Ancient tin production: Slags from the Iron Age Carvalhelhos hillfort (NW Iberian Peninsula)

Provenance and production of tin in the Ancient World has since long been a major topic of discussion among archaeologists. In Western Europe, where significant tin ore (cassiterite) deposits are known, only a few remains of ancient tin production, such as tin slags, have been detected. In the present work, elemental and microstructural analyses by WDXRF, SEM-EDS and XRD were performed on recently recognised tin slags from the Iron Age Carvalhelhos hillfort located in NW Iberia, a territory that represents the largest extension with tin mineralisation in Western Europe. Elemental and microstructural characterisation of cassiterite collected in a pilot field survey in the region of the hillfort are presented and discussed, as well as two ceramic fragments that could be part of a smelting structure and an iron slag from the settlement. Results show that the tin slags have variable but high contents in Sn, similarly to Pre-Medieval tin slags found in other Western European areas, but also high contents of Ta and Nb, which specifically distinguish them from other tin slags, such as those found in SW Britain. Tin ores from the hillfort region frequently have Ta and Nb in cassiterite solid solution or as inclusions of columbite group minerals, relating well with the Carvalhelhos tin slags. Up to present, the Carvalhelhos slags are amongst the very few ancient tin slags known in Western Europe, and their study can contribute to a better knowledge on ancient tin sources and trade routes

Artificial Intelligence and Human Resources Management: A Bibliometric Analysis

Artificial Intelligence (AI) is increasingly present in organizations. In the specific case of Human Resource Management (HRM), AI has become increasingly relevant in recent years. This article aims to perform a bibliometric analysis of the scientific literature that addresses in a connected way the application and impact of AI in the field of HRM. The scientific databases consulted were Web of Science and Scopus, yielding an initial number of 156 articles, of which 73 were selected for subsequent analysis. The information was processed using the Bibliometrix tool, which provided information on annual production, analysis of journals, authors, documents, keywords, etc. The results obtained show that AI applied to HRM is a developing field of study with constant growth and a positive future vision, although it should also be noted that it has a very specific character as a result of the fact that most of the research is focused on the application of AI in recruitment and selection actions, leaving aside other sub-areas with a great potential for application

Algoritmos de aprendizaje evolutivo y estadístico para la determinación de mapas de malas hierbas utilizando técnicas de teledetección

Este trabajo aborda la resolución de problemas de clasificación binaria utilizando una metodología híbrida que combina la regresión logística y modelos evolutivos de redes neuronales de unidades producto. Para estimar los coeficientes del modelo lo haremos en dos etapas, en la primera aprendemos los exponentes de las funciones unidades producto, entrenando los modelos de redes neuronales mediante computación evolutiva y una vez estimados el número de funciones potenciales y los exponentes de estas funciones, se aplica el método de máxima verosimilitud al espacio de características formado por las covariables iniciales junto con las nuevas funciones de base obtenidas al entrenar los modelos de unidades producto. Esta metodología híbrida en el diseño del modelo y en la estimación de los coeficientes se aplica a un problema real agronómico de predicción de presencia de la mala hierba Ridolfia segetum Moris en campos de cosecha de girasol. Los resultados obtenidos con este modelo mejoran los conseguidos con una regresión logística estándar en cuanto a porcentaje de patrones bien clasificados sobre el conjunto de generalización

Validation by Measurements of a IC Modeling Approach for SiP Applications

The growing importance of signal integrity (SI) analysis in integrated circuits (ICs), revealed by modern systemin-package methods, is demanding for new models for the IC sub-systems which are both accurate, efficient and extractable by simple measurement procedures. This paper presents the contribution for the establishment of an integrated IC modeling approach whose performance is assessed by direct comparison with the signals measured in laboratory of two distinct memory IC devices. Based on the identification of the main blocks of a typical IC device, the modeling approach consists of a network of system-level sub-models, some of which with already demonstrated accuracy, which simulated the IC interfacing behavior. Emphasis is given to the procedures that were developed to validate by means of laboratory measurements (and not by comparison with circuit-level simulations) the model performance, which is a novel and important aspect that should be considered in the design of IC models that are useful for SI analysi

On the formulation of a BEM in the Bézier–Bernstein space for the solution of Helmholtz equation

