La trama del polvo y del tiempo: el delito de homicido en Córdoba del Túcuman: siglo VXIII; The plot of dust and time: the crime of murder in Cordoba del Tucumán: XVIII century Aspell, Marcela La presente investigación, que es parte de un trabajo mayor sobre la muerte en la jurisdicción de Córdoba del Tucumán, analiza las formas de la muerte violenta, en un enclave de particulares condicio- nes socio-económicas, vigorosamente marcadas. Una ciudad medite- rránea, cruce de caminos y nudo de comunicaciones para los peregrinos que recorrían las rutas hacia Buenos Aires, Asunción, Santiago o Lima, alejada del teatro de las guerras, pero permanente frontera con el indio, cabecera del obispado, y sede de la Universidad que el 22 de agosto de 1791 incorpora los estudios regulares de Derecho, al crear- se la Cátedra de Instituta, circunstancia que contribuyó eficazmente a difundir el conocimiento y afianzar la práctica del derecho culto, para reemplazar una justicia de jueces legos, cuyo funcionamiento se em- peñaba en controlar la Justicia de Alzada.; This research, which is part of one larger work on death in the jurisdiction of Córdoba del Tucumán, analyzes forms of violent death in particular socio-economic conditions, vigorously marked. Córdoba was a Mediterranean city, crossroads and communications center for the pilgrims who traveled routes to Buenos Aires, Asunción, Santiago or Lima, far away from the theatre of war, but near the permanent border with the Indian, head of the bishopric, and seat of the University, which on 22 August 1791 incorporated regular law studies with the creation of the Chair of Instituta, circumstances that contributed effec- tively to disseminate the knowledge and strengthen the practice of the instituted law, to replace a the lay judges, whose work was controlled by the Justice of Appeal.

Chronic stress and its effects on adrenal cortex apoptosis in pregnant rats Bozzo, Aida Andrea; Soñez, Carlos Alberto; Monedero Cobeta, I.; Rolando, Alicia Nelida; Romanini, María Cristina; Cots, Debora Soledad; Lazarte, M. A.; Gauna, Hector Fernando; Mugnaini, M The model of chronic intermittent stress by immobilization during pregnancy may produce alterations in the mechanisms that maintain adrenal gland homeostasis. In earlier investigations using this model, signifi cant variations in plasma prolactin and corticosterone levels, and adrenal gland weights were observed. We hypothesized that chronic stress causes changes in apoptosis in the adrenal glands of pregnant rats. We identifi ed and quantifi ed apoptotic cells in the adrenal cortex and examined their ultrastructural characteristics using transmission electron microscopy. Adrenal glands of pregnant rats at gestation days 12, 17 and 21 were studied for control and experimental (stressed) rats. Immunolabelling techniques, stereological analysis and image quantifi cation of adrenal gland sections were combined to determine differences in apoptosis in the different cell populations of the adrenal cortex. The apoptotic index of the experimental rats showed a signifi cant reduction at gestation day 17, while at days 12 and 21 there were no differences from controls. Moreover, the apoptotic index of the reticular zones in control and experimental animals showed a signifi cant increase compared to the glomerular and fascicular zones at the three gestation times studied. Chronic stress by immobilization reduced the caspase-dependent apoptotic index at gestation day 17, which may be related to variations in plasma concentrations of estrogens and prolactin.

