Quantifying higher-order correlations in a neuronal pool Montangie, Lisandro; Montani, Fernando Fabián Recent experiments involving a relatively large population of neurons have shown a very significant amount of higher-order correlations. However, little is known of how these affect the integration and firing behavior of a population of neurons beyond the second order statistics. To investigate how higher-order inputs statistics can shape beyond pairwise spike correlations and affect information coding in the brain, we consider a neuronal pool where each neuron fires stochastically. We develop a simple mathematically tractable model that makes it feasible to account for higher-order spike correlations in a neuronal pool with highly interconnected common inputs beyond second order statistics. In our model, correlations between neurons appear from q-Gaussian inputs into threshold neurons. The approach constitutes the natural extension of the Dichotomized Gaussian model, where the inputs to the model are just Gaussian distributed and therefore have no input interactions beyond second order. We obtain an exact analytical expression for the joint distribution of firing, quantifying the degree of higher-order spike correlations, truly emphasizing the functional aspects of higher-order statistics, as we account for beyond second order inputs correlations seen by each neuron within the pool. We determine how higher-order correlations depend on the interaction structure of the input, showing that the joint distribution of firing is skewed as the parameter q increases inducing larger excursions of synchronized spikes. We show how input nonlinearities can shape higher-order correlations and enhance coding performance by neural populations.

La familia Cactaceae en Argentina: patrones de diversidad y prioridades políticas para su conservación; The Cactaceae family in Argentina: diversity patterns and political priorities for their conservation Ortega Baes, Francisco Pablo; Godinez Álvarez, Héctor; Sajama, Modesto Jesus; Gorostiague, Pablo; Sühring, Silvia Susana; Galíndez, Guadalupe; Bravo, Silvia Alejandra; Lopez Spahr, Diego; Alonso Pedano, Mariana Inés; Lindow López, Lucía Teresa; Barrionuevo, Andrea Mariel; Sosa, Cecilia Ines; Curti, Ramiro Nestor; Juárez, Alejandra En este trabajo se utilizó la riqueza de especies y el endemismo de las especies de cactáceas argentinas para seleccionar las provincias con la mayor prioridad para la conservación de esta familia de plantas en el país. Además, se evaluó el papel de la diversidad de cactáceas como sustitutos de la diversidad de plantas dicotiledóneas de Argentina. La riqueza de especies (número de especies) y el endemismo (número de especies endémicas) fueron determinadas para cada una de las 24 provincias de Argentina. Un total de 15 provincias fueron seleccionadas como prioritarias con base en todas las especies de cactáceas y 14 con base en las especies endémicas. La provincia de Salta presenta la mayor riqueza de especies y endemismo. Las especies endémicas son un buen sustituto de la diversidad de cactáceas. De igual manera, las cactáceas son un buen sustituto de la diversidad de las plantas dicotiledóneas.; The Cactaceae family in Argentina: diversity patterns and political priorities for their conservation. In this paper we used species richness and endemism of Argentine cacti to select those provinces with highest priority for the conservation of this plant family in the country. The role of cactus diversity as a surrogate for dicot diversity was further analyzed. Species richness (number of species) and endemism (number of endemic species) were determined for each of the 24 provinces of Argentina. Fifteen provinces were selected as priority based on the number of species and 14 provinces were selected based on the number of endemic species. Salta province presents the highest species richness and endemism. Endemic species are a good surrogate for cactus diversity. Similarly, cactus diversity is a good surrogate for dicot diversity.

