Conformal field theories from deformations of theories with Wn symmetry Babaro, Juan Pablo; Giribet, Gaston Enrique; Ranjbar, Arash We construct a set of nonrational conformal field theories that consist of deformations of Toda field theory for sl(n). In addition to preserving conformal invariance, the theories may still exhibit a remnant infinite-dimensional affine symmetry. The case n=3 is used to illustrate this phenomenon, together with further deformations that yield enhanced Kac-Moody symmetry algebras. For generic n we compute N-point correlation functions on the Riemann sphere and show that these can be expressed in terms of sl(n) Toda field theory ((N-2)n+2)-point correlation functions.

Computational predictions on the interactions of parabens with a dipalmitoyl phosphatidylcholine lipid bilayer and the human serum albumin protein Masone, Diego Fernando; Félix Rubio Dalmau Parabens are esters of para-hydroxybenzoic acid extensively used as preservatives in cosmetics and pharmaceutics. In the recent years their safe use has been questioned, mainly due to their estrogenic activity, their concentration in breast cancer tissues and their endocrine disrupting consequences on the reproductive system. In this study, the interaction of five forms of paraben ligands (namely methyl, ethyl, propyl, butyl and heptyl) with a model dipalmitoylphosphatidylcholine bilayer and the human serum albumin transport protein, was assessed using extensive atomistic molecular dynamics simulations. Free energy profiles for the insertion of each ligand into the lipid bilayer were computed along an appropriate reaction coordinate. Protein-ligand interactions were evaluated through a combination of an efficient sampling of the protein-ligand hydrogen bond network and the full system side chains, together with an all-atom force field. Simulation results show that among the paraben ligands studied, methyl, propyl and butyl parabens penetrate more easily the bilayer and show higher binding affinity to human serum albumin in terms of their hydrogen bonding network, supporting the experimental hypotheses of their potential risk to human health.

Chromatin architecture: A new dimension in the dynamic control of gene expression Ramirez Prado, Juan Sebatian; Rodriguez Granados, Natalia Yaneth; Ariel, Federico Damian; Raynaud, Cecile; Benhamed, Moussa As the most recent evidence of eukaryotic cell complexity, genome architecturehas astounded the scientific community and prompted a variety of technical andcognitive challenges. Several technologies have emerged and evidenced theintegration of chromatin packaging and topology, epigenetic processes, andtranscription for the pertinent regulation of gene expression. In the presentaddendum we present and discuss some of our recent research, directedtowards the holistic comprehension of the processes by which plants respond toenvironmental and developmental stimuli. We propose that the study of genometopology and genomic interactions is essential for the understanding of themolecular mechanisms behind a phenotype. Even though our knowledge andunderstanding of genome architecture and hierarchy has improved substantiallyin the last few years -in Arabidopsis and other eukaryotes -, there is still a long way ahead in this relatively new field of study. For this, it is necessary to take advantage of the high resolution of the emerging available techniques, and perform integrative approaches with which it will be possible to depict the role of chromatin architecture in the regulation of transcription and ultimately, physiological processes.

Filosofía, política e ideología en América Latina; Philosophy, politics and ideology in Latin America de Gainza, Mariana Cecilia A lo largo de los últimos años, una cantidad de conocidos nombres de la filosofía contemporánea han comparecido en nuestra escena latinoamericana, involucrándose con las urgencias de la interpretación coyuntural. Esas tentativas de lectura de una actualidad involucran tanto los intereses teóricos de la filosofía, como los problemas que enfrenta la práctica emancipatoria y las confrontaciones ideológicas en contextos de fuerte polarización. Aquí analizamos ese tipo de entrecruzamientos, prestando atención a ciertas perspectivas, como la de García Linera o Balibar, que insisten en no abandonar el concepto, al mismo tiempo que se comprometen con determinadas batallas políticas e ideológicas.; In the last years, a number of famous names of contemporary philosophy have reported in our Latin American scene, getting involved with urgencies of interpreting the critical juncture. These attempts reading the actuality involve no just theoretical interests of philosophy, but practical problems of emancipatory politics and ideological confrontations in contexts of high polarization. In this article, we analyze such crossovers, focusing on certain perspectives, such as García Linera or Balibar, that insist on not abandon the conceptual work, while they commit to specific political and ideological struggles.

