Transmission in waveguides with compositional and structural disorder: experimental effects of disorder cross-correlations

We analyse the single-mode transmission of microwaves in a guide with internal random structure. The waveguide contains scatterers characterised by random heights and positions, corresponding to compositional and structural disorder. We measure the effects of cross-correlations between two kinds of disorder, showing how they enhance or attenuate the experimentally found transmission gaps generated by long-range self-correlations. The results agree with the theoretical predictions obtained for the aperiodic Kronig-Penney model and prove that self- and cross-correlations have relevant effects also in finite disordered samples of small size.Comment: 15 pages, 8 figure

Electronic states and transport properties in the Kronig-Penney model with correlated compositional and structural disorder

We study the structure of the electronic states and the transport properties of a Kronig-Penney model with weak compositional and structural disorder. Using a perturbative approach we obtain an analytical expression for the localisation length which is valid for disorder with arbitrary correlations. We show how to generate disorder with self- and cross-correlations and we analyse both the known delocalisation effects of the long-range self-correlations and new effects produced by cross-correlations. We finally discuss how both kinds of correlations alter the transport properties in Kronig-Penney models of finite size.Comment: 23 pages, 5 figure

La preservación del registro arqueomagnético en estructuras de combustión experimentales con 2 y 5 años de antigüedad

Trabajo presentado en: Magiber XI, 4-7 de septiembre de 2019, Condeixa a NovaJCYL-EFRD project BU235P18 and the MINECO-EFRD projects HAR2015-68321-P and CGL2016-77560, as well as the ERC Consolidator Grant project PALEOCHAR (648871

Análisis financiero en busca de rentabilidad privada en empresas constructoras. caso de análisis Altozano, Morelia, Michoacán, México

This research adderesses the issue of profitability from the discipline of economics, understanding it as a notion that applies to any economic action in which material, human and financial means are mobilized in order to obtanin certain results (De la Hoz Suarez et. Al., 2008). When this is positive, the company earns money (profit) and has fulfilled its objective; if this result is negative, the product in question is making a loss, so it is necessary to reviex the strategies, and if no corrective action can be implemented, the product should be discontinued. An analysis is made of the profitability of the construction companies that participated in the construction of housing in the commercial zone of Altozano Morelia. The sample for the study corresponds to 10 companies, from which financial and construction project that participated in the construction of housing in the commercial zone of Altozano Morelia. The sample for the study corresponds to 10 companies, from which financial and construction project information was obtained. At the same time, it is possible to determine to what extent the construction and real estate companies can be profitable, this is established from a financial calculation that determines the amount of houses that must be sold to cover their costs, and at the same time improve their competitive advantage base don financial information.Esta investigación aborda el tema de la rentabilidad desde la disciplina de la economía, entendiéndola como una noción que se aplica a toda acción económica en la que se movilizan medios materiales, humanos y financieros con el fin de obtener ciertos resultados (De la Hoz Suarez et al., 2008). Cuando esta resulta positiva la empresa gana dinero (utilidad) y ha cumplido su objetivo, si este resultado es negativo, el producto en cuestión está dando pérdida, por lo que es necesario revisar las estrategias, y en caso de que no se pueda implementar ningún correctivo, el producto debe ser descontinuado. Se hace un análisis de la rentabilidad de las empresas constructoras que participaron en la edificación de vivienda en la zona comercial de Altozano Morelia. La muestra para el estudio corresponde a 10 empresas, de las que se obtuvo información financiera y de proyecto de construcción. Al mismo tiempo, se logra determinar hasta qué punto las empresas constructoras e inmobiliarias pueden ser rentables, esto se establece a partir de un cálculo financiero que determina la cantidad de viviendas que se deben vender para cubrir sus costos, y a su vez mejorar su ventaja competitiva en base a información financiera

Gain- or loss-induced localization in one-dimensional PT-symmetric tight-binding models

