Inference of fault and fracture systems beneath the Matatlan waste dump basement, a VLF study

AbstractWe used the VLF technique to infer fault or major fracture zones that might serve as path for contaminant waste fluids in the Matatlan dumpsite, in Guadalajara, western Mexico. To interpret the data we used the Fraser, and Karous-Hjelt filters.Profiles were interpreted with 2D direct modeling based on Karous-Hjelt modified filter (K-H). The Fraser and Karous-Hjelt conjugated filter were applied to the entire data. The results of both techniques show similarities in the directions and positions of anomalous features, which are assumed fault or fracture zones. We observed one fault zone at the centre of the site, with a NEE-SWW strike. Other important inferred structures have NW-SE directions at the western part of the site.The cooperative use of both techniques, based on K-H filter and the Fraser filter give results as an N-S inferred structure in the westernmost part of the zone, as well as NW-SE linear anomalies, mainly in the western half of the site. The N-S structure has the same direction as that of Rio Grande de Santiago Canyon. The NW-SE features coincide with the directions of the Tepic-Zacoalco rift. Others NE-SW lineaments are located towards the centre of the area. These facts coincide strongly with the predominance of fracture groups show in the fracture analysis. The inferred structures could serve as conduits for the leachates to migrate towards the Coyula canyon as well as towards the Rio Grande de Santiago Canyon.Statistic analysis of fracture orientations showed N-S (A), N75-80E (B), N60-65W (C), and N25-30W (D) main directions, and N45-55E (E), and 90E (F) secondary directions. Group A coincides with the direction of the Rio Grande de Santiago Canyon, whereas pattern F have the same direction as Coyula Canyon

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Clustering COVID-19 ARDS patients through the first days of ICU admission. An analysis of the CIBERESUCICOVID Cohort

Background Acute respiratory distress syndrome (ARDS) can be classified into sub-phenotypes according to different inflammatory/clinical status. Prognostic enrichment was achieved by grouping patients into hypoinflammatory or hyperinflammatory sub-phenotypes, even though the time of analysis may change the classification according to treatment response or disease evolution. We aimed to evaluate when patients can be clustered in more than 1 group, and how they may change the clustering of patients using data of baseline or day 3, and the prognosis of patients according to their evolution by changing or not the cluster.Methods Multicenter, observational prospective, and retrospective study of patients admitted due to ARDS related to COVID-19 infection in Spain. Patients were grouped according to a clustering mixed-type data algorithm (k-prototypes) using continuous and categorical readily available variables at baseline and day 3.Results Of 6205 patients, 3743 (60%) were included in the study. According to silhouette analysis, patients were grouped in two clusters. At baseline, 1402 (37%) patients were included in cluster 1 and 2341(63%) in cluster 2. On day 3, 1557(42%) patients were included in cluster 1 and 2086 (57%) in cluster 2. The patients included in cluster 2 were older and more frequently hypertensive and had a higher prevalence of shock, organ dysfunction, inflammatory biomarkers, and worst respiratory indexes at both time points. The 90-day mortality was higher in cluster 2 at both clustering processes (43.8% [n = 1025] versus 27.3% [n = 383] at baseline, and 49% [n = 1023] versus 20.6% [n = 321] on day 3). Four hundred and fifty-eight (33%) patients clustered in the first group were clustered in the second group on day 3. In contrast, 638 (27%) patients clustered in the second group were clustered in the first group on day 3.Conclusions During the first days, patients can be clustered into two groups and the process of clustering patients may change as they continue to evolve. This means that despite a vast majority of patients remaining in the same cluster, a minority reaching 33% of patients analyzed may be re-categorized into different clusters based on their progress. Such changes can significantly impact their prognosis

Multi-scale analysis of well-logging data in petrophysical and stratigraphic correlation

Determinación de los límites locales de una columna estratigráfica (por ejemplo relacionados con ambientes de depósito) representan en particular una gran contribución al análisis y caracterización de yacimientos petroleros. En este marco general, las Transformadas de Ondícula, continua y discreta, son aplicadas a datos de registros geofísicos de pozos de un área productora de aceite en el Golfo de México, con el propósito de encontrar periodicidades o ciclos y correlacionarlos con las características litológicas y estratigráficas de los ambientes asociados. Un análisis multiescala de registros geofísicos de pozos (rayos gama, resistividad y potencial espontáneo) fue realizado basado en la transformada de ondicular. En particular los coeficientes ondiculares fueron determinados. El análisis de los escalogramas-espectrogramas permitió obtener pseudolongitudes de onda características para cada escala (frecuencias). Las pseudolongitudes de onda fueron asociadas con posibles periodicidades o periodos deposicionales (ciclos climáticos de Milankovitch) del área de estudio. El caso presentado muestra que el análisis ondicular es una técnica complementaria de gran ayuda para la caracterización de yacimientos, particularmente en la localización de secuencias estratigráficas y de las facies asociadas. doi: https://doi.org/10.22201/igeof.00167169p.2010.49.2.11

