A new approach for initial callus growth during fracture healing in long bones

The incidence of bone fracture has become a major clinical problem on a worldwide scale. In the past two decades there has been an increase in the use of computational tools to analyse the bone fracture problem. In several works, various study cases have been analysed to compare human and animal bone fracture healing. Unfortunately, there are not many publications about computational advances in this field and the existing approaches to the problem are usually similar. In this context, the objective of this work is the application of a diffusion problem in the model of the bone fragments resulting from fracture, working together with a mesh-growing algorithm that allows free growth of the callus depending on the established conditions, without a pre-meshed domain. The diffusion problem concerns the different biological magnitudes controlling the callus growth, among which Mesenchymal Stem Cells and chondrocytes concentrations were chosen, together with Tumour Necrosis Factor α and Bone Morphogenetic Protein as the factors influencing the velocity in the callus formation. A Finite Element approach was used to solve the corresponding diffusion problems, obtaining the concentration values along the entire domain and allowing detecting the zones in which biological magnitudes reach the necessary thresholds for callus growth. The callus growth is guided by a geometrical algorithm which performs an additional mesh generation process (self-added mesh) at each step of the iterative procedure until complete callus formation. The proposed approach was applied to different types of diaphyseal femoral fractures treated by means of intramedullary nailing. Axisymmetric models based on triangular quadratic elements were used, obtaining results in good agreement with clinical evidence of these kinds of fractures. The algorithm proposed has the advantage of a natural callus growth, without the existence of a previous mesh that may affect the conditions and direction of growth. The approach is intended for the initial phase of callus growth. Future work will address the implementation of the corresponding formulations for tissue transformation and bone remodelling in order to achieve complete fracture healing

Gradient Methods for Solving Stackelberg Games

Stackelberg Games are gaining importance in the last years due to the raise of Adversarial Machine Learning (AML). Within this context, a new paradigm must be faced: in classical game theory, intervening agents were humans whose decisions are generally discrete and low dimensional. In AML, decisions are made by algorithms and are usually continuous and high dimensional, e.g. choosing the weights of a neural network. As closed form solutions for Stackelberg games generally do not exist, it is mandatory to have efficient algorithms to search for numerical solutions. We study two different procedures for solving this type of games using gradient methods. We study time and space scalability of both approaches and discuss in which situation it is more appropriate to use each of them. Finally, we illustrate their use in an adversarial prediction problem.Comment: Accepted in ADT Conference 201

Challenge 8: Smart Cybersecurity

Peer reviewe

The ringwork construction and the Ventosiños enclos (Coeses, Lugo). Preliminary study of an Late Bronze ensemble

During the construction works of the a-54 from Lugo to Santiago de Compostela highway, a structure was documented in Ventosiños place, in the parish of Coeses (Lugo), of a kind so far unknown in the context of Galician Prehistory. It was a ring-shaped construction, built with sediment and stone elements, enclosing an inner area in which various pits with lithic and ceramic remains and in situ placed vessels inside were found. In addition, North of this structure, a fence or enclos was located, enveloping an even larger area, in which impressions of diferent morphologies and pits were found. Some of them had perforated disks and in situ placed vessels inside./nPresent analysis is intended to briefly summarize the preliminary data obtained from the archaeological works carried out in the whole ensemble, since the site is still under study.Durante las obras de construcción de la autovía a-54 de Lugo a Santiago de Compostela, se documentó en el lugar de Ventosiños, en la parroquia lucense de Coeses, un tipo de estructura ignota hasta la fecha dentro de la Prehistoria gallega. Se trata de una construcción de morfología anular, erigida con sedimento y elementos líticos, que delimita una superficie interna en la que se localizaron diversas fosas con restos cerámicos y líticos en su interior, y recipientes in situ. Además, al n de dicha estructura, se localizó un cercado o enclos que envuelve un área aún mayor, en la que se documentaron improntas de diferentes morfologías y también fosas, algunas de las cuales presentaban en su interior discos perforados y recipientes./nEl presente análisis tiene como finalidad exponer de forma sucinta los datos preliminares de las actuaciones arqueológicas realizadas en todo el conjunto, dado que el yacimiento se encuentra todavía en fase de estudio

Situación fitosanitaria del arbolado de las dehesas en Extremadura: influencia de las labores selvícolas

En este trabajo se presentan los resultados de una prospección del estado fitosanitario del arbolado en 6.000 árboles de 60 fincas de dehesa extremeñas. Para ello se examinaron 100 árboles por finca, registrándose información sobre 5 variables fisiográficas y de manejo a nivel de finca, y 9 variables individuales de los árboles. Los resultados indican que un 25% de los árboles muestran grandes heridas en el tronco e indicios de haber sufrido penetración de cerambícidos xilófagos, mientras que un 8% de los árboles presenta más del 10% de la copa seca y un 30%ramas secas aisladas. En general, se pone de manifiesto una estrecha asociación entre la incidencia de agentes de deterioro y la edad y ciertas secuelas de manejo inadecuado