Biodiversity and coffee culture in Mexico

Coffee is grown in agro-ecosystems designed by humans in tropical rain forests. Under diversified shade coffee retains much of the structure and functioning of forest ecosystems. After cereals, coffee is the agricultural product moving major currencies in international markets. It is produced in 50 countries by indigenous and peasants. In order to evaluate the coffee culture of central Veracruz region in Mexico, coffee production systems were studied and social organization manners were identified. The project had a transdisciplinary design. The network consists of 100 scholars, 10 organizations of producers and 109 companies in 52 municipalities. In four years (2010-2013), 254 meetings were held with the participation of 6,400 persons. Each activity was thought looking at farmers, their business project and its own culture.El café se produce en agro-ecosistemas diseñados por los seres humanos, a partir de bosques tropicales húmedos. El cafetal bajo la sombra conserva una gran parte de la estructura y funcionamiento de los ecosistemas boscosos. Después de los cereales, el café es el producto agrícola que mayores divisas mueve en el mercado internacional. Se produce en 50 países, principalmente por indígenas y campesinos. Con el objeto de valorar la cultura cafetalera del centro de Veracruz en México, se estudiaron los sistemas de producción de café y se identificaron las formas de organización social. El proyecto ha tenido un diseño transdisciplinario. La red de este estudio está formada por 100 académicos, 10 organizaciones de productores y 109 empresas en 52 municipios. En cuatro años (2010-2013) se realizaron 254 eventos con 6.400 participaciones. Cada actividad se realizó teniendo en cuenta a los productores, su proyecto de empresa y su cultura

Problemática a la salud y riesgo ambiental por el uso de plaguicidas organofosforados por plantación de hortalizas en Vega de Metztitlán, Hidalgo

El estudio se realizó en el municipio Metztitlán, Hidalgo, México; la actividad agrícola se sustenta en el uso de plaguicidas, que han tenido impacto negativo en el ambiente y la salud de los trabajadores que los manipulan. Se investigaron las causas y efectos de la aplicación de plaguicidas en los cultivos. Se señalan alternativas y reglamentación para la aplicación de los plaguicidas y el manejo de los envases y residuos de estos productos. Se realizaron dos encuestas: en la comunidad de la Laguna y San Cristóbal y en Metztitlán, consistió riesgo a la salud e impacto al ambiente de los plaguicidas. Los cultivos son de riego y temporal. Se utiliza el agua de río para lavar envases, formulación de mezclas y riego de cultivos. No hay control en el desecho de envases de plaguicidas. Han requerido hospitalización los agricultores-aplicadores intoxicados. El objetivo de la evolución de los riegos al ambiente y los peligros a la salud por la aplicación de plaguicidas se cumplió. Los resultados de las entrevistas, venta, aplicación y manejo de plaguicidas, así como la evaluación a los problemas a la salud se realizaron favorablemente.The study was conducted in the municipality Metztitlán, Hidalgo, Mexico; agricultural activity is based on the use of pesticides, which have had negative impact on the environment and health of the workers handling them. The causes and effects of the application of pesticides on crops were investigated. Alternatives and regulations for pesticide application and management of packaging and waste of these products are indicated. Two surveys were conducted: in the community of Laguna and San Cristobal and Metztitlán, consisted health risk and impact to the environment of pesticides. Crops are irrigated and temporary. River water is used for washing containers, formulation of mixtures and crop irrigation. There is no control on the disposal of pesticide containers. They have required hospitalization farmers-applicators intoxicated. The aim of the evolution of the risks to the environment and health hazards for pesticide application fulfilled. The results of the interviews, sales, application and handling of pesticides, as well as evaluating the health problems were performed favorably

Concentration and band offset dependence of the electronic basic transition of cubic InxGa1−xN/InyGa1−yN quantum wells

We calculate the transition energy from the first level of holes to the first level of electrons for cubic InxGa1−xN/InyGa1−yN quantum wells. We employ the empirical tight binding approach with an sp3s* orbital basis, nearest neighbour interactions and the spin–orbit coupling, together with the surface Green function matching method. For the alloy, we use the virtual crystal approximation. We take into account the strain in the well. We assume a value of 0.65 eV for the InN bandgap and 3.3 eV for the GaN gap. Using a value of 20% for the valence band offset, we study the transition energy behaviour varying the well width for the sets of concentrations x=0.3, y=0.02 and y=0.05; x=0.15, y=0.05; and x=0.16, y=0. For the concentrations x=0.16, y=0, we also study the influence of the band offset using values of 20%, 50% and 80% for the valence band offset. We compare our calculations with experimental data from hexagonal and cubic quantum wells, and with other theoretical calculations for cubic quantum wells. The comparison of the calculations with the experimental results from hexagonal quantum wells is good. The theoretical energy transitions are 0.35–0.5 eV higher than those obtained experimentally for cubic quantum wells

