Diagnóstico de comunidades vegetales con análisis geomorfológico en la región árida oriental de Tulum; Relationship between plant communities and geomorphological environments in the arid region of Eastern Tulum Ortega, Andres; Flores, Daniel Germán; Suvires, Graciela Mabel En el este de la Depresión de Tulum, región desértica del centro y oeste de la Argentina, se efectuó un análisis entre las unidades geomorfológicas, procesos y texturas de los suelos, con el fin de establecer vinculaciones entre estos recursos y diagnosticar las comunidades de vegetación. Se identificaron y clasificaron tres principales ambientes geomorfológicos: un relieve dunar, una planicie arenosa eólica loessoide y una planicie fluvial abandonada del río San Juan. Se trazaron 3 transectas para relevar la vegetación y las texturas de los suelos. En el ambiente dunar actual, con procesos eólicos, domina Panicum urvellanum; en la planicie arenosa loessoide, con procesos fluviales antiguos y eólicos, Suaeda divaricata asociada a Atriplex lampa y Schismus barbatus, y en la planicie fluvial antigua, con procesos de salinización, Atriplex crenatifolia. La mayor riqueza y diversidad de especies se encontraron en la planicie arenosa loessoide y en suelos limosos y la menor en la planicie fluvial antigua, y suelos arcillosos correspondiendo a S2 y S3, respectivamente.; A multidisciplinary analysis was carried out to determine geomorphological units in the desert region of central and west Argentina and their relationship with plant communities. Three east-west transects were studied, resulting in the identification and classification of three main geomorphological environments: a dune relief, a sandy loess plain and an ancient fluvial plain of the San Juan River. The dominant plant community in the dune environment, characterized by wind processes, was found to be Panicum urvellanum; in the sandy loess plain, characterized by wind and ancient fluvial processes, Suaeda divaricata in association with Atriplex lampa and Schismus barbatus predominates; and in the ancient fluvial plain, where salt processes occur, Atriplex crenatifolia is the main community. The richest abundance and widest diversity were found in the sandy loess plain and in silty soils and the least abundance and diversity in the ancient fluvial plain and S2 and S3 clay soils.

Evaluation of herbicides for chemical weed control in lily bulb production Marinangeli, Pablo Alejandro; López Castro, Ramón Ignacio; Facchinetti, Cecilia; Reinoso, Lucio Gabriel; Irigoyen, Jorge Horacio; Curvetto, Nestor Raul Information on chemical weed control in lily bulb production in South America is scarce. Greenhouse and field studies were conducted to evaluate the phytotoxic effect and weed control of herbicides applied PRE and POST in lily bulb production in Argentina. In greenhouse studies, bromoxynil, 415 g ai ha-1; fluroxypyr, 200 g ai ha-1; metsulfuron, 3 g ai ha-1; iodosulfuron-methyl-sodium, 3 g ai ha-1 metsulfuron, 3 g ai ha-1; oxyfluorfen, 240 g ai ha-1; ioxynil, 529 g ai ha-1; and linuron, 750 g ai ha-1, produced severe phytotoxicity or death of bulbs. Glyphosate at 720 g ai ha-1 and aclonifen at 720 g ai ha-1 produced little to no symptoms and were considered safe to apply to lilies. In field conditions, PRE herbicides metolachlor, 960 g ai ha-1 atrazine, 1,500 g ai ha-1, and metolachlor, 960 g ai ha-1 flumetsulam, 80 g ai ha-1, provided good weed control but were phytotoxic for lily plants, with chlorosis as the main symptom. Metolachlor plus linuron resulted in little or no symptoms of injury and no reduction in bulb yield. Diuron, 800 g ai ha-1 POST was the most effective treatment without phytotoxicity, and, in combination with metolachlor, 960 g ai ha-1 linuron, 750 g ai ha-1 PRE, controlled weeds until 40 d after diuron application without yield reduction. Results obtained with glyphosate indicate that the Lilium genus presents some tolerance to this herbicide, which justifies further evaluation for weed control in lily bulb production.

