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Sample records for active joint torques

  1. Space Suit Joint Torque Testing

    NASA Technical Reports Server (NTRS)

    Valish, Dana J.

    2011-01-01

    In 2009 and early 2010, a test was performed to quantify the torque required to manipulate joints in several existing operational and prototype space suits in an effort to develop joint torque requirements appropriate for a new Constellation Program space suit system. The same test method was levied on the Constellation space suit contractors to verify that their suit design meets the requirements. However, because the original test was set up and conducted by a single test operator there was some question as to whether this method was repeatable enough to be considered a standard verification method for Constellation or other future space suits. In order to validate the method itself, a representative subset of the previous test was repeated, using the same information that would be available to space suit contractors, but set up and conducted by someone not familiar with the previous test. The resultant data was compared using graphical and statistical analysis and a variance in torque values for some of the tested joints was apparent. Potential variables that could have affected the data were identified and re-testing was conducted in an attempt to eliminate these variables. The results of the retest will be used to determine if further testing and modification is necessary before the method can be validated.

  2. Mechanisms of quadriceps muscle weakness in knee joint osteoarthritis: the effects of prolonged vibration on torque and muscle activation in osteoarthritic and healthy control subjects

    PubMed Central

    2011-01-01

    Introduction A consequence of knee joint osteoarthritis (OA) is an inability to fully activate the quadriceps muscles, a problem termed arthrogenic muscle inhibition (AMI). AMI leads to marked quadriceps weakness that impairs physical function and may hasten disease progression. The purpose of the present study was to determine whether γ-loop dysfunction contributes to AMI in people with knee joint OA. Methods Fifteen subjects with knee joint OA and 15 controls with no history of knee joint pathology participated in this study. Quadriceps and hamstrings peak isometric torque (Nm) and electromyography (EMG) amplitude were collected before and after 20 minutes of 50 Hz vibration applied to the infrapatellar tendon. Between-group differences in pre-vibration torque were analysed using a one-way analysis of covariance, with age, gender and body mass (kg) as the covariates. If the γ-loop is intact, vibration should decrease torque and EMG levels in the target muscle; if dysfunctional, then torque and EMG levels should not change following vibration. One-sample t tests were thus undertaken to analyse whether percentage changes in torque and EMG differed from zero after vibration in each group. In addition, analyses of covariance were utilised to analyse between-group differences in the percentage changes in torque and EMG following vibration. Results Pre-vibration quadriceps torque was significantly lower in the OA group compared with the control group (P = 0.005). Following tendon vibration, quadriceps torque (P < 0.001) and EMG amplitude (P ≤0.001) decreased significantly in the control group but did not change in the OA group (all P > 0.299). Hamstrings torque and EMG amplitude were unchanged in both groups (all P > 0.204). The vibration-induced changes in quadriceps torque and EMG were significantly different between the OA and control groups (all P < 0.011). No between-group differences were observed for the change in hamstrings torque or EMG (all P > 0

  3. Static torque-angle relation of human elbow joint estimated with artificial neural network technique.

    PubMed

    Uchiyama, T; Bessho, T; Akazawa, K

    1998-06-01

    Static relations between elbow joint angle and torque at constant muscle activity in normal volunteers were investigated with the aid of an artificial neural network technique. A subject sat on a chair and moved his upper- and forearm in a horizontal plane at the height of his shoulder. The subject was instructed to maintain the elbow joint at a pre-determined angle. The wrist was then pulled to extend the elbow joint by the gravitational force of a weight hanging from a pulley. Integrated electromyograms (IEMGs), elbow and shoulder joint angles and elbow joint torque were measured. Then the relation among IEMGs, joint angles and torque was modeled with the aid of the artificial neural network, where IEMGs and joint angles were the inputs and torque was the output. After back propagation learning, we presented various combinations of IEMGs, shoulder and elbow joint angles to the model and estimated the elbow joint torque to obtain the torque-angle relation for constant muscle activation. The elbow joint torque increased and then decreased with extension of the elbow joint. This suggests that if the forearm is displaced from an equilibrium point, the torque angle relation would not act like a simple spring. In a view of the musculoskeletal structure of the elbow joint, the relation between the elbow joint angle and the moment arm of the elbow flexor muscles seems to have a dominant effect on the torque-angle relation. PMID:9755039

  4. Space Suit Joint Torque Measurement Method Validation

    NASA Technical Reports Server (NTRS)

    Valish, Dana; Eversley, Karina

    2012-01-01

    In 2009 and early 2010, a test method was developed and performed to quantify the torque required to manipulate joints in several existing operational and prototype space suits. This was done in an effort to develop joint torque requirements appropriate for a new Constellation Program space suit system. The same test method was levied on the Constellation space suit contractors to verify that their suit design met the requirements. However, because the original test was set up and conducted by a single test operator there was some question as to whether this method was repeatable enough to be considered a standard verification method for Constellation or other future development programs. In order to validate the method itself, a representative subset of the previous test was repeated, using the same information that would be available to space suit contractors, but set up and conducted by someone not familiar with the previous test. The resultant data was compared using graphical and statistical analysis; the results indicated a significant variance in values reported for a subset of the re-tested joints. Potential variables that could have affected the data were identified and a third round of testing was conducted in an attempt to eliminate and/or quantify the effects of these variables. The results of the third test effort will be used to determine whether or not the proposed joint torque methodology can be applied to future space suit development contracts.

  5. Ankle and hip postural strategies defined by joint torques.

    PubMed

    Runge, C F; Shupert, C L; Horak, F B; Zajac, F E

    1999-10-01

    Previous studies have identified two discrete strategies for the control of posture in the sagittal plane based on EMG activations, body kinematics, and ground reaction forces. The ankle strategy was characterized by body sway resembling a single-segment-inverted pendulum and was elicited on flat support surfaces. In contrast, the hip strategy was characterized by body sway resembling a double-segment inverted pendulum divided at the hip and was elicited on short or compliant support surfaces. However, biomechanical optimization models have suggested that hip strategy should be observed in response to fast translations on a flat surface also, provided the feet are constrained to remain in contact with the floor and the knee is constrained to remain straight. The purpose of this study was to examine the experimental evidence for hip strategy in postural responses to backward translations of a flat support surface and to determine whether analyses of joint torques would provide evidence for two separate postural strategies. Normal subjects standing on a flat support surface were translated backward with a range of velocities from fast (55 cm/s) to slow (5 cm/s). EMG activations and joint kinematics showed pattern changes consistent with previous experimental descriptions of mixed hip and ankle strategy with increasing platform velocity. Joint torque analyses revealed the addition of a hip flexor torque to the ankle plantarflexor torque during fast translations. This finding indicates the addition of hip strategy to ankle strategy to produce a continuum of postural responses. Hip torque without accompanying ankle torque (pure hip strategy) was not observed. Although postural control strategies have previously been defined by how the body moves, we conclude that joint torques, which indicate how body movements are produced, are useful in defining postural control strategies. These results also illustrate how the biomechanics of the body can transform discrete control

  6. Ankle and hip postural strategies defined by joint torques

    NASA Technical Reports Server (NTRS)

    Runge, C. F.; Shupert, C. L.; Horak, F. B.; Zajac, F. E.; Peterson, B. W. (Principal Investigator)

    1999-01-01

    Previous studies have identified two discrete strategies for the control of posture in the sagittal plane based on EMG activations, body kinematics, and ground reaction forces. The ankle strategy was characterized by body sway resembling a single-segment-inverted pendulum and was elicited on flat support surfaces. In contrast, the hip strategy was characterized by body sway resembling a double-segment inverted pendulum divided at the hip and was elicited on short or compliant support surfaces. However, biomechanical optimization models have suggested that hip strategy should be observed in response to fast translations on a flat surface also, provided the feet are constrained to remain in contact with the floor and the knee is constrained to remain straight. The purpose of this study was to examine the experimental evidence for hip strategy in postural responses to backward translations of a flat support surface and to determine whether analyses of joint torques would provide evidence for two separate postural strategies. Normal subjects standing on a flat support surface were translated backward with a range of velocities from fast (55 cm/s) to slow (5 cm/s). EMG activations and joint kinematics showed pattern changes consistent with previous experimental descriptions of mixed hip and ankle strategy with increasing platform velocity. Joint torque analyses revealed the addition of a hip flexor torque to the ankle plantarflexor torque during fast translations. This finding indicates the addition of hip strategy to ankle strategy to produce a continuum of postural responses. Hip torque without accompanying ankle torque (pure hip strategy) was not observed. Although postural control strategies have previously been defined by how the body moves, we conclude that joint torques, which indicate how body movements are produced, are useful in defining postural control strategies. These results also illustrate how the biomechanics of the body can transform discrete control

  7. Results and Analysis from Space Suit Joint Torque Testing

    NASA Technical Reports Server (NTRS)

    Matty, Jennifer E.; Aitchison, Lindsay

    2009-01-01

    A space suit s mobility is critical to an astronaut s ability to perform work efficiently. As mobility increases, the astronaut can perform tasks for longer durations with less fatigue. The term mobility, with respect to space suits, is defined in terms of two key components: joint range of motion and joint torque. Individually these measures describe the path which in which a joint travels and the force required to move it through that path. Previous space suits mobility requirements were defined as the collective result of these two measures and verified by the completion of discrete functional tasks. While a valid way to impose mobility requirements, such a method does necessitate a solid understanding of the operational scenarios in which the final suit will be performing. Because the Constellation space suit system requirements are being finalized with a relatively immature concept of operations, the Space Suit Element team elected to define mobility in terms of its constituent parts to increase the likelihood that the future pressure garment will be mobile enough to enable a broad scope of undefined exploration activities. The range of motion requirements were defined by measuring the ranges of motion test subjects achieved while performing a series of joint maximizing tasks in a variety of flight and prototype space suits. The definition of joint torque requirements has proved more elusive. NASA evaluated several different approaches to the problem before deciding to generate requirements based on unmanned joint torque evaluations of six different space suit configurations being articulated through 16 separate joint movements. This paper discusses the experiment design, data analysis and results, and the process used to determine the final values for the Constellation pressure garment joint torque requirements.

  8. Combined effects of body composition and ageing on joint torque, muscle activation and co-contraction in sedentary women.

    PubMed

    Tomlinson, D J; Erskine, R M; Morse, C I; Winwood, K; Onambélé-Pearson, G L

    2014-06-01

    This study aimed to establish the interplay between body mass, adiposity, ageing and determinants of skeletal muscle strength. One hundred and two untrained healthy women categorised by age into young (Y) (mean ± SD, 26.7 ± 9.4 years) vs. old (O) (65.1 ± 7.2 years) were assessed for body fat, lean mass, plantar flexion and dorsiflexion maximum voluntary isometric contraction (MVC) torque, muscle activation capacity and antagonist muscle co-contraction. MVC torque normalised to body mass in the obese group was 35 and 29 % lower (p < 0.05) in Y and 34 and 31 % lower (p < 0.05) in O, compared with underweight and normal weight individuals, respectively. Y with ≥40 % body fat had significantly lower activation than Y with <40 % body fat (88.3 vs. 94.4 %, p < 0.05), but O did not exhibit this effect. Co-contraction was affected by ageing (16.1 % in O vs. 13.8 % in Y, p < 0.05) but not body composition. There were significant associations between markers of body composition, age, strength and activation capacity, with the strongest correlation between muscle strength and total body mass (r (2) = 0.508 in Y, p < 0.001, vs. r (2) = 0.204 in O, p < 0.01). Furthermore, the age-related loss in plantar flexion (PF) MVC torque was exacerbated in obese compared to underweight, normal weight and overweight individuals (-0.96 vs. -0.54, -0.57 and -0.57 % per year, p < 0.05). The negative impact of adiposity on muscle performance is associated with not only muscular but also neural factors. Overall, the effects of ageing and obesity on this system are somewhat cumulative. PMID:24744050

  9. The effect of knee joint angle on torque control.

    PubMed

    Sosnoff, Jacob J; Voudrie, Stefani J; Ebersole, Kyle T

    2010-01-01

    The purpose of the author's investigation was to examine the effect of knee joint angle on torque control of the quadriceps muscle group. In all, 12 healthy adults produced maximal voluntary contractions and submaximal torque (15, 30, and 45% MVC [maximal voluntary contraction]) at leg flexion angles of 15 degrees , 30 degrees , 60 degrees , and 90 degrees below the horizontal plane. As expected, MVC values changed with respect to joint angle with maximum torque output being greatest at 60 degrees and least at 15 degrees . During the submaximal tasks, participants appropriately scaled their torque output to the required targets. Absolute variability (i.e., standard deviation) of torque output was greatest at 60 degrees and 90 degrees knee flexion. However, relative variability as indexed by coefficient of variation (CV) decreased as joint angle increased, with the greatest CV occurring at 15 degrees . These results are congruent with the hypothesis that joint angle influences the control of torque. PMID:19906637

  10. Results and Analysis from Space Suit Joint Torque Testing

    NASA Technical Reports Server (NTRS)

    Matty, Jennifer

    2010-01-01

    This joint mobility KC lecture included information from two papers, "A Method for and Issues Associated with the Determination of Space Suit Joint Requirements" and "Results and Analysis from Space Suit Joint Torque Testing," as presented for the International Conference on Environmental Systems in 2009 and 2010, respectively. The first paper discusses historical joint torque testing methodologies and approaches that were tested in 2008 and 2009. The second paper discusses the testing that was completed in 2009 and 2010.

  11. Dimensionality of joint torques and muscle patterns for reaching.

    PubMed

    Russo, Marta; D'Andola, Mattia; Portone, Alessandro; Lacquaniti, Francesco; d'Avella, Andrea

    2014-01-01

    Muscle activities underlying many motor behaviors can be generated by a small number of basic activation patterns with specific features shared across movement conditions. Such low-dimensionality suggests that the central nervous system (CNS) relies on a modular organization to simplify control. However, the relationship between the dimensionality of muscle patterns and that of joint torques is not fixed, because of redundancy and non-linearity in mapping the former into the latter, and needs to be investigated. We compared the torques acting at four arm joints during fast reaching movements in different directions in the frontal and sagittal planes and the underlying muscle patterns. The dimensionality of the non-gravitational components of torques and muscle patterns in the spatial, temporal, and spatiotemporal domains was estimated by multidimensional decomposition techniques. The spatial organization of torques was captured by two or three generators, indicating that not all the available coordination patterns are employed by the CNS. A single temporal generator with a biphasic profile was identified, generalizing previous observations on a single plane. The number of spatiotemporal generators was equal to the product of the spatial and temporal dimensionalities and their organization was essentially synchronous. Muscle pattern dimensionalities were higher than torques dimensionalities but also higher than the minimum imposed by the inherent non-negativity of muscle activations. The spatiotemporal dimensionality of the muscle patterns was lower than the product of their spatial and temporal dimensionality, indicating the existence of specific asynchronous coordination patterns. Thus, the larger dimensionalities of the muscle patterns may be required for CNS to overcome the non-linearities of the musculoskeletal system and to flexibly generate endpoint trajectories with simple kinematic features using a limited number of building blocks. PMID:24624078

  12. Dimensionality of joint torques and muscle patterns for reaching

    PubMed Central

    Russo, Marta; D'Andola, Mattia; Portone, Alessandro; Lacquaniti, Francesco; d'Avella, Andrea

    2014-01-01

    Muscle activities underlying many motor behaviors can be generated by a small number of basic activation patterns with specific features shared across movement conditions. Such low-dimensionality suggests that the central nervous system (CNS) relies on a modular organization to simplify control. However, the relationship between the dimensionality of muscle patterns and that of joint torques is not fixed, because of redundancy and non-linearity in mapping the former into the latter, and needs to be investigated. We compared the torques acting at four arm joints during fast reaching movements in different directions in the frontal and sagittal planes and the underlying muscle patterns. The dimensionality of the non-gravitational components of torques and muscle patterns in the spatial, temporal, and spatiotemporal domains was estimated by multidimensional decomposition techniques. The spatial organization of torques was captured by two or three generators, indicating that not all the available coordination patterns are employed by the CNS. A single temporal generator with a biphasic profile was identified, generalizing previous observations on a single plane. The number of spatiotemporal generators was equal to the product of the spatial and temporal dimensionalities and their organization was essentially synchronous. Muscle pattern dimensionalities were higher than torques dimensionalities but also higher than the minimum imposed by the inherent non-negativity of muscle activations. The spatiotemporal dimensionality of the muscle patterns was lower than the product of their spatial and temporal dimensionality, indicating the existence of specific asynchronous coordination patterns. Thus, the larger dimensionalities of the muscle patterns may be required for CNS to overcome the non-linearities of the musculoskeletal system and to flexibly generate endpoint trajectories with simple kinematic features using a limited number of building blocks. PMID:24624078

  13. Virtual Passive Controller for Robot Systems Using Joint Torque Sensors

    NASA Technical Reports Server (NTRS)

    Aldridge, Hal A.; Juang, Jer-Nan

    1997-01-01

    This paper presents a control method based on virtual passive dynamic control that will stabilize a robot manipulator using joint torque sensors and a simple joint model. The method does not require joint position or velocity feedback for stabilization. The proposed control method is stable in the sense of Lyaponov. The control method was implemented on several joints of a laboratory robot. The controller showed good stability robustness to system parameter error and to the exclusion of nonlinear dynamic effects on the joints. The controller enhanced position tracking performance and, in the absence of position control, dissipated joint energy.

  14. Results and Analysis from Space Suit Joint Torque Testing

    NASA Technical Reports Server (NTRS)

    Matty, Jennifer

    2010-01-01

    A space suit's mobility is critical to an astronaut's ability to perform work efficiently. As mobility increases, the astronaut can perform tasks for longer durations with less fatigue. Mobility can be broken down into two parts: range of motion (ROM) and torque. These two measurements describe how the suit moves and how much force it takes to move. Two methods were chosen to define mobility requirements for the Constellation Space Suit Element (CSSE). One method focuses on range of motion and the second method centers on joint torque. A joint torque test was conducted to determine a baseline for current advanced space suit joint torques. This test utilized the following space suits: Extravehicular Mobility Unit (EMU), Advanced Crew Escape Suit (ACES), I-Suit, D-Suit, Enhanced Mobility (EM)- ACES, and Mark III (MK-III). Data was collected data from 16 different joint movements of each suit. The results were then reviewed and CSSE joint torque requirement values were selected. The focus of this paper is to discuss trends observed during data analysis.

  15. Modelling the maximum voluntary joint torque/angular velocity relationship in human movement.

    PubMed

    Yeadon, Maurice R; King, Mark A; Wilson, Cassie

    2006-01-01

    The force exerted by a muscle is a function of the activation level and the maximum (tetanic) muscle force. In "maximum" voluntary knee extensions muscle activation is lower for eccentric muscle velocities than for concentric velocities. The aim of this study was to model this "differential activation" in order to calculate the maximum voluntary knee extensor torque as a function of knee angular velocity. Torque data were collected on two subjects during maximal eccentric-concentric knee extensions using an isovelocity dynamometer with crank angular velocities ranging from 50 to 450 degrees s(-1). The theoretical tetanic torque/angular velocity relationship was modelled using a four parameter function comprising two rectangular hyperbolas while the activation/angular velocity relationship was modelled using a three parameter function that rose from submaximal activation for eccentric velocities to full activation for high concentric velocities. The product of these two functions gave a seven parameter function which was fitted to the joint torque/angular velocity data, giving unbiased root mean square differences of 1.9% and 3.3% of the maximum torques achieved. Differential activation accounts for the non-hyperbolic behaviour of the torque/angular velocity data for low concentric velocities. The maximum voluntary knee extensor torque that can be exerted may be modelled accurately as the product of functions defining the maximum torque and the maximum voluntary activation level. Failure to include differential activation considerations when modelling maximal movements will lead to errors in the estimation of joint torque in the eccentric phase and low velocity concentric phase. PMID:16389087

  16. Active Vibration Control of a Large Flexible Manipulator by Inertial Force and Joint Torque. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Lee, Soo Han

    1988-01-01

    The efficiency and positional accuracy of a lightweight flexible manipulator are limited by its flexural vibrations, which last after a gross motion is completed. The vibration delays subsequent operations. In the proposed work, the vibration is suppressed by inertial force of a small arm in addition to the joint actuators and passive damping treatment. The proposed approach is: (1) Dynamic modeling of a combined system, a large flexible manipulator and a small arm, (2) Determination of optimal sensor location and controller algorithm, and (3) Verification of the fitness of model and the performance of controller.

  17. Design of a telerobotic controller with joint torque sensors

    NASA Technical Reports Server (NTRS)

    Jansen, J. F.; Herndon, J. N.

    1990-01-01

    The purpose was to analytically show how to design a joint controller for a telerobotic system when joint torque sensors are available. Other sensors such as actuator position, actuator velocity, joint position, and joint velocity are assumed to be accessible; however, the results will also be useful when only partial measurements are available. The controller presented can be applied to either mode of operation of a manipulator (i.e., teleoperation or robotic). Mechanical manipulators with high levels of friction are assumed. The results are applied to a telerobotic system built for NASA. Very high levels of friction have been reduced using high-gain feedback while avoiding limit cycles.

  18. A robotic apparatus that dictates torque fields around joints without affecting inherent joint dynamics.

    PubMed

    Oytam, Yalchin; Lloyd, David; Reid, Campbell S; de Rugy, Aymar; Carson, Richard G

    2010-10-01

    This manuscript describes how motor behaviour researchers who are not at the same time expert roboticists may implement an experimental apparatus, which has the ability to dictate torque fields around a single joint on one limb or single joints on multiple limbs without otherwise interfering with the inherent dynamics of those joints. Such an apparatus expands the exploratory potential of the researcher wherever experimental distinction of factors may necessitate independent control of torque fields around multiple limbs, or the shaping of torque fields of a given joint independently of its plane of motion, or its directional phase within that plane. The apparatus utilizes torque motors. The challenge with torque motors is that they impose added inertia on limbs and thus attenuate joint dynamics. We eliminated this attenuation by establishing an accurate mathematical model of the robotic device using the Box-Jenkins method, and cancelling out its dynamics by employing the inverse of the model as a compensating controller. A direct measure of the remnant inertial torque as experienced by the hand during a 50 s period of wrist oscillations that increased gradually in frequency from 1.0 to 3.8 Hz confirmed that the removal of the inertial effect of the motor was effectively complete. PMID:20728232

  19. Design of a telerobotic controller with joint torque sensors

    SciTech Connect

    Jansen, J.F.; Herndon, J.N.

    1990-01-01

    The purpose of this paper is to analytically show how to design a joint controller for a telerobotic system when joint torque sensors are available. Other sensors such as actuator position, actuator velocity, joint position, and joint velocity are assumed to be accessible; however, the results of this paper will also be useful when only partial measurements are available. The controller presented in this paper can be applied to either mode of operation of a manipulator (i.e., teleoperation or robotic). Mechanical manipulators with high levels of friction are assumed in this study. Finally, the results are applied to a telerobotic system built for NASA. Very high levels of friction have been reduced using high-grain feedback while avoiding limit cycles. 14 refs., 5 figs.

  20. Joint forces and torques when walking in shallow water.

    PubMed

    Orselli, Maria Isabel Veras; Duarte, Marcos

    2011-04-01

    This study reports for the first time an estimation of the internal net joint forces and torques on adults' lower limbs and pelvis when walking in shallow water, taking into account the drag forces generated by the movement of their bodies in the water and the equivalent data when they walk on land. A force plate and a video camera were used to perform a two-dimensional gait analysis at the sagittal plane of 10 healthy young adults walking at comfortable speeds on land and in water at a chest-high level. We estimated the drag force on each body segment and the joint forces and torques at the ankle, knee, and hip of the right side of their bodies using inverse dynamics. The observed subjects' apparent weight in water was about 35% of their weight on land and they were about 2.7 times slower when walking in water. When the subjects walked in water compared with walking on land, there were no differences in the angular displacements but there was a significant reduction in the joint torques which was related to the water's depth. The greatest reduction was observed for the ankle and then the knee and no reduction was observed for the hip. All joint powers were significantly reduced in water. The compressive and shear joint forces were on average about three times lower during walking in water than on land. These quantitative results substantiate the use of water as a safe environment for practicing low-impact exercises, particularly walking. PMID:21334630

  1. Influence of Joint Angle on EMG-Torque Model During Constant-Posture, Torque-Varying Contractions.

    PubMed

    Liu, Pu; Liu, Lukai; Clancy, Edward A

    2015-11-01

    Relating the electromyogram (EMG) to joint torque is useful in various application areas, including prosthesis control, ergonomics and clinical biomechanics. Limited study has related EMG to torque across varied joint angles, particularly when subjects performed force-varying contractions or when optimized modeling methods were utilized. We related the biceps-triceps surface EMG of 22 subjects to elbow torque at six joint angles (spanning 60° to 135°) during constant-posture, torque-varying contractions. Three nonlinear EMG σ -torque models, advanced EMG amplitude (EMG σ ) estimation processors (i.e., whitened, multiple-channel) and the duration of data used to train models were investigated. When EMG-torque models were formed separately for each of the six distinct joint angles, a minimum "gold standard" error of 4.01±1.2% MVC(F90) resulted (i.e., error relative to maximum voluntary contraction at 90° flexion). This model structure, however, did not directly facilitate interpolation across angles. The best model which did so achieved a statistically equivalent error of 4.06±1.2% MVC(F90). Results demonstrated that advanced EMG σ processors lead to improved joint torque estimation as do longer model training durations. PMID:25706722

  2. Maximum voluntary joint torque as a function of joint angle and angular velocity: model development and application to the lower limb.

    PubMed

    Anderson, Dennis E; Madigan, Michael L; Nussbaum, Maury A

    2007-01-01

    Measurements of human strength can be important during analyses of physical activities. Such measurements have often taken the form of the maximum voluntary torque at a single joint angle and angular velocity. However, the available strength varies substantially with joint position and velocity. When examining dynamic activities, strength measurements should account for these variations. A model is presented of maximum voluntary joint torque as a function of joint angle and angular velocity. The model is based on well-known physiological relationships between muscle force and length and between muscle force and velocity and was tested by fitting it to maximum voluntary joint torque data from six different exertions in the lower limb. Isometric, concentric and eccentric maximum voluntary contractions were collected during hip extension, hip flexion, knee extension, knee flexion, ankle plantar flexion and dorsiflexion. Model parameters are reported for each of these exertion directions by gender and age group. This model provides an efficient method by which strength variations with joint angle and angular velocity may be incorporated into comparisons between joint torques calculated by inverse dynamics and the maximum available joint torques. PMID:17485097

  3. Control of torque direction by spinal pathways at the cat ankle joint.

    PubMed

    Nichols, T R; Lawrence, J H; Bonasera, S J

    1993-01-01

    To study the biomechanics of the calcaneal tendon's complex insertion onto the calcaneus, we measured torque-time trajectories exerted by the triceps surae and tibialis anterior muscles in eight unanesthetized decerebrate cats using a multi-axis force-moment sensor placed at the ankle joint. The ankle was constrained to an angle of 110 degrees plantarflexion. Muscles were activated using crossed-extension (XER), flexion (FWR), and caudal cutaneous sural nerve (SNR) reflexes. Torque contributions of other muscles activated by these reflexes were eliminated by denervation or tenotomy. In two animals, miniature pressure transducers were implanted among tendon fibers from the lateral gastrocnemius (LG) muscle that insert straight into the calcaneus or among tendon fibers from the medial gastrocnemius (MG) that cross over and insert on the lateral aspect of calcaneus. Reflexively evoked torques had the following directions: FWR, dorsiflexion and adduction; SNR, plantarflexion and abduction; and XER, plantarflexion and modest abduction or adduction. The proportion of abduction torque to plantarflexion torque was always greater for SNR than XER; this difference was about 50% of the magnitude of abduction torque generated by tetanic stimulation of the peronei. During SNR, pressures were higher in regions of the calcaneal tendon originating from MG than regions originating from LG. Similarly, pressures within the MG portion of the calcaneal tendon were higher during SNR than during XER, although these two reflexes produced matched ankle plantarflexion forces. Selective tenotomies and electromyographic recordings further demonstrated that MG generated most of the torque in response to SNR, while soleus, LG, and MG all generated torques in response to XER.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8150057

  4. Torque linearizing hardware for the electric joint motors of a direct-drive robot

    SciTech Connect

    Muir, P.F.; Bryan, J.R.

    1991-01-01

    Many emerging high-performance robot control algorithms require the command of the joint torques; yet no known commercial robots provide such a capability. In this paper, we describe the design, development, testing and application of a VMEbus-based torque linearizing joint interface board (JIB). One JIB resides between the robot control processor and each joint motor amplifier. The JIB provides the control processor with the capability to read the motor position and apply accurate motor torques. The torque command capability derives from the application of a 128k {times} 8 EPROM lookup table for each motor phase. Because joint motor torque is dependent upon the torque command and the motor position, the hardware is designed to utilize the torque command and the current motor position as the address to retrieve the proper pulse-width for the PWM motor amplifier. The table look-up cycle operates independently of the robot controller at a 40KHz rate to provide constant joint torque as the motor rotates. We identify the proper table entries by an automated in situ data collection procedure. Static torque generation results show that the torque deviations are reduced from as much as 76% to below 5% for each of the three direct-drive motors (two are variable reluctance motors and one is brushless DC) on an AdeptTwo robot. These torque deviations are reduced below 2.5% if only the upper 90% of the torque range is considered. The torque deviations of the non-direct-drive joint are reduced by 50%. Dynamic robot edge following experiments show that the robot speed of operation can be more than doubled for a given applied force accuracy by utilizing the joint torque linearizing boards. 8 refs.

  5. Torque linearizing hardware for the electric joint motors of a direct-drive robot

    SciTech Connect

    Muir, P.F.; Bryan, J.R.

    1991-12-31

    Many emerging high-performance robot control algorithms require the command of the joint torques; yet no known commercial robots provide such a capability. In this paper, we describe the design, development, testing and application of a VMEbus-based torque linearizing joint interface board (JIB). One JIB resides between the robot control processor and each joint motor amplifier. The JIB provides the control processor with the capability to read the motor position and apply accurate motor torques. The torque command capability derives from the application of a 128k {times} 8 EPROM lookup table for each motor phase. Because joint motor torque is dependent upon the torque command and the motor position, the hardware is designed to utilize the torque command and the current motor position as the address to retrieve the proper pulse-width for the PWM motor amplifier. The table look-up cycle operates independently of the robot controller at a 40KHz rate to provide constant joint torque as the motor rotates. We identify the proper table entries by an automated in situ data collection procedure. Static torque generation results show that the torque deviations are reduced from as much as 76% to below 5% for each of the three direct-drive motors (two are variable reluctance motors and one is brushless DC) on an AdeptTwo robot. These torque deviations are reduced below 2.5% if only the upper 90% of the torque range is considered. The torque deviations of the non-direct-drive joint are reduced by 50%. Dynamic robot edge following experiments show that the robot speed of operation can be more than doubled for a given applied force accuracy by utilizing the joint torque linearizing boards. 8 refs.

  6. Torque linearizing hardware for the electric joint motors of a direct-drive robot

    NASA Astrophysics Data System (ADS)

    Muir, P. F.; Bryan, J. R.

    Many emerging high-performance robot control algorithms require the command of the joint torques, yet no known commercial robots provide such a capability. We describe the design, development, testing, and application of a VMEbus-based torque linearizing joint interface board (JIB). One JIB resides between the robot control processor and each joint motor amplifier. The JIB provides the control processor with the capability to read the motor position and apply accurate motor torques. The torque command capability derives from the application of a 128k x 8 EPROM lookup table for each motor phase. Because joint motor torque is dependent upon the torque command and the motor position, the hardware is designed to utilize the torque command and the current motor position as the address to retrieve the proper pulse-width for the PWM motor amplifier. The table look-up cycle operates independently of the robot controller at a 40KHz rate to provide constant joint torque as the motor rotates. We identify the proper table entries by an automated in situ data collection procedure. Static torque generation results show that the torque deviations are reduced from as much as 76 percent to below 5 percent for each of the three direct-drive motors (two are variable reluctance motors and one is brushless DC) on an AdeptTwo robot. These torque deviations are reduced below 2.5 percent if only the upper 90 percent of the torque range is considered. The torque deviations of the non-direct-drive joint are reduced by 50 percent. Dynamic robot edge following experiments show that the robot speed of operation can be more than doubled for a given applied force accuracy by utilizing the joint torque linearizing boards.

  7. Isokinetic Identification of Knee Joint Torques before and after Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Czaplicki, Adam; Jarocka, Marta; Walawski, Jacek

    2015-01-01

    The aim of this study was to evaluate the serial change of isokinetic muscle strength of the knees before and after anterior cruciate ligament reconstruction (ACLR) in physically active males and to estimate the time of return to full physical fitness. Extension and flexion torques were measured for the injured and healthy limbs at two angular velocities approximately 1.5 months before the surgery and 3, 6, and 12 months after ACLR. Significant differences (p ≤ 0.05) in peak knee extension and flexion torques, hamstring/quadriceps (H/Q) strength ratios, uninvolved/involved limb peak torque ratios, and the normalized work of these muscles between the four stages of rehabilitation were identified. Significant differences between extension peak torques for the injured and healthy limbs were also detected at all stages. The obtained results showed that 12 months of rehabilitation were insufficient for the involved knee joint to recover its strength to the level of strength of the uninvolved knee joint. The results helped to evaluate the progress of the rehabilitation and to implement necessary modifications optimizing the rehabilitation training program. The results of the study may also be used as referential data for physically active males of similar age. PMID:26646385

  8. Isokinetic Identification of Knee Joint Torques before and after Anterior Cruciate Ligament Reconstruction.

    PubMed

    Czaplicki, Adam; Jarocka, Marta; Walawski, Jacek

    2015-01-01

    The aim of this study was to evaluate the serial change of isokinetic muscle strength of the knees before and after anterior cruciate ligament reconstruction (ACLR) in physically active males and to estimate the time of return to full physical fitness. Extension and flexion torques were measured for the injured and healthy limbs at two angular velocities approximately 1.5 months before the surgery and 3, 6, and 12 months after ACLR. Significant differences (p ≤ 0.05) in peak knee extension and flexion torques, hamstring/quadriceps (H/Q) strength ratios, uninvolved/involved limb peak torque ratios, and the normalized work of these muscles between the four stages of rehabilitation were identified. Significant differences between extension peak torques for the injured and healthy limbs were also detected at all stages. The obtained results showed that 12 months of rehabilitation were insufficient for the involved knee joint to recover its strength to the level of strength of the uninvolved knee joint. The results helped to evaluate the progress of the rehabilitation and to implement necessary modifications optimizing the rehabilitation training program. The results of the study may also be used as referential data for physically active males of similar age. PMID:26646385

  9. Joint torques in a freely walking insect reveal distinct functions of leg joints in propulsion and posture control.

    PubMed

    Dallmann, Chris J; Dürr, Volker; Schmitz, Josef

    2016-01-27

    Determining the mechanical output of limb joints is critical for understanding the control of complex motor behaviours such as walking. In the case of insect walking, the neural infrastructure for single-joint control is well described. However, a detailed description of the motor output in form of time-varying joint torques is lacking. Here, we determine joint torques in the stick insect to identify leg joint function in the control of body height and propulsion. Torques were determined by measuring whole-body kinematics and ground reaction forces in freely walking animals. We demonstrate that despite strong differences in morphology and posture, stick insects show a functional division of joints similar to other insect model systems. Propulsion was generated by strong depression torques about the coxa-trochanter joint, not by retraction or flexion/extension torques. Torques about the respective thorax-coxa and femur-tibia joints were often directed opposite to fore-aft forces and joint movements. This suggests a posture-dependent mechanism that counteracts collapse of the leg under body load and directs the resultant force vector such that strong depression torques can control both body height and propulsion. Our findings parallel propulsive mechanisms described in other walking, jumping and flying insects, and challenge current control models of insect walking. PMID:26791608

  10. Improving anterior deltoid activity in a musculoskeletal shoulder model - an analysis of the torque-feasible space at the sternoclavicular joint.

    PubMed

    Ingram, David; Engelhardt, Christoph; Farron, Alain; Terrier, Alexandre; Müllhaupt, Philippe

    2016-01-01

    Modelling the shoulder's musculature is challenging given its mechanical and geometric complexity. The use of the ideal fibre model to represent a muscle's line of action cannot always faithfully represent the mechanical effect of each muscle, leading to considerable differences between model-estimated and in vivo measured muscle activity. While the musculo-tendon force coordination problem has been extensively analysed in terms of the cost function, only few works have investigated the existence and sensitivity of solutions to fibre topology. The goal of this paper is to present an analysis of the solution set using the concepts of torque-feasible space (TFS) and wrench-feasible space (WFS) from cable-driven robotics. A shoulder model is presented and a simple musculo-tendon force coordination problem is defined. The ideal fibre model for representing muscles is reviewed and the TFS and WFS are defined, leading to the necessary and sufficient conditions for the existence of a solution. The shoulder model's TFS is analysed to explain the lack of anterior deltoid (DLTa) activity. Based on the analysis, a modification of the model's muscle fibre geometry is proposed. The performance with and without the modification is assessed by solving the musculo-tendon force coordination problem for quasi-static abduction in the scapular plane. After the proposed modification, the DLTa reaches 20% of activation. PMID:26158646

  11. Diffusion of torqued active Brownian particles

    NASA Astrophysics Data System (ADS)

    Sevilla, Francisco J.

    An analytical approach is used to study the diffusion of active Brownian particles that move at constant speed in three-dimensional space, under the influence of passive (external) and active (internal) torques. The Smoluchowski equation for the position distribution of the particles is obtained from the Kramer-Fokker-Planck equation corresponding to Langevin equations for active Brownian particles subject to torques. In addition of giving explicit formulas for the mean square-displacement, the non-Gaussian behavior is analyzed through the kurtosis of the position distribution that exhibits an oscillatory behavior in the short-time limit. FJS acknowledges support from PAPIIT-UNAM through the grant IN113114

  12. Design of a torque-controlled manipulator to analyse the admittance of the wrist joint.

    PubMed

    Schouten, Alfred C; de Vlugt, Erwin; van Hilten, J J Bob; van der Helm, Frans C T

    2006-06-30

    This paper describes the design of a torque-controlled manipulator to identify the dynamics of the wrist joint. With torque disturbances, the subject can actively control the joint angle, giving a natural task. The application of a hybrid haptic controller guarantees linearity over a large bandwidth and adjustable virtual dynamics. The haptic controller has a bandwidth of 50 Hz, meaning that the virtual dynamics are realistically felt at up to 50 Hz. To let the subject 'feel' the torque, disturbances as well as possible the apparent, or virtual, dynamics of the device must be small. The minimal apparent inertia of the device is 1.6 g m(2), which is of the same order as for a normal wrist, and the minimal damping and stiffness are negligible. To judge the accuracy of the manipulator, loads of known physical properties were attached and their parameters were quantified. The parameters of the loads were estimated with a maximum error of 5%. As the eigenfrequency of a (co)-contracted human wrist is approximately 15 Hz, the 50-Hz bandwidth of the haptic device is sufficient to measure all relevant dynamics of the human wrist. With this device, the dynamics of the human wrist joint can be measured under varying virtual dynamics, as well as the effect of neurological dysfunction on human motor control, for example. PMID:16434105

  13. Integrated High-Speed Torque Control System for a Robotic Joint

    NASA Technical Reports Server (NTRS)

    Davis, Donald R. (Inventor); Radford, Nicolaus A. (Inventor); Permenter, Frank Noble (Inventor); Valvo, Michael C. (Inventor); Askew, R. Scott (Inventor)

    2013-01-01

    A control system for achieving high-speed torque for a joint of a robot includes a printed circuit board assembly (PCBA) having a collocated joint processor and high-speed communication bus. The PCBA may also include a power inverter module (PIM) and local sensor conditioning electronics (SCE) for processing sensor data from one or more motor position sensors. Torque control of a motor of the joint is provided via the PCBA as a high-speed torque loop. Each joint processor may be embedded within or collocated with the robotic joint being controlled. Collocation of the joint processor, PIM, and high-speed bus may increase noise immunity of the control system, and the localized processing of sensor data from the joint motor at the joint level may minimize bus cabling to and from each control node. The joint processor may include a field programmable gate array (FPGA).

  14. Active motion assisted by correlated stochastic torques.

    PubMed

    Weber, Christian; Radtke, Paul K; Schimansky-Geier, Lutz; Hänggi, Peter

    2011-07-01

    The stochastic dynamics of an active particle undergoing a constant speed and additionally driven by an overall fluctuating torque is investigated. The random torque forces are expressed by a stochastic differential equation for the angular dynamics of the particle determining the orientation of motion. In addition to a constant torque, the particle is supplemented by random torques, which are modeled as an Ornstein-Uhlenbeck process with given correlation time τ(c). These nonvanishing correlations cause a persistence of the particles' trajectories and a change of the effective spatial diffusion coefficient. We discuss the mean square displacement as a function of the correlation time and the noise intensity and detect a nonmonotonic dependence of the effective diffusion coefficient with respect to both correlation time and noise strength. A maximal diffusion behavior is obtained if the correlated angular noise straightens the curved trajectories, interrupted by small pirouettes, whereby the correlated noise amplifies a straightening of the curved trajectories caused by the constant torque. PMID:21867138

  15. Converting a commercial electric direct-drive robot to operate from joint torque commands

    SciTech Connect

    Muir, P.F.

    1991-07-01

    Many robot control algorithms for high performance in-contact operations including hybrid force/position, stiffness control and impedance control approaches require the command the joint torques. However, most commercially available robots do not provide joint torque command capabilities. The joint command at the user level is typically position or velocity and at the control developer level is voltage, current, or pulse-width, and the torque generated is a nonlinear function of the command and joint position. To enable the application of high performance in-contact control algorithms to commercially available robots, and thereby facilitate technology transfer from the robot control research community to commercial applications, an methodology has been developed to linearize the torque characteristics of electric motor-amplifier combinations. A four degree of freedom Adept 2 robot, having pulse-width modulation amplifiers and both variable reluctance and brushless DC motors, is converted to operate from joint torque commands to demonstrate the methodology. The commercial robot controller is replaced by a VME-based system incorporating special purpose hardware and firmware programmed from experimental data. The performance improvement is experimentally measured and graphically displayed using three-dimensional plots of torque vs command vs position. The average percentage torque deviation over the command and position ranges is reduced from as much as 76% to below 5% for the direct-drive joints 1, 2 and 4 and is cut by one half in the remaining ball-screw driven joint 3. Further, the torque deviation of the direct-drive joints drops below 2.5% if only the upper 90% of the torque range is considered. 23 refs., 20 figs., 2 tabs.

  16. Muscle activity-torque-velocity relations in human elbow extensor muscles.

    PubMed

    Uchiyama, T; Akazawa, K

    1999-01-01

    With the aid of an artificial neural network technique, we investigated relationships between the torque and extending velocity of an elbow at constant muscle activation in healthy volunteers. Each subject sat on a chair and was able to move his upper- and forearm on a shoulder-high horizontal plane. First, with the gravitational force of a weight hanging from a pulley, the subject's wrist was pulled to flex the elbow. Next, the subject was instructed to extend his elbow joint at a constant velocity. Integrated electromyograms (IEMGs), elbow joint angle and torque were measured while the elbow was being extending. Then the relationships among these three variables were modeled using an artificial neural network where IEMGs, joint angle and velocity were the inputs, and torque was the output. After back propagation learning, we presented various combinations of IEMGs, elbow joint angle and velocity to the model, and estimated the elbow joint torque to obtain the torque-velocity relationship for constant muscle activation. The torque decreased in a nearly linear manner as the velocity increased. This was caused by slow extending velocity and was explained by Hill's equation at slow velocity. PMID:10718668

  17. How well do the muscular synergies extracted via non-negative matrix factorisation explain the variation of torque at shoulder joint?

    PubMed

    Moghadam, M Nassajian; Aminian, K; Asghari, M; Parnianpour, M

    2013-01-01

    The way central nervous system manages the excess degrees of freedom to solve kinetic redundancy of musculoskeletal system remains an open question. In this study, we utilise the concept of synergy formation as a simplifying control strategy to find the muscle recruitment based on summation of identified muscle synergies to balance the biomechanical demands (biaxial external torque) during an isometric shoulder task. A numerical optimisation-based shoulder model was used to obtain muscle activation levels when a biaxial external isometric torque is imposed at the shoulder glenohumeral joint. In the numerical simulations, 12 different shoulder torque vectors in the transverse plane are considered. For each selected direction for the torque vector, the resulting muscle activation data are calculated. The predicted muscle activation data are used for grouping muscles in some fixed element synergies by the non-negative matrix factorisation method. Next, torque produced by these synergies are computed and projected in the 2D torque space to investigate the magnitude and direction of torques that each muscle synergy generated. The results confirmed our expectation that few dominant synergies are sufficient to reconstruct the torque vectors and each muscle contributed to more than one synergy. Decomposition of the concatenated data, combining the activation and external torque, provided functional muscle synergies that produced torques in the four principal directions. Four muscle synergies were able to account for more than 95% of variation of the original data. PMID:21970618

  18. The relationship between electrical stimulus and joint torque: a dynamic model.

    PubMed

    Ferrarin, M; Pedotti, A

    2000-09-01

    The knowledge of the behavior of electrically activated muscles is an important requisite for the development of functional electrical stimulation (FES) systems to restore mobility to persons with paralysis. The aim of this work was to develop a model capable of relating electrical parameters to dynamic joint torque for FES applications. The knee extensor muscles, stimulated using surface electrodes, were used for the experimental preparation. Both healthy subjects and people with paraplegia were tested. The dynamics of the lower limb were represented by a nonlinear second order model, which took account of the gravitational and inertial characteristics of the anatomical segments as well as the damping and stiffness properties of the knee joint. The viscous-elastic parameters of the system were identified experimentally through free pendular movements of the leg. Leg movements induced by quadriceps stimulation were acquired too, using a motion analysis system. Results showed that, for the considered experimental conditions, a simple one-pole transfer function is able to model the relationship between stimulus pulsewidth (PW) and active muscle torque. The time constant of the pole was found to depend on the stimulus pattern (ramp or step) while gain was directly dependent on stimulation frequency. PMID:11001514

  19. Experimental Robot Position Sensor Fault Tolerance Using Accelerometers and Joint Torque Sensors

    NASA Technical Reports Server (NTRS)

    Aldridge, Hal A.; Juang, Jer-Nan

    1997-01-01

    Robot systems in critical applications, such as those in space and nuclear environments, must be able to operate during component failure to complete important tasks. One failure mode that has received little attention is the failure of joint position sensors. Current fault tolerant designs require the addition of directly redundant position sensors which can affect joint design. The proposed method uses joint torque sensors found in most existing advanced robot designs along with easily locatable, lightweight accelerometers to provide a joint position sensor fault recovery mode. This mode uses the torque sensors along with a virtual passive control law for stability and accelerometers for joint position information. Two methods for conversion from Cartesian acceleration to joint position based on robot kinematics, not integration, are presented. The fault tolerant control method was tested on several joints of a laboratory robot. The controllers performed well with noisy, biased data and a model with uncertain parameters.

  20. Oscillation of the human ankle joint in response to applied sinusoidal torque on the foot

    PubMed Central

    Agarwal, Gyan C.; Gottlieb, Gerald L.

    1977-01-01

    1. Low-frequency (3-30 Hz) oscillatory rotation of the ankle joint in plantarflexion—dorsiflexion was generated with a torque motor. Torque, rotation about the ankle and electromyograms (e.m.g.s) for the gastrocnemius—soleus and the anterior tibial muscles were recorded. 2. Fourier coefficients at each drive frequency were used to calculate the effective compliance (ratio of rotation and torque). The compliance has a sharp resonance when tonic, voluntary muscle activity is present. 3. The resonant frequency of compliance is between 3 and 8 Hz. The location of the resonant frequency and the magnitude of the compliance at resonance depend upon both the degree of tonic muscle activity and the amplitude of the driving torque. The resonant frequency increases with increasing tonic activity. 4. With tonic muscle activity, the compliance in the frequency range below resonance increases with increasing amplitudes of driving torque. 5. The e.m.g., when evoked by the rhythmic stretch, lags the start of stretching by between 50 and 70 msec. 6. When tonic muscle activity is present, the resonant frequency of the stretch reflex is between 5 and 6·5 Hz. 7. Following the start of driven oscillation at frequencies near resonance, slowly increasing amplitudes of angular rotation (to a limit) are observed. 8. Distortion (from the sinusoidal wave shape) of angular rotation is frequently observed with drive frequencies between 8 and 12 Hz during which there sometimes occur spontaneous recurrences of oscillation at the drive frequency. For the angular rotation, a significant portion of the power may be in subharmonic frequency components of the drive frequency when that frequency is between 8 and 12 Hz. 9. Self-sustaining oscillation (clonus) near the resonant frequency of the compliance is sometimes observed after the modulation signal to the motor is turned off. This is most often seen when the gastrocnemius—soleus muscles are fatigued. Clonus may be evoked by driven

  1. Provocative mechanical tests of the peripheral nervous system affect the joint torque-angle during passive knee motion.

    PubMed

    Andrade, R J; Freitas, S R; Vaz, J R; Bruno, P M; Pezarat-Correia, P

    2015-06-01

    This study aimed to determine the influence of the head, upper trunk, and foot position on the passive knee extension (PKE) torque-angle response. PKE tests were performed in 10 healthy subjects using an isokinetic dynamometer at 2°/s. Subjects lay in the supine position with their hips flexed to 90°. The knee angle, passive torque, surface electromyography (EMG) of the semitendinosus and quadriceps vastus medialis, and stretch discomfort were recorded in six body positions during PKE. The different maximal active positions of the cervical spine (neutral; flexion; extension), thoracic spine (neutral; flexion), and ankle (neutral; dorsiflexion) were passively combined for the tests. Visual analog scale scores and EMG were unaffected by body segment positioning. An effect of the ankle joint was verified on the peak torque and knee maximum angle when the ankle was in the dorsiflexion position (P < 0.05). Upper trunk positioning had an effect on the knee submaximal torque (P < 0.05), observed as an increase in the knee passive submaximal torque when the cervical and thoracic spines were flexed (P < 0.05). In conclusion, other apparently mechanical unrelated body segments influence torque-angle response since different positions of head, upper trunk, and foot induce dissimilar knee mechanical responses during passive extension. PMID:24941915

  2. Driving torque reduction in linkage mechanisms using joint compliance for robot head

    NASA Astrophysics Data System (ADS)

    Zhong, Chunhao; Yang, Xiaojun

    2015-09-01

    The conventional linkage mechanisms with compliant joint have been widely studied and implemented for increasing the adaptability of the mechanism to external contacts. However, the analysis of how compliant joints in linkage mechanism can reduce the energy consumption isn't still studied deeply. In a mobile service robot head, the actions of blinking the eyes and moving the eyeballs are realized by the planar linkage mechanism respectively. Therefore, minimizing the driving torques through motion trajectories for the linkage mechanism, which will be beneficial to extend the working time for mobile service robots. The dynamic modeling of the linkage mechanism with springs-loaded compliant joint is established. An optimization procedure for obtaining the optimal parameters of springs is proposed for minimizing the max value of driving torques within a range of desired operating conditions. The Simulations prove that the linkage mechanism with compliant joints can effectively reduce the driving torques, and reduce the energy consumption consequently. The framework can also be applied in other similar applications to reduce the driving torque and save energy. Compared with previous efforts, this is the first attempt that the linkage mechanism with complaint joint is applied in the robot head for reducing the driving torque.

  3. Torque Limit for Bolted Joint For Composites. Part B; Experimentation

    NASA Technical Reports Server (NTRS)

    Kostreva, Kristian M.

    2003-01-01

    Today, aerospace quality composite parts are generally made from either a unidirectional tape or a fabric prepreg form depending on the application. The matrix material, typically epoxy because of it dimensional stability, is pre-impregnated onto the fibers to ensure uniform distribution. Both of these composite forms are finding themselves used in applications where a joint is required. Two widely used joint methods are the classic mechanically fastened joint, and the contemporary bonded joint; however, the mechanically fastened joint is most commonly used by design engineers. A major portion of the research up-to-date about bolted composite joints has dealt with the inplane static load capacity. This work has helped to spawn standards dealing with filled-hole static joint strength. Other research has clearly shown that the clamp-up load in the mechanical fastener significantly affects the joint strength in a beneficial manner by reducing the bearing strength dependence of the composite laminate. One author reported a maximum increase in joint strength of 28%. This finding has helped to improve the reliability and efficiency of the joint in a composite structure.

  4. The development of goal-directed reaching in infants: hand trajectory formation and joint torque control.

    PubMed

    Konczak, J; Borutta, M; Topka, H; Dichgans, J

    1995-01-01

    Nine young infants were followed longitudinally from 4 to 15 months of age. We recorded early spontaneous movements and reaching movements to a stationary target. Time-position data of the hand (endpoint), shoulder, and elbow were collected using an optoelectronic measurement system (ELITE). We analyzed the endpoint kinematics and the intersegmental dynamics of the shoulder and elbow joint to investigate how changes in proximal torque control determined the development of hand trajectory formation. Two developmental phases of hand trajectory formation were identified: a first phase of rapid improvements between 16 and 24 weeks of age, the time of reaching onset for all infants. During that time period the number of movement units per reach and movement time decreased dramatically. In a second phase (28-64 weeks), a period of "fine-tuning" of the sensorimotor system, we saw slower, more gradual changes in the endpoint kinematics. The analysis of the underlying intersegmental joint torques revealed the following results: first, the range of muscular and motion-dependent torques (relative to body weight) did not change significantly with age. That is, early reaching was not confined by limitations in producing task-adequate levels of muscular torque. Second, improvements in the endpoint kinematics were not accomplished by minimizing amplitude of muscle and reactive torques. Third, the relative timing of muscular and motion-dependent torque peaks showed a systematic development toward an adult timing profile with increasing age. In conclusion, the development toward invariant characteristics of the hand trajectory is mirrored by concurrent changes in the control of joint forces. The acquisition of stable patterns of intersegmental coordination is not achieved by simply regulating force amplitude, but more so by modulating the correct timing of joint force production and by the system's use of reactive forces. Our findings support the view that development of reaching

  5. Comparison of regression models for estimation of isometric wrist joint torques using surface electromyography

    PubMed Central

    2011-01-01

    Background Several regression models have been proposed for estimation of isometric joint torque using surface electromyography (SEMG) signals. Common issues related to torque estimation models are degradation of model accuracy with passage of time, electrode displacement, and alteration of limb posture. This work compares the performance of the most commonly used regression models under these circumstances, in order to assist researchers with identifying the most appropriate model for a specific biomedical application. Methods Eleven healthy volunteers participated in this study. A custom-built rig, equipped with a torque sensor, was used to measure isometric torque as each volunteer flexed and extended his wrist. SEMG signals from eight forearm muscles, in addition to wrist joint torque data were gathered during the experiment. Additional data were gathered one hour and twenty-four hours following the completion of the first data gathering session, for the purpose of evaluating the effects of passage of time and electrode displacement on accuracy of models. Acquired SEMG signals were filtered, rectified, normalized and then fed to models for training. Results It was shown that mean adjusted coefficient of determination (Ra2) values decrease between 20%-35% for different models after one hour while altering arm posture decreased mean Ra2 values between 64% to 74% for different models. Conclusions Model estimation accuracy drops significantly with passage of time, electrode displacement, and alteration of limb posture. Therefore model retraining is crucial for preserving estimation accuracy. Data resampling can significantly reduce model training time without losing estimation accuracy. Among the models compared, ordinary least squares linear regression model (OLS) was shown to have high isometric torque estimation accuracy combined with very short training times. PMID:21943179

  6. Intramuscular pressure and torque during isometric, concentric and eccentric muscular activity

    NASA Technical Reports Server (NTRS)

    Styf, J.; Ballard, R.; Aratow, M.; Crenshaw, A.; Watenpaugh, D.; Hargens, A. R.

    1995-01-01

    Intramuscular pressures, electromyography (EMG) and torque generation during isometric, concentric and eccentric maximal isokinetic muscle activity were recorded in 10 healthy volunteers. Pressure and EMG activity were continuously and simultaneously measured side by side in the tibialis anterior and soleus muscles. Ankle joint torque and position were monitored continuously by an isokinetic dynamometer during plantar flexion and dorsiflexion of the foot. The increased force generation during eccentric muscular activity, compared with other muscular activity, was not accompanied by higher intramuscular pressure. Thus, this study demonstrated that eccentric muscular activity generated higher torque values for each increment of intramuscular pressure. Intramuscular pressures during antagonistic co-activation were significantly higher in the tibilis anterior muscle (42-46% of maximal agonistic activity) compared with the soleus muscle (12-29% of maximal agonistic activity) and was largely due to active recruitment of muscle fibers. In summary, eccentric muscular activity creates higher torque values with no additional increase of the intramuscular pressure compared with concentric and isometric muscular activity.

  7. Establishing a relationship between maximum torque production of isolated joints to simulate EVA ratchet push-pull maneuver: A case study

    NASA Technical Reports Server (NTRS)

    Pandya, Abhilash; Maida, James; Hasson, Scott; Greenisen, Michael; Woolford, Barbara

    1993-01-01

    As manned exploration of space continues, analytical evaluation of human strength characteristics is critical. These extraterrestrial environments will spawn issues of human performance which will impact the designs of tools, work spaces, and space vehicles. Computer modeling is an effective method of correlating human biomechanical and anthropometric data with models of space structures and human work spaces. The aim of this study is to provide biomechanical data from isolated joints to be utilized in a computer modeling system for calculating torque resulting from any upper extremity motions: in this study, the ratchet wrench push-pull operation (a typical extravehicular activity task). Established here are mathematical relationships used to calculate maximum torque production of isolated upper extremity joints. These relationships are a function of joint angle and joint velocity.

  8. Applied Joint-Space Torque and Stiffness Control of Tendon-Driven Fingers

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E.; Platt, Robert, Jr.; Wampler, Charles W.; Hargrave, Brian

    2010-01-01

    Existing tendon-driven fingers have applied force control through independent tension controllers on each tendon, i.e. in the tendon-space. The coupled kinematics of the tendons, however, cause such controllers to exhibit a transient coupling in their response. This problem can be resolved by alternatively framing the controllers in the joint-space of the manipulator. This work presents a joint-space torque control law that demonstrates both a decoupled and significantly faster response than an equivalent tendon-space formulation. The law also demonstrates greater speed and robustness than comparable PI controllers. In addition, a tension distribution algorithm is presented here to allocate forces from the joints to the tendons. It allocates the tensions so that they satisfy both an upper and lower bound, and it does so without requiring linear programming or open-ended iterations. The control law and tension distribution algorithm are implemented on the robotic hand of Robonaut-2.

  9. Dynamic modeling and optimal joint torque coordination of advanced robotic systems

    NASA Astrophysics Data System (ADS)

    Kang, Hee-Jun

    The development is documented of an efficient dynamic modeling algorithm and the subsequent optimal joint input load coordination of advanced robotic systems for industrial application. A closed-form dynamic modeling algorithm for the general closed-chain robotic linkage systems is presented. The algorithm is based on the transfer of system dependence from a set of open chain Lagrangian coordinates to any desired system generalized coordinate set of the closed-chain. Three different techniques for evaluation of the kinematic closed chain constraints allow the representation of the dynamic modeling parameters in terms of system generalized coordinates and have no restriction with regard to kinematic redundancy. The total computational requirement of the closed-chain system model is largely dependent on the computation required for the dynamic model of an open kinematic chain. In order to improve computational efficiency, modification of an existing open-chain KIC based dynamic formulation is made by the introduction of the generalized augmented body concept. This algorithm allows a 44 pct. computational saving over the current optimized one (O(N4), 5995 when N = 6). As means of resolving redundancies in advanced robotic systems, local joint torque optimization is applied for effectively using actuator power while avoiding joint torque limits. The stability problem in local joint torque optimization schemes is eliminated by using fictitious dissipating forces which act in the necessary null space. The performance index representing the global torque norm is shown to be satisfactory. In addition, the resulting joint motion trajectory becomes conservative, after a transient stage, for repetitive cyclic end-effector trajectories. The effectiveness of the null space damping method is shown. The modular robot, which is built of well defined structural modules from a finite-size inventory and is controlled by one general computer system, is another class of evolving

  10. The effects of joint torque, pace and work:rest ratio on powered hand tool operations.

    PubMed

    Lin, Jia-Hua; McGorry, Raymond W; Maikala, Rammohan V

    2012-01-01

    Repetitive use of hand-held power tools is associated with work-related upper extremity musculoskeletal disorders. Using a pneumatic nutrunner, 21 men completed twelve 360 repetitive fastener-driving sessions on three joints (hard, soft and control) at slow and fast pace, and two different work:rest patterns. Handgrip force and perceived exertions were collected throughout each session. For the control joint, the mean grip force exerted was 39.6% of maximum voluntary exertion (MVE) whereas during hard and soft joint sessions it was 48.9% MVE and 56.9% MVE, respectively. Throughout each session, the grip force decreased, more while operating soft and hard joints as compared with the control joint (regression slope: -0.022 and -0.023, compared with -0.007 N/drive, respectively), suggesting considerable upper extremity muscular effort by participants during torque buildup. Fast work pace resulted in higher average grip forces by participants but a greater decrease in the force as the session progressed. Providing rest breaks reduced perceived exertions. The findings gain additional knowledge for assembly task design to possibly reduce the hand/arm injury risks for the operator. Practitioner Summary: Powered hand tools are widely used in assembly and manufacturing industries. However, the nature of their repetitive use on human operator biomechanical and perceptual responses is not fully understood. This study examined work-related risk factors such as joint torque, pace and work:rest ratios on powered hand tool performance. PMID:22409173

  11. Postural control and torque of the knee joint after healed tibial shaft fracture.

    PubMed

    Karladani, A H; Svantesson, U; Granhed, H; Styf, J

    2001-01-01

    Muscular atrophy occurs as a consequence of trauma and immobilisation. This cohort comparison study was conducted to evaluate the limb function after healed tibial shaft fractures, which were treated by casting versus nailing. Balance (as centre of pressure) and muscle strength (as torque of the knee joint during knee extension) have been measured in 27 patients with tibial shaft fractures with a mean age of 39 (19-73) years, 1 year after fracture healing. Fourteen patients were treated by intramedullary nailing 'nailed group' and 13 by plaster cast with or without minimal internal fixation 'casted group'. Centre of pressure was measured on a force platform. Knee extension torque was measured during isometric and concentric muscle actions by an isokinetic dynamometer. Centre of pressure tended to be more towards the uninjured leg in patients who had been treated by plaster cast (P<0.05). Side-to-side differences for isometric torque were significantly higher within the casted group (P<0.05). Patients with tibial shaft fractures treated by intramedullary nailing showed better postural control, one-leg standing test, and side-to-side differences for isometric muscle strength compared with patients treated by cast. Therefore, we recommend intramedullary nailing as a better method of treatment for tibial shaft fractures, with regard to recovery of muscle function. PMID:11164404

  12. Development of Torque Sensor with High Sensitivity for Joint of Robot Manipulator Using 4-Bar Linkage Shape

    PubMed Central

    Zhang, Hong-Xia; Ryoo, Young-Jae; Byun, Kyung-Seok

    2016-01-01

    The torque sensor is used to measure the joint torque of a robot manipulator. Previous research showed that the sensitivity and the stiffness of torque sensors have trade-off characteristics. Stiffness has to be sacrificed to increase the sensitivity of the sensor. In this research, a new torque sensor with high sensitivity (TSHS) is proposed in order to resolve this problem. The key idea of the TSHS comes from its 4-bar linkage shape in which the angular displacement of a short link is larger than that of a long link. The sensitivity of the torque sensor with a 4-bar link shape is improved without decreasing stiffness. Optimization techniques are applied to maximize the sensitivity of the sensor. An actual TSHS is constructed to verify the validity of the proposed mechanism. Experimental results show that the sensitivity of TSHS can be increased 3.5 times without sacrificing stiffness. PMID:27376304

  13. Development of Torque Sensor with High Sensitivity for Joint of Robot Manipulator Using 4-Bar Linkage Shape.

    PubMed

    Zhang, Hong-Xia; Ryoo, Young-Jae; Byun, Kyung-Seok

    2016-01-01

    The torque sensor is used to measure the joint torque of a robot manipulator. Previous research showed that the sensitivity and the stiffness of torque sensors have trade-off characteristics. Stiffness has to be sacrificed to increase the sensitivity of the sensor. In this research, a new torque sensor with high sensitivity (TSHS) is proposed in order to resolve this problem. The key idea of the TSHS comes from its 4-bar linkage shape in which the angular displacement of a short link is larger than that of a long link. The sensitivity of the torque sensor with a 4-bar link shape is improved without decreasing stiffness. Optimization techniques are applied to maximize the sensitivity of the sensor. An actual TSHS is constructed to verify the validity of the proposed mechanism. Experimental results show that the sensitivity of TSHS can be increased 3.5 times without sacrificing stiffness. PMID:27376304

  14. Torque Limit for Bolted Joint for Composites. Part A; TTTC Properties of Laminated Composites

    NASA Technical Reports Server (NTRS)

    Zhao, Yi

    2003-01-01

    The existing design code for torque limit of bolted joints for composites at Marshall Space Flight Center is MSFC-STD-486B, which was originally developed in 1960s for metallic materials. The theoretical basis for this code was a simplified mechanics analysis, which takes into account only the bolt, nut and washers, but not the structural members to be connected. The assumption was that metallic materials would not fail due to the bearing stress at the contact area between washer and the mechanical member. This is true for metallic materials; but for composite materials the results could be completely different. Unlike most metallic materials, laminated composite materials have superior mechanical properties (such as modulus and strength) in the in-plane direction, but not in the out-of-plane, or through-the-thickness (TTT) direction. During the torquing, TTT properties (particularly compressive modulus and compressive strength) play a dominant role in composite failure. Because of this concern, structural design engineers at Marshall are currently using a compromised empirical approach: using 50% of the torque value for composite members. Companies like Boeing is using a similar approach. An initial study was conducted last summer on this topic to develop theoretical model(s) that takes into consideration of composite members. Two simplified models were developed based on stress failure criterion and strain failure criterion, respective. However, these models could not be used to predict the torque limit because of the unavailability of material data, specifically, through-the-thickness compression (TTTC) modulus and strength. Therefore, the task for this summer is to experimentally determine the TTTC properties. Due to the time limitation, only one material has been tested: IM7/8552 with [0 degrees,plus or minus 45 degrees, 90 degree ] configuration. This report focuses the test results and their significance, while the experimentation will be described in a

  15. Torques generated at the human elbow joint in response to constant position errors imposed during voluntary movements.