Calix[4]arene amine modified silica: From fundamentals to new recyclable materials for the removal of chlorophenoxy acids from water Danil De Namor, Angela F.; Zvietcovich Guerra, Jorge A.; Villanueva Salas, Jose A.; Piro, Oscar Enrique; Webb, Oliver A.; El Gamouz, Abdelaziz; Hamdan, Weam Abou; Castellano, Eduardo E. Two molecular receptors based on calix[4]arenes and their interaction with chlorophenoxy acid herbicides in solution and in the solid state have been investigated. From 1H NMR studies it is shown that the conformational changes of the receptor are directly related to the acid strength of the herbicide. Conductance data show that the interaction takes place through a proton transfer reaction from the herbicide to the receptor. This is also reflected in the solid state (X-ray crystallography). Based on these fundamental studies, these receptors were immobilised by grafting them into a silica based solid support. The extracting properties of calix[4]arene modified silica for these pollutants were investigated as a function of the pH of the aqueous solution and the capacities of these materials to remove these pollutants are reported. Titration calorimetry is for the first time explored to determine the factors (kinetics, mass/solution ratio and temperature) contributing to the optimal removal of herbicides from water. These materials can be easily recycled via a pH switching mechanism. After several recycling processes the extraction capacity of these materials remains at the level of 80-90% of the original value.

Palaeoenvironmental scenarios and lithic technology of the first human occupations in the Argentine Dry Puna Hoguin, Rodolphe; Oxman, Brenda The aim of this research is to contribute to the discussion of environmental scenarios and evaluate in this context lithic technical strategies developed by hunter-gatherer groups during the process of settlement of the area. The Andean paleoenvironmental knowledge supports the view that during the early Holocene (10,500-8000 14CBP, uncal.) the environmental conditions were more humid than at present, which would have produced both an extension of wetlands and an expansion of Andean grassland. However, the results of pollen analysis in this locality show that these changes were not synchronous. Certain localities may have retained humid conditions ca. 700014CB.P according to the Pastos Chicos record and 760014CB.P in the Lapao record. Thus, the reduction of the distance between the productive patches would have favored a strategy of highly mobile small groups of hunter-gatherers, allowing the supply of raw materials from long distances, and favoring individual learning, a flexible operational chain, and low technical investment. The Early Holocene is very heterogeneous with numerous environmental and technological changes.

Is sensory-specific satiety for a bitter-sweet infusion modulated by context? Garcia Burgos, David; Secchiari, Florencia; Calviño, Amalia Mirta The sensory-affective attributes of beverages have an important influence on a given intake and successive consumptions because of sensory-specific satiety (SSS; defined as a decrease in pleasantness ratings of a food eaten relative to uneaten foods). No studies have, however, investigated how multiple sessions of SSS for familiar drinks over a period of several days up to a week may change their pleasantness and how these hedonic-related judgments are affected by the context during SSS testing. With twenty-six participants, the present study explored the medium lasting and contextual effects of repeated SSS sessions for a bitter-sweet infusion on olfactory and flavour pleasantness over the course of three exposures in either a laboratory or a cafeteria setting. The results showed olfactory and flavour SSS for the infusion following each consumption in both the artificial and the natural setting. More interestingly, despite the failure to detect medium-term SSS (i.e., a greater decrease in pleasantness ratings of a food eaten relative to uneaten foods after repeated SSS sessions over several days as compared to the first SSS session), a contextual modulation of olfactory SSS was observed with a lesser overall magnitude in the cafeteria compared to the laboratory setting. To the best of our knowledge, the impact of eating location on the development of satiation and the differential contextual sensitivity of SSS for orthonasal odours and flavours has not been reported previously. The implications of potential environmental control of SSS are considered in this study.