Rhizoremediation of phenol and chromium by the synergistic combination of a native bacterial strain and Brassica napus hairy roots Ontañon, Ornella Mailén; González, Paola Solange; Ambrosio, Laura Fernanda; Paisio, Cintia Elizabeth; Agostini, Elizabeth A bacterial strain resistant to phenol and Cr (VI) was isolated from an industrial polluted soil of Córdoba province (Argentina), which was identified as Pantoea sp. FC 1. This microorganism was able to use phenol as sole carbon source. In addition it was capable of reducing Cr (VI) to Cr (III) in mineral and nutrient media. The isolated strain exhibited some properties as plant-growth promoting bacterium (PGPB), such as production of Indole Acetic Acid (IAA) and synthesis of siderophores, as well as being capable of solubilizing inorganic phosphates. A rhizoremediation system using the association Pantoea sp. FC 1-Brassica napus hairy roots (HRs) was tested for phenol and Cr (VI) removal in a hydroponic system. Microbial inoculation improved both phenol removal and chromium accumulation efficiency by HRs, showing a significant increase in Cr (III) accumulation compared to non-inoculated HRs, exceeding 1000 mg kg−1. Cr (III) was detected in HR biomass and supernatants, suggesting a possible Cr (VI) reducing activity of B. napus HRs. Basic studies in plant model systems, such as HRs, provide additional useful information that could facilitate the transition of this technology into plants suitable for practical rhizoremediation applications.

What stories can the Frankia genomes tell us? Tisa, Louis S.; Beauchemin, Nicholas; Gtari, Maher; Sen, Arnab; Wall, Luis Gabriel Among the Actinobacteria, the genus Frankia is well known for its facultative lifestyle as a plant symbiont of dicotyledonous plants and as a free-living soil dweller. Frankia sp. strains are generally classified into one of four major phylogenetic groups that have distinctive plant host ranges. Our understanding of these bacteria has been greatly facilitated by the availability of the first three complete genome sequences, which suggested a correlation between genome size and plant host range. Since that first report, eight more Frankia genomes have been sequenced. Representatives from all four lineages have been sequenced to provide vital baseline information for genomic approaches toward understanding these novel bacteria. An overview of the Frankia genomes will be presented to stimulate discussion on the potential of these organisms and a greater understanding of their physiology and evolution.

(In)versiones de ciudad Ferrero, María Mercedes; Gallego, Ayelén Dominique La producción del espacio urbano se erige como cristalización histórica de las luchas por el poder y el acceso a los recursos. En él se materializan patrones de apropiación, habitabilidad, accesibilidad, exclusividad y fragmentación, como expresión de dichas tensiones y conflictividades. Durante el año 2011 se dio en la ciudad de Córdoba un debate mediatizado sobre la legitimidad de las obras públicas del gobierno provincial, la (in)existencia de licitaciones, la corrupción y el modelo de ciudad. En dicho contexto, alcanzó estado parlamentario en el Concejo Deliberante un documento denominado Bases para el Plan Director 2020 (PD), como primera iniciativa para delinear una política de estado que anticipe y oriente el proceso de transformación de la ciudad, proyectándola como polo de desarrollo económico, social y cultural del centro del país para el año 2020. Esta establece como objetivo fundamental la institucionalización de la metropolización y la densificación de dicha ciudad, así como su (re)conversión en un espacio estratégico de productividad y rentabilidad.

Anisotropy of pore size classes’ connectivity related to soil structure under no tillage Lozano, Luis Alberto; Soracco, Carlos Germán; Cornelis, Wim M.; Gabriels, Donald; Sarli, Guillermo Oliverio; Villarreal, Rafael No-tillage (NT) systems have been increasing during the last several decades. Development of a near-surface layer of laminar structure under NT has also been reported. The objectives of this work were to determine whether preferential connectivity of different pore size classes in two differently textured soils under NT exists and to propose a new index of pore connectivity based on water flux (Cw). The study was carried out at two sites in the Pampas Region of Argentina under long-term NT. Site 1 had a loamy A-horizon, and Site 2 had a sandy loam A-horizon. Undisturbed samples were extracted in vertical and horizontal directions within the first 8 cm of the soil. Saturated hydraulic conductivity (K s), near-saturated hydraulic conductivity (h: −50, −100, −200, −300, and −500 cm), pore size distribution from water retention curve, and total porosity were determined. The index of pore connectivity based on water flux, Cw, was developed as a ratio between K and pore volume for each pore size class. Site 1 showed laminar structure in the A-horizon, whereas Site 2 showed a blocky structure. We found a preferential connectivity in horizontal direction of macropores in Site 1. The index of pore connectivity was useful to assess the presence of preferential orientation of different pore size classes. In future studies, the connectivity of the different pore size classes should not be neglected.

