673 research outputs found
The Meis homeoprotein regulates the axolotl Prod 1 promoter during limb regeneration
During limb regeneration in salamanders the blastemal cells give rise only to structures distal to the level of amputation. This proximodistal identity can be regulated by ectopic expression of Meis homeoproteins or the three finger protein Prod 1 which acts at the cell surface. It has been suggested that Meis acts by regulating the transcription of Prod 1. We have sequenced the axolotl Prod 1 promoter and selected two candidate sites for binding Meis homeoproteins. The sites were mutated in various combinations in promoters expressing a luciferase reporter gene. The promoter activity was assayed by nucleofecting AL1 cells, a cultured axolotl limb cell line that expresses both Prod 1 and Meis 1 and 2. The activity of the promoter was inhibited by 60% after mutation at Meis site 1, but not at Meis site 2. The promoter constructs were electroporated into axolotl limb blastemas and the wild type promoter was more active in a proximal blastema than in a contralateral distal blastema. The wild type promoter was significantly more active than a (site 1+site 2) mutant promoter in contralateral proximal blastemas, but the promoters were equivalent in contralateral distal blastemas. The separate site 1 or site 2 mutants were not significantly different from wild type in contralateral proximal blastemas, thus contrasting with the site 1 results in AL1 cells. These data provide strong support for the hypotheses that the Prod 1 promoter is regulated on the proximodistal axis, and that Meis homeoproteins directly regulate the promoter on this axis during limb regeneration in addition to cultured cells
Alumnos con deficiencia psíquica: aspectos a tener en cuenta en las clases de educación física
Los alumnos con deficiencia psíquica tienen los mismos estadios de desarrollo que el resto de niños, pero tienen un retraso en su desarrollo. A esto se añaden una serie de características afectivas, sociales, etc., que hay que tener en cuenta para planificar la clase. El artículo propone una seria de aspectos metodológicos que nos van a permitir dar las clases en óptimas condiciones
Modelo de cuantificación del consumo energético en edificación
The research conducted in this paper focuses on the generation of a model for the quantification of energy consumption in building. This is to be done through one of the most relevant environmental impact indicators associated with weight per m2 of construction, as well as the energy consumption resulting from the manufacturing process of materials used in building construction.
The practical application of the proposed model on different buildings typologies in Seville, will provide information regarding the building materials, the subsystems and the most relevant construction elements. Hence, we will be able to observe the impact the built surface has on the environment.
The results obtained aim to reference the scientific community, providing quantitative data comparable to other types of buildings and geographical areas. Furthermore, it may also allow the analysis and the characterization of feasible solutions to reduce the environmental impact generated by the different materials, subsystems and construction elements commonly used in the different building types defined in this study.La investigación realizada en el presente trabajo plantea la generación de un modelo de cuantificación del consumo energético en edificación, a través de uno de los indicadores de impacto ambiental más relevantes asociados al peso por m2 de construcción, el consumo energético derivado del proceso de fabricación de los materiales de construcción empleados en edificación.
La aplicación práctica del modelo propuesto sobre diferentes tipologías edificatorias en Sevilla aportará información respecto a los materiales de construcción, subsistemas y elementos constructivos más impactantes, permitiendo visualizar la influencia que presenta la superficie construida en cuanto al impacto ambiental generado.
Los resultados obtenidos pretenden servir de referencia a la comunidad científica, aportando datos numéricos que podrán ser comparados en otras tipologías y ámbitos geográficos, a la vez que permitirán analizar y precisar mejoras en cuanto al impacto ambiental generado por los diferentes materiales, subsistemas y elementos constructivos habitualmente utilizados en las tipologías edificatorias definidas
Plant wax biomarkers in human evolutionary studies
Abstract Plant wax biomarkers are an innovative proxy for reconstructing vegetation composition and structure, rainfall intensity, temperature, and other climatic and environmental dynamics. Traditionally used in earth sciences and climate studies from ?off-site? ocean and lake records, biomarker research is now incorporated in archeology and paleoanthropology to answer questions relating to past human-environment interactions and human evolution. Biomarker research is generating new and exciting information on the ecological context in which Homo and its closest relatives evolved, adapted, and invented stone tool technologies. In this review, we examine plant wax biomarkers and their use in reconstructing past plant landscapes and hydroclimates. We summarize the applications of plant wax molecular proxies in archeological research, assess challenges relating to taphonomy, consider the role of modern plant ecosystems in interpreting ancient habitats, and examine case studies conducted at key paleoanthropological locations in eastern and southern Africa and Europe.1 Introduction 2 Complementary addition to multi-proxy studies 3 Taphonomic normalization 4 Establishing the plant wax ecology of modern african soil 5 Plant waxes shed light on multiple aspects of human evolution 5.1 Orbital forcing and hominin ecology 5.2 Plant landscape variability 5.3 Hominin targeted ecotones 5.4 Activity areas in caves and rock shelters 6 Where do we go from here
