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Sample records for motor conduction velocity

  1. Motor Nerve Conduction Velocity In Postmenopausal Women with Peripheral Neuropathy

    PubMed Central

    Asif, Naiyer; Singh, Paras Nath; Hossain, Mohd Mobarak

    2016-01-01

    Introduction The post-menopausal phase is characterized by a decline in the serum oestrogen and progesterone levels. This phase is also associated with higher incidence of peripheral neuropathy. Aim To explore the relationship between the peripheral motor nerve status and serum oestrogen and progesterone levels through assessment of Motor Nerve Conduction Velocity (MNCV) in post-menopausal women with peripheral neuropathy. Materials and Methods This cross-sectional study was conducted at Jawaharlal Nehru Medical College during 2011-2013. The study included 30 post-menopausal women with peripheral neuropathy (age: 51.4±7.9) and 30 post-menopausal women without peripheral neuropathy (control) (age: 52.5±4.9). They were compared for MNCV in median, ulnar and common peroneal nerves and serum levels of oestrogen and progesterone estimated through enzyme immunoassays. To study the relationship between hormone levels and MNCV, a stepwise linear regression analysis was done. Results The post-menopausal women with peripheral neuropathy had significantly lower MNCV and serum oestrogen and progesterone levels as compared to control subjects. Stepwise linear regression analysis showed oestrogen with main effect on MNCV. Conclusion The findings of the present study suggest that while the post-menopausal age group is at a greater risk of peripheral neuropathy, it is the decline in the serum estrogen levels which is critical in the development of peripheral neuropathy. PMID:28208850

  2. Assessment of temporal dispersion in motor nerves with normal conduction velocity.

    PubMed

    Schulte-Mattler, W J; Jakob, M; Zierz, S

    1999-04-01

    Demyelinated nerves attenuate high-frequency components of propagating action potentials. In order to study if there is diagnostic use of this in motor nerves, the spectral energy above 49 Hz, amplitude, area, and duration of the compound muscle action potentials were measured; values after distal and proximal stimulation of posterior tibial nerves were compared. Normative data were collected in 48 control subjects. The same measurements were made in 20 patients with polyneuropathy and reduced motor nerve conduction velocity, in 21 patients with mild polyneuropathy but normal motor nerve conduction velocity, and in 8 patients with myasthenia gravis. Overall, high-frequency attenuation was closely correlated with amplitude decay (r = 0.63, P<10(-19)) and with increase of action potential duration (r = 0.34, P = 10(-5)). In the group of patients with normal NCV, high-frequency attenuation was abnormal in 9 (43%), amplitude decay was abnormal in two (10%), and area decay was abnormal in one (5%) patient. The action potential duration was normal in all of these patients. High-frequency attenuation was not influenced by stimulus intensity, thus it is not changed by conduction block, and it was not influenced by impaired neuromuscular transmission. Hence, high-frequency attenuation, both sensitively and specifically does indicate abnormal temporal dispersion. In conclusion, the simple measurement of high-frequency attenuation markedly improves detection and characterization of demyelination of human motor fibers.

  3. Motor unit action potential conduction velocity estimated from surface electromyographic signals using image processing techniques.

    PubMed

    Soares, Fabiano Araujo; Carvalho, João Luiz Azevedo; Miosso, Cristiano Jacques; de Andrade, Marcelino Monteiro; da Rocha, Adson Ferreira

    2015-09-17

    In surface electromyography (surface EMG, or S-EMG), conduction velocity (CV) refers to the velocity at which the motor unit action potentials (MUAPs) propagate along the muscle fibers, during contractions. The CV is related to the type and diameter of the muscle fibers, ion concentration, pH, and firing rate of the motor units (MUs). The CV can be used in the evaluation of contractile properties of MUs, and of muscle fatigue. The most popular methods for CV estimation are those based on maximum likelihood estimation (MLE). This work proposes an algorithm for estimating CV from S-EMG signals, using digital image processing techniques. The proposed approach is demonstrated and evaluated, using both simulated and experimentally-acquired multichannel S-EMG signals. We show that the proposed algorithm is as precise and accurate as the MLE method in typical conditions of noise and CV. The proposed method is not susceptible to errors associated with MUAP propagation direction or inadequate initialization parameters, which are common with the MLE algorithm. Image processing -based approaches may be useful in S-EMG analysis to extract different physiological parameters from multichannel S-EMG signals. Other new methods based on image processing could also be developed to help solving other tasks in EMG analysis, such as estimation of the CV for individual MUs, localization and tracking of innervation zones, and study of MU recruitment strategies.

  4. Motor Nerve Conduction Velocity Depends on Stimuli Frequency in the Rat

    NASA Astrophysics Data System (ADS)

    Méndez, Ma C.; Cruz, Elizabeth; Caudillo, Cipriana; Sosa, Modesto; Gamiño, Sergio M.

    2003-09-01

    This study was performed to evaluate the effect of frequency and duration of stimuli on motor nerve conduction velocity (MNCV) in the rat. MNCV was evaluated in two separate series of records. In the first the frequency of stimuli was varied between 1.0 and 10.0 Hz, by 1 Hz steps, keeping the duration of the pulses constant at 0.1 ms. In a second experimental trial, the frequency of the stimuli was kept at 10.0 Hz, while duration increased from 0.05 to 1.00 ms, at customized steps. Supramaximal stimulation pulses were always used. Measures were performed in the right pelvic limb of 12 anesthetized rats. The active needle electrode was inserted in the second interosseus space of the paw, while a subcutaneous reference electrode was inserted in the third toe. The ground electrode was placed on dorsal surface of the limb. The proximal stimuli site was identified at the sciatic notch and the distal one at the ankle. Surface stimulation was used. Latency, duration, area under the curve and amplitude of the muscular action potential were also measured. MNCV was estimated by dividing distal to proximal latency difference by the distance between stimuli sites. MNCV exhibited an increase to a plateu with stimulus frequency growth. Duration also showed the same behavior.

  5. A method of monitoring function in corticospinal pathways during scoliosis surgery with a note on motor conduction velocities.

    PubMed Central

    Boyd, S G; Rothwell, J C; Cowan, J M; Webb, P J; Morley, T; Asselman, P; Marsden, C D

    1986-01-01

    Spinal cord potentials produced by high voltage electrical stimulation of the scalp over the motor cortex were recorded intraoperatively from bipolar electrodes inserted into the epidural space of eleven patients undergoing corrective surgery for scoliosis. Responses to single stimuli could be recorded from the cord at all levels from cervical to low thoracic regions. The potentials were larger in the cervical than in the thoracic region and sometimes were followed by later waves at high stimulation intensities. Conduction velocity in large corticomotoneuron fibres was estimated to be between 50-74 ms-1 in different patients. This technique for monitoring motor tract function may be a useful adjunct to conventional monitoring of the sensory pathways during surgery. PMID:3958738

  6. Pycnogenol efficiency on glycaemia, motor nerve conduction velocity and markers of oxidative stress in mild type diabetes in rats.

    PubMed

    Jankyova, S; Kucera, P; Goldenberg, Z; Yaghi, D; Navarova, J; Kyselova, Z; Stolc, S; Klimas, J; Racanska, E; Matyas, S

    2009-08-01

    The aim of this study was to describe the effects of Pycnogenol at various doses on preprandial and postprandial glucose levels, the levels of thiobarbituric acid reactive substances (TBARs) and N-acetyl-beta-d-glucosaminidase (NAGA) and on motor nerve conduction velocity (MNCV) in streptozotocin (STZ)-induced diabetic rats. Pycnogenol treatment (10, 20, 50 mg/kg body weight (b.w.)/day) lasted for 8 weeks after induction of diabetes. Pycnogenol significantly decreased elevated levels of preprandial glycaemia in treated animals at all doses. At doses of 10 mg/kg b.w./day and 20 mg/kg b.w./day it significantly decreased elevated levels of postprandial glycaemia compared with diabetic non-treated animals. Pycnogenol failed to induce a significant decrease of postprandial glycaemia at a dose of 50 mg/kg b.w./day. Pycnogenol improved significantly the impaired MNCV at doses of 10 and 20 mg/kg b.w./day compared with non-treated animals. The levels of TBARs were elevated in diabetic rats. The levels of NAGA increased gradually despite the treatment. Pycnogenol failed to affect the increased levels of TBARs and NAGA. Pycnogenollowered the elevated levels of glycaemia and reduced the decline in motor nerve conduction velocity in STZ-induced diabetic rats. The effect of Pycnogenol on postprandial glycaemic levels and MNCV was not dose-dependent.

  7. Effects of lead acetate on guinea pig - cochear microphonics, action potential, and motor nerve conduction velocity

    SciTech Connect

    Yamamura, K.; Maehara, N.; Terayama, K.; Ueno, N.; Kohyama, A.; Sawada, Y.; Kishi, R.

    1987-04-01

    Segmental demyelination and axonal degeneration of motor nerves induced by lead exposure is well known in man, and animals. The effect of lead acetate exposure to man may involve the cranial nerves, since vertigo and sensory neuronal deafness have been reported among lead workers. However, there are few reports concerning the dose-effects of lead acetate both to the peripheral nerve and the cranial VII nerve with measurement of blood lead concentration. The authors investigated the effects of lead acetate to the cochlea and the VIII nerve using CM (cochlear microphonics) and AP (action potential) of the guinea pigs. The effects of lead acetate to the sciatic nerve were measured by MCV of the sciatic nerve with measurement of blood lead concentration.

  8. Conduction velocity of antigravity muscle action potentials.

    PubMed

    Christova, L; Kosarov, D; Christova, P

    1992-01-01

    The conduction velocity of the impulses along the muscle fibers is one of the parameters of the extraterritorial potentials of the motor units allowing for the evaluation of the functional state of the muscles. There are no data about the conduction velocities of antigravity muscleaction potentials. In this paper we offer a method for measuring conduction velocity of potentials of single MUs and the averaged potentials of the interference electromiogram (IEMG) lead-off by surface electrodes from mm. sternocleidomastoideus, trapezius, deltoideus (caput laterale) and vastus medialis. The measured mean values of the conduction velocity of antigravity muscles potentials can be used for testing the functional state of the muscles.

  9. A Simulation Study to Investigate the Sensitivity of the Electromyogram to Conduction Velocity Changes of Individual Motor Units

    DTIC Science & Technology

    2001-10-25

    C . Signal Analysis The most popular frequency analysis method used on EMG’s, is the Fourier Transform. One issue arising with its use is...applied ischemia,” Eur. J. Appl. Physiol., vol.56, pp.212-216, 1987. [6] R. Merletti, M. Knaflitz and C . De Luca, “Myoelectric manifestations of...conduction velocity,” IEEE Trans. Rehab. Eng., vol.8, no.3, pp.353-361, Sept. 2000. [10 ] E. Henneman , G. Somjen and D. Carpenter, “Excitability and

  10. Tuning Multiple Motor Travel Via Single Motor Velocity

    PubMed Central

    Xu, Jing; Shu, Zhanyong; King, Stephen J.; Gross, Steven P.

    2012-01-01

    Microtubule-based molecular motors often work in small groups to transport cargos in cells. A key question in understanding transport (and its regulation in vivo) is to identify the sensitivity of multiple-motor-based motion to various single molecule properties. Whereas both single-motor travel distance and microtubule binding rate have been demonstrated to contribute to cargo travel, the role of single-motor velocity is yet to be explored. Here, we recast a previous theoretical study, and make explicit a potential contribution of velocity to cargo travel. We test this possibility experimentally, and demonstrate a strong negative correlation between single-motor velocity and cargo travel for transport driven by two motors. Our study thus discovers a previously unappreciated role of single-motor velocity in regulating multiple-motor transport. PMID:22672518

  11. Effect of Treating Streptozotocin-Induced Diabetic Rats With Sorbinil, Myo-Inositol or Aminoguanidine on Endoneurial Blood Flow, Motor Nerve Conduction Velocity and Vascular Function of Epineurial Arterioles of the Sciatic Nerve

    PubMed Central

    Coppey, Lawrence J.; Gellett, Jill S.; Davidson, Eric P.; Dunlap, Joyce A.

    2002-01-01

    Previously we have demonstrated that diabetes causes impairment in vascular function of epineurial vessels, which precedes the slowing of motor nerve conduction velocity. Treatment of diabetic rats with aldose reductase inhibitors, aminoguanidine or myo-inositol supplementation have been shown to improve motor nerve conduction velocity and/or decreased endoneurial blood flow. However, the effect these treatments have on vascular reactivity of epineurial vessels of the sciatic nerve is unknown. In these studies we examined the effect of treating streptozotocininduced rats with sorbinil, aminoguanidine or myo-inositol on motor nerve conduction velocity, endoneurial blood flow and endothelium dependent vascular relaxation of arterioles that provide circulation to the region of the sciatic nerve. Treating diabetic rats with sorbinil, aminoguanidine or myo-inositol improved the reduction of endoneurial blood flow and motor nerve conduction velocity. However, only sorbinil treatment significantly improved the diabetes-induced impairment of acetylcholinemediated vasodilation of epineurial vessels of the sciatic nerve. All three treatments were efficacious in preventing the appropriate metabolic derangements associated with either activation of the polyol pathway or increased nonenzymatic glycation. In addition, sorbinil was shown to prevent the diabetes-induced decrease in lens glutathione level. However, other markers of oxidative stress were not vividly improved by these treatments. These studies suggest that sorbinil treatment may be more effective in preventing neural dysfunction in diabetes than either aminoguanidine or myoinositol. PMID:11900277

  12. 21 CFR 882.1550 - Nerve conduction velocity measurement device.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nerve conduction velocity measurement device. 882... conduction velocity measurement device. (a) Identification. A nerve conduction velocity measurement device is a device which measures nerve conduction time by applying a stimulus, usually to a...

  13. 21 CFR 882.1550 - Nerve conduction velocity measurement device.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nerve conduction velocity measurement device. 882... conduction velocity measurement device. (a) Identification. A nerve conduction velocity measurement device is a device which measures nerve conduction time by applying a stimulus, usually to a...

  14. 21 CFR 882.1550 - Nerve conduction velocity measurement device.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nerve conduction velocity measurement device. 882... conduction velocity measurement device. (a) Identification. A nerve conduction velocity measurement device is a device which measures nerve conduction time by applying a stimulus, usually to a...

  15. 21 CFR 882.1550 - Nerve conduction velocity measurement device.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nerve conduction velocity measurement device. 882... conduction velocity measurement device. (a) Identification. A nerve conduction velocity measurement device is a device which measures nerve conduction time by applying a stimulus, usually to a...

  16. 21 CFR 882.1550 - Nerve conduction velocity measurement device.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nerve conduction velocity measurement device. 882... conduction velocity measurement device. (a) Identification. A nerve conduction velocity measurement device is a device which measures nerve conduction time by applying a stimulus, usually to a...

  17. Motor conduction measurement in myelopathy hand

    PubMed Central

    Shibuya, Ryoichi; Wada, Eiji; Iwasaki, Motoki; Yonenobu, Kazuo; Yoshikawa, Hideki

    2014-01-01

    Summary We studied the relationship between intramedullary high signal intensity (IMHSI) on T2-weighted magnetic resonance images and motor conduction in the spinal cords of cervical spondylotic myelopathy (CSM) patients. There was no significant difference between the biceps or triceps central motor conduction times (CMCTs) of the patients who did and did not exhibit IMHSI, whereas the abductor pollicis brevis CMCT was significantly longer in the patients who exhibited IMHSI (p<0.05) than in those who did not. The CMCT of the abductor pollicis brevis is sensitive to the degree of damage in the cervical spinal cord. Hand dysfunction is a characteristic of CSM regardless of the cervical level affected by the condition. The motor fibers innervating the intrinsic muscles of the hand in the long tract of the cervical spinal cord are more sensitive than other motor fibers. For this reason, we consider that myelopathy hand is a characteristic impairment of CSM. Transcranial magnetic stimulation of the hand motor cortex is useful for the evaluation of cervical myelopathy. PMID:25473737

  18. Simple Motor Control Concept Results High Efficiency at High Velocities

    NASA Astrophysics Data System (ADS)

    Starin, Scott; Engel, Chris

    2013-09-01

    The need for high velocity motors in space applications for reaction wheels and detectors has stressed the limits of Brushless Permanent Magnet Motors (BPMM). Due to inherent hysteresis core losses, conventional BPMMs try to balance the need for torque verses hysteresis losses. Cong-less motors have significantly less hysteresis losses but suffer from lower efficiencies. Additionally, the inherent low inductance in cog-less motors result in high ripple currents or high switching frequencies, which lowers overall efficiency and increases performance demands on the control electronics.However, using a somewhat forgotten but fully qualified technology of Isotropic Magnet Motors (IMM), extremely high velocities may be achieved at low power input using conventional drive electronics. This paper will discuss the trade study efforts and empirical test data on a 34,000 RPM IMM.

  19. Brushless DC Motors, Velocity and Position Control of the Brushless DC Motor.

    DTIC Science & Technology

    1986-06-01

    DC motor was designed using the Hall effect sensors. In addition, the position control of the brushless DC motor was developed using an optical encoder to sense angular position changes and a microprocessor to provide the desired position control. A Pittman 5111 wdg 1 brushless DC motor was used for this study. The design of the digital tachometer and pulse width modulator for velocity control and the design of the Z-80 based microprocessor controller and software design are described in

  20. Nerve conduction velocities and hair concentrations of trace elements in haemodialysis patients.

    PubMed

    Sasagawa, I; Nakada, T; Sawamura, T; Kato, T; Hashimoto, T; Ishigooka, M; Izumiya, K

    1993-01-01

    Nerve conduction velocities and hair concentrations of trace elements were studied in 19 male patients with chronic renal failure undergoing haemodialysis. Both motor and sensory nerve conduction velocities were significantly lower in haemodialysis patients as compared to controls (p < 0.001). Calcium and aluminium concentrations were significantly higher in patients (p < 0.01), however, vanadium and arsenic levels were significantly lower in patients (p < 0.01). In concentrations of copper and zinc there was no significant difference between patients and controls. There were no significant correlations between hair concentrations of trace elements and nerve conduction velocities except between calcium concentration and sensory nerve conduction velocity. These facts suggest that nerve conduction velocities are not influenced by changes of trace element concentrations in hair in patients with chronic renal failure undergoing haemodialysis.

  1. Adaptive H∞ nonlinear velocity tracking using RBFNN for linear DC brushless motor

    NASA Astrophysics Data System (ADS)

    Tsai, Ching-Chih; Chan, Cheng-Kain; Li, Yi Yu

    2012-01-01

    This article presents an adaptive H ∞ nonlinear velocity control for a linear DC brushless motor. A simplified model of this motor with friction is briefly recalled. The friction dynamics is described by the Lu Gre model and the online tuning radial basis function neural network (RBFNN) is used to parameterise the nonlinear friction function and un-modelled errors. An adaptive nonlinear H ∞ control method is then proposed to achieve velocity tracking, by assuming that the upper bounds of the ripple force, the changeable load and the nonlinear friction can be learned by the RBFNN. The closed-loop system is proven to be uniformly bounded using the Lyapunov stability theory. The feasibility and the efficacy of the proposed control are exemplified by conducting two velocity tracking experiments.

  2. [Central motor conduction evaluation in glycogenosis type III].

    PubMed

    Alaejos Fuentes, J A; López-Alburquerque, T; De Portugal Alvarez, J

    1997-05-01

    We report a 20-year-old man affected by glycogenosis type III with distal muscle weakness, more severe in distal leg muscles. The electromyogram showed myopathic features. Nerve conduction studies and central motor conduction after magnetic stimulation of the brain were normal. Our results suggest that there is no involvement of central motor pathways in this disease.

  3. Scaling law of velocity and conductivity in EK turbulence

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Yang, Fang; Wang, Guiren

    2014-11-01

    In microfluidics, when electrokinetic (EK) flow is applied with sufficiently high electric Rayleigh number (Rae) , turbulence can be achieved, and there can even be an universal equilibrium range of conductivity field. In this flow, a new scaling law region of velocity and conductivity structures where the energy cascade is dominated by electric body force (EBF) can be found. This is similar to the Bolgiano-Obukhov scaling law (BO59) in Rayleigh-Bénard (RB) convection. By both directly analyzing Navier-Stokes (N-S) equation and dimensional analysis, the scaling exponent of the second order moment of velocity structure function is 2/5, while that of conductivity structures is 4/5. Compared to the buoyancy in RB convection which decreases with decreasing length scale, EBF actually increases with decreasing spatial scales. This leads to two different microscales depending on the strength of EBF. The scaling law of velocity fluctuation is verified experimentally in a micro-EK turbulent flow. Although due to the restriction of geometry of our microchannel, the bandwidth of the EBF dominant subrange is narrow. By adjusting Rae and other parameters, a wider EBF dominant subrange is predicable. The work was supported by NSF under Grant No. CAREER CBET-0954977 and MRI CBET-1040227, respectively.

  4. Bifurcation of velocity distributions in cooperative transport of filaments by fast and slow motors.

    PubMed

    Li, Xin; Lipowsky, Reinhard; Kierfeld, Jan

    2013-02-05

    Several intracellular processes are governed by two different species of molecular motors, fast and slow ones, that both move in the same direction along the filaments but with different velocities. The transport of filaments arising from the cooperative action of these motors has been recently studied by three in vitro experiments, in which the filament velocity was measured for varying fraction of the fast motors adsorbed onto substrate surfaces in a gliding assay. As the fast motor fraction was increased, two experiments found a smooth change whereas the third one observed an abrupt increase of the filament velocity. Here, we show that all of these experimental results reflect the competition between fast and slow motors and can be understood in terms of an underlying saddle-node bifurcation. The comparison between theory and experiment leads to predictions for the detachment forces of the two motor species. Our theoretical study shows the existence of three different motility regimes: 1), fast transport with a single velocity; 2), slow transport with a single velocity; and 3), bistable transport, where the filament velocity stochastically switches between fast and slow transport. We determine the parameter regions for these regimes in terms of motility diagrams as a function of the surface fraction of fast motors and microscopic single-motor parameters. An abrupt increase of the filament velocity for an increasing fraction of fast motors is associated with the occurrence of bistable transport.

  5. Bifurcation of Velocity Distributions in Cooperative Transport of Filaments by Fast and Slow Motors

    PubMed Central

    Li, Xin; Lipowsky, Reinhard; Kierfeld, Jan

    2013-01-01

    Several intracellular processes are governed by two different species of molecular motors, fast and slow ones, that both move in the same direction along the filaments but with different velocities. The transport of filaments arising from the cooperative action of these motors has been recently studied by three in vitro experiments, in which the filament velocity was measured for varying fraction of the fast motors adsorbed onto substrate surfaces in a gliding assay. As the fast motor fraction was increased, two experiments found a smooth change whereas the third one observed an abrupt increase of the filament velocity. Here, we show that all of these experimental results reflect the competition between fast and slow motors and can be understood in terms of an underlying saddle-node bifurcation. The comparison between theory and experiment leads to predictions for the detachment forces of the two motor species. Our theoretical study shows the existence of three different motility regimes: 1), fast transport with a single velocity; 2), slow transport with a single velocity; and 3), bistable transport, where the filament velocity stochastically switches between fast and slow transport. We determine the parameter regions for these regimes in terms of motility diagrams as a function of the surface fraction of fast motors and microscopic single-motor parameters. An abrupt increase of the filament velocity for an increasing fraction of fast motors is associated with the occurrence of bistable transport. PMID:23442917

  6. Arc Conductance and Flow Velocity Affected by Transient Recovery Voltage

    NASA Astrophysics Data System (ADS)

    Fukuoka, Reo; Ishikawa, Yuya; Ono, Seisui; Sato, Ken; Yamamoto, Shinji; Iwao, Toru

    2016-09-01

    Recently, the stable supply of electric power is indispensable. The GCB (Gas Circuit Breaker) can prevent the spread of the fault current. However, it should have the reliability more. Therefore the GCB has been researched for performance improvement of the arc interruption of abnormal fault current without the fail. Therefore, it is important to prevent the breakdown such as the re-ignition and thermal re-ignition of arc after the arc interruption. It is necessary to reduce the arc conductance in order to prevent the re-ignition of arc. The arc conductance is derived from the temperature distribution and the volume of the arc. The temperature distribution of the arc is formed by convection. In this research, the arc conductance and flow velocity affected by transient recovery voltage are elucidated. The flow rate and temperature distribution of the arc is calculated with changing transient recovery voltage. In addition, the arc conductance is calculated in order to know the extinguish arc ability. As a result, when the transient recovery voltage increases, the probability of re-ignition increases. Therefore, the arc temperature and the arc conductance were increased.

  7. Robust transport by multiple motors with nonlinear force-velocity relations and stochastic load sharing

    NASA Astrophysics Data System (ADS)

    Kunwar, Ambarish; Mogilner, Alexander

    2010-03-01

    Transport by processive molecular motors plays an important role in many cell biological phenomena. In many cases, motors work together to transport cargos in the cell, so it is important to understand the mechanics of the multiple motors. Based on earlier modeling efforts, here we study effects of nonlinear force-velocity relations and stochastic load sharing on multiple motor transport. We find that when two or three motors transport the cargo, then the nonlinear and stochastic effects compensate so that the mechanical properties of the transport are robust. Similarly, the transport is insensitive to compliance of the cargo-motor links. Furthermore, the rate of movement against moderate loads is not improved by increasing the small number of motors. When the motor number is greater than 4, correlations between the motors become negligible, and the earlier analytical mean-field theory of the multiple motor transport holds. We predict that the effective diffusion of the cargo driven by the multiple motors under load increases by an order of magnitude compared to that for the single motor. Finally, our simulations predict that the stochastic effects are responsible for a significant dispersion of velocities generated by the 'tug-of-war' of the multiple opposing motors.

  8. Robust transport by multiple motors with nonlinear force-velocity relations and stochastic load sharing.

    PubMed

    Kunwar, Ambarish; Mogilner, Alexander

    2010-02-10

    Transport by processive molecular motors plays an important role in many cell biological phenomena. In many cases, motors work together to transport cargos in the cell, so it is important to understand the mechanics of the multiple motors. Based on earlier modeling efforts, here we study effects of nonlinear force-velocity relations and stochastic load sharing on multiple motor transport. We find that when two or three motors transport the cargo, then the nonlinear and stochastic effects compensate so that the mechanical properties of the transport are robust. Similarly, the transport is insensitive to compliance of the cargo-motor links. Furthermore, the rate of movement against moderate loads is not improved by increasing the small number of motors. When the motor number is greater than 4, correlations between the motors become negligible, and the earlier analytical mean-field theory of the multiple motor transport holds. We predict that the effective diffusion of the cargo driven by the multiple motors under load increases by an order of magnitude compared to that for the single motor. Finally, our simulations predict that the stochastic effects are responsible for a significant dispersion of velocities generated by the 'tug-of-war' of the multiple opposing motors.

  9. Robust transport by multiple motors with nonlinear force–velocity relations and stochastic load sharing

    PubMed Central

    Kunwar, Ambarish; Mogilner, Alexander

    2010-01-01

    Transport by processive molecular motors plays an important role in many cell biological phenomena. In many cases, motors work together to transport cargos in the cell, so it is important to understand the mechanics of the multiple motors. Based on earlier modeling efforts, here we study effects of nonlinear force–velocity relations and stochastic load sharing on multiple motor transport. We find that when two or three motors transport the cargo, then the nonlinear and stochastic effects compensate so that the mechanical properties of the transport are robust. Similarly, the transport is insensitive to compliance of the cargo-motor links. Furthermore, the rate of movement against moderate loads is not improved by increasing the small number of motors. When the motor number is greater than 4, correlations between the motors become negligible, and the earlier analytical mean-field theory of the multiple motor transport holds. We predict that the effective diffusion of the cargo driven by the multiple motors under load increases by an order of magnitude compared to that for the single motor. Finally, our simulations predict that the stochastic effects are responsible for a significant dispersion of velocities generated by the ‘tug-of-war’ of the multiple opposing motors. PMID:20147778

  10. [Multifocal-motor neuropathy and motor neuropathy with multifocal conduction block (Lewis-Sumner syndrome)].

    PubMed

    Finsterer, J; Mamoli, B

    1995-01-01

    Multifocal motor neuropathy, which mimics lower motor neuron disease, is a rare and curious demyelinating neuropathy characterised by slowly progressive, asymmetric limb weakness within the distribution of individual peripheral nerves, wasting, cramps, fasciculations and rare sensory involvement, but without upper motor neuron signs. The cardinal feature and primary pathophysiological basis for the weakness is the multifocal motor conduction block which remains stable for years at the same site and is confined to motor axons. It is defined as > 50% reduction in both the CMAP and the negative peak area on proximal stimulation, as compared with the distal stimulus response without any change in the negative peak duration. Nerves at the site of the conduction block show demyelination, endoneural edema, rudimentary onion bulbs and lymphocytic inflammation. Sensory nerves may show mild demyelination, axon loss and lymphocytic inflammation. The majority of patients shows elevated titers of anti-glycolipid antibodies, which may block the Na+ channels, produce demyelination or interfere with remyelination. However, their role in the pathogenesis of multifocal motor neuropathy remains uncertain. Multifocal motor neuropathy is regarded as the predominantly motor variant of chronic inflammatory demyelinating polyneuropathy and can be treated best with immunoglobulins and cyclophosphamide.

  11. Velocity Fluctuations in Kinesin-1 Gliding Motility Assays Originate in Motor Attachment Geometry Variations.

    PubMed

    Palacci, Henri; Idan, Ofer; Armstrong, Megan J; Agarwal, Ashutosh; Nitta, Takahiro; Hess, Henry

    2016-08-09

    Motor proteins such as myosin and kinesin play a major role in cellular cargo transport, muscle contraction, cell division, and engineered nanodevices. Quantifying the collective behavior of coupled motors is critical to our understanding of these systems. An excellent model system is the gliding motility assay, where hundreds of surface-adhered motors propel one cytoskeletal filament such as an actin filament or a microtubule. The filament motion can be observed using fluorescence microscopy, revealing fluctuations in gliding velocity. These velocity fluctuations have been previously quantified by a motional diffusion coefficient, which Sekimoto and Tawada explained as arising from the addition and removal of motors from the linear array of motors propelling the filament as it advances, assuming that different motors are not equally efficient in their force generation. A computational model of kinesin head diffusion and binding to the microtubule allowed us to quantify the heterogeneity of motor efficiency arising from the combination of anharmonic tail stiffness and varying attachment geometries assuming random motor locations on the surface and an absence of coordination between motors. Knowledge of the heterogeneity allows the calculation of the proportionality constant between the motional diffusion coefficient and the motor density. The calculated value (0.3) is within a standard error of our measurements of the motional diffusion coefficient on surfaces with varying motor densities calibrated by landing rate experiments. This allowed us to quantify the loss in efficiency of coupled molecular motors arising from heterogeneity in the attachment geometry.

  12. System and method for determining velocity of electrically conductive fluid

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A. (Inventor); Korman, Valentin (Inventor); Markusic, Thomas E. (Inventor); Stanojev, Boris Johann (Inventor)

    2008-01-01

    A flowing electrically-conductive fluid is controlled between an upstream and downstream location thereof to insure that a convection timescale of the flowing fluid is less than a thermal diffusion timescale of the flowing fluid. First and second nodes of a current-carrying circuit are coupled to the fluid at the upstream location. A current pulse is applied to the current-carrying circuit so that the current pulse travels through the flowing fluid to thereby generate a thermal feature therein at the upstream location. The thermal feature is convected to the downstream location where it is monitored to detect a peak associated with the thermal feature so-convected. The velocity of the fluid flow is determined using a time-of-flight analysis.

  13. Motor coupling through lipid membranes enhances transport velocities for ensembles of myosin Va

    PubMed Central

    Nelson, Shane R.; Trybus, Kathleen M.; Warshaw, David M.

    2014-01-01

    Myosin Va is an actin-based molecular motor responsible for transport and positioning of a wide array of intracellular cargoes. Although myosin Va motors have been well characterized at the single-molecule level, physiological transport is carried out by ensembles of motors. Studies that explore the behavior of ensembles of molecular motors have used nonphysiological cargoes such as DNA linkers or glass beads, which do not reproduce one key aspect of vesicular systems—the fluid intermotor coupling of biological lipid membranes. Using a system of defined synthetic lipid vesicles (100- to 650-nm diameter) composed of either 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) (fluid at room temperature) or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) (gel at room temperature) with a range of surface densities of myosin Va motors (32–125 motors per μm2), we demonstrate that the velocity of vesicle transport by ensembles of myosin Va is sensitive to properties of the cargo. Gel-state DPPC vesicles bound with multiple motors travel at velocities equal to or less than vesicles with a single myosin Va (∼450 nm/s), whereas surprisingly, ensembles of myosin Va are able to transport fluid-state DOPC vesicles at velocities significantly faster (>700 nm/s) than a single motor. To explain these data, we developed a Monte Carlo simulation that suggests that these reductions in velocity can be attributed to two distinct mechanisms of intermotor interference (i.e., load-dependent modulation of stepping kinetics and binding-site exclusion), whereas faster transport velocities are consistent with a model wherein the normal stepping behavior of the myosin is supplemented by the preferential detachment of the trailing motor from the actin track. PMID:25201964

  14. A velocity command stepper motor for CSI application

    NASA Technical Reports Server (NTRS)

    Sulla, Jeffrey L.; Juang, Jer-Nan; Horta, Lucas G.

    1991-01-01

    The application of linear force actuators for vibration suppression of flexible structures has received much attention in recent years. A linear force actuator consists of a movable mass that is restrained such that its motion is linear. By application of a force to the mass, an equal and opposite reaction force can be applied to a structure. The use of an industrial linear stepper motor as a reaction mass actuator is described. With the linear stepper motor mounted on a simple test beam and the NASA Mini-Mast, output feedback of acceleration or displacement are used to augment the structural damping of the test articles. Significant increases in damping were obtained for both the test beam and the Mini-Mast.

  15. Acute Motor Axonal Neuropathy (Aman) With Motor Conduction Blocks In Childhood; Case Report

    PubMed Central

    Yildirim, Serhan; Adviye, Rahşan; Gül, Hakan Levent; Türk Börü, Ülkü

    2016-01-01

    Objective Acute motor axonal neuropathy (AMAN), characterized with decreased compound muscle action potentials (CMAP) and absence of demyelinating findings in electrophysiological studies, is a subtype of Guillain-Barre Syndrome (GBS). A 4 yr-old male patient presented with ascending weakness, dysarthria and dysphagia to İstanbul Dr. Lütfi Kırdar Kartal Training and Research Hospital Neurology outpatient for three days to in 2012. Dysphonia, restricted eye movements, flaccid tetraplegia and areflexia were found in neurological examination. There were motor conduction blocks in all peripheral nerves in electrophysiological studies.According to these findings the patient was diagnosed as Acute Inflammatory Demyelinating Polyradiculoneuropathy (AIDP). Reduction of CMAP amplitudes in posterior tibial nerve, absence of CMAPs in median, ulnar and peroneal nerves and loss of motor conduction blocks were found in following electrophysiological studies. According to these findings, patient was diagnosed as AMAN. Motor conduction blocks may appear in early stage of AMAN and they disappear in later examinations. That’s why electrophysiological studies must be repeated in patients with GBS. PMID:27057191

  16. Perception of the color red enhances the force and velocity of motor output.

    PubMed

    Elliot, Andrew J; Aarts, Henk

    2011-04-01

    The present research examined whether perception of the color red influences basic motor functioning. Prior research on color and motor functioning has been guided by ill-defined theoretical statements, and has been plagued by methodological problems. Drawing on theoretical and empirical work on the threat-behavior link in human and nonhuman animals, we proposed and tested the prediction that perceiving red enhances the force and velocity of motor output. Experiment 1 demonstrated that red, relative to gray (matched to red on lightness), facilitates pinchgrip force. Experiment 2 demonstrated that red, relative to gray (matched to red on lightness) and blue (matched to red on lightness and chroma) facilitates handgrip force and the velocity of that force. These findings clearly establish a link between red and basic motor action, illustrate the importance of rigorous experimental methods when testing color effects, and highlight the need to attend to the functional, as well as aesthetic, value of color.

  17. Muscle fibre conduction velocity during a 30-s Wingate anaerobic test.

    PubMed

    Stewart, David; Farina, Dario; Shen, Chao; Macaluso, Andrea

    2011-06-01

    Ten male volunteers (age 29.2 ± 5.2 years, mean ± SD) were recruited to test the hypothesis that muscle fibre conduction velocity (MFCV) would decrease with power output during a 30-s Wingate test on a mechanically-braked cycle ergometer. Prior to the main test, the optimal pre-fixed load corresponding to the highest power output was selected following a random series of six 10-s sprints. Surface electromyographic (EMG) signals were detected from the right vastus lateralis with linear adhesive arrays of eight electrodes. Power output decreased significantly from 6-s until the end of the test (860.9 ± 207.8 vs. 360.9 ± 11.4 W, respectively) and was correlated with MFCV (R=0.543, P<0.01), which also declined significantly by 26.8 ± 11% (P<0.05). There was a tendency for the mean frequency of the EMG power spectrum (MNF) to decrease, but average rectified values (ARV) remained unchanged throughout the test. The parallel decline of MFCV with power output suggests changes in fibre membrane properties. The unaltered ARV, together with the declined MFCV, would indicate either a decrease in discharge rate, de-recruitment of fatigued motor units or elongation of still present motor unit action potentials.

  18. Motor conduction block and high titres of anti-GM1 ganglioside antibodies: pathological evidence of a motor neuropathy in a patient with lower motor neuron syndrome.

    PubMed Central

    Adams, D; Kuntzer, T; Steck, A J; Lobrinus, A; Janzer, R C; Regli, F

    1993-01-01

    A patient with a progressive lower motor neuron syndrome and neurophysiological evidence of motor axon loss, multifocal proximal motor nerve conduction block, and high titres of anti-ganglioside GM1 antibodies. Neuropathological findings included a predominantly proximal motor radiculoneuropathy with multifocal IgG and IgM deposits on nerve fibres associated with a loss of spinal motor neurons. These findings support an autoimmune origin of this lower motor neuron syndrome with retrograde degeneration of spinal motor neurons and severe neurogenic muscular atrophy. Images PMID:8410039

  19. An ultrasonic motor driven by the phase-velocity difference between two traveling waves.

    PubMed

    Bai, Dongzhe; Ishii, Takaaki; Nakamura, Kentaro; Ueha, Sadayuki; Yonezawa, Toshiaki; Takahashi, Tomokazu

    2004-06-01

    This paper presents a new ultrasonic motor in which the rotor rotation speed is locked by the phase-velocity difference between the two traveling waves propagating on the stator and the rotor. First, the unique construction to excite two traveling waves both in the stator and the rotor is described. Then, the operation principle of the present motor is revealed by our careful experiments. Dynamics of the two traveling waves are measured by an in-plane laser Doppler vibrometer under various conditions, as well as the motor performances. Our experiments show that the rotation speed of the motor is equal to the phase-velocity difference between the two traveling waves on the contact surfaces of rotor and stator. It is confirmed that the rotor rotates so as to cancel the phase-velocity difference between the traveling vibrations along the circumferences of the rotor and stator. If the load does not exceed the maximum torque that is determined by the vibration amplitude, the rotation speed is subject only to the phase-velocity difference.

  20. On the relationship between joint angular velocity and motor cortical discharge during reaching.

    PubMed

    Reina, G A; Moran, D W; Schwartz, A B

    2001-06-01

    Single-unit activity in area M1 was recorded in awake, behaving monkeys during a three-dimensional (3D) reaching task performed in a virtual reality environment. This study compares motor cortical discharge rate to both the hand's velocity and the arm's joint angular velocities. Hand velocity is considered a parameter of extrinsic space because it is measured in the Cartesian coordinate system of the monkey's workspace. Joint angular velocity is considered a parameter of intrinsic space because it is measured relative to adjacent arm/body segments. In the initial analysis, velocity was measured as the difference in hand position or joint posture between the beginning and ending of the reach. Cortical discharge rate was taken as the mean activity between these two times. This discharge rate was compared through a regression analysis to either an extrinsic-coordinate model based on the three components of hand velocity or to an intrinsic-coordinate model based on seven joint angular velocities. The model showed that velocities about four degrees-of-freedom (elbow flexion/extension, shoulder flexion/extension, shoulder internal/external rotation, and shoulder adduction/abduction) were those best represented in the sampled population of recorded activity. Patterns of activity recorded across the cortical population at each point in time throughout the task were used in a second analysis to predict the temporal profiles of joint angular velocity and hand velocity. The population of cortical units from area M1 matched the hand velocity and three of the four major joint angular velocities. However, shoulder adduction/abduction could not be predicted even though individual cells showed good correlation to movement on this axis. This was also the only major degree-of-freedom not well correlated to hand velocity, suggesting that the other apparent relations between joint angular velocity and neuronal activity may be due to intrinsic-extrinsic correlations inherent in

  1. A Study on High Thermal Conductive Insulation for Claw Teeth Motors

    NASA Astrophysics Data System (ADS)

    Yoshitake, Yuichiro; Obata, Koji; Enomoto, Yuji; Okabe, Yoshiaki

    To increase the power density of motors in a wide range of fields from home appliance to power industry, we proposed two new high thermal conductive insulation systems for the motors. They were a glass cross insulation system and a resin coated insulation system without forced cooling devices such as a cooling fan. Their thermal and insulation characteristics were measured and analyzed, and optimum thermal conductive structures for claw teeth motors were discussed through robust design and thermal network analysis. Experiment on prototype motors with the highest thermal conductive epoxy resin (5 W/mK) and the proposed systems, revealed that the temperature rise of motor coils was decreased; their temperature reached 73 % of that of the motor coils with standard insulation and normal resin (0.6 W/mK). Furthermore, partial discharge inception voltage (PDIV) and breakdown voltage (BDV) were measured, and we verified that resin coated insulation motors could withstand as high a voltage as normal insulation motors.

  2. Analysis and application of a velocity command motor as a reaction mass actuator

    NASA Technical Reports Server (NTRS)

    Sulla, Jeffrey L.; Juang, Jer-Nan; Horta, Lucas G.

    1990-01-01

    A commercially available linear stepper motor is applied as a reaction mass (RM) actuator. With the actuator operating in the (RM) relative-velocity command mode, open-loop and closed-loop testing is performed to determine operational limits. With the actuator mounted on a simple beam structure, root strain, RM acceleration, or beam acceleration is used in the feedback loop to augment the structural damping. The RM relative position is also used as feedback to ensure that the RM remains centered.

  3. Neural control of computer cursor velocity by decoding motor cortical spiking activity in humans with tetraplegia

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Phil; Simeral, John D.; Hochberg, Leigh R.; Donoghue, John P.; Black, Michael J.

    2008-12-01

    Computer-mediated connections between human motor cortical neurons and assistive devices promise to improve or restore lost function in people with paralysis. Recently, a pilot clinical study of an intracortical neural interface system demonstrated that a tetraplegic human was able to obtain continuous two-dimensional control of a computer cursor using neural activity recorded from his motor cortex. This control, however, was not sufficiently accurate for reliable use in many common computer control tasks. Here, we studied several central design choices for such a system including the kinematic representation for cursor movement, the decoding method that translates neuronal ensemble spiking activity into a control signal and the cursor control task used during training for optimizing the parameters of the decoding method. In two tetraplegic participants, we found that controlling a cursor's velocity resulted in more accurate closed-loop control than controlling its position directly and that cursor velocity control was achieved more rapidly than position control. Control quality was further improved over conventional linear filters by using a probabilistic method, the Kalman filter, to decode human motor cortical activity. Performance assessment based on standard metrics used for the evaluation of a wide range of pointing devices demonstrated significantly improved cursor control with velocity rather than position decoding. Disclosure. JPD is the Chief Scientific Officer and a director of Cyberkinetics Neurotechnology Systems (CYKN); he holds stock and receives compensation. JDS has been a consultant for CYKN. LRH receives clinical trial support from CYKN.

  4. History dependence of human muscle-fiber conduction velocity during voluntary isometric contractions

    PubMed Central

    Lateva, Zoia C.

    2011-01-01

    The conduction velocity (CV) of a muscle fiber is affected by the fiber's discharge history going back ∼1 s. We investigated this dependence by measuring CV fluctuations during voluntary isometric contractions of the human brachioradialis muscle. We recorded electromyogram (EMG) signals simultaneously from multiple intramuscular electrodes, identified potentials belonging to the same motor unit using EMG decomposition, and estimated the CV of each discharge from the interpotential interval. In 12 of 14 subjects, CV increased by ∼10% during the first second after recruitment and then fluctuated by about ±2% in a way that mirrored the fluctuations in the instantaneous firing rate. The CV profile could be precisely described in terms of the discharge history by a simple mathematical model. In the other two subjects, and one subject retested after cooling the arm, the CV fluctuations were inversely correlated with instantaneous firing rate. In all subjects, CV was additionally affected by very short interdischarge intervals (<25 ms): it was increased in doublets at recruitment, but decreased in doublets during continuous firing and after short interdischarge intervals in doubly innervated fibers. CV also exhibited a slow trend of about −0.05%/s that did not depend on the immediate discharge history. We suggest that measurements of CV fluctuations during voluntary contractions, or during stimulation protocols that involve longer and more complex stimulation patterns than are currently being used, may provide a sensitive approach for estimating the dynamic characteristics of ion channels in the human muscle-fiber membrane. PMID:21565985

  5. Effect of extracellular potassium accumulation on muscle fiber conduction velocity: a simulation study.

    PubMed

    Fortune, Emma; Lowery, Madeleine M

    2009-10-01

    A progressive reduction in muscle fiber conduction velocity is typically observed during fatiguing muscle contraction. Although the exact causes of the conduction velocity decrease have not yet been fully established, increasing evidence suggests that changes in extracellular potassium concentration may be largely responsible. In this study, a mathematical model was developed to examine the effect of extracellular potassium concentration on the muscle fiber action potential and conduction velocity. The model was used to simulate changes in extracellular potassium concentration at a range of temperatures and extracellular potassium accumulation during repetitive stimulation of the muscle fiber at 37 degrees C. The action potential broadened, and its amplitude and conduction velocity decreased as extracellular potassium concentration increased. The potassium-induced changes in action potential shape and conduction velocity were eliminated when the inward rectifier channels were removed from the model. The results support the hypothesis that accumulation of extracellular potassium ions may be a major contributor to the reduction in muscle fiber conduction velocity and loss of membrane excitability during fatiguing contractions. They additionally suggest that inward rectifier currents play a critical role in potassium-induced membrane depolarization, leading to increased sodium inactivation and resulting in the observed reduction in conduction velocity and membrane excitability.

  6. Discrete Step Sizes of Molecular Motors Lead to Bimodal Non-Gaussian Velocity Distributions under Force.

    PubMed

    Vu, Huong T; Chakrabarti, Shaon; Hinczewski, Michael; Thirumalai, D

    2016-08-12

    Fluctuations in the physical properties of biological machines are inextricably linked to their functions. Distributions of run lengths and velocities of processive molecular motors, like kinesin-1, are accessible through single-molecule techniques, but rigorous theoretical models for these probabilities are lacking. Here, we derive exact analytic results for a kinetic model to predict the resistive force (F)-dependent velocity [P(v)] and run length [P(n)] distribution functions of generic finitely processive molecular motors. Our theory quantitatively explains the zero force kinesin-1 data for both P(n) and P(v) using the detachment rate as the only parameter. In addition, we predict the F dependence of these quantities. At nonzero F, P(v) is non-Gaussian and is bimodal with peaks at positive and negative values of v, which is due to the discrete step size of kinesin-1. Although the predictions are based on analyses of kinesin-1 data, our results are general and should hold for any processive motor, which walks on a track by taking discrete steps.

  7. Discrete Step Sizes of Molecular Motors Lead to Bimodal Non-Gaussian Velocity Distributions under Force

    NASA Astrophysics Data System (ADS)

    Vu, Huong T.; Chakrabarti, Shaon; Hinczewski, Michael; Thirumalai, D.

    2016-08-01

    Fluctuations in the physical properties of biological machines are inextricably linked to their functions. Distributions of run lengths and velocities of processive molecular motors, like kinesin-1, are accessible through single-molecule techniques, but rigorous theoretical models for these probabilities are lacking. Here, we derive exact analytic results for a kinetic model to predict the resistive force (F )-dependent velocity [P (v )] and run length [P (n )] distribution functions of generic finitely processive molecular motors. Our theory quantitatively explains the zero force kinesin-1 data for both P (n ) and P (v ) using the detachment rate as the only parameter. In addition, we predict the F dependence of these quantities. At nonzero F , P (v ) is non-Gaussian and is bimodal with peaks at positive and negative values of v , which is due to the discrete step size of kinesin-1. Although the predictions are based on analyses of kinesin-1 data, our results are general and should hold for any processive motor, which walks on a track by taking discrete steps.

  8. Motor patterns of the small intestine explained by phase-amplitude coupling of two pacemaker activities: the critical importance of propagation velocity.

    PubMed

    Huizinga, Jan D; Parsons, Sean P; Chen, Ji-Hong; Pawelka, Andrew; Pistilli, Marc; Li, Chunpei; Yu, Yuanjie; Ye, Pengfei; Liu, Qing; Tong, Mengting; Zhu, Yong Fang; Wei, Defei

    2015-09-15

    Phase-amplitude coupling of two pacemaker activities of the small intestine, the omnipresent slow wave activity generated by interstitial cells of Cajal of the myenteric plexus (ICC-MP) and the stimulus-dependent rhythmic transient depolarizations generated by ICC of the deep muscular plexus (ICC-DMP), was recently hypothesized to underlie the orchestration of the segmentation motor pattern. The aim of the present study was to increase our understanding of phase-amplitude coupling through modeling. In particular the importance of propagation velocity of the ICC-DMP component was investigated. The outcome of the modeling was compared with motor patterns recorded from the rat or mouse intestine from which propagation velocities within the different patterns were measured. The results show that the classical segmentation motor pattern occurs when the ICC-DMP component has a low propagation velocity (<0.05 cm/s). When the ICC-DMP component has a propagation velocity in the same order of magnitude as that of the slow wave activity (∼1 cm/s), cluster type propulsive activity occurs which is in fact the dominant propulsive activity of the intestine. Hence, the only difference between the generation of propagating cluster contractions and the Cannon-type segmentation motor pattern is the propagation velocity of the low-frequency component, the rhythmic transient depolarizations originating from the ICC-DMP. Importantly, the proposed mechanism explains why both motor patterns have distinct rhythmic waxing and waning of the amplitude of contractions. The hypothesis is brought forward that the velocity is modulated by neural regulation of gap junction conductance within the ICC-DMP network.

  9. Motor patterns of the small intestine explained by phase-amplitude coupling of two pacemaker activities: the critical importance of propagation velocity

    PubMed Central

    Parsons, Sean P.; Chen, Ji-Hong; Pawelka, Andrew; Pistilli, Marc; Li, Chunpei; Yu, Yuanjie; Ye, Pengfei; Liu, Qing; Tong, Mengting; Zhu, Yong Fang; Wei, Defei

    2015-01-01

    Phase-amplitude coupling of two pacemaker activities of the small intestine, the omnipresent slow wave activity generated by interstitial cells of Cajal of the myenteric plexus (ICC-MP) and the stimulus-dependent rhythmic transient depolarizations generated by ICC of the deep muscular plexus (ICC-DMP), was recently hypothesized to underlie the orchestration of the segmentation motor pattern. The aim of the present study was to increase our understanding of phase-amplitude coupling through modeling. In particular the importance of propagation velocity of the ICC-DMP component was investigated. The outcome of the modeling was compared with motor patterns recorded from the rat or mouse intestine from which propagation velocities within the different patterns were measured. The results show that the classical segmentation motor pattern occurs when the ICC-DMP component has a low propagation velocity (<0.05 cm/s). When the ICC-DMP component has a propagation velocity in the same order of magnitude as that of the slow wave activity (∼1 cm/s), cluster type propulsive activity occurs which is in fact the dominant propulsive activity of the intestine. Hence, the only difference between the generation of propagating cluster contractions and the Cannon-type segmentation motor pattern is the propagation velocity of the low-frequency component, the rhythmic transient depolarizations originating from the ICC-DMP. Importantly, the proposed mechanism explains why both motor patterns have distinct rhythmic waxing and waning of the amplitude of contractions. The hypothesis is brought forward that the velocity is modulated by neural regulation of gap junction conductance within the ICC-DMP network. PMID:26135802

  10. AC motor controller with 180 degree conductive switches

    NASA Technical Reports Server (NTRS)

    Oximberg, Carol A. (Inventor)

    1995-01-01

    An ac motor controller is operated by a modified time-switching scheme where the switches of the inverter are on for electrical-phase-and-rotation intervals of 180.degree. as opposed to the conventional 120.degree.. The motor is provided with three-phase drive windings, a power inverter for power supplied from a dc power source consisting of six switches, and a motor controller which controls the current controlled switches in voltage-fed mode. During full power, each switch is gated continuously for three successive intervals of 60.degree. and modulated for only one of said intervals. Thus, during each 60.degree. interval, the two switches with like signs are on continuously and the switch with the opposite sign is modulated.

  11. Effects of Bed Rest on Conduction Velocity of the Triceps Surae Stretch Reflex and Postural Control

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.; Wood, S. J.; Cerisano, J. M.; Kofman, I. S.; Fisher, E. A.; Esteves, J. T.; Taylor, L. C.; DeDios, Y. E.; Harm, D. L.

    2011-01-01

    Despite rigorous exercise and nutritional management during space missions, astronauts returning from microgravity exhibit neuromuscular deficits and a significant loss in muscle mass in the postural muscles of the lower leg. Similar changes in the postural muscles occur in subjects participating in long-duration bed rest studies. These adaptive muscle changes manifest as a reduction in reflex conduction velocity during head-down bed rest. Because the stretch reflex encompasses both the peripheral (muscle spindle and nerve axon) and central (spinal synapse) components involved in adaptation to calf muscle unloading, it may be used to provide feedback on the general condition of neuromuscular function, and might be used to evaluate the effectiveness of countermeasures aimed at preserving muscle mass and function during periods of unloading. Stretch reflexes were measured on 18 control subjects who spent 60 to 90 days in continuous 6 deg head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 degrees at a peak velocity of about 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender. Computerized posturography was also conducted on these same subjects before and after bed rest as part of the standard measures. Peak-to-peak sway was measured during Sensory Organization Tests (SOTs) to evaluate changes in the ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Although no gender differences were found, a significant increase in reflex latency and a significant decrease in CV were observed during the bed

  12. Discrete Kinetic Models for Molecular Motors: Asymptotic Velocity and Gaussian Fluctuations

    NASA Astrophysics Data System (ADS)

    Faggionato, Alessandra; Silvestri, Vittoria

    2014-12-01

    We consider random walks on quasi one dimensional lattices, as introduced in Faggionato and Silvestri (Random Walks on Quasi One Dimensional Lattices: Large Deviations and Fluctuation Theorems, 2014). This mathematical setting covers a large class of discrete kinetic models for non-cooperative molecular motors on periodic tracks. We derive general formulas for the asymptotic velocity and diffusion coefficient, and we show how to reduce their computation to suitable linear systems of the same degree of a single fundamental cell, with possible linear chain removals. We apply the above results to special families of kinetic models, also catching some errors in the biophysics literature.

  13. Portable Conduction Velocity Experiments Using Earthworms for the College and High School Neuroscience Teaching Laboratory

    ERIC Educational Resources Information Center

    Shannon, Kyle M.; Gage, Gregory J.; Jankovic, Aleksandra; Wilson, W. Jeffrey; Marzullo, Timothy C.

    2014-01-01

    The earthworm is ideal for studying action potential conduction velocity in a classroom setting, as its simple linear anatomy allows easy axon length measurements and the worm's sparse coding allows single action potentials to be easily identified. The earthworm has two giant fiber systems (lateral and medial) with different conduction velocities…

  14. Field-tracing approach to determine flow velocity and hydraulic conductivity in saturated peat soils

    SciTech Connect

    Gafni, A.

    1986-01-01

    A tracing methodology based on the point dilution concept was developed to quantify groundwater velocities in saturated peat soils. Groundwater velocity was measured in four different peatlands. The steepest hydraulic gradient and the dominant direction of groundwater flow were determined for each peatland. The hydraulic conductivity (K) of selected peat layers was estimated from measured groundwater velocity and hydraulic gradient using Darcy's equation. The effective porosity of three peat layers was determined using the pressure plate technique. The estimated hydraulic parameters of one of the bags were further evaluated by analyzing a rainfall-runoff event that exhibited groundwater discharge.

  15. A variant of multifocal motor neuropathy with acute, generalised presentation and persistent conduction blocks

    PubMed Central

    Lefaucheur, J; Gregson, N; Gray, I; von Raison, F; Bertocchi, M; Creange, A

    2003-01-01

    Objective:Multifocal motor neuropathy with persistent conduction blocks is classically described as a chronic neuropathy with progressive onset, and acute forms have not previously been characterised. We report four cases of severe motor impairment with acute and generalised onset and with persistent motor conduction blocks. Patients and results:An acute tetraparesis with diffuse areflexia but little or no sensory disturbance was the clinical picture. Serial electrophysiological tests showed persistent multifocal motor conduction blocks with absent F waves in most tested motor nerves. No or minor abnormalities of the sensory nerve action potentials were observed. Cerebrospinal fluid contained normal or mildly increased protein levels (<1 g/l) without cells. Campylobacter jejuni serology was negative in three patients and consistent with past infection in one patient. Anti-ganglioside antibodies were positive in three patients. A five day course of intravenous immunoglobulins produced nearly complete symptom resolution in three patients and was ineffective in one patient. Conclusion:Because of the persistence of multifocal motor conduction blocks for several weeks or months as the isolated electrophysiological feature, these cases could not be consistent with Guillain–Barré syndrome or chronic inflammatory demyelinating polyneuropathy. They suggest an original variant of multifocal motor neuropathy with an acute and generalised initial presentation and persistent motor conduction blocks affecting all four limbs. PMID:14617715

  16. Portable conduction velocity experiments using earthworms for the college and high school neuroscience teaching laboratory.

    PubMed

    Shannon, Kyle M; Gage, Gregory J; Jankovic, Aleksandra; Wilson, W Jeffrey; Marzullo, Timothy C

    2014-03-01

    The earthworm is ideal for studying action potential conduction velocity in a classroom setting, as its simple linear anatomy allows easy axon length measurements and the worm's sparse coding allows single action potentials to be easily identified. The earthworm has two giant fiber systems (lateral and medial) with different conduction velocities that can be easily measured by manipulating electrode placement and the tactile stimulus. Here, we present a portable and robust experimental setup that allows students to perform conduction velocity measurements within a 30-min to 1-h laboratory session. Our improvement over this well-known preparation is the combination of behaviorally relevant tactile stimuli (avoiding electrical stimulation) with the invention of minimal, low-cost, and portable equipment. We tested these experiments during workshops in both a high school and college classroom environment and found positive learning outcomes when we compared pre- and posttests taken by the students.

