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766 resultados encontrados para: AUTOR: Hernández, E
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1.
Artículo
A 2D image-based approach for CFD validation of liquid mixing in a free-surface condition
Rodríguez Ocampo, P. E. (autor) ; Ring, M. (autor) ; Hernández Fontes, J. V. (autor) ; Alcérreca Huerta, Juan Carlos (autor) ; Mendoza Ramírez, Eduardo (autor) ; Gallegos Diez Barroso, Gabriel (autor) ; Silva, R. (autor) ;
Disponible en línea
Contenido en: Journal of Applied Fluid Mechanics Volume 13, número 5 (2020), p. 1487-1500 ISSN: 1735-3645
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Resumen en: Inglés |
Resumen en inglés

This study proposes an image-based approach to evaluate the validity of numerical results for cases where the setup can be assumed to be two-dimensional (2D) and mixing between liquids of different densities occurs under a free-surface condition. The proposed methodology is based on the estimation of the relative errors of the model through density matrices generated from images of the experimental and numerical results (i.e., post-processing snapshots of the density field). To demonstrate the use of the methodology, experimental tests and numerical simulations were performed for a double-dam-break problem with two miscible liquids. For the experiments, a high-speed camera was employed to capture details of the fluid interactions after the dam breaking. For the numerical simulations, an OpenFOAM® multiphase solver was employed to reproduce the benchmarking tests. Three turbulence approaches were tested: a zero-equation RANS model, a two-equation (k-epsilon) RANS model, and a Large-Eddy Simulation (LES) model. The experimental results compared favorably against the numerical results, with average drelative errors of ~17 and ~19% for the zero-equation and the two-equation turbulence models, respectively, and ~14% for the LES model. From the results obtained, it can be inferred that the two-equation (k-epsilon) model had limitations in reproducing the mixing between the liquid phases in terms of relative errors. The LES model reproduces the mixing between phases more accurately than zero and two-equation RANS models, which were seen to be more suitable for capturing the formation of large eddies in the initial phase of the experiment. The present methodology canbe improved and extended for different multiphase flow configurations.


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Resumen en: Español |
Resumen en español

Este libro, pequeño y colorido, es un compendio de fichas didácticas creadas para el huerto educativo de El Colegio de la Frontera Sur en San Cristóbal de Las Casas, Chiapas. Están organizadas según la familia botánica, y llevan una franja de color distinto para cada familia en la parte superior. Así, nos podemos enterar, por ejemplo que aunque parecen muy distintas en nuestros platos, el cilantro, el hinojo y la zanahoria son todas primas. Esto tiene importancia práctica porque las plantas emparentadas muchas veces comparten plagas y enfermedades, así que no conviene combinarlas en un policultivo ni secuencialmente en una rotación. Puedes imprimir éstas fichas y usarlas como material de apoyo para aprender la información que contienen, repartirlas entre visitantes a tu huerto para que busquen las plantas, o incluso convertirlas en etiquetas para tus plantas. ¡Qué las disfrutes!.


3.
Artículo
*Solicítelo con su bibliotecario/a
Attraction of Chelonus insularis to host and host habitat volatiles during the search of Spodoptera frugiperda eggs
Roque Romero, Linnet (autora) ; Cisneros Hernández, Juan (autor) ; Rojas, Julio C. (autor) ; Ortiz Carreón, Fabián Rubén (autor) ; Malo Rivera, Edi Álvaro (autor) ;
Disponible en línea
Contenido en: Biological Control Vol. 140, no. art. 104100 (January 2020), p. 1-7 ISSN: 1049-9644
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Egg parasitoids use different strategies than do larval parasitoids to locate hosts. The wasp Chelonus insularis Cresson is a key egg parasitoid of the fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), one of the main insect pests of maize (Zea mays L.). Using a Y-glass tube olfactometer, in this study we determined the roles of chemical cues from host and host habitats used by C. insularis when they search for FAW eggs. We found that C. insularis females were attracted to volatiles emitted by host egg masses, host females (i.e., sex pheromone), and maize seedlings with and without FAW eggs. The responses of the parasitoids to host and maize seedling volatiles increased after their first oviposition experience, making it possible for females to discriminate between maize seedlings with and without FAW eggs. The information generated in this study may be useful in the development of future biological control programs of S. frugiperda using C. insularis in either augmentation or conservation approaches.


