Key to cranial and mandibular remains of non-flying small mammals from southern South America Udrizar Sauthier, Daniel Edgardo; Formoso, Anahí Elizabeth; Andrade, Analia; Podestá, Darío; Teta, Pablo Vicente Reliable identification of small mammal bone remains is crucial for several disciplines, including archaeology, biogeography, ecology, paleontology, taxonomy, and taphonomy. However, this issue is usually a challenging task, often complicated by the fragmentary nature of bone accumulations and/or by the taphonomic processes involved in the genesis of some assemblages. In this work, we provide dichotomous artificial keys for crania and mandibles of non-flying small mammal (<1000 g) genera of southern South America (i.e., southern Argentina and Chile). Keys are complemented with separate accounts for species identification, based on the cranial and dental features better preserved on fragmentary materials.

Plant oil-based waterborne polyurethanes: A brief review Mucci, Veronica Lujan; Hormaiztegui, M. E. Victoria; Aranguren, Mirta Ines The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers, whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable, has prompted the efforts to find suitable bio-based sources for the production of polymers. Vegetable oils have been a frequently spotted in this search because they are versatile, highly available and a low cost liquid biosource, which can be used in the synthesis of a wide plethora of different polymers and reactive monomers. Following the same idea of reducing the environmental stress, the traditional polyurethanes that are soluble in organic solvents have been targeted for replacement, particu-larly in applications such as adhesives and coatings, in which the solvent is released to the atmosphere increasing the air pollution. Instead, waterborne poly-urethanes (WBPU), which are polyurethane dispersions (PUD) prepared in aqueous media, release benign water to the atmosphere during use as supported or self-standing films for different applications. In this brief review, the contributions to the development of WBPUs based on vegetable oils are discussed, focusing mainly on the contributions of the last decade. The synthesis of ionic and non-ionic PUDs, their characterization and the properties of the resulting dried mate-rials, as well as derived composite materials are considered.

Temperature Stable Dielectric Properties in BaTiO3–Bi(Mg2/3Nb1/3)O3–NaNbO3 Solid Solution Raz, Muhammad; Ali, Asif; Camargo, Javier Eduardo; Castro, Miriam Susana 0.5BaTiO3–(0.5–x)Bi(Mg2/3Nb1/3)O3–xNaNbO3 (x=0.1, 0.2 and 0.3) samples were processed via solid-state sintering route. Phase identification of the samples showed the formation of a single-phase cubic perovskite-structure (space group Pm-3 m) which was further confirmed using Raman spectroscopy. Microstructural analysis of the samples revealed some voids in the samples while grain size was observed to decrease with increasing NaNbO3 concentration. The addition of NaNbO3 shifted Tm to below room temperature and the stability range of 0.5BaTiO3–0.5Bi(Mg2/3Nb1/3)O3 ceramics was enhanced. The sample with x=0.20 exhibited ϵr(mid) = 400 ±15% stable over a wide temperature range from −85 to 500 °C and most importantly a low dielectric loss of < 0.05 stable across a wide temperature range −100 to 426 °C was maintained. The thermally stable dielectric properties of sample x=0.2 suggests that it could be useful candidate material for capacitor applications in both low (X9R) as well as harsh environment applications.

