New ages and chemical analysis on Lower Jurassic volcanism close to the dorsal de Huincul, Neuquén; Nuevas edades del volcanismo Jurásico Inferior de la cuenca Neuquina en la dorsal de Huincul Schiuma, Mario; Llambias, Eduardo Jorge New single zircon ages from hydrocarbon well cores in the A-1 Norte de la Dorsal and Anticlinal Campamento area of the Neuquén basin indicate that 199.0 ± 1.5 Ma andesite lava flow and 203.75 ± 0.26 Ma dacite breccia overlie a 286.5 ± 2.3 Ma granodiorite and 284.0 ± 1.3 Ma andesite dike. The Lower Jurassic volcanics were deposited on a regional erosion surface affecting the Permian rocks. In the studied area there is no record of Middle to Upper Triassic volcanics as in other areas of the basin. Exotic zircon crystals gave ages of Mesoproterozoic, Middle Cambian, Early Devonian and Early Carboniferous, suggesting a poliphasic basement. Chemical analyses of three selected samples show a calc-alkaline signature, supporting the existence of a volcanic arc at the Early Jurassic as it has been proposed for the center of the basin.; Se dan nuevas edades U/Pb en cristales únicos de circón de muestras de corona de pozos exploratorios en el área petrolera A-1 Norte de la Dorsal y Anticlinal Campamento de la cuenca Neuquina. Estas edades permiten acotar un volcanismo Jurásico Inferior apoyado directamente sobre un basamento ígneo del Pérmico Inferior. Una muestra de andesita arrojó una edad de 199,0 ± 1,5 Ma y una de dacita 203,75 ± 0,26 Ma. El basamento está constituido por una granodiorita de 286,5 ± 2,3 Ma intruida por diques de andesita con 284,0 ± 1,3 Ma, ambas rocas están cortadas por una superficie de erosión de carácter regional labrada durante el Triásico, posiblemente Medio. En las perforaciones estudiadas no se han encontrado rocas triásicas. Los circones exóticos hallados indican la existencia de un complejo basamento con edades del Mesoproterozoico, Cámbrico Medio, Devónico Temprano y Carbonífero Temprano. Los análisis químicos muestras una filiación calco-alcalina que apoya la hipótesis de la existencia de un arco volcánico Jurásico Temprano en el centro de la cuenca Neuquina

Nitrosation of N-methylhydroxylamine by nitroprusside: a kinetic and mechanistic study Gutierrez, Maria Marta; Alluisetti, Graciela Beatriz; Olabe Iparraguirre, Jose Antonio; Amorebieta, Valentín Tomás The kinetics of the reaction between aqueous solutions of Na 2[Fe(CN)5NO]•2H2O (sodium pentacyanonitrosylferrate(ii), nitroprusside, SNP) and MeN(H)OH (N-methylhydroxylamine, MeHA) has been studied by means of UV-vis spectroscopy, using complementary solution techniques: FTIR/ATR, EPR, mass spectrometry and isotopic labeling (15NO), in the pH range 7.1-9.3, I = 1 M (NaCl). The main products were N-methyl-N-nitrosohydroxylamine (MeN(NO)OH) and [Fe(CN)5H2O]3-, characterized as the [Fe(CN)5(pyCONH2)]3- complex (pyCONH 2 = isonicotinamide). No reaction occurred with Me2NOH (N,N-dimethylhydroxylamine, Me2HA) as nucleophile. The rate law was: R = kexp [Fe(CN)5NO2-] × [MeN(H)OH] × [OH-], with kexp = 1.6 ± 0.2 × 105 M-2 s-1, at 25.0 °C, and ΔH # = 34 ± 3 kJ mol-1, ΔS# = -32 ± 11 J K-1 mol-1, at pH 8.0. The proposed mechanism involves the formation of a precursor associative complex between SNP and MeHA, followed by an OH--assisted reversible formation of a deprotonated adduct, [Fe(CN)5(N(O)NMeOH)]3-, and rapid dissociation of MeN(NO)OH. In excess SNP, the precursor complex reacts through a competitive one-electron-transfer path, forming the [Fe(CN)5NO]3- ion with slow production of small quantities of N2O. The stoichiometry and mechanism of the main adduct-formation path are similar to those previously reported for hydroxylamine (HA) and related nucleophiles. The nitrosated product, MeN(NO)OH, decomposes thermally at physiological temperatures, slowly yielding NO.

