Paleomagnetism and aeromagnetic survey from Tancitaro volcano (Central Mexico) - paleo-secular variation at low latitudes during the past 1 Ma

"El volcán Tancítaro (TV) forma parte del campo volcánico monogenético MichoacánGuanajuato (MGVF) en el sector centro-oeste del Eje Volcánico Trans Mexicano (TMVB). Los resultados de un estudio paleo magnético de flujos de lava del volcán Tancítaro fechados radiométricamente, se utilizaron para investigar la variación paleo secular (PSV) y el campo promedio temporal (TAF) para latitudes bajas. El rango de fechado Ar-Ar fue de 70 a 960 kaños considerando los Chrones de polarización de Brunhers y Matuyama. Todas las muestras arrojaron una polaridad de magnetización normal bien definida. Dos flujos se correlacionaron con la polaridad del Evento Jaramillo, lo cual provee un marcador útil para la actividad volcánica en el MGVF. Para los análisis del PSV y TAF las paleo direcciones se combinaron con resultados anteriores de alta precisión. El estudio aeromagnético alrededor del volcán Tancítaro se caracterizó por una serie de anomalías tanto positivas como negativas. El Volcán Tancítaro presenta una gran anomalía positiva que sugiere la presencia de una gran fuente subterránea. El análisis espectral de este campo anómalo da una estimación promedio hacia la parte alta de los cuerpos que la originan entre 2-3 km.""The Tancitaro volcano (TV) is part of the Michoacan-Guanajuato monogenetic volcanic field (MGVF) in the central-western sector of the Trans-Mexican Volcanic Belt (TMVB). Results of a paleomagnetic study of radiometrically dated lava flows from Tancitaro volcano were used to investigate the paleosecular variation (PSV) and time averaged field (TAF) at low latitudes. Ar-Ar dates range from ~70 to 960 kyr spanning the Brunhes and Matuyama polarity chrons. All samples yielded well defined normal polarity magnetization. Two flows are correlated to the Jaramillo polarity event, which provide a useful marker for the volcanic activity in the MGVF. For the PSV and TAF analysis, paleodirections were combined with previously reported high standard results. The aeromagnetic survey around the Tancitaro volcano was characterized by a trend of regional anomalies over the volcanic structures. The residual field showed several positive and negative anomalies. The Tancitaro volcano is marked by a broad positive anomaly suggesting the presence of a large underground source. Spectral analysis of this anomaly field gives an average estimate to the top of the source bodies between 2-3km.

Thermoluminiscence vs. archaeomagnetism: Absolute dating of prehispanic pottery fragments from the northwestern andes (Piedras Blancas, Medellin, Colombia)

Las dataciones absolutas realizadas tanto mediante arqueomagnetismo como por termoluminiscencia ofrecen aportaciones cronológicas importantes debido a que la datación se hace directamente sobre el objeto quemado. Esto no sucede así con la datación por radiocarbono, que es el método más utilizado en arqueología. En este trabajo hemos determinado la arqueointensidad absoluta geomagnética registrada en fragmentos cerámicos provenientes de los Andes noroccidentales (Colombia), los cuales habían sido previamente datados mediante el método de termoluminiscencia. Las muestras estudiadas consisten en un fragmento cerámico de olla asociado a un contexto doméstico y otro fragmento de volante de uso troncocónico, con decoración incisa fina rellena de pasta blanca, hallados en el sitio arqueológico Piedras Blancas (Medellín, Colombia). Los intervalos de edades obtenidos mediante el método arqueomagnético son relativamente amplios debido a la escasa precisión de la curva de referencia de variación secular para el intervalo de edad considerado. En cambio, la termoluminiscencia aporta edades absolutas mejor definidas y de mayor precisión.Absolute dating by means of archaeomagnetism and thermoluminescence offer important chronological contributions because burned objects are dated directly. This is not true for the most common absolute dating method used in archaeology today, radiocarbon dating. In this survey we have determined the absolute geomagnetic archaeointensity recorded in ceramic fragments from the northwestern Andes (Colombia) which had previously been dated using thermoluminescence. The samples studied consist of a ceramic pot fragment associated with a domestic context and a truncated-cone shaped spindle whorl fragment with thin incised decoration and filled with white paste found at the Piedras Blancas archaeological site (Medellin, Colombia). The age ranges obtained by the archaeomagnetic method are relatively high due to the insufficient precision of the secular variation reference curve for the age interval considered, while thermoluminescence provides better defined and more accurate absolute ages.Fil: Obregón, Mauricio. Universidad Nacional Autónoma de México; MéxicoFil: Ramírez Luna, Ángel. Universidad Nacional Autónoma de México; MéxicoFil: Goguitchaichvili, Avto. Universidad Nacional Autónoma de México; MéxicoFil: Cejudo, Ruben. Universidad Nacional Autónoma de México; MéxicoFil: Morales, Juan. Universidad Nacional Autónoma de México; MéxicoFil: Cervantes Solano, Miguel. Universidad Nacional Autónoma de México; MéxicoFil: Greco Mainero, Mariano Catriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Geología; Argentin