El gimnasio, el crossfit y el running aportan pistas para pensar un nuevo modo de individuación Rodríguez, Alejandro Damián El campo de los estudios sociales del deporte se ha constituido, en las últimas décadas en nuestro país, en un espacio prolífico para la producción de literatura especializada. La producción socioantropológica del deporte se ha concentrado en estudiar al fenómeno desde dos perspectivas opuestas y fundadas en el terreno: la primera colocando el foco en los espectadores (Alabarces, 2006; Garriga Zucal, 2007; Moreira, 2008), la segunda decididamente concentrada en sus practicantes, ya sean deportistas profesionales o amateurs (Branz, 2016; Hang, 2014, Moreira, 2011). El fútbol, la natación, el boxeo, el rugby, el polo y el automovilismo, entre otras manifestaciones deportivas que podríamos denominar tradicionales, han sido objeto privilegiado de los cientistas sociales que se dedicaron a pensar el fenómeno.Sin embargo, las últimas décadas del siglo XX nos ha alumbrado una novedad que tiene plena vigencia también en la actualidad-: la aparición de un conjunto de técnicas corporales que de manera muy difícil, salvo a costa de volver muy elástica la categoría aglutinadora de deporte, podrían ser clasificadas como tales. Me refiero específicamente a la aparición y/o masificación de: a) el entrenamiento mecánico y rutinario del gimnasio, b) las técnicas corporales que mixturan gimnasia y danza denominadas de fitness grupal, c) el entrenamiento militarizado del crossfit y d) el running, disciplina hermanada al deporte atletismo pero que se ha ampliado para un público que excede notoriamente a los atletas federados en esa competencia o que lo practican de modo recreativo. La aparición y/o la masificación de este conjunto de técnicas corporales plantean un desafío para el campo de los estudios sociales del deporte. ¿Cómo se procesa dentro suyo un conjunto de prácticas que evita la competencia, característica central y excluyente de toda disciplina deportiva, o que, en otros términos, remplaza la competencia individual y/o grupal frente a otras personas o equipos por una donde el elemento central para comprenderla es la competencia que el entrenado en estas técnicas emprende contra sí mismo? La hipótesis que propongo es que para comprender la aparición y/o masificación de este conjunto de prácticas es necesario prestar atención a un nuevo modo de individuación que corre en paralelo. Algunos autores lo han denominado el individuo pragmático.

Shotgun Metagenomic Profiles Have a High Capacity To Discriminate Samples of Activated Sludge According to Wastewater Type Ibarbalz, Federico Matias; Orellana, Esteban; Figuerola, Eva Lucia Margarita; Erijman, Leonardo This study was conducted to investigate whether functions encoded in the metagenome could improve our ability to understand the link between microbial community structure and function in activated sludge. By analyzing data sets from six industrial and six municipal wastewater treatment plants covering different configurations, operational conditions and geographic regions, we found that wastewater influent composition was an overriding factor shaping the metagenomic composition of activated sludge. Community GC-content profiles were conserved within treatment plants on a time scale of years, and between treatment plants sharing similar influent wastewater. Interestingly, GC-content of represented phyla covary with the average GC-content of the corresponding WWTP metagenome. This suggests that the factors influencing nucleotide composition act similarly across taxa, and therefore that the variation in nucleotide content is driven by environmental differences between WWTPs. While taxonomic and functional richness were correlated, shotgun metagenomics complemented taxon-based analyses in the task of classifying microbial communities involved in wastewater treatment systems. The observed taxonomic dissimilarity between full-scale wastewater treatment plants receiving influent with varied composition, as well as the inferred taxonomic and functional assignment of recovered genomes from each metagenome, were consistent with underlying differences in the abundance of distinctive sets of functional categories. These conclusions were robust with respect to plant configuration, operational and environmental conditions and even to differences in laboratory protocols.