    PubMed

    Bennett, D J

    1993-01-01

    The stiffness of the human elbow joint was investigated during targeted, 1.0-rad voluntary flexion movements at speeds ranging from slow (1.5 rad/s) to very fast (6.0 rad/s). A torque motor produced controlled step position errors in the execution of the movements. The steps began at the onset of movement, rose to an amplitude of 0.15 rad in 100 ms, and had a duration equal to movement duration. The net joint torque (muscle torque) resisting the step perturbation was computed from the applied torque, the joint acceleration, and the limb inertia. Subjects resisted the imposed step changes with approximately step changes in the net muscle torque. The mean resistance torque divided by the step amplitude was computed and is referred to as the stiffness. The stiffness increased with the voluntary movement speed, over the range of speeds (1.5-6 rad/s). The stiffness increased linearly with the magnitude of the net muscle torque on the unperturbed trials (referred to as "background torque"). The stiffness changed by only 20% when the step amplitude ranged from 0.05 to 0.15 rad. The mechanical resonant frequency (fr), estimated from the average stiffness estimates, ranged from 0.8 to 3.0 Hz. The resonant frequency approximately equaled the principal frequency component of the movement fm. On average: fr = 0.96 fm +0.46. During the fixed, 100-ms rise time of the step, the resistance was not linearly related to the background torque. At slower speeds the resistance was relatively greater during this rise time. However, when the imposed step perturbation was modified so that its rise time occurred in a time proportional to the movement duration (rather than in the fixed, 100-ms, time), the muscle torque resisting the motor during this rise time was proportional to the background torque. When these modified step responses were plotted on a time scale normalized to the movement duration, they all had approximately the same shape. Apparently the muscle viscosity scaled with the

  16. Control strategy for stabilizing force with goal-equivalent joint torques is frequency-dependent during human hopping.

    PubMed

    Yen, Jasper T; Chang, Young-Hui

    2009-01-01

    Normal human locomotion requires the ability to control a complex, redundant neuromechanical system to repetitively cycle the legs in a stable manner. In a reduced paradigm of locomotion, hopping, we investigated the ability of human subjects to exploit motor redundancy in the legs to coordinate joint torques fluctuations to minimize force fluctuations generated against the ground. Although we saw invariant performance in terms of force stabilization across frequencies, we found that the role of joint torque coordination in stabilizing force was most important at slow hopping frequencies. Notably, the role of this coordinated variation strategy decreased as hopping frequency increased, giving way to an independent joint variation strategy. At high frequencies, the control strategy to stabilize force was more dependent on a direct reduction in ankle torque fluctuations. Through the systematic study of how joint-level variances affect task-level end-point function, we can gain insight into the underlying control strategies in place for automatically counteracting cycle-to-cycle deviations during normal human locomotion. PMID:19964783

  17. Estimations of relative effort during sit-to-stand increase when accounting for variations in maximum voluntary torque with joint angle and angular velocity.

    PubMed

    Bieryla, Kathleen A; Anderson, Dennis E; Madigan, Michael L

    2009-02-01

    The main purpose of this study was to compare three methods of determining relative effort during sit-to-stand (STS). Fourteen young (mean 19.6+/-SD 1.2 years old) and 17 older (61.7+/-5.5 years old) adults completed six STS trials at three speeds: slow, normal, and fast. Sagittal plane joint torques at the hip, knee, and ankle were calculated through inverse dynamics. Isometric and isokinetic maximum voluntary contractions (MVC) for the hip, knee, and ankle were collected and used for model parameters to predict the participant-specific maximum voluntary joint torque. Three different measures of relative effort were determined by normalizing STS joint torques to three different estimates of maximum voluntary torque. Relative effort at the hip, knee, and ankle were higher when accounting for variations in maximum voluntary torque with joint angle and angular velocity (hip=26.3+/-13.5%, knee=78.4+/-32.2%, ankle=27.9+/-14.1%) compared to methods which do not account for these variations (hip=23.5+/-11.7%, knee=51.7+/-15.0%, ankle=20.7+/-10.4%). At higher velocities, the difference in calculating relative effort with respect to isometric MVC or incorporating joint angle and angular velocity became more evident. Estimates of relative effort that account for the variations in maximum voluntary torque with joint angle and angular velocity may provide higher levels of accuracy compared to methods based on measurements of maximal isometric torques. PMID:17720539

  18. Relationship between navicular drop and measuring position of maximal plantar flexion torque of the first and second-fifth metatarsophalangeal joints

    PubMed Central

    Saeki, Junya; Tojima, Michio; Torii, Suguru

    2015-01-01

    [Purpose] The purpose of this study was to determine the relationship between navicular drop and plantar flexion torque of the first and second-fifth metatarsophalangeal joints. [Subjects] Ten healthy young men participated in this study. [Methods] The Pearson product-moment correlation coefficient was calculated to determine the relationship between navicular drop and plantar flexion torque of the first and second-fifth metatarsophalangeal joints. [Results] Significant negative correlations were observed between navicular drop and plantar flexion torques in the lengthened position of the intrinsic toe plantar flexion muscles, but no correlations were found between navicular drop and plantar flexion torques in the neutral position of the ankle and metatarsophalangeal joints. Moreover, the intrinsic toe plantar flexion muscles were found to contribute to the formation of the medial longitudinal arch. [Conclusion] Navicular drop correlates with metatarsophalangeal joint muscle strength in plantar flexion where the intrinsic toe muscles are capable of exerting force. PMID:26180323

  19. Relationship between navicular drop and measuring position of maximal plantar flexion torque of the first and second-fifth metatarsophalangeal joints.

    PubMed

    Saeki, Junya; Tojima, Michio; Torii, Suguru

    2015-06-01

    [Purpose] The purpose of this study was to determine the relationship between navicular drop and plantar flexion torque of the first and second-fifth metatarsophalangeal joints. [Subjects] Ten healthy young men participated in this study. [Methods] The Pearson product-moment correlation coefficient was calculated to determine the relationship between navicular drop and plantar flexion torque of the first and second-fifth metatarsophalangeal joints. [Results] Significant negative correlations were observed between navicular drop and plantar flexion torques in the lengthened position of the intrinsic toe plantar flexion muscles, but no correlations were found between navicular drop and plantar flexion torques in the neutral position of the ankle and metatarsophalangeal joints. Moreover, the intrinsic toe plantar flexion muscles were found to contribute to the formation of the medial longitudinal arch. [Conclusion] Navicular drop correlates with metatarsophalangeal joint muscle strength in plantar flexion where the intrinsic toe muscles are capable of exerting force. PMID:26180323

  20. Effects of Low-Impact Dance on Blood Biochemistry, Bone Mineral Density, the Joint Range of Motion of Lower Extremities, Knee Extension Torque, and Fall in Females.

    PubMed

    Wu, Hui Ying; Tu, Jui Hung; Hsu, Chin Hsing; Tsao, Te Hung

    2016-01-01

    The effect of low-impact dance on blood metabolites, the joint range of motion (ROM) of the lower extremities, knee extension torque, bone mass density (BMD), the number of falls, and the confidence to perform daily activities (Modified Falls Efficacy Scale [MFES]) was examined in older sedentary women (age: 59 ± 4 years) before and after a 16-week intervention. Results showed that the average score for the MFES, some parameters of blood chemistry, and joint ROM were significantly improved after low-impact intervention. In addition to improvements in blood lipids and body fat percentages, the increases shown in the parameters regarding the lower extremities may contribute to confidence in performing common daily activities in older women, although the number of falls did not significantly differ between the two groups during the 16-week period. PMID:25642949

  1. The effect of shoulder core exercises on isometric torque of glenohumeral joint movements in healthy young females

    PubMed Central

    Moghadam, Afsun Nodehi; Mohammadi, Roghayeh; Arab, Amir Massoud; Kazamnajad, Anoshirvan

    2011-01-01

    BACKGROUND: Strength improvement of the shoulder muscles is a major goal in rehabilitation or athletic conditioning programs. The purpose of this study was to determine the effect of shoulder core exercises on the isometric torque of glenohumeral joint movements. METHODS: A total of 36 healthy females with no history of shoulder injury enrolled in this study. Subjects were randomly assigned into the control group (n = 18, 22 ± 2.19 years of age) or experimental group (n = 18, 21 ± 2.05 years of age). Subjects in experimental group performed shoulder core exercises, using progressive resistance training, three times a week for six weeks. Subjects in control group performed no exercise. The isometric torque of shoulder movements were measured with Dynatorq device in isolated test positions of glenohumeral muscles at the beginning and after six weeks in both groups. RESULTS: shoulder core exercise training led to an increase in maximal isometric torques of shoulder scaption at 0° and 90° arm elevation, external and internal rotation, horizontal adduction and extension movements (p < 0.001 in all instances). No significant difference was found between initial scores and scores after six weeks in the control group (p > 0.05). CONCLUSIONS: These findings indicated that shoulder core exercise training leads to an increase in peak torque for all glenohumeral movements that can be considered in glenohumeral muscles strengthening programs. PMID:22973363

  2. Torque-Limiting Infinitely-Variable CAM Release Mechanism for a Rotatable Joint

    NASA Technical Reports Server (NTRS)

    Moetteli, John B. (Inventor)

    1997-01-01

    The invention relates to a mechanism for permitting convenient manual or servo-powered control of a boom assembly, which is rotatably positionable about yaw and pitch axes by means of releasably locking, yaw and pitch torque-limiting mechanisms, each of which may be locked, unlocked, and positioned by respective yaw and pitch levers. The boom may be longitudinally projected and withdrawn by rotating a boom extension/retraction crank. Torque limiting is provided by spring loaded clutch mechanisms, whereby positioning forces applied to the handles are effective to move the boom unless overcome by greater opposing forces, sufficient to overcome the torque applied by the torque limiting clutch mechanisms. In operation, a structure positionable by the invention (e.g., and end-effector or robot arm) may be rotatably moved about yaw and pitch axes by moving a selected one of the three levers.

  3. Development of infant leg coordination: Exploiting passive torques.

    PubMed

    Sargent, Barbara; Scholz, John; Reimann, Hendrik; Kubo, Masayoshi; Fetters, Linda

    2015-08-01

    Leg joint coordination systematically changes over the first months of life, yet there is minimal data on the underlying change in muscle torques that might account for this change in coordination. The purpose of this study is to investigate the contribution of torque changes to early changes in leg joint coordination. Kicking actions were analyzed of 10 full-term infants between 6 and 15-weeks of age using three-dimensional kinematics and kinetics. We found 11 of 15 joint angle pairs demonstrated a change from more in-phase intralimb coordination at 6-weeks to less in-phase coordination at 15-weeks. Although the magnitude of joint torques normalized to the mass of the leg remained relatively consistent, we noted more complex patterns of torque component contribution across ages. By focusing on the change in torques associated with hip-knee joint coordination, we found that less in-phase hip-knee joint coordination at 15-weeks was associated with decreased influence of knee muscle torque and increased influence of knee gravitational and motion-dependent torques, supporting that infants coordinate hip muscle torque with passive knee gravitational and motion-dependent torques to generate kicks with reduced active knee muscle torque. We propose that between 6 and 15-weeks of age less in-phase hip-knee coordination emerges as infants exploit passive dynamics in the coordination of hip and knee motions. PMID:26117493

  4. Does sensorimotor cortex activity change with quadriceps femoris torque output? A human electroencephalography study.

    PubMed

    Fry, A; Vogt, T; Folland, J P

    2014-09-01

    Encoding muscular force output during voluntary contractions is widely perceived to result, at least in part, from modulations in neuronal activity within the sensorimotor cortex. However the underlying electrophysiological phenomena associated with increased force output remains unclear. This study directly assessed sensorimotor cortex activity using electroencephalography (EEG) in humans performing isometric knee-extensions at a range of discrete torque levels. Fifteen healthy males (age 24 (s=5) years) completed one familiarization and one experimental trial. Participants performed a cyclic series of 60 isometric knee-extension contractions with the right leg, including 15 contractions of a 5-s duration at each of four discrete torque levels: 15%, 30%, 45% and 60% of maximal voluntary torque (MVT). Isometric knee-extension torque, quadriceps electromyography and EEG were recorded at rest and throughout all the contractions. EEG (0.5-50 Hz) was collected using a 32-channel active-electrode cap. A voxel-based low-resolution brain electromagnetic tomography (LORETA) analysis calculated cortical activation within the sensorimotor cortex (one of 27 MNI coordinates) for the entire 0.5-50-Hz range (cortical current density (CCD)), as well as for each constituent frequency band in this range (delta, theta, alpha, beta and gamma). Gamma band (30-50 Hz) cortical activity increased with contraction torque (analysis of variance [ANOVA], P=0.03). Conversely, activity within the other frequency bands was not modulated by torque (P≥0.09), nor was overall CCD (P=0.11). Peripheral neuromuscular activation (quadriceps electromyography (EMG) amplitude) demonstrated distinct increases between each torque level (P<0.01). In conclusion, sensorimotor cortical activity within the gamma band demonstrated an overall increase with contraction torque, whereas both CCD and each of the other constituent frequency bands were not modulated by increments in torque magnitude during isometric

  5. Preparatory Body State before Reacting to an Opponent: Short-Term Joint Torque Fluctuation in Real-Time Competitive Sports

    PubMed Central

    Fujii, Keisuke; Yamashita, Daichi; Kimura, Tetsuya; Isaka, Tadao; Kouzaki, Motoki

    2015-01-01

    In a competitive sport, the outcome of a game is determined by an athlete’s relationship with an unpredictable and uncontrolled opponent. We have previously analyzed the preparatory state of ground reaction forces (GRFs) dividing non-weighted and weighted states (i.e., vertical GRFs below and above 120% of body weight, respectively) in a competitive ballgame task and demonstrated that the non-weighted state prevented delay of the defensive step and promoted successful guarding. However, the associated kinetics of lower extremity joints during a competitive sports task remains unknown. The present study aims to investigate the kinetic characteristics of a real-time competitive sport before movement initiation. As a first kinetic study on a competitive sport, we initially compared the successful defensive kinetics with a relatively stable preparatory state and the choice-reaction sidestep as a control movement. Then, we investigated the kinetic cause of the outcome in a 1-on-1 dribble in terms of the preparatory states according to our previous study. The results demonstrated that in successful defensive motions in the non-weighted state guarding trial, the times required for the generation of hip abduction and three extension torques for the hip, knee, and ankle joints were significantly shortened compared with the choice-reaction sidestep, and hip abduction and hip extension torques were produced almost simultaneously. The sport-specific movement kinetics emerges only in a more-realistic interactive experimental setting. A comparison of the outcomes in the 1-on-1 dribble and preparatory GRF states showed that, in the non-weighted state, the defenders guarded successfully in 68.0% of the trials, and the defender’s initiation time was earlier than that in the weighted state (39.1%). In terms of kinetics, the root mean squares of the derivative of hip abduction and three extension torques in the non-weighted state were smaller than those in the weighted state

  6. Integrated Design of an Active Torque Balancing Mechanism and a Planetary Gear Reducer

    NASA Astrophysics Data System (ADS)

    Sun, Jing; Yao, Yanan

    In this paper, a novel concept of integrating an active torque balancing mechanism with a planetary gear reducer is presented. This integrated device is composed of a speed reduction unit and a torque compensation unit. The speed reduction unit, which contains a two-stage planetary gear train, can make the device to transform the speed and torque for meeting the needed requirements of the machine. The torque compensation unit, which consists of a differential gear train and a servo motor, can make the device to balance the input torque fluctuations of the mechanical system. Through an analytical method, an exact control function which can totally eliminate the input torque fluctuation of the driving motor of the machine is derived for the servo motor of the integrated device. At the same time, by adjusting the structure parameters of the differential gear train, the torque fluctuation of the servo motor can be limited too. Besides, in order to obtain a satisfactory tradeoff between the torque fluctuations of the driving motor and the servo motor, an optimization method is developed to find an appropriate control function for the servo motor. In addition, an integrated approach is proposed to optimize both the structure parameters of the differential gear train and the control function of the servo motor. Two numerical examples are given to illustrate the design procedures and to show their feasibilities.

  7. Active Joint Mechanism Driven by Multiple Actuators Made of Flexible Bags: A Proposal of Dual Structural Actuator

    PubMed Central

    Inou, Norio

    2013-01-01

    An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input. PMID:24385868

  8. Active joint mechanism driven by multiple actuators made of flexible bags: a proposal of dual structural actuator.

    PubMed

    Kimura, Hitoshi; Matsuzaki, Takuya; Kataoka, Mokutaro; Inou, Norio

    2013-01-01

    An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input. PMID:24385868

  9. Comparative study of torque expression among active and passive self-ligating and conventional brackets

    PubMed Central

    Franco, Érika Mendonça Fernandes; Valarelli, Fabrício Pinelli; Fernandes, João Batista; Cançado, Rodrigo Hermont; de Freitas, Karina Maria Salvatore

    2015-01-01

    Abstract Objective: The aim of this study was to compare torque expression in active and passive self-ligating and conventional brackets. Methods: A total of 300 segments of stainless steel wire 0.019 x 0.025-in and six different brands of brackets (Damon 3MX, Portia, In-Ovation R, Bioquick, Roth SLI and Roth Max) were used. Torque moments were measured at 12°, 24°, 36° and 48°, using a wire torsion device associated with a universal testing machine. The data obtained were compared by analysis of variance followed by Tukey test for multiple comparisons. Regression analysis was performed by the least-squares method to generate the mathematical equation of the optimal curve for each brand of bracket. Results: Statistically significant differences were observed in the expression of torque among all evaluated bracket brands in all evaluated torsions (p < 0.05). It was found that Bioquick presented the lowest torque expression in all tested torsions; in contrast, Damon 3MX bracket presented the highest torque expression up to 36° torsion. Conclusions: The connection system between wire/bracket (active, passive self-ligating or conventional with elastic ligature) seems not to interfere in the final torque expression, the latter being probably dependent on the interaction between the wire and the bracket chosen for orthodontic mechanics. PMID:26691972

  10. Suspending and Reinstating Joint Activities with Dialogue

    ERIC Educational Resources Information Center

    Chevalley, Eric; Bangerter, Adrian

    2010-01-01

    Interruptions are common in joint activities like conversations. Typically, interrupted participants suspend the activity, address the interruption, and then reinstate the activity. In conversation, people jointly commit to interact and to talk about a topic, establishing these commitments sequentially. When a commitment is suspended, face is…

  11. Medial gastrocnemius muscle fascicle active torque-length and Achilles tendon properties in young adults with spastic cerebral palsy.

    PubMed

    Barber, Lee; Barrett, Rod; Lichtwark, Glen

    2012-10-11

    Individuals with spastic cerebral palsy (CP) typically experience muscle weakness. The mechanisms responsible for muscle weakness in spastic CP are complex and may be influenced by the intrinsic mechanical properties of the muscle and tendon. The purpose of this study was to investigate the medial gastrocnemius (MG) muscle fascicle active torque-length and Achilles tendon properties in young adults with spastic CP. Nine relatively high functioning young adults with spastic CP (GMFCS I, 17±2 years) and 10 typically developing individuals (18±2 years) participated in the study. Active MG torque-length and Achilles tendon properties were assessed under controlled conditions on a dynamometer. EMG was recorded from leg muscles and ultrasound was used to measure MG fascicle length and Achilles tendon length during maximal isometric contractions at five ankle angles throughout the available range of motion and during passive rotations imposed by the dynamometer. Compared to the typically developing group, the spastic CP group had 33% lower active ankle plantarflexion torque across the available range of ankle joint motion, partially explained by 37% smaller MG muscle and 4% greater antagonistic co-contraction. The Achilles tendon slack length was also 10% longer in the spastic CP group. This study confirms young adults with mild spastic CP have altered muscle-tendon mechanical properties. The adaptation of a longer Achilles tendon may facilitate a greater storage and recovery of elastic energy and partially compensate for decreased force and work production by the small muscles of the triceps surae during activities such as locomotion. PMID:22867763

  12. Analysis of joint force and torque for the human and non-human ape foot during bipedal walking with implications for the evolution of the foot.

    PubMed

    Wang, Weijie; Abboud, Rami J; Günther, Michael M; Crompton, Robin H

    2014-08-01

    The feet of apes have a different morphology from those of humans. Until now, it has merely been assumed that the morphology seen in humans must be adaptive for habitual bipedal walking, as the habitual use of bipedal walking is generally regarded as one of the most clear-cut differences between humans and apes. This study asks simply whether human skeletal proportions do actually enhance foot performance during human-like bipedalism, by examining the influence of foot proportions on force, torque and work in the foot joints during simulated bipedal walking. Skeletons of the common chimpanzee, orangutan, gorilla and human were represented by multi-rigid-body models, where the components of the foot make external contact via finite element surfaces. The models were driven by identical joint motion functions collected from experiments on human walking. Simulated contact forces between the ground and the foot were found to be reasonably comparable with measurements made during human walking using pressure- and force-platforms. Joint force, torque and work in the foot were then predicted. Within the limitations of our model, the results show that during simulated human-like bipedal walking, (1) the human and non-human ape (NHA) feet carry similar joint forces, although the distributions of the forces differ; (2) the NHA foot incurs larger joint torques than does the human foot, although the human foot has higher values in the first tarso-metatarsal and metatarso-phalangeal joints, whereas the NHA foot incurs higher values in the lateral digits; and (3) total work in the metatarso-phalangeal joints is lower in the human foot than in the NHA foot. The results indicate that human foot proportions are indeed well suited to performance in normal human walking. PMID:24925580

  13. Analysis of joint force and torque for the human and non-human ape foot during bipedal walking with implications for the evolution of the foot

    PubMed Central

    Wang, Weijie; Abboud, Rami J; Günther, Michael M; Crompton, Robin H

    2014-01-01

    The feet of apes have a different morphology from those of humans. Until now, it has merely been assumed that the morphology seen in humans must be adaptive for habitual bipedal walking, as the habitual use of bipedal walking is generally regarded as one of the most clear-cut differences between humans and apes. This study asks simply whether human skeletal proportions do actually enhance foot performance during human-like bipedalism, by examining the influence of foot proportions on force, torque and work in the foot joints during simulated bipedal walking. Skeletons of the common chimpanzee, orangutan, gorilla and human were represented by multi-rigid-body models, where the components of the foot make external contact via finite element surfaces. The models were driven by identical joint motion functions collected from experiments on human walking. Simulated contact forces between the ground and the foot were found to be reasonably comparable with measurements made during human walking using pressure- and force-platforms. Joint force, torque and work in the foot were then predicted. Within the limitations of our model, the results show that during simulated human-like bipedal walking, (1) the human and non-human ape (NHA) feet carry similar joint forces, although the distributions of the forces differ; (2) the NHA foot incurs larger joint torques than does the human foot, although the human foot has higher values in the first tarso-metatarsal and metatarso-phalangeal joints, whereas the NHA foot incurs higher values in the lateral digits; and (3) total work in the metatarso-phalangeal joints is lower in the human foot than in the NHA foot. The results indicate that human foot proportions are indeed well suited to performance in normal human walking. PMID:24925580

  14. Thermally activated switching of perpendicular magnet by spin-orbit spin torque

    SciTech Connect

    Lee, Ki-Seung; Lee, Seo-Won; Min, Byoung-Chul; Lee, Kyung-Jin

    2014-02-17

    We theoretically investigate the threshold current for thermally activated switching of a perpendicular magnet by spin-orbit spin torque. Based on the Fokker-Planck equation, we obtain an analytic expression of the switching current, in agreement with numerical result. We find that thermal energy barrier exhibits a quasi-linear dependence on the current, resulting in an almost linear dependence of switching current on the log-scaled current pulse-width even below 10 ns. This is in stark contrast to standard spin torque switching, where thermal energy barrier has a quadratic dependence on the current and the switching current rapidly increases at short pulses. Our results will serve as a guideline to design and interpret switching experiments based on spin-orbit spin torque.

  15. A method to accurately estimate the muscular torques of human wearing exoskeletons by torque sensors.

    PubMed

    Hwang, Beomsoo; Jeon, Doyoung

    2015-01-01

    In exoskeletal robots, the quantification of the user's muscular effort is important to recognize the user's motion intentions and evaluate motor abilities. In this paper, we attempt to estimate users' muscular efforts accurately using joint torque sensor which contains the measurements of dynamic effect of human body such as the inertial, Coriolis, and gravitational torques as well as torque by active muscular effort. It is important to extract the dynamic effects of the user's limb accurately from the measured torque. The user's limb dynamics are formulated and a convenient method of identifying user-specific parameters is suggested for estimating the user's muscular torque in robotic exoskeletons. Experiments were carried out on a wheelchair-integrated lower limb exoskeleton, EXOwheel, which was equipped with torque sensors in the hip and knee joints. The proposed methods were evaluated by 10 healthy participants during body weight-supported gait training. The experimental results show that the torque sensors are to estimate the muscular torque accurately in cases of relaxed and activated muscle conditions. PMID:25860074

  16. Examination of the torque required to passively palmar abduct the thumb CMC joint in a pediatric population with hemiplegia and stroke.

    PubMed

    Stirling, Leia; Ahmad, Mona Qureshi; Kelty-Stephen, Damian; Correia, Annette

    2015-12-16

    Many activities of daily living involve precision grasping and bimanual manipulation, such as putting toothpaste on a toothbrush or feeding oneself. However, children afflicted by stroke, cerebral palsy, or traumatic brain injury may have lost or never had the ability to actively and accurately control the thumb. To translate insights from adult rehabilitation robotics to innovative therapies for hand rehabilitation in pediatric care, specifically for thumb deformities, an understanding of the torque needed to abduct the thumb to assist grasping tasks is required. Participants (n=16, 10 female, 13.2±3.1 years) had an upper extremity evaluation and measures were made of their passive range of motion, anthropometrics, and torques to abduct the thumb for both their affected and non-affected sides. Torque measures were made using a custom wrist orthosis that was adjusted for each participant. The torque to achieve maximum abduction was 1.47±0.61inlb for the non-affected side and 1.51±0.68inlb for the affected side, with a maximum recorded value of 4.87inlb. The overall maximum applied torque was observed during adduction and was 5.10inlb. We saw variation in the applied torque, which could have been due to the applied torques by the Occupational Therapist or the participant actively assisting or resisting the motion rather than remaining passive. We expect similar muscle and participant variation to exist with an assistive device. Thus, the data presented here can be used to inform the specifications for the development of an assistive thumb orthosis for children with "thumb-in-palm" deformity. PMID:26542786

  17. Within- and between-session reliability of the maximal voluntary knee extension torque and activation.

    PubMed

    Park, Jihong; Hopkins, J Ty

    2013-01-01

    A ratio between the torque generated by maximal voluntary isometric contraction (MVIC) and exogenous electrical stimulus, central activation ratio (CAR), has been widely used to assess quadriceps function. To date, no data exist regarding between-session reliability of this measurement. Thirteen neurologically sound volunteers underwent three testing sessions (three trials per session) with 48 hours between-session. Subjects performed MVICs of the quadriceps with the knee locked at 90° flexion and the hip at 85°. Once the MVIC reached a plateau, an electrical stimulation from superimposed burst technique (SIB: 125 V with peak output current 450 mA) was manually delivered and transmitted directly to the quadriceps via stimulating electrodes. CAR was calculated by using the following equation: CAR = MVIC torque/MVIC + SIB torque. Intraclass correlation coefficients (ICC) were calculated within- (ICC((2,1))) and between-session (ICC((2,k))) for MVIC torques and CAR values. Our data show that quadriceps MVIC and CAR are very reliable both within- (ICC((2,1)) = 0.99 for MVIC; 0.94 for CAR) and between-measurement sessions (ICC((2,k)) = 0.92 for MVIC; 0.86 for CAR) in healthy young adults. For clinical research, more data of the patients with pathological conditions are required to ensure reproducibility of calculation of CAR. PMID:23009562

  18. Firing of antagonist small-diameter muscle afferents reduces voluntary activation and torque of elbow flexors.

    PubMed

    Kennedy, David S; McNeil, Chris J; Gandevia, Simon C; Taylor, Janet L

    2013-07-15

    During muscle fatigue, firing of small-diameter muscle afferents can decrease voluntary activation of the fatigued muscle. However, these afferents may have a more widespread effect on other muscles in the exercising limb. We examined if the firing of fatigue-sensitive afferents from elbow extensor muscles in the same arm reduces torque production and voluntary activation of elbow flexors. In nine subjects we examined voluntary activation of elbow flexors by measuring changes in superimposed twitches evoked by transcranial magnetic stimulation of the motor cortex during brief (2-3 s) maximal voluntary contractions (MVC). Inflation of a blood pressure cuff following a 2-min sustained MVC blocked blood flow to the fatigued muscle and maintained firing of small-diameter afferents. After a fatiguing elbow flexion contraction, maximal flexion torque was lower (26.0 ± 4.4% versus 67.9 ± 5.2% of initial maximal torque; means ± s.d.; P < 0.001) and superimposed twitches were larger (4.1 ± 1.1% versus 1.8 ± 0.2% ongoing MVC, P = 0.01) with than without ischaemia. After a fatiguing elbow extensor contraction, maximal flexion torque was also reduced (82.2 ± 4.9% versus 91.4 ± 2.3% of initial maximal torque; P = 0.007), superimposed twitches were larger (2.7 ± 0.7% versus 1.3 ± 0.2% ongoing MVC; P = 0.02) and voluntary activation lower (81.6 ± 8.2% versus 95.5 ± 6.9%; P = 0.04) with than without ischaemia. After a fatiguing contraction, voluntary drive to the fatigued muscles is reduced with continued input from small-diameter muscle afferents. Furthermore, fatigue of the elbow extensor muscles decreases voluntary drive to unfatigued elbow flexors of the same arm. Therefore, firing of small-diameter muscle afferents from one muscle can affect voluntary activation and hence torque generation of another muscle in the same limb. PMID:23652589

  19. The 2001 April Burst Activation of SGR 1900-14: Pulse Properties and Torque

    NASA Technical Reports Server (NTRS)

    Woods, P. M.; Kouveliotou, C.; Goegues, E.; Finger, M. H.; Feroci, M.; Mereghetti, S.; Swank, J. H.; Hurley, K.; Heise, J.; Smith D.

    2003-01-01

    We report on observations of SGR 1900+14 made with the Rossi X-Ray Timing Explorer (RXTE) and BeppoSAXduring the 2001 April burst activation of the source. Using these data, we measure the spin-down torque on the star and confirm earlier findings that the torque and burst activity are not directly correlated. We compare the X-ray pulse profile to the gamma-ray profile during the April 18 intermediate flare and show that (1) their shapes are similar and (1) the gamma-ray profile aligns closely in phase with the X-ray pulsations. The good phase alignment of the gamma-ray and X-ray profiles suggests that there was no rapid spin-down following this flare of the magnitude inferred for the August 27 giant flare. We discuss how these observations further constrain magnetic field reconfiguration models for the large flares of SGRs.

  20. Physical Activity After Total Joint Arthroplasty

    PubMed Central

    Vogel, Laura A.; Carotenuto, Giuseppe; Basti, John J.; Levine, William N.

    2011-01-01

    Context: Total joint arthroplasty (TJA) is a common surgical option to treat painful degenerative joint disease. However, there is currently no consensus on the appropriate intensity of physical activity after TJA or how physical activity level affects the rate of revision surgery. Materials and Methods: A systematic review of the literature regarding physical or athletic activity after TJA was performed to determine current clinical opinion and recommendations regarding appropriate activity levels after TJA, as well as variables affecting successful surgery and improved outcomes. Results: Many studies in the literature regarding athletic activity after TJA focus on total hip arthroplasty and total knee arthroplasty. The literature reports contradictory results regarding rates of physical activity after TJA as well as the relationship between physical activity and rates of revision surgery. The current trend in expert opinion shows more liberal recommendations for patients to engage in athletic activity after TJA. Conclusions: Individual characteristics, lifestyle, and patient preferences must be taken into account when one considers appropriate recommendations for athletic activity after TJA. Current trends in clinical opinion favor a higher level of athletic activity after TJA, but clinicians should caution patients not to participate in contact sports or sports that create high joint loads in the replaced joint. PMID:23016041

  1. Dynamics of the human head-neck system in the horizontal plane: joint properties with respect to a static torque.

    PubMed

    Tangorra, James L; Jones, Lynette A; Hunter, Ian W

    2003-05-01

    The vestibular system has often been studied by perturbing the position of the head. This study was conducted to identify the dynamic properties of the head-neck system in response to horizontal plane perturbations. A quasilinear approach was used to quantify the dynamics of the head-neck system at different levels of static torque. An operating point was established by applying a static torque to the head with a helmet-based perturber. The head-neck dynamics were then probed with a rich spectrum, stochastic, torque perturbation. Impulse response functions (IRFs) were estimated from correlation measures, and parametric models were fit to the IRFs. The results indicated that when the mean torque was held constant, the head-neck system behaved like a second-order, underdamped, passive system between 0.5 and 10.0 Hz. The system was not strictly linear, however. The properties of the system were sensitive to the static component of the torque. As the mean torque increased, the effective stiffness and damping progressively increased, and did so such that the system's damping ratio remained essentially constant. The findings of the study will assist in designing stimuli that are well tolerated by subjects and can induce head motions that span the performance capabilities of the vestibular system. PMID:12757204

  2. Implementation of a physiologically identified PD feedback controller for regulating the active ankle torque during quiet stance.

    PubMed

    Vette, Albert H; Masani, Kei; Popovic, Milos R

    2007-06-01

    Our studies have recently demonstrated that a proportional and derivative (PD) feedback controller, which takes advantage of the body's position and velocity information to regulate balance during quiet standing, can compensate for long neurological time delays and generate a control command that precedes body sway by 100-200 ms. Furthermore, PD gain pairs were identified that ensure a robust system behavior and at the same time generate dynamic responses as observed in quiet standing experiments with able-bodied subjects. The purpose of the present study was to experimentally verify that the PD controller identified in our previous study can: 1) regulate the active ankle torque to stabilize the body during quiet standing in spite of long neurological time delays and 2) generate system dynamics, i.e., a motor command and body sway fluctuation, that successfully mimic those of the physiologic system of quiet standing. Our real-time closed-loop feedback circuit consisted of a center of mass position sensor and a functional electrical stimulator that elicited contractions of the plantar flexors as determined by the aforementioned PD controller. The control system regulated upright stance of a subject who was partially de-afferented and de-efferented due to a neurological disorder called von Hippel-Lindau Syndrome (McCormick Grade III). While the subject was able to generate a motor command for the ankle joints, he could not regulate the resulting torque sufficiently due to a lack of sensory feedback and motor control. It is important to mention that a time delay was included in the closed-loop circuit of the PD controller to mimic the actual neurological time delay observed in able-bodied individuals. The experimental results of this case study suggest that the proposed PD controller in combination with a functional electrical stimulation system can regulate the active ankle torque during quiet stance and generate the same system dynamics as observed in healthy

  3. Effect of Resistance Training Maintaining the Joint Angle-torque Profile Using a Haptic-based Machine on Shoulder Internal and External Rotation

    PubMed Central

    Kim, Yeonghun; Lee, Kunwoo; Moon, Jeheon; Koo, Dohoon; Park, Jaewoo; Kim, Kyengnam; Hong, Daehie; Shin, Inshik

    2014-01-01

    [Purpose] The aim of this study was to present an individualized resistance training method to enable exercise while maintaining an exercise load that is set according to an individual’s joint angle-torque using a haptic-based resistance training machine. [Methods] Five participants (machine group) performed individualized shoulder internal and external rotation training with a haptic resistance training machine, while another five participants performed general dumbbell-based shoulder internal and external rotation training for eight weeks. Internal and external rotation powers of subjects were measured using an isokinetic machine before and after training. [Results] The average powers of both shoulder internal and external rotation has been improved after training (25.72%, 13.62%). The improvement in power of external rotation in the machine group was significantly higher than that in the control group. [Conclusion] This study proposes a haptic-based individualized rotator cuff muscle training method. The training protocol maintaining the joint angle-torque profile showed better improvement of shoulder internal/external rotation than dumbbell training. PMID:24764626

  4. Quantifying anti-gravity torques for the design of a powered exoskeleton.

    PubMed

    Ragonesi, Daniel; Agrawal, Sunil K; Sample, Whitney; Rahman, Tariq

    2013-03-01

    Designing an upper extremity exoskeleton for people with arm weakness requires knowledge of the joint torques due to gravity and joint stiffness, as well as, active residual force capabilities of users. The objective of this research paper is to describe the characteristics of the upper limb of children with upper limb impairment. This paper describes the experimental measurements of the torque on the upper limb due to gravity and joint stiffness of three groups of subjects: able-bodied adults, able-bodied children, and children with neuromuscular disabilities. The experiment involves moving the arm to various positions in the sagittal plane and measuring the resultant force at the forearm. This force is then converted to torques at the elbow and shoulder. These data are compared to a two-link lumped mass model based on anthropomorphic data. Results show that the torques based on anthropometry deviate from experimentally measured torques as the arm goes through the range. Subjects with disabilities also maximally pushed and pulled against the force sensor to measure maximum strength as a function of arm orientation. For all subjects, the maximum voluntary applied torque at the shoulder and elbow in the sagittal plane was found to be lower than gravity torques throughout the disabled subjects' range of motion. This experiment informs designers of upper limb orthoses on the contribution of passive human joint torques due to gravity and joint stiffness and the strength capability of targeted users. PMID:23096118

  5. A Study of a Handrim-Activated Power-Assist Wheelchair Based on a Non-Contact Torque Sensor.

    PubMed

    Nam, Ki-Tae; Jang, Dae-Jin; Kim, Yong Chol; Heo, Yoon; Hong, Eung-Pyo

    2016-01-01

    Demand for wheelchairs is increasing with growing numbers of aged and disabled persons. Manual wheelchairs are the most commonly used assistive device for mobility because they are convenient to transport. Manual wheelchairs have several advantages but are not easy to use for the elderly or those who lack muscular strength. Therefore, handrim-activated power-assist wheelchairs (HAPAW) that can aid driving power with a motor by detecting user driving intentions through the handrim are being researched. This research will be on HAPAW that judge user driving intentions by using non-contact torque sensors. To deliver the desired motion, which is sensed from handrim rotation relative to a fixed controller, a new driving wheel mechanism is designed by applying a non-contact torque sensor, and corresponding torques are simulated. Torques are measured by a driving wheel prototype and compared with simulation results. The HAPAW prototype was developed using the wheels and a driving control algorithm that uses left and right input torques and time differences are used to check if the non-contact torque sensor can distinguish users' driving intentions. Through this procedure, it was confirmed that the proposed sensor can be used effectively in HAPAW. PMID:27509508

  6. The 2001 April Burst Activation of SGR 1900+14: Pulse Properties and Torque

    NASA Technical Reports Server (NTRS)

    Woods, P. M.; Kouveliotou, C.; Goegues, E.; Finger, M. H.; Feroci, M.; Mereghetti, S.; Swank, J. H.; Hurley, K.; Heise, J.; Smith, D.; Six, N. Frank (Technical Monitor)

    2002-01-01

    We report on observations of SGR 1900+14 made with the Rossi X-ray Timing Explorer (RXTE) and BeppoSAX during the April 2001 burst activation of the source. Using these data, we measure the spindown torque on the star and confirm earlier findings that the torque and burst activity are not directly correlated. We compare the X-ray pulse profile to the gamma-ray profile during the April 18 intermediate flare and show that (i) their shapes are similar and (ii) the gamma-ray profile aligns closely in phase with the X-ray pulsations. The good phase alignment of the gamma-ray and X-ray profiles suggests that there was no rapid spindown following this flare, in contrast to the August 27 giant flare. The absence of rapid spindown in the hours following the April 18 flare suggests that there was no significant outflow of material as was believed to be present following the August 27 flare. Finally, we discuss how these observations further constrain magnetic field reconfiguration models for the large flares of SGRs.

  7. A hybrid attitude controller consisting of electromagnetic torque rods and an active fluid ring

    NASA Astrophysics Data System (ADS)

    Nobari, Nona A.; Misra, Arun K.

    2014-01-01

    In this paper, a novel hybrid actuation system for satellite attitude stabilization is proposed along with its feasibility analysis. The system considered consists of two magnetic torque rods and one fluid ring to produce the control torque required in the direction in which magnetic torque rods cannot produce torque. A mathematical model of the system dynamics is derived first. Then a controller is developed to stabilize the attitude angles of a satellite equipped with the abovementioned set of actuators. The effect of failure of the fluid ring or a magnetic torque rod is examined as well. It is noted that the case of failure of the magnetic torque rod whose torque is along the pitch axis is the most critical, since the coupling between the roll or yaw motion and the pitch motion is quite weak. The simulation results show that the control system proposed is quite fault tolerant.

  8. Non-linear joint dynamics and controls of jointed flexible structures with active and viscoelastic joint actuators

    NASA Astrophysics Data System (ADS)

    Tzou, H. S.

    1990-12-01

    Studies on joint dominated flexible space structures have attracted much interest recently due to the rapid developments in large deployable space systems. This paper describes a study of the non-linear structural dynamics of jointed flexible structures with initial joint clearance and subjected to external excitations. Methods of using viscoelastic and active vibration control technologies, joint actuators, to reduce dynamic contact force and to stabilize the systems are proposed and evaluated. System dynamic equations of a discretized multi-degrees-of-freedom flexible system with initial joint clearances and joint actuators (active and viscoelastic passive) are derived. Dynamic contacts in an elastic joint are simulated by a non-linear joint model comprised of a non-linear spring and damper. A pseudo-force approximation method is used in numerical time-domain integration. Dynamic responses of a jointed flexible structure with and without viscoelastic and active joint actuators are presented and compared. Effectiveness of active/passive joint actuators is demonstrated.

  9. Hex ball torque test

    NASA Technical Reports Server (NTRS)

    Robinson, B. A.; Foster, C. L.

    1986-01-01

    A series of torque tests were performed on four flight-type hex ball universal joints in order to characterize and determine the actual load-carrying capability of this device. The universal joint is a part of manual actuation rods for scientific instruments within the Hubble Space Telescope. It was found that the hex ball will bind slightly during the initial load application. This binding did not affect the function of the universal joint, and the units would wear-in after a few additional loading cycles. The torsional yield load was approximately 50 ft-lb, and was consistent among the four test specimens. Also, the torque required to cause complete failure exceeded 80 ft-lb. It is concluded that the hex ball universal joint is suitable for its intended applications.

  10. Reduced elbow extension torque during vibrations.

    PubMed

    Friesenbichler, Bernd; Coza, Aurel; Nigg, Benno M

    2012-08-31

    Impact sports and vibration platforms trigger vibrations within soft tissues and the skeleton. Although the long-term effects of vibrations on the body have been studied extensively, the acute effects of vibrations are little understood. This study determined the influence of acute vibrations at different frequencies and elbow angles on maximal isometric elbow extension torque and muscle activity. Vibrations were generated by a pneumatic vibrator attached to the lever of a dynamometer, and were applied on the forearm of 15 healthy female subjects. The subjects were instructed to push maximally against the lever at three different elbow angles, while extension torque and muscle activity were quantified and compared between vibration and non-vibration (control) conditions. A change in vibration frequency had no significant effects on torque and muscle activity although vibrations in general decreased the maximal extension torque relative to the control by 1.8% (±5.7%, p>0.05), 7.4% (±7.9%, p<0.01), and 5.0% (±8.2%, p<0.01) at elbow angles of 60°, 90°, and 120°, respectively. Electromyographic activity increased significantly between ∼30% and 40% in both triceps and biceps with vibrations. It is speculated that a similar increase in muscle activity between agonist and antagonist, in combination with an unequal increase in muscle moment arms about the elbow joint, limit the maximal extension torque during exposure to vibrations. This study showed that maximal extension torque decreased during vibration exposure while muscle activity increased and suggests that vibrations may be counterproductive during activities requiring maximal strength but potentially beneficial for strength training. PMID:22771229

  11. The role of interaction torque and muscle torque in the control of downward squatting.

    PubMed

    Fujisawa, Hiroyuki; Suzuki, Hiroto; Murakami, Kenichi; Kawakami, Shingo; Suzuki, Makoto

    2016-01-01

    [Purpose] The purposes of this study were first to analyze the multijoint dynamics of downward squatting, and to examine the contribution of interaction torque and muscle torque to net torque, and second, to examine mechanisms of movement control. [Subjects] The subjects were 31 healthy men with a mean age of 21.0 ± 1.2 years (range, 19-24 years). [Methods] Squatting tasks with the trunk in two positions, an erect and anterior tilt position, were performed by the subjects. Net, interaction, muscle, and gravity torque were calculated according to the Lagrange equation using 3D tracking data. [Results] The contribution ratio of interaction torque to net torque was approximately 90%, irrespective of the joint and task. In contrast, muscle torque showed complicated behavior to compensate for gravity torque. A combined muscle and gravity torque profile showed flexion or dorsiflexion immediately after the initiation of the movement, and it later changed to extension or plantar flexion. [Conclusion] The torque that contributes almost exclusively to the net torque was interaction torque. The combination of muscle and gravity torque at the knee joint and the hip joint is important for movement control, independent of the starting position. PMID:27065552

  12. The role of interaction torque and muscle torque in the control of downward squatting

    PubMed Central

    Fujisawa, Hiroyuki; Suzuki, Hiroto; Murakami, Kenichi; Kawakami, Shingo; Suzuki, Makoto

    2016-01-01

    [Purpose] The purposes of this study were first to analyze the multijoint dynamics of downward squatting, and to examine the contribution of interaction torque and muscle torque to net torque, and second, to examine mechanisms of movement control. [Subjects] The subjects were 31 healthy men with a mean age of 21.0 ± 1.2 years (range, 19–24 years). [Methods] Squatting tasks with the trunk in two positions, an erect and anterior tilt position, were performed by the subjects. Net, interaction, muscle, and gravity torque were calculated according to the Lagrange equation using 3D tracking data. [Results] The contribution ratio of interaction torque to net torque was approximately 90%, irrespective of the joint and task. In contrast, muscle torque showed complicated behavior to compensate for gravity torque. A combined muscle and gravity torque profile showed flexion or dorsiflexion immediately after the initiation of the movement, and it later changed to extension or plantar flexion. [Conclusion] The torque that contributes almost exclusively to the net torque was interaction torque. The combination of muscle and gravity torque at the knee joint and the hip joint is important for movement control, independent of the starting position. PMID:27065552

  13. Application of Computational Lower Extremity Model to Investigate Different Muscle Activities and Joint Force Patterns in Knee Osteoarthritis Patients during Walking

    PubMed Central

    Nha, Kyung Wook; Shin, Jun Ho; Kim, Jong In; Kwon, Jae Ho; Kim, Yoon Hyuk

    2013-01-01

    Many experimental and computational studies have reported that osteoarthritis in the knee joint affects knee biomechanics, including joint kinematics, joint contact forces, and muscle activities, due to functional restriction and disability. In this study, differences in muscle activities and joint force patterns between knee osteoarthritis (OA) patients and normal subjects during walking were investigated using the inverse dynamic analysis with a lower extremity musculoskeletal model. Extensor/flexor muscle activations and torque ratios and the joint contact forces were compared between the OA and normal groups. The OA patients had higher extensor muscle forces and lateral component of the knee joint force than normal subjects as well as force and torque ratios of extensor and flexor muscles, while the other parameters had little differences. The results explained that OA patients increased the level of antagonistic cocontraction and the adduction moment on the knee joint. The presented findings and technologies provide insight into biomechanical changes in OA patients and can also be used to evaluate the postoperative functional outcomes of the OA treatments. PMID:24302973

  14. Evaluation of force-torque displays for use with space station telerobotic activities

    NASA Technical Reports Server (NTRS)

    Hendrich, Robert C.; Bierschwale, John M.; Manahan, Meera K.; Stuart, Mark A.; Legendre, A. Jay

    1992-01-01

    Recent experiments which addressed Space Station remote manipulation tasks found that tactile force feedback (reflecting forces and torques encountered at the end-effector through the manipulator hand controller) does not improve performance significantly. Subjective response from astronaut and non-astronaut test subjects indicated that force information, provided visually, could be useful. No research exists which specifically investigates methods of presenting force-torque information visually. This experiment was designed to evaluate seven different visual force-torque displays which were found in an informal telephone survey. The displays were prototyped in the HyperCard programming environment. In a within-subjects experiment, 14 subjects nullified forces and torques presented statically, using response buttons located at the bottom of the screen. Dependent measures included questionnaire data, errors, and response time. Subjective data generally demonstrate that subjects rated variations of pseudo-perspective displays consistently better than bar graph and digital displays. Subjects commented that the bar graph and digital displays could be used, but were not compatible with using hand controllers. Quantitative data show similar trends to the subjective data, except that the bar graph and digital displays both provided good performance, perhaps do to the mapping of response buttons to display elements. Results indicate that for this set of displays, the pseudo-perspective displays generally represent a more intuitive format for presenting force-torque information.

  15. Targeted brain activation using an MR-compatible wrist torque measurement device and isometric motor tasks during functional magnetic resonance imaging.

    PubMed

    Vlaar, Martijn P; Mugge, Winfred; Groot, Paul F C; Sharifi, Sarvi; Bour, Lo J; van der Helm, Frans C T; van Rootselaar, Anne-Fleur; Schouten, Alfred C

    2016-07-01

    Dedicated pairs of isometric wrist flexion tasks, with and without visual feedback of the exerted torque, were designed to target activation of the CBL and BG in healthy subjects during functional magnetic resonance imaging (fMRI). Selective activation of the cerebellum (CBL) and basal ganglia (BG), often implicated in movement disorders such as tremor and dystonia, may help identify pathological changes and expedite diagnosis. A prototyped MR-compatible wrist torque measurement device, free of magnetic and conductive materials, allowed safe execution of tasks during fMRI without causing artifacts. A significant increase of activity in CBL and BG was found in healthy volunteers during a constant torque task with visual feedback compared to a constant torque task without visual feedback. This study shows that specific pairs of motor tasks using MR-compatible equipment at the wrist allow for targeted activation of CBL and BG, paving a new way for research into the pathophysiology of movement disorders. PMID:26968144

  16. Activity Levels in Healthy Older Adults: Implications for Joint Arthroplasty

    PubMed Central

    Thorp, Laura E.; Orozco, Diego; Block, Joel A.; Sumner, Dale R.; Wimmer, Markus A.

    2012-01-01

    This work evaluated activity levels in a group of healthy older adults to establish a target activity level for adults of similar age after total joint arthroplasty (TJA). With the decreasing age of TJA patients, it is essential to have a reference for activity level in younger patients as activity level affects quality of life and implant design. 54 asymptomatic, healthy older adults with no clinical evidence of lower extremity OA participated. The main outcome measure, average daily step count, was measured using an accelerometer-based activity monitor. On average the group took 8813 ± 3611 steps per day, approximately 4000 more steps per day than has been previously reported in patients following total joint arthroplasty. The present work provides a reference for activity after joint arthroplasty which is relevant given the projected number of people under the age of 65 who will undergo joint arthroplasty in the coming years. PMID:23577274

  17. Optical imaging of the prefrontal activity in joint attention experience

    PubMed Central

    Qiu, Lina; Zhang, Xiao; Li, Jun

    2015-01-01

    Functional near-infrared spectroscopy (fNIRS) was used to measure the prefrontal activity in joint attention experience. 16 healthy adults participated in the experiment in which 42 optical channels were fixed over the anterior prefrontal cortex (aPFC), dorsolateral prefrontal cortex (DLPFC), inferior frontal gyrus (IFG) and a small anterior portion of the superior temporal gyrus (STG). Video stimuli were used to engender joint or non-joint attention experience in observers. Cortical hemodynamic response and functional connectivity were measured and averaged across all subjects for each stimulus condition. Our data showed the activation in joint attention located in the aPFC and DLPFC bilaterally, but dominantly in the left hemisphere. This observation, together with the previous findings on infants and children, provides a clear developmental scenario on the prefrontal activation associated with joint attention process. In the case of non-joint attention condition, only a small region of the right DLPFC was activated. Functional connectivity was observed to be enhanced, but differently in joint and non-joint attention condition. PMID:26417513

  18. Muscle Torque and its Relation to Technique, Tactics, Sports Level and Age Group in Judo Contestants

    PubMed Central

    Lech, Grzegorz; Chwała, Wiesław; Ambroży, Tadeusz; Sterkowicz, Stanisław

    2015-01-01

    The aim of this study was to perform a comparative analysis of maximal muscle torques at individual stages of development of athletes and to determine the relationship between muscle torques, fighting methods and the level of sports performance. The activity of 25 judo contestants during judo combats and the effectiveness of actions were evaluated. Maximum muscle torques in flexors/extensors of the body trunk, shoulder, elbow, hip and knee joints were measured. The level of significance was set at p≤0.05; for multiple comparisons the Mann-Whitney U test, p≤0.016, was used. Intergroup differences in relative torques in five muscle groups studied (elbow extensors, shoulder flexors, knee flexors, knee extensors, hip flexors) were not significant. In cadets, relative maximum muscle torques in hip extensors correlated with the activity index (Spearman’s r=0.756). In juniors, maximum relative torques in elbow flexors and knee flexors correlated with the activity index (r=0.73 and r=0.76, respectively). The effectiveness of actions correlated with relative maximum torque in elbow extensors (r=0.67). In seniors, the relative maximum muscle torque in shoulder flexors correlated with the activity index during the second part of the combat (r=0.821). PMID:25964820

  19. Quantifying anti-gravity torques in the design of a powered exoskeleton.

    PubMed

    Ragonesi, Daniel; Agrawal, Sunil; Sample, Whitney; Rahman, Tariq

    2011-01-01

    Designing an upper extremity exoskeleton for people with arm weakness requires knowledge of the passive and active residual force capabilities of users. This paper experimentally measures the passive gravitational torques of 3 groups of subjects: able-bodied adults, able bodied children, and children with neurological disabilities. The experiment involves moving the arm to various positions in the sagittal plane and measuring the gravitational force at the wrist. This force is then converted to static gravitational torques at the elbow and shoulder. Data are compared between look-up table data based on anthropometry and empirical data. Results show that the look-up torques deviate from experimentally measured torques as the arm reaches up and down. This experiment informs designers of Upper Limb orthoses on the contribution of passive human joint torques. PMID:22256063

  20. Evoked electromyography-based closed-loop torque control in functional electrical stimulation.

    PubMed

    Zhang, Qin; Hayashibe, Mitsuhiro; Azevedo-Coste, Christine

    2013-08-01

    This paper proposed a closed-loop torque control strategy of functional electrical stimulation (FES) with the aim of obtaining an accurate, safe, and robust FES system. Generally, FES control systems are faced with the challenge of how to deal with time-variant muscle dynamics due to physiological and biochemical factors (such as fatigue). The degraded muscle force needs to be compensated in order to ensure the accuracy of the motion restored by FES. Another challenge concerns the fact that implantable sensors are unavailable to feedback torque information for FES in humans. As FES-evoked electromyography (EMG) represents the activity of stimulated muscles, and also enables joint torque prediction as presented in our previous studies, here we propose an EMG-feedback predictive controller of FES to control joint torque adaptively. EMG feedback contributes to taking the activated muscle state in the FES torque control system into account. The nature of the predictive controller facilitates prediction of the muscle mechanical response and the system can therefore control joint torque from EMG feedback and also respond to time-variant muscle state changes. The control performance, fatigue compensation and aggressive control suppression capabilities of the proposed controller were evaluated and discussed through experimental and simulation studies. PMID:23529189

  1. Elbow torques and EMG patterns of flexor muscles during different isometric tasks.

    PubMed

    Caldwell, G E; Van Leemputte, M

    1991-01-01

    This paper examines the torque responses and EMG activity levels in four muscles acting at the elbow joint during different combinations of one- and two- degree of freedom isometric torque production (single and dual tasks, respectively). Flexor and supinator/pronator torques and surface EMG signals from m. biceps brachii, m. brachialis, m. brachioradialis and m. triceps brachii were measured in 16 male subjects while they performed maximal effort isometric contractions of pure flexion, pure supination, pure pronation, combined flexion and supination and combined flexion and pronation. In the single tasks, the torque responses were consistent with task requirements, but the dual task results were surprising in that flexor torque levels were reduced as compared to pure flexion, while supinator/pronator torque levels were as high or higher than in pure supination or pronation. Muscle activity levels varied with task, and could not always explain the differences observed in torque responses. These data are discussed within the framework of subpopulations of task-specific motor units within each muscle. The implications of such task-specific muscle units are related to musculoskeletal modelling and previous EMG - torque relationships found at the elbow. PMID:1748080

  2. High torque bellows seal rotary drive

    NASA Technical Reports Server (NTRS)

    Diaguila, A. J.; Macomber, J. W.; Adams, D. W.

    1972-01-01

    Bellows seal rotary drive device was developed which allows high torque transmission through sealed compartments. Bearing friction which would normally be carried by sealing bellows in comparable devices is absorbed by universal-gimbal joint. It can be used to transmit high torque, low speed, rotary motion through sealed barriers to prevent contamination or escape of fluids.

  3. Spinal circuits can accommodate interaction torques during multijoint limb movements

    PubMed Central

    Buhrmann, Thomas; Di Paolo, Ezequiel A.

    2014-01-01

    The dynamic interaction of limb segments during movements that involve multiple joints creates torques in one joint due to motion about another. Evidence shows that such interaction torques are taken into account during the planning or control of movement in humans. Two alternative hypotheses could explain the compensation of these dynamic torques. One involves the use of internal models to centrally compute predicted interaction torques and their explicit compensation through anticipatory adjustment of descending motor commands. The alternative, based on the equilibrium-point hypothesis, claims that descending signals can be simple and related to the desired movement kinematics only, while spinal feedback mechanisms are responsible for the appropriate creation and coordination of dynamic muscle forces. Partial supporting evidence exists in each case. However, until now no model has explicitly shown, in the case of the second hypothesis, whether peripheral feedback is really sufficient on its own for coordinating the motion of several joints while at the same time accommodating intersegmental interaction torques. Here we propose a minimal computational model to examine this question. Using a biomechanics simulation of a two-joint arm controlled by spinal neural circuitry, we show for the first time that it is indeed possible for the neuromusculoskeletal system to transform simple descending control signals into muscle activation patterns that accommodate interaction forces depending on their direction and magnitude. This is achieved without the aid of any central predictive signal. Even though the model makes various simplifications and abstractions compared to the complexities involved in the control of human arm movements, the finding lends plausibility to the hypothesis that some multijoint movements can in principle be controlled even in the absence of internal models of intersegmental dynamics or learned compensatory motor signals. PMID:25426061

  4. Diffuse optical imaging of brain activation to joint attention experience.

    PubMed

    Zhu, Banghe; Yadav, Nitin; Rey, Gustavo; Godavarty, Anuradha

    2009-08-24

    In the early development of social cognition and language, infants tend to participate in face-to-face interactions engaging in joint attention exchanges. Joint attention is vital to social competence at all ages, lacking which is a primary feature to distinguish autistic from non-autistic population. In this study, diffuse optical imaging is used for the first time to investigate the joint attention experience in normal adults. Imaging studies were performed in the frontal regions of the brain (BA9 and BA10) in order to study the differences in the brain activation in response to video clips corresponding to joint attention based skills. The frontal regions of the brain were non-invasively imaged using a novel optical cap coupled to a frequency-domain optical imaging system. The statistical analysis from 11 normal adult subjects, with three repetitions from each subject, indicated that the averaged changes in the cerebral blood oxygenation levels were different under the joint and non-joint attention based stimulus. The preliminary studies demonstrate the feasibility of implementing diffuse optical imaging towards autism-related research to study the brain activation in response to socio-communication skills. PMID:19447278

  5. Characterization of the torque limits and clamping force relationships for small stainless steel screws in tensile loaded joints of various metals

    SciTech Connect

    Bernardin, John D; Flores, Eugene M

    2009-01-01

    This study originated during the design of ChemCam, a Laser Induced Breakdown Spectroscopy (LIBS) and imaging instrument being developed for NASA's Mars Science Lab Rover. The mission needs for miniaturization, reduced weight, high reliability, minimal use of thread locking compounds, and the ability to handle harsh environmental conditions dictated the use of small, high strength screws to be threaded into a variety of metal alloys including Be-S200f, Al-6061-T6, Mg-ZK60A-T5, and Ti-6Al-4V The lack of a credible fastener torque database for small (No.0 through No.8) high strength stainless steel screws in various parent materials, led to the development of an experimental program to characterize the following: (A) The screw torque value versus angular rotation (which indicates yielding in the screw or parent material) as a function of screw diameter, screw head configuration, depth of thread engagement, type of parent material, type of surface treatment on parent material, presence of thread locking compound, repeatable threaded hole use, and degree of screw pedigree. (B) The relationship between fastener torque and clamping force for a subset of the above mentioned variables. The database generated from this study will serve as a design reference for utilizing small stainless steel fasteners and provide trending information for other researchers who may be interested in broadening its range of parameters. This paper reviews the related fastener torque and clamping force information from the literature, describes the experimental screw torque and clamping force monitoring equipment, presents the test matrix and experimental procedures, and discusses the empirical results.

  6. Modifications in ankle dorsiflexor activation by applying a torque perturbation during walking in persons post-stroke: a case series

    PubMed Central

    2014-01-01

    Background Results obtained in a previous study (Gait Posture 34:358–363, 2011) have shown that, in non-disabled participants, a specific increase in ankle dorsiflexor (Tibialis anterior [TA]) activation can be induced by walking with a torque perturbation that plantarflexes the ankle during the swing phase. After perturbation removal, the increased TA activation persisted temporarily and was associated with a more dorsiflexed ankle during swing. The objective of the present case-series study was to verify if these results can be reproduced in persons post-stroke. Methods Six participants who sustained a stroke walked on a treadmill before, during and after exposure to a torque perturbation applied at the ankle by a robotized ankle-foot orthosis. Spatiotemporal gait parameters, ankle and knee kinematics, and the electromyographic activity of TA and Soleus were recorded. Mean amplitude of the TA burst located around toe off and peak ankle dorsiflexion angle during swing were compared across the 3 walking periods for each participant. Results At the end of the walking period with the perturbation, TA mean amplitude was significantly increased in 4 of the 6 participants. Among these 4 participants, modifications in TA activation persisted after perturbation removal in 3 of them, and led to a statistically significant increase in peak dorsiflexion during swing. Clinical implications This approach may be helpful to evaluate the residual adaptive capacity in the ankle dorsiflexors after a stroke and guide decision-making for the selection of optimal rehabilitation interventions. Future work will investigate the clinical impact of a multiple-session gait training based on this approach in persons presenting a reduced ankle dorsiflexion during the swing phase of walking. PMID:24912626

  7. Shoulder model validation and joint contact forces during wheelchair activities

    PubMed Central

    Morrow, Melissa M.B.; Kaufman, Kenton R.; An, Kai-Nan

    2010-01-01

    Chronic shoulder impingement is a common problem for manual wheelchair users. The loading associated with performing manual wheelchair activities of daily living is substantial and often at a high frequency. Musculoskeletal modeling and optimization techniques can be used to estimate the joint contact forces occurring at the shoulder to assess the soft tissue loading during an activity and to possibly identify activities and strategies that place manual wheelchair users at risk for shoulder injuries. The purpose of this study was to validate an upper extremity musculoskeletal model and apply the model to wheelchair activities for analysis of the estimated joint contact forces. Upper extremity kinematics and handrim wheelchair kinetics were measured over three conditions: level propulsion, ramp propulsion, and a weight relief lift. The experimental data were used as input to a subject-specific musculoskeletal model utilizing optimization to predict joint contact forces of the shoulder during all conditions. The model was validated using a mean absolute error calculation. Model results confirmed that ramp propulsion and weight relief lifts place the shoulder under significantly higher joint contact loading than level propulsion. In addition, they exhibit large superior contact forces that could contribute to impingement. This study highlights the potential impingement risk associated with both the ramp and weight relief lift activities. Level propulsion was shown to have a low relative risk of causing injury, but with consideration of the frequency with which propulsion is performed, this observation is not conclusive. PMID:20840833

  8. Improved computed torque control for industrial robots

    NASA Technical Reports Server (NTRS)

    Uebel, Mark; Minis, Ioannis; Cleary, Kevin

    1992-01-01

    The authors examine the computed torque control problem for a robot arm with flexible, geared, joint drive systems which are typical in many industrial robots. The standard computed torque algorithm is not directly applicable to this class of manipulators due to the dynamics introduced by the joint drive systems. The proposed approach overcomes this problem by combining a novel computed torque algorithm with simple torque controllers at each joint of the robot. The control scheme is applied to a seven degree-of-freedom industrial manipulator, and the system performance in standard tasks is evaluated using both dynamic simulation and actual experiments. The results show that the proposed controller leads to improved tracking performance over a conventional PD (proportional plus derivative) controller.

  9. Spacesuit mobility knee joints

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C. (Inventor)

    1979-01-01

    Pressure suit mobility joints are for use in interconnecting adjacent segments of an hermetically sealed spacesuit in which low torques, low leakage and a high degree of reliability are required. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics and includes linkages which restrain the joint from longitudinal distension and includes a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

  10. Spacesuit mobility joints

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C. (Inventor)

    1978-01-01

    Joints for use in interconnecting adjacent segments of an hermetically sealed spacesuit which have low torques, low leakage and a high degree of reliability are described. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics. Linkages which restrain the joint from longitudinal distension and a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli are featured. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

  11. DOD-DOE Workshop on Joint Energy Activities

    SciTech Connect

    1980-01-01

    The general conditions for DOD-DOE interactions were delineated in an October 1978, Memorandum of Understanding (MOU) that identified two basic goals: improving energy efficiency and availability within DOD, and utilizing DOD and DOE expertise and facilities to carry out projects of mutual interest. There has been considerable interaction between DOD and DOE, including a number of proposed joint initiatives but a systematic and coordinated approach for nurturing, maintaining, and expanding these relationships has not been developed. A DOD-DOE Workshop on Joint Energy Activities was held on March 10-12, 1980. The workshop was structured into five working groups - Mobility Fuels, Conservation, Fossil Fuels for Fixed Facilities, Solar and Renewable Energy Sources, and Special Projects - with DOD and DOE cochairmen for each. Over a hundred DOD and DOE management, program, and policymaking representatives were brought together by the workshop Steering Committee to identify specific programs for inclusion in an overall plan for implementing the MOU and to deal with fundamental issues and problems of maintaining future communications. The workshop accomplished its goals, these being to: (1) improve communication among the appropriate key DOD and DOE personnel at all levels and promote information exchange; (2) review ongoing and already-proposed joint DOD and DOE programs; (3) initiate a coordinated, systematic effort to establish joint DOD-DOE energy-security programs; and (4) propose specific programs and projects of mutual interest for inclusion in a follow-on joint-implementation plan.

