An approach to argumentative reasoning servers with multiple preference criteria Teze, Juan Carlos Lionel; Gottifredi, Sebastián; García, Alejandro Javier; Simari, Guillermo Ricardo Argumentation is a reasoning mechanism of dialectical and non-monotonic na- ture, with useful properties of computational tractability. In dynamic domains where agents deal with incomplete and contradictory information, an argument comparison criterion can be used to determine the accepted information; ar- gumentation systems with a single argument comparison criterion have been widely studied. In some of these approaches the comparison criterion is fixed, while in others a criterion can be selected and replaced in a modular way. In this work, we introduce an argumentative server that provides recommendations to its client agents and the possibility of indicating under what conditions an argument comparison criterion can be chosen to answer a particular query. To achieve this, we formalize a special type of query which, by using a conditional expression, allows the server to dynamically choose a criterion. As a result, several properties of these expressions will be studied.

Banco de semillas, germinación y longevidad de semillas de retama (Spartium junceum): implicancias para su control; Seed bank, germination and seed longevity of Spanish broom (Spartium junceum, Fabaceae): implications for control. Sanhueza, Cristina del Carmen; Zalba, Sergio Martín La retama (Spartium junceum) es una especie invasora de pastizales naturales en las sierras australes bonaerenses. Estudiamos características del proceso de germinación que resultarían clave para su control. Calculamos densidad de semillas y porcentaje de germinación para muestras de suelo provenientes de sectores invadidos. Realizamos ensayos de germinación en panes de tierra mantenidos a la intemperie y ensayos en cámara de germinación con semillas colectadas directamente del arbusto y otras colectadas del banco del suelo siete años antes del ensayo. La densidad en el banco del suelo de áreas invadidas varió entre 600 y 4.411 semillas/m2. El porcentaje de germinación de semillas de ensayos en panes de tierra fue de 68,33±26,66%. Para los ensayos en cámara, la escarificación mecánica resultó 100% de germinación para semillas recolectadas de las plantas, contra 7±5,7% para el control y valores aún inferiores para shock térmico y combinación shock térmico+escarificación mecánica El ensayo de semillas con más de siete años resultó en un porcentaje de germinación del 88,73±11,16% para la escarificación mecánica, 85,77±10,50% para shock térmico, 40,30±10,14% para imbibición y 43,20±12,01% para el control. Altas temperaturas durante períodos cortos, lesiones en la cubierta seminal y disturbios del suelo favorecen considerablemente la germinación y estimulan los procesos de invasión.; The Spanish broom (Spartium junceum) is an exotic invader of natural grasslands in southern Buenos Aires mountains. We assessed the density of seeds in the soil seed bank and the percentage of germination in botanic garden experiments for samples obtained from three invaded sites. We performed essays outdoors for soil samples, and in germination chamber for seeds collected directly from plants and for seeds obtained from the soil seven years before the experiment. Seeds density in the soil ranged from 600 to 4411 seeds/m2. Germination percentage for soil samples was 68.33±26.66%. For chamber experiments, mechanical scarification lead to the germination of all the seeds in the case of those collected from the plants, compared to just 7±5.7% for the control and figures even smaller for heath shock and combination of heath shock and mechanical scarification. The experiment with seeds form the soil bank resulted in a percentage of germination of 88.73±11.16% for those seeds previously treated with mechanical scarification, 85.77±10.50% for heath shock, 40.30±10.14% for imbibitions and 43.20±12.01% for the control. Brief exposition to high temperatures, mechanical breakage of the seed cover and soil disturbances significatively favor germination and stimulate invasion.

