Las puntas de proyectil "en mandorla" de Inca Cueva 7: Caracterización tipológica e historia de vida (Puna de Jujuy, Argentina); Mandorla projectile points recovered from the Inca Cueva 7: Typological characterization and history lessons (Puna of Jujuy, Argentina), Aschero, Carlos Alberto; Hocsman, Salomón; Ratto, Norma Rosa Se analizan las puntas de proyectil en "mandorla" recuperadas en un depósito intencional de múltiples artefactos del sitio Inca Cueva 7 (Puna de Jujuy, Argentina), datado ca. 4000 años AP. El análisis se centra en su diseño y en sus alternativas de uso, entendiendo por éstas el modo en que pudieron utilizarse ambos extremos de cada punta. Para mostrar las características de este diseño se incluye la comparación con un conjunto de piezas en "mandorla" del sitio Camarones 14 (costa del norte de Chile) y se realizan diversas pruebas estadísticas. Por último, considerando las características de tres ejemplares recuperados del sitio argentino, se discuten sus ventajas en maximizar el rendimiento de las puntas y de los intermediarios de astil.Palabras clave : puntas de proyectil; puntas en "mandorla"; tipología; cazadores recolectores; Arcaico; Puna de Jujuy.; Mandorla projectile points recovered in a ca. 4000 years BP intentional deposit of artifacts from the Inca Cueva 7 site (Puna of Jujuy, Argentina), are analyzed. They are studied in terms of their design and use alternatives, because it could be used one extreme or the other, turning the points at the foreshaft; besides these artifacts could be the result of resharpening of blades and/or shafted parts. We include a comparison between mandorla projectile points from Inca Cueva 7 site and mandorla artifacts from Camarones 14 site (Northern Chile). Several statistical tests are performed. Then, the benefits to maximize the performance of foreshaft, are discussed on the basis of the characteristics of three specimens recovered from the Argentinian site studied

Tarifas aduaneras e industria azucarera en la Argentina. El discurso azucarero en torno al proteccionismo a fines del siglo XIX Lenis, Maria Lidia El presente artículo examina el rol desempeñado por el Centro Azucarero Argentino en la construcción de un discurso azucarero a fines del siglo XIX. En este sentido, advertimos que la defensa del proteccionismo constituyó uno de los tópicos centrales de la retórica azucarera, en tanto las tarifas aduaneras eran consideradas como condición necesaria para asegurar el desarrollo industrial, entendido como la vía de la independencia económica. Se asoció la implantación fabril con la “civilización” y el “progreso”. De este modo, el establecimiento y consolidación de este tipo de actividades económicas eran presentadas como una labor patriótica que permitía el avance del estado en territorios que aparecían dominados por la “barbarie”. A su vez, en este alegato aparecieron claramente delineadas las funciones que el estado debía adoptar con respecto al sector industrial. De esta manera, se reclamaba que el Estado debía contemplar los intereses del conjunto de país, y no asociar el progreso con los límites de la llanura pampeana. Si bien es cierto que muchas de estas líneas argumentativas se encontraban presentes en la década anterior, las mismas fueron sistematizadas en el discurso de la corporación azucarera y de su publicación mensual, la “Revista Azucarera”. Es así, que a partir de 1894 podemos detectar la presencia de un “discurso azucarero”, sobre todo en materia arancelaria, que con algunos matices se mantendrá inalterable hasta la llegada del radicalismo al poder.

