888 resultados para Two-stage stochastic model
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OBJETIVO: Estimar a prevalência de bronquite aguda, rinite e sinusite em crianças e adolescentes e identificar fatores associados. MÉTODOS: Estudo transversal, de base populacional. Foi realizado inquérito domiciliar com 1.185 crianças e adolescentes de São Paulo, SP, de 2008 a 2009. Os participantes foram selecionados a partir de amostragem probabilística, estratificada por sexo e idade e por conglomerados em dois estágios. Para análise ajustada foi realizada regressão múltipla de Poisson. RESULTADOS: Dos entrevistados, 7,3% referiram bronquite aguda, 22,6% rinite e 15,3% sinusite. Após análise ajustada, associaram-se à bronquite aguda auto-referida: idade de zero a quatro anos (RP = 17,86; IC95%: 3,65;90,91), cinco a nove anos (RP = 37,04; IC95%: 8,13;166,67), dez a 14 anos (RP = 20,83; IC95%: 4,93;90,91), referir ter alergia (RP = 3,12; IC95%: 1,70;5,73), cor da pele preta/parda (RP = 2,29; IC95%: 1,21;4,35) e morar em domicílio com um a três cômodos (RP = 1,85; IC95%: 1,17;2,94); à rinite auto-referida: idade dez a 14 anos (RP = 2,77; IC95%: 1,60;4,78), 15 a 19 anos (RP = 2,58; IC95%: 1,52;4,39), referir ter alergia (RP = 4,32; IC95%: 2,79;6,70), referir ter asma (RP = 2,30; IC95%: 1,30;4,10) e morar em apartamento (RP = 1,70; IC95%: 1,06;2,73); à sinusite auto-referida: idade cinco a nove anos (RP = 2,44; IC95%: 1,09;5,43), dez a 14 anos (RP = 2,99; IC95%: 1,36;6,58), 15 a 19 anos (RP = 3,62; IC95%: 1,68;7,81), referir ter alergia (RP = 2,23; IC95%: 1,41;3,52) e apresentar obesidade (RP = 4,42; IC95%: 1,56;12,50). CONCLUSÕES: As doenças respiratórias foram mais prevalentes em grupos populacionais com características definidas, como grupo etário, doenças auto-referidas, tipo de moradia e obesidade.
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With the search for treatments faster and aesthetic improvement of materials and surgical techniques, immediate implants have become a clinical reality increasingly practiced. Thus, based on literature the specific purpose of this study was to address critically the concepts of immediate implants, discussing issues related to dental extraction, milling technique, care of the periodontal tissues support and protection, prosthetic replacement, benefits, indications and contraindications. To this end, from Pubmed electronic crawler Medline, 54 articles published between 1990 and 2009, over 4 items classics, all in English were selected. The Studies have shown success rates for this technique Conventional techniques like two-stage surgery, many different techniques and planning are present among these techniques, and implants more immediate subject to failures.
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This paper shows the modeling and control of a single-phase full-bridge inverter with high-frequency transformer that may be used as part of a two-stage converter with transformerless DC-DC side or as a single-stage converter (simple DC-AC converter) for grid-connected PV applications. The inverter is modeled in order to obtain a small-signal transfer function used to design the P+Resonant current controller. A highfrequency step-up transformer results in reduced voltage switches and better efficiency compared with converters in which the transformer is used on the DC-DC side. Simulations and experimental results with a 200 W prototype are shown. 1
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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OBJECTIVE: To assess the prevalence of asthma and risk factors associated in children and adolescents. METHODS: Population-based cross-sectional study with 1,185 female and male children and adolescents carried out in the city of Sao Paulo, Southeastern Brazil, from 2008 to 2009. Data were collected through home interviews. Respondents were selected from two-stage (census tract, household) cluster random sampling stratified by gender and age. Multiple Poisson regression was used in the adjusted analysis between the outcome and socioeconomic, demographic, lifestyle and health condition variables. RESULTS: Of all respondents, 9.1% (95%CI 7.0; 11.7) reported asthma. After adjustment, the following variables were found independently associated with asthma: age (0 to 4 years vs. 15 to 19) (PR 3.18, 95%CI 1.20;8.42); age (5 to 9 years vs. 15 to 19) (PR 6.37, 95%CI 2.64;15.39); age (10 to 14 years vs. 15 to 19) (PR 4.51,95%CI 1.95;10.40); allergy (yes vs. no) (PR 2.22, 95%CI 1.24;4.00); rhinitis (yes vs. no) (PR 2.13, 95%CI 1.22;3.73); health conditions in the 15 days preceding the interview (yes vs. no) (PR 1.96, 95%CI 1.23;3.11); number of rooms in the household (1 to 3 vs. 4 and more) (PR 1.67, 95%CI 1.05;2.66); and skin color (black and mixed vs. white) (PR 2.00, 95%CI 1.14;3.49). CONCLUSIONS: This study showed the importance of factors associated with asthma including rhinitis and allergy; age between 5 to 9 years old; black and mixed skin color; and household with few rooms. Frequent health problems are seen as a common consequence of asthma.
