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  1. Running with a load increases leg stiffness.

    Science.gov (United States)

    Silder, Amy; Besier, Thor; Delp, Scott L

    2015-04-13

    Spring-mass models have been used to characterize running mechanics and leg stiffness in a variety of conditions, yet it remains unknown how running while carrying a load affects running mechanics and leg stiffness. The purpose of this study was to test the hypothesis that running with a load increases leg stiffness. Twenty-seven subjects ran at a constant speed on a force-measuring treadmill while carrying no load, and while wearing weight vests loaded with 10%, 20%, and 30% of body weight. We measured lower extremity motion and created a scaled musculoskeletal model of each subject, which we used to estimate lower extremity joint angles and leg length. We estimated dimensionless leg stiffness as the ratio of the peak vertical ground reaction force (normalized to body weight) and the change in stance phase leg length (normalized to leg length at initial foot contact). Leg length was calculated as the distance from the center of the pelvis to the center-of-pressure under the foot. We found that dimensionless leg stiffness increased when running with load (p=0.001); this resulted from an increase in the peak vertical ground reaction force (pleg length (p=0.025). When running with load, subjects had longer ground contact times (pleg stiffness to accommodate an added load. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Leg and Joint Stiffness in Children with Spastic Diplegic Cerebral Palsy during Level Walking.

    Science.gov (United States)

    Wang, Ting-Ming; Huang, Hsing-Po; Li, Jia-Da; Hong, Shih-Wun; Lo, Wei-Ching; Lu, Tung-Wu

    2015-01-01

    Individual joint deviations are often identified in the analysis of cerebral palsy (CP) gait. However, knowledge is limited as to how these deviations affect the control of the locomotor system as a whole when striving to meet the demands of walking. The current study aimed to bridge the gap by describing the control of the locomotor system in children with diplegic CP in terms of their leg stiffness, both skeletal and muscular components, and associated joint stiffness during gait. Twelve children with spastic diplegia CP and 12 healthy controls walked at a self-selected pace in a gait laboratory while their kinematic and forceplate data were measured and analyzed during loading response, mid-stance, terminal stance and pre-swing. For calculating the leg stiffness, each of the lower limbs was modeled as a non-linear spring, connecting the hip joint center and the corresponding center of pressure, with varying stiffness that was calculated as the slope (gradient) of the axial force vs. the deformation curve. The leg stiffness was further decomposed into skeletal and muscular components considering the alignment of the lower limb. The ankle, knee and hip of the limb were modeled as revolute joints with torsional springs whose stiffness was calculated as the slope of the moment vs. the angle curve of the joint. Independent t-tests were performed for between-group comparisons of all the variables. The CP group significantly decreased the leg stiffness but increased the joint stiffness during stance phase, except during terminal stance where the leg stiffness was increased. They appeared to rely more on muscular contributions to achieve the required leg stiffness, increasing the muscular demands in maintaining the body posture against collapse. Leg stiffness plays a critical role in modulating the kinematics and kinetics of the locomotor system during gait in the diplegic CP.

  3. Leg and Joint Stiffness in Children with Spastic Diplegic Cerebral Palsy during Level Walking.

    Directory of Open Access Journals (Sweden)

    Ting-Ming Wang

    Full Text Available Individual joint deviations are often identified in the analysis of cerebral palsy (CP gait. However, knowledge is limited as to how these deviations affect the control of the locomotor system as a whole when striving to meet the demands of walking. The current study aimed to bridge the gap by describing the control of the locomotor system in children with diplegic CP in terms of their leg stiffness, both skeletal and muscular components, and associated joint stiffness during gait. Twelve children with spastic diplegia CP and 12 healthy controls walked at a self-selected pace in a gait laboratory while their kinematic and forceplate data were measured and analyzed during loading response, mid-stance, terminal stance and pre-swing. For calculating the leg stiffness, each of the lower limbs was modeled as a non-linear spring, connecting the hip joint center and the corresponding center of pressure, with varying stiffness that was calculated as the slope (gradient of the axial force vs. the deformation curve. The leg stiffness was further decomposed into skeletal and muscular components considering the alignment of the lower limb. The ankle, knee and hip of the limb were modeled as revolute joints with torsional springs whose stiffness was calculated as the slope of the moment vs. the angle curve of the joint. Independent t-tests were performed for between-group comparisons of all the variables. The CP group significantly decreased the leg stiffness but increased the joint stiffness during stance phase, except during terminal stance where the leg stiffness was increased. They appeared to rely more on muscular contributions to achieve the required leg stiffness, increasing the muscular demands in maintaining the body posture against collapse. Leg stiffness plays a critical role in modulating the kinematics and kinetics of the locomotor system during gait in the diplegic CP.

  4. Leg stiffness during sprinting in transfemoral amputees with running-specific prosthesis.

    Science.gov (United States)

    Sano, Yoko; Makimoto, Atsushi; Hashizume, Satoru; Murai, Akihiko; Kobayashi, Yoshiyuki; Takemura, Hiroshi; Hobara, Hiroaki

    2017-07-01

    Carbon fiber running-specific prostheses are designed to reproduce the spring-like stepping behavior of individuals similar to springs loaded by the entire body mass (i.e. spring-mass model). The aim of this study was to test whether leg stiffness would be modulated differently between intact and prosthetic legs in transfemoral amputees wearing RSP during sprinting. Eight unilateral transfemoral amputees performed maximum sprinting along an indoor overground runway. Leg stiffness was calculated from kinetic and kinematic data in intact and prosthetic legs. The results showed that leg stiffness was for the prosthetic limb approximately 12% decreased compared to the intact limb. Although there was no difference in leg compression between the legs, maximal vertical ground reaction force was significantly greater in the intact leg than in the prosthetic one. These results indicate that asymmetric modulation of leg stiffness in transfemoral amputees with running-specific prostheses is mainly associated with asymmetric ground reaction force. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Leg stiffness and sprint ability in amputee sprinters.

    Science.gov (United States)

    Hobara, Hiroaki; Tominaga, Shuichi; Umezawa, Shingo; Iwashita, Koudai; Okino, Atsuo; Saito, Taku; Usui, Fumio; Ogata, Toru

    2012-09-01

    Understanding leg stiffness (K (leg)) in amputee sprinters is important for the evaluation of their sprint ability and development of running-specific prostheses (RSP). To investigate K (leg) during hopping in amputee sprinters. Cross-sectional study. Seven transtibial (TT) and seven transfemoral (TF) amputee sprinters, as well as seven non-active able-bodied subjects, performed one-legged hopping matching metronome beats at 2.2 Hz. Amputees hopped on their sound limb whereas able-bodied (AB) subjects hopped on their dominant limb. Using a spring-mass model, K (leg) was calculated from the subjects' body mass, ground contact and flight times. Both TT and TF sprinters demonstrated significantly higher K (leg) than AB subjects. K (leg) during hopping on the sound leg significantly correlated with personal records attained in a 100-m sprint in both TT (r = -0.757) and TF sprinters (r = -0.855). The results of the present study suggest that amputee sprinters have a greater K (leg) during hopping than inactive non-amputees, and that their sprint ability can be predicted from the K (leg) during hopping at 2.2 Hz on the sound limb.

  6. Joint variable stiffness of musculoskeletal leg mechanism for quadruped robot

    OpenAIRE

    Lei, J; Zhu, J; Xie, P; Tokhi, MO

    2017-01-01

    © The Author(s) 2017. When the quadruped robot is in locomotion such as jumping and running with higher speed, there is non-continuous contact force between the foot and the environment inevitably. In order to achieve the flexible force interaction of the bionic legs with the environment, it is necessary to analyze the joint angular stiffness of the bionic leg. In this article, based on the designing principles of the bionics, light-weighted, and flexible, a kind of musculoskeletal bionic leg...

  7. Music decreases aortic stiffness and wave reflections.

    Science.gov (United States)

    Vlachopoulos, Charalambos; Aggelakas, Angelos; Ioakeimidis, Nikolaos; Xaplanteris, Panagiotis; Terentes-Printzios, Dimitrios; Abdelrasoul, Mahmoud; Lazaros, George; Tousoulis, Dimitris

    2015-05-01

    Music has been related to cardiovascular health and used as adjunct therapy in patients with cardiovascular disease. Aortic stiffness and wave reflections are predictors of cardiovascular risk. We investigated the short-term effect of classical and rock music on arterial stiffness and wave reflections. Twenty healthy individuals (22.5±2.5 years) were studied on three different occasions and listened to a 30-min music track compilation (classical, rock, or no music for the sham procedure). Both classical and rock music resulted in a decrease of carotid-femoral pulse wave velocity (PWV) immediately after the end of music listening (all pclassical or rock music in a more sustained way (nadir by 6.0% and 5.8%, respectively, at time zero post-music listening, all pmusic preference was taken into consideration, both classical and rock music had a more potent effect on PWV in classical aficionados (by 0.20 m/s, p=0.003 and 0.13 m/s, p=0.015, respectively), whereas there was no effect in rock aficionados (all p=NS). Regarding wave reflections, classical music led to a more potent response in classical aficionados (AIx decrease by 9.45%), whereas rock led to a more potent response to rock aficionados (by 10.7%, all pMusic, both classical and rock, decreases aortic stiffness and wave reflections. Effect on aortic stiffness lasts for as long as music is listened to, while classical music has a sustained effect on wave reflections. These findings may have important implications, extending the spectrum of lifestyle modifications that can ameliorate arterial function. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. Stiffness Model of a 3-DOF Parallel Manipulator with Two Additional Legs

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    Guang Yu

    2014-10-01

    Full Text Available This paper investigates the stiffness modelling of a 3-DOF parallel manipulator with two additional legs. The stiffness model in six directions of the 3-DOF parallel manipulator with two additional legs is derived by performing condensation of DOFs for the joint connection and treatment of the fixed-end connections. Moreover, this modelling method is used to derive the stiffness model of the manipulator with zero/one additional legs. Two performance indices are given to compare the stiffness of the parallel manipulators with two additional legs with those of the manipulators with zero/one additional legs. The method not only can be used to derive the stiffness model of a redundant parallel manipulator, but also to model the stiffness of non-redundant parallel manipulators.

  9. Influence of running velocity on vertical, leg and joint stiffness : modelling and recommendations for future research.

    Science.gov (United States)

    Brughelli, Matt; Cronin, John

    2008-01-01

    Human running can be modelled as either a spring-mass model or multiple springs in series. A force is required to stretch or compress the spring, and thus stiffness, the variable of interest in this paper, can be calculated from the ratio of this force to the change in spring length. Given the link between force and length change, muscle stiffness and mechanical stiffness have been areas of interest to researchers, clinicians, and strength and conditioning practitioners for many years. This review focuses on mechanical stiffness, and in particular, vertical, leg and joint stiffness, since these are the only stiffness types that have been directly calculated during human running. It has been established that as running velocity increases from slow-to-moderate values, leg stiffness remains constant while both vertical stiffness and joint stiffness increase. However, no studies have calculated vertical, leg or joint stiffness over a range of slow-to-moderate values to maximum values in an athletic population. Therefore, the effects of faster running velocities on stiffness are relatively unexplored. Furthermore, no experimental research has examined the effects of training on vertical, leg or joint stiffness and the subsequent effects on running performance. Various methods of training (Olympic style weightlifting, heavy resistance training, plyometrics, eccentric strength training) have shown to be effective at improving running performance. However, the effects of these training methods on vertical, leg and joint stiffness are unknown. As a result, the true importance of stiffness to running performance remains unexplored, and the best practice for changing stiffness to optimize running performance is speculative at best. It is our hope that a better understanding of stiffness, and the influence of running speed on stiffness, will lead to greater interest and an increase in experimental research in this area.

  10. Acute effect of stretching one leg on regional arterial stiffness in young men.

    Science.gov (United States)

    Yamato, Yosuke; Hasegawa, Natsuki; Fujie, Shumpei; Ogoh, Shigehiko; Iemitsu, Motoyuki

    2017-06-01

    Our previous study demonstrated that a single bout of stretching exercises acutely reduced arterial stiffness. We hypothesized that this acute vascular response is due to regional mechanical stimulation of the peripheral arteries. To test this hypothesis, we examined the effect of a single bout of passive one leg stretching on arterial stiffness, comparing the stretched and the non-stretched leg in the same subject. Twenty-five healthy young men (20.9 ± 0.3 years, 172.5 ± 1.4 cm, 64.1 ± 1.2 kg) volunteered for the study. Subjects underwent a passive calf stretching on one leg (six repetitions of 30-s static stretch with a 10-s recovery). Pulse wave velocity (PWV, an index of arterial stiffness), blood pressure (BP), and heart rate (HR) were measured before and immediately, 15, and 30 min after the stretching. Femoral-ankle PWV (faPWV) in the stretched leg was significantly decreased from baseline (835.0 ± 15.9 cm/s) to immediately (802.9 ± 16.8 cm/s, P leg was not significantly altered at any time. Brachial-ankle PWV (baPWV) also showed similar responses with faPWV, but this response was not significant. Additionally, the passive stretching did not alter carotid-femoral PWV (cfPWV). These results suggest that mechanical stimulation to peripheral arteries as induced by static passive stretch may modulate arterial wall properties directly, rather than resulting in a systemic effect.

  11. The leg stiffnesses animals use may improve the stability of locomotion.

    Science.gov (United States)

    Shen, ZhuoHua; Seipel, Justin

    2015-07-21

    Despite a wide diversity of running animals, their leg stiffness normalized by animal size and weight (a relative leg stiffness) resides in a narrow range between 7 and 27. Here we determine if the stability of locomotion could be a driving factor for the tight distribution of animal leg stiffness. We simulated an established physics-based model (the actuated Spring-Loaded Inverted Pendulum model) of animal running and found that, with the same energetic cost, perturbations to locomotion are optimally corrected when relative leg stiffness is within the biologically observed range. Here we show that the stability of locomotion, in combination with energetic cost, could be a significant factor influencing the nearly universally observed animal relative leg stiffness range. The energetic cost of locomotion has been widely acknowledged as influencing the evolution of physiology and locomotion behaviors. Specifically, its potential importance for relative leg stiffness has been demonstrated. Here, we demonstrate that stability of locomotion may also be a significant factor influencing relative leg stiffness. Published by Elsevier Ltd.

  12. Leg stiffness during phases of countermovement and take-off in vertical jump.

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    Struzik, Artur; Zawadzki, Jerzy

    2013-01-01

    With respect to cyclic movements such as human gait, running or hopping, leg stiffness is a little variable parameter. The aim of this study was to investigate changes in leg stiffness during the phase of countermovement and take-off when performing a single maximum counter-movement jump. Kistler force plates and a BTS SMART system for comprehensive motion analysis were employed in the study. The study covered a group of 12 athletes from university basketball teams. Leg stiffness was calculated in those parts of countermovement and take-off phases where its level is relatively constant and the relationship F(Δl) is similar to linear one. Mean total stiffness (±SD) in both legs in the countermovement phase amounted to 6.5 ± 1.5 kN/m, whereas during the take-off phase this value was 6.9 ± 1 kN/m. No statistically significant differences were found between leg stiffness during the countermovement phase and takeoff phase in the study group at the level of significance set at α = 0.05. This suggests that the leg stiffness in phase of countermovement and phase of take-off are much similar to each other, despite different function of both phases. Similar to cyclic movements, leg stiffness turned out relatively constant when performing a single vertical jump. There are also reported statistically significant correlations between body mass, body height, length of lower limbs and leg stiffness. The stiffness analysed by the authors should be understood as quasi-stiffness because the measurements of ΔF(Δl) were made during transient states where inertia and dumping forces are likely to affect the final result.

  13. Application of force-length curve for determination of leg stiffness during a vertical jump.

    Science.gov (United States)

    Struzik, Artur; Zawadzki, Jerzy

    2016-01-01

    The aim of this study was to present the methodology for estimation of a leg stiffness during a countermovement jump. The question was asked whether leg stiffness in the countermovement and take-off phases are similar to each other as demonstrated in previous reports. It was also examined whether the stiffness in left lower limb is similar to the one in right lower limb. The research was conducted on 35 basketball players. Each participant performed three countermovement jumps with arm swing to the maximum height. Measurements employed a Kistlerforce plate and a BTS SMART system for motion analysis. Leg stiffness (understood as an inclination of the curve of ground reaction forces vs. length) was computed for these parts of countermovement and take-off phases where its value was relatively constant and F(Δl) relationship was similar to linear. Mean value (±SD) of total stiffness of both lower limbs in the countermovement phase was 7.1 ± 2.3 kN/m, whereas this value in the take-off phase was 7.5 ± 1 kN/m. No statistically significant differences were found between the leg stiffness in the countermovement and the take-off phases. No statistically significant differences were found during the comparison of the stiffness in the right and left lower limb. The calculation methodology allows us to estimate the value of leg stiffness based on the actual shape of F(Δl) curve rather than on extreme values of ΔF and Δl. Despite different tasks of the countermovement and the take-off phases, leg stiffness in these phases is very similar. Leg stiffness during a single vertical jump maintains a relatively constant value in the parts with a small value of acceleration.

  14. Influence of “J”-Curve Spring Stiffness on Running Speeds of Segmented Legs during High-Speed Locomotion

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    Runxiao Wang

    2016-01-01

    Full Text Available Both the linear leg spring model and the two-segment leg model with constant spring stiffness have been broadly used as template models to investigate bouncing gaits for legged robots with compliant legs. In addition to these two models, the other stiffness leg spring models developed using inspiration from biological characteristic have the potential to improve high-speed running capacity of spring-legged robots. In this paper, we investigate the effects of “J”-curve spring stiffness inspired by biological materials on running speeds of segmented legs during high-speed locomotion. Mathematical formulation of the relationship between the virtual leg force and the virtual leg compression is established. When the SLIP model and the two-segment leg model with constant spring stiffness and with “J”-curve spring stiffness have the same dimensionless reference stiffness, the two-segment leg model with “J”-curve spring stiffness reveals that (1 both the largest tolerated range of running speeds and the tolerated maximum running speed are found and (2 at fast running speed from 25 to 40/92 m s−1 both the tolerated range of landing angle and the stability region are the largest. It is suggested that the two-segment leg model with “J”-curve spring stiffness is more advantageous for high-speed running compared with the SLIP model and with constant spring stiffness.

  15. Influence of "J"-Curve Spring Stiffness on Running Speeds of Segmented Legs during High-Speed Locomotion.

    Science.gov (United States)

    Wang, Runxiao; Zhao, Wentao; Li, Shujun; Zhang, Shunqi

    2016-01-01

    Both the linear leg spring model and the two-segment leg model with constant spring stiffness have been broadly used as template models to investigate bouncing gaits for legged robots with compliant legs. In addition to these two models, the other stiffness leg spring models developed using inspiration from biological characteristic have the potential to improve high-speed running capacity of spring-legged robots. In this paper, we investigate the effects of "J"-curve spring stiffness inspired by biological materials on running speeds of segmented legs during high-speed locomotion. Mathematical formulation of the relationship between the virtual leg force and the virtual leg compression is established. When the SLIP model and the two-segment leg model with constant spring stiffness and with "J"-curve spring stiffness have the same dimensionless reference stiffness, the two-segment leg model with "J"-curve spring stiffness reveals that (1) both the largest tolerated range of running speeds and the tolerated maximum running speed are found and (2) at fast running speed from 25 to 40/92 m s -1 both the tolerated range of landing angle and the stability region are the largest. It is suggested that the two-segment leg model with "J"-curve spring stiffness is more advantageous for high-speed running compared with the SLIP model and with constant spring stiffness.

  16. Control strategy for energy-efficient bipedal walking with variable leg stiffness

    NARCIS (Netherlands)

    Visser, L.C.; Stramigioli, Stefano; Carloni, Raffaella

    In this work, we propose a hybrid model for a bipedal walker with controlled variable leg stiffness, and a control strategy for stable gait control. The control reference is a passive gait of the limit-case bipedal spring-loaded inverted pendulum model with massless feet, ensuring that the gait is

  17. Pneumatic Artificial Muscles Force Modelling and the Position and Stiffness Control on the Knee Joint of the Musculoskeletal Leg

    OpenAIRE

    Jingtao Lei; Jianmin Zhu

    2017-01-01

    Pneumatic artificial muscles (PAMs) have properties similar to biological muscle and are widely used in robotics as actuators. A musculoskeletal leg mechanism driven by PAMs is presented in this paper. The joint stiffness of the musculoskeletal bionic leg for jumping movement needs to be analysed. The synchronous control on the position and stiffness of the joint is important to improve the flexibility of leg. The accurate force model of PAM is the foundation to achieving better control and d...

  18. Neural control of leg stiffness during hopping in boys and men.

    Science.gov (United States)

    Oliver, J L; Smith, P M

    2010-10-01

    The purpose of the study was to investigate whether boys and men utilise different control strategies whilst hopping. Eleven boys (11-12yr old) and ten men completed hopping at 1.5Hz, 3.0Hz and at their preferred frequency. A footswitch measured contact and flight times, from which leg stiffness was calculated. Simultaneously, surface electromyograms (EMGs) of selected lower limb muscles were recorded and quantified for each 30ms period during the first 120ms post-ground contact. At 1.5Hz there were no differences between the groups in relative stiffness or muscle activity. At 3.0Hz men had significantly shorter contact times (P=0.013), longer flight times (P=0.002), greater relative stiffness (P=0.01) and significantly greater soleus (P=0.012) and vastus lateralis (Pboys (P=0.007), with greater leg stiffness (PBoys and men demonstrated similar control strategies when hopping at a slow frequency, but when hopping frequency increased men were able to better increase feedforward and reflex muscle activity to hop with greater relative stiffness. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  19. Contributions of Hamstring Stiffness to Straight-Leg-Raise and Sit-and-Reach Test Scores.

    Science.gov (United States)

    Miyamoto, Naokazu; Hirata, Kosuke; Kimura, Noriko; Miyamoto-Mikami, Eri

    2018-02-01

    The passive straight-leg-raise (PSLR) and the sit-and-reach (SR) tests have been widely used to assess hamstring extensibility. However, it remains unclear to what extent hamstring stiffness (a measure of material properties) contributes to PSLR and SR test scores. Therefore, we aimed to clarify the relationship between hamstring stiffness and PSLR and SR scores using ultrasound shear wave elastography. Ninety-eight healthy subjects completed the study. Each subject completed PSLR testing, and classic and modified SR testing of the right leg. Muscle shear modulus of the biceps femoris, semitendinosus, and semimembranosus was quantified as an index of muscle stiffness. The relationships between shear modulus of each muscle and PSLR or SR scores were calculated using Pearson's product-moment correlation coefficients. Shear modulus of the semitendinosus and semimembranosus showed negative correlations with the two PSLR and two SR scores (absolute r value≤0.484). Shear modulus of the biceps femoris was significantly correlated with the PSLR score determined by the examiner and the modified SR score (absolute r value≤0.308). The present findings suggest that PSLR and SR test scores are strongly influenced by factors other than hamstring stiffness and therefore might not accurately evaluate hamstring stiffness. © Georg Thieme Verlag KG Stuttgart · New York.

  20. Leg stiffness can be maintained during reactive hopping despite modified acceleration conditions.

    Science.gov (United States)

    Kramer, A; Ritzmann, R; Gruber, M; Gollhofer, A

    2012-06-26

    The aim of the present study was to evaluate reactive hops under systematically modified acceleration conditions. It was hypothesized that a high preactivity of the leg extensors and phase-specific adjustments of the leg muscle activation would compensate the alterations caused by the various acceleration levels in order to maintain a high leg stiffness, thus enabling the jumper to perform truly reactive jumps with short ground contact times despite the unaccustomed acceleration conditions. Ground reaction forces (GRF), kinematic and electromyographic data of 20 healthy subjects were recorded during reactive hopping in a special sledge jump system for seven different acceleration levels: three acceleration levels with lower than normal gravity (0.7g, 0.8g, 0.9g), one with gravitational acceleration (1g) and three with higher acceleration (1.1g, 1.2g, 1.3g). The increase of the acceleration from 0.7g to 1.3g had no significant effect on the preactivity of the leg extensors, the leg stiffness and the rate of force development. However, it resulted in increased peak GRF (+15%), longer ground contact time (+10%) and increased angular excursion at the ankle and knee joints (+3°). Throughout a wide acceleration range, the subjects were able to maintain a high leg stiffness and perform reactive hops by keeping the preactivity constantly high and adjusting the muscle activity in the later phases. In consequence, it can be concluded that the neuromuscular system can cope with different acceleration levels, at least in the acceleration range used in this study. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. The effects of stair climbing on arterial stiffness, blood pressure, and leg strength in postmenopausal women with stage 2 hypertension.

    Science.gov (United States)

    Wong, Alexei; Figueroa, Arturo; Son, Won-Mok; Chernykh, Oksana; Park, Song-Young

    2018-02-12

    Menopause is accompanied by a progressive arterial stiffening associated with increases in blood pressure (BP) and decline in muscular function. It is crucial to prevent or reduce the negative effects of menopause on vascular and muscular function by implementing appropriate lifestyle interventions, such as exercise training. We examined the effects of a stair climbing (SC) regimen on arterial stiffness (pulse wave velocity [PWV]), BP, and leg strength in postmenopausal women with stage 2 hypertension. Using a parallel experimental design, participants were randomly assigned to either SC (n = 21) or nonexercising control group (n = 20) for 12 weeks. Participants in the SC group trained 4 d/wk, climbing 192 steps 2 to 5 times/d. Participants' brachial-to-ankle PWV (baPWV), BP, and leg strength were measured at baseline and after 12 weeks of their assigned intervention. There was a significant group by time interaction (P hypertensive postmenopausal women. The decrease in arterial stiffness partially explained the improvements in SBP and leg strength. SC may be an effective intervention in the prevention and treatment of menopause/aging-related vascular complications and muscle weakness.

  2. Warm-up with a weighted vest improves running performance via leg stiffness and running economy.

    Science.gov (United States)

    Barnes, K R; Hopkins, W G; McGuigan, M R; Kilding, A E

    2015-01-01

    To determine the effects of "strides" with a weighted-vest during a warm-up on endurance performance and its potential neuromuscular and metabolic mediators. A bout of resistance exercise can enhance subsequent high-intensity performance, but little is known about such priming exercise for endurance performance. A crossover with 5-7 days between an experimental and control trial was performed by 11 well-trained distance runners. Each trial was preceded by a warm-up consisting of a 10-min self-paced jog, a 5-min submaximal run to determine running economy, and six 10-s strides with or without a weighted-vest (20% of body mass). After a 10-min recovery period, runners performed a series of jumps to determine leg stiffness and other neuromuscular characteristics, another 5-min submaximal run, and an incremental treadmill test to determine peak running speed. Clinical and non-clinical forms of magnitude-based inference were used to assess outcomes. Correlations and linear regression were used to assess relationships between performance and underlying measures. The weighted-vest condition resulted in a very-large enhancement of peak running speed (2.9%; 90% confidence limits ±0.8%), a moderate increase in leg stiffness (20.4%; ±4.2%) and a large improvement in running economy (6.0%; ±1.6%); there were also small-moderate clear reductions in cardiorespiratory measures. Relationships between change scores showed that changes in leg stiffness could explain all the improvements in performance and economy. Strides with a weighted-vest have a priming effect on leg stiffness and running economy. It is postulated the associated major effect on peak treadmill running speed will translate into enhancement of competitive endurance performance. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  3. Stiffness characteristics of compliant three segment leg with the self-stable region in slow and fast running

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Oh Seok; Ha, Sung Mok; Lee, Dong Ha [Convergence Research Center for WellnessDaegu Gyeongbuk Institute of Science and TechnologyDaegu (Korea, Republic of)

    2016-12-15

    In this paper, we propose the stiffness characteristics of compliant three segment leg that can have a self-stable region in slow and fast running. This proposition can contribute to reducing the control effort and enhancing the locomotion energy efficiency for the compliant three segment legged robot in slow and fast running. Previous research indicated that the running self-stable region of the spring-mass system is located in a relatively fast running region and that of the two segment leg is located in a relatively slow running region. In this paper, we analyze the stiffness characteristics of the spring-mass system and the two segment leg to explain the previous research results. From this analysis, we propose the stiffness characteristics of the compliant three segment leg with a self-stable region in slow and fast running. We further design the compliant three segment leg based on this proposition and check its structural stability. We examine the running self-stable region of this compliant three segment leg to determine whether it has a self-stable region in slow and fast running. We also examine the walking self-stable region of this compliant three segment leg.

  4. Pneumatic Artificial Muscles Force Modelling and the Position and Stiffness Control on the Knee Joint of the Musculoskeletal Leg

    Directory of Open Access Journals (Sweden)

    Jingtao Lei

    2017-03-01

    Full Text Available Pneumatic artificial muscles (PAMs have properties similar to biological muscle and are widely used in robotics as actuators. A musculoskeletal leg mechanism driven by PAMs is presented in this paper. The joint stiffness of the musculoskeletal bionic leg for jumping movement needs to be analysed. The synchronous control on the position and stiffness of the joint is important to improve the flexibility of leg. The accurate force model of PAM is the foundation to achieving better control and dynamic jumping performance. The experimental platform of PAM is conducted, and the static equal pressure experiments are performed to obtain the PAM force model. According to the testing data, parameter identification method is adopted to determine the force model of PAM. A simulation on the position and stiffness control of the knee joint is performed, and the simulation results show the effectiveness of the presented method.

  5. Muscle stiffness of posterior lower leg in runners with a history of medial tibial stress syndrome.

    Science.gov (United States)

    Saeki, J; Nakamura, M; Nakao, S; Fujita, K; Yanase, K; Ichihashi, N

    2018-01-01

    Previous history of medial tibial stress syndrome (MTSS) is a risk factor for MTSS relapse, which suggests that there might be some physical factors that are related to MTSS development in runners with a history of MTSS. The relationship between MTSS and muscle stiffness can be assessed in a cross-sectional study that measures muscle stiffness in subjects with a history of MTSS, who do not have pain at the time of measurement, and in those without a history of MTSS. The purpose of this study was to compare the shear elastic modulus, which is an index of muscle stiffness, of all posterior lower leg muscles of subjects with a history of MTSS and those with no history and investigate which muscles could be related to MTSS. Twenty-four male collegiate runners (age, 20.0±1.7 years; height, 172.7±4.8 cm; weight, 57.3±3.7 kg) participated in this study; 14 had a history of MTSS, and 10 did not. The shear elastic moduli of the lateral gastrocnemius, medial gastrocnemius, soleus, peroneus longus, peroneus brevis, flexor hallucis longus, flexor digitorum longus, and tibialis posterior were measured using shear wave elastography. The shear elastic moduli of the flexor digitorum longus and tibialis posterior were significantly higher in subjects with a history of MTSS than in those with no history. However, there was no significant difference in the shear elastic moduli of other muscles. The results of this study suggest that flexor digitorum longus and tibialis posterior stiffness could be related to MTSS. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. Damage severity estimation from the global stiffness decrease

    International Nuclear Information System (INIS)

    Nitescu, C; Gillich, G R; Manescu, T; Korka, Z I; Abdel Wahab, M

    2017-01-01

    In actual damage detection methods, localization and severity estimation can be treated separately. The severity is commonly estimated using fracture mechanics approach, with the main disadvantage of involving empirically deduced relations. In this paper, a damage severity estimator based on the global stiffness reduction is proposed. This feature is computed from the deflections of the intact and damaged beam, respectively. The damage is always located where the bending moment achieves maxima. If the damage is positioned elsewhere on the beam, its effect becomes lower, because the stress is produced by a diminished bending moment. It is shown that the global stiffness reduction produced by a crack is the same for all beams with a similar cross-section, regardless of the boundary conditions. One mathematical relation indicating the severity and another indicating the effect of removing damage from the beam. Measurements on damaged beams with different boundary conditions and cross-sections are carried out, and the location and severity are found using the proposed relations. These comparisons prove that the proposed approach can be used to accurately compute the severity estimator. (paper)

  7. Relationships Between Lower-Body Muscle Structure and, Lower-Body Strength, Explosiveness and Eccentric Leg Stiffness in Adolescent Athletes.

    Science.gov (United States)

    Secomb, Josh L; Nimphius, Sophia; Farley, Oliver R L; Lundgren, Lina E; Tran, Tai T; Sheppard, Jeremy M

    2015-12-01

    The purpose of the present study was to determine whether any relationships were present between lower-body muscle structure and, lower-body strength, variables measured during a countermovement jump (CMJ) and squat jump (SJ), and eccentric leg stiffness, in adolescent athletes. Thirty junior male (n = 23) and female (n = 7) surfing athletes (14.8 ± 1.7 y; 1.63 ± 0.09 m; 54.8 ± 12.1 kg) undertook lower-body muscle structure assessment with ultrasonography and performed a; CMJ, SJ and an isometric mid-thigh pull (IMTP). In addition, eccentric leg stiffness was calculated from variables of the CMJ and IMTP. Moderate to very large relationships (r = 0.46-0.73) were identified between the thickness of the vastus lateralis (VL) and lateral gastrocnemius (LG) muscles, and VL pennation angle and; peak force (PF) in the CMJ, SJ and IMTP. Additionally, moderate to large relationships (r = 0.37-0.59) were found between eccentric leg stiffness and; VL and LG thickness, VL pennation angle, and LG fascicle length, with a large relationship (r = 0.59) also present with IMTP PF. These results suggest that greater thickness of the VL and LG were related to improved maximal dynamic and isometric strength, likely due to increased hypertrophy of the extensor muscles. Furthermore, this increased thickness was related to greater eccentric leg stiffness, as the associated enhanced lower-body strength likely allowed for greater neuromuscular activation, and hence less compliance, during a stretch-shortening cycle. Key pointsGreater thickness of the VL and LG muscles were significantly related to an enhanced ability to express higher levels of isometric and dynamic strength, and explosiveness in adolescent athletes.Isometric strength underpinned performance in the CMJ and SJ in these athletes.Greater lower-body isometric strength was significantly related to eccentric leg stiffness, which is potentially the result of greater neuromuscular activation in the muscle-tendon unit.

  8. Relationships Between Lower-Body Muscle Structure and, Lower-Body Strength, Explosiveness and Eccentric Leg Stiffness in Adolescent Athletes

    Directory of Open Access Journals (Sweden)

    Josh L. Secomb, Sophia Nimphius, Oliver R.L. Farley, Lina E. Lundgren, Tai T. Tran, Jeremy M. Sheppard

    2015-12-01

    Full Text Available The purpose of the present study was to determine whether any relationships were present between lower-body muscle structure and, lower-body strength, variables measured during a countermovement jump (CMJ and squat jump (SJ, and eccentric leg stiffness, in adolescent athletes. Thirty junior male (n = 23 and female (n = 7 surfing athletes (14.8 ± 1.7 y; 1.63 ± 0.09 m; 54.8 ± 12.1 kg undertook lower-body muscle structure assessment with ultrasonography and performed a; CMJ, SJ and an isometric mid-thigh pull (IMTP. In addition, eccentric leg stiffness was calculated from variables of the CMJ and IMTP. Moderate to very large relationships (r = 0.46-0.73 were identified between the thickness of the vastus lateralis (VL and lateral gastrocnemius (LG muscles, and VL pennation angle and; peak force (PF in the CMJ, SJ and IMTP. Additionally, moderate to large relationships (r = 0.37-0.59 were found between eccentric leg stiffness and; VL and LG thickness, VL pennation angle, and LG fascicle length, with a large relationship (r = 0.59 also present with IMTP PF. These results suggest that greater thickness of the VL and LG were related to improved maximal dynamic and isometric strength, likely due to increased hypertrophy of the extensor muscles. Furthermore, this increased thickness was related to greater eccentric leg stiffness, as the associated enhanced lower-body strength likely allowed for greater neuromuscular activation, and hence less compliance, during a stretch-shortening cycle.

  9. Relationships Between Lower-Body Muscle Structure and, Lower-Body Strength, Explosiveness and Eccentric Leg Stiffness in Adolescent Athletes

    OpenAIRE

    Secomb, Josh L.; Nimphius, Sophia; Farley, Oliver R.L.; Lundgren, Lina E.; Tran, Tai T.; Sheppard, Jeremy M.

    2015-01-01

    The purpose of the present study was to determine whether any relationships were present between lower-body muscle structure and, lower-body strength, variables measured during a countermovement jump (CMJ) and squat jump (SJ), and eccentric leg stiffness, in adolescent athletes. Thirty junior male (n = 23) and female (n = 7) surfing athletes (14.8 ± 1.7 y; 1.63 ± 0.09 m; 54.8 ± 12.1 kg) undertook lower-body muscle structure assessment with ultrasonography and performed a; CMJ, SJ and an isome...

  10. Development of VariLeg, an exoskeleton with variable stiffness actuation: first results and user evaluation from the CYBATHLON 2016.

    Science.gov (United States)

    Schrade, Stefan O; Dätwyler, Katrin; Stücheli, Marius; Studer, Kathrin; Türk, Daniel-Alexander; Meboldt, Mirko; Gassert, Roger; Lambercy, Olivier

    2018-03-13

    Powered exoskeletons are a promising approach to restore the ability to walk after spinal cord injury (SCI). However, current exoskeletons remain limited in their walking speed and ability to support tasks of daily living, such as stair climbing or overcoming ramps. Moreover, training progress for such advanced mobility tasks is rarely reported in literature. The work presented here aims to demonstrate the basic functionality of the VariLeg exoskeleton and its ability to enable people with motor complete SCI to perform mobility tasks of daily life. VariLeg is a novel powered lower limb exoskeleton that enables adjustments to the compliance in the leg, with the objective of improving the robustness of walking on uneven terrain. This is achieved by an actuation system with variable mechanical stiffness in the knee joint, which was validated through test bench experiments. The feasibility and usability of the exoskeleton was tested with two paraplegic users with motor complete thoracic lesions at Th4 and Th12. The users trained three times a week, in 60 min sessions over four months with the aim of participating in the CYBATHLON 2016 competition, which served as a field test for the usability of the exoskeleton. The progress on basic walking skills and on advanced mobility tasks such as incline walking and stair climbing is reported. Within this first study, the exoskeleton was used with a constant knee stiffness. Test bench evaluation of the variable stiffness actuation system demonstrate that the stiffness could be rendered with an error lower than 30 Nm/rad. During training with the exoskeleton, both users acquired proficient skills in basic balancing, walking and slalom walking. In advanced mobility tasks, such as climbing ramps and stairs, only basic (needing support) to intermediate (able to perform task independently in 25% of the attempts) skill levels were achieved. After 4 months of training, one user competed at the CYBATHLON 2016 and was able to perform 3

  11. Effect of minimal shoes and slope on vertical and leg stiffness during running

    Directory of Open Access Journals (Sweden)

    Thibault Lussiana

    2015-06-01

    Conclusion: This study showed that kvert and kleg during running respond differently to change in footwear and/or slope. These two stiffness measures can hence provide a unique insight on the biomechanical adaptations of running under varying conditions and their respective quantification may assist in furthering our understanding of training, performance, and/or injury in this sport.

  12. Shape modification for decreasing the spring stiffness of double-plate nozzle type spacer grid spring

    International Nuclear Information System (INIS)

    Lee, K. H.; Kang, H. S.; Song, K. N.; Yun, K. H.; Kim, H. K.

    2001-01-01

    Nozzle of the double-plated grid plays the role of the spirng to support a fuel rod as well as the coolant path in grid. The nozzle was known to be necessary to reduce the spring stiffness for supporting performance. In this study, the contact analysis between the fuel rod and the newly designed nozzle was performed by ABAQUS computer code to propose the preferable shape in term of spring performance. Two small cut at the upper and lower part of the nozzle appeared to have a minor effect in decreasing the nozzle stiffness. A long slot at the center of the nozzle was turned out not only to decrease the spring constant as desired but also to increase the elastic displacement

  13. Acute decrease in the stiffness of resting muscle belly due to static stretching.

    Science.gov (United States)

    Taniguchi, K; Shinohara, M; Nozaki, S; Katayose, M

    2015-02-01

    The purpose of the study was to examine the acute effect of static stretching exercise on the resting stiffness of gastrocnemius muscle belly. Ten healthy young adults performed standing wall stretching in dorsiflexion for 1 min at a time and repeated five times. Before and after stretching, the shear modulus was measured in medial and lateral heads of the resting gastrocnemius muscle with ultrasound shear-wave elastography. After the stretching, dorsiflexion range of motion (ROM) of the ankle joint increased (P stretching, shear modulus decreased (P stretching across muscle heads. The decrease in shear modulus returned in 20 min after stretching. In the comparison group of 10 additional subjects, the standing intervention without stretching had no influence on these measures. There was a negative correlation between dorsiflexion ROM and shear modulus in either head before and after stretching. The results demonstrate the transient decreases in the stiffness of the resting gastrocnemius muscle belly and indicate that joint flexibility is greater in individuals with lower resting stiffness of the muscle belly. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Nonlinear dynamics near resonances of a rotor-active magnetic bearings system with 16-pole legs and time varying stiffness

    Science.gov (United States)

    Wu, R. Q.; Zhang, W.; Yao, M. H.

    2018-02-01

    In this paper, we analyze the complicated nonlinear dynamics of rotor-active magnetic bearings (rotor-AMB) with 16-pole legs and the time varying stiffness. The magnetic force with 16-pole legs is obtained by applying the electromagnetic theory. The governing equation of motion for rotor-active magnetic bearings is derived by using the Newton's second law. The resulting dimensionless equation of motion for the rotor-AMB system is expressed as a two-degree-of-freedom nonlinear system including the parametric excitation, quadratic and cubic nonlinearities. The averaged equation of the rotor-AMB system is obtained by using the method of multiple scales when the primary parametric resonance and 1/2 subharmonic resonance are taken into account. From the frequency-response curves, it is found that there exist the phenomena of the soft-spring type nonlinearity and the hardening-spring type nonlinearity in the rotor-AMB system. The effects of different parameters on the nonlinear dynamic behaviors of the rotor-AMB system are investigated. The numerical results indicate that the periodic, quasi-periodic and chaotic motions occur alternately in the rotor-AMB system.

  15. Dynamic elastic response prostheses alter approach angles and ground reaction forces but not leg stiffness during a start-stop task.

    Science.gov (United States)

    Haber, Cassandra Kay; Ritchie, Laura J; Strike, Siobhan C

    2018-04-01

    In a dynamic elastic response prosthesis (DERP), spring-like properties aim to replace the loss of musculature and soft tissues and optimise dynamic movement biomechanics, yet higher intact limb (IL) loading exists. It is unknown how amputees wearing a DERP will perform in start-stop movements and how altering the prosthetic stiffness will influence the performance and loading. This study assessed movement dynamics through comparisons in spatiotemporal, kinematic and kinetic variables and leg stiffness of intact, prosthetic and control limbs. The effect of prosthetic stiffness on movement dynamics was also determined. Eleven male unilateral transtibial amputees performed a start-stop task with one DERP set at two different stiffness - Prescribed and Stiffer. Eleven control participants performed the movement with the dominant limb. Kinematic and kinetic data were collected by a twelve-camera motion capture system synchronised with a Kistler force platform. Selected variables were compared between intact, prosthetic and control limbs, and against prosthetic stiffness using ANOVA and effect size. Pearson's Correlation was used to analyse relationship between leg stiffness and prosthetic deflection. Amputees showed a more horizontal approach to the bound during the start-stop movement, with lower horizontal velocities and a longer stance time on the IL compared to controls. In both stiffness conditions, the IL showed selected higher anteroposterior and vertical forces and impulses when compared to the controls. Leg stiffness was not significantly different between limbs as a result of the interplay between angle swept and magnitude of force, even with the change in prosthetic stiffness. A main effect for prosthetic stiffness was found only in higher impact forces of the prosthetic limb and more horizontal touchdown angles of the IL when using the prescribed DERP. In conclusion, amputees achieve the movement with a horizontal approach when compared to controls which

  16. Effects of forefoot bending stiffness of badminton shoes on agility, comfort perception and lower leg kinematics during typical badminton movements.

    Science.gov (United States)

    Park, Sang-Kyoon; Lam, Wing-Kai; Yoon, Sukhoon; Lee, Ki-Kwang; Ryu, Jiseon

    2017-09-01

    This study investigated whether an increase in the forefoot bending stiffness of a badminton shoe would positively affect agility, comfort and biomechanical variables during badminton-specific movements. Three shoe conditions with identical shoe upper and sole designs with different bending stiffness (Flexible, Regular and Stiff) were used. Elite male badminton players completed an agility test on a standard badminton court involving consecutive lunges in six directions, a comfort test performed by a pair of participants conducting a game-like practice trial and a biomechanics test involving a random assignment of consecutive right forward lunges. No significant differences were found in agility time and biomechanical variables among the three shoes. The players wearing the shoe with a flexible forefoot outsole demonstrated a decreased perception of comfort in the forefoot cushion compared to regular and stiffer conditions during the comfort test (p < 0.05). The results suggested that the modification of forefoot bending stiffness would influence individual perception of comfort but would not influence performance and lower extremity kinematics during the tested badminton-specific tasks. It was concluded that an optimisation of forefoot structure and materials in badminton shoes should consider the individual's perception to maximise footwear comfort in performance.

  17. Three Days of Intermittent Fasting: Repeated-Sprint Performance Decreased by Vertical-Stiffness Impairment.

    Science.gov (United States)

    Cherif, Anissa; Meeusen, Romain; Farooq, Abdulaziz; Ryu, Joong; Fenneni, Mohamed Amine; Nikolovski, Zoran; Elshafie, Sittana; Chamari, Karim; Roelands, Bart

    2017-03-01

    To examine the effects of 3 d of intermittent fasting (3d-IF: abstaining from eating/drinking from dawn to sunset) on physical performance and metabolic responses to repeated sprints (RSs). Twenty-one active males performed an RS test (2 sets: 5 × 5-s maximal sprints with 25 s of recovery between and 3 min of recovery between sets on an instrumented treadmill) in 2 conditions: counterbalanced fed/control session (CS) and fasting session (FS). Biomechanical and biochemical markers were assessed preexercise and postexercise. Significant main effects of IF were observed for sprints: maximal speed (P = .016), mean speed (P = .015), maximal power (P = .035), mean power (P = .049), vertical stiffness (P = .032), and vertical center-of-mass displacement (P = .047). Sprint speed and vertical stiffness decreased during the 1st (P = .003 and P = .005) and 2nd sprints (P = .046 and P = .048) of set 2, respectively. Postexercise insulin decreased in CS (P = .023) but not in FS (P = .230). Free-fatty-acid levels were higher in FS than in CS at preexercise (P intermittent fasting.

  18. Increased tea consumption is associated with decreased arterial stiffness in a Chinese population.

    Directory of Open Access Journals (Sweden)

    Chung-Hao Li

    Full Text Available BACKGROUND: Tea has attracted considerable attention for its potential cardioprotective effects. The primary chemical components of tea are thought to have a beneficial effect by reducing arterial stiffness. The objective of this study was to assess the association between tea consumption and brachial-ankle pulse wave velocity (baPWV in a relatively healthy Chinese population. METHODS: We enrolled 3,135 apparently healthy subjects from October 2006 to August 2009. Subjects taking medication for diabetes, hypertension, or hyperlipidemia, or with a history of cardiovascular disease, were excluded from the study. The subjects were categorized into three groups according to their tea-drinking habits: (1 none to low (n = 1615, defined as non-habitual tea drinkers, or drinking for 450 mL per day. Multiple logistic regression was used to determine whether different levels of consumption were independently associated with the highest quartile of baPWV values, defined as ≥1428.5 cm/s. RESULTS: Of the 3,135 subjects, 48.5% had drunk >150 mL of tea per day for at least 1 year. In multivariate regression analysis with adjustment for co-variables, including, age, sex, current smoking, alcohol use, habitual exercise, total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C ratio >5, obesity, newly diagnosed hypertension and diabetes, subjects with high tea consumption had a decreased risk of highest quartile of baPWV by 22% (odds ratio = 0.78, 95% confidence interval = 0.62-0.98, p = 0.032, while subjects with moderate tea consumption did not (p = 0.742, as compared subjects with none to low tea consumption. CONCLUSIONS: High, but not moderate, habitual tea consumption may decrease arterial stiffness.

  19. Region-dependent hamstrings activity in Nordic hamstring exercise and stiff-leg deadlift defined with high-density electromyography.

    Science.gov (United States)

    Hegyi, A; Péter, A; Finni, T; Cronin, N J

    2018-03-01

    Recent studies suggest region-specific metabolic activity in hamstring muscles during injury prevention exercises, but the neural representation of this phenomenon is unknown. The aim of this study was to examine whether regional differences are evident in the activity of biceps femoris long head (BFlh) and semitendinosus (ST) muscles during two common injury prevention exercises. Twelve male participants without a history of hamstring injury performed the Nordic hamstring exercise (NHE) and stiff-leg deadlift (SDL) while BFlh and ST activities were recorded with high-density electromyography (HD-EMG). Normalized activity was calculated from the distal, middle, and proximal regions in the eccentric phase of each exercise. In NHE, ST overall activity was substantially higher than in BFlh (d = 1.06 ± 0.45), compared to trivial differences between muscles in SDL (d = 0.19 ± 0.34). Regional differences were found in NHE for both muscles, with different proximal-distal patterns: The distal region showed the lowest activity level in ST (regional differences, d range = 0.55-1.41) but the highest activity level in BFlh (regional differences, d range = 0.38-1.25). In SDL, regional differences were smaller in both muscles (d range = 0.29-0.67 and 0.16-0.63 in ST and BFlh, respectively) than in NHE. The use of HD-EMG in hamstrings revealed heterogeneous hamstrings activity during typical injury prevention exercises. High-density EMG might be useful in future studies to provide a comprehensive overview of hamstring muscle activity in other exercises and high-injury risk tasks. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Inactivation of serum response factor contributes to decrease vascular muscular tone and arterial stiffness in mice.

    Science.gov (United States)

    Galmiche, Guillaume; Labat, Carlos; Mericskay, Mathias; Aissa, Karima Ait; Blanc, Jocelyne; Retailleau, Kevin; Bourhim, Mustapha; Coletti, Dario; Loufrani, Laurent; Gao-Li, Jacqueline; Feil, Robert; Challande, Pascal; Henrion, Daniel; Decaux, Jean-François; Regnault, Véronique; Lacolley, Patrick; Li, Zhenlin

    2013-03-29

    Vascular smooth muscle (SM) cell phenotypic modulation plays an important role in arterial stiffening associated with aging. Serum response factor (SRF) is a major transcription factor regulating SM genes involved in maintenance of the contractile state of vascular SM cells. We investigated whether SRF and its target genes regulate intrinsic SM tone and thereby arterial stiffness. The SRF gene was inactivated SM-specific knockout of SRF (SRF(SMKO)) specifically in vascular SM cells by injection of tamoxifen into adult transgenic mice. Fifteen days later, arterial pressure and carotid thickness were lower in SRF(SMKO) than in control mice. The carotid distensibility/pressure and elastic modulus/wall stress curves showed a greater arterial elasticity in SRF(SMKO) without modification in collagen/elastin ratio. In SRF(SMKO), vasodilation was decreased in aorta and carotid arteries, whereas a decrease in contractile response was found in mesenteric arteries. By contrast, in mice with inducible SRF overexpression, the in vitro contractile response was significantly increased in all arteries. Without endothelium, the contraction was reduced in SRF(SMKO) compared with control aortic rings owing to impairment of the NO pathway. Contractile components (SM-actin and myosin light chain), regulators of the contractile response (myosin light chain kinase, myosin phosphatase target subunit 1, and protein kinase C-potentiated myosin phosphatase inhibitor) and integrins were reduced in SRF(SMKO). SRF controls vasoconstriction in mesenteric arteries via vascular SM cell phenotypic modulation linked to changes in contractile protein gene expression. SRF-related decreases in vasomotor tone and cell-matrix attachment increase arterial elasticity in large arteries.

  1. Liver Stiffness Decreases Rapidly in Response to Successful Hepatitis C Treatment and Then Plateaus.

    Directory of Open Access Journals (Sweden)

    Sweta Chekuri

    Full Text Available To investigate the impact of a sustained virological response (SVR to hepatitis C virus (HCV treatment on liver stiffness (LS.LS, measured by transient elastography (FibroScan, demographic and laboratory data of patients treated with interferon (IFN-containing or IFN-free regimens who had an SVR24 (undetectable HCV viral load 24 weeks after the end of treatment were analyzed using two-tailed paired t-tests, Mann-Whitney Wilcoxon Signed-rank tests and linear regression. Two time intervals were investigated: pre-treatment to SVR24 and SVR24 to the end of follow-up. LS scores ≥ 12.5 kPa indicated LS-defined cirrhosis. A p-value below 0.05 was considered statistically significant.The median age of the patients (n = 100 was 60 years [IQR (interquartile range 54-64; 72% were male; 60% were Caucasian; and 42% had cirrhosis pre-treatment according to the FibroScan measurement. The median LS score dropped from 10.40 kPa (IQR: 7.25-18.60 pre-treatment to 7.60 kPa (IQR: 5.60-12.38 at SVR24, p <0.01. Among the 42 patients with LS-defined cirrhosis pre-treatment, 25 (60% of patients still had LS scores ≥ 12.5 kPa at SVR24, indicating the persistence of cirrhosis. The median change in LS was similar in patients receiving IFN-containing and IFN-free regimens: -1.95 kPa (IQR: -5.75 --0.38 versus -2.40 kPa (IQR: -7.70 --0.23, p = 0.74. Among 56 patients with a post-SVR24 LS measurement, the LS score changed by an additional -0.90 kPa (IQR: -2.98-0.5 during a median follow-up time of 1.17 (IQR: 0.88-1.63 years, which was not a statistically significant decrease (p = 0.99.LS decreased from pre-treatment to SVR24, but did not decrease significantly during additional follow-up. Earlier treatment may be needed to reduce the burden of liver disease.

  2. Hypoxia and loss of PHD2 inactivate stromal fibroblasts to decrease tumour stiffness and metastasis

    DEFF Research Database (Denmark)

    Madsen, Chris D; Pedersen, Jesper Thorhauge; Venning, Freja A

    2015-01-01

    , which can be prevented by simultaneous depletion of HIF-1α. Treatment with the PHD inhibitor DMOG in an orthotopic breast cancer model significantly decreases spontaneous metastases to the lungs and liver, associated with decreased tumour stiffness and fibroblast activation. PHD2 depletion in CAFs co......-injected with tumour cells similarly prevents CAF-induced metastasis to lungs and liver. Our data argue that reversion of CAFs towards a less active state is possible and could have important clinical implications....

  3. Exposure to wood smoke increases arterial stiffness and decreases heart rate variability in humans.

    Science.gov (United States)

    Unosson, Jon; Blomberg, Anders; Sandström, Thomas; Muala, Ala; Boman, Christoffer; Nyström, Robin; Westerholm, Roger; Mills, Nicholas L; Newby, David E; Langrish, Jeremy P; Bosson, Jenny A

    2013-06-06

    Emissions from biomass combustion are a major source of indoor and outdoor air pollution, and are estimated to cause millions of premature deaths worldwide annually. Whilst adverse respiratory health effects of biomass exposure are well established, less is known about its effects on the cardiovascular system. In this study we assessed the effect of exposure to wood smoke on heart rate, blood pressure, central arterial stiffness and heart rate variability in otherwise healthy persons. Fourteen healthy non-smoking subjects participated in a randomized, double-blind crossover study. Subjects were exposed to dilute wood smoke (mean particle concentration of 314±38 μg/m3) or filtered air for three hours during intermittent exercise. Heart rate, blood pressure, central arterial stiffness and heart rate variability were measured at baseline and for one hour post-exposure. Central arterial stiffness, measured as augmentation index, augmentation pressure and pulse wave velocity, was higher after wood smoke exposure as compared to filtered air (p smoke compared to filtered air. Acute exposure to wood smoke as a model of exposure to biomass combustion is associated with an immediate increase in central arterial stiffness and a simultaneous reduction in heart rate variability. As biomass is used for cooking and heating by a large fraction of the global population and is currently advocated as a sustainable alternative energy source, further studies are required to establish its likely impact on cardiovascular disease. ClinicalTrials.gov, NCT01488500.

  4. Robust and efficient walking with spring-like legs

    International Nuclear Information System (INIS)

    Rummel, J; Blum, Y; Seyfarth, A

    2010-01-01

    The development of bipedal walking robots is inspired by human walking. A way of implementing walking could be performed by mimicking human leg dynamics. A fundamental model, representing human leg dynamics during walking and running, is the bipedal spring-mass model which is the basis for this paper. The aim of this study is the identification of leg parameters leading to a compromise between robustness and energy efficiency in walking. It is found that, compared to asymmetric walking, symmetric walking with flatter angles of attack reveals such a compromise. With increasing leg stiffness, energy efficiency increases continuously. However, robustness is the maximum at moderate leg stiffness and decreases slightly with increasing stiffness. Hence, an adjustable leg compliance would be preferred, which is adaptable to the environment. If the ground is even, a high leg stiffness leads to energy efficient walking. However, if external perturbations are expected, e.g. when the robot walks on uneven terrain, the leg should be softer and the angle of attack flatter. In the case of underactuated robots with constant physical springs, the leg stiffness should be larger than k-tilde = 14 in order to use the most robust gait. Soft legs, however, lack in both robustness and efficiency.

  5. Glucose Uptake Is Decreased in Affected Lower Leg Muscles of Hemiparetic Persons during Level Walking.

    Science.gov (United States)

    Oi, Naoyuki; Itoh, Masatoshi; Tobimatsu, Yoshiko; Konno, Shinichi; Kikuchi, Shinichi; Iwaya, Tsutomu

    2015-12-01

    Stroke patients suffer from gait disturbance due to altered leg muscle actions. Many kinesiological studies have investigated muscle actions, but the metabolic activity of muscles in stroke patients remains to be investigated. We therefore evaluated energy consumption in lower extremity muscles during level walking in hemiparetic individuals. Glucose uptake was measured by positron emission tomography (PET) using (18)F-fluorodeoxyglucose ((18)F-FDG) in eight hemiparetic (mean age: 56 years) and 11 healthy (mean age: 26 years) participants. Standardized uptake ratio (SUR) was computed in each muscle to express the (18)F-FDG-uptake level. SUR was compared across gluteal, thigh, and lower leg muscles and across individual muscles within each muscle group. For each muscle, SUR was compared among the paretic limb of hemiparetic participants, the non-paretic limb of hemiparetic participants, and the right limb of healthy participants. In paretic limbs, mean SUR did not differ between the three muscle groups, or between individual muscles within each muscle group. SURs of paretic lower leg muscles and gluteus minimus muscle were significantly smaller than those of non-paretic limb and healthy participants (p limb of hemiparetic participants, SUR of the lower leg muscles was larger than that of the thigh muscles (p muscles were larger in the non-paretic limb of hemiparetic participants, compared to the right limb of healthy participants (p lower extremity muscles during level walking in hemiparetic individuals.

  6. Reduced mechanical load decreases the density, stiffness, and strength of cancellous bone of the mandibular condyle.

    NARCIS (Netherlands)

    Giesen, E.B.W.; Ding, M.; Dalstra, M.; Eijden, T.M. van

    2003-01-01

    OBJECTIVE: To investigate the influence of decreased mechanical loading on the density and mechanical properties of the cancellous bone of the human mandibular condyle. DESIGN: Destructive compressive mechanical tests were performed on cancellous bone specimens.Background. Reduced masticatory

  7. Decreased nuclear stiffness via FAK-ERK1/2 signaling is necessary for osteopontin-promoted migration of bone marrow-derived mesenchymal stem cells

    International Nuclear Information System (INIS)

    Liu, Lingling; Luo, Qing; Sun, Jinghui; Wang, Aoli; Shi, Yisong; Ju, Yang; Morita, Yasuyuki; Song, Guanbin

    2017-01-01

    Migration of bone marrow-derived mesenchymal stem cells (BMSCs) plays an important role in many physiological and pathological settings, including wound healing. During the migration of BMSCs through interstitial tissues, the movement of the nucleus must be coordinated with the cytoskeletal dynamics, which in turn affects the cell migration efficiency. Our previous study indicated that osteopontin (OPN) significantly promotes the migration of rat BMSCs. However, the nuclear behaviors and involved molecular mechanisms in OPN-mediated BMSC migration are largely unclear. In the present study, using an atomic force microscope (AFM), we found that OPN could decrease the nuclear stiffness of BMSCs and reduce the expression of lamin A/C, which is the main determinant of nuclear stiffness. Increased lamin A/C expression attenuates BMSC migration by increasing nuclear stiffness. Decreased lamin A/C expression promotes BMSC migration by decreasing nuclear stiffness. Furthermore, OPN promotes BMSC migration by diminishing lamin A/C expression and decreasing nuclear stiffness via the FAK-ERK1/2 signaling pathway. This study provides strong evidence for the role of nuclear mechanics in BMSC migration as well as new insight into the molecular mechanisms of OPN-promoted BMSC migration. - Highlights: • OPN promotes BMSC migration by decreasing nuclear stiffness. • Lamin A/C knockdown decreases, while its overexpression enhances, the nuclear stiffness of BMSCs. • Lamin A/C overexpression and downregulation affect the migration of BMSCs. • OPN diminishes lamin A/C expression and decreases nuclear stiffness through the activation of the FAK-ERK1/2 signaling pathway. • OPN promotes BMSC migration via the FAK-ERK1/2 signaling pathway.

  8. Decreased nuclear stiffness via FAK-ERK1/2 signaling is necessary for osteopontin-promoted migration of bone marrow-derived mesenchymal stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lingling, E-mail: liulingling2012@163.com [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Luo, Qing, E-mail: qing.luo@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Sun, Jinghui, E-mail: sunjhemail@163.com [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Wang, Aoli, E-mail: leaf13332@163.com [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Shi, Yisong, E-mail: shiyis@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Ju, Yang, E-mail: ju@mech.nagoya-u.ac.jp [Department of Mechanical Science and Engineering, Nagoya University, Nagoya 464-8603 (Japan); Morita, Yasuyuki, E-mail: morita@mech.nagoya-u.ac.jp [Department of Mechanical Science and Engineering, Nagoya University, Nagoya 464-8603 (Japan); Song, Guanbin, E-mail: song@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China)

    2017-06-15

    Migration of bone marrow-derived mesenchymal stem cells (BMSCs) plays an important role in many physiological and pathological settings, including wound healing. During the migration of BMSCs through interstitial tissues, the movement of the nucleus must be coordinated with the cytoskeletal dynamics, which in turn affects the cell migration efficiency. Our previous study indicated that osteopontin (OPN) significantly promotes the migration of rat BMSCs. However, the nuclear behaviors and involved molecular mechanisms in OPN-mediated BMSC migration are largely unclear. In the present study, using an atomic force microscope (AFM), we found that OPN could decrease the nuclear stiffness of BMSCs and reduce the expression of lamin A/C, which is the main determinant of nuclear stiffness. Increased lamin A/C expression attenuates BMSC migration by increasing nuclear stiffness. Decreased lamin A/C expression promotes BMSC migration by decreasing nuclear stiffness. Furthermore, OPN promotes BMSC migration by diminishing lamin A/C expression and decreasing nuclear stiffness via the FAK-ERK1/2 signaling pathway. This study provides strong evidence for the role of nuclear mechanics in BMSC migration as well as new insight into the molecular mechanisms of OPN-promoted BMSC migration. - Highlights: • OPN promotes BMSC migration by decreasing nuclear stiffness. • Lamin A/C knockdown decreases, while its overexpression enhances, the nuclear stiffness of BMSCs. • Lamin A/C overexpression and downregulation affect the migration of BMSCs. • OPN diminishes lamin A/C expression and decreases nuclear stiffness through the activation of the FAK-ERK1/2 signaling pathway. • OPN promotes BMSC migration via the FAK-ERK1/2 signaling pathway.

  9. Short-term attention and verbal fluency is decreased in restless legs syndrome patients.

    Science.gov (United States)

    Fulda, Stephany; Beitinger, Marie E; Reppermund, Simone; Winkelmann, Juliane; Wetter, Thomas C

    2010-11-15

    Restless legs syndrome (RLS) is a frequent sleep-related movement disorder with disturbed sleep and quality of life. RLS patients complain about increased daytime sleepiness, but there are only few and inconsistent reports about cognitive functioning in this group. We compared cognitive performance of 23 unmedicated RLS patients to that of 23 healthy controls matched individually for age, gender, and educational level. Cognitive tasks were chosen to assess short-term attention, working memory, learning and memory, verbal fluency, and executive functioning. RLS patients performed worse than controls in the area of attention and verbal fluency, and performance in these tasks was associated with RLS severity, sleep quality, depression scores, and memory. There was no difference for working memory, memory, learning, cognitive flexibility, and abstract reasoning. We conclude that there is evidence for deficits in short-term attention and verbal fluency in RLS patients. © 2010 Movement Disorder Society.

  10. Decreased nuclear stiffness via FAK-ERK1/2 signaling is necessary for osteopontin-promoted migration of bone marrow-derived mesenchymal stem cells.

    Science.gov (United States)

    Liu, Lingling; Luo, Qing; Sun, Jinghui; Wang, Aoli; Shi, Yisong; Ju, Yang; Morita, Yasuyuki; Song, Guanbin

    2017-06-15

    Migration of bone marrow-derived mesenchymal stem cells (BMSCs) plays an important role in many physiological and pathological settings, including wound healing. During the migration of BMSCs through interstitial tissues, the movement of the nucleus must be coordinated with the cytoskeletal dynamics, which in turn affects the cell migration efficiency. Our previous study indicated that osteopontin (OPN) significantly promotes the migration of rat BMSCs. However, the nuclear behaviors and involved molecular mechanisms in OPN-mediated BMSC migration are largely unclear. In the present study, using an atomic force microscope (AFM), we found that OPN could decrease the nuclear stiffness of BMSCs and reduce the expression of lamin A/C, which is the main determinant of nuclear stiffness. Increased lamin A/C expression attenuates BMSC migration by increasing nuclear stiffness. Decreased lamin A/C expression promotes BMSC migration by decreasing nuclear stiffness. Furthermore, OPN promotes BMSC migration by diminishing lamin A/C expression and decreasing nuclear stiffness via the FAK-ERK1/2 signaling pathway. This study provides strong evidence for the role of nuclear mechanics in BMSC migration as well as new insight into the molecular mechanisms of OPN-promoted BMSC migration. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Oral ADSORBENT AST-120 decreases carotid intima-media thickness and arterial stiffness in patients with chronic renal failure.

    Science.gov (United States)

    Nakamura, Tsukasa; Kawagoe, Yasuhiro; Matsuda, Takaharu; Ueda, Yoshihiko; Shimada, Noriaki; Ebihara, Isao; Koide, Hikaru

    2004-01-01

    Intima media thickness (IMT) and stiffness of the carotid arteries is related to coronary artery disease, and chronic renal failure patients are at high risk for such diseases. An oral adsorbent, AST-120 (Kremezin; Kureha Chemical Industry, Tokyo, Japan), can delay the progression of chronic renal failure in undialyzed uremic patients. The aim of the present study was to determine whether AST-120 affects carotid artery IMT and pulse wave velocity (PWV) in patients with chronic renal failure not undergoing dialysis. Fifty patients with non-diabetic chronic renal failure were randomly divided into two groups: 30 patients (18 men and 12 women; mean age 53.5 years; mean serum creatinine 3.2 mg/dl) who were given AST-120 (6.0 g/day) and 20 patients (12 men and 8 women; mean age 52.0 years; mean serum creatinine 3.5 mg/dl) who were not given AST-120. Thirty healthy age-matched subjects (18 men and 12 women; mean age 51.5 years; mean serum creatinine 0.9 mg/dl) were also included. The treatment period was 24 months. IMT and arterial stiffness were measured before and after treatment. The slope of the reciprocal serum creatinine concentration over time became significantly less steep in the AST-120 group than in the non-AST-120 group (p < 0.001). Before treatment, carotid artery IMT differed little between the AST-120 group (0.90 +/- 0.22 mm) and the non-AST-120 group (0.88 +/- 0.20 mm). IMT in these two groups was significantly greater than IMT in the control group (0.64 +/- 0.14 mm) (p < 0.01). Carotid IMT in the AST-120 group decreased slightly but not significantly to 0.84 +/- 0.20 mm after 12 months and then significantly after 24 months to 0.78 +/- 0.18 mm (p < 0.05). Carotid IMT in the non-AST group showed little change throughout the experimental period. PWV differed little between the AST-120 group (1,980 +/- 330 cm/s) and the non-AST group (1,940 +/- 360 cm/s) before treatment. PWV values in these two groups were significantly greater than PWV in the control

  12. Individuals with chronic ankle instability exhibit decreased postural sway while kicking in a single-leg stance.

    Science.gov (United States)

    dos Santos, Marcio José; Gorges, Ana Luiza; Rios, Jaqueline Lourdes

    2014-01-01

    Individuals with chronic ankle instability (CAI) usually experience deficits in balance control, which increase displacement in the body's center of pressure (COP) when they balance on a single leg. Little is known, however, about whether or not these individuals use the strategies of postural adjustment properly, especially during functional tasks that may predispose them to ankle sprain. The aim of this study was to investigate anticipatory (APA) and compensatory (CPA) postural adjustments in individuals with and without CAI as they kick a ball while standing in a single-leg stance with their ankle in neutral and supinated positions. COP displacements were calculated and their magnitudes (range) analyzed during APA and CPA intervals and over the duration of the whole task, represented by the COP area of sway and mean velocity. The CAI group exhibited a significant decrease in CPA and area of sway over the whole task, relative to controls. These results suggest that the decreased balance sway could be caused by the need for further stabilization of the ankle in more unstable postures to prevent recurrent sprain. Our findings could help clinicians to better understand the strategies of postural adjustments in individuals with CAI, and may assist and motivate new investigations into balance control interventions in such individuals, as well as proactively address recurrent ankle sprain conditions. Published by Elsevier B.V.

  13. Elevated gastrocnemius forces compensate for decreased hamstrings forces during the weight-acceptance phase of single-leg jump landing: implications for anterior cruciate ligament injury risk.

    Science.gov (United States)

    Morgan, Kristin D; Donnelly, Cyril J; Reinbolt, Jeffrey A

    2014-10-17

    Approximately 320,000 anterior cruciate ligament (ACL) injuries in the United States each year are non-contact injuries, with many occurring during a single-leg jump landing. To reduce ACL injury risk, one option is to improve muscle strength and/or the activation of muscles crossing the knee under elevated external loading. This study's purpose was to characterize the relative force production of the muscles supporting the knee during the weight-acceptance (WA) phase of single-leg jump landing and investigate the gastrocnemii forces compared to the hamstrings forces. Amateur male Western Australian Rules Football players completed a single-leg jump landing protocol and six participants were randomly chosen for further modeling and simulation. A three-dimensional, 14-segment, 37 degree-of-freedom, 92 muscle-tendon actuated model was created for each participant in OpenSim. Computed muscle control was used to generate 12 muscle-driven simulations, 2 trials per participant, of the WA phase of single-leg jump landing. A one-way ANOVA and Tukey post-hoc analysis showed both the quadriceps and gastrocnemii muscle force estimates were significantly greater than the hamstrings (p<0.001). Elevated gastrocnemii forces corresponded with increased joint compression and lower ACL forces. The elevated quadriceps and gastrocnemii forces during landing may represent a generalized muscle strategy to increase knee joint stiffness, protecting the knee and ACL from external knee loading and injury risk. These results contribute to our understanding of how muscle's function during single-leg jump landing and should serve as the foundation for novel muscle-targeted training intervention programs aimed to reduce ACL injuries in sport. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Decreased hematocrit-to-viscosity ratio and increased lactate dehydrogenase level in patients with sickle cell anemia and recurrent leg ulcers.

