Bioevents and redox conditions around the Cenomanian-Turonian anoxic event in Central Mexico

The Xilitla section of central Mexico (western margin of the proto-North Atlantic) is characterized by pelagic sediments enriched in marine organic matter. Using biostratigraphic and radiometric data, it was dated at the latest Cenomanian-earliest Turonian transition. We identified an interval coeval with the faunal turnover associated with the Oceanic Anoxic Event 2 (OAE 2), recording the Heterohelix shift and thePeer ReviewedPreprin

Redox conditions and authigenic mineralization related to cold seeps in central Guaymas Basin, Gulf of California

Authigenic carbonate crusts, surface muds and bivalve shell fragments have been recovered from inactive and active recently discovered cold seep sites in central Guaymas Basin. In this study, for first time, redox conditions and fluid sources involved in mineral precipitation were investigated by analyzing the mineralogy and textures of surface samples, along with skeletal contents, and C, O and S isotopes variations. The d13C values of aragonitic bivalve shells and non-skeletal carbonate from some surface muds (1‰ to -3.7‰ V-PDB) suggest that carbonate precipitated from ambient dissolved inorganic carbon, whereas fibrous aragonite cement and non-skeletal carbonate from other sites are highly depleted in 13C (down to -47.6‰ V-PDB), suggesting formation via anaerobic oxidation of methane, characteristic of methane seepage environments. d18O in most of the carbonates varies from +1.4‰ to +3.2‰ V-PDB, indicating that they formed from slightly modified seawater. Some non-skeletal carbonate grains from surface muds have lower d18O values (-12.5‰ to -8.2‰ V-PDB) reflecting the influence of 18O-depleted pore water. Size distribution of pyrite framboids (mean value: 3.1¿µm) scattered within diatomaceous sinter suggests formation from anoxic-sulfidic bottom waters. d34S in pyrite is of -0.3‰ V-CDT compared to +46.6‰ V-CDT in barite, thus implying a fluid sulfate-sulfide fractionation of 21.3‰ that argues in favor of microbial sulfate reduction as the processes that mediated pyrite framboid formation, in a semi-closed system. Barite formation occurred through the mixing of reducing and Ba-rich seep fluids with a 34S-enriched sulfate pool that resulted from microbial sulfate reduction in a semi-closed system. The chemical composition of aragonite cement, barite and pyrite suggest mineral precipitation from modified seawater. Taken together, our data suggest that mineralization at the studied seep sites is controlled by the mixing of seawater with minor amounts of hydrothermal fluids, and oxygen-depleted conditions favoring anaerobic microbial processes.Peer ReviewedPostprint (author's final draft

Characteristics and Evolution of sill-driven off-axis hydrothermalism in Guaymas Basin – the Ringvent site

The Guaymas Basin spreading center, at 2000 m depth in the Gulf of California, is overlain by a thick sedimentary cover. Across the basin, localized temperature anomalies, with active methane venting and seep fauna exist in response to magma emplacement into sediments. These sites evolve over thousands of years as magma freezes into doleritic sills and the system cools. Although several cool sites resembling cold seeps have been characterized, the hydrothermally active stage of an off-axis site was lacking good examples. Here, we present a multidisciplinary characterization of Ringvent, an ~1 km wide circular mound where hydrothermal activity persists ~28 km northwest of the spreading center. Ringvent provides a new type of intermediate-stage hydrothermal system where off-axis hydrothermal activity has attenuated since its formation, but remains evident in thermal anomalies, hydrothermal biota coexisting with seep fauna, and porewater biogeochemical signatures indicative of hydrothermal circulation. Due to their broad potential distribution, small size and limited life span, such sites are hard to find and characterize, but they provide critical missing links to understand the complex evolution of hydrothermal systems

Characteristics and Evolution of sill-driven off-axis hydrothermalism in Guaymas Basin – the Ringvent site

The Guaymas Basin spreading center, at 2000 m depth in the Gulf of California, is overlain by a thick sedimentary cover. Across the basin, localized temperature anomalies, with active methane venting and seep fauna exist in response to magma emplacement into sediments. These sites evolve over thousands of years as magma freezes into doleritic sills and the system cools. Although several cool sites resembling cold seeps have been characterized, the hydrothermally active stage of an off-axis site was lacking good examples. Here, we present a multidisciplinary characterization of Ringvent, an ~1 km wide circular mound where hydrothermal activity persists ~28 km northwest of the spreading center. Ringvent provides a new type of intermediate-stage hydrothermal system where off-axis hydrothermal activity has attenuated since its formation, but remains evident in thermal anomalies, hydrothermal biota coexisting with seep fauna, and porewater biogeochemical signatures indicative of hydrothermal circulation. Due to their broad potential distribution, small size and limited life span, such sites are hard to find and characterize, but they provide critical missing links to understand the complex evolution of hydrothermal systems

Agentes implicados en infección neonatal nosocomial y patrones de sensibilidad antimicrobiana