Actualización del conocimiento de los roedores del Mioceno Tardío de la Mesopotamia argentina: aspectos sistemáticos, evolutivos y paleobiogeográficos; Update of the knowledge on the Late Miocene rodents from the Argentine Mesopotamia: systematic, evolutionary, and paleobiogeographic aspects Nasif, Norma; Candela, Adriana Magdalena; Rasia, Luciano Luis; Madozzo Jaén, María Carolina; Bonini, Ricardo Adolfo Los roedores registrados en el “Conglomerado osífero”, aflorante en la base de la Formación Ituzaingó (=“Mesopotamiense”, Mioceno Tardío, Edad Mamífero Huayqueriense), pertenecen al grupo de los caviomorfos. En esta unidad, éstos muestran una importante diversidad de especies, representantes de todas las superfamilias y casi todas las familias reconocidas en este infraorden. Presentan una notable variedad de patrones morfológicos, tales como rangos amplios de tamaño corporal y diferentes grados de complejidad dentaria e hipsodoncia. Ambos atributos, diversidad taxonómica y disparidad morfológica, le otorgan a las especies del “Mesopotamiense” una particular importancia para el entendimiento de aspectos evolutivos y biogeográficos en el contexto de la historia de los caviomorfos de América del Sur. A pesar de los avances recientes en la sistemática de estos roedores, particularmente de aquellos registrados en el “Mesopotamiense”, aún quedan por resolver numerosos aspectos referentes al número de especies y a sus afinidades filogenéticas. En este trabajo se actualiza el conocimiento sistemático de los Caviomorpha registrados en la Formación Ituzaingó (provincia de Entre Ríos, Argentina) y se proponen hipótesis preliminares acerca del significado biogeográfico y paleoambiental de algunas de las formas representadas en esta unidad.; Rodents recorded in the “Conglomerado osífero”, outcropping at the base of the Ituzaingó Formation (=“Mesopotamiense”, late Miocene, Huayquerian Land Mammals Age), are included in the Caviomorpha. Remains recovered in this unit show an important species diversity, encompassing all Caviomorph superfamilies and almost all the families recognized within the infraorder. Moreover, these rodents have a great variety of morphological patterns, such as wide body size ranges, and different degree of dental complexity and hypsodonty. Both attributes, taxonomic and morphological diversity, render Mesopotamian species important for the explanation of evolutionary and biogeographic aspects in the context of South American caviomorph history. In spite of the recent advances in the systematics of these rodents, in particular those from the “Mesopotamiense”, several aspects concerning the number of species and their phylogenetic affinities remain unresolved. In this contribution the systematic knowledge of Caviomorpha from the Ituzaingó Formation (Entre Ríos Province) is updated and preliminary hypotheses about the biogeographic and palaeoenvironmental significance of some of them are proposed.

Semblanzas Ictiológicas: Guillermo Martín Caille Lopez, Hugo Luis; Ponte Gomez, Justina A través de esta serie intentaremos conocer diferentes facetas personales de los integrantes de nuestra “comunidad”. El cuestionario, además de su principal objetivo, con sus respuestas quizás nos ayude a encontrar entre nosotros puntos en común que vayan más allá de nuestros temas de trabajo y sea un aporte a futuros estudios históricos. Esperamos que esta iniciativa pueda ser otro nexo entre los ictiólogos de la región, ya que consideramos que el resultado general trascendería nuestras fronteras.

Moquiniastrum (Gochnatieae, Asteraceae): disentangling the paraphyletic Gochnatia Sancho, Gisela; Funk, Vicki A.; Roque, Nádia The new genus Moquiniastrum, the result of recent phylogenetic analyses, is described. Although these analyses are based on cpDNA and nDNA, they also involve documentation of the distinctive morphological characters supporting this new genus. The recognition of Moquiniastrum is necessary to accurately reflect the relationships of the taxa found in the tribe Gochnatieae. Moquiniastrum includes twenty-one species that are usually gynodioecious and found mainly in Brazil but with some species elsewhere in South America. A description of Moquiniastrum, together with the corresponding new combinations, new lectotypifications of three names and one new neotypification is here provided.