4.
- Artículo con arbitraje
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Resumen en: Inglés |
Resumen en inglés

The West Indian fruit fly, Anastrepha obliqua (Macquart), is the second most important tephritid fruit fly in Mexico, infesting mango, hog plum and guava fruits. To control this pest, the Mexican government has implemented the use of the sterile insect technique (SIT), which involves the mass production, sterilization and release of flies. However, the A. obliqua laboratory males used in SIT are selected to a lesser extent by the wild females during competitiveness tests. The objective of this study was to compare the effects of males fed on fruit fly food enriched with Providencia rettgeri to those in males fed on food alone, assessing male mating competitiveness, capture of females using traps baited with males fed with the enriched diet and sex pheromone components. The results indicated that males fed with the diet enriched with P. rettgeri had increased mating competitiveness and captured more females in the field cage tests. However, no difference was observed in the proportion of volatile sex pheromone components identified during the calling of A. obliqua males. The results suggest the value of incorporating bacteria into the mass rearing technique of A. obliqua adults in order to improve the sexual competitiveness of males from the laboratory compared to wild males.


5.
Artículo
Cebos feromonales para la captura de spodoptera frugiperda (j. e. smith) (lepidoptera: noctuidae) en cultivos de maíz adyacentes a cultivos de fresas
Cruz Esteban, Samuel (autor) ; Hernández Ledesma, Patricia (autora) ; Malo Rivera, Edi Álvaro (autor) ; Rojas, Julio C. (autor) ;
Disponible en línea
Contenido en: Acta Zoológica Mexicana. Nueva Serie Volume 36, e3612255 (febrero 2020), p. 1–15 ISSN: 2448-8445
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Resumen en: Español | Inglés |
Resumen en español

El gusano cogollero, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), es una de las principales plagas del maíz y el sorgo, además de que este insecto empieza a ser una amenaza para el cultivo de fresa en Michoacán, México. Debido al daño que puede causar este insecto, es necesario contar con un sistema de monitoreo de sus poblaciones para detectar infestaciones tempranas e implementar su control a tiempo. Bajo este escenario, el uso de trampas cebadas con feromona sexual puede ser útil para atraer a los machos. En este estudio, se comparó la efectividad de una feromona desarrollada a partir de poblaciones mexicanas de S. frugiperda contra cuatro formulaciones comerciales, tres formuladas en el extranjero y una en México, en cultivos de maíz adyacentes acultivos de fresas. También, se evaluó el efecto del color de la trampa en las capturas de S. frugiperda, usando uno de los cebos que presentó mayores capturas. Las trampas cebadas con cebo optimizado para poblaciones mexicanas (EcoTap) y con el cebo comercial formulado en el país (Phero-SF) fueron las que capturaron más machos de S. frugiperda y menos insectos no blancos, comparado con las trampas cebadas con los otros cebos. Uno de los hallazgos inesperados fue la captura de machos del gusano cortador, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), por las trampas cebadas con EcoTap o Phero-SF. El color de la trampa no fue una variable significativa para la captura de machos de S. frugiperdao A. ipsilon. Estos resultados pueden ser de importancia para el desarrollo de un sistema de monitoreo o trampeo masivo de S. frugiperda en las regiones mexicanas donde el maíz y sorgo son los principales cultivos, o en aquellos orgánicos de fresas que pueden estar amenazados por este insecto polífago.

Resumen en inglés

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is one of the main pests of maize and sorghum, in addition this insect begins to be a threat for strawberry crops in Michoacán, Mexico. Thus, it would be worth to have a monitoring system to detect early infestations of S. frugiperda and implement their control in time. Under this scenario, the use of traps baited with the sex pheromone may be useful to catch males. In this study, we compared the effectiveness of a pheromone lure developed from Mexican populations of S. frugiperda against four commerciallures, three formulated abroad and one in Mexico, in maize crops adjacent to strawberries ones. Additionally, we analyzed the effect of the trap color. It was found that the traps baited with lure optimized for Mexican populations (EcoTap) or with the commercial lure formulated in Mexico (Phero-SF) captured more S. frugiperda males and less non-target insects compared to traps baited with the other lures. One unexpected finding was the caught of black cutworm males, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), by the traps baited with EcoTap or Phero-SF lures. The trap colour did not have a significant effect on the capture of S. frugiperda or A. ipsilon males. The results obtained here may be used for monitoring or mass trapping S. frugiperdain the Mexican regions where maize and sorghum are the main crops or in organic strawberry crops that may be threatened by this polyphagous insect.


