Contribución al conocimiento litoestratigráfico del Cretácico de la zona central de la región asturiana

Se describen, de muro a techo en la zona media de la serie cretácica asturiana, tres unidades litoestratigráficas: de margas nodulosas grises, calcáreo-detrítica y detrítica micácea. Estas unidades resultan litológicamente características y fácilmente reconocibles en el campo. En consecuencia, se proponen como buenos niveles guía en una extensión que abarca desde el W de Oviedo hasta el meridiano de Ceceda

Datos estructurales sobre el anticlinal de "San Emiliano-Valgrande" y unidades periféricas (Cordillera Cantábrica)

Se mencionan algunos datos estructurales sobre el anticlinal mecanizado que se extiende, desde las proximidades de San Emiliano (León) hasta el nacimiento del río Valgrande (Asturias), el cual, resulta ser una muy destacada estructura de replegamiento de la Unidad Cabalgante de Pajares. Se citan algunas otras observaciones sobre el carácter, en estazona, de la Unidad Cabalgante de Villamanín, que se le superpone, adquiriendo aquí una notable complejidad en la zona frontal, definiendo una serie de escamas y, conjuntamente, una semiventana tectónica de cierta importancia

Reconocimiento de señales de deformación en pudingas de la Cuenca Carbonífera Central de Asturias

Se describe la existencia de señales de deformación (impresiones cóncavas, torsiones y fracturas) de nexo tectónico en cantos de pudingas cuarcíticas del Carbonífero (Westfaliense C-D, probablemente) de la Cuenca Central de Asturias (España)

Warm Electromagnetic Forming of AZ31B Magnesium Alloy Sheet

Historically, electromagnetic forming technology has mainly been used to form parts from aluminium and copper alloys due to their excellent electrical conductivity and limited formability by conventional methods. However, little research has been carried out in high strain rate forming of magnesium alloy sheets. Therefore, in the current contribution electromagnetic forming experiments are performed for rolled AZ31B magnesium alloy sheet at different temperatures up to 250°C. Two forming operations are studied in this paper, i.e. drawing and bending operations. The final deformations achieved for the different conditions were measured and the effect of both temperature and discharged energy on deformation is shown. Bending experiments at room temperature were recorded by means of a high speed camera and the springback behaviour at high strain rates is evaluated. In one hand, increasing the forming temperature the yield strength of the material decreases while on the other hand, the electrical conductivity and thus the induced forces are also decreased. It is observed that increasing the forming temperature, for a given discharged energy, the maximum height of the deformed part is decreased. However, increasing the discharged energy at warm temperatures, higher deformation values are achieved without failure. Additionally, bending experiments show that springback effect is also decreased at warm conditions. It is concluded that warm electromagnetic forming is a suitable procedure to manufacture magnesium parts

Measuring School Engagement: Validation and Measurement Equivalence of the Student Engagement Scale on Angolan Male and Female Adolescents

School engagement is defined primarily in relation to the participation of the student in academic achievement, and it is viewed as a multidimensional and integrative construct, or macroconstruct made up of several dimensions. The most repeated typology recognizes three specific dimensions: Cognitive, behavioral, and emotional (affective). Recently, a fourth new dimension, personal agency, has been proposed, which reflects students’ constructive engagement with the academic instructions. F. Veiga has been the first to present a self-report instrument, in Portuguese, to measure these four components, the Student Engagement Scale-4 dimensions (SES-4DS). This research has studied the validity and reliability of this scale and its gender invariance in a sample of 2034 Angolan students. Results have shown a clear scalar invariant factor structure, some reliability problems, and adequate convergent and nomological validity. Latent differences were found between males and females for cognitive and affective engagement. Results are discussed in light of the existing literature

Quantitative analysis of electronic transport through weakly-coupled metal/organic interfaces

Using single-crystal transistors, we have performed a systematic experimental study of electronic transport through oxidized copper/rubrene interfaces as a function of temperature and bias. We find that the measurements can be reproduced quantitatively in terms of the thermionic emission theory for Schottky diodes, if the effect of the bias-induced barrier lowering is included. Our analysis emphasizes the role of the coupling between metal and molecules, which in our devices is weak due to the presence of an oxide layer at the surface of the copper electrodes.Comment: 4 pages, 3 figure

Temporal and spatial variability of prehistoric aquatic resource procurement: a case study from Mesolithic Northern Iberia

Prehistoric shell middens hold valuable evidence of past human–environment interactions. In this study, we used carbon (δ13C) and oxygen (δ18O) stable isotopes of Mytilus galloprovincialis shells excavated from El Perro, La Fragua and La Chora, three Mesolithic middens in Cantabria, Northern Spain, to examine hunter-gatherer subsistence strategies in terms of seasonality and collection areas. Furthermore, we used shell δ18O to reconstruct water temperature during the early Holocene. Stable isotopes reveal a shellfish harvesting diversification trend represented by the gradual establishment of the upper estuaries as new procurement areas and an increase of harvesting mobility in both coastal and in-land sites. These innovations in subsistence strategies during the Mesolithic coincided with major changes in the surrounding environment as attested by the water temperature reconstructions based on δ18O and backed by several global and regional records. Overall, our results show that shell δ13C and δ18O stable isotopes have an underexplored potential as provenance proxies which stimulates their application to the archaeological record to further understand prehistoric human resource procurement and diet