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Stromatolites form by the close interaction between the microbial activity and the environment in a great range of depositional settings resulting in heterogeneous growth morphologies and fabrics. The link between morphological diversity and internal structure of stromatolites to environments is not straightforward due to the dual influence at all scales of biological and physico-chemical factors. Specifically, in low energy settings biological controls are the dominant in influencing stromatolites, as suggested from modern analogues.In this study we examine geometries and fabrics of stromatolites from the mixed carbonate-siliciclastic marginal lacustrine succession of the Yacoraite Formation (Cretaceous-Paleogene) in Tres Cruces (Salta Basin). The outcrops that extend along a W-E transect of 10 kilometres, provide exceptional exposure allowing to analyse the geometries and lateral continuity of the stromatolite beds. Current stratigraphic research interprets the Yacoraite succession as a closed, saline lake with two evolutionary stages. The first stage, dominated by carbonate production, represents a shallow-water perennial lake with moderate wave energy. The second stage corresponds to a rapidly fluctuating, low-water energy ephemeral lake with abundant fine-grained siliciclastics and frequent subaerial events. This change is related to climatically driven lake-level fluctuations. Marked differences in the lateral continuity of the stromatolite beds and their associated facies have been observed along the Yacoraite succession. In the perennial lake, the stromatolite beds overlie oolitic facies and can be traced laterally for several kilometres whereas in the ephemeral lake the stromatolites grow on both oolitic and siliciclastic facies and form discontinuous levels along hundreds of meters that pass laterally into the oolitic facies. Stromatolite growth morphologies, however, show a more homogeneous distribution that does not clearly reflect the evolutionary changes of the Yacoraite paleolake. Generally, the stromatolites of the perennial lake exhibit planar morphologies that pass upwards into coalescent domes forming structures that range in height from few decimetres up to 1 m. The stromatolites of the ephemeral lake are mainly planar, wavy (dm-scale) or domes that are coalescent and form tabular decimetric structures. Morphological vertical zonation is rare. The change in stromatolite morphology can be tentatively attributed to decreased accommodation and water energy conditions. However, this interpretation needs to be taken carefully considering that all these types of stromatolite morphologies have been observed along the Yacoraite succession, regardless of the lake stage. Stromatolites show mainly well-developed internal lamination. Their microfabrics are either fine-grained (micritic, clotted and/or filamentous) or formed by combinations of fine-grained and sparry layers composed of fibrous calcite crusts, calcite spherulites and/or shrubs.Further work will intend to better understand the spatial and temporal distribution of the stromatolite geometries and fabrics along the Yacoraite Formation to shed light on the influence that environmental and biotic factors exert in stromatolite macro, meso and microscale in low-energy lacustrine settings.

The interplay between carbonate production and siliciclastic input in marine mixed depositional systems results in spatially complex distribution of facies. In this study, we investigate this interplay in a lacustrine setting to explore hypotheses for the facies distribution and stratigraphic architecture in such settings. The Yacoraite Formation (Maastrichtian-Danian) is a mixed lacustrine carbonate-siliciclastic succession within the Salta Group in the Salta rift Basin (Argentina). The Yacoraite Fm has been thoroughly characterized in the southern part of the basin (Metán-Alemania sub-basins), whereas the northern sub-basin of Tres Cruces, focus of this study, remains largely understudied. In this project we applied high-resolution stratigraphic and sedimentological analyses to characterize in detail the depositional environment and the stratigraphic architecture of the Yacoraite Fm. Facies are mainly represented by lacustrine marginal and littoral associations. The facies associations, their distribution and stacking pattern are interpreted to reflect deposition in a predominantly shallow water balanced-fill lake basin type. Littoral and sub-littoral facies associations are dominated by oolitic, skeletal and microbial carbonates, frequently intercalated with fine-grained siliciclastic facies, ranging from mudstones and siltstones deposited in mudflats, shoreline sandstone deposits and distal profundal shales. The Yacoraite Fm is tentatively subdivided in two intervals. The lower part (lower 100 m) is characterized by carbonate-dominated facies, showing a marked and regular cyclicity, with metric-scale sequences of carbonate-dominated facies overlying fine-grained siliciclastics and mudstone-wackestone. These cycles are interpreted as shallowing-upwards cycles, composing the regressive hemicycles of metric-scale Transgressive-Regressive (T-R) cycles. These cycles are often asymmetric and result from lacustrine expansion-contraction cycles, controlled by climatically influenced lake-level fluctuations. The middle-upper part (m 100 to 220 circa) is dominated by siliciclastic facies and is characterized by a decrease in regularity of cyclicity, with high frequency T-R cycles being asymmetric and often lacking the transgressive hemicycles. Frequent desiccation cracks and tepees mark the top of the regressive hemicycles in the middle to upper part, indicating repeated sub-aerial exposures. Our observations are in line with the hypothesis that alternating phases of deposition between clastic-dominated facies and carbonate-dominated facies are the result of climatically driven lake-level fluctuations. Carbonate production is enhanced during arid climatic phases (lake contraction), whereas siliciclastic-dominated facies are mainly deposited during humid phases, coeval with an increase of water inflow and sediment input into the lake, corresponding to expansion phases. Based on our sedimentological and stratigraphical analysis the evolution of the lake system has been inferred, with the identification of two lake stages in the evolution of the Yacoraite paleo-lake. A first lake stage is characterized by a perennial lake system that progressively changes into a more rapidly fluctuating ephemeral setting; this shift appears to be gradual as there is no clear stratigraphic expression corresponding to the transition itself. Climate appears to be the primary control on the stratigraphic architecture, with rapid lake-level variations resulting in sharp facies transitions from carbonate to siliciclastic facies and prevalently stratigraphic mixing. Compositional mixing is limited to the littoral facies, due to the local presence of siliciclastic input sources by riverine inflows into the Yacoraite paleo-lake system.