Building a Species Conservation Strategy for the brown howler monkey (Alouatta guariba clamitans) in Argentina in the context of yellow fever outbreaks Agostini, Ilaria; Holzmann, Ingrid; Di Bitetti, Mario Santiago; Oklander, Luciana Inés; Kowalewski, Martín M.; Beldomenico, Pablo Martín; Goenaga, Silvina; Martinez, Mariela; Moreno, Eduardo S.; Lestani, Eduardo; Desbiez, Arnaud L.J.; Miller, Philip The brown howler monkey (Alouatta guariba clamitans) is endemic to South America’s Atlantic Forest, with a small population extending into the northern portion of Misiones province in northeastern Argentina. In 2012, the species was classified as Critically Endangered in Argentina due to its highly restricted distribution, low population density and dramatic declines from recent Yellow Fever outbreaks. In March 2013, we organized an international workshop in Misiones to evaluate population status in Argentina and conduct a threat analysis. We developed population viability models using Vortex and Outbreak software packages. These tools allowed us to explore how several biological and demographic parameters of brown howlers, as well as factors related to Yellow Fever epidemiology, affect the probability of species extinction. The discussion among diverse specialists and analysis of model results identified Yellow Fever as the main threat to brown howler population persistence in Argentina. Our threat analysis, focused on the dynamics of Yellow Fever outbreaks and their impact on howler populations, led to the identification of gaps in knowledge that helped prioritize objectives and actions for the development of a Species Conservation Strategy in Argentina.; El mono aullador marrón (Alouatta guariba clamitans) es endémico del Bosque Atlántico de América del Sur, con una pequeña población que se extiende en la porción norte de la provincia de Misiones en el noreste de Argentina. En el año 2012, debido a su reducida distribución geográfica, su baja densidad poblacional y al dramático impacto de los recientes brotes de Fiebre Amarilla, la especie fue categorizada en Argentina como “en peligro crítico”. En el mes de marzo de 2013 organizamos un taller internacional en Misiones con el objetivo de evaluar el estado de la población de esta especie en Argentina y llevar a cabo un análisis de las principales amenazas para su conservación. Para alcanzar estos objetivos construimos modelos de viabilidad poblacional utilizando los programas Vortex y Outbreak. Los mismos nos permitieron explorar cómo varios parámetros biológicos y demográficos de la especie, así como diversos factores relacionados al impacto de la Fiebre Amarilla, influyen sobre la probabilidad de extinción de la especie. La discusión entre los distintos especialistas y el análisis de los resultados de los modelos identificaron a la Fiebre Amarilla como la principal amenaza para la subsistencia de esta población en Argentina. El análisis de las amenazas se centró en la dinámica de los brotes de Fiebre Amarilla y la severidad de su impacto sobre la población de esta especie, lo que permitió identificar huecos en el conocimiento que permitieron priorizar objetivos y acciones a llevar a cabo para el desarrollo de una estrategia de conservación para esta especie en Argentina.

The Gondwana connections of northern Patagonia Pankhurst, R. J.; Rapela, Carlos Washington; Lopez, Monica Graciela; Rapalini, Augusto Ernesto; Fanning, C. M.; Galindo, C. A multidisciplinary study (U–Pb sensitive high-resolution ion microprobe geochronology, Hf and O isotopes in zircon, Sr and Nd isotopes in whole-rocks, as well as major and trace element geochemistry) has been carried out on granitoid samples from the area west of Valcheta, North Patagonian Massif, Argentina. These confirm the Cambrian age of the Tardugno Granodiorite (528 ± 4 Ma) and the Late Permian age of granites in the central part of the Yaminué complex (250 Ma). Together with petrological and structural information for the area, we consider a previously suggested idea that the Cambrian and Ordovician granites of northeastern Patagonia represent continuation of the Pampean and Famatinian orogenic belts of the Sierras Pampeanas, respectively. Our interpretation does not support the hypothesis that Patagonia was accreted in Late Palaeozoic times as a far-travelled terrane, originating in the Central Transantarctic Mountains, and the arguments for and against this idea are reviewed. A parautochthonous origin is preferred with no major ocean closure between the North Patagonian Massif and the Sierra de la Ventana fold belt.