Structural and spectroscopic evidence of strong electronic delocalization through a cyanido bridge in a mixed-valence Os-Ru complex Rossi, Melina Brenda; Abboud, Khalil A.; Alborés, Pablo; Baraldo Victorica, Luis Mario We report the properties of a trinuclear cyanido-bridged complex, trans-(dmap)4RuII(Âμ-NC)OsIII(CN) 524- [14-; dmap = 4-(dimethylamino)pyridine], whose structure and electronic and vibrational spectra present strong evidence of partial redox states for the three metal ions, an unprecedented feature for cyanido-bridged systems. Matching the energy of metal fragments bonded by a cyanido bridge results in asystem that is better described as having partial RuII/III and OsII/ III character as evidenced by its structure and its spectroscopic analysis.

Dynamic Complementarities, Efficiency and Nash Equilibria for Populations of Firms and Workers Accinelli, Elvio; London, Silvia; Punzo, Lionello F.; Sanchez Carrera, Edgar J. We consider an economy with two types of firms (innovative and non-innovative) and two types of workers (skilled and unskilled), where workers´ decisions are driven by imitative behavior, and thus the evolution of such an economy depends on the initial distribution of the firms. We show that there exists a continuous of high level steady states and only one low level and asymptotically stable equilibrium. There exists a threshold value on the initial number of firms to be overcome it to located in the basin of attraction of one of the high level equilibrium. We show that in each high level equilibrium there coexists a share of innovative firms with a share of non-innovative firms, and a share of skilled workers (human capital) coexisting with a share of unskilled workers. But if the initial share of innovative firms is lowerthan the threshold value, then the economy evolves to a low level equilibrium wholly composed by non-innovative firms and unskilled workers. Finally, we characterise the equilibria as the evolutionarily stable strategies against a field.

Characterization of biominerals in species of Canna (Cannaceae) Baran, Enrique José; Gonzalez Baro, Ana Cecilia; Ciciarelli, María de Las Mercedes; Rolleri, Cristina Hilda Plant biominerals are not always well characterized, although this information is important for plant physiology and can be useful for taxonomic purposes. In this work, fresh plant material of seven wild neotropical species of genus Canna, C. ascendens, C. coccinea, C. indica, C. glauca, C. plurituberosa, C. variegatifolia and C. fuchsina sp. ined., taken from different habitats, were studied to characterize the biominerals in their internal tissues. For the first time, samples from primary and secondary veins of leaves were investigated by means of infrared spectroscopy, complemented with X-ray powder diffractometry and scanning electron microscopy. The spectroscopic results, supported by X-ray powder diffractometry, suggest that the calcium oxalate is present in the form of whewellite (CaC2O4×H2O) in all the investigated samples. It is interesting to emphasize that all IR spectra obtained were strongly similar in all species studied, thus indicating an identical chemical composition in terms of the biominerals found. In this sense, the results suggest that the species of Canna show similar ability to produce biogenic silica and produce an identical type of calcium oxalate within their tissues. These results can be an additional trait to support the relationship among the families of Zingiberales.

Risedronate metal complexes potentially active against Chagas disease Demoro, Bruno; Caruso, Francesco; Rossi, Miriam; Benítez, Diego; Gonzalez, Mercedes; Cerecetto, Hugo; Parajón Costa, Beatriz Susana; Castiglioni, Jorge; Galizzi. Melina; Docampo, Roberto; Otero, Lucía; Gambino, Dinorah In the search for new metal-based drugs for the treatment of Chagas disease, the most widespread  Latin American parasitic disease, novel complexes of the bioactive ligand risedronate (Ris, (1-hydroxy-1-phosphono-2-pyridin-3-yl-ethyl)phosphonate), [MII(Ris)2]•4H2O, where M = Cu, Co, Mn and Ni, and [NiII(Ris)2(H2O)2]•H2O were synthesized and characterized by using analytical measurements, thermogravimetric analyses, cyclic voltammetry and infrared and Raman spectroscopies. Crystal structures of [CuII(Ris)2]•4H2O and [NiII(Ris)2(H2O)2]•H2O were solved by single crystal X-ray diffraction methods. The complexes, as well as the free ligand, were evaluated in vitro against epimastigotes and intracellular amastigotes of the parasite Trypanosoma cruzi, causative agent of Chagas disease. Results demonstrated that the coordination of risedronate to different metal ions improved the antiproliferative effect against Trypanosoma cruzi, exhibiting growth inhibition values against the intracellular amastigotes ranging the low micromolar levels. In addition, this strong activity could be related to high inhibition of farnesyl diphosphate synthase enzyme. On the other hand, protein interaction studies showed that all the complexes strongly interact with albumin thus providing a suitable means of transporting them to tissues in vivo.

