PRÁCTICA ESTÉTICA, VANGUARDISMO Y HEGEMONÍA EN RICARDO PIGLIA

The aesthetic reflection corresponding to the production critic- theory of Ricardo Piglia, is part of the debates within the field of Marxist discussion, from the '60s to the present, in Argentina. Piglia's contribution to the discussions about the link between literature and production conditions, aesthetic practice and capitalism ranges from his original reading of Walter Benjamin, Mao Tse-tung, Yuri Tinianov and Russian Formalism, to cultural studies and the Althusserian structuralism. From this complex plot of readings, and in permanent tension with the various currents of the left-wing intelligentsia(s) of his time, Piglia develops some reading hypotheses that he would continue to re-elaborate until his last interventions and conferences. In this sense, I will develop some links between the categories of  aesthetic practice, hegemony and avant-garde, that emerge from piglian aesthetic reflection, in relation to the conditions of the Argentine cultural field of the last century.La reflexión estética correspondiente a la producción crítico-teórica de Ricardo Piglia, se inscribe en los debates al interior del campo de discusión marxista, desde los años ’60 hasta la actualidad, en la Argentina. El aporte de Piglia a las discusiones en torno al vínculo entre literatura y condiciones de producción, práctica estética y capitalismo, va de su original lectura de Walter Benjamín, Mao Tse-tung, Yuri Tinianov y el Formalismo Ruso, a los estudios culturales y el Estructuralismo Althusseriano. A partir de esta compleja trama de lecturas, y en tensión permanente con las diversas corrientes de la intelectualidad de izquierda(s) de su época, Piglia desarrolla algunas hipótesis de lectura que continuaría re-elaborando hasta sus últimas intervenciones y conferencias. Desarrollaré en este sentido, algunos vínculos entre las categorías de práctica estética, hegemonía y vanguardia, que se desprenden de la reflexión estética pigliana, en relación a las condiciones del campo cultural argentino del siglo pasado

Chemical abundance patterns in the inner Galaxy: the Scutum Red Supergiant Clusters

The location of the Scutum Red-Supergiant (RSG) clusters at the end of the Galactic Bar makes them an excellent probe of the Galaxy's secular evolution; while the clusters themselves are ideal testbeds in which to study the predictions of stellar evolutionary theory. To this end, we present a study of the RSGs' surface abundances using a combination of high-resolution H-band spectroscopy and spectral synthesis analysis. We provide abundance measurements for elements C, O, Si, Mg, Ti, and Fe. We find that the surface abundances of the stars studied are consistent with CNO burning and deep, rotationally enhanced mixing. The average a/Fe ratios of the clusters are solar, consistent with a thin-disk population. However, we find significantly sub-solar Fe/H ratios for each cluster, a result which strongly contradicts a simple extrapolation of the Galactic metallicity gradient to lower Galacto-centric distances. We suggest that a simple one-dimensional parameterization of the Galaxy's abundance patterns is insufficient at low Galactocentric distances, as large azimuthal variations may be present. Indeed, we show that the abundances of O, Si and Mg are consistent with independent measurements of objects in similar locations in the Galaxy. In combining our results with other data in the literature, we present evidence for large-scale (~kpc) azimuthal variations in abundances at Galacto-centric distances of 3-5kpc. While we cannot rule-out that this observed behaviour is due to systematic offsets between different measurement techniques, we do find evidence for similar behaviour in a study of the barred-spiral galaxy NGC4736 which uses homogeneous methodology. We suggest that these azimuthal abundance variations could result from the intense but patchy star formation driven by the potential of the central bar.Comment: 13 pages, 9 figures, accepted to Ap

Global Macroevolution and Macroecology of Passerine Song

Studying the macroevolution of the songs of Passeriformes (perching birds) has proved challenging. The complexity of the task stems not just from the macroevolutionary and macroecological challenge of modeling so many species, but also from the difficulty in collecting and quantifying birdsong itself. Using machine learning techniques, we extracted songs from a large citizen science dataset, and then analyzed the evolution, and biotic and abiotic predictors of variation in birdsong across 578 passerine species. Contrary to expectations, we found few links between life‐history traits (monogamy and sexual dimorphism) and the evolution of song pitch (peak frequency) or song complexity (standard deviation of frequency). However, we found significant support for morphological constraints on birdsong, as reflected in a negative correlation between bird size and song pitch. We also found that broad‐scale biogeographical and climate factors such as net primary productivity, temperature, and regional species richness were significantly associated with both the evolution and present‐day distribution of bird song features. Our analysis integrates comparative and spatial modeling with newly developed data cleaning and curation tools, and suggests that evolutionary history, morphology, and present‐day ecological processes shape the distribution of song diversity in these charismatic and important birds

Enigmatic traces in infaunal bivalves from the late Quaternary of Argentina, Southwestern Atlantic. Bioerosion, bioclaustration or nothing?