The coordination chemistry of nitrosyl in cyanoferrates: an exhibit of bioinorganic relevant reactions Olabe Iparraguirre, Jose Antonio Sodium nitroprusside (SNP, Na 2 [Fe(CN) 5 (NO)] •2H 2 O) is a widely used NO-donor hypotensive agent, containing the formally described nitrosonium (NO + ) ligand, which may be redox-interconverted to the corresponding one-electron (NO) and two-electron (NO - /HNO) reduced bound species. Thus, the chemistry of the three nitrosyl ligands may be explored with adequate, biologically relevant substrates. The nitrosonium complex, [Fe(CN) 5 (NO)] 2- , is formed through a reductive nitrosylation reaction of [Fe III (CN) 5 (H 2 O)] 2- with NO, or, alternatively, through the coordination of NO 2 - to [Fe II (CN) 5 (H 2 O)] 3- and further proton-assisted dehydration. It is extremely inert toward NO + -dissociation, and behaves as an electrophile toward different bases: OH - , amines, thiolates, etc. Also, SNP releases NO upon UV-vis photo-activation, with formation of [Fe III (CN) 5 (H 2 O)] 2- . The more electron rich [Fe(CN) 5 (NO)] 3- may be prepared from [Fe II (CN) 5 (H 2 O)] 3- and NO, and is also highly inert toward the dissociation of NO (k = 1.6 × 10 -5 s -1 , 25.0 °C, pH 10.2). It reacts with O 2 leading to SNP, with the intermediacy of a peroxynitrite adduct. The [Fe(CN) 5 (NO)] 3- ion is labile toward the release of trans-cyanide, forming the [Fe(CN) 4 (NO)] 2- ion. Both complexes exist in a pH-dependent equilibrium, and decompose thermally in the hours time scale, releasing cyanides and NO. The latter may further bind to [Fe(CN) 4 (NO)] 2- with formation of a singlet dinitrosyl species, [Fe(CN) 4 (NO) 2 ] 2- , which in turn is unstable toward disproportionation into SNP and N 2 O, and toward the parallel formation of a tetrahedral paramagnetic dinitrosyl compound, [Fe(CN) 2 (NO) 2 ]. Emerging studies with the putative nitroxyl complex, [Fe(CN) 5 (HNO)] 3- , should allow for a complete picture of the three nitrosyl ligands in the same pentacyano fragment. The present Perspective, based on an adequate characterization of structural and spectroscopic properties, will focus on the kinetic and mechanistic description of the above mentioned reactions, which display a versatile scenario, fundamentally related to the biologically relevant processes associated with NO reactivity.

La escritura de la historia en Ecuador tiene cuerpo de mujer: A propósito de Baldomera de Alfredo Pareja Diezcanseco Nofal, Silvia Rossana El lenguaje despojado del realismo le sirve al autor, un sobreviviente al igual que su personaje, para pensar una representación de los hechos cuando los gusanos hayan destruído la materialidad de los cuerpos y sus testimonios." En Baldomera, los referentes locales adquieren universalidad en las cuestiones de género: la historia de esta heroína fracasada puede ser leída como la del país, inscrita en el cuerpo de una mujer pobre, fea y negra, que termina sus días en una cárcel. Aunque es fuerte y resiste (sobrevive sin armas la matanza de noviembre de 1922), en los enfrentamientos con la ley -con la violencia racional de sus armas-, ella pierde, esto agrega un elemento más a las tensiones entre la pequeñez y lo grande, presentes en toda la novela. Un poco como el mismo autor, sobreviviente del Grupo de Guayaquil, cuando testifica sobre el trabajo literario de los Cinco como un Puño, intelectuales modernos con voz crítica ante las realidades sociales y las contradicciones de los años treinta.; The language stripped from realism serves the author, a survivor just like his character, to think of a representation of the facts when the worms have destroyed the substance of bodies and testimony." In Baldomera, local references gain universality in regards to genre: the story of this failed heroine can be seen as that of the nation, written into the body of a poor woman, black and ugly, who finishes out her last days in jail. Though she is strong and fights (she survives the November 1922 massacre without being armed), in her encounters with the law-with the rational violence of her weapons-, she loses, this adds another element to the tensions between the small and the large, that are present throughout the novel. A bit like the author himself, survivor of the Guayaquil Group, who testifies for the literary work of the los Cinco como un Puño (Five Like a Fist), modern intellectuals with a critical voice when 1acing the contradictions and social reality 01 the 1930's.