    Directory of Open Access Journals (Sweden)

    Philippe Connes

    Full Text Available Leg ulcer is a disabling complication in patients with sickle cell anemia (SCA but the exact pathophysiological mechanisms are unknown. The aim of this study was to identify the hematological and hemorheological alterations associated with recurrent leg ulcers. Sixty-two SCA patients who never experienced leg ulcers (ULC- and 13 SCA patients with a positive history of recurrent leg ulcers (ULC+--with no leg ulcers at the time of the study--were recruited. All patients were in steady state condition. Blood was sampled to perform hematological, biochemical (hemolytic markers and hemorheological analyses (blood viscosity, red blood cell deformability and aggregation properties. The hematocrit-to-viscosity ratio (HVR, which reflects the red blood cell oxygen transport efficiency, was calculated for each subject. Patients from the ULC+ group were older than patients from the ULC- group. Anemia (red blood cell count, hematocrit and hemoglobin levels was more pronounced in the ULC+ group. Lactate dehydrogenase level was higher in the ULC+ group than in the ULC- group. Neither blood viscosity, nor RBC aggregation properties differed between the two groups. HVR was lower and RBC deformability tended to be reduced in the ULC+ group. Our study confirmed increased hemolytic rate and anemia in SCA patients with leg ulcers recurrence. Furthermore, our data suggest that although systemic blood viscosity is not a major factor involved in the pathophysiology of this complication, decreased red blood cell oxygen transport efficiency (i.e., low hematocrit/viscosity ratio may play a role.

  15. Reduced prosthetic stiffness lowers the metabolic cost of running for athletes with bilateral transtibial amputations.

    Science.gov (United States)

    Beck, Owen N; Taboga, Paolo; Grabowski, Alena M

    2017-04-01

    Inspired by the springlike action of biological legs, running-specific prostheses are designed to enable athletes with lower-limb amputations to run. However, manufacturer's recommendations for prosthetic stiffness and height may not optimize running performance. Therefore, we investigated the effects of using different prosthetic configurations on the metabolic cost and biomechanics of running. Five athletes with bilateral transtibial amputations each performed 15 trials on a force-measuring treadmill at 2.5 or 3.0 m/s. Athletes ran using each of 3 different prosthetic models (Freedom Innovations Catapult FX6, Össur Flex-Run, and Ottobock 1E90 Sprinter) with 5 combinations of stiffness categories (manufacturer's recommended and ± 1) and heights (International Paralympic Committee's maximum competition height and ± 2 cm) while we measured metabolic rates and ground reaction forces. Overall, prosthetic stiffness [fixed effect (β) = 0.036; P = 0.008] but not height ( P ≥ 0.089) affected the net metabolic cost of transport; less stiff prostheses reduced metabolic cost. While controlling for prosthetic stiffness (in kilonewtons per meter), using the Flex-Run (β = -0.139; P = 0.044) and 1E90 Sprinter prostheses (β = -0.176; P = 0.009) reduced net metabolic costs by 4.3-4.9% compared with using the Catapult prostheses. The metabolic cost of running improved when athletes used prosthetic configurations that decreased peak horizontal braking ground reaction forces (β = 2.786; P = 0.001), stride frequencies (β = 0.911; P < 0.001), and leg stiffness values (β = 0.053; P = 0.009). Remarkably, athletes did not maintain overall leg stiffness across prosthetic stiffness conditions. Rather, the in-series prosthetic stiffness governed overall leg stiffness. The metabolic cost of running in athletes with bilateral transtibial amputations is influenced by prosthetic model and stiffness but not height. NEW & NOTEWORTHY We measured the

  16. Are substrate use during exercise and mitochondrial respiratory capacity decreased in arm and leg muscle in type 2 diabetes?

    DEFF Research Database (Denmark)

    Larsen, Steen; Ara, I; Rabøl, R

    2009-01-01

    AIM/HYPOTHESIS: The aim of the study was to investigate mitochondrial function, fibre type distribution and substrate oxidation in arm and leg muscle during exercise in patients with type 2 diabetes and in obese and lean controls. METHODS: Indirect calorimetry was used to calculate fat and carboh...

  17. Fixed-Angle, Posteriorly Connected Anterior Cage Reconstruction Improves Stiffness and Decreases Cancellous Subsidence in a Spondylectomy Model.

    Science.gov (United States)

    Colman, Matthew W; Guss, Andrew; Bachus, Kent N; Spiker, W Ryan; Lawrence, Brandon D; Brodke, Darrel S

    2016-05-01

    An idealized biomechanical model. The aim of this study was to evaluate the biomechanical properties of a construct designed to minimize intervertebral cage subsidence and maximize stiffness. Reconstruction after vertebral resection typically involves posterior segmental fixation and anterior interbody support. However, poor bone density, adjuvant radiation, or the oncologic need for endplate resection make interbody device subsidence and resultant instrumentation failure a significant concern. An idealized thoracolumbar spondylectomy reconstruction model was constructed using titanium segmental instrumentation and Delrin plastic. In vivo mechanical stress was simulated on a custom multi-axis spine simulator. Rigid body position in space was measured using an optical motion-capture system. Cancellous subsidence was modeled using a 1 cm thick wafer of number 3 closed-cell Sawbones foam at one endplate. Ten foam specimens were tested in a control state consisting of posterior segmental fixation with a free interbody cage. Ten additional foam specimens were tested in the test state, with the Delrin interbody cage "connected" to the posterior rods using two additional pedicle screws placed into the cage. Foam indentation was quantified using a precision digital surface-mapping device, and subsidence volume calculated using geometric integration. The control group exhibited significantly greater foam indentation after cycling, with a mean subsidence volume of 1906 mm [95% confidence interval (95% CI) 1810-2001] than the connected cage group subsidence volume of 977 mm (95% CI 928-1026 mm; P subsidence compared with a traditional unconnected cage. N/A.

  18. Venogram - leg

    Science.gov (United States)

    Phlebogram - leg; Venography - leg; Angiogram - leg ... into a vein in the foot of the leg being looked at. An intravenous (IV) line is ... vein. A tourniquet may be placed on your leg so the dye flows into the deeper veins. ...

  19. Leg elevation decreases the incidence of post-spinal hypotension in cesarean section: a randomized controlled trial.

    Science.gov (United States)

    Hasanin, Ahmed; Aiyad, Ahmed; Elsakka, Ahmed; Kamel, Atef; Fouad, Reham; Osman, Mohamed; Mokhtar, Ali; Refaat, Sherin; Hassabelnaby, Yasmin

    2017-04-24

    Maternal hypotension is a common complication after spinal anesthesia for cesarean section (CS). In this study we investigated the role of leg elevation (LE) as a method for prevention of post-spinal hypotension (PSH) for cesarean section. One hundred and fifty full term parturients scheduled for CS were included in the study. Patients were randomized into two groups: Group LE (leg elevation group, n = 75) and group C (Control group, n = 75). Spinal block was performed in sitting position after administration of 10 mL/Kg Ringer's lactate as fluid preload. After successful intrathecal injection of local anesthetic, Patients were positioned in the supine position. Leg elevation was performed for LE group directly after spinal anesthesia and maintained till skin incision. Intraoperative hemodynamic parameters (Arterial blood pressure and heart rate), intra-operative ephedrine consumption, incidence of PSH, and incidence of nausea and vomiting were reported. LE group showed lower incidence of PSH (34.7% Vs 58.7%, P = 0.005) compared to the control group. Arterial blood pressure was higher in the LE group compared to the control group in the first two readings after spinal block. Other readings showed comparable arterial blood pressure and heart rate values between both study groups; however, LE showed less ephedrine consumption (4.9 ± 7.8 mg Vs 10 ± 11 mg, P = 0.001). LE performed immediately after spinal block reduced the incidence of PSH in parturients undergoing CS. The study was registered at Pan African Clinical Trials Registry system on 5/10/2015 with trial number PACTR201510001295348 .

  20. Lower Extremity Stiffness Changes following Concussion in Collegiate Football Players

    Science.gov (United States)

    DuBose, Dominique F.; Herman, Daniel C.; Jones, Debi L.; Tillman, Susan M.; Clugston, James R.; Pass, Anthony; Hernandez, Jorge A.; Vasilopoulos, Terrie; Horodyski, MaryBeth; Chmielewski, Terese L.

    2016-01-01

    Purpose Recent research indicates that a concussion increases risk of musculoskeletal injury. Neuromuscular changes following concussion might contribute to the increased risk of injury. Many studies have examined gait post-concussion, but few studies have examined more demanding tasks. This study compared changes in stiffness across the lower extremity, a measure of neuromuscular function, during a jump-landing task in athletes with a concussion (CONC) to uninjured athletes (UNINJ). Methods Division I football players (13 CONC, 26 UNINJ) were tested pre- and post-season. A motion-capture system recorded subjects jumping on one limb from a 25.4 cm step onto a force plate. Hip, knee, and ankle joint stiffness were calculated from initial contact to peak joint flexion using the regression line slopes of the joint moment versus joint angle plots. Leg stiffness was (peak vertical ground reaction force (PVGRF)/lower extremity vertical displacement) from initial contact to PVGRF. All stiffness values were normalized to bodyweight. Values from both limbs were averaged. General linear models compared group (CONC, UNINJ) differences in the changes of pre- and post-season stiffness values. Results Average time from concussion to post-season testing was 49.9 days. The CONC group showed an increase in hip stiffness (p=0.03), a decrease in knee (p=0.03) and leg stiffness (p=0.03), but no change in ankle stiffness (p=0.65) from pre- to post-season. Conclusion Lower extremity stiffness is altered following concussion, which could contribute to an increased risk of lower extremity injury. These data provide further evidence of altered neuromuscular function after concussion. PMID:27501359

  1. Lower Extremity Stiffness Changes after Concussion in Collegiate Football Players.

    Science.gov (United States)

    Dubose, Dominique F; Herman, Daniel C; Jones, Deborah L; Tillman, Susan M; Clugston, James R; Pass, Anthony; Hernandez, Jorge A; Vasilopoulos, Terrie; Horodyski, Marybeth; Chmielewski, Terese L

    2017-01-01

    Recent research indicates that a concussion increases the risk of musculoskeletal injury. Neuromuscular changes after concussion might contribute to the increased risk of injury. Many studies have examined gait postconcussion, but few studies have examined more demanding tasks. This study compared changes in stiffness across the lower extremity, a measure of neuromuscular function, during a jump-landing task in athletes with a concussion (CONC) to uninjured athletes (UNINJ). Division I football players (13 CONC and 26 UNINJ) were tested pre- and postseason. A motion capture system recorded subjects jumping on one limb from a 25.4-cm step onto a force plate. Hip, knee, and ankle joint stiffness were calculated from initial contact to peak joint flexion using the regression line slopes of the joint moment versus the joint angle plots. Leg stiffness was (peak vertical ground reaction force [PVGRF]/lower extremity vertical displacement) from initial contact to peak vertical ground reaction force. All stiffness values were normalized to body weight. Values from both limbs were averaged. General linear models compared group (CONC, UNINJ) differences in the changes of pre- and postseason stiffness values. Average time from concussion to postseason testing was 49.9 d. The CONC group showed an increase in hip stiffness (P = 0.03), a decrease in knee (P = 0.03) and leg stiffness (P = 0.03), but no change in ankle stiffness (P = 0.65) from pre- to postseason. Lower extremity stiffness is altered after concussion, which could contribute to an increased risk of lower extremity injury. These data provide further evidence of altered neuromuscular function after concussion.

  2. Knee stiffness and viscosity: New implementation and perspectives in prosthesis development

    Directory of Open Access Journals (Sweden)

    Klemen Bohinc

    2017-05-01

    Full Text Available The pendulum test is a method applied to measure passive resistance of the knee. A new and simple pendulum test with instrumentation based on infrared camera was used to evaluate knee stiffness and viscosity on a female human cadaver. The stiffness and viscosity were calculated based on the kinetic data. During the measurements, the periarticular and intraarticular soft tissue of the knee was gradually removed to determine the stiffness and viscosity as a function of the tissue removal rate. The measurements showed that the removal of tissue around the joint reduces the damping of leg oscillation, and therefore decreases the stiffness and viscosity. The contribution to knee joint damping was 10% for the skin, 20% for ligaments, and 40% for muscles and tendons. Tissue removal has a very large impact on the knee stiffness and viscosity.

  3. Knee stiffness and viscosity: New implementation and perspectives in prosthesis development.

    Science.gov (United States)

    Bohinc, Klemen; Vantur, Nejc; Torkar, Drago; Lampe, Tomaž; Hribernik, Marija; Jakovljević, Miroljub

    2017-05-20

    The pendulum test is a method applied to measure passive resistance of the knee. A new and simple pendulum test with instrumentation based on infrared camera was used to evaluate knee stiffness and viscosity on a female human cadaver. The stiffness and viscosity were calculated based on the kinetic data. During the measurements, the periarticular and intraarticular soft tissue of the knee was gradually removed to determine the stiffness and viscosity as a function of the tissue removal rate. The measurements showed that the removal of tissue around the joint reduces the damping of leg oscillation, and therefore decreases the stiffness and viscosity. The contribution to knee joint damping was 10% for the skin, 20% for ligaments, and 40% for muscles and tendons. Tissue removal has a very large impact on the knee stiffness and viscosity.

  4. The Effect of Fatigue on the Stiffness Changes in Legs, Ankle and Knee Joints in Lower Limb During a Thirty-Second Continuous Vertical Jump Test in Female Volleyball Players

    Directory of Open Access Journals (Sweden)

    zahra Hatami Joushghan

    2015-12-01

    Conclusion: As the height of the jump and stiffness changes in lower body parts is an important factor in fields such as volleyball, coaches need to pay due attention to stiffness changes and improve their training techniques.

  5. Two weeks of one-leg immobilization decreases skeletal muscle respiratory capacity equally in young and elderly men

    DEFF Research Database (Denmark)

    Gram, Martin; Vigelsø Hansen, Andreas; Yokota, Takashi

    2014-01-01

    Physical inactivity affects human skeletal muscle mitochondrial oxidative capacity but the influence of aging combined with physical inactivity is not known. This study investigates the effect of two weeks of immobilization followed by six weeks of supervised cycle training on muscle oxidative...... capacity in 17 young (23±1years) and 15 elderly (68±1years) healthy men. We applied high-resolution respirometry in permeabilized fibers from muscle biopsies at inclusion after immobilization and training. Furthermore, protein content of mitochondrial complexes I-V, mitochondrial heat shock protein 70 (mt...... of VDAC, mtHSP70 and complexes I, II, IV and V decreased with immobilization and increased with retraining. Moreover, there was no overall difference in the response between the groups. When the intrinsic mitochondrial capacity was evaluated by normalizing respiration to citrate synthase activity...

  6. Stiffness Analysis of Above Knee Prosthesis

    OpenAIRE

    Ege, Mücahit; Küçük, Serdar

    2016-01-01

    While a healthy human walks, his or her legs mutually perform good repeatabilitywith high accuracy. This provides an esthetical movement and balance. Peoplewith above knee prosthesis want to perform walking as esthetical as a healthyhuman. Therefore, to achieve a healthy walking, the above knee prosthesis mustprovide a good stiffness performance. Especially stiffness values are requiredwhen adding a second axis movement to the ankle for eversion and inversion. Inthis paper, stiffness analysis...

  7. Prosthetic model, but not stiffness or height, affects the metabolic cost of running for athletes with unilateral transtibial amputations.

    Science.gov (United States)

    Beck, Owen N; Taboga, Paolo; Grabowski, Alena M

    2017-07-01

    Running-specific prostheses enable athletes with lower limb amputations to run by emulating the spring-like function of biological legs. Current prosthetic stiffness and height recommendations aim to mitigate kinematic asymmetries for athletes with unilateral transtibial amputations. However, it is unclear how different prosthetic configurations influence the biomechanics and metabolic cost of running. Consequently, we investigated how prosthetic model, stiffness, and height affect the biomechanics and metabolic cost of running. Ten athletes with unilateral transtibial amputations each performed 15 running trials at 2.5 or 3.0 m/s while we measured ground reaction forces and metabolic rates. Athletes ran using three different prosthetic models with five different stiffness category and height combinations per model. Use of an Ottobock 1E90 Sprinter prosthesis reduced metabolic cost by 4.3 and 3.4% compared with use of Freedom Innovations Catapult [fixed effect (β) = -0.177; P < 0.001] and Össur Flex-Run (β = -0.139; P = 0.002) prostheses, respectively. Neither prosthetic stiffness ( P ≥ 0.180) nor height ( P = 0.062) affected the metabolic cost of running. The metabolic cost of running was related to lower peak (β = 0.649; P = 0.001) and stance average (β = 0.772; P = 0.018) vertical ground reaction forces, prolonged ground contact times (β = -4.349; P = 0.012), and decreased leg stiffness (β = 0.071; P < 0.001) averaged from both legs. Metabolic cost was reduced with more symmetric peak vertical ground reaction forces (β = 0.007; P = 0.003) but was unrelated to stride kinematic symmetry ( P ≥ 0.636). Therefore, prosthetic recommendations based on symmetric stride kinematics do not necessarily minimize the metabolic cost of running. Instead, an optimal prosthetic model, which improves overall biomechanics, minimizes the metabolic cost of running for athletes with unilateral transtibial amputations. NEW & NOTEWORTHY The metabolic cost of running for

  8. Interaction of the human body and surfaces of different stiffness during drop jumps.

    Science.gov (United States)

    Arampatzis, Adamantios; Stafilidis, Savvas; Morey-Klapsing, Gaspar; Brüggemann, Gert-peter

    2004-03-01

    The purpose of this study was to examine two hypotheses: (a) the stiffness of the surface influences the leg stiffness of the subjects during drop jumps, and (b) drop jumping performance (jumping height and energy rates of the subject's center of mass during the contact phase) increases when decreasing surface stiffness due to a greater energy storage capacity of the surface for a given acting force. Ten female subjects performed a series of drop jumps from 40-cm height onto two sprung surfaces with different stiffness. Those trials of each subject displaying the maximal mechanical power during the upward phase were analyzed. The ground reaction forces were measured using a force plate. Sagittal kinematics of the subject's body positions and the deformation of the surface were recorded using two high-speed video cameras. On the soft surface, the jumping height and the energy rates of the subjects during the contact phase were greater than on the hard one. The energy delivered by the subjects during the upward phase, the leg and joint stiffness, as well as the range of motion of the subjects remained unchanged for both surfaces. The absolute energy loss is lower for the hard surface, but the jumping performance is greater for the soft one. The reason is a higher ratio of positive to negative mechanical work done by the subjects during the contact phase. The adjustment of the subjects to different surfaces is not only dependent on the stiffness of the surface but also on the intensity of the movement.

  9. Massage induces an immediate, albeit short-term, reduction in muscle stiffness.

    Science.gov (United States)

    Eriksson Crommert, M; Lacourpaille, L; Heales, L J; Tucker, K; Hug, F

    2015-10-01

    Using ultrasound shear wave elastography, the aims of this study were: (a) to evaluate the effect of massage on stiffness of the medial gastrocnemius (MG) muscle and (b) to determine whether this effect (if any) persists over a short period of rest. A 7-min massage protocol was performed unilaterally on MG in 18 healthy volunteers. Measurements of muscle shear elastic modulus (stiffness) were performed bilaterally (control and massaged leg) in a moderately stretched position at three time points: before massage (baseline), directly after massage (follow-up 1), and following 3 min of rest (follow-up 2). Directly after massage, participants rated pain experienced during the massage. MG shear elastic modulus of the massaged leg decreased significantly at follow-up 1 (-5.2 ± 8.8%, P = 0.019, d = -0.66). There was no difference between follow-up 2 and baseline for the massaged leg (P = 0.83) indicating that muscle stiffness returned to baseline values. Shear elastic modulus was not different between time points in the control leg. There was no association between perceived pain during the massage and stiffness reduction (r = 0.035; P = 0.89). This is the first study to provide evidence that massage reduces muscle stiffness. However, this effect is short lived and returns to baseline values quickly after cessation of the massage. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Arterial stiffness

    Directory of Open Access Journals (Sweden)

    Ursula Quinn

    2012-09-01

    Full Text Available Measurements of biomechanical properties of arteries have become an important surrogate outcome used in epidemiological and interventional cardiovascular research. Structural and functional differences of vessels in the arterial tree result in a dampening of pulsatility and smoothing of blood flow as it progresses to capillary level. A loss of arterial elastic properties results a range of linked pathophysiological changes within the circulation including increased pulse pressure, left ventricular hypertrophy, subendocardial ischaemia, vessel endothelial dysfunction and cardiac fibrosis. With increased arterial stiffness, the microvasculature of brain and kidneys are exposed to wider pressure fluctuations and may lead to increased risk of stroke and renal failure. Stiffening of the aorta, as measured by the gold-standard technique of aortic Pulse Wave Velocity (aPWV, is independently associated with adverse cardiovascular outcomes across many different patient groups and in the general population. Therefore, use of aPWV has been proposed for early detection of vascular damage and individual cardiovascular risk evaluation and it seems certain that measurement of arterial stiffness will become increasingly important in future clinical care. In this review we will consider some of the pathophysiological processes that result from arterial stiffening, how it is measured and factors that may drive it as well as potential avenues for therapy. In the face of an ageing population where mortality from atheromatous cardiovascular disease is falling, pathology associated with arterial stiffening will assume ever greater importance. Therefore, understanding these concepts for all clinicians involved in care of patients with cardiovascular disease will become vital.

  11. Leg Swelling

    Science.gov (United States)

    ... ed. New York, N.Y.: The McGraw Hill Companies; 2016. http://www.accessmedicine.com. Accessed Dec. 31, ... http://www.mayoclinic.org/symptoms/leg-swelling/basics/definition/SYM-20050910 . Mayo Clinic Footer Legal Conditions and ...

  12. The relationship between trunk muscle activation and trunk stiffness: examining a non-constant stiffness gain.

    Science.gov (United States)

    Brown, Stephen H M; McGill, Stuart M

    2010-12-01

    The relationship between muscle activation, force and stiffness needs to be known to interpret the stability state of the spine. To test the relationship between these variables, a quick release approach was used to match quantified torso stiffness with an EMG activation-based estimate of individual muscle stiffnesses. The relationship between activation, force and stiffness was modelled as k = q x F/l, where k, F and l are muscle stiffness, force and length, respectively, and q is the dimensionless stiffness gain relating these variables. Under the tested experimental scenario, the 'stiffness gain', q, which linked activation with stiffness, demonstrated a decreasing trend with increasing levels of torso muscle activation. This highlights the likelihood that the choice of a single q value may be over simplistic to relate force to stiffness in muscles that control the spine. This has implications for understanding the potential for spine instability in situations requiring high muscular demand.

  13. Hyaluronan protects against cartilage damage by decreasing stiffness and changing3-D microarchitecture of subchondral bone in guinea pig primary osteoarthrosis

    DEFF Research Database (Denmark)

    Ding, Ming

    significantly lower bone volume fraction, and typical rod-like structure. In the long-term study, these latter changes were more pronounced, with an additionally significant decrease in connectivity and bone surface density (Fig. 2). In the short-term study, HA-treated cortical bone had significantly greater...... HA on the articular cartilage and subchondral bone tissues were seen. HA protects against OA-related cartilage degradation to almost normal level, and effectively changes the subchondral bone tissue microarchitecture, collagen and mineral content and density without altering the mechanical properties...... of cancellous bone. The most striking features are the microarchitectural changes in the subchondral cancellous bone that lead to lower bone density and markedly rod-like structure, and thus reducing cartilage stress during impact loading. Still, the subchondral bone has a greater mineral concentration...

  14. Acute Effects of Constant-Angle and Constant-Torque Static Stretching on Passive Stiffness of the Posterior Hip and Thigh Muscles in Healthy, Young and Old Men.

    Science.gov (United States)

    Palmer, Ty B

    2017-07-24

    The purpose of this study was to examine the acute effects of constant-angle (CA) and constant-torque (CT) static stretching on passive stiffness of the posterior hip and thigh muscles in healthy, young and old men. Fifteen young (25±3 years) and 15 old (71±4 years) men underwent 2 passive straight-leg raise (SLR) assessments before and after 8 min of CA and CT stretching using an isokinetic dynamometer. Passive stiffness was calculated during each SLR as the slope of the final 10% of the angle-torque curve. The results indicated that passive stiffness decreased from pre- to post-stretching for both treatments (P≤0.001-0.002) and age groups (P≤0.001-0.046); however, greater decreases were observed for the CT than the CA stretching (P=0.045) and for the old than the young men (Pstretching. These findings suggest that holding stretches at a constant tension may be a more effective strategy for altering passive stiffness of the posterior hip and thigh muscles. The greater stretch-induced stiffness decreases observed for the older men provide support that acute static stretching may be particularly effective for reducing stiffness in the elderly. As a result, it may be advantageous to prescribe static stretching prior to exercise for older adults, as this may be used to elicit substantial declines in passive stiffness, which could help reduce the risk of subsequent injury events in this population.

  15. Broken Leg

    Science.gov (United States)

    ... the leg, which can result in a fracture. Stress fractures outside of sport situations are more common in people who have: ... shoes. Choose the appropriate shoe for your favorite sports or activities. And ... can prevent stress fractures. Rotate running with swimming or biking. If ...

  16. Spring-like leg behaviour, musculoskeletal mechanics and control in maximum and submaximum height human hopping

    NARCIS (Netherlands)

    Bobbert, M.F.

    2011-01-01

    The purpose of this study was to understand how humans regulate their 'leg stiffness' in hopping, and to determine whether this regulation is intended to minimize energy expenditure. 'Leg stiffness' is the slope of the relationship between ground reaction force and displacement of the centre of mass

  17. Night Leg Cramps

    Science.gov (United States)

    Symptoms Night leg cramps By Mayo Clinic Staff Night leg cramps, also called nocturnal leg cramps, are painful, involuntary contractions or spasms of muscles in your legs, usually occurring when you're in bed. Night ...

  18. Effect of boot shaft stiffness on stability joint energy and muscular co-contraction during walking on uneven surface.

    Science.gov (United States)

    Böhm, Harald; Hösl, Matthias

    2010-09-17

    Increased boot shaft stiffness may have a noticeable impact on the range of motion of the ankle joint. Therefore, the ability of the ankle joint to generate power for propulsion might be impaired. This might result in compensatory changes at the knee and hip joint. Besides, adaptability of the subtalar joint to uneven surface might be reduced, which could in turn affect stability. The aim of the study was therefore to investigate the influence of boot shaft stiffness on biomechanical gait parameters. Fifteen healthy young adults walked over coarse gravel wearing two different hiking boots that differed by 50% in passive shaft stiffness. Leg kinematics, kinetics and electromyography were measured. Gait velocity and indicators for stability were not different when walking with the hard and soft boot shaft over the gravel surface. However, the hard boot shaft decreased the ankle range of motion as well as the eccentric energy absorbed at the ankle joint. As a consequence, compensatory changes at the knee joint were observed. Co-contraction was increased, and greater eccentric energy was absorbed. Therefore, the efficiency of gait with hard boots might be decreased and joint loading at the knee might be increased, which might cause early fatigue of knee muscles during walking or hiking. The results of this study suggest that stiffness and blocking of joint motion at the ankle should not be equated with safety. A trade-off between lateral stiffness and free natural motion of the ankle joint complex might be preferable.

  19. Arterial Stiffness and Pharmacological Interventions – The TRanscend Arterial stiffNess Substudy (TRANS study

    Directory of Open Access Journals (Sweden)

    Jirar Topouchian

    2007-09-01

    Full Text Available Jirar Topouchian1, Ramzi El Feghali1, Bruno Pannier1, Shuyu Wang2, Feng Zhao3, Karel Smetana4, Koon Teo3, Roland Asmar11The CardioVascular Institute, Paris, France; 2Beijing Clinical Trial and Research Center, Beijing, China; 3Population Health Research Institute, Hamilton, Canada; 4Vojenska nemocnice Plzen, Pizen, Czech RepublicAbstract: The degree of arterial stiffness is correlated with the risk of cardiovascular diseases and it is a powerful predictor for morbidity and mortality. Studies have shown that arterial stiffness reduction is associated with an improvement in survival. Reduction of arterial stiffness by pharmacological drugs varies according to the drugs and doses used and duration of treatment. This effect on the arteries differs among the various classes of drugs and among individual drugs in the same class. Quantification of the stiffness and other properties of the arterial wall can be used to monitor the responses to therapy in individuals with hypertension and other cardiovascular diseases. These measures can then be used as surrogate markers for the risk of clinical events. Inhibition of the renin-angiotensin system (RAS is associated with an important decrease in cardiovascular risk. Findings from clinical trials support the hypothesis that the protective effects of RAS inhibition are partly independent from blood pressure reduction and related to several mechanisms including vascular protective effects. The aim of the TRanscend Arterial stiffNess Substudy (TRANS is to assess the effect of an angiotensin II receptor blocker (ARB, telmisartan, on the arterial stiffness in a subgroup of patients from the Telmisartan Randomized Assessment Study in aCE iNtolerant subjects with cardiovascular Disease (TRANSCEND trial. The TRANSCEND trial is an international, multicenter, randomized double blind placebo controlled trial of telmisartan that enrolled patients at high risk for cardiovascular events. Some clinical baseline data of the

  20. Leg Injuries and Disorders

    Science.gov (United States)

    Your legs are made up of bones, blood vessels, muscles, and other connective tissue. They are important for motion ... falling, or having an accident can damage your legs. Common leg injuries include sprains and strains, joint ...

  1. Peripheral artery disease - legs

    Science.gov (United States)

    Peripheral vascular disease; PVD; PAD; Arteriosclerosis obliterans; Blockage of leg arteries; Claudication; Intermittent claudication; Vaso-occlusive disease of the legs; Arterial insufficiency of ...

  2. A self-adjusting negative feedback joint controller for legs standing on moving substrates of unknown compliance

    Science.gov (United States)

    Schneider, Axel; Cruse, Holk; Fischer, Björn; Schmitz, Josef

    2007-05-01

    Some recent robot controllers for hexapod walking have been developed based on investigations of stick insects. These animals live in an unpredictable environment that consists of twigs and leaves. Supports like twigs, leaves and branches induce a considerable amount of movement to the legs and their elastic joints. Earlier studies proposed negative feedback PD-controllers to regulate the angles of the knee joints to handle this situation. Recent studies suggest that the behaviour of the joint controller depends on the compliance of the substrate the insect is standing on. On highly elastic substrates (e.g. leaves) the joint controller exhibits an I-characteristic. Deviations from the original position are compensated completely. On moderately elastic substrates (e.g. twigs) the joint controller comprises a P-characteristic. The leg attains a resting position that differs from the original position through application of a specific compensation force. On stiff substrates the knee joint seems to be controlled by a D-controller. If the leg endpoint is forced away from the original position by an external disturbance (e.g. a moving branch), the controller compensates this deviation by activation of the according muscle which results in a counter force. After some time the controller seems to "give up." The force decreases to zero. To model these results, we propose a self-adjusting joint controller that changes its own setpoint in dependance of the substrate stiffness. The substrate stiffness is determined by means of a correlator circuit that compares (superimposed) movement commands with the actual responses of the leg joint. The new controller can be used for the control of legged robots.

  3. Terminology: resistance or stiffness for medical compression stockings?

    Directory of Open Access Journals (Sweden)

    André Cornu-Thenard

    2013-04-01

    Full Text Available Based on previous experimental work with medical compression stockings it is proposed to restrict the term stiffness to measurements on the human leg and rather to speak about resistance when it comes to characterize the elastic property of compression hosiery in the textile laboratory.

  4. Variable bipedal walking gait with variable leg stiffness

    NARCIS (Netherlands)

    Roozing, W.M.; Visser, L.C.; Carloni, Raffaella

    The Spring-Loaded Inverted Pendulum (SLIP) model has been shown to exhibit many properties of human walking, and therefore has been the starting point for studies on robust, energy-efficient walking for robots. In this paper, the problem of gait variation during walking on the SLIP model is

  5. Big bang nucleosynthesis with a stiff fluid

    International Nuclear Information System (INIS)

    Dutta, Sourish; Scherrer, Robert J.

    2010-01-01

    Models that lead to a cosmological stiff fluid component, with a density ρ S that scales as a -6 , where a is the scale factor, have been proposed recently in a variety of contexts. We calculate numerically the effect of such a stiff fluid on the primordial element abundances. Because the stiff fluid energy density decreases with the scale factor more rapidly than radiation, it produces a relatively larger change in the primordial helium-4 abundance than in the other element abundances, relative to the changes produced by an additional radiation component. We show that the helium-4 abundance varies linearly with the density of the stiff fluid at a fixed fiducial temperature. Taking ρ S10 and ρ R10 to be the stiff fluid energy density and the standard density in relativistic particles, respectively, at T=10 MeV, we find that the change in the primordial helium abundance is well-fit by ΔY p =0.00024(ρ S10 /ρ R10 ). The changes in the helium-4 abundance produced by additional radiation or by a stiff fluid are identical when these two components have equal density at a 'pivot temperature', T * , where we find T * =0.55 MeV. Current estimates of the primordial 4 He abundance give the constraint on a stiff fluid energy density of ρ S10 /ρ R10 <30.

  6. Skipping on uneven ground: trailing leg adjustments simplify control and enhance robustness

    Science.gov (United States)

    2018-01-01

    It is known that humans intentionally choose skipping in special situations, e.g. when descending stairs or when moving in environments with lower gravity than on Earth. Although those situations involve uneven locomotion, the dynamics of human skipping on uneven ground have not yet been addressed. To find the reasons that may motivate this gait, we combined experimental data on humans with numerical simulations on a bipedal spring-loaded inverted pendulum model (BSLIP). To drive the model, the following parameters were estimated from nine subjects skipping across a single drop in ground level: leg lengths at touchdown, leg stiffness of both legs, aperture angle between legs, trailing leg angle at touchdown (leg landing first after flight phase), and trailing leg retraction speed. We found that leg adjustments in humans occur mostly in the trailing leg (low to moderate leg retraction during swing phase, reduced trailing leg stiffness, and flatter trailing leg angle at lowered touchdown). When transferring these leg adjustments to the BSLIP model, the capacity of the model to cope with sudden-drop perturbations increased. PMID:29410879

  7. Interaction Between Leg Muscle Performance and Sprint Acceleration Kinematics

    Directory of Open Access Journals (Sweden)

    Lockie Robert G.

    2015-12-01

    Full Text Available This study investigated relationships between 10 m sprint acceleration, step kinematics (step length and frequency, contact and flight time, and leg muscle performance (power, stiffness, strength. Twenty-eight field sport athletes completed 10 m sprints that were timed and filmed. Velocity and step kinematics were measured for the 0-5, 5-10, and 0-10 m intervals to assess acceleration. Leg power was measured via countermovement jumps (CMJ, a fivebound test (5BT, and the reactive strength index (RSI defined by 40 cm drop jumps. Leg stiffness was measured by bilateral and unilateral hopping. A three-repetition maximum squat determined strength. Pearson’s correlations and stepwise regression (p ≤ 0.05 determined velocity, step kinematics, and leg muscle performance relationships. CMJ height correlated with and predicted velocity in all intervals (r = 0.40-0.54. The 5BT (5-10 and 0-10 m intervals and RSI (5-10 m interval also related to velocity (r = 0.37-0.47. Leg stiffness did not correlate with acceleration kinematics. Greater leg strength related to and predicted lower 0-5 m flight times (r = -0.46 to -0.51, and a longer 0-10 m step length (r = 0.38. Although results supported research emphasizing the value of leg power and strength for acceleration, the correlations and predictive relationships (r2 = 0.14-0.29 tended to be low, which highlights the complex interaction between sprint technique and leg muscle performance. Nonetheless, given the established relationships between speed, leg power and strength, strength and conditioning coaches should ensure these qualities are expressed during acceleration in field sport athletes.

  8. Interaction Between Leg Muscle Performance and Sprint Acceleration Kinematics.

    Science.gov (United States)

    Lockie, Robert G; Jalilvand, Farzad; Callaghan, Samuel J; Jeffriess, Matthew D; Murphy, Aron J

    2015-12-22

    This study investigated relationships between 10 m sprint acceleration, step kinematics (step length and frequency, contact and flight time), and leg muscle performance (power, stiffness, strength). Twenty-eight field sport athletes completed 10 m sprints that were timed and filmed. Velocity and step kinematics were measured for the 0-5, 5-10, and 0-10 m intervals to assess acceleration. Leg power was measured via countermovement jumps (CMJ), a five-bound test (5BT), and the reactive strength index (RSI) defined by 40 cm drop jumps. Leg stiffness was measured by bilateral and unilateral hopping. A three-repetition maximum squat determined strength. Pearson's correlations and stepwise regression (p ≤ 0.05) determined velocity, step kinematics, and leg muscle performance relationships. CMJ height correlated with and predicted velocity in all intervals (r = 0.40-0.54). The 5BT (5-10 and 0-10 m intervals) and RSI (5-10 m interval) also related to velocity (r = 0.37-0.47). Leg stiffness did not correlate with acceleration kinematics. Greater leg strength related to and predicted lower 0-5 m flight times (r = -0.46 to -0.51), and a longer 0-10 m step length (r = 0.38). Although results supported research emphasizing the value of leg power and strength for acceleration, the correlations and predictive relationships (r(2) = 0.14-0.29) tended to be low, which highlights the complex interaction between sprint technique and leg muscle performance. Nonetheless, given the established relationships between speed, leg power and strength, strength and conditioning coaches should ensure these qualities are expressed during acceleration in field sport athletes.

  9. Leg lengthening - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100127.htm Leg lengthening - series—Indications To use the sharing features ... with lengthening procedures are the bones of the leg, the tibia and the femur. Surgical treatment may ...

  10. Arterial bypass leg - slideshow

    Science.gov (United States)

    ... medlineplus.gov/ency/presentations/100155.htm Arterial bypass leg - series—Normal anatomy To use the sharing features ... Overview The arteries which supply blood to the leg originate from the aorta and iliac vessels. Review ...

  11. Leg lengthening and shortening

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002965.htm Leg lengthening and shortening To use the sharing features on this page, please enable JavaScript. Leg lengthening and shortening are types of surgery to ...

  12. Scaling of the Spring in the Leg during Bouncing Gaits of Mammals

    Science.gov (United States)

    Lee, David V.; Isaacs, Michael R.; Higgins, Trevor E.; Biewener, Andrew A.; McGowan, Craig P.

    2014-01-01

    Trotting, bipedal running, and especially hopping have long been considered the principal bouncing gaits of legged animals. We use the radial-leg spring constant krad to quantify the stiffness of the physical leg during bouncing gaits. The radial-leg is modeled as an extensible strut between the hip and the ground and krad is determined from the force and deflection of this strut in each instance of stance. A Hookean spring is modeled in-series with a linear actuator and the stiffness of this spring krad is determined by minimizing the work of the actuator while reproducing the measured force-deflection dynamics of an individual leg during trotting or running, and of the paired legs during hopping. Prior studies have estimated leg stiffness using kleg, a metric that imagines a virtual-leg connected to the center of mass. While kleg has been applied extensively in human and comparative biomechanics, we show that krad more accurately models the spring in the leg when actuation is allowed, as is the case in biological and robotic systems. Our allometric analysis of krad in the kangaroo rat, tammar wallaby, dog, goat, and human during hopping, trotting, or running show that krad scales as body mass to the two-third power, which is consistent with the predictions of dynamic similarity and with the scaling of kleg. Hence, two-third scaling of locomotor spring constants among mammals is supported by both the radial-leg and virtual-leg models, yet the scaling of krad emerges from work-minimization in the radial-leg model instead of being a defacto result of the ratio of force to length used to compute kleg. Another key distinction between the virtual-leg and radial-leg is that krad is substantially greater than kleg, as indicated by a 30–37% greater scaling coefficient for krad. We also show that the legs of goats are on average twice as stiff as those of dogs of the same mass and that goats increase the stiffness of their legs, in part, by more nearly aligning their

  13. Foot, leg, and ankle swelling

    Science.gov (United States)

    Swelling of the ankles - feet - legs; Ankle swelling; Foot swelling; Leg swelling; Edema - peripheral; Peripheral edema ... Foot, leg, and ankle swelling is common when the person also: Is overweight Has a blood clot in the leg Is older Has ...

  14. Stiff Quantum Polymers

    OpenAIRE

    Kleinert, H.

    2007-01-01

    At ultralow temperatures, polymers exhibit quantum behavior, which is calculated here for the second and fourth moments of the end-to-end distribution in the large-stiffness regime. The result should be measurable for polymers in wide optical traps.

  15. Compression Stockings for Treating Venous Leg Ulcers

    Directory of Open Access Journals (Sweden)

    J. P. Benigni

    2013-01-01

    Full Text Available Background. In order to treat venous leg ulcers, it is recommended to use high pressure compression (30–40 mmHg at the ankle. Compression stockings which are not operator dependant could be the best option because of their pressure control. However 30–40 mmHg compression stockings are often hard to put on. Putting two lower pressure compression stockings over each other could be a good therapeutic alternative. Objectives. To compare the in vitro pressures given by the manufacturers of 2 antiulcer kits with the in vivo interface pressures measured in healthy subjects and to evaluate the stiffness and friction indices from those kits based on the interface pressure in order to assess their clinical properties. Material and Methods. Using a Kikuhime pressure device, interface pressure was measured in 12 healthy subjects at the reference point B1. One stiffness index (Static Stiffness Index (SSI and a friction index have been calculated. Results. Mediven Ulcer kit gets the recommended pressures whereas Jobst’s Ulcer Care kit does not for treating a venous leg ulcer. Jobst’s Ulcer Care transmits entirely the pressure in relation to a friction index close to 1. Conclusion. This antiulcer kit study underlines that in vivo and in vitro pressures can be different (Jobst’s Ulcer Care kit and Mediven Ulcer kit. In order not to lose pressure, it is important to take into account the friction index when superimposing two stockings.

  16. Symptom Severity of Restless Legs Syndrome Predicts Its Clinical Course.

    Science.gov (United States)

    Lee, Chung Suk; Kim, Tae; Lee, Sumin; Jeon, Hong Jun; Bang, Young Rong; Yoon, In-Young

    2016-04-01

    This study examines the clinical course of restless legs syndrome according to its severity and factors associated with the remission of restless legs syndrome symptoms. The remission or persistence of restless legs syndrome symptoms was investigated by considering patients with restless legs syndrome at the sleep clinic of Seoul National University Bundang Hospital. All subjects were observed for at least 18 months, and an incidence of remission was defined as having no restless legs syndrome symptoms for at least 1 year. Restless legs syndrome severity was evaluated by the International Restless Legs Syndrome Study Group Rating Scale. A total of 306 patients participated in this study. Over the observation periods of 4.1 ± 1.6 years, the cumulative incidence of remission is 32.5% (95% confidence interval [CI], 27.0-38.0) and decreased with baseline restless legs syndrome severity (P restless legs syndrome cases, respectively. Most cases of remission (82/96) were observed within 1 year, and the remission occurred sooner for mild restless legs syndrome. The hazard ratios of remission by Cox proportional hazards model were lower for moderate (0.556; 95% CI, 0.340-0.909) and severe to very severe (0.193; 95% CI, 0.108-0.343) restless legs syndrome than for mild restless legs syndrome. The remission incidence was lower for those patients who had a family history of restless legs syndrome and were older at restless legs syndrome diagnosis. Mild restless legs syndrome severity, no family history, and young age at restless legs syndrome diagnosis were significant predictors of restless legs syndrome remission. More than 80% of patients with severe restless legs syndrome showed a chronic clinical course. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Finite-state transition system analysis of disturbed foundation stiffness

    DEFF Research Database (Denmark)

    Sabaliauskas, Tomas; Ibsen, Lars Bo

    2018-01-01

    Foundations erected in sand can become disturbed during dynamic loading, as sand stiffness can both increase and decrease episodically. Paradigms outside geotechnics analyze similar problems as finite-state transition systems. Therefore, patterns governing disturbed foundation stiffness change......, the unconventional analysis technique delivers substantial descriptive and predictive power. To demonstrate the utility, stiffness of a foundation prototype is manipulated: during real-life, real-time testing, the initial stiffness path is disturbed and recovered 5 times in one loading sequence. Thus, the "memory...

  18. Aortic stiffness and the balance between cardiac oxygen supply and demand: the Rotterdam Study

    NARCIS (Netherlands)

    Guelen, Ilja; Mattace-Raso, Francesco U. S.; van Popele, Nicole M.; Westerhof, Berend E.; Hofman, Albert; Witteman, Jacqueline C. M.; Bos, Willem Jan W.

    2008-01-01

    OBJECTIVES: Aortic stiffness is an independent predictor of cardiovascular morbidity and mortality. We investigated whether aortic stiffness, estimated as aortic pulse wave velocity, is associated with decreased perfusion pressure estimated as the cardiac oxygen supply potential. METHODS: Aortic

  19. Stiffness Evolution in Frozen Sands Subjected to Stress Changes

    KAUST Repository

    Dai, Sheng

    2017-04-21

    Sampling affects all soils, including frozen soils and hydrate-bearing sediments. The authors monitor the stiffness evolution of frozen sands subjected to various temperature and stress conditions using an oedometer cell instrumented with P-wave transducers. Experimental results show the stress-dependent stiffness of freshly remolded sands, the dominant stiffening effect of ice, creep after unloading, and the associated exponential decrease in stiffness with time. The characteristic time for stiffness loss during creep is of the order of tens of minutes; therefore it is inevitable that frozen soils experience sampling disturbances attributable to unloading. Slow unloading minimizes stiffness loss; conversely, fast unloading causes a pronounced reduction in stiffness probably attributable to the brittle failure of ice or ice-mineral bonding.

  20. Leg blood flow during static exercise.

    Science.gov (United States)

    Kilbom, A; Persson, J

    1982-01-01

    Leg blood flow was studied with the constant infusion dye technique during static exercise of the thigh muscles (quadriceps) and during hand-grips at 15 and 25-30% of MVC. Blood flow and oxygen uptake in the leg increased in quadriceps exercise and reached their highest values (around 1.21/min and 165 ml/min respectively) at 25-30% of MVC, whereas leg vascular resistance decreased. Regional circulatory adaptations and the oxygen uptake - leg blood flow relationship were in close agreement with the responses found in dynamic leg exercise. In view of the marked rise in intramuscular pressure previously observed during quadriceps contractions, a restriction of blood flow and an increased vascular resistance had been expected. Involuntary activation of leg muscles other than the quadriceps may explain the finding. Contractions of the contralateral quadriceps induced a slight increase in leg blood flow, whereas hand-grips had no influence on blood flow or vascular resistance in the leg. The distribution of the cardiac output during static contractions is discussed, and it is concluded that during hand-grips the increase in blood flow is predominantly distributed to the upper part of the body.

  1. Venous leg ulcers.

    Science.gov (United States)

    Nelson, E Andrea; Adderley, Una

    2016-01-15

    Leg ulcers usually occur secondary to venous reflux or obstruction, but 20% of people with leg ulcers have arterial disease, with or without venous disorders. Between 1.5 and 3.0 in 1000 people have active leg ulcers. Prevalence increases with age to about 20 in 1000 people aged over 80 years. We conducted a systematic overview, aiming to answer the following clinical questions: What are the effects of treatments for venous leg ulcers? What are the effects of organisational interventions for venous leg ulcers? What are the effects of advice about self-help interventions in people receiving usual care for venous leg ulcers? What are the effects of interventions to prevent recurrence of venous leg ulcers? We searched: Medline, Embase, The Cochrane Library, and other important databases up to March 2014 (Clinical Evidence overviews are updated periodically; please check our website for the most up-to-date version of this overview). At this update, searching of electronic databases retrieved 116 studies. After deduplication and removal of conference abstracts, 63 records were screened for inclusion in the overview. Appraisal of titles and abstracts led to the exclusion of 43 studies and the further review of 20 full publications. Of the 20 full articles evaluated, four systematic reviews were updated and four RCTs were added at this update. We performed a GRADE evaluation for 23 PICO combinations. In this systematic overview, we categorised the efficacy for 13 interventions based on information about the effectiveness and safety of advice to elevate leg, advice to keep leg active, compression stockings for prevention of recurrence, compression bandages and stockings to treat venous leg ulcers, laser treatment (low level), leg ulcer clinics, pentoxifylline, skin grafting, superficial vein surgery for prevention of recurrence, superficial vein surgery to treat venous leg ulcers, therapeutic ultrasound, and topical negative pressure.

  2. On gear tooth stiffness evaluation

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard; Jørgensen, Martin Felix

    2014-01-01

    The estimation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. Two factors have a major influence on the stiffness; firstly the boundary condition through the gear rim size included in the stiffness calculation...... and secondly the size of the contact. In the FE calculation the true gear tooth root profile is applied. The meshing stiffnesses of gears are highly non-linear, it is however found that the stiffness of an individual tooth can be expressed in a linear form assuming that the contact width is constant. © 2014...... Elsevier Ltd. All rights reserved....

  3. Dynamically Stable Legged Locomotion.

    Science.gov (United States)

    1983-01-27

    balanced itself in 31) using a tabular ctontrol sclwnme. With only thUiee actuated degrees it used a shuffling gait to balance that reminds one of Charlie ... Chaplin . * The present study explores the control of a physical one-legged hopping machine. The objective of using a machine with only one leg was to

  4. Lyden-af-Leg

    DEFF Research Database (Denmark)

    Toft, Herdis

    Præsentation af seniorforsker-projekt Lyden-af-Leg i et traderingsperspektiv og med indledende fokus på YouTube som traderings-platform.......Præsentation af seniorforsker-projekt Lyden-af-Leg i et traderingsperspektiv og med indledende fokus på YouTube som traderings-platform....

  5. A novel variable stiffness mechanism for dielectric elastomer actuators

    Science.gov (United States)

    Li, Wen-Bo; Zhang, Wen-Ming; Zou, Hong-Xiang; Peng, Zhi-Ke; Meng, Guang

    2017-08-01

    In this paper, a novel variable stiffness mechanism is proposed for the design of a variable stiffness dielectric elastomer actuator (VSDEA) which combines a flexible strip with a DEA in a dielectric elastomer minimum energy structure. The DEA induces an analog tuning of the transverse curvature of the strip, thus conveniently providing a voltage-controllable flexural rigidity. The VSDEA tends to be a fully flexible and compact structure with the advantages of simplicity and fast response. Both experimental and theoretical investigations are carried out to reveal the variable stiffness performances of the VSDEA. The effect of the clamped location on the bending stiffness of the VSDEA is analyzed, and then effects of the lengths, the loading points and the applied voltages on the bending stiffness are experimentally investigated. An analytical model is developed to verify the availability of this variable stiffness mechanism, and the theoretical results demonstrate that the bending stiffness of the VSDEA decreases as the applied voltage increases, which agree well with the experimental data. Moreover, the experimental results show that the maximum change of the relative stiffness can reach about 88.80%. It can be useful for the design and optimization of active variable stiffness structures and DEAs for soft robots, vibration control, and morphing applications.

  6. Stiffness, resilience, compressibility

    Energy Technology Data Exchange (ETDEWEB)

    Leu, Bogdan M. [Argonne National Laboratory, Advanced Photon Source (United States); Sage, J. Timothy, E-mail: jtsage@neu.edu [Northeastern University, Department of Physics and Center for Interdisciplinary Research on Complex Systems (United States)

    2016-12-15

    The flexibility of a protein is an important component of its functionality. We use nuclear resonance vibrational spectroscopy (NRVS) to quantify the flexibility of the heme iron environment in the electron-carrying protein cytochrome c by measuring the stiffness and the resilience. These quantities are sensitive to structural differences between the active sites of different proteins, as illustrated by a comparative analysis with myoglobin. The elasticity of the entire protein, on the other hand, can be probed quantitatively from NRVS and high energy-resolution inelastic X-ray scattering (IXS) measurements, an approach that we used to extract the bulk modulus of cytochrome c.

  7. Predictive simulation of diabetic gait: Individual contribution of ankle stiffness and muscle weakening.

    Science.gov (United States)

    Santos, Gilmar F; Gomes, Aline A; Sacco, Isabel C N; Ackermann, Marko

    2017-10-01

    Diabetic neuropathic individuals present massive muscle strength reduction at the ankle plantar- and dorsiflexors and increased joint stiffness. Our aim is to investigate the adaptation strategies to these musculoskeletal alterations during walking by means of predictive simulations. We used a seven segment planar musculoskeletal model actuated by eight Hill-type muscles in each leg. The effect of all passive tissue in muscles and other joint structures was modeled by net passive joint moment curves. The predictive simulations were generated by solving an optimal control problem that minimized a cost function, including effort and tracking terms, using direct collocation and a commercial optimal control package. We simulate four conditions to represent the weakening of the distal muscles triceps sural (TS) and tibialis anterior (TA), and five conditions to represent the effect of increasing nonlinear ankle stiffness in flexion. The weakening of the distal muscles leads to a delayed action of the TS and a progressive decrease of the gastrocnemius peak force in the push-off phase. This distal deficit is compensated by a larger hip flexion moment resulting from an increase in the iliopsoas muscle force in this phase, known as the hip strategy. The adaptation mechanisms observed in response to an increase in ankle stiffness include the hip strategy and the exploitation of the passive joint structures as springs, which store energy during midstance and release it during push-off, reducing TS force and power in this phase and leading to a consistent decrease in the overall muscle force levels. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Pharmacological modulation of arterial stiffness.

    LENUS (Irish Health Repository)

    Boutouyrie, Pierre

    2011-09-10

    Arterial stiffness has emerged as an important marker of cardiovascular risk in various populations and reflects the cumulative effect of cardiovascular risk factors on large arteries, which in turn is modulated by genetic background. Arterial stiffness is determined by the composition of the arterial wall and the arrangement of these components, and can be studied in humans non-invasively. Age and distending pressure are two major factors influencing large artery stiffness. Change in arterial stiffness with drugs is an important endpoint in clinical trials, although evidence for arterial stiffness as a therapeutic target still needs to be confirmed. Drugs that independently affect arterial stiffness include antihypertensive drugs, mostly blockers of the renin-angiotensin-aldosterone system, hormone replacement therapy and some antidiabetic drugs such as glitazones. While the quest continues for \\'de-stiffening drugs\\

  9. IMPACT TESTING OF THE RESIDUAL LIMB: SYSTEM RESPONSE TO CHANGES IN PROSTHETIC STIFFNESS

    OpenAIRE

    Boutwell, Erin; Stine, Rebecca; Gard, Steven

    2016-01-01

    Currently, it is unknown whether changing prosthetic limb stiffness affects the total limb stiffness and influences the shock absorption of an individual with transtibial amputation. The hypotheses tested within this study are that a decrease in longitudinal prosthetic stiffness will produce (1) a reduced total limb stiffness; and (2) reduced magnitude of peak impact forces and increased time delay to peak force. Fourteen subjects with a transtibial amputation participated in this study. Pros...

  10. Dynamic stiffness of suction caissons

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten; Andersen, Lars

    The purpose of this report is to evaluate the dynamic soil-structure interaction of suction caissons for offshore wind turbines. The investigation is limited to a determination of the vertical dynamic stiffness of suction caissons. The soil surrounding the foundation is homogenous with linear...... viscoelastic properties. The dynamic stiffness of the suction caisson is expressed by dimensionless frequency-dependent dynamic stiffness coefficients corresponding to the vertical degree of freedom. The dynamic stiffness coefficients for the foundations are evaluated by means of a dynamic three...

  11. Changes in force and stiffness after static stretching of eccentrically-damaged hamstrings.

    Science.gov (United States)

    Matsuo, Shingo; Suzuki, Shigeyuki; Iwata, Masahiro; Hatano, Genki; Nosaka, Kazunori

    2015-05-01

    This study compared responses to static stretching between eccentrically damaged and non-damaged muscles. Twelve young men performed 60 maximum knee flexor eccentric contractions of one leg, and received a 300-s continuous passive static stretching at tolerable intensity without pain to both knee flexors at 2 and 4 days after the eccentric exercise. Range of motion (ROM) and passive stiffness during knee extension, passive torque at onset of pain (PT), maximum voluntary isometric (MVC-ISO) and isokinetic concentric contraction torque (MVC-CON), and visual analogue scale (VAS) for muscle soreness were measured before, immediately after, 60 min, 2 and 4 days after exercise as well as before, immediately after, 20 and 60 min after the stretching. Changes in these variables after eccentric exercise and stretching were compared between limbs. The eccentric exercise decreased MVC-ISO, MVC-CON, ROM and PT, and increased passive stiffness and VAS (p static stretching at tolerable intensity without pain produced greater positive effects on damaged than non-damaged muscles.

  12. RESTLESS LEGS SYNDROME

    Directory of Open Access Journals (Sweden)

    Dmitriy Valer'evich Artem'ev

    2009-01-01

    Full Text Available The paper describes the epidemiology, etiology, pathogenesis, clinical picture, diagnosis, differential diagnosis, and treatment of restless legs syndrome. Recommendations are given how to choose therapeutic modalities and drugs in relation to different factors.

  13. Restless legs syndrome.

    Science.gov (United States)

    Venkateshiah, Saiprakash B; Ioachimescu, Octavian C

    2015-07-01

    Restless legs syndrome is a common sensorimotor disorder characterized by an urge to move, and associated with uncomfortable sensations in the legs (limbs). Restless legs syndrome can lead to sleep-onset or sleep-maintenance insomnia, and occasionally excessive daytime sleepiness, all leading to significant morbidity. Brain iron deficiency and dopaminergic neurotransmission abnormalities play a central role in the pathogenesis of this disorder, along with other nondopaminergic systems, although the exact mechanisms are still. Intensive care unit patients are especially vulnerable to have unmasking or exacerbation of restless legs syndrome because of sleep deprivation, circadian rhythm disturbance, immobilization, iron deficiency, and use of multiple medications that can antagonize dopamine. Published by Elsevier Inc.

  14. Profile of altered brain iron acquisition in restless legs syndrome

    Science.gov (United States)

    Ponnuru, Padmavathi; Wang, Xin-Sheng; Patton, Stephanie M.; Allen, Richard P.; Earley, Christopher J.

    2011-01-01

    Restless legs syndrome is a neurological disorder characterized by an urgency to move the legs during periods of rest. Data from a variety of sources provide a compelling argument that the amount of iron in the brain is lower in individuals with restless legs syndrome compared with neurologically normal individuals. Moreover, a significant percentage of patients with restless legs syndrome are responsive to intravenous iron therapy. The mechanism underlying the decreased iron concentrations in restless legs syndrome brains is unknown. We hypothesize that the source of the brain iron deficit is at the blood–brain interface. Thus we analysed the expression of iron management proteins in the epithelial cells of the choroid plexus and the brain microvasculature in post-mortem tissues. The choroid plexus, obtained at autopsy, from 18 neurologically normal controls and 14 individuals who had primary restless legs syndrome was subjected to histochemical staining for iron and immunostaining for iron management proteins. Iron and heavy chain ferritin staining was reduced in the epithelial cells of choroid plexus in restless legs syndrome. Divalent metal transporter, ferroportin, transferrin and its receptor were upregulated in the choroid plexus in restless legs syndrome. Microvessels were isolated from the motor cortex of 11 restless legs syndrome and 14 control brains obtained at autopsy and quantitative immunoblot analyses was performed. Expression of heavy chain ferritin, transferrin and its receptor in the microvessels from restless legs syndrome was significantly decreased compared with the controls but divalent metal protein 1, ferroportin, prohepcidin, mitochondrial ferritin and light-chain ferritin remained unchanged. The presence of an iron regulatory protein was demonstrated in the brain microvasculature and the activity of this protein is decreased in restless legs syndrome; a finding similar to our earlier report in neuromelanin cells from the substantia

  15. Numerical integrators for Stiff and Stiff oscillatory First Order initial ...

    African Journals Online (AJOL)

    Numerical integrators for Stiff and Stiff oscillatory First Order initial value problems. ... Journal of the Nigerian Association of Mathematical Physics ... In this paper, efforts are geared towards the numerical solution of the first order initial value problem (I.V.P) of the form Y\\' = F(X,Y), X∈[ a, b] , Y(a) = Y0, where Y\\' is the total ...

  16. Limit cycles and stiffness control with variable stiffness actuators

    NARCIS (Netherlands)

    Carloni, Raffaella; Marconi, L.

    2012-01-01

    Variable stiffness actuators realize highly dynamic systems, whose inherent mechanical compliance can be properly exploited to obtain a robust and energy-efficient behavior. The paper presents a control strategy for variable stiffness actuators with the primarily goal of tracking a limit cycle

  17. Extracellular Matrix Stiffness Regulates Osteogenic Differentiation through MAPK Activation.

    Directory of Open Access Journals (Sweden)

    Jun-Ha Hwang

    Full Text Available Mesenchymal stem cell (MSC differentiation is regulated by the extracellular matrix (ECM through activation of intracellular signaling mediators. The stiffness of the ECM was shown to be an important regulatory factor for MSC differentiation, and transcriptional coactivator with PDZ-binding motif (TAZ was identified as an effector protein for MSC differentiation. However, the detailed underlying mechanism regarding the role of ECM stiffness and TAZ in MSC differentiation is not yet fully understood. In this report, we showed that ECM stiffness regulates MSC fate through ERK or JNK activation. Specifically, a stiff hydrogel matrix stimulates osteogenic differentiation concomitant with increased nuclear localization of TAZ, but inhibits adipogenic differentiation. ERK and JNK activity was significantly increased in cells cultured on a stiff hydrogel. TAZ activation was induced by ERK or JNK activation on a stiff hydrogel because exposure to an ERK or JNK inhibitor significantly decreased the nuclear localization of TAZ, indicating that ECM stiffness-induced ERK or JNK activation is important for TAZ-driven osteogenic differentiation. Taken together, these results suggest that ECM stiffness regulates MSC differentiation through ERK or JNK activation.

  18. STRETCHING EXERCISES - EFFECT ON PASSIVE EXTENSIBILITY AND STIFFNESS IN SHORT HAMSTRINGS OF HEALTHY-SUBJECTS

    NARCIS (Netherlands)

    HALBERTSMA, JPK; GOEKEN, LNH

    Passive muscle stretch tests are common practice in physical therapy and rehabilitation medicine. However, the effects of stretching exercises are not well known. With an instrumental straight-leg-raising set-up the extensibility, stiffness, and electromyographic activity of the hamstring muscles

  19. Impact testing of the residual limb: System response to changes in prosthetic stiffness.

    Science.gov (United States)

    Boutwell, Erin; Stine, Rebecca; Gard, Steven

    2016-01-01

    Currently, it is unknown whether changing prosthetic limb stiffness affects the total limb stiffness and influences the shock absorption of an individual with transtibial amputation. The hypotheses tested within this study are that a decrease in longitudinal prosthetic stiffness will produce (1) a reduced total limb stiffness, and (2) reduced magnitude of peak impact forces and increased time delay to peak force. Fourteen subjects with a transtibial amputation participated in this study. Prosthetic stiffness was modified by means of a shock-absorbing pylon that provides reduced longitudinal stiffness through compression of a helical spring within the pylon. A sudden loading evaluation device was built to examine changes in limb loading mechanics during a sudden impact event. No significant change was found in the peak force magnitude or timing of the peak force between prosthetic limb stiffness conditions. Total limb stiffness estimates ranged from 14.9 to 17.9 kN/m but were not significantly different between conditions. Thus, the prosthetic-side total limb stiffness was unaffected by changes in prosthetic limb stiffness. The insensitivity of the total limb stiffness to prosthetic stiffness may be explained by the mechanical characteristics (i.e., stiffness and damping) of the anatomical tissue within the residual limb.

  20. Reconstruction of human swing leg motion with passive biarticular muscle models.

    Science.gov (United States)

    Ahmad Sharbafi, Maziar; Mohammadi Nejad Rashty, Aida; Rode, Christian; Seyfarth, Andre

    2017-04-01

    Template models, which are utilized to demonstrate general aspects in human locomotion, mostly investigate stance leg operation. The goal of this paper is presenting a new conceptual walking model benefiting from swing leg dynamics. Considering a double pendulum equipped with combinations of biarticular springs for the swing leg beside spring-mass (SLIP) model for the stance leg, a novel SLIP-based model, is proposed to explain human-like leg behavior in walking. The action of biarticular muscles in swing leg motion helps represent human walking features, like leg retraction, ground reaction force and generating symmetric walking patterns, in simulations. In order to stabilize the motion by the proposed passive structure, swing leg biarticular muscle parameters such as lever arm ratios, stiffnesses and rest lengths need to be properly adjusted. Comparison of simulation results with human experiments shows the ability of the proposed model in replicating kinematic and kinetic behavior of both stance and swing legs as well as biarticular thigh muscle force of the swing leg. This substantiates the important functional role of biarticular muscles in leg swing. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Venous leg ulcers.

    Science.gov (United States)

    Nelson, E Andrea

    2011-12-21

    Leg ulcers usually occur secondary to venous reflux or obstruction, but 20% of people with leg ulcers have arterial disease, with or without venous disorders. Between 1.5 and 3.0/1000 people have active leg ulcers. Prevalence increases with age to about 20/1000 in people aged over 80 years. We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of standard treatments, adjuvant treatments, and organisational interventions for venous leg ulcers? What are the effects of advice about self-help interventions in people receiving usual care for venous leg ulcers? What are the effects of interventions to prevent recurrence of venous leg ulcers? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2011 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 101 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: compression bandages and stockings, cultured allogenic (single or bilayer) skin replacement, debriding agents, dressings (cellulose, collagen, film, foam, hyaluronic acid-derived, semi-occlusive alginate), hydrocolloid (occlusive) dressings in the presence of compression, intermittent pneumatic compression, intravenous prostaglandin E1, larval therapy, laser treatment (low-level), leg ulcer clinics, multilayer elastic system, multilayer elastomeric (or non-elastomeric) high-compression regimens or bandages, oral treatments (aspirin, flavonoids, pentoxifylline, rutosides, stanozolol, sulodexide

  2. Role of flexural stiffness of leukocyte microvilli in adhesion dynamics

    Science.gov (United States)

    Wu, Tai-Hsien; Qi, Dewei

    2018-03-01

    Previous work reported that microvillus deformation has an important influence on dynamics of cell adhesion. However, the existing studies were limited to the extensional deformation of microvilli and did not consider the effects of their bending deformation on cell adhesion. This Rapid Communication investigates the effects of flexural stiffness of microvilli on the rolling process related to adhesion of leukocytes by using a lattice-Boltzmann lattice-spring method (LLM) combined with adhesive dynamics (AD) simulations. The simulation results reveal that the flexural stiffness of microvilli and their bending deformation have a profound effect on rolling velocity and adhesive forces. As the flexural stiffness of the microvilli decreases, their bending angles increase, resulting in an increase in the number of receptor-ligand bonds and adhesive bonding force and a decrease in the rolling velocity of leukocytes. The effects of flexural stiffness on deformation and adhesion represent crucial factors involved in cell adhesion.

  3. Arterial stiffness and cognitive impairment.

    Science.gov (United States)

    Li, Xiaoxuan; Lyu, Peiyuan; Ren, Yanyan; An, Jin; Dong, Yanhong

    2017-09-15

    Arterial stiffness is one of the earliest indicators of changes in vascular wall structure and function and may be assessed using various indicators, such as pulse-wave velocity (PWV), the cardio-ankle vascular index (CAVI), the ankle-brachial index (ABI), pulse pressure (PP), the augmentation index (AI), flow-mediated dilation (FMD), carotid intima media thickness (IMT) and arterial stiffness index-β. Arterial stiffness is generally considered an independent predictor of cardiovascular and cerebrovascular diseases. To date, a significant number of studies have focused on the relationship between arterial stiffness and cognitive impairment. To investigate the relationships between specific arterial stiffness parameters and cognitive impairment, elucidate the pathophysiological mechanisms underlying the relationship between arterial stiffness and cognitive impairment and determine how to interfere with arterial stiffness to prevent cognitive impairment, we searched PUBMED for studies regarding the relationship between arterial stiffness and cognitive impairment that were published from 2000 to 2017. We used the following key words in our search: "arterial stiffness and cognitive impairment" and "arterial stiffness and cognitive impairment mechanism". Studies involving human subjects older than 30years were included in the review, while irrelevant studies (i.e., studies involving subjects with comorbid kidney disease, diabetes and cardiac disease) were excluded from the review. We determined that arterial stiffness severity was positively correlated with cognitive impairment. Of the markers used to assess arterial stiffness, a higher PWV, CAVI, AI, IMT and index-β and a lower ABI and FMD were related to cognitive impairment. However, the relationship between PP and cognitive impairment remained controversial. The potential mechanisms linking arterial stiffness and cognitive impairment may be associated with arterial pulsatility, as greater arterial pulsatility

  4. Stiffness of desiccating insect wings

    Energy Technology Data Exchange (ETDEWEB)

    Mengesha, T E; Vallance, R R [Department of Mechanical Engineering, The George Washington University, 738 Phillips Hall, 801 22nd St NW, Washington, DC 20052 (United States); Mittal, R, E-mail: vallance@gwu.edu [Department of Mechanical Engineering, Johns Hopkins University, 126 Latrobe Hall, 3400 N Charles Street, Baltimore, MD 21218 (United States)

    2011-03-15

    The stiffness of insect wings is typically determined through experimental measurements. Such experiments are performed on wings removed from insects. However, the wings are subject to desiccation which typically leads to an increase in their stiffness. Although this effect of desiccation is well known, a comprehensive study of the rate of change in stiffness of desiccating insect wings would be a significant aid in planning experiments as well as interpreting data from such experiments. This communication presents a comprehensive experimental analysis of the change in mass and stiffness of gradually desiccating forewings of Painted Lady butterflies (Vanessa cardui). Mass and stiffness of the forewings of five butterflies were simultaneously measured every 10 min over a 24 h period. The averaged results show that wing mass declined exponentially by 21.1% over this time period with a time constant of 9.8 h, while wing stiffness increased linearly by 46.2% at a rate of 23.4 {mu}N mm{sup -1} h{sup -1}. For the forewings of a single butterfly, the experiment was performed over a period of 1 week, and the results show that wing mass declined exponentially by 52.2% with a time constant of 30.2 h until it reached a steady-state level of 2.00 mg, while wing stiffness increased exponentially by 90.7% until it reached a steady-state level of 1.70 mN mm{sup -1}. (communication)

  5. Estimation of quasi-stiffness of the human knee in the stance phase of walking.

    Directory of Open Access Journals (Sweden)

    Kamran Shamaei

    Full Text Available Biomechanical data characterizing the quasi-stiffness of lower-limb joints during human locomotion is limited. Understanding joint stiffness is critical for evaluating gait function and designing devices such as prostheses and orthoses intended to emulate biological properties of human legs. The knee joint moment-angle relationship is approximately linear in the flexion and extension stages of stance, exhibiting nearly constant stiffnesses, known as the quasi-stiffnesses of each stage. Using a generalized inverse dynamics analysis approach, we identify the key independent variables needed to predict knee quasi-stiffness during walking, including gait speed, knee excursion, and subject height and weight. Then, based on the identified key variables, we used experimental walking data for 136 conditions (speeds of 0.75-2.63 m/s across 14 subjects to obtain best fit linear regressions for a set of general models, which were further simplified for the optimal gait speed. We found R(2 > 86% for the most general models of knee quasi-stiffnesses for the flexion and extension stages of stance. With only subject height and weight, we could predict knee quasi-stiffness for preferred walking speed with average error of 9% with only one outlier. These results provide a useful framework and foundation for selecting subject-specific stiffness for prosthetic and exoskeletal devices designed to emulate biological knee function during walking.

  6. Simvastatin Ameliorates Matrix Stiffness-Mediated Endothelial Monolayer Disruption.

    Directory of Open Access Journals (Sweden)

    Marsha C Lampi

    Full Text Available Arterial stiffening accompanies both aging and atherosclerosis, and age-related stiffening of the arterial intima increases RhoA activity and cell contractility contributing to increased endothelium permeability. Notably, statins are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA reductase inhibitors whose pleiotropic effects include disrupting small GTPase activity; therefore, we hypothesized the statin simvastatin could be used to attenuate RhoA activity and inhibit the deleterious effects of increased age-related matrix stiffness on endothelial barrier function. Using polyacrylamide gels with stiffnesses of 2.5, 5, and 10 kPa to mimic the physiological stiffness of young and aged arteries, endothelial cells were grown to confluence and treated with simvastatin. Our data indicate that RhoA and phosphorylated myosin light chain activity increase with matrix stiffness but are attenuated when treated with the statin. Increases in cell contractility, cell-cell junction size, and indirect measurements of intercellular tension that increase with matrix stiffness, and are correlated with matrix stiffness-dependent increases in monolayer permeability, also decrease with statin treatment. Furthermore, we report that simvastatin increases activated Rac1 levels that contribute to endothelial barrier enhancing cytoskeletal reorganization. Simvastatin, which is prescribed clinically due to its ability to lower cholesterol, alters the endothelial cell response to increased matrix stiffness to restore endothelial monolayer barrier function, and therefore, presents a possible therapeutic intervention to prevent atherogenesis initiated by age-related arterial stiffening.

