1,626 research outputs found

    Forecasting Interest Rates: an application for Brazil

    Get PDF
    Understanding the links between long and short-term interest rates is crucial for monetary policy makers, since Central Banks decide and set short-term interest rates in order to affect indirectly long-term interest rates, which affects aggregate spending. This paper studies whether VAR/VEC models are useful in predicting long-term interest rates for Brazil. The empirical results suggest that these models are useful in building qualitative scenarios for the Term structure of interest rates, but do not provide good forecasts in terms of accuracy. Furthermore, models that assume that the future path of short-term interest rates (target interest rates) is known by forecasters do not perform better in terms of both directional and forecasting accuracy.

    Autômatos celulares unidimensionais caóticos com borda fixa aplicados à modelagem de um sistema criptográfico para imagens digitais

    Get PDF
    O principal objetivo da criptografia de dados é possibilitar que duas entidades se comuniquem ao longo de um canal inseguro, de tal forma que nenhum oponente consiga decifrar a mensagem que é enviada. Muitos métodos de criptografia clássica já foram investigados para minimizar este problema. Uma nova abordagem para este tema são os Autômatos Celulares (ACs), que estão sendo estudados por sua capacidade de processar grandes volumes de dados em paralelo. Nesse trabalho é investigado um novo modelo de autômato celular para criptografia de imagens, que tem como característica o uso do cálculo de pré-imagens. Resultados mostraram que o modelo tem grande potencial para a realização de cifragem de grandes volumes de dados

    Results of the engineering run of the coherent neutrino nucleus interaction experiment (CONNIE)

    Get PDF
    The CONNIE detector prototype is operating at a distance of 30 m from the core of a 3.8 GWth nuclear reactor with the goal of establishing Charge-Coupled Devices (CCD) as a new technology for the detection of coherent elastic neutrino-nucleus scattering. We report on the results of the engineering run with an active mass of 4 g of silicon. The CCD array is described, and the performance observed during the first year is discussed. A compact passive shield was deployed around the detector, producing an order of magnitude reduction in the background rate. The remaining background observed during the run was stable, and dominated by internal contamination in the detector packaging materials. The in-situ calibration of the detector using X-ray lines from fluorescence demonstrates good stability of the readout system. The event rates with the reactor ON and OFF are compared, and no excess is observed coming from nuclear fission at the power plant. The upper limit for the neutrino event rate is set two orders of magnitude above the expectations for the standard model. The results demonstrate the cryogenic CCD-based detector can be remotely operated at the reactor site with stable noise below2 e RMS and stable background rates. The success of the engineering test provides a clear path for the upgraded 100 g detector to be deployed during 2016.Fil: Aguilar Arevalo, A.. Universidad Nacional Autónoma de México; MéxicoFil: Bertou, Xavier Pierre Louis. Comisión Nacional de Energía Atómica; Argentina. Comisión Nacional de Energía Atómica. Fundación José A. Balseiro; ArgentinaFil: Bonifazi, C.. Universidade Federal do Rio de Janeiro; BrasilFil: Butner, M.. Fermi National Accelerator Laboratory; Estados UnidosFil: Cancelo, G.. Fermi National Accelerator Laboratory; Estados UnidosFil: Castañeda Vazquez, A.. Universidad Nacional Autónoma de México; MéxicoFil: Cervantes Vergara, B.. Universidad Nacional Autónoma de México; MéxicoFil: Chavez, C. R.. Universidad Nacional de Asunción; ParaguayFil: Da Motta, H.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: D'Olivo, J. C.. Universidad Nacional Autónoma de México; MéxicoFil: Dos Anjos, J.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Estrada, J.. Fermi National Accelerator Laboratory; Estados UnidosFil: Fernández Moroni, Guillermo. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ford, R.. Fermi National Accelerator Laboratory; Estados UnidosFil: Foguel, A.. Centro Brasileiro de Pesquisas Físicas; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Hernandez Torres, K. P.. Universidad Nacional Autónoma de México; MéxicoFil: Izraelevitch, F.. Fermi National Accelerator Laboratory; Estados UnidosFil: Kavner, A.. University of Michigan; Estados UnidosFil: Kilminster, B.. Universitat Zurich; SuizaFil: Kuk, K.. Fermi National Accelerator Laboratory; Estados UnidosFil: Lima Jr, H. P.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Makler, M.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Molina, J.. Universidad Nacional de Asunción; ParaguayFil: Moreno Granados, G.. Universidad Nacional Autónoma de México; MéxicoFil: Moro, Juan Manuel. Universidad Nacional del Sur. Departamento de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Paolini, Eduardo Emilio. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto ; ArgentinaFil: Sofo Haro, Miguel Francisco. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Trillaud, F.. Universidad Nacional Autónoma de México; MéxicoFil: Wagner, S.. Centro Brasileiro de Pesquisas Físicas; Brasil. Pontificia Universidade Católica do Rio Grande do Sul; Brasi