Ureide permease 5 (AtUPS5) connects cell compartments involved in UREIDE metabolism Lescano López, Ignacio; Bogino, María Florencia; Martini, Carolina; Tessi, Tomás María; González, Claudio Alejandro; Schumacher, Karin; Desimone, Marcelo Allantoin is a purine oxidative product involved in long distance transport of organic nitrogen in nodulating legumes and was recently shown to play a role in stress tolerance in other plants. The subcellular localization of enzymes that catalyze allantoin synthesis and degradation indicates that allantoin is produced in peroxisomes and degraded in the endoplasmic reticulum (ER). Although it has been determined that allantoin is mostly synthesized in roots and transported to shoots either for organic nitrogen translocation in legumes or for plant protection during stress in Arabidopsis (Arabidopsis thaliana), the mechanism and molecular components of allantoin export from root cells are still unknown. AtUPS5 (Arabidopsis UREIDE PERMEASE 5) is a transmembrane protein that transports allantoin with high affinity when expressed in yeast. The subcellular fate of splicing variants AtUPS5L (long) and AtUPS5S (short) was studied by tagging them with fluorescent proteins in their cytosolic loops. The capability of these fusion proteins to complement the function of the native proteins was demonstrated by nutritional and salt stress experiments. Both variants localized to the ER, but the AtUPS5L variant was also detected in the trans-Golgi network/early endosome and at the plasma membrane. AtUPS5L and AtUPS5S localization indicates that they could have different roles in allantoin distribution between subcellular compartments. Our data suggest that under nonstress conditions UPS5L and UPS5S may function in allantoin degradation for nutrient recycling, whereas under stress, both genes may be involved in vesicular export allowing allantoin translocation from roots to shoots.

Checklist of the nematode parasites of wild birds of Argentina Drago, Fabiana Beatriz; Nuñez, Maria Veronica; Dueñas Díaz, Mariano A commented checklist of the nematodes parasites of Argentinean wild birds is presented. This is the first compilation of parasitological papers about nematodes of Argentinean birds published between 1873 and November 2019. This review includes information about 64 nematode nominal species and 13 taxa identified at generic level, belonging to five orders, 16 superfamilies, 20 families, and 44 genera. Five species were considered incertae sedis, because they were described based only on larval stages, and one species was maintained as species inquirenda. The highest number of taxa of nematodes was recorded in the family Acuariidae with 20 nominal species and two taxa identified at generic level, followed by Anisakidae with eight nominal species and one taxon identified at generic level, and Tetrarneridae with eight nominal species and two taxa identified at generic level. Of the 1042 species of birds reported in Argentina, only 65 (6.24%) were reported as hosts of adult nematodes. The families of birds with the highest number of reported taxa were Tinamidae (12 nematode taxa), Laridae (11), Anatidae (8) and Phalacrocoracidae (7). The present review provides data on hosts, geographical distribution, sites of infection, location of material deposited in Helminthologicaj Collections, references, and taxonomic comments. A host/parasite list is also provided.

El estatuto de lo valorativo en psicoanálisis: Aproximaciones entre el psicoanálisis argentino y el feminismo (1983-1995); The status of values in psychoanalysis: Approaches between argentine psychoanalysis and feminism (1983-1995) Gonzalez Oddera, Mariela En el presente artículo se reflexiona sobre el estatuto de la dimensión valorativa en psicoanálisis, desde los aportes de la historia de la psicología, en particular, de la historia crítica. Por un lado, se ubica brevemente la contribución de la epistemología feminista a la consideración de la relación entre valores y ciencia. Luego, se analiza el caso concreto de recepción de los Estudios de la Mujer en la psicología y el psicoanálisis argentino y su proyecto de reflexión crítica sobre los sesgos ideológicos presentes en la empresa freudiana. Al final, se plasma la interrogación por las potencialidades y límites de dicho proyecto.; This article reflects on the status of values in psychoanalysis, trough the contributions of the history of psychology, in particular, the critical history. The contribution of feminist epistemology to the evaluation of the relationship between values and science is briefly included. Then, it´s analized the reception of Women's Studies in the argentine psychology and psychoanalysis, and its project of critical reflection on the ideological biases present in the freudian work. Finally, the potential and limits of this project is boarded.