First description of the male of the spider Tibellus paraguensis Simon, 1897 (Araneae: Philodromidae), with new distribution records Achitte Schmutzler, Helga Cecilia; Rubio, Gonzalo Daniel The genus Tibellus Simon, 1875 currently includes 51 species (WSC 2016); it presents some taxonomic difficulties, due to morphological variability, and similarities among some congeners (Efimik 1999). Studies on the genus were undertaken by Gertsch (1933) and Schick (1965) from America, Tikader (1980) from India, Van den Berg & Dippenaar-Schoeman (1994) from the Afrotropical region, and Efimik (1999) from the East Palearctic region. From the Neotropical region six species of Tibellus are known, of which five are represented only by females: T. affinis O. Pickard-Cambridge, 1898 (juvenile), T. chilensis Mello Leitão, 1943, T. insularis Gertsch, 1933, T. paraguensis Simon, 1897 and T. spinosus Schiapelli & Gerschman, 1941; and only one, T. duttoni (Hentz, 1847), is known from both sexes (WSC 2016). This demonstrates the incomplete knowledge of a region where new species still can be expected. From Argentina two species are known, T. spinosus and T. paraguensis (CAA 2016). In this paper, the male of T. paraguensis is described for the first time and further illustrations of the female are provided with new geographic records for this species, including the first record from Bolivia.

Electrochemical Oxidation of the Antiretroviral Drug Nelfinavir on Modified Screen-printed Electrodes Asturias Arribas, Laura; Delfino, Mario Raul; Alonso Lomillo, María Asunción; Domínguez Renedo, Olga; Arcos Martínez, Maria Julia This paper describes the voltammetric study of the electrochemical oxidation of the antiretroviral drug Nelfinavir using a screen-printed sensor modified with carbon nanotubes. The performance of the sensor in the determination of the drug was characterized in terms of precision (RSD 5.05 %, n=5) and capability of detection (10.99±0.87 μM for α=β=0.05, n=5) under optimized voltammetric conditions of pH, accumulation time and potential, in the calibration range from 10 to 150 μM of NFV. In order to check the viability of the device, the determination of the analyte in pharmaceutical and biological samples was carried out and its performance was also validated comparing it with HPLC.

The sharp maximal function approach to L p estimates for operators structured on Hörmander’s vector fields Bramanti, Marco; Toschi, Marisa We consider a nonvariational degenerate elliptic operator of the kind Lu ≡ Xq i,j=1 aij (x)XiXju where X1, ..., Xq are a system of left invariant, 1-homogeneous, Hörmander’s vector fields on a Carnot group in R n , the matrix {aij} is symmetric, uniformly positive on a bounded domain Ω ⊂ R n and the coefficients satisfy aij ∈ V MOloc (Ω) ∩ L ∞ (Ω). We give a new proof of the interior W2,p X estimates kXiXjukLp(Ω0) + kXiukLp(Ω0) ≤ c n kLukLp(Ω) + kukLp(Ω)o for i, j = 1, 2, ..., q, u ∈ W2,p X (Ω), Ω 0 b Ω and p ∈ (1, ∞), first proved by Bramanti-Brandolini in [3], extending to this context Krylov’ technique, introduced in [15], consisting in estimating the sharp maximal function of XiXju.