Distribución espacial de la miseria en hogares de Santiago del Estero y procesos territoriales en Argentina, 1991-2001; Spatial distribution of misery at household in Santiago del Estero and territorial processes in Argentina, 1991-2001 Longhi, Hugo Fernando El campesinado santiagueño conforma uno de los núcleos argentinos donde la miseria alcanzó las mayores proporciones a fines del siglo XX. En este trabajo se analizaron los principales procesos territoriales ocurridos durante la década de 1990, asociados al comportamiento de la miseria. Dentro de tales procesos se indagó sobre los cambios en las grandes masas de cultivo, la ganadería, la cantidad y superficie de las explotaciones agropecuarias y la dinámica de la población. Como fuentes de información se utilizaron los Censos Nacionales de Población, Hogares y Viviendas de 1991 y 2001, los Censos Nacionales Agropecuarios de 1988 y 2002 y las estadísticas vitales del periodo intercensal. Los principales resultados se relacionaron con la desarticulación entre el crecimiento de la superficie cultivada con soja y la economía campesina, en un contexto de fuerte deforestación.; Peasantry in Santiago composes one of the Argentinean groups where misery reached the largest proportions by the end of the XX century. In this work we analyzed the main Territorial processes occurred during the 1990’s decade associated to the behavior of misery. In these said processes we enquired on the changes in the large masses of cultivations, livestock rearing, and surface of the agricultural exploitations and the dynamic of the population. As information sources we resorted to the National Censuses of Population, Household and Housing from 1991 to 2001, the Agricultural Censuses for the years 1988 and 2002 and the vital statistics of the inter-censual period. The main results are related to the de-articulation between the growth of the surface cultivated with soybean and peasant economy in a context of heavy deforestation.

Cu(II)-reduction by Escherichia coli cells is dependent on respiratory chain components Volentini, Sabrina Inès; Farias, Ricardo Norberto; Rodríguez Montelongo, Luisa; Rapisarda, Viviana Andrea Copper is both an essential nutrient and a toxic element able to catalyze free radicals formation which damage lipids and proteins. Although the available copper redox species in aerobic environment is Cu(II), proteins that participate in metal homeostasis use Cu(I). With isolated Escherichia coli membranes, we have previously shown that electron flow through the respiratory chain promotes cupric ions reduction by NADH dehydrogenase-2 and quinones. Here, we determined Cu(II)-reductase activity by whole cells using strains deficient in these respiratory chain components. Measurements were done by the appearance of Cu(I) in the supernatants of cells exposed to sub-lethal Cu(II) concentrations. In the absence of quinones, the Cu(II)-reduction rate decreased ~70% in respect to the wild-type strain, while this diminution was about 85% in a strain lacking both NDH-2 and quinones. The decrease was ~10% in the absence of only NDH-2. In addition, we observed that quinone deficient strains failed to grow in media containing either excess or deficiency of copper, as we have described for NDH-2 deficient mutants. Thus, the Cu(II)-reduction by E. coli intact cells is mainly due to quinones and to a lesser extent to NDH-2, in a quinone-independent way. To our knowledge, this is the first in vivo demonstration of the involvement of E. coli respiratory components in the Cu(II)-reductase activity which contributes to the metal homeostasis.

Química computacional: Simulaciones matemáticas del comportamiento de átomos y moléculas Leiva, Ezequiel Pedro M.; Estrin, Dario Ariel La química computacional utiliza los modelos matemáticos de la química teórica y los procesa por computadora para entender la estructura y las propiedades de las sustancias que analiza. Resolviendo las ecuaciones que los forman, esos modelos permiten comprender las interacciones entre átomos y moléculas, así como predecir comportamientos de la materia que resulta difícil estudiar en el laboratorio. El método es potencialmente aplicable a la resolución de cualquier problema químico.

Modelling diffusion and adsorption of As species in Fe/GAC adsorbent beds Sigrist, Mirna Edit; Beldomenico, Horacio Ramon; Tarifa, Enrique Eduardo; Pieck, Carlos Luis; Vera, Carlos Roman Background: Arsenic decontamination of drinking water by adsorption is a simple and robust operation. When designing packed bed adsorbers for arsenic, the main problems are the slow diffusion kinetics of As in microporous media and the lack of simple equations for predicting the performance of the equipment. Commercial iron-doped granular activated carbon adsorbents (Fe/GAC) for groundwater arsenic abatement were studied in this work. Basic parameters for arsenate (AsV) adsorption were measured and their performance at larger scale was simulated with an approximate analytical model. Results: In the 0-300 μgAs L-1 range, the AsV adsorption isotherm on Fe/GAC was found to be approximately linear. Assuming Henry's law for adsorption and homogeneous surface diffusion with constant diffusivity for intrapellet mass transfer, an approximate model for flow and adsorption of arsenate inside packed bed adsorbers was developed, and reduced to an analytic compact solution using the quasi-lognormal distribution (Q-LND) approximation. The use of this model with fitted and reported parameters enabled the approximate simulation of industrial adsorbers and home point-of-use filters. Results show that industrial adsorbers meet the breakthrough condition with incomplete utilization of the adsorbent unless convenient process configurations are used. In point-of-use systems with short residence times intraparticle diffusion would drastically reduce the adsorbent performance. Conclusion: Assuming linear adsorption of AsV over Fe/GAC, an analytical approximate solution for flow and adsorption in packed beds can be obtained. The model seems to represent correctly the main features of industrial and home filters, however, more experimental data is necessary for scale-up purposes.

