Phase and amplitude measurements for high bandwidth optical signals Bulus Rossini, Laureano Andrés; Costanzo Caso, Pablo Alejandro; Paulucci, Emanuel; Duchowicz, Ricardo; Sicre, Enrique Eduardo In this paper a novel technique for obtaining the amplitude and phase of optical pulses with time extents as short as tens of ps is presented. The method which is based on the transport-of-intensity equation only requires, for a practical realization, of passive fiber optic devices. It employs as the main component a dispersive element with a known second order dispersion coefficient. Two different setup implementations are considered, for which simulations are carried out in order to test the method performance taking into account both, realizable models of the involved devices and typical pulses found in optical transmission systems. The characterization of optical pulses affected by dispersion and nonlinear effects, such as self-phase modulation, is used to evaluate the performance of the method and show the practical feasibility of the future implementation.

Nonlinear Control of a Buck Converter Feeding a Constant Power Load Solsona, Jorge Alberto; Gómez Jorge, Sebastián; Busada, Claudio In this paper a nonlinear control strategy for controlling a dc/dc Buck converter feeding a constant power load is proposed. A feedback controller is combined with a feedforward strategy. A nonlinear reduced order observer is used for estimating the value of the power load and its time derivative. These estimated values are fed forward to the nonlinear feedback controller whose design is based on feedback linearization method. The proposed controller is tested via simulations and also, experimental results are presented.

Measurement of cooling and warming rates in vitrification-based plant cryopreservation protocols Schneider Teixeira, Aline; Gonzalez Benito, M. Elena; Molina García, Antonio D. Cryopreservation protocols include the use of additives and pre-treatments aimed to reduce the probability of ice nucleation at all temperatures, mainly through micro-viscosity increase. Still, there is a risk of ice formation in the temperature region comprised between the equilibrium freezing (Tf) and the glass transition (TG) temperatures. Consequently, fast cooling and warming, especially in this region, is a must to avoid ice-derived damage. Vitrification and droplet-vitrification techniques, frequently used cryopreservation protocols based in fast cooling, were studied, alongside with the corresponding warming procedures. A very fast data acquisition system, able to read very low temperatures, down to that of liquid nitrogen, was employed. Cooling rates, measured between -20 and -120 ºC, ranged from ca. 5 ºC s-1 to 400 ºC s-1, while warming rates spanned from ca. 2 ºC s-1 to 280 ºC s-1, for the different protocols and conditions studied. A wider measuring window (0 ºC to -150 ºC) produced lower rates for all cases. The cooling and warming rates were also related to the survival observed after the different procedures. Those protocols with the faster rates yielded the highest survival percentages.

BMO spaces related to Laguerre semigroups Harboure, Eleonor Ofelia; Chicco Ruiz, Anibal Leonardo For the system of Laguerre functions inline image we define a suitable BMO space from the atomic version of the Hardy space inline image considered by Dziubański in [7], where inline image is the maximal operator of the heat semigroup associated to that Laguerre system. We prove boundedness of inline image over a weighted version of that BMO, and we extend such result to other systems of Laguerre functions, namely inline image and inline image. To do that, we work with a more general family of weighted BMO-like spaces that includes those associated to all of the above mentioned Laguerre systems. In this setting, we prove that the local versions of the Hardy-Littlewood and the heat-diffusion maximal operators turn to be bounded over such family of spaces for inline image weights. This result plays a decisive role in proving the boundedness of Laguerre semigroup maximal operators.

