953 resultados para Independent variables
Resumo:
Thyroid diseases are common, and use of levothyroxine is increasing worldwide. We investigated the influence of gender, race and socioeconomic status on the diagnosis and treatment of thyroid disorders using data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), a multicenter cohort study of civil servants (35-74 years of age) from six Brazilian cities. Diagnosis of thyroid dysfunction was by thyrotropin (TSH), and free thyroxine (FT4) if TSH was altered, and the use of specific medications. Multivariate logistic regression models were constructed using overt hyperthyroidism/hypothyroidism and levothyroxine use as dependent variables and sociodemographic characteristics as independent variables. The frequencies of overt hyper- and hypothyroidism were 0.7 and 7.4%, respectively. Using whites as the reference ethnicity, brown, and black race were protective for overt hypothyroidism (OR=0.76, 95%CI=0.64-0.89, and OR=0.53, 95%CI=0.43-0.67, respectively, and black race was associated with overt hyperthyroidism (OR=1.82, 95%CI=1.06-3.11). Frequency of hypothyroidism treatment was higher in women, browns, highly educated participants and those with high net family incomes. After multivariate adjustment, levothyroxine use was associated with female gender (OR=6.06, 95%CI=3.19-11.49) and high net family income (OR=3.23, 95%CI=1.02-10.23). Frequency of hyperthyroidism treatment was higher in older than in younger individuals. Sociodemographic factors strongly influenced the diagnosis and treatment of thyroid disorders, including the use of levothyroxine.
Resumo:
Rice flour was processed by extrusion cooking in the presence of variable contents of water and sucrose. The process was carried out in a twin-screw extruder under the conditions given by a centre rotational experimental design of second order. The effects of the independent variables, water content (27.9 to 42.1%), and sucrose content (0.1 to 19.9%) on the physicochemical properties of the extrudates were investigated. The water absorption index (WAI), water solubility index (WSI), volumetric expansion index (VEI), and bulk density (BD) were determined as dependent variables. BD was determined for samples before and after frying. An increase in water contents resulted in higher WAI and VEI, and lower WSI and BD for extrudates before and after frying. Higher sucrose levels led to increased values of WAI and VEI and to reduced values of WSI and BD. Both independent variables had significant influence on the physicochemical properties of rice flour extrudates. However, the sucrose content was the most significant. The interaction between these two independent variables and their quadratic effect were also important for the responses studied.
Resumo:
In this work, the effects of thermoplastic extrusion process parameters (raw material moisture content and temperature) and the addition of functional ingredients (lycopene and soy protein) on quality characteristics of a base-formulation for extruded corn snacks were studied, with the objective of developing an easy-to-eat functional product. A single-screw Labor PQ 30 model Inbramaq extruder was used for extrusion and a central composite rotational design (CCRD) was followed. The independent variables were: i) percentage of soy protein isolate (0-30%); ii) percentage of lycopene preparation (0-0.1%); iii) raw material moisture content (20-30%); and iv) 5th zone temperature (100-150 °C). The expansion index reached maximum values with the lowest raw material moisture content (20%) and intermediate temperatures (approximately 125 °C). Instrumental hardness was higher with high moisture and low temperature; however, increasing the percentage of soy protein was beneficial for the texture of the product, reducing hardness. The red color intensity increased with the increase in lycopene content and moisture, and with the reduction of temperature. Sensory acceptance tests were carried out for two products, with maximum percentages of the functional ingredients, 20% moisture and temperatures of 125 and 137 °C, with greater acceptance for the product extruded at 125 °C.
Resumo:
The aim of this study was to determine the influence of process parameters and Passion Fruit Fiber (PFF) addition on the Glycemic Index (GI) of an extruded breakfast cereal. A 2³ Central Composite Rotational Design (CCRD) was used, with the following independent variables: raw material moisture content (18-28%), 2nd and 3rd barrel zone temperatures (120-160 ºC), and PFF (0-30%). Raw materials (organic corn flour and organic PFF) were characterized as to their proximate composition, particle size, and in vitro GI. The extrudates were characterized as to their in vitro GI. The Response Surface Methodology (RSM) and Principal Component Analysis (PCA) were used to analyze the results. Corn flour and PFF presented 8.55 and 7.63% protein, 2.61 and 0.60% fat, 0.52 and 6.17% ash, 78.77 and 78.86% carbohydrates (3 and 64% total dietary fiber), respectively. The corn flour particle size distribution was homogeneous, while PFF presented a heterogeneous particle size distribution. Corn flour and PFF presented values of GI of 48 and 45, respectively. When using RSM, no effect of the variables was observed in the GI of the extrudates (average value of 48.41), but PCA showed that the GI tended to be lower when processing at lower temperatures (<128 ºC) and at higher temperatures (>158 ºC). When compared to white bread, the extrudates showed a reduction of the GI of up to 50%, and could be considered an interesting alternative in weight and glycemia control diets.
