43 resultados para Linear and nonlinear methods
Resumo:
Fresh and combined methods processed Cantaloupe melons, mangoes and cashew apples were submitted to consumers' acceptance and scored on a nine-point hedonic scale. Fruits were osmotically treated in sucrose syrup with two different concentrations of SO2. Overall acceptance, appearance, aroma, flavor and texture were evaluated. Fresh cashew apples received lower scores for acceptance than processed cashew apples while fresh mangoes were more acceptable than processed mangoes. Acceptance of fresh melons and processed melons was similar. Treatments of the tropical fruits with two different concentrations of SO2 did not demonstrate significant differences between the fruits tested.
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Different methods to determine total fat (TF) and fatty acids (FA), including trans fatty acids (TFA), in diverse foodstuffs were evaluated, incorporating gravimetric methods and gas chromatography with flame ionization detector (GC/FID), in accordance with a modified AOAC 996.06 method. Concentrations of TF and FA obtained through these different procedures diverged (p< 0.05) and TFA concentrations varied beyond 20 % of the reference values. The modified AOAC 996.06 method satisfied both accuracy and precision, was fast and employed small amounts of low toxicity solvents. Therefore, the results showed that this methodology is viable to be adopted in Brazil for nutritional labeling purposes.
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A simple and sensitive spectrophotometric method is proposed for the simultaneous determination of protocatechuic acid and protocatechuic aldehyde. The method is based on the difference in the kinetic rates of the reactions of analytes with [Ag(NH3)2]+ in the presence of polyvinylpyrrolidone to produce silver nanoparticles. The data obtained were processed by chemometric methods using principal component analysis artificial neural network and partial least squares. Excellent linearity was obtained in the concentration ranges of 1.23-58.56 µg mL-1 and 0.08-30.39 µg mL-1 for PAC and PAH, respectively. The limits of detection for PAC and PAH were 0.039 and 0.025 µg mL-1, respectively.
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Nutritional status of eight 1.0 and 4.7 years old clones of Eucalyptus grandis, cultivated in a medium textured Ustults - US - and a Quartzipsamments - PS - soils, in Lençóis Paulista, São Paulo, were evaluated by the Diagnosis and Recommendation Integrated System (DRIS) and Critical Level (CL) methods. Based on multivariate discriminant analysis, the DRIS indices described the nutritional status of trees better in relation to tree age and soil type than in relation to nutrient composition. Spearman's correlation coefficients showed statistically significant relationships between volumetric tree growth and nutrients when applying DRIS indices or foliar nutrient concentrations. However, the DRIS indices indicated a lower number of trees with nutritional deficiencies, in relation to the CL method. According to the CL method, P, S, and Ca were deficient in the majority of the soils and tree age categories. By the DRIS method, Ca was the only deficient nutrient in PS soils, and appeared to be particularly limited in one-year-old trees. In conclusion, the DRIS method was more efficient than the CL method in evaluating the nutritional status of eucalyptus trees.
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The penetration resistance (PR) is a soil attribute that allows identifies areas with restrictions due to compaction, which results in mechanical impedance for root growth and reduced crop yield. The aim of this study was to characterize the PR of an agricultural soil by geostatistical and multivariate analysis. Sampling was done randomly in 90 points up to 0.60 m depth. It was determined spatial distribution models of PR, and defined areas with mechanical impedance for roots growth. The PR showed a random distribution to 0.55 and 0.60 m depth. PR in other depths analyzed showed spatial dependence, with adjustments to exponential and spherical models. The cluster analysis that considered sampling points allowed establishing areas with compaction problem identified in the maps by kriging interpolation. The analysis with main components identified three soil layers, where the middle layer showed the highest values of PR.
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Identification of Escherichia coli requires knowledge regarding the prevalent serotypes and virulence factors profiles allows the classification in pathogenic/non-pathogenic. However, some of these bacteria do not express flagellar antigen invitro. In this case the PCR-restriction fragment length polymorphism (RFLP-PCR) and sequencing of the fliC may be suitable for the identification of antigens by replacing the traditional serology. We studied 17 samples of E. coli isolated from animals and presenting antigen H nontypeable (HNT). The H antigens were characterized by PCR-RFLP and sequencing of fliC gene. Three new flagellin genes were identified, for which specific antisera were obtained. The PCR-RFLP was shown to be faster than the serotyping H antigen in E. coli, provided information on some characteristics of these antigens and indicated the presence of new genes fliC.