6.
Artículo
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Resumen en inglés

Natural Protected Areas (NPAs) are consider adequate tools for biodiversity conservation. Currently in Mexico there are 182 federal NPAs classified according to their management objectives. Chiapas is the Mexican state with the highest number of decreed NPAs and also allocates one of the largest territorial extensions for its protection. Unlike other taxa, and despite their proven ability to respond to ecosystem changes, the study of dung beetles within Mexican NPAs has been underestimated, as they are not considered as a priority group within their management and conservation programs. Based on the review of information available in publications and database on dung beetles, a list of 112 species and seven subspecies recorded in 16 of the 19 federal NPAs established in Chiapas is presented.

The species recorded by each NPA show a significant correlation with the number of publications, but a low percentage of them correspond to studies with systematic samplings and most of the species reported in several of the NPAs come from sporadic records, which prevents the study of several basic and applied aspects of dung beetles in the region. Therefore, studies that extensively analyze the communities of arthropod groups, such as the Scarabaeinae, are necessary to understand their response to changes in the ecosystem at local and regional scale. It is advisable that these insects be included in the previous justifying studies for the designation or establishment of NPAs and, in turn, considered in the biological monitoring programs of these areas for their capacity as a bioindicator group.


7.
Artículo
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Resumen en: Inglés |
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Background: Reliable information about the spatial distribution of aboveground biomass (AGB) in tropical forests is fundamental for climate change mitigation and for maintaining carbon stocks. Recent AGB maps at continental and national scales have shown large uncertainties, particularly in tropical areas with high AGB values. Errors in AGB maps are linked to the quality of plot data used to calibrate remote sensing products, and the ability of radar data to map high AGB forest. Here we suggest an approach to improve the accuracy of AGB maps and test this approach with a case study of the tropical forests of the Yucatan peninsula, where the accuracy of AGB mapping is lower than other forest types in Mexico. To reduce the errors in field data, National Forest Inventory (NFI) plots were corrected to consider small trees. Temporal differences between NFI plots and imagery acquisition were addressed by considering biomass changes over time. To overcome issues related to saturation of radar backscatter, we incorporate radar texture metrics and climate data to improve the accuracy of AGB maps. Finally, we increased the number of sampling plots using biomass estimates derived from LiDAR data to assess if increasing sample size could improve the accuracy of AGB estimates.

Results: Correcting NFI plot data for both small trees and temporal differences between field and remotely sensed measurements reduced the relative error of biomass estimates by 12.2%. Using a machine learning algorithm, Random Forest, with corrected field plot data, backscatter and surface texture from the L‑band synthetic aperture radar (PALSAR) installed on the on the Advanced Land Observing Satellite‑1 (ALOS), and climatic water deficit data improved the accuracy of the maps obtained in this study as compared to previous studies (R²=0.44 vs R²= 0.32). However, using sample plots derived from LiDAR data to increase sample size did not improve accuracy of AGB maps (R²= 0.26). Conclusions: This study reveals that the suggested approach has the potential to improve AGB maps of tropical dry forests and shows predictors of AGB that should be considered in future studies. Our results highlight the importance of using ecological knowledge to correct errors associated with both the plot‑level biomass estimates and the mis‑match between field and remotely sensed data.


8.
Artículo
Jardín botánico y arboretum: estrategias de conservación forestal en paisajes antropizados del trópico mexicano
Esparza Olguín, Ligia Guadalupe (autora) ; Maya Martínez, Aixchel (autora) ; Hernández García, Gonzalo (autor) ; Martínez Romero, Eduardo (autor) ;
Disponible en línea
Contenido en: Revista Mexicana de Ciencias Forestales Volumen 11, número 60 (julio-agosto 2020), p. 50-77 ISSN: 2007-1132
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Resumen en: Español | Inglés |
Resumen en español

