Screening for antifungal activity in plants from central Argentina Palacios, Sara Maria; Ruiz, Gustavo; Carpinella, Maria Cecilia Ethanolic extracts from aerial parts of 71 native plants from Argentina were tested by bioautography on Thin Layer Chromatography (TLC) for their antifungal effects against pathogenic Fusarium verticillioides. The extracts of Aristolochia argentina (Aristolochiaceae), Flourensia oolepis (Asteraceae), Gaillardia megapotamica (Asteraceae), Salvia cuspidata (Lamiaceae) and Trichocline reptans (Asteraceae) at Minimum Inhibitory Concentrations (MICs) of 0.03 to 0.12 mg/spot were highly effective in inhibiting the fungal growth followed by extracts from Baccharis artemisioides (Asteraceae), Baccharis salicifolia (Asteraceae), Dalea elegans (Fabaceae), Heterothalamus alienus (Asteraceae), Lepechinia floribunda (Lamiaceae), Vernonia nudiflora (Asteraceae) and Zanthoxylum coco (Rutaceae) at MICs of 0.25 - 0.50 mg/spot. While, F. oolepis, T. reptans and A. argentina extracts proved most potent, with MICs of 0.03, 0.03 and 0.06 mg/spot, respectively. Further studies are required with extracts of the most active species in bioguided assay isolation to obtain new molecules with potent antifungal properties to control harmful fungi such as F. verticillioides.

Maximal operators, Riesz transforms and Littlewood–Paley functions associated with Bessel operators on BMO Betancor, J.J.; Chicco Ruiz, Anibal Leonardo; Fariña, J.C.; Rodríguez-Mesa, L. In this paper we study boundedness properties of certain harmonic analysis operators (maximal operators for heat and Poisson semigroups, Riesz transforms and Littlewood–Paley g-functions) associated with Bessel operators, on the space BMOo(R) that consists of the odd functions with bounded mean oscillation on R.

On state estimation in electric drives Leon, Enrique Andres; Solsona, Jorge Alberto This paper deals with state estimation in electric drives. On one hand a nonlinear observer is designed, whereas on the other hand the speed state is estimated by using the dirty derivative from the position measured. The dirty derivative is an approximate version of the perfect derivative which introduces an estimation error few times analyzed in drive applications. For this reason, our proposal in this work consists in illustrating several aspects on the performance of the dirty derivator in presence of both model uncertainties and noisy measurements. To this end, a case study is introduced. The case study considers rotor speed estimation in a permanent magnet stepper motor, by assuming that rotor position and electrical variables are measured. In addition, this paper presents comments about the connection between dirty derivators and observers, and advantages and disadvantages of both techniques are also remarked.

Phage adsorption to Lactobacillus plantarum: influence of physiological and environmental factors. Briggiler Marcó, Mariángeles; Reinheimer, Jorge Alberto; Quiberoni, Andrea del Lujan Bacteriophage infection of lactic acid bacteria (LAB) constitutes one of the major problems in the dairy industry, causing economic losses and a constant risk of low quality and/or unsafe foods. The first step in the phage biology is the adsorption on the host cell surface. In a previous study, a remarkable thermal, chemical and photocatalytic resistance was demonstrated by four phages of Lactobacillus plantarum (ATCC 8014-B1, ATCC 8014-B2, FAGK1 and FAGK2). In the present work, these phages were used to characterize the adsorption process on L. plantarum ATCC 8014. Clearly, the characterization of this process could increase the possibilities of design useful strategies in order to prevent phage infections. The influence of Ca(2+), temperature, pH and physiological cell state on phage adsorption was investigated. Burst sizes of phages ATCC 8014-B1 and ATCC 8014-B2 were 60 and 83 PFU/infective centre, respectively. The four phages exhibited a high infectivity even at pH 4 and pH 11. Calcium or magnesium ions were not indispensable for cell lysis and plaque formation, and more than 99% of phage particles were adsorbed either in the presence or absence of Ca(2+), after 15 min at 37 degrees C. Phage adsorption was only partially affected at 50 degrees C, while reached its maximum between 30 and 42 degrees C. The highest adsorption values (99.9%) were observed from pH 5 to 7, after 30 min at 37 degrees C. Adsorption rates decreased after the thermal inactivation of cells, though, when 20 microg/ml of chloramphenicol was used, adsorption values were similar on treated and untreated cells. All these results showed that the adsorption process was only partially affected by a few conditions: thermally killed host cells, an incubation temperature of 50 degrees C and pH values of 9 and 10. Nevertheless, and unfortunately, those conditions are not commonly applied during fermented food manufacturing, thus restricting highly the application of strategies currently available to reduce phage infections in industrial environments. This work also contributes to increase the currently knowledge on the biological aspects of L. plantarum bacteriophages.