The first pre-Quaternary representative of Alismataceae from South America is reported based on achenes of Sagittaria montevidensis from the Palo Pintado Formation (upper Miocene) in the south of Salta Province, Argentina. Achenes are laterally compressed, have a lateral beak and a single recurved seed inside them. The fruits were found both in the base (10 Ma) and the top of the formation (~5 Ma), suggesting similar environmental conditions during this time period. A cursory review of the Alismataceae family in the fossil record, with a special interest in those South American reports is given. During the Oligocene–Miocene Sagittaria may have arrived from tropical Africa to South America and thence to North America.

Blood stasis is the main cause of left atrial thrombosis (LAT) in atrial tachyarrhythmias. The high-velocity flow inside the left atrium, due to mitral valve regurgitation, may prevent clot formation but the topic has never been investigated in large-scale studies. The aim of our study was to evaluate whether the presence and degree of mitral regurgitation have a protective role against LAT risk.A total of 1302 consecutive adult patients with paroxysmal or persistent atrial fibrillation or flutter undergoing cardioversion, submitted to transesophageal echocardiography, were retrospectively enrolled in the study. The study population was divided into three groups according to the mitral regurgitation degree: absent, mild-to-moderate and severe.Among 1302 patients enrolled in the study, patients without mitral regurgitation were 248 (19%), those with mild-to-moderate 970 (75%), whereas 84 had severe mitral regurgitation (6%). LAT incidence was significantly lower in patients with severe mitral regurgitation compared with those with mild-to-moderate (mitral regurgitation) (2.4 vs. 8.9%, P 0.05), and similar to subjects without mitral regurgitation (2.4%).Despite patients with severe regurgitation having clinical and echo characteristics predisposing to LAT (higher age, heart failure, higher atrial size, lower ventricular function) thrombosis prevalence was significantly lower than for those with mild-to-moderate mitral regurgitation. The percentage of LAT in severe mitral regurgitation cases was very low and similar to that of cases without regurgitation which were characterized by lower age, normal left ventricular function or other risk factors, reinforcing the hypothesis of a protecting role against atrial thrombosis of mitral regurgitation.

