Elementos auxiliares de construcción en la arquitectura gótica. El pilar «major» de la catedral de Tortosa

Gothic construction wouldn’t have been possible without the use of auxiliary resources which could handle the efforts of the structure during the raising process. In the cathedral of Tortosa case, the ‘libros de obra’ refers to a big pillar used during the building of the apse, which is named ‘pilar major’. The logic of the construction, and also the knowledge about the building phases, has let to deduce the role and the location of this element. Complementarily, it have been verified by graphical methods that the equilibrium of the apse is not possible before the presbitery is closed, without an element of buttressing. The study of the subsoil by means of a georadar has let to identify a solid mass on the center of the apse, where the ‘pilar major’ would be situated. It probably could be the foundation for its construction.La construcción gótica no habría sido posible sin la utilización de medios auxiliares que soportaran los empujes de la estructura durante el proceso de montaje. En el caso de la catedral gótica de Tortosa, los libros de obra hacen referencia a un gran pilar utilizado durante la construcción del ábside, al que se refieren como pilar major. La lógica constructiva, junto con el conocimiento sobre las fases de ejecución, han permitido deducir el funcionamiento y ubicación de este elemento. De manera complementaria, se ha verificado gráficamente que el equilibrio del ábside no es posible antes del cierre del presbiterio sin un elemento de contrarresto. El estudio del subsuelo por medio de un georadar ha permitido identificar una masa sólida situada en el centro del ábside, que coincide con la ubicación del pilar major y que habría servido como base de cimentación para su construcción

Proceso de rotura de una cúpula oval en la catedral de Tortosa. Análisis del mecanismo de colapso

In April of 2011, one of the masonry domes of the cathedral of Tortosa enclosure (Tarragona), built at late XVIII century, suddenly broke. The paper presents the evolution of the rupture and its causes, analyzing the cracking process initiated with the runout of the lantern. It is analyzed the equilibrium conditions starting from the initial constructive assessment in order to know the behavior of the dome and its bearing capacity. There are used complementary traditional graphical methods and tridimensional models by finite elements (FEM) by means of the free software Salome-Meca 6.3. Through the interpretation of the results, the assessment concludes that the dome by itself can hold the weight of the lantern. Thus, the cracking of one of the roof beams causes the bending of the lantern, and therefore the formation of collapse joints from the asymmetrical distribution of loads.En abril del 2011, una de las cúpulas tabicadas del recinto de la catedral de Tortosa (Tarragona), construida a finales del siglo XVIII, rompió repentinamente. El artículo presenta la evolución de la rotura y sus causas, analizando el progresivo proceso de fisuración iniciado con el descentramiento de la linterna. Con el objetivo de conocer el comportamiento de la cúpula y su capacidad portante, se analizan las condiciones de equilibrio a partir del estudio constructivo inicial. Se utilizan de manera complementaria métodos gráficos tradicionales y modelos tridimensionales por elementos finitos (MEF) con el programa libre Salome-Meca 6.3. A partir de la interpretación de los resultados, el estudio concluye que la cúpula por sí sola no tiene capacidad para mantenerse en equilibrio bajo el peso de la linterna. Así el efecto de las termitas sobre la sección de una de las vigas de cubierta provocará el asiento de la linterna y, en consecuencia, la formación de rótulas de colapso a partir de la distribución asimétrica de las cargas

The effects of Δ9-tetrahydrocannabinol on the dopamine system

Δ(9)-tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, is a pressing concern to global mental health. Patterns of use are changing drastically due to legalisation, availability of synthetic analogues (‘spice’), cannavaping and aggrandizements in the purported therapeutic effects of cannabis. Many of THC’s reinforcing effects are mediated by the dopamine system. Due to complex cannabinoid-dopamine interactions there is conflicting evidence from human and animal research fields. Acute THC causes increased dopamine release and neuron activity, whilst long-term use is associated with blunting of the dopamine system. Future research must examine the long-term and developmental dopaminergic effects of the drug

Cortisol, cognition and the ageing prefrontal cortex

The structural and functional decline of the ageing human brain varies by brain region, cognitive function and individual. The underlying biological mechanisms are poorly understood. One potentially important mechanism is exposure to glucocorticoids (GCs; cortisol in humans); GC production is increasingly varied with age in humans, and chronic exposure to high levels is hypothesised to result in cognitive decline via cerebral remodelling. However, studies of GC exposure in humans are scarce and methodological differences confound cross-study comparison. Furthermore, there has been little focus on the effects of GCs on the frontal lobes and key white matter tracts in the ageing brain. This thesis therefore examines relationships among cortisol levels, structural brain measures and cognitive performance in 90 healthy, elderly community-dwelling males from the Lothian Birth Cohort 1936. Salivary cortisol samples characterised diurnal (morning and evening) and reactive profiles (before and after a cognitive test battery). Structural variables comprised Diffusion Tensor Imaging measures of major brain tracts and a novel manual parcellation method for the frontal lobes. The latter was based on a systematic review of current manual methods in the context of putative function and cytoarchitecture. Manual frontal lobe brain parcellation conferred greater spatial and volumetric accuracy when compared to both single- and multi-atlas parcellation at the lobar level. Cognitive ability was assessed via tests of general cognitive ability, and neuropsychological tests thought to show differential sensitivity to the integrity of frontal lobe sub-regions. The majority of, but not all frontal lobe test scores shared considerable overlap with general cognitive ability, and cognitive scores correlated most consistently with the volumes of the anterior cingulate. This is discussed in light of the diverse connective profile of the cingulate and a need to integrate information over more diffuse cognitive networks according to proposed de-differentiation or compensation in ageing. Individuals with higher morning, evening or pre-test cortisol levels showed consistently negative relationships with specific regional volumes and tract integrity. Participants whose cortisol levels increased between the start and end of cognitive testing showed selectively larger regional volumes and lower tract diffusivity (correlation magnitudes <.44). The significant relationships between cortisol levels and cognition indicated that flatter diurnal slopes or higher pre-test levels related to poorer test performance. In contrast, higher levels in the morning generally correlated with better scores (correlation magnitudes <.25). Interpretation of all findings was moderated by sensitivity to type I error, given the large number of comparisons conducted. Though there were limited candidates for mediation analysis, cortisol-function relationships were partially mediated by tract integrity (but not sub-regional frontal volumes) for memory and post-error slowing. This thesis offers a novel perspective on the complex interplay among glucocorticoids, cognition and the structure of the ageing brain. The findings suggest some role for cortisol exposure in determining age-related decline in complex cognition, mediated via brain structure