Analysis of Volatile Organic Compounds in the Apollo Next Generation Sample Analysis (ANGSA) 73002 Core Sample

Understanding the organic content of lunar regolith was an early priority upon the return of Apollo samples, with amino acids being of special interest because of their importance to life on Earth and their astrobiological relevance. Many initial studies focused on the detection of amino acids in these samples and attempts to determine the origin of those compounds. Although no consensus on the origin of the amino acids was reached in those early studies, more recent work determined that the detected amino acids originated from both terrestrial contamination and meteoritic or cometary in fall to the lunar surface. A majority of the amino acids in the Apollo samples studied originated from precursor molecules, either indigenous to the lunar samples or contaminants, that reacted during the water extraction and acid hydrolysis process for analysis in the laboratory, but the identities of the amino acid precursors still remain poorly understood. Such precursors could include hydrogen cyanide (HCN) and other volatile organic compounds such as amines, carboxylic acids, or aldehydes and ketones. The identities of these compounds, as well as the effects of years of curation on their abundances in lunar regolith samples stored at ambient temperature under nitrogen gas purge, are not clear. The specially curated samples available through the Apollo Next Generation Sample Analysis (ANGSA) program provide a unique opportunity to use state-of- the-art analytical techniques to examine previously unstudied lunar materials. The ANGSA samples include three types of samples: 1) samples stored frozen since <1 month after Earth arrival; 2) samples stored under helium; and 3) a double drive tube collected by Apollo 17 astronauts, with the bottom portion of the drive tube sealed under vacuum on the Moon and never opened. In contrast to the typically curated Apollo samples that have been kept for decades at room temperature under flowing nitrogen purge that may have significantly reduced the abundance of volatiles, the vacuum-sealed and frozen samples may have enhanced preservation of these volatiles. Our initial investigation examines amino acids and their potential volatile precursors, including hydrogen cyanide (HCN), aldehydes, ketones, amines, and mono-carboxylic acids, in a sample from the top portion of the Apollo 17 double drive tube. These results will aid in understanding the lunar abundances of these molecules and will also be compared to future analyses of other drive tube and frozen ANGSA samples

Health systems and global progress towards malaria elimination, 2000-2016

As more countries progress towards malaria elimination, a better understanding of the most critical health system features for enabling and supporting malaria control and elimination is needed.; All available health systems data relevant for malaria control were collated from 23 online data repositories. Principal component analysis was used to create domain specific health system performance measures. Multiple regression model selection approaches were used to identify key health systems predictors of progress in malaria control in the 2000-2016 period among 105 countries. Additional analysis was performed within malaria burden groups.; There was large heterogeneity in progress in malaria control in the 2000-2016 period. In univariate analysis, several health systems factors displayed a strong positive correlation with reductions in malaria burden between 2000 and 2016. In multivariable models, delivery of routine services and hospital capacity were strongly predictive of reductions in malaria cases, especially in high burden countries. In low-burden countries approaching elimination, primary health center density appeared negatively associated with progress while hospital capacity was positively correlated with eliminating malaria.; The findings presented in this manuscript suggest that strengthening health systems can be an effective strategy for reducing malaria cases, especially in countries with high malaria burden. Potential returns appear particularly high in the area of service delivery

Inter-observer variation in the assessment of clinical signs in sick Tanzanian children

We assessed the inter-observer agreement in identification of a range of 24 clinical signs associated with disease presentation in 327 children aged 0·41) although there was only fair agreement (Kappa-score 0·21-0·40) in the detection of neck stiffness and chest indrawing and slight agreement in the detection of dehydration (Kappa-score 0·199). All objective neurological signs were less reliably assessed in infants than in older children. The difficulties surrounding the diagnosis of impaired consciousness in young children should increase vigilance in the diagnosis and management of neurological complications of illnesses in infanc

Carbon isotope evidence for the substrates and mechanisms of prebiotic synthesis in the early solar system

Meteorites contain prebiotic, bio-relevant organic compounds including amino acids. Their syntheses could result from diverse sources and mechanisms and provide a window on the conditions and materials present in the early solar system. Here we constrain alanine’s synthetic history in the Murchison meteorite using site-specific ¹³C/¹²C measurements, reported relative to the VPDB standard. The δ¹³C_(VPDB) values of −29 ± 10‰, 142 ± 20‰, and −36 ± 20‰ for the carboxyl, amine-bound, and methyl carbons, respectively, are consistent with Strecker synthesis of interstellar-medium-derived aldehydes, ammonia, and low-δ¹³C nebular or interstellar-medium-derived CN. We report experimentally measured isotope effects associated with Strecker synthesis, and use them to constrain the δ¹³C values of the alanine precursors, which we then use to construct a model that predicts the molecular-average δ¹³C values of 19 other organic compounds of prebiotic significance found in Murchison if they were made by our proposed synthetic network. Most of these predictions agree with previous measurements, suggesting that interstellar-medium-derived aldehydes and nebular and/or pre-solar CN could have served as substrates for synthesis of a wide range of prebiotic compounds in the early solar system

Carbon isotope evidence for the substrates and mechanisms of prebiotic synthesis in the early solar system

