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

Belgian investment in trams and light railways. An international approach, 1892-1935

[Abstract]: In this article the international investments made by Belgium are analysed both geographically and quantitatively, within the urban transport sector, a sector which has been little researched and in which Belgium played a leading role in several countries. The article looks at the importance of foreign ownership in transport enterprises, a subject of on-going debate in transport historiography. The hypothesis that the article puts forward is that the promotion of tramway enterprises abroad, via Belgian capital, is linked with the search for new markets for the steel and engineering industries. To this end new evidence will be provided which sheds light on this relationship. This contribution will help us to better understand the role of Belgian capital in promoting tramway networks throughout the world, the motives behind such investment and the mechanisms and strategies used

La última iniciativa francesa en los ferrocarriles españoles: la Compañía de los Ferrocarriles Estratégicos y Secundarios de Alicante, 1910-1920

[Resumen]: La inversión extranjera jugó un papel relevante en la economía española, en especial durante el período 1850-1914. El sector en el que, sin duda, este rol resultó más signifi cativo fue el ferroviario. El grueso de la inversión, y también la más precoz, procedió de Francia. El artículo analiza la plasmación de dicha inversión en una empresa concreta, la Compañía de los Ferrocarriles Estratégicos y Secundarios de Alicante. Se trata de un caso singular en cuanto a que representa uno de los pocos ejemplos de participación francesa en la vía estrecha y el último en iniciarse. La estructura del trabajo es la siguiente: en primer lugar examinaremos brevemente la evolución económica y la red ferroviaria alicantinas para poder contextualizar la inserción de esta empresa. A continuación, analizaremos en detalle las características y comportamiento de la misma a lo largo de la década de gestión francesa.[Abstract]: The foreign investment played a relevant role in the Spanish economy, especially during the period 1850- 1914. The railways were, undoubtedly, the sector in which this intervention resulted most signifi cant. The majority of the investment, and also the earliest one, came from France. The article analyzes a case study: the Compañía de los Ferrocarriles Estratégicos y Secundarios de Alicante. It is a quite singular case because it was one of the few French companies in the narrow gauge railways and the last one to be set up. The structure of the article is as follows: fi rst we will examine briefl y Alicante´s economic evolution and railway network in order to better understand this company. Next, we will analyze in detail its characteristics and performance during the decade of French management

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