Compota de zapallo (Cucúrbita máxima Dutch.) para infantes, funcional, de bajo costo, sin conservantes y de considerable tiempo de vida útil: características reológicas, sensoriales, fisicoquímicas, nutritivas y microbiológicas

The research aimed to develop a children's pumpkin compote, functional, inexpensive, preservative-free and of considerable shelf life. The effect of incorporating xanthan gum (XG) was evaluated at three concentrations (0.10%, 0.15% and 0.20%) on its rheological properties. Sensory characteristics were applied to 60 panelists (30 undergraduate students and 30 children between 2 and 3 years). Its physical, physicochemical, and microbiological characteristics were determined. With the pH values was estimated the shelf life of pumpkin compote using accelerated testing method. The product was stored at 20 °C, 30 °C and 40 °C for 0, 10, 20, and 30 days. The results show the pumpkin compote presented non-Newtonian behavior, pseudoplastic, and was adjusted to the Ostwald Waele model (R2 > 0.98). Compote formulated with 0.15% of XG was conceived as the best treatment, with a "Like" scale for color attributes, smell, texture, taste and general appearance (3.80 to 4.13 points) associated with the presence of 82.45% humidity, 5.40 pH, 17 °Brix, and absence of molds, yeasts and total coliforms. Influence of temperature on viscosity was modeled using Arrhenius equation, showing a decrease in viscosity with increasing temperature. Finally, the estimated shelf life at 20 °C, 30 °C and 40 °C were 125, 75, and 45 days, respectively.La investigación tuvo por objetivo elaborar una compota de zapallo para infantes, funcional, de bajo costo, sin conservantes y de considerable tiempo de vida útil. Fue evaluado el efecto de la incorporación de goma xantana (GX) a tres concentraciones (0,10%, 0,15% y 0,20%) sobre sus propiedades reológicas. Las características sensoriales fueron aplicadas a 60 panelistas (30 estudiantes nivel pregrado y 30 niños entre 2 a 3 años). Se determinaron sus características físicas, fisicoquímicas y microbiológicas. Con los valores de pH, se estimó la vida útil de la compota de zapallo a través del método de pruebas aceleradas a 20 °C, 30 °C y 40 °C y durante 0, 10, 20, y 30 días. Los resultados mostraron que la compota presentó un comportamiento no-newtoniano, pseudoplástico y ajustado al modelo de Ostwald de Waele (R2 > 0,98). La compota formulada con 0,15% de GX se concibe como el mejor tratamiento, con nivel de “Me gusta” para los atributos de color, olor, textura, sabor y apariencia general (3,80 a 4,13 puntos), asociado a la presencia de 82,45% de humedad, 5,40 de pH, 17 °Brix, y ausencia de mohos, levaduras y coliformes totales. La influencia de la temperatura en la viscosidad se modeló utilizando la ecuación de Arrhenius, mostrando una disminución en la viscosidad con el aumento de la temperatura. Finalmente, la vida útil estimada a 20 °C, 30 °C y 40 °C fue de 125, 75 y 45 días, respectivamente