Los jardines botánicos y arboreta son considerados instrumentos de conservación relevantes a partir de las alarmantes tasas de deforestación que tienen las selvas y la consecuente afectación de su diversidad. En este trabajo se analizó la diversidad, el estatus de conservación y el uso po tencial de las especies arbóreas en el jardín botánico (JB) y el arboretum (A) del Centro de Investigación y Transferencia de Tecnología Forestal El Tormento. En el primero, el muestreo se realizó en un área total de 9 375 m²; mientras que, en el segundo el muestreo se hizo en 1.6 ha. Ambos espacios representan vegetación de selva mediana subperennifolia, con 11 871 individuos pertenecientes a 92 especies y 35 familias. El JB fue 1.6 veces más diverso que A. Se documentaron 15 usos potenciales en 98.9% de los taxones con al menos un uso registrado. Entre los taxa de ambas colecciones, se tienen siete clasificadas en la lista roja de la IUCN, dos en CITES y ocho en la NOM-059-SEMARNAT-2010. Estos resultados subrayan la importancia del jardín botánico y el arboretum como reservorios de especies forestales útiles desde muy diversas perspectivas y como espacios de conservación de taxa amenazados de las selvas medianas subperennifolias del sur de México.

Resumen en inglés

Botanical gardens and arboreta are considered relevant conservation instruments based on the alarming deforestation rates that forests have and the consequent impact on their diversity. In this paper, the diversity, conservation status and potential use of tree species in the botanical garden (JB) and arboretum (A) of the El Tormento Forest Technology Research and Transfer Center were a nalyzed. In the first, the sampling was carried out in a total area of 9 375 m²; while in the second the sampling was done in 1.6 ha. Both spaces represent vegetation of medium sub-evergreen forest, with 11 871 individuals which belong to 92 species and 35 families. JB was 1.6 times more diverse than A. 15 potential uses were documented in 98.9 % of the species with at least one registered use. Among the species in both collections, there are seven classified in the IUCN red list, two in CITES and eight in the NOM-059-SEMARNAT-2010. These results underscore the importance of the botanical garden and the arboretum as reservoirs of useful forest species from many different perspectives and as conservation spaces for threatened taxa from the medium-long sub-evergreen forests of southern Mexico.


9.
Artículo
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Resumen en: Español | Inglés |
Resumen en español

Las características de los humedales costeros son resultado de las interacciones hidrogeomorfológicas entre el continente y el océano, que causan un gradiente ambiental, que resulta en diferentes tipos de vegetación como manglares, popales, tulares, selvas y palmares inundables. Objetivo: Caracterizar las variables del hidroperiodo y fisicoquímicas del agua y suelo para determinar la relación que existe en el patrón de distribución de la vegetación en el Sistema de Humedales El Castaño (SHC). Metodología: Se establecieron 11 unidades de muestreo (UM) permanentes por estrato definidos: cinco en el manglar, dos en selvas inundables, dos en tular y dos en pastizal inundable. De mayo 2016 a octubre 2017 se caracterizó la vegetación y se muestreó mensualmente los niveles de inundación y parámetros fisicoquímicos del agua (superficial, intersticial y subterránea): salinidad, conductividad y pH; y el suelo: densidad aparente, porcentaje de humedad y potencial redox. Resultados: El manglar es el más cercano al mar, tiene la menor diversidad (H:1.66) y especies registradas (14), está dominado por Laguncularia racemosa y Rhizophora mangle y tiene los valores más altos de salinidad intersticial y subterránea, mayores a 10.8 ups, se mantiene inundado de 4 a 12 meses, su potencial redox es de 14.57 mV. Seguido está el manglar, tierra adentro, se ubican los remanentes de la selva inundable, (H:2.18 y 18 especies), dominada por Pachira aquatica, la salinidad intersticial y subterránea de 4.95 ups, permanece inundada de 0 a 6 meses y el potencial redox es de 119.07 mV. El tular, después de la selva, (H:1.92 y 16 especies), dominado por Typha domingensis, salinidad intersticial y subterránea de 6.1 ups, el tiempo de inundación es de 5 a 8 meses y potencial redox es de 125.9 mV.