This paper proposes a novel boundary element approach formulated on the Bézier-Bernstein basis to yield a geometry-independent field approximation. The proposed method is geometrically based on both computer aid design (CAD) and isogeometric analysis (IGA), but field variables are independently approximated from the geometry. This approach allows the appropriate approximation functions for the geometry and variable field to be chosen. We use the Bézier–Bernstein form of a polynomial as an approximation basis to represent both geometry and field variables. The solution of the element interpolation problem in the Bézier–Bernstein space defines generalised Lagrange interpolation functions that are used as element shape functions. The resulting Bernstein–Vandermonde matrix related to the Bézier–Bernstein interpolation problem is inverted using the Newton-Bernstein algorithm. The applicability of the proposed method is demonstrated solving the Helmholtz equation over an unbounded region in a two-and-a-half dimensional (2.5D) domainMinisterio de Economía y Competitividad BIA2016-75042-C2-1-RFondos FEDER POCI-01-0247-FEDER-01775

Fábricas diagenéticas asociadas al paleokarsts del techo de la unidad intermedia del Mioceno de la Cuenca de Madrid.

Los materiales carbonáticos y evaporíticos del techo de la Unidad Intermedia del Mioceno de la Cuenca de Madrid han actuado como soporte de fenómenos de karstificación temprana, cuyo desarrollo ha supuesto un cambio significativo en la evolución del relleno de la cuenca. Dentro de estos materiales se han reconocido carbonatos con fábricas diagenéticas complejas resultado de procesos de diagénesis meteórica superficial. Los procesos predominantes en la evolución diagenética del encajante de la paleokarstificación del techo de la Unidad Intermedia son la dedolomitización y la calcitización/pseudomorfización de yesos. Factores como la composición original del sedimento, la influencia de microorganismos y la hidroquímica de los fluidos diagenéticos han determinado la gran variabilidad de las fábricas diagenéticas reconocidas. [ABSTRACT] Carbonates and evaporites from the top of the Miocene Intermediate Unit of the Madrid Basin have set as host-rock for early karstification phenomena. The development of these karstic processes imply an important change in the depositional evolution of the basin. In these materials, complex diagenetic fabrics formed as a result of shallow meteoric diagenetic processes have been recognized, being dedolomitization and calcitization of gypsums the main diagenetic processes that affected the top of the Miocene Intermediate Unit. The high variability of diagenetic fabrics is thought to be mainly influenced by the original composition of sediments, the activity of microorganisms and the chemistry of diagenetic waters

Influence of the electric energy non-regulated market in the intensive aquaculture plants associated to cooling effluents

En este trabajo se analiza el efecto que la liberalización del mercado eléctrico tiene sobre la variación de los regímenes de temperatura del agua en plantas de acuicultura intensiva que aprovechan los efluentes de refrigeración de centrales generadoras de electricidad. Para ello se han utilizado datos de una instalación dedicada al engorde de anguilas europeas, la cual toma el agua caliente del efluente de refrigeración de la Central Térmica de Puente Nuevo (Córdoba). Los resultados indican que la liberalización del mercado del sector eléctrico tiene una influencia significativa sobre la forma y cantidad de energía generada por la Central Térmica, y por consiguiente sobre el régimen termal del efluente de refrigeración. Los niveles de temperatura en el interior de la instalación son dependientes asimismo de la temperatura del agua en el efluente de refrigeración, estimándose la disminución de los índices de crecimiento debidos a este factor en un 5%.In this paper, the effect of the electric energy non-regulated market in the water thermal regimes variation of intensive fishfarms that use the heated water for cooling of power plants is analysed. This way, data of aneel intensive rearing system was used. In this fishfarm the heated water is drawn from the cooling effluent of the Puente Nuevo power plant (Córdoba). The results show that the non-regulated market has a significant effect on the form and amount of generated energy and the thermal regime of the cooling effluent. The temperature levels in the fishfarm depend of the water temperature of cooling effluent, being estimated the decrease of the growth index in 5%

Extended States in a One-dimensional Generalized Dimer Model

The transmission coefficient for a one dimensional system is given in terms of Chebyshev polynomials using the tight-binding model. This result is applied to a system composed of two impurities located between $N$ sites of a host lattice. It is found that the system has extended states for several values of the energy. Analytical expressions are given for the impurity site energy in terms of the electron's energy. The number of resonant states grows like the number of host sites between the impurities. This property makes the system interesting since it is a simple task to design a configuration with resonant energy very close to the Fermi level $E_F$.Comment: 4 pages, 3 figure