Resistive switching in ferromagnetic La2/3Ca1/3MnO3 thin films Alposta, Ignacio; Kalstein, Ariel; Ghenzi, Néstor; Bengió, Silvina; Zampieri, Guillermo Enrique; Rubi, Diego; Levy, Pablo Eduardo Ferromagnetic thin films of La_{2/3}Ca_{1/3}MnO_{3} manganite were grown by pulsed laser deposition, under different oxygen atmospheres, on silicon substrates.We performed structural, magnetic, spectroscopic, and electrical characterization of the films. Resistive switching between high and low resistance states was obtained upon pulsing with opposite polarities voltages. The I-V curves exhibit sharp transitions between these states. The RS properties are strongly dependant on the films oxygen stochiometry and on the compliance current used for producing the high to low transition. ON/OFF ratios as high as 1000 were obtained for optimal RS conditions. Obtained results are discussed within the framework of mobile oxygen vacancies.

Effect of structural modifications on the drying kinetics of foods: changes in volume, surface area and product shape de Michelis, Antonio; Marquez, Carlos Alberto; Mabellini, Alejandra; Ohaco, Elizabeth; Giner, Sergio Adrian Macro and micro-structural changes take place during food dehydration. Macro-structural changes encompass modifications in shape, area and volume. Studies of such changes are important because dehydration kinetics (essential for calculating industrial dryers) may be highly influenced by changes in food shape and dimensions. The overall changes in volume, surface area (?shrinkage?) and shape (Heywood factor, with provides a close description of food shape) were determined experimentally, and the results were correlated with simple expressions. Hence, although dehydration kinetics can be modeled with simplified overall shrinkage expressions, the possibility of selecting a suitable geometry and predicting the characteristics dimensions will provide higher accuracy. An additional unresolved problem is the lack of a general model that predicts macro-structural changes for various foods and diverse geometries. In this work, based on experimental data of sweet and sour cherries, and rose hip fruits, a simplified general model to predict changes in volume and surface area are proposed. To estimate how the changes in characteristic dimensions affect the kinetic studies, experimental drying curves for the three fruits by means of a diffusional model considered the following variants for the characteristic dimensions: (i) The radius of the fresh food, assumed constant; (ii) The radius of the partially dehydrated product; (iii) The radius predicted by the correlation for structural changes, especially volume, obtained in this work and generalized for the three fruits, and (iv) to demonstrate the need to study the macro-structural changes for all dehydrated foods, also be present the case of a restructured food.

The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc Aragon, Eugenio; Pinotti, Lucio Pedro; D'eramo, Fernando Javier; Castro, Antonio; Rabbia, Osvaldo Miguel; Coniglio, Jorge Enrique; Demartis, Manuel; Hernando, Irene Raquel; Cavarozzi, Claudia Ernestina; Aguilera, Emilia Yolanda The collision of a divergent ocean ridge may evolve into two end cases: in the continuity of ocean-floor subduction, or in the detachment of the subducted plate. The northern Patagonia active plate margin has the unique situation that in Cenozoic time it has been subjected to two divergent ridge collisions, each one representing one of the end members. The Neogene Antarctica-Nazca divergent ridge collision evolved as a continuous ocean-floor subduction system, promoting a magmatic hiatus at the arc axis, the obduction of part of the ridge ocean-floor in the fore-arc, and basaltic volcanism in the back-arc. In contrast, the Paleogene Farallon-Aluk divergent ridge collision evolved into a transform margin, with the detachment and sinking of the Aluk plate and the development of a large slab window. As in the previous case, this collision promoted a magmatic hiatus at the arc axis, but the tectono-magmatic scenario changed to postorogenic synextensional volcanism that spread to the former fore-arc (basalt, andesite, rhyolite) and former back-arc (bimodal ignimbrite flare-up, basalt). Geochemistry of this slab window synextensional volcanism shows more MORB-like basalts towards the former fore-arc, and MORB-OIB-like basalts towards the former back-arc. Instead, an isolated undeformable crustal block in the former back-arc, with an ?epeirogenic? response to the slab window and extensional regime, was covered by OIB-type basalts after uplift. Major elements show that slab window basalts reach TiO2 values up to 3 wt%, as compared with the top value of 1.5 wt% of arc magmas. Besides, the MgO with respect to (FeOt + Al2O3) ratio helps to distinguish slab window magma changes from the former fore-arc to the former back-arc and also with respect to the ?epeirogenic? block. Higher contents of HFS elements such as Nb and Ta also help to distinguish this slab window from arc magmas and also, to distinguish slab window magma changes from the former fore-arc to the former back-arc and ?epeirogenic? block settings. The isotope compositions of slab window magmatism show a disparate coeval array from MORB to crustal sources, interpreted as a consequence of the lack of protracted storage and homogenization due to the extensional setting.

