Restitución analítica, estereocorrelación y Lídar para la generación de modelos digitales de terreno en marismas mareales

Las marismas mareales constituyen uno de los espacios donde la generación de modelos digitales de terreno (MDT) plantean una gran dificultad debido a sus características morfométricas (áreas de escasa variabilidad altimétrica junto a microtopografías de detalle, presencia de vegetación...). Por otra parte, la generación de MDTs constituye un elemento esencial para su caracterización geomorfológica, para los estudios de su vegetación halófila y para la evaluación de riesgos de inundación ligados a una potencial subida del nivel del mar. En esta comunicación se analizan tres MDTs, generados a partir de fuentes de información altimétrica de diferente naturaleza: cotas, curvas y líneas estructurales (x,y,z) a partir de una restitución analítica; una malla de puntos generados por estereocorrelación digital y, finalmente, datos proporcionados por un sensor aerotransportado tipo Lídar. Los procesos de generación del MDT, a su vez, utilizan algoritmos de diferente naturaleza y problemática (en unos casos se centran en métodos de interpolación y, en otros, en los procesos del filtrado y selección). Los resultados obtenidos en un sector de las marismas mareales de Isla Cristina se evalúan en términos de precisión, así como de su adecuación a los objetivos de la caracterización morfométrica de las marismas mareales y del cálculo de riesgos de inundación.The morphometric characteristics of tidal marshes (limited altitudinal range, microtopography and relatively prominent vegetation) make themone of the most difficult areas in which to generate Digital Elevation Models. DEMs have an important role in their geomorphological characterisation, vegetation spatial distribution and risk assessment in relation to flooding and potential sea-level change. In this article digital elevation models are generated from three different sources of altimetric data: x,y,z co-ordinates (contours, point and breaklines) derived from analytical restitution; a mesh of points generated by digital stereo-correlation (10x10 m); and, lastly, data from an airborne LIDAR sensor. The generation process for the digital elevation models uses various algorithms with different characteristics (in some cases based on methods of interpolation and, in others, on methods of filtering and selection). The results achieved in a sector of the Isla Cristina tidal marshes are evaluated in terms of their precision and their adequacy for morphometric characterisation and risk assessment in relation to flooding

Análisis de redes y sensibilidad a la unidad mínima de información poblacional: Sanlúcar de Barrameda (Cádiz)

Actualmente existen fuentes de información que permiten disponer de datos de población desagregada al máximo nivel espacial. Sin embargo, debido al carácter secreto de los datos estadísticos, su grado de detalle debe evitar que éste sea vulnerado, y para ello es necesario emplear unidades mínimas de información poblacional que lo garanticen. Mediante procesos de agregación espacial, es posible encontrar esas unidades mínimas y realizar análisis complejos, respetando la confidencialidad de los datos. El objetivo esencial de este trabajo reside en evaluar la sensibilidad que muestran los resultados obtenidos por distintos tipos de agregación espacial de la población a la asignación de la demanda a centros sanitarios, a partir de métodos derivados del análisis de redes. Para ello se ha empleado como fuentes de datos de población el Registro Longitudinal de la Población de Andalucía en 2011, y el Callejero Digital de Andalucía para la construcción de la red topológica, ambas fuentes referidas al núcleo urbano de Sanlúcar de Barrameda (Cádiz).Geocoding processes of postal addresses and, therefore, their linked data (e.g. population) allows the usage of spatially disaggregated population data at maximum level. However, the level of data-disaggregation should not violate statistical confidentiality. Raster and vector-based analysis can be useful to find intermediate representations of spatial population units that avoid disclosure of statistical confidentiality. The main objective of this paper is to evaluate the sensitivity of network analysis results to the use of different minimum spatial information units, provided by different aggregation methods. Sanlúcar de Barrameda municipality has been chosen as study area. The Registro Longitudinal de la Población de Andalucía (2011) is used as population data source and the Callejero Digital de Andalucía have been selected to build up the topologic network

Ciclos de estabilidad, cambios y variables lentas-rápidas en el paisaje del Área Metropolitana de Concepción a partir de estudios de sistemas socio ecologicos: un análisis exploratorio