Evaluation of errors in the distribution system and control of drugs: The case of a private hospital Diaz, Lourdes; Maidana, Mabel; Marin, Lupe; Samaniego, Lourdes; Maciel, Olga; Vera, Zully; Lugo, Gladys; Marin, Gustavo Horacio Introduction: Medication errors may arise during the process of prescribing, transcribing, dispensing, preparation, and administration of any drug. The objective of this study was to quantify the detectable incidence of medication errors that occur in the distribution system and control of drugs administration. Methods: A descriptive non-experimental crosssectional investigation was performed. The data collection instrument consisted on a system of voluntary and anonymous reporting methods. Results: The particularity of the study was that of the total number of tickets under study, only 25 had errors (0.56%). The error incidence rate obtained in this institution result much lower than a previous study conducted by us, in the subsector of Social Security of Paraguay (6.3% vs. 0.56%). The most prevalent error was due to incorrect business name (64%), while the one with the lowest prevalence was referred to the wrong patient and medication unsolicited (4%). Most of the errors detected occurred during transcription (56%). 80% of the errors were detected by pharmacy technicians, 12% bynurses, and 8% by attendees. The particular organization of the hospital and the control carried out in different instances keep a relatively low level of medication errors. The consequences of the errors and the importance of the pharmacist’s role in the detection, prevention, and resolution of these problems were crucial factors in the case studied. Conclusion: Determining the incidence and type of medication error in the different parts of an interaction chain process, allows to analyze its causes, and to make changes where these errors are detected, in order to provide the users of the health system a better care service. Since the commitment of the different health actors involved is decisive to avoid medical errors, it is important to encourage them to support surveillance actions to strengthen good prescription practices.

Estimations of rooting depths and sources of plant-available water (PAW) in flatland petrocalcic soils under different land uses Mujica, Claudio Ramon; Bea, Sergio Andrés Plant-available water (PAW) is one of the most important issues in productive landscapes around the world. Besides climatic conditions, it depends on several factors, among them, land uses, the rooting and water table depths, and the presence of soil heterogeneities (e.g., petrocalcic horizons). In the present work, PAW evolution was assessed over 441 days in a vertical 1D domain of a monitored Pampean petrocalcic soil under two different land uses and contrasted water demand (i.e., natural and afforested grasslands). For this purpose, rooting depths were estimated using a process-based numerical model of the aquifer-soil-plant-atmosphere continuum constrained by both in situ measured atmospheric demand and water table fluctuations. This model was calibrated against soil water content measurements at different depths and finally, as validation, computed transpiration rates were compared with the sap flow measurements. Modeling results, and calibrated rooting depths, suggest that petrocalcic horizons induce a limited hydraulic connection between the shallow soil portions and the phreatic aquifer. Thus, water storage is enhanced above the petrocalcic horizon in the natural grassland plot particularly during the periods of low atmospheric demand, whereas it is immediately consumed by forest to soil wilting point below the afforested grassland (hydric stress). The numerical methodology followed here appears as an alternative to estimate the forest groundwater usage in afforested grasslands, a key issue in soil salinization research in great plain areas.

Análisis espacial de la seropositividad de leptospirosis humana en un espacio rururbano del partido de Tandil mediante Sistemas de Información Geográfica Silva, Julia Analia; Rivero, Mariana Alejandra; Scialfa, Exequiel Alejandro; Linares, Santiago La leptospirosis es la zoonosis de mayor distribución mundial, endémica en Argentina. Las herramientas de análisis espacial contenidas en los Sistemas de Información Geográfica permiten evaluar las correlaciones entre determinantes socioeconómicos y ambientales de la leptospirosis, conocer sus posibles causas y tomar decisiones aplicables en base a información precisa y confiable. En este trabajo se tomó como caso de estudio la localidad de María Ignacia Vela, en el partido de Tandil, la cual presenta una dinámica social y configuración territorial con estrecha vinculación rural y urbana. El trabajo persiguió dos objetivos, en primera instancia, detectar la existencia de patrones de distribución espacial de la seropositividad a leptospirosis y en segundo lugar, modelar un escenario predictivo de la probabilidad de infección por Leptospira spp. en el área de estudio. Para detectar positividad a Leptospira spp. se realizó el diagnóstico serológico a través de la técnica de microaglutinación (MAT). Con los resultados de laboratorio, la información obtenida a partir de encuestas y la georreferencia de los participantes se aplicaron técnicas de análisis estadísticos y espaciales aplicando los softwares EpiInfo versión 3.5.3, InfoStat versión 2018 y ArcGIS 10.6. Las relaciones espaciales halladas entre los determinantes estudiados y la seropositividad a Leptospira spp. facilitarán la definición de estrategias específicas que contribuyan a mejorar la toma de decisiones territoriales en cuestiones de salud en las áreas rururbanas.