Tensile Properties, Barrier Properties, and Biodegradation in Soil of Compression—Molded Gelatin-Dialdehyde Starch Films Martucci, Josefa Fabiana; Ruseckaite, Roxana Alejandra Glycerol (Gly)‐plasticized gelatin (Ge) films crosslinked with dialdehyde starch (DAS) as environmentally friendly crosslinking agent were successfully produced by compression molding, demonstrating the capacity of gelatin of being transformed into films by using thermoplastic processes. The effect of DAS content on the color, light transmission, total soluble matter (TSM), water uptake (WU), water vapor permeability (WVP), oxygen permeability (OP) as well as biodegradability during soil burial was investigated. The addition of up to 10 wt % DAS (Ge‐10DAS) generated transparent films, with reduced TMS, WU, WVP, and OP values but higher extensivity than the uncrosslinked counterpart. Further incorporating DAS into plasticized‐gelatin matrix conducted to phase separation with detrimental effect of transparency and tensile properties. DAS‐containing films degraded at slow rate than the uncrosslinked counterpart, suggesting that biotic attack during soil burial is restricted by covalent crosslinking points induced by DAS. Ge‐10DAS films lost about 28% of their initial mass within the first 8 days of exposure to degrading medium; therefore, the material can be classified as rapidly degradable.

Kinetic and stability studies of Ru/La2O3 used in the dry reforming of methane Carrara, Carlos Roberto; Múnera Agudelo, John Fernando; Lombardo, Eduardo Agustin; Cornaglia, Laura Maria The catalytic activity toward hydrogen production through the dry reforming of methane was determined for Ru supported on lanthanum oxide. The catalyst remained stable for more than 80 h in the 823-903 K temperature range and reactant partial pressure ratio (PCO2/PCH 4) equal to unity. However, a significant deactivation was observed during the kinetic measurements when the catalyst was exposed to P CO2/PCH4 > 1 at 823 K. In order to establish why the catalyst deactivated, the Ru reactivity in reductive and CO2 rich atmospheres was studied by in situ LRS and XPS spectroscopies. The partial re-oxidation of metallic Ru could be one of the factors that produce the catalyst deactivation. To perform the kinetic measurements, the temperature range and the partial pressure ratios were selected within the window where the Ru catalyst was stable. The kinetic data and supporting spectroscopic evidence is consistent with a mechanism in which the metal and the oxide play key roles in decomposing the paraffin and activating the CO2, respectively.

Study of a multitubular fixed-bed reactor for ethylene production via ethane oxidative dehydrogenation Lopez, Eduardo; Heracleous, Eleni; Lemonidou, Angeliki A.; Borio, Daniel Oscar In the present contribution, a theoretical study of a multitubular fixed bed reactor for the ethane to ethylene oxidative dehydrogenation reaction over a highly active and selective Ni-Nb-O mixed oxide catalyst is presented. Two reactor designs are proposed and their performance is analyzed by means of a mathematical model of the catalytic bed. The results suggest that the reactor operation would be feasible, provided that high heat transfer area per unit volume and low oxygen concentrations along the tube are maintained. A two-bed multitubular reactor with intermediate air injection proved to be superior to a single-bed design. In fact, the two-bed configuration offers higher ethylene production rates, due to the increased ethylene selectivity while operation under lower oxygen partial pressures. © 2008 Elsevier B.V. All rights reserved.

Rigorous formulation for electromagnetic planewave scattering from a generalüshaped groove in a perfectly conducting plane: Comment Skigin, Diana Carina; Depine, Ricardo Angel We show that the problem of scattering of an obliquely incident plane wave by a generalüshaped groove engraved on a perfectly conducting plane, which was recently studied by Basha et al. [J. Opt. Soc. Am. A 24, 1647 (2007)], was solved 11 years ago using the same formulation. This method was further extended to deal with a finite number of grooves and also with complex apertures including several nonlossy and lossy dielectrics, as well as real metals. © 2008 Optical Society of America.

