Experiencia didáctica en el aula de ciencia: el suelo como integrador de conceptos químicos; Teaching experience in the classroom of science: the soil as chemical thread concept Moro, Lucrecia E.; Tintori Ferreira, María Alejandra; Lorenzo, Maria Gabriela En este trabajo presentamos una propuesta didáctica innovadora para alumnos de la Educación Secundaria, sobre le tema suelo en la cual se tiene en cuenta el impacto de la actividad humana. Esta propuesta se implementó durante el desarrollo del tema disoluciones y ofreció una nueva alternativa para la interpretación de los conceptos de disolución y de pH. Se relacionaron los compuestos químicos con los agentes formadores del suelo y sus contaminantes. La experiencia didáctica se desarrolló simultáneamente en cinco escuelas de la Provincia de Buenos Aires empleando una metodología “en red” en el marco del Programa “Ciencia entre Todos” (CET). Presentamos la propuesta didáctica por su carácter innovador para el tratamiento de los diseños curriculares de química, por su enfoque integrador con las problemáticas sociales de la región y la promoción del cuidado del ambiente desde el punto de vista del desarrollo sustentable.; We present a new didactic approach for secondary students about “the soil”. The impact of the human activity was especially considered. This design was carried out for solutions and provided new strategies for understanding pH concept. Chemical compounds were related with the training agents of the ground and its pollutant. This didactic experience was simultaneously put into practice in five schools of Provincia de Buenos Aires employing net methodology. This belongs to the Program “Science by and for Everyone” (CET). We present this proposal because of its innovation characteristics for chemical contents, its focus on social and regional problems and the promotion of environment care from sustainable development perspective.

Recombinant horseradish peroxidase production in species of lepidoptera frequently found in Argentina Romero, Lucía Virginia; Targovnik, Alexandra Marisa; Wolman, Federico Javier; Fogar, M.; Simonella, M.; Cascone, Osvaldo; Miranda, Maria Victoria Horseradish peroxidase isozyme C (HRPC) is an important commercial biocatalyst. In this study, a screening of different lepidopteran species frequently found in Argentina to produce this protein was carried out. Two recombinant viruses were constructed: AcMNPV HRPC polyhedrin-minus (occ−), an intrahemocelical infective virus; and AcMNPV HRPC polyhedrin-plus (occ+), to achieve an oral infective baculovirus. Each lepidopteran species was infected either with AcMNPV HRPC occ− or AcMNPV HRPC occ+ and the harvesting days post-infection (dpi) were optimized. All species were susceptible to AcMNPV HRPC occ− infection, giving Spodoptera frugiperda the best yield: 41 μg per larva. Rachiplusia nu was highly susceptible to oral infection, reaching 22 μg per larva at 4 dpi. HRPC was purified by IMAC from S. frugiperda extracts with a yield of 86% and a purification factor of 29.

