bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical modeling of Etla Valley aquifer, Oax., Mexico: Evolution and remediation scenarios
Authors: Flores-Márquez E. L. , Martínez-Serrano R. G. , Chávez R. E. , Crusillo Y. , Jiménez G. , Campos-Enriquez O.
Published: April 2021

Se presenta un modelo geohidrológico evolutivo 3D a corto plazo (para los años 2001, 2005 y 2015) del acuífero somero del Valle de Etla, Oaxaca, sureste de México, basado en los parámetros disponibles de geología, geofísica, geoquímica e hidrología. Las simulaciones numéricas fueron realizadas en Visual MODFLOW. Estas simulaciones indican que, si el actual régimen de extracción es mantenido, el abatimiento de la superficie potenciométrica puede ser mayor en el SE del área de estudio (i. e. cerca de la ciudad de Oaxaca). La contaminación por fertilizantes y por las fugas de drenaje es favorecida por la dirección de flujo imperante en el acuífero (vaciándose en el río Atoyac) De acuerdo a las simulaciones numéricas, existe una posible remediación de este proceso, relocalizando los pozos situados en la ciudad de Oaxaca en las zonas de recarga (i. e. en las faldas de la Sierra de Juárez). Este escenario de remediación permitiría una recuperación en el nivel de la superficie potenciométrica.
Computational platform of the Mexican Virtual Solar Observatory
Authors: Hernández-Cervantes L. , González-Ponce A. , Santillán A.
Published: April 2021

El Observatorio Virtual Solar Mexicano (MVSO, por sus siglas en inglés) es un proyecto en desarrollo, cuyo objetivo es generar una base de datos producida por simulaciones numéricas asociadas a fenómenos solares. En este trabajo hacemos una descripción de la plataforma computacional del OVSM y explicamos más en detalle el desarrollo de la interfaz gráfica para hacer las simulaciones numéricas remotas, la generación de la base de datos y las herramientas de búsqueda.
XFTRISTAN: A program to visualize the interaction between solar wind and Earth’s magnetosphere
Authors: Blanco-Benavides J. M. , Frutos-Alfaro F.
Published: April 2021

XFTRISTAN es una interfaz gráfica para el programa TRISTAN, un código basado en el método PIC (particle in cell) tridimensional. Este código ha sido ampliamente usado para investigar la naturaleza cinética de los procesos de plasmas espaciales que van desde aplicaciones relacionadas con la interacción de viento solar con la tierra hasta la topología de la reconexión magnética. La primera versión del XFTRISTAN provee un camino fácil para la introducción de parámetros de entrada, visualizaciones de campos y partículas, varias herramientas de diagnóstico y generación automática de imágenes. En este artículo presentamos las ventajas y virtudes de nuestra interfaz gráfica y los primeros resultados de las simulaciones.
Study of charge behavior during solar particle acceleration
Authors: Pérez-Peraza J. , Balderas-Aviles G. , Rodríguez-Frías D. , Del Peral L. , Hebrero G.
Published: April 2021

Con objeto de reproducir la evolución con energía de los estados de carga observacionales de los iones energéticos solares, hemos desarrollado un modelo en el que los estados de carga se definen en la fuente durante el proceso de aceleración de los iones solares. El intercambio de carga entre iones y la materia local se estudia en base a secciones eficaces de alta energía para pérdida y captura electrónica. El modelo se desarrolla bajo dos enfoques diferentes. Aplicamos el modelo a datos observacionales de estados de carga para la mayor parte los eventos publicados en la literatura. Analizamos y discutimos nuestros resultados e implicaciones dentro del contexto de otros modelos: concluimos que nuestro modelo analítico da mayor información de la física involucrada que las simulaciones numéricas desarrollada por otros autores.
Application of the pseudo-Thellier technique to a paleomagnetic record from lake El Trébol (Patagonia, Argentina)
Authors: G. Gogorza C. S. , Torcida S. , Sinito A. M. , E. Chaparro M. A.
Published: April 2021

The pseudo-Thellier technique was applied to obtain relative paleointensity determinations using a sediment core from Lake El Tre?bol (Patagonia, Argentina).

Measurements of intensity of natural remanent magnetization left (NRMleft) after AF demagnetization versus intensity of anhysteric remanent magnetization gained (ARMgained) at the same peak were carried out on a set of samples. Two versions of a jackknife resampling scheme were used to get error estimates on the paleointensity.

The pseudo-Thellier paleointensity records were compared with the authors previous results where the remanent magne- tization at 20mT (NRM20mT) has been normalized using the anhysteric remanent magnetization at 20mT (ARM20mT), the satu- ration of the isothermal remanent magnetization at 20mT (SIRM20mT) and the low field magnetic susceptibility (k) (Gogorza et al., 2006). The pseudo-Thellier record shows a reasonable agreement with the standard method of normalization (NRM20mT/ ARM20mT).
An exploratory study for rapid estimation of critical source parameters of great subduction-zone earthquakes in Mexico
Authors: Singh S. K. , Pérez Campos X. , Iglesias A. , Pacheco J. F.
Published: April 2021