Dynamical Critical Phenomena and Large Scale Structure of the Universe: the Power Spectrum for Density Fluctuations
As is well known, structure formation in the Universe at times after
decoupling can be described by hydrodynamic equations. These are shown here to
be equivalent to a generalization of the stochastic Kardar--Parisi--Zhang
equation with time-- dependent viscosity in epochs of dissipation. As a
consequence of the Dynamical Critical Scaling induced by noise and
fluctuations, these equations describe the fractal behavior (with a scale
dependent fractal dimension) observed at the smaller scales for the
galaxy--to--galaxy correlation function and the Harrison--Zel'dovich
spectrum at decoupling. By a Renormalization Group calculation of the
two--point correlation function between galaxies in the presence of (i) the
expansion of the Universe and (ii) non--equilibrium, we can account, from first
principles, for the main features of the observed shape of the power spectrum.Comment: 13 pages with 2 encapsulated PostScript figures included, gzipped tar
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Large scale emergent properties of an autocatalytic reaction-diffusion model subject to noise
The non-equilibrium dynamic fluctuations of a stochastic version of the
Gray-Scott (GS) model are studied analytically in leading order in perturbation
theory by means of the dynamic renormalization group. There is an attracting
stable fixed point at one-loop order, and the asymptotic scaling of the
correlation functions is predicted for both spatial and temporally correlated
noise sources. New effective three-body reaction terms, not present in the
original GS model, are induced by the combined interplay of the fluctuations
and nonlinearities.Comment: 13 pages, 2 figure
Active wetting of epithelial tissues
Development, regeneration and cancer involve drastic transitions in tissue
morphology. In analogy with the behavior of inert fluids, some of these
transitions have been interpreted as wetting transitions. The validity and
scope of this analogy are unclear, however, because the active cellular forces
that drive tissue wetting have been neither measured nor theoretically
accounted for. Here we show that the transition between 2D epithelial
monolayers and 3D spheroidal aggregates can be understood as an active wetting
transition whose physics differs fundamentally from that of passive wetting
phenomena. By combining an active polar fluid model with measurements of
physical forces as a function of tissue size, contractility, cell-cell and
cell-substrate adhesion, and substrate stiffness, we show that the wetting
transition results from the competition between traction forces and contractile
intercellular stresses. This competition defines a new intrinsic lengthscale
that gives rise to a critical size for the wetting transition in tissues, a
striking feature that has no counterpart in classical wetting. Finally, we show
that active shape fluctuations are dynamically amplified during tissue
dewetting. Overall, we conclude that tissue spreading constitutes a prominent
example of active wetting --- a novel physical scenario that may explain
morphological transitions during tissue morphogenesis and tumor progression
Multivariable PID Control of a Boiler
[EN] This document presents the proposal of the authors to the Control Engineering Benchmark 2016, organized by the Control Engineering Group of the Spanish Committee of Automatica. This is the winner design in the postgraduate category. The benchmark proposes the design of a control system for a boiler, that is modelled by a nonlinear multivariable model with three input, three output, and a measurable disturbance. The control system presented in this report is based on the design of a multivariable proportional-integral-derivative (PID) controller by using convex optimization techniques. In addition, prefilters for the references and for the measurable disturbance have also been proposed. Finally, the performance of the designed control system is shown under the same scenarios to the ones considered in the benchmark.[ES] Este documento presenta la propuesta de los autores para el Concurso en Ingeniería de Control 2016 (CIC2016) organizado por el Grupo Temático de Ingeniería de Control del Comité Español de Automática (CEA). Esta propuesta resultó ganadora en la categoría de estudiantes de máster y postgrado. El concurso consiste en el diseño de un sistema de control para una caldera de vapor, que es modelada por un modelo no lineal multivariable con tres entradas, tres salidas y una perturbación medible. El sistema de control propuesto en este documento se basa en el diseño de un controlador tipo proporcional integrador derivativo (PID) multivariable, mediante técnicas de optimización convexa. Además, se contempla el uso de más grados de libertad mediante el diseño de precompensadores para referencias y para la perturbación medible. Finalmente, se analiza el desempeño del sistema de control diseñado, bajo los escenarios propuestos en el concurso.Este trabajo está financiado por el Ministerio de Economía e Innovación de España (incluyendo cofinanciación FEDER-UE) bajo los proyectos DPI2013-47100-C2-1-P y DPI2016-79278-C2-1-R.Mercader, P.; Cánovas, CD.; Baños, A. (2018). Control PID multivariable de una caldera de vapor. Revista Iberoamericana de Automática e Informática. 16(1):15-25. https://doi.org/10.4995/riai.2018.9034SWORD152516
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