Masticatory muscle activity during maximum voluntary clench in different research diagnostic criteria for temporomandibular disorders (RDC/TMD) groups

The research diagnostic criteria for temporomandibular disorders (RDC/TMD) are used for the classification of patients with temporomandibular disorders (TMD). Surface electromyography of the right and left masseter and temporalis muscles was performed during Maximum teeth clenching in 103 TMD patients subdivided according to the RDC/TMD into 3 non-overlapping groups: (a) 25 myogenous; (b) 61 arthrogenous; and (c) 17 psycogenous patients. Thirty-two control subjects matched for sex and age were also measured. During clenching, standardized total muscle activities (electromyographic potentials over time) significantly differed: 131.7 mu V/mu V s % in the normal subjects, 117.6 mu V/mu V s % in the myogenous patients, 105.3 mu V/mu V s % in the arthrogenous patients, 88.7 mu V/mu V s % in the psycogenous patients (p < 0.001, analysis of covariance). Symmetry in the temporalis muscles was larger in normal subjects (86.3%) and in myogenous patients (84.9%) than in arthrogenous (82.7%), and psycogenous patients (80.5%) (p=0.041). No differences were found for masseter muscle symmetry and torque coefficient (p>0.05). Surface electromyography of the masticatory muscles allowed an objective discrimination among different RDC/TMD subgroups. This evaluation could assist conventional clinical assessments. (C) 2007 Elsevier Ltd. All rights reserved.

Experimentation on Wind Powered Hydraulic Heating System

It is common knowledge of the world’s dependency on fossil fuel for energy, its unsustainability on the long run and the changing trend towards renewable energy as an alternative energy source. This aims to cut down greenhouse gas emission and its impact on the rate of ecological and climatic change. Quite remarkably, wind energy has been one of many focus areas of renewable energy sources and has attracted lots of investment and technological advancement. The objective of this research is to explore wind energy and its application in household heating. This research aims at applying experimental approach in real time to study and verify a virtually simulated wind powered hydraulic house heating system. The hardware components comprise of an integrated hydraulic pump, flow control valve, hydraulic fluid and other hydraulic components. The system design and control applies hardware in-the-loop (HIL) simulation setup. Output signal from the semi-empirical turbine modelling controls the integrated motor to generate flow. Throttling the volume flow creates pressure drop across the valve and subsequently thermal power in the system to be outputted using a heat exchanger. Maximum thermal power is achieved by regulating valve orifice to achieve optimum system parameter. Savonius rotor is preferred for its low inertia, high starting torque and ease of design and maintenance characteristics, but lags in power efficiency. A prototype turbine design is used; with power output in range of practical Savonius turbine. The physical mechanism of the prototype turbine’s augmentation design is not known and will not be a focus in this study.

Isokinetic analysis of the elbow joint in children with cerebral palsy

The joint torque is an important variable related to children with cerebral palsy. The present study analyzed kinetic parameters during elbow flexion and extension movements in healthy and cerebral palsy children. Ten healthy and 10 cerebral palsy children participated of the study. An isokinetic dynamometer was used to measure the elbow mean peak torque, mean angle peak torque, coefficient of variation and acceleration during flexion and extension movements at different angular speeds. The mean peak torque on extension movement in healthy children group was significant higher compared to the cerebral palsy group. The coefficient of variation on both flexion and extension movements was significantly higher in cerebral palsy group. However there were significantly difference on both groups compared the lowest and highest velocities. Although the results showed no difference in flexor peak torque, the acceleration is significantly lower in lowest and highest angular velocity.

Análise isocinética da articulação do cotovelo em crianças com paralisia cerebral

A quantidade de torque aplicado na articulação é uma medida de aptidão física importante para crianças com paralisia cerebral. O presente estudo analisou parâmetros cinéticos na articulação do cotovelo em crianças saudáveis e com paralisia cerebral. Participaram 10 crianças com paralisia cerebral e 10 crianças sem comprometimento neurológico. Avaliou-se a média do pico de torque, média do ângulo do pico de torque, coeficiente de variação do torque e aceleração angular do movimento de flexo-extensão do cotovelo nas velocidades com um dinamômetro isocinético. A média de pico de torque (extensão), aceleração (flexão) e coeficiente de variação (flexão e extensão) são diferentes entre grupos. Conclui-se que o torque e aceleração sofreram interferências no movimento de flexo-extensão; as principais diferenças encontradas foram entre os extremos das velocidades; não houve diferenças no ângulo do pico de torque. A espasticidade não interferiu na força dos músculos agonistas do movimento de flexão da articulação do cotovelo.