The rapid and reliable estimation of moment magnitude Mw, location, and size of rupture area, and radiated energy Es of great Mexican subduction zone earthquakes is critical for a quick assessment of tsunami and/or damage potential of the event and for issuing an early tsunami alert. To accomplish this goal, the Mexican broadband seismic network needs to be supple- mented by permanent GPS stations along the Pacific coast, spaced about 65 km apart or less. The data from the GPS network must be transmitted to a central location and processed in near-real time to track the position of the stations. Assuming that this can be implemented, we develop a procedure for near-real time estimation of the critical source parameters. We dem- onstrate the viability of the procedure by processing near-source GPS data and regional seismograms for the earthquakes of Colima-Jalisco in 1995 (Mw=8.0) and Sumatra-Andaman in 2004 (Mw=9.0-9.3). The procedure yields estimates of Mw and Es in excellent agreement with those reported from earlier solutions. In the case of the Colima-Jalisco earthquake, the estimated location and size of rupture area agree with that mapped from aftershock locations. Presently, there are 13 permanent GPS stations along the Pacific coast of Mexico with an average spacing of ~200 km which operate in an autonomous mode. It is urgent to increase the number of stations to ?28 thus decreasing the spacing of stations to ?65 km. Data must be transmitted in near-real time to a central station to track the position of the stations, preferably every second.
CO2 flux from the volcanic lake of El Chichón (Mexico)
Authors: Mazot A. , Taran Y.
Published: April 2021

El flujo de dióxido de carbono fue medido en marzo de 2007 en la superficie del lago del Volcán El Chichón, México, usando el método de la cámara de acumulación flotante. Los resultados de 162 medidas y la aplicación del método estadístico estándar, desarrollado para estos estudios, demuestran que la tasa de emisión total de CO2 del lago cratérico es relativamente alta. La tasa de emisión total calculada con simulación secuencial Gaussiana fue de 164 Â± 9.5 t.d-1 para el área de superficie del lago de 138, 000 m2. Se proponen dos mecanismos diferentes de desgasificación (por difusión a través de la interfase agua-aire y por burbujas) después de usar el método estadístico gráfico (GSA). Los flujos más altos fueron observados a lo largo de trazas de fallas deducidas. Una desgasificación alta también fue observada a lo largo de lineamentos que concuerdan con fallas que afectan el basamento de la región. Si se considera que el flujo promedio de CO2 comprendiera todo el fondo del cráter (308,000 m2) se tendría una emisión total del cráter del Volcán El Chichón de por lo menos 370 t.d-1. Este flujo sería cinco veces más alto que el del lago volcánico de Kelud, Indonesia y similar al flujo de CO2 de otros volcanes activos con desgasificación pasiva en el mundo.
Non-methane Volatile Organic Compounds (VOCs) at El Chichón volcano (Chiapas, México): Geochemical features, origin and behavior
Authors: Tassi F. , Capaccioni B. , Capecchiacci F. , Vaselli O.
Published: April 2021

Se presenta un estudio de las características geoquímicas de la fracción orgánica en las fumarolas del volcán Chichón (Estado de Chiapas, México) para obtener información sobre el origen de los compuestos orgánicos volátiles exceptuando el metano (VOCs) y los procesos que rigen su comportamiento. Los VOCs en fumarolas y pozas burbujeantes consisten principalmente de alcanos (C2-C5) cuya abundancia total tiene un orden de magnitud menor que el metano, y concentraciones altas de aromáticos (benceno y tolueno) y C2-C3 alquenos (principalmente propano e iso-butano). Se encontraron también concentraciones significativas de compuestos de azufre substituidos que en su mayoría pertenecen al grupo de los heterocíclicos. Esta composición, similar a la de las emisiones gaseosas relacionadas a sistemas geotérmicos, sugiere que la producción de gases orgánicos en el volcán El Chichón es principalmente debida a procesos termogénicos. La abundancia total de VOCs es relativamente baja en comparación con la composición típica de fluidos hidrotermales, lo que podría estar relacionado a una contribución importante de fluidos de origen magmático al reservorio que alimenta las emisiones termales del cráter. Sin embargo, la ausencia de compuestos de O-substituidos parece indicar que la composición de los fluidos hidrotermales no es afectada por el aporte de especies orgánicas producidas en profundidades someras por la descomposición de material vegetal reciente, como aquél sepultado por los productos de la erupción de 1982.
El Chichón’s "surprise" eruption in 1982: Lessons for reducing volcano risk
Authors: Tilling R. I.
Published: April 2021

Durante una semana (marzo 28- abril 4, 1982), tres erupciones explosivas (VEI 5) del volcán El Chichón causaron el peor desastre volcánico en la historia de México. Flujos y oleadas piroclásticas arrasaron nueve poblados matando cerca de 2000 personas. La caída de ceniza provocó sufrimiento a miles de habitantes de los estados de Chiapas y Tabasco. La inesperada y vigorosa erupción del 28 de marzo causó una evacuación apresurada y confusa. La actividad disminuyó notablemente los cinco días siguientes, pero después ocurrieron las erupciones más poderosas y letales del 3 al 4 de abril; trágicamente las autoridades habían permitido el regreso a casa de muchos de los evacuados. Desafortunadamente las erupciones sorprendieron a los científicos y autoridades gubernamentales impidiendo la implementación oportuna de medidas de mitigación. Antes de la erupción, la actividad fumarólica y los sismos se incrementaron, por lo que los habitantes alrededor del volcán pidieron ayuda al gobierno de Chiapas y al gobierno Federal. La ayuda lenta, por parte de ambos gobiernos llegó después de la primera erupción. Probablemente la lección aprendida más importante fue que el científico a cargo y las autoridades militares que actuaron con su consejo, no tuvieron que haber considerado la disminución de la actividad (marzo 29 -abril 2) como una señal de que la erupción había terminado. A pesar de que las erupciones de 1982 causaron una tragedia nacional, también fomentaron estudios multidisciplinarios de los fenómenos eruptivos no sólo en el volcán El Chichón sino también de otros volcanes explosivos en el mundo.
A test of the effect of boundary conditions on the use of tracers in reservoir characterization
Authors: Coronado M. , Ramírez Sabag J. , Valdiviezo Mijangos O. , Somaruga C.
Published: April 2021