Fluidez verbal según tipo de tarea, intervalo de tiempo y estrato socioeconómico, en niños escolarizados; Verbal Fluency according to task type, time interval and socioeconomic status in school-aged children Arán Filippetti, Vanessa Este estudio tuvo como objetivo analizar la fluidez verbal (FV) según tipo de tarea (semántica vs. fonológica), intervalo de tiempo (1-15seg. vs. 16-30seg. vs. 31-45seg. vs. 46-60seg.) y estrato socioeconómico (medio vs. bajo) en niños escolarizados. Se trabajó con una muestra de 248 niños de 8 a 12 años de edad de diferentes estratos socioeconómicos (ESE). Se administraron el test de FV semántica (FVS) y fonológica (FVF) y otras pruebas cognitivas para evaluar posibles asociaciones. Los resultados indicaron diferencias significativas según el ESE en el número total de palabras generadas en ambos tipos de FV y en función del tiempo. Los niños de estrato socioeconómico bajo presentaron más dificultades para generar palabras en la FVF y a partir de los 16 segundos en donde se ponen en juego los procesos controlados. Se analizó además la relación entre diferentes variables socioeconómicas y la FV y se encontró que el nivel de instrucción de la madre fue el único predictor significativo. Finalmente, los resultados revelaron que el lenguaje, la inteligencia y otras funciones ejecutivas predicen la FV aunque con diferencias según el tipo de tarea semántica o fonológica. Se discuten los resultados en función de la utilidad de la tarea como medida del procesamiento cognitivo y del impacto que tiene el ESE sobre el procesamiento controlado y el funcionamiento ejecutivo.; The aim of this study was to analyze verbal fluency (VF) according to task type (semantic vs. phonologic), time interval (1-15seg. vs. 16-30seg. vs. 31-45seg. vs. 46-60seg.) and socioeconomic status (medium vs. low) in school-aged children. The sample included 248 children aged between 8 and 12 years from different socioeconomic status (SES). Semantic and phonological VF tests and other cognitive tasks were administered in order to evaluate possible associations. The results indicated significant differences according to SES as regards the total number of words generated in both VF tasks and as a function of time. Children from lower socioeconomic status had demonstrated more difficulty in generating words in the phonological task, and since the 16 seconds where controlled processes are at stake. In addition, the relationship between different socioeconomic variables and VF was analyzed, and it was found that the level of instruction of the mother was the only significant predictor. Finally, the results revealed that language, intelligence and other executive functions predict VF performance, despite differences in terms of semantic or phonologic tasks. The results are discussed considering the usefulness of the task as a measure of cognitive processing and the impact that SES has on controlled processing and executive functioning.

Clasificación geomorfológica automatizada en terrazas del Noreste del Macizo Norpatagónico, Argentina; Automated classification of landforms on terraces of northeast Patagonian Massif, Argentina Genchi, Sibila Andrea; Carbone, Maria Elizabeth; Piccolo, Maria Cintia; Perillo, Gerardo Miguel E. Se realizó una clasificación automatizada de las geoformas en terrazas del noreste del Macizo Norpatagónico, Argentina. La clasificación se realizó mediante parametrización del relieve a partir del modelo digital de elevación del proyecto Shuttle Radar Topography Mission (NASA), a través del empleo de un Sistema de Información Geográfica. En este estudio se derivaron modelos digitales como el índice de posición topográfica (TPI) y pendiente, que se emplearon como base para la clasificación. Se realizaron sucesivos ajustes en la definición del TPI y de las reglas de clasificación de geoformas, apoyados en la supervisión de la cartografía, fotografías aéreas, imágenes satelitales y observaciones en el terreno. De acuerdo con la clasificación propuesta en este estudio, el área está dominada por las geoformas pendiente abierta y planicie, que alcanzan el 45 y 33% del área total, respectivamente. Las restantes clases geomorfológicas cubren superficies menores: lomas, cerros y sierras (8%); bajos, valles en V (7,5%); valles en U (3%) y pendiente alta (2,6%).; We made an automated classification of landforms on terraces of northeast Patagonian Massif, Argentina. Classification of landforms was carried out using parameterization of the relief from the Shuttle Radar Topography Mission digital elevation model within a geographical information system. Digital models such as topographic position index (TPI) and slope derived from elevation data were employed as a basis for classification. Successive adjustments were made for TPI and classification rules, which were supervised base on aerial photographs, satellite imagery and survey of land. According to the classification proposed in the present study, the area is dominated by open slope and plain landforms, reaching 45 and 33% of the total area, respectively. The remaining classes occupy smaller areas: ridges, hills and mountains (8%), low, valleys in the form of V (7.5%); valleys in the form of U (3%) and high slope (2.6%).

