A comparative study of invasive Helianthus annuus populations in their natural habitats of Argentina and Spain; Poblaciones invasoras de Helianthus annuus en Argentina y España; Populations envahisseurs de Helianthus annuus en Argentine et en Espagne Poverene, María Mónica; Cantamutto, Miguel Ángel Wild Helianthus annuus is native to North America but it naturalized in other parts of the world as well. Although the origin of exotic populations is uncertain, they have probably evolved very differently in different countries. To unravel the origin of invasive populations from Argentina and Spain, morphological and agro-ecological data of nine populations from central Argentina, six from Andalusia and one from Gerona were collected in their natural habitats during three exploration trips in 2007 and 2008. In Argentina wild H. annuus was found mainly in disturbed areas between roads and fences. In a few cases the populations were located on the margins of cultivated fields. The Argentinean populations are spread across more than 50,000 m2 at a density of about 25 plants m-2. In Spain, the populations were found mainly in croplands. The largest population covered about 1,500 m2 and comprised no more than 200 plants. The Argentinean populations had taller plants with a higher number of heads of small size, while the Spanish populations were characterized by bigger heads with wider ligules and bracts. Plants were shorter and leaf size was larger in Gerona than in Andalusia. Multivariate analysis differentiated populations from Argentina and Spain by many traits. Wild-crop gene flow is likely the source of genetic variation among them. In Argentina, the populations keep the appearance of early wild introductions, while the Spanish populations are weedier and probably originated from pollen contamination of commercial seed with wild plants or crop-wild hybrids.

Testing detection and discrimination of vegetation chemical cues in the subterranean rodent Ctenomys talarum Schleich, Cristian; Zenuto, Roxana Rita Previous studies on the subterranean rodent Ctenomys talarum (tuco-tuco) have shown that this species has the ability to use olfaction to orient their digging while foraging. As a continuation of these works, we assess whether direct contact with vegetation chemical signals is required for food odour recognition, and whether this subterranean rodent is also able to discriminate plants of different nutritional quality by the chemical signals released by them into the soil. First, we test animal responses to plant extracts and controls (water) covered with a wire mesh or without it. Also, we assess individual digging response in an artificial Y-maze whose arms were filled with soil in which plants of different nutritional quality have been grown. The results of this study suggest that (i) volatile chemical cues allow food odour recognition and direct contact with the odour source does not enhance such recognition in C. talarum, and (ii) olfaction could play a key role in the finding of food patches, allowing individuals to direct their excavation towards plant species of high nutritional quality. © 2010 Dipartimento di Biologia Evoluzionistica dell'Universitá, Firenze, Italia.

Identification of the long polar fimbriae gene variants in the locus of enterocyte effacement-negative Shiga toxin-producing Escherichia coli strains isolated from humans and cattle in Argentina Galli, Lucía; Torres, Alfredo G.; Rivas, Marta The long polar fimbriae (Lpf) is one of few adhesive factors of Shiga toxin-producing Escherichia coli (STEC) and it is associated with colonization of the intestine. Studies have demonstrated the presence of lpf genes in several pathogenic E. coli strains, and classification of variants based on polymorphisms in the lpfA1 and lpfA2 genes has been adopted. Using a collection of Argentinean locus of enterocyte effacement (LEE)-negative STEC strains, we determined that the different lpfA types were present in a wide variety of serotypes with no apparent association between the types of lpfA1 or lpfA2 genes and the severity of human disease. The lpfA2-1 was the most prevalent variant identified, which was present in 95.8% of the isolates, and lpfA1-3 and lpfA2-2, proposed as specific biomarkers of E. coli O157:H7, were not found in any of the serotypes studied. The prevalence of lpf genes in a large number of strains is useful to understand the genetic diversity of LEE-negative STEC and to define the association of some of these isolates carrying specific lpf-variants with disease.