Tracer tests are fundamental in characterizing fluid flow in underground formations. However, the setting of appropriate boundary conditions in even simple analytical models has historically been controversial, mainly due to the lack of sufficient physical evidence. Determining the relevance of boundary conditions on tracer test analysis becomes therefore a topic of renewed interest. The subject has been previously disscused by studying the tracer breakthrough curve sensitivity to diverse model parameter values. In our present work we examine the issue from a new practical reservoir characterization perspective. Two well-known equivalent elementary tracer transport models having different boundary conditions are matched to the same tracer test data. The resulting model parameter difference quantifies the effect of boundary conditions on reservoir property determination. In our case a tracer pulse injected in a homogeneous one-dimensional porous medium and moving at constant speed dominated by advection and dispersion is considered. The tracer transport models to be used yield conditions (i) on the tracer concentration, and (ii) on the tracer flux. Three data sets from tracer tests performed in different oil reservoirs are used to fit the models and determine the parameter values. We found that boundary conditionsbecome more important as Peclet number gets smaller. The cases analyzed have Peclet numbers 25.0, 5.4 and 3.7. The largest parameter difference obtained in each case is 5%, 18% and 37% respectively. These differences are large for laboratory experiments, but less relevant for tracer tests in oil fields, where data variability is frequently high. Nevertheless, attention should be paid when small Peclet numbers are present.
Late Holocene tectonic land-level changes and tsunamis at Mitla lagoon, Guerrero, Mexico
Authors: Ramírez Herrera M. T. , Cundy A. B. , Kostoglodov V. , Ortíz M.
Published: April 2021

Sedimentological, stratigraphic and geochemical data record abrupt land elevation change, coastal subsid- ence, and changes in the salinity of Mitla lagoon that may be associated with a tsunami around 3400-3500 yr BP. The observations are supported by microfossil data (pollen, diatoms and phytolith) from other studies on the Guerrero coast. Stratigraphic data indicate an average Late Holocene sedimentation rate of about 1 mm/yr. Short-term sea-level records from 1952 of tide gauge data are compared with expected coseismic coastal deformation, and long-term records of coastal deformation from the sediment record c. 3500 yr BP. Recent large earthquakes in the Central Mexico subduction zone ruptured an area of limited width of about ~60 km, but some prehistoric earthquakes may have ruptured the entire coupled plate interface almost up to the trench, thus generating signifi- cant coastal subsidence and possibly a large tsunami.
Automatic non-volcanic tremor detection in the Mexican subduction zone
Authors: Husker A. , Peyrat S. , Shapiro N. , Kostoglodov V.
Published: April 2021

Desarrollo de un algoritmo de detección de tremores no-volcánicos (TNV). Un TNV ocurre en el rango de frecuencia de 1 - 10 Hz, pero el ruido ambiental alto ocurre por encima de los 2 Hz en muchas de las estaciones del MesoAmerican Seismic Experiment (MASE), entonces los sismogramas se filtran con un paso banda de 1 - 2 Hz. Se determina el efecto de sitio comparando la ventana de las codas de terremotos regionales en todas las estaciones, y luego se remueve. Se aplica un filtro mediano a la amplitud absoluta de los datos filtrados con el filtro de paso banda para remover los picos de los terremotos locales. Se quita la tendencia y el valor mediano de los archivos de datos de un día para eliminar el efecto de las tormentas y el ruido local. Se obtiene el promedio de todos los datos por día para amplificar la energía coherente de los TNV y para disminuir el ruido local. Se determina empíricamente un límite de amplitud de los TNV y se aplica a todos los datos diariamente del periodo de estudio para generar el catálogo de los TNV. Se compara el catálogo determinado automáticamente con el catálogo creado por el análisis visual de los espectrogramas diariamente. Se hace un análisis preciso durante el mes con la mayor diferencia entre los dos catálogos (mayo de 2006). Encontrandose que el algoritmo de detección automática tuvo menos falsos positivos y menos TNV indeterminados que la detección inicial de TNV visualmente, por lo tanto el algoritmo automático desarrollado de detección de TNV tiene menos errores y puede usarse efectivamente para futuros análisis de la actividad de los tremores.
Chicxulub crater post-impact hydrothermal activity - evidence from Paleocene carbonates in the Santa Elena borehole
Authors: Escobar-Sanchez J. E. , Urrutia-Fucugauchi J.
Published: April 2021

