La metodología de series de tiempo fue empleada en el presente estudio para comparar diferentes métodos de pronósticos en series de rendimiento de granos básicos (maíz, frijol, trigo y arroz) en México, con el objetivo de predecir sus valores en el corto plazo. Los pronósticos se realizaron empleando los modelos Autoregressive Integrated Moving Average (ARIMA) (1,0,1) para maíz, Modelo de Brow con α = 0.202 para frijol, Suavización Exponencial Simple con α = 0.7576 para trigo y Modelo de Holt con α = 0.5024 y β = 0.0366 para arroz. Los resultados indican que en el corto plazo los rendimientos de maíz, frijol y arroz se incrementarán, mientras que los rendimientos de trigo se mantendrán constantes. Respetando estas estimaciones de rendimiento, manteniendo constante la superficie cultivada y el consumo per cápita de granos básicos, y considerando diferentes escenarios de población, a largo plazo México solo será autosuficiente en la producción de frijol. Así, los pronósticos obtenidos en este trabajo pueden ser utilizados en la toma de decisiones de producción y compra-venta de granos.

BACKGROUND: Measurements of inspiratory capacity (IC) and vital capacity (VC) are used to recognize dynamic hyperinflation, but appropriate reference values are required to achieve accurate clinical interpretations. Altitude above sea level is a potential determining factor for lung volumes, including IC and VC. OBJECTIVE: To describe IC and VC for healthy people who live in Mexico City at an altitude of 2,240 m above sea level. METHODS: Healthy subjects ages 9-81 y completed slow spirometry by following 2005 American Thoracic Society/European Respiratory Society standards. Once associations were explored, linear regression models were constructed and values were compared with those from previously published equations. RESULTS: A total of 441 healthy subjects (55.1% women) participated. The mean age was 32 y (minimum age, 9 y; maximum age, 81 y). IC and VC measurements were associated with sex, age, height, and weight. An accelerated increase in IC and VC was evident from 9 to 20 y of age, followed by a gradual decrease in both sexes. In general, IC was higher in our population than predicted by previously published reference equations. CONCLUSIONS: IC in healthy people at 2,240 m above sea level was higher than that of previous reports about European and Latin-American subjects of the same height, sex, and age who were at sea level. The present study provided robust reference values for persons who lived at a moderate altitude.

In crop science, tools of non-linear dynamics, fractals, chaos, intermittency and self-organized criticality may be employed and applied to the analysis of spatial variability and temporal behavior of agro-meteorological variables, soil properties, plant attributes, commercial yields, and prices of the agricultural products in order to gain knowledge about underlying complex processes. A search on the occurrence of particular scaling laws in Mexico's normalized yearly mean grain yield anomaly series of maize (Zea mays L.), beans (Phaseolus vulgaris L.), wheat (Triticum aestivum L.) and rice (Oriza sativa L.), using a variography approach is reported in this work. Additionally, power spectrum determination, time-frequency analysis, and estimation of Lyapunov exponent were performed for each profile in order to obtain useful information on the frequency contents and signs at which important frequencies occur as well as to determine their sensitivity to initial conditions. Fractal analysis gives us the order maize < wheat < rice < beans of sensitivity to external forcings, which was the same as that obtained through the Lyapunov exponent values. Results confirm that the final outputs (crop yields) in agricultural systems are affected by the magnetic and sunspot cycles of the Sun, the El Niño Southern Oscillation (ENSO), and the quasi-biannual oscillation, and possibly by the so-called heliospheric mid-term-quasi-periodicities, which act on different time (or spatial and spatial-time) scales. In particular, the maize normalized year anomaly series is clearly correlated with March, April, May and June series of the ENSO index.

Here, we present an assessment of long-term trends in the O3 weekend effect (WE) occurrences and spread within the Mexico City (MCMA), Guadalajara (GMA), and Monterrey (MMA) metropolitan areas, which are the three largest metropolitan areas (MAs) of Mexico and concentrate around 33% of the total population in the country. Daytime averages and peak differences in O3 concentrations from weekdays to weekends were used as a proxy of WE occurrence. All MAs exhibited the occurrence of WE in all years at least in one monitoring site. Substantial differences in O3 daytime averages and peaks from weekdays to weekends have decreased over time in all MAs, and since 1998 and 2013 for the MCMA and GMA, respectively, higher O3 levels during weekends are typical during most of the year. The largest variations in the O3 WE were observed at downwind and urban core sites of the MCMA and GMA. Significant increasing trends (p < 0.05) in the O3 WE magnitude were observed for Sundays at all sites within the MCMA, with trends in annual averages ranging between 0.33 and 1.29 ppb O3 yr−1. Within the GMA, for Sundays, fewer sites exhibited increasing trends in the WE occurrence and at lower growth rates (0.32 and 0.48 ppb yr−1, p < 0.1) than within the MCMA, while within the MMA no apparent trends were observed in marked contrast with the MCMA and GMA. Our findings suggest that policies implemented have been successful in controlling weekday ground-level O3 within the MCMA and GMA, but further actions must be introduced to control the increases in the O3 WE magnitude and spread.

Objetivo. Identificar Escherichia coli O157:H7 presente en heces diarreicas de rumiantes lactantes con síndrome diarreico y seguridad de ingesta de calostro. Materiales y métodos. Se realizó un muestreo de 316 rumiantes durante el período de agosto 2015 a marzo 2016 en los municipios de Río Grande, General Enrique Estrada, Morelos y Calera de Víctor Rosales del estado de Zacatecas, 67 de bovinos, 183 de ovinos y 66 de caprinos. Resultados. Se identificaron en medio cromogénico CHROMagarTM: 260 coliformes, 78 Escherichia coli O157:H7, 16 Proteus spp., y 25 colonias de bacterias sin identificar con este medio, encontrándose una incidencia de Escherichia coli O157:H7 de 22.03% en los cuatro municipios. Conclusiones. Escherichia coli O157:H7 es la segunda bacteria encontrada en heces de rumiantes con un 22% de incidencia, la cual es un factor de riesgo de muerte en rumiantes lactantes (menos de 21 días de nacidos) causando pérdidas económicas y riesgo para la salud de la población del estado de Zacatecas.