Crecimiento, desorción térmica y daño por bombardeo iónico en films de C60depositados sobre Cu(111); Growth, thermal desorption and ion bombardment damage inC60films deposited on Cu(111) Vidal, Ricardo Alberto; Bonetto, Fernando Jose; Quintero Riascos, Vanessa Alexandra; Bonin, Claudio Julio; Ferron, Julio En el presente trabajo caracterizamos el crecimiento y desorción térmica de C60 sobre Cu(111) por medio de espectroscopia de electrones Auger (AES) y difracción de electrones de baja energía (LEED). Las películas de C60 fueron crecidas sobre el sustrato por sublimación de C60 desde una celda de Knudsen a 350°C, dentro de una cámara de ultra alto vacío (~10-9Torr). También,determinamos las condiciones de medición de espectros de dispersión de iones lentos (LEIS), estimando el daño por irradiación producido por las dosis típicas utilizadas en estos experimentos (~1014 iones/cm2). Para analizar el daño por bombardeo iónico (H+, He+ y Ar+, con energías de incidencia de 2, 4 y 8 keV) de las películas de C60 se siguió la evolución temporal del plasmón característico de los enlaces p de los átomos de Carbono que conforman la molécula de C60, mediante espectroscopia de pérdidade energía de electrones (EELS). Además, se tomaron espectros Auger antes y después del bombardeo para caracterizar y cuantificar el daño producido.El presente estudio muestra que: el crecimiento de C60 sobre Cu(111) es capa tras capa; la desorción de la primera monocapa es diferente a las demás, quedando solo una monocapa cuando es calentado a 500°C; y solo se detectódaño por irradiación, para las dosis relevantes, cuando la muestra fue bombardeada con Ar+; Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED) were used to characterize the growth and thermal desorption of C60 on Cu(111). C60 films were grown by sublimation from a Knudsen cell at 350°C, placed in an ultra-high vacuum chamber (UHV) (~10-9Torr). We estimated the best conditions to obtain low energy ion scattered spectra (LEIS) by measuring the irradiation damage produced by typical doses used in theseexperiments (~1014iones/cm2 ). In order to analyze the potential damage of the sample by ion bombardment (2 , 4 and 8 keV H+ , He+ and Ar+ ), we monitored the evolution of the characteristicplasmon due to π-bonds of the C60 molecule C atoms by Electron Energy Loss Spectroscopy (EELS). In addition, Auger spectra (AES) were taken before and after irradiation to characterize and quantify the damage. Our study shows that: C60 growths on Cu(111) layer by layer; the desorption of the first monolayer is different to the desorption of the other layers, remaining the first monolayer even when the substrate is heated up to 500°C and; damage by ion bombardment, at the used dose, was only detected when the sample was under Ar+ irradiation

P35 and P22 Toxoplasma gondii antigens abbreviate regions to diagnose acquired toxoplasmosis during pregnancy: toward single-sample assays Costa, Juan Gabriel; Peretti, Leandro Ezequiel; Garcia, Valeria Soledad; Peverengo, Luz; Gonzalez, Veronica Doris Guadalupe; Gugliotta, Luis Marcelino; Dalla Fontana, María; Lagier, Claudia Marina; Marcipar, Ivan Sergio Background: P35 and P22 Toxoplasma gondii proteins are recognized by specific IgG at the early infection stage, making them ideal for acute toxoplasmosis pregnancy control. Both proteins have been studied to discriminate between acute and chronic toxoplasmosis. However, results were hardly comparable because different protein obtainment procedures led to different antigens, the referencepanels used were not optimally typified, and avidity tests were either not performed or narrowly examined. Methods: We bioinformatically predicted P35 andP22 regions with the highest density of epitopes, and expressed them in pET32/BL21DE3 alternative expression system, obtaining the soluble proteins rP35a and rP22a. We assessed their diagnostic performance using pregnant woman serum samples typified as: not infected, NI (IgG−, IgM−), typical-chronic, TC (IgM−, IgG+), presumably acute, A (IgG+, IgM+, low-avidity IgG), and recentlychronic, RC (IgG+, IgM+, high-avidity IgG).

Changes in Species Richness and Composition of Tiger Moths (Lepidoptera: Erebidae: Arctiinae) among Three Neotropical Ecoregions Beccacece, Hernán Mario; Zeballos, Sebastián Rodolfo; Zapata, Adriana Inés Paraná, Yungas and Chaco Serrano ecoregions are among the most species-richterrestrial habitats at higher latitude. However, the information for tiger moths, one of the most speciose group of moths, is unknown in these ecoregion. In this study, we assess the species richness and composition on these three ecoregion. Also we investigated whether tiger moths species composition is influenced by climatic factors and altitude. Tiger moths species were obtained with samples from 71 sites using standardized protocols (21 sites were in Yungas, 19 in Paraná and 31 in Chaco Serrano). Rarefaction-extrapolation curves, non-parametric estimators for incidence and sample coverage indices were performed to assess species richness in the ecoregions studied. Non metric multidimensional scaling and adonis test were performed to compare the species composition of tiger moths among ecoregions. Permutest analysis and Pearson correlation were used to evaluate the relationship among species composition and annual mean temperature, annual temperature range, annual precipitation, precipitation seasonality and altitude. Among ecoregions Paraná was the richest with 125 species, followed by Yungas with 63 species and Chaco Serrano with 24 species. Species composition differed among these ecoregions, although Yungas and Chaco Serrano were more similar than Paraná. Species composition was significantly influenced by climatic factors and altitude. This study showed that species richness and species composition of tiger moths differed among the three ecoregions assessed. Furthermore, not only climatic factors and altitude influence the species composition of tiger moths among ecoregions, but also climatic seasonality at higher latitude in Neotropical South America region becomes an important factor.