Factores que afectan el éxito reproductivo y la calidad de la nidada del pingüino patagónico (Spheniscus Magellanicus) en el Canal Beagle, Tierra del Fuego, Argentina; Factors affecting reproductive success and clutch quality of Magellanic Penguin (Spheniscus Magellanicus) in the Beagle Channel, Tierra del Fuego, Argentina Scioscia, Gabriela; Raya Rey, Andrea Nélida; Favero, Marco; Schiavini, Adrian Carlos Miguel En este estudio se estimó la duración de los viajes de alimentación y el tamaño corporal de machos y hembras del pingüino patagónico durante el período reproductivo en una colonia del Canal Beagle, Tierra del Fuego, y se determinaron las implicancias de estos parámetros sobre el éxito reproductivo y la calidad de la nidada. La duración de los viajes difirió significativamente entre sexos y entre las distintas etapas reproductivas. Las hembras realizaron viajes más extensos que los machos durante la etapa de incubación. Esto podría deberse a diferencias en las reservas corporales y en capacidades de alimentación relacionadas con su condición corporal. En ambos sexos, los viajes realizados durante la etapa de incubación fueron más prolongados, mientras que los realizados durante el cuidado temprano de pichones fueron más cortos. Los viajes de alimentación tuvieron menor duración cuando los pichones eran más pequeños y necesitaban de un mayor cuidado parental. Se registró un alto valor de éxito reproductivo (1.51 pichones por nido) comparado con el de colonias de las Islas Malvinas y Punta Tombo. Estos resultados podrían explicarse por diferencias en la disponibilidad de alimento en aguas cercanas a la colonia. El tamaño corporal de los padres no se relacionó con el éxito reproductivo. No obstante, las hembras con mayor tamaño corporal produjeron pichones de mayor tamaño al comienzo de la muda y nidadas de mayor calidad. La correlación positiva entre el tamaño de la hembra y el tamaño de los pichones al comienzo de la muda sugiere un aporte importante de las hembras en el desarrollo del pichón.; The aim of this work was to study foraging trip duration and body size of male and female Magellanic Penguins during the breeding season and to determine the association of these parameters with both reproductive success and clutch quality in a colony located in the Beagle Channel, Tierra del Fuego. Trip duration differed significantly between sexes and between breeding stages. Females performed longer trips than males during incubation. We suggest that this could be due to differences in body reserves and foraging capabilities related with their body condition. In both sexes, foraging trips during incubation were longer than in the other stages, while the shortest trips were observed during early chick rearing. Trips were shorter when chicks were smaller and required greater parental care. A high value of reproductive success (1.51 chicks per nest) was recorded in comparison to that observed in colonies from the Malvinas Islands and Punta Tombo. These results could be related to differences in food availability in nearby waters. Body size of parents was not associated with reproductive success. Notwithstanding, larger females produced larger chicks at early moult and clutches of higher quality. The correlation between female body size and chick size at early moult suggests an important contribution of females on chick's development.

Synthesis and Characterization of superparamagnetic Iron Oxide Nanoparticles for bio-medical applications Cano, Leonardo Andres; Cagnoli, Maria Virginia; Stewart, Silvana Jacqueline; Cabanillas, Edgardo Domingo; Romero, E. L.; Marchetti, Sergio Gustavo Monodisperse iron oxide nanoparticles (NPs) of 4 nm were obtained through high-temperature solution phase reaction of iron (III) acetylacetonate with 1, 2-hexadecanediol in the presence of oleic acid and oleylamine. The as-synthesized iron oxide nanoparticles have been characterized by X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and magnetic measurements. The species obtained were Fe3O4 and/or γγ -Fe2O3. These NPs are superparamagnetic at room temperature and even though the reduced particle size they show a high saturation magnetization (MS ≈ 90 emu/g).

As estatísticas como objeto de estudo González Bollo, Hernán Gustavo De 12 a 15 de novembro de 2010, a “Sociedade Brasileira de História da Ciência” (SBHC), estará promovendo seu 12º Seminário Nacional de História da Ciência e da Tecnologia, na cidade de Salvador, nas dependências da Universidade Federal da Bahia. Junto, tendo por objetivo precípuo a reativação da “Sociedade Latino-Americana de História da Ciência e da Tecnologia”, estará sendo realizado seu 7º Congresso. Pois este ano, pela primeira vez, haverá um simpósio focalizando as estatísticas como objeto de estudo, e não como meio de análise: “As instituições estatísticas oficiais: conceitos, medições, comunidades profissionais e a criação de políticas públicas”. Foi uma idéia de Nelson de Castro Senra, que logo recebeu aceitação entusiástica de Hernán González Bollo, quando, então, ambos passaram a trabalhar em colaboração, elaborando a proposta enviada à SBHC.

Bordes dinámicos sobre el método de Lattice Boltzmann para simulación de superficies de fluidos en tiempo real Garcia Bauza, Cristian Dario; Lazo, Marcos Gonzalo; Boroni, Gustavo Adolfo; Dalponte, Diego David; Clausse, Alejandro Un problema típico en flujos en geometrías complejas son los bordes móviles, como por ejemplo en la simulación de flujo de sangre en arterias o el movimiento de un barco. En este trabajo se presenta una implementación especial en un autómata de Lattice Boltzmann 2D de aguas superficiales con bordes y obstáculos internos móviles. El esquema permite simular en forma flexible escenarios de ondas superficiales producidas por embarcaciones, reflejos en puentes, y otras situaciones de interés en animación.