Evaluación del riesgo de impacto ambiental de plaguicidas en cultivos anuales del centro de Santa Fe; Assessment of pesticide environmental risks in annual crops in center of Santa Fe Arregui, Maria Cristina; Grenon, Daniel Arnaldo; Sánchez, D.; Ghione, J. Los plaguicidas permiten alcanzar la productividad y la sustentabilidad si se manejan adecuadamente. La elaboración de indicadores permite cuantificar el impacto ambiental de un fitosanitario. El objetivo de este trabajo fue determinar el impacto ambiental de plaguicidas sobre el suelo y el agua en lotes de agricultura del centro de Santa Fe con tres indicadores: GUS, Ipest e Índice relativo de Plaguicidas. El trabajo se realizó en 25 establecimientos cuyos registros de aplicaciones en cultivos de soja, maíz y trigo se relevaron entre 2007 y 2011. Se calcularon los tres indicadores y se compararon los resultados obtenidos. El maíz fue el cultivo con mayor riesgo de impacto ambiental por el uso intensivo de atrazina. En trigo y soja, los ingredientes activos empleados tuvieron bajo impacto ambiental. El empleo de indicadores contribuye a seleccionar plaguicidas con mejor comportamiento ambiental y realizar una planificación más sustentable de los cultivos.; Pesticides are essential tools to achieve productivity and sustainability in agricultural crops when they are applied minimizing undesirable effects. Pesticide environmental impact is related to toxicity and time of exposure. Several indicators allow the calculation of this impact: GUS, IPEST and Relative Pesticide Index. Our aim was the evaluation of pesticide environmental impact on soil and water in agricultural fields of Central Santa Fe with those three indicators. All pesticide treatments applied in soybean, wheat and corn in 25 farms were recorded from 2007 and 2011, also with soil properties and pesticide characteristics. Indicators were calculated and the results were compared. Corn has the highest risk of pesticide contamination in soil and water, related to the frequent use of atrazine. Wheat and soybean had less environmental impact. The application of indicators may be helpful for considering the use of new active ingredients and their relationship with sustainable systems.

Radiocarbon chronology of the early human occupation of Argentina Prates, Luciano Raúl; Politis, Gustavo Gabriel; Steele, James This paper reports the compilation and initial analysis of a database of 14C dates from archaeological sites in Argentina for the period 13,000 and 7000 14C BP. The spatial and temporal distribution of human occupation evidence during this period is surveyed, with discussion of potential sampling biases affecting the recognition of such sites in each region of Argentina. The archaeological signal of human occupation at the beginning of this period (13,000-11,000 14C BP) is suggestive but sparse, and weak. However, from about 11,000 14C BP there is a consistent archaeological signal. Most of the earliest occupation evidence comes from the eastern Pampas and from southern Patagonia. In the Chaco and Northeast regions, similarly early archaeological sites have not yet been detected. This contrast may reflect the actual distribution of early human occupation, but it may also reflect biased research effort and/or systemic factors affecting the visibility and level of preservation of the early archaeological record. In other regions such as the eastern slope of the Andes in Patagonia, the peri-Andean Central West, and the Northwest, where there has been intensive archaeological research for an extended period and there are fewer systematic factors which are likely to bias archaeological visibility, the absence of archaeological evidence of early occupation may indicate delayed colonization of these more marginal environments. The conclusion discusses the implications of 14C dates associated with Fishtail Projectile Points for the western hemisphere pre-Clovis debate, and the implications of terminal Pleistocene/early Holocene dated remains of extinct mammals for the megafaunal overkill hypothesis.