  12. Active Design Method for the Static Characteristics of a Piezoelectric Six-Axis Force/Torque Sensor

    PubMed Central

    Liu, Jun; Li, Min; Qin, Lan; Liu, Jingcheng

    2014-01-01

    To address the bottleneck issues of an elastic-style six-axis force/torque sensor (six-axis force sensor), this work proposes a no-elastic piezoelectric six-axis force sensor. The operating principle of the piezoelectric six-axis force sensor is analyzed, and a structural model is constructed. The static-active design theory of the piezoelectric six-axis force sensor is established, including a static analytical/mathematical model and numerical simulation model (finite element model). A piezoelectric six-axis force sensor experimental prototype is developed according to the analytical mathematical model and numerical simulation model, and selected static characteristic parameters (including sensitivity, isotropic degree and cross-coupling) are tested using this model with three approaches. The measured results are in agreement with the analytical results from the static-active design method. Therefore, this study has successfully established a foundation for further research into the piezoelectric multi-axis force sensor and an overall design approach based on static characteristics. PMID:24451460

  13. Active design method for the static characteristics of a piezoelectric six-axis force/torque sensor.

    PubMed

    Liu, Jun; Li, Min; Qin, Lan; Liu, Jingcheng

    2014-01-01

    To address the bottleneck issues of an elastic-style six-axis force/torque sensor (six-axis force sensor), this work proposes a no-elastic piezoelectric six-axis force sensor. The operating principle of the piezoelectric six-axis force sensor is analyzed, and a structural model is constructed. The static-active design theory of the piezoelectric six-axis force sensor is established, including a static analytical/mathematical model and numerical simulation model (finite element model). A piezoelectric six-axis force sensor experimental prototype is developed according to the analytical mathematical model and numerical simulation model, and selected static characteristic parameters (including sensitivity, isotropic degree and cross-coupling) are tested using this model with three approaches. The measured results are in agreement with the analytical results from the static-active design method. Therefore, this study has successfully established a foundation for further research into the piezoelectric multi-axis force sensor and an overall design approach based on static characteristics. PMID:24451460

  14. Torque resolver design for tendon-driven manipulators

    SciTech Connect

    Lee, J.J.; Tsai, Lung-Wen

    1992-08-01

    Given a set of desired joint torques in an n-DOF tendon-driven manipulator with n + 1 control tendons, the determination of tendon forces is an indeterminate problem. Usually, the pseudo-inverse technique is used to solve for such a problem. In this paper, rather than using the pseudo-inverse technique is used to solve for such a problem. In this paper, rather than using the pseudo-inverse technique, an efficient methodology for transforming joint torques (n elements) to motor torques (n + 1 elements) has been developed. This technique called ``torque resolver``, utilizes two circuit-like operators to transform torques between the two different vector spaces. It can be easily programmed on a digital computer or implemented into an analog-circuit system. It is hoped that this technique will make real-time computed-torque control feasible. The technique has been demonstrated through the dynamic simulation of a three-DOF manipulator.

  15. Torque resolver design for tendon-driven manipulators

    SciTech Connect

    Lee, J.J.; Tsai, Lung-Wen.

    1992-01-01

    Given a set of desired joint torques in an n-DOF tendon-driven manipulator with n + 1 control tendons, the determination of tendon forces is an indeterminate problem. Usually, the pseudo-inverse technique is used to solve for such a problem. In this paper, rather than using the pseudo-inverse technique is used to solve for such a problem. In this paper, rather than using the pseudo-inverse technique, an efficient methodology for transforming joint torques (n elements) to motor torques (n + 1 elements) has been developed. This technique called torque resolver'', utilizes two circuit-like operators to transform torques between the two different vector spaces. It can be easily programmed on a digital computer or implemented into an analog-circuit system. It is hoped that this technique will make real-time computed-torque control feasible. The technique has been demonstrated through the dynamic simulation of a three-DOF manipulator.

  16. Torque patterns of the limbs of small therian mammals during locomotion on flat ground.

    PubMed

    Witte, Hartmut; Biltzinger, Jutta; Hackert, Rémi; Schilling, Nadja; Schmidt, Manuela; Reich, Christian; Fischer, Martin S

    2002-05-01

    In three species of small therian mammals (Scandentia: Tupaia glis, Rodentia: Galea musteloides and Lagomorpha: Ochotona rufescens) the net joint forces and torques acting during stance phase in the four kinematically relevant joints of the forelimbs (scapular pivot, shoulder joint, elbow joint, wrist joint) and the hindlimbs (hip joint, knee joint, ankle joint, intratarsal joint) were determined by inverse dynamic analysis. Kinematics were measured by cineradiography (150 frames s(-1)). Synchronously ground reaction forces were acquired by forceplates. Morphometry of the extremities was performed by a scanning method using structured illumination. The vector sum of ground reaction forces and weight accounts for most of the joint force vector. Inertial effects can be neglected since errors of net joint forces amount at most to 10 %. The general time course of joint torques is comparable for all species in all joints of the forelimb and in the ankle joint. Torques in the intratarsal joints differ between tailed and tail-less species. The torque patterns in the knee and hip joint are unique to each species. For the first time torque patterns are described completely for the forelimb including the scapula as the dominant propulsive segment. The results are compared with the few torque data available for various joints of cats (Felis catus), dogs (Canis lupus f. familiaris), goats (Capra sp.) and horses (Equus przewalskii f. caballus). PMID:11948209

  17. Shoulder Joint For Protective Suit

    NASA Technical Reports Server (NTRS)

    Kosmo, Joseph J.; Smallcombe, Richard D.

    1994-01-01

    Shoulder joint allows full range of natural motion: wearer senses little or no resisting force or torque. Developed for space suit, joint offers advantages in protective garments for underwater work, firefighting, or cleanup of hazardous materials.

  18. Human ankle joint stiffness over the full range of muscle activation levels.

    PubMed

    Weiss, P L; Hunter, I W; Kearney, R E

    1988-01-01

    System identification techniques have been used to track changes in dynamic stiffness of the human ankle joint over a wide range of muscle contraction levels. Subjects lay supine on an experimental table with their left foot encased in a rigid, low-inertia cast which was fixed to an electro-hydraulic actuator operating as a position servo. Subjects generated tonic plantarflexor or dorsiflexor torques of different magnitudes ranging from rest to maximum voluntary contractions (MVC) during repeated presentations of a stochastic ankle angular position perturbation. Compliance impulse response functions (IRF) were determined from every 2.5 s perturbation sequence. The gain (G), natural frequency (omega n), and damping (zeta) parameters of the second-order model providing the best fit to each IRF were determined and used to compute the corresponding inertial (I), viscous (B) and elastic (K) stiffness parameters. The behaviour of these parameters with mean torque was found to follow two simple rules. First, the elastic parameter (K) increased in proportion to mean ankle torque as it was varied from rest to MVC; these changes were considerable involving increases of more than an order of magnitude. Second, the damping parameter (zeta) remained almost invariant over the entire range of contractions despite the dramatic changes in K. PMID:3410857

  19. Spin-torque building blocks.

    PubMed

    Locatelli, N; Cros, V; Grollier, J

    2014-01-01

    The discovery of the spin-torque effect has made magnetic nanodevices realistic candidates for active elements of memory devices and applications. Magnetoresistive effects allow the read-out of increasingly small magnetic bits, and the spin torque provides an efficient tool to manipulate - precisely, rapidly and at low energy cost - the magnetic state, which is in turn the central information medium of spintronic devices. By keeping the same magnetic stack, but by tuning a device's shape and bias conditions, the spin torque can be engineered to build a variety of advanced magnetic nanodevices. Here we show that by assembling these nanodevices as building blocks with different functionalities, novel types of computing architecture can be envisaged. We focus in particular on recent concepts such as magnonics and spintronic neural networks. PMID:24343514

  20. Spin-torque building blocks

    NASA Astrophysics Data System (ADS)

    Locatelli, N.; Cros, V.; Grollier, J.

    2014-01-01

    The discovery of the spin-torque effect has made magnetic nanodevices realistic candidates for active elements of memory devices and applications. Magnetoresistive effects allow the read-out of increasingly small magnetic bits, and the spin torque provides an efficient tool to manipulate -- precisely, rapidly and at low energy cost -- the magnetic state, which is in turn the central information medium of spintronic devices. By keeping the same magnetic stack, but by tuning a device's shape and bias conditions, the spin torque can be engineered to build a variety of advanced magnetic nanodevices. Here we show that by assembling these nanodevices as building blocks with different functionalities, novel types of computing architecture can be envisaged. We focus in particular on recent concepts such as magnonics and spintronic neural networks.

  1. Effect of Preactivation on Torque Enhancement by the Stretch-Shortening Cycle in Knee Extensors

    PubMed Central

    Fukutani, Atsuki; Misaki, Jun; Isaka, Tadao

    2016-01-01

    The stretch-shortening cycle is one of the most interesting topics in the field of sport sciences, because the performance of human movement is enhanced by the stretch-shortening cycle (eccentric contraction). The purpose of the present study was to examine whether the influence of preactivation on the torque enhancement by stretch-shortening cycle in knee extensors. Twelve men participated in this study. The following three conditions were conducted for knee extensors: (1) concentric contraction without preactivation (CON), (2) concentric contraction with eccentric preactivation (ECC), and (3) concentric contraction with isometric preactivation (ISO). Muscle contractions were evoked by electrical stimulation to discard the influence of neural activity. The range of motion of the knee joint was set from 80 to 140 degrees (full extension = 180 degrees). Angular velocities of the concentric and eccentric contractions were set at 180 and 90 degrees/s, respectively. In the concentric contraction phase, joint torques were recorded at 85, 95, and 105 degrees, and they were compared among the three conditions. In the early phase (85 degrees) of concentric contraction, the joint torque was larger in the ECC and ISO conditions than in the CON condition. However, these clear differences disappeared in the later phase (105 degrees) of concentric contraction. The results showed that joint torque was clearly different among the three conditions in the early phase whereas this difference disappeared in the later phase. Thus, preactivation, which is prominent in the early phase of contractions, plays an important role in torque enhancement by the stretch-shortening cycle in knee extensors. PMID:27414804

  2. Torque Limits for Fasteners in Composites

    NASA Technical Reports Server (NTRS)

    Zhao, Yi

    2002-01-01

    The two major classes of laminate joints are bonded and bolted. Often the two classes are combined as bonded-bolted joints. Several characteristics of fiber reinforced composite materials render them more susceptible to joint problems than conventional metals. These characteristics include weakness in in-plane shear, transverse tension/compression, interlaminar shear, and bearing strength relative to the strength and stiffness in the fiber direction. Studies on bolted joints of composite materials have been focused on joining assembly subject to in-plane loads. Modes of failure under these loading conditions are net-tension failure, cleavage tension failure, shear-out failure, bearing failure, etc. Although the studies of torque load can be found in literature, they mainly discussed the effect of the torque load on in-plane strength. Existing methods for calculating torque limit for a mechanical fastener do not consider connecting members. The concern that a composite member could be crushed by a preload inspired the initiation of this study. The purpose is to develop a fundamental knowledge base on how to determine a torque limit when a composite member is taken into account. Two simplified analytical models were used: a stress failure analysis model based on maximum stress criterion, and a strain failure analysis model based on maximum strain criterion.

  3. Elbow Joint Active Replication in College Pitchers Following Simulated Game Throwing

    PubMed Central

    Manske, Robert; Stovak, Mark; Cox, Kara; Smith, Barbara

    2010-01-01

    Background: Elbow injuries are common in college baseball players. Pitching creates stress and fatigue in and around the elbow. Lack of joint proprioception can contribute to nonphysiological joint loading and injury. Hypothesis: There will be no difference in elbow joint active reproduction sense following a simulated 3-inning pitching sequence. Study Design: Cross-sectional study. Methods: Seventeen collegiate pitchers participated. Each pitcher was bilaterally tested for active elbow range of motion using goniometric technique. Percentages of motion determined positions for further study of elbow joint active replication sense (20%, 35%, 50%, 80%). The elbow was passively taken to a position and held for 10 seconds, then returned to full extension. Pitchers were asked to actively reproduce the angle. The opposite elbow was tested in the same manner. One week later, prethrowing joint position reproduction was tested; then a simulated 3-inning game was thrown. Immediately afterward, elbow joint active replication testing was performed. A repeated-measures analysis of variance analyzed differences. Results: No change in active joint reproduction occurred in the nondominant elbow at any angle tested. Dominant elbows demonstrated significant losses of active joint reproduction following throwing. Significant differences occurred at the 35% and 80% angles (P < .05). Conclusion: Active elbow joint replication sense may be compromised following 3 innings of throwing. Because joint proprioception is thought to be an important component of joint stabilization, an alteration in joint position sense may increase the risk of elbow injury during throwing. Clinical Relevance: Pitching may cause a loss of active elbow joint replication. PMID:23015958

  4. Methodology for Determining Limit Torques for Threaded Fasteners

    NASA Technical Reports Server (NTRS)

    Hissam, Andy

    2011-01-01

    In aerospace design, where minimizing weight is always a priority, achieving the full capacity from fasteners is essential. To do so, the initial bolt preload must be maximized. The benefits of high preload are well documented and include improved fatigue resistance, a stiffer joint, and resistance to loosening. But many factors like elastic interactions and embedment tend to lower the initial preload placed on the bolt. These factors provide additional motivation to maximize the initial preload. But, to maximize bolt preload, you must determine what torque to apply. Determining this torque is greatly complicated by the large preload scatter generally seen with torque control. This paper presents a detailed methodology for generating limit torques for threaded fasteners. This methodology accounts for the large scatter in preload found with torque control, and therefore, addresses the statistical nature of the problem. It also addresses prevailing torque, a feature common in aerospace fasteners. Although prevailing torque provides a desired locking feature, it can also increase preload scatter. In addition, it can limit the amount of preload that can be generated due to the torsion it creates in the bolt. This paper discusses the complications of prevailing torque and how best to handle it. A wide range of torque-tension bolt testing was conducted in support of this research. The results from this research will benefit the design engineer as well as analyst involved in the design of bolted joints, leading to better, more optimized structural designs.

  5. Passive Joint Forces Are Tuned to Limb Use in Insects and Drive Movements without Motor Activity

    PubMed Central

    Ache, Jan M.; Matheson, Thomas

    2013-01-01

    Summary Background Limb movements are generally driven by active muscular contractions working with and against passive forces arising in muscles and other structures. In relatively heavy limbs, the effects of gravity and inertia predominate, whereas in lighter limbs, passive forces intrinsic to the limb are of greater consequence. The roles of passive forces generated by muscles and tendons are well understood, but there has been little recognition that forces originating within joints themselves may also be important, and less still that these joint forces may be adapted through evolution to complement active muscle forces acting at the same joint. Results We examined the roles of passive joint forces in insect legs with different arrangements of antagonist muscles. We first show that passive forces modify actively generated movements of a joint across its working range, and that they can be sufficiently strong to generate completely passive movements that are faster than active movements observed in natural behaviors. We further demonstrate that some of these forces originate within the joint itself. In legs of different species adapted to different uses (walking, jumping), these passive joint forces complement the balance of strength of the antagonist muscles acting on the joint. We show that passive joint forces are stronger where they assist the weaker of two antagonist muscles. Conclusions In limbs where the dictates of a key behavior produce asymmetry in muscle forces, passive joint forces can be coadapted to provide the balance needed for the effective generation of other behaviors. PMID:23871240

  6. Social-Cultural-Historical Contradictions in an L2 Listening Lesson: A Joint Activity System Analysis

    ERIC Educational Resources Information Center

    Cross, Jeremy

    2011-01-01

    Informed and inspired by neo-Vygotskian theory, this article outlines a study exploiting a contemporary conceptualization of Wells's (2002) joint activity system model as an exploratory framework for examining and depicting the social-cultural-historical contradictions in second-language (L2) learners' joint activity. The participants were a pair…

  7. Angular Acceleration Without Torque?

    NASA Astrophysics Data System (ADS)

    Kaufman, Richard D.

    2012-01-01

    Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.2

  8. Angular Acceleration without Torque?

    ERIC Educational Resources Information Center

    Kaufman, Richard D.

    2012-01-01

    Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

  9. Pelvic rotation torque during fast-pitch softball hitting under three ball height conditions.

    PubMed

    Iino, Yoichi; Fukushima, Atsushi; Kojima, Takeji

    2014-08-01

    The purpose of this study was to investigate the relevance of hip joint angles to the production of the pelvic rotation torque in fast-pitch softball hitting and to examine the effect of ball height on this production. Thirteen advanced female softball players hit stationary balls at three different heights: high, middle, and low. The pelvic rotation torque, defined as the torque acting on the pelvis through the hip joints about the pelvic superior-inferior axis, was determined from the kinematic and force plate data using inverse dynamics. Irrespective of the ball heights, the rear hip extension, rear hip external rotation, front hip adduction, and front hip flexion torques contributed to the production of pelvic rotation torque. Although the contributions of the adduction and external rotation torques at each hip joint were significantly different among the ball heights, the contributions of the front and rear hip joint torques were similar among the three ball heights owing to cancelation of the two torque components. The timings of the peaks of the hip joint torque components were significantly different, suggesting that softball hitters may need to adjust the timings of the torque exertions fairly precisely to rotate the upper body effectively. PMID:24979815

  10. Bevel gear driver and method having torque limit selection

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1994-01-01

    This invention comprises a torque drive mechanism utilizing axially translatable, mutually engageable transmission members having mating crown gears, driven and driving members with a three-element drive train being biased together by resilient means or by a fluid actuator system, the apparatus being operable to transmit a precisely controlled degree of torque to a driven member. The apparatus is applicable for use in hand tools and as a replacement for impact torque drivers, torque wrenches, motorized screw drivers, or the like, wherein the applied torque must be precisely controlled or limited. The bevel torque drive includes a drive gear which is axially displaceable and rotatable within cylindrical driver housing, a rotatable intermediate gear, and an output gear. Key rotationally secures displaceable gear with respect to input shaft but permits axial movement therebetween. A thrust bearing is preferably connected to the lower end of shaft for support to reduce play and friction between shaft and a transmission joint disc during rotation of the gear train. Coaxially mounted coiled spring is footed against displaceable gear for biasing the displaceable gear toward and into engagement with the intermediate gear for driving intermediate gear and output gear. Torque control is achieved by the use of straight or spiral beveled gears which are of configurations adapted to withdraw from mutual engagement upon the torque exceeding a predetermined limit. The novel, advantageous features of the invention include the configuration of the mating, crown gear sets and the axially translatable, slidable drive gear. The mechanism is capable of transmitting a high degree of torque within a narrow, compact transmission housing. The compact size and narrow, elongated configuration of the housing is particularly applicable for use in hand tools and in multiple torque driver mechanisms in which it is necessary to drive multiple fasteners which are located in close proximity. Prior

  11. van der Waals torque

    NASA Astrophysics Data System (ADS)

    Esquivel-Sirvent, Raul; Schatz, George

    2014-03-01

    The theory of generalized van der Waals forces by Lifshtz when applied to optically anisotropic media predicts the existence of a torque. In this work we present a theoretical calculation of the van der Waals torque for two systems. First we consider two isotropic parallel plates where the anisotropy is induced using an external magnetic field. The anisotropy will in turn induce a torque. As a case study we consider III-IV semiconductors such as InSb that can support magneto plasmons. The calculations of the torque are done in the Voigt configuration, that occurs when the magnetic field is parallel to the surface of the slabs. The change in the dielectric function as the magnetic field increases has the effect of decreasing the van der Waals force and increasing the torque. Thus, the external magnetic field is used to tune both the force and torque. The second example we present is the use of the torque in the non retarded regime to align arrays of nano particle slabs. The torque is calculated within Barash and Ginzburg formalism in the nonretarded limit, and is quantified by the introduction of a Hamaker torque constant. Calculations are conducted between anisotropic slabs of materials including BaTiO3 and arrays of Ag nano particles. Depending on the shape and arrangement of the Ag nano particles the effective dielectric function of the array can be tuned as to make it more or less anisotropic. We show how this torque can be used in self assembly of arrays of nano particles. ref. R. Esquivel-Sirvent, G. C. Schatz, Phys. Chem C, 117, 5492 (2013). partial support from DGAPA-UNAM.

  12. Experimental Observations for Determining the Maximum Torque Values to Apply to Composite Components Mechanically Joined With Fasteners (MSFC Center Director's Discretionary Fund Final Report, Proj. 03-13}

    NASA Technical Reports Server (NTRS)

    Thomas, F. P.

    2006-01-01

    Aerospace structures utilize innovative, lightweight composite materials for exploration activities. These structural components, due to various reasons including size limitations, manufacturing facilities, contractual obligations, or particular design requirements, will have to be joined. The common methodologies for joining composite components are the adhesively bonded and mechanically fastened joints and, in certain instances, both methods are simultaneously incorporated into the design. Guidelines and recommendations exist for engineers to develop design criteria and analyze and test composites. However, there are no guidelines or recommendations based on analysis or test data to specify a torque or torque range to apply to metallic mechanical fasteners used to join composite components. Utilizing the torque tension machine at NASA s Marshall Space Flight Center, an initial series of tests were conducted to determine the maximum torque that could be applied to a composite specimen. Acoustic emissions were used to nondestructively assess the specimens during the tests and thermographic imaging after the tests.

  13. AX-5 space suit bearing torque investigation

    NASA Technical Reports Server (NTRS)

    Loewenthal, Stuart; Vykukal, Vic; Mackendrick, Robert; Culbertson, Philip, Jr.

    1990-01-01

    The symptoms and eventual resolution of a torque increase problem occurring with ball bearings in the joints of the AX-5 space suit are described. Starting torques that rose 5 to 10 times initial levels were observed in crew evaluation tests of the suit in a zero-g water tank. This bearing problem was identified as a blocking torque anomaly, observed previously in oscillatory gimbal bearings. A large matrix of lubricants, ball separator designs and materials were evaluated. None of these combinations showed sufficient tolerance to lubricant washout when repeatedly cycled in water. The problem was resolved by retrofitting a pressure compensated, water exclusion seal to the outboard side of the bearing cavity. The symptoms and possible remedies to blocking are discussed.

  14. Muscle synergy control model-tuned EMG driven torque estimation system with a musculo-skeletal model.

    PubMed

    Min, Kyuengbo; Shin, Duk; Lee, Jongho; Kakei, Shinji

    2013-01-01

    Muscle activity is the final signal for motion control from the brain. Based on this biological characteristic, Electromyogram (EMG) signals have been applied to various systems that interface human with external environments such as external devices. In order to use EMG signals as input control signal for this kind of system, the current EMG driven torque estimation models generally employ the mathematical model that estimates the nonlinear transformation function between the input signal and the output torque. However, these models need to estimate too many parameters and this process cause its estimation versatility in various conditions to be poor. Moreover, as these models are designed to estimate the joint torque, the input EMG signals are tuned out of consideration for the physiological synergetic contributions of multiple muscles for motion control. To overcome these problems of the current models, we proposed a new tuning model based on the synergy control mechanism between multiple muscles in the cortico-spinal tract. With this synergetic tuning model, the estimated contribution of multiple muscles for the motion control is applied to tune the EMG signals. Thus, this cortico-spinal control mechanism-based process improves the precision of torque estimation. This system is basically a forward dynamics model that transforms EMG signals into the joint torque. It should be emphasized that this forward dynamics model uses a musculo-skeletal model as a constraint. The musculo-skeletal model is designed with precise musculo-skeletal data, such as origins and insertions of individual muscles or maximum muscle force. Compared with the mathematical model, the proposed model can be a versatile model for the torque estimation in the various conditions and estimates the torque with improved accuracy. In this paper, we also show some preliminary experimental results for the discussion about the proposed model. PMID:24110476

  15. Using joint activity schedules to promote peer engagement in preschoolers with autism.

    PubMed

    Betz, Alison; Higbee, Thomas S; Reagon, Kara A

    2008-01-01

    We assessed the use of a joint activity schedule to increase peer engagement for preschoolers with autism. We taught 3 dyads of preschoolers with autism to follow joint activity schedules that cued both members of the pair to play a sequence of interactive games together. Results indicated that joint activity schedules increased peer engagement and the number of games completed for all dyads. Schedule following was maintained without additional prompting when activities were resequenced and when new games were introduced for 2 of the 3 dyads. PMID:18595287

  16. Joint Impedance Decreases during Movement Initiation

    PubMed Central

    Ludvig, Daniel; Antos, Stephen A.; Perreault, Eric J.

    2013-01-01

    The mechanical properties of the joint influence how we interact with our environment and hence are important in the control of both posture and movement. Many studies have investigated how the mechanical properties—specifically the impedance—of different joints vary with different postural tasks. However, studies on how joint impedance varies with movement remain limited. The few studies that have investigated how impedance varies with movement have found that impedance is lower during movement than during posture. In this study we investigated how impedance changed as people transitioned from a postural task to a movement task. We found that subjects’ joint impedances decreased at the initiation of movement, prior to increasing at the cessation of movement. This decrease in impedance occurred even though the subjects’ torque and EMG levels increased. These findings suggest that during movement the central nervous system may control joint impedance independently of muscle activation. PMID:23366632

  17. Three-dimensional motion of the upper extremity joints during various activities of daily living.

    PubMed

    Aizawa, Junya; Masuda, Tadashi; Koyama, Takayuki; Nakamaru, Koji; Isozaki, Koji; Okawa, Atsushi; Morita, Sadao

    2010-11-16

    Highly reliable information on the range of motion (ROM) required to perform activities of daily living (ADL) is important to allow rehabilitation professionals to make appropriate clinical judgments of patients with limited ROM of the upper extremity joints. There are, however, no data available that take full account of corrections for gimbal-lock and soft tissue artifacts, which affect estimation errors for joint angles. We used an electromagnetic three-dimensional tracking system (FASTRAK) to measure the three-dimensional ROM of the upper extremity joints of healthy adults (N=20, age range 18-34) during 16 ADL movement tasks. The ROM required for the performance of each movement was shown in terms of the joint angle at the completion of the task, using a new definition of joint angle and regression analysis to compensate for estimation errors. The results of this study may be useful in setting goals for the treatment of upper extremity joint function. PMID:20727523

  18. Torque Control of a Rehabilitation Teaching Robot Using Magneto-Rheological Fluid Clutches

    NASA Astrophysics Data System (ADS)

    Hakogi, Hokuto; Ohaba, Motoyoshi; Kuramochi, Naimu; Yano, Hidenori

    A new robot that makes use of MR-fluid clutches for simulating torque is proposed to provide an appropriate device for training physical therapy students in knee-joint rehabilitation. The feeling of torque provided by the robot is expected to correspond to the torque performance obtained by physical therapy experts in a clinical setting. The torque required for knee-joint rehabilitation, which is a function of the rotational angle and the rotational angular velocity of a knee movement, is modeled using a mechanical system composed of typical spring-mass-damper elements. The robot consists of two MR-fluid clutches, two induction motors, and a feedback control system. In the torque experiments, output torque is controlled using the spring and damper coefficients separately. The values of these coefficients are determined experimentally. The experimental results show that the robot would be suitable for training physical therapy students to experience similar torque feelings as needed in a clinical situation.

  19. "Nonfloating" universal joint

    NASA Technical Reports Server (NTRS)

    Appleberry, W. T.

    1978-01-01

    Modified crowned-spline joint is lightweight, durable, and requires minimum of parts. It does not use rubber cushions to limit play and is useful over wide temperature range. It has inner ball and socket to provide rigid connection with no axial play. Joint can be adapted to form pinned connection between segmented torque tubes.

  20. Biological activity of polyethylene wear debris produced in the patellofemoral joint.

    PubMed

    Ellison, Peter; Tipper, Joanne L; Jennings, Louise M; Fisher, John

    2012-05-01

    Polyethylene wear is considered a threat to the long-term survival of total knee replacements. The aim of this study was to investigate the contribution that resurfacing the patella makes to wear debris-induced osteolysis following total knee replacement. Ultra-high molecular-weight polyethylene wear particles were isolated from simulator lubricant. Particle shape, size, and volume distributions were recorded allowing the osteolytic potential of the wear debris produced in the patellofemoral joint to be estimated using the concept of specific biological activity and functional biological activity. Values were compared with those reported for the tibiofemoral joint. Specific biological activity for the patellofemoral joint was not significantly different from the values for the tibiofemoral joint of total knee replacement devices, and therefore, has a similar potential to stimulate osteolytic cytokine release from macrophages. Functional biological activity was significantly lower for the patellofemoral joint compared with the tibiofemoral joint. Functional biological activity was significantly lower for the patellofemoral joint compared with the fixed bearing and rotating platform total knee replacement devices. However, as patellar resurfacing is commonly fitted as part of a total knee replacement system, this results in a 20% increase in overall functional biological activity for the system. Therefore, implanting a patellar resurfacing will increase the potential for osteolysis in the knee. PMID:22720390

  1. An experimental comparison of the relative benefits of work and torque assistance in ankle exoskeletons.

    PubMed

    Jackson, Rachel W; Collins, Steven H

    2015-09-01

    Techniques proposed for assisting locomotion with exoskeletons have often included a combination of active work input and passive torque support, but the physiological effects of different assistance techniques remain unclear. We performed an experiment to study the independent effects of net exoskeleton work and average exoskeleton torque on human locomotion. Subjects wore a unilateral ankle exoskeleton and walked on a treadmill at 1.25 m·s(-1) while net exoskeleton work rate was systematically varied from -0.054 to 0.25 J·kg(-1)·s(-1), with constant (0.12 N·m·kg(-1)) average exoskeleton torque, and while average exoskeleton torque was systematically varied from approximately zero to 0.18 N·m·kg(-1), with approximately zero net exoskeleton work. We measured metabolic rate, center-of-mass mechanics, joint mechanics, and muscle activity. Both techniques reduced effort-related measures at the assisted ankle, but this form of work input reduced metabolic cost (-17% with maximum net work input) while this form of torque support increased metabolic cost (+13% with maximum average torque). Disparate effects on metabolic rate seem to be due to cascading effects on whole body coordination, particularly related to assisted ankle muscle dynamics and the effects of trailing ankle behavior on leading leg mechanics during double support. It would be difficult to predict these results using simple walking models without muscles or musculoskeletal models that assume fixed kinematics or kinetics. Data from this experiment can be used to improve predictive models of human neuromuscular adaptation and guide the design of assistive devices. PMID:26159764

  2. Fabricated torque shaft

    DOEpatents

    Mashey, Thomas Charles

    2002-01-01

    A fabricated torque shaft is provided that features a bolt-together design to allow vane schedule revisions with minimal hardware cost. The bolt-together design further facilitates on-site vane schedule revisions with parts that are comparatively small. The fabricated torque shaft also accommodates stage schedules that are different one from another in non-linear inter-relationships as well as non-linear schedules for a particular stage of vanes.

  3. Improvement on output torque of dielectric elastomer minimum energy structures

    NASA Astrophysics Data System (ADS)

    Zhao, Jianwen; Niu, Junyang; McCoul, David; Ge, Yong; Pei, Qibing; Liu, Liwu; Leng, Jinsong

    2015-08-01

    The dielectric elastomer minimum energy structure (DEMES) can realize large angular deformations by a small voltage-induced strain of the dielectric elastomer (DE), so it is a suitable candidate to make a rotary joint for a soft robot. However, the payload capacity of a DEMES joint is small compared with other types of dielectric elastomer actuators. Stacking layers of pre-strained DE thin films can increase the output torque of DEMES, but greater driving power will be needed, limiting application in mobile or flying soft robots. In this paper, based on static analysis, a design of DEMES is proposed that has larger torque than the traditional design with the same number of layers of dielectric elastomer. As an experimental example, the torque of the film with the improved design is larger than 1.7 times that of the traditional design. Experiments validate the theoretical analysis and demonstrate the improvement of DEMES output torque.

  4. Displaceable Gear Torque Controlled Driver

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1997-01-01

    Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.

  5. A torque sensing technique for robots with harmonic drives

    SciTech Connect

    Hashimoto, M. . Dept. of Mechanical Engineering); Kiyosawa, Yoshihide ); Paul, R.P. . Dept. of Computer Information Science)

    1993-02-01

    The authors propose a joint torque sensing technique making use of the existing structural elasticity of robots. The technique provides joint torque sensing without reducing the stiffness of the robot or changing the mechanical structure of the joints. The elasticity of the flexsplines of the harmonic drives is utilized to measure the joint torque. The flexsplines are flexible thin cups, made from steel, in the harmonic drives that are driven by the wave generators. In this paper, they perform a finite-element analysis of the flexsplines that shows that a special configuration of strain gauges, mounted on the flexspline, has to be employed to eliminate errors in sensor information due to rotation of the wave generator. Characteristics of the torque sensor are then examined experimentally. The linearity and the dynamic response are almost the same as those of a conventional sensing technique. Joint torque control, using the proposed sensor, is implemented for a one-link robot arm. Both theoretical and experimental investigations support the validity of the proposed sensing technique.

  6. Textured bearing surface in artificial joints to reduce macrophage activation

    NASA Astrophysics Data System (ADS)

    Nakanishi, Yoshitaka; Nishi, Naoki; Chikaura, Hiroto; Nakashima, Yuta; Miura, Hiromasa; Higaki, Hidehiko; Mizuta, Hiroshi; Iwamoto, Yukihide; Fujiwara, Yukio; Komohara, Yoshihiro; Takeya, Motohiro

    2015-12-01

    Micro slurry-jet erosion has been proposed as a precision machining technique for the bearing surfaces of artificial joints in order to reduce the total amount of polyethylene wear and to enlarge the size of the wear debris. The micro slurry-jet erosion method is a wet blasting technique which uses alumina particles as the abrasive medium along with compressed air and water to create an ideal surface. Pin-on-disc wear tests with multidirectional sliding motion on the textured surface of a \\text{Co}-\\text{Cr}-\\text{Mo} alloy counterface for polyethylene resulted in both a reduction of wear as well as enlargement of the polyethylene debris size. In this study, primary human peripheral blood mononuclear phagocytes were incubated with the debris, and it was elucidated that the wear debris generated on the textured surface regulated secretion of the proinflammatory cytokines IL-6 and TNF-α, indicating a reduction in the induced tissue reaction and joint loosening.

  7. Orion - Super Koropon(Registered Trademark) Torque/Tension Report

    NASA Technical Reports Server (NTRS)

    Hemminger, Edgar G.; McLeod, Christopher; Peil, John

    2012-01-01

    The primary objective of this testing was to obtain torque tension data for the use of Super Koropon Primer Base which was proposed for use on the Orion project. This compound is a corrosion inhibitor/sealer used on threaded fasteners and inserts as specified per NASA/JSC PRC-4004, Sealing of Joints and Faying Surfaces. Some secondary objectives of this testing, were to identify the effect on torque coefficient of several variables. This document contains the outcome of the testing.

  8. Torque and mechanomyogram relationships during electrically-evoked isometric quadriceps contractions in persons with spinal cord injury.

    PubMed

    Ibitoye, Morufu Olusola; Hamzaid, Nur Azah; Hasnan, Nazirah; Abdul Wahab, Ahmad Khairi; Islam, Md Anamul; Kean, Victor S P; Davis, Glen M

    2016-08-01

    The interaction between muscle contractions and joint loading produces torques necessary for movements during activities of daily living. However, during neuromuscular electrical stimulation (NMES)-evoked contractions in persons with spinal cord injury (SCI), a simple and reliable proxy of torque at the muscle level has been minimally investigated. Thus, the purpose of this study was to investigate the relationships between muscle mechanomyographic (MMG) characteristics and NMES-evoked isometric quadriceps torques in persons with motor complete SCI. Six SCI participants with lesion levels below C4 [(mean (SD) age, 39.2 (7.9) year; stature, 1.71 (0.05) m; and body mass, 69.3 (12.9) kg)] performed randomly ordered NMES-evoked isometric leg muscle contractions at 30°, 60° and 90° knee flexion angles on an isokinetic dynamometer. MMG signals were detected by an accelerometer-based vibromyographic sensor placed over the belly of rectus femoris muscle. The relationship between MMG root mean square (MMG-RMS) and NMES-evoked torque revealed a very high association (R(2)=0.91 at 30°; R(2)=0.98 at 60°; and R(2)=0.97 at 90° knee angles; P<0.001). MMG peak-to-peak (MMG-PTP) and stimulation intensity were less well related (R(2)=0.63 at 30°; R(2)=0.67 at 60°; and R(2)=0.45 at 90° knee angles), although were still significantly associated (P≤0.006). Test-retest interclass correlation coefficients (ICC) for the dependent variables ranged from 0.82 to 0.97 for NMES-evoked torque, between 0.65 and 0.79 for MMG-RMS, and from 0.67 to 0.73 for MMG-PTP. Their standard error of measurements (SEM) ranged between 10.1% and 31.6% (of mean values) for torque, MMG-RMS and MMG-PTP. The MMG peak frequency (MMG-PF) of 30Hz approximated the stimulation frequency, indicating NMES-evoked motor unit firing rate. The results demonstrated knee angle differences in the MMG-RMS versus NMES-isometric torque relationship, but a similar torque related pattern for MMG-PF. These findings

  9. The effect of an active vibration stimulus according to different shoulder joint angles on functional reach and stability of the shoulder joint

    PubMed Central

    Kim, Eun-Kyung; Kim, Seong-Gil

    2016-01-01

    [Purpose] The purpose of this study was to analyze the effect of an active vibration stimulus exercise according to shoulder joint angles on functional reach and stability of the shoulder joint. [Subjects and Methods] Thirty healthy male students participated in this study. Upper limb length of each subject was measured to obtain normalized measurement values. The exercise groups were as follows: group I (n=10, shoulder joint angle of 90°), group II (n=10, shoulder joint angle of 130°), and group III (n=10, shoulder joint angle of 180°). After warm-up, an active vibration stimulus was applied to the subjects with a Flexi-Bar. The Functional Reach Test and Y-balance test were conducted for measurement of shoulder stability. [Results] Analysis of covariance was conducted with values before the intervention as covariates to analyze the differences among the groups in the two tests. There were significant differences among the groups. According to Bonferroni post hoc comparison, group I showed greater improvement than group III in the Functional Reach Test, and group II showed greater improvement than group I and group III in the Y-balance test. [Conclusion] The effect of the exercise with different shoulder joint angles revealed that the shoulder joint has a certain effective joint angle for its functionality and stability. In addition, application of an active vibration stimulus with a Flexi-Bar can be a very effective tool for improvement of functionality and stability of the shoulder joint. PMID:27134352

  10. Method for analyzing articulated torques of heavy-duty six-legged robot

    NASA Astrophysics Data System (ADS)

    Zhuang, Hongchao; Gao, Haibo; Ding, Liang; Liu, Zhen; Deng, Zongquan

    2013-07-01

    The accuracy of an articulated torque analysis influences the comprehensive performances of heavy-duty multi-legged robots. Currently, the extremal estimation method and some complex methods are employed to calculate the articulated torques, which results in a large safety margin or a large number of calculations. To quickly obtain accurate articulated torques, an analysis method for the articulated torque is presented for an electrically driven heavy-duty six-legged robot. First, the rearmost leg that experiences the maximum normal contact force is confirmed when the robot transits a slope. Based on the ant-type and crab-type tripod gaits, the formulas of classical mechanics and MATLAB software are employed to theoretically analyze the relevant static torques of the joints. With the changes in the joint angles for the abductor joint, hip joint, and knee joint, variable tendency charts and extreme curves are obtained for the static articulated torques. Meanwhile, the maximum static articulated torques and the corresponding poses of the robot are also obtained. According to the poses of the robot under the maximum static articulated torques, ADAMS software is used to carry out a static simulation analysis. Based on the relevant simulation curves of the articulated torques, the maximum static articulated torques are acquired. A comparative analysis of the maximum static articulated torques shows that the theoretical calculation values are higher than the static simulation values, and the maximum error value is approximately 10%. The proposed method lays a foundation for quickly determining accurate articulated torques to develop heavy-duty six-legged robots.

  11. Acceleration and torque feedback for robotic control - Experimental results

    NASA Technical Reports Server (NTRS)

    Mclnroy, John E.; Saridis, George N.

    1990-01-01

    Gross motion control of robotic manipulators typically requires significant on-line computations to compensate for nonlinear dynamics due to gravity, Coriolis, centripetal, and friction nonlinearities. One controller proposed by Luo and Saridis avoids these computations by feeding back joint acceleration and torque. This study implements the controller on a Puma 600 robotic manipulator. Joint acceleration measurement is obtained by measuring linear accelerations of each joint, and deriving a computationally efficient transformation from the linear measurements to the angular accelerations. Torque feedback is obtained by using the previous torque sent to the joints. The implementation has stability problems on the Puma 600 due to the extremely high gains inherent in the feedback structure. Since these high gains excite frequency modes in the Puma 600, the algorithm is modified to decrease the gain inherent in the feedback structure. The resulting compensator is stable and insensitive to high frequency unmodeled dynamics. Moreover, a second compensator is proposed which uses acceleration and torque feedback, but still allows nonlinear terms to be fed forward. Thus, by feeding the increment in the easily calculated gravity terms forward, improved responses are obtained. Both proposed compensators are implemented, and the real time results are compared to those obtained with the computed torque algorithm.

  12. Well pipe joint

    SciTech Connect

    Ortloff, D.J.; Landriault, L.S.

    1987-08-25

    For use in forming a pipe joint, a threaded tubular member adapted for connecting to another threaded member to form a threaded connection between the two members is described comprising a tubular body, a projecting helical rib on the body forming screw threads having load flanks shaped to have clearance between the flanks of the thread and the load flanks of the threads of the threaded member to which the member is adapted to be connected and a torque shoulder on the body to engage a torque shoulder on the other threaded member as the connection is being made up to limit the distance one of the members can enter the other for a given make-up torque. The threads are formed on the body so that selected threads away from the torque shoulder will have less clearance between them and the mating threads on the other member than do the threads on the member adjacent the torque shoulder and the mating threads on the other member when the torque shoulders engage so that the selected threads will engage the mating threads on the other member before the other threads adjacent the torque shoulder and the mating threads on the other member engage to cause the selected threads to be loaded initially to provide the initial force between the torque shoulders and to more uniformly load all of the threads when the connection is made-up and additional external loads are applied.

  13. Negative Optical Torque

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Ng, Jack; Ding, Kun; Fung, Kin Hung; Lin, Zhifang; Chan, C. T.

    2014-09-01

    Light carries angular momentum, and as such it can exert torques on material objects. Applications of these opto-mechanical effects were limited initially due to their smallness in magnitude, but later becomes powerful and versatile after the invention of laser. Novel and practical approaches for harvesting light for particle rotation have since been demonstrated, where the structure is always subjected to a positive optical torque along a certain axis if the incident angular momentum has a positive projection on the same axis. We report here an interesting phenomenon of ``negative optical torque'', meaning that incoming photons carrying angular momentum rotate an object in the opposite sense. Surprisingly this can be realized quite straightforwardly in simple planar structures. Field retardation is a necessary condition and discrete rotational symmetry of material object plays an important role. The optimal conditions are explored and explained.

  14. Ironless armature torque motor

    NASA Technical Reports Server (NTRS)

    Fisher, R. L.

    1972-01-01

    Four iron-less armature torque motors, four Hall device position sensor assemblies, and two test fixtures were fabricated. The design approach utilized samarium cobalt permanent magnets, a large airgap, and a three-phase winding in a stationary ironless armature. Hall devices were employed to sense rotor position. An ironless armature torque motor having an outer diameter of 4.25 inches was developed to produce a torque constant of 65 ounce-inches per ampere with a resistance of 20.5 ohms. The total weight, including structural elements, was 1.58 pounds. Test results indicated that all specifications were met except for generated voltage waveform. It is recommended that investigations be made concerning the generated voltage waveform to determine if it may be improved.

  15. Semi-active damping of large space truss structures using friction joints

    NASA Astrophysics Data System (ADS)

    Gaul, Lothar; Albrecht, Hans; Wirnitzer, Jan

    2002-11-01

    The low structural damping of large space structures and the stringent positioning requirements in missions demand effective vibration suppression. The semi-active approach at hand is based on friction damping due to interfacial slip in semi-active joints which can be controlled by varying the normal pressure in the contact area using a piezo-stack actuator. This paper focuses on the modeling, identification and model reduction of a large space structure with semi-active joints. For the purpose of model identification and model reduction, the nonlinear friction forces transmitted in the joints are considered as external forces acting on the linear tress structure. Experimental Modal Analysis results are used to update the FE model of the truss structure and the parameters of the nonlinear friction model are identified from measured responses of an isolated joint. The model of the linear subsystem is reduced by a combination of balanced reduction and matching moments method. The modal truncation is based on controllability and observability gramians. To improve the fidelity locations conventional connections are replaced by adaptive joints, each with a local feedback controller for the adaptation of the normal force. Simulation results of a 10-bay truss structure with semi-active joints show the potential of the present approach.

  16. Exploring the Neural Basis of Real-Life Joint Action: Measuring Brain Activation during Joint Table Setting with Functional Near-Infrared Spectroscopy

    PubMed Central

    Egetemeir, Johanna; Stenneken, Prisca; Koehler, Saskia; Fallgatter, Andreas J.; Herrmann, Martin J.

    2011-01-01

    Many every-day life situations require two or more individuals to execute actions together. Assessing brain activation during naturalistic tasks to uncover relevant processes underlying such real-life joint action situations has remained a methodological challenge. In the present study, we introduce a novel joint action paradigm that enables the assessment of brain activation during real-life joint action tasks using functional near-infrared spectroscopy (fNIRS). We monitored brain activation of participants who coordinated complex actions with a partner sitting opposite them. Participants performed table setting tasks, either alone (solo action) or in cooperation with a partner (joint action), or they observed the partner performing the task (action observation). Comparing joint action and solo action revealed stronger activation (higher [oxy-Hb]-concentration) during joint action in a number of areas. Among these were areas in the inferior parietal lobule (IPL) that additionally showed an overlap of activation during action observation and solo action. Areas with such a close link between action observation and action execution have been associated with action simulation processes. The magnitude of activation in these IPL areas also varied according to joint action type and its respective demand on action simulation. The results validate fNIRS as an imaging technique for exploring the functional correlates of interindividual action coordination in real-life settings and suggest that coordinating actions in real-life situations requires simulating the actions of the partner. PMID:21927603

  17. Glenohumeral Joint Preservation: A Review of Management Options for Young, Active Patients with Osteoarthritis

    PubMed Central

    van der Meijden, Olivier A.; Gaskill, Trevor R.; Millett, Peter J.

    2012-01-01

    The management of osteoarthritis of the shoulder in young, active patients is a challenge, and the optimal treatment has yet to be completely established. Many of these patients wish to maintain a high level of activity, and arthroplasty may not be a practical treatment option. It is these patients who may be excellent candidates for joint-preservation procedures in an effort to avoid or delay joint replacement. Several palliative and restorative techniques are currently optional. Joint debridement has shown good results and a combination of arthroscopic debridement with a capsular release, humeral osteoplasty, and transcapsular axillary nerve decompression seems promising when humeral osteophytes are present. Currently, microfracture seems the most studied reparative treatment modality available. Other techniques, such as autologous chondrocyte implantation and osteochondral transfers, have reportedly shown potential but are currently mainly still investigational procedures. This paper gives an overview of the currently available joint preserving surgical techniques for glenohumeral osteoarthritis. PMID:22536514

  18. Abdominal muscle activity according to knee joint angle during sit-to-stand

    PubMed Central

    Eom, Juri; Rhee, Min-Hyung; Kim, Laurentius Jongsoon

    2016-01-01

    [Purpose] This study assessed the activity of the abdominal muscles according to the angle of the knee joints during sit-to-stand. [Subjects and Methods] Thirty healthy adult males participated in this study. Subjects initiated sit-to-stand at knee joint angles of 60°, 90°, or 120°. An electromyography system was used to measure the maximum voluntary isometric contraction of the rectus abdominis, external oblique, and internal oblique and transverse abdominis muscles. [Results] Percent contraction differed significantly among the three knee joint angles, most notably for the internal oblique and transverse abdominis muscles. [Conclusion] Wider knee joint angles more effectively activate the abdominal muscles, especially those in the deep abdomen, than do narrower angles. PMID:27390431

  19. Torque Control of Underactuated Tendon-driven Robotic Fingers

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E. (Inventor); Ihrke, Chris A. (Inventor); Reiland, Matthew J. (Inventor); Wampler, Charles W. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Bridgwater, Lyndon (Inventor)

    2013-01-01

    A robotic system includes a robot having a total number of degrees of freedom (DOF) equal to at least n, an underactuated tendon-driven finger driven by n tendons and n DOF, the finger having at least two joints, being characterized by an asymmetrical joint radius in one embodiment. A controller is in communication with the robot, and controls actuation of the tendon-driven finger using force control. Operating the finger with force control on the tendons, rather than position control, eliminates the unconstrained slack-space that would have otherwise existed. The controller may utilize the asymmetrical joint radii to independently command joint torques. A method of controlling the finger includes commanding either independent or parameterized joint torques to the controller to actuate the fingers via force control on the tendons.

  20. Using min-max of torque to resolve redundancy for a mobile manipulator

    SciTech Connect

    Reister, D.B.

    1991-01-01

    We have considered the problem of determining the time trajectories of the joint variables of a mobile manipulator with many redundant degrees of freedom that will minimize the maximum value of the torque during a large scale motion by the manipulator. Conventional search techniques slowly solve min-max problems. Based on well known results from the Tchebycheff approximation of functions, we conjecture that at the min-max the magnitude of the normalized torques will be equal at all of the joints. It is an easier problem to find the values of the joint variables that equalize the torques than to perform a large set of slow searches. Furthermore, paths that equate the torques are likely to be continuous in joint space. We have explored paths that equalize the magnitude of the normalized torques for a three link planar manipulator on a platform and for the seven degree of freedom CESARm on a three degree of freedom platform. For the planar arm, we find many analytical solutions that minimize the torque in various regions of the workspace. For the CESARm, the most attractive solution covers a wide range of the workspace and has only one discontinuity in a joint variable. We have found paths that can bridge the discontinuity at a small penalty of increased torque. Paths that equate the torques are attractive candidates for large scale motion by a mobile manipulator. 4 refs., 12 figs.

  1. Linking wheelchair kinetics to glenohumeral joint demand during everyday accessibility activities.

    PubMed

    Holloway, Catherine S; Symonds, Andrew; Suzuki, Tatsuto; Gall, Angela; Smitham, Peter; Taylor, Stephen

    2015-08-01

    The aim of the study was to investigate if push-rim kinetics could be used as markers of glenohumeral joint demand during manual wheelchair accessibility activities; demonstrating a method of biomechanical analysis that could be used away from the laboratory. Propulsion forces, trunk and upper limb kinematics and surface electromyography were recorded during four propulsion tasks (level, 2.5% cross slope, 6.5% incline and 12% incline). Kinetic and kinematic data were applied to an OpenSim musculoskeletal model of the trunk and upper limb, to enable calculation of glenohumeral joint contact force. Results demonstrated a positive correlation between propulsion forces and glenohumeral joint contact forces. Both propulsion forces and joint contact forces increased as the task became more challenging. Participants demonstrated increases in trunk flexion angle as the requirement for force application increased, significantly so in the 12% incline. There were significant increases in both resultant glenohumeral joint contact forces and peak and mean normalized muscle activity levels during the incline tasks. This study demonstrated the high demand placed on the glenohumeral joint during accessibility tasks, especially as the gradient of incline increases. A lightweight instrumented wheelchair wheel has potential to guide the user to minimize upper limb demand during daily activity. PMID:26736796

  2. Thermally driven spin torques in layered magnetic insulators

    NASA Astrophysics Data System (ADS)

    Bender, Scott A.; Tserkovnyak, Yaroslav

    2016-02-01

    Thermally driven spin-transfer torques have recently been reported in electrically insulating ferromagnet |normal -metal heterostructures. In this paper, we propose two physically distinct mechanisms for such torques. The first is a local effect: out-of-equilibrium, thermally activated magnons in the ferromagnet, driven by a spin Seebeck effect, exert a torque on the magnetization via magnon-magnon scattering with coherent dynamics. The second is a nonlocal effect which requires an additional magnetic layer to provide the symmetry breaking necessary to realize a thermal torque. The simplest structure in which to induce a nonlocal thermal torque is a spin valve composed of two insulating magnets separated by a normal metal spacer; there, a thermal flux generates a pure spin current through the spin valve, which results in a torque when the magnetizations of the layers are misaligned.

  3. In vivo human knee joint dynamic properties as functions of muscle contraction and joint position.

    PubMed

    Zhang, L Q; Nuber, G; Butler, J; Bowen, M; Rymer, W Z

    1998-01-01

    Information on the dynamic properties (joint stiffness, viscosity and limb inertia) of the human knee joint is scarce in the literature, especially for actively contracting knee musculature. A joint driving device was developed to apply small-amplitude random perturbations to the human knee at several flexion angles with the subject maintaining various levels of muscle contraction. It was found that joint stiffness and viscosity increased with muscle contraction substantially, while limb inertia was constant. Stiffness produced by the quadriceps was highest at 30 degrees flexion and decreased with increasing or decreasing flexion angle, while knee flexors produced highest stiffness at 90 degree flexion. When knee flexion was < 60 degrees, stiffness produced by the quadriceps was higher than that of the hamstrings and gastrocnemius at the same level of background muscle torque, while knee flexor muscles produced higher stiffnesses than the quadriceps at 90 degree flexion. Similar but less obvious trends were observed for joint viscosity. Passive joint stiffness at full knee extension was significantly higher than in more flexed positions. Surprisingly, as the knee joint musculature changed from relaxed to contracting at 50% MVC, system damping ratio remained at about 0.2. This outcome potentially simplifies neuromuscular control of the knee joint. In contrast, the natural undamped frequency increased more than twofold, potentially making the knee joint respond more quickly to the central nervous system commands. The approach described here provides us with a potentially valuable tool to quantify in vivo dynamic properties of normal and pathological human knee joints. PMID:9596540

  4. Locations of Joint Physical Activity in Parent-Child Pairs Based on Accelerometer and GPS Monitoring

    PubMed Central

    Dunton, Genevieve Fridlund; Liao, Yue; Almanza, Estela; Jerrett, Micheal; Spruijt-Metz, Donna; Pentz, Mary Ann

    2012-01-01

    Background Parental factors may play an important role in influencing children’s physical activity levels. Purpose This cross-sectional study sought to describe the locations of joint physical activity among parents and children. Methods Parent-child pairs (N = 291) wore an Actigraph GT2M accelerometer and GlobalSat BT-335 Global Positioning Systems (GPS) device over the same 7-day period. Children were ages 8–14 years. Joint behavior was defined by a linear separation distance of less than 50m between parent and child. Land use classifications were assigned to GPS data points. Results Joint physical activity was spread across residential locations (35%), and commercial venues (24%), and open spaces/parks (20%). Obese children and parents performed less joint physical activity in open spaces/parks than under/normal weight children and parents (p’s < .01). Conclusions Understanding where joint parent-child physical activity naturally occurs may inform location-based interventions to promote these behaviors. PMID:23011914

  5. Torque Splitting by a Concentric Face Gear Transmission

    NASA Technical Reports Server (NTRS)

    Filler, Robert R.; Heath, Gregory F.; Slaughter, Stephen C.; Lewicki, David G.

    2002-01-01

    Tests of a 167 Kilowatt (224 Horsepower) split torque face gearbox were performed by the Boeing Company in Mesa, Arizona, while working under a Defense Advanced Research Projects Agency (DARPA) Technology Reinvestment Program (TRP). This paper provides a summary of these cooperative tests, which were jointly funded by Boeing and DARPA. Design, manufacture and testing of the scaled-power TRP proof-of-concept (POC) split torque gearbox followed preliminary evaluations of the concept performed early in the program. The split torque tests were run using 200 N-m (1767 in-lbs) torque input to each side of the transmission. During tests, two input pinions were slow rolled while in mesh with the two face gears. Two idler gears were also used in the configuration to recombine torque near the output. Resistance was applied at the output face gear to create the required loading conditions in the gear teeth. A system of weights, pulleys and cables were used in the test rig to provide both the input and output loading. Strain gages applied in the tooth root fillets provided strain indication used to determine torque splitting conditions at the input pinions. The final two pinion-two idler tests indicated 52% to 48% average torque split capabilities for the two pinions. During the same tests, a 57% to 43% average distribution of the torque being recombined to the upper face gear from the lower face gear was measured between the two idlers. The POC split torque tests demonstrated that face gears can be applied effectively in split torque rotorcraft transmissions, yielding good potential for significant weight, cost and reliability improvements over existing equipment using spiral bevel gearing.

  6. Multiple-Cantilever Torque Sensor

    NASA Technical Reports Server (NTRS)

    Lurie, Boris J.; Schier, J. Alan; Socha, Michael

    1989-01-01

    Sensitivity to spurious loads small. High stiffness, high resolution, and ease of fabrication among features of specially designed torque sensor. Device flexible and sensitive to torque about its cylindrical axis and stiff enough to be insensitive to bending about any perpendicular axis. Measures and transmits torque between driving and driven plates.

  7. Torque, Cognitive Ability, and Schooling.

    ERIC Educational Resources Information Center

    Csapo, Marg

    1985-01-01

    West African Hausan Children (N=110) aged 5-6 were administered a torque test and relationshps between the torque task and visual spatial tasks were analyzed. Findings supported the assumption that educational experience related to circling accounts for decrease in torque, or that the educational experiences have potential influence on cortical…

  8. Physical activity in the elderly who underwent joint replacement surgery in the course of rheumatic diseases

    PubMed Central

    Komorowski, Arkadiusz; Przepióra, Wiktor; Księżopolska-Orłowska, Krystyna

    2016-01-01

    According to the forecasts of the Central Statistical Office of Poland, in 2030 people at the age of 65 and older will account for 23.8%, i.e. their number will amount to approx. 8.5 m people. Geriatric rheumatic patients more often decide to undergo surgical joint replacement. According to the National Health Fund, the number of joint replacement services provided in 2014 increased by 93%, as compared to 2005. Improving the physical performance of this constantly expanding group of patients requires taking into account many factors to raise their functional status, reduce the risk of falling, teach rules of proper functioning with an artificial joint and encourage unassisted physical activity. Restoring fitness and independence is a difficult but necessary task due to an increasing number of seniors with replaced joint. PMID:27504021

  9. Physical activity in the elderly who underwent joint replacement surgery in the course of rheumatic diseases.

    PubMed

    Prusinowska, Agnieszka; Komorowski, Arkadiusz; Przepióra, Wiktor; Księżopolska-Orłowska, Krystyna

    2016-01-01

    According to the forecasts of the Central Statistical Office of Poland, in 2030 people at the age of 65 and older will account for 23.8%, i.e. their number will amount to approx. 8.5 m people. Geriatric rheumatic patients more often decide to undergo surgical joint replacement. According to the National Health Fund, the number of joint replacement services provided in 2014 increased by 93%, as compared to 2005. Improving the physical performance of this constantly expanding group of patients requires taking into account many factors to raise their functional status, reduce the risk of falling, teach rules of proper functioning with an artificial joint and encourage unassisted physical activity. Restoring fitness and independence is a difficult but necessary task due to an increasing number of seniors with replaced joint. PMID:27504021

  10. 15 CFR 296.9 - Activities not permitted for joint ventures.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... service that is not reasonably required to conduct the research and development that is the purpose of... INNOVATION PROGRAM General § 296.9 Activities not permitted for joint ventures. The following activities are... restrict or require the sale, licensing, or sharing of inventions or developments not developed...

  11. Creep Deformation and Rupture Behavior of Single- and Dual-Pass 316LN Stainless-Steel-Activated TIG Weld Joints

    NASA Astrophysics Data System (ADS)

    Vijayanand, V. D.; Vasudevan, M.; Ganesan, V.; Parameswaran, P.; Laha, K.; Bhaduri, A. K.

    2016-03-01

    Creep deformation and rupture behavior of single-pass and dual-pass 316LN stainless steel (SS) weld joints fabricated by an autogenous activated tungsten inert gas welding process have been assessed by performing metallography, hardness, and conventional and impression creep tests. The fusion zone of the single-pass joint consisted of columnar zones adjacent to base metals with a central equiaxed zone, which have been modified extensively by the thermal cycle of the second pass in the dual-pass joint. The equiaxed zone in the single-pass joint, as well as in the second pass of the dual-pass joint, displayed the lowest hardness in the joints. In the dual-pass joint, the equiaxed zone of the first pass had hardness comparable to the columnar zone. The hardness variations in the joints influenced the creep deformation. The equiaxed and columnar zone in the first pass of the dual-pass joint was more creep resistant than that of the second pass. Both joints possessed lower creep rupture life than the base metal. However, the creep rupture life of the dual-pass joint was about twofolds more than that of the single-pass joint. Creep failure in the single-pass joint occurred in the central equiaxed fusion zone, whereas creep cavitation that originated in the second pass was blocked at the weld pass interface. The additional interface and strength variation between two passes in the dual-pass joint provides more restraint to creep deformation and crack propagation in the fusion zone, resulting in an increase in the creep rupture life of the dual-pass joint over the single-pass joint. Furthermore, the differences in content, morphology, and distribution of delta ferrite in the fusion zone of the joints favors more creep cavitation resistance in the dual-pass joint over the single-pass joint with the enhancement of creep rupture life.

  12. Creep Deformation and Rupture Behavior of Single- and Dual-Pass 316LN Stainless-Steel-Activated TIG Weld Joints

    NASA Astrophysics Data System (ADS)

    Vijayanand, V. D.; Vasudevan, M.; Ganesan, V.; Parameswaran, P.; Laha, K.; Bhaduri, A. K.

    2016-06-01

    Creep deformation and rupture behavior of single-pass and dual-pass 316LN stainless steel (SS) weld joints fabricated by an autogenous activated tungsten inert gas welding process have been assessed by performing metallography, hardness, and conventional and impression creep tests. The fusion zone of the single-pass joint consisted of columnar zones adjacent to base metals with a central equiaxed zone, which have been modified extensively by the thermal cycle of the second pass in the dual-pass joint. The equiaxed zone in the single-pass joint, as well as in the second pass of the dual-pass joint, displayed the lowest hardness in the joints. In the dual-pass joint, the equiaxed zone of the first pass had hardness comparable to the columnar zone. The hardness variations in the joints influenced the creep deformation. The equiaxed and columnar zone in the first pass of the dual-pass joint was more creep resistant than that of the second pass. Both joints possessed lower creep rupture life than the base metal. However, the creep rupture life of the dual-pass joint was about twofolds more than that of the single-pass joint. Creep failure in the single-pass joint occurred in the central equiaxed fusion zone, whereas creep cavitation that originated in the second pass was blocked at the weld pass interface. The additional interface and strength variation between two passes in the dual-pass joint provides more restraint to creep deformation and crack propagation in the fusion zone, resulting in an increase in the creep rupture life of the dual-pass joint over the single-pass joint. Furthermore, the differences in content, morphology, and distribution of delta ferrite in the fusion zone of the joints favors more creep cavitation resistance in the dual-pass joint over the single-pass joint with the enhancement of creep rupture life.

  13. Elbow and wrist joint contact forces during occupational pick and place activities.

    PubMed

    Chadwick, E K; Nicol, A C

    2000-05-01

    A three-dimensional, mathematical model of the elbow and wrist joints, including 15 muscle units, 3 ligaments and 4 joint forces, has been developed. A new strain gauge transducer has been developed to measure functional grip forces. The device measures radial forces divided into six components and forces of up to 250N per segment can be measured with an accuracy of +/-1%. Ten normal volunteers were asked to complete four tasks representing occupational activities, during which time their grip force was monitored. Together with kinematic information from the six-camera Vicon data, the moment effect of these loads at the joints was calculated. These external moments are assumed to be balanced by the internal moments, generated by the muscles, passive soft tissue and bone contact. The effectiveness of the body's internal structures in generating joint moments was assessed by studying the geometry of a simplified model of the structures, where information about the lines of action and moment arms of muscles, tendons and ligaments is contained. The assumption of equilibrium between these external and internal joint moments allows formulation of a set of equations from which muscle and joint forces can be calculated. A two stage, linear optimisation routine minimising the overall muscle stress and the sum of the joint forces has been used to overcome the force-sharing problem. Humero-ulnar forces of up to 1600N, humero-radial forces of up to 800N and wrist joint forces of up to 2800N were found for moderate level activity. The model was validated by comparison with other studies. PMID:10708780

  14. Coordination of muscle torques stabilizes upright standing posture: an UCM analysis.

    PubMed

    Park, Eunse; Reimann, Hendrik; Schöner, Gregor

    2016-06-01

    The control of upright stance is commonly explained on the basis of the single inverted pendulum model (ankle strategy) or the double inverted pendulum model (combination of ankle and hip strategy). Kinematic analysis using the uncontrolled manifold (UCM) approach suggests, however, that stability in upright standing results from coordinated movement of multiple joints. This is based on evidence that postural sway induces more variance in joint configurations that leave the body position in space invariant than in joint configurations that move the body in space. But does this UCM structure of kinematic variance truly reflect coordination at the level of the neural control strategy or could it result from passive biomechanical factors? To address this question, we applied the UCM approach at the level of muscle torques rather than joint angles. Participants stood on the floor or on a narrow base of support. We estimated torques at the ankle, knee, and hip joints using a model of the body dynamics. We then partitioned the joint torques into contributions from net, motion-dependent, gravitational, and generalized muscle torques. A UCM analysis of the structure of variance of the muscle torque revealed that postural sway induced substantially more variance in directions in muscle torque space that leave the Center of Mass (COM) force invariant than in directions that affect the force acting on the COM. This difference decreased when we decorrelated the muscle torque data by randomizing across time. Our findings show that the UCM structure of variance exists at the level of muscle torques and is thus not merely a by-product of biomechanical coupling. Because muscle torques reflect neural control signals more directly than joint angles do, our results suggest that the control strategy for upright stance involves the task-specific coordination of multiple degrees of freedom. PMID:26879770

  15. STS payloads mission control study continuation phase A-1. Volume 2-C, task 3: Identification of joint activities and estimation of resources in preparation for joint flight operations

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Payload mission control concepts are developed for real time flight operations of STS. Flight planning, training, simulations, and other flight preparations are included. Payload activities for the preflight phase, activity sequences and organizational allocations, and traffic and experience factors to establish composite man-loading for joint STS payload activities are identified for flight operations from 1980 to 1985.

  16. Mechanics of Re-Torquing in Bolted Flange Connections

    NASA Technical Reports Server (NTRS)

    Gordon, Ali P.; Drilling Brian; Weichman, Kyle; Kammerer, Catherine; Baldwin, Frank

    2010-01-01

    It has been widely accepted that the phenomenon of time-dependent loosening of flange connections is a strong consequence of the viscous nature of the compression seal material. Characterizing the coupled interaction between gasket creep and elastic bolt stiffness has been useful in predicting conditions that facilitate leakage. Prior advances on this sub-class of bolted joints has lead to the development of (1) constitutive models for elastomerics, (2) initial tightening strategies, (3) etc. The effect of re-torque, which is a major consideration for typical bolted flange seals used on the Space Shuttle fleet, has not been fully characterized, however. The current study presents a systematic approach to characterizing bolted joint behavior as the consequence of sequentially applied torques. Based on exprimenta1 and numerical results, the optimal re-torquing parameters have been identified that allow for the negligible load loss after pre-load application

  17. Negative Optical Torque

    PubMed Central

    Chen, Jun; Ng, Jack; Ding, Kun; Fung, Kin Hung; Lin, Zhifang; Chan, C. T.