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Little is known about the situational contexts in which individuals consume processed sources of dietary sugars. This study aimed to describe the situational contexts associated with the consumption of sweetened food and drink products in a Catholic Middle Eastern Canadian community. A two-stage exploratory sequential mixed-method design was employed with a rationale of triangulation. In stage 1 (n = 62), items and themes describing the situational contexts of sweetened food and drink product consumption were identified from semi-structured interviews and were used to develop the content for the Situational Context Instrument for Sweetened Product Consumption (SCISPC). Face validity, readability and cultural relevance of the instrument were assessed. In stage 2 (n = 192), a cross-sectional study was conducted and exploratory factor analysis was used to examine the structure of themes that emerged from the qualitative analysis as a means of furthering construct validation. The SCISPC reliability and predictive validity on the daily consumption of sweetened products were also assessed. In stage 1, six themes and 40-items describing the situational contexts of sweetened product consumption emerged from the qualitative analysis and were used to construct the first draft of the SCISPC. In stage 2, factor analysis enabled the clarification and/or expansion of the instrument's initial thematic structure. The revised SCISPC has seven factors and 31 items describing the situational contexts of sweetened product consumption. Initial validation of the instrument indicated it has excellent internal consistency and adequate test-retest reliability. Two factors of the SCISPC had predictive validity for the daily consumption of total sugar from sweetened products (Snacking and Energy demands) while the other factors (Socialization, Indulgence, Constraints, Visual Stimuli and Emotional needs) were rather associated to occasional consumption of these products.
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Optical memories with long-term stability at high temperatures have long been pursued in azopolymers with photoinduced birefringence. In this study, we show that the residual birefringence in layer-by-layer (LbL) films made with poly[1-[4-(3-carboxy-4 hydroxyphenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) alternated with poly(allylamine hydrochloride) (PAH) can be tuned by varying the extent of electrostatic interactions with film fabrication at different pHs for PAH. The dynamics of both writing and relaxation processes could be explained with a two-stage mechanism involving the orientation of the chromophores per se and the chain movement. Upon calculating the activation energies for these processes, we demonstrate semiquantitatively that reduced electrostatic interactions in films prepared at higher pH, for which PAH is less charged, are responsible for the longer stability at high temperatures. This is attributed to orientation of PAZO chromophores via cooperative aggregation, where the presence of counterions hindered relaxation.
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Batch combustion of fixed beds of coal, bagasse and blends thereof took place in a pre-heated two-stage electric laboratory furnace, under high-heating rates. The average input fuel/air equivalence ratios were similar for all fuels. The primary and secondary furnace temperatures were varied from 800 degrees C to 1000 degrees C. The effects of fuel blending, combustion staging, and operating furnace temperatures on the emissions from the two fuels were assessed. Furnace effluents were analyzed for carbon dioxide and for products of incomplete combustion (PIC) including CO, volatile and semi-volatile hydrocarbons, as well as particulate matter. Results showed that whereas CO2 was generated during both the observed sequential volatile matter and char combustion phases of the fuels, PICs were only generated during the volatile matter combustion phase. CO2 emissions were the highest from coal, whereas CO and other PIC emissions were the highest from bagasse. Under this particular combustion configuration, combustion of the volatile matter of the blends resulted in lower yields of PIC, than combustion of the volatiles of the neat fuels. Though CO and unburned hydrocarbons from coal as well as from the blends did not exhibit a clear trend with furnace temperature, such emissions from bagasse clearly increased with temperature. The presence of the secondary furnace (afterburner) typically reduced PIC, by promoting further oxidation of the primary furnace effluents. (C) 2012 Elsevier Ltd. All rights reserved.