Recorrido sobre las lenguas del Chaco y los aportes a la investigación lingüística Golluscio, Lucia Angela; Vidal, Alejandra Silvia El Chaco es una de las regiones más ricas de América del Sur, no sólo desde el punto de vista ecológico, sino en términos de su diversidad etnolingüística. Este artículo ofrece primero un panorama actualizado sobre las lenguas chaqueñas y su clasificación genealógica así como un estado del arte de las obras publicadas sobre las lenguas del Chaco argentino. Después de reseñar los estudios sobre sintaxis en las lenguas chaqueñas anteriores a este volumen de Amerindia, las autoras se centran en los planteos teóricos que emergen del estudio de la cláusula y las relaciones interclausales en esta área lingüística, haciendo hincapié en los sistemas de alineamiento, las clases de palabras, sus límites y superposiciones, la relacionalidad de los sustantivos, los distintos tipos de cláusulas y de predicados, los procesos de combinación de verbos y de enlace entre cláusulas a nivel oracional y discursivo. Por último, pasan revista a los aspectos en los cuales los trabajos compilados contribuyen a la discusión y profundización de todos esos temas.

Nonrandom assembly of bacterial populations in activated sludge flocs Ayarza, Joaquín M.; Guerrero, Leandro Demián; Erijman, Leonardo The aim of this work was to investigate the dynamics of assembly of bacterial populations in activated sludge flocs. We approached this question by following the development of active bacterial populations during floc development in four replicated lab-scale activated sludge reactors, in which solid retention time (SRT) was set at 4 days. The null hypothesis was that the similarities in community composition could be accounted for by the probability that the same organisms occur in more than one replicated reactor. Microscopic imaging showed that the size of flocs in reactors with biomass retention increased during the first few days until a steady-state size was reached. The diversity and community structure of the sludge in all reactors were analyzed during a period of up to ten SRT, using denaturing gradient gel electrophoresis (DGGE) of reverse-transcription polymerase chain reaction-amplified 16S rRNA. High rates of change in DGGE profiles from consecutive sampling points suggested a high level of dynamics in all reactors. This conclusion was confirmed by the application of the Raup and Crick probability-based similarity index (SRC) for the comparison of rRNA-based fingerprinting patterns, which indicated that bacterial communities within reactors were not significantly similar after three SRT (0.05 < SRC > 0.95) and became significantly dissimilar after five SRT (SRC < 0.05). More importantly, significant similarity between replicate reactors was observed at all times analyzed (SRC > 0.95). The fact that the patterns between replicates were more reproducible than expected by chance under highly dynamic conditions allowed us to reject the null hypothesis that activated sludge floc communities assemble randomly from the available source pool of bacteria. We suggest that communities progressively recruit from the available pool of bacterial species, each with particular ecological requirements that determine their time of emergence into the community. © 2009 Springer Science+Business Media, LLC.

