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

The objective of the study was to establish guidelines for the viability test of seeds by tetrazolium in Cenchrus ciliaris using the Panicum protocols (ISTA, 2012). We worked with fascicles (dispersion unit) of Cenchrus ciliaris of the Texas cultivar from which caryopses were extracted to perform the tests. The appropriate method for cutting caryopses and the staining times were determined and two concentrations of tetrazolium solution were tested. In addition, after adjusting the conditions, evaluation protocols were developed. The adequate conditions to perform the viability test are 18 h of seed wetting between papers at a temperature of 20 °C, incomplete longitudinal cut through the embryo, tetrazolium concentration at 0.5 or 1 % and 10 hours of staining at 30 °C. The staining maps allow differentiating accurately the viability of the caryopses.

Pesticide spraying is the most widespread form of pest control. Spraying is a complex process, from the agronomic and environmental point of view. A field trial was carried out, to evaluate the effect of three agrochemical application techniques. In all of them, an air-induced flat fan was used, with different application rates, sprayer speeds and noozle spacing. Three techniques were defined: T1 (57 l ha-1, 18 km h-1 and 0,35 m), T2 (28,7 l ha-1, 18 km h-1 and 0,70 m) and T3 (57 l ha-1, 9 km h-1 and 0,70 m. To assess the techniques, water-sensitive cards were placed on the ground in vertical columns, to measure the quality of application, sedimenting spray drift and cumulative airborne spray drift. The three techniques were similar in application quality but T1 reached a greater coverage. Regarding the airborne drift factor, T2 presented significant differences with respect to the other two techniques, which leads to the conclusion that higher speeds, larger noozle space and lower application rates increase airborne drift. There were no differences in sedimenting drift. Operational variables affect environmental risks regardless of the drop size produced.  

In Argentina there are few studies referring to Lepidoptera harmful to the cultivation of Chenopodium quinoa. The objective of this work was to identify species of the mentioned order in quinoa in high areas of Jujuy. With this aim, larvae of these insects were extracted from panicles of Chalguamayoc (Yavi, Jujuy) in February and November of 2011. They were kept in breeding cages and fed with panicles of the crop until the emergence of adults. In addition, the specimens of Lepidoptera associated with quinoa in Jujuy, which are deposited in the Entomological Collection of Instituto de Biología de la Altura (INBIAL), were reviewed.The identification was carried out through microscopic preparations of female and male genitalia and the observation of wing coloration patterns. Three species were identified: Eurysacca melanocampta (Gelechiidae, Gnorimoschemini), Copitarsia incommoda and Copitarsia corruda (Noctuidae, Cuculliinae). This contribution represents the first reference to E. melanocampta and C. corruda in Argentina, the expansion of the distribution of C. incommoda in the country, and the first record of C. incommoda and C. corruda on Chenopodium quinoa as a host plant.

The sub-basins of the Maravilla-Chiz and Quebrada Honda Rivers have an approximate area of 46.8 km2 and are located in the eastern part of the Costa Rican metropolitan area, where agricultural and livestock productions are the main economic activity. The sub-basins supply the populations nearby with groundwater sources. The objective of the paper was to determine the possible groundwater contamination by assessing the state of the protection areas of springs used for public water supply. For such purposes, potential point, line, and diffuse sources of contamination were considered and classified according to the POSH (Pollutant Origin and its Surcharge Hydraulically) method. The protected area corresponded to a 200 m radius around the headwaters (Costa Rican Law 276). Results identified that 7% of the area showed diffuse sources of high potential generating pollutant load, due to the large quantities of pesticides used in greens and vegetables, while 55% presented a moderate potential in plots of sugarcane, coffee, and urban areas with no sanitary sewer. Half of the point sources found were classified as a high potential and 46% as moderate. Of the 252 line-kilometers corresponding to rivers, road network, and pipeline, 89% was classified as moderate potential, 10% as high, and 1% as reduced. Finally, the invasion of line and diffuse sources in the spring protection areas was confirmed; therefore, the local government is recommended to start a legal procedure to address the problem.

The objective of this paper is to conduct a theoretical study on the meaning of mathematical proof, taking into consideration three main elements: concept, types, and functions. This is a qualitative and descriptive research. The method used to collect and analyze information is the conceptual analysis. Four sources of information were considered: dictionaries, textbooks, previous research, and the mathematics curriculum of the Ministry of Public Education of Costa Rica. The technique for collecting the information was the bibliographic review. It was determined that proof has different meanings depending on the context; that the types of mathematical proof can be classified into two categories, direct and indirect; and that there are different functions attributed to mathematical proof which are relevant depending on the field in which they are considered. Consequently, the three previous elements should be part of math teachers’ specialized knowledge to promote math proof in secondary education.