Effect of Forward/Inverse Model Asymmetries Over Retrieved Soil Moisture Assessed With an OSSE for the Aquarius/SAC-D Mission Bruscantini, Cintia Alicia; Perna, Pablo Alejandro; Ferrazzoli, Paolo; Grings, Francisco Matias; Karszenbaum, Haydee; Crow, Wade T. An Observing System Simulation Experiment (OSSE) for the Aquarius/SAC-D mission that includes different models for forward and retrieval processes is presented. This OSSE is implemented to study the errors related to the use of simple retrieval models in passive microwave applications. To this end, a theoretical forward model was introduced, which is suitable to reproduce some of the complexities related to canopy vegetation scattering. So far, this OSSE has been successfully exploited to study the artifacts in the retrieved soil moisture associated to: 1) uncertainties and aggregation of the ancillary parameters needed for the retrieval, and 2) instrumental noise effects. In this paper, we attempt to model the influence of this model asymmetry (different forward and inverse model) in the estimated soil moisture. These asymmetries are related to the fact that the emissivity of real surfaces is complex and strongly dependent on land cover type and condition. In particular, surface covered by average to dense vegetation presents complex scattering properties, related to canopy structure. Using this theoretical model, the difficulties related to retrieving soil moisture from passive data with a simple model are studied. The accuracy of the soil moisture estimation is analyzed in order to illustrate the impact of discrepancies between both models. In general, retrieved soil moisture performs worse over dense vegetated areas and under wet conditions. Furthermore, accuracy is highly dependent on land cover.

Neurología genómica personalizada: el futuro es ahora; Personalized genomic neurology: Future is now Córdoba, Marta; Gonzalez Moron, Dolores; Rodríguez Quiroga, Sergio Alejandro; Kauffman, Marcelo Andres Introducción y objetivos: Las nuevas técnicas de secuenciación genómica masiva han revolucionado el diagnóstico de las enfermedades neurológicas. Nuestro objetivo general es ilustrar, mediante la presentación de 3 casos clínicos, el abordaje diagnóstico de la patología neurológica desde la genómica. Para ello nos proponemos: explorar herramientas bioinformáticas de anotación e interpretación funcional de variantes, describir un algoritmo de análisis para los datos obtenidos del exoma y con estos resultados correlacionar en nuestros pacientes fenotipo-genotipo-vía funcional. Material y métodos: Fueron incluidos 3 pacientes que concurrieron a la consulta con síntomas neurológicos crónicos y progresivos. Secuenciamos el exoma en los 3. Mediante el uso de herramientas bioinformáticas, utilizando un algoritmo de selección, se filtraron las variantes por frecuencia poblacional, patogenicidad y modelo de herencia. Se estableció la correlación funcional con el fenotipo en cada caso y finalmente se validaron las variantes candidatas por Sanger en los afectados y se buscó su segregación en familiares. Resultados: Se elaboraron algoritmos de aproximación diagnóstica genómica para cada caso. En el caso 1 se llegó al diagnóstico de leucodistrofia asociada a POLR3A con las siguientes mutaciones c.G3781A:p.E1261K y c.G3014A:p.R1005H. En el caso 2 el diagnóstico probable fue de retraso mental sindromático secundario a la mutación p.Arg198* en homocigosis para GRIK2. Y, finalmente, en el caso 3 la causa de paraparesia espástica hereditaria fue el haplotipo patogénico en heterocigosis compuesta c.6763insA y c.6726A>T, p.Gln2242His en SPG11. Conclusiones: La aproximación diagnóstica genómica en conjunto con una completa evaluación clínica resulta útil para el abordaje de la patología neurológica, permitiendo una correlación fenotipo genotipo y vía funcional afectada, arribando a un diagnóstico molecular sólido.; Introduction and objectives: The new techniques of mass genome sequencing have revolutionized the diagnosis of neurological diseases. Our overall objective is to illustrate the genomic diagnostic approach of neurological pathology by presenting three cases. To do this we will: explore bioinformatic annotation tools and functional interpretation of variants, describe an algorithm for exome data analysis and to correlate these results with our phenotype-genotype -functional pathway. Material and methods: We included 3 patients who attended the talks with chronic and progressive neurological symptoms. We sequenced the exome in all three. We performed the analysis through annotation and functional bioinformatic tools Results: Algorithms genomic diagnostic approach were developed for each case. In case 1 the diagnosis was reached Leukodystrophy associated with the following mutations POLR3A c.G3781A: p.E1261K and c.G3014A: p.R1005H. In case 2 the diagnosis was probable syndromic mental retardation secondary to homozygous mutation p.Arg198* for GRIK2. And finally in case 3 the cause of hereditary spastic paraparesis was compound heterozygous pathogenic haplotype c.6763insA and c.6726A > T, p.Gln2242His in SPG11. Conclusions: The genomic diagnostic approach along with a complete clinical evaluation is useful for addressing neurological pathology allowing genotype and phenotype correlation with functional pathways arriving to a solid molecular diagnosis.