Reliability of electromyographic and torque measures during isometric axial rotation exertions of the trunk

Objective: The aim of the present study was to investigate the between-days reliability of electromyographic (EMG) measurement of 6 bilateral trunk muscles and also the torque output in 3 planes during isometric right and left axial rotation at different exertion levels. Methods: Ten healthy subjects performed isometric right and left axial rotation at 100, 70, 50 and 30% maximum voluntary contractions in two testing sessions at least 7 days apart. EMG amplitude and frequency analyses of the recorded surface EMG signals were performed for rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured. Results: For both EMG amplitude and frequency values, good (intraclass correlation coefficient, ICC = 0.75-0.89) to excellent (ICC greater than or equal to 0.90) reliability was found in the 6 trunk muscles at different exertion levels during axial rotation. The reliability of both maximal isometric axial rotation torque and coupling torques in sagittal and coronal planes were found to be excellent (ICC greater than or equal to 0.93). Conclusions: Good to excellent reliability of EMG measures of trunk muscles and torque measurements during isometric axial rotation was demonstrated. This provides further confidence of using EMG and triaxial torque assessment as outcome measures in rehabilitation and in the evaluation of the human performance in the work place. (C) 2003 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Friction torque in grease lubricated thrust ball bearings

Thrust ball bearings lubricated with several different greases were tested on a modified Four-Ball Machine, where the Four-Ball arrangement was replaced by a bearing assembly. The friction torque and operating temperatures in a thrust ball bearing were measured during the tests. At the end of each test a grease sample was analyzed through ferrographic techniques in order to quantify and evaluate bearing wear. A rolling bearing friction torque model was used and the coefficient of friction in full film lubrication was determined for each grease, depending on the operating conditions. The experimental results obtained showed that grease formulation had a very significant influence on friction torque and operating temperature. The friction torque depends on the viscosity of the grease base oil, on its nature (mineral, ester, PAO, etc.), on the coefficient of friction in full film conditions, but also on the interaction between grease thickener and base oil, which affected contact replenishment and contact starvation, and thus influenced the friction torque.

Maximal isokinetic peak torque and EMG activity determined by shorter ranges of motion

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.

Efeito da prática no controle de torque isométrico em crianças com transtorno de desenvolvimento de coordenação

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Análise da influência do torque de montagem na resistência de parafusos de fixação

Whereas the assembly torque calculation has great importance on efficiency and life of bolts, the objective of this study was to analyze the combined stresses during assembly, the friction coefficient, compare the rupture torque results with the indicated torques by standards and to present a new torque method without the stress combination (shear stress and normal stresses). For this study were carried eighteen tests with different diameters and materials, this bolts were undergoing five ranges torque until the breaking torque. With the experimental rupture torque values for each test and with the bolt quality certificate was possible to calculate the friction coefficient so compared with the theory. Another comparison was the experimental rupture torque with assembly torque indicated by NBR-8800 and ASME-PCC. The main conclusion are related to combined stress, because for this factor can fail at the assembly time, so for in some cases must use the tensioning method, because in this method won't be present torsional stresses

Análise da correlação entre índices radiomorfométricos de densidade óssea, perfil de qualidade óssea em software de implante, quociente de estabilidade e torque de inserção em implantes