Género y cuidado: Apuntes y evidencia empírica para un análisis preliminar Golovanevsky, Laura Andrea Si bien la necesidad de la reproducción de la vida –en todas sus dimensiones- existe desde el momento en que hay vida humana, la separación entre una esfera productiva (pública) y una esfera reproductiva (privada) se da específicamente a partir del cambio en el orden económico. En ese momento se cristaliza la división entre trabajo productivo (a cambio de un salario) y trabajo reproductivo (sin remuneración), expresada también en términos de división sexual. Serán las mujeres las encargadas de la reproducción biológica, social y de la fuerza de trabajo. Con el tiempo, la mujer logró mayor acceso, tanto a la educación como al mercado laboral. Si hombres y mujeres trabajan en el ámbito extra-doméstico por igual, ¿cómo se organizan las tareas reproductivas que son indispensables para la vida cotidiana? ¿Qué ocurre con las tareas de cuidado que tradicionalmente desempeñó la mujer? En relación a estos interrogantes se desarrolla en el trabajo una discusión acerca de la noción de cuidado y de la organización social del mismo, incluyendo algunos resultados empíricos obtenidos mediante el procesamiento de la Encuesta sobre Trabajo No Remunerado y Uso del Tiempo llevada a cabo en Argentina durante el tercer trimestre de 2013.; Though the need of reproduction of life - in all its dimensions - exists from the moment in which human life exists, the separation between a productive (public) sphere and a reproductive (private) one appeared when a change in the economic order took place. At that time the division between productive work (in exchange for a salary) and reproductive work (without remuneration) crystallizes and is expressed also in terms of sexual division. Women will be the in charge of the biological, social and working force reproduction. When time passed women achieved major access, both to education and labor market. If men and women are employed at the extra-domestic area equally, how are the reproductive tasks indispensable for the daily life organized? What does happen with the tasks of care that were traditionally performed by women? Related to these questions the paper develops a discussion about the notion of care and of its social organization, including some empirical results obtained by processing the Survey on Not Remunerated Work and Use of Time carried out in Argentina during the third quarter of 2013.

A MASH zone revealed: The mafic complex of the Sierra Valle Fértil Walker, Barry A.; Bergantz, George W.; Otamendi, Juan Enrique; Ducea, Mihai N.; Cristofolini, Eber Ariel The Sierra Valle Fértil Complex of west-central Argentina represents a section of the Ordovician (~470 Ma) Famatinian arc and exposes a continuous, tilted crustal arc section ranging in depth from ~12 to 32 km (~4-8 kbar pressure). This arc section exposes the complete compositional architecture from ultramafic and mafic rocks to upper crustal granodiorites. Field and compositional data are presented to document the deep (~6-8 kbar) mafic complex of the Sierra Valle Fértil. The mafic complex is composed of many tens to hundreds of plutonic cumulate bodies in a complex and non-regular arrangement. There is no simple compositional, kinematic or age relationship between neighboring plutons throughout the section, as expressed by cumulate compositions, emplacement horizon, size, composition, texture or style of contact. Amphibole gabbronorites and mafic tonalites dominate, but norites, amphibole websterites, troctolites and minor anorthosites are present. Amphibole is common but always as a replacement phase, and is never observed undergoing subsequent dehydration melting. Hence there is no evidence that voluminous tonalites were produced by dehydration melting of mafic precursors. A field-based, cumulate-removal fractionation model is presented that produces the observed compositional variations in five steps. Isotopic compositions of Sr and Nd deviate significantly from primitive mantle values, indicating a crustal contribution; however, this hybridization appears to have played a minor role in the major element evolution of the mafic complex. We interpret this isotopic and elemental decoupling as a byproduct of prolonged, punctuated MASH (melting, assimilation, storage, homogenization) processes in the lower crust. Isotopes may be the only residual evidence of assimilation within the mafic zone. This requires that melt removal from the cumulates was extraordinarily efficient.

Dogmática y seguridad jurídica Peralta, José Milton Suele afirmarse que la dogmática penal, especialmente la que se ocupa de la teoría del delito, ayuda a mejorar las decisiones judiciales. En este texto voy a distinguir tres sentidos en lo que esto pretende ser cierto: que contribuye a su previsibilidad, corrección y coherencia. Mostraré que la ambición de previsibilidad, además de ser dudosa desde un punto de vista empírico, es incompatible con la búsqueda de decisiones correctas. Ambas pretensiones se dirigen en sentido opuesto y la dogmática penal se ocupa, en realidad, de la segunda y no de la primera. De todos modos, y más allá del valor intrínseco que tiene la búsqueda de decisiones judiciales correctas, la dogmática sí aporta a la coherencia. Esta es, sin embargo, una virtud individual y temporal que tampoco sirve para la seguridad jurídica en el sentido en que se suele pregonar.