Environmental risks, demographic dynamic and Life Quality: Argentina at beginning of XXI century Velázquez, Guillermo Ángel In this work we analyze the relationship among: 1) Certain environmental risks: Flood problems, Earthquakes, Tornadoes and Soil degradation, 2) Demographic dynamics (inter census growth and migratory balances) and 3) Grade of Life Level Quality of Argentinian people. We use a Geographical Information System (GIS) in which we have done the digitalization of the respective layers of environmental risks. Following, we examine the information on demographic dynamics. At last, we present a synthetic index of the population’s Life Quality, which was elaborated starting from a combination of weighted indicators of environmental and socioeconomic dimensions (education, health and housing). The next step is to study the demographic behaviour and the grade of well-being of Argentina’s people different segments for each one of the environmental risks. We start from an operation of overlapping of different layers (for example: flood risk, growth rate, migration balance, etc). All previous stepladder let us size and compare the obtained Life Quality Index with Demographic Dynamics according to the degree of affectation of each one of the considered physical-environmental events. Finally we can establish the future scenario by projecting these phenomena impacts into the process of global environmental change.

O resultado do conhecimento no segundo comentário de Boécio à Isagogé de Porfírio Bertelloni, Carlos Francisco Uma pequena parte do corpus textual conhecido como Aristoteles latinus foi chamado pelos medievais de Logica vetus. Esta era constituída pelas Categorias e o Perí hermeneias, de Aristóteles, pela Isagogé de Porfírio e pelos comentários de Boécio às obras de Aristóteles e de Porfírio. Hoje é indiscutível a importância dos comentários neoplatônicos da Antiguidade tardia para a compreensão dos textos de Aristóteles. Dentro desse programa neoplatônico, os comentários deste também contribuíram para essa compreensão. No caso de Boécio produz-se, contudo, um fenômeno paradoxal, porque, apesar de seu neoplatonismo, em seu segundo comentário à Isagogé de Porfírio, Boécio conseguiu formular uma das interpretações mais profundas do pensamento aristotélico concernente ao resultado de nossa atividade cognitiva. No segundo comentário, Boécio procede por três passos: 1) analisa as três perguntas sobre os universais, formuladas por Porfírio; 2) realiza uma aporia do modo pelo qual Porfírio resolve o problema dos universais; e 3) apresenta sua própria posição acerca dos universais, que é diversa da posição de Porfírio.

Producción ovina extensiva en la Patagonia Austral: el caso de la zona centro de Santa Cruz Andrade, Larry Dennys; Bedacarratx, Valeria de Los Ángeles; Alvarez, Roberto El propósito del artículo consiste en analizar la meseta central de Santa Cruz en sus aspectos socioproductivos. El objetivo de la investigación, de la cual este trabajo es una elaboración parcial, se orienta a establecer la viabilidad del modelo vigente en la región -ovino extensivo-, así como las posibilidades de que las prácticas asociativas se constituyan en el eje articulador de un relanzamiento productivo. Aquí presentamos un primer análisis socioeconómico y productivo con la finalidad de definir el escenario en el que actualmente se lleva adelante la producción ovina extensiva. Incluimos una descripción de los nuevos actores que actualmente operan en el centro-norte de la provincia y, especialmente en nuestra área de estudio, destacándose entre ellos las empresas mineras transnacionales.; The intention of the article is to analyze the central plateau of Santa Cruz in its socio-productive aspects. The main aim of the investigation, from which this work is a partial elaboration, is to establish: on the one hand, the viability of the traditional extensive ovine model in the region; on the other hand, the possibilities that the associative practices have to become the articulador axis of a productive relaunching. Here, we present a first socioeconomic and productive analysis in order to define the scene in which, at the moment, the extensive ovine production takes ahead. We include a description of the new actors who, nowadays, operate in the area of study, standing out among them, the transnational mining companies.