Bee, hummingbird or mixed pollinated Salvia species mirror pathways to pollination optimization: a morphometric analysis based on the Pareto front concept Strelin, Marina Micaela; Sazatornil, Federico David; Benitez-Vieyra, Santiago Miguel; Ordano, Mariano Andrés Optimization of flower phenotypes to ensure pollination by agents differing in their match with fertile flower structures can involve fitness trade-offs if the aspects of the phenotype that enhance the fitness contribution of one pollinator are detrimental for pollination by the other agents. If these trade-offs are substantial, flower optimization for specialized pollination is expected. However, optimization for generalized pollination may also take place in trade-off scenarios, as long as the joint contribution of two or more types of pollinators to global pollination fitness is greater than each individual contribution. We use an observational approach to evaluate the role of pollination fitness trade-offs in flower trait optimization, a matter seldom addressed because of the difficulties in conducting experiments. A pattern searching tool based on the Pareto front concept, borrowed from the fields of economics and engineering, was used to test for fitness trade-off patterns in the flower shape of four Salvia (Lamiaceae) species. Two are pollinated exclusively either by bees or by hummingbirds; the remaining present mixed pollination systems, with varying contributions of bee and hummingbird pollination. The patterning of flower shape in this study suggests a bee-hummingbird pollination trade-off in Salvia and the optimization of generalized flower shapes.

Terpenes: Natural Products for Controlling Insects of Importance to Human Health?A Structure-Activity Relationship Study Dambolena, José Sebastián; Zunino, María Paula; Herrera, Jimena María; Pizzolitto, Romina Paola; Areco, Vanessa Andrea; Zygadlo, Julio Alberto Many insects affect food production and human health, and in an attempt to control these insects the use of synthetic insecticideshas become widespread. However, this has resulted in the development of resistance in these organisms, human diseases,contamination of food, and pollution of the environment. Plants natural products and essential oil components such as terpenesand phenylpropenes have been shown to have a significant potential for insect control. However, the molecular properties relatedto their insecticidal activity are not well understood. The purpose of this review is to provide an overview of the toxicity ofterpene compounds against three insects of importance to human health: lice, cockroaches, and Triatominae bugs and to evaluatewhich molecular descriptors are important in the bioactivity of terpenes. For the insects studied, quantitative structure-activityrelationship (QSAR) studies were performed in order to predict the insecticidal activity of terpene compounds. The obtainedQSAR models indicated that the activity of these compounds depends on their ability to reach the targets and to interact withthem.The QSAR analysis can be used to predict the bioactivities of other structurally related molecules. Our findings may providean important contribution in the search for new compounds with insecticidal activity.

First record and revised description of Herpetocypris helenae G. W. Müller, 1908 (Crustacea, Ostracoda) from the Neotropics (central-west Argentina) D'ambrosio, Débora Sabina; Diaz, Analia Roxana; García, Adriana Laura; Claps, Maria Cristina The genus Herpetocypris Brady & Norman, 1889 has a wide distribution in most of the zoogeographical regions except in the Neotropical Region, where only three species have so far been found these being H. reptans (Baird, 1835), H. chevreuxi (Sars, 1895) and H. pectinata Brehm, 1934. We here report the first record of Herpetocypris helenae G. W. Müller, 1908 from the Neotropical Region, and provide a complete revised description and illustration of the valves and soft parts of this species, as well as information on ecological factors affecting its distribution and aspects of morphological variability of its valves.

Challenges in the conservation of the work of León Ferrari Baldomá, Gabriela; Maier, Marta Silvia When dealing with contemporary art, conservators have to address not only the material aspects of the artwork but also other highly complex issues. The Argentinian artist Leon Ferrari is a representative example. He created avant-garde art installations but also worked with traditional techniques. His works raise dilemmas over concepts such as authorship, authenticity, legitimacy of art. Some of his artworks only interested him as a means to express his opinions and he was not concerned about alterations in their appearance. Therefore, what should be kept in them is not in an area of certainty for conservators. An essential key for achieving a responsible and respectful conservation result, is to understand the ideology involved in each ‘art piece’ created by Ferrari.