Morphofunctional patterns in Neotropical felids: Species co-existence and historical assembly Morales, Miriam Mariana; Giannini, Norberto Pedro Extant felids are morphologically homogeneous, probably as a result of recent radiation and constraints from their predatory specializations. The Neotropical assemblage comprises 12 of the 41 extant felid species, which occupy all habitats available, with many species coexisting locally. We studied this assemblage on the basis of 31 craniodental variables reflecting morphofunctional variation, measured from 229 specimens representing all 12 species. Multivariate patterns were summarized allowing for phylogenetic covariation. Additional factors (geographical distribution, use of habitat and stratum, and activity pattern) were coded for each species. As expected, body size accounted for most variation, covarying with membership to three deep clades and, to a lesser extent, with large-scale geographic variation. The species tend to segregate in morphospace plus one or more factors (e.g. habits) that make interspecific overlap in niche space minimal. Using dated phylogenies, biogeographic history, and the fossil record, we reconstructed the historical assembly of the Neotropical felid guild. We found a pattern of successive invasions and speciation in which new lineages occupied previously vacant areas of morphospace, or new species occupied overlapping areas but with contrasting habits. This may be general among antagonistic species of historically structured guilds, and we predict similar patterns in other continents.

Surface plasmon resonance aided electrochemical immunosensor for CK-MB determination in undiluted serum samples Garay, Fernando Sebastian; Kisiel, Greggory; Fang, Aiping; Lindner, Erno This article presents a simple chronoamperometric immunosensor for the quantitative assessment of creatine kinase MB (CK-MB) in 50 μL undiluted serum samples. The immunosensor consists of gold working and counter electrodes patterned onto a glass chip by thin-film photolithography and an external Ag|AgCl reference electrode. The detection limit (DL) of the chronoamperometric method is 13 ng mL-1 (DL = 2×RMSD/S, where RMSD is the residual mean standard deviation of the measured points around a calibration curve with a slope of S). In spiked serum samples, the response was linear up to 300 ng mL-1 of CK-MB. A surface plasmon resonance (SPR) system with simultaneous electrochemical detection (EC-SPR) aided the development of the sandwich immunoassay. Real-time monitoring of the SPR signal was used to optimize the capture antibody immobilization, CK-MB and detection antibody binding, as well as to minimize the nonspecific adsorption of serum proteins to the sensor surface. The detection antibody has been labeled with alkaline phosphatase (ALP) enzyme for sensitive electrochemical detection. ALP catalyzes the hydrolysis of ascorbic acid phosphate and generates ascorbic acid, which is measured chronoamperometrically. The electrochemical immunoassay for CK-MB was less sensitive to nonspecific adsorption related interferences, had a better detection limit, and required a lower volume of sample than the SPR method. © 2010 Springer-Verlag.

Effects of the inclusion of bending-to-stretching transitions in the non-LTE modeling of ozone vibrational temperatures Fernandez, Rafael Pedro; Kaufmann, Martín; Toselli, Beatriz Margarita A description of the non-LTE intramolecular ozone relaxation cascade considering the relative importance of different transitions on the O3(v1v2v3) vibrational levels has been studied by quantifying the kinetic law of every process and transition that affect each level population. The analysis considers the inclusion for the first-time of bending-to-stretching (k2D) transitions in the energy relaxation cascade of ozone after it is formed by three-body recombination. In this way, the vibrational temperatures and the relative contribution of every transition are presented as a function of altitude. The results show that the inclusion of the bending-to-stretching transitions in the O3 non-LTE relaxation scheme decreases the ν2-mode overpopulation and therefore the stretching levels' population increases, as required for a correct radiance simulation of the 4.8γm ozone emission in the upper atmosphere.

Design and synthesis of active vitamin D analogs Eduardo, Silvina Laura; Fraga, Ramón; Sigüeiro, Rita; Marco, Maria; Rochel, Natacha; Moras, Dino; Mouriño, Antonio A review of the design and synthesis of structural analogs of the vitamin D hormone recently investigated in our laboratories, and the first report on a new class of vitamin D analogs characterized by an aromatic D-ring, is described.