La conformación de nuevas teorías sobre el arte latinoamericano en el proceso de crisis epistemológica de la modernidad Serviddio, Luisa Fabiana El Mayo francés y la entrada de los tanques soviéticos a Praga señalaron simbólicamente el año de 1968 como el momento de apogeo de una crisis –política, socioeconómica, culturalque relativizó los principales proyectos occidentales del siglo XX. En el campo del arte latinoamericano en se trató de un momento de transición, en el que se reformularon algunas respuestas en nuevos términos, y se anticiparon desarrollos teóricos posteriores. Los críticos, transformados en teóricos, ubicaron sus reflexiones dentro de una temporalidad predictiva –la futurología de Romero Brest- y prescriptiva –el pensamiento visual independiente de Acha, o la resistencia de Marta Traba-, buscando figurarse hacia adonde iban las prácticas artísticas de la región.

Música y memoria: La representación del detenido-desaparecido en la industria cultural de la Argentina reciente Quiña, Guillermo Martín En el presente trabajo abordamos la problemática de la representación de los detenidos-desaparecidos por la última dictadura militar argentina en un producto mercantil cultural concreto: la música. Se trata de una indagación acerca de las características que dicha representación asume, preguntándonos por diversas especificidades que hacen a la industria cultural en tanto tal, a la música como producción simbólica y a los modos de su inscripción en la historia reciente de una lucha política concreta. ¿Qué relevancia analítica asumen las condiciones materiales de existencia de la obra musical en la representación del detenido-desaparecido? ¿Qué vínculo establece la obra musical con su propia condición de producto social? ¿Cómo indagar la relación inherente a la obra musical en tanto producto artístico y objeto mercantil? Intentamos reflexionar críticamente acerca de diversos aspectos que constituyen la relación entablada entre las mercancías culturales en sentido amplio y musicales en particular, y los sujetos colectivos históricos involucrados, atendiendo al carácter industrial que asumen hoy aquellas. Se trata de una reflexión que pretende abonar a la construcción de un interés analítico sobre las transformaciones del campo musical local en los últimos años por parte de las ciencias sociales.; In this paper we approach the issue of the representation of disappeared and detained people during the last military dictatorship in Argentina in a concrete cultural and merchant product: music. We look for the characteristics that representation assumes, focusing the different specifications of cultural industry, of music as symbolic production and of the modalities of its presence into the recent history of a particular politic struggle. What is the relevance of material conditions of the existence of musical work on disappeared and detained people representation? Which relation does music establish with its own social product condition? How we should ask about the double condition of music, as an art object and a commodity? We try to think critically about diverse aspects which constitute the relation between cultural and musical commodities, on one side, and collective actors involved, on the other. With this reflection we try to contribute to build an analytic interest on recent changes of the local music field by social sciences.

The surface organization of diacylglycerol pyrophosphate and its interaction with phosphatidic acid at the air-water interface Villasuso, Ana Laura; Wilke, Natalia; Maggio, Bruno; Machado, Estela Edelmira Diacylglycerol pyrophosphate (DGPP), a phosphorylated form of phosphatidic acid (PA), gained attention recently due to its role as signaling lipid. However, little is known about its surface organization and potential impact on membrane-mediated function. In this work we investigated the interfacial behavior of Langmuir monolayers formed with pure DGPP and of its mixtures with PA. We found that changes of the subphase pH affect the surface behavior of DGPP. At pH 8, DGPP forms liquid expanded monolayers with a compressibility modulus of about 60 mN m−1 at collapse. On acidic solutions, the compressibility modulus increases to 90 mN m−1 and the average molecular area is smaller. At pH 8, DGPP and its precursor PA form thermodynamically favored topographically homogeneous non-ideal mixtures. The interaction among these lipids leads to a non-ideal diminution of the mean molecular area and consequently, to an increase of the compressibility modulus, with variations of the surface electrostatics. The favorable interaction of PA and DGPP, leading to changes of the film packing suggest that DGPP may act as a structural signal transducer in membrane-mediated cellular processes.