Pollination biology of Echinopsis leucantha (Cactaceae): Passerine birds and exotic bees as effective pollinators Gorostiague, Pablo; Ortega Baes, Francisco Pablo Cactus flowers have traditionally been considered to be specialized to certain pollination guilds, but pollination studies reveal that most species are actually generalists. This suggests that floral traits are not always predictive of the animal visitors that pollinate cactus flowers. Here, we studied the pollination of Echinopsis leucantha (Gillies ex Salm-Dyck) Walp., an endemic cactus of Argentina, whose floral traits would suggest that it is pollinated by moths. The floral lifespan and flower availability throughout the reproductive period were evaluated. Field experiments were carried out to study the reproductive system and the identity and effectiveness of floral visitors. Echinopsis leucantha flowers had a nocturnal anthesis time that extended into the following morning. The species was self-incompatible. Floral visitors included moths, bees, and passerine birds. However, diurnal visitors were more effective as pollinators than nocturnal ones. The flowers of E. leucantha were phenotypically specialized (sphingophily); however, the pollination system was functionally and ecologically generalized. The results confirm that generalized pollination systems are widespread among species of the Echinopsis genus with nocturnal flowers, for which diurnal pollinators seem to have a key role in fruit and seed production. Our study constitutes the first record of passerine bird pollination in the Cactaceae for mainland South America.

Systems-level effects of ectopic galectin-7 reconstitution in cervical cancer and its microenvironment Higareda Almaraz, Juan Carlos; Ruiz Moreno, Juan S.; Klimentova, Jana; Barbieri, Daniela; Salvador Gallego, Raquel; Ly, Regina; Valtierra Gutierrez, Ilse A.; Dinsart, Christiane; Rabinovich, Gabriel Adrián; Stulik, Jiri; Rösl, Frank; Rincon Orozco, Bladimiro ckgroundGalectin-7 (Gal-7) is negatively regulated in cervical cancer, and appears to be a link between the apoptotic response triggered by cancer and the anti-tumoral activity of the immune system. Our understanding of how cervical cancer cells and their molecular networks adapt in response to the expression of Gal-7 remains limited.MethodsMeta-analysis of Gal-7 expression was conducted in three cervical cancer cohort studies and TCGA. In silico prediction and bisulfite sequencing were performed to inquire epigenetic alterations. To study the effect of Gal-7 on cervical cancer, we ectopically re-expressed it in the HeLa and SiHa cervical cancer cell lines, and analyzed their transcriptome and SILAC-based proteome. We also examined the tumor and microenvironment host cell transcriptomes after xenotransplantation into immunocompromised mice. Differences between samples were assessed with the Kruskall-Wallis, Dunn?s Multiple Comparison and T tests. Kaplan?Meier and log-rank tests were used to determine overall survival.ResultsGal-7 was constantly downregulated in our meta-analysis (p < 0.0001). Tumors with combined high Gal-7 and low galectin-1 expression (p = 0.0001) presented significantly better prognoses (p = 0.005). In silico and bisulfite sequencing assays showed de novo methylation in the Gal-7 promoter and first intron. Cells re-expressing Gal-7 showed a high apoptosis ratio (p < 0.05) and their xenografts displayed strong growth retardation (p < 0.001). Multiple gene modules and transcriptional regulators were modulated in response to Gal-7 reconstitution, both in cervical cancer cells and their microenvironments (FDR < 0.05 %). Most of these genes and modules were associated with tissue morphogenesis, metabolism, transport, chemokine activity, and immune response. These functional modules could exert the same effects in vitro and in vivo, even despite different compositions between HeLa and SiHa samples.ConclusionsGal-7 re-expression affects the regulation of molecular networks in cervical cancer that are involved in diverse cancer hallmarks, such as metabolism, growth control, invasion and evasion of apoptosis. The effect of Gal-7 extends to the microenvironment, where networks involved in its configuration and in immune surveillance are particularly affected.