Cálculo de áreas planas en R2 usando las nuevas tecnologías

En la enseñanza de las matemáticas y en particular del cálculo diferencial e integral, el profesor busca que los conceptos correspondientes se puedan entender por los alumnos a través de ejemplos sencillos al principio, propone varias estrategias para encontrar la solución de un problema, trata de motivar a los estudiantes y de proporcionar ejemplos de aplicación. En varias de las asignaturas de matemáticas para estudiantes de ingeniería, un aspecto fundamental al analizar un tema en particular es usar al menos tres formas de representar un concepto: El aspecto analítico, el geométrico y el tabular. En el presente trabajo se muestra una estrategia alternativa complementaria para estudiar el concepto de la integral definida haciendo uso de software matemático

(E)-1-([1,1′-Biphen­yl]-4-yl)-2-(1,3,3-tri­methylindolin-2-yl­idene)ethanone

The title compound, C25H23NO, consists of a biphenyl-4-carbonyl unit attached to an exocyclic double bond group at position 2 of an indole unit, which presents methyl groups as substituents at positions 1 and 3. The mol­ecular conformation is s-cis with an E configuration, supported by weak intra­molecular C—H⋯O contacts involving the methyl groups and the carbonyl function. The rings of the biphenyl group are twisted by 37.13 (5)°. In the crystal, C—H⋯O and C—H⋯π inter­actions link the molecules

Tamaño y estructura poblacional de crocodylus acutus (cuvier 1807) (reptilia: crocodylidae) en el estero La Ventanilla, Oaxaca, México

A population of the American crocodile (Crocodylus acutus) protected through local participation was studied at La Ventanilla estuary in the coast of Oaxaca, during 8 months (October 2003-May 2004). Size, structure and sex ratio of this population were evaluated in order to provide demographic information of the American crocodile using two capturerecapture methods. A total of 21 adults (8 females, 13 males), 11 subadults (5 females, 6 males), 88 juveniles (14 females, 62 males) and 23 neonates were captured, measured and individually marked. Goodness-of-fit tests for the Jolly-Seber model showed that our population data violated the assumption of equal probability of capture and resulted in a skewed estimate of population size. However, goodness-of- fit tests for the geometric estimator of the capture frequency model applied to the same capture-recapture data showed recapture frequencies conform to it. Population size estimates for this model were 29.6 ± 9.1 adults, 37.1 ± 6.6 subadults, and 682.5 ± 39.2 juveniles. Population structure does not fit the normal distribution (d=39.5,P>0.05), most individuals belonging to lower size classes (16.2% in class I, 61.5% in class II), with few subadults (9.1% in class III) and adults (13.3 %, I class IV). Overall sex ratio was significantly skewed towards males (3 males: 1 female). This analysis provides information for future management strategies for the C. acutus population at La Ventanilla estuary.Se estudió una población del cocodrilo de río (Crocodylus acutus) protegida por medio de la participación local en el estero La Ventanilla, Oaxaca, México, entre octubre del 2003 y mayo del 2004. Se estimó el tamaño, estructura y proporción de sexos de esta población para aportar información demográfica del cocodrilo de río mediante la aplicación de dos métodos de captura-recaptura. Se capturaron, midieron y marcaron 21 adultos (8 hembras, 13 machos), 11 subadultos (5 hembras, 6 machos), 88 juveniles (14 hembras, 62 machos) y 23 neonatos. La estimación del tamaño de la población mediante el modelo de Jolly-Seber resultó sesgada debido a que las pruebas de bondad de ajuste detectaron que las historias de captura no se ajustaron al supuesto de igual probabilidad de captura de este modelo. Las mismas historias de captura mostraron un ajuste significativo al modelo del estimador geométrico de frecuencia de capturas y las estimaciones de tamaño poblacional con este modelo fueron de 29.6 ± 9.1 adultos, 37.1 ± 6.6 subadultos y 682.5 ± 39.2 juveniles. La estructura por clases de tamaño de la población de C. acutus no sigue una distribución normal y la mayor parte de los organismos están distribuidos en las clases de menor tamaño (clase I=16.1%, clase II=61.5%), con poca representación de subadultos (clase III= 9.19%) y de adultos (clase IV=13.3%). La proporción de sexos esta significativamente sesgada hacia los machos (3 machos:1 hembra). Este análisis proporciona información para el futuro diseño de estrategias de manejo de la población de C. acutus en el estero La Ventanilla

