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

Reverse Cuthill McKee (RCM) reordering can be applied to either edges or elements of unstructured meshes (triangular/tetrahedral) , in accordance to the respective finite element formulation,  to reduce the bandwidth of stiffness matrices . Grid generators are mainly designed for nodal based finite elements. Their output is a list of nodes (2d or 3d) and an array describing element connectivity, be it triangles or tetrahedra. However,  for edge-defined finite element formulations a numbering of the edges is required. Observations are reported for Triangle/Tetgen Delaunay grid generators and for the sparse structure of the assembled matrices in both edge- and element-defined formulations. The RCM is a renumbering algorithm traditionally applied to the nodal graph of the mesh. Thus, in order to apply this renumbering to either the edges or the elements of the respective finite element formulation,  graphs of the mesh were generated. Significant bandwidth reduction was obtained. This translates to reduction in the execution effort of the sparse-matrix-times-vector product. Compressed Sparse Row format was adopted and the matrix-times-vector product was implemented in an OpenMp parallel routine.

The Federal government, through the General Direction of Tropical Zones of the Secretariat of Agriculture, Livestock, Rural Development, Fishing, and Food (SAGARPA), has been fostering the opening of 20,000 ha for the cultivation of robusta coffee in the south-southeast states. As part of this initiative, the present study is done to determine in which areas of Tabasco state this type of coffee could successfully be established, and what the impacts of climate change in the middle of the XXI century would be with regard to its adaptation and yields. Thus, the objective of the present study was to determine the best areas, from the climate and soil point of view, for the cultivation of robusta coffee (Coffea canephora P.) in Tabasco state, and their possible vulnerability to climate change in the middle of the current century.Method: This was done using the Agro-Ecological Zones methodology (AEZ) proposed by the Food and Agriculture Organization of the United Nations (FAO) for the current conditions for the (RCP8.5) climate change scenario expected for middle of the XXI century. Also, the potential yields were estimated for three levels of input (low, medium, and high) in the areas that were very apt for both climatic conditions, using the (AEZ) methodology proposed by FAO (1981), updated by Fischer et al.(2012).Results: The results indicate that in the case of a mean daily increase of 1.6 ºC by the year 2050, under the worst-case scenario (RCP8.5), the very apt area for robusta coffee cultivation in Tabasco state is not modified. On the other hand, the mean potential yields would decrease by 41% by the year 2050, due to the effect of the increase of daytime temperatures on the maximum photosynthetic rate.Discussion: In Tabasco state, there are currently 154,755.14 ha that are edapho-climatically very apt for the establishment of robusta coffee. Under the A2 climate change scenario (RCP8.5), a increase in daily temperature of 1.6 ºC is expected, which would not affect the edapho-climatic aptitude of robusta coffee. The mean potential yields vary in function of the amount of input for the age and planting density specified.

The objective of this research was to measure the degree of tourism sustainability and the contribution to local well-being that Cabo Pulmo, Baja California Sur (BCS), Mexico has. This coastal community is subject to environmental protection due to the presence of reefs and the enormous diversity that counts, characteristics that are used for recreational purposes.Although studies on tourism in small communities near the coast are scarce at a national level, it is a fact that the measurement of indicators is a very useful tool to know to what degree or not the strategies are complied with raised.The research used a procedure based on three methodologies: those planned by the International Union for the Conservation of Nature (IUCN), the Association of Caribbean States (ACS) and the World Tourism Organization (UNWTO); the latter is applied by the Ministry of Tourism (SECTUR) in Mexico. To improve the methodology and generate information on new indicators, mixed techniques were applied. Subsequently, the scenarios were formulated and delimited using the Delphi Method.The results of 46 indicators (23 for the social component and 23 for the environment) revealed that the average Local Sustainability Index (ISL) is 0.70. When adjusted based on four weighting criteria proposed by experts, we obtained: ISLae₁ = .73, ISLae₂ = 70, ISLae₃ = .73, ISLae₄ = .84.According to the first three scenarios, Cabo Pulmo, BCS, is located at the "Good" level of sustainability and, exceptionally, in a "High" or "Excellent" range within the last scenario.The main findings indicated that Cabo Pulmo has a certain degree of social backwardness. However, this situation is not unique to the locality studied; rather, it is usually recurrent in small communities or areas near huge poles of tourism development.When comparing the results with other studies, it was found that the site presents the same level of sustainability as other entities in Mexico, such as BCS. Also, it is located above nations such as Sri Lanka, Bangladesh, Nepal, Pakistan and Bhutan.Derived from the results, it is recommended: 1) Pay special attention to improve the indicators categorized as critical, for example: health and education services, water quality for domestic use, housing with drainage, roads in good condition and the relationship visitors vs. inhabitants, and 2) Continue to generate information to evaluate the variation in the level of local sustainability, taking as reference different scenarios and incorporating the opinion of ex-experts (advisors, academics, government) and their own inhabitants.