Estrategia de detección de fallas de circuito abierto en semiconductores de convertidores CC-CC aislados Airabella, Andres Miguel; Oggier, German Gustavo; Piris Botalla, Laureano Enrique; Falco, Cristian Ariel; García, Guillermo Oscar En este trabajo se analiza la operación de un convertidor CC-CC cuando uno de los semiconductores de potencia presenta una condición de falla de circuito abierto. Se propone una nueva estrategia de diagnóstico de falla, la cual consiste en medir la caída de tensión a bornes de cada uno de los semiconductores de potencia utilizando la información disponible en los circuitos de activación. La tensión medida se compara con un valor de referencia para determinar si un semiconductor presenta una condición de circuito abierto. Esta estrategia tiene la ventaja de que puede llevarse a cabo sin incluir sensores adicionales. Se incluyen resultados experimentales para validar la teoría.

La cooperación Sur-Sur en el Siglo XXI: Reflexiones desde América Latina Lechini, Gladys Teresita; Morasso, Carla La primera década del siglo XXI mostró un proceso de transformaciones en el sistema internacional donde actores emergentes ganaron protagonismo, impulsando una nueva etapa que permitió el resurgimiento de la cooperación Sur-Sur, la cual había sido considerada impropia y fue olvidada en los noventa. La región latinoamericana no fue ajena a estas vicisitudes y así como colocó en el olvido la cuestión a finales del siglo pasado, se convirtió en una activa participante en el presente. Es por ello que este trabajo se propone examinar el camino y los resultados de la cooperación Sur-Sur en América Latina en esta nueva fase de su re-edición. Para ello se aborda la cooperación en los foros multilaterales regionales y la cooperación internacional al desarrollo, las cuales contribuyeron a crear un ámbito propicio para la generación de contactos económico-comerciales. Finalmente a modo de balance, se explicitan algunos desafíos a los cuales se enfrentan los países del Sur en esta segunda década.

El problema de la equidad en las universidades del conurbano bonaerense en Argentina: un análisis de políticas institucionales para favorecer la retención; The Problem of Equity in Universities in Greater Buenos Aires, Argentina: An Analysis of Institutional Policies to Favor School Attendance Arias, Maria Fernanda; Mihal, Ivana Julieta; Lastra, Karina Fabiana; Gorostiaga, Jorge Manuel Este artículo analiza las políticas institucionales de cuatro universidades del conurbano bonaerense en Argentina, tendientes a procurar una mayor equidad en el ingreso y la retención de los alumnos de estratos sociales bajos. Como se observa en todo el sistema universitario argentino, la gratuidad y el ingreso relativamente irrestricto no aseguran la equidad, y los alumnos provenientes de los estratos socioeconómicos más bajos de la población representan un número exiguo. El caso de estudio es el de las universidades del conurbano bonaerense, región caracterizada por concentrar un gran porcentaje de población con altas tasas de necesidades básicas insatisfechas. El artículo analiza las perspectivas de docentes y coordinadores de los cursos de ingreso y del primer año de algunas carreras acerca de cómo se han implementado las políticas institucionales en las cuatro universidades y cuáles pueden ser los condicionantes del mantenimiento de la inequidad.; This article analyzes the institutional policies of four universities in Greater Buenos Aires, Argentina, that have favored greater equity in the enrollment and attendance of students from lower social strata. As observed throughout the Argentine university system, free tuition and relatively unrestricted acceptance do not ensure equity, and students from the population's lower socioeconomic strata are not numerous. The case under study involves universities in Greater Buenos Aires, a region characterized by its concentration of a high percentage of the population with high rates of unsatisfied basic needs. The article analyzes the perspectives of the teachers and coordinators of new student orientation and the first year of some majors, in terms of the implementation of institutional policies in the four universities and the possible causes of remaining inequity.