El pastizal inundable, con menor influencia marina, es un humedal herbáceo modificado para uso ganadero, presentó los valores más altos de diversidad (H:3.44 y 50 especies), Paspalum conjugatum es la especie dominante, la salinidad intersticial y subterránea es menor a 0.5 ups, se mantiene inundado de 5 a 9 meses y el potencial redox es de 151.23 mV. Conclusiones: En cada tipo de vegetación, la estructura, composición y diversidad es diferente, con un alto recambio de especies que indica un gradiente definido por la salinidad.

Resumen en inglés

Distribution patterns and vegetation structure in the coastal wetland gradient in the Castaño, Chiapas, Mexico. Introduction: The characteristics of coastal wetlands are the result of hydrogeomorphological interactions between the continent and the ocean, which cause an environmental gradient, hat results in different vegetation types such as mangroves, freshwater marshes, swamp forests and palm swamps. Objective: To characterize the hydroperiod and physicochemical variables of water and soil and their effect on the distribution of vegetation in the Sistema de Humedales El Castaño. Methods: A total of 11 permanent sampling units (UM) were established by defined strata: five in the mangrove, two in swamp forest, two in freshwater marshes and two in the flooded pasture. From May 2016 to October 2017 the vegetation was characterized and the water levels and physicochemical parameters (superficial, interstitial and groundwater) were sampled monthly for: salinity, and pH; and the soil for: bulk density, humidity percentage, and redox potential.

Results: Mangroves are the closest to the sea, have the lowest diversity (H: 1.66) and species richness (14), they are dominated by Laguncularia racemosa and Rhizophora mangle, have the highest values of interstitial and groundwater salinity, (> 10.8 ups), remain flooded for 4 to 12 months per year, and have a redox potential of 14.57 mV. Immediately, inland, there are remnants of the swamp forests (H: 2.18 and 18 species), dominated by Pachira aquatica , with 5 ups interstitial and groundwater salinity, flooded from 0 to 6 months per year, with a redox potential of 119.07 mV. These forests are followed inland by freshwater marshes (H: 1.92 and 16 species), dominated by Typha domingensis with 6.1 ups interstitial and groundwater salinity, flooded for 5 to 8 months per year and a redox potential of 125.9 mV. Finally, furthest inland is the flooded pasture, a modified herbaceous wetland for cattle grazing (H: 3.44 and 50 species) dominated by Paspalum conjugatum , where interstitial and groundwater salinity is less than 0.5 ups, it stays flooded for 5 to 9 months and the redox potential is 151.23 mV. Conclusions: In each type of vegetation, the structure, composition, and diversity are different, with a high turnover of species that indicates a gradient defined by salinity. The vegetation in the SHC follows the patterns of typical organization of the tropical coastal wetlands, mangroves, swamp forests and herbaceous wetlands, in this case the freshwater marshes and flooded pastures. The factor that define the distribution of the vegetation is the salinity and the gradient that is observed are a function of the hydrological dynamics that depends on the mixing of marine and freshwater.


10.
Artículo
Resumen en: Inglés |
Resumen en inglés

Premise: Domestication usually involves local adaptation to environmental conditions. Cucurbita species are a promising model for studying these processes. Cucurbita moschata is the third major crop in the genus because of its economic value and because it displays high landrace diversity, but research about its genetic diversity, population structure, and phylogeography is limited. We aimed at understanding how geography and elevation shape the distribution of genetic diversity in C. moschata landraces in Mexico. Methods: We sampled fruits from 24 localities throughout Mexico. We assessed 11 nuclear microsatellite loci, one mtDNA region, and three cpDNA regions but found no variation in cpDNA. We explored genetic structure with cluster analysis, and phylogeographic relationships with haplotype network analysis. Results: Mitochondrial genetic diversity was high, and nuclear genetic differentiation among localities was intermediate compared to other domesticated Cucurbita. We found high levels of inbreeding. We recovered two mitochondrial lineages: highland (associated with the Trans-Mexican Volcanic Belt) and lowland. Nuclear microsatellites show that localities from the Yucatan Peninsula constitute a well-differentiated group. Conclusions: Mexico is an area of high diversity for C. moschata, and these landraces represent important plant genetic resources. In Mexico this species is characterized by divergence processes linked to an elevational gradient, which could be related to adaptation and may be of value for applications in agriculture. The Isthmus of Tehuantepec may be a partial barrier to gene flow. Morphological variation, agricultural management, and cultural differences may be related to this pattern of genetic structure, but further studies are needed.