Direct and correlated responses to artificial selection for high and low knockdown resistance to high temperature in Drosophila buzzatii Sambucetti, Pablo Daniel; Scannapieco, Alejandra Carla; Norry, Fabian Marcelo Knockdown resistance to high temperature (KRHT) is a genetically variable trait for thermal adaptation in insects. Selection for KRHT may affect a number of fitness components as well as resistance to several forms of environmental stress. To test for heritable (co)-variation in KRHT, we examined direct and correlated responses to bi-directional selection on this trait in Drosophila buzzatii. Replicated lines were artificially selected for decreased and increased KRHT. After 12 generations of artificial selection, lines diverged significantly for high KRHT only. Starvation resistance increased in two lines that strongly responded to selection for high KRHT, and these two lines also showed relatively longer chill-coma recovery time. Developmental time and body size showed no correlated responses to KRHT-selection. These results suggest that KRHT is a heritable trait that can evolve towards increased thermotolerance with no genetic trade-offs associated to starvation resistance, developmental time and body size.

Eficiencia agronómica del azufre elemental relativa a una fuente azufrada soluble en trigo en la región pampeana; Agronomic efficiency of elemental sulphur in wheat relative to a soluble sulphur source in the Pampas Region Torres Duggan, Martin; Rodríguez, Monica B.; Lavado, Raul Silvio; Melgar, Ricardo La eficiencia agronómica del azufre elemental (AE) en relación a fuentes azufradas solubles y sulfatadas, depende de su reactividad (e.g. tamaño de partícula) y de las condiciones edafo-climáticas. Para las condiciones de la Región Pampeana algunas publicaciones sugieren que el AE puede ser una fuente de S tan efectiva como las fuentes solubles, aunque la información no concluyente. Se hipotetiza que en las condiciones de la Región Pampeana, ambas fuentes poseen similar eficiencia agronómica en la mayoría de los años. Los objetivos del trabajo fueron: i. Evaluar la respuesta al agregado de S con una fuente reactiva de AE en relación a un fertilizante azufrado sulfatado, aplicado en trigo en diferentes dosis y en distintas condiciones edafo-climáticas; ii. Comparar, para el conjunto de experimentos, la eficiencia agronómica del S aplicado con las distintas fuentes. iii. Relacionar las respuestas a la fertilización azufrada con variables de suelo y clima. Se realizaron ocho ensayos de campo durante dos años consecutivos en lotes de producción ubicados en la Región Pampeana. Se aplicó un diseño en bloques completos aleatorizados con cuatro o seis repeticiones en un arreglo factorial de tratamientos (factor 1: fuente azufrada, factor 2: dosis de S). Los tratamientos fueron: un testigo absoluto; fertilización con AE micronizado (95% de S) en dos niveles de dosis y fertilización con sulfato de amonio granulado (SA, 24% S), también en dos niveles de dosis. Las dosis evaluadas fueron 10 y 30 kg ha-1 de S (año 1) y 15 y 30 kg ha1 (año 2). La fertilización azufrada afectó significativamente (p<0,05) los rendimientos del trigo en cuatro de cinco sitios en el primer año y en todos los sitios durante el segundo año de experimentos. Las respuestas del trigo al S se ubicaron en el rango de 231 a 857 kg ha-1 en el primer año y entre 702 y 2.119 kg ha-1 en el segundo año. No se observaron efectos significativos de fuente (efectividad) en las respuestas observadas o en la eficiencia agronómica del S aplicado (kg de grano kg de S aplicado en la mayoría de los sitios), confirmándose que, para el conjunto de experimentos, ambos fertilizantes fueron igualmente efectivos para proveer SO 2-al cultivo. Tampoco se detectó efecto significativo de dosis o interacción fuente x dosis (p>0,05) en la mayoría de los sitios. La dosis más baja (10 o 15 kg ha-1) fue suficiente para cubrir el requerimiento de S del cultivo. Se observó una asociación positiva entre las respuestas y el contenido de MO del suelo y las precipitaciones (macollaje y total del ciclo) y una relación inversa con el contenido de S-SO42- disponibles a la siembra, ésta última con bajo ajuste (r2 medio=0,18). No se observó asociación entre las respuestas y la temperatura en macollaje o en el ciclo. Se concluye que el AE resultó una fuente azufrada con similar eficiencia que el SA para aportar S al trigo en la Región Pampeana.; Agronomic efficiency of elemental sulphur (AE) compared with soluble and S-sulphate sulphur sources depends on reactivity of AE (e.g. particle size) and environmental conditions (soil and climate). Although there is published information suggesting that elemental sulphur has similar effectiveness than soluble sulphur sources, the information is not conclusive. We hypothesized that agronomic efficiency of AE and soluble S sources are similar under the Pampas Region conditions. The objectives of the study were to: i. Evaluate S grain response to a reactive source of AE compared to a soluble S source under different S rates and soil and climate conditions. ii. Compare, for the group of experiments, agronomic S efficiency between S sources. iii: Relate S responses with soil and climatic variables. Eight field experiments were conducted during two successive years on cropping systems in the Pampas Region. The experimental design was a randomized complete block with four or six replicates and a factorial treatment arrangement (factor 1: S source, factor 2: S rate). The treatments were: check (without S application), fertilization with a micronized source of AE (95% of S) and a fertilization treatment with ammonium sulphate (SA, 24%). Both sulphur sources were applied at two S rates. Sulphur rates were 10 and 30 kg ha1 (year 1) and 15 and 30 kg ha-1 (year 2). In the first year, wheat responded significantly to S in four of five sites (p<0.05) with yield increases of 231 to 857 kg ha-1. Significant yield increases were observed in all sites in the second year, ranging from 702 to 2,119 kg ha-1. There were no significant differences in grain yield among S sources, rates or interaction source x S rates (p>0.05) in most sites. When all sites were combined, sulphur sources presented similar agronomic S efficiencies (p>0.05). The lower S rate (10 or 15 kg ha1) was enough to provide S to the crop under the Pampas Region conditions. Grain yield responses to S were positively correlated with organic matter content and rainfall (during tillering or the whole crop cycle) and inversely associated with SO42- at planting, although with a poor adjustment. No correlation was detected between S response and temperatures during tillering or the whole crop cycle.