Pensar y sentir las diferencias: Cartas entre la amistad, la incomodidad y el sinsentido Bárcena, Fernando; Skliar, Carlos Bernardo A través de un intercambio epistolar los autores de este texto se preguntan por algunas palabras de orden en los territorios de la filosofía de la educación: igualdad, diversidad, diferencia. La pregunta por aquello que nombra, pero sobre todo la pregunta por aquello que habita en el lenguaje, en la escritura y la lectura cuando nombramos, se hace presente en el artículo de un modo crudo, desnudo. La conversación aquí planteada es, también, una forma de comprender la conversación en la filosofía y la educación: palabras que buscan conmover, pero además hacer sentir y pensar lo Mismo y lo Otro.; Through an exchange of letters the authors of this text ask for some words of order in the territories of the philosophy of education: equality, diversity, difference. The question of what names, but especially the question of what living in language, writing and reading when named, is present in the article in a raw, naked way. This count of conversation is also a way to understand the conversation in philosophy and education: words producing affect, but also trying to feel and think about the Same and about the Other.

Los poros del exilio Hochman, Mariano Nicolás Osvaldo Soriano (1943-1977), escritor y periodista argentino, se exilió a mediados de la década del ?70. Su experiencia en Bélgica y Francia, entre 1976 y 1984, fue fundamental para la escritura de sus novelas, en las que el tema del exilio aparece siempre de un modo sutil, un poco velado y aparentemente secundario, pero que muchas veces funciona como un eje que atraviesa las historias que narra en sus ficciones. En este artículo proponemos un análisis que se enfoca en cómo Soriano transmite al lector una sumatoria de vivencias, tanto en el extranjero como en el retorno a la patria. Un mundo en el que los personajes, que se mueven entre la risa y el grotesco, entre la aventura y heroísmos más bien patéticos, se hallan en una tensión permanente con respecto a su vínculo con el Estado, lo que los lleva a estar desarraigados aun dentro de su propia tierra.

Desde la cordillera al atlántico y desde los hidrocarburos policíclicos a los organométalicos Podestá, Julio Cesar Dentro de mis prioridades nunca estuvo escribir mis memorias. Por ello, cuando me solicitaron la redacción de una reseña autobiográfica necesité un cierto tiempo para analizar la propuesta. Venciendo mi innato perfil bajo y mi sentido autocrítico, consideré interesante ponerme a reflexionar y recordar algunos hitos de mi vida. Así que dejé de pensar en la actualidad y en el futuro, y volví hacia atrás tratando de recordar aquellos hechos que me impresionaron principalmente durante mi niñez y juventud, ya que los posteriores están más cercanos y frescos. En esta reseña incluyo exclusivamente hechos positivos y demostrables. Los negativos me los guardo para poder hacer el balance de mi vida, esperando que al hacerlo el resultado sea que mis aciertos superaron mis errores. El título de la reseña está relacionado, como se verá más adelante, con el recorrido geográfico de mi vida y luego con el inicio y final de mi vida científico-académica. Estoy de acuerdo con los poetas en que los caminos de la vida no son como los imaginamos y que en realidad los hacemos al andar. Al menos en mi caso, hasta aproximadamente los veinte años los caminos fueron marcados por los traslados de mi padre a lo largo y ancho del país. Luego sí, fueron mis decisiones las que me llevaron a construir el camino en cuya fase final me encuentro actualmente.

