Massive Gravity Simplified: A Quadratic Action

We present a simplified formulation of massive gravity where the Higgs fields have quadratic kinetic term. This new formulation allows us to prove in a very explicit way that all massive gravity theories considered so far inevitably have Boulware-Deser ghost in non-trivial fluctuations of background metric.Comment: 8 pages, paragraph added proving that Bianchi identity does not imply vanishing of linearized curvatur

Solid Holography and Massive Gravity

Momentum dissipation is an important ingredient in condensed matter physics that requires a translation breaking sector. In the bottom-up gauge/gravity duality, this implies that the gravity dual is massive. We start here a systematic analysis of holographic massive gravity (HMG) theories, which admit field theory dual interpretations and which, therefore, might store interesting condensed matter applications. We show that there are many phases of HMG that are fully consistent effective field theories and which have been left overlooked in the literature. The most important distinction between the different HMG phases is that they can be clearly separated into solids and fluids. This can be done both at the level of the unbroken spacetime symmetries as well as concerning the elastic properties of the dual materials. We extract the modulus of rigidity of the solid HMG black brane solutions and show how it relates to the graviton mass term. We also consider the implications of the different HMGs on the electric response. We show that the types of response that can be consistently described within this framework is much wider than what is captured by the narrow class of models mostly considered so far.Comment: 43 pages, 4 figure

The Effects of Interpersonal and Noninterpersonal Loss on Music Preference

Through a series of studies, Lee, Andrade, and Palmer (2013) predicted and found that sadness caused by an interpersonal loss creates greater preference for listening to mood-congruent music than sadness caused by a noninterpersonal loss. However, in their experimental procedures, they inadvertently confounded the intensity of the sadness induced in the noninterpersonal and interpersonal sadness conditions, such that the interpersonal sadness condition created stronger feelings of sadness. The current study sought to replicate Lee et al.’s (2013) findings with the modification of unconfounding the intensity of sadness in the interpersonal and noninterpersonal conditions. After controlling for intensity, this study found no significant difference between the interpersonal and noninterpersonal sadness conditions in their preference for mood-congruent music. However, in support of Lee et al. (2013) findings, this study did find that the interpersonal sadness group was more likely to choose sad songs than the neutral group. This result was not found for the noninterpersonal sadness group. In effect, this could indicate an overall preference for mood-congruent music when sadness is caused by an interpersonal loss

Firmes e conservación de vías

Titulación: Grao en Enxeñaría Civil -- Materia: Deseño e Construción de Obras LineaisEsta unidade didáctica serve de peche ao primeiro módulo da programación da materia “Deseño e Construción de Obras Lineais” do segundo curso do Grao en Enxeñaría Civil, que se dedica a sentar as bases da enxeñaría de estradas. No primeiro tema do módulo (UD1) preséntanse os conceptos básicos da enxeñaría do tráfico necesarios para poder abordar o deseño xeométrico, a construción e a conservación dunha estrada. A continuación, no segundo tema (UD2), estúdanse os conceptos fundamentais, as bases teóricas e os condicionantes normativos do deseño xeométrico ou trazado dunha estrada. Analízanse, un por un, os diversos aspectos do proceso de deseño: trazado en planta, trazado en alzado, coordinación entre planta e alzado, e sección transversal. Os seguintes dous temas dedícanse ao estudo da infraestrutura dunha estrada. En primeiro lugar, preséntanse as obras de explanacións (UD3). Neste tema trabállanse, entre outros, os conceptos fundamentais relativos a formación e estabilización de explanadas, que terán unha gran importancia na presente unidade didáctica. En segundo lugar, explícanse os fundamentos do deseño e construción das outras grandes obras de infraestrutura, as obras de drenaxe (UD4). O módulo péchase con esta unidade didáctica, na que se presentan os conceptos fundamentais relacionados cos firmes, que constitúen a superestrutura dunha estrada, e a conservación de vías. Na primeira parte, faise unha descrición dos firmes coas súas principais funcións e características, estúdanse as tipoloxías existentes, e móstranse os factores a considerar no seu deseño. A continuación, para rematar, realízase unha breve introdución á conservación de estradas, facendo fincapé na súa importancia. No segundo módulo da materia estúdase o deseño, construción e conservación doutra tipoloxía de obra lineal, os ferrocarrís. Estas dúas tipoloxías, estradas e ferrocarrís, teñen moitas cousas en común, polo que unha gran cantidade dos contidos traballados no primeiro módulo serán de gran utilidade, senón directamente mediante certas adaptacións, na segunda parte da materia. O alumnado ten a posibilidade de ampliar os coñecementos de firmes e conservación de vías adquiridos nesta unidade didáctica cursando a materia optativa “Firmes e Conservación de Vías” que se imparte no 4º curso da titulación. Ademais de aos alumnos de 2º curso do Grao en Enxeñaría Civil, os contidos presentados nesta unidade didáctica poden serlle de utilidade a outros docentes ou profesionais do sector que desenvolvan a súa actividade no ámbito do deseño, construción ou conservación de estradas.Universidade de Santiago de Compostela. Servizo de Normalización Lingüístic

Mechanistic understanding of mixed-culture fermentations by metabolic modelling

Biorefineries are set to become an important agent in the shift towards a circular economy due to their potential to valorise organic wastes into marketable products. Anaerobic fermentations yielding volatile fatty acids are a key process in this production scheme as their products act as intermediates between the organic wastes and the final biorefinery products. However, their product selectivity is highly influenced by the environmental conditions and the mechanisms governing the process remain unknown. In this thesis, predictive tools were developed with the objective of understanding the mechanisms governing anaerobic fermentations and of designing processes targeting specific volatile fatty acids with high productivity

Energy, Innovation and Transport: The Electrification of Trams in Spain, 1896–1935

[Abstract]: The electrification of trams has been one of the most significant changes in urban transport. It led to price reductions, increased speed, better regularity, comfort and convenience and the popularisation of this means of transport. Its introduction required a new business model, characterised by massive investment, modern management and the use of more sophisticated technology. The Spanish case shows a certain delay in this process along with the importance of the foreign capital (from Belgium and backed by German electro mechanic multinationals), the little intensity of the backward looking effects, because the technological dependency, and the conquest of mobility as the main forward looking effect

Black hole elasticity and gapped transverse phonons in holography

We study the elastic response of planar black hole (BH) solutions in a simple class of holographic models with broken translational invariance. We compute the transverse quasi-normal mode spectrum and the propagation speed of the lowest energy mode. We find that the speed of the lowest mode relates to the BH rigidity modulus as dictated by elasticity theory. This allows to identify these modes as transverse phonons---the pseudo Goldstone bosons of spontaneously broken translational invariance. In addition, we show that these modes have a mass gap controlled by an explicit source of the translational symmetry breaking. These results provide a new confirmation that the BHs in these models do exhibit solid properties that become more manifest at low temperatures. Also, by the AdS/CFT correspondence, this allows to extend the standard results from the effective field theory for solids to quantum-critical materials.Comment: 28 pages, 7 figures; v3: minor revisions, matching JHEP published versio