Los cráteres de impacto se caracterizan por sistemas hidrotermales activos; particularmente en aquellos formados en ambientes marinos, en los cuales los procesos convectivos incluyen fluidos hidrotermales y agua de mar. En este estudio se presentan resultados sobre la actividad hidrotermal en el cráter Chicxulub, formado por un impacto sobre la plataforma carbonatada en el sur del Golfo de México hace unos 65 Ma en el límite Cretácico/Terciario. Los sedimentos carbonatados post-impacto registran los efectos de actividad hidrotermal convectiva, lo cual nos permite investigar sobre las características y duración de estos procesos. En este artículo se presentan la geoquímica de elementos mayores y traza de los sedimentos carbonatados correspondientes a la secuencia basal del Paleoceno a una profundidad de 304 a 332 metros en los núcleos del pozo Santa Elena, localizado al sur del borde de la cuenca principal del cráter Chicxulub. La geoquímica de elementos mayores y traza registra evidencias de actividad hidrotermal, marcada por un enriquecimiento en los primeros 10 metros de la secuencia sobre el contacto con las brechas de impacto. Las calizas presentan concentraciones altas de sílice, magnesio, aluminio, potasio y fierro, observándose patrones de variaciones similares en otros óxidos, así como en los elementos traza. El enriquecimiento concuerda con modelos de variación asociados a un aporte hidrotermal mejor que con otros posibles procesos asociados como podrían ser efectos diagenéticos o contribuciones detríticas procedentes de otras fuentes. El contenido relativo de los óxidos mayores en los primeros 12 metros de la sección (desde los 332 hasta los 322 metros), presenta 50 % de CaO y alrededor del 2% de SiO2 y MgO; patrones similares se observan para los otros óxidos, así como para los elementos traza. Considerando que la posición del sitio de estudio, se encuentra cercana a la zona central, las anomalías geoquímicas, presentan una elevada actividad convectiva provocada por la brecha de impacto subyacente a esta secuencia, y el aporte asociado con las fuentes hidrotermales distales del área central. Las concentraciones de Fe, K y Al corresponden con un aporte hidrotermal, también observado en los elementos traza (Zn, V, Cr, Ni, Cu, Zr y Rb). Después del cese de la actividad mayor hidrotermal, aproximadamente enseguida de 1 Ma posterior al impacto, actividad intermitente hidrotermal posiblemente continuó operando por un periodo mayor.
Unified formulation of enhanced oil-recovery methods
Authors: Herrera Ismael , Herrera Graciela S.
Published: April 2021

En la actualidad las técnicas de recuperación mejo-rada de petróleo (EOR, por sus siglas en inglés) son esenciales para mantener los suministros de petróleo del mundo. A su vez, los modelos matemáticos y computacionales de los métodos EOR son fundamentales para su aplicación y per-feccionamiento. Debido a la gran diversidad de procesos que ocurren en la EOR, es valioso contar con procedimientos generales unificados para la construcción de los mismos, que puedan aplicarse fácilmente independientemente de la complejidad del sistema considerado. El objetivo de este trabajo es presentar un modelo matemático unificado, que incluya ambos: el sistema gobernante de las ecuaciones en derivadas parciales y las condiciones de choque. Éste se basa en una formulación axiomática, pues las formulaciones axiomáticas son el medio más eficaz para lograr generalidad, sencillez y claridad. En el enfoque que se propone aquí, la construcción del modelo matemático es en gran medida automática, todo lo que se requiere a fin de definir las ecuaciones en derivadas parciales y las condiciones de choque que constituyen un modelo básico consiste en identificar las fases y las propiedades extensivas que participan en el sistema de la EOR. Este modelo básico proporciona una base muy firme para incorporar la fenomenología. El procedimiento se ilustra derivando los modelos matemáticos más utilizados en la tecnología EOR; en particular, se derivan los modelos de petróleo negro y los composicionales, tanto en su versión isotérmica como sus variantes térmicas, en las cuales es indispensable incluir el balance de energía. Para ilustrar la aplicación de la formulación axiomática a modelos con discontinuidades, se realiza también una descripción exhaustiva de los choques que pueden ocurrir en el Modelo de Petróleo Negro.
Evidence for Precambrian faulting in the TibatiÂ­Adamawa region of Cameroon using the audiomagnetotelluric method
Authors: Manga Ngando Akoumou , Nouayou Robert , Tabod Tabod Charles , Manguelle-Dicoum Eliezer
Published: April 2021

La falla de Adamawa es una estructura tectónica relacionada con la línea volcánica de Camerún. Se han obtenido datos ATM a lo largo de una superficie de case 1,600 kmÂ² alrededor de la ciudad de Tibati. El conocimiento geológico del área es escaso; los últimos datos se recopilaron hace 50 años. Este artículo describe las etapas principales, seguidas de la determinación de la firma electromagnética de la falla. Los resultados muestran numerosas zonas anómalas atribuidas a la zona de Cizalla. Todo ello nos permiten inferir la estructura de la resistencia eléctrica y hacen posible tener conocimiento acerca de la falla Tibali. Estos resultados son preliminares a un estudio de la estructura de esta falla precámbrica. En este estudio se produjeron valores y variaciones importantes de la aparente resistencia. La falla de Tibali se caracteriza por su gran complejidad y estrechez.
A source study of the October, 2007 earthquake sequence of Morelia, Mexico
Authors: Singh Shri Krishna , Iglesias Arturo , Quintanar Luis , Garduño Victor Hugo , Ordaz Mario
Published: April 2021