Building a Species Conservation Strategy for the brown howler monkey (Alouatta guariba clamitans) in Argentina in the context of yellow fever outbreaks Agostini, Ilaria; Holzmann, Ingrid; Di Bitetti, Mario Santiago; Oklander, Luciana Inés; Kowalewski, Miguel Martin; Beldomenico, Pablo Martín; Goenaga, S.; Martínez, Mariela Florencia; Moreno, Eduardo S.; Lestani, Eduardo; Desbiez, Arnaud L. J.; Miller, Philip The brown howler monkey (Alouatta guariba clamitans) is endemic to South America?s Atlantic Forest, with a small population extending into the northern portion of Misiones province in northeastern Argentina. In 2012, the species was classified as Critically Endangered in Argentina due to its highly restricted distribution, low population density and dramatic declines from recent Yellow Fever outbreaks. In March 2013, we organized an international workshop in Misiones to evaluate population status in Argentina and conduct a threat analysis. We developed population viability models using Vortex and Outbreak software packages. These tools allowed us to explore how several biological and demographic parameters of brown howlers, as well as factors related to Yellow Fever epidemiology, affect the probability of species extinction. The discussion among diverse specialists and analysis of model results identified Yellow Fever as the main threat to brown howler population persistence in Argentina. Our threat analysis, focused on the dynamics of Yellow Fever outbreaks and their impact on howler populations, led to the identification of gaps in knowledge that helped prioritize objectives and actions for the development of a Species Conservation Strategy in Argentina.; El mono aullador marrón (Alouatta guariba clamitans) es endémico del Bosque Atlántico de América del Sur, con una pequeña población que se extiende en la porción norte de la provincia de Misiones en el noreste de Argentina. En el año 2012, debido a su reducida distribución geográfica, su baja densidad poblacional y al dramático impacto de los recientes brotes de Fiebre Amarilla, la especie fue categorizada en Argentina como “en peligro crítico”. En el mes de marzo de 2013 organizamos un taller internacional en Misiones con el objetivo de evaluar el estado de la población de esta especie en Argentina y llevar a cabo un análisis de las principales amenazas para su conservación. Para alcanzar estos objetivos construimos modelos de viabilidad poblacional utilizando los programas Vortex y Outbreak. Los mismos nos permitieron explorar cómo varios parámetros biológicos y demográficos de la especie, así como diversos factores relacionados al impacto de la Fiebre Amarilla, influyen sobre la probabilidad de extinción de la especie. La discusión entre los distintos especialistas y el análisis de los resultados de los modelos identificaron a la Fiebre Amarilla como la principal amenaza para la subsistencia de esta población en Argentina. El análisis de las amenazas se centró en la dinámica de los brotes de Fiebre Amarilla y la severidad de su impacto sobre la población de esta especie, lo que permitió identificar huecos en el conocimiento que permitieron priorizar objetivos y acciones a llevar a cabo para el desarrollo de una estrategia de conservación para esta especie en Argentina.