Density and habitat use at different spatial scales of a guanaco population (Lama guanicoe) in the Monte desert of Argentina Acebes, Pablo; Traba, Juan; Malo, Juan E.; Ovejero Aguilar, Ramiro Jose Antonio; Borghi, Carlos Eduardo The first density estimates of a peripheral guanaco population and its habitat use at different spatial scales are presented for a protected area of Monte desert, Argentina. Transects were surveyed in the wet and dry seasons of 2005. All guanaco herds observed during systematic surveys using roads and tracks were GPS located and their habitat use was identified. Herd size differed significantly between the dry and wet seasons. Population densities differed between wet (0.10-0.12 individuals/km2) and dry seasons (0.60-0.75 individuals/km2). The population estimates ranged from 75 individuals (dry season) to 388 individuals (wet season). Guanacos showed differential habitat use, the first determinant being abiotic factors, such as topography, soil characteristics or microclimate conditions, animals being detected in rougher rocky substrata in the dry season and in open flat terrain in the wet season, followed by a mesoscale selection defined by plant communities. At the latter scale, guanaco preferentially used mixed creosote bushland and saltbush more intensively during the wet season, and open scrub and columnar-cactus slopes in the dry season. The estimated population of this protected area was small but its population density was within the range of other populations and was relatively high for this dry and unproductive area.

Cross-habitat variation in the phenology of a colonial spider: Insights from a reciprocal transplant study Fernández Campón, María Florencia In species with widespread distribution, populations found in markedly different environments can show differences in developmental traits. This, in time, can have an effect on reproductive success. Sources of variation in developmental traits can be genetic or environmentally induced. I examined the relationship between environmental and genetic influences on juvenile development in populations of the colonial spider, Parawixia bistriata, located at sites with different moisture regimes and associated environmental variables (e.g., prey availability). It was expected that individuals from different populations would show differences in developmental traits and that those differences will be associated with lower reproductive success at dry sites. I recorded the phenology and developmental traits of native and transplanted individuals in the field and estimated reproductive success based on clutch size. Colonies from wet versus dry sites showed different phenologies, with individuals at dry sites maturing later. Transplant results suggest plasticity in instar duration caused by environmental effects. Despite differences in resources and spider phenology, clutch sizes of native dry and wet populations were similar. Transplanted individuals, however, were differentially affected. Transplants from wet to dry sites (WD) showed lower growth rates and smaller clutches, whereas transplants from dry to wet sites had larger clutch sizes than in native habitat. Delayed maturation and failure to reproduce in WD individuals is associated with a lower tendency to capture prey in groups and less aggressive interactions during prey capture. Thus, despite negative environmental effects on development, dry native individuals have evolved non-developmental traits that allow successful reproduction.

Maximal operators, Riesz transforms and Littlewood-Paley functions associated with Bessel operators on BMO Betancor, J. J.; Chicco Ruiz, Anibal Leonardo; Fariña, J. C.; Rodriguez Mesa, L. In this paper we study boundedness properties of certain harmonic analysis operators (maximal operators for heat and Poisson semigroups, Riesz transforms and Littlewood– Paley g-functions) associated with Bessel operators, on the space BMOo(R) that consists of the odd functions with bounded mean oscillation on R.

El temor reverencial: un principio político en Hobbes y Vico Alarcón, Patricio Este artículo tiene como objetivo dilucidar la función que cumple el temor reverencial en el Leviatán de Thomas Hobbes y en la Scienza Nuova de Giambattista Vico como principio del mundo civil. Se centra la atención en la imaginación y en la religión como elementos fundantes de las instituciones humanas, analizando sus implicanciones.; This article aims to elucidate the role of ‘awe’ in Thomas Hobbes’s Leviathan and in Giambattista Vico’s Scienza Nuova as a principle of civilian world. The focus is on imagination and religion as foundational elements of human institutions, analyzing its implications.