XRCC2 R188H (rs3218536), XRCC3 T241M (rs861539) and R243H (rs77381814) single nucleotide polymorphisms in cervical cancer risk Perez, Luis Orlando; Crivaro, Andrea Natalia; Barbisan, Gisela; Poleri, Lucía Belén; Golijow, Carlos Daniel Human Papillomavirus (HPV) is the main cause of cervical cancer and its precursor lesions. Transformation may be induced by several mechanisms, including oncogene activation and genome instability. Individual differences in DNA damage recognition and repair have been hypothesized to influence cervical cancer risk. The aim of this study was to evaluate whether the double strand break gene polymorphisms XRCC2 R188H G>A (rs3218536), XRCC3 T241M C>T (rs861539) and R243H G>A (rs77381814) are associated to cervical cancer in Argentine women. A case control study consisting of 322 samples (205 cases and 117 controls) was carried out. HPV DNA detection was performed by PCR and genotyping of positive samples by EIA (enzyme immunoassay). XRCC2 and 3 polymorphisms were determined by pyrosequencing. The HPV-adjusted odds ratio (OR) of XRCC2 188 GG/AG genotypes was OR = 2.4 (CI = 1.1-4.9, p = 0.02) for cervical cancer. In contrast, there was no increased risk for cervical cancer with XRCC3 241 TT/CC genotypes (OR = 0.48; CI = 0.2-1; p = 0.1) or XRCC3 241 CT/CC (OR = 0.87; CI = 0.52-1.4; p = 0.6). Regarding XRCC3 R243H, the G allele was almost fixed in the population studied. In conclusion, although the sample size was modest, the present data indicate a statistical association between cervical cancer and XRCC2 R188H polymorphism. Future studies are needed to confirm these findings.

Nuevos registros de Hippidion (Mammalia, Perissodactyla) en el Pleistoceno tardío de la Provincia de Buenos Aires, Argentina; New record of Hippidion (Mammalia Perissodactyla) from the late Pleistocene of Buenos Aires province, Argentina Prado, Jose Luis; Bonnini, R.; Alberdi, M. T.; Scanferla, Carlos Agustín; Pomi, Lucas Horacio; Fucks, Enrique Eduardo En este estudio se describen dos nuevos cráneos referidos a Hippidion principale (Lund) y varios elementos del esqueleto apendicular referidos a H. devillei procedentes de dos localidades clásicas de la provincia de Buenos Aires, las márgenes de los ríos Salado y Quequén Grande. Para la identificación taxonómica de los restos apendiculares, se realizó un análisis multivariante en el que se incluyeron los metacarpianos y falanges descritos y los registrados en varias localidades de Argentina y Brasil. Para la determinación de los cráneos se realizó un estudio comparativo con otros cráneos de diversas localidades.
Estos hallazgos incrementan el registro de Hippidion en América del Sur y aportan nuevas evidencias sobre la cronología de sus especies en Argentina. Se realizó una datación por AMS para el ejemplar de Río Salado (MHM-P54) que ha suministrado una edad 14C 14120 ± 50 BP. En general, los sedimentos portadores en ambas localidades son referibles a la Edad Lujanense, Biozona de Equus (Amerhippus) neogeus.; This study describes two new skulls referred to Hippidion(Lund) and various elements of the appendicular skeleton referred to H. devillei from two classic localities from Buenos Aires province: the Salado and Quequén Grande Rivers. For taxonomic identification of the appendicular remains was performed a multivariate analysis that included the metacarpals and phalanges described and several remains recorded in various locations in Argentina and Brazil. For the determination of the skulls was made a comparative study with other skulls from different localities. These data increasing the record of Hippidion in South America and provide new evidence about the chronological distribution of two species of Hippidion. One radiometric data was obtained by the method of AMS dating to the skull from Salado River (MHM-P54) about a 14C age 14120 ± 50 BP. In general, bearing sediments at both localities are referable to the Lujanian Age and the Biozone of Equus (Amerhippus) neogeus.

