, 22(13), 1571-1592. https://doi.org/10.1002/joc.846Maca, P., Pech, P. 2016. Forecasting SPEI and SPI Drought Indices Using the Integrated Artificial Neural Networks. Computational Inteligence and Neuroscience, 17. https://doi.org/10.1155/2016/3868519Martínez-Austria, P. F., Bandala E. R. 2017. Temperature and heat-related mortality trends in the Sonoran and Mojave desert region. Atmosphere, 8(53). https://doi.org/10.3390/atmos8030053Marcos Valiente, O. 2001. Sequía: definiciones, tipologías y métodos de cuantificación. Investigaciones geográficas, 26. Último acceso: 10 de enero de 2018. Disponible en http://www.redalyc.org/articulo.oa?id=17602604.Nation Master. 2017. Economy, Population below poverty line. Centro masivo de datos en Internet. Consultado el 14 de diciembre de 2017. Disponible en http://www.nationmaster.com/country-info/stats/Economy/Population-below-poverty-line#2010National Weather Service. 2017. Cold & Warm Episodes by Season. 5 de 6. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears_1971-2000_climo.shtml.Ortega Gaucin, D. 2013. Impacto de las sequías en Nuevo León. Ciencia UANL (Universidad Autónoma de Nuevo León), 63, 8-14.Otkin, J. A., Anderson, M. C., Hain, C., Svoboda M. 2015 Using temporal changes in drought indices to generate probabilistic drought intensification forecast. Journal of Hydrometeorology (American Meteorology Society) 16, 88-105. https://doi.org/10.1175/JHM-D-14-0064.1Peterson, Larry C., Gerald, H. H. 2005. Climate and the collapse of Maya civillization. American Scientist, 93, 322-329. https://doi.org/10.1511/2005.54.968Randall, D. A., Word, R. A. 2007. Climate models and their evaluation. En IPCC, Climate 2007: Impacts, Adaptation and Vulnerability, 589-662. Cambridge: Cambridge University Press.Rojas, O., Li, Y., Cumani, R. 2014. Understanding the drought impact of El Niño on the global agricultural areas: an assessment using FAO's Agricultural Stress Index. Rome: FAO.Salinas Prieto, J. A., Colorado Ruiz, G., Maya Magaña, M. E. 2015. Escenarios de Cambio Climático para México. En Atlas de vulnerabilidad hídrica de México ante el cambio climático, 41-70. 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The Presence of Precursors of Benign Pre-B Lymphoblasts (Hematogones) in the Bone Marrow of a Paediatric Patient with Cytomegalovirus Infection

Hematogones are normal B-lymphoid precursors that multiply in the bone marrow of small children and of adults with ferropenic anaemia, neuroblastoma or idiopathic thrombocytopenic purpura. They are not normally found in peripheral blood, and the immunophenotype is virtually indistinguishable from that of B lymphoblasts. We discuss the case of a 3-month infant with an active cytomegalovirus infection, with hepatitis and pancytopenia associated with 13% hematogones in the bone marrow

Evaluación del comportamiento mecánico de mezclas asfálticas templadas con 100 % de material reciclado

The use of Half Warm Mixes with high Reclaimed Asphalt content (HWMRA) has the potential to generate significant environmental advantages such as the reduction in consumption of natural resources and the emission of gases into the atmosphere. This paper therefore focuses on demonstrating the viability of using these types of mixes in wearing courses. For this purpose, an HWMRA with 70 % and 100 % Reclaimed Asphalt Pavement (RAP) and emulsion were designed in the laboratory. The performance of the mixes was then assessed and compared with that of conventional Hot Mix Asphalt. In a second stage, the mixes were manufactured in-plant, and laid and compacted in an Accelerated Pavement Test track. The cores were then extracted and tested for stiffness modulus and resistance to fatigue. The results from the tests conducted with both the laboratory specimens and the cores showed that the performance of HWMRA is comparable to that of HMA. These findings encourage greater confidence in promoting the use of these types of sustainable asphalt mixes.La utilización de mezclas asfálticas templadas con alto contenido de asfalto reciclado (HWMRA) conlleva ventajas medioambientales como la reducción del consumo de recursos naturales y la emisión de gases a la atmósfera. Este artículo se centra en mostrar la viabilidad de este tipo de mezclas para capas de rodadura. Para ello, se diseñaron mezclas HWMRA con 70 % y 100 % de asfalto reciclado en el laboratorio y se evaluó y comparó su comportamiento con una mezcla caliente convencional. En una segunda etapa, las mezclas fueron fabricadas en planta, extendidas y compactadas en una pista de ensayo acelerado de pavimentos. A continuación, se extrajeron testigos y se ensayaron para conocer su módulo de rigidez y resistencia a fatiga. Tanto los resultados de laboratorio como tras la fabricación en planta y puesta en obra mostraron que el comportamiento de mezclas HWMRA es comparable al de mezclas calientes convencionales. Dicha conclusión puede aportar confianza a este tipo de mezclas sostenibles promoviendo su mayor utilización