Cost-benefit of feeding on anthropogenic organic matter: lipid changes in a detritivorous fish (Prochilodus lineatus) Speranza, Eric Demian; Tatone, Leandro Martín; Cappelletti, Natalia Elsa; Colombo, Juan Carlos The lipid composition of muscle and liver of detritivorous fish Prochilodus lineatus, settling particles and sediments from reference and polluted areas of the Paraná-Rio de la Plata basin were analyzed to evaluate the impact of feeding on contaminated detritus. Overall, muscular lipids were highly variable (14 ± 13 % wet mass, ww) and increased with body mass trough a rapid triglyceride accumulation [82 ± 7.9 % neutral lipids (NL) for fish weighing less than 1 kg to 99 ± 0.51 % NL for fish weighing more than 4 kg] with a parallel decrease of free fatty acid (13 ± 6.0 to 0.11 ± 0.23 % NL). Liver lipids were more uniform (6.0 ± 2.1 % ww) and were dominated by triglycerides (40 ± 21 % NL) and free fatty acids (34 ± 19 % NL). Compared with fish from reference areas in the North, polluted fish from Buenos Aires presented higher muscular lipid contents (24 ± 13 vs. 3.9 ± 3.1 % ww) and triglyceride abundance (98 ± 3.5 vs. 84 ± 9.7 % NL), and enlarged livers (Hepatosomatic index 1.4 ± 0.4 vs. 0.7 ± 0.2) enriched with esterified cholesterol (20 ± 9.1 vs. 11 ± 9.9 % NL). These differences were consistent with the higher proportions of lipids, enriched with free fatty acids and triglycerides, in stomach contents, settling particles and sediments from Buenos Aires relative to the North of the basin. The change in Prochilodus lineatus diet from organic-poor vegetal detritus in the north to polluted but abundant and fresh anthropogenic matter at Buenos Aires resulted in multiple alterations of lipid metabolism.

Limited Packing and Multiple Domination problems: Polynomial time reductions Leoni, Valeria Alejandra; Nasini, Graciela Leonor The Limited Packing and Multiple Domination problems in graphs have closely-related definitions and the same computational complexity on several graph classes. In this work we present two polynomial time reductions between them. Besides, we take into consideration generalized versions of these problems and obtain polynomial time reductions between each one and its generalized version.

On the first Chvátal closure of the set covering polyhedron related to circulant matrices Tolomei, Paola Beatriz; Torres, Luis Miguel We study the set covering polyhedron related to circulant matrices. In particular, our goal is to characterize the first Chvátal closure of the usual fractional relaxation. We present a family of valid inequalities that generalizes the family of minor inequalities previously reported in the literature. This family includes new facet-defining inequalities for the set covering polyhedron.

Forbidden subgraphs and the König–Egerváry property Bonomo, Flavia; Dourado, Mitre C.; Duran, Guillermo Alfredo; Faria, Luerbio; Grippo, Luciano Norberto; Safe, Martin Dario The matching number of a graph is the maximum size of a set of vertex-disjoint edges. The transversal number is the minimum number of vertices needed to meet every edge. A graph has the König-Egerváry property if its matching number equals its transversal number. Lovász proved a characterization of graphs having the König-Egerváry property by means of forbidden subgraphs within graphs with a perfect matching. Korach, Nguyen, and Peis proposed an extension of Lovász´s result to a characterization of all graphs having the König-Egerváry property in terms of forbidden configurations (which are certain arrangements of a subgraph and a maximum matching). In this work, we prove a characterization of graphs having the König-Egerváry property by means of forbidden subgraphs which is a strengthened version of the characterization by Korach et al. Using our characterization of graphs with the König-Egerváry property, we also prove a forbidden subgraph characterization for the class of edge-perfect graphs.