Trayectorias de relaciones en el marco de luchas étnico - territoriales en la Patagonia Argentina Crespo, Carolina Flavia; Tozzini, María Alma En este artículo abordamos los vínculos que se establecieron entre comunidades mapuches y algunas organizaciones sociales a partir de la conformación de reclamos étnico-territoriales en Lago Puelo –noroeste de la provincia de Chubut, Patagonia Argentina–. En particular, analizamos las relaciones que se entablaron con organizaciones indígenas mapuche-tehuelche y con una organización socio-ecologista no indígena. Esta trama de relaciones está dando textura y sentido a la dinámica que ha adoptado la auto-adscripción indígena, las memorias activadas y las formas de lucha.; In this article we examine some of new links established between Mapuche communities and social organizations from the conformation of ethno-territorial claims in Puelo Lake –northwest of the province of Chubut, Patagonia Argentina–. In particular, we analyze the relationships that had been engaging with indigenous mapuche – tehuelche organizations and a socio- ecological non-indigenous organization. This relationships are giving texture and sense to the dynamics that has adopted the indigenous self-identification, the activated memories and the tested forms of struggle.; Dans cet article, nous abordons les liens établis entre les communautés mapuches et les organisations sociales, comme consequence des revendications ethno-territoriales au Lago Puelo, au nord-ouest de la province du Chubut, dans la Patagonie Argentine. En particulier, nous analysons les rapports qui ont été établies entre des indigènes Mapuche-tehuelche avec une organisation socio-écologique non autochtone. Ce réseau de relations veut donner un sens à la texture et la dynamique qui ont adopté les auto-attributions indigènes, les mémoires activées et les formes de lutte.

Turbidimetric Behavior of Colloidal Particles in Beer Before Filtration Process Benitez, Elisa Ines; Martinez Amezaga, Nancy María Jimena; Sosa, Gladis Laura; Peruchena, Nelida Maria; Lozano, Jorge Enrique The effect of colloidal particles and yeast on turbidity of Pilsen beer before the filtration process was studied in this work. The colloidal particles are mainly composed of polysaccharides, representing 96.89 %, in second place proteins with a concentration close to 2 %, and polyphenols less than 0.3 %. There is also a very low concentration of yeast (;lt;0.25 %). The presence of different types of particles in the sample caused multimodal histogram in the particle size distribution and four distinct zones were identified: (1) very small individual particles (D = 0.06μm),(2) yeast(D = 3μm) (3) colloidal aggregates (D = 17μ), and (4) a zone with a high dispersion of size, with two D Values (101 and 200 μm). Particles size counts well correlate with both the scanning electron microscopy (SEM) digital image analysis, and the turbidity determination. The fractal dimension (Df) of the aggregates was determined by analyzing the SEM images with the Variogram method, obtaining Df > 2.4 values. Those values are typical of aggregates formed by rapid flocculation or diffusion limited aggregation. Results of this study support the formulation of a model valid for the prediction of colloidal particles concentration in beer. © 2012 Springer Science+Business Media, LLC.

China: el país de los senderos que se bifurcan Rapoport, Mario Daniel La noción de países emergentes la plantea, para el siglo XIX, Paul Bairoch en Mythes et paradoxes de l’histoire économique, a fin de rebatir la idea de que solamente reinaba entonces la pax britannica. Por un lado, reconoce la importancia del imperio británico y la existencia de una división internacional del trabajo basada en el libre cambio, con el liderazgo y monopolio industrial del Reino Unido y la participación en él de países proveedores de alimentos o materias primas, como la Argentina. Pero, dice Bairoch, había también países emergentes, proteccionistas e industrialistas, como los Estados Unidos y Alemania, que hacia fines de siglo superaban ya en producción, innovaciones tecnológicas e incluso en el intercambio de muchos productos, a la primera gran metrópoli industrial. Según Bairoch, el que hoy llamamos mundo desarrollado, salvo Gran Bretaña, era un “océano de proteccionismo”, mientras que aquellos países que giraban en la órbita británica, como la Argentina, se habían convertido en un “océano de liberalismo”.