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Mobility of atrazine in soil has contributed to the detection of levels above the legal limit in surface water and groundwater in Europe and the United States. The use of new formulations can reduce or minimize the impacts caused by the intensive use of this herbicide in Brazil, mainly in regions with higher agricultural intensification. The objective of this study was to compare the leaching of a commercial formulation of atrazine (WG) with a controlled release formulation (xerogel) using bioassay and chromatographic methods of analysis. The experiment was a split plot randomized block design with four replications, in a (2 x 6) + 1 arrangement. The main formulations of atrazine (WG and xerogel) were allocated in the plots, and the herbicide concentrations (0, 3200, 3600, 4200, 5400 and 8000 g ha-1), in the subplots. Leaching was determined comparatively by using bioassays with oat and chromatographic analysis. The results showed a greater concentration of the herbicide in the topsoil (0-4 cm) in the treatment with the xerogel formulation in comparison with the commercial formulation, which contradicts the results obtained with bioassays, probably because the amount of herbicide available for uptake by plants in the xerogel formulation is less than that available in the WG formulation.
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In order to evaluate the resolving power of several typing methods to identify relatedness among Brazilian strains of Enterobacter cloacae, we selected twenty isolates from different patients on three wards of a University Hospital (Orthopedics, Nephrology, and Hematology). Traditional phenotyping methods applied to isolates included biotyping, antibiotic sensitivity, phage-typing, and O-serotyping. Plasmid profile analysis, ribotyping, and macrorestriction analysis by pulsed-field gel electrophoresis (PFGE) were used as genotyping methods. Sero- and phage-typing were not useful since the majority of isolates could not be subtyped by these methods. Biotyping, antibiogram and plasmid profile permitted us to classify the samples into different groups depending on the method used, and consequently were not reliable. Ribotyping and PFGE were significantly correlated with the clinical epidemiological analysis. PFGE did not type strains containing nonspecific DNase. Ribotyping was the most discriminative method for typing Brazilian isolates of E. cloacae.
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Methods for reliable evaluation of spinal cord (SC) injury in rats at short periods (2 and 24 h) after lesion were tested to characterize the mechanisms implicated in primary SC damage. We measured the physiological changes occurring after several procedures for producing SC injury, with particular emphasis on sensorimotor functions. Segmental and suprasegmental reflexes were tested in 39 male Wistar rats weighing 250-300 g divided into three control groups that were subjected to a) anesthesia, b) dissection of soft prevertebral tissue, and c) laminectomy of the vertebral segments between T10 and L1. In the lesion group the SC was completely transected, hemisected or subjected to vertebral compression. All animals were evaluated 2 and 24 h after the experimental procedure by the hind limb motility index, Bohlman motor score, open-field, hot-plate, tail flick, and paw compression tests. The locomotion scale proved to be less sensitive than the sensorimotor tests. A reduction in exploratory movements was detected in the animals 24 h after the procedures. The hot-plate was the most sensitive test for detecting sensorimotor deficiencies following light, moderate or severe SC injury. The most sensitive and simplest test of reflex function was the hot-plate. The hemisection model promoted reproducible moderate SC injury which allowed us to quantify the resulting behavior and analyze the evolution of the lesion and its consequences during the first 24 h after injury. We conclude that hemisection permitted the quantitation of behavioral responses for evaluation of the development of deficits after lesions. Hind limb evaluation scores and spontaneous exploration events provided a sensitive index of immediate injury effects after SC lesion at 2 and 24 h. Taken together, locomotion scales, open-field, and hot-plate tests represent reproducible, quantitatively sensitive methods for detecting functional deficiencies within short periods of time, indicating their potential for the study of cellular mechanisms of primary injury and repair after traumatic SC injury.
Differential effects of aging on spatial contrast sensitivity to linear and polar sine-wave gratings
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Changes in visual function beyond high-contrast acuity are known to take place during normal aging. We determined whether sensitivity to linear sine-wave gratings and to an elementary stimulus preferentially processed in extrastriate areas could be distinctively affected by aging. We measured spatial contrast sensitivity twice for concentric polar (Bessel) and vertical linear gratings of 0.6, 2.5, 5, and 20 cycles per degree (cpd) in two age groups (20-30 and 60-70 years). All participants were free of identifiable ocular disease and had normal or corrected-to-normal visual acuity. Participants were more sensitive to Cartesian than to polar gratings in all frequencies tested, and the younger adult group was more sensitive to all stimuli tested. Significant differences between sensitivities of the two groups were found for linear (only 20 cpd; P<0.01) and polar gratings (all frequencies tested; P<0.01). The young adult group was significantly more sensitive to linear than to circular gratings in the 20 cpd frequency. The older adult group was significantly more sensitive to linear than to circular gratings in all spatial frequencies, except in the 20 cpd frequency. The results suggest that sensitivity to the two kinds of stimuli is affected differently by aging. We suggest that neural changes in the aging brain are important determinants of this difference and discuss the results according to current models of human aging.
