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

Urban mobility has undergone significant changes due to the new social distancing requirements in a COVID-19 scenario. The existence of the new tourism product requires, among other issues, that the urban infrastructure services, and especially regarding the pedestrian design of the historical centers, be modified and reorganized. The objective of this research is to redesign the service provided by the pedestrian infrastructure in Cuban tourist destinations, and especially in its historic centers. The methods used are preparation of the service triangle, assignment of responsibilities, calculation of the service cycle, analysis of organizational technical requirements and calculation of the level of service provided. Among the main results are the redesign of the service provided by the pedestrian infrastructure in Cuban historic centers, the characterization of the new service and the calculation of parameters for its management, the evaluation of parameters such as the service cycle, stability, reliability, and level of service provided. After carrying out an analysis of the service cycle, it is determined that the implementation of the service has a duration of 217 days, the stability is in acceptable values to solve its problems in a proliferative way (81,79%), the reliability of the service has been increasing with the application of the procedure. The calculated service level provided is 84,10% below the service level set in step three of the service cycle and is the starting point for the procedure feedback.

The following investigation aims to determine the serviceability and resistant capacity in a flexible pavement in Azángaro-Salinas km 0+000 to km 3+000, in Puno, Peru. From the results it was possible to determine that for the indicated section there is a PSI (Pavement Serviceability Index) of 3,41 according to the Merlin method, meaning that it has a good serviceability classification. Likewise, through the laboratory results, the resistant capacity is established for the subgrade, subbase, and base. After the most critical CBR was found for each of the layers of the pavement structure, and with the thicknesses found in the field, it is possible to carry out a structural design obtaining as a result that the design requirements were met. As conclusion, it was found a good serviceability of each section, since the determined IRI showed an average of 2,15. Likewise, the PSI total average of 3,41 corresponds to a good serviceability of the entire section studied.

The truck factor is one of the main components in computing the load demand for highway pavements. The aim of this study is to analyse the databases on weighing carried out between 2008 and 2017. Therefore, more than 12 million heavy transport vehicles were counted, these vehicles were distributed in Limon and Cartago weighing stations. For each vehicle, the associated truck factor was calculated. Besides, according to the weight of each of its axles, it was determined if the vehicle did not comply with the provisions of the Legal Decree no 31363 of the MOPT. The econometric models are computed from the truck factor variables and non-compliance percentages. These models take the effect from different variables of the type of truck on the truck factor and non-compliance: spatial and temporal, and the type of measurement. The econometric models consider the following variables: year, month, type of vehicle, day, hour, and the type of measurement applied in the analysed stations. One of the results of this research is that there was an increase in the truck factors and non-compliance percentages analysed when going from a manual weighing system to an automated one.

This article shows the use of Saccharum officinarum stillage in stabilizing cohesive soils. These soils in mention are those that present very poor resistance properties, which prevents the soil from working properly as part of a subgrade on a road. The objective of the research was to determine the stabilization of cohesive soils with the incorporation of vinasse from Saccharum officinarum. The type of research is experimental, the technique used is observation and data collection sheet, through which it was possible to obtain values from the tests carried out in the laboratory with natural soil and soil stabilized with Saccharum officinarum vinasse. The results indicate that the soil under study is low plasticity inorganic silts and clays. With the application of s Saccharum officinarum vinasse, it was identified that the density of the soil increases with the different percentages used. Then, when carrying out the mechanical resistance tests of the stabilized soil, it was possible to increase the resistance with respect to that of the natural soil, being 25% of Saccharum officinarum vinasse the one that obtained the highest values. Research concludes that the incorporation of Saccharum officinarum stillage increases the strength properties of a cohesive soil.

The present investigation was based on the innovation and elaboration of a hot asphalt mix (HMA) due to the premature deterioration of flexible pavements, and low capacity to fulfill its useful life. Then, it is recognized the need to ensure a good quality of materials for the asphalt mix and a search for a new material that can give greater durability and avoiding premature deterioration of the pavement. Thus, the incorporation of steel slag for the HMA design was evaluated with the objective to determine the stability and flow of the hot asphalt mixture incorporating steel slags. To achieve this, the Marshall methodology was developed with a percentage of steel slag with respect to the coarse aggregate in 0% - 15% - 25% - 50% - 75%. The results obtained, in terms of quality of the aggregates, complied with the standards of quality. It was concluded that the modified asphalt mixture with 15% steel slag is the best combination, in the same way this percentage complies for light-medium traffic, the remaining combinations (25% - 50% - 75%) only comply for light traffic. It was possible to increase the stability and flow of the incorporated asphalt mixture up to a maximum of 25% for a HMA with respect to the control mixture.

