964 resultados para VO(2)PEAK


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Interstitial solutes in body-centered cubic metals, such as oxygen in tantalum, produce ideally Snoek effects when they are in solutions enough diluted. However, for higher concentration of these solutes, more complex relaxation process can occur, as interaction between interstitial solutes and dislocations. Anelastic relaxation measurements were carried out in polycrystalline tantalum samples, using torsion pendulum inverted, operating between 300 K and 680 K and oscillation frequencies in the hertz bandwidth, for three different experimental sample conditions: as received sample, annealed and annealed followed by a treatment in an oxygen atmosphere. These measurements have revealed the following behavior: the intensity of the internal friction peak associated to matrix-interstitial interaction Ta-O decreased between the first run and the next runs, and this phenomenon did not occur for the others conditions. The variation of relaxation strength of Ta-O peak, with number of runs is due to a decrease of an amount of oxygen in solid solution, which can be associated with the precipitation of new phases in Ta sample and with the trapping of oxygen atoms by dislocations.

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This study aimed to determine the influence of flexibility of the chair seat surface on the pressure peak and on the contact area during the execution of a task of handling an object on the seated position by individuals with spastic cerebral palsy. Ten individuals of both genders with diagnosis of spastic cerebral palsy, who had some control to voluntarily move the body and the upper limbs, participated in this study. Quantification of data was carried out in two experimental situations: (1) execution of a task of fitting with upper limbs, and with the individual placed on an adapted canvas seat; (2) execution of a task of fitting with the participant positioned on an adapted wooden seat. Data obtained were submitted to a non-parametric and descriptive statistical analysis using the Wilcoxon test. Results indicated that the use of canvas seat increased the contact area and decreased the pressure peak and the medio-lateral displacement of centre pressure on the seated posture. © 2011 Informa UK, Ltd.

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The gerbil female prostate undergoes morphological and physiological changes resulting from hormonal fluctuations that occur during the reproductive cycle. These repetitive cycles of glandular growth and regression are followed by an extensive reconstruction and remodeling of prostate stroma throughout the reproductive life of the female gerbil. The objective of this study was to evaluate the effect that the hormonal fluctuations of the reproductive cycle have on the stromal remodeling and the expression and activity of matrix metalloproteinases MMP-2 and -9 in the adult female gerbil prostate. For this, serological, ultrastructural, immunohistochemical and biochemical methods were employed. The results showed that the major stromal alteration coincide with the peak of estradiol, which occurs in estrus, and with the peak of progesterone, occurring during diestrus II. MMP-2 and -9 presented a similar pattern of expression and activity during estrous cycle. The estrus was the phase of greater expression and activity of MMP-2 and -9. On the other hand, in DI and DII, the tissue expression and activity of MMP-2 and -9 was very weak. These results are important since they suggest the involvement of estradiol and progesterone in regulating the expression and activity of MMP-2 and -9 in adult gerbil female prostate. © 2011 Elsevier Inc.

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This study investigated GH secretion after clonidine (alpha-2 adrenergic agonist) treatment in pre-pubertal Nelore heifers. Clonidine (10 mg/kg, IV, 15 min samples for 4 h) was administrated in the same Nelore heifers at eight (n = 4), 12 (n = 5) and 15 (n = 4) months of age. The GH concentration was measured by radioimmunoassay (sensivity = 0.25 ng/mL, CV = 16%). At eight months, clonidine increased GH average concentration, total area of peaks, the total area of GH secretion and increased peak amplitude and reduced time to onset of peak (P < 0.05). At 15 months, the administration of clonidine increased the GH average concentration and at 12 months the increased occurred only in restricted intervals (P < 0.05). Clonidine injection stimulated GH secretion in prepubertal heifers and this effect was more evident in Nelore heifers at eight months compared to 12 and 15 months of age.

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Purpose. Isokinetic tests are often applied to assess muscular strength and EMG activity, however the specific ranges of motion used in testing (fully flexed or extended positions) might be constrictive and/or be painful for patients with injuries or under-going rehabilitation. The aim of this study was to examine the effects of different ranges of motion (RoM) when determining maximal EMG during isokinetic knee flexion and extension with different types of contractions and velocities. Methods. Eighteen males had EMG activity recorded on the vastus lateralis, vastus medialis, semitendinosus and biceps femoris muscles during five maximal isokinetic concentric and eccentric contractions for the knee flexors and extensors at 60° • s -1 and 180° • s -1. The root mean square of EMG was calculated at three different ranges of motion: (1) a full range of motion (90°-20° [0° = full knee extension]); (2) a range of motion of 20° (between 60°-80° and 40°-60° for knee extension and flexion, respectively) and (3) at a 10° interval around the angle where peak torque is produced. EMG measurements were statistically analyzed (ANOVA) to test for the range of motion, contraction velocity and contraction speed effects. Coefficients of variation and Pearson's correlation coefficients were also calculated among the ranges of motion. Results. Predominantly similar (p > 0.05) and well-correlated EMG results (r > 0.7, p ≤ 0.001) were found among the ranges of motion. However, a lower coefficient of variation was found for the full range of motion, while the 10° interval around peak torque at 180° • s -1 had the highest coefficient, regardless of the type of contraction. Conclusions. Shorter ranges of motion at around the peak torque angle provides a reliable indicator when recording EMG activity during maximal isokinetic parameters. It may provide a safer alternative when testing patients with injuries or undergoing rehabilitation.