Flooding effects on phosphorus dynamics in an Amazonian mangrove forest, Northern Brazil Mendoza, Ursula N.; Cruz, Cleise Cordeiro da; Menezes, Moirah; Lara, Ruben Jose Aims and methods We examined porewater salinity, soil redox potential (Eh), soil extractable phosphate (extr.-P), leaf phosphorus (leaf-P) and plant growth in relation to inundation frequency (IF) and mangrove species distributions along a 600 m transect in the Bragança Peninsula, North Brazil. Results The forest species composition changed across the tidal zone with Avicennia germinans dominating (99.1%) the high intertidal (HI) zone where the IF was 41–67 d.y−1 , Rhizophora mangle, Laguncularia racemosa and A. germinans co-occured in the mid intertidal (MI), and a mixed R. mangle (47.1%) - A, germinans (41.2%) stand occupied the low intertidal (LI) zone with an IF of 124–162 d.y−1 . Low IF resulted in high Eh levels (200 mV) in the HI zone relative to the LI where Eh ranged from 0–100 mV. The IF showed a significant positive correlation with extr.-P (r=0,89; p=0.05) and a negative association with Eh (r=−0,75; p=0.05). Conclusion An ANCOVA confirmed that Eh and extr.P were influenced by flooding. Variations in these factors were reflected in patterns of P leaf tissue concentrations across the gradient; however, a MANCOVA showed that leaf-P was not related to tree height, tree volume or basal area. Waterlogging conditions, porewater salinity, and P dynamics in the sediment appear to influence the forest structure. We suggest that P availability plays an important role in controling mangrove species distributions but not their growth.

Prolonged exposure to growth hormone impairs insulin signaling in the heart. Miquet, Johanna Gabriela; Giani, Jorge Fernando; Martinez, Carolina Soledad; Muñoz, Marina Cecilia; Gonzalez, Lorena; Sotelo, Ana Isabel; Boparai, Ravneet K.; Masternak, Michal M.; Bartke, Andrzej; Dominici, Fernando Pablo; Turyn, Daniel Acromegaly is associated with cardiac hypertrophy, which is believed to be a direct consequence of chronically elevated GH and IGF1. Given that insulin is important for cardiac growth and function, and considering that GH excess induces hyperinsulinemia, insulin resistance, and cardiac alterations, it is of interest to study insulin sensitivity in this tissue under chronic conditions of elevated GH. Transgenic mice overexpressing GH present cardiomegaly and perivascular and interstitial fibrosis in the heart. Mice received an insulin injection, the heart was removed after 2 min, and immunoblotting assays of tissue extracts were performed to evaluate the activation and abundance of insulin-signaling mediators. Insulin-induced tyrosine phosphorylation of the insulin receptor (IR) was conserved in transgenic mice, but the phosphorylation of IR substrate 1 (IRS1), its association with the regulatory subunit of the phosphatidylinositol 3-kinase (PI3K), and the phosphorylation of AKT were decreased. In addition, total content of the glucose transporter GLUT4 was reduced in transgenic mice. Insulin failed to induce the phosphorylation of the mammalian target of rapamycin (mTOR). However, transgenic mice displayed increased basal activation of the IR/IRS1/PI3K/AKT/mTOR and p38 signaling pathways along with higher serine phosphorylation of IRS1, which is recognized as an inhibitory modification. We conclude that GH-overexpressing mice exhibit basal activation of insulin signaling but decreased sensitivity to acute insulin stimulation at several signaling steps downstream of the IR in the heart. These alterations may be associated with the cardiac pathology observed in these animals.

