Improving the revision stage of a CBR system with belief revision techniques.

This paper presents a method for automating the revise phase of case-based reasoning systems. The revision is carried out using a rule -based system, which adapts its rules or knowledge base as the working environment, to which the system is applied, evolves in time. This actualisation is carried out by a belief revision technique. An example has been introduced to illustrate the working mode of the revision techniqu

Impact of the USMCA on corn (Zea mays L.) trade dynamics and food security in Mexico

Objective: To determine the impact of corn imports on food security in Mexico by describing the trade dynamics generated by the United States-Mexico-Canada Agreement (USMCA) to highlight the positive effects of foreign trade and free trade policies. Design/Methodology/Approach: The research is based on a quantitative analysis of statistical data on corn involving 27 periods, coinciding with the entry into force of the North American Free Trade Agreement (NAFTA). We used a gravity model with two simultaneously estimated equations—very effective in describing the economies’ trade dynamics. Results: The estimate of the simultaneous equation model identified the United States as the country of greatest significance regarding corn trade with Mexico—an important consideration being that corn trade has a major influence on food security. Study limitations/implications: The most relevant limitation was the lack of a unique source for data documentation. Findings/Conclusions: Mexico’s government policy aims to guarantee food supply. Yet, in 2020, imports supplied 36% of the national corn consumption. Corn imported from the United States is of the yellow variety; the tariff liberalization of this product as per USMCA and the geographical proximity to Mexico contribute to the imported volumes of yellow corn. As per the measurements provided by the Food and Agriculture Organization of the United Nations (FAO), the physical availability of food—in this case, corn—and the economic and physical access to food are met in Mexico. Nevertheless, food security has not been achieved, since 70% of the supply for consumption should come from national productio

Analysis of Copra and Coconut Oil Markets in Mexico

Abstract Objective: To assess the economic impact of the implementation of different production systems (real, traditional, intensive and organic) on the profits of copra producing states and major coconut oil companies. Design/methodology/approach: A linear programming model was formulated which considered the main costs and production revenues, and the transport costs of the copra and coconut oil market, in order to maximize the profit of copra producers and the oil industry simultaneously. Results: The states that were most suitable in the distribution of copra were Guerrero and Tabasco, which proved to be the main suppliers in all the production systems evaluated; within production systems, the intensive system presented a higher level of profit in the scenarios raised. Limitations/implications: The model considered the sale of copra as the sole income of producers, leaving aside the marketing of other products and economic transfers, thus underestimating their total profit. Future research is required to help collecting data on alternative sources of income from producers.  Findings/conclusions: Increasing copra production without taking into account installed capacity in the industry results in the creation of a copra surplus in most producing states, which would result in a fall in the prices of this producto, therefore, reducing the profit of most states.Objective: To assess the economic impact of the implementation of differentproduction systems (real, traditional, intensive and organic) on the profits of copra-producing states and major coconut oil companies.Design/Methodology/Approach: A linear programming model was formulatedwhich considered the main costs and production revenues, and the transport costs ofthe copra and coconut oil market, in order to maximize the profit of copra producersand the oil industry simultaneously.Results: The states that were most suitable in the distribution of copra wereGuerrero and Tabasco, which proved to be the main suppliers of all the productionsystems evaluated; within production systems, the intensive system presented ahigher level of profit in the scenarios raised.Study Limitations/Implications: The model considered the sale of copra as thesole income of producers, leaving aside the marketing of other products and economic transfers, thus underestimating their total profit. Future research isrequired to help collect data on alternative sources of income for producers.Findings/Conclusions: Increasing copra production without taking into account theinstalled capacity in the industry results in the creation of a copra surplus in mostproducing states, which would result in a fall in the prices of this product, thereforereducing the profit of most states

Physiological concentrations of zinc have dual effects on P2X myenteric receptors of guinea pig

"We, hereby, characterize the pharmacological effects of physiological concentrations of Zinc on native myenteric P2X receptors from guinea-pig small intestine and on P2X2 isoforms present in most myenteric neurons. This is the first study describing opposite effects of Zinc on these P2X receptors. It was not possible to determine whether both effects were concentration dependent, yet the inhibitory effect was mediated by competitive antagonism and was concentration dependent. The potentiating effect appears to be mediated by allosteric changes induced by Zinc on P2X myenteric channels, which is more frequently observed in myenteric neurons with low zinc concentrations. In P2X2-1 and P2X2-2 variants, the inhibitory effect is more common than in P2X myenteric channels. However, in the variants, the potentiatory effect is of equal magnitude as the inhibitory effect. Inhibitory and potentiatory effects are likely mediated by different binding sites that appear to be present on both P2X2 variants. In conclusion, in myenteric native P2X receptors, Zinc has quantitatively different pharmacological effects compared to those observed on homomeric channels: P2X2-1 and P2X2-2. Potentiatory and inhibitory Zinc effects upon these receptors are mediated by two different binding sites. All our data suggest that myenteric P2X receptors have a more complex pharmacology than those of the recombinant P2X2 receptors, which is likely related to other subunits known to be expressed in myenteric neurons. Because these dual effects occur at Zinc physiological concentrations, we suggest that they could be involved in physiological and pathological processes.