Ichnological investigations were carried out on late Quaternary shells of the intertidal deep infaunal bivalve Tagelus plebeius (Lightfoot, 1786) found along the southwestern Atlantic, between Uruguay and the southernmost Buenos Aires Province in Argentina. Analyses reveal distinctive marks that are spread on the outer shell surface only. The marks are regular-unbranched-elongate, perpendicular to the outer shell growth lines, with deflections on the margins, never interconnected, without bifurcations, conforming bottom-up constructions. They occur in hundreds of specimens from many samples taken from sediments ranging in age from the late Pleistocene to the Recent. These marks have never been reported or described for this species and their origin and formation remain elusive. We describe these traces thoroughly and we propose an explanation for their preservation on about half the shells examined. Potential destructive boring structures (excavated from outside-in) or bioerosion activities by other macro- or micro-organisms are dismissed. These antimarginal asymmetric traces point instead to a process of constructive bioclaustrations (grown from the bottom-up) produced in situ during the life of the bivalve by unknown symbiont organisms. Additionally, the regular pattern observed for the marks exclude host growth as a consequence of abiotic/extrinsic causes. From a palaeoecological perspective, these structures suggest a biotic interaction that was hitherto undescribed neither for bivalves nor for the late Quaternary of the southwestern Atlantic.Facultad de Ciencias Naturales y MuseoCentro de Investigaciones Geológica

Enigmatic traces in infaunal bivalves from the late Quaternary of Argentina, Southwestern Atlantic. Bioerosion, bioclaustration or nothing?

Ichnological investigations were carried out on late Quaternary shells of the intertidal deep infaunal bivalve Tagelus plebeius (Lightfoot, 1786) found along the southwestern Atlantic, between Uruguay and the southernmost Buenos Aires Province in Argentina. Analyses reveal distinctive marks that are spread on the outer shell surface only. The marks are regular-unbranched-elongate, perpendicular to the outer shell growth lines, with deflections on the margins, never interconnected, without bifurcations, conforming bottom-up constructions. They occur in hundreds of specimens from many samples taken from sediments ranging in age from the late Pleistocene to the Recent. These marks have never been reported or described for this species and their origin and formation remain elusive. We describe these traces thoroughly and we propose an explanation for their preservation on about half the shells examined. Potential destructive boring structures (excavated from outside-in) or bioerosion activities by other macro- or micro-organisms are dismissed. These antimarginal asymmetric traces point instead to a process of constructive bioclaustrations (grown from the bottom-up) produced in situ during the life of the bivalve by unknown symbiont organisms. Additionally, the regular pattern observed for the marks exclude host growth as a consequence of abiotic/extrinsic causes. From a palaeoecological perspective, these structures suggest a biotic interaction that was hitherto undescribed neither for bivalves nor for the late Quaternary of the southwestern Atlantic.Fil: Richiano, Sebastián Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Aguirre, Marina Laura. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Farinati, Ester Amanda. Universidad Nacional del Sur. Departamento de Geología; ArgentinaFil: Davies, Karen Elizabeth. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Castellanos, Ignacio. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Gómez-Peral, Lucia. E.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentin

Glucose-coated gold nanoparticles transfer across human brain endothelium and enter astrocytes in vitro

The blood-brain barrier prevents the entry of many therapeutic agents into the brain. Various nanocarriers have been developed to help agents to cross this barrier, but they all have limitations, with regard to tissue-selectivity and their ability to cross the endothelium. This study investigated the potential for 4 nm coated gold nanoparticles to act as selective carriers across human brain endothelium and subsequently to enter astrocytes. The transfer rate of glucose-coated gold nanoparticles across primary human brain endothelium was at least three times faster than across non-brain endothelia. Movement of these nanoparticles occurred across the apical and basal plasma membranes via the cytosol with relatively little vesicular or paracellular migration; antibiotics that interfere with vesicular transport did not block migration. The transfer rate was also dependent on the surface coating of the nanoparticle and incubation temperature. Using a novel 3-dimensional co-culture system, which includes primary human astrocytes and a brain endothelial cell line hCMEC/D3, we demonstrated that the glucose-coated nanoparticles traverse the endothelium, move through the extracellular matrix and localize in astrocytes. The movement of the nanoparticles through the matrix was >10 µm/hour and they appeared in the nuclei of the astrocytes in considerable numbers. These nanoparticles have the correct properties for efficient and selective carriers of therapeutic agents across the blood-brain barrier

Chemokine transport across human vascular endothelial cells

Leukocyte migration across vascular endothelium is mediated by chemokines that are either synthesized by the endothelium or transferred across the endothelium from the tissue. The mechanism of transfer of two chemokines, CXCL10 (interferon gamma inducible protein [IP]-10) and CCL2 (macrophage chemotactic protein [MCP]-1), was compared across dermal and lung microvessel endothelium and saphenous vein endothelium. The rate of transfer depended on both the type of endothelium and the chemokine. The permeability coefficient (Pe) for CCL2 movement across saphenous vein was twice the value for dermal endothelium and four times that for lung endothelium. In contrast, the Pe value for CXCL10 was lower for saphenous vein endothelium than the other endothelia. The differences in transfer rate between endothelia was not related to variation in paracellular permeability using a paracellular tracer, inulin, and immunoelectron microscopy showed that CXCL10 was transferred from the basal membrane in a vesicular compartment, before distribution to the apical membrane. Although all three endothelia expressed high levels of the receptor for CXCL10 (CXCR3), the transfer was not readily saturable and did not appear to be receptor dependent. After 30 min, the chemokine started to be reinternalized from the apical membrane in clathrin-coated vesicles. The data suggest a model for chemokine transcytosis, with a separate pathway for clearance of the apical surface