Deficiency of CD73 activity promotes protective cardiac immunity against Trypanosoma cruzi infection but permissive environment in visceral adipose tissue Eberhardt, Natalia; Sanmarco, Liliana Maria; Bergero, Gastón; Theumer, Martín Gustavo; García, Mónica Cristina; Ponce, Nicolás Eric; Cano, Roxana Carolina; Aoki, Maria del Pilar Damaged cells release the pro-inflammatory signal ATP, which is degraded by the ectonucleotidases CD39 and CD73 to the anti-inflammatory mediator adenosine (ADO). The balance between ATP/ADO is known to determine the outcome of inflammation/infection. However, modulation of the local immune response in different tissues due to changes in the balance of purinergic metabolites has yet to be investigated. Here, we explored the contribution of CD73-derived ADO on the acute immune response against Trypanosoma cruzi parasite, which invades and proliferates within different target tissues. Deficiency of CD73 activity led to an enhanced cardiac microbicidal immune response with an augmented frequency of macrophages with inflammatory phenotype and increased CD8+ T cell effector functions. The increment of local inducible nitric oxide (NO) synthase (iNOS)+ macrophages and the consequent rise of myocardial NO production in association with reduced ADO levels induced protection against T. cruzi infection as observed by the diminished cardiac parasite burden compared to their wild-type (WT) counterpart. Unexpectedly, parasitemia was substantially raised in CD73KO mice in comparison with WT mice, suggesting the existence of tissue reservoir/s outside myocardium. Indeed, CD73KO liver and visceral adipose tissue (VAT) showed increased parasite burden associated with a reduced ATP/ADO ratio and the lack of substantial microbicidal immune response. These data reveal that the purinergic system has a tissue-dependent impact on the host immune response against T. cruzi infection.

Exploring the use of nuclear alterations, motility and ecological guilds in epipelic diatoms as biomonitoring tools for water quality improvement in urban impacted lowland streams Nicolosi Gelis, María Mercedes; Cochero, Joaquin; Donadelli, Jorge Luis; Gomez, Nora In this study we explored the use of less conventional diatom metrics (motility, nuclear abnormalities and ecological guilds) to measure changes in diatom assemblages related to the transfer of epipelic communities from urban impacted streams to less impacted sites. Three lowland streams in the Argentine Pampean plain were selected, and two sites were established per stream for a total of six sites. Three sites were referenced as low urban impact (LI), as they run through peri-urban areas, and three downstream sites were referenced as high impact sites (HI), since they run through a dense urban area. Six germination trays filled with stream sediment were placed at each HI site, and three at each LI site, and left to be colonized for 30 days before transferring three trays from the HI sites to their respective LI site upstream. Samples were collected at days 0, 15, 30 and 45 days from each tray, and diatom species were identified and classified into ecological guilds. Motility variables were measure per individual of the genera Nitzschia (path length, velocity and maximum velocity) through video recording. Also, the frequency of abnormal nuclear locations and nuclear membrane breakage were determined. Results showed that there were no significant differences in any motility metrics, while the nuclei variables exhibited higher proportion of abnormally positioned nuclei and nuclear membrane breakage at the HI sites. The proportion of nuclear membrane breakage decreased over time in the translocated assemblage, indicating that it could be a sensitive indicator of water quality improvement, while the ecological guilds showed significant differences on the proportion of high profile and motile diatoms. The improvement in water quality produced a significative increase in the proportion of the high profile guild in the translocated biofilm. Despite the motile forms being the dominant group, the water quality improvement allowed the high profile forms, to colonize the substrate. These results emphasize the possible use of the ecological guilds as a suitable indicator of water quality improvement in Pampean streams, especially in nutrient rich environment. These tools can provide a rapid assessment of diatom condition and could be considered supplementary to biomonitoring protocols in lowland streams.

