The Invariant Two-Parameter Function of Algebras ψ

At present, the research on invariant functions for algebras is very extended since Hrivnák and Novotný defined in 2007 the invariant functions y and j as a tool to study the Inönü–Wigner contractions (IW-contractions), previously introduced by those authors in 1953. In this paper, we introduce a new invariant two-parameter function of algebras, which we call ¯y, as a tool which makes easier the computations and allows researchers to deal with contractions of algebras. Our study of this new function is mainly focused in Malcev algebras of the type Lie, although it can also be used with any other types of algebras. The main goal of the paper is to prove, by means of this function, that the five-dimensional classical-mechanical model built upon certain types of five-dimensional Lie algebras cannot be obtained as a limit process of a quantum-mechanical model based on a fifth Heisenberg algebra. As an example of other applications of the new function obtained, its computation in the case of the Lie algebra induced by the Lorentz group SO(3, 1) is shown and some open physical problems related to contractions are also formulated.Ministerio de Ciencia e Innovación MTM2013-40455-PMinisterio de Ciencia e Innovación FQM-326 (J.N.-V.)Junta de Andalucía FQM-160 (P.P.-F.

Biological welfare during the economic development of the Basque Country : Biscay, 1850-2000

Este trabajo analiza el bienestar biológico en el contexto de la industrialización y el crecimiento económico de Vizcaya. A partir de una muestra de seis localidades, tres industriales y tres agrarias, explora los cambios del bienestar de los jóvenes vascos. Aunque la tendencia de los promedios de estatura en el largo plazo fue ascendente, su evolución fue irregular debido a la influencia de factores medioambientales y socioeconómicos. El deterioro de la talla por cohortes de nacimiento se manifiesta especialmente en tres momentos: durante la fase previa al despegue industrial de la provincia e iniciado el proceso en la década de 1880, en la etapa final de la IGM hasta 1925, y en los años de la Guerra Civil y la posguerra. Se revela igualmente una correlación entre la salud, los salarios reales y la estatura, y se hace un especial seguimiento a lo largo del período del índice de masa corporal para apreciar el grado de robustez de los reclutas vascos.This paper analyses the biological welfare in the context of industrialisation and economic growth in Biscay. It explores the changes in the welfare of young Basques from a sample of six towns, three of them agricultural and the other three industrial. Although the average height had a rising trend in the long term, its evolution was irregular due to the influence of environmental and socioeconomic factors. The decline of height is particularly evident at three stages: firstly, during the pre-industrial boom and once the process had been initiated in the 1880s; secondly, from the end of the First World War until 1925 and, finally, during the years of the Civil War and its aftermath. Moreover, this paper reveals a correlation between health, real wages and height, and it also pays special attention to body mass index (BMI) in order to assess the degree of robustness of the Basque recruits throughout the period under study

Thomas Arnold en la obra de Coubertin. El mito de Arnold

The aim of this essay is to analyse the writings by Coubertin that cover nearly fifty years of his tireless and prolific handwritten activity. In those pieces of writing the Baron expresses his fascination with Arnold as an educator and a reformer. Coubertin states that Arnold’s pedagogy held sport as the central mechanism, placing Arnold in a privileged position in the physical revival of England. However, Arnold was very little (or not at all) interested in sports. The methodology of this study is historical, based on primary and secondary sources. As a conclusion, Arnold and his reforming actions in Rugby were so important for Coubertin that he defined the Headmaster of Rugby public school as the best educator of modern time, responsible for the spiritual and political recovery which took place in England during the second half of the 19th century.El objetivo de este trabajo es analizar escritos de Coubertin, que abarcan casi cincuenta años de su infatigable y prolífica actividad manuscrita, en los que el barón expresa su fascinación por Arnold en sus facetas de pedagogo y reformador. Coubertin sostiene que la pedagogía arnoldiana tenía el deporte como engranaje central, ocupando Arnold un lugar privilegiado en el renacimiento físico de Inglaterra. Sin embargo, Arnold estaba muy poco (o nada) interesado por los deportes. La metodología de este estudio es histórica y se fundamenta en fuentes primarias y secundarias. Como conclusión, para Coubertin fue tan importante Arnold y su acción reformadora en Rugby, que lo definió como el mejor pedagogo de los tiempos modernos y le atribuyó la recuperación espiritual y política que tuvo lugar en Inglaterra desde mediados del siglo XIX

Multi-layered solid-PCM thermocline thermal storage concept for CSP plants. Numerical analysis and perspectives

Thermocline storage concept has been considered for more than a decade as a possible solution to reduce the huge cost of the storage system in concentrated solar power (CSP) plants. However, one of the drawbacks of this concept is the decrease in its performance throughout the time. The objective of this paper is to present a new thermocline-like storage concept, which aims at circumventing this issue. The proposed concept consists of a storage tank filled with a combination of solid material and encapsulated PCMs, forming a multi-layered packed bed, with molten salt as the heat transfer fluid. The performance evaluation of each of the prototypes proposed is virtually tested by means of a detailed numerical methodology which considers the heat transfer and fluid dynamics phenomena present in these devices. The virtual tests carried out are designed so as to take into account several charging and discharging cycles until periodic state is achieved, i.e. when the same amount of energy is stored/released in consecutive charging/discharging cycles. As a result, the dependence of the storage capacity on the PCMs temperatures, the total energy and exergy stored/released, as well as the efficiencies of the storing process are compared for the different thermocline, single PCM, cascaded PCM and the proposed multi-layered solid-PCM (MLSPCM) configurations. The analysis shows that the multi-layered solid-PCM concept is a promising alternative for thermal storage in CSP plants.Peer ReviewedPostprint (author’s final draft