Landscapes can maximize their strengths in moments of stability by deeply developing their character and, thus, managing the pressures or disturbances behind slow and fast changes in the Socio-Ecological Systems (SES) to avoid their transformation. Fast variables explain short-term changes and violent rupture processes in stability/change cycles for natural disaster issues. On the other hand, slow variables explain long-term changes and more complex processes in stability/change cycles. The work below focused on studying the Concepción Metropolitan Area (AMC, in Spanish), Chile, which has undergone relevant changes throughout its history but has not been studied as an SES using its slow and fast variables. An exploratory literary review of 150 articles was made in scientific databases without using scientific support software, considering "Concepción" and "Concepción Metropolitan Area" as keywords. The main results highlight short-term phenomena cycles -fast variables- with a major impact, exemplified in natural disasters (earthquakes, tsunamis, floods, fires, and drought), changes in urban planning (urban plans and hygienism), as well as long-term phenomena -slow variables-, with more notable impacts in certain key areas, namely political (conquest and war between indigenous/Spanish/Chilean peoples), economic (boom/bust of business cycles) and environmental (wetland intervention, creation of different protection laws).Los paisajes son capaces de maximizar sus fortalezas en momentos de estabilidad al desarrollar de manera profunda su carácter y, así, manejar las presiones o disturbios que generan cambios en los Sistemas Socio Ecológicos (SSE) en sus variables lentas y rápidas para evitar su transformación. Las variables rápidas son aquellas que explican los cambios de corto plazo y procesos violentos de ruptura en los ciclos de estabilidad/cambio en las temáticas de desastres naturales. Por su parte, las variables lentas corresponden a aquellas que explican los cambios a largo plazo y procesos más complejos en los ciclos de estabilidad/cambio. El trabajo que sigue se abocó al estudio del Área Metropolitana de Concepción (AMC), Chile, la cual ha sufrido cambios relevantes a lo largo de su historia, pero no ha sido estudiada como un SSE en sus variables lentas y rápidas. De forma exploratoria, se realizó una revisión literaria de 150 artículos en las bases de datos científicas sin uso de software científico de apoyo, considerando como palabras claves “Concepción” y “Área Metropolitana de Concepción”. Como resultados principales, se destacan ciclos de fenómenos de corto plazo -variables rápidas- con gran impacto, ejemplificados en desastres naturales (terremotos, maremotos, inundaciones, incendios y sequía), y cambios en los planes de urbanismo (planes urbanos e higienismo), así como fenómenos de largo plazo -variables lentas-, con impactos más memorables en ciertas áreas clave: política (conquista y guerra entre indígenas/españoles/chilenos), economía (auge/caída de ciclos económicos) y medioambiente (intervención humedales, creación de diversas leyes de protección)

On the Use of Bone Remodelling Models to Estimate the Density Distribution of Bones. Uniqueness of the Solution

Bone remodelling models are widely used in a phenomenological manner to estimate numerically the distribution of apparent density in bones from the loads they are daily subjected to. These simulations start from an arbitrary initial distribution, usually homogeneous, and the density changes locally until a bone remodelling equilibrium is achieved. The bone response to mechanical stimulus is traditionally formulated with a mathematical relation that considers the existence of a range of stimulus, called dead or lazy zone, for which no net bone mass change occurs. Implementing a relation like that leads to different solutions depending on the starting density. The non-uniqueness of the solution has been shown in this paper using two different bone remodelling models: one isotropic and another anisotropic. It has also been shown that the problem of non-uniqueness is only mitigated by removing the dead zone, but it is not completely solved unless the bone formation and bone resorption rates are limited to certain maximum values.Ministerio de Economía y Competitividad DPI2013-44371-PMinisterio de Economía y Competitividad DPI2014-58233-

Dinámica hidrogeomorfológica reciente de las barras de meandro en el curso medio del Ebro.

La actividad humana en el entorno del río Ebro y la defensa frente a inundaciones ha causado un gran impacto en los ecosistemas fluviales, afectando intensamente a la dinámica del sistema durante el último siglo. El curso medio del Ebro ha sido muy estudiado, pero no su dinámica reciente, por lo que con el presente estudio se ha constatado la funcionalidad del sistema fluvial mediante la comparación evolutiva de las ortofotografías 1999-2003, 2009, 2015 y 2018, así como la utilización de las herramientas SIG que permiten evaluar y cuantificar los cambios y desplazamientos en determinados puntos de máximo interés geomorfológico como son las barras de meandro e islas donde se mantiene la dinámica de un cauce activo como el Ebro Medio. Los resultados obtenidos reflejan una dinámica escasa en un contexto de ralentización progresiva de la dinámica del cauce, pero en el que aún se registran cambios en estos puntos dinámicos, denotando un curso fluvial funcional que es capaz de movilizar sedimentos. Es de vital importancia la conservación y protección de esta dinámica hidrogeomorfológica evitando dañar el funcionamiento del ecosistema fluvial mediante acciones humanas directas. <br /

Influence of musculotendon geometry variability in muscle forces and hip bone-on-bone forces during walking

