Aether Unleashed

We follow a low-energy effective theory approach to identify the general class of theories that describes a vector field (of unconstrained norm) coupled to gravity. The resulting set may be regarded as a generalization of the conventional vector-tensor theories, and as a high-momentum completion of aether models. We study the conditions that a viable cosmology, Newtonian limit and absence of classical and quantum instabilities impose on the parameters of our class of models, and compare these constraints with those derived in previously studied and related cases. The most stringent conditions arise from the quantum stability of the theory, which allows dynamical cosmological solutions only for a non-Maxwellian kinetic term. The gravitational constant in the Newtonian limit turns to be scale dependent, suggesting connections to dark matter and degravitation. This class of theories has a very rich gravitational phenomenology, and offers an ample but simple testing ground to study modifications of gravity and their cosmological implications.Comment: 41 pages, 1 figure and 4 tables. v2: Minor changes and added references, matches version accepted for publicatio

Derrick's theorem beyond a potential

Scalar field theories with derivative interactions are known to possess solitonic excitations, but such solitons are generally unsatisfactory because the effective theory fails precisely where nonlinearities responsible for the solitons are important. A new class of theories possessing (internal) galilean invariance can in principle bypass this difficulty. Here, we show that these galileon theories do not possess stable solitonic solutions. As a by-product, we show that no stable solitons exist for a different class of derivatively coupled theories, describing for instance the infrared dynamics of superfluids, fluids, solids and some k-essence models.Comment: 4 page

Accelerating Universes from Short-Range Interactions

We show that short-range interactions between the fundamental particles in the universe can drive a period of accelerated expansion. This description fits the early universe. In the present day universe, if one postulates short-range interactions or a sort of "shielded gravity", the picture may repeat.Comment: 4 pages, 1 figure. Discussion expanded. Some references added. Matches version in print. To appear in Phys. Lett.

Dualities of Latin America

Determining whether the current situation of Latin America is better described as "post-neoliberalism" or as "commodities consensus" requires an analysis of recent changes in the region. Capitalism has expanded in agriculture and mining, accentuating the preeminence of basic exports. Traditional industry is declining, and remittances and tourism have increased in importance. Local capitalists associated with foreign corporations have replaced the national bourgeoisie, while the exodus of peasants consolidates labor precariousness, poverty, and inequality. At the same time, the United States is deploying troops to reorganize its domination. The South American rebellions have limited neoliberal aggression and achieved unusual victories in other parts of the world. The concept of post-neoliberalism emphasizes the region's political turn toward autonomy but overlooks the persistence of the economic model generated during the previous phase. The opposing concept, commodities consensus, highlights the extractivism prevailing throughout the region but plays down the extreme divergences among right-wing, center-left, and radical governments in all other areas. Both concepts contain part of the truth, but neither fully explains the regional scenario.Para determinar si la situación actual de Latinoamérica es mejor descrita como “postneoliberalismo” o como un “consenso de los commodities” hay que hacer un análisis de los cambios recientes en la región. El capitalismo se ha expandido en la agricultura y la minería, acrecentando la preeminencia de las exportaciones básicas. La industria tradicional ha disminuido, y la importancia del turismo y las remesas ha aumentado. Los capitalistas locales asociados con empresas extranjeras han reemplazado a la burguesía nacional, mientras que el éxodo de los campesinos ha consolidado la precariedad laboral, la pobreza y la desigualdad. Al mismo tiempo, Estados Unidos despliega tropas para reorganizar su dominio. Las rebeliones en América del Sur han puesto barreras a la agresión neoliberal y logrado victorias inusuales en otras partes del mundo. El concepto del postneoliberalismo destaca el giro político de la región hacia la autonomía pero con una tendencia a la persistencia del modelo económico generado durante la fase anterior. El otro concepto, el consenso de las commodities, destaca el extractivismo que prevalece en toda la región pero minoriza las divergencias entre los gobiernos de derecha, centro-izquierda y radicales en todas las demás áreas. Ambos conceptos son parcialmente ciertos, pero no explican totalmente el escenario regional.Fil: Katz, Claudio Isaac. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Effective Theory Approach to the Spontaneous Breakdown of Lorentz Invariance