Photo-double-ionization of water at 20 eV above threshold Randazzo, Juan Martin; Turri, G.; Bolognesi, P.; Mathis, J.; Ancarani, L. U.; Avaldi, L. The photodouble ionization of the water molecule is studied at 20 eV excess energy in a combined experimental and theoretical investigation. In the experiments, two photoelectrons of equal kinetic energy are detected in coincidence after energy and angular selection. On the theoretical side, a generalized Sturmian function approach is implemented to describe accurately the correlated two-electron continuum, while separable products of Moccia orbitals [J. Chem. Phys. 40, 2164 (1964)JCPSA60021-960610.1063/1.1725489] are used for the initial electronic state of the water molecule. The theoretical triple-differential cross sections (TDCSs) are averaged over all possible molecular orientations in order to be compared with the experiments. The measured TDCSs display rich angular distributions that are in large part well reproduced by the adopted first-order treatment of the interaction with a two-active-electron target.

Geo-climatic hazards in the eastern subtropical Andes: Distribution, Climate Drivers and Trends Vergara Dal Pont, Iván Pablo; Moreiras, Stella Maris; Araneo, Diego Christian; Garreaud, René Detecting and understanding historical changes in the frequency of geo-climatic hazards (G-CHs) is crucial for the quantification of current hazards and project them into the future. Here we focus in the eastern subtropical Andes (32-33° S), using meteorological data and a century-long inventory of 553 G-CHs triggered by rainfall or snowfall. We first analyse their spatio-temporal distributions and the role of climate variability on the year-to-year changes in the number of days per season with G-CHs. Precipitation is positively correlated with the number of G-CHs across the region and year-round; mean temperature is negatively correlated with snowfall-driven hazards in the western (higher) half of the study region during winter and with rainfall-driven hazards in the eastern zone during summer. The trends of the G-CHs frequency since the mid-20th century were calculated taking cautions for their non-systematic monitoring. The G-CHs series for the different triggers, zones and seasons were generally stationary. Nonetheless, there is a small positive trend in rainfall-driven G-CHs in the eastern zone during summer congruent with a rainfall increase there. We also found a decrease in snowfall-driven G-CHs in the western zone since the late 1990?s onwards, most likely due to a reduction in winter precipitation rather than to an increase in temperature.

Trophic interactions and isotopic niche of octopuses and sea stars in North Patagonia Storero, Lorena Pia; Ocampo Reinaldo, Matías; Narvarte, Maite Andrea; Iribarne, Oscar Osvaldo; Botto, Florencia Coexistence of species is associated with differentiation of niches and partitioning of resources, which lessen niche overlap and the intensity of competition. Here, we used stable isotope analysis to evaluate and compare the trophic relationships and isotopic niche of two coexisting predators, the small octopus Octopus tehuelchus (d’Orbigny 1834) and the brooding sea star Anasterias antarctica (Lütken 1857), in the rocky intertidal community of northern Patagonia (Argentina). Our results show differences in the proportional contribution of sources between octopuses and sea stars. Octopuses consume mainly sessile filter-feeders, and sea stars show intra-specific diet differences, changing its preference with size and sex. Small and medium sea stars feed on sessile filter-feeders, such as small mussels, while large sea stars consume more frequently grazer gastropods and scavenger crustaceans. In the food web of the rocky north Patagonian ecosystem, differences in the isotopic niche space and the degree of dietary specialization between octopuses and sea stars indicate differential use of resources and trophic niche partitioning, possibly by limiting inter- and intra-specific competition.

