Emprendimiento y crecimiento económico: una visión desde la literatura y los principales indicadores internacionales (Estudios)

The article makes a critical analysis of the theoretical and empirical work on the relationship between entrepreneurial capital and economic growth. For this, a review of the entrepreneurship literature between 2004 and 2014 is carried out; based on the research questions on the impact of entrepreneurial capital on economic growth and the conceptualization and modes of operationalization of entrepreneurial capital, based on ten international indicators. The article suggests that entrepreneurial capital has a positive impact on economic growth, which is very sensitive to diversity, ambiguity and insufficiency of the different ways of operating it.El artículo realiza un análisis crítico de los trabajos teóricos y empíricos sobre la relación entre el capital emprendedor y el crecimiento económico. Para ello se realiza una revisión de la literatura sobre emprendimiento entre 2004 y 2014, a partir de las preguntas de investigación sobre el impacto del capital emprendedor en el crecimiento económico y la conceptualización y modos de operacionalización del capital emprendedor, que toman como base diez indicadores internacionales. Concluye que el capital emprendedor tiene impacto positivo en el crecimiento económico, muy sensible a la diversidad, ambigüedad e insuficiencia de los distintos modos de operacionalizarlo

Procedimientos utilizados por niños tee savi de primaria al resolver problemas aritméticos

El escrito describe una investigación de corte descriptiva e interpretativa que responde a la pregunta: ¿cuáles son las estrategias que utilizan los niños Tee Savi (mixtecos) de primaria cuando resuelven problemas aritméticos formales y prácticos? Cuestión que creemos pertinente ante la ausencia de investigaciones con este interés, enfocadas a dicha población étnica del estado de Guerrero, México. Resulta también relevante, por la importancia que cobra la interculturalidad en los planes y programas de estudio en vigor (SEP, 2011). Realizamos un estudio de casos múltiples donde participan alumnos de 4°, 5° y 6° grado de primaria, cuyas edades oscilan entre 9 a 13 años. Como instrumentos de recolección de datos se utilizó: cuestionarios (escrito en castellano) y entrevistas grupales (en la lengua materna del estudiante). Los resultados dan cuenta que existe una diferencia marcada entre las estrategias usadas en ambos tipos de problemas

Spectroscopic Determination of Aboveground Biomass in Grasslands Using Spectral Transformations, Support Vector Machine and Partial Least Squares Regression

[EN] Aboveground biomass (AGB) is one of the strategic biophysical variables of interest in vegetation studies. The main objective of this study was to evaluate the Support Vector Machine (SVM) and Partial Least Squares Regression (PLSR) for estimating the AGB of grasslands from field spectrometer data and to find out which data pre-processing approach was the most suitable. The most accurate model to predict the total AGB involved PLSR and the Maximum Band Depth index derived from the continuum removed reflectance in the absorption features between 916–1,120 nm and 1,079–1,297 nm (R2 = 0.939, RMSE = 7.120 g/m2). Regarding the green fraction of the AGB, the Area Over the Minimum index derived from the continuum removed spectra provided the most accurate model overall (R2 = 0.939, RMSE = 3.172 g/m2). Identifying the appropriate absorption features was proved to be crucial to improve the performance of PLSR to estimate the total and green aboveground biomass, by using the indices derived from those spectral regions. Ordinary Least Square Regression could be used as a surrogate for the PLSR approach with the Area Over the Minimum index as the independent variable, although the resulting model would not be as accurate.SIThis research has been partially funded by the Junta de Castilla y Leó

Obesity generates metabolic alterations in the myocardium leading to changes in mitochondrial membrane permeability

Digitalitzat per Artypla

Ride-hailing services: Competition or complement to public transport to reduce accident rates. The case of Madrid

Introduction: The transport and mobility sector is experiencing profound transformations. These changes are mainly due to: environmental awareness, the increase in the population of large urban areas and the size of cities, the aging of the population and the emergence of relevant technological innovations that have changed consumption habits, such as electronic commerce or the sharing economy. The introduction of new services such as Uber or Cabify is transforming urban and metropolitan mobility, which has to adapt to this new scenario and the very concept of mobility. Objective: Thus, the purpose of this study was to evaluate whether ride-hailing platforms substitute or complement public transport to reduce accident rates, considering the two basic transport zones of Madrid: “The Central Almond” and the periphery. Methods: The data were collected from the 21 districts of Madrid for the period 2013–2019, and they were analyzed by a Random Effects Negative Binominal model. Results: The results obtained in this study suggest that since the arrival of Uber and Cabify to the municipality of Madrid the number of fatalities and serious injuries in traffic accidents has been reduced. Traffic accidents on weekends and holidays, with at least one serious injury or death, have also been reduced. However, the number of minor injuries has increased in the central districts of Madrid. Conclusion: Overall, what was found in this study supports the hypothesis that these services replace the urban buses. However, these services improve the supply to users with greater difficulties to access taxis or public transport, constituting an alternative mode of transport for high-risk drivers. Therefore, such findings may be quite useful for policy makers to better define regulatory policies for these services.María Flor García is currently developing her doctoral thesis on sharing economy and mobility and received an FPU grant from the University of Alicante: UAFPU2018–028