Graptolitos del Tremadociense (Ordovícico Inferior) de la formación Volcancito, Sistema de Famatina (La Rioja, Argentina)

El Miembro Peña Negra de la Formación Volcancito(Tremadociense) del Sistema de Famatina (noroeste argentino) consta de pizarras negras graptolíticas, que se investigaron paleontológicamente, capa a capa, a lo largo de 400 m de sucesión en las secciones complementarias de Peña Negra y río Volcancito, la segunda de las cuales incluye los niveles más modernos. Los resultados bioestratigráficos permiten una correlación precisa con las asociaciones evolutivas y cronozonas globales de graptolitos del Tremadociense, y la reevaluación de todas las dataciones e identificaciones previas de la unidad. Los graptolitos más antiguos se localizan en el Miembro Filo Azul de la formación (Cámbrico Superior-Tremadociense) y se adscriben muy probablemente a la cronozona de Rhabdinopora fl abelliformis parabola de la base del Ordovícico, lo que concuerda con los datos suministrados por los trilobites y conodontos. Las asociaciones graptolíticas de la parte baja del Miembro Peña Negra pertenecen a las cronozonas de Anisograptus matanensis and R. f. anglica, indicativas del Tremadociense superior tardío. Los dos tercios restantes del Miembro Peña Negra se correlacionan probablemente con el Tremadociense superior temprano (cronozona de Adelograptus?), en ausencia de asociaciones batipelágicas típicas con adelográptidos delicados, o formas epipelágicas de aguas cálidas como Psigraptus. Esta posible atribución se apoya también en el registro de conodontos y graptolitos del Tremadociense superior en la Formación Bordo Atravesado suprayacente. Las pizarras negras graptolíticas de la Formación Volcancito se depositaron en fondos anóxicos profundos (de plataforma externa a planicie cuencal) en el margen de Gondwana occidental, previamente al nacimiento y emersión del Arco Volcánico Famatinense. El desarrollo de condiciones anóxicas tuvo que ver con la aparición de un área de afloramiento oceánica con elevada productividad orgánica, que constituyó el hábitat favorable para los rhabdinoporínidos holo- y mesopelágicos, donde se desarrollaron algunas formas endémicas. Desde el punto de vista paleontológico, se identifican y describen Rhabdinopora fl abelliformis fl abelliformis, R. f. anglica, R. f. socialis, R. f. bryograptoides?, R. cf. enigma, Anisograptus matanensis y Bryograptus? sp. La forma Rhabdinopora fl abelliformis famatinensis se propone restringirla al holotipo para obviar su mala caracterización taxonómica. Las nuevas formas Rhabdinopora turneri sp. nov. y R. fl abelliformis acenolazai subsp. nov., guardan ciertas similitudes con los graptolitos planctónicos primitivos R. praeparabola y R. fl abelliformis parabola, respectivamente. Sin embargo, los nuevos taxones del Famatina coexisten en horizontes más modernos de las cronozonas de A. matanensis y R. f. anglica, que claramente postdatan la aparición del desarrollo proximal trirradiado. Además de las formas planctónicas, se describen algunos restos transportados de graptolitos bentónicos como Dendrograptus sp., Dictyonema sp. nov. 1, Aspidograptus cuerdai sp. nov., Pseudocallograptus? sp. y Airograptus? guillermoi sp. nov.. Otro graptolito bentónico notable, Dictyonema? sp. cf. D. cordillerensis, se cita por vez primera en la Formación Bordo Atravesado del Tremadociense superior. [ABSTRACT] Tremadocian graptolites from the Famatina System (NW Argentina) occurred mainly in the black shales that characterized the Peña Negra Member of the Volcancito Formation. Bed-by-bed collecting of graptolites through the 400 m thick sequence of the Peña Negra and Volcancito river sections, resulted in a complete taxonomic and biostratigraphic reappraisal of the abundant graptolite record, which is merited by recent review and correlation of the Tremadocian chronozones and global graptolite assemblages. The two sections are not exactly time equivalent as there were considered largely until the present study, reaching younger beds in Volcancito river. The oldest Ordovician graptolites occur in the upper part of the Filo Azul Member of the Volcancito Formation, with an assemblage probably representative of the Early Tremadocian Rhabdinopora fl abelliformis parabola chronozone, placed slightly above the Cambrian-Ordovician boundary as indicated by trilobite and conodont distributions. Graptolite assemblages from the lower part of the Peña Negra Member of the Volcancito Formation are correlated with the Anisograptus matanensis and R. f. anglica graptolite chronozones of the upper Lower Tremadocian. Above the respective biozones, the remaining upper two thirds of the formation probably correlate with the lowest Upper Tremadocian ?Adelograptus Zone, in absence of batipelagic assemblages of delicate adelograptids or the epipelagic warm-water genus Psigraptus. This data agrees with the occurrence of Upper Tremadocian conodonts and graptolites, namely the Paltodus deltifer conodont biozone and the graptolitic “Assemblage 4”, in the overlying Bordo Atravesado Formation. The black graptolite shales of the Volcancito Formation were deposited under anoxic conditions in an outer shelf to basin plain along the margings of western Gondwana, before the origination and emersion of the Famatinian Volcanic Arch. The anoxic conditions probably developed under a restricted upwelling area with high productivity that was a favourable habitat for some endemic holopelagic and mesopelagic rhabdinoporinids. From a paleontological point of view, the identifi ed and described forms are Rhabdinopora fl abelliformis fl abelliformis, R. f. anglica, R. f. socialis, R. f. ?bryograptoides, R. cf. enigma, Anisograptus matanensis and ?Bryograptus sp. The bad characterized form Rhabdinopora fl abelliformis famatinensis is here restricted to the holotype. Two new taxa, Rhabdinopora turneri sp. nov. and R. fl abelliformis acenolazai subsp. nov., are respectively reminiscent of R. praeparabola and R. f. parabola, both global elements of the earliest Tremadocian graptolite “Assemblage 1”. However the record of the new Famatinian forms, besides different average morphology and measurements, is rather younger and clearly postdate the appearance of rhabdosomes with triradiate development, being distributed in the A. matanensis and R. f. anglica zones. Together with the planktic graptolites, some transported remains of rooted (benthic) dendroids are recorded from some levels and described as Dendrograptus sp., Dictyonema sp. nov. 1, Aspidograptus cuerdai sp. nov., ?Pseudocallograptus sp. and ?Airograptus guillermoi sp. nov.. The fi rst occurrence of a remarkable benthic graptolite (?Dictyonema sp. cf. D. cordillerensis) in the Tremadocian Bordo Atravesado Formation is also reported