Garlic powder and wheat bran as fillers: Their effect on the physicochemical properties of edible biocomposites Fama, Lucia Mercedes; Bittante, Ana Mônica B. Q.; Sobral, Paulo J. A.; Goyanes, Silvia Nair; Gerschenson, Lia Noemi Biocomposites with two different fillers, garlic and wheat bran, were studied. They were based on cassava starch and contained glycerol as a plasticizer and potassium sorbate as an antimicrobial agent and were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and infrared spectroscopy (IR). The mechanical performance at room and lower temperatures was also studied. SEM micrographies of fractured surfaces of the wheat bran composite films showed some ruptured particles of fiber while fibrils of garlic on the order of nanometers were observed when garlic composite films were studied. Mechanical tests, at room temperature, showed that the addition of wheat bran led to an increment in the storage modulus (E′) and hardening and a decrease in Tan δ, while the garlic composite showed a diminishing in the E′ and hardening and did not produce significant changes in Tan δ values when compared with systems without fillers (matrix). In the range between -90 °C and 20 °C, all the materials studied presented two peaks in the Tan δ curve. In the case of the wheat bran composite, both relaxation peaks shifted slightly to higher temperatures, broadened and diminished their intensity when compared with those of the matrix; however garlic composite showed a similar behavior to the matrix. DSC thermograms of aqueous systems showed a slight shift of gelatinization temperature (Tgelatinization) to higher values when the fillers were present. Thermograms of films showed that both, garlic and wheat bran composites, had a lower melting point than the matrix. IR data indicated that interaction between starch and fillers determined an increase in the availability of hydroxyl groups to be involved in a dynamic exchange with water.

Von Willebrand's disease diagnosis and laboratory issues Castaman, G.; Montgomery, R. R.; Meschengieser, S. S.; Haberichter, S. L.; Woods, Adriana Inés; Lazzari, María Ángela In this paper, the recent developments in the diagnosis and laboratory issues of von Willebrand's disease (VWD) are presented. Dr. Castaman reviews the functional tests available for the diagnosis of VWD and their pathophysiological significance, focusing on which tests are best used in the diagnosis and classification of VWD. Dr Montgomery reviews an emerging issue that is accelerated clearance of von Willebrand factor (VWF) occurring in some variants of VWD. This phenotype can be suspected by the presence of an increased ratio between the VWF propeptide and the VWF antigen. These patients have typically a robust, but short-lived increase of FVIII and VWF after desmopressin. Dr Meschengieser reviews the determinants of bleeding after surgery in patients with VWD, emphasizing the role of bleeding history in predicting this risk. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Ltd.