  7. Level Classifications of Foundation Stiffness

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten

    2007-01-01

    This article describes a foundation module developed and implemented in both HAWC and FLEX capable of to simulate the frequency dependent stiffness and damping of foundations e.g. pile, gravitation and bucket foundations....

  8. Theoretical and experimental study on a compliant flipper-leg during terrestrial locomotion.

    Science.gov (United States)

    Fang, Tao; Zhou, Youcheng; Li, Shikun; Xu, Min; Liang, Haiyi; Li, Weihua; Zhang, Shiwu

    2016-08-17

    An amphibious robot with straight compliant flipper-legs can conquer various amphibious environments. The robot can rotate its flipper-legs and utilize their large deflection to walk on rough terrain, and it can oscillate the straight flipper-legs to propel itself underwater. This paper focuses on the dynamics of the compliant straight flipper-legs during terrestrial locomotion by modeling its deformation dynamically with large deflection theory and simulating it to investigate the parameters of locomotion such as trajectory, velocity, and propulsion. To validate the theoretical model of dynamic locomotion, a single-leg experimental platform is used to explore the flipper-legs in motion with various structural and kinematic parameters. Furthermore, a robotic platform mounting with four compliant flipper-legs is also developed and used to experiment with locomotion. The trajectories of the rotating axle of the compliant flipper-leg during locomotion were approximately coincidental in simulation and in experiments. The speed of locomotion and cost of transport during locomotion were explored and analyzed. The performance of different types of compliant flipper-legs during locomotion shows that varying the degrees of stiffness will have a significant effect on their locomotion. The dynamic model and analysis of the compliant flipper-leg for terrestrial locomotion facilitates the ability of amphibious robots to conquer complex environments.

  9. Evaluation of arterial stiffness in nondiabetic chronic kidney disease patients

    Directory of Open Access Journals (Sweden)

    Bodanapu Mastanvalli

    2017-01-01

    Full Text Available Chronic kidney disease (CKD is a growing problem worldwide. Clinical and epidemiologic studies have shown that structural and functional changes that occur in major arteries are a major contributing factor to the high mortality in uremic patients. Recent studies have shown a stepwise increase of the carotid-femoral pulse wave velocity (cfPWV from CKD Stage 1 to Stage 5. We evaluated the cfPWV and augmentation index (AIx, as indirect markers of arterial stiffness in patients with nondiabetic CKD and compared the values with normal population; we also evaluated the relationship between various stages of CKD and arterial stiffness markers. This cross-sectional study was carried out in the Department of Nephrology for a duration of two years from January 15, 2012, to January 14, 2014. Fifty patients with nondiabetic CKD were studied along with 50 healthy volunteers who did not have CKD, who served as controls. Assessment of arterial stiffness (blood pressure, PWV, heart rate, aortic augmentation pressure, and AIx was performed using the PeriScope device. PWV positively correlated with systolic and diastolic blood pressure, mean aortic arterial pressure, serum creatinine, and serum uric acid and negatively correlated with estimated glomerular filtration rate. Arterial stiffness increased as CKD stage increased and was higher in nondiabetic CKD group than in the general population. Arterial stiffness progressed gradually from CKD Stage 2 to 5, and then abruptly, in dialysis patients. Measures to decrease the arterial stiffness and its influence on decreasing cardiovascular events need further evaluation.

  10. The role of cable stiffness in the dynamic behaviours of submerged floating tunnel

    Directory of Open Access Journals (Sweden)

    Muhammad Naik

    2017-01-01

    Full Text Available Submerged floating tunnel (SFT is a new solution for the transportation infrastructure through sea straits, fjords, and inland waters and can be a good alternative to long span suspension bridges and immersed tunnels. The mooring cables/anchors are main structural components to provide restoring capacity to the SFT. The time domain dynamic problem of SFT moored by vertical and inclined mooring cables/anchors is formulated. The dynamic analysis of SFT subjected to hydrodynamic and seismic excitations is performed. As the cable stiffness determines the deformation ability of SFT, therefore it becomes crucial to evaluate the effect of mooring cable stiffness on the response of SFT. The displacements and internal forces of SFT clearly specify that the vertical/tension leg mooring cables provide very small stiffness as compared to inclined mooring cables. In order to keep the SFT displacements within an acceptable limit, the effect of cable stiffness should be properly evaluated for practical design of SFT.

  11. Water retention properties of stiff silt

    Directory of Open Access Journals (Sweden)

    Barbara Likar

    2017-06-01

    Full Text Available Recent research into the behaviour of soils has shown that it is in fact much more complex than can be described by the mechanics of saturated soils. Nowadays the trend of investigations has shifted towards the unsaturated state. Despite the signifiant progress that has been made so far, there are still a lot of unanswered questions related to the behaviour of unsaturated soils. For this reason, in the fild of geotechnics some new concepts are developed, which include the study of soil suction. Most research into soil suction has involved clayey and silty material, whereas up until recently no data have been available about measurements in very stiff preconsolidated sandy silt. Very stiff preconsolidated sandy silt is typical of the Krško Basin, where it is planned that some very important geotechnical structures will be built, so that knowledge about the behaviour of such soils at increased or decreased water content is essential. Several different methods can be used for soil suction measurements. In the paper the results of measurements carried out on very stiff preconsolidated sandy silt in a Bishop - Wesley double-walled triaxial cell are presented and compared with the results of soil suction measurements performed by means of a potentiometer (WP4C. All the measurement results were evaluated taking into account already known results given in the literature, using the three most commonly used mathematical models. Until now a lot of papers dealing with suction measurements in normal consolidated and preconsolidated clay have been published. Measurements on very stiff preconsolidated sandy silt, as presented in this paper were not supported before.

  12. On the effect of walking surface stiffness on inter-limb coordination in human walking: toward bilaterally informed robotic gait rehabilitation.

    Science.gov (United States)

    Skidmore, Jeffrey; Artemiadis, Panagiotis

    2016-03-22

    Robotic devices have been utilized in gait rehabilitation but have only produced moderate results when compared to conventional physiotherapy. Because bipedal walking requires neural coupling and dynamic interactions between the legs, a fundamental understanding of the sensorimotor mechanisms of inter-leg coordination during walking, which are not well understood but are systematically explored in this study, is needed to inform robotic interventions in gait therapy. In this study we investigate mechanisms of inter-leg coordination by utilizing novel sensory perturbations created by real-time control of floor stiffness on a split-belt treadmill. We systematically alter the unilateral magnitude of the walking surface stiffness and the timing of these perturbations within the stance phase of the gait cycle, along with the level of body-weight support, while recording the kinematic and muscular response of the uperturbed leg. This provides new insight into the role of walking surface stiffness in inter-leg coordination during human walking. Both paired and unpaired unadjusted t-tests at the 95 % confidence level are used in the approriate scernario to determine statistical significance of the results. We present results of increased hip, knee, and ankle flexion, as well as increased tibialis anterior and soleus activation, in the unperturbed leg of healthy subjects that is repeatable and scalable with walking surface stiffness. The observed response was not impacted by the level of body-weight support provided, which suggests that walking surface stiffness is a unique stimulus in gait. In addition, we show that the activation of the tibialis anterior and soleus muscles is altered by the timing of the perturbations within the gait cycle. This paper characterizes the contralateral leg's response to ipsilateral manipulations of the walking surface and establishes the importance of walking surface stiffness in inter-leg coordination during human walking.

  13. Scaling of the spring in the leg during bouncing gaits of mammals.

    Science.gov (United States)

    Lee, David V; Isaacs, Michael R; Higgins, Trevor E; Biewener, Andrew A; McGowan, Craig P

    2014-12-01

    Trotting, bipedal running, and especially hopping have long been considered the principal bouncing gaits of legged animals. We use the radial-leg spring constant [Formula: see text] to quantify the stiffness of the physical leg during bouncing gaits. The radial-leg is modeled as an extensible strut between the hip and the ground and [Formula: see text] is determined from the force and deflection of this strut in each instance of stance. A Hookean spring is modeled in-series with a linear actuator and the stiffness of this spring [Formula: see text] is determined by minimizing the work of the actuator while reproducing the measured force-deflection dynamics of an individual leg during trotting or running, and of the paired legs during hopping. Prior studies have estimated leg stiffness using [Formula: see text], a metric that imagines a virtual-leg connected to the center of mass. While [Formula: see text] has been applied extensively in human and comparative biomechanics, we show that [Formula: see text] more accurately models the spring in the leg when actuation is allowed, as is the case in biological and robotic systems. Our allometric analysis of [Formula: see text] in the kangaroo rat, tammar wallaby, dog, goat, and human during hopping, trotting, or running show that [Formula: see text] scales as body mass to the two-third power, which is consistent with the predictions of dynamic similarity and with the scaling of [Formula: see text]. Hence, two-third scaling of locomotor spring constants among mammals is supported by both the radial-leg and virtual-leg models, yet the scaling of [Formula: see text] emerges from work-minimization in the radial-leg model instead of being a defacto result of the ratio of force to length used to compute [Formula: see text]. Another key distinction between the virtual-leg and radial-leg is that [Formula: see text] is substantially greater than [Formula: see text], as indicated by a 30-37% greater scaling coefficient for [Formula

  14. Biomaterial stiffness determines stem cell fate.

    Science.gov (United States)

    Lv, Hongwei; Wang, Heping; Zhang, Zhijun; Yang, Wang; Liu, Wenbin; Li, Yulin; Li, Lisha

    2017-06-01

    Stem cells have potential to develop into numerous cell types, thus they are good cell source for tissue engineering. As an external physical signal, material stiffness is capable of regulating stem cell fate. Biomaterial stiffness is an important parameter in tissue engineering. We summarize main measurements of material stiffness under different condition, then list and compare three main methods of controlling stiffness (material amount, crosslinking density and photopolymeriztion time) which interplay with one another and correlate with stiffness positively, and current advances in effects of biomaterial stiffness on stem cell fate. We discuss the unsolved problems and future directions of biomaterial stiffness in tissue engineering. Copyright © 2017. Published by Elsevier Inc.

  15. ORTHOPEDIC LEG BRACE

    Science.gov (United States)

    Myers, William Neil (Inventor)

    2005-01-01

    Knee braces generally have been rigid in both the knee bending direction and in the knee straightening direction unless a manually operated release is incorporated in them to allow the knee to bend. Desirably a braced knee joint should effectively duplicate the compound, complex, actions of a normal knee. The key to knee braces is the knee joint housing. The housing herein carries a number of cam action pawls. with teeth adapted to engage the internal teeth of a ratchet ring mounted in the housing. Cam action return springs and the shape of the cam action pawl teeth allow rotation of the ratchet ring in a leg straightening direction while still supporting a load. The leg can then be extended during walking while at the same time being prevented by the cam action pawls from buckling in the knee bending direction.

  16. Model-Based Experimental Development of Passive Compliant Robot Legs from Fiberglass Composites

    OpenAIRE

    Lin, Shang-Chang; Hu, Chia-Jui; Shih, Wen-Pin; Lin, Pei-Chun

    2015-01-01

    We report on the methodology of developing compliant, half-circular, and composite robot legs with designable stiffness. First, force-displacement experiments on flat cantilever composites made by one or multifiberglass cloths are executed. By mapping the cantilever mechanics to the virtual spring model, the equivalent elastic ...

  17. Legāti

    OpenAIRE

    Segliņa, Aiga

    2010-01-01

    Autore teorētiski analizē legāta jēdzienu testamentārās mantošanas ietvaros un atspoguļo praktiska pētījuma rezultātus. Teorētiskā daļa apskata legāta nodibināšanas formu un spēkā esamību, tā iegūšanu un atraidīšanu, izpildi un zaudēšanu, novēlējuma robežas un aprobežojumus. Pētījums veikts aptaujas veidā ar mērķi noskaidrot, cik liela Latvijas iedzīvotāju daļa apzinās legāta nodrošinātās priekšrocības testamentārajā mantošanā. Apskatīts notāra neitralitātes jautājums attiecībā pret mantošana...

  18. Stable walking with asymmetric legs

    International Nuclear Information System (INIS)

    Merker, Andreas; Rummel, Juergen; Seyfarth, Andre

    2011-01-01

    Asymmetric leg function is often an undesired side-effect in artificial legged systems and may reflect functional deficits or variations in the mechanical construction. It can also be found in legged locomotion in humans and animals such as after an accident or in specific gait patterns. So far, it is not clear to what extent differences in the leg function of contralateral limbs can be tolerated during walking or running. Here, we address this issue using a bipedal spring-mass model for simulating walking with compliant legs. With the help of the model, we show that considerable differences between contralateral legs can be tolerated and may even provide advantages to the robustness of the system dynamics. A better understanding of the mechanisms and potential benefits of asymmetric leg operation may help to guide the development of artificial limbs or the design novel therapeutic concepts and rehabilitation strategies.

  19. Research regarding stiffness optimization of wires used for joints actuation from an elephant's trunk robotic arm

    Science.gov (United States)

    Ciofu, C.; Stan, G.

    2016-11-01

    Elephant's trunk robotic arms driven by wires and pulley mechanisms have issues with wires stiffness because of the entailed elastic deformations that is causing errors of positioning. Static and dynamic loads from each joint of the robotic arm affect the stiffness of driving wires and precision positioning. The influence of wires elastic deformation on precision positioning decreases with the increasing of wires stiffness by using different pre-tensioning devices. In this paper, we analyze the variation of driving wires stiffness particularly to each wire driven joint. We obtain optimum wires stiffness variation by using an analytical method that highlights the efficiency of pre-tensioning mechanism. The analysis of driving wires stiffness is necessary for taking appropriate optimization measures of robotic arm dynamic behavior and, thus, for decreasing positioning errors of the elephant's trunk robotic arm with inner actuation through wires/cables.

  20. HIV infection and aortic stiffness.

    Science.gov (United States)

    Leite, Luisa Helena Maia; Cohen, Ariel; Boccara, Franck

    People living with human immunodeficiency virus (HIV) infection and receiving antiretroviral therapy now have the same life expectancy as the general population. However, they have a higher risk of atherosclerotic cardiovascular events because of a complex and polyfactorial vasculopathy, combining the effects of antiretroviral therapy, the HIV virus itself, immune activation, chronic inflammation and metabolic disturbances. Whether people living with HIV infection experience increased vascular aging compared with the general population remains controversial. To summarize current knowledge of the association between HIV infection and aortic stiffness as a marker of vascular aging. This review included 18 clinical studies in adult populations, published between 2009 and 2016, and identified on PubMed/MEDLINE or other databases. Search terms were aortic stiffness, arterial stiffness, vascular aging, pulse wave velocity and HIV. All 18 studies were observational, and compared groups infected (HIV+) and not infected (HIV-) with HIV. Ten studies (55%) reported no significant differences in aortic stiffness between HIV+ groups and age-matched HIV- control groups. The main reported determinants of aortic stiffness were age, blood pressure, smoking, metabolic syndrome and HIV-related variables, including CD4/CD8 ratio, current T-CD4 count CD4+ count < 200/mm 3 . We found discordant results regarding whether HIV+ patients had increased aortic stiffness compared with HIV- controls. However, HIV-related conditions were associated with vascular health. This association has been confirmed in recent prospective studies. There is emerging evidence that HIV itself and immune activity affect vascular health and the large arteries. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  1. A Portable Stiffness Measurement System

    Directory of Open Access Journals (Sweden)

    Onejae Sul

    2017-11-01

    Full Text Available A new stiffness measurement method is proposed that utilizes the lateral deformation profile of an object under indentation. The system consists of a force measurement module between a pair of equidistant touch sensing modules. Unique feature of the method is that by adjusting the touch module separation, indenter protrusion, and spring constant of the force sensing module, one can choose a desired sensing range for the force module. This feature helps to enhance the stiffness differentiation between objects of similar hardness and avoids measurement saturation. We devised a portable measurement system based on the method, and tested its performance with several materials including polymer foams and human skin.

  2. Dynamic stiffness of suction caissons

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten; Andersen, Lars

    This report concerns the dynamic soil-structure interaction of steel suction caissons applied as foundations for offshore wind turbines. An emphasis is put on torsional vibrations and coupled sliding/rocking motion, and the influence of the foundation geometry and the properties of the surrounding...... soil is examined. The soil is simplified as a homogenous linear viscoelastic material and the dynamic stiffness of the suction caisson is expressed in terms of dimensionless frequency-dependent coefficients corresponding to the different degrees of freedom. The dynamic stiffness coefficients...

  3. Short-interval leg movements during sleep entail greater cardiac activation than periodic leg movements during sleep in restless legs syndrome patients.

    Science.gov (United States)

    Ferri, Raffaele; Rundo, Francesco; Silvani, Alessandro; Zucconi, Marco; Aricò, Debora; Bruni, Oliviero; Lanuzza, Bartolo; Ferini-Strambi, Luigi; Manconi, Mauro

    2017-10-01

    Periodic leg movements during sleep (PLMS) are sequences of ≥4 motor events with intermovement intervals (IMI) of 10-90 s. PLMS are a supportive diagnostic criterion for restless legs syndrome (RLS) and entail cardiac activation, particularly when associated with arousal. RLS patients also over-express short-interval leg movements during sleep (SILMS), which have IMI leg movements. We found that the duration of the R-R interval decrease with SILMS doublets was significantly longer than that with PLMS, whereas the maximal decrease in R-R interval was similar. Scoring SILMS in RLS patients may therefore be relevant from a cardiac autonomic perspective. © 2017 European Sleep Research Society.

  4. Stiff muscle fibers in calf muscles of patients with cerebral palsy lead to high passive muscle stiffness.

    Science.gov (United States)

    Mathewson, Margie A; Chambers, Henry G; Girard, Paul J; Tenenhaus, Mayer; Schwartz, Alexandra K; Lieber, Richard L

    2014-12-01

    Cerebral palsy (CP), caused by an injury to the developing brain, can lead to alterations in muscle function. Subsequently, increased muscle stiffness and decreased joint range of motion are often seen in patients with CP. We examined mechanical and biochemical properties of the gastrocnemius and soleus muscles, which are involved in equinus muscle contracture. Passive mechanical testing of single muscle fibers from gastrocnemius and soleus muscle of patients with CP undergoing surgery for equinus deformity showed a significant increase in fiber stiffness (p<0.01). Bundles of fibers that included their surrounding connective tissues showed no stiffness difference (p=0.28).). When in vivo sarcomere lengths were measured and fiber and bundle stiffness compared at these lengths, both fibers and bundles of patients with CP were predicted to be much stiffer in vivo compared to typically developing (TD) individuals. Interestingly, differences in fiber and bundle stiffness were not explained by typical biochemical measures such as titin molecular weight (a giant protein thought to impact fiber stiffness) or collagen content (a proxy for extracellular matrix amount). We suggest that the passive mechanical properties of fibers and bundles are thus poorly understood. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  5. Association of Gastrocnemius Muscle Stiffness With Passive Ankle Joint Stiffness and Sex-Related Difference in the Joint Stiffness.

    Science.gov (United States)

    Chino, Kintaro; Takashi, Hideyuki

    2017-11-15

    Passive ankle joint stiffness is affected by all structures located within and over the joint, and is greater in men than in women. Localized muscle stiffness can be assessed by ultrasound shear wave elastography, and muscle architecture such as fascicle length and pennation angle can be measured by B-mode ultrasonography. Thus, we assessed localized muscle stiffness of the medial gastrocnemius (MG) with consideration of individual variability in the muscle architecture, and examined the association of the muscle stiffness with passive ankle joint stiffness and the sex-related difference in the joint stiffness. Localized muscle stiffness of the MG in 16 men and 17 women was assessed at 10° and 20° plantar flexion, neutral anatomical position, 10° and 20° dorsiflexion. Fascicle length and pennation angle of the MG were measured at these joint positions. Passive ankle joint stiffness was determined by the ankle joint angle-torque relationship. Localized MG muscle stiffness was not significantly correlated with passive ankle joint stiffness, and did not show significant sex-related difference, even when considering the muscle architecture. This finding suggest that muscle stiffness of the MG would not be a prominent factor to determine passive ankle joint stiffness and the sex-related difference in the joint stiffness.

  6. Leg cramps and restless legs syndrome during pregnancy.

    Science.gov (United States)

    Hensley, Jennifer G

    2009-01-01

    Sleep disturbance during pregnancy can result in excessive daytime sleepiness, diminished daytime performance, inability to concentrate, irritability, and the potential for an increased length of labor and increased risk of operative birth. Sleep disturbance may be the result of a sleep disorder, such as leg cramps, a common yet benign disorder, or restless legs syndrome, a sensorimotor disorder. Both disrupt sleep, are distressing to the pregnant woman, and mimic one another and other serious disorders. During pregnancy, up to 30% of women can be affected by leg cramps, and up to 26% can be affected by restless legs syndrome.

  7. [Swollen leg with blisters].

    Science.gov (United States)

    Rafeiner, Ph; Templeton, A J; Vonesch, H J

    2005-10-05

    We report the case of a 84-year-old woman suffering from strong pain in her right leg initially resembling thrombosis of deep veins. Eight hours after admission a superficial blister developed at the calf with following hemorrhagic aspect and spontanous eruption of clear yellowish fluid. Later on a new blister appeared at the thigh. The patient died 33 hours after admission of streptococcal toxic shock syndrome. The latter was based on a necrotizing fasciitis. Streptoccus pyogenes (group A) could be cultivated from the blood and fluid of the blister. We discuss the clinical presentation of necrotizing fasciitis with "pain out of proportion" as characteristic complaint and the appropriate management.

  8. Textiloma in the leg

    Directory of Open Access Journals (Sweden)

    Patel Amol

    2007-01-01

    Full Text Available Textiloma is defined as a tumor formed due to retained gauze. It is rarely reported in the musculoskeletal system. We are presenting a case with a soft tissue swelling over the lateral aspect of the lower third of the leg, come for implant removal of the distal tibia and fibular fracture. We removed the soft tissue mass enbloc thinking it to be a benign tumor. On cutting the mass on the operation table, a gauze piece encased by fibrous tissue was found. Textiloma can present as tumoral forms and can mimic as a pseudo-tumor.

  9. MEMS measurements of single cell stiffness decay due to cyclic mechanical loading.

    Science.gov (United States)

    Barazani, Bruno; Warnat, Stephan; MacIntosh, Andrew J; Hubbard, Ted

    2017-08-25

    The goal of this study was to measure the mechanical stiffness of individual cells and to observe changes due to the application of repeated cell mechanical loads. 28 single baker's yeast cells (Saccharomyces cerevisiae) were fatigue tested and had their stiffness measured during repetitive loading cycles performed by a MEMS squeezer in aqueous media. Electrothermal micro-actuators compressed individual cells against a reference back spring; cell and spring motions were measured using a FFT image analysis technique with ~10 nm resolution. Cell stiffness was calculated based on measurements of cell elongation vs. applied force which resulted in stiffness values in the 2-10 N/m range. The effect of increased force was studied for cells mechanically cycled 37 times. Cell stiffness decreased as the force and the cycle number increased. After 37 loading cycles (~4 min), forces of 0.24, 0.29, 0.31, and 0.33 μN caused stiffness drops of 5%, 13%, 31% and 41% respectively. Cells force was then set to 0.29 μN and cells were tested over longer runs of 118 and 268 cycles. After 118 cycles (~12 min) cells experienced an average stiffness drop of 68%. After 268 cycles (~25 min) cells had a stiffness drop of 77%, and appeared to reach a stiffness plateau of 20-25% of the initial stiffness after approximately 200 cycles.

  10. Test of Gravel to South Leg - Siri Platform

    DEFF Research Database (Denmark)

    Thomassen, Kristina; Ibsen, Lars Bo

    A grout connection between one of the legs of the offshore platform, Siri, and a water caisson at the seabed is failed. The failure leaves a gap in the grout connection meaning that the stiffness of the connection is disappeared resulting in movements of the platform. These movements cause cracks...... in the caisson, hence, the stiffness of the connection must be re-established. In this report the effect of filling a sand material into the gap in the grout connection is investigated. Four types of sand materials is tested; Sand 0-8 mm, Norit 0-2 mm, Norit 0-5 mm, and Sand 0.4-5.6 mm. The comparison...

  11. [From stiff man syndrome to stiff person spectrum disorders].

    Science.gov (United States)

    Meinck, H-M; Balint, B

    2018-02-01

    The identification of new variants of the stiff man syndrome (SMS) and of new, probably pathogenic neuronal autoantibodies has led to the concept of stiff man (or person) spectrum disorders (SPSD). This is an expanding group of rare chronic autoimmune inflammatory diseases of the central nervous system (CNS) that have in common the main symptoms of fluctuating rigidity and spasms with pronounced stimulus sensitivity. These core symptoms are mandatory and can be accompanied by a wide variety of other neurological signs. The SPSDs are associated with autoantibodies directed against neuronal proteins that attenuate excitability. Neither clinical phenotypes nor the course of SPSD correlate closely with the antibody status. The treatment of these diseases aims at maintaining mobility and is pragmatically oriented to the degree of impediment and comprises antispastic, anticonvulsant and immunomodulating or immunosuppressive medication strategies.

  12. Differentiating nocturnal leg cramps and restless legs syndrome.

    Science.gov (United States)

    Rana, Abdul Qayyum; Khan, Fatima; Mosabbir, Abdullah; Ondo, William

    2014-07-01

    Leg pain and discomfort are common complaints in any primary physician's clinic. Two common causes of pain or discomfort in legs are nocturnal leg cramps (NLC) and restless leg syndrome (RLS). NLC present as painful and sudden contractions mostly in part of the calf. Diagnosis of NLC is mainly clinical and sometimes involves investigations to rule out other mimics. RLS is a condition characterized by the discomfort or urge to move the lower limbs, which occurs at rest or in the evening/night. The similarity of RLS and leg cramps poses the issue of errors in diagnosing and differentiating the two. In this paper we review the pathopysiology of each entity and their diagnosis as well as treatment. The two conditions are then compared to appreciate the differences and similarities. Finally, suggestions are recommended for complete assessment.

  13. Weight reduction and aortic stiffness in obese children and adolescents

    DEFF Research Database (Denmark)

    Hvidt, K. N.; Olsen, M. H.; Ibsen, H.

    2015-01-01

    Little is known about the effect of weight reduction on aortic stiffness and especially so in the young. The present study investigates whether weight reduction influences aortic stiffness in obese children and adolescents. Carotid-femoral pulse wave velocity (cfPWV) and augmentation index at heart...... rate 75 (AIx@HR75) were measured in 72 obese patients aged 10-18 years at baseline and after 1-year of lifestyle intervention (follow-up). We found that although the degree of obesity decreased (Delta body mass index z-score: -0.24 +/- 0.45, P ....27 +/- 0.47 ms(-1), P obesity measures. No significant change...

  14. Shoulder Stiffness : Current Concepts and Concerns

    NARCIS (Netherlands)

    Itoi, Eiji; Arce, Guillermo; Bain, Gregory I.; Diercks, Ronald L.; Guttmann, Dan; Imhoff, Andreas B.; Mazzocca, Augustus D.; Sugaya, Hiroyuki; Yoo, Yon-Sik

    Shoulder stiffness can be caused by various etiologies such as immobilization, trauma, or surgical interventions. The Upper Extremity Committee of ISAKOS defined the term "frozen shoulder" as idiopathic stiff shoulder, that is, without a known cause. Secondary stiff shoulder is a term that should be

  15. The study of stiffness modulus values for AC-WC pavement

    Science.gov (United States)

    Lubis, AS; Muis, Z. A.; Iskandar, T. D.

    2018-02-01

    One of the parameters of the asphalt mixture in order for the strength and durability to be achieved as required is the stress-and-strain showing the stiffness of a material. Stiffness modulus is a very necessary factor that will affect the performance of asphalt pavements. If the stiffness modulus value decreases there will be a cause of aging asphalt pavement crack easily when receiving a heavy load. The high stiffness modulus asphalt concrete causes more stiff and resistant to bending. The stiffness modulus value of an asphalt mixture material can be obtained from the theoretical (indirect methods) and laboratory test results (direct methods). For the indirect methods used Brown & Brunton method, and Shell Bitumen method; while for the direct methods used the UMATTA tool. This study aims to determine stiffness modulus values for AC-WC pavement. The tests were conducted in laboratory that used 3 methods, i.e. Brown & Brunton Method, Shell Bitumen Method and Marshall Test as a substitute tool for the UMATTA tool. Hotmix asphalt made from type AC-WC with pen 60/70 using a mixture of optimum bitumen content was 5.84% with a standard temperature variation was 60°C and several variations of temperature that were 30, 40, 50, 70 and 80°C. The stiffness modulus value results obtained from Brown & Brunton Method, Shell Bitumen Method and Marshall Test which were 1374,93 Mpa, 235,45 Mpa dan 254,96 Mpa. The stiffness modulus value decreases with increasing temperature of the concrete asphalt. The stiffness modulus value from the Bitumen Shell method and the Marshall Test has a relatively similar value.The stiffness modulus value from the Brown & Brunton method is greater than the Bitumen Shell method and the Marshall Test, but can not measure the stiffness modulus value at temperature above 80°C.

  16. Randomized Comparison of the Therapeutic Effect of Acupuncture, Massage, and Tachibana-Style-Method on Stiff Shoulders by Measuring Muscle Firmness, VAS, Pulse, and Blood Pressure

    Directory of Open Access Journals (Sweden)

    Kazuhiro Tachibana

    2012-01-01

    Full Text Available To compare the therapeutic efficacy of acupuncture, massage, and Tachibana-Ryojutsu (one of Japanese traditional body balance therapy techniques (SEITAI, on stiff shoulders, the subjects’ muscle firmness, blood pressure, pulse, VAS, and body temperature were measured before and after the treatment. Forty-seven volunteer subjects gave written informed consent to participate in this study. The subjects were randomly divided into three groups to receive acupuncture, massage, or Tachibana-Ryojutsu. Each therapy lasted for 90 seconds. The acupuncture treatment was applied by a retaining-needle at GB-21, massage was conducted softly on the shoulders, and Tachibana-Ryojutsu treated only the muscles and joints from the legs to buttocks without touching the shoulders or backs. The study indicated that the muscle firmness and VAS of the Tachibana-Ryojutsu group decreased significantly in comparison with the acupuncture and massage groups after treatment.

  17. Klinefelter Syndrome With Leg Ulcers

    Directory of Open Access Journals (Sweden)

    Narendra G

    1999-01-01

    Full Text Available Leg ulcers are frequently caused by venous insufficiency, arterial insufficiency, neuropathy, or a combination of these factors. Klinefelter syndrome in association with chronic leg ulcers have been reported earlier. We report a case of Klinefelter syndrome with non- healing ulcer. The diagnosis of the Klinefelter syndrome was confirmed by karyotyping.

  18. Fault shear stiffness as the key parameter determining fault behavior

    Science.gov (United States)

    Ostapchuk, A. A.; Kocharyan, G. G.; Pavlov, D. V.; Kabychenko, N. V.

    2017-12-01

    Presented are the results of laboratory experiments on studying the variation of fault shear stiffness during a seismic cycle. It is shown that the slip mode correlates well with the specific value of fault stiffness ks1 at the loading stage. As the fault goes over to a metastable state, its stiffness changes abruptly from ks1 to 0. This change can be detected in active monitoring, which consists in analyzing the frequency response of an oscillatory "block-fault" system. A periodic pulsed action on the "block-fault" system allowed us to reliably detect a relative decrease by 30% of the resonance frequency of its response when the system goes over to the metastable state.

  19. Evaluating pulp stiffness from fibre bundles by ultrasound

    Science.gov (United States)

    Karppinen, Timo; Montonen, Risto; Määttänen, Marjo; Ekman, Axel; Myllys, Markko; Timonen, Jussi; Hæggström, Edward

    2012-06-01

    A non-destructive ultrasonic tester was developed to measure the stiffness of pulp bundles. The mechanical properties of pulp are important when estimating the behaviour of paper under stress. Currently available pulp tests are tedious and alter the fibres structurally and mechanically. The developed tester employs (933 ± 15) kHz tweezer-like ultrasonic transducers and time-of-flight measurement through (9.0 ± 2.5) mm long and (0.8 ± 0.1) mm thick fibre bundles kept at (19.1 ± 0.4) °C and (62 ± 1)% RH. We determined the stiffness of soft wood pulps produced by three kraft pulping modifications: standard kraft pulp, (5.2 ± 0.4) GPa, prehydrolysis kraft pulp, (4.3 ± 0.4) GPa, and alkali extracted prehydrolysis kraft pulp, (3.3 ± 0.4) GPa. Prehydrolysis and alkali extraction processes mainly lowered the hemicellulose content of the pulps, which essentially decreased the fibre-wall stiffness hence impairing the stiffness of the fibre networks. Our results indicate that the method allows ranking of pulps according to their stiffness determined from bundle-like samples taken at an early phase of the papermaking process.

  20. [Metabolic syndrome and aortic stiffness].

    Science.gov (United States)

    Simková, A; Bulas, J; Murín, J; Kozlíková, K; Janiga, I

    2010-09-01

    The metabolic syndrome (MS) is a cluster of risk factors that move the patient into higher level of risk category of cardiovascular disease and the probability of type 2 diabetes mellitus manifestation. Definition of MS is s based on the presence of selected risk factors as: abdominal obesity (lager waist circumpherence), atherogenic dyslipidemia (low value of HDL-cholesterol and increased level of triglycerides), increased fasting blood glucose (or type 2 DM diagnosis), higher blood pressure or antihypertensive therapy. In 2009 there were created harmonizing criteria for MS definition; the condition for assignment of MS is the presence of any 3 criteria of 5 mentioned above. The underlying disorder of MS is an insulin resistance or prediabetes. The patients with MS more frequently have subclinical (preclinical) target organ disease (TOD) which is the early sings of atherosclerosis. Increased aortic stiffness is one of the preclinical diseases and is defined by pathologically increased carotidofemoral pulse wave velocity in aorta (PWV Ao). With the aim to assess the influence of MS on aortic stiffness we examined the group of women with arterial hypertension and MS and compare them with the group of women without MS. The aortic stiffness was examined by Arteriograph--Tensiomed, the equipment working on the oscillometric principle in detection of pulsations of brachial artery. This method determines the global aortic stiffness based on the analysis of the shape of pulse curve of brachial artery. From the cohort of 49 pts 31 had MS, the subgroups did not differ in age or blood pressure level. The mean number of risk factors per person in MS was 3.7 comparing with 1.7 in those without MS. In the MS group there was more frequently abdominal obesity present (87% vs 44%), increased fasting blood glucose (81% vs 22%) and low HDL-cholesterol level. The pulse wave velocity in aorta, PWV Ao, was significantly higher in patients with MS (mean value 10,19 m/s vs 8,96 m

  1. Acute exercise modifies titin phosphorylation and increases cardiac myofilament stiffness

    Directory of Open Access Journals (Sweden)

    Anna Eliane Müller

    2014-11-01

    Full Text Available Titin-based myofilament stiffness is largely modulated by phosphorylation of its elastic I-band regions N2-Bus (decreases passive stiffness, PT and PEVK (increases PT. Here, we tested the hypothesis that acute exercise changes titin phosphorylation and modifies myofilament stiffness. Adult rats were exercised on a treadmill for 15min, untrained animals served as controls. Titin phosphorylation was determined by Western blot analysis using phosphospecific antibodies to Ser4099 and Ser4010 in the N2-Bus region (PKG and PKA-dependent. respectively, and to Ser11878 and Ser 12022 in the PEVK region (PKCα and CaMKIIδ-dependent, respectively. Passive tension was determined by step-wise stretching of isolated skinned cardiomyocytes to sarcomere length ranging from 1.9-2.4µm and showed a significantly increased PT from exercised samples, compared to controls. In cardiac samples titin N2-Bus phosphorylation was significantly decreased by 40% at Ser4099, however, no significant changes were observed at Ser4010. PEVK phosphorylation at Ser11878 was significantly increased, which is probably mediated by the observed exercise-induced increase in PKCα activity. Interestingly, relative phosphorylation of Ser12022 was substantially decreased in the exercised samples. Surprisingly, in skeletal samples from acutely exercised animals we detected a significant decrease in PEVK phosphorylation at Ser11878 and an increase in Ser12022 phosphorylation; however, PKCα activity remained unchanged. In summary, our data show that a single exercise bout of 15 min affects titin domain phosphorylation and titin-based myocyte stiffness with obviously divergent effects in cardiac and skeletal muscle tissues. The observed changes in titin stiffness could play an important role in adapting the passive and active properties of the myocardium and the skeletal muscle to increased physical activity.

  2. Actigraphic assessment of periodic leg movements in patients with restless legs syndrome.

    Science.gov (United States)

    Cippà, Maria A T; Baumann, Christian R; Siccoli, Massimiliano M; Bassetti, Claudio L; Poryazova, Rositsa; Werth, Esther

    2013-10-01

    The diagnosis of restless legs syndrome (RLS) relies upon diagnostic criteria which are based on history only, and dopaminergic treatment is not normally the first choice of treatment for all patients. It would be worthwhile to identify patients non-responsive to dopaminergic treatment beforehand, because they may suffer from a restless legs-like syndrome and may require alternative treatment. We included retrospectively 24 adult patients fulfilling the four essential criteria for restless legs and 12 age-matched healthy controls. They were investigated by ambulatory actigraphy from both legs over three nights, and patients started treatment with dopamine agonists after this diagnostic work-up. We examined 12 responders to dopaminergic treatment and 12 non-responders and studied the association between response to dopaminergic treatment and the periodic limb movement index (PLMI) as assessed with actigraphy. Demographic characteristics, excessive daytime sleepiness and fatigue at baseline were similar in all three groups. Baseline RLS severity was similar between responders and non-responders [International Restless Legs Severity Scale (IRLS): 25 ± 9 and 24 ± 8]. Group comparisons of PLMI before treatment initiation showed significant differences between the three groups. Post-hoc pairwise comparisons revealed that healthy controls had significantly lower PLMI (4.9 ± 4.5) than responders (29.3 ± 22.7) and non-responders (13.3 ± 11.2). Similarly, the PLMI in responders was lower than in non-responders. PLMI day-to-day variability did not differ between responders and non-responders and there was no correlation between treatment effect, as assessed by the decrease of the IRLS and baseline PLMI. Our retrospective study indicates that actigraphy to assess periodic limb movements may contribute to a better diagnosis of dopamine-responsive restless legs syndrome. © 2013 European Sleep Research Society.

  3. Effect of exercise on arterial stiffness

    DEFF Research Database (Denmark)

    Montero, David; Breenfeldt Andersen, Andreas; Oberholzer, Laura

    2017-01-01

    BACKGROUND: Whether arterial stiffness (AS) can be improved by regular exercise in healthy individuals remains equivocal according to cross-sectional and longitudinal studies assessing arterial properties at discrete time points. The purpose of the present study was to pinpoint the time course......), in 9 previously untrained healthy normotensive adults (27 ± 4 years) with no history of cardiovascular disease. Exercise capacity was assessed by maximal oxygen consumption (VO2max) elicited by incremental ergometry. RESULTS: VO2max increased throughout the ET intervention (+12% from week 0 to week 8...... points (P = 0.196) although a linear decreasing trend was detected (P = 0.016). CONCLUSIONS: Central AS augments during a conventional ET intervention that effectively enhances aerobic exercise capacity in young individuals. This suggests that normal, healthy elastic arteries are not amendable...

  4. Decreased Libido

    Science.gov (United States)

    ... causes decreased libido? Decreased libido often accompanies other sexual disorders. Although most men with erectile dysfunction do not complain of decreased libido, after time, persistent failure with erections and sexual performance can lead to reduced sex drive in ...

  5. Mechanical Impedance of the non-loaded Lower Leg with Relaxed Muscles in the Transverse Plane

    Directory of Open Access Journals (Sweden)

    Evandro Maicon Ficanha

    2015-12-01

    Full Text Available This paper describes the protocols and results of the experiments for the estimation of the mechanical impedance of the humans’ lower leg in the External-Internal (EI direction in the transverse plane under non-load bearing condition and with relaxed muscles. The objectives of the estimation of the lower leg’s mechanical impedance are to facilitate the design of passive and active prostheses with mechanical characteristics similar to the humans’ lower leg, and to define a reference that can be compared to the values from the patients suffering from spasticity. The experiments were performed with 10 unimpaired male subjects using a lower extremity rehabilitation robot (Anklebot, Interactive Motion Technologies, Inc. capable of applying torque perturbations to the foot. The subjects were in a seated position, and the Anklebot recorded the applied torques and the resulting angular movement of the lower leg. In this configuration, the recorded dynamics are due mainly to the rotations of the ankle’s talocrural and the subtalar joints, and any contribution of the tibiofibular joints and knee joint. The dynamic mechanical impedance of the lower leg was estimated in the frequency domain with an average coherence of 0.92 within the frequency range of 0 to 30Hz, showing a linear correlation between the displacement and the torques within this frequency range under the conditions of the experiment. The mean magnitude of the quasi-static stiffness of the lower leg (the impedance magnitude averaged in the range of 0-1 Hz was determined as 4.9±0.74 Nm/rad. The direct estimation of the quasi-static stiffness of the lower leg results in the mean value of 5.8±0.81 Nm/rad. An analysis of variance (ANOVA shows that the estimated values for the quasi-static stiffness from the two experiments are not statistically different.

  6. Stiffness of skinned rabbit psoas fibers in MgATP and MgPPi solution.

    Science.gov (United States)

    Brenner, B; Chalovich, J M; Greene, L E; Eisenberg, E; Schoenberg, M

    1986-10-01

    The stiffness of single skinned rabbit psoas fibers was measured during rapid length changes applied to one end of the fibers. Apparent fiber stiffness was taken as the initial slope when force was plotted vs. change in sarcomere length. In the presence of MgATP, apparent fiber stiffness increased with increasing speed of stretch. With the fastest possible stretches, the stiffness of relaxed fibers at an ionic strength of 20 mM reached more than 50% of the stiffness measured in rigor. However, it was not clear whether apparent fiber stiffness had reached a maximum, speed independent value. The same behavior was seen at several ionic strengths, with increasing ionic strength leading to a decrease in the apparent fiber stiffness measured at any speed of stretch. A speed dependence of apparent fiber stiffness was demonstrated even more clearly when stiffness was measured in the presence of 4 mM MgPPi. In this case, stiffness varied with speed of stretch over about four decades. This speed dependence of apparent fiber stiffness is likely due to cross-bridges detaching and reattaching during the stiffness measurement (Schoenberg, 1985. Biophys. J. 48:467). This means that obtaining an estimate of the maximum number of cross-bridges attached to actin in relaxed fibers at various ionic strengths is not straightforward. However, the data we have obtained are consistent with other estimates of cross-bridge affinity for actin in fibers (Brenner et al., 1986. Biophys. J. In press.) which suggest that ~60-90% of the cross-bridges attached in rigor are attached in relaxed fibers at an ionic strength of 20 mM and ~2-10% of this number of cross-bridges are attached in a relaxed fiber at an ionic strength of 170 mM.

  7. Multi-pulse chaotic motions of a rotor-active magnetic bearing system with time-varying stiffness

    International Nuclear Information System (INIS)

    Zhang, W.; Yao, M.H.; Zhan, X.P.

    2006-01-01

    In this paper, we investigate the Shilnikov type multi-pulse chaotic dynamics for a rotor-active magnetic bearings (AMB) system with 8-pole legs and the time-varying stiffness. The stiffness in the AMB is considered as the time-varying in a periodic form. The dimensionless equation of motion for the rotor-AMB system with the time-varying stiffness in the horizontal and vertical directions is a two-degree-of-freedom nonlinear system with quadratic and cubic nonlinearities and parametric excitation. The asymptotic perturbation method is used to obtain the averaged equations in the case of primary parametric resonance and 1/2 subharmonic resonance. It is found from the numerical results that there are the phenomena of the Shilnikov type multi-pulse chaotic motions for the rotor-AMB system. A new jumping phenomenon is discovered in the rotor-AMB system with the time-varying stiffness

  8. Restless legs syndrome

    Directory of Open Access Journals (Sweden)

    Ovallath S

    2012-10-01

    Full Text Available Sujith Ovallath, P DeepaJames Parkinson's Movement Disorder Research Centre, Kannur Medical College, Kerala, IndiaBackground: Restless legs syndrome (RLS is a common sleep-related disorder characterized by abnormal sensation and an urge to move the lower limbs. Symptoms occur at rest in the evening or at night, and they are alleviated by moving the affected extremity or by walking. Although the exact etiopathogenesis of RLS remains elusive, the rapid improvement of symptoms with dopaminergic agents suggests that dopaminergic system dysfunction may be a basic mechanism. Dopaminergic agents are the best-studied agents, and are considered first-line treatment of RLS.Objective: To review the diagnostic criteria, clinical features, etiopathogenesis, and the treatment options of RLS.Methods: The suggestions are based on evidence from studies published in peer-reviewed journals, or upon a comprehensive review of the medical literature.Results/conclusion: Extensive data are available for proving the link between the dopaminergic system and RLS. A possible genetic link also has been studied extensively. Dopamine agonists, especially pramipexole and ropinirole, are particularly useful in the treatment of RLS. Pharmacological treatment should however be limited to those patients who suffer from clinically relevant RLS with impaired sleep quality or quality of life.Keywords: dopamine, levodopa, pramipexole

  9. Restless legs syndrome: literature review

    Directory of Open Access Journals (Sweden)

    Emmanouil Symvoulakis

    Full Text Available Restless legs syndrome is a distressing condition, with negative effects on sleep and daytime activities that affect personal, family and occupational life. The overall impact of restless legs syndrome on quality of life is comparable to that of chronic and frustrating conditions such as depression and diabetes. Misdiagnosis and inappropriate treatment may increase patients' suffering in terms of uncertainty, overuse or misuse of care services and lack of trust. Presenting a synthesis of the main topics in the literature on restless legs syndrome facilitates for a better understanding and its management in primary care settings.

  10. Measurement of body fat using leg to leg bioimpedance

    OpenAIRE

    Sung, R; Lau, P; Yu, C; Lam, P; Nelson, E

    2001-01-01

    AIMS—(1) To validate a leg to leg bioimpedance analysis (BIA) device in the measurement of body composition in children by assessment of its agreement with dual energy x ray absorptiometry (DXA) and its repeatability. (2) To establish a reference range of percentage body fat in Hong Kong Chinese children.
METHODS—Sequential BIA and DXA methods were used to determine body composition in 49 children aged 7-18 years; agreement between the two methods was calculated. Repea...

  11. Quality of Life in People with Leg Ulcer, Integrative Review

    Directory of Open Access Journals (Sweden)

    Daniela Alves

    2016-04-01

    Full Text Available Objective: To identify the main changes in the daily life of people with leg ulcer and how that affects the person’s quality of life. Methodology: We used the methodology PI [C] OD and selected four research articles, taken from EBSCO, PubMed, and EWMA. Results: The main changes identified in the people’s daily live with leg ulcers are physical (pain, decreased mobility, presence of exudate, bad smell from the wound and change in the style of clothing, psychological (sleep disorders, depression, anxiety, feelings of rejection and low self-steem, social (isolation, restriction in leisure activities, inability to perform household chores. Conclusions: The literature about the person’s quality of life with leg ulcer reported a significant impact in the daily life. The care provided by nurses should be centered on the person, integrating all the kind of needs and the leg ulcer must not be the sole focus of care

  12. Coupling between the Output Force and Stiffness in Different Variable Stiffness Actuators

    Directory of Open Access Journals (Sweden)

    Amir Jafari

    2014-08-01

    Full Text Available The fundamental objective in developing variable stiffness actuators is to enable the actuator to deliberately tune its stiffness. This is done through controlling the energy flow extracted from internal power units, i.e., the motors of a variable stiffness actuator (VSA. However, the stiffness may also be unintentionally affected by the external environment, over which, there is no control. This paper analysis the correlation between the external loads, applied to different variable stiffness actuators, and their resultant output stiffness. Different types of variable stiffness actuators have been studied considering springs with different types of nonlinearity. The results provide some insights into how to design the actuator mechanism and nonlinearity of the springs in order to increase the decoupling between the load and stiffness in these actuators. This would significantly widen the application range of a variable stiffness actuator.

  13. Stiff person case misdiagnosed as conversion disorder: A case report.

    Science.gov (United States)

    Razmeh, Saeed; Habibi, Amir Hasan; Sina, Farzad; Alizadeh, Elham; Eslami, Monireh

    2017-01-01

    Stiff person syndrome (SPS) is a rare neurological disease resulting in stiffness and spasm of muscles. It initially affects the axial muscles and then spread to limb muscles. Emotional stress exacerbated the symptoms and signs of the disease. The pathophysiology of the disease is caused by the decreased level of the glutamic acid decarboxylase (GAD) activity due to an autoantibody against GAD that decreases the level of gamma-aminobutyric acid (GABA). In this paper, we present a case of atypical presentation of SPS with lower limb stiffness misdiagnosed as conversion disorder. We report a patient with atypical presentation of SPS with lower limb stiffness and gait disorder misdiagnosed as conversion disorder for a year. Her antithyroid peroxidase antibody (anti-TPO Ab) level was 75 IU (normal value: 0-34 IU). Intravenous immunoglobulin (IVIG) was administered (2gr/kg, 5 days) for the patient that showed significant improvement in the follow-up visit. It is essential that in any patient with bizarre gait disorder and suspicious to conversion disorder due to the reversibility of symptoms, SPS and other movement disorder should be considered.

  14. Trunk orientation causes asymmetries in leg function in small bird terrestrial locomotion.

    Science.gov (United States)

    Andrada, Emanuel; Rode, Christian; Sutedja, Yefta; Nyakatura, John A; Blickhan, Reinhard

    2014-12-22

    In contrast to the upright trunk in humans, trunk orientation in most birds is almost horizontal (pronograde). It is conceivable that the orientation of the heavy trunk strongly influences the dynamics of bipedal terrestrial locomotion. Here, we analyse for the first time the effects of a pronograde trunk orientation on leg function and stability during bipedal locomotion. For this, we first inferred the leg function and trunk control strategy applied by a generalized small bird during terrestrial locomotion by analysing synchronously recorded kinematic (three-dimensional X-ray videography) and kinetic (three-dimensional force measurement) quail locomotion data. Then, by simulating quail gaits using a simplistic bioinspired numerical model which made use of parameters obtained in in vivo experiments with real quail, we show that the observed asymmetric leg function (left-skewed ground reaction force and longer leg at touchdown than at lift-off) is necessary for pronograde steady-state locomotion. In addition, steady-state locomotion becomes stable for specific morphological parameters. For quail-like parameters, the most common stable solution is grounded running, a gait preferred by quail and most of the other small birds. We hypothesize that stability of bipedal locomotion is a functional demand that, depending on trunk orientation and centre of mass location, constrains basic hind limb morphology and function, such as leg length, leg stiffness and leg damping. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  15. Study of stiffness and bearing capacity degradation of reinforced concrete beams under constant-amplitude fatigue.

    Science.gov (United States)

    Liu, Fangping; Zhou, Jianting; Yan, Lei

    2018-01-01

    For a reinforced concrete beam subjected to fatigue loads, the structural stiffness and bearing capacity will gradually undergo irreversible degeneration, leading to damage. Moreover, there is an inherent relationship between the stiffness and bearing capacity degradation and fatigue damage. In this study, a series of fatigue tests are performed to examine the degradation law of the stiffness and bearing capacity. The results pertaining to the stiffness show that the stiffness degradation of a reinforced concrete beam exhibits a very clear monotonic decreasing "S" curve, i.e., the stiffness of the beam decreases significantly at the start of the fatigue loading, it undergoes a linear decline phase in the middle for a long loading period, and before the failure, the bearing capacity decreases drastically again. The relationship between the residual stiffness and residual bearing capacity is determined based on the assumption that the residual stiffness and residual bearing capacity depend on the same damage state, and then, the bearing capacity degradation model of the reinforced concrete beam is established based on the fatigue stiffness. Through the established model and under the premise of the known residual stiffness degradation law, the degradation law of the bearing capacity is determined by using at least one residual bearing capacity test data, for which the parameters of the stiffness degradation function are considered as material constants. The results of the bearing capacity show that the bearing capacity degradation of the reinforced concrete beam also exhibits a very clear monotonic decreasing "S" curve, which is consistent with the stiffness degradation process and in good agreement with the experiment. In this study, the stiffness and bearing capacity degradation expressions are used to quantitatively describe their occurrence in reinforced concrete beams. In particular, the expression of the bearing capacity degradation can mitigate numerous

  16. Noninvasively assessed pulmonary artery stiffness predicts mortality in pulmonary arterial hypertension .

    NARCIS (Netherlands)

    Gan, C.T.; Lankhaar, J.W.; Westerhof, N.; Marcus, J.T.; Becker, A.; Twisk, J.W.R.; Boonstra, A.; Postmus, P.E.; Vonk Noordegraaf, A.

    2007-01-01

    Aims: Decreased total compliance of the pulmonary vascular bed is associated with increased mortality in patients with pulmonary arterial hypertension (PAH). We investigated whether proximal pulmonary artery stiffness, in terms of area distensibility and noninvasively assessed relative area change

  17. Modifiable risk factors for increased arterial stiffness in outpatient nephrology.

    Directory of Open Access Journals (Sweden)

    Usama Elewa

    Full Text Available Arterial stiffness, as measured by pulse wave velocity (PWV, is an independent predictor of cardiovascular events and mortality. Arterial stiffness increases with age. However, modifiable risk factors such as smoking, BP and salt intake also impact on PWV. The finding of modifiable risk factors may lead to the identification of treatable factors, and, thus, is of interest to practicing nephrologist. We have now studied the prevalence and correlates of arterial stiffness, assessed by PWV, in 191 patients from nephrology outpatient clinics in order to identify modifiable risk factors for arterial stiffness that may in the future guide therapeutic decision-making. PWV was above normal levels for age in 85/191 (44.5% patients. Multivariate analysis showed that advanced age, systolic BP, diabetes mellitus, serum uric acid and calcium polystyrene sulfonate therapy or calcium-containing medication were independent predictors of PWV. A new parameter, Delta above upper limit of normal PWV (Delta PWV was defined to decrease the weight of age on PWV values. Delta PWV was calculated as (measured PWV - (upper limit of the age-adjusted PWV values for the general population. Mean±SD Delta PWV was 0.76±1.60 m/sec. In multivariate analysis, systolic blood pressure, active smoking and calcium polystyrene sulfonate therapy remained independent predictors of higher delta PWV, while age, urinary potassium and beta blocker therapy were independent predictors of lower delta PWV. In conclusion, arterial stiffness was frequent in nephrology outpatients. Systolic blood pressure, smoking, serum uric acid, calcium-containing medications, potassium metabolism and non-use of beta blockers are modifiable factors associated with increased arterial stiffness in Nephrology outpatients.

  18. Loss of legs: is it or not a handicap for an orb-weaving spider?

    Science.gov (United States)

    Pasquet, Alain; Anotaux, Mylène; Leborgne, Raymond

    2011-07-01

    Leg loss is a common phenomenon in spiders, and according to the species 5% to 40% of the adults can present at least one missing leg. There is no possibility of regeneration after adult moult and the animal must manage with its missing appendages until its death. With the loss of one or more legs, female orb-weaving spiders can be penalized twice: firstly, because the legs are necessary for web construction and secondly, the legs are essential for the control of the prey after its interception by the web. During development, spiders may be also penalized because regeneration has energetic costs that take away resources for survival, growth and reproduction. All these consequences should influence negatively the development of the spider and thus its fitness. We investigated the impact of leg loss in the orb-weaving spider, Zygiella x-notata by studying its frequency in a natural population and web building and prey capture behaviours in laboratory. In field populations, 9.5% to 13%, of the adult females presented the loss of one or more legs; the majority of individuals had lost only one leg (in 48% of cases, a first one). Leg loss seems to affect all the adult spiders, as there is no difference of mass between intact spiders and those with missing leg. Data obtained with laboratory-reared spiders, showed that the loss of legs due to the moult is rare (less than 1%). Considering changes in web design, spiders with missing legs decreased their silk investment, increased the distance between spiral turns but did not change the capture surface of the web. Under our laboratory experimental conditions, spiders with one or two lost legs did not present any difference in prey capture efficiency. In laboratory conditions, spiders with lost leg(s) did not show any difference in egg sac production or in longevity (adult lifespan) compared to intact spiders.

  19. Leg pain and gynecologic malignancy.

    Science.gov (United States)

    Singh, Lilly; Stevens, Erin E

    2013-09-01

    Gynecologic malignancies affect more than 83 000 women in the United States, each year. Because the disease involves the pelvis, many patients have side effects distal to this area in their lower extremities. The differential diagnosis of leg pain can be divided into vascular, neurologic, and musculoskeletal causes. In this review article, we address numerous etiologies of leg pain, reviewing the prevalence of disease, physical examination findings, diagnostic as well as treatment modalities.

  20. Measurement and Treatment of Passive Muscle Stiffness

    DEFF Research Database (Denmark)

    Kirk, Henrik

    This PhD thesis is based on research conducted at the University of Copenhagen and Helene Elsass Center from 2012 to 2015. Measurements and treatment of passive muscle stiffness in people with cerebral palsy (CP) comprise the focus of the thesis. The thesis summarizes the results from four studies......, which aimed to investigate: 1) The development of a clinical method to evaluate and distinguish neural (reflex mediated stiffness) and non-neural (passive muscle stiffness) components of muscle stiffness in adults with CP by objective and reliable measurements. 2) The association between increased...... passive muscle, muscle strength and gait function in adults with CP 3) The effect of resistance training and gait training accordingly on muscle strength, passive muscle stiffness and functional gait in adults with CP. The first part of the thesis defines reflex mediated stiffness and passive muscle...

  1. Two-legged hopping in autism spectrum disorders

    Directory of Open Access Journals (Sweden)

    Matthew F. Moran

    2013-03-01

    Full Text Available Sensory processing deficits are common within autism spectrum disorders (ASD. Deficits have a heterogeneous dispersion across the spectrum and multimodal processing tasks are thought to magnify integration difficulties. Two-legged hopping in place in sync with an auditory cue (2.3, 3.0 Hz was studied in a group of six individuals with expressive language impaired ASD (ELI-ASD and an age-matched control group. Vertical ground reaction force data were collected and discrete Fourier transforms were utilized to determine dominant hopping cadence. Effective leg stiffness was computed through a mass-spring model representation. The ELI-ASD group were unsuccessful in matching their hopping cadence (2.21±0.30 hops•sec-1, 2.35±0.41 hops•sec-1 to either auditory cue with greater deviations at the 3.0 Hz cue. In contrast, the control group was able to match hopping cadence (2.35±0.06 hops•sec-1, 3.02±0.10 hops•sec-1 to either cue via an adjustment of effective leg stiffness. The ELI-ASD group demonstrated a varied response with an interquartile range (IQR in excess of 0.5 hops•sec-1 as compared to the control group with an IQR < 0.03 hops•sec-1. Several sensorimotor mechanisms could explain the inability of participants with ELI-ASD to modulate motor output to match an external auditory cue. These results suggest that a multimodal gross motor task can (1 discriminate performance among a group of individuals with severe autism, and (2 could be a useful quantitative tool for evaluating motor performance in individuals with ASD individuals.

  2. Comparative study of a muscle stiffness sensor and electromyography and mechanomyography under fatigue conditions.

    Science.gov (United States)

    Han, Hyonyoung; Jo, Sungho; Kim, Jung

    2015-07-01

    This paper proposes the feasibility of a stiffness measurement for muscle contraction force estimation under muscle fatigue conditions. Bioelectric signals have been widely studied for the estimation of the contraction force for physical human-robot interactions, but the correlation between the biosignal and actual motion is decreased under fatigue conditions. Muscle stiffness could be a useful contraction force estimator under fatigue conditions because it measures the same physical quantity as the muscle contraction that generates the force. Electromyography (EMG), mechanomyography (MMG), and a piezoelectric resonance-based active muscle stiffness sensor were used to analyze the biceps brachii under isometric muscle fatigue conditions with reference force sensors at the end of the joint. Compared to EMG and MMG, the change in the stiffness signal was smaller (p fatigue condition changed fatigue conditions. This result indicates that the muscle stiffness signal is less sensitive to muscle fatigue than other biosignals. This investigation provides insights into methods of monitoring and compensating for muscle fatigue.

  3. Sabot Front Borerider Stiffness vs. Dispersion: Finding the Knee in the Curve

    Directory of Open Access Journals (Sweden)

    Alan F. Hathaway

    2001-01-01

    Full Text Available In the design of armor piercing, fin-stabilized, discarding sabot projectiles, the radial stiffness of the sabot front borerider has a significant impact on the projectile's dispersion and is, therefore, an important design consideration. Whether designing a new projectile or trying to improve an existing design, projectile designers can achieve front borerider stiffness without understanding its affect on dispersion characteristics. There is a knee in the stiffness vs. dispersion curve at which a change in the sabot front borerider stiffness will have a significant impact on dispersion or no impact at all depending on whether the stiffness is increased or decreased. The subject of this paper is an analytical approach to quantitatively determine the knee in the curve. Results from using this approach on the M865 APFSDS projectile are also presented.

  4. Pacifier Stiffness Alters the Dynamics of the Suck Central Pattern Generator

    Science.gov (United States)

    Zimmerman, Emily; Barlow, Steven M.

    2008-01-01

    Variation in pacifier stiffness on non-nutritive suck (NNS) dynamics was examined among infants born prematurely with a history of respiratory distress syndrome. Three types of silicone pacifiers used in the NICU were tested for stiffness, revealing the Super Soothie™ nipple is 7 times stiffer than the Wee™ or Soothie™ pacifiers even though shape and displaced volume are identical. Suck dynamics among 20 preterm infants were subsequently sampled using the Soothie™ and Super Soothie™ pacifiers during follow-up at approximately 3 months of age. ANOVA revealed significant differences in NNS cycles/min, NNS amplitude, NNS cycles/burst, and NNS cycle periods as a function of pacifier stiffness. Infants modify the spatiotemporal output of their suck central pattern generator when presented with pacifiers with significantly different mechanical properties. Infants show a non-preference to suck due to high stiffness in the selected pacifier. Therefore, excessive pacifier stiffness may decrease ororhythmic patterning and impact feeding outcomes. PMID:19492006

  5. Restless Legs Syndrome and Leg Motor Restlessness in Parkinson's Disease.

    Science.gov (United States)

    Suzuki, Keisuke; Miyamoto, Masayuki; Miyamoto, Tomoyuki; Hirata, Koichi

    2015-01-01

    Sleep disturbances are important nonmotor symptoms in Parkinson's disease (PD) that are associated with a negative impact on quality of life. Restless legs syndrome (RLS), which is characterized by an urge to move the legs accompanied by abnormal leg sensations, can coexist with PD, although the pathophysiology of these disorders appears to be different. RLS and PD both respond favorably to dopaminergic treatment, and several investigators have reported a significant relationship between RLS and PD. Sensory symptoms, pain, motor restlessness, akathisia, and the wearing-off phenomenon observed in PD should be differentiated from RLS. RLS in PD may be confounded by chronic dopaminergic treatment; thus, more studies are needed to investigate RLS in drug-naïve patients with PD. Recently, leg motor restlessness (LMR), which is characterized by an urge to move the legs that does not fulfill the diagnostic criteria for RLS, has been reported to be observed more frequently in de novo patients with PD than in age-matched healthy controls, suggesting that LMR may be a part of sensorimotor symptoms intrinsic to PD. In this paper, we provide an overview of RLS, LMR, and PD and of the relationships among these disorders.

  6. Soft Legged Wheel-Based Robot with Terrestrial Locomotion Abilities

    Directory of Open Access Journals (Sweden)

    Ali Sadeghi

    2016-12-01

    Full Text Available In recent years robotics has been influenced by a new approach, soft-robotics, bringing the idea that safe interaction with user and more adaptation to the environment can be achieved by exploiting easily deformable materials and flexible components in the structure of robots. In 2016, the soft-robotics community has promoted a new robotics challenge, named RoboSoft Grand Challenge, with the aim of bringing together different opinions on the usefulness and applicability of softness and compliancy in robotics. In this paper we describe the design and implementation of a terrestrial robot based on two soft legged wheels. The tasks predefined by the challenge were set as targets in the robot design, which finally succeeded to accomplish all the tasks. The wheels of the robot can passively climb over stairs and adapt to slippery grounds using two soft legs embedded in their structure. The soft legs, fabricated by integration of soft and rigid materials and mounted on the circumference of a conventional wheel, succeed to enhance its functionality and easily adapt to unknown grounds. The robot has a semi stiff tail that helps in the stabilization and climbing of stairs. An active wheel is embedded at the extremity of the tail in order to increase the robot maneuverability in narrow environments. Moreover two parallelogram linkages let the robot to reconfigure and shrink its size allowing entering inside gates smaller than its initial dimensions.

  7. Design of a Variable Stiffness Soft Dexterous Gripper

    Science.gov (United States)

    Nefti-Meziani, Samia; Davis, Steve

    2017-01-01

    Abstract This article presents the design of a variable stiffness, soft, three-fingered dexterous gripper. The gripper uses two designs of McKibben muscles. Extensor muscles that increase in length when pressurized are used to form the fingers of the gripper. Contractor muscles that decrease in length when pressurized are then used to apply forces to the fingers through tendons, which cause flexion and extension of the fingers. The two types of muscles are arranged to act antagonistically and this means that by raising the pressure in all of the pneumatic muscles, the stiffness of the system can be increased without a resulting change in finger position. The article presents the design of the gripper, some basic kinematics to describe its function, and then experimental results demonstrating the ability to adjust the bending stiffness of the gripper's fingers. It has been demonstrated that the fingers' bending stiffness can be increased by more than 150%. The article concludes by demonstrating that the fingers can be closed loop position controlled and are able to track step and sinusoidal inputs. PMID:29062630

  8. Leg movements during wakefulness in restless legs syndrome: time structure and relationships with periodic leg movements during sleep.

    Science.gov (United States)

    Ferri, Raffaele; Manconi, Mauro; Plazzi, Giuseppe; Bruni, Oliviero; Cosentino, Filomena I I; Ferini-Strambi, Luigi; Zucconi, Marco

    2012-05-01

    Approximately one third of patients with restless legs syndrome (RLS) also show periodic leg movements (PLM) during relaxed wake fulness (PLMW). In contrast with the large amount of data published on periodic leg movements during sleep (PLMS), PLMW have received less attention from the scientific community. The objective of this study was to evaluate the correlations/differences of time-structure and response to a dopamine-agonist between PLMW and PLMS in patients with RLS. Ninety idiopathic RLS patients and 28 controls were recruited. Subjects underwent clinical and neurophysiological evaluation, hematological screening, and one or two consecutive full-night polysomnographic studies. A subset of patients received 0.25mg of pramipexole or placebo before the second recording. Polysomnographic recordings were scored and LM activity was analyzed during sleep and during the epochs of wakefulness occurring during the first recording hour. RLS patients had higher LM activity during wakefulness than controls, but with a similar periodicity. Even if correlated, the ability of the PLMW index to predict the PLMS index decreased with increasing LM activity. Intermovement intervals during wakefulness showed one peak only at approximately 4s, gradually decreasing with increasing interval in both patients and controls. The effect of pramipexole was very limited and involved the small periodic portion of LM activity during wakefulness. PLMW index and PLMS index were correlated; however, the magnitude of this correlation was not sufficient to suggest that PLMW can be good predictors of PLMS. Short-interval LM activity during wakefulness and sleep might be linked to the severity of sleep disruption in RLS patients and the differences between their features obtained during wakefulness or sleep might be relevant for the diagnosis of sleep disturbances in RLS. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Decrease in vibroactivity of gear drives

    Science.gov (United States)

    Dyundik, O. S.; Zgonnik, I. P.

    2018-01-01

    The analysis of technical and technological solutions to reduce the influence of dynamic intermating process to vibroactivity of a gear drive is carried out. The problem of a complete elimination has no solution due to a discrete way of power flow transformation by a gear drive. It is shown that a reduction of mesh stiffness is a controlled parameter in vibroactivity decrease. We have proposed to reduce the stiffness by means of a gear rim radial cut that provides small initial and stepwise variable stiffness of gearing. The technical solutions resulting in a smooth, dependent on a power flow running of stiffness by means of built-in control chain and usage of elastomeric materials are given. As a result, it is noted that the reduction of mesh stiffness at the same time leads to the increase in static deformation δ, and the dynamic load under intermating decreases. Elastomeric parameters’ variation t can provide the achievement of calculated mesh stiffness, depending on a variable power flow.

  10. A variable stiffness joint with electrospun P(VDF-TrFE-CTFE) variable stiffness springs

    NARCIS (Netherlands)

    Carloni, Raffaella; Lapp, Valerie I.; Cremonese, Andrea; Belcari, Juri; Zucchelli, Andrea

    This letter presents a novel rotational variable stiffness joint that relies on one motor and a set of variable stiffness springs. The variable stiffness springs are leaf springs with a layered design, i.e., an electro-active layer of electrospun aligned nanofibers of poly(vinylidene

  11. Restless legs syndrome and periodic leg movements of sleep.

    Science.gov (United States)

    Rye, David B; Trotti, Lynn Marie

    2012-11-01

    Women are more commonly affected than men by restless legs syndrome, and prevalence is highest amongst those of northern European heritage. The motor manifestations include nonvolitional myoclonus (periodic leg movements). Disinhibition of spinal sensorimotor circuits may underlie these primary features and can be affected by peripheral as well as supraspinal networks. Insufficient mobilizable iron stores increase expressivity in some individuals. The sensorimotor features are relieved by dopamine, especially dopamine agonists, gabapentin and its derivatives, and opioids. A diagnosis relies on recognition of key primary and supportive features, and treatments are generally well tolerated, efficacious, and life-changing. Copyright © 2012 Elsevier Inc. All rights reserved.

  12. Epidemiology of leg amputation

    DEFF Research Database (Denmark)

    Ebskov, L B; Schroeder, T V; Holstein, P E

    1994-01-01

    The number of amputations performed for vascular disease in Denmark has decreased from 1777 (34.5 per 100,000 population) in 1983 to 1288 (25.0 per 100,000) in 1990, a reduction of 28 per cent. This decline coincided with an increase in vascular surgical activity of up to 100 per cent, including ...

  13. Stiffness and damping in mechanical design

    National Research Council Canada - National Science Library

    Rivin, Eugene I

    1999-01-01

    ... important conceptual issues are stiffness of mechanical structures and their components and damping in mechanical systems sensitive to and/or generating vibrations. Stiffness and strength are the most important criteria for many mechanical designs. However, although there are hundreds of books on various aspects of strength, and strength issues ar...

  14. Optimising geometry for maximum supporting stiffnesses

    NARCIS (Netherlands)

    Brouwer, Dannis Michel; Wiersma, Hedzer; Boer, Steven; Aarts, Ronald G.K.M.

    2013-01-01

    Flexure hinges inherently lose stiffness in supporting directions when deflected. This article presents a method for optimising the geometry of flexure hinges, aimed at maximising supporting stiffnesses. In addition, the new -Flexure Hinge design is presented. The considered hinges are subjected to

  15. Stiffness Control of Surgical Continuum Manipulators.

    Science.gov (United States)

    Mahvash, Mohsen; Dupont, Pierre E

    2011-04-01

    This paper introduces the first stiffness controller for continuum robots. The control law is based on an accurate approximation of a continuum robot's coupled kinematic and static force model. To implement a desired tip stiffness, the controller drives the actuators to positions corresponding to a deflected robot configuration that produces the required tip force for the measured tip position. This approach provides several important advantages. First, it enables the use of robot deflection sensing as a means to both sense and control tip forces. Second, it enables stiffness control to be implemented by modification of existing continuum robot position controllers. The proposed controller is demonstrated experimentally in the context of a concentric tube robot. Results show that the stiffness controller achieves the desired stiffness in steady state, provides good dynamic performance, and exhibits stability during contact transitions.