A qualidade óssea, bem como a estabilidade inicial dos implantes, está diretamente relacionada com o sucesso das reabilitações na implantodontia. O presente estudo teve como objetivo analisar a correlação entre índices radiomorfométricos de densidade óssea por meio de radiografias panorâmicas, perfil de qualidade óssea com o auxílio de Tomografia Computadorizada de Feixe Cônico (TCFC) com o uso do software de imagens OsiriX, Análise da Frequência de Ressonância (RFA) e Torque de Inserção do implante. Foram avaliados 160 implantes de 72 indivíduos, com média etária de 55,5 (±10,5) anos. Nas radiografias panorâmicas foram obtidos os índices IM, IPM e ICM, e nas tomografias computadorizadas de feixe cônico, os valores de pixels e a espessura da cortical da crista óssea alveolar, além da estabilidade primária por meio do torque de inserção e análise da frequência de ressonância. Os resultados foram analisados pelo coeficiente de correlação de Spearman, para p<= 0,01 foi obtido entre o torque de inserção e valores de pixels (0.330), o torque de inserção e a espessura da cortical da crista alveolar (0.339), o torque de inserção e o ISQ vestibulo-lingual (0.193), os valores de pixels e espessura da cortical da crista alveolar (0.377), as duas direções vestíbulo-lingual e mesio-distal do ISQ (0.674), o ISQ vestíbulo-lingual e a espessura da cortical da crista alveolar (0.270); os índices radiomorfométricos foram correlacionados entre eles e para p<= 0,05 foi obtido entre torque de inserção e ISQ mesio-distal (0.131), entre o ISQ vestibulo-lingual e os valores de pixels (0.156) e ISQ mesio-distal e IPMI esquerdo (0.149) e ISQ mesio-distal e IPMS esquerdo (0.145). Existe correlação entre a TCFC, o torque de inserção e a RFA na avaliação da qualidade óssea. É possível utilizar, pré-cirurgicamente, os exames de TCFC para avaliar a qualidade e quantidade óssea, tendo em vista as correlações obtidas neste estudo.

Torque articular e ativação dos musculos biceps femoral e semi-tendineo durante movimentos isocineticos de flexão do joelho em atletas de futebol

Universidade Estadual de Campinas . Faculdade de Educação Física

Efeito das sessões de familiarização sobre o pico de torque e taxa de desenvolvimento de torque : comparações entre jovens, meia idade e idosos = Effect of familiarization sessions on peak torque and rate of torque development : comparisons among young, middle age and elderly

Universidade Estadual de Campinas, Faculdade de Educação Física

Are torque values of preadjusted brackets precise?

OBJECTIVE: The aim of the present study was to verify the torque precision of metallic brackets with MBT prescription using the canine brackets as the representative sample of six commercial brands. MATERIAL AND METHODS: Twenty maxillary and 20 mandibular canine brackets of one of the following commercial brands were selected: 3M Unitek, Abzil, American Orthodontics, TP Orthodontics, Morelli and Ortho Organizers. The torque angle, established by reference points and lines, was measured by an operator using an optical microscope coupled to a computer. The values were compared to those established by the MBT prescription. RESULTS: The results showed that for the maxillary canine brackets, only the Morelli torque (-3.33º) presented statistically significant difference from the proposed values (-7º). For the mandibular canines, American Orthodontics (-6.34º) and Ortho Organizers (-6.25º) presented statistically significant differences from the standards (-6º). Comparing the brands, Morelli presented statistically significant differences in comparison with all the other brands for maxillary canine brackets. For the mandibular canine brackets, there was no statistically significant difference between the brands. CONCLUSIONS: There are significant variations in torque values of some of the brackets assessed, which would clinically compromise the buccolingual positioning of the tooth at the end of orthodontic treatment.

Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference

The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS) of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics) and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs) of the metals and ceramics. Verabond (VB) Ni-Cr-Be alloy, Verabond II (VB2), Ni-Cr alloy, Pors-on 4 (P), Pd-Ag alloy, and IPS (I) and Duceram (D) ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length) made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length) of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01) for the MCBS test results (MPa), with PI showing higher MCBS (67.72) than the other pairs, which did not present any significant differences. The CTE (10-6 oC-1) differences were: VBI (0.54), VBD (1.33), VB2I (-0.14), VB2D (0.63), PI (1.84) and PD (2.62). Pearson's correlation test (r=0.17) was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.

Relation between implant/abutment vertical misfit and torque loss of abutment screws

This study investigated whether there is a direct correlation between the level of vertical misfit at the abutment/implant interface and torque losses (detorque) in abutment screws. A work model was obtained from a metal matrix with five 3.75 x 9 mm external hex implants with standard platform (4.1 mm). Four frameworks were waxed using UCLA type abutments and one-piece cast in commercially pure titanium. The misfit was analyzed with a comparator microscope after 20 Ncm torque. The highest value of misfit observed per abutment was used. The torque required to loose the screw was evaluated using a digital torque meter. The torque loss values, measured by the torque meter, were assumed as percentage of initial torque (100%) given to abutment screws. Pearson's correlation (α=0.05) between the misfit values (29.08 ± 8.78 µm) and the percentage of detorque (50.71 ± 11.37%) showed no statistically significant correlation (p=0.295). Within the limitations of this study, it may be concluded that great vertical misfits dot not necessarily implies in higher detorque values.