Significado de la independencia de Centroamérica en su Bicentenario 1821-2021

La independencia de Centro América como se ha venido expresando en estos 200 años tuvo que ver sin lugar alguno con fenómenos externos e internos, en el primer caso la independencia de las 13 colonias de Norteamérica en 1776, la ilustración finales del SXVIII, la revolución francesa 1789, la invasión de Napoleón Bonaparte en 1808 y las Reformas Borbónicas provocó el mayor vacío de la historia del poder real, la destitución de Fernando VII fue el caldo necesario para que las colonias españolas en América y el Caribe provocaran la estampida de los funcionarios reales y que por efecto se autoproclamaran las independencias por todos los vastos territorios anteriormente gobernados con el yudo real

El derribamiento del avión CK123 donde venía E. Hassenfus y el triunfo contundente de Nicaragua en la Haya: pasos para consolidar la segunda independencia

Desde que se produjo el triunfo de la RPS el 19 de Julio de 1979, EE-UU se empeñó en destruirla debido al efecto inmediato que provocó en la región, un ejemplo que marcó las posibilidades para que los pueblos de Centroamérica y del Caribe se dieran cuenta que las dictaduras marionetas del norte, no eran tan imbatibles como se nos había dicho. El interés de los EE-UU fue tan marcado que distorsionó, manipuló a la población y creo la guerra de baja intensidad para ahogar a nuestra revolución destruyendo todo avance en el campo económico, social y político

Towards generalized measures grasping CA dynamics

In this paper we conceive Lyapunov exponents, measuring the rate of separation between two initially close configurations, and Jacobians, expressing the sensitivity of a CA's transition function to its inputs, for cellular automata (CA) based upon irregular tessellations of the n-dimensional Euclidean space. Further, we establish a relationship between both that enables us to derive a mean-field approximation of the upper bound of an irregular CA's maximum Lyapunov exponent. The soundness and usability of these measures is illustrated for a family of 2-state irregular totalistic CA

Efficiency Maximization of a Jet Pump for an Hydraulic Artificial Lift System

In science and engineering, mathematical modeling serves as a tool to understand processes and systems acting as a testing bed for several hypotheses. The selection of a specific model, as well as its variables and parameters, depends on the nature of the system under analysis and the acceptable simplifying assumptions. Therefore, it must allow for a good fit between both the hypothesis and the available data. Opposite to other design approaches based on experimental data or/and complex models, this work presents a simpler numerical design method for efficiency maximization of an Hydraulic Jet Pump (HJP) for oil-well extraction process, considering its hydraulic and geometric parameters. The design process consists in setting and solving a constrained non-linear optimization problem by taking into account the hydraulic model of the HJP in terms four design variables: throat area, nozzle area, injection flow, and injection pressure to the oil-well. The objective function of this case aims to maximize the HJP's efficiency avoiding to approach cavitation condition as well fulfilling technical constraints. A numerical technique, Differential Evolution Algorithm (DEA), has been implemented to solve the optimization problem. The proposed methodology leads to a solution set by considering only commercial geometries and feasible operating conditions for the HJP, which facilitates its practical implementation. A set of ten oil-wells with land production data, operating in the southeaster of Mexico, is used to compare and validate several Jet pump designs, i. e., through comparison with actual oil-well's operation condition.Peer Reviewe

Pure and doped boron nitride nanotubes

"More than ten years ago, it was suggested theoretically that boron nitride (BN) nanotubes could be produced. Soon after, various reports on their synthesis appeared and a new area of nanotube science was born. This review aims to cover the latest advances related to the synthesis of BN nanotubes. We show that these tubes can now be produced in larger amounts and, in particular, that the chemistry of BN tubes appears to be very important to the production of reinforced composites with insulating characteristics. From the theoretical standpoint, we also show that (BN)-C heteronanotubes could have important implications for nanoelectronics. We believe that BN nanotubes (pure and doped) could be used in the fabrication of novel devices in which pure carbon nanotubes do not perform very efficiently.

Uso potencial de subproductos biorrefinados de Moringa oleifera en la alimentación de codornices japonesas

