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

Asphalt has complex chemical and physical compositions that normally vary with the source of crude oil. Its composition is based on approximately 84% C, 10% H2, 1% O2 and 5% trace elements such as S, Ni, V and Fe. This is the development of a new method to quantify V, Ni, Zn and Fe on asphalt AC-30 by atomic absorption spectroscopy. These metals were detected qualitatively with a higher intensity in an X-ray analysis by fluorescence in an electron scanning microscope. Some metals found in asphalt may have a catalytic effect on the oxidation of asphalt.The research proposes a treatment process of up to 2 g of asphalt, which is based on dilution with mineral spirits in volumetric flasks with the aid of an ultrasonic bath to lighten the dilution. The parameters of optimization of the method are dictated by looking for the adequate instrumental data in the atomic absorption equipment to obtain the highest possible absorbance in the alignment of both the burner and the hollow cathode and deuterium lamps; In addition to the optimization of the flame and the flow of the nebulizer. The calibration curves of each metal were performed with a hydrocarbon-based standard to measure metal concentrations in asphalt in mg / kg with a linear correlation coefficient of at least 0,995. The asphalt recovery study is performed with the addition of a quantity of the metals directly to the asphalt matrix aliquots. The concentrations obtained for Ni were 70, V 330, Zn 24 and for Fe 10 ppm, which presented a relative standard deviation of less than 1%, indicating that measurements of the same sample are accurate and have little dispersion between them. The average recoveries were 99,17% for Ni, 100,30% V, 92,26% Zn and 97,72% Fe. These results indicate that the method is reliable for the quantification of metals by the atomic absorption technique; values greater than 100% are given by readings of absorbances higher than expected or by generation of false positives in the technique. 

The expansion of the accelerated test in mortar bars test immersed for 14 days in an aggressive solution (IRAM 1674) as well as the kinetic analysis according to RILEM AAR-2 recommendations for the study of the potencial deleterious of the aggregate in the alkali-silica reaction are presented in this work. The main objective is to contribute to the interpretation of the test results based on the analysis of the growth in expansion with the time of immersion (kinetic analysis) and in this way, get more reliability. The kinetic analysis consists in adjusting by least squares fit of the experimental data of expansion to a known mathematical model (model KAMJ), where the parameters lnk and M are obtained from. The kinetic parameters lnk and M are associated with the behavior of the reaction. Although a limit value for lnk of -6 is proposed in the literature (lower values are non-reactive aggregates and higher values are deleterious aggregate), from the analysis of the experimental data it was observed that low values of this parameter could be associated with not asymptotic growth of expansion and, therefore, the aggregates presents a deleterious behavior. The lnk/M coefficient is considered a good indicator to evaluate the behavior of the aggregate. However, in order to define a limit value for lnk/M coefficient, it is necessary to establish a correlation with the tests on long-term concrete prism (1 year or more) or the field experience of the aggregate behavior.

The composition of the hot asphalt mixture used for pavements is defined according to a design that try to meet the performance according the project in which it is to be used. Since asphalt is the binding material that provides cohesion and adhesion to the mixture, it is important to be able to quantify if the mixture produced contains the amount of asphalt established in the mix design, for that different tests have been developed to determine the content of asphalt. Although the purpose of the test methods is the same, there are doubts about the accuracy of some of them, and especially about the correlation between test procedures. This study aims to provide real results of an asphalt mix produced in a production plant, which is analyzed using the different methods and equipment to compare them with the production data and thus determine the precision and accuracy of each procedure. The results show that the methods of incineration by resistance furnace, incineration in the infrared furnace and the solvent extraction method using centrifuge do not present significant statistical differences, which is not the case with the solvent extraction method using a reflux system. The latter, despite being the one with the lowest variability, is also the most distant from the design asphalt content. However, the four methods studied are within the tolerance allowed by national regulations with respect to the asphalt content established in the blend design. In addition, as some laboratories use the gasoline extraction method as solvent instead of ACS grade trichlorethylene, the extraction test is performed using both solvents to determine whether the result with the alternative solvent is reliable. The results obtained discard it as solvent, as it does not produce statistically comparable results with the method when using trichlorethylene.

