Influence of the Compaction Pressure and Sintering Temperature on the Mechanical Properties of Porous Titanium for Biomedical Applications

In the present work, the use of porous titanium is proposed as a solution to the difference in stiffness between the implant and bone tissue, avoiding the bone resorption. Conventional powder metallurgical technique is an industrially established route for fabrication of this type of material. The results are discussed in terms of the influence of compaction pressure and sintering temperature on the porosity (volumetric fraction, size, and morphology) and the quality of the sintering necks. A very good agreement between the predicted values obtained using a simple 2D finite element model, the experimental uniaxial compression behavior, and the analytical model proposed by Nielsen, has been found for both the Young’s modulus and the yield strength. The porous samples obtained by the loose sintering technique and using temperatures between 1000 °C −1100 °C (about 40% of total porosity) are recommended for achieving a suitable biomechanical behavior for cortical bone partial replacement.Ministry of Economy and Competitiveness of the State General Administration of Spain grant MAT2015-71284-

Mass-conservation increases robustness in stochastic reaction-diffusion models of cell crawling

The process of polarization determines the head and tail of single cells. A mechanism of this kind frequently precedes the subsequent cell locomotion and it determines the direction of motion. The process of polarization has frequently been described as a reaction-diffusion mechanism combined with a source of stochastic perturbations. We selected a particular model of amoeboid cell crawling for the motion of Dictyostelium discoideum and studied the interplay between pattern formation and locomotion. Next, we integrated the model in a two-dimensional domain considering the shape deformations of the cells in order to characterize the dynamics. We observed that the condition of pattern formation is finely tuned and we propose a modification based on the use of a mass-conservation constraint to substantially increase the robustness of the mathematical model.Postprint (published version

Failure management insights in 5G using ns-3 network simulator

Failure management has been one of the most researched fields in cellular networks paradigm. Networks operators has experienced many problems on their deployments with each of the past generations. 5G networks aim high to encompass a wide variety of services, which means a large amount of resources on network management and failure resolution. The objective of the present work is to use the previous generation as base and provide, together with the updates on 3GPP specification, insights about what would be the problems that networks will handle. For this, they were identified and categorized some of these failures at the same time their effect on system performance was evaluated.This work was supported by the European Union’s Horizon 2020 research and innovation program under Grant no. 871249, project LOCUS. This work has been also funded by: Junta de Andalucía and ERDF: projects IDADE-5G (UMA18-FEDERJA-201) and OptiRAN5G (UMA18-FEDERJA-174), and postdoctoral grant (Ref., DOC 01154, “selección de personal investigador doctor convocado mediante Resolución de 21 de mayo de 2020”, PAIDI 2020); University of Malaga, through the I Plan Propio de Investigación, Transferencia y Divulgación Científica de la Universidad de Málaga. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

From single to collective motion of social amoebae: a computational study of interacting cells

The coupling of the internal mechanisms of cell polarization to cell shape deformations and subsequent cell crawling poses many interdisciplinary scientific challenges. Several mathematical approaches have been proposed to model the coupling of both processes, where one of the most successful methods relies on a phase field that encodes the morphology of the cell, together with the integration of partial differential equations that account for the polarization mechanism inside the cell domain as defined by the phase field. This approach has been previously employed to model the motion of single cells of the social amoeba Dictyostelium discoideum, a widely used model organism to study actin-driven motility and chemotaxis of eukaryotic cells. Besides single cell motility, Dictyostelium discoideum is also well-known for its collective behavior. Here, we extend the previously introduced model for single cell motility to describe the collective motion of large populations of interacting amoebae by including repulsive interactions between the cells. We performed numerical simulations of this model, first characterizing the motion of single cells in terms of their polarity and velocity vectors. We then systematically studied the collisions between two cells that provided the basic interaction scenarios also observed in larger ensembles of interacting amoebae. Finally, the relevance of the cell density was analyzed, revealing a systematic decrease of the motility with density, associated with the formation of transient cell clusters that emerge in this system even though our model does not include any attractive interactions between cells. This model is a prototypical active matter system for the investigation of the emergent collective dynamics of deformable, self-driven cells with a highly complex, nonlinear coupling of cell shape deformations, self-propulsion and repulsive cell-cell interactions. Understanding these self-organization processes of cells like their autonomous aggregation is of high relevance as collective amoeboid motility is part of wound healing, embryonic morphogenesis or pathological processes like the spreading of metastatic cancer cells.Postprint (published version

Porous Titanium for Biomedical Applications: Evaluation of the Conventional Powder Metallurgy Frontier and Space-Holder Technique