The aim of this study was to evaluate the effect of supplementation with oilseed by-products (OB) on the productive response of crossbred lambs. The study was carried out between March and July 2018 in a sheep production unit located in the municipality of Planeta Rica, San Jorge Subregion of the department of Córdoba, Colombia. Sixteen lambs with an initial weight of 16.5±3,0 kg and 8-10 months of age were randomly assigned into two groups (n=8) of nutritional treatments; T1= basal diet (forage and mineralized salt); and T2= basal diet (forage, mineralized salt, and SO). The animals were evaluated for mean daily weight gain (DWG), final body condition (FBC), final weight (FW), daily nutrient intake (DNI), digestibility (D), body index (BI), and carcass quality; slaughter weight (SW), hot carcass weight (HCW), cold carcass weight (CCW), hot carcass yield (HCY) cold carcass yield (CCY), carcass length (CL), leg perimeter (LP) and compactness index (CI). All variables evaluated in animals and their carcasses were higher (p<0.05) in T2, which acquired a DWG (p= 0.0006), FBC (p=0.001), FW (p=0.03), DNI (p=0.001), D (p=0.004), CI (p=0.0008) increased by 66.3%; 30.3%; 23.3%; 46.8% and 3.4 percentage points (pp), respectively. The T2 carcasses obtained (p<0.05) values of SW, HCW, CCW and CI were higher in 5.9 kg; 3.34 kg; 3.2 kg; 2.44 pp; 3.07 pp; 5.7 cm; 2.5 cm and 0.035 kg/cm2, respectively. The levels of OB supplementation evaluated increased the productivity and carcass quality indicators in crossbred lambs, becoming a blunt feeding option to improve productive performance in hair lambs from the Colombian low tropics.

This research aimed to evaluate the effects of three levels of the substitution of the dry matter consumption of balanced feed by redworm (Eisenia foetida) on zootechnical parameters and the tissue composition in the initial stages of blue tilapia (Oreochromis aureus). The study was carried out between august and october 2020, in the Aquaculture Research Module of the Alfredo Volio Experimental Station of the University of Costa Rica (Cartago, Costa Rica), and lasted 46 days, with a photoperiod of 12h/12h using artificial light control. A system was established with 12 fish tanks, having a total of eight hormonally reversed tilapia, weighing initially 3,25 g ± 0,35 g. The red worm was obtained from the vermicompost module of the same Experimental Station, where it was dehydrated by heat convection for its experimental use. A completely randomized design of one factor and three repetitions per level with four treatments was performed: the Control Treatment (T0) and three balanced feed substitution levels for dehydrated worms in percentages of 25 % (T1), 50 % (T2), and 75 % (T3) of the dry matter. The fish were anesthetized every two weeks to evaluate the parameters of total weight gain (GPT), increase in standard length (iSL), condition factor (K), specific growth rate (TCE), feed conversion rate (FCR), protein efficiency ratio (PER) and cumulative mortality. At the end of the experiment, the biochemical composition of the fish was also evaluated; the chemical composition did not show significant differences by treatment and was not affected by the substitution of dehydrated earthworms. Significant differences were obtained between the T3 and T0 treatments for GPT, iSL,TCE, FCR and PER at the end of the trial; determining that up to 50 % of worm can be provided in the daily ration for the fingerlings without affecting those parameters. However, more research is needed on relevant aspects of the use of earthworms as a nutritional input, such as digestibility, antinutritional properties, and greater detail in nutritional profiling.