When and why noise correlations are important in neural decoding Eyherabide, Hugo Gabriel; Samengo, Ines Information may be encoded both in the individual activity of neurons and in the correlations between their activities. Understanding whether knowledge of noise correlations is required to decode all the encoded information is fundamental for constructing computational models, brain–machine interfaces, and neuroprosthetics. If correlations can be ignored with tolerable losses of information, the readout of neural signals is simplified dramatically. To that end, previous studies have constructed decoders assuming that neurons fire independently and then derived bounds for the information that is lost. However, here we show that previous bounds were not tight and overestimated the importance of noise correlations. In this study, we quantify the exact loss of information induced by ignoring noise correlations and show why previous estimations were not tight. Further, by studying the elementary parts of the decoding process, we determine when and why information is lost on a single-response basis. We introduce the minimum decoding error to assess the distinctive role of noise correlations under natural conditions. We conclude that all of the encoded information can be decoded without knowledge of noise correlations in many more situations than previously thought.

Subjetividad y política: tres lecturas discursivas del sujeto político Dagatti, Mariano Jesús Esta presentación tiene por objetivo realizar un comentario de investigaciones discursivas en torno a la cuestión de la subjetividad política, con el fin de colaborar en el diseño de un marco teórico para estudiar la conformación de identidades en el discurso político. El texto propone, así, un recorrido por los aportes de la teoría de los discursos sociales de E. Verón, de la teoría de la hegemonía de E. Laclau y de los trabajos de D. Maingueneau sobre la noción de ethos. Perspectivas disímiles surgidas en el contexto del giro discursivo, estos estudios parten de una crítica del sujeto como fuente del sentido y de la determinación como característica de la comunicación. El estado de la cuestión permite subrayar la importancia de estos desarrollos para investigar los procesos de credibilidad e identificación que atraviesan el juego político: ruptura de la linealidad, disimilitud de las lógicas de funcionamiento, circulación semiótica y articulación hegemónica, imágenes de sí e imágenes del cuerpo social, instituciones, estilos y colectivos son algunas de las categorías involucradas en esta ponencia. Como conclusión, mencionamos el peso decisivo de los liderazgos en la interfaz entre las lógicas institucionales e individuales. Esta afirmación se contrapone a la condena que éstos reciben por parte de quienes entreven en la presencia de un líder fuerte un atentado a la verdadera democracia.; La presentazione è destinata a fare un commento di ricerca discorsiva intorno alla questione della soggettività politica. L'obiettivo è quello di contribuire a progettare un quadro teorico per studiare la formazione di identità nel discorso politico. Si propone, pertanto, una lettura dei contributi della teoria del discorso sociale di E. Veron, della teoria dell’egemonia di E. Laclau e della ricerca di D. Maingueneau sul concetto di ethos. Prospettive dissimili che sorgono nel contesto della “svolta discorsiva”, questi studi si basano su una revisione dell soggeto come fonte di significato e della determinazione comme caratteristica centrale della comunicazione. Lo stato di cose serve a sottolineare l'importanza di questi sviluppi per studiare i processi di credibilità e di identificazione che abbracciano il gioco politico: rottura della linearità, dissimilarità delle logiche di funzionamento, circolazione semiotica e articolazione egemonica, ethos e immagini di corpo sociale, le istituzioni, gli stili e collettivi sono alcune delle categorie coinvolte in questo lavoro. In conclusione, citiamo il peso determinante della leadership nella interfaccia tra logiche individuali e istituzionali. Questa affermazione è in contrasto con la convinzione che essi ricevono da quelli intravisto in presenza di un forte leader di un tentativo di vera democrazia.; This paper aims to conduct a review of discourse research around the issue of political subjectivity. The goal is to help design a theoretical framework for studying the formation of identity in political discourse. It proposes, therefore, a journey through the contributions of social discourse theory of E. Verón, hegemony theory of E. Laclau and the work of D. Maingueneau on the notion of ethos. Dissimilar perspectives arising in the context of the discursive turn, these studies are based on a review of the subject as a source of meaning and of the determination as a central feature of communication. The state of the art serves to underline the importance of these developments to investigate the credibility and identification processes spanning the political game: breakdown of linearity, dissimilarity of the operation logic, semiotics circulation and hegemonic articulation, self-images and social imaginary, institutions, styles and collective are some of the categories involved in this paper. In conclusion, we mention the decisive weight of leadership at the interface between individual and institutional logics. This statement is contrary to the idea from those who glimpsed in the presence of a strong leader an attempt to true democracy.