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Understanding the effects of radiation and its possible influence on the nervous system are of great clinical interest. However, there have been few electrophysiological studies on brain activity after exposure to ionizing radiation (IR). A new methodological approach regarding the assessment of the possible effects of IR on brain activity is the use of linear and nonlinear mathematical methods in the analysis of complex time series, such as brain oscillations measured using the electrocorticogram (ECoG). The objective of this study was to use linear and nonlinear mathematical methods as biomarkers of gamma radiation regarding cortical electrical activity. Adult Wistar rats were divided into 3 groups: 1 control and 2 irradiated groups, evaluated at 24 h (IR24) and 90 days (IR90) after exposure to 18 Gy of gamma radiation from a cobalt-60 radiotherapy source. The ECoG was analyzed using power spectrum methods for the calculation of the power of delta, theta, alpha and beta rhythms and by means of the α-exponent of the detrended fluctuation analysis (DFA). Using both mathematical methods it was possible to identify changes in the ECoG, and to identify significant changes in the pattern of the recording at 24 h after irradiation. Some of these changes were persistent at 90 days after exposure to IR. In particular, the theta wave using the two methods showed higher sensitivity than other waves, suggesting that it is a possible biomarker of exposure to IR.
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This paper was designed to evaluate the rancidity of 18 pet food samples using the Diamed FATS kits and official AOCS methods for the quantification of free fatty acids, peroxide value and concentrations of malonaldehyde and alkenal in the lipid extracted. Although expiration dates have passed, the samples presented good quality evidencing little oxidative rancidity. The results of this study suggest that the Brazilian pet food market is replete with products of excellent quality due to the competitiveness of this market sector.
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A reversed-phase liquid chromatographic (LC) and ultraviolet (UV) spectrophotometric methods were developed and validated for the assay of bromopride in oral and injectable solutions. The methods were validated according to ICH guideline. Both methods were linear in the range between 5-25 μg mL-1 (y = 41837x - 5103.4, r = 0.9996 and y = 0.0284x - 0.0351, r = 1, respectively). The statistical analysis showed no significant difference between the results obtained by the two methods. The proposed methods were found to be simple, rapid, precise, accurate, and sensitive. The LC and UV methods can be used in the routine quantitative analysis of bromopride in oral and injectable solutions.
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OBJECTIVE To examine factors associated with social participation and their relationship with self-perceived well-being in older adults. METHODS This study was based on data obtained from the National Socioeconomic Characterization (CASEN) Survey conducted in Chile, in 2011, on a probability sample of households. We examined information of 31,428 older adults living in these households. Descriptive and explanatory analyses were performed using linear and multivariate logistic regression models. We assessed the respondents’ participation in different types of associations: egotropic, sociotropic, and religious. RESULTS Social participation increased with advancing age and then declined after the age of 80. The main finding of this study was that family social capital is a major determinant of social participation of older adults. Their involvement was associated with high levels of self-perceived subjective well-being. We identified four settings as sources of social participation: home-based; rural community-based; social policy programs; and religious. Older adults were significantly more likely to participate when other members of the household were also involved in social activities evidencing an intergenerational transmission of social participation. Rural communities, especially territorial associations, were the most favorable setting for participation. There has been a steady increase in the rates of involvement of older adults in social groups in Chile, especially after retirement. Religiosity remains a major determinant of associativism. The proportion of participation was higher among older women than men but these proportions equaled after the age of 80. CONCLUSIONS Self-perceived subjective well-being is not only dependent upon objective factors such as health and income, but is also dependent upon active participation in social life, measured as participation in associations, though its effects are moderate.
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This study aims to assess the association between schistosomiasis and hookworm infection with hemoglobin levels of schoolchildren in northern Mozambique. Through a cross-sectional survey, 1,015 children from five to 12 years old in the provinces of Nampula, Cabo Delgado and Niassa were studied. Hookworm infection and urinary schistosomiasis were diagnosed, through Ritchie and filtration methods, with a prevalence of 31.3% and 59.1%, respectively. Hemoglobin levels were obtained with a portable photometer (Hemocue®). The average hemoglobin concentration was 10.8 ± 1.42 g/dL, and 62.1% of the children presented levels below 11.5 g/dL, of which 11.8% of the total number of children had hemoglobin levels below 9 g/dL. A multiple linear regression analysis demonstrated negative interactions between hemoglobin levels and ancylostomiasis, this being restricted to the province of Cabo Delgado (β = -0.55; p < 0.001) where an independent interaction between hemoglobin levels and urinary schistosomiasis was also observed (β = -0.35; p = 0.016). The logistical regression model indicated that hookworm infection represents a predictor of mild (OR = 1.87; 95% CI = 1.17-3.00) and moderate/severe anemia (OR = 2.71; 95% CI = 1.50 - 4.89). We concluded that, in the province of Cabo Delgado, hookworm and Schistosoma haematobium infections negatively influence hemoglobin levels in schoolchildren. Periodical deworming should be considered in the region. Health education and improvements in sanitary infrastructure could achieve long-term and sustainable reductions in soil-transmitted helminthiases and schistosomiasis prevalence rates.