Las rocas sedimentarias continentales que constituyen la Formación Palo Pintado, de edad del Mioceno tardío, afloran en la provincia de Salta y suscitan un gran interés paleoclimático, dadas las condiciones ambientales reinantes durante ese intervalo geocronológico. Los registros geológicos y paleobotánicos sugieren que durante la acumulación de las rocas sedimentarias de la Formación Palo Pintado (cuenca de Angastaco) habrían existido condiciones más húmedas en comparación a las de otras formaciones cercanas y coetáneas, por ejemplo, la Aloformación Playa del Zorro y la Formación Chiquimil (Mioceno tardío, provincias de Catamarca y Tucumán) y las formaciones Salicas y Toro Negro (Mioceno tardío, provincia de La Rioja). En este estudio se analizaron el margen y el área foliar de las hojas fósiles contenidas en las rocas de la Formación Palo Pintado, a fin de obtener la temperatura media anual (TMA) y la precipitación media anual (PMA). Los valores resultantes fueron los siguientes: TMA=23,98 °C y PMA=330,8 mm. Estos resultados se condicen con la interpretación de diferentes autores quienes consideran que la Formación Palo Pintado se habría depositado bajo un ambiente relativamente húmedo, posiblemente como consecuencia de las lluvias caídas localmente en la región de la cuenca de Angastaco. The continental sedimentary rocks that constitute the Palo Pintado Formation of the late Miocene from Salta province, presents a great paleoclimatic interest due to the environmental conditions prevailing during this geochronologic interval. The geological and paleobotanical data suggest that during the sedimentary rocks accumulation of the Palo Pintado Formation (Angastaco Basin), wetter conditions would have existed comparing with other nearby and contemporary Formations, for example the Playa del Zorro Aloformation (late Miocene of Catamarca) and the Chiquimil (late Miocene of Tucumán), Salicas and the Toro Negro Formations (both from the late Miocene of La Rioja). In this study, the margin and the foliar area of the leaves contained on rocks from the Palo Pintado Formation are analyzed, in order to obtain the mean annual temperature (MAT) and the mean annual precipitation (MAP). The resulting values were: 23.98 °C and 330.8 mm. These results are coincident by the interpretation of different authors, who consider that the Palo Pintado Formation would have been deposited under a relatively humid environment, possibly as a consequence of the rains that affected locally the Angastaco basin region. Fil: Robledo, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina Fil: Horn, Maricel Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina Fil: Galli, Claudia Inés. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: Anzótegui, Luisa Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina

The Ramadas Volcanic Center on the eastern margin of the central Andean Puna plateau along the Olacapato-El Toro lineament in Argentina erupted a rare strongly peraluminous Mn-rich garnet-bearing rhyolitic tuff in the late Miocene. The voluminous ashes from this eruption, which are distinctive in having euhedral spessartine almandine garnets (Alm70–72Sps22–26Grs2–4Prp0.5–1) as their only phenocryst, are widely dispersed in the Andean foreland. Among these tuffs are those in the Guanaco Formation foreland basin sediments along the Xibi-Xibi and Los Alisos rivers in the Rio Grande de Jujuy basin and the Metán Valley, some 100–200 km east of the Ramada Volcanic Center. The co-occurrence of tubular to cellular pumice fragments and blocky glass shards in an ash matrix in these tuffs is interpreted as indicating that they erupted in an initial vent-opening event with pulsating pyroclastic surges at the initiation of the strong Plinian eruption of the Ramada Volcanic Center. New Ar/Ar ages from the Guanaco Fm. glass shards agree with fossil ages in placing the eruption at ~6.3 ± 0.3 Ma. A number of distinctive chemical, isotopic and mineralogical features including Mg-rich biotite and Mg-hastingsite xenocrysts of the Guanaco Formation and Ramadas Volcanic Center tuffs are consistent with the melt having been derived by extensive crystallization of a mantle-derived mafic shoshonitic series magma contaminated by assimilation/dehydration melts of metapelitic sediment and the Puna crust. Distinctive chemical features include whole rock SiO2 contents of ~75–76% wt%; A/CNK indices >1.2; low Ca, Mg, Ti, and Fe concentrations; steep REE patterns with extreme negative Eu anomalies; low Ba, Sr, LREE and high Cs, Rb, U concentrations; and recalculated initial ratios of 87Sr/86Sr at ~0.7119 and 143Nd/144Nd of ~0.5123 at 6.3 Ma. The erupted magma has a transitional chemical character between those of the ~11 Ma Mn-rich garnet-bearing Coyaguayma ignimbrites to the north and the ~6 Ma Cerro Galan ignimbrites to the south. Unlike these crystal-rich ignimbrites, the Ramadas tuff records the extraction of an extensively fractioned melt from a plagioclase, K-feldspar, quartz and biotite-bearing mush with accessory titanomagnetite and apatite. In line with existing experimental studies on Mn-rich garnets and comparisons with the Coyaguayma ignimbrite, pre-eruption crystallization of the rhyolite segregated from the mush likely occurred at ~800° to 720 °C at a depth of no