Caffeoyl esters of threonic acid and its lactone from Viguiera Pazensis Uriburu Monasterio, Maria Laura; Gil, Roberto L.; Sosa, Virginia Estela; de la Fuente, Juana Rosa Dos ésteres de derivados de azúcares con ácido cafeico: 3-O-cafeoil-2-C-metil-D-treono-1,4-lactona, ácido 4-O-cafeoil-2-C-metil-D-treónico, junto con los compuestos previamente conocidos: 2-C-metil-D-treono-1,4-lactona, ácido cafeico, carabrona, 5,7,3'-trihidroxi-4'-metoxiflavona y 5,7,3'-trihidroxi-6,4'-dimetoxiflavona fueron aislados de la parte aérea de Viguiera pazensis. Las estructuras fueron determinadas utilizando una combinación de métodos espectroscópicos, incluyendo espectroscopia de RMN en una y dos dimensiones.; Two caffeoyl esters of sugar derivatives: 3-O-caffeoyl-2-C-methyl-D-threono-1,4-lactone, 4-O-caffeoyl-2-C-methyl-D-threonic acid, along with the previously known compounds: 2-C-methyl-D-threono-1,4-lactone, caffeic acid, carabrone, 5,7,3'-trihydroxy-4'-methoxyflavone, and 5,7,3'-trihydroxy-6,4'-dimethoxyflavone were isolated from the aerial parts of Viguiera pazensis. Their structures were elucidated by application of various spectroscopic methods, including 1D and 2D NMR spectroscopy.

Un futuro frente al río. Gestos de interpretación en el discurso de lo urbano Millán, María del Rosario En este trabajo analizo un proyecto de planificación urbana aprobado por el Concejo Deliberante de la Ciudad de Posadas, Misiones, Argentina. Concentro mi atención en relevar ciertos efectos de sentido y gestos de interpretación derivados de este texto en particular. Considero que este tipo de documentos puede ser analizado en tanto materialización del "discurso de lo urbano" entendido como el discurso referido a la organización urbana, que tiene un alcance performativo sobre la figuración física y simbólica de la ciudad, ya que constituye uno de los principales discursos que sustentan y legitiman los actuales procesos de transformación urbana que experimenta la ciudad.; In this paper I analyze a city-planning project approved by the local council of Posadas Misiones, Argentina. My interest is focus on certain effects of sense and gestures of interpretation derived from that particular text. I consider that this type of documents are materializations of what is called “urban discourse”, understood as the speech about urban organization, which has performative effects on the physical and symbolic figuration of the city, because it constitutes one of the main discourses that sustain and legitimize the present processes of urban transformation that experiences the city.

The advertisement call of Argenteohyla siemersi pederseni (Amphibia, Anura, Hylidae) and comments on its taxonomic status Zaracho, Victor Hugo; Areta, Juan Ignacio Argenteohyla siemersi, nominate A. s. siemersi and A. s. pederseni, are currently recognized. It was suggested that analysis of nuptial calls and chromosome structure would contribute to clarify their taxonomic status. In this paper we describe the advertisement call of Argenteohyla siemersi pederseni from Reserva Natural Provincial Iberá, Corrientes, Argentina, and comment on its taxonomic status. The advertisement call of A. s. pederseni is quite variable in duration and number of notes. Additionally it seems to perform synchronized duets. The call of A. s. pederseni is similar to that of A. s. siemersi in note structure and duration, but the fundamental frequency and the number of notes for call were higher in A. s. pederseni than in A. s. siemersi. These data suggest that siemersi and pederseni could belong to different biological species, although further work is needed to support this assertion; Actualmente se reconocen dos subespecies de Argenteohyla siemersi, la nominal A. s. siemersi y A. s. pederseni. Se ha sugerido que estudios cromosómicos y bioacusticos podrfan ayudar a clarificar su estado taxon6mico. En este trabajo describimos por primera vez el canto de advertencia de Argenteohyla sieniersi pederseni sobre la base de una poblaci6n procedente de la Reserva Natural Provincial Ibera, cerca de la localidad de Colonia Carlos Pellegrini, Corrientes, Argentina. El canto de A. s. pederseni es muy variable en duraci6n y numero de notas. Ademas, parecen vocalizar en duos sincronizados evitando la superposici6n de notas. En comparaci6n con la subespecie nominal, existen diferencias con respecto a la frecuencia fundainental y al número de notas por canto, siendo mayor en A. s. pederseni queen A. s. siemersi. Estos datos sugieren que siemersi y pederseni podrfan corresponder a dos especies biol6gicas distintas, pero más trabajo es necesario para corroborar esta propuesta