Hábitos Alimentarios de Hyalella Curvispina Shoemaker, 1942 (Amphipoda: Gammaridea) en Ambientes Leníticos de la Llanura Aluvial del Río Paraná Medio Saigo, Miguel; Marchese Garello, Mercedes Rosa; Montalto, Luciana La asignación de los organismos a los grupos funcionales tróficos queda aún por resolver en la Región Neotropical ya que, generalmente se utilizan clasificaciones realizadas para especies de la Región Holártica. Así, Hyalella curvispina es citada como triturador, depredador, raspador y colector-recolector. El objetivo del trabajo fue determinar el grupo funcional trófico que integra H. curvispina. La hipótesis fue que H. curvispina consume preferentemente tejido vegetal, clasificándose en la categoría de triturador. Se recolectaron 30 individuos adultos para analizar su ingesta en tres ambientes leníticos durante el período abril-agosto del 2009. Los valores medios de las proporciones de cada ítem alimentario para los ambientes estudiados fueron: detritos 66,3%; tejido vegetal 28,2%; tejido animal 4,4% y algas 1,4%. Se encontraron diferencias significativas (p<0,01) en los ítems consumidos por los organismos entre las lagunas. No se observaron diferencias significativas en el consumo entre machos y hembras (p<0,01). Se concluye que H. curvispina integra el grupo funcional de los colectores recolectores, siendo además un triturador facultativo.

Estudio de factores de riesgo asociados a la infección por Mycoplasma suis Pereyra, N. B.; Pérez, A. M.; Messick, J. B.; Cane, F. D.; Guglielmone, Alberto Alejandro Este estudio se propuso estimar la distribución de la infección por Mycoplasma suis en poblaciones de cerdos de Argentina e identifi car factores de riesgo asociados. Se recolectaron 284 muestras de sangre de cerdos de diferentes categorías productivas en frigorífi cos y granjas de las provincias de Santa Fe, Córdoba y Buenos Aires. Amplifi cando el gen del ARNr 16S de M. suis a través de la reacción en cadena de la polimerasa (PCR), se calculó un porcentaje de infectados del 64%. Se estimó además que no existía asociación estadísticamente signifi cativa (p>0,1) entre un resultado positivo a la PCR y el sexo del animal muestreado, los antecedentes de anemia en la granja y las condiciones de alojamiento. Contrariamente se encontró asociación signifi cativa (p<0,1) con el origen geográfi co y la categoría productiva. Se estimó que los cerdos de Buenos Aires y Córdoba tenían más probabilidades de ser PCR positivos que los de Santa Fe, mientras que los lechones y los cerdos de recría tenían menos riesgo de infectarse que los animales de más edad. Se concluye que el M. suis está ampliamente distribuido en las poblaciones porcinas estudiadas del país.

Las crisis como “catalizadoras” del derecho: el caso de las recientes crisis alimentarias en la Unión Europea y la instauración del concepto de Seguridad Alimentaria Marichal, Maria Eugenia Este artículo analiza los procesos por los cuales importantes conceptos jurídicos e instituciones se originan para dar respuesta a crisis concretas, a partir del caso paradigmático del surgimiento del concepto de Seguridad Alimentaria en el Derecho Europeo luego de las crisis alimentarias sufridas a mediados de los ´80 y en los ´90. Se intentan describir las razones económicas, sociales y científicas que condujeron a las autoridades europeas, cuya atención estaba originalmente enfocada en la libre circulación de los bienes, hacia una creciente preocupación por la salud de los consumidores y el ambiente. Primero, brevemente se relata las mencionadas crisis alimentarias que evidenciaron la necesidad de nuevos instrumentos legales. Segundo, se delinean los principales rasgos de nueva legislación y las instituciones diseñadas para lidiar con estos problemas. Tercero, luego de una caracterización de la regulación existente antes de las crisis, se describen las herramientas jurídicas y las prácticas institucionales que cambiaron a raíz de la introducción de la Seguridad Alimentaria. Finalmente, esbozamos cómo el principio precautorio fue ampliado desde el derecho ambiental hacia el derecho alimentario en Europa para hacer frente al problema de la incerteza científica en esta área.