Inverse expression of estrogen receptor alpha and apolipoprotein B in coronary intimal hyperplasia of surgically repaired congenital heart disease: A pre-atherosclerotic condition? Castilla Lozano, Maria del Rocio; Cao, Gabriel Fernando; Kolliker Frers, Rodolfo Alberto; Muller, Angelica del Carmen; Ambrosio, Giuseppe; Milei, Jose Congenital heart diseases (CHD) or the process of their repair leads to an increased risk for adult cardiovascular disease compared with the general population. The proliferation of intimal smooth muscle cells (SMCs), which causes intimal thickenings prior to any evidence of visible lipid deposition, was proposed to be the initial lesion of coronary atherosclerosis. The increasing trend to consider intimal thickenings as possible pre-atherosclerotic lesions is based on the distribution of intimal hyperplasia in children and the localization of characteristic atherosclerotic lesions observed in adult humans. Early coronary artery lesions may range from focal areas with mild myointimal thickenings in prenatal life to early soft plaques in infants, which may also present as intermingled lesions with components of both categories, more frequently observed with increasing age. Also,we proposed that TGF-β1 expressionmight be considered another possible predisposing factor to develop atherosclerotic coronary artery disease in CHD patients. On the other hand, estrogen receptor-α (ERα) appears to be responsible for the protective effects of estrogens against atherosclerotic vascular disease. The aim of this paper was to analyze the immunohistochemical expression of ERα, TGF-β1 and apolipoprotein B in coronary intimal hyperplasia in children with CHD and the possible increased risk for the development pre-atherosclerotic lesions.

Numerical integration of the stochastic Landau-Lifshitz-Gilbert equation in generic time-discretization schemes Romá, Federico José; Cugliandolo, Leticia F.; Lozano, Gustavo Sergio We introduce a numerical method to integrate the stochastic Landau-Lifshitz-Gilbert equation in spherical coordinates for generic discretization schemes. This method conserves the magnetization modulus and ensures the approach to equilibrium under the expected conditions. We test the algorithm on a benchmark problem: the dynamics of a uniformly magnetized ellipsoid. We investigate the influence of various parameters, and in particular, we analyze the efficiency of the numerical integration, in terms of the number of steps needed to reach a chosen long-time with a given accuracy.

Carma Large Area Star Formation Survey: observational analysis of filaments in the serpens south molecular cloud Fernandez Lopez, Manuel; Arce, H. G.; Looney, Leslie W.; Mundy, Lee G.; Storm, S.; Teuben, P. J. ; Lee, K.; Segura Cox, Dominique M.; Isella, A.; Tobin, John J.; Rosolowsky, E.; Plunkett, A. ; Kwon, Woojin; Kauffmann, J.; Ostriker, E. ; Tassis, K.; Shirley, Y. L.; Pound, M. We present the N2H+ (J = 1 → 0) map of the Serpens South molecular cloud obtained as part of the CARMA Large Area Star Formation Survey. The observations cover 250 arcmin2 and fully sample structures from 3000 AU to 3 pc with a velocity resolution of 0.16 km s−1, and they can be used to constrain the origin and evolution of molecular cloud filaments. The spatial distribution of the N2H+ emission is characterized by long filaments that resemble those observed in the dust continuum emission by Herschel. However, the gas filaments are typically narrower such that, in some cases, two or three quasi-parallel N2H+ filaments comprise a single observed dust continuum filament. The difference between the dust and gas filament widths casts doubt on Herschel ability to resolve the Serpens South filaments. Some molecular filaments show velocity gradients along their major axis, and two are characterized by a steep velocity gradient in the direction perpendicular to the filament axis. The observed velocity gradient along one of these filaments was previously postulated as evidence for mass infall toward the central cluster, but these kind of gradients can be interpreted as projection of large-scale turbulence.

Pliocene Orographic Barrier Uplift in the Southern Central Andes Pingel, Heiko; Alonso, Ricardo Narciso; Mulch, Andreas; Rohrmann, Alexander; Sudo, Masafumi; Strecker, R. Sedimentary basin fills along the windward flanks of orogenic plateaus are valuable archives of paleoenvironmental change with the potential to resolve the history of surface uplift and orographic barrier formation. The intermontane basins of the southern Central Andes contain thick successions of sedimentary material that are commonly interbedded with datable volcanic ashes. We relate variations in the hydrogen isotopic composition of hydrated volcanic glass (δDg) of Neogene to Quaternary fills in the semiarid intermontane Humahuaca Basin (Eastern Cordillera, northwest Argentina) to spatiotemporal changes in topography and associated orographic effects. δD values from volcanic glass in the basin strata (–117‰ to –98‰) show two main trends that accompany observed tectonosedimentary events in the study area. Between 6.0 and 3.5 Ma, δDg values decrease by ∼17‰; this is associated with surface uplift in the catchment area. After 3.5 Ma, δDg values show abrupt deuterium enrichment, which we associate with (1) the attainment of threshold elevations for blocking moisture transport in the basin-bounding ranges to the east, and (2) the onset of semiarid conditions in the basin. Such orographic barriers throughout the eastern flanks of the Central Andes have impeded moisture transport into the orogen interior; this has likely helped maintain aridity and internal drainage conditions on the adjacent Andean Plateau.