Indigencia, un abordaje multidisciplinar y una propuesta de intervención en la Zona Centro de Guadalajara

El trabajo se propone hacer un abordaje multidisciplinario de tipo exploratorio en el que se estudien aspectos legales, económicos, sociales, asistenciales, culturales y de difusión del fenómeno de la indigencia y de los actores que la viven y conviven con ella pensando en que este tema podría dar pie a abordajes más profundos desde la academia y otras instancias

Characterization of agricultural practices in the community Mulato Viejo in Oaxaca

ABSTRACT Objective: Document the standard of living of the "Mulato Viejo" community, their culture and agricultural practices in light of current development policies. Design/methodology/approach: The study was carried out during the year of 2019, applying surveys and interviews using key informants with experience in community positions. Results: The results showed that families practice some traditional farming techniques with family labor. A delay was also observed in the incorporation of women (5.5%) and in the generational rotation of producers, 84% are over 40 years old and of these 69% only have primary education, so they do not know the fundamentals of agricultural practices used, this limits the use of machinery to reduce workload, production costs or innovate Limitations on study/implications: The main limitation was the sample size and the repeatability of the study, a single community was analyzed. It is proposed to extend to other communities with similar characteristics Findings/conclusions: Semi-traditional agriculture has preserved the local maize races. However, it is necessary for the community to incorporate dynamics that diversify agricultural activities, crops, establish intra-community cooperation and trade networks, so that agricultural activities are a profitable economic option for the new generations, who would have a greater capacity to acquire the foundations of a sustainable agriculture that improves its yield but, with the challenge of keeping traditional agricultural practices intact Keywords: Mulato Viejo, rural nucleus, solidarity networks.Objective: To describe the standard of living in the "Mulato Viejo" community; culture and their agricultural practices facing the current governmental development policies. Design/methodology/approach: The study was conducted during 2019, applying surveys and interviews to key informants with experience in community-elected positions. Results: The results showed that families practice some traditional farming techniques based on family labor. There was also a lag in the incorporation of women (5.5%), and in the generational renewal of producers. For example, 84% are older than 40 years-old and out of those, only 69% completed elementary education. Thus, they do not know the rationality fundamentals of the agricultural practices they use. This limits the use of machinery to reduce the workload and the production costs, or to innovate. Study limitations/implications: The main limitations were the sample size and the replicability of the study; a single community was analyzed. It is proposed then to expand the study to other communities with similar characteristics. Findings/conclusions: Semi-traditional agriculture has preserved local landraces of maize. Yet, it is necessary for the community to incorporate dynamics that may diversify agricultural activities, crops; and allow establishing networks of cooperation and intra-community trade. So that agricultural activities may become an economic option profitable to further generations, who would have a greater capacity to acquire the bases for a sustainable agriculture. With the goal to improve yield but, with the challenge of keeping the traditional agricultural practices intact

Evolutionary and phenotypic characterization of two spike mutations in European lineage 20E of SARS-CoV-2.

We have detected two mutations in the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at amino acid positions 1163 and 1167 that appeared independently in multiple transmission clusters and different genetic backgrounds. Furthermore, both mutations appeared together in a cluster of 1,627 sequences belonging to clade 20E. This cluster is characterized by 12 additional single nucleotide polymorphisms but no deletions. The available structural information on the S protein in the pre- and postfusion conformations predicts that both mutations confer rigidity, which could potentially decrease viral fitness. Accordingly, we observed reduced infectivity of this spike genotype relative to the ancestral 20E sequence in vitro, and the levels of viral RNA in nasopharyngeal swabs were not significantly higher. Furthermore, the mutations did not impact thermal stability or antibody neutrali- zation by sera from vaccinated individuals but moderately reduce neutralization by convalescent-phase sera from the early stages of the pandemic. Despite multi- ple successful appearances of the two spike mutations during the first year of SARS-CoV-2 evolution, the genotype with both mutations was displaced upon the expansion of the 20I (Alpha) variant. The midterm fate of the genotype investi- gated was consistent with the lack of advantage observed in the clinical and ex- perimental data

Women representation in soil science: gender indicators in the University Program of Interdisciplinary Soil Studies