Inverse dynamics problems are usually solved in the analysis of human gait to obtain reaction forces and moments at the joints. However, these actions are not the actual forces and moments supported by the joint structure, because they do not consider the forces of the muscles acting across the joint. Therefore, to analyse bone-on bone forces it is necessary to estimate those muscle forces. Usually, this problem is addressed by means of optimization algorithms. One of the parameters required to solve this problem is the musculotendon geometry. These data are usually taken from cadavers or MRI data from several subjects, different from the analysed subject. Then, the model is scaled to the subject morphology. This procedure constitutes a source of error. The goals of this work were two. First, to perform a sensitivity analysis of the influence of muscle insertion locations on the muscle forces acting on the hip joint and on the hip joint bone-on-bone forces. Second, to compare the hip joint bone-on-bone forces during gait cycle obtained through muscle insertion locations taken from a musculoskeletal model template and a scaling procedure to those obtained from a subject-specific model using an MRI of the subject. The problem was solved using OpenSim. Results showed that anatomical variability should be analysed from two perspectives. One the one hand, throughout the gait cycle, in a global way. On the other hand, at a characteristic instant of the gait cycle. Variations of ±1 cm in the position of the attachment points of certain muscles caused variations of up to 14.21% in averaged deviation of the muscle forces and 58.96% in the peak force in the modified muscle and variations up to 57.23% in the averaged deviation of the muscle force and up to 117.23% in the peak force in the rest of muscles. Then, the influence of that variability on muscle activity patterns and hip bone-on-bone forces could be described more precisely. A biomechanical analysis of a subject-specific musculoskeletal model was carried out. Using MRI data, variations up to 5 cm in the location of the insertion points were introduced. These modifications showed significant differences between the baseline model and the customized model: within the range [-12%, 10%] for muscle forces and around 35% of body weight for hip bone-on-bone forces.Ministerio de Economía, Industria y Competitividad DPI2016-80796-P

Gestión e integración de datos altimétricos y batimétricos en la costa andaluza: uso del “model builder”

En esta comunicación se presenta la estrategia adoptada en la incorporación de la información altimétrica y batimétrica de la costa andaluza al Subsistema del Litoral y Medio Marino (SSLyMM), realizado para la Consejería de Medio Ambiente. En primer lugar se opto por modificar el objetivo final: no se trata de generar un único MDE continuo, sino de mantener los datos altimétricos y batimétricos permanentemente actualizados en un base de datos espacial y diseñar una herramienta interactiva que produzca los MDEs a demanda en función de las aplicaciones en las que se usará. Para ello, se diseño una herramienta utilizando la aplicación ModelBuilder de ArcGis 9.3 que encadena varios procesos de análisis espacial a partir de la información original almacenada en la base de datos (curvas, cotas, sondas o datos raster). Estos procesos se concretan en algoritmos que primero interpolan la batimetría y posteriormente ajustan el datum del MDE resultante al datum altimétrico (mareógrafo Alicante). En segundo lugar se interpola la altimetría y se ajusta a la línea de costa del SSLyMM y, en tercer lugar, se extrae el 0 hidrográfico ya ajustado al 0 de Alicante y se interpola la zona intermareal con los datos existentes desde dicho cero hasta la línea de costa. La posibilidad de configurar variables y parámetros que se deciden interactivamente por el usuario antes de ejecutar la herramienta permite definir el área de análisis y la resolución espacial del modelo resultante, el algoritmo de interpolación a utilizar y la paleta de color a aplicar al MDE resultante entre otras opciones. Por otra parte, esta estrategia permite incorporar de forma inmediata la nueva información disponible (muy variable en el medio submarino) y ajustar las características del MDE (resolución espacial, interpolador, etc.) resultante a las demandas de la aplicación temática para la que va a utilizar (modelado de oleaje, navegación marítima, evaluación de riesgos, generación sombreados para fondos cartográficos, etc.).This paper presents the methodology used for the integration of the altimetric and bathymetric data of the andalusiam coast into the Littoral and Marine Environment Subsystem (SSLyMM), made for the Environmental Regional Ministry. The aim of this work was not the generation of a only continuous digital elevation model (DEM), as it was firstly required, but also the design of a strategy for keeping the altimetric and bathymetric data always updated in a geodatabase and the development of an interactive tool to produce different DEMs depending on the requirements of the potential user. The tool was designed using the application ModelBuilder in ArcGis 9.3 that uses different spatial analysis processes applied to the original data stored in the spatial database. Those processes reflects a set of algorithms that firstly interpolated the bathymetry data and then adjust the resulting DEM to the national altimetric datum, located in the Mean Sea Level at the Alicante tide gauge in Spain (NMMA). The second step was the interpolation of the altimetry data and the adjustment of the shoreline contained in the SSLyMM. The third step was the extraction of the corrected hydrographic zero contour (once referred to the NMMA) and the interpolation of the intertidal area elevation by means of the available data of this area. The area of the DEM, its spatial resolution, the algorithm that would be used for spatial interpolation and other variables and parameters can be chosen by the user before executing the tool. This strategy let the incorporation of potential new information available (what is quite usual on bathymetry due to the scarcity of data), and the adjustment of the DEM characteristic (spatial resolution, interpolation methods...) to the requirements of the use and applications that the DEM might have