  16. Rolling Element Bearing Stiffness Matrix Determination (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; Parker, R.

    2014-01-01

    Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.

  17. Shifting the optimal stiffness for cell migration.

    Science.gov (United States)

    Bangasser, Benjamin L; Shamsan, Ghaidan A; Chan, Clarence E; Opoku, Kwaku N; Tüzel, Erkan; Schlichtmann, Benjamin W; Kasim, Jesse A; Fuller, Benjamin J; McCullough, Brannon R; Rosenfeld, Steven S; Odde, David J

    2017-05-22

    Cell migration, which is central to many biological processes including wound healing and cancer progression, is sensitive to environmental stiffness, and many cell types exhibit a stiffness optimum, at which migration is maximal. Here we present a cell migration simulator that predicts a stiffness optimum that can be shifted by altering the number of active molecular motors and clutches. This prediction is verified experimentally by comparing cell traction and F-actin retrograde flow for two cell types with differing amounts of active motors and clutches: embryonic chick forebrain neurons (ECFNs; optimum ∼1 kPa) and U251 glioma cells (optimum ∼100 kPa). In addition, the model predicts, and experiments confirm, that the stiffness optimum of U251 glioma cell migration, morphology and F-actin retrograde flow rate can be shifted to lower stiffness by simultaneous drug inhibition of myosin II motors and integrin-mediated adhesions.

  18. Promethus Hot Leg Piping Concept

    International Nuclear Information System (INIS)

    AM Girbik; PA Dilorenzo

    2006-01-01

    The Naval Reactors Prime Contractor Team (NRPCT) recommended the development of a gas cooled reactor directly coupled to a Brayton energy conversion system as the Space Nuclear Power Plant (SNPP) for NASA's Project Prometheus. The section of piping between the reactor outlet and turbine inlet, designated as the hot leg piping, required unique design features to allow the use of a nickel superalloy rather than a refractory metal as the pressure boundary. The NRPCT evaluated a variety of hot leg piping concepts for performance relative to SNPP system parameters, manufacturability, material considerations, and comparison to past high temperature gas reactor (HTGR) practice. Manufacturability challenges and the impact of pressure drop and turbine entrance temperature reduction on cycle efficiency were discriminators between the piping concepts. This paper summarizes the NRPCT hot leg piping evaluation, presents the concept recommended, and summarizes developmental issues for the recommended concept

  19. Leg ulcers due to hyperhomocysteinemia

    Directory of Open Access Journals (Sweden)

    Krupa Shankar D

    2006-01-01

    Full Text Available Chronic leg ulcers are rare in young adults and generally indicate a vascular cause. We report a case of a 26-year-old man with leg ulcers of eight months duration. Doppler study indicated venous incompetence and a postphlebitic limb. However, as the distribution and number of ulcers was not consistent with stasis alone and no features of collagen vascular disease were noted, a hyperviscosity state was considered and confirmed with significantly elevated homocysteine level in the serum. Administration of vitamins B1, B2, B6 and B12, trimethyl-glycine, mecobalamine, folic acid and povidone iodine dressings with culture-directed antibiotic therapy led to a satisfactory healing of ulcers over a period of one month. Hyperhomocysteinemia must be considered in the differential diagnosis of leg ulcers in young individuals.

  20. Diurnal variations in lower leg subcutaneous blood flow rate in patients with chronic venous leg ulcers

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Kristensen, J K

    1991-01-01

    The blood flow rate in subcutaneous adipose tissue was measured on the lower legs of 11 patients with chronic lower-leg venous insufficiency and ulceration and in eight age-matched control subjects for 12-20 h, under ambulatory conditions, using the 133Xe wash-out technique with portable Cadmium...... telluride (CdTe(Cl)) detectors. In both groups, the change from an upright to a supine position at the beginning of the night period elicited an instantaneous increment in the blood flow rate of 30-40% with a decrease in the central and local postural sympathetic vasoconstrictor activity. After...... approximately 1 h of sleep, a considerable increase in blood flow rate was seen in both patient and control groups which persisted for nearly 100 min. In the patient group, the mean increase was 137% compared to a mean increase of 68% in the control group (P less than 0.01). The blood flow then returned...

  1. Cross-legged Gods and One-legged Foresters

    NARCIS (Netherlands)

    Petrovskaia, N.I.

    The present article is a re-evaluation of a marvellous element in a medieval Welsh romance, Chwedl Iarlles y Ffynnawn ‘Tale of the Lady of the Fountain’, also known as Owein. One of the characters encountered by the hero is a one-eyed one-legged dark giant forester who appears to have a particular

  2. The one-leg standing radiograph

    OpenAIRE

    Pinsornsak, P.; Naratrikun, K.; Kanitnate, S.; Sangkomkamhang, T.

    2016-01-01

    Objectives The purpose of this study was to compare the joint space width between one-leg and both-legs standing radiographs in order to diagnose a primary osteoarthritis of the knee. Methods Digital radiographs of 100 medial osteoarthritic knees in 50 patients were performed. The patients had undergone one-leg standing anteroposterior (AP) views by standing on the affected leg while a both-legs standing AP view was undertaken while standing on both legs. The severity of the osteoarthritis wa...

  3. Associations of Leg Fat Accumulation with Adiposity-Related Biological Factors and Risk of Metabolic Syndrome

    Science.gov (United States)

    Zhang, Xiaomin; Hu, Emily A.; Wu, Hongyu; Malik, Vasanti; Sun, Qi

    2012-01-01

    The association between regional fat mass distribution and cardiometabolic risk factors has been inconsistent in the literature, and data for ethnic minority groups, such as non-Hispanic blacks and Hispanics, are lacking. We aimed to examine this association among 8802 US residents who participated in the 1999-2004 US National Health and Nutrition Examination Survey (NHANES). Body composition was measured using dual-energy X-ray absorptiometry (DXA). Leg fat indices included leg fat mass (FM), leg fat mass percent (FM%), leg to whole body FM ratio (leg/whole) and leg to trunk FM ratio (leg/trunk). We evaluated the correlation between leg fat indices and adiposity-related risk factors, as well as the association of these indices with metabolic syndrome (MetS). After adjusting for covariates including age, gender, and trunk FM or trunk FM%, higher leg FM and leg FM% were, in general, correlated favorably with adiposity-related risk factors and associated with lower odds of MetS in all ethnicities, including non-Hispanic whites and blacks and Hispanic groups. In addition, in all multivariate-adjusted models, leg/whole and leg/trunk ratios were strongly associated with lower levels of most risk factors and decreased odds of MetS in these ethnicities (all odds ratios comparing extreme quintiles leg fat accumulation is inversely associated with adiposity-related biological factors and risk of MetS in both whites and ethnic groups, suggesting that regional fat distribution plays an important role in the etiology of adiposity-related diseases in these populations. PMID:23404933

  4. Effect of elastic bandage wraps on leg edema in patients before and after liver transplant.

    Science.gov (United States)

    Mathews, Susan; James, Shantell; Anderson, Janet D; Merchant, Mehwish; Benenati, Sonia; Henry, Samantha; Comrie, Gem; Pirani, Shamsa; Zellinger, Mary

    2015-12-01

    Few studies have evaluated the benefits of short-term use of compression therapy to prevent or minimize edema and/or pain in the legs of acutely ill, hospitalized patients without venous leg ulcers. To determine if the use of elastic bandage wraps of the leg in patients before and after liver transplant decreases edema formation and pain in the leg. Study Population-A convenience sample of inpatients before and after liver transplant. Pretest, posttest, randomized controlled trial with each participant serving as his or her own control. Intervention-Elastic bandage wrap applied to leg for 8 hours. Edema and pain in leg. In 13 patients before and 11 patients after liver transplant, the mean (SD) change in leg circumference after a single 8-hour application of an elastic bandage wrap was -2.6 (2.2) cm at the ankle and -3.1 (2.9) cm at midcalf for wrapped legs, as opposed to -0.4 (1.6) cm at the ankle and 1.0 (2.8) cm at midcalf for unwrapped legs (PLeg pain, measured on a visual analog scale, was significantly lower for the wrapped (mean [SD], 10.3 [26.5] mm) versus the unwrapped (20.3 [33.5] mm) leg (P=.04). In inpatients before and after liver transplant, the application of elastic bandage wraps to 1 leg for an 8-hour period led to significantly less edema formation and pain compared with the unwrapped leg. These results support the use of elastic bandage wraps in liver transplant patients to reduce leg edema and improve comfort.

  5. Cloacal impaction with cloacolith in a black-legged seriema ...

    African Journals Online (AJOL)

    Ibrahim Eldaghayes

    2017-12-07

    Dec 7, 2017 ... A 5-year-old intact female black-legged seriema (Chunga burmeisteri) was presented for behavioral changes and slight decrease in activity (minor ... panel did not reveal any abnormalities as compared to reference individuals from .... Cloacolith in a blue-fronted Amazon parrot. (Amazona aestiva). J. Avian ...

  6. Dynamic stiffness of suction caissons - vertical vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Ibsen, Lars Bo; Liingaard, M.; Andersen, Lars

    2006-12-15

    The dynamic response of offshore wind turbines are affected by the properties of the foundation and the subsoil. The purpose of this report is to evaluate the dynamic soil-structure interaction of suction caissons for offshore wind turbines. The investigation is limited to a determination of the vertical dynamic stiffness of suction caissons. The soil surrounding the foundation is homogenous with linear viscoelastic properties. The dynamic stiffness of the suction caisson is expressed by dimensionless frequency-dependent dynamic stiffness coefficients corresponding to the vertical degree of freedom. The dynamic stiffness coefficients for the foundations are evaluated by means of a dynamic three-dimensional coupled Boundary Element/Finite Element model. Comparisons are made with known analytical and numerical solutions in order to evaluate the static and dynamic behaviour of the Boundary Element/Finite Element model. The vertical frequency dependent stiffness has been determined for different combinations of the skirt length, Poisson's ratio and the ratio between soil stiffness and skirt stiffness. Finally the dynamic behaviour at high frequencies is investigated. (au)

  7. Back Pain with Leg Pain.

    Science.gov (United States)

    Vulfsons, Simon; Bar, Negev; Eisenberg, Elon

    2017-07-01

    The clinical diagnostic dilemma of low back pain that is associated with lower limb pain is very common. In relation to back pain that radiates to the leg, the International Association for the Study of Pain (IASP) states: "Pain in the lower limb should be described specifically as either referred pain or radicular pain. In cases of doubt no implication should be made and the pain should be described as pain in the lower limb." Bogduks' editorial in the journal PAIN (2009) helps us to differentiate and define the terms somatic referred pain, radicular pain, and radiculopathy. In addition, there are other pathologies distal to the nerve root that could be relevant to patients with back pain and leg pain such as plexus and peripheral nerve involvement. Hence, the diagnosis of back pain with leg pain can still be challenging. In this article, we present a patient with back and leg pain. The patient appears to have a radicular pain syndrome, but has no neurological impairment and shows signs of myofascial involvement. Is there a single diagnosis or indeed two overlapping syndromes? The scope of our article encompasses the common diagnostic possibilities for this type of patient. A discussion of treatment is beyond the scope of this article and depends on the final diagnosis/diagnoses made.

  8. Kan leg skabe fremtidens vindere?

    DEFF Research Database (Denmark)

    Holm, Claus

    2006-01-01

    Dansk Boldspil Union skruer ned for den præstationsorienterede tilgang til børnefodbold. I stedet skal børnenes leg med bolden i fokus. Målet er at forhindre massivt frafald i børne- og ungdomsfodbolden og højne niveauet hos topspillerne....

  9. Doppler ultrasound exam of an arm or leg

    Science.gov (United States)

    Peripheral vascular disease - Doppler; PVD - Doppler; PAD - Doppler; Blockage of leg arteries - Doppler; Intermittent claudication - Doppler; Arterial insufficiency of the legs - Doppler; Leg pain and ...

  10. Research on Detection of Machine Stiffness

    Directory of Open Access Journals (Sweden)

    Wang Li-Jie

    2015-01-01

    Full Text Available Machine tool stiffness is a principal factor affecting machine tool precision, traditional methods can only be used to detect limited categories of machine tools. The paper introduces a new scheme to detect machine tool stiffness on the basis of dynamic detection of machine tool stiffness considering its characteristics and stress state during processing. An experiment conducted in turn-milling machining center CH7516GS indicated by comparison that statics analysis of finite elements matched the experimental result well, which provided precise original data for design of improved machine tool precision and access to design of precision detection equipment for other types of machine tools.

  11. Observed variations of monopile foundation stiffness

    DEFF Research Database (Denmark)

    Kallehave, Dan; Thilsted, C.L.; Diaz, Alberto Troya

    2015-01-01

    The soil-structure stiffness of monopile foundations for offshore wind turbines has a high impact on the fatigue loading during normal operating conditions. Thus, a robust design must consider the evolution of pile-soil stiffness over the lifetime of the wind farm. This paper present and discuss ...... events, followed by a complete regain to a pre-storm level when the storm subsided. In additional, no long term variations of the pile-soil stiffness was observed. The wind turbine is located in dense to very dense sand deposits....

  12. Leg Muscle Mass and Foot Symptoms, Structure, and Function: The Johnston County Osteoarthritis Project.

    Science.gov (United States)

    Golightly, Yvonne M; Dufour, Alyssa B; Hannan, Marian T; Hillstrom, Howard J; Katz, Patricia P; Jordan, Joanne M

    2016-03-01

    Loss of muscle mass occurs with aging and in lower limbs it may be accelerated by foot problems. In this cross-sectional analysis, we evaluated the relationship of leg muscle mass to foot symptoms (presence or absence of pain, aching, or stiffness), structure while standing (high arch or low arch), and function while walking (pronated or supinated) in a community-based study of Caucasian and African American men and women who were 50-95 years old. In the Johnston County Osteoarthritis Project, leg muscle mass was measured with whole body dual-energy x-ray absorptiometry, and plantar foot pressure data, using predetermined values, were used to classify foot structure and function. Sex-specific crude and adjusted (age, body mass index, and race) linear regression models examined associations of leg muscle mass index (Leg muscle mass [kg]/Height [m](2)) with foot symptoms, structure, and function. Complete data were available for 1,037 participants (mean age 68 years, mean body mass index 31 kg/m(2), 68% women, 29% African American). In women, pronated foot function was associated with lower leg muscle mass in crude (p = .02), but not adjusted (p = .22), models. A low arch was associated with a higher leg muscle mass in adjusted models for both men and women (p Leg muscle mass was associated with foot structure in our biracial sample, whereas relations between leg muscle mass and foot function were attenuated by age, body mass index, and race. Future longitudinal analyses are needed to explain the temporal relationship between these conditions and how they relate to other aspects of impairment and physical function. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. A highly adaptive magnetorheological fluid robotic leg for efficient terrestrial locomotion

    Science.gov (United States)

    Jiang, Nan; Sun, Shuaishuai; Ouyang, Yiming; Xu, Min; Li, Weihua; Zhang, Shiwu

    2016-09-01

    To survive in nature, animals adjust the characteristics of their legs or fins to adapt the motion to their environment. Inspired by the locomotion of animals, a study on the tunable stiffness and damping of a leg will help in the development of intelligent locomotion robots. In this paper we report on the development and experiment of a novel and simple robotic leg that can be adapted to the environment via a smart magnetorheological fluid (MRF). The robotic leg consists of a rotation MRF damper, a torsional spring, a ‘foot’ and a ‘leg’. The curved part of the ‘foot’ makes contact with the grounds while the other end is linked to an outer cylinder of the MRF damper with an inelastic cable. The variable force arm rising from the MRF damper and the torsional spring can help the leg adapt to a changing environment. The characteristics of the MRF damper have been investigated and a model is built to describe its mechanical features when different currents are applied to the MRF damper. A test on a linear dynamic test instrument has been conducted to verify the accuracy of the model. The robotic leg is installed in a locomotion platform to investigate the speed of its locomotion and the cost of the transport; the result demonstrated the feasibility and adaptability of the leg when walking on hard terrain. Its simple structure, high adaptability, and easy control of the MRF leg helped in the design and development of a high performance field robot that can adapt to various environments.

  14. Effects of string stiffness on muscle fatigue after a simulated tennis match.

    Science.gov (United States)

    Fabre, Jean Bernard; Martin, Vincent; Borelli, Gil; Theurel, Jean; Grélot, Laurent

    2014-06-01

    We tested the influence of string stiffness on the occurrence of forearm muscle fatigue during a tennis match. Sixteen tennis players performed two prolonged simulated tennis matches with low-stiffness or high-stiffness string. Before and immediately after exercise, muscle fatigability was evaluated on the forearm muscles during a maximal intermittent gripping task. Groundstroke ball speeds and the profile of acceleration of the racquet frame at collision were recorded during each match. The peak-to-peak amplitude of acceleration and the resonant frequency of the frame were significantly greater with high- (5060 ± 1892 m/s(2) and 204 ± 29 Hz, respectively) than with low-stiffness string (4704 ± 1671 m/s(2) and 191 ± 16 Hz, respectively). The maximal and the averaged gripping forces developed during the gripping task were significantly reduced after the tennis match with high- (-15 ± 14%, and -22 ± 14%, respectively), but not with low-stiffness string. The decrease of ball speed during the simulated matches tended to be greater with high- than with low-stiffness string (P = .06). Hence, playing tennis with high-stiffness string promotes forearm muscle fatigue development, which could partly contribute to the groundstroke ball speed decrement during the game.

  15. Research on a novel high stiffness axial passive magnetic bearing for DGMSCMG

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jinji [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beihang University, 100191 (China); Wang, Chun' e [Beijing Institute of Automatic Control Equipment, 100074 (China); Le, Yun [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beihang University, 100191 (China)

    2016-08-15

    To increase the displacement stiffness and decrease power loss of double gimbals magnetically suspended control momentum gyro (DGMSCMG), this paper researches a new structure of axial passive magnetic bearing (APMB). Different from the existing APMB, the proposed APMB is composed of segmented permanent magnets and magnetic rings. The displacement stiffness and angular stiffness expressions are derived by equivalent magnetic circuit method and infinitesimal method based on the end magnetic flux. The relationships are analyzed between stiffness and structure parameters such as length of air gap, length of permanent magnet, height of permanent magnet and end length of magnetic ring. Besides, the axial displacement stiffness measurement method of the APMB is proposed, and it verified the correctness of proposed theoretical method. The DGMSCMG prototype is manufactured and the slow-down characteristic experiment is carried out, and the experimental result reflects the low power loss feature of the APMB. - Highlights: • A novel high stiffness axial passive magnetic bearing for DGMSCMG. • The proposed APMB is composed of segmented permanent magnets and magnetic rings. • The APMB is analyzed by EMCM and infinitesimal method based on the end magnetic flux. • The axial displacement stiffness measurement method of the APMB is proposed. • The DGMSCMG is manufactured and proved the correctness of theoretical analysis.

  16. Extracellular matrix stiffness causes systematic variations in proliferation and chemosensitivity in myeloid leukemias.

    Science.gov (United States)

    Shin, Jae-Won; Mooney, David J

    2016-10-25

    Extracellular matrix stiffness influences biological functions of some tumors. However, it remains unclear how cancer subtypes with different oncogenic mutations respond to matrix stiffness. In addition, the relevance of matrix stiffness to in vivo tumor growth kinetics and drug efficacy remains elusive. Here, we designed 3D hydrogels with physical parameters relevant to hematopoietic tissues and adapted them to a quantitative high-throughput screening format to facilitate mechanistic investigations into the role of matrix stiffness on myeloid leukemias. Matrix stiffness regulates proliferation of some acute myeloid leukemia types, including MLL-AF9 + MOLM-14 cells, in a biphasic manner by autocrine regulation, whereas it decreases that of chronic myeloid leukemia BCR-ABL + K-562 cells. Although Arg-Gly-Asp (RGD) integrin ligand and matrix softening confer resistance to a number of drugs, cells become sensitive to drugs against protein kinase B (PKB or AKT) and rapidly accelerated fibrosarcoma (RAF) proteins regardless of matrix stiffness when MLL-AF9 and BCR-ABL are overexpressed in K-562 and MOLM-14 cells, respectively. By adapting the same hydrogels to a xenograft model of extramedullary leukemias, we confirm the pathological relevance of matrix stiffness in growth kinetics and drug sensitivity against standard chemotherapy in vivo. The results thus demonstrate the importance of incorporating 3D mechanical cues into screening for anticancer drugs.

  17. Military boot attenuates axial loading to the lower leg.

    Science.gov (United States)

    Yoganandan, Narayan; Schlick, Michael; Arun, Mike W J; Pintar, Frank A

    2014-01-01

    Biomechanical tests to understand injury mechanisms and derive injury tolerance information using Post-Mortem Human Subjects (PMHS) have not used foot protection and they have primarily focused on civilian environments such as automotive and athletic- and sports-related events. As military personnel use boots, tests with the boot are required to understand their effect on attenuating lower leg loads. The purpose of this study was therefore, to determine the modulation of human lower leg kinematics with boot compressions and share of the force absorbed by the boot from underbody blast loading. Axial impacts were delivered to the Hybrid III dummy lower leg in the neutral position. The dummy leg was instrumented with its internal upper and lower tibia load cells, and in addition, a knee load cell was attached to the proximal end. Tests were conducted at 4.4 to 8.9 m/s, with and without boots, and repeat tests were done. Morphologies of the force-time responses were similar at the three load cell locations and for all input combinations and booted and unbooted conditions. However, booted tests resulted in considerably lower maximum forces (approximately two-third reduction) than unbooted tests. These results clearly show that boots can absorb a considerable share of the impact energy and decrease impact loads transmitted to the lower leg under vertical loading, thus necessitating the generation of tolerance data using PMHS for this environment.

  18. Restless legs syndrome in hemodialysis patients

    Directory of Open Access Journals (Sweden)

    Shahram Rafie

    2016-01-01

    Full Text Available Restless legs syndrome (RLS is a neurological disorder characterized by uncomfortable sensation of paresthesia in legs that subsequently causes involuntary and continuous movement of the lower limbs, especially at rest. Its prevalence in hemodialysis is more than that in the general population. Different risk factors have been suggested for RLS. We studied the prevalence and risk factors of RLS in 137 hemodialysis patients followed up at our center. The patients completed at least three months on dialysis and fulfilled four criteria for the diagnosis of RLS. We compared the patients with and without RLS, and the odds ratios (ORs were estimated by the logistic regression models. The prevalence of RLS was 36.5% in the study patients. Among the variables, diabetes was the only predicting factor for the development of RLS. The diabetic patients may be afflicted with RLS 2.25 times more than the non-diabetics. Women developed severe RLS 5.23 times more than men. Neurodegeneration, decrease in dopamine level, higher total oxidant status, and neuropathy in diabetic patients may explain the RLS symptoms.

  19. Comparison of arterial stiffness and microcirculatory changes following abdominal aortic aneurysm grafting.

    LENUS (Irish Health Repository)

    Moloney, M A

    2010-11-11

    BACKGOUND: Abdominal aortic aneurysm (AAA) surgery provides a unique opportunity to study the impact of arterial stiffness on central haemodynamics, reflected in augmentation index (AI). The aneurysmal aorta is significantly stiffer than undilated age-matched aorta. AIM: We investigated whether replacement of an aneurysmal aorta with a compliant graft would result in a decrease in AI, which would thus decrease myocardial workload parameters. METHODS: Patients undergoing elective open or endovascular AAA repair were assessed with applanation tonometry and laser fluximetry pre-operatively, immediately and long-term post-operatively. RESULTS: Replacement of a small segment of abnormal conduit vessel resulted in improvements in AI, demonstrating that arterial stiffness can be surgically manipulated. CONCLUSIONS: These results reflect a decreased myocardial workload post-aortic grafting. This decrease in AI is important from a risk factor management perspective, and arterial stiffness should become a further recognised and screened for risk factor in patients with known aneurysmal disease.

  20. Comparison of arterial stiffness and microcirculatory changes following abdominal aortic aneurysm grafting.

    LENUS (Irish Health Repository)

    Moloney, M A

    2012-02-01

    BACKGOUND: Abdominal aortic aneurysm (AAA) surgery provides a unique opportunity to study the impact of arterial stiffness on central haemodynamics, reflected in augmentation index (AI). The aneurysmal aorta is significantly stiffer than undilated age-matched aorta. AIM: We investigated whether replacement of an aneurysmal aorta with a compliant graft would result in a decrease in AI, which would thus decrease myocardial workload parameters. METHODS: Patients undergoing elective open or endovascular AAA repair were assessed with applanation tonometry and laser fluximetry pre-operatively, immediately and long-term post-operatively. RESULTS: Replacement of a small segment of abnormal conduit vessel resulted in improvements in AI, demonstrating that arterial stiffness can be surgically manipulated. CONCLUSIONS: These results reflect a decreased myocardial workload post-aortic grafting. This decrease in AI is important from a risk factor management perspective, and arterial stiffness should become a further recognised and screened for risk factor in patients with known aneurysmal disease.

  1. A comparison of one-legged and two-legged countermovement jumps

    NARCIS (Netherlands)

    van Soest, A J; Roebroeck, M.E.; Bobbert, M F; Huijing, P A; van Ingen Schenau, G J

    1985-01-01

    Ten well-trained male volleyball players performed one-legged and two-legged vertical countermovement jumps. Ground reaction forces, cinematographic data, and electromyographic data were recorded. Jumping height in one-legged jumps was 58.5% of that reached in two-legged jumps. Mean net torques in

  2. Determination of 6 stiffnesses for a press

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Eriksen, Morten; Wanheim, Tarras

    2000-01-01

    The industry is increasingly demanding for better tolerances at cold forged products caused by the tough competition at the market. Near net-shape or net-shape production save resources for machining and reduce therefore also the material costs. During the forming process, the reaction forces from...... in which the press has the highest stiffness. Furthermore, knowledge about the stiffnesses of all presses in a production system makes it possible to choose the press which best fit to a specific process....

  3. Stiffness of Railway Soil-Steel Structures

    Directory of Open Access Journals (Sweden)

    Machelski Czesław

    2015-12-01

    Full Text Available The considerable influence of the soil backfill properties and that of the method of compacting it on the stiffness of soil-steel structures is characteristic of the latter. The above factors (exhibiting randomness become apparent in shell deformation measurements conducted during construction and proof test loading. A definition of soil-shell structure stiffness, calculated on the basis of shell deflection under the service load, is proposed in the paper. It is demonstrated that the stiffness is the inverse of the deflection influence function used in structural mechanics. The moving load methodology is shown to be useful for testing, since it makes it possible to map the shell deflection influence line also in the case of group loads (concentrated forces, as in bridges. The analyzed cases show that the shell’s span, geometry (static scheme and the height of earth fill influence the stiffness of the structure. The soil-steel structure’s characteristic parameter in the form of stiffness k is more suitable for assessing the quality of construction works than the proposed in code geometric index ω applied to beam structures. As shown in the given examples, parameter k is more effective than stiffness parameter λ used to estimate the deformation of soil-steel structures under construction. Although the examples concern railway structures, the methodology proposed in the paper is suitable also for road bridges.

  4. [Restless legs syndrome and nocturnal leg pain : Differential diagnosis and treatment].

    Science.gov (United States)

    Hornyak, M; Stiasny-Kolster, K; Evers, S; Happe, S

    2011-09-01

    Pain in the legs belongs to the five most frequent regional pain symptoms. Restless legs syndrome (RLS) presents a particular differential diagnosis for pain in the legs, which is characterized by a nocturnal urge to move the legs often associated with painful sensations in the legs. It is one of the most common neurological disorders and probably the leading cause of nocturnal pain in the legs. In this overview, the diagnosis and therapy of RLS as well as aspects of pain therapy of the disorder are presented. In addition, the differential diagnoses for exclusion of other specific causes of nocturnal pain in the legs are discussed.

  5. Vascular risk factors, cardiovascular disease and restless legs syndrome in men

    Science.gov (United States)

    Winter, Anke C.; Berger, Klaus; Glynn, Robert J; Buring, Julie E.; Gaziano, J. Michael; Schürks, Markus; Kurth, Tobias

    2012-01-01

    Background Prevalences of vascular risk factors, cardiovascular disease and restless legs syndrome increase with age. Prior studies analyzing the associations between vascular risk factors, cardiovascular disease, and restless legs syndrome found controversial results. We therefore aim to evaluate the association between prevalent vascular risk factors, prevalent cardiovascular disease and restless legs syndrome. Methods We conducted a cross-sectional study among 22,786 participants of the US Physicians’ Health Studies I and II. Restless legs syndrome was classified according to the four minimal diagnostic criteria. Vascular risk factors and restless legs syndrome symptoms were self-reported. Prevalent cardiovascular disease events including major cardiovascular disease, stroke and myocardial infarction were confirmed by medical record review. Age- and multivariable-adjusted logistic regression models were used to evaluate the association between vascular risk factors, prevalent cardiovascular disease events and restless legs syndrome. Results The mean age of the cohort 67.8 years. Restless legs syndrome prevalence was 7.5% and increased significantly with age. Diabetes significantly increased the odds (OR: 1.41, 95%CI: 1.21–1.65), while frequent exercise (OR: 0.78, 95%CI: 0.67–0.91) and alcohol consumption of one or more drinks per day (OR: 0.80, 95%CI: 0.69–0.92) significantly reduced the odds of restless legs syndrome in multivariable-adjusted models. Prevalent stroke showed an increased multivariable-adjusted OR of 1.40 (1.05–1.86) while men with prevalent myocardial infarction had a decreased OR of 0.73 (0.55–0.97) for restless legs syndrome. Conclusions The restless legs syndrome prevalence among US male physicians is similar to men of the same age group in other western countries. A history of diabetes is the most consistent risk factor associated with restless legs syndrome. Prevalent stroke and myocardial infarction are related to restless legs

  6. Substrate Stiffness Controls Osteoblastic and Chondrocytic Differentiation of Mesenchymal Stem Cells without Exogenous Stimuli.

    Directory of Open Access Journals (Sweden)

    Rene Olivares-Navarrete

    Full Text Available Stem cell fate has been linked to the mechanical properties of their underlying substrate, affecting mechanoreceptors and ultimately leading to downstream biological response. Studies have used polymers to mimic the stiffness of extracellular matrix as well as of individual tissues and shown mesenchymal stem cells (MSCs could be directed along specific lineages. In this study, we examined the role of stiffness in MSC differentiation to two closely related cell phenotypes: osteoblast and chondrocyte. We prepared four methyl acrylate/methyl methacrylate (MA/MMA polymer surfaces with elastic moduli ranging from 0.1 MPa to 310 MPa by altering monomer concentration. MSCs were cultured in media without exogenous growth factors and their biological responses were compared to committed chondrocytes and osteoblasts. Both chondrogenic and osteogenic markers were elevated when MSCs were grown on substrates with stiffness <10 MPa. Like chondrocytes, MSCs on lower stiffness substrates showed elevated expression of ACAN, SOX9, and COL2 and proteoglycan content; COMP was elevated in MSCs but reduced in chondrocytes. Substrate stiffness altered levels of RUNX2 mRNA, alkaline phosphatase specific activity, osteocalcin, and osteoprotegerin in osteoblasts, decreasing levels on the least stiff substrate. Expression of integrin subunits α1, α2, α5, αv, β1, and β3 changed in a stiffness- and cell type-dependent manner. Silencing of integrin subunit beta 1 (ITGB1 in MSCs abolished both osteoblastic and chondrogenic differentiation in response to substrate stiffness. Our results suggest that substrate stiffness is an important mediator of osteoblastic and chondrogenic differentiation, and integrin β1 plays a pivotal role in this process.

  7. Beneficial effects of exercise on subendothelial matrix stiffness are short-lived.

    Science.gov (United States)

    Kohn, Julie; Bordeleau, Francois; Miller, Joseph; Watkins, Hannah; Modi, Shweta; Ma, Jenny; Azar, Julian; Putnam, David; Reinhart-King, Cynthia

    2018-03-12

    Aerobic exercise helps to maintain cardiovascular health in part by mitigating age-induced arterial stiffening. However, the long-term effects of exercise regimens on aortic stiffness remain unknown, especially in the intimal extracellular matrix layer known as the subendothelial matrix. To examine how the stiffness of the subendothelial matrix changes following exercise cessation, mice were exposed to an 8-week swimming regimen followed by an 8-week sedentary rest period. Whole vessel and subendothelial matrix stiffness were measured after both the exercise and rest periods. After swimming, whole vessel and subendothelial matrix stiffness decreased, and after 8 weeks of rest, these values returned to baseline. Within the same time frame, the collagen content in the intima layer and the presence of advanced glycation end products in the whole vessel were also affected by the exercise and the rest periods. Overall, our data indicate that consistent exercise is necessary for maintaining compliance in the subendothelial matrix.

  8. Pulsed electromagnetic field therapy for management of osteoarthritis-related pain, stiffness and physical function: clinical experience in the elderly.

    Science.gov (United States)

    Iannitti, Tommaso; Fistetto, Gregorio; Esposito, Anna; Rottigni, Valentina; Palmieri, Beniamino

    2013-01-01

    Pulsed electromagnetic field (PEMF) therapy has shown promising therapeutic effectiveness on bone- and cartilage-related pathologies, being also safe for management of knee osteoarthritis. The aim of this study was to investigate the clinical efficacy of a PEMF device for management of knee osteoarthritis in elderly patients. A total of 33 patients were screened, and 28 patients, aged between 60 and 83 and affected by bilateral knee osteoarthritis, were enrolled in this study. They received PEMF therapy on the right leg for a total of three 30-minute sessions per week for a period of 6 weeks, while the left leg did not receive any treatment and served as control. An intravenous drip containing ketoprofen, sodium clodronate, glucosamine sulfate, calcitonin, and ascorbic acid, for a total volume of 500 mL, was administered during PEMF therapy. At baseline and 3 months post-PEMF therapy, Visual Analog Scale (VAS) was used to assess knee pain and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) was used to measure knee pain, stiffness and physical function. Changes in VAS and WOMAC scores were calculated for both knees as baseline minus post-treatment. A two sample Student's t-test, comparing change in knee-related VAS pain for PEMF-treated leg (49.8 ± 2.03) vs control leg (11 ± 1.1), showed a significant difference in favor of PEMF therapy (P PEMF-treated leg (8.5 ± 0.4, 3.5 ± 0.2, 38.5 ± 2.08, respectively) vs control leg (2.6 ± 0.2; 1.6 ± 0.1; 4.5 ± 0.5 respectively), also showed a significant difference in favor of PEMF therapy (P PEMF therapy improves pain, stiffness and physical function in elderly patients affected by knee osteoarthritis.

  9. [Etiological diagnosis of leg ulcers].

    Science.gov (United States)

    Debure, Clélia

    2010-09-20

    Etiological diagnosis of leg ulcers must be the first step of treatment, even if we know that veinous disease is often present. We can build a clinical decisional diagram, which helps us to understand and not forget the other causes of chronic wounds and choose some basic examination, like ultrasound and histological findings. This diagnosis helps to choose the right treatment in order to cure even the oldest venous ulcers. Educational programs should be improved to prevent recurrence.

  10. Thick legs - not always lipedema.

    Science.gov (United States)

    Reich-Schupke, Stefanie; Altmeyer, Peter; Stücker, Markus

    2013-03-01

    Due to its increased presence in the press and on television, the diagnosis of lipedema is on the way to becoming a trendy diagnosis for those with thick legs. Despite this, one must recognize that lipedema is a very rare disease. It is characterized by disproportional obesity of the extremities, especially in the region of the hip and the legs, hematoma development after minimal trauma, and increased pressure-induced or spontaneous pain. Aids for making the correct diagnosis are (duplex) sonography, the waist-hip index or the waist-height index and lymphoscintigraphy. Important differential diagnoses are constitutional variability of the legs, lipohypertrophy in obesity, edema in immobility, edema in chronic venous insufficiency and rheumatic diseases. The symptom-based therapy of lipedema consists of conservative (compression, manual lymphatic drainage, exercise) and surgical treatments (liposuction). Until now there is no curative therapy. Obesity is an important risk factor for the severity and prognosis of lipedema. Further studies for a better understanding of the pathogenesis of lipedema and in the end possible curative treatments are urgently needed. © The Authors | Journal compilation © Blackwell Verlag GmbH, Berlin.

  11. Lung function is associated with arterial stiffness in children.

    Directory of Open Access Journals (Sweden)

    Julian G Ayer

    Full Text Available BACKGROUND: In older adults, an independent association exists between impaired lung function and cardiovascular disease. This interaction might be related to the effects of aging and/or smoking. In order to explore possible childhood antecedents to this association, we hypothesized that decreased lung function and vascular stiffness might be related, in early life. OBJECTIVE: To determine the relationship between lung function and carotid augmentation index (AIx, a measure of vascular stiffness, in 8-year old children. METHODS: Data on brachial blood pressure, lung function (FEV(1, FVC, FEV(1/FVC, obtained by spirometry and carotid AIx75 (AIx standardised to an arbitrary heart rate of 75 beats per minute, obtained by applanation tonometry was available in 249 community-based 8-year old children. These healthy children had been subjects in a randomised controlled trial of two interventions (omega-3 fatty acid supplementation and house-dust mite avoidance to prevent asthma. Smoking in pregnancy and childhood environmental tobacco smoke (ETS exposure was prospectively collected by questionnaire. The association between lung function and carotid AIx75 was assessed in multivariate models that included sex, height, smoking status during pregnancy, ETS exposure and randomisation groups (house dust mite avoidance and dietary intervention as covariates. RESULTS: In the fully adjusted models, Carotid AIx75 was independently associated with FEV1 (standardised β = -0.17,b = -6.72, partial R(2 = .02, p = 0.03, FVC (standardised β = -0.29, b = -9.31, partial R(2 = 0.04, p<0.001 and FEV1/FVC (standardised β = .13, b = 18.4, partial R(2 = 0.02, p = 0.04. CONCLUSION: Lower lung volumes are associated with increased vascular stiffness at an early age. The interaction between lung function and vascular stiffness may thus represent more than just age-related alterations in both the pulmonary and vascular systems.

  12. Single motor–variable stiffness actuator using bistable switching mechanisms for independent motion and stiffness control

    NARCIS (Netherlands)

    Groothuis, Stefan; Carloni, Raffaella; Stramigioli, Stefano

    This paper presents a proof of concept of a variable stiffness actuator (VSA) that uses only one (high power) input motor. In general, VSAs use two (high power) motors to be able to control both the output position and the output stiffness, which possibly results in a heavy, and bulky system. In

  13. Post-traumatic knee stiffness: surgical techniques.

    Science.gov (United States)

    Pujol, N; Boisrenoult, P; Beaufils, P

    2015-02-01

    Post-traumatic knee stiffness and loss of range of motion is a common complication of injuries to the knee area. The causes of post-traumatic knee stiffness can be divided into flexion contractures, extension contractures, and combined contractures. Post-traumatic stiffness can be due to the presence of dense intra-articular adhesions and/or fibrotic transformation of peri-articular structures. Various open and arthroscopic surgical treatments are possible. A precise diagnosis and understanding of the pathology is mandatory prior to any surgical treatment. Failure is imminent if all pathologies are not addressed correctly. From a general point of view, a flexion contracture is due to posterior adhesions and/or anterior impingement. On the other hand, extension contractures are due to anterior adhesions and/or posterior impingement. This overview will describe the different modern surgical techniques for treating post-traumatic knee stiffness. Any bony impingements must be treated before soft tissue release is performed. Intra-articular stiff knees with a loss of flexion can be treated by an anterior arthroscopic arthrolysis. Extra-articular pathology causing a flexion contracture can be treated by open or endoscopic quadriceps release. Extension contractures can be treated by arthroscopic or open posterior arthrolysis. Postoperative care (analgesia, rehabilitation) is essential to maintaining the range of motion obtained intra-operatively. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  14. Estimative of relative stiffness of the exudate gum polysaccharides

    International Nuclear Information System (INIS)

    Oliveira, Marilia A.; Paula, Regina C.M.

    2001-01-01

    The Smidsrod empirical stiffness parameter (B) of A. occidentale and A. lebbeck gum were determined using the correlation of intrinsic viscosity [η] with ionic strength. The B value of 0.204 and 0.193 found respectively for A. occidentale and A. lebbeck suggests a flexible the molecule. The ionic strength has a greater influence on the [η]. The decrease of [η] increase of I, from 0.01 M to 0.1 M of NaCl, is higher for A. lebbeck (89%) than for A. occidentale (19%). (author)

  15. A Novel Variable Stiffness Mechanism Capable of an Infinite Stiffness Range and Unlimited Decoupled Output Motion

    Directory of Open Access Journals (Sweden)

    Stefan Groothuis

    2014-06-01

    Full Text Available In this paper, a novel variable stiffness mechanism is presented, which is capable of achieving an output stiffness with infinite range and an unlimited output motion, i.e., the mechanism output is completely decoupled from the rotor motion, in the zero stiffness configuration. The mechanism makes use of leaf springs, which are engaged at different positions by means of two movable supports, to realize the variable output stiffness. The Euler–Bernoulli leaf spring model is derived and validated through experimental data. By shaping the leaf springs, it is shown that the stiffness characteristic of the mechanism can be changed to fulfill different application requirements. Alternative designs can achieve the same behavior with only one leaf spring and one movable support pin.

  16. Epilepsy and restless legs syndrome.

    Science.gov (United States)

    Geyer, James D; Geyer, Emery E; Fetterman, Zachary; Carney, Paul R

    2017-03-01

    Restless legs syndrome (RLS) is a common neurological movement disorder occurring in approximately 10% of the general population. The prevalence of moderately severe RLS is 2.7% overall (3.7% for women and 1.7% for men). Epilepsy is also a common neurological disorder with significant associated morbidity and impact on quality of life. We evaluated the severity and frequency of primary RLS in patients with localization-related temporal lobe epilepsy (TLE) and investigated the role of prodromal RLS symptoms as a warning sign and lateralizing indicator. All epilepsy patients seen in the outpatient clinic were screened for movement disorders from 2005 to 2015. Ninety-eight consecutive patients with localization-related TLE (50 right TLE and 48 left TLE) who met inclusion criteria were seen in the outpatient clinic. The control group consisted of 50 individuals with no history or immediate family history of epilepsy. Each patient was evaluated with the International Restless Legs Study Group (IRLSSG) questionnaire, NIH RLS diagnostic criteria, ferritin level, and comprehensive sleep screening including polysomnography. Furthermore, patients with obstructive sleep apnea or a definite cause of secondary restless legs syndrome such as low serum ferritin or serum iron levels were also excluded from the study. There was a significant association between the type of epilepsy and whether or not patients had RLS χ 2 (1)=10.17, prestlessness was typically described as moderately severe. The RLS symptoms were more common and somewhat more severe in the right TLE group than the left TLE group. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Calculation of shear stiffness in noise dominated magnetic resonance elastography data based on principal frequency estimation

    Energy Technology Data Exchange (ETDEWEB)

    McGee, K P; Lake, D; Mariappan, Y; Manduca, A; Ehman, R L [Department of Radiology, Mayo Clinic College of Medicine, 200 First Street, SW, Rochester, MN 55905 (United States); Hubmayr, R D [Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Mayo Clinic College of Medicine, 200 First Street, SW, Rochester, MN 55905 (United States); Ansell, K, E-mail: mcgee.kiaran@mayo.edu [Schaeffer Academy, 2700 Schaeffer Lane NE, Rochester, MN 55906 (United States)

    2011-07-21

    Magnetic resonance elastography (MRE) is a non-invasive phase-contrast-based method for quantifying the shear stiffness of biological tissues. Synchronous application of a shear wave source and motion encoding gradient waveforms within the MRE pulse sequence enable visualization of the propagating shear wave throughout the medium under investigation. Encoded shear wave-induced displacements are then processed to calculate the local shear stiffness of each voxel. An important consideration in local shear stiffness estimates is that the algorithms employed typically calculate shear stiffness using relatively high signal-to-noise ratio (SNR) MRE images and have difficulties at an extremely low SNR. A new method of estimating shear stiffness based on the principal spatial frequency of the shear wave displacement map is presented. Finite element simulations were performed to assess the relative insensitivity of this approach to decreases in SNR. Additionally, ex vivo experiments were conducted on normal rat lungs to assess the robustness of this approach in low SNR biological tissue. Simulation and experimental results indicate that calculation of shear stiffness by the principal frequency method is less sensitive to extremely low SNR than previously reported MRE inversion methods but at the expense of loss of spatial information within the region of interest from which the principal frequency estimate is derived.

  18. Quinine for Nocturnal Leg Cramps

    Science.gov (United States)

    Man-Son-Hing, Malcolm; Wells, George; Lau, Anita

    1998-01-01

    OBJECTIVE With respect to the use of quinine for the treatment of nocturnal leg cramps, to determine whether the findings of a previously performed meta-analysis of published data are altered with the addition of unpublished data, and whether publication bias is present in this area. DESIGN A meta-analysis of eight (four published and four unpublished) randomized, double-blind, placebo-controlled trials, seven of which had a crossover design. SETTING Randomized trials that were available as of July 1997. SUBJECTS Ambulatory patients (659) who suffered from regular nocturnal leg cramps. MAIN RESULTS When individual patient data from all crossover studies were pooled, persons had 3.60 (95% confidence interval [CI] 2.15, 5.05) fewer cramps in a 4-week period when taking quinine compared with placebo. This compared with an estimate of 8.83 fewer cramps (95% CI 4.16, 13.49) from pooling published studies alone. The corresponding relative risk reductions were 21% (95% CI 12%, 30%) and 43% (95% CI 21%, 65%), respectively. Compared with placebo, the use of quinine was associated with an increased incidence of side effects, particularly tinnitus. Publication bias is present in the reporting of the efficacy of quinine for this indication, as almost all published studies reported larger estimates of its efficacy than did unpublished studies. CONCLUSIONS This study confirms that quinine is efficacious in the prevention of nocturnal leg cramps. However, its benefit may not be as large as reported from the pooling of published studies alone. Given the side effect profile of quinine, nonpharmacologic therapy (e.g., regular passive stretching of the affected muscle) is the best first-line treatment. For persons who find this ineffective and whose quality of life is significantly affected, a trial of quinine is warranted. Prescribing physicians must closely monitor the risks and benefits in individual patients. Publication bias is present in this area even though there is

  19. Postural stability deficits during the transition from double-leg stance to single-leg stance in anterior cruciate ligament reconstructed subjects.

    Science.gov (United States)

    Dingenen, Bart; Janssens, Luc; Claes, Steven; Bellemans, Johan; Staes, Filip F

    2015-06-01

    The goal of this study was to evaluate postural stability during the transition from double-leg stance (DLS) to single-leg stance (SLS) in anterior cruciate ligament reconstructed (ACLR) (n=20) and non-injured control subjects (n=20). All ACLR subjects had fully returned to their pre-injury sport participation. Both groups were similar for age, gender, height, weight, body mass index and activity level. Spatiotemporal center of pressure outcomes of both legs of each subject were measured during the transition from DLS to SLS in eyes open and eyes closed conditions. Movement speed was standardized. The center of pressure displacement after a new stability point was reached during the SLS phase was significantly increased in the ACLR group compared to the control group in the eyes closed condition (P=.001). No significant different postural stability outcomes were found between the operated and non-operated legs. In conclusion, the ACLR group showed postural stability deficits, indicating that these persons may have a decreased ability to stabilize their body after the internal postural perturbation created by the transition from DLS to SLS. The non-operated leg may not be the best reference when evaluating postural stability of the operated leg after ACLR, as no differences were found between legs. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. An acoustic startle alters knee joint stiffness and neuromuscular control.

    Science.gov (United States)

    DeAngelis, A I; Needle, A R; Kaminski, T W; Royer, T R; Knight, C A; Swanik, C B

    2015-08-01

    Growing evidence suggests that the nervous system contributes to non-contact knee ligament injury, but limited evidence has measured the effect of extrinsic events on joint stability. Following unanticipated events, the startle reflex leads to universal stiffening of the limbs, but no studies have investigated how an acoustic startle influences knee stiffness and muscle activation during a dynamic knee perturbation. Thirty-six individuals were tested for knee stiffness and muscle activation of the quadriceps and hamstrings. Subjects were seated and instructed to resist a 40-degree knee flexion perturbation from a relaxed state. During some trials, an acoustic startle (50 ms, 1000 Hz, 100 dB) was applied 100 ms prior to the perturbation. Knee stiffness, muscle amplitude, and timing were quantified across time, muscle, and startle conditions. The acoustic startle increased short-range (no startle: 0.044 ± 0.011 N·m/deg/kg; average startle: 0.047 ± 0.01 N·m/deg/kg) and total knee stiffness (no startle: 0.036 ± 0.01 N·m/deg/kg; first startle 0.027 ± 0.02 N·m/deg/kg). Additionally, the startle contributed to decreased [vastus medialis (VM): 13.76 ± 33.6%; vastus lateralis (VL): 6.72 ± 37.4%] but earlier (VM: 0.133 ± 0.17 s; VL: 0.124 ± 0.17 s) activation of the quadriceps muscles. The results of this study indicate that the startle response can significantly disrupt knee stiffness regulation required to maintain joint stability. Further studies should explore the role of unanticipated events on unintentional injury. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Effect of static foot posture on the dynamic stiffness of foot joints during walking.

    Science.gov (United States)

    Sanchis-Sales, E; Sancho-Bru, J L; Roda-Sales, A; Pascual-Huerta, J

    2018-03-17

    The static foot posture has been related to the development of lower limb injuries. This study aimed to investigate the dynamic stiffness of foot joints during gait in the sagittal plane to understand the role of the static foot posture in the development of injuries. Seventy healthy adult male subjects with different static postures, assessed by the Foot Posture Index (FPI) (30 normal, 20 highly pronated and 20 highly supinated), were recruited. Kinematic and kinetic data were recorded using an optical motion capture system and a pressure platform, and dynamic stiffness at the different stages of the stance was calculated from the slopes of the linear regression on the flexion moment-angle curves. The effect of foot type on dynamic stiffness and on ranges of motion and moments was analysed using ANOVAs and post-hoc tests, and linear correlation between dynamic stiffness and FPI was also tested. Highly pronated feet showed a significantly smaller range of motion at the ankle and metatarsophalangeal joints and also a larger range of moments at the metatarsophalangeal joint than highly supinated feet. Dynamic stiffness during propulsion was significantly greater at all foot joints for highly pronated feet, with positive significant correlations with the squared FPI. Highly supinated feet showed greater dynamic stiffness than normal feet, although to a lesser extent. Highly pronated feet during normal gait experienced the greatest decrease in the dorsiflexor moments during propulsion, normal feet being the most balanced regarding work generated and absorbed. Extreme static foot postures show greater dynamic stiffness during propulsion and greater absorbed work, which increases the risk of developing injuries. The data presented may be used when designing orthotics or prostheses, and also when planning surgery that modifies joint stiffness. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Design and Testing of a Dynamically-Tuned Magnetostrictive Spring with Electrically-Controlled Stiffness

    Science.gov (United States)

    Scheidler, Justin; Asnani, Vivake M.; Dapino, Marcelo J.

    2015-01-01

    This paper details the development of an electrically-controlled, variable-stiffness spring based on magnetostrictive materials. The device, termed a magnetostrictive Varispring, can be applied as a semi-active vibration isolator or switched stiffness vibration controller for reducing transmitted vibrations. The Varispring is designed using 1D linear models that consider the coupled electrical response, mechanically-induced magnetic diffusion, and the effect of internal mass on dynamic stiffness. Modeling results illustrate that a Terfenol-D-based Varispring has a rise time almost an order of magnitude smaller and a magnetic diffusion cut-off frequency over two orders of magnitude greater than a Galfenol-based Varispring. The results motivate the use of laminated Terfenol-D rods for a greater stiffness tuning range and increased bandwidth. The behavior of a prototype Varispring is examined under vibratory excitation up to 6 MPa and 25 Hz using a dynamic load frame. For this prototype, stiffness is indirectly varied by controlling the excitation current. Preliminary measurements of continuous stiffness tuning via sinusoidal currents up to 1 kHz are presented. The measurements demonstrate that the Young's modulus of the Terfenol-D rod inside the Varispring can be continuously varied by up to 21.9 GPa. The observed stiffness tuning range is relatively constant up to 500 Hz, but significantly decreases thereafter. The stiffness tuning range can be greatly increased by improving the current and force control such that a more consistent current can be applied and the Varispring can be accurately tested at a more optimal bias stress.

  3. Plant fibre composites - porosity and stiffness

    DEFF Research Database (Denmark)

    Madsen, Bo; Thygesen, Anders; Lilholt, Hans

    2009-01-01

    of the composites with their mechanical properties. The fibre weight fraction is used as an independent parameter to calculate the complete volumetric composition. A maximum obtainable stiffness of the composites is calculated at a certain transition fibre weight fraction, which is characterised by a best possible...... combination of high fibre volume fraction and low porosity. The model is validated with experimental data from the literature on several types of composites. A stiffness diagram is presented to demonstrate that the calculations can be used for tailoring and design of composites with a given profile...... of properties. (C) 2009 Elsevier Ltd. All rights reserved....

  4. Maximum-speed curve-running biomechanics of sprinters with and without unilateral leg amputations.

    Science.gov (United States)

    Taboga, Paolo; Kram, Rodger; Grabowski, Alena M

    2016-03-01

    On curves, non-amputees' maximum running speed is slower on smaller radii and thought to be limited by the inside leg's mechanics. Similar speed decreases would be expected for non-amputees in both counterclockwise and clockwise directions because they have symmetric legs. However, sprinters with unilateral leg amputation have asymmetric legs, which may differentially affect curve-running performance and Paralympic competitions. To investigate this and understand the biomechanical basis of curve running, we compared maximum curve-running (radius 17.2 m) performance and stride kinematics of six non-amputee sprinters and 11 sprinters with a transtibial amputation. Subjects performed randomized, counterbalanced trials: two straight, two counterclockwise curves and two clockwise curves. Non-amputees and sprinters with an amputation all ran slower on curves compared with straight running, but with different kinematics. Non-amputees ran 1.9% slower clockwise compared with counterclockwise (Pleg on the inside compared with the outside of the curve (Pleg on the inside. During curve running, non-amputees and athletes with an amputation had longer contact times with their inside compared with their outside leg, suggesting that the inside leg limits performance. For sprinters with an amputation, the prolonged contact times of the affected versus unaffected leg seem to limit maximum running speed during both straight running and running on curves with the affected leg on the inside. © 2016. Published by The Company of Biologists Ltd.

  5. EVALUATION OF HEALING EFFECTS OF NEW HERBAL FORMULATION ON VENOUS LEG ULCER: PILOT STUDY

    Directory of Open Access Journals (Sweden)

    Ivana Binić

    2011-06-01

    Full Text Available Venous leg ulcers represent a significant public health problem that will increase as the population ages. A wide variety of agents are available for the treatment of venous leg ulcers, including ointments and dressings. Numerous herbs and their extracts are potentially conducive to wound healing, including the ability to serve as an antimicrobial, antifungal, astringent and etc.The aim of the study was to establish the healing effects of herbal therapy on non-infected venous leg ulcers. The major components of the DermaplantG were extract of Allii bulbus, Hyperici herba and extract of Calendulae flos. In the study were included 18 patients with venous leg ulcers treated by DermaplantG herbal therapy. Our investigation focused on the five controls (baseline, 1st , 3rd, 5th 7th weeks of the parameters changes important for ulcer healing: wound surface area and reduction of venous leg ulcer score (fibrin deposits, exudation and eczema. Within-treatment analysis showed that, following DermaplantG herbal treatment, there was a significant decrease in surface leg ulcer and venous leg ulcer score after 7th treatment week (P < 0.05. The results of this pilot study demonstrate healing and antimicrobiologic efects of herbal therapy on non-infected venous leg ulcer.

  6. Gait Planning Research for an Electrically Driven Large-Load-Ratio Six-Legged Robot

    Directory of Open Access Journals (Sweden)

    Hong-Chao Zhuang

    2017-03-01

    Full Text Available Gait planning is an important basis for the walking of a legged robot. To improve the walking stability of multi-legged robots and to reduce the impact force between the foot and the ground, gait planning strategies are presented for an electrically driven large-load-ratio six-legged robot. First, the configuration and walking gait of the electrically driven large-load-ratio six-legged robot are designed. The higher-stable swing sequences of legs and typical walking modes are respectively obtained. Based on the Denavit–Hartenberg (D–H method, the analyses of the forward and inverse kinematics are implemented. The mathematical models of the articulated rotation angles are respectively established. In view of the buffer device installed at the end of shin to decrease the impact force between the foot and the ground, an initial lift height of the leg is brought into gait planning when the support phase changes into the transfer phase. The mathematical models of foot trajectories are established. Finally, a prototype of the electrically driven large-load-ratio six-legged robot is developed. The experiments of the prototype are carried out regarding the aspects of the walking speed and surmounting obstacle. Then, the reasonableness of gait planning is verified based on the experimental results. The proposed strategies of gait planning lay the foundation for effectively reducing the foot–ground impact force and can provide a reference for other large-load-ratio multi-legged robots.

  7. Leg fluid accumulation during prolonged sitting.

    Science.gov (United States)

    Vena, Daniel; Rubianto, Jonathan; Popovic, Milos; Yadollahi, Azadeh

    2016-08-01

    The accumulation of fluid in the legs due to sedentariness can be a health risk in extreme cases. Negative health impacts associated with leg fluid accumulation include leg edema and risk of blood clots. Furthermore, fluid accumulating in the legs is accompanied by fluid shift into the upper body which is also associated with health risks such as: increased blood pressure when lying down, respiratory problems in people with heart failure, and increased sleep apnea. Understanding the pattern by which fluid accumulates in the legs can aid in the development of devices for reducing leg fluid accumulation. The purpose of this study was to characterize the time course of fluid accumulation over a two-and-half-hour seated period. Non-obese participants with sleep apnea and no other co-morbidities were included in the sample as part of a larger study. Leg fluid was measured continuously using a method of bioelectrical impedance. Participants were first asked to lie supine for 30 minutes as a washout, and then sat with their legs still for two and a half hours. The main finding of this study is that the pattern of leg fluid accumulation differed in the first 45 minutes compared to the latter 105 minutes. In the first 45 minutes, fluid accumulated according to first order exponential function. In the latter period, fluid accumulated according to a linear function. The initial exponential accumulation is likely due to the large increase in capillary pressure caused by rapid blood flow into the legs due to gravity, leading to substantial filtration of blood plasma into the tissue spaces. The latter linear portion likely represents continued slow filtration of fluid out of the vasculature and into the tissue spaces. This is the first study to show that fluid accumulation in the legs is a combination of an exponential and linear functions. The linear increase identifies that there is no foreseeable point in which leg fluid stops accumulating while sitting for prolonged periods.

  8. In vivo Evaluation of Patellar Tendon Stiffness in Individuals with Patellofemoral Pain Syndrome

    Directory of Open Access Journals (Sweden)

    Hsin-Yi Liu

    2008-01-01

    Full Text Available The objective of this study was to utilise an ultrasonic technique to assess the effect of patellofemoral pain syndrome (PFPS on the mechanical properties of the patellar tendon. Seven subjects with PFPS and seven matched control subjects volunteered to participate in this study. Subjects were asked to perform isometric maximal voluntary contractions of the knee extensors while their knee extension torque was monitored and the displacement of the patellar tendon was recorded with an ultrasonic system. Our results showed significantly lower tendon stiffness (by ∼30% in the PFPS subjects. Although tendon secant modulus was lower by 34% in the PFPS subjects, the difference was not statistically significant. Therefore, we conclude that the ultrasonic technique was able to detect a decrease in the structural stiffness of the patellar tendon associated with PFPS. The decrease in tendon stiffness was moderately correlated with the length of symptoms in these individuals.

  9. Restless legs syndrome and periodic leg movements in patients with movement disorders: Specific considerations.

    Science.gov (United States)

    Högl, Birgit; Stefani, Ambra

    2017-05-01

    Restless legs syndrome is a frequent neurological disorder with potentially serious and highly distressing treatment complications. The role and potential implications of periodic leg movements during sleep range from being a genetic risk marker for restless legs syndrome to being a cardiovascular risk factor. The diagnosis of restless legs syndrome in patients with daytime movement disorders is challenging and restless legs syndrome needs to be differentiated from other sleep-related movement disorders. This article provides an update on the diagnosis of restless legs syndrome as an independent disorder and the role of periodic leg movements and reviews the association of restless legs syndrome with Parkinson's disease and other movement disorders. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.

  10. Model-Based Experimental Development of Passive Compliant Robot Legs from Fiberglass Composites

    Directory of Open Access Journals (Sweden)

    Shang-Chang Lin

    2015-01-01

    Full Text Available We report on the methodology of developing compliant, half-circular, and composite robot legs with designable stiffness. First, force-displacement experiments on flat cantilever composites made by one or multifiberglass cloths are executed. By mapping the cantilever mechanics to the virtual spring model, the equivalent elastic moduli of the composites can be derived. Next, by using the model that links the curved beam mechanics back to the virtual spring, the resultant stiffness of the composite in a half-circular shape can be estimated without going through intensive experimental tryouts. The overall methodology has been experimentally validated, and the fabricated composites were used on a hexapod robot to perform walking and leaping behaviors.

  11. Increased Stiffness in Aged Skeletal Muscle Impairs Muscle Progenitor Cell Proliferative Activity.

    Directory of Open Access Journals (Sweden)

    Grégory Lacraz

    Full Text Available Skeletal muscle aging is associated with a decreased regenerative potential due to the loss of function of endogenous stem cells or myogenic progenitor cells (MPCs. Aged skeletal muscle is characterized by the deposition of extracellular matrix (ECM, which in turn influences the biomechanical properties of myofibers by increasing their stiffness. Since the stiffness of the MPC microenvironment directly impacts MPC function, we hypothesized that the increase in muscle stiffness that occurs with aging impairs the behavior of MPCs, ultimately leading to a decrease in regenerative potential.We showed that freshly isolated individual myofibers from aged mouse muscles contain fewer MPCs overall than myofibers from adult muscles, with fewer quiescent MPCs and more proliferative and differentiating MPCs. We observed alterations in cultured MPC behavior in aged animals, where the proliferation and differentiation of MPCs were lower and higher, respectively. These alterations were not linked to the intrinsic properties of aged myofibers, as shown by the similar values for the cumulative population-doubling values and fusion indexes. However, atomic force microscopy (AFM indentation experiments revealed a nearly 4-fold increase in the stiffness of the MPC microenvironment. We further showed that the increase in stiffness is associated with alterations to muscle ECM, including the accumulation of collagen, which was correlated with higher hydroxyproline and advanced glycation end-product content. Lastly, we recapitulated the impaired MPC behavior observed in aging using a hydrogel substrate that mimics the stiffness of myofibers.These findings provide novel evidence that the low regenerative potential of aged skeletal muscle is independent of intrinsic MPC properties but is related to the increase in the stiffness of the MPC microenvironment.

  12. Shake a tail feather: the evolution of the theropod tail into a stiff aerodynamic surface.

    Directory of Open Access Journals (Sweden)

    Michael Pittman

    Full Text Available Theropod dinosaurs show striking morphological and functional tail variation; e.g., a long, robust, basal theropod tail used for counterbalance, or a short, modern avian tail used as an aerodynamic surface. We used a quantitative morphological and functional analysis to reconstruct intervertebral joint stiffness in the tail along the theropod lineage to extant birds. This provides new details of the tail's morphological transformation, and for the first time quantitatively evaluates its biomechanical consequences. We observe that both dorsoventral and lateral joint stiffness decreased along the non-avian theropod lineage (between nodes Theropoda and Paraves. Our results show how the tail structure of non-avian theropods was mechanically appropriate for holding itself up against gravity and maintaining passive balance. However, as dorsoventral and lateral joint stiffness decreased, the tail may have become more effective for dynamically maintaining balance. This supports our hypothesis of a reduction of dorsoventral and lateral joint stiffness in shorter tails. Along the avian theropod lineage (Avialae to crown group birds, dorsoventral and lateral joint stiffness increased overall, which appears to contradict our null expectation. We infer that this departure in joint stiffness is specific to the tail's aerodynamic role and the functional constraints imposed by it. Increased dorsoventral and lateral joint stiffness may have facilitated a gradually improved capacity to lift, depress, and swing the tail. The associated morphological changes should have resulted in a tail capable of producing larger muscular forces to utilise larger lift forces in flight. Improved joint mobility in neornithine birds potentially permitted an increase in the range of lift force vector orientations, which might have improved flight proficiency and manoeuvrability. The tail morphology of modern birds with tail fanning capabilities originated in early ornithuromorph

  13. Multiple-step model-experiment matching allows precise definition of dynamical leg parameters in human running.

    Science.gov (United States)

    Ludwig, C; Grimmer, S; Seyfarth, A; Maus, H-M

    2012-09-21

    The spring-loaded inverted pendulum (SLIP) model is a well established model for describing bouncy gaits like human running. The notion of spring-like leg behavior has led many researchers to compute the corresponding parameters, predominantly stiffness, in various experimental setups and in various ways. However, different methods yield different results, making the comparison between studies difficult. Further, a model simulation with experimentally obtained leg parameters typically results in comparatively large differences between model and experimental center of mass trajectories. Here, we pursue the opposite approach which is calculating model parameters that allow reproduction of an experimental sequence of steps. In addition, to capture energy fluctuations, an extension of the SLIP (ESLIP) is required and presented. The excellent match of the models with the experiment validates the description of human running by the SLIP with the obtained parameters which we hence call dynamical leg parameters. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Whole-body vibration as a potential countermeasure for dynapenia and arterial stiffness

    Directory of Open Access Journals (Sweden)

    Arturo Figueroa

    2016-09-01

    Full Text Available Age-related decreases in muscle mass and strength are associated with decreased mobility, quality of life, and increased cardiovascular risk. Coupled with the prevalence of obesity, the risk of death becomes substantially greater. Resistance training (RT has a well-documented beneficial impact on muscle mass and strength in young and older adults, although the high-intensity needed to elicit these adaptations may have a detrimental or negligible impact on vascular function, specifically on arterial stiffness. Increased arterial stiffness is associated with systolic hypertension, left ventricular hypertrophy, and myocardial ischemia. Therefore, improvements of muscle strength and arterial function are important in older adults. Recently, whole-body vibration (WBV exercise, a novel modality of strength training, has shown to exhibit similar results on muscle strength as RT in a wide-variety of populations, with the greatest impact in elderly individuals with limited muscle function. Additionally, WBV training has been shown to have beneficial effects on vascular function by reducing arterial stiffness. This article reviews relevant publications reporting the effects of WBV on muscle strength and/or arterial stiffness. Findings from current studies suggest the use of WBV training as an alternative modality to traditional RT to countermeasure the age-related detriments in muscle strength and arterial stiffness in older adults.

  15. Restless legs syndrome mimicking S1 radiculopathy.

    Science.gov (United States)

    Zambelis, Th; Wolgamuth, B R; Papoutsi, S N; Economou, N T

    2016-01-01

    Α case of a chronic idiopathic form of a severe type of Restless Legs Syndrome (RLS), which developed during pregnancy and persisted after this, misdiagnosed for 34 years as radiculopathy S1, is reported. In spite of the thorough clinical and laboratory investigation, in addition to constant changes of the therapeutic approach, the diagnosis of S1 radiculopathy could not be confirmed, resulting in a chronic clinical course; the latter was characterized by relapses and remissions not attributed or linked in any way to the treatment (various types of). In fact, it was due to a routine workup in a sleep clinic, where the patient was referred because of a coincident chronic insomnia (Restless Legs Syndrome is a known and important cause of insomnia/chronic insomnia), which resulted in a proper diagnosis and treatment of this case. With the use of Restless Legs Syndrome appropriate treatment (Pramipexole 0.18 mg taken at bedtime, a dopaminergic agent and Level A recommended drug for Restless Legs Syndrome) an excellent response and immediate elimination of symptoms was achieved. Restless Legs Syndrome may present with a variety of symptoms (with the most prominent shortly being reported with the acronym URGE: Urge to move the legs usually associated with unpleasant leg sensations, Rest induces symptoms, Getting active brings relief, Evening and night deteriorate symptoms); given the fact that Restless Legs Syndrome presents with a great variety and heterogeneity of symptoms (mostly pain, dysesthesia and paresthesia), which may occur in several other diseases (the so called "RLS mimics"), proper diagnosis of Restless Legs Syndrome usually fails. Restless Legs Syndrome misinterpreted as S1 radiculopathy, to the best of our knowledge, has not been reported yet in the literature. Here, case history, clinical course and common RLS mimics are presented. Different forms of Restless Legs Syndrome manifestations, which are commonly -as in this case- misinterpreted due to their

  16. Parametric study of roof diaphragm stiffness requirements

    International Nuclear Information System (INIS)

    Jones, W.D.; Tenbus, M.A.

    1991-01-01

    A common assumption made in performing a dynamic seismic analysis for a building is that the roof/floor system is open-quotes rigidclose quotes. This assumption would appear to be reasonable for many of the structures found in nuclear power plants, since many of these structures are constructed of heavily reinforced concrete having floor/roof slabs at least two feet in thickness, and meet the code requirements for structural detailing for seismic design. The roofs of many Department of Energy (DOE) buildings at the Oak Ridge Y-12 Plant in Oak Ridge, Tennessee, have roofs constructed of either metal, precast concrete or gypsum plank deck overlaid with rigid insulation, tar and gravel. In performing natural phenomena hazard assessments for one such facility, it was assumed that the existing roof performed first as a flexible diaphragm (zero stiffness) and then, rigid (infinitely stiff). For the flexible diaphragm model it was determined that the building began to experience significant damage around 0.09 g's. For the rigid diaphragm model it was determined that no significant damage was observed below 0.20 g's. A Conceptual Design Report has been prepared for upgrading/replacing the roof of this building. The question that needed to be answered here was, open-quotes How stiff should the new roof diaphragm be in order to satisfy the rigid diaphragm assumption and, yet, be cost effective?close quotes. This paper presents a parametric study of a very simple structural system to show that the design of roof diaphragms needs to consider both strength and stiffness (frequency) requirements. This paper shows how the stiffness of a roof system affects the seismically induced loads in the lateral, vertical load resisting elements of a building and provides guidance in determining how open-quotes rigidclose quotes a roof system should be in order to accomplish a cost effective design

  17. Pulsed electromagnetic field therapy for management of osteoarthritis-related pain, stiffness and physical function: clinical experience in the elderly

    Directory of Open Access Journals (Sweden)

    Iannitti T

    2013-09-01

    Full Text Available Tommaso Iannitti,1,2 Gregorio Fistetto,2 Anna Esposito,2 Valentina Rottigni,2,3 Beniamino Palmieri2,3 1Department of Physiology, University of Kentucky Medical Center, Lexington, KY, USA; 2Poliambulatorio del Secondo Parere, Modena, Italy; 3Department of General Surgery and Surgical Specialties, University of Modena and Reggio Emilia Medical School, Surgical Clinic, Modena, Italy Background: Pulsed electromagnetic field (PEMF therapy has shown promising therapeutic effectiveness on bone- and cartilage-related pathologies, being also safe for management of knee osteoarthritis. Aim: The aim of this study was to investigate the clinical efficacy of a PEMF device for management of knee osteoarthritis in elderly patients. Materials and methods: A total of 33 patients were screened, and 28 patients, aged between 60 and 83 and affected by bilateral knee osteoarthritis, were enrolled in this study. They received PEMF therapy on the right leg for a total of three 30-minute sessions per week for a period of 6 weeks, while the left leg did not receive any treatment and served as control. An intravenous drip containing ketoprofen, sodium clodronate, glucosamine sulfate, calcitonin, and ascorbic acid, for a total volume of 500 mL, was administered during PEMF therapy. At baseline and 3 months post-PEMF therapy, Visual Analog Scale (VAS was used to assess knee pain and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC was used to measure knee pain, stiffness and physical function. Results: Changes in VAS and WOMAC scores were calculated for both knees as baseline minus post-treatment. A two sample Student’s t-test, comparing change in knee-related VAS pain for PEMF-treated leg (49.8 ± 2.03 vs control leg (11 ± 1.1, showed a significant difference in favor of PEMF therapy (P < 0.001. A two sample Student’s t-test comparing change in knee-related WOMAC pain, stiffness, and physical function for PEMF-treated leg (8.5 ± 0.4, 3.5 ± 0.2, 38

  18. Intensive treatment of leg lymphedema

    Directory of Open Access Journals (Sweden)

    Pereira de Godoy Jose

    2010-01-01

    Full Text Available Background: Despite of all the problems caused by lymphedema, this disease continues to affect millions of people worldwide. Thus, the identification of the most efficacious forms of treatment is necessary. Aim: The aim of this study was to evaluate a novel intensive outpatient treatment for leg lymphedema. Methods: Twenty-three legs of 19 patients were evaluated in a prospective randomized study. The inclusion criteria were patients with Grade II and III lymphedema, where the difference, measured by volumetry, between the affected limb below the knee and the healthy limb was greater than 1.5 kg. Intensive treatment was carried out for 6- to 8-h sessions in the outpatient clinic. Analysis of variance was utilized for statistical analysis with an alpha error of 5% (P-value < 0.05 being considered significant. Results: All limbs had significant reductions in size with the final mean loss being 81.1% of the volume of edema. The greatest losses occurred in the first week (P-value < 0.001. Losses of more than 90% of the lymphedema occurred in 9 (39.13% patients; losses of more than 80% in 13 (56.52%, losses of more than 70% in 17 (73.91% and losses of more than 50% were recorded for 95.65% of the patients; only 1 patient lost less than 50% (37.9% of the edema. Conclusion: The intensive treatment of lymphedema in the outpatient clinic can produce significant reductions in the volume of edema over a short period of time and can be recommended for any grade of lymphedema, in particular the more advanced degrees.