In recent years, different test methods and procedures have been developed to evaluate the rheological properties of asphalt materials, some of which have been incorporated in design methodologies and standards in Mexico. However, the correct determination of mechanical properties of asphalt mix involves complex evaluations and the need for other areas of knowledge as metrology, instrumentation and data processing, combined with a clear understanding of the mechanical behavior of a viscoelastic material. This is the case for the dynamic modulus test, which aims to evaluate the linear viscoelastic properties of the asphalt mixture by determining two mechanical parameters, the dynamic or complex module (|E*|) and the phase angle (δ). The present article illustrates the evaluation of the viscoelastic properties of an asphalt mixture and the analysis of the data obtained in tests. Indicating some of the general errors in the conduction of the test and to justify the test sequence proposed by the IMT regarding the AASHTO T 342 Standard, which does not alter the identification of the linear viscoelastic properties of the asphalt mixture. 

The methodology that calculates the internal stresses on a penstock shell restrained by a rigid ring girder was developed since the 1930’s, however, its automatization has not been implemented by commercial use software due to its complexity. This projectintends to automate one methodology to calculate the internal stresses on a steel penstock shellrestrained bya ring-girder. A penstock under normal operation condition, this is apipe full of water under pressure, was analyzed. A calculating tool was produced using EXCEL 2016 and Mathcad 10, for calculating the internal stresseson the penstock’s ring girder cross sections. The tool doesn’t consider the earthquake loading conditions.

The University of Cordoba in Colombia has been declared as a beneficiary of collective reparation, a unique sui generis case in the world. The plan contemplates 48 measures, among them providing the alma mater with a new university statute to replace the one that the United Self-Defense Forces of Colombia (AUC) implemented between the 1990s and the beginning of 2000, by what was called "the bloody and merciless occupation" in which sixteen members of this institution were assassinated, and another group of at least six professors had to go into exile. In the department of Cordoba, two phenomena of opposite sign have been mixed; they facilitated genocidal practices. On the one hand, the political clientelism that traps an electorate in extreme poverty captivated a cacique who concentrated a territorial power. On the other hand, a group that acted under the following triad: landowners, livestock and drug trafficking.  Thus, one of the most impressive concentrations of land in the contemporary history of the country was consolidated. At the end of the last decade, newspapers headlined that being an educator in Cordoba was "the most dangerous profession.” This paper is part of a wider investigation that gives an account of the strategies of paramilitary groups to take over State universities as a war maneuver, using academic control of unions and student movements. Methodologically, we proceed through an analysis of prescriptive, testimonial, journalistic (such as investigations, reports, opinion columns), and academic (research articles, books, reports of undergraduate and graduate studies) documents, as well as in-depth interviews.

The human rights of persons deprived of their liberty is a doctrinal and normative analysisin contrast to the Ecuadorian penitentiary reality. This reflection visualizes the contradictionbetween the claims of guarantee and respect of the minimum rights of the people depriveof liberty and the reality that is lived in the penitentiary centers of Ecuador, according to thestatistical report of 2017, where a high rate of overcrowding is observed, whose consequenceis the violation of the fundamental rights that assist the prison population. There is a speciallegal relationship between the State and the prison population that turns that State into aguarantor of the minimum fundamental rights that these people have that is in a situation ofdouble vulnerability. The need to establish minimum rights for the treatment of persons deprivedof their liberty is based on human dignity, an attribute that is not lost with the limitation offreedom and hence explains the eagerness of the international community to urge governmentsto that protect and guarantee through the legal norm, the fundamental rights that tend topropitiate basic conditions that assure a dignified quality of life in prison. In conclusion, thelegal basis exists for the protection of the minimum rights of persons deprived of liberty, butthey have remained mere declaratory acts that require the will of the government embodiedin public policies that allow the efficiency and effectiveness of the norm.