Invariancia de Medidas de la prueba de figuras del Test de Pensamiento Creativo de Torrance según la edad: Un estudio en niños y adolescentes de habla hispana; Measurement Invariance of Torrance Test of Creative Thinking Figural Scores across Age: A study in Spanish-Speaking Children and Adolescents.; Invariância de Medidas da prova de figuras do Teste de Pensamento Criativo de Torrance segundo a idade: Um estudo em crianças e adolescentes de língua espanhola. Krumm, Gabriela Liliana; Arán Filippetti, Vanessa; Lemos, Viviana Noemí; Aranguren, María; Vargas Rubilar, Jael Alejandra En base a un estudio previo que indica que el constructo creatividad operacionalizado con el Test de Pensamiento Creativo de Torrance (TTCT) de Figuras está compuesto por dos factores Innovación y Adaptación, en niños de habla hispana (Krumm, Lemos & Arán Filippetti, en prensa), el objetivo de este trabajo fue comprobar si esta estructura es invariante según la edad de los sujetos. Se trabajó con una muestra de 652 niños y adolescentes de 9 a 17 años de ambos sexos de habla hispana divididos en tres grupos: (a) 9-10 años, (b) 11-13 años y (c) 16-17 años. El Análisis Factorial Confirmatorio (AFC) mostró que la estructura del TTCT está integrada por dos factores correlacionados, Innovación y Adaptación en las tres muestras de estudio. Además, los resultados del AFC multigrupo revelaron que la estructura de dos factores es invariante (configural y métrica) a través del edad, lo que significa que los niños y adolescentes conceptualizan el constructo Creatividad de la misma manera. Finalmente, el análisis multivariado de varianza (MANOVA) reveló un efecto significativo de la edad en todas las subescalas. Estos datos muestran la importancia de la edad como un factor a tener en cuenta en el estudio del potencial creativo a través del TTCT-Figuras.; On the basis of a previous study carried out with Spanish-speaking children which indicates that the Creativity construct, operationalized by means of the Torrance Tests of Creative Thinking (TTCT)-Figural, consists of two factors –Innovation and Adaptation– (Krumm, Lemos & Arán Filippetti, in press), the objective of the present work was to prove whether this structure is invariant across age. A sample of 652 Spanish-speaking children and adolescents aged 9-17 years of both sexes was tested. It was in turn divided into three age groups: (a) 9-10, (b) 11-13 and (c) 16 -17 years. Confirmatory Factor Analysis (CFA) showed that in each group of the sample, the structure of the TTCT is composed of two correlated factors, namely Innovation and Adaptation. In addition, Multigroup CFA demonstrated that the two-factor solution was actually invariant (configural and metric) across age, meaning that children and adolescents equally conceptualize the Creativity construct. Finally, MANOVA showed a significant age effect on every subscale. These data suggest the relevance of considering the age factor when assessing the creative potential through the TTCT-Figural.

Sistema de control para el almacenamiento intermedio de gasolina natural Oteiza, Paola Patricia; Rodriguez, Diego Alejandro; Brignole, Nelida Beatriz En Rodríguez et al., Ind Eng Chem Res., 52 (25), 8579−8588 (2013) se desarrolló un paquete general con el fin de encontrar una óptima red de cañerías para el transporte de gasolina natural proveniente de yacimientos gasíferos. Con esta herramienta, se analizó la distribución de líneas de transporte para yacimientos que se encuentran en la provincia de Santa Cruz (Argentina) y se localizaron los nodos concentradores. En estos nodos se proyecta almacenar la gasolina natural. Entonces, se desea controlar en forma óptima estos tanques con el objetivo de garantizar el suministro a la planta de procesamiento. Por lo tanto, en este trabajo analizamos la respuesta dinámica del sistema y, como primera etapa del estudio, optimizamos conjuntamente mediante Algoritmos Genéticos los parámetros de un controlador Proporcional-Integral-Derivativo y otro Proporcional-Integral de forma desacoplada.