The INGV–CMCC Seasonal Prediction System: Improved Ocean Initial Conditions Alessandri, Andrea; Borrelli, Andrea; Masina, Simona; Cherchi, Annalisa; Gualdi, Silvio; Navarra, Antonio; Di Pietro, Pierluigi; Carril, Andrea Fabiana The development of the Istituto Nazionale di Geofisica e Vulcanologia (INGV)–Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC) Seasonal Prediction System (SPS) is documented. In this SPS the ocean initial-conditions estimation includes a reduced-order optimal interpolation procedure for the assimilation of temperature and salinity profiles at the global scale. Nine-member ensemble forecasts have been produced for the period 1991–2003 for two starting dates per year in order to assess the impact of the subsurface assimilation in the ocean for initialization. Comparing the results with control simulations (i.e., without assimilation of subsurface profiles during ocean initialization), it is shown that the improved ocean initialization increases the skill in the prediction of tropical Pacific sea surface temperatures of the system for boreal winter forecasts. Considering the forecast of the 1997/98 El Nin˜o, the data assimilation in the ocean initial conditions leads to a considerable improvement in the representation of its onset and development. The results presented in this paper indicate a better prediction of global-scale surface climate anomalies for the forecasts started in November, probably because of the improvement in the tropical Pacific. For boreal winter, significant increases in the capability of the system to discriminate above-normal and below-normal temperature anomalies are shown in both the tropics and extratropics.

On sign conditions over real multivariate polynomials Jeronimo, Gabriela Tali; Perrucci, Daniel Roberto; Sabia, Juan Vicente Rafael We present a new probabilistic algorithm to find a finite set of points intersecting the closure of each connected component of the realization of every sign condition over a family of real polynomials defining regular hypersurfaces that intersect transversally. This enables us to show a probabilistic procedure to list all feasible sign conditions over the polynomials. In addition, we extend these results to the case of closed sign conditions over an arbitrary family of real multivariate polynomials. The complexity bounds for these procedures improve the known ones.

Las principales reformas de la relación salarial operadas durante el período 2002-2009 Berasueta, Ana Cecilia; Biafore, Eugenio; Neffa, Julio Cesar; Wahlerb, Verónica Laura El tema de los cambios en las instituciones y en las normas de derecho del trabajo y de la seguridad social a lo largo del tiempo da lugar a muchos estudios y controversias, dada la tendencia a evolucionar en diversos sentidos. En un primer documento (Neffa, Biafore, Cardelli y Gioia, 2005) la atención del equipo de investigación se centró en el relevamiento de las reformas laborales que se introdujeron durante el régimen de la convertibilidad (periodo 1989-2001) confrontándolo con la situación precedente. De allí surgió la evidencia de que a pesar de que se considera que en ese periodo la política económica tuvo como objetivo la desregulación, sucedió lo contrario en materia laboral: fue uno de los periodos en que más se sancionaron leyes, decretos y normas ministeriales. Pero tuvieron otra dirección: fue para re-regular el funcionamiento del mercado de trabajo y hacerlo coherente con el modo de desarrollo. El resultado de ese proceso contradijo los postulados de la teoría neoclásica del mercado de trabajo: estos cambios para desregular, re-regular y flexibilizar no dieron como resultado el pleno empleo, sino por el contrario las tasas más elevadas de desempleo, de subempleo, de trabajo no registrado, de pobreza e indigencia a lo largo de la historia económica y social argentina. En el presente documento, se realiza el mismo ejercicio, pero en el periodo de la post-convertibilidad (2002-2009). Nuevamente se pudo verificar la hipótesis de que el mundo del trabajo argentino es plenamente dinámico y en transformación y que las normas se modificaron en varias direcciones, al impulso de los cambios estructurales del sistema productivo, que a su vez los condicionan. No hay determinismos, la relación es dialéctica y refleja la correlación de las fuerzas sociales en pugna. El contenido central del documento sigue una estructura similar al anterior. La introducción se propone caracterizar y sistematizar los cambios ocurridos durante la vigencia del régimen de convertibilidad en las instituciones y normas laborales, procurando encontrar la lógica subyacente. Es una visión sintética y de conjunto inspirada en el primer documento. Lo denominaremos "La herencia recibida. El punto de partida"