  19. Børns leg og eksperimenterende virksomhed

    DEFF Research Database (Denmark)

    Damgaard Warrer, Sarah; Broström, Stig

    Børns leg og eksperimenterende virksomhed er et rigt felt med mange perspektiver, indgangsvinkler og nuancer. I denne bog kædes leg og det eksperimenterende og skabende sammen som to gensidigt forbundne fænomener og belyses i pædagogisk og didaktisk perspektiv. Desuden beskrives potentialet i båd...

  20. Does experimental low back pain change posteroanterior lumbar spinal stiffness and trunk muscle activity? A randomized crossover study.

    Science.gov (United States)

    Wong, Arnold Y L; Parent, Eric C; Prasad, Narasimha; Huang, Christopher; Chan, K Ming; Kawchuk, Gregory N

    2016-05-01

    While some patients with low back pain demonstrate increased spinal stiffness that decreases as pain subsides, this observation is inconsistent. Currently, the relation between spinal stiffness and low back pain remains unclear. This study aimed to investigate the effects of experimental low back pain on temporal changes in posteroanterior spinal stiffness and concurrent trunk muscle activity. In separate sessions five days apart, nine asymptomatic participants received equal volume injections of hypertonic or isotonic saline in random order into the L3-L5 interspinous ligaments. Pain intensity, spinal stiffness (global and terminal stiffness) at the L3 level, and the surface electromyographic activity of six trunk muscles were measured before, immediately after, and 25-minute after injections. These outcome measures under different saline conditions were compared by generalized estimating equations. Compared to isotonic saline injections, hypertonic saline injections evoked significantly higher pain intensity (mean difference: 5.7/10), higher global (mean difference: 0.73N/mm) and terminal stiffness (mean difference: 0.58N/mm), and increased activity of four trunk muscles during indentation (Ppain subsided. While previous clinical research reported inconsistent findings regarding the association between spinal stiffness and low back pain, our study revealed that experimental pain caused temporary increases in spinal stiffness and concurrent trunk muscle co-contraction during indentation, which helps explain the temporal relation between spinal stiffness and low back pain observed in some clinical studies. Our results substantiate the role of spinal stiffness assessments in monitoring back pain progression. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Is chronic obstructive pulmonary disease associated with increased arterial stiffness?

    DEFF Research Database (Denmark)

    Janner, Julie H; McAllister, David A; Godtfredsen, Nina S

    2012-01-01

    We hypothesize that airflow limitation is associated with increasing arterial stiffness and that having COPD increases a non-invasive measure of arterial stiffness - the aortic augmentation index (AIx) - independently of other CVD risk factors....

  2. Active and Inactive Leg Hemodynamics during Sequential Single-Leg Interval Cycling.

    Science.gov (United States)

    Gordon, Nicole; Abbiss, Chris R; Ihsan, Mohammed; Maiorana, Andrew J; Peiffer, Jeremiah J

    2018-01-11

    Leg order during sequential single-leg cycling (i.e. exercising both legs independently within a single session) may affect local muscular responses potentially influencing adaptations. This study examined the cardiovascular and skeletal muscle hemodynamic responses during double-leg and sequential single-leg cycling. Ten young healthy adults (28 ± 6 y) completed six 1-min double-leg intervals interspersed with one minute of passive recovery and, on a separate occasion, 12 (six with one leg followed by six with the other leg) 1-min single-leg intervals interspersed with one minute of passive recovery. Oxygen consumption, heart rate, blood pressure, muscle oxygenation, muscle blood volume and power output were measured throughout each session. Oxygen consumption, heart rate and power output were not different between sets of single-leg intervals but the average of both sets was lower than the double-leg intervals. Mean arterial pressure was higher during double-leg compared with sequential single-leg intervals (115 ± 9 mmHg vs. 104 ± 9 mmHg; p<0.05) and higher during the initial compared with second set of single-leg intervals (108 ± 10 mmHg vs. 101 ± 10 mmHg; p<0.05). The increase in muscle blood volume from baseline was similar between the active single-leg and double-leg (267 ± 150 μM[BULLET OPERATOR]cm vs. 214 ± 169 μM[BULLET OPERATOR]cm; p=0.26). The pattern of change in muscle blood volume from the initial to second set of intervals was significantly different (p<0.05) when the leg was active in the initial (-52.3 ± 111.6%) compared with second set (65.1 ± 152.9%). These data indicate that the order in which each leg performs sequential single-leg cycling influences the local hemodynamic responses, with the inactive muscle influencing the stimulus experienced by the contralateral leg.

  3. Increased blood pressure and aortic stiffness among abusers of anabolic androgenic steroids

    DEFF Research Database (Denmark)

    Rasmussen, Jon J; Schou, Morten; Madsen, Per L

    2018-01-01

    BACKGROUND: Abuse of anabolic androgenic steroids (AAS) is prevalent among recreational athletes and adverse effects on blood pressure (BP) and arterial stiffness could be substantial. Testosterone decreases natriuretic peptides which are key components in BP-regulation and may impair BP...

  4. The stable stiffness triangle - drained sand during deformation cycles

    DEFF Research Database (Denmark)

    Sabaliauskas, Tomas; Ibsen, Lars Bo

    2017-01-01

    Cyclic, drained sand stiffness was observed using the Danish triaxial appa- ratus. New, deformation dependant soil property (the stable stiffness triangle) was detected. Using the the stable stiffness triangle, secant stiffness of drained sand was plausible to predict (and control) even during ir...... findings can find application in off-shore, seismic and other engi- neering practice, or inspire new branches of research and modelling wherever dynamic, cyclic or transient loaded sand is encountered....

  5. Effect of leg length on ROM, VJ and leg dexterity in dance.

    Science.gov (United States)

    Wyon, M A; Nevill, A M; Dekker, K; Brown, D D; Clarke, F; Pelly, J; Koutedakis, Y

    2010-09-01

    We investigated the associations between leg length and specific ballet movements in different skill groups. Volunteers were from an undergraduate dance programme (n=18), a pre-professional school (n=43) and from an elite classical ballet company (n=45). Individual data were collected for anthropometry, vertical jump, leg dexterity, and leg active and passive ROM. ANCOVA identified both main effects as significant with regard to vertical jump (gender Peffects with gender, skill or leg length. Active and passive range of motion noted gender (P=0.001) and skill (Peffects of leg length on fundamental ballet skills. The longer legs that benefit vertical jump have a negative influence on range of motion and leg dexterity except for highly skilled dancers, who through skill, seem to have overcome the effects of some of these dichotomies. Georg Thieme Verlag KG Stuttgart . New York.

  6. Effects of weight loss and insulin reduction on arterial stiffness in the SAVE trial

    Directory of Open Access Journals (Sweden)

    Hughes Timothy M

    2012-09-01

    Full Text Available Abstract Background Chronic arterial stiffness contributes to the negative health effects of obesity and insulin resistance, which include hypertension, stroke, and increased cardiovascular and all-cause mortality. Weight loss and improved insulin sensitivity are individually associated with improved central arterial stiffness; however, their combined effects on arterial stiffness are poorly understood. The purpose of this study was to determine how insulin levels modify the improvements in arterial stiffness seen with weight loss in overweight and obese young adults. Methods To assess the effects of weight loss and decreased fasting insulin on vascular stiffness, we studied 339 participants in the Slow the Adverse Effects of Vascular Aging (SAVE trial. At study entry, the participants were aged 20–45, normotensive, non-diabetic, and had a body-mass index of 25–39.9 kg/m2. Measures of pulse wave velocity (PWV in the central (carotid-femoral (cfPWV, peripheral (femoral-ankle (faPWV, and mixed (brachial-ankle (baPWV vascular beds were collected at baseline and 6 months. The effects of 6-month change in weight and insulin on measures of PWV were estimated using multivariate regression. Results After adjustment for baseline risk factors and change in systolic blood pressure, 6-month weight loss and 6-month change in fasting insulin independently predicted improvement in baPWV but not faPWV or cfPWV. There was a significant interaction between 6-month weight change and change in fasting insulin when predicting changes in baPWV (p baPWV. Conclusions Young adults with excess weight who both lower their insulin levels and lose weight see the greatest improvement in vascular stiffness. This improvement in vascular stiffness with weight loss and insulin declines may occur throughout the vasculature and may not be limited to individual vascular beds. Trial registration NCT00366990

  7. How Crouch Gait Can Dynamically Induce Stiff-Knee Gait

    NARCIS (Netherlands)

    Van der Krogt, M.M.; Bregman, D.J.J.; Wisse, M.; Doorenbosch, C.A.M.; Harlaar, J.; Collins, S.H.

    Children with cerebral palsy frequently experience foot dragging and tripping during walking due to a lack of adequate knee flexion in swing (stiff-knee gait). Stiff-knee gait is often accompanied by an overly flexed knee during stance (crouch gait). Studies on stiff-knee gait have mostly focused on

  8. How Crouch Gait Can Dynamically Induce Stiff-Knee Gait

    NARCIS (Netherlands)

    van der Krogt, M.M.; Bregman, D.J.J.; Wisse, M.; Doorenbosch, C.A.M.; Harlaar, J.

    2010-01-01

    Children with cerebral palsy frequently experience foot dragging and tripping during walking due to a lack of adequate knee flexion in swing (stiff-knee gait). Stiff-knee gait is often accompanied by an overly flexed knee during stance (crouch gait). Studies on stiff-knee gait have mostly focused on

  9. Leg length change after opening wedge and closing wedge high tibial osteotomy: A meta-analysis.

    Science.gov (United States)

    Kim, Jun-Ho; Kim, Hyun-Jung; Lee, Dae-Hee

    2017-01-01

    Theoretical considerations suggest that leg length increases after opening wedge high tibial osteotomy (HTO) and decreases after closing wedge HTO; however, in vivo studies have yielded conflicting results. This meta-analysis therefore assessed changes in leg length after opening wedge and closing wedge HTO. All studies comparing pre- and postoperative leg length in patients who underwent opening and/or closing wedge HTO were included. Two reviewers independently recorded data from each study in terms of sample size as well as preoperative and postoperative leg length of open wedge and/or closed wedge HTO groups. Four studies were included in the meta-analysis. Although pooled results showed leg length changes from before to after surgery were -6.93 mm (95% confidence interval [CI]: -17.53 to 3.67 mm; P = 0.20) in opening wedge HTO and 1.97 mm (95% CI: -7.13 to 11.07 mm; P = 0.67) in closing wedge HTO, respectively, these values were statistically not significant. However, the difference in the pooled mean leg length change from before to after surgery between opening wedge and closing wedge HTO was 8 mm, a difference that was significant (95% CI: 6.53 to 9.46 mm; Pleg length was not statistically significant for either opening or closing wedge HTO. However, leg length change from before to after surgery was 8 mm greater for opening wedge HTO than for closing wedge HTO.

  10. No influence of lower leg heating on central arterial pulse pressure in young men.

    Science.gov (United States)

    Kosaki, Keisei; Sugawara, Jun; Akazawa, Nobuhiko; Tanahashi, Koichiro; Kumagai, Hiroshi; Ajisaka, Ryuichi; Maeda, Seiji

    2015-07-01

    Central arterial pulse pressure (PP), a strong predictor of cardiovascular disease, mainly consists of an incident wave generated by left ventricular ejection and a late-arriving reflected wave emanating from the lower body. We have tested the hypothesis that a reduction in leg vascular tone by heat treatment of the lower leg attenuates the central arterial PP. Pressure and wave properties of the peripheral and central arteries were measured in eight young men before and after heat treatment of the lower leg (temperature approx. 43 °C) for 30 and 60 min, respectively. Following the lower leg heat trial, leg (femoral-ankle) pulse wave velocity (PWV) was significantly decreased, but aortic (carotid-femoral) PWV and parameters of wave reflection and carotid arterial PP did not change significantly. No significant changes were observed in these parameters in the control trial. These results suggest that the reduction in leg vascular tone induced by heat treatment of the lower leg may not affect wave reflection and central arterial PP in young men.

  11. The Stress and Stiffness Analysis of Diaphragm

    Directory of Open Access Journals (Sweden)

    Qu Dongyue

    2017-01-01

    Full Text Available Diaphragm coupling with its simple structure, small size, high reliability, which can compensate for its input and output displacement deviation by its elastic deformation, is widely used in aerospace, marine, and chemical etc. This paper uses the ANSYS software and its APDL language to analysis the stress distribution when the diaphragm under the load of torque, axial deviation, centrifugal force, angular deviation and multiple loads. We find that the value of maximum stress usually appears in the outer or inner transition region and the axial deviation has a greater influence to the distribution of the stress. Based on above, we got three kinds of stiffness for axial, angular and torque, which the stiffness of diaphragm is nearly invariable. The results can be regard as an important reference for design and optimization of diaphragm coupling.

  12. Contact stiffness of randomly rough surfaces.

    Science.gov (United States)

    Pohrt, Roman; Popov, Valentin L

    2013-11-21

    We investigate the contact stiffness of an elastic half-space and a rigid indenter with randomly rough surface having a power spectrum C2D(q)proportional q(-2H-2), where q is the wave vector. The range of H[symbol: see text] is studied covering a wide range of roughness types from white noise to smooth single asperities. At low forces, the contact stiffness is in all cases a power law function of the normal force with an exponent α. For H > 2, the simple Hertzian behavior is observed . In the range of 0 dimensional contact mechanics and the method of dimensionality reduction (MDR). The influence of the long wavelength roll-off is investigated and discussed.

  13. Lipedema is associated with increased aortic stiffness.

    Science.gov (United States)

    Szolnoky, G; Nemes, A; Gavallér, H; Forster, T; Kemény, L

    2012-06-01

    Lipedema is a disproportional obesity due to unknown pathomechanism. Its major hallmark is frequent hematoma formation related to increased capillary fragility and reduced venoarterial reflex. Beyond microangiopathy, both venous and lymphatic dysfunction have also been documented. However, arterial circulation in lipedema has not been examined, and therefore we explored aortic elastic properties by echocardiography. Fourteen women with and 14 without lipedema were included in the study. Each subject consented to blood pressure measurement, physical examination, and transthoracic echocardiography. Aortic stiffness index (beta), distensibility, and strain were evaluated from aortic diameter and blood pressure data. Mean systolic (30.0 +/- 3.2 vs. 25.5 +/- 3.6, P lipedema is characterized with increased aortic stiffness.

  14. Electrothermally Actuated Microbeams With Varying Stiffness

    KAUST Repository

    Tella, Sherif Adekunle

    2017-11-03

    We present axially loaded clamped-guided microbeams that can be used as resonators and actuators of variable stiffness, actuation, and anchor conditions. The applied axial load is implemented by U-shaped electrothermal actuators stacked at one of the beams edges. These can be configured and wired in various ways, which serve as mechanical stiffness elements that control the operating resonance frequency of the structures and their static displacement. The experimental results have shown considerable increase in the resonance frequency and mid-point deflection of the microbeam upon changing the end conditions of the beam. These results can be promising for applications requiring large deflection and high frequency tunability, such as filters, memory devices, and switches. The experimental results are compared to multi-physics finite-element simulations showing good agreement among them.

  15. Steerable Hopping Six-Legged Robot

    Science.gov (United States)

    Younse, Paulo; Aghazarian, Hrand

    2010-01-01

    The figure depicts selected aspects of a six-legged robot that moves by hopping and that can be steered in the sense that it can be launched into a hop in a controllable direction. This is a prototype of hopping robots being developed for use in scientific exploration of rough terrain on remote planets that have surface gravitation less than that of Earth. Hopping robots could also be used on Earth, albeit at diminished hopping distances associated with the greater Earth gravitation. The upper end of each leg is connected through two universal joints to an upper and a lower hexagonal frame, such that the tilt of the leg depends on the relative position of the two frames. Two non-back-driveable worm-gear motor drives are used to control the relative position of the two frames along two axes 120 apart, thereby controlling the common tilt of all six legs and thereby, further, controlling the direction of hopping. Each leg includes an upper and a lower aluminum frame segment with a joint between them. A fiberglass spring, connected via hinges to both segments, is used to store hopping energy prior to launch into a hop and to cushion the landing at the end of the hop. A cable for loading the spring is run into each leg through the center of the universal joints and then down along the center lines of the segments to the lower end of the leg. A central spool actuated by a motor with a harmonic drive and an electromagnetic clutch winds in all six cables to compress all six springs (thereby also flexing all six legs) simultaneously. To ensure that all the legs push off and land in the same direction, timing- belt pulley drives are attached to the leg segments, restricting the flexing and extension of all six legs to a common linear motion. In preparation for a hop, the spool can be driven to load the spring legs by an amount corresponding to a desired hop distance within range. The amount of compression can be computed from the reading of a shaft-angle encoder that

  16. A New Hybrid Gyroscope with Electrostatic Negative Stiffness Tuning

    Directory of Open Access Journals (Sweden)

    Xian Chu

    2013-05-01

    Full Text Available A variety of gyroscopes have been extensively studied due to their capability of precision detection of rotation rates and extensive applications in navigation, guidance and motion control. In this work, a new Hybrid Gyroscope (HG which combines the traditional Dynamically Tuned Gyroscope (DTG with silicon micromachined technology is investigated. The HG not only has the potentiality of achieving the same high precision as the traditional DTG, but also features a small size and low cost. The theoretical mechanism of the HG with a capacitance transducer and an electrostatic torquer is derived and the influence of the installation errors from the capacitance plate and the disc rotor module is investigated. A new tuning mechanism based on negative stiffness rather than the traditional dynamic tuning is proposed. The experimental results prove that the negative stiffness tuning is practicable and a tuning voltage of as high as 63 V is demonstrated. Due to the decreased installation error, the non-linearity of the scale factor is reduced significantly from 11.78% to 0.64%, as well as the asymmetry from 93.3% to 1.56% in the open loop condition. The rebalancing close-loop control is simulated and achieved experimentally, which proves that the fundamental principle of the HG is feasible.

  17. Arterial Stiffness: Pathophysiological and Genetic Aspects

    OpenAIRE

    Alvim, Rafael de Oliveira; Santos, Paulo Caleb Junior Lima; Bortolotto, Luiz Aparecido; Mill, José Geraldo; Pereira, Alexandre da Costa

    2017-01-01

    Abstract Cardiovascular diseases (CVD) are the main cause of mortality and it represents a significant percentage of hospitalizations. In the scenario of minimization of costs of the health system, methods that identify subclinical CVD would be important. Some guidelines include the measures of aortic stiffness and intima-media thickness of the carotid artery as methods to identify subclinical CVD in hypertensive patients. The pulse wave velocity (PWV) is the gold standard for the evaluation ...

  18. On the elastic stiffness of grain boundaries

    International Nuclear Information System (INIS)

    Zhang Tongyi; Hack, J.E.

    1992-01-01

    The elastic softening of grain boundaries is evaluated from the starting point of grain boundary energy. Several examples are given to illustrate the relationship between boundary energy and the extent of softening. In general, a high grain boundary energy is associated with a large excess atomic volume in the boundary region. The consequent reduction in grain boundary stiffness can represent a significant fraction of that observed in bulk crystals. (orig.)

  19. RELAP5 Analyses of OECD/NEA ROSA-2 Project Experiments on Intermediate-Break LOCAs at Hot Leg or Cold Leg

    Science.gov (United States)

    Takeda, Takeshi; Maruyama, Yu; Watanabe, Tadashi; Nakamura, Hideo

    Experiments simulating PWR intermediate-break loss-of-coolant accidents (IBLOCAs) with 17% break at hot leg or cold leg were conducted in OECD/NEA ROSA-2 Project using the Large Scale Test Facility (LSTF). In the hot leg IBLOCA test, core uncovery started simultaneously with liquid level drop in crossover leg downflow-side before loop seal clearing (LSC) induced by steam condensation on accumulator coolant injected into cold leg. Water remained on upper core plate in upper plenum due to counter-current flow limiting (CCFL) because of significant upward steam flow from the core. In the cold leg IBLOCA test, core dryout took place due to rapid liquid level drop in the core before LSC. Liquid was accumulated in upper plenum, steam generator (SG) U-tube upflow-side and SG inlet plenum before the LSC due to CCFL by high velocity vapor flow, causing enhanced decrease in the core liquid level. The RELAP5/MOD3.2.1.2 post-test analyses of the two LSTF experiments were performed employing critical flow model in the code with a discharge coefficient of 1.0. In the hot leg IBLOCA case, cladding surface temperature of simulated fuel rods was underpredicted due to overprediction of core liquid level after the core uncovery. In the cold leg IBLOCA case, the cladding surface temperature was underpredicted too due to later core uncovery than in the experiment. These may suggest that the code has remaining problems in proper prediction of primary coolant distribution.

  20. Effect of Reduced Stiffness Dance Flooring on Lower Extremity Joint Angular Trajectories During a Ballet Jump.

    Science.gov (United States)

    Hackney, James; Brummel, Sara; Newman, Mary; Scott, Shannon; Reinagel, Matthew; Smith, Jennifer

    2015-09-01

    We carried out a study to investigate how low stiffness flooring may help prevent overuse injuries of the lower extremity in dancers. It was hypothesized that performing a ballet jump (sauté) on a reduced stiffness dance floor would decrease maximum joint flexion angles and negative angular velocities at the hips, knees, or ankles compared to performing the same jump on a harder floor. The participants were 15 young adult female dancers (age range 18 to 28, mean = 20.89 ± 2.93 years) with at least 5 years of continuous ballet experience and without history of serious lower body injury, surgery, or recent pain. They performed sautés on a (low stiffness) Harlequin ® WoodSpring Floor and on a vinyl-covered hardwood on concrete floor. Maximum joint flexion angles and negative velocities at bilateral hips, knees, and ankles were measured with the "Ariel Performance Analysis System" (APAS). Paired one-tailed t-tests yielded significant decreases in maximum knee angle (average decrease = 3.4° ± 4.2°, p = 0.026) and angular negative velocity of the ankles (average decrease = 18.7°/sec ± 27.9°/sec, p = 0.009) with low stiffness flooring. If the knee angle is less acute, then the length of the external knee flexion moment arm will also be shorter and result in a smaller external knee flexion moment, given an equal landing force. Also, high velocities of eccentric muscle contraction, which are necessary to control negative angular velocity of the ankle joint, are associated with higher risk of musculotendinous injury. Hence, our findings indicate that reduced floor stiffness may indeed help decrease the likelihood of lower extremity injuries.

  1. Nonlinear Modeling of Cables with Flexural Stiffness

    Directory of Open Access Journals (Sweden)

    Walter Lacarbonara

    2008-01-01

    Full Text Available A geometrically exact formulation of cables suffering axis stretching and flexural curvature is presented. The dynamical formulation is based on nonlinearly viscoelastic constitutive laws for the tension and bending moment with the additional constitutive nonlinearity accounting for the no-compression condition. A continuation method, combined with a mixed finite-difference spatial discretization, is then employed to path-follow the static responses of cables subject to forces or support displacements. These computations, conducted in the quasistatic regime, are based on cables with linearly elastic material behaviors, whereas the nonlinearity is in the geometric stiffness terms and the no-compression behavior. The finite-difference results have been confirmed employing a weak formulation based on quadratic Lagrangian finite elements. The influence of the flexural stiffness on the nonlinear static responses is assessed comparing the results with those obtained for purely extensible cables. The properties of the frequencies of the linear normal modes of cables with flexural stiffness are also investigated and compared with those of purely extensible cables.

  2. Dynamic Stiffness and Damping Characteristics of a High-Temperature Air Foil Journal Bearing

    Science.gov (United States)

    Howard, Samuel A.; DellaCorte, Christopher; Valco, Mark J.; Prahl, Joseph M.; Heshmat, Hooshang

    2001-01-01

    Using a high-temperature optically based displacement measurement system, a foil air bearing's stiffness and damping characteristics were experimentally determined. Results were obtained over a range of modified Sommerfeld Number from 1.5E6 to 1.5E7, and at temperatures from 25 to 538 C. An Experimental procedure was developed comparing the error in two curve fitting functions to reveal different modes of physical behavior throughout the operating domain. The maximum change in dimensionless stiffness was 3.0E-2 to 6.5E-2 over the Sommerfeld Number range tested. Stiffness decreased with temperature by as much as a factor of two from 25 to 538 C. Dimensionless damping was a stronger function of Sommerfeld Number ranging from 20 to 300. The temperature effect on damping being more qualitative, showed the damping mechanism shifted from viscous type damping to frictional type as temperature increased.

  3. A study of function and residual joint stiffness after functional bracing of tibial shaft fractures.

    Science.gov (United States)

    Pun, W K; Chow, S P; Fang, D; Ip, F K; Leong, J C; Ng, C

    1991-06-01

    Ninety-eight diaphyseal tibial fractures were treated with custom made functional braces in 97 patients older than 14 years of age. The average follow-up period was 1.86 years, and 53 patients had more than two years' evaluation (average, 2.83 years). The majority of the patients did not have full range of movement in the ankle and subtalar joints when the brace was removed after fracture healing. Although the stiffness decreased with time, a significant number of patients were left with residual joint stiffness. At an average follow-up period of 1.86 years, 68.4% of the patients had normal ankle motion and 60% had normal inversion and eversion of the hindfoot. In patients with more than two years' evaluation, 75.5% had normal ankle movement and 71.1% had normal inversion and eversion of the foot. In the knee joint, the incidence of residual joint stiffness was small and the amount of stiffness was clinically insignificant. Patients with an abnormal walking pattern after fracture healing had a high incidence of ankle and subtalar joint stiffness.

  4. Mechanomyogram amplitude correlates with human gastrocnemius medialis muscle and tendon stiffness both before and after acute passive stretching.

    Science.gov (United States)

    Longo, Stefano; Cè, Emiliano; Rampichini, Susanna; Devoto, Michela; Limonta, Eloisa; Esposito, Fabio

    2014-10-01

    The study aimed to assess the level of correlation between muscle-tendon unit (MTU) stiffness and mechanomyogram (MMG) signal amplitude of the human gastrocnemius medialis muscle, both before and after acute passive stretching. The passive torque (Tpass), electrically evoked peak torque (pT) and myotendinous junction displacement were determined at different angles of dorsiflexion (0, 10 and 20 deg), while maximum voluntary isometric torque (Tmax) was assessed only at 0 deg. Measurements were repeated after a bout of passive stretching. From the MMG signal, the root mean square (RMS) and peak to peak (p-p) were calculated. The MTU, muscle and tendon stiffness were determined by ultrasound and Tpass measurements. Before stretching, correlations between MMG RMS and MTU, muscle and tendon stiffness were found (R(2) = 0.22-0.46). After stretching, Tpass, Tmax, pT and MTU, muscle and tendon stiffness decreased by 25 ± 7, 16 ± 2, 9 ± 2, 22 ± 7, 23 ± 8 and 28 ± 5%, respectively (P muscle and tendon stiffness were still present after stretching (R(2) = 0.44-0.60). In conclusion, correlations between MMG RMS and stiffness exist both before and after stretching, suggesting that a slacker MTU leads to larger muscle fibre oscillations. However, care must be taken in using MMG amplitude as an indirect index to estimate stiffness owing to the relatively small R(2) values of the investigated correlations. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

  5. Analytical Study of Active Prosthetic Legs

    Science.gov (United States)

    Ono, Kyosuke; Katsumata, Mie

    Walking with prosthesis has not been well analyzed mathematically and it seems that the design of powered prosthesis has been done empirically so far. This paper presents a dynamic simulation of a normal human walking and walking with an active prosthesis. We also studied the two controlling methods of a powered thigh prosthesis based on multi-body simulation of human walking. First we measured the normal human walking gait, then, we showed that a 3-DOF human walking model can walk on level ground by applying tracking control to the measured walking gait within a certain range of tuned walking period. Next, we applied the tracking control and self-excited control to the powered thigh prosthesis and compared the robustness and efficiency of the two control methods by numerical simulation. As a result, we found that the self-excited control can significantly decrease the hip joint torque and specific cost to 1/3 compared with the tracking control. Moreover, the self-excited control is superior to the tracking control because tuning for the walking period is not needed for the active prosthetic leg.

  6. Static stiffness modeling of a novel hybrid redundant robot machine

    Energy Technology Data Exchange (ETDEWEB)

    Li Ming, E-mail: hackingming@gmail.com [Laboratory of Intelligent Machines, Lappeenranta University of Technology (Finland); Wu Huapeng; Handroos, Heikki [Laboratory of Intelligent Machines, Lappeenranta University of Technology (Finland)

    2011-10-15

    This paper presents a modeling method to study the stiffness of a hybrid serial-parallel robot IWR (Intersector Welding Robot) for the assembly of ITER vacuum vessel. The stiffness matrix of the basic element in the robot is evaluated using matrix structural analysis (MSA); the stiffness of the parallel mechanism is investigated by taking account of the deformations of both hydraulic limbs and joints; the stiffness of the whole integrated robot is evaluated by employing the virtual joint method and the principle of virtual work. The obtained stiffness model of the hybrid robot is analytical and the deformation results of the robot workspace under certain external load are presented.

  7. Static stiffness modeling of a novel hybrid redundant robot machine

    International Nuclear Information System (INIS)

    Li Ming; Wu Huapeng; Handroos, Heikki

    2011-01-01

    This paper presents a modeling method to study the stiffness of a hybrid serial-parallel robot IWR (Intersector Welding Robot) for the assembly of ITER vacuum vessel. The stiffness matrix of the basic element in the robot is evaluated using matrix structural analysis (MSA); the stiffness of the parallel mechanism is investigated by taking account of the deformations of both hydraulic limbs and joints; the stiffness of the whole integrated robot is evaluated by employing the virtual joint method and the principle of virtual work. The obtained stiffness model of the hybrid robot is analytical and the deformation results of the robot workspace under certain external load are presented.

  8. Hot Leg Piping Materials Issues

    International Nuclear Information System (INIS)

    V. Munne

    2006-01-01

    With Naval Reactors (NR) approval of the Naval Reactors Prime Contractor Team (NRPCT) recommendation to develop a gas cooled reactor directly coupled to a Brayton power conversion system as the space nuclear power plant (SNPP) for Project Prometheus (References a and b) the reactor outlet piping was recognized to require a design that utilizes internal insulation (Reference c). The initial pipe design suggested ceramic fiber blanket as the insulation material based on requirements associated with service temperature capability within the expected range, very low thermal conductivity, and low density. Nevertheless, it was not considered to be well suited for internal insulation use because its very high surface area and proclivity for holding adsorbed gases, especially water, would make outgassing a source of contaminant gases in the He-Xe working fluid. Additionally, ceramic fiber blanket insulating materials become very friable after relatively short service periods at working temperatures and small pieces of fiber could be dislodged and contaminate the system. Consequently, alternative insulation materials were sought that would have comparable thermal properties and density but superior structural integrity and greatly reduced outgassing. This letter provides technical information regarding insulation and materials issues for the Hot Leg Piping preconceptual design developed for the Project Prometheus space nuclear power plant (SNPP)

  9. Motor hyperactivity of the iron-deficient rat - an animal model of restless legs syndrome.

    Science.gov (United States)

    Lai, Yuan-Yang; Cheng, Yu-Hsuan; Hsieh, Kung-Chiao; Nguyen, Darian; Chew, Keng-Tee; Ramanathan, Lalini; Siegel, Jerome M

    2017-12-01

    Abnormal striatal dopamine transmission has been hypothesized to cause restless legs syndrome. Dopaminergic drugs are commonly used to treat restless legs syndrome. However, they cause adverse effects with long-term use. An animal model would allow the systematic testing of potential therapeutic drugs. A high prevalence of restless legs syndrome has been reported in iron-deficient anemic patients. We hypothesized that the iron-deficient animal would exhibit signs similar to those in restless legs syndrome patients. After baseline polysomnographic recordings, iron-deficient rats received pramipexole injection. Then, iron-deficient rats were fed a standard rodent diet, and polysomnographic recording were performed for 2 days each week for 4 weeks. Iron-deficient rats have low hematocrit levels and show signs of restless legs syndrome: sleep fragmentation and periodic leg movements in wake and in slow-wave sleep. Iron-deficient rats had a positive response to pramipexole treatment. After the iron-deficient rats were fed the standard rodent diet, hematocrit returned to normal levels, and sleep quality improved, with increased average duration of wake and slow-wave sleep episodes. Periodic leg movements decreased during both waking and sleep. Hematocrit levels positively correlated with the average duration of episodes in wake and in slow-wave sleep and negatively correlated with periodic leg movements in wake and in sleep. Western blot analysis showed that striatal dopamine transporter levels were higher in iron-deficient rats. The iron-deficient rat is a useful animal model of iron-deficient anemic restless legs syndrome. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.

  10. Vertical stiffness and muscle strain in professional Australian football.

    Science.gov (United States)

    Serpell, Benjamin G; Scarvell, Jennie M; Ball, Nick B; Smith, Paul N

    2014-12-01

    Abstract The purpose of this study was to establish if vertical stiffness was greater in professional Australian rules footballers who sustained a lower limb skeletal muscle strain compared to those who did not, and to establish if a relationship between age, or training history, and vertical stiffness existed. Thirty-one participants underwent weekly rebound jump testing on a force platform over two seasons. Vertical stiffness was calculated for injured players and the uninjured cohort 1 and 3 weeks prior to sustaining an injury and at the end of preseason. Eighteen athletes were in the "uninjured" cohort and 13 in the "injured" cohort. No significant difference in vertical stiffness was observed between groups (P = 0.18 for absolute stiffness; P = 0.08 for stiffness relative to body mass), within groups (P = 0.83 and P = 0.88, respectively) or for a time*cohort interaction (P = 0.77 and P = 0.80, respectively). No relationship between age and vertical stiffness existed (r = -0.06 for absolute and relative stiffness), or training history and vertical stiffness (r = -0.01 and 0.00 for absolute and relative stiffness, respectively) existed. These results and others lend to suggest that vertical stiffness is not related to lower limb muscle strain injury.

  11. Regional brain stiffness changes across the Alzheimer's disease spectrum

    Directory of Open Access Journals (Sweden)

    Matthew C. Murphy

    2016-01-01

    Full Text Available Magnetic resonance elastography (MRE is an MRI-based technique to noninvasively measure tissue stiffness. Currently well established for clinical use in the liver, MRE is increasingly being investigated to measure brain stiffness as a novel biomarker of a variety of neurological diseases. The purpose of this work was to apply a recently developed MRE pipeline to measure regional brain stiffness changes in human subjects across the Alzheimer's disease (AD spectrum, and to gain insights into the biological processes underlying those stiffness changes by correlating stiffness with existing biomarkers of AD. The results indicate that stiffness changes occur mostly in the frontal, parietal and temporal lobes, in accordance with the known topography of AD pathology. Furthermore, stiffness in those areas correlates with existing imaging biomarkers of AD including hippocampal volumes and amyloid PET. Additional analysis revealed preliminary but significant evidence that the relationship between brain stiffness and AD severity is nonlinear and non-monotonic. Given that similar relationships have been observed in functional MRI experiments, we used task-free fMRI data to test the hypothesis that brain stiffness was sensitive to structural changes associated with altered functional connectivity. The analysis revealed that brain stiffness is significantly and positively correlated with default mode network connectivity. Therefore, brain stiffness as measured by MRE has potential to provide new and essential insights into the temporal dynamics of AD, as well as the relationship between functional and structural plasticity as it relates to AD pathophysiology.

  12. Research on static angular stiffness measurement of flexible joint

    Directory of Open Access Journals (Sweden)

    Yongchao HUANG

    2016-10-01

    Full Text Available Measurement accuracy of the angular stiffness of flexible joint is directly related to the control accuracy and sensitivity of gyro, but the traditional measurement methods have many problems. According to the principle of angular stiffness measurement of flexible joint, two static measurement methods of angular stiffness are proposed based on different loading ways, namely mechanical loading angular stiffness measurement and piezoelectric loading angular stiffness measurement. The mechanical loading angular stiffness measurement system is built by using a motor driven indexing feeding tilting table, the measure experiment if the angular stiffness of flexible joint is conducted, and the angular stiffness of flexible joint is measured. For the excessive fluctuation problem of the measure result in mechanical load test, a piezoelectric loading structure is designed and a measurement method employing piezoelectric actuator is proposed for angular stiffness measurement of flexible joint. Based on ANSYS Workbench, the displacement output of the piezoelectric loading structure is analyzed by simulations. The simulation results illustrate that the displacement output meets the requirement of static loading angular stiffness measurement of flexible joint, and the theoretical feasibility of piezoelectric loading angular stiffness measurement method is validated.

  13. Frustrated spin-1/2 ladder with ferro- and antiferromagnetic legs

    Science.gov (United States)

    Maiti, Debasmita; Dey, Dayasindhu; Kumar, Manoranjan

    2018-01-01

    Two-leg spin-1/2 ladder systems consisting of a ferromagnetic leg and an antiferromagnetic leg are considered where the spins on the legs interact through antiferromagnetic rung couplings J1 . These ladders can have two geometrical arrangements either zigzag or normal ladder and these systems are frustrated irrespective of their geometry. This frustration gives rise to incommensurate spin density wave, dimer and spin fluid phases in the ground state. The magnetization in the systems decreases linearly with J12, and the systems show an incommensurate phase for 0.0

  14. The effect of acute maximal exercise on postexercise hemodynamics and central arterial stiffness in obese and normal-weight individuals.

    Science.gov (United States)

    Bunsawat, Kanokwan; Ranadive, Sushant M; Lane-Cordova, Abbi D; Yan, Huimin; Kappus, Rebecca M; Fernhall, Bo; Baynard, Tracy

    2017-04-01

    Central arterial stiffness is associated with incident hypertension and negative cardiovascular outcomes. Obese individuals have higher central blood pressure (BP) and central arterial stiffness than their normal-weight counterparts, but it is unclear whether obesity also affects hemodynamics and central arterial stiffness after maximal exercise. We evaluated central hemodynamics and arterial stiffness during recovery from acute maximal aerobic exercise in obese and normal-weight individuals. Forty-six normal-weight and twenty-one obese individuals underwent measurements of central BP and central arterial stiffness at rest and 15 and 30 min following acute maximal exercise. Central BP and normalized augmentation index (AIx@75) were derived from radial artery applanation tonometry, and central arterial stiffness was obtained via carotid-femoral pulse wave velocity (cPWV) and corrected for central mean arterial pressure (cPWV/cMAP). Central arterial stiffness increased in obese individuals but decreased in normal-weight individuals following acute maximal exercise, after adjusting for fitness. Obese individuals also exhibited an overall higher central BP ( P  exercise effect. The increase in heart rate was greater in obese versus normal-weight individuals following exercise ( P  exercise effect for AIx@75 In conclusion, obese (but not normal-weight) individuals increased central arterial stiffness following acute maximal exercise. An assessment of arterial stiffness response to acute exercise may serve as a useful detection tool for subclinical vascular dysfunction. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  15. Stiff self-interacting strings at high temperature QCD

    Science.gov (United States)

    S Bakry, A.; Chen, X.; Deliyergiyev, M.; Galal, A.; Khalaf, A.; M Pengming, P.

    2018-03-01

    We investigate the implications of Nambu-Goto (NG), Lüscher Weisz (LW) and Polyakov-Kleinert (PK) effective string actions for the Casimir energy and the width of the quantum delocalization of the string in 4-dim pure SU(3) Yang-Mills lattice gauge theory. At a temperature closer to the critical point T/Tc=0.9, we found that the next to leading-order (NLO) contributions from the expansion of the NG string in addition to the boundary terms in LW action to decrease the deviations from the lattice data in the intermediate distance scales for both the quark-antiquark QQ̅ potential and broadening of the color tube compared to the free string approximation. We conjecture possible stiffness of the QCD string through studying the effects of extrinsic curvature term in PK action and find a good fitting behavior for the lattice Monte-Carlo data at both long and intermediate quark separations regions.

  16. Leg pain (Osgood-Schlatter) (image)

    Science.gov (United States)

    Leg pain in older children or young adolescents can occur for many reasons. An Osgood-Schlatter lesion results from continued trauma to the anterior tibial bone and causes a visible lump below the knee.

  17. Support Leg Loading in Punt Kicking

    Science.gov (United States)

    Kermond, John; Konz, Stephen

    1978-01-01

    Maximum distance in football punt kicking is associated with a maximum force transfer to the ball rather than a maximum force transfer through the ground via the support leg. For maximum distance, tred lightly. (Author)

  18. Sturge-Weber syndrome - legs (image)

    Science.gov (United States)

    ... nervous system (neurocutaneous) and is associated with Port Wine Stain, red vascular markings on the face and other parts of the body (shown here on the legs). This is an unusual case, due to the large size of the lesion ( ...

  19. Leg or foot amputation - dressing change

    Science.gov (United States)

    ... patientinstructions/000018.htm Leg or foot amputation - dressing change To use the sharing features on this page, please enable JavaScript. You will need to change the dressing on your limb. This will help ...

  20. Restless legs syndrome in migraine patients: prevalence and severity.

    Science.gov (United States)

    van Oosterhout, W P J; van Someren, E J W; Louter, M A; Schoonman, G G; Lammers, G J; Rijsman, R M; Ferrari, M D; Terwindt, G M

    2016-06-01

    Our aim was to study not only the prevalence but more importantly the severity and the correlation between sleep quality and restless legs syndrome (RLS) in a large population of well-defined migraine patients as poor sleep presumably triggers migraine attacks. In a large cross-sectional and observational study, data on migraine and RLS were collected from 2385 migraine patients (according to the International Classification of Headache Disorders ICHD-IIIb) and 332 non-headache controls. RLS severity (International RLS Study Group severity scale) and sleep quality (Pittsburgh Sleep Quality Index) were assessed. Risk factors for RLS and RLS severity were calculated using multivariable-adjusted regression models. Restless legs syndrome prevalence in migraine was higher than in controls (16.9% vs. 8.7%; multivariable-adjusted odds ratio 1.83; 95% confidence interval 1.18-2.86; P = 0.008) and more severe (adjusted severity score 14.5 ± 0.5 vs. 12.0 ± 1.1; P = 0.036). Poor sleepers were overrepresented amongst migraineurs (50.1% vs. 25.6%; P Restless legs syndrome is not only twice as prevalent but also more severe in migraine patients, and associated with decreased sleep quality. © 2016 EAN.

  1. Leg ulcer in Werner syndrome (adult progeria): a case report.

    Science.gov (United States)

    Fumo, Giuseppe; Pau, Monica; Patta, Federico; Aste, Nicola; Atzori, Laura

    2013-03-15

    Werner syndrome (WS; MIM#277700) or adult progeria, is a rare disease, associated with mutations of a single gene (RECQL2 or WRN), located on chromosome 8 (8p12). It codes a DNA-helicase, whose defects cause genomic instability. The highest incidences are reported in Japan and Sardinia (Italy). On this major island of the Mediterranean Basin, the WS cases have been observed in the northern areas. The authors describe the apparently first case reported in southern Sardinia, a 51-year-old woman, who was born in and resides in the province of Cagliari. She presented with a 9-year history of an intractable leg ulcer and other characteristic symptoms, including "bird-like" face, high-pitched voice, premature greying, short stature, abdominal obesity in contrast with thin body type, scleroderma-like legs, decreased muscle mass, diabetes, atherosclerosis, and premature menopause. A specialized genetic Institute of Research (IRCCS-IDI, Rome) confirmed the clinical diagnosis. There is no cure or specific treatment and patients must be periodically screened for an increased risk of cardiovascular and cerebrovascular disease and malignancies. Among the many findings, leg ulcers significantly affect the patient's quality of life. This problem may send the patient to the dermatologist, who finally suspects the diagnosis. Poor response to medical treatment may require aggressive repeated surgery, with poor or temporary results.

  2. Ultrasonography of the lower leg: technique, anatomy and pathologic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Thain, L.M.F. [Univ. of Western Ontario, London Health Sciences Centre, Departments of Diagnostic Radiology and Nuclear Medicine, London, Ontario (Canada); Lee, S.L. [Univ. of Western Ontario, Dept. of Anaestesia, London, Ontario (Canada); Downey, D.B. [Univ. of Western Ontario, Diagnostic Ultrasound, London Health Sciences Centre, Dept. of Diagnostic Radiology and Nuclear Medicine, London, Ontario (Canada)

    2001-10-01

    Ultrasonography (US) is a useful modality for examining the lower leg, particularly in patients who have sustained muscular, tendinous or bony injuries. This paper will demonstrate the proper technique for US examination of each compartment of the lower leg. The bones, muscles and tendons of the lower leg (i.e., patellar tendon, superficial posterior fascial compartment [gastrocnemius, plantaris, soleus], deep posterior fascial compartment [tibialis posterior, flexor digitorum longus, flexor hallucis longus], lateral fascial compartment [peroneus longus, peroneus brevis], anterior faccial compartment [tibialis anterior, extensor digitorum longus, extensor hallucis longus], tibia and the fibula) will be reviewed with respect to their surface anatomy, US appearance and common pathologic conditions. A linear array high-frequency (at least 7.5 MHz) transducer should be used. One with variable centre frequency is useful to allow the examination of both deep and superficial areas in the same patient without switching transducers. Power Doppler is used to identify areas of increased blood flow, often due to inflammation or active healing. The transducer must be maintained perpendicular to the long axis of tendons to avoid anisotropy artifacts, which give a false appearance of decreased echogenicity. Structures should be followed from origin to insertion in the long and short axes. (author)

  3. Ultrasonography of the lower leg: technique, anatomy and pathologic conditions

    International Nuclear Information System (INIS)

    Thain, L.M.F.; Lee, S.L.; Downey, D.B.

    2001-01-01

    Ultrasonography (US) is a useful modality for examining the lower leg, particularly in patients who have sustained muscular, tendinous or bony injuries. This paper will demonstrate the proper technique for US examination of each compartment of the lower leg. The bones, muscles and tendons of the lower leg (i.e., patellar tendon, superficial posterior fascial compartment [gastrocnemius, plantaris, soleus], deep posterior fascial compartment [tibialis posterior, flexor digitorum longus, flexor hallucis longus], lateral fascial compartment [peroneus longus, peroneus brevis], anterior faccial compartment [tibialis anterior, extensor digitorum longus, extensor hallucis longus], tibia and the fibula) will be reviewed with respect to their surface anatomy, US appearance and common pathologic conditions. A linear array high-frequency (at least 7.5 MHz) transducer should be used. One with variable centre frequency is useful to allow the examination of both deep and superficial areas in the same patient without switching transducers. Power Doppler is used to identify areas of increased blood flow, often due to inflammation or active healing. The transducer must be maintained perpendicular to the long axis of tendons to avoid anisotropy artifacts, which give a false appearance of decreased echogenicity. Structures should be followed from origin to insertion in the long and short axes. (author)

  4. Is There an Association between Restless Legs Syndrome and Urticaria?

    Science.gov (United States)

    Tuna, Serpil; Alan, Sevil; Samancı, Nehir; Karakaş, Ayşe Akman

    2016-05-01

    Restless legs syndrome (RLS) is a disease characterized by the urge to move the legs and sleep disturbances. Similarly, chronic spontaneous urticaria (CSU) is a dermatological disease characterized by pruritus and sleep disorders. In this study, we aimed to determine the prevalence and severity of RLS in patients with chronic spontaneous urticaria (CSU) and to compare the quality of sleep of patients with and without RLS in the CSU group using the Pittsburgh Sleep Quality Index. A total of 130 patients with CSU and 100 healthy controls were included in this study. The frequency of RLS, frequency of sleep disturbances, and average score of RLS in patients with CSU were statistically significantly higher than control groups (respectively P = 0.008, P = 0.009, P = 0.004). Subjective sleep quality, sleep latency and habitual sleep efficiency scores in patients with RLS were statistically significantly higher than patients without RLS (respectively P = 0.016, P = 0.007, P = 0.035). We claimed that pruritus of urticaria may decrease the quality of sleep in patients with RLS and it may trigger and worsen the restless legs syndrome. Furthermore, RLS and CSU may share a common etiology.

  5. Organic trace minerals and 25-hydroxycholecalciferol affect performance characteristics, leg abnormalities, and biomechanical properties of leg bones of turkeys.

    Science.gov (United States)

    Ferket, P R; Oviedo-Rondón, E O; Mente, P L; Bohórquez, D V; Santos, A A; Grimes, J L; Richards, J D; Dibner, J J; Felts, V

    2009-01-01

    Leg problems and resulting mortality can exceed 1% per week in turkey toms starting at approximately 15 wk of age. Dietary supplementation of organic trace minerals (MIN) and 25-hydroxycholecalciferol (HyD) may improve performance, decrease incidence of leg abnormalities, and increase bone strength. Nicholas 85X700 toms were assigned to 4 treatments consisting of a factorial arrangement of 2 concentrations of MIN (0 and 0.1% of Mintrex P(Se), which adds 40, 40, 20, and 0.3 mg/kg of Zn, Mn, Cu, and Se, respectively) and 2 concentrations of HyD (0 and 92 microg/kg of HyD). Diets were formulated to be equal in nutrient content and fed ad libitum as 8 feed phases. Feed intake and BW were measured at 6, 12, 15, 17, and 20 wk of age. Valgus, varus, and shaky leg defects were determined at 12, 15, 17, and 20 wk of age. Tibia and femur biomechanical properties were evaluated by torsion and bending tests at 17 wk of age. There were no treatment effects on BW. Only MIN significantly improved feed conversion ratio through to 20 wk of age. Cumulative mortality at 3 wk of age was greater among the MIN birds, but it was lower by 20 wk (P = 0.085). The MIN decreased the incidence of varus defects at 17 wk of age; shaky leg at 12, 15, and 17 wk of age; and valgus defects at 15, 17, and 20 wk of age. There were no MIN x HyD interaction effects on individual gait problems. Maximum load and the bending stress required for tibias to break in a 4-point assay were increased with MIN supplementation, especially when HyD was also added. Maximum shear stress at failure of femoral bones in a torsion assay was increased by supplementation with both MIN and HyD together. Dietary supplementation of MIN and HyD may improve biomechanical properties of bones. Dietary MIN supplementation may improve feed conversion of turkeys, likely by decreasing leg problems.

  6. Conjoined legs: Sirenomelia or caudal regression syndrome?

    OpenAIRE

    Das, Sakti Prasad; Ojha, Niranjan; Ganesh, G Shankar; Mohanty, Ram Narayan

    2013-01-01

    Presence of single umbilical persistent vitelline artery distinguishes sirenomelia from caudal regression syndrome. We report a case of a12-year-old boy who had bilateral umbilical arteries presented with fusion of both legs in the lower one third of leg. Both feet were rudimentary. The right foot had a valgus rocker-bottom deformity. All toes were present but rudimentary. The left foot showed absence of all toes. Physical examination showed left tibia vara. The chest evaluation in sitting re...

  7. Efficiency and Speed in Legged Robots

    Science.gov (United States)

    2011-03-22

    which we substitute into (4.42) : ( -mv s J O=-km+ mvc -k __ c __ V v 2 c c 46 (4.43) (4.44) (4.45) (4.46) to fInd the switching curve m 3 s...Legged Mechanisms. IVSS. Traverse City, MI Muench, P., Alexander, J., Quinn, R., & Aschenbeck, K. (2005) Pneumatic Spring for Legged Walker. SPIE

  8. Flexural characteristics of a stack leg

    International Nuclear Information System (INIS)

    Cook, J.

    1979-06-01

    A 30 MV tandem Van de Graaff accelerator is at present under construction at Daresbury Laboratory. The insulating stack of the machine is of modular construction, each module being 860 mm in length. Each live section stack module contains 8 insulating legs mounted between bulkhead rings. The design, fabrication (from glass discs bonded to stainless steel discs using an epoxy film adhesive) and testing of the stack legs is described. (U.K.)

  9. Three cross leg flaps for lower leg reconstruction of Gustilo type III C open fracture

    Directory of Open Access Journals (Sweden)

    Kazufumi Sano

    2016-01-01

    Full Text Available A 60 year old male had Gustilo type III C open fracture of the right lower leg. After radical debridement, the large open defect including certain loss of the bone tissue was successfully augmented and covered, by consecutive three cross-leg flaps, which consisted of the free rectus abdominis musculocutaneous flap, the fibula osteocutaneous flap and the conventional sural flap. Although indication for amputation or preservation is decided with multiple factors in each case, a strategic combination of cross-leg flap, free flap, external fixation and vascular delay could increase the potential of preservation of the lower leg with even disastrous Gustilo type III C.

  10. Thompson′s quadricepsplasty for stiff knee

    Directory of Open Access Journals (Sweden)

    Kundu Z

    2007-01-01

    Full Text Available Background : Stiffness of the knee after trauma and/or surgery for femoral fractures is one of the most common complications and is difficult to treat. Stiffness in extension is more common and can be reduced by vigorous physiotherapy. If it does not improve then quadricepsplasty is indicated. The present study was undertaken to evaluate the results of Thompsons quadricepsplasty. Materials and Methods : 22 male patients (age range 20-45 years with posttraumatic knee stiffness following distal femoral fractures underwent Thompson′s quadricepsplasty where knee flexion range was less than 45°. The index injury in these patients was treated with plaster cast (n=5, plates (n=3, intramedullary nailing (n=3 and external fixator for open fractures (n=9. Thompson′s quadricepsplasty was performed in all the patients using anterior approach, with incision extending from upper thigh to tibial tubercle. Release of rectus femoris from underlying vastus intermedius and release of intraarticular adhesions were performed. After surgery the patients needed parentral analgesia for three days and then oral analgesics for three weeks. Active assisted knee mobilization exercises were started on the first post-operative day. Continous passive motion machine was used from the same day. Supervised physiotherapy was continued in hospital for six weeks followed by intensive knee flexion and extension exercise including cycling at home for atleast another six months. Results : Out of 22 patients, 20 had excellent to good results and two patients had poor results using criteria devised by Judet. One poor result was due to peroperative fracture of patella which was then internally fixed and hence the flexion of knee could not be started immediately. There was peroperative avulsion of tibial tuberosity in another patient who finally gained less than 50° knee flexion and hence a poor result. Conclusion : Thompsons quadricepsplasty followed by a strict and rigourous

  11. Arterial stiffness assessment in patients with phenylketonuria

    Science.gov (United States)

    Hermida-Ameijeiras, Alvaro; Crujeiras, Vanesa; Roca, Iria; Calvo, Carlos; Leis, Rosaura; Couce, María-Luz

    2017-01-01

    Abstract In patients with phenylketonuria (PKU) compliant to diet greater tendency to overweight and higher inflammatory biomarkers levels than controls were reported. Although this could lead to atherogenesis, the elastic properties of large arteries in PKU patients have never been assessed. The aim of this study was to assess arterial stiffness measured by applanation tonometry in PKU patients compared to healthy controls. We carried out a cross-sectional study in 41 PKU patients (range age: 6–50 years old) and 41 age- and gender-matched healthy controls. Evaluated data included pharmacological treatment with sapropterin, clinical, and biochemical parameters. Aortic stiffness was assessed noninvasively by applanation tonometry measuring central blood pressure, aortic augmentation index (Aix@HR75), augmentation pressure (AP), and pulse wave velocity (PWV). We found higher PWV in classic PKU patients (6.60 m/second vs 5.26 m/second; P: .044). Percentage of PKU patients with PWV above 90 percentile was higher than controls (14.63% vs 2.32%; P: .048). A positive relationship was observed between the annual Phe median and PWV (r: 0.496; P: .012). PKU subjects with lower Phe tolerance showed more body weight (67.6 kg vs 56.8 kg; P: .012) and more PWV than those with higher Phe tolerance (6.55 m/second vs 5.42 m/second; P: .044). Our data show increased aortic stiffness in PKU patients, measured by applanation tonometry, when compared to healthy controls. Higher Phe levels are associated with a bigger PWV increase, which is not present in those subjects compliant to diet or under sapropterin treatment. These results could have marked effects in both research and clinical daily practice for a proper evaluation of cardiovascular risk in PKU subjects. PMID:29390507

  12. The link between exercise and titin passive stiffness.

    Science.gov (United States)

    Lalande, Sophie; Mueller, Patrick J; Chung, Charles S

    2017-09-01

    What is the topic of this review? This review focuses on how in vivo and molecular measurements of cardiac passive stiffness can predict exercise tolerance and how exercise training can reduce cardiac passive stiffness. What advances does it highlight? This review highlights advances in understanding the relationship between molecular (titin-based) and in vivo (left ventricular) passive stiffness, how passive stiffness modifies exercise tolerance, and how exercise training may be therapeutic for cardiac diseases with increased passive stiffness. Exercise can help alleviate the negative effects of cardiovascular disease and cardiovascular co-morbidities associated with sedentary behaviour; this may be especially true in diseases that are associated with increased left ventricular passive stiffness. In this review, we discuss the inverse relationship between exercise tolerance and cardiac passive stiffness. Passive stiffness is the physical property of cardiac muscle to produce a resistive force when stretched, which, in vivo, is measured using the left ventricular end diastolic pressure-volume relationship or is estimated using echocardiography. The giant elastic protein titin is the major contributor to passive stiffness at physiological muscle (sarcomere) lengths. Passive stiffness can be modified by altering titin isoform size or by post-translational modifications. In both human and animal models, increased left ventricular passive stiffness is associated with reduced exercise tolerance due to impaired diastolic filling, suggesting that increased passive stiffness predicts reduced exercise tolerance. At the same time, exercise training itself may induce both short- and long-term changes in titin-based passive stiffness, suggesting that exercise may be a treatment for diseases associated with increased passive stiffness. Direct modification of passive stiffness to improve exercise tolerance is a potential therapeutic approach. Titin passive stiffness itself may

  13. Flexible Sensors for Pressure Therapy: Effect of Substrate Curvature and Stiffness on Sensor Performance.

    Science.gov (United States)

    Khodasevych, Iryna; Parmar, Suresh; Troynikov, Olga

    2017-10-20

    Flexible pressure sensors are increasingly being used in medical and non-medical applications, and particularly in innovative health monitoring. Their efficacy in medical applications such as compression therapy depends on the accuracy and repeatability of their output, which in turn depend on factors such as sensor type, shape, pressure range, and conformability of the sensor to the body surface. Numerous researchers have examined the effects of sensor type and shape, but little information is available on the effect of human body parameters such as support surfaces' curvature and the stiffness of soft tissues on pressure sensing performance. We investigated the effects of body parameters on the performance of pressure sensors using a custom-made human-leg-like test setup. Pressure sensing parameters such as accuracy, drift and repeatability were determined in both static (eight hours continuous pressure) and dynamic (10 cycles of pressure application of 30 s duration) testing conditions. The testing was performed with a focus on compression therapy application for venous leg ulcer treatments, and was conducted in a low-pressure range of 20-70 mmHg. Commercially available sensors manufactured by Peratech and Sensitronics were used under various loading conditions to determine the influence of stiffness and curvature. Flat rigid, flat soft silicone and three cylindrical silicone surfaces of radii of curvature of 3.5 cm, 5.5 cm and 6.5 cm were used as substrates under the sensors. The Peratech sensor averaged 94% accuracy for both static and dynamic measurements on all substrates; the Sensitronics sensor averaged 88% accuracy. The Peratech sensor displayed moderate variations and the Sensitronics sensor large variations in output pressure readings depending on the underlying test surface, both of which were reduced markedly by individual pressure calibration for surface type. Sensor choice and need for calibration to surface type are important considerations for

  14. Vibration Control via Stiffness Switching of Magnetostrictive Transducers

    Science.gov (United States)

    Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.

    2016-01-01

    This paper presents a computational study of structural vibration control that is realized by switching a magnetostrictive transducer between high and low stiffness states. Switching is accomplished by either changing the applied magnetic field with a voltage excitation or changing the shunt impedance on the transducer's coil (i.e., the magnetostrictive material's magnetic boundary condition). Switched-stiffness vibration control is simulated using a lumped mass supported by a damper and the magnetostrictive transducer (mount), which is represented by a nonlinear, electromechanical model. Free vibration of the mass is calculated while varying the mount's stiffness according to a reference switched-stiffness vibration control law. The results reveal that switching the magnetic field produces the desired change in stiffness, but also an undesired actuation force that can significantly degrade the vibration control. Hence, a modified switched-stiffness control law that accounts for the actuation force is proposed and implemented for voltage-controlled stiffness switching. The influence of the magnetomechanical bias condition is also discussed. Voltage-controlled stiffness switching is found to introduce damping equivalent to a viscous damping factor up to about 0.25; this is shown to primarily result from active vibration reduction caused by the actuation force. The merit of magnetostrictive switched-stiffness vibration control is then quantified by comparing the results of voltage- and shunt-controlled stiffness switching to the performance of optimal magnetostrictive shunt damping.

  15. Gain changes in sensorimotor pathways of the locust leg

    Science.gov (United States)

    BÜSchges; Wolf

    1996-01-01

    Feedback systems that control the leg joints of animals must be highly flexible in adapting to different behavioural tasks. One manifestation of such flexibility is changes in the gain of joint control networks. The femur­tibia (FT) control network of the locust leg is one of the feedback systems most thoroughly studied with regard to its neural circuitry. Despite excellent information concerning network topology, however, actual gain changes and their underlying mechanisms have not yet been examined because of the marked spontaneous variations in the action of the control network for this joint. We describe a behavioural situation and a preparation in which the locust (Locusta migratoria L.) FT control network exhibits reproducible changes in gain, allowing investigation of the neuronal basis of gain control. After ('fictive') flight motor activity, the gain of resistance reflexes in the FT joint of the locust middle leg is significantly decreased, with the flexor tibiae muscles being affected more strongly than the extensor muscles. Immediately after flight motor activity, the gain may be as low as 30 % of pre-flight levels. It returns to pre-flight values in under 150 s. The decrease in gain following flight motor activity is due to a decrease in motoneurone recruitment in the resistance reflex elicited by stimulation of the appropriate mechanoreceptor, the femoral chordotonal organ. Motoneurone recruitment is changed as a result of a drastic decline in the stimulus-related synaptic input to the motoneurones, which appears to be produced exclusively at the level of the pre-motor network. Two factors led to this conclusion: first, we found no indication of changes in membrane potential or membrane conductance of the tibia flexor and extensor motoneurones; second, recording from identified pre-motor nonspiking interneurones demonstrated that these may be involved in the observed gain changes. The putative behavioural relevance is discussed.

  16. Deletion of Drosophila muscle LIM protein decreases flight muscle stiffness and power generation

    OpenAIRE

    Clark, Kathleen A.; Lesage-Horton, Heather; Zhao, Cuiping; Beckerle, Mary C.; Swank, Douglas M.

    2011-01-01

    Muscle LIM protein (MLP) can be found at the Z-disk of sarcomeres where it is hypothesized to be involved in sensing muscle stretch. Loss of murine MLP results in dilated cardiomyopathy, and mutations in human MLP lead to cardiac hypertrophy, indicating a critical role for MLP in maintaining normal cardiac function. Loss of MLP in Drosophila (mlp84B) also leads to muscle dysfunction, providing a model system to examine MLP's mechanism of action. Mlp84B-null flies that survive to adulthood are...

  17. Primary stability and stiffness in ankle arthrodes-crossed screws versus anterior plating.

    Science.gov (United States)

    Betz, Michael M; Benninger, Emanuel E; Favre, Philipp P; Wieser, Karl K; Vich, Magdalena M; Espinosa, Norman

    2013-09-01

    Ankle arthrodesis is commonly used for the treatment of osteoarthritis or failed arthroplasty. Screw fixation is the predominant technique to perform ankle arthrodesis. Due to a considerable frequency of failures research suggests the use of an anatomically shaped anterior double plate system as a reliable method for isolated tibiotalar arthrodesis. The purpose of the present biomechanical study was to compare two groups of ankle fusion constructs - three screw fixation and an anterior double plate system - in terms of primary stability and stiffness. Six matched-pairs human cadaveric lower legs (Thiel fixated) were used in this study. One specimen from each pair was randomly assigned to be stabilized with the anterior double plate system and the other with the three-screw technique. The different arthrodesis methods were tested by dorsiflexing the foot until failure of the system, defined as rotation of the talus relative to the tibia in the sagittal plane. Experiments were performed on a universal materials testing machine. The force required to make arthrodesis fail was documented. For calculation of the stiffness, a linear regression was fitted to the force-displacement curve in the linear portion of the curve and its slope taken as the stiffness. For the anatomically shaped double-plate system a mean load of 967N was needed (range from 570N to 1400N) to make arthrodesis fail. The three-screw fixation method resisted a mean load of 190N (range from 100N to 280N) (p=0.005). In terms of stiffness a mean of 56N/mm (range from 35N/mm to 79N/mm) was achieved for the anatomically shaped double-plate system whereas a mean of 10N/mm (range from 6N/mm to 18N/mm) was achieved for the three-screw fixation method (p=0.004). Our biomechanical data demonstrates that the anterior double-plate system is significantly superior to the three-screw fixation technique for ankle arthrodesis in terms of primary stability and stiffness. Copyright © 2013 European Foot and Ankle

  18. Pipe elbow stiffness coefficients including shear and bend flexibility factors for use in direct stiffness codes

    International Nuclear Information System (INIS)

    Perry, R.F.

    1977-01-01

    Historically, developments of computer codes used for piping analysis were based upon the flexibility method of structural analysis. Because of the specialized techniques employed in this method, the codes handled systems composed of only piping elements. Over the past ten years, the direct stiffness method has gained great popularity because of its systematic solution procedure regardless of the type of structural elements composing the system. A great advantage is realized with a direct stiffness code that combines piping elements along with other structural elements such as beams, plates, and shells, in a single model. One common problem, however, has been the lack of an accurate pipe elbow element that would adequately represent the effects of transverse shear and bend flexibility factors. The purpose of the present paper is to present a systematic derivation of the required 12x12 stiffness matrix and load vectors for a three dimensional pipe elbow element which includes the effects of transverse shear and pipe bend flexibility according to the ASME Boiler and Pressure Vessel Code, Section III. The results are presented analytically and as FORTRAN subroutines to be directly incorporated into existing direct stiffness codes. (Auth.)

  19. Elastic metamaterial beam with remotely tunable stiffness

    Science.gov (United States)

    Qian, Wei; Yu, Zhengyue; Wang, Xiaole; Lai, Yun; Yellen, Benjamin B.

    2016-02-01

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ˜30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves.

  20. Elastic metamaterial beam with remotely tunable stiffness

    International Nuclear Information System (INIS)

    Qian, Wei; Yu, Zhengyue; Wang, Xiaole; Lai, Yun; Yellen, Benjamin B.

    2016-01-01

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ∼30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves

  1. The pendulum test as a tool to evaluate passive knee stiffness and viscosity of patients with rheumatoid arthritis

    Directory of Open Access Journals (Sweden)

    Vinci Maria

    2006-11-01

    Full Text Available Abstract Background The pendulum test of Wartenberg is a technique commonly used to measure passive knee motion with the aim to assess spasticity. We used this test to evaluate changes of the knee angular displacement, passive stiffness and viscosity in rheumatoid arthritis patients. Stiffness and viscosity represent passive resistances to joint motion associated with the structural properties of the joint tissue and of the muscular-tendon complex. Stiffness can be considered an intrinsic property of the tissues to resist deformation, while viscosity is related to cohesive forces between adjacent layers of tissues. Both parameters may influence the joint range of motion affecting angular displacement. Methods Nine women with rheumatoid arthritis were compared with a group of healthy women. With the subject half-lying, the relaxed knee was dropped from near-full extension and the characteristics of the ensuring damped unsustained knee oscillation evaluated. The kinematics of leg oscillations was recorded using ultrasonic markers (Zebris CMS HS 10 and the kinetic data were calculated from kinematic and anthropometric measures. Results Knee stiffness significantly increased (p 2 = 0.68 and first flexion (R2 = 0.78. Using a multivariate regression, we found that increasing stiffness was the main factor for the reduction of flexion and extension motions. Conclusion We showed that the Wartenberg test can be considered a practical tool to measure mechanical changes of knee caused by rheumatoid arthritis. This novel application of Wartenberg test could be useful to follow up the effects of pharmacological and rehabilitative interventions in this disease.

  2. Genetic parameters for claw and leg health, foot and leg conformation, and locomotion in Danish Holsteins

    DEFF Research Database (Denmark)

    Laursen, M. V.; Boelling, D.; Mark, Thomas

    2009-01-01

    The purpose of this study was to estimate the genetic correlations among claw and leg health and potential indicator traits. Claw health was defined as absence of heel horn erosion, interdigital dermatitis, interdigital phlegmon, interdigital hyperplasia, laminitis, and sole ulcer. Leg health...

  3. Arterial stiffness, hypertension, and rational use of nebivolol

    Directory of Open Access Journals (Sweden)

    Enrico Agabiti-Rosei

    2009-05-01

    Full Text Available Enrico Agabiti-Rosei, Enzo Porteri, Damiano RizzoniClinica Medica, Department of Medical and Surgical Sciences, University of Brescia, ItalyAbstract: Arterial stiffness plays a key role in the pathophysiology of the cardiovascular system. Some indices of arterial stiffness (pulse wave velocity, augmentation index, characteristics of central blood pressure waveform may be presently calculated and evaluated in the clinical setting. Age and blood pressure are the two major clinical determinants of increased arterial stiffness, while molecular determinants of arterial stiffness are related to fibrotic components of the extracellular matrix, mainly elastin, collagen and fibronectin. Increased arterial stiffness has been consistently observed in conditions such as hypertension, dyslipidemia and diabetes. Arterial stiffness evaluated by means of carotid-femoral pulse wave velocity yielded prognostic significance beyond and above traditional risk factors. A more favorable effect of calcium channel blockers, diuretics and ACE inhibitors compared with β-blockers on indices of arterial stiffness was observed in several studies. It is conceivable that newer β-blockers with additional vasodilating properties, such as nebivolol, which has favorable effects on carbohydrate and lipid metabolism, as well as on endothelial function and on oxidative stress, may have favorable effects on arterial stiffness, compared with atenolol. In fact, in recent studies, nebivolol was demonstrated to improve artery stiffness to a greater extent than older β-blockers. Because endothelial dysfunction and increased arterial stiffness play an important role in the early atherosclerotic processes and are associated with poor outcomes and increased mortality, independently of blood pressure, the ability of nebivolol to enhance release of endothelium-derived nitric oxide, and consequently improve endothelial function and arterial stiffness, may have significant clinical

  4. Stiffness Analysis and Improvement of Bolt-Plate Contact Assemblies

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard; Pedersen, Pauli

    2008-01-01

    and the plate is extended by the possibility of designing a gap, that is, a nonuniform distance between the bolt and plate before prestressing. Designing the gap function generates the possibility for a better stress field by which the stiffness of the bolt is lowered, and at the same time the stiffness...... of the members is increased. Both of these changes have a positive influence on the lifetime of the connections. From designing a varying gap size distribution, it is found that the stiffness become a function of the loading. It is shown that similar improvements in the stiffness ratio between the bolt...

