230 research outputs found

    Módulos multimídia para o ensino de sistemas de telecomunicações

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    A tecnologia multimídia fornece elementos para uma concepção integridade transmissão do conhecimento, onde se exige maior comprometimento por parte do aluno, aumentando a sua responsabilidade, encorajando-o ao controle do seu aprendizado. A capacidade de combinar aplicações práticas, visualizações de fenômenos complexos, laboratórios virtuais, animações e a utilização auto assistida de aplicativos de simulação são algumas das vantagens da educação baseada em técnicas multimídia. Este trabalho descreve o desenvolvimento de um ambiente multimídia na forma de CD-ROM, para a área de Sistemas de Telecomunicações. OCD-ROM foi concebido para ser utilizado em atividades de extensão, de maneira a facilitar a aprendizagem e atualização do estudante, de forma mais descentralizada, considerando seus interesses e sua disponibilidade

    Long term measurements of aerosol optical properties at a primary forest site in Amazonia

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    A long term experiment was conducted in a primary forest area in Amazonia, with continuous in-situ measurements of aerosol optical properties between February 2008 and April 2011, comprising, to our knowledge, the longest database ever in the Amazon Basin. Two major classes of aerosol particles, with significantly different optical properties were identified: coarse mode predominant biogenic aerosols in the wet season (January-June), naturally released by the forest metabolism, and fine mode dominated biomass burning aerosols in the dry season (July-December), transported from regional fires. Dry particle median scattering coefficients at the wavelength of 550 nm increased from 6.3 Mm(-1) to 22 Mm(-1), whereas absorption at 637 nm increased from 0.5 Mm(-1) to 2.8 Mm(-1) from wet to dry season. Most of the scattering in the dry season was attributed to the predominance of fine mode (PM2) particles (40-80% of PM10 mass), while the enhanced absorption coefficients are attributed to the presence of light absorbing aerosols from biomass burning. As both scattering and absorption increased in the dry season, the single scattering albedo (SSA) did not show a significant seasonal variability, in average 0.86 +/- 0.08 at 637 nm for dry aerosols. Measured particle optical properties were used to estimate the aerosol forcing efficiency at the top of the atmosphere. Results indicate that in this primary forest site the radiative balance was dominated by the cloud cover, particularly in the wet season. Due to the high cloud fractions, the aerosol forcing efficiency absolute values were below -3.5 Wm(-2) in 70% of the wet season days and in 46% of the dry season days. Besides the seasonal variation, the influence of out-of-Basin aerosol sources was observed occasionally. Periods of influence of the Manaus urban plume were detected, characterized by a consistent increase on particle scattering (factor 2.5) and absorption coefficients (factor 5). Episodes of biomass burning and mineral dust particles advected from Africa were observed between January and April, characterized by enhanced concentrations of crustal elements (Al, Si, Ti, Fe) and potassium in the fine mode. During these episodes, median particle absorption coefficients increased by a factor of 2, whereas median SSA values decreased by 7 %, in comparison to wet season conditions.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)European Integrated FP6 project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) under the scope of LBA experimentUniversidade Federal de São Paulo, Inst Environm Chem & Pharmaceut Sci, Dept Earth & Exact Sci, São Paulo, BrazilUniv São Paulo, Inst Phys, Dept Appl Phys, São Paulo, BrazilLeibniz Inst Tropospher Res, Leipzig, GermanyNatl Inst Amazonian Res INPA, Manaus, Amazonas, BrazilLund Univ, Inst Phys, Div Nucl Phys, Lund, SwedenHarvard Univ, Dept Earth & Planetary Sci, Div Engn & Appl Sci, Cambridge, MA 02138 USAUniv Helsinki, Div Atmospher Sci, Dept Phys Sci, Helsinki, FinlandUniversidade Federal de São Paulo, Inst Environm Chem & Pharmaceut Sci, Dept Earth & Exact Sci, São Paulo, BrazilFAPESP: AEROCLIMA 08/58100-2European Integrated FP6 project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) under the scope of LBA experiment: 34684Web of Scienc

    Variability in herbivore-induced defence signalling across different maize genotypes impacts significantly on natural enemy foraging behaviour

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    ‘Smart’ plants that release volatile defence compounds in response to pest damage, and which recruit beneficial natural enemies, offer an opportunity for exploiting biological control in future crop protection strategies. Using six maize genotypes, Zapalote Chico (‘landrace’), Mirt2A, Sintético Spodoptera (SS), L3, and two commercial hybrids BRS 4103 and BRS 1040, the aim of this work was to evaluate maize responses to larval damage from the fall armyworm Spodoptera frugiperda, a major maize pest in Brazil, and the ability of the egg parasitoid Telenomus remus to respond to HIPVs induced by S. frugiperda damage. Y-tube olfactometer bioassays with T. remus showed preferential responses to the S. frugiperda-induced volatiles of SS and BRS 4103 compared to constitutive volatiles of the same genotypes, but to none of the other genotypes tested. Chemical analysis of maize volatile extracts showed that SS produced more volatile compounds in response to S. frugiperda damage, followed by BRS 4103. In addition, higher levels of mono, homo-, or sesquiterpenes, together with green leaf volatiles (GLVs) were the most attractive blend for T. remus; however, there was no attraction when only GLVs were produced in higher levels. In summary, these results show that volatile defence signalling produced by maize plants due to S. frugiperda damage varies significantly depending on maize genotype and this variability influences T. remus foraging behaviour