Facetas de la vulnerabilidad sociodemográfica de la provincia de Misiones (Argentina).; Aspects of the sociodemographic vulnerability of the Province of Misiones (Argentina) Foschiatti, Ana Maria Hilda Geográicamente, el objetivo de este trabajo es describir e interpretar el comportamiento de la distribución de la población y su inluencia en la vulne-rabilidad y en la pobreza de los hogares y de los habitantes de una provincia argentina de frontera. Se consideran las Necesidades Básicas Insatisfechas, el hacinamiento, los problemas del hábitat y las viviendas, los servicios públi-cos y algunas repercusiones en la educación y la protección sanitaria; From the geographical point of view, the purpose of this paper is to de-scribe and interpret the population distribution behaviour, and its inluence on the vulnerability and the poverty in home life and upon the inhabitants of an Argentine frontier province. The Unsatisied Basic Needs, overcrowded hous-ing, habitat and dwelling problems, public services and some of their effects on education and health care are taken into account

First genotoxicity study of Paraná River water from Argentina using cells from the clam Corbicula fluminea (veneroida corbiculidae) and Chinese hamster (Cricetulus griseus Rodentia, Cricetidae) K1 cells in the comet assay Caffetti, Jacqueline Diana; Mantovani, Mário S.; Pastori, María Cristina; Fernocchio, Alberto S. High concentrations of xenobiotics from urban and industrial wastes have contributed to the contamination of many aquatic environments. We used the comet assay to evaluate the genotoxic potential of water collected from the River Paraná, which receives a great deal of waste, at three points (Puerto Piray, Eldorado and Montecarlo) in the Misiones Province of Argentina. The in vivo comet assay used 40 freshwater clams (Corbicula fluminea) while the in vitro comet assay used Chinese hamster (Cricetulus griseus) K1 cell (CHO-K1) cultures with the mutagen ethyl methanesulfonate (EMS) as the positive control and phosphate buffered saline (PBS) as the negative control. Both assays showed statistically significant differences between the three sampling sites in relation to the negative control, the results of this preliminary study indicating that at these three sites water from the Paraná River presents genotoxic potential. Copyright © 2008, Sociedade Brasileira de Genética.

Singlet oxygen quenching by anthocyanin's flavylium cations Rosso, Veridiana V. De; Moran Vieyra, Faustino Eduardo; Mercadante, Adriana Z.; Borsarelli, Claudio Darío The quenching of singlet molecular oxygen (1O2) by the flavylium cation form of six widespread anthocyanin derivatives: cyanidin 3-glucoside (CG), cyanidin 3-rutinoside (CR), cyanidin 3-galactoside (CGL), malvidin (M), malvidin 3-glucoside (MG) and malvidin 3,5-diglucoside (MDG) was studied in 1% HCl methanol solution by time-resolved phosphorescence detection (TRPD) of 1O2 and photostationary actinometry using perinaphthenone and methylene blue as sensitizers, respectively. The average value of the total (k0) and chemical (kc) quenching rate constants were ∼ 4×108 M-1 S-1 and 3×106 M-1 S-1, respectively, indicating the good performance of the studied anthocyanins as catalytic quenchers of 1O2. The quenching efficiency was larger for malvidin than for cyanidin derivatives, probably by the extra electron-donating methoxy group in ring B of the malvidin derivatives; and it was also dependent on the number and type of glycosylated substitution. As observed for other phenolic-like derivatives, the quenching of 1O2 by anthocyanins was mediated by a charge-transfer mechanism, which was modulated by the total number of -OR substituents that increases the electron-donating ability of these compounds.

De obligaciones y derechos en coro y altar. La obra de Juan Gil Trullench Martinez, Ana Maria; Consigli, Julieta M. La creación de diócesis fue uno de los modos que tuvo la monarquía y el pasado para organizar jurisdiccionalmente en Indias. La constitución de los cabildos catedralicios, con sus dignidades, prebendados, raciones y canonjías, además de los oficios, permitieron que funcionara el Coro y el Altar como lo requería del Oficio Divino y la celebración de las misas. Tanto el cumplimiento de las obligaciones que ellos asumían como los derechos que tales cargos conllevaban, como por ejemplo los emolumentos que percibían por estar y participar del Coro y el Altar , fueron materia de normas canónicas y reales y produjeron una abundante doctrina. La proliferación de obras que abordaron ese tema, como de otras que los llevaban inserto en algún capítulo, llevó al teólogo valenciano Juan Gil Trullench a escribir un opúsculo que contuviera todas aquellas cosas que era necesario que supieran para no alegar ignorancia al respecto. A esta intención responde De obligatione assistendi, et canendi in Choro, publicado en Valencia en 1633, obra en la que recogió lo que habían sostenido en distintas ocasiones "reconocidos doctores", sumado a su propio parecer.El trabajo que se presenta contiene la contextualización del tema, el autor y la obra e incluye la traducción del Prefacio, como una primera etapa del procesamiento completo de la obra.