Role of the quorum sensing mechanism in the response of pseudomonas aeruginosa to lethal and sublethal UVA irradiation Costa, Cristina Susana; Pezzoni, Magdalena; Fernández, Rubén O.; Pizarro, Ramón Augusto The role of quorum sensing (QS) in the response of Pseudomonas aeruginosa to UVA radiation was investigated in the PAO1 strain and derivatives defective in the synthesis of the QS signals 3OC12-HSL (lasI strain), C4-HSL (rhlI strain) or both (lasI rhlI strain). Cell viability measurements demonstrated that the double mutant was significantly more sensitive to UVA than single mutants, which in turn showed reduced cell survival with regard to the PAO1 strain. Irradiation under nitrogen atmosphere and chemiluminescence measurements indicated the oxidative nature of the UVA-induced damage. The activity of the antioxidant enzymes catalase and superoxide dismutase was assayed in these strains before and after irradiation, and a strong correlation between catalase levels and UVA sensitivity was observed. When a sublethal UVA dose was applied to PAO1, a growth delay was observed and this mechanism depended on the rhl system. Moreover, low doses of UVA irradiation triplicated the level of C4-HSL in log PAO1 cells. It is concluded that QS is fundamental in the defense against the toxic effects of UVA in P. aeruginosa. The induction of the QS system by UVA independently of cell density could function as an adaptative strategy to withstand this hostile environmental condition.

Supervivencia de Hogna sp. (Araneae: Lycosidae) depredada por Leptodactylus ocellatus Giambelluca, Luis Alberto; Rodríguez, Raúl; Arias, Daniel; Gonzalez, Alda El objetivo del trabajo es dilucidar la supervivencia de arañas Lycosidae depredadas por ranas Leptodactylidae y si existe o no mecanismos de defensa por parte de las arañas dentro del estomago de la rana, como así establecer el tiempo de sobrevida.

Chelation Therapies: A Chemical and Biochemical Perspective Baran, Enrique José Chelation therapy occupies a central place in modern medicine and pharmacology, beacuse continuous studies with laboratory animals and extensive clinical experience demonstrate that accute or chronic intoxications with a variety of metals can be considerable improved by administration of a suitable chelating agent. In this review the chemical characteristics, properties and uses of the most common chelating agents as well as those of some new and very promising agents of this type, are discussed. In the second part of the review the biological and biochemical impact of these agents, as well as their use for the treatment of some selected diseases and disorders, are also analyzed and discussed in detail.

Trophic dynamics of three sympatric anuran species in a soybean agroecosystem from Santa Fe Province, Argentina Peltzer, Paola; Attademo, Andres Maximiliano; Lajmanovich, Rafael Carlos; Junges, Celina Maria; Beltzer, Adolfo Hector; Sanchez, Laura Cecilia The conversion of forests to agroecosystems presents a challenge for biodiversity conservation. In this study, the feeding habits of three species of anurans (Rhinella fernandezae, Odontophrynus americanus and Physalaemus albonotatus) were comparedRhinella fernandezae, Odontophrynus americanus and Physalaemus albonotatus) were compared between a soybean field and a native forest in Santa Fe Province, Argentina. Our dietary assessment is based on 124 individuals (47 R. fernandezae, 45 O. americanus and 32 P. albonotatus). Lepidopteran larvae were the predominant item in anuranR. fernandezae, 45 O. americanus and 32 P. albonotatus). Lepidopteran larvae were the predominant item in anuran diets from the soybean field, whereas collembola, isopods and snails prevailed in the diets from forests. Generally, the three anuran species shifted their diets as prey differs in the two environments, but R. fernandezae and P. albonotatus maintainedR. fernandezae and P. albonotatus maintained a preference for a few prey types. Mean niche overlap in the soybean field was smaller than expected by chance, suggesting that the three anuran species are competing for limited resources. Trophic studies on other native anurans in agroecosystems should be a priority in conservation efforts due to their potential use as natural control agents, as well as for assessing the consequences of the broad conversion of natural forest to agricultural use in our region and throughout the world.