Game approach to distributed model predictive control Giovanini, Leonardo Luis This study introduces a framework for distributed model predictive control (MPC) based on dynamic games, where centralised and decentralised control algorithms can be viewed as dynamical games with coupled control sets. The original optimisation problem is decomposed into smaller coupled optimisation problems in a distributed structure, which is solved iteratively. Then, the resulting dynamic game is analysed using the theory of potential games to derive the properties of the resulting algorithms. This sheds new light on the properties of existing MPC algorithms and allows us to establish a unified framework to analyse them. The control problem of a heat-exchanger network (HEN) is used to illustrate the effectiveness, practicality and limitations of the proposed framework.

Profetas a salto de mata Nespolo, Maria Jimena La voz es el punto en donde lo animal, lo humano y la cultura se cruzan. A partir de la voz, se exhibe y se efectúa el carácter ritual de la letra. Aquí se analizan distintos textos de la escena religiosa latinoamericana de fin de milenio, en el intento de discernir el horizonte simbólico e ideológico de las voces que la pueblan.

Aplicaciones no coronarias de la tomografía computada cardíaca; Non-Coronary Applications of Cardiac Computed Tomography Rodriguez Granillo, Gaston Alfredo; Ingino, Carlos; Cherro, Alejandro; Lambre, Hector; Lylyk, Pedro El gran valor predictivo negativo de la angiografía coronaria por tomografía computada multidetector (ACTCMD), ha llevado a la creciente incorporación del método en el algoritmo diagnóstico para pacientes con sospecha de enfermedad coronaria. Además, gracias a una adquisición volumétrica del área cardíaca y al gatillado electrocardiográfico, la ACTCMD permite simultáneamente, realizar reconstrucciones submilimétricas en todos los ángulos posibles y en distintos tiempos del ciclo cardíaco. Esto genera un escenario propicio para la evaluación morfológica y funcional, y abre un amplio abanico de aplicaciones no coronarias posibles; la mayoría de ellas evaluables durante el mismo estudio de las arterias coronarias, y sin requerimiento de contraste ni radiación adicional. La capacidad de evaluar simultáneamente morfología y función, permite una aproximación comprensiva de un amplio espectro de patologías mediante un mismo estudio.; Multi-detector row computed tomography coronary angiography (MDCT-CA) has been incorporated in the diagnostic algorithm of patients with suspected coronary artery disease due to its significant negative predictive value. In addiction, volume acquisition and ECG-cardiac gating allow submillimeter reconstructions in all possible angles at different time positions within the cardiac cycle. This produces a favorable scenario for the morphological and functional evaluation, and opens the possibility of using this technique in other territories; most of them can be evaluated during the study of the coronary arteries without requiring additional contrast agents or radiation. The capability of the method for the simultaneous evaluation or morphology and function allows a comprehensive approach of wide scope of conditions within the same study.

Antioxidant response of tobacco (Nicotiana tabacum) hairy roots after phenol treatment Sosa Alderete, Lucas Gastón; Agostini, Elizabeth; Medina, Maria Inés Phenol is released to the environment from a wide variety of industrial effluents and it causes severe problems to human health and ecosystem. In the present study, we determined that Nicotiana tabacum hairy roots (HRs) double transgenic (DT) for two peroxidase genes (tpx1 and tpx2) showed higher phenol removal efficiency than wild type (WT) HRs after 120 h of phenol treatment at the expense of endogenous H 2O 2. Besides, to determine whether phenol could induce oxidative stress on tobacco HRs, we analyzed the antioxidant response, superoxide anion (O 2 -) localization and malondialdehyde (MDA) levels. Both HRs treated with phenol, showed significant increases in peroxidase (PX) activity mainly at the end of the assay (120 h) being PX activity from transgenic HRs 40% higher than that of WT HRs. Superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities showed significant increases from 24 to 120 h of phenol treatment. PX, SOD and APX isoforms were also analyzed and slight changes were observed only in PX patterns. Both HRs showed significant differences in total glutathione (TGSH) content during treatment, being higher in DT HRs than in WT HRs. At the end of the assay, a greater accumulation of O 2 - in different root zones was observed in WT and DT HRs. Moreover, phenol was able to increase the MDA levels in WT HRs from 48 to 120 h of the treatment, but no significant changes were observed in DT HRs. Results suggest that under these experimental conditions, DT HRs would be more tolerant to phenol than WT HRs.

