Modellization of the process of natural aging of a polymer material applied for greenhouse covers

[EN] It is presented a procedure to determine the aging of greenhouse cover materials constituted by a polymer material. For this purpose, it is performed a continued monitoring of the photosynthetically active radiation (PAR) and the global radiation during three campaigns. It has been studied in this research samples taken at different zones of the cover, after breakage using mechanical traction. It is deduced a useful life of the polymer of two years, being the average transmitted PAR of 37.44%. However, the absorbed global radiation is determined a value of 36.29%. Furthermore, the elongation to the breakage is above of 500%. This high value is associated to an intense degradation of the polymer material. At the same time, the zone where the sample was taken seems to influence both the strength of mechanical traction and the elongation at the fluence point. The designed tests have been useful to develop a modellization procedure based on the minimum squared method for the adjustment of the data. The proposed model can be used for the design of greenhouse covers and thus allows predict the degree of deterioration of the polymer material at every moment. It is also interesting to keep watch of the need of removing it. The numerical simulations using the finite elements method can represent adequately the mechanical behavior of the cover material. It is been also deduced in this research that the behavior of the covers is at the plastic zone of material.[ES] Se presenta un procedimiento para la determinación del envejecimiento de un material polimérico utilizado como cubierta de invernaderos. Se llevó a cabo un seguimiento continuo de la radiación fotosintéticamente activa (PAR) y de la radiación global durante tres campañas. Igualmente, se tomaron muestras de diferentes zonas de la cubierta, que se han roto a tracción. Se deduce una vida útil del material polimérico de dos años, siendo radiación PAR media trasmitida del 37,44%. Sin embargo, la radiación global absorbida fue de 36,29%. Igualmente, se ha verificado que la elongación a la rotura está por encima del 500%. Este alto valor se debe a que el polímero está muy degradado. También se observó que la zona donde se ha tomado la muestra influye tanto en la resistencia a tracción como en la elongación en el punto de fluencia. Los ensayos han sido de utilidad para desarrollar un procedimiento de modelización basado en el método de mínimos cuadrados para el ajuste de los datos. El modelo propuesto presenta utilidad para el diseño de cubiertas para invernaderos y permite así predecir el grado de deterioro del material polimérico en un instante determinado, alertando también de la necesidad de renovación del mismo. De este modo, las simulaciones numéricas con elementos finitos pueden representar de forma adecuada el comportamiento mecánico de las cubiertas. Se comprobó que el comportamiento de la cubierta está en la zona plástica del materialPeer reviewe

Debate sobre la Ley Federal del Trabajo

Se recuerda con preocupación la forma como la política laboral instrumentada en el sexenio de Carlos Salinas impuso "soluciones" a cada uno de los conflictos obrero patronales, soluciones adoptadas al margen y por sobre la normatividad laboral de esos días. Se abre boca a la discusión sin pensar que los avances tengan alguna significación, ya que muy pronto se llegó a ciertas conclusiones colectivas, de definición y proposición de temáticas tales como la libertad sindical, las condiciones de trabajo y la efectividad de las nuevas normas. Estas propuestas y reflexiones hechas en un contexto en el que la productividad en el trabajo y la capacitación para su realización, son preocupaciones de los trabajadores y sus sindicatos, en que la búsqueda de una salida a la crisis económica que padecemos puede ser encontrada sin mayores sacrificios que los que ya padece la clase trabajadora y en función a un interés nacional y popular

Discrete-Event Simulation for Performance Evaluation and Improvement of Gynecology Outpatient Departments: A Case Study in the Public Sector

Gynecology outpatient units are in charge of treating different gynecological diseases such as tumorous, cancer, urinary incontinence, gynecological pain, and abnormal discharge. On-time attention is thus needed to avoid severe complications, patient dissatisfaction, and elevated healthcare costs. There is then an urgent need for assessing whether the gynecology outpatient departments are cost-effective and what interventions are required for improving clinical outcomes. Despite this context, the studies directly concentrating on diagnosis and improvement of these departments are widely limited. To address these concerns, this paper aims to provide a Discrete-event Simulation (DES) modelling framework to help healthcare managers gain a better understanding of the gynecology outpatient services and evaluate improvement strategies. First, the patient journey through the gynecology outpatient service is mapped. To correctly represent the system uncertainty, collected data is then processed through input analysis. Third, the data is used to model and simulate the real gynecology outpatient unit. This model is later validated to determine whether it is statistically equivalent to the real system. After this, using performance metrics derived from the simulation model, the gynecology outpatient department is analyzed to identify potential improvements. We finally pretest potential interventions to define their viability during implementation. A case study of a mixed-patient type environment in a public gynecology outpatient unit is presented to verify the applicability of the proposed methodology. The results evidenced that appointment lead times could be efficiently reduced using this approach. © 2019, Springer Nature Switzerland AG