Titanium and its alloys are reference materials in biomedical applications because of their desirable properties. However, one of the most important concerns in long-term prostheses is bone resorption as a result of the stress-shielding phenomena. Development of porous titanium for implants with a low Young’s modulus has accomplished increasing scientific and technological attention. The aim of this study is to evaluate the viability, industrial implementation and potential technology transfer of different powder-metallurgy techniques to obtain porous titanium with stiffness values similar to that exhibited by cortical bone. Porous samples of commercial pure titanium grade-4 were obtained by following both conventional powder metallurgy (PM) and space-holder technique. The conventional PM frontier (Loose-Sintering) was evaluated. Additionally, the technical feasibility of two different space holders (NH4HCO3 and NaCl) was investigated. The microstructural and mechanical properties were assessed. Furthermore, the mechanical properties of titanium porous structures with porosities of 40% were studied by Finite Element Method (FEM) and compared with the experimental results. Some important findings are: (i) the optimal parameters for processing routes used to obtain low Young’s modulus values, retaining suitable mechanical strength; (ii) better mechanical response was obtained by using NH4HCO3 as space holder; and (iii) Ti matrix hardening when the interconnected porosity was 36–45% of total porosity. Finally, the advantages and limitations of the PM techniques employed, towards an industrial implementation, were discussed.Ministry of Economy and Competitiveness of Spain Grant MAT2015-71284-PJunta de Andalucía Grant P12-TEP-1401Comisión Nacional de Investigación, Científica y Tecnológica (CONICYT) of the Chilean government project FONDECYT 1116086

Microgrids Power Quality Enhancement Using Model Predictive Control

In electric power systems, any deviation with respect to the theoretical sinusoidal waveform is considered to be a disturbance in the power quality of the electrical grid. The deviation can alter any of the parameters of the waveform: frequency, amplitude, and symmetry among phases. Microgrid, as a part of the electric power system, has to contribute providing an adequate current waveform in grid connected-mode, as well as to guarantee similar voltage features than the standard requirement given for public distribution grids under normal exploitation conditions in islanded mode. Adequate power quality supply is necessary for the correct compatibility between all the devices connected to the same grid. In this paper, the power quality of microgrids is managed using a Model Predictive Control (MPC) methodology which regulates the power converters of the microgrids in order to achieve the requirements. The control algorithm is developed for the following microgrids working modes: grid-connected, islanded, and interconnected. The simulation results demonstrate that the proposed methodology improves the transient response in comparison with classical methods in all the working modes, minimizing the harmonic content in the current and the voltage even with the presence of non-balanced and non-harmonic-free three-phase voltage and current systems

Vehículos de guiado autónomo (AGV) en aplicaciones industriales: una revisión

A review of the state of the art is presented of the autonomous guidance vehicles (AGV) to transport objects and raw material in industrial applications. The literature review is focus in different topics as the identification of place, application in different environments, vehicle control and description of the software systems used for the programming of mobile robots, according to the requirements or needs to be resolved. Additionally, an analysis is made, based on the aforementioned references, of the contribution made by this type of technologies not only to the industry, but also to other types of business model, such as the health area, the systems of urban transport, etc.Se presenta una revisión del estado del arte de vehículos de guiado autónomo (AGV por sus siglas en inglés: Automated Guided Vehicle) para el transporte de objetos y materia prima en aplicaciones industriales. La revisión de literatura hace énfasis en varios aspectos como la identificación del lugar, aplicación en diferentes entornos, control del vehículo y descripción de los sistemas de software usados para la programación de los robots móviles, de acuerdo a los requisitos o necesidades a resolver. Adicionalmente, se hace un análisis, con base a las referencias citadas, del aporte que hace este tipo de tecnologías no solo a la industria, sino también a otros tipos de modelo de negocio, como lo son el área de la salud, los sistemas de transporte urbano, entre otros. Se presenta una revisión del estado del arte de vehículos de guiado autónomo (AGV por sus siglas en inglés: Automated Guided Vehicle) para el transporte de objetos y materia prima en aplicaciones industriales. La revisión de literatura hace énfasis en varios aspectos como la identificación del lugar, aplicación en diferentes entornos, control del vehículo y descripción de los sistemas de software usados para la programación de los robots móviles, de acuerdo a los requisitos o necesidades a resolver. Adicionalmente, se hace un análisis, con base a las referencias citadas, del aporte que hace este tipo de tecnologías no solo a la industria, sino también a otros tipos de modelo de negocio, como lo son el área de la salud, los sistemas de transporte urbano, entre otros.  A review of the state of the art is presented of the autonomous guidance vehicles (AGV) to transport objects and raw material in industrial applications. The literature review is focus in different topics as the identification of place, application in different environments, vehicle control and description of the software systems used for the programming of mobile robots, according to the requirements or needs to be resolved. Additionally, an analysis is made, based on the aforementioned references, of the contribution made by this type of technologies not only to the industry, but also to other types of business model, such as the health area, the systems of urban transport, etc.