A multilocus perspective on the phylogenetic relationships and diversification of rodents of the tribe Abrotrichini (Cricetidae: Sigmodontinae) Cañón Valenzuela, Carola Patricia; Mir, Daiana; Pardiñas, Ulises Francisco J.; Lessa, Enrique P.; D´Elía, Guillermo Abrotrichini is a recently defined and diagnosed tribe of Sigmodontinae with a complex taxonomy. Abrotrichine genera, Abrothrix (including Chroeomys), Chelemys, Geoxus, Notiomys and Pearsonomys, are mostly distributed in the central and southern Andes and adjacent lowlands and show terrestrial and fossorial habits. Recent studies have evidenced some incongruence between current taxonomy and abrotrichine phylogeny, such as the polyphyly of Chelemys and paraphyly of Geoxus respect to Pearsonomys. We used DNA sequence data of six loci (one mitochondrial and five nuclear) to resolve the relationships within the tribe. Independent and combined analyses of these loci were carried out using parsimony, maximum likelihood and Bayesian inference. Estimates of divergence time of the main lineages of abrotrichines were calculated with a molecular clock using as calibration, a fossil recently found. The concatenated data set increased the resolution and defined the relationships within the tribe. Our phylogenetic analyses corroborate that Abrothrix is sister of a clade containing the long-clawed abrotrichines. We recovered two main clades within Abrothrix that match morphologic variation and geographic distribution of its species. In addition, we corroborated the lack of monophyly of Chelemys and the lack of monophyly of Geoxus. We discuss different taxonomic scenarios to abrotrichine classification reflects the phylogenetic relationships obtained in this study. Our molecular clock estimated the Abrotrichini crown age to be around the early Pliocene (4.4 Ma) and suggest that the tribe diversified over a short period of time.

Microfungal composition in an Astellia-Donatia cushion peatland in Tierra del Fuego, Argentina Paredes, Noelia Ivana; Consolo, Verónica Fabiana; Pancotto, Veronica Andrea; Fritz, Christian; Barrera, Marcelo Daniel; Arambarri, Angélica Margarita; Salerno, Graciela Lidia Southern Hemisphere peatlands store substantial amounts of soil carbon. Despite their importance in the global carbon cycle, little is known about decomposition processes and the associated fungal diversity. The present study describes the composition of fungal assemblage in two depths from a cushion peatland of predominating Astelia (Asteliaceae) and Donatia (Donatiaceae) species in Moat, Tierra del Fuego. From 48 samples processed, we obtained 338 isolates. Using different culturing methodologies, through direct and microscopic observation and using molecular methods we identified 38 fungal species and 18 genera of Ascomycetes and Zygomycetes. Isolates belonging to Ascomycetes were the most abundant, with dominance of Penicillium and Trichoderma. We described fungal composition and compared species diversity and evenness across two dephts. No differences in the diversity index and evenness were found between depths. The studied peat is an ecosystem that has a great diversity of filamentous fungal species, some of which are described in other peatlands worldwide.

