Experiment: Influence of CO2 and nitrogen limitation on the coccolith volume of Emiliania huxleyi (Haptophyta)

Coccolithophores, a key phytoplankton group, are one of the most studied organisms regarding their physiological response to ocean acidification/carbonation. The biogenic production of calcareous coccoliths has made coccolithophores a promising group for paleoceanographic research aiming to reconstruct past environmental conditions. Recently, geochemical and morphological analyses of fossil coccoliths have gained increased interest in regard to changes in seawater carbonate chemistry. The cosmopolitan coccolithophore Emiliania huxleyi (Lohm.) Hay and Mohler was cultured over a range of pCO2 levels in controlled laboratory experiments under nutrient replete and nitrogen limited conditions. Measurements of photosynthesis and calcification revealed, as previously published, an increase in particulate organic carbon production and a moderate decrease in calcification from ambient to elevated pCO2. The enhancement in particulate organic carbon production was accompanied by an increase in cell diameter. Changes in coccolith volume were best correlated with the coccosphere/cell diameter and no significant correlation was found between the coccolith volume and the particulate inorganic carbon production. The conducted experiments revealed that the coccolith volume of E. huxleyi is variable with aquatic CO2 concentration but its sensitivity is rather small in comparison with its sensitivity to nitrogen limitation. Comparing coccolith morphological and geometrical parameters like volume, mass and size to physiological parameters under controlled laboratory conditions is an important step to understand variations in fossil coccolith geometry.

The CoastColour Round Robin datasets: a database to evaluate the performance of algorithms for the retrieval of water quality parameters in coastal waters

The CoastColour project Round Robin (CCRR) project (http://www.coastcolour.org) funded by the European Space Agency (ESA) was designed to bring together a variety of reference datasets and to use these to test algorithms and assess their accuracy for retrieving water quality parameters. This information was then developed to help end-users of remote sensing products to select the most accurate algorithms for their coastal region. To facilitate this, an inter-comparison of the performance of algorithms for the retrieval of in-water properties over coastal waters was carried out. The comparison used three types of datasets on which ocean colour algorithms were tested. The description and comparison of the three datasets are the focus of this paper, and include the Medium Resolution Imaging Spectrometer (MERIS) Level 2 match-ups, in situ reflectance measurements and data generated by a radiative transfer model (HydroLight). The datasets mainly consisted of 6,484 marine reflectance associated with various geometrical (sensor viewing and solar angles) and sky conditions and water constituents: Total Suspended Matter (TSM) and Chlorophyll-a (CHL) concentrations, and the absorption of Coloured Dissolved Organic Matter (CDOM). Inherent optical properties were also provided in the simulated datasets (5,000 simulations) and from 3,054 match-up locations. The distributions of reflectance at selected MERIS bands and band ratios, CHL and TSM as a function of reflectance, from the three datasets are compared. Match-up and in situ sites where deviations occur are identified. The distribution of the three reflectance datasets are also compared to the simulated and in situ reflectances used previously by the International Ocean Colour Coordinating Group (IOCCG, 2006) for algorithm testing, showing a clear extension of the CCRR data which covers more turbid waters.

Using ground-penetrating radar, topography and classification of vegetation to model the sediment and active layer thickness in a periglacial lake catchment, Western Greenland, link to shapefiles

The geometries of a catchment constitute the basis for distributed physically based numerical modeling of different geoscientific disciplines. In this paper results from ground-penetrating radar (GPR) measurements, in terms of a 3D model of total sediment thickness and active layer thickness in a periglacial catchment in western Greenland, is presented. Using the topography, thickness and distribution of sediments is calculated. Vegetation classification and GPR measurements are used to scale active layer thickness from local measurements to catchment scale models. Annual maximum active layer thickness varies from 0.3 m in wetlands to 2.0 m in barren areas and areas of exposed bedrock. Maximum sediment thickness is estimated to be 12.3 m in the major valleys of the catchment. A method to correlate surface vegetation with active layer thickness is also presented. By using relatively simple methods, such as probing and vegetation classification, it is possible to upscale local point measurements to catchment scale models, in areas where the upper subsurface is relatively homogenous. The resulting spatial model of active layer thickness can be used in combination with the sediment model as a geometrical input to further studies of subsurface mass-transport and hydrological flow paths in the periglacial catchment through numerical modelling.