    Differential effects of antigens from L. braziliensis isolates from disseminated and cutaneous leishmaniasis on in vitro cytokine production

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    BACKGROUND: Disseminated leishmaniasis is an emerging infectious disease, mostly due to L. braziliensis, which has clinical and histopathological features distinct from cutaneous leishmaniasis. METHODS: In the current study we evaluated the in vitro production of the cytokines IFN-γ, TNF-α, IL-5 and IL-10 by peripheral blood mononuclear cells (PBMC) from 15 disseminated leishmaniasis and 24 cutaneous leishmaniasis patients upon stimulation with L. braziliensis antigens genotyped as disseminated leishmaniasis or cutaneous leishmaniasis isolates. RESULTS: Regardless of the source of L. braziliensis antigens, PBMC from cutaneous leishmaniasis patients produced significantly higher IFN-γ than PBMC from disseminated leishmaniasis patients. Levels of TNF-α by PBMC from cutaneous leishmaniasis patients were significantly higher than disseminated leishmaniasis patients only when stimulated by genotyped cutaneous leishmaniasis antigens. The levels of IL-5 and IL-10 production by PBMC were very low and similar in PBMCs from both disseminated leishmaniasis and cutaneous leishmaniasis patients. The immune response of each patient evaluated by the two L. braziliensis antigens was assessed in a paired analysis in which we showed that L. braziliensis genotyped as disseminated leishmaniasis isolate was more potent than L. braziliensis genotyped as cutaneous leishmaniasis isolate in triggering IFN-γ and TNF-α production in both diseases and IL-5 only in cutaneous leishmaniasis patients. CONCLUSION: This study provides evidence that antigens prepared from genotypically distinct strains of L. braziliensis induce different degrees of immune response. It also indicates that both parasite and host play a role in the outcome of L. braziliensis infection

    Inhibitory effect of microalgae and cyanobacteria extracts on influenza virus replication and neuraminidase activity

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    Background The influenza virus can cause seasonal infections with mild to severe symptoms, circulating worldwide, and it can affect people in any age group. Therefore, this infection is a serious public health problem that causes severe illness and death in high-risk populations. Every year, 0.5% of the world’s population is infected by this pathogen. This percentage can increase up to ten times during pandemics. Influenza vaccination is the most effective way to prevent disease. In addition, anti-influenza drugs are essential for prophylactic and therapeutic interventions. The oseltamivir (OST, a neuraminidase inhibitor) is the primary antiviral used in clinics during outbreaks. However, OST resistant viruses may emerge naturally or due to antiviral pressure, with a prevalence of 1–2% worldwide. Thus, the search for new anti-influenza drugs is extremely important. Currently, several groups have been developing studies describing the biotechnological potential of microalgae and cyanobacteria, including antiviral activity of their extracts. In Brazil, this potential is poorly known and explored. Methods With the aim of increasing the knowledge on this topic, 38 extracts from microalgae and cyanobacteria isolated from marine and freshwater biomes in Brazil were tested against: cellular toxicity; OST-sensitive and resistant influenza replications; and neuraminidase activity. Results For this purpose, Madin-Darby Canine Kidney (MDCK)-infected cells were treated with 200 μg/mL of each extract. A total of 17 extracts (45%) inhibited influenza A replication, with seven of them resulting in more than 80% inhibition. Moreover, functional assays performed with viral neuraminidase revealed two extracts (from Leptolyngbya sp. and Chlorellaceae) with IC50 mean < 210 μg/mL for influenza A and B, and also OST-sensitive and resistant strains. Furthermore, MDCK cells exposed to 1 mg/mL of all the extracts showed viability higher than 80%. Discussion Our results suggest that extracts of microalgae and cyanobacteria have promising anti-influenza properties. Further chemical investigation should be conducted to isolate the active compounds for the development of new anti-influenza drugs. The data generated contribute to the knowledge of the biotechnological potential of Brazilian biomes that are still little explored for this purpose

    Impactos ambientais do manejo agroecológico da caatinga no Rio Grande do Norte.