Expression of IL-33 Receptor Is Significantly Up-Regulated in B Cells During Pregnancy and in the Acute Phase of Preterm Birth in Mice Valeff, Natalin Jimena; Juriol, Lorena Vanesa; Quadrana, Florencia; Muzzio, Damián Oscar; Zygmunt, Marek; Quiroga, María Florencia; Ventimiglia, María Silvia; Jensen, Cristian Federico Interleukin-33 (IL-33) is a mucosal alarmin belonging to the IL-1 cytokine family and is now recognized to have a key role in innate and adaptive immunity, contributing to tissue homeostasis and response to environmental stresses. In addition, IL-33 has also been shown to work as a positive regulator that initiates and maintains a Th2 immune response. In the context of pregnancy, it has been recently demonstrated that upon certain stress conditions, such as an infection induced inflammation, IL-33 is released from the uterine mucosa and triggers decidual B cells to produce anti-inflammatory molecules, which in turn restore immune homeostasis and prevents the development of preterm birth. In this study we therefore performed a detailed characterization of IL-33 receptor (Il1rl1 or ST2) expression in B cells during normal pregnancy, as well as in a mouse model of preterm birth. We observed that splenic B cells significantly up-regulate the expression of Il1rl1 during pregnancy and identified the B1 B cell population as the main ST2-expressing B cell subset. A further kinetic analysis showed that percentages of ST2-expressing B1 B cells are significantly augmented on days 12 and 14 of pregnancy, both in the spleen and peritoneal cavity of pregnant mice, and then drop toward the end of pregnancy to the levels observed in non-pregnant animals. Furthermore, using a mouse model of LPS-induced preterm birth, we demonstrated that not only are the percentages of ST2-expressing B1 B cells significantly enlarged in the spleen during the acute phase of preterm birth, but decidual B cells also significantly up-regulate ST2 expression as compared to term-pregnant mice. Overall, our results suggest a functional role of ST2 expression in B cells during pregnancy and reinforce the importance of the IL-33/ST2 axis in B cells as a critical mechanism to control inflammation-induced preterm birth.

Successful field performance in dry-warm environments of soybean expressing the sunflower transcription factor HaHB4 Ribichich, Karina Fabiana; Chiozza, Mariana; Ávalos-Britez, Selva; Cabello, Julieta Virginia; Arce, Agustín Lucas; Watson, Geronimo; Arias, Claudia Vanina; Portapila, Margarita Isabel; Trucco, Federico; Otegui, Maria Elena; Chan, Raquel Lia Soybean yield is limited primarily by abiotic constraints. No transgenic soybean with improved abiotic-stress tolerance is available in the market. We transformed soybean plants with genetic constructs able to express the sunflower transcription factor HaHB4, which confers drought tolerance to Arabidopsis and wheat plants. One line (b10H) carrying the sunflower promoter was chosen among three independent lines because it exhibited the best performance in seed yield (SY). Such line was evaluated in the greenhouse and in twenty-seven field trials developed in different environments of Argentina. In greenhouse experiments, transgenic plants showed increased SY under stress conditions together with wider epycotyl diameter, enlarged xylem area and enhanced water use efficiency than controls. They also exhibited enhanced SY in warm-dry field conditions. This response was accompanied by the increased in seed number that was not compensated by the decreased in individual seed weight. The transcriptome analysis of plants from a field trial with maximum SY difference between genotypes indicated an induction of genes encoding redox and heat shock proteins in b10H. Collectively, our results indicate that soybeans transformed with HaHB4 are expected to have reduced SY penalization when cropped in warm-dry conditions, which constitute the best target environments for this technology.

Multiorbital electronic correlation effects of Co adatoms on graphene: An ionic Hamiltonian approach Tacca, Marcos Sebastian; Jacob, T.; Goldberg, Edith Catalina In the present work, we propose an ionic Hamiltonian for describing the interaction of graphene with an adsorbed Co atom. In this approach, the electronic correlation effects, related to the many d orbitals involved in the interaction, are taken into account by selecting appropriate electronic configurations of the adsorbed atom. The Hamiltonian parameters are calculated considering the localized and extended features of the atom-surface interacting system. The physical quantities of interest are calculated by using a Green functions formalism, solved by means of the equations of motion method closed up to a second order in the atom-band coupling term. The charge and spin fluctuations in the adsorbed Co atom are inferred from density functional theory calculations and assuming that the lower energy configurations obey Hund?s rules. The calculated spectral densities and the occurrence probabilities of the different atomic configurations are analyzed as a function of the Co energy level positions and the surface temperature. In addition, the conductance spectra are calculated by using the Keldysh formalism and compared with existing measurements. We analyze the behavior, under variable bias and gate potentials, of resonancelike features in the conductance spectra which can be related to transitions between atomic configurations of low occurrence probability.