Obesidad por índice de masa corporal y obesidad central en adolescentes de Comodoro Rivadavia, Patagonia Argentina; Obesity by BMI and central obesity in adolescents from Comodoro Rivadavia, Patagonia Argentina Ponce, Graciela M.; Quezada, Andrés O.; Rodríguez, María A; Boeri, Mónica P.; Soto, Mariana S.; Brites, Fernando Daniel Antecedentes: La prevalencia de obesidad infantil y adolescente resulta relevante ya que con frecuencia el sobrepeso a esa edad persistirá en la vida adulta. Objetivo: Determinar sobrepeso y obesidad en una población adolescente de Comodoro Rivadavia, Patagonia Argentina. Métodos: Se utilizaron las tablas propuestas para el índice de masa corporal (IMC) y la circunferencia de cintura (CC) por los siguientes tres grupos: International Obesity Taskforce (IOTF), Centers for Disease Control and Prevention (CDC) y la Organización Mundial de la Salud (OMS). Se evaluó el grado de concordancia en las definiciones, en relación a las tablas empleadas. Se estudiaron por muestreo no probabilístico y consecutivo, 402 voluntarios (279 mujeres y 123 varones) de edades comprendidas entre 12 y 16 ± 0,5 años. Con consentimiento escrito de los padres y asentimiento de los voluntarios, se midió peso, talla presión arterial y CC. Se calcularon percentiles del IMC y de la CC. Resultados: Al utilizar tanto las tablas IOTF como CDC más del 40 % de la población presentó sobrepeso u obesidad según el IMC. No se evidenciaron diferencias estadísticamente significativas al evaluar sobrepeso según sexo mientras que los varones presentaron mayores índices de obesidad con ambas definiciones (p<0,01). Cuando se empleó la CC (OMS, CDC), no se observaron diferencias según sexo (p>0,05). Conclusiones: La prevalencia de obesidad es elevada tanto al considerar percentiles tanto de IMC, como de CC. El grado de acuerdo de las definiciones es adecuado. Estos resultados aportan información regional inexistente hasta este momento y alertan sobre una situación que requiere una urgente intervención sanitaria.; Background: The prevalence of overweight and obesity in childhood and adolescence is important because it will frequently persist in adult life. Objective: To determine overweight and obesity in a group of adolescents from Comodoro Rivadavia, Argentine Patagonia through the use of body mass index (BMI) and waist circumference. Methods: Obesity Taskforce (IOTF), Centers for Disease Control and Prevention (CDC) and Word Health Organization (WHO) tables were used. The agreement degree in the definitions was evaluated in relation with the tables used. 402 volunteers were studied, aged between 12 to 16 years old ± 0.5. Written parental consent and assent of volunteers were obtained. Anthropometry, blood pressure were measured, andbody mass index and waist circumference´s percentile (Pc) were calculated. Results: Over 40 % of the adolescents were obese or overweight (BMI equal or major 95 or 85, respectively). There weren´t significant statistic difference between overweight and gender while the males showed majors obesity index with both definitions (p<0.01). There wasn’t significant statistical difference with gender with the use of circumference waist (WHO, CDC) (p>0.05). Conclusions: The prevalence of obesity is high with both BMI, as waist circumference percentiles. The degree agreement of the definition is adequate. These results contribute regional information that actually it is non-existent up to now and it alert about a situation that requires an urgent sanitary intervention.

Shifts in microbial community structure and function in light- and dark-grown biofilms driven by warming Romaní, Anna; Borrego, Carles M.; Diaz Villanueva, Veronica; Feixa, Anna; Gaush, Frederic; Ylla, Irene Biofilms are dynamic players in biogeochemical cycling in running waters and are subjected to environmental stressors like those provoked by climate change. We investigated whether a 2°C increase in flowing water would affect prokaryotic community composition and heterotrophic metabolic activities of biofilms grown under light or dark conditions. Neither light nor temperature treatments were relevant for selecting a specific bacterial community at initial phases (7-day-old biofilms), but both variables affected the composition and function of mature biofilms (28-day-old). In dark-grown biofilms, changes in the prokaryotic community composition due to warming were mainly related to rotifer grazing, but no significant changes were observed in functional fingerprints. In light-grown biofilms, warming also affected protozoan densities, but its effect on prokaryotic density and composition was less evident. In contrast, heterotrophic metabolic activities in light-grown biofilms under warming showed a decrease in the functional diversity towards a specialized use of several carbohydrates. Results suggest that prokaryotes are functionally redundant in dark biofilms but functionally plastic in light biofilms. The more complex and self-serving light-grown biofilm determines a more buffered response to temperature than dark-grown biofilms. Despite the moderate increase in temperature of only 2°C, warming conditions drive significant changes in freshwater biofilms, which responded by finely tuning a complex network of interactions among microbial populations within the biofilm matrix