Diminishing benefits of urban living for children and adolescents’ growth and development

Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified

Diminishing benefits of urban living for children and adolescents’ growth and development

AbstractOptimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was &lt;1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified.</jats:p

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI 2 SD above the median). Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining https://researchonline.ljmu.ac.uk/images/research_banner_face_lab_290.jpgunderweight or thinness. Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesity

Paleosecular variation and absolute geomagnetic paleointensity records retrieved from the Early Cretaceous Posadas Formation (Misiones, Argentina)

The Early Cretaceous may be considered a key period for understanding the evolution of the Earth's magnetic field. Some still unsolved problems are related to the mode of paleosecular variation (PSV) of the Earth's magnetic field before and during the Cretaceous Normal Superchron. We report here a detailed rock-magnetic, paleomagnetic and paleointensity investigation from 28 lava flows (331 standard paleomagnetic cores) collected in the Argentinean part of the Parana Flood Basalts (Formation Posadas) in order to contribute to the study of PSV during the early Cretaceous and to obtain precise Cretaceous paleomagnetic pole positions for stable South America. The average paleofield direction is precisely determined from 26 sites, which show small within-site dispersion and high directional stability. Five sites show evidences for the self-reversal of thermoremanent magnetization. 23 sites yielded normal polarity magnetization and only 3 are reversely magnetized. Moving windows averages were used to analyze the sequential variation of virtual geomagnetic pole's (VGP) axial positions. Interestingly, the axial average VGP path traces an almost complete cycle around the geographical pole and passes near the location of all previously published Paraná Magmatic Province poles. Both paleomagnetic poles and average VGP paths are significantly different from the pole position suggested by fixed hotspot reconstructions, which may be due to true polar wander or the hotspot motion itself. Only 15 samples from 5 individual basaltic lava flows, yielded acceptable paleointensity estimates. The site mean paleointensities range from 25.2 ± 2.2 to 44.0 ± 2.2 μT. The virtual dipole moments (VDMs) range from 4.8 to 9.9 × 1022 Am2. This correspond to a mean value of 7.7 ± 2.1 × 1022 Am2 which is 96% of the present day geomagnetic field strength. These intensities agree with the relatively high values already reported for Early Cretaceous, which are consistent with some inferences from computer simulations previously published.Fil: Mena, Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Goguitchaichvili, Avto. Universidad Nacional Autónoma de México; MéxicoFil: Solano, Miguel Cervantes. Universidad Nacional Autónoma de México; MéxicoFil: Vilas, Juan Francisco A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentin

DATACIÓN DE TINAJAS ARQUEOLÓGICAS DEL SITIO GUACHIMONTONES, OCCIDENTE DE MESOAMÉRICA (Dating of Archaeological Jars from the Guachimontones Site, Western Mesoamerica)