Introduction: The cultivation of alfalfa is the most used legume for feeding cattle worldwide due to its high nutritional value, mainly of protein, the District of Irrigation 05-Delicias is one of the most important producers of this crop in Mexico. The objective of this research was to determine the impacts of the different forms of use of factors of production on the productive efficiency, with the purpose of generating useful information for producers and authorities for decision makingMethod: In this study, 4 predictors, land tenure, property ownership, specialized machinery and technical irrigation were selected in dichotomous form, and a variable response, productive efficiency in alfalfa cultivation was used to determine the best fit of the model, using the method of variables selecting backward step, they were analyzed under the logistic regression model by CATMOD of the SAS 9.4 package using contrasts to determine effects of the variables on significant interactions.Results: Significant differences were found in the three interaction: property-machinery-technical irrigation, as well as individually in the individual variables specialized machinery and technical irrigation. By contrasting were determines the different effects of the variables within the triple interaction, standing out the potential impact of the technical irrigation-machinery combined, when the property is counted with a odds rate of 16, followed by the effect of the machinery when the producers have the property with a odds rate of 13.56 and the effect of technical irrigation, when likewise the producers are owners of their land too with a rate of odds of 8.0.Discussion or Conclusion: The efficiency of alfalfa cultivation from the productive point of view showed that it is significantly impacted by the triple interaction of the variables property-machinery-technical irrigation presenting the maximum effects when it has the property of the farm inside of that triple interaction by the combined effect of technical irrigation-machinery, likewise the technical-irrigated machinery-irrigation interaction shows significance, but its impact is less when the property is not owned.

Zeolite-clinoptilolite is a hydrated aluminosilicate, which belongs to a group of minerals of volcanic origin and possesses interesting agricultural properties. The aim of this study was to determine the effect of zeolite-clinoptilolite on Solanum lycopersicum Mill. seedling growth, when supplied to substrate in pot culture. An assay was set to test and compare the physical properties of three substrates: peat moss (pm), perlite (per) and zeolite (zeo), and their mixtures (pm:per:zeo) at different proportions: T1 or control = 100:0:0; T2 = 70:30:0; T3 = 70:20:10; T4 = 70:10:20 and T5 = 70:0:30 (v/v). Compared to control plants, substrates containing 30% zeolite increased their water holding capacity (260%), total porosity (8.47%), bulk density (212%) and particle density (230%). Related to control plants grown with 100% peat moss, tomato seedlings cultured in a substrate mixture with 30% zeolite significantly improved shoot length (24.2%), leaf area (64.5%), root length (63.2%), shoot dry weight (62.5%), root dry biomass (208.9%), stem diameter (28.5%) and leaves number (92%), however, the chlorophyll index had no significant effects. The overall outcomes indicated that substrates amendment with zeolite could effectively improve tomato plants growth.

Introduction: Multiple factors of workers such as their health influence their work performance. Mobile communication has been intertwined with daily routines and its use has expanded. The objective of this study was to identify the association of perceived performance adjusted to worker health with mobile use.Method: The Work Role Functioning Questionnaire and the Mobile Related Experiences Questionnaire (CERM) were applied to 114 workers in the footwear and services industry. They also recorded their main pathologies, general characteristics, seniority at work, number of hours worked/week and their opinion regarding the use of mobile phones at work. We performed the Pearson test to evaluate the association between variables considering the normal distribution of data. The dependent variable was the work performance perceived and adjusted to the health status of the worker, as independent variables were considered the age, seniority at work and hours worked per week. Comparisons were made according to whether they were professional or non-professional employees. For the comparison of continuous variables between the groups, we performed unpaired Student t test or Mann-Whitney U test according to the data distribution and chi square for comparison of proportions. A p <0.05 value is considered significant.Results: 70 (61.4%) reported that it is necessary to use the mobile phone in the workplace primarily for communication with staff of the work team, information required at work and as a tool to locate formats, suppliers, etc. In the total group of workers, the mobile use conflict factor showed a negative correlation with the output demands (r=-0.243; p= 0.01), mental (r=-0.267; p= 0.005), physical (r=-0.204; p= 0.03) and the total score of work performance (r=-0.219; p= 0.02). The use of communication was negatively correlated with social demands (r=-0.197; p= 0.03). The total CERM score showed negative association with the total score of the work performance (r=-0.197; p= 0.03) and all its factors except physical demands (r=-0.162; p= 0.08). In women, lower BMI, number of hours worked per week, number of children, couple's years and social demands were identified.Conclusion: Excessive use of mobile phones is inversely associated with perceived work performance in footwear and service workers.