    2014-01-01

    Light carries angular momentum, and as such it can exert torques on material objects. Applications of these opto-mechanical effects were limited initially due to their smallness in magnitude, but later becomes powerful and versatile after the invention of laser. Novel and practical approaches for harvesting light for particle rotation have since been demonstrated, where the structure is always subjected to a positive optical torque along a certain axis if the incident angular momentum has a positive projection on the same axis. We report here an interesting phenomenon of “negative optical torque”, meaning that incoming photons carrying angular momentum rotate an object in the opposite sense. Surprisingly this can be realized quite straightforwardly in simple planar structures. Field retardation is a necessary condition and discrete rotational symmetry of material object plays an important role. The optimal conditions are explored and explained. PMID:25226863

  18. Activities of the US-Japan Safety Monitor Joint Working Group

    SciTech Connect

    Richard L. Savercool; Lee C. Cadwallader

    2004-09-01

    This paper documents the activities of the US-Japan exchange in the area of personnel safety at magnetic and laser fusion experiments. A near-miss event with a visiting scientist to the US in 1992 was the impetus for forming the Joint Working Group on Fusion Safety. This exchnge has been under way for over ten years and has provided many safety insights for both US and Japanese facility personnel at national institutes and at universities. The background and activities of the Joint Working Group are described, including the facilities that have been visited for safety walkthroughs, the participants from both countries, and the main safety issues examined during visits. Based on these visits, some operational safety ideas to enhance experiment safety are given. The near-term future plans of the Safety Monitor Joint Working group are also discussed.

  19. A Fluctuating Torque

    NASA Astrophysics Data System (ADS)

    Zamorano, Nelson; Gómez, Alfredo

    2013-04-01

    The existence of a fluctuating torque generates a wide variety of possible orbits. This situation contrasts with those examples where the torque vanishes and the angular momentum remains constant. Here we study a two dimensional example with a logarithmic effective potential V(x,y)= 12,,^2o,[ x^2 + (y/b)^2], with a small deviation from the axis symmetry given by the constant b with b < 1. Briefly, the effective potential models the gravitational force exerted by the N point particles on a test object. This potential is used to learn about the dynamics of galaxies and among other features, generates a fluctuating torque which is our main interest here. There is not an analytical solution for these two equations of motion. A simple numerical approach (provided) is required. Also, a change on the initial conditions may generate a different shape for the orbit. This apparently simple potential, represents a challenge for the students. We propose it as a good pedagogical tool for reviewing the main concepts of newtonian dynamics.

  20. A New Twist on Torque Labs

    ERIC Educational Resources Information Center

    Lane, W. Brian

    2014-01-01

    The traditional introductory-level meterstick-balancing lab assumes that students already know what torque is and that they readily identify it as a physical quantity of interest. We propose a modified version of this activity in which students qualitatively and quantitatively measure the amount of force required to keep the meterstick level. The…

  1. Changes in muscle and joint coordination in learning to direct forces.

    PubMed

    Hasson, Christopher J; Caldwell, Graham E; van Emmerik, Richard E A

    2008-08-01

    While it has been suggested that bi-articular muscles have a specialized role in directing external reaction forces, it is unclear how humans learn to coordinate mono- and bi-articular muscles to perform force-directing tasks. Participants were asked to direct pedal forces in a specified target direction during one-legged cycling. We expected that with practice, performance improvement would be associated with specific changes in joint torque patterns and mono- and bi-articular muscular coordination. Nine male participants practiced pedaling an ergometer with only their left leg, and were instructed to always direct their applied pedal force perpendicular to the crank arm (target direction) and to maintain a constant pedaling speed. After a single practice session, the mean error between the applied and target pedal force directions decreased significantly. This improved performance was accompanied by a significant decrease in the amount of ankle angular motion and a smaller increase in knee and hip angular motion. This coincided with a re-organization of lower extremity joint torques, with a decrease in ankle plantarflexor torque and an increase in knee and hip flexor torques. Changes were seen in both mono- and bi-articular muscle activity patterns. The mono-articular muscles exhibited greater alterations, and appeared to contribute to both mechanical work and force-directing. With practice, a loosening of the coupling between bi-articular thigh muscle activation and joint torque co-regulation was observed. The results demonstrated that participants were able to learn a complex and dynamic force-directing task by changing the direction of their applied pedal forces through re-organization of joint torque patterns and mono- and bi-articular muscle coordination. PMID:18405988

  2. Changes in Muscle and Joint Coordination in Learning to Direct Forces

    PubMed Central

    Hasson, Christopher J.; Caldwell, Graham E.; van Emmerik, Richard E.A.

    2008-01-01

    While it has been suggested that biarticular muscles have a specialized role in directing external reaction forces, it is unclear how humans learn to coordinate mono- and bi-articular muscles to perform force-directing tasks. Subjects were asked to direct pedal forces in a specified target direction during one-legged cycling. We expected that with practice, performance improvement would be associated with specific changes in joint torque patterns and mono- and bi-articular muscular coordination. Nine male subjects practiced pedaling an ergometer with only their left leg, and were instructed to always direct their applied pedal force perpendicular to the crank arm (target direction) and to maintain a constant pedaling speed. After a single practice session, the mean error between the applied and target pedal force directions decreased significantly. This improved performance was accompanied by a significant decrease in the amount of ankle angular motion and a smaller increase in knee and hip angular motion. This coincided with a re-organization of lower extremity joint torques, with a decrease in ankle plantarflexor torque and an increase in knee and hip flexor torques. Changes were seen in both mono- and bi-articular muscle activity patterns. The monoarticular muscles exhibited greater alterations, and appeared to contribute to both mechanical work and force directing. With practice, a loosening of the coupling between biarticular thigh muscle activation and joint torque co-regulation was observed. The results demonstrated that subjects were able to learn a complex and dynamic force-directing task by changing the direction of their applied pedal forces through re-organization of joint torque patterns and mono- and bi-articular muscle coordination. PMID:18405988

  3. Pacific Northwest USDA-ARS Jointed Goatgrass Research and Extension Activities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The USDA-ARS weed scientists have conducted research and extension activities on six research projects funded by the National Jointed Goatgrass Research Program (NJGGRP). This poster reviews the objectives and major research findings from these federally funded projects. Most of these projects wer...

  4. 77 FR 60746 - Proposed Information Collection (VA/DOD Joint Disability Evaluation Board Claim) Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-04

    ... 20420 or email to ] nancy.kessinger@va.gov . Please refer to ``OMB Control No. 2900-0704'' in any... AFFAIRS Proposed Information Collection (VA/DOD Joint Disability Evaluation Board Claim) Activity: Comment...: The Veterans Benefits Administration (VBA), Department of Veterans Affairs (VA), is announcing...

  5. In vitro activity of dalbavancin against biofilms of staphylococci isolated from prosthetic joint infections.

    PubMed

    Fernández, Javier; Greenwood-Quaintance, Kerryl E; Patel, Robin

    2016-08-01

    The in vitro activity of dalbavancin was tested against biofilms of 171 staphylococci associated with prosthetic joint infection. Dalbavancin minimum biofilm bactericidal concentration (MBBC) values were: MBBC50 for Staphylococcus aureus and Staphylococcus epidermidis, 1μg/mL; MBBC90 for S. aureus, 2μg/mL; MBBC90 for S. epidermidis, 4μg/mL. PMID:27241369

  6. Processes and Outcomes of Joint Activity with E-Books for Promoting Kindergarteners' Emergent Literacy

    ERIC Educational Resources Information Center

    Shamir, Adina

    2009-01-01

    This research investigated the effects of an educational electronic book (e-book) on low socioeconomic status (SES) kindergarteners' emergent literacy while focusing on the relationship between process and outcomes during joint learning. The sample (96 kindergarteners, aged five to six) was randomly assigned to experimental (e-book activation) and…

  7. 15 CFR 296.9 - Activities not permitted for joint ventures.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Activities not permitted for joint ventures. 296.9 Section 296.9 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE NIST EXTRAMURAL PROGRAMS...

  8. 15 CFR 296.9 - Activities not permitted for joint ventures.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false Activities not permitted for joint ventures. 296.9 Section 296.9 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE NIST EXTRAMURAL PROGRAMS...

  9. 15 CFR 296.9 - Activities not permitted for joint ventures.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 1 2012-01-01 2012-01-01 false Activities not permitted for joint ventures. 296.9 Section 296.9 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE NIST EXTRAMURAL PROGRAMS...

  10. 15 CFR 296.9 - Activities not permitted for joint ventures.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Activities not permitted for joint ventures. 296.9 Section 296.9 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign Trade NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, DEPARTMENT OF COMMERCE NIST EXTRAMURAL PROGRAMS...

  11. A Joint Learning Activity in Process Control and Distance Collaboration between Future Engineers and Technicians

    ERIC Educational Resources Information Center

    Deschênes, Jean-Sebastien; Barka, Noureddine; Michaud, Mario; Paradis, Denis; Brousseau, Jean

    2013-01-01

    A joint learning activity in process control is presented, in the context of a distance collaboration between engineering and technical-level students, in a similar fashion as current practices in the industry involving distance coordination and troubleshooting. The necessary infrastructure and the setup used are first detailed, followed by a…

  12. Relative contribution of contact and complement activation to inflammatory reactions in arthritic joints.

    PubMed Central

    Abbink, J J; Kamp, A M; Nuijens, J H; Erenberg, A J; Swaak, A J; Hack, C E

    1992-01-01

    Although both the complement and contact system are thought to contribute to the inflammatory reaction in arthritic joints, only activation of complement has so far been well established, whereas contact activation and its contribution to arthritis has not been systematically explored. Complement and contact activation were assessed in 71 patients with inflammatory arthropathies and 11 with osteoarthritis using sensitive assays for C3a, and C1-inhibitor (C1INH)-kallikrein and C1INH-factor XIIa complexes respectively. Increased plasma concentrations of kallikrein-and factor XIIa-C1INH complexes were found in two and seven of the 71 patients with inflammatory arthropathies, respectively, and in none of the patients with osteoarthritis. Increased synovial fluid concentrations of kallikrein and factor XIIa complexes occurred in 13 and 15 patients with inflammatory joint diseases respectively, and in two patients with osteoarthritis. Contact system parameters did not correlate with clinical symptoms, local activity, or neutrophil activation. In contrast, synovial fluid concentrations of C3a and C1INH-C1 complexes were increased in all patients and in 20 patients with inflammatory arthropathies respectively, and were higher in patients with a higher local activity score. Synovial fluid C3a correlated with parameters of neutrophil activation such as lactoferrin. Increased plasma concentrations of C3a and C1INH-C1 complexes occurred in 13 and 11 patients with inflammatory joint diseases, and in one and two patients with osteoarthritis respectively. Plasma concentrations of C3a correlated with the number of painful joints. Thus contact activation occurs only sporadically in patients with arthritis and contributes little if anything to the local inflammatory reaction and neutrophil activation. These latter events are significantly related to the extent of complement activation. PMID:1444625

  13. Neck rotation modulates flexion synergy torques, indicating an ipsilateral reticulospinal source for impairment in stroke

    PubMed Central

    Drogos, Justin; Carmona, Carolina; Keller, Thierry; Dewald, Julius P. A.

    2012-01-01

    The effect of reticular formation excitability on maximum voluntary torque (MVT) generation and associated muscle activation at the shoulder and elbow was investigated through natural elicitation (active head rotation) of the asymmetric tonic neck reflex (ATNR) in 26 individuals with stroke and 9 age-range-matched controls. Isometric MVT generation at the shoulder and elbow was quantified with the head rotated (face pointing) contralateral and ipsilateral to the paretic (stroke) and dominant (control) arm. Given the dominance of abnormal torque coupling of elbow flexion with shoulder abduction (flexion synergy) in stroke and well-developed animal models demonstrating a linkage between reticular formation and ipsilateral elbow flexors and shoulder abductors, we hypothesized that constituent torques of flexion synergy, specifically elbow flexion and shoulder abduction, would increase with contralateral head rotation. The findings of this investigation support this hypothesis. Increases in MVT for three of four flexion synergy constituents (elbow flexion, shoulder abduction, and shoulder external rotation) were observed during contralateral head rotation only in individuals with stroke. Electromyographic data of the associated muscle coactivations were nonsignificant but are presented for consideration in light of a likely underpowered statistical design for this specific variable. This study not only provides evidence for the reemergence of ATNR following stroke but also indicates a common neuroanatomical link, namely, an increased reliance on ipsilateral reticulospinal pathways, as the likely mechanism underlying the expression of both ATNR and flexion synergy that results in the loss of independent joint control. PMID:22956793

  14. Spin-torque generation in topological insulator based heterostructures

    NASA Astrophysics Data System (ADS)

    Fischer, Mark H.; Vaezi, Abolhassan; Manchon, Aurelien; Kim, Eun-Ah

    2016-03-01

    Heterostructures utilizing topological insulators exhibit a remarkable spin-torque efficiency. However, the exact origin of the strong torque, in particular whether it stems from the spin-momentum locking of the topological surface states or rather from spin-Hall physics of the topological-insulator bulk, remains unclear. Here, we explore a mechanism of spin-torque generation purely based on the topological surface states. We consider topological-insulator-based bilayers involving ferromagnetic metal (TI/FM) and magnetically doped topological insulators (TI/mdTI), respectively. By ascribing the key theoretical differences between the two setups to location and number of active surface states, we describe both setups within the same framework of spin diffusion of the nonequilibrium spin density of the topological surface states. For the TI/FM bilayer, we find large spin-torque efficiencies of roughly equal magnitude for both in-plane and out-of-plane spin torques. For the TI/mdTI bilayer, we elucidate the dominance of the spin-transfer-like torque. However, we cannot explain the orders of magnitude enhancement reported. Nevertheless, our model gives an intuitive picture of spin-torque generation in topological-insulator-based bilayers and provides theoretical constraints on spin-torque generation due to topological surface states.

  15. Kinematics of wrist joint flexion in overarm throws made by skilled subjects.

    PubMed

    Debicki, D B; Gribble, P L; Watts, S; Hore, J

    2004-02-01

    Previous studies of multijoint arm movements have shown that the CNS holds arm kinematics constant in different situations by predictively compensating for the effects of interaction torques. We determined whether this was also the case for wrist joint flexion in natural overarm throws performed by skilled subjects in 3D, a situation where large passive torques can occur at the wrist. Specifically, we investigated whether wrist flexion amplitudes are held constant in throws of different speeds. Joint rotations were recorded at 1,000 Hz with the search-coil technique. Contrary to a previous study on constrained 2D throwing, indirect evidence was found that in fast throws passive torques associated with forearm deceleration were exploited to increase wrist flexion velocity. This increase in wrist flexion velocity was associated with constant wrist flexion amplitudes at ball release (mean 27 degrees) for throws of different speeds. Furthermore, final wrist flexion positions after ball release were similar for a particular subject irrespective of the speed of the throw. This was associated in faster throws with increased magnitudes of wrist flexor and wrist extensor EMG activity which damped passive torques associated with forearm angular deceleration. It is concluded that wrist flexion in overarm throws of different speeds is produced by central signals which precisely control net joint torque by both exploiting and damping passive torques during different parts of the throw to keep wrist joint angular position parameters constant. As such the results show that control strategies for natural 3D throwing are different from those for constrained 2D throwing. PMID:14598003

  16. A Multiple Degree of Freedom Lower Extremity Isometric Device to Simultaneously Quantify Hip, Knee and Ankle Torques

    PubMed Central

    Sánchez, Natalia; Acosta, Ana Maria; Stienen, Arno H.A.

    2015-01-01

    Characterization of the joint torque coupling strategies used in the lower extremity to generate maximal and submaximal levels of torque at either the hip, knee or ankle is lacking. Currently, there are no available isometric devices that quantify all concurrent joint torques in the hip, knee and ankle of a single leg during maximum voluntary torque generation. Thus, joint-torque coupling strategies in the hip, knee and concurrent torques at ankle and/or coupling patterns at the hip and knee driven by the ankle have yet to be quantified. This manuscript describes the design, implementation and validation of a multiple degree of freedom, lower extremity isometric device (the MultiLEIT) that accurately quantifies simultaneous torques at the hip, knee and ankle. The system was mechanically validated and then implemented with two healthy control individuals and two post-stroke individuals to test usability and patient acceptance. Data indicated different joint torque coupling strategies used by both healthy individuals. In contrast, data showed the same torque coupling patterns in both post-stroke individuals, comparable to those described in the clinic. Successful implementation of the MultiLEIT can contribute to the understanding of the underlying mechanisms responsible for abnormal movement patterns and aid in the design of therapeutic interventions. PMID:25163064

  17. The Research and Training Activities for the Joint Institute for Aeronautics and Acoustics

    NASA Technical Reports Server (NTRS)

    Cantwell, Brian

    1995-01-01

    This proposal requests continued support for the program of activities to be undertaken by the Ames-Stanford Joint Institute for Aeronautics and Acoustics during the period 1 Oct. 1995 - 30 Sept. 1996. The emphasis in this program is on training and research in experimental and computational methods with application to aerodynamics, acoustics and the important interactions between them. The program comprises activities in active flow control, Large Eddy Simulation of jet noise, flap aerodynamics and acoustics and high lift modeling studies. During the proposed period there will be a continued emphasis on the interaction between NASA Ames, Stanford University and Industry, particularly in connection with the high lift activities.

  18. Aberrant Activation of TGF-β in Subchondral Bone at the Onset of Rheumatoid Arthritis Joint Destruction

    PubMed Central

    Xu, Xin; Zheng, Liwei; Bian, Qin; Xie, Liang; Liu, Wenlong; Zhen, Gehua; Crane, Janet L; Zhou, Xuedong; Cao, Xu

    2016-01-01

    Rheumatoid arthritis (RA) is an autoimmune disease that often leads to joint destruction. A myriad of drugs targeting the immune abnormalities and downstream inflammatory cascades have been developed, but the joint destruction is not effectively halted. Here we report that aberrant activation of TGF-β in the subchondral bone marrow by immune response increases osteoprogenitors and uncoupled bone resorption and formation in RA mouse/rat models. Importantly, either systemic or local blockade of TGF-β activity in the subchondral bone attenuated articular cartilage degeneration in RA. Moreover, conditional deletion of TGF-β receptor II (Tgfbr2) in nestin-positive cells also effectively halted progression of RA joint destruction. Our data demonstrate that aberrant activation of TGF-β in the subchondral bone is involved at the onset of RA joint cartilage degeneration. Thus, modulation of subchondral bone TGF-β activity could be a potential therapy for RA joint destruction. PMID:25967237

  19. Synovial fluid matrix metalloproteinase-2 and -9 activities in dogs suffering from joint disorders

    PubMed Central

    MURAKAMI, Kohei; MAEDA, Shingo; YONEZAWA, Tomohiro; MATSUKI, Naoaki

    2016-01-01

    The activity of matrix metalloproteinase (MMP)-2 and MMP-9 in synovial fluids (SF) sampled from dogs with joint disorders was investigated by gelatin zymography and densitometry. Pro-MMP-2 showed similar activity levels in dogs with idiopathic polyarthritis (IPA; n=17) or canine rheumatoid arthritis (cRA; n=4), and healthy controls (n=10). However, dogs with cranial cruciate ligament rupture (CCLR; n=5) presented significantly higher pro-MMP-2 activity than IPA and healthy dogs. Meanwhile, dogs with IPA exhibited significantly higher activity of pro- and active MMP-9 than other groups. Activity levels in pro- and active MMP-9 in cRA and CCLR dogs were not significantly different from those in healthy controls. Different patterns of MMP-2 and MMP-9 activity may reflect the differences in the underlying pathological processes. PMID:26902805

  20. Magnetic Coupling Delivers Increased Torque

    NASA Technical Reports Server (NTRS)

    Carter, Edward L.

    1989-01-01

    Fixed magnetic pins reduce reluctance of gap in magnetic coupling. Concentrate flux and increase torque transmitted. Coupling arranged as face or radial drive. Addition of flux pins to gap between magnetically coupled shafts in bioreactor experiment increases transferred torque by almost 50 percent.

  1. Torque control for electric motors

    NASA Technical Reports Server (NTRS)

    Bernard, C. A.

    1980-01-01

    Method for adjusting electric-motor torque output to accomodate various loads utilizes phase-lock loop to control relay connected to starting circuit. As load is imposed, motor slows down, and phase lock is lost. Phase-lock signal triggers relay to power starting coil and generate additional torque. Once phase lock is recoverd, relay restores starting circuit to its normal operating mode.

  2. Momentum Confinement at Low Torque

    SciTech Connect

    Solomon, W M; Burrell, K H; deGrassie, J S; Budny, R; Groebner, R J; Heidbrink, W W; Kinsey, J E; Kramer, G J; Makowski, M A; Mikkelsen, D; Nazikian, R; Petty, C C; Politzer, P A; Scott, S D; Van Zeeland, M A; Zarnstorff, M C

    2007-06-26

    Momentum confinement was investigated on DIII-D as a function of applied neutral beam torque at constant normalized {beta}{sub N}, by varying the mix of co (parallel to the plasma current) and counter neutral beams. Under balanced neutral beam injection (i.e. zero total torque to the plasma), the plasma maintains a significant rotation in the co-direction. This 'intrinsic' rotation can be modeled as being due to an offset in the applied torque (i.e. an 'anomalous torque'). This anomalous torque appears to have a magnitude comparable to one co-neutral beam source. The presence of such an anomalous torque source must be taken into account to obtain meaningful quantities describing momentum transport, such as the global momentum confinement time and local diffusivities. Studies of the mechanical angular momentum in ELMing H-mode plasmas with elevated q{sub min} show that the momentum confinement time improves as the torque is reduced. In hybrid plasmas, the opposite effect is observed, namely that momentum confinement improves at high torque/rotation. The relative importance of E x B shearing between the two is modeled using GLF23 and may suggest a possible explanation.

  3. Extension joints: a tool to infer the active stress field orientation (case study from southern Italy)

    NASA Astrophysics Data System (ADS)

    De Guidi, Giorgio; Caputo, Riccardo; Scudero, Salvatore; Perdicaro, Vincenzo

    2013-04-01

    An intense tectonic activity in eastern Sicily and southern Calabria is well documented by the differential uplift of Late Quaternary coastlines and by the record of the strong historical earthquakes. The extensional belt that crosses this area is dominated by a well established WNW-ESE-oriented extensional direction. However, this area is largely lacking of any structural analysis able to define the tectonics at a more local scale. In the attempt to fill this gap of knowledge, we carried out a systematic analysis of extension joint sets. In fact, the systematic field collection of these extensional features, coupled with an appropriate inversion technique, allows to determine the characteristic of the causative tectonic stress field. Joints are defined as outcrop-scale mechanical discontinuities showing no evidence of shear motion and being originated as purely extensional fractures. Such tectonic features are one of the most common deformational structures in every tectonic environment and particularly abundant in the study area. A particular arrangement of joints, called "fracture grid-lock system", and defined as an orthogonal joint system where mutual abutting and crosscutting relationships characterize two geologically coeval joint sets, allow to infer the direction and the magnitude of the tectonic stress field. We performed the analyses of joints only on Pleistocene deposits of Eastern Sicily and Southern Calabria. Moreover we investigated only calcarenite sediments and cemented deposits, avoiding claysh and loose matrix-supported clastic sediments where the deformation is generally accomodated in a distributed way through the relative motion between the single particles. In the selection of the sites, we also took into account the possibility to clearly observe the geometric relationships among the joints. For this reason we chose curvilinear road cuts or cliffs, wide coastal erosional surfaces and quarries. The numerical inversions show a similar stress

  4. The Spin Torque Lego - from spin torque nano-devices to advanced computing architectures

    NASA Astrophysics Data System (ADS)

    Grollier, Julie

    2013-03-01

    Spin transfer torque (STT), predicted in 1996, and first observed around 2000, brought spintronic devices to the realm of active elements. A whole class of new devices, based on the combined effects of STT for writing and Giant Magneto-Resistance or Tunnel Magneto-Resistance for reading has emerged. The second generation of MRAMs, based on spin torque writing : the STT-RAM, is under industrial development and should be out on the market in three years. But spin torque devices are not limited to binary memories. We will rapidly present how the spin torque effect also allows to implement non-linear nano-oscillators, spin-wave emitters, controlled stochastic devices and microwave nano-detectors. What is extremely interesting is that all these functionalities can be obtained using the same materials, the exact same stack, simply by changing the device geometry and its bias conditions. So these different devices can be seen as Lego bricks, each brick with its own functionality. During this talk, I will show how spin torque can be engineered to build new bricks, such as the Spintronic Memristor, an artificial magnetic nano-synapse. I will then give hints on how to assemble these bricks in order to build novel types of computing architectures, with a special focus on neuromorphic circuits. Financial support by the European Research Council Starting Grant NanoBrain (ERC 2010 Stg 259068) is acknowledged.

  5. Optimal placement of semi-active joints in large-space truss structures

    NASA Astrophysics Data System (ADS)

    Wirnitzer, Jan; Kistner, A.; Gaul, Lothar

    2002-06-01

    The low structural damping of large space structures and the stringent positioning requirements in missions demand effective vibration suppression. The semi-active approach at hand is based on friction damping due to interfacial slip in semi-active joints which can be controlled by varying the normal pressure in the contact area using a piezo-disc actuator. This paper focuses on the optimal placement of semi-active joints for vibration suppression. The proposed method uses optimality criteria for actuator and sensor locations based on eigenvalues of the controllability and observability gramians. It is stated as a nonlinear multicriteria optimization problem with discrete variables which is solved by a stochastic search algorithm. As final step in the design procedure, parameters of the local feedback controllers assigned to each adaptive joint are optimized with respect to transient response of the structure. The present method is applied to a 10-bay truss structure. Simulation runs of the controlled structure are used to verify the optimization results.

  6. Incidence of joint replacement among active component service members, U.S. Armed Forces, 2004-2014.

    PubMed

    Daniele, Denise O; Taubman, Stephen B; Clark, Leslie L

    2015-05-01

    In the U.S., joint replacements have become more common and the average age of individuals who undergo joint replacements has decreased. Joint replacements among active component service members increased 10.5% during 2004-2009, then 61.9% during 2009-2014. Knees and hips were the most frequently replaced joints among service members. During the surveillance period (and particularly after 2009), incidence rates increased in each age group of service members 30 years or older. Relative to their respective counterparts, rates of joint replacement overall--and of the hip and knee specifically--were higher among service members who were black, non-Hispanic; officers; and healthcare workers. One year after joint replacement, 18.2% had retired; 5.2% had been medically disqualified from service; 6.3% had otherwise left service; and 70.3% were still in service. By 2 years post-joint replacement, 30.2% had retired; 13.0% had been medically disqualified; 10.0% had otherwise left service; and 46.8% were still in service. Service members aged 30-44 years were the most likely to remain in service post-joint replacement. Given the increases in the frequency of joint replacement among younger service members, the number of service members who remain in service post-joint replacement may continue to increase. PMID:25996170

  7. Thermal Spin Transfer Torques

    NASA Astrophysics Data System (ADS)

    Bauer, Gerrit

    2009-03-01

    The coupling between spin and charge in electronic transport is studied in the field of spintronics. Heat currents are coupled to both charge and spin currents as well [1]. This extension of spintronics to what may be called ``spin caloritronics'' recently enjoys renewed attention [2]. The spin-transfer torque associated with electric currents can excite magnetizations in nanostructures, switching magnetic configuration in spin valves and move domain walls in magnetic wires when exceeding critical values of the order of 10^7Acm-2 [3]. Also heat currents transfer spin angular momentum [4], either intrinsically or via the thermoelectric generation of particle spin currents. We predict that temperature differences of the order of 100 K over typical metallic nanostructures cause effects equivalent to the critical charge current densities. In this talk I will give a brief review of various aspects of spin caloritronics with emphasis on thermal spin transfer torques. This work has been carried out in collaboration with Moosa Hatami, Qinfang Zhang, Paul Kelly, Hans Joakim Skadsem, Arne Brataas and Sadamichi Maekawa. [4pt] [1] M. Johnson and R.H. Silsbee, Phys. Rev. B 35, 4959 (1987).[0pt] [2] International Workshop on Spin Caloritronics, Lorentz Center of Leiden University, 9-13 February 2009, http://www.lorentzcenter.nl/lc/web/2009/323/info.php3?wsid=323[0pt] [3] D. C. Ralph and M. D. Stiles, J. Magn. Magn. Mater. 320, 1190 (2008).[0pt] [4] M. Hatami, G.E.W. Bauer, Q. Zhang, and P.J. Kelly, Phys. Rev. Lett. 99, 066603 (2007).

  8. Spinal Inflammation in the Absence of Sacroiliac Joint Inflammation on Magnetic Resonance Imaging in Patients With Active Nonradiographic Axial Spondyloarthritis

    PubMed Central

    van der Heijde, Désirée; Sieper, Joachim; Maksymowych, Walter P; Brown, Matthew A; Lambert, Robert G W; Rathmann, Suchitrita S; Pangan, Aileen L

    2014-01-01

    Objective To evaluate the presence of spinal inflammation with and without sacroiliac (SI) joint inflammation on magnetic resonance imaging (MRI) in patients with active nonradiographic axial spondyloarthritis (SpA), and to compare the disease characteristics of these subgroups. Methods ABILITY-1 is a multicenter, randomized, controlled trial of adalimumab versus placebo in patients with nonradiographic axial SpA classified using the Assessment of SpondyloArthritis international Society axial SpA criteria. Baseline MRIs were centrally scored independently by 2 readers using the Spondyloarthritis Research Consortium of Canada (SPARCC) method for the SI joints and the SPARCC 6–discovertebral unit method for the spine. Positive evidence of inflammation on MRI was defined as a SPARCC score of ≥2 for either the SI joints or the spine. Results Among patients with baseline SPARCC scores, 40% had an SI joint score of ≥2 and 52% had a spine score of ≥2. Forty-nine percent of patients with baseline SI joint scores of <2, and 58% of those with baseline SI joint scores of ≥2, had a spine score of ≥2. Comparison of baseline disease characteristics by baseline SI joint and spine scores showed that a greater proportion of patients in the subgroup with a baseline SPARCC score of ≥2 for both SI joints and spine were male, and patients with spine and SI joint scores of <2 were younger and had shorter symptom duration. SPARCC spine scores correlated with baseline symptom duration, and SI joint scores correlated negatively with the baseline Bath Ankylosing Spondylitis Disease Activity Index, but neither correlated with the baseline Ankylosing Spondylitis Disease Activity Score, total back pain, the patient's global assessment of disease activity, the Bath Ankylosing Spondylitis Functional Index, morning stiffness, nocturnal pain, or C-reactive protein level. Conclusion Assessment by experienced readers showed that spinal inflammation on MRI might be observed in half of

  9. Differential activation by cytokines of mitogen-activated protein kinases in bovine temporomandibular-joint disc cells.

    PubMed

    Landesberg, R; Takeuchi, E; Puzas, J E

    1999-01-01

    Temporomandibular disorders affect a significant proportion of the population. While their aetiology is not well defined, recent histological studies suggest that the majority are similar to the osteoarthritis seen in other joints. Inflammatory cytokines such as interleukin-1 and tumour necrosis factor-alpha appear to be important in the cascade of events leading to joint destruction in osteoarthritis. Here, cells from the disc of bovine temporomandibular joint were used to examine the response to various cytokines in vitro. Disc cells were stimulated with interleukin-1alpha, tumour necrosis factor-alpha, transforming growth factor-beta, platelet-derived growth factor, and basic fibroblast growth factor. Their effects were monitored by assessing the phosphorylation of selected signal-transduction intermediates using western blot. Mitogen-activated protein kinases (Erk 1, Erk 2) were rapidly phosphorylated by exposure to basic fibroblast growth factor, platelet-derived growth factor, and tumour necrosis factor-alpha, while interleukin-1alpha showed a weak response. Transforming growth factor-beta failed to activate these kinases. Examination of the effect of these cytokines on p38 (an intermediate in the stress-activated protein-kinase pathway) showed an increase in phosphorylated p38 when stimulated with tumour necrosis factor-alpha and interleukin-1alpha. The amounts of phosphorylated signal transducer and activator of transcription-3 did not significantly increase when the cells were exposed to any of the cytokines. PMID:10075149

  10. Estimation of Electrically-Evoked Knee Torque from Mechanomyography Using Support Vector Regression.

    PubMed

    Ibitoye, Morufu Olusola; Hamzaid, Nur Azah; Abdul Wahab, Ahmad Khairi; Hasnan, Nazirah; Olatunji, Sunday Olusanya; Davis, Glen M

    2016-01-01

    The difficulty of real-time muscle force or joint torque estimation during neuromuscular electrical stimulation (NMES) in physical therapy and exercise science has motivated recent research interest in torque estimation from other muscle characteristics. This study investigated the accuracy of a computational intelligence technique for estimating NMES-evoked knee extension torque based on the Mechanomyographic signals (MMG) of contracting muscles that were recorded from eight healthy males. Simulation of the knee torque was modelled via Support Vector Regression (SVR) due to its good generalization ability in related fields. Inputs to the proposed model were MMG amplitude characteristics, the level of electrical stimulation or contraction intensity, and knee angle. Gaussian kernel function, as well as its optimal parameters were identified with the best performance measure and were applied as the SVR kernel function to build an effective knee torque estimation model. To train and test the model, the data were partitioned into training (70%) and testing (30%) subsets, respectively. The SVR estimation accuracy, based on the coefficient of determination (R²) between the actual and the estimated torque values was up to 94% and 89% during the training and testing cases, with root mean square errors (RMSE) of 9.48 and 12.95, respectively. The knee torque estimations obtained using SVR modelling agreed well with the experimental data from an isokinetic dynamometer. These findings support the realization of a closed-loop NMES system for functional tasks using MMG as the feedback signal source and an SVR algorithm for joint torque estimation. PMID:27447638

  11. In-vitro and in-vivo imaging of MMP activity in cartilage and joint injury

    PubMed Central

    Fukui, Tomoaki; Tenborg, Elizabeth; Yik, Jasper H. N.; Haudenschild, Dominik R.

    2015-01-01

    Non-destructive detection of cartilage-degrading activities represents an advance in osteoarthritis (OA) research, with implications in studies of OA pathogenesis, progression, and intervention strategies. Matrix metalloproteinases (MMPs) are principal cartilage degrading enzymes that contribute to OA pathogenesis. MMPSense750 is an in-vivo fluorimetric imaging probe with the potential to continuously and non-invasively trace real-time MMP activities, but its use in OA-related research has not been reported. Our objective is to detect and characterize the early degradation activities shortly after cartilage or joint injury with MMPSense750. We determined the appropriate concentration, assay time, and linear range using various concentrations of recombinant MMPs as standards. We then quantified MMP activity from cartilage explants subjected to either mechanical injury or inflammatory cytokine treatment in-vitro. Finally, we performed invivo MMP imaging of a mouse model of post-traumatic OA. Our in-vitro results showed that the optimal assay time was highly dependent on the MMP enzyme. In cartilage explant culture media, mechanical impact or cytokine treatment increased MMP activity. Injured knees of mice showed significantly higher fluorescent signal than uninjured knees. We conclude that MMPSense750 detects human MMP activities and can be used for in-vitro study with cartilage, as well as in-vivo studies of knee injury, and can offering real-time insight into the degradative processes that occurring within the joint before structural changes become evident radiographically. PMID:25817731

  12. Influence of electrical stimulation on hip joint adductor muscle activity during maximum effort

    PubMed Central

    Nakano, Sota; Wada, Chikamune

    2016-01-01

    [Purpose] This study investigated whether hip adductor activity was influenced by electrical stimulation of the tensor fascia lata muscle. [Subjects and Methods] The subjects were 16 nondisabled males. Each subject was asked to adduct the hip joint with maximum effort. The electromyogram of the adductor longus was recorded under two experimental conditions, with and without electrical stimulation of the tensor fascia lata. [Results] In the presence of electrical stimulation, muscle activity decreased to 72.9% (57.8–89.3%) of that without stimulation. [Conclusion] These results suggested that inactivation of the adductor group was promoted by electrical stimulation of the tensor fascia lata. PMID:27313387

  13. The surface geometry of inherited joint and fracture trace patterns resulting from active and passive deformation

    NASA Technical Reports Server (NTRS)

    Podwysocki, M. H.; Gold, D. P.

    1974-01-01

    Hypothetical models are considered for detecting subsurface structure from the fracture or joint pattern, which may be influenced by the structure and propagated to the surface. Various patterns of an initially orthogonal fracture grid are modeled according to active and passive deformation mechanisms. In the active periclinal structure with a vertical axis, fracture frequency increased both over the dome and basin, and remained constant with decreasing depth to the structure. For passive periclinal features such as a reef or sand body, fracture frequency is determined by the arc of curvature and showed a reduction over the reefmound and increased over the basin.

  14. In vitro activity of ceftaroline against staphylococci from prosthetic joint infection.

    PubMed

    Park, Kyung-Hwa; Greenwood-Quaintance, Kerryl E; Patel, Robin

    2016-02-01

    We tested the in vitro activity of ceftaroline by Etest against staphylococci recovered from patients with prosthetic joint infection, including 97 Staphylococcus aureus isolates (36%, oxacillin resistant) and 74 Staphylococcus epidermidis isolates (74%, oxacillin resistant). Ceftaroline inhibited all staphylococci at ≤0.5 μg/mL. The ceftaroline MIC(90/50) values for methicillin-susceptible S. aureus, methicillin-susceptible S. epidermidis, methicillin-resistant S. aureus, and methicillin-resistant S. epidermidis were 0.19/0.125, 0.094/0.047, 0.5/0.38, and 0.38/0.19 μg/mL, respectively. Based on these in vitro findings, ceftaroline should be further evaluated as a potential therapeutic option for the treatment of prosthetic joint infection caused by methicillin-susceptible and methicillin-resistant S. aureus and S. epidermidis. PMID:26602948

  15. Plantar flexor moment arm and muscle volume predict torque-generating capacity in young men

    PubMed Central

    Baxter, Josh R.

    2013-01-01

    Muscle volume is known to correlate with maximal joint torque in humans, but the role of muscle moment arm in determining maximal torque is less clear. Moderate correlations have been reported between maximal isometric knee extensor torque and knee extensor moment arm, but no such observations have been made for the ankle joint. It has been suggested that smaller muscle moment arms may enhance force generation at high rates of joint rotation, but this has not yet been observed for ankle muscles in vivo. The purpose of the present study was to correlate plantar flexor moment arm and plantar flexor muscle volume with maximal plantar flexor torque measured at different rates of plantar flexion. Magnetic resonance imaging was used to quantify the plantar flexor moment arm and muscle volume of the posterior compartment in 20 healthy young men. Maximal plantar flexor torque was measured isometrically and at three plantar flexion speeds using an isokinetic dynamometer. Plantar flexor torque was significantly correlated with muscle volume (0.222 < R2 < 0.322) and with muscle moment arm at each speed (0.323 < R2 < 0.494). While muscle volume was strongly correlated with body mass and stature, moment arm was not. The slope of the torque-moment arm regression line decreased as the rate of joint rotation increased, indicating that subjects with small moment arms experienced smaller reductions in torque at high speeds. The findings of this study suggest that plantar flexor moment arm is a determinant of joint strength that is at least as important as muscle size. PMID:24371016

  16. Sports activity after total joint arthroplasty: recommendations for the counseling physician.

    PubMed

    Buza, John A; Fink, Leslie A; Levine, William N

    2013-02-01

    Sports activity after total joint arthroplasty (TJA) has become an increasingly important topic, as many younger patients seeking TJA have higher postoperative expectations with regard to return to athletic activity. Our current knowledge of this area is largely based on retrospective clinical studies and surveys of surgeon recommendations. The decision to participate in sports after TJA depends on the patient's general health, prior athletic experience, type of TJA, and desired sporting activity. Ultimately, patients should discuss these factors with their physician in order to make an educated decision regarding sports activity after TJA. This article summarizes the best available evidence to help guide physicians in their conversation with patients regarding safe and appropriate sports activity after TJA. PMID:23445855

  17. The Effect of Manipulating Subject Mass on Lower Extremity Torque Patterns During Locomotion

    NASA Technical Reports Server (NTRS)

    DeWitt, John K.; Cromwell, Ronita L.; Hagan, R. Donald

    2007-01-01

    During locomotion, humans adapt their motor patterns to maintain coordination despite changing conditions (Reisman et al., 2005). Bernstein (1967) proposed that in addition to the present state of a given joint, other factors, including limb inertia and velocity, must be taken into account to allow proper motion to occur. During locomotion with added mass counterbalanced using vertical suspension to maintain body weight, vertical ground reaction forces (GRF's) increase during walking but decrease during running, suggesting that adaptation may be velocity-specific (De Witt et al., 2006). It is not known, however, how lower extremity joint torques adapt to changes in inertial forces. The purpose of this investigation was to examine the effects of increasing body mass while maintaining body weight upon lower-limb joint torque during walking and running. We hypothesized that adaptations in joint torque patterns would occur with the addition of body mass.

  18. Plasma torque and nonambipolar transport

    SciTech Connect

    Boozer, Allen H.

    2009-05-15

    Poloidal symmetry breaking in toroidal plasmas causes a damping of poloidal rotation and toroidal symmetry breaking a damping of toroidal rotation. These torques are transmitted by the magnetic field to the outside world. An upper limit exists on the torque that can be transmitted by magnetic asymmetries. This limit is enforced by shielding asymmetries from the plasma, which can be an important effect for toroidal asymmetries. The torque interaction of plasmas with magnetic fields can be either through an anisotropic pressure or by the drive for magnetic islands. The physics of both types of interactions are considered and paradoxical effects are clarified.

  19. Simulation of human gait using computed torque control.

    PubMed

    Unver, N F; Tümer, S T; Ozgören, M K

    2000-01-01

    This paper presents a method for the mathematical modeling of both the single and double support phases of the human gait. The governing equations are obtained by considering the linkage model to be in a floating state and the foot-ground interaction is imposed in the form of geometric constraints. Two stages for the single support phase and one stage for the double support phase are considered, each described by a different foot-ground constraint. Feedback controller functioning according to the computed torque control method is used to achieve the normal gait described by the hip and ankle trajectories. Weighted least square optimization is used to solve the redundancy of control torques during the double support phase. The geometric simulation indicates that the imposed trajectories can be realized by the proposed model with some deviations in joint motions. The control strategy is tested by artificially perturbing the trajectories. The corrective actions are able to resume the desired pattern within half cycle, but with control torque magnitudes considerably away from reasonable limits. This is attributed to the insufficiency of the planar kinematic model and the assumption that the joint torques are unbounded. PMID:10942991

  20. In-vitro and in-vivo imaging of MMP activity in cartilage and joint injury

    SciTech Connect

    Fukui, Tomoaki; Tenborg, Elizabeth; Yik, Jasper H.N.; Haudenschild, Dominik R.

    2015-05-08

    Non-destructive detection of cartilage-degrading activities represents an advance in osteoarthritis (OA) research, with implications in studies of OA pathogenesis, progression, and intervention strategies. Matrix metalloproteinases (MMPs) are principal cartilage degrading enzymes that contribute to OA pathogenesis. MMPSense750 is an in-vivo fluorimetric imaging probe with the potential to continuously and non-invasively trace real-time MMP activities, but its use in OA-related research has not been reported. Our objective is to detect and characterize the early degradation activities shortly after cartilage or joint injury with MMPSense750. We determined the appropriate concentration, assay time, and linear range using various concentrations of recombinant MMPs as standards. We then quantified MMP activity from cartilage explants subjected to either mechanical injury or inflammatory cytokine treatment in-vitro. Finally, we performed in-vivo MMP imaging of a mouse model of post-traumatic OA. Our in-vitro results showed that the optimal assay time was highly dependent on the MMP enzyme. In cartilage explant culture media, mechanical impact or cytokine treatment increased MMP activity. Injured knees of mice showed significantly higher fluorescent signal than uninjured knees. We conclude that MMPSense750 detects human MMP activities and can be used for in-vitro study with cartilage, as well as in-vivo studies of knee injury, and can offering real-time insight into the degradative processes that occurring within the joint before structural changes become evident radiographically. - Highlights: • MMPSense750 is near-infrared fluorescent probe which can detect MMP activity. • MMPSense750 can detect human MMP-3, -9, and -13. • The reaction kinetics with MMPSense750 were different for the three MMPs. • MMPSense750 can visualized real time MMP activity in mouse injured knees. • MMPSense750 is convenient tool to evaluate real-time MMP activity non-invasively.

  1. Structural health monitoring of multi-spot welded joints using a lead zirconate titanate based active sensing approach

    NASA Astrophysics Data System (ADS)

    Yao, Ping; Kong, Qingzhao; Xu, Kai; Jiang, Tianyong; Huo, Lin-sheng; Song, Gangbing

    2016-01-01

    Failures of spot welded joints directly reduce the load capacity of adjacent structures. Due to their complexity and invisibility, real-time health monitoring of spot welded joints is still a challenge. In this paper, a lead zirconate titanate (PZT) based active sensing approach was proposed to monitor the structural health of multi-spot welded joints in real time. In the active sensing approach, one PZT transducer was used as an actuator to generate a guided stress wave, while another one, as a sensor, detected the wave response. Failure of a spot welded joint reduces the stress wave paths and attenuates the wave propagation energy from the actuator to the sensor. A total of four specimens made of dual phase steel with spot welds, including two specimens with 20 mm intervals of spot welded joints and two with 25 mm intervals, were designed and fabricated for this research. Under tensile tests, the spot welded joints successively failed, resulting in the PZT sensor reporting decreased received energy. The energy attenuations due to the failures of joints were clearly observed by the PZT sensor signal in both the time domain and frequency domain. In addition, a wavelet packet-based spot-weld failure indicator was developed to quantitatively evaluate the failure condition corresponding to the number of failed joints.

  2. The Research and Training Activities for the Joint Institute for Aeronautics and Acoustics

    NASA Technical Reports Server (NTRS)

    Cantwell, Brian

    1996-01-01

    This proposal requests continued support for the program of activities to be undertaken by the Ames-Stanford Joint Institute for Aeronautics and Acoustics during the one-year period October 1, 1996 to September 30, 1997. The emphasis in this program is on training and research in experimental and computational methods with application to aerodynamics, acoustics and the important interactions between them. The program comprises activities in active flow control, Large Eddy Simulation of jet noise, flap aerodynamics and acoustics, high lift modeling studies and luminescent paint applications. During the proposed period there will be a continued emphasis on the interaction between NASA Ames, Stanford University and Industry, particularly in connection with the noise and high lift activities. The program will be conducted within the general framework of the Memorandum of Understanding (1976) establishing the Institute, as updated in 1993. As outlined in the agreement, the purposes of the institute include the following: To conduct basic and applied research. To promote joint endeavors between Center scientists and those in the academic community To provide training to graduate students in specialized areas of aeronautics and acoustics through participation in the research programs of the Institute. To provide opportunities for Post-Doctoral Fellows to collaborate in research programs of the Institute. To disseminate information about important aeronautical topics and to enable scientists and engineers of the Center to stay abreast of new advances through symposia, seminars and publications.

  3. The Research and Training Activities for the Joint Institute for Aeronautics and Acoustics

    NASA Technical Reports Server (NTRS)

    Cantwell, Brian

    1997-01-01

    This proposal requests continued support for the program of activities to be undertaken by the Ames-Stanford Joint Institute for Aeronautics and Acoustics during the one-year period October 1, 1997 to September 30, 1998. The emphasis in this program is on training and research in experimental and computational methods with application to aerodynamics, acoustics and the important interactions between them. The program comprises activities in active flow control, Large Eddy Simulation of jet noise, flap aerodynamics and acoustics, high lift modeling studies and luminescent paint applications. During the proposed period there will be a continued emphasis on the interaction between NASA Ames, Stanford University and Industry, particularly in connection with the noise and high lift activities. The program will be conducted within the general framework of the Memorandum of Understanding (1976) establishing the Institute, as updated in 1993. As outlined in the agreement, the purposes of the Institute include the following: (1) To conduct basic and applied research; (2) to promote joint endeavors between Center scientists and those in the academic community; (3) to provide training to graduate students in specialized areas of aeronautics and acoustics through participation in the research programs of the Institute; (4) to provide opportunities for Post-Doctoral Fellows to collaborate in research programs of the Institute; and (5) to disseminate information about important aeronautical topics and to enable scientists and engineers of the Center to stay abreast of new advances through symposia, seminars and publications.

  4. Imaging the magmatic system of Newberry Volcano using Joint active source and teleseismic tomography

    NASA Astrophysics Data System (ADS)

    Heath, Benjamin A.; Hooft, Emilie E. E.; Toomey, Douglas R.; Bezada, Maximiliano J.

    2015-12-01

    In this paper, we combine active and passive source P wave seismic data to tomographically image the magmatic system beneath Newberry Volcano, located east of the Cascade arc. By using both travel times from local active sources and delay times from teleseismic earthquakes recorded on closely spaced seismometers (300-800 m), we significantly improve recovery of upper crustal velocity structure (<10 km depth). The tomographic model reveals a low-velocity feature between 3 and 5 km depth that lies beneath the caldera, consistent with a magma body. In contrast to earlier tomographic studies, where elevated temperatures were sufficient to explain the recovered low velocities, the larger amplitude low-velocity anomalies in our joint tomography model require low degrees of partial melt (˜10%), and a minimum melt volume of ˜2.5 km3. Furthermore, synthetic tests suggest that even greater magnitude low-velocity anomalies, and by inference larger volumes of magma (up to 8 km3), are needed to explain the observed waveform variability. The lateral extent and shape of the inferred magma body indicates that the extensional tectonic regime at Newberry influences the emplacement of magmatic intrusions. Our study shows that jointly inverting active source and passive source seismic data improves tomographic imaging of the shallow crustal seismic structure of volcanic systems and that active source experiments would benefit from longer deployment times to also record teleseismic sources.

  5. Deformable micro torque swimmer

    NASA Astrophysics Data System (ADS)

    Ishikawa, Takuji; Tanaka, Tomoyuki; Omori, Toshihiro; Imai, Yohsuke

    2015-11-01

    We investigated the deformation of a ciliate swimming freely in a fluid otherwise at rest. The cell body was modeled as a capsule with a hyper elastic membrane enclosing Newtonian fluid. Thrust forces due to the ciliary beat were modeled as torques distributed above the cell body. Effects of the membrane elasticity, the aspect ratio of cell's reference shape and the density difference between the cell and the surrounding fluid were investigated. The results showed that the cell deformed like heart shape when Capillary number (Ca) was sufficiently large, and the swimming velocity decreased as Ca was increased. The gravity effect on the membrane tension suggested that the upwards and downwards swimming velocities of Paramecium might be reglated by the calcium ion channels distributed locally around the anterior end. Moreover, the gravity induced deformation made a cell directed vertically downwards, which resulted in a positive geotaxis like behavior with physical origin. These results are important to understand physiology of ciliate's biological responses to mechanical stimuli.

  6. Quick torque coupling

    DOEpatents

    Luft, Peter A.

    2009-05-12

    A coupling for mechanically connecting modular tubular struts of a positioning apparatus or space frame, comprising a pair of toothed rings (10, 12) attached to separate strut members (16), the teeth (18, 20) of the primary rings (10, 12) mechanically interlocking in both an axial and circumferential manner, and a third part comprising a sliding, toothed collar (14) the teeth (22) of which interlock the teeth (18, 20) of the primary rings (10, 12), preventing them from disengaging, and completely locking the assembly together. A secondary mechanism provides a nesting force for the collar, and/or retains it. The coupling is self-contained and requires no external tools for installation, and can be assembled with gloved hands in demanding environments. No gauging or measured torque is required for assembly. The assembly can easily be visually inspected to determine a "go" or "no-go" status. The coupling is compact and relatively light-weight. Because of it's triply interlocking teeth, the connection is rigid. The connection does not primarily rely on clamps, springs or friction based fasteners, and is therefore reliable in fail-safe applications.

  7. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine torque. 27.361 Section 27.361... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For turbine engines, the limit torque may not be less than the highest of— (1) The mean torque for...

  8. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine torque. 27.361 Section 27.361... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For turbine engines, the limit torque may not be less than the highest of— (1) The mean torque for...

  9. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Engine torque. 27.361 Section 27.361... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For turbine engines, the limit torque may not be less than the highest of— (1) The mean torque for...

  10. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine torque. 27.361 Section 27.361... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For turbine engines, the limit torque may not be less than the highest of— (1) The mean torque for...

  11. 40 CFR 1065.310 - Torque calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Torque calibration. 1065.310 Section... Conditions § 1065.310 Torque calibration. (a) Scope and frequency. Calibrate all torque-measurement systems including dynamometer torque measurement transducers and systems upon initial installation and after...

  12. 40 CFR 1065.310 - Torque calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Torque calibration. 1065.310 Section... Conditions § 1065.310 Torque calibration. (a) Scope and frequency. Calibrate all torque-measurement systems including dynamometer torque measurement transducers and systems upon initial installation and after...

  13. 14 CFR 27.361 - Engine torque.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 27.361 Section 27.361... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For turbine engines, the limit torque may not be less than the highest of— (1) The mean torque for...

  14. Strategy of arm movement control is determined by minimization of neural effort for joint coordination.

    PubMed

    Dounskaia, Natalia; Shimansky, Yury

    2016-06-01

    Optimality criteria underlying organization of arm movements are often validated by testing their ability to adequately predict hand trajectories. However, kinematic redundancy of the arm allows production of the same hand trajectory through different joint coordination patterns. We therefore consider movement optimality at the level of joint coordination patterns. A review of studies of multi-joint movement control suggests that a 'trailing' pattern of joint control is consistently observed during which a single ('leading') joint is rotated actively and interaction torque produced by this joint is the primary contributor to the motion of the other ('trailing') joints. A tendency to use the trailing pattern whenever the kinematic redundancy is sufficient and increased utilization of this pattern during skillful movements suggests optimality of the trailing pattern. The goal of this study is to determine the cost function minimization of which predicts the trailing pattern. We show that extensive experimental testing of many known cost functions cannot successfully explain optimality of the trailing pattern. We therefore propose a novel cost function that represents neural effort for joint coordination. That effort is quantified as the cost of neural information processing required for joint coordination. We show that a tendency to reduce this 'neurocomputational' cost predicts the trailing pattern and that the theoretically developed predictions fully agree with the experimental findings on control of multi-joint movements. Implications for future research of the suggested interpretation of the trailing joint control pattern and the theory of joint coordination underlying it are discussed. PMID:26983620

  15. Muscular Activation During Plyometric Exercises in 90° of Glenohumeral Joint Abduction

    PubMed Central

    Ellenbecker, Todd S.; Sueyoshi, Tetsuro; Bailie, David S.

    2015-01-01

    Background: Plyometric exercises are frequently used to increase posterior rotator cuff and periscapular muscle strength and simulate demands and positional stresses in overhead athletes. The purpose of this study was to provide descriptive data on posterior rotator cuff and scapular muscle activation during upper extremity plyometric exercises in 90° of glenohumeral joint abduction. Hypothesis: Levels of muscular activity in the posterior rotator cuff and scapular stabilizers will be high during plyometric shoulder exercises similar to previously reported electromyographic (EMG) levels of shoulder rehabilitation exercises. Study Design: Descriptive laboratory study. Methods: Twenty healthy subjects were tested using surface EMG during the performance of 2 plyometric shoulder exercises: prone external rotation (PERP) and reverse catch external rotation (RCP) using a handheld medicine ball. Electrode application included the upper and lower trapezius (UT and LT, respectively), serratus anterior (SA), infraspinatus (IN), and the middle and posterior deltoid (MD and PD, respectively) muscles. A 10-second interval of repetitive plyometric exercise (PERP) and 3 repetitions of RCP were sampled. Peak and average normalized EMG data were generated. Results: Normalized peak and average IN activity ranged between 73% and 102% and between 28% and 52% during the plyometric exercises, respectively, with peak and average LT activity measured between 79% and 131% and between 31% and 61%. SA activity ranged between 76% and 86% for peak and between 35% and 37% for average activity. Muscular activity levels in the MD and PD ranged between 49% and 72% and between 12% and 33% for peak and average, respectively. Conclusion: Moderate to high levels of muscular activity were measured in the rotator cuff and scapular stabilizers during these plyometric exercises with the glenohumeral joint abducted 90°. PMID:25553216

  16. Impact of decline-board squat exercises and knee joint angles on the muscle activity of the lower limbs

    PubMed Central

    Lee, Daehee; Lee, Sangyong; Park, Jungseo

    2015-01-01

    [Purpose] This study aims to investigate how squat exercises on a decline board and how the knee joint angles affect the muscle activity of the lower limbs. [Subjects] The subjects were 26 normal adults. [Methods] A Tumble Forms wedge device was used as the decline board, and the knee joint angles were measured with a goniometer. To examine the muscle activity of the biceps femoris, rectus femoris, gastrocnemius lateralis, and tibialis anterior of the lower limbs, a comparison analysis with electromyography was conducted. [Results] The muscle activity of the biceps femoris, rectus femoris, gastrocnemius lateralis, and tibialis anterior increased with increased knee joint angles, both for squat exercises on the decline board and on a flat floor. When the knee joint angle was 45°, 60°, and 90°, the muscle activity of the rectus femoris was significantly higher and that of the tibialis anterior was significantly lower during squat exercises on the decline board than on the flat floor. When the knee joint angle was 90°, the muscle activity of the gastrocnemius lateralis was significantly lower. [Conclusion] Squat exercises on a decline board are an effective intervention to increase the muscle activity of the rectus femoris with increased knee joint angles. PMID:26357447

  17. Pressurized fluid torque driver control and method

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1994-01-01

    Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.

  18. Ruminant methane reduction through livestock development in Tanzania. Final report for US Department of Energy and US Initiative on Joint Implementation--Activities Implemented Jointly

    SciTech Connect

    Livingston, Roderick

    1999-07-01

    This project was designed to help develop the US Initiative on Joint Implementation activities in Eastern Africa. It has been communicated in meetings with representatives from the Ministry of Environment of Tanzania and the consultant group that developed Tanzania's National Climate Change Action Plan, the Centre for Energy, Environment, Science and Technology, that this project fits very well with the developmental and environmental goals of the Government of Tanzania. The goal of the Activities Implemented Jointly ruminant livestock project is to reduce ruminant methane emissions in Eastern Africa. The project plans a sustainable cattle multiplication unit (CMU) at Mabuki Ranch in the Mwanza Region of Tanzania. This CMU will focus on raising genetically improved animals to be purchased by farmers, developmental organizations, and other CMUs in Tanzania. Through the purchase of these animals farmers will raise their income generation potential and reduce ruminant methane emissions.

  19. Kinematic Characteristics of the Tibiofemoral Joint during a Step-up Activity

    PubMed Central

    Li, Jing-Sheng; Hosseini, Ali; Cancre, Lucile; Ryan, Nolan; Rubash, Harry E; Li, Guoan

    2013-01-01

    The step-up activity (stair-ascending) is an important daily function of the knee. This study aimed to investigate the articular cartilage contact kinematics on both tibial and femoral cartilage surfaces and describe the femoral condylar motion using the transepicondylar axis (TEA) and the geometric center axis (GCA) during a step-up activity. Twenty-one healthy subjects were included and their knee joint models were reconstructed using MR images. A single-stair step-up activity was imaged using a dual-fluoroscopic imaging system. Three-dimensional knee joint contact points were determined and projected onto the tibial plateau and femoral condyle surfaces. The contact points on the medial and lateral tibial plateau moved anteriorly (by 13.5 ± 3.2 and 10.7 ± 5.0 mm, respectively, p>0.05) with knee extension. The contact points on the medial and lateral femoral condyle moved from the posterior to the anterior portion (by 32.2 ± 4.9 mm and 25.5 ± 4.2 mm, respectively, p<0.05) and were located on the inner half of the femoral cartilage throughout the activity. The data on articular contact kinematics and the femoral condylar motion described using the TEA and GCA indicated that the medial and lateral compartments had similar motion patterns during the step-up activity. The knee does not demonstrate a medial-pivoting motion character during the step-up activity. The data may provide insight to contemporary TKA development. PMID:23541765

  20. Torque Measurement of 3-DOF Haptic Master Operated by Controllable Electrorheological Fluid

    NASA Astrophysics Data System (ADS)

    Oh, Jong-Seok; Choi, Seung-Bok; Lee, Yang-Sub

    2015-02-01

    This work presents a torque measurement method of 3-degree-of-freedom (3-DOF) haptic master featuring controllable electrorheological (ER) fluid. In order to reflect the sense of an organ for a surgeon, the ER haptic master which can generate the repulsive torque of an organ is utilized as a remote controller for a surgery robot. Since accurate representation of organ feeling is essential for the success of the robot-assisted surgery, it is indispensable to develop a proper torque measurement method of 3-DOF ER haptic master. After describing the structural configuration of the haptic master, the torque models of ER spherical joint are mathematically derived based on the Bingham model of ER fluid. A new type of haptic device which has pitching, rolling, and yawing motions is then designed and manufactured using a spherical joint mechanism. Subsequently, the field-dependent parameters of the Bingham model are identified and generating repulsive torque according to applied electric field is measured. In addition, in order to verify the effectiveness of the proposed torque model, a comparative work between simulated and measured torques is undertaken.

  1. Comparison of facet joint activity on 99mTc-MDP SPECT/CT with facet joint signal change on MRI with fat suppression

    PubMed Central

    Lehman, Vance T.; Murphy, Robert C.; Schenck, Louis A.; Carter, Rickey E.; Johnson, Geoffrey B.; Kotsenas, Amy L.; Morris, Jonathan M.; Nathan, Mark A.; Wald, John T.; Maus, Timothy P.

    2016-01-01

    PURPOSE We compared signal change on magnetic resonance imaging (MRI) with fat suppression and bone scan activity of lumbar facet joints to determine if these two imaging findings are correlated. METHODS We retrospectively identified all patients who underwent imaging of the lumbar spine for pain evaluation using both technetium-99m methylene disphosphonate single-photon emission computed tomography/computed tomography (99mTc-MDP SPECT/CT) and MRI with at least one fat-suppressed T2- or T1-weighted sequence with gadolinium enhancement within a 180-day interval, at our institution between 1 January 2008 and 19 February 2013. Facet joint activity on 99mTc-MDP SPECT/CT and peri-facet signal change on MRI were rated as normal or increased. Agreement between the two examination types were determined with the κ and prevalence-adjusted bias-adjusted κ (PABAK) statistics. RESULTS This study included 60 patients (28 male, 47%), with a mean age of 49±19.7 years (range, 12–93 years). The κ value indicated no agreement between 99mTc-MDP SPECT/CT and MRI (κ=−0.026; 95% confidence interval: −0.051, 0.000). The PABAK values were fair to high at each spinal level, which suggests that relatively low disease prevalence lowered the κ values. Together, the κ and PABAK values indicate that there is some degree of intermodality agreement, but that it is not consistent. CONCLUSION Overall, facet joint signal change on fat-suppressed MRI did not always correlate with increased 99mTc-MDP SPECT/CT activity. MRI and 99mTc-MDP SPECT/CT for facet joint evaluation should not be considered interchangeable examinations in clinical practice or research. PMID:27035592

  2. Using min-max of torque to resolve redundancy for a mobile manipulator

    SciTech Connect

    Reister, D.B.

    1993-11-01

    We have considered the problem of determining the time trajectories of the joint variables of a mobile manipulator with many redundant degrees of freedom that will minimize the maximum value of the torque during a large scale motion by the manipulator. To create a well defined problem, we will divide the problem into two components: path planner and surveyor. The path planner will choose a path (between two points in Cartesian space) that will minimize the maximum value of the torque along the path. The input to the path planner is a network of path segments with the maximum value of the torque on each segment. The surveyor will find the points in joint space that are local minimums for the maximum value of the torque at each Cartesian position and define the network of path segments. In this paper, our focus will be on the surveyor and not on the path planner. Our min-max problem has an extra constraint on the joint variables. We seek a min-max at each Cartesian position rather than a global min-max. We have used the Kuhn-Tucker conditions to derive necessary conditions for the solution of our min-max problem. We find that the necessary conditions require that at one or more of the joints the magnitude of the normalized torques will be equal to the min-max value. We have explored the torque surfaces for two mobile manipulators: a planar manipulator and the CESARm. The CESARm is a manipulator with three joint angles controlling the height of the arm. The paths with three equal torques have low values for the torque but they only cover part of the workspace and do not join together. Paths with two equal torques cover the workspace and bridge between the disjoint path segments. We have evaluated the necessary conditions for both the paths with three equal torques and the paths with two equal torques. In most cases, the paths satisfy the necessary conditions.