  17. Dynamic Modulation of Myelination in Response to Visual Stimuli Alters Optic Nerve Conduction Velocity

    PubMed Central

    Etxeberria, Ainhoa; Hokanson, Kenton C.; Dao, Dang Q.; Mayoral, Sonia R.; Mei, Feng; Redmond, Stephanie A.; Ullian, Erik M.

    2016-01-01

    Myelin controls the time required for an action potential to travel from the neuronal soma to the axon terminal, defining the temporal manner in which information is processed within the CNS. The presence of myelin, the internodal length, and the thickness of the myelin sheath are powerful structural factors that control the velocity and fidelity of action potential transmission. Emerging evidence indicates that myelination is sensitive to environmental experience and neuronal activity. Activity-dependent modulation of myelination can dynamically alter action potential conduction properties but direct functional in vivo evidence and characterization of the underlying myelin changes is lacking. We demonstrate that in mice long-term monocular deprivation increases oligodendrogenesis in the retinogeniculate pathway but shortens myelin internode lengths without affecting other structural properties of myelinated fibers. We also demonstrate that genetically attenuating synaptic glutamate neurotransmission from retinal ganglion cells phenocopies the changes observed after monocular deprivation, suggesting that glutamate may constitute a signal for myelin length regulation. Importantly, we demonstrate that visual deprivation and shortened internodes are associated with a significant reduction in nerve conduction velocity in the optic nerve. Our results reveal the importance of sensory input in the building of myelinated fibers and suggest that this activity-dependent alteration of myelination is important for modifying the conductive properties of brain circuits in response to environmental experience. SIGNIFICANCE STATEMENT Oligodendrocyte precursor cells differentiate into mature oligodendrocytes and are capable of ensheathing axons with myelin without molecular cues from neurons. However, this default myelination process can be modulated by changes in neuronal activity. Here, we show, for the first time, that experience-dependent activity modifies the length of myelin

  18. Mapping conduction velocity of early embryonic hearts with a robust fitting algorithm

    PubMed Central

    Gu, Shi; Wang, Yves T; Ma, Pei; Werdich, Andreas A; Rollins, Andrew M; Jenkins, Michael W

    2015-01-01

    Cardiac conduction maturation is an important and integral component of heart development. Optical mapping with voltage-sensitive dyes allows sensitive measurements of electrophysiological signals over the entire heart. However, accurate measurements of conduction velocity during early cardiac development is typically hindered by low signal-to-noise ratio (SNR) measurements of action potentials. Here, we present a novel image processing approach based on least squares optimizations, which enables high-resolution, low-noise conduction velocity mapping of smaller tubular hearts. First, the action potential trace measured at each pixel is fit to a curve consisting of two cumulative normal distribution functions. Then, the activation time at each pixel is determined based on the fit, and the spatial gradient of activation time is determined with a two-dimensional (2D) linear fit over a square-shaped window. The size of the window is adaptively enlarged until the gradients can be determined within a preset precision. Finally, the conduction velocity is calculated based on the activation time gradient, and further corrected for three-dimensional (3D) geometry that can be obtained by optical coherence tomography (OCT). We validated the approach using published activation potential traces based on computer simulations. We further validated the method by adding artificially generated noise to the signal to simulate various SNR conditions using a curved simulated image (digital phantom) that resembles a tubular heart. This method proved to be robust, even at very low SNR conditions (SNR = 2-5). We also established an empirical equation to estimate the maximum conduction velocity that can be accurately measured under different conditions (e.g. sampling rate, SNR, and pixel size). Finally, we demonstrated high-resolution conduction velocity maps of the quail embryonic heart at a looping stage of development. PMID:26114034

  19. Velocity, temperature, and electrical conductivity profiles in hydrogen-oxygen MHD duct flows

    NASA Technical Reports Server (NTRS)

    Greywall, M. S.; Pian, C. C. P.

    1978-01-01

    Two-dimensional duct flow computations for radial distributions of velocity, temperature, and electrical conductivity are reported. Calculations were carried out for the flow conditions representative of a hydrogen-oxygen combustion driven MHD duct. Results are presented for: profiles of developing flow in a smooth duct, and for profiles of fully developed pipe flow with a specified streamwise shear stress distribution. The predicted temperature and electrical conductivity profiles for the developing flows compare well with available experimental data.

  20. Comparison of Nerve Excitability Testing, Nerve Conduction Velocity, and Behavioral Observations for Acrylamide Induced Peripheral Neuropathy

    EPA Science Inventory

    Nerve excitability (NE) testing is a sensitive method to test for peripheral neurotoxicity in humans,and may be more sensitive than compound nerve action potential (CNAP) or nerve conduction velocity (NCV).We used acrylamide to compare the NE and CNAP/NCV methods. Behavioral test...

  1. Confirmation of Correlation between Brain Nerve Conduction Velocity and Intelligence Level in Normal Adults

    ERIC Educational Resources Information Center

    Reed, T. Edward; Vernon, Philip A.; Johnson, Andrew M.

    2004-01-01

    In 1992, Reed and Jensen ["Intelligence" 16 (1992) 259-272] reported a positive correlation (0.26; "p"= 0.002; 0.37 after correcting for restricted intelligence range) between a brain nerve conduction velocity (NCV) and intelligence level in 147 normal male students. In the first follow-up of their study, we report on a study…

  2. Preliminary Study on the Lesion Location and Prognosis of Cubital Tunnel Syndrome by Motor Nerve Conduction Studies

    PubMed Central

    Liu, Zhu; Jia, Zhi-Rong; Wang, Ting-Ting; Shi, Xin; Liang, Wei

    2015-01-01

    Background: To study lesions’ location and prognosis of cubital tunnel syndrome (CubTS) by routine motor nerve conduction studies (MNCSs) and short-segment nerve conduction studies (SSNCSs, inching test). Methods: Thirty healthy subjects were included and 60 ulnar nerves were studied by inching studies for normal values. Sixty-six patients who diagnosed CubTS clinically were performed bilaterally by routine MNCSs and SSNCSs. Follow-up for 1-year, the information of brief complaints, clinical symptoms, and physical examination were collected. Results: Sixty-six patients were included, 88 of nerves was abnormal by MNCS, while 105 was abnormal by the inching studies. Medial epicondyle to 2 cm above medial epicondyle is the most common segment to be detected abnormally (59.09%), P < 0.01. Twenty-two patients were followed-up, 17 patients’ symptoms were improved. Most of the patients were treated with drugs and modification of bad habits. Conclusions: (1) SSNCSs can detect lesions of compressive neuropathy in CubTS more precisely than the routine motor conduction studies. (2) SSNCSs can diagnose CubTS more sensitively than routine motor conduction studies. (3) In this study, we found that medial epicondyle to 2 cm above the medial epicondyle is the most vulnerable place that the ulnar nerve compressed. (4) The patients had a better prognosis who were abnormal in motor nerve conduction time only, but not amplitude in compressed lesions than those who were abnormal both in velocity and amplitude. Our study suggests that SSNCSs is a practical method in detecting ulnar nerve compressed neuropathy, and sensitive in diagnosing CubTS. The compound muscle action potentials by SSNCSs may predict prognosis of CubTS. PMID:25947398

  3. Techniques for automated local activation time annotation and conduction velocity estimation in cardiac mapping

    PubMed Central

    Cantwell, C.D.; Roney, C.H.; Ng, F.S.; Siggers, J.H.; Sherwin, S.J.; Peters, N.S.

    2015-01-01

    Measurements of cardiac conduction velocity provide valuable functional and structural insight into the initiation and perpetuation of cardiac arrhythmias, in both a clinical and laboratory context. The interpretation of activation wavefronts and their propagation can identify mechanistic properties of a broad range of electrophysiological pathologies. However, the sparsity, distribution and uncertainty of recorded data make accurate conduction velocity calculation difficult. A wide range of mathematical approaches have been proposed for addressing this challenge, often targeted towards specific data modalities, species or recording environments. Many of these algorithms require identification of activation times from electrogram recordings which themselves may have complex morphology or low signal-to-noise ratio. This paper surveys algorithms designed for identifying local activation times and computing conduction direction and speed. Their suitability for use in different recording contexts and applications is assessed. PMID:25978869

  4. Conduction velocities in amphibian skeletal muscle fibres exposed to hyperosmotic extracellular solutions.

    PubMed

    Chen, Zhongbo; Hothi, Sandeep S; Xu, Wei; Huang, Christopher L-H

    2007-01-01

    Early quantitative analyses of conduction velocities in unmyelinated nerve studied in a constantly iso-osmotic volume conductor were extended to an analysis of the effects of varying extracellular osmolarities on conduction velocities of surface membrane action potentials in Rana esculenta skeletal muscle fibres. Previous papers had reported that skeletal muscle fibres exposed to a wide range of extracellular sucrose concentrations resemble perfect osmometers with increased extracellular osmolarity proportionally decreasing fibre volume and therefore diminishing fibre radius, a. However, classical electrolyte theory (Robinson and Stokes 1959, Electrolyte solutions 2nd edn. Butterworth & Co. pp 41-42) would then predict that the consequent increases in intracellular ionic strength would correspondingly decrease sarcoplasmic resistivity, R(i). An extension of the original cable analysis then demonstrated that the latter would precisely offset its expected effect of alterations in a on the fibre axial resistance, r(i), and leave action potential conduction velocity constant. In contrast, other reports (Hodgkin and Nakajima J Physiol 221:105-120, 1972) had suggested that R(i) increased with extracellular osmolarity, owing to alterations in cytosolic viscosity. This led to a prediction of a decreased conduction velocity. These opposing hypotheses were then tested in muscle fibres subject to just-suprathreshold stimulation at a Vaseline seal at one end and measuring action potentials and their first order derivatives, dV/dt, using 5-20 MOmega, 3 M KCl glass microelectrodes at defined distances away from the stimulus sites. Exposures to hyperosmotic, sucrose-containing, Ringer solutions then reversibly reduced both conduction velocity and maximum values of dV/dt. This was compatible with an increase in R(i) in the event that conduction depended upon a discharge of membrane capacitance by propagating local circuit currents through initially passive electrical elements

  5. Influence of flow velocity on motor behavior of sea cucumber Apostichopus japonicus.

    PubMed

    Pan, Yang; Zhang, Libin; Lin, Chenggang; Sun, Jiamin; Kan, Rentao; Yang, Hongsheng

    2015-05-15

    The influence of flow velocity on the motor behavior of the sea cucumber, Apostichopus japonicus was investigated in the laboratory. Cameras were used to record sea cucumber movements and behavior analysis software was used to measure the distance traveled, time spent, upstream or downstream of the start position and the speed of movements. In general, the mean velocity of A. japonicus was below 0.7mms(-1). The maximum velocity recorded for all the sea cucumbers tested was for a large individual (89.25±17.11g), at a flow rate of 4.6±0.5cms(-1). Medium sized (19.68±5.53g) and large individuals moved significantly faster than small individuals (2.65±1.24g) at the same flow rate. A. japonicus moved significantly faster when there was a moderate current (4.6±0.5cms(-1) and 14.7±0.3cms(-1)), compared with the fast flow rate (29.3±3.7cms(-1)) and when there was no flow (0cms(-1)). Sea cucumbers did not show positive rheotaxis in general, but did move in a downstream direction at faster current speeds. Large, medium and small sized individuals moved downstream at the fastest current speed tested, 29.3±3.7cms(-1). When there was no water flow, sea cucumbers tended to move in an irregular pattern. The movement patterns show that the sea cucumber, A. japonicus can move across the direction of flow, and can move both upstream and downstream along the direction of flow.

  6. Quantum beats in conductance oscillations in graphene-based asymmetric double velocity wells and electrostatic wells

    SciTech Connect

    Liu, Lei; Li, Yu-Xian; Zhang, Ying-Tao; Liu, Jian-Jun

    2014-01-14

    The transport properties in graphene-based asymmetric double velocity well (Fermi velocity inside the well less than that outside the well) and electrostatic well structures are investigated using the transfer matrix method. The results show that quantum beats occur in the oscillations of the conductance for asymmetric double velocity wells. The beating effect can also be found in asymmetric double electrostatic wells, but only if the widths of the two wells are different. The beat frequency for the asymmetric double well is exactly equal to the frequency difference between the oscillation rates in two isolated single wells with the same structures as the individual wells in the double well structure. A qualitative interpretation is proposed based on the fact that the resonant levels depend upon the sizes of the quantum wells. The beating behavior can provide a new way to identify the symmetry of double well structures.

  7. Consideration of Conductive Motor Winding Materials at Room and Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    de Groh, Henry C., III

    2015-01-01

    A brief history of conductive motor winding materials is presented, comparing various metal motor winding materials and their properties in terms of conductivity, density and cost. The proposed use of carbon nanotubes (CNTs) and composites incorporating CNTs is explored as a potential way to improve motor winding conductivity, density, and reduce motor size which are important to electric aircraft technology. The conductivity of pure Cu, a CNT yarn, and a dilute Cu-CNT composite was measured at room temperature and at several temperatures up to 340 C. The conductivity of the Cu-CNT composite was about 3 percent lower than pure copper's at all temperatures measured. The conductivity of the CNT yarn was about 200 times lower than copper's, however, the yarn's conductivity dropped less with increasing temperature compared to Cu. It is believed that the low conductivity of the yarn is due primarily to high interfacial resistances and the presence of CNTs with low, semiconductor like electrical properties (s-CNT). It is believed the conductivity of the CNT-Cu composite could be improved by not using s-CNT, and instead using only CNTs with high, metallic like electrical properties (m-CNT); and by increasing the vol% m-CNTs.

  8. Synergistic plasticity of intrinsic conductance and electrical coupling restores synchrony in an intact motor network.

    PubMed

    Lane, Brian J; Samarth, Pranit; Ransdell, Joseph L; Nair, Satish S; Schulz, David J

    2016-08-23

    Motor neurons of the crustacean cardiac ganglion generate virtually identical, synchronized output despite the fact that each neuron uses distinct conductance magnitudes. As a result of this variability, manipulations that target ionic conductances have distinct effects on neurons within the same ganglion, disrupting synchronized motor neuron output that is necessary for proper cardiac function. We hypothesized that robustness in network output is accomplished via plasticity that counters such destabilizing influences. By blocking high-threshold K(+) conductances in motor neurons within the ongoing cardiac network, we discovered that compensation both resynchronized the network and helped restore excitability. Using model findings to guide experimentation, we determined that compensatory increases of both GA and electrical coupling restored function in the network. This is one of the first direct demonstrations of the physiological regulation of coupling conductance in a compensatory context, and of synergistic plasticity across cell- and network-level mechanisms in the restoration of output.

  9. Knee Muscle Strength at Varying Angular Velocities and Associations with Gross Motor Function in Ambulatory Children with Cerebral Palsy

    ERIC Educational Resources Information Center

    Hong, Wei-Hsien; Chen, Hseih-Ching; Shen, I-Hsuan; Chen, Chung-Yao; Chen, Chia-Ling; Chung, Chia-Ying

    2012-01-01

    The aim of this study was to evaluate the relationships of muscle strength at different angular velocities and gross motor functions in ambulatory children with cerebral palsy (CP). This study included 33 ambulatory children with spastic CP aged 6-15 years and 15 children with normal development. Children with CP were categorized into level I (n =…

  10. Comparisons of computed and measured three-dimensional velocity fields in a motored two-stroke engine

    SciTech Connect

    Amsden, A.A.; O'Rourke, P.J.; Butler, T.D. ); Meintjes, K.; Fansler, T.D. )

    1991-01-01

    Computer simulations are compared with measurements of the three-dimensional, unsteady scavenging flows of a motored two-stroke engine. Laser Doppler velocimetry measurements were made on a modified Suzuki DT-85 ported engine. Calculations were performed using KIVA-3, a computer program that efficiently solves the intake and exhaust port flows along with those in the cylinder. Measured and computed cylinder pressures and velocities are compared. Pressures agree well over the cycle as do the velocities at the intake ports. In-cylinder velocities differ in detail, but the tumbling motion in the cylinder is well replicated in vertical plane passing through the cylinder axis. 20 refs., 7 figs., 3 tabs.

  11. Conductivity, electric field and electron drift velocity within the equatorial electrojet

    NASA Astrophysics Data System (ADS)

    Rastogi, R. G.; Chandra, H.

    2006-08-01

    Rocket-borne in-situ measurements of electron density and current density made from Thumba, India, on four occasions between 1966 and 1973 and on one flight from Peru in 1965 are studied along with the corresponding ground magnetometer data. The Cowling conductivity is computed using the yearly mean magnetic field values of 1965 and the atmospheric density values from the MSIS 1986 model. The rocket-borne measurements from Thumba cover different geophysical conditions of strong, moderate and partial counter-electrojet events. The vertical profiles of the measured current density and electron density are presented along with the computed Cowling conductivity, electron drift velocity and electric field. The peak current density occurred at 106-107 km over Thumba and at 109 km over Peru compared to 104 km over Brazil. Cowling conductivity peaks occurred at 102 km over Huancayo and 101 km over Thumba, while electron drift velocity and electric field peaks occurred at approximately 105-107 km over Thumba, 108 and 110 km over Huancayo and 104 km over Brazil, respectively. While the electron density near the level of peak current density shows some variability, electron drift velocity and electric field show large variability. We conclude that the local electric field plays an important role in the spatial and temporal variability of the strength of the electrojet.

  12. Conduction velocities and membrane properties of different classes of rat septohippocampal neurons recorded in vitro

    PubMed Central

    Jones, Gareth A; Norris, Sarah K; Henderson, Zaineb

    1999-01-01

    The membrane properties and conduction velocities of antidromically activated medial septum-diagonal band (MS-DB) neurons were examined using whole-cell recordings in a longitudinally cut rat brain slice preparation containing the MS-DB and the dorsal fornix. MS-DB neurons were divided into three groups according to their action potential characteristics and firing properties. Slow firing neurons displayed a broad action potential followed by a prominent after-hyperpolarization. Burst firing neurons, when depolarized from hyperpolarized holding potentials, exhibited a high-frequency burst of spikes on the crest of a slow depolarizing potential. Fast firing neurons did not fire bursts of spikes when depolarized from hyperpolarized holding potentials. Eighteen MS-DB neurons were identified as septohippocampal by antidromic activation. Of the septohippocampal neurons, four were slow firing neurons, five were burst firing neurons and nine were fast firing neurons. The mean axon conduction velocities of these neurons fell into two significant groups, termed slow conducting and fast conducting. Slow firing septohippocampal neurons had significantly slower conduction velocities than either fast firing or burst firing neurons (P < 0.05), being 0.7 ± 0.5 ms−1 for slow firing neurons and 2.9 ± 2.0 and 2.0 ± 1.4 ms−1 for burst firing and fast firing neurons, respectively. On the basis of previous evidence which has linked firing properties with the neurochemical identities of the neurons, we propose that the slow firing septohippocampal neurons are cholinergic whereas the burst firing and fast firing septohippocampal neurons are GABAergic. PMID:10358125

  13. Knee muscle strength at varying angular velocities and associations with gross motor function in ambulatory children with cerebral palsy.

    PubMed

    Hong, Wei-Hsien; Chen, Hseih-Ching; Shen, I-Hsuan; Chen, Chung-Yao; Chen, Chia-Ling; Chung, Chia-Ying

    2012-01-01

    The aim of this study was to evaluate the relationships of muscle strength at different angular velocities and gross motor functions in ambulatory children with cerebral palsy (CP). This study included 33 ambulatory children with spastic CP aged 6-15 years and 15 children with normal development. Children with CP were categorized into level I (n=17) or level II (n=16) according to Gross Motor Function Classification System (GMFCS) levels. All children underwent curl-up test and isokinetic tests of the knee extensor and flexor muscle. Children with CP underwent the gross motor function assessments, including the Gross Motor Function Measure (GMFM-66) and the gross motor subtests of Bruininks-Oseretsky Test of Motor Proficiency (BOTMP). The hamstring-quadriceps ratio (HQ ratio) was calculated as 100%×(isokinetic peak torque of hamstring (knee flexor)/isokinetic peak torque of quadriceps (knee extensor)). Children with GMFCS level II had lower BOTMP and GMFM-66 scores, curl-up scores, HQ ratio, and knee muscle strength, especially knee flexor, compared to those with GMFCS level I. The regression analysis showed that knee flexor torques at 60 and 90°/s are mainly related to balance (r(2)=0.167, p=0.011) and strength (r(2)=0.243, p=0.002) while knee flexor torques at 120°/s mainly contribute to running speed and agility (r(2)=0.372, p<0.001). These findings suggest that children with CP had knee strength deficits, especially knee flexor. Postural muscle (knee flexor) strength dominated gross motor function than antigravity muscle strength (knee extensor). The knee flexor strength at different angular velocities was associated with various gross motor tasks. The HQ ratio may be used as a potential biomarker to probe the therapeutic effectiveness for muscle strengthening in these children. These data may allow clinician for formulating effective muscle strengthening strategies for these children.

  14. An Electromagnetic Gauge Technique for Measuring Shocked Particle Velocity in Electrically Conductive Samples

    NASA Astrophysics Data System (ADS)

    Cheng, David; Yoshinaka, Akio

    2014-10-01

    Electromagnetic velocity (EMV) gauges are a class of film gauges which permit the direct in-situ measurement of shocked material flow velocity. The active sensing element, typically a metallic foil, requires exposure to a known external magnetic field in order to produce motional electromotive force (emf). Due to signal distortion caused by mutual inductance between sample and EMV gauge, this technique is typically limited to shock waves in non-conductive materials. In conductive samples, motional emf generated in the EMV gauge has to be extracted from the measured signal which results from the combined effects of both motional emf and voltage changes from induced currents. An electromagnetic technique is presented which analytically models the dynamics of induced current between a copper disk moving as a rigid body with constant 1D translational velocity toward an EMV gauge, where both disk and gauge are exposed to a uniform external static magnetic field. The disk is modelled as a magnetic dipole loop where its Foucault current is evaluated from the characteristics of the fields, whereas the EMV gauge is modelled as a circuit loop immersed in the field of the magnetic dipole loop, the intensity of which is calculated as a function of space and, implicitly, time. Equations of mutual induction are derived and the current induced in the EMV gauge loop is solved, allowing discrimination of the motional emf. Numerical analysis is provided for the step response of the induced EMV gauge current with respect to the Foucault current in the moving copper sample.

  15. An Electromagnetic Gauge Technique for Measuring Shocked Particle Velocity in Electrically Conductive Samples

    NASA Astrophysics Data System (ADS)

    Cheng, David; Yoshinaka, Akio

    2014-11-01

    Electromagnetic velocity (EMV) gauges are a class of film gauges which permit the direct in-situ measurement of shocked material flow velocity. The active sensing element, typically a metallic foil, requires exposure to a known external magnetic field in order to produce motional electromotive force (emf). Due to signal distortion caused by mutual inductance between sample and EMV gauge, this technique is typically limited to shock waves in non-conductive materials. In conductive samples, motional emf generated in the EMV gauge has to be extracted from the measured signal which results from the combined effects of both motional emf and voltage changes from induced currents. An electromagnetic technique is presented which analytically models the dynamics of induced current between a copper disk moving as a rigid body with constant 1D translational velocity toward an EMV gauge, where both disk and gauge are exposed to a uniform external static magnetic field. The disk is modelled as a magnetic dipole loop where its Foucault current is evaluated from the characteristics of the fields, whereas the EMV gauge is modelled as a circuit loop immersed in the field of the magnetic dipole loop, the intensity of which is calculated as a function of space and, implicitly, time. Equations of mutual induction are derived and the current induced in the EMV gauge loop is solved, allowing discrimination of the motional emf. Numerical analysis is provided for the step response of the induced EMV gauge current with respect to the Foucault current in the moving copper sample.

  16. PIC Simulations of the Effect of Velocity Space Instabilities on Electron Viscosity and Thermal Conduction

    NASA Astrophysics Data System (ADS)

    Riquelme, Mario A.; Quataert, Eliot; Verscharen, Daniel

    2016-06-01

    In low-collisionality plasmas, velocity-space instabilities are a key mechanism providing an effective collisionality for the plasma. We use particle-in-cell (PIC) simulations to study the interplay between electron- and ion-scale velocity-space instabilities and their effect on electron pressure anisotropy, viscous heating, and thermal conduction. The adiabatic invariance of the magnetic moment in low-collisionality plasmas leads to pressure anisotropy, {{Δ }}{p}j\\equiv {p}\\perp ,j-{p}\\parallel ,j\\gt 0, if the magnetic field {\\boldsymbol{B}} is amplified ({p}\\perp ,j and {p}\\parallel ,j denote the pressure of species j (electron, ion) perpendicular and parallel to {\\boldsymbol{B}}). If the resulting anisotropy is large enough, it can in turn trigger small-scale plasma instabilities. Our PIC simulations explore the nonlinear regime of the mirror, IC, and electron whistler instabilities, through continuous amplification of the magnetic field | {\\boldsymbol{B}}| by an imposed shear in the plasma. In the regime 1≲ {β }j≲ 20 ({β }j\\equiv 8π {p}j/| {\\boldsymbol{B}}{| }2), the saturated electron pressure anisotropy, {{Δ }}{p}{{e}}/{p}\\parallel ,{{e}}, is determined mainly by the (electron-lengthscale) whistler marginal stability condition, with a modest factor of ˜1.5-2 decrease due to the trapping of electrons into ion-lengthscale mirrors. We explicitly calculate the mean free path of the electrons and ions along the mean magnetic field and provide a simple physical prescription for the mean free path and thermal conductivity in low-collisionality β j ≳ 1 plasmas. Our results imply that velocity-space instabilities likely decrease the thermal conductivity of plasma in the outer parts of massive, hot, galaxy clusters. We also discuss the implications of our results for electron heating and thermal conduction in low-collisionality accretion flows onto black holes, including Sgr A* in the Galactic Center.

  17. The electrical conductivity during incipient melting in the oceanic low velocity zone

    PubMed Central

    Sifré, David; Gardés, Emmanuel; Massuyeau, Malcolm; Hashim, Leila; Hier-Majumder, Saswata; Gaillard, Fabrice

    2014-01-01

    A low viscosity layer in the upper mantle, the Asthenosphere, is a requirement for plate tectonics1. The seismic low velocities and the high electrical conductivities of the Asthenosphere are attributed either to sub-solidus water-related defects in olivine minerals2-4 or to a few volume percents of partial melt5-8 but these two interpretations have shortcomings: (1) The amount of H2O stored in olivine is not expected to be higher than 50 ppm due to partitioning with other mantle phases9, including pargasite amphibole at moderate temperatures10, and partial melting at high temperatures9; (2) elevated melt volume fractions are impeded by the too cold temperatures prevailing in the Asthenosphere and by the high melt mobility that can lead to gravitational segregation11,12. Here we determined the electrical conductivity of CO2-H2O-rich melts, typically produced at the onset of mantle melting. Electrical conductivity modestly increases with moderate amounts of H2O and CO2 but it dramatically increases as CO2 content exceeds 6 wt% in the melt. Incipient melts, long-expected to prevail in the asthenosphere10,13-15, can therefore trigger its high electrical conductivities. Considering depleted and enriched mantle abundances in H2O and CO2 and their effect on the petrology of incipient melting, we calculated conductivity profiles across the Asthenosphere for various plate ages. Several electrical discontinuities are predicted and match geophysical observations in a consistent petrological and geochemical framework. In moderately aged plates (>5Ma), incipient melts most likely trigger both the seismic low velocities and the high electrical conductivities in the upper part of the asthenosphere, whereas for young plates4, where seamount volcanism occurs6, higher degree of melting is expected. PMID:24784219

  18. Electrical conductivity during incipient melting in the oceanic low-velocity zone.

    PubMed

    Sifré, David; Gardés, Emmanuel; Massuyeau, Malcolm; Hashim, Leila; Hier-Majumder, Saswata; Gaillard, Fabrice

    2014-05-01

    The low-viscosity layer in the upper mantle, the asthenosphere, is a requirement for plate tectonics. The seismic low velocities and the high electrical conductivities of the asthenosphere are attributed either to subsolidus, water-related defects in olivine minerals or to a few volume per cent of partial melt, but these two interpretations have two shortcomings. First, the amount of water stored in olivine is not expected to be higher than 50 parts per million owing to partitioning with other mantle phases (including pargasite amphibole at moderate temperatures) and partial melting at high temperatures. Second, elevated melt volume fractions are impeded by the temperatures prevailing in the asthenosphere, which are too low, and by the melt mobility, which is high and can lead to gravitational segregation. Here we determine the electrical conductivity of carbon-dioxide-rich and water-rich melts, typically produced at the onset of mantle melting. Electrical conductivity increases modestly with moderate amounts of water and carbon dioxide, but it increases drastically once the carbon dioxide content exceeds six weight per cent in the melt. Incipient melts, long-expected to prevail in the asthenosphere, can therefore produce high electrical conductivities there. Taking into account variable degrees of depletion of the mantle in water and carbon dioxide, and their effect on the petrology of incipient melting, we calculated conductivity profiles across the asthenosphere for various tectonic plate ages. Several electrical discontinuities are predicted and match geophysical observations in a consistent petrological and geochemical framework. In moderately aged plates (more than five million years old), incipient melts probably trigger both the seismic low velocities and the high electrical conductivities in the upper part of the asthenosphere, whereas in young plates, where seamount volcanism occurs, a higher degree of melting is expected.

  19. Tidal reversal and flow velocities using temperature and specific conductance in a small wetland creek

    NASA Astrophysics Data System (ADS)

    Eaton, Timothy T.

    2016-11-01

    Characterizing flow dynamics in very small tidal creeks is complicated and not well suited to methods developed for upland streams or coastal estuaries, due to low flows, bidirectionality and shallow waters. Simple instrumentation enables thermal and salinity signals to be used to observe flow directions and estimate velocities in these settings. Using multiple inexpensive sensors over 500 m along a tidally influenced wetland creek, I demonstrate how advection of temperature and specific conductance pulses reveal flood and ebb tides and the temporary reversal of flow by warmer, estuarine water from the receiving embayment. The sequential rise of temperature upstream was most evident under hot and dry conditions, after daily peak air temperatures of 25 °C or above, and was subdued or disrupted under cooler or rainy conditions in summertime. Changes in specific conductance at successive sites upstream were less susceptible to environmental influences and confirm tidal flood velocity of between 0.07 and 0.37 m/s. The tidally-induced flow reversal suggests that periodic high tide conditions can interfere with rapid dispersal of pollution discharges, such as from the combined sewer overflow (CSO) located upstream of the studied creek reach. This low-cost approach of temperature and specific conductance sensing in vegetated coastal wetlands where access, precise elevation control and creek discharge measurements are difficult, provides a simple way of tracking water masses when sufficient contrast exists between water sources.

  20. Mechanical muscle fibre conduction velocity of the biceps as measured by a new seismic technique.

    PubMed

    Journée, H L; de Jonge, A B; van Calker, R; Gräler, G

    1995-01-01

    A recently-developed technique, called seismic myography (SMG) has the characteristic of recording fast micro-mechanical response times. These times can be determined with sub-millisecond accuracy. The response times can be compared to response times of EMG recordings. The "muscular electro-seismic response" (MESR) latencies, due to direct electrical stimulation of the biceps muscle, are used for explorative measurements of the mechanical conduction velocity of the muscle fibres. The measurements are performed by means of a general-purpose physiological multimeter which is equiped with the micro-seismic function. Measurements are performed on two healthy subjects, aged 22 years. The MESR-latencies are measured along a medial and a lateral trajectory on their biceps muscles. The MESR-latencies at stimulus-cathodal to seismic transducer distances of 2,0-3,5 cm, are in the range of 2.0-3.8 ms, while at distances in the range of 7.5-8.9 cm the MESR-latencies varied between 3.4 and 4.7 ms. The calculated mechanical muscle fibre conduction velocities (MMFCV) are in the range between 36 and 89 m/s. There is a reproducability error of maximum 20%. The MMFCV's of the lateral and medial trajectory do not differ within the accuracy of the present method. However, the MMFCV's are considerably higher than the electrical muscle fibre conduction velocities of MUAPS ((E)MFCV). Some aspects of the MMFCV and possible consequences to surface EMG recordings are discussed. It is concluded that this seismic method for measuring MMFCV is a new accessible and simple to handle tool for the description of muscle function, and offers an interesting new contribution in experimental muscular research.

  1. Displacement of plasma protein and conduction velocity in rats under action of acceleration forces and hypokinesia

    NASA Technical Reports Server (NTRS)

    Baranski, S.; Edelwejn, Z.; Wojtkowiak, M.

    1980-01-01

    The permeability of capillary vessels was investigated in order to determine if acceleration alone or following prolonged hypokinesia would induce changes in the vascular wall leading to the penetration by l-albumins and/or proteins with larger molecules. In rats undergoing action of +5 Gz accelerations, no increase in vascular permeability, as tested with the use of (Cr-5k)-globulin, was demostrated. In rats immobilized for 4 weeks before centrifugation, rather weak migration of (Cr-51)-globulin from the vessels was observed. Immobilization resulted also in lowering of conduction velocity in the sciatic nerve.

  2. Comparison of Ear-Canal Reflectance and Umbo Velocity in Patients with Conductive Hearing Loss

    NASA Astrophysics Data System (ADS)

    Merchant, Gabrielle R.; Nakajima, Hideko H.; Pisano, Dominic V.; Röösli, Christof; Hamade, Mohamad A.; Mafoud, Lorice; Halpin, Christopher F.; Merchant, Saumil N.; Rosowski, John J.

    2011-11-01

    Patients who present at hearing clinics with a conductive hearing loss (CHL) in the presence of an intact, healthy tympanic membrane create a unique challenge for otologists. While patient counseling, treatment options, and outcome vary with differing middle-ear pathologies, a non-invasive diagnostic that can differentiate between these pathologies does not currently exist. We evaluated the clinical utility and diagnostic accuracy of two non-invasive measures of middle-ear mechanics: ear-canal reflectance (ECR) and umbo velocity (VU).

  3. Effects of the diacylglycerol complexing agent, cremophor, on nerve-conduction velocity and perfusion in diabetic rats.

    PubMed

    Jack, A M; Cameron, N E; Cotter, M A

    1999-01-01

    The contribution of diacylglycerol (DAG) and protein kinase C (PKC) to diabetic complications has been the subject of debate. In vascular tissues, diabetes increases DAG content, which activates PKC and causes abnormal tissue perfusion. Reduced nerve blood flow has been implicated in the development of neuropathy. However, nerve DAG/PKC activity is not increased and may even be reduced by diabetes, which has also been implicated in neuropathy. The aim was to test whether 2 weeks of treatment with cremophor, an agent that complexes DAG and prevents PKC activation, could correct nerve-conduction velocity (NCV) deficits in rats with 6 weeks of untreated diabetes, as predicted on a vascular hypothesis, or whether this worsened the deficits, as predicted for a direct effect on nerve fibers. Diabetes caused 17.9 +/- 0.9% (+/- SEM) and 15.5 +/- 1.6% reductions in sciatic motor and saphenous sensory NCV, respectively, that were largely (79.6 +/- 6.3% and 57.8 +/- 11.5%) corrected by 100 mg x kg(-1) x day(-1) cremophor treatment. The effects of cremophor on motor and sensory NCV were completely attenuated by co-treatment with the nitric oxide synthase inhibitor, N(G)-nitro-l-arginine. In contrast, co-treatment with the cyclooxygenase inhibitor, flurbiprofen, had no effect on NCV. Sciatic nutritive and total endoneurial perfusion were 49.7 +/- 3.4% and 51.8 +/- 4.2% reduced by diabetes, respectively, and these deficits were 69.5 +/- 7.4% and 79.0 +/- 11.6% corrected by cremophor treatment. Thus the data suggest that an increased DAG/PKC vascular mechanism, perhaps linked to the nitric oxide system, contributes to the etiology of diabetic nerve dysfunction.

  4. Effect of pioglitazone on nerve conduction velocity of the median nerve in the carpal tunnel in type 2 diabetes patients

    PubMed Central

    Chatterjee, Sudip; Sanyal, Debmalya; Das Choudhury, Sourav; Bandyopadhyay, Mili; Chakraborty, Suraj; Mukherjee, Arabinda

    2016-01-01

    AIM To evaluate the impact of pioglitazone pharmacotherapy in median nerve electrophysiology in the carpal tunnel among type 2 diabetes patients. METHODS The study was executed in patients with type 2 diabetes, treated with oral drugs, categorized under pioglitazone or non-pioglitazone group (14 in each group), and who received electrophysiological evaluation by nerve conduction velocity at baseline and 3 mo. RESULTS At 3 mo, pioglitazone-category had inferior amplitude in sensory median nerve [8.5 interquartile range (IQR) = 6.5 to 11.5) vs non-pioglitazone 14.5 (IQR 10.5 to 18.75)] (P = 0.002). Non-pioglitazone category displayed amelioration in amplitude in the sensory median nerve [baseline 13 (IQR = 9 to 16.25) vs 3 mo 8.5 (IQR = 6.5 to 11.5)] (P = 0.01) and amplitude in motor median nerve [baseline 9 (IQR = 4.75 to 11) vs 3 mo 6.75 (IQR = 4.75 to 10.25)] (P = 0.049); and deterioration of terminal latency of in motor ulnar nerve [baseline 2.07 (IQR = 1.92 to 2.25) vs 3 mo 2.16 (IQR = 1.97 to 2.325)] (P = 0.043). There was amelioration of terminal latency in sensory ulnar nerve [baseline 2.45 (IQR = 2.315 to 2.88) vs 3 mo 2.37 (IQR = 2.275 to 2.445) for pioglitazone group (P = 0.038). CONCLUSION Treatment with pioglitazone accentuates probability of compressive neuropathy. In spite of comparable glycemic control over 3 mo, patients treated with pioglitazone showed superior electrophysiological parameters for the ulnar nerve. Pioglitazone has favourable outcome in nerve electrophysiology which was repealed when the nerve was subjected to compressive neuropathy. PMID:27895823

  5. Synthesis of a correcting filter with phase stabilization of the angular velocity of a synchronous motor by the feedback system method

    NASA Technical Reports Server (NTRS)

    Kazlauskas, K. A.; Kurlavichus, A. I.

    1973-01-01

    The operating characteristics of a synchronous electric motor are discussed. A system of phase stabilization of the instantaneous angular velocity of rotation of a synchronous-reaction motor is diagrammed. A mathematical model is developed to show the parameters which affect the operation of the motor. The selection of a correcting filter to use with the motor in order to reduce the reaction of the system to interference is explained.

  6. Motor, Emotional, and Cognitive Empathy in Children and Adolescents with Autism Spectrum Disorder and Conduct Disorder

    ERIC Educational Resources Information Center

    Bons, Danielle; van den Broek, Egon; Scheepers, Floor; Herpers, Pierre; Rommelse, Nanda; Buitelaaar, Jan K.

    2013-01-01

    It is unclear which aspects of empathy are shared and which are uniquely affected in autism spectrum disorder (ASD) and conduct disorder (CD) as are the neurobiological correlates of these empathy impairments. The aim of this systematic review is to describe the overlap and specificity of motor, emotional, and cognitive aspects of empathy in…

  7. Prediction of rocks thermal conductivity from elastic wave velocities, mineralogy and microstructure

    NASA Astrophysics Data System (ADS)

    Pimienta, Lucas; Sarout, Joel; Esteban, Lionel; Piane, Claudio Delle

    2014-05-01

    While knowledge on Thermal Conductivity (TC) of rocks is of interest in many fields, determining this property remains challenging. In this paper, a modelling approach for TC prediction from Elastic Wave Velocity (EWV) measurements is reported. To this end, a new effective TC model for a typical sedimentary rock is introduced that explicitly accounts for the presence of pores, pressure-sensitive microcracks (or grain contacts) and formation fluids. A model of effective elasticity is also devised for this same rock that links its microstructural characteristics to the velocity of elastic waves. The two models are based on the same effective medium approach and involve the same microstructural parameters. A workflow based on this explicit modelling approach is devised that allows for the prediction of the TC of a reservoir rock using (i) the elastic waves velocities, (ii) the dominant mineral content and (iii) the bulk porosity. This workflow is validated using experimental data reported in the literature for dry and water-saturated Fontainebleau and Berea sandstones. The datasets include measurements of TC and EWV as a function of effective pressure. In addition, it is shown that the dependence of TC on the rock microstructure is formally and practically similar to that of EWV. It is also demonstrated that the accuracy of TC predictions from EWV increases with effective pressure (burial depth). The underlying assumptions and limitations of the present approach together with the effect of burial are discussed.

  8. Muscle-fiber conduction velocity during concentric and eccentric actions on a flywheel exercise device.

    PubMed

    Pozzo, Marco; Alkner, Björn; Norrbrand, Lena; Farina, Dario; Tesch, Per A

    2006-08-01

    A gravity-independent flywheel exercise device (FWED) has been proven effective as a countermeasure to loss of strength and muscle atrophy induced by simulated microgravity. This study assessed muscle-fiber conduction velocity (CV) and surface EMG instantaneous mean power spectral frequency (iMNF) during brief bouts of fatiguing concentric (CON) and eccentric (ECC) exercise on a FWED in order to identify electromyographic (EMG) variables that can be used to provide objective indications of muscle status when exercising with a FWED. Multichannel surface EMG signals were recorded from vastus lateralis and medialis muscles of nine men during: (1) isometric, 60-s action at 50% of maximum voluntary action (MVC); (2) two isometric, linearly increasing force ramps (0-100% MVC); and (3) dynamic CON/ECC coupled actions on the FWED. Muscle-fiber CV and iMNF were computed over time during the three tasks. During ramps, CV, but not iMNF, increased with force (P < 0.001). Conduction velocity and iMNF decreased with the same normalized rate of change in constant-force actions. During CON/ECC actions, the normalized rate of change over time was larger for CV than iMNF (P < 0.05). These results suggest that, during fatiguing, dynamic, variable-force tasks, changes in CV cannot be indirectly inferred by EMG spectral analysis. This underlines the importance of measuring both CV and spectral variables for muscle assessment in dynamic tasks.

  9. [Physiological approach to peripheral neuropathy. Conventional nerve conduction studies and magnetic motor root stimulation].

    PubMed

    Ugawa, Yoshikazu

    2004-11-01

    In this communication, I first show some points we should mind in the conventional peripheral nerve conduction studies and later present clinical usefulness of motor root stimulation for peripheral neuropathy. CONVENTIONAL NERVE CONDUCTION STUDIES (NCS): The most important point revealed by the conventional NCSs is whether neuropathy is due to axonal degeneration or demyelinating process. Precise clinical examination with this neurophysiological information leads us to a diagnosis and treatment. Poor clinical examination makes these findings useless. Long standing axonal degeneration sometimes induces secondary demyelination at the most distal part of involved nerves. On the other hand, severe segmental demyelination often provokes secondary axonal degeneration at distal parts to the site of demyelination. These secondary changes show the same abnormal neurophysiological findings as those of the primary involvement. We should be careful of this possibility when interpreting the results of NCS. NCS of sensory nerves is not good at revealing demyelinating process. Mild temporal dispersion of potentials often reduces an amplitude of SNAP or loss of responses, which usually suggests axonal degeneration, because of short duration of sensory nerve potentials. MOTOR ROOT STIMULATION IN PERIPHERAL NEUROPATHY: Magnetic stimulation with a coil placed over the spine activates motor roots and evokes EMG responses from upper and lower limb muscles. The site of activation with this method was determined to be where the motor roots exit from the spinal canal (intervertebral foramina) (J Neurol Neurosurg Psychiatry 52 (9): 1025-1032, 1989) because induced currents are very dense at such a foramen made by electric resistant bones. In several kinds of peripheral neuropathy, this method has been used to detect a lesion at a proximal part of the peripheral nerves which can not be detected by the conventional NCSs. I present a few cases in whom motor root stimulation had a clinical

  10. Relationship of neonatal cerebral blood flow velocity asymmetry with early motor, cognitive and language development in term infants.

    PubMed

    Wu, Ying-Chin; Hsieh, Wu-Shiun; Hsu, Chyong-Hsin; Chiu, Nan-Chang; Chou, Hung-Chieh; Chen, Chien-Yi; Peng, Shinn-Forng; Hung, Han-Yang; Chang, Jui-Hsing; Chen, Wei J; Jeng, Suh-Fang

    2013-05-01

    The objective of this study was to examine the relationships of Doppler cerebral blood flow velocity (CBFV) asymmetry measures with developmental outcomes in term infants. Doppler CBFV parameters (peak systolic velocity [PSV] and mean velocity [MV]) of the bilateral middle cerebral arteries of 52 healthy term infants were prospectively examined on postnatal days 1-5, and then their motor, cognitive and language development was evaluated with the Bayley Scales of Infant and Toddler Development, Third Edition, at 6, 12, 18 and 24 months of age. The left CBFV asymmetry measure (PSV or MV) was calculated by subtracting the right-side value from the left-side value. Left CBFV asymmetry measures were significantly positively related to motor scores at 6 (r = 0.3-0.32, p < 0.05) and 12 (r = 0.35, p < 0.05) months of age, but were not related to cognitive or language outcome. Thus, the leftward hemodynamic status of the middle cerebral arteries, as measured by cranial Doppler ultrasound in the neonatal period, predicts early motor outcome in term infants.

  11. Cat hindlimb motoneurons during locomotion. I. Destination, axonal conduction velocity, and recruitment threshold.

    PubMed

    Hoffer, J A; Loeb, G E; Marks, W B; O'Donovan, M J; Pratt, C A; Sugano, N

    1987-02-01

    Fine flexible wire microelectrodes chronically implanted in the fifth lumbar ventral root (L5 VR) of 17 cats rendered stable records of the natural discharge patterns of 164 individual axons during locomotion on a treadmill. Fifty-one out of 164 axons were identified as motoneurons projecting to the anterior thigh muscle group. For these axons, the centrifugal propagation of action potentials was demonstrated by the technique of spike-triggered averaging using signals recorded from cuff electrodes implanted around the femoral nerve. The axonal conduction velocity was measured from the femoral nerve cuff records. For 43/51 motoneurons, the corresponding target muscle was identified by spike-triggered averaging of signals recorded from bipolar EMG electrodes implanted in each of the anterior thigh muscles: vastus intermedius, medialis and lateralis, sartorius anterior and medialis, and rectus femoris. For 32/51 motoneurons, the recruitment threshold during locomotion was determined from the mean value of the rectified digitally smoothed EMG of the target muscle measured at the time when the motoneuron fired its first spike for each step. The recruitment threshold of every motoneuron was relatively constant for a given speed of walking, but for some units there were small systematic variations as a function of treadmill speed (range: 0.1-1.3 m/s). Recruitment thresholds were standardized with respect to the mean value of peak EMG activity of the target muscle during 16 s of walking at 0.5 m/s. For 28/51 motoneurons recorded in nine cats, recruitment thresholds (range: 3-93% of peak target muscle EMG) were linearly correlated (r = 0.51, P less than 0.02) to axonal conduction velocities (range: 57-117 m/s). In addition, for seven recorded pairs of motoneurons that projected to the same muscle in the same cat, the recruitment thresholds were ordered by relative conduction velocities. Taken together, these results are consistent with the notion that, in normal cat

  12. Noninvasive Peroneal Sensory and Motor Nerve Conduction Recordings in the Rabbit Distal Hindlimb: Feasibility, Variability and Neuropathy Measure

    PubMed Central

    Hotson, John R.

    2014-01-01

    The peroneal nerve anatomy of the rabbit distal hindlimb is similar to humans, but reports of distal peroneal nerve conduction studies were not identified with a literature search. Distal sensorimotor recordings may be useful for studying rabbit models of length-dependent peripheral neuropathy. Surface electrodes were adhered to the dorsal rabbit foot overlying the extensor digitorum brevis muscle and the superficial peroneal nerve. The deep and superficial peroneal nerves were stimulated above the ankle and the common peroneal nerve was stimulated at the knee. The nerve conduction studies were repeated twice with a one-week intertest interval to determine measurement variability. Intravenous vincristine was used to produce a peripheral neuropathy. Repeat recordings measured the response to vincristine. A compound muscle action potential and a sensory nerve action potential were evoked in all rabbits. The compound muscle action potential mean amplitude was 0.29 mV (SD ± 0.12) and the fibula head to ankle mean motor conduction velocity was 46.5 m/s (SD ± 2.9). The sensory nerve action potential mean amplitude was 22.8 μV (SD ± 2.8) and the distal sensory conduction velocity was 38.8 m/s (SD ± 2.2). Sensorimotor latencies and velocities were least variable between two test sessions (coefficient of variation  =  2.6–5.9%), sensory potential amplitudes were intermediate (coefficient of variation  =  11.1%) and compound potential amplitudes were the most variable (coefficient of variation  = 19.3%). Vincristine abolished compound muscle action potentials and reduced sensory nerve action potential amplitudes by 42–57% while having little effect on velocity. Rabbit distal hindlimb nerve conduction studies are feasible with surface recordings and stimulation. The evoked distal sensory potentials have amplitudes, configurations and recording techniques that are similar to humans and may be valuable for measuring large sensory fiber function in chronic

  13. Ultrafast Optical Measurements of Thermal Conductivity and Sound Velocity of Amorphous SiC

    NASA Astrophysics Data System (ADS)

    Hondongwa, Donald; Olasov, Lauren; Daly, Brian; King, Sean; Bielefeld, Jeff

    2011-03-01

    We present ultrafast optical measurements of longitudinal sound velocity and thermal transport in hydrogenated amorphous carbon (a-SiC:H) films. The films were grown on Si wafers by PECVD using combinations of methylsilanes and H2 and He diluent gases. The films were well characterized and found to have densities (1.0 -- 2.5 g cm-3) and dielectric constants (2.8 -- 7.2) that spanned a wide range of values. Prior to their measurement, the a-SiC:H films were coated with 40-70 nm of polycrystalline Al. The pump-probe measurements were performed at room temperature using a modelocked Ti:sapphire laser. Transient reflectivity changes that are associated with very high frequency sound waves (picosecond ultrasonics) and the cooling rate of the SiC sample (Time Domain Thermorerflectance (TDTR)) were measured. We extract values for the thermal conductivity and sound velocity of the SiC films, and analyze the results in terms of rigidity percolation effects within the SiC layers. This work was supported by NSF award DMR-0906753.

  14. Synergistic plasticity of intrinsic conductance and electrical coupling restores synchrony in an intact motor network

    PubMed Central

    Lane, Brian J; Samarth, Pranit; Ransdell, Joseph L; Nair, Satish S; Schulz, David J

    2016-01-01

    Motor neurons of the crustacean cardiac ganglion generate virtually identical, synchronized output despite the fact that each neuron uses distinct conductance magnitudes. As a result of this variability, manipulations that target ionic conductances have distinct effects on neurons within the same ganglion, disrupting synchronized motor neuron output that is necessary for proper cardiac function. We hypothesized that robustness in network output is accomplished via plasticity that counters such destabilizing influences. By blocking high-threshold K+ conductances in motor neurons within the ongoing cardiac network, we discovered that compensation both resynchronized the network and helped restore excitability. Using model findings to guide experimentation, we determined that compensatory increases of both GA and electrical coupling restored function in the network. This is one of the first direct demonstrations of the physiological regulation of coupling conductance in a compensatory context, and of synergistic plasticity across cell- and network-level mechanisms in the restoration of output. DOI: http://dx.doi.org/10.7554/eLife.16879.001 PMID:27552052

  15. Acute Motor Conduction Block Neuropathy: Another Distinct Variant of Guillain-Barre Syndrome

    PubMed Central

    ERDOĞMUŞ İNCE, Nilüfer; ÖZTEKİN, M. Fevzi; ÖZTEKİN, Neşe

    2014-01-01

    We describe a patient who developed progressive weakness in all limbs without sensory symptoms 4 weeks after upper respiratory system infection. Electrophysiological findings suggested a new variant of Guillain-Barré syndrome named “acute motor conduction block neuropathy”. Electrophysiological studies were performed at admission, 12th and 28th weeks. At the 28th week, the clinical examination and electrophysiological findings showed complete recovery.

  16. Harmonic force spectroscopy reveals a force-velocity curve from a single human beta cardiac myosin motor

    NASA Astrophysics Data System (ADS)

    Sung, Jongmin; Nag, Suman; Vestergaard, Christian; Mortensen, Kim; Flyvbjerg, Henrik; Spudich, James

    2014-03-01

    A muscle contracts rapidly under low load, but slowly under high load. Its molecular mechanisms remain to be elucidated, however. During contraction, myosins in thick filaments interact with actin in thin filaments in the sarcomere, cycling between a strongly bound (force producing) state and a weakly bound (relaxed) state. Huxley et al. have previously proposed that the transition from the strong to the weak interaction can be modulated by a load. We use a new method we call ``harmonic force spectroscopy'' to extract a load-velocity curve from a single human beta cardiac myosin II motor. With a dual-beam optical trap, we hold an actin dumbbell over a myosin molecule anchored to the microscope stage that oscillates sinusoidally. Upon binding, the motor experiences an oscillatory load with a mean that is directed forward or backward, depending on binding location We find that the bound time at saturating [ATP] is exponentially correlated with the mean load, which is explained by Arrhenius transition theory. With a stroke size measurement, we obtained a load-velocity curve from a single myosin. We compare the curves for wild-type motors with mutants that cause hypertrophic cardiomyopathies, to understand the effects on the contractile cycle

  17. Alterations of cortical excitability and central motor conduction time in Wilson's disease.

    PubMed

    Jhunjhunwala, Ketan; Prashanth, D K; Netravathi, M; Nagaraju, B C; Pal, Pramod Kr

    2013-10-11

    Wilson's disease (WD) leads to widespread structural alterations of central nervous system and our objectives were to determine the cortical excitability changes in WD by using transcranial magnetic stimulation (TMS). Thirteen patients with WD, diagnosed by the presence of Kayser-Fleischer ring and biochemical tests, were studied. TMS was performed using a figure-of-eight coil attached to Magstim 200 stimulator. Motor evoked potentials (MEP) were recorded from right first dorsal interosseous at rest. Resting motor threshold (RMT) was determined using standard techniques and central motor conduction time (CMCT) by 'F' wave method. Comparison was made with control data of our laboratory. Dysarthria was the presenting symptom in 5 patients (38.5%) and chorea, tremors, dystonia and abnormal gait in 2 patients each (15.4%). RMT was recordable in 10 patients and not recordable in 3. Compared to controls, patients in whom RMT was recordable, had significantly higher mean RMT (80.9 ± 14.8 vs. 41.1 ± 7, p<0.0001) and CMCT (6.7 ± 0.5 ms vs. 4.8 ± 0.6 ms; p<0.0001). In 2 of the 3 patients with non-recordable RMT, MEP could be obtained with active contraction. CMCT in these 2 patients was also prolonged. Patients with WD have reduced cortical excitability and prolonged CMCT which may be due to the intracortical presynaptic motor dysfunction.

  18. The electrical conductivity during incipient melting in the oceanic low velocity zone

    NASA Astrophysics Data System (ADS)

    Gaillard, Fabrice; Sifre, David; Gardes, Emmanuel; Massuyeau, Malcolm; Hashim, Leila; Hier Majumder, Saswata

    2014-05-01

    A low viscosity layer at the Lithosphere-Asthenosphere Boundary (LAB) is certainly a requirement for plate tectonics but the nature of the rocks presents in this boundary remains controversial. The seismic low velocities and the high electrical conductivities of the LAB are attributed either to sub-solidus water-related defects in olivine minerals or to a few volume percents of partial melt but these two interpretations have shortcomings: (1) The amount of H2O stored in olivine is not expected to be high enough due to several mineralogical processes that have been sometimes ignored; (2) elevated melt volume fractions are impeded by the too cold temperatures prevailing in the LAB and by the high melt mobility that can lead to gravitational segregation. All this has in fact been partly settled 30 years ago, when a petrological LAB has been defined as a region of the upper mantle impregnated by incipient melts; that is small amounts of melt caused by small amount of CO2 and H2O. We show here that incipient melting is a melting regime that is allowed in the entire P-T-fO2 region of the LVZ. The top of the oceanic LVZ (LAB) is then best explained by a melt freezing layer due to a decarbonation reaction, whereas the bottom of the LVZ matches the depth at which redox melting defines the lower boundary of stability of incipient melts. Based on new laboratory measurements, we show here that incipient melts must be the cause of the high electrical conductivities in the oceanic LVZ. Considering relevant mantle abundances of H2O and CO2 and their effect on the petrology of incipient melting, we calculated conductivity profiles across the LAB for various ages. Several electrical discontinuities are predicted and match geophysical observations in a consistent petrological and geochemical framework. We conclude that incipient melts prevail in the LAB, what else?

  19. Low-Cost Timer to Measure the Terminal Velocity of a Magnet Falling through a Conducting Pipe

    ERIC Educational Resources Information Center

    Pathare, Shirish R.; Huli, Saurabhee; Lahane, Rohan; Sawant, Sumedh

    2014-01-01

    Dropping a magnet into a conductive pipe (made up of copper or brass or aluminum) is a very popular demonstration in many physics classrooms and laboratories. In this paper we present an inexpensive timer that can be used to measure the terminal velocity of the magnet falling through a conducting pipe. The timer assembly consists of Hall effect…

  20. Analysis of of Injection-Velocity Effects on Rocket Motor Dynamics and Stability

    NASA Technical Reports Server (NTRS)

    Hurrell, Herbert G.

    1959-01-01

    A concept of combustion time lag that includes dependency on injection velocity is introduced. The concept is used in the formulation of chamber transfer functions and in an analysis of low-frequency combustion instability. Theoretical frequency responses and stability boundaries are compared with those obtained when the injection-velocity effect on the time lag to be an important consideration, in the theory of chamber dynamics and combustion instability

  1. Muscle conduction velocity, strength, neural activity, and morphological changes after eccentric and concentric training.