El presente material es producto de la experiencia en cátedras del área Álgebra y cursos de ingreso y la previa elaboración de apuntes para Álgebra, Cálculo Numérico y Geometría Analítica, Matemática I. Recopila, unifica, amplía y mejora el material existente. Presenta todos los temas de esas asignaturas, con una base teórica sólida, práctica, aplicaciones y motivaciones, integrando y relacionando contenidos. Algunos temas son comunes y de igual nivel en las tres. Otros difieren en profundidad y hay subtemas abordados solo en alguna de ellas. Por ello, sugerimos al estudiante que utilice el libro con diferente recorrido de acuerdo a su interés. Es texto de las materias mencionadas y puede servir de consulta o referencia para las asignaturas Probabilidades, Estadística e inicio para otras del área Álgebra., Facultad de Ciencias Exactas

Quality insurance processes use goal attainment as criteria for funding occupational therapist (OT) services in Switzerland. As this is an important issue for the Swiss OT association, a continuing professional development (CPD) programme was implemented to assist OTs to set occupation-focused and person-centred goals. This qualitative study was conducted using three focus groups to understand the difficulties met by clinicians in the context of setting goals. Sixteen OTs reported that time constraints and routines make it difficult to define and formulate goals well. The problem is not a lack of knowledge, but to change one’s habits and practices the results. A CPD course was developed, adapted in three languages and implemented. Evaluation of the course indicates that it helps the participants to better understand the need for writing goals that are person-centred and occupation-focused. This course may be supportive of improved occupational-based goal setting in other countries.

The radiofrequency maze procedure achieves sinus rhythm in 45%–95% of patients treated for atrial fibrillation. This retrospective study evaluates mid-term results of the radiofrequency maze—performed concomitant to elective cardiac surgery—to determine sinus-rhythm predictive factors, and describes the evolution of patients' echocardiographic variables. From 2003 through 2011, 247 patients (mean age, 64 ± 9.5 yr) with structural heart disease (79.3% mitral disease) and atrial fibrillation underwent a concomitant radiofrequency modified maze procedure. Patients were monitored by 24-hour Holter at 3, 6, 12, and 24 months, then annually. Eighty-four mitral-valve patients underwent regular echocardiographic follow-up. Univariate and multivariate analysis for risk factors of maze failure were identified. The in-hospital mortality rate was 1.2%. During a median follow-up of 39.4 months, the late mortality rate was 3.6%, and pacemaker insertion was necessary in 26 patients (9.4%). Sinus rhythm was present in 63% of patients at the latest follow-up. Predictive factors for atrial fibrillation recurrence were arrhythmia duration (hazard ratio [HR]=1.296, P=0.045) and atrial fibrillation at hospital discharge (HR=2.03, P=0.019). The monopolar device favored maze success (HR=0.191, P Concomitant radiofrequency maze procedure provided remarkable outcomes. Shorter preoperative atrial fibrillation duration, monopolar device use, and prompt treatment of arrhythmia recurrences increase the midterm success rate. Early sinus rhythm restoration seems to result in better left ventricular ejection fraction recovery.

Background. Maze procedure aims at restoring sinus rhythm (SR) and atrial contractility (AC). This study evaluated multiple aspects of AC recovery and their relationship with SR regain after ablation.Methods. 122 mitral and fibrillating patients underwent radiofrequency Maze. Rhythm check and echocardiographic control of biatrial contractility were performed at 3, 6, 12, and 24 months postoperatively. A multivariate Cox analysis of risk factors for absence of AC recuperation was applied.Results. At 2-years follow-up, SR was achieved in 79% of patients. SR-AC coexistence increased from 76% until 98%, while biatrial contraction detection augmented from 84 to 98% at late stage. Shorter preoperative arrhythmia duration was the only common predictor of SR-AC restoring, while pulmonary artery pressure (PAP) negatively influenced AC recuperation. Early AC restoration favored future freedom from arrhythmia recurrence. Minor LA dimensions correlated with improved future A/E value and vice versa. Right atrial (RA) contractility restoring favored better left ventricular (LV) performance and volumes.Conclusions. SR and left AC are two interrelated Maze objectives. Factors associated with arrhythmia “chronic state” (PAP and arrhythmia duration) are negative predictors of procedural success. Our results suggest an association between postoperative LA dimensions and “kick” restoring and an influence of RA contraction onto LV function.