Resumo:
Response Surface Methodology (RSM) was applied to evaluate the chromatic features and sensory acceptance of emulsions that combine Soy Protein (SP) and red Guava Juice (GJ). The parameters analyzed were: instrumental color based on the coordinates a* (redness), b* (yellowness), L* (lightness), C* (chromaticity), h* (hue angle), visual color, acceptance, and appearance. The analyses of the results showed that GJ was responsible for the high measured values of red color, hue angle, chromaticity, acceptance, and visual color, whereas SP was the variable that increased the yellowness intensity of the assays. The redness (R²adj = 74.86%, p < 0.01) and hue angle (R²adj = 80.96%, p < 0.01) were related to the independent variables by linear models, while the sensory data (color and acceptance) could not be modeled due to a high variability. The models of yellowness, lightness, and chromaticity did not present lack of fit but presented adjusted determination coefficients bellow 70%. Notwithstanding, the linear correlations between sensory and instrumental data were not significant (p > 0.05) and low Pearson coefficients were obtained. The results showed that RSM is a useful tool to develop soy-based emulsions and model some chromatic features of guava-based emulsions through RSM.
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Cajá-manga, also known as golden apple and hog-plum, is an exotic fruit native from Îles de la Société (French Polynesia), which was first introduced in Brazil in 1985. The pulp of ripe fruit was treated with the commercial enzymatic pool and its effect was evaluated in terms of yield, as well as the physical properties viscosity, turbidity and color (L* values). Response surface methodology was used and three levels were adopted for the independent variables temperature (30, 40, and 50 ºC), incubation time (30, 60 and 90 minutes) and enzyme concentration (0.01, 0.05, 0.09 v/v%). A central composite statistical design was used to guide the experimental work. The enzyme treatment highly increased both juice yield (up to 56%) and color (up to 8.6%) and strongly decreased viscosity (up to 57.4%), clarity (up to 77%) and turbidity (up to 85.5%). Incubation time was the most interacting facto, whereas temperature was the least one. Optimization analysis was carried out to reduce enzyme concentration to a minimum by superposing the contour plots of the tested properties, and the recommended ranges of the variables enzyme concentration, process temperature and incubation time were, respectively, 0.042-0.068%, 47.0-49.0 ºC and 82-90 minutes.
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In this study, water uptake by poultry carcasses during cooling by water immersion was modeled using artificial neural networks. Data from twenty-five independent variables and the final mass of the carcass were collected in an industrial plant to train and validate the model. Different network structures with one hidden layer were tested, and the Downhill Simplex method was used to optimize the synaptic weights. In order to accelerate the optimization calculus, Principal Component Analysis (PCA) was used to preprocess the input data. The obtained results were: i) PCA reduced the number of input variables from twenty-five to ten; ii) the neural network structure 4-6-1 was the one with the best result; iii) PCA gave the following order of importance: parameters of mass transfer, heat transfer, and initial characteristics of the carcass. The main contributions of this work were to provide an accurate model for predicting the final content of water in the carcasses and a better understanding of the variables involved.
Resumo:
The objective of the present work was to evaluate the capacity of three isolates of Aspergillus flavus to produce aflatoxin under different culture conditions. This experiment was based on a 2³ factorial design, in which the independent variables were temperature (20-40 °C), incubation time (7-21 days), and the pH (2.0-6.0) in two different synthetic media. The optimal conditions were applied to non-aflatoxigenic isolates previously tested in coconut agar. Aflatoxin B1 was extracted directly from the synthetic cultures with chloroform. Thin Layer Chromatography (TLC) and Photographic Photometry were utilized to identify and quantify the compounds. Preliminary results showed that YES agar was an alternative medium for detecting the toxigenic potential of Aspergillus flavus in the following conditions: pH of 5.2, temperature of 25 °C, and incubation time of 11 days producing 206.05 ng.CFU-1 of aflatoxin B1. Of the 30 non-aflatoxigenic isolates, 12 presented a positive result in the optimal media and conditions tested.