    PubMed

    Cadore, E L; González-Izal, M; Pallarés, J G; Rodriguez-Falces, J; Häkkinen, K; Kraemer, W J; Pinto, R S; Izquierdo, M

    2014-10-01

    This study compared the effects of concentric and eccentric training on neuromuscular adaptations in young subjects. Twenty-two men and women were assigned to one of two groups: concentric (CON, n = 11) and eccentric (ECC, n = 11) training. Training consisted of 6 weeks of isokinetic exercise, performed twice weekly, starting with two sets of eight repetitions, and progressing to five sets of 10 repetitions. Subjects were tested in strength variables [concentric, eccentric, and isometric peak torque (PT), and rate of force development (RFD)], muscle conduction velocity (CV), neuromuscular activity, vastus lateralis (VL) muscle thickness, and echo intensity as determined by ultrasonography. There were similar increases in the concentric and eccentric PTs in both the CON and ECC groups (P < 0.01), but only the ECC group showed an increase in isometric PT (P < 0.001). Similarly, both groups exhibited increased VL muscle thickness, CV, and RFD, and reduced VL echo intensity (P < 0.05). Significant correlations were observed among the relative changes in the neuromuscular outcomes and training variables (e.g., total work, average PT) (r = 0.68-0.75, P < 0.05). The results showed that both training types similarly improved dynamic PT, CV, RFD, and muscle thickness and quality during the early weeks of training.

  2. Towards Real-Time Estimation of Muscle-Fiber Conduction Velocity using Delay-Locked Loop.

    PubMed

    Xu, Lin; Rabotti, Chiara; Mischi, Massimo

    2016-11-24

    Decrease in muscle-fiber conduction velocity (MFCV) during sustained contraction has been widely accepted as myoelectric manifestation of muscle fatigue. Several methods have been proposed in the literature for MFCV estimation by analysing surface electromyography (EMG), e.g., cross-correlation (CC) function and maximum likelihood (ML). However, for all the available methods, windowing of the EMG signal and computationally demanding calculations are required, limiting the possibility to continuously monitor muscle fatigue in real time. In the present study, an adaptive scheme is proposed that permits real-time estimation of MFCV. The proposed scheme is based on a delay-locked loop (DLL). A second-order loop is adopted to track the delay variation over time. An error filter is employed to approximate a ML estimation in case of colored noise. Furthermore, the DLL system is extended for multichannel CV estimation. The performance of the proposed method is evaluated by both dedicated simulations and real EMG signals. Our results show the accuracy of the proposed method to be comparable to that of the ML method for much lower (1/40) computational complexity, especially suited for real-time MFCV measurements. Use of this method can enable new studies on myoelectric fatigue, possibly leading to new insight on the underlying physiological processes.

  3. Relationship between innervation zone width and mean muscle fiber conduction velocity during a sustained isometric contraction

    PubMed Central

    Ye, X.; Beck, T.W.; Wages, N.P.

    2015-01-01

    Objectives: To examine the relationship between the biceps brachii muscle innervation zone (IZ) width and the mean muscle fiber conduction velocity (MFCV) during a sustained isometric contraction. Methods: Fifteen healthy men performed a sustained isometric elbow flexion exercise at their 60% maximal voluntary contraction (MVC) until they could not maintain the target force. Mean MFCV was estimated through multichannel surface electromyographic recordings from a linear electrode array. Before exercise, IZ width was quantified. Separate non-parametric one-way analyses of variance (ANOVAs) were used to examine whether there was a difference in each mean MFCV variable among groups with different IZ width. In addition, separate bivariate correlations were also performed to examine the relationships between the IZ width and the mean MFCV variables during the fatiguing exercise. Results: There was a significant difference in the percent decline of mean MFCV (%ΔMFCV) among groups with different IZ width (χ2 (3)=11.571, p=0.009). In addition, there was also a significant positive relationship between the IZ width and the %ΔMFCV (Kendall’s tau= 0.807; p<0.001). Conclusions: We believe that such relationship is likely influenced by both muscle fiber size and the muscle fiber type composition. PMID:25730657

  4. Effects of muscle fiber type and size on EMG median frequency and conduction velocity.

    PubMed

    Kupa, E J; Roy, S H; Kandarian, S C; De Luca, C J

    1995-07-01

    This paper describes an in vitro method for comparing surface-detected electromyographic median frequency (MF) and conduction velocity (CV) parameters with histochemical measurements of muscle fiber type composition and cross-sectional area (CSA). Electromyographic signals were recorded during electrically elicited tetanic contractions from rat soleus, extensor digitorum longus, and diaphragm muscles placed in an oxygenated Krebs bath. Fibers were typed as slow oxidative, fast oxidative glycolytic, and fast glycolytic based on histochemical enzyme stains. Muscles with a greater percentage of fast glycolytic and fast oxidative glycolytic fibers exhibited greater initial values of MF and CV as well as a greater reduction in these variables over the course of the contraction. Regression indicated that fiber type composition could be predicted based on two MF parameters. A weighted measure of muscle fiber CSA was found to be linearly related to both initial MF and CV. The results of this study suggest that MF and CV parameters recorded during a muscular contraction are related to muscle fiber type composition and muscle fiber CSA.

  5. Decrease of muscle fiber conduction velocity correlates with strength loss after an endurance run.

    PubMed

    Boccia, Gennaro; Dardanello, Davide; Tarperi, Cantor; Rosso, Valeria; Festa, Luca; La Torre, Antonio; Pellegrini, Barbara; Schena, Federico; Rainoldi, Alberto

    2017-02-01

    Monitoring surface electromyographic (EMG) signals can provide useful insights for characterizing muscle fatigue, which is defined as an exercise-induced strength loss. This experiment investigated the muscle fiber conduction velocity (CV) changes induced by an endurance run. The day before and immediately after a half-marathon run (21.097 km) 11 amateur runners performed maximum voluntary contractions (MVCs) of knee extensor muscles. During the MVC, multichannel EMG was recorded from the vastus lateralis and EMG amplitude and CV were calculated. After the run, knee extensors showed a decreased strength (-13  ±  9%, p  =  0.001) together with a reduction in EMG amplitude (-13  ±  10%, p  =  0.003) and in CV (-6  ±  8%, p  =  0.032). Knee extensor strength loss positively correlated with vastus lateralis CV differences (r  =  0.76, p  =  0.006). Thus, the exercises-induced muscle fatigue was associated not only with a decrease in EMG amplitude, but also with a reduction in CV. This finding suggests that muscle fibers with higher CV (i.e. those with greater fiber size) were the most impaired during strength production after an endurance run.

  6. Relation between muscle fiber conduction velocity and exerted dynamic characteristics of muscular tension in patients with hemiplegia caused by stroke

    PubMed Central

    Murakami, Kenichi; Fujisawa, Hiroyuki; Suzuki, Makoto; Sato, Yoichiro; Sakurai, Kentaro; Abe, Chie

    2016-01-01

    [Purpose] The aim of this study was to clarify the relationships among muscle fiber conduction velocity, time-force characteristics of muscle force production, and voluntary movement in patients with hemiplegia. [Subjects and Methods] The participants in the present study were 13 patients with hemiplegia. Muscle fiber conduction velocity, deep temperature of muscles and muscle thickness were measured for the tibialis anterior, and a time force curve was obtained from dorsiflexion of the ankle and lower thigh girth (maximum, minimum) for both sides. The maximum torque rate of change and maximum torque were calculated from the force-time curve. In addition, Brunnstrom Recovery Stage was used to evaluate the function of the hemiplegic side. [Results] In all the measurement items, significant differences were observed between the hemiplegic side and the healthy side. The maximum torque rate of change and Brunnstrom Recovery Stage showed a high degree of correlation. The muscle fiber conduction velocity and maximum torque rate of change or maximum torque showed a medium degree of correlation. However, muscle fiber conduction velocity was not significantly correlated with Brunnstrom Recovery Stage. [Conclusion] Brunnstrom Recovery Stage was good as a determination factor for the maximum torque rate of change. In addition, in patients with hemiplegia, it became clear that relationship is between muscle fiber conduction velocity and time-force characteristics of muscle force production as in healthy persons. PMID:27821946

  7. Relation between muscle fiber conduction velocity and exerted dynamic characteristics of muscular tension in patients with hemiplegia caused by stroke.

    PubMed

    Murakami, Kenichi; Fujisawa, Hiroyuki; Suzuki, Makoto; Sato, Yoichiro; Sakurai, Kentaro; Abe, Chie

    2016-10-01

    [Purpose] The aim of this study was to clarify the relationships among muscle fiber conduction velocity, time-force characteristics of muscle force production, and voluntary movement in patients with hemiplegia. [Subjects and Methods] The participants in the present study were 13 patients with hemiplegia. Muscle fiber conduction velocity, deep temperature of muscles and muscle thickness were measured for the tibialis anterior, and a time force curve was obtained from dorsiflexion of the ankle and lower thigh girth (maximum, minimum) for both sides. The maximum torque rate of change and maximum torque were calculated from the force-time curve. In addition, Brunnstrom Recovery Stage was used to evaluate the function of the hemiplegic side. [Results] In all the measurement items, significant differences were observed between the hemiplegic side and the healthy side. The maximum torque rate of change and Brunnstrom Recovery Stage showed a high degree of correlation. The muscle fiber conduction velocity and maximum torque rate of change or maximum torque showed a medium degree of correlation. However, muscle fiber conduction velocity was not significantly correlated with Brunnstrom Recovery Stage. [Conclusion] Brunnstrom Recovery Stage was good as a determination factor for the maximum torque rate of change. In addition, in patients with hemiplegia, it became clear that relationship is between muscle fiber conduction velocity and time-force characteristics of muscle force production as in healthy persons.

  8. A new method to measure caudal motor conduction time using magnetic stimulation.

    PubMed

    Han, Tai Ryoon; Paik, Nam Jong; Lee, Seong Jae; Kwon, Bum Sun

    2004-12-01

    Although central motor conduction time (CMCT) has been used for the diagnosis of lumbosacral spinal stenosis (LSSS), its diagnostic value is limited due to the short length of the involved segment compared to the long length of the total conduction distance. To overcome this, we introduce a new method to measure the caudal motor conduction time (caudal MCT) using magnetic stimulation. Magnetic stimulation was applied to the vertex and the T12 and S1 spinous processes for transcortical, thoracic, and sacral stimulation, respectively, and compound muscle action potentials were recorded simultaneously from the rectus abdominis (RA) and the right and left abductor hallucis (AH) muscles using three channels. CMCT was calculated by the latency difference in the AH response between transcortical and sacral stimulation, and between transcortical and thoracic stimulation for RA. Caudal MCT was calculated by subtracting CMCT for RA from that for AH. Caudal MCT was delayed in patients with LSSS compared to normal persons. We suggest that measuring caudal MCT may be useful for the diagnosis of LSSS, but its diagnostic sensitivity and specificity requires prospective study.

  9. Motor, emotional, and cognitive empathy in children and adolescents with autism spectrum disorder and conduct disorder.

    PubMed

    Bons, Danielle; van den Broek, Egon; Scheepers, Floor; Herpers, Pierre; Rommelse, Nanda; Buitelaar, Jan K; Buitelaaar, Jan K

    2013-04-01

    It is unclear which aspects of empathy are shared and which are uniquely affected in autism spectrum disorder (ASD) and conduct disorder (CD) as are the neurobiological correlates of these empathy impairments. The aim of this systematic review is to describe the overlap and specificity of motor, emotional, and cognitive aspects of empathy in children and adolescents with ASD or CD. Motor and cognitive empathy impairments are found in both ASD and CD, yet the specificity seems to differ. In ASD facial mimicry and emotion recognition may be impaired for all basic emotions, whereas in CD this is only the case for negative emotions. Emotional empathy and the role of attention to the eyes therein need further investigation. We hypothesize that impaired motor and cognitive empathy in both disorders are a consequence of lack of attention to the eyes. However, we hypothesize major differences in emotional empathy deficits between ASD and CD, probably due to emotional autonomic and amygdala hyper-responsivity in ASD versus hypo-responsivity in CD, both resulting in lack of attention to the eyes.

  10. Extracellular sodium dependence of the conduction velocity-calcium relationship: evidence of ephaptic self-attenuation.

    PubMed

    George, Sharon A; Bonakdar, Mohammad; Zeitz, Michael; Davalos, Rafael V; Smyth, James W; Poelzing, Steven

    2016-05-01

    Our laboratory previously demonstrated that perfusate sodium and potassium concentrations can modulate cardiac conduction velocity (CV) consistent with theoretical predictions of ephaptic coupling (EpC). EpC depends on the ionic currents and intercellular separation in sodium channel rich intercalated disk microdomains like the perinexus. We suggested that perinexal width (WP) correlates with changes in extracellular calcium ([Ca(2+)]o). Here, we test the hypothesis that increasing [Ca(2+)]o reduces WP and increases CV. Mathematical models of EpC also predict that reducing WP can reduce sodium driving force and CV by self-attenuation. Therefore, we further hypothesized that reducing WP and extracellular sodium ([Na(+)]o) will reduce CV consistent with ephaptic self-attenuation. Transmission electron microscopy revealed that increasing [Ca(2+)]o (1 to 3.4 mM) significantly decreased WP Optically mapping wild-type (WT) (100% Cx43) mouse hearts demonstrated that increasing [Ca(2+)]o increases transverse CV during normonatremia (147.3 mM), but slows transverse CV during hyponatremia (120 mM). Additionally, CV in heterozygous (∼50% Cx43) hearts was more sensitive to changes in [Ca(2+)]o relative to WT during normonatremia. During hyponatremia, CV slowed in both WT and heterozygous hearts to the same extent. Importantly, neither [Ca(2+)]o nor [Na(+)]o altered Cx43 expression or phosphorylation determined by Western blotting, or gap junctional resistance determined by electrical impedance spectroscopy. Narrowing WP, by increasing [Ca(2+)]o, increases CV consistent with enhanced EpC between myocytes. Interestingly, during hyponatremia, reducing WP slowed CV, consistent with theoretical predictions of ephaptic self-attenuation. This study suggests that serum ion concentrations may be an important determinant of cardiac disease expression.

  11. Conduction Velocity of the Uterine Contraction in Serial Magnetomyogram (MMG) Data: Event Based Simulation and Validation

    PubMed Central

    Preissl, Hubert; Lowery, Curtis L.; Eswaran, Hari; Govindan, Rathinaswamy B.

    2012-01-01

    We propose a novel approach to calculate the conduction velocity (CV) of the uterine contraction bursts in magnetomyogram (MMG) signals measured using a multichannel SQUID array. For this purpose, we partition the sensor coordinates into four different quadrants and identify the contractile bursts using a previously proposed Hilbert-wavelet transform approach. If contractile burst is identified in more than one quadrant, we calculate the center of gravity (CoG) in each quadrant for each time point as the sum of the product of the sensor coordinates with the Hilbert amplitude of the MMG signals normalized by the sum of the Hilbert amplitude of the signals over all sensors. Following this we compute the delay between the CoGs of all (six) possible quadrant pairs combinations. As a first step, we validate this approach by simulating a stochastic model based on independent second-order autoregressive processes (AR2) and we divide them into 30 second disjoint windows and insert burst activity at specific time instances in preselected sensors. Also we introduce a lag of 5 ± 1 seconds between different quadrants. Using our approach we calculate the CoG of the signals in a quadrant. To this end, we compute the delay between CoGs obtained from different quadrants and show that our approach is able to reliably capture the delay incorporated in the model. We apply the proposed approach to 19 serial MMG data obtained from two subjects and show an increase in the CV as the subjects approached labor. PMID:22255713

  12. Electrophysiological aspects of sensory conduction velocity in healthy adults. 1. Conduction velocity from digit to palm, from palm to wrist, and across the elbow, as a function of age.

    PubMed

    Cruz Martínez, A; Barrio, M; Pérez Conde, M C; Gutiérrez, A M

    1978-12-01

    The sensory conduction velocity from digit to palm and from palm to wrist was determined in median (digit 3) and ulnar (digit 5) nerves in 47 healthy subjects with age range from 21 to 77 years. The decrement of the sensory conduction as a function of age was more marked in the palm to wrist than in the digit to palm segment. Sensory conduction velocity of the ulnar nerve across the elbow was also studied. Irregularities in the shape of the sensory evoked potential recorded above the cubital sulcus were found in 12.76% of cases, especially in subjects over 50 years of age. These results suggest that aging causes decrement in sensory conduction and changes in the shape of the evoked potentials, especially at points where the nerves are more frequently compressed.

  13. Electrophysiological aspects of sensory conduction velocity in healthy adults. 1. Conduction velocity from digit to palm, from palm to wrist, and across the elbow, as a function of age.

    PubMed Central

    Cruz Martínez, A; Barrio, M; Pérez Conde, M C; Gutiérrez, A M

    1978-01-01

    The sensory conduction velocity from digit to palm and from palm to wrist was determined in median (digit 3) and ulnar (digit 5) nerves in 47 healthy subjects with age range from 21 to 77 years. The decrement of the sensory conduction as a function of age was more marked in the palm to wrist than in the digit to palm segment. Sensory conduction velocity of the ulnar nerve across the elbow was also studied. Irregularities in the shape of the sensory evoked potential recorded above the cubital sulcus were found in 12.76% of cases, especially in subjects over 50 years of age. These results suggest that aging causes decrement in sensory conduction and changes in the shape of the evoked potentials, especially at points where the nerves are more frequently compressed. Images PMID:731254

  14. A conduction block in sciatic nerves can be detected by magnetic motor root stimulation.

    PubMed

    Matsumoto, Hideyuki; Konoma, Yuko; Fujii, Kengo; Hanajima, Ritsuko; Terao, Yasuo; Ugawa, Yoshikazu

    2013-08-15

    Useful diagnostic techniques for the acute phase of sciatic nerve palsy, an entrapment neuropathy, are not well established. The aim of this paper is to demonstrate the diagnostic utility of magnetic sacral motor root stimulation for sciatic nerve palsy. We analyzed the peripheral nerves innervating the abductor hallucis muscle using both electrical stimulations at the ankle and knee and magnetic stimulations at the neuro-foramina and conus medullaris levels in a patient with sciatic nerve palsy at the level of the piriformis muscle due to gluteal compression related to alcohol consumption. On the fourth day after onset, magnetic sacral motor root stimulation using a MATS coil (the MATS coil stimulation method) clearly revealed a conduction block between the knee and the sacral neuro-foramina. Two weeks after onset, needle electromyography supported the existence of the focal lesion. The MATS coil stimulation method clearly revealed a conduction block in the sciatic nerve and is therefore a useful diagnostic tool for the abnormal neurophysiological findings associated with sciatic nerve palsy even at the acute phase.

  15. Fractional order sliding-mode control based on parameters auto-tuning for velocity control of permanent magnet synchronous motor.

    PubMed

    Zhang, BiTao; Pi, YouGuo; Luo, Ying

    2012-09-01

    A fractional order sliding mode control (FROSMC) scheme based on parameters auto-tuning for the velocity control of permanent magnet synchronous motor (PMSM) is proposed in this paper. The control law of the proposed F(R)OSMC scheme is designed according to Lyapunov stability theorem. Based on the property of transferring energy with adjustable type in F(R)OSMC, this paper analyzes the chattering phenomenon in classic sliding mode control (SMC) is attenuated with F(R)OSMC system. A fuzzy logic inference scheme (FLIS) is utilized to obtain the gain of switching control. Simulations and experiments demonstrate that the proposed FROSMC not only achieve better control performance with smaller chatting than that with integer order sliding mode control, but also is robust to external load disturbance and parameter variations.

  16. Motor nerve conduction study in cauda equina with high-voltage electrical stimulation in multifocal motor neuropathy and amyotrophic lateral sclerosis.

    PubMed

    Akaza, Miho; Kanouchi, Tadashi; Inaba, Akira; Numasawa, Yoshiyuki; Irioka, Takashi; Mizusawa, Hidehiro; Yokota, Takanori

    2011-02-01

    In this study we aim to establish a motor nerve conduction study (NCS) for the cauda equina and examine its usefulness in multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis (ALS). NCS of the tibial nerve proximal to the knee was performed with an optimized high-voltage electrical stimulation (HV-ES) method in 21 normal subjects, 5 with MMN, and 11 with ALS. HV-ES, but not magnetic stimulation, could supramaximally stimulate the cauda equina. Cauda equina motor conduction time determined by HV-ES, but not that with F-waves, correlated well with cauda equina length on magnetic resonance imaging. HV-ES revealed proximal lesions in 4 MMN patients but in none of the ALS patients. Importantly, 1 patient with "MMN without conduction block (CB)" had a CB in the cauda equina. Cauda equina motor conduction is better evaluated by HV-ES than with F-wave study or magnetic stimulation. HV-ES can help to distinguish MMN and "MMN without CB" from ALS.

  17. The starting transient of solid propellant rocket motors with high internal gas velocities. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Peretz, A.; Caveny, L. H.; Kuo, K. K.; Summerfield, M.

    1973-01-01

    A comprehensive analytical model which considers time and space development of the flow field in solid propellant rocket motors with high volumetric loading density is described. The gas dynamics in the motor chamber is governed by a set of hyperbolic partial differential equations, that are coupled with the ignition and flame spreading events, and with the axial variation of mass addition. The flame spreading rate is calculated by successive heating-to-ignition along the propellant surface. Experimental diagnostic studies have been performed with a rectangular window motor (50 cm grain length, 5 cm burning perimeter and 1 cm hydraulic port diameter), using a controllable head-end gaseous igniter. Tests were conducted with AP composite propellant at port-to-throat area ratios of 2.0, 1.5, 1.2, and 1.06, and head-end pressures from 35 to 70 atm. Calculated pressure transients and flame spreading rates are in very good agreement with those measured in the experimental system.

  18. Conducted EMI Modeling and Mitigation for Power Converters and Motor Drives

    NASA Astrophysics Data System (ADS)

    Sun, J.

    2012-05-01

    The increasing use of power electronics in aircraft power systems to enable new, more-electric aircraft (MEA) functions has also led to increasing EMI emission. EMI filters may account for more than 50% of the overall volume and weight of high-power converters such as variable-speed motor drives. The traditional approach to mitigating EMI requires functional prototypes and EMI measurements before filter design can start. Such an empirical, EMI-last approach results in designs that are suboptimal at best and is a major cause for schedule delay and disruption. This paper reviews recent research on EMI modeling and system solutions to EMI, empha- sizing conducted emission of three-phase converters and variable-speed drives that dominate system EMI filtering requirements. The goal is to enable a concurrent-EMI design approach and to develop optimal system solutions that minimize the overall volume and size.

  19. Assembly of the translocase motor onto the preprotein-conducting channel

    PubMed Central

    Karamanou, Spyridoula; Bariami, Vassiliki; Papanikou, Efrosyni; Kalodimos, Charalampos G.; Economou, Anastassios

    2008-01-01

    Summary Bacterial protein secretion is catalyzed by the SecYEG protein-conducting channel complexed with the SecA ATPase motor. To gain insight into the SecA-SecYEG interaction we used peptide arrays, thermodynamic quantitation, mutagenesis and functional assays. Our data reveal that: a. SecA binds with low affinity on several, peripheral, exposed SecYEG sites. This largely electrostatic association is modulated by temperature and nucleotides. b. Binding sites cluster in five major binding “regions”: three that are exclusively cytoplasmic and two that reach the periplasm. c. Both the aminoterminal and carboxyterminal regions of SecA participate in binding interactions and share some sites. d. Several of these sites are essential for translocase catalysis. Our data provide residue-level dissection of the SecYEG-SecA interaction. Two models of assembly of SecA on dimeric SecYEG are discussed. PMID:18761620

  20. Assembly of the translocase motor onto the preprotein-conducting channel.

    PubMed

    Karamanou, Spyridoula; Bariami, Vassiliki; Papanikou, Efrosyni; Kalodimos, Charalampos G; Economou, Anastassios

    2008-10-01

    Bacterial protein secretion is catalysed by the SecYEG protein-conducting channel complexed with the SecA ATPase motor. To gain insight into the SecA-SecYEG interaction we used peptide arrays, thermodynamic quantification, mutagenesis and functional assays. Our data reveal that: (i) SecA binds with low affinity on several, peripheral, exposed SecYEG sites. This largely electrostatic association is modulated by temperature and nucleotides. (ii) Binding sites cluster in five major binding 'regions': three that are exclusively cytoplasmic and two that reach the periplasm. (iii) Both the N-terminal and c-terminal regions of SecA participate in binding interactions and share some sites. (iv) Several of these sites are essential for translocase catalysis. Our data provide residue-level dissection of the SecYEG-SecA interaction. Two models of assembly of SecA on dimeric SecYEG are discussed.

  1. Evaluation of Specific Heat, Sound Velocity and Lattice Thermal Conductivity of Strained Nanocrystalline Bismuth Antimony Telluride Thin Films

    NASA Astrophysics Data System (ADS)

    Zheng, D.; Tanaka, S.; Miyazaki, K.; Takashiri, M.

    2015-06-01

    To investigate the effect of strain on specific heat, sound velocity and lattice thermal conductivity of nanocrystalline bismuth antimony telluride thin films, we performed both experimental study and modeling. The nanocrystalline thin films had mostly preferred crystal orientation along c-axis, and strains in the both directions of c-axis and a- b-axis. It was found that the thermal conductivity of nanocrystalline thin films decreased greatly as compared with that of bulk alloys. To gain insight into the thermal transport in the strained nanocrystalline thin films, we estimated the lattice thermal conductivity based on the phonon transport model of full distribution of mean free paths accounting for the effects of grain size and strain which was influenced to both the sound velocity and the specific heat. As a result, the lattice thermal conductivity was increased when the strain was shifted from compressive to tensile direction. We also confirmed that the strain was influenced by the lattice thermal conductivity but the reduction of the lattice thermal conductivity of thin films can be mainly attributed to the nano-size effect rather than the strain effect. Finally, it was found that the measured lattice thermal conductivities were in good agreement with modeling.

  2. Power Stroke Angular Velocity Profiles of Archaeal A-ATP Synthase Versus Thermophilic and Mesophilic F-ATP Synthase Molecular Motors.

    PubMed

    Sielaff, Hendrik; Martin, James; Singh, Dhirendra; Biuković, Goran; Grüber, Gerhard; Frasch, Wayne D

    2016-12-02

    The angular velocities of ATPase-dependent power strokes as a function of the rotational position for the A-type molecular motor A3B3DF, from the Methanosarcina mazei Gö1 A-ATP synthase, and the thermophilic motor α3β3γ, from Geobacillus stearothermophilus (formerly known as Bacillus PS3) F-ATP synthase, are resolved at 5 μs resolution for the first time. Unexpectedly, the angular velocity profile of the A-type was closely similar in the angular positions of accelerations and decelerations to the profiles of the evolutionarily distant F-type motors of thermophilic and mesophilic origins, and they differ only in the magnitude of their velocities. M. mazei A3B3DF power strokes occurred in 120° steps at saturating ATP concentrations like the F-type motors. However, because ATP-binding dwells did not interrupt the 120° steps at limiting ATP, ATP binding to A3B3DF must occur during the catalytic dwell. Elevated concentrations of ADP did not increase dwells occurring 40° after the catalytic dwell. In F-type motors, elevated ADP induces dwells 40° after the catalytic dwell and slows the overall velocity. The similarities in these power stroke profiles are consistent with a common rotational mechanism for A-type and F-type rotary motors, in which the angular velocity is limited by the rotary position at which ATP binding occurs and by the drag imposed on the axle as it rotates within the ring of stator subunits.

  3. Velocity measurement inside a motored internal combustion engine using three-component laser Doppler anemometry

    NASA Astrophysics Data System (ADS)

    Chan, V. S. S.; Turner, J. T.

    2000-10-01

    A three-component laser Doppler anemometry (LDA) system has been employed to investigate the structure of the flow inside the cylinder of a motored internal combustion engine. This model engine was reasonably representative of a typical, single cylinder, spark ignition engine although it did not permit firing. It was equipped with overhead valve gear and optical access was provided in the top and side walls of the cylinder. A principal objective was to study the influence of the inlet port design on the flow within the cylinder during the induction and compression strokes of the engine. Here, it can be noted that results obtained in an unfired engine are believed to be representative of the flow behaviour before combustion occurs in a fired engine (see P.O. Witze, Measurements of the spatial distribution and engine speed dependence of turbulent air motion in an i.c. engine, SAE Paper No. 770220, 1977; Witze, Sandia Laboratory Energy Report, SAND 79-8685, Sandia Laboratories, USA, 1979). Experimental data presented for an inclined inlet port configuration reveal the complex three-dimensional nature of the flow inside the model engine cylinder. Not surprisingly, the results also show that the inclined inlet port created flow conditions more favourable to mixing in the cylinder. Specifically, the inclined inlet flow was found to generate a region with a relatively high shear and strong recirculation zones in the cylinder. Inclining the inlet port also produced a more nearly homogeneous flow structure at top dead centre during the compression stroke. The paper identifies the special difficulties encountered in making the LDA measurements. The experimental findings are examined and the problems that arise in presenting time-varying three-dimensional data of this type are discussed. Finally, the future potential of this experimental approach is explored.

  4. Modeling and inversion of elastic wave velocities and electrical conductivity in clastic formations with structural and dispersed shales

    NASA Astrophysics Data System (ADS)

    Aquino-López, A.; Mousatov, A.; Markov, M.; Kazatchenko, E.

    2015-05-01

    This paper presents a new approach for simulating P- and S-wave velocities, and electrical conductivity in shaly-sand rocks and determining the shale spatial distribution (dispersed and/or structural shales). In this approach, we used the effective medium method and hierarchical model for clastic formations. We treat shaly-sand formations as porous natural-composite materials containing: solid grains (such as quartz, feldspars and structural shale) and pores completely filled with a mixture of hydrocarbon, water and dispersed shale. For calculating the effective elastic properties and electrical conductivity of this composite, we have applied the multi-component self-consistent effective media approximation (EMA) method. We simulate the elastic velocities and electrical conductivity for clastic formations in two steps. Firstly, we calculate the effective properties of mixture (combination of water, hydrocarbon and dispersed shale) filling the pores. Then we find the effective elastic and electrical conductivity properties of formation constituted of solid grains (quartz and structural shale) and pores with the effective properties determined in the previous step. We considered that all components are represented by ellipsoids. The aspect ratios (shapes) of grains and pores; are defined as a porosity function obtained for the model of clean sand formations. Modeling results have demonstrated that the shapes of both shale components (dispersed and structural) weakly affect the effective elastic velocities and electrical conductivity of shaly-sand formation and can be approximated by flatted ellipsoids. The model proposed has been used to determine the volumes of dispersed and structural shales for two sets of published experimental data obtained from the cores. For determining the shale distribution, we have performed the joint inversion of the following physical properties: P-, S-wave velocities, total porosity, and total shale volume. Additionally, we have

  5. Central Motor Conduction Studies and Diagnostic Magnetic Resonance Imaging in Children with Severe Primary and Secondary Dystonia

    ERIC Educational Resources Information Center

    McClelland, Verity; Mills, Kerry; Siddiqui, Ata; Selway, Richard; Lin, Jean-Pierre

    2011-01-01

    Aim: Dystonia in childhood has many causes. Imaging may suggest corticospinal tract dysfunction with or without coexistent basal ganglia damage. There are very few published neurophysiological studies on children with dystonia; one previous study has focused on primary dystonia. We investigated central motor conduction in 62 children (34 males, 28…

  6. Flow velocity, water temperature, and conductivity in Shark River Slough, Everglades National Park, Florida: June 2002-July 2003

    USGS Publications Warehouse

    Riscassi, Ami L.; Schaffranek, Raymond W.

    2004-01-01

    The data described in this report were collected in the U. S. Geological Survey (USGS) Priority Ecosystems Science project investigating Forcing Effects on Flow Structure in Vegetated Wetlands of the Everglades. Data collected at five locations in Shark River Slough, Everglades National Park, during the 2002-2003 wet season are documented in the report. Methods used to process the data are described. Daily mean flow velocities, water temperatures, and specific conductance values are presented in the appendices. The quality-checked and edited data have been compiled and stored on the USGS South Florida Information Access (SOFIA) website http://sofia.usgs.gov.

  7. Superresolution imaging reveals activity-dependent plasticity of axon morphology linked to changes in action potential conduction velocity.

    PubMed

    Chéreau, Ronan; Saraceno, G Ezequiel; Angibaud, Julie; Cattaert, Daniel; Nägerl, U Valentin

    2017-02-07

    Axons convey information to nearby and distant cells, and the time it takes for action potentials (APs) to reach their targets governs the timing of information transfer in neural circuits. In the unmyelinated axons of hippocampus, the conduction speed of APs depends crucially on axon diameters, which vary widely. However, it is not known whether axon diameters are dynamic and regulated by activity-dependent mechanisms. Using time-lapse superresolution microscopy in brain slices, we report that axons grow wider after high-frequency AP firing: synaptic boutons undergo a rapid enlargement, which is mostly transient, whereas axon shafts show a more delayed and progressive increase in diameter. Simulations of AP propagation incorporating these morphological dynamics predicted bidirectional effects on AP conduction speed. The predictions were confirmed by electrophysiological experiments, revealing a phase of slowed down AP conduction, which is linked to the transient enlargement of the synaptic boutons, followed by a sustained increase in conduction speed that accompanies the axon shaft widening induced by high-frequency AP firing. Taken together, our study outlines a morphological plasticity mechanism for dynamically fine-tuning AP conduction velocity, which potentially has wide implications for the temporal transfer of information in the brain.

  8. Dynamic weakening of fault gouge affected by thermal conductivity of host specimen: implications for the high-velocity weakening mechanisms

    NASA Astrophysics Data System (ADS)

    Yao, Lu; Ma, Shengli; Shimamoto, Toshihiko; Niemeijer, André

    2015-04-01

    Since many high-velocity weakening mechanisms are thermal in origin, we study the effects of thermal conductivity of host specimen on fault gouge friction behavior at seismic slip rates. By using host specimens made of brass, stainless steel, Ti-Al-V alloy and gabbro with thermal conductivities of 123, 15, 5.8 and 3.25 W/m/K, respectively, the experiments in this study produce completely different temperature conditions within the same gouge under the same slip rates and normal stresses. Fault gouges used in the experiments are a natural illite- and quartz-rich gouge from Longmenshan fault zone and pure periclase (MgO) nanopowder. High-velocity weakening of gouges were more pronounced with decreasing thermal conductivity of the specimens. Particularly, almost no dynamic weakening was observed in the tests performed with brass host specimens, while tests with specimens of gabbro and Ti-Al-V alloy exhibits quite similar dramatic weakening behaviors. Such differences in gouge frictional behavior cannot be explained by original flash heating model, since asperity contacts within the slip zone and experimental conditions are still same, even though host specimens are different. Microstructure observations under scanning and transmission electron microscopes reveal that slip zone materials tend to change from individual ultrafine nanograins to larger sintered grains or aggregates, with decreasing thermal conductivities of host specimens. Calculated temperature together with observed microstructure indicate that bulk temperature rise may be also play an important role in fault weakening, as predicted by a recent theoretical analysis of the role of flash heating within the gouge zone [Proctor et al., 2014]. Current results demonstrate the importance of frictional heating in causing the dynamic weakening of gouge, and the powder lubrication hypothesis is not consistent with our experimental data.

  9. Performance of a combined three-hole conductivity probe for void fraction and velocity measurement in air-water flows

    NASA Astrophysics Data System (ADS)

    Borges, João Eduardo; Pereira, Nuno H. C.; Matos, Jorge; Frizell, Kathleen H.

    2010-01-01

    The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously the magnitude and direction of the velocity vector in complex air-water flows, is described in this paper. The air-water flows envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing the velocity field of other complex air-water flows.

  10. Relevance of nerve conduction velocity in the assessment of balance performance in older adults with diabetes mellitus.

    PubMed

    Wang, Ting-Yun; Chen, Shih-Ching; Peng, Chih-Wei; Kang, Chun-Wei; Chen, Yu-Luen; Chen, Chun-Lung; Chou, Yi-Lin; Lai, Chien-Hung

    2017-03-01

    Purpose This study investigated the relationship between peripheral nerve conduction velocity (NCV) and balance performance in older adults with diabetes. Methods Twenty older adults with diabetes were recruited to evaluate the NCV of their lower limbs and balance performance. The balance assessments comprised the timed up and go (TUG) test, Berg balance scale (BBS), unipedal stance test (UST), multidirectional reach test (MDRT), maximum step length (MSL) test and quiet standing with eyes open and closed. The relationship between NCV and balance performance was evaluated by Pearson's correlation coefficients, and the balance performances of the diabetic patients with and without peripheral neuropathy were compared by using Mann-Whitney U tests. Results The NCV in the lower limbs exhibited a moderate to strong correlation with most of the balance tests including the TUG (r = -0.435 to -0.520, p < 0.05), BBS (r = 0.406-0.554, p < 0.05), UST (r = 0.409-0.647, p < 0.05) and MSL (r = 0.399-0.585, P < 0.05). In addition, patients with diabetic peripheral neuropathy had a poorer TUG (p < 0.05), BBS (p < 0.01), UST (p < 0.05) and MSL performance (p < 0.05) compared with those without peripheral neuropathy (p < 0.05). Conclusion Our findings revealed that a decline in peripheral nerve conduction in the lower limb is not only an indication of nerve dysfunction, but may also be related to the impairment of balance performance in patients with diabetes. Implications for Rehabilitation Nerve conduction velocity in the lower limbs of diabetic older adults showed moderate to strong correlations with most of the results of balance tests, which are commonly used in clinics. Decline in nerve conduction velocity of the lower limbs may be related to the impairment of balance control in patients with diabetes. Diabetic older adults with peripheral neuropathy exhibited greater postural instability than those without peripheral

  11. Scaling factor relating conduction velocity and diameter for myelinated afferent nerve fibres in the cat hind limb.

    PubMed Central

    Boyd, I A; Kalu, K U

    1979-01-01

    1. Compound action potentials were recorded from certain muscle and cutaneous nerves in normal and chronically de-efferentated hind limbs of cats during stimulation of the appropriate dorsal spinal roots, 2. The peaks for groups I, II and III in the compound action potential were correlated with the corresponding peaks in the fibre-diameter histograms of the same de-efferentated nerve after processing it for light microscopy. 3. The scaling factor (ratio of conduction velocity in m/sec to total diameter in micrometer) was not constant for all sizes of fibre nor did it increase progressively with fibre size. Evidence is presented that a logarithmic relation between conduction velocity and fibre diameter is not appropriate. 4. In muscle nerves the scaling factor for fibres fixed by glutaraldehyde perfusion and embedded in Epon was 5.7 for group I afferent fibres and 4.6 for myelinated fibres in both group II and group III. 5. In cutaneous nerves the scaling factor was 5.6 for large fibres (group I or Abeta) and 4.6 for small fibres (group III or Adelta). 6. The scaling factor for group I fibres is the same as was found previously for alpha-efferent fibres, and that for groups II and III is the same as for gamma-efferent fibres (Boyd & Davey, 1968). 7. The possibility that there is a clear discontinuity in scaling factor between fibres in groups I and alpha, and those in other functional groups, is discussed. 8. It is concluded that there must be some structural feature of alpha and group I fibres which differs from that of smaller myelinated fibres. It is likely that a difference in the relative thickness of the myelin sheath is involved and possibly also in the conductances responsible for generating the action potential. Images Plate 1 PMID:458657

  12. Nerve conduction velocity

    MedlinePlus

    ... polyneuropathy Tibial nerve dysfunction Ulnar nerve dysfunction Any peripheral neuropathy can cause abnormal results. Damage to the spinal ... Herniated disk Lambert-Eaton syndrome Mononeuropathy Multiple ... azotemia Primary amyloidosis Radial nerve dysfunction Sciatica ...

  13. Flow Velocity, Water Temperature, and Conductivity in Shark River Slough, Everglades National Park, Florida: August 2001-June 2002

    USGS Publications Warehouse

    Riscassi, Ami L.; Schaffranek, Raymond W.

    2003-01-01

    The data-collection effort described in this report is in support of the U.S. Geological Survey (USGS) Place-Based Studies project investigating 'Forcing Effects on Flow Structure in Vegetated Wetlands of the Everglades.' Data collected at four locations in Shark River Slough, Everglades National Park, during the 2001-2002 wet season are documented in the report and methods used to process the data are described. Daily mean flow velocities, water temperatures, and specific conductance values are presented in the appendices of the report. The quality-checked and edited data have been compiled and stored on the USGS South Florida Information Access (SOFIA) website http://sofia.usgs.gov.

  14. Association of antibodies to ganglioside complexes and conduction blocks in axonal Guillain-Barré syndrome presenting as acute motor conduction block neuropathy.

    PubMed

    Créange, Alain; Shahrizaila, Nortina; Salhi, Hayet; Lefaucheur, Jean-Pascal; Yuki, Nobuhiro

    2014-06-01

    A close relationship between acute motor conduction block neuropathy and antibodies against the complex of GM1 and GalNAc-GD1a has been reported. This study investigates the hypothesis that conduction block at the early phase of axonal Guillain-Barré syndrome (GBS) is also associated with such ganglioside complexes. Sera were obtained from seven French patients with initial evidence of isolated conduction blocks that resolved or progressed to acute motor axonal neuropathy. Serum IgG to asialo-GM1 and gangliosides of LM1, GM1, GM1b, GD1a, GalNAc-GD1a, GD1b, GT1a, GT1b, and GQ1b as well as their complexes were measured. Five of seven patients progressed within the first month of disease to AMAN. One patient had IgG antibodies against the complex of asialo-GM1 and each of the other ganglioside antigens. Another patient carried IgG antibodies against GM1 complex with GM1b, GD1a, and GT1a as well as asialo-GM1 complex with GD1a and GT1a. None had IgG antibodies against GM1/GalNAc-GD1a complex. Six patients had IgG against single antigens GM1, GD1a, GalNAc-GD1a, GD1b, and asialo-GM1. In three patients, a reduced reaction against GM1/GalNAc-GD1a complex was observed. The presence of conduction block in axonal GBS is not always associated with anti-GM1/GalNAc-GD1a complex antibodies.

  15. The effect of local corticosteroid injection on F-wave conduction velocity and sympathetic skin response in carpal tunnel syndrome.

    PubMed

    Deniz, Orhan; Aygül, Recep; Kotan, Dilcan; Ozdemir, Gökhan; Odabaş, Faruk Omer; Kaya, M Dursun; Ulvi, Hızır

    2012-05-01

    The aim of this study was to evaluate the efficacy of steroid injection for the treatment of the carpal tunnel syndrome (CTS), with F-wave parameters and sympathetic skin response (SSR). Seventeen hands of 10 women patients were treated with local steroid injection with 2-month follow-up. All patients underwent single injection into the carpal tunnel. Response to injection was measured nerve conduction studies (NCSs), median nerve F waves, and SSR before and after treatment. To determine the normal values, 42 hands of 21 healthy women were also studied. There was a significant improvement of sensory and motor nerve conduction values when compared to baseline values (P < 0.01). At the end of follow-up period, the median sensory distal latency and the sensory latency differences between the median and the ulnar nerve were improved 35 and 65%, respectively. The maximum, mean F-wave amplitudes and chronodispersion showed a slight improvement with respect to baseline values and controls, but statistical significance was not achieved after treatment. Although no statistically significant improvements were observed in SSR parameters, slightly decreased amplitudes and increased habituation of SSR were noted at the end of the treatment. The present study shows that the local steroid injection results in improvement in NCSs values, but the F-wave parameters were not effectual in short-term outcome of CTS treatment. These findings suggest that the sensory latency differences between the median and the ulnar wrist-to-digit 4 are better parameters in the median nerve recovery after treatment than the median sensory distal latency. Furthermore, the SSR does not seem to be a sensitive method in follow-up of CTS treatment.

  16. Surface Conductive Graphene-Wrapped Micromotors Exhibiting Enhanced Motion.

    PubMed

    Ma, Xing; Katuri, Jaideep; Zeng, Yongfei; Zhao, Yanli; Sanchez, Samuel

    2015-10-01

    Surface-conductive Janus spherical motors are fabricated by wrapping silica particles with reduced graphene oxide capped with a thin Pt layer. These motors exhibit a 100% enhanced velocity as compared to standard SiO2 -Pt motors. Furthermore, the versatility of graphene may open up possibilities for a diverse range of applications from active drug delivery systems to water remediation.

  17. Repeated ischaemic isometric exercise increases muscle fibre conduction velocity in humans: involvement of Na+-K+-ATPase

    PubMed Central

    Rongen, G A; van Dijk, J P; van Ginneken, E E; Stegeman, D F; Smits, P; Zwarts, M J

    2002-01-01

    This study was performed to test two hypotheses: (1) ischaemic preconditioning (development of tolerance to ischaemia) influences muscle fibre conduction velocity (MFCV) during repeated ischaemic isometric exercise and (2) the increase in MFCV to supranormal levels during recovery from ischaemic exercise is caused by activation of Na+−K+-ATPase. For this purpose, MFCV was measured with surface electromyography (sEMG) during repeated ischaemic isometric exercise of the brachioradial muscle (2 min at 30 % of maximal voluntary contraction). The involvement of ischaemic preconditioning was tested by changing the duration of ischaemia and by intra-arterial infusion of adenosine (brachial artery, 50 μg min−1 dl−1). The role of Na+−K+-ATPase was explored using ouabain (0.2 μg min−1 dl−1). During the exercise, MFCV decreased from 4.4 ± 0.2 m s−1 to 3.7 ± 0.2 m s−1 (P < 0.01, n = 13). Similar reductions in MFCV were observed during repeated exercise, irrespective of the reperfusion time (10 min vs. 18 min) or duration of the ischaemia (2 vs. 10 min). However, initial MFCV gradually increased for each subsequent contraction when contractions were repeated at 10 min intervals (4.4 ± 0.2 m s−1vs. 4.9 ± 0.2 m s−1 for the first and fourth contraction respectively; P < 0.01; n = 13). This increase was not observed when contractions were performed at 18 min intervals, nor when additional ischaemia was applied. Intra-arterial adenosine did not affect MFCV. Intra-arterial ouabain did not affect the reduction in MFCV during exercise but completely prevented the increase in MFCV during recovery: from 4.7 ± 0.2 m s−1 to 5.2 ± 0.2 m s−1vs. 4.5 ± 0.1 m s−1 to 4.5 ± 0.1 m s−1 in the absence and presence of ouabain respectively (P < 0.05 for ouabain effect; n = 6). In conclusion, ischaemic preconditioning is not involved in changes in MFCV during repeated ischaemic isometric exercise. The increase in MFCV during recovery from repeated ischaemic

  18. Effect of Enriched (Complex) Environment on Nerve Conduction Velocity: New Data and Review of Implications for the Speed of Information Processing.

    ERIC Educational Resources Information Center

    Reed, T. Edward

    1993-01-01

    Results with 54 mice confirm that increased stimulation or usage, as would be provided by environmental enrichment (EE), increases peripheral nerve conduction velocity. These results suggest a role at the physiological level for EE (or deprivation) in affecting measured intelligence. (SLD)

  19. Evening primrose oil treatment corrects reduced conduction velocity but not depletion of arachidonic acid in nerve from streptozotocin-induced diabetic rats.

    PubMed

    Kuruvilla, R; Peterson, R G; Kincaid, J C; Eichberg, J

    1998-09-01

    The effects of evening primrose oil (EPO) treatment, a source of gamma-linolenic acid, on the proportions of arachidonoyl-containing molecular species (ACMS) in sciatic nerve phosphatidylcholine and phosphatidylethanolamine were determined in conjunction with alterations in nerve conduction velocity. Normal and diabetic rats were either untreated or fed a dietary supplement containing isocalorically equivalent amounts of either EPO or corn oil for the duration of the experiment. After 8 weeks of streptozotocin-induced diabetes, nerve conduction velocity was reduced 16% and this deficit was prevented by either EPO or corn oil treatment. Neither EPO nor corn oil supplementation significantly increased the depressed proportions of ACMS. The level of the linoleoyl-containing molecular species, 16:0/18:2, was elevated in the phospholipids from untreated diabetic rats and was further increased by EPO treatment. These results are consistent with decreased activity of the delta6 desaturase that is required for arachidonic acid synthesis in vivo, but suggests that an accompanying deficit in the subsequent delta5 desaturase-catalyzed reaction may be rate-limiting. These findings indicate that maintenance of normal ACMS levels is not required for prevention of diminished nerve conduction velocity and suggest that other factors influenced by an altered polyunsaturated fatty acid pattern, such as metabolites of linoleic acid or gamma-linolenic acid other than arachidonic acid, the energy state of the nerve or the degree of membrane fluidity may contribute to impaired nerve conduction velocity in diabetic neuropathy.

  20. The relation between gas density and velocity power spectra in galaxy clusters: High-resolution hydrodynamic simulations and the role of conduction

    NASA Astrophysics Data System (ADS)

    Gaspari, M.; Churazov, E.; Nagai, D.; Lau, E. T.; Zhuravleva, I.

    2014-09-01

    Exploring the power spectrum of fluctuations and velocities in the intracluster medium (ICM) can help us to probe the gas physics of galaxy clusters. Using high-resolution 3D plasma simulations, we study the statistics of the velocity field and its intimate relation with the ICM thermodynamic perturbations. The normalization of the ICM spectrum (related to density, entropy, or pressure fluctuations) is linearly tied to the level of large-scale motions, which excite both gravity and sound waves due to stratification. For a low 3D Mach number M ~ 0.25, gravity waves mainly drive entropy perturbations, which are traced by preferentially tangential turbulence. For M> 0.5, sound waves start to significantly contribute and pass the leading role to compressive pressure fluctuations, which are associated with isotropic (or slightly radial) turbulence. Density and temperature fluctuations are then characterized by the dominant process: isobaric (low M), adiabatic (high M), or isothermal (strong conduction). Most clusters reside in the intermediate regime, showing a mixture of gravity and sound waves, hence drifting toward isotropic velocities. Remarkably, regardless of the regime, the variance of density perturbations is comparable to the 1D Mach number, M1D ~ δρ/ρ. This linear relation allows us to easily convert between gas motions and ICM perturbations (δρ/ρ< 1), which can be exploited by the available Chandra, XMM data and by the forthcoming Astro-H mission. At intermediate and small scales (10-100 kpc), the turbulent velocities develop a tight Kolmogorov cascade. The thermodynamic perturbations (which can be generally described by log-normal distributions) act as effective tracers of the velocity field, in broad agreement with the Kolmogorov-Obukhov-Corrsin advection theory. The cluster radial gradients and compressive features induce a flattening in the cascade of the perturbations. Thermal conduction, on the other hand, acts to damp the thermodynamic

  1. Relationship between the velocity of illusory hand movement and strength of MEG signals in human primary motor cortex and left angular gyrus.

    PubMed

    Casini, Laurence; Roll, Jean-Pierre; Romaiguère, Patricia

    2008-03-01

    We studied the relationship between the velocity of movement illusion and the activity level of primary motor area (M1) and of the left angular gyrus (AG) in humans. To induce illusory movement perception, we applied co-vibration at different frequencies on tendons of antagonistic muscle groups. Since it is well established that the velocity of illusory movement is related to the difference in vibration frequency applied to two antagonistic muscles, we compared magnetoencephalography (MEG) signals recorded in two conditions of co-vibration: in the "fast illusion" condition a frequency difference of 80 Hz was applied on the tendons of the right wrist extensor and flexor muscle groups, whereas in the "slow illusion" condition a frequency difference of 40 Hz was applied on the same muscle groups. The dipole strength, reflecting the activity level of structures, was measured over M1 and the left AG in two different time-periods: 0-400 and 400-800 ms in each condition. Our results showed that the activity level of the AG was similar in both conditions whatever the time-period, whereas the activity level of M1 was higher in the "fast illusion" condition compared to the "slow illusion" condition from 400 ms after the vibration onset only. The data suggest that the two structures differently contributed to the perception of illusory movements. Our hypothesis is that M1 would be involved in the coding of cinematic parameters of the illusory movement but not the AG.

  2. Flow velocity, water temperature, and conductivity at selected locations in Shark River Slough, Everglades National Park, Florida; July 1999 - July 2003

    USGS Publications Warehouse

    Schaffranek, Raymond W.; Riscassi, Ami L.

    2005-01-01

    Flow-velocity, water-temperature, and conductivity data were collected at five locations in Shark River Slough, Everglades National Park (ENP), Florida, from 1999 to 2003. The data were collected as part of the U.S. Geological Survey Priority Ecosystems Science Initiative in support of the Comprehensive Everglades Restoration Plan. This report contains digital files and graphical plots of the processed, quality-checked, and edited data. Information pertinent to the locations and monitoring strategy also is presented.

  3. Differentiating Children with Attention-Deficit/Hyperactivity Disorder, Conduct Disorder, Learning Disabilities and Autistic Spectrum Disorders by Means of Their Motor Behavior Characteristics

    ERIC Educational Resources Information Center

    Efstratopoulou, Maria; Janssen, Rianne; Simons, Johan

    2012-01-01

    The study was designed to investigate the discriminant validity of the Motor Behavior Checklist (MBC) for distinguishing four group of children independently classified with Attention-Deficit/Hyperactivity Disorder, (ADHD; N = 22), Conduct Disorder (CD; N = 17), Learning Disabilities (LD; N = 24) and Autistic Spectrum Disorders (ASD; N = 20).…

  4. Neuro-fuzzy estimation of passive robotic joint safe velocity with embedded sensors of conductive silicone rubber

    NASA Astrophysics Data System (ADS)

    Al-Shammari, Eiman Tamah; Petković, Dalibor; Danesh, Amir Seyed; Shamshirband, Shahaboddin; Issa, Mirna; Zentner, Lena

    2016-05-01

    Robotic operations need to be safe for unpredictable contacts. Joints with passive compliance with springs can be used for soft robotic contacts. However the joints cannot measure external collision forces. In this investigation was developed one passive compliant joint which have soft contacts with external objects and measurement capabilities. To ensure it, conductive silicone rubber was used as material for modeling of the compliant segments of the robotic joint. These compliant segments represent embedded sensors. The conductive silicone rubber is electrically conductive by deformations. The main task was to obtain elastic absorbers for the external collision forces. These absorbers can be used for measurement in the same time. In other words, the joint has an internal measurement system. Adaptive neuro fuzzy inference system (ANFIS) was used to estimate the safety level of the robotic joint by head injury criteria (HIC).

  5. TMEM43 mutation p.S358L alters intercalated disc protein expression and reduces conduction velocity in arrhythmogenic right ventricular cardiomyopathy.

    PubMed

    Siragam, Vinayakumar; Cui, Xuezhi; Masse, Stephane; Ackerley, Cameron; Aafaqi, Shabana; Strandberg, Linn; Tropak, Michael; Fridman, Michael D; Nanthakumar, Kumaraswamy; Liu, Jun; Sun, Yu; Su, Bin; Wang, Caroline; Liu, Xiaoru; Yan, Yuqing; Mendlowitz, Ariel; Hamilton, Robert M

    2014-01-01

    Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a myocardial disease characterized by fibro-fatty replacement of myocardium in the right ventricular free wall and frequently results in life-threatening ventricular arrhythmias and sudden cardiac death. A heterozygous missense mutation in the transmembrane protein 43 (TMEM43) gene, p.S358L, has been genetically identified to cause autosomal dominant ARVC type 5 in a founder population from the island of Newfoundland, Canada. Little is known about the function of the TMEM43 protein or how it leads to the pathogenesis of ARVC. We sought to determine the distribution of TMEM43 and the effect of the p.S358L mutation on the expression and distribution of various intercalated (IC) disc proteins as well as functional effects on IC disc gap junction dye transfer and conduction velocity in cell culture. Through Western blot analysis, transmission electron microscopy (TEM), immunofluorescence (IF), and electrophysiological analysis, our results showed that the stable expression of p.S358L mutation in the HL-1 cardiac cell line resulted in decreased Zonula Occludens (ZO-1) expression and the loss of ZO-1 localization to cell-cell junctions. Junctional Plakoglobin (JUP) and α-catenin proteins were redistributed to the cytoplasm with decreased localization to cell-cell junctions. Connexin-43 (Cx43) phosphorylation was altered, and there was reduced gap junction dye transfer and conduction velocity in mutant TMEM43-transfected cells. These observations suggest that expression of the p.S358L mutant of TMEM43 found in ARVC type 5 may affect localization of proteins involved in conduction, alter gap junction function and reduce conduction velocity in cardiac tissue.

  6. Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media

    NASA Astrophysics Data System (ADS)

    Strutz, Tessa J.; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

    2016-08-01

    Successful groundwater remediation by injecting nanoscale zero-valent iron (NZVI) particles requires efficient particle transportation and distribution in the subsurface. This study focused on the influence of injection velocity and particle concentration on the spatial NZVI particle distribution, the deposition processes and on quantifying the induced decrease in hydraulic conductivity (K) as a result of particle retention by lab tests and numerical simulations. Horizontal column tests of 2 m length were performed with initial Darcy injection velocities (q0) of 0.5, 1.5, and 4.1 m/h and elemental iron input concentrations (Fe0in) of 0.6, 10, and 17 g/L. Concentrations of Fe0 in the sand were determined by magnetic susceptibility scans, which provide detailed Fe0 distribution profiles along the column. NZVI particles were transported farther at higher injection velocity and higher input concentrations. K decreased by one order of magnitude during injection in all experiments, with a stronger decrease after reaching Fe0 concentrations of about 14-18 g/kg(sand). To simulate the observed nanoparticle transport behavior the existing finite-element code OGS has been successfully extended and parameterized for the investigated experiments using blocking, ripening, and straining as governing deposition processes. Considering parameter relationships deduced from single simulations for each experiment (e.g. deposition rate constants as a function of flow velocity) one mean parameter set has been generated reproducing the observations in an adequate way for most cases of the investigated realistic injection conditions. An assessment of the deposition processes related to clogging effects showed that the percentage of retention due to straining and ripening increased during experimental run time resulting in an ongoing reduction of K. Clogging is mainly evoked by straining which dominates particle deposition at higher flow velocities, while blocking and ripening play a

  7. Differentiating children with attention-deficit/hyperactivity disorder, conduct disorder, learning disabilities and autistic spectrum disorders by means of their motor behavior characteristics.

    PubMed

    Efstratopoulou, Maria; Janssen, Rianne; Simons, Johan

    2012-01-01

    The study was designed to investigate the discriminant validity of the Motor Behavior Checklist (MBC) for distinguishing four group of children independently classified with Attention-Deficit/Hyperactivity Disorder, (ADHD; N=22), Conduct Disorder (CD; N=17), Learning Disabilities (LD; N=24) and Autistic Spectrum Disorders (ASD; N=20). Physical education teachers used the MBC for children to rate their pupils based on their motor related behaviors. A multivariate analysis revealed significant differences among the groups on different problem scales. The results indicated that the MBC for children may be effective in discriminating children with similar disruptive behaviors (e.g., ADHD, CD) and autistic disorders, based on their motor behavior characteristics, but not children with Learning Disabilities (LD), when used by physical education teachers in school settings.

  8. Determination of electrode to nerve fiber distance and nerve conduction velocity through spectral analysis of the extracellular action potentials recorded from earthworm giant fibers.