Trophic ontogenetic shifts of the dragonfly Rhionaeschna variegata: the role of larvae as predators and prey in Andean wetland communities Jara, Fabian Gaston Body size strongly influences the type and strength of species interactions. Animals with complex life cycles, such as dragonflies, usually go through different stages that include a variation in body size and may involve shifts in their trophic position in the food web. This investigation analyzes the position of the dragonfly Rhionaeschna variegata in the food web according to its body size in Andean wetland communities of northwestern Patagonia (Argentina). The phenology of R. variegata larvae and their potential intraguild predators were studied in wetlands with different hydroperiods. Under controlled experimental conditions, feeding trials were performed to assess the effect of R. variegata on the survivorship of different types of prey. The effects of cannibalism and intraguild predation on the survivorship of the small larvae of R. variegata were investigated with and without alternative prey as well as different sympatric predators. The phenology of R. variegata and intraguild predators differed among wetlands. The feeding trials showed that R. variegata has a significant effect on the survivorship of invertebrate and vertebrate prey. Cannibalism increased with body size in odonate larvae. The survivorship of small and medium-sized larvae was mainly affected by the presence of larger predators such as belosmatids. The field and experimental data show that the effect of intraguild predation and cannibalism is affected by the cohort dynamics of R. variegata. Body size in R. variegata determines the strength of its interaction with other components of the community.

Adherence in a pavement rehabilitated with a polymeric grid used as interlayer Delbono, Héctor Luis; Giudice, Carlos Alberto A polymeric grid was placed between layers of a pavement with the aim of preventing the reflection of cracks from the base material to the upper layer. Results explain why the usual faults that occur in rehabilitated pavements: (i) chemical modifications of geosynthetic polypropylene determined by FTIR lead to changes in its melting point; (ii) the discontinuity or continuity of the interface observed by SEM depends on the application temperature of the asphalt mix and (iii) the adherence obtained in laboratory tests correlates perfectly with the quoted chemical modifications of geosynthetic polypropylene and the structure of interface in multilayer pavements.

El arte rupestre del nordeste de la Meseta de Somuncurá: caracterización inicial e integración regional (nordpatagonia, Argentina) Blanco, Rocío Vanesa; Miotti, Laura Lucia; Carden, Natalia Marina En este trabajo se presenta el análisis comparativo de tres localidades con arte rupestre asociadas a lagunas en el sector oriental de la meseta de Somuncurá: Laguna La Maciega, Laguna Azul y El Ganso. Esta información se inserta, posteriormente, en un contexto regional, considerando una amplia diversidad de sitios con manifestaciones rupestres ubicados sobre esta altiplanicie y en sus inmediaciones. Los resultados obtenidos en una escala mesorregional señalan una alta diversidad de motivos y técnicas que se acentúa en Laguna La Maciega. Esta diversidad, junto con el análisis de las pátinas, sugiere la posibilidad de usos recurrentes de las mencionadas cuencas. La evaluación de los contextos arqueológicos asociados al arte rupestre en Nordpatagonia permite enmarcar a la circulación de estas imágenes en la dinámica social del Holoceno tardío.

Novel evidence for the specific interaction between cholesterol and α-haemolysin of Escherichia coli Vazquez, Romina Florencia; Maté, Sabina María; Bakás, Laura S.; Fernández, Marisa Mariel; Malchiodi, Emilio Luis; Herlax, Vanesa Silvana Several toxins that interact with animal cells present some kind of interaction with cholesterol (Cho) or sphingomyelin. In the present work we demonstrate that alpha hemolysin of E. coli (HlyA) interacts directly with Chocholesterol, resulting in one of the first reported toxins secreted by Gram negative bacteria and the first reported member of the RTX toxin family that participates in the interaction with this sterol. We have recently reported that HlyA became associated with detergent-resistant membranes enriched in sphingomyelin and Chocholesterol; moreover, after Cho depletion, toxin oligomerization and hence hemolytic activity diminishes. Considering these results we studied the insertion process by monolayer technique, finding that HlyA insertion into membranes is favouredfavored in sphingomyelin and Chocholesterol-containing membranes. Taking into account this result, the direct interaction with either of the lipids was studied by lipid dot blot, lysis inhibition and surface plasmon resonance assays. Results demonstrated that there isit exists a direct interaction between Chocholesterol and HlyA that seems to favoursfavors a conformational state of the protein that allows the correct insertion into the membrane and further oligomerization to pore formation.