IntroductionIn the world, 33% of soils are degraded, and 2.9 million people are affected by land degradation, with problems associated with food security, conflicts over natural resources, and migration with different impacts on men or women. To support sustainable soil management, it is necessary to include women’s contributions to soil Sciences; their achievements and academic performance still need to be represented. Women in Science represent 30% worldwide. In Mexico, only 24% of top academic positions are women. For commitment to soil Sciences for Sustainable Development Goals (SDGs), UNAM created the University Program for Interdisciplinary Soil Studies (PUEIS).MethodsThis research evaluates women’s representation through gender indicators in the PUEIS and SNI datasets and discusses their implications for the gender gap in the soil Science community from Mexico. The data was collected with an online semi-structured survey and the gender indicators selected were related to participation, gender gap, sexism, equal opportunities, exclusion, and academic performance.ResultsThe results show that in the PUEIS, 54% of members identify themselves as women and 46% as men. The gender gap shows equality in the total number of members. However, low-rank jobs, such as lecturers and lab technicians are women dominated, and the top-ranked positions as a full professor, associate professor, and research scientist are equal. One result to consider for the PUEIS members is that the younger generation, as is the older generation, is dominated by men. This could indicate a setback in intermediate generations’ progress toward achieving gender equality. In the case of SNI members, there is a gender gap problem; of members with a Ph.D. degree, only 38% are women, and the elite group of scientists with a Ph.D. at the top position is represented only by 24% of females.DiscussionThis work constitutes the first gender exercise for analyzing women’s participation in the soil Sciences in Mexico. From our perspective, it is not about competition in scientific careers between women and men; however, it is essential to recognize that gender inequalities are related to income, professional development, and science funding inequalities, and these disparities impact women more than men

Principales enfermedades del cultivo de tomate (Solanum lycopersicum L.) en condiciones de campo

Tomato is an important crop in producing area of ​​southern Tamaulipas, a limiting factor for its production is diseases, caused by fungi, viruses and bacteria, they can spread in open field conditions, and they develop quickly when the weather is favorable. To carry out effective control it is important to identify the causative agent and differentiate its symptoms, establishing a monitoring program and applying control measures under an integrated disease management scheme, using disease resistant and tolerant varieties, in addition to the use of different insecticides, fungicides and bactericides. However, it is important to integrate cultural practices and management of sowing dates, biological control with entomopathogens and antagonists. This review reports the main diseases of open field tomato cultivation in southern Tamaulipas, Mexico, emphasizing symptomatology, economic importance, morphological characteristics, and disease management.El tomate es un cultivo importante en la zona productora del Sur de Tamaulipas, un factor limitante para su producción son las enfermedades, causadas por hongos, virus y bacterias, pueden propagarse en condiciones de campo abierto, y se desarrollan rápidamente cuando el clima es favorable. Para realizar un control eficaz es importante identificar el agente causal y diferenciar sus síntomas, estableciendo un programa de monitoreo y aplicar las medidas de control bajo un esquema de manejo integrado de enfermedades, usando variedades resistentes a las enfermedades, además del uso de diferentes insecticidas, fungicidas y bactericidas. Sin embargo, es importante integrar prácticas culturales como y manejo de fechas de siembra, control biológico con entomopatógenos y antagonistas. Esta revisión informa las principales enfermedades del cultivo de tomate a campo abierto en el sur de Tamaulipas, México, haciendo énfasis en la sintomatología, importancia económica, características morfológicas y el manejo de la enfermedad

Implementation of activities based on Reading Comprehension As a strategy for strengthening critical reading

La presente investigación aborda a la comprensión lectora como una de las competencias básicas que se deben adquirir a lo largo del periodo escolar, en este sentido, si los estudiantes no son capaces de comprender lo que leen, mucho menos podrán desarrollar una postura frente a lo mismo, por lo que es necesario desarrollar la comprensión lectora para contribuir a un entendimiento global de los textos. Para esto, se realizó un diagnóstico de los niveles de las competencias lectoras de los estudiantes de 3° de la Institución Gilma Royero Solano, basado en resultados arrojados por las Pruebas Saber 2016, para luego de establecer una serie de estrategias enfocadas en la comprensión lectora, en el nivel de lectura crítica y aplicarlas al mismo grupo, con el fin de mejorar sus competencias lectoras y compararlas con los resultados obtenidos en pruebas realizadas por los docentes a partir de las Saber en el 2017.This research addresses reading comprehension as one of the basic skills that must be acquired throughout the school period, in this sense, if students are not able to understand what they read, much less can develop a position in front of what they read. same, so it is necessary to develop reading comprehension to contribute to a global understanding of the texts. For this, a diagnosis of the levels of reading skills of the students of 3rd of the Gilma Royero Solano Institution was made based on the results of the 2016 Saber Tests, after establishing a series of strategies focused on reading comprehension in the level of critical reading and apply them to the same group in order to improve their reading skills, compare them with the results obtained in tests made by teachers from the Saber in 2017