Saer con Aira Arce, Rafael Gerardo El trabajo propone un diálogo y una polémica con algunas afirmaciones que sobre la obra de Saer realiza Sandra Contreras en su libro Las vueltas de César Aira. Contreras arma el contexto literario contra el cual emerge la obra de Aira y postula una correlación entre las obras de Saer y de Piglia como los dos nombres ampliamente consensuados que encarnarían los valores literarios vueltos hegemónicos en esa etapa. Nuestro punto de vista intenta discutir esta correlación afirmando que, por el contrario, el consenso crítico en el que descansa es posible gracias a una falta de profundidad en el análisis que permite una generalización y simplificación que se han vuelto, a esta altura, endoxales, significativamente dentro de la misma crítica saeriana. La desconstrucción del binomio tendría como consecuencia, en última instancia, acercar la obra de Saer a la de Aira, de manera tal de desarticular completamente la oposición que establece y que está en el sustrato de la lectura de Contreras.

Ética y política. Reflexiones en torno a la relación entre ética del discurso y democracia deliberativa Prono, Santiago Nicolas

La teoría de la democracia deliberativa, como la ética del discurso, constituye una derivación teórica del enfoque de la racionalidad discursiva. En este sentido este artículo analiza la relación que se plantea entre ambas teorías. Se trata de una tarea pendiente, porque para algunos de los exponentes de esta teoría ética, ella parece asumir el rol de conducir y guiar de un modo exclusivo las decisiones políticas, lo cual implica una reducción de la Filosofía política al campo de la ética.

Preliminares de la traducción: dos antologías de poesía francesa cruzadas Venturini, Santiago Este trabajo realizará un trabajo comparativo entre dos antologías de poesía francesa publicadas en Argentina durante los último 30 años: "Poetas franceses contemporáneos" (1974), compilada por el poeta Raúl Gustavo Aguirre y "Poesía francesa contemporánea" (1997), preparada por el poeta Jorge Fondebrider. El análisis del dispositivo paratextual (prefacios, introducciones, notas) de cada una de estas publicaciones resaltará la intervención determinante del traductor, que construye un marco de lectura y le asigna valores específicos a los textos que traduce.

Thin films of cubic mesoporous aluminophosphates modified by silicon and manganese Cecowski, Sasa; Tusar, Natasa Novak; Rangus, Mojca; Mali, Gregor; Soler Illia, Galo Juan de Avila Arturo; Kaucic, Venceslav Mesoporous aluminophosphate thin films and xerogels with ordered three-dimensional pore arrangement, modified by silicon or silicon and manganese, were synthesized. Aluminophosphate reaction mixtures were templated with non ionic polymer surfactant Pluronic F127 and deposited as thin layers of precursor solution on Petri dishes for xerogels and on glass substrates for thin films. Surfactant removal was investigated by thermal analysis. Small Angle X-ray Scattering measurements showed that calcined silicoaluminophosphate (SAPO) and manganese silicoaluminophosphate (MnSAPO) thin films have highly ordered mesostructures, which remain stable up to at least 400°C. The mesostructures exhibit cubic symmetry described by an Im3̄m space group. Cubic mesostructure was confirmed also by TEM, SEM and AFM microscopy. Incorporation of silicon and manganese into the aluminophosphate framework was studied by solid-state NMR and X-ray absorption spectroscopy. Silicon-rich domains were detected in calcined SAPO and MnSAPO xerogels and in MnSAPO thin films. The observation of Si(OSi)3(OAl) framework units at the border of such domains suggests that acid sites might be included within silicoaluminophosphate walls. Mn3+ and Mn2+ cations are present in the MnSAPO frameworks of calcined xerogels and thin films in the molar ratio of 40%/60%. Manganese cations are coordinated to four oxygen atoms, suggesting that they are incorporated within the framework and that they can act as framework redox sites.