  3. The effect of load on torques in point-to-point arm movements: a 3D model.

    PubMed

    Tibold, Robert; Laczko, Jozsef

    2012-01-01

    A dynamic, 3-dimensional model was developed to simulate slightly restricted (pronation-supination was not allowed) point-to-point movements of the upper limb under different external loads, which were modeled using 3 objects of distinct masses held in the hand. The model considered structural and biomechanical properties of the arm and measured coordinates of joint positions. The model predicted muscle torques generated by muscles and needed to produce the measured rotations in the shoulder and elbow joints. The effect of different object masses on torque profiles, magnitudes, and directions were studied. Correlation analysis has shown that torque profiles in the shoulder and elbow joints are load invariant. The shape of the torque magnitude-time curve is load invariant but it is scaled with the mass of the load. Objects with larger masses are associated with a lower deflection of the elbow torque with respect to the sagittal plane. Torque direction-time curve is load invariant scaled with the mass of the load. The authors propose that the load invariance of the torque magnitude-time curve and torque direction-time curve holds for object transporting arm movements not restricted to a plane. PMID:22938084

  4. The effect of co-stabilizer muscle activation on knee joint position sense: a single group pre-post test

    PubMed Central

    Nam, Yeongyo; Lee, Ho Jun; Choi, Myongryol; Chung, Sangmi; Park, Junhyung; Yu, Jaeho

    2016-01-01

    [Purpose] The purpose of this study was to investigate the effect of co-stabilizer muscle activation on knee joint position sense. [Subjects and Methods] This study was a pre-post, single-blinded randomly controlled trial (angle sequence randomly selected) design. Seven healthy adults with no orthopaedic or neurological problems participated in this study. Knee joint position sense was measured by a target matching test at target angles of 30°, 45° and 80° of knee flexion a using digital inclinometer under two conditions: erect sitting, which is known to highly activate co-stabilizer muscle and slump sitting, which is known to little activate the co-stabilizer muscle. [Results] A significant difference in joint position matching error at the knee flexion angle of 45° was founded between two conditions erect sitting: (3.83 ± 1.47) and slump sitting: (1.00 ± 0.63). There were no significant differences in joint position matching error at the other target angles. [Conclusion] Knee joint position sense at 45° is likely to be affected by activation of co-stabilizer muscle, and this value is suitable for facilitation of joint position sense with skilled movement. PMID:27512279

  5. Habitual hip joint activity level of the penned EMU (Dromaius novaehollandie).

    PubMed

    Troy, Karen L; Lundberg, Hannah J; Conzemius, Michael G; Brown, Thomas D

    2007-01-01

    Orthopaedic management of femoral head osteonecrosis remains problematic, partly because of inability to systematically compare treatments in an animal model whose natural history parallels the human in terms of progression to femoral head collapse. Recently, it was determined that collapse could be consistently achieved for cryogenically induced osteonecrosis in the emu. Toward delineating the comparative hip joint biomechanics of emus versus humans, for purposes of establishing the emu as a model for human femoral head osteonecrosis, habitual hip joint activity level was quantified for a group of seven healthy adult emus housed in an outdoor research pen typical of those used in emu farming operations. The daily number of steps taken, and the time spent with the hips loaded (standing, or squatting/sitting) versus unloaded (recumbent), were quantified from 24-hour videotape recordings, analyzed by four independent observers. The average number of steps taken per day was 9563, which extrapolates to 1.8 million hip loadings per year, a value that falls in the same general range as seen in normal adult humans. On average, the emus spent 4:05 hours per day idly standing, 2:12 hours squatting/sitting, and 10:44 hours recumbent; they underwent an average of 37 transitions per day between the respective posture/activity states. PMID:17907425

  6. Some new evidence on human joint lubrication.

    PubMed Central

    Unsworth, A; Dowson, D; Wright, V

    1975-01-01

    Theoretical consideration has been given to the use of pendulum machines which are used to examine the frictional properties of human joints by incorporating them as fulcra. As a result, a new type of pendulum machine has been built which incorporates the facility to apply sudden loads to the joint on starting the swinging motion, and also the ability to measure directly the frictional torque experienced by the joint. The results obtained from natural hip joints indicate the presence of squeeze film lubrication under conditions of sudden loading of a joint. In addition, a self-generated fluid film process was observed at low loads while at higher loads boundary lubrication appeared to be important. These results have been used to describe the lubrication regimens occurring in a normal activity such as walking. A single experiment carried out on a hip from a patient suffering from severe rheumatoid arthritis has also been reported and the frictional resistance was seen to be increased fifteenfold compared to a normal hip. Images PMID:1190847

  7. How do people with chronically painful joint hypermobility syndrome make decisions about activity?

    PubMed Central

    Schmidt, Anne; Corcoran, Kelley; Grahame, Rodney

    2015-01-01

    Background: The model of activity avoidance prompted by fear of increased pain and/or harm dominates understanding and research into activity limitation in chronic pain. Yet, the accounts of people with chronic pain on decisions about activity limitation are rarely heard beyond the confines of fear and avoidance questionnaires. Methods: We used semi-structured interviews to explore the decisions of 11 women attending a pain management clinic with chronically painful Joint Hypermobility Syndrome (JHS). Results: Six themes emerged from Interpretative Phenomenological Analysis: the overall aim of keeping pain to a manageable level, considering whether the planned activity was worth it and, running through all judgements, the influence of pain intensity. The decision was tipped towards avoidance by unpredictability of pain and by high emotional cost and towards going ahead with the activity by the wish to exert control and by low emotional cost. Many accounts described a specifiable cost–benefit analysis of individual decisions, weighing the importance of each activity against its potential aversive consequences, which only in a minority of cases was dominated by fear of pain or injury. Conclusion: Assumptions of fear as the basis of activity avoidance should not be used uncritically in clinical settings. Decisions about activity should explore beyond pain expectancy, incorporating goals, values, and decision processes. Summary points The model of fear of pain or re/injury and associated avoidance, an important insight that has generated effective therapeutic interventions, risks being over-applied and assumed rather than demonstrated. Patients’ own accounts, using qualitative analysis of interview in 11 women with long term chronic pain associated with joint hypermobility, give a more nuanced description of complex decision-making around activity. While a few activities were unquestionably avoided because of such fears, others were undertaken when benefits

  8. Active graph matching for automatic joint segmentation and annotation of C. elegans.

    PubMed

    Kainmueller, Dagmar; Jug, Florian; Rother, Carsten; Myers, Gene

    2014-01-01

    In this work we present a novel technique we term active graph matching, which integrates the popular active shape model into a sparse graph matching problem. This way we are able to combine the benefits of a global, statistical deformation model with the benefits of a local deformation model in form of a second-order random field. We present a new iterative energy minimization technique which achieves empirically good results. This enables us to exceed state-of-the art results for the task of annotating nuclei in 3D microscopic images of C. elegans. Furthermore with the help of the generalized Hough transform we are able to jointly segment and annotate a large set of nuclei in a fully automatic fashion for the first time. PMID:25333104

  9. Monitoring of bolted joints using piezoelectric active-sensing for aerospace applications

    SciTech Connect

    Park, Gyuhae; Farrar, Charles R; Park, Chan - Yik; Jun, Seung - Moon

    2010-01-01

    This paper is a report of an initial investigation into tracking and monitoring the integrity of bolted joints using piezoelectric active-sensors. The target application of this study is a fitting lug assembly of unmanned aerial vehicles (UAVs), where a composite wing is mounted to a UAV fuselage. The SHM methods deployed in this study are impedance-based SHM techniques, time-series analysis, and high-frequency response functions measured by piezoelectric active-sensors. Different types of simulated damage are introduced into the structure, and the capability of each technique is examined and compared. Additional considerations encountered in this initial investigation are made to guide further thorough research required for the successful field deployment of this technology.

  10. Atypical brain activation patterns during a face-to-face joint attention game in adults with autism spectrum disorder.

    PubMed

    Redcay, Elizabeth; Dodell-Feder, David; Mavros, Penelope L; Kleiner, Mario; Pearrow, Mark J; Triantafyllou, Christina; Gabrieli, John D; Saxe, Rebecca

    2013-10-01

    Joint attention behaviors include initiating one's own and responding to another's bid for joint attention to an object, person, or topic. Joint attention abilities in autism are pervasively atypical, correlate with development of language and social abilities, and discriminate children with autism from other developmental disorders. Despite the importance of these behaviors, the neural correlates of joint attention in individuals with autism remain unclear. This paucity of data is likely due to the inherent challenge of acquiring data during a real-time social interaction. We used a novel experimental set-up in which participants engaged with an experimenter in an interactive face-to-face joint attention game during fMRI data acquisition. Both initiating and responding to joint attention behaviors were examined as well as a solo attention (SA) control condition. Participants included adults with autism spectrum disorder (ASD) (n = 13), a mean age- and sex-matched neurotypical group (n = 14), and a separate group of neurotypical adults (n = 22). Significant differences were found between groups within social-cognitive brain regions, including dorsal medial prefrontal cortex (dMPFC) and right posterior superior temporal sulcus (pSTS), during the RJA as compared to SA conditions. Region-of-interest analyses revealed a lack of signal differentiation between joint attention and control conditions within left pSTS and dMPFC in individuals with ASD. Within the pSTS, this lack of differentiation was characterized by reduced activation during joint attention and relative hyper-activation during SA. These findings suggest a possible failure of developmental neural specialization within the STS and dMPFC to joint attention in ASD. PMID:22505330

  11. Effect of lower-limb joint models on subject-specific musculoskeletal models and simulations of daily motor activities.

    PubMed

    Valente, Giordano; Pitto, Lorenzo; Stagni, Rita; Taddei, Fulvia

    2015-12-16

    Understanding the validity of using musculoskeletal models is critical, making important to assess how model parameters affect predictions. In particular, assumptions on joint models can affect predictions from simulations of movement, and the identification of image-based joints is unavoidably affected by uncertainty that can decrease the benefits of increasing model complexity. We evaluated the effect of different lower-limb joint models on muscle and joint contact forces during four motor tasks, and assessed the sensitivity to the uncertainties in the identification of anatomical four-bar-linkage joints. Three MRI-based musculoskeletal models having different knee and ankle joint models were created and used for the purpose. Model predictions were compared against a baseline model including simpler and widely-adopted joints. In addition, a probabilistic analysis was performed by perturbing four-bar-linkage joint parameters according to their uncertainty. The differences between models depended on the motor task analyzed, and there could be marked differences at peak loading (up to 2.40 BW at the knee and 1.54 BW at the ankle), although they were rather small over the motor task cycles (up to 0.59 BW at the knee and 0.31 BW at the ankle). The model including more degrees of freedom showed more discrepancies in predicted muscle activations compared to measured muscle activity. Further, including image-based four-bar-linkages was robust to simulate walking, chair rise and stair ascent, but not stair descent (peak standard deviation of 2.66 BW), suggesting that joint model complexity should be set according to the imaging dataset available and the intended application, performing sensitivity analyses. PMID:26506255

  12. Strength and isometric torque control in individuals with Parkinson's disease.

    PubMed

    Oliveira, Marcio Alves; de Oliveira, Marcio Alves; Rodrigues, Ana Melissa; Caballero, Raphael Maciel Silva; da Silva Caballero, Raphael Maciel; Petersen, Ricardo Demetrio; de Souza Petersen, Ricardo Demetrio; Shim, Jae Kun

    2008-01-01

    It has been previously reported that patients with Parkinson's disease (PD) struggle with fine adjustments of finger forces while manipulating an object. However, impairments in everyday activities can not only be attributed to difficulties with the linear forces applied on an object, but also to the application of rotational forces (torque). This study examined finger strength and isometric torque control in elderly persons with PD. Six individuals with PD (66.1 +/- 0.7 years), six elderly healthy controls (65.3 +/- 0.2 years) matched by age, gender and handedness, and six young adults (22.3 +/- 0.2 years) participated in this study. The subjects were asked to perform two tasks: maximum voluntary thumb-index pinching torque production (MVT) and constant isometric thumb-index torque control at 40% of their MVT for 20 s. The results showed decreased strength and increased difficulty in isometric torque control in individuals with PD as compared to their healthy peers. This study demonstrates that PD affects isometric finger torque production and control. PMID:18030452

  13. Differentiation between non-neural and neural contributors to ankle joint stiffness in cerebral palsy

    PubMed Central

    2013-01-01

    Background Spastic paresis in cerebral palsy (CP) is characterized by increased joint stiffness that may be of neural origin, i.e. improper muscle activation caused by e.g. hyperreflexia or non-neural origin, i.e. altered tissue viscoelastic properties (clinically: “spasticity” vs. “contracture”). Differentiation between these components is hard to achieve by common manual tests. We applied an assessment instrument to obtain quantitative measures of neural and non-neural contributions to ankle joint stiffness in CP. Methods Twenty-three adolescents with CP and eleven healthy subjects were seated with their foot fixated to an electrically powered single axis footplate. Passive ramp-and-hold rotations were applied over full ankle range of motion (RoM) at low and high velocities. Subject specific tissue stiffness, viscosity and reflexive torque were estimated from ankle angle, torque and triceps surae EMG activity using a neuromuscular model. Results In CP, triceps surae reflexive torque was on average 5.7 times larger (p = .002) and tissue stiffness 2.1 times larger (p = .018) compared to controls. High tissue stiffness was associated with reduced RoM (p < .001). Ratio between neural and non-neural contributors varied substantially within adolescents with CP. Significant associations of SPAT (spasticity test) score with both tissue stiffness and reflexive torque show agreement with clinical phenotype. Conclusions Using an instrumented and model based approach, increased joint stiffness in CP could be mainly attributed to higher reflexive torque compared to control subjects. Ratios between contributors varied substantially within adolescents with CP. Quantitative differentiation of neural and non-neural stiffness contributors in CP allows for assessment of individual patient characteristics and tailoring of therapy. PMID:23880287

  14. Effects of balance training by knee joint motions on muscle activity in adult men with functional ankle instability

    PubMed Central

    Nam, Seung-min; Kim, Won-bok; Yun, Chang-kyo

    2016-01-01

    [Purpose] This study examined the effects of balance training by applying knee joint movements on muscle activity in male adults with functional ankle instability. [Subjects and Methods] 28 adults with functional ankle instability, divided randomly into an experimental group, which performed balance training by applying knee joint movements for 20 minutes and ankle joint exercises for 10 minutes, and a control group, which performed ankle joint exercise for 30 minutes. Exercises were completed three times a week for 8 weeks. Electromyographic values of the tibialis anterior, peroneus longus, peroneus brevis, and the lateral gastrocnemius muscles were obtained to compare and analyze muscle activity before and after the experiments in each group. [Results] The experimental group had significant increases in muscle activity in the tibialis anterior, peroneus longus, and lateral gastrocnemius muscles, while muscle activity in the peroneus brevis increased without significance. The control group had significant increases in muscle activity in the tibialis anterior and peroneus longus, while muscle activity in the peroneus brevis and lateral gastrocnemius muscles increased without significance. [Conclusion] In conclusion, balance training by applying knee joint movements can be recommended as a treatment method for patients with functional ankle instability. PMID:27313386

  15. Split torque transmission load sharing

    NASA Technical Reports Server (NTRS)

    Krantz, T. L.; Rashidi, M.; Kish, J. G.

    1992-01-01

    Split torque transmissions are attractive alternatives to conventional planetary designs for helicopter transmissions. The split torque designs can offer lighter weight and fewer parts but have not been used extensively for lack of experience, especially with obtaining proper load sharing. Two split torque designs that use different load sharing methods have been studied. Precise indexing and alignment of the geartrain to produce acceptable load sharing has been demonstrated. An elastomeric torque splitter that has large torsional compliance and damping produces even better load sharing while reducing dynamic transmission error and noise. However, the elastomeric torque splitter as now configured is not capable over the full range of operating conditions of a fielded system. A thrust balancing load sharing device was evaluated. Friction forces that oppose the motion of the balance mechanism are significant. A static analysis suggests increasing the helix angle of the input pinion of the thrust balancing design. Also, dynamic analysis of this design predicts good load sharing and significant torsional response to accumulative pitch errors of the gears.

  16. Peripheral and spinal activation of cannabinoid receptors by joint mobilization alleviates postoperative pain in mice.

    PubMed

    Martins, D F; Mazzardo-Martins, L; Cidral-Filho, F J; Gadotti, V M; Santos, A R S

    2013-01-01

    The present study was undertaken to investigate the relative contribution of cannabinoid receptors (CBRs) subtypes and to analyze cannabimimetic mechanisms involved in the inhibition of anandamide (AEA) and 2-arachidonoyl glycerol degradation on the antihyperalgesic effect of ankle joint mobilization (AJM). Mice (25-35g) were subjected to plantar incision (PI) and 24h after surgery animals received the following treatments, AJM for 9min, AEA (10mg/kg, intraperitoneal [i.p.]), WIN 55,212-2 (1.5mg/kg, i.p.), URB937 (0.01-1mg/kg, i.p.; a fatty acid amide hydrolase [FAAH] inhibitor) or JZL184 (0.016-16mg/kg, i.p.; a monoacylglycerol lipase [MAGL] inhibitor). Withdrawal frequency to mechanical stimuli was assessed 24h after PI and at different time intervals after treatments. Receptor specificity was investigated using selective CB1R (AM281) and CB2R (AM630) antagonists. In addition, the effect of the FAAH and MAGL inhibitors on the antihyperalgesic action of AJM was investigated. AJM, AEA, WIN 55,212-2, URB937 and JZL184 decreased mechanical hyperalgesia induced by PI. The antihyperalgesic effect of AJM was reversed by pretreatment with AM281 given by intraperitoneal and intrathecal routes, but not intraplantarly. Additionally, intraperitoneal and intraplantar, but not intrathecal administration of AM630 blocked AJM-induced antihyperalgesia. Interestingly, in mice pretreated with FAAH or the MAGL inhibitor the antihyperalgesic effect of AJM was significantly longer. This article presents data addressing the CBR mechanisms underlying the antihyperalgesic activity of joint mobilization as well as of the endocannabinoid catabolic enzyme inhibitors in the mouse postoperative pain model. Joint mobilization and these enzymes offer potential targets to treat postoperative pain. PMID:24120553

  17. Role of Synchronous Activation of Cerebellar Purkinje Cell Ensembles in Multi-joint Movement Control

    PubMed Central

    Hoogland, Tycho M.; De Gruijl, Jornt R.; Witter, Laurens; Canto, Cathrin B.; De Zeeuw, Chris I.

    2015-01-01

    Summary It is a longstanding question in neuroscience how elaborate multi-joint movements are coordinated coherently. Microzones of cerebellar Purkinje cells (PCs) are thought to mediate this coordination by controlling the timing of particular motor domains. However, it remains to be elucidated to what extent motor coordination deficits can be correlated with abnormalities in coherent activity within these microzones and to what extent artificially evoked synchronous activity within PC ensembles can elicit multi-joint motor behavior. To study PC ensemble correlates of limb, trunk, and tail movements, we developed a transparent disk treadmill that allows quantitative readout of locomotion and posture parameters in head-fixed mice and simultaneous cellular-resolution imaging and/or optogenetic manipulation. We show that PC ensembles in the ataxic and dystonic mouse mutant tottering have a reduced level of complex spike co-activation, which is delayed relative to movement onset and co-occurs with prolonged swing duration and reduced phase coupling of limb movements as well as with enlarged deflections of body-axis and tail movements. Using optogenetics to increase simple spike rate in PC ensembles, we find that preferred locomotion and posture patterns can be elicited or perturbed depending on the behavioral state. At rest, preferred sequences of limb movements can be elicited, whereas during locomotion, preferred gait-inhibition patterns are evoked. Our findings indicate that synchronous activation of PC ensembles can facilitate initiation and coordination of limb and trunk movements, presumably by tuning downstream systems involved in the execution of behavioral patterns. PMID:25843032

  18. The mechanical and tribological properties of UHMWPE loaded ALN after mechanical activation for joint replacements.

    PubMed

    Gong, Kemeng; Qu, Shuxin; Liu, Yumei; Wang, Jing; Zhang, Yongchao; Jiang, Chongxi; Shen, Ru

    2016-08-01

    Ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN) has tremendous potential as an orthopeadic biomaterial for joint replacements. However, poor mechanical and tribological properties of UHMWPE-ALN are still obstacle for further application. The purpose of this study was to investigate the effect and mechanism of mechanical activation on mechanical and tribological properties of 1wt% ALN-loaded UHMWPE (UHMWPE-ALN-ma). In this study, tensile test, small punch test and reciprocating sliding wear test were applied to characterize the mechanical and tribological properties of UHMWPE-ALN-ma. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize UHMWPE-ALN-ma. Tensile test and small punch test showed that Young׳s modulus, tensile strength and work-to-failure (WTF) of UHMWPE-ALN-ma increased significantly compared to those of UHMWPE-ALN. The friction coefficients and wear factors of UHMWPE-ALN-ma both decreased significantly compared to those of UHMWPE-ALN. Mechanical activation obviously reduced type 1 (void) and type 2 (the disconnected and dislocated machining marks) fusion defects of UHMWPE-ALN-ma, which were revealed by SEM images of freeze fracture surfaces after etching and lateral surfaces of specimens after extension to fracture, respectively. It was attributed to peeled-off layers and chain scission of molecular chains of UHMWPE particles after mechanical activation, which were revealed by SEM images and FTIR spectra of UHMWPE-ALN-ma and UHMWPE-ALN, respectively. Moreover, EDS spectra revealed the more homogeneous distribution of ALN in UHMWPE-ALN-ma compared to that of UHMWPE-ALN. The present results showed that mechanical activation was a potential strategy to improve mechanical and tribological properties of UHMWPE-ALN-ma as an orthopeadic biomaterial for joint replacements. PMID:27104932

  19. Self-adjusting, isostatic exoskeleton for the human knee joint.

    PubMed

    Cai, Viet Anh Dung; Bidaud, Philippe; Hayward, Vincent; Gosselin, Florian; Desailly, Eric

    2011-01-01

    A knee-joint exoskeleton design that can apply programmable torques to the articulation and that self-adjusts to its physiological movements is described. Self-adjustment means that the articular torque is automatically produced around the rotational axis of the joint. The requirements are first discussed and the conditions under which the system tracks the spatial relative movements of the limbs are given. If these conditions are met, the torque applied to the joint takes into account the possible relative movements of the limbs without introducing constraints. A prototype was built to demonstrate the applicability of these principles and preliminary tests were carried out to validate the design. PMID:22254384

  20. Rolling-Convolute Joint For Pressurized Glove

    NASA Technical Reports Server (NTRS)

    Kosmo, Joseph J.; Bassick, John W.

    1994-01-01

    Rolling-convolute metacarpal/finger joint enhances mobility and flexibility of pressurized glove. Intended for use in space suit to increase dexterity and decrease wearer's fatigue. Also useful in diving suits and other pressurized protective garments. Two ring elements plus bladder constitute rolling-convolute joint balancing torques caused by internal pressurization of glove. Provides comfortable grasp of various pieces of equipment.

  1. Fine-tuning motor torque

    SciTech Connect

    O`Connor, L.

    1996-01-01

    Direct-torque control, a new method of regulating the output of ac induction motors, provides a swift response to input commands. A new variable-speed ac motor drive system that responds to torque input commands 10 times faster than current state-of-the-art drives has been developed by ABB Industrial Systems Inc. in New Berlin, Wis. The new control system, called the ACS 600, provides an alternative to drive systems that use sophisticated flux vector control or more routine pulse width modulation--the primary methods of regulating the output of ac induction motors. The ACS 600 is suitable for use in single motor applications that require a standard level of performance, such as conveyors, fans, and pumps. But it will likely be more valuable in applications that require the linking of multiple motors, such as textile production, and in applications that require tight control over torque, such as cranes, elevators, and centrifuges.

  2. Temporal Expectation and Attention Jointly Modulate Auditory Oscillatory Activity in the Beta Band

    PubMed Central

    Todorovic, Ana; Schoffelen, Jan-Mathijs; van Ede, Freek; Maris, Eric; de Lange, Floris P.

    2015-01-01

    The neural response to a stimulus is influenced by endogenous factors such as expectation and attention. Current research suggests that expectation and attention exert their effects in opposite directions, where expectation decreases neural activity in sensory areas, while attention increases it. However, expectation and attention are usually studied either in isolation or confounded with each other. A recent study suggests that expectation and attention may act jointly on sensory processing, by increasing the neural response to expected events when they are attended, but decreasing it when they are unattended. Here we test this hypothesis in an auditory temporal cueing paradigm using magnetoencephalography in humans. In our study participants attended to, or away from, tones that could arrive at expected or unexpected moments. We found a decrease in auditory beta band synchrony to expected (versus unexpected) tones if they were unattended, but no difference if they were attended. Modulations in beta power were already evident prior to the expected onset times of the tones. These findings suggest that expectation and attention jointly modulate sensory processing. PMID:25799572

  3. Joint Spacelab-J (SL-J) Activities at the Huntsville Operations Support Center (HOSC) Spacelab

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The science laboratory, Spacelab-J (SL-J), flown aboard the STS-47 flight was a joint venture between NASA and the National Space Development Agency of Japan (NASDA) utilizing a manned Spacelab module. The mission conducted 24 materials science and 20 life science experiments, of which 35 were sponsored by NASDA, 7 by NASA, and two collaborative efforts. Materials science investigations covered such fields as biotechnology, electronic materials, fluid dynamics and transport phenomena, glasses and ceramics, metals and alloys, and acceleration measurements. Life sciences included experiments on human health, cell separation and biology, developmental biology, animal and human physiology and behavior, space radiation, and biological rhythms. Test subjects included the crew, Japanese koi fish (carp), cultured animal and plant cells, chicken embryos, fruit flies, fungi and plant seeds, and frogs and frog eggs. Featured together in joint ground activities during the SL-J mission are NASA/NASDA personnel at the Huntsville Operations Support Center (HOSC) Spacelab Payload Operations Control Center (SL POCC) at Marshall Space Flight Center (MSFC).

  4. Hedgehog inhibits β-catenin activity in synovial joint development and osteoarthritis

    PubMed Central

    Rockel, Jason S.; Yu, Chunying; Whetstone, Heather; Craft, April M.; Reilly, Katherine; Ma, Henry; Tsushima, Hidetoshi; Puviindran, Vijitha; Al-Jazrawe, Mushriq; Keller, Gordon M.; Alman, Benjamin A.

    2016-01-01

    Both the WNT/β-catenin and hedgehog signaling pathways are important in the regulation of limb development, chondrocyte differentiation, and degeneration of articular cartilage in osteoarthritis (OA). It is not clear how these signaling pathways interact in interzone cell differentiation and synovial joint morphogenesis. Here, we determined that constitutive activation of hedgehog signaling specifically within interzone cells induces joint morphological changes by selectively inhibiting β-catenin–induced Fgf18 expression. Stabilization of β-catenin or treatment with FGF18 rescued hedgehog-induced phenotypes. Hedgehog signaling induced expression of a dominant negative isoform of TCF7L2 (dnTCF7L2) in interzone progeny, which may account for the selective regulation of β-catenin target genes observed. Knockdown of TCF7L2 isoforms in mouse chondrocytes rescued hedgehog signaling–induced Fgf18 downregulation, while overexpression of the human dnTCF7L2 orthologue (dnTCF4) in human chondrocytes promoted the expression of catabolic enzymes associated with OA. Similarly, expression of dnTCF4 in human chondrocytes positively correlated with the aggrecanase ADAMTS4. Consistent with our developmental findings, activation of β-catenin also attenuated hedgehog-induced or surgically induced articular cartilage degeneration in mouse models of OA. Thus, our results demonstrate that hedgehog inhibits selective β-catenin target gene expression to direct interzone progeny fates and articular cartilage development and disease. Moreover, agents that increase β-catenin activity have the potential to therapeutically attenuate articular cartilage degeneration as part of OA. PMID:27018594

  5. Joint maximum likelihood estimation of activation and Hemodynamic Response Function for fMRI.

    PubMed

    Bazargani, Negar; Nosratinia, Aria

    2014-07-01

    Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) maps the brain activity by measuring blood oxygenation level, which is related to brain activity via a temporal impulse response function known as the Hemodynamic Response Function (HRF). The HRF varies from subject to subject and within areas of the brain, therefore a knowledge of HRF is necessary for accurately computing voxel activations. Conversely a knowledge of active voxels is highly beneficial for estimating the HRF. This work presents a joint maximum likelihood estimation of HRF and activation based on low-rank matrix approximations operating on regions of interest (ROI). Since each ROI has limited data, a smoothing constraint on the HRF is employed via Tikhonov regularization. The method is analyzed under both white noise and colored noise. Experiments with synthetic data show that accurate estimation of the HRF is possible with this method without prior assumptions on the exact shape of the HRF. Further experiments involving real fMRI experiments with auditory stimuli are used to validate the proposed method. PMID:24835179

  6. A cable-driven wrist robotic rehabilitator using a novel torque-field controller for human motion training

    NASA Astrophysics Data System (ADS)

    Chen, Weihai; Cui, Xiang; Zhang, Jianbin; Wang, Jianhua

    2015-06-01

    Rehabilitation technologies have great potentials in assisted motion training for stroke patients. Considering that wrist motion plays an important role in arm dexterous manipulation of activities of daily living, this paper focuses on developing a cable-driven wrist robotic rehabilitator (CDWRR) for motion training or assistance to subjects with motor disabilities. The CDWRR utilizes the wrist skeletal joints and arm segments as the supporting structure and takes advantage of cable-driven parallel design to build the system, which brings the properties of flexibility, low-cost, and low-weight. The controller of the CDWRR is designed typically based on a virtual torque-field, which is to plan "assist-as-needed" torques for the spherical motion of wrist responding to the orientation deviation in wrist motion training. The torque-field controller can be customized to different levels of rehabilitation training requirements by tuning the field parameters. Additionally, a rapidly convergent parameter self-identification algorithm is developed to obtain the uncertain parameters automatically for the floating wearable structure of the CDWRR. Finally, experiments on a healthy subject are carried out to demonstrate the performance of the controller and the feasibility of the CDWRR on wrist motion training or assistance.

  7. A cable-driven wrist robotic rehabilitator using a novel torque-field controller for human motion training.

    PubMed

    Chen, Weihai; Cui, Xiang; Zhang, Jianbin; Wang, Jianhua

    2015-06-01

    Rehabilitation technologies have great potentials in assisted motion training for stroke patients. Considering that wrist motion plays an important role in arm dexterous manipulation of activities of daily living, this paper focuses on developing a cable-driven wrist robotic rehabilitator (CDWRR) for motion training or assistance to subjects with motor disabilities. The CDWRR utilizes the wrist skeletal joints and arm segments as the supporting structure and takes advantage of cable-driven parallel design to build the system, which brings the properties of flexibility, low-cost, and low-weight. The controller of the CDWRR is designed typically based on a virtual torque-field, which is to plan "assist-as-needed" torques for the spherical motion of wrist responding to the orientation deviation in wrist motion training. The torque-field controller can be customized to different levels of rehabilitation training requirements by tuning the field parameters. Additionally, a rapidly convergent parameter self-identification algorithm is developed to obtain the uncertain parameters automatically for the floating wearable structure of the CDWRR. Finally, experiments on a healthy subject are carried out to demonstrate the performance of the controller and the feasibility of the CDWRR on wrist motion training or assistance. PMID:26133875

  8. Comparison Between a Reference Torque Standard Machine and a Deadweight Torque Standard Machine to BE Used in Torque Calibration

    NASA Astrophysics Data System (ADS)

    Meng, Feng; Zhang, Zhimin; Lin, Jing

    The paper describes the reference torque standard machine with high accuracy and multifunction, developed by our institute, and introduces the structure and working principle of this machine. It has three main functions. The first function is the hydraulic torque wrench calibration function. The second function is torque multiply calibration function. The third function is reference torque standard machine function. We can calibrate the torque multipliers, hydraulic wrenches and transducers by this machine. A comparison experiment has been done between this machine and a deadweight torque standard machine. The consistency between the 30 kNm reference torque machine and the 2000 Nm dead-weight torque standard machine under the claimed uncertainties was verified.

  9. Knee joint laxity and neuromuscular characteristics of male and female soccer and basketball players.

    PubMed

    Rozzi, S L; Lephart, S M; Gear, W S; Fu, F H

    1999-01-01

    Anterior cruciate ligament injuries are occurring at a higher rate in female athletes compared with their male counterparts. Research in the area of anterior cruciate ligament injury has increasingly focused on the role of joint proprioception and muscle activity in promoting knee joint stability. We measured knee joint laxity, joint kinesthesia, lower extremity balance, the amount of time required to generate peak torque of the knee flexor and extensor musculature, and electromyographically assessed muscle activity in 34 healthy, collegiate-level athletes (average age, 19.6 +/- 1.5 years) who played soccer or basketball or both. Independent t-tests were used to determine significant sex differences. Results revealed that women inherently possess significantly greater knee joint laxity values, demonstrate a significantly longer time to detect the knee joint motion moving into extension, possess significantly superior single-legged balance ability, and produce significantly greater electromyographic peak amplitude and area of the lateral hamstring muscle subsequent to landing a jump. The excessive joint laxity of women appears to contribute to diminished joint proprioception, rendering the knee less sensitive to potentially damaging forces and possibly at risk for injury. Unable to rely on ligamentous structures, healthy female athletes appear to have adopted compensatory mechanisms of increased hamstring activity to achieve functional joint stabilization. PMID:10352766

  10. Large Torque Variations in Two Soft Gamma Repeaters

    NASA Technical Reports Server (NTRS)

    Woods, Peter M.; Kouveliotou, Chryssa; Gogus, Ersin; Finger, Mark H.; Swank, Jean; Markwardt, Craig B.; Hurley, Kevin; vanderKlis, Michiel

    2002-01-01

    We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-Ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor of approximately 4, which persist for several months. Using long-baseline phase-connected timing solutions as well as the overall frequency histories, we construct torque noise power spectra for each SGR (Soft Gamma Repeater). The power spectrum of each source is very red (power-law slope is approximately -3.5). The torque noise power levels are consistent with some accreting systems on timescales of approximately 1 yr, yet the full power spectrum is much steeper in frequency than any known accreting source. To the best of our knowledge, torque noise power spectra with a comparably steep frequency dependence have been seen only in young, glitching radio pulsars (e.g., Vela). The observed changes in spin-down rate do not correlate with burst activity; therefore, the physical mechanisms behind each phenomenon are also likely unrelated. Within the context of the magnetar model, seismic activity can not account for both the bursts and the long-term torque changes unless the seismically active regions are decoupled from one another.

  11. Motion analysis of the glenohumeral joint during activities of daily living.

    PubMed

    Lovern, B; Stroud, L A; Ferran, N A; Evans, S L; Evans, R O; Holt, C A

    2010-12-01

    The shoulder complex has a larger range of motion (ROM) than any other joint complex in the human body, leaving it prone to numerous injuries. Objective kinematic analysis could yield useful functional insights that may assist clinical practice. Non-invasive optoelectronic motion analysis techniques have been used to assess the shoulders of five healthy subjects performing ROM tasks and 10 functional tasks of daily living. The four most demanding tasks - touching the side and back of the head, brushing the opposite side of the head, lifting an object to shoulder height and lifting an object to head height, required 78%, 60%, 61% and 71%, respectively, of the glenohumeral elevation necessary for full abduction in the scapular plane for the 10 shoulders. This has implications for clinical practice where maximum arm elevation is commonly used to determine a patient's ability to return to work and other everyday activities. PMID:21153974

  12. A Method for and Issues Associated with the Determination of Space Suit Joint Requirements

    NASA Technical Reports Server (NTRS)

    Matty, Jennifer E.; Aitchison, Lindsay

    2010-01-01

    This joint mobility KC lecture included information from two papers, "A Method for and Issues Associated with the Determination of Space Suit Joint Requirements" and "Results and Analysis from Space Suit Joint Torque Testing," as presented for the International Conference on Environmental Systems in 2009 and 2010, respectively. The first paper discusses historical joint torque testing methodologies and approaches that were tested in 2008 and 2009. The second paper discusses the testing that was completed in 2009 and 2010.

  13. The influence of target torque and torque build-up time on physical stress in right angle nutrunner operation.

    PubMed

    Oh, S A; Radwin, R G

    1998-02-01

    This study used a computer-controlled electric right angle nutrunner to investigate the relative effects of different power hand tool and process parameters on operator muscular exertions, handle stability and subjective ratings of perceived exertion. Target torque (25, 40 and 55 Nm), torque build-up time (35, 150, 300, 500 and 900 ms), and workstation orientation (horizontal and vertical) were studied. Dependent variables included EMG activity of the finger flexors, biceps, and triceps, handle velocity and displacement, work done on the tool-hand system and power involved in doing work, subjective ratings of perceived exertion, and task acceptance. Six inexperienced subjects (three females and three males) participated. Ten replications were performed for each combination of experimental conditions. The consequences of increasing the torque reaction force were greater handle instability and perceived exertion. The effect of torque build-up time on handle kinematics, muscular activity and perceived exertion was not monotonic. Among five build-up times tested, the hand was most unstable (greater peak handle velocity and power against the operator) for a 150 ms build-up time. Greater peak handle displacement, total work against the operator and average EMG were observed for 150 and 300 ms build-up times than for other build-up time conditions. Integrated EMG and EMG latency significantly increased as build-up time increased. Average EMG latency between the onset of EMG burst and the onset of torque build-up was 40 ms for a 35 ms build-up time and 330 ms for a 900 ms build-up time. Subjective ratings of perceived exertion were the least when torque build-up time was 35 ms, however greater peak torque variance was associated with this condition. PMID:9494431

  14. A structurally decoupled mechanism for measuring wrist torque in three degrees of freedom

    NASA Astrophysics Data System (ADS)

    Pan, Lizhi; Yang, Zhen; Zhang, Dingguo

    2015-10-01

    The wrist joint is a critical part of the human body for movement. Measuring the torque of the wrist with three degrees of freedom (DOFs) is important in some fields, including rehabilitation, biomechanics, ergonomics, and human-machine interfacing. However, the particular structure of the wrist joint makes it difficult to measure the torque in all three directions simultaneously. This work develops a structurally decoupled instrument for measuring and improving the measurement accuracy of 3-DOF wrist torque during isometric contraction. Three single-axis torque sensors were embedded in a customized mechanical structure. The dimensions and components of the instrument were designed based on requirement of manufacturability. A prototype of the instrument was machined, assembled, integrated, and tested. The results show that the structurally decoupled mechanism is feasible for acquiring wrist torque data in three directions either independently or simultaneously. As a case study, we use the device to measure wrist torques concurrently with electromyography signal acquisition in preparation for simultaneous and proportional myoelectric control of prostheses.

  15. A structurally decoupled mechanism for measuring wrist torque in three degrees of freedom.

    PubMed

    Pan, Lizhi; Yang, Zhen; Zhang, Dingguo

    2015-10-01

    The wrist joint is a critical part of the human body for movement. Measuring the torque of the wrist with three degrees of freedom (DOFs) is important in some fields, including rehabilitation, biomechanics, ergonomics, and human-machine interfacing. However, the particular structure of the wrist joint makes it difficult to measure the torque in all three directions simultaneously. This work develops a structurally decoupled instrument for measuring and improving the measurement accuracy of 3-DOF wrist torque during isometric contraction. Three single-axis torque sensors were embedded in a customized mechanical structure. The dimensions and components of the instrument were designed based on requirement of manufacturability. A prototype of the instrument was machined, assembled, integrated, and tested. The results show that the structurally decoupled mechanism is feasible for acquiring wrist torque data in three directions either independently or simultaneously. As a case study, we use the device to measure wrist torques concurrently with electromyography signal acquisition in preparation for simultaneous and proportional myoelectric control of prostheses. PMID:26520970

  16. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine torque. 29.361 Section 29.361... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The limit engine torque may not be less than the following: (a) For turbine engines, the highest of— (1)...

  17. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine torque. 23.361 Section 23.361... Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously...

  18. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine torque. 29.361 Section 29.361... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The limit engine torque may not be less than the following: (a) For turbine engines, the highest of— (1)...

  19. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine torque. 23.361 Section 23.361... Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously...

  20. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Engine torque. 23.361 Section 23.361... Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously...

  1. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine torque. 23.361 Section 23.361... Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously...

  2. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine torque. 29.361 Section 29.361... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The limit engine torque may not be less than the following: (a) For turbine engines, the highest of— (1)...

  3. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Engine torque. 29.361 Section 29.361... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The limit engine torque may not be less than the following: (a) For turbine engines, the highest of— (1)...

  4. Computerized Torque Control for Large dc Motors

    NASA Technical Reports Server (NTRS)

    Willett, Richard M.; Carroll, Michael J.; Geiger, Ronald V.

    1987-01-01

    Speed and torque ranges in generator mode extended. System of shunt resistors, electronic switches, and pulse-width modulation controls torque exerted by large, three-phase, electronically commutated dc motor. Particularly useful for motor operating in generator mode because it extends operating range to low torque and high speed.

  5. 14 CFR 23.361 - Engine torque.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 23.361 Section 23.361... Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously...

  6. 14 CFR 29.361 - Engine torque.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 29.361 Section 29.361... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The limit engine torque may not be less than the following: (a) For turbine engines, the highest of— (1)...

  7. Improved Force-And-Torque Sensor Assembly

    NASA Technical Reports Server (NTRS)

    Bamford, Robert M.

    1991-01-01

    Improved sensor assembly measures forces and torques of interaction between supporting and supported object. Measures all three components of force and all three components of torque. Force measurements uncoupled from torque measurements. Price for improved measurement capability, complexity and flexibility, excessive in some applications.

  8. Comparison of Isokinetic Hip Abduction and Adduction Peak Torques and Ratio Between Sexes

    PubMed Central

    Sugimoto, Dai; Mattacola, Carl G.; Mullineaux, David R.; Palmer, Thomas G.; Hewett, Timothy E.

    2014-01-01

    Objective To evaluate hip abductor and adductor peak torque outputs and compare their ratios between sexes. Design A cross-sectional laboratory-controlled study. Setting Participants visited a laboratory and performed an isokinetic hip abductor and adductor test. All participants performed 2 sets of 5 repetitions of concentric hip abduction and adduction in a standing position at 60 degrees per second. Gravity was determined as a function of joint angle relative to the horizontal plane and was corrected by normalizing the weight of the limb on an individual basis. Participants A total of 36 collegiate athletes. Independent Variable Sex (20 females and 16 males). Main Outcome Measures Bilateral peak hip abductor and adductor torques were measured. The 3 highest peak torque values were averaged for each subject. Results Independent t tests were used to compare sex differences in hip abductor and adductor peak torques and the abductor:adductor peak torque ratios. Males demonstrated significantly greater hip abductor peak torque compared with females (males 1.29 ± 0.24 Nm/kg, females 1.13 ± 0.20 Nm/kg; P = 0.03). Neither hip adductor peak torque nor their ratios differed between sexes. Conclusions Sex differences in hip abductor strength were observed. The role of weaker hip abductors in females deserves further attention and may be a factor for higher risk of knee pathologies. PMID:24905541

  9. The Effects of Vibration Stimuli Applied to the Shoulder Joint on the Activity of the Muscles Around the Shoulder Joint

    PubMed Central

    Lee, Su-kyoung

    2013-01-01

    [Purpose] The present study compared the muscle activity of the upper trapezius with those of the serratus anterior and the lower trapezius when slings, unstable surfaces, were laterally vibrated, to examine the effects of vibration during sling exercises on shoulder stabilization muscles. [Methods] The subjects performed push-up exercises on a sling and maintained isometric contraction in the final stage, while vibration was manually administered to the rope of the sling during the isometric-contraction stage. Vibration within a range of 10 cm was delivered for five seconds at a frequency of 1 Hz in time with a metronome. Vibrations were applied for five seconds at 3 Hz and 3.5 Hz, respectively. [Results] The serratus anterior showed a significant differences between isometric contraction with vibration of 3 Hz and isometric contraction with vibration of 3.5 Hz. [Conclusion] The upper trapezius and the lower trapezius showed prominent changes in muscle activity at 3.5 Hz, and the serratus anterior showed prominent changes in muscle activity at 3 Hz and 3.5 Hz. Therefore, as vibration frequency increased, making the load-bearing surface more unstable, the recruitment of the upper trapezius, the lower trapezius, and the serratus anterior increased. To perform exercises that selectively strengthen the serratus anterior, the exercises should be performed at a vibration frequency of 3 Hz. PMID:24396199

  10. Joint swelling

    MedlinePlus

    Swelling of a joint ... Joint swelling may occur along with joint pain . The swelling may cause the joint to appear larger or abnormally shaped. Joint swelling can cause pain or stiffness. After an ...

  11. Joint Spatial-Spectral Feature Space Clustering for Speech Activity Detection from ECoG Signals

    PubMed Central

    Kanas, Vasileios G.; Mporas, Iosif; Benz, Heather L.; Sgarbas, Kyriakos N.; Bezerianos, Anastasios; Crone, Nathan E.

    2014-01-01

    Brain machine interfaces for speech restoration have been extensively studied for more than two decades. The success of such a system will depend in part on selecting the best brain recording sites and signal features corresponding to speech production. The purpose of this study was to detect speech activity automatically from electrocorticographic signals based on joint spatial-frequency clustering of the ECoG feature space. For this study, the ECoG signals were recorded while a subject performed two different syllable repetition tasks. We found that the optimal frequency resolution to detect speech activity from ECoG signals was 8 Hz, achieving 98.8% accuracy by employing support vector machines (SVM) as a classifier. We also defined the cortical areas that held the most information about the discrimination of speech and non-speech time intervals. Additionally, the results shed light on the distinct cortical areas associated with the two syllable repetition tasks and may contribute to the development of portable ECoG-based communication. PMID:24658248

  12. [Jointed estrogenic activities of bisphenol A and three of its analogs].

    PubMed

    Zhang, Hong-chang; Chen, Liang-yan; Liu, Shu-shen; Yin, Da-qiang

    2009-01-01

    The combined effect of environmental endocrine disruptors (EEDs) is one of the hottest topics. The estrogenic activities of BPA, BPAF, BPAP, BPF were tested based on recombinant gene yeast assay. Six mixtures were designed based on the result of the test,each of which had an equitoxic ratio ray (EC10 or EC50). The EC50 values are 6.81 x 10(-6) mol x L(-1), 7.44 x 10(-7) mol x L(-1), 1.43 x 10(-5) mol x L(-1), 7.52 x 10(-6) mol x L(-1) for BPA, BPAF, BPAP and BPF respectively,which reveals that the estrogenic activities order among the four bisphenols was BPAF> BPA> BPF> BPAP. The experiment shows that when BPA mixes with BPAF, BPAP and BPF in different ratios individually, different combination effects are produced. It reveals that the combined ratios of the components may affect the combined effect. The dose addition model and the independent action model are used to identify the combined effect. They are testified to be more intuitionistic and more comprehensive than other joint effect indices. PMID:19353891

  13. Association of joint occurrence of warm and dry conditions over Greece with anticyclonic activity during summer

    NASA Astrophysics Data System (ADS)

    Hatzaki, Maria; Nastos, Panagiotis; Polychroni, Iliana; Flocas, Helena A.; Kouroutzoglou, John; Dalezios, Nicolas R.

    2016-04-01

    Anticyclones are often associated with extreme phenomena, like prolonged droughts or heatwaves and, thus, they can significantly impact fauna and flora, water resources and public health. In this study, the association of the summer anticyclonic activity with the joint occurrence of extreme warm and dry conditions over Greece is explored. The warm and dry extreme conditions are defined by utilizing the Warm/Dry (WD) index for representative meteorological stations from sub-regions of Greece with different climatic features. The WD index is the number of days over a period (here summer) having at the same time mean air temperature > 75th percentile of daily mean temperature and precipitation < 25th percentile of daily precipitation amounts. The anticyclonic activity is determined by the density of the anticyclonic systems over the greater Mediterranean region, which, during summer, is maximized over the Balkans and the northern African coast. The anticyclonic system density has resulted from the comprehensive climatology of Mediterranean anticyclones that was assembled with the aid of the finding and tracking scheme of the University of Melbourne (MS scheme), using the ERA-Interim mean sea-level pressure fields for 1979-2012. The examination of inter-annual and spatial variations of the WD index in association with shifts of the anticyclonic maxima shows that the different sub-regions of Greece are not affected evenly, stressing the role of the complex topography of the region and the variations in the subtropical jet position.

  14. Joint positioning sense, perceived force level and two-point discrimination tests of young and active elderly adults

    PubMed Central

    Franco, Priscila G.; Santos, Karini B.; Rodacki, André L. F.

    2015-01-01

    Background: Changes in the proprioceptive system are associated with aging. Proprioception is important to maintaining and/or recovering balance and to reducing the risk of falls. Objective: To compare the performance of young and active elderly adults in three proprioceptive tests. Method: Twenty-one active elderly participants (66.9±5.5 years) and 21 healthy young participants (24.6±3.9 years) were evaluated in the following tests: perception of position of the ankle and hip joints, perceived force level of the ankle joint, and two-point discrimination of the sole of the foot. Results: No differences (p>0.05) were found between groups for the joint position and perceived force level. On the other hand, the elderly participants showed lower sensitivity in the two-point discrimination (higher threshold) when compared to the young participants (p < 0.01). Conclusion: Except for the cutaneous plantar sensitivity, the active elderly participants had maintained proprioception. Their physical activity status may explain similarities between groups for the joint position sense and perceived force level, however it may not be sufficient to prevent sensory degeneration with aging. PMID:26443978

  15. Estimation of Electrically-Evoked Knee Torque from Mechanomyography Using Support Vector Regression

    PubMed Central

    Ibitoye, Morufu Olusola; Hamzaid, Nur Azah; Abdul Wahab, Ahmad Khairi; Hasnan, Nazirah; Olatunji, Sunday Olusanya; Davis, Glen M.

    2016-01-01

    The difficulty of real-time muscle force or joint torque estimation during neuromuscular electrical stimulation (NMES) in physical therapy and exercise science has motivated recent research interest in torque estimation from other muscle characteristics. This study investigated the accuracy of a computational intelligence technique for estimating NMES-evoked knee extension torque based on the Mechanomyographic signals (MMG) of contracting muscles that were recorded from eight healthy males. Simulation of the knee torque was modelled via Support Vector Regression (SVR) due to its good generalization ability in related fields. Inputs to the proposed model were MMG amplitude characteristics, the level of electrical stimulation or contraction intensity, and knee angle. Gaussian kernel function, as well as its optimal parameters were identified with the best performance measure and were applied as the SVR kernel function to build an effective knee torque estimation model. To train and test the model, the data were partitioned into training (70%) and testing (30%) subsets, respectively. The SVR estimation accuracy, based on the coefficient of determination (R2) between the actual and the estimated torque values was up to 94% and 89% during the training and testing cases, with root mean square errors (RMSE) of 9.48 and 12.95, respectively. The knee torque estimations obtained using SVR modelling agreed well with the experimental data from an isokinetic dynamometer. These findings support the realization of a closed-loop NMES system for functional tasks using MMG as the feedback signal source and an SVR algorithm for joint torque estimation. PMID:27447638

  16. Direct torque control of permanent magnet drives

    SciTech Connect

    French, C.; Acarnley, P.

    1995-12-31

    Many permanent magnet motor drives use an open loop form of torque control, based on the assumption that output torque is proportional to applied current. In a practical motor this assumption may not always be correct, due to sub-optimal alignment of magnets, non-uniformity of magnetic material, current sensor non-linearities and current controller limitations. These factors, together with non-optimized current references, can lead to high values of torque ripple and copper loss. This paper describes a method of estimating the electro-magnetic torque from the rate of change of co-energy with respect to position, thus taking account of mutual torque, reluctance torque and saturation effects. The paper shows how the estimator can be used in a direct torque control scheme. The direct torque controller maximizes the torque:copper loss ratio. Implementation of the direct torque controller in a DSP based drive system is described, with steady-state and transient experimental results illustrating the effectiveness of the direct torque control scheme.

  17. Active Metal Brazing and Characterization of Brazed Joints in Titanium to Carbon-Carbon Composites

    NASA Technical Reports Server (NTRS)

    Singh, M.; Shpargel, T. P.; Morscher, G. N.; Asthana, R.

    2006-01-01

    The Ti-metal/C-C composite joints were formed by reactive brazing with three commercial brazes, namely, Cu-ABA, TiCuNi, and TiCuSiI. The joint microstructures were examined using optical microscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). The results of the microstructure analysis indicate solute redistribution across the joint and possible metallurgical bond formation via interdiffusion, which led to good wetting and spreading. A tube-on-plate tensile test was used to evaluate joint strength of Ti-tube/ C-C composite joints. The load-carrying ability was greatest for the Cu-ABA braze joint structures. This system appeared to have the best braze spreading which resulted in a larger braze/C-C composite bonded area compared to the other two braze materials. Also, joint loadcarrying ability was found to be higher for joint structures where the fiber tows in the outer ply of the C-C composite were aligned perpendicular to the tube axis when compared to the case where fiber tows were aligned parallel to the tube axis.

  18. Forelimb muscle activity during equine locomotion.

    PubMed

    Harrison, Simon M; Whitton, R Chris; King, Melissa; Haussler, Kevin K; Kawcak, Chris E; Stover, Susan M; Pandy, Marcus G

    2012-09-01

    Few quantitative data exist to describe the activity of the distal muscles of the equine forelimb during locomotion, and there is an incomplete understanding of the functional roles of the majority of the forelimb muscles. Based on morphology alone it would appear that the larger proximal muscles perform the majority of work in the forelimb, whereas the smaller distal muscles fulfil supplementary roles such as stabilizing the joints and positioning the limb for impact with the ground. We measured the timing and amplitude of the electromyographic activity of the intrinsic muscles of the forelimb in relation to the phase of gait (stance versus swing) and the torque demand placed on each joint during walking, trotting and cantering. We found that all forelimb muscles, except the extensor carpi radialis (ECR), were activated just prior to hoof-strike and deactivated during stance. Only the ECR was activated during swing. The amplitudes of muscle activation typically increased as gait speed increased. However, the amplitudes of muscle activation were not proportional to the net joint torques, indicating that passive structures may also contribute significantly to torque generation. Our results suggest that the smaller distal muscles help to stabilize the forelimb in early stance, in preparation for the passive structures (tendons and ligaments) to be stretched. The distal forelimb muscles remain active throughout stance only during canter, when the net torques acting about the distal forelimb joints are highest. The larger proximal muscles activate in a complex coordination to position and stabilize the shoulder and elbow joints during ground contact. PMID:22875767

  19. Observational facts regarding the joint activities of the southwest vortex and plateau vortex after its departure from the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yu, Shuhua; Gao, Wenliang; Xiao, Dixiang; Peng, Jun

    2016-01-01

    Using atmospheric observational data from 1998 to 2013, station rainfall data, TRMM (Tropical Rainfall Measuring Mission) data, as well as annual statistics for the plateau vortex and shear line, the joint activity features of sustained departure plateau vortexes (SDPVs) and southwest vortexes (SWVs) are analyzed. Some new and useful observational facts and understanding are obtained about the joint activities of the two types of vortex. The results show that: (1) The joint active period of the two vortexes is from May to August, and mostly in June and July. (2) The SDPVs of the partnership mainly originate near Zaduo, while the SWVs come from Jiulong. (3) Most of the two vortexes move in almost the same direction, moving eastward together with the low trough. The SDPVs mainly act in the area to the north of the Yangtze River, while the SWVs are situated across the Yangtze River valley. (4) The joint activity of the two vortexes often produces sustained regional heavy rainfall to the south of the Yellow River, influencing wide areas of China, and even as far as the Korean Peninsula, Japan and Vietnam. (5) Most of the two vortexes are baroclinic or cold vortexes, and they both become strengthened in terms of their joint activity. (6) When the two vortexes move over the sea, their central pressure descends and their rainfall increases, especially for SWVs. (7) The two vortexes might spin over the same area simultaneously when there are tropical cyclones in the eastern and southern seas of China, or move southward together if a tropical cyclone appears near Hainan Island.

  20. Low-Torque Seal Development

    NASA Technical Reports Server (NTRS)

    Lattime, Scott B.; Borowski, Richard

    2009-01-01

    The EcoTurn Class K production prototypes have passed all AAR qualification tests and received conditional approval. The accelerated life test on the second set of seals is in progress. Due to the performance of the first set, no problems are expected.The seal has demonstrated superior performance over the HDL seal in the test lab with virtually zero torque and excellent contamination exclusion and grease retention.

  1. Common Bolted Joint Analysis Tool

    NASA Technical Reports Server (NTRS)

    Imtiaz, Kauser

    2011-01-01

    Common Bolted Joint Analysis Tool (comBAT) is an Excel/VB-based bolted joint analysis/optimization program that lays out a systematic foundation for an inexperienced or seasoned analyst to determine fastener size, material, and assembly torque for a given design. Analysts are able to perform numerous what-if scenarios within minutes to arrive at an optimal solution. The program evaluates input design parameters, performs joint assembly checks, and steps through numerous calculations to arrive at several key margins of safety for each member in a joint. It also checks for joint gapping, provides fatigue calculations, and generates joint diagrams for a visual reference. Optimum fastener size and material, as well as correct torque, can then be provided. Analysis methodology, equations, and guidelines are provided throughout the solution sequence so that this program does not become a "black box:" for the analyst. There are built-in databases that reduce the legwork required by the analyst. Each step is clearly identified and results are provided in number format, as well as color-coded spelled-out words to draw user attention. The three key features of the software are robust technical content, innovative and user friendly I/O, and a large database. The program addresses every aspect of bolted joint analysis and proves to be an instructional tool at the same time. It saves analysis time, has intelligent messaging features, and catches operator errors in real time.

  2. Spin Transfer Torque in Graphene

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Ching; Chen, Zhihong

    2014-03-01

    Graphene is an idea channel material for spin transport due to its long spin diffusion length. To develop graphene based spin logic, it is important to demonstrate spin transfer torque in graphene. Here, we report the experimental measurement of spin transfer torque in graphene nonlocal spin valve devices. Assisted by a small external in-plane magnetic field, the magnetization reversal of the receiving magnet is induced by pure spin diffusion currents from the injector magnet. The magnetization switching is reversible between parallel and antiparallel configurations by controlling the polarity of the applied charged currents. Current induced heating and Oersted field from the nonlocal charge flow have also been excluded in this study. Next, we further enhance the spin angular momentum absorption at the interface of the receiving magnet and graphene channel by removing the tunneling barrier in the receiving magnet. The device with a tunneling barrier only at the injector magnet shows a comparable nonlocal spin valve signal but lower electrical noise. Moreover, in the same preset condition, the critical charge current density for spin torque in the single tunneling barrier device shows a substantial reduction if compared to the double tunneling barrier device.

  3. The mechanics of activated semitendinosus are not representative of the pathological knee joint condition of children with cerebral palsy.

    PubMed

    Ateş, Filiz; Temelli, Yener; Yucesoy, Can A

    2016-06-01

    Characteristic cerebral palsy effects in the knee include a restricted joint range of motion and forcefully kept joint in a flexed position. To show whether the mechanics of activated spastic semitendinosus muscle are contributing to these effects, we tested the hypothesis that the muscle's joint range of force exertion is narrow and force production capacity in flexed positions is high. The isometric semitendinosus forces of children with cerebral palsy (n=7, mean (SD)=7years (8months), GMFCS levels III-IV, 12 limbs tested) were measured intra-operatively as a function of knee angle, from flexion (120°) to full extension (0°). Peak force measured in the most flexed position was considered as the benchmark. However, peak force (mean (SD)=112.4N (54.3N)) was measured either at intermediate or even full knee extension (three limbs) indicating no narrow joint range of force exertion. Lack of high force production capacity in flexed knee positions (e.g., at 120° negligible or below 22% of the peak force) was shown except for one limb. Therefore, our hypothesis was rejected for a vast majority of the limbs. These findings and those reported for spastic gracilis agree, indicating that the patients' pathological joint condition must rely on a more complex mechanism than the mechanics of individual spastic muscles. PMID:27128957

  4. Design of a knee joint mechanism that adapts to individual physiology.

    PubMed

    Jiun-Yih Kuan; Pasch, Kenneth A; Herr, Hugh M

    2014-01-01

    This paper describes the design of a new knee joint mechanism, called the Adaptive Coupling Joint (ACJ). The new mechanism has an adaptive trajectory of the center of rotations (COR) that automatically matches those of the attached biological joint. The detailed design is presented as well as characterization results of the ACJ. Conventional exoskeleton and assistive devices usually consider limb joints as a one to three degrees of freedom (DOFs) joint synthesized by multiple one-DOF hinge joints in a single plane. However, the biological joints are complex and usually rotate with respect to a changing COR. As a result, the mismatch between limb joint motion and mechanical interface motion can lead to forces that cause undesired ligament and muscle length changes and internal mechanical changes. These undesired changes contribute to discomfort, as well as to the slippage and sluggish interaction between humans and devices. It is shown that the ACJ can transmit planetary torques from either active or passive devices to the limbs without altering the normal biological joint motion. PMID:25570389

  5. Knee and Hip Joint Kinematics Predict Quadriceps and Hamstrings Neuromuscular Activation Patterns in Drop Jump Landings

    PubMed Central

    Malfait, Bart; Dingenen, Bart; Smeets, Annemie; Staes, Filip; Pataky, Todd; Robinson, Mark A.; Vanrenterghem, Jos; Verschueren, Sabine

    2016-01-01

    Purpose The purpose was to assess if variation in sagittal plane landing kinematics is associated with variation in neuromuscular activation patterns of the quadriceps-hamstrings muscle groups during drop vertical jumps (DVJ). Methods Fifty female athletes performed three DVJ. The relationship between peak knee and hip flexion angles and the amplitude of four EMG vectors was investigated with trajectory-level canonical correlation analyses over the entire time period of the landing phase. EMG vectors consisted of the {vastus medialis(VM),vastus lateralis(VL)}, {vastus medialis(VM),hamstring medialis(HM)}, {hamstring medialis(HM),hamstring lateralis(HL)} and the {vastus lateralis(VL),hamstring lateralis(HL)}. To estimate the contribution of each individual muscle, linear regressions were also conducted using one-dimensional statistical parametric mapping. Results The peak knee flexion angle was significantly positively associated with the amplitudes of the {VM,HM} and {HM,HL} during the preparatory and initial contact phase and with the {VL,HL} vector during the peak loading phase (p<0.05). Small peak knee flexion angles were significantly associated with higher HM amplitudes during the preparatory and initial contact phase (p<0.001). The amplitudes of the {VM,VL} and {VL,HL} were significantly positively associated with the peak hip flexion angle during the peak loading phase (p<0.05). Small peak hip flexion angles were significantly associated with higher VL amplitudes during the peak loading phase (p = 0.001). Higher external knee abduction and flexion moments were found in participants landing with less flexed knee and hip joints (p<0.001). Conclusion This study demonstrated clear associations between neuromuscular activation patterns and landing kinematics in the sagittal plane during specific parts of the landing. These findings have indicated that an erect landing pattern, characterized by less hip and knee flexion, was significantly associated with an

  6. Effects of Series Elasticity on the Human Knee Extension Torque-Angle Relationship in Vivo

    ERIC Educational Resources Information Center

    Kubo, Keitaro; Ohgo, Kazuya; Takeishi, Ryuichi; Yoshinaga, Kazunari; Tsunoda, Naoya; Kanehisa, Hiroaki; Fukunaga, Tetsuo

    2006-01-01

    The purpose of this study was to investigate the effects of series elasticity on the torque-angle relationship of the knee extensors in vivo. Forty-two men volunteered to take part in the present study. The participants performed maximal voluntary isometric contractions at eight knee-joint angles (40, 50, 60, 70, 80, 90, 100, 110[degree]). The…

  7. Neural-mechanical feedback control scheme generates physiological ankle torque fluctuation during quiet stance.

    PubMed

    Vette, Albert H; Masani, Kei; Nakazawa, Kimitaka; Popovic, Milos R

    2010-02-01

    We have recently demonstrated in simulations and experiments that a proportional and derivative (PD) feedback controller can regulate the active ankle torque during quiet stance and stabilize the body despite a long sensory-motor time delay. The purpose of the present study was to: 1) model the active and passive ankle torque mechanisms and identify their contributions to the total ankle torque during standing and 2) investigate whether a neural-mechanical control scheme that implements the PD controller as the neural controller can successfully generate the total ankle torque as observed in healthy individuals during quiet stance. Fourteen young subjects were asked to stand still on a force platform to acquire data for model optimization and validation. During two trials of 30 s each, the fluctuation of the body angle, the electromyogram of the right soleus muscle, and the ankle torque were recorded. Using these data, the parameters of: 1) the active and passive torque mechanisms (Model I) and 2) the PD controller within the neural-mechanical control scheme (Model II) were optimized to achieve potential matching between the measured and predicted ankle torque. The performance of the two models was finally validated with a new set of data. Our results indicate that not only the passive, but also the active ankle torque mechanism contributes significantly to the total ankle torque and, hence, to body stabilization during quiet stance. In addition, we conclude that the proposed neural-mechanical control scheme successfully mimics the physiological control strategy during quiet stance and that a PD controller is a legitimate model for the strategy that the central nervous system applies to regulate the active ankle torque in spite of a long sensory-motor time delay. PMID:20071280

  8. Joint Identification of Genetic Variants for Physical Activity in Korean Population

    PubMed Central

    Kim, Jayoun; Kim, Jaehee; Min, Haesook; Oh, Sohee; Kim, Yeonjung; Lee, Andy H.; Park, Taesung

    2014-01-01

    There has been limited research on genome-wide association with physical activity (PA). This study ascertained genetic associations between PA and 344,893 single nucleotide polymorphism (SNP) markers in 8842 Korean samples. PA data were obtained from a validated questionnaire that included information on PA intensity and duration. Metabolic equivalent of tasks were calculated to estimate the total daily PA level for each individual. In addition to single- and multiple-SNP association tests, a pathway enrichment analysis was performed to identify the biological significance of SNP markers. Although no significant SNP was found at genome-wide significance level via single-SNP association tests, 59 genetic variants mapped to 76 genes were identified via a multiple SNP approach using a bootstrap selection stability measure. Pathway analysis for these 59 variants showed that maturity onset diabetes of the young (MODY) was enriched. Joint identification of SNPs could enable the identification of multiple SNPs with good predictive power for PA and a pathway enriched for PA. PMID:25026172

  9. Lipoproteins and their subfractions in psoriatic arthritis: identification of an atherogenic profile with active joint disease

    PubMed Central

    Jones, S; Harris, C; Lloyd, J; Stirling, C; Reckless, J; McHugh, N

    2000-01-01

    OBJECTIVES—(a) To characterise the lipid profile in psoriatic arthritis and investigate whether there are similarities to the dyslipoproteinaemia reported in rheumatoid arthritis and other inflammatory forms of joint disease; (b) to investigate whether there is an atherogenic lipid profile in psoriatic arthritis, which may have a bearing on mortality.
METHODS—Fasting lipids, lipoproteins, and their subfractions were measured in 50 patients with psoriatic arthritis and their age and sex matched controls.
RESULTS—High density lipoprotein cholesterol (HDL cholesterol) and its third subfraction, HDL3 cholesterol, were significantly reduced and the most dense subfraction of low density lipoprotein (LDL), LDL3, was significantly increased in the patients with psoriatic arthritis. Twenty patients with active synovitis had significantly lower total cholesterol, LDL cholesterol, and HDL3 cholesterol than their controls. 25% of the patients with psoriatic arthritis had raised Lp(a) lipoprotein levels (>300 mg/l) compared with 19% of controls, but this was not statistically significant.
CONCLUSION—Raised levels of LDL3 and low levels of HDL cholesterol are associated with coronary artery disease. Such an atherogenic profile in a chronic inflammatory form of arthritis is reported, which may be associated with accelerated mortality.

 PMID:11053070

  10. Partial Antiviral Activities Detection of Chicken Mx Jointing with Neuraminidase Gene (NA) against Newcastle Disease Virus

    PubMed Central

    Zhang, Yani; Fu, Dezhi; Chen, Hao; Zhang, Zhentao; Shi, Qingqing; Elsayed, Ahmed Kamel; Li, Bichun

    2013-01-01

    As an attempt to increase the resistance to Newcastle Disease Virus (NDV) and so further reduction of its risk on the poultry industry. This work aimed to build the eukaryotic gene co-expression plasmid of neuraminidase (NA) gene and myxo-virus resistance (Mx) and detect the gene expression in transfected mouse fibroblasts (NIH-3T3) cells, it is most important to investigate the influence of the recombinant plasmid on the chicken embryonic fibroblasts (CEF) cells. cDNA fragment of NA and mutant Mx gene were derived from pcDNA3.0-NA and pcDNA3.0-Mx plasmid via PCR, respectively, then NA and Mx cDNA fragment were inserted into the multiple cloning sites of pVITRO2 to generate the eukaryotic co-expression plasmid pVITRO2-Mx-NA. The recombinant plasmid was confirmed by restriction endonuclease treatment and sequencing, and it was transfected into the mouse fibroblasts (NIH-3T3) cells. The expression of genes in pVITRO2-Mx-NA were measured by RT-PCR and indirect immunofluorescence assay (IFA). The recombinant plasmid was transfected into CEF cells then RT-PCR and the micro-cell inhibition tests were used to test the antiviral activity for NDV. Our results showed that co-expression vector pVITRO2-Mx-NA was constructed successfully; the expression of Mx and NA could be detected in both NIH-3T3 and CEF cells. The recombinant proteins of Mx and NA protect CEF cells from NDV infection until after 72 h of incubation but the individually mutagenic Mx protein or NA protein protects CEF cells from NDV infection till 48 h post-infection, and co-transfection group decreased significantly NDV infection compared with single-gene transfection group (P<0. 05), indicating that Mx-NA jointing contributed to delaying the infection of NDV in single-cell level and the co-transfection of the jointed genes was more powerful than single one due to their synergistic effects. PMID:23977111

  11. Seasonal Distributions of Mountain Torques during FGGE.

    NASA Astrophysics Data System (ADS)

    Wei, Ming-Ying; Schaack, Todd K.