Reproductive ecology of coypu (Myocastor coypus Molina, 1782) in the Middle Delta of the Paraná River, Argentina; Ecología reproductiva do coipo (Myocastor coypus) no Delta Meio do Río Paraná (Entre Ríos. Argentina) Courtalon, Paula; Bó, Roberto Fabián; Spina, F.; Jiménez, Nadia Lis; Cantil, Liliana Fernanda; Fernández, R.; Porini, G. The objective of this study was to estimate and compare some important reproductive parameters of Myocastor coypus over time (June 2006-May 2008), in wetlands of the Middle Delta of the Paraná River (MD) Entre Ríos province, R. Argentina. Within the original coypu distribution range, the MD is among the areas of highest habitat suitability for the species. Coypus were captured and the following reproductive parameters were estimated on a monthly, seasonal and annual basis: pregnancy rate (PR), litter size (LS), gross productivity (GP) and annual production (AP). Statistical non-parametric tests were used for comparisons. Additionally, the expected birth date of each embryo and fetus was estimated by assigning it to a developmental stage category and considering the gestation period of the species. All the parameters showed high values and PR and LS differed significantly between the dry (2006) and humid years (2007). Two peaks of birth were detected, one in spring and another one in mid-autumn. The implications of these results for ensuring the sustainable management of this rodent are discussed.; O objetivo deste trabalho é a descripção e comparação ao longo do tempo (junho 2006 – maio 2008), de diversos parámetros da ecologia reprodutiva de Myocastor coypus nas terras úmidas do Delta Meio do Río Paraná (DM), una das zonas de maior aptidão de hábitat para a espécie dentro da sua área de distribuição original. Com base em capturas de exemplares estimaram-se en forma mensal, sazonal y anual, a taxa de prenhez (TP); o tamanho da camada (TC), a produtividade bruta (PB) e a produção anual (PA) e foram realizadas as comparações correspondentes mediante provas estatísticas não paramétricas. Alem disso, com base no estádio de desenvolvimento dos fetos y embriões observados, levando em consideração a duração do período de gestação, estimou-se quais teriam sido as datas de nascimento mais prováveis. Observaram-se valores relativamente altos para todos os parámetros e diferenças significativas entre as TP y os TC de anos secos (2006) e anos úmidos (2007). Também foram detectados dois picos de parição, um em plena primavera e o outro a meados do outono. Discutem-se as implicâncias destes resultados para assegurar o manejo sustentável do coipo, o principal recurso de fauna silvestre argentina.

Implementation of HPV-testing for cervical cancer screening in programmatic contexts: The Jujuy demonstration project in Argentina Arrossi, Silvina; Thouyaret, Laura; Laudi, Rosa; Marín, Oscar; Ramírez, Josefina; Paolino, Melisa Delia; Herrero, Rolando; Campanera, Alicia The aim of this article is to present results of programmatic introduction of HPV testing with cytologic triage among women 30 years and older in the province of Jujuy, Argentina, including description of the planning phase and results of program performance during the first year. We describe the project implementation process, and calculate key performance indicators using SITAM, the national screening information system. We also compare disease detection rates of HPV testing in 2012 with cytology as performed during the previous year. HPV testing with cytology triage was introduced through a consensus-building process. Key activities included establishment of algorithms and guidelines, creating the HPV laboratory, training of health professionals, information campaigns for women and designing the referral network. By the end of 2012, 100% (n = 270) of public health care centers were offering HPV testing and 22,834 women had been HPV tested, 98.5% (n = 22,515) were 30+. HPV positivity among women over 30 was 12.7%, 807 women were HPV+ and had abnormal cytology, and 281 CIN2+ were identified. CIN2+ detection rates was 1.25 in 2012 and 0.62 in 2011 when the program was cytology based (p = 0.0002). This project showed that effective introduction of HPV testing in programmatic contexts of low-middle income settings is feasible and detects more disease than cytology.

New evidences of rupture of crust and mantle in the subducted Nazca plate at intermediate-depth Spagnotto, Silvana Liz; Triep, Enrique Gaudencio; Giambiagi, Laura Beatriz; Nacif Suvire, Silvina Valeria; Alvarez Pontoriero, Orlando Between 33°-36°S, the Nazca plate subducts below South American plate with an angle of ~30°, and it is seismically active until ~200-280km depth. At 33.5°S, the seismicity decreases drastically at 120km depth, just below the volcanic arc. In this paper, we studied a pair of associated earthquakes located in the area where the frequency of seismicity changes. The hypocenters of the Mw=6.4, June 16th, 2000 and Mw=5.7 January 7th, 2003 earthquakes were found nearby, adjacent to the oceanic Moho, closely associated with each other. The slip on the plane of the 2000 event produced Coulomb stress changes on the fault plane of 2003, both westward dipping, with a variation from ~1bar near the hypocenter of the latter to ~0.1bars in the deepest part of the plane. The two earthquakes combined process describes a normal focal mechanism, which cuts through the crust and breaks the mantle, reaching depths of ~40km below the Moho.The composed fault plane of the 2000 and 2003 events corresponds to a west-dipping normal fault with strike and dip consistent with those of the outer ridge faults. Thus, these events could be related to a preexisting fault originated in that environment reactivated at depth.The slip on the composed fault plane is consistent with the bending produced by the slab pull. Dehydration could be associated to these events.