We investigate the properties of parity-time (PT)-symmetric tight-binding models by considering both bounded and unbounded models. For the bounded case, we obtain closed form expressions for the corresponding energy spectra and we analyze the structure of eigenstates as well as their dependence on the gain or loss contrast parameter. For unbounded PT lattices, we explore their scattering properties through the development of analytical models. Based on our approach we identify a mechanism that is responsible to the emergence of localized states that are entirely due to the presence of gain and loss. The derived expressions for the transmission and reflection coefficients allow one to better understand the role of PT symmetry in energy transport problems occurring in such PT-symmetric tight-binding settings. Our analytical results are further exemplified via pertinent examples

Anomalous properties of the Kronig-Penney model with compositional and structural disorder

We study the localization properties of the eigenstates in the Kronig-Penney model with weak compositional and structural disorder. The main result is an expression for the localization length that is valid for any kind of self- and inter-correlations of the two types of disorder. We show that the interplay between compositional and structural disorder can result in anomalous localization.Comment: 11 pages, no figur

It's getting hot in here – Microcontextual study of a potential pit hearth at the Middle Paleolithic site of El Salt, Spain

By studying combustion structures, which conceal information about anthropogenic activity, we might learn about their makers. This is especially important for remote time periods like the Middle Paleolithic, whose archaeological record comprises numerous combustion structures. The majority of these are simple, flat, open hearths, although a small number of features situated in pit-like depressions have been recorded. Given that hearths built on a flat surface can result in pit-like color alteration of the underlying sediment, accurate identification of pit hearths is a crucial step prior to behavioral interpretation. Here we present a comprehensive study of a possible pit hearth from the Middle Paleolithic site of El Salt, Spain, using a microcontextual approach combining micromorphology, lipid biomarker analysis, archaeomagnetism and zooarchaeology. This pit hearth involves a true depression containing a thick plant ash deposit. It reached very high temperatures, possibly multiple burning events and long combustion times. Morphologically distinct combustion structures in a single archaeological context may indicate different functions and thus a diverse fire technology, pointing to Neanderthal behavioral variability.ERC Consolidator Grant project PALEOCHAR – 648871 https://erc.europa.eu/funding/consolidator-grants, I + D Project HAR2008-06117/HIST, HAR2015-68321-P (MINECO-FEDER/UE), and the Cultural Heritage Department of the Valencia Government and the Archaeological Museum Camil Visedo of Alcoy, under the direction of Professor Bertila Galván of Universidad de La Laguna, Junta de Castilla y León (project BU235P18), the European Fund for Economic and Regional Development (EFRD) and the project PID2019-105796 GB-I00 of the Agencia Estatal de Investigación (AEI/10.13039/501100011033

“PROCESOS DE LOCALIZACIÓN Y TRANSPORTE ANÓMALOS EN EL MODELO DE KRONIG-PENNEY”

En 1928 Felix Bloch publicó un teorema muy importante sobre la función de onda de una partícula cuántica en un potencial periódico [1]. Este teorema dice que la solución de la ecuación de Schrödinger con un potencial periódico toma la forma de ondas planas moduladas con la periodicidad de la red; por lo que los estados electrónicos de todo sistema cristalino (sistema ordenado) son estados extendidos. Tiempo después surgió la interrogante de cómo serían los estados electrónicos en un sistema desordenado; la respuesta la dió P. W. Anderson en 1958 mostrando que los electrónes en muestras desordenadas pueden quedar confinados en regiones limitadas del espacio [2]. A este fenómeno se le llamó localización de Anderson. En los años sesenta el estudio de la localización de Anderson se enfocó en muestras totalmente aleatorias, o sea muestras carentes de cualquier tipo de correlación. Un resultado muy importante que se obtuvo de estos trabajos fue haber demostrado que para los sistemas unidimensionales totalmente desordenados los electrones se localizan exponencialmente sin importar que tan débil sea el desorden [3], a diferencia de lo que pasa en los modelos desordenados tridimensionales donde los electrones están localizados sí la intensidad del desorden es suficientemente fuerte, si no los estados electrónicos son extendidos. Estos resultados engendraron el convencimiento generalizado que en las cadenas unidimensionales no existen estados extendidos y, consecuentemente, que no puede producirse una transición metal-aislante análoga a la que ocurre en muestras 3D cuando la intensidad del desorden rebasa un umbral crítico. En los últimos años el estudio de los sistemas unidimensionales con desorden correlacionado se ha desarrollado rápidamente