Palaeoproteomics and microanalysis reveal techniques of production of animal-based metal threads in medieval textiles.

Animal-based metal threads were largely used between the 10th and the fifteenth century, in European, Middle Eastern and Far Eastern textile productions for the decoration of textiles and cloths. They belong to a larger group of metal threads, used either as flat threads or wrapped around a fiber core, that were backed by an organic support (animal or paper). This study focuses on the medieval production of metal threads backed by an animal membrane (e.g. gut membrane), or skin. A total of 91 samples were collected from a corpus of 66 textile fragments belonging to 54 catalogued objects. The relevance and novelty of the present study is represented by the combination of proteomics, cross-section analysis, and scanning electron microscopy (SEM-EDS and SEM-µXRF). The diversity of materials and manufacturing techniques found within each typology of thread, respectively, membrane-based metal threads and skin-based metal threads, hinted at different production technologies. Membrane-based threads were found to be invariably made from cattle gut membrane, coated with gilt-silver leaves. A possible sheep glue adhesive was found in a few samples. Skin-based threads were made from either goat or sheep leather, coated with metal leaves or powder. Within the three different types of coatings identified (silver, gold and gilt-silver), gold coatings were the most represented. Goat leather threads were associated with an egg-white binder, while sturgeon glue was identified as adhesive in all sheep leather threads. Collagen glue from other species (cattle, sheep, horse) was occasionally found in mixed adhesives. In two textiles, the finding of human proteins indicates past contamination due to handling or use. The analytical results show coherence between the fabrication patterns of animal-based metal threads and their probable geographical areas of manufacture, indicating that the study of materials and techniques provide further criteria to classify and group textiles, and trace correlations between manufacturing centers within Eurasian territories.

Estudio Exploratorio sobre Estrategias y Errores de un Estudiante con Trastorno del Espectro Autista al Resolver Problemas de División Partitiva / An Exploratory Study on Strategies and Errors of a Student with Autism Spectrum Disorder when Solving Partitive Division Problems

RESUMEN: En los últimos años ha aumentado notablemente el interés por analizar el rendimiento académico de los estudiantes con trastorno del espectro autista (TEA). Entre las materias escolares, las matemáticas son uno de los grandes obstáculos que encuentran estos estudiantes. Por consiguiente, es fundamental mejorar nuestro conocimiento sobre el modo en que los estudiantes con TEA aprenden diferentes conceptos matemáticos para luego proporcionarles métodos de enseñanza adaptados a sus necesidades. Este documento explora las estrategias y los errores que un estudiante de 11 años diagnosticado con TEA muestra al resolver problemas aritméticos verbales de división. Se diseñó una secuencia de enseñanza compuesta por problemas en dos formatos diferentes: con y sin material manipulativo. Se recogieron datos durante 15 sesiones de una hora en las cuales el estudiante resolvió un total de 49 problemas. Los resultados muestran una clara preferencia por la estrategia de reparto por múltiplos para los problemas en los que dispone de material manipulativo, mientras que recurre principalmente a la estrategia de reparto uno a uno cuando no dispone de material. Se identifica un conjunto de errores relacionados con los significados de las nociones de partición, equidad y representatividad, necesarios para resolver con éxito problemas aritméticos verbales de división partitiva.

ABSTRACT: In recent years there has been an increasing interest in studying the academic performance of students with Autism Spectrum Disorder (ASD). Among school subjects, mathematics is one of the great obstacles that face students with ASD. It is therefore crucial to go in depth into the understanding that they develop on mathematical concepts, to later provide learning instructions adapted to their needs. This paper explores the strategies and errors that an 11-year old student diagnosed with ASD shows when solving partitive division word problems. A teaching sequence has been designed that includes problems in two different formats: with and without support material. The data was collected during 15 one-hour sessions in which the student solved a total of 49 problems. Results show a clear preference for the one-to-many correspondence strategy in the problems with support material whereas the student mainly resorted to the sharing one-by-one strategy when he did not have the material. A list of errors has been identified related to the meaning of the notions of partition, equity and representativeness, required in partitive division word problems.