Analysis of the rod-drop experiments performed during the CABRI commissioning tests

International audienceCABRI is an experimental pulse reactor operated by the CEA at the Cadarache research center. After its refurbishment, it is now able to provide experiments in prototypical PWR conditions (155 bar, 300DC). Before operating, commissioning tests were performed, including control rod worth measurements. These experi-ments are done thanks to the rod-drop technique, which gathers static and dynamic effects. This paper reminds the theoretical background of the rod drop analysis. Then it gives a rigorous definition for the MSM factors (i.e. spatial correction factors to take into account the modification of the detector efficiency). An uncertainty analysis is performed and results prove the validity of the proposed model. Finally, the conclusion focuses on some possible improvements, like a rigorous importance calculation using the stochastic code TRIPOLI-4 and the use of different nuclear data libraries

Lucha de titanes, neohelice granulata vs. cyrtograpsus angulatus ¿cuál es el mejor bioindicador de metales pesados? : un estudio comparativo en una zona interna del Estuario de Bahía Blanca

El Estuario de Bahía Blanca es un humedal localizado en el sudoeste de la costa bonaerense, que posee un clima templado perteneciente a la ecorregión patagónica. El aporte de agua dulce proveniente de ríos es escaso en comparación a otros grandes estuarios como el de La Plata y se ha configurado en una región única de mayores ingresiones marinas. Para referirse a este ambiente, se ha acuñado el término “ría" que emerge como una construcción social de los pobladores que refieren a este humedal de transición con contribuciones de pequeños arroyos o riachos. La presión antrópica histórica sobre el estuario basado en las actividades extractivas, lo han convertido en un escenario ecológicamente sacrificable para muchas especies animales y socialmente vaciable para quienes desarrollan sus pequeñas economías en este humedal. Por tanto, es interesante analizar las condiciones ecológicas de este ecosistema desde una perspectiva integral, considerando los organismos que habitan en relación a este espacio y a los contaminantes que amenazan su sostenibilidad ecológica. En este sentido, en el presente trabajo nos proponemos a analizar dos especies de crustáceos decápodos varúnidos (Neohelice granulata y Cyrtograpsus angulatus) para determinar cuál podría ser el mejor indicador biológico (bioindicador) de metales pesados. Este análisis nos presentará información que nos permitirá conocer la salud de los organismos y del ecosistema en el que habitan, que sean de utilidad para generar información para aplicarse a políticas públicas que protejan la biodiversidad de grandes humedales de importancia socio-cultural, económica y ecológica.Fil: Truchet, Daniela M.. Instituto Argentino de OceanografíaFil: Buzzi, Natalia. Instituto Argentino de OceanografíaFil: Marcovecchio, Jorge. Instituto Argentino de Oceanografí

Characterisation of adipocyte-derived extracellular vesicle subtypes identifies distinct protein and lipid signatures for large and small extracellular vesicles

Extracellular vesicles (EVs) are biological vectors that can modulate the metabolism of target cells by conveying signalling proteins and genomic material. The level of EVs in plasma is significantly increased in cardiometabolic diseases associated with obesity, suggesting their possible participation in the development of metabolic dysfunction. With regard to the poor definition of adipocyte-derived EVs, the purpose of this study was to characterise both qualitatively and quantitatively EVs subpopulations secreted by fat cells. Adipocyte-derived EVs were isolated by differential centrifugation of conditioned media collected from 3T3-L1 adipocytes cultured for 24 h in serum-free conditions. Based on morphological and biochemical properties, as well as quantification of secreted EVs, we distinguished two subpopulations of adipocyte-derived EVs, namely small extracellular vesicles (sEVs) and large extracellular vesicles (lEVs). Proteomic analyses revealed that lEVs and sEVs exhibit specific protein signatures, allowing us not only to define novel markers of each population, but also to predict their biological functions. Despite similar phospholipid patterns, the comparative lipidomic analysis performed on these EV subclasses revealed a specific cholesterol enrichment of the sEV population, whereas lEVs were characterised by high amounts of externalised phosphatidylserine. Enhanced secretion of lEVs and sEVs is achievable following exposure to different biological stimuli related to the chronic low-grade inflammation state associated with obesity. Finally, we demonstrate the ability of primary murine adipocytes to secrete sEVs and lEVs, which display physical and biological characteristics similar to those described for 3T3-L1. Our study provides additional information and elements to define EV subtypes based on the characterisation of adipocyte-derived EV populations. It also underscores the need to distinguish EV subpopulations, through a combination of multiple approaches and markers, since their specific composition may cause distinct metabolic responses in recipient cells and tissues

Experimental Evolution of a Plant Pathogen into a Legume Symbiont

Following acquisition of a rhizobial symbiotic plasmid, adaptive mutations in the virulence pathway allowed pathogenic Ralstonia solanacearum to evolve into a legume symbiont under plant selection