Ordovician chitinozoans and marine phytoplankton of the Central Andean Basin, northwestern Argentina: A biostratigraphic and paleobiogeographic approach de la Puente, Graciela Susana; Rubinstein, Claudia Viviana Ordovician deposits from the Central Andean Basin cover a vast region with thick exposed sequences in several areas, including the Sierras Subandinas, Cordillera Oriental and Puna geological provinces of northwestern Argentina. This basin was situated along the active margin of a Paleozoic foreland basin in western Gondwana. Continuous sedimentation occurred in different paleoenvironments from east to west: marginal marine settings with estuarine and deltaic deposits (Sierras Subandinas), shallow marine shelf environments with large clastic deposits in the central part (Cordillera Oriental–eastern Puna), and deep marine deposits with volcaniclastic supplies (western Puna). Limited biostratigraphic and chronostratigraphic data from these sequences are known from graptolites, conodonts and trilobites, and more recently also from palynomorphs. An analysis of Ordovician sections from the different sedimentological settings of northwestern Argentina produced 60 chitinozoan-bearing samples from which 19 genera and 45 species have been recorded. Four chitinozoan assemblages were observed in the Lower Ordovician from northwestern Argentina. Correlations with other fossil groups provide independent biostratigraphic control. A stratigraphic range chart of selected acritarch taxa throughout the Ordovician of the Central Andean Basin is developed and biostratigrapic or potential biostratigraphic markers for the basin are proposed. In northwestern Argentina, Late Ordovician chitinozoan assemblages display affinities with Polar to Subpolar faunas.

Design and performance of a compact subthermal neutron source for an Electron Linear Accelerator Tartaglione, Aureliano; Galván Josa, Víctor Martín; Dawidowski, Javier; Cantargi, Florencia; Blostein, Juan Jeronimo We present the design, construction and performance of a compact subthermal neutron source to be operated at the Bariloche Electron LINAC. The design was based on the premise of keeping the moderator temperature stable at 77 K for at least seven hours without refilling liquid nitrogen. Two moderator materials in semi-cylindrical geometry were studied: polyethylene and mesitylene. The effective moderator volumes were optimized by Monte Carlo simulations. Experimental data and calculations corresponding to the neutron production as a function of the neutron energy for those materials at room temperature and at 77 K were compared. We observed that the rate of subthermal neutrons, compared to epithermal neutrons, increases up to five times for both moderators when they are cooled down.

Applying Cost-distance analysis for forest disease risk mapping: Phytophthora austrocedrae as an example la Manna, Ludmila Andrea; Greslebin, Alina Gabriela; Matteucci, Silvia Diana Cost-distance model analyzes the relative difficulty in reaching each spot of the landscape for the object or species under study. It calculates the effective distance, which is the Euclidian distance modified by the friction to movement through different landscape elements. This work deals with the application of cost-distance analysis in forest pathology, considering Austrocedrus chilensis root rot caused by Phytophthora austrocedrae as an example. In this case, cost-distance analysis was used to determine the relative difficulty for the pathogen to reach healthy forest patches from the patches that are presently diseased. Friction values were assigned on the basis of abiotic conditions, biological characteristics of the pathogen and host presence. Since cattle may be a vehicle for Phytophthora dispersion, three hypothetical situations of ranching were considered. Cost-distance application resulted useful to define minimum risk areas for conservation purposes. In the study case, minimum risk area strongly varied in response to cattle presence. This study provided valuable information for A. chilensis disease management and showed one of the broad applications of cost-distance analysis in forestry.