Interannual variations in primary and secondary growth of Nothofagus pumilio and their relationships with climate Magnin, Noel Amaru; Puntieri, Javier Guido; Villalba, Ricardo The relationships between apical (or primary) and radial (or secondary) growth, and climatic influences on both types of growth, were evaluated for Nothofagus pumilio (Nothofagaceae), the dominant subalpine tree in Patagonia. We measured the spacing and number of nodes of annual shoots developed in the period 2001-2010 in 40 N. pumilio trees growing near the upper treeline in the northern Patagonian Andes (41ºS). Variations in ring width at the base of each trunk were also recorded. Interannual variations in primary and secondary growth were significantly related to each other, and to several climate variables. Mean temperatures in winter and early spring (June to October) prior to the period of shoot extension were positively associated with both primary and secondary growth. In addition, total summer precipitation (December to March) was positively related to shoot extension, whereas mean summer temperature during the previous growth season (January to March) was directly related to radial growth. These climatic influences on N. pumilio growth may play a major role in regulating the expressions of preformation and neoformation.

Plant functional traits and phylogenetic relatedness explain variation in associations with root fungal endophytes in an extreme arid environment Lugo, Mónica Alejandra; Reinhart, Kurt O.; Menoyo, Eugenia; Crespo, Esteban María; Urcelay, Roberto Carlos Since root endophytes may ameliorate drought stress, understanding which plants associate with endophytes is important, especially in arid ecosystems. Here, the root endophytes were characterized of 42 plants from an arid region of Argentina. Colonization by arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSEs) was related to plant functional type (PFT), family, and phylogenetic relatedness. Overall, three main findings were observed. Firstly, only moderate levels of endophyte associations were found across all taxa (e.g., most Poaceae were not colonized by endophytes despite numerous accounts of colonization by AMF and DSEs). We determined 69 % of plant taxa associated with some form of root endophyte but levels were lower than other regional studies. Secondly, comparisons by PFT and phylogeny were often qualitatively similar (e.g., succulents and Portulacineae consistently lacked AMF; variation occurred among terrestrial vs. epiphytic bromeliads) and often differed from comparisons based on plant family. Thirdly, comparisons by plant family often failed to account for important variation either within families (e.g., Bromeliaceae and Poaceae) or trait conservatism among related families (i.e., Rosidae consistently lacked DSEs and Portulacineae lacked AMF). This study indicates the value of comparing numerous taxa based on PFTs and phylogenetic similarity. Overall, the results suggest an uncertain benefit of endophytes in extremely arid environments where plant traits like succulence may obviate the need to establish associations.

The Future of Philosophy of History from its Narrativist Past: Figuration, Middle Voice Writing and Performativity la Greca, María Inés Hayden White inaugurated narrativism in philosophy of history when he effected a productive displacement of earlier epistemological discussions around the relationship between narration and historical knowledge: White identified the problem of narrative in history with the problem of the use of figurative language in the representation of the past. Thus, he enabled a new way of thinking philosophy of history’s object of study by paying attention to an aspect of historical practice he considered wrongly overlooked: the writing of history. His formal theory of the historical work needs no introduction. Instead, this paper aims at reclaiming the fundamental philosophical legacy White has left us in his latest work on middle voice writing.  First, I will frame White’s thought as a response to what I call the paradoxical nature of historical narrative, as Louis Mink and Roland Barthes understand it. By presenting our narrativist past as White’s ironical and liberating stance on historical narrative, I will show how he identified figuration as the paradoxical resource and constrain of historical writing. Secondly, I will elaborate on his latest inquiries into middle voice writing as pointing the way into the future of philosophy of history. Thus, I will claim that the notion of middle voice writing that White adopted from Roland Barthes should be read from the point of view of performativity theory in order to reassess the philosophical nature of historical writing now considered as the performative self-constitution of the historical subject.