La Casa Domínguez. Alejandro de la Sota: Construir - Habitar

La Tesis Doctoral nace con una intensa vocación pedagógica. La hipótesis de trabajo se establece en torno a una cuestión de interés personal, un tema sobre el que se vertebran, desde el comienzo del doctorado, los diferentes cursos y trabajos de investigación: LA CASA DOMÍNGUEZ como paradigma de la dialéctica en la obra de Alejandro de la Sota. La clasificación de la realidad en categorías antagónicas determina un orden conceptual polarizado, una red de filiaciones excluyentes sobre las que Sota construye su personal protocolo operativo: la arquitectura intelectual o popular, experimental o tradicional, universal o local, ligera o pesada, elevada o enterrada, etc. Se propone el abordaje de una cuestión latente en el conjunto de la obra ‘sotiana’, desde la disección y el análisis de una de sus obras más pequeñas: la casa Domínguez. Se trata de una organización sin precedentes, que eleva la estrategia dialéctica al paroxismo: la vivienda se separa en dos estratos independientes, la zona de día, elevada, y la zona de noche, enterrada; cada uno de los estratos establece su propio orden geométrico y constructivo, su propio lenguaje y carácter, su propia identidad e incluso su propio presupuesto. Las relaciones entre interior y exterior se especializan en función de la actividad o el reposo, estableciéndose una compleja red de relaciones, algunas evidentes y otras celosamente veladas, entre los diferentes niveles. La estancia destinada a las tareas activas se proyecta como un objeto de armazón ligero y piel fría; la precisa geometría del cubo delimita la estancia vigilante sobre el paisaje conquistado. La ladera habitada se destina al reposo y se configura como una topografía verde bajo la que se desarrollan los dormitorios en torno a patios, grietas y lucernarios, generando un paisaje propio: la construcción del objeto frente a la construcción del lugar La casa Domínguez constituye uno de los proyectos menos estudiados, y por lo tanto menos celebrados, de la obra de Don Alejandro. Las publicaciones sucesivas reproducen la documentación gráfica junto a la memoria (epopeya) que el propio Sota compone para la publicación del proyecto. Apenas un par de breves textos críticos de Miguel Ángel Baldellou y, recientemente de Moisés Puente, abordan la vivienda como tema monográfico. Sin embargo, la producción de proyecto y obra ocupó a De la Sota un periodo no inferior a diez años, con casi cien planos dibujados para dos versiones de proyecto, la primera de ellas, inédita. El empeño por determinar hasta el último detalle de la ‘pequeña’ obra, conduce a Sota a controlar incluso el mobiliario interior, como hiciera en otras obras ‘importantes’ como el Gobierno Civil de Tarragona, el colegio mayor César Carlos o el edificio de Correos y Telecomunicaciones de León. La complicidad del cliente, mantenida durante casi cuarenta años, habilita el despliegue de una importante colección de recursos y herramientas de proyecto. La elección de la casa Domínguez como tema central de la tesis persigue por lo tanto un triple objetivo: en primer lugar, el abordaje del proyecto como paradigma de la dialéctica ‘sotiana’, analizando la coherencia entre el discurso de carácter heroico y la obra finalmente construida; en segundo lugar, la investigación rigurosa, de corte científico, desde la disección y progresivo desmontaje del objeto arquitectónico; y por último, la reflexión sobre los temas y dispositivos de proyecto que codifican la identificación entre la acción de construir y el hecho de habitar, registrando los aciertos y valorando con actitud crítica aquellos elementos poco coherentes con el orden interno de la propuesta. This doctoral thesis is the fruit of a profound pedagogical vocation. The central hypothesis was inspired by a question of great personal interest, and this interest has, since the very beginning of the doctorate, been the driving force behind all subsequent lines of research and investigation. The “Casa Domínguez” represents a paradigm of the dialectics found in the work of Alejandro de la Sota. The perception of reality as antagonistic categories determines a polarized conceptual order, a network of mutually excluding associations upon which Sota builds his own personal operative protocol: intellectual or popular architecture, experimental or traditional, universal or local, heavy or light, above or below ground, etc. Through the analysis and dissection of the “Casa Domínguez”, one of Sota’s smallest projects, an attempt is made to approach the underlying question posed in “Sotian” work as a whole. This is about organization without precedent, raising the strategic dialectics to levels of paroxysm. The house is divided into two separate levels, the day-time level above ground, and the lower night-time level beneath the surface of the ground. Each level has its own geometrical and stuctural order, its own language and character, its own identity and even has its own construction budget. The interaction between the two areas is centered on the two functions of rest and activity, and this in turn establishes a complex relationship network between both, which is sometimes self-evident, but at other times jealously guarded. The living area designed for daily activity is presented as an object of light structure and delicate skin; the precise geometry of the cube delimiting the ever watchful living area’s domain over the land it has conquered. A green topography is created on the slope below which lies an area adapted for rest and relaxation. Two bedrooms, built around patios, skylights and light crevices, generate an entirely independent environment: the construction of an object as opposed to the creation of a landscape. The “Casa Domínguez” project has been subject to much less scrutiny and examination than Don Alejandro’s other works, and is consequently less well-known. A succession of journals have printed the blueprint document together with a poetic description (epopee), composed by Sota himself, to mark the project’s publication. There has, however, scarcely been more than two brief critical appraisals, those by Miguel Ángel Baldellou and more recently by Moisés Puente, that have regarded the project as a monographic work. The project and works nevertheless occupied no less than ten years of De La Sota’s life, with over a hundred draft drawings for two separate versions of the project, the first of which remains unpublished. The sheer determination to design this “small” work in the most meticulous detail, drove Sota to manage and select its interior furniture, as indeed he had previously done with more “important” works like the Tarragona Civil Government, César Carlos College, or the Post Office telecommunications building in León. Client collaboration, maintained over a period of almost forty years, has facilitated an impressive array of the project’s tools and resources. The choice of “Casa Domínguez” as the central subject matter of this thesis, was made in pursuance of a triple objective: firstly, to approach the project as a paradigm of the “Sotian” dialectic, the analysis of the discourse between the heroic character and the finished building; secondly, a rigorous scientific investigation, and progressive disassembling and dissecting of the architectonic object; and finally, a reflection on aspects of the project and its technology which codify the identification between the action of construction and the reality of living, thus marking its achievements, whilst at the same time subjecting incoherent elements of the proposal’s established order to a critical evaluation.