Modeling of association effects in mixtures of carboxylic acids with associating and non-associating components

http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=6&SID=V21Di6PajaHLPoM3@AJ&page=1&doc=1&colname=WOSThe group contribution with association equation of state GCA-EOS has been applied to calculate thermodynamic properties of pure compounds and mixtures of carboxylic acids with paraffins, alcohols, water and gases, at low and high pressures. Two associating groups, OH and COOH, were defined. Self- and cross-association in these mixtures were quantified through two parallel COOH/COOH and OH/OH associations. The validity of this approach is supported by an excellent representation of pure compound properties (vapor pressures and compressibility factors) and phase equilibria in mixtures of (associating + inert) and (associating + associating) components at low and high pressures

The extended gca-eos model for mixtures of fatty oils and derivatives

The Group Contribution Equation of State GC-EOS has been satisfactory applied to the modeling of high-pressure phase equilibria of supercritical gases (CO2, propane, ethane, dimethylether) with pure triglycerides and natural vegetable oils. The GC-EOS model size-related parameter, i.e. the critical hard sphere diameter, of the high molecular weight compounds were determined by fitting infinite dilution activity coefficients of n-alkanes in these heavy compounds. In this way the GC-EOS model was able to correlate and predict vapor-liquid (VLE) and liquid-liquid (LLE) equilibria of these mixtures, using a unique set of parameters, in good agreement with experimental data. In this work the application of the model is extended to mixtures containing fatty oil derivatives, such as fatty acids, fatty acids esters, mono - and diglycerides. The associating effects between molecules are described using an upgraded version of the model, the Group Contribution Associating - EOS. Satisfactory correlation and prediction of experimental VLE, LLE and ginfinite data in binary and ternary mixtures of these products with supercritical gases are obtained

Trilobites en facies de lutitas oscuras del Miembro Alfarcito (Formación Santa Rosita, Furongiano alto-Ordovícico Inferior bajo) de la quebrada de Moya, Cordillera Oriental de Jujuy, Argentina