The research work evaluated seven forage species at different regrowth ages, at two times of the year in three different agroclimatic zones of Costa Rica. A treatment design was used with a 7x2x4 factorial arrangement (forage species, time of year and regrowth days) with three repetitions, with 168 experimental units. The biomass (kg MS/ha), concentration of dry matter (%DM), crude protein (%PC), ash (%CE) and ether extract (%EE) were evaluated for each sample. In the higher altitude zone, the grasses of Kikuyuocloa clandestinum (Kikuyo), Lolium perenne (Ryegrass perenne) were evaluated. The ryegrass grass presented the highest content of PC (18.9%) in the dry season at 28 days regrowth (triple interaction, p<0.01), also obtaining the highest EC content (17.0%) in the dry season at 42 days of regrowth (triple interaction, p<0.01). In the intermediate zone, the grass Cynodon nlemfuensis (African star) showed the highest content of DM (36.6%) in the dry season at 28 days of regrowth (doble interaction, p<0.05), and the highest biomass production (5240 kg MS/ha) at 56 days of the rainy season (doble interaction, p<0.05). In the low zone the pastures evaluated were: Brachiaria brizantha cv. Diamantes, Panicum maximum cv. Mombaza, Ischaemum indicum cv. Ratana and Brachiaria brizantha cv. Toledo. The Mombaza grass presents the highest biomass production (11507 kg DM/ha) in the dry season 56 days after regrowth (triple interaction, p<0.05). Finally, Toledo and Ratana pastures showed values of EC of 8.3% and 15.4% in the dry season (double interaction, p<0.05).

The study consisted of evaluating seven species of grasses at different regrowth ages and times of the year (dry season and rainy season), in three different agroclimatic zones of Costa Rica. A 7x2x4 factorial design (forage species, season, and regrowth age) was used with 3 repetitions for 168 experimental units. The concentration of neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (LIG), in vitro digestibility of dry matter (IVDDM), and in vitro digestibility of neutral detergent fiber (dNDF) were evaluated. In the high zone, the Kikuyuocloa clandestinum and Lolium perenne grasses were evaluated, where the highest content of LIG (10.5%) was presented in the K. clandestinum grass with 14 days of regrowth in the dry season (triple interaction, p<0.01). The L. perennial grass showed the highest IVDDM content (81.1%) at 28 days of regrowth in the dry season (triple interaction, p<0.01). In the intermediate zone, the Cynodon nlemfuensis grass was evaluated, where the highest concentration of ADF (37.2%) appeared at 28 days of regrowth in the dry season (double interaction, p<0.01), and the highest content of dNDF (72.9%) at 14 days of regrowth during the rainy season (double interaction, p<0.01). The following pastures were evaluated in the lower zone: Brachiaria brizantha cv. diamonds, Panicum maximum cv. mombaza, Ischaemum indicum, and Brachiaria brizantha cv. toledo, where the highest content of LIG (9.7%) was found in I. indicum grass after 14 days of regrowth during the dry season (triple interaction, p <0.01), the highest DIVMS (70.5%) occurred at 14 and 28 days of regrowth in the rainy season in diamond grass (triple interaction, p<0.01).

The aspects that compose animal welfare are complex and multidimensional. The first week of life is critical in the development of chickens; the welfare problems in this period are the result of accumulation of factors that compromise the individual animal and the flock. The objective of this work was to identify environmental, housing, health, and behavioral indicators to know their relationship with chickens´ welfare on commercial farms during the first week of life. The effect of multiple indicators on welfare variables was studied: mortality, selection, body temperature, lameness, scratches, and pododermatitis. Principal component analysis (PC) was performed to reduce the complexity of the factors studied. Correlation and regression analyses were performed with PC as regressive variables to understand the relationships between PC and animal welfare variables. 15 houses from 15 commercial farms, located in the north and central zone of Costa Rica were evaluated from January to July 2019. The analysis reduced the complexity of the indicators to seven variables: production, disease, skin and leg integrity, density, resources, environment, and behavior. The PC that best described variability in welfare were behavior, skin and leg integrity, density, disease, and resources. The models that best explained the relationships were those including PC production and health, housing and behavior, health and housing, density and behavior, disease, and housing. The wet litter showed significant differences (p<0.05) in the welfare variables; however, most of the evaluated farms showed good skin and leg integrity scores. The principal components approach allowed the identification of the main effects that affected broiler´s welfare on the farms during the first week of age: heating, litter quality, disease, resource availability, environment, and motivational behaviors. It also allowed farm classification according to their degree of association with health variables.