Más allá de los colores del amaranto

JESUS ALFREDO ARAUJO LEON Víctor Aguilar Hernández Ivonne Sánchez del Pino SERGIO RUBEN PERAZA SANCHEZ ROLFFY RUBEN ORTIZ ANDRADE Ligia Guadalupe Brito Argáez (2022, [Artículo])

El amaranto tiene una amplia gama de colores atrayentes, desde amarillos, violetas hasta rojos intensos. Esta heterogeneidad de tonalidades llamó la atención de civilizaciones que se desarrollaron en todas las latitudes del continente americano, como es el caso del imperio azteca que integró este cultivo a su cosmovisión ceremonial para ofrendas a diferentes deidades, dejando una herencia prehispánica cautivadora de su historia. Más allá de los colores, el presente trabajo tiene como objetivo abordar las propiedades nutricionales y beneficios para la salud humana de la diversidad de fitoquímicos que son responsables de los interesantes colores del amaranto.

AMARANTHACEAE AMARANTHUS BETALAINAS METABOLITOS SECUNDARIOS MEXICO SALUD HUMANA BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA VEGETAL (BOTÁNICA) DESARROLLO VEGETAL DESARROLLO VEGETAL

Shopping for Ecological Indices? On the Use of Incidence-Based Species Compositional Similarity Measures

IAN MACGREGOR FORS FEDERICO ESCOBAR SARRIA JUAN FERNANDO ESCOBAR IBAÑEZ NATALIA MESA SIERRA FREDY ALEXANDER ALVARADO ROBERTO Rafael Rueda Hernández CLAUDIA ELIZABETH MORENO ORTEGA Ina Falfán ERICK JOAQUIN CORRO MENDEZ Eduardo Octavio Pineda Arredondo Amandine Bourg JOSE LUIS AGUILAR LOPEZ (2022, [Artículo])

"β-diversity has been under continuous debate, with a current need to better understand the way in which a new wave of measures work. We assessed the results of 12 incidence-based β-diversity indices. Our results of gradual species composition overlap between paired assemblages considering progressive differences in species richness show the following: (i) four indices (β-2, β-3, β-3.s, and βr) should be used cautiously given that results with no shared species retrieve results that could be misinterpreted; (ii) all measures conceived specifically as partitioned components of species compositional dissimilarities ought to be used as such and not as independent measures per se; (iii) the non-linear response of some indices to gradual species composition overlap should be interpreted carefully, and further analysis using their results as dependent variables should be performed cautiously; and (iv) two metrics (βsim and βsor) behave predictably and linearly to gradual species composition overlap. We encourage ecologists using measures of β-diversity to fully understand their mathematical nature and type of results under the scenario to be used in order to avoid inappropriate and misleading inferences."

Beta diversity Nestedness Replacement Richness difference Species turnover BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA VEGETAL (BOTÁNICA) ECOLOGÍA VEGETAL ECOLOGÍA VEGETAL

Grazing behavior of New Zeland holstein cows with access to shade

Rodolfo Ramírez-Valverde Juan Burgueño (2022, [Artículo])

Temperature and Humidity Index Artificial Shade CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA SHADING DAIRY COWS SOLAR RADIATION

Arreglos de antenas para radiación tipo Isoflux en satélites LEO con diferentes alturas orbitales

Antenna arrays for Isoflux radiation in LEO satellites at various orbital altitudes

Paulina Díaz De la Paz (2023, [Tesis de maestría])

En los últimos años, las constelaciones de satélites en órbita baja han ganado popularidad como infraestructura para ofrecer el servicio de Internet satelital, y se espera que su presencia siga en aumento. Para minimizar la latencia en la transmisión de datos, estos satélites suelen situarse en el rango inferior y medio de la órbita baja terrestre. Comúnmente, los satélites de estas constelaciones emiten una radiación que consiste en un único haz que concentra la potencia en una sola dirección. Sin embargo, debido a la curvatura de la Tierra, las ondas electromagnéticas radiadas por el arreglo de antenas abordo del satélite viajan distancias diferentes. Las ondas que se desplazan en dirección del nadir del satélite hacen un recorrido más corto en comparación con las que se propagan en las direcciones más distantes a este. Este fenómeno ocasiona pérdidas de potencia en los bordes del área de cobertura. Para compensar estas pérdidas, se propone el uso de arreglos de antenas de radiación tipo Isoflux. Estos arreglos distribuyen la densidad de potencia de manera uniforme en el área de cobertura, aumentando la ganancia en direcciones donde el trayecto es más largo. Lograr este tipo de radiación para satélites en órbita baja se vuelve más desafiante. Debido a la proximidad del satélite a la Tierra, es necesario que la radiación se extienda sobre una gran parte del plano de elevación, requiriendo un haz Isoflux que sobrepasa los 100 grados. Esta tesis presenta 18 diseños de arreglos de antenas para satélites en las alturas orbitales de 340 km, 550 km y 1150 km. Para el diseño de estos arreglos, se emplean las geometrías lineales, planares y anillos concéntricos, tanto periódicas como aperiódicas. La distribución de excitaciones de amplitud y la separación entre elementos de antena se optimizan utilizando algoritmos genéticos. La presente tesis incluye un análisis comparativo de las prestaciones de radiación y cantidad de elementos de los diseños presentados, categorizados por altura orbital.