La Formación Santa Rosita (Furongiano tardío - Ordovícico Temprano) presenta una amplia distribución en la Cordillera Oriental del noroeste argentino. Su historia depositacional es compleja ya que incluye episodios transgresivos-regresivos de gran alcance, los cuales generaron una gama diversa de ambientes y facies sedimentarias. La quebrada de Moya constituye una localidad clásica de la unidad en la quebrada de Humahuaca (sierra de Tilcara, Jujuy), en la que se destacan las facies de lutitas oscuras del intervalo superior del Miembro Alfarcito. De estos niveles se describe una fauna de trilobites compuesta por Leptoplastides marianus (Hoek), Angelina? sp., Parabolinella sp. 1, Parabolinella sp. 2, Hapalopleura acantha Malanca y Brandán, Hapalopleura clavata Harrington y Leanza, y Asaphellus sp. Una calcarenita interestratificada en las limolitas contiene los conodontes Teridontus gallicus Serpagli, Ferretti, Nicoll y Serventi, Variabiloconus n. sp., Semiacontiodus minutus Zeballo, Albanesi y Ortega, y Problematoconites perforatus Müller, refiriendo a la Zona de Cordylodus angulatus (Tremadociano inferior). La edad ordovícica temprana está confirmada, además, por el registro del graptolito Rhabdinopora flabelliformis ssp. en una arenisca que subyace a los niveles estudiados. Las pelitas oscuras se acumularon por decantación durante períodos de máxima inundación. Análisis de difracción de rayos X revelaron la presencia de minerales opacos finamente particulados, lo que permite inferir deficiencia de oxígeno en el medio de sedimentación. La fauna de trilobites está dominada por L. marianus, seguida por olénidos bentónicos especialmente adaptados a vivir en condiciones disóxicas (Parabolinella). La morfología de Hapalopleura es interpretada, asimismo, como una adaptación a este último hábito. La parte superior del Miembro Alfarcito no exhibe facies oscuras en otros sectores de la sierra de Tilcara. Las características sedimentológicas de la sección descripta, la baja diversidad de la asociación de conodontes y la ausencia de trilobites agnóstidos podrían indicar condiciones de cierto aislamiento en este sector de la cuenca.Simposio I: 2º Simposio de Bioestratigrafía y Eventos del Paleozoico inferior.Facultad de Ciencias Naturales y Muse

Application of the GCA-EOS model to the supercritical processing of associating oil derivatives: fatty acids, alcohols and triglycerides

Supercritical processes are of interest in the fatty oil industry for a variety of applications: extraction and refining, removal of pollutants, recovery of specialties, hydrogenation of oils and derivatives, etc. Typical process mixtures include heavy compounds and gases at near critical conditions. At high pressures these asymmetric systems present a complex multiphase behaviour, difficult to model. This complexity increases if some of the mixture components are able to self- and/or cross associate. In the present work, the group contribution with association equation of state (GCA-EoS) [3] is extended to represent high pressure phase equilibria in mixtures of supercritical gases (carbon dioxide, propane, ethane) with fatty oil derivatives, such as mono- and di-glycerides, fatty acids, alcohols, water and esters. Self- and cross association between associating groups present in these mixtures are considered. Satisfactory correlation and prediction of equilibrium data are obtained. The capacity of the model to follow the behaviour of solutions towards the limit of infinite dilution of the associating components is of particular importance

Extension of UNIFAC to associating systems

An extended UNIFAC group contribution model for the prediction of activity coefficients in associating mixtures was presented recently (Mengarelli et al.,1999). In the present work the model is applied to solutions containing alcohols, water, carboxylic acids and inert components. The residual UNIFAC local composition term is re-parameterized in order to take into account only dispersive forces between associating and inert functional groups. Good representation of vapor-liquid and liquid-liquid equilibrium, as well as infinite dilution activity coefficients is achieved by using a single set of group interaction parameters

Lifestyle in Undergraduate Students and Demographically Matched Controls during the COVID-19 Pandemic in Spain

Few studies have used a multidimensional approach to describe lifestyle changes among undergraduate students during the COVID-19 pandemic or have included controls. This study aimed to evaluate lifestyle behaviors and mental health of undergraduate students and compare them with an age and sex-matched control group. A cross-sectional web survey using snowball sampling was conducted several months after the beginning of COVID-19 pandemic in Spain. A sample of 221 students was recruited. The main outcome was the total SMILE-C score. Students showed a better SMILE-C score than controls (79.8 + 8.1 vs. 77.2 + 8.3; p < 0.001), although these differences disappeared after controlling for covariates. While groups did not differ in the screenings of depression and alcohol abuse, students reported lower rates of anxiety (28.5% vs. 37.1%; p = 0.042). A lower number of cohabitants, poorer self-perceived health and positive screening for depression and anxiety, or for depression only were independently associated (p < 0.05) with unhealthier lifestyles in both groups. History of mental illness and financial difficulties were predictors of unhealthier lifestyles for students, whereas totally/moderate changes in substance abuse and stress management (p < 0.05) were predictors for the members of the control group. Several months after the pandemic, undergraduate students and other young adults had similar lifestyles

Timber production and biodiversity conservation in Nothofagus forests of Tierra del Fuego and southern Patagonia.