    1984-10-01

    Based on surface pressure and terrain height analyses from the National Meteorological Center, mountain torques are calculated for January, April, July and October 1979 during the First GARP Global Experiment. The zonally integrated mountain torques are generally in good agreement with previous studies. For all four months, positive torque exists in the tropical latitudes as well as in the polar and subtropical latitudes of the Northern Hemisphere; negative torque exists in northern middle latitudes and most of the Southern Hemisphere. An exception occurs in July when the mountain torque is negative between 5 and 25°N and positive in the Southern Hemisphere subtropics. Over latitudes where large terrain variation exists such as near 20°S due to the Andes, the estimate obtained in this study is larger in magnitude than that from previous work. The difference is due to the differences in both grid resolution and the particular atmospheric data and topography selected.The meridional profiles of individual continental mountain torques are examined to illustrate geographical contributions to the net zonal torque. The positive mountain torque in northern high latitudes is due mainly to North America and Greenland. Both North America and Eurasia contribute to the sink of angular momentum in northern middle latitudes and the source in the subtropical latitudes. The negative torque between 5 and 25°N in July is due to the influence of the Indian monsoon trough on Arabia and Africa. The negative mountain torque over South America dominates the positive torque over Africa and Australia in the Southern Hemisphere in January and October.Although the monthly averaged zonally integrated mountain torque assumes lesser importance when compared to the frictional torque, regional mountain torque at the synoptic time scale is quite large and can have considerable influence on the large scale circulation. Hemispheric torques are in qualitative agreement with previous work. Due to

  12. Activity vs. rest in the treatment of bone, soft tissue and joint injuries.

    PubMed Central

    Buckwalter, J. A.

    1995-01-01

    One of the most important advances in the treatment of musculoskeletal injuries has come from understanding that controlled early resumption of activity can promote restoration of function, and that treatment of injuries with prolonged rest may delay recovery and adversely affect normal tissues. In the last decade of the nineteenth century two widely respected orthopaedists with extensive clinical experience strongly advocated opposing treatments of musculoskeletal injuries. Hugh Owen Thomas in Liverpool believed that enforced, uninterrupted prolonged rest produced the best results. He noted that movement of injured tissues increased inflammation, and that, "It would indeed be as reasonable to attempt to cure a fever patient by kicking him out of bed, as to benefit joint disease by a wriggling at the articulation." Just Lucas-Championnier in Paris took the opposite position. He argued that early controlled active motion accelerated restoration of function, although he noted that mobility had to be given in limited doses. In general, Thomas' views met with greater acceptance in the early part of this century, but experimental studies of the last several decades generally support Lucas-Championneir. They confirm and help explain the deleterious effects of prolonged rest and the beneficial effects of activity on the musculoskeletal tissues. They have shown that maintenance of normal bone, tendon and ligament, articular cartilage and muscle structure and composition require repetitive use, and that changes in the patterns of tissue loading can strengthen or weaken normal tissues. Although all the musculoskeletal tissues can respond to repetitive loading, they vary in the magnitude and type of response to specific patterns of activity. Furthermore, their responsiveness may decline with increasing age. Skeletal muscle and bone demonstrate the most apparent response to changes in activity in individuals of any age. Cartilage and dense fibrous tissues also can respond to

  13. Spin-orbit torque opposing the Oersted torque in ultrathin Co/Pt bilayers

    SciTech Connect

    Skinner, T. D. Irvine, A. C.; Heiss, D.; Kurebayashi, H.; Ferguson, A. J.; Wang, M.; Hindmarch, A. T.; Rushforth, A. W.

    2014-02-10

    Current-induced torques in ultrathin Co/Pt bilayers were investigated using an electrically driven ferromagnetic resonance technique. The angle dependence of the resonances, detected by a rectification effect as a voltage, was analysed to determine the symmetries and relative magnitudes of the spin-orbit torques. Both anti-damping (Slonczewski) and field-like torques were observed. As the ferromagnet thickness was reduced from 3 to 1 nm, the sign of the sum of the field-like torque and Oersted torque reversed. This observation is consistent with the emergence of a Rashba spin orbit torque in ultra-thin bilayers.

  14. Inter-joint coupling strategy during adaptation to novel viscous loads in human arm movement.

    PubMed

    Debicki, D B; Gribble, P L

    2004-08-01

    When arm movements are perturbed by a load, how does the nervous system adjust control signals to reduce error? While it has been shown that the nervous system is capable of compensating for the effects of limb dynamics and external forces, the strategies used to adapt to novel loads are not well understood. We used a robotic exoskeleton [kinesiological instrument for normal and altered reaching movements (KINARM)] to apply novel loads to the arm during single-joint elbow flexions in the horizontal plane (shoulder rotation was allowed). Loads varied in magnitude with the instantaneous velocity of elbow flexion, and were applied to the shoulder in experiment 1 (interaction loads) and the elbow in experiment 2 (direct loads). Initial exposure to both interaction and direct loads resulted in perturbations at both joints, even though the load was applied to only a single joint. Subjects tended to correct for the kinematics of the elbow joint while perturbations at the shoulder persisted. Electromyograms (EMGs) and computed muscle torque showed that subjects modified muscle activity at the elbow to reduce elbow positional deviations. Shoulder muscle activity was also modified; however, these changes were always in the same direction as those at the elbow. Current models of motor control based on inverse-dynamics calculations and force-control, as well as models based on positional control, predict an uncoupling of shoulder and elbow muscle torques for adaptation to these loads. In contrast, subjects in this study adopted a simple strategy of modulating the natural coupling that exists between elbow and shoulder muscle torque during single-joint elbow movements. PMID:15056688

  15. Torque magnetometry in unconventional superconductors

    NASA Astrophysics Data System (ADS)

    Li, Lu

    This thesis describes torque magnetometry studies on unconventional superconductors. Torque magnetometry measures the anisotropic magnetization of samples by recording their torque signals in a tilted magnetic field. Applied to superconductors, this method provides a reliable way to measure the field dependence of magnetization with high resolution under extreme conditions: DC magnetic fields from zero to 45.2 T, and temperature from 300 mK to 300K. The results can be used to determine many important parameters, such as the upper critical field H c2, the superconducting condensation energy, the onset temperature of diamagnetic signals, and so on. We carried out the torque magnetometry measurements on unconventional superconductors---high Tc superconductors and the p-wave superconductor Sr2RuO4---and uncovered new features that do not exist in conventional BCS superconductors. In high Tc superconductors, our torque magnetometry studies focus on the properties of the vortex liquid state. First, by comparing the observed magnetization curves with the Nernst effect results in Bi 2Sr2CaCu2O8+delta, we confirm that the unusually large Nernst effect signals originate from the surviving vortex liquid state above Tc. Second, the M-H curves near the critical temperature Tc suggest that the nature of the transition is the Kosterlitz-Thouless transition. Near Tc, the magnetization response at low field is strongly nonlinear, and the T dependence of the magnetic susceptibility in the low-field limit approaches the predicted curve from the Kosterlitz-Thouless transition. Third, the measurements in intense magnetic field up to 45 T reveal the unusual, weak T-dependence of Hc2. These observations strongly support the existence of the vortex liquid state above Tc. The superconducting state is destroyed by the phase fluctuation of the pair condensate, while the pair condensate keeps its amplitude above T c. Further studies in single-layered high Tc superconductors reveal more

  16. 77 FR 74279 - Agency Information Collection (VA/DOD Joint Disability Evaluation Board Claim): Activity under...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-13

    ... President Bush's Interagency Task Force on Returning Global War on Terror Heroes, VA and the Department of Defense (DOD) have agreed to develop a joint process in which Global War on Terror (GWOT) service...

  17. Large Torque Variations in Two Soft Gamma Repeaters

    NASA Technical Reports Server (NTRS)

    Woods, Peter M.; Kouveliotou, Chryssa; Gogus, Ersin; Finger, Mark H.; Swank, Jean; Markwardt, Craig B.; Hurley, Kevin; vanderKlis, Michiel; Six, N. Frank (Technical Monitor)

    2001-01-01

    We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor of approximately 4, which persist for several months. Using long baseline phase-connected timing solutions as well as the overall frequency histories, we construct torque noise power spectra for each SGR. The power spectrum of each source is very red (power-law slope approximately -3.5). These power spectra are consistent in normalization with some accreting systems, yet much steeper in slope than any known accreting source. To the best of our knowledge, torque noise power spectra with a comparably steep frequency dependence have only been seen in young, glitching radio pulsars (e.g. Vela). The observed changes in spin-down rate do not correlate with burst activity, therefore, the physical mechanisms behind each phenomenon are also likely unrelated. Within the context of the magnetar model, seismic activity cannot account for both the bursts and the long-term torque changes unless the seismically active regions are decoupled from one another.

  18. Torque-consistent 3D force balance and optimization of non-resonant fields in tokamaks

    NASA Astrophysics Data System (ADS)

    Park, Jong-Kyu

    2015-11-01

    A non-axisymmetric magnetic perturbation in tokamaks breaks the toroidal symmetry and produces toroidal torque, which is well known as neoclassical toroidal viscosity (NTV) effects. Although NTV torque is second order, it is the first-order change in the pressure anisotropy that drives currents associated with local torques and thereby modifies the field penetration in force balance. The force operator becomes non-Hermitian, but can be directly solved using parallel, toroidal, and radial force balance, leading to a modified Euler-Lagrange equation. The general perturbed equilibrium code (GPEC), which has been successfully developed to solve the modified Euler-Lagrange equation, gives the torque-consistent 3D force balance as well as self-consistent NTV torque. The self-shielding of the torque becomes apparent in the solutions in high β, which was implied in recent MARS-K applications. Furthermore, the full response matrix including the torque in GPEC provides a new and systematic way of optimizing torque and non-resonant fields. Recently the optimization of 3D fields for torque has been actively studied using the stellarator optimizing tools, but the efficiency and accuracy can be greatly improved by directly incorporating the torque response matrix. There are salient features uncovered by response with the torque, as the response can become invisible in amplitudes but only significant in toroidal phase shift. A perturbation in backward helicity is an example, in which NTV can be induced substantially but quietly without measurable response in amplitudes. A number of other GPEC applications will also be discussed, including the multi-mode responses in high- β tokamak plasmas and the new non-axisymmetric control coil (NCC) design in NSTX-U. This work was supported by DOE Contract DE-AC02-09CH11466.

  19. Landau-Lifshitz theory of thermomagnonic torque

    NASA Astrophysics Data System (ADS)

    Kim, Se Kwon; Tserkovnyak, Yaroslav

    2015-07-01

    We derive the thermomagnonic torque associated with smooth magnetic textures subjected to a temperature gradient in the framework of the stochastic Landau-Lifshitz-Gilbert equation. Our approach captures on equal footing two distinct contributions: (i) a local entropic torque that is caused by a temperature dependence of the effective exchange field, the existence of which had been previously suggested based on numerics, and (ii) the well-known spin-transfer torque induced by thermally induced magnon flow. The dissipative components of two torques have the same structure, following a common phenomenology, but opposite signs, with the twice as large entropic torque leading to a domain-wall motion toward the hotter region. We compare the efficiency of the torque-driven domain-wall motion with the recently proposed Brownian thermophoresis.

  20. Investigation of Motorcycle Steering Torque Components

    NASA Astrophysics Data System (ADS)

    Cossalter, V.; Lot, R.; Massaro, M.; Peretto, M.

    2011-10-01

    When driving along a circular path, the rider controls a motorcycle mainly by the steering torque. This work addresses an in-depth analysis of the steady state cornering and in particular the decomposition of the motorcycle steering torque in its main components, such as road-tyre forces, gyroscopic torques, centrifugal and gravity effects. A detailed and experimentally validated multibody model of the motorcycle is used herein to analyze the steering torque components at different speeds and lateral accelerations. First the road tests are compared with the numerical results for three different vehicles and then a numerical investigation is carried out to decompose the steering torque. Finally, the effect of longitudinal acceleration and deceleration on steering torque components is presented.

  1. Effects of activating fluxes on the weld penetration and corrosion resistant property of laser welded joint of ferritic stainless steel

    NASA Astrophysics Data System (ADS)

    Wang, Yonghui; Hu, Shengsun; Shen, Junqi

    2015-10-01

    This study was based on the ferritic stainless steel SUS430. Under the parallel welding conditions, the critical penetration power values (CPPV) of 3mm steel plates with different surface-coating activating fluxes were tested. Results showed that, after coating with activating fluxes, such as ZrO2, CaCO3, CaF2 and CaO, the CPPV could reduce 100~250 W, which indicating the increases of the weld penetrations (WP). Nevertheless, the variation range of WP with or without activating fluxes was less than 16.7%. Compared with single-component ones, a multi-component activating flux composed of 50% ZrO2, 12.09% CaCO3, 10.43% CaO, and 27.49% MgO was testified to be much more efficient, the WP of which was about 2.3-fold of that without any activating fluxes. Furthermore, a FeCl3 spot corrosion experiment was carried out with samples cut from weld zone to test the effects of different activating fluxes on the corrosion resistant (CR) property of the laser welded joints. It was found that all kinds of activating fluxes could improve the CR of the welded joints. And, it was interesting to find that the effect of the mixed activating fluxes was inferior to those single-component ones. Among all the activating fluxes, the single-component of CaCO3 seemed to be the best in resisting corrosion. By means of Energy Dispersive Spectrometer (EDS) testing, it was found that the use of activating fluxes could effectively restrain the loss of Cr element of weld zone in the process of laser welding, thus greatly improving the CR of welded joints.

  2. Magnetic field control. [electromechanical torquing device

    NASA Technical Reports Server (NTRS)

    Haeussermann, W. (Inventor)

    1982-01-01

    A torque control for an electromechanical torquing device of a type where a variable clearance occurs between a rotor and field is described. A Hall effect device senses the field present, which would vary as a function of spacing between field and rotor. The output of the Hall effect device controls the power applied to the field so as to provide a well defined field and thus a controlled torque to the rotor which is well defined.

  3. Contact pressures in the human hip joint measured in vivo.

    PubMed Central

    Hodge, W A; Fijan, R S; Carlson, K L; Burgess, R G; Harris, W H; Mann, R W

    1986-01-01

    The pressures on human articular cartilage have been measured in vivo. An instrumented femoral head prosthesis that telemeters interarticular pressure at 10 discrete locations 253 times per second was implanted in apposition to natural acetabular cartilage. Data were acquired during surgery, recovery, rehabilitation, and normal activity, for longer than 1 year after surgery. Pressure magnitudes were synchronized with body-segment kinematic data and foot-floor force measurements so as to locate transduced pressure areas on the natural acetabulum and correlate movement kinematics and dynamics with local cartilage pressures. The data reveal very high local (up to 18 MPa) and nonuniform pressures, with abrupt spatial and temporal gradients, that correlate well both in magnitude and distribution with in vitro data and computer simulations of synovial joint mechanics. Peak pressures in vivo are, however, considerably higher than pressures measured in vitro under the putative forces experienced by the joint in life, particularly in normal movements where cocontraction occurs in agonist and antagonist muscles across the hip joint. Thus, extant gait-analysis studies which apply inverse Newtonian calculations to infer joint forces establish the lower limit on such forces, since such analyses include only the net muscular torques about the joint and cannot account for the contribution of the increment in joint force due to muscular cocontraction. Our data also contribute to the understanding of normal synovial joint tribology and the possible role of mechanical factors in the deterioration evident in osteoarthritis. Further, design criteria for both partial and total hip replacement prostheses and specific aspects of rehabilitation protocols following hip surgery (e.g., the extent to which crutches and canes unload the hip joint) warrant reconsideration in light of the extraordinary high pressures measured during the activities of daily living. Images PMID:3458248

  4. Muscle Activation Differs between Three Different Knee Joint-Angle Positions during a Maximal Isometric Back Squat Exercise

    PubMed Central

    Jarbas da Silva, Josinaldo; Jon Schoenfeld, Brad; Nardi, Priscyla Silva Monteiro; Pecoraro, Silvio Luis; D'Andréa Greve, Julia Maria; Hartigan, Erin

    2016-01-01

    The purpose of this study was to compare muscle activation of the lower limb muscles when performing a maximal isometric back squat exercise over three different positions. Fifteen young, healthy, resistance-trained men performed an isometric back squat at three knee joint angles (20°, 90°, and 140°) in a randomized, counterbalanced fashion. Surface electromyography was used to measure muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), semitendinosus (ST), and gluteus maximus (GM). In general, muscle activity was the highest at 90° for the three quadriceps muscles, yet differences in muscle activation between knee angles were muscle specific. Activity of the GM was significantly greater at 20° and 90° compared to 140°. The BF and ST displayed similar activation at all joint angles. In conclusion, knee position alters muscles activation of the quadriceps and gluteus maximus muscles. An isometric back squat at 90° generates the highest overall muscle activation, yet an isometric back squat at 140° generates the lowest overall muscle activation of the VL and GM only. PMID:27504484

  5. Observed frequency-independent torque in flagellar bacterial motors optimizes space exploration.

    PubMed

    Di Salvo, Mario E; Condat, C A

    2012-12-01

    A surprising feature of many bacterial motors is the apparently conserved form of their torque-frequency relation. Experiments indicate that the torque provided by the bacterial rotary motor is approximately constant over a large range of angular speeds. This is observed in both monotrichous and peritrichous bacteria, independently of whether they are propelled by a proton flux or by a Na(+) ion flux. If the relation between angular speed ω and swimming speed is linear, a ω-independent torque implies that the power spent in active motion is proportional to the instantaneous bacterial speed. Using realistic values of the relevant parameters, we show that a constant torque maximizes the volume of the region explored by a bacterium in a resource-depleted medium. Given that nutrients in the ocean are often concentrated in separate, ephemeral patches, we propose that the observed constancy of the torque may be a trait evolved to maximize bacterial survival in the ocean. PMID:23367976

  6. An fMRI study of joint action-varying levels of cooperation correlates with activity in control networks.

    PubMed

    Chaminade, Thierry; Marchant, Jennifer L; Kilner, James; Frith, Christopher D

    2012-01-01

    As social agents, humans continually interact with the people around them. Here, motor cooperation was investigated using a paradigm in which pairs of participants, one being scanned with fMRI, jointly controlled a visually presented object with joystick movements. The object oscillated dynamically along two dimensions, color and width of gratings, corresponding to the two cardinal directions of joystick movements. While the overall control of each participant on the object was kept constant, the amount of cooperation along the two dimensions varied along four levels, from no (each participant controlled one dimension exclusively) to full (each participant controlled half of each dimension) cooperation. Increasing cooperation correlated with BOLD signal in the left parietal operculum and anterior cingulate cortex (ACC), while decreasing cooperation correlated with activity in the right inferior frontal and superior temporal gyri, the intraparietal sulci and inferior temporal gyri bilaterally, and the dorsomedial prefrontal cortex. As joint performance improved with the level of cooperation, we assessed the brain responses correlating with behavior, and found that activity in most of the areas associated with levels of cooperation also correlated with the joint performance. The only brain area found exclusively in the negative correlation with cooperation was in the dorso medial frontal cortex, involved in monitoring action outcome. Given the cluster location and condition-related signal change, we propose that this region monitored actions to extract the level of cooperation in order to optimize the joint response. Our results, therefore, indicate that, in the current experimental paradigm involving joint control of a visually presented object with joystick movements, the level of cooperation affected brain networks involved in action control, but not mentalizing. PMID:22715326

  7. An fMRI study of joint action–varying levels of cooperation correlates with activity in control networks

    PubMed Central

    Chaminade, Thierry; Marchant, Jennifer L.; Kilner, James; Frith, Christopher D.

    2012-01-01

    As social agents, humans continually interact with the people around them. Here, motor cooperation was investigated using a paradigm in which pairs of participants, one being scanned with fMRI, jointly controlled a visually presented object with joystick movements. The object oscillated dynamically along two dimensions, color and width of gratings, corresponding to the two cardinal directions of joystick movements. While the overall control of each participant on the object was kept constant, the amount of cooperation along the two dimensions varied along four levels, from no (each participant controlled one dimension exclusively) to full (each participant controlled half of each dimension) cooperation. Increasing cooperation correlated with BOLD signal in the left parietal operculum and anterior cingulate cortex (ACC), while decreasing cooperation correlated with activity in the right inferior frontal and superior temporal gyri, the intraparietal sulci and inferior temporal gyri bilaterally, and the dorsomedial prefrontal cortex. As joint performance improved with the level of cooperation, we assessed the brain responses correlating with behavior, and found that activity in most of the areas associated with levels of cooperation also correlated with the joint performance. The only brain area found exclusively in the negative correlation with cooperation was in the dorso medial frontal cortex, involved in monitoring action outcome. Given the cluster location and condition-related signal change, we propose that this region monitored actions to extract the level of cooperation in order to optimize the joint response. Our results, therefore, indicate that, in the current experimental paradigm involving joint control of a visually presented object with joystick movements, the level of cooperation affected brain networks involved in action control, but not mentalizing. PMID:22715326

  8. Study on Transmission Torque Characteristics of a Surface-Permanent-Magnet-Type Magnetic Gear

    NASA Astrophysics Data System (ADS)

    Niguchi, Noboru; Hirata, Katsuhiro; Hayakawa, Yuichi

    Magnetic gears have some advantages such as low mechanical loss and maintenance-free operation that are not observed in conventional mechanical gears. In addition, magnetic gears have inherent overload protection. Therefore, magnetic gears are expected to be used in special applications; for example, they can be used in a joint of a humanoid robot. Recently, various types of new magnetic gears have been proposed. Among these new gears, a surface-permanent-magnet-type (SPM-type) magnetic gear employing harmonic magnetic flux has gained attention because of its high transmission torque density, though it has a complex structure with multipole magnets. Some studies on an SPM-type magnetic gear have been carried out, but there are few papers on cogging torque. This paper describes the transmission torque characteristics of an SPM-type magnetic gear. The operating principle and the transmission torque under synchronous operation are formulated in accordance with the gear ratio. High orders of the cogging torque are computed by employing the 3-D finite element method, and the validity of the analysis is verified by carrying out measurements on a prototype. Furthermore, a method for reducing the cogging torque is discussed.

  9. Spin-orbit torques in ferromagnets and antiferromagnets

    NASA Astrophysics Data System (ADS)

    Gao, Huawei

    Spintronics is a sub-field of condensed matter physics which explores the physics of electrons involving both their charge and spin, with an emphasis on the active manipulation of the spin degree of freedom in solid state systems. In spin-based memory and storage devices, information ( 0 or 1) is stored based on the magnetization orientation in ferromagnets or layered magnetic structures. We study the utilization of spin-orbit torques in ferromagnets and antiferromagnets as an effective ways of magnetization switching in these nonvolatile memory devices. The method we use is linear response theory and numerical simulation. Our results show that the spin-orbit torques are effective approaches of manipulating magnetization in both ferromagnets and antiferromagnets, which can be used in the future memory device applications. In ferromagnets, we start from a simple two dimensional electron gas ferromagnetic model with Rashba spin-orbit coupling to study the different components of spin-orbit torques and the parameter dependence. The results show the existence of these torques. Then, we study these torques in a realistic material, GaMnAs, with a complex band structure. We confirm that these torques have the same parameter dependence in GaMnAs and the simple two dimensional model. The complex band structure changes the magnitudes of the effective fields and shows more features in the results which unveils the competition between band structure and spin-orbit coupling. In antiferromagnets, by studying the spin-orbit torques in the two dimensional antiferromagneic model and the realistic material Mn2Au, we predict that a lateral electric current in antiferromagnets can induce non-equilibrium Neel-order fields, i.e., fields whose sign alternates between the spin sub lattices, which can trigger ultrafast spin-axis reorientation. Due to the two dimensional nature, the spin-orbit torques can have large magnitudes if we tune the Fermi energy to a certain level. We then extend

  10. Identification of a Stirling engine's torque characteristics

    SciTech Connect

    Reader, G.T.; Hooper, C.; Taylor, D.R.

    1983-08-01

    The Stirling engine has many advantages claimed for it when compared to other reciprocating heat engines, one of these claimed advantages being the so-called 'smooth torque' characteristic. On further investigation of this virtue it was found that no definitive description of 'smooth torque' existed. With the expansion in recent years of the quantity of Stirling Engine test data it is apparent that some means of obtaining a numerical value for the smoothness of a torque is required. This paper defines a coefficient which enables the smoothness of a torque output to be measured in a definitive way so that comparisons can be made objectively.

  11. Torque limited drive for manual valves

    DOEpatents

    Elliott, Philip G.; Underwood, Daniel E.

    1989-06-06

    The present invention is directed to a torque-limiting handwheel device for preventing manual valves from being damaged due to the application of excessive torque during the opening or closing operation of the valves. Torque can only be applied when ridges in the handwheel assembly engage in channels machined in the face of the baseplate. The amount of torque required for disengagement of the ridges from the channels is determined by the force exerted by various Bellville springs and the inclination of the side faces of the channels.

  12. Torque limited drive for manual valves

    DOEpatents

    Elliott, Philip G.; Underwood, Daniel E.

    1989-01-01

    The present invention is directed to a torque-limiting handwheel device for preventing manual valves from being damaged due to the application of excessive torque during the opening or closing operation of the valves. Torque can only be applied when ridges in the handwheel assembly engage in channels machined in the face of the baseplate. The amount of torque required for disengagement of the ridges from the channels is determined by the force exerted by various Bellville springs and the inclination of the side faces of the channels.

  13. The bHLH-PAS Transcription Factor Dysfusion Regulates Tarsal Joint Formation in Response to Notch Activity during Drosophila Leg Development

    PubMed Central

    Córdoba, Sergio; Estella, Carlos

    2014-01-01

    A characteristic of all arthropods is the presence of flexible structures called joints that connect all leg segments. Drosophila legs include two types of joints: the proximal or “true” joints that are motile due to the presence of muscle attachment and the distal joints that lack musculature. These joints are not only morphologically, functionally and evolutionarily different, but also the morphogenetic program that forms them is distinct. Development of both proximal and distal joints requires Notch activity; however, it is still unknown how this pathway can control the development of such homologous although distinct structures. Here we show that the bHLH-PAS transcription factor encoded by the gene dysfusion (dys), is expressed and absolutely required for tarsal joint development while it is dispensable for proximal joints. In the presumptive tarsal joints, Dys regulates the expression of the pro-apoptotic genes reaper and head involution defective and the expression of the RhoGTPases modulators, RhoGEf2 and RhoGap71E, thus directing key morphogenetic events required for tarsal joint development. When ectopically expressed, dys is able to induce some aspects of the morphogenetic program necessary for distal joint development such as fold formation and programmed cell death. This novel Dys function depends on its obligated partner Tango to activate the transcription of target genes. We also identified a dedicated dys cis-regulatory module that regulates dys expression in the tarsal presumptive leg joints through direct Su(H) binding. All these data place dys as a key player downstream of Notch, directing distal versus proximal joint morphogenesis. PMID:25329825

  14. A hybrid joint based controller for an upper extremity exoskeleton

    NASA Astrophysics Data System (ADS)

    Mohd Khairuddin, Ismail; Taha, Zahari; Majeed, Anwar P. P. Abdul; Hakeem Deboucha, Abdel; Azraai Mohd Razman, Mohd; Aziz Jaafar, Abdul; Mohamed, Zulkifli

    2016-02-01

    This paper presents the modelling and control of a two degree of freedom upper extremity exoskeleton. The Euler-Lagrange formulation was used in deriving the dynamic modelling of both the human upper limb as well as the exoskeleton that consists of the upper arm and the forearm. The human model is based on anthropometrical measurements of the upper limb. The proportional-derivative (PD) computed torque control (CTC) architecture is employed in this study to investigate its efficacy performing joint-space control objectives specifically in rehabilitating the elbow and shoulder joints along the sagittal plane. An active force control (AFC) algorithm is also incorporated into the PD-CTC to investigate the effectiveness of this hybrid system in compensating disturbances. It was found that the AFC- PD-CTC performs well against the disturbances introduced into the system whilst achieving acceptable trajectory tracking as compared to the conventional PD-CTC control architecture.

  15. Application of torque margin ratios for Eddy Current Dampers

    NASA Astrophysics Data System (ADS)

    Starin, Scott; Rodriguez, Tony

    2003-09-01

    Eddy Current Dampers (ECDs) offer higher robustness, torque capacity and linearity than Fluid Dampers. One of the perceived disadvantages of ECDs when compared to Fluid Dampers is the magnitude of zero speed Coulomb torque. However, the magnitude of total Coulomb torque must be analyzed and considered when applying torque margin ratios, depending on the construction of the ECD and method of reaction torque generation.

  16. Prediction of Large Joint Destruction in Patients With Rheumatoid Arthritis Using 18F-FDG PET/CT and Disease Activity Score

    PubMed Central

    Suto, Takahito; Okamura, Koichi; Yonemoto, Yukio; Okura, Chisa; Tsushima, Yoshito; Takagishi, Kenji

    2016-01-01

    Abstract The assessments of joint damage in patients with rheumatoid arthritis (RA) are mainly restricted to small joints in the hands and feet. However, the development of arthritis in RA patients often involves the large joints, such as the shoulder, elbow, hip, knee, and ankle. Few studies have been reported regarding the degree of large joint destruction in RA patients. 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) visualizes the disease activity in large joints affected by RA. In this study, the associations between destruction of the large joints and the findings of FDG-PET/CT as well as laboratory parameters were investigated, and factors associated with large joint destruction after the administration of biological therapy were identified in RA patients. A total of 264 large joints in 23 RA patients (6 men and 17 women; mean age of 66.9 ± 7.9 years) were assessed in this study. FDG-PET/CT was performed at baseline and 6 months after the initiation of biological therapy. The extent of FDG uptake in large joints (shoulder, elbow, wrist, hip, knee, and ankle) was analyzed using the maximum standardized uptake value (SUVmax). Radiographs of the 12 large joints per patient obtained at baseline and after 2 years were assessed according to Larsen's method. A logistic regression analysis was performed to determine the factors most significantly contributing to the progression of joint destruction within 2 years. Radiographic progression of joint destruction was detected in 33 joints. The SUVmax at baseline and 6 months, and the disease activity score (DAS) 28-erythrocyte sedimentation rate (ESR) at 6, 12, and 24 months were significantly higher in the group with progressive joint destruction. The SUVmax at baseline and DAS28-ESR at 6 months were found to be factors associated with joint destruction at 2 years (P < 0.05). The FDG uptake in the joints with destruction was higher than that observed in the

  17. Learning Dictionaries of Sparse Codes of 3D Movements of Body Joints for Real-Time Human Activity Understanding

    PubMed Central

    Qi, Jin; Yang, Zhiyong

    2014-01-01

    Real-time human activity recognition is essential for human-robot interactions for assisted healthy independent living. Most previous work in this area is performed on traditional two-dimensional (2D) videos and both global and local methods have been used. Since 2D videos are sensitive to changes of lighting condition, view angle, and scale, researchers begun to explore applications of 3D information in human activity understanding in recently years. Unfortunately, features that work well on 2D videos usually don't perform well on 3D videos and there is no consensus on what 3D features should be used. Here we propose a model of human activity recognition based on 3D movements of body joints. Our method has three steps, learning dictionaries of sparse codes of 3D movements of joints, sparse coding, and classification. In the first step, space-time volumes of 3D movements of body joints are obtained via dense sampling and independent component analysis is then performed to construct a dictionary of sparse codes for each activity. In the second step, the space-time volumes are projected to the dictionaries and a set of sparse histograms of the projection coefficients are constructed as feature representations of the activities. Finally, the sparse histograms are used as inputs to a support vector machine to recognize human activities. We tested this model on three databases of human activities and found that it outperforms the state-of-the-art algorithms. Thus, this model can be used for real-time human activity recognition in many applications. PMID:25473850

  18. Learning dictionaries of sparse codes of 3D movements of body joints for real-time human activity understanding.

    PubMed

    Qi, Jin; Yang, Zhiyong

    2014-01-01

    Real-time human activity recognition is essential for human-robot interactions for assisted healthy independent living. Most previous work in this area is performed on traditional two-dimensional (2D) videos and both global and local methods have been used. Since 2D videos are sensitive to changes of lighting condition, view angle, and scale, researchers begun to explore applications of 3D information in human activity understanding in recently years. Unfortunately, features that work well on 2D videos usually don't perform well on 3D videos and there is no consensus on what 3D features should be used. Here we propose a model of human activity recognition based on 3D movements of body joints. Our method has three steps, learning dictionaries of sparse codes of 3D movements of joints, sparse coding, and classification. In the first step, space-time volumes of 3D movements of body joints are obtained via dense sampling and independent component analysis is then performed to construct a dictionary of sparse codes for each activity. In the second step, the space-time volumes are projected to the dictionaries and a set of sparse histograms of the projection coefficients are constructed as feature representations of the activities. Finally, the sparse histograms are used as inputs to a support vector machine to recognize human activities. We tested this model on three databases of human activities and found that it outperforms the state-of-the-art algorithms. Thus, this model can be used for real-time human activity recognition in many applications. PMID:25473850

  19. ACTIVATION OF B-CATENIN SIGNALLING LEADS TO TEMPOROMANDIBULAR JOINT DEFECTS

    PubMed Central

    Wang, M.; Li, S.; Xie, W.; Shen, J.; Im, H-J.; Holz, J.D.; Wang, M.; Diekwisch, T.G.H.; Chen, D.

    2014-01-01

    Despite extensive research in knee and hip osteoarthritis (OA), the underlying mechanism of temporomandibular joint (TMJ) disorder remains largely unknown. The purpose of this study was to determine whether the constitutive activation of β-catenin in the middle and deep layers of the articular cartilage can compromise the homeostasis of this tissue in the TMJ. Co12CreERT2 transgenic mice were bred with RosamT/mG reporter mice to determine Cre recombination efficiency. Co12CreERT2 mice were then crossed with β-cateninflox (ex3)/+ mice to generate β-catenin conditional activation mice, β-catenin(ex3)Co12ER. TMJ samples were harvested when the mice were 1-, 3- or 6-month-old and evaluated using histology, histomorphometry and immunohistochemistry. β-catenin(ex3)Co12ER mice were further crossed with Mmp13flox/flox and Adamts5−/− mice to generate β-catenin(ex3)/Mmp13)Co12ER and β-catenin(ex3)Co12ER)/Adamts5−/− double mutant mice to investigate the role of Mmp13 and Adamts5 in the development of TMJ disorder. High levels of Cre-recombination were seen in Co12CreERT2;RosamT/mG mice. Progressive TMJ defects developed in 1-, 3- and 6-month-old β-catenin(ex3)Co12ER mice, as revealed by histology and histomorphometry. Results further demonstrated that the defects observed in β-catenin(ex3)Co12ER mice were significantly decelerated after deletion of the Mmp13 or Adamts5 gene in (β-catenin(ex3)/Mmp13)co12ER or β-catenin(ex3)Co12ER/ Adamts5−/− double mutant mice. In summary, we found that β-catenin is a critical gene in the induction of TMJ cartilage degeneration, and over-expressing β-catenin in TMJ cartilage leads to defects assembling an OA-like phenotype. Deletion of Mmp13 and Adamts5 in β-catenin(ex3)Co12ER mice ameliorates the development of TMJ defects. This study suggests that Mmp13 and Adamts5 could be potential therapeutic targets for the treatment of TMJ disorders. PMID:25340802

  20. Activation of β-catenin signalling leads to temporomandibular joint defects.

    PubMed

    Wang, M; Li, S; Xie, W; Shen, J; Im, H J; Holz, J D; Wang, M; Diekwisch, T G; Chen, D

    2014-01-01

    Despite extensive research in knee and hip osteoarthritis (OA), the underlying mechanism of temporomandibular joint (TMJ) disorder remains largely unknown. The purpose of this study was to determine whether the constitutive activation of β-catenin in the middle and deep layers of the articular cartilage can compromise the homeostasis of this tissue in the TMJ. Col2CreERT2 transgenic mice were bred with RosamT/mG reporter mice to determine Cre recombination efficiency. Col2CreERT2 mice were then crossed with β-cateninflox(ex3)+ mice to generate β-catenin conditional activation mice, β-catenin(ex3)Col2ER. TMJ samples were harvested when the mice were 1-, 3- or 6-month-old and evaluated using histology, histomorphometry and immunohistochemistry. β-catenin(ex3)Col2ER mice were further crossed with Mmp13flox/flox and Adamts5-/- mice to generate (β-catenin(ex3)/Mmp13)Col2ER and β-catenin(ex3)Col2ER)/Adamts5-/- double mutant mice to investigate the role of Mmp13 and Adamts5 in the development of TMJ disorder. High levels of Cre-recombination were seen in Col2CreERT2;RosamT/mGmice. Progressive TMJ defects developed in 1-, 3- and 6-month-old β-catenin(ex3)Col2ER mice, as revealed by histology and histomorphometry. Results further demonstrated that the defects observed in β-catenin(ex3)Col2ER mice were significantly decelerated after deletion of the Mmp13 or Adamts5 gene in (β-catenin(ex3)/Mmp13)Col2ER or β-catenin(ex3)Col2ER/Adamts5-/- double mutant mice. In summary, we found that β-catenin is a critical gene in the induction of TMJ cartilage degeneration, and over-expressing β-catenin in TMJ cartilage leads to defects assembling an OA-like phenotype. Deletion of Mmp13 and Adamts5 in β-catenin(ex3)Col2ER mice ameliorates the development of TMJ defects. This study suggests that Mmp13 and Adamts5 could be potential therapeutic targets for the treatment of TMJ disorders. PMID:25340802

  1. Microstructure and Performance of Kovar/Alumina Joints Made with Silver-Copper Base Active Metal Braze Alloys

    SciTech Connect

    STEPHENS, JOHN J.; VIANCO,PAUL T.; HLAVA,PAUL F.; WALKER,CHARLES A.

    1999-12-15

    Poor hermeticity performance was observed for Al{sub 2}O{sub 3}-Al{sub 2}O{sub 3} ceramic-ceramic joints having a Kovar{trademark} alloy interlayer. The active Ag-Cu-Ti filler metal was used to braze the substrates together. The Ti active element was scavenged from the filler metal by the formation of a (Fe, Ni, Co){sub x}Ti phase (x= 2-3) that prevented development of a continuous Ti{sub x}O{sub y} layer at the filler metal/Al{sub 2}O{sub 3} interface. Altering the process parameters did not circumvent the scavenging of Ti. Molybdenum barrier layers 1000, 2500, or 5000 {angstrom} thick on the Kovar{trademark} surfaces successfully allowed Ti{sub x}O{sub y} formation at the filler metal/Al{sub 2}O{sub 3} interface and hermetic joints. The problems with the Ag-Cu-Ti filler metal for Kovar{trademark}/Al{sub 2}O{sub 3} braze joints led to the evaluation of a Ag-Cu-Zr filler metal. The Zr (active element) in Ag-Cu-Zr filler metal was not susceptible to the scavenging problem.

  2. Magnetically Torqued Thin Accretion Disks

    NASA Astrophysics Data System (ADS)

    Kluźniak, W.; Rappaport, S.

    2007-12-01

    We compute the properties of a geometrically thin, steady accretion disk surrounding a central rotating, magnetized star. The magnetosphere is assumed to entrain the disk over a wide range of radii. The model is simplified in that we adopt two (alternate) ad hoc, but plausible, expressions for the azimuthal component of the magnetic field as a function of radial distance. We find a solution for the angular velocity profile tending to corotation close to the central star and smoothly matching a Keplerian curve at a radius where the viscous stress vanishes. The value of this ``transition'' radius is nearly the same for both of our adopted B-field models. We then solve analytically for the torques on the central star and for the disk luminosity due to gravity and magnetic torques. When expressed in a dimensionless form, the resulting quantities depend on one parameter alone, the ratio of the transition radius to the corotation radius. For rapid rotators, the accretion disk may be powered mostly by spin-down of the central star. These results are independent of the viscosity prescription in the disk. We also solve for the disk structure for the special case of an optically thick alpha disk. Our results are applicable to a range of astrophysical systems including accreting neutron stars, intermediate polar cataclysmic variables, and T Tauri systems.

  3. Visual Feedback of the Non-Moving Limb Improves Active Joint-Position Sense of the Impaired Limb in Spastic Hemiparetic Cerebral Palsy

    ERIC Educational Resources Information Center

    Smorenburg, Ana R. P.; Ledebt, Annick; Deconinck, Frederik J. A.; Savelsbergh, Geert J. P.

    2011-01-01

    This study examined the active joint-position sense in children with Spastic Hemiparetic Cerebral Palsy (SHCP) and the effect of static visual feedback and static mirror visual feedback, of the non-moving limb, on the joint-position sense. Participants were asked to match the position of one upper limb with that of the contralateral limb. The task…

  4. Effect of Multipass TIG and Activated TIG Welding Process on the Thermo-Mechanical Behavior of 316LN Stainless Steel Weld Joints

    NASA Astrophysics Data System (ADS)

    Ganesh, K. C.; Balasubramanian, K. R.; Vasudevan, M.; Vasantharaja, P.; Chandrasekhar, N.

    2016-04-01

    The primary objective of this work was to develop a finite element model to predict the thermo-mechanical behavior of an activated tungsten inert gas (ATIG)-welded joint. The ATIG-welded joint was fabricated using 10 mm thickness of 316LN stainless steel plates in a single pass. To distinguish the merits of ATIG welding process, it was compared with manual multipass tungsten inert gas (MPTIG)-welded joint. The ATIG-welded joint was fabricated with square butt edge configuration using an activating flux developed in-house. The MPTIG-welded joint was fabricated in thirteen passes with V-groove edge configuration. The finite element model was developed to predict the transient temperature, residual stress, and distortion of the welded joints. Also, microhardness, impact toughness, tensile strength, ferrite measurement, and microstructure were characterized. Since most of the recent publications of ATIG-welded joint was focused on the molten weld pool dynamics, this research work gives an insight on the thermo-mechanical behavior of ATIG-welded joint over MPTIG-welded joint.

  5. Involvement of platelet-activating factor and tumour necrosis factor in the pathogenesis of joint inflammation in rabbits.

    PubMed Central

    Zarco, P; Maestre, C; Herrero-Beaumont, G; González, E; Garcia-Hoyo, R; Navarro, F J; Braquet, P; Egido, J

    1992-01-01

    We have studied the participation of platelet-activating factor (PAF) in antigen-induced arthritis in rabbits, as well as the possible co-operation between PAF and tumour necrosis factor (TNF) in their ability to induce joint inflammation when injected into the knees of healthy rabbits. The administration of two structurally different PAF receptor antagonists, BN52021 and Alprazolam, from 4 h before the intra-articular injection of ovalbumin in preimmunized rabbits, induced an important reduction in the synovial fluid volume, in the amount of cells infiltrating the articular cavity and the synovial membrane, as well as in the prostaglandin E2 (PGE2) concentration. Furthermore, proteoglycans of the articular cartilage, which were found diminished in animals with non-treated arthritis, were well preserved in rabbits treated with PAF antagonists. All the synovial fluids from joints with arthritis had detectable amounts of PAF. The injection of either TNF or PAF into the joints of normal rabbits induced a mild inflammation. When TNF was administered 1 h before PAF, a synergistic response was noted in the synovial fluid volume, in the accumulation of leucocytes, and in the amount of PGE2. The administration of BN50726, a hetrazepine with a potent PAF-receptor antagonist effect, induced a diminution in those parameters. Our results suggest that PAF may be an early and important mediator of joint damage, and that TNF can amplify the inflammatory response induced by PAF. PAF receptor antagonists could play some role in the treatment of inflammatory joint diseases. Images Fig. 2 Fig. 4 PMID:1315229

  6. Current Activities Assessing Butt Fusion Joint Integrity in High Density Polyethylene Piping

    SciTech Connect

    Crawford, Susan L.; Cinson, Anthony D.; Doctor, Steven R.; Denslow, Kayte M.

    2012-09-01

    The Pacific Northwest National Laboratory (PNNL) in Richland, Washington, conducted initial studies to evaluate the effectiveness of nondestructive examinations (NDE) coupled with mechanical testing for assessing butt fusion joint integrity in high density polyethylene (HDPE) pipe. The work provided insightful information to the United States Nuclear Regulatory Commission (NRC) on the effectiveness of volumetric inspection techniques for detecting lack of fusion (LOF) conditions in the fusion joints. HDPE has been installed on a limited basis in American Society of Mechanical Engineers (ASME) Class 3, buried piping systems at several operating U.S. nuclear power plants and has been proposed for use in new construction. A comparison was made between the results from ultrasonic and microwave nondestructive examinations and the results from mechanical destructive evaluations, specifically the high-speed tensile test and the side-bend test, for determining joint integrity. The data comparison revealed that none of the NDE techniques detected all of the lack-of-fusion conditions that were revealed by the destructive tests. Follow-on work has recently been initiated at PNNL to accurately characterize the NDE responses from machined flaws of varying size and location in PE 4710 materials as well as the LOF condition. This effort is directed at quantifying the ability of volumetric NDE techniques to detect flaws in relation to the critical flaw size associated with joint integrity. A status of these latest investigations is presented.

  7. Reduction of phase noise in nanowire spin orbit torque oscillators

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Verba, Roman; Tiberkevich, Vasil; Schneider, Tobias; Smith, Andrew; Duan, Zheng; Youngblood, Brian; Lenz, Kilian; Lindner, Jürgen; Slavin, Andrei N.; Krivorotov, Ilya N.

    2015-11-01

    Spin torque oscillators (STOs) are compact, tunable sources of microwave radiation that serve as a test bed for studies of nonlinear magnetization dynamics at the nanometer length scale. The spin torque in an STO can be created by spin-orbit interaction, but low spectral purity of the microwave signals generated by spin orbit torque oscillators hinders practical applications of these magnetic nanodevices. Here we demonstrate a method for decreasing the phase noise of spin orbit torque oscillators based on Pt/Ni80Fe20 nanowires. We experimentally demonstrate that tapering of the nanowire, which serves as the STO active region, significantly decreases the spectral linewidth of the generated signal. We explain the observed linewidth narrowing in the framework of the Ginzburg-Landau auto-oscillator model. The model reveals that spatial non-uniformity of the spin current density in the tapered nanowire geometry hinders the excitation of higher order spin-wave modes, thus stabilizing the single-mode generation regime. This non-uniformity also generates a restoring force acting on the excited self-oscillatory mode, which reduces thermal fluctuations of the mode spatial position along the wire. Both these effects improve the STO spectral purity.

  8. Reduction of phase noise in nanowire spin orbit torque oscillators

    PubMed Central

    Yang, Liu; Verba, Roman; Tiberkevich, Vasil; Schneider, Tobias; Smith, Andrew; Duan, Zheng; Youngblood, Brian; Lenz, Kilian; Lindner, Jürgen; Slavin, Andrei N.; Krivorotov, Ilya N.

    2015-01-01

    Spin torque oscillators (STOs) are compact, tunable sources of microwave radiation that serve as a test bed for studies of nonlinear magnetization dynamics at the nanometer length scale. The spin torque in an STO can be created by spin-orbit interaction, but low spectral purity of the microwave signals generated by spin orbit torque oscillators hinders practical applications of these magnetic nanodevices. Here we demonstrate a method for decreasing the phase noise of spin orbit torque oscillators based on Pt/Ni80Fe20 nanowires. We experimentally demonstrate that tapering of the nanowire, which serves as the STO active region, significantly decreases the spectral linewidth of the generated signal. We explain the observed linewidth narrowing in the framework of the Ginzburg-Landau auto-oscillator model. The model reveals that spatial non-uniformity of the spin current density in the tapered nanowire geometry hinders the excitation of higher order spin-wave modes, thus stabilizing the single-mode generation regime. This non-uniformity also generates a restoring force acting on the excited self-oscillatory mode, which reduces thermal fluctuations of the mode spatial position along the wire. Both these effects improve the STO spectral purity. PMID:26592432

  9. Changes in neuromuscular function after tasks involving control of EMG versus torque feedback of the same duration.

    PubMed

    Place, Nicolas; Martin, Alain; Lepers, Romuald

    2006-02-01

    This study was designed to compare alterations in neuromuscular function after two tasks of similar duration involving the control of (1) torque level fixed at 40% maximal voluntary contraction (MVC) torque (torque task) and (2) EMG level when exerting 40% MVC torque on the knee extensor muscles. Ten healthy subjects volunteered to participate in two testing sessions separated by approximately 2 h. Contraction duration for the EMG task was fixed for each subject to the time to task failure of the torque task (104+/-20s). MVC, maximal voluntary activation level, muscle compound action potential (M-wave), peak twitch and potentiated peak doublet were assessed before and immediately after each task using electrical stimulation of the femoral nerve. Average EMG activity of quadriceps muscle increased (p<0.01) during the torque task from 27.7+/-5.4% to 46.2+/-19.3% maximal EMG, whereas torque decreased during the EMG task from 41.5+/-2.9% to 28.9+/-3.8% MVC torque. Alterations in MVC torque (p<0.01) and maximal voluntary activation level (p<0.05) were comparable at termination of the two tasks. Rate of perceived exertion was greater (p<0.05) at the end of the torque task compared to the EMG task. Despite the absence of change in the M-wave for either task, potentiated peak doublet was altered after the torque task (-18+/-14%, p<0.01), whereas there was no change after the EMG task (p>0.05). The absence of peripheral failure at the end of the EMG task could be attributed to (1) a lower intramuscular pressure allowing a lesser accumulation of metabolites and (2) a slower rate of PCr hydrolysis compared to the torque task. PMID:16260087

  10. Displaying Force and Torque of A Manipulator

    NASA Technical Reports Server (NTRS)

    Bejczy, A. K.; Dotson, R. S.; Primus, H. C.

    1984-01-01

    Display combines bar charts, vector diagrams, and numerical values to inform operator of forces and torques exerted by end effector of manipulator. On voice or keyboard command, eight-channel strip-chart recorder traces force and torque components and claw position of raw measurements from eight strain gage sensors in end effector. Especially helpful when operator's view of end effector is obscured.

  11. Performance of a constant torque pedal device.

    PubMed Central

    Sherwin, K.

    1979-01-01

    A constant-torque oscillatory pedal-crank device using vertical movement of the feet is described and its performance compared to a conventional rotational cycle. Using a generator to measure the power output the constant-torque device produced 33% less power and thus has no practical value as an alternative to the conventional pedal-crank system. Images Figure 3 PMID:526783

  12. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Engine torque. 25.361 Section 25.361... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Supplementary Conditions § 25.361 Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine...

  13. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Engine torque. 25.361 Section 25.361... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Supplementary Conditions § 25.361 Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine...

  14. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Engine torque. 25.361 Section 25.361... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Supplementary Conditions § 25.361 Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine...

  15. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Engine torque. 25.361 Section 25.361... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Supplementary Conditions § 25.361 Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine...

  16. Radiation Forces and Torques without Stress (Tensors)

    ERIC Educational Resources Information Center

    Bohren, Craig F.

    2011-01-01

    To understand radiation forces and torques or to calculate them does not require invoking photon or electromagnetic field momentum transfer or stress tensors. According to continuum electromagnetic theory, forces and torques exerted by radiation are a consequence of electric and magnetic fields acting on charges and currents that the fields induce…

  17. High-torque power wrench, a concept

    NASA Technical Reports Server (NTRS)

    Cox, E. F.

    1968-01-01

    High-torque power wrench is small enough to be handled by one or two men yet has sufficient torque to remove 1-1/2- to 4-inch nuts from high-pressure tanks and valves. The action can be made automatic by use of solenoid-operated valves and suitable switches.

  18. Forces and torques between nonintersecting straight currents

    NASA Astrophysics Data System (ADS)

    Binder, P.-M.; Cross, Felicity; Silva, J. K.

    2016-07-01

    We analyse two very long current-carrying straight wires that point in arbitrary directions without touching. We find general expressions for the forces and torques for arbitrary points on one wire due to the other. This allows us to make calculations for the overall forces and torques and statements about the stability of parallel and anti-parallel current arrangements.

  19. 14 CFR 25.361 - Engine torque.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 25.361 Section 25.361... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Supplementary Conditions § 25.361 Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine...

  20. Muscle and reflex changes with varying joint angle in hemiparetic stroke

    PubMed Central

    Mirbagheri, Mehdi M; Alibiglou, Laila; Thajchayapong, Montakan; Rymer, William Z

    2008-01-01

    Background Despite intensive investigation, the origins of the neuromuscular abnormalities associated with spasticity are not well understood. In particular, the mechanical properties induced by stretch reflex activity have been especially difficult to study because of a lack of accurate tools separating reflex torque from torque generated by musculo-tendinous structures. The present study addresses this deficit by characterizing the contribution of neural and muscular components to the abnormally high stiffness of the spastic joint. Methods Using system identification techniques, we characterized the neuromuscular abnormalities associated with spasticity of ankle muscles in chronic hemiparetic stroke survivors. In particular, we systematically tracked changes in muscle mechanical properties and in stretch reflex activity during changes in ankle joint angle. Modulation of mechanical properties was assessed by applying perturbations at different initial angles, over the entire range of motion (ROM). Experiments were performed on both paretic and non-paretic sides of stroke survivors, and in healthy controls. Results Both reflex and intrinsic muscle stiffnesses were significantly greater in the spastic/paretic ankle than on the non-paretic side, and these changes were strongly position dependent. The major reflex contributions were observed over the central portion of the angular range, while the intrinsic contributions were most pronounced with the ankle in the dorsiflexed position. Conclusion In spastic ankle muscles, the abnormalities in intrinsic and reflex components of joint torque varied systematically with changing position over the full angular range of motion, indicating that clinical perceptions of increased tone may have quite different origins depending upon the angle where the tests are initiated. Furthermore, reflex stiffness was considerably larger in the non-paretic limb of stroke patients than in healthy control subjects, suggesting that the non

  1. Rotational joint assembly for the prosthetic leg

    NASA Technical Reports Server (NTRS)

    Owens, L. J.; Jones, W. C. (Inventor)

    1977-01-01

    A rotational joint assembly for a prosthetic leg has been devised, which enables an artificial foot to rotate slightly when a person is walking, running or turning. The prosthetic leg includes upper and lower tubular members with the rotational joint assembly interposed between them. The assembly includes a restrainer mechanism which consists of a pivotably mounted paddle element. This device applies limiting force to control the rotation of the foot and also restores torque to return the foot back to its initial position.

  2. Determining the shear fracture properties of HIP joints of reduced-activation ferritic/martensitic steel by a torsion test

    NASA Astrophysics Data System (ADS)

    Nozawa, Takashi; Noh, Sanghoon; Tanigawa, Hiroyasu

    2012-08-01

    Hot isostatic pressing (HIP) is a key technology used to fabricate a first wall with cooling channels for the fusion blanket system utilizing a reduced-activation ferritic/martensitic steel. To qualify the HIPped components, small specimen test techniques are beneficial not only to evaluate the thin-wall cooling channels containing the HIP joint but also to use in neutron irradiation studies. This study aims to develop the torsion test method with special emphasis on providing a reasonable and comprehensive method to determine interfacial shear properties of HIP joints during the torsional fracture process. Torsion test results identified that the torsion process shows yield of the base metal followed by non-elastic deformation due to work hardening of the base metal. By considering this work hardening issue, we propose a reasonable and realistic solution to determine the torsional yield shear stress and the ultimate torsional shear strength of the HIPped interface. Finally, a representative torsion fracture process was identified.

  3. In-line rotating capacitive torque sensor

    DOEpatents

    Kronberg, James W.

    1991-01-01

    A method and apparatus for measuring torques developed along a rotating mechanical assembly comprising a rotating inner portion and a stationary outer portion. The rotating portion has an electrically-conductive flexing section fitted between two coaxial shafts in a configuration which varies radially in accordance with applied torque. The stationary portion comprises a plurality of conductive plates forming a surface concentric with and having a diameter slightly larger than the diameter of the rotating portion. The capacitance between the outer, nonrotating and inner, rotating portion varies with changes in the radial configuration of the rotating portion. Signal output varies approximately linearly with torque for small torques, nonlinearly for larger torques. The sensor is preferably surrounded by a conductive shell to minimize electrical interference from external sources.

  4. In-line rotating capacitive torque sensor

    DOEpatents

    Kronberg, J.W.

    1991-09-10

    Disclosed are a method and apparatus for measuring torques developed along a rotating mechanical assembly comprising a rotating inner portion and a stationary outer portion. The rotating portion has an electrically-conductive flexing section fitted between two coaxial shafts in a configuration which varies radially in accordance with applied torque. The stationary portion comprises a plurality of conductive plates forming a surface concentric with and having a diameter slightly larger than the diameter of the rotating portion. The capacitance between the outer, nonrotating and inner, rotating portion varies with changes in the radial configuration of the rotating portion. Signal output varies approximately linearly with torque for small torques, nonlinearly for larger torques. The sensor is preferably surrounded by a conductive shell to minimize electrical interference from external sources. 18 figures.

  5. RADIOACTIVE MATERIAL PACKAGING TORQUE REQUIREMENTS COMPLIANCE

    SciTech Connect

    Watkins, R.; Leduc, D.

    2011-03-24

    Shipping containers used to transport radioactive material (RAM) in commerce employ a variety of closure mechanisms. Often, these closure mechanisms require a specific amount of torque be applied to a bolt, nut or other threaded fastener. It is important that the required preload is achieved so that the package testing and analysis is not invalidated for the purpose of protecting the public. Torque compliance is a means of ensuring closure preload, is a major factor in accomplishing the package functions of confinement/containment, sub-criticality, and shielding. This paper will address the importance of applying proper torque to package closures, discuss torque value nomenclature, and present one methodology to ensure torque compliance is achieved.

  6. Estimating Torque Imparted on Spacecraft Using Telemetry

    NASA Technical Reports Server (NTRS)

    Lee, Allan Y.; Wang, Eric K.; Macala, Glenn A.

    2013-01-01

    There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of the spacecraft, known drag coefficient of objects in free-molecular flow, and the spacecraft velocity relative to the moon. The density estimated in this way could be used to check results measured by science instruments. Since the proposed methodology could estimate disturbance torque as small as 0.02 N-m, it could also be used to estimate disturbance torque imparted on the spacecraft during high-altitude flybys.

  7. Spin-transfer torques in helimagnets

    NASA Astrophysics Data System (ADS)

    Hals, Kjetil M. D.; Brataas, Arne

    2013-05-01

    We theoretically investigate current-induced magnetization dynamics in chiral-lattice helimagnets. Spin-orbit coupling in noncentrosymmetric crystals induces a reactive spin-transfer torque that has not been previously considered. We demonstrate how the torque is governed by the crystal symmetry and acts as an effective magnetic field along the current direction in cubic B20-type crystals. The effects of the new torque are computed for current-induced dynamics of spin spirals and the Doppler shift of spin waves. In current-induced spin-spiral motion, the new torque tilts the spiral structure. The spin waves of the spiral structure are initially displaced by the new torque, while the dispersion relation is unaffected.

  8. Serratus Anterior and Lower Trapezius Muscle Activities During Multi-Joint Isotonic Scapular Exercises and Isometric Contractions

    PubMed Central

    Tsuruike, Masaaki; Ellenbecker, Todd S.

    2015-01-01

    Context: Proper scapular function during humeral elevation, such as upward rotation, external rotation, and posterior tilting of the scapula, is necessary to prevent shoulder injury. However, the appropriate intensity of rehabilitation exercise for the periscapular muscles has yet to be clarified. Objective: To identify the serratus anterior, lower trapezius, infraspinatus, and posterior deltoid muscle activities during 2 free-motion exercises using 3 intensities and to compare these muscle activities with isometric contractions during quadruped shoulder flexion and external rotation and abduction of the glenohumeral joint. Design: Cross-sectional study. Setting: Health Science Laboratory. Patients or Other Participants: A total of 16 uninjured, healthy, active, male college students (age = 19.5 ± 1.2 years, height = 173.1 ± 6.5 cm, weight = 68.8 ± 6.6 kg). Main Outcome Measure(s): Mean electromyographic activity normalized by the maximal voluntary isometric contraction was analyzed across 3 intensities and 5 exercises. Intraclass correlation coefficients were calculated for electromyographic activity of the 4 muscles in each free-motion exercise. Results: Significant interactions in electromyographic activity were observed between intensities and exercises (P < .05). The quadruped shoulder-flexion exercise activated all 4 muscles compared with other exercises. Also, the modified robbery free-motion exercise activated the serratus anterior, lower trapezius, and infraspinatus compared with the lawn-mower free-motion exercise. However, neither exercise showed a difference in posterior deltoid electromyographic activity. Conclusions: Three intensities exposed the nature of the periscapular muscle activities across the different exercises. The free-motion exercise in periscapular muscle rehabilitation may not modify serratus anterior, lower trapezius, and infraspinatus muscle activities unless knee-joint extension is limited. PMID:25689561

  9. Total joint replacement: A multiple risk factor analysis of physical activity level 1-2 years postoperatively.

    PubMed

    Paxton, Elizabeth W; Torres, Andy; Love, Rebecca M; Barber, Thomas C; Sheth, Dhiren S; Inacio, Maria C S

    2016-07-01

    Background and purpose - The effect of total joint arthroplasty (TJA) on physical activity is not fully understood. We investigated the change in physical activity after TJA and patient factors associated with change. Patients and methods - Using a total joint replacement registry, primary total hip arthroplasty (THA) patients (n = 5,678) and knee arthroplasty (TKA) patients (n = 11,084) between January 1, 2010 and December 31, 2012 were identified. Median age at THA was 68 and median age at TKA was 67. Change in self-reported physical activity (minutes per week) from before TJA (within 1 year of surgery) to after TJA (1-2 years) was the outcome of interest. Patient demographics and comorbidities were evaluated as risk factors. Multiple linear regression was used. Results - Median physical activity before surgery was 50 min/week (IQR: 0-140) for THA patients and 58 (IQR: 3-143) for TKA patients. Median physical activity after surgery was 150 min/week (IQR: 60-280) for both THA patients and TKA patients. Following TJA, 50% of patients met CDC/WHO physical activity guideline criteria. Higher body mass index was associated with lower change in physical activity (THA: -7.1 min/week; TKA: -5.9 min/week). Females had lower change than males (THA: -11 min/week; TKA: -9.1 min/week). In TKA patients, renal failure was associated with lower change (-17 min/week), as were neurological disorders (-30 min/week). Interpretation - Self-reported minutes of physical activity increased from before to after TJA, but 50% of TJA patients did not meet recommended physical activity guideline criteria. Higher body mass index, female sex, and specific comorbidities were found to be associated with low change in physical activity. Patient education on the benefits of physical activity should concentrate on these subgroups of patients. PMID:27299567

  10. Torque teno virus (TTV): current status.

    PubMed

    Hino, Shigeo; Miyata, Hironori

    2007-01-01

    Torque teno virus (TTV), currently classified into the family Circoviridae, genus Anellovirus, was first found in a patient with non-A-E hepatitis. TTV has a single stranded circular DNA of approximately 3.8 kb. TTVs are extraordinarily diverse, spanning five groups including SANBAN and SEN viruses. Torque teno mini virus (TTMV) with approximately 2.9 kb genome also has wide variants. Recently, two related 2.2- and 2.6-kb species joined this community. Recombinations between variants are frequent. This extensive TTV diversity remains unexplained; it is unclear how TTVs could be viable, and why they require such genetic variation. An unequivocal culture system is still not available. TTVs are ubiquitous in > 90% of adults worldwide but no human pathogenicity of TTV has been fully established. Epidemiological surveys need to specify the variants being studied and clinical targets, and must calibrate the sensitivity of the assay used. Potentially interesting observations include a higher viral load in patients with severe idiopathic inflammatory myopathies, cancer and lupus. Active replication was also found in infants with acute respiratory diseases. TTV/TTMV-related viruses were found in chimpanzees, apes, African monkeys and tupaias, and also in chickens, pigs, cows, sheep and dogs. Experimentally, rhesus monkeys were persistently infected by TTV, but only 1/53 chimpanzees. TTV transcribes three species of mRNAs, 3.0-, 1.2- and 1.0-kb in the ratio of 60:5:35. Recently, at least three mRNAs were shown in chicken anaemia virus. The genomic region -154/-76 contains a critical promoter. TTV seems to have at least three proteins; however, the definite functions of these proteins await further research work. PMID:17146841

  11. The Joint Action of Sesquiterpene Lactones from Leaves as an Explanation for the Activity of Cynara cardunculus.

    PubMed

    Rial, Carlos; García, Benito F; Varela, Rosa M; Torres, Ascensión; Molinillo, José M G; Macías, Francisco A

    2016-08-24

    The work described herein is a continuation of a previous study centered on the bioprospect of cardoon (Cynara cardunculus) leaf extracts through the isolation of secondary metabolites with phytotoxic activity. Chromatographic fractionations of the ethyl acetate extract and spectroscopic analysis showed that the majority of the components were sesquiterpene lactones. Of these compounds, aguerin B, grosheimin, and cynaropicrin were very active on etiolated wheat coleoptile, standard target species, and weed growth. The joint action of binary mixtures of these three active sesquiterpene lactones and one nonactive compound (11,13-dihydroxy-8-desoxygrosheimin) was studied. The activities of fixed-ratio mixtures were assessed on wheat coleoptile. The results can be interpreted with respect to a reference model by considering dose-response analyses and isobolograms with linear regression analyses. A total of 17 binary mixtures at different levels of inhibition (ED25, ED50, and ED75) were studied, and predominantly they responded additively (25). Deviations from additivity included seven synergistic responses and two antagonistic responses. The joint action of major sesquiterpene lactones isolated from C. cardunculus can explain the activities observed in extracts and fractions. The results reported here reiterate the utility of the wheat coleoptile bioassay as a quick tool to detect potential synergistic effects in binary mixtures. PMID:27487046

  12. Effects of Nordic walking on pelvis motion and muscle activities around the hip joints of adults with hip osteoarthritis

    PubMed Central

    Homma, Daisuke; Jigami, Hirofumi; Sato, Naritoshi

    2016-01-01

    [Purpose] Increased compensatory pelvic movement is remarkable in limping patients with hip osteoarthritis (OA). However, a method of improving limping has not been established. The purpose of this study was to identify the effects of two types of Nordic walking by analyzing the pelvic movement and muscle activities of adults with hip OA. [Subjects and Methods] Ten patients with OA of the hip performed Japanese-style Nordic walking (JS NW), European-style Nordic walking (ES NW), and Ordinary walking (OW), and the muscle activities around the hip joint and pelvic movements were analyzed. [Results] The pelvic rotation angle was significantly larger in ES NW than in JS NW. In the stance phase, hip abductor muscle activity was significantly decreased in JS NW compared to both OW and ES NW. In the swing phase, rectus abdominis muscle activity was significantly increased in both JS NW and ES NW compared to OW and lumbar erector spinae activity was significantly lower in JS NW than in OW. [Conclusion] JS NW style may reduce the compensatory pelvic rotation in patients with hip OA. JS NW might be better for joint protection and prevention of secondary disorders of the hip in OA patients. PMID:27190455

  13. Analysis and testing of a space crane articulating joint testbed

    NASA Technical Reports Server (NTRS)

    Sutter, Thomas R.; Wu, K. Chauncey

    1992-01-01

    The topics are presented in viewgraph form and include: space crane concept with mobile base; mechanical versus structural articulating joint; articulating joint test bed and reference truss; static and dynamic characterization completed for space crane reference truss configuration; improved linear actuators reduce articulating joint test bed backlash; 1-DOF space crane slew maneuver; boom 2 tip transient response finite element dynamic model; boom 2 tip transient response shear-corrected component modes torque driver profile; peak root member force vs. slew time torque driver profile; and open loop control of space crane motion.