Influence of the Temporomandibular Joint in the Estimation of Bone Density in the Mandible through a Bone Remodelling Model

Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedThe temporomandibular joint (TMJ) plays a key role in the distribution of stresses in the mandible during mastication and consequently in the distribution of bone density, due to the interconnection between both variables through bone remodelling. Two finite element models of the mandible were compared to study the influence of the redistribution of stresses produced by the joint: (1) a model without TMJ, but with simplified boundary conditions to replace the joint, as done in previous models; (2) a more realistic model including the articular disc and some ligaments present in the TMJ. The stresses and strains in both models were compared through the strain energy density, used in many bone remodelling models as a measure of the mechanical stimulus. An anisotropic bone remodelling model was used to simulate the behaviour of mandible bone and to estimate its density distribution. The results showed that the TMJ strongly affects the stress distribution, the mechanical stimulus, and eventually the bone density, and not only locally in the condyle, but also in the whole mandible. It is concluded that it is utterly important to include a detailed model of the TMJ to estimate more correctly the stresses in the mandible during mastication and, from them, the bone density and anisotropy distribution

The Correlation between Bone Density and Mechanical Variables in Bone Remodelling Models: Insights from a Case Study Corresponding to the Femur of a Healthy Adult

Bone remodelling models (BRM) are often used to estimate the density distribution in bones from the loads they are subjected to. BRM define a relationship between a certain variable measuring the mechanical stimulus at each bone site and either the local density or the local variation of density. This agrees with the Mechanostat Theory, which establishes that overloaded bones increase their density, while disused bones tend to decrease their density. Many variables have been proposed as mechanical stimuli, with stress or strain energy density (SED) being some of the most common. Yet, no compelling reason has been given to justify the choice of any of these variables. This work proposes a set of variables derived from the local stress and strain tensors as candidates for mechanical stimuli; then, this work correlates them to the density in the femur of one individual. The stress and strain tensors were obtained from a FE model and the density was obtained from a CT-scan, both belonging to the same individual. The variables that best correlate with density are the stresses. Strains are quite uniform across the femur and very poorly correlated with density, as is the SED, which is, therefore, not a good variable to measure the mechanical stimulus

Sexting among adolescents: The emotional impact and influence of the need for popularity

Sexting refers to the exchange of sexual content material via technological devices. The definitions of this phenomenon vary greatly, mainly, depending on the types of sexting: primary and secondary. Besides the above, there is no common perspective on whether sexting is a risk behavior that entails some type of impact by itself or not and, in such a case, whether this impact varies according to gender. In addition, the need to be popular has shown to be a factor that could increase the probability of being involved in sexting. The present study analyzes the potential emotional impact of sexting as well as the effect of the need for popularity on this phenomenon and if it varies according to gender. The sample comprised 2,356 high school students (46.8% female, 53.2% male; age range 11–18 years old, M = 13.72; SD = 1.31) belonging to 12 compulsory secondary education (ESO) schools from the south of Spain. To assess sexting implication, four questions were presented to participants (sending, receiving, forwarding, and receiving sexts via intermediary). Scales, self-report, about emotional impact (depressed, annoyed, and active) and need for popularity were also applied. The results obtained show that, although sexting has a clear emotional impact on adolescents, it does not appear to generate a negative impact among those involved, at least in the short term. Concretely, this phenomenon seems to trigger emotions related to activation in boys and girls (I feel lively, energetic, satisfied, ready, determined, active). Additionally, with respect to the need for popularity, its relevance, specially, in relation to active emotional impact has been confirmed by the analyses. Statistical models found for boys and girls were similar. In addition, some differences in emotional impact by gender were found, girls feeling more depressed and annoyed in secondary sexting, and boys more active regarding both types of sexting.National Research Plan of the Government of Spain PSI2017-86723-RNational Research Plan of the Government of Spain EDU201344627-PMinistry of Science, Innovation and Universities of the Government of Spain for the Training of University Teachers FPU15/0503