Rotating Nanoparticle Array Electrode for the Kinetic Study of Reactions under Mixed Control Montero, María de Los Angeles; Gennero, Maria Rosa; Chialvo, Abel Cesar A method for the determination of the intrinsic electrocatalytic activity of metal nanoparticles for reactions under mixed diffusion-activation control is proposed. The working electrode consists of a nanoparticle array supported on a rotating disc of an inert conducting substrate. This electrode configuration reduces significantly the contribution of the reactant diffusion to the experimental current-potential curves and consequently, the kinetic parameters of the reaction can be evaluated more accurately. A model was developed for the diffusion process in the proposed configuration, which includes a parameter related to the degree of dispersion of the nanoparticles on the electrode surface (active area factor). It allows one to evaluate changes in the current-potential plot under conditions of constant particle diameter, which is essential for the appropriate analysis of the electrocatalytic activity of nanoparticles. On this basis the dependences of the current and current density for the hydrogen oxidation reaction on overpotential, rotation rate, particle size and active area factor were derived. The validity of these expressions was verified through the analysis of experimental results.

Morphological characteristics of soybean root apexes as indicators of soil compaction Ramos, Julio Cesar; Imhoff, Silvia del Carmen; Pilatti, Miguel Angel; Vegetti, Abelardo Carlos Plant soil compaction poses a serious problem to agriculture because it produces different types of changes in plant characteristics. No method has been implemented to date to use root morphological changes as indicators of soil compaction levels. Therefore, the aim of the present study was to evaluate whether or not the morphological changes in root apexes of soybean (Glycine max (L.) Merrill) can be used as indicators of soil compaction levels. To this end, a silt-loamy soil material (from a Typic Argiudoll, Esperanza series), sieved through a 2 mm mesh was used and the following soil bulk density levels were determined: 1.1, 1.3 and 1.5 g cm–3 for which the corresponding mechanical resistances were < 0.1, 0.5 and 3.5 MPa, respectively. The distance from the apex to the first tertiary root and the root diameter at 1.5 cm from the apex were measured on the secondary root apexes. A form factor equal to the quotient between these two variables was subsequently calculated. An inverse relationship between soil mechanical impedance and secondary root length and form factor as well as a direct relationship with the secondary root diameter were observed. Changes in rhizodermis cells were also recorded. The following morphological characteristics were found to evidence the highest sensitivity to soil compaction: i) the form factor, ii) rhizodermis papillose cells, iii) apical malformations in root hairs, and iv) root diameter in expansion areas. Taken together, the morphological characteristics of root apexes could be considered to be indicative of soil compaction.

WT-1 mRNA expression is modulated by nitric oxide availability and Hsp70 interaction after neonatal unilateral ureteral obstruction Mazzei, Luciana Jorgelina; García, Isabel Mercedes; Cacciamani, Valeria; Benardon, María Eugenia; Manucha, Walter Ariel Fernando Wilms tumor gene 1 (wt-1), a key regulator of mesenchymal-epithelial transformation, is downregulated during congenital obstructive nephropathy, leading to apoptosis. There is a functional interaction between WT-1 and inducible nitric oxide synthase (iNOS). In this regard, we reported that after neonatal unilateral ureteral obstruction, rosuvastatin prevents apoptosis through an increase in nitric oxide bioavailability, which in turn is linked to higher Hsp70 expression. Hence, the goal of this study was to determine whether a nitric oxide/Hsp70 interaction is involved in changes in WT-1 mRNA expression after ureteral obstruction. Neonatal rats submitted to experimental ureteral obstruction were treated with either vehicle or rosuvastatin for 14 days. Decreased nitric oxide and iNOS/Hsp70 expression associated with WT-1 low expression was shown in obstructed kidneys. Apoptosis was induced and it was associated with an increased Bax/BcL2 ratio. Conversely, iNOS/Hsp70 upregulation and an increased WT-1 mRNA expression, without an apoptotic response, were observed in the cortex of obstructed kidneys of rosuvastatin-treated rats. Nitric oxide also modulated Hsp70 and WT-1 mRNA expression in MDCK cells. Finally, in vivo experiments with nitric oxide modulators support our hypothesis that WT-1 mRNA expression is associated with nitric oxide level. Results suggest that rosuvastatin may modulate WT-1 mRNA expression through renal nitric oxide bioavailability, preventing neonatal obstruction-induced apoptosis associated with Hsp70 interaction.