Eliminated aliasing effect on wavelet transform based multiresolution analysis

El análisis multiresolución basado en la transformada ondicular discreta se incorpora al procesamiento de señales sísmicas. Ésta técnica de análisis permite descomponer una señal sísmica en diferentes bandas de frecuencia, y así analizar la información contenida en dichas bandas. El análisis de multiresolución permite visualizar en el dominio del tiempo la información contenida en las bandas de frecuencia. Las ondículas usadas comúnmente en la transformada ondicular discreta presentan un traslape entre escalas, lo que da origen a un efecto aliasing e introduce información espuria. La ondícula Vaidyanathan minimiza el traslape entre escalas. Aplicamos esta ondícula a datos sintéticos y a un cubo sísmico 3D. De acuerdo a este estudio, los efectos espurios generados por el traslape entre escalas es minimizado con la ondícula Vaidyanathan. doi: https://doi.org/10.22201/igeof.00167169p.2016.55.3.172

Chapala half-graben structure inferred. A magnetometric study

El Lago de Chapala se ubica en una gran depresión topográfica rodeada de amplias me- setas volcánicas del Mioceno medio al tardío. Muchos estudios geológicos y tectónico-estructurales se refieren a la estructura interna de esta depresión topográfica como un graben o genéricamente como rift, aunque su estructura interna no ha sido formalmente establecida. Para este fin se realizó un levantamiento magnético constituido por cinco líneas norte-sur que cruzan al Lago de Chapala. Un perfil se extiende hacia el sur sobre caminos transitables. Las anomalías magnéticas son principalmente suaves y de carácter regional, lo que se debe al relleno sedimentario; anomalías de carácter local son debidas a bloques someros inclinados de composición basáltica y andesítica, y amplitudes altas debidas a flujos de lavas basálticas expuestas en las islas de Los Alacranes y Mezcala. Los modelados indican la presencia de un alto estructural que separa dos bajos estructurales. Los bajos estructurales constituyen estructuras tipo semigraben. A través de las fallas que delimitan este alto estructural se emplazaron los flujos basálticos de las Islas de Los Alacranes y Mezcala. La presencia de estructuras tipo semigraben implican que la corteza ha estado sometida a una tectónica de extensión. Una extensión profunda que adelgazó la corteza podría estar en el origen de las estructuras de tipo semigraben que caracterizan a la depresión Chapala. doi: https://doi.org/10.22201/igeof.00167169p.2015.54.4.169

The structure of the Goulfey-Tourba sedimentary basin (Chad-Cameroon): a gravity study

Se reporta un estudio gravimétrico de la cuenca Goulfey-Tourba, sureste del Lago Chad, norte del Camerún, cuyo objetivo ha sido establecer las principales características estructurales de la corteza somera. Se interpreta, en terminos de la información geológica disponible, las anomalias regional y residual. Análisis espectral y modelado 2.5D de tres perfiles seleccionados del mapa de anomalía residual proporcionan profundidades al basamento de 4.0, 2.0, y 2.9 km. Estas profundidades constriñen los modelos gravimétricos a lo largo de los perfiles, e indican que el relleno sedimentario tiene espesores variables. De esta forma, se tienen tres sub-cuencas a lo largo de la depresión de Goulfey-Turba (Goulfey, Tom-Merifine, y Tourba). Estas subcuencas son de origen tectónico. Ellas están asociadas con la tectónica de extension que ha afectado la region que va de la depresion de Benue hasta la cuenca de Chad. La sub-cuenca de Goulfey es la más profunda. El relleno sedimentario está probablemente constituido por arenas arcillosas de depositos aluviales, areniscas o margas. Las profundidades al basamento fueron constreñidas por los resultados del análisis espectral. El basamento comprende granite y gneiss, con intrusiones basálticas. Las fallas inferidas son de tipo normal. doi: https://doi.org/10.22201/igeof.00167169p.2010.49.4.12