Effects of Uniaxial Cyclic Strain on Endothelial Progenitor Cells

Despite the high prevalence of calcific aortic valve disease (CAVD), the underlying mechanisms of pathogenesis have not been found yet. Therefore, it is extremely important to study CAVD and understand how it develops. For this matter, we decided to study the potential of endothelial progenitor cells (EPCs) for use in tissue-engineered models of heart valves. EPCs were chosen as the cell source of interest for this study due to their high neovascularization potential and use in regenerative medicine and cardiovascular tissue engineering. In this project, we aimed to engineer the microenvironment of cells that are involved in the formation of heart valves. We hypothesized that cyclic strain induces EPCs to undergo differentiation, which will depend on the applied strain, culture media components and culture duration. EPCs isolated from human umbilical cord blood expressed endothelial cell markers CD31 and vascular endothelial growth factor receptor 2 (VEGFR2), and the progenitor cell marker CD34. The cells did not express the mesenchymal marker α-smooth muscle actin (α-SMA). EPCs showed an endothelial behavior demonstrated by the uptake of acetylated-low density lipoprotein (Dil-Ac-LDL), and a vasculogenic potential demonstrated by tube formation. The cells were subjected to 20% strain rates by utilizing a cyclic uniaxial biostretcher for 7 days and showed a mild expression of α-SMA. Considering these events, EPCs were subjected to 20% strain for longer periods of time (1, 2, and 3 weeks) and showed maintained CD31 expression, no α-SMA expression, and increased CD34 expression suggesting an increased vascular-like behavior after strain

The impact of collective actions on rural farming incomes in Peru: The case of the APOMIPE program

56 p.Peru continues fighting back against the persistently high rural poverty. Recent data suggest that 75% of the rural population is below the poverty line (Jonasson, 2009). Even though agricultural development traditionally has been the main ingredient in rural development strategies, scholars have for long emphasized the need for diversified approaches to fighting rural poverty in order to take the heterogeneity of the rural population into account. In this sense, several strategies have been applied in order to improve agricultural productivity. Collective actions rise as an alternative to alleviate the poverty situation, especially in rural areas. An interesting initiative has been implemented since 2005 in Peru: the APOMIPE Program, which focused on the conformation of small entrepreneurial networks, adapting the "MSE Networking Methodology”. The entrepreneurial networks shows an experience in which farmers are able to improve their productivity, have more access to markets, and improve the standard way of living of the households. In order to measure the effects of the APOMIPE Program on the farmers’ income and to analyze its determinants, it will be used a model that shows the relationship between farmers’ incomes and key factors during the implementation of the Program such as collective actions. The main purpose of this study will be to analyze the effects on the beneficiaries’ incomes who participated in the Program and who were involved in the entrepreneurial networks model. The specific objectives will look for determining the main factors that have contributed to the increase of investment to carry out collective actions and to analyze the impact of collective investments on the farmers’ incomes This study attempts to study the impact of the APOMIPE Program on the beneficiaries through quantitative and qualitative method by using a survey carried out before (a baseline was developed in 2005) and after the Program (the Program ended in 2011). It will be analyzed the determinants of farm income among the farmers who participated in APOMIPE. In this model, it will used be a household resource set that consists of human capital (e.g., education, experience, and demographic attributes), and social capital (e.g., access to social networks and institutions), which affects the farmers’ incomes. In this model, the links between a household’s resources and income can be considered as a production process, with resources corresponding to factors of production and income as the output. Focus group reports made by the Program before and after its execution will be used. There will be carried out interviews to key agents such as governmental representatives and other Non Governmental Organization’s (NGO) functionaries that have implemented similar projects in the regions where the Program was executed. By using qualitative methods, not only provide qualitative measures of impact, but also help in the deeper interpretation of results obtained from a quantitative approach by giving more reliability on the processes and causal relationships. Since one of the specifics objectives is to measure the influence of social factors on the process of conformation of entrepreneurial networks, it will be important to determine if those factors have really impacted in the conformation of networks through the perception of the main representatives that have been involved during the process of the Program. Through the interviews, there will be a closer perception of those functionaries that have worked directly with the farmers. Another objective of the interviews, that will enrich the qualitative sources, is to determine the main elements that have been successful for similar Programs (in terms of incomes or productivity) as well as the obstacles that had to be faced by other ONGs and Government’s Programs. This information will be complementary in order to identify the determinants of farmers’ incomes that could not have been recognized by the APOMIPE Progra

Intersección de la matemática educativa y las ciencias sociales: el caso de los seguros de vida

La enseñanza de la Economía implica un problema pedagógico didáctico: ¿Qué y cuánta Matemática resulta imprescindible en las teorías económicas? Una respuesta exige una profunda reflexión sobre la formación matemática de los profesores de Economía y de investigaciones en Educación Matemática. Este trabajo muestra, de manera didáctica, la medición de la incertidumbre que involucran los seguros de vida. El asegurador determina el precio de la cobertura que brinda un seguro por medio de las Tablas de Mortalidad, estudiadas por la Matemática Actuarial. Este tema evidencia la intersección de problemas económicos y poblacionales, utilizando conceptos matemáticos aplicables a la Educación Matemática en Economía

Filosofía de la matemática

En este curso corto se discurre sobre el objeto, metodología, deductibilidad y validación de los conocimientos matemáticos. Se expone la interrelación de tres ámbitos: ontológico, lingüístico y lógico-formal, sistematizados en tres grandes líneas: el logicismo, el formalismo y el intuicionismo. Se desarrolla la historia de la Geometría para mostrar que los fundamentos del espacio geométrico son independientes del espacio físico, tal como aparece en las Geometrías euclideanas y no euclideanas. Como cualquier sistema axiomático que contenga a la aritmética elemental deriva en paradojas, se comprueban los metateoremas de la consistencia y la completitud, desarrollados por Gödel

The MRPC-based ALICE Time-Of-Flight detector: status and performance

The large Time-Of-Flight (TOF) array is one of the main detectors devoted to charged hadron identification in the mid-rapidity region of the ALICE experiment at the LHC. It allows separation among pions, kaons and protons up to a few GeV/c, covering the full azimuthal angle and -0.9 < eta < 0.9. The TOF exploits the innovative MRPC technology capable of an intrinsic time resolution better than 50 ps with an efficiency close to 100% and a large operational plateau; the full array consists of 1593 MRPCs covering a cylindrical surface of 141 m2. The TOF detector has been efficiently taking data since the first pp collisions recorded in ALICE in December 2009. In this report, the status of the TOF detector and the performance achieved for both pp and Pb--Pb collisions are described.Comment: 4 pages, 6 figure

El aprendizaje de la matemática y sus referencias semióticas

Las ciencias fácticas tienen contenido existencial que se corresponde con la realidad. En cambio, las ciencias formales, desde el siglo XIX, sostienen una dimensión sintáctico-formalista, sin contenidos semántico y pragmático. Por lo cual la simbología matemática se presenta como vacía, o sea que no habla de nada. Esto daría derecho al alumno a cuestionar “Y... aprender este lenguaje que no habla de nada, ¿de qué me sirve?” El profesor se verá obligado a demostrar que este lenguaje es fecundo, que puede hablar de todo y que se constituye en la estructura del lenguaje científico porque, precisamente, no habla de nada específico. En este trabajo reflexionamos acerca de las relaciones semánticas y pragmáticas que encierra la Matemática pura y que nos conduce a consideraciones de la ontología matemática, correlacionando genéticamente el pensamiento concreto y el abstracto