Nanoinsecticidas: Nuevas perspectivas para el control de plagas Stadler, Teodoro; Buteler, Micaela; Weaver, David K. La agricultura de bajo impacto ambiental demanda nuevos pesticidas que deben ajustarse a las exigentes normativas internacionales. Parte de la búsqueda de nuevos productos bio-acionales se desarrolla por fuera del marco de la síntesis orgánica, explorando diferentes sustancias de origen natural como extractos vegetales, aceites insecticidas e insecticidas inorgánicos. Los polvos insecticidas representan el grupo más antiguo de sustancias utilizadas por el hombre para el control de plagas, cuya eficacia se basa principalmente en fenómenos físicos. Con el advenimiento de los insecticidas de síntesis, los polvos insecticidas fueron relegados por casi cinco décadas a la función de carriers de principios activos dentro de los insecticidas formulados. Con el desarrollo del caolín hidrófobo en la década de los 90´, los polvos inorgánicos resurgieron como insecticidas ?per se?, y, recientemente, a partir del descubrimiento de los nanoinsecticidas, afloran nuevas alternativas para expandir el espectro de aplicaciones de los polvos inorgánicos. El desarrollo y registro de nuevos productos a partir de nanomateriales manufacturados se basa en el paradigma ?lo mismo pero diferente?, ya que éstos difieren de las sustancias con idéntica estructura y composición química respecto de algunas propiedades como reactividad, área especifica, efectos cuánticos, carga eléctrica, etc. Estas sustancias con nuevas propiedades también se destacan como herramientas muy prometedoras para la protección de cultivos y la producción de alimentos y abren nuevas fronteras para el manejo de plagas con nanoinsecticidas. La alúmina nanoestructurada exhibe varias de las propiedades del insecticida ideal, ya que se trata de un producto natural desde el punto de vista químico, no reactivo, económico, con reducidas probabilidades de provocar resistencia en los insectos y su eficacia es mayor que la de otros polvos insecticidas como el caolín o la tierra de diatomeas. La masiva aparición de productos a base de nanomateriales en el mercado ha superado la velocidad a la que se evalúa su potencial impacto, de modo que la aplicación avanza por delante de la regulación para su uso. Esto sugiere la urgente necesidad de investigar los potenciales riesgos que surgen del empleo de estos productos en general, de los nanoinsecticidas en particular y sus efectos sobre organismos no blancos, así como sobre las nuevas tecnologías de aplicación más seguras y eficientes. Los actuales niveles de aplicación de nanopartículas y los desarrollos por venir, sugieren que la nanotecnología tendrá un efecto directo sobre las tendencias de la evolución de la agricultura para el control de plagas.; Sustainable agriculture demands new environmentally friendly pesticides that adhere to strict international regulations. Part of the research on new biorational pesticides focuses on natural products such as plant extracts, oils, and inorganic insecticides. Insecticidal dusts represent the oldest group of substances used by men for pest management, and their efficacy is based on physical phenomena. With the advent of synthetic pesticides, insecticidal dusts were used as carriers for other active ingredients in formulated insecticides. Organic dusts made a come-back as insecticides with the discovery of hidrophobic kaolin in the 90's. Recently, the discovery of nanoinsecticides brings new alternatives to expand the spectrum of applications of inorganic dusts. Development and registry of nanomaterials is based on the idea that they are not new materials, although they have different properties than the products with the same chemical structure, given that novel properties emerge from products when they are at the nanoscale. For example, reactivity, specific area, electric charge and quantum effects may differ. These substances with new properties are promising as tools for crop protection and food production, opening new frontiers for nanoinsecticides in pest management. For example, nanostructured alumina has been shown to have insecticidal properties, and it possesses some of the characteristics of an ideal insecticide, given that it is a natural product, not reactive, economical, with reduced probabilities of generating resistance in insects, and it is more effective than other commercially available insecticidal dusts. The current use of nanotechnology in a wide array of fields and products as well as the recent discovery of their potential in crop protection suggests that nanomaterials have a great potential for development of new products that will impact agriculture. Given the recent and widespread use of nanomaterials, there is an urgent need to study the impact of these products on human health and non target organisms, as well as to research more efficient and safer delivery technologies. The current levels of application of nanoparticles and the expected developments to come, suggest that nanotechnology will have a direct impact on the evolution of pest management practices in agriculture.

