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

Aunque el objeto central del libro de Michael J. Sandel es un análisis ético sobre la voluntad de ciertos padres por optimizar genéticamente a sus hijos, en él se abordan también presiones educativas y deportivas familiares mucho más habituales.

The road accidents in Costa Rica have taken the lives of more than 1897 people between 2012 and 2016, of whom 86% were men, the vast majority of car or motorcycle drivers. Of the remaining 14% of women who died, more than 75% were passengers in a vehicle, pedestrians or cyclists. These data raise a hypothesis: the road system and mobility in Costa Rica, responds to a series of social, cultural and historical conditions, framed within a patriarchal scheme in which attitudes and roles of masculinity and femininity predominate that favor that men have a greater exposure to risk of a road accident and suffering fatal or serious injuries than women, the result of a road system configured from the symbolism imposed by a misunderstood masculinity. The article aims to be an initial input to generate a wider and broader discussion about the impact of social roles associated with the condition of being a man or woman on road safety.

The use of bases treated with hydraulic binders or asphalt binders has become a common solution in the construction of pavement bases or sub-bases due to the need to achieve high performance, and also because of the increment of the repetitions and magnitudes of loads in transportation. The treatment with additives provides greater resistance and behavior to the pavement layers over time. A granular material was selected with the purpose of evaluating the effectiveness of one of these treatments. This material did not meet the requirements of a road subbase because of its high plasticity. A cationic asphalt emulsion was incorporated to this granular material in order to check the variations that this treatment could experience regarding its resistance in the laboratory. Finally, good results were obtained with this treatment. An increase in resistance to CBR after immersion and conserved resistance were observed. The modifications produced after the treatments, are also shown by comparing a conventional flexible structure and a structure with a stabilized sub-base layer with an emulsion instead of a non-agglomerate traditional subbase, using an empirical-mechanistic procedure of AASTHO Design Guide.

This research shows the results on the flexible pavement performance (rutting and fatigue) using Reclaimed Asphalt Pavement-RAP and Recycled Tire Rubber. The two types of materials are waste that comes from different processes: the first one comes from recycling asphalt pavement and the second from disused tires due to wear and tear of different vehicles. The studies include analysis of the materials in the original condition and a proposal for improving the material, considering the reduced production of greenhouse gases. The product obtained in this project intended to be used in secondary and tertiary roads (rural roads) in Colombia, to improve the connection between agricultural production areas and urban centers in such a way that it contributes to the improvement and development of the competitiveness of these areas.

Traffic congestion is a problem that occurs worldwide, and Cuba is not exempt, even when the existing levels do not reach those reported by countries with high level of motorization. Signalized intersections in urban arteries of Havana are the most congested, which reflects negative impacts such as traffic accidents, delays, queue, and emission of pollutants into the atmosphere. A possible low-cost solution to decrease congestion is to coordinate the group of traffic signals. Therefore, this research aims to assess the efficiency of synchronized channels using parameters as cycle time, green intervals, and bandwidth for a case study using Synchro software. This research does not consider the minimization of delays of the users. The results support the feasibility of using these parameters to evaluate and select the design holding the most effective synchronization.  

Road safety focused on railway crossings has historically been very weak in Costa Rica. This has generated important consequences in the efficiency and losses of time, for both the passenger of the train system, and for the users of the road, due to the blockages and delays generated by the occurrence of crashes in these locations. Additionally, a greater number of crashes also implies a greater occurrence of major injuries, so it is necessary to reduce the number of crashes at railway crossings by applying infrastructure improvements, in addition to other approaches. This research applies Bayesian statistics and spatial statistics simultaneously to improve the predictions in the total number of crashes at each railway crossing and uses this input to classify the crossings according to their excess of crashes. The crossings with greater promise of improvement are identified and therefore their improvements should be prioritized in related budgets. The results show that the crossing in the Mercado de Mayoreo in La Sabana, the crossing of the Río Pirro in Heredia, among others, present conditions to prioritize their investment.

