Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

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Due to the scarcity and high transportation costs of stone aggregates in the east and northeast of Bolivia, different alternatives have been sought for their partial or complete replacement in the construction industry and, specifically, to produce concrete. The objective of this research is to evaluate the workability, compressive strength, and ultrasonic pulse velocity (UPV) of concrete produced entirely with coarse lateritic aggregates and a commercial superplasticizer additive. Using the IPT/EPUSP method, concrete with coarse lateritic aggregate was dosed for 30 MPa (design compressive strength). Five different percentages of additive (by weight of cement) were considered: 0% (reference), 0.6, 0.8, 1 and 1.2%. Although the superplasticizer additive improves workability at higher percentages, the mixtures with 0.6, 0.8 and 1% presented higher compressive strength and VPU, when compared to the reference (0%). 1.2% of additive presented the lowest values ​​of compressive strength and VPU. The use of additives, in this case superplasticizer, is beneficial for the workability and compressive strength of lateritic concrete, but the most appropriate content for its use must be defined.

The objective of the research was to carry out a repeatability and reproducibility study in representative samples of small wooden specimens from Spathodea campanulata, Fraxinus americana and Albizia Plurijuga. The experimental strategy assumes two stages. The first consisted of the analysis of the results of the frequencies measured in the three angiosperm species. Its objective was to validate the homogeneity and representativeness of the woods under study. The second stage was oriented to the study of the variations of the frequency results. Its objective was to build repeatability and reproducibility tables and their analysis of variance. A completely randomized and balanced design was prepared. The experimental unit consisted of three homogeneous groups of 40 test tubes of each species. For each species studied, crossover repeatability and reproducibility studies were carried out. The results indicate that for S. campanulata, 97.7% of the total variance is due to the instrument while 2.3% to differences between operators; for F. americana, 99.2% of the total variance is due to the instrument and 0.8% to differences between operators, while for A. plurijuga, 100% of the total variance is due to the instrument while there is no variability due to differences between operators.

This research aims to determine the effects of the use of curing products in hydraulic concrete through laboratory conditions. Although research and technical specifications of curing products indicate improvements in concrete curing, their use and possible advantages must be experimentally verified for the conditions and types of concrete manufactured in Costa Rica. Three types of curing products are used, the first corresponds to a transparent silicate-based curing product that does not produce membrane (C1), the second is a resin-based membrane-forming curing product (C2) and the third is a product Colloidal solution based film-forming curing agent (C3). Through laboratory tests, the compressive strength, modulus of rupture and change in length (expansion or contraction) of concrete are determined for different curing conditions. In general, the results indicate that curing products, at any age of application, do not reduce the expansion or contraction of concrete. For curatives to be adequately effective in developing resistance to shrinkage and flexure in concrete, it must be cured with water for a minimum of three days prior to application of the product. The results suggest better results when applying the curing product 7 days after keeping the specimens in the wet room. 

The demands for construction materials are increasing, their sources are scarce and the management of construction and demolition waste is very complex. The research that supported this article sought to study the characteristics of coarse aggregate for construction from civil works waste, and compare them with traditional virgin aggregates, in order to assess their possible use. We worked with three sources of raw material for recycling: masonry walls, precast tiles, and cast-in-place concrete (test cylinders); all facilitated by the LanammeUCR. The standards established by INTECO were followed, both for the characterization of the recycled aggregates and for the mix designs. Three different percentages of recycled coarse aggregate were used in the mixtures, substituting the natural one. The results showed small variations regarding the behavior of the virgin aggregate, especially in absorption, unit weight and wear. Very favorable results were obtained in terms of the compressive strength of the concretes with recycled coarse aggregate, always contemplating a mix design that adjusted to its characteristics. Among the limitations is that the durability of manufactured concrete was not studied; recycled fine aggregate was not used either. Both phenomena will be addressed in future research. At the end of the investigation, it is concluded that the recycling of coarse aggregate is technically feasible.

In this investigation, the performance and cost of workforce, material, and equipment in the application of plaster with industrialized mortar were estimated. The measurements were made in three housing projects of one and two levels, located within Alajuela, Heredia, San José or Cartago, Costa Rica. In the first two, mortars of different brands were used, however, the application methodology was manual in both cases. In the third project the same mortar was used as one of the previous projects, but it was applied mechanically. For the data analysis obtained, the statistical student-t test was used, with a reliability of 90%. It should be noted that the results are valid only for projects with characteristics like the ones used in this study. According to the results, the cost of the plastering applied manually is very similar to the one applied with a sprayer machine, since the savings in workforce cost is approximately equivalent to the amount necessary to amortize the equipment and the additional cost of the projectable material.

