Petrographic markers for archaeometric identification of Montjuic sandstone, the flagship stone of Barcelona (NE Spain)

The present study deals with a particular clastic rock from the Montjuïc hill exploited since Roman times in Barcino (present-day Barcelona (NE Spain)). Polarized and cathodoluminescence microscopies have been used to describe the main petrographic features of Montjuïc sandstones. Several characteristic provenance markers have been identified; among them the most specifically restricted to Montjuïc sandstone are the K-feldspar clasts with authigenic overgrowths. A petrographic survey oriented to the detection of such markers has been fruitfully applied to sculptures, architectural elements, mosaics, and pottery. The petrographic approach has demonstrated that some Roman heritage materials had been erroneously assigned to Montjuïc sandstone and the revision of all the pieces macroscopically assigned to this provenance is advised. The use of Montjuïc sandstone in Roman tesserae has been reported for the first time with interesting implications on previously unreported evidence of Roman extraction at the bottom part of the Montjuïc cliff. Finally, Montjuïc crushed sandstone used as pottery temper has been also reported in the productions of a medieval (12–13th century) workshop in Barcelona. This encourages the study of the distribution of pottery with this particular temper.Financial support from project CGL2013-42167-P (Spanish Ministerio de Economía y Competitividad) is acknowledged.Peer ReviewedPostprint (published version

El Chiringuito de Dios

Publicat a Dialogal: Quaderns de l'Associació UNESCO per al Diàleg Interreligiós. Núm. 39. Tardor 2011

Arqueomagnetisme, contribucions a l'estudi i valorització del patrimoni

La publicació de quatre articles al Journal of Archaeological Science sobre investigacions arqueomagnètiques a Catalunya i Tunísia consolida aquesta línia de recerca al departament de Geologia de la UAB. En aquest article s'explica què és l'arqueomagnetisme i es donen detalls sobre les investigacions dutes a terme en jaciments púnics i romans. Aquest tipus de recerca contribueix a millorar el coneixement històric i a datar jaciments arqueològics, una tasca important per a valoritzar el patrimoni arqueològic.La publicación de cuatro artículos en el Journal of Archaeological Science sobre investigaciones arqueomagnéticas en Cataluña y Túnez consolida esta línea de investigación en el Departamento de Geología de la UAB. En este artículo se explica qué es el arqueomagnetismo y se dan detalles sobre las investigaciones llevadas a cabo en yacimientos púnicos y romanos. Este tipo de investigación contribuye a mejorar el conocimiento histórico y a datar yacimientos arqueológicos, una tarea importante para valorizar el patrimonio arqueológico.The publication of four articles in the Journal of Archaeological Science dealing with archaeomagnetic studies in Catalonia and Tunisia consolidates this research line within the UAB Department of Geology. This popular science article describes what archaeomagnetism is and details are given on the research undertaken at Punic and Roman sites. These types of investigations contribute to improving historical knowledge and dating archaeological sites, an important task in the promotion of archaeological heritage

Video-rate quantitative phase imaging with dynamic acousto-optic defocusing

Various quantitative phase imaging techniques exist capable of characterizing transparent and low-contrast samples without the addition of dyes or fluorescent probes. Among them, the transport of intensity equation (TIE) allows phase retrieval by capturing information from different focal planes without complex inteferometric setups. However, current implementations can be limited in speed or accuracy by the lack of optical systems suitable for fast, reliable, and customizable focal plane selection. Here, we report how combining acousto-optics with pulsed illumination enables accurate and on-demand electronic defocus control suitable for TIE phase imaging at speeds only limited by the camera frame rate. The system exhibits diffraction-limited spatial resolution and high reconstruction fidelity, undistinguishable from traditional mechanical defocusing. We demonstrate its feasibility by measuring different dynamic events at rates as high as 100 phase maps per second. The tunability and ease of implementation of our system can pave the way to democratizing quantitative phase imaging in histopathology, fluid dynamics, and other fields involving thin transparent samples