On May 26, 2017, the African Court on Human and Peoples' Rights (CAfDHP[1]) delivered its judgment in case 006/2012 (the African Commission on Human and Peoples' Rights (ACHPR) against the Republic of Kenya) declaring the massive and serious violation of rights, recognized in the 1981 African Charter on Human and Peoples' Rights, by the Republic of Kenya in favor of the Ogiek community. This decision comes after eight years of struggle. Previously, the system for the protection of the rights of indigenous communities in the African continent had been strengthened by the recommendation of November 25, 2009, of the African Commission on Human and Peoples' Rights in Case 276/03 (Center for Minority Rights Development (Kenya) and Minority Rights Group on behalf of the Endorois Welfare Council/Kenya) where an important doctrine is established about the fundamental rights of these communities, especially with regard to the ownership of ancestral lands and the spiritual meaning of them. Now, in the case of the Ogiek, the court is pronouncing, for the first time, on the violation of the rights contained in the African Charter, with respect to these indigenous communities, in a case whose plaintiff is precisely the African Commission on behalf of this group. This paper highlights some statements made by the Court, both with respect to the consideration of minorities and indigenous communities in general, and with respect to the scope or meaning of their ownership (in reinforcing their rights) and of the territorial integrity of the state in particular.      

The native peoples have recognized, in the legal system of the Argentine Republic, their property rights over the territories they traditionally occupy. Despite this, there is a profound difference between the regulations and the effective enjoyment and exercise of their rights. The objective of this work is to bring to light the following aspects: the current situation of the native peoples in Argentine Republic; the relationship between the State, the private sector and the indigenous communities; the intervention of the State in the face of complaints of irresponsible management of forest resources and the problems raised with regard to the transformation suffered by the corresponding native forests in order to raise awareness of an issue that has caused irreparable losses of natural, cultural and historical assets of the indigenous peoples. In this context, it is a fact that, for the indigenous communities that inhabit the native forests, the technological changes of the industrial society and the incursions of the actors of the market economy require a continuous adjustment in order to survive. The limited capacity to adapt to the demands of the non-indigenous society makes the changes affect the native communities in a special way. That is why these groups are at a crossroad that has worsened rapidly by the dramatic changes of their environment in recent years: the loss of biological diversity erodes their material base for survival, and the loss of cultural traditions weakens their base of values and social structures.

Ana Castro∗   Yo vi morir una casa, y otra casa y otra casa, y allí estaba mi casa. Yo vi morir autos, calles, barrios, luces. Vi morir la panadería, el kiosco y la escuela. Yo vi morir en el fuego los muebles, los colchones y la ropa. Vi morir mi perro que flotó durante días en el comedor. Yo vi morir dibujos,  documentos, títulos, cuadros, libros.   Yo vi morir los juguetes de mis hermanos, las paredes dibujadas por ellos, vi morir cumpleaños. Yo vi morir la espera, los recuerdos y las únicas fotos de mi infancia. Yo vi morir la noche en los sonidos de las balas y los helicópteros. Vi morir la esperanza en los que vivieron meses sobre los techos.   Yo vi morir cubiertos, manteles, lavarropas, televisores, radios, heladeras, cocinas, espejos, sillas, mesas, sillones, almohadas, útiles, mochilas; en cada pila de basura que habitaron las calles.   Yo vi morir el pasado, la infancia de los pibes, las muertes no anunciadas. Vi morir nombres y apellidos, árboles y flores. Vi morir filas de gente buscando gente, de colchones apilados, de paquetes de velas y linternas. La luz de esos días sobrevive en imágenes. La luz de una foto ilumina la memoria y vibra. Las muertes serán siempre eso; oscuridad y luz   ¿Y yo?:              Yo no me quiero morir.