Con el objeto de conocer los agentes implicados en las infecciones nosocomiales y su susceptibilidad antimicrobiana en pacientes del Servicio de Neonatología, se realizó un estudio prospectivo en 101 aislamientos bacterianos, analizándose los casos de sepsis nosocomial. Se identificó la susceptibilidad de las cepas por métodos bacteriológicos convencionales, con medios de cultivo universales y selectivos. Se calculó la frecuencia de infecciones por 100 ingresos y se analizó la sensibilidad. La incidencia de sepsis neonatal nosocomial fue 36.4%. Predominaron bacterias gramnegativas ( Klebsiella pneumoniae, Escherichia coli y no fermentadores) (54.4%), seguido por bacterias grampositivas ( Staphylococcus aureus y Staphylococcus coagulasa negativo) (37.6%) y hongos (7.9%). La susceptibilidad a aminoglucósidos fue 28%. Para la Ciprofloxacina la sensibilidad para las Klebsiella fue 56.2%. Con respecto al cefepime y cefalosporinas de 3ra generación, la sensibilidad para los no fermentadores fue 50%. En cuanto al meropenem, Escherichia coli fue 54.4% sensible, Klebsiella 65.5%, y los no fermentadores 50%. Para piperacilina-tazobactam, Escherichia coli , Klebsiella y no fermentadores fueron sensibles en 45.4%, 40.6 % y 50%, respectivamente. La susceptibilidad al Colistin fue de 83.3% en los no fermentadores; Klebsiella 71.8% y Escherichia coli 63.6%. La sensibilidad del Staphylococcus aureus a la oxacilina fue de 18,7%, al linezolid, teicoplamina y vancomicina de 100%. El Staphylococcus coagulasa negativo fue 100% sensible a linezolid, teicoplanina y vancomicina y 46,6 % a clindamicina. Se pudo constatar la estabilidad en la circulación de los agentes causales, predominando las bacterias gramnegativas, y la baja susceptibilidad a la terapia antimicrobiana utilizada

Microfacies analysis and paleoenvironmental dynamic of the Barremian-Albian interval in Sierra del Rosario, eastern Durango state, Mexico

The detailed microfacies analysis on a stratigraphic section located in eastern Durango contribute to the paleoenvironmental and paleogeographic understanding of the Cupido and Coahuila carbonate platforms in the southern part of the Coahuila basement block, a poorly investigated area. The stratigraphic section herein studied spans the Barremian-Albian interval and is composed of the upper Cupido, La Peña and Upper Tamaulipas formations. The recognition of this latter unit in the eastern part of the Durango state is a significant contribution to the stratigraphic scheme of the southern part of the Sierra del Rosario. The studied interval of the Cupido Formation is represented by different microfacies associations: 1) peritidal and subtidal facies deposited in a shallow lagoon. In these facies, an important microbial contribution and high energy events are recognized; 2) sand bars facies accumulated on the platform margin. Interaction of these facies with sea level fluctuations caused different levels of restriction and periodic flooding in the platform interior; 3) platform margin and fore-reef facies. The microfacies associations of the La Peña Formation were deposited on the periplatform zone in an outer neritic to upper bathyal environment. The microfacies associations of the upper part of the La Peña Formation and those belonging to the Upper Tamaulipas Formation are typical of open marine and relatively deepwater conditions. The microfacies have been divided according to their relation with the different phases of the Cupido Platform drowning. The definitive drowning phase began in the early Aptian when the sea level rose over the sand shoals on the platform margin. An increase in the crinoid content and a mixture of lagoonal and open marine biota are characteristics of the drowning phase at the end of the Cupido Formation deposition. The microfacies associations within the lower part of the La Peña Formation recorded the definitive drowning of the platform and an environmental stress that accentuated this event. Post-drowning facies in the upper part of the La Peña Formation and throughout the Upper Tamaulipas Formation are represented by pelagic facies deposited in an open marine environment with significant oxygen variations in the water-sediment interface. The sand shoals facies described in the Cupido Formation correspond to the western continuation of the Barremian-Aptian Cupido Platform margin.El análisis detallado de microfacies de una sección estratigráfica localizada en el este del estado de Durango aporta importante información paleoambiental y paleogeográfica sobre las plataformas estudiada. La sección estratigráfica comprende el lapso Barremiano-Albiano y está compuesta por la parte superior de la Formación Cupido y las formaciones La Peña y Tamaulipas Superior. El reconocimiento de esta última unidad en el este del estado de Durango es una contribución significativa al esquema estratigráfico de la porción sur de la Sierra del Rosario. El intervalo analizado de la Formación Cupido comprende diferentes asociaciones de microfacies: 1) facies lagunares perimareales y submareales, en algunas de las cuales se reconoce un importante aporte microbiano y facies relacionadas con eventos de alta energía; 2) facies de barras arenosas en la margen de la plataforma, cuya interacción con las fluctuaciones del nivel del mar causaron diferentes niveles de restricción en el interior de la plataforma e inundaciones periódicas; 3) facies de margen de plataforma y del frente arrecifal. Las asociaciones de microfacies de la Formación La Peña fueron depositadas en una posición de periplataforma en la zona nerítica externa a batial superior. Las asociaciones de microfacies de la parte superior de la Formación La Peña y las correspondientes a la Formación Tamaulipas Superior son propias de ambientes marinos abiertos relativamente profundos. A partir de los rasgos de las microfacies se discriminaron las asociaciones relacionadas con cada fase del ahogamiento de la Plataforma Cupido. El ahogamiento definitivo ocurrió a inicios del Aptiano cuando el nivel del mar superó las barras arenosas en la margen de la plataforma. El aumento de crinoideos y la mezcla de biota lagunar y de condiciones marinas abiertas caracterizan la fase de ahogamiento al término del depósito de la Formación Cupido. Las asociaciones de microfacies de la parte inferior de la Formación La Peña denotan el ahogamiento definitivo de la plataforma y registran un estrés ambiental que terminó de acentuar este evento. Las facies posteriores al ahogamiento, en la parte superior de la Formación La Peña y en la Formación Tamaulipas Superior, son facies pelágicas depositadas en una zona con circulación libre al océano abierto y variaciones significativas en el contenido de oxígeno en la interfase sedimento-agua. Las facies de barras arenosas descritas en la Formación Cupido corresponden a la prolongación más al oeste de la margen sur de la Plataforma Cupido durante el Barremiano-Aptiano