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Introduction. In this study we aimed to evaluate the peak cough flow (PCF) in healthy Brazilian subjects. Methods. We evaluated 484 healthy subjects between 18 and 40 years old. Subjects were seated and oriented were asked to perform a maximal inspiration followed by a quick, short and explosive expiration on the peak flow meter. Three measures were carried out and recorded the average of the three results for each individual. Results: The PCF values ranged between 240 and 500 L/min. The PCF values were lower in females than in males. The PCF was inversely proportional to age. Conclusion: The values for Brazilian adult healthy subjects regarding PCF were between 240 and 500 L/min. © 2012 Cardoso et al.; licensee BioMed Central Ltd.

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The maximal oxygen uptake (VO2max) is the maximal quantity of energy that can be produced by the aerobic metabolism in certain time unity. It can be determined direct or indirectly by predictive equations. The objective of this study was to make a specific predictive equation to determine the VO 2max from boys aged 10-16 years-old. Forty-two boys underwent a treadmill running ergospirometric test, with the initial velocity set at 9 km/h, until voluntary exhaustion. By the multiple linear regression was possible to develop the following equation for the indirect determination of the VO 2max: VO2max (ml/min) = -1574.06 + (141.38 x Vpeak) + (48.34 * Body mass), with standard error of estimate = 191.5 ml/min (4.10 ml/kg/min) and coefficient of determination = 0.934. We suggest that this formula is appropriate to predict VO2max for this population.

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The use of chemical preservative compounds is common in the food products industry. Caramel color is the most usual additive used in beverages, desserts, and breads worldwide. During its fabrication process, 2- and 4-methylimidazole (MeI), highly carcinogenic compounds, are generated. In these cases, the development of reliable analytical methods for the monitoring of undesirable compounds is necessary. The primary procedure for the analysis of 2- and 4-MeI is using LC- or GC-MS techniques. These procedures are time-consuming and require large amounts of organic solvents and several pretreatment steps. This prevents the routine use of this procedure. This paper describes a rapid, efficient, and simple method using capillary electrophoresis (CE) for the separation and determination of 2- and 4-MeI in caramel colors. The analyses were performed using a 75 μm i.d. uncoated fused-silica capillary with an effective length of 40 cm and a running electrolyte consisting of 160 mmol L-1 phosphate plus 30% acetonitrile. The pH was adjusted to 2.5 with triethylamine. The analytes were separated within 6 min at a voltage of 20 kV. Method validation revealed good repeatability of both migration time (<0.8% RSD) and peak area (<2% RSD). Analytical curves for 2- and 4-MeI were linear in the 0.4-40 mg L-1 concentration interval. Detection limits were 0.16 mg L-1 for 4-MeI and 0.22 mg L-1 for 2-MeI. The extraction recoveries were satisfactory. The developed method showed many advantages when compared to the previously used method. © 2013 American Chemical Society.

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It is presented a software developed with Delphi programming language to compute the reservoir's annual regulated active storage, based on the sequent-peak algorithm. Mathematical models used for that purpose generally require extended hydrological series. Usually, the analysis of those series is performed with spreadsheets or graphical representations. Based on that, it was developed a software for calculation of reservoir active capacity. An example calculation is shown by 30-years (from 1977 to 2009) monthly mean flow historical data, from Corrente River, located at São Francisco River Basin, Brazil. As an additional tool, an interface was developed to manage water resources, helping to manipulate data and to point out information that it would be of interest to the user. Moreover, with that interface irrigation districts where water consumption is higher can be analyzed as a function of specific seasonal water demands situations. From a practical application, it is possible to conclude that the program provides the calculation originally proposed. It was designed to keep information organized and retrievable at any time, and to show simulation on seasonal water demands throughout the year, contributing with the elements of study concerning reservoir projects. This program, with its functionality, is an important tool for decision making in the water resources management.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)