Showing the Past: Integrating Cartographic Collections through Virtual Map Rooms

Spatial Data Infrastructures have become a methodological and technological benchmark enabling distributed access to historical-cartographic archives. However, it is essential to offer enhanced virtual tools that imitate the current processes and methodologies that are carried out by librarians, historians and academics in the existing map libraries around the world. These virtual processes must be supported by a generic framework for managing, querying, and accessing distributed georeferenced resources and other content types such as scientific data or information. The authors have designed and developed support tools to provide enriched browsing, measurement and geometrical analysis capabilities, and dynamical querying methods, based on SDI foundations. The DIGMAP engine and the IBERCARTO collection enable access to georeferenced historical-cartographical archives. Based on lessons learned from the CartoVIRTUAL and DynCoopNet projects, a generic service architecture scheme is proposed. This way, it is possible to achieve the integration of virtual map rooms and SDI technologies bringing support to researchers within the historical and social domains.

Geometric Integrability of the Camassa-Holm Equation. II

It is known that the Camassa–Holm (CH) equation describes pseudo-spherical surfaces and that therefore its integrability properties can be studied by geometrical means. In particular, the CH equation admits nonlocal symmetries of “pseudo-potential type”: the standard quadratic pseudo-potential associated with the geodesics of the pseudo-spherical surfaces determined by (generic) solutions to CH, allows us to construct a covering π of the equation manifold of CH on which nonlocal symmetries can be explicitly calculated. In this article, we present the Lie algebra of (first-order) nonlocal π-symmetries for the CH equation, and we show that this algebra contains a semidirect sum of the loop algebra over sl(2,R) and the centerless Virasoro algebra. As applications, we compute explicit solutions, we construct a Darboux transformation for the CH equation, and we recover its recursion operator. We also extend our results to the associated Camassa–Holm equation introduced by J. Schiff.

Modelos de elementos finitos con aplicación tridimensional de la analogía fluido-fibra, para predecir el comportamiento mecánico de piezas estructurales de madera bajo la presencia de los principales tipos de nudos