Vibrational spectra of Tris(maltolato)gallium(III): A new interesting antitumoral agent Wagner, Claudia Cecilia; Parajón Costa, Beatriz Susana; Baran, Enrique José The FTIR and FT-Raman spectra of the gallium(III) complex of 3-hydroxy-2-methyl-4-pyrone (maltol), tris(maltolato)gallium(III), a new very promising antitumoral drug, were recorded and briefly discussed by comparison with the spectra of uncoordinated maltol and with some related species.

The space-bandwidth product in the joint transform correlator optical encryption setup Cuadrado Laborde, Christian Ariel; Lancis, Jesús In this work we study the joint transform correlator (JTC) optical encryption setup through the Wigner function. We found analytical expressions for the spatial and spatial frequency extent of the encrypted signal. Since the JTC is inherently an asymmetrical optical system, different expressions were found for each spatial axis and for their associated spatial frequency axes. We also compare these results with the dual random phase encoding technique. Finally, we found an analytical expression for the minimum separation between channels that avoids crosstalk in a wavelength multiplexing JTC architecture.

Mise au point d'outils de prévision de l'évolution de la stabilité de la structure de sols sous l'effet de la gestion organique des sols; Developping tools to predict soil aggregate stability as influenced by soil organic matter management; Desarrollo de herramientas de previsión de la evolución de la estabilidad estructural de los suelos bajo efecto de la gestión orgánica de los suelos Chenu, Claire; Abiven, Samuel; Annabi, Mohamed; Barray, S.; Bertrand, M.; Bureau, F.; Cosentino, Diego; Darboux, F.; Duval, O.; Fourrié, L.; Francou, C.; Houot, S.; Jolivet, C.; Laval, K.; Le Bissonnais, Y.; Lemée, L.; Menasseri, S.; Pétraud, J. P.; Verbèque, B. La estabilidad estructural está una propiedad física importante de los suelos, indicadora de su sensibilidad al sellado superficial del suelo y a la erosión. Los suelos limosos, que cubren superficies importantes en Francia y en el norte de Europa tienen debido a su textura y a su bajo contenido en materias orgánicas, una baja estabilidad estructural. En un contexto donde hay preocupación de la disminución de contenido en materia orgánica y donde se diversifica prácticas y sistemas de cultivo, aparece necesario desarrollar herramientas de predicción de la estabilidad estructural en función de la cuantidad y de la calidad de materias orgánicas. Desarrollamos una función de pedotransferencia (o relación estadística) que liga estabilidad de la estructura a su constitución, en particular el contenido en carbono orgánico, a partir de una base de datos Agresta de 480 suelos reunidos durante el proyecto. El examen de 7 ensayos de larga duración o de redes de parcelas sobre suelos limosos mostró mejoramientos de la estabilidad de la estructura en algunos años con prácticas que permiten un aumento del contenido en C en el horizonte de superficie (no laboreo, praderas temporarias, scv, aportes repetidos de compostas). El contenido en C total del horizonte está así un mejor indicador de la estabilidad estructural que las fracciones orgánicas (azucares solubles al agua caliente, materias orgánicas en partículas) o que la biomasa de los microorganismos. Experimentaciones de aporte de materias orgánicas (residuos de cultivos, compostas…) en suelos al laboratorio permitieron confirmar que le papel de estos aportes estuvo esencialmente indirecto, por la estimulación de los microorganismos del suelo que su descomposición lleva; estos microorganismos que agregan las partículas de los suelos por sus secreciones o mecánicamente. Propusimos un modelo predictivo de la estabilidad estructural seguido a aportes orgánicos cuyos se conoce la calidad bioquímica: Cantis-Stab, que copla un modelo de descomposición de materias orgánicas con una función estadística. Como la gestión de las materias orgánicas constituye un volante de acción mayor para actuar sobre la sensibilidad de los suelos limosos al sellado superficial y a la erosión, las herramientas propuestas pueden servir de base a preocupaciones agronómicas o al aporte razonado de productos residuales orgánicos al suelo.; La stabilité structurale est une propriété physique des sols importante, indicatrice de leur sensibilité à la battance et à l’érosion. Les sols limoneux, qui couvrent des surfaces importantes en France et dans le Nord de l’Europe ont, du fait de leur texture et de leur faible teneur en matières organiques, une stabilité