Crowned eagles rarely prey on livestock in central Argentina: persecution is not justified Sarasola, José Hernán; Santillán, Miguel Ángel; Galmes, Maximiliano Adrian Raptors have been reported to prey on livestock, causing considerable conflicts between birds of prey and local human communities. Previous studies have documented that human persecution is the most important threat to the endangered crowned eagle Harpyhaliaetus coronatus in central Argentina, due to a local belief that crowned eagles heavily and consistently prey on livestock. However, there are no empirical data supporting this assertion. Such information is crucial to evaluating possible measures to mitigate this human–wildlife conflict. We evaluated the feeding ecology of crowned eagles in semiarid habitats of central Argentina during the breeding seasons of 2002 to 2009. We also evaluated whether eagles are responsible for livestock predation and examined spatial-temporal variation in crowned eagles’ food habits. We identified 598 prey items consisting almost entirely of native prey: mammals (67.7%), reptiles (16.2%), birds (3.3%), fish (2.5%), and invertebrates (16.9%). We only recorded 1 (0.17%) occurrence of livestock prey remains, belonging to a domestic goat Capra hircus. Occurrences of the 4 main prey groups were not affected by habitat type or season. However, reptiles were recorded in higher numbers at sites where the diet of eagles was addressed by direct observation and video recording. Contrary to other human–predator conflicts worldwide, and assuming that the single livestock prey was not scavenged, our results show that crowned eagles rarely prey on livestock. We advocate reducing human–wildlife conflicts by implementing management and conservation measures and by educating local communities with respect to the ecological role of crowned eagles and other predators.

Effect of abomasal glucose infusion on plasma concentrations of gut peptides in periparturient dairy cows Larsen, M.; Relling, Alejandro Enrique; Reynolds, C.K.; Kristensen, N. B. Six Holstein cows fitted with ruminal cannulas and permanent indwelling catheters in the portal vein, hepatic vein, mesenteric vein, and an artery were used to study the effects of abomasal glucose infusion on splanchnic plasma concentrations of gut peptides. The experimental design was a randomized block design with repeated measurements. Cows were assigned to one of 2 treatments: control or infusion of 1,500. g of glucose/d into the abomasum from the day of parturition to 29 d in milk. Cows were sampled 12 ± 6 d prepartum and at 4, 15, and 29 d in milk. Concentrations of glucose-dependent insulinotropic polypeptide, glucagon-like peptide 1(7-36) amide, and oxyntomodulin were measured in pooled samples within cow and sampling day, whereas active ghrelin was measured in samples obtained 30. min before and after feeding at 0800. h. Postpartum, dry matter intake increased at a lower rate with infusion compared with the control. Arterial, portal venous, and hepatic venous plasma concentrations of the measured gut peptides were unaffected by abomasal glucose infusion. The arterial, portal venous, and hepatic venous plasma concentrations of glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1(7-36) amide increased linearly from 12 d prepartum to 29 d postpartum. Plasma concentrations of oxyntomodulin were unaffected by day relative to parturition. Arterial and portal venous plasma concentrations of ghrelin were lower postfeeding compared with prefeeding concentrations. Arterial plasma concentrations of ghrelin were greatest prepartum and lowest at 4 d postpartum, giving a quadratic pattern of change over the transition period. Positive portal venous-arterial and hepatic venous-arterial concentration differences were observed for glucagon-like peptide 1(7-36) amide. A negative portal venous-arterial concentration difference was observed for ghrelin pre-feeding. The remaining portal venous-arterial and hepatic venous-arterial concentration differences of gut peptides did not differ from zero. In conclusion, increased postruminal glucose supply to postpartum transition dairy cows reduced feed intake relative to control cows, but did not affect arterial, portal venous, or hepatic venous plasma concentrations of gut peptide hormones. Instead, gut peptide plasma concentrations increased as lactation progressed. Thus, the lower feed intake of postpartum dairy cows receiving abomasal glucose infusion was not attributable to changes in gut peptide concentrations.

Minimum classification error learning for sequential data in the wavelet domain Tomassi, Diego Rodolfo; Milone, Diego Humberto; Forzani, Liliana Maria Wavelet analysis has found widespread use in signal processing and many classification tasks. Nevertheless, its use in dynamic pattern recognition have been much more restricted since most of wavelet models cannot handle variable length sequences properly. Recently, composite hidden Markov models which observe structured data in the wavelet domain were proposed to deal with this kind of sequences. In these models, hidden Markov trees account for local dynamics in a multiresolution framework, while standard hidden Markov models capture longer correlations in time. Despite these models have shown promising results in simple applications, only generative approaches have been used so far for parameter estimation. The goal of this work is to take a step forward in the development of dynamic pattern recognizers using wavelet features by introducing a new discriminative training method for this Markov models. The learning strategy relies on the minimum classification error approach and provides re-estimation formulas for fully non-tied models. Numerical experiments on phoneme recognition show important improvement over the recognition rate achieved by the same models trained using maximum likelihood estimation.