  14. Effect of Activated Flux on the Microstructure, Mechanical Properties, and Residual Stresses of Modified 9Cr-1Mo Steel Weld Joints

    NASA Astrophysics Data System (ADS)

    Maduraimuthu, V.; Vasudevan, M.; Muthupandi, V.; Bhaduri, A. K.; Jayakumar, T.

    2012-02-01

    A novel variant of tungsten inert gas (TIG) welding called activated-TIG (A-TIG) welding, which uses a thin layer of activated flux coating applied on the joint area prior to welding, is known to enhance the depth of penetration during autogenous TIG welding and overcomes the limitation associated with TIG welding of modified 9Cr-1Mo steels. Therefore, it is necessary to develop a specific activated flux for enhancing the depth of penetration during autogeneous TIG welding of modified 9Cr-1Mo steel. In the current work, activated flux composition is optimized to achieve 6 mm depth of penetration in single-pass TIG welding at minimum heat input possible. Then square butt weld joints are made for 6-mm-thick and 10-mm-thick plates using the optimized flux. The effect of flux on the microstructure, mechanical properties, and residual stresses of the A-TIG weld joint is studied by comparing it with that of the weld joints made by conventional multipass TIG welding process using matching filler wire. Welded microstructure in the A-TIG weld joint is coarser because of the higher peak temperature in A-TIG welding process compared with that of multipass TIG weld joint made by a conventional TIG welding process. Transverse strength properties of the modified 9Cr-1Mo steel weld produced by A-TIG welding exceeded the minimum specified strength values of the base materials. The average toughness values of A-TIG weld joints are lower compared with that of the base metal and multipass weld joints due to the presence of δ-ferrite and inclusions in the weld metal caused by the flux. Compressive residual stresses are observed in the fusion zone of A-TIG weld joint, whereas tensile residual stresses are observed in the multipass TIG weld joint.

  15. Activation of V(D)J Recombination Induces the Formation of Interlocus Joints and Hybrid Joints in scid Pre-B-Cell Lines

    PubMed Central

    Lew, Sandra; Franco, Daniel; Chang, Yung

    2000-01-01

    V(D)J recombination is the mechanism by which antigen receptor genes are assembled. The site-specific cleavage mediated by RAG1 and RAG2 proteins generates two types of double-strand DNA breaks: blunt signal ends and covalently sealed hairpin coding ends. Although these DNA breaks are mainly resolved into coding joints and signal joints, they can participate in a nonstandard joining process, forming hybrid and open/shut joints that link coding ends to signal ends. In addition, the broken DNA molecules excised from different receptor gene loci could potentially be joined to generate interlocus joints. The interlocus recombination process may contribute to the translocation between antigen receptor genes and oncogenes, leading to malignant transformation of lymphocytes. To investigate the underlying mechanisms of these nonstandard recombination events, we took advantage of recombination-inducible cell lines derived from scid homozygous (s/s) and scid heterozygous (s/+) mice by transforming B-cell precursors with a temperature-sensitive Abelson murine leukemia virus mutant (ts-Ab-MLV). We can manipulate the level of recombination cleavage and end resolution by altering the cell culture temperature. By analyzing various recombination products in scid and s/+ ts-Ab-MLV transformants, we report in this study that scid cells make higher levels of interlocus and hybrid joints than their normal counterparts. These joints arise concurrently with the formation of intralocus joints, as well as with the appearance of opened coding ends. The junctions of these joining products exhibit excessive nucleotide deletions, a characteristic of scid coding joints. These data suggest that an inability of scid cells to promptly resolve their recombination ends exposes the ends to a random joining process, which can conceivably lead to chromosomal translocations. PMID:10982833

  16. PREFACE: The Science of Making Torque from Wind 2012

    NASA Astrophysics Data System (ADS)

    2014-12-01

    The European Academy of Wind Energy (eawe) was pleased to announce its 4th scientific conference The Science of Making Torque from Wind. Predecessors have successfully been arranged in Delft, The Netherlands (2004), Lyngby, Denmark (2007) and Heraklion, Greece (2010). During the years the Torque Conference has established itself as Europe's leading scientific wind energy conference. The 2012 edition had been organized in the same tradition. More than 300 experts from academia and industry discussed the latest results and developments in fundamental and applied wind energy research, making this Science of Making Torque from Wind conference the largest one to that date. The seven keynote lectures provided the delegates with a unique overview on the state-of-the-art of science and technology. In over twenty sessions the participants discussed the most recent results in wind energy research. From numerical models to sophisticated experiments, from flow optimizations to structural designs, the numerous presentations covered a huge spectrum of ongoing scientific activities. The proceedings of the Torque 2012 combine the 110 papers that have passed the review process. We would like to thank all those who have been involved in organizing the conference and putting together these proceedings, including keynote speakers, session chairs and the enormous amount of reviewers involved. We are especially grateful to Gijs van Kuik for his untiring support. We also deeply appreciate the logistical support and technical services of the University of Oldenburg and the financial support of the State of Lower Saxony. At IOP we would like to thank Anete Ashton for her continuous encouraging support. We are looking forward to all future Torque Conferences, offering an excellent platform for the exchange of the latest and greatest scientific developments in the field of wind energy. Oldenburg, Germany, October 2014 Elke Seidel, Detlev Heinemann, Martin Kühn, Joachim Peinke and Stephan

  17. Passive torque wrench and angular position detection using a single-beam optical trap.

    PubMed

    Inman, James; Forth, Scott; Wang, Michelle D

    2010-09-01

    The recent advent of angular optical trapping techniques has allowed for rotational control and direct torque measurement on biological substrates. Here we present a method that increases the versatility and flexibility of these techniques. We demonstrate that a single beam with a rapidly rotating linear polarization can be utilized to apply a constant controllable torque to a trapped particle without active feedback, while simultaneously measuring the particle angular position. In addition, this device can rapidly switch between a torque wrench and an angular trap. These features should make possible torsional measurements across a wide range of biological systems. PMID:20808379

  18. In vitro activity of tedizolid against staphylococci isolated from prosthetic joint infections.

    PubMed

    Schmidt-Malan, Suzannah M; Greenwood Quaintance, Kerryl E; Karau, Melissa J; Patel, Robin

    2016-05-01

    We determined the MIC and minimum biofilm bactericidal concentration (MBBC) of tedizolid and vancomycin against 97 isolates of Staphylococcus aureus and 74 isolates of Staphylococcus epidermidis associated with prosthetic joint infection. All isolates were vancomycin susceptible in the planktonic state; all staphylococci studied had a tedizolid MIC ≤0.5 μg/mL. The MBBC90 was >32 and >128 μg/mL for tedizolid and vancomycin, respectively. PMID:26906190

  19. Stable computed-torque control of robot manipulators via fuzzy self-tuning.

    PubMed

    Llama, M A; Kelly, R; Santibanez, V

    2000-01-01

    Computed-torque control is a well-known motion control strategy for manipulators which ensures global asymptotic stability for fixed symmetric positive definite (proportional and derivative) gain matrices. In this paper, we show that global asymptotic stability also holds for a class of gain matrices depending on the manipulator state. This feature increases the potential of the computed-torque control scheme to handle practical constraint in actual robots such as presence of friction in the joints and actuators with limited torque capabilities. We illustrate this potential by means of a fuzzy self-tuning algorithm to select the proportional and derivative gains according to the actual tracking position error. Experiments on a two degrees of freedom robot arm show the usefulness of the proposed approach. PMID:18244736

  20. Feasible muscle activation ranges based on inverse dynamics analyses of human walking.

    PubMed

    Simpson, Cole S; Sohn, M Hongchul; Allen, Jessica L; Ting, Lena H

    2015-09-18

    Although it is possible to produce the same movement using an infinite number of different muscle activation patterns owing to musculoskeletal redundancy, the degree to which observed variations in muscle activity can deviate from optimal solutions computed from biomechanical models is not known. Here, we examined the range of biomechanically permitted activation levels in individual muscles during human walking using a detailed musculoskeletal model and experimentally-measured kinetics and kinematics. Feasible muscle activation ranges define the minimum and maximum possible level of each muscle's activation that satisfy inverse dynamics joint torques assuming that all other muscles can vary their activation as needed. During walking, 73% of the muscles had feasible muscle activation ranges that were greater than 95% of the total muscle activation range over more than 95% of the gait cycle, indicating that, individually, most muscles could be fully active or fully inactive while still satisfying inverse dynamics joint torques. Moreover, the shapes of the feasible muscle activation ranges did not resemble previously-reported muscle activation patterns nor optimal solutions, i.e. static optimization and computed muscle control, that are based on the same biomechanical constraints. Our results demonstrate that joint torque requirements from standard inverse dynamics calculations are insufficient to define the activation of individual muscles during walking in healthy individuals. Identifying feasible muscle activation ranges may be an effective way to evaluate the impact of additional biomechanical and/or neural constraints on possible versus actual muscle activity in both normal and impaired movements. PMID:26300401

  1. Evaluating quality of adhesive joints in glass-fiber plastic piping by using active thermal NDT

    NASA Astrophysics Data System (ADS)

    Grosso, M.; Marinho, C. A.; Nesteruk, D. A.; Rebello, J. M.; Soares, S. D.; Vavilov, V. P.

    2013-05-01

    GRP-type composites (Glass-fibre Reinforced Plastics) have been continuously employed in the oil industry in recent years, often on platforms, especially in pipes for water or oil under moderate temperatures. In this case, the pipes are usually connected through adhesive joints and, consequently, the detection of defects in these joints, as areas without adhesive or adhesive failure (disbonding), gains great importance. One-sided inspection on the joint surface (front side) is a challenging task because the material thickness easily exceeds 10 mm that is far beyond the limits of the capacity of thermography applied to GRP inspection, as confirmed by the experience. Detection limits have been evaluated both theoretically and experimentally as a function of outer wall thickness and defect lateral size. The 3D modeling was accomplished by using the ThermoCalc-6L software. The experimental unit consisted of a FLIR SC640 and NEC TH- 9100 IR imagers and some home-made heaters with the power from 1,5 to 30 kW. The results obtained by applying pulsed heating have demonstrated that the inspection efficiency is strongly dependent on the outer wall thickness with a value of about 8 mm being a detection limit.

  2. Establishment of a rat model of lumbar facet joint osteoarthritis using intraarticular injection of urinary plasminogen activator.

    PubMed

    Shuang, Feng; Hou, Shu-Xun; Zhu, Jia-Liang; Liu, Yan; Zhou, Ying; Zhang, Chun-Li; Tang, Jia-Guang

    2015-01-01

    Lumbar facet joint (LFJ) osteoarthritis (OA) is an important etiology of low back pain. Several animal models of LFJ OA have been established using intraarticular injection of various chemicals. This study aimed to establish a rat model of LFJ OA using urinary plasminogen activator (uPA). Sprague-Dawley rats were treated with intraarticular injection in the L5-L6 facet joints with uPA (OA group, n = 40) or normal saline (vehicle group, n = 40). Mechanical and thermal hyperalgesia in the ipsilateral hind paws were evaluated using von Frey hairs and a thermoalgesia instrument, respectively. Toluidine blue staining, hematoxylin-eosin staining, and immunohistochemical examination of the LFJ was performed. Treatment with uPA induced cartilage damage, synovitis, and proliferation of synovial cells in the fact joints. The OA group showed significantly higher hyperalgesia in the hind paws in comparison with the vehicle group and normal controls (P < 0.05). Expression of IL-1β, TNF-α, and iNOS in the LFJ cartilage in the OA group was significantly increased (P < 0.05). A rat model of LFJ OA was successfully established using intraarticular injection of uPA. This animal model is convenient and shows good resemblance to human OA pathology. PMID:25892493

  3. Torque Ripple Reduction of Reluctance Torque Assisted Motors Using Asymmetric Flux Barriers

    NASA Astrophysics Data System (ADS)

    Hiramoto, Kenji; Takeda, Yoji; Sanada, Masayuki; Morimoto, Shigeo

    Interior permanent magnet synchronous motor (IPMSM) is efficient and can be operated in wide speed region; therefore it is used widely. However, torque ripple of reluctance torque assisted motors, for example IPMSM and synchronous reluctance motor (SynRM), is very large. The skew is known in the prior art as a torque ripple reduction method of AC motors. Although the skew is effective for torque ripple reduction, structure is complicated and it has the disadvantage that average torque will decrease. The discontinuous variation of magnetic resistance between flux barriers and teeth cause the torque ripple. In this paper, in order to ease the discontinuous variation of magnetic resistance, flux barriers are asymmetrically designed so that the relative position relation between flux barriers and teeth may not be in agreement as much as possible. As a result, the torque ripple can be reduced dramatically without the average torque decrease. The experimental motor has been fabricated and the results of measuring torque ripple prove the validity of the torque ripple reduction using asymmetric flux barriers.

  4. Research on new dynamic torque calibration system

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Wang, Zhong Yu; Yin, Xiao

    2016-06-01

    Dynamic torque calibration method based on rotating table and interferometric system is studied in this paper. A load mass with certain moment of inertia are screwed on the top of torque transducer, the dynamic torque is realized by load object are traceable to angular acceleration and moment of inertia of the object by M (t)=I θ ¨(t) , where I is the total moment of inertia acting on the sensing element of the torque transducer and θ ¨ is the time and spatial-dependent angular acceleration of the load object which is directly measured by a laser interferometer. This paper will introduce a dynamic torque calibration system developed at Changcheng Institute of Metrology and Measurement (CIMM). It uses servomotor to generate dynamic torque in the range from 0.1Nm to 200Nm, and heterodyne laser interferometers cooperated with column grating are used for angular acceleration measurement. An airbearing system is developed to increase the performance of the dynamic turque calibration system. This paper introduce the setup of the dynamic torque calibration system.

  5. Torque exerted on the side of crustal blocks controls the kinematics of Ethiopian Rift

    NASA Astrophysics Data System (ADS)

    Muluneh, Ameha A.; Kidane, Tesfaye; Cuffaro, Marco; Doglioni, Carlo

    2016-04-01

    Plate tectonic stress at active plate boundary can arises from 1) a torque applied on the side of lithospheric blocks and 2) a torque at the base of the lithosphere due to the flow of the underlying mantle. In this paper we use a simple force balance analysis to compare side and basal shear stresses and their contribution in driving kinematics and deformation in the Ethiopian Rift (ER), in the northern part of the East African Rift System (EARS). Assuming the constraints of the ER given by the dimension of the lithospheric blocks, the strain rate, the viscosity of the low velocity zone (LVZ) and the depth of the brittle-ductile transition zone, the lateral torque is several orders of magnitude higher than the basal torque. The minor contribution of basal torque might be due to low viscosity in the LVZ. Both Africa and Somalia plates are moving to the "west" relative to the mantle and there are not slabs that can justify this pull and consequent motion. Therefore, we invoke that westerly oriented tidal torque on Africa and Somalia plates in providing the necessary side torque in the region. This plate motion predicts significant sinistral transtension along the ER and rift parallel strike-slip faulting similar to the estimated angular velocity vector for tectonic blocks and GPS observations. Vertical axis block rotations are observed in areas where the lithospheric mantle is removed and strain is widely distributed.

  6. Setting tool with retractable torque fingers

    SciTech Connect

    Nevels, D.L.; Baugh, J.L.

    1986-07-08

    A method is described of setting a liner in a well bore using a setting tool of the type adapted to be made up in a pipe string for releasably engaging a setting sleeve in a well bore, comprising the steps of: connecting a mandrel in the pipe string which has a setting nut with external connecting threads for engaging mating connecting threads located on the interior of a setting sleeve disposed about the mandrel, the mandrel being slidably disposed within the setting nut when the setting nut is engaging the setting sleeve, the mandrel being slidable between an extended, running-in position and a weight set-down position; mounting a torque collar on the mandrel exterior, the torque collar having at least one torque finger mounted thereon which is axially slidable on an external surface of the torque collar in a plane which is parallel to the longitudinal axis of the tool, the setting sleeve having at least one end notch adapted to receive the axially slidable torque finger; initially latching the mandrel to the setting sleeve with each torque finger received within its respective end notch; setting weight down on the pipe string from the well surface to release the latch and allow relative movement between the connecting threads of the setting nut and setting sleeve; applying right hand torque to the pipe string to release the connecting threads of the setting nut from the setting sleeve; temporarily lifting the pipe string and setting tool to test the disengagement of the setting nut; again resting the setting tool on the setting sleeve; rotating the pipe string to realign the torque finger and the setting sleeve end notch and reengage the torque finger with the end notch; and continuing to rotate to the right to rotate the setting sleeve during subsequent well bore operations.

  7. Torquing preload in a lubricated bolt

    NASA Technical Reports Server (NTRS)

    Seegmiller, H. L.

    1978-01-01

    The tension preload obtained by torquing a 7/8 in. diam UNC high strength bolt was determined for lubricated and dry conditions. Consistent preload with a variation of + or - 3% was obtained when the bolt head area was lubricated prior to each torque application. Preload tensions nearly 70% greater than the value predicted with the commonly used formula occurred with the lubricated bolt. A reduction to 39% of the initial preload was observed during 50 torque applications without relubrication. Little evidence of wear was noted after 203 cycles of tightening.

  8. Electromagnetic Torque in Tokamaks with Toroidal Asymmetries

    NASA Astrophysics Data System (ADS)

    Logan, Nikolas Christopher

    Toroidal rotation and rotation shear strongly influences stability and confinement in tokamaks. Breaking of the toroidal symmetry by fields orders of magnitude smaller than the axisymmetric field can, however, produce electromagnetic torques that significantly affect the plasma rotation, stability and confinement. These electromagnetic torques are the study of this thesis. There are two typical types of electromagnetic torques in tokamaks: 1) "resonant torques" for which a plasma current defined by a single toroidal and single poloidal harmonic interact with external currents and 2) "nonresonant torques" for which the global plasma response to nonaxisymmetric fields is phase shifted by kinetic effects that drive the rotation towards a neoclassical offset. This work describes the diagnostics and analysis necessary to evaluate the torque by measuring the rate of momentum transfer per unit area in the vacuum region between the plasma and external currents using localized magnetic sensors to measure the Maxwell stress. These measurements provide model independent quantification of both the resonant and nonresonant electromagnetic torques, enabling direct verification of theoretical models. Measured values of the nonresonant torque are shown to agree well with the perturbed equilibrium nonambipolar transport (PENT) code calculation of torque from cross field transport in nonaxisymmetric equilibria. A combined neoclassical toroidal viscosity (NTV) theory, valid across a wide range of kinetic regimes, is fully implemented for the first time in general aspect ratio and shaped plasmas. The code captures pitch angle resonances, reproducing previously inaccessible collisionality limits in the model. The complete treatment of the model enables benchmarking to the hybrid kinetic MHD stability codes MARS-K and MISK, confirming the energy-torque equivalency principle in perturbed equilibria. Experimental validations of PENT results confirm the torque applied by nonaxisymmetric

  9. Differences in the impact of the frequency and enjoyment of joint family activities on adolescent substance use and violence.

    PubMed

    Windlin, Béat; Kuntsche, Emmanuel

    2012-05-01

    Previous research has concentrated exclusively on the association between the frequency of joint family activities (JFA) and adolescent problem behaviours. In this study, multiple linear regressions based on a national sample of 3467 13- to 16-year-olds in Switzerland revealed that JFA enjoyment rather than JFA frequency is consistently related to low adolescent substance use and violence. By choosing JFA that their children enjoy, parents might provide opportunities for disclosure, strengthen family bonds and reduce the likelihood of adolescent problem behaviours. In terms of prevention, a shift in focus towards the quality rather than the quantity of JFA could prove more effective. PMID:21963683

  10. Co-operation at work: a process-oriented perspective on joint activity in inter-organizational relations.

    PubMed

    Wehner, T; Clases, C; Bachmann, R

    2000-07-01

    In this paper the authors present a conceptual framework for analysing co-operation between organizations as a situated process, highlighting co-operation, co-ordination and co-construction as different modes of joint activity. Within this framework, the analysis of unexpected events becomes a crucial issue. The analytic power of reconstructing the (psycho-) logics of unexpected events in inter-organizational relations will be demonstrated in the presentation of selected outcomes of a research project on the dynamics of producer-supplier relationships in the German automobile industry. Also in this empirical part, the significance of trust and confidence in inter-organizational relations will be reflected. PMID:10929832

  11. Reusable Solid Rocket Motor Nozzle Joint 5 Redesign

    NASA Technical Reports Server (NTRS)

    Lui, R. C.; Stratton, T. C.; LaMont, D. T.

    2003-01-01

    Torque tension testing of a newly designed Reusable Solid Rocket Motor nozzle bolted assembly was successfully completed. Test results showed that the 3-sigma preload variation was as expected at the required input torque level and the preload relaxation were within the engineering limits. A shim installation technique was demonstrated as a simple process to fill a shear lip gap between nozzle housings in the joint region. A new automated torque system was successfully demonstrated in this test. This torque control tool was found to be very precise and accurate. The bolted assembly performance was further evaluated using the Nozzle Structural Test Bed. Both current socket head cap screw and proposed multiphase alloy bolt configurations were tested. Results indicated that joint skip and bolt bending were significantly reduced with the new multiphase alloy bolt design. This paper summarizes all the test results completed to date.

  12. Influence of the implant-abutment connection design and diameter on the screw joint stability

    PubMed Central

    Shin, Hyon-Mo; Huh, Jung-Bo; Yun, Mi-Jeong; Jeon, Young-Chan; Chang, Brian Myung

    2014-01-01

    PURPOSE This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. MATERIALS AND METHODS Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (α=0.05). RESULTS The postload removal torque value was high in the following order with regard to magnitude: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). CONCLUSION The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate. PMID:24843398

  13. Enhancement of antidepressant-like activity by joint administration of imipramine and magnesium in the forced swim test: Behavioral and pharmacokinetic studies in mice.

    PubMed

    Poleszak, Ewa; Wlaź, Piotr; Szewczyk, Bernadeta; Kedzierska, Ewa; Wyska, Elzbieta; Librowski, Tadeusz; Szymura-Oleksiak, Joanna; Fidecka, Sylwia; Pilc, Andrzej; Nowak, Gabriel

    2005-07-01

    The effect of joint administration of imipramine (IMI) and magnesium (Mg) on antidepressant-like activity was studied in mice using forced swim test (FST). Mg doses ineffective per se (5 and 10 mg/kg) given jointly with IMI also at ineffective doses (10 and 15 mg/kg) resulted in a potent reduction in the immobility time. Since these combined treatments did not influence locomotor activity, the antidepressant-like activity was not due to non-specific behavioral activation. Moreover, we estimated the effect of joint administration of magnesium and IMI in FST on serum and brain magnesium, IMI and its active metabolite desipramine (DMI) concentrations in mice. Swim stress (mice subjected to FST) increased the magnesium concentration in serum and decreased it in the brain compared to naive animals. Moreover administration of IMI increased (normalized) magnesium brain concentration, without influence on the serum level. Joint administration of IMI and magnesium did not influence magnesium (compared with FST) or IMI and DMI (compared with IMI treatment alone) concentrations in both examined tissues. The present data demonstrated an enhancement of the antidepressant-like effect by joint administration of IMI and magnesium in the FST, and further indicate the particular role of magnesium in the antidepressant action. Since there was no increase in IMI, DMI or magnesium concentration after joint administration of magnesium and IMI, the data suggest that pharmacodynamic rather than pharmacokinetic interaction between magnesium and IMI is accountable for behavioral effect in the FST. PMID:15936065

  14. Active ultrasonic joint integrity adjudication for real-time structural health monitoring

    NASA Astrophysics Data System (ADS)

    Clayton, Erik H.; Kennel, Matthew B.; Fasel, Timothy R.; Todd, Michael D.; Stabb, Mark C.; Arritt, Brandon J.

    2008-03-01

    The Operationally Responsive Space (ORS) strategy hinges, in part, on realizing technologies which can facilitate the rapid deployment of satellites. Presently, preflight qualification testing and vehicle integration processes are time consumptive and pose as two significant hurdles which must be overcome to effectively enhance US space asset deployment responsiveness. There is a growing demand for innovative embedded Structural Health Monitoring (SHM) technologies which can be seamlessly incorporated onto payload hardware and function in parallel with satellite construction to mitigate lengthy preflight checkout procedures. In this effort our work is focused on the development of a joint connectivity monitoring algorithm which can detect, locate, and assess preload in bolted joint assemblies. Our technology leverages inexpensive, lightweight, flexible thin-film macro-fiber composite (MFC) sensor/actuators with a novel online, data-driven signal processing algorithm. This algorithm inherently relies upon Chaotic Guided Ultrasonic Waves (CGUW) and a novel cross-prediction error classification technique. The efficacy of the monitoring algorithm is evaluated through a series of numerical simulations and experimentally in two test configurations. We conclude with a discussion surrounding further development of this approach into a commercial product as a real-time flight readiness indicator.

  15. Ankle Joint Angle and Lower Leg Musculotendinous Unit Responses to Cryotherapy.

    PubMed

    Akehi, Kazuma; Long, Blaine C; Warren, Aric J; Goad, Carla L

    2016-09-01

    Akehi, K, Long, BC, Warren, AJ, and Goad, CL. Ankle joint angle and lower leg musculotendinous unit responses to cryotherapy. J Strength Cond Res 30(9): 2482-2492, 2016-The use of cold application has been debated for its influence on joint range of motion (ROM) and stiffness. The purpose of this study was to determine whether a 30-minute ice bag application to the plantarflexor muscles or ankle influences passive ankle dorsiflexion ROM and lower leg musculotendinous stiffness (MTS). Thirty-five recreationally active college-aged individuals with no history of lower leg injury 6 months before data collection volunteered. On each testing day, we measured maximum passive ankle dorsiflexion ROM (°) and plantarflexor torque (N·m) on an isokinetic dynamometer to calculate the passive plantarflexor MTS (N·m per degree) at 4 joint angles before, during, and after a treatment. Surface electromyography amplitudes (μV), and skin surface and ambient air temperature (°C) were also measured. Subjects received an ice bag to the posterior lower leg, ankle joint, or nothing for 30 minutes in different days. Ice bag application to the lower leg and ankle did not influence passive ROM (F(12,396) = 0.67, p = 0.78). Passive torque increased after ice bag application to the lower leg (F(12,396) = 2.21, p = 0.011). Passive MTS at the initial joint angle increased after ice bag application to the lower leg (F(12,396) = 2.14, p = 0.014) but not at the other joint angles (p > 0.05). Surface electromyography amplitudes for gastrocnemius and soleus muscles increased after ice application to the lower leg (F(2,66) = 5.61, p = 0.006; F(12,396) = 3.60, p < 0.001). Ice bag application to the lower leg and ankle joint does not alter passive dorsiflexion ROM but increases passive ankle plantarflexor torque in addition to passive ankle plantarflexor MTS at the initial joint angle. PMID:26863585

  16. Torque-mixing magnetic resonance spectroscopy.

    PubMed

    Losby, J E; Fani Sani, F; Grandmont, D T; Diao, Z; Belov, M; Burgess, J A J; Compton, S R; Hiebert, W K; Vick, D; Mohammad, K; Salimi, E; Bridges, G E; Thomson, D J; Freeman, M R

    2015-11-13

    A universal, torque-mixing method for magnetic resonance spectroscopy is presented. In analogy to resonance detection by magnetic induction, the transverse component of a precessing dipole moment can be measured in sensitive broadband spectroscopy, here using a resonant mechanical torque sensor. Unlike induction, the torque amplitude allows equilibrium magnetic properties to be monitored simultaneously with the spin dynamics. Comprehensive electron spin resonance spectra of a single-crystal, mesoscopic yttrium iron garnet disk at room temperature reveal assisted switching between magnetization states and mode-dependent spin resonance interactions with nanoscale surface imperfections. The rich detail allows analysis of even complex three-dimensional spin textures. The flexibility of microelectromechanical and optomechanical devices combined with broad generality and capabilities of torque-mixing magnetic resonance spectroscopy offers great opportunities for development of integrated devices. PMID:26564851

  17. Torque equilibrium attitude control for Skylab reentry

    NASA Technical Reports Server (NTRS)

    Glaese, J. R.; Kennel, H. F.

    1979-01-01

    All the available torque equilibrium attitudes (most were useless from the standpoint of lack of electrical power) and the equilibrium seeking method are presented, as well as the actual successful application during the 3 weeks prior to Skylab reentry.

  18. Exhaust powered drive shaft torque enhancer

    SciTech Connect

    Koch, A.B.

    1986-09-30

    This patent describes a power producing combination including an internal combustion engine and a mounting frame therefor, and power transmission means including rotating drive shaft means connected to the engine. The improvement described here is a drive shaft torque enhancing device, the device comprising: a multiplicity of blades secured to the drive shaft, equally spaced therearound, each generally lying in a plane containing the axis of the drive shaft; torque enhancer feed duct means for selectively directing a stream of exhaust gases from the engine to impact against the blades to impart torque to the drive shaft; and wherein the power producing combination is used in a vehicle, the vehicle having braking means including a brake pedal; and the power producing combination further comprising torque enhancer disengagement means responsive to motion of the brake pedal.

  19. Fourth-order acoustic torque in intense sound fields

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Kanber, H.; Olli, E. E.

    1978-01-01

    The observation of a fourth-order acoustic torque in intense sound fields is reported. The torque was determined by measuring the acoustically induced angular deflection of a polished cylinder suspended by a torsion fiber. This torque was measured in a sound field of amplitude greater than that in which first-order acoustic torque has been observed.

  20. Torque and Learning and Behavior Problems in Children.

    ERIC Educational Resources Information Center

    Zendel, Ivan H.; Pihl, R. O.

    1980-01-01

    Findings indicate minimal differences, on diagnostic tests, between children who exhibited torque and those who did not. Torque is defined as the circling of any X in a clockwise direction. Torque is not associated with learning problems in school. Diagnostic utility of torque should be carefully considered. (Author)

  1. Force and torque production in static multifinger prehension: biomechanics and control. I. Biomechanics.

    PubMed

    Zatsiorsky, Vladimir M; Gregory, Robert W; Latash, Mark L

    2002-07-01

    We studied the coordinated action of fingers during static tasks involving exertion of force and torque on a handheld object. Subjects were asked to keep a handle with an attachment that allowed for independent change of the suspended load (0.5-2.0 kg) and external torque (0.375-1.5 N m) in a vertical position while applying minimal effort. Normal and shear forces were measured from the thumb; normal forces only were measured from the four fingers. EXPERIMENTAL RESULTS: (1) the thumb shear force increased during supination efforts and decreased during pronation efforts; (2) the total moment of the normal finger forces only counterbalanced approximately 50% of the external torque, hence shear forces accounted for approximately one-half of the total torque exerted on the object; (3) the total normal force increased with external torque, and the total force magnitude did not depend on the torque direction; (4) the forces of the 'peripheral' (index and little) fingers depended mainly on the torque while the forces exerted by the 'central' (middle and ring) fingers depended both on the load and torque; (5) there was a monotonic relationship between the mechanical advantage of a finger (i.e., its moment arm during torque production) and the force produced by that finger; and (6) antagonist finger moments acting opposite to the intended direction of the total moment were always observed - at low torques the antagonist moments were as high as 40-60% of the agonist moments. MODELING: A three-zone model of coordinated finger action is suggested. In the first zone of load/torque combinations, activation of antagonist fingers (i.e., fingers that generate antagonist moments) is necessary to prevent slipping. In the second zone, the activity of agonist fingers is sufficient for preventing slips. In the third zone, the performer has freedom to choose between either activating the antagonist fingers or redistributing activities amongst the agonist fingers. The findings of this

  2. Force and torque production in static multifinger prehension: biomechanics and control. I. Biomechanics

    PubMed Central

    Zatsiorsky, Vladimir M.; Gregory, Robert W.; Latash, Mark L.

    2010-01-01

    We studied the coordinated action of fingers during static tasks involving exertion of force and torque on a handheld object. Subjects were asked to keep a handle with an attachment that allowed for independent change of the suspended load (0.5–2.0 kg) and external torque (0.375–1.5 N m) in a vertical position while applying minimal effort. Normal and shear forces were measured from the thumb; normal forces only were measured from the four fingers. Experimental results (1) the thumb shear force increased during supination efforts and decreased during pronation efforts; (2) the total moment of the normal finger forces only counterbalanced approximately 50% of the external torque, hence shear forces accounted for approximately one-half of the total torque exerted on the object; (3) the total normal force increased with external torque, and the total force magnitude did not depend on the torque direction; (4) the forces of the ‘peripheral’ (index and little) fingers depended mainly on the torque while the forces exerted by the ‘central’ (middle and ring) fingers depended both on the load and torque; (5) there was a monotonic relationship between the mechanical advantage of a finger (i.e., its moment arm during torque production) and the force produced by that finger; and (6) antagonist finger moments acting opposite to the intended direction of the total moment were always observed –at low torques the antagonist moments were as high as 40–60% of the agonist moments. Modeling A three-zone model of coordinated finger action is suggested. In the first zone of load/torque combinations, activation of antagonist fingers (i.e., fingers that generate antagonist moments) is necessary to prevent slipping. In the second zone, the activity of agonist fingers is sufficient for preventing slips. In the third zone, the performer has freedom to choose between either activating the antagonist fingers or redistributing activities amongst the agonist fingers. The

  3. Large amplitude oscillation of magnetization in spin-torque oscillator stabilized by field-like torque

    SciTech Connect

    Taniguchi, Tomohiro Kubota, Hitoshi; Imamura, Hiroshi; Tsunegi, Sumito

    2015-05-07

    Oscillation frequency of spin torque oscillator with a perpendicularly magnetized free layer and an in-plane magnetized pinned layer is theoretically investigated by taking into account the field-like torque. It is shown that the field-like torque plays an important role in finding the balance between the energy supplied by the spin torque and the dissipation due to the damping, which results in a steady precession. The validity of the developed theory is confirmed by performing numerical simulations based on the Landau-Lifshitz-Gilbert equation.

  4. Large amplitude oscillation of magnetization in spin-torque oscillator stabilized by field-like torque

    NASA Astrophysics Data System (ADS)

    Taniguchi, Tomohiro; Tsunegi, Sumito; Kubota, Hitoshi; Imamura, Hiroshi

    2015-05-01

    Oscillation frequency of spin torque oscillator with a perpendicularly magnetized free layer and an in-plane magnetized pinned layer is theoretically investigated by taking into account the field-like torque. It is shown that the field-like torque plays an important role in finding the balance between the energy supplied by the spin torque and the dissipation due to the damping, which results in a steady precession. The validity of the developed theory is confirmed by performing numerical simulations based on the Landau-Lifshitz-Gilbert equation.

  5. Proprioceptive deficit in individuals with unilateral tearing of the anterior cruciate ligament after active evaluation of the sense of joint position☆☆☆

    PubMed Central

    Cossich, Victor; Mallrich, Frédéric; Titonelli, Victor; de Sousa, Eduardo Branco; Velasques, Bruna; Salles, José Inácio

    2014-01-01

    Objective To ascertain whether the proprioceptive deficit in the sense of joint position continues to be present when patients with a limb presenting a deficient anterior cruciate ligament (ACL) are assessed by testing their active reproduction of joint position, in comparison with the contralateral limb. Methods Twenty patients with unilateral ACL tearing participated in the study. Their active reproduction of joint position in the limb with the deficient ACL and in the healthy contralateral limb was tested. Meta-positions of 20% and 50% of the maximum joint range of motion were used. Proprioceptive performance was determined through the values of the absolute error, variable error and constant error. Results Significant differences in absolute error were found at both of the positions evaluated, and in constant error at 50% of the maximum joint range of motion. Conclusion When evaluated in terms of absolute error, the proprioceptive deficit continues to be present even when an active evaluation of the sense of joint position is made. Consequently, this sense involves activity of both intramuscular and tendon receptors. PMID:26229869

  6. Torque-mixing Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Losby, Joseph; Fani Sani, Fatemeh; Grandmont, Dylan; Diao, Zhu; Belov, Miro; Burgess, Jacob; Compton, Shawn; Hiebert, Wayne; Vick, Doug; Mohammad, Kaveh; Salimi, Elham; Bridges, Gregory; Thomson, Douglas; Freeman, Mark

    A universal, mechanical torque method for magnetic resonance spectroscopy is presented. In analogy to resonance detection by induction, a signal proportional to the transverse component of a precessing dipole moment can be measured as a pure mechanical torque in broadband, frequency-swept spectroscopy. Comprehensive electron spin resonance of a single-crystal, mesoscopic yttrium iron garnet disk at room temperature are presented to demonstrate the method. The rich detail allows analysis of even complex 3D spin textures.

  7. Mandibular lip bumper for molar torque control.

    PubMed

    Celentano, Giuseppe; Longobardi, Annalisa; Cannavale, Rosangela; Perillo, Letizia

    2011-01-01

    Treatment effects of lip bumpers alone include flaring of the mandibular incisors, distalization and uprighting of the mandibular first molars, and buccal expansion of the canines, premolars, and molar. Lip forces are transmitted through this appliance onto the molars. Moreover the lip bumper is able to derotate, expand or constrict, upright and reinforce the anchorage whereas torque control is lacking. Aim of this paper is the presentation of a new type of lip bumper that allows the molar torque control. PMID:21515237

  8. Fast joint detection-estimation of evoked brain activity in event-related FMRI using a variational approach

    PubMed Central

    Chaari, Lotfi; Vincent, Thomas; Forbes, Florence; Dojat, Michel; Ciuciu, Philippe

    2013-01-01

    In standard within-subject analyses of event-related fMRI data, two steps are usually performed separately: detection of brain activity and estimation of the hemodynamic response. Because these two steps are inherently linked, we adopt the so-called region-based Joint Detection-Estimation (JDE) framework that addresses this joint issue using a multivariate inference for detection and estimation. JDE is built by making use of a regional bilinear generative model of the BOLD response and constraining the parameter estimation by physiological priors using temporal and spatial information in a Markovian model. In contrast to previous works that use Markov Chain Monte Carlo (MCMC) techniques to sample the resulting intractable posterior distribution, we recast the JDE into a missing data framework and derive a Variational Expectation-Maximization (VEM) algorithm for its inference. A variational approximation is used to approximate the Markovian model in the unsupervised spatially adaptive JDE inference, which allows automatic fine-tuning of spatial regularization parameters. It provides a new algorithm that exhibits interesting properties in terms of estimation error and computational cost compared to the previously used MCMC-based approach. Experiments on artificial and real data show that VEM-JDE is robust to model mis-specification and provides computational gain while maintaining good performance in terms of activation detection and hemodynamic shape recovery. PMID:23096056

  9. A reactive torque control law for gyroscopically controlled space vehicles

    NASA Technical Reports Server (NTRS)

    Farmer, J. E.

    1973-01-01

    A method of control is developed based on the reactive torques as seen by the individual CMG gimbals. The application of a torque to the gimbal of a CMG rotates the momentum vector and applies a torque to the spacecraft according to well-known laws. The response (rotation) of the vehicle produces a reverse or reaction torque opposing the torque producing the gimbal movement. The reactive torque and the pseudoinverse control schemes are contrasted in order to point out the simplicity of the first method. Simulation was performed only to the extent necessary to prove that reactive torque stabilization and control is feasible.

  10. Modulation of the Relationship Between External Knee Adduction Moments and Medial Joint Contact Forces Across Subjects and Activities

    PubMed Central

    Trepczynski, Adam; Kutzner, Ines; Bergmann, Georg; Taylor, William R; Heller, Markus O

    2014-01-01

    Objective The external knee adduction moment (EAM) is often considered a surrogate measure of the distribution of loads across the tibiofemoral joint during walking. This study was undertaken to quantify the relationship between the EAM and directly measured medial tibiofemoral contact forces (Fmed) in a sample of subjects across a spectrum of activities. Methods The EAM for 9 patients who underwent total knee replacement was calculated using inverse dynamics analysis, while telemetric implants provided Fmed for multiple repetitions of 10 activities, including walking, stair negotiation, sit-to-stand activities, and squatting. The effects of the factors “subject” and “activity” on the relationships between Fmed and EAM were quantified using mixed-effects regression analyses in terms of the root mean square error (RMSE) and the slope of the regression. Results Across subjects and activities a good correlation between peak EAM and Fmed values was observed, with an overall R2 value of 0.88. However, the slope of the linear regressions varied between subjects by up to a factor of 2. At peak EAM and Fmed, the RMSE of the regression across all subjects was 35% body weight (%BW), while the maximum error was 127 %BW. Conclusion The relationship between EAM and Fmed is generally good but varies considerably across subjects and activities. These findings emphasize the limitation of relying solely on the EAM to infer medial joint loading when excessive directed cocontraction of muscles exists and call for further investigations into the soft tissue–related mechanisms that modulate the internal forces at the knee. PMID:24470261

  11. Total joint replacement: A multiple risk factor analysis of physical activity level 1–2 years postoperatively

    PubMed Central

    Torres, Andy; Love, Rebecca M; Barber, Thomas C; Sheth, Dhiren S; Inacio, Maria C S

    2016-01-01

    Background and purpose — The effect of total joint arthroplasty (TJA) on physical activity is not fully understood. We investigated the change in physical activity after TJA and patient factors associated with change. Patients and methods — Using a total joint replacement registry, primary total hip arthroplasty (THA) patients (n = 5,678) and knee arthroplasty (TKA) patients (n = 11,084) between January 1, 2010 and December 31, 2012 were identified. Median age at THA was 68 and median age at TKA was 67. Change in self-reported physical activity (minutes per week) from before TJA (within 1 year of surgery) to after TJA (1–2 years) was the outcome of interest. Patient demographics and comorbidities were evaluated as risk factors. Multiple linear regression was used. Results — Median physical activity before surgery was 50 min/week (IQR: 0–140) for THA patients and 58 (IQR: 3–143) for TKA patients. Median physical activity after surgery was 150 min/week (IQR: 60–280) for both THA patients and TKA patients. Following TJA, 50% of patients met CDC/WHO physical activity guideline criteria. Higher body mass index was associated with lower change in physical activity (THA: −7.1 min/week; TKA: −5.9 min/week). Females had lower change than males (THA: −11 min/week; TKA: −9.1 min/week). In TKA patients, renal failure was associated with lower change (−17 min/week), as were neurological disorders (−30 min/week). Interpretation — Self-reported minutes of physical activity increased from before to after TJA, but 50% of TJA patients did not meet recommended physical activity guideline criteria. Higher body mass index, female sex, and specific comorbidities were found to be associated with low change in physical activity. Patient education on the benefits of physical activity should concentrate on these subgroups of patients. PMID:27299567

  12. Extraneous torque and compensation control on the electric load simulator

    NASA Astrophysics Data System (ADS)

    Jiao, Zongxia; Li, Chenggong; Ren, Zhiting

    2003-09-01

    In this paper a novel motor-drive load simulator based on compensation control strategy is proposed and designed. Through analyzing the torque control system consisting of DC torque motor, PWM module and torque sensor, it is shown that performance of the motor-drive load simulator is possible to be as good as that of the electro-hydraulic load simulator in the range of small torque. In the course of loading, the rotation of the actuator would cause a strong disturbance torque through the motor back-EMF, which produces extraneous torque similar as in electro-hydraulic load simulator. This paper analyzes the cause of extraneous torque inside the torque motor in detail and presents an appropriate compensation control with which the extraneous torque can be compensated and the good performance of the torque control system can be obtained. The results of simulation indicate that the compensation is very effective and the track performance is according with the request.

  13. Knudsen torque on heated micro beams

    SciTech Connect

    Li, Qi; Liang, Tengfei; Ye, Wenjing

    2014-12-09

    Thermally induced mechanical loading has been shown to have significant effects on micro/nano objects immersed in a gas with a non-uniform temperature field. While the majority of existing studies and related applications focus on forces, we investigate the torque, and thus the rotational motion, produced by such a mechanism. Using the asymptotic analysis in the near continuum regime, the Knudsen torque acting on an asymmetrically located uniformly heated microbeam in a cold enclosure is investigated. The existence of a non-zero net torque is demonstrated. In addition, it has been found that by manipulating the system configuration, the rotational direction of the torque can be changed. Two types of rotational motion of the microbeam have been identified: the pendulum motion of a rectangular beam, and the unidirectional rotation of a cylindrical beam. A rotational frequency of 4 rpm can be achieved for the cylindrical beam with a diameter of 3μm at Kn = 0.005. Illustrated by the simulations using the direct simulation of Monte Carlo, the Knudsen torque can be much increased in the transition regime, demonstrating the potential of Knudsen torque serving as a rotation engine for micro/nano objects.

  14. Handle displacement and operator responses to pneumatic nutrunner torque buildup.

    PubMed

    Lin, Jia-Hua; McGorry, Raymond W; Dempsey, Patrick G; Chang, Chien-Chi

    2006-05-01

    The objective of this study is to investigate the workstation and tool effects on the responses of the powered hand tool operator reacting against the impulsive reaction forces that may be associated with upper extremity musculoskeletal disorders. The study demonstrated a means of direct measurement of force at the interface between the tool and the operator. Fifteen experienced male operators performed three independent work configurations: pistol grip and right angle tools used on the horizontal surface and pistol grip tools used on the vertical surface, in the laboratory. A full factorial experiment consisting of 36 conditions was designed to examine the effects of working height, distance, tool, and fastener joint hardness on handle displacement and grip forces. The results indicate that operator responses were affected by different factors depending on the work configuration. When pistol grip tools were used on the vertical surface, the mean handle displacement decreased from 9.9 degrees to 7.3 degrees as the working height increased from 30 cm below shoulder to 30 cm above shoulder. When right angle tools were used, the greatest handle displacement (51.1mm) and grip force (84.7% MVC) during torque reactions were measured at 30 cm below elbow and 40% forward reach away from the operator. This study provides quantitative information that can be used for workstation design and tool selection to reduce the torque reaction experienced by powered nutrunner operators. PMID:16202971

  15. Continuous torque system with control of the reaction unit.

    PubMed

    Gandini, Luiz Gonzaga; Gandini, Márcia Regina Elisa Aparecida Schiavon; Amaral, Roberta Maria de Paula

    2010-03-01

    This article describes an orthodontic system used to obtain active continuous torque with movement control of both active and reactive units; the system relies on principles of the segmented technique. A cantilever system with .017 x .025-in beta-titanium alloy wire was designed to provide the desirable moment on the active unit. A transpalatal bar or a lingual arch increases the anchorage and neutralizes the side effects on the reactive unit. This technique is an efficient approach for major corrections of buccolingual inclinations of certain teeth. PMID:20197179

  16. Joint United States and People`s Republic of China clean coal activities. Annual report, April 1994--December 1995

    SciTech Connect

    1996-06-01

    The United States Department of Energy (U.S. DOE) and the Ministry of Coal Industry of the People`s Republic of China (China) signed a protocol in the field of fossil energy research and development in April 1985. An annex to this agreement, Annex IX, was signed in April 1994 for cooperation between the U.S. DOE and China`s State Science and Technology Commission (SSTC) in the area of clean coal utilization. Article III of Annex IX requires the United States and China jointly to prepare an annual report i describing the work performed and results achieved. This report, in compliance with Article III, is a description of the activities conducted under Annex IX during the period from April 1994 through December 1995. The report also contains the plans for future activities for the next 12 months, or through December 1996.

  17. Comparison of joint angles and electromyographic activity of the lower extremities during standing with wearing standard and revised high-heeled shoes: A pilot study.

    PubMed

    Bae, Young-Hyeon; Ko, Mansoo; Lee, Suk Min

    2016-04-29

    Revised high-heeled shoes (HHSs) were designed to improve the shortcomings of standard HHSs. This study was conducted to compare revised and standard HHSs with regard to joint angles and electromyographic (EMG) activity of the lower extremities during standing. The participants were five healthy young women. Data regarding joint angles and EMG activity of the lower extremities were obtained under three conditions: barefoot, when wearing revised HHSs, and when wearing standard HHSs. Lower extremity joint angles in the three dimensional plane were confirmed using a VICON motion capture system. EMG activity of the lower extremities was measured using active bipolar surface EMG. Kruskal-Wallis one-way analysis of variance by rank applied to analyze differences during three standing conditions. Compared with the barefoot condition, the standard HHSs condition was more different than the revised HHSs condition with regard to lower extremity joint angles during standing. EMG activity of the lower extremities was different for the revised HHSs condition, but the differences among the three conditions were not significant. Wearing revised HHSs may positively impact joint angles and EMG activity of the lower extremities by improving body alignment while standing. PMID:27163313

  18. Dynamic activation of bone morphogenetic protein signaling in collagen-induced arthritis supports their role in joint homeostasis and disease

    PubMed Central

    Daans, Melina; Lories, Rik JU; Luyten, Frank P

    2008-01-01

    Introduction Rheumatoid arthritis is a chronic systemic autoimmune disease affecting peripheral joints and leading to loss of joint function. The severity and outcome of disease are dependent on the balance between inflammatory/destructive and homeostatic or repair pathways. Increasing evidence suggests a role for bone morphogenetic protein (BMP) signaling in joint homeostasis and disease. Methods Activation of BMP signaling in collagen-induced arthritis as a model of rheumatoid arthritis was studied by immunohistochemistry and Western blot for phosphorylated SMAD1/5 at different time points. Expression of different BMP ligands and noggin, a BMP antagonist, was determined on synovium and cartilage extracts of arthritic knees, at different time points, with quantitative polymerase chain reaction. At the protein level, BMP2 and BMP7 were studied with immunohistochemistry. Finally, the effect of anti-tumor necrosis factor-alpha (TNFα) treatment on the expression of BMP2, BMP7, and growth and differentiation factor-5 (GDF5) in synovium and cartilage of arthritic knees was investigated. Results A time-dependent activation of the BMP signaling pathway in collagen-induced arthritis was demonstrated with a dynamic and characteristic expression pattern of different BMP subfamily members in synovium and cartilage of arthritic knees. As severity increases, the activation of BMP signaling becomes more prominent in the invasive pannus tissue. BMP2 is present in cartilage and the hyperplastic lining layer. BMP7 is found in the sublining zone and inflammatory infiltrate. Treatment with etanercept slowed down progression of disease, but no change in expression of GDF5, BMP2, and BMP7 in synovium was found; in the cartilage, however, blocking of TNFα increased the expression of BMP7. Conclusions BMP signaling is dynamically activated in collagen-induced arthritis and is partly TNFα-independent. TNFα blocking increased the expression of BMP7 in the articular cartilage, possibly

  19. The Challenge of Limiting Greenhouse Gas Emissions Through Activities implemented Jointly in Developing Countries: A Brazilian Perspective

    SciTech Connect

    La Rovere, E.L.

    1998-11-01

    This paper addresses, from the Brazilian perspective, the main problems with Joint Implementation/Activities Implemented Jointly (JI/AIJ) between industrialized (Annex I) and developing (non-Annex I) countries, as defined by the United Nations Framework Convention on Climate Change (UNFCCC). Four possible GHG emissions abatement measures are presented for Brazil: forest protection, reforestation projects for carbon sequestration or charcoal manufacturing, use of ethanol produced from sugar cane as a car fuel, and electrical energy conservation through an increase in end-use efficiencies. These four case studies form the basis of a discussion regarding the validity of developing countries' concerns about JI/AIJ. Recommendations are offered for overcoming the present shortcomings of JI/AIJ in developing countries. The primary conclusion is that Annex I countries' funding of JI/AIJ projects in developing countries in return for GHG emissions credits is not the best means to implement the UNFCCC. However, JI/AIJ projects can be a productive means of preventing global climate change if combined with other measures, including GHG emissions reduction targets for all countries involved in JI/AIJ projects and limits on the percentage of industrialized countries' emissions reductions that can be met through projects in developing countries.

  20. Effects of hip and head position on ankle range of motion, ankle passive torque, and passive gastrocnemius tension.

    PubMed

    Andrade, R J; Lacourpaille, L; Freitas, S R; McNair, P J; Nordez, A

    2016-01-01

    Ankle joint range of motion (ROM) is notably influenced by the position of the hip joint. However, this result remains unexplained. Thus, the aim of this study was to test if the ankle passive torque and gastrocnemius muscle tension are affected by the hip and the head positions. The torque and the muscle shear elastic modulus (measured by elastography to estimate muscle tension) were collected in nine participants during passive ankle dorsiflexions performed in four conditions (by combining hip flexion at 90 or 150°, and head flexed or neutral). Ankle maximum dorsiflexion angle significantly decreased by flexing the hip from 150 to 90° (P < 0.001; mean difference 17.7 ± 2.5°), but no effect of the head position was observed (P > 0.05). Maximal passive torque and shear elastic modulus were higher with the hip flexed at 90° (P < 0.001). During submaximal ROM, no effects of the head and hip positioning (P > 0.05) were found for both torque and shear elastic modulus at a given common ankle angle among conditions. Shifts in maximal ankle angle due to hip angle manipulation are not related neither to changes in passive torque nor tension of the gastrocnemius. Further studies should be addressed to better understand the functional role of peripheral nerves and fasciae in the ankle ROM limits. PMID:25676048

  1. Self-oscillation in spin torque oscillator stabilized by field-like torque

    SciTech Connect

    Taniguchi, Tomohiro; Tsunegi, Sumito; Kubota, Hitoshi; Imamura, Hiroshi

    2014-04-14

    The effect of the field-like torque on the self-oscillation of the magnetization in spin torque oscillator with a perpendicularly magnetized free layer was studied theoretically. A stable self-oscillation at zero field is excited for negative β while the magnetization dynamics stops for β = 0 or β > 0, where β is the ratio between the spin torque and the field-like torque. The reason why only the negative β induces the self-oscillation was explained from the view point of the energy balance between the spin torque and the damping. The oscillation power and frequency for various β were also studied by numerical simulation.

  2. Feedback-based mitigation of torque harmonics in interior permanent magnet synchronous machines

    NASA Astrophysics Data System (ADS)

    Vaks, Nir

    Harmonics in the electromagnetic torque are a source of concern in permanent magnet synchronous machine (PMSM) drives. The harmonics are created by non-idealities in the electromagnetic fields produced by the magnets and the stator excitation. They lead to vibration that can cause premature wear of the drivetrain components as well as acoustic noise that may be bothersome to users. In this research, current- and voltage-based control schemes have been developed to mitigate the harmonics in a class of PMSMs in which the magnets are placed interior to the rotor iron. Interior permanent magnet synchronous machines (IPMSMs) have recently gained popularity for applications including hybrid electric vehicles and robot joint control. In the current-based control, a low-cost piezoelectric sensor is used to measure torque harmonics. A conjugate gradient algorithm is then applied to search for harmonics in the stator current that produce a commanded average torque while eliminating the measured torque harmonics. The algorithm is based upon analytical closed-form expressions for the average and harmonic components of torque that have been derived for IPMSMS with arbitrary back-emf waveforms. In the voltage-based control, a time-domain model of the machine is used to map the outputs of the conjugate gradient algorithm to commanded stator voltages. Since both utilize feedback, the controls are insensitive to changes in machine parameters that result from magnetic saturation, temperature, or parameter drift. In addition, the user has flexibility to select the harmonic(s) of torque to be eliminated.

  3. Muscle shear elastic modulus is linearly related to muscle torque over the entire range of isometric contraction intensity.

    PubMed

    Ateş, Filiz; Hug, François; Bouillard, Killian; Jubeau, Marc; Frappart, Thomas; Couade, Mathieu; Bercoff, Jeremy; Nordez, Antoine

    2015-08-01

    Muscle shear elastic modulus is linearly related to muscle torque during low-level contractions (<60% of Maximal Voluntary Contraction, MVC). This measurement can therefore be used to estimate changes in individual muscle force. However, it is not known if this relationship remains valid for higher intensities. The aim of this study was to determine: (i) the relationship between muscle shear elastic modulus and muscle torque over the entire range of isometric contraction and (ii) the influence of the size of the region of interest (ROI) used to average the shear modulus value. Ten healthy males performed two incremental isometric little finger abductions. The joint torque produced by Abductor Digiti Minimi was considered as an index of muscle torque and elastic modulus. A high coefficient of determination (R(2)) (range: 0.86-0.98) indicated that the relationship between elastic modulus and torque can be accurately modeled by a linear regression over the entire range (0% to 100% of MVC). The changes in shear elastic modulus as a function of torque were highly repeatable. Lower R(2) values (0.89±0.13 for 1/16 of ROI) and significantly increased absolute errors were observed when the shear elastic modulus was averaged over smaller ROI, half, 1/4 and 1/16 of the full ROI) than the full ROI (mean size: 1.18±0.24cm(2)). It suggests that the ROI should be as large as possible for accurate measurement of muscle shear modulus. PMID:25956546

  4. Force, Torque and Stiffness: Interactions in Perceptual Discrimination

    PubMed Central

    Wu, Bing; Klatzky, Roberta L.; Hollis, Ralph L.

    2011-01-01

    Three experiments investigated whether force and torque cues interact in haptic discrimination of force, torque and stiffness, and if so, how. The statistical relation between force and torque was manipulated across four experimental conditions: Either one type of cue varied while the other was constant, or both varied so as to be positively correlated, negatively correlated, or uncorrelated. Experiment 1 showed that the subjects’ ability to discriminate force was improved by positively correlated torque but impaired with uncorrelated torque, as compared to the constant torque condition. Corresponding effects were found in Experiment 2 for the influence of force on torque discrimination. These findings indicate that force and torque are integrated in perception, rather than being processed as separate dimensions. A further experiment demonstrated facilitation of stiffness discrimination by correlated force and torque, whether the correlation was positive or negative. The findings suggest new means of augmenting haptic feedback to facilitate perception of the properties of soft objects. PMID:21359137

  5. Wear Testing of Moderate Activities of Daily Living Using In Vivo Measured Knee Joint Loading

    PubMed Central

    Reinders, Jörn; Sonntag, Robert; Vot, Leo; Gibney, Christian; Nowack, Moritz; Kretzer, Jan Philippe

    2015-01-01

    Resumption of daily living activities is a basic expectation for patients provided with total knee replacements. However, there is a lack of knowledge regarding the impact of different activities on the wear performance. In this study the wear performance under application of different daily activities has been analyzed. In vivo load data for walking, walking downstairs/upstairs, sitting down/standing up, and cycling (50 W & 120 W) has been standardized for wear testing. Wear testing of each activity was carried out on a knee wear simulator. Additionally, ISO walking was tested for reasons of comparison. Wear was assessed gravimetrically and wear particles were analyzed. In vivo walking produced the highest overall wear rates, which were determined to be three times higher than ISO walking. Moderate wear rates were determined for walking upstairs and downstairs. Low wear rates were determined for standing up/sitting down and cycling at power levels of 50 W and 120 W. The largest wear particles were observed for cycling. Walking based on in vivo data has been shown to be the most wear-relevant activity. Highly demanding activities (stair climbing) produced considerably less wear. Taking into account the expected number of loads, low-impact activities like cycling may have a greater impact on articular wear than highly demanding activities. PMID:25811996

  6. Feasibility study for convertible engine torque converter

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The feasibility study has shown that a dump/fill type torque converter has excellent potential for the convertible fan/shaft engine. The torque converter space requirement permits internal housing within the normal flow path of a turbofan engine at acceptable engine weight. The unit permits operating the engine in the turboshaft mode by decoupling the fan. To convert to turbofan mode, the torque converter overdrive capability bring the fan speed up to the power turbine speed to permit engagement of a mechanical lockup device when the shaft speed are synchronized. The conversion to turbofan mode can be made without drop of power turbine speed in less than 10 sec. Total thrust delivered to the aircraft by the proprotor, fan, and engine during tansient can be controlled to prevent loss of air speed or altitude. Heat rejection to the oil is low, and additional oil cooling capacity is not required. The turbofan engine aerodynamic design is basically uncompromised by convertibility and allows proper fan design for quiet and efficient cruise operation. Although the results of the feasibility study are exceedingly encouraging, it must be noted that they are based on extrapolation of limited existing data on torque converters. A component test program with three trial torque converter designs and concurrent computer modeling for fluid flow, stress, and dynamics, updated with test results from each unit, is recommended.

  7. Torque shudder protection device and method

    DOEpatents

    King, Robert D.; De Doncker, Rik W. A. A.; Szczesny, Paul M.

    1997-01-01

    A torque shudder protection device for an induction machine includes a flux command generator for supplying a steady state flux command and a torque shudder detector for supplying a status including a negative status to indicate a lack of torque shudder and a positive status to indicate a presence of torque shudder. A flux adapter uses the steady state flux command and the status to supply a present flux command identical to the steady state flux command for a negative status and different from the steady state flux command for a positive status. A limiter can receive the present flux command, prevent the present flux command from exceeding a predetermined maximum flux command magnitude, and supply the present flux command to a field oriented controller. After determining a critical electrical excitation frequency at which a torque shudder occurs for the induction machine, a flux adjuster can monitor the electrical excitation frequency of the induction machine and adjust a flux command to prevent the monitored electrical excitation frequency from reaching the critical electrical excitation frequency.

  8. Torque shudder protection device and method

    DOEpatents

    King, R.D.; Doncker, R.W.A.A. De.; Szczesny, P.M.

    1997-03-11

    A torque shudder protection device for an induction machine includes a flux command generator for supplying a steady state flux command and a torque shudder detector for supplying a status including a negative status to indicate a lack of torque shudder and a positive status to indicate a presence of torque shudder. A flux adapter uses the steady state flux command and the status to supply a present flux command identical to the steady state flux command for a negative status and different from the steady state flux command for a positive status. A limiter can receive the present flux command, prevent the present flux command from exceeding a predetermined maximum flux command magnitude, and supply the present flux command to a field oriented controller. After determining a critical electrical excitation frequency at which a torque shudder occurs for the induction machine, a flux adjuster can monitor the electrical excitation frequency of the induction machine and adjust a flux command to prevent the monitored electrical excitation frequency from reaching the critical electrical excitation frequency. 5 figs.

  9. Torque equilibrium attitude control for Skylab reentry

    NASA Technical Reports Server (NTRS)

    Glaese, J. R.; Kennel, H. F.

    1980-01-01

    The method of torque equilibrium attitude control used to control the reentry of Skylab to an altitude below 150 km without the use of thruster fuel once the attitude was established is discussed. The Skylab attitude and pointing control system, which included rate gyros, sun sensors, star tracker, the Apollo telescope mount digital computer, control moment gyros and cold-gas attitude thrusters, is presented. The 12 torque equilibrium attitudes found at which aerodynamic, gravity gradient and gyroscopic torques would balance are indicated, and the three of those at which the solar power supply would be adequate for attitude control are illustrated. The equilibrium seeking method employed is then examined, and the operation and performance of the torque equilibrium attitude control system during the three weeks prior to Skylab reentry are discussed. It is concluded that the torque equilibrium attitude control method developed for Skylab was successful in performing its assigned mission, and will be valuable for the design of future, low-altitude spacecraft or tethered vehicles.

  10. Active vibration control of Flexible Joint Manipulator using Input Shaping and Adaptive Parameter Auto Disturbance Rejection Controller

    NASA Astrophysics Data System (ADS)

    Li, W. P.; Luo, B.; Huang, H.

    2016-02-01

    This paper presents a vibration control strategy for a two-link Flexible Joint Manipulator (FJM) with a Hexapod Active Manipulator (HAM). A dynamic model of the multi-body, rigid-flexible system composed of an FJM, a HAM and a spacecraft was built. A hybrid controller was proposed by combining the Input Shaping (IS) technique with an Adaptive-Parameter Auto Disturbance Rejection Controller (APADRC). The controller was used to suppress the vibration caused by external disturbances and input motions. Parameters of the APADRC were adaptively adjusted to ensure the characteristic of the closed loop system to be a given reference system, even if the configuration of the manipulator significantly changes during motion. Because precise parameters of the flexible manipulator are not required in the IS system, the operation of the controller was sufficiently robust to accommodate uncertainties in system parameters. Simulations results verified the effectiveness of the HAM scheme and controller in the vibration suppression of FJM during operation.

  11. Test-retest reliability of an active range of motion test for the shoulder and hip joints by unskilled examiners using a manual goniometer

    PubMed Central

    Kim, Seong-Gil; Kim, Eun-Kyung

    2016-01-01

    [Purpose] The purpose of this study was to analyze test-retest reliability of an active range of motion test using a manual goniometer by unskilled examiners. [Subjects and Methods] Active range of motion was measured in 30 students attending U university (4 males, 26 females). Range of motion during flexion and extension of the shoulder and hip joints were measured using a manual goniometer. [Results] Flexion and extension of the shoulder joint (ICC=0.906 and ICC=0.808) and (ICC=0.946 and ICC=0. 955) of the hip joint showed excellent reliabilities. [Conclusion] The active range of motion test using a manual goniometer showed very high test-retest reliability in unskilled examiners. When examiners are aware of the method of the test, an objective assessment can be conducted. PMID:27134347

  12. Evaluation of Anatomical and Functional Hip Joint Center Methods: The Effects of Activity Type, Gender, and Proximal Reference Segment.

    PubMed

    McGibbon, C A; Fowler, J; Chase, S; Steeves, K; Landry, J; Mohamed, A

    2016-01-01

    Accurate hip joint center (HJC) location is critical when studying hip joint biomechanics. The HJC is often determined from anatomical methods, but functional methods are becoming increasingly popular. Several studies have examined these methods using simulations and in vivo gait data, but none has studied high-range of motion activities, such a chair rise, nor has HJC prediction been compared between males and females. Furthermore, anterior superior iliac spine (ASIS) marker visibility during chair rise can be problematic, requiring a sacral cluster as an alternative proximal segment; but functional HJC has not been explored using this approach. For this study, the quality of HJC measurement was based on the joint gap error (JGE), which is the difference in global HJC between proximal and distal reference segments. The aims of the present study were to: (1) determine if JGE varies between pelvic and sacral referenced HJC for functional and anatomical methods, (2) investigate which functional calibration motion results in the lowest JGE and if the JGE varies depending on movement type (gait versus chair rise) and gender, and (3) assess whether the functional HJC calibration results in lower JGE than commonly used anatomical approaches and if it varies with movement type and gender. Data were collected on 39 healthy adults (19 males and 20 females) aged 14-50 yr old. Participants performed four hip "calibration" tests (arc, cross, star, and star-arc), as well as gait and chair rise (activities of daily living (ADL)). Two common anatomical methods were used to estimate HJC and were compared to HJC computed using a published functional method with the calibration motions above, when using pelvis or sacral cluster as the proximal reference. For ADL trials, functional methods resulted in lower JGE (12-19 mm) compared to anatomical methods (13-34 mm). It was also found that women had significantly higher JGE compared to men and JGE was significantly higher for

  13. The Effects of NMDA Antagonists on Neuronal Activity in Cat Spinal Cord Evoked by Acute Inflammation in the Knee Joint.