La regulación de los servicios de agua y saneamiento en el área metropolitana de Buenos Aires (AMBA), Argentina; Water and drainage services regulation at the Metropolitan area of Buenos Aires (AMBA), Argentina Minaverry, Clara María; Caceres, Veronica Lucia El presente trabajo centra la atención en las convergencias y diferencias que asumen los esquemas regulatorios que coexisten en el el Área Metropolitana de Buenos Aires AMBA. Para lo cual en primer lugar, se presentan algunos aspectos metodológicos que encuadran el análisis; en segundo se realiza una caracterización del territorio en estudio y de las particularidades de los servicios; y en tercer lugar, se caracterizan aspectos regulatorios y se reflexiona sobre los desafíos de la expansión de la cobertura. Metodológicamente, se recurrió a la observación documental de doctrina, legislación e informes de las empresas de agua; y desde el punto de vista cuantitativo, se analizaron los datos del Censo Nacional de Población, Vivienda y Hogares de los años 2001 y 2010. En lo que concierne a la provisión de agua y saneamiento, el territorio se encuentra bajo el área de prestación de dos empresas principales de gestión pública: una bajo jurisdicción de la Nación: Agua y Saneamientos Argentinos S.A. (en adelante AySA) creada en 2006 y otra bajo la órbita de la PBA: Aguas Bonaerense S.A. (en adelante ABSA) creada en 2002. Estas empresas fueron constituidas tras la salida de los operadores privados: Aguas Argentinas S.A. y Azurix S.A. respectivamente. Dichos operadores ingresaron al sector en la década del noventa y tras incumplimientos reiterados en las metas de inversión, problemas de calidad, etc. sus contratos fueron rescindidos y tanto el Estado nacional como provincial optaron por re-estatizar los servicios.Se concluye que: a) la cobertura de los servicios expresa niveles de desigualdad territorial significativos, y que la universalización ha sido contemplada legalmente en los marcos regulatorios, aunque en el caso de ABSA sin estipular un plazo temporal para lograrla; b) los marcos que regulan a las empresas del AMBA no acuerdan sanciones a los incumplimientos legales a las obligaciones asumidas por las empresas prestarías de los servicios; c) existe un solapamiento normativo ya que la concesión de AySA incluye a municipios pertenecientes a la Provincia de Buenos Aires (que ya han sido mencionados anteriormente), respecto de los cuales se les podría aplicar diversa normativa que en muchos casos es contradictoria.; We focus our attention at the convergences and differences of Buenos Aires Metropolitan Area AMBA regulation. In the first place, we present some methodological aspects in connection with our analysis, in the second place we make a characterization of the territory study and of the services features, and in the third place; we analyze regulatory issues and reflect about coverage expansion challenges. Methodologically, we observed documents: jurisprudence, regulations and water companies reports, and from a quantitative point of view, we analyzed information from the Population and Housing National Census of 2001 and 2010. The territory is under water and drainage provision supplied by two main public companies; one of national jurisdiction: Agua y Saneamientos Argentinos S.A. (AySA) which was created in 2006, and the other one under the Buenos Aires Province jurisdiction (ABSA) which was created in 2002. These two companies appeared after the private operators exit: Aguas Argentinas S.A. and Azurix S.A. respectively. Both joined the water area in the nineties and after continuously unfulfilments of investment goals, quality problems, etc, their agreements were terminated and the National and Provincial governments chose to re-nationalize these services. We can conclude that: a) the services coverage show important territorial inequalities and that universalization have been included by regulation, but in the case of ABSA it does not fix a temporal period; b) these legal frameworks regulate the AMBA companies, but do not incorporate sanctions for legal unfulfilments produced by water companies; c) there is a legal overlapping, because the AySA concession provides water and drainage services to local governments from Buenos Aires Province (which were mentioned before), where could be applied different regulations which sometimes contradict each other.

Vas uacuum et signatum: la imagen del judío en los Dialogi y el problema de la autoría gregoriana Laham Cohen, Rodrigo Jaime El presente trabajo se centra en el estudio de la imagen de los judíos presente en los Dialogi, obra tradicionalmente atribuida a Gregorio Magno pero sujeta a un amplio debate en torno a su autoría, ya desde la temprana modernidad pero, sobre todo, a partir de la obra de Francis Clark. En primer lugar, realizamos un análisis minucioso del único exemplum en el que un judío es protagonista, intentando poner en relación las coordenadas espacio-temporales de la narración, con los datos provenientes del Registrum epistularum gregoriano. A partir de tal aproximación, investigamos si la imagen de los hebreos presentada en los Dialogi es coherente con el modo en el que son exhibidos en las obras gregorianas de corte teológico. De este modo, creemos aportar un nuevo elemento al debate sobre la autoría de los Dialogi.; The aim of our paper is to analyze the way the Jews are portrayed in the Dialogi. This piece, traditionally attributed to Gregory the Great, was subject of debate about its true authorship since the early modernity and, especially, from Francis Clark’s work. In order to address this problem, we will carry out a meticulous analysis of the only exemplum in which the actor is a Jew, contrasting the coordinates of this story with the information obtained from the Gregorian Registrum epistularum. As a second step, we will investigate to what extent the image of the Hebrews from the Dialogi matches or not with the one presented in the Gregorian theological works. We consider this procedure will allow us to contribute with a new element to the debate on the Gregorian authorship of the Dialogi, as well as achieve an in-depth look at the issue of the image of the Jews in Gregory’s work.; Le but de cet article est de présenter l’image des juifs dans une œuvre connue sous le nom de Dialogi, dont l’attribution à Grégoire le Grand a été contestée depuis la modernité et surtout aujourd’hui après les recherches de Francis Clark. En premier lieu, notre recherche s’attaque à l’étude du seul exemplum ayant un juif comme protagoniste, pour le mettre en rapport avec les données du Registrum epistolarum de Grégoire. Nous étudions ensuite les rapports entre l’image des juifs dans les Dialogi et celle qui est présentée dans les œuvres grégoriennes à portée théologique. Nous espérons ainsi apporter de nouveaux éléments à la discussion sur l’auteur des Dialogi et obtenir un aperçu approfondi de l’image des juifs dans l’œuvre de Grégoire.