Effects of reproductive stage and temperature on rates of oxygen consumption in Paralithodes platypus (Decapoda: Anomura) Romero, Maria Carolina; Tapella, Federico; Stevens, Bradley; Loren Buck, C. Paralithodes platypus is a large decapod that inhabits Alaskan and North Pacific waters. Females exhibit a biennial spawning cycle, requiring two years for production of fully mature oöcytes. We used respirometry and video recording to determine: 1) metabolic rates of brooding and post-brooding females, embryos, and larvae at different temperatures, 2) if females exhibit active brood care, 3) oxygen availability within the clutch, and 4) the timing of larval hatching. The rates of oxygen consumption (MO2) of brooding females was significantly higher than that of post-brooding females at night, but was similar during the day and increased significantly with temperature. MO2 of crab embryos did not differ with position in the clutch, whereas MO2 of zoeae averaged 4-fold higher than that of embryos. Larvae from the periphery of the embryo mass, either top or bottom, hatched prior to larvae from the middle of the clutch. Oxygen availability in the embryo mass varied significantly with position in the clutch; saturation was highest at the top (~ 91%), and lowest at the middle (~ 66%). Flapping of the pleon in brooding females was coincident with sudden increases in oxygen availability at the bottom of the embryo mass. The percentage of time that brooding females were engaged in flapping of the pleon was 30% higher at night than during the day. Our results address the cost of brooding in a lithodid crab and the effects of temperature on this behavior. The importance of pleonal flapping to ventilation of the embryo mass and alternative hatching mechanisms is discussed.

Weighted Best Local ||.|| - Approximation in Orlicz Spaces Cuenya, Hector Hugo; Favier, Sergio José; Levis, Fabián Eduardo; Ridolfi, Claudia Vanina In this paper we prove the existence of best multipoint local ||·||−approximation to a function f from an N−dimensional space SN for a suitable integer N. This problem is considered in an arbitrary Orlicz space for both the Luxemburg and the Orlicz norms when some bits of data are more important than others. For this purpose, we introduce the concept of || · ||−balanced integer.

Molecular diversity of peanut-nodulating rhizobia in soils of Argentina Bogino, Pablo Cesar; Banchio, Erika; Giordano, Walter Fabian RSα sequencing is a valuable tool for identification of bacterial strains, and for evaluating the genetic structure of indigenous rhizobial populations. The purpose of this study was to evaluate, qualitatively, the presence or absence of RSα fragment in peanut‐nodulating strains isolated from plants grown at four sites in central Argentina. RSα fragment was found in only three of 26 indigenous strains, and in one of three inoculant strains analyzed. In contrast to results from studies of other symbiotic nitrogen‐fixing bacteria, such as soybean‐nodulating strains, no correlation was found between generation time and presence of RSα sequence. Phylogenetic analysis of the 16S rRNA gene sequence grouped peanut‐nodulating strains into two clusters, Bradyrhizobium japonicum vs. B. elkanii, and showed divergence among strains positive for RSα sequence. Our results confirm the genetic diversity previously reported for various peanut‐nodulating rhizobial strains, and indicate that the RSα fragment is not applicable as a marker or tool for competition assays at the field or ecological level.