  5. Stiffness and the automatic selection of ODE codes

    International Nuclear Information System (INIS)

    Shampine, L.F.

    1984-01-01

    The author describes the basic ideas behind the most popular methods for the numerical solution of ordinary differential equations (ODEs). He takes up the qualitative behavior of solutions of ODEs and its relation ot the propagation of numerical error. Codes for ODEs are intended either for stiff problems or for non-stiff problems. The difference is explained. Users of codes do not have the information needed to recognize stiffness. A code, DEASY, which automatically recognizes stiffness and selects a suitable method is described

  6. One-legged endurance training: leg blood flow and oxygen extraction during cycling exercise

    DEFF Research Database (Denmark)

    Rud, B; Foss, O; Krustrup, Peter

    2012-01-01

    Aim: As a consequence of enhanced local vascular conductance, perfusion of muscles increases with exercise intensity to suffice the oxygen demand. However, when maximal oxygen uptake (VO(2) max) and cardiac output are approached, the increase in conductance is blunted. Endurance training increases...... muscle metabolic capacity, but to what extent that affects the regulation of muscle vascular conductance during exercise is unknown. Methods: Seven weeks of one-legged endurance training was carried out by twelve subjects. Pulmonary VO(2) during cycling and one-legged cycling was tested before and after...... training, while VO(2) of the trained leg (TL) and control leg (CL) during cycling was determined after training. Results: VO(2) max for cycling was unaffected by training, although one-legged VO(2) max became 6.7 (2.3)% (mean ± SE) larger with TL than with CL. Also TL citrate synthase activity was higher...

  7. High strength steels, stiffness of vehicle front-end structure, and risk of injury to rear seat occupants.

    Science.gov (United States)

    Sahraei, Elham; Digges, Kennerly; Marzougui, Dhafer; Roddis, Kim

    2014-05-01

    Previous research has shown that rear seat occupant protection has decreased over model years, and front-end stiffness is a possible factor causing this trend. In this research, the effects of a change in stiffness on protection of rear seat occupants in frontal crashes were investigated. The stiffness was adjusted by using higher strength steels (DP and TRIP), or thicker metal sheets. Finite element simulations were performed, using an LS Dyna vehicle model coupled with a MADYMO dummy. Simulation results showed that an increase in stiffness, to the extent it happened in recent model years, can increase the risk of AIS3+ head injuries from 4.8% in the original model (with a stiffness of 1,000 N/mm) to 24.2% in a modified model (with a stiffness of 2,356 N/mm). The simulations also showed an increased risk of chest injury from 9.1% in the original model to 11.8% in the modified model. Distribution of injuries from real world accident data confirms the findings of the simulations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Chorein Sensitivity of Actin Polymerization, Cell Shape and Mechanical Stiffness of Vascular Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Ioana Alesutan

    2013-09-01

    Full Text Available Background/Aims: Endothelial cell stiffness plays a key role in endothelium-dependent control of vascular tone and arterial blood pressure. Actin polymerization and distribution of microfilaments is essential for mechanical cell stiffness. Chorein, a protein encoded by the VPS13A gene, defective in chorea-acanthocytosis (ChAc, is involved in neuronal cell survival as well as cortical actin polymerization of erythrocytes and blood platelets. Chorein is expressed in a wide variety of further cells, yet nothing is known about the impact of chorein on cells other than neurons, erythrocytes and platelets. The present study explored whether chorein is expressed in human umbilical vein endothelial cells (HUVECs and addressed the putative role of chorein in the regulation of cytoskeletal architecture, stiffness and survival of those cells. Methods: In HUVECs with or without silencing of the VPS13A gene, VPS13A mRNA expression was determined utilizing quantitative RT-PCR, cytoskeletal organization visualized by confocal microscopy, G/F actin ratio and phosphorylation status of focal adhesion kinase quantified by western blotting, cell death determined by flow cytometry, mechanical properties studied by atomic force microscopy (AFM and cell morphology analysed by scanning ion conductance microscopy (SICM. Results: VPS13A mRNA expression was detectable in HUVECs. Silencing of the VPS13A gene attenuated the filamentous actin network, decreased the ratio of soluble G-actin over filamentous F-actin, reduced cell stiffness and changed cell morphology as compared to HUVECs silenced with negative control siRNA. These effects were paralleled by a significant decrease in FAK phosphorylation following VPS13A silencing. Moreover, silencing of the VPS13A gene increased caspase 3 activity and induced necrosis in HUVECs. Conclusions: Chorein is a novel regulator of cytoskeletal architecture, cell shape, mechanical stiffness and survival of vascular endothelial cells.

  9. Analysis of the body mass index and leg profiles of Asian women after total leg sculpture.

    Science.gov (United States)

    Tsai, Feng-Chou; Chen, Chien-Hao; Lin, Chan-Yi; Ho, Li-Yung

    2009-08-01

    In addition to the conventional methods used to improve leg contours, total leg sculpture, including liposuction, selective neurectomy, and transilluminated powered phlebectomy, provides a one-time solution of leg contour problems, which is a major aesthetic concern among Asian women. The authors present the postoperative results of total leg sculpture and determine any significance and correlation between the leg variables and body mass index by statistical analysis. Thirty female patients who underwent total leg sculpture between 2005 and 2008 were included in the study, and prospective analysis of the patients' data was performed during a follow-up period of 1 year. Local measurement variables and body mass index were recorded, and the correlation between them was determined by Pearson's correlation and regression analysis. A paired t test was used to compare the postoperative outcomes. Subjectively, all patient results were satisfactory. There were significant differences between preoperative and postoperative measurements for all variables for total leg sculpture. Body mass index was strongly correlated with all leg indexes, and there was a significant positive correlation between the index and variables related to the buttocks and upper thigh. The satisfactory postoperative leg variables were buttocks circumference (87.85 cm), thigh circumference (T60, 44.20 cm), maximal calf circumference (32.24 cm), and calf ratio (0.78). Each preoperative body mass index increment represents a 0.3 percent circumference improvement around the buttocks after surgery. No obvious morbidities or long-term hospital stays were noted. Total leg sculpture provides a combined aesthetic solution for improving limb contours with minimal morbidity. Patients with larger body mass index values exhibit better aesthetic improvement than those with smaller values.

  10. Longitudinal fasting blood glucose patterns and arterial stiffness risk in a population without diabetes.

    Science.gov (United States)

    Wu, Yuntao; Yu, Junxing; Jin, Cheng; Li, Yun; Su, Jinmei; Wei, Guoqing; Zheng, Xiaoming; Gao, Jingsheng; Gao, Wenyuan; Wu, Shouling

    2017-01-01

    To identify long-term fasting blood glucose trajectories and to assess the association between the trajectories and the risk of arterial stiffness in individuals without diabetes. We enrolled 16,454 non-diabetic participants from Kailuan cohort. Fasting blood glucose concentrations were measured in 2006, 2008, and 2010 survey. Brachial-ankle pulse wave velocities were measured during 2011 to 2016. Multivariate regression model was used to estimate the difference of brachial-ankle pulse wave velocity levels and logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (95%CIs) of arterial stiffness risk, according to the fasting blood glucose trajectories. We identified five distinct fasting blood glucose trajectories and each of the trajectories was labeled according to its range and change over 2006-2010 survey: elevated-stable pattern (5.0% of participants), elevated-decreasing pattern (6.6%), moderate-increasing pattern (10.9%), moderate-stable pattern (59.3%), and low-stable pattern (18.2%). After adjustment for potential confounders, individuals with elevated-stable pattern had a 42.6 cm/s (95%CI: 24.7 to 60.6 cm/s) higher brachial-ankle pulse wave velocity level and a 37% (OR 1.37, 95%CI: 1.14 to 1.66) higher arterial stiffness risk, and individuals with moderate-increasing pattern had a 19.6 cm/s (95%CI: 6.9 to 32.3 cm/s) higher brachial-ankle pulse wave velocity level and a 17% (OR 1.17, 95%CI: 1.03 to 1.33) higher arterial stiffness risk, related to individuals with moderate-stable pattern. We did not find significant associations of the elevated-decreasing or low-stable patterns with arterial stiffness. Consistently, the cumulative average, variability, and increased rate of fasting blood glucose during 2006-2010 survey were significantly associated with the arterial stiffness risk. Discrete fasting blood glucose trajectories were associated with the arterial stiffness risk in non-diabetic individuals.

  11. Botulinum toxin in post-stroke patients: stiffness modifications and clinical implications.

    Science.gov (United States)

    Miscio, Giacinta; Del Conte, Carmen; Pianca, Danilo; Colombo, Roberto; Panizza, Marcela; Schieppati, Marco; Pisano, Fabrizio

    2004-02-01

    To objectively quantify stiffness and clinical changes in the upper limb of poststroke patients following botulinum toxin (BT) injection. Eighteen consecutive chronic post-stroke spastic patients were injected Botulinum toxin A in the forearm flexor spastic muscles. Spasticity was clinically evaluated with the Ashworth scale. Stiffness was measured with indices (passive stiffness index (ISI) and total stiffness index (TSI) obtained by mechanical wrist displacements induced by a torque motor,which could also provide the stretch reflex threshold speed (SRTS) from flexor muscles. Functional status was measured with the Barthel index and a specific hand ability scale, pain with a visual analogue scale (VAS). The ranges of voluntary wrist extension (EROM) and flexion (FROM) and wrist isometric extension and flexion (IE-IF) strength were also calculated. IE and EROM significantly increased, being respectively p < 0.01 and p < 0.05; also SRTS was augmented (p < 0.001),while TSI showed lower values (p < 0.001); the Ashworth score decreased at least one point. Hand function for selected tasks improved in 50% of patients, the Barthel index only in 4 (22 %), forearm pain was completely relieved in 3 patients (17 %). BT can be considered a valid therapeutic tool in all spastic patients, because of immediate advantages: reduction of muscle hypertonia, pain relief, improvement in selected motor performances.

  12. Physical deposition behavior of stiff amphiphilic polyelectrolytes in an external electric field

    Science.gov (United States)

    Hu, Dongmei; Zuo, Chuncheng; Cao, Qianqian; Chen, Hongli

    2017-08-01

    Coarse-grained molecular dynamics simulations are conducted to study the physical deposition behavior of stiff amphiphilic polyelectrolytes (APEs) in an external electric field. The effects of chain stiffness, the charge distribution of a hydrophilic block, and electric field strength are investigated. Amphiphilic multilayers, which consist of a monolayer of adsorbed hydrophilic monomers (HLMs), a hydrophobic layer, and another hydrophilic layer, are formed in a selective solvent. All cases exhibit locally ordered hydrophilic monolayers. Two kinds of hydrophobic micelles are distinguished based on local structures. Stripe and network hydrophobic patterns are formed in individual cases. Increasing the chain stiffness decreases the thickness of the deposited layer, the lateral size of the hydrophobic micelles, and the amount of deposition. Increasing the number of positively charged HLMs in a single chain has the same effect as increasing chain stiffness. Moreover, when applied normally to the substrate, the electric field compresses the deposited structures and increases the amount of deposition by pulling more PEs toward the substrate. A stronger electric field also facilitates the formation of a thinner and more ordered hydrophilic adsorption layer. These estimates help us explore how to tailor patterned nano-surfaces, nano-interfaces, or amphiphilic nanostructures by physically depositing semi-flexible APEs which is of crucial importance in physical sciences, life sciences and nanotechnology.

  13. Effect of Shoes on Stiffness and Energy Efficiency of Ankle-Foot Orthosis: Bench Testing Analysis.

    Science.gov (United States)

    Kobayashi, Toshiki; Gao, Fan; LeCursi, Nicholas; Foreman, K Bo; Orendurff, Michael S

    2017-12-01

    Understanding the mechanical properties of ankle-foot orthoses (AFOs) is important to maximize their benefit for those with movement disorders during gait. Though mechanical properties such as stiffness and/or energy efficiency of AFOs have been extensively studied, it remains unknown how and to what extent shoes influence their properties. The aim of this study was to investigate the effect of shoes on stiffness and energy efficiency of an AFO using a custom mechanical testing device. Stiffness and energy efficiency of the AFO were measured in the plantar flexion and dorsiflexion range, respectively, under AFO-alone and AFO-Shoe combination conditions. The results of this study demonstrated that the stiffness of the AFO-Shoe combination was significantly decreased compared to the AFO-alone condition, but no significant differences were found in energy efficiency. From the results, we recommend that shoes used with AFOs should be carefully selected not only based on their effect on alignment of the lower limb, but also their effects on overall mechanical properties of the AFO-Shoe combination. Further study is needed to clarify the effects of differences in shoe designs on AFO-Shoe combination mechanical properties.

  14. Discrete computational mechanics for stiff phenomena

    KAUST Repository

    Michels, Dominik L.

    2016-11-28

    Many natural phenomena which occur in the realm of visual computing and computational physics, like the dynamics of cloth, fibers, fluids, and solids as well as collision scenarios are described by stiff Hamiltonian equations of motion, i.e. differential equations whose solution spectra simultaneously contain extremely high and low frequencies. This usually impedes the development of physically accurate and at the same time efficient integration algorithms. We present a straightforward computationally oriented introduction to advanced concepts from classical mechanics. We provide an easy to understand step-by-step introduction from variational principles over the Euler-Lagrange formalism and the Legendre transformation to Hamiltonian mechanics. Based on such solid theoretical foundations, we study the underlying geometric structure of Hamiltonian systems as well as their discrete counterparts in order to develop sophisticated structure preserving integration algorithms to efficiently perform high fidelity simulations.

  15. Therapeutic advances in restless legs syndrome (RLS).

    Science.gov (United States)

    Högl, Birgit; Comella, Cynthia

    2015-09-15

    Levodopa and dopamine agonists have been the main treatment for restless legs syndrome during the past decades. Although their efficacy has been well documented over the short term, long-term dopaminergic treatment is often complicated by augmentation, loss of efficacy, and other side effects. Recent large randomized controlled trials provide new evidence for the efficacy of high-potency opioids and α2δ ligands, and several post hoc analyses, meta-analyses, algorithms, and guidelines have been published, often with a specific focus, for example, on augmentation, or on management of restless legs syndrome during pregnancy. Several new contributions to understanding the pathophysiology of restless legs syndrome have been published, but at this time, whether they will have an impact on treatment possibilities in the future cannot be estimated. © 2015 International Parkinson and Movement Disorder Society.

  16. Conjoined legs: Sirenomelia or caudal regression syndrome?

    Directory of Open Access Journals (Sweden)

    Sakti Prasad Das

    2013-01-01

    Full Text Available Presence of single umbilical persistent vitelline artery distinguishes sirenomelia from caudal regression syndrome. We report a case of a12-year-old boy who had bilateral umbilical arteries presented with fusion of both legs in the lower one third of leg. Both feet were rudimentary. The right foot had a valgus rocker-bottom deformity. All toes were present but rudimentary. The left foot showed absence of all toes. Physical examination showed left tibia vara. The chest evaluation in sitting revealed pigeon chest and elevated right shoulder. Posterior examination of the trunk showed thoracic scoliosis with convexity to right. The patient was operated and at 1 year followup the boy had two separate legs with a good aesthetic and functional results.

  17. The pathophysiology of restless legs syndrome

    International Nuclear Information System (INIS)

    Miyamoto, Masayuki; Miyamoto, Tomoyuki; Iwanami, Masaoki; Suzuki, Keisuke; Hirata, Koichi

    2009-01-01

    Restless legs syndrome (RLS) is a sensorimotor disorder that is frequently associated with periodic leg movements (PLMS). RLS is generally considered to be a central nervous system (CNS)-related disorder although no specific lesion has been found to be associated with the syndrome. Reduced intracortical inhibition has been demonstrated in RLS by transcranial magnetic stimulation. Some MRI studies have revealed the presence of morphologic changes in the somatosensory cortex, motor cortex and thalamic gray matter. The results of single photon emission computed tomography (SPECT) and positron emission tomography (PET) studies showed that the limbic and opioid systems also play important roles in the pathophysiology of RLS. A functional MRI study revealed abnormal bilateral cerebellar and thalamic activation during the manifestation of sensory symptoms, with additional red nucleus and reticular formation activity during PLMS. PLMS is likely to occur in patients with spinal cord lesions, and some patients with sensory polyneuropathy may exhibit RLS symptoms. RLS symptoms seem to depend on abnormal spinal sensorimotor integration at the spinal cord level and abnormal central somatosensory processing. PLMS appears to depend on increased excitability of the spinal cord and a decreased supraspinal inhibitory mechanism from the A11 diencephalic dopaminergic system. RLS symptoms respond very dramatically to dopaminergic therapy. The results of analysis by PET and SPECT studies of striatal D2 receptor binding in humans are inconclusive. However, studies in animal models suggest that the participation of the A11 dopaminergic system and the D3 receptor in RLS symptoms. The symptoms of RLS are aggravated in those with iron deficiency, and iron treatment ameliorates the symptoms in some patients. Neuroimaging studies, analysis of the cerebrospinal fluid, and studies on postmortem tissue and use of animal models have indicated that low brain iron concentrations and dysfunction of

  18. Effect of sex and fatigue on muscle stiffness and musculoarticular stiffness of the knee joint in a young active population.

    Science.gov (United States)

    Wang, Dan; De Vito, Giuseppe; Ditroilo, Massimiliano; Delahunt, Eamonn

    2017-08-01

    The purpose of this study was to investigate the influence of sex and fatigue on knee extensor peak torque (PT), muscle stiffness (MS) of the vastus lateralis (VL) and knee joint musculoarticular stiffness (MAS) in young adults. Twenty-two male and 22 female recreational athletes participated. Males were characterised by higher relaxed [pre-: males 364.43 (52.00) N · m -1 , females 270.27 (37.25) N · m -1 ; post-: males 446.75 (83.27) N · m -1 , females 307.39 (38.58) N · m -1 ] and contracted [pre-: males 495.07 (71.04) N · m -1 , females 332.34 (85.42) N · m -1 ; post-: males 546.37 (90.74) N · m -1 , females 349.21 (85.55) N · m -1 ] MS of the VL, and knee joint MAS [pre-: males 1450.11 (507.98) N · m -1 , females 1027.99 (227.33) N · m -1 ; post-: males 1345.81 (404.90) N · m -1 , females 952.78 (192.38) N · m -1 ] than females pre- and post-fatigue. A similar finding was observed in pre-fatigue normalised knee extensor PT [pre-: males 2.77 (0.42) N · m kg -1 , females 2.41 (0.40) N · m kg -1 , post-: males 2.53 (0.54) N · m kg -1 , females 2.26 (0.44) N · m kg -1 ]. After the fatigue protocol, normalised knee extensor PT and knee joint MAS decreased, whilst relaxed and contracted MS of the VL increased in both sexes. These observed differences may contribute to the higher risk of knee injury in females and following the onset of fatigue.

  19. Arthroscopic capsular release for refractory shoulder stiffness

    Directory of Open Access Journals (Sweden)

    Marcos Rassi Fernandes

    2013-08-01

    Full Text Available OBJECTIVE: To evaluate the results of the arthroscopic treatment of refractory adhesive capsulitis of the shoulder with two to nine years of follow-up, comparing the pre-and postoperative range of motion. METHODS: This was an observational study (case series of 18 patients who underwent arthroscopic capsular release for refractory shoulder stiffness. The mean age was of 53.6 years (range: 39 to 68, with female predominance (77.77% and nine cases left shoulders. There were 6 primary (33.33% and 12 secondary cases (66.67%. Arthroscopic capsular release was performed in all patients after a mean of 9.33 months of physical therapy (range: 6 to 20 months with a minimum follow-up of two years (range: 26 to 110 months. RESULTS: The mean active and passive forward flexion, external rotation and internal rotation increased from 94.4º/103.3º, 11.9º/21.9º, and S1/L5 vertebral level, respectively, to 151.1º/153.8º, 57.2º/64.4º, and T12/T10 vertebral level, respectively. There was a significant difference between the pre-and postoperative range of motion (p < 0.001. according to the constant-murley functional score (rom, the value increased from 14 (preoperative mean to 30 points (postoperative mean. postoperatively, all patients showed diminished shoulder pain (none or mild/15 or 10 points in the constant-murley score. CONCLUSION: arthroscopic treatment is an effective treatment for refractory shoulder stiffness.

  20. Leg Spasticity and Ambulation in Multiple Sclerosis

    Directory of Open Access Journals (Sweden)

    Swathi Balantrapu

    2014-01-01

    Full Text Available Background. Spasticity of the legs is common in multiple sclerosis (MS, but there has been limited research examining its association with ambulatory outcomes. Objective. This study examined spasticity of the legs and its association with multiple measures of ambulation in persons with MS. Methods. The sample included 84 patients with MS. Spasticity of the legs was measured using a 5-point rating scale ranging between 0 (normal and 4 (contracted. Patients completed the 6-minute walk (6 MW, timed 25 foot walk (T25FW, and timed up-and-go (TUG, and O2 cost of walking was measured during the 6 MW. The patients undertook two walking trials on a GAITRite (CIR systems, Inc. for measuring spatial and temporal parameters of gait. The patients completed the Multiple Sclerosis Walking Scale-12 (MSWS-12 and wore an accelerometer over a seven-day period. Results. 52% (n=44 of the sample presented with spasticity of the legs. Those with leg spasticity had significantly worse ambulation as measured by 6 MW (P=0.0001, d=-0.86, T25FW (P=0.003,d=0.72, TUG (P=0.001, d=0.84, MSWS-12 (P=0.0001,d=1.09, O2 cost of walking (P=0.001, d=0.75, average steps/day (P<0.05, d=-0.45, and walking velocity (P<0.05, d=-0.53 and cadence (P<0.05, d=-0.46. Conclusion. Leg spasticity was associated with impairments in ambulation, including alterations in spatiotemporal parameters and free-living walking.

  1. Pulling a polymer with anisotropic stiffness near a sticky wall

    International Nuclear Information System (INIS)

    Tabbara, R; Owczarek, A L

    2012-01-01

    We solve exactly a two-dimensional partially directed walk model of a semi-flexible polymer that has one end tethered to a sticky wall, while a pulling force away from the adsorbing surface acts on the free end of the walk. This model generalizes a number of previously considered adsorption models by incorporating individual horizontal and vertical stiffness effects, in competition with a variable pulling angle. A solution to the corresponding generating function is found by means of the kernel method. While the phases and related phase transitions are similar in nature to those found previously the analysis of the model in terms of its physical variables highlights various novel structures in the shapes of the phase diagrams and related behaviour of the polymer. We review the results of previously considered sub-cases, augmenting these findings to include analysis with respect to the model’s physical variables—namely, temperature, pulling force, pulling angle away from the surface, stiffness strength and the ratio of vertical to horizontal stiffness potentials, with our subsequent analysis for the general model focusing on the effect that stiffness has on this pulling angle range. In analysing the model with stiffness we also pay special attention to the case where only vertical stiffness is included. The physical analysis of this case reveals behaviour more closely resembling that of an upward pulling force acting on a polymer than it does of a model where horizontal stiffness acts. The stiffness–temperature phase diagram exhibits re-entrance for low temperatures, previously only seen for three-dimensional or co-polymer models. For the most general model we delineate the shift in the physical behaviour as we change the ratio of vertical to horizontal stiffness between the horizontal-only and the vertical-only stiffness regimes. We find that a number of distinct physical characteristics will only be observed for a model where the vertical stiffness dominates

  2. THE EFFECT OF GOLIMUMAB ON ARTERIAL STIFFNESS IN PATIENTS WITH RHEUMATOID ARTHRITIS

    Directory of Open Access Journals (Sweden)

    L. A. Knyazeva

    2018-01-01

    Full Text Available Objective: to evaluate the effect of golimumab (GLM on arterial stiffness in patients with different clinical and immunological subtypes of rheumatoid arthritis (RA.Material and methods. Examinations were made in 48 patients with RA meeting the 1987 ACR/2010 EULAR classification criteria. The investigators visualized carotid arteries with determination of local vessel wall stiffness and studied regional arterial stiffness with assessment of contour pulse wave analysis before and 52 weeks after initiation of therapy.Results and discussion. Young and middle-aged RA patients without any concomitant cardiovascular diseases were found to have subclinical great artery involvement that was characterized by increases in intima-media thickness (IMT and stiffness index β of the common carotid artery (CCA; by rises in peripheral augmentation index (AIp, stiffness index (SI, and reflection index (RI, the intensity of a change in which was associated with high DAS28 and seropositivity for rheumatoid factor (RF and/or anti-cyclic citrullinated peptide (antiCCP antibodies. GLM treatment in patients with RA was accompanied by a statistically significant decrease in DAS28 and a reduction in CCA IMT and local (carotid stiffness of the vascular bed. More significant correction of the investigated parameters was achieved in patients with the seronegative subtype of the disease; in this group of patients, CCA IMT decreased by 29% by the end of observation (p=0.01, CCA SI β reduced by an average of 28.7% (p=0.0001. At 52 weeks after GLM therapy initiation, contour pulse wave analysis indicated that this subgroup of patients was observed to have decreases in AIp, SI, and RI to the control level; in RA seropositive for RF and/or anti-CCP, they reduced by an average of 1.8 (p=0.0001, 1.2 (p=0.005 and 1.6 (p=0.001 times, respectively.Conclusion. Along with high anti-inflammatory activity, GLM therapy in patients with RA has a vasoprotective effect on the walls of large

  3. Changes on Tendon Stiffness and Clinical Outcomes in Athletes Are Associated With Patellar Tendinopathy After Eccentric Exercise.

    Science.gov (United States)

    Lee, Wai-Chun; Ng, Gabriel Yin-Fat; Zhang, Zhi-Jie; Malliaras, Peter; Masci, Lorenzo; Fu, Siu-Ngor

    2017-12-19

    Eccentric exercise is commonly used as a form of loading exercise for individuals with patellar tendinopathy. This study investigated the change of mechanical properties and clinical outcomes and their interrelationships after a 12-week single-legged decline-board exercise with and without extracorporeal shockwave therapy (ESWT). Randomized controlled trial. Outpatient clinic of a university. Thirty-four male in-season athletes with patellar tendinopathy for more than 3 months were randomized into exercise and combined groups. The exercise group received a 12-week single-legged decline-squat exercise, and the combined group performed an identical exercise program in addition to a weekly session of ESWT in the initial 6 weeks. Tendon stiffness and strain were examined using ultrasonography and dynamometry. Visual analog scale and Victoria Institute of Sports Assessment-patella (VISA-p) score were used to assess pain and dysfunction. These parameters were measured at preintervention and postintervention. Significant time effect but no significant group effect on the outcome measures; significant reduction in tendon stiffness (P = 0.02) and increase in tendon strain (P = 0.00); and reduction of intensity of pain (P = 0.00) and dysfunction (P = 0.00) were observed. Significant correlations between changes in tendon stiffness and VISA-p score (ρ = -0.58, P = 0.05); alteration in tendon strain, pain intensity (ρ = -0.63, P = 0.03); and VISA-p score (ρ = 0.60, P = 0.04) were detected after the exercise program. Eccentric exercise-induced modulation on tendon mechanical properties and clinical symptoms are associated in athletes with patellar tendinopathy.

  4. The Molecular Genetics of Restless Legs Syndrome.

    Science.gov (United States)

    Rye, David B

    2015-09-01

    Restless legs syndrome (RLS) is a common sensorimotor trait defined by symptoms that interfere with sleep onset and maintenance in a clinically meaningful way. Nonvolitional myoclonus while awake and asleep is a sign of the disorder and an informative endophenotype. The genetic contributions to RLS/periodic leg movements are substantial, are among the most robust defined to date for a common disease, and account for much of the variance in disease expressivity. The disorder is polygenic, as revealed by recent genome-wide association studies. Experimental studies are revealing mechanistic details of how these common variants might influence RLS expressivity. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Nocturnal leg cramps in older people

    Science.gov (United States)

    Butler, J; Mulkerrin, E; O'Keeffe, S

    2002-01-01

    Nocturnal leg cramps are common in older people. Such cramps are associated with many common diseases and medications. Physiological methods may be useful for preventing cramps in some people, but there have been no controlled trials of these approaches. Quinine is moderately effective in preventing nocturnal leg cramps. However, there are concerns about the risk/benefit ratio with this drug. In patients with severe symptoms, a trial of 4–6 weeks' treatment with quinine is probably still justified, but the efficacy of treatment should be monitored, for example using a sleep and cramp diary. PMID:12415081

  6. The development of a 'wet leg' pathway for chronic oedema.

    Science.gov (United States)

    Morgan, Karen; Thomas, Melanie

    2018-01-02

    Chronic oedema and leaking lymphorrhoea can be distressing and challenging for patients to live with. This article introduces the Chronic Oedema 'Wet Leg' Pathway, which became an output from the Lymphoedema Network Wales 'On the Ground Education Project' ( Thomas et al, 2017 ). The evidence-based pathway provides nurses and therapists with clear guidelines to support prompt, efficient and effective management of all patients with chronic oedema and wet legs. This article presents the evidence and demonstrates the benefits of timely active treatment for all patients with leaking lymphorrhoea, which includes decreasing pain and improving mobility and daily activities. Other benefits include reducing the risk of cellulitis and the development of chronic wounds. The pathway also demonstrates opportunities for the NHS by decreasing both the number of community nursing visits and the number of wound dressings used. By actively treating symptoms-rather than simply mopping up the leaking lymphorrhoea-this pathway demonstrates value-based health care by reducing waste, harm and variation within the NHS.

  7. Leg ulcer plastic surgery descent by laser therapy

    Science.gov (United States)

    Telfer, Jacqui; Filonenko, Natalia; Salansky, Norman M.

    1994-02-01

    Low energy laser therapy (LELT) was used to treat chronic leg ulcers. Seven patients, aged 59 to 96 years, with 11 leg ulcers were referred for laser therapy by plastic surgeons. They had a history of ulceration of 3 - 50 years and five of the patients had breakdown of previous skin grafts. Laser treatments were administered with a microprocessor-controlled device. A 22 red ((lambda) equals 660 nm) laser head was utilized to provide a dose of (4 - 6) J/cm2 and 7 infrared ((lambda) equals 880 nm) head to provide a dose of (4 - 8) J/cm2. The patients were treated three to five times per week, 25 - 30 treatments per course. Three patients underwent two courses of laser therapy with three weeks interval between them. All patients, after 5 - 10 laser treatments, have gotten relief of pain and decreased the amount of analgesics used. All ulcers in six patients were completely healed and two ulcers in the seventh patient decreased in size by 75%. One may conclude the developed laser methodology might be used as a preventative measure to avoid plastic surgery or improve its success.

  8. Comparison of thorasis kyphosis and postural stiffness between elderly females and males in Tehran elderly recreation association

    Directory of Open Access Journals (Sweden)

    Minoo Khalkhali zavieh

    2013-01-01

    Full Text Available Background and Aim: Hyperkyphosis can lead to reduced respiratory capacity, postural disturbance and increased risk of falling. Despite the evidences about the more postural stiffness and kyphosis in elderly compared with young subjects and despite the known role of sex hormones and menopause in lowering the bone density, there is not any study about the effect of sex on the amount of thoracic kyphosis. The objective of this study is measuring and comparing the amount of spinal thoracic kyphosis and postural stiffness between the old females and males.Methods and Materials: In this descriptive-analytical study, in 36 healthy old subjects (21 female and 15 male the amount of spinal thoracic kyphosis was measured by flexible ruler mounted between the spinous process T12 and C7 during, relaxed and erect postures. The difference of the kyphosis in relaxed and erect posture was used as an index of postural stiffness. The kyphosis and postural stiffness was compared between the females and males.Results: The average amount of kyphosis in relaxed and erect standing didn’t have statistically significant difference between females and males. The subjects in both groups could decrease theirs kyphosis in standing erect position (P=0.0001, but the amount of this decrease (postural stiffness was not different between the females and males. Conclusion: In old women (which aren’t osteoporotic hormonal changes due to menopause didn’t induce a statistically significant difference compared to old men in kyphosis and postural stiffness.Postural stiffness was increased by increasing the BMI that could suggest the BMI as an efficient factor in reducing the mobility of the spine.

  9. THE EFFECTS OF SINGLE LEG HOP PROGRESSION AND DOUBLE LEGS HOP PROGRESSION EXERCISE TO INCREASE SPEED AND EXPLOSIVE POWER OF LEG MUSCLE

    Directory of Open Access Journals (Sweden)

    Nining W. Kusnanik

    2015-05-01

    Full Text Available The main purpose of this study was to determine the effect of single leg hop progression and double legs hop progression exercise to increase speed and explosive power of leg muscles. Plyometric is one of the training methods that can increase explosive power. There are many models of plyometric training including single leg hop progression and double leg hop progression. This research was experimental using match subject design techniques. The subjects of this study were 39 students who joined basketball school club. There were 3 groups in this study: Group 1 were 13 students who given sin¬gle leg hop progression exercise, Group 2 were 13 students who given double legs hop progression exercise, Group 3 were 13 students who given conventional exercise. The data was collected during pre test and post test by testing 30m speed running and vertical jump. The data was analyzed using Analysis of Varians (Anova. It was found that there were significantly increased on speed and explosive power of leg muscles of Group 1 and Group 2. It can be stated that single leg hop progression exercise was more effective than double leg hop progression exercise. The recent findings supported the hypothesis that single leg hop progression and double legs hop progression exercise can increase speed and explosive power of leg muscles. These finding were supported by some previous studies (Singh, et al, 2011; Shallaby, H.K., 2010. The single leg hop progression is more effective than double legs hop progression. This finding was consistent with some previous evidences (McCurdy, et al, 2005; Makaruk et al, 2011.

  10. Clinical characteristics of leg restlessness in Parkinson's disease compared with idiopathic Restless Legs Syndrome.

    Science.gov (United States)

    Zhu, Xiao-Ying; Liu, Ye; Zhang, Xiao-Jin; Yang, Wen-Hao; Feng, Ya; Ondo, William G; Tan, Eng-King; Wu, Yun-Cheng

    2015-10-15

    There is limited data on motor restlessness in Parkinson's disease (PD). Here we evaluate for clinical differences between cohorts of idiopathic Restless Legs Syndrome (iRLS), PD patients with leg restlessness, and PD with RLS. We examined 276 consecutive PD patients for leg restlessness symptoms, we compared clinical features of PD patients with RLS, PD patients with leg restlessness but not meeting RLS criteria, PD patient without RLS and iRLS. A total of 262 PD patients who satisfied the inclusion criteria were analyzed. After excluding 23 possible secondary RLS or mimics, 28 were diagnosed with RLS and 18 with leg motor restlessness (LMR). Compared with iRLS patients, PD patients with RLS or LMR had older age of RLS/LMR onset, shorter duration of leg restlessness, less positive family history, different seasonal trends and more unilaterality of leg restlessness symptom (Pleg restlessness. PD with LMR had less severe Parkinsonism (Pleg restlessness (P<0.01) symptoms than PD with RLS. Clinical characteristics of PD patients with RLS and LMR were different from iRLS, differentiating these various subtypes can facilitate optimal treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Task driven optimal leg trajectories in insect-scale legged microrobots

    Science.gov (United States)

    Doshi, Neel; Goldberg, Benjamin; Jayaram, Kaushik; Wood, Robert

    Origami inspired layered manufacturing techniques and 3D-printing have enabled the development of highly articulated legged robots at the insect-scale, including the 1.43g Harvard Ambulatory MicroRobot (HAMR). Research on these platforms has expanded its focus from manufacturing aspects to include design optimization and control for application-driven tasks. Consequently, the choice of gait selection, body morphology, leg trajectory, foot design, etc. have become areas of active research. HAMR has two controlled degrees-of-freedom per leg, making it an ideal candidate for exploring leg trajectory. We will discuss our work towards optimizing HAMR's leg trajectories for two different tasks: climbing using electroadhesives and level ground running (5-10 BL/s). These tasks demonstrate the ability of single platform to adapt to vastly different locomotive scenarios: quasi-static climbing with controlled ground contact, and dynamic running with un-controlled ground contact. We will utilize trajectory optimization methods informed by existing models and experimental studies to determine leg trajectories for each task. We also plan to discuss how task specifications and choice of objective function have contributed to the shape of these optimal leg trajectories.

  12. Robust Position Control of End-Effector Considering Gear Stiffness and Arm Stiffness for Industrial Robot

    Science.gov (United States)

    Tungpataratanawong, Somsawas; Chitbanchong, Satit; Miyazaki, Toshimasa; Katsura, Seiichiro; Ohishi, Kiyoshi

    Industrial robot with two-inertia model and resonant vibration suppression by using parameters from resonant identification method are addressed in this paper. By using only D-PD control with vibration suppression scheme for two-inertia model of flexible joint robot, the end-effector position does not perfectly reach the desired position owing to the effect of external force to the elastic arm. However, only gear stiffness parameter of two-inertia model is not enough, the new equivalent spring constant parameter including the stiffness of link and gear of the robot is introduced as the total arm spring constant. The novel load-side disturbance compensation considering total arm elasticity is proposed in this paper. The proposed control system is based on inner-loop vibration suppression feedback control and load-side disturbance suppression which motivates the simple consideration of the elastic joint under external torque. Moreover, the experimental results show the effectiveness of the proposed robust position control of end-effector with disturbance compensation considering total arm stiffness. The experimentation on workspace impedance control with inner-loop disturbance suppression implementing on the three degree-of-freedom (3-DOF) robot manipulator is also presented and discussed. The performance and feasibility of the proposed position control of end-effector is confirmed to apply to industrial robot manipulator without additional device.

  13. Optimization of a quasi-zero-stiffness isolator

    International Nuclear Information System (INIS)

    Carrella, A.; Brennan, M. J.; Waters, T. P.

    2007-01-01

    The frequency range over which a mount can isolate a mass from a vibrating base (or vice versa) is often limited by the mount stiffness required to support the weight of the mass. This compromise can be made more favourable by employing non-linear mounts with a softening spring characteristic such that small excursions about the static equilibrium position result in small dynamic spring forces and a correspondingly low natural frequency. This paper concerns the force-displacement characteristic of a so-called quasi-zero-stiffness (QZS) mechanism which is characterised by an appreciable static stiffness but very small (theoretically zero) dynamic stiffness. The mechanism studied comprises a vertical spring acting in parallel with two further springs which, when inclined at an appropriate angle to the vertical, produce a cancelling negative stiffness effect. Analysis of the system shows that a QZS characteristic can be obtained if the systems parameters (angle of inclination and ratio of spring stiffness) are opportunely chosen. By introducing the additional criterion that the displacement of the system be largest without exceeding a desired (low) value of stiffness an optimal set of parameter values is derived. Under sufficiently large displacements the stiffness of the QZS mechanism can eventually exceed that of the simple mass-spring system and criteria for this detrimental scenario to arise are presented

  14. Current front stiffness of European vehicles with regard to compatibility

    NARCIS (Netherlands)

    Huibers, J.; Beer, E. de

    2001-01-01

    EuroNCAP tests are carried out since 1997. The test procedure in general is comparable to the EC Directive 96/79 with a test speed of 64 km/h. This increased test speed implies a higher frontal stiffness for new vehicle designs in order to achieve a high ranking. This frontal stiffness is one of the

  15. A novel stiffness control method for series elastic actuator

    Science.gov (United States)

    Lin, Guangmo; Zhao, Xingang; Han, Jianda

    2017-01-01

    Compliance plays an important role in human-robot cooperation. However, fixed compliance, or fixed stiffness, is difficult to meet the growing needs of human machine collaboration. As a result, the robot actuator is demanded to be able to adjust its stiffness. This paper presents a stiffness control scheme for a single DOF series elastic actuator (SEA) with a linear spring mounted in series in the mechanism. In this proposed method, the output angle of the spring is measured and used to calculate the input angle of the spring, thus the equivalent stiffness of the robot actuator revealed to the human operator can be rendered in accordance to the desired stiffness. Since the techniques used in this method only involve the position information of the system, there is no need to install an expensive force/torque sensor on the actuator. Further, the force/torque produced by the actuator can be estimated by simply multiplying the deformation angle of the spring and its constant stiffness coefficient. The analysis of the stiffness controller is provided. Then a simulation that emulates a human operates the SEA while the stiffness controller is running is carried out and the results also validate the proposed method.

  16. A fourth order exponentially-fitted multiderivative method for Stiff ...

    African Journals Online (AJOL)

    A fourth order exponentially-fitted multiderivative method for Stiff initial value problems. ... Journal of the Nigerian Association of Mathematical Physics ... implemented and preliminary numerical results indicate that the approach compares favourably with other existing methods that have solved the same set of stiff problems.

  17. Association of Parental Hypertension With Arterial Stiffness in Nonhypertensive Offspring

    DEFF Research Database (Denmark)

    Andersson, Charlotte; Quiroz, Rene; Enserro, Danielle

    2016-01-01

    High arterial stiffness seems to be causally involved in the pathogenesis of hypertension. We tested the hypothesis that offspring of parents with hypertension may display higher arterial stiffness before clinically manifest hypertension, given that hypertension is a heritable condition. We compa...

  18. Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

    Science.gov (United States)

    Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

    2015-07-21

    Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

  19. Stiffness as a control variable in motor performance

    NARCIS (Netherlands)

    Vincken, M.H.; Denier van der Gon, J.J.

    1985-01-01

    In the experiments described in this article we investigated the control of stiffness of the effector system in relation to parameters of the movement. If the velocity of a movement is chosen, it appears that at the same time the stiffness of the effector system is set to a preferred value. By

  20. Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

    2017-10-17

    Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

  1. [The influence of the leg load and the support mobility under leg on the anticipatory postural adjustment].

    Science.gov (United States)

    Kazennikov, O V; Kireeva, T B; Shlykov, V Iu

    2015-01-01

    Anticipatory postural adjustment is an essential part of equilibrium maintainance during standing in human. So changes in stance condition could affect both control of equilibrium and anticipatory adjustment. Anticipatory changes in the stabilogram of each leg were studied in standing subject during the early stage of quick right arm lifting while legs were on two separated supports. The center of pressure (CP) movement was analyzed in three variants of experiment: both legs on immovable support, with only right leg on the movable support and with only left leg on the moveable support. In each standing condition subject stood with symmetrical load on two legs or with the load voluntary transferred to one leg. The anticipatory CP shift depended on the mobility of the support under the leg and on loading of the leg. While standing on unmovable supports with symmetrical load on the legs before lifting of the right arm CP of right leg shifted backward and CP of left leg--forward. While standing with one leg on movable support the anticipatory CP shift of this leg was small and did not depend on the load on the leg. However the shift of CP of the leg that was placed on the unmovable support depended on the load in the same way as in the case when both legs were on unmovable supports. Results suggested that since on movable support the support and proprioceptive afferent flow from distal part of the leg that was did not supply unambiguous information about body position, the role of distal joints in posture control is reduced.

  2. Kinematic and kinetic comparisons of transfemoral amputee gait using C-Leg and Mauch SNS prosthetic knees.

    Science.gov (United States)

    Segal, Ava D; Orendurff, Michael S; Klute, Glenn K; McDowell, Martin L; Pecoraro, Janice A; Shofer, Jane; Czerniecki, Joseph M

    2006-01-01

    The C-Leg (Otto Bock, Duderstadt, Germany) is a microprocessor-controlled prosthetic knee that may enhance amputee gait. This intrasubject randomized study compared the gait biomechanics of transfemoral amputees wearing the C-Leg with those wearing a common noncomputerized prosthesis, the Mauch SNS (Ossur, Reykjavik, Iceland). After subjects had a 3-month acclimation period with each prosthetic knee, typical gait biomechanical data were collected in a gait laboratory. At a controlled walking speed (CWS), peak swing phase knee-flexion angle decreased for the C-Leg group compared with the Mauch SNS group (55.2 degrees +/- 6.5 degrees vs 64.41 degrees +/- 5.8 degrees , respectively; p = 0.005); the C-Leg group was similar to control subjects' peak swing knee-flexion angle (56.0 degrees +/- 3.4 degrees ). Stance knee-flexion moment increased for the C-Leg group compared with the Mauch SNS group (0.142 +/- 0.05 vs 0.067 +/- 0.07 N"m, respectively; p = 0.01), but remained significantly reduced compared with control subjects (0.477 +/- 0.1 N"m). Prosthetic limb step length at CWS was less for the C-Leg group compared with the Mauch SNS group (0.66 +/- 0.04 vs 0.70 +/- 0.06 m, respectively; p = 0.005), which resulted in increased symmetry between limbs for the C-Leg group. Subjects also walked faster with the C-Leg versus the Mauch SNS (1.30 +/- 0.1 vs 1.21 +/- 0.1 m/s, respectively; p = 0.004). The C-Leg prosthetic limb vertical ground reaction force decreased compared with the Mauch SNS (96.3 +/- 4.7 vs 100.3 +/- 7.5 % body weight, respectively; p = 0.0092).

  3. Insulin action in human thighs after one-legged immobilization

    DEFF Research Database (Denmark)

    Richter, Erik; Kiens, Bente; Mizuno, M.

    1989-01-01

    Insulin action was assessed in thighs of five healthy young males who had one knee immobilized for 7 days by a splint. The splint was not worn in bed. Subjects also used crutches to prevent weight bearing of the immobilized leg. Immobilization decreased the activity of citrate synthase and 3-OH......-acyl-CoA-dehydrogenase in the vastus lateralis muscle by 9 and 14%, respectively, and thigh volume by 5%. After 7 days of immobilization, a two-step euglycemic hyperinsulinemic clamp procedure combined with arterial and bilateral femoral venous catheterization was performed. Insulin action on glucose uptake and tyrosine release...... of the thighs at mean plasma insulin concentrations of 67 (clamp step I) and 447 microU/ml (clamp step II) was decreased by immobilization, whereas immobilization did not affect insulin action on thigh exchange of free fatty acids, glycerol, O2, or potassium. Before and during the clamp step I, lactate release...

  4. An automatic hinge system for leg orthoses

    NARCIS (Netherlands)

    Rietman, J. S.; Goudsmit, J.; Meulemans, D.; Halbertsma, J. P. K.; Geertzen, J. H. B.

    2004-01-01

    This paper describes a new automatic hinge system for leg orthoses, which provides knee stability in stance, and allows knee-flexion during swing. Indications for the hinge system are a paresis or paralysis of the quadriceps muscles. Instrumented gait analysis was performed in three patients, fitted

  5. An automatic hinge system for leg orthoses

    NARCIS (Netherlands)

    Rietman, J.S.; Goudsmit, J.; Meulemans, D.; Halbertsma, J.P.K.; Geertzen, J.H.B.

    This paper describes a new, automatic hinge system for leg orthoses, which provides knee stability in stance, and allows knee-flexion during swing. Indications for the hinge system are a paresis or paralysis of the quadriceps muscles. Instrumented gait analysis was performed in three patients,

  6. Chronic leg ulcer caused by Mycobacterium immunogenum

    NARCIS (Netherlands)

    Loots, Miriam A. M.; de Jong, Menno D.; van Soolingen, Dick; Wetsteyn, José C. F. M.; Faber, William R.

    2005-01-01

    Rare tropical skin diseases are seen more frequently in Western countries because of the increased popularity of visiting tropical regions. A 55-year-old white man developed a painless leg ulcer after traveling in Guatemala and Belize. A mycobacterium was cultured from a biopsy specimen and was

  7. X-Ray Exam: Femur (Upper Leg)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Femur (Upper Leg) KidsHealth / For Parents / X- ... Muscles, and Joints Broken Bones Getting an X-ray (Video) X-Ray (Video) View more Partner Message About Us ...

  8. The restless legs syndrome (Ekbom's syndrome)

    African Journals Online (AJOL)

    1983-04-30

    Apr 30, 1983 ... same distribution as the paraesthesiae; and (v) anxiety, tension or mild depression. Paraesthesiae or creeping sensations are usually confined to the calves. They are extremely unpleasant and deep-seated in muscles or bones rather than in the skin, mostly affecting the legs between the knee and ankle.

  9. Leg og læring

    DEFF Research Database (Denmark)

    Pedersen, Annette

    2008-01-01

    Leg synes at have et potentiale som metode til at fremme læring. Men hvordan? Legen har en vis grad af parallelitet med den virkelige verden i dens interaktive og relationelle strukturer. Det bliver muligt at finde nye meninger i interaktioner, som refererer til vante interaktionsformer, men...

  10. Functional scoliosis caused by leg length discrepancy

    Science.gov (United States)

    Daniszewska, Barbara; Zolynski, Krystian

    2010-01-01

    Introduction Leg length discrepancy (LLD) causes pelvic obliquity in the frontal plane and lumbar scoliosis with convexity towards the shorter extremity. Leg length discrepancy is observed in 3-15% of the population. Unequalized lower limb length discrepancy leads to posture deformation, gait asymmetry, low back pain and discopathy. Material and methods In the years 1998-2006, 369 children, aged 5 to 17 years (209 girls, 160 boys) with LLD-related functional scoliosis were treated. An external or internal shoe lift was applied. Results Among 369 children the discrepancy of 0.5 cm was observed in 27, 1 cm in 329, 1.5 cm in 9 and 2 cm in 4 children. During the first follow-up examination, within 2 weeks, the adjustment of the spine to new static conditions was noted and correction of the curve in 316 examined children (83.7%). In 53 children (14.7%) the correction was observed later and was accompanied by slight low back pain. The time needed for real equalization of limbs was 3 to 24 months. The time needed for real equalization of the discrepancy was 11.3 months. Conclusions Leg length discrepancy equalization results in elimination of scoliosis. Leg length discrepancy < 2 cm is a static disorder; that is why measurements should be performed in a standing position using blocks of adequate thickness and the position of the posterior superior iliac spine should be estimated. PMID:22371777

  11. Omnidirectional Wheel-Legged Hybrid Mobile Robot

    Directory of Open Access Journals (Sweden)

    István Vilikó

    2015-06-01

    Full Text Available The purpose of developing hybrid locomotion systems is to merge the advantages and to eliminate the disadvantages of different type of locomotion. The proposed solution combines wheeled and legged locomotion methods. This paper presents the mechatronic design approach and the development stages of the prototype.

  12. Parallel kinematics robot with five legs

    NARCIS (Netherlands)

    Lambert, P.

    2011-01-01

    Robot with multiple degrees of freedom comprising five legs (2) linked at a first of their ends to a base ( 3), and at a second of their ends opposite to the first ends to a mobile platform (4), which platform carries at least one tool (5, 6, 121, 12 "), and wherein the robot further comprises an

  13. Obstructive sleep apnea is associated with increased arterial stiffness in severe obesity.

    Science.gov (United States)

    Seetho, Ian W; Parker, Robert J; Craig, Sonya; Duffy, Nick; Hardy, Kevin J; Wilding, John P H

    2014-12-01

    Obstructive sleep apnea is associated with obesity and metabolic syndrome, leading to greater cardiovascular risk. Severely obese patients with obstructive sleep apnea may still be at risk of adverse health outcomes, even without previous cardiovascular disease. Pulse wave analysis non-invasively measures peripheral pulse waveforms and derives measures of haemodynamic status, including arterial stiffness, augmentation pressure and subendocardial viability ratio. We hypothesized that the presence of obstructive sleep apnea in severe obesity, even in the absence of an antecedent history of cardiovascular disease, would affect measurements derived from pulse wave analysis. Seventy-two severely obese adult subjects [obstructive sleep apnea 47 (body mass index 42 ± 7 kg m(-2) ), without obstructive sleep apnea (non-OSA) 25 (body mass index 40 ± 5 kg m(-2) )] were characterised using anthropometric, respiratory and cardio-metabolic parameters. Groups were similar in age, body mass index and gender. More subjects with obstructive sleep apnea had metabolic syndrome [obstructive sleep apnea 60%, without obstructive sleep apnea (non-OSA) 12%]. Those with obstructive sleep apnea had greater arterial stiffness, augmentation pressure and decreased subendocardial viability ratio (all P arterial pressures (P = 0.004) than patients without obstructive sleep apnea (non-OSA). Arterial stiffness correlated with mean arterial blood pressure (P = 0.003) and obstructive sleep apnea severity (apnea-hypopnea index; P arterial stiffness in multiple regression analysis, but components of the metabolic syndrome did not. Thus, patients with obstructive sleep apnea with severe obesity have increased arterial stiffness that may potentially influence cardiovascular risk independently of metabolic abnormalities. The presence of obstructive sleep apnea in severe obesity identifies a group at high cardiovascular risk; clinicians should ensure that risk factors are managed

  14. Uric acid promotes vascular stiffness, maladaptive inflammatory responses and proteinuria in western diet fed mice.

    Science.gov (United States)

    Aroor, Annayya R; Jia, Guanghong; Habibi, Javad; Sun, Zhe; Ramirez-Perez, Francisco I; Brady, Barron; Chen, Dongqing; Martinez-Lemus, Luis A; Manrique, Camila; Nistala, Ravi; Whaley-Connell, Adam T; Demarco, Vincent G; Meininger, Gerald A; Sowers, James R

    2017-09-01

    Aortic vascular stiffness has been implicated in the development of cardiovascular disease (CVD) and chronic kidney disease (CKD) in obese individuals. However, the mechanism promoting these adverse effects are unclear. In this context, promotion of obesity through consumption of a western diet (WD) high in fat and fructose leads to excess circulating uric acid. There is accumulating data implicating elevated uric acid in the promotion of CVD and CKD. Accordingly, we hypothesized that xanthine oxidase(XO) inhibition with allopurinol would prevent a rise in vascular stiffness and proteinuria in a translationally relevant model of WD-induced obesity. Four-week-old C57BL6/J male mice were fed a WD with excess fat (46%) and fructose (17.5%) with or without allopurinol (125mg/L in drinking water) for 16weeks. Aortic endothelial and extracellular matrix/vascular smooth muscle stiffness was evaluated by atomic force microscopy. Aortic XO activity, 3-nitrotyrosine (3-NT) and aortic endothelial sodium channel (EnNaC) expression were evaluated along with aortic expression of inflammatory markers. In the kidney, expression of toll like receptor 4 (TLR4) and fibronectin were assessed along with evaluation of proteinuria. XO inhibition significantly attenuated WD-induced increases in plasma uric acid, vascular XO activity and oxidative stress, in concert with reductions in proteinuria. Further, XO inhibition prevented WD-induced increases in aortic EnNaC expression and associated endothelial and subendothelial stiffness. XO inhibition also reduced vascular pro-inflammatory and maladaptive immune responses induced by consumption of a WD. XO inhibition also decreased WD-induced increases in renal TLR4 and fibronectin that associated proteinuria. Consumption of a WD leads to elevations in plasma uric acid, increased vascular XO activity, oxidative stress, vascular stiffness, and proteinuria all of which are attenuated with allopurinol administration. Copyright © 2017 Elsevier Inc

  15. New method to improve dynamic stiffness of electro-hydraulic servo systems

    Science.gov (United States)

    Bai, Yanhong; Quan, Long

    2013-09-01

    Most current researches working on improving stiffness focus on the application of control theories. But controller in closed-loop hydraulic control system takes effect only after the controlled position is deviated, so the control action is lagged. Thus dynamic performance against force disturbance and dynamic load stiffness can’t be improved evidently by advanced control algorithms. In this paper, the elementary principle of maintaining piston position unchanged under sudden external force load change by charging additional oil is analyzed. On this basis, the conception of raising dynamic stiffness of electro hydraulic position servo system by flow feedforward compensation is put forward. And a scheme using double servo valves to realize flow feedforward compensation is presented, in which another fast response servo valve is added to the regular electro hydraulic servo system and specially utilized to compensate the compressed oil volume caused by load impact in time. The two valves are arranged in parallel to control the cylinder jointly. Furthermore, the model of flow compensation is derived, by which the product of the amplitude and width of the valve’s pulse command signal can be calculated. And determination rules of the amplitude and width of pulse signal are concluded by analysis and simulations. Using the proposed scheme, simulations and experiments at different positions with different force changes are conducted. The simulation and experimental results show that the system dynamic performance against load force impact is largely improved with decreased maximal dynamic position deviation and shortened settling time. That is, system dynamic load stiffness is evidently raised. This paper proposes a new method which can effectively improve the dynamic stiffness of electro-hydraulic servo systems.

  16. Cross-linking in collagen by nonenzymatic glycation increases the matrix stiffness in rabbit achilles tendon.

    Science.gov (United States)

    Reddy, G Kesava

    2004-01-01

    Nonenzymatic glycation of connective tissue matrix proteins is a major contributor to the pathology of diabetes and aging. Previously the author and colleagues have shown that nonenzymatic glycation significantly enhances the matrix stability in the Achilles tendon (Reddy et al., 2002, Arch. Biochem. Biophys., 399, 174-180). The present study was designed to gain further insight into glycation-induced collagen cross-linking and its relationship to matrix stiffness in the rabbit Achilles tendon. The glycation process was initiated by incubating the Achilles tendons (n = 6) in phosphate-buffered saline containing ribose, whereas control tendons (n = 6) were incubated in phosphate-buffered saline without ribose. Eight weeks following glycation, the biomechanical attributes as well as the degree of collagen cross-linking were determined to examine the potential associations between matrix stiffness and molecular properties of collagen. Compared to nonglycated tendons, the glycated tendons showed increased maximum load, stress, strain, Young's modulus of elasticity, and toughness indicating that glycation increases the matrix stiffness in the tendons. Glycation of tendons resulted in a considerable decrease in soluble collagen content and a significant increase in insoluble collagen and pentosidine. Analysis of potential associations between the matrix stiffness and degree of collagen cross-linking showed that both insoluble collagen and pentosidine exhibited a significant positive correlation with the maximum load, stress, and strain, Young's modulus of elasticity, and toughness (r values ranging from.61 to.94) in the Achilles tendons. However, the soluble collagen content present in neutral salt buffer, acetate buffer, and acetate buffer containing pepsin showed an inverse relation with the various biomechanical attributes tested (r values ranging from.22 to.84) in the Achilles tendons. The results of the study demonstrate that glycation-induced collagen cross

  17. Assessment of liver stiffness in patients with HCV and mixed cryoglobulinemia undergoing rituximab treatment.

    Science.gov (United States)

    Stasi, Cristina; Triboli, Elisa; Arena, Umberto; Urraro, Teresa; Petrarca, Antonio; Gragnani, Laura; Laffi, Giacomo; Zignego, Anna Linda

    2014-01-24

    Mixed cryoglobulinemia (MC) is a HCV-related lymphoproliferative disorder generally associated with advanced liver disease. Liver stiffness has been significantly correlated with histopathological stage of fibrosis. Moreover, it was influenced by necroinflammatory activity. Rituximab (RTX) is a chimeric anti-CD20 monoclonal antibody inducing transient B lymphocytes depletion that was shown to be useful and safe in the majority of HCV MC patients, leading also to improvement of cirrhotic syndrome. Aim of this study was to evaluate the modifications of liver stiffness following RTX treatment in HCV-related MC patients. Fourteen consecutive patients (10 F, 4 M; mean age 60.43 ± 43) with HCV-related chronic hepatitis (n = 10) or cirrhosis (n = 4) and MC, eligible for RTX treatment, were prospectively enrolled. Intravenous injection of 1 g of RTX was performed at day 0 and at day 15. Assessment of stiffness was carried out by Fibroscan (Echosens, Paris-France) at baseline, 15 days after the first infusion, and at month 1, 3 and 6 after therapy. MC symptoms significantly improved during the study, especially during the first 3 months. Liver stiffness observed 3 months after treatment was significantly reduced when compared with pre-treatment values (p = 0.01). This difference disappeared after 6 months of follow-up. Cytofluorimetric analysis showed a decrease of CD19+ peripheral blood cells, with the nadir at month 3 after therapy and B cell compartment reconstitution after 6 months. This study, for the first time showed that RTX-treatment in HCV-related MC induces a reduction of liver stiffness that is strictly associated with the B-cell depletion.

  18. Lower skin temperature decreases maximal cycling performance.

    Science.gov (United States)

    Imai, Daiki; Okazaki, Kazunobu; Matsumura, Shinya; Suzuki, Takashi; Miyazawa, Taiki; Suzuki, Akina; Takeda, Ryosuke; Hamamoto, Takeshi; Zako, Tetsuo; Kawabata, Takashi; Miyagawa, Toshiaki

    2011-12-01

    It is known that external cooling of body regions involved in exercise, prior to exercise, decreases anaerobic performance. However, there have been no studies reporting the effects of whole body skin surface cooling before exercise on maximal anaerobic capacity. In order to clarify the effects, we compared power output during the Wingate anaerobic test between preconditioning by exposure to temperature 10 degrees C and 25 degrees C. Eight healthy males carried out the Wingate test for 30 seconds, after pre-conditioning for 60 minutes using a perfusion suit with water at a temperature of 10 degrees C or 25 degrees C. We evaluated the peak power (PP) and peak power slope (PS) of the power output. Mean skin temperature (T(sk)) at 60 minutes of pre-conditioning in the 10 degrees C trial was significantly lower than in the 25 degrees C trial (p < 0.05). PP and also PS were significantly lower in the 10 degrees C trial than in the 25 degrees C trial. Changes (Δ) in PP between the 10 degrees C trial and the 25 degrees C trial were strongly correlated with ΔT(sk) and Δ in thigh and leg skin temperature (ΔT(thigh) and ΔT(leg), respectively), whereas ΔPS was strongly correlated with ΔT(sk), but not with ΔT(thigh) and ΔT(leg). Whole body skin surface cooling prior to exercise restricts anaerobic capacity, especially in the initial phase of exercise.

  19. Energy metabolism during repeated sets of leg press exercise leading to failure or not

    DEFF Research Database (Denmark)

    Gorostiaga, Esteban M; Navarro-Amézqueta, Ion; Calbet, José A L

    2012-01-01

    This investigation examined the influence of the number of repetitions per set on power output and muscle metabolism during leg press exercise. Six trained men (age 34 ± 6 yr) randomly performed either 5 sets of 10 repetitions (10REP), or 10 sets of 5 repetitions (5REP) of bilateral leg press...... exercise, with the same initial load and rest intervals between sets. Muscle biopsies (vastus lateralis) were taken before the first set, and after the first and the final sets. Compared with 5REP, 10REP resulted in a markedly greater decrease (P...

  20. Interventions for leg cramps in pregnancy.

    Science.gov (United States)

    Zhou, Kunyan; West, Helen M; Zhang, Jing; Xu, Liangzhi; Li, Wenjuan

    2015-08-11

    Leg cramps are a common problem in pregnancy. Various interventions have been used to treat them, including drug, electrolyte and vitamin therapies, and non-drug therapies. To assess the effectiveness and safety of different interventions for treating leg cramps in pregnancy. We searched the Cochrane Pregnancy and Childbirth Group's Register (31 March 2015) and reference lists of retrieved studies. Randomised controlled trials (RCTs) of any intervention (drug, electrolyte, vitamin or non-drug therapies) for treatment of leg cramps in pregnancy compared with placebo, no treatment or other treatment. Quinine was excluded for its known adverse effects (teratogenicity). Cluster-RCTS were considered for inclusion. Quasi-RCTs and cross-over studies were excluded. Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We included six studies (390 women). Four trials compared oral magnesium with placebo/no treatment, two compared oral calcium with no treatment, one compared oral vitamin B versus no treatment, and one compared oral calcium with oral vitamin C. Two of the trials were well-conducted and reported, the other four had design limitations. The process of random allocation was sub-optimal in three studies, and blinding was not attempted in two. Outcomes were reported in different ways, precluding the use of meta-analysis and limiting the strength of our conclusions.The 'no treatment' group in one four-arm trial has been used as the comparison group for the composite outcome (intensity and frequency of leg cramps) in magnesium, calcium, and vitamin B versus no treatment. This gives it disproportionate weight in the overall analysis, thus interpretation of these results should be cautious. Oral magnesium versus placebo/no treatmentMagnesium (taken orally for two to four weeks) did not consistently reduce the frequency of leg cramps compared with placebo or no treatment. Outcomes that showed

  1. Stiffness nanotomography of human epithelial cancer cells

    Science.gov (United States)

    Staunton, Jack R.; Doss, Bryant L.; Gilbert, C. Michael; Kasas, Sandor; Ros, Robert

    2012-02-01

    The mechanical stiffness of individual cells is important in both cancer initiation and metastasis. We present atomic force microscopy (AFM) based nanoindentation experiments on various human mammary and esophagus cell lines covering the spectrum from normal immortalized cells to highly metastatic ones. The combination of an AFM with a confocal fluorescence lifetime imaging microscope (FLIM) in conjunction with the ability to move the sample and objective independently allow for precise alignment of AFM probe and laser focus with an accuracy down to a few nanometers. This enables us to correlate the mechanical properties with the point of indentation in the FLIM image. We are using force-volume measurements as well as force indentation curves on distinct points on the cells to compare the elastic moduli of the nuclei, nucleoli, and the cytoplasm, and how they vary within and between individual cells and cell lines. Further, a detailed analysis of the force-indentation curves allows study of the cells' mechanical properties at different indentation depths and to generate 3D elasticity maps.

  2. STIFFNESS MODIFICATION OF COTTON IN CHITOSAN TREATMENT

    Directory of Open Access Journals (Sweden)

    CAMPOS Juan

    2017-05-01

    Full Text Available Chitosan is a biopolymer obtained from chitin, and among their most important aspects highlights its applications in a lot of industrial sectors due to its intrinsic properties, especially in the textile sector. In the last years, chitosan is widely used in the cotton and wool finishing processes due to its bond between them and its properties as an antifungical and antimicrobial properties. In this paper three different molecular weight chitosan are used in the finishing process of cotton to evaluate its influence in the surface properties modification. In order to evaluate the effect of the treatment with chitosan, flexural stiffness test is performed in warp and weft direction, and then the total value is calculated. The cotton fabric is treated with 5 g/L of different types of chitosan in an impregnation bath. This study shows the extent of surface properties modification of the cotton provided by three types of chitosan treatment. The results show that all types of chitosan modify the cotton flexural rigidity properties but the one which modifies it in a relevant manner is chitosan originated from shrimps. Chitosan, textile, flexural stiffnes, chitin, cotton.

  3. Arterial stiffness and cognitive function in the elderly.

    Science.gov (United States)

    Zeki Al Hazzouri, Adina; Yaffe, Kristine

    2014-01-01

    Cognitive decline and dementia are a major cause of disability and mortality among older adults. Cross-sectional evidence from observational studies suggests that greater arterial stiffness is associated with worse cognitive performance. These associations have been observed on measures of global cognition and across multiple domains of cognition. Epidemiologic evidence on the association between arterial stiffness and rate of cognitive decline has been less definitive, and very few studies have investigated the risk of developing dementia. This review summarizes the current research on arterial stiffness and cognition, issues around measurement, and the effect that potential intervention might have on the course of cognitive aging. The evidence on pharmacological and non-pharmacological (exercise, nutrition, etc.) interventions in older adults with arterial stiffness is promising. Yet there are no studies or trials that directly evaluate how interventions of arterial stiffness reduce or prevent cognitive impairment and risk of developing dementia. More research is needed to elucidate the causal link between arterial stiffness and cognitive decline and dementia, and to identify whether potential interventions to prevent or reduce arterial stiffness may benefit cognitive health of the elderly.

  4. Martial arts training attenuates arterial stiffness in middle aged adults.

    Science.gov (United States)

    Douris, Peter C; Ingenito, Teresa; Piccirillo, Barbara; Herbst, Meredith; Petrizzo, John; Cherian, Vincen; McCutchan, Christopher; Burke, Caitlin; Stamatinos, George; Jung, Min-Kyung

    2013-09-01

    Arterial stiffness increases with age and is related to an increased risk of coronary artery disease. Poor trunk flexibility has been shown to be associated with arterial stiffness in middle-aged subjects. The purpose of our research study was to measure arterial stiffness and flexibility in healthy middle-aged martial artists compared to age and gender matched healthy sedentary controls. Ten martial artists (54.0 ± 2.0 years), who practice Soo Bahk Do (SBD), a Korean martial art, and ten sedentary subjects (54.7 ± 1.8 years) for a total of twenty subjects took part in this cross-sectional study. Arterial stiffness was assessed in all subjects using pulse wave velocity (PWV), a recognized index of arterial stiffness. Flexibility of the trunk and hamstring were also measured. The independent variables were the martial artists and matched sedentary controls. The dependent variables were PWV and flexibility. There were significant differences, between the SBD practitioners and sedentary controls, in PWV (P = 0.004), in trunk flexibility (P= 0.002), and in hamstring length (P= 0.003). The middle-aged martial artists were more flexible in their trunk and hamstrings and had less arterial stiffness compared to the healthy sedentary controls. The flexibility component of martial art training or flexibility exercises in general may be considered as a possible intervention to reduce the effects of aging on arterial stiffness.

  5. The role of tissue renin angiotensin aldosterone system in the development of endothelial dysfunction and arterial stiffness

    Directory of Open Access Journals (Sweden)

    Annayya R Aroor

    2013-10-01

    Full Text Available Epidemiological studies support the notion that arterial stiffness is an independent predictor of adverse cardiovascular events contributing significantly to systolic hypertension, impaired ventricular-arterial coupling and diastolic dysfunction, impairment in myocardial oxygen supply and demand, and progression of kidney disease. Although arterial stiffness is associated with aging, it is accelerated in the presence of obesity and diabetes. The prevalence of arterial stiffness parallels the increase of obesity that is occurring in epidemic proportions and is partly driven by a sedentary life style and consumption of a high fructose, high salt and high fat western diet. Although the underlying mechanisms and mediators of arterial stiffness are not well understood, accumulating evidence supports the role of insulin resistance and endothelial dysfunction. The local tissue renin angiotensin aldosterone system (RAAS in the vascular tissue and immune cells and perivascular adipose tissue is recognized as an important element involved in endothelial dysfunction which contributes significantly to arterial stiffness. Activation of vascular RAAS is seen in humans and animal models of obesity and diabetes, and associated with enhanced oxidative stress and inflammation in the vascular tissue. The cross talk between angiotensin and aldosterone underscores the importance of mineralocorticoid receptors in modulation of insulin resistance, decreased bioavailability of nitric oxide, endothelial dysfunction and arterial stiffness. In addition, both innate and adaptive immunity are involved in this local tissue activation of RAAS. In this review we will attempt to present a unifying mechanism of how environmental and immunological factors are involved in this local tissue RAAS activation, and the role of this process in the development of endothelial dysfunction and arterial stiffness and targeting tissue RAAS activation.

  6. Effects of non-uniform stiffness on the swimming performance of a passively-flexing, fish-like foil model.

    Science.gov (United States)

    Lucas, Kelsey N; Thornycroft, Patrick J M; Gemmell, Brad J; Colin, Sean P; Costello, John H; Lauder, George V

    2015-10-08

    Simple mechanical models emulating fish have been used recently to enable targeted study of individual factors contributing to swimming locomotion without the confounding complexity of the whole fish body. Yet, unlike these uniform models, the fish body is notable for its non-uniform material properties. In particular, flexural stiffness decreases along the fish's anterior-posterior axis. To identify the role of non-uniform bending stiffness during fish-like propulsion, we studied four foil model configurations made by adhering layers of plastic sheets to produce discrete regions of high (5.5 × 10(-5) Nm(2)) and low (1.9 × 10(-5) Nm(2)) flexural stiffness of biologically-relevant magnitudes. This resulted in two uniform control foils and two foils with anterior regions of high stiffness and posterior regions of low stiffness. With a mechanical flapping foil controller, we measured forces and torques in three directions and quantified swimming performance under both heaving (no pitch) and constant 0° angle of attack programs. Foils self-propelled at Reynolds number 21 000-115 000 and Strouhal number ∼0.20-0.25, values characteristic of fish locomotion. Although previous models have emphasized uniform distributions and heaving motions, the combination of non-uniform stiffness distributions and 0° angle of attack pitching program was better able to reproduce the kinematics of freely-swimming fish. This combination was likewise crucial in maximizing swimming performance and resulted in high self-propelled speeds at low costs of transport and large thrust coefficients at relatively high efficiency. Because these metrics were not all maximized together, selection of the 'best' stiffness distribution will depend on actuation constraints and performance goals. These improved models enable more detailed, accurate analyses of fish-like swimming.