Self-assembly of a silylated steroid-based organogelator and its use as template for the in situ sol-gel polymerization of tetraethyl orthosilicate Edelsztein, Valeria Carolina; Burton, Gerardo; Di Chenna, Pablo Hector In this paper we report the synthesis of a new steroid-based low-molecular weight organogelator, the analysis of the self-assembled fibrilar network (SAFIN) and its use as template for the preparation of SiO2 nanotubes. This novel steroidal organogelator has a unique structure among the well known family of steroid-based organogelators, the most important characteristic of this molecule is the presence of a silyl ether group at C-3 together with a 6β,19-oxo bridge. It was capable to gelate hydrocarbons and tetraethyl orthosilicate at very low concentrations (<1 wt %). An insight into the aggregation mechanism is provided revealing that complementary interaction between an α-oriented hydrogen bond donor and a β-oriented acceptor on the steroid skeleton is the driving force for the primary 1D self-assembly. The SAFIN was successfully used as template to grow silica nanotubes (external diameter: 40-60 nm, internal diameter: 7 nm and several micrometers length) through a catalyst-free in situ co-assembly polymerization process. Hydrogen bond or electrostatic interactions between the anionic silicate intermediate species and the SAFIN are proposed to be the driving force for templating.

Lipase-catalyzed synthesis and characterization of a novel linear polyamidoamine oligomer Monsalve, Leandro Nicolas; Kaniz Fatema, M.; Nonami, Hiroshi; Erra Balsells, Rosa; Baldessari, Alicia A linear polyamidoamine oligomer was obtained by polymerization of ethyl acrylate and N-methyl-1,3-diaminopropane, catalyzed by the Candida antarctica lipase. Depending on the reaction conditions such as substrates concentration, solvent and enzyme:substrate ratio, the enzyme catalyzes the polymerization reaction or Michael adducts formation. The polymeric material, characterized by FTIR, 1H and 13C NMR and UV-MALDI-TOF-MS, shows low molecular weight and high monodispersity. The activity showed by C. antarctica lipase in the polymerization reaction is highly selective and allows to obtain a product with potential biomedical applications in mild condition reactions and low environmental impact.

Convexity properties of the condition number Beltran, Carlos; Dedieu, Jean Pierre; Malajovich, Gregorio; Shub, Michael Ira We define in the space of n×m matrices of rank n, n ≤ m, the condition Riemannian structure as follows: For a given matrix A the tangent space at A is equipped with the Hermitian inner product obtained by multiplying the usual Frobenius inner product by the inverse of the square of the smallest singular value of A denoted σ n(A). When this smallest singular value has multiplicity 1, the function A → log(σ n(A) -2) is a convex function with respect to the condition Riemannian structure that is t → log(σ n(A(t)) -2) is convex, in the usual sense for any geodesic A(t). In a more abstract setting, a function α defined on a Riemannian manifold (M, 〈, 〉) is said to be self-convex when log α(γ(t)) is convex for any geodesic in (M, α 〈, 〉). Necessary and sufficient conditions for self-convexity are given when α is C 2. When α(x) = d(x,N) -2, where d(x,N) is the distance from x to a C 2 submanifold N ⊂R j, we prove that α is self-convex when restricted to the largest open set of points x where there is a unique closest point in N to x. We also show, using this more general notion, that the square of the condition number ∥A∥ F /σ n(A) is self-convex in projective space and the solution variety.

Theoretical and experimental study of electrochemical reactors with three-dimensional bipolar electrodes Gonzalez Perez, Omar; Bisang, Jose Maria A mathematical model to represent three-dimensional bipolar electrodes is proposed taken into account the leakage current. The model is analytically solved when the electrochemical reaction has a mass-transfer control at low overpotentials, which represents a limiting case of the general mathematical treatment. For this simplified situation, expressions are deduced to evaluate the current and potential distribution and to calculate the leakage current. The effect on the leakage current of kinetic, electrochemical and geometric variables, which are lumped into one dimensionless number, is discussed. The influence of the leakage current on the optimal bed depth under limiting current conditions is also analyzed. Likewise, experimental data, using the deposition-dissolution of copper as test reaction, are compared with the theoretical prediction of the general treatment achieving a good agreement between both.