Comportamiento de alimentación del pingüino penacho amarillo del sur Eudyptes chrysocome y del pingüino de Magallanes Spheniscus magellanicus en Isla de los Estados, Tierra del Fuego, Argentina; Foraging behavior of southern rockhopper penguin Eudyptes chrysocome and Magellanic penguin Spheniscus magellanicus at Isla de los Estados, Tierra del Fuego, Argentina Rosciano, Natalia Gimena El comportamiento de alimentación y dieta de las aves marinas, engeneral, varía con la localidad, el sexo y el estadio del ciclo anual. Además, en una misma región pueden alimentarse distintas especies con requerimientos tróficos similares, aunque no podrían co-existir sin diferencias ecológicas (principio de exclusión competitiva). Así, estudiar la segregación inter- e intra-específica es relevante para entender la estructura y funcionamiento de estas comunidades. Dos especies de pingüino anidan en simpatría en Bahía Franklin, Isla de los Estados, el pingüino penacho amarillo del sur Eudyptes chrysocome (PPA) y el pingüino de Magallanes Spheniscus magellanicus (PM). El objetivogeneral de esta tesis fue estudiar las áreas de alimentación, las estrategias de búsqueda de alimento y el uso de la columna de agua y el nivel trófico durante distintas etapas del ciclo anual de dichas especies y sus diferencias inter- e intra-específicas. El estudio serealizó durante tres temporadas reproductivas (2011?2013), utilizando registradores con sensores de posicionamiento satelital, profundidad y temperatura, modelados en un sistema de información geográfico e isótopos estables. Los PM mostraron leves diferencias entre sexos en su comportamiento de buceo y una gran superposición en las áreas del marutilizadas para alimentarse. También se registró variabilidad inter-anual en el comportamiento alimentación y el nivel trófico de la especie, aunque no se reflejó en una menor supervivencia de los pichones. Por su parte, las hembras de PPA mostraron segregación intra-específica en la población, utilizando distintas áreas de alimentación yzonas en la columna de agua, durante la etapa de cuidado temprano de pichones. Durante la etapa de cuidado tardío, los análisis de isótopos estables de PPA mostraron un comportamiento de aprovisionamiento selectivo, siendo los pichones alimentados con presas de mayor calidad energética que las que ingieren sus padres; aunque no se observaron diferencias en las áreas utilizadas por los adultos para auto-aprovisionamiento y aprovisionamiento de los pichones. Los nichos isotópicos de ambas especies mostraron una fuerte segregación inter-específica durante la etapa de cuidado temprano, reduciendo la competencia durante esta etapa, en la que están restringidos a explotar recursos dentro de un área limitada. Las hembras de PPA se alimentaron en un nivel trófico menor y en aguas abiertas en comparación con los PM, que se alimentaron en un nivel trófico mayor y en aguas costeras. Fuera de la temporada reproductiva, durante el viaje de pre-muda, semantuvo la segregación inter-específica en las áreas utilizadas para alimentarse y el nivel trófico, prevaleciendo las diferencias ecológicas observadas dentro la temporada de cría en el comportamiento de alimentación de ambas especies en esta localidad. Este estudio aporta aspectos novedosos sobre el comportamiento y la ecología trófica de las dos especies de pingüinos que viven en simpatría en Isla de los Estados. Además, resulta importante para comprender el funcionamiento del ecosistema marino del Atlántico Sudoccidental a través de sus predadores tope, y para realizar futuras acciones de conservación en el área de estudio, a través de la información sobre las áreas de importancia para los pingüinos en la región.; Foraging behavior and diet of seabirds, in general, varies with locality, sex and the life stage. Also, different species with similar trophic requirements can feed in the same region, though they could not co-exist without ecological differences (principal of competitive exclusion). Studying the inter-and intra-specific segregation is relevantto understand the structure and functioning of this communities. Two penguin species nest in sympatry in Bahia Franklin, Isla delos Estados, southern rockhopper penguins Eudyptes chrysocome(RHP) and Magellanic penguins Spheniscus magellanicus(MP). The general objective of this thesis was to study the foraging areas, search for food strategies, the use of the water column and trophic level during different stages of the annualcycle of the species mentioned and their inter-and intra-specific differences. The study was carried on during three breeding seasons (2011-2013) using devices with GPS, depth and temperature sensor, modelling in geographic information system and stable isotopes. MP showed small differences between sexes in their diving behavior and great overlap in the foraging areas at sea. Even though they showed inter-annual variability in the foraging behavior and the trophic level, it was not reflected in a smaller survival of the chicks. On their behalf, female RHP showed intra-specific segregation in the population, using different foraging areas and zones in the water column, during the early chick rearing period. During the late chick rearing period, stable isotope analysis on RHP showed a selective provisioning behavior, being the chicks fed with higher quality prey type than their parents; though no differences were found in the foraging areas used for adult self-provisioning and chick provisioning. Isotopic niche of both species showed a strong inter-specific segregation during early chick rearing period. Female RHP fed on a lower trophic level and off-shore compared to MP that fed at higher trophic level and in coastal areas. Outside the breeding season, during the pre-molt trip, the inter-specific segregation in the foraging areas and trophic level was maintained, suggestingthat the ecological differences observed in the foraging behaviourduring the breeding season prevailed on this location. This study shows novel aspects of the behavior and trophic ecology of the two species of penguins that live in sympatry on Isla de los Estados. Also, it is important to understand how the South-Atlantic marine ecosystem works though their top predators and for future conservation actions regarding marine protected areas for penguins in the region.