El pasajero oscuro. Elucubraciones sobre Dexter; The dark passenger. Musings about Dexter Murolo, Norberto Leonardo El trabajo propone tópicos de reflexión sobre la serie televisiva Dexter, emitida por el canal Showtime. Como narración proveniente de la industria cultural estadounidense su éxito llevó a que se difundiera en todo el mundo y que sus fans se multiplicaran. La serie tematiza la historia de un asesino serial diferente a los del cine hollywoodense. Dexter no quiere ser quien es y lucha contra una parte de él mismo que tiene como impulso matar; como él lo llama: su pasajero oscuro. En medio de esa historia se entrecruzan múltiples temas que tocan a la condición humana. El mal y el bien, la justicia y la injusticia, los héroes y los antihéroes son cuestiones constantes en la serie. Asimismo, las relaciones familiares, sobre todo entre el personaje protagónico y su hermana, son centrales a la hora de decodificar este discurso que, gracias a las tecnologías digitales, cuenta con adeptos de todo el mundo.; This paper proposes topics of reflection on the Showtime television series, Dexter. As a narrative from the American cultural industry, success led it to spread throughout the world, multiplying its fans. The series is about a serial murderer with a different story than the Hollywood ones. Dexter doesn’t want to be who he is and fights against a part of him that has killing as an impulse –his “dark passenger”, as he calls it-. As the story unfolds, multiple threads related to the human condition intersect. The good and evil, justice and injustice, heroes and antiheroes are regular issues in the series. Also, family relationships, especially between the main character and her sister, are essential while decoding this speech that, thanks to digital technologies, has followers all over the world.

¿Cómo pensar el afecto en la política? Aproximaciones y debates en torno a la teoría de la hegemonía de Ernesto Laclau Blanco, Ana Belén; Sánchez, María Soledad Este artículo se propone aprehender la forma en la que la dimensión del afecto es problematizada en la teoría de la hegemonía de Laclau, a partir de una reconstrucción de sus principales conceptos teóricos así como de los debates intelectuales que se han suscitado al respecto. Presentaremos un recorrido transversal por las producciones del autor a fin de reconstruir sucintamente los elementos fundamentales que componen su teoría. Posteriormente, profundizaremos sobre la incorporación de la dimensión afectiva como un componente primario de todo proceso de construcción hegemónica, explicitando la imposibilidad de reducir esta última a operaciones estrictamente lingüísticas. Abordar el vínculo entre hegemonía y economía afectiva permite revalorizar el aporte teórico de Laclau al identificar las herramientas heurísticas que este brinda para el análisis sociopolítico.

Diseño Instructivo e Inteligencias Múltiples. Percepciones de los alumnos Rigo, Daiana Yamila; Donolo, Danilo Silvio La investigación que se presenta tiene como objetivo diseñar e implementar un diseño instructivo orientado en la teoría de las inteligencias múltiples (IM-TIM) o modelo de entry points de Gardner y evaluar la propuesta a partir de la percepción de los estudiantes sobre los puntos fuertes y débiles del modelo. El estudio es conducido en educación primaria con alumnos de 6to grado en el área de Ciencias Sociales. En total, se trabajó con 14 alumnos y la docente de grado. Para la recolección de datos se utilizaron entrevistas semi-estructuradas. Los resultados indican que la propuesta educativa fundamentada en las IM contribuye a: un mayor interés sobre las tareas académicas, la promoción del aprendizaje, al acceso al conocimiento y su transferencia, la colaboración en la construcción del conocimiento y una mayor consideración de la importancia de contextualizar las tareas para aprender en profundidad.

Local maximal functions and operators associated to Laguerre expansions Viola, Pablo Sebastian; Viviani, Beatriz Eleonora In this paper we get sharp conditions on a weight v which allow us to obtain some weighted inequalities for a local Hardy-Littlewood Maximal operator defined on an open set in the Euclidean n-space. This result is applied to assure a pointwise convergence of the Laguerre heat-diffusion semigroup u(x,t) = (T(t)f)(x) to f when t tends to zero for all functions f in L p(v(x)dx) for p greater than or equal to 1 and a weight v. In proving this we obtain weighted inequalities for the maximal operator associated to the Laguerre diffusion semigroup of the Laguerre differential operator of order greater than or equal to 0. Finally, as a by-product, we obtain weighted inequalities for the Riesz-Laguerre operators.