Los nudos son los defectos que más disminuyen la resistencia de piezas de madera en la escala estructural, al ocasionar no solo una discontinuidad material, sino también la desviación de las fibras que se encuentran a su alrededor. En la década de los 80 se introdujo la teoría de la analogía fluido-fibra, como un método que aproximaba adecuadamente todas estas desviaciones. Sin embargo en su aplicación tridimensional, nunca se consideraron las diferencias geométricas en el sentido perpendicular al eje longitudinal de las piezas estructurales, lo cual imposibilitaba la simulación numérica de algunos de los principales tipos de nudos, y disminuía la precisión obtenida en aquellos nudos en los que la modelización sí era viable. En este trabajo se propone un modelo programado en lenguaje paramétrico de un software de elementos finitos que, bajo una formulación en tres dimensiones más general, permitirá estudiar de forma automatizada el comportamiento estructural de la madera bajo la influencia de los principales tipos de nudos, a partir de la geometría visible de los mismos y la posición de la médula en la pieza, y el cual ha sido contrastado experimentalmente, simulando de forma muy precisa el comportamiento mecánico de vigas sometidas a ensayos de flexión a cuatro puntos. Knots are the defects that most reduce the strength of lumber at the structural level, by causing not only a material discontinuity but also the deviation of the fibers that surround them. In the 80's it was introduced the theory of the flow-grain analogy as a method to approximating adequately these deviations. However, in three-dimensional applications, geometrical differences in the direction perpendicular to the longitudinal axis of the structural specimens were never considered before, which prevented the numerical simulation of some of the main types of knots, and decreased the achieved precision in those kind of knots where modeling itself was possible. This paper purposes a parametric model programmed in a finite element software, in the way that with a more general three-dimensional formulation, an automated study of the structural behavior of timber under the influence of the main types of knots is allowed by only knowing the visible geometry of such defects, and the position of the pith. Furthermore that has been confirmed experimentally obtaining very accurately simulations of the mechanical behavior of beams under four points bending test.

Isotopic prediction calculation methodologies: application to Vandellos-II Reactor cycles 7-11

Determining as accurate as possible spent nuclear fuel isotopic content is gaining importance due to its safety and economic implications. Since nowadays higher burn ups are achievable through increasing initial enrichments, more efficient burn up strategies within the reactor cores and the extension of the irradiation periods, establishing and improving computation methodologies is mandatory in order to carry out reliable criticality and isotopic prediction calculations. Several codes (WIMSD5, SERPENT 1.1.7, SCALE 6.0, MONTEBURNS 2.0 and MCNP-ACAB) and methodologies are tested here and compared to consolidated benchmarks (OECD/NEA pin cell moderated with light water) with the purpose of validating them and reviewing the state of the isotopic prediction capabilities. These preliminary comparisons will suggest what can be generally expected of these codes when applied to real problems. In the present paper, SCALE 6.0 and MONTEBURNS 2.0 are used to model the same reported geometries, material compositions and burn up history of the Spanish Van de llós II reactor cycles 7-11 and to reproduce measured isotopies after irradiation and decay times. We analyze comparisons between measurements and each code results for several grades of geometrical modelization detail, using different libraries and cross-section treatment methodologies. The power and flux normalization method implemented in MONTEBURNS 2.0 is discussed and a new normalization strategy is developed to deal with the selected and similar problems, further options are included to reproduce temperature distributions of the materials within the fuel assemblies and it is introduced a new code to automate series of simulations and manage material information between them. In order to have a realistic confidence level in the prediction of spent fuel isotopic content, we have estimated uncertainties using our MCNP-ACAB system. This depletion code, which combines the neutron transport code MCNP and the inventory code ACAB, propagates the uncertainties in the nuclide inventory assessing the potential impact of uncertainties in the basic nuclear data: cross-section, decay data and fission yields

Concrete Swelling in Two Spanish Dams

Several chemical reactions are able to produce swelling of concrete for decades after its initial curing, a problem that affects a considerable number of concrete dams around the world. Principia has had several contracts to study this problem in recent years, which have required reviewing the state-ofthe-art, adopting appropriate mathematical descriptions, programming them into user routines in Abaqus, determining model parameters on the basis of some parts of the dams’ monitored histories, ensuring reliability using some other parts, and finally predicting the future evolution of the dams and their safety margins. The paper describes some of the above experience, including the programming of sophisticated nonisotropic swelling models, that must be compatible with cracking and other nonlinearities involved in concrete behaviour. The applications concentrate on two specific cases, an arch-gravity dam and a double-curvature arch dam, both with a long history of concrete swelling and which, interestingly, entailed different degrees of success in the modelling efforts

Architectural design and construction costs, tools towards territorial sustainability

This paper is presented in CIB: Management and Innovation Sustainable Built Environment 2011, as the study and analysis of the residential model of a rural area from the Iberian Peninsula, specifically applied to the case of the province of Cáceres, in the autonomous region of Extremadura, in Spain. To this end, from a database made up of building projects whose real costs are known, it is intended to establish the links of the different parameters studied through the corresponding functions of statistical analysis. One of the main objectives of this process is constituted by the possibility of establishing those design variables of higher economic importance, so as to keep an economic control of these parameters, generally geometrical and typological, from the very start of the project. And, in general, a higher optimization of resources in the construction of dwellings in the rural environment from their design is intended.