We generalize the coset construction of Callan, Coleman, Wess and Zumino to theories in which the Lorentz group is spontaneously broken down to one of its subgroups. This allows us to write down the most general low-energy effective Lagrangian in which Lorentz invariance is non-linearly realized, and to explore the consequences of broken Lorentz symmetry without having to make any assumptions about the mechanism that triggers the breaking. We carry out the construction both in flat space, in which the Lorentz group is a global spacetime symmetry, and in a generally covariant theory, in which the Lorentz group can be treated as a local internal symmetry. As an illustration of this formalism, we construct the most general effective field theory in which the rotation group remains unbroken, and show that the latter is just the Einstein-aether theory.Comment: 45 pages, no figures

VERTEX: A Compendium of Research and Design

From the foreword: Vertex was organized to showcase some of the UNLV School of Architecture’s most prominent areas of strength. Our multidisciplinary design foundation program is the initial building block that instills in students an ethos of systematic inquiry through making. Appropriately structured processes of experimentation and production using a variety of tools and media help students develop significant spatial understandings through the sequential act of drawing and making. The spatial understandings developed in the design foundation, supplemented by a culture of inquiry through making that is cultivated in our design studios, prepare our students to creatively engage in a rigorous study of relevant disciplinary subjects that range from the design of arid environments to hospitality, and from building technologies (including design-build) to healthcare interior design. Note: The written sections of the book are featured in Digital Scholarship@UNLV. The complete volume may be purchased at the Buy this book link abovehttps://digitalscholarship.unlv.edu/vertex/1000/thumbnail.jp

Commissioning of a synchrotron-based proton beam therapy system for use with a Monte Carlo treatment planning system

This work tackles the commissioning and validation of a novel combination of a synchrotron-based proton beam therapy system (Hitachi, Ltd.) for use with a Monte Carlo treatment planning system (TPS). Four crucial aspects in this configuration have been investigated: (1) Monte Carlo-based correction performed by the TPS to the measured integrated depth-dose curves (IDD), (2) circular spot modelling with a single Gaussian function to characterize the synchrotron physical spot, which is elliptical, (3) the modelling of the range shifter that enables using only one set of measurements in open beams, and (4) the Monte Carlo dose calculation model in small fields. Integrated depth-dose curves were measured with a PTW Bragg peak chamber and corrected, with a Monte Carlo model, to account for energy absorbed outside the detector. The elliptical spot was measured by IBA Lynx scintillator, EBT3 films and PTW microDiamond. The accuracy of the TPS (RayStation, RaySearch Laboratories) at spot modelling with a circular Gaussian function was assessed. The beam model was validated using spread-out Bragg peak (SOBP) fields. We took single-point doses at several depths through the central axis using a PTW Farmer chamber, for fields between 2 × 2cm and 30 × 30cm. We checked the range-shifter modelling from open-beam data. We tested clinical cases with film and an ioni- zation chamber array (IBA Matrix). Sigma differences for spots fitted using 2D images and 1D profiles to elliptical and circular Gaussian models were below 0.22 mm. Differences between SOBP measurements at single points and TPS calculations for all fields between 5 × 5 and 30 × 30cm were below 2.3%. Smaller fields had larger differences: up to 3.8% in the 2 × 2cm field. Mean differences at several depths along the central axis were generally below 1%. Differences in range- shifter doses were below 2.4%. Gamma test (3%, 3 mm) results for clinical cases were generally above 95% for Matrix and film. Approaches for modelling synchrotron proton beams have been validated. Dose values for open and range- shifter fields demonstrate accurate Monte Carlo correction for IDDs. Elliptical spots can be successfully modelled using a circular Gaussian, which is accurate for patient calculations and can be used for small fields. A double-Gaussian spot can improve small-field calculations. The range-shifter modelling approach, which reduces clinical commissioning time, is adequat

La puesta en valor de los servicios ecosistémicos que ofrecen los arroyos de llanura como una medida de mitigación de las inundaciones: el caso del A° del Gato en el partido de La Plata