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The aim of this work was to make tofu from soybean cultivar BRS 267 under different processing conditions in order to evaluate the influence of each treatment on the product quality. A fractional factorial 2(5-1) design was used, in which independent variables (thermal treatment, coagulant concentration, coagulation time, curd cutting, and draining time) were tested at two different levels. The response variables studied were hardness, yield, total solids, and protein content of tofu. Polynomial models were generated for each response. To obtain tofu with desirable characteristics (hardness ~4 N, yield 306 g tofu.100 g-1 soybeans, 12 g proteins.100 g-1 tofu and 22 g solids.100 g-1 tofu), the following processing conditions were selected: heating until boiling plus 10 minutes in water bath, 2% dihydrated CaSO4 w/w, 10 minutes coagulation, curd cutting, and 30 minutes draining time.
Resumo:
A blend of 50% Potato Starch (PS), 35% Quality Protein Maize (QPM), and 15% Soybean Meal (SM) were used in the preparation of expanded pellets utilizing a laboratory extruder with a 1.5 × 20.0 × 100.0 mm die-nozzle. The independent variables analyzed were Barrel Temperature (BT) (75-140 °C) and Feed Moisture (FM) (16-30%). The effect of extrusion variables was investigated in terms of Expansion Index (EI), apparent density (ApD), Penetration Force (PF) and Specific Mechanical Energy (SME), viscosity profiles, DSC, crystallinity by X-ray diffraction, and Scanning Electronic Microscopy (SEM). The PF decreased from 30 to 4 kgf with the increase of both independent variables (BT and FM). SME was affected only by FM, and decreased with the increase in this variable. The optimal region showed that the maximum EI was found for BT in the range of 123-140 °C and 27-31% for FM, respectively. The extruded pellets obtained from the optimal processing region were probably not completely degraded, as shown in the structural characterization. Acceptable expanded pellets could be produced using a blend of PS, QPM, and SM by extrusion cooking.
Resumo:
The objective of this study was to obtain babassu coconut milk powder microencapsulated by spray drying process using gum Arabic as wall material. Coconut milk was extracted by babassu peeling, grinding (with two parts of water), and vacuum filtration. The milk was pasteurized at 85 ºC for 15 minutes and homogenized to break up the fat globules, rendering the milk a uniform consistency. A central composite rotatable design with a range of independent variables was used: inlet air temperature in the dryer (170-220 ºC) and gum Arabic concentration (10-20%, w/w) on the responses: moisture content (0.52-2.39%), hygroscopicity (6.98-9.86 g adsorbed water/100g solids), water activity (0.14-0.58), lipid oxidation (0.012-0.064 meq peroxide/kg oil), and process yield (20.33-30.19%). All variables influenced significantly the responses evaluated. Microencapsulation was optimized for maximum process yield and minimal lipid oxidation. The coconut milk powder obtained at optimum conditions was characterized in terms of morphology, particle size distribution, bulk and absolute density, porosity, and wettability.
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The goal of this study was to determine the chemical composition of cashew apples agro-industrial residue and optimize the process of polyphenols extraction in this residue. The extraction process conditions were defined using a 24-1 fractional factorial experimental design using acetone and methanol as solvents. The independent variables were: time (30 to 90 min), temperature (30 to 50 °C), solvent concentrations (50% to 90%), agitation speed (100 to 300 rpm); the dependent variables were: total phenolic content and DPPH scavenging capacity. The optimized process was carried out by applying the Central Composite Rotational Design (CCRD) considering the results obtained with the 24-1 fractional factorial experimental design. The residue presented bioactive compounds in its composition, with emphasis on the content of total phenolic compounds (1975.64 mg/ 100 g). The extraction process was not affected by methanol; however, acetone affected the amounts of extracted phytochemicals. Extracts with high levels of polyphenols and strong DPPH scavenging capacity (> 80%) were obtained using 55% acetone, 30 minutes, 30 °C, and 150 rpm. The results showed that cashew apple residue is a potential natural source of bioactive compounds with strong antioxidant capacity. These compounds could be used partially or totally to replace synthetic antioxidants.