Disfunción autonómica y respuesta compensatoria inapropiada de la masa ventricular izquierda en la hipertensión arterial esencial

El objetivo fue investigar si la disfunción autonómica cardiaca (DAC) es un factor determinante de la respuesta compensatoria inapropiada de la masa ventricular izquierda (MVI) en la hipertensión arterial esencial (HTA-E). Se evaluaron 263 pacientes hipertensos mediante ecocardiografía y prueba de esfuerzo. Se definió MVI inapropiada como un índice de respuesta compensatoria de la MVI (IRCMVI) > 128%. Se definió DAC como un índice de deceleración de la frecuencia cardiaca postejercicio (IDFC-postejercicio) ≤ 12 latidos/ minuto. El IRCMVI se correlacionó inversamente con el IDFC-postejercicio (r= - 0.59, p< 0.001). En el análisis multivariante por regresión logística la DAC se comportó como un predictor independiente de MVI inapropiada (odds ratio = 3.4; IC 95%= 1.8 - 6.4; p <0.001). Los resultados de este estudio sugieren que la DAC, caracterizada por disminución de la actividad parasimpática cardiaca e hiperactividad simpática, se relaciona con respuesta compensatoria inapropiada de la MVI en pacientes con HTA-E.The goal of this study was to investigate whether cardiac autonomic dysfunction (CAD) is determinant factor of inappropriate compensatory response of the left ventricular mass (LVM) in patients with essential arterial hypertension. Two hundred and sixty three hypertensive patients were studied by Doppler echocardiography and maximal exercise test. Compensatory response index of left ventricular mass (CRI-LVM) > 128% defined inappropriate LVM. Heart rate recovery index after exercise (HRR index) ≤ 12 beats/min defined CAD. The RI-LVM was inversely correlated with HRR index (r= - 0.59, p< 0.001). A stepwise multivariate logistic regression analysis showed that CAD was independent predictor of inappropriate LVM (odds ratio = 3.4; IC 95%= 1.8 - 6.4; p <0.001). Our results suggested that DAC, characterized by attenuated parasympathetic activity and sympathetic hyperactivity, is related to inappropriate compensatory response of the LVM

Bioevents and redox conditions around the Cenomanian-Turonian anoxic event in Central Mexico

The Xilitla section of central Mexico (western margin of the proto-North Atlantic) is characterized by pelagic sediments enriched in marine organic matter. Using biostratigraphic and radiometric data, it was dated at the latest Cenomanian-earliest Turonian transition. We identified an interval coeval with the faunal turnover associated with the Oceanic Anoxic Event 2 (OAE 2), recording the Heterohelix shift and thePeer Reviewe

Banco didáctico como estrategia de I+D+i en la enseñanza de la mecatrónica

Este proyecto innovación y desarrollo tecnológico busca el diseño de un banco de pruebas modular que ofrezca numerosas ventajas, incluido la reducción de costos y tiempos de desarrollo, la mejora de la calidad y fiabilidad del producto, la oportunidad de aprendizaje para una persona que no cuenta con la suficiente experiencia pudiendo así aprender y entender cómo funcionan los diferentes componentes de control y actuación en un ambiente controlado y de fácil acceso con la posibilidad de realizar pruebas de manera más eficiente y precisa. El banco de pruebas modular para mecatrónica será especialmente útil para la evaluación de sistemas de control de procesos, ya que permite simular diferentes situaciones de operación en un entorno seguro y controlado