El concepto de servicios ecosistémicos surge en la década de los 70 como una forma de dar a conocer a la sociedad y a los tomadores de decisiones el vínculo directo que existe entre el bienestar humano y el mantenimiento de las funciones básicas del planeta. Más específicamente los servicios ecosistémicos hidrológicos se relacionan con la conservación de las cuencas hidrográficas entre los que se reconocen la regulación de flujos hidrológicos, reducción del impacto de las inundaciones, de la erosión del suelo, de la sedimentación en los cursos de agua, incluyendo también el mantenimiento o mejoramiento de la calidad del agua, de la recarga de acuíferos y de los hábitats acuáticos, entre otros. Desde el punto de vista del abastecimiento humano se pueden reconocer las principales fuentes de agua para beber, cocinar, asearse y cultivar en zonas donde las precipitaciones son insuficientes, además de generar energía eléctrica para manufacturar diversos productos, como así también ser fuente de alimentos. Asimismo, desde el punto de vista hidrológico, cumplen un rol en el ciclo global del agua ya que junto con los acuíferos subterráneos acumulan la precipitación que es conducida por escurrimientos hacia el mar, desde donde continúa el ciclo hidrológico. Cabe resaltar que los humedales y las planicies de inundación de los ríos absorben el agua de lluvia, reducen el escurrimientos disminuyendo así de los daños por inundaciones y ayudan a la recarga de aguas subterráneas contribuyendo también a mitigar las sequías. Asimismo considerando los aspectos culturales cumplen un importante rol en actividades de recreación, además de proporcionar beneficios estéticos, educativos y espirituales. Atendiendo la conservación de la biodiversidad desempeñan un papel destacado como proveedores de hábitats para diversas especies de flora y fauna, constituyendo reservorios ricos en diversidad genética (Brauman et al., 2007, Brauman, 2015, Thorp et al., 2013).Hydrological ecosystem services involve the regulation of water flows, the reduction of the flooding impact, the soil erosion and the sediment accumulation in the watercourses, also including the maintenance and improvement of the water quality, the aquiferous recharge and the aquatic habitats. The impermeability of the soil due to urbanization, the acceleration of drainings, the building of obstacles to the water flow in streams and rivers together with pollution are recognized as the main causes contributing to magnify the consequences of storms in urban and suburban areas. With the aim of showing the consequences of this type of interferences and the lossesin services and goods of the Pampean plain water flows, the case of the Gato stream is here explained. Its basin is inhabited by over 400,000 people, with approximately 50% of urbanized area and a deficient drainage system. The occupation of the alluvial valley and the lack of an integral plan for flooding risks are acknowleged as the main causes for the recurrent floods in this basin. The extreme expression of these events was observed on 2nd and 3rd April, 2013, as a consequence of a meteorological phenomenon which reached over 301 mm of water in four hours with an average intensity of 100.3 mm/h, causing the death of 89 people and over 2200 evacuated people together with an immense material loss. A study carried out in three areas of the basin, in order to identify the main causes that reduce the ecological quality of the stream, revealed that in sectors of the mid and low basin there is a deficient water quality with habitat destruction and the consequent loss of biodiversity. On the other hand, a detailed analysis of a fluvial overflow swamp, located on the upper basin, demonstrated the capacity of these areas of the basin which contribute to the improvement of water quality functioning as green filters and generating a proper environment to host diverse flora and fauna. They also retain water during storms and favor the regulation of the increase of the downstream flow contributing to alleviate the effects of floods. The review of the draining management techniques of the basin is essential. It is, therefore, necessary to count with the integral knowledge of the structure and functioning of the different areas of the basin. It is also very important to make the population aware of the necessity of their contribution, in order to regain the ecosystem services which have been partially or completely lost

La puesta en valor de los servicios ecosistémicos que ofrecen los arroyos de llanura como una medida de mitigación de las inundaciones : El caso del Arroyo del Gato en el partido de La Plata

Fil: Gómez, Nora. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Rodrigues Capítulo, Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Colautti, Darío César. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Mariñelarena, Alejandro J.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Licursi, Magdalena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Cochero, Joaquín. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Armendariz, Laura Cecila. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Maroñas, Miriam Edith. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Donadelli, Jorge L.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Jensen, Roberto F.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: García de Souza, Javier Ricardo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Maiztegui, Tomás. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: García, Ignacio. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Sathicq, María Belén. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Suarez, Jimena Camila. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Cortese, Bianca. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; Argentin

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km² resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-km² pixels (summarized from 8500 unique temperature sensors) across all the world’s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.publishedVersio