Comportamiento de incubación de Chororó (Taraba Major) Y Choca Co‐ Mún (Thamnophilus Caerulescens) en Argentina; Incubation behavior of Great Antshrike (Taraba major) and Variable Antshrike (Thamnophilus caerulescens) in Argentina Schaaf, Alejandro Alberto; Peralta, Giovana Claudia; Diaz, Agustín Eduardo; Luczywo, Ayelen; Peluc, Susana Ines  La familia Thamnophilidae agrupa unas doscientas especies de aves paseriformes. Si bien en los últimos años se ha avanzado en el conocimiento de la biología reproductiva de muchas de estas especies, todavía hay algunas para las que ciertos parámetros reproductivos son aún desconocidos. Con el presente trabajo contribuimos al conocimiento de la biología reproductiva del Chororó (Taraba major) y la Choca Común (Thamnophilus caerulescens), aportando principalmente datos sobre su comportamiento de incubación en la provincia de Córdoba, Argentina, en el extremo sur de su distribución. Registramos tamaño de la puesta, duración del período de incubación y otras variables asociadas al comportamiento de incubación utilizando sensores remotos y observaciones directas, y medimos cre‐ cimiento de pichones en el nido. En las dos especies los adultos compartieron tareas de incubación, y el porcentaje de atención diario al nido fue elevado en ambas (T. major: 91,46%; T. caerulescens: 92,52%). El patrón de incubación durante las horas de luz resultó diferente entre las especies. Para T. major, con el transcurso del día aumento la duración y disminuyó la cantidad de los eventos de incubación y recesos. En contraposición, para T. caerulescens ambas variables se mantuvieron constantes a lo largo del día. Los datos aportados por este trabajo enriquecen el conocimiento de la biología reproductiva de especies de tamnofílidos poco estudiadas, y sirven de base para investigar respecto a los factores que moldean los comportamientos de cuidado parental en estas aves.  ; The Thamnophilidae family comprises approximately 200 species of passeriforme birds. Even though in the last years there has been advancement in the knowledge of the reproductive biology of many of those species, there are still species for which several reproductive parameters are unknown. With this work we contribute to the knowledge of the reproductive biology of the Great Antshrike (Taraba major) and the Variable Antshrike (Thamnophilus caerulescens) mainly providing data on their incubation behavior in the province of Córdoba, Argentina, corresponding to their southernmost distribution. We recorded clutch size, total duration of the incubation period, and other variables associated with incubation behavior by means of remote sensors and direct observations. In both species, adults shared incubation duties and nest attentiveness was high (T. major: 91.46%; T. caerulescens: 92.52%). The pattern of incubation for daylight hours was different between the species. In the case of T. major, the duration of on and off bouts increased during the course of the day, and the number of bouts decreased. In contrast, for T. caerulescens both variables remained constant throughout the day. The data provided in this study enriches our knowledge of the reproductive biology of understudied Thamnophilidae species, and are useful as baseline information to investigate the factors that shape parental care behaviors in these birds.