  With the aim of evaluating the degreased paste from seed pressing (SMOD) and a residue flour from leaves fermented by Mucor circinelloides-Saccharomyces cerevisiae (HMHF), biorefining byproducts from the processes of biodiesel and bioethanol production from Moringa oleifera (MO), the effect of their inclusion was tested in fattening Japanese quails, measuring productive response parameters and carcass yields. The results were compared to diets containing unfermented MO leaf (HMNT) and a conventional one (TEST). For this purpose, 180 quails were fed during 35 days with the formulated diets. The diet with HMNT showed the lowest weight gain and the highest mortality. SMOD obtained the highest average of final live weight, weight gain and the lowest food conversion. SMOD presented the highest weights and HMNT the highest percentages of warm and cold carcass. It is concluded that the degreased pastes from seed pressing and the flour from fermented MO can be used at the inclusion levels tested in diets to feed Japanese quails, without negative effects on their growth.  Con el fin de evaluar la pasta desgrasada por prensado de semilla (SMOD) y una harina de residuo de hojas fermentadas por Mucor circinelloides-Saccharomyces cerevisiae (HMHF), subproductos biorrefinados de los procesos de producción de biodiesel y bioetanol a partir de Moringa oleifera (MO), se probó el efecto de su inclusión en dietas de iniciación y finalización para codornices japonesas, midiéndose parámetros de desarrollo y rendimientos de canal. Los resultados se compararon con dietas conteniendo hoja de MO no fermentada (HMNT) y una convencional (TEST). Para ello, se alimentaron 180 codornices durante 35 días con las dietas formuladas. Durante la etapa de iniciación la dieta con HMNT mostró la menor ganancia de peso y la mayor mortalidad. SMOD obtuvo el mayor promedio de peso vivo final, ganancia de peso y menor conversión alimenticia. SMOD presentó los pesos más altos y HMNT los mayores porcentajes de canal caliente y fría. Se concluye que las pastas de semilla desgrasada por prensado y la harina de hoja fermentada de MO pueden usarse a los niveles de inclusión probados, en dietas para alimentar codornices japonesas sin efectos negativos en su crecimiento

Handmade fish meal as a partial replacement of soybean meal in diets for feedlot lambs: Effects on growth performance, dietary energy and meat quality

With the aim to evaluate a handmade fishmeal (HFM) as a partial replacement of soybean meal (SBM) in finishing diets, 36 intact male Dorper × Pelibuey lambs (41.43±7.38 kg of initial weight) were used in a completely randomized block design to test the following treatments: 1) Cracked corn-based diet containing 12% SBM, 2) inclusion of 3.5% of HFM partially replacing SBM, and 3) inclusion of 7% of HFM partially replacing SBM. Urea and limestone were utilized to balance diets in CP and calcium content. The feeding trial lasted 30 days. Replacement of SBM with HFM did not modify the effects on average daily gain (ADG) and dry matter intake (DMI), but there were numerical differences in ADG; HFM inclusion linearly improved gain-to-feed ratio; dietary net energy (NE) and observed-to-expected diet NE. Hot carcass weight and dressing percentage were not affected by HFM. Except a linear increase on C22:6, the effect of SBM replacement on fatty acid profile in meat was not significant. The meat pH registered at 24 h post-mortem linearly increased with HFM inclusion, but meat colour and sensorial values were unaffected. It was concluded that inclusion of up to 7% of HFM in diet as partial replacement of soybean meal did not negatively affect DMI and ADG, but can increase feed efficiency and dietary energy utilization. The effects of HFM on carcass and meat quality were inappreciable. Due to variations in handmade processing, it is important to verify its chemical composition before HFM can be incorporated into diets

Extraordinary room-temperature photoluminescence in WS2 monolayers

Individual monolayers of metal dichalcogenides are atomically thin two-dimensional crystals with attractive physical properties different from their bulk layered counterpart. Here we describe the direct synthesis of WS2 monolayers with triangular morphologies and strong room-temperature photoluminescence (PL). Bulk WS2 does not present PL due to its indirect band gap nature. The edges of these monolayers exhibit PL signals with extraordinary intensity, around 25 times stronger than the platelets center. The structure and composition of the platelet edges appear to be critical for the PL enhancement effect. Electron diffraction revealed that platelets present zigzag edges, while first-principles calculations indicate that sulfur-rich zigzag WS2 edges possess metallic edge states, which might tailor the optical response reported here. These novel 2D nanoscale light sources could find diverse applications including the fabrication of flexible/transparent/low-energy optoelectronic devices

A Multiproxy Database of Western North American Holocene Paleoclimate Records

Holocene climate reconstructions are useful for understanding the diverse features and spatial heterogeneity of past and future climate change. Here we present a database of western North American Holocene paleoclimate records. The database gathers paleoclimate time series from 184 terrestrial and marine sites, including 381 individual proxy records. The records span at least 4000 of the last 12 000 years (median duration of 10 725 years) and have been screened for resolution, chronologic control, and climate sensitivity. Records were included that reflect temperature, hydroclimate, or circulation features. The database is shared in the machine readable Linked Paleo Data (LiPD) format and includes geochronologic data for generating site-level time-uncertain ensembles. This publicly accessible and curated collection of proxy paleoclimate records will have wide research applications, including, for example, investigations of the primary features of ocean-atmospheric circulation along the eastern margin of the North Pacific and the latitudinal response of climate to orbital changes. The database is available for download at https://doi.org/10.6084/m9.figshare.12863843.v1 (Routson and McKay, 2020)