Morfometría y morfogénesis de tafoni en la Brecha Cerro Colorado, Sierras Australes de la provincia de Buenos Aires: su vinculación con la distribución de espeleotemas silíceos; Morphometry and morphogenesis of tafoni in the Brecha Cerro Colorado, Sierras Australes of the Buenos Aires Province: its relationship with the distribution of siliceous speleothems Lebinson, Fernando Oscar; Grill, Silvia Cristina; Fernandez, Ana Laura; Venega, Enzo Con la finalidad de efectuar un aporte al proceso de tafonización de la Brecha Cerro Colorado (Sierras Australes de Buenos Aires, Argentina) se realizó el análisis morfométrico y morfogenético de 56 tafoni mediante técnicas estadísticas. El estudio incluyó: ancho (x), profundidad (z), altura (y), orientación de los tafoni (o) y presencia / ausencia de espeleotemas silíceos (e). El análisis cluster permitió agruparlos en seis clases: A, B, C, D, E y F. Los tafoni clases A, B, C y D (27), ubicados en sectores más sombríos y húmedos del cerro, presentan el mayor tamaño, formas elipsoidales y una relación x > z > y, donde el 63% de ellos desarrollaron espeleotemas silíceos. Los tafoni más pequeños, clase E (28), registraron una relación x > z ≈ y con una distribución aleatoria en el cerro, donde solamente el 18% de ellos presentó espeleotemas. Un único tafone, clase F, situado en el sector O del cerro, presentó una relación z > x > y, y no se registró espeleotema. El análisis de Componentes Principales ratificó la diferenciación por tamaño de los tafoni (CP1), y vinculo las orientaciones preferenciales de los mismos con la presencia o ausencia de espeleotemas (CP2 y CP3). Los tafoni relevados estuvieron asociados a algún tipo de fractura presente en el cerro, las orientaciones más recurrentes fueron NO-SE, NE-SO, N-S y en menor medida O-E. Este fracturamiento y la disposición del cerro, la estratificación y las características petrológicas de la brecha, habrían favorecido el desarrollo de los tafoni.; The aim of this article is to contribute to the knowledge of the tafoni weathering process of the Brecha Cerro Colorado (Sierras Australes of Buenos Aires Province), throughout a morphometric and morphogenetic analysis of 56 tafoni using statistical techniques. The study included: width (x), depth (z), height (y), tafoni orientation (o) and presence/absence of siliceous speleothems (e). A cluster analysis allowed grouping them into six classes: A, B, C, D, E and F. The tafoni classes A, B, C and D (27) are located in the most humid and shady areas of the hill. They have the largest size, ellipsoidal forms with a relation x> z> y and 63% of them developed siliceous speleothems. The smallest tafoni, class E (28), showed a relationship x> z ≈ y with a random distribution on the hill, and an 18 % of them have speleothems. A single tafone without speleothem formation (class F) located in the western sector of the hill, presented a relation z> x> y. The principal components analysis allowed to differentiate the tafoni by size (1PC), and to relate preferential tafoni orientations with the presence or absence of speleothems (2PC and 3PC). Most of the tafoni surveyed in the breccia were associated with some type of fractures present in the hill, with the most recurrent fractures being the NW-SE, NE-SW, N-S and to a lesser extent W-E. This fracturing, the arrangement of the hill, and the bedding and petrological characteristics of the Brecha Cerro Colorado, would have favoured the development of tafoni.