En este artículo se analiza una secuencia de siete sismos (2.5<Mw<3.0) ocurridos en la Ciudad de Morelia, México. Esta serie de temblores ocurrieron en un intervalo de 33 horas en el mes de octubre de 2007. Fueron registrados por dos estaciones locales ubicadas en esa Ciudad. Morelia se encuentra en la la parte central de la Faja Volcánica Trans-Mexicana (CTMVB, por sus siglas en inglés). Las formas de onda y los espectros de estos sismos son sorprendentemente similares, sugiriendo que sus localizaciones y mecanismos focales son casi idénticos. La inversión de forma de onda, restringida a partir de fallas descritas anteriormente en el área (rumbo ~E-O, buzando al norte), arroja un mecanismo focal definido por , y , lo cual es consistente con los mecanismos focales reportados previamente en la región. Dado que, para estos pequeños eventos, la señal se confunde con el ruido para frecuencias f<0.2Hz, se estimó el momento sísmico a partir del espectro de las ondas S en una banda de frecuencias definida en el intervalo 0.2â‰¤fâ‰¤1Hz. Sin embargo, en esta banda de frecuencias, existe una amplificación significativa de las ondas símicas debida a una capa de baja velocidad provocada por rocas volcánicas superficiales presentes en cualquier sitio localizado en el CTMVB. En la estimación del y en la interpretación de los espectros observados, se aproximó esta amplificación usando el cociente espectral H/Z. Asumiendo un modelo de fuente , los espectros observados pueden ser explicados con ternas (Î”Ïƒ, t*, ) (5MPa, 0.02s, 20Hz) y (20 MPa, 0.03 s, 20 Hz), donde Î”Ïƒ es la caída de esfuerzos asumiendo el modelo de Brune y t* y .son los parámetros de atenuación. Con el fin de simular el movimiento fuerte del terreno, para un sismo postulado de , se usaron estas combinaciones de parámetros junto con las técnicas de Empirical Green Function (EGF) y Random Vibration Theory (RVT). Las aceleraciones horizontales PGA y velocidades PGV en los sitios de referencia están en el rango de 23 a 46 cm/ y de 1.5 a 3.52 cm/s para una caída de esfuerzos de Î”Ïƒ=5Mpa. Los valores pronosticados para una caída de esfuerzos Î”Ïƒ=20Mpa son casi el doble (44-89 cm/ and 2.5-6.1 cm/s). Las estimaciones obtenidas, especialmente para Î”Ïƒ=5MPa, son considerablemente más pequeñas que las reportadas a partir de datos globales. Esta comparación sugiere que existe una alta atenuación en la región volcánica o una inadecuada estimación del efecto de t* y .
Environmental Issues in Recent British and Canadian Elections
Authors: Clarke Harold D. , Pammett Jon H.
Published: April 2021

ENVIRONMENTAL ISSUES IN RECENT BRITISH AND CANADIAN ELECTIONS

 

            The 2019 elections in Britain and Canada illustrate the difficulties in communication between a concerned public and prospective office-holders on the most critical set of issues of our times.  An increased level of public awareness and concern about the state of the environment has been expressed in public opinion polls, social movement activity has increased, and Green parties have expanded their appeal.  Despite these developments in recent years, environmental issues have not been able to exert a major impact on individual voting behaviour in elections, or on overall election outcomes.  Issues related to the environment are usually treated, by both politicians and the public, in valence terms.  Valence issues are ones upon which there is broad consensus about the goals of public policy, and political debate focuses not on "what to accomplish" but rather on "how to do it" and "who is best able."  Regarding the environment, general formulations like global warming and climate change prompt politicians to offer concerned rhetoric and engage in virtue signaling, but specific policy proposals are often absent.    

            This paper examines four reasons why environmental/climate change issues did not have a major impact on the 2019 Canadian and British elections. First, environmental concern in society at large was imperfectly translated into election issues.  Second, the major political parties produced inadequate and unconvincing environmental manifestos.  Third, environmental issues were not central to most voting decisions. Fourth, environmental issues had limited impacts on election outcomes.
Carbon storage in cocoa growing systems across different agroecological zones in Ghana
Authors: Afele John Tennyson , Dawoe Evans , Abunyewa Akwasi Adutwum , Afari-Sefa Victor , Asare Richard
Published: April 2021

Shade grown cocoa systems have been credited with stocking high quantities of carbon and therefore possess the potential to mitigate climate change and help achieve targets of the United Nations Collaborative Program on Reduced Emissions from Deforestation and Forest Degradation (REDD+). This study quantifies and compares carbon stored as well as estimated cocoa yields in two shade management types (i.e., shaded and full sun) across three agroecological zones: Dry Semi-Deciduous Fire Zone (DSFZ), Moist Evergreen Zone (MEZ) and Upland Evergreen Moist Zone (UEMZ) in Ghana.  Results show that Soil organic carbon (SOC) stored decreased with increasing soil depth across all agroecological zones. Cocoa farms with shade trees stored 6 times more soil carbon (35.90±1.56 Mg C ha-1) compared to the full sun systems (5.98±1.56 Mg C ha-1). Carbon stocks in the DSFZ and the MEZ were 61.73±1.02 Mg C/ha and 67.46±1.02 Mg C ha-1 respectively whiles the UEMZ recorded 85.10 Mg C ha-1. Across agroecological zones, pod count in the UEMZ and the MEZ were similar but varied from that of the DSFZ, which recorded the least. Wilting of pods and cherrelles, was minimal and similar in the UMEZ and the MEZ but was significantly higher in the DSFZ. It is recommended that farmers should be encouraged through strong policies to adopt the integration of shade trees in the production of cocoa in Ghana to mitigate the effects of climate change.
Technological characterization of a clay used in the manufacture of masonry products for construction
Authors: Crespo-Guerra María Teresa , García-León Ricardo Andrés , Afanador-García Nelson
Published: April 2021