    PubMed

    Qiao, Shaoyu; Odoemene, Onyekachi; Yoshida, Ken

    2012-08-01

    Microneurography and the use of selective microelectrodes that can resolve single-unit nerve activity have become a tool to understand the coding within the nervous system and a clinical diagnostic tool to assess peripheral neural pathologies. Central to these techniques is the use of the differences in the shape of the extracellular action potential (AP) waveform to identify and discriminate units from one another. Theoretical modeling of the origins of these shape differences has shown that the position of the nerve fiber relative to the electrode and the conduction velocity of the unit contribute to these differences giving rise to the hypothesis that more information about the fiber and its relationship to the electrode could be extracted given further analysis of the AP waveform. This paper addresses this question by exploring the electrical coupling between the electrode and nerve fiber. Idealized models and the literature indicate that two parameters, the electrode-fiber distance and the unit conduction velocity, contribute to the amplitude of the extracellular AP detected by the electrode, which confounds the quantification of coupling using the spike amplitude alone. To resolve this, we develop a method that enables differential quantification of these two parameters using spectral analysis of the single-unit AP waveform and demonstrate that the two parameters could be effectively decoupled in an in vitro earthworm model. The method could open the way forward toward micro-scale in situ monitoring of the interaction of nerve fiber and neural interface.

  9. The Expanded Bead Size of Corneal C-Nerve Fibers Visualized by Corneal Confocal Microscopy Is Associated with Slow Conduction Velocity of the Peripheral Nerves in Patients with Type 2 Diabetes Mellitus

    PubMed Central

    2016-01-01

    This study aims to establish the corneal nerve fiber (CNF) morphological alterations in a large cohort of type 2 diabetic patients and to investigate the association between the bead size, a novel parameter representing composite of accumulated mitochondria, glycogen particles, and vesicles in CNF, and the neurophysiological dysfunctions of the peripheral nerves. 162 type 2 diabetic patients and 45 healthy control subjects were studied in detail with a battery of clinical and neurological examinations and corneal confocal microscopy. Compared with controls, patients had abnormal CNF parameters. In particular the patients had reduced density and length of CNF and beading frequency and increased bead size. Alterations in CNF parameters were significant even in patients without neuropathy. The HbA1c levels were tightly associated with the bead size, which was inversely related to the motor and sensory nerve conduction velocity (NCV) and to the distal latency period of the median nerve positively. The CNF density and length positively correlated with the NCV and amplitude. The hyperglycemia-induced expansion of beads in CNF might be a predictor of slow NCV in peripheral nerves in type 2 diabetic patients. PMID:27563679

  10. A Study of Cortical Excitability, Central Motor Conduction, and Cortical Inhibition Using Single Pulse Transcranial Magnetic Stimulation in Patients with Early Frontotemporal and Alzheimer's Dementia

    PubMed Central

    Chandra, Sadanandavalli Retnaswami; Issac, Thomas Gregor; Nagaraju, B. C.; Philip, Mariamma

    2016-01-01

    Introduction: Degenerative cortical dementias affect several million people worldwide. Early diagnosis and categorization are essential for initiating appropriate pharmacological and nonpharmacological treatment so that deterioration can be postponed, and disability adjusted life years can be saved both for the patient and for the caregiver. Therefore, an early, simple, noninvasive biomarker will serve as a boon. Patients and Methods: Patients who satisfied probable Alzheimer's disease (AD) or frontotemporal dementia (FTD) using international consensus criteria for FTD and National Institute of Neurological Disorders and Stroke-AD and Related Disorders Association criteria for AD were evaluated using single pulse transcranial magnetic stimulation with figure of eight coil and motor evoked potential from right first dorsal interossei. Resting threshold (MT), central motor conduction time (CMCT), and silent period (SP) were evaluated. Results: Resting MT and SP are reduced in patients with Alzheimer's disease whereas CMCT is prolonged in patients with FTD and SP is in the lower limit of normal in both conditions. Conclusion: The patterns of central motor conduction and MT are distinctly different in patients with early Alzheimer's disease (AD) and FTD. PMID:27011398

  11. The tissue velocity imaging and strain rate imaging in the assessment of interatrial electromechanical conduction in patients with sick sinus syndrome before and after pacemaker implantation.

    PubMed

    Zheng, Xiaozhi; Ji, Ping; Mao, Hongwei; Hu, Jianqun

    2011-05-01

    Tissue velocity imaging (TVI) and strain rate imaging (SRI) were recently introduced to quantify myocardial mechanical activity in patients receiving cardiac resynchronization therapy. To clear whether atrial-demand-based (AAI) (R) atrial pacing can fully simulate the electromechanical conduction of physiological state and to clarify which one is more appropriate for the assessment of electromechanical activity of the heart between TVI and SRI, 30 normal subjects and 31 patients with sick sinus syndrome (SSS) before and after AAI(R) pacemaker implantation (PI) were investigated in this study. The results showed that the time intervals (ms), P-SRa assessed by SRI (not P-Va assessed by TVI) prolonged step by step from the lateral wall of the right atrium (RA), the interatrial septum (IAS) and the left atrium (LA) in normal subjects(5.01±0.62, 17.05±3.54 and 45.09±12.26, p<0.01). P-Va and P-SRa did not differ at the RA, IAS and LA in patients with SSS before PI (p>0.05), and they were significant longer than those of normal subjects (p<0.01). However, they shortened to normal levels in patients with SSS after PI and P-SRa showed again the trend of gradually prolonging from the RA, IAS to LA. At the same time, the peak velocities and the peak strain rates during atrial contraction also returned to normal values from lower levels. These data suggested that AAI(R) atrial pacing can successfully reverse the abnormal interatrial electromechanical conduction in patients with SSS, and SRI is more appropriate for the assessment of the electromechanical activity of atrial wall than TVI.

  12. Comparison of the duration and power spectral changes of monopolar and bipolar M waves caused by alterations in muscle fibre conduction velocity.

    PubMed

    Rodriguez-Falces, Javier; Navallas, Javier; Malanda, Armando; Rodriguez-Martin, Olivia

    2014-08-01

    The muscle compound action potential (M wave) recorded under monopolar configuration reflects both the propagation of the action potentials along the muscle fibres and their extinction at the tendon. M waves recorded under a bipolar configuration contain less cross talk and noise than monopolar M waves, but they do not contain the entire informative content of the propagating potential. The objective of this study was to compare the effect of changes in muscle fibre conduction velocity (MFCV) on monopolar and bipolar M waves and how this effect depends on the distance between the recording electrodes and tendon. The study was based on a simulation approach and on an experimental investigation of the characteristics of surface M waves evoked in the vastus lateralis during 4-s step-wise isometric contractions in knee extension at 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% MVC. The peak-to-peak duration (Durpp) and median frequency (Fmedian) of the M waves were calculated. For monopolar M waves, changes in Durpp and Fmedian produced by MFCV depended on the distance from the electrode to the tendon, whereas, for bipolar M waves, changes in Durpp and Fmedian were largely independent of the electrode-to-tendon distance. When the distance between the detection point and tendon lay between approximately 15 and 40mm, changes in Durpp of bipolar M waves were more pronounced than those of distal monopolar M waves but less marked than those of proximal monopolar M waves, and the opposite occurred for Fmedian. Since, for bipolar M waves, changes in duration and power spectral features produced by alterations in MFCV are not influenced by the electrode-to-tendon distance, the bipolar electrode configuration is a preferable choice over monopolar arrangements to estimate changes in conduction velocity.

  13. Preliminary results of thermal conductivity and elastic wave velocity measurements of various rock samples collected from outcrops in hanging wall of the Alpine Fault

    NASA Astrophysics Data System (ADS)

    Lin, W.; Tadai, O.; Shigematsu, N.; Nishikawa, O.; Mori, H.; Townend, J.; Capova, L.; Saito, S.; Kinoshita, M.

    2015-12-01

    The Alpine Fault is a mature active fault zone likely to rupture in the near future and DFDP aims to measure physical and chemical conditions within the fault. DFDP-2B borehole was drilled into hanging wall of the Alpine Fault. Downhole temperature measurements carried out in DFDP-2B borehole showed that the geothermal gradient in the hanging wall of the fault is very high, likely reaching to 130-150 °C/km (Sutherland et al., 2015 AGU Fall Meeting). To explain this abnormal feature, the determination of thermal properties of all the rock types in the hanging wall of the Alpine Fault is essential. To measure thermal properties and elastic wave velocities, we collected six typical rock block samples from outcrops in Stony creek and Gaunt creek. These include ultramylonite, mylonite, muscovite schist, garnet amphibolite, protomylonite and schist, which are representative of the hanging wall of the Alpine Fault. Their wet bulk densities are 2.7 - 2.8 g/cm3, and porosities are 1.4 - 3.0%. We prepared a pair of 4 cm cube specimens of each rock type with one flat plane parallel to the foliation. First, we measured thermal conductivity by the transient plane heat source (hot disc) method in a bulk mode, i.e. to deal with the rock as an isotropic material. However, several samples have clearly visible foliation and are likely to be anisotropic. Thus, the data measured in bulk mode provided an average value of the rocks in the range of approximately 2.4 - 3.2 W/mK. The next step will be to measure thermal conductivity in an anisotropic mode. We also measured P wave velocity (Vp) using the same samples, but in two directions, i.e. parallel and perpendicular to the foliation, respectively. Our preliminary results suggested that Vp is anisotropic in all the six rocks. Generally, Vp parallel to foliation is higher than that in the perpendicular direction. Vp in the parallel direction ranged in 5.5 - 6.0 km/s, whereas in the perpendicular direction it was 4.4 - 5.5 km/s. We

  14. AB310. SPR-37 Cholinergic excitatory motor responses in the colon are mediated through the calcium-activated chloride conductance Ano1

    PubMed Central

    Hwang, Sung Jin; Blair, Peter J.; Rock, Jason; Pardo, David; Sanders, Kenton M.; Ward, Sean M.

    2016-01-01

    Objective There is a growing body of evidence that gastrointestinal smooth muscle excitability is regulated by several different classes of interstitial cells [interstitial cells of Cajal (ICC) and PDGFRα(+) cells] that are electrically coupled to SMC. Thus, ‘myogenic’ activity results from the integrated behavior of the SMC/ICC/PDGFRα(+) cell (SIP) syncytium. Inputs from excitatory and inhibitory motor neurons are required to produce the complex motor patterns of the gut and coordinate GI motility. Motor neurons innervate these three cell types in the SIP syncytium, and receptors, second messenger pathways, and ion channels in these cells mediate postjunctional responses. Cholinergic neurotransmission in GI muscles from several species has long been thought to be dependent upon activation of a non-selective cation conductance in smooth muscle cells and the molecular candidates for mediating cholinergic excitation have been reported to be the transient receptor protein channels Trpc4 and Trpc6. However, we have shown that cholinergic responses in the GI tract involve ICC and in their absence these motor responses are greatly diminished or absent. We sought to determine the conductance(s) responsible for cholinergic motor responses in the colon. Methods Cre-LoxP recombinase technology was utilized to determine the role of the calcium-activated chloride conductance, Ano1 in post-junctional motor responses in the mouse colon in a cell-specific manner (Kit+ ICC). c-KitCreERT2/+ (Kit-Cre) mice and Ano f/f mice were crossed to generate c-KitCreERT2/+; Ano1f/f (mutants) and c-KitCreERT2/+; Ano1f/+ (controls) animals that were subsequently treated with tamoxifen to induce Cre recombinase expression in ICC. Confocal microscopy was used to determine the cell type Cre expression was switched on. Intracellular microelectrode recordings were performed to determine changes in post-junctional neural responses to nerve stimulation in c-KitCreERT2/+ (Kit-Cre) mice and Anof

  15. Regulation of Conduction Time along Axons

    PubMed Central

    Seidl, Armin H.

    2013-01-01

    Timely delivery of information is essential for proper function of the nervous system. Precise regulation of nerve conduction velocity is needed for correct exertion of motor skills, sensory integration and cognitive functions. In vertebrates, the rapid transmission of signals along nerve fibers is made possible by the myelination of axons and the resulting saltatory conduction in between nodes of Ranvier. Myelin is a specialization of glia cells and is provided by oligodendrocytes in the central nervous system. Myelination not only maximizes conduction velocity, but also provides a means to systematically regulate conduction times in the nervous system. Systematic regulation of conduction velocity along axons, and thus systematic regulation of conduction time in between neural areas, is a common occurrence in the nervous system. To date, little is understood about the mechanism that underlies systematic conduction velocity regulation and conduction time synchrony. Node assembly, internode distance (node spacing) and axon diameter - all parameters determining the speed of signal propagation along axons - are controlled by myelinating glia. Therefore, an interaction between glial cells and neurons has been suggested. This review summarizes examples of neural systems in which conduction velocity is regulated by anatomical variations along axons. While functional implications in these systems are not always clear, recent studies in the auditory system of birds and mammals present examples of conduction velocity regulation in systems with high temporal precision and a defined biological function. Together these findings suggest an active process that shapes the interaction between axons and myelinating glia to control conduction velocity along axons. Future studies involving these systems may provide further insight into how specific conduction times in the brain are established and maintained in development. Throughout the text, conduction velocity is used for the

  16. Regulation of conduction time along axons.

    PubMed

    Seidl, A H

    2014-09-12

    Timely delivery of information is essential for proper functioning of the nervous system. Precise regulation of nerve conduction velocity is needed for correct exertion of motor skills, sensory integration and cognitive functions. In vertebrates, the rapid transmission of signals along nerve fibers is made possible by the myelination of axons and the resulting saltatory conduction in between nodes of Ranvier. Myelin is a specialization of glia cells and is provided by oligodendrocytes in the central nervous system. Myelination not only maximizes conduction velocity, but also provides a means to systematically regulate conduction times in the nervous system. Systematic regulation of conduction velocity along axons, and thus systematic regulation of conduction time in between neural areas, is a common occurrence in the nervous system. To date, little is understood about the mechanism that underlies systematic conduction velocity regulation and conduction time synchrony. Node assembly, internode distance (node spacing) and axon diameter - all parameters determining the speed of signal propagation along axons - are controlled by myelinating glia. Therefore, an interaction between glial cells and neurons has been suggested. This review summarizes examples of neural systems in which conduction velocity is regulated by anatomical variations along axons. While functional implications in these systems are not always clear, recent studies on the auditory system of birds and mammals present examples of conduction velocity regulation in systems with high temporal precision and a defined biological function. Together these findings suggest an active process that shapes the interaction between axons and myelinating glia to control conduction velocity along axons. Future studies involving these systems may provide further insight into how specific conduction times in the brain are established and maintained in development. Throughout the text, conduction velocity is used for the

  17. Conduction Aphasia, Sensory-Motor Integration, and Phonological Short-term Memory – an Aggregate analysis of Lesion and fMRI data

    PubMed Central

    Buchsbaum, Bradley R.; Baldo, Juliana; Okada, Kayoko; Berman, Karen F.; Dronkers, Nina; D’Esposito, Mark; Hickok, Gregory

    2011-01-01

    Conduction aphasia is a language disorder characterized by frequent speech errors, impaired verbatim repetition, a deficit in phonological short-term memory, and naming difficulties in the presence of otherwise fluent and grammatical speech output. While traditional models of conduction aphasia have typically implicated white matter pathways, recent advances in lesions reconstruction methodology applied to groups of patients have implicated left temporoparietal zones. Parallel work using functional magnetic resonance imaging (fMRI) has pinpointed a region in the posterior most portion of the left planum temporale, area Spt, which is critical for phonological working memory. Here we show that the region of maximal lesion overlap in a sample of 14 patients with conduction aphasia perfectly circumscribes area Spt, as defined in an aggregate fMRI analysis of 105 subjects performing a phonological working memory task. We provide a review of the evidence supporting the idea that Spt is an interface site for the integration of sensory and vocal tract-related motor representations of complex sound sequences, such as speech and music and show how the symptoms of conduction aphasia can be explained by damage to this system. PMID:21256582

  18. Reduction of Common-Mode Conducted Noise Emissions in PWM Inverter-fed AC Motor Drive Systems using Optimized Passive EMI Filter

    NASA Astrophysics Data System (ADS)

    Jettanasen, C.; Ngaopitakkul, A.

    2010-10-01

    Conducted electromagnetic interference (EMI) generated by PWM inverter-fed induction motor drive systems, which are currently widely used in many industrial and/or avionic applications, causes severe parasitic current problems, especially at high frequencies (HF). These restrict power electronic drive's evolution. In order to reduce or minimize these EMI problems, several techniques can be applied. In this paper, insertion of an optimized passive EMI filter is proposed. This filter is optimized by taking into account real impedances of each part of a considered AC motor drive system contrarily to commercial EMI filters designed by considering internal impedance of disturbance source and load, equal to 50Ω. Employing the latter EMI filter would make EMI minimization less effective. The proposed EMI filter optimization is mainly dedicated to minimize common mode (CM) currents due to its most dominant effects in this kind of system. The efficiency of the proposed optimization method using two-port network approach is deduced by comparing the minimized CM current spectra to an applied normative level (ex. DO-160D in aeronautics).

  19. Spontaneous temporal changes and variability of peripheral nerve conduction analyzed using a random effects model.

    PubMed

    Krøigård, Thomas; Gaist, David; Otto, Marit; Højlund, Dorthe; Selmar, Peter E; Sindrup, Søren H

    2014-08-01

    The reproducibility of variables commonly included in studies of peripheral nerve conduction in healthy individuals has not previously been analyzed using a random effects regression model. We examined the temporal changes and variability of standard nerve conduction measures in the leg. Peroneal nerve distal motor latency, motor conduction velocity, and compound motor action potential amplitude; sural nerve sensory action potential amplitude and sensory conduction velocity; and tibial nerve minimal F-wave latency were examined in 51 healthy subjects, aged 40 to 67 years. They were reexamined after 2 and 26 weeks. There was no change in the variables except for a minor decrease in sural nerve sensory action potential amplitude and a minor increase in tibial nerve minimal F-wave latency. Reproducibility was best for peroneal nerve distal motor latency and motor conduction velocity, sural nerve sensory conduction velocity, and tibial nerve minimal F-wave latency. Between-subject variability was greater than within-subject variability. Sample sizes ranging from 21 to 128 would be required to show changes twice the magnitude of the spontaneous changes observed in this study. Nerve conduction studies have a high reproducibility, and variables are mainly unaltered during 6 months. This study provides a solid basis for the planning of future clinical trials assessing changes in nerve conduction.

  20. Position-and Velocity- Sensorless Control of Cylindrical Brushless DC Motors Driven by Sinusoidal Current at Low Speed Using Eddy Current

    NASA Astrophysics Data System (ADS)

    Takashima, Hiroshi; Tomita, Mutuwo; Chen, Zhiqian; Satoh, Mitsuhiko; Doki, Shinji; Okuma, Shigeru

    This paper proposes to paste non-magnetic materials on the rotor surface of a cylindrical brushless DC motor and to use the model including the extended e.m.f. for sensorless control. In the proposed method, the inductance changes depending on the rotor position because of eddy currents, which flow on the non-magnetic material at high frequency. The rotor position can be estimated at standstill and at low speeds. The simulation results show that the proposed method is very useful.

  1. Motor unit activity after eccentric exercise and muscle damage in humans.

    PubMed

    Semmler, J G

    2014-04-01

    It is well known that unaccustomed eccentric exercise leads to muscle damage and soreness, which can produce long-lasting effects on muscle function. How this muscle damage influences muscle activation is poorly understood. The purpose of this brief review is to highlight the effect of eccentric exercise on the activation of muscle by the nervous system, by examining the change in motor unit activity obtained from surface electromyography (EMG) and intramuscular recordings. Previous research shows that eccentric exercise produces unusual changes in the EMG–force relation that influences motor performance during isometric, shortening and lengthening muscle contractions and during fatiguing tasks. When examining the effect of eccentric exercise at the single motor unit level, there are substantial changes in recruitment thresholds, discharge rates, motor unit conduction velocities and synchronization, which can last for up to 1 week after eccentric exercise. Examining the time course of these changes suggests that the increased submaximal EMG after eccentric exercise most likely occurs through a decrease in motor unit conduction velocity and an increase in motor unit activity related to antagonist muscle coactivation and low-frequency fatigue. Furthermore, there is a commonly held view that eccentric exercise produces preferential damage to high-threshold motor units, but the evidence for this in humans is limited. Further research is needed to establish whether there is preferential damage to high-threshold motor units after eccentric exercise in humans, preferably by linking changes in motor unit activity with estimates of motor unit size using selective intramuscular recording techniques.

  2. Behavioral and electromyographic assessment of oxaliplatin-induced motor dysfunctions: Evidence for a therapeutic effect of allopregnanolone.

    PubMed

    Taleb, O; Bouzobra, F; Tekin-Pala, H; Meyer, L; Mensah-Nyagan, A G; Patte-Mensah, C

    2017-03-01

    The antineoplastic oxaliplatin (OXAL) is pivotal for metastatic cancer treatments. However, OXAL evokes sensory and motor side-effects including pain, muscle weakness, motor nerve fiber dysfunctions/neuropathies that significantly impact patients' lives. Therefore, preclinical investigations are struggling to characterize effective analgesics against OXAL-induced painful/sensory symptoms but surprisingly, OXAL-evoked motor dysfunctions received little attention although these neurological symptoms are also disabling for patients. Here, we validated a rat model of OXAL-induced motor neuropathy by using (i) behavioral methods as the wire suspension and balance beam tests to assess muscle weakness and (ii) electrophysiological techniques to record the gastrocnemius electromyography (EMG). The conductance velocity of motor fibers was reduced and compound muscle action potential (CMAP) duration increased in OXAL-treated rats, leading to CMAP dispersion with no modification of the area under the curve, reflecting a heterogeneous demyelination of motor fibers. Functional motor unit analysis revealed a 50 % decrease of their estimated number which was compensated by a motor unit size increase. OXAL-induced motor weakness appeared as a combined consequence of motor fiber demyelination and motor axonopathy. Because we previously observed that allopregnanolone (AP) counteracted OXAL-evoked painful/sensory symptoms, we evaluated its action against OXAL-induced motor neurological dysfunctions. AP treatment successfully corrected motor behaviors, conductance velocity, CMAP duration, motor unit number (MUN) and motor unit size altered by OXAL-chemotherapy. These results, which are the first to show that AP efficiently rescues OXAL-induced motor neuropathy, consolidate the idea that AP-based therapy may be relevant for the treatment of both sensory and motor peripheral neuropathies.

  3. Experiments with a DC Motor

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2010-01-01

    Experiments with an electric motor provide good opportunity to demonstrate some basic laws of electricity and magnetism. The aim of the experiments with a low-power dc motor is to show how the motor approaches its steady rotation and how its torque, mechanical power and efficiency depend on the rotation velocity. The tight relationship between the…

  4. Enhanced robust fractional order proportional-plus-integral controller based on neural network for velocity control of permanent magnet synchronous motor.

    PubMed

    Zhang, Bitao; Pi, YouGuo

    2013-07-01

    The traditional integer order proportional-integral-differential (IO-PID) controller is sensitive to the parameter variation or/and external load disturbance of permanent magnet synchronous motor (PMSM). And the fractional order proportional-integral-differential (FO-PID) control scheme based on robustness tuning method is proposed to enhance the robustness. But the robustness focuses on the open-loop gain variation of controlled plant. In this paper, an enhanced robust fractional order proportional-plus-integral (ERFOPI) controller based on neural network is proposed. The control law of the ERFOPI controller is acted on a fractional order implement function (FOIF) of tracking error but not tracking error directly, which, according to theory analysis, can enhance the robust performance of system. Tuning rules and approaches, based on phase margin, crossover frequency specification and robustness rejecting gain variation, are introduced to obtain the parameters of ERFOPI controller. And the neural network algorithm is used to adjust the parameter of FOIF. Simulation and experimental results show that the method proposed in this paper not only achieve favorable tracking performance, but also is robust with regard to external load disturbance and parameter variation.

  5. Summary of a study to determine low-velocity impact damage and residual tension strength for a thick graphite/epoxy motor case

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.

    1990-01-01

    Impacters of various shapes and masses were dropped from various heights onto 36 mm (1.4 in.) thick graphite/epoxy cylinders, which represented filament wound cases (FWC) for the booster motors of the Space Shuttle. Insert solid propellant was cast into some of the cylinders. The cylinders were impacted numerous times around the circumference and then cut into 51 mm (2.0 in.) wide tension specimens, each containing an impact site. Four indenters were used: a sharp corner, two hemispheres, and a bolt-like rod. The diameters of the hemispheres were 12.7 mm mm (0.5 in.) and 25.4 mm (1.0 in.), and the diameter of the rod was 6.3 mm (0.25 in.). Impacts with the rod were simulated by pressing the rod against the face of specimens. For the hemispheres, the damage initiated beneath the surface at a critical contact pressure and was not visible on the surface until an even larger pressure was exceeded. The damage consisted of matrix cracking and broken fiber. The rod an corner made visible surface damage in all tests. For the hemispheres, the tension strength was reduced considerably before the damage was visible on the surface, 30 percent for the 25.4 mm (1.0 in.) diameter hemisphere and 10 percent for the 12.7 mm (0.5 in.) diameter hemisphere. Analytical methods were used to predict the damage and residual tension strength. A factor of safety to account for nonvisible damage was determined.

  6. Specific changes in conduction velocity recovery cycles of single nociceptors in a patient with erythromelalgia with the I848T gain-of-function mutation of Nav1.7.

    PubMed

    Namer, Barbara; Ørstavik, Kristin; Schmidt, Roland; Kleggetveit, Inge-Petter; Weidner, Christian; Mørk, Cato; Kvernebo, Mari Skylstad; Kvernebo, Knut; Salter, Hugh; Carr, Thomas Hedley; Segerdahl, Märta; Quiding, Hans; Waxman, Stephen George; Handwerker, Hermann Otto; Torebjörk, Hans Erik; Jørum, Ellen; Schmelz, Martin

    2015-09-01

    Seven patients diagnosed with erythromelalgia (EM) were investigated by microneurography to record from unmyelinated nerve fibers in the peroneal nerve. Two patients had characterized variants of sodium channel Nav1.7 (I848T, I228M), whereas no mutations of coding regions of Navs were found in 5 patients with EM. Irrespective of Nav1.7 mutations, more than 50% of the silent nociceptors in the patients with EM showed spontaneous activity. In the patient with mutation I848T, all nociceptors, but not sympathetic efferents, displayed enhanced early subnormal conduction in the velocity recovery cycles and the expected late subnormality was reversed to supranormal conduction. The larger hyperpolarizing shift of activation might explain the difference to the I228M mutation. Sympathetic fibers that lack Nav1.8 did not show supranormal conduction in the patient carrying the I848T mutation, confirming in human subjects that the presence of Nav1.8 crucially modulates conduction in cells expressing EM mutant channels. The characteristic pattern of changes in conduction velocity observed in the patient with the I848T gain-of function mutation in Nav1.7 could be explained by axonal depolarization and concomitant inactivation of Nav1.7. If this were true, activity-dependent hyperpolarization would reverse inactivation of Nav1.7 and account for the supranormal CV. This mechanism might explain normal pain thresholds under resting conditions.

  7. Flow-Velocity, Water-Temperature and Conductivity Data Collected in Shark River Slough, Everglades National Park, During 1999-2000 and 2000-2001 Wet Seasons

    USGS Publications Warehouse

    Riscassi, Ami L.; Schaffranek, R.W.

    2002-01-01

    A project within the U. S. Geological Survey Place- Based Studies Program is focused on investigation of ?Forcing Effects on Flow Structure in Vegetated Wetlands of the Everglades.? Data-collection efforts conducted within this project at three locations in Shark River Slough, Everglades National Park, during the 1999-2000 and 2000-2001 wet seasons are described in this report. Techniques for collecting and processing the data and summaries of daily mean flowvelocity, water-temperature, and conductivity data are presented. The quality-checked and edited data have been compiled and stored on the USGS South Florida Information Access website.

  8. Wind motor applications for transportation

    SciTech Connect

    Lysenko, G.P.; Grigoriev, B.V.; Karpin, K.B.

    1996-12-31

    Motion equation for a vehicle equipped with a wind motor allows, taking into account the drag coefficients, to determine the optimal wind drag velocity in the wind motor`s plane, and hence, obtain all the necessary data for the wind wheel blades geometrical parameters definition. This optimal drag velocity significantly differs from the flow drag velocity which determines the maximum wind motor power. Solution of the motion equation with low drag coefficients indicates that the vehicle speed against the wind may be twice as the wind speed. One of possible transportation wind motor applications is its use on various ships. A ship with such a wind motor may be substantially easier to steer, and if certain devices are available, may proceed in autonomous control mode. Besides, it is capable of moving within narrow fairways. The cruise speed of a sailing boat and wind-motored ship were compared provided that the wind velocity direction changes along a harmonic law with regard to the motion direction. Mean dimensionless speed of the wind-motored ship appears to be by 20--25% higher than that of a sailing boat. There was analyzed a possibility of using the wind motors on planet rovers in Mars or Venus atmospheric conditions. A Mars rover power and motor system has been assessed for the power level of 3 kW.

  9. Acute motor axonal neuropathy cases in Van region.

    PubMed

    Sayin, R; Tombul, T; Gulec, T C; Anlar, O; Akbayram, S; Caksen, H

    2011-01-01

    Acute motor axonal neuropathy (AMAN) is a form of Guillain Barré Syndrome (GBS) seen in summer months in Northern China to cause epidemics. This form of the disease, which is also sporadically observed in other countries, constitutes less than 5% of GBS in Western countries. It usually develops with motor findings. No sensory findings are observed. In some of the cases, the severe impairments in tissues improve however slowly and inadequately. In the motor conduction studies of cases with AMAN, motor action potential values are lowered. On needle electromyography (EMG), motor unit potential (MUP) activity is diminished with spontaneous denervation findings. Investigations were conducted on nerve conduction of patients with GBS aged from 1 to 77 years. AMAN was detected in 25 of these patients. In our investigation, AMAN as a GBS variant was detected in 39.7% of the patients. The conduction velocities of motor nerves were in normal ranges whereas combined muscle action potentials were significantly lower. No F response could be obtained. Although AMAN is a rare variant of GBS and shows different clinical courses, it has been brought under intense scrutiny since there is high prevalance of acute inflammatory neuropathies in our region (Tab. 1, Ref. 7).

  10. Dynamic instability of collective myosin II motors

    NASA Astrophysics Data System (ADS)

    Li, Jin-Fang; Wang, Zi-Qing; Li, Qi-Kun; Xing, Jian-Jun; Wang, Guo-Dong

    2016-11-01

    Some kinds of muscles can oscillate spontaneously, which is related to the dynamic instability of the collective motors. Based on the two-state ratchet model and with consideration of the motor stiffness, the dynamics of collective myosin II motors are studied. It is shown that when the motor stiffness is small, the velocity of the collective motors decreases monotonically with load increasing. When the motor stiffness becomes large, dynamic instability appears in the force-velocity relationship of the collective-motor transport. For a large enough motor stiffness, the zero-velocity point lies in the unstable range of the force-velocity curve, and the motor system becomes unstable before the motion is stopped, so spontaneous oscillations can be generated if the system is elastically coupled to its environment via a spring. The oscillation frequency is related to the motor stiffness, motor binding rate, spring stiffness, and the width of the ATP excitation interval. For a medium motor stiffness, the zero-velocity point lies outside the unstable range of the force-velocity curve, and the motion will be stopped before the instability occurs. Project supported by the National Natural Science Foundation of China (Grant No. 11205123).

  11. Molecular Motors and Stochastic Models

    NASA Astrophysics Data System (ADS)

    Lipowsky, Reinhard

    The behavior of single molecular motors such as kinesin or myosin V, which move on linear filaments, involves a nontrivial coupling between the biochemical motor cycle and the stochastic movement. This coupling can be studied in the framework of nonuniform ratchet models which are characterized by spatially localized transition rates between the different internal states of the motor. These models can be classified according to their functional relationships between the motor velocity and the concentration of the fuel molecules. The simplest such relationship applies to two subclasses of models for dimeric kinesin and agrees with experimental observations on this molecular motor.

  12. Motor sequence learning and motor adaptation in primary cervical dystonia.

    PubMed

    Katschnig-Winter, Petra; Schwingenschuh, Petra; Davare, Marco; Sadnicka, Anna; Schmidt, Reinhold; Rothwell, John C; Bhatia, Kailash P; Edwards, Mark J

    2014-06-01

    Motor sequence learning and motor adaptation rely on overlapping circuits predominantly involving the basal ganglia and cerebellum. Given the importance of these brain regions to the pathophysiology of primary dystonia, and the previous finding of abnormal motor sequence learning in DYT1 gene carriers, we explored motor sequence learning and motor adaptation in patients with primary cervical dystonia. We recruited 12 patients with cervical dystonia and 11 healthy controls matched for age. Subjects used a joystick to move a cursor from a central starting point to radial targets as fast and accurately as possible. Using this device, we recorded baseline motor performance, motor sequence learning and a visuomotor adaptation task. Patients with cervical dystonia had a significantly higher peak velocity than controls. Baseline performance with random target presentation was otherwise normal. Patients and controls had similar levels of motor sequence learning and motor adaptation. Our patients had significantly higher peak velocity compared to controls, with similar movement times, implying a different performance strategy. The preservation of motor sequence learning in cervical dystonia patients contrasts with the previously observed deficit seen in patients with DYT1 gene mutations, supporting the hypothesis of differing pathophysiology in different forms of primary dystonia. Normal motor adaptation is an interesting finding. With our paradigm we did not find evidence that the previously documented cerebellar abnormalities in cervical dystonia have a behavioral correlate, and thus could be compensatory or reflect "contamination" rather than being directly pathological.

  13. Piezoceramic Ultrasonic Motor Technology

    SciTech Connect

    Burden, J.S.

    1999-02-24

    The objective of this project was to team Aerotech and AlliedSignal FM and T (AS) to develop a cost-efficient process for small-batch, high performance PZT motor production. Aerotech would acquire the basic process expertise in motor fabrication, assembly, and testing from AS. Together, Aerotech and AS were to identify appropriate process improvements, focusing on raw material quality, manufacturing processes, and durability assessment. Aerotech would then design and build a motor in consultation with AS. Aerotech engineering observed motor manufacturing in the AS piezo lab and worked side by side with AS personnel to build and test a prototype motor to facilitate learning the technology. Using information from AS and hands-on experience with the AS motor drive system enabled Aerotech to design and build its own laboratory drive system to operate motors. The team compiled information to establish a potential piezo motor users' list, and an intellectual property search was conducted to understand current patent and IP (intellectual property) status of motor design. Work was initiated to identify and develop an American source for piezo motor elements; however, due to manpower restraints created by the resignation of the AS Ph.D. ceramist responsible for these tasks, the project schedule slipped. The project was subsequently terminated before significant activities were accomplished. AS did, however, provide Aerotech with contacts in Japanese industry that are willing and capable of supplying them with special design motor elements.

  14. Shock wave over hand muscles: a neurophysiological study on peripheral conduction nerves in normal subjects

    PubMed Central

    Manganotti, Paolo; Amelio, Ernesto; Guerra, Claudio

    2012-01-01

    Summary Background and purpose: shock waves are defined as a sequence of single sonic pulses largely used in the treatment of bone and tendon diseases and recently on muscular hypertonia in stroke patients. Our purpose is to investigate the short and long term effect of extra-corporeal shock wave therapy (ESWT) on the peripheral nerve conduction and central conductions from the treated muscles in normal human subjects in order to define safety criteria. Methods: we studied 10 patients normal subjects. Motor and sensory nerve conduction velocity and F response from right ipothenar eminence (abductor digiti minimi) of the hand was recorded. Furthermore MEP latency and amplitude and central conduction from the same muscles by transcranial magnetic stimulation was evaluated. In all subjects each neurophysiological measures were monitored before, immediately after, 15 minutes and after 30 minutes from the active ESWT treatment (1600 shots with an energy applied of 0.030 mj/mm2). Results: no significant short or long term changes were noted in sensory and motor peripheral nerve conduction and in central motor conduction in all the subjects evaluated after ESWT. Conclusions: the ESWT has no effect on sensory and motor peripheral nerve conduction and in central motor conduction. The ESWT using low level of energy represent a safety method for treating the muscles in human subjects without involvement of motor or sensory nervous trunks. Different mechanisms of action of ESWT are discussed. PMID:23738282

  15. Conduction Aphasia, Sensory-Motor Integration, and Phonological Short-Term Memory--An Aggregate Analysis of Lesion and fMRI Data

    ERIC Educational Resources Information Center

    Buchsbaum, Bradley R.; Baldo, Juliana; Okada, Kayoko; Berman, Karen F.; Dronkers, Nina; D'Esposito, Mark; Hickok, Gregory

    2011-01-01

    Conduction aphasia is a language disorder characterized by frequent speech errors, impaired verbatim repetition, a deficit in phonological short-term memory, and naming difficulties in the presence of otherwise fluent and grammatical speech output. While traditional models of conduction aphasia have typically implicated white matter pathways,…

  16. Transport efficiency of membrane-anchored kinesin-1 motors depends on motor density and diffusivity.

    PubMed

    Grover, Rahul; Fischer, Janine; Schwarz, Friedrich W; Walter, Wilhelm J; Schwille, Petra; Diez, Stefan

    2016-11-15

    In eukaryotic cells, membranous vesicles and organelles are transported by ensembles of motor proteins. These motors, such as kinesin-1, have been well characterized in vitro as single molecules or as ensembles rigidly attached to nonbiological substrates. However, the collective transport by membrane-anchored motors, that is, motors attached to a fluid lipid bilayer, is poorly understood. Here, we investigate the influence of motors' anchorage to a lipid bilayer on the collective transport characteristics. We reconstituted "membrane-anchored" gliding motility assays using truncated kinesin-1 motors with a streptavidin-binding peptide tag that can attach to streptavidin-loaded, supported lipid bilayers. We found that the diffusing kinesin-1 motors propelled the microtubules in the presence of ATP. Notably, we found the gliding velocity of the microtubules to be strongly dependent on the number of motors and their diffusivity in the lipid bilayer. The microtubule gliding velocity increased with increasing motor density and membrane viscosity, reaching up to the stepping velocity of single motors. This finding is in contrast to conventional gliding motility assays where the density of surface-immobilized kinesin-1 motors does not influence the microtubule velocity over a wide range. We reason that the transport efficiency of membrane-anchored motors is reduced because of their slippage in the lipid bilayer, an effect that we directly observed using single-molecule fluorescence microscopy. Our results illustrate the importance of motor-cargo coupling, which potentially provides cells with an additional means of regulating the efficiency of cargo transport.

  17. N10 potential as an antidromic motor evoked potential in a median nerve short-latency somatosensory evoked potential study.

    PubMed

    Inoue, Ken; Mimori, Yasuyo; Nakamura, Shigenobu

    2002-01-01

    When stimulating the mixed nerve to record evoked potential, both sensory and motor fibers are activated before entering the spinal cord. The N10 potential has been described as an antidromic motor evoked potential based on results obtained by recording at the anterior midneck. In the present study, we examined the changes in latencies of Erb's potential, N10, and N13 by stimulating the median nerve distally at the wrist and proximally at the elbow. The conduction velocity of N10 calculated by the difference between N10 latencies at the two stimulation points was consistent with motor conduction velocity, although N13 conduction velocity estimated by the same method reflected a sensory conduction velocity. A positive relation was also observed between the indirect latency from the stimulation point to the anterior root as calculated using the equation (F - M - 1) / 2 (ms) and the direct latency to the negative peak of the N10 potential. Our data support the notion that N10 represents antidromic motor potential originating in the spinal entry zone of the anterior root.

  18. The effects of dietary treatment with essential fatty acids on sciatic nerve conduction and activity of the Na+/K+ pump in streptozotocin-diabetic rats.

    PubMed Central

    Lockett, M. J.; Tomlinson, D. R.

    1992-01-01

    1. This study examined the effects of dietary essential fatty acid supplementation (5% (w/w) evening primrose oil) upon sciatic motor nerve conduction velocity and 86Rb+ pumping in sciatic nerve endoneurial preparations in rats with 4 to 5 weeks of streptozotocin-induced diabetes. 2. Control diabetic rats (dietary supplementation with 5% (w/w) hydrogenated coconut oil) exhibited a reduction in motor nerve conduction velocity (16%; P less than 0.05) compared to similarly-fed non-diabetic controls, but there was no significant alteration in ouabain-sensitive 86Rb+ pumping, a parameter reflecting activity of the Na+/K+ pump. 3. Treatment of diabetic rats with evening primrose oil prevented completely the development of the motor nerve conduction velocity deficit without affecting the severity of diabetes. Evening primrose oil treatment did not significantly affect motor nerve conduction velocity of non-diabetic animals. 4. Evening primrose oil treatment caused a significant reduction in activity of the Na+/K+ pump in sciatic nerves of diabetic animals (45%; P less than 0.05). 5. These results suggest that the acute conduction velocity defect arising in streptozotocin-diabetic rats, and the actions of evening primrose oil upon this, are independent of any effect on activity of the Na+/K+ pump. Other putative mechanisms are discussed. PMID:1313726

  19. MOTOR SKILLS AND NUTRITIONAL STATUS OUTCOMES FROM A PHYSICAL ACTIVITY INTERVENTION IN SHORT BREAKS ON PRESCHOOL CHILDREN CONDUCTED BY THEIR EDUCATORS: A PILOT STUDY.

    PubMed

    Monsalves-Alvarez, Matias; Castro-Sepulveda, Mauricio; Zapata-Lamana, Rafael; Rosales-Soto, Giovanni; Salazar, Gabriela

    2015-10-01

    Introducción: la obesidad infantil es ya un problema de salud pública. Para su disminución, han sido planteadas diferentes estrategias con el fin de aumentar la actividad física y con ello reducir la ganancia de peso en niños; estas estrategias se han llevado a cabo con un éxito limitado. Objetivo: el objetivo de este estudio es evaluar los resultados de una intervención piloto, la cual consiste en tres recreos de 15 minutos tres veces por semana conducidos por las educadoras y guiados por educadores físicos en los patrones motores y el estado nutricional de niños preescolares. Métodos: la muestra consta de 70 niños preescolares (32 niños y 38 niñas), edad 4 ± 0.6. Las clases de educación física fueron llevadas a cabo tres veces por semana en recreos de 15 minutos. Se plantearon circuitos, los cuales contenían saltos, gateo, galopes, carreras, carga y manipulación de balones medicinales. Las pruebas motoras evaluadas fueron el salto horizontal y la carrera de 12 metros. Resultados: con la intervención no se encontraron diferencias significativas en el estado nutricional (media Z score niños p = 0,49, media Z score niñas p = 0,77). Sí se encontró un aumento significativo en el peso (p < 0,0001) y la talla ( p < 0,0001) tanto en niños como en niñas al término de la intervención. En cuanto a las pruebas motoras, la carrera de 12 metros ajustada al peso tuvo cambios significativos en niños (p = 0,002) y en niñas ( p < 0,0001); mientras que el salto horizontal mejoró en ambos grupos tras la intervención (p < 0,0001). Cuando se ajustaron las pruebas motoras por estado nutricional, se encontraron cambios significativos tanto en la carrera de 12 metros en los niños con sobrepeso (p = 0,008) como en el salto horizontal/talla (p < 0,0001), lo que sugiere el incremento de la potencia independientemente del aumento de peso observado. Conclusión: este estudio piloto encontró que una intervención con actividades más intensas en peque

  20. The mechanochemistry of molecular motors.

    PubMed Central

    Keller, D; Bustamante, C

    2000-01-01

    A theory of molecular motors is presented that explains how the energy released in single chemical reactions can generate mechanical motion and force. In the simplest case the fluctuating movements of a motor enzyme are well described by a diffusion process on a two-dimensional potential energy surface, where one dimension is a chemical reaction coordinate and the other is the spatial displacement of the motor. The coupling between chemistry and motion results from the shape of the surface, and motor velocities and forces result from diffusion currents on this surface. This microscopic description is shown to possess an equivalent kinetic mechanism in which the rate constants depend on externally applied forces. By using this equivalence we explore the characteristic properties of several broad classes of motor mechanisms and give general expressions for motor velocity versus load force for any member of each class. We show that in some cases simple plots of 1/velocity vs. 1/concentration can distinguish between classes of motor mechanisms and may be used to determine the step at which movement occurs. PMID:10653770

  1. Locomotion of chemically powered autonomous nanowire motors

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Li, Longqiu; Li, Tianlong; Zhang, Guangyu; Sun, Qian

    2015-08-01

    Physical insights on the hydrodynamics and locomotion of self-propelled nanowire motor under nonequilibrium steady state are investigated using finite element method in accordance with hybrid molecular dynamics/multiparticle collision dynamics and rigid body dynamics. Nanowire motor is discretized into finite segments, and forces of solvent molecule acting on the motor are assumed to be the sum of forces acting on all segments of the motor. We show that the locomotion of nanowire motor is mainly determined by the imbalance forces acting on the catalytic and noncatalytic segments. The average velocity along the axis increases significantly as a function of time prior to reaching equilibrium. The length of nanowire motor shows negligible effect on the velocity of the motor. Preliminary experimental results are provided to validate the current model.

  2. Theta-burst stimulation over primary motor cortex degrades early motor learning.

    PubMed

    Iezzi, Ennio; Suppa, Antonio; Conte, Antonella; Agostino, Rocco; Nardella, Andrea; Berardelli, Alfredo

    2010-02-01

    Theta-burst stimulation (TBS) is currently used for inducing long-lasting changes in primary motor cortex (M1) excitability. More information is needed on how M1 is involved in early motor learning (practice-related improvement in motor performance, motor retention and motor consolidation). We investigated whether inhibitory continuous TBS (cTBS) is an effective experimental approach for modulating early motor learning of a simple finger movement in healthy humans. In a short task, 11 subjects practised 160 movements, and in a longer task also testing motor consolidation ten subjects practised 600 movements. During both experiments subjects randomly received real or sham cTBS over the left M1. Motor evoked potentials were tested at baseline and 7 min after cTBS. In the 160-movement experiment to test motor retention, 20 movements were repeated 30 min after motor practice ended. In the 600-movement experiment motor retention was assessed 15 and 30 min after motor practice ended, motor consolidation was tested by performing 20 movements 24 h after motor practice ended. Kinematic variables - movement amplitude, peak velocity and peak acceleration - were measured. cTBS significantly reduced the practice-related improvement in motor performance of finger movements in the experiment involving 160 movements and in the first part of the experiment involving 600 movements. After cTBS, peak velocity and peak acceleration of the 20 movements testing motor retention decreased whereas those testing motor consolidation remained unchanged. cTBS over M1 degrades practice-related improvement in motor performance and motor retention, but not motor consolidation of a voluntary finger movement.

  3. Distinct transport regimes for two elastically coupled molecular motors.

    PubMed

    Berger, Florian; Keller, Corina; Klumpp, Stefan; Lipowsky, Reinhard

    2012-05-18

    Cooperative cargo transport by two molecular motors involves an elastic motor-motor coupling, which can reduce the motors' velocity and/or enhance their unbinding from the filament. We show theoretically that these interference effects lead, in general, to four distinct transport regimes. In addition to a weak coupling regime, kinesin and dynein motors are found to exhibit a strong coupling and an enhanced unbinding regime, whereas myosin motors are predicted to attain a reduced velocity regime. All of these regimes, which we derive by explicit calculations and general time scale arguments, can be explored experimentally by varying the elastic coupling strength.

  4. Twitch and tetanic properties of human thenar motor units paralyzed by chronic spinal cord injury.

    PubMed

    Häger-Ross, C K; Klein, C S; Thomas, C K

    2006-07-01

    Little is known about how human motor units respond to chronic paralysis. Our aim was to record surface electromyographic (EMG) signals, twitch forces, and tetanic forces from paralyzed motor units in the thenar muscles of individuals (n = 12) with chronic (1.5-19 yr) cervical spinal cord injury (SCI). Each motor unit was activated by intraneural stimulation of its motor axon using single pulses and trains of pulses at frequencies between 5 and 100 Hz. Paralyzed motor units (n = 48) had small EMGs and weak tetanic forces (n = 32 units) but strong twitch forces, resulting in half-maximal force being achieved at a median of only 8 Hz. The distributions for cumulative twitch and tetanic forces also separated less for paralyzed units than for control units, indicating that increases in stimulation frequency made a smaller relative contribution to the total force output in paralyzed muscles. Paralysis also induced slowing of conduction velocities, twitch contraction times and EMG durations. However, the elevated ratios between the twitch and the tetanic forces, but not contractile speed, correlated significantly with the extent to which unit force summated in response to different frequencies of stimulation. Despite changes in the absolute values of many electrical and mechanical properties of paralyzed motor units, most of the distributions shifted uniformly relative to those of thenar units obtained from control subjects. Thus human thenar muscles paralyzed by SCI retain a population of motor units with heterogeneous contractile properties because chronic paralysis influenced all of the motor units similarly.

  5. Segmented rail linear induction motor

    DOEpatents

    Cowan, Jr., Maynard; Marder, Barry M.

    1996-01-01

    A segmented rail linear induction motor has a segmented rail consisting of a plurality of nonferrous electrically conductive segments aligned along a guideway. The motor further includes a carriage including at least one pair of opposed coils fastened to the carriage for moving the carriage. A power source applies an electric current to the coils to induce currents in the conductive surfaces to repel the coils from adjacent edges of the conductive surfaces.

  6. Segmented rail linear induction motor

    DOEpatents

    Cowan, M. Jr.; Marder, B.M.

    1996-09-03

    A segmented rail linear induction motor has a segmented rail consisting of a plurality of nonferrous electrically conductive segments aligned along a guideway. The motor further includes a carriage including at least one pair of opposed coils fastened to the carriage for moving the carriage. A power source applies an electric current to the coils to induce currents in the conductive surfaces to repel the coils from adjacent edges of the conductive surfaces. 6 figs.

  7. State observer for synchronous motors

    DOEpatents

    Lang, Jeffrey H.

    1994-03-22

    A state observer driven by measurements of phase voltages and currents for estimating the angular orientation of a rotor of a synchronous motor such as a variable reluctance motor (VRM). Phase voltages and currents are detected and serve as inputs to a state observer. The state observer includes a mathematical model of the electromechanical operation of the synchronous motor. The characteristics of the state observer are selected so that the observer estimates converge to the actual rotor angular orientation and velocity, winding phase flux linkages or currents.

  8. Hall effect encoding of brushless dc motors

    NASA Technical Reports Server (NTRS)

    Berard, C. A.; Furia, T. J.; Goldberg, E. A.; Greene, R. C.

    1970-01-01

    Encoding mechanism integral to the motor and using the permanent magnets embedded in the rotor eliminates the need for external devices to encode information relating the position and velocity of the rotating member.

  9. Motor syndromes.

    PubMed

    Corea, Francesco; Micheli, Sara

    2012-01-01

    Motor disturbances alone or associated with other focal deficits are the most common symptoms suggesting a neurovascular event. An appropriate clinical assessment of these signs and symptoms may help physicians to better diagnose and to both better treat and predict outcome. In this paper the main clinical features of motor deficit are described together with other motor-related events such as ataxia and movement disturbances.

  10. Immunity to nerve growth factor and the effect on motor unit reinnervation in the rabbit.

    PubMed

    Finkelstein, D I; Luff, A R; Schuijers, J A

    1992-05-01

    The trophic effects of nerve growth factor (NGF) on sympathetic, peripheral afferent, and other neural crest-derived cells have been intensively investigated. More recently, NGF has been shown to have an influence on motoneurons. This study was undertaken to investigate whether NGF had any influence on the mechanical or histological properties of reinnervated motor units. Three groups of rabbits were used: normal rabbits, rabbits in which the nerve to medial gastrocnemius (MG) was cut and allowed to reinnervate for 56 days, and rabbits in which the MG nerve reinnervated in the presence of immunity to NGF. Immunity to NGF did not affect the ability of motor axons to reinnervate a muscle, nor were the contractile characteristics of the motor units altered. The size of horseradish peroxidase-labeled motoneurons was not influenced by immunization against NGF; however, the distribution of afferent neuron sizes was altered. Conduction velocity of motor axons proximal to the neuroma was significantly faster after immunization against NGF. Transection and subsequent reinnervation by a peripheral nerve normally causes an increase in myelin thickness proximal to the neuroma. However, immunization against NGF appeared to decrease the magnitude of myelin thickening. It was concluded that immunization against NGF affects motor axonal conduction velocity via an influence on the neural crest-derived Schwann cells.

  11. Optimal working frequency of ultrasonic motors.

    PubMed

    Shi, Weijia; Zhao, Hui; Ma, Jie; Yao, Yu

    2016-08-01

    In this work, the existence of the optimal working frequency for ultrasonic motors (USMs) is theoretically and experimentally verified for the first time, at which working point the power dissipation of the motors arrives at its minimum value. The mathematical model of the mechanical quality factor is initially deduced to evaluate the loss level, because it shows an opposite tendency with losses. The derivative of the mechanical quality factor can be subsequently arrived at with the aid of the phenomenon model of the phase of the admittance. The theoretical derivation infers that the maximum value of the mechanical quality factor exists almost around the average value of the frequency of maximum conductance and the frequency of maximum resistance. Then the input power of the USM is measured under the constant velocity condition, which is supposed to counteract the loss; that is, the loss can be therefore evaluated experimentally. Measurements infer that the power dissipation of the motor reaches the minimum value around the calculated optimal working frequency. In other word, it is proven that the USM maintains an optimal working frequency from the loss reduction view point.

  12. [An analysis of characteristics of nerve conduction in 154 cases of amyotrophic lateral sclerosis].

    PubMed

    Ren, Y T; Cui, F; Yang, F; Chen, Z H; Ling, L; Huang, X S

    2016-10-01

    Objective: To analyze the features of nerve conduction in patients with amyotrophic lateral sclerosis (ALS), and explore the correlation between compound muscle action potential (CMAP) amplitude and disease duration and revised amyotrophic lateral sclerosis functional rating scale (ALSFRS-R). Methods: Standard motor and sensory nerve conduction studies were performed in 154 patients with ALS. The following parameters were collected including CMAP amplitude, distal motor latency (DML), motor conduction velocity, sensory conduction velocity and sensory nerve action potential amplitude. Regression study was done to explore the correlation between CMAP amplitude and disease duration and ALSFRS-R. Results: Motor nerve conduction abnormalities were presented in a majority of the patients with prolonged DML in the tibial nerve, median nerve and ulnar nerve as the most common form (61.06%-81.42%), followed by decreased CMAP amplitude (30.12%-53.98%), decreased MCV (12.05%-16.81%) and absence of CMAP (2.65%-9.73%). Sensory nerve conduction abnormalities were detected in a small proportion of patients and the decreased SCV, decreased SNAP amplitude and absence of SNAP in the sural nerve, median nerve and ulnar nerve were found in 1.22%-2.73%, 0-1.82% and 0-1.22% patients respectively. No correlation was found between CMAP of the common peroneal nerve, tibial nerve, median nerve and ulnar nerve and the disease duration (P>0.05), while significant positive correlation was established between CMAP amplitude of the median nerve and ulnar nerve and ALSFRS-R (r=0.273, P=0.016; r=0.357, P=0.001). Conclusions: Motor nerve conduction is abnormal in a majority of ALS patients with prolonged DML as the most common form, while abnormal sensory nerve conduction is only found in a few of ALS patients. CMAP amplitude of the median nerve and ulnar nerve might be of certain clinical value in evaluating the severity of ALS.

  13. Dynamics of Motorized Vehicle Flow under Mixed Traffic Circumstance

    NASA Astrophysics Data System (ADS)

    Guo, Hong-Wei; Gao, Zi-You; Zhao, Xiao-Mei; Xie, Dong-Fan

    2011-04-01

    To study the dynamics of mixed traffic flow consisting of motorized and non-motorized vehicles, a car-following model based on the principle of collision free and cautious driving is proposed. Lateral friction and overlapping driving are introduced to describe the interactions between motorized vehicles and non-motorized vehicles. By numerical simulations, the flux-density relation, the temporal-spatial dynamics, and the velocity evolution are investigated in detail. The results indicate non-motorized vehicles have a significant impact on the motorized vehicle flow and cause the maximum flux to decline by about 13%. Non-motorized vehicles can decrease the motorized vehicle velocity and cause velocity oscillation when the motorized vehicle density is low. Moreover, non-motorized vehicles show a significant damping effect on the oscillating velocity when the density is medium and high, and such an effect weakens as motorized vehicle density increases. The results also stress the necessity for separating motorized vehicles from non-motorized vehicles.

  14. Molecular motors

    NASA Astrophysics Data System (ADS)

    Allemand, Jean François Desbiolles, Pierre

    2015-10-01

    How do we move? More precisely, what are the molecular mechanisms that can explain that our muscles, made of very small components can move at a osopic scale? To answer these questions we must introduce molecular motors. Those motors are proteins, or small protein assemblies that, in our cells, transform chemical energy into mechanical work. Then, like we could do for a oscopic motor, used in a car or in a fan, we are going to study the basic behavior of these molecular machines, present what are their energy sources, calculate their power, their yield. If molecular motors are crucial for our oscopic movements, we are going to see that they are also essential to cellular transport and that considering the activity of some enzymes as molecular motors bring some interesting new insights on their activity.

  15. Motor imagery facilitates force field learning.

    PubMed

    Anwar, Muhammad Nabeel; Tomi, Naoki; Ito, Koji

    2011-06-13

    Humans have the ability to produce an internal reproduction of a specific motor action without any overt motor output. Recent findings show that the processes underlying motor imagery are similar to those active during motor execution and both share common neural substrates. This suggests that the imagery of motor movements might play an important role in acquiring new motor skills. In this study we used haptic robot in conjunction with motor imagery technique to improve learning in a robot-based adaptation task. Two groups of subjects performed reaching movements with or without motor imagery in a velocity-dependent and position-dependent mixed force field. The groups performed movements with motor imagery produced higher after effects and decreased muscle co-contraction with respect to no-motor imagery group. These results showed a positive influence of motor imagery on acquiring new motor skill and suggest that motor learning can be facilitated by mental practice and could be used to increase the rate of adaptation.