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This work reports on emissions of unburned hydrocarbon species from batch combustion of fixed beds of coal, sugar-cane bagasse, and blends thereof in a pre-heated two-stage laboratory furnace operated in the temperature range of 800-1000 degrees C. The effects of fuel blending, combustion staging, and operating furnace temperatures on emissions of pollutants were assessed. Furnace effluents were analyzed for products of incomplete combustion (PICs) including CO, volatile and semi-volatile hydrocarbons, and particulate matter, as has been reported in Ref. [1]. Emitted unburned hydrocarbons include traces of potentially health-hazardous Polycyclic Aromatic Hydrocarbons (PAHs), which are the focus of this work. Under the batch combustion conditions implemented herein, PAH were only generated during the volatile combustion phase of the fuels. The most prevalent species were in descending order: naphthalene, acenaphthylene, phenanthrene, fluoranthene, pyrene, dibenzofuran, benzofuran, byphenyl, fluorene, 9H-fluoren-9-one, acephenantrylene, benzo[b] fluoranthene, 1-methyl-naphthalene; 2-methyl-naphthalene, benz[a] anthracene and benzo[a] pyrene. PAH yields were the highest from combustion of neat bagasse. Combustion of the blends resulted in lower yields of PAH, than combustion of either of their neat fuel constituents. Increasing the furnace operating temperature enhanced the PAH emissions from bagasse, but had little effect on those from the coal or from the blends. Flue gas treatment in a secondary-stage furnace, upon with additional air, typically reduced PAH yields by promoting oxidation of the primary-stage furnace effluents. (C) 2011 Elsevier Ltd. All rights reserved.
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We present a new method to quantify substructures in clusters of galaxies, based on the analysis of the intensity of structures. This analysis is done in a residual image that is the result of the subtraction of a surface brightness model, obtained by fitting a two-dimensional analytical model (beta-model or Sersic profile) with elliptical symmetry, from the X-ray image. Our method is applied to 34 clusters observed by the Chandra Space Telescope that are in the redshift range z is an element of [0.02, 0.2] and have a signal-to-noise ratio (S/N) greater than 100. We present the calibration of the method and the relations between the substructure level with physical quantities, such as the mass, X-ray luminosity, temperature, and cluster redshift. We use our method to separate the clusters in two sub-samples of high-and low-substructure levels. We conclude, using Monte Carlo simulations, that the method recuperates very well the true amount of substructure for small angular core radii clusters (with respect to the whole image size) and good S/N observations. We find no evidence of correlation between the substructure level and physical properties of the clusters such as gas temperature, X-ray luminosity, and redshift; however, analysis suggest a trend between the substructure level and cluster mass. The scaling relations for the two sub-samples (high-and low-substructure level clusters) are different (they present an offset, i. e., given a fixed mass or temperature, low-substructure clusters tend to be more X-ray luminous), which is an important result for cosmological tests using the mass-luminosity relation to obtain the cluster mass function, since they rely on the assumption that clusters do not present different scaling relations according to their dynamical state.
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Objective: To estimate the prevalence of anemia and analyze the factors associated with anemia in elderly residents of long-term care institutions. Methods: This cross-sectional study was performed in male and female elderly volunteers selected in a two-stage random sampling from long-term care institutions in the city of Maringa, Brazil (2008). A diagnosis of anemia was based on the plasma hemoglobin concentration. The independent variables analyzed were gender, age, time of residence at an institution, body mass index, and serum iron and albumin concentrations. The association between anemia and the variables was assessed using the Poisson regression with robust variance in unadjusted and adjusted analyses, considering a complex sample and a significance level of 5%. Results: The sample included 124 adults older than 60 y residing in long-term care institutions (53.0% female). The prevalence of anemia was 29% and was not significantly associated with gender, serum iron concentration, time of residence at an institution, or body mass index. Conversely, hypoalbuminemia was considered a risk factor for anemia. Conclusion: There is a high prevalence of anemia in the institutionalized elderly and hypoalbuminemia is a factor associated with this outcome. Interventions are necessary to promote improvements in the health and welfare of this population. (C) 2012 Published by Elsevier Inc.