In recent years, the utilization of low-Earth orbit satellite constellations as infrastructure for providing satellite Internet services has experienced substantial growth. The rise of this trend is likely to continue. These satellites are typically placed in the lower to mid-range of low-Earth orbit in order to reduce latency in data transmission. It is common for the antenna arrays on these satellites to emit a single radiation beam that concentrates power in a singular direction. Due to the curvature of the Earth, the electromagnetic waves radiated by the antenna array travel different distances. Waves traveling in the satellite’s nadir direction cover a shorter distance compared to those propagating in more distant directions. This phenomenon causes power losses at the edges of the coverage area. To compensate for these losses, the use of Isoflux radiation antenna arrays is proposed. These arrays distribute the power density evenly across the coverage area, increasing gain in directions where the path is longer. Achieving such radiation characteristics becomes more difficult for low-Earth orbit satellites. Due to the satellite’s proximity to Earth, radiation needs to extend over a large portion of the elevation plane, requiring an Isoflux beam that exceeds 100 degrees. This thesis presents 18 antenna array designs for satellites at the orbital altitudes of 340 km, 550 km, and 1150 km. Linear, planar, and concentric ring geometries are employed, with both periodic and aperiodic antenna element distributions. The distribution of amplitude excitations and the spacing between antenna elements are optimized using genetic algorithms. This thesis includes a comparative analysis of the radiation performance and the number of elements of the presented designs, categorized by orbital altitude.

arreglos de antenas, radiación Isoflux, satélites LEO, algoritmos genéticos antenna arrays, Isoflux radiation, LEO satellites, genetic algorithms INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA ELECTRÓNICA ANTENAS ANTENAS

Assessing the Spatiotemporal Relationship between Coastal Habitats and Fish Assemblages at Two Neotropical Estuaries of the Mexican Pacific

VICTOR MANUEL MURO TORRES FELIPE AMEZCUA MARTINEZ Gerogina Ramírez Ortiz FRANCISCO JAVIER FLORES DE SANTIAGO Felipe Amezcua Linares Yareli Hernández Álvarez (2022, [Artículo])

"Differences in fish assemblages’ structures and their relations with environmental variables (due to the variations in sampled seasons, habitats, and zones) were analyzed in two adjacent estuaries on the north Pacific coast of Mexico. Environmental variables and fish catches were registered monthly between August 2018 and October 2020. Multivariate analyses were conducted to define habitats and zones based on their environmental characteristics, and the effect of this variability on fish assemblages’ composition, biomass, and diversity (α and β) was evaluated. A total of 12,008 fish individuals of 143 species were collected using different fishing nets. Multivariate analyses indicated that fish assemblages’ structures were different between zones due to the presence, height, and coverage of distinct mangrove species. Additionally, depth and salinity showed effects on fish assemblages’ diversity (α and β-nestedness), which presented higher values in the ocean and remained similar in the rest of the analyzed zones and habitats. These results and the differences in species replacement (β-turnover) indicate the singularity of fish assemblages at estuaries (even in areas close to the ocean) and the necessity to establish local management strategies for these ecosystems."

mangrove forests, marine protected areas, alpha diversity, beta diversity, multivariate analyses CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS PECES Y FAUNA SILVESTRE DINÁMICA DE LAS POBLACIONES DINÁMICA DE LAS POBLACIONES

Enhancement of antibiotics antimicrobial activity due to the silver nanoparticles impact on the cell membrane

Roberto Vazquez-Munoz (2019, [Artículo])

The ability of microorganisms to generate resistance outcompetes with the generation of new and efficient antibiotics; therefore, it is critical to develop novel antibiotic agents and treatments to control bacterial infections. An alternative to this worldwide problem is the use of nanomaterials with antimicrobial properties. Silver nanoparticles (AgNPs) have been extensively studied due to their antimicrobial effect in different organisms. In this work, the synergistic antimicrobial effect of AgNPs and conventional antibiotics was assessed in Gram-positive and Gram-negative bacteria. AgNPs minimal inhibitory concentration was 10–12 μg mL-1 in all bacterial strains tested, regardless of their different susceptibility against antibiotics. Interestingly, a synergistic antimicrobial effect was observed when combining AgNPs and kanamycin according to the fractional inhibitory concentration index, FICI: <0.5), an additive effect by combining AgNPs and chloramphenicol (FICI: 0.5 to 1), whereas no effect was found with AgNPs and β-lactam antibiotics combinations. Flow cytometry and TEM analysis showed that sublethal concentrations of AgNPs (6–7 μg mL-1) altered the bacterial membrane potential and caused ultrastructural damage, increasing the cell membrane permeability. No chemical interactions between AgNPs and antibiotics were detected. We propose an experimental supported mechanism of action by which combinatorial effect of antimicrobials drives synergy depending on their specific target, facilitated by membrane alterations generated by AgNPs. Our results provide a deeper understanding about the synergistic mechanism of AgNPs and antibiotics, aiming to combat antimicrobial infections efficiently, especially those by multi-drug resistant microorganisms, in order to mitigate the current crisis due to antibiotic resistance. © 2019 Vazquez-Muñoz et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

ampicillin, antibiotic agent, aztreonam, beta lactam antibiotic, biapenem, chloramphenicol, kanamycin, silver nanoparticle, silver nitrate, antiinfective agent, metal nanoparticle, silver, antibiotic sensitivity, antimicrobial activity, Article, bact BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOFÍSICA BIOFÍSICA