In the present investigation, the physical, mechanical, and chemical characterization of the raw material used in two companies dedicated to the manufacture of solid bricks in the region of Cesar, Colombia, was carried out. Initially, the hydrometric test was performed on five clay samples from different quarries with which the percentages of sand, silt, and clays were determined. These percentages were placed in the Winkler diagram to identify the types of existing clays according to their texture and the types of products that can be manufactured. Subsequently, the chemical characterization was carried out through the X-ray diffraction and fluorescence tests, to determine the phases and elements present in two of the optimal samples for the manufacture of the bricks that may arise during the cooking process. The results of the test of mechanical resistance to compression in solid brick units showed that the clays currently used by the company do not meet the minimum requirements for the production of solid clay bricks, according to the parameters of the Colombian technical standard NTC 4205-09. With this research, we expect to predict the behavior of the raw material in the stages of the production process, which will obviously improve the environmental and economic resources of the companies. The result of the characterization of the raw material will allow us to predict the structural behavior and to carry out indispensable design and reinforcement models in building and attention to the community.
Calibration and standardization of air quality measurements using MQ sensors
Authors: Carrillo-Amado Yersson Ramiro , Califa-Urquiza Miguel Angel , Ramón-Valencia Jacipt Alexander
Published: April 2021

To perform the calibration and standardization of the air quality measurements through the MQ sensors, a mathematical relation was used based on the information provided by the manufacturers of the sensors through their data sheets, using the linear mathematical regression model that allowed to create the libraries for the sensors MQ-2, MQ-3, MQ-4, MQ-5, MQ-6, MQ-7, MQ-8, MQ-9, MQ-135, MQ-131, MQ-303A, MQ-309A, These libraries are characterized by being open source, and are available to the public, whose software tool allows to take values in parts per million (ppm) from the value of the resistance read in the sensor, allows to obtain data which are similar to other scientific studies given that they give in the same units, which serve to perform studies in the environment, pollution, analysis in industrial processes.
Optimización de costos en la empresa TCC S.A
Authors: Contreras-Cáceres Marynelda , Martínez-Álvarez. Giovanni Alexánder , Torres-Gómez Freddy , Marulanda-Ascanio Carolina
Published: April 2021

El presente trabajo tiene como propósito crear una propuesta de mejoramiento para aminorar los gastos representados por conceptos de horas extra y recargos en la empresa TCC. De igual manera, se pretende hacer un diagnóstico que permita la identificación del origen del problema junto con un análisis detallado de las cuentas de gastos del personal por dicho concepto. Utilizando datos de información primaria suministrados por la empresa, encontrando retrasos de la llegada de los vehículos de carga Nacional por motivos ajenos a la empresa, retrasos que generan un tiempo muerto que finaliza en sobrecostos.  Frente a esto se plantea implementar un nuevo diseño que evité el retraso de envíos y así eliminar o disminuir al máximo estos tiempos muertos para agilizar el procedimiento y disminuir el tiempo adicional que se usa para esto.
Anatomical traits of Artemisia umbelliformis subsp. eriantha (asteraceae) alpine glacial relict from Mt. Durmitor (Montenegro)
Authors: Janackovic Pedja , Gavrilovic Milan , Rancic Dragana , Stesevic Danijela , Dajic-Stevanovic Zora , Marin Petar
Published: April 2021

In this study, the vegetative anatomy of Artemisia umbelliformis subsp.
eriantha, a Central European alpine glacial relict, wild-growing on Mt.
Durmitor (Montenegro) was examined for the first time. The aim was to
investigate the general anatomy and particular anatomical traits which might
have possible taxonomic value. Microscopic slides were prepared according to
the standard histological procedures. The adventitious young root showed a
primary structure, while the older root showed a secondary structure with a
well-developed periderm on its surface. The rhizome showed a primary
structure with elements of a secondary structure (periderm). The stem cross
section is characterized by a round shape with a well-developed periderm at
certain stages, and collateral vascular bundles arranged in a circle. The
petiole is concave in shape with a single-layered epidermis and parenchyma
tissue with one large and two small vascular bundles. Druses and
rhombohedral crystals are observed inside some petiole parenchyma cells. The
leaf lobe cross section has an oblong-linear shape and is isolateral and
amphistomatous in structure. The anticlinal walls of the leaf epidermal
cells are sinuate. Secretory canals are present in the root cortex
parenchyma (endodermal secretory canals) and the rhizome cortical
parenchyma. The stem, petiole and leaf lack secretory canals. The stem and
leaf are covered with T-shaped non-glandular and glandular trichomes. The
taxonomic value of the analyzed characteristics is briefly discussed.
Differences in proline accumulation between wheat varieties in response to heat stress
Authors: Djukic Nevena , Markovic Stefan , Mastilovic Jasna , Simovic Predrag
Published: April 2021

