857 research outputs found

    Representational organization of novel task sets during proactive encoding

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    Recent multivariate analyses of brain data have boosted our understanding of the organizational principles that shape neural coding. However, most of this progress has focused on perceptual visual regions (Connolly et al., 2012), whereas far less is known about the organization of more abstract, action-oriented representations. In this study, we focused on humans{\textquoteright} remarkable ability to turn novel instructions into actions. While previous research shows that instruction encoding is tightly linked to proactive activations in fronto-parietal brain regions, little is known about the structure that orchestrates such anticipatory representation. We collected fMRI data while participants (both males and females) followed novel complex verbal rules that varied across control-related variables (integrating within/across stimuli dimensions, response complexity, target category) and reward expectations. Using Representational Similarity Analysis (Kriegeskorte et al., 2008) we explored where in the brain these variables explained the organization of novel task encoding, and whether motivation modulated these representational spaces. Instruction representations in the lateral prefrontal cortex were structured by the three control-related variables, while intraparietal sulcus encoded response complexity and the fusiform gyrus and precuneus organized its activity according to the relevant stimulus category. Reward exerted a general effect, increasing the representational similarity among different instructions, which was robustly correlated with behavioral improvements. Overall, our results highlight the flexibility of proactive task encoding, governed by distinct representational organizations in specific brain regions. They also stress the variability of motivation-control interactions, which appear to be highly dependent on task attributes such as complexity or novelty.SIGNIFICANCE STATEMENTIn comparison with other primates, humans display a remarkable success in novel task contexts thanks to our ability to transform instructions into effective actions. This skill is associated with proactive task-set reconfigurations in fronto-parietal cortices. It remains yet unknown, however, how the brain encodes in anticipation the flexible, rich repertoire of novel tasks that we can achieve. Here we explored cognitive control and motivation-related variables that might orchestrate the representational space for novel instructions. Our results showed that different dimensions become relevant for task prospective encoding depending on the brain region, and that the lateral prefrontal cortex simultaneously organized task representations following different control-related variables. Motivation exerted a general modulation upon this process, diminishing rather than increasing distances among instruction representations

    Oferta de implantes de prótesis total de cadera en Cataluña

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    El crecimiento exponencial de la oferta de implantes de prótesis total de cadera hace difícil para el cirujano ortopédico establecer criterios de elección, por este motivo hemos realizado un análisis de la oferta actual de los mismos. Se han identificado 67 modelos de implantes de prótesis total de cadera primaria y 19 modelos de revisión comercializados en la comunidad catalana por 24 empresas. El número de variables, de material o diseño de los distintos modelos, sin tener en cuenta las diversas medidas de vástagos, cuellos y cótilos, ha sido de 55. Hemos encontrado referencias bibliográficas de resultados clínicos de un 25% de las prótesis. El rango de coste de los implantes ha sido de 70.000 a 300.570 pesetas para las prótesis cementadas, con un precio medio de 172.805 pesetas; de 375.654 a 648.606 pesetas para las no cementadas, con un precio medio de 480.301 pesetas, y de 412.552 a 713.000 pesetas de las prótesis de revisión, con una media de 568.138 pesetas. Esta dispersión de modelos y precios es mayor que la de otros países de nuestro entorno, y el porcentaje de publicaciones de resultados clínicos encontrado es algo menor que el reportado por algunos autores. Frente a esta situación creemos que serían necesarios estudios clínicos a largo término y sistemas de evaluación estandarizados para poder decidir con criterios rigurosos si los nuevos implantes que aparecen en el mercado con costes más elevados tienen ventajas suficientes para cambiar indicaciones de implantes largamente probados.The exponential growth of the different models of THA actually in offer makes difficult to the orthopaedic surgeon to find sound criteria for the selection of the proper implant. This paper is an attempt to analyse the models actually in offer. We have identified 67 primary THAs types and 19 revision models, commercialised by 24 companies at the catalonian community. The number of variables, materials or designs between different patterns, independently of the size of femoral and acetabular components, has been of 55. Only 25% of implants are supported by reports in the orthopaedic literature. The cost range of implants varied from 70,000 to 300,570 pts. for cemented prosthesis (average: 172,895); from 375,654 to 648,606 pts. for cementless models (average: 480,391); the cost range for revision models varied from 412,552 to 713,000 pts., with an average of 568,138 pts. Such a variety of designs and prices is greater than in other countries of our environment, and the percentage of reports about clinical results that we have found is smaller than the noticed by some authors. We believe that it would be necessary some long term prospective studies and standarized evaluation systems in order to decide if the newer implants, with more expensive price, have enough advantages to substitute the classic implants widely used