Risk assessment of genetically modified lactic acid bacteria using the concept of substantial equivalence Leblanc, Jean Guy Joseph; van Sinderen, Douwe; Hugenholtz, Jeroen; Piard, Jean Christophe; Sesma, Fernando Juan Manuel; Savoy, Graciela The use of food-grade microorganisms such as lactic acid bacteria (LAB) is one of the most promising methods for delivering health promoting compounds. Since it is not always possible to obtain strains that have the ability to produce specific compounds naturally or that produce them in sufficient quantities to obtain physiological responses, genetic modifications can be performed to improve their output. The objective of this study was to evaluate if previously studied genetically modified LAB (GM-LAB), with proven in vivo beneficial effects, are just as safe as the progenitor strain from which they were derived. Mice received an elevated concentration of different GM-LAB or the native parental strain from which they were derived during a prolonged period of time, and different health parameters were evaluated. Similar growth rates, hematological values, and other physiological parameters were obtained in the animals that received the GM-LAB compared to those that were fed with the native strain. These results demonstrate that the GM-LAB used in this study are just as safe as the native strains from which they were derived and thus merit further studies to include them into the food chain.

The oldest lower Upper Cretaceous plesiosaurs (Reptilia, Sauropterygia) from southern Patagonia, Argentina; Los Plesiosaurios (Reptilia, Sauropterygia) más antiguos del Cretácico Superior bajo de la Patagonia Austral, Argentina O'gorman, Jose Patricio; Varela, Augusto Nicolás Plesiosaurs are recorded for the first time from the lower section of Mata Amarilla Formation, Santa Cruz Province, Patagonia, Argentina. The stratigraphic succession consists of mudstones and siltstones interbedded with medium to fine-grained sandstone, deposited in a littoral environment during the Cenomanian-Santonian; therefore the material is the oldest record of plesiosaurs from the lower Late Cretaceous rocks of Argentina. The remains include teeth, some vertebrae, and one propodium assigned to Elasmosauridae indet. and Plesiosauria indet. The status of Polyptychodon patagonicus Ameghino, 1893, as well as its stratigraphic position are discussed, leading to the conclusion that the material described by Ameghino is probably from the Mata Amarilla Formation and can only be referred to Plesiosauria indet. Analysis of sedimentologic features suggests that the material described here was deposited in an estuarine environment, strongly influenced by tides. The characters of the inferred environment are consistent with the type of preservation of the materials; Se dan a conocer los primeros registros claramente referibles a plesiosaurios de la sección inferior de la Formación Mata Amarilla en la provincia de Santa Cruz, Argentina. Los niveles portadores están compuestos por limolitas y arcillitas grises y negruzcas, que alternan con bancos de areniscas finas y medianas. Dichos niveles se depositaron en un ambiente litoral durante el intervalo Cenomaniano-Santoniano, siendo por tanto el registro más antiguo de plesiosaurios del Cretácico Superior de Argentina. Los restos hallados corresponden a dientes, vértebras y un propodio asignados a Elasmosauridae indet. y a Plesiosauria indet. Se discute el estatus de Polyptychodon patagonicus Ameghino, 1893 y su posición estratigráfica, concluyendo que el material descripto por Ameghino es sólo referible a Plesiosauria indet. y que proviene de la sección inferior de la Formación Mata Amarilla. El análisis sedimentológico indica que los materiales que se describen aquí fueron depositados en un ambiente estuarino con fuerte influencia mareal. Las características del ambiente de depositación de esta sección son consistentes con el estado de preservación de los materiales