El comercio de la provincia de Corrientes durante la primera mitad del siglo XIX. Un panorama de su evolución Schaller, Enrique Cesar El presente trabajo pretende contribuir al mejor conocimiento de los circuitos mercantiles en la Argentina durante la etapa previa a la organización nacional. Con ese fin se analiza la evolución general del comercio exterior de Corrientes durante la primera mitad del siglo XIX. En ese lapso la economía de esa provincia experimentó grandes fluctuaciones. Tras el considerable crecimiento productivo y comercial durante el siglo XVIII una fuerte crisis afectó al sector ganadero durante la etapa revolucionaria. El nuevo equilibrio logrado en la década de 1820 pareció abrir nuevas posibilidades, sin embargo, en el desenvolvimiento de la economía rioplatense Corrientes se vio relegada a un papel cada vez más marginal sobre todo a partir del largo conflicto contra Rosas en la década de 1840.. Este estudio se basa en la documentación de fiscal de la provincia. En primer lugar se ha tratado de establecer el valor monetario (en pesos plata) de las exportaciones e importaciones. A partir de los montos establecidos se busca reconstruir la evolución general de este tráfico, examinar la importancia de las vinculaciones comerciales de la provincia y la composición de su flujo exportador.; This paper aims to contribute to the better knowledge of commercial circuits in Argentina before the National Organization. It analyzes the evolution of Corrientes’ overall foreign trade during the first half of the nineteenth century. During that time, the economy of the province experienced large fluctuations. Following the considerable growth of production and trade in the eighteenth century, a strong crisis affected the livestock sector during the revolutionary period. The new stability achieved in the 1820 decade seemed to open new possibilities; however, in the economic growth of the Río de la Plata region, Corrientes was relegated to an increasing marginal role, particularly since the extended conflict against Rosas in the decade of 1840. The study is based on fiscal documentation. First, it has tried to establish the monetary value (in pesos silver) of exports and imports, and then, to rebuild the overall evolution of this exchange traffic, considering the importance of the province external commercial linkages and the composition of its export flow.

Guías del Chaco y de Formosa. Útiles informaciones del pasado, valiosas fuentes para investigaciones actuales Beck, Hugo Humberto En la primera mitad del siglo XX se editaron en Formosa y en Chaco diversas Guías con información destinada a productores, a comerciantes, a profesionales y a todo público. Sus datos fueron de suma utilidad para los habitantes de una región con escaso acceso a medios de difusión masiva. Actualmente constituyen una fuente de enorme valor para la reconstrucción del pasado de las actuales provincias del Chaco y de Formosa. El trabajo describe la información reunida en esas publicaciones, las ordena temáticamente y pondera su valor.

Expression of epithelial cadherin in the human male reproductive tract and gametes and evidence of its participation in fertilization Marin Briggiler, Clara Isabel; Veiga, Maria Florencia; Matos, María Laura; González Echeverría, M. F.; Furlong, L. I.; Vazquez, Monica Hebe Epithelial cadherin (E-cadherin) has been involved in several calcium-dependent cell-cell adhesion events; however, its participation in gamete interaction has not been fully investigated. Our results have demonstrated expression of E-cadherin mRNA in the human male reproductive tract showing higher levels in the caput, corpus and cauda epididymis than in the testis. The mature 122 kDa E-cadherin was detected in epididymal protein extracts and was localized in the epithelial cells from the three epididymal regions. Moreover, the 86 kDa E-cadherin ectodomain was found in cauda epididymal and seminal plasma. Western immunoblotting of human sperm protein extracts allowed the identification of four E-cadherin forms (122, 105, 97 and 86 kDa). The protein was localized in the acrosomal region of intact spermatozoa, remained associated with the head of acrosome-reacted cells and was also detected on the oocyte surface. A similar localization was determined for other proteins of the adhesion complex (beta-catenin and actin). Spermatozoa incubated with anti-E-cadherin antibodies showed impaired binding to homologous zona pellucida (ZP); in addition, presence of these antibodies inhibited the penetration of human spermatozoa to ZP-free hamster oocytes. The results presented here describe the expression of E-cadherin in the male reproductive tract and gametes and strongly suggest its involvement in adhesion events during human fertilization. The identification of proteins involved in gamete interaction will contribute to the understanding of the molecular basis of fertilization and help in the diagnosis and treatment of infertility.