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    O objetivo deste trabalho foi avaliar os impactos ambientais do manejo agroecológico da caatinga, em unidades de produção familiar no Rio Grande do Norte, pelo método Ambitec de produção animal - dimensão ambiental, desenvolvido pela Embrapa Meio Ambiente. Foram avaliadas sete unidades de produção familiar, em quatro projetos de assentamentos de reforma agrária do Município de Apodi, RN. Os dados para o levantamento foram obtidos por meio de questionários aplicados aos representantes das unidades produtivas familiares, que atribuíram, a cada variável estudada, um valor que representou a alteração proporcionada pela implementação da tecnologia. Após a inserção dos coeficientes de alteração de cada variável dos indicadores por unidade de produção, o coeficiente de impacto foi automaticamente calculado por meio da planilha Ambitec. O manejo agroecológico da caatinga resultou num impacto ambiental positivo, e suas maiores contribuições foram relacionadas aos efeitos positivos dos seguintes indicadores: capacidade produtiva do solo, uso de insumos materiais, qualidade do produto e diminuição da emissão de poluentes à atmosfera. Dois indicadores geraram efeitos negativos: o uso de energia e o uso de recursos naturais. Pela superioridade dos benefícios gerados, o manejo agroecológico da caatinga é uma inovação tecnológica geradora de impactos ambientais positivos

    Nutritional status of pre-school children from low income families

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    <p>Abstract</p> <p>Background</p> <p>We evaluated growth and nutritional status of preschool children between 2 and 6 years old from low income families from 14 daycare centers.</p> <p>Methods</p> <p>Cross-sectional study with 1544 children from daycare centers of Santo Andre, Brazil. Body weight (W), height (H) and body mass index (BMI) were classified according to the 2000 National Center for Health Statistics (CDC/NCHS). Cutoff points for nutritional disorders: -2 z scores and 2.5 and 10 percentiles for malnutrition risk, 85 to 95 percentile for overweight and above BMI 95 percentile for obesity. Stepwise Forward Regression method was used including age, gender, birth weight, breastfeeding duration, age of mother at birth and period of time they attended the daycare center.</p> <p>Results</p> <p>Children presented mean z scores of H, W and BMI above the median of the CDC/NCHS reference. Girls were taller and heavier than boys, while we observed similar BMI between both genders. The z scores tended to rise with age. A Pearson Coefficient of Correlation of 0.89 for W, 0.93 for H and 0.95 for BMI was documented indicating positive association of age with weight, height and BMI. The frequency of children below -2 z scores was lower than expected: 1.5% for W, 1.75% for H and 0% for BMI, which suggests that there were no malnourished children. The other extremity of the distribution evidenced prevalence of overweight and obesity of 16.8% and 10.8%, respectively.</p> <p>Conclusion</p> <p>Low income preschool children are in an advanced stage of nutritional transition with a high prevalence of overweight.</p

    The association of myocardial strain with cardiac magnetic resonance and clinical outcomes in patients with acute myocarditis

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    IntroductionThe role of myocardial strain in risk prediction for acute myocarditis (AMC) patients, measured by cardiac magnetic resonance (CMR), deserves further investigation. Our objective was to evaluate the association between myocardial strain measured by CMR and clinical events in AMC patients.Material and methodsThis was a prospective single-center study of patients with AMC. We included 100 patients with AMC with CMR confirmation. The primary outcome was the composite of all-cause mortality, heart failure and AMC recurrence in 24 months. A subgroup analysis was performed on a sample of 36 patients who underwent a second CMR between 6 and 18 months. The association between strain measures and clinical events or an increase in left ventricular ejection fraction (LVEF) was explored using Cox regression analysis. Global peak radial, circumferential and longitudinal strain in the left and right ventricles was assessed. ROC curve analysis was performed to identify cutoff points for clinical event prediction.ResultsThe mean follow-up was 18.7 ± 2.3 months, and the composite primary outcome occurred in 26 patients. The median LVEF at CMR at baseline was 57.5% (14.6%). LV radial strain (HR = 0.918, 95% CI: 0.858–0.982, p = 0.012), LV circumferential strain (HR = 1.177, 95% CI: 1.046–1.325, p = 0.007) and LV longitudinal strain (HR = 1.173, 95% CI: 1.031–1.334, p = 0.015) were independently associated with clinical event occurrence. The areas under the ROC curve for clinical event prediction were 0.80, 0.79 and 0.80 for LV radial, circumferential, and longitudinal strain, respectively. LV longitudinal strain was independently correlated with prognosis (HR = 1.282, CI 95%: 1.022–1.524, p = 0.007), even when analyzed together with ejection fraction and delayed enhancement. LV and right ventricle (RV) strain were not associated with an increase in LVEF. Finally, when the initial CMR findings were compared with the follow-up CMR findings, improvements in the measures of LV and RV myocardial strain were observed.ConclusionMeasurement of myocardial strain by CMR can provide prognostic information on AMC patients. LV radial, circumferential and longitudinal strain were associated with long-term clinical events in these patients
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