Proline is one of the organic osmolytes that accumulates in plants in
response to stressful environmental conditions. The aim of this study was to
determine the concentration of proline in the grain filling phase in ten
winter wheat cultivars under conditions of prolonged periods of air
temperatures above 30?C and to assess the variability of wheat variety
responses. The correlation between proline accumulation and photosynthetic
pigments, accumulated starch and yield was also determined. In the
experimental field, flag leaves were sampled for each variety in the grain
filling phase. Statistical data analysis and parameter correlation were
performed using the SPSS program. The results showed that there is a
statistically significant difference between proline values in moderate and
high air temperature conditions when proline accumulation occurs. The
significant correlation of accumulated starch content and yield with proline
concentration showed that in addition to higher proline values under heat
stress, wheat varieties Apac, Talas and Futura also have higher yield and
starch content. A correlation was also found between proline concentration
and photosynthetic pigment contents, where the Apac wheat variety showed the
best adaptive response to the investigated traits and was characterized by a
smaller reduction in photosynthetic pigment content under heat stress. The
interrelation of proline with the photosynthetic pigment content and wheat
quality parameters may be important in breeding technologies aimed at
improving wheat stress tolerance.
Prediction of Optimum Weld Tensile Strength Using Response Surface Methodology
Authors: Etin-Osa C. E. , Ebhota L. M.
Published: April 2021

Metals are often subjected to various types of stresses, usually under tensile stress, quick failure of material can be encouraged especially when poor combinations of process parameters are employed in joining of the material. Tensile strength is regarded as the maximum stress that a material can sustain under tension. The aim of this study is to predict the weld tensile strength of tungsten inert gas (TIG) mild steel welds using Response Surface Methodology (RSM), with the purpose of achieving optimum results.

The input parameters considered were current, voltage, and gas flow rate. The TIG welding process was used to join two pieces of mild steel plates, after which tensile test was conducted on the specimen. The experimental result was analyzed using the RSM.

Weld Tensile test of 596.218MPa with a desirability value of 95.70% was observed to be the best, resulting from the optimized process parameters of current of 120.00 Amp, voltage of 20.00 volt and gas flow rate of 12.00 L/min.
Evaluation of the Influence of the Level of Corrosion of the Reinforcing Steel in the Moment-Curvature Diagrams of Rectangular Concrete Columns
Authors: Landa-Ruiz Laura , Croche René , Santiago-Hurtado Griselda , Moreno-Landeros Victor , Cuevas Josefina , Méndez Ce Tochtli , Jara-Díaz Manuel , Baltazar-Zamora Miguel Angel
Published: April 2021

In the present work, it is proposed to include in the theoretical curves of moment-curvature (m- φ) the effect of corrosion by obtaining the decrease in the area of longitudinal reinforcing steel. The corrosion depth will be obtained from the crack width and corrosion length observed in the cover concrete. With the depth of corrosion, the area of steel that is lost will be obtained and this modification will be incorporated into the theoretical procedure to elaborate the m- φ curves. The forces of the steel will be obtained from an elastoplastic model with curved hardening and the forces of the concrete with a model that considers the effect of confinement.
RELAÇÃO SAÚDE-DOENÇA A PARTIR DAS EXPERIÊNCIAS DE VIDA DAS CRIANÇAS
Authors: Bezerra Beltrão Glenda Gabriele , De Souza Aguiar José Vicente , Mota da Silva Andrigéssica
Published: April 2021

Discussões sobre educação em saúde são urgentes e devem abranger tanto escolas quanto espaços não-escolares, a fim de que as crianças possam ter reflexões essenciais acerca de assuntos que influenciam na sua vida e, consequentemente, na sua saúde. Buscou-se compreender como a temática saúde-doença se relaciona às experiências de vida das crianças do 5º ano do Ensino Fundamental de uma escola estadual da cidade de Barreirinha, Amazonas. A pesquisa foi desenvolvida com abordagem e análise de dados de cunho fenomenológico-hermenêutico. A investigação contou com 16 crianças de ambos os sexos, com idade entre dez e onze anos, de uma turma 5º ano do Ensino Fundamental. Os resultados apontam que as crianças têm conhecimentos da temática saúde-doença e apresentam uma pluralidade de experiências cotidianas de adoecimento (experiências de adoecimento, relacionamento interpessoal, lazer, hábitos de higiene e alimentar) que podem afetar suas vidas e seus desempenhos escolares. Em relação às questões alimentares, contudo, há uma dissociação, em parte, entre o saber adquirido nas aprendizagens escolares e as atitudes de escolhas alimentares, dentre as possíveis por elas. Esta dissociação indica a necessidade de buscar meios que não só contribuam para a aquisição de conhecimentos teóricos, mas que possibilitem aos alunos fazerem articulação no seu cotidiano, principalmente nas escolhas alimentares, sobretudo daqueles menos prejudiciais à saúde. Esse trabalho destaca a necessidade de discussões sobre o tema saúde-doença nos espaços escolares e não-escolares, de maneira a proporcionar aos alunos o acesso aos conhecimentos sobre a relação saúde-doença fundamentais para as suas vidas.
Psychological, pedagogical and methodological principles of teaching dialogic foreign language speaking and the problem of classification of exercises
Authors: Kozachenko Oleksiy
Published: April 2021