Molecular characterization of Sunflower chlorotic mottle virus: A member of a distinct species in the genus Potyvirus Bejerman, Nicolas; Giolitti, Fabián José; de Breuil, Soledad; Lenardon, Sergio Luis The complete nucleotide (nt) and deduced amino acid (aa) sequences of the C (common) and CRS (chlorotic ringspot) Argentine strains of SuCMoV have been determined. The SuCMoV-C RNA genome consists of 9,965 nt, whereas indels within the P1 coding region of SuCMoV-CRS make its genomic length 15 nt shorter. Nucleotide and aa sequence identities between the polyproteins of the C and CRS strains of SuCMoV were 92.3 and 95.6%, respectively. Pairwise comparisons between the polyproteins of the C and CRS strains of SuCMoV and the viruses of the Potato virus Y (PVY) subgroup revealed identities of 66.5-66.9% at the nt level and 69.7-69. 8% at the aa level. These results and phylogenetic analyses show that although SuCMoV strains cluster together with the potyviruses belonging to the PVY subgroup, SuCMoV should be considered a member of a distinct species in the genus Potyvirus. © 2010 Springer-Verlag.

Investigation of UPQC for Sag Compensation in Wind Farms to Weak Grid Connections Farias, M. F.; Battaiotto, Pedro Eduardo; Cendoya, Marcelo Gustavo In the last years, the wind power generation incorporated into standard grids has been increased significantly. This situation forced the revision of grid connection code requirements, to guarantee the reliability in systems with high wind power penetration. In case of events like voltage sags, wind farms must keep connected to power system avoiding power imbalance and even system collapse. For induction generator based wind farms connected to weak grids, such sag may lead to wind farm outage. Several strategies have been proposed in the literature, but often for full or partial amplitude voltage restoration, without caring phase jump associated to voltage sags. In this work a voltage sag compensation strategy is proposed for voltage magnitude restoration with phase jump compensation, and compared with a magnitude only restoration strategy. These strategies were implemented using a Unified Power Quality Compensator UPQC. A model of wind farm with induction generators connected to a weak grid system, including a detailed UPQC compensator was developed on simulation software. Then simulations were conducted in order to compare the proposed compensation strategy with previous methods. Results show a better wind farm performance in proposed strategy than that found in magnitude only compensation schemes. Also, the power rating of the compensators used in the proposed strategy is similar than the one that would be required in classical strategies. Thus, considering the improvement in performance, the proposed strategy is recommended in retrofitting the existing installed fixed speed induction generators based wind farms.

El Marx de Dussel: Notas acerca de la recepción dusseliana de la obra teórica de Karl Marx; The Marx of Dussel: Notes on dusselian receipt of the theoretical work of Karl Marx Teruel, Flavio Hernán A partir de su exilio en México, a mediados de la década del setenta del siglo pasado, Enrique Dussel se entrega a la tarea de "leer seria y directamente" la obra teórica de Karl Marx producida entre los años 1857 y 1882. Al cabo de diez semestres de arduo trabajo, el resultado es una interpretación novedosa de las cuatro redacciones de El Capital. En efecto, ante los ojos de Dussel la obra maestra de Karl Marx se revela no solo como un tratado de economía sino antes bien como uno de antropología y ética. Marx, afirma Dussel, "deconstruye la economía capitalista críticamente y la reconstruye antropológica y éticamente". Asimismo, Dussel descubre que la producción teórica de Marx quedó inconclusa y, sobre todo, abierta a futuros desarrollos. Para el filósofo mendocino es necesario, en nuestro tiempo, no solo reinterpretar la totalidad de la obra de Marx sino también continuar su labor teórica, en especial desde América Latina, para el estudio del capitalismo periférico latinoamericano. Nuestro interés es indicar aquellos elementos que constituyen lo novedoso en la interpretación dusseliana de la obra teórica de Marx.; From his exile in Mexico in the mid seventies of last century, Enrique Dussel is given the task of "reading seriously and directly" the theoretical work of Karl Marx produced between 1857 and 1882. After ten semesters of hard work, the result is a novel interpretation of the four drafts of The Capital. Indeed, in the eyes of Dussel, the masterpiece of Karl Marx is revealed not only as an economic treatise but rather as an anthropology and ethics. Marx "capitalist economy critically deconstructs and reconstructs anthropological and ethically". Moreover, Dussel finds that the theoretical yield of Marx was inconclusive and, above all, open to future developments. For the philosopher is needed in our time, not only reinterpret the whole work of Marx but also to continue his theoretical work, especially from Latin America, for the study of Latin American peripheral capitalism. Our interest is to indicate those elements which constitute the novelty in dusseliana interpretation of Marx's theoretical work.