Profitability of Corn (Zea mays L.) Grown in Milpa Production Systems in Oaxaca, Puebla, and Veracruz, Mexico

OBJECTIVE: To compare the profitability of corn cultivation under the milpa system in Oaxaca, Puebla, and Veracruz. METHODOLOGY: A sample of 91 producers from Villa de Zaachila, Oaxaca, Chalchicomula de Sesma, Puebla, and Tequila, Veracruz, was interviewed about corn production by milpa production system. The average yields per hectare, costs, sale price and total income are compared, and the Cost Benefit Ratio (CBR) of the milpas in each municipality was interpreted. RESULTS: Maize production in Villa de Zaachila presented a modern agriculture with total production costs of 13,650 $ha-1, yield 2,257 kg ha-1, total income 23,429.27$ ha-1 and RBC 1.72. In Chalchicomula de Sesma, a traditional agriculture destined for commercialization to intermediaries, its total costs were 12,380 $ha-1, yield of 2,456 kg ha-1, total income 12,280.00$ ha-1 and RBC 0.99. In Tequila, a subsistence agricultural, with total production costs of 7,350 $ha-1, yield 964 kg ha-1, total income of 6,748.00$ ha-1 and RBC 0.92. STUDY LIMITATIONS: The data is taken from an exploratory sample, limited in time and space. Versions or productive practices not sampled could be omitted, with technical-economic specificities different from those presented in this study. CONCLUSIONS: The contrasting modifications in the structure, function, and logic of the milpa for the 2020-2021 cycle, allowed a profitable agroecosystem in Villa de Zaachila; however, it was not profitable in Chalchicomula de Sesma and Tequila.Objective: To compare the profitability of corn cultivation under the milpa production system in Oaxaca, Puebla, and Veracruz.Methodology: Ninety-one producers, from Villa de Zaachila, Oaxaca, Chalchicomula de Sesma, Puebla, and Tequila, Veracruz, Mexico, were interviewed about corn production in milpa production systems. Average yield per hectare, costs, selling price, and total income were compared and the Cost Benefit Ratio (CBR) of the milpas of eachmunicipality was analyzed.Results: In Villa de Zaachila, corn production is carried out in a modern agriculture system with a $13,650 ha -1 total production costs, a 2,257 kg ha -1 yield, a$23,429.27 ha -1 total income, and a 1.72 CBR. The producers of Chalchicomula de Sesma use a traditional agriculture system and the production is sold to intermediaries, with a $12,380 ha -1 total cost, a 2,456 kg ha -1 yield, a$12,280.00 ha -1 total income, and a 0.99 CBR. InTequila, a subsistence agriculture is used, with a $7,350 ha -1 total production cost, a 964 kg ha -1 yield, a$6,748.00 ha -1 total income, and a 0.92 CBR.Study Limitations: The data were taken from an exploratory sample, limited in time and space. Non-sampled versions or productive practices could have been omitted, when technical-economic specificities are different from those shown in this study.Conclusions: The contrasting modifications in the structure, function, and logic of the milpa (2020-2021 cycle) resulted in a profitable agroecosystem in Villa de Zaachila; however, Chalchicomula de Sesma and Tequila had a non-profitable cycle

Cellulose-Based Polymer Composite with Carbon Black for Tetrahydrofuran Sensing

This work focused on studying the sensing efficiency of tetrahydrofuran (THF) by composite films made of thin layers of a cellulose-based polymer and carbon black. We analyze the reproducibility, durability, desorption time, and the sensitivity percent as a function of the amount of solvent. Two types of experiments were conducted, (1) progressive sensing test (PST) which consisted of progressively increasing the amount of solvent from 0.1 mL increments up to 1.0 mL and (2) multiple sensing test (MST) where the layers were subjected to consecutive pulses of the same amount of solvent, with a minimum of 0.1 mL and a maximum of 0.4 mL. The response and desorption times were a few seconds, and the sensitivity percent ranged from 1% to 170% and was dependent on the solvent quantity

Towards 50% Efficiency in Solar Cells

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