861 resultados para Maximal functions


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In this paper, the fuzzy Lyapunov function approach is considered for stabilizing continuous-time Takagi-Sugeno fuzzy systems. Previous linear matrix inequality (LMI) stability conditions are relaxed by exploring further the properties of the time derivatives of premise membership functions and by introducing a slack LMI variable into the problem formulation. The stability results are thus used in the state feedback design which is also solved in terms of LMIs. Numerical examples illustrate the efficiency of the new stabilizing conditions presented. © 2011 IFAC.

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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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Objective. The aim of this study was to verify the possibility of lactate minimum (LM) determination during a walking test and the validity of such LM protocol on predicting the maximal lactate steady-state (MLSS) intensity. Design. Eleven healthy subjects (24.2 ± 4.5 yr; 74.3 ± 7.7 kg; 176.9 ± 4.1 cm) performed LM tests on a treadmill, consisting of walking at 5.5 km h -1 and with 20-22% of inclination until voluntary exhaustion to induce metabolic acidosis. After 7 minutes of recovery the participants performed an incremental test starting at 7% incline with increments of 2% at each 3 minutes until exhaustion. A polynomial modeling approach (LMp) and a visual inspection (LMv) were used to identify the LM as the exercise intensity associated to the lowest [bLac] during the test. Participants also underwent to 24 constant intensity tests of 30 minutes to determine the MLSS intensity. Results. There were no differences among LMv (12.6 ± 1.7 %), LMp (13.1 ± 1.5 %), and MLSS (13.6 ± 2.1 %) and the Bland and Altman plots evidenced acceptable agreement between them. Conclusion. It was possible to identify the LM during walking tests with intensity imposed by treadmill inclination, and it seemed to be valid on identifying the exercise intensity associated to the MLSS. Copyright © 2012 Guilherme Morais Puga et al.

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Includes bibliography

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Includes bibliography

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Aim: The objective of the present study was to investigate the effect of a multimodal exercise intervention on frontal cognitive functions and kinematic gait parameters in patients with Alzheimer's disease. Methods: A sample of elderly patients with Alzheimer's disease (n=27) were assigned to a training group (n=14; aged 78.0±7.3years) and a control group (n=13; aged 77.1±7.4years). Multimodal exercise intervention includes motor activities and cognitive tasks simultaneously. The participants attended a 1-h session three times a week for 16weeks, and the control participants maintained their regular daily activities during the same period. The frontal cognitive functions were evaluated using the Frontal Assessment Battery, the Clock Drawing Test and the Symbol Search Subtest. The kinematic parameters of gait-cadence, stride length and stride speed were analyzed under two conditions: (i) free gait (single task); and (ii) gait with frontal cognitive task (walking and counting down from 20 - dual task). Results and discussion: The patients in the intervention group significantly increased the scores in frontal cognitive variables, Frontal Assessment Battery (P<0.001) and Symbol Search Subtest (P<0.001) after the 16-week period. The control group decreased the scores in the Clock Drawing Test (P=0.001) and increased the number of counting errors during the dual task (P=0.008) after the same period. Conclusion: The multimodal exercise intervention improved the frontal cognitive functions in patients with Alzheimer's disease. © 2012 Japan Geriatrics Society.

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This study was undertaken to characterize the effects of monotonous training at lactate minimum (LM) intensity on aerobic and anaerobic performances; glycogen concentrationsin the soleus muscle, the gastrocnemius muscle and the liver; and creatine kinase (CK), free fatty acids and glucose concentrations in rats. The rats were separated into trained (n =10), baseline (n = 10) and sedentary (n=10) groups. The trained group was submitted to the following: 60 min/day, 6 day/week and intensity equivalent to LM during the 12-week training period. The training volume was reduced after four weeks according to a sigmoid function. The total CK (U/L) increased in the trained group after 12 weeks (742.0±158.5) in comparison with the baseline (319.6±40.2) and the sedentary (261.6+42.2) groups. Free fatty acids and glycogen stores (liver, soleus muscle and gastrocnemius muscle) increased after 12 weeks of monotonous training but aerobic and anaerobic performances were unchanged in relation to the sedentary group. The monotonous training at LM increased the level of energy substrates, unchanged aerobic performance, reduced anaerobic capacity and increased the serum CK concentration; however, the rats did not achieve the predicted training volume.