Applications of Stable Isotope Analysis in Zooarchaeology: An Introduction Zangrando, Atilio Francisco Javier; Tessone, Augusto; Ugan, A.; Gutierrez, Maria Amelia This special volume brings together works that present cases of studies that combine analysis of stable isotopes and zooarchaeology in different areas of Chile and Argentina, with special emphasis on the latter. These analyses were conducted in order to examine paleoecological conditions and interactions between humans and animal resources in different spatial and temporal contexts. In this introduction, we examine three ways in which stable isotopes have been applied in zooarcheology: (i) past animal-human relations, (ii) stable isotopes and zooarchaeology in conservation biology, and (iii) species biogeography, climate, and environment. The implications of the results of each of the papers in this volume stress that this type of study is a fruitful and promising line of research as it expands the thematic spectrum investigated, tests archaeological hypothesis, explores new lines of analysis, and enriches the interpretations about the past.

Synthesis and multi-technique characterization of nickel loaded MCM-41 as potential hydrogen-storage materials Carraro, Paola María; Elías, Verónica Rita; Garcia Blanco, Andres Alberto; Sapag, Manuel Karim; Moreno, Mario Sergio Jesus; Oliva, Marcos Iván; Eimer, Griselda Alejandra Ni/MCM-41 samples have been successfully prepared by wet impregnation method with different degrees of metal loading. Various techniques including X-ray diffraction, N2 adsorption?desorption, transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, electron microprobe analysis, UV?Vis diffuse reflectance spectra, infrared analysis, adsorption of pyridine coupled to infrared spectroscopy and hydrogen adsorption at 77 K at high and low pressure conditions were employed for the materials characterization. The Ni loading degree had a marked influence on the structural, chemical, acid and hydrogen storage properties of the samples. Thus, a low Ni loading favors the presence of highly dispersed Ni species responsible of the Lewis acidity. These species would promote hydrogen-favorable sites leading to a positive effect on the hydrogen storage capacity.

Another migid in the wall: natural history of the endemic and rare spider Calathotarsus simoni (Mygalomorphae: Migidae) from a hill slope in central Argentina Ferretti, Nelson Edgardo; Copperi, Maria Sofia; Schwerdt, Leonela Vanesa; Pompozzi, Gabriel Alejandro A population of Calathotarsus simoni Schiapelli and Gerschman (1975) was discovered on a hillside in the Ventania system, Argentina. Our objectives were to quantify burrow density, record burrow morphology and door characteristics and describe the micro-habitat. We counted 57 burrows and report a density of 0.01 burrows/m2. Aggregation indices suggest that burrows are aggregated under some area plots but more evenly distributed on others. The trapdoor is thick and rigid with bevelled edges connected to the entrance rim by a narrow articulated hinge. Two egg sacs from females were obtained and data on eggs and spiderlings are presented. We registered six burrows of an undetermined species of Actinopus. While a few specimens of Actinopus sp. were found inhabiting this hillside, the highest proportion of burrows belonged to C. simoni. Spider diversity on the hillside shows the predominance of Linyphiidae, Nemesiidae and Gnaphosidae. One juvenile of C. simoni was captured using pitfall traps.