The objective of this investigation is to explore the relationship between slow and fast magnetic Rossby waves and certain observations of long-term solar activity (months, years, decades, …). This paper seeks to determine if the periods of these waves correspond to the values recorded for cycles such as the Rieger cycle and the Haly cycle, or otherwise to quasi-periodic outbursts and of flares and Coronal Mass Ejections. The study begins with a literature review and a summary of the results of a Ph.D. dissertation that completely solves the mathematical model analyzed; using the equations derived from this previous work, the periods of the waves are calculated and then compared to observations. The results of this comparison suggest that certain types of solar activity may be due to Rossby magnetic waves originating within the Sun, specifically in the tachocline. The slow magnetic Rossby waves are associated with long-term and very long-term cycles, while the fast magnetic Rossby waves are a plausible cause for cycles with periods of months or a few years. The study of magnetic Rossby waves and their properties will doubtlessly provide new insights into the origin and properties of the solar magnetic field.

This article is part of a more extensive project aimed at analyzing stochastics teaching and learning processes in special education. The teaching of this educational level is presented here using a qualitative approach. From a theoretical perspective, three guiding axes were considered: the epistemological, cognitive and social axes. The larger study was divided into three phases.  This paper will be focused partly on the second phase, particularly on the introduction of the probability distribution for four teachers in a guided study scenario, using teaching scripts and logbooks as instruments.  Data was recorded in video and in writing. In addition, operational body and teaching analysis unit were applied. Results include the teachers’ gradual acquisition of the ideas of sample space, probability measure, random variable (relative frequencies), distribution, and symmetry.

This article describes the curricula offered by state and private universities in Costa Rica to obtain a teaching degree in cycles I and II of elementary education. The study is qualitative and descriptive. Curricula from different universities were reviewed, and coordinators of related programs and math professors from those universities were interviewed. The analysis revealed a wide variety of study programs to train elementary school teachers with no general guidelines and little control. Therefore, there are no regulations in Costa Rica for these programs’ purposes, duration, content or teacher profile, which could affect math education in elementary schools since teachers come from programs with different emphasis

The use of effluents constitutes a viable alternative in agricultural production, transforming a waste into a useful resource, providing water and nutrients to crops. The objective of the study was to evaluate the use of treated urban effluents in the production of broccoli (Brassica oleracea var italica). The treatments resulted from the combination of three cultivars: ‘Matsuri’ (C1), ‘Green Pia’ (C2) and ‘Almanor’ (C3), and two irrigation sources: treated urban effluents (EUT) and aquifer water (AC), supplied by subsurface drip irrigation during two seasons (E1 and E2). The experimental design was in divided plots. At harvest, partition of assimilates in leaves, stems and head was evaluated as well as head diameter, fresh yield and sanitary quality of the product through microbiological and parasitological analyses. The results showed significant differences (p? 0.05 Fisher) in yield for cultivars C2 and C3 (E1) irrigated with EUT. The head diameter presented differences for C2, C3 (E1) and C3 (E2). In E1 the environmental conditions were more favorable, influencing the yield of the cultivars. The sanitary quality tests of the heads determined that they were adequate for fresh consumption, demonstrating that this technology could be applied for broccoli production.

This work is part of the research carried out in the Heritage Group of the FAUD-UNMDP, with respect to the Preservation of the Architectural Heritage of Welfare and the Doctorate of Social Work. Two architectural works constructed by the Society of Charity in Argentina, located in the city of Mar del Plata, such as the “Solarium” (today demolished) and the current “Saturnino Unzué Institute” (formerly the the city, declared a National Monument) that were built at the beginning of the 20th century. These buildings are analyzed from the Foucaultian perspective of power, as “disciplinary devices” implanted within the city, with respect to the historical process of construction of the modern State.On the other hand, it is noteworthy that these works, beyond their architectural values, have a great “testimonial value” as historical documents in themselves, since they are spatial enclaves in which the passage of the different paradigms of assistance converge social throughout its history. For this study different documentary and bibliographical sources were taken, among them albums of the same Society of Beneficence, planimetry and historical photos, that allow to see these problems expressed in the history of its walls, its documents and regulations.