The prevailing development model that prioritizes economic growth presents two clear limits to the nature: the recovery cycles of goods and services and the absorption of residues generated by human activities. The metabolism social theorizes about that limitations and, as such, it is useful to analyze the problematic surround of solid waste or residues. This paper resumes this perspective to understand the disposal practices of the greater producers of solid municipal waste in Holbox Island, Q. R., a site of recent ecotourist promotion. Based on a combination of qualitative and quantitative methods which included surveys and semi-structured interviews, here we analyzed the human and material requirements involved in the spatial transformation that tourism industry promotes, its consumptions and disposal practices of solid waste as well as the knowledge and perceptions about them of: hoteliers, restaurateurs, inhabitants, tourists and people worried about the problem of garbage. The results show the high dependence that ecotourism has on the resources and reservoirs of energy, this dependency manifests on the importation of a quantity and type of inputs that complicate their excretion on the island. Few hotels and restaurants -and many fewer inhabitants- look for products that facilitate excretion -the last process of social metabolism- while there are important sectors that are not involved in waste practices, which prevents a better use of garbage -in a space which is complicated by its population dynamics. All of the above questions the ecotourism promoted by the commodification of spaces because the practices observed do not constitute sustainable alternatives in socio-environmental terms and consider almost exclusively the economic factor.

Introduction: The data available regarding the chemical composition and procedures for the extraction of the propolis are currently inconclusive. In this study the chemical groups present in the extracts of a propolis mixture obtained by different methods were identified. Additionally, their content of polyphenols and flavonoids was determined, and antioxidant and antibacterial activity was studied.                       Method: The extracts were obtained by maceration and for the ultrasonic and microwave method. Phenolic and flavonoid compounds, as well as the measurement of antioxidant activity, were quantified by spectrophotometric methods. The antibacterial activity was studied from the inhibitory effect of each extract against Escherichia coli, Salmonella typhi, Staphylococcus aureus and Proteus mirabilis, and by the percentage of activity and the Index of Bacterial Susceptibility (IBS).       Results: The phytochemical screening evidenced the presence of abundant compounds with important biological activity. It was found a significant difference (p < 0.05) in the antioxidant and antimicrobial activity of the extracts of propolis obtained by different methods.           Conclusion: The presence of chemical groups of bioactive compounds and their antioxidant and antibacterial activity justifies the use of these extracts in traditional medicine.

Number of chromosomes is important for evolutionary studies, phylogenetic, genetic and taxonomic improvement. Due the importance of chromosomes, this research was conducted in order to determine polyploidy on blackberries Rubus adenotrichos Schltdl, R. cymosus Rydb, R. humistratus Steud, R. palmeri Rydb, R. pringlei Rydby, R sapidus Schltdl; Tupi, Kiowa, Tupí x R. sapidus and Kiowa x R. sapidus. Chromosome counting was performed on somatic cells by crushing root tips. Chromosomes were observed and counted in metaphase for each one of specie, polyploidy was determined starting from 1x = 7. Morphological characteristics of each one of specie were based on qualitative descriptors of UPOV 2006. Blackberry showed variability in the number of chromosomal games: Rubus adenotrichos (2n = 2x = 14), R. cymosus (2n = 5x = 35), R. humistratus (2n = 2x = 14), R. palmeri (2n = 4x = 28), R. pringlei (2n = 3x = 21), R. sapidus (2n = 3x = 21); Tupi (2n = 2x = 21), Kiowa (2n = 2x = 28), Tupi x R. sapidus (2n = 2x = 21) and Kiowa x R. sapidus (2n = 2x = 28). Each one of the species presented particular characteristics that characterize them, however, it was not posible to determinate the morphological characteristics associate or define the poly-ploidy in the species analyzed.