    Citalopram administration does not promote function or histological recovery after spinal cord injury

    Get PDF
    Citalopram is a selective serotonin reuptake inhibitor, and although widely used as an antidepressant, this drug has also demonstrated interesting repairing properties leading to motor recovery and pathology amelioration in animal models of stroke and degeneration. Here, we tested the efficacy of both 7-day and 8-week citalopram treatment in a contusive spinal cord injury (SCI) rat model. A combination of behavioral tests, histological and serum cytokine analysis was used to assess overall recovery. Despite promoting a mild reduction of inflammatory cells as well as an early, but transient increase of specific serum cytokines, citalopram administration showed no overall beneficial effects on motor performance or lesion extension. Our results do not support citalopram treatment as a therapeutic strategy for SCI.This research was funded by Prémios Santa Casa Neurociências—Prize Melo e Castro for SpinalCord Injury Research, Grant Number MC-04/17 and the Portuguese Foundation for Science and Technology(FCT) through the Scientific Employment Stimulus to N. Silva and S. Monteiro (CEECIND/04794/2017 and CEECIND/01902/2017) and fellowships to RL (PD/BDE/127836/2016); EDG (SFRH/BD/103075/2014);NLV (SFRH/BD/136952/2018) and R.AS (PDE/BDE/113596/2015).This work was also funded by FEDER,through the Competitiveness Internalization Operational Program (POCI) and by National funds, throughthe Foundation for Sciences and Technology (FCT), under the scope of the projects POCI-01-0145-FEDER-007038,POCI-01-0145-FEDER-029206, POCI-01-0145-FEDER-029751 and PTDC/BTM-MAT/29968/2017. This work hasbeen funded by ICVS Scientific Microscopy Platform, member of the national infrastructure PPBI - PortuguesePlatform of Bioimaging (PPBI-POCI-01-0145-FEDER-022122; by National funds, through the Foundationfor Science and Technology (FCT) - project UIDB/50026/2020 and UIDP/50026/2020; and by the projectsNORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Program (NORTE2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)

    Synthesis of Selenium-Quinone Hybrid Compounds with Potential Antitumor Activity via Rh-Catalyzed C-H Bond Activation and Click Reactions

    Get PDF
    In continuation of our quest for new redox-modulating catalytic antitumor molecules, selenium-containing quinone-based 1,2,3-triazoles were synthesized using rhodium-catalyzed C-H bond activation and click reactions. All compounds were evaluated against five types of cancer cell lines: HL-60 (human promyelocytic leukemia cells), HCT-116 (human colon carcinoma cells), SF295 (human glioblastoma cells), NCIH-460 (human lung cells) and PC3 (human prostate cancer cells). Some compounds showed good activity with IC50 values below 1 µM. The cytotoxic potential of the naphthoquinoidal derivatives was also evaluated in non-tumor cells, exemplified by L929 cells. Overall, these compounds represent promising new lead derivatives and stand for a new class of chalcogenium-containing derivatives with potential antitumor activity

    Decomposition and nutrient release of leguminous plants in coffee agroforestry systems.

    Get PDF
    Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and(lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants

    Bioengineered cell culture systems of central nervous system injury and disease

    Get PDF
    Cell culture systems, either 2D or explant based, have been pivotal to better understand the pathophysiology of several central nervous system (CNS) disorders. Recently, bioengineered cell culture systems have been proposed as an alternative to the traditional setups. These innovative systems often combine different cell populations in 3D environments that more closely recapitulate the different niches that exist within the developing or adult CNS. Given the importance of such systems for the future of CNS-related research, we discuss here the most recent advances in the field, particularly those dealing with neurodegeneration, neurodevelopmental disorders, and trauma.Financial support is acknowledged from Prémios Santa Casa Neurociências – Prize Melo e Castro for Spinal Cord Injury Research; Portuguese Foundation for Science and Technology [Doctoral fellowship (SFRH/BD/103075/2014) to E.D.G.; IF Development Grant to A.J.S.; Starting Grant to F. Marques; PostDoctoral fellowship SFRH/BPD/97701/2013 to N.A.S.]; this work was co-funded by Programa Operacional Regional do Norte (ON.2 – O Novo Norte), ao abrigo do Quadro de Referência Estratégico Nacional (QREN), através do Fundo Europeu de Desenvolvimento Regional (FEDER).info:eu-repo/semantics/publishedVersio

    Green manure in coffee systems in the region of Zona da Mata, Minas Gerais: characteristics and kinetics of carbon and nitrogen mineralization.

    Get PDF
    The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis)to produce above-ground biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation.C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by the altitude and position of the area relative to the sun
    corecore