An optical fibre sensor has been implemented towards pyridine vapors detection; to achieve this, a novel vapochromic material has been used, which, in solid state, suffers a change in colour from blue to pink-white in presence of pyridine vapours. This complex is added to a solution of PVC (Poly Vinyl Chloride), TBP (Tributylphosphate) and tetrahydrofuran (THF), forming a plasticized matrix; by dip coating technique, the sensing material is fixed onto a cleaved ended optical fibre. The fabrication process was optimized in terms of number of dips and dipping speed, evaluating the final devices by dynamic range. Employing a reflection set up, the absorbance spectra and changes in the reflected optical power of the sensors were registered to determine their response. A linear relation between optical power versus vapor concentration was obtained, with a detection limit of 1 ppm (v/v).

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Characterizing raw material of stone tools used by Late Neolithic and Copper Age communities is important for interpreting access to available sources and establishing regional routes of distribution. Ichnological analysis may be used to help characterize lithic material and determine the source of artifacts. Here we report for the first time the existence of trace fossils in artifacts from the Late Neolithic and Copper Age of southern Spain. Ichnological analysis indicates a trace fossil assemblage consisting of relatively scarce small‐sized Chondrites and abundant Phycosiphon. A regional survey of natural outcrops and chert quarries indicates the presence of discrete trace fossils only in the samples from geological formations that are part of the Campo de Gibraltar Complex. Ichnological composition in these samples is similar to that discerned in the artifacts and suggests that this was the probable source of the chert used in tool manufacture. © 2010 Wiley Periodicals, Inc.

Resumen. Las representaciones esquemáticas del abrigo de Laja Alta (Jimena de la Frontera, España) son el testimonio más claro de la existencia en la antigüedad de embarcaciones a vela en el Mediterráneo occidental. Mayoritariamente se han venido adscribiendo al I o finales del II milenio a.C. Este artículo ofrece nuevos calcos y datos para una mejor comprensión del conjunto de motivos del abrigo. Entre los resultados obtenidos planteamos cuestionar la anterior cronología. Las dataciones absolutas confirman su frecuentación entre el IV-III milenio a.C., durante el Neolítico Reciente y Calcolítico del sur de Iberia. Una época de importantes transformaciones en la región. Además, el resto de resultados obtenidos son leídos en términos de datación relativa (tipos de motivos, su contexto cultural, análisis de pigmentos mediante reflectancia óptica y superposición de figuras), no apartándose de las dataciones obtenidas. La distribución espacial de las figuras indica que los barcos ocupan el centro de la cavidad, son el tema principal de Laja Alta, el resto está determinado por la escena naval. Esta conclusión tiene implicaciones históricas para la transferencia de tecnologías, bienes e ideas que dieron forma a las sociedades del Neolítico Reciente y la Edad del Cobre de Europa occidental y norte de África.Abstract. The Laja Alta rock shelter paintings (Jimena de la Frontera, Spain) are the clearest existing testimony of sailing vessels from ancient times in the western Mediterranean. The majority opinion of the research has dated the naval scene in the first or the end of the second mill. BC. This article offers new reproductions and data for a better understanding of the figures represented. Based on the results obtained, we propose a different hypothesis. The absolute dates confirm that the rock shelter was used in the IV-III mill. cal. BC., the Late Neolithic and Copper Age. It was a time of important community transformations. Besides, others datas (types of figures, cultural context, pigment analysis by optical reflectance and superposition of figures) do not deviate from the results dates. The topographical distribution indicates that the boats occupy a central position in the rock shelter. Thus, the boats are the main theme of the paintings of Laja Alta and the rest of the motifs are determined by the naval scene. This conclusion has important historical implications for the transfer of technologies, goods and ideas that shaped the societies of the Late Neolithic and Copper Age of the Western Europe and North Africa.