Análisis de 12 años de medición de un fotómetro solar instalado en Falda del Carmen, provincia de Córdoba; Analysis of 12 years measurements of an aeronet sunphotometer installed in Falda del Carmen, province of Cordoba Otero, Lidia Ana; Ristori, Pablo Roberto; Pallotta, Juan Vicente; Pawelko, Ezequiel Eduardo; D'elia, Raul Luis; Quel, Eduardo Jaime El objetivo fundamental de este trabajo es determinar el tipo de aerosoles que caracteriza la región centro-norte de la Argentina, su comportamiento y su variabilidad interanual. Para ello se presenta un análisis estadístico de los datos obtenidos con un fotómetro solar que estuvo en funcionamiento durante doce años, (1999 - 2010), en la estación Córdoba – CETT de AERONET (NASA) instalada en el Centro Espacial Teófilo Tabanera, (31,5º S; 64,5º O) en Falda del Carmen, provincia de Córdoba. Se comparan estos resultados con los obtenidos en trabajos anteriores, realizados con un conjunto de datos correspondiente a los años 2000 y 2001. Se estudia la representatividad de las mediciones, su evolución y cambios que ha sufrido la región en los últimos años en cuanto a su carga aerosólica.; The objective of this work is to determine the type of aerosols that characterizes the north-central region of Argentina, their behavior and interannual variability. This paper presents a statistical analysis of the data obtained with solar photometer was in operation for twelve years (1999 - 2010) in Córdoba station - CETT AERONET (NASA) installed in the Teófilo Tabanera Space Center, (31.5 ° S, 64.5 ° W) in Falda del Carmen, province of Cordoba. The results are compared with those obtained in previous work, performed with a data set for the years 2000 and 2001. The representativeness of the measurements, their evolution and the changes that the region has experienced during recent years in terms of aerosol load are studied.

Cylindrical wormholes with positive cosmological constant Richarte, Martín Gustavo We construct cylindrical, traversable wormholes with finite radii by taking into account the cutand-paste procedure for the case of cosmic string manifolds with a positive cosmological constant. Under reasonable assumptions about the equation of state of the matter located at the shell, we find that the wormhole throat undergoes a monotonous evolution provided it moves at a constant velocity. In order to explore the dynamical nonlinear behaviour of the wormhole throat, we consider that the matter at the shell is supported by anisotropic Chaplygin gas, anti-Chaplygin gas, or a mixed of Chaplygin and anti-Chaplygin gases implying that wormholes could suffer an accelerated expansion or contraction but the oscillatory behavior seems to be forbidden.

Modeling natural photic entrainment in a subterranean rodent (Ctenomys aff. knighti), the tuco-tuco Flôres, Danilo E. F. L.; Tomotani, Barbara M.; Tachinardi, Patricia; Oda, Gisele Akemi; Valentinuzzi, Verónica Sandra Subterranean rodents spend most of the day inside underground tunnels, where there is little daily change in environmental variables. Our observations of tuco-tucos (Ctenomys aff. knighti) in a field enclosure indicated that these animals perceive the aboveground light-dark cycle by several bouts of light-exposure at irregular times during the light hours of the day. To assess whether such light-dark pattern acts as an entraining agent of the circadian clock, we first constructed in laboratory the Phase Response Curve for 1 h light-pulses (1000lux). Its shape is qualitatively similar to other curves reported in the literature and to our knowledge it is the first Phase Response Curve of a subterranean rodent. Computer simulations were performed with a non-linear limit-cycle oscillator subjected to a simple model of the light regimen experienced by tuco-tucos. Results showed that synchronization is achieved even by a simple regimen of a single daily light pulse scattered uniformly along the light hours of the day. Natural entrainment studies benefit from integrated laboratory, field and computational approaches.