Programmable disorder in random DNA tilings

Scaling up the complexity and diversity of synthetic molecular structures will require strategies that exploit the inherent stochasticity of molecular systems in a controlled fashion. Here we demonstrate a framework for programming random DNA tilings and show how to control the properties of global patterns through simple, local rules. We constructed three general forms of planar network—random loops, mazes and trees—on the surface of self-assembled DNA origami arrays on the micrometre scale with nanometre resolution. Using simple molecular building blocks and robust experimental conditions, we demonstrate control of a wide range of properties of the random networks, including the branching rules, the growth directions, the proximity between adjacent networks and the size distribution. Much as combinatorial approaches for generating random one-dimensional chains of polymers have been used to revolutionize chemical synthesis and the selection of functional nucleic acids, our strategy extends these principles to random two-dimensional networks of molecules and creates new opportunities for fabricating more complex molecular devices that are organized by DNA nanostructures

ANALYSE HISTOLOGIQUE PAR MICROSPECTROMÉTRIE RAMAN

La microspectrométrie Raman permet d'obtenir des spectres de vibration moléculaire à partir de prises d'essais de 10-11g, directement sous le microscope. Les structures d'accumulation de composés puriques, les précipitations minéralisées naturelles ou pathologiques peuvent ainsi être directement caractérisées sur coupes histologiques. Dans l'état actuel de son instmunentation et de sa méthodologie, la microspectrométrie Raman ne s'adresse qu'aux cas de bioaccumulations, mais des progrès importants peuvent être espérés dans un proche avenir.Raman microspectrometry allows to characterize directly into cells and tissues in very small samples (10-11g) any kind of metabolism products : purinic components, natural and pathological mineral precipitations, secretion products. In the present state of the art, only bioaccumulations leads to spectmun, but important progress are possible in a near future

ESSAI D'ANALYSE QUANTITATIVE PAR ÉMISSION IONIQUE SECONDAIRE SUR COUPES HISTOLOGIQUES

En raison de la multiplicité des facteurs qui influent sur l'émission ionique secondaire, l'analyse quantitative précise sur coupes histologiques se heurte à des difficultés quasi insurmontables. Pour tenter d'y pallier, une méthode de détermination des rendements ioniques est exposée, et quelques exemples sont fournis pour Na, K, Ca et Al dans le foie de souris, soit fixé, soit congelé.Emission yields are almost impossible to calculate in histological samples, because multiple parmeters are involved. A practical method is proposed to evaluate them experimentally. Exemples are given for Na, K, Ca and Al in fixed or frozen mice liver

Para desarmar el péndulo: Redefiniciones teórico-epistémicas en el estudio de la Policía Comunitaria de Santa Fe

In 2017, for my degree thesis, we decided to compare two community policing programs in the city of Santa Fe. In 2018, one of the empirical referent, the Santa Fe Community Police was disbanded. This police unit had the largest number of agents throughout the Province and was the specialized segment most legitimized by the citizens. This article proposes to reconstruct the obstacles, challenges and responses that we went through to explain the dissolution of the Community Police. The idea of “pendulation” in security policies is put in tension to slide towards a thought that puts a specific force as an effect of political disputes around the definition of the police and the mechanisms to govern it. Likewise, this way of understanding the problem was produced by positively integrating access and restriction to the field as an analytical input.Em 2017, para a minha tese, propusemo-nos a comparar dois modelos de policiamento comunitário na cidade de Santa Fé. Em 2018, um dos marcos empíricos, a Polícia Comunitária de Santa Fé, foi extinta. Esta unidade policial tinha o maior número de agentes em toda a Província e era o segmento especializado mais legitimado pelos cidadãos. Este artigo se propõe a reconstruir os obstáculos, desafios e respostas por que passamos para explicar a dissolução da Polícia Comunitária. A ideia de “pendulação” nas políticas de segurança é colocada em tensão para deslizar para um pensamento que tem uma força específica como efeito das disputas políticas em torno da definição da polícia e dos mecanismos para governá-la. Da mesma forma, essa forma de entender o problema foi produzida integrando positivamente o acesso e a restrição ao campo como insumo analítico.  En 2017 para mi tesina de grado en Ciencia Política nos propusimos comparar dos modelos de policiamiento comunitario en la ciudad de Santa Fe. En 2018, uno de los referentes empíricos, la Policía Comunitaria de Santa Fe se desarticuló. Dicha unidad policial poseía la mayor cantidad de agentes a lo largo de la Provincia y era el segmento especializado más legitimado por la ciudadanía. Este artículo propone reconstruir los obstáculos, desafíos y respuestas que recorrimos para explicar la disolución de la Policía Comunitaria. Se pone en tensión la idea de “pendulación” en las políticas de seguridad para deslizarse hacia un pensamiento que tiene a una fuerza concreta como efecto de disputas políticas en torno a la definición de la policía y los mecanismos para gobernarla. Asimismo, esta manera de comprender el problema se produjo integrando positivamente el acceso y restricción al campo como insumo analítico