  16. The Relationship between Nerve Conduction Study and Clinical Grading of Carpal Tunnel Syndrome

    PubMed Central

    Cheluvaiah, Janardhan D.; Agadi, Jagadish B.; Nagaraj, Karthik

    2016-01-01

    Introduction Carpal Tunnel Syndrome (CTS) is the most common nerve entrapment. Subjective sensory symptoms are common place in patients with CTS, but sometimes they are not supported by objective findings in the neurological examination. Electrodiagnostic (EDx) studies are a valid and reliable means of confirming the diagnosis. The amplitudes along with the conduction velocities of the sensory nerve action potential and motor nerve action potential reflect the functional state of axons, and are useful parameters and complement the clinical grading in the assessment of severity of CTS. Aim To conduct median nerve sensory and motor conduction studies on patients with carpal tunnel syndrome and correlate the relationship between nerve conduction study parameters and the clinical severity grading. Materials and Methods Based on clinical assessment, the study patients were divided into 03 groups with mild CTS, moderate CTS and severe CTS respectively as per Mackinnson’s classification. Median and ulnar nerve conduction studies were performed on bilateral upper limbs of 50 patients with symptoms of CTS and 50 age and sex matched healthy control subjects. The relationship between the clinical severity grade and various nerve conduction study parameters were correlated. Results In this prospective case control study, 50 patients with symptoms consistent with CTS and 50 age and sex matched healthy control subjects were examined over a 10 month period. A total of 30 patients had unilateral CTS (right upper limb in 19 and left upper limb in 11) and 20 patients had bilateral CTS. Female to male ratio was 3.54 to 1. Age ranged from 25 to 81 years. The mean age at presentation was 49.68±11.7 years. Tingling paresthesias of hand and first three fingers were the most frequent symptoms 48 (98%). Tinel’s and Phalen’s sign were positive in 36 (72%) and 44 (88%) patients respectively. The mean duration of symptoms at presentation was 52.68±99.81 weeks. 16 patients (32%) had

  17. Linear Motor With Air Slide

    NASA Technical Reports Server (NTRS)

    Johnson, Bruce G.; Gerver, Michael J.; Hawkey, Timothy J.; Fenn, Ralph C.

    1993-01-01

    Improved linear actuator comprises air slide and linear electric motor. Unit exhibits low friction, low backlash, and more nearly even acceleration. Used in machinery in which positions, velocities, and accelerations must be carefully controlled and/or vibrations must be suppressed.

  18. Center of pressure velocity reflects body acceleration rather than body velocity during quiet standing.

    PubMed

    Masani, Kei; Vette, Albert H; Abe, Masaki O; Nakazawa, Kimitaka

    2014-03-01

    The purpose of this study was to test the hypothesis that the center of pressure (COP) velocity reflects the center of mass (COM) acceleration due to a large derivative gain in the neural control system during quiet standing. Twenty-seven young (27.2±4.5 years) and twenty-three elderly (66.2±5.0 years) subjects participated in this study. Each subject was requested to stand quietly on a force plate for five trials, each 90 s long. The COP and COM displacements, the COP and COM velocities, and the COM acceleration were acquired via a force plate and a laser displacement sensor. The amount of fluctuation of each variable was quantified using the root mean square. Following the experimental study, a simulation study was executed to investigate the experimental findings. The experimental results revealed that the COP velocity was correlated with the COM velocity, but more highly correlated with the COM acceleration. The equation of motion of the inverted pendulum model, however, accounts only for the correlation between the COP and COM velocities. These experimental results can be meaningfully explained by the simulation study, which indicated that the neural motor command presumably contains a significant portion that is proportional to body velocity. In conclusion, the COP velocity fluctuation reflects the COM acceleration fluctuation rather than the COM velocity fluctuation, implying that the neural motor command controlling quiet standing posture contains a significant portion that is proportional to body velocity.

  19. Stepper motor

    NASA Technical Reports Server (NTRS)

    Dekramer, Cornelis

    1994-01-01

    The purpose of this document is to describe the more commonly used permanent magnet stepper motors for spaceflight. It will discuss the mechanical and electrical aspects of the devices, their torque behavior, those parameters which need to be controlled and measured, and test methods to be employed. It will also discuss torque margins, compare these to the existing margin requirements, and determine the applicability of these requirements. Finally it will attempt to generate a set of requirements which will be used in any stepper motor procurement and will fully characterize the stepper motor behavior in a consistent and repeatable fashion.

  20. Molecular Motors: Power Strokes Outperform Brownian Ratchets.

    PubMed

    Wagoner, Jason A; Dill, Ken A

    2016-07-07

    Molecular motors convert chemical energy (typically from ATP hydrolysis) to directed motion and mechanical work. Their actions are often described in terms of "Power Stroke" (PS) and "Brownian Ratchet" (BR) mechanisms. Here, we use a transition-state model and stochastic thermodynamics to describe a range of mechanisms ranging from PS to BR. We incorporate this model into Hill's diagrammatic method to develop a comprehensive model of motor processivity that is simple but sufficiently general to capture the full range of behavior observed for molecular motors. We demonstrate that, under all conditions, PS motors are faster, more powerful, and more efficient at constant velocity than BR motors. We show that these differences are very large for simple motors but become inconsequential for complex motors with additional kinetic barrier steps.

  1. A sensory-motor control model of animal flight explains why bats fly differently in light versus dark.

    PubMed

    Bar, Nadav S; Skogestad, Sigurd; Marçal, Jose M; Ulanovsky, Nachum; Yovel, Yossi

    2015-01-01

    Animal flight requires fine motor control. However, it is unknown how flying animals rapidly transform noisy sensory information into adequate motor commands. Here we developed a sensorimotor control model that explains vertebrate flight guidance with high fidelity. This simple model accurately reconstructed complex trajectories of bats flying in the dark. The model implies that in order to apply appropriate motor commands, bats have to estimate not only the angle-to-target, as was previously assumed, but also the angular velocity ("proportional-derivative" controller). Next, we conducted experiments in which bats flew in light conditions. When using vision, bats altered their movements, reducing the flight curvature. This change was explained by the model via reduction in sensory noise under vision versus pure echolocation. These results imply a surprising link between sensory noise and movement dynamics. We propose that this sensory-motor link is fundamental to motion control in rapidly moving animals under different sensory conditions, on land, sea, or air.

  2. The Study of Diagnostic Efficacy of Nerve Conduction Study Parameters in Cervical Radiculopathy

    PubMed Central

    Pawar, Sachin; Kashikar, Aditi; Shende, Vinod; Waghmare, Satish

    2013-01-01

    Background: Cervical Radiculopathy (CR) is a neurologic condition characterised by dysfunction of a cervical spinal nerve, the roots of the nerve, or both. Diagnostic criteria for CR are not well defined, and no universally accepted criteria for its diagnosis have been established. Clinical examination, radiological imaging and electrophysiologic evaluation are the different modalities to diagnose CR. The incidence of Cervical Spondylosis and related conditions is increasing in the present scenario and the use of radiologic examination is time consuming and uneconomical for the common Indian setup. Thus, there is a definite need to establish a cost effective, reliable, and accurate means for establishing the diagnosis of cervical radiculopathy. Electrodiagnostic tests are the closest to fulfill these criteria. Aim: To evaluate diagnostic utility of various motor and sensory nerve conduction study parameters in cervical radiculopathy. Setting and Design: It was a cross-sectional study conducted on 100 subjects of age > 40 years. Material and Methods: The consecutive patients clinically diagnosed to have cervical radiculopathy, referred from department of Orthopaedics were prospectively recruited for the motor and sensory nerve conduction study using RMS EMG EP Mark-II. Parameters studied were Compound Muscle Action Potential (CMAP), Distal Motor Latency (DML) and Conduction Velocity (CV) for motor nerves and Sensory Nerve Action Potential (SNAP) and CV for sensory nerves. Statistical Analysis: Study observations and results were analysed to find the Specificity, Sensitivity, Positive Predictive Value and Negative Predictive Value using SPSS 16.0. Results: Among various motor nerve conduction parameters CMAP was found to be more sensitive with high positive predicative value. CV was found to have greater specificity and DML had least negative predictive value. Sensory nerve conduction parameters were found to have less sensitivity but higher specificity as compared

  3. Advanced Motors

    SciTech Connect

    Knoth, Edward A; Chelluri, Bhanumathi; Schumaker, Edward J

    2012-12-14

    vProject Summary Transportation energy usage is predicted to increase substantially by 2020. Hybrid vehicles and fuel cell powered vehicles are destined to become more prominent as fuel prices rise with the demand. Hybrid and fuel cell vehicle platforms are both dependent on high performance electric motors. Electric motors for transportation duty will require sizeable low-speed torque to accelerate the vehicle. As motor speed increases, the torque requirement decreases which results in a nearly constant power motor output. Interior permanent magnet synchronous motors (IPMSM) are well suited for this duty. , , These rotor geometries are configured in straight lines and semi circular arc shapes. These designs are of limited configurations because of the lack of availability of permanent magnets of any other shapes at present. We propose to fabricate rotors via a novel processing approach where we start with magnet powders and compact them into a net shape rotor in a single step. Using this approach, widely different rotor designs can be implemented for efficiency. The current limitation on magnet shape and thickness will be eliminated. This is accomplished by co-filling magnet and soft iron powders at specified locations in intricate shapes using specially designed dies and automatic powder filling station. The process fundamentals for accomplishing occurred under a previous Applied Technology Program titled, Motors and Generators for the 21st Century. New efficient motor designs that are not currently possible (or cost prohibitive) can be accomplished by this approach. Such an approach to motor fabrication opens up a new dimension in motor design. Feasibility Results We were able to optimize a IPMSM rotor to take advantage of the powder co-filling and DMC compaction processing methods. The minimum low speed torque requirement of 5 N-m can be met through an optimized design with magnet material having a Br capability of 0.2 T. This level of magnetic performance can

  4. 48 CFR 945.570-8 - Reporting motor vehicle data.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Reporting motor vehicle... Reporting motor vehicle data. (a) Contractors conducting motor vehicle operations shall forward annually (on or before December 1) to the contracting officer their plan for acquisition of motor vehicles for...

  5. 48 CFR 945.570-8 - Reporting motor vehicle data.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Reporting motor vehicle... Reporting motor vehicle data. (a) Contractors conducting motor vehicle operations shall forward annually (on or before December 1) to the contracting officer their plan for acquisition of motor vehicles for...

  6. 48 CFR 945.570-8 - Reporting motor vehicle data.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Reporting motor vehicle... Reporting motor vehicle data. (a) Contractors conducting motor vehicle operations shall forward annually (on or before December 1) to the contracting officer their plan for acquisition of motor vehicles for...

  7. Delineating cooperative responses of processive motors in living cells.

    PubMed

    Efremov, Artem K; Radhakrishnan, Anand; Tsao, David S; Bookwalter, Carol S; Trybus, Kathleen M; Diehl, Michael R

    2014-01-21

    Characterizing the collective functions of cytoskeletal motors is critical to understanding mechanisms that regulate the internal organization of eukaryotic cells as well as the roles various transport defects play in human diseases. Though in vitro assays using synthetic motor complexes have generated important insights, dissecting collective motor functions within living cells still remains challenging. Here, we show that the protein heterodimerization switches FKBP-rapalog-FRB can be harnessed in engineered COS-7 cells to compare the collective responses of kinesin-1 and myosinVa motors to changes in motor number and cargo size. The dependence of cargo velocities, travel distances, and position noise on these parameters suggests that multiple myosinVa motors can cooperate more productively than collections of kinesins in COS-7 cells. In contrast to observations with kinesin-1 motors, the velocities and run lengths of peroxisomes driven by multiple myosinVa motors are found to increase with increasing motor density, but are relatively insensitive to the higher loads associated with transporting large peroxisomes in the viscoelastic environment of the COS-7 cell cytoplasm. Moreover, these distinctions appear to be derived from the different sensitivities of kinesin-1 and myosinVa velocities and detachment rates to forces at the single-motor level. The collective behaviors of certain processive motors, like myosinVa, may therefore be more readily tunable and have more substantial roles in intracellular transport regulatory mechanisms compared with those of other cytoskeletal motors.

  8. [Motor rehabilitation].

    PubMed

    Doménech, J; García-Aymerich, V; Juste, J; Ortiz, A

    2002-02-01

    The child's rehabilitation objectives are the same of the early intervention. The early intervention include motor approaches to facilitate the unique way of the newborn's expression: the movement and with it his holistic development. The motor approach is a classic aspect of early intervention but it is not itself early intervention. When the treatment objective is a term or preterm newborn or neonate the motor approach may be the principal method to facilitate perceptions experiences and basic habits. This intervention is not made with a specific physiotherapeutic technique. It is a sequential stimulation or development, without forget that the child must be taken as a whole. This point of view has special importance the first days of life and must be included in perinatal approach routines. In this paper we expose the work method of a Child Rehabilitation Team liked to a Newborn Unit.

  9. Optical Pickup Feeding Velocity Profile Design of Optical Disk Storage

    NASA Astrophysics Data System (ADS)

    Park, Juhn Ho; Seo, Heui-Sik; Lee, Jung Joon; Min, Byunghoon; Son, Heuigi

    2001-03-01

    Residual vibrations and jerks of a pickup body caused by the flexibility of an optical pickup feeding system in optical disk storage may degrade the quality of reading and writing, and increase the track access time. In this study, a feeding velocity profile that suppresses the residual vibrations and jerks is calculated and applied to a stepping-motor-driven feeding system. The calculated feeding velocity profile shows good results compared to the conventional feeding velocity profile of trapezoidal shape.

  10. Motor-operated gearbox efficiency

    SciTech Connect

    DeWall, K.G.; Watkins, J.C.; Bramwell, D.; Weidenhamer, G.H.

    1996-12-01

    Researchers at the Idaho National Engineering Laboratory recently conducted tests investigating the operating efficiency of the power train (gearbox) in motor-operators typically used in nuclear power plants to power motor-operated valves. Actual efficiency ratios were determined from in-line measurements of electric motor torque (input to the operator gearbox) and valve stem torque (output from the gearbox) while the operators were subjected to gradually increasing loads until the electric motor stalled. The testing included parametric studies under reduced voltage and elevated temperature conditions. As part of the analysis of the results, the authors compared efficiency values determined from testing to the values published by the operator manufacturer and typically used by the industry in calculations for estimating motor-operator capabilities. The operators they tested under load ran at efficiencies lower than the running efficiency (typically 50%) published by the operator manufacturer.

  11. Failure analysis of solid rocket apogee motors

    NASA Technical Reports Server (NTRS)

    Martin, P. J.

    1972-01-01

    The analysis followed five selected motors through initial design, development, test, qualification, manufacture, and final flight reports. An audit was conducted at the manufacturing plants to complement the literature search with firsthand observations of the current philosophies and practices that affect reliability of the motors. A second literature search emphasized acquisition of spacecraft and satellite data bearing on solid motor reliability. It was concluded that present practices at the plants yield highly reliable flight hardware. Reliability can be further improved by new developments of aft-end bonding and initiator/igniter nondestructive test methods, a safe/arm device, and an insulation formulation. Minimum diagnostic instrumentation is recommended for all motor flights. Surplus motors should be used in margin testing. Criteria should be established for pressure and zone curing. The motor contractor should be represented at launch. New design analyses should be made of stretched motors and spacecraft/motor pairs.

  12. CAG repeat size correlates to electrophysiological motor and sensory phenotypes in SBMA.

    PubMed

    Suzuki, Keisuke; Katsuno, Masahisa; Banno, Haruhiko; Takeuchi, Yu; Atsuta, Naoki; Ito, Mizuki; Watanabe, Hirohisa; Yamashita, Fumitada; Hori, Norio; Nakamura, Tomohiko; Hirayama, Masaaki; Tanaka, Fumiaki; Sobue, Gen

    2008-01-01

    Spinal and bulbar muscular atrophy (SBMA) is an adult-onset, lower motor neuron disease caused by an aberrant elongation of a CAG repeat in the androgen receptor (AR) gene. The main symptoms are weakness and atrophy of bulbar, facial and limb muscles, but sensory disturbances are frequently found in SBMA patients. Motor symptoms have been attributed to the accumulation of mutant AR in the nucleus of lower motor neurons, which is more profound in patients with a longer CAG repeat. We examined nerve conduction properties including F-waves in a total of 106 patients with genetically confirmed SBMA (mean age at data collection = 53.8 years; range = 31-75 years) and 85 control subjects. Motor conduction velocities (MCV), compound muscle action potentials (CMAP), sensory conduction velocities (SCV) and sensory nerve action potentials (SNAP) were significantly decreased in all nerves examined in the SBMA patients compared with that in the normal controls, indicating that axonal degeneration is the primary process in both motor and sensory nerves. More profound abnormalities were observed in the nerves of the upper limbs than in those of the lower limbs. F-waves in the median nerve were absent in 30 of 106 cases (28.3%), but no cases of absent F-waves were observed in the tibial nerve. From an analysis of the relationship between CMAPs and SNAPs, patients were identified with different electrophysiological phenotypes: motor-dominant, sensory-dominant and non-dominant phenotypes. The CAG repeat size and the age at onset were significantly different among the patients with motor- and sensory-dominant phenotypes, indicating that a longer CAG repeat is more closely linked to the motor-dominant phenotype and a shorter CAG repeat is more closely linked to the sensory-dominant phenotype. Furthermore, when we classified the patients by CAG repeat size, CMAP values showed a tendency to be decreased in patients with a longer CAG repeat (> or =47), while SNAPs were significantly

  13. Therma motor

    DOEpatents

    Kandarian, R.

    The disclosure is directed to a thermal motor utilizing two tapered prestressed parallel adjacent cylinders lengthwise disposed about one third in a coolant. Heat is applied to contacting portions of the cylinders outside the coolant to cause them to deform and turn. Heat sources such as industrial waste heat, geothermal hot water, solar radiation, etc. can be used.

  14. Motor Controllers

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Kollmorgen Corporation's Mermaid II two person submersible is propeller-driven by a system of five DC brushless motors with new electronic controllers that originated in work performed in a NASA/DOE project managed by Lewis Research Center. A key feature of the system is electric commutation rather than mechanical commutation for converting AC current to DC.

  15. High efficiency motor rewind study

    NASA Astrophysics Data System (ADS)

    Wallace, A. K.; Spee, R.

    1991-02-01

    The objective of performing this work was to evaluate a new technology used for rewinding electric motors. Motor performance evaluation was conducted at the motor test facility at Oregon State University. The test program consisted of comparing new high efficiency motor technology and standard rewind technology with the Unity-Plus system. The Unity-Plus configuration exhibited reduced efficiency over the complete load range compared to the other motors. Appropriately sized capacitors connected to the terminals of the conventional induction motor produced the same power factor improvement as the Unity-Plus system. Torque production and torque pulsation were very similar for all systems. The Unity-Plus configuration drew lower starting currents but the duration of the starting transient was increased. Motor temperature rise was about the same for all systems. Noise levels were about the same in all systems. Although determination of time to failure was not undertaken, the expected lifetime of the Unit-Plus system is probably less due to higher capacitor stress and higher insulation stress. The investigation concludes that a conventional induction motor with terminal capacitors is the most acceptable way of obtaining good efficiency and power factor and the Unity-Plus system cannot be recommended on the basis of any of the evaluation criteria used in this study.

  16. Ignition transient calculations in the Space Shuttle solid rocket motor

    NASA Astrophysics Data System (ADS)

    Jenkins, Rhonald M.; Foster, Winfred A., Jr.

    1993-07-01

    The work presented is part of an effort to develop a multidimensional ignition transient model for large solid propellant rocket motors. On the Space Shuttle, the ignition transient in the slot is induced when the igniter, itself a small rocket motor, is fired into the head-end portion of the main rocket motor. The computational results presented in this paper consider two different igniter configurations. The first configuration is a simulated Space Shuttle RSRM igniter which has one central nozzle that is parallel to the centerline of the motor. The second igniter configuration has a nozzle which is canted at an angle of 45 deg from the centerline of the motor. This paper presents a computational fluid dynamic (CFD) analyses of certain flow field characteristics inside the solid propellant star grain slot of the Space Shuttle during the ignition transient period of operation for each igniter configuration. The majority of studies made to date regarding ignition transient performance in solid rocket motors have concluded that the key parameter to be determined is the heat transfer rate to the propellant surface and hence the heat transfer coefficient between the gas and the propellant. In this paper the heat transfer coefficients, pressure and velocity distributions are calculated in the star slot. In order to validate the computational method and to attempt to establish a correlation between the flow field characteristics and the heat transfer rates a series of cold flow experimental investigations were conducted. The results of these experiments show excellent qualitative and quantitative agreement with the pressure and velocity distributions obtained from the CFD analysis. The CFD analysis utilized a classical pipe flow type correlation for the heat transfer rates. The experimental results provide an excellent qualitative comparison with regard to spatial distribution of the heat transfer rates as a function of nozzle configuration and igniter pressure. The

  17. Reduced evoked motor and sensory potential amplitudes in obstructive sleep apnea patients.

    PubMed

    Mihalj, Mario; Lušić, Linda; Đogaš, Zoran

    2016-06-01

    It is unknown to what extent chronic intermittent hypoxaemia in obstructive sleep apnea causes damage to the motor and sensory peripheral nerves. It was hypothesized that patients with obstructive sleep apnea would have bilaterally significantly impaired amplitudes of both motor and sensory peripheral nerve-evoked potentials of both lower and upper limbs. An observational study was conducted on 43 patients with obstructive sleep apnea confirmed by the whole-night polysomnography, and 40 controls to assess the relationship between obstructive sleep apnea and peripheral neuropathy. All obstructive sleep apnea subjects underwent standardized electroneurographic testing, with full assessment of amplitudes of evoked compound muscle action potentials, sensory neural action potentials, motor and sensory nerve conduction velocities, and distal motor and sensory latencies of the median, ulnar, peroneal and sural nerves, bilaterally. All nerve measurements were compared with reference values, as well as between the untreated patients with obstructive sleep apnea and control subjects. Averaged compound muscle action potential and sensory nerve action potential amplitudes were significantly reduced in the nerves of both upper and lower limbs in patients with obstructive sleep apnea compared with controls (P < 0.001). These results confirmed that patients with obstructive sleep apnea had significantly lower amplitudes of evoked action potentials of both motor and sensory peripheral nerves. Clinical/subclinical axonal damage exists in patients with obstructive sleep apnea to a greater extent than previously thought.

  18. Sliding of microtubules by a team of dynein motors: Understanding the effect of spatial distribution of motor tails and mutual exclusion of motor heads on microtubules

    NASA Astrophysics Data System (ADS)

    Singh, Hanumant Pratap; Takshak, Anjneya; Mall, Utkarsh; Kunwar, Ambarish

    2016-06-01

    Molecular motors are natural nanomachines that use the free energy released from ATP hydrolysis to generate mechanical forces. Cytoplasmic dynein motors often work collectively as a team to drive important processes such as axonal growth, proplatelet formation and mitosis, as forces generated by single motors are insufficient. A large team of dynein motors is used to slide cytoskeletal microtubules with respect to one another during the process of proplatelet formation and axonal growth. These motors attach to a cargo microtubule via their tail domains, undergo the process of detachment and reattachment of their head domains on another track microtubule, while sliding the cargo microtubule along the track. Traditional continuum/mean-field approaches used in the past are not ideal for studying the sliding mechanism of microtubules, as they ignore spatial and temporal fluctuations due to different possible distributions of motor tails on cargo filament, as well as binding/unbinding of motors from their track. Therefore, these models cannot be used to address important questions such as how the distribution of motor tails on microtubules, or how the mutual exclusion of motor heads on microtubule tracks affects the sliding velocity of cargo microtubule. To answer these, here we use a computational stochastic model where we model each dynein motor explicitly. In our model, we use both random as well as uniform distributions of dynein motors on cargo microtubule, as well as mutual exclusion of motors on microtubule tracks. We find that sliding velocities are least affected by the distribution of motor tails on microtubules, whereas they are greatly affected by mutual exclusion of motor heads on microtubule tracks. We also find that sliding velocity depends on the length of cargo microtubule if mutual exclusion among motor heads is considered.

  19. Geostatistical Modeling of Pore Velocity

    SciTech Connect

    Devary, J.L.; Doctor, P.G.

    1981-06-01

    A significant part of evaluating a geologic formation as a nuclear waste repository involves the modeling of contaminant transport in the surrounding media in the event the repository is breached. The commonly used contaminant transport models are deterministic. However, the spatial variability of hydrologic field parameters introduces uncertainties into contaminant transport predictions. This paper discusses the application of geostatistical techniques to the modeling of spatially varying hydrologic field parameters required as input to contaminant transport analyses. Kriging estimation techniques were applied to Hanford Reservation field data to calculate hydraulic conductivity and the ground-water potential gradients. These quantities were statistically combined to estimate the groundwater pore velocity and to characterize the pore velocity estimation error. Combining geostatistical modeling techniques with product error propagation techniques results in an effective stochastic characterization of groundwater pore velocity, a hydrologic parameter required for contaminant transport analyses.

  20. Analysis of Tiny Piezoelectric Ultrasonic Linear Motor

    NASA Astrophysics Data System (ADS)

    Ko, Hyun‑Phill; Lee, Kyong‑Jae; Yoo, Kyoung‑Ho; Kang, Chong‑Yun; Kim, Sangsig; Yoon, Seok‑Jin

    2006-05-01

    A modified structure for tiny ultrasonic linear motors has been developed, and various shaft materials have been tested in order to improve dynamic properties. The shaft material has a direct influence on efficiency, reliability, and quality of the motors and their dynamic properties. The shaft material is crucial to achieve high performance. Shafts of with various materials, such as a stainless steel, stainless steel coated with diamond like carbon (DLC), a Pyrex, and a graphite, can make it possible to improve dynamic properties of the motors over a wide range of tribological conditions. For the motor with a stainless steel shaft coated with DLC at 47 kHz, its velocity is 6.5 mm/s and its force is 110 mN. When the motor has a Pyrex shaft, a force of 140 mN is reached at 52 kHz. Accordingly, the maximum force produced by a motor with a graphite shaft is estimated as 97 mN. The velocity of this motor was 15 mm/s. We found that graphite has a fine surface and a directional texture which can help a moving element achieve linear motion. Finally, the use of a cap resulted in significantly improving stable operation. A motor with a graphite or a Pyrex shaft showed very stable operation and improved dynamic characteristics.

  1. Three-dimensional velocity measurements using LDA

    NASA Astrophysics Data System (ADS)

    Buchhave, Preben

    The design requirements for and development of an LDA that measures the three components of the fluid velocity vector are described. The problems encountered in LDA measurements in highly turbulent flows, multivariate response, velocity bias, spatial resolution, temporal resolution, and dynamic range, are discussed. The use of the fringe and/or the reference beam methods to measure the three velocity components, and the use of color, frequency shift, and polarization to separate three velocity projections are examined. Consideration is given to the coordinate transformation, the presentation of three-dimensional LDA data, and the possibility of three-dimensional bias correction. Procedures for conducting three-dimensional LDA measurements are proposed.

  2. Dry deposition velocities

    SciTech Connect

    Sehmel, G.A.

    1984-03-01

    Dry deposition velocities are very difficult to predict accurately. In this article, reported values of dry deposition velocities are summarized. This summary includes values from the literature on field measurements of gas and particle dry deposition velocities, and the uncertainties inherent in extrapolating field results to predict dry deposition velocities are discussed. A new method is described for predicting dry deposition velocity using a least-squares correlation of surface mass transfer resistances evaluated in wind tunnel experiments. 14 references, 4 figures, 1 table.

  3. Solar-wind velocity decreases

    NASA Astrophysics Data System (ADS)

    Geranios, A.

    1980-08-01

    A model is developed to account for the solar wind electron and proton temperature decreases observed following the passage of an interplanetary shock wave and during the velocity decrease of a solar wind stream. The equations of mass and energy conservation are solved for a fully ionized, electrically neutral plasma expanding radially and spherically symmetrically, taking into account the heat flux from the solor corona to the plasma along the open magnetic field lines, and the electron thermal conductivity. An analytical relationship between the temperature and the velocity of the solar wind plasma is obtained which is found to be in agreement with experimental measurements made by the Vela 5 and 6 and IMP 6 satellites from August 1969-May 1974. It is thus proposed that the observed low plasma temperatures are due to the fact that the temperature decrease of the expanding plasma exceeds the heat gain due to thermal conduction from the corona.

  4. Is distal motor and/or sensory demyelination a distinctive feature of anti-MAG neuropathy?

    PubMed

    Lozeron, Pierre; Ribrag, Vincent; Adams, David; Brisset, Marion; Vignon, Marguerite; Baron, Marine; Malphettes, Marion; Theaudin, Marie; Arnulf, Bertrand; Kubis, Nathalie

    2016-09-01

    To report the frequency of the different patterns of sensory and motor electrophysiological demyelination distribution in patients with anti-MAG neuropathy in comparison with patients with IgM neuropathy without MAG reactivity (IgM-NP). Thirty-five anti-MAG patients at early disease stage (20.1 months) were compared to 23 patients with IgM-NP; 21 CIDP patients and 13 patients with CMT1a neuropathy were used as gold standard neuropathies with multifocal and homogeneous demyelination, respectively. In all groups, standard motor and sensory electrophysiological parameters, terminal latency index and modified F ratio were investigated. Motor electrophysiological demyelination was divided in four profiles: distal, homogeneous, proximal, and proximo-distal. Distal sensory and sensorimotor demyelination were evaluated. Anti-MAG neuropathy is a demyelinating neuropathy in 91 % of cases. In the upper limbs, reduced TLI is more frequent in anti-MAG neuropathy, compared to IgM-NP. But, predominant distal demyelination of the median nerve is encountered in only 43 % of anti-MAG neuropathy and is also common in IgM-NP (35 %). Homogeneous demyelination was the second most frequent pattern (31 %). Concordance of electrophysiological profiles across motor nerves trunks is low and median nerve is the main site of distal motor conduction slowing. Reduced sensory conduction velocities occurs in 14 % of patients without evidence of predominant distal slowing. Simultaneous sensory and motor distal slowing was more common in the median nerve of anti-MAG neuropathy than IgM-NP. Electrophysiological distal motor demyelination and sensory demyelination are not a distinctive feature of anti-MAG reactivity. In anti-MAG neuropathy it is mainly found in the median nerve suggesting a frequent nerve compression at wrist.

  5. Comparison of the fastest regenerating motor and sensory myelinated axons in the same peripheral nerve.

    PubMed

    Moldovan, Mihai; Sørensen, Jesper; Krarup, Christian

    2006-09-01

    Functional outcome after peripheral nerve regeneration is often poor, particularly involving nerve injuries far from their targets. Comparison of sensory and motor axon regeneration before target reinnervation is not possible in the clinical setting, and previous experimental studies addressing the question of differences in growth rates of different nerve fibre populations led to conflicting results. We developed an animal model to compare growth and maturation of the fastest growing sensory and motor fibres within the same mixed nerve after Wallerian degeneration. Regeneration of cat tibial nerve after crush (n = 13) and section (n = 7) was monitored for up to 140 days, using implanted cuff electrodes placed around the sciatic and tibial nerves and wire electrodes at plantar muscles. To distinguish between sensory and motor fibres, recordings were carried out from L6-S2 spinal roots using cuff electrodes. The timing of laminectomy was based on the presence of regenerating fibres along the nerve within the tibial cuff. Stimulation of unlesioned tibial nerves (n = 6) evoked the largest motor response in S1 ventral root and the largest sensory response in L7 dorsal root. Growth rates were compared by mapping the regenerating nerve fibres within the tibial nerve cuff to all ventral or dorsal roots and, regardless of the lesion type, the fastest growth was similar in sensory and motor fibres. Maturation was assessed as recovery of the maximum motor and sensory conduction velocities (CVs) within the tibial nerve cuff. Throughout the observation period the CV was approximately 14% faster in regenerated sensory fibres than in motor fibres in accordance with the difference observed in control nerves. Recovery of amplitude was only partial after section, whereas the root distribution pattern was restored. Our data suggest that the fastest growth and maturation rates that can be achieved during regeneration are similar for motor and sensory myelinated fibres.

  6. Note: A helical velocity selector for continuous molecular beams.

    PubMed

    Szewc, Carola; Collier, James D; Ulbricht, Hendrik

    2010-10-01

    We report on a modern realization of the classic helical velocity selector for gas phase particle beams. The device operates stably under high vacuum conditions at rotational frequencies limited only by commercial dc motor capabilities. Tuning the rotational frequency allows selective scanning over a broad velocity band. The width of the selected velocity distributions at full-width-half-maximum is as narrow as a few percent of the selected mean velocity and independent of the rotational speed of the selector. The selector generates low vibrational noise amplitudes comparable to mechanically damped state-of-the-art turbo-molecular pumps and is therefore compatible with vibration sensitive experiments like molecule interferometry.

  7. Note: A helical velocity selector for continuous molecular beams

    NASA Astrophysics Data System (ADS)

    Szewc, Carola; Collier, James D.; Ulbricht, Hendrik

    2010-10-01

    We report on a modern realization of the classic helical velocity selector for gas phase particle beams. The device operates stably under high vacuum conditions at rotational frequencies limited only by commercial dc motor capabilities. Tuning the rotational frequency allows selective scanning over a broad velocity band. The width of the selected velocity distributions at full-width-half-maximum is as narrow as a few percent of the selected mean velocity and independent of the rotational speed of the selector. The selector generates low vibrational noise amplitudes comparable to mechanically damped state-of-the-art turbo-molecular pumps and is therefore compatible with vibration sensitive experiments like molecule interferometry.

  8. Fiber Optic Velocity Interferometry

    SciTech Connect

    Neyer, Barry T.

    1988-04-01

    This paper explores the use of a new velocity measurement technique that has several advantages over existing techniques. It uses an optical fiber to carry coherent light to and from a moving target. A Fabry-Perot interferometer, formed by a gradient index lens and the moving target, produces fringes with a frequency proportional to the target velocity. This technique can measure velocities up to 10 km/s, is accurate, portable, and completely noninvasive.

  9. Angular velocity discrimination

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary K.

    1990-01-01

    Three experiments designed to investigate the ability of naive observers to discriminate rotational velocities of two simultaneously viewed objects are described. Rotations are constrained to occur about the x and y axes, resulting in linear two-dimensional image trajectories. The results indicate that observers can discriminate angular velocities with a competence near that for linear velocities. However, perceived angular rate is influenced by structural aspects of the stimuli.

  10. Molecular motors: thermodynamics and the random walk.

    PubMed Central

    Thomas, N.; Imafuku, Y.; Tawada, K.

    2001-01-01

    The biochemical cycle of a molecular motor provides the essential link between its thermodynamics and kinetics. The thermodynamics of the cycle determine the motor's ability to perform mechanical work, whilst the kinetics of the cycle govern its stochastic behaviour. We concentrate here on tightly coupled, processive molecular motors, such as kinesin and myosin V, which hydrolyse one molecule of ATP per forward step. Thermodynamics require that, when such a motor pulls against a constant load f, the ratio of the forward and backward products of the rate constants for its cycle is exp [-(DeltaG + u(0)f)/kT], where -DeltaG is the free energy available from ATP hydrolysis and u(0) is the motor's step size. A hypothetical one-state motor can therefore act as a chemically driven ratchet executing a biased random walk. Treating this random walk as a diffusion problem, we calculate the forward velocity v and the diffusion coefficient D and we find that its randomness parameter r is determined solely by thermodynamics. However, real molecular motors pass through several states at each attachment site. They satisfy a modified diffusion equation that follows directly from the rate equations for the biochemical cycle and their effective diffusion coefficient is reduced to D-v(2)tau, where tau is the time-constant for the motor to reach the steady state. Hence, the randomness of multistate motors is reduced compared with the one-state case and can be used for determining tau. Our analysis therefore demonstrates the intimate relationship between the biochemical cycle, the force-velocity relation and the random motion of molecular motors. PMID:11600075

  11. A general two-cycle network model of molecular motors

    NASA Astrophysics Data System (ADS)

    Zhang, Yunxin

    2009-09-01

    Molecular motors are single macromolecules that generate forces at the piconewton range and nanometer scale. They convert chemical energy into mechanical work by moving along filamentous structures. In this paper, we study the velocity of two-head molecular motors in the framework of a mechanochemical network theory. The network model, a generalization of the recently work of Liepelt and Lipowsky [Steffen Liepelt, Reinhard Lipowsky, Kinesins network of chemomechanical motor cycles, Physical Review Letters 98 (25) (2007) 258102], is based on the discrete mechanochemical states of a molecular motor with multiple cycles. By generalizing the mathematical method developed by Fisher and Kolomeisky for a single cycle motor [Michael E. Fisher, Anatoly B. Kolomeisky, Simple mechanochemistry describes the dynamics of kinesin molecules, Proceedings of the National Academy of Sciences 98 (14) (2001) 7748-7753], we are able to obtain an explicit formula for the velocity of a molecular motor.

  12. A Preliminary Investigation on the Destruction of Solid-Propellant Rocket Motors by Impact from Small Particles

    NASA Technical Reports Server (NTRS)

    Carter, David J., Jr.

    1960-01-01

    An investigation was conducted to determine whether solid-propellant rocket motors could be ignited and destroyed by small-particle impacts at particle velocities up to a approximately 10,940 feet per second. Spheres ranging from 1/16 to 7/32 inch in diameter were fired into simulated rocket motors containing T-22 propellant over a range of ambient pressures from sea level to 0.12 inch of mercury absolute. Simulated cases of stainless steel, aluminum alloy, and laminated Fiberglas varied in thickness from 1/50 to 1/8 inch. Within the scope of this investigation, it was found that ignition and explosive destruction of simulated steel-case rocket motors could result from impacts by steel spheres at the lowest attainable pressure.

  13. Electronic cam motion generation with special reference to constrained velocity, acceleration, and jerk.

    PubMed

    Liao, Chung-Shu; Jeng, Shyr-Long; Chieng, Wei-Hua

    2004-07-01

    Electronic cam motion involves velocity tracking control of the master motor and trajectory generation of the slave motor. Special concerns such as the limits of the velocity, acceleration, and jerk are beyond the considerations in the conventional electronic cam motion control. This study proposes the curve-fitting of a Lagrange polynomial to the cam profile, based on trajectory optimization by cubic B-spline interpolation. The proposed algorithms may yield a higher tracking precision than the conventional master-slaves control method does, providing an optimization problem is concerned. The optimization problem contains three dynamic constraints including velocity, acceleration, and jerk of the motor system.

  14. Passive system with tunable group velocity for propagating electrical pulses from sub- to superluminal velocities.

    PubMed

    Haché, Alain; Essiambre, Sophie

    2004-05-01

    We report an observation of tunable group velocity from sub-luminal to superluminal in a completely passive system. Electric pulses are sent along a spatially periodic conducting medium containing a punctual nonlinearity, and the resulting amplitude-dependent phase shift allows us to control dispersion and the propagation velocity at the stop band frequency.

  15. Indicators: Conductivity

    EPA Pesticide Factsheets

    Conductivity is a measure of the ability of water to pass an electrical current. Because dissolved salts and other inorganic chemicals conduct electrical current, conductivity increases as salinity increases.

  16. Gross motor control

    MedlinePlus

    Gross motor control is the ability to make large, general movements (such as waving an arm or lifting a ... Gross motor control is a milestone in the development of an infant. Infants develop gross motor control before they ...

  17. Starting motor

    SciTech Connect

    Tanaka, T.; Hamano, I

    1989-05-23

    This patent describes a starting motor having a housing, planetary reduction gears including an internal gear in the housing. The improvement consists of an elastic member having a first annular portion mounted in engagement with a fixed annular member of the housing and a plurality of protruding axially extending elastic portions providing a corrugated surface pressed into engagement with an end portion of the internal gear, the elastic member being sandwiched between the internal gear and the housing member, the protruding axially extending elastic portions providing resilient means which flex and incline circumferentially under turning force from the internal gear and exert reactive thrust on the internal gear elastically so that the frictional force at the abutting surfaces of the protruding portions holds the internal gear in resilient engagement with the elastic member and the resilient means acts as a buffer to absorb rotary impact force developing in the planetary reduction gears.

  18. Optimisation of the mean boat velocity in rowing.

    PubMed

    Rauter, G; Baumgartner, L; Denoth, J; Riener, R; Wolf, P

    2012-01-01

    In rowing, motor learning may be facilitated by augmented feedback that displays the ratio between actual mean boat velocity and maximal achievable mean boat velocity. To provide this ratio, the aim of this work was to develop and evaluate an algorithm calculating an individual maximal mean boat velocity. The algorithm optimised the horizontal oar movement under constraints such as the individual range of the horizontal oar displacement, individual timing of catch and release and an individual power-angle relation. Immersion and turning of the oar were simplified, and the seat movement of a professional rower was implemented. The feasibility of the algorithm, and of the associated ratio between actual boat velocity and optimised boat velocity, was confirmed by a study on four subjects: as expected, advanced rowing skills resulted in higher ratios, and the maximal mean boat velocity depended on the range of the horizontal oar displacement.

  19. Reliable Diameter Control of Carbon Nanotube Nanobundles Using Withdrawal Velocity.

    PubMed

    Shin, Jung Hwal; Kim, Kanghyun; An, Taechang; Choi, WooSeok; Lim, Geunbae

    2016-12-01

    Carbon nanotube (CNT) nanobundles are widely used in nanoscale imaging, fabrication, and electrochemical and biological sensing. The diameter of CNT nanobundles should be controlled precisely, because it is an important factor in determining electrode performance. Here, we fabricated CNT nanobundles on tungsten tips using dielectrophoresis (DEP) force and controlled their diameters by varying the withdrawal velocity of the tungsten tips. Withdrawal velocity pulling away from the liquid-air interface could be an important, reliable parameter to control the diameter of CNT nanobundles. The withdrawal velocity was controlled automatically and precisely with a one-dimensional motorized stage. The effect of the withdrawal velocity on the diameter of CNT nanobundles was analyzed theoretically and compared with the experimental results. Based on the attachment efficiency, the withdrawal velocity is inversely proportional to the diameter of the CNT nanobundles; this has been demonstrated experimentally. Control of the withdrawal velocity will play an important role in fabricating CNT nanobundles using DEP phenomena.

  20. Diffusive Promotion by Velocity Gradient of Cytoplasmic Streaming (CPS) in Nitella Internodal Cells

    PubMed Central

    Kikuchi, Kenji; Mochizuki, Osamu

    2015-01-01

    Cytoplasmic streaming (CPS) is well known to assist the movement of nutrients, organelles and genetic material by transporting all of the cytoplasmic contents of a cell. CPS is generated by motility organelles that are driven by motor proteins near a membrane surface, where the CPS has been found to have a flat velocity profile in the flow field according to the sliding theory. There is a consistent mixing of contents inside the cell by CPS if the velocity gradient profile is flattened, which is not assisted by advection diffusion but is only supported by Brownian diffusion. Although the precise flow structure of the cytoplasm has an important role for cellular metabolism, the hydrodynamic mechanism of its convection has not been clarified. We conducted an experiment to visualise the flow of cytoplasm in Nitella cells by injecting tracer fluorescent nanoparticles and using a flow visualisation system in order to understand how the flow profile affects their metabolic system. We determined that the velocity field in the cytosol has an obvious velocity gradient, not a flattened gradient, which suggests that the gradient assists cytosolic mixing by Taylor–Aris dispersion more than by Brownian diffusion. PMID:26694322

  1. Diffusive Promotion by Velocity Gradient of Cytoplasmic Streaming (CPS) in Nitella Internodal Cells.

    PubMed

    Kikuchi, Kenji; Mochizuki, Osamu

    2015-01-01

    Cytoplasmic streaming (CPS) is well known to assist the movement of nutrients, organelles and genetic material by transporting all of the cytoplasmic contents of a cell. CPS is generated by motility organelles that are driven by motor proteins near a membrane surface, where the CPS has been found to have a flat velocity profile in the flow field according to the sliding theory. There is a consistent mixing of contents inside the cell by CPS if the velocity gradient profile is flattened, which is not assisted by advection diffusion but is only supported by Brownian diffusion. Although the precise flow structure of the cytoplasm has an important role for cellular metabolism, the hydrodynamic mechanism of its convection has not been clarified. We conducted an experiment to visualise the flow of cytoplasm in Nitella cells by injecting tracer fluorescent nanoparticles and using a flow visualisation system in order to understand how the flow profile affects their metabolic system. We determined that the velocity field in the cytosol has an obvious velocity gradient, not a flattened gradient, which suggests that the gradient assists cytosolic mixing by Taylor-Aris dispersion more than by Brownian diffusion.

  2. Filament overwrapped motor case technology

    NASA Astrophysics Data System (ADS)

    Compton, Joel P.

    1993-11-01

    Atlantic Research Corporation (ARC) joined with the French Societe Europeenne de Propulsion (SEP) to develop and deliver to the U.S. Navy a small quantity of composite filament wound rocket motors to demonstrate a manufacturing technique that was being applied at the two companies. It was perceived that the manufacturing technique could produce motors that would be light in weight, inexpensive to produce, and that had a good chance of meeting insensitive munitions (IM) requirements that were being formulated by the Navy in the early 1980s. Under subcontract to ARC, SEP designed, tested, and delivered 2.75-inch rocket motors to the U.S. Navy for IM tests that were conducted in 1989 at China Lake, California. The program was one of the first to be founded by Nunn Amendment money. The Government-to-Government program was sponsored by the Naval Air Systems Command and was monitored by the Naval Surface Warfare Center, Indian Head (NSWC-IH), Maryland. The motor propellant that was employed was a new, extruded composite formulation that was under development at the Naval Surface Warfare Center. The following paper describes the highlights of the program and gives the results of structural and ballistic static tests and insensitive munitions tests that were conducted on demonstration motors.

  3. Motor control for a brushless DC motor

    NASA Technical Reports Server (NTRS)

    Peterson, William J. (Inventor); Faulkner, Dennis T. (Inventor)

    1985-01-01

    This invention relates to a motor control system for a brushless DC motor having an inverter responsively coupled to the motor control system and in power transmitting relationship to the motor. The motor control system includes a motor rotor speed detecting unit that provides a pulsed waveform signal proportional to rotor speed. This pulsed waveform signal is delivered to the inverter to thereby cause an inverter fundamental current waveform output to the motor to be switched at a rate proportional to said rotor speed. In addition, the fundamental current waveform is also pulse width modulated at a rate proportional to the rotor speed. A fundamental current waveform phase advance circuit is controllingly coupled to the inverter. The phase advance circuit is coupled to receive the pulsed waveform signal from the motor rotor speed detecting unit and phase advance the pulsed waveform signal as a predetermined function of motor speed to thereby cause the fundamental current waveform to be advanced and thereby compensate for fundamental current waveform lag due to motor winding reactance which allows the motor to operate at higher speeds than the motor is rated while providing optimal torque and therefore increased efficiency.

  4. High Velocity Gas Gun

    NASA Technical Reports Server (NTRS)

    1988-01-01

    A video tape related to orbital debris research is presented. The video tape covers the process of loading a High Velocity Gas Gun and firing it into a mounted metal plate. The process is then repeated in slow motion.

  5. Velocity of Sound

    ERIC Educational Resources Information Center

    Gillespie, A.

    1975-01-01

    Describes a method for the determination of the velocity of sound using a dual oscilloscope on which is displayed the sinusoidal input into a loudspeaker and the signal picked up by a microphone. (GS)

  6. Models of motor-assisted transport of intracellular particles.

    PubMed Central

    Smith, D A; Simmons, R M

    2001-01-01

    One-dimensional models are presented for the macroscopic intracellular transport of vesicles and organelles by molecular motors on a network of aligned intracellular filaments. A motor-coated vesicle or organelle is described as a diffusing particle binding intermittently to filaments, when it is transported at the motor velocity. Two models are treated in detail: 1) a unidirectional model, where only one kind of motor is operative and all filaments have the same polarity; and 2) a bidirectional model, in which filaments of both polarities exist (for example, a randomly polarized actin network for myosin motors) and/or particles have plus-end and minus-end motors operating on unipolar filaments (kinesin and dynein on microtubules). The unidirectional model provides net particle transport in the absence of a concentration gradient. A symmetric bidirectional model, with equal mixtures of filament polarities or plus-end and minus-end motors of the same characteristics, provides rapid transport down a concentration gradient and enhanced dispersion of particles from a point source by motor-assisted diffusion. Both models are studied in detail as a function of the diffusion constant and motor velocity of bound particles, and their rates of binding to and detachment from filaments. These models can form the basis of more realistic models for particle transport in axons, melanophores, and the dendritic arms of melanocytes, in which networks of actin filaments and microtubules coexist and motors for both types of filament are implicated. PMID:11159382

  7. Solvent-driven chemical motor

    NASA Astrophysics Data System (ADS)

    Mitsumata, Tetsu; Ikeda, Kazuo; Gong, Jian Ping; Osada, Yoshihito

    1998-10-01

    A solvent-driven chemical motor using amphiphilic polymer gel has been fabricated. The driving force of the gel originates from the surface tension of spreading organic fluid which is pumped out by osmotic and hydrostatic pressures in the gel. A tetrahydrofurane-swollen gel equipped with a spouting hole made a controlled translational motion with a velocity of 77 mm/s or rotational motion with a maximum speed of 400 rpm and a torque of 10-9-10-7 Nm on the water surface. A generator to produce an electric power with a maximum electromotive force of 15 mV and electric power of 0.2 μW has also been constructed. The successful fabrication of gel motor may produce a new era of soft machine systems which work without pollution and unnecessary intermediates.

  8. Wind motor

    SciTech Connect

    Biscomb, L. I.

    1985-07-09

    A spider-like carrier having at least three generally horizontal arms has a hub mounted to the vertical, rotary-axis input shaft of a load. Each arm has at least one horizontal cross-arm secured to it near its radially outer end, which is supported from the ground by a low-friction support device such as a wheel or set of wheels. Mounted on each arm at the cross-arm or cross-arms is at least one sail, vane, airfoil or similar working member which is erected or spread generally normally to the wind when the respective arm is located for the working member to be blown downwind and is feathered or headed to the wind when the respective arm is located for the working member to be driven upwind. Horizontal axis and vertical axis journalling options for the working members and various sail shapes are shown, including a concave/convex sail and motor-oriented airfoil shape which provides lift when being driven upwind are shown.

  9. Tetrodotoxic poisoning from ingestion of a porcupine fish (Diodon hystrix) in Papua New Guinea: nerve conduction studies.

    PubMed

    Trevett, A J; Mavo, B; Warrell, D A

    1997-01-01

    Near Port Moresby in Papua New Guinea, three of four adult family members who ate a porcupine fish (Diodon hystrix) were severely poisoned. Within one hour of the meal, both the mother and her older daughter had developed paraesthesiae, ataxia, hypersalivation, sweating, and had collapsed and died. The younger daughter developed similar symptoms with progressive paralysis requiring mechanical ventilation for 24 hr, but she made a complete recovery 10 days after the poisoning. In this patient, nerve conduction studies showed reduced sensory and motor conduction velocities and evoked amplitudes with gradual improvement in parallel with the patient's clinical condition, consistent with the known action of tetrodotoxin on voltage-gated sodium channels.

  10. Dual piezoelecttic actuators for the traveling wave ultrasonic linear motor

    NASA Astrophysics Data System (ADS)

    Suybangdum, P.; Smithmaitrie, P.; Laoratanakul, P.

    2009-12-01

    The effect of a dual piezoelectric actuators ultrasonic linear motor is studied in this research. The two piezoelectric actuators are bonded with a linear elastic stator. The stator generates the traveling wave when the actuators are subjected to the harmonic excitations. Vibration characteristics of the linear stator are determined by using the finite element analysis, i.e., modal, harmonic and transient responses. In the experiment, the motor characteristics are tested, i.e., the maximum velocity, operating frequency and applied voltage. In addition, the relationship between the pre-load and velocity of the motor is reported. The result shows that the maximum velocity of the motor occurs at a specific per-load. The comparison of the operating frequency and harmonic response shows well agreement between the finite element and experimental results.

  11. Dual piezoelecttic actuators for the traveling wave ultrasonic linear motor

    NASA Astrophysics Data System (ADS)

    Suybangdum, P.; Smithmaitrie, P.; Laoratanakul, P.

    2010-03-01

    The effect of a dual piezoelectric actuators ultrasonic linear motor is studied in this research. The two piezoelectric actuators are bonded with a linear elastic stator. The stator generates the traveling wave when the actuators are subjected to the harmonic excitations. Vibration characteristics of the linear stator are determined by using the finite element analysis, i.e., modal, harmonic and transient responses. In the experiment, the motor characteristics are tested, i.e., the maximum velocity, operating frequency and applied voltage. In addition, the relationship between the pre-load and velocity of the motor is reported. The result shows that the maximum velocity of the motor occurs at a specific per-load. The comparison of the operating frequency and harmonic response shows well agreement between the finite element and experimental results.

  12. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Allen, Philip B.

    1979-01-01

    Examines Drude's classical (1900) theory of electrical conduction, details the objections to and successes of the 1900 theory, and investigates the Quantum (1928) theory of conduction, reviewing its successes and limitations. (BT)

  13. INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Monte—Carlo Simulation of Multiple-Molecular-Motor Transport

    NASA Astrophysics Data System (ADS)

    Wang, Zi-Qing; Wang, Guo-Dong; Shen, Wei-Bo

    2010-10-01

    Multimotor transport is studied by Monte-Carlo simulation with consideration of motor detachment from the filament. Our work shows, in the case of low load, the velocity of multi-motor system can decrease or increase with increasing motor numbers depending on the single motor force-velocity curve. The stall force and run-length reduced greatly compared to other models. Especially in the case of low ATP concentrations, the stall force of multi motor transport even smaller than the single motor's stall force.

  14. Effect of low frequency transcutaneous magnetic stimulation on sensory and motor transmission.

    PubMed

    Leung, Albert; Shukla, Shivshil; Lee, Jacquelyn; Metzger-Smith, Valerie; He, Yifan; Chen, Jeffrey; Golshan, Shahrokh

    2015-09-01

    Peripheral nerve injury diminishes fast conducting large myelinated afferent fibers transmission but enhances smaller pain transmitting fibers firing. This aberrant afferent neuronal behavior contributes to development of chronic post-traumatic peripheral neuropathic pain (PTP-NP). Non-invasive dynamic magnetic flux stimulation has been implicated in treating PTP-NP, a condition currently not adequately addressed by other therapies including transcutaneous electrical nerve stimulation (TENS). The current study assessed the effect of low frequency transcutaneous magnetic stimulation (LFTMS) on peripheral sensory thresholds, nerve conduction properties, and TENS induced fast afferent slowing effect as measured by motor and sensory conduction studies in the ulnar nerve. Results indicated sham LFTMS with TENS (Sham + TENS) significantly (P = 0.02 and 0.007, respectively) reduces sensory conduction velocity (CV) and increases sensory onset latency (OL), and motor peak latency (PL) whereas, real LFTMS with TENS (Real + TENS) reverses effects of TENS on sensory CV and OL, and significantly (P = 0.036) increases the sensory PL. LFTMS alone significantly (P < 0.05) elevates sensory PL and onset-to-peak latency. LFTMS appears to reverse TENS slowing effect on fast conducting fibers and casts a selective peripheral modulatory effect on slow conducting pain afferent fibers.

  15. Velocity Based Modulus Calculations

    NASA Astrophysics Data System (ADS)

    Dickson, W. C.

    2007-12-01

    A new set of equations are derived for the modulus of elasticity E and the bulk modulus K which are dependent only upon the seismic wave propagation velocities Vp, Vs and the density ρ. The three elastic moduli, E (Young's modulus), the shear modulus μ (Lamé's second parameter) and the bulk modulus K are found to be simple functions of the density and wave propagation velocities within the material. The shear and elastic moduli are found to equal the density of the material multiplied by the square of their respective wave propagation-velocities. The bulk modulus may be calculated from the elastic modulus using Poisson's ratio. These equations and resultant values are consistent with published literature and values in both magnitude and dimension (N/m2) and are applicable to the solid, liquid and gaseous phases. A 3D modulus of elasticity model for the Parkfield segment of the San Andreas Fault is presented using data from the wavespeed model of Thurber et al. [2006]. A sharp modulus gradient is observed across the fault at seismic depths, confirming that "variation in material properties play a key role in fault segmentation and deformation style" [Eberhart-Phillips et al., 1993] [EPM93]. The three elastic moduli E, μ and K may now be calculated directly from seismic pressure and shear wave propagation velocities. These velocities may be determined using conventional seismic reflection, refraction or transmission data and techniques. These velocities may be used in turn to estimate the density. This allows velocity based modulus calculations to be used as a tool for geophysical analysis, modeling, engineering and prospecting.

  16. Results of a 24-inch Hybrid Motor Performance Uncertainty Analysis

    NASA Technical Reports Server (NTRS)

    Sims, Joseph D.; Coleman, Hugh W.

    1998-01-01

    The subscale (11 and 24-inch) hybrid motors at the Marshall Space Flight Center (MSFC) have been used as versatile and cost effective testbeds for developing new technology. Comparisons between motor configuration, ignition systems, feed systems, fuel formulations, and nozzle materials have been carried out without detailed consideration as to haw "good" the motor performance data were. For the 250,000 lb/thrust motor developed by the Hybrid Propulsion Demonstration Program consortium, this shortcoming is particularly risky because motor performance will likely be used as put of a set of downselect criteria to choose between competing ignition and feed systems under development. This analysis directly addresses that shortcoming by applying uncertainty analysis techniques to the experimental determination of the characteristic velocity, theoretical characteristic velocity, and characteristic velocity efficiency for a 24-inch motor firing. With the adoption of fuel-lined headends, flow restriction, and aft mixing chambers, state of the an 24-inch hybrid motors have become very efficient However, impossibly high combustion efficiencies (some computed as high as 108%) have been measured in some tests with 11-inch motors. This analysis has given new insight into explaining how these efficiencies were measured to be so high, and into which experimental measurements contribute the most to the overall uncertainty.

  17. Mean velocity and moments of turbulent velocity fluctuations in the wake of a model ship propulsor

    NASA Astrophysics Data System (ADS)

    Pêgo, J. P.; Lienhart, H.; Durst, F.

    2007-08-01

    Pod drives are modern outboard ship propulsion systems with a motor encapsulated in a watertight pod, whose shaft is connected directly to one or two propellers. The whole unit hangs from the stern of the ship and rotates azimuthally, thus providing thrust and steering without the need of a rudder. Force/momentum and phase-resolved laser Doppler anemometry (LDA) measurements were performed for in line co-rotating and contra-rotating propellers pod drive models. The measurements permitted to characterize these ship propulsion systems in terms of their hydrodynamic characteristics. The torque delivered to the propellers and the thrust of the system were measured for different operation conditions of the propellers. These measurements lead to the hydrodynamic optimization of the ship propulsion system. The parameters under focus revealed the influence of distance between propeller planes, propeller frequency of rotation ratio and type of propellers (co- or contra-rotating) on the overall efficiency of the system. Two of the ship propulsion systems under consideration were chosen, based on their hydrodynamic characteristics, for a detailed study of the swirling wake flow by means of laser Doppler anemometry. A two-component laser Doppler system was employed for the velocity measurements. A light barrier mounted on the axle of the rear propeller motor supplied a TTL signal to mark the beginning of each period, thus providing angle information for the LDA measurements. Measurements were conducted for four axial positions in the slipstream of the pod drive models. The results show that the wake of contra-rotating propeller is more homogeneous than when they co-rotate. In agreement with the results of the force/momentum measurements and with hypotheses put forward in the literature (see e.g. Poehls in Entwurfsgrundlagen für Schraubenpropeller, 1984; Schneekluth in Hydromechanik zum Schiffsentwurf, 1988; Breslin and Andersen in Hydrodynamics of ship propellers, 1996

  18. Velocities in Solar Pores

    NASA Astrophysics Data System (ADS)

    Balasubramaniam, K. S.; Keil, S. L.; Smaldone, L. A.