Las propuestas de manejo forestal para Tierra del Fuego y Patagonia Sur se basan en el manejo silvopastoril para Nothofagus antarctica (ñire), y cortas de protección y raleo para Nothofagus pumilio (lenga). Ambas propuestas producen impactos sobre los componentes bióticos y abióticos del bosque original. El objetivo de este capítulo es analizar las propuestas de manejo, planteando alternativas que prioricen el equilibrio entre producción y conservación a partir de las investigaciones actuales. Se analizan diferentes escalas en la planificación del manejo forestal y estrategias de conservación (macro, meso y micro-escala), describiendo ventajas y costos incrementales de su aplicación. En particular, se describe la aplicación de la retención variable como técnica complementaria de las cortas de protección, para minimizar los impactos de la cosecha a escala de rodal sobre las variables abióticas y bióticas. Asimismo, se analiza la regeneración natural como la variable de mayor importancia en los monitoreos postcosecha, junto con los factores limitantes del ciclo y la posterior dinámica en parcelas de investigación a largo plazo, así como los resultados de ensayos de raleos y podas comerciales. Finalmente, se describen las carencias en el conocimiento científico y técnico desarrollado hasta el presente, a fin de mejorar la implementación del manejo forestal actual. A partir de este análisis se proponen diez desafíos a tener en cuenta para la próxima década. Summary: Forest management for Tierra del Fuego and southern Patagonia are based mainly on silvopastoral use of Nothofagus antarctica (ñire), and shelterwood cuts and thinnings for Nothofagus pumilio (lenga). Both proposals had impacts over biotic and abiotic components of the original forests. The objective of this chapter was to analyze these management practices by introducing a concept of equilibrium between timber production and conservation. Different planning scales (macro-, meso- and micro-scale) were analyzed for forest management and conservation including advantages and implementation. In particular, variable retention implementation was described as complementary technique of the shelterwood cuts, where harvesting impacts over abiotic and biotic scale at stand level were minimized. Natural regeneration, as one of the most important variable in the post-harvesting monitoring, also was analyzed. Limiting factors in the whole reproductive cycle, their natural dynamics in long-term research plots, commercial thinnings and prunings were described. Finally, it was identified the main actual scientific and technical knowledge gaps in order to improve the future research and implementation in the current forest management.Forest management for Tierra del Fuego and southern Patagonia are based mainly on silvopastoral use of Nothofagus antarctica (ñire), and shelterwood cuts and thinnings for Nothofagus pumilio (lenga). Both proposals had impacts over biotic and abiotic components of the original forests. The objective of this chapter was to analyze these management practices by introducing a concept of equilibrium between timber production and conservation. Different planning scales (macro-, meso- and micro-scale) were analyzed for forest management and conservation including advantages and implementation. In particular, variable retention implementation was described as complementary technique of the shelterwood cuts, where harvesting impacts over abiotic and biotic scale at stand level were minimized. Natural regeneration, as one of the most important variable in the post-harvesting monitoring, also was analyzed. Limiting factors in the whole reproductive cycle, their natural dynamics in long-term research plots, commercial thinnings and prunings were described. Finally, it was identified the main actual scientific and technical knowledge gaps in order to improve the future research and implementation in the current forest management.EEA Santa CruzFil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC); Argentina.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Lencinas, María Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC); Argentina.Fil: Cellini, Juan Manuel. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Investigaciones en Maderas; Argentina.Fil: Barrera, Marcelo Daniel. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Investigaciones en Maderas; Argentina.Fil: Soler Esteban, Rosina Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC); Argentina.Fil: Ivancich, Horacio Simón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC); Argentina.Fil: Mestre, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC); Argentina.Fil: Moretto, Alicia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina.Fil: Anderson, Christopher B. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Anderson, Christopher B. Universidad Nacional de Tierra del Fuego; Argentina.Fil: Pulido, Fernando. Universidad de Extremadura. EUIT Forestal. Forest Research Group; España

Small bowel enteroscopy - A joint clinical guideline from the spanish and portuguese small bowel study groups

The present evidence-based guidelines are focused on the use of device-assisted enteroscopy in the management of small-bowel diseases. A panel of experts selected by the Spanish and Portuguese small bowel study groups reviewed the available evidence focusing on the main indications of this technique, its role in the management algorithm of each indication and on its diagnostic and therapeutic yields. A set of recommendations were issued accordingly.Estas recomendações baseadas na evidência detalham o uso da enteroscopia assistida por dispositivo no manejo clínico das doenças do intestino delgado. Um conjunto de Gastrenterologistas diferenciados em patologia do intestino delgado foi selecionado pelos grupos de estudos Espanhol e Português de intestino delgado para rever a evidência disponível sobre as principais indicações desta técnica, o seu papel nos algoritmos de manejo de cada indicação e sobre o seu rendimento diagnóstico e terapêutico. Foi gerado um conjunto de recomendações pelos autores