Resumo:
INTRODUCTION: Enhanced inflammatory-oxidative status is well established in chronic kidney disease. OBJECTIVE: The objective of this study was to evaluate the oxidative- inflammatory status and iron indices in patients undergoing maintenance hemodialysis (HD) with serum ferritin lower than 500ng/mL, and to correlate them with nutritional status. METHOD: In a cross-sectional survey 35 HD patients (23 with normal nutritional status, 12 with Protein-Energy-Wasting syndrome, PEW), and healthy volunteers (n = 35) were studied. Serum concentration of iron, ferritin, transferrin saturation, malondialdehyde (MDA), protein carbonyl (PC), high-sensitive serum C -reactive protein (hs-CRP) and blood counts were determined. The nutritional status was determined by anthropometric and biochemical criteria. RESULTS: HD patients showed low values of hemoglobin and higher values of ferritin, MDA and PC when compared with healthy volunteers. HD subjects with PEW had higher values of PC and hs-PCR as compared to HD patients with normal nutritional status. A multiple logistic regression analysis showed that the independent variables PC (Wald Statistic 4.25, p = 0.039) and hs-CRP (Wald Statistic 4.83, p = 0.028) where related with the patients' nutritional condition. CONCLUSION: In HD patients with serum ferritin below 500 ng/mL was observed one association of the markers of oxidative stress and inflammation with poor nutritional status independently of serum ferritin, gender and age.
Resumo:
The following study was a secondary analysis of data drawn from adolescents in South Western Ontario. The purpose of the study was to: examine the relationships among substance use and school outcomes, explore the relationships between gender and school outcomes, examine the moderating potential of gender on the substance useschool outcomes relationship, and to provide researchers and educators further knowledge of adolescent substance use behaviours. Many previous studies have failed to include the three most common substances used by adolescents (i.e., alcohol, tobacco, and marijuana). Furthermore, many studies have included only one school outcome instead of comparing several outcome variables. Moderated hierarchical regression was used to determine if gender moderated the substance use-school outcomes relationships. The dependent variables consisted of alcohol use, binge drinking, tobacco use, and marijuana use. Five measure of school outcomes were used as independent variables, including Grade Point Average, Positive School-role Behaviour, Negative School Behaviour, School Withdrawal, and School Misbehaviour. The results for this study indicated that substance use and gender were both predictors of all school outcome variables. Furthermore, gender was found to moderate 5 of the 25 substance use-school outcome relationships.
Resumo:
Despite the confimied health benefits of exercise during the postpartum period, many new mothers are not sufficiently active. The present research aimed to examine the effectiveness of 2 types of messages on intention to exercise after giving birth on 2 groups of pregnant women (low and high self-monitors) using the Theory of Planned Behavior as a theoretical basis. Participants were 2 1 8 pregnant women 1 8 years of age and older (Mean age = 27.9 years, SD = 5.47), and in their second or third trimester. Women completed a demographics questionnaire, a self-monitoring (SM) scale and the Godin Leisure Time Exercise Questionnaire for current and pre-pregnancy exercise levels. They then read one of two brochures, describing either the health or appearance benefits of exercise for postpartum women. Women's attitudes, social norms, perceived behavioral control, and intentions to exercise postpartum were then assessed to determine whether one type of message (health or appearance) was more effective for each group. A MANOVA found no significant effect (p>0.05) for message type, SM, or their interaction. Possible reasons include the fact that the two messages may have been too similar, reading any message about exercise may result in intentions to exercise, or lack of attention given to the brochure. Given the lack of research in this area, more studies are necessary to confirm the present results. Two additional exploratory analyses were conducted. Pearson correlations found higher levels of pre-pregnancy exercise and current exercise to be associated with more positive attitudes, more positive subjective norms, higher perceived behavioral control, and higher intention to exercise postpartum. A hierarchical regression was conducted to determine the predictive utility of attitudes, subjective norms, and perceived behavioral control on intention for each self-monitoring group. Results of the analysis demonstrated the three independent variables significantly predicted intention (p < .001) in both groups, accounting for 58-62% of the variance in intention. For low self-monitors, attitude was the strongest predictor of intention, followed by perceived behavioral control and subjective norm. For high self-monitors, perceived behavioral control was the strongest predictors, followed by attitudes and subjective norm. The present study has practical and real world implications by contributing to our understanding of what types of messages, in a brochure format, are most effective in changing pregnant women's attitudes, subjective norm, perceived behavioral control and intention to exercise postpartum and provides ftirther support for the use of the Theory of Planned Behavior with this population.