structurale faible. Dans un contexte où l’on se préoccupe de la diminution de la teneur en matière organique des sols, où se développe l’apport de produits résiduaires organiques au sol et où se diversifient les pratiques culturales et les systèmes de culture, il apparaît nécessaire de développer des outils de prédiction de la stabilité structurale en fonction de la quantité et de la qualité des matières organiques. Nous avons développé une relation statistique qui relie la stabilité de la structure à la constitution des sols, en particulier à leur teneur en carbone organique (C), à partir d’une base de données AGRESTA de 480 sols assemblée pendant cette étude. Cependant sa faible capacité prédictive ne permet pas de l’utiliser comme fonction de pédotransfert. L’examen de 7 essais de longue durée ou réseaux de parcelles sur sols limoneux a montré des améliorations de la stabilité de la structure en quelques années avec des pratiques qui permettent une augmentation de la teneur en C dans l’horizon de surface (non labour, prairies temporaires, semis direct sous couvert végétal (SCV), apports répétés de composts). La teneur en C totale de l’horizon est souvent un meilleur prédicteur de la stabilité structurale que des fractions organiques (carbohydrates solubles à l’eau chaude, matières organiques particulaires) ou que la biomasse des microorganismes. Des expérimentations réalisées en laboratoire d’apport de matières organiques (résidus de culture, composts) à des sols limoneux, nous ont permis de confirmer que le rôle de ces apports était essentiellement indirect, par la stimulation des microorganismes du sol que leur décomposition entraîne. Les microorganismes agrégent les particules de sols par leur sécrétions ou mécaniquement. Nous avons proposé un modèle prédictif de la stabilité structurale suite à des apports organiques dont on connaît la qualité biochimique : CANTIS-STAB, qui couple un modèle de décomposition des matières organiques à une fonction statistique. Comme la gestion des matières organiques constitue un volant d’action majeur pour agir sur la sensibilité de sols limoneux à la battance et à l’érosion, les outils proposés doivent être développés, afin de servir de base à des préconisations agronomiques ou à l’apport raisonné de produits résiduaires organiques au sol.; Aggregate stability is a major soil physical property, which is a good indicator of the sensitivity of soils to crusting and erosion. Silty soils, which cover large surface areas in France and Northern Europe, have a low aggregate stability, because of their texture and of their frequent low organic matter contents. In the present context of (i) soil organic matter content depletion, (ii) development of organic wastes application to soils and (iii) diversification of cropping systems, it is necessary to have tools to predict changes in soil aggregate stability with changes in soil organic matter content and quality. Using a data base of 480 soils, established during this study, we developed a statistical relationship which relates soil aggregate stability with soil characteristics, in particular with its organic carbon (C) content. However, its low predictive capacity does not allow to use it as a pedotransfer function. Based on 7 in situ long term experiments or cultivated plots series, we found rapid increased of soil aggregate stability when practices that increases the soil C content in the surface layer are implemented (no till, rotations with leys, permanent coverage of soil with plants, repeated compost additions). The total C content of soil was often better correlated to aggregate stability than other organic variables, such as hot water soluble polysaccharides, particulate organic matter contents, or microbial biomass C. Laboratory experiments, in which a wide range of organic materials (crop residues, composts) were added to soil showed that the effect of the organic materials was indirect, through the stimulation of the microbial decomposers, which aggregated the soil. We proposed a new model to simulate the temporal changes in aggregate stability after organic matter additions of given biochemical qualities and in controlled amounts. “CANTIS-STAB” couples a decomposition model with a statistical function. Managing organic matter in soils is a powerful option to decrease the sensitivity of silty cultivated soils to crusting and erosion. The different tools proposed in this program will be developed further, to serve as a basis to optimize agronomic practices and organic wastes addition in this perspective.