Successful experiment?: on Chile’s experience with territorial use rights in fisheries Orensanz, Jose Maria; Parma, Ana María Chile’s experience with territorial use rights in fi sheries shows their potential for the management of coastal resources, provided some simple safeguards are put in place.

Occurrence of the Tamarix Leafhopper, Opsius stactogalus Fieber (Hemiptera: Cicadellidae), in Argentina Virla, Eduardo Gabriel; Logarzo, Guillermo Alejandro; Paradell, Susana Liria The paleartic tamarix leafhopper,Opsius stactogalusFieber (Hemiptera: Cicadellidae), can reduce the growth of tamarisk due to the aggregate feeding imposed by their populations. The species was mentioned for Argentina in Metcalf´s catalogue (1967) without locality or region reference, and the contributions on Cicadellidae published by many authors after Metcalf omitted this distributional data. Populations of O. stactogalus on Tamarix sp. were found in 12 sites between 28º 48’ to 39º 17’ S and 64º 06’ to 70º 04’ W, located in both the Neotropical and Andean biogeographic regions.

From fresh water to the slope: fish community ecology in the Río de la Plata and the sea beyond; Desde el agua dulce hasta el talud: ecología de comunidades de peces en el Río de la Plata y el mar adyacente Garcia, Mirta Lidia; Jaureguizar, Andrés Javier; Protogino, Lucila Cristina The spatial pattern of fish assemblages and its relationship with factors along an environment gradient, from fresh to marine water environment along the Río de la Plata estuary (36ºS, 56ºW) the shelf and part of the slope, was examined using data from 22 sampling stations. Fish were sampled from all station with an Engel type trawl (200 mm stretched mesh in the wings, 120 mm stretched mesh in the cod ends, 4 m vertical opening and 15 m horizontal aperture) towed at 4 knots for 20 to 30 min per set. Cluster analysis and ordination analysis MDS were used to define spatial distribution of fish assemblages based on fish composition (abundance and biomass). BIO-ENV process was used to estimate assemblage association with depth, temperature and salinity of surface and bottom waters. The results of these analyses showed that the fish community along the riverine-marine gradient was structured in four assemblages: riverine, estuarine, shelf and slope. These assemblages were found to differ significantly in their species composition. Each assemblage was characterized by several common and discriminator species and characterized by differing environmental conditions. Bottom salinity and bottom temperature were the environmental variables most strongly associated with differences in assemblage structure across the various areas. The changes in assemblage structure between areas were gradual, with no sharp boundaries.; Se analizó el patrón espacial de las asociaciones de peces y su relación con los factores ambientales a lo largo del gradiente desde el agua dulce en el Río de la Plata hasta la parte superior del talud. Los peces fueron muestreados en 22 estaciones con una red de arrastre de fondo tipo Engel (200 mm de abertura de malla en las alas, 120 en el copo, 4 m de abertura vertical y 15 m de abertura horizontal) con una velocidad de arrastre de 4 nudos durante 20 a 30 min. Para definir la distribución espacial de las asociaciones de peces basadas en la composición de la ictiofauna (abundancia y biomasa) se aplicó el análisis de agrupamiento jerárquico y el análisis de ordenación MDS y para estimar la relación entre estas asociaciones con la profundidad, la temperatura y la salinidad del agua en la superficie y el fondo, se utilizó el proceso BIOENV. Los resultados obtenidos demuestran que en la comunidad de peces a lo largo de este gradiente riverino marino se pueden establecer cuatro asociaciones: riverina, estuarial, plataforma y talud. Estas asociaciones fueron significativamente diferentes en la composición de especies, cada una de ellas fue caracterizada por varias especies comunes y discriminantes y presentó diferentes condiciones ambientales. Concluimos que la salinidad y temperatura de fondo fueron las variables ambientales determinantes de la estructura de las asociaciones a través de las áreas. El cambio en la estructura entre las áreas fue gradual y con limites flexibles.