Low-Dimensional magnetic systems in nanopore arrays Bajales Luna, Noelia; Viqueira, María Soledad; Avalle, Lucia Bernardita; Urreta, Silvia Elena; Bercoff, Paula Gabriela FeCo nanowires 20 nm diameter are synthesized by AC electrodeposition using AAO membranes as templates. The hysteresis and structural properties of the as deposited nanowire arrays are characterized. The orientation dependence of the coercive field measured in the array is compared with the predictions of a magnetization reversal model involving the nucleation and propagation of a transverse wall. The model is promissory because it predicts the experimental curve shape quite well.

Hysteresis properties of hexagonal arrays of FePd nanowires Viqueira, María Soledad; García, Sebastián Eduardo; Urreta, Silvia Elena; Pozo Lopez, Gabriela del Valle; Fabietti, Luis Maria Rodolfo FePd nanowires (NWs) with different compositions have been grown into anodized aluminum oxide templates (AAO) by AC electrodeposition at room temperature. The effects of nanowire composition and morphology on the hysteresis properties of the ordered array of NWs are investigated. All the NWs are polycrystalline; the Fe-rich wires have a bcc structure while the Pd rich ones are fcc. FePd NWs are ferromagnetic and the spontaneous magnetization is found to be parallel to the nanowire long axis (out of plane easy axis) and both, the saturation polarization and the coercive field increase with the iron content.

Historia/Histoire(s). Las imágenes de Walter Benjamin y Jean-Luc Godard; Histories/Histoire(s). Images of Walter Benjamin and Jean-Luc Godard Taccetta, Natalia Roberta A partir de Histoire(s) du cinéma de Jean-Luc Godard, se intenta revisar algunas nociones fundamentales de la filosofía de la historia de Walter Benjamin. Esto implica volver sobre la importancia del montaje como mecánica historiadora y sobre el modo en que la re-escritura de la historia posibilita miradas políticamente informadas más acordes con la “historia a contrapelo” benjaminiana. En este sentido, se vuelve ineludible la noción de “ruina” que permite volver sobre la mirada heterodoxa de Benjamin, opuesta a los sentidos históricos únicos y la racionalización teleológica de los acontecimientos.; Taking as our starting point Jean-Luc Godard´s film Histoire(s) du cinéma, we intend to review some basic concepts of Walter Benjamin’s philosophy of history. This implies the return to montage as a historic procedure and also to the way in which the re-writing of history enables new political views according to the benjaminian notion of “history against the grain”. In this sense, it becomes unavoidable the notion of “ruin” that allows an unorthodox look at History, different from those which propose a single historical meaning or the teleological rationalization of events.

Export emergence of differentiated goods from developing countries: Export pioneers and business practices in Argentina Artopoulos, Alejandro; Friel, Daniel; Hallak, Juan Carlos This study explores the underlying factors that enable firms from developing countries to successfully export differentiated goods to developed countries. The article describes four case studies of export emergence in differentiated-good sectors in Argentina, namely wine, television programs, motorboats, and wooden furniture. The case studies rely primarily on an extensive set of interviews. We find that consistent exporters to developed countries adopt a new set of business practices that differ starkly from those that prevail in their domestic market. In three of the sectors, an export pioneer led the adoption of these new practices. Export pioneers possessed tacit knowledge about foreign markets, achieved through their previous embeddedness in the business community of those markets. Export emergence occurs as business practices diffuse throughout the sector. These findings point to the importance of foreign market knowledge, relative to production knowledge, as the key constraint to achieve consistent export to developed countries.

Historiografía y educación peronista: un estado de la cuestión sobre historia de la educación durante el primer peronismo Perrupato, Sebastian Domingo El presente artículo tiene por objetivo indagar y analizar la producción historiográfica sobre la educación durante el primer peronismo. Entendemos que la misma ha sido el resultado de la reapertura democrática y que su producción resulta aún hoy una cantera abierta de recursos y documentos historiográficos que esperan ser explorados y analizados por generaciones futuras.; This article aims to investigate and analyze the historiographical production about education during the first Peronist. We understand that it has been the result of the return to democracy and that their production is still today an open quarry historiographical resources and documents waiting to be explored and analyzed by future generations.