Adquisición de significados verbales nuevos por un proceso de asociación multimodal Fernández Feijóo, María Eugenia; Vernis, Sergio; Zanutto, Bonifacio Silvano; Wainselboim, Alejandro Javier Mientras que la adquisición del lenguaje durante la infancia se produce por exposición al contexto lingüístico, en adultos esta capacidad no parecería estar presente, pues la adquisición de las reglas gramaticales de una lengua requiere de procesos de aprendizaje explícitos (concientes). Se ha visto que infantes de 4 a 8 meses pueden asociar información visual con información auditiva de tipo lingüística con breves tiempos de presentación. La mayor dificultad en adultos por adquirir una segunda lengua por simple exposición al contexto lingüístico podría quizás en parte deberse a una dificultad en asociar entradas sensoriales múltiples con el estímulo lingüístico adecuado. Se estudió entonces qué capacidades poseen los adultos de asociar significados a formas verbales nuevas por co-ocurrencia entre acciones y formas lexicales nuevas. Se presentaron como entrenamiento 60 escenas visuales diferentes junto con frases formadas por no palabras que describían las escenas mostradas. Durante el testeo se presentaron 40 escenas nuevas junto con frases nuevas. En el 50% de los casos la frase describía correctamente la escena mostrada (frase Correcta), mientras que en el restante 50% el “verbo” no coincidía con la acción mostrada (frase Incorrecta). Los participantes decidían lo más rápidamente posible si la frase describía correctamente la escena o no. Los resultados mostraron que en adultos es posible adquirir significados verbales nuevos por co-ocurrencia entre acciones (movimientos) y formas lexicales nuevas. Diferencias de respuesta halladas entre tipos de frase durante el testeo permiten especular con respecto a los mecanismos involucrados en el proceso de decisión durante esta fase.; Infant language acquisition develops by simple exposure to the linguistic context, while in adults acquisition of the grammatical rules of a language requires explicit (i.e. conscious) learning processes. It has been shown that 4 to 8 month old infants can associate visual information with auditive information that has a linguistic form with only brief exposure times. The greater difficulty in adults in acquiring a second language by simple exposure may be in part due to difficulties in associating multiple sensory inputs with the adequate linguistic stimulus. We studied therefore the capacity in adults to assign meaning to new verbal forms by co-ocurrence between actions and new lexical labels. During training 60 different visual scenes were presented along with sentences formed by non-words that described the presented scenes. During the testing phase 40 new scenes were presented together with new sentences. In 50% of the cases the sentence described correctly the scene (Correct sentence), while in the remaining 50% the “verb” did not agree with the shown action (Incorrect sentence). Participants had to decide as fast and accurately as possible whether each sentence correctly described each visual scene. Results show that adults can assign new verbal meanings by co-occurrence between actions (movements) and new lexical labels. Differences in response patterns between both types of sentences during testing allow speculating about the mechanisms involved during the decision process in this phase.

Large neutral fractions in collisions of Li+ with a highly oriented pyrolytic graphite surface:Resonant and Auger mechanisms Bonetto, Fernando Jose; Romero, Marcelo Ariel; García, Evelina Andrea; Vidal, Ricardo Alberto; Ferron, Julio; Goldberg, Edith Catalina We report measurements of neutral atom fractions for Li+ scattered by a highly oriented pyrolytic graphite surface as a function of the incident ion energy and exit angle. We found an unexpected large neutralization probability that increases with both energy and exit angle. Based on a dynamical quantum calculation of the scattering process that accounts for the extended features of the surface and the localized nature of the atom-atom interactions, we propose that the resonant neutralization to the Li ground state is a relevant mechanism in this collision. However, to understand the whole process including the angular dependence, and taking into account the Li energy-level variations, we conclude that other mechanisms such as Auger neutralization to the ground state and resonant neutralization to excited states should also be considered.