    Magnetic-properties of Cu-doped porous silica-gels - a possible Cu ferromagnet

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    We have studied the magnetic properties of Cu-doped porous silica gels and found that the system seems to be ferromagnetic up to room temperature. This result is fascinating because the amount of Cu ranges from 0.15% to 3% in weight of the total sample. Magnetization, hysteresis loops, and EPR experiments are presented. The paramagnetic signal of the silica gel without doping is negligible. On the other hand, the analysis of the magnetic impurities by x-ray fluorescence shows that these impurities can account for only 10% of the magnetization observed at 300 K

    Artificially induced reduction of the dissipation anisotropy in high-temperature superconductors

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    Bi_2Sr_2CaCu_2O_8, RBa_2Cu_3O_7 (R=Y, Eu) thin films and RBa_2Cu_3O_7/PrBa_2Cu_3O_7 superlattices have been fabricated by sputtering technique. The anisotropic dissipation was measured close to the critical temperatures with high applied magnetic fields rotating from parallel to perpendicular to the substrate. In multilayers, in a large magnetic field interval, the dissipation anisotropy is reduced as much as 60% in comparison with the most anisotropic system (Bi_2Sr_2CaCu_2O_8) and at least 50% at 30 kOe in comparison with 123 films. This strong anisotropy reduction is discussed taking into account the role played by the superlattice modulation lengths on magnetic matching effects and coupling between the superconducting layers

    Interface barriers for flux motion in high-temperature superconducting superlattices

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    We study angular dependent magnetoresistance in the vortex-liquid phase of epitaxial YBa2Cu3O7 thin films and YBa_2Cu_3O_7/PrBa_2Cu_3O_7 superlattices. Superlattices were grown with different PrBa_2Cu_3O_7 thickness in order to tune coupling between YBa_2Cu_3O_7 layers. While dissipation of single film and coupled superlattices is scaled with the anisotropic three-dimensional model in the whole angular range, decoupling through PrBa_2Cu_3O_7 spacer breaks down the scaling and yields strong reduction of the dissipation when the magnetic fields are applied up to ±20degrees around the interface direction. Bean-Livingston barriers at the interface are the mechanism which governs this behavior

    Blockade of T-cell activation by dithiocarbamates involves novel mechanisms of inhibition of nuclear factor of activated T cells.

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    Dithiocarbamates (DTCs) have recently been reported as powerful inhibitors of NF-kappaB activation in a number of cell types. Given the role of this transcription factor in the regulation of gene expression in the inflammatory response, NF-kappaB inhibitors have been suggested as potential therapeutic drugs for inflammatory diseases. We show here that DTCs inhibited both interleukin 2 (IL-2) synthesis and membrane expression of antigens which are induced during T-cell activation. This inhibition, which occurred with a parallel activation of c-Jun transactivating functions and expression, was reflected by transfection experiments at the IL-2 promoter level, and involved not only the inhibition of NF-kappaB-driven reporter activation but also that of nuclear factor of activated T cells (NFAT). Accordingly, electrophoretic mobility shift assays (EMSAs) indicated that pyrrolidine DTC (PDTC) prevented NF-kappaB, and NFAT DNA-binding activity in T cells stimulated with either phorbol myristate acetate plus ionophore or antibodies against the CD3-T-cell receptor complex and simultaneously activated the binding of AP-1. Furthermore, PDTC differentially targeted both NFATp and NFATc family members, inhibiting the transactivation functions of NFATp and mRNA induction of NFATc. Strikingly, Western blotting and immunocytochemical experiments indicated that PDTC promoted a transient and rapid shuttling of NFATp and NFATc, leading to their accelerated export from the nucleus of activated T cells. We propose that the activation of an NFAT kinase by PDTC could be responsible for the rapid shuttling of the NFAT, therefore transiently converting the sustained transactivation of this transcription factor that occurs during lymphocyte activation, and show that c-Jun NH2-terminal kinase (JNK) can act by directly phosphorylating NFATp. In addition, the combined inhibitory effects on NFAT and NF-KB support a potential use of DTCs as immunosuppressants

    Magnetic properties of ZnO nanoparticles

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    We experimentally show that it is possible to induce room-temperature ferromagnetic-like behavior in ZnO nanoparticles without doping with magnetic impurities but simply inducing an alteration of their electronic configuration. Capping ZnO nanoparticles (similar to 10 nm size) with different organic molecules produces an alteration of their electronic configuration that depends on the particular molecule, as evidenced by photoluminescence and X-ray absorption spectroscopies and altering their magnetic properties that varies from diamagnetic to ferromagnetic-like behavior

    Desafios do projeto transição produtiva e serviços ambientais na qualificação de políticas públicas voltadas ao setor rural.