Morphological and compositional characteristics of bimetallic core@shell nanoparticles revealed by MEIS Sanchez, Dario F.; Moiraghi, Raquel; Cometto, Fernando Pablo; Perez, Manuel Alejo; Fichtner, Paulo F. P.; Grande, Pedro L. In this paper we report the application of a suitable methodology to study the morphology, structure and composition of core@shell nanoparticles (NPs) systems with polydispersity in the shell thickness, with subnanometer resolution and good sampling. Through the combination of Medium Energy Ion Scattering with Transmission Electron Microscopy, we perform a systematic investigation on core@shell Au@Ag NPs synthesized by an original wet chemical method. For samples synthesized with baths of different AgNO3 concentrations, the present approach allowed us to determine the NP's Ag shell thicknesses distribution of about a few nanometers around the Au core.

Shiga toxins and stx phages: highly diverse entities Krüger, Alejandra; Lucchesi, Paula Maria Alejandra Shiga toxins are the main virulence factors of a group of Escherichia coli strains [Shiga toxin-producing E. coli (STEC)] that cause severe human diseases, such as haemorrhagic colitis and haemolytic–uraemic syndrome. The Shiga toxin family comprises several toxin subtypes, which have been differentially related to clinical manifestations. In addition, the phages that carry the Shiga toxin genes (stx phages) are also diverse. These phages play an important role not only in the dissemination of Shiga toxin genes and the emergence of new STEC strains, but also in the regulation of Shiga toxin production. Consequently, differences in stx phages may affect the dissemination of stx genes as well as the virulence of STEC strains. In addition to presenting an overview of Shiga toxins and stx phages, in this review we highlight current knowledge about the diversity of stx phages, with emphasis on its impact on STEC virulence. We consider that this diversity should be taken into account when developing STEC infection treatments and diagnostic approaches, and when conducting STEC control in reservoirs.

Identification of pyroxene minerals used as black pigments in painted human bones excavated in Northern Patagonia by Raman spectroscopy and XRD Tomasini, Eugenia Paula; Favier Dubois, Cristian Mario; Little, Nicole C.; Centeno, Silvia A.; Maier, Marta Silvia The skeletal remains of seven individuals were excavated in a secondary burial context in the site of Cima de los Huesos, in the San Matías Gulf (Río Negro, Argentina). AMS dating of two samples for this site to 1173 ± 45 and 1225 ± 47 years BP make it one of the earliest burials of its kind uncovered so far in the Patagonian region. Among the findings, the skeleton of a male painted with parallel lines alternating red and black colors was uncovered. SEM-EDS elemental analysis of microsamples removed from the red and the black pigments showed the presence of Mn and Fe as the main components, respectively. Raman microspectroscopy combined with micro-X-ray diffraction analysis showed that the red pigment contains hematite and that the black pigment is composed of members of the pyroxene mineral group, ferrosilite (FeSiO3) and enstatite (MgSiO3) along with kanoite (MnMgSi2O6). This is, to our knowledge, the first report on the use of pyroxenes as black pigments to decorate human remains or archeological artifacts in South America. No organic compounds that could have been used as binders for the paints were detected by FTIR-ATR. Contamination due to quartz and aluminosilicates, mainly microcline and albite, from the burial environment did not allow determining whether clay minerals were used in the paints as binders and/or extenders. The multitechnique approach used was crucial to overcome the limitations of the individual techniques to firmly identify Mn-containing black pigments.