Internal anatomy of an erg sequence from the aeolian-fluvial system of the De La Cuesta Formation (Paganzo Basin, northwestern Argentina) Spalletti, Luis Antonio; Limarino, Carlos Oscar; Colombo Piñol, Ferran Permian red beds of the De La Cuesta Formation in the Sierra de Narváez (Paganzo Basin, northwestern Argentina) are essentially composed of sandstones associated with mudstones and subordinate conglomerates. Facies distributions and stacking patterns indicate that these sediments resulted from the interaction between aeolian and ephemeral fluvial systems, and are represented by aeolian dune, dry aeolian interdune and aeolian sand sheet, mudflat, wet aeolian interdune, and fluvial deposits. The De La Cuesta Formation is characterised by aeolian (erg) sequences alternating with non-aeolian (terminal alluvial fan - mudflat) sequences. Each erg sequence is bounded at its base by a regionally extensive sand-drift surface and at the top by an extinction surface. A number of architectural elements, including aeolian dunes limited by interdunes, grouped crescentic aeolian dunes, longitudinal dunes, and draa with superimposed crescentic dunes are recognised in the erg sequences. The sand sea developed during phases of increasing aridity, whereas non-aeolian deposition might have occurred during more humid phases. Thus, the styles of aeolian-fluvial interaction are considered to result from cyclical climatic changes. Within the drier hemicycles, the rhythmic alternation between draa deposits and aeolian dune and interdune deposits indicates higher frequency cycles that could be attributed to subtle climatic oscillations and/ or changes in sand supply and availability. The development of the Permian sand sea in the inland Paganzo Basin seems to be related to the growth of a volcanic chain to the west. This topographic barrier separated the Paganzo Basin from the Chilean Basin, located along the western margin of Gondwana and characterised by shallow marine carbonate sedimentation. The correlation between the Permian erg and the shallow marine carbonates suggests a regional warming period during the Middle Permian in western Gondwana.

Patrones de actividad en dos monos araña negro, Ateles paniscus, en la Reserva Experimental Horco Molle, Tucumán, Argentina: comparación con sus congéneres silvestres; Activity patterns in two black spider monkeys, Ateles paniscus, in the Experimental Horco Molle Reserve, Tucumán, Argentina: Comparison with wild relatives Lambruschi, Daniel Andrés; Halloy, Monique El estudio del comportamiento y de los patrones de actividad en vertebrados puede brindar herramientas que pueden ser útiles para estimar su bienestar. Cuánto más se asemejen estos patrones entre animales silvestres y en cautiverio, mayores serán las probabilidades de que estos últimos se encuentren en buen estado. Realizar actividades de enriquecimiento ambiental contribuye al bienestar de los animales cautivos. En este trabajo, se describen los comportamientos de dos individuos de mono araña negro, Ateles paniscus, un macho y una hembra, que habitan una pequeña isla artificial de 1400 m 2 en la Reserva Experimental Horco Molle, Tucumán. Se reportan patrones de actividad durante dos semanas no consecutivas y se realizan experimentos de enriquecimiento durante una semana intermedia con el objetivo de evaluar su bienestar y sugerir opciones de manejo orientadas a mejorar su calidad de vida. Los monos expresaron conductas típicas de la especie y con frecuencias similares a las citadas para poblaciones silvestres, indicio importante de su bienestar. Esto puede deberse en parte a donde están viviendo, una isla con árboles altos, lo que les da más espacio y diversidad. Los compor tamientos más frecuentes fueron descansar, estar alerta, locomoción y forrajear. A diferencia de sus congéneres silvestres, estuvieron la mayor parte del tiempo en el suelo. Dado el gran interés que mostraron ante los distintos enriquecimientos y dado que la búsqueda de comida constituye una actividad importante, generalmente realizada en el dosel de los árboles en monos silvestres, acciones destinadas a incrementar éstos podrían mejorar aún más su calidad de vida.; The study of behavior and activity patterns in vertebrates can provide tools that may be useful in estimating their well-being. The more these patterns are similar between wild and captive animals, the greater the probability that the latter are in good condition. Providing enrichment activities can contribute to the well-being of these animals. In this study, behaviors of two black spider monkeys, Ateles paniscus, a male and a female, residing in a small artificial island of 1400 m 2 in the Experimental Reserve of Horco Molle, Tucumán, are described. Activity patterns are reported for two non-consecutive weeks, with enrichment experiments performed during an intermediate week, in order to evaluate their well-being and suggest strategies that may contribute to their quality of life. The monkeys expressed typical behaviors for the species, with similar frequencies to those cited for wild populations, an important indication of its well-being. This may be due in part to the fact that they live on an island with trees, which gives them more space and diversity. The most frequent behaviors were resting, being alert, moving, and foraging. Contrary to their wild counterparts, they were most of the time on the ground. Given the great interest they showed when presented with different enrichment activities and given that the search for food is an impor tant activity, generally taking place in the canopy of trees in wild monkeys, actions destined to increase these activities could improve even more their quality of life.