Enhanced light focusing inside scattering media with shaped ultrasound

Light focusing is the primary enabler of various scientific and industrial processes including laser materials processing and microscopy. However, the scattering of light limits the depth at which current methods can operate inside heterogeneous media such as biological tissue, liquid emulsions, and composite materials. Several approaches have been developed to address this issue, but they typically come at the cost of losing spatial or temporal resolution, or increased invasiveness. Here, we show that ultrasound waves featuring a Bessel-like profile can locally modulate the optical properties of a turbid medium to facilitate light guiding. Supported by wave optics and Monte Carlo simulations, we demonstrate how ultrasound enhances light focusing a factor of 7 compared to conventional methods based on placing optical elements outside the complex medium. Combined with point-by-point scanning, images of samples immersed in turbid media with an optical density up to 15, similar to that of weakly scattering biological tissue, can be reconstructed. The quasi-instantaneous generation of the shaped-ultrasound waves, together with the possibility to use transmission and reflection architectures, can pave the way for the real-time control of light inside living tissue

En arqueomagnetisme ho podem fer millor

El trasllat de dades geomagnètiques al llarg de distàncies de centenars de quilòmetres, suposant que el camp terrestre és dipolar, és una pràctica comuna en arqueomagnetisme. Els errors associats a procedir d'aquesta manera gairebé mai es tenen en compte. Aquest treball analitza la distribució d'aquests errors en l'espai i en el temps i n'extreu conclusions útils per als arqueomagnetistes.El traslado de datos geomagnéticos a lo largo de distancias de centenares de kilómetros suponiendo que el campo terrestre es dipolar es una práctica común en arqueomagnetismo. Los errores asociados a proceder de esta manera casi nunca se tienen en cuenta. Este trabajo analiza la distribución de estos errores en el espacio y el tiempo y extrae conclusiones útiles para los arqueomagnetistas.The relocation of geomagnetic data across distances of hundreds of kilometers and assuming a dipolar geomagnetic field is a common practice in archaeomagnetism. The errors due to this practice are rarely taken into account. This work analyses the time and space distribution of these errors and some useful conclusions for archaeomagnetists have been highlighted

Reconeixement de roques al camp i al laboratori (ICHN-Programa 2016)

Postprint (published version

Rapid quantification of 3D ultrasound fields with wavefront sensing and Schlieren tomography

The rapid and precise characterization of three-dimensional (3D) pressure fields inside water is paramount for ultrasound (US) applications in fields as relevant as biomedicine and acoustic trapping. The most conventional way is to scan point-by-point a needle hydrophone across the field of interest, which is an intrinsically invasive and slow process. With typical acquisition times of hours and even days, this method remains impractical in many realistic scenarios. Alternatively, optical techniques can be used to non-invasively and rapidly measure the changes in light intensity or phase induced by pressure differences. However, these techniques remain largely qualitative: extracting precise pressure values can require extensive calibration, and complex processing, or can be limited to low-pressure ranges. Here, we report how combining wavefront sensing and Schlieren tomography enables rapid and direct quantification of 3D pressure fields while obviating any calibration steps. By simultaneously capturing optical phase and intensity information of the US-perturbed fluid using a Wavefront Sensor and Schlieren projections, respectively, 3D pressure fields over several millimeters cubic can be reconstructed after a few seconds. We present a detailed description of the approach and prove its feasibility by characterizing the US field after an acoustic lens, which is in excellent agreement with calibrated hydrophone measurements and simulations. These results are a significant step forward toward the precise and real-time characterization of ultrasound patterns

Nova eina interactiva per a l'aprenentatge de la cristal·lografia

Malgrat que la cristal·lografia és molt present en el nostre entorn, i els mètodes cristal·logràfics s'utilitzen en molts àmbits, és una ciència complicada per molts científics i tecnòlegs. Un equip multidisciplinar ha desenvolupat una eina informàtica d'ús lliure per tal de facilitar l'aprenentatge i la comprensió de la simetria, un aspecte bàsic de la cristal·lografia, basada en diverses fitxes interactives en 3D. Aquesta eina ja s'ha començat a utilitzar amb èxit en certs graus universitaris.Aunque la cristalografía está muy presente en nuestro entorno, y los métodos cristalográficos se utilizan en muchos ámbitos, es una ciencia complicada para muchos científicos y tecnólogos. Un equipo multidisciplinar ha desarrollado una herramienta informática de uso libre para facilitar el aprendizaje y la comprensión de la simetría, un aspecto básico de la cristalografía, basada en varias fichas interactivas en 3D. Esta herramienta ya se ha empezado a utilizar con éxito en ciertos grados universitarios.Although crystallography is very present in our surroundings, and crystallographic methods are used in many fields, it is a complicated science for many scientists and technologists. A multidisciplinary team has developed a free-to-use tool to facilitate the learning and understanding of symmetry, a basic aspect of crystallography. The tool is based on various 3D interactive files and is already being used successfully in university degrees