Antibodies anti-Shiga toxin 2 B subunit from chicken egg yolk: Isolation, purification and neutralization efficacy Parma, Yanil Renee; Chacana, Pablo Anibal; Rogé, Ariel Diego; Kahl, Alan Jonatan; Cangelosi, A.; Geohgegan, P.; Lucchesi, Paula Maria Alejandra; Fernandez Miyakawa, Mariano Enrique Shiga toxins (Stx1 and Stx2) are the main virulence factors of enterohemorrhagic Escherichia coli (EHEC), a foodborne pathogen associated with diarrhea, hemorrhagic colitis and hemolytic uremic syndrome. The aim of this study was to evaluate the antibodies against Stx2 obtained from egg yolks of laying hens immunized with a recombinant Stx2B subunit. A high specific response in serum was observed 25 days after the first immunization and IgY antibodies were extracted from day 47th and purified from egg yolk. A concentration of 0.84 mg of total IgY/ml of egg yolk was obtained, of which 8% were antigen specific. The ability of anti-Stx2B IgY to recognize Stx2B and Stx2 either in solid-phase or in solution were evaluated and compared with anti-Stx2B rabbit antibodies by Western blotting and ELISA. The protective efficacy of IgY against Stx2 was determined by in vitro and in vivo experiments. The results show that IgY was able to recognize Stx2B and Stx2 in denatured conditions, attached to a solid-phase and free in solution. The anti-Stx2B IgY could effectively block the biological activity of Stx2 on Vero cells and protect mice from Stx2 challenge. The data suggest that immunization of hens with Stx2B could be a strategy to obtain at low cost a relatively high concentration of anti-Stx2 egg yolk IgY, able to neutralize Stx2 lethal activity. IgY technology could be an useful tool for research, diagnosis and therapy of EHEC infection.

Fredi Guthmann: el extranjero entre nosotros Venturini, Santiago El poeta franco argentino Fredi Guthmann –Alfredo Jonás Guthmann (San Isidro, 1911- Mar del Plata, 1995)– continúa siendo, una década después de su aparición en la escena literaria, una figura excéntrica, excentricidad que puede leerse tanto en relación con el canon como con el relato mítico que la delinea. Este trabajo llevará a cabo una doble lectura: de la poética de Guthmann y de la inclusión de esa poética en el sistema literario argentino, a través de “refracciones” críticas y de la operación inclusiva por excelencia: la traducción.

Factors that modify early and late reproductive phases in oilseed rape (Brassica napus L.): Its impact on seed yield and oil content Gomez, Nora Valentina; Miralles, Daniel Julio Oilseed rape yield potential could be improved lengthening the duration of the late reproductive phase by increasing the number of grains per unit area. Photoperiod sensitivity could be used as a tool to manipulate the reproductive phase and thereby the number of grains. The aim of this study was to assess (i) the effects of different combinations of photoperiod on the duration of different phases and (ii) analyze how the changes in that duration affect yield (and its components) as well as oil seed content in oilseed rape. Field experiments were conducted in a factorial combination of three cultivars and three photoperiod regimes: natural photoperiod (NP) which represents the control and extended photoperiod of 6h over NP (NP+6) during emergence (E)-flower buds visible (FBV) and FBV-maturity (M) arranged in a randomized complete block design with three replicates, during two years representing three environments. Results showed that oilseed rape evidenced photoperiod responses during vegetative and early reproductive phases. Due to the lack of correlation between the duration of the vegetative and reproductive phases, it is possible to speculate the vegetative period may be altered independently of the modification of the rest of the phases. The positive relationship between grain number per m2 and the duration of the late reproductive phase suggests that yield could be increased by lengthening the duration of that phase. Thus, regardless of the effect on the previous phase, the photoperiod sensitivity found in the early reproductive phase opens the possibility to manipulate the relative durations of vegetative and reproductive phases. Therefore, the length of the reproductive phase will be increased at the expense of a reduction in the duration of the vegetative phase, but without changing the whole duration of the crop cycle. This strategy could increase yield in oilseed rape in the future. Variations in yield were mostly explained by changes in the grain number per unit area without significant correlation with grain weight. However, a negative relationship between grain weight and grain number was found, showing a slight counterbalance in yield, by decreasing the grain weight. Since oil concentration appeared to be a more conservative attribute, increases in crop yield through a higher grain number per unit area would be a suitable strategy for improving oil yield as no reductions in oil concentration can be expected.