    PubMed

    Schaible, Hans-Georg; Grubb, Blair D.; Neugebauer, Volker; Oppmann, Maria

    1991-01-01

    In alpha-chloralose-anaesthetized, spinalized cats we examined the effects of NMDA antagonists on the discharges of 71 spinal neurons which had afferent input from the knee joint. These neurons were rendered hyperexcitable by acute arthritis in the knee induced by kaolin and carrageenan. They were located in the deep dorsal and ventral horn and some of them had ascending axons. The N-methyl-d-aspartate (NMDA) antagonists ketamine and d-2-amino-5-phosphonovalerate (AP5), were administered ionophoretically, and ketamine was also administered intravenously. In some of the experiments the antagonists were tested against the agonists NMDA and quisqualate. The effects of the NMDA antagonists consisted of a significant reduction in the resting activity of neurons and/or the responses of the same neurons to mechanical stimulation of the inflamed knee. Intravenous ketamine was most effective in suppressing the resting and mechanically evoked activity in 25 of 26 neurons tested. Ionophoretically applied ketamine had a suppressive effect in 11 of 21 neurons, and AP5 decreased activity in 17 of 24 cells. The reduction in the resting and/or the mechanically evoked discharges was achieved with doses of the antagonists which suppressed the responses to NMDA but not those to quisqualate. These results suggest that NMDA receptors are involved in the enhanced responses and basal activity of spinal neurons induced by inflammation in the periphery. PMID:12106256

  14. Activation of α2A-adrenergic signal transduction in chondrocytes promotes degenerative remodelling of temporomandibular joint.

    PubMed

    Jiao, Kai; Zeng, Guang; Niu, Li-Na; Yang, Hong-Xu; Ren, Gao-Tong; Xu, Xin-Yue; Li, Fei-Fei; Tay, Franklin R; Wang, Mei-Qing

    2016-01-01

    This study tested whether activation of adrenoreceptors in chondrocytes has roles in degenerative remodelling of temporomandibular joint (TMJ) and to determine associated mechanisms. Unilateral anterior crossbite (UAC) was established to induce TMJ degeneration in rats. Saline vehicle, α2- and β-adrenoreceptor antagonists or agonists were injected locally into the TMJ area of UAC rats. Cartilage degeneration, subchondral bone microarchitecture and the expression of adrenoreceptors, aggrecans, matrix metalloproteinases (MMPs) and RANKL by chondrocytes were evaluated. Chondrocytes were stimulated by norepinephrine to investigate signal transduction of adrenoreceptors. Increased α2A-adrenoreceptor expression was observed in condylar cartilage of UAC rats, together with cartilage degeneration and subchondral bone loss. Norepinephrine depresses aggrecans expression but stimulates MMP-3, MMP-13 and RANKL production by chondrocytes through ERK1/2 and PKA pathway; these effects were abolished by an α2A-adrenoreceptor antagonist. Furthermore, inhibition of α2A-adrenoreceptor attenuated degenerative remodelling in the condylar cartilage and subchondral bone, as revealed by increased cartilage thickness, proteoglycans and aggrecan expression, and decreased MMP-3, MMP-13 and RANKL expressions in cartilage, increased BMD, BV/TV, and decreased Tb.Sp in subchondral bone. Conversely, activation of α2A-adrenoreceptor intensified aforementioned degenerative changes in UAC rats. It is concluded that activation of α2A-adrenergic signal in chondrocytes promotes TMJ degenerative remodelling by chondrocyte-mediated pro-catabolic activities. PMID:27452863

  15. Activation of α2A-adrenergic signal transduction in chondrocytes promotes degenerative remodelling of temporomandibular joint

    PubMed Central

    Jiao, Kai; Zeng, Guang; Niu, Li-Na; Yang, Hong-xu; Ren, Gao-tong; Xu, Xin-yue; Li, Fei-fei; Tay, Franklin R.; Wang, Mei-qing

    2016-01-01

    This study tested whether activation of adrenoreceptors in chondrocytes has roles in degenerative remodelling of temporomandibular joint (TMJ) and to determine associated mechanisms. Unilateral anterior crossbite (UAC) was established to induce TMJ degeneration in rats. Saline vehicle, α2- and β-adrenoreceptor antagonists or agonists were injected locally into the TMJ area of UAC rats. Cartilage degeneration, subchondral bone microarchitecture and the expression of adrenoreceptors, aggrecans, matrix metalloproteinases (MMPs) and RANKL by chondrocytes were evaluated. Chondrocytes were stimulated by norepinephrine to investigate signal transduction of adrenoreceptors. Increased α2A-adrenoreceptor expression was observed in condylar cartilage of UAC rats, together with cartilage degeneration and subchondral bone loss. Norepinephrine depresses aggrecans expression but stimulates MMP-3, MMP-13 and RANKL production by chondrocytes through ERK1/2 and PKA pathway; these effects were abolished by an α2A-adrenoreceptor antagonist. Furthermore, inhibition of α2A-adrenoreceptor attenuated degenerative remodelling in the condylar cartilage and subchondral bone, as revealed by increased cartilage thickness, proteoglycans and aggrecan expression, and decreased MMP-3, MMP-13 and RANKL expressions in cartilage, increased BMD, BV/TV, and decreased Tb.Sp in subchondral bone. Conversely, activation of α2A-adrenoreceptor intensified aforementioned degenerative changes in UAC rats. It is concluded that activation of α2A-adrenergic signal in chondrocytes promotes TMJ degenerative remodelling by chondrocyte-mediated pro-catabolic activities. PMID:27452863

  16. Removal torque of nail interlocking screws is related to screw proximity to the fracture and screw breakage.

    PubMed

    White, Alexander A; Kubacki, Meghan R; Samona, Jason; Telehowski, Paul; Atkinson, Patrick J

    2016-06-01

    Studies have shown that titanium implants can be challenging to explant due to the material's excellent biocompatibility and resulting osseointegration. Clinically, titanium alloy nail interlocking screws may require removal to dynamize a construct or revise the nail due to nonunion, infection, pain, or periprosthetic fracture. This study was designed to determine what variables influence the removal torque for titanium alloy interlocking screws. An intramedullary nail with four interlocking screws was used to stabilize a 1-cm segmental femoral defect in a canine model for 16 weeks. The animals were observed to be active following a several-day recovery after surgery. In six animals, the femora and implanted nail/screws were first tested to failure in torsion to simulate periprosthetic fracture of an implant after which the screws were then removed. In four additional animals, the screws were removed without mechanical testing. Both intraoperative insertional and extraction torques were recorded for all screws. Mechanical testing to failure broke 10/24 screws. On average, the intact screws required 70% of the insertional torque during removal while broken screws only required 16% of the insertional torque (p < 0.001). In addition, intact screws closer to the fracture required 2.8 times more removal torque than the outboard distal screw (p < 0.005). On average, the angle of rotation to peak torque was ∼80°. The peak axial load did not significantly correlate with the torque required to remove the screws. On average, the removal torque was lower than at the time of insertion, and less torque was required to remove broken screws and screws remote to the fracture. However, broken screws will require additional time to retrieve the remaining screw fragment. This study suggests that broken screws and screws in prematurely active patients will require less torque to remove. PMID:27129382

  17. Hypermobile joints

    MedlinePlus

    ... too far. In children with hypermobility syndrome, those ligaments are loose or weak. This may lead to: Arthritis, which may develop over time Dislocated joints, which is a separation of two bones where they meet at a joint Sprains and strains Children with hypermobile joints also often have flat ...

  18. Joint Disorders

    MedlinePlus

    A joint is where two or more bones come together, like the knee, hip, elbow, or shoulder. Joints can be damaged by many types of injuries or diseases, including Arthritis - inflammation of a joint. It causes pain, stiffness, and swelling. Over time, ...

  19. P2X and NMDA receptor involvement in temporomandibular joint-evoked reflex activity in rat jaw muscles.

    PubMed

    Watanabe, T; Tsuboi, Y; Sessle, B J; Iwata, K; Hu, J W

    2010-07-30

    We have previously shown that injection of the excitatory amino glutamate into the rat temporomandibular joint (TMJ) evokes reflex activity in both anterior digastric (DIG) and masseter (MASS) muscles that can be attenuated by prior TMJ injection of an N-methyl-d-aspartate (NMDA) receptor antagonist. The aim of the present study was to test if jaw muscle activity could also be evoked by P2X receptor agonist injection into the rat TMJ region and if the reflex activity could be modulated by TMJ injection of P2X receptor antagonist or NMDA receptor antagonist. The selective P2X subtype agonist alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-me ATP) and vehicle (phosphate-buffered saline) or the selective P2X antagonist, 2'-(or-3')-O-(2,4,6-trinitrophenyl) adenosine 5'-triphosphate (TNP-ATP) or the selective NMDA antagonist (+/-)-d-2-amino-5-phosphonovalerate(APV) were injected into the rat TMJ region. Electromyographic (EMG) reflex activity was recorded in both DIG and MASS muscles. Compared with the baseline EMG activity, alpha,beta-me-ATP injection into the TMJ (but not its systemic administration) following pre-injection of the vehicle significantly increased the magnitude and the duration of ipsilateral DIG and MASS EMG activity in a dose-dependent manner. The alpha,beta-me-ATP-evoked responses could be antagonized by pre-injection of TNP-ATP into the same TMJ site but contralateral TMJ injection of TNP-ATP proved ineffective. Furthermore, the alpha,beta-me-ATP-evoked responses could also be antagonized by APV injected into the same TMJ site but not by its systemic injection. These results indicate the interaction of peripheral purinergic as well as glutamatergic receptor mechanisms in the processing of TMJ nociceptive afferent inputs that evoke reflex activity in jaw muscles. PMID:20501327

  20. Atmospheric Gravitational Torque Variations Based on Various Gravity Fields

    NASA Technical Reports Server (NTRS)

    Sanchez, Braulio V.; Rowlands, David; Smith, David E. (Technical Monitor)

    2001-01-01

    Advancements in the study of the Earth's variable rate of rotation and the motion of its rotation axis have given impetus to the analysis of the torques between the atmosphere, oceans and solid Earth. The output from global general circulation models of the atmosphere (pressure, surface stress) is being used as input to the torque computations. Gravitational torque between the atmosphere, oceans and solid Earth is an important component of the torque budget. Computation of the gravitational torque involves the adoption of a gravitational model from a wide variety available. The purpose of this investigation is to ascertain to what extent this choice might influence the results of gravitational torque computations.

  1. Muscle Co-Contraction Modulates Damping and Joint Stability in a Three-Link Biomechanical Limb

    PubMed Central

    Heitmann, Stewart; Ferns, Norm; Breakspear, Michael

    2012-01-01

    Computational models of neuromotor control require forward models of limb movement that can replicate the natural relationships between muscle activation and joint dynamics without the burdens of excessive anatomical detail. We present a model of a three-link biomechanical limb that emphasizes the dynamics of limb movement within a simplified two-dimensional framework. Muscle co-contraction effects were incorporated into the model by flanking each joint with a pair of antagonist muscles that may be activated independently. Muscle co-contraction is known to alter the damping and stiffness of limb joints without altering net joint torque. Idealized muscle actuators were implemented using the Voigt muscle model which incorporates the parallel elasticity of muscle and tendon but omits series elasticity. The natural force-length-velocity relationships of contractile muscle tissue were incorporated into the actuators using ideal mathematical forms. Numerical stability analysis confirmed that co-contraction of these simplified actuators increased damping in the biomechanical limb consistent with observations of human motor control. Dynamic changes in joint stiffness were excluded by the omission of series elasticity. The analysis also revealed the unexpected finding that distinct stable (bistable) equilibrium positions can co-exist under identical levels of muscle co-contraction. We map the conditions under which bistability arises and prove analytically that monostability (equifinality) is guaranteed when the antagonist muscles are identical. Lastly we verify these analytic findings in the full biomechanical limb model. PMID:22275897

  2. Muscle co-contraction modulates damping and joint stability in a three-link biomechanical limb.

    PubMed

    Heitmann, Stewart; Ferns, Norm; Breakspear, Michael

    2011-01-01

    Computational models of neuromotor control require forward models of limb movement that can replicate the natural relationships between muscle activation and joint dynamics without the burdens of excessive anatomical detail. We present a model of a three-link biomechanical limb that emphasizes the dynamics of limb movement within a simplified two-dimensional framework. Muscle co-contraction effects were incorporated into the model by flanking each joint with a pair of antagonist muscles that may be activated independently. Muscle co-contraction is known to alter the damping and stiffness of limb joints without altering net joint torque. Idealized muscle actuators were implemented using the Voigt muscle model which incorporates the parallel elasticity of muscle and tendon but omits series elasticity. The natural force-length-velocity relationships of contractile muscle tissue were incorporated into the actuators using ideal mathematical forms. Numerical stability analysis confirmed that co-contraction of these simplified actuators increased damping in the biomechanical limb consistent with observations of human motor control. Dynamic changes in joint stiffness were excluded by the omission of series elasticity. The analysis also revealed the unexpected finding that distinct stable (bistable) equilibrium positions can co-exist under identical levels of muscle co-contraction. We map the conditions under which bistability arises and prove analytically that monostability (equifinality) is guaranteed when the antagonist muscles are identical. Lastly we verify these analytic findings in the full biomechanical limb model. PMID:22275897

  3. Estimations of One Repetition Maximum and Isometric Peak Torque in Knee Extension Based on the Relationship Between Force and Velocity.

    PubMed

    Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo

    2016-04-01

    Sugiura, Y, Hatanaka, Y, Arai, T, Sakurai, H, and Kanada, Y. Estimations of one repetition maximum and isometric peak torque in knee extension based on the relationship between force and velocity. J Strength Cond Res 30(4): 980-988, 2016-We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results. PMID:26382131

  4. Variable torque prescription: state of art.

    PubMed

    Lacarbonara, Mariano; Accivile, Ettore; Abed, Maria R; Teresa, Dinoi M; Monaco, Annalisa; Marzo, Giuseppe; Capogreco, Mario

    2015-01-01

    The variable prescription is widely described under the clinical aspect: the clinics is the result of the evolution of the state-of-the-art, aspect that is less considered in the daily literature. The state-of-the-art is the key to understand not only how we reach where we are but also to learn how to manage propely the torque, focusing on the technical and biomechanical purpos-es that led to the change of the torque values over time. The aim of this study is to update the clinicians on the aspects that affect the torque under the biomechanical sight, helping them to understand how to managing it, following the "timeline changes" in the different techniques so that the Variable Prescription Orthodontic (VPO) would be a suitable tool in every clinical case. PMID:25674173

  5. Variable Torque Prescription: State of Art.

    PubMed Central

    Lacarbonara, Mariano; Accivile, Ettore; Abed, Maria R.; Dinoi, Maria Teresa; Monaco, Annalisa; Marzo, Giuseppe; Capogreco, Mario

    2015-01-01

    The variable prescription is widely described under the clinical aspect: the clinics is the result of the evolution of the state-of-the-art, aspect that is less considered in the daily literature. The state-of-the-art is the key to understand not only how we reach where we are but also to learn how to manage propely the torque, focusing on the technical and biomechanical purpos-es that led to the change of the torque values over time. The aim of this study is to update the clinicians on the aspects that affect the torque under the biomechanical sight, helping them to understand how to managing it, following the “timeline changes” in the different techniques so that the Variable Prescription Orthodontic (VPO) would be a suitable tool in every clinical case. PMID:25674173

  6. Optimal tubular adhesive-bonded lap joint of the carbon fiber epoxy composite shaft

    NASA Astrophysics Data System (ADS)

    Kim, Ki S.; Kim, Won T.; Lee, Dai G.; Jun, Eui J.

    The effects of the adhesive thickness and the adherend surface roughness on the fatigue strength of a tubular adhesive-bonded single lap joint were investigated using fatigue test specimens whose adherends were made of S45C carbon steel. Results of fatigue tests showed that the optimal arithmetic surface roughness of the adherends is about 2 microns and the optimal adhesive thickness is about 0.15 mm. Using these values, the prototype torsional adhesive joints were manufactured for power transmission shafts of an automotive vehicle or a small helicopter, and static tests under torque were performed on a single-lap joint, a single-lap joint with scarf, a double-lap joint, and a double-lap joint with scarf. It was found that the double-lap joint was superior among the joints, in terms of torque capacity and manufacturing cost.

  7. Torque limit of PM motors for field-weakening region operation

    DOEpatents

    Royak, Semyon; Harbaugh, Mark M.

    2012-02-14

    The invention includes a motor controller and technique for controlling a permanent magnet motor. In accordance with one aspect of the present technique, a permanent magnet motor is controlled by receiving a torque command, determining a physical torque limit based on a stator frequency, determining a theoretical torque limit based on a maximum available voltage and motor inductance ratio, and limiting the torque command to the smaller of the physical torque limit and the theoretical torque limit. Receiving the torque command may include normalizing the torque command to obtain a normalized torque command, determining the physical torque limit may include determining a normalized physical torque limit, determining a theoretical torque limit may include determining a normalized theoretical torque limit, and limiting the torque command may include limiting the normalized torque command to the smaller of the normalized physical torque limit and the normalized theoretical torque limit.

  8. Ankle rehabilitation device with two degrees of freedom and compliant joint

    NASA Astrophysics Data System (ADS)

    Racu (Cazacu, C.-M.; Doroftei, I.

    2015-11-01

    We propose a rehabilitation device that we intend to be low cost and easy to manufacture. The system will ensure functionality but also have a small dimensions and low mass, considering the physiological dimensions of the foot and lower leg. To avoid injure of the ankle joint, this device is equipped with a compliant joint between the motor and mechanical transmission. The torque of this joint is intended to be adjustable, according to the degree of ankle joint damage. To choose the material and the dimensions of this compliant joint, in this paper we perform the first stress simulation. The minimum torque is calculated, while the maximum torque is given by the preliminary chosen actuator.

  9. Dynamic and static control of the human knee joint in abduction-adduction.

    PubMed

    Zhang, L Q; Wang, G

    2001-09-01

    It is unclear whether humans can voluntarily control dynamic and static properties in knee abduction-adduction, which may be important in performing functional tasks and preventing injuries, whether the main load is about the abduction axis or not. A joint-driving device was used to perturb the knee in abduction-adduction at full knee extension under both passive (muscle relaxed) and active (muscle contracted in abduction or adduction) conditions. Dynamic control properties in knee abduction-adduction were characterized by joint stiffness, viscosity, and limb inertia, and quasi-static knee torque-angle relationship was characterized by knee abduction-adduction laxity and quasi-static stiffness (at a 20Nm moment). It was found that the subjects were capable of generating net abduction and adduction moment through differential co-contraction of muscles crossing the medial and lateral sides of the knee, which helped to reduce the abduction-adduction joint laxity (p< or =0.01) and increase stiffness (p<0.027) and viscous damping. Knee abduction laxity was significantly lower than adduction laxity (p=0.043) and the quasi-static abduction stiffness was significantly higher than adduction stiffness (p<0.001). The knee joint showed significantly higher stiffness and viscosity in abduction-adduction than their counterparts in knee flexion-extension at comparable levels of joint torque (p<0.05). Similar to dynamic flexion-extension properties, the system damping ratio remained constant over different levels of contraction, indicating simplified control tasks for the central nervous system; while the natural undamped frequency increased considerably with abduction-adduction muscle contraction, presumably making the knee a quicker system during strenuous tasks involving strong muscle contraction. PMID:11506781

  10. Force/Torque Display For Telerobotic Systems

    NASA Technical Reports Server (NTRS)

    Wise, Marion A.

    1989-01-01

    Pictorial cathode-ray-tube (CRT) display of force and/or torque (F/T) data for telerobotic systems used as output monitor from multiaxis sensor or as command display. Relative positions of two circles represent forces and torques acting on object, derived from signals from F/T sensor composed of strain gauges. Graphical presentation generated on two different graphics systems, one in color and one in black and white. High-level programming facilitates use of additional convenient features in software extending usefulness of sensor data and display. Useful in laboratory experiments, monitoring performance of automated system and for present data on status of system to operator at control station.

  11. Recent Advances of Reluctance Torque Assisted Motors

    NASA Astrophysics Data System (ADS)

    Ohyama, Kazunobu

    The history of motor technology began with the discovery of electromagnetic induction by Faraday. Various kinds of motors were developed by the recent progress of the fundamental technology (magnetic structure, magnetic material, drive circuit, control method). Especially, motors using the reluctance torque have many advantages and some of them are used as high efficient motors. This paper overviews recent advances of reluctance torque assisted motors such as Switched Reluctance Motor (SRM), Synchronous Reluctance Motor (SynRM) and Interior Permanent Magnet Synchronous Motor (IPMSM).

  12. New Simple Torque-Sensorless Torque Control for Quasi-Perfect Compensation of 6th Harmonic Torque Ripple Due to Nonsinusoidal Distribution of Back EMF of PMSM

    NASA Astrophysics Data System (ADS)

    Shinnaka, Shinji; Kishida, Hideo

    This paper proposes a new torque-sensorless torque control method for permanent-magnet synchronous motors (PMSMs). The proposed method can almost perfectly compensate the 6th harmonic torque ripple that is caused by the nonsinusoidal distributions of the back EMF and rotor magnetic flux of PMSMs. The torque control system is, in principle, constructed on the basis of the vector control, but has two new dedicated speed-varying devices—a harmonic torque observer and current controller. The speed-varying harmonic torque observer can estimate the harmonic component over a wide speed range, even in the case where the produced torque is constant, and generate a suitable compensating signal. The speed-varying current controller shows stable control performance over a wide speed range, it can fully track the compensated current command containing the dc and 6th harmonic components. The effectiveness of the proposed method is examined and verified through extensive numerical experiments.

  13. Situated Uses of ICT and Mediation of Joint Activity in a Primary Education Instructional Sequence

    ERIC Educational Resources Information Center

    Coll, Cesar; Rochera, Maria J.; Colomina, Rosa

    2010-01-01

    Introduction: From a socioconstructivist and situated perspective of teaching and learning processes, the authors analyze how one teacher and her group of 19 sixth-grade pupils use ICT. The study focuses on the way these tools mediate their activity, and evaluates the tools' potential for teaching and learning innovation. Method: A case study…

  14. 77 FR 67057 - Agency Information Collection Activities: Submission for OMB Review; Joint Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-08

    ... Register (77 FR 44714) and requested public comment for 60 days on a proposal to extend, with revision, the... forms can be obtained at the FFIEC's Web site ( http://www.ffiec.gov/ffiec_report_forms.htm ). OCC: Mary... 1, 2012. Michele Meyer, Assistant Director, Legislative and Regulatory Activities Division,...

  15. Research and training activities of the Joint Institute for Aeronautics and Acoustics

    NASA Technical Reports Server (NTRS)

    Roberts, L.

    1993-01-01

    During the period October 1992 to September 1993 progress was made on each of the following tasks: (1) experimental studies of free shear flows; (2) analysis of conical flow; (3) experimental and theoretical studies of vortex flows; and (4) aircraft attitude control using active flow control devices. The details of this work was discussed with the technical and management staff at Ames Research Center.

  16. Interpersonal strategies for disturbance attenuation during a rhythmic joint motor action.

    PubMed

    Melendez-Calderon, A; Komisar, V; Burdet, E

    2015-08-01

    Helping someone carry a table is fairly easy; however, our understanding of such joint motor actions is still poorly understood. We studied how pairs of human subjects (referred to as dyads) collaborate physically to attenuate external mechanical perturbations during a target tracking task. Subjects tracked a target moving in a slow and predictable way using wrist flexion/extension movements, with and without destabilizing torque perturbations. Dyad strategies were classified using interaction torques and muscular activity. During unperturbed interactions (baseline), the dyads tended to stabilize on a particular strategy. The baseline strategy was not the same in all dyads, suggesting that the solution to the task was not global but specific to each particular dyad. After several trials of unperturbed interactions, we introduced mechanical vibrations and analyzed the adaptation process. Dyads showed a tendency to counteract the external disturbances by first increasing co-contraction within each subject (independent co-contraction), and then raising the amount of opposing interaction torques (dyadic co-contraction) with increased perturbation amplitude. The introduction of perturbations impelled dyads to abandon their unperturbed baseline strategy and adopt a more common strategy across dyads, suggesting attractor solutions. Our results establish a framework for future human-human interaction studies, and have implications in human motor control as well as human-robot and robot-robot interactions. PMID:25959343

  17. A Method for and Issues Associated with the Determination of Space Suit Joint Requirements

    NASA Technical Reports Server (NTRS)

    Matty, Jennifer E.; Aitchison, Lindsay

    2009-01-01

    In the design of a new space suit it is necessary to have requirements that define what mobility space suit joints should be capable of achieving in both a system and at the component level. NASA elected to divide mobility into its constituent parts-range of motion (ROM) and torque- in an effort to develop clean design requirements that limit subject performance bias and are easily verified. Unfortunately, the measurement of mobility can be difficult to obtain. Current technologies, such as the Vicon motion capture system, allow for the relatively easy benchmarking of range of motion (ROM) for a wide array of space suit systems. The ROM evaluations require subjects in the suit to accurately evaluate the ranges humans can achieve in the suit. However, when it comes to torque, there are significant challenges for both benchmarking current performance and writing requirements for future suits. This is reflected in the fact that torque definitions have been applied to very few types of space suits and with limited success in defining all the joints accurately. This paper discussed the advantages and disadvantages to historical joint torque evaluation methods, describes more recent efforts directed at benchmarking joint torques of prototype space suits, and provides an outline for how NASA intends to address joint torque in design requirements for the Constellation Space Suit System (CSSS).

  18. Ultrasound-detected activity in rheumatoid arthritis on methotrexate therapy: Which joints and tendons should be assessed to predict unstable remission?

    PubMed

    Janta, Iustina; Valor, Lara; De la Torre, Inmaculada; Martínez-Estupiñán, Lina; Nieto, Juan Carlos; Ovalles-Bonilla, Juan Gabriel; Martínez-Barrio, Julia; Bello, Natalia; Hinojosa, Michelle; Montoro, María; González, Carlos Manuel; López-Longo, Javier; Monteagudo, Indalecio; Carreño, Luis; Naredo, Esperanza

    2016-03-01

    The aim of the study was to investigate the predictive value of different reduced joint ultrasound (US) assessments of synovitis and tenosynovitis in relation to unstable remission in a cohort of rheumatoid arthritis (RA) patients on methotrexate therapy. Forty-seven RA patients (38 women, 9 men), being treated with methotrexate (MTX), in clinical remission as judged by their consultant rheumatologist were evaluated for disease activity according to the Disease Activity Score (DAS) 28 at baseline and 6 months. Sustained remission and unstable remission were defined according to the baseline and 6-month DAS28 and changes in RA therapy during the follow-up. Each patient underwent at baseline a B-mode and power Doppler (PD) assessment of 44 joints and 20 tendons/tendon compartments by a rheumatologist blinded to the clinical and laboratory data. B-mode synovial hypertrophy (SH), synovial PD signal, B-mode tenosynovitis, and Doppler tenosynovitis were scored 0-3. The presence and index of synovial PD signal in 44 joints [odds ratio (OR) 8.21 (p = 0.016) and OR 2.20 (p = 0.049), respectively] and in 12 joints [OR 5.82 (p = 0.041) and OR 4.19 (p = 0.020), respectively], the presence of SH in wrist and MCP joints [OR 4.79 (p = 0.045)], and the presence of synovial PD signal in wrist-MCP-ankle-MTP joints [OR 4.62 (p = 0.046)] were predictors of unstable remission. The 12-joint or wrist-hand-ankle-MTP US assessments can predict unstable remission in RA patients in apparent clinical remission being treated with MTX. PMID:26712373

  19. Work and fatigue characteristics of unsuited and suited humans during isolated isokinetic joint motions

    NASA Technical Reports Server (NTRS)

    Gonzalez, L. Javier; Maida, J. C.; Miles, E. H.; Rajulu, S. L.; Pandya, A. K.

    2002-01-01

    The effects of a pressurized suit on human performance were investigated. The suit is known as an Extra-Vehicular Mobility Unit (EMU) and is worn by astronauts while working outside their spacecraft in a low earth orbit. Isolated isokinetic joint torques of three female and three male subjects (all experienced users of the suit in 1G gravity) were measured while working at 100% and 80% of their maximum voluntary torque (MVT, which is synonymous with maximum voluntary contraction (MVC)). It was found that the average decrease in the total amount of work (the sum of the work in each repetition until fatigue) done when the subjects were wearing the EMU were 48% and 41% while working at 100% and 80% MVT, respectively. There is a clear relationship between the MVT and the time and amount of work done until fatigue. Here, the time to fatigue is defined as the ending time of the repetition for which the computed work done during that repetition dropped below 50% of the work done during the first repetition. In general the stronger joints took longer to fatigue and did more work than the weaker joints. It was found that the EMU decreases the work output at the wrist and shoulder joints the most, due to the EMU joint geometry. The EMU also decreased the joint range of motion. The average total amount of work done by the test subjects increased by 5.2% (20.4%) for the unsuited (suited) case, when the test subjects decreased the level of effort from 100% to 80% MVT. Also, the average time to fatigue increased by 9.2% (25.6%) for the unsuited (suited) case, when the test subjects decreased the level of effort from 100% to 80% MVT. It was also found that the experimentally measured torque decay could be predicted by a logarithmic equation. The absolute average errors in the predictions were found to be 18.3% and 18.9% for the unsuited and suited subjects, respectively, when working at 100% MVT, and 22.5% and 18.8% for the unsuited and suited subjects, respectively, when working

  20. Exoskeleton control for lower-extremity assistance based on adaptive frequency oscillators: adaptation of muscle activation and movement frequency.

    PubMed

    Aguirre-Ollinger, Gabriel

    2015-01-01

    In this article, we analyze a novel strategy for assisting the lower extremities based on adaptive frequency oscillators. Our aim is to use the control algorithm presented here as a building block for the control of powered lower-limb exoskeletons. The algorithm assists cyclic movements of the human extremities by synchronizing actuator torques with the estimated net torque exerted by the muscles. Synchronization is produced by a nonlinear dynamical system combining an adaptive frequency oscillator with a form of adaptive Fourier analysis. The system extracts, in real time, the fundamental frequency component of the net muscle torque acting on a specific joint. Said component, nearly sinusoidal in shape, is the basis for the assistive torque waveform delivered by the exoskeleton. The action of the exoskeleton can be interpreted as a virtual reduction in the mechanical impedance of the leg. We studied the ability of human subjects to adapt their muscle activation to the assistive torque. Ten subjects swung their extended leg while coupled to a stationary hip joint exoskeleton. The experiment yielded a significant decrease, with respect to unassisted movement, of the activation levels of an agonist/antagonist pair of muscles controlling the hip joint's motion, which suggests the exoskeleton control has potential for assisting human gait. A moderate increase in swing frequency was observed as well. We theorize that the increase in frequency can be explained by the impedance model of the assisted leg. Per this model, subjects adjust their swing frequency in order to control the amount of reduction in net muscle torque. PMID:25655955

  1. Chronic Inflammation and Neutrophil Activation as Possible Causes of Joint Diseases in Ballet Dancers

    PubMed Central

    Borges, Leandro da Silva; Santos, Vinicius Coneglian; de Moura, Nivaldo Ribeiro; Dermargos, Alexandre; Cury-Boaventura, Maria Fernanda; Gorjão, Renata; Pithon-Curi, Tania Cristina; Hatanaka, Elaine

    2014-01-01

    Herein, we investigated the effects of a ballet class on the kinetic profiles of creatine kinase (CK) and lactate dehydrogenase (LDH) activities, cytokines, complement component 3 (C3), and the concentrations of immunoglobulin (Ig), IgA and IgM, in ballerinas. We also verified neutrophil death and ROS release. Blood samples were taken from 13 dancers before, immediately after, and 18 hours after a ballet class. The ballet class increased the plasma activities of CK-total (2.0-fold) immediately after class, while the activities of CK-cardiac muscle (1.0-fold) and LDH (3.0-fold) were observed to increase 18 hours after the class. Levels of the TNF-α, IL-1β, IgG, and IgA were not affected under the study conditions. The exercise was found to induce neutrophil apoptosis (6.0-fold) 18 hours after the ballet class. Additionally, immediately after the ballet class, the neutrophils from the ballerinas were found to be less responsive to PMA stimulus. Conclusion. Ballet class was found to result in inflammation in dancers. The inflammation caused by the ballet class remained for 18 hours after the exercise. These findings are important in preventing the development of chronic lesions that are commonly observed in dancers, such as those with arthritis and synovitis. PMID:24701035

  2. Valgus torque in youth baseball pitchers: A biomechanical study.

    PubMed

    Sabick, Michelle B; Torry, Michael R; Lawton, Richard L; Hawkins, Richard J

    2004-01-01

    The purpose of this study was to determine the biomechanical and anthropometric factors contributing to elbow valgus torque during pitching. Video data of 14 youth pitchers throwing fastballs were used to calculate shoulder and elbow kinematics and kinetics. Peak elbow valgus torque averaged 18 Nm and occurred just before maximal shoulder external rotation. The magnitude of valgus torque was most closely correlated with the thrower's weight. When subject weight and height were controlled for, maximum shoulder abduction torque and maximum shoulder internal rotation torque were most strongly associated with elbow valgus torque, accounting for 85% of its variance (P <.001). When only kinematic variables were considered, maximum shoulder external rotation accounted for 33% of the variance in valgus torque. Given that the biomechanical variables correlated with peak valgus torque are not easily modifiable, limiting the number of innings pitched is likely the best way to reduce elbow injury in youth pitchers. PMID:15111908

  3. Correlation and prediction of dynamic human isolated joint strength from lean body mass

    NASA Technical Reports Server (NTRS)

    Pandya, Abhilash K.; Hasson, Scott M.; Aldridge, Ann M.; Maida, James C.; Woolford, Barbara J.

    1992-01-01

    A relationship between a person's lean body mass and the amount of maximum torque that can be produced with each isolated joint of the upper extremity was investigated. The maximum dynamic isolated joint torque (upper extremity) on 14 subjects was collected using a dynamometer multi-joint testing unit. These data were reduced to a table of coefficients of second degree polynomials, computed using a least squares regression method. All the coefficients were then organized into look-up tables, a compact and convenient storage/retrieval mechanism for the data set. Data from each joint, direction and velocity, were normalized with respect to that joint's average and merged into files (one for each curve for a particular joint). Regression was performed on each one of these files to derive a table of normalized population curve coefficients for each joint axis, direction, and velocity. In addition, a regression table which included all upper extremity joints was built which related average torque to lean body mass for an individual. These two tables are the basis of the regression model which allows the prediction of dynamic isolated joint torques from an individual's lean body mass.

  4. Spin-torque nano-emitters for magnonic applications

    NASA Astrophysics Data System (ADS)

    Ulrichs, H.; Demidov, V. E.; Demokritov, S. O.; Urazhdin, S.

    2012-04-01

    In the emerging field of magnonics, spin waves are utilized as a medium for high-speed transmission and processing of electrical signals on the nanometer scale. The implementation of high-performance magnonic devices requires efficient nano-scaled sources of spin waves. Here, we demonstrate experimentally that this goal can be accomplished by utilizing a modified design of spin-torque devices, in which the internal dipolar field is compensated in the active device area by a built-in micromagnet. We show experimentally that the proposed device geometry enables efficient emission of spin waves with a large propagation length for practical implementation of integrated magnonic circuits.

  5. Joint associations of objectively-measured sedentary behavior and physical activity with health-related quality of life

    PubMed Central

    Loprinzi, Paul D.

    2015-01-01

    No studies, to my knowledge, have examined the joint effects of physical activity and sedentary behavior on health-related quality of life (HRQOL), which was the purpose of this study. Data from the 2003–2006 National Health and Nutrition Examination Survey (NHANES) were used (N = 5,536). Moderate-to-vigorous physical activity (MVPA) and sedentary behavior were assessed using an ActiGraph 7164 accelerometer, with HRQOL assessed using the Centers for Disease Control and Prevention 4-item HRQOL index. MVPA (βadjusted = − 0.01; 95% CI: − 0.01 to − 0.004; P < 0.001), but not sedentary behavior (βadjusted = − 0.0003; 95% CI: − 0.001–0.0001; P = 0.37), was associated with HRQOL. MVPA was associated with HRQOL among those above the median (≥ 487.5 min/day) level of sedentary behavior (βadjusted = − 0.02; 95% CI: − 0.03 to − 0.01; P = 0.006; N = 2769). The results of this brief report do not demonstrate that sedentary behavior, independent of MVPA, is associated with HRQOL. The independent association of MVPA on HRQOL confirms previous work that used self-report measures of MVPA. PMID:26844174

  6. Current Status of Joint AFRL/NASA Microgravity Spray Cooling Research Activities

    NASA Technical Reports Server (NTRS)

    Michalak, Travis; Yerkes,Kirk; McQuillen, John; Golliher, Eric

    2004-01-01

    The Air Force Research Lab and the NASA Glenn Research Center are cooperatively examining spray cooling in a low and a variable gravity environment by conducting experiments principally aboard the NASA Reduced Gravity Aircraft. The objective of these research activities is to examine an effective high-heat flux, high-power thermal management technology using spray cooling for both aircraft and space-based platforms. Previous studies have demonstrated that two phase heat transfer and fluid management are issues that need to be examined. This effort has obtained preliminary results which confirm these concerns. More research is planned.

  7. Optimal torque control for SCOLE slewing maneuvers

    NASA Technical Reports Server (NTRS)

    Bainum, P. M.; Li, Feiyue

    1987-01-01

    The Spacecraft Control Laboratory Experiment (SCOLE) was slewed from one attitude to the required attitude and an integral performance index which involves the control torques was minimized. Kinematic and dynamical equations, optimal control, two-point boundary-value problems, and estimation of unknown boundary conditions are presented.

  8. Torque-balanced vibrationless rotary coupling

    DOEpatents

    Miller, Donald M.

    1980-01-01

    This disclosure describes a torque-balanced vibrationless rotary coupling for transmitting rotary motion without unwanted vibration into the spindle of a machine tool. A drive member drives a driven member using flexible connecting loops which are connected tangentially and at diametrically opposite connecting points through a free floating ring.

  9. Electric Field Driven Torque in ATP Synthase

    PubMed Central

    Miller, John H.; Rajapakshe, Kimal I.; Infante, Hans L.; Claycomb, James R.

    2013-01-01

    FO-ATP synthase (FO) is a rotary motor that converts potential energy from ions, usually protons, moving from high- to low-potential sides of a membrane into torque and rotary motion. Here we propose a mechanism whereby electric fields emanating from the proton entry and exit channels act on asymmetric charge distributions in the c-ring, due to protonated and deprotonated sites, and drive it to rotate. The model predicts a scaling between time-averaged torque and proton motive force, which can be hindered by mutations that adversely affect the channels. The torque created by the c-ring of FO drives the γ-subunit to rotate within the ATP-producing complex (F1) overcoming, with the aid of thermal fluctuations, an opposing torque that rises and falls with angular position. Using the analogy with thermal Brownian motion of a particle in a tilted washboard potential, we compute ATP production rates vs. proton motive force. The latter shows a minimum, needed to drive ATP production, which scales inversely with the number of proton binding sites on the c-ring. PMID:24040370

  10. Anatomy of a bearing torque problem

    NASA Technical Reports Server (NTRS)

    Phinney, Damon D.

    1987-01-01

    In the early 1970s, an antenna despin drive was developed for MBB solar science satellite HELIOS. A problem with high bearing drag torque that was encountered on the two flight models of this drive, after successful tests were completed on twelve bearings, an engineering model, and the qualification unit is discussed.

  11. Torque wrench allows readings from inaccessible locations

    NASA Technical Reports Server (NTRS)

    De Barnardo, M.

    1966-01-01

    Torque wrench with an adjustable drive shaft permits indicator to remain in view when used on sections of equipment with limited access. The shaft is capable of protruding from either side of the wrench head by means of spring loaded balls.

  12. Air brake-dynamometer accurately measures torque

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Air brake-dynamometer assembly combines the principles of the air turbine and the air pump to apply braking torque. The assembly absorbs and measures power outputs of rotating machinery over a wide range of shaft speeds. It can also be used as an air turbine.

  13. BOUSSOLE: A Joint CNRS-INSU, ESA, CNES, and NASA Ocean Color Calibration and Validation Activity

    NASA Technical Reports Server (NTRS)

    Antoine, David; Chami, Malik; Claustre, Herve; d'Ortenzio, Fabrizio; Morel, Andre; Becu, Guislain; Gentili, Bernard; Louis, Francis; Ras, Josephine; Roussier, Emmanuel; Scott, Alec J.; Tailliez, Dominique; Hooker, Stanford B.; Guevel, Pierre; Deste, Jean-Francois; Dempsey, Cyril; Adams, Darrell

    2006-01-01

    This report presents the Bouee pour l'acquisition de Series Optiques a Long Terme (BOUSSOLE) project, the primary objectives of which are to provide a long-term time series of optical properties in support of a) calibration and validation activities associated with satellite ocean color missions, and b) bio-optical research in oceanic waters. The following are included in the report: 1) an introduction to the rationale for establishing the project; 2) a definition of vicarious calibration and the specific requirements attached to it; 3) the organization of the project and the characteristics of the measurement site--in the northwestern Mediterranean Sea; 4) a qualitative overview of the collected data; 5) details about the buoy that was specifically designed and built for this project; 6) data collection protocols and data processing techniques; 7) a quantitative summary of the collected data, and a discussion of some sample results, including match-up analyses for the currently operational ocean color sensors, namely MERIS, SeaWiFS, and MODIS; and 8) preliminary results of the vicarious radiometric calibration of MERIS, including a tentative uncertainty budget. The results of this match-up analysis allow performance comparisons of various ocean color sensors to be performed, demonstrating the ability of the BOUSSOLE activity, i.e., combining a dedicated platform and commercial-off-the-shelf instrumentation, to provide data qualified to monitor the quality of ocean color products on the long term.

  14. [Experience in joint activities of the Central Research Institute of Tuberculosis, USSR Ministry of Health, with therapeutic-preventive institutions of a Kazakhstan rural area].

    PubMed

    Ivanova, E S; Fisher, Iu Ia; Fedorov, L P; Utepkaliev, M M; Akpanov, Z A; Temresheva, G T; Polosukhin, S M

    1991-01-01

    The joint activity of the Institute staff together with local health institutions has favoured qualified tuberculosis care to become more accessible to the rural population. Favourable changes in the epidemiological situation have been registered in a high tuberculosis incidence area. PMID:1837927

  15. The Effects of Sex, Joint Angle, and the Gastrocnemius Muscle on Passive Ankle Joint Complex Stiffness

    PubMed Central

    DeMont, Richard G.; Ryu, Keeho; Lephart, Scott M.

    2001-01-01

    Objective: To assess the effects of sex, joint angle, and the gastrocnemius muscle on passive ankle joint complex stiffness (JCS). Design and Setting: A repeated-measures design was employed using sex as a between-subjects factor and joint angle and inclusion of the gastrocnemius muscle as within-subject factors. All testing was conducted in a neuromuscular research laboratory. Subjects: Twelve female and 12 male healthy, physically active subjects between the ages of 18 and 30 years volunteered for participation in this study. The dominant leg was used for testing. No subjects had a history of lower extremity musculoskeletal injury or circulatory or neurologic disorders. Measurements: We determined passive ankle JCS by measuring resistance to passive dorsiflexion (5°·s−1) from 23° plantar flexion (PF) to 13° dorsiflexion (DF). Angular position and torque data were collected from a dynamometer under 2 conditions designed to include or reduce the contribution of the gastrocnemius muscle. Separate fourth-order polynomial equations relating angular position and torque were constructed for each trial. Stiffness values (Nm·degree−1) were calculated at 10° PF, neutral (NE), and 10° DF using the slope of the line at each respective position. Results: Significant condition-by-position and sex-by-position interactions and significant main effects for sex, position, and condition were revealed by a 3-way (sex-by-position, condition-by-position) analysis of variance. Post hoc analyses of the condition-by-position interaction revealed significantly higher stiffness values under the knee-straight condition compared with the knee-bent condition at both ankle NE and 10° DF. Within each condition, stiffness values at each position were significantly higher as the ankle moved into DF. Post hoc analysis of the sex-by-position interaction revealed significantly higher stiffness values at 10° DF in the male subjects. Post hoc analysis of the position main effect revealed

  16. Individual and joint activity of terpenoids, isolated from Calamintha nepeta extract, on Arabidopsis thaliana.

    PubMed

    Araniti, Fabrizio; Graña, Elisa; Reigosa, Manuel J; Sánchez-Moreiras, Adela M; Abenavoli, Maria Rosa

    2013-01-01

    Four terpenoids, camphor, pulegone, trans-caryophyllene and farnesene, previously found in Calamintha nepeta (L.) Savi methanolic extract and essential oils were assayed on germination and root growth of Arabidopsis thaliana (L.) Heynh. None of the terpenes, singularly or in combination, was able to inhibit the germination process. Farnesene and trans-caryophyllene caused a strong inhibitory effect on root growth, and pulegone, at the highest concentrations, reduced lateral root formation. Although the mixture of camphor-trans-caryophyllene with or without farnesene did not cause any effect on root growth, the addition of pulegone induced a marked synergistic activity. Moreover, the addition, at low concentration, of farnesene to pulegone-camphor-trans-caryophyllene mixture further increased the inhibitory effect on root elongation. These results suggested that the inhibitory effects caused by C. nepeta methanolic extract may depend on the combined action of different molecules. PMID:23972283

  17. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used...-cell or transfer standard may be used to verify the torque measurement system. (1) The master...

  18. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used...-cell or transfer standard may be used to verify the torque measurement system. (1) The master...

  19. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used...-cell or transfer standard may be used to verify the torque measurement system. (1) The master...

  20. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used...-cell or transfer standard may be used to verify the torque measurement system. (1) The master...

  1. 40 CFR 1066.240 - Torque transducer verification and calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) AIR POLLUTION CONTROLS VEHICLE-TESTING PROCEDURES Dynamometer Specifications § 1066.240 Torque transducer verification and calibration. Calibrate torque-measurement systems as described in 40 CFR 1065.310. ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Torque transducer verification...

  2. 40 CFR 1066.240 - Torque transducer verification.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Torque transducer verification. 1066... POLLUTION CONTROLS VEHICLE-TESTING PROCEDURES Dynamometer Specifications § 1066.240 Torque transducer verification. Verify torque-measurement systems by performing the verifications described in §§ 1066.270...

  3. 40 CFR 1066.240 - Torque transducer verification and calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) AIR POLLUTION CONTROLS VEHICLE-TESTING PROCEDURES Dynamometer Specifications § 1066.240 Torque transducer verification and calibration. Calibrate torque-measurement systems as described in 40 CFR 1065.310. ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Torque transducer verification...

  4. Performances improvements and torque ripple minimization for VSI fed induction machine with direct control torque.

    PubMed

    Abdelli, R; Rekioua, D; Rekioua, T

    2011-04-01

    This paper describes a torque ripple reduction technique with constant switching frequency for direct torque control (DTC) of an induction motor (IM). This method enables a minimum torque ripple control. In order to obtain a constant switching frequency and hence a torque ripple reduction, we propose a control technique for IM. It consists of controlling directly the electromagnetic torque by using a modulated hysteresis controller. The design methodology is based on space vector modulation (SVM) of electrical machines with digital vector control. MATLAB simulations supported with experimental study are used. The simulation and experimental results of this proposed algorithm show an adequate dynamic to IM; however, the research can be extended to include synchronous motors as well. The implementation of the proposed algorithm is described. It doesn't require any PI controller in the torque control loop. The hardware inverter is controlled digitally using a Texas Instruments TMS320F240 digital signal processor (DSP) with composed C codes for generating the required references. The results obtained from simulation and experiments confirmed the feasibility of the proposed strategy compared to the conventional one. PMID:21193193

  5. Nanowire Magnetoscope Reveals a Cellular Torque with Left-Right Bias.

    PubMed

    Liu, Wei; Bao, Yuanye; Lam, Miu Ling; Xu, Ting; Xie, Kai; Man, Hin Sum; Chan, Edward Y; Zhu, Ninghao; Lam, Raymond H W; Chen, Ting-Hsuan

    2016-08-23

    Cellular force regulates many types of cell mechanics and the associated physiological behaviors. Recent evidence suggested that cell motion with left-right (LR) bias may be the origin of LR asymmetry in tissue architecture. As actomyosin activity was found essential in the process, it predicts a type of cellular force that coordinates the development of LR asymmetry in tissue formation. However, due to the lack of appropriate platform, cellular force with LR bias has not yet been found. Here we report a nanowire magnetoscope that reveals a rotating force-torque-exerted by cells. Ferromagnetic nanowires were deposited and internalized by micropatterned cells. Within a uniform, horizontal magnetic field, the nanowires that initially aligned with the magnetic field were subsequently rotated due to the cellular torque. We found that the torque is LR-biased depending on cell types. While NIH 3T3 fibroblasts and human vascular endothelial cells exhibited counterclockwise torque, C2C12 myoblasts showed torque with slight clockwise bias. Moreover, an actin ring composed of transverse arcs and radial fibers was identified as a major factor determining the LR bias of cellular torque, since the disruption of actin ring by biochemical inhibitors or elongated cell shape abrogated the counterclockwise bias of NIH 3T3 fibroblasts. Our finding reveals a LR-biased torque of single cells and a fundamental origin of cytoskeletal chirality. More broadly, we anticipate that our method will provide a different perspective on mechanics-related cell physiology and force transmission necessary for LR propagation in tissue formation. PMID:27389867

  6. Actuation of a robotic fish caudal fin for low reaction torque

    NASA Astrophysics Data System (ADS)

    Yun, Dongwon; Kim, Kyung-Soo; Kim, Soohyun; Kyung, Jinho; Lee, Sunghee

    2011-07-01

    In this paper, a novel caudal fin for actuating a robotic fish is presented. The proposed caudal fin waves in a vertical direction with a specific spatial shape, which is determined by a so-called shape factor. For a specific shape factor, a traveling wave with a vertical phase difference is formed on a caudal fin during fin motion. It will be shown by the analysis that the maximum reaction torque at the joint of a caudal fin varies depending on the shape factors. Compared with a conventional plate type caudal fin, the proposed fin with a shape factor of 2π can eliminate the reaction torque perfectly, while keeping the propulsion force unchanged. The benefits of the proposed fin will be demonstrated by experiments.

  7. Assessment of the Breakaway Torque at the Posterior Pelvic Ring in Human Cadavers

    PubMed Central

    Bastian, Johannes Dominik; Bergmann, Mathias; Schwyn, Ronald; Keel, Marius Johann Baptist; Benneker, Lorin Michael

    2015-01-01

    ABSTRACT Purpose: To enhance the diminished screw purchase in cancellous, osteoporotic bone following the fixation of posterior pelvic ring injuries by iliosacral screws an increased bone-implant contact area using modificated screws, techniques or bone cement may become necessary. The aim of the study was to identify sites within the pathway of iliosacral screws requiring modifications of the local bone or the design of instrumentations placed at this site. Materials and Methods: The breakaway torque was measured mechanically at the iliosacral joint (“ISJ”), the sacral lateral mass (“SLM”) and the center of the S1 (“CS1”), at a superior and an inferior site under fluoroscopic control on five human cadaveric specimens (3 female; mean age 87 years, range: 76–99) using the DensiProbe™Spine device. Results: The measured median (range) breakaway torque was 0.63 Nm (0.31–2.52) at the “iliosacral joint”, 0.14 Nm (0.05–1.22) at the “sacral lateral mass”, 0.57 Nm (0.05–1.42) at the “S1 center.” The “sacral lateral mass” breakaway torque was lower than compared to that at the “iliosacral joint” (p < .001) or “S1 center” (p < .001). The median (range) breakaway torque measured at all superior measurement points was 0.52 Nm (0.10–2.52), and 0.48 Nm (0.05–1.18) at all inferior sites. The observed difference was statistically significant (p < .05). Conclusions: The lateral mass of the sacrum provides the lowest bone quality for implant anchorage. Iliosacral screws should be placed as superior as safely possible, should bridge the iliosacral joint and may allow for cement application at the lateral mass of the sacrum through perforations. PMID:26270866

  8. Torque ripple in a Darrieus, vertical axis wind turbine

    SciTech Connect

    Reuter, R.C. Jr.

    1980-01-01

    Interaction between a steady wind and a rotating, Darrieus, vertical axis wind turbine produces time periodic aerodynamic loads which cause time dependent torque variations, referred to as torque ripple, to occur in the mechanical link between the turbine and the electrical generator. There is concern for the effect of torque ripple upon fatigue life of drive train components and upon power quality. An analytical solution characterizing the phenomenon of torque ripple has been obtained which is based upon a Fourier expansion of the time dependent features of the problem. Numerical results for torque ripple, some experimental data, determination of acceptable levels and methods of controlling it, are presented and discussed.

  9. Methods of torque ripple reduction for flux reversal motor

    NASA Astrophysics Data System (ADS)

    Vakil, Gaurang; Sheth, N. K.; Miller, David

    2009-04-01

    This paper presents two-dimensional finite element based results for various methods of torque ripple reduction in flux-reversal motors. The effects of variation in magnet and rotor pole heights, rotor pole skewing, and multiple teeth per rotor pole on the cogging torque, developed torque, torque ripple, and phase inductance and also an optimum value of the magnet and rotor pole heights, skew angle, and choice of teeth per rotor pole with the teeth depth resulting in torque ripple reduction are presented.

  10. Effect of material flow on joint strength in activation spot joining of Al alloy and steel sheets

    NASA Astrophysics Data System (ADS)

    Watanabe, Goro; Yogo, Yasuhiro; Takao, Hisaaki

    2014-08-01

    A new joining method for dissimilar metal sheets was developed where a rotated consumable rod of Al alloy is pressed onto an Al alloy sheet at the part overlapped with a mild steel sheet. The metal flow in the joining region is increased by the through-hole in the Al sheet and consumable Al rod. The rod creates the joint interface and pads out of the thinly joined parts through pressing. This produces a higher joint strength than that of conventional friction stir spot welding. Measurements of the joint interface showed the presence of a 5-10 nm thick amorphous layer consisting of Al and Mg oxides.

  11. Ceramic joints

    DOEpatents

    Miller, Bradley J.; Patten, Jr., Donald O.

    1991-01-01

    Butt joints between materials having different coefficients of thermal expansion are prepared having a reduced probability of failure of stress facture. This is accomplished by narrowing/tapering the material having the lower coefficient of thermal expansion in a direction away from the joint interface and not joining the narrow-tapered surface to the material having the higher coefficient of thermal expansion.

  12. Independent and joint effects of personality on intentions to become an active participant in local union activities in Canada.

    PubMed

    McPhee, Deborah M; Sears, Greg J; Wiesner, Willi H

    2014-01-01

    Drawing on the theory of planned behavior (TPB), this field study (N = 282) investigates the impact of two focal personality traits, extraversion and conscientiousness, on employees' attitudes and intentions to actively participate in their local union. Consistent with the TPB, subjective norms, perceived behavioral control, and attitudes toward participation each explained unique variance in union participation intentions. Furthermore, results revealed that extraversion was positively related, and conscientiousness was negatively related to participation intentions, with attitudes toward participation mediating these effects. A significant interaction between extraversion and conscientiousness was also observed, such that introverted workers higher in conscientiousness were less inclined to express positive attitudes toward union participation. Overall, these results provide support for the utility of the TPB in predicting union participation intentions and highlight the vital role that personality traits may play in determining union participation attitudes and intentions. PMID:24684076

  13. Effects of bolt torque and contact resistance on the performance of the polymer electrolyte membrane electrolyzers

    NASA Astrophysics Data System (ADS)

    Selamet, Omer F.; Ergoktas, M. Said

    2015-05-01

    The effect of bolt torque and contact resistance on the performance of Proton Exchange Membrane (PEM) Electrolyzers are investigated by a 50 cm2 cell. The cell is designed and manufactured in house. The performance and contact resistance of the cell with three different gasket materials for demanding bolt torques are measured. The pressure distribution inside the cell is obtained by using pressure sensitive films. The pressure acting on the membrane electrode assembly (MEA) is calculated by analyzing and quantifying intensities of pressure film images. 3D plots of pressure distribution for predefined bolt torque values are obtained to understand the pressure distribution over the active area. The performance of the cell is enhanced when bolt torque is increased. However, beyond a value, relatively weak cell components such as diffusion layers are damaged and performance loss is observed due to the mass transfer limitations. The best efficiency is reached at 15 Nm bolt torque for Polytetrafluoroethylene (PTFE) and Ethylene Propylene Diene Monomer (EPDM) gaskets. For silicon gasket best efficiency is reached at 15 Nm at lower current densities and at 10 Nm at higher current densities. Increasing clamping pressure is found to be developing more contact points between the interfaces and results in decrease in contact resistance inside the cell.

  14. Can the self-propulsion of anisotropic microswimmers be described by using forces and torques?

    PubMed

    ten Hagen, Borge; Wittkowski, Raphael; Takagi, Daisuke; Kümmel, Felix; Bechinger, Clemens; Löwen, Hartmut

    2015-05-20

    The self-propulsion of artificial and biological microswimmers (or active colloidal particles) has often been modelled by using a force and a torque entering into the overdamped equations for the Brownian motion of passive particles. This seemingly contradicts the fact that a swimmer is force-free and torque-free, i.e. that the net force and torque on the particle vanish. Using different models for mechanical and diffusiophoretic self-propulsion, we demonstrate here that the equations of motion of microswimmers can be mapped onto those of passive particles with the shape-dependent grand resistance matrix and formally external effective forces and torques. This is consistent with experimental findings on the circular motion of artificial asymmetric microswimmers driven by self-diffusiophoresis. The concept of effective self-propulsion forces and torques significantly facilitates the understanding of the swimming paths, e.g. for a microswimmer under gravity. However, this concept has its limitations when the self-propulsion mechanism of a swimmer is disturbed either by another particle in its close vicinity or by interactions with obstacles, such as a wall. PMID:25923010

  15. Can the self-propulsion of anisotropic microswimmers be described by using forces and torques?

    NASA Astrophysics Data System (ADS)

    ten Hagen, Borge; Wittkowski, Raphael; Takagi, Daisuke; Kümmel, Felix; Bechinger, Clemens; Löwen, Hartmut

    2015-05-01

    The self-propulsion of artificial and biological microswimmers (or active colloidal particles) has often been modelled by using a force and a torque entering into the overdamped equations for the Brownian motion of passive particles. This seemingly contradicts the fact that a swimmer is force-free and torque-free, i.e. that the net force and torque on the particle vanish. Using different models for mechanical and diffusiophoretic self-propulsion, we demonstrate here that the equations of motion of microswimmers can be mapped onto those of passive particles with the shape-dependent grand resistance matrix and formally external effective forces and torques. This is consistent with experimental findings on the circular motion of artificial asymmetric microswimmers driven by self-diffusiophoresis. The concept of effective self-propulsion forces and torques significantly facilitates the understanding of the swimming paths, e.g. for a microswimmer under gravity. However, this concept has its limitations when the self-propulsion mechanism of a swimmer is disturbed either by another particle in its close vicinity or by interactions with obstacles, such as a wall.

  16. Torque generated by the flagellar motor of Escherichia coli.

    PubMed Central

    Berg, H C; Turner, L

    1993-01-01

    Cells of the bacterium Escherichia coli were tethered and spun in a high-frequency rotating electric field at a series of discrete field strengths. This was done first at low field strengths, then at field strengths generating speeds high enough to disrupt motor function, and finally at low field strengths. Comparison of the initial and final speed versus applied-torque plots yielded relative motor torque. For backward rotation, motor torque rose steeply at speeds close to zero, peaking, on average, at about 2.2 times the stall torque. For forward rotation, motor torque remained approximately constant up to speeds of about 60% of the zero-torque speed. Then the torque dropped linearly with speed, crossed zero, and reached a minimum, on average, at about -1.7 times the stall torque. The zero-torque speed increased with temperature (about 90 Hz at 11 degrees C, 140 Hz at 16 degrees C, and 290 Hz at 23 degrees C), while other parameters remained approximately constant. Sometimes the motor slipped at either extreme (delivered constant torque over a range of speeds), but eventually it broke. Similar results were obtained whether motors broke catastrophically (suddenly and completely) or progressively or were de-energized by brief treatment with an uncoupler. These results are consistent with a tightly coupled ratchet mechanism, provided that elastic deformation of force-generating elements is limited by a stop and that mechanical components yield at high applied torques. PMID:8298044

  17. Joint Estimation of Activity and Attenuation in Whole-Body TOF PET/MRI Using Constrained Gaussian Mixture Models.

    PubMed

    Mehranian, Abolfazl; Zaidi, Habib

    2015-09-01

    It has recently been shown that the attenuation map can be estimated from time-of-flight (TOF) PET emission data using joint maximum likelihood reconstruction of attenuation and activity (MLAA). In this work, we propose a novel MRI-guided MLAA algorithm for emission-based attenuation correction in whole-body PET/MR imaging. The algorithm imposes MR spatial and CT statistical constraints on the MLAA estimation of attenuation maps using a constrained Gaussian mixture model (GMM) and a Markov random field smoothness prior. Dixon water and fat MR images were segmented into outside air, lung, fat and soft-tissue classes and an MR low-intensity (unknown) class corresponding to air cavities, cortical bone and susceptibility artifacts. The attenuation coefficients over the unknown class were estimated using a mixture of four Gaussians, and those over the known tissue classes using unimodal Gaussians, parameterized over a patient population. To eliminate misclassification of spongy bones with surrounding tissues, and thus include them in the unknown class, we heuristically suppressed fat in water images and also used a co-registered bone probability map. The proposed MLAA-GMM algorithm was compared with the MLAA algorithms proposed by Rezaei and Salomon using simulation and clinical studies with two different tracer distributions. The results showed that our proposed algorithm outperforms its counterparts in suppressing the cross-talk and scaling problems of activity and attenuation and thus produces PET images of improved quantitative accuracy. It can be concluded that the proposed algorithm effectively exploits the MR information and can pave the way toward accurate emission-based attenuation correction in TOF PET/MRI. PMID:25769148

  18. Joint association of physical activity/screen time and diet on CVD risk factors in 10-year-old children.

    PubMed

    Drenowatz, Clemens; Carlson, Joseph J; Pfeiffer, Karin A; Eisenmann, Joey C

    2012-12-01

    The increasing prevalence of childhood overweight and obesity has been associated with an increased risk for cardiovascular disease (CVD). While several studies examined the effect of single behaviors such as physical activity (PA), sedentary behavior or diet on CVD risk, there is a lack of research on combined associations, specifically in children. Therefore, the purpose of this study was to examine the joint association of PA or screen time (ST) and diet on CVD risk factors in children. PA, STand diet were assessed via questionnaire in 210 fifth grade students (age: 10.6 ± 0.4 years). The healthy eating index (HEI) was subsequently calculated as indicator for diet quality. Height, weight, % body fat, and resting blood pressure were measured according to standard procedures and blood samples obtained via fingerprick were assayed for blood lipids. Total cholesterol HDL ratio (TC:HDL), mean arterial pressure (MAP), and % body fat were used as indicators of CVD risk. 55% of children did not meet current PA recommendations on at least 5 days/week and 70% exceeded current recommendations for ST. Further, only 2.5% possessed a "good" diet (HEI> 80). There was no significant association of PA or STand diet on CVD risk score. Neither TC:HDL, MAP, and % body fat nor the total CVD risk score was significantly correlated with diet, PA, or ST. Children in the high PA group, however, had significantly better diet scores. Despite the fact that self-reported PA, ST, or dietary intake were not directly related to CVD risk in this sample, higher activity levels were associated with a healthier diet and lower ST indicating an overall healthier lifestyle of this subgroup. PMID:23224418

  19. Pelvic Belt Effects on Pelvic Morphometry, Muscle Activity and Body Balance in Patients with Sacroiliac Joint Dysfunction

    PubMed Central

    Soisson, Odette; Lube, Juliane; Germano, Andresa; Hammer, Karl-Heinz; Josten, Christoph; Sichting, Freddy; Winkler, Dirk; Milani, Thomas L.; Hammer, Niels

    2015-01-01

    Introduction The sacroiliac joint (SIJ) is frequently involved in low back and pelvic girdle pain. However, morphometrical and functional characteristics related to SIJ pain are poorly defined. Pelvic belts represent one treatment option, but evidence still lacks as to their pain-reducing effects and the mechanisms involved. Addressing these two issues, this case-controlled study compares morphometric, functional and clinical data in SIJ patients and healthy controls and evaluates the effects of short-term pelvic belt application. Methods Morphometric and functional data pertaining to pelvic belt effects were compared in 17 SIJ patients and 17 controls. Lumbar spine and pelvis morphometries were obtained from 3T magnetic resonance imaging. Functional electromyography data of pelvis and leg muscles and center of pressure excursions were measured in one-leg stance. The numerical rating scale was used to evaluate immediate pain-reducing effects. Results Pelvic morphometry was largely unaltered in SIJ patients and also by pelvic belt application. The angle of lumbar lateral flexion was significantly larger in SIJ patients without belt application. Muscle activity and center of pressure were unaffected by SIJ pain or by belt application in one-leg stance. Nine of 17 patients reported decreased pain intensities under moderate belt application, four reported no change and four reported increased pain intensity. For the entire population investigated here, this qualitative description was not confirmed on a statistical significant level. Discussion Minute changes were observed in the alignment of the lumbar spine in the frontal plane in SIJ patients. The potential pain-decreasing effects of pelvic belts could not be attributed to altered muscle activity, pelvic morphometry or body balance in a static short-term application. Long-term belt effects will therefore be of prospective interest. PMID:25781325

  20. Spin-orbit-torque engineering via oxygen manipulation

    NASA Astrophysics Data System (ADS)

    Qiu, Xuepeng; Narayanapillai, Kulothungasagaran; Wu, Yang; Deorani, Praveen; Yang, Dong-Hyuk; Noh, Woo-Suk; Park, Jae-Hoon; Lee, Kyung-Jin; Lee, Hyun-Woo; Yang, Hyunsoo

    2015-05-01

    Spin transfer torques allow the electrical manipulation of magnetization at room temperature, which is desirable in spintronic devices such as spin transfer torque memories. When combined with spin-orbit coupling, they give rise to spin-orbit torques, which are a more powerful tool for controlling magnetization and can enrich device functionalities. The engineering of spin-orbit torques, based mostly on the spin Hall effect, is being intensely pursued. Here, we report that the oxidation of spin-orbit-torque devices triggers a new mechanism of spin-orbit torque, which is about two times stronger than that based on the spin Hall effect. We thus introduce a way to engineer spin-orbit torques via oxygen manipulation. Combined with electrical gating of the oxygen level, our findings may also pave the way towards reconfigurable logic devices.