    1996-05-01

    We investigate the three dimensional structure of solar pores and their surroundings using high spatial and spectral resolution data. We present evidence that surface velocities decrease around pores with a corresponding increase in the line-of-sight (LOS) velocities. LOS velocities in pores increase with the strength of the magnetic field. Surface velocities show convergence toward a weak downflow which appear to trace boundaries resembling meso-granular and super granular flows. The observed magnetic fields in the pores appear near these boundaries. We analyze the vertical velocity structure in pores and show that they generally have downflows decreasing exponentially with height, with a scale height of about 90 km. Evidence is also presented for the expanding nature of flux tubes. Finally we describe a phenomenological model for pores. This work was supported by AFOSR Task 2311G3. LAS was partially supported by the Progetto Nazionale Astrofisica e Fisica Cosmica of MURST and Scambi Internazionali of the Universita degli Studi di Napoli Frederico II. National Solar Observatory, NOAO, is operated for the National Science Foundation by AURA, Inc.

  19. Effect of kinesin velocity distribution on slow axonal transport

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Andrey

    2012-08-01

    The goal of this paper is to investigate the effect that a distribution of kinesin motor velocities could have on cytoskeletal element (CE) concentration waves in slow axonal transport. Previous models of slow axonal transport based on the stop-and-go hypothesis (P. Jung, A. Brown, Modeling the slowing of neurofilament transport along the mouse sciatic nerve, Physical Biology 6 (2009) 046002) assumed that in the anterograde running state all CEs move with one and the same velocity as they are propelled by kinesin motors. This paper extends the aforementioned theoretical approach by allowing for a distribution of kinesin motor velocities; the distribution is described by a probability density function (PDF). For a two kinetic state model (that accounts for the pausing and running populations of CEs) an analytical solution describing the propagation of the CE concentration wave is derived. Published experimental data are used to obtain an analytical expression for the PDF characterizing the kinesin velocity distribution; this analytical expression is then utilized as an input for computations. It is demonstrated that accounting for the kinesin velocity distribution increases the rate of spreading of the CE concentration waves, which is a significant improvement in the two kinetic state model.

  20. Magnetic-motor-root stimulation: review.

    PubMed

    Matsumoto, Hideyuki; Hanajima, Ritsuko; Terao, Yasuo; Ugawa, Yoshikazu

    2013-06-01

    Magnetic stimulation can activate the human central and peripheral nervous systems non-invasively and virtually painlessly. Magnetic stimulation over the spinal enlargements can activate spinal nerves at the neuroforamina (magnetic-neuroforamina stimulation). This stimulation method provides us with information related to the latency of compound-muscle action potential (CMAP), which is usually interpreted as peripheral motor-conduction time (PMCT). However, this stimulation method has faced several problems in clinical applications. One is that supramaximal CMAPs were unobtainable. Another is that magnetic stimulation did not usually activate the spinal nerves in the spinal canal, i.e., the cauda equina, which prevented an evaluation of its conduction. For these reasons, magnetic-neuroforamina stimulation was rarely used to evaluate the conduction of peripheral nerves. It was mainly used to evaluate the conduction of the corticospinal tract using the parameter of central motor-conduction time (CMCT), which was calculated by subtracting PMCT from the latency of motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) over the primary motor cortex. Recently, supramaximal stimulation has been achieved in magnetic-neuroforamina stimulation, and this has contributed to the measurement of both CMAP size and latency. The achievement of supramaximal stimulation is ascribed to the increase in magnetic-stimulator output and a novel coil, the magnetic augmented translumbosacral stimulation (MATS) coil. The most proximal part of the cauda equina can be reliably activated using the MATS coil (magnetic-conus stimulation), thus contributing to the measurement of cauda equina conduction time (CECT) and cortico-conus motor-conduction time (CCCT). These recent developments in magnetic-motor-root stimulation enable us to more precisely evaluate the conduction of the proximal part of peripheral nerves and that of the corticospinal tract for lower-limb muscles

  1. Dissociation of motor maturation.

    PubMed

    DiMario, Francis J

    2003-06-01

    We prospectively acquired clinical data regarding the presentation, evaluation, and developmental progress of all patients identified with dissociated motor maturation to define their clinical outcomes. Children (N = 8) referred for evaluation of suspected cerebral palsy because of delayed sitting or walking and identified to have dissociated motor maturation were followed with serial clinical examination. All displayed the characteristic "sitting on air" posture while held in vertical suspension and had otherwise normal developmental assessments. This posture is composed of the hips held in flexion and abduction with the knees extended and feet plantar or dorsiflexed. Three children were initially evaluated at 10 months of age owing to absence of sitting and five other children were evaluated at a mean of 14 months (range 12-19 months) owing to inability to stand. Follow-up evaluations were conducted over a mean of 10.5 months (range 5-34 months). Five children were born prematurely at 34 to 36 weeks gestation. Denver Developmental Screening Test and general and neurologic examinations were normal except to note hypotonia in six children and the "sitting on air" posture in all of the children. Four children have older siblings or parents who "walked late" (after 15 months). On average, the children attained sitting by 8 months (range 7-10 months). One child did not crawl prior to independent walking, two children scooted rather than crawled, and five children crawled at an average of 13.5 months (range 10-16 months). All children cruised by a mean of 18 months (range 16-21.5 months) and attained independent walking by 20.1 months (range 18-25 months). Neuroimaging and serum creatine kinase enzyme testing were normal in two children who were tested. These eight children conform to the syndrome of dissociated motor maturation. The "sitting on air" posture serves as a diagnostic sign and anticipated excellent prognosis, but follow-up is required to ensure a normal

  2. Blue Origin Conducts Pad Escape Test

    NASA Video Gallery

    Blue Origin conducted a successful pad escape test Oct. 19 at the company's West Texas launch site, firing its pusher escape motor and launching a full-scale suborbital crew capsule from a simulate...

  3. Interferometric phase velocity measurements

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Labelle, J.; Kelley, M. C.; Cahill, L. J., Jr.; Moore, T.; Arnoldy, R.

    1984-01-01

    Phase velocities of plasma waves near the lower hybrid frequency were measured with an interferometer composed of two spatially separated electron-density probes. The plasma waves were produced in the F-region ionosphere by an argon ion beam. By calculating the normalized cross spectrum of the plasma waves a coherency of .98 was estimated along with a maximum phase difference of pi/3 radians between the two probes. This implies that the wavelength was 6 meters compared to an O(+) gyroradius of 3.8 meters, and that the phase velocity was 45 km/sec compared to an ion-beam velocity of 12.4 km/sec. These numbers compare favorably with recent predictions of a nonresonant mode produced by a dense ion beam.

  4. Fluidic angular velocity sensor

    NASA Technical Reports Server (NTRS)

    Berdahl, C. M. (Inventor)

    1986-01-01

    A fluidic sensor providing a differential pressure signal proportional to the angular velocity of a rotary input is described. In one embodiment the sensor includes a fluid pump having an impeller coupled to a rotary input. A housing forming a constricting fluid flow chamber is connected to the fluid input of the pump. The housing is provided with a fluid flow restrictive input to the flow chamber and a port communicating with the interior of the flow chamber. The differential pressure signal measured across the flow restrictive input is relatively noise free and proportional to the square of the angular velocity of the impeller. In an alternative embodiment, the flow chamber has a generally cylindrical configuration and plates having flow restrictive apertures are disposed within the chamber downstream from the housing port. In this embodiment, the differential pressure signal is found to be approximately linear with the angular velocity of the impeller.

  5. Investigation of fluctuations in angular velocity in magnetic memory devices

    NASA Technical Reports Server (NTRS)

    Meshkis, Y. A.; Potsyus, Z. Y.

    1973-01-01

    The fluctuations in the angular velocity of individual assemblies of a precision mechanical system were analyzed. The system was composed of an electric motor and a magnetic drum which were connected by a flexible coupling. A dynamic model was constructed which took into account the absence of torsion in the rigid shafts of the electric motor drive rotor and the magnetic drum. The motion was described by Lagrange differential equations of the second kind. Curves are developed to show the nature of amplitude fluctuation of the magnetic drum angular velocity at a specific excitation frequency. Additional curves show the amplitudes of fluctuation of the magnetic drum angular velocity compared to the quantity of damping at specific frequencies.

  6. Velocity pump reaction turbine

    DOEpatents

    House, Palmer A.

    1984-01-01

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  7. Velocity pump reaction turbine

    DOEpatents

    House, Palmer A.

    1982-01-01

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  8. MSE velocity survey

    NASA Astrophysics Data System (ADS)

    Schimd, C.; Courtois, H.; Koda, J.

    2015-12-01

    A huge velocity survey based on the Maunakea Spectroscopic Explorer facility (MSE) is proposed, aiming at investigating the structure and dynamics of the cosmic web over 3π steradians up to ˜1 Gpc and at unprecedented spatial resolution, its relationship with the galaxy formation process, and the bias between galaxies and dark matter during the last three billions years. The cross-correlation of velocity and density fields will further allow the probe any deviation from General Relativity by measuring the the linear-growth rate of cosmic structures at precision competitive with high-redshift spectroscopic redshift surveys.

  9. Velocity pump reaction turbine

    SciTech Connect

    House, P.A.

    1984-02-07

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  10. Velocity pump reaction turbine

    SciTech Connect

    House, P.A.

    1982-06-01

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an interrotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal application

  11. Velocity pump reaction turbine

    DOEpatents

    House, P.A.

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  12. DVL Angular Velocity Recorder

    NASA Technical Reports Server (NTRS)

    Liebe, Wolfgang

    1944-01-01

    In many studies, especially of nonstationary flight motion, it is necessary to determine the angular velocities at which the airplane rotates about its various axes. The three-component recorder is designed to serve this purpose. If the angular velocity for one flight attitude is known, other important quantities can be derived from its time rate of change, such as the angular acceleration by differentiations, or - by integration - the angles of position of the airplane - that is, the angles formed by the airplane axes with the axis direction presented at the instant of the beginning of the motion that is to be investigated.

  13. A coin vibrational motor swimming at low Reynolds number

    NASA Astrophysics Data System (ADS)

    Quillen, Alice C.; Askari, Hesam; Kelley, Douglas H.; Friedmann, Tamar; Oakes, Patrick W.

    2016-12-01

    Low-cost coin vibrational motors, used in haptic feedback, exhibit rotational internal motion inside a rigid case. Because the motor case motion exhibits rotational symmetry, when placed into a fluid such as glycerin, the motor does not swim even though its oscillatory motions induce steady streaming in the fluid. However, a piece of rubber foam stuck to the curved case and giving the motor neutral buoyancy also breaks the rotational symmetry allowing it to swim. We measured a 1 cm diameter coin vibrational motor swimming in glycerin at a speed of a body length in 3 seconds or at 3 mm/s. The swim speed puts the vibrational motor in a low Reynolds number regime similar to bacterial motility, but because of the oscillations of the motor it is not analogous to biological organisms. Rather the swimming vibrational motor may inspire small inexpensive robotic swimmers that are robust as they contain no external moving parts. A time dependent Stokes equation planar sheet model suggests that the swim speed depends on a steady streaming velocity V stream Re s 1/2 U 0 where U 0 is the velocity of surface oscillations, and streaming Reynolds number Re s = U 0 2 /( ων) for motor angular frequency ω and fluid kinematic viscosity ν.

  14. 40 CFR 85.1506 - Inspection and testing of imported motor vehicles and engines.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Motor Vehicles and Motor Vehicle Engines § 85.1506 Inspection and testing of imported motor vehicles and... Enforcement Officers are authorized to conduct inspections and/or tests of vehicles or engines imported by the... authorized to proceed ex parte to seek warrants authorizing the inspection or testing of the motor...

  15. 40 CFR 85.1506 - Inspection and testing of imported motor vehicles and engines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Motor Vehicles and Motor Vehicle Engines § 85.1506 Inspection and testing of imported motor vehicles and... Enforcement Officers are authorized to conduct inspections and/or tests of vehicles or engines imported by the... authorized to proceed ex parte to seek warrants authorizing the inspection or testing of the motor...

  16. 40 CFR 85.1506 - Inspection and testing of imported motor vehicles and engines.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Motor Vehicles and Motor Vehicle Engines § 85.1506 Inspection and testing of imported motor vehicles and... Enforcement Officers are authorized to conduct inspections and/or tests of vehicles or engines imported by the... authorized to proceed ex parte to seek warrants authorizing the inspection or testing of the motor...

  17. 40 CFR 85.1506 - Inspection and testing of imported motor vehicles and engines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Motor Vehicles and Motor Vehicle Engines § 85.1506 Inspection and testing of imported motor vehicles and... Enforcement Officers are authorized to conduct inspections and/or tests of vehicles or engines imported by the... authorized to proceed ex parte to seek warrants authorizing the inspection or testing of the motor...

  18. 40 CFR 85.1506 - Inspection and testing of imported motor vehicles and engines.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Motor Vehicles and Motor Vehicle Engines § 85.1506 Inspection and testing of imported motor vehicles and... Enforcement Officers are authorized to conduct inspections and/or tests of vehicles or engines imported by the... authorized to proceed ex parte to seek warrants authorizing the inspection or testing of the motor...

  19. Modeling Terminal Velocity

    ERIC Educational Resources Information Center

    Brand, Neal; Quintanilla, John A.

    2013-01-01

    Using a simultaneously falling softball as a stopwatch, the terminal velocity of a whiffle ball can be obtained to surprisingly high accuracy with only common household equipment. This classroom activity engages students in an apparently daunting task that nevertheless is tractable, using a simple model and mathematical techniques at their…

  20. Directed flux motor

    NASA Technical Reports Server (NTRS)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2011-01-01

    A directed flux motor described utilizes the directed magnetic flux of at least one magnet through ferrous material to drive different planetary gear sets to achieve capabilities in six actuated shafts that are grouped three to a side of the motor. The flux motor also utilizes an interwoven magnet configuration which reduces the overall size of the motor. The motor allows for simple changes to modify the torque to speed ratio of the gearing contained within the motor as well as simple configurations for any number of output shafts up to six. The changes allow for improved manufacturability and reliability within the design.

  1. Controlled wind motor

    SciTech Connect

    Boswell, F.A.

    1983-12-27

    A mechanical sail including a rotatable mast, the mast including a top vane mount and a bottom vane mount, the mounts being spaced from each other on the mast and rotatable therewith, a series of rotatable vanes spaced from and surrounding the mast and supported by and between the mounts, cam operaters extending between the mounts and connected to the vanes for controlling the rotation of the vanes, a first controller associated with the mast below the bottom vane mount for controlling the cam operators, the first controller being movable vertically with respect to the mast, a second controller for moving the first controller vertically with respect to the mast, the vanes being flexible and bowed outwardly, the bottom vane mount being movable with respect to the mast and connected to the second controller whereby when the second controller is operated, the bottom vane mount will move toward the top vane mount causing the vanes to bow outwardly at a desired arc and whereby when the first controller is moved, the vanes are caused to rotate to the desired angle of attack with respect to wind velocity and direction. When the sail is connected to a motor drive, the vessel may be driven forward or rearward depending on the angle of attack of the vanes through 180/sup 0/.

  2. Expression of NR2B in cerebellar granule cells specifically facilitates effect of motor training on motor learning.

    PubMed

    Jiao, Jianwei; Nakajima, Akira; Janssen, William G M; Bindokas, Vytautas P; Xiong, Xiaoli; Morrison, John H; Brorson, James R; Tang, Ya-Ping

    2008-02-27

    It is believed that gene/environment interaction (GEI) plays a pivotal role in the development of motor skills, which are acquired via practicing or motor training. However, the underlying molecular/neuronal mechanisms are still unclear. Here, we reported that the expression of NR2B, a subunit of NMDA receptors, in cerebellar granule cells specifically enhanced the effect of voluntary motor training on motor learning in the mouse. Moreover, this effect was characterized as motor learning-specific and developmental stage-dependent, because neither emotional/spatial memory was affected nor was the enhanced motor learning observed when the motor training was conducted starting at the age of 3 months old in these transgenic mice. These results indicate that changes in the expression of gene(s) that are involved in regulating synaptic plasticity in cerebellar granule cells may constitute a molecular basis for the cerebellum to be involved in the GEI by facilitating motor skill learning.

  3. James Webb Space Telescope Deployment Brushless DC Motor Characteristics Analysis

    NASA Technical Reports Server (NTRS)

    Tran, Ahn N.

    2016-01-01

    A DC motor's performance is usually characterized by a series of tests, which are conducted by pass/fail criteria. In most cases, these tests are adequate to address the performance characteristics under environmental and loading effects with some uncertainties and decent power/torque margins. However, if the motor performance requirement is very stringent, a better understanding of the motor characteristics is required. The purpose of this paper is to establish a standard way to extract the torque components of the brushless motor and gear box characteristics of a high gear ratio geared motor from the composite geared motor testing and motor parameter measurement. These torque components include motor magnetic detent torque, Coulomb torque, viscous torque, windage torque, and gear tooth sliding torque. The Aerospace Corp bearing torque model and MPB torque models are used to predict the Coulomb torque of the motor rotor bearings and to model the viscous components. Gear tooth sliding friction torque is derived from the dynamo geared motor test data. With these torque data, the geared motor mechanical efficiency can be estimated and provide the overall performance of the geared motor versus several motor operating parameters such as speed, temperature, applied current, and transmitted power.

  4. Energy efficient motors

    NASA Astrophysics Data System (ADS)

    1995-01-01

    This TechData Sheet is intended to help activity personnel identify cost effective energy projects for energy efficient motors. With this guide an energy manager can identify when an energy efficient induction motor should be used.

  5. Introduction to ultrasonic motors

    SciTech Connect

    Sashida, Toshiiku; Kenjo, Takashi.

    1993-01-01

    The ultrasonic motor, invented in 1980, utilizes the piezoelectric effect in the ultrasonic frequency range to provide the motive force. (In conventional electric motors the motive force is electromagnetic.) The result is a motor with unusually good low-speed high-torque and power-to-weight characteristics. It has already found applications in camera autofocus mechanisms, medical equipment subject to high magnetic fields, and motorized car accessories. Its applications will increase as designers become more familiar with its unique characteristics. This book is the result of a collaboration between the inventor and an expert in conventional electric motors: the result is an introduction to the general theory presented in a way that links it to conventional motor theory. It will be invaluable both to motor designers and to those who design with and use electric motors as an introduction to this important new invention.

  6. Chronic motor tic disorder

    MedlinePlus

    Chronic vocal tic disorder; Tic - chronic motor tic disorder ... Chronic motor tic disorder is more common than Tourette syndrome . Chronic tics may be forms of Tourette syndrome. Tics usually start ...

  7. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  8. Energy-efficient electric motors study

    NASA Astrophysics Data System (ADS)

    1981-03-01

    A survey conducted of purchasers of integral horsepower polyphase motors measured current knowledge of and awareness of energy efficient motors, decision making criteria, information sources, purchase and usage patterns, and related factors. The data obtained were used for the electric motor market penetration analysis. Additionally, a telephone survey was made. The study also provides analyses of distribution channels, commercialization constraints, and the impacts of government programs and rising energy prices. Study findings, conclusions, and recommendations are presented. Sample questionnaires and copies of letters to respondents are presented in appendices as well as descriptions of the methods used.

  9. Smart motor technology

    NASA Technical Reports Server (NTRS)

    Packard, D.; Schmitt, D.

    1984-01-01

    Current spacecraft design relies upon microprocessor control; however, motors usually require extensive additional electronic circuitry to interface with these microprocessor controls. An improved control technique that allows a smart brushless motor to connect directly to a microprocessor control system is described. An actuator with smart motors receives a spacecraft command directly and responds in a closed loop control mode. In fact, two or more smart motors can be controlled for synchronous operation.

  10. Piezoelectric ultrasonic motors

    SciTech Connect

    Wallaschek, J.

    1994-12-31

    Piezoelectric ultrasonic motors are a new type of actuator. They are characterized by high torque at low rotational speed, simple mechanical design and good controllability. They also provide a high holding torque even if no power is applied. Compared to electromagnetic actuators the torque per volume ratio of piezoelectric ultrasonic motors can be higher by an order of magnitude. Recently various types of piezoelectric ultrasonic motors have been developed for industrial applications. This paper describes several types of piezoelectric ultrasonic motors.

  11. Alteration of Motor Network Function Following Injury

    DTIC Science & Technology

    2012-10-01

    unlikely system for spinal cord injury: namely crustacean motor networks such as the stomatogastric ganglion (STG)6. While the STG is an invertebrate...typically modify activity by regulating the properties or expression levels of subsets of ionic channels. In the stomatogastric system of crustaceans ...conductances preserves output in a computational model of a crustacean cardiac motor neuron. J Neurosci 30: 8637–8649, 2010. Baro DJ, Levini RM, Kim MT

  12. Superconductor-Magnet Bearings With Inherent Stability and Velocity-Independent Drag Torque

    NASA Technical Reports Server (NTRS)

    Lee, Eun-Jeong; Ma, Ki Bui; Wilson, Thomas L.; Chu, Wei-Kan

    1999-01-01

    A hybrid superconductor magnet bearing system has been developed based on passive magnetic levitation and the flux pinning effect of high-temperature superconductivity. The rationale lies in the unique capability of a high-temperature superconductor (HTS) to enhance system stability passively without power consumption. Characterization experiments have been conducted to understand its dynamic behavior and to estimate the required motor torque for its driving system design. These experiments show that the hybrid HTS-magnet bearing system has a periodic oscillation of drag torque due mainly to the nonuniform magnetic field density of permanent magnets. Furthermore, such a system also suffers from a small superimposed periodic oscillation introduced by the use of multiple HTS disks rather than a uniform annulus of HTS material. The magnitude of drag torque is velocity independent and very small. These results make this bearing system appealing for high-speed application. Finally, design guidelines for superconducting bearing systems are suggested based on these experimental results.

  13. Performance evaluation of a micro ultrasonic motor using a one-cubic-millimeter stator.

    PubMed

    Mashimo, Tomoaki

    2015-10-01

    A piezoelectric ultrasonic motor has two significant advantages, high energy density and simple structure, and these advantages can help in the miniaturization of the motor. We build a prototype micro ultrasonic motor using a stator with a volume of approximately 1 cubic millimeter. To evaluate its representative performance values (torque, angular velocity, and energy efficiency), we built an experimental setup and operated the prototype motor by varying experimental conditions, such as the preload between the stator and rotor and the amplitude of voltages applied to motor. The performance values obtained at the millimeter to sub-millimeter scale are discussed analytically using the macro scale models of ultrasonic motors. Experimentally, the prototype motor has generated a torque of more than 10 μNm with a 1-cubic-millimeter stator. The motor described herein is now the smallest micro ultrasonic motor with a practical torque, although its efficiency is still low.

  14. Motor systems and postural instability.

    PubMed

    Vassar, Rachel L; Rose, Jessica

    2014-01-01

    Acute alcohol intoxication and chronic alcohol dependence alter the neurologic control of posture and motor function. Ethanol delays the conduction of electric signals from the central nervous system to the muscles controlling posture and impairs the integration of sensory inputs required for maintaining vertical stance. Consequently, alcohol intoxication delays the ability to detect postural changes and enact the appropriate response. Common signs of acute alcohol intoxication include spinocerebellar and vestibulocerebellar ataxia, oculomotor changes, and increased reliance on visuospatial clues. Chronic alcoholism results in postural tremors and excessive sway during quiet stance that can persist even after sobriety is achieved. Underlying neurologic changes due to chronic alcoholism have been found to be associated with these characteristic postural changes and include decreased volume of the anterior superior vermis of the cerebellum, decreased connectivity within the corpus callosum, and overall cortical atrophy. Severity of motor impairments and other symptoms from alcoholism relate to a variety of factors, including duration of alcoholism, age, sex, and other health determinants and comorbidities. Imaging studies highlight the potential for partial recovery from neurologic and motor deficits caused by alcoholism. Emerging evidence on the motor and neurologic changes caused by alcohol dependence may allow for improved treatment and prevention of the morbidities associated with alcoholism.

  15. Cargo Transport by Two Coupled Myosin Va Motors on Actin Filaments and Bundles.

    PubMed

    Ali, M Yusuf; Vilfan, Andrej; Trybus, Kathleen M; Warshaw, David M

    2016-11-15

    Myosin Va (myoVa) is a processive, actin-based molecular motor essential for intracellular cargo transport. When a cargo is transported by an ensemble of myoVa motors, each motor faces significant physical barriers and directional challenges created by the complex actin cytoskeleton, a network of actin filaments and actin bundles. The principles that govern the interaction of multiple motors attached to the same cargo are still poorly understood. To understand the mechanical interactions between multiple motors, we developed a simple in vitro model in which two individual myoVa motors labeled with different-colored Qdots are linked via a third Qdot that acts as a cargo. The velocity of this two-motor complex was reduced by 27% as compared to a single motor, whereas run length was increased by only 37%, much less than expected from multimotor transport models. Therefore, at low ATP, which allowed us to identify individual motor steps, we investigated the intermotor dynamics within the two-motor complex. The randomness of stepping leads to a buildup of tension in the linkage between motors-which in turn slows down the leading motor-and increases the frequency of backward steps and the detachment rate. We establish a direct relationship between the velocity reduction and the distribution of intermotor distances. The analysis of run lengths and dwell times for the two-motor complex, which has only one motor engaged with the actin track, reveals that half of the runs are terminated by almost simultaneous detachment of both motors. This finding challenges the assumptions of conventional multimotor models based on consecutive motor detachment. Similar, but even more drastic, results were observed with two-motor complexes on actin bundles, which showed a run length that was even shorter than that of a single motor.

  16. Epithelial Conduction in Hydromedusae

    PubMed Central

    Mackie, G. O.; Passano, L. M.

    1968-01-01

    Sarsia, Euphysa, and other hydromedusae have been studied by electrophysiological techniques and are found to have nonnervous conducting epithelia resembling those described earlier for siphonophores. Simple, non-muscular epithelia fire singly or repetitively following brief electrical stimuli. The pulses recorded with suction electrodes are biphasic, initially positive, and show amplitudes of 0.75–2.0 mv, durations of 5–15 msec, and velocities of 15–35 cm/sec with short refractory periods. In the swimming muscle (myoepithelium) 2.0–4.0 mv composite events lasting 150–300 msec are associated with contraction waves. Propagation in nonnervous epithelia is typically all-or-none, nondecremental, and unpolarized. The subumbrellar endoderm lamella conducts independently of the adjacent ectoderm. The lower regions of the tentacles do not show propagated epithelial events. The spread of excitation in conducting epithelia and associated effector responses are described. Examples are given of interaction between events seemingly conducted in the nervous system and those in nonnervous epithelia. Either system may excite the other. Spontaneous activity, however, appears to originate in the nervous system. Conduction in nonnervous tissues is unaffected by excess Mg++ in concentrations suppressing presumed nervous activity, although this may not be a wholly adequate criterion for distinguishing components of the two systems. Evidence from old work by Romanes is considered in the light of these findings and the general significance of epithelial conduction is discussed. PMID:4386662

  17. Energy Velocity Defined by Brillouin

    NASA Astrophysics Data System (ADS)

    Hosono, Hiroyuki; Hosono, Toshio

    The physical meaning of the energy velocity in lossy Lorentz media is clarified. First, two expressions for the energy velocity, one by Brillouin and another by Diener, are examined. We show that, while Diener's is disqualified, Brillouin's is acceptable as energy velocity. Secondly, we show that the signal velocity defined by Brillouin and Baerwald is exactly identical with the Brillouin's energy velocity. Thirdly, by using triangle-modulated harmonic wave, we show that the superluminal group velocity plays its role as a revelator only after the arrival of the signal traveling at the subluminal energy velocity. In short, nothing moves at the group velocity, and every frequency component of a signal propagates at its own energy velocity.

  18. A Reconfigurable Stepping Motor

    NASA Astrophysics Data System (ADS)

    Rogers, Charles; Selvaggi, Richard

    2009-04-01

    Multiphase brushless actuators, commonly known as the stepper motors, are ubiquitous for many precision control applications. Developments in the microelectronics have lead to their use as efficient drive motors for modern electric vehicles. Understanding the physics and the control logic for interfacing these transducers continues to be important for scientists and engineers. An overview of the stepping motor principles and interfacing requirements is presented and a simple working model used to teach the concepts of stepper motors is described and demonstrated. This model was used to design a much larger stepper motor required to precisely rotate a massive optical system in the undergraduate advanced physics laboratory.

  19. Motor/generator

    DOEpatents

    Hickam, Christopher Dale

    2008-05-13

    A motor/generator is provided for connecting between a transmission input shaft and an output shaft of a prime mover. The motor/generator may include a motor/generator housing, a stator mounted to the motor/generator housing, a rotor mounted at least partially within the motor/generator housing and rotatable about a rotor rotation axis, and a transmission-shaft coupler drivingly coupled to the rotor. The transmission-shaft coupler may include a clamp, which may include a base attached to the rotor and a plurality of adjustable jaws.

  20. Solid propellant motor

    NASA Technical Reports Server (NTRS)

    Shafer, J. I.; Marsh, H. E., Jr. (Inventor)

    1978-01-01

    A case bonded end burning solid propellant rocket motor is described. A propellant with sufficiently low modulus to avoid chamber buckling on cooling from cure and sufficiently high elongation to sustain the stresses induced without cracking is used. The propellant is zone cured within the motor case at high pressures equal to or approaching the pressure at which the motor will operate during combustion. A solid propellant motor with a burning time long enough that its spacecraft would be limited to a maximum acceleration of less than 1 g is provided by one version of the case bonded end burning solid propellant motor of the invention.

  1. A neural circuit for angular velocity computation.

    PubMed

    Snider, Samuel B; Yuste, Rafael; Packer, Adam M

    2010-01-01

    In one of the most remarkable feats of motor control in the animal world, some Diptera, such as the housefly, can accurately execute corrective flight maneuvers in tens of milliseconds. These reflexive movements are achieved by the halteres, gyroscopic force sensors, in conjunction with rapidly tunable wing steering muscles. Specifically, the mechanosensory campaniform sensilla located at the base of the halteres transduce and transform rotation-induced gyroscopic forces into information about the angular velocity of the fly's body. But how exactly does the fly's neural architecture generate the angular velocity from the lateral strain forces on the left and right halteres? To explore potential algorithms, we built a neuromechanical model of the rotation detection circuit. We propose a neurobiologically plausible method by which the fly could accurately separate and measure the three-dimensional components of an imposed angular velocity. Our model assumes a single sign-inverting synapse and formally resembles some models of directional selectivity by the retina. Using multidimensional error analysis, we demonstrate the robustness of our model under a variety of input conditions. Our analysis reveals the maximum information available to the fly given its physical architecture and the mathematics governing the rotation-induced forces at the haltere's end knob.

  2. Mechanism of cooperative behaviour in systems of slow and fast molecular motors.

    PubMed

    Larson, Adam G; Landahl, Eric C; Rice, Sarah E

    2009-06-28

    Two recent theoretical advances have described cargo transport by multiple identical motors and by multiple oppositely directed, but otherwise identical motors [M. J. Muller, S. Klumpp and R. Lipowsky, Proc. Natl. Acad. Sci. U. S. A., 2008, 105(12), 4609-4614; S. Klumpp and R. Lipowsky, Proc. Natl. Acad. Sci. U. S. A., 2005, 102(48), 17284-17289]. Here, we combine a similar theoretical approach with a simple experiment to describe the behaviour of a system comprised of slow and fast molecular motors having the same directionality. We observed the movement of microtubules by mixtures of slow and fast kinesin motors attached to a glass coverslip in a classic sliding filament assay. The motors are identical, except that the slow ones contain five point mutations that collectively reduce their velocity approximately 15-fold without compromising maximal ATPase activity. Our results indicate that a small fraction of fast motors are able to accelerate the dissociation of slow motors from microtubules. Because of this, a sharp, highly cooperative transition occurs from slow to fast microtubule movement as the relative number of fast motors in the assay is increased. Microtubules move at half-maximal velocity when only 15% of the motors in the assay are fast. Our model indicates that this behaviour depends primarily on the relative motor velocities and the asymmetry between their forward and backward dissociation forces. It weakly depends on the number of motors and their processivity. We predict that movement of cargoes bound to two types of motors having very different velocities will be dominated by one or the other motor. Therefore, cargoes can potentially undergo abrupt changes in movement in response to regulatory mechanisms acting on only a small fraction of motors.

  3. Dynamics of single-motor molecules: the thermal ratchet model.

    PubMed Central

    Córdova, N J; Ermentrout, B; Oster, G F

    1992-01-01

    We present a model for single-motor molecules--myosin, dynein, or kinesin--that is powered either by thermal fluctuations or by conformational change. In the thermally driven model, the cross-bridge fluctuates about its equilibrium position against an elastic restoring force. The attachment and detachment of the cross-bridge are determined by modeling the electrostatic attraction between the cross-bridge and the fiber binding sites, so that binding depends on the strain in the cross-bridge and its velocity with respect to the fiber. The model correctly predicts the empirical force-velocity characteristics for populations of motor molecules. For a single motor, the apparent cross-bridge step size per ATP hydrolysis depends nonlinearly on the load. When the elastic energy driving the cross-bridge is generated by a conformational change, the velocity and duty cycle are much larger than is observed experimentally for myosin. Images PMID:1530889

  4. Development of Ulta-Efficient Electric Motors

    SciTech Connect

    Shoykhet, B.; Schiferl, R.; Duckworth, R.; Rey, C.M.; Schwenterly, S.W.; Gouge, M.J.

    2008-05-01

    . Between the HTS field winding and the physical air gap is a series of concentric cylinders that act as vacuum insulation space walls as well as conducting paths for induced currents to flow in order to shield the HTS winding and the rotor cold space from time dependent fields. These time dependent fields may be caused by rotor hunting, during a change in motor load, or by non-fundamental component voltages and currents applied by the inverter. These motors are variable speed controlled by the inverter. Common large motor utility and industrial applications are pump and fan drives that are best suited by a variable speed motor. Inverter control of the HTS motor eliminates the need to design the rotor for line starting, which would dump a large amount of heat into the rotor that would then heavily tax the cryogenic cooling system. The field winding is fed by a brushless exciter that provides DC current to the HTS rotor winding. The stator winding is air or water cooled. Technical and commercial hurdles to industrial HTS motor product introduction and customer acceptance include (1) the high cost of HTS wire and the cryogenic cooling system components, (2) customer concerns about reliability of HTS motors, and (3) the ability to attain the loss reduction potential of large HTS motors. Reliance Electric has demonstrated a number of HTS based electric motors up to a 1000 hp, variable speed synchronous motor with an HTS field winding in the year 2000. In 2001 this motor was tested to 1600 hp with a sinusoidal (constant frequency) supply. Figure 1-2 shows the HTS motor on the dynamometer test stand in the Reliance Electric test lab. The extensive test program of the 1000 hp motor successfully demonstrated the technical feasibility of large HTS motors and the basic technologies involved, however the test results did indicate the need for design refinements. In addition, test results served to identify other more fundamental critical technology issues, and revealed the need to

  5. Motor degradation prediction methods

    SciTech Connect

    Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

    1996-12-01

    Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor`s duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures.

  6. Motorized support jack

    DOEpatents

    Haney, Steven J.; Herron, Donald Joe

    2001-01-01

    A compact, vacuum compatible motorized jack for supporting heavy loads and adjusting their positions is provided. The motorized jack includes: (a) a housing having a base; (b) a first roller device that provides a first slidable surface and that is secured to the base; (c) a second roller device that provides a second slidable surface and that has an upper surface; (d) a wedge that is slidably positioned between the first roller device and the second roller device so that the wedge is in contact with the first slidable surface and the second slidable surface; (e) a motor; and (d) a drive mechanism that connects the motor and the wedge to cause the motor to controllably move the wedge forwards or backwards. Individual motorized jacks can support and lift of an object at an angle. Two or more motorized jacks can provide tip, tilt and vertical position adjustment capabilities.

  7. Motorized support jack

    DOEpatents

    Haney, Steven J.; Herron, Donald Joe

    2003-05-13

    A compact, vacuum compatible motorized jack for supporting heavy loads and adjusting their positions is provided. The motorized jack includes: (a) a housing having a base; (b) a first roller device that provides a first slidable surface and that is secured to the base; (c) a second roller device that provides a second slidable surface and that has an upper surface; (d) a wedge that is slidably positioned between the first roller device and the second roller device so that the wedge is in contact with the first slidable surface and the second slidable surface; (e) a motor; and (d) a drive mechanism that connects the motor and the wedge to cause the motor to controllably move the wedge forwards or backwards. Individual motorized jacks can support and lift of an object at an angle. Two or more motorized jacks can provide tip, tilt and vertical position adjustment capabilities.

  8. Appropriate Conduct

    ERIC Educational Resources Information Center

    Di Lullo, Louis

    2004-01-01

    Many years ago when the author assumed the role of assistant principal for school climate, discipline, and attendance, he inherited many school policies and guidelines that were outdated, unfair, and without merit in the current school climate. Because the school conduct code had not been revised since the school opened in 1960, many of the…

  9. Motor adaptation and generalization of reaching movements using motor primitives based on spatial coordinates

    PubMed Central

    Sejnowski, Terrence J.

    2014-01-01

    The brain processes sensory and motor information in a wide range of coordinate systems, ranging from retinal coordinates in vision to body-centered coordinates in areas that control musculature. Here we focus on the coordinate system used in the motor cortex to guide actions and examine physiological and psychophysical evidence for an allocentric reference frame based on spatial coordinates. When the equations of motion governing reaching dynamics are expressed as spatial vectors, each term is a vector cross product between a limb-segment position and a velocity or acceleration. We extend this computational framework to motor adaptation, in which the cross-product terms form adaptive bases for canceling imposed perturbations. Coefficients of the velocity- and acceleration-dependent cross products are assumed to undergo plastic changes to compensate the force-field or visuomotor perturbations. Consistent with experimental findings, each of the cross products had a distinct reference frame, which predicted how an acquired remapping generalized to untrained location in the workspace. In response to force field or visual rotation, mainly the coefficients of the velocity- or acceleration-dependent cross products adapted, leading to transfer in an intrinsic or extrinsic reference frame, respectively. The model further predicted that remapping of visuomotor rotation should under- or overgeneralize in a distal or proximal workspace. The cross-product bases can explain the distinct patterns of generalization in visuomotor and force-field adaptation in a unified way, showing that kinematic and dynamic motor adaptation need not arise through separate neural substrates. PMID:25429111

  10. Motor adaptation and generalization of reaching movements using motor primitives based on spatial coordinates.

    PubMed

    Tanaka, Hirokazu; Sejnowski, Terrence J

    2015-02-15

    The brain processes sensory and motor information in a wide range of coordinate systems, ranging from retinal coordinates in vision to body-centered coordinates in areas that control musculature. Here we focus on the coordinate system used in the motor cortex to guide actions and examine physiological and psychophysical evidence for an allocentric reference frame based on spatial coordinates. When the equations of motion governing reaching dynamics are expressed as spatial vectors, each term is a vector cross product between a limb-segment position and a velocity or acceleration. We extend this computational framework to motor adaptation, in which the cross-product terms form adaptive bases for canceling imposed perturbations. Coefficients of the velocity- and acceleration-dependent cross products are assumed to undergo plastic changes to compensate the force-field or visuomotor perturbations. Consistent with experimental findings, each of the cross products had a distinct reference frame, which predicted how an acquired remapping generalized to untrained location in the workspace. In response to force field or visual rotation, mainly the coefficients of the velocity- or acceleration-dependent cross products adapted, leading to transfer in an intrinsic or extrinsic reference frame, respectively. The model further predicted that remapping of visuomotor rotation should under- or overgeneralize in a distal or proximal workspace. The cross-product bases can explain the distinct patterns of generalization in visuomotor and force-field adaptation in a unified way, showing that kinematic and dynamic motor adaptation need not arise through separate neural substrates.

  11. Acoustic velocity meter systems

    USGS Publications Warehouse

    Laenen, Antonius

    1985-01-01

    Acoustic velocity meter (AVM) systems operate on the principles that the point-to-point upstream traveltime of an acoustic pulse is longer than the downstream traveltime and that this difference in traveltime can be accurately measured by electronic devices. An AVM system is capable of recording water velocity (and discharge) under a wide range of conditions, but some constraints apply: 1. Accuracy is reduced and performance is degraded if the acoustic path is not a continuous straight line. The path can be bent by reflection if it is too close to a stream boundary or by refraction if it passes through density gradients resulting from variations in either water temperature or salinity. For paths of less than 100 m, a temperature gradient of 0.1' per meter causes signal bending less than 0.6 meter at midchannel, and satisfactory velocity results can be obtained. Reflection from stream boundaries can cause signal cancellation if boundaries are too close to signal path. 2. Signal strength is attenuated by particles or bubbles that absorb, spread, or scatter sound. The concentration of particles or bubbles that can be tolerated is a function of the path length and frequency of the acoustic signal. 3. Changes in streamline orientation can affect system accuracy if the variability is random. 4. Errors relating to signal resolution are much larger for a single threshold detection scheme than for multiple threshold schemes. This report provides methods for computing the effect of various conditions on the accuracy of a record obtained from an AVM. The equipment must be adapted to the site. Field reconnaissance and preinstallation analysis to detect possible problems are critical for proper installation and operation of an AVM system.

  12. Neutron Velocity Selector

    NASA Astrophysics Data System (ADS)

    Fermi, Enrico

    This Patent presents a detailed description of the construction and operation of a velocity selector for neutrons with velocities up to 6000÷7000 m/s. This apparatus employs a rotating shutter designed in such a way that neutrons are passed during a portion of each rotation of the shutter, the shutter blocking all neutron radiation at other times. The selector is built up with alternate laminations of a material with high neutron capture cross section (such as, for example, cadmium, boron or gadolinium), and parallel laminations of a material with low capture probability (such as, for example, aluminium, magnesium or beryllium). This is required in order to provide a path through the shutter to the neutrons, which then pass into a ionization chamber. The timing mechanism, adopted to activate or deactivate the neutron detection, and measuring means at given times following each opening or closing of the shutter, is electronic (not mechanic), controlled by a photocell unit. The reference published article for the main topic of the present Patent is [Fermi (1947)].

  13. A simple theory of motor protein kinetics and energetics. II.

    PubMed

    Qian, H

    2000-01-10

    A three-state stochastic model of motor protein [Qian, Biophys. Chem. 67 (1997) pp. 263-267] is further developed to illustrate the relationship between the external load on an individual motor protein in aqueous solution with various ATP concentrations and its steady-state velocity. A wide variety of dynamic motor behavior are obtained from this simple model. For the particular case of free-load translocation being the most unfavorable step within the hydrolysis cycle, the load-velocity curve is quasi-linear, V/Vmax = (cF/Fmax-c)/(1-c), in contrast to the hyperbolic relationship proposed by A.V. Hill for macroscopic muscle. Significant deviation from the linearity is expected when the velocity is less than 10% of its maximal (free-load) value--a situation under which the processivity of motor diminishes and experimental observations are less certain. We then investigate the dependence of load-velocity curve on ATP (ADP) concentration. It is shown that the free load Vmax exhibits a Michaelis-Menten like behavior, and the isometric Fmax increases linearly with ln([ATP]/[ADP]). However, the quasi-linear region is independent of the ATP concentration, yielding an apparently ATP-independent maximal force below the true isometric force. Finally, the heat production as a function of ATP concentration and external load are calculated. In simple terms and solved with elementary algebra, the present model provides an integrated picture of biochemical kinetics and mechanical energetics of motor proteins.

  14. Ultra-Compact Motor Controller

    NASA Technical Reports Server (NTRS)

    Townsend, William T.; Crowell, Adam; Hauptman, Traveler; Pratt, Gill Andrews

    2012-01-01

    This invention is an electronically commutated brushless motor controller that incorporates Hall-array sensing in a small, 42-gram package that provides 4096 absolute counts per motor revolution position sensing. The unit is the size of a miniature hockey puck, and is a 44-pin male connector that provides many I/O channels, including CANbus, RS-232 communications, general-purpose analog and digital I/O (GPIO), analog and digital Hall inputs, DC power input (18-90 VDC, 0-l0 A), three-phase motor outputs, and a strain gauge amplifier. This controller replaces air cooling with conduction cooling via a high-thermal-conductivity epoxy casting. A secondary advantage of the relatively good heat conductivity that comes with ultra-small size is that temperature differences within the controller become smaller, so that it is easier to measure the hottest temperature in the controller with fewer temperature sensors, or even one temperature sensor. Another size-sensitive design feature is in the approach to electrical noise immunity. At a very small size, where conduction paths are much shorter than in conventional designs, the ground becomes essentially isopotential, and so certain (space-consuming) electrical noise control components become unnecessary, which helps make small size possible. One winding-current sensor, applied to all of the windings in fast sequence, is smaller and wastes less power than the two or more sensors conventionally used to sense and control winding currents. An unexpected benefit of using only one current sensor is that it actually improves the precision of current control by using the "same" sensors to read each of the three phases. Folding the encoder directly into the controller electronics eliminates a great deal of redundant electronics, packaging, connectors, and hook-up wiring. The reduction of wires and connectors subtracts substantial bulk and eliminates their role in behaving as EMI (electro-magnetic interference) antennas. A shared

  15. Dissociating motor cortex from the motor

    PubMed Central

    Schieber, Marc H

    2011-01-01

    Abstract During closed-loop control of a brain–computer interface, neurons in the primary motor cortex can be intensely active even though the subject may be making no detectable movement or muscle contraction. How can neural activity in the primary motor cortex become dissociated from the movements and muscles of the native limb that it normally controls? Here we examine circumstances in which motor cortex activity is known to dissociate from movement – including mental imagery, visuo-motor dissociation and instructed delay. Many such motor cortex neurons may be related to muscle activity only indirectly. Furthermore, the integration of thousands of synaptic inputs by individual α-motoneurons means that under certain circumstances even cortico-motoneuronal cells, which make monosynaptic connections to α-motoneurons, can become dissociated from muscle activity. The natural ability of motor cortex neurons under voluntarily control to become dissociated from bodily movement may underlie the utility of this cortical area for controlling brain–computer interfaces. PMID:22005673

  16. Transport of organelles by elastically coupled motor proteins.

    PubMed

    Bhat, Deepak; Gopalakrishnan, Manoj

    2016-07-01

    Motor-driven intracellular transport is a complex phenomenon where multiple motor proteins simultaneously attached on to a cargo engage in pulling activity, often leading to tug-of-war, displaying bidirectional motion. However, most mathematical and computational models ignore the details of the motor-cargo interaction. A few studies have focused on more realistic models of cargo transport by including elastic motor-cargo coupling, but either restrict the number of motors and/or use purely phenomenological forms for force-dependent hopping rates. Here, we study a generic model in which N motors are elastically coupled to a cargo, which itself is subjected to thermal noise in the cytoplasm and to an additional external applied force. The motor-hopping rates are chosen to satisfy detailed balance with respect to the energy of elastic stretching. With these assumptions, an (N + 1) -variable master equation is constructed for dynamics of the motor-cargo complex. By expanding the hopping rates to linear order in fluctuations in motor positions, we obtain a linear Fokker-Planck equation. The deterministic equations governing the average quantities are separated out and explicit analytical expressions are obtained for the mean velocity and diffusion coefficient of the cargo. We also study the statistical features of the force experienced by an individual motor and quantitatively characterize the load-sharing among the cargo-bound motors. The mean cargo velocity and the effective diffusion coefficient are found to be decreasing functions of the stiffness. While the increase in the number of motors N does not increase the velocity substantially, it decreases the effective diffusion coefficient which falls as 1/N asymptotically. We further show that the cargo-bound motors share the force exerted on the cargo equally only in the limit of vanishing elastic stiffness; as stiffness is increased, deviations from equal load sharing are observed. Numerical simulations agree with

  17. Motor imagery based brain-computer interfaces: An emerging technology to rehabilitate motor deficits.

    PubMed

    Alonso-Valerdi, Luz Maria; Salido-Ruiz, Ricardo Antonio; Ramirez-Mendoza, Ricardo A

    2015-12-01

    When the sensory-motor integration system is malfunctioning provokes a wide variety of neurological disorders, which in many cases cannot be treated with conventional medication, or via existing therapeutic technology. A brain-computer interface (BCI) is a tool that permits to reintegrate the sensory-motor loop, accessing directly to brain information. A potential, promising and quite investigated application of BCI has been in the motor rehabilitation field. It is well-known that motor deficits are the major disability wherewith the worldwide population lives. Therefore, this paper aims to specify the foundation of motor rehabilitation BCIs, as well as to review the recent research conducted so far (specifically, from 2007 to date), in order to evaluate the suitability and reliability of this technology. Although BCI for post-stroke rehabilitation is still in its infancy, the tendency is towards the development of implantable devices that encompass a BCI module plus a stimulation system.

  18. Indentation of aluminium foam at low velocity

    NASA Astrophysics Data System (ADS)

    Shi, Xiaopeng; Miao, Yinggang; Liu, Shuangyan; Li, Yulong; Lu, Guoxing

    2015-09-01

    The indentation behaviour of aluminium foams at low velocity (10 m/s ˜ 30 m/s) was investigated both in experiments and numerical simulation in this paper. A flat-ended indenter was used and the force-displacement history was recorded. The Split Hopkinson Pressure bar was used to obtain the indentation velocity and forces in the dynamic experiments. Because of the low strength of the aluminium foam, PMMA bar was used, and the experimental data were corrected using Bacon's method. The energy absorption characteristics varying with impact velocity were then obtained. It was found that the energy absorption ability of aluminium foam gradually increases in the quasi-static regime and shows a significant increase at ˜10 m/s velocity. Numerical simulation was also conducted to investigate this process. A 3D Voronoi model was used and models with different relative densities were investigated as well as those with different failure strain. The indentation energy increases with both the relative density and failure strain. The analysis of the FE model implies that the significant change in energy absorption ability of aluminium foam in indentation at ˜10 m/s velocity may be caused by plastic wave effect.

  19. Ratchet models of molecular motors

    NASA Astrophysics Data System (ADS)

    Jaster, Nicole

    2003-09-01

    Transport processes in and of cells are of major importance for the survival of the organism. Muscles have to be able to contract, chromosomes have to be moved to opposing ends of the cell during mitosis, and organelles, which are compartments enclosed by membranes, have to be transported along molecular tracks. Molecular motors are proteins whose main task is moving other molecules.For that purpose they transform the chemical energy released in the hydrolysis of ATP into mechanical work. The motors of the cytoskeleton belong to the three super families myosin, kinesin and dynein. Their tracks are filaments of the cytoskeleton, namely actin and the microtubuli. Here, we examine stochastic models which are used for describing the movements of these linear molecular motors. The scale of the movements comprises the regime of single steps of a motor protein up to the directed walk along a filament. A single step bridges around 10 nm, depending on the protein, and takes about 10 ms, if there is enough ATP available. Our models comprise M states or conformations the motor can attain during its movement along a one-dimensional track. At K locations along the track transitions between the states are possible. The velocity of the protein depending on the transition rates between the single states can be determined analytically. We calculate this velocity for systems of up to four states and locations and are able to derive a number of rules which are helpful in estimating the behaviour of an arbitrary given system. Beyond that we have a look at decoupled subsystems, i.e., one or a couple of states which have no connection to the remaining system. With a certain probability a motor undergoes a cycle of conformational changes, with another probability an independent other cycle. Active elements in real transport processes by molecular motors will not be limited to the transitions between the states. In distorted networks or starting from the discrete Master equation of the

  20. Cooperative behavior of molecular motors: Cargo transport and traffic phenomena

    NASA Astrophysics Data System (ADS)

    Lipowsky, Reinhard; Beeg, Janina; Dimova, Rumiana; Klumpp, Stefan; Müller, Melanie J. I.

    2010-01-01

    All eukaryotic cells including those of our own body contain complex transport systems based on molecular motors which walk along cytoskeletal filaments. These motors are rather small and make discrete mechanical steps with a step size of the order of 10 nm but are able to pull cargo particles over much larger distances, from micrometers up to meters. In vivo, the intracellular cargos include large membrane-bounded organelles, smaller vesicles, a subset of mRNAs, cytoskeletal filaments, and various protein building blocks, which are transported between different cell compartments. This cargo transport is usually performed by teams of motors. If all motors belong to the same molecular species, the cooperative action of the motors leads to uni-directional transport with a strongly increased run length and with a characteristic force dependence of the velocity distributions. If two antagonistic teams of motors pull on the same cargo particle, they perform a stochastic tug-of-war, which is characterized by a subtle force balance between the two motor teams and leads to several distinct patterns of bi-directional transport. So far, all experimental observations on bi-directional transport are consistent with such a tug-of-war. If many motors and/or cargo particles are transported along the filaments, one encounters various traffic phenomena. Depending on their mutual interactions and the compartment geometry, the motors form various spatio-temporal patterns such as traffic jams, and undergo nonequilibrium phase transitions between different patterns of transport.

  1. Unitaxial constant velocity microactuator

    DOEpatents

    McIntyre, Timothy J.

    1994-01-01

    A uniaxial drive system or microactuator capable of operating in an ultra-high vacuum environment. The mechanism includes a flexible coupling having a bore therethrough, and two clamp/pusher assemblies mounted in axial ends of the coupling. The clamp/pusher assemblies are energized by voltage-operated piezoelectrics therewithin to operatively engage the shaft and coupling causing the shaft to move along its rotational axis through the bore. The microactuator is capable of repeatably positioning to sub-manometer accuracy while affording a scan range in excess of 5 centimeters. Moreover, the microactuator generates smooth, constant velocity motion profiles while producing a drive thrust of greater than 10 pounds. The system is remotely controlled and piezoelectrically driven, hence minimal thermal loading, vibrational excitation, or outgassing is introduced to the operating environment.

  2. Unitaxial constant velocity microactuator

    DOEpatents

    McIntyre, T.J.

    1994-06-07

    A uniaxial drive system or microactuator capable of operating in an ultra-high vacuum environment is disclosed. The mechanism includes a flexible coupling having a bore therethrough, and two clamp/pusher assemblies mounted in axial ends of the coupling. The clamp/pusher assemblies are energized by voltage-operated piezoelectrics therewithin to operatively engage the shaft and coupling causing the shaft to move along its rotational axis through the bore. The microactuator is capable of repeatably positioning to sub-nanometer accuracy while affording a scan range in excess of 5 centimeters. Moreover, the microactuator generates smooth, constant velocity motion profiles while producing a drive thrust of greater than 10 pounds. The system is remotely controlled and piezoelectrically driven, hence minimal thermal loading, vibrational excitation, or outgassing is introduced to the operating environment. 10 figs.

  3. Piezoelectric Motors and Transformers

    NASA Astrophysics Data System (ADS)

    Uchino, K.

    Piezoelectric ceramics forms a new field between electronic and structural ceramics [1-4]. Application fields are classified into three categories: positioners, motors, and vibration suppressors. From the market research result for 80 Japanese component industries in 1992, tiny motors in the range of 5-8 mm are required in large numbers for office and portable equipment; the conventional electromagnetic (EM) motors are rather difficult to produce in this size with sufficient energy efficiency, while Silicon MEMS actuators are too small to be used in practice. Piezoelectric ultrasonic motors whose efficiency is insensitive to size are superior in the millimeter motor area. The manufacturing precision of optical instruments such as lasers and cameras, and the positioning accuracy for fabricating semiconductor chips are of the order of 0.1μm which is much smaller than the backlash of the EM motors. Vibration suppression in space structures and military vehicles also require compact but mighty piezoelectric actuators.

  4. Miniature laser ignited bellows motor

    NASA Technical Reports Server (NTRS)

    Renfro, Steven L.; Beckman, Tom M.

    1994-01-01

    A miniature optically ignited actuation device has been demonstrated using a laser diode as an ignition source. This pyrotechnic driven motor provides between 4 and 6 lbs of linear force across a 0.090 inch diameter surface. The physical envelope of the device is 1/2 inch long and 1/8 inch diameter. This unique application of optical energy can be used as a mechanical link in optical arming systems or other applications where low shock actuation is desired and space is limited. An analysis was performed to determine pyrotechnic materials suitable to actuate a bellows device constructed of aluminum or stainless steel. The aluminum bellows was chosen for further development and several candidate pyrotechnics were evaluated. The velocity profile and delivered force were quantified using an non-intrusive optical motion sensor.

  5. Tug of War in Motor Protein Ensembles Revealed with a Programmable DNA Origami Scaffold

    PubMed Central

    Derr, N. D.; Goodman, B. S.; Jungmann, R.; Leschziner, A. E.; Shih, W. M.; Reck-Peterson, S. L.

    2013-01-01

    Cytoplasmic dynein and kinesin-1 are opposite-polarity, microtubule-based motors that transport a wide variety of cargo in eukaryotic cells. Many cellular cargos demonstrate bi-directional movement due to the presence of ensembles of dynein and kinesin, but are ultimately sorted with spatial and temporal precision. To investigate the mechanisms that coordinate motor ensemble behavior, we built a programmable synthetic cargo using three-dimensional DNA origami to which varying numbers of DNA oligonucleotide-linked motors could be attached, allowing control of motor type, number, spacing, and orientation in vitro. In ensembles of 1–7 identical-polarity motors, motor number had minimal affect on directional velocity, while ensembles of opposite-polarity motors engaged in a tug of war resolvable by disengaging one motor species. PMID:23065903

  6. Transition from velocity weakening to strong velocity strengthening friction in dense granular shear experiments

    NASA Astrophysics Data System (ADS)

    Kuwano, O.; Ando, R.; Hatano, T.