Transgenes in Mexican maize: molecular evidence and methodological considerations for GMO detection in landrace populations

A possible consequence of planting genetically modified organisms (GMOs) in centres of crop origin is unintended gene flow into traditional landraces. In 2001, a study reported the presence of the transgenic 35S promoter in maize landraces sampled in 2000 from the Sierra Juarez of Oaxaca, Mexico. Analysis of a large sample taken from the same region in 2003 and 2004 could not confirm the existence of transgenes, thereby casting doubt on the earlier results. These two studies were based on different sampling and analytical procedures and are thus hard to compare. Here, we present new molecular data for this region that confirm the presence of transgenes in three of 23 localities sampled in 2001. Transgene sequences were not detected in samples taken in 2002 from nine localities, while directed samples taken in 2004 from two of the positive 2001 localities were again found to contain transgenic sequences. These findings suggest the persistence or re-introduction of transgenes up until 2004 in this area. We address variability in recombinant sequence detection by analyzing the consistency of current molecular assays. We also present theoretical results on the limitations of estimating the probability of transgene detection in samples taken from landraces. The inclusion of a limited number of female gametes and, more importantly, aggregated transgene distributions may significantly lower detection probabilities. Our analytical and sampling considerations help explain discrepancies among different detection efforts, including the one presented here, and provide considerations for the establishment of monitoring protocols to detect the presence of transgenes among structured populations of landraces

PERCEPCIÓN SOBRE IGUALDAD DE GÉNERO EN ESTUDIANTES DE INGENIERÍA (PERCEPTION ON GENDER EQUALITY IN ENGINEERING STUDENTS)

ResumenEn la última década parece que la desigualdad de género se está reduciendo, sin embargo queda mucho por hacer, particularmente en las Instituciones educativas. En este trabajo se presenta una primera aproximación del estudio de la equidad de género en una muestra significativa y aleatoria de estudiantes de primer semestre de ingeniería. Se aplicó un instrumento conformado por 30 ítems relacionados con la percepción de los estudiantes sobre el tema de la igualdad de género. Los resultados muestran que los estudiantes encuestados han vivido alguna situación de discriminación debido a que algún profesor los ha discriminado con favoritismos y ofensas verbales; otros más manifiestan haber sido discriminados por sus mismos compañeros debido a su apariencia física o por aspectos socioeconómicos, entre otras causas. Por tal motivo, es urgente considerar el impacto de la asociación de roles a mujeres y hombres según el género sobre la formación integral de los estudiantes. Palabra(s) Clave:desigualdad social, diferenciación social, influencia social, rol de géneros.  AbstractIn the last decade it seems that gender inequality is shrinking, however much remains to be done, particularly in educational institutions. This paper presents a first approach to the study of gender equity in a significant and random sample of first-year engineering students. An instrument consisting of 30 items related to the students' perception on the subject of gender equality was applied. The results show that the students surveyed have experienced some situation of discrimination because some teacher has discriminated against them with favoritism and verbal offenses; others claim to have been discriminated against by their peers due to their physical appearance or socioeconomic aspects, among other causes. For this reason, it is urgent to consider the impact of the association of roles to women and men according to gender on the integral formation of students.Keywords:social inequality, social differentiation, social influence, gender role

Synthesis by wet chemistry and characterization of LiNbO3 nanoparticles

Actually, lithium niobate (LiNbO3) has been used for optical wavelength conversion and ultrafast optical signal processing because of its outstanding rapid nonlinear optical response behavior, low switching power and broad conversion bandwidth. LiNbO3nanoparticles, which belong to the ferroelectric oxide class, were synthesized by chemical reaction with wetchemistry. Their sizedistributionwascenteredaround200 nm. Xray diffraction (XRD) and scanning electron microscopy (SEM) were used to further investigate the quality of the obtained LiNbO3powders.The present work shows thatby employingthis chemical method the correct stoichiometric phasewas obtained. This wascorroborated by XPS (X-Ray Photoelectron Spectroscopy) results. Also, the nanoparticles showed a defined crystallinity and uniform morphology. This way of obtaining nanoparticles is innovative because of its low cost and simple way to reproduce it. It isan important method of increasing the surfacearea, controlling thephase purityand reducing theparticle size distribution. The samples were obtained under low temperature annealing at500, 650 and 800 ºC. Those features can be controlled using variables such temperature, time of synthesis,and calcination. In previous worksit wasfound that hydrothermal methods offer many advantages over conventional ceramic synthesis methods