The SAMI Galaxy Survey: Global stellar populations on the size-mass plane

We present an analysis of the global stellar populations of galaxies in the SAMI Galaxy Survey. Our sample consists of 1319 galaxies spanning four orders of magnitude in stellar mass and includes all morphologies and environments. We derive luminosity-weighted, single stellar population equivalent stellar ages, metallicities and alpha enhancements from spectra integrated within one effective radius apertures. Variations in galaxy size explain the majority of the scatter in the age--mass and metallicity--mass relations. Stellar populations vary systematically in the plane of galaxy size and stellar mass, such that galaxies with high stellar surface mass density are older, more metal-rich and alpha-enhanced than less dense galaxies. Galaxies with high surface mass densities have a very narrow range of metallicities, however, at fixed mass, the spread in metallicity increases substantially with increasing galaxy size (decreasing density). We identify residual correlations with morphology and environment. At fixed mass and size, galaxies with late-type morphologies, small bulges and low Sersic n are younger than early-type, high n, high bulge-to-total galaxies. Age and metallicity both show small residual correlations with environment; at fixed mass and size, galaxies in denser environments or more massive halos are older and somewhat more metal rich than those in less dense environments. We connect these trends to evolutionary tracks within the size--mass plane.Comment: 25 pages, 18 figures, MNRAS in press Corrected typo in author lis

On breaking the age-metallicity degeneracy in early-type galaxies: infall versus star formation efficiency

The correlation between [Mg/Fe] and galaxy mass found in elliptical galaxies sets a strong constraint on the duration of star formation. Furthermore, the colour-magnitude relation restricts the range of ages and metallicities of the stellar populations. We combine these two constraints with a model of star formation and chemical enrichment including infall and outflow of gas to find that the trend towards supersolar [Mg/Fe] in massive ellipticals excludes a pure metallicity sequence as an explanation of the colour-magnitude relation. An age spread is required, attributable either to a range of star formation efficiencies or to a range of infall timescales. We find that the inferred range of stellar ages is compatible with the small scatter and the redshift evolution of the colour-magnitude relation. Two alternative scenarios can explain the data: fixed infall with an efficiency which is linearly dependent on mass, or a fixed efficiency with a mass-dependent infall timescale t~1/sqrt(M). We conclude that the actual scenario may well involve a combination of these two parameters, with mass dependencies which should span the range of those given above.Comment: 5 pages, 5 figures, uses mn2e.cls. Submitted to MNRA

Do coastal fronts influence bioerosion patterns along Patagonia? Late Quaternary ichnological tools from Golfo San Jorge

Late Quaternary marine molluscan skeletal concentrations from Argentina constitute a remarkable record of variations in palaeoceanographical conditions during interglacial times (mainly ca. 125 ka to present). Particularly, the Golfo San Jorge coastal area represents an extraordinary geographical zone to target from different points of view, mainly due to its linkage between northern and southern Patagonia, characterized by particular and contrasting physico-chemical conditions with direct consequences for littoral marine communities, determining their composition and structure. Among varied biological activities controlled by different environmental factors (i.e., substrate nature, sedimentation rates, water depth, sea surface temperature, salinity, nutrients-productivity), bioerosion traces can provide palaeoenvironmental evidence with important implications for palaeoclimate interpretations. In addition, the application of bioerosion patterns regionally and through time is a recent valuable worthy palaeoenvironmental tool not as yet developed for Patagonia. We attempted to characterize, qualitatively/semiquantitatively, the ichnotaxonomic composition of the coastal area of northern Golfo San Jorge since the Late Pleistocene; to compare results with those obtained for other geographical areas along Patagonia and the Bonaerensian coastal sectors; lastly, to evaluate its palaeoenvironmental/palaeoclimatic significance in a clue area in terms of circulation patterns near the Southern Ocean climatic pump. At Bustamante (Northern Patagonia Frontal System) Domichnia traces were dominant during the Late Pleistocene while Praedichnia in the mid-Holocene. Bustamante exhibits the highest ichnodiversity for the whole Argentinean coastal area. Ichnodiversity is not strongly different between Late Pleistocene and mid-Holocene interglacials and compared to present; however, the relative abundance of some ichnotaxa (e.g., Oichnus, Iramena, Pennatichnus, at Camarones; Oichnus, Iramena, Pinaceocladichnus, at Bustamante) differs across time. These variations, particularly the highest abundance in the Late Pleistocene (mainly Last Interglacial) of traces made by bryozoans- associated at present with modern enhanced productivity levels and coastal fronts in the Argentine continental shelf- point to higher productivity and more intensified northern Patagonia Front, as a result of a different palaeocirculation pattern, reinforcing previous independent sources of evidence based on molluscan palaeobiogeographical analyses.Facultad de Ciencias Naturales y Muse