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Objectives: To evaluate the effect of insertion torque on micromotion to a lateral force in three different implant designs. Material and methods: Thirty-six implants with identical thread design, but different cutting groove design were divided in three groups: (1) non-fluted (no cutting groove, solid screw-form); (2) fluted (901 cut at the apex, tap design); and (3) Blossomt (Patent pending) (non-fluted with engineered trimmed thread design). The implants were screwed into polyurethane foam blocks and the insertion torque was recorded after each turn of 901 by a digital torque gauge. Controlled lateral loads of 10N followed by increments of 5 up to 100N were sequentially applied by a digital force gauge on a titanium abutment. Statistical comparison was performed with two-way mixed model ANOVA that evaluated implant design group, linear effects of turns and displacement loads, and their interaction. Results: While insertion torque increased as a function of number of turns for each design, the slope and final values increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M +/- standard deviation [SD] = 64.1 +/- 26.8, 139.4 +/- 17.2, and 205.23 +/- 24.3 Ncm, respectively). While a linear relationship between horizontal displacement and lateral force was observed for each design, the slope and maximal displacement increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M +/- SD 530 +/- 57.7, 585.9 +/- 82.4, and 782.33 +/- 269.4 mm, respectively). There was negligible to moderate levels of association between insertion torque and lateral displacement in the Blossomt, fluted and non-fluted design groups, respectively. Conclusion: Insertion torque was reduced in implant macrodesigns that incorporated cutting edges, and lesser insertion torque was generally associated with decreased micromovement. However, insertion torque and micromotion were unrelated within implant designs, particularly for those designs showing the least insertion torque.
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Introduction: Studies designed to investigate chronic rhinosinusitis (CRS) epidemiology play an important role to assess population's distribution and risk factors to result in the development and promotion of public health policies. Method: This study design is a survey carried out with a complex two-stage cluster sampling plan. Personal interviews were carried out with 2,003 individuals. The questionnaire included the epidemiological criteria for CRS. Demographic data, history of physician-diagnosed respiratory diseases (asthma, sinusitis, rhinitis), smoking, family income, educational attainment, and household characteristics were also evaluated. Results: The overall response rate was 93.9% of the households. Mean age was 39.8 +/- 21 years; 45.33% were male. The overall prevalence of CRS in the city of Sao Paulo was 5.51%. We found a significant association between diagnosis of CRS and diagnosis of asthma and CRS and diagnosis of rhinitis and a significant association between presence of CRS and belonging to the low-income subgroup. Conclusion: The municipality of Sao Paulo has an urban population of 11 million. According to the present study, the prevalence of CRS is 5.51%, which represents more than 500,000 individuals affected by this condition in the city.
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Background and Study Aim: The grip strength endurance is important for Brazilian Jiu-Jitsu (BJJ). Thus, the aims of this study were: a) to test the reliability of two kimono grip strength tests named maximum static lift (MSL) and maximum number of repetitions (MNR) and b) to examine differences between elite and non-elite BJJ players in these tests. Material/Methods: Thirty BJJ players participated into two phases: "A" to test reliability and "B" to compare elite and non-elite. In phase A, twenty participants performed the MSL and, 15 min later, the MNR in two occasions with 24-h interval. In phase B, ten other BJJ practitioners (non-elite) and ten athletes (elite) performed the same tests. The intraclass correlation coefficient (ICC) two way fixed model (3,1), Bland-Altman plot and the limits of agreement were used to test reliability, correlation between the tests were evaluated by Pearson correlations and independent T test (P<0.05) was utilized to compare elite vs. non-elite. Results: The ICC was high for repeated measurements on different days of phase A (MSL: r=0.99 and MNR: r=0.97). Limits of agreement for time of suspension were -6.9 to 2.4-s, with a mean difference of -2.3 s (CI: -3.3 to -1.2-s), while for number of repetitions the limits of agreement were -2.9 to 2.3-rep, with a mean difference of -0.3-rep (CI: -0.9 to 0.3-rep). In phase B, elite presented better performance for both tests (P<0.05) compared to non-elite (56 +/- 10-s vs. 37 +/- 11-s in MSL and 15 +/- 4-rep vs. 8 +/- 3-rep in MNR). Moderate correlation were found between MSL and MNR for absolute values during test (r=0.475; p=0.034), and retest phases (r=0.489; p=0.029), while moderate and high correlations in the test (r=0.615; p=0.004) and retest phases (r=0.716; p=0.001) were found for relative values, respectively. Conclusions: These proposed tests are reliable and both static and dynamic grip strength endurance tests seem to differentiate BJJ athletes from different levels.