The Ciborium or Lantern Tower of Valencia Cathedral: Geometry, Construction and Stability

Early 18th century treatise writer Tomas Vicente Tosca1 includes in his Tratado de la montea y cortes de Canteria [On Masonry Design and Stone Cutting], what is an important documentary source about the lantern of Valencia Cathedral. Tosca writes about this lantern as an example of vaulting over cross arches without the need of buttresses. A geometrical description is followed by an explanation of the structural behavior which manifests his deep understanding of the mechanics of masonry structures. He tries to demonstrate the absence of buttresses supporting his thesis on the appropriate distribution of loads which will reduce the "empujos" [horizontal thrusts] to the point of not requiring more than the thickness of the walls to stand (Tosca [1727] 1992, 227-230). The present article2 assesses T osca' s appreciation studying how loads and the thrusts they generate are transmitted through the different masonry elements that constitute this ciborium. In order to do so, we first present a geometrical analysis and make considerations regarding its materials and construction methods to, subsequently, analyze its stability adopting an equilibrium approach within the theoretical framework of the lower bound limit analysis.

The Ciborium or Lantern Tower of Valencia Cathedral: Geometry, Construction and Stability

Early 18th century treatise writer Tomas Vicente Tosca1 includes in his Tratado de la montea y cortes de Canteria [On Masonry Design and Stone Cutting], what is an important documentary source about the lantern of Valencia Cathedral. Tosca writes about this lantern as an example of vaulting over cross arches without the need of buttresses. A geometrical description is followed by an explanation of the structural behavior which manifests his deep understanding of the mechanics of masonry structures. He tries to demonstrate the absence of buttresses supporting his thesis on the appropriate distribution of loads which will reduce the "empujos" [horizontal thrusts] to the point of not requiring more than the thickness of the walls to stand (Tosca [1727] 1992, 227-230). The present article2 assesses T osca' s appreciation studying how loads and the thrusts they generate are transmitted through the different masonry elements that constitute this ciborium. In order to do so, we first present a geometrical analysis and make considerations regarding its materials and construction methods to, subsequently, analyze its stability adopting an equilibrium approach within the theoretical framework of the lower bound limit analysis.

Comparison of experimental and numerical sloshing loads in partially filled tanks

Sloshing describes the movement of liquids inside partially filled tanks, generating dynamic loads on the tank structure. The resulting impact pressures are of great importance in assessing structural strength, and their correct evaluation still represents a challenge for the designer due to the high level of nonlinearities involved, with complex free surface deformations, violent impact phenomena and influence of air trapping. In the present paper, a set of two-dimensional cases, for which experimental results are available, is considered to assess the merits and shortcomings of different numerical methods for sloshing evaluation, namely two commercial RANS solvers (FLOW-3D and LS-DYNA), and two academic software (Smoothed Particle Hydrodynamics and RANS). Impact pressures at various critical locations and global moment induced by water motion in a partially filled rectangular tank, subject to a simple harmonic rolling motion, are evaluated and predictions are compared with experimental measurements. 2012 Copyright Taylor and Francis Group, LLC.

Selective area growth of a- and c-plane GaN nanocolumns by molecular beam epitaxy using colloidal nanolithography

Selective area growth of a-plane GaN nanocolumns by molecular beam epitaxy was performed for the first time on a-plane GaN templates. Ti masks with 150 nm diameter nanoholes were fabricated by colloidal lithography, an easy, fast and cheap process capable to handle large areas. Even though colloidal lithography does not provide a perfect geometrical arrangement like e-beam lithography, it produces a very homogeneous mask in terms of nanohole diameter and density, and is used here for the first time for the selective area growth of GaN. Selective area growth of a-plane GaN nanocolumns is compared, in terms of anisotropic lateral and vertical growth rates, with GaN nanocolumns grown selectively on the c-plane

Concrete Swelling in Existing Dams

Several chemical reactions are able to produce swelling of concrete for decades after its initial curing, a problem that affects a considerable number of concrete dams around the world. Principia has had several contracts to study this problem in recent years, which have required reviewing the state-of-the-art, adopting appropriate mathematical descriptions, programming them into user routines in Abaqus, determining model parameters on the basis of some parts of the dams’ monitored histories, ensuring reliability using some other parts, and finally predicting the future evolution of the dams and their safety margins. The paper describes some of the above experience, including the programming of sophisticated non-isotropic swelling models, that must be compatible with cracking and other nonlinearities involved in concrete behaviour. The applications concentrate on two specific cases, an archgravity dam and a double-curvature arch dam, both with a long history of concrete swelling and which, interestingly, entailed different degrees of success in the modelling efforts