Catalog of the Types of Tenebrionidae and Perimylopidae (Insecta, Coleoptera) Deposited at Museo de La Plata (Argentina) Cabrera, Nora Clara; Fernandez, Liliana Alicia; Flores, Gustavo Ernesto; Lattari, Mariano The 224 types of species of Tenebrionidae and Perimylopidae (Coleoptera) housed in the collection of the Entomology Department of Museo de La Plata up until December 2008 were examined and listed; 96 names are recorded, 39 of them (41 percent) are represented by name bearing types (“primary” types). These 224 types belong to 85 species and 9 subespecies of Tenebrionidae assigned to the following subfamilies: Diaperinae (3 species, 3 types), Lagriinae (4 species, 9 types), Pimeliinae (53 species, 1 subspecies, 128 types), Stenochiinae (7 species, 10 types) and Tenebrioninae (18 species, 8 subspecies, 72 types), and 2 types belonging to 2 species of Perimylopidae. Species and subespecies herein treated were described by Berg (23), Burmeister (1), Bruch (1), Fairmaire (8), Flores & Carrara (1), Flores & Roig-Juñent (1), Flores & Vidal (2), Freude (2), Kulzer (27), Molinari (7), Müller (2), Peña (14), Peña & Barría (2), Pic (3), Steinheil (1) and Viana (1). Complete information is given for each type, including reference to original description, and label data. Two lists were added in order to support future research: one for specimens labelled as types but not found in the bibliography and seemingly not published and another for specimens labelled as types but not included in the original series.

GH modulates hepatic epidermal growth factor signaling in the mouse. Gonzalez, Lorena; Díaz, María Eugenia; Miquet, Johanna Gabriela; Sotelo, Ana Isabel; Fernandez, Diego Carlos; Dominici, Fernando Pablo; Bartke, Andrzej; Turyn, Daniel Epidermal growth factor (EGF) is a key regulator of cell survival and proliferation involved in the pathogenesis and progression of different types of cancer. The EGF receptor (EGFR) is activated by binding of the specific ligand but also by transactivation triggered by different growth factors including GH. Chronically, elevated GH levels have been associated with the progression of hepatocellular carcinoma. Considering EGF and GH involvement in cell proliferation and their signaling crosstalk, the objective of the present study was to analyze GH modulatory effects on EGF signaling in liver. For this purpose, GH receptor-knockout (GHR-KO) and GH-overexpressing transgenic mice were used. EGFR content was significantly decreased in GHR-KO mice. Consequently, EGF-induced phosphorylation of EGFR, AKT, ERK1/2, STAT3, and STAT5 was significantly decreased in these mice. In contrast, EGFR content as well as its basal tyrosine phosphorylation was increased in transgenic mice overexpressing GH. However, EGF stimulation caused similar levels of EGFR, AKT, and ERK1/2 phosphorylation in normal and transgenic mice, while EGF induction of STAT3 and STAT5 phosphorylation was inhibited in the transgenic mice. Desensitization of the STATs was related to decreased association of these proteins to the EGFR and increased association between STAT5 and the tyrosine phosphatase SH2-containing phosphatase-2. While GHR knockout is associated with diminished expression of the EGFR and a concomitant decrease in EGF signaling, GH overexpression results in EGFR overexpression with different effects depending on the signaling pathway analyzed: AKT and ERK1/2 pathways are induced by EGF, while STAT3 and STAT5 activation is heterologously desensitized.

A Simple Combinatorial Criterion for Projective Toric Manifolds with Dual Defect Dickenstein, Alicia Marcela; Nill, Benjamin We show that any smooth lattice polytope P with codegree greater or equal than (dim(P) + 3)/2 (or equivalently, with degree smaller than dim(P)/2), defines a dual defective projective toric manifold. This implies that P is Q-normal (in the terminology of [11]) and answers partially an adjunction-theoretic conjecture by BeltramettiSommese (see [5],[4],[11]). Also, it follows from [24] that smooth lattice polytopes with this property are precisely strict Cayley polytopes, which completes the answer in [11] of a question in [1] for smooth polytopes.