El presente trabajo analiza un conjunto de fragmentos cerámicos correspondientes a tinajas de gran tamaño recuperadas en el sector de Talleres del sitio arqueológico Guachimontones, Jalisco, México (fig. 1). La cerámica en estudio guardaba relación con unidades habitacionales, sin embargo se desconocía su funcionalidad en este espacio. Por tal motivo se aplicaron técnicas arqueométricas y arqueomagnéticas para conocer su uso específico, su funcionamiento dentro de la organización social y su cronología. El punto de partida del análisis es la idea de que estas tinajas sirvieron para la preparación de tejuino (bebida fermentada elaborada a partir de maíz); esto se debe, en gran medida, a las comparaciones etnográficas con otras regiones. Los resultados obtenidos de la datación arqueomagnética nos permitieron comprobar que las tejuineras son parte del periodo Posclásico del sitio, y que las edades obtenidas son muy similares a las ya publicadas para el Posclásico del sitio arqueológico de Guachimontones. ENGLISH: This paper analyzes a set of ceramic fragments from giant jars (tejuineras) recovered within the Guachimontones archaeological site, Jalisco State, Mexico. These jars, found at several ceramic workshops, are related to housing units. However, until now the use of these objects and their temporality has been unclear. In order to better characterize and date the archaeological context, archaeometric and archaeomagnetic investigations were performed. The starting point for the analysis is the idea that the jars were used for the preparation of tejuino (fermented drink made from corn); in large part, this theory is based on ethnographic comparisons with other regions. Through archaeomagnetic dating, it was found that tejuineras are dated to the Postclassic period, and that the dates obtained were very similar to those already published for the Guachimontones archaeological site

INTERVENCIÓN ARQUEOMAGNÉTICA DEL HORNO DE LA HACIENDA SAN PEDRO CHOLUL (MÉRIDA, YUCATÁN) (Archaeomagnetic Dating of a Kiln from the San Pedro Cholul Hacienda (Merida, Yucatan))

En el presente trabajo se reportan los resultados de un estudio arqueomagnético realizado en un horno para la quema de cal encontrado en la hacienda henequenera de San Pedro Cholul, localizada al noroeste de la ciudad de Mérida en el estado de Yucatán, México. La finalidad del estudio es establecer una cronología confiable y analizar las posibles consecuencias sociales, económicas y ambientales de este asentamiento, el cual existió posiblemente desde mediados del siglo XIX hasta los años sesenta del siglo pasado. Para la determinación de la cronología, se utilizó el método de datación arqueomagnética a estructuras pirotecnológicas de estas características. Las muestras estudiadas provienen de rocas y ladrillos del horno y arrojan una edad entre 1835 y 1896, la cual concuerda con la información histórica disponible y se interpreta como el periodo de producción más importante de la región. ENGLISH: This paper presents the results of an archaeomagnetic study carried out on a lime burning kiln at the henequen hacienda of San Pedro Cholul (northwest of the city of Merida in the state of Yucatan, Mexico). The purpose of the study is to establish a reliable chronology and to estimate the possible social, economic and environmental implications of this settlement, which may have existed from the middle of the nineteenth century until the 1960s. Archaeomagnetic dating was carried out on samples obtained from rocks and bricks from the kiln and give an age between 1835 and 1896. This date range agrees with available historical information and is interpreted as the most important production period of the region

MÁS DE 100 AÑOS ININTERRUMPIDOS DE REGISTRO GEOMAGNÉTICO EN MÉXICO: IMPLICACIONES EN LA DATACIÓN ABSOLUTA DE ALGUNOS EDIFICIOS HISTÓRICOS (More than 100 Uninterrupted Years of Geomagnetic Record in Mexico: Implications in the Absolute Dating of Some Historic Buildings)

En México funciona con regularidad, desde el año 1914, el Observatorio Geomagnético de Teoloyucan, proporcionando un registro casi continuo de la variación secular del campo magnético terrestre. En el presente trabajo se presenta una síntesis del registro geomagnético obtenido en México desde hace más de cien años. Con estos datos se ofrece una curva de variación secular regional la cual, dada su calidad técnica, se propone como herramienta de datación arqueomagnética para este intervalo de tiempo. ENGLISH: In Mexico, the Teoloyucan Geomagnetic Observatory has been operating regularly since 1914, providing an almost continuous record of the secular variation of the Earth's magnetic field. This work offers a synthesis of the geomagnetic record obtained in Mexico for more than one hundred years. With these data, we propose a regional secular variation curve which, given its technical quality, is proposed as an archaeomagnetic dating tool for this time interval