Aspectos que influyen en la planificación del trabajo docente en el aula

Este trabajo desarrolla ideas clave sobre aspectos a considerar en una propuesta de mejora de los procesos de aprendizaje a fin de favorecer con actitudes positivas hacia el aprendizaje y desarrollar experiencias que potencien hábitos de pensamiento en autonomía. El teórico Gagné atribuye a la maduración el cambio de una capacidad o disposición humana en los procesos de aprendizaje y Mattos, por su parte, argumenta que el objetivo específico de la didáctica es la técnica de enseñanza, esto es, la técnica de incentivar y orientar eficazmente a los alumnos en su aprendizaje

Search-Based Mutant Selection for Efficient Test Suite Improvement: Evaluation and Results

Context: Search-based techniques have been applied to almost all areas in software engineering, especially to software testing, seeking to solve hard optimization problems. However, the problem of selecting mutants to improve the test suite at a lower cost has not been explored to the same extent as other problems, such as mutant selection for test suite evaluation or test data generation. Objective: In this paper, we apply search-based mutant selection to enhance the quality of test suites efficiently. Namely, we use the technique known as Evolutionary Mutation Testing (EMT), which allows reducing the number of mutants while preserving the power to refine the test suite. Despite reported benefits of its application, the existing empirical results were derived from a limited number of case studies, a particular set of mutation operators and a vague measure, which currently makes it difficult to determine the real performance of this technique. Method: This paper addresses the shortcomings of previous studies, providing a new methodology to evaluate EMT on the basis of the actual improvement of the test suite achieved by using the evolutionary strategy. We make use of that methodology in new experiments with a carefully selected set of real-world C++ case studies. Results: EMT shows a good performance for most case studies and levels of demand of test suite improvement (around 45% less mutants than random selection in the best case). The results reveal that even a reduced subset of mutants selected with EMT can serve to increase confidence in the test suite, especially in programs with a large set of mutants. Conclusions: These results support the use of search-based techniques to solve the problem of mutant selection for a more efficient test suite refinement. Additionally, we identify some aspects that could foreseeably help enhance EMT

Representational task formats and problem solving strategies in kinematics and work

Previous studies have reported that students employed different problem solving approaches when presented with the same task structured with different representations. In this study, we explored and compared students’ strategies as they attempted tasks from two topical areas, kinematics and work. Our participants were 19 engineering students taking a calculus-based physics course. The tasks were presented in linguistic, graphical, and symbolic forms and requested either a qualitative solution or a value. The analysis was both qualitative and quantitative in nature focusing principally on the characteristics of the strategies employed as well as the underlying reasoning for their applications. A comparison was also made for the same student’s approach with the same kind of representation across the two topics. Additionally, the participants’ overall strategies across the different tasks, in each topic, were considered. On the whole, we found that the students prefer manipulating equations irrespective of the representational format of the task. They rarely recognized the applicability of a ‘‘qualitative’’ approach to solve the problem although they were aware of the concepts involved. Even when the students included visual representations in their solutions, they seldom used these representations in conjunction with the mathematical part of the problem. Additionally, the students were not consistent in their approach for interpreting and solving problems with the same kind of representation across the two topical areas. The representational format, level of prior knowledge, and familiarity with a topic appeared to influence their strategies, their written responses, and their ability to recognize qualitative ways to attempt a problem. The nature of the solution does not seem to impact the strategies employed to handle the problem

Carbene-Controlled Regioselective Functionalization of Linear Alkanes under Silver Catalysis

Control of the regioselectivity in the functionalization of C–H bonds of linear alkanes C2H2n+2 via carbene transfer from diazo compounds is restricted to the use of rhodium-based catalysts, which govern the reaction outcome employing donor–acceptor diazo reagents. At variance with that catalyst-controlled strategy, we present an alternative approach in which employing the appropriate silver complexes containing trispyrazolylborate ligands as catalysts with large differences in their steric and electronic properties, the regioselection is mainly governed by the diazo reagent, which leads to the functionalization of primary or secondary sites of linear alkanes (lacking any activating or directing groups). Donor–acceptor aryl diazoacetates exclusively provide the functionalization of the secondary sites of hexane or pentane, whereas acceptor ethyl diazoacetate leads to an unprecedented level of primary functionalization.We thank to Ministerio de Ciencia e Innovación for Grant PID2020-113797RB-C21. We also thank Junta de Andalucía (P18-1536) and Universidad de Huelva (P.O.Feder UHU- 202024). M.A. thanks Junta de Andalucia for a postdoctoral fellowship

The TpxM Core in Csp3–H Bond Functionalization Reactions: Comparing Carbene, Nitrene, and Oxo Insertion Processes (Tpx = Scorpionate Ligand; M = Cu, Ag)

A comparison between three TpxM‐catalyzed (Tpx = scorpionate ligand; M = Cu, Ag) reactions leading to the functionalization of non‐activated, alkane Csp3–H bonds by carbene, nitrene or oxo insertion is presented. Analogies and differences in these transformations are discussed, including main reactive intermediates, selectivity trends and mechanistic interpretations.Support for this work was provided by the MINECO (CTQ2017-82893-C2-1-R)