Hypoxic pre-conditioning increases the infiltration of endothelial cells into scaffolds for dermal regeneration pre-seeded with mesenchymal stem cells.

Many therapies using mesenchymal stem cells (MSC) rely on their ability to produce and release paracrine signals with chemotactic and pro-angiogenic activity. These characteristics, however, are mostly studied under standard in vitro culture conditions. In contrast, various novel cell-based therapies imply pre-seeding MSC into bio-artificial scaffolds. Here we describe human bone marrow-derived MSC seeded in Integra matrices, a common type of scaffold for dermal regeneration (SDR). We show and measured the distribution of MSC within the SDR, where cells clearly establish physical interactions with the scaffold, exhibiting constant metabolic activity for at least 15 days. In the SDR, MSC secrete VEGF and SDF-1α and induce transwell migration of CD34(+) hematopoietic/endothelial progenitor cells, which is inhibited in the presence of a CXCR4/SDF-1α antagonist. MSC in SDR respond to hypoxia by altering levels of angiogenic signals such as Angiogenin, Serpin-1, uPA, and IL-8. Finally, we show that MSC-containing SDR that have been pre-incubated in hypoxia show higher infiltration of endothelial cells after implantation into immune deficient mice. Our data show that MSC are fully functional ex vivo when implanted into SDR. In addition, our results strongly support the notion of hypoxic pre-conditioning MSC-containing SDR, in order to promote angiogenesis in the wounds

Traceable on-machine tool coordinate measurement through the integration of a virtual metrology frame in large machine tools

Metrological traceability and micrometre-level measurement uncertainty are the main research challenges towards traceable coordinate measurement on large machine tools. The impact of time- and space-varying thermal conditions on the machine tool structure is the major uncertainty contributor to the uncertainty budget. Aiming to minimise this influencing factor, this research proposes the use of integrated multilateration as a virtual metrology frame in combination with the machine tool controller information to characterise the position and orientation of every coordinate measurement performed by the machine tool. Experimental results demonstrate that measurement uncertainty is within an 18-micrometre range and assess the required metrological traceability

Hybrid optimization approach for the design of mechanisms using a new error estimator

A hybrid optimization approach for the design of linkages is presented. The method is applied to the dimensional synthesis of mechanism and combines the merits of both stochastic and deterministic optimization. The stochastic optimization approach is based on a real-valued evolutionary algorithm (EA) and is used for extensive exploration of the design variable space when searching for the best linkage. The deterministic approach uses a local optimization technique to improve the efficiency by reducing the high CPU time that EA techniques require in this kind of applications. To that end, the deterministic approach is implemented in the evolutionary algorithm in two stages. The first stage is the fitness evaluation where the deterministic approach is used to obtain an effective new error estimator. In the second stage the deterministic approach refines the solution provided by the evolutionary part of the algorithm. The new error estimator enables the evaluation of the different individuals in each generation, avoiding the removal of well-adapted linkages that other methods would not detect. The efficiency, robustness, and accuracy of the proposed method are tested for the design of a mechanism in two examples.This paper has been developed in the framework of the Project DPI2010-18316 funded by the Spanish Ministry of Economy and Competitiveness

Hugo Chávez: una década en el poder

Una década de Hugo Chávez Frías y su proyecto político en Venezuela trajo consigo un cambio de paradigmas que llama la atención de la sociedad en general. Este libro es el resultado del esfuerzo conjunto de un grupo de académicos de distintas nacionalidades que desde sus líneas de investigación realizan análisis que le brindan al lector elementos para comprender de manera global lo que significa una década de gobierno del Presidente Chávez en Venezuela.Este libro es el resultado del esfuerzo conjunto de un grupo de académicos de distintas nacionalidades que desde sus líneas de investigación realizan análisis que le brindan al lector elementos para comprender de manera global lo que significa una década de gobierno del Presidente Chávez en Venezuela

Learning Styles Preferences of Spanish Students between 11 and 15 years of age

Los estilos de aprendizaje constituyen las preferencias de una persona para recibir, recopilar, procesar e interpretar información. Para medir este constructo se han diseñado diversos instrumentos, entre ellos el Index of Learning Styles (ILS), que es utilizado en este trabajo. El objetivo fue analizar las preferencias de estilos de aprendizaje en el estudiantado español de 11 a 15 años respecto a algunas variables sociodemográficas partiendo de un diseño no experimentaltransversal. Los resultados muestran que el alumnado tiene un estilo predominantemente activo, sensitivo, visual y secuencial; siendo el canal preferido para recibir la información el visual frente al verbal. La tendencia de las alumnas al estilo reflexivo es mayor que la de los alumnos. Quienes estudian en centros públicos tienden a ser más visuales, intuitivos y globales en su aprendizaje que quienes asisten a centros concertados. Aquellos pertenecientes a localidades de mayor tamaño (zonas urbanas) tienden a tener estilos de aprendizaje más sensitivos, verbales y secuenciales, mientras que en las zonas rurales los aprendizajes son de carácter ligeramente más intuitivo, visual y global. El tamaño del efecto es pequeño en la comparativa por sexo, por titularidad del centro y por entorno. Sin embargo, en cuanto al curso escolar el tamaño del efecto es moderado, el estudiantado de cursos superiores tiende a ser más sensitivo y visual y el de cursos inferiores más intuitivo y, sobre todo, más verbal. El conocimiento sobre los estilos de aprendizaje permite diseñar y adaptar los procesos formativos a las diferencias existentes en el aula.Learning styles are personal preferences for receiving, collecting, processing, and interpreting information. To assess this construct, various instruments have been designed, including the Index of Learning Styles (ILS), which is used in this study. The aim of this paper was to analyze the learning style preferences of Spanish students aged 11 to 15 years according to some sociodemographic variables, using a non-experimental cross-sectional design. The results indicate that the students have a primarily active, sensitive, visual, and sequential style; the preferred channel for receiving information is visual versus verbal. The prevalence of reflective learning styles is higher in female students than in male students. Those who study in public schools tend to be more visual, intuitive, and global in their learning processes than those who attend subsidized schools. Those in larger localities (urban areas) tend to have more sensitive, verbal and sequential learning styles, while in rural areas, the process of learning is slightly more intuitive, visual and global. The effect size is small regarding gender, school ownership and environment. However, in terms of school year, the effect size is moderate: students in higher grades tend to be more sensitive and visual than those in lower grades, who are more intuitive and, above all, more verbal. Knowing about learning styles is useful to design and adapt the training processes to the classroom differences