Parental expectations and prosocial behavior of adolescents from low-income backgrounds. A cross-cultural comparison between three countries: Argentina, Colombia and Spain Mesurado, Maria Belen; Richaud, Maria Cristina; Mestre, María Vicenta; Samper García, Paula; Tur Porcada, Ana; Morales Mesa, Santiago Alberto; Viveros, Francisco Edison Parental expectations are influenced by cultural models, which in turn are subject to a great influence from historically fluctuating features of the socioeconomic background. Parental expectations seem to be linked to children’s social and emotional development in terms of empathy and prosocial behavior. The current study aims to (a) compare low-income adolescents’ perceptions of parental expectations of prosocial and antisocial behavior across three Latin countries (Argentina, Colombia, and Spain), (b) compare the empathy and prosocial behavior between the three countries, (c) compare the prosocial behavior between the three countries, and (d) study the effect of perceived parental expectations and empathy on the prosocial behavior of adolescents in all three of the countries studied in this research. The sample was made up of 446 Argentinean adolescents, 474 Colombian adolescents, and 632 Spanish adolescents. The Expected Parental Reactions Scale, Interpersonal Reactivity Index, and Prosocial Behavior Questionnaire were used to measure the variables included in this study. Results reveal considerable differences between children’s perceptions of parental expectations in different countries. Results also show the existence of significant differences between male and female adolescents. In all three countries, girls score more highly than boys in prosocial behavior and empathy. Furthermore, we find that low-income Argentinean adolescents score more highly than Spanish and Colombian adolescents in prosocial behavior measures. Finally, expected parental reactions toward prosocial behavior and empathy seem to have an influence on the adolescents’ development of prosocial behavior in all three countries.

RDG System in Remote Areas with Utility or Local Feed Topology and Operation Strategy Toccaceli, Graciela Mabel; Peña, Ricardo Ramiro; Cendoya, Marcelo Gustavo; Battaiotto, Pedro Eduardo In remote regions with availability of wind energy, a RDG (renewable distributed generation) system is an advantageous alternative to increase the provision of electrical supply. Usually, these systems are structured on the basis of a connection to an existing weak grid. When the grid is out of service, the system may operate in islanding mode, if the RDG configuration allows it, continuing the provision of energy with standard voltage and frequency values. Facing the latter situation, a wind-diesel/gas generation system is proposed, with a conversion and control strategies based on a variable speed wind turbine employing a DFIG (doubly fed induction generator), a SC (ultracapacitor) storage system and a SG (synchronous generator) driven by a diesel/gas engine.

La lógica originaria y el lenguaje de las señas Walton, Roberto Juan En su curso sobre Heráclito de 1944, Heidegger caracteriza nuestra relación con el ser de este modo: ?Pero esta relación pensante y que se ha de pensar es el pensar mismo, que, en una lógica originaria, viene a estar en la propia claridad, que, sin embargo, no es su claridad que ha hecho por sí misma? (GA 55, p. 372). Puesto que consiste en el simple dejar esenciarse o desplegarse el ser desde su propia verdad, esta lógica carece de un contenido doctrinario. Un modo de caracterizarla es por medio de los peligros que acechan al pensar: El peligro bueno (gute) y por eso saludable es la vecindad del poeta que canta. El peligro nocivo (böse) y por eso más agudo es el pensar mismo. Él debe pensar contra sí mismo, lo que solo es capaz de hacer raramente. El peligro malo (schlechte) y por eso confuso es el filosofar (GA 13, p. 80). En el primer apartado del trabajo se considera cómo el pensar mismo pierde su carácter originario mediante la sustitución de la lógica originaria y el lenguaje de las señas por la lógica del enunciado y el lenguaje de los signos. En el siguiente apartado se examina, mediante una consideración de las señas del Ser, el peligro representado por el filosofar. El tercer apartado se ocupa del restante peligro que surge de querer extraer un pensar del poetizar. Finalmente, se analiza la relación de la lógica originaria con la hermenéutica y la fenomenología. Por un lado, Heidegger trata de pensar más originariamente el esenciar de la fenomenología a fin de retroensamblarla de esta manera a propósito en su pertenencia a la filosofía occidental (GA 12, p. 91). Por el otro, al caracterizar la relación con el ser como ?la relación hermenéutica, recurre al sentido originario de hermeneúein, que no concierne a la (268) metodología de la interpretación, ?porque lo hermenéutico no significa en primer lugar el interpretar sino ante todo el traer mensaje y noticia? (GA 12, p. 115).