    2009-12-01

    In a "microscopic" view, natural faults generally consist of gouge layers, the frictional properties of which are much richer than the celebrated rate- and state-dependent friction law. One of such examples is intermediate-to-high slip velocity (mm/sec-m/sec) regime, where anomalous weakening and, at the same time, strengthening are reported; the results differ from experiments to experiments. In order to understand such a complicated phenomenon, one must carefully control the physical processes that potentially affect the frictional properties. We seek the nature of granular friction from many-body interaction. Toward this end, experiments are done on dry glass beads layer under low normal stress to exclude the possible effect of melting, comminution, silica gel formation, thermal decomposition, moisture, and so on. In this study, friction experiments of the glass-beads layers at slip rate of 10μm/s-1m/s were conducted. Experiments were performed at constant normal stresses of 10-50kPa using a ring shear apparatus with inner/outer diameters of 15mm/25mm. We used spherical soda-lime glass beads of diameter 200-300μm. The thickness of beads layer is about 2mm. Temperature beneath the lower plate was set to 25 degrees C and kept constant with Peltier Plate. It is found that the power-law dependence of the friction coefficient on slip velocity overwhelms the logarithmic rate dependence which originates from the rate-state friction law. Friction coefficient decreases with increasing slip velocity in low slip velocity regime (10μm/s~1cm/s) with velocity dependence of about -0.01 per decade of slip velocity. In high slip velocity regime (1cm/s~1m/s) it becomes velocity strengthening. This velocity strengthening regime is consistent with the power-law friction in closely-packed granular materials found by one of the authors (Hatano, 2007) by a numerical experiment using the discrete element method. Granular layer dilates with increasing slip velocity in higher velocity

  7. Visual control of walking velocity.

    PubMed

    François, Matthieu; Morice, Antoine H P; Bootsma, Reinoud J; Montagne, Gilles

    2011-06-01

    Even if optical correlates of self-motion velocity have already been identified, their contribution to the control of displacement velocity remains to be established. In this study, we used a virtual reality set-up coupled to a treadmill to test the role of both Global Optic Flow Rate (GOFR) and Edge Rate (ER) in the regulation of walking velocity. Participants were required to walk at a constant velocity, corresponding to their preferred walking velocity, while eye height and texture density were manipulated. This manipulation perturbed the natural relationship between the actual walking velocity and its optical specification by GOFR and ER, respectively. Results revealed that both these sources of information are indeed used by participants to control walking speed, as demonstrated by a slowing down of actual walking velocity when the optical specification of velocity by either GOFR or ER gives rise to an overestimation of actual velocity, and vice versa. Gait analyses showed that these walking velocity adjustments result from simultaneous adaptations in both step length and step duration. The role of visual information in the control of self-motion velocity is discussed in relation with other factors.

  8. Cryogenic Electric Motor Tested

    NASA Technical Reports Server (NTRS)

    Brown, Gerald V.

    2004-01-01

    Technology for pollution-free "electric flight" is being evaluated in a number of NASA Glenn Research Center programs. One approach is to drive propulsive fans or propellers with electric motors powered by fuel cells running on hydrogen. For large transport aircraft, conventional electric motors are far too heavy to be feasible. However, since hydrogen fuel would almost surely be carried as liquid, a propulsive electric motor could be cooled to near liquid hydrogen temperature (-423 F) by using the fuel for cooling before it goes to the fuel cells. Motor windings could be either superconducting or high purity normal copper or aluminum. The electrical resistance of pure metals can drop to 1/100th or less of their room-temperature resistance at liquid hydrogen temperature. In either case, super or normal, much higher current density is possible in motor windings. This leads to more compact motors that are projected to produce 20 hp/lb or more in large sizes, in comparison to on the order of 2 hp/lb for large conventional motors. High power density is the major goal. To support cryogenic motor development, we have designed and built in-house a small motor (7-in. outside diameter) for operation in liquid nitrogen.

  9. Sensorless, online motor diagnostics

    SciTech Connect

    Kliman, G.B.; Premerlani, W.J.; Yazici, B.; Koegl, R.A.; Mazereeuw, J.

    1997-04-01

    Electric motors play a very important role in the safe and efficient running of any industrial plant. Early detection of abnormalities in the motors will help avoid expensive failures. Motor current signature analysis (MCSA) implemented in a computer-based motor monitor can contribute to such condition-based maintenance functions. Such a system may also detect an abnormality in the process as well as the motor. Extensive online monitoring of the motors can lead to greater plant availability, extended plant life, higher quality product, and smoother plant operation. With advances in digital technology over the last several years, adequate data processing capability is now available on cost-effective, microprocessor-based, protective-relay platforms to monitor motors for a variety of abnormalities in addition to the normal protection functions. Such multifunction monitors, first introduced by Multilin, are displacing the multiplicity of electromechanical devices commonly applied for many years. Following some background information on motor monitoring, this article features recent developments in providing tools for the diagnosis of faults or incipient faults in electric motor drives: Sensorless torque measurement, direct detection of turn-to-turn short circuits, detection of cracked or broken rotor bars, and detection of bearing deterioration.

  10. Hybrid vehicle motor alignment

    DOEpatents

    Levin, Michael Benjamin

    2001-07-03

    A rotor of an electric motor for a motor vehicle is aligned to an axis of rotation for a crankshaft of an internal combustion engine having an internal combustion engine and an electric motor. A locator is provided on the crankshaft, a piloting tool is located radially by the first locator to the crankshaft. A stator of the electric motor is aligned to a second locator provided on the piloting tool. The stator is secured to the engine block. The rotor is aligned to the crankshaft and secured thereto.

  11. A Sensory-Motor Control Model of Animal Flight Explains Why Bats Fly Differently in Light Versus Dark

    PubMed Central

    Bar, Nadav S.; Skogestad, Sigurd; Marçal, Jose M.; Ulanovsky, Nachum; Yovel, Yossi

    2015-01-01

    Animal flight requires fine motor control. However, it is unknown how flying animals rapidly transform noisy sensory information into adequate motor commands. Here we developed a sensorimotor control model that explains vertebrate flight guidance with high fidelity. This simple model accurately reconstructed complex trajectories of bats flying in the dark. The model implies that in order to apply appropriate motor commands, bats have to estimate not only the angle-to-target, as was previously assumed, but also the angular velocity (“proportional-derivative” controller). Next, we conducted experiments in which bats flew in light conditions. When using vision, bats altered their movements, reducing the flight curvature. This change was explained by the model via reduction in sensory noise under vision versus pure echolocation. These results imply a surprising link between sensory noise and movement dynamics. We propose that this sensory-motor link is fundamental to motion control in rapidly moving animals under different sensory conditions, on land, sea, or air. PMID:25629809

  12. Experimental study on multiple-pulse performance characteristics of ammonium perchlorate/aluminum powder rocket motor

    NASA Astrophysics Data System (ADS)

    Li, Yue; Hu, Chunbo; Deng, Zhe; Li, Chao; Sun, Haijun; Cai, Yupeng

    2017-04-01

    The performance characteristics of ammonium perchlorate/aluminum powder rocket motor were investigated experimentally based on a powder rocket testing system. Three-pulse experiment with one hour interval and four-pulse experiment with 15 s interval were conducted with a bi-propellant powder feed system. The experiments demonstrate the feasibility of the powder rocket for the multiple-pulse operation and the synchronization of powder feed method. The multiple-pulse performance characteristics were analyzed accordingly. It shows that the motor initiates steadily with the mass flow rate of 2.5 g/s for oxidizer powder fluidization gas and 2.0 g/s for fuel powder fluidization gas. The relative standard deviation was adopted to describe the repeatability characteristics of the pulses. The relative standard deviation of ammonium perchlorate and aluminum pistons velocity is 0.072 and 0.007, and that of oxidizer-fuel mass feed ratio is 0.052. The motor performed well with good repeatability of combustor pressure, start-up response and combustion efficiency during the multiple-pulse tests. Low frequency combustion pressure oscillations,3.6-4.2 Hz with amplitudes up to 18.7% of mean combustor pressure, were encountered. The phenomenon appeared seriously at first pulse, then alleviated at the following pulses. Further analysis of test results showed that increasing chamber pressure could ameliorate the oscillation.

  13. Pistachio supplementation attenuates motor and cognition impairments induced by cisplatin or vincristine in rats

    PubMed Central

    Golchin, Leila; Shabani, Mohammad; Harandi, Shaahin; Razavinasab, Moazamehosadat

    2015-01-01

    Background: A large number of natural products and dietary components have been evaluated as potential chemoprotective agents. In the present investigation we report the effects of treatment with the dietary antioxidant, pistachio, on cisplatin- or vincristine-induced neurotoxicity in male Wistar rats. Materials and Methods: Dietary pistachio (10%) was assessed for its neuroprotective effects through the alteration in performance of hippocampus- and cerebellum-related behaviors following chronic cisplatin (5 mg/kg) or vincristine (0.2 mg/kg) treatment in male rats. We also evaluated the effects of cisplatin, vincristine, and pistachio administration on nociception. Six behavioral tasks were used: open field, rotarod, grasping, Morris water maze (MWM), hot plate, and motor nerve conductive velocity (MNCV). Results: We showed that the exposure of adolescent rats to cisplatin or vincristine resulted in a significant decrease in explorative behaviors and memory retention. Pistachio consumption somewhat improved memory and motor abilities in cisplatin- or vincristine-treated rats, while pistachio alone did not show any significant changes in these abilities compared to saline. Cisplatin and vincristine increased the latency of response to nociception, and pistachio did not reverse this effect. Conclusion: We conclude that pistachio in the diet following anticancer drugs such as cisplatin and vincristine might have a protective effect against anticancer drug-induced disruptions in motor and cognitive function. However, further studies are needed to elucidate the exact mechanisms of this protective effect of pistachio. PMID:26015918

  14. Brownian motors in the low-energy approximation: Classification and properties

    SciTech Connect

    Rozenbaum, V. M.

    2010-04-15

    We classify Brownian motors based on the expansion of their velocity in terms of the reciprocal friction coefficient. The two main classes of motors (with dichotomic fluctuations in homogeneous force and periodic potential energy) are characterized by different analytical dependences of their mean velocity on the spatial and temporal asymmetry coefficients and by different adiabatic limits. The competition between the spatial and temporal asymmetries gives rise to stopping points. The transition through these points can be achieved by varying the asymmetry coefficients, temperature, and other motor parameters, which can be used, for example, for nanoparticle segregation. The proposed classification separates out a new type of motors based on synchronous fluctuations in symmetric potential and applied homogeneous force. As an example of this type of motors, we consider a near-surface motor whose two-dimensional motion (parallel and perpendicular to the substrate plane) results from fluctuations in external force inclined to the surface.

  15. Design Theory of a Variable Characteristic Motor Using Compound Magnetomotive Forces

    NASA Astrophysics Data System (ADS)

    Kato, Takashi; Akatsu, Kan; Shigeta, Tomoaki; Nakano, Masaki; Tsukamoto, Masahiro; Arimitsu, Minoru

    The permanent magnet synchronous motor offers the possibility of obtaining higher efficiency in a smaller motor size. However, it is difficult to vary the range of high motor efficiency because of its constant magnetomotive force (MMF) level. This paper proposes a variable characteristic motor that embodies a new concept of the compound magnetomotive forces (CMMF) motor. The motor uses a special magnet arrangement that has the MMF of components with different number of pole pairs. The application of compound current control to this motor makes it possible to vary the motor speed and torque (N-T) characteristics. This paper describes the derivation of the theoretical equations for this CMMF motor. It also presents the results of FEA and experiments conducted with the prototype motor to demonstrate the validity of the CMMF concept.

  16. Improvement in Stroke-induced Motor Dysfunction by Music-supported Therapy: A Systematic Review and Meta-analysis

    PubMed Central

    Zhang, Yingshi; Cai, Jiayi; Zhang, Yaqiong; Ren, Tianshu; Zhao, Mingyi; Zhao, Qingchun

    2016-01-01

    To conduct a meta-analysis of clinical trials that examined the effect of music-supported therapy on stroke-induced motor dysfunction, comprehensive literature searches of PubMed, Embase and the Cochrane Library from their inception to April 2016 were performed. A total of 10 studies (13 analyses, 358 subjects) were included; all had acceptable quality according to PEDro scale score. The baseline differences between the two groups were confirmed to be comparable. Compared with the control group, the standardized mean difference of 9-Hole Peg Test was 0.28 (−0.01, 0.57), 0.64 (0.31, 0.97) in Box and Block Test, 0.47 (0.08, 0.87) in Arm Paresis Score and 0.35 (−0.04, 0.75) in Action Research Arm Test for upper-limb motor function, 0.11 (−0.24, 0.46) in Berg Balance Scale score, 0.09 (−0.36, 0.54) in Fugl-Meyer Assessment score, 0.30 (−0.15, 0.74) in Wolf Motor Function Test, 0.30 (−0.15, 0.74) in Wolf Motor Function time, 0.65 (0.14, 1.16) in Stride length and 0.62 (0.01, 1.24) in Gait Velocity for total motor function, and 1.75 (0.94, 2.56) in Frontal Assessment Battery score for executive function. There was evidence of a positive effect of music-supported therapy, supporting its use for the treatment of stroke-induced motor dysfunction. This study was registered at PRESPERO (CRD42016037106). PMID:27917945

  17. Progress in the last 25 years and future perspectives in the low to high-velocity friction studies of faults; a time to shift from dry to wet experiments

    NASA Astrophysics Data System (ADS)

    Shimamoto, T.; Ma, S.; Yao, L.; Togo, T.

    2014-12-01

    High-velocity friction experiments in the last 25 years have contributed greatly to the understanding of the physical processes and mechanical properties of fault zones during seismic fault motion. But most experiments have been done at low normal stresses, under dry conditions, and at room temperature. A rationale for conducting experiments under controlled pore-pressure conditions is that specific fracture energy at a 100 MPa normal stress, extrapolated from the experimental results at low normal-stresses, is smaller than the fracture energy estimated for natural earthquakes by about one order of magnitude. Thus dry data are not consistent with earthquakes with respect to the specific fracture energy, and wet experiments may lead to a completely different framework of fault mechanics. We review nineteen existing friction apparatuses having high-velocity capabilities. Velocity regimes are conventionally classified into low velocity below 10-7 m/s, intermediate velocity between 10-7~10-4 m/s, and high velocity above 10-4 m/s. Then there are six high-velocity friction apparatuses, five intermediate to high-velocity apparatuses, and eight low to high-velocity apparatuses currently in use. Seven apparatuses can cover plate velocities on the order of 10-9 m/s to high velocities to allow studies of earthquake nucleation to dynamic rupture processes. Six apparatuses are equipped with pressure vessels and experiments with pore pressures are becoming possible. Use of Ti-Al alloy with a thermal conductivity almost as low as that of rock will open a way to expand the high-normal stress capability dramatically. We also report a rotary-shear low to high-velocity friction apparatus at IGCEA, capable of producing plate to seismic velocities (44 mm/yr to 2.1 m/s), and velocity jumps by 103 or 106 by using five electromagnetic clutches without stopping the motor. A unique feature of the apparatus is a large specimen chamber where different specimen assemblies can be installed

  18. The Role of Parents in Early Motor Intervention

    ERIC Educational Resources Information Center

    Mahoney, Gerald; Perales, Frida

    2006-01-01

    In this article we discuss the results of a motor intervention study that we conducted with young children with Down syndrome and other disabilities (Mahoney, Robinson & Fewell, 2001). Results from this study indicated that neither of the two major treatment models that are commonly used with young children with motor impairments was effective at…

  19. Assessing Gross Motor Skills of Kosovar Preschool Children

    ERIC Educational Resources Information Center

    Shala, Merita

    2009-01-01

    In the light of the new developments in preschool education in Kosovo, this study attempts to carry out an assessment of the development of gross motor skills of preschool children attending institutional education. The emphasis is on creating a set of tests to measure the motor attainments of these children by conducting assessments of the…

  20. A comparative study of velocity increment generation between the rigid body and flexible models of MMET

    SciTech Connect

    Ismail, Norilmi Amilia

    2016-02-01

    The motorized momentum exchange tether (MMET) is capable of generating useful velocity increments through spin–orbit coupling. This study presents a comparative study of the velocity increments between the rigid body and flexible models of MMET. The equations of motions of both models in the time domain are transformed into a function of true anomaly. The equations of motion are integrated, and the responses in terms of the velocity increment of the rigid body and flexible models are compared and analysed. Results show that the initial conditions, eccentricity, and flexibility of the tether have significant effects on the velocity increments of the tether.

  1. Factors influencing perceived angular velocity

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary K.; Calderone, Jack B.

    1991-01-01

    Angular velocity perception is examined for rotations both in depth and in the image plane and the influence of several object properties on this motion parameter is explored. Two major object properties are considered, namely, texture density which determines the rate of edge transitions for rotations in depth, i.e., the number of texture elements that pass an object's boundary per unit of time, and object size which determines the tangential linear velocities and 2D image velocities of texture elements for a given angular velocity. Results of experiments show that edge-transition rate biased angular velocity estimates only when edges were highly salient. Element velocities had an impact on perceived angular velocity; this bias was associated with 2D image velocity rather than 3D tangential velocity. Despite these biases judgements were most strongly determined by the true angular velocity. Sensitivity to this higher order motion parameter appeared to be good for rotations both in depth (y-axis) and parallel to the line of sight (z-axis).

  2. Hydrokinetic canal measurements: inflow velocity, wake flow velocity, and turbulence

    SciTech Connect

    Gunawan, Budi

    2014-06-11

    The dataset consist of acoustic Doppler current profiler (ADCP) velocity measurements in the wake of a 3-meter diameter vertical-axis hydrokinetic turbine deployed in Roza Canal, Yakima, WA, USA. A normalized hub-centerline wake velocity profile and two cross-section velocity contours, 10 meters and 20 meters downstream of the turbine, are presented. Mean velocities and turbulence data, measured using acoustic Doppler velocimeter (ADV) at 50 meters upstream of the turbine, are also presented. Canal dimensions and hydraulic properties, and turbine-related information are also included.

  3. Velocity dependant splash behaviour

    NASA Astrophysics Data System (ADS)

    Hamlett, C. A. E.; Shirtcliffe, N. J.; McHale, G.; Ahn, S.; Doerr, S. H.; Bryant, R.; Newton, M. I.

    2012-04-01

    Extreme soil water repellency can occur in nature via condensation of volatile organic compounds released during wildfires and can lead to increased erosion rate. Such extreme water repellent soil can be classified as superhydrophobic and shares similar chemical and topographical features to specifically designed superhydrophobic surfaces. Previous studies using high speed videography to investigate single droplet impact behaviour on artificial superhydrophobic have revealed three distinct modes of splash behaviour (rebound, pinned and fragmentation) which are dependent on the impact velocity of the droplet. In our studies, using high-speed videography, we show that such splash behaviour can be replicated on fixed 'model' water repellent soils (hydrophobic glass beads/particles). We show that the type of splash behaviour is dependent on both the size and chemical nature of the fixed particles. The particle shape also influences the splash behaviour as shown by drop impact experiments on fixed sand samples. We have also studied soil samples, as collected from the field, which shows that the type of droplet splash behaviour can lead to enhanced soil particle transport.

  4. Particle Velocity Measuring System

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Carl, James R. (Inventor)

    1998-01-01

    Method and apparatus are provided for determining the velocity of individual food particles within a liquid/solid food mixture that is cooked by an aseptic cooking method whereby the food mixture is heated as it flows through a flowline. At least one upstream and at least one downstream microwave transducer are provided to determine the minimum possible travel time of the fastest food particle through the flowline. In one embodiment, the upstream detector is not required. In another embodiment, a plurality of small dipole antenna markers are secured to a plurality of food particles to provide a plurality of signals as the markers pass the upstream and downstream transducers. The dipole antenna markers may also include a non-linear element to reradiate a harmonic frequency of a transmitter frequency. Upstream and downstream transducers include dipole antennas that are matched to the impedance of the food slurry and a signal transmission cable by various impedance matching means including unbalanced feed to the antennas.

  5. Peculiar cosmological velocities

    SciTech Connect

    Lewis, C.M.

    1990-01-01

    In the first section a gauge-invariant, variations formalism for investigating vector perturbations is set up, suitable for showing that there is no natural way that the usual scalar inflation field could give rise to vorticities. In the last two sections, a vector field A{sub {mu}} is coupled to the Einstein equations with a linearly perturbed Friedmann-Robertson-Walker (FRW) metric, constructed to generate first order vector perturbations. A working classical chaotic vector inflation is demonstrated and then quantum fluctuations of the field are used to constrain the cosmological perturbations. In particular, the vector momentum flux, T{sub 0i}, is tracked to the epoch where a radiation-dominated matter exists. Matching conditions using observational constraints of the cosmic microwave background radiation (CMBR) gives rise to a peculiar cosmological velocity of the order of 10{sup {minus}100}c. Amplification of this number, e.g., by breaking the conformal invariance of the field, could be used to generate cosmic magnetic fields using a dynamo mechanism.

  6. Advanced Motor and Motor Control Development

    DTIC Science & Technology

    1988-08-01

    dc motor with electronic controller over a wide load and speed range was demonstrated. A centrifugal pump was used as the loading mechanism and hydraulic fluid was pumped in simulation of an aircraft engine fuel pump requirement. A motor speed of 45,000 rpm was reached and a maximum output of 68.5 hp was demonstrated. The response of the system to step commands for speed change was established. Reduction of size and weight of electronic control was established as a primary future goal. The program system concept with minor rotating machine improvements is viable for

  7. Information on stepping motors

    NASA Astrophysics Data System (ADS)

    Fongarland, G.

    1982-04-01

    The principles of the stepping motors which are often used in servomechanisms are reviewed. Variable reluctance as well as permanent magnet stepping motors are considered. Their operation is explained which includes permanent rotation, starting, stopping, and resonance effects. Several application examples, drawn from problems in automation, are outlined.

  8. Stepping motor controller

    DOEpatents

    Bourret, Steven C.; Swansen, James E.

    1984-01-01

    A stepping motor is microprocessingly controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  9. Stepping motor controller

    DOEpatents

    Bourret, S.C.; Swansen, J.E.

    1982-07-02

    A stepping motor is microprocessor controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  10. High velocity impact experiment (HVIE)

    SciTech Connect

    Toor, A.; Donich, T.; Carter, P.

    1998-02-01

    The HVIE space project was conceived as a way to measure the absolute EOS for approximately 10 materials at pressures up to {approximately}30 Mb with order-of-magnitude higher accuracy than obtainable in any comparable experiment conducted on earth. The experiment configuration is such that each of the 10 materials interacts with all of the others thereby producing one-hundred independent, simultaneous EOS experiments The materials will be selected to provide critical information to weapons designers, National Ignition Facility target designers and planetary and geophysical scientists. In addition, HVIE will provide important scientific information to other communities, including the Ballistic Missile Defense Organization and the lethality and vulnerability community. The basic HVIE concept is to place two probes in counter rotating, highly elliptical orbits and collide them at high velocity (20 km/s) at 100 km altitude above the earth. The low altitude of the experiment will provide quick debris strip-out of orbit due to atmospheric drag. The preliminary conceptual evaluation of the HVIE has found no show stoppers. The design has been very easy to keep within the lift capabilities of commonly available rides to low earth orbit including the space shuttle. The cost of approximately 69 million dollars for 100 EOS experiment that will yield the much needed high accuracy, absolute measurement data is a bargain!

  11. Conducting a thermal conductivity survey

    NASA Technical Reports Server (NTRS)

    Allen, P. B.

    1985-01-01

    A physically transparent approximate theory of phonon decay rates is presented starting from a pair potential model of the interatomic forces in an insulator or semiconductor. The theory applies in the classical regime and relates the 3-phonon decay rate to the third derivative of the pair potential. Phonon dispersion relations do not need to be calculated, as sum rules relate all the needed quantities directly to the pair potential. The Brillouin zone averaged phonon lifetime turns out to involve a dimensionless measure of the anharmonicity multiplied by an effective density of states for 3-phonon decay. Results are given for rare gas and alkali halide crystals. For rare gases, the results are in good agreement with more elaborate perturbation calculations. Comparison to experimental data on phonon linewidths and thermal conductivity are made.

  12. Induction motor control

    NASA Astrophysics Data System (ADS)

    Hansen, Irving G.

    Electromechanical actuators developed to date have commonly ultilized permanent magnet (PM) synchronous motors. More recently switched reluctance (SR) motors have been advocated due to their robust characteristics. Implications of work which utilized induction motors and advanced control techniques are discussed. When induction motors are operated from an energy source capable of controlling voltages and frequencies independently, drive characteristics are obtained which are superior to either PM or SR motors. By synthesizing the machine frequency from a high-frequency carrier (nominally 20 kHz), high efficiencies, low distortion, and rapid torque response are available. At this time multiple horsepower machine drives were demonstrated, and work is on-going to develop a 20 hp average, 40 hp peak class of aerospace actuators. This effort is based upon high-frequency power distribution and management techniques developed by NASA for Space Station Freedom.

  13. Induction motor control

    NASA Technical Reports Server (NTRS)

    Hansen, Irving G.

    1990-01-01

    Electromechanical actuators developed to date have commonly utilized permanent magnet (PM) synchronous motors. More recently switched reluctance (SR) motors have been advocated due to their robust characteristics. Implications of work which utilizes induction motors and advanced control techniques are discussed. When induction motors are operated from an energy source capable of controlling voltages and frequencies independently, drive characteristics are obtained which are superior to either PM or SR motors. By synthesizing the machine frequency from a high frequency carrier (nominally 20 kHz), high efficiencies, low distortion, and rapid torque response are available. At this time multiple horsepower machine drives were demonstrated, and work is on-going to develop a 20 hp average, 40 hp peak class of aerospace actuators. This effort is based upon high frequency power distribution and management techniques developed by NASA for Space Station Freedom.

  14. Induction motor control

    NASA Technical Reports Server (NTRS)

    Hansen, Irving G.

    1990-01-01

    Electromechanical actuators developed to date have commonly ultilized permanent magnet (PM) synchronous motors. More recently switched reluctance (SR) motors have been advocated due to their robust characteristics. Implications of work which utilized induction motors and advanced control techniques are discussed. When induction motors are operated from an energy source capable of controlling voltages and frequencies independently, drive characteristics are obtained which are superior to either PM or SR motors. By synthesizing the machine frequency from a high-frequency carrier (nominally 20 kHz), high efficiencies, low distortion, and rapid torque response are available. At this time multiple horsepower machine drives were demonstrated, and work is on-going to develop a 20 hp average, 40 hp peak class of aerospace actuators. This effort is based upon high-frequency power distribution and management techniques developed by NASA for Space Station Freedom.

  15. Design, Synthesis, and Monitoring of Light-Activated Motorized Nanomachines

    NASA Astrophysics Data System (ADS)

    Chiang, Pinn-Tsong

    Our group has developed a family of single molecules termed nanocars, which are aimed at performing controllable motion on surfaces. In this work, a series of light-activated motorized nanomachines incorporated with a MHz frequency light-activated unidirectional rotary motor were designed and synthesized. We hope the light-activated motor can serve as the powering unit for the nanomachines, and perform controllable translational motion on surfaces or in solution. A series of motorized nanovehicles intended for scanning tunneling microscopy (STM) imaging were designed and synthesized. A p-carborane-wheeled motorized nanocar was synthesized and monitored by STM. Single-molecule imaging was accomplished on a Cu(111) surface. However, further manipulations did lead to motor induced lateral motion. We attributed this result to the strong molecule-surface interactions between the p-carborane-wheeled nanocar and the Cu(111) surface and possible energy transfer between the rotary motor and the Cu(111) surface. To fine-tune the molecule-surface interactions, an adamantane-wheeled motorized nanocar and a three-wheel nanoroadster were designed and synthesized. In addition, the STM substrates will be varied and different combinations of molecule-surface interactions will be studied. As a complimentary imaging method to STM, single-molecule fluorescence microscopy (SMFM) also provides single-molecule level resolution. Unlike STM experiment requires ultra-high vacuum and conductive substrate, SMFM experiment is conducted at ambient conditions and uses non-conductive substrate. This imaging method allows us to study another category of molecule-surface interactions. We plan to design a fluorescent motorized nanocar that is suitable for SMFM studies. However, both the motor and fluorophore are photochemically active molecules. In proximity, some undesired energy transfer or interference could occur. A cyanine 5- (cy5-) tagged motorized nanocar incorporated with the MHz motor was

  16. Motion of Euglena gracilis: Active fluctuations and velocity distribution

    NASA Astrophysics Data System (ADS)

    Romanczuk, P.; Romensky, M.; Scholz, D.; Lobaskin, V.; Schimansky-Geier, L.

    2015-07-01

    We study the velocity distribution of unicellular swimming algae Euglena gracilis using optical microscopy and active Brownian particle theory. To characterize a peculiar feature of the experimentally observed distribution at small velocities we use the concept of active fluctuations, which was recently proposed for the description of stochastically self-propelled particles [Romanczuk, P. and Schimansky-Geier, L., Phys. Rev. Lett. 106, 230601 (2011)]. In this concept, the fluctuating forces arise due to internal random performance of the propulsive motor. The fluctuating forces are directed in parallel to the heading direction, in which the propulsion acts. In the theory, we introduce the active motion via the depot model [Schweitzer, et al., Phys. Rev. Lett. 80(23), 5044 (1998)]. We demonstrate that the theoretical predictions based on the depot model with active fluctuations are consistent with the experimentally observed velocity distributions. In addition to the model with additive active noise, we obtain theoretical results for a constant propulsion with multiplicative noise.

  17. Development of PDC Bits for Downhole Motors

    SciTech Connect

    Karasawa, H.; Ohno, T.

    1995-01-01

    To develop polycrystalline hamond compact (PDC) bits of the full-face type which can be applied to downhole motor drilling, drilling tests for granite and two types of andesite were conducted using bits with 98.43 and 142.88 mm diameters. The bits successfully drilled these types of rock at rotary speeds from 300 to 400 rpm.

  18. Large-Scale Hybrid Motor Testing. Chapter 10

    NASA Technical Reports Server (NTRS)

    Story, George

    2006-01-01

    Hybrid rocket motors can be successfully demonstrated at a small scale virtually anywhere. There have been many suitcase sized portable test stands assembled for demonstration of hybrids. They show the safety of hybrid rockets to the audiences. These small show motors and small laboratory scale motors can give comparative burn rate data for development of different fuel/oxidizer combinations, however questions that are always asked when hybrids are mentioned for large scale applications are - how do they scale and has it been shown in a large motor? To answer those questions, large scale motor testing is required to verify the hybrid motor at its true size. The necessity to conduct large-scale hybrid rocket motor tests to validate the burn rate from the small motors to application size has been documented in several place^'^^.^. Comparison of small scale hybrid data to that of larger scale data indicates that the fuel burn rate goes down with increasing port size, even with the same oxidizer flux. This trend holds for conventional hybrid motors with forward oxidizer injection and HTPB based fuels. While the reason this is occurring would make a great paper or study or thesis, it is not thoroughly understood at this time. Potential causes include the fact that since hybrid combustion is boundary layer driven, the larger port sizes reduce the interaction (radiation, mixing and heat transfer) from the core region of the port. This chapter focuses on some of the large, prototype sized testing of hybrid motors. The largest motors tested have been AMROC s 250K-lbf thrust motor at Edwards Air Force Base and the Hybrid Propulsion Demonstration Program s 250K-lbf thrust motor at Stennis Space Center. Numerous smaller tests were performed to support the burn rate, stability and scaling concepts that went into the development of those large motors.

  19. Similarity of the Velocity Profile

    DTIC Science & Technology

    2014-10-01

    su x (with 0 constantb = ) is the empirically derived velocity scale developed by Zagarola and Smits [5] for turbulent boundary layer flow...Zagarola and Smits and others have shown that the velocity scaling factor given by Eq. 5 with sδ as the boundary layer thickness can collapse certain...and Smits , it is important to point out that the fact that the similarity length scale factor and the similarity velocity scale factor must follow

  20. Multimotor transport in a system of active and inactive kinesin-1 motors.

    PubMed

    Scharrel, Lara; Ma, Rui; Schneider, René; Jülicher, Frank; Diez, Stefan

    2014-07-15

    Long-range directional transport in cells is facilitated by microtubule-based motor proteins. One example is transport in a nerve cell, where small groups of motor proteins, such as kinesins and cytoplasmic dynein, work together to ensure the supply and clearance of cellular material along the axon. Defects in axonal transport have been linked to Alzheimer's and other neurodegenerative diseases. However, it is not known in detail how multimotor-based cargo transport is impaired if a fraction of the motors are defective. To mimic impaired multimotor transport in vitro, we performed gliding motility assays with varying fractions of active kinesin-1 motors and inactive kinesin-1 motor mutants. We found that impaired transport manifests in multiple motility regimes: 1), a fast-motility regime characterized by gliding at velocities close to the single-molecule velocity of the active motors; 2), a slow-motility regime characterized by gliding at close-to zero velocity or full stopping; and 3), a regime in which fast and slow motilities coexist. Notably, the transition from the fast to the slow regime occurred sharply at a threshold fraction of active motors. Based on single-motor parameters, we developed a stochastic model and a mean-field theoretical description that explain our experimental findings. Our results demonstrate that impaired multimotor transport mostly occurs in an either/or fashion: depending on the ratio of active to inactive motors, transport is either performed at close to full speed or is out of action.

  1. Axonal Velocity Distributions in Neural Field Equations

    PubMed Central

    Bojak, Ingo; Liley, David T. J.

    2010-01-01

    By modelling the average activity of large neuronal populations, continuum mean field models (MFMs) have become an increasingly important theoretical tool for understanding the emergent activity of cortical tissue. In order to be computationally tractable, long-range propagation of activity in MFMs is often approximated with partial differential equations (PDEs). However, PDE approximations in current use correspond to underlying axonal velocity distributions incompatible with experimental measurements. In order to rectify this deficiency, we here introduce novel propagation PDEs that give rise to smooth unimodal distributions of axonal conduction velocities. We also argue that velocities estimated from fibre diameters in slice and from latency measurements, respectively, relate quite differently to such distributions, a significant point for any phenomenological description. Our PDEs are then successfully fit to fibre diameter data from human corpus callosum and rat subcortical white matter. This allows for the first time to simulate long-range conduction in the mammalian brain with realistic, convenient PDEs. Furthermore, the obtained results suggest that the propagation of activity in rat and human differs significantly beyond mere scaling. The dynamical consequences of our new formulation are investigated in the context of a well known neural field model. On the basis of Turing instability analyses, we conclude that pattern formation is more easily initiated using our more realistic propagator. By increasing characteristic conduction velocities, a smooth transition can occur from self-sustaining bulk oscillations to travelling waves of various wavelengths, which may influence axonal growth during development. Our analytic results are also corroborated numerically using simulations on a large spatial grid. Thus we provide here a comprehensive analysis of empirically constrained activity propagation in the context of MFMs, which will allow more realistic studies

  2. Resolution of low-velocity control in golf putting differentiates professionals from amateurs.

    PubMed

    Hasegawa, Yumiko; Fujii, Keisuke; Miura, Akito; Yamamoto, Yuji

    2016-08-11

    It is difficult for humans to apply small amounts of force precisely during motor control. However, experts who have undergone extended training are thought to be able to control low-velocity movement with precision. We investigated the resolution of motor control in golf putting. A total of 10 professional and 10 high-level amateur golfers participated. Putting distances were 0.6-3.3 m, in increments of 0.3 m. We measured the impact velocity and the club-face angle at impact, and the acceleration profile of the downswing. The professionals showed significantly smaller coefficients of variation with respect to impact velocity and smaller root mean square errors in relation to acceleration profiles than did the amateurs. To examine the resolution of motor control for impact velocity, we investigated intra-participant differences in the impact velocity of the club head at two adjacent distances. We found that professionals had higher velocity precision when putting small distance intervals than did amateurs. That is, professionals had higher resolution of low-velocity control than did high-level amateurs. Our results suggest that outstanding performance at a task involves the ability to recognise small distinctions and to produce appropriate movements.

  3. Motor adaptation as a process of reoptimization.

    PubMed

    Izawa, Jun; Rane, Tushar; Donchin, Opher; Shadmehr, Reza

    2008-03-12

    Adaptation is sometimes viewed as a process in which the nervous system learns to predict and cancel effects of a novel environment, returning movements to near baseline (unperturbed) conditions. An alternate view is that cancellation is not the goal of adaptation. Rather, the goal is to maximize performance in that environment. If performance criteria are well defined, theory allows one to predict the reoptimized trajectory. For example, if velocity-dependent forces perturb the hand perpendicular to the direction of a reaching movement, the best reach plan is not a straight line but a curved path that appears to overcompensate for the forces. If this environment is stochastic (changing from trial to trial), the reoptimized plan should take into account this uncertainty, removing the overcompensation. If the stochastic environment is zero-mean, peak velocities should increase to allow for more time to approach the target. Finally, if one is reaching through a via-point, the optimum plan in a zero-mean deterministic environment is a smooth movement but in a zero-mean stochastic environment is a segmented movement. We observed all of these tendencies in how people adapt to novel environments. Therefore, motor control in a novel environment is not a process of perturbation cancellation. Rather, the process resembles reoptimization: through practice in the novel environment, we learn internal models that predict sensory consequences of motor commands. Through reward-based optimization, we use the internal model to search for a better movement plan to minimize implicit motor costs and maximize rewards.

  4. Velocity Dispersions Across Bulge Types

    SciTech Connect

    Fabricius, Maximilian; Bender, Ralf; Hopp, Ulrich; Saglia, Roberto; Drory, Niv; Fisher, David

    2010-06-08

    We present first results from a long-slit spectroscopic survey of bulge kinematics in local spiral galaxies. Our optical spectra were obtained at the Hobby-Eberly Telescope with the LRS spectrograph and have a velocity resolution of 45 km/s (sigma*), which allows us to resolve the velocity dispersions in the bulge regions of most objects in our sample. We find that the velocity dispersion profiles in morphological classical bulge galaxies are always centrally peaked while the velocity dispersion of morphologically disk-like bulges stays relatively flat towards the center--once strongly barred galaxies are discarded.

  5. Flow and heat transfer model for a rotating cryogenic motor

    SciTech Connect

    Dykhuizen, R.C.; Baca, R.G.; Bickel, T.C.

    1993-08-01

    Development of a high-temperature, superconducting, synchronous motor for large applications (>1000 HP) could offer significant electrical power savings for industrial users. Presently 60% of all electric power generated in the United States is converted by electric motors. A large part of two power is utilized by motors 1000 HP or larger. The use of high-temperature superconducting materials with critical temperatures above that of liquid nitrogen (77 K) in the field winding would reduce the losses in these motors significantly, and therefore, would have a definite impact on the electrical power usage in the US. These motors will be 1/3 to 1/2 the size of conventional motors of similar power and, thus, offer potential savings in materials and floor space. The cooling of the superconducting materials in the field windings of the rotor presents a unique application of cryogenic engineering. The rotational velocity results in significant radial pressure gradients that affect the flow distribution of the cryogen. The internal pressure fields can result in significant nonuniformities in the two-phase flow of the coolant. Due to the variable speed design, the flow distribution has the potential to change during operation. A multiphase-flow computer model of the cryogenic cooling is developed to calculate the boiling heat transfer and phase distribution of the nitrogen coolant in the motor. The model accounts for unequal phase velocities and nonuniform cooling requirements of the rotor. The unequal radial pressure gradients in the inlet and outlet headers result in a larger driving force for flow in the outer cooling channels. The effect of this must be accounted for in the design of the motor. Continuing improvements of the model will allow the investigation of the transient thermal issues associated with localized quenching of the superconducting components of the motor.

  6. Flow and heat transfer model for a rotating cryogenic motor

    NASA Astrophysics Data System (ADS)

    Dykhuizen, R. C.; Baca, R. G.; Bickel, T. C.

    1993-08-01

    Development of a high-temperature, superconducting, synchronous motor for large applications (greater than 1000 HP) could offer significant electrical power savings for industrial users. Presently 60% of all electric power generated in the United States is converted by electric motors. A large part of this power is utilized by motors 1000 HP or larger. The use of high-temperature superconducting materials with critical temperatures above that of liquid nitrogen (77 K) in the field winding would reduce the losses in these motors significantly, and therefore, would have a definite impact on the electrical power usage in the U.S. These motors will be 1/3 to 1/2 the size of conventional motors of similar power and, thus, offer potential savings in materials and floor space. The cooling of the superconducting materials in the field windings of the rotor presents a unique application of cryogenic engineering. The rotational velocity results in significant radial pressure gradients that affect the flow distribution of the cryogen. The internal pressure fields can result in significant nonuniformities in the two-phase flow of the coolant. Due to the variable speed design, the flow distribution has the potential to change during operation. A multiphase-flow computer model of the cryogenic cooling is developed to calculate the boiling heat transfer and phase distribution of the nitrogen coolant in the motor. The model accounts for unequal phase velocities and nonuniform cooling requirements of the rotor. The unequal radial pressure gradients in the inlet and outlet headers result in a larger driving force for flow in the outer cooling channels. The effect of this must be accounted for in the design of the motor. Continuing improvements of the model will allow the investigation of the transient thermal issues associated with localized quenching of the superconducting components of the motor.

  7. Motor-Cognitive Dual-Task Training in Neurologic Disorders: A Systematic Review

    PubMed Central

    Fritz, NE; Cheek, FM; Nichols-Larsen, DS

    2015-01-01

    Background and Purpose Deficits in motor-cognitive dual-tasks (e.g., walking while talking) are common in individuals with neurological conditions. This review was conducted to determine the effectiveness of motor-cognitive dual-task training (DTT) compared to usual care on mobility and cognition in individuals with neurologic disorders. Methods Databases searched were Biosis, CINAHL, ERIC, PsychInfo, EBSCO Psychological & Behavioral, PubMed, Scopus, and Web of Knowledge. Eligibility criteria were studies of adults with neurologic disorders that included DTT and outcomes of gait or balance were included. Fourteen studies met inclusion criteria. Participants were individuals with brain injury, Parkinson’s disease (PD) and Alzheimer’s disease (AD). Intervention protocols included cued walking, cognitive tasks paired with gait, balance, and strength training and virtual reality or gaming. Quality of the included trials was evaluated with a standardized rating scale of clinical relevance. Results Results show that DTT improves single-task gait velocity and stride length in PD and AD, dual-task gait velocity and stride length in PD, AD and brain injury, and may improve balance and cognition in PD and AD. The inclusion criteria limited the diagnostic groups included. Discussion and Conclusions The range of training protocols and outcome assessments in available studies limited comparison of the results across studies. Improvement of dual-task ability in individuals with neurologic disorders holds potential for improving gait, balance and cognition. Motor-cognitive dual-task deficits in individuals with neurologic disorders may be amenable to training. Video Abstract available for additional insights from the authors (See Supplemental Digital Content). PMID:26079569

  8. Wave measurements using GPS velocity signals.

    PubMed

    Doong, Dong-Jiing; Lee, Beng-Chun; Kao, Chia Chuen

    2011-01-01

    This study presents the idea of using GPS-output velocity signals to obtain wave measurement data. The application of the transformation from a velocity spectrum to a displacement spectrum in conjunction with the directional wave spectral theory are the core concepts in this study. Laboratory experiments were conducted to verify the accuracy of the inversed displacement of the surface of the sea. A GPS device was installed on a moored accelerometer buoy to verify the GPS-derived wave parameters. It was determined that loss or drifting of the GPS signal, as well as energy spikes occurring in the low frequency band led to erroneous measurements. Through the application of moving average skill and a process of frequency cut-off to the GPS output velocity, correlations between GPS-derived, and accelerometer buoy-measured significant wave heights and periods were both improved to 0.95. The GPS-derived one-dimensional and directional wave spectra were in agreement with the measurements. Despite the direction verification showing a 10° bias, this exercise still provided useful information with sufficient accuracy for a number of specific purposes. The results presented in this study indicate that using GPS output velocity is a reasonable alternative for the measurement of ocean waves.

  9. Treatment of transected peripheral nerves with artemin improved motor neuron regeneration, but did not reduce nerve injury-induced pain behaviour.

    PubMed

    Widenfalk, Johan; Wu, Weiping; Hao, Jingxia; Person, Jonas K E; Wiesenfeldt-Hallin, Zsuzsanna; Risling, Mårten

    2009-01-01

    Incomplete recovery of function and neuropathic pain are common problems after peripheral nerve injury. To develop new treatment strategies for peripheral nerve injuries we investigated whether the neurotrophic factor artemin could improve outcome after sciatic nerve injuries in rats. Artemin is a member of the glial cell line-derived neurotrophic factor (GDNF) family and exerts neuroprotective effects on sensory neurons as well as influencing behavioural thermal sensitivity. We additionally evaluated if fibrin sealant, which is sometimes used as a nerve glue, had any effects on neuropathic pain-related behaviour. After the sciatic nerve had been transected, 30 animals were randomised to one of three groups: treatment with a fibrin sealant that contained artemin in conjunction with sutures; fibrin sealant with no artemin (sham) in conjunction with sutures; or sutures alone (n=10 in each group). Motor function, sensory function, and autotomy were evaluated from 1 to 12 weeks after injury. Retrograde flourogold tracing 12 weeks after injury showed that the addition of artemin increased the number of regenerating motor neurons. However, it did not improve their performance, as measured by the Sciatic Function Index, compared with sham or suture alone. Animals treated with artemin had a non-significant increase in motor nerve conduction velocity compared with sham. However, artemin did not reverse nerve injury-induced pain behaviour such as cold or heat hypersensitivity. Fibrin sealant in itself did not ameliorate motor performance, or regeneration of motor neurons, or give rise to nerve injury-induced pain behaviour. The results indicate that artemin is of value as a treatment for peripheral nerve injuries, although the effects were limited. As the artemin high-affinity receptor GFRalpha-3 is present in Schwann cells and not in motor neurons, the effect on motor neuron axon regeneration may result from an indirect effect through Schwann cells in the injured nerve.

  10. IEMDC - In-Line Electric Motor Driven Compressor

    SciTech Connect

    Michael J. Crowley

    2004-03-31

    This report covers the fifth quarter (01/01/04 to 03/31/04) of the In-Line Electric Motor Driven Compressor (IEMDC) project. Design efforts on the IEMDC continued with compressor efforts focused on performing aerodynamic analyses. These analyses were conducted using computational fluid dynamics. Compressor efforts also entailed developing mechanical designs of components through the use of solid models and working on project deliverables. Electric motor efforts focused on the design of the magnetic bearing system, motor pressure housing, and the motor-compressor interface. The mechanical evaluation of the main interface from both the perspective of the compressor manufacturer and electric motor manufacturer indicates that an acceptable design has been achieved. All mechanical and aerodynamic design efforts have resulted in considerable progress being made towards the completion of the compressor and electric motor design and towards the successful completion of the IEMDC unit.

  11. Velocity ratio and its application to predicting velocities

    USGS Publications Warehouse

    Lee, Myung W.

    2003-01-01

    The velocity ratio of water-saturated sediment derived from the Biot-Gassmann theory depends mainly on the Biot coefficient?a property of dry rock?for consolidated sediments with porosity less than the critical porosity. With this theory, the shear moduli of dry sediments are the same as the shear moduli of water-saturated sediments. Because the velocity ratio depends on the Biot coefficient explicitly, Biot-Gassmann theory accurately predicts velocity ratios with respect to differential pressure for a given porosity. However, because the velocity ratio is weakly related to porosity, it is not appropriate to investigate the velocity ratio with respect to porosity (f). A new formulation based on the assumption that the velocity ratio is a function of (1?f)n yields a velocity ratio that depends on porosity, but not on the Biot coefficient explicitly. Unlike the Biot-Gassmann theory, the shear moduli of water-saturated sediments depend not only on the Biot coefficient but also on the pore fluid. This nonclassical behavior of the shear modulus of water-saturated sediment is speculated to be an effect of interaction between fluid and the solid matrix, resulting in softening or hardening of the rock frame and an effect of velocity dispersion owing to local fluid flow. The exponent n controls the degree of softening/hardening of the formation. Based on laboratory data measured near 1 MHz, this theory is extended to include the effect of differential pressure on the velocity ratio by making n a function of differential pressure and consolidation. However, the velocity dispersion and anisotropy are not included in the formulation.

  12. Sodium Velocity Maps on Mercury

    NASA Technical Reports Server (NTRS)

    Potter, A. E.; Killen, R. M.

    2011-01-01

    The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

  13. High Velocity Clouds

    NASA Technical Reports Server (NTRS)

    Wolfire, M. G.; McKee, C. F.; Hollenbach, D. J.; Tielens, A. G. G. M.; Morrison, David (Technical Monitor)

    1994-01-01

    We calculate the thermal equilibrium gas temperature of high velocity clouds (HVCs) in the Galactic Halo. Our method accounts for the photoelectric heating from small grains and PAHs, and includes a detailed treatment of the ionization rates and heating due to the soft X-ray background and due to cosmic rays. Phase diagrams (thermal pressure P versus gas density n) are presented for gas with a range of dust/gas ratios (D/G) and a range of metallicities (Z). Variations in D/G affect mainly the photoelectric heating rate, while variations in Z affect both the photoelectric heating and gas cooling. Curves are shown for D/G = 1 (local value) to D/G less than approx. equal to 0.005 and for Z=1 (local value) to Z= 0.005. We find that a two phase medium (CNM + WNM) can be in pressure equilibrium with a hot (T approximately 1-2 x 10(exp 6) K) halo within a range of permitted pressures, P(sup min) to P(sup max). We take halo parameters consistent with observed properties of the soft X-ray background. In general, both P(sup min) and P(sup max) decrease with lower D/G due to a drop in photoelectric heating from grains, while. P(sup min) and P(sup max) increase with lower Z due to a drop in gas coolants. We demonstrate that successful two phase models can be constructed with pressure in the range 10(exp 3) less than approximately equal to P/k less than approximately equal to 10(exp 4) K cm(exp -3) consistent with the thermal pressure in the Galactic disk. In addition, using the observed relation between CNM density and distance in HVCs, (n = 75/fDkpc cm(exp -3); Wakker & Schwarz 1991, AA, 250, 484) we show that our pressure curves constrain the allowed range of HVC heights to be between 0.3 - 16 kpc.

  14. ISRO's solid rocket motors

    NASA Astrophysics Data System (ADS)

    Nagappa, R.; Kurup, M. R.; Muthunayagam, A. E.

    1989-08-01

    Solid rocket motors have been the mainstay of ISRO's sounding rockets and the first generation satellite launch vehicles. For the new launch vehicle under development also, the solid rocket motors contribute significantly to the vehicle's total propulsive power. The rocket motors in use and under development have been developed for a variety of applications and range in size from 30 mm dia employing 450 g of solid propellant—employed for providing a spin to the apogee motors—to the giant 2.8 m dia motor employing nearly 130 tonnes of solid propellant. The initial development, undertaken in 1967 was of small calibre motor of 75 mm dia using a double base charge. The development was essentially to understand the technological elements. Extruded aluminium tubes were used as a rocket motor casing. The fore and aft closures were machined from aluminium rods. The grain was a seven-pointed star with an enlargement of the port at the aft end and was charged into the chamber using a polyester resin system. The nozzle was a metallic heat sink type with graphite throat insert. The motor was ignited with a black powder charge and fired for 2.0 s. Subsequent to this, further developmental activities were undertaken using PVC plastisol based propellants. A class of sounding rockets ranging from 125 to 560 mm calibre were realized. These rocket motors employed improved designs and had delivered lsp ranging from 2060 to 2256 Ns/kg. Case bonding could not be adopted due to the higher cure temperatures of the plastisol propellants but improvements were made in the grain charging techniques and in the design of the igniters and the nozzle. Ablative nozzles based on asbestos phenolic and silica phenolic with graphite inserts were used. For the larger calibre rocket motors, the lsp could be improved by metallic additives. In the early 1970s designs were evolved for larger and more efficient motors. A series of 4 motors for the country's first satellite launch vehicle SLV-3 were

  15. Generalised cognitive motor interference in multiple sclerosis.

    PubMed

    Learmonth, Y C; Pilutti, L A; Motl, R W

    2015-06-01

    Researchers have examined cognitive motor interference (CMI) for lower extremity function in MS, but have not examined this in the upper extremity. This study examined CMI for both lower and upper extremity motor tasks in persons with MS and without MS. Eighty-two persons walked on a GAITRite electronic walkway (velocity) and performed the nine-hole peg test (NHPT, seconds) without (single task) and with a cognitive challenge (dual task). The data were analysed with mixed-factor ANOVA and Pearson correlations. When comparing MS and controls, there were statistical significant and exceptionally large Task main effects on gait velocity (ηp(2)=.41; F1,60=55.78; p<.005) and NHPT performance (ηp(2)=.62; F1,60=127.8; p<.005). When considering disability status among those with MS, there were statistically significant and large Task main effects on velocity (ηp(2)=.38; F1,60=37.3; p<.005) and NHPT test (ηp(2)=.62; F1,60=95.7; p<.005). The dual task cost of walking and performing the NHPT were significantly correlated in the entire sample, those with MS and controls, and in those with MS who had mild, moderate, and severe disability (all |r|>.450). CMI occurs in both the lower and upper extremities, and is comparable between persons with and without MS and across MS disability level.

  16. Motor Priming in Neurorehabilitation

    PubMed Central

    Stoykov, Mary Ellen; Madhavan, Sangeetha

    2014-01-01

    Priming is a type of implicit learning wherein a stimulus prompts a change in behavior. Priming has been long studied in the field of psychology. More recently, rehabilitation researchers have studied motor priming as a possible way to facilitate motor learning. For example, priming of the motor cortex is associated with changes in neuroplasticity that are associated with improvements in motor performance. Of the numerous motor priming paradigms under investigation, only a few are practical for the current clinical environment, and the optimal priming modalities for specific clinical presentations are not known. Accordingly, developing an understanding of the various types of motor priming paradigms and their underlying neural mechanisms is an important step for therapists in neurorehabilitation. Most importantly, an understanding of the methods and their underlying mechanisms is essential for optimizing rehabilitation outcomes. The future of neurorehabilitation is likely to include these priming methods, which are delivered prior to or in conjunction with primary neurorehabilitation therapies. In this Special Interest article we discuss those priming paradigms that are supported by the greatest amount of evidence including: (i) stimulation-based priming, (ii) motor imagery and action observation, (iii) sensory priming, (iv) movement-based priming, and (v) pharmacological priming. PMID:25415551

  17. How to make electrodiagnosis of carpal tunnel syndrome with normal distal conductions?

    PubMed

    Lee, Wei-Ju; Liao, Yi-Chu; Wei, Shiew-Jue; Tsai, Chi-Wei; Chang, Ming-Hong

    2011-02-01

    The purpose of this study is to investigate which electrodiagnostic techniques are better in clinically diagnosed patients with carpal tunnel syndrome (CTS) and patients with CTS with normal distal conduction study. A total of 230 clinically diagnosed patients with CTS and 100 normal control subjects were enrolled. All subjects were evaluated by eight electrodiagnostic techniques, including conventional conduction studies: median distal sensory latency and distal motor latency; short distance conduction studies across wrist, including wrist-palm sensory conduction time and wrist-palm motor conduction velocity; comparison of median sensory conduction across the wrist with radial or ulnar nerves in the same limb (median-radial sensory latency difference [M-R] or median-ulnar sensory latency difference [M-U]); and comparison of median wrist-palm and palm-index conduction, including distoproximal conduction time difference and distoproximal conduction time ratio. Normal limits were derived by calculating the mean ± 2 standard deviations from the data of the controls. The sensitivity, specificity, positive predictive value, negative predictive value, and the area under the receiver operating characteristic curve with 95% confidence interval of each test were calculated. In clinically diagnosed patients with CTS, M-R is the best diagnostic technique with significant difference in area under the receiver operating characteristic curve (0.912) compared with other tests except that of M-U. The sensitivity, specificity, positive predictive value, and negative predictive value of M-R were 84.3%, 98%, 99%, and 73.1%, respectively. Further evaluation of patients with CTS with normal distal latencies also revealed the best diagnostic value of M-R and M-U with significance to other tests in area under the receiver operating characteristic curve. In clinical practice, after conventional median distal sensory latency and distal motor latency studies, the authors suggest performing

  18. Motor evoked potentials enable differentiation between motor and sensory branches of peripheral nerves in animal experiments.

    PubMed

    Turkof, Edvin; Jurasch, Nikita; Knolle, Erik; Schwendenwein, Ilse; Habib, Danja; Unger, Ewald; Reichel, Martin; Losert, Udo

    2006-10-01

    Differentiation between motor and sensory fascicles is frequently necessary in reconstructive peripheral nerve surgery. The goal of this experimental study was to verify if centrally motor evoked potentials (MEP) could be implemented to differentiate sensory from motor fascicles, despite the well-known intermingling between nerve fascicles along their course to their distant periphery. This new procedure would enable surgeons to use MEP for placing nerve grafts at corresponding fascicles in the proximal and distal stumps without the need to use time-consuming staining. In ten sheep, both ulnar nerves were exposed at the terminal bifurcation between the last sensory and motor branch. Animals were then relaxed to avoid volume conduction. On central stimulation, the evoked nerve compound action potentials were simultaneously recorded from both terminal branches. In all cases, neurogenic motor nerve action potentials were recorded only from the terminal motor branch. The conclusion was that MEPs can be used for intraoperative differentiation between sensory and motor nerves. Further studies are necessary to develop this method for in situ measurements on intact nerve trunks.

  19. Suppression of proprioceptor--motor neuron interactions by proprioceptors in crayfish claw.

    PubMed

    Lindsey, B G

    1982-11-04

    Crayfish claw proprioceptors and slow closer exciter and opener inhibitor motor neurons were monitored simultaneously during imposed claw displacements. With increasing displacement velocity and decreasing joint angle, the activity of closing sensitive receptors increased, while dynamic-static opening sensitive receptor activity decreased during claw closing. Motor neuron activity evoked by claw opening varied inversely as a function of preceding closing velocity, and directly with preceding pause duration at the closed position. This dependence on closing history cannot be accounted for by changes in opening sensitive receptor activity. Data demonstrate that closing sensitive receptors can suppress excitatory interactions between claw proprioceptors and motor neurons.

  20. Development of Erosive Burning Models for CFD Predictions of Solid Rocket Motor Internal Environments

    NASA Technical Reports Server (NTRS)

    Wang, Qun-Zhen

    2003-01-01

    Four erosive burning models, equations (11) to (14). are developed in this work by using a power law relationship to correlate (1) the erosive burning ratio and the local velocity gradient at propellant surfaces; (2) the erosive burning ratio and the velocity gradient divided by centerline velocity; (3) the erosive burning difference and the local velocity gradient at propellant surfaces; and (4) the erosive burning difference and the velocity gradient divided by centerline velocity. These models depend on the local velocity gradient at the propellant surface (or the velocity gradient divided by centerline velocity) only and, unlike other empirical models, are independent of the motor size. It was argued that, since the erosive burning is a local phenomenon occurring near the surface of the solid propellant, the erosive burning ratio should be independent of the bore diameter if it is correlated with some local flow parameters such as the velocity gradient at the propellant surface. This seems to be true considering the good results obtained by applying these models, which are developed from the small size 5 inch CP tandem motor testing, to CFD simulations of much bigger motors.