ACTUALIZACIÓN DEL PLAN DE ESTUDIOS DE LA LICENCIATURA EN TURISMO ALTERNATIVO DESDE EL MODELO INTERCULTURAL

En el periodo de 2017 a 2018 se actualizó el plan de estudios de la licenciatura en turismo alternativo, fue aprobada y puesta en marcha para dar soluciones a las principales problemáticas de los pueblos originarios del estado mexicano de Puebla, quienes encontraron en el turismo una opción para generar divisas aprovechando sus recursos bioculturales. El objetivo de este artículo es analizar la actualización realizada desde la educación intercultural. Las conclusiones muestran como incide la educación mexicana desde la hegemonía educativa en el modelo intercultural, con la finalidad de formar pensadores críticos que coloquen a los pueblos originarios en el centro del desarrollo turístico, así, combatir la pobreza y la marginación desde una planeación con base comunitaria

Del castigo a la humanización. Adolescentes en Centros de Justicia Juvenil: percepciones y reflexiones

El presente trabajo pretende aproximar la perspectiva de los Adolescentes en Conflicto con la Ley (en adelante ACL) sobre su proceso reeducativo y de paulatina recuperación de la libertad. ¿Existe algún contexto para el aprendizaje más complejo que el de una institución que limita las libertades? Este trabajo proyecta que los contextos basados en metodologías de acompañamiento humano, vinculación afectiva y socioeducativa, constituyen verdaderos espacios de transformación y de empoderamiento de los ACL. Eleva la importancia del principio de resocialización en la recuperación de hábitos prosociales de los delincuentes juveniles. Este artículo reproduce los resultados de una investigación longitudinal en la que participaron 157 ACL ingresados entre los años 2008 a 2012 en distintos centros públicos de Justicia Penal juvenil. El principio de resocialización del ACL nace al albor de estrategias para la transformación y aprendizaje desde contextos inclusivos. Por tanto, los recursos personales y ambientales, se fusionan en un proceso de intercambio que incide en la reflexión del individuo. Las vivencias de los ACL convergen con las prácticas educativas recibidas. La técnica etnográfica del relato de vida nos traslada al imaginario analítico de los ACL

Integrating Lean Six Sigma and discrete-event simulation for shortening the appointment lead-time in gynecobstetrics departments: a case study

Long waiting time to appointment may be a worry for pregnant women, particularly those who need perinatology consultation since it could increase anxiety and, in a worst case scenario, lead to an increase in fetal, infant, and maternal mortality. Treatment costs may also increase since pregnant women with diverse pathologies can develop more severe complications. As a step towards improving this process, we propose a methodological approach to reduce the appointment lead-time in outpatient gynecobstetrics departments. This framework involves combining the Six Sigma method to identify defects in the appointment scheduling process with a discrete-event simulation (DES) to evaluate the potential success of removing such defects in simulation before we resort to changing the real-world healthcare system. To do these, we initially characterize the gynecobstetrics department using a SIPOC diagram. Then, six sigma performance metrics are calculated to evaluate how well the department meets the government target in relation to the appointment lead-time. Afterwards, a cause-and-effect analysis is undertaken to identify potential causes of appointment lead-time variation. These causes are later validated through ANOVA, regression analysis, and DES. Improvement scenarios are next designed and pretested through computer simulation models. Finally, control plans are deployed to maintain the results achieved through the implementation of the DES-Six sigma approach. The aforementioned framework was validated in a public gynecobstetrics outpatient department. The results revealed that mean waiting time decreased from 6.9 days to 4.1 days while variance passed from 2.46 days2 to 1.53 days2

Social interactions and business portfolio among vegetable produc-ers in central Mexico

Objective: Analyze social interactions and business portfolio of vegetable producers in Central Mexico. Design/methodology/approach: we worked with 16 small vegetable producers. Semi-structured questionnaires and periodic monitoring were used in field to collect data. A Social Network analysis was carried out to know social interactions between producers, and the Boston Consulting Group (BCG) and Ansoff matrix for the business portfolio. Results: We found that the products with potential in the market were lettuce and nopal. Broccoli and squash represent low sales and low utility. Producers with a higher degree of centrality grow lettuce, broccoli and squash, so we suggested to develop strategies for introducing nopal. Limitations on study/implications: It was necessary to deep in market and consumers analysis.Objective: To analyze the social interactions and business portfolio of vegetable producers in central Mexico. Design/methodology/approach: Work was conducted with 16 small-scale vegetable producers. Semi-structured questionnaires and periodic monitoring were used in the field to collect data. A Social Network analysis was carried out to understand the social interactions between producers, and the Boston Consulting Group (BCG) and Ansoff matrix was used for the business portfolio. Results: The study found that the products with potential in the market were lettuce and nopal. Broccoli and squash represent low sales and low utility. Producers with a higher degree of centrality grow lettuce, broccoli and squash, so we suggested developing strategies for introducing nopal. Limitations on study/implications: It was necessary to delve into market and consumers analysis