The article provides a theoretical analysis of psychological, pedagogical and methodological principles of teaching dialogic speaking. The relevance of the study is related to the need for scientific development and implementation of a model related to teaching dialogic speaking, which will effectively develop quality skills and relevant competencies. The methodological basis for teaching dialogic speaking is the systemic dynamic unity of interconnected and interdependent situational semantic and linguistic characteristics of this form of speaking realised in the model. The article pays attention to the main provisions of the theory of verbal communication which are a real basis for building a system of situational teaching / learning of dialogic speaking within a single complex “situation – meaning – language”. The gradual approximating of educational situations to natural dialogue is based on a number of well-known didactic principles, the observance of which is considered by the author as an important component of the teaching / learning system. Theoretical analysis of the problem regarding classification of exercises for teaching dialogic speaking as the main element of the educational process has been carried out. Basing on the analysis, it has been determined that an exercise should comprise situational, semantic (meaning-centred) and linguistic characteristics of dialogic speech; whereas their systematic application, while being trained, should be aimed at mastering stylistically marked units alongside syntactic and lexical-syntactic phenomena typical for conversational style of dialogic speaking, as well as at practicing a set of operations of semantic order and operations related to the memory peculiarities. Taking into account all these aspects will allow building an effective model of teaching / learning, namely to clearly formulate the requirements to the main component of the education system, to select the most effective ones, as well as to integrate them into an overall model aimed at developing skills and abilities of dialogic foreign language speaking.
Training of pedagogical and research-pedagogical staff: international aspects
Authors: Yakovenko Olena
Published: April 2021

The article revises the issue of studying foreign experience in improving the professional development of teaching staff. Remarks are made on the need to modernise the system of advanced training of pedagogical and research-pedagogical staff. Updating the system of advanced training, the creation of new structures is one of the priority directions of state policy in any country; it is aimed at ensuring the professional growth of a specialist. The achievement of a new quality of education is associated with the reorientation of education for preparing people for life, for solving the issues related to guaranteed employment, for the requirements of a fleeting society and technological changes. Education is viewed as a lifelong process that needs not only to be corrected, but also changed and transformed. The main features of advanced training have been analysed; the peculiarities of advanced training intended for research-pedagogical staff in such foreign countries as the USA, Great Britain and Germany have been investigated. The author emphasises that postgraduate pedagogical education in these countries is distinguished by a structural diversity, a variety of content, forms and methods of education, which is grounded by the specific features of the countries’ historical development, national traditions and priorities of educational needs of research-pedagogical staff (RPS). At the same time, external factors significantly influence the systems that have formed in modern Ukraine: the processes of globalisation of society, the internationalisation of education, the activities of international organisations that accumulate progressive pedagogical ideas and put forward urgent requirements for its improvement. As the author notes, in Ukraine, the work to improve the system of advanced training of domestic RPS, as well as in other countries, is carried out in all directions, using modern forms and methods. However, the author singles out two problems: 1) unsatisfactory technical support; 2) some resistance to innovation due to the human factor. The author sees the further development of the subject in expanding the range of studied countries, studying the content of advanced training courses and in analysing advanced training programs intended for research-pedagogical staff.
Analysis of the English Textbook «Enterprise 4»
Authors: Nesin Yuri
Published: April 2021

Relevance of the study is substantiated by the need for the optimisation of foreign languages education in non-linguistic higher education establishments at economic faculties that are particularly influential on the process related to the acquisition and memorising of linguistic material. The purpose of the study is to analyse the English textbook «Enterprise 4» issued by the Publishing house «Express Publishing» as an effective means of communication. Special attention is paid to the correspondence of the content of the textbook to its aim, expediency of using the mentioned textbook at practical sessions at higher educational institutions at economic faculties by the students majoring in Hotel and Restaurant Business. The methods used are as follows: the methodological aspect of the textbook is stressed; the author emphasises a positive role of the data obtained and the introduction, underlining the aim of lessons for seekers of higher education. The scholar examines the usage of the most spread types of tests: asking-answering questions, translating, matching, completing, gap-filling, information transferring, recording, correcting, paragraphing, multiple choice, finding differences (similarities) and so on. Results: the article underlines the importance of the textbook’s functions, the necessity to include into the educational process such creative tasks as working out portfolios, group work, making notes, making up dialogues, organisation of discussions, presentations, role-playing. Unquestionable advantages of the “Enterprise 4” textbook are as follows: complete compatibility to the requirements of the teaching programs, prominent clarity of the material structuring, availability of technical support for the textbook users, visible scientific correctness in the contents and completeness in the revealing of the main issues, the use of up-to-date and generally accepted scientific terms. The lexical and grammar material is practice-oriented, its interactions with life is obvious. The textbook shows the ways to the differential approach to teaching new material; its content correlates with age characteristics of higher school students. The language of the mentioned material is clear and simple. One can trace comparative studies in the textbook (American English – British English reference book). Motivation of the youth’s learning activities, development of their interest to the subject by using the methods proposed in the textbook show the presence of problematic and searching tasks. The didactic adequacy of the tasks system given in the textbook, its capacity to facilitate students’ independent activities alongside the logic of the illustrative material layout and use are considerable advantages of the textbook as both a stand-alone and an additional information source. Conclusions: this article accents on further development of the four language activities at the English lessons – listening, speaking, reading and writing, as well as on four competences –linguistic, speaking, social-cultural and strategic (general learning) ones.