The objective of this study was to estimate the metabolizable energy (ME) of different forage sources used in Costa Rica through the NRC equation (2001) and the equations used in the in vitro gas production methodology at 24 hours of incubation (PG24h). The chemical, bromatological composition and gas production were analyzed at the Animal Nutrition Research Center (CINA). The two equations with the best Pearson correlation coefficients with respect to the NRC (2001) were selected : that of Steingass and Menke (1980) and that of Menke and Steingass (1988). The relationship between the nutritional composition of the feedstuffs and both energy estimation methods was analyzed with Pearson analysis correlation and linear regression. The forages with the highest and lowest metabolizable energy obtained from the NRC methodology (2001) were Ryegrass (2.59 Mcal kg/DM) and Cameroon (1.79 Mcal kg/DM). According to the NRC equation (2001), it was determined that neutral detergent fiber (FDN), acid detergent fiber (FDA) and lignin negatively influence the energy concentration (R2 = -0.56; -0.54; - 0.35; p <0.05, respectively), while crude protein (PC) and ether extract (EE) have a positive correlation. The equation with the highest determination coefficient (R2 = 0.72) considers the variables of PG24h, PC, FDN and lignin. Gas production is not affected by the concentration of PC, ash and EE (p <0.05), but it is negatively affected by the FDN, FDA and lignin, with a Pearson correlation coefficient of -0.44, -0.32 and -0.33 (p <0.05), respectively. The forage with the highest PG24h was sugar cane, followed by Festulolium and Ryegrass, while Cameroon and Cratylia grass obtained lower values. Ryegrass and Cameroon were the forages with the highest and lowest energy, respectively, estimated from the selected gas equation. The fibrous fractions were negatively correlated with the energy determined by the selected gas equation, while the PC and EE present a positive relationship. The gas production technique proved to be effective in estimating the energy content of forage sources, based on a methodology that includes less analysis and therefore results in a lower cost for laboratory analysis.

The main objective of this research was to measure the effectiveness of homeopathic intraruminal bowling, on the somatic cell count (SSC) in dual-purpose cows diagnosed with subclinical and clinical mastitis belonging to farms in the region of Los Lagos, Chile. The present study was carried out in 5 dairy farms, under a non-probabilistic method a total of 30 samples were chosen, 6 from each farm, of which 4 were “case” and 2 “control”, for a total of 20 and 10, respectively for each group. Six cows per farm with higher SSC were chosen, that were clinically healthy and positive for the LDH test, 4 were case group, to which the product was applied on day 0, while the remaining 2 cows were control group (without product application). The tests were performed based on somatic cell count (SSC) (milk control), and milk lactate dehydrogenase (MLD) test, measuring these 2 diagnostic tests at day 0 and after 21 days. The results of this study show close to 88% effectiveness reducing the RCS below 200,000 cells/ml.

Ruminal methanogenesis consists in reactions that synthesize methane from organic molecules and are performed by methanogenic archeas in the rumen. Microbial methanogenesis in ruminant animals has repercussions both in their metabolism and commercial productivity, and in the stability of the environment.One of the most important factors is the rumian diet,its age and the species. Mitigation strategies are oriented to reduce greenhouse gas (GHG) production or to produce mechanisms that captures GHG-forming compounds. They can be classified into three categories: food and dietary manipulation, animal manipulation and microbial manipulation. These influence the alteration of the rumen ecosystem and the rate of methanogenesis. Quantification of methane produced by ruminants leads the eradication of factors that stimulate methanogenesis.

The aim was to determine whether the supplementation of methionine, threonine and tryptophan in the diets of growing-finishing pigs raised under commercial conditions improved their productive performance (feed intake, weight gain, feed conversion rate, carcass quality) and whether this strategy was economically viable. The experiment was performed simultaneously in 2 commercial pig farms, with animals fed during their grower-finisher period (30 – 100 kg) with a diet that met their ideal protein requirement and a diet supplemented with an additional 20% methionine, threonine and tryptophan. There were no effects (P>0.05) of the diet on feed intake, average daily gain or feed conversion rate in any of the grower-finisher stages, or when the whole testing period was analyzed. Furthermore, there were no differences between diets for the lean meat percentage, the value for each kilogram of meat or the value of the whole carcass. The animals that consumed the supplemented diet showed a tendency (P=0.07) to have a higher back fat thickness (13.46 mm) compared to those that were fed the control diet (12.62 mm). Moreover, the animals fed with the supplemented diet also showed a tendency (P=0.08) to have a higher carcass yield (80.10%) compared to the animals that consumed the control diet (79.54%). It can be concluded that methionine, threonine and tryptophan supplementation did not improve the productive performance of pigs raised under commercial conditions and, under the current productive setup, is not economically viable.