Evaluación de la capacidad de sellado de MTA,IVyOZE en retrobturación apical; Evaluation of the sealing capacity of MTA, IV and OZE in apical retrobturation Dones, Valentina; Mohn, Claudia Ester; Gualtieri, Ariel Félix; Pinasco, Laura E,; Sierra, Liliana Gloria; Rodriguez, Pablo A.; Casadoumecq, Ana Clara En el presente trabajo, se evaluó la capacidad de sellado del mineral de trióxido agregado (MTA), ionómero vitreo (IV) y oxido zinc eugenol (OZE) en retrobturaciones apicales. Cien piezas dentales unirradiculares, fueron divididas en 5 grupos (n=20): 1- control positivo, ápice sin sellar; 2-control negativo, ápice impermeabilizado con esmalte de uñas; 3- retrobturado con MTA; 4- retrobturado con OZE; 5- retrobturado con IV. Al finalizar los tratamientos ex vivo, las piezas fueron sometidas a la prueba de penetración de tinte, mediante sumersión en azul de metileno 2% durante 48 hs. A continuación, se realizó un corte transversal a 1 mm del extremo apical y se midió el porcentaje de tinción como medida de la capacidad de sellado de los materiales de obturación empleados. Los resultados fueron analizados con la prueba de Kruskal-Wallis, seguida por comparaciones de a pares. El porcentaje de tinción no difirió significativamente entre los tratamientos con MTA e IV, pero éstos mostraron un porcentaje significativamente menor con respecto al tratamiento con OZE. Además, no se encontraron diferencias significativas entre el tratamiento con OZE y el control positivo. Estos resultados demuestran que el IV y el MTA tienen similar capacidad de sellado en retrobturación in vitro, y que a su vez, constituyen mejores selladores que el OZE, que no demostró ser un sellador efectivo, al menos en las condiciones estudiadas.; In the present work, the sealing capacity of the aggregate trioxide ore (MTA), vitreous ionomer (IV) and zinc oxide eugenol (OZE) in apical retrobturations was evaluated. One hundred unirradicular dental pieces were divided into 5 groups (n = 20): 1- positive control, unsealed apex; 2-negative control, apex waterproofed with nail polish; 3- retrobturado with MTA; 4- retrobturado with OZE; 5- retrobturado with IV. At the end of the ex vivo treatments, the pieces were subjected to the dye penetration test, by submerging in 2% methylene blue for 48 hours. Next, a cross section was made 1 mm from the apical end and the percentage of staining was measured as a measure of the sealing capacity of the sealing materials used. The results were analyzed with the Kruskal-Wallis test, followed by pairwise comparisons. The percentage of staining did not differ significantly between treatments with MTA and IV, but these showed a significantly lower percentage compared to treatment with OZE. In addition, no significant differences were found between the treatment with OZE and the positive control. These results demonstrate that IV and MTA have similar sealing capacity in retrobturation in vitro, and that in turn they constitute better sealants than OZE, which did not prove to be an effective sealant, at least under the conditions studied.

Predicting key educational outcomes in academic trajectories: a machine-learning approach Musso, Mariel Fernanda; Rodríguez Hernández, Carlos Felipe; Cascallar, Eduardo C. Predicting and understanding different key outcomes in a student's academic trajectory such as grade point average, academic retention, and degree completion would allow targeted intervention programs in higher education. Most of the predictive models developed for those key outcomes have been based on traditional methodological approaches. However, these models assume linear relationships between variables and do not always yield accurate predictive classifications. On the other hand, the use of machine-learning approaches such as artificial neural networks has been very effective in the classification of various educational outcomes, overcoming the limitations of traditional methodological approaches. In this study, multilayer perceptron artificial neural network models, with a backpropagation algorithm, were developed to classify levels of grade point average, academic retention, and degree completion outcomes in a sample of 655 students from a private university. Findings showed a high level of accuracy for all the classifications. Among the predictors, learning strategies had the greatest contribution for the prediction of grade point average. Coping strategies were the best predictors for degree completion, and background information had the largest predictive weight for the identification of students who will drop out or not from the university programs.