Diversidad y endemismos de peces de la Cordillera Argentina. Amenazas Fernandez, Luis Alfredo Generalmente se usan indistintamente Diversidad o Biodirversidad como sinónimos de Riqueza (R). Cuando en realidad la mayoría de las veces sería más correcto hablar de Riqueza, que puede ser definida como el número de especies de fauna y flora presentes en un determinado espacio (ecosistema, bioto¬po, superficie o volumen) y en un determinado período de tiem¬po. Al contrario, la Diversidad toma en cuenta no sólo el número de especies diferentes (R) sino también su abundancia. Un Endemismo es un taxón que tiene una distribución restringida, es decir, que está sólo presente en un área determinada y que no se encuentra de forma natural en ninguna otra parte del mundo. Es un concepto estrictamente relativo ya que la distribución considerada debe ser menor que el área total considerada. Así el taxón bajo estudio (género, familia, etc.) puede ser endémico de una cordillera, una cuenca, un país o un continente dependiendo de la escala. Así Silvinichthys es un género ampliamente distribuido en la región oeste de la Argentina, pero a mayor escala es endémica de la Cordillera o de Argentina, ya que hasta el momento no fue hallada más allá de los Andes ni tampoco en otros países.

Genetic analysis of anthracnose resistance in Jalo Pintado 2 dry bean cultivar Frias, A. A. T.; Castro, S. A. L.; Nanami, D. S. Y.; Lacanallo, G. F.; Souza, M. C. M.; Galván, Marta Zulema; Gonçalves Vidigal, M. C. Anthracnose, caused by the fungus Colletotrichum lindemuthianum (Sacc. and Magnus) Briosi and Cavara, is one of the most widespread and economically important diseases of common bean (Phaseolus vulgaris L.) worldwide (Pastor-Corrales and Tu, 1989). Search for new sources of resistance have been the objective of many breeding programs, since genetic resistance is the most effective and environmentally friendly management strategy for the control of anthracnose disease in common bean. Therefore, this study aimed to investigate the genetic resistance to anthracnose in the Andean cultivar Jalo Pintado 2.

Evidence of low levels of genetic diversity for the Phytophthora austrocedrae population in Patagonia, Argentina Velez, Maria Laura; Coetzee, M. P. A.; Wingfield, M. J.; Rajchenberg, Mario; Greslebin, Alina Gabriela Phytophthora austrocedrae is a recently discovered pathogen that causes severe mortality of Austrocedrus chilensis in Patagonia. The high level of susceptibility of the host tree, together with the distribution pattern of the pathogen, have led to the hypothesis that P. austrocedrae was introduced into Argentina. The aim of this study was to assess the population structure of P. austrocedrae isolates from Argentina in order to gain an understanding of the origin and spread of the pathogen. Genetic diversity was determined based on amplified fragment length polymorphisms (AFLPs). In total, 48 isolates of P. austrocedrae were obtained from infected A. chilensis trees, representing the geographical range of the host. Four primer combinations were used for the AFLP analysis. Of the 332 scored bands, 12% were polymorphic. Gene diversity (h) ranged from 0·01 to 0·03; the Shannon index (I) ranged from 0·01 to 0·04. A high degree of genetic similarity was observed among the isolates (pairwise S values = 0·958–1; 0·993 ± 0·009, mean ± SD). A frequency histogram showed that most of the isolate pairs were identical. Principal coordinate analysis using three-dimensional plots did not group any of the isolates based on their geographical origin. The low genetic diversity (within and between sites) and absence of population structure linked to geographic origin, together with the aggressiveness of the pathogen and the disease progression pattern, suggest that P. austrocedrae might have been introduced into Argentina.

Creep dynamics of viscoelastic interfaces Jagla, Eduardo Alberto The movement of a purely elastic interface driven on a disordered energy potential is characterized by a depinning transition: when the pulling force σ is larger than some critical value o1 the system is in a flowing regime and moves at a finite velocity. On the other hand, if o < o1 the interface remains pinned and its velocity is zero. We show that in the case of a one-dimensional interface, the inclusion of viscoelastic relaxation produces the appearance of an intervening regime between the pinned and the flowing phases in a well-defined stress interval o0 < o < o1, in which the interface evolves through a sequence of avalanches that give rise to a creep process. As o - o0+ the creep velocity vanishes as a power law. As o < o0+ the creep velocity increases as a power law due to the increase of the typical size of the avalanches. The present observations may serve to improve the understanding of fatigue failure mechanisms.