Meteorites contain prebiotic, bio-relevant organic compounds including amino acids. Their syntheses could result from diverse sources and mechanisms and provide a window on the conditions and materials present in the early solar system. Here we constrain alanine’s synthetic history in the Murchison meteorite using site-specific ¹³C/¹²C measurements, reported relative to the VPDB standard. The δ¹³C_(VPDB) values of −29 ± 10‰, 142 ± 20‰, and −36 ± 20‰ for the carboxyl, amine-bound, and methyl carbons, respectively, are consistent with Strecker synthesis of interstellar-medium-derived aldehydes, ammonia, and low-δ¹³C nebular or interstellar-medium-derived CN. We report experimentally measured isotope effects associated with Strecker synthesis, and use them to constrain the δ¹³C values of the alanine precursors, which we then use to construct a model that predicts the molecular-average δ¹³C values of 19 other organic compounds of prebiotic significance found in Murchison if they were made by our proposed synthetic network. Most of these predictions agree with previous measurements, suggesting that interstellar-medium-derived aldehydes and nebular and/or pre-solar CN could have served as substrates for synthesis of a wide range of prebiotic compounds in the early solar system

Evaluating the performance of spectral indexes for identify high Andean wetlands

[EN] High Andean wetlands are habitats critical to life forms that have adapted to these extreme high mountain ecosystems, and for living beings that inhabit the lower parts of the basin; they are spaces that contain high diversity of flora and fauna characteristic of these places and are strongly associated with the water component. There lies the importance of identifying and monitoring ecosystems, using easy applicable methods and allowing results every two weeks approximately, they are inexpensive and highly reliable. Methods of monitoring in short periods, they are economically profitable and provide reliable information, they correspond to the evaluations by satellite images, specifically applying the methods of spectral indices. Thereby, the objective of the research was to evaluate the performance of six indices, considered to be the most used to identify high Andean wetlands (humidity index at surface level, normalized difference water index, normalized difference vegetation index, enhanced vegetation index, index of vegetation to the surface and tasseled CAP vegetation), in periods of low precipitation, using imagery Landsat 8 OLI. Comparing the performance of those indexes in the identification of wetlands through cross-validation and bootstrap statistical learning, the index that showed better performance was tasseled CAP vegetation, revealing the lowest value of the average of the mean square error of iterations between the test failure rate and training. The index tasseled CAP vegetation, shows greater reliability to identify and evaluate high Andean wetlands.[ES] Los humedales altoandinos son hábitats fundamentales para las formas de vida que se han adaptado a estos ecosistemas extremos de alta montaña, y para los seres vivos que habitan en las partes bajas de la cuenca; son espacios que albergan alta diversidad de flora y fauna propias de estos lugares y están fuertemente asociados con el componente hídrico. De allí radica la importancia de identificar y monitorear, utilizando métodos fácilmente aplicables y que permitan obtener resultados cada dos semanas aproximadamente, que sean poco costosos y altamente confiables. Los métodos de monitoreo en periodos cortos, económicamente rentables y proveen información confiable, corresponden a las evaluaciones mediante imágenes satelitales, específicamente aplicando los métodos de índices espectrales. De tal modo, el objetivo de la investigación fue evaluar el desempeño de seis índices, considerados como los más utilizados para identificar humedales altoandinos (índice de humedad a nivel de superficie, índice de diferencia normalizada de agua, índice de vegetación de diferencia normalizada, índice de vegetación mejorada, índice de vegetación ajustada a la superficie y tasseled CAP vegetación), en periodos de escasa precipitación, utilizando imágenes Landsat 8 OLI. Comparando el desempeño de los referidos índices en la identificación de humedales mediante el aprendizaje estadístico de validación cruzada y bootstrap, el índice que mostró mejor desempeño fue tasseled CAP vegetación, revelando el valor más bajo del promedio de error medio cuadrático de las iteraciones entre la tasa de error de prueba y el entrenamiento. El índice tasseled CAP vegetación, muestra mayor confiabilidad para identificar y evaluar humedales altoandinos.Aponte-Saravia, J.; Ospina-Noreña, JE. (2019). Evaluando el desempeño de índices espectrales para identificar humedales alto andinos. Revista de Teledetección. (53):59-72. https://doi.org/10.4995/raet.2019.10580SWORD59725

El profesor universitario: integración entre lo personal y lo profesional

En la primera parte de este artículo se explica cómo afectan a la labor docente ciertos cambios sociales y culturales, como son el surgimiento de la sociedad del conocimiento, la orientación hacia el mercado por parte de las universidades, las exigencias y presiones a los profesores para publicar, la pérdida del sentido ético en la actividad académica y la disparidad de tareas que hoy se le asignan al profesor universitario. A raíz de lo anterior, se propone un modelo comprensivo de docente universitario compuesto por dos ejes o vertientes ¿lo personal y lo profesional¿, que incorpora y sintetiza diferentes aportaciones sobre este tema. Finalmente, se defiende la necesidad de entender la labor docente universitaria como una vocación, en el sentido más hondo de la palabra; una vocación lleva consigo la inclinación a perseguir un fin: la formación y educación de los estudiantes que tenemos encomendados

Feasibility Study on Offshore Polymer Flooding, Forecasting Production Through Integrated Asset Modelling, A Technical and Economic Approach

Substantial percentage of current world oil production derives from mature fields and the rate of replacement of the produced reserves by new discoveries has been declining in the previous years. In order to sustain such upsurge in the demand for economical energy throughout the world, the recoverable oil resources in known reservoirs can be produced economically by applying EOR techniques. The following work is a comprehensive review of offshore polymer flooding through Integrated Asset Modelling (IAM). Polymer flooding has been one of the emerging EOR techniques in offshore environment in the recent decades. The pilot implementation of polymer flooding has proved to be challenging due to the difficulties associated with the operational facilities and the high Capital Expenditure (CAPEX) required to initiate the project. Coupling the IAM technique to such project would provide valuable insight to the current and future field production levels and expected operating conditions. IAM can add essential values in areas of field and well optimization, production forecasting, operational decision making and effect of extending field life on surface and subsurface facilities