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Aims: Describe the impact of surgery, radiotherapy and chemoradiation in the pelvic floor functions in cervical cancer patients. Materials and Methods: A prospective study with women submitted to radical hysterectomy (RH) (n = 20),exclusive radiotherapy (RT) (n= 20)or chemoradiation (CT/RT)(n = 20)for invasive cervical cancer. Urinary, intestinal and sexual function, as well as vaginal length and pelvic floor musclecontraction were evaluated. Comparisons between groups were performed by Kruskal-Wallis and Chi-square tests (p < 0.05). Results: The groups were similar in stress urinary incontinence incidence (p = 0.56), urinary urgency (p = 0.44),urge incontinence (p = 0.54),nocturia(p = 0.53), incomplete bowel emptying (p = 0.76),bowel urgency(p = 0.12)and soilage(p = 0.43). The CT/ RT group presented a higher urinary frequency(p < 0.001)and diarrhea(p = 0.025). Patients in the RH group were more sexually active(p = 0.01) and experienced less dyspareunia (p = 0.021). Vaginal length was shorter in RT group (5.5 ± 1.9 cm) and CT/ RT(.3 ± 1.5 cm) than in the RH group (7.4 ± 1.1 cm) (p < 0.001). Pelvic floor muscle contraction was similar (p = 0.302). Conclusions: RT and CT/RT treatment for cervical carcinoma are more associated to sexual and intestinal dysfunctions.

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This work analyses a hypothetically improved perturbative approach taking a dressed massive-like gluon propagator and an effective coupling into account. As an early step, corrections were calculated to the ghost and gluon propagators, and the ghost-gluon vertex in the Landau gauge, pure SU(3) Yang-Mills theory. Results were satisfactorily compared with lattice data. © 2013 American Institute of Physics.

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During the eights and nineties many statistical/thermodynamical models were proposed to describe the nucleons' structure functions and distribution of the quarks in the hadrons. Most of these models describe the compound quarks and gluons inside the nucleon as a Fermi / Bose gas respectively, confined in a MIT bag[1] with continuous energy levels. Another models considers discrete spectrum. Some interesting features of the nucleons are obtained by these models, like the sea asymmetries d̄/ū and d̄-ū. © 2013 American Institute of Physics.

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

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Anuran larvae, which are otherwise simple in shape, typically have complex keratinized mouthparts (i.e. labial teeth and jaw sheaths) that allow them to graze upon surfaces. The diversity in these structures among species presumably reflects specializations that allow for maximal feeding efficiency on different types of food. However, we lack a general understanding of how these oral structures function during feeding. We used high-speed digital imaging (500 Hz) to observe tadpoles of six species from the anuran family Hylidae grazing on a standardized food-covered substrate. Tadpoles of these species vary in the number of labial tooth rows, belong to two different feeding guilds (benthic and nektonic), and inhabit ponds and streams. We confirmed that the labial teeth in these species serve two functions: anchoring the mouth to the substrate and raking material off of the substrate. In general, tadpoles with a larger maximum gape or those with fewer labial tooth rows opened and closed their mouths slower than tadpoles with smaller gape or more tooth rows. Nektonic feeding tadpoles released each of their tooth rows proportionally earlier in the gape cycle compared with benthic feeding tadpoles. Lastly, we found some support for the idea that deformation of the jaw sheaths during a feeding cycle is predictable based on tadpole feeding guild. Collectively, our data show that anatomical (e.g. number of labial teeth) and ecological features (e.g. feeding guild) of tadpoles significantly influence how tadpoles open and close their mouths during feeding. © 2013. Published by The Company of Biologists Ltd.