  7. Flexibility of feeding movements in pigs: effects of changes in food toughness and stiffness on the timing of jaw movements.

    Science.gov (United States)

    Montuelle, Stéphane J; Olson, Rachel; Curtis, Hannah; Sidote, JoAnna; Williams, Susan H

    2018-01-29

    In mammals, chewing movements can be modified, or flexible, in response to changes in food properties. Variability between and within food in the temporal characteristics of chewing movements can impact chewing frequency and rhythmicity, which in turn may affect food breakdown, energy expenditure and tooth wear. Here, we compared total chewing cycle duration and intra-cycle phase durations in pigs chewing on three foods varying in toughness and stiffness: apples (low toughness, low stiffness), carrots (high toughness, low stiffness), and almonds (high toughness, high stiffness). We also determined whether within-food variability in timing parameters is modified in response to changes in food properties. X-ray Reconstruction Of Moving Morphology (XROMM) demonstrates that the timing of jaw movements are flexible in response to changes in food properties. Within each food, pigs also exhibited flexibility in their ability to vary cycle parameters. The timing of jaw movements during processing of high-toughness foods is more variable, potentially decreasing chewing rhythmicity. In contrast, low-toughness foods result in jaw movements that are more stereotyped in their timing parameters. In addition, the duration of tooth-food-tooth contact is more variable during the processing of low-stiffness foods compared with tough or stiff foods. Increased toughness is suggested to alter the timing of the movements impacting food fracture whereas increased stiffness may require a more cautious control of jaw movements. This study emphasizes that flexibility in biological movements in response to changes in conditions may not only be observed in timing but also in the variability of their timing within each condition. © 2018. Published by The Company of Biologists Ltd.

  8. Spin-wave stiffness in the Dzyaloshinskii-Moriya helimagnets Mn1 -xFexSi

    Science.gov (United States)

    Grigoriev, S. V.; Altynbaev, E. V.; Siegfried, S.-A.; Pschenichnyi, K. A.; Menzel, D.; Heinemann, A.; Chaboussant, G.

    2018-01-01

    The small-angle neutron scattering is used to measure the spin-wave stiffness in the field-polarized state of the Dzyaloshinskii-Moriya helimagnets Mn1 -xFexSi with x =0.03 , 0.06, 0.09, and 0.10. The Mn1 -xFexSi compounds are helically ordered below Tc and show a helical fluctuation regime above Tc in a wide range up to TDM. The critical temperatures Tc and TDM decrease with x and tend to 0 at x =0.11 and 0.17, respectively. We have found that the spin-wave stiffness A change weakly with temperature for each individual Fe-doped compound. On the other hand, the spin-wave stiffness A decreases with x duplicating the TDM dependence on x , rather than Tc(x ) . These findings classify the thermal phase transition in all Mn1 -xFexSi compounds as an abrupt change in the spin state caused, most probably, by the features of an electronic band structure. Moreover, the criticality in these compounds is not related to the value of the ferromagnetic interaction but demonstrates the remarkable role of the Dzyaloshinskii-Moriya interaction as a factor destabilizing the magnetic order.

  9. Effect of particle stiffness on contact dynamics and rheology in a dense granular flow

    Science.gov (United States)

    Bharathraj, S.; Kumaran, V.

    2018-01-01

    Dense granular flows have been well described by the Bagnold rheology, even when the particles are in the multibody contact regime and the coordination number is greater than 1. This is surprising, because the Bagnold law should be applicable only in the instantaneous collision regime, where the time between collisions is much larger than the period of a collision. Here, the effect of particle stiffness on rheology is examined. It is found that there is a rheological threshold between a particle stiffness of 104-105 for the linear contact model and 105-106 for the Hertzian contact model above which Bagnold rheology (stress proportional to square of the strain rate) is valid and below which there is a power-law rheology, where all components of the stress and the granular temperature are proportional to a power of the strain rate that is less then 2. The system is in the multibody contact regime at the rheological threshold. However, the contact energy per particle is less than the kinetic energy per particle above the rheological threshold, and it becomes larger than the kinetic energy per particle below the rheological threshold. The distribution functions for the interparticle forces and contact energies are also analyzed. The distribution functions are invariant with height, but they do depend on the contact model. The contact energy distribution functions are well fitted by Gamma distributions. There is a transition in the shape of the distribution function as the particle stiffness is decreased from 107 to 106 for the linear model and 108 to 107 for the Hertzian model, when the contact number exceeds 1. Thus, the transition in the distribution function correlates to the contact regime threshold from the binary to multibody contact regime, and is clearly different from the rheological threshold. An order-disorder transition has recently been reported in dense granular flows. The Bagnold rheology applies for both the ordered and disordered states, even though

  10. Longitudinal assessment of liver stiffness in patients undergoing antiviral treatment for hepatitis C.

    Science.gov (United States)

    Stasi, Cristina; Arena, Umberto; Zignego, Anna Linda; Corti, Giampaolo; Monti, Monica; Triboli, Elisa; Pellegrini, Elena; Renzo, Sara; Leoncini, Luisa; Marra, Fabio; Laffi, Giacomo; Milani, Stefano; Pinzani, Massimo

    2013-10-01

    Liver stiffness has been suggested as a parameter of fibrosis progression/regression in hepatitis C virus (HCV) patients. To evaluate stiffness before and after peginterferon-ribavirin treatment. Stiffness was prospectively measured in 74 HCV patients, 32 genotypes 1/4 (43.25%) and 42 genotypes 2/3 (56.75%), before, at end of treatment, and after 3 years of follow-up (49 patients). On the same study day, 21 patients underwent liver biopsy. In 55 patients with sustained virological response (74.32%), liver stiffness decreased significantly at end of therapy (6.8±4.9kPa) vs. baseline (9.5±6.9kPa, p=0.04). The decrease vs. baseline was maintained in 30 sustained virological response patients after 3 years follow-up (6.8±4.6kPa vs. 10.8±8.5kPa, p=0.0141). No difference was found at end of treatment vs. baseline (10.1±4.7kPa vs. 9.7±4.2kPa, p=0.825) and after 3 years of follow-up vs. baseline (10.2±3.4kPa vs. 9.7±4.2kPa, p=0.765) in null responders. Similar results were found in relapsers at end of treatment vs. baseline (13.7±7.7kPa vs. 15.2±8.2kPa, p=0.74), and after 3 years of follow-up vs. baseline (16.9±10.0kPa vs. 15.2±8.2kPa, p=0.734). Pre-treatment stiffness >12kPa was significantly associated with no SVR (p<0.025), RR=2.44 (95%C.I. 1.17-5.07). Liver stiffness may be useful to assess long-term antiviral treatment response. Copyright © 2013 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

  11. Leg power among malaysian netball players | Geok | African Journal ...

    African Journals Online (AJOL)

    The purpose of the study was to compare the leg power among Malaysian national netball players according to their age and playing position. The Vertical Jump Test was chosen to measure the leg power by using “Digital Indication Jump Meter” device. The results of the Vertical Jump Test were used to compare the leg ...

  12. Protection against high intravascular pressure in giraffe legs

    DEFF Research Database (Denmark)

    Petersen, Karin K; Hørlyck, Arne; Østergaard, Kristine Hovkjær

    2013-01-01

    The high blood pressure in giraffe leg arteries renders giraffes vulnerable to edema. We investigated in 11 giraffes whether large and small arteries in the legs and the tight fascia protect leg capillaries. Ultrasound imaging of foreleg arteries in anesthetized giraffes and ex vivo examination...

  13. Leg length, sitting height, and body proportions references for achondroplasia: New tools for monitoring growth.

    Science.gov (United States)

    Del Pino, Mariana; Ramos Mejía, Rosario; Fano, Virginia

    2018-04-01

    Achondroplasia is the most common form of inherited disproportionate short stature. We report leg length, sitting height, and body proportion curves for achondroplasia. Seven centile format of sitting height, leg length, sitting height/leg length ratio, sitting height/height ratio, and head circumference/height ratio were estimated by the LMS method. The Q-test was applied to assess the goodness of fit. For comparison, centiles of sitting height and leg length were graphed using Argentine national growth references for achondroplasia and non-achondroplasia populations. The sample consisted of 342 children with achondroplasia (171 males, 171 females) aged 0-18 years. The median (interquartile range) number of measurements per child was 6 (3, 12) for sitting height and 8 (3, 13) for head circumference. Median leg length increased from 14 cm at age 1 week to 44 and 40 cm (males and females, respectively) in achondroplasia adolescents which is 3.5 cm shorter than non-achondroplasia children at age 1 week and, 38 cm shorter at adolescence. Median sitting height increased from 34 cm at birth to 86 and 81 in adolescents' boys and girls respectively, only 5 cm shorter than non-achondroplasia children. Sitting height/leg length decreased from 2.61 at birth to approximately 1.90 at adolescent. Median head circumference/height ratio decreased from 0.79 at birth to 0.46 at 18 years in both sexes. Growth of lower limbs is affected early in life and becomes more noticeable throughout childhood. The disharmonic growth between the less affected trunk and the severely affected limbs determine body disproportion in achondroplasia. © 2018 Wiley Periodicals, Inc.

  14. Two pedigrees with restless legs syndrome in Brazil

    Directory of Open Access Journals (Sweden)

    A.M. Esteves

    2008-02-01

    Full Text Available Numerous studies have suggested a substantial genetic contribution in the etiology of the primary form of restless legs syndrome (RLS and periodic leg movements (PLM. We describe the symptoms, the sleep profiles and physiological parameters of two families in which several members present RLS/PLM. The proband of family 1 is a 70-year-old woman and the proband of family 2 is a 57-year-old woman; both have exhibited the symptoms since the age of 20 years. All patients in both families were diagnosed with RLS according to the criteria of the International RLS Study Group. Polysomnographic recordings were performed to quantify and to describe PLM during sleep. Sleep parameters showed decreased sleep efficiency, increased sleep latency in the arousal index and the presence of PLM in all subjects. One of the families showed an exact profile of dominant inheritance with anticipation of age at onset. In the other family, the founders were blood relatives and there was no affected member in the third generation suggesting a recessive mode of inheritance. RLS/PLM is a prevalent sleep disorder affecting about 5 to 15% of the population and one that substantially impairs healthy sleep patterns. Efforts to understand the underlying pathophysiology will contribute to improve the sleep and life quality of these patients.

  15. Alterations in Leg Extensor Muscle-Tendon Unit Biomechanical Properties With Ageing and Mechanical Loading

    Directory of Open Access Journals (Sweden)

    Christopher McCrum

    2018-02-01

    Full Text Available Tendons transfer forces produced by muscle to the skeletal system and can therefore have a large influence on movement effectiveness and safety. Tendons are mechanosensitive, meaning that they adapt their material, morphological and hence their mechanical properties in response to mechanical loading. Therefore, unloading due to immobilization or inactivity could lead to changes in tendon mechanical properties. Additionally, ageing may influence tendon biomechanical properties directly, as a result of biological changes in the tendon, and indirectly, due to reduced muscle strength and physical activity. This review aimed to examine age-related differences in human leg extensor (triceps surae and quadriceps femoris muscle-tendon unit biomechanical properties. Additionally, this review aimed to assess if, and to what extent mechanical loading interventions could counteract these changes in older adults. There appear to be consistent reductions in human triceps surae and quadriceps femoris muscle strength, accompanied by similar reductions in tendon stiffness and elastic modulus with ageing, whereas the effect on tendon cross sectional area is unclear. Therefore, the observed age-related changes in tendon stiffness are predominantly due to changes in tendon material rather than size with age. However, human tendons appear to retain their mechanosensitivity with age, as intervention studies report alterations in tendon biomechanical properties in older adults of similar magnitudes to younger adults over 12–14 weeks of training. Interventions should implement tendon strains corresponding to high mechanical loads (i.e., 80–90% MVC with repetitive loading for up to 3–4 months to successfully counteract age-related changes in leg extensor muscle-tendon unit biomechanical properties.

  16. Drop casting of stiffness gradients for chip integration into stretchable substrates

    International Nuclear Information System (INIS)

    Naserifar, Naser; LeDuc, Philip R; Fedder, Gary K

    2017-01-01

    Stretchable electronics have demonstrated promise within unobtrusive wearable systems in areas such as health monitoring and medical therapy. One significant question is whether it is more advantageous to develop holistic stretchable electronics or to integrate mature CMOS into stretchable electronic substrates where the CMOS process is separated from the mechanical processing steps. A major limitation with integrating CMOS is the dissimilar interface between the soft stretchable and hard CMOS materials. To address this, we developed an approach to pattern an elastomeric polymer layer with spatially varying mechanical properties around CMOS electronics to create a controllable material stiffness gradient. Our experimental approach reveals that modifying the interfaces can increase the strain failure threshold up to 30% and subsequently decreases delamination. The stiffness gradient in the polymer layer provides a safe region for electronic chips to function under a substrate tensile strain up to 150%. These results will have impacts in diverse applications including skin sensors and wearable health monitoring systems. (paper)

  17. Systemic Mastocytosis: A Rare Case of Increased Liver Stiffness

    Directory of Open Access Journals (Sweden)

    Stefanie Adolf

    2012-01-01

    Full Text Available Assessment of liver stiffness (LS by transient elastography (Fibroscan has significantly improved the noninvasive diagnosis of liver fibrosis. We here report on a 55-year-old patient with drastically increased LS due to previously unknown systemic mastocytosis. The patient initially presented with increased weight loss, nocturnal pruritus, increased transaminases, bilirubinemia, and thrombocytopenia. Abdominal ultrasound showed ascites, hepatomegaly, and splenomegaly. In addition, LS was 75 kPa (IQR 0 kPa clearly exceeding the cut-off value for F4 cirrhosis of 12.5 kPa. However, histological analysis of the liver specimen indicated liver involvement by systemic mastocytosis and excluded liver cirrhosis. An additional CT scan detected disseminated bone lesions. After three months of treatment with Midostaurin, LS slightly decreased down to 31.9 kPa (IQR 8.3 kPa. This case illustrates that diffused sinusoidal neoplastic infiltrates are a pitfall in the non-invasive diagnosis of liver cirrhosis. In conclusion, refined clinical algorithms for increased LS should also include mastocytosis in addition to inflammation, congestion, and biliary obstruction.

  18. Stiff self-interacting strings at high temperature QCD

    Directory of Open Access Journals (Sweden)

    S Bakry A.

    2018-01-01

    Full Text Available We investigate the implications of Nambu-Goto (NG, Lüscher Weisz (LW and Polyakov-Kleinert (PK effective string actions for the Casimir energy and the width of the quantum delocalization of the string in 4-dim pure SU(3 Yang-Mills lattice gauge theory. At a temperature closer to the critical point T/Tc=0.9, we found that the next to leading-order (NLO contributions from the expansion of the NG string in addition to the boundary terms in LW action to decrease the deviations from the lattice data in the intermediate distance scales for both the quark-antiquark QQ̅ potential and broadening of the color tube compared to the free string approximation. We conjecture possible stiffness of the QCD string through studying the effects of extrinsic curvature term in PK action and find a good fitting behavior for the lattice Monte-Carlo data at both long and intermediate quark separations regions.

  19. Hormones and arterial stiffness in patients with chronic kidney disease.

    Science.gov (United States)

    Gungor, Ozkan; Kircelli, Fatih; Voroneanu, Luminita; Covic, Adrian; Ok, Ercan

    2013-01-01

    Cardiovascular disease constitutes the major cause of mortality in patients with chronic kidney disease. Arterial stiffness is an important contributor to the occurrence and progression of cardiovascular disease. Various risk factors, including altered hormone levels, have been suggested to be associated with arterial stiffness. Based on the background that chronic kidney disease predisposes individuals to a wide range of hormonal changes, we herein review the available data on the association between arterial stiffness and hormones in patients with chronic kidney disease and summarize the data for the general population.

  20. Immediate effects of the trunk stabilizing exercise on static balance parameters in double-leg and one-leg stances

    OpenAIRE

    Kim, Jwa-jun; Park, Se-yeon

    2016-01-01

    [Purpose] The purpose of this study was to evaluate the immediate effect of stabilizing exercise using the PNF technique on standing balance in one-leg and double-leg stances. [Subjects and Methods] The present study recruited 34 healthy participants from a local university. The Participants performed four balance tests (double-leg stance with and without vision, one-leg stance with and without vision), before and after exercise. The exercise consisted of exercises performed using PNF techniq...

  1. Influence of stress state stiffness on wear resistance of materials under conditions of hydro- and impact abrasive wear

    International Nuclear Information System (INIS)

    Pogodaev, L.I.; Tsvetkov, Yu.N.; Khomyakova, N.F.

    1997-01-01

    Aimed to develop a universal criterion of wear resistance a wide range of steels and nonferrous alloys was tested and testing results were analyzed. The specimens were tested for hydro-abrasive and impact-abrasive wear. It is shown that wear resistance is dependent on the parameter which characterizes the stiffness of stressed state for thin wearing layers. The critical density of strain energy determined with regard to the stiffness of stressed state of surface layers is concluded to be an universal criterion of wear resistance. it is revealed that the stiffness of surface stressed state decreases with a hardness increase and with transition from tension to compression or shear. This phenomenon is considered as the protection of surface layers against catastrophic failure. The data on mechanical properties are presented for a great quantity of cast materials (stainless, chromium and manganese steels, aluminium and copper alloys)

  2. Loss of dystrophin is associated with increased myocardial stiffness in a model of left ventricular hypertrophy.

    Science.gov (United States)

    Donato, Martín; Buchholz, Bruno; Morales, Celina; Valdez, Laura; Zaobornyj, Tamara; Baratta, Sergio; Paez, Diamela T; Matoso, Mirian; Vaccarino, Guillermo; Chejtman, Demian; Agüero, Oscar; Telayna, Juan; Navia, José; Hita, Alejandro; Boveris, Alberto; Gelpi, Ricardo J

    2017-08-01

    Transition from compensated to decompensated left ventricular hypertrophy (LVH) is accompanied by functional and structural changes. Here, the aim was to evaluate dystrophin expression in murine models and human subjects with LVH by transverse aortic constriction (TAC) and aortic stenosis (AS), respectively. We determined whether doxycycline (Doxy) prevented dystrophin expression and myocardial stiffness in mice. Additionally, ventricular function recovery was evaluated in patients 1 year after surgery. Mice were subjected to TAC and monitored for 3 weeks. A second group received Doxy treatment after TAC. Patients with AS were stratified by normal left ventricular end-diastolic wall stress (LVEDWS) and high LVEDWS, and groups were compared. In mice, LVH decreased inotropism and increased myocardial stiffness associated with a dystrophin breakdown and a decreased mitochondrial O 2 uptake (MitoMVO 2 ). These alterations were attenuated by Doxy. Patients with high LVEDWS showed similar results to those observed in mice. A correlation between dystrophin and myocardial stiffness was observed in both mice and humans. Systolic function at 1 year post-surgery was only recovered in the normal-LVEDWS group. In summary, mice and humans present diastolic dysfunction associated with dystrophin degradation. The recovery of ventricular function was observed only in patients with normal LVEDWS and without dystrophin degradation. In mice, Doxy improved MitoMVO 2 . Based on our results it is concluded that the LVH with high LVEDWS is associated to a degradation of dystrophin and increase of myocardial stiffness. At least in a murine model these alterations were attenuated after the administration of a matrix metalloprotease inhibitor.

  3. BUILDING A BETTER GLUTEAL BRIDGE: ELECTROMYOGRAPHIC ANALYSIS OF HIP MUSCLE ACTIVITY DURING MODIFIED SINGLE-LEG BRIDGES

    Science.gov (United States)

    Edwards, Michael; Haverkamp, Ryan; Martin, Lani; Porter, Kambry; Thach, Kailey; Sack, Richard J.; Hakansson, Nils A.

    2017-01-01

    Background Gluteal strength plays a role in injury prevention, normal gait patterns, eliminating pain, and enhancing athletic performance. Research shows high gluteal muscle activity during a single-leg bridge compared to other gluteal strengthening exercises; however, prior studies have primarily measured muscle activity with the active lower extremity starting in 90 ° of knee flexion with an extended contralateral knee. This standard position has caused reports of hamstring cramping, which may impede optimal gluteal strengthening. Hypothesis/Purpose The purpose of this study was to determine which modified position for the single-leg bridge is best for preferentially activating the gluteus maximus and medius. Study Design Cross-Sectional Methods Twenty-eight healthy males and females aged 18-30 years were tested in five different, randomized single-leg bridge positions. Electromyography (EMG) electrodes were placed on subjects’ gluteus maximus, gluteus medius, rectus femoris, and biceps femoris of their bridge leg (i.e., dominant or kicking leg), as well as the rectus femoris of their contralateral leg. Subjects performed a maximal voluntary isometric contraction (MVIC) for each tested muscle prior to performing five different bridge positions in randomized order. All bridge EMG data were normalized to the corresponding muscle MVIC data. Results A modified bridge position with the knee of the bridge leg flexed to 135 ° versus the traditional 90 ° of knee flexion demonstrated preferential activation of the gluteus maximus and gluteus medius compared to the traditional single-leg bridge. Hamstring activation significantly decreased (p gluteus maximus and medius, respectively). Conclusion Modifying the traditional single-leg bridge by flexing the active knee to 135 ° instead of 90 ° minimizes hamstring activity while maintaining high levels of gluteal activation, effectively building a bridge better suited for preferential gluteal activation

  4. Fluorescence spectroscopy for non-invasive measurement of mechanical stiffness after photo-crosslinking of rabbit cornea

    Science.gov (United States)

    Williams, Maura; Lewis, William; Ortega-Martinez, Antonio; Franco, Walfre

    2017-02-01

    Background and Objectives: Keratoconus is a disease characterized by progressive steepening and thinning of the cornea, altering visual acuity and sometimes potentiating the need for corneal transplant if the disease progresses.1-3 Corneal crosslinking, a procedure that uses topical riboflavin and UV light to increase the stiffness of the cornea through the creation of collagen crosslinks was recently approved by the FDA for use in the U.S. The objective of the present study was to investigate whether endogenous collagen fluorescence changes following treatment can be correlated to alterations in the stiffness of the cornea, thereby guiding treatment parameters. Study Design and Results: 78 ex-vivo rabbit eyes divided into three groups: riboflavin solution plus UV irradiation, dextran solution plus UV irradiation, and riboflavin solution only. An additional group of eyes received no treatment. The epithelium was removed from each sample and topical riboflavin was applied. Eyes were irradiated with a 365 nm black ray UV lamp for various treatment times, ranging from half the clinical treatment time to three times the length. Mechanical testing was performed to determine the force/displacement relationship for the various treatment times. Fluorescence spectral changes following treatment corresponded with changes in stiffness. In particular, a decrease in the value of fluorescence intensity at 290/340 nm excitation/emission wavelengths corresponded to an increase in corneal stiffness following treatment. It may be possible to use fluorescence spectral changes of endogenous corneal crosslinks to evaluate mechanical stiffness changes non-invasively.

  5. The Acute Effect of Local Vibration As a Recovery Modality from Exercise-Induced Increased Muscle Stiffness.

    Science.gov (United States)

    Pournot, Hervé; Tindel, Jérémy; Testa, Rodolphe; Mathevon, Laure; Lapole, Thomas

    2016-03-01

    Exercise involving eccentric muscle contractions is known to decrease range of motion and increase passive muscle stiffness. This study aimed at using ultrasound shear wave elastography to investigate acute changes in biceps brachii passive stiffness following intense barbell curl exercise involving both concentric and eccentric contractions. The effect of local vibration (LV) as a recovery modality from exercise-induced increased stiffness was further investigated. Eleven subjects performed 4 bouts of 10 bilateral barbell curl movements at 70% of the one-rep maximal flexion force. An arm-to-arm comparison model was then used with one arm randomly assigned to the passive recovery condition and the other arm assigned to the LV recovery condition (10 min of 55-Hz vibration frequency and 0.9-mm amplitude). Biceps brachii shear elastic modulus measurements were performed prior to exercise (PRE), immediately after exercise (POST-EX) and 5 min after the recovery period (POST-REC). Biceps brachii shear elastic modulus was significantly increased at POST-EX (+53 ± 48%; p barbell curl exercise induce an immediate increased passive stiffness of the biceps brachii muscle, as evidenced by greater shear elastic modulus measured by supersonic shear imaging.The administration of a vibratory massage did not reduce this acute exercise-induced increased stiffness.

  6. Negative stiffness honeycombs as tunable elastic metamaterials

    Science.gov (United States)

    Goldsberry, Benjamin M.; Haberman, Michael R.

    2018-03-01

    Acoustic and elastic metamaterials are media with a subwavelength structure that behave as effective materials displaying atypical effective dynamic properties. These material systems are of interest because the design of their sub-wavelength structure allows for direct control of macroscopic wave dispersion. One major design limitation of most metamaterial structures is that the dynamic response cannot be altered once the microstructure is manufactured. However, the ability to modify wave propagation in the metamaterial with an external stimulus is highly desirable for numerous applications and therefore remains a significant challenge in elastic metamaterials research. In this work, a honeycomb structure composed of a doubly periodic array of curved beams, known as a negative stiffness honeycomb (NSH), is analyzed as a tunable elastic metamaterial. The nonlinear static elastic response that results from large deformations of the NSH unit cell leads to a large variation in linear elastic wave dispersion associated with infinitesimal motion superposed on the externally imposed pre-strain. A finite element model is utilized to model the static deformation and subsequent linear wave motion at the pre-strained state. Analysis of the slowness surface and group velocity demonstrates that the NSH exhibits significant tunability and a high degree of anisotropy which can be used to guide wave energy depending on static pre-strain levels. In addition, it is shown that partial band gaps exist where only longitudinal waves propagate. The NSH therefore behaves as a meta-fluid, or pentamode metamaterial, which may be of use for applications of transformation elastodynamics such as cloaking and gradient index lens devices.

  7. An extended steepness model for leg-size determination based on Dachsous/Fat trans-dimer system.

    Science.gov (United States)

    Yoshida, Hiroshi; Bando, Tetsuya; Mito, Taro; Ohuchi, Hideyo; Noji, Sumihare

    2014-03-11

    What determines organ size has been a long-standing biological question. Lawrence et al. (2008) proposed the steepness hypothesis suggesting that the protocadherin Dachsous/Fat (Ds/Ft) system may provide some measure of dimension to the cells in relation to the gradient. In this paper we extended the model as a means of interpreting experimental results in cricket leg regeneration. We assumed that (1) Ds/Ft trans-heterodimers or trans-homodimers are redistributed during cell division, and (2) growth would cease when a differential of the dimer across each cell decreases to a certain threshold. We applied our model to simulate the results obtained by leg regeneration experiments in a cricket model. The results were qualitatively consistent with the experimental data obtained for cricket legs by RNA interference methodology. Using our extended steepness model, we provided a molecular-based explanation for leg size determination even in intercalary regeneration and for organ size determination.

  8. Clinical quality indicators of venous leg ulcers

    DEFF Research Database (Denmark)

    Kjaer, Monica L; Mainz, Jan; Soernsen, Lars T

    2005-01-01

    and reliable evidence-based quality indicators of venous leg ulcer care. A Scandinavian multidisciplinary, cross-sectional panel of wound healing experts developed clinical quality indicators on the basis of scientific evidence from the literature and subsequent group nominal consensus of the panel......; an independent medical doctor tested the feasibility and reliability of these clinical indicators, assessing the quality of medical technical care on 100 consecutive venous leg ulcer patients. Main outcome measures were healing, recurrence, pain, venous disease diagnosis, differential diagnosis and treatment......%) were assessed for venous surgery. Distal arterial pressure was measured following initial examination in 33 of the patients (34%). All patients (100%) were prescribed compression therapy. Of the 98 patients, 11 (11%) had ulcers recur in 3 months and 72 (73%) healed in 12 months, which is in line...

  9. Lower Leg Anterior and Lateral Intracompartmental Pressure Changes Before and After Classic Versus Skate Nordic Rollerskiing.

    Science.gov (United States)

    Woods, Katherine M; Petron, David J; Shultz, Barry B; Hicks-Little, Charlie A

    2015-08-01

    Chronic exertional compartment syndrome (CECS) is a debilitating condition resulting in loss of function and a decrease in athletic performance. Cases of CECS are increasing among Nordic skiers; therefore, analysis of intracompartmental pressures (ICPs) before and after Nordic skiing is warranted. To determine if lower leg anterior and lateral ICPs and subjective lower leg pain levels increased after a 20-minute Nordic rollerskiing time trial and to examine if differences existed between postexercise ICPs for the 2 Nordic rollerskiing techniques, classic and skate. Crossover study. Outdoor paved loop. Seven healthy Division I Nordic skiers (3 men, 4 women; age = 22.71 ± 1.38 y, height = 175.36 ± 6.33 cm, mass = 70.71 ± 6.58 kg). Participants completed two 20-minute rollerskiing time trials using the classic and skate technique in random order. The time trials were completed 7 days apart. Anterior and lateral ICPs and lower leg pain scores were obtained at baseline and at minutes 1 and 5 after rollerskiing. Anterior and lateral ICPs (mm Hg) were measured using a Stryker Quic STIC handheld monitor. Subjective measures of lower leg pain were recorded using the 11-point Numeric Rating Scale. Increases in both anterior (P = .000) and lateral compartment (P = .002) ICPs were observed, regardless of rollerskiing technique used. Subjective lower leg pain increased after the classic technique for the men from baseline to 1 minute postexercise and after the skate technique for the women. Significant 3-way interactions (technique × time × sex) were observed for the anterior (P = .002) and lateral (P = .009) compartment ICPs and lower leg pain (P = .005). Postexercise anterior and lateral ICPs increased compared with preexercise ICPs after both classic and skate rollerskiing techniques. Lower leg pain is a primary symptom of CECS. The subjective lower leg pain 11-point Numeric Rating Scale results indicate that increases in lower leg ICPs sustained during Nordic

  10. Is preeclampsia associated with restless legs syndrome?

    OpenAIRE

    Ramirez, J O; Cabrera, S A S; Hidalgo, H; Cabrera, S G; Linnebank, M; Bassetti, C L; Kallweit, U

    2013-01-01

    OBJECTIVE: Restless legs syndrome (RLS) is a common neurologic disorder. Secondary RLS includes pregnancy and iron deficiency. Prevalence of RLS in pregnancy ranges from 11% to 27%. We aimed to assess the frequency and characteristics of RLS in pregnancy in a Peruvian population and to evaluate the possible pregnancy or delivery complications due to RLS. METHODS: We assessed 218 consecutive expectant mothers at the inpatient clinic of the Hospital San Bartolome in Lima, Peru. Assessment wa...

  11. Genetic aspects of restless legs syndrome

    OpenAIRE

    Dhawan, V; Ali, M; Chaudhuri, K R

    2006-01-01

    Restless legs syndrome (RLS), also known as Ekbom syndrome, is a common movement disorder with sensorimotor symptoms occurring during sleep and quiet wakefulness. The underlying cause for RLS is unknown but genetic influences play a strong part in the pathogenesis of RLS, particularly when the condition starts at a young age. This review explores the genetic basis of RLS and related phenotypic variations. Recently, three loci showing vulnerability to RLS have been described in French‐Canadian...

  12. Restless legs syndrome and pregnancy: A review

    OpenAIRE

    Srivanitchapoom, Prachaya; Pandey, Sanjay; Hallett, Mark

    2014-01-01

    Restless legs syndrome (RLS) is a common sensorimotor neurological disorder that is diagnosed according to the revised criteria of the International RLS Study Group (IRLSSG). The pathophysiology of RLS is still unknown and its prevalence is influenced by ethnicity, age, and gender. RLS is divided into two types by etiology: primary or idiopathic and secondary. Primary RLS is strongly influenced by a genetic component while secondary RLS is caused by other associated conditions such as end-sta...

  13. The relationship between pectoral fin ray stiffness and swimming behavior in Labridae: insights into design, performance and ecology.

    Science.gov (United States)

    Aiello, Brett R; Hardy, Adam R; Cherian, Chery; Olsen, Aaron M; Ahn, Sihyun E; Hale, Melina E; Westneat, Mark W

    2018-01-09

    The functional capabilities of flexible, propulsive appendages are directly influenced by their mechanical properties. The fins of fishes have undergone extraordinary evolutionary diversification in structure and function, which raises questions of how fin mechanics relate to swimming behavior. In the fish family Labridae, pectoral fin swimming behavior ranges from rowing to flapping. Rowers are more maneuverable than flappers, but flappers generate greater thrust at high speeds and achieve greater mechanical efficiency at all speeds. Interspecific differences in hydrodynamic capability are largely dependent on fin kinematics and deformation, and are expected to correlate with fin stiffness. Here we examine fin ray stiffness in two closely related species that employ divergent swimming behaviors, the flapping Gomphosus varius and the rowing Halichoeres bivittatus To determine the spatial distribution of flexural stiffness across the fin, we performed three-point bending tests at the center of the proximal, middle and distal regions of four equally spaced fin rays. Pectoral fin ray flexural stiffness ranged from 0.0001 to 1.5109 µN m 2 , and the proximal regions of G. varius fin rays were nearly an order of magnitude stiffer than those of H. bivittatus In both species, fin ray flexural stiffness decreased exponentially along the proximodistal span of fin rays, and flexural stiffness decreased along the fin chord from the leading to the trailing edge. Furthermore, the proportion of fin area occupied by fin rays was significantly greater in G. varius than in H. bivittatus , suggesting that the proportion of fin ray to fin area contributes to differences in fin mechanics. © 2018. Published by The Company of Biologists Ltd.

  14. Proprioceptive Actuation Design for Dynamic Legged locomotion

    Science.gov (United States)

    Kim, Sangbae; Wensing, Patrick; Biomimetic Robotics Lab Team

    Designing an actuator system for highly-dynamic legged locomotion exhibited by animals has been one of the grand challenges in robotics research. Conventional actuators designed for manufacturing applications have difficulty satisfying challenging requirements for high-speed locomotion, such as the need for high torque density and the ability to manage dynamic physical interactions. It is critical to introduce a new actuator design paradigm and provide guidelines for its incorporation in future mobile robots for research and industry. To this end, we suggest a paradigm called proprioceptive actuation, which enables highly- dynamic operation in legged machines. Proprioceptive actuation uses collocated force control at the joints to effectively control contact interactions at the feet under dynamic conditions. In the realm of legged machines, this paradigm provides a unique combination of high torque density, high-bandwidth force control, and the ability to mitigate impacts through backdrivability. Results show that the proposed design provides an impact mitigation factor that is comparable to other quadruped designs with series springs to handle impact. The paradigm is shown to enable the MIT Cheetah to manage the application of contact forces during dynamic bounding, with results given down to contact times of 85ms and peak forces over 450N. As a result, the MIT Cheetah achieves high-speed 3D running up to 13mph and jumping over an 18-inch high obstacle. The project is sponsored by DARPA M3 program.

  15. Sleep board review question: restless legs

    Directory of Open Access Journals (Sweden)

    Omobomi O

    2018-02-01

    Full Text Available No abstract available. Article truncated after 150 words. Ms. Jones (not her real name is a 63-year-old woman who states that she gets very fidgety when sitting in a theater, watching a movie or when flying long distances on a plane. She is unable to find words to describe the sensation but she states that moving her legs make them feel better. Lately, she has been getting this feeling almost every night. She reports no leg discomfort in the daytime. She denies muscle cramps her legs. She had some recent investigations done by her primary care physician because of complaints of fatigue. Which of the following will be helpful in the diagnosis and management in this patient? 1. An overnight polysomnogram showing apnea hypopnea index of 1.6 events per hour and no periodic limb movements (PLMs 2. Ferritin level of 18 ng/ml (normal range 20-200 ng/ml 3. Serum Bicarbonate of 29 mEq/L (normal range 23-29 mEq/L 4. Thyroid …

  16. Restless Legs Syndrome Among the Elderly

    Directory of Open Access Journals (Sweden)

    Pei-Hao Chen

    2009-12-01

    Full Text Available Restless legs syndrome is a sleep and movement disorder that affects 5–15% of the general population, with an increased prevalence among the elderly population. It not only affects quality of life but also increases risk of mortality among older adults. The diagnosis is based on clinical symptoms of the patient by four minimal essential criteria. Restless legs syndrome can be divided into primary or secondary causes. Examination should be performed to rule out potentially treatable illnesses, such as iron deficiency, renal failure or peripheral neuropathy, especially among elderly patients. The initial approach to restless legs syndrome should be nonpharmacologic management, such as good sleep hygiene, regular exercise, cognitive behavioral therapy and avoidance of certain aggravating drugs. An algorithm based on scientific evidence and expert opinion was developed for guidance of treatment. Combination or change of medication can be applied to resistant or difficult cases. Since elderly patients are prone to treatment-related side effects, the best strategy is to start medication cautiously and at the lowest recommended dosage.

  17. Molecular Cues Guiding Matrix Stiffness in Liver Fibrosis

    Directory of Open Access Journals (Sweden)

    Takaoki Saneyasu

    2016-01-01

    Full Text Available Tissue and matrix stiffness affect cell properties during morphogenesis, cell growth, differentiation, and migration and are altered in the tissue remodeling following injury and the pathological progression. However, detailed molecular mechanisms underlying alterations of stiffness in vivo are still poorly understood. Recent engineering technologies have developed powerful techniques to characterize the mechanical properties of cell and matrix at nanoscale levels. Extracellular matrix (ECM influences mechanical tension and activation of pathogenic signaling during the development of chronic fibrotic diseases. In this short review, we will focus on the present knowledge of the mechanisms of how ECM stiffness is regulated during the development of liver fibrosis and the molecules involved in ECM stiffness as a potential therapeutic target for liver fibrosis.

  18. Towards ultra-stiff materials: Surface effects on nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Dingjie; Xie, Yi Min; Huang, Xiaodong; Zhou, Shiwei, E-mail: shiwei.zhou@rmit.edu.au [Centre for Innovative Structures and Materials, School of Civil, Environmental and Chemical Engineering, RMIT University, GPO Box 2476, Melbourne 3001 (Australia); Li, Qing [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, New South Wales 2006 (Australia)

    2014-09-08

    The significant rise in the strength and stiffness of porous materials at nanoscale cannot be described by conventional scaling laws. This letter investigates the effective Young's modulus of such materials by taking into account surface effect in a microcellular architecture designed for an ultralight material whose stiffness is an order of magnitude higher than most porous materials. We find that by considering the surface effects the predicted stiffness using Euler-Bernoulli beam theory compares well to experimental data for spongelike nanoporous gold with random microstructures. Analytical results show that, of the two factors influencing the effective Young's modulus, the residual stress is more important than the surface stiffness.

  19. Operator-Based Preconditioning of Stiff Hyperbolic Systems

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Daniel R.; Samtaney, Ravi; Woodward, Carol S.

    2009-02-09

    We introduce an operator-based scheme for preconditioning stiff components encoun- tered in implicit methods for hyperbolic systems of partial differential equations posed on regular grids. The method is based on a directional splitting of the implicit operator, followed by a char- acteristic decomposition of the resulting directional parts. This approach allows for solution to any number of characteristic components, from the entire system to only the fastest, stiffness-inducing waves. We apply the preconditioning method to stiff hyperbolic systems arising in magnetohydro- dynamics and gas dynamics. We then present numerical results showing that this preconditioning scheme works well on problems where the underlying stiffness results from the interaction of fast transient waves with slowly-evolving dynamics, scales well to large problem sizes and numbers of processors, and allows for additional customization based on the specific problems under study.

  20. The measurement of plain weft-knitted fabric stiffness

    International Nuclear Information System (INIS)

    Mohamad, Ayhan Haji; Cassidy, Thomas; Brydon, Alan; Halley, Dave

    2012-01-01

    A new instrument and a test method are presented in this paper that can evaluate the stiffness of plain weft-knitted fabrics. The WIRA Instrumentation Tester can measure torsion data for various flexible fibre assemblies whilst they are being twisted. The torsional properties of two types of fabrics, namely nonwoven and knitted fabrics, were analyzed. Then, comparisons between bending rigidity and torsional rigidity have been conducted using FAST-2, Shirley, Heart Loop and the new WIRA method for the assessment of fabric stiffness. The results show high correlation between bending rigidity and torsional rigidity in assessment of nonwoven fabric stiffness; they also reveal that the WIRA tester and torsional rigidity are more suitable for characterizing the stiffness of plain weft-knitted fabrics than the other test methods. (paper)

  1. Comparative morphology of the prothoracic leg in heliconian butterflies: Tracing size allometry, podite fusions and losses in ontogeny and phylogeny.

    Science.gov (United States)

    Moreira, Gilson R P; Silva, Denis S; Gonçalves, Gislene L

    2017-07-01

    Prothoracic legs of heliconian butterflies (Nymphalidae, Heliconiinae, Heliconiini) are reduced in size compared to mesothoracic and metathoracic legs. They have no apparent function in males, but are used by females for drumming on host plants, a behavior related to oviposition site selection. Here, taking into account all recognized lineages of heliconian butterflies, we described their tarsi using optical and scanning electron microscopy and searched for podite fusions and losses, and analyzed allometry at the static, ontogenetic and phylogenetic levels. Female tarsi were similar, club-shaped, showing from four to five tarsomeres, each bearing sensilla chaetica and trichodea. Male tarsi were cylindrical, formed from five (early diverging lineages) to one (descendant lineages) either partially or totally fused tarsomeres, all deprived of sensilla. Pretarsi were reduced in both sexes, in some species being either vestigial or absent. Tarsal lengths were smaller for males in almost all species. An abrupt decrease in size was detected for the prothoracic legs during molting to the last larval instar at both histological and morphometric levels. In both sexes, most allometric coefficients found at the population level for the prothoracic legs were negative compared to the mesothoracic leg and also to wings. Prothoracic tarsi decreased proportionally in size over evolutionary time; the largest and smallest values being found for nodes of the oldest and youngest lineages, respectively. Our results demonstrate that evolution of the prothoracic leg in heliconian butterflies has been based on losses and fusions of podites, in association with negative size allometry at static, ontogenetic and phylogenetic levels. These processes have been more pronounced in males. Our study provided further support to the hypothesis that evolution of these leg structures is driven by females, by changing their use from walking to drumming during oviposition site selection. In males the

  2. Design and Evaluation of the AIRGAIT Exoskeleton: Leg Orthosis Control for Assistive Gait Rehabilitation

    Directory of Open Access Journals (Sweden)

    Mohd Azuwan Mat Dzahir

    2013-01-01

    Full Text Available This paper introduces the body weight support gait training system known as the AIRGAIT exoskeleton and delves into the design and evaluation of its leg orthosis control algorithm. The implementation of the mono- and biarticular pneumatic muscle actuators (PMAs as the actuation system was initiated to generate more power and precisely control the leg orthosis. This research proposes a simple paradigm for controlling the mono- and bi-articular actuator movements cocontractively by introducing a cocontraction model. Three tests were performed. The first test involved control of the orthosis with monoarticular actuators alone without a subject (WO/S; the second involved control of the orthosis with mono- and bi-articular actuators tested WO/S; and the third test involved control of the orthosis with mono- and bi-articular actuators tested with a subject (W/S. Full body weight support (BWS was implemented in this study during the test W/S as the load supported by the orthosis was at its maximum capacity. This assessment will optimize the control system strategy so that the system operates to its full capacity. The results revealed that the proposed control strategy was able to co-contractively actuate the mono- and bi-articular actuators simultaneously and increase stiffness at both hip and knee joints.

  3. Arterial Stiffness and Functional Outcome in Acute Ischemic Stroke

    OpenAIRE

    Lee, Yeong-Bae; Park, Joo-Hwan; Kim, Eunja; Kang, Chang-Ki; Park, Hyeon-Mi

    2014-01-01

    Objective Arterial stiffness is a common change associated with aging and can be evaluated by measuring pulse wave velocity (PWV) between sites in the arterial tree, with the stiffer artery having the higher PWV. Arterial stiffness is associated with the risk of stroke in the general population and of fatal stroke in hypertensive patients. This study is to clarify whether PWV value predicts functional outcome of acute ischemic stroke. Methods One hundred patients were enrolled with a diagnosi...

  4. Relationship between increased carotid artery stiffness and idiopathic subjective tinnitus.

    Science.gov (United States)

    Bayraktar, C; Taşolar, S

    2017-05-01

    Tinnitus is defined as perception of sound with no external stimulus, and can separate into pulsatile and non-pulsatile types. Arterial stiffness is a parameter that can predict the cardiovascular event and associated with incidence of stroke. It has been shown that increased arterial stiffness may lead to microvascular damage in brain. Our aim was to assess the arterial stiffness of the carotid system in the development and severity of idiopathic subjective tinnitus. Forty subjective tinnitus patients and 40 age- and sex-matched controls were enrolled in the study. The parameters obtained from the participants included pure tone hearing (dB), serum lipid profile (mg/dl), fasting glucose (mg/dl), blood pressure (mmHg), and body mass index (BMI, kg/m 2 ). The common carotid artery (CCA) stiffness index, Young's elastic modulus (YEM), common carotid intima-media thickness (CIMT), peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), pulsatility index (PI), vessel diameter, mean velocity (MV), and volume flow (VF) were measured in both the right and left common carotid arteries in both groups. The CCA stiffness index, YEM measurements, right CIMT, and left PI were found to be significantly higher in the patients than those in the control group (p tinnitus and the patient characteristics, there was a significant positive correlation with the CCA stiffness index, YEM measurements, left CIMT, and neutrophil-to-lymphocyte ratio (NLR). However, only the right and left CCA stiffness parameters were found to be statistically significant in the multivariate analysis as independent predictors of a moderate to high degree of tinnitus. The increased stiffness index of the common carotid arteries was significantly associated with the formation and severity of tinnitus. Therefore, an assessment of the carotideal system may be helpful in these patients.

  5. New Aproach in the Evaluation of Soil Stiffness Coeficients

    Directory of Open Access Journals (Sweden)

    N. Ungureanu

    2005-01-01

    Full Text Available General numerical methods based on the discretization of the surface between structure and soil in finite elements are developed and, by their help, the stiffness matrix is determined. There are considered the medium model of linear elastic, homogeneous and isotropic half-space and anisotropic half-space, respectively. In case of rigid structures or with rigid base, it is essentially for their response evaluation to know the stiffness coefficients.

  6. Design of Stiffness for Air Spring Based on ABAQUS

    OpenAIRE

    Li, Hongguang; Guo, Konghui; Chen, Shuqi; Wang, Wei; Cong, Fuzhong

    2013-01-01

    In this paper, an axisymmetric finite element (FE) model of an air spring was carried out with the software ABAQUS to design its target vertical stiffness. The bellows was simulated by the reinforced surface element. The compressed gas in the cavity of the air spring was represented by the hydrostatic fluid element. The target stiffness is obtained by modifying the valid area of the cross section. At last, the results of experiment coincided well with the simulation data. The study shows that...

  7. Can't Curb the Urge to Move? Living with Restless Legs Syndrome

    Science.gov (United States)

    ... Sleep? Wise Choices Recognizing Restless Legs Restless legs syndrome brings all 4 of these characteristics: A strong urge to move your legs, often with unpleasant feelings like tingling, burning or throbbing in the legs. Symptoms that get better ... Legs Syndrome Fact Sheet What Is Restless Legs Syndrome? Brain ...

  8. Restless Legs Syndrome and Leg Motor Restlessness in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Keisuke Suzuki

    2015-01-01

    Full Text Available Sleep disturbances are important nonmotor symptoms in Parkinson’s disease (PD that are associated with a negative impact on quality of life. Restless legs syndrome (RLS, which is characterized by an urge to move the legs accompanied by abnormal leg sensations, can coexist with PD, although the pathophysiology of these disorders appears to be different. RLS and PD both respond favorably to dopaminergic treatment, and several investigators have reported a significant relationship between RLS and PD. Sensory symptoms, pain, motor restlessness, akathisia, and the wearing-off phenomenon observed in PD should be differentiated from RLS. RLS in PD may be confounded by chronic dopaminergic treatment; thus, more studies are needed to investigate RLS in drug-naïve patients with PD. Recently, leg motor restlessness (LMR, which is characterized by an urge to move the legs that does not fulfill the diagnostic criteria for RLS, has been reported to be observed more frequently in de novo patients with PD than in age-matched healthy controls, suggesting that LMR may be a part of sensorimotor symptoms intrinsic to PD. In this paper, we provide an overview of RLS, LMR, and PD and of the relationships among these disorders.

  9. Differences in take-off leg kinetics between horizontal and vertical single-leg rebound jumps.

    Science.gov (United States)

    Kariyama, Yasushi; Hobara, Hiroaki; Zushi, Koji

    2017-06-01

    This study aimed to clarify the differences between the horizontal single-leg rebound jump (HJ) and vertical single-leg rebound jump (VJ) in terms of three-dimensional joint kinetics for the take-off leg, while focusing on frontal and transverse plane movements. Eleven male track and field athletes performed HJ and VJ. Kinematic and kinetic data were calculated using data recorded with a motion capture system and force platforms. The hip abduction torque, trunk lateral flexion torque (flexion for the swing-leg side), hip external and internal torque, trunk rotational torque, and the powers associated with these torques were larger when performing HJ because of resistance to the impact ground reaction force and because of pelvic and posture control. Pelvic rotation was noted in HJ, and this was controlled not only by the hip and trunk joint torque from the transverse plane but also by the hip abduction torque. Therefore, hip and trunk joint kinetics in the frontal and transverse plane play an important role in a single-leg jump, regardless of the jumping direction, and may also play a more important role in HJ than in VJ.

  10. Effects of warm-up on hamstring muscles stiffness: Cycling vs foam rolling.

    Science.gov (United States)

    Morales-Artacho, A J; Lacourpaille, L; Guilhem, G

    2017-12-01

    This study investigated the effects of active and/or passive warm-up tasks on the hamstring muscles stiffness through elastography and passive torque measurements. On separate occasions, fourteen males randomly completed four warm-up protocols comprising Control, Cycling, Foam rolling, or Cycling plus Foam rolling (Mixed). The stiffness of the hamstring muscles was assessed through shear wave elastography, along with the passive torque-angle relationship and maximal range of motion (ROM) before, 5, and 30 minutes after each experimental condition. At 5 minutes, Cycling and Mixed decreased shear modulus (-10.3% ± 5.9% and -7.7% ± 8.4%, respectively; P≤.0003, effect size [ES]≥0.24) and passive torque (-7.17% ± 8.6% and -6.2% ± 7.5%, respectively; P≤.051, ES≥0.28), and increased ROM (+2.9% ± 2.9% and +3.2% ± 3.5%, respectively; P≤.001, ES≥0.30); 30 minutes following Mixed, shear modulus (P=.001, ES=0.21) and passive torque (P≤.068, ES≥0.2) were still slightly decreased, while ROM increased (P=.046, ES=0.24). Foam rolling induced "small" immediate short-term decreases in shear modulus (-5.4% ± 5.7% at 5 minutes; P=.05, ES=0.21), without meaningful changes in passive torque or ROM at any time point (P≥.12, ES≤0.23). These results suggest that the combined warm-up elicited no acute superior effects on muscle stiffness compared with cycling, providing evidence for the key role of active warm-up to reduce muscle stiffness. The time between warm-up and competition should be considered when optimizing the effects on muscle stiffness. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Association of EZSCAN values with arterial stiffness in individuals without diabetes or cardiovascular disease.

    Directory of Open Access Journals (Sweden)

    Qiang Zeng

    Full Text Available BACKGROUND: The EZSCAN test was recently developed to screen for early dysglycemia through an assessment of sudomotor function. Given the associations of dysglycemia and autonomic dysfunction with the development of arterial stiffness, EZSCAN may also detect early arterial stiffness. The aim of this study was to investigate the association of EZSCAN with arterial stiffness across blood glucose levels. METHODOLOGY AND PRINCIPAL FINDINGS: A total of 5532 participants without diabetes or established cardiovascular disease were evaluated with EZSCAN. Their central systolic blood pressure (cSBP, brachial-ankle pulse wave velocity (baPWV, and ankle-brachial index (ABI were also measured. Multivariate linear regression analyses were used to assess the association between the EZSCAN value and the cSBP, baPWV, and ABI measurements in all of the participants, with additional subgroup analysis that separated participants into a normal glucose tolerance (NGT group and an impaired glucose regulation (IGR group. The frequency of the IGRs increased with quartiles of the EZSCAN value (P for trend <0.0001. The levels of cSBP and baPWV increased while the levels of ABI decreased across quartiles of EZSCAN value in both NGT and IGR individuals (P for trend <0.0001 for all. In multivariable analyses, the EZSCAN value was positively associated with cSBP (log-transformed beta = 8.20, P<0.0001 and baPWV (log-transformed beta = 1.82, P<0.0001 but inversely associated with ABI (log-transformed beta = -0.043, P<0.0001 and was independent of conventional factors. Further adjustment for fasting and postprandial glucoses did not attenuate the associations. The results were also unchanged when stratified by IGR. CONCLUSIONS AND SIGNIFICANCE: The EZSCAN results were associated with arterial stiffness independent of conventional factors, blood glucose levels, and glucose tolerance status, suggesting a probable link between the EZSCAN value and arterial stiffness

  12. Infarcted myocardium-like stiffness contributes to endothelial progenitor lineage commitment of bone marrow mononuclear cells.

    Science.gov (United States)

    Zhang, Shuning; Sun, Aijun; Ma, Hong; Yao, Kang; Zhou, Ning; Shen, Li; Zhang, Chunyu; Zou, Yunzeng; Ge, Junbo

    2011-10-01

    Optimal timing of cell therapy for myocardial infarction (MI) appears during 5 to 14 days after the infarction. However, the potential mechanism requires further investigation. This work aimed to verify the hypothesis that myocardial stiffness within a propitious time frame might provide a most beneficial physical condition for cell lineage specification in favour of cardiac repair. Serum vascular endothelial growth factor (VEGF) levels and myocardial stiffness of MI mice were consecutively detected. Isolated bone marrow mononuclear cells (BMMNCs) were injected into infarction zone at distinct time-points and cardiac function were measured 2 months after infarction. Polyacrylamide gel substrates with varied stiffness were used to mechanically mimic the infarcted myocardium. BMMNCs were plated on the flexible culture substrates under different concentrations of VEGF. Endothelial progenitor lineage commitment of BMMNCs was verified by immunofluorescent technique and flow cytometry. Our results demonstrated that the optimal timing in terms of improvement of cardiac function occurred during 7 to 14 days after MI, which was consistent with maximized capillary density at this time domains, but not with peak VEGF concentration. Percentage of double-positive cells for DiI-labelled acetylated low-density lipoprotein uptake and fluorescein isothiocyanate (FITC)-UEA-1 (ulex europaeus agglutinin I lectin) binding had no significant differences among the tissue-like stiffness in high concentration VEGF. With the decrease of VEGF concentration, the benefit of 42 kPa stiffness, corresponding to infarcted myocardium at days 7 to 14, gradually occurred and peaked when it was removed from culture medium. Likewise, combined expressions of VEGFR2(+) , CD133(+) and CD45(-) remained the highest level on 42 kPa substrate in conditions of lower concentration VEGF. In conclusion, the optimal efficacy of BMMNCs therapy at 7 to 14 days after MI might result from non-VEGF dependent

  13. Effects of Different Exercise Modes on Arterial Stiffness and Nitric Oxide Synthesis.

    Science.gov (United States)

    Hasegawa, Natsuki; Fujie, Shumpei; Horii, Naoki; Miyamoto-Mikami, Eri; Tsuji, Katsunori; Uchida, Masataka; Hamaoka, Takafumi; Tabata, Izumi; Iemitsu, Motoyuki

    2018-01-30

    Aerobic training (AT) and high-intensity intermittent training (HIIT) reduce arterial stiffness, whereas resistance training (RT) induces deterioration of or no change in arterial stiffness. However, the molecular mechanism of these effects of different exercise modes remains unclear. This study aimed to clarify the difference of different exercise effects on endothelial nitric oxide synthase (eNOS) signaling pathway and arterial stiffness in rats and humans. In the animal study, forty 10-week-old male Sprague-Dawley rats were randomly divided into 4groups: sedentary control (CON), AT (treadmill running, 60min at 30m/min, 5days/wk for 8weeks), RT (ladder-climbing, 8-10sets/day, 3days/wk for 8weeks), and HIIT (14repeats of 20-sec swimming session with 10-sec pause between sessions, 4days/wk for 6weeks from 12-week-old) groups (n=10 in each group). In the human study, we confirmed the effects of 6-week HIIT and 8-week AT interventions on central arterial stiffness and plasma nitrite/nitrate (NOx) level in untrained healthy young men in randomized controlled trial (HIIT, AT, and CON; n=7 in each group). In the animal study, the effect on aortic pulse wave velocity (PWV), as an index of central arterial stiffness, following HIIT was the same as the decrease in aortic PWV and increase in arterial eNOS/Akt phosphorylation following AT, which was not changed by RT. Negative correlation between aortic PWV and eNOS phosphorylation was observed (r=-0.38, pHIIT- and AT-induced changes in carotid-femoral PWV (HIIT -115.3±63.4 and AT -157.7±45.7 vs. CON 71.3±61.1 m/sec, each pHIIT may reduce central arterial stiffness via the increase in aortic NO bioavailability despite short time and short term and has the same effects as AT.

  14. EFFECTS OF ACUTE ECCENTRIC CONTRACTIONS ON RAT ANKLE JOINT STIFFNESS

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    Ochi Eisuke

    2007-12-01

    Full Text Available The sensation of joint stiffness is frequently observed after eccentric contractions (ECs in human, but the joint stiffness of animals after ECs has not been examined previously. This study tested whether a bout of ECs affects rat ankle joint stiffness. We also evaluate muscle passive tension in the rat hindlimb to examine the relationships of ankle joint stiffness with muscle passive tension. Anesthetized male Wistar rats (n = 23 were firmly secured on a platform in the prone position. A bout of ECs was performed on the gastrocnemius muscle with a combination of electrically induced tetanic contractions via a skin electrode and simultaneous forced dorsiflexion of the ankle joint (velocity, 15°/s; from 0°to 45°. Passive resistive torque (PRT of the ankle joint was measured to evaluate joint stiffness. Passive tension of the exposed gastrocnemius muscle was also measured when the maximum value of joint stiffness was obtained. The PRT on days 2, 3, and 4 was significantly higher than the pre-treatment value (days 2 and 4; p < 0.001, days 3; p < 0.01. The passive tension on day 4 was significantly higher than that of the sham-operated group. The muscle wet mass was identical in both groups, suggesting the absence of edema. We conclude PRT increases after ECs in rat ankle joint. We also show the possibility that it is associated with muscle passive tension, independent of edema formation

  15. Rotational and peak torque stiffness of rugby shoes.

    Science.gov (United States)

    Ballal, Moez S; Usuelli, Federico Giuseppe; Montrasio, Umberto Alfieri; Molloy, Andy; La Barbera, Luigi; Villa, Tomaso; Banfi, Giuseppe

    2014-09-01

    Sports people always strive to avoid injury. Sports shoe designs in many sports have been shown to affect traction and injury rates. The aim of this study is to demonstrate the differing stiffness and torque in rugby boots that are designed for the same effect. Five different types of rugby shoes commonly worn by scrum forwards were laboratory tested for rotational stiffness and peak torque on a natural playing surface generating force patterns that would be consistent with a rugby scrum. The overall internal rotation peak torque was 57.75±6.26 Nm while that of external rotation was 56.55±4.36 Nm. The Peak internal and external rotational stiffness were 0.696±0.1 and 0.708±0.06 Nm/deg respectively. Our results, when compared to rotational stiffness and peak torques of football shoes published in the literature, show that shoes worn by rugby players exert higher rotational and peak torque stiffness compared to football shoes when tested on the same natural surfaces. There was significant difference between the tested rugby shoes brands. In our opinion, to maximize potential performance and lower the potential of non-contact injury, care should be taken in choosing boots with stiffness appropriate to the players main playing role. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Sex Differences in Limb and Joint Stiffness in Recreational Runners

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    Sinclair Jonathan

    2015-09-01

    Full Text Available Purpose. Female runners are known to be at greater risk from chronic running injuries than age-matched males, although the exact mechanisms are often poorly understood. The aim of the current investigation was to determine if female recreational runners exhibit distinct limb and joint stiffness characteristics in relation to their male counterparts. Methods. Fourteen male and fourteen female runners ran over a force platform at 4.0 m · s-1. Lower limb kinematics were collected using an eight-camera optoelectric motion capture system operating at 250 Hz. Measures of limb and joint stiffness were calculated as a function of limb length and joint moments divided by the extent of limb and joint excursion. All stiffness and joint moment parameters were normalized to body mass. Sex differences in normalized limb and knee and ankle joint stiffness were examined statistically using independent samples t tests. Results. The results indicate that normalized limb (male = 0.18 ± 0.07, female = 0.37 ± 0.10 kN · kg · m-1 and knee stiffness (male = 5.59 ± 2.02, female = 7.34 ± 1.78 Nm · kg · rad-1 were significantly greater in female runners. Conclusions. On the basis that normalized knee and limb stiffness were shown to be significantly greater in female runners, the findings from the current investigation may provide further insight into the aetiology of the distinct injury patterns observed between sexes.

  17. Inflammatory Markers for Arterial Stiffness in Cardiovascular Diseases

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    Ioana Mozos

    2017-08-01

    Full Text Available Arterial stiffness predicts an increased risk of cardiovascular events. Inflammation plays a major role in large arteries stiffening, related to atherosclerosis, arteriosclerosis, endothelial dysfunction, smooth muscle cell migration, vascular calcification, increased activity of metalloproteinases, extracellular matrix degradation, oxidative stress, elastolysis, and degradation of collagen. The present paper reviews main mechanisms explaining the crosstalk between inflammation and arterial stiffness and the most common inflammatory markers associated with increased arterial stiffness, considering the most recent clinical and experimental studies. Diverse studies revealed significant correlations between the severity of arterial stiffness and inflammatory markers, such as white blood cell count, neutrophil/lymphocyte ratio, adhesion molecules, fibrinogen, C-reactive protein, cytokines, microRNAs, and cyclooxygenase-2, in patients with a broad variety of diseases, such as metabolic syndrome, diabetes, coronary heart disease, peripheral arterial disease, malignant and rheumatic disorders, polycystic kidney disease, renal transplant, familial Mediterranean fever, and oral infections, and in women with preeclampsia or after menopause. There is strong evidence that inflammation plays an important and, at least, partly reversible role in the development of arterial stiffness, and inflammatory markers may be useful additional tools in the assessment of the cardiovascular risk in clinical practice. Combined assessment of arterial stiffness and inflammatory markers may improve non-invasive assessment of cardiovascular risk, enabling selection of high-risk patients for prophylactic treatment or more regular medical examination. Development of future destiffening therapies may target pro-inflammatory mechanisms.

  18. Learning to control arm stiffness under static conditions.

    Science.gov (United States)

    Darainy, Mohammad; Malfait, Nicole; Gribble, Paul L; Towhidkhah, Farzad; Ostry, David J

    2004-12-01

    We used a robotic device to test the idea that impedance control involves a process of learning or adaptation that is acquired over time and permits the voluntary control of the pattern of stiffness at the hand. The tests were conducted in statics. Subjects were trained over the course of 3 successive days to resist the effects of one of three different kinds of mechanical loads: single axis loads acting in the lateral direction, single axis loads acting in the forward/backward direction, and isotropic loads that perturbed the limb in eight directions about a circle. We found that subjects in contact with single axis loads voluntarily modified their hand stiffness orientation such that changes to the direction of maximum stiffness mirrored the direction of applied load. In the case of isotropic loads, a uniform increase in endpoint stiffness was observed. Using a physiologically realistic model of two-joint arm movement, the experimentally determined pattern of impedance change could be replicated by assuming that coactivation of elbow and double joint muscles was independent of coactivation of muscles at the shoulder. Moreover, using this pattern of coactivation control we were able to replicate an asymmetric pattern of rotation of the stiffness ellipse that was observed empirically. These findings are consistent with the idea that arm stiffness is controlled through the use of at least two independent co-contraction commands.

  19. Effect of Renal Transplantation in Restless Legs Syndrome.

    Science.gov (United States)

    Kahvecioglu, Serdar; Yildiz, Demet; Buyukkoyuncu, Nilufer; Celik, Huseyin; Tufan, Fatih; Kılıç, Ahmet Kasım; Gul, Bulent; Yildiz, Abdulmecid

    2016-02-01

    Restless legs syndrome is a disorder in which patients have irresistible urge to move legs during rest. Restless legs syndrome seems to be common in end-stage renal disease. After a successful renal transplant, symptoms ameliorate with renal function improvement and restless legs syndrome is seen less in this population. Here, we aimed to investigate restless legs syndrome frequency and associated factors in renal transplant patients. In a cross-sectional study with 193 patients (116 hemodialysis patients, 45 transplant patients, and 32 controls), the presence of restless legs syndrome was assessed using the Restless Legs Syndrome Questionnaire. Medical history, demographic, and laboratory data were collected from the patients' medical records. Patients were questioned about the presence of restless legs syndrome using the Restless Legs Syndrome Questionnaire. Patients were evaluated with Beck Depression Scale for depression and Pittsburgh tests for sleep disturbances. While the rate of restless legs syndrome was similar between transplants and controls, it was significantly greater in hemodialysis patients. Hemodialysis patients and controls had similar depression scores that were higher compared with transplant patients. Pittsburgh score was similar in transplant patients and controls and significantly increased in the hemodialysis patients. The rate of insomnia was significantly higher in the hemodialysis patients compared with the other 2 groups. Logistic regression analysis revealed independent correlates of restless legs syndrome as insomnia, Beck depression score, and being on hemodialysis. Linear regression analysis showed that independent correlates of higher Pittsburgh score were higher depression score, higher age, and presence of restless legs syndrome. The prevalence of restless legs syndrome is significantly lower in transplant patients than it is in patients on maintenance dialysis. In renal transplant patients, restless legs syndrome frequency was

  20. Kinematics and dynamics analysis of a quadruped walking robot with parallel leg mechanism

    Science.gov (United States)

    Wang, Hongbo; Sang, Lingfeng; Hu, Xing; Zhang, Dianfan; Yu, Hongnian

    2013-09-01

    It is desired to require a walking robot for the elderly and the disabled to have large capacity, high stiffness, stability, etc. However, the existing walking robots cannot achieve these requirements because of the weight-payload ratio and simple function. Therefore, Improvement of enhancing capacity and functions of the walking robot is an important research issue. According to walking requirements and combining modularization and reconfigurable ideas, a quadruped/biped reconfigurable walking robot with parallel leg mechanism is proposed. The proposed robot can be used for both a biped and a quadruped walking robot. The kinematics and performance analysis of a 3-UPU parallel mechanism which is the basic leg mechanism of a quadruped walking robot are conducted and the structural parameters are optimized. The results show that performance of the walking robot is optimal when the circumradius R, r of the upper and lower platform of leg mechanism are 161.7 mm, 57.7 mm, respectively. Based on the optimal results, the kinematics and dynamics of the quadruped walking robot in the static walking mode are derived with the application of parallel mechanism and influence coefficient theory, and the optimal coordination distribution of the dynamic load for the quadruped walking robot with over-determinate inputs is analyzed, which solves dynamic load coupling caused by the branches’ constraint of the robot in the walk process. Besides laying a theoretical foundation for development of the prototype, the kinematics and dynamics studies on the quadruped walking robot also boost the theoretical research of the quadruped walking and the practical applications of parallel mechanism.

  1. The impact of aerobic exercise training on arterial stiffness in pre- and hypertensive subjects: a systematic review and meta-analysis.

    Science.gov (United States)

    Montero, David; Roche, Enrique; Martinez-Rodriguez, Alejandro

    2014-05-15

    Debate concerning aerobic exercise decreasing arterial stiffness in pre- and hypertensive individuals still exists. We sought to systematically review and quantify the effect of aerobic exercise training on arterial stiffness in pre- and hypertensive subjects. MEDLINE, Cochrane, Scopus and Web of Science were searched up until August 2013 for trials assessing the effect of aerobic exercise interventions lasting 4 or more weeks on arterial stiffness in (pre)hypertensive subjects. Standardized mean difference (SMD) in arterial stiffness parameters (PWV, B-stiffness, Compliance, AIx) was calculated using a random-effects model. Subgroup and meta-regression analyses were used to study potential moderating factors. Fourteen trials comprising a total of 472 (pre)hypertensive subjects met the inclusion criteria. Arterial stiffness was not significantly reduced by aerobic training in (pre)hypertensive subjects (14 trials, SMD=-0.19; P=.06). Likewise, post-intervention arterial stiffness was similar between the aerobic exercise-trained and control (pre)hypertensive subjects (8 trials, SMD=-0.10; P=.43). Neither heterogeneity nor publication bias was detected in either of these analyses. In the subgroup analyses, arterial stiffness was significantly reduced in aerobic exercise-trained (pre)hypertensive subgroups below the median value in post minus pre-intervention systolic blood pressure (SBP) (SMD=-0.38, P=.04) and in subgroups above the median value in the duration of the intervention (SMD=-0.28, P=.03). Similar results were obtained in the meta-regression analysis. Arterial stiffness is not reduced in (pre)hypertensive subjects in response to aerobic training unless associated with a substantial reduction in SBP and/or prolonged duration. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  2. ANTIMICROBIOLOGICAL EFFECTS OF NEW NATURAL ANTISEPTIC FORMULATION ON NON-INFECTED VENOUS LEG ULCER: PILOT STUDY

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    Ivana Binić

    2011-09-01

    Full Text Available Venous leg ulcers represent a significant public health problem that will increase as the population ages. Numerous herbs and their extracts are potentially conducive to wound healing, including the ability to serve as antimicrobial, antifungal, astringent etc. The aim of the study was to establish the in-vivo antimicrobial effects of herbal hydrogel formulation DermaplantG. The major components of the DermaplantG were the extracts of Allii bulbus, Hyperici herba and extract of Calendulae flos. A total of 12 patients with non-infected venous leg ulcers were treated twice daily, for 5 weeks, with new hydrogel formulation. All ulcers showed clinical signs of contamination or colonization without signs of systemic infection. Premoistening the swab with sterile saline was considered when the surface of the wound was dry. The tip of the swab was rolled on its side in a zigzag pattern for at least one full rotation. Standard methods for isolation and identification of aerobic and anaerobic bacteria were used. On baseline assessment, a large number of different types of bacteria were detected in all venous leg ulcers. S. aureus and P. aeruginosa were isolated from almost all controls.On baseline, mixed bacterial flora (50% was isolated in six venous leg ulcers (five ulcers with S. aureus-P. aeruginosa and one ulcer with E.coli-Enterobacter spp-P.aeruginosa. At the end of the treatment in DermaplantG group in 8 venous ulcers were detected S. aureus (66.66% and P. aeruginosa (16.66%, and one venous leg ulcers was detected as sterile (8.33%. The number of different types of isolated bacterial species decreased significantly (P<0.05 after the use of DermaplantG herbal preparations. Therapy in DermaplantG group was administered without any side effects.The preliminary results of this pilot study demonstrate potential antimicrobial effects of herbal therapy on non-infected venous leg ulcers.