Este artículo tiene por objeto mostrar los retos y dificultades que enfrentan los alumnos de nivel primario en el municipio de Tecpan de Galeana, Guerrero, derivados de la pandemia de COVID-19, ya que han sido afectados de manera importante, porque el Estado mexicano se ha visto rebasado por los efectos negativos de la pandemia, y con ello, diversos educandos no han podido acceder ni continuar con su formación. La investigación es de tipo sociojurídica, por el nivel y temporalidad desarrollada es de tipo descriptiva, por la finalidad de la investigación es aplicada; también, se empleó el método inductivo y el paradigma interpretativo. Las técnicas e instrumentos empleados fueron: recolección de datos directos de la realidad, encuestas y entrevistas, libros, legislación, jurisprudencia, revistas, entre otros. Para ello, conoceremos cómo es la realidad de los niños de nivel de primaria que residen en dicho municipio, de igual manera se conocerán las medidas que el Estado mexicano ha tomado al respecto y qué tan efectivas han sido; además se consultarán todas las recomendaciones que han realizado diversos organismos internacionales. Entre las principales conclusiones se encontró que es indudable que el derecho humano a la educación primaria es reconocido no solo por organismos internacionales, sino que, por la Constitución Política de México, así como, por las constituciones Estatales y leyes generales; por lo tanto, el Estado tiene la obligación de cumplir con su garantía. Se determinó que el Estado mexicano no supo tomar las medidas adecuadas, y no invirtió lo suficiente para hacer frente a las dificultades que se derivaron en materia educativa a raíz de la COVID-19. Aunado a esto, muchos padres de familia no pudieron solventar los diversos gastos que implica la educación a distancia, por el desempleo que desencadenado.

Este artículo presenta los resultados de una investigación donde se analizó la construcción del enemigo desde contextos educativos en Colombia. La metodología empleada fue la investigación acción (IA) utilizando entrevistas que, desde el análisis crítico del discurso (ACD), permitieron evidenciar algunas prácticas y discursos que establecen imaginarios sobre el otro ser, lo que al final ayudó a comprender la necesidad de promover nuevas estrategias que permitan la deconstrucción de estas prácticas que faciliten procesos para afianzar el desarrollo de la cátedra de paz, lograr una mayor vinculación de la familia al quehacer educativo y vincular el contexto social a la hora de implementar alguna estrategia pedagógica favorecedora de una cultura de paz más sólida desde los territorios.

We know that science is a precious ally for the judge in the search for truth. But we also know that every coin has its flipside. Science can in fact constitute a false ally for the judge, dangerously channeling the process towards judicial error. The matter is well known. Criminal justice now draws heavily on the results of science, but has to deal with its overt fallibility. Often the process becomes the place where experts and consultants reveal the gaps in those same disciplines that should instead correctly orientate the decisions of criminal judges. Therefore, the Criminal trial always needs witnesses. Especially witnesses against the accused, of course. However testimonial evidence as a fundamental judicial decision making tool is in crisis today. A crisis that has come about as a result of the downsizing of the right of the accused to effectively cross-examine the witnesses testifying against him (or her), thereby reducing the chances for the judge to perceive the witness's story in the best possible way. Hence the risk of significantly lowering the quality standard of criminal sentences. The crisis of testimony in the criminal trial can be attributed to two factors. The first reason. The multiplication of protected witnesses on the trial scene. Figures who, as a sort of counterpart for their contribution to the assessment, require high, constant and diversified levels of protection: "fragile" and vulnerable people, minors, the mentally ill, witnesses of justice, or "anonymous" witnesses" (undercover agents). As we can see, as a rule, we are dealing with persons who usually testify against the accused. At the level of European and Italian law and jurisprudence the trend is clear. The needs of protection for these categories of witnesses result in a reduction in the number of hearings, and therefore the opportunities for dialectical confrontation between the accused and the witness. The may also result in the push to "personalization" of the methods used for that confrontation, by adapting it to the protection needs to be met.  In some cases those forms of protection could be used to get more genuine information from the witness, but we also cannot underestimate the opposite risk of obtaining qualitatively less reliable statements: because they might too conditioned by those protection needs, precluding the defender of the accused the possibility of deepening some controversial points. The second reason. At the national and European political level, the idea now prevails that the speed of Criminal justice is the primary instrument by which to calibrate the standard of reliability and solidity of an economically advanced State. This mainstream perspective is the fruit of an exasperated and erroneous conception of the principle of the reasonable duration of the trial (Art. 6 par. 1 ECHR and Art. 111 par. 2 Italian Constitution). The time factor is now an absolute, apical and absorbing value in the Criminal trial, which seems capable of negatively impacting the quality of the witness evidence as well: we refer, in particular, to the recent so-called Cartabia Reform of the Italian Code of Criminal Procedure, where a weakening of the fundamental principle of immediacy is clearly perceptible. That is, the judge attending the construction of the oral evidence and the judge who must adopt the judgment must be the same. When the trial judge changes, the idea is that immediacy can be easily replaced by technology (the audiovisual recording of the testimony before the first judge and subsequent viewing of the recording by the new judge).

This paper provides an overview of several central topics for comparative research on wrongful convictions and prosecutions (near misses). The work addresses three issues: studies that attempt to establish the quantity or frequency of errors; research that investigates the factors that increase the likelihood of their occurrence; and, finally, research on the mechanisms for correcting and compensating them. In each area, advances in available knowledge are identified, but also that we are still far from having all the information that would be required. We aim to serve as an introduction to this special issue of the RBDPP and as a starting point for those who wish to know state of the art on the subject.