Las narrativas en la construcción de una identidad masculina en adolescentes

"El principal objetivo del presente estudio consistía en indagar como los jóvenes han forjado su identidad masculina, teniendo en cuenta el contexto familiar, escolar y social. El trabajo de investigación fue llevado a cabo con jóvenes entre los 13 y 15 años de la localidad de Kennedy en Bogotá, los cuales hacen parte del programa de ""promotores y promotoras de paz"" de la fundación FUNDECOM. Se realizó una aproximación cualitativa a partir de entrevistas semiestructuradas y construidas a partir del método biográfico, en donde los datos obtenidos, fueron analizados desde la teoría de nuevas masculinidades y psicosocial, teniendo en cuenta los relatos en torno a la subjetividad y al contexto de los participantes. Desde este abordaje se pudo concluir que aun en los jóvenes hay características propias de la masculinidad hegemónica y popular que son aprendidas y legitimadas, pero que a su vez han implicado un proceso de rechazo y crítica en los adolescentes, encontrados nuevas maneras de narrarse.""The main objective in this research was to identify, how the adolescents have shaped their masculine identities taking into account the familiar, social and school context. This research was developed with 13 and 15 years old adolescents from Kennedy, a popular neighborhood in Bogotá, that were part of the ""Promotores y Promotoras de Paz"" program from the FUNDECOM foundation. This study was realized in a qualitative approximation that include structured and semi-structured interviews based on the biographic method. Regarding the collected data, this was analyzed from a new masculinities and a psychosocial perspective, which were taken from the discourses about the subjectivity and context of the participants. This brought to the conclusion that both, the hegemonic and the popular masculinity were learnt and legitimize. However, other narratives have achieved mobilization, allowing talking about their masculine identities from other perspectives. "Psicólogo (a)Pregrad

UE side Application Layer metrics For QoE-based Network Management.

Cellular networks are being improved by the automation of management tasks in order to optimize the performance while improving the efficiency. This is based on the vast amount of data which is available from the network side. Nonetheless, the network side perspective is limited and the focus is being redirected to the user side. Here, Drive Tests are in charge of collecting useful information, but at high costs. Thus, the present work presents a key source of information regarding network management: user side application layer metrics. In this regard, this work exploits this user side data by using different techniques to estimate the users’ quality of experience with the aim of network management.This work was supported by the project MUSE (Massive User Experience Assessment and Prediction for Mobile Networks) - Ref. UMA-CEIATECH-15, and the Spanish Ministry of economic affairs and Digital Transformation and European Union - NextGenerationEU within the framework “Recuperación, Transformación y Resiliencia y el Mecanismo de Recuperación y Resiliencia” - project MAORI, and Univer- sidad de Málaga through the “II Plan Propio de Investigación, Transferencia y Divulgación Científica” This work was possible thanks to the partnership with Metricell Limited to provide a very large dataset of anonymized metrics from real cellular network users. This work has been also funded by: Spanish Ministry of Universities - Ref. FPU20/02863

Characteristics of the nurse cell in different experimental models infected by Trichinella spiralis

Objetivo: Evaluar las características de la célula nodriza en diferentes modelos experimentales. Material y Métodos: Se trabajó con 5 Modelos experimentales; murino (ratón Balb/c, rata Long Evans, Hamster dorado), conejo (Nueva Zelanda), cerdo (York), gato (felis catus) y perro doméstico infectados con Trichinella spiralis, a una dosis estandarizada para todos los modelos, se sacrificaron a las 8 semanas, se tomaron porciones de tejido por triplicado de diafragma, macetero, lengua, pierna, intercostales, orbiculares, cola, cerebro a cada una de estas porciones se les realizó compresión en placa observándolos al microscopio óptico, así mismo se fijaron en formol para realizarle tinción de Hematoxilina-Eosina. A los sueros se les realizó técnica de Inmunoelectrotrasferencia e Inmunofluorescencia para detectar la presencia de anticuerpos de anti-T. spiralis. Resultados: En todos los modelos se desarrolló el ciclo vital del parásito, teniendo mayor carga parasitaria los murinos y conejo y menor cerdo y gato, los tejidos más infectados fueron diafragma, masetero, orbiculares y lengua, en el cerdo se encontró hasta 6 larvas infectantes en una célula nodriza, a nivel cerebro se encontró en rata y en cerdo con hemorragia petequial, y todos tuvieron una respuesta inmune similar. Conclusión: En los huéspedes estudiados Trichinella spiralis tuvo un comportamiento similar, solo es importante mencionar que en cerdo se encontró más de una larva Infectante en la célula nodriza