  3. Restless legs syndrome and nocturnal leg cramps: a review and guide to diagnosis and treatment.

    Science.gov (United States)

    Tipton, Philip W; Wszołek, Zbigniew K

    2017-12-22

    Restless legs syndrome (RLS) and nocturnal leg cramps (NLCs) are common disorders affecting 7.0% and 24.1% of the population in some European countries, respectively. Patients suffering from RLS experience uncomfortable nocturnal sensations in the legs with the urge to move that dissipates while moving. NLC is characterized by abrupt muscle contraction, most often in the gastrocnemius or foot muscles, which occurs at night and may result in significant sleep disturbances. The diagnosis of these disorders has presented a challenge to health care providers because of symptom overlap with other sensory and motor disturbances with nocturnal predominance. Treatment options and approaches are lacking, partially because of our currently incomplete understanding of the pathophysiological mechanisms underlying these conditions. We reviewed the medical literature to provide a comprehensive assessment of RLS and NLC with a focus on improved diagnostic accuracy and treatment approaches.

  4. Arm stiffness during assisted movement after stroke: the influence of visual feedback and training.

    Science.gov (United States)

    Piovesan, Davide; Morasso, Pietro; Giannoni, Psiche; Casadio, Maura

    2013-05-01

    Spasticity and muscular hypertonus are frequently found in stroke survivors and may have a significant effect on functional impairment. These abnormal neuro-muscular properties, which are quantifiable by the net impedance of the hand, have a direct consequence on arm mechanics and are likely to produce anomalous motor paths. Literature studies quantifying limb impedance in stroke survivors have focused on multijoint static tasks and single joint movements. Despite this research, little is known about the role of sensory motor integration in post-stroke impedance modulation. The present study elucidates this role by integrating an evaluation of arm impedance into a robotically mediated therapy protocol. Our analysis had three specific objectives: 1) obtaining a reliable measure for the mechanical proprieties of the upper limb during robotic therapy; 2) investigating the effects of robot-assisted training and visual feedback on arm stiffness and viscosity; 3) determining if the stiffness measure and its relationship with either training or visual feedback depend on arm position, speed, and level of assistance. This work demonstrates that the performance improvements produced by minimally assistive robot training are associated with decreased viscosity and stiffness in stroke survivors' paretic arm and that these mechanical impedance components are partially modulated by visual feedback.

  5. Experimental Characterization of Stress- and Strain-Dependent Stiffness in Grouted Rock Masses.

    Science.gov (United States)

    Kim, Ji-Won; Chong, Song-Hun; Cho, Gye-Chun

    2018-03-29

    Grouting of fractured rock mass prior to excavation results in grout-filled discontinuities that govern the deformation characteristics of a site. The influence of joint characteristics on the properties of grouted rocks is important in assessing the effects of grouting on jointed rock mass. However, grouting remains a predominantly empirical practice and the effects of grouting on rock joint behavior and material properties have yet to be accurately assessed. Granular materials, including jointed rocks, typically display nonlinear strain-dependent responses that can be characterized by the shear modulus degradation curve. In this study, the effects of grouting on the strain-dependent shear stiffness of jointed rock mass were investigated at the small-strain (below 10 -5 ) and mid-strain (10 -5 to 10 -3 ) ranges using the quasi-static resonant column test and rock mass dynamic test devices. The effects of curing time, axial stress, initial joint roughness, and grouted joint thickness were examined. The results show that (1) grouting of rock joints leads to decreased stress sensitivity and increased small-strain shear stiffness for all tested samples; (2) the grouted rock samples display similar modulus degradation characteristics as the applied grout material; (3) the initial joint roughness determines the stress-dependent behaviors and general stiffness range of the jointed and grouted rocks, but the strain-dependent behaviors are dependent on the properties of the grout material; (4) increased grouted joint thickness results in larger contribution of the grout properties in the overall grouted rock mass.

  6. Effects of hamstring stretching on passive muscle stiffness vary between hip flexion and knee extension maneuvers.

    Science.gov (United States)

    Miyamoto, N; Hirata, K; Kanehisa, H

    2017-01-01

    The purpose of this study was to examine whether the effects of hamstring stretching on the passive stiffness of each of the long head of the biceps femoris (BFl), semitendinosus (ST), and semimembranosus (SM) vary between passive knee extension and hip flexion stretching maneuvers. In 12 male subjects, before and after five sets of 90 s static stretching, passive lengthening measurements where knee or hip joint was passively rotated to the maximal range of motion (ROM) were performed. During the passive lengthening, shear modulus of each muscle was measured by ultrasound shear wave elastography. Both stretching maneuvers significantly increased maximal ROM and decreased passive torque at a given joint angle. Passive knee extension stretching maneuver significantly reduced shear modulus at a given knee joint angle in all of BFl, ST, and SM. In contrast, the stretching effect by passive hip flexion maneuver was significant only in ST and SM. The present findings indicate that the effects of hamstring stretching on individual passive muscles' stiffness vary between passive knee extension and hip flexion stretching maneuvers. In terms of reducing the muscle stiffness of BFl, stretching of the hamstring should be performed by passive knee extension rather than hip flexion. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. Acupuncture therapy improves vascular hemodynamics and stiffness in middle-age hypertensive individuals.

    Science.gov (United States)

    Terenteva, Nina; Chernykh, Oksana; Sanchez-Gonzalez, Marcos A; Wong, Alexei

    2018-02-01

    Acupuncture (ACU) is becoming a more common practice among hypertensive individuals. However, the reported therapeutic effects of ACU in lowering brachial blood pressure (BP) are ambiguous. Therefore, evaluating more sensitive markers of arterial functioning might unveil the protective effects of ACU on hypertension. We examined the effects of an 8-week ACU therapy intervention on vascular hemodynamics and stiffness in middle-age hypertensive individuals. Participants were randomly assigned to either ACU (n = 23) or a control group (n = 22). Brachial and aortic BP, wave reflection (AIx) and arterial stiffness (SI) were measured before and after 8 weeks. There was a significant group x time interaction (P < 0.05) for brachial and aortic BP, AIx and SI which significantly decreased (P < 0.05) following ACU but not after control. ACU led to reductions in brachial and aortic BP, wave reflection and arterial stiffness in middle-age hypertensive individuals. ACU might be effective in the prevention and treatment of hypertension. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Stiffness of a granular base under optimum and saturated water contents

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    Fausto Andrés Molina Gómez

    2016-07-01

    Full Text Available Objective: This research work addressed the comparison of the stiffness of a granular base under optimum water content and total saturation conditions. Methodology: The methodology focused in the development of an experimental program and the computation of a function, which permits to assess the elastic moduli of the material. A triaxial cell equipped by local LVDT transducers, capable of managing different stress paths, was used to measure the small-strain stiffness of a granular base under two different conditions of moisture. The material was compacted with optimum water content and subjected to a series of loading-unloading cycles under isotropic conditions. In addition, identical specimens were prepared to be saturated and the experimental procedure was repeated to obtain the moduli in these new circumstances. The moduli were assessed by a hyperbolic model, and its relationship with the confining pressure was computed. Results: The results indicated that numerical model was adjusted to the experimental results. In addition, it was found that the elastic moduli decrease 3% to 8% in conditions of total saturation versus the condition of optimum water contents. Conclusions: The small-strain stiffness in the granular base depends on the water content, and the moisture can affect the deformation in the pavement structures.

  9. Lymphedema treatment decreases pain intensity in lipedema.

    Science.gov (United States)

    Szolnoky, G; Varga, E; Varga, M; Tuczai, M; Dósa-Rácz, E; Kemény, L

    2011-12-01

    Lipedema is a disproportional obesity featuring light pressure-induced or spontaneous pain. On the basis of our clinical observations, lymphedema therapy, as practiced in our clinic, reduces the perception of pain beyond leg volume reduction. We therefore aimed to measure pain intensity prior and subsequent to treatment. 38 women with lipedema were enrolled in the study with 19 patients undergoing treatment and 19 serving as the control group using exclusively moisturizers. Treatment consisted of once daily manual lymph drainage (MLD), intermittent pneumatic compression (IPC), and multilayered short-stretch bandaging performed throughout a 5-day-course. Pain was evaluated with a 10-item questionnaire, a pain rating scale (PRS), and the Wong-Baker Faces scale. Treatment resulted in a significant reduction of pain with a decrease in mean scores of all three measures. In the control group, only PRS showed significant decrease. Our study results indicate that this treatment regimen not only reduces leg volume and capillary fragility, but also improves pain intensity in patients with lipedema.

  10. Immobilization tests and periodic leg movements in sleep for the diagnosis of restless leg syndrome.

    Science.gov (United States)

    Montplaisir, J; Boucher, S; Nicolas, A; Lesperance, P; Gosselin, A; Rompré, P; Lavigne, G

    1998-03-01

    Patients with restless leg syndrome (RLS) complain of motor restlessness, usually occurring while they rest in the evening. Two immobilization tests have been described to assess leg restlessness in these patients. In the first test, the patient sits in bed with his or her legs outstretched while electromyograms are recorded from right and left anterior tibialis muscles for an hour (Suggested Immobilization Test [SIT]); in the second test, the legs are immobilized in a stretcher (Forced Immobilization Test [FIT]). In the current study, the SIT and the FIT were compared in patients with RLS and normal control subjects matched for age and sex. More leg movements were seen in patients than in controls during immobilization tests, especially the SIT. These movements were periodic, occurring at a frequency of approximately one every 12 seconds. The SIT (index > 40) was found to discriminate between RLS and control subjects better than the FIT (index > 25). Patients were also recorded during two consecutive nights to measure periodic leg movements in sleep (PLMS). A SIT index greater than 40 and a PLMS index greater than 11 (highest PLMS index of 2 consecutive nights) were found to discriminate patients with RLS from control subjects with similar power. With each of these two measures, the clinical diagnosis was correctly predicted in 81% of patients and 81% of the control subjects. The SIT has several advantages over the measure of the PLMS index; it does not require an all-night polygraphic recording and can be administered several times a day to measure circadian fluctuation of motor restlessness.

  11. Hydration Status Is Associated with Aortic Stiffness, but Not with Peripheral Arterial Stiffness, in Chronically Hemodialysed Patients

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    Daniel Bia

    2015-01-01

    Full Text Available Background. Adequate fluid management could be essential to minimize high arterial stiffness observed in chronically hemodialyzed patients (CHP. Aim. To determine the association between body fluid status and central and peripheral arterial stiffness levels. Methods. Arterial stiffness was assessed in 65 CHP by measuring the pulse wave velocity (PWV in a central arterial pathway (carotid-femoral and in a peripheral pathway (carotid-brachial. A blood pressure-independent regional arterial stiffness index was calculated using PWV. Volume status was assessed by whole-body multiple-frequency bioimpedance. Patients were first observed as an entire group and then divided into three different fluid status-related groups: normal, overhydration, and dehydration groups. Results. Only carotid-femoral stiffness was positively associated (P<0.05 with the hydration status evaluated through extracellular/intracellular fluid, extracellular/Total Body Fluid, and absolute and relative overhydration. Conclusion. Volume status and overload are associated with central, but not peripheral, arterial stiffness levels with independence of the blood pressure level, in CHP.

  12. Leg movement tracking in automatic video-based one-leg stance evaluation.

    Science.gov (United States)

    Kawa, Jacek; Stępień, Paula; Kapko, Wojciech; Niedziela, Aleksandra; Derejczyk, Jarosław

    2018-04-01

    Falls are a major risk in elder population. Early diagnosis is therefore an important step towards increasing the safety of elders. One of the common diagnostic tests is the Berg Balance Scale (BBS), consisting of 14 exercises arranged from the easiest (sitting-to-standing) to the most demanding (one-leg stance). In this study a novel approach to the automatic assessment of the time in which the patient can remain in the one-leg stance position without loosing balance is introduced. The data is collected using a regular video camera. No markers, special garments, or system calibration are required. Two groups are examined. The first group consists of 16 students: healthy, young adults (12 female, 4 male, avg. 20yrs±1). The second group consists of 50 elders (39 female, 11 male, avg. 78.8yrs±5.9). Data (short, one minute recordings) are collected in a controlled environment using a digital video recorder (50fps, 1920×1080) fixed to a tripod. Data are processed off-line. First, the region of interest is determined. Next, the Kanade-Lucas-Tomasi tracking is performed. Best tracks are selected based on the registered vertical movement and two tracks are obtained corresponding to the left and right leg movements. Tracks are later subjected to the sparse signal baseline estimation, denoising and thresholding to detect the raised leg. Results are compared frame-wise to the ground truth reference obtained in the manual processing procedure. Both legs are evaluated in the elder group (in all cases several attempts featuring both legs were registered), resulting in 89.18%±11.27% DICE, 93.07%±5.43% sensitivity and 96.94%±6.11% specificity values for both legs. The signal of a single leg is evaluated in the student group (in all cases only one attempt was needed to perform the full examination) resulting in 98.96%±1.2% DICE, 98.78%±1.65% sensitivity and 98.73%±2.69% specificity values. This is the first step towards a video-based system enabling the automatic

  13. Relationship between Leg Mass, Leg Composition and Foot Velocity on Kicking Accuracy in Australian Football.

    Science.gov (United States)

    Hart, Nicolas H; Nimphius, Sophia; Spiteri, Tania; Cochrane, Jodie L; Newton, Robert U

    2016-06-01

    Kicking a ball accurately over a desired distance to an intended target is arguably the most important skill to acquire in Australian Football. Therefore, understanding the potential mechanisms which underpin kicking accuracy is warranted. The aim of this study was to examine the relationship between leg mass, leg composition and foot velocity on kicking accuracy in Australian Football. Thirty-one Australian Footballers (n = 31; age: 22.1 ± 2.8 years; height: 1.81 ± 0.07 m; weight: 85.1 ± 13.0 kg; BMI: 25.9 ± 3.2) each performed ten drop punt kicks over twenty metres to a player target. Athletes were separated into accurate (n = 15) and inaccurate (n = 16) kicking groups. Leg mass characteristics were assessed using whole body DXA scans. Foot velocity was determined using a ten-camera optoelectronic, three-dimensional motion capture system. Interactions between leg mass and foot velocity evident within accurate kickers only (r = -0.670 to -0.701). Relative lean mass was positively correlated with kicking accuracy (r = 0.631), while no relationship between foot velocity and kicking accuracy was evident in isolation (r = -0.047 to -0.083). Given the evident importance of lean mass, and its interaction with foot velocity for accurate kickers; future research should explore speed-accuracy, impulse-variability, limb co-ordination and foot-ball interaction constructs in kicking using controlled with-in subject studies to examine the effects of resistance training and skill acquisition programs on the development of kicking accuracy. Key pointsAccurate kickers expressed a very strong inverse relationship between leg mass and foot velocity. Inaccurate kickers were unable to replicate this, with greater volatility in their performance, indicating an ability of accurate kickers to mediate foot velocity to compensate for leg mass in order to deliver the ball over the required distance.Accurate kickers exhibited larger quantities of relative lean mass and lower quantities

  14. Amiloride Improves Endothelial Function and Reduces Vascular Stiffness in Female Mice Fed a Western Diet

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    Luis A. Martinez-Lemus

    2017-06-01

    Full Text Available Obese premenopausal women lose their sex related cardiovascular disease protection and develop greater arterial stiffening than age matched men. In female mice, we have shown that consumption of a Western diet (WD, high in fat and refined sugars, is associated with endothelial dysfunction and vascular stiffening, which occur via activation of mineralocorticoid receptors and associated increases in epithelial Na+ channel (ENaC activity on endothelial cells (EnNaC. Herein our aim was to determine the effect that reducing EnNaC activity with a very-low-dose of amiloride would have on decreasing endothelial and arterial stiffness in young female mice consuming a WD. To this end, we fed female mice either a WD or control diet and treated them with or without a very-low-dose of the ENaC-inhibitor amiloride (1 mg/kg/day in the drinking water for 20 weeks beginning at 4 weeks of age. Mice consuming a WD were heavier and had greater percent body fat, proteinuria, and aortic stiffness as assessed by pulse-wave velocity than those fed control diet. Treatment with amiloride did not affect body weight, body composition, blood pressure, urinary sodium excretion, or insulin sensitivity, but significantly reduced the development of endothelial and aortic stiffness, aortic fibrosis, aortic oxidative stress, and mesenteric resistance artery EnNaC abundance and proteinuria in WD-fed mice. Amiloride also improved endothelial-dependent vasodilatory responses in the resistance arteries of WD-fed mice. These results indicate that a very-low-dose of amiloride, not affecting blood pressure, is sufficient to improve endothelial function and reduce aortic stiffness in female mice fed a WD, and suggest that EnNaC-inhibition may be sufficient to ameliorate the pathological vascular stiffening effects of WD-induced obesity in females.

  15. Influence of antiviral therapy on the liver stiffness in chronic HBV hepatitis.

    Science.gov (United States)

    Rinaldi, Luca; Ascione, Antonio; Messina, Vincenzo; Rosato, Valerio; Valente, Giovanna; Sangiovanni, Vincenzo; Zampino, Rosa; Marrone, Aldo; Fontanella, Luca; de Rosa, Nicolina; Orabona, Pasquale; Buonomo, Carmela; Chirianni, Antonio; Adinolfi, Luigi Elio; Piai, Guido

    2018-04-01

    The aim of this study was to evaluate the effects of antiviral therapy on liver stiffness measurement (LSM). Two hundred HBV patients were enrolled from four hospital centers in southern Italy; median age was 50.7 (25-75) males were 68%; 171 patients underwent to liver biopsy and 200 patients had LSM at baseline and 189 at the end of follow-up. One hundred and forty-nine patients were treated with nucleos(t)ide analogs, while 51 patients were untreated. The cutoffs of the LSM, related to the fibrosis stages, were as follows: non-advanced fibrosis ≤ 8.1 kPa and advanced fibrosis ≥ 8.2 Kpa. At baseline, the median value of LSM was 14.1 kPa for advanced fibrosis/cirrhosis and 6.9 kPa for non-advanced fibrosis. LSM was performed at 24 months from the start of therapy. The treated patients (68% received Entecavir and 32% Tenofovir) showed a decrease in liver stiffness measurement of 1.5 kPa (p < 0.001) in non-advanced fibrosis and of 6 kPa (p < 0.001) in advanced fibrosis/cirrhosis. In the patients not undergoing antiviral treatment, no statistically significant change of the LSM was observed (p = 0.26). A logistic binary regression model showed that the only independent factor associated with a significant change in the LSM was the liver stiffness value at baseline (odd ratio 2.855; 95% CI 1.456-5.788; (p = 0.007). Long-term antiviral therapy induced a significant reduction of liver stiffness measurement and this result may be related to the reduction of liver fibrosis.

  16. Meal ingestion markedly increases liver stiffness suggesting the need for liver stiffness determination in fasting conditions.

    Science.gov (United States)

    Alvarez, Daniel; Orozco, Federico; Mella, José María; Anders, Maria; Antinucci, Florencia; Mastai, Ricardo

    2015-01-01

    The introduction of noninvasive liver stiffness (LS) determination has heralded a new stage in the diagnosis and treatment of liver fibrosis. We evaluated the effect of food intake on LS in patients with different degrees of liver disease. We evaluated 24 patients (F≤1, n=11 and F> 1, n=13). LS (Fibroscan®) and portal blood flow (PBF) (Doppler ultrasound) were studied before and 30min after ingestion of a standard liquid meal. Food intake increased PBF (51±10%, p1). Hemodynamic and LS values returned to baseline pre-meal levels within 2hours. LS increases markedly after ingestion of a standard meal, irrespective of the degree of fibrosis. Our results strongly suggest that LS should be measured in fasting conditions. Copyright © 2015 Elsevier España, S.L.U. and AEEH y AEG. All rights reserved.

  17. Interpretation of liver stiffness measurement-based approach for the monitoring of hepatitis B patients with antiviral therapy: A 2-year prospective study.

    Science.gov (United States)

    Liang, X; Xie, Q; Tan, D; Ning, Q; Niu, J; Bai, X; Chen, S; Cheng, J; Yu, Y; Wang, H; Xu, M; Shi, G; Wan, M; Chen, X; Tang, H; Sheng, J; Dou, X; Shi, J; Ren, H; Wang, M; Zhang, H; Gao, Z; Chen, C; Ma, H; Chen, Y; Fan, R; Sun, J; Jia, J; Hou, J

    2018-03-01

    Liver biopsy is not routinely performed in treated chronic hepatitis B. Liver stiffness measurement has been validated for noninvasive liver fibrosis assessment in pretreatment chronic hepatitis B but has not been assessed for fibrosis monitoring during antiviral therapy. Liver stiffness was systemically monitored by Fibroscan ® every 6 months in a cohort of patients with hepatitis B receiving antiviral therapy and compared with liver biopsies at baseline and week 104. A total of 534 hepatitis B e antigen-positive treatment-naive patients receiving telbivudine-based therapy with qualified liver stiffness measurement at baseline and week 104 were analyzed, 164 of which had adequate paired liver biopsies. Liver stiffness decreased rapidly (-2.2 kPa/24 weeks) in parallel with alanine aminotransferase (ALT) from 8.6 (2.6-49.5) kPa at baseline to 6.1 (2.2-37.4) kPa at week 24. Interestingly, liver stiffness decreased slowly (-0.3 kPa/24 weeks) but continually from week 24 to week 104 (6.1 vs 5.3 kPa, P < .001) while ALT levels remained stable within the normal range. More importantly, liver stiffness declined significantly irrespective of baseline ALT levels and liver necroinflammation grades. From baseline to week 104, the proportion of patients with no or mild fibrosis (Ishak, 0-2) increased from 74.4% (122/164) to 93.9% (154/164). Multivariate analysis revealed that percentage decline of 52-week liver stiffness from baseline was independently associated with 104-week liver fibrosis regression (odds ratio, 3.742; P = .016). Early decline of 52-week liver stiffness from baseline may reflect the remission of both liver inflammation and fibrosis and was predictive of 104-week fibrosis regression in treated patients with chronic hepatitis B. © 2017 John Wiley & Sons Ltd.

  18. On the biomimetic design of agile-robot legs.

    Science.gov (United States)

    Garcia, Elena; Arevalo, Juan Carlos; Muñoz, Gustavo; Gonzalez-de-Santos, Pablo

    2011-01-01

    The development of functional legged robots has encountered its limits in human-made actuation technology. This paper describes research on the biomimetic design of legs for agile quadrupeds. A biomimetic leg concept that extracts key principles from horse legs which are responsible for the agile and powerful locomotion of these animals is presented. The proposed biomimetic leg model defines the effective leg length, leg kinematics, limb mass distribution, actuator power, and elastic energy recovery as determinants of agile locomotion, and values for these five key elements are given. The transfer of the extracted principles to technological instantiations is analyzed in detail, considering the availability of current materials, structures and actuators. A real leg prototype has been developed following the biomimetic leg concept proposed. The actuation system is based on the hybrid use of series elasticity and magneto-rheological dampers which provides variable compliance for natural motion. From the experimental evaluation of this prototype, conclusions on the current technological barriers to achieve real functional legged robots to walk dynamically in agile locomotion are presented.

  19. On the Biomimetic Design of Agile-Robot Legs

    Directory of Open Access Journals (Sweden)

    Pablo Gonzalez-de-Santos

    2011-11-01

    Full Text Available The development of functional legged robots has encountered its limits in human-made actuation technology. This paper describes research on the biomimetic design of legs for agile quadrupeds. A biomimetic leg concept that extracts key principles from horse legs which are responsible for the agile and powerful locomotion of these animals is presented. The proposed biomimetic leg model defines the effective leg length, leg kinematics, limb mass distribution, actuator power, and elastic energy recovery as determinants of agile locomotion, and values for these five key elements are given. The transfer of the extracted principles to technological instantiations is analyzed in detail, considering the availability of current materials, structures and actuators. A real leg prototype has been developed following the biomimetic leg concept proposed. The actuation system is based on the hybrid use of series elasticity and magneto-rheological dampers which provides variable compliance for natural motion. From the experimental evaluation of this prototype, conclusions on the current technological barriers to achieve real functional legged robots to walk dynamically in agile locomotion are presented.

  20. Loading and performance of the support leg in kicking.

    Science.gov (United States)

    Ball, Kevin

    2013-09-01

    The punt kick is important in many football codes and support leg kinematics and ground reaction forces have been implicated in injury and performance in kicking. To evaluate ground reaction forces and support leg kinematics in the punt kick. Cross sectional study. Seven elite Australian football players performed maximal kicks into a net using both the preferred and non-preferred legs. A force plate measured ground reaction forces and an optical motion capture system (200Hz) collected kinematic data during the stance phase of the kick. Preferred and non-preferred legs were compared and performance was evaluated by correlating parameters with foot speed at ball contact. Vertical forces were larger than running at a similar speed but did not reach levels that might be considered an injury risk. Braking forces were directed solely posteriorly, as for soccer kicks, but lateral force patterns varied with some players experiencing greater forces medially and others laterally. A more extended support leg, larger peak vertical and braking force during the stance phase and a shorter stance contact time was associated with larger kick leg foot speed at ball contact. No difference existed between the preferred and non-preferred legs for ground reaction forces or support leg mechanics. To punt kick longer, a straighter support leg, less time on the ground and stronger braking should be encouraged. Conditioning the support leg to provide stronger braking potential is recommended. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  1. On the Biomimetic Design of Agile-Robot Legs

    Science.gov (United States)

    Garcia, Elena; Arevalo, Juan Carlos; Muñoz, Gustavo; Gonzalez-de-Santos, Pablo

    2011-01-01

    The development of functional legged robots has encountered its limits in human-made actuation technology. This paper describes research on the biomimetic design of legs for agile quadrupeds. A biomimetic leg concept that extracts key principles from horse legs which are responsible for the agile and powerful locomotion of these animals is presented. The proposed biomimetic leg model defines the effective leg length, leg kinematics, limb mass distribution, actuator power, and elastic energy recovery as determinants of agile locomotion, and values for these five key elements are given. The transfer of the extracted principles to technological instantiations is analyzed in detail, considering the availability of current materials, structures and actuators. A real leg prototype has been developed following the biomimetic leg concept proposed. The actuation system is based on the hybrid use of series elasticity and magneto-rheological dampers which provides variable compliance for natural motion. From the experimental evaluation of this prototype, conclusions on the current technological barriers to achieve real functional legged robots to walk dynamically in agile locomotion are presented. PMID:22247667

  2. Association between serum hepcidin level and restless legs syndrome.

    Science.gov (United States)

    Dauvilliers, Yves; Chenini, Sofiene; Vialaret, Jérôme; Delaby, Constance; Guiraud, Lily; Gabelle, Audrey; Lopez, Regis; Hirtz, Christophe; Jaussent, Isabelle; Lehmann, Sylvain

    2018-02-08

    To better understand the role of iron homeostasis dysregulation in restless legs syndrome, we compared serum hepcidin and ferritin levels in drug-free patients with primary restless legs syndrome and healthy controls and studied the relationship between hepcidin level and restless legs syndrome severity. One hundred and eight drug-free patients with primary restless legs syndrome (65 women; median age, 61.5 years) and 45 controls (28 women; median age, 53.9 years) were enrolled. Inclusion criteria were: normal ferritin level (>50 ng/mL) and absence of iron disorders, chronic renal or liver failure, and inflammatory or neurological diseases. Each subject underwent a thorough clinical examination and a polysomnography assessment. Serum hepcidin-25 was quantified using a validated mass spectrometry method. Restless legs syndrome severity was evaluated according to the International Restless Legs Syndrome Study Group. Despite no group difference between normal ferritin levels and demographic features, serum hepcidin level and hepcidin/ferritin ratio were higher in patients than in controls. Hepcidin level and hepcidin/ferritin ratio, but not ferritin level, were positively correlated with periodic leg movements during sleep and wakefulness in the whole sample. Hepcidin level seem to be associated with restless legs syndrome severity in a complex U-shaped relationship, without relationship with age at restless legs syndrome onset, positive family history, sleep and depressive symptoms, genetic background, and polysomnographic measurements. No relationship was found between ferritin level and restless legs syndrome severity. In drug-free patients with primary restless legs syndrome, hepcidin level is higher than in controls and may be associated with restless legs syndrome clinical severity. This result emphasizes the complex peripheral iron metabolism deregulation in restless legs syndrome, opening potential perspectives for a personalized approach with a hepcidin

  3. Psychological stress and arterial stiffness in Korean Americans.

    Science.gov (United States)

    Logan, Jeongok G; Barksdale, Debra J; Carlson, John; Carlson, Barbara W; Rowsey, Pamela J

    2012-07-01

    Arterial stiffness is identified as a causative factor for hypertension. The purpose of this study was to explore the relationship between psychological stress and arterial stiffness in Korean Americans. A convenience sample of 102 Korean Americans (aged 21-60 years, 60% women) was recruited from North Carolina. Psychological stress was measured by the Perceived Stress Scale, the Social, Attitudinal, Familiar, and Environmental (SAFE) Acculturative Stress Scale, and the Spielberger's State-Trait Anxiety Inventory. Arterial stiffness was measured by carotid-femoral pulse wave velocity (cfPWV) using the SphygmoCor system (AtCor Medical, Australia). This study shows that the emotional stress response, measured by anxiety, significantly predicted arterial stiffness (β=.25, p=.008), independently of such confounding factors as age, mean arterial pressure (MAP), gender, body mass index, smoking, education, and income. Anxiety was neither related to age (r=.12, p=.212) nor MAP (r=.14, p=.151). Additionally, this sample of Korean Americans had higher levels of psychological stress when compared to previous findings from studies of other racial/ethnic groups in the U.S. Findings demonstrate that anxiety is a significant and independent determinant of arterial stiffness. Given that anxiety was not related to MAP, these findings suggest that arterial stiffness may be a pathway to explain the connection between anxiety and hypertension risk. Studies that scrutinize the relationship between anxiety and arterial stiffness are an important next step for future research. Further studies are also recommended to explore cultural factors and individual characteristics that may affect anxiety in Korean Americans. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Sleep disturbances in restless legs syndrome

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    Jović Jasmina

    2018-01-01

    Full Text Available Background/Aim. Resteless legs syndrome (RLS is chronical neurological disorder characterized by urge to move legs that is usually accompanied by unpleasant sensations in the lower extremities. Sleep disturbance is one of the main accompanying symptoms of RLS which exists in approximatelly 90% of patients. Impairment of sleep is related to daily sleepiness, depressive and anxiety disorders. The aim of this study was to detect frequency and characterisitics of sleep-related symptoms in patients with RLS, and its impairrment to daily sleepiness, fatique, anxiety and depression. Methods. We have examinated 94 patients with RLS. The diagnose of RLS was based on questionnaire with 4 specific questions according to the International Restless Legs Syndrome Study Group (IRLSSG criteria updated in 2003. Severity of symptoms was astimated with IRLSSG Rating Scale, depression and anxiety with Hamilton Depression Rating Scale (HDRS and Hamilton Anxiety Rating Scale (HARS and sleepiness with Epworth Sleepiness scale (ESS. We astimated sleep characteristics and disturbances with specific questionnaire. Results. In our study 79.9% of patients had sleep-related symptoms. Average sleep duration was 6.50 ± 1.42 hours, with average frequency of awakening 2.34 ± 1.69 times per night. Average ESS score was 5.12 ± 4.08 (0–17. Patients with more severe symptoms had higher degree of sleepiness (p = 0.005. Patients with higher symptoms frequency, significantly more often had sleep disturbance (p = 0.016, tiredness and daily sleepiness (p = 0.001. Daily sleepiness (ESS also significantly correlates with depression (p < 0.05 and anxiety (p = 0.012. Conclusion. Our results confirm that sleep disturbances are one of the key accompanying symptoms of RLS which cause daily sleepiness, tiredness, depression and anxiety. Therefore, their early recognition and appropriate treatment must be a priority in RLS patients.

  5. [Bow legged adjectives in ancient literature].

    Science.gov (United States)

    Simon, Frantisek; Steger, Florian

    2011-01-01

    This article addresses the issue of capturing the medical entity called 'curved legs' in a terminologically exact way. In so doing, it refers to the long-lasting process of differentiation of exact nuances of meaning in Ancient Greek and Latin. In the chronological perusal of ancient Greek literature, it becomes evident that the various adjectives employed are often vague when looking at non-medical literature. By contrast, in the Hippocratic corpus these terms are for the first time annotated with explanations intended to lead to a more precise understanding of the described deformity. Further attempts of differentiation can be found in the writings of Galen, who not only distinguishes between outward and inward curvatures, but also between deformities of the thigh and lower leg as well as between pathological and natural curvatures. Latin literature also provides a series of adjectives that were initially often used in the meaning of 'curved' but it was not until Celsus that these were differentiated with respect to the type and direction of the curvature. When comparing Greek and Latin adjectives, it turns out that though the Latin term blaesus can be traced back etymologically to the Greek word beta lambda alpha iota sigma ó zeta, the meaning of beta lambda alpha iota sigma ó zeta does not fully correspond to that of the Latin word. It is not before the later common transliteration of Greek words that this adjective took on the meaning of beta lambda alpha iota sigma ó zeta; however, this was finally lost again. In summary, the article concludes that exact word meanings in ancient literature are often unclear and precise ascriptions of meanings are inconsistent. In the case of "curved legs," this has led to misunderstandings regarding the respective types and directions of the curvature.

  6. Correlation between stiffness and electromechanical delay components during muscle contraction and relaxation before and after static stretching.

    Science.gov (United States)

    Longo, Stefano; Cè, Emiliano; Rampichini, Susanna; Devoto, Michela; Venturelli, Massimo; Limonta, Eloisa; Esposito, Fabio

    2017-04-01

    The study was aimed at assessing possible correlations of the electromechanical delay components during muscle contraction (Delay TOT ) and relaxation (R-Delay TOT ), with muscle-tendon unit (MTU), muscle, and tendon stiffness before and after static stretching (SS). Plantarflexor muscles' maximum voluntary torque (T max ) was measured in 18 male participants (age 24±3yrs; body mass 76.4±8.9kg; stature 1.78±0.09m; mean±SD). During T max , surface electromyogram (EMG), mechanomyogram, and force signals were detected. Delay TOT and R-Delay TOT with their electrochemical and mechanical components were calculated. Passive torque and myotendinous junction displacement were assessed at 0°, 10° and 20° of dorsiflexion to determine MTU, muscle and tendon stiffness. The same protocol was repeated after SS. Delay TOT , R-Delay TOT and their mainly mechanical components correlated with MTU, muscle and tendon stiffness, both before (R 2 from 0.562 to 0.894; p<0.001) and after SS (R 2 from 0.726 to 0.955; p<0.001). SS decreased T max (-14%; p<0.001) and lengthened almost all the Delay TOT and R-Delay TOT components (from +5.9% to +30.5%; p<0.05). Correlations were found only between stiffness and the mechanical components of Delay TOT and R-Delay TOT . Correlations persisted after SS but delays increased to a higher extent than stiffness, indicating a complexity of the relationship between stiffness and delays that will be discussed in the manuscript. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Nice snake, shame about the legs.

    Science.gov (United States)

    Coates; Ruta

    2000-12-01

    Snakes are one of the most extraordinary groups of terrestrial vertebrates, with numerous specializations distinguishing them from other squamates (lizards and their allies). Their musculoskeletal system allows creeping, burrowing, swimming and even gliding, and their predatory habits are aided by chemo- and thermoreceptors, an extraordinary degree of cranial kinesis and, sometimes, powerful venoms. Recent discoveries of indisputable early fossil snakes with posterior legs are generating intense debate about the evolutionary origin of these reptiles. New cladistic analyses dispute the precise significance and phylogenetic placement of these fossils. These conflicting hypotheses imply radically different scenarios of snake origins and relationships with wide biological implications.

  8. Leg ulcer in lepromatous leprosy - Case report*

    Science.gov (United States)

    Fernandes, Tania Rita Moreno de Oliveira; dos Santos, Talita Suzany Siqueira; Lopes, Ramon Rodrigues de Macedo

    2016-01-01

    In Brazil, leprosy is a widespread infectious and contagious disease. Clinicians and specialists view leprosy broadly as a systemic infection, since, in its manifestations, it mimics many conditions, such as rheumatic, vascular, ENT, neurological and dermatological diseases. There are few studies that characterize the factors associated with ulcers in leprosy. These injuries should be prevented and treated promptly to avoid serious problems like secondary infections, sepsis, carcinomatous degeneration and amputations. We describe a patient with ulcers on his legs, involving late diagnosis of lepromatous leprosy. PMID:27828650

  9. Painful legs and moving toes syndrome

    Directory of Open Access Journals (Sweden)

    Qiu-ying Ma

    2015-10-01

    Full Text Available Painful legs and moving toes syndrome (PLMT is a rare movement disorder with low diagnostic rate, which is characterized by lower limb pain with involuntary movements of feet or toes. Etiology and pathogenesis of this disease is still unclear. Patients have different clinical manifestations, so the diagnosis is difficult. Treatment methods for PLMT are numerous, but so far the treatment of this disease is still a major challenge for clinicians. Further research is still needed to guide clinical work. DOI: 10.3969/j.issn.1672-6731.2015.10.013

  10. Comparative Analysis of the Flexural Stiffness of Pinniped Vibrissae.

    Directory of Open Access Journals (Sweden)

    Carly C Ginter Summarell

    Full Text Available Vibrissae are important components of the mammalian tactile sensory system and are used to detect vibrotactile stimuli in the environment. Pinnipeds have the largest and most highly innervated vibrissae among mammals, and the hair shafts function as a biomechanical filter spanning the environmental stimuli and the neural mechanoreceptors deep in the follicle-sinus complex. Therefore, the material properties of these structures are critical in transferring vibrotactile information to the peripheral nervous system. Vibrissae were tested as cantilever beams and their flexural stiffness (EI was measured to test the hypotheses that the shape of beaded vibrissae reduces EI and that vibrissae are anisotropic. EI was measured at two locations on each vibrissa, 25% and 50% of the overall length, and at two orientations to the point force. EI differed in orientations that were normal to each other, indicating a functional anisotropy. Since vibrissae taper from base to tip, the second moment of area (I was lower at 50% than 25% of total length. The anterior orientation exhibited greater EI values at both locations compared to the dorsal orientation for all species. Smooth vibrissae were generally stiffer than beaded vibrissae. The profiles of beaded vibrissae are known to decrease the amplitude of vibrations when protruded into a flow field. The lower EI values of beaded vibrissae, along with the reduced vibrations, may function to enhance the sensitivity of mechanoreceptors to detection of small changes in flow from swimming prey by increasing the signal to noise ratio. This study builds upon previous morphological and hydrodynamic analyses of vibrissae and is the first comparative study of the mechanical properties of pinniped vibrissae.

  11. Comparison of the noradrenergic sympathetic nerve contribution during local skin heating at forearm and leg sites in humans.

    Science.gov (United States)

    Del Pozzi, Andrew T; Hodges, Gary J

    2015-05-01

    We investigated the role of noradrenergic sympathetic nerves in the cutaneous circulation at rest and in response to local heating. Dorsal forearm and lateral leg sites were each instrumented with 2 microdialysis fibers, 2 local skin heaters, and 2 laser-Doppler probes. All sites were heated from 33° to 42 °C. Each limb had 1 skin site treated with bretylium tosylate (BT) to block noradrenergic sympathetic neurotransmitter release and 1 site infused with lactated Ringer's (Control). During baseline (33 °C), cutaneous vascular conductance (CVC; laser-Doppler flux/blood pressure) at control (24 ± 2 %max) and BT-treated (29 ± 4 %max) sites in the leg was significantly higher than the forearm (control: 12 ± 1 %max; BT-treated: 17 ± 2 %max) (P = 0.032 and P = 0.042). At 42 °C local skin temperature, the initial peak CVC response with BT decreased compared to control at both forearm (62 ± 3 vs. 86 ± 6 %max, P leg (67 ± 3 vs. 77 ± 2 %max, P = 0.035) sites. CVC at the forearm with BT was lower than that of the leg (P = 0.02). With control, plateau phase (~35 min at 42 °C) CVC was greater in the leg (98 ± 2 %max) than the forearm (89 ± 4 %max) (P = 0.027). BT reduced the peak CVC in the leg (90 ± 4 %max, P = 0.027) and in the forearm (69 ± 5 %max, P legs (P leg and forearm at rest and with skin heating.

  12. BUILDING A BETTER GLUTEAL BRIDGE: ELECTROMYOGRAPHIC ANALYSIS OF HIP MUSCLE ACTIVITY DURING MODIFIED SINGLE-LEG BRIDGES.

    Science.gov (United States)

    Lehecka, B J; Edwards, Michael; Haverkamp, Ryan; Martin, Lani; Porter, Kambry; Thach, Kailey; Sack, Richard J; Hakansson, Nils A

    2017-08-01

    Gluteal strength plays a role in injury prevention, normal gait patterns, eliminating pain, and enhancing athletic performance. Research shows high gluteal muscle activity during a single-leg bridge compared to other gluteal strengthening exercises; however, prior studies have primarily measured muscle activity with the active lower extremity starting in 90 ° of knee flexion with an extended contralateral knee. This standard position has caused reports of hamstring cramping, which may impede optimal gluteal strengthening. The purpose of this study was to determine which modified position for the single-leg bridge is best for preferentially activating the gluteus maximus and medius. Cross-Sectional. Twenty-eight healthy males and females aged 18-30 years were tested in five different, randomized single-leg bridge positions. Electromyography (EMG) electrodes were placed on subjects' gluteus maximus, gluteus medius, rectus femoris, and biceps femoris of their bridge leg (i.e., dominant or kicking leg), as well as the rectus femoris of their contralateral leg. Subjects performed a maximal voluntary isometric contraction (MVIC) for each tested muscle prior to performing five different bridge positions in randomized order. All bridge EMG data were normalized to the corresponding muscle MVIC data. A modified bridge position with the knee of the bridge leg flexed to 135 ° versus the traditional 90 ° of knee flexion demonstrated preferential activation of the gluteus maximus and gluteus medius compared to the traditional single-leg bridge. Hamstring activation significantly decreased (p bridge by flexing the active knee to 135 ° instead of 90 ° minimizes hamstring activity while maintaining high levels of gluteal activation, effectively building a bridge better suited for preferential gluteal activation. 3.

  13. Restless Legs Syndrome After Single Low Dose Quetiapine Administration.

    Science.gov (United States)

    Soyata, Ahmet Z; Celebi, Fahri; Yargc, Lutfi I

    2016-01-01

    Restless legs syndrome is an underdiagnosed sensori-motor disorder and psychotropic drugs are one of the main secondary causes of the illness. The most common psychotropic agents that cause restless legs syndrome are antidepressants; however, antipsychotics have also been reported to induce restless legs syndrome. The prevalence, vulnerability factors and the underlying mechanism of antipsychotic-induced restless legs syndrome are unclear. A possible explanation is that dopaminergic blockade is the main precipitator of the syndrome. Quetiapine-induced restless legs syndrome is another point of interest because of its low binding to D2 receptors. We herein report the case of a restless legs syndrome that emerged after a single low dose quetiapine administration.

  14. Immediate Effect of Positioning Devices on Infant Leg Movement Characteristics.

    Science.gov (United States)

    Jiang, Crystal; de Armendi, Joyce T; Smith, Beth A

    2016-01-01

    To determine the immediate effects of constraining or encouraging positioning devices on leg movement of infants with typical development (TD) and at-risk for developmental delay (AR). Twenty-six infants (13 TD, 13 AR) were placed in the supine position, a jungle gym, or a car seat. Movement sensors on infants' ankles measured acceleration and angular velocity. We calculated the number of leg movements, peak acceleration, and peak rotational rate of each leg movement. A 2 (group) × 3 (condition) analysis of variance with repeated measures on condition tested for a group effect, a condition effect, and a group by condition interaction for leg movement quantity, average peak acceleration, and average peak rotation. Leg movement quantity and average peak acceleration were significantly lower for the car seat condition compared with the supine position or the gym. Positioning device use has an immediate effect on infant leg movement characteristics. Long-term effects remain unknown.

  15. Leg Movement Activity during Sleep in School-Age Children and Adolescents: A Detailed Study in Normal Controls and Subjects with Restless Legs Syndrome and Narcolepsy Type 1.

    Science.gov (United States)

    Ferri, Raffaele; DelRosso, Lourdes M; Aricò, Debora; Zucconi, Marco; Ferini-Strambi, Luigi; Picchietti, Daniel L; Pizza, Fabio; Plazzi, Giuseppe; Manconi, Mauro; Bruni, Oliviero

    2018-01-22

    To evaluate leg movement activity during sleep (LMS) in normal school-age children and adolescents, to eventually establish age-specific periodic LMS (PLMS) index thresholds that support the diagnosis of restless legs syndrome (RLS) and to evaluate the utility of other LMS indices. Polysomnographic recordings from 61 controls, 46 children with RLS, and 44 children with narcolepsy type 1 (NT1) were analyzed for total leg movements (LMS), PLMS, and isolated leg movements (ISOLMS) duration and indices, separately for school-age children and adolescents. Moreover, intermovement interval (IMI) graphs and time-of-night distribution of LMS were analyzed and cut-off thresholds for PLMS index and total LMS index were assessed for the separation of RLS from controls. All indices tended to decrease from school-age children to adolescents in normal controls and in NT1, while in RLS, only PLMS index increased. All school-age children had a similar IMI distribution with a single peak at IMI 2-4s followed by gradual decline. In adolescents with RLS a second peak at IMI 10-50s, was seen. Time-of-night distribution of most indices decreased in RLS while most tended to increase in NT1. A PLMS index cutoff of 2/h best differentiated RLS from controls in school-age children (accuracy 70.0%) and in adolescents (accuracy 70.8%); however, most NT1 subjects also showed PLMS indices higher than this threshold. PLMS index alone does not reliably predict the diagnosis of RLS in children and adolescents. However, analyses of IMI distribution and time-of-night distribution provide additional elements to support a diagnosis of RLS. © Sleep Research Society 2018. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  16. Stiffness of endodontically-treated teeth related to restoration technique.

    Science.gov (United States)

    Reeh, E S; Douglas, W H; Messer, H H

    1989-11-01

    Endodontically-treated posterior teeth are susceptible to fracture; consequently, full-occlusal-coverage restorations are recommended. We designed this study to examine the potential for alternative restorative techniques for pulpless teeth, using strain gauges mounted on extracted maxillary second premolars to measure strains generated by nondestructive occlusal loading. Cuspal stiffness was evaluated on the following sequentially performed procedures: unaltered tooth, completion of all endodontic procedures, appropriate restorative preparation, and restoration. The restorative procedures evaluated were: (1) amalgam, (2) cast gold onlay, (3) composite restoration with enamel etch, and (4) composite restoration with enamel and dentin etch. Finally, all teeth were loaded to fracture. Cast gold was the strongest restorative material tested (2.11 relative stiffness, compared with that of the unaltered tooth at 1.00), and amalgam was the weakest (0.35 relative stiffness). Composite restoration and enamel plus dentin etch were almost as strong as the unaltered tooth (0.87 relative stiffness), while enamel-etch-only yielded lower stiffness (0.51).

  17. Modelling, simulation and experiment of the spherical flexible joint stiffness

    Directory of Open Access Journals (Sweden)

    S. Li

    2018-02-01

    Full Text Available The spherical flexible joint is extensively used in engineering. It is designed to provide flexibility in rotation while bearing vertical compression load. The linear rotational stiffness of the flexible joint is formulated. The rotational stiffness of the bonded rubber layer is related to inner radius, thickness and two edge angles. FEM is used to verify the analytical solution and analyze the stiffness. The Mooney–Rivlin, Neo Hooke and Yeoh constitutive models are used in the simulation. The experiment is taken to obtain the material coefficient and validate the analytical and FEM results. The Yeoh model can reflect the deformation trend more accurately, but the error in the nearly linear district is bigger than the Mooney–Rivlin model. The Mooney–Rivlin model can fit the test result very well and the analytical solution can also be used when the rubber deformation in the flexible joint is small. The increase of Poisson's ratio of the rubber layers will enhance the vertical compression stiffness but barely have effect on the rotational stiffness.

  18. Dynamically tuned magnetostrictive spring with electrically controlled stiffness

    Science.gov (United States)

    Scheidler, Justin J.; Asnani, Vivake M.; Dapino, Marcelo J.

    2016-03-01

    This paper presents the design and testing of an electrically controllable magnetostrictive spring that has a dynamically tunable stiffness (i.e., a magnetostrictive Varispring). The device enables in situ stiffness tuning or stiffness switching for vibration control applications. Using a nonlinear electromechanical transducer model and an analytical solution of linear, mechanically induced magnetic diffusion, Terfenol-D is shown to have a faster rise time to stepped voltage inputs and a significantly higher magnetic diffusion cut-off frequency relative to Galfenol. A Varispring is manufactured using a laminated Terfenol-D rod. Further rise time reductions are achieved by minimizing the rod’s diameter and winding the electromagnet with larger wire. Dynamic tuning of the Varispring’s stiffness is investigated by measuring the Terfenol-D rod’s strain response to dynamic, compressive, axial forces in the presence of sinusoidal or square wave control currents. The Varispring’s rise time is \\lt 1 ms for 1 A current switches. Continuous modulus changes up to 21.9 GPa and 500 Hz and square wave modulus changes (dynamic {{Δ }}E effect) up to 12.3 GPa and 100 Hz are observed. Stiffness tunability and tuning bandwidth can be considerably increased by operating about a more optimal bias stress and improving the control of the electrical input.

  19. Instantaneous stiffness and hysteresis of dynamic elastic response prosthetic feet.

    Science.gov (United States)

    Webber, Christina M; Kaufman, Kenton

    2017-10-01

    Dynamic elastic response prosthetic feet are designed to mimic the functional characteristics of the native foot/ankle joint. Numerous designs of dynamic elastic response feet exist which make the prescription process difficult, especially because of the lack of empirical evidence describing the objective performance characteristics of the feet. To quantify the mechanical properties of available dynamic elastic response prosthetic feet, specifically the stiffness and hysteresis. Mechanical testing of dynamic elastic response prosthetic feet. Static Proof Testing in accordance with ISO 10328 was conducted on seven dynamic elastic response prosthetic feet. Load-displacement data were used to calculate the instantaneous stiffness in both the heel and forefoot regions, as well as hysteresis associated with each foot. Heel stiffness was greater than forefoot stiffness for all feet. The heel of the glass composite prosthetic foot was stiffer than the carbon fiber feet and it exhibited less hysteresis. Two different carbon fiber feet had the stiffest forefoot regions. Mechanical testing is a reproducible method that can be used to provide objective evidence about dynamic elastic response prosthetic foot performance and aid in the prescription process. Clinical relevance The quantitative stiffness and hysteresis data from this study can be used by prosthetists to aid the prescription process and make it more objective.

  20. Leg Length Versus Torso Length in Pedophilia: Further Evidence of Atypical Physical Development Early in Life.

    Science.gov (United States)

    Fazio, Rachel L; Dyshniku, Fiona; Lykins, Amy D; Cantor, James M

    2017-08-01

    Adult men's height results from an interaction among positive and negative influences, including genetic predisposition, conditions in utero, and influences during early development such as nutritional quality, pathogen exposure, and socioeconomic status. Decreased height, reflected specifically as a decreased leg length, is strongly associated with increased risk of poorer health outcomes. Although prior research has repeatedly shown that pedophiles are shorter than nonpedophiles, the largest study to date relied on self-reported height. In the present study, pedophiles demonstrated reduced measured height and reduced leg length as compared with teleiophiles. Given the prenatal and early childhood origins of height, these findings contribute additional evidence to a biological, developmental origin of pedophilia. In addition, the magnitude of this height difference was substantially larger than that found in children exposed to a variety of early environmental stressors, but similar to that seen in other biologically based neurodevelopmental disorders.

  1. Nocturnal leg cramps in children: incidence and clinical characteristics.

    Science.gov (United States)

    Leung, A. K.; Wong, B. E.; Chan, P. Y.; Cho, H. Y.

    1999-01-01

    The records of 2527 healthy children seen in an ambulatory care clinic were evaluated for nocturnal leg cramps in the preceding 12 months, frequency and duration of the cramps, whether the cramps affected one leg or both legs at a time, whether there was associated muscle cramps in feet, whether the cramps occurred when the child was awake or asleep, and whether there was residual tenderness in the affected muscles. Nocturnal leg cramps were present in 185 children for an overall incidence of 7.3%. Leg cramps were noted only in children aged > or = 8 years. The incidence increased at 12 years and peaked at 16 to 18 years of age. A majority (81.6%) of the affected children had nocturnal leg cramps 1 to 4 times per year. The mean duration of episodes was 1.7 minutes. Leg cramps were unilateral in 98.9% of cases and the ipsilateral foot also was involved in 18.9% of cases. One hundred thirty-five (73%) children had leg cramps while asleep, and the remaining 23 (12.4%) children had leg cramps in either state. Fifty-seven (30.8%) children had residual tenderness in the affected muscles. The mean duration of residual tenderness was 33.2 minutes (range: 2 minutes-1 day). We conclude that nocturnal leg cramps are common in children aged > 12 years. A majority of the affected children have leg cramps 1 to 4 times per year. The cramps are usually unilateral and occur when the children are asleep. Normal duration of the leg cramp is < 2 minutes. Residual tenderness is present in approximately 30% of the affected children. Residual tenderness, if present, usually lasts for half an hour. PMID:10388258

  2. Six weeks' aerobic retraining after two weeks' immobilization restores leg lean mass and aerobic capacity but does not fully rehabilitate leg strenght in young and older men

    DEFF Research Database (Denmark)

    Vigelsø Hansen, Andreas; Gram, Martin; Wiuff, Caroline

    2015-01-01

    OBJECTIVE: To determine the effect of aerobic retraining as rehabilitation after short-term leg immobilization on leg strength, leg work capacity, leg lean mass, leg muscle fibre type composition and leg capillary supply, in young and older men. SUBJECTS AND DESIGN: Seventeen young (23 ± 1 years...... immobilization had marked effects on leg strength, and work capacity and 6 weeks' retraining was sufficient to increase, but not completely rehabilitate, muscle strength, and to rehabilitate aerobic work capacity and leg lean mass (in the young men)....

  3. The study of dynamic force acted on water strider leg departing from water surface

    Directory of Open Access Journals (Sweden)

    Peiyuan Sun

    2018-01-01

    Full Text Available Water-walking insects such as water striders can skate on the water surface easily with the help of the hierarchical structure on legs. Numerous theoretical and experimental studies show that the hierarchical structure would help water strider in quasi-static case such as load-bearing capacity. However, the advantage of the hierarchical structure in the dynamic stage has not been reported yet. In this paper, the function of super hydrophobicity and the hierarchical structure was investigated by measuring the adhesion force of legs departing from the water surface at different lifting speed by a dynamic force sensor. The results show that the adhesion force decreased with the increase of lifting speed from 0.02 m/s to 0.4 m/s, whose mechanic is investigated by Energy analysis. In addition, it can be found that the needle shape setae on water strider leg can help them depart from water surface easily. Thus, it can serve as a starting point to understand how the hierarchical structure on the legs help water-walking insects to jump upward rapidly to avoid preying by other insects.

  4. The study of dynamic force acted on water strider leg departing from water surface

    Science.gov (United States)

    Sun, Peiyuan; Zhao, Meirong; Jiang, Jile; Zheng, Yelong

    2018-01-01

    Water-walking insects such as water striders can skate on the water surface easily with the help of the hierarchical structure on legs. Numerous theoretical and experimental studies show that the hierarchical structure would help water strider in quasi-static case such as load-bearing capacity. However, the advantage of the hierarchical structure in the dynamic stage has not been reported yet. In this paper, the function of super hydrophobicity and the hierarchical structure was investigated by measuring the adhesion force of legs departing from the water surface at different lifting speed by a dynamic force sensor. The results show that the adhesion force decreased with the increase of lifting speed from 0.02 m/s to 0.4 m/s, whose mechanic is investigated by Energy analysis. In addition, it can be found that the needle shape setae on water strider leg can help them depart from water surface easily. Thus, it can serve as a starting point to understand how the hierarchical structure on the legs help water-walking insects to jump upward rapidly to avoid preying by other insects.

  5. An Ultralightweight and Living Legged Robot.

    Science.gov (United States)

    Vo Doan, Tat Thang; Tan, Melvin Y W; Bui, Xuan Hien; Sato, Hirotaka

    2018-02-01

    In this study, we describe the most ultralightweight living legged robot to date that makes it a strong candidate for a search and rescue mission. The robot is a living beetle with a wireless electronic backpack stimulator mounted on its thorax. Inheriting from the living insect, the robot employs a compliant body made of soft actuators, rigid exoskeletons, and flexure hinges. Such structure would allow the robot to easily adapt to any complex terrain due to the benefit of soft interface, self-balance, and self-adaptation of the insect without any complex controller. The antenna stimulation enables the robot to perform not only left/right turning but also backward walking and even cessation of walking. We were also able to grade the turning and backward walking speeds by changing the stimulation frequency. The power required to drive the robot is low as the power consumption of the antenna stimulation is in the order of hundreds of microwatts. In contrast to the traditional legged robots, this robot is of low cost, easy to construct, simple to control, and has ultralow power consumption.

  6. Acute effects of acupuncture treatment with Baihui (GV20) on human arterial stiffness and wave reflection.

    Science.gov (United States)

    Satoh, Hiroyasu

    2009-06-01

    Treatment by manual acupuncture needling affects the vascular wall tone, and hemodynamic parameters for arterial stiffness may be characterized by treatment at the traditional acupuncture point (acupoint) of Baihui (GV20). The acute effects of acupuncture treatment on arterial stiffness and wave reflection were investigated and, simultaneously, an augmentation index (AI), as an index of wave reflection, was estimated. These parameters were measured in male volunteers using applanation tonometry during 20 minutes of acupuncture treatment and 40 minutes post-acupuncture. During treatment, diastolic blood pressure (BP), but not systolic BP, increased significantly. Heart rates (HR) initially tended to increase and then decrease. The AI from radial arteries increased significantly, while central aortic blood pressure (CBP) was unaffected. Post-acupuncture, the effects lasted for 30-40 minutes. The average BP and HR were +10.1+/-0.3% and -7.2+/-0.2%, respectively, and the CBPs were not altered, but the AI decreased markedly; this latter effect presumably resulted from the involvement of neurovascular modulators. These results indicated that acute treatment at Baihui enhanced arteriosclerotic parameters. In post-acupuncture, the AI profoundly decreased, presumably resulting from the involvement with neurovascular modulators.

  7. Leg Rejuvenation: A Combination Approach: A Review and Our Experience.

    Science.gov (United States)

    Weiss, Margaret; Mahoney, Anne M; Gold, Michael; Lawrence, Naomi

    2016-05-01

    Patients increasingly seek to enhance the appearance of their legs. Elimination of unwanted leg veins, reduction of epidermal photo-aging changes such as solar lentigines and keratoses, tightening of skin laxity and reduction of adipose tissue are among the most commonly requested goals. Many patients require a combination approach to address their concerns. It is important for dermatologists to be aware of the multitude of procedures that can be performed, often in combination, to rejuvenate the leg. The purpose of this review article was to discuss procedures for improving the appearance of the leg and to share the authors experience, especially in the combination approach to leg rejuvenation. A literature search was performed to investigate cosmetic procedures being performed on the leg, with an emphasis on controlled or randomized studies. In addition, the authors contributed their personal experience. Our discussion of the literature review highlights the treatments for leg veins, unwanted fat, cellulite, and photodamage of the legs that are most supported in peer-reviewed publications. A synergistic, combination approach to leg rejuvenation works best. This includes the use of injectable agents, energy-based devices, and more invasive surgical procedures.

  8. An Integrated Approach to Single-Leg Airline Revenue Management: The Role of Robust Optimization

    OpenAIRE

    Birbil, Ilker; Frenk, Hans; Gromicho, Joaquim; Zhang, Shuzhong

    2006-01-01

    textabstractIn this paper we introduce robust versions of the classical static and dynamic single leg seat allocation models as analyzed by Wollmer, and Lautenbacher and Stidham, respectively. These robust models take into account the inaccurate estimates of the underlying probability distributions. As observed by simulation experiments it turns out that for these robust versions the variability compared to their classical counter parts is considerably reduced with a negligible decrease of av...

  9. Bone and soft tissue components of the leg in infants with protein calorie malnutrition

    Energy Technology Data Exchange (ETDEWEB)

    Akamaguna, A.I.; Odita, J.C.; Ugbodaga, C.I.; Okolo, A.A.

    1986-01-01

    The measurements of muscle, fat and cortical thickness were made on leg radiographs of 40 kwashiorkhor infants and were compared with those of 32 normal infants. There is a significant decrease in muscle cylinder ratio, an index of the contribution of muscle to calf thickness in kwashiorkhor. The loss of bone cortex in kwashiorkhor is due mainly to failure of appositional growth. The muscle cylinder ratio in normal Nigerian infants in much higher than has been reported amongst Caucasians. (orig.).

  10. Bone and soft tissue components of the leg in infants with protein calorie malnutrition

    International Nuclear Information System (INIS)

    Akamaguna, A.I.; Odita, J.C.; Ugbodaga, C.I.; Okolo, A.A.

    1986-01-01

    The measurements of muscle, fat and cortical thickness were made on leg radiographs of 40 kwashiorkhor infants and were compared with those of 32 normal infants. There is a significant decrease in muscle cylinder ratio, an index of the contribution of muscle to calf thickness in kwashiorkhor. The loss of bone cortex in kwashiorkhor is due mainly to failure of appositional growth. The muscle cylinder ratio in normal Nigerian infants in much higher than has been reported amongst Caucasians. (orig.)

  11. Axial Dynamic Stiffness of Tubular Piles in Viscoelastic Soil

    DEFF Research Database (Denmark)

    Bayat, Mehdi; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    2016-01-01

    Large offshore wind turbines are f0W1ded on jacket structures. In this study, an elastic full-space jacket structure foundation in an elastic and viscoelastic medium is investigated by using boundary integral equations. The jacket structure foundation is modeled as a hollow, long circular cylinder......-resonance are presented .in series of Bessel's function. Important responses, such as dynamic stiffness and phase angle, are compared for different values of the loss factor as the material damping, Y0W1g's modulus and Poisson's ratio in a viscoelastic soil. Results are verified. with known results reported...... in the literature. It is observed that the dynamic stiffness fluctuates with the loss factor, and the turning point is independent of the loss factor while the turning point increases with load frequency. It is seen that the non-dimensional dynamic stiffness is dependent on Young's modulus and Poisson's ratio...

  12. Output-Based Control of Robots with Variable Stiffness Actuation

    Directory of Open Access Journals (Sweden)

    Gianluca Palli

    2011-01-01

    Full Text Available The output-based control of a redundant robotic manipulator with relevant and adjustable joint stiffness is addressed. The proposed controller is configured as a cascade system that allows the decoupling of the actuators dynamics from the arm dynamics and the consequent reduction of the order of the manipulator dynamic model. Moreover, the proposed controller does not require the knowledge of the whole robot state: only the positions of the actuators and of the joints are necessary. This approach represents a significant simplification with respect to previously proposed state feedback techniques. The problem of controlling simultaneously the position trajectory and the desired stiffness in both the joint and work space is investigated, and the relations between the manipulator redundancy and the selection of both the joint and work space stiffness of the manipulator are discussed. The effectiveness of the proposed approach is verified by simulations of a 3 degrees of freedom planar manipulator.

  13. Polymer hydration and stiffness at biointerfaces and related cellular processes.

    Science.gov (United States)

    Kerch, Garry

    2018-01-01

    The direct and indirect (by changing mechanical properties) effects of hydration at interfaces on cellular processes and tissue diseases are reviewed. The essential effect of substrate stiffness on cellular processes was demonstrated in the last decade. The combined effect of surface stiffness and hydration at interfaces has garnered much less attention, though hydration and dehydration play important roles in biological processes. This review focuses on the studies that demonstrate how hydration affects biological processes at interfaces. Elevated sodium and dehydration stimulate inflammatory signaling in endothelial cells and promote atherosclerosis. Various types of implant and blood contacting device coatings with varied surface stiffness and hydration have been reported. Effect of hydration on polymer modulus of elasticity and viscoelasticity was discussed taking into account cells adhesion, migration, proliferation, differentiation on surfaces with various degree of hydration. Future directions of research were considered, including the use of nanotechnology to regulate the hydration degree. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Large variation finite element method for beams with stochastic stiffness

    CERN Document Server

    Rollot, O

    2003-01-01

    The behavior of beams with stochastic stiffness subjected to either deterministic or stochastic loading is studied via finite element method. The results are contrasted with exact solution to check the accuracy of the FEM for the case of large variations. It represents a generalization of the previous study in which the stiffness matrix was decomposed as a product of three matrices, two of which are numerical ones and the third matrix involves the uncertain stiffness analytically. To illustrate the proposed method, we evaluate the mean and the auto-correlation functions of the displacement of beams under various boundary conditions. Two statically determinate beams (clamped-free or simply-supported) and two statically indeterminate beams (clamped-simply-supported or clamped are both ends) are investigated in this study. The beams are subjected to a deterministic uniform pressure or a stochastic excitation.

  15. Mixed, Nonsplit, Extended Stability, Stiff Integration of Reaction Diffusion Equations

    KAUST Repository

    Alzahrani, Hasnaa H.

    2016-07-26

    A tailored integration scheme is developed to treat stiff reaction-diffusion prob- lems. The construction adapts a stiff solver, namely VODE, to treat reaction im- plicitly together with explicit treatment of diffusion. The second-order Runge-Kutta- Chebyshev (RKC) scheme is adjusted to integrate diffusion. Spatial operator is de- scretised by second-order finite differences on a uniform grid. The overall solution is advanced over S fractional stiff integrations, where S corresponds to the number of RKC stages. The behavior of the scheme is analyzed by applying it to three simple problems. The results show that it achieves second-order accuracy, thus, preserving the formal accuracy of the original RKC. The presented development sets the stage for future extensions, particularly, to multidimensional reacting flows with detailed chemistry.

  16. Large variation finite element method for beams with stochastic stiffness

    International Nuclear Information System (INIS)

    Rollot, Olivier; Elishakoff, Isaac

    2003-01-01

    The behavior of beams with stochastic stiffness subjected to either deterministic or stochastic loading is studied via finite element method. The results are contrasted with exact solution to check the accuracy of the FEM for the case of large variations. It represents a generalization of the previous study in which the stiffness matrix was decomposed as a product of three matrices, two of which are numerical ones and the third matrix involves the uncertain stiffness analytically. To illustrate the proposed method, we evaluate the mean and the auto-correlation functions of the displacement of beams under various boundary conditions. Two statically determinate beams (clamped-free or simply-supported) and two statically indeterminate beams (clamped-simply-supported or clamped are both ends) are investigated in this study. The beams are subjected to a deterministic uniform pressure or a stochastic excitation

  17. Design of Stiffness for Air Spring Based on ABAQUS

    Directory of Open Access Journals (Sweden)

    Hongguang Li

    2013-01-01

    Full Text Available In this paper, an axisymmetric finite element (FE model of an air spring was carried out with the software ABAQUS to design its target vertical stiffness. The bellows was simulated by the reinforced surface element. The compressed gas in the cavity of the air spring was represented by the hydrostatic fluid element. The target stiffness is obtained by modifying the valid area of the cross section. At last, the results of experiment coincided well with the simulation data. The study shows that the static stiffness of air spring is sensitive to the effective area of the cross section. The conclusion has certain practical significance for the design and the optimization of the same kind of air spring.

  18. Analytical study of a quasi-zero stiffness coupling using a torsion magnetic spring with negative stiffness

    Science.gov (United States)

    Zheng, Yisheng; Zhang, Xinong; Luo, Yajun; Zhang, Yahong; Xie, Shilin

    2018-02-01

    By now, many translation quasi-zero stiffness (QZS) mechanisms have been proposed to overcome the restriction between the isolation frequency range and the load bearing capacity of linear isolators. The couplings of rotor systems undertake the functions of transmitting static driving torque and isolating disturbing torque simultaneously, which creates the demand of torsion QZS mechanisms. Hence a QZS coupling is presented in this paper, where a torsion magnetic spring (TMS) composed of two coaxial ring magnet arrangements in repulsive configuration is employed to produce negative torsion stiffness to counteract the positive stiffness of a rubber spring. In this paper, the expressions of magnetic torque and stiffness are given firstly and verified by finite element simulations; and the effect of geometric parameters of the TMS on its stiffness characteristic is analyzed in detail, which contributes to the optimal design of the TMS. Then dynamic analysis of the QZS coupling is performed and the analytical expression of the torque transmissibility is achieved based on the Harmonic Balance Method. Finally, simulation of the torque transmissibility is carried out to reveal how geometric parameters of the TMS affect the isolation performance.

  19. Aerobic exercise training-induced changes in serum adropin level are associated with reduced arterial stiffness in middle-aged and older adults.

    Science.gov (United States)

    Fujie, Shumpei; Hasegawa, Natsuki; Sato, Koji; Fujita, Satoshi; Sanada, Kiyoshi; Hamaoka, Takafumi; Iemitsu, Motoyuki

    2015-11-15

    Aging-induced arterial stiffening is reduced by aerobic exercise training, and elevated production of nitric oxide (NO) participates in this effect. Adropin is a regulator of endothelial NO synthase and NO release, and circulating adropin level decreases with age. However, the effect of habitual aerobic exercise on circulating adropin levels in healthy middle-aged and older adults remains unclear. We sought to determine whether serum adropin level is associated with exercise training-induced changes in arterial stiffness. First, in a cross-sectional study, we investigated the association between serum adropin level and both arterial stiffness and cardiorespiratory fitness in 80 healthy middle-aged and older subjects (65.6 ± 0.9 yr). Second, in an intervention study, we examined the effects of 8-wk aerobic exercise training on serum adropin level and arterial stiffness in 40 healthy middle-aged and older subjects (67.3 ± 1.0 yr) divided into two groups: aerobic exercise training and sedentary controls. In the cross-sectional study, serum adropin level was negatively correlated with carotid β-stiffness (r = -0.437, P aerobic exercise training intervention, and training-induced changes in serum adropin level were correlated with training-induced changes in carotid β-stiffness (r = -0.399, P exercise-induced reduction of arterial stiffness. Copyright © 2015 the American Physiological Society.

  20. Pathological and radiological investigations on osteochondrosis in pigs, associated with leg weakness

    International Nuclear Information System (INIS)

    Jørgensen, B.; Arnbjerg, J.; Aaslyng, M.

    1995-01-01

    Two-hundred and seventy-eight Danish Landrace boars were examined radiologically and pathologically for osteochondrosis and other joint lesions on the left legs at slaughter (95 kg). The joint changes were scored on a scale from 1 (normal) to 5 (very severe changes/osteochondritis dissecans). The correlations between radiological and pathological scores were highly significant in the humeral condyles (r = 0.66, P lt 0.001), the distal ulna growth plate (r = 0.51, P lt 0.001), the femoral condyles (r = 0.33, P lt 0.001) and hock (distal tibia (r = 0.17, P lt 0.01) and the medial trochlear ridge of the talus (r = 0.17, P lt 0.01), indicating that radiographical examination is a useful method for diagnosing osteochondrosis in live pigs. Thickening of cartilage was strongly associated with subchondral lesions in the three predilection sites: the humeral condyle, the femoral condyles and the distal ulna growth plate. Osteochondritis dissecans (OCD) in the humeral condyles was significantly associated with subchondral lesions (OR= 1.86; P lt 0.001), but not with cartilage thickness when analysed simultaneously. There were no associations between lesions in the distal ulna growth place, the humeral condyles, the femoral condyles or the anconeal process. There was no significant correlation' between OCD in the humeral condyles and the anconeal process. Osteochondrosis could therefore not be stated to be a generalized disorder. Regression coefficients between joint changes and leg weakness symptoms judged before slaughter were very small and showed no clear trends. OCD in the humeral condyles was, however, significantly associated with 'legs turned out on fore (OR = 2.48; P lt 0.001) and hind (OR = 1.62; P lt 0.05) legs', and OCD in the anconeal process with 'stiff movement in front' (OH+OR = 2.01; P lt 0.05). Osteochondrosis is thus comparable with a threshold trait, where the threshold is the development of an OCD in an osteochondrosis injured joint