Learning Styles Preferences of Spanish Students between 11 and 15 years of age

Learning styles are personal preferences for receiving, collecting, processing, and interpreting information. To assess this construct, various instruments have been designed, including the Index of Learning Styles (ILS), which is used in this study. The aim of this paper was to analyze the learning style preferences of Spanish students aged 11 to 15 years according to some sociodemographic variables, using a non-experimental cross-sectional design. The results indicate that the students have a primarily active, sensitive, visual, and sequential style; the preferred channel for receiving information is visual versus verbal. The prevalence of reflective learning styles is higher in female students than in male students. Those who study in public schools tend to be more visual, intuitive, and global in their learning processes than those who attend subsidized schools. Those in larger localities (urban areas) tend to have more sensitive, verbal and sequential learning styles, while in rural areas, the process of learning is slightly more intuitive, visual and global. The effect size is small regarding gender, school ownership and environment. However, in terms of school year, the effect size is moderate: students in higher grades tend to be more sensitive and visual than those in lower grades, who are more intuitive and, above all, more verbal. Knowing about learning styles is useful to design and adapt the training processes to the classroom differences.Los estilos de aprendizaje constituyen las preferencias de una persona para recibir, recopilar, procesar e interpretar información. Para medir este constructo se han diseñado diversos instrumentos, entre ellos el Index of Learning Styles (ILS), que es utilizado en este trabajo. El objetivo fue analizar las preferencias de estilos de aprendizaje en el estudiantado español de 11 a 15 años respecto a algunas variables sociodemográficas partiendo de un diseño no experimental-transversal. Los resultados muestran que el alumnado tiene un estilo predominantemente activo, sensitivo, visual y secuencial; siendo el canal preferido para recibir la información el visual frente al verbal. La tendencia de las alumnas al estilo reflexivo es mayor que la de los alumnos. Quienes estudian en centros públicos tienden a ser más visuales, intuitivos y globales en su aprendizaje que quienes asisten a centros concertados. Aquellos pertenecientes a localidades de mayor tamaño (zonas urbanas) tienden a tener estilos de aprendizaje más sensitivos, verbales y secuenciales, mientras que en las zonas rurales los aprendizajes son de carácter ligeramente más intuitivo, visual y global. El tamaño del efecto es pequeño en la comparativa por sexo, por titularidad del centro y por entorno. Sin embargo, en cuanto al curso escolar el tamaño del efecto es moderado, el estudiantado de cursos superiores tiende a ser más sensitivo y visual y el de cursos inferiores más intuitivo y, sobre todo, más verbal. El conocimiento sobre los estilos de aprendizaje permite diseñar y adaptar los procesos formativos a las diferencias existentes en el aula

Zebrafish as an Emerging Model Organism to Study Angiogenesis in Development and Regeneration.

Angiogenesis is the process through which new blood vessels are formed from preexisting ones and plays a critical role in several conditions including embryonic development, tissue repair and disease. Moreover, enhanced therapeutic angiogenesis is a major goal in the field of regenerative medicine and efficient vascularization of artificial tissues and organs is one of the main hindrances in the implementation of tissue engineering approaches, while, on the other hand, inhibition of angiogenesis is a key therapeutic target to inhibit for instance tumor growth. During the last decades, the understanding of cellular and molecular mechanisms involved in this process has been matter of intense research. In this regard, several in vitro and in vivo models have been established to visualize and study migration of endothelial progenitor cells, formation of endothelial tubules and the generation of new vascular networks, while assessing the conditions and treatments that either promote or inhibit such processes. In this review, we address and compare the most commonly used experimental models to study angiogenesis in vitro and in vivo. In particular, we focus on the implementation of the zebrafish (Danio rerio) as a model to study angiogenesis and discuss the advantages and not yet explored possibilities of its use as model organism

Zebrafish as an Emerging Model Organism to Study Angiogenesis in Development and Regeneration.

Angiogenesis is the process through which new blood vessels are formed from preexisting ones and plays a critical role in several conditions including embryonic development, tissue repair and disease. Moreover, enhanced therapeutic angiogenesis is a major goal in the field of regenerative medicine and efficient vascularization of artificial tissues and organs is one of the main hindrances in the implementation of tissue engineering approaches, while, on the other hand, inhibition of angiogenesis is a key therapeutic target to inhibit for instance tumor growth. During the last decades, the understanding of cellular and molecular mechanisms involved in this process has been matter of intense research. In this regard, several in vitro and in vivo models have been established to visualize and study migration of endothelial progenitor cells, formation of endothelial tubules and the generation of new vascular networks, while assessing the conditions and treatments that either promote or inhibit such processes. In this review, we address and compare the most commonly used experimental models to study angiogenesis in vitro and in vivo. In particular, we focus on the implementation of the zebrafish (Danio rerio) as a model to study angiogenesis and discuss the advantages and not yet explored possibilities of its use as model organism