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    Três medidas político-institucionais ocorridas no Brasil nas duas últimas décadas devem ser destacadas: (1) Lei 12.651/2012 (Novo Código Florestal), (2) Projeto de Lei (PL) 792/2007 (Serviços Ambientais) e (3) Lei 9.126/1995 (Taxa de Juros de Longo Prazo). Mas a falta de informações cientificamente validadas impede a operacionalização de incentivos econômicos para transição produtiva com pagamento de serviços ambientais. Nesse sentido, a Embrapa e entidades parceiras conceberam o Projeto Transição Produtiva e Serviços Ambientais, com o objetivo geral de "gerar e validar instrumentos e metodologias para apoiar políticas públicas de incentivo econômico a processos de transição produtiva de Sistemas Produtivos Integrados (SPIs) com capacidade de geração de renda e prestação de serviços ambientais em escala de paisagem rural". A fase I do projeto será executada entre 09/2013 e 09/2017, tendo como resultados esperados (1) validação científica de desenhos agronômicos de SPIs, (2) validação científica de coeficientes financeiros para potencializar adoção de SPIs via crédito rural, (3) validação científica de indicadores de serviços ambientais prestados e valoração de serviços ambientais por SPIs para viabilizar rebate ecológico no crédito rural e comercialização de produtos em mercados institucionais com preços diferenciados, (4) validação participativa de indicadores de serviços ambientais e de metodologia de certificação de serviços ambientais para atestar condicionalidades em políticas públicas e reduzir custos de transação do PSA, (5) análise comportamental sobre adoção de SPIs para subsidiar recomendações técnicas de TT e ATER e (6) disponibilização de banco de dados de acesso público

    Road network comparison and matching techniques. a workflow proposal for the integration of traffic message channel and open source network datasets

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    The rapid growth of methods and techniques to acquire geospatial data has led to a wide availability of overlapping geographic datasets with different characteristics. Road network data sources are today a significant number, with high differences in level of detail and modelling schemas, depending on the main purpose. In addition, continuous information about people and freight movement is today available also in real-time. This type of data is today exchanged between traffic operators using referencing standards as Traffic Message Channel. Integrating these heterogeneous databases, in order to build an added value product, is a serious task in geographical data management. The paper is focus on techniques to conflate the Traffic message Channel logical network on Open Source road network dataset, in order to allow the precise visualisation of traffic data also in real-time. A first step of the research was the quality assessment of available Open Source (OS) road network dataset, then, a specific procedure to conflate data was set up, using an iterative process in order to reduce at every step the number of possible matching features. A first application of the enhanced OTM dataset is shown for the city of Turin: real-time open data of traffic flows recorded by road network fixed sensors, made available by the metropolitan Traffic Operation Centre (5T) and based on the TMC location referencing, are matched on the OTM road network, allowing a detailed real-time visualisation of traffic state

    DEFINITION OF A METHODOLOGY TO DERIVE ROAD NETWORK FUNCTIONAL HIERARCHY CLASSES USING CAR TRACKING DATA

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    Road network functional hierarchy classifies individual roads into several levels, for efficient traffic management and road network generalization purposes. Automatic and semi-automatic road network extraction methods exist, but the generated products normally lack information on its functional hierarchy. This paper presents a methodology for automatically retrieve functional hierarchy for an OpenStreetMap derived road network from Floating Car Data, obtaining evenly distributed (e.g. for generalization purposes) or dynamic (e.g. to take into account differences in traffic volumes in different moments of the day) classifications. Road network elements are classified in function of vehicle speed values: the class distribution generated with the proposed methodology follows a linear distribution that can be better exploited for generalization purposes. Furthermore, the methodology allows to clearly distinguish different distributions in different moments of the day and days of the week, supporting traffic management activities
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