  1. Multi-Velocity Component LDV

    NASA Technical Reports Server (NTRS)

    Johnson, Dennis A. (Inventor)

    1996-01-01

    A laser doppler velocimeter uses frequency shifting of a laser beam to provide signal information for each velocity component. A composite electrical signal generated by a light detector is digitized and a processor produces a discrete Fourier transform based on the digitized electrical signal. The transform includes two peak frequencies corresponding to the two velocity components.

  2. Instantaneous Velocity Using Photogate Timers

    ERIC Educational Resources Information Center

    Wolbeck, John

    2010-01-01

    Photogate timers are commonly used in physics laboratories to determine the velocity of a passing object. In this application a card attached to a moving object breaks the beam of the photogate timer providing the time for the card to pass. The length L of the passing card can then be divided by this time to yield the average velocity (or speed)…

  3. Creating biomolecular motors based on dynein and actin-binding proteins

    NASA Astrophysics Data System (ADS)

    Furuta, Akane; Amino, Misako; Yoshio, Maki; Oiwa, Kazuhiro; Kojima, Hiroaki; Furuta, Ken'ya

    2016-11-01

    Biomolecular motors such as myosin, kinesin and dynein are protein machines that can drive directional movement along cytoskeletal tracks and have the potential to be used as molecule-sized actuators. Although control of the velocity and directionality of biomolecular motors has been achieved, the design and construction of novel biomolecular motors remains a challenge. Here we show that naturally occurring protein building blocks from different cytoskeletal systems can be combined to create a new series of biomolecular motors. We show that the hybrid motors—combinations of a motor core derived from the microtubule-based dynein motor and non-motor actin-binding proteins—robustly drive the sliding movement of an actin filament. Furthermore, the direction of actin movement can be reversed by simply changing the geometric arrangement of these building blocks. Our synthetic strategy provides an approach to fabricating biomolecular machines that work along artificial tracks at nanoscale dimensions.

  4. Transverse Velocity Shifts in Protostellar Jets: Rotation or Velocity Asymmetries?

    NASA Astrophysics Data System (ADS)

    De Colle, Fabio; Cerqueira, Adriano H.; Riera, Angels

    2016-12-01

    Observations of several protostellar jets show systematic differences in radial velocity transverse to the jet propagation direction that have been interpreted as evidence of rotation in the jets. In this paper we discuss the origin of these velocity shifts, and show that they could originate from rotation in the flow, or from side-to-side asymmetries in the shock velocity, which could be due to asymmetries in the jet ejection velocity/density or in the ambient medium. For typical poloidal jet velocities (˜100-200 km s-1), an asymmetry ≳10% can produce velocity shifts comparable to those observed. We also present three-dimensional numerical simulations of rotating, precessing, and asymmetric jets, and show that, even though for a given jet there is a clear degeneracy between these effects, a statistical analysis of jets with different inclination angles can help to distinguish between the alternative origins of transverse velocity shifts (TVSs). Our analysis indicates that side-to-side velocitiy asymmetries could represent an important contribution to TVSs, being the most important contributor for large jet inclination angles (with respect the the plane of the sky), and cannot be neglected when interpreting the observations.

  5. Note: Cryogenic heat switch with stepper motor actuator

    SciTech Connect

    Melcher, B. S. Timbie, P. T.

    2015-12-15

    A mechanical cryogenic heat switch has been developed using a commercially available stepper motor and control electronics. The motor requires 4 leads, each carrying a maximum, pulsed current of 0.5 A. With slight modifications of the stepper motor, the switch functions reliably in vacuum at temperatures between 300 K and 4 K. The switch generates a clamping force of 262 N at room temperature. At 4 K it achieves an “on state” thermal conductance of 5.04 mW/K and no conductance in the “off state.” The switch is optimized for cycling an adiabatic demagnetization refrigerator.

  6. Note: Cryogenic heat switch with stepper motor actuator

    NASA Astrophysics Data System (ADS)

    Melcher, B. S.; Timbie, P. T.

    2015-12-01

    A mechanical cryogenic heat switch has been developed using a commercially available stepper motor and control electronics. The motor requires 4 leads, each carrying a maximum, pulsed current of 0.5 A. With slight modifications of the stepper motor, the switch functions reliably in vacuum at temperatures between 300 K and 4 K. The switch generates a clamping force of 262 N at room temperature. At 4 K it achieves an "on state" thermal conductance of 5.04 mW/K and no conductance in the "off state." The switch is optimized for cycling an adiabatic demagnetization refrigerator.

  7. Control of Stepping Velocity in the Stick Insect Carausius morosus

    PubMed Central

    Gruhn, Matthias; von Uckermann, Géraldine; Westmark, Sandra; Wosnitza, Anne; Büschges, Ansgar; Borgmann, Anke

    2009-01-01

    We performed electrophysiological and behavioral experiments in single-leg preparations and intact animals of the stick insect Carausius morosus to understand mechanisms underlying the control of walking speed. At the level of the single leg, we found no significant correlation between stepping velocity and spike frequency of motor neurons (MNs) other than the previously shown modification in flexor (stance) MN activity. However, pauses between stance and swing motoneuron activity at the transition from stance to swing phase and stepping velocity are correlated. Pauses become shorter with increasing speed and completely disappear during fast stepping sequences. By means of extra- and intracellular recordings in single-leg stick insect preparations we found no systematic relationship between the velocity of a stepping front leg and the motoneuronal activity in the ipsi- or contralateral mesothoracic protractor and retractor, as well as flexor and extensor MNs. The observations on the lack of coordination of stepping velocity between legs in single-leg preparations were confirmed in behavioral experiments with intact stick insects tethered above a slippery surface, thereby effectively removing mechanical coupling through the ground. In this situation, there were again no systematic correlations between the stepping velocities of different legs, despite the finding that an increase in stepping velocity in a single front leg is correlated with a general increase in nerve activity in all connectives between the subesophageal and all thoracic ganglia. However, when the tethered animal increased walking speed due to a short tactile stimulus, provoking an escape-like response, stepping velocities of ipsilateral legs were found to be correlated for several steps. These results indicate that there is no permanent coordination of stepping velocities between legs, but that such coordination can be activated under certain circumstances. PMID:19535483

  8. System and method for motor parameter estimation

    DOEpatents

    Luhrs, Bin; Yan, Ting

    2014-03-18

    A system and method for determining unknown values of certain motor parameters includes a motor input device connectable to an electric motor having associated therewith values for known motor parameters and an unknown value of at least one motor parameter. The motor input device includes a processing unit that receives a first input from the electric motor comprising values for the known motor parameters for the electric motor and receive a second input comprising motor data on a plurality of reference motors, including values for motor parameters corresponding to the known motor parameters of the electric motor and values for motor parameters corresponding to the at least one unknown motor parameter value of the electric motor. The processor determines the unknown value of the at least one motor parameter from the first input and the second input and determines a motor management strategy for the electric motor based thereon.

  9. Advanced motor and motor control development

    NASA Astrophysics Data System (ADS)

    Wuertz, Kenneth L.; Beauchamp, Edward D.

    1988-08-01

    The capability of operating a high speed permanent magnet brushless dc motor with electronic controller over a wide load and speed range was demonstrated. A centrifugal pump was used as the loading mechanism and hydraulic fluid was pumped in simulation of an aircraft engine fuel pump requirement. A motor speed of 45,000 rpm was reached and a maximum output of 68.5 hp was demonstrated. The response of the system to step commands for speed change was established. Reduction of size and weight of electronic control was established as a primary future goal. The program system concept with minor rotating machine improvements is viable for high speed drive applications up to 100-hp level.

  10. Report on Toyota Prius Motor Thermal Management

    SciTech Connect

    Hsu, J.S.

    2005-02-11

    In the current hybrid vehicle market, the Toyota Prius drive system is considered the leader in electrical, mechanical, and manufacturing innovations. It is a significant accomplishment that Toyota is able to manufacture and sell the vehicle for a profit. The Toyota Prius traction motor design approach for reducing manufacturing costs and the motor s torque capability have been studied and tested. The findings were presented in two previous Oak Ridge National Laboratory (ORNL) reports. The conclusions from this report reveal, through temperature rise tests, that the 2004 Toyota Prius (THSII) motor is applicable only for use in a hybrid automobile. It would be significantly undersized if used in a fuel cell vehicle application. The power rating of the Prius motor is limited by the permissible temperature rise of the motor winding (170 C) and the motor cooling oil (158 C). The continuous ratings at base speed (1200 rpm) with different coolant temperatures are projected from test data at 900 rpm. They are approximately 15 kW with 105 C coolant and 21 kW with 35 C coolant. These continuous ratings are much lower than the 30 kW specified as a technical motor target of the U.S. Department of Energy FreedomCAR Program. All tests were conducted at about 24 C ambient temperature. The load angle of each torque adjustment was monitored to prevent a sudden stop of the motor if the peak torque were exceeded, as indicated by the load angle in the region greater than 90 electrical degrees. For peak power with 400 Nm torque at 1200 rpm, the permissible running time depends upon the initial winding temperature condition. The projected rate of winding temperature rise is approximately 2.1 C/sec. The cooling-oil temperature does not change much during short peak power operation. For light and medium load situations, the efficiency varies from 80% to above 90%, and the power factor varies from 70% to above 90%, depending on the load and speed. When the motor is loaded heavily near the

  11. Motor Vehicle Safety

    MedlinePlus

    ... these crashes is one part of motor vehicle safety. Here are some things you can do to ... speed or drive aggressively Don't drive impaired Safety also involves being aware of others. Share the ...

  12. Booster separation motor

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The design, development, fabrication, testing, evaluation and flight qualification of the space shuttle booster separation motor is discussed. Delivery of flight hardware to support the research and development flights of the space shuttle is discussed.

  13. MotorWeek

    ScienceCinema

    None

    2016-07-12

    In 2008, PBS's MotorWeek, television's original automotive magazine, visited Argonne's Transportation Technology R&D Center "to learn what it really takes to make clean power sources a viable reality."

  14. Molecular Motors from DNA

    NASA Astrophysics Data System (ADS)

    Turberfield, Andrew

    2013-03-01

    DNA is a wonderful material for nanoscale construction: its self-assembly can be programmed by making use of its information-carrying capability and its hybridization or hydrolysis can be used as to provide energy for synthetic molecular machinery. With DNA it is possible to design and build three-dimensional scaffolds, to attach molecular components to them with sub-nanometre precision-and then to make them move. I shall describe our work on autonomous, biomimetic molecular motors powered by chemical fuels and the use of synthetic molecular machinery to control covalent chemical synthesis. I shall demonstrate bipedal motors whose operation depends on the coordination of the chemomechanical cycles of two separate catalytic centres and burnt bridges motors that can be programmed to navigate networks of tracks. I shall also discuss the use of kinesin motor proteins to power synthetic devices.

  15. MotorWeek

    SciTech Connect

    2009-01-01

    In 2008, PBS's MotorWeek, television's original automotive magazine, visited Argonne's Transportation Technology R&D Center "to learn what it really takes to make clean power sources a viable reality."

  16. Piezoelectric Rotary Tube Motor

    NASA Technical Reports Server (NTRS)

    Fisher, Charles D.; Badescu, Mircea; Braun, David F.; Culhane, Robert

    2011-01-01

    A custom rotary SQUIGGLE(Registered TradeMark) motor has been developed that sets new benchmarks for small motor size, high position resolution, and high torque without gear reduction. Its capabilities cannot be achieved with conventional electromagnetic motors. It consists of piezoelectric plates mounted on a square flexible tube. The plates are actuated via voltage waveforms 90 out of phase at the resonant frequency of the device to create rotary motion. The motors were incorporated into a two-axis postioner that was designed for fiber-fed spectroscopy for ground-based and space-based projects. The positioner enables large-scale celestial object surveys to take place in a practical amount of time.

  17. Proposed model for the flagellar rotary motor.

    PubMed

    Mitsui, Toshio; Ohshima, Hiroyuki

    2005-11-25

    Flagellated bacteria swim by rotating helical filaments driven by motors embedded in the cell wall and cytoplasmic membrane. A model is proposed to explain the mechanism of the motor. The protons passing through the channels induce a strong electric field in Mot molecules. This field originates an impulse force to cause the flagellar rotation if the following conditions are fulfilled: (a) Mot molecules have a spontaneous electric polarization. (b) The lipid bilayers are viscoelastic. (c) There is a delay of deformation in response to stress in Mot molecules. The conclusions driven from the model are in agreement with the following experimental observations, denoting the flagellar rotation velocity as omega. (1) The torque is practically constant independent of omega from 0 to a critical value omega(cr) and then decreases sharply. (2) When omega is smaller than omega(cr), the torque varies little with temperature. (3) The critical velocity omega(cr) shifts to lower speed at lower temperatures. (4) Where omega is larger than omega(cr), declining of the torque steepens at lower temperatures. (5) When omega is smaller than omega(cr), one revolution of the flagellar rotation consists of a constant number of steps. (6) When omega is smaller than omega(cr), omega is proportional to the transmembrane potential difference. (7) The stator produces constant torque even when the stator is rotated relative to the rotor by external forces. (8) How the flagellar rotation velocity changes when the direction of the proton passage is reversed. (9) The motor has a switch that reverses the sense of the flagelllar rotation with the same absolute value of torque.

  18. High Power Density Motors

    NASA Technical Reports Server (NTRS)

    Kascak, Daniel J.

    2004-01-01

    With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it

  19. Psychological performance in relation to central and peripheral nerve conduction in workers exposed to lead, zinc, and copper

    SciTech Connect

    Araki, S.; Yokoyama, K.; Aono, H.; Murata, K.

    1986-01-01

    Psychological performance was examined in relation to central and peripheral nerve conduction by means of the Wechsler Adult Intelligence Scale test, short-latency somatosensory-evoked potential (SSEP), and median nerve conduction velocity in 19 male gun-metal foundry workers exposed to lead, zinc, and copper. (Their blood lead concentrations--ie, 16-64 micrograms/dl with a mean of 42--and plasma zinc and copper concentrations were significantly higher than those of control subjects). In these workers, the score of picture completion (psychological performance) was significantly low; indicators of lead absorption, but no indicators of zinc and copper absorption, were significantly correlated with this score. The score of picture completion was significantly correlated with the N11-N13 latency of SSEP (conduction time in the spinobulbar region) in the workers; their N11-N13 latency, together with the N9 and N9-N11 latencies, was significantly prolonged and was significantly correlated with indicators of lead absorption. Furthermore, their maximal motor and sensory conduction velocities of the median nerve were significantly slowed. It is concluded that both psychological performance and central and peripheral nerve conduction may be impaired in lead-exposed workers with BPb's below approximately 60 micrograms/dl.

  20. Design and performance testing of an ultrasonic linear motor with dual piezoelectric actuators.

    PubMed

    Smithmaitrie, Pruittikorn; Suybangdum, Panumas; Laoratanakul, Pitak; Muensit, Nantakan

    2012-05-01

    In this work, design and performance testing of an ultrasonic linear motor with dual piezoelectric actuator patches are studied. The motor system consists of a linear stator, a pre-load weight, and two piezoelectric actuator patches. The piezoelectric actuators are bonded with the linear elastic stator at specific locations. The stator generates propagating waves when the piezoelectric actuators are subjected to harmonic excitations. Vibration characteristics of the linear stator are analyzed and compared with finite element and experimental results. The analytical, finite element, and experimental results show agreement. In the experiments, performance of the ultrasonic linear motor is tested. Relationships between velocity and pre-load weight, velocity and applied voltage, driving force and applied voltage, and velocity and driving force are reported. The design of the dual piezoelectric actuators yields a simpler structure with a smaller number of actuators and lower stator stiffness compared with a conventional design of an ultrasonic linear motor with fully laminated piezoelectric actuators.

  1. Rocket Motor Microphone Investigation

    NASA Technical Reports Server (NTRS)

    Pilkey, Debbie; Herrera, Eric; Gee, Kent L.; Giraud, Jerom H.; Young, Devin J.

    2010-01-01

    At ATK's facility in Utah, large full-scale solid rocket motors are tested. The largest is a five-segment version of the reusable solid rocket motor, which is for use on the Ares I launch vehicle. As a continuous improvement project, ATK and BYU investigated the use of microphones on these static tests, the vibration and temperature to which the instruments are subjected, and in particular the use of vent tubes and the effects these vents have at low frequencies.

  2. Motor Energy Conservation Measures

    SciTech Connect

    Ian Metzger, Jesse Dean

    2010-12-31

    This software requires inputs of simple motor inventory information and calculates the energy and cost benefits of various retrofit opportunities. This tool includes energy conservation measures for: High Efficiency Motor retrofit and Cogged V-belts retrofit. This tool calculates energy savings, demand reduction, cost savings, and building life cycle costs including: simple payback, discounted payback, net-present value, and savings to investment ratio. In addition this tool also displays the environmental benefits of a project.

  3. Maintaining Motor Skill Performance

    DTIC Science & Technology

    1982-06-18

    trials eacb--ac--yIecon- ,, :;. - taed p- --d-t-trias,--P-t- rilk --r. expermenter-difie-d- ovementu con- strained by the stop. The distance between...processing in motor control-i ... and -laIg- e-rr--’- cae -clrsj--98 I Y. ag.L., K. A., & D5oWe-l, M. R. Serial-position effects in motor short-! term

  4. Development Motor-8

    NASA Technical Reports Server (NTRS)

    1980-01-01

    One of the key tests in the effort to return the Space Shuttle to flight following the Challenger accident was testing the development Motor-8 (DM-8). The 126-foot long, 1.2-million-pound motor, designated DM-8, underwent a full-duration horizontal test firing for two minutes at the Thiokol test facility in Utah. It was fitted with more than 500 instruments to measure such things as acceleration, pressure, deflection thrust, strain, temperature, and electrical properties.

  5. A Case of Acute Motor Axonal Neuropathy Mimicking Brain Death and Review of the Literature.

    PubMed

    Ravikumar, Sandhya; Poysophon, Poysophon; Poblete, Roy; Kim-Tenser, May

    2016-01-01

    We describe a case report of fulminant Guillain-Barré syndrome (GBS) mimicking brain death. A previously healthy 60-year-old male was admitted to the neurointensive care unit after developing rapidly progressive weakness and respiratory failure. On presentation, the patient was found to have absent brainstem and spinal cord reflexes resembling that of brain death. Acute motor axonal neuropathy, a subtype of GBS, was diagnosed by cerebrospinal fluid and nerve conduction velocity testing. An electroencephalogram showed that the patient had normal, appropriately reactive brain function. Transcranial Doppler (TCD) ultrasound showed appropriate blood flow to the brain. GBS rarely presents with weakness so severe as to mimic brain death. This article provides a review of similar literature. This case demonstrates the importance of performing a proper brain death examination, which includes evaluation for irreversible cerebral injury, exclusion of any confounding conditions, and performance of tests such as electroencephalography and TCDs when uncertainty exists about the reliability of the clinical exam.

  6. Design and Evaluation of an Actuated Exoskeleton for Examining Motor Control in Stroke Thumb

    PubMed Central

    Wang, Furui; Jones, Christopher L.; Shastri, Milind; Qian, Kai; Kamper, Derek G.; Sarkar, Nilanjan

    2016-01-01

    Chronic hand impairment is common following stroke. This paper presents an actuated thumb exoskeleton (ATX) to facilitate research in examining motor control and hand rehabilitation. The ATX presented in this work aims to provide independent bi-directional actuation in each of the 5 degrees-of-freedom (DOF) of the thumb using a novel flexible shaft based mechanism that has 5 active DOF and 3 passive DOF. A prototype has been built and experiments have been conducted to measure the allowable workspace at the thumb and evaluate the kinematic and kinetic performance of the ATX. The experimental results show that the ATX is able to provide individual actuation at all 5 thumb joints with high joint velocity and torque capacities. Further improvement and future work are discussed. PMID:27672232

  7. A locus for axonal motor-sensory neuropathy with deafness and mental retardation maps to Xq26-q27

    SciTech Connect

    Priest, J.M.; Nouri, N.; Keats, B.J.B.

    1994-09-01

    Twenty-two DNA markers spanning the X chromosome have been analyzed for linkage to the locus causing an unusual form of X-linked recessive hereditary motor and sensory neuropathy in a Pennsylvania family of Italian ancestry. This 3 generation family which was originally reported by Cowchock includes 7 affected males, 3 obligate carrier females, and 4 unaffected males. Males are severely affected at birth or within the first few years of life with areflexia, slowly progressive axonal atrophy, and absence of large myelinated fibers, and they all develop pes cavus and hammer toes. Five of the 7 affected males show associated deafness and 3 of these 5 individuals also presented with mental retardation or social developmental delay. Motor nerve conduction velocities in affected males are normal to mildly delayed and sensory conduction velocities are markedly abnormal. Heterozygous females are asymptomatic. Close linkage to the Xg blood group locus (Xp22) was previously excluded in this family while weak linkage of the disease gene to DXYS1 (Xq13-q21) was suggested. The current study excludes the short arm and the proximal long arm of the X chromosome. Haplotype analysis of markers on the long arm demonstrates that HPRT is a proximal flanking marker and that the disease gene is closely linked to the marker DXS984. Further microsatellite markers are being studied in order to refine the region of the distal long arm of the X chromosome containing the gene causing the motor-sensory neuropathy in this family. This is the first such gene assigned to the distal region of Xq.

  8. Master equation approach for a cross-bridge power-stroke model with a finite number of motors.

    PubMed

    Ma, Rui; Li, Ming; Ou-Yang, Zhong-Can; Shu, Yao-Gen

    2013-05-01

    The cross-bridge power-stroke model has been widely used to describe the motion of large motor assemblies connected to a common rigid filament. In this paper, we go beyond the original velocity-ensemble approach and propose a master equation approach to account for the cooperative motion of a finite number of motors based on the cross-bridge model. By studying the force-velocity relationship for motors with strain-independent detachment rate, we show the convergence of our approach to the velocity-ensemble approach in the limit of large motor numbers. In the case that the detachment rate of motors is strain dependent, based on two assumptions for the strain distribution among motors, we show the occurrence of the bimodal distribution of the number of motors bound to the filament. This provides a new perspective to look at the instability of a multimotor system, which is essential for all the experimentally observed complex motions displayed by a group of motors, such as hysteresis, bidirectional motion, and spontaneous oscillation. By comparing the velocities calculated using the two assumptions with the stochastic simulation, it suggests that the coupling between motors via the common connection to the filament might facilitate the fast movement of filaments at small loading forces.

  9. Electric vehicle motors and controllers

    NASA Technical Reports Server (NTRS)

    Secunde, R. R.

    1981-01-01

    Improved and advanced components being developed include electronically commutated permanent magnet motors of both drum and disk configuration, an unconventional brush commutated motor, and ac induction motors and various controllers. Test results on developmental motors, controllers, and combinations thereof indicate that efficiencies of 90% and higher for individual components, and 80% to 90% for motor/controller combinations can be obtained at rated power. The simplicity of the developmental motors and the potential for ultimately low cost electronics indicate that one or more of these approaches to electric vehicle propulsion may eventually displace presently used controllers and brush commutated dc motors.

  10. Observed Magnetic Island Rotation and Reconnecting Modes with Phase Velocity in the Ion Diamagnetic Velocity

    NASA Astrophysics Data System (ADS)

    Buratti, P.; Coppi, B.; Basu, B.

    2016-10-01

    The modes that can produce magnetic reconnection in low collisionality regimes and that are driven by the plasma current density gradient are shown to have a characteristic phase velocity in the direction of the ion diamagnetic velocity. Thus the initially formed magnetic islands rotate in the same direction. This result is consistent with the experimental observations of rotating magnetic islands, produced by ``internal modes'' excited in magnetically confined toroidal plasmas, with the caveat that the observed islands have gone through a non-linear evolution that is not covered by the presented theory. In the low collisionality regimes of interest there are to types of singularity to be removed i) that of the perturbed plasma current density removed by a local plasma finite ``inductivity'' ii) that of the perturbed electron temperature (due to a large longitudinal thermal conductivity) removed by a finite transverse electron thermal conductivity. Sponsored by the U.S. D.O.E.

  11. Slip velocity and velocity inversion in a cylindrical Couette flow.

    PubMed

    Kim, Sangrak

    2009-03-01

    Velocity inversion in a nanoscale cylindrical Couette flow is investigated with the Navier-Stokes (NS) equation and molecular-dynamics (MD) simulation. With general slip boundary conditions in the NS equation, the flow can be classified into five distinct profiles. The condition of velocity inversion is explored in the whole space of four dimensionless variables of beta , slip velocity ratio u('), radius ratio a('), and angular velocity ratio omega('). MD computer simulations are performed to estimate the constitutive coefficient of the slip velocities at the walls. The flow is generated by a rotating inner wall and a stationary outer wall in conformity with the theoretical result. By varying an attraction parameter in the Lennard-Jones potential, the slip velocities can be easily controlled. The theoretical predictions are compared with the simulation results. We find that in the intermediate range of the attraction parameter the two results are quite comparable to some extent, but at both extreme values of the attraction parameter, they are quite different.

  12. Horns as particle velocity amplifiers.

    PubMed

    Donskoy, Dimitri M; Cray, Benjamin A

    2011-11-01

    Preliminary measurements and numerical predictions reveal that simple, and relatively small, horns generate remarkable amplification of acoustic particle velocity. For example, below 2 kHz, a 2.5 cm conical horn has a uniform velocity amplification ratio (throat-to-mouth) factor of approximately 3, or, in terms of a decibel level, 9.5 dB. It is shown that the velocity amplification factor depends on the horn's mouth-to-throat ratio as well as, though to a lesser degree, the horn's flare rate. A double horn configuration provides limited additional gain, approximately an increase of up to 25%.

  13. Dendritic Growth Velocities in Microgravity

    NASA Technical Reports Server (NTRS)

    Glicksman, M. E.; Koss, M. B.; Winsa, E. A.

    1994-01-01

    We measured dendritic tip velocities in pure succinonitrile (SCN) in microgravity. using a sequence of telemetered binary images sent to Earth from the Space Shuttle Columbia (STS-62). Growth velocities were measured as a function of the supercooling over the range 0.05-1.5 K. Microgravity observations show that buoyancy-induced convection alters the growth kinetics of SCN dendrites at supercooling as high as 1.3 K. Also, the dendrite velocity data measured under microgravity agree well with the Ivantsov paraboloidal diffusion solution when coupled to a scaling constant of sigma(sup *) = 0.0157.

  14. A HRP study of the relation between cell size and motor unit type in cat ankle extensor motoneurons.

    PubMed

    Burke, R E; Dum, R P; Fleshman, J W; Glenn, L L; Lev-Tov, A; O'Donovan, M J; Pinter, M J

    1982-07-20

    The dimensions of the somata and stem dendrites of 57 alpha- and three gamma-motoneurons, identified as to motor unit type and labeled by intracellular injection of horseradish peroxidase, were measured in the triceps surae and plantaris motor pools. The somata of type S motoneurons tended to be smaller (mean diameter 47.9 micrometers) than those of FF and FR units (52.5 and 53.1 micrometer, respectively) but these mean values were not significantly different and the data distributions showed considerable overlap between the unit types. The mean numbers and diameters of stem dendrites exhibited somewhat larger differences related to motor unit type and some of these were statistically significant. The total membrane area (AN) of each cell was estimated from measurements of the soma and stem dendrites, by using recent data and Ulfhake and Kellerth ('81) to calculate the membrane area of a dendritic tree from stem dendrite diameter. Mean AN varied with motor unit type in the sequence FF greater than FR greater than S (average values: 369 X 100(3) micrometers 2, 323 X 100(3) micrometers 2, and 250 X 100(3) micrometers 2, respectively). There was covariation between AN and the conduction velocity of the motor axon as well as with the force output from the muscle unit. Comparison of AN and motoneuron input resistance (RN) in 19 alpha-motoneurons suggested that the specific resistivity of the cell membrane in type S motoneurons was systematically higher than that characteristic of type FF or FR motoneurons.

  15. Induced velocity field of a jet in a crossflow

    NASA Technical Reports Server (NTRS)

    Fearn, R. L.; Weston, R. P.

    1978-01-01

    An experimental investigation of a subsonic round jet exhausting perpendicularly from a flat plate into a subsonic crosswind of the same temperature was conducted. Velocity and pressure measurements were made in planes perpendicular to the path of the jet for ratios of jet velocity to crossflow velocity ranging from 3 to 10. The results of these measurements are presented in tabular and graphical forms. A pair of diffuse contrarotating vortices is identified as a significant feature of the flow, and the characteristics of the vortices are discussed.

  16. Effect of passive whole body heating on central conduction and cortical excitability in multiple sclerosis patients and healthy controls.

    PubMed

    White, Andrea T; Vanhaitsma, Timothy A; Vener, Jamie; Davis, Scott L

    2013-06-15

    Heat stress is associated with increased fatigue perception and decrements in function for individuals with multiple sclerosis (MS). Similarly, healthy individuals experience decrements in exercise performance during hyperthermia. Alterations in central nervous system (CNS) function during hyperthermia include reduced voluntary activation of muscle and increased effort perception. The purpose of this investigation was to test the hypothesis that passive heat exposure in MS patients will produce increased subjective fatigue and impairments in physiological measures of central conduction and cortical excitability compared with healthy individuals. Eleven healthy individuals and 11 MS patients completed a series of transcranial magnetic stimulation studies to examine central conduction and cortical excitability under thermoneutral and heat-stressed (HS) conditions at rest and after a fatiguing thumb abduction task. Passive heat stress resulted in significantly greater fatigue perception and impairments in force production in MS patients. Central motor conduction time was significantly shorter during HS in controls; however, in MS patients normal increases in conduction velocity with increased temperature were not observed centrally. MS patients also exhibited decreased cortical excitability during HS, evidenced by significant increases in resting motor threshold, decreased MEP amplitude, and decreased recruitment curve slope. Both groups exhibited postexercise depression of MEP amplitude, but the magnitude of these decrements was amplified in MS patients during HS. Taken together, these results suggest that CNS pathology in MS patients played a substantial role in reducing cortical excitability during HS.

  17. Nanoconfined catalytic Ångström-size motors.

    PubMed

    Colberg, Peter H; Kapral, Raymond

    2015-11-14

    Self-propelled chemically powered synthetic micron and nano-scale motors are being intensively studied because of the wide range of potential applications that exploit their directed motion. This paper considers even smaller Ångström-size synthetic motors. Such very small motors in bulk solution display effects arising from their self-propulsion. Recent experiments have shown that small-molecule catalysts and single enzyme molecules exhibit properties that have been attributed to their chemical activity. Molecular dynamics is used to investigate the properties of very small Ångström-size synthetic chemically powered sphere-dimer motors in a simple atomic-like solvent confined between walls separated by distances of tens of nanometers. Evidence for strong structural ordering of the motors between the walls, which reflects the finite size of solvent molecules and depends on solvent depletion forces, is provided. Dynamical properties, such as average motor velocity, orientational relaxation, and mean square displacement, are anisotropic and depend on the distance from the walls. This research provides information needed for potential applications that use molecular-scale motors in the complex confined geometries encountered in biology and the laboratory.

  18. Simulation of surface acoustic wave motor with spherical slider.

    PubMed

    Morita, T; Kurosawa, M K; Higuchi, T

    1999-01-01

    The operation of a surface acoustic wave (SAW) motor using spherical-shaped sliders was demonstrated by Kurosawa et al. (1994). It was necessary to modify the previous simulation models for usual ultrasonic motors because of this slider shape and the high frequency vibration. A conventional ultrasonic motor has a flat contact surface slider and a hundredth driving frequency; so, the tangential motion caused by the elasticity of the slider and stator with regard to the spherical slider of the SAW motor requires further investigation. In this paper, a dynamic simulation model for the SAW motor is proposed. From the simulation result, the mechanism of the SAW motor was clarified (i.e., levitation and contact conditions were repeated during the operation). The transient response of the motor speed was simulated. The relationships between frictional factor and time constant and vibration velocity of the stator and the slider speed were understood. The detailed research regarding the elastic deformation caused by preload would be helpful to construct an exact simulation model for the next work.

  19. A synthetic DNA motor that transports nanoparticles along carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cha, Tae-Gon; Pan, Jing; Chen, Haorong; Salgado, Janette; Li, Xiang; Mao, Chengde; Choi, Jong Hyun

    2014-01-01

    Intracellular protein motors have evolved to perform specific tasks critical to the function of cells such as intracellular trafficking and cell division. Kinesin and dynein motors, for example, transport cargoes in living cells by walking along microtubules powered by adenosine triphosphate hydrolysis. These motors can make discrete 8 nm centre-of-mass steps and can travel over 1 µm by changing their conformations during the course of adenosine triphosphate binding, hydrolysis and product release. Inspired by such biological machines, synthetic analogues have been developed including self-assembled DNA walkers that can make stepwise movements on RNA/DNA substrates or can function as programmable assembly lines. Here, we show that motors based on RNA-cleaving DNA enzymes can transport nanoparticle cargoes--CdS nanocrystals in this case--along single-walled carbon nanotubes. Our motors extract chemical energy from RNA molecules decorated on the nanotubes and use that energy to fuel autonomous, processive walking through a series of conformational changes along the one-dimensional track. The walking is controllable and adapts to changes in the local environment, which allows us to remotely direct `go' and `stop' actions. The translocation of individual motors can be visualized in real time using the visible fluorescence of the cargo nanoparticle and the near-infared emission of the carbon-nanotube track. We observed unidirectional movements of the molecular motors over 3 µm with a translocation velocity on the order of 1 nm min-1 under our experimental conditions.

  20. Nanoconfined catalytic Ångström-size motors

    SciTech Connect

    Colberg, Peter H. Kapral, Raymond

    2015-11-14

    Self-propelled chemically powered synthetic micron and nano-scale motors are being intensively studied because of the wide range of potential applications that exploit their directed motion. This paper considers even smaller Ångström-size synthetic motors. Such very small motors in bulk solution display effects arising from their self-propulsion. Recent experiments have shown that small-molecule catalysts and single enzyme molecules exhibit properties that have been attributed to their chemical activity. Molecular dynamics is used to investigate the properties of very small Ångström-size synthetic chemically powered sphere-dimer motors in a simple atomic-like solvent confined between walls separated by distances of tens of nanometers. Evidence for strong structural ordering of the motors between the walls, which reflects the finite size of solvent molecules and depends on solvent depletion forces, is provided. Dynamical properties, such as average motor velocity, orientational relaxation, and mean square displacement, are anisotropic and depend on the distance from the walls. This research provides information needed for potential applications that use molecular-scale motors in the complex confined geometries encountered in biology and the laboratory.

  1. Nanoconfined catalytic Ångström-size motors

    NASA Astrophysics Data System (ADS)

    Colberg, Peter H.; Kapral, Raymond

    2015-11-01

    Self-propelled chemically powered synthetic micron and nano-scale motors are being intensively studied because of the wide range of potential applications that exploit their directed motion. This paper considers even smaller Ångström-size synthetic motors. Such very small motors in bulk solution display effects arising from their self-propulsion. Recent experiments have shown that small-molecule catalysts and single enzyme molecules exhibit properties that have been attributed to their chemical activity. Molecular dynamics is used to investigate the properties of very small Ångström-size synthetic chemically powered sphere-dimer motors in a simple atomic-like solvent confined between walls separated by distances of tens of nanometers. Evidence for strong structural ordering of the motors between the walls, which reflects the finite size of solvent molecules and depends on solvent depletion forces, is provided. Dynamical properties, such as average motor velocity, orientational relaxation, and mean square displacement, are anisotropic and depend on the distance from the walls. This research provides information needed for potential applications that use molecular-scale motors in the complex confined geometries encountered in biology and the laboratory.

  2. Robust, automatic GPS station velocities and velocity time series

    NASA Astrophysics Data System (ADS)

    Blewitt, G.; Kreemer, C.; Hammond, W. C.

    2014-12-01

    Automation in GPS coordinate time series analysis makes results more objective and reproducible, but not necessarily as robust as the human eye to detect problems. Moreover, it is not a realistic option to manually scan our current load of >20,000 time series per day. This motivates us to find an automatic way to estimate station velocities that is robust to outliers, discontinuities, seasonality, and noise characteristics (e.g., heteroscedasticity). Here we present a non-parametric method based on the Theil-Sen estimator, defined as the median of velocities vij=(xj-xi)/(tj-ti) computed between all pairs (i, j). Theil-Sen estimators produce statistically identical solutions to ordinary least squares for normally distributed data, but they can tolerate up to 29% of data being problematic. To mitigate seasonality, our proposed estimator only uses pairs approximately separated by an integer number of years (N-δt)<(tj-ti )<(N+δt), where δt is chosen to be small enough to capture seasonality, yet large enough to reduce random error. We fix N=1 to maximally protect against discontinuities. In addition to estimating an overall velocity, we also use these pairs to estimate velocity time series. To test our methods, we process real data sets that have already been used with velocities published in the NA12 reference frame. Accuracy can be tested by the scatter of horizontal velocities in the North American plate interior, which is known to be stable to ~0.3 mm/yr. This presents new opportunities for time series interpretation. For example, the pattern of velocity variations at the interannual scale can help separate tectonic from hydrological processes. Without any step detection, velocity estimates prove to be robust for stations affected by the Mw7.2 2010 El Mayor-Cucapah earthquake, and velocity time series show a clear change after the earthquake, without any of the usual parametric constraints, such as relaxation of postseismic velocities to their preseismic values.

  3. How molecular motors are arranged on a cargo is important for vesicular transport.

    PubMed

    Erickson, Robert P; Jia, Zhiyuan; Gross, Steven P; Yu, Clare C

    2011-05-01

    The spatial organization of the cell depends upon intracellular trafficking of cargos hauled along microtubules and actin filaments by the molecular motor proteins kinesin, dynein, and myosin. Although much is known about how single motors function, there is significant evidence that cargos in vivo are carried by multiple motors. While some aspects of multiple motor function have received attention, how the cargo itself--and motor organization on the cargo--affects transport has not been considered. To address this, we have developed a three-dimensional Monte Carlo simulation of motors transporting a spherical cargo, subject to thermal fluctuations that produce both rotational and translational diffusion. We found that these fluctuations could exert a load on the motor(s), significantly decreasing the mean travel distance and velocity of large cargos, especially at large viscosities. In addition, the presence of the cargo could dramatically help the motor to bind productively to the microtubule: the relatively slow translational and rotational diffusion of moderately sized cargos gave the motors ample opportunity to bind to a microtubule before the motor/cargo ensemble diffuses out of range of that microtubule. For rapidly diffusing cargos, the probability of their binding to a microtubule was high if there were nearby microtubules that they could easily reach by translational diffusion. Our simulations found that one reason why motors may be approximately 100 nm long is to improve their 'on' rates when attached to comparably sized cargos. Finally, our results suggested that to efficiently regulate the number of active motors, motors should be clustered together rather than spread randomly over the surface of the cargo. While our simulation uses the specific parameters for kinesin, these effects result from generic properties of the motors, cargos, and filaments, so they should apply to other motors as well.

  4. Electric Motor Thermal Management R&D. Annual Report

    SciTech Connect

    Bennion, Kevin

    2016-04-01

    With the push to reduce component volumes, lower costs, and reduce weight without sacrificing performance or reliability, the challenges associated with thermal management increase for power electronics and electric motors. Thermal management for electric motors will become more important as the automotive industry continues the transition to more electrically dominant vehicle propulsion systems. The transition to more electrically dominant propulsion systems leads to higher-power duty cycles for electric drive systems. Thermal constraints place significant limitations on how electric motors ultimately perform, and as thermal management improves, there will be a direct trade-off between motor performance, efficiency, cost, and the sizing of electric motors to operate within the thermal constraints. The goal of this research project is to support broad industry demand for data, analysis methods, and experimental techniques to improve and better understand motor thermal management. Work in FY15 focused on two areas related to motor thermal management: passive thermal performance and active convective cooling. Passive thermal performance emphasized the thermal impact of materials and thermal interfaces among materials within an assembled motor. The research tasks supported the publication of test methods and data for thermal contact resistances and direction-dependent thermal conductivity within an electric motor. Active convective cooling focused on measuring convective heat-transfer coefficients using automatic transmission fluid (ATF). Data for average convective heat transfer coefficients for direct impingement of ATF jets was published. Also, experimental hardware for mapping local-scale and stator-scale convective heat transfer coefficients for ATF jet impingement were developed.

  5. Flexidrive: a soft artificial muscle motor

    NASA Astrophysics Data System (ADS)

    Anderson, Iain A.; Tse, Tony C. H.; Inamura, Tokushu; O'Brien, Benjamin; McKay, Thomas; Gisby, Todd

    2011-04-01

    We use our thumbs and forefingers to rotate an object such as a control knob on a stereo system by moving our finger relative to our thumb. Motion is imparted without sliding and in a precise manner. In this paper we demonstrate how an artificial muscle membrane can be used to mimic this action. This is achieved by embedding a soft gear within the membrane. Deformation of the membrane results in deformation of the polymer gear and this can be used for motor actuation by rotating the shaft. The soft motors were fabricated from 3M VHB4905 membranes 0.5mm thick that were pre-stretched equibiaxially to a final thickness of 31 μm. Each membrane had polymer acrylic soft gears inserted at the center. Sectors of each membrane (60° sector) were painted on both sides with conducting carbon grease leaving gaps between adjoining sectors to avoid arcing between them. Each sector was electrically connected to a power supply electrode on the rigid acrylic frame via narrow avenues of carbon-grease. The motors were supported in rigid acrylic frames aligned concentrically. A flexible shaft was inserted through both gears. Membranes were charged using a step wave PWM voltage signal delivered using a Biomimetics Lab EAP Control unit. Both membrane viscoelasticity and the resisting torque on the shaft influence motor speed by changing the effective circumference of the flexible gear. This new soft motor opens the door to artificial muscle machines molded as a single part.

  6. Trends in motor gasolines: 1942-1981

    SciTech Connect

    Shelton, E M; Whisman, M L; Woodward, P W

    1982-06-01

    Trends in motor gasolines for the years of 1942 through 1981 have been evaluated based upon data contained in surveys that have been prepared and published by the Bartlesville Energy Technology Center (BETC). These surveys have been published twice annually since 1935 describing the properties of motor gasolines from throughout the country. The surveys have been conducted in cooperation with the American Petroleum Institute (API) since 1948. Various companies from throughout the country obtain samples from retail outlets, analyze the samples by the American Society for Testing and Materials (ASTM) procedures, and report data to the Bartlesville center for compilation, tabulation, calculation, analysis and publication. A typical motor gasoline report covers 2400 samples from service stations throughout the country representing some 48 companies that manufacture and supply gasoline. The reports include trend charts, octane plots, and tables of test results from about a dozen different tests. From these data in 77 semiannual surveys, a summary report has thus been assembled that shows trends in motor gasolines throughout the entire era of winter 1942 to 1943 to the present. Trends of physical properties including octane numbers, antiknock ratings, distillation temperatures, Reid vapor pressure, sulfur and lead content are tabulated, plotted and discussed in the current report. Also included are trend effects of technological advances and the interactions of engine design, societal and political events and prices upon motor gasoline evolution during the 40 year period.

  7. A New Type of Motor: Pneumatic Step Motor

    PubMed Central

    Stoianovici, Dan; Patriciu, Alexandru; Petrisor, Doru; Mazilu, Dumitru; Kavoussi, Louis

    2011-01-01

    This paper presents a new type of pneumatic motor, a pneumatic step motor (PneuStep). Directional rotary motion of discrete displacement is achieved by sequentially pressurizing the three ports of the motor. Pulsed pressure waves are generated by a remote pneumatic distributor. The motor assembly includes a motor, gearhead, and incremental position encoder in a compact, central bore construction. A special electronic driver is used to control the new motor with electric stepper indexers and standard motion control cards. The motor accepts open-loop step operation as well as closed-loop control with position feedback from the enclosed sensor. A special control feature is implemented to adapt classic control algorithms to the new motor, and is experimentally validated. The speed performance of the motor degrades with the length of the pneumatic hoses between the distributor and motor. Experimental results are presented to reveal this behavior and set the expectation level. Nevertheless, the stepper achieves easily controllable precise motion unlike other pneumatic motors. The motor was designed to be compatible with magnetic resonance medical imaging equipment, for actuating an image-guided intervention robot, for medical applications. For this reason, the motors were entirely made of nonmagnetic and dielectric materials such as plastics, ceramics, and rubbers. Encoding was performed with fiber optics, so that the motors are electricity free, exclusively using pressure and light. PneuStep is readily applicable to other pneumatic or hydraulic precision-motion applications. PMID:21528106

  8. Kriging interpolating cosmic velocity field

    NASA Astrophysics Data System (ADS)

    Yu, Yu; Zhang, Jun; Jing, Yipeng; Zhang, Pengjie

    2015-10-01

    Volume-weighted statistics of large-scale peculiar velocity is preferred by peculiar velocity cosmology, since it is free of the uncertainties of galaxy density bias entangled in observed number density-weighted statistics. However, measuring the volume-weighted velocity statistics from galaxy (halo/simulation particle) velocity data is challenging. Therefore, the exploration of velocity assignment methods with well-controlled sampling artifacts is of great importance. For the first time, we apply the Kriging interpolation to obtain the volume-weighted velocity field. Kriging is a minimum variance estimator. It predicts the most likely velocity for each place based on the velocity at other places. We test the performance of Kriging quantified by the E-mode velocity power spectrum from simulations. Dependences on the variogram prior used in Kriging, the number nk of the nearby particles to interpolate, and the density nP of the observed sample are investigated. First, we find that Kriging induces 1% and 3% systematics at k ˜0.1 h Mpc-1 when nP˜6 ×1 0-2(h-1 Mpc )-3 and nP˜6 ×1 0-3(h-1 Mpc )-3 , respectively. The deviation increases for decreasing nP and increasing k . When nP≲6 ×1 0-4(h-1 Mpc )-3 , a smoothing effect dominates small scales, causing significant underestimation of the velocity power spectrum. Second, increasing nk helps to recover small-scale power. However, for nP≲6 ×1 0-4(h-1 Mpc )-3 cases, the recovery is limited. Finally, Kriging is more sensitive to the variogram prior for a lower sample density. The most straightforward application of Kriging on the cosmic velocity field does not show obvious advantages over the nearest-particle method [Y. Zheng, P. Zhang, Y. Jing, W. Lin, and J. Pan, Phys. Rev. D 88, 103510 (2013)] and could not be directly applied to cosmology so far. However, whether potential improvements may be achieved by more delicate versions of Kriging is worth further investigation.

  9. Reconstruction of velocity fields in electromagnetic flow tomography.

    PubMed

    Lehtikangas, Ossi; Karhunen, Kimmo; Vauhkonen, Marko

    2016-06-28

    Electromagnetic flow meters (EMFMs) are the gold standard in measuring flow velocity in process industry. The flow meters can measure the mean flow velocity of conductive liquids and slurries. A drawback of this approach is that the velocity field cannot be determined. Asymmetric axial flows, often encountered in multiphase flows, pipe elbows and T-junctions, are problematic and can lead to serious systematic errors. Recently, electromagnetic flow tomography (EMFT) has been proposed for measuring velocity fields using several coils and a set of electrodes attached to the surface of the pipe. In this work, a velocity field reconstruction method for EMFT is proposed. The method uses a previously developed finite-element-based computational forward model for computing boundary voltages and a Bayesian framework for inverse problems. In the approach, the vz-component of the velocity field along the longitudinal axis of the pipe is estimated on the pipe cross section. Different asymmetric velocity fields encountered near pipe elbows, solids-in-water flows in inclined pipes and in stratified or multiphase flows are tested. The results suggest that the proposed reconstruction method could be used to estimate velocity fields in complicated pipe flows in which the conventional EMFMs have limited accuracy. This article is part of the themed issue 'Supersensing through industrial process tomography'.

  10. Post-impact behavior of composite solid rocket motor cases

    NASA Technical Reports Server (NTRS)

    Highsmith, Alton L.

    1992-01-01

    In recent years, composite materials have seen increasing use in advanced structural applications because of the significant weight savings they offer when compared to more traditional engineering materials. The higher cost of composites must be offset by the increased performance that results from reduced structural weight if these new materials are to be used effectively. At present, there is considerable interest in fabricating solid rocket motor cases out of composite materials, and capitalizing on the reduced structural weight to increase rocket performance. However, one of the difficulties that arises when composite materials are used is that composites can develop significant amounts of internal damage during low velocity impacts. Such low velocity impacts may be encountered in routine handling of a structural component like a rocket motor case. The ability to assess the reduction in structural integrity of composite motor cases that experience accidental impacts is essential if composite rocket motor cases are to be certified for manned flight. The study described herein was an initial investigation of damage development and reduction of tensile strength in an idealized composite subjected to low velocity impacts.

  11. On optimal velocity during cycling.

    PubMed

    Maroński, R

    1994-02-01

    This paper focuses on the solution of two problems related to cycling. One is to determine the velocity as a function of distance which minimizes the cyclist's energy expenditure in covering a given distance in a set time. The other is to determine the velocity as a function of the distance which minimizes time for fixed energy expenditure. To solve these problems, an equation of motion for the cyclist riding over arbitrary terrain is written using Newton's second law. This equation is used to evaluate either energy expenditure or time, and the minimization problems are solved using an optimal control formulation in conjunction with the method of Miele [Optimization Techniques with Applications to Aerospace Systems, pp. 69-98 (1962) Academic Press, New York]. Solutions to both optimal control problems are the same. The solutions are illustrated through two examples. In one example where the relative wind velocity is zero, the optimal cruising velocity is constant regardless of terrain. In the second, where the relative wind velocity fluctuates, the optimal cruising velocity varies.

  12. Sensory-motor transformations for speech occur bilaterally.

    PubMed

    Cogan, Gregory B; Thesen, Thomas; Carlson, Chad; Doyle, Werner; Devinsky, Orrin; Pesaran, Bijan

    2014-03-06

    Historically, the study of speech processing has emphasized a strong link between auditory perceptual input and motor production output. A kind of 'parity' is essential, as both perception- and production-based representations must form a unified interface to facilitate access to higher-order language processes such as syntax and semantics, believed to be computed in the dominant, typically left hemisphere. Although various theories have been proposed to unite perception and production, the underlying neural mechanisms are unclear. Early models of speech and language processing proposed that perceptual processing occurred in the left posterior superior temporal gyrus (Wernicke's area) and motor production processes occurred in the left inferior frontal gyrus (Broca's area). Sensory activity was proposed to link to production activity through connecting fibre tracts, forming the left lateralized speech sensory-motor system. Although recent evidence indicates that speech perception occurs bilaterally, prevailing models maintain that the speech sensory-motor system is left lateralized and facilitates the transformation from sensory-based auditory representations to motor-based production representations. However, evidence for the lateralized computation of sensory-motor speech transformations is indirect and primarily comes from stroke patients that have speech repetition deficits (conduction aphasia) and studies using covert speech and haemodynamic functional imaging. Whether the speech sensory-motor system is lateralized, like higher-order language processes, or bilateral, like speech perception, is controversial. Here we use direct neural recordings in subjects performing sensory-motor tasks involving overt speech production to show that sensory-motor transformations occur bilaterally. We demonstrate that electrodes over bilateral inferior frontal, inferior parietal, superior temporal, premotor and somatosensory cortices exhibit robust sensory-motor neural

  13. Influence of mental practice and movement observation on motor memory, cognitive function and motor performance in the elderly

    PubMed Central

    Altermann, Caroline D. C.; Martins, Alexandre S.; Carpes, Felipe P.; Mello-Carpes, Pâmela B.

    2014-01-01

    Background With aging, it is important to maintain cognitive and motor functions to ensure autonomy and quality of life. During the acquisition of motor skills, it is necessary for the elderly to understand the purpose of the proposed activities. Physical and mental practice, as well as demonstrations, are strategies used to learn movements. Objectives To investigate the influence of mental practice and the observation of movement on motor memory and to understand the relationship between cognitive function and motor performance in the execution of a sequence of digital movements in the elderly. Method This was a cross-sectional study conducted with 45 young and 45 aged subjects. The instruments used were Mini-Mental State Examination (MMSE), Manual Preference Inventory and a Digital Motor Task (composed of a training of a sequence of movements, an interval and a test phase). The subjects were divided into three subgroups: control, mental practice and observation of movement. Results The elderly depend more strongly on mental practice for the acquisition of a motor memory. In comparing the performances of people in different age groups, we found that in the elderly, there was a negative correlation between the MMSE score and the execution time as well as the number of errors in the motor task. Conclusions For the elderly, mental practice can advantage motor performance. Also, there is a significant relationship between cognitive function, learning and the execution of new motor skills. PMID:24839046

  14. Maxillofacial injuries in moose-motor vehicle collisions versus other high-speed motor vehicle collisions

    PubMed Central

    Kim, Sharon; Harrop, A Robertson

    2005-01-01

    BACKGROUND: Anecdotal experience has suggested that there is a higher frequency of maxillofacial injuries among motor vehicle collisions involving moose. OBJECTIVES: A retrospective cohort study design was used to investigate the incidence of various injuries resulting from moose-motor vehicle collisions versus other high-speed motor vehicle collisions. METHODS: A chart review was conducted among patients presenting to a Canadian regional trauma centre during the five-year period from 1996 to 2000. RESULTS: Fifty-seven moose-motor vehicle collisions were identified; 121 high-speed collisions were randomly selected as a control group. Demographic, collision and injury data were collected from these charts and statistically analyzed. The general demographic features of the two groups were similar. Moose collisions were typically frontal impact resulting in windshield damage. The overall injury severity was similar in both groups. Likewise, the frequency of intracranial, spinal, thoracic and extremity injuries was similar for both groups. The group involved in collisions with moose, however, was 1.8 times more likely then controls to sustain a maxillofacial injury (P=0.004) and four times more likely to sustain a maxillofacial fracture (P=0.006). CONCLUSIONS: Occupants of motor vehicles colliding with moose are more likely to sustain maxillofacial injuries than those involved in other types of motor vehicle collisions. It is speculated that this distribution of injuries relates to the mechanism of collision with these large mammals with a high centre of gravity. PMID:24227930

  15. High-Speed Thin Ultrasonic Spindle Motor and Its Application

    NASA Astrophysics Data System (ADS)

    Aoyagi, Manabu; Suzuki, Fumihiro; Tomikawa, Yoshiro; Kano, Ichiro

    2004-05-01

    In this paper, we report an ultrasonic motor capable of high-velocity revolution applicable for long continuous high operation as a microfan. This study is a response to the new challenge of developing a new field of applications for an ultrasonic motor. Ultrasonic motors using a longitudinal-flexural coupling-vibration mode of a thin plate with a vibrating piece or step-horn are considered. A stator vibrator consists of a metal plate sandwiched by two thin unipoled piezoelectric ceramic plates, the electrodes of which are not divided, and this ultrasonic motor can be driven by a single ac source. Not only the coupling between a longitudinal vibration and flexural one but also the transformation of a longitudinal vibration velocity by a vibrating piece λ/4 long and step-horn λ/2 long are used. They will be effective at making the rotary speed fast. As a result, an ultrasonic motor 0.55 mm thick rotated a shaft 1.5 mm in diameter over 8,000 rpm under conditions of an applied voltage of 30 Vp-p and an input power of only 0.16 W.

  16. Magnetostrictive direct drive motor

    NASA Technical Reports Server (NTRS)

    Naik, Dipak; Dehoff, P. H.

    1991-01-01

    Highly magnetostrictive materials such as Tb.3Dy.7Fe2, commercially known as TERFENOL-D, have been used to date in a variety of devices such as high power actuators and linear motors. The larger magnetostriction available in twinned single crystal TERFENOL-D, approx. 2000 ppm at moderate magnetic field strengths, makes possible a new generation of magnetomechanical devices. NASA researchers are studying the potential of this material as the basis for a direct microstepping rotary motor with torque densities on the order of industrial hydraulics and five times greater than that of the most efficient, high power electric motors. Such a motor would be a micro-radian stepper, capable of precision movements and self-braking in the power-off state. Innovative mechanical engineering techniques are juxtaposed on proper magnetic circuit design to reduce losses in structural flexures, inertias, thermal expansions, eddy currents, and magneto-mechanical coupling, thus optimizing motor performance and efficiency. Mathematical models are presented, including magnetic, structural, and both linear and nonlinear dynamic calculations and simulations. In addition, test results on prototypes are presented.

  17. Motor and sensory neuropathy due to myelin infolding and paranodal damage in a transgenic mouse model of Charcot–Marie–Tooth disease type 1C

    PubMed Central

    Lee, Samuel M.; Sha, Di; Mohammed, Anum A.; Asress, Seneshaw; Glass, Jonathan D.; Chin, Lih-Shen; Li, Lian

    2013-01-01

    Charcot–Marie–Tooth disease type 1C (CMT1C) is a dominantly inherited motor and sensory neuropathy. Despite human genetic evidence linking missense mutations in SIMPLE to CMT1C, the in vivo role of CMT1C-linked SIMPLE mutations remains undetermined. To investigate the molecular mechanism underlying CMT1C pathogenesis, we generated transgenic mice expressing either wild-type or CMT1C-linked W116G human SIMPLE. Mice expressing mutant, but not wild type, SIMPLE develop a late-onset motor and sensory neuropathy that recapitulates key clinical features of CMT1C disease. SIMPLE mutant mice exhibit motor and sensory behavioral impairments accompanied by decreased motor and sensory nerve conduction velocity and reduced compound muscle action potential amplitude. This neuropathy phenotype is associated with focally infolded myelin loops that protrude into the axons at paranodal regions and near Schmidt–Lanterman incisures of peripheral nerves. We find that myelin infolding is often linked to constricted axons with signs of impaired axonal transport and to paranodal defects and abnormal organization of the node of Ranvier. Our findings support that SIMPLE mutation disrupts myelin homeostasis and causes peripheral neuropathy via a combination of toxic gain-of-function and dominant-negative mechanisms. The results from this study suggest that myelin infolding and paranodal damage may represent pathogenic precursors preceding demyelination and axonal degeneration in CMT1C patients. PMID:23359569

  18. Repression of inactive motor nerve terminals in partially denervated rat muscle after regeneration of active motor axons.

    PubMed Central

    Ribchester, R R; Taxt, T

    1984-01-01

    The fourth deep lumbrical muscle in the hind foot of adult rats was partially denervated by crushing the sural nerve (s.n.). The denervated muscle fibres became completely reinnervated by sprouts from lateral plantar nerve (l.p.n.) motor axons. By about 20 days after the nerve crush, s.n. motor axons started to reinnervate the muscle. In control muscles, a small proportion of the muscle fibres--about 2.5% of the muscle per motor unit--was reinnervated by s.n. motor axons over the following 20 days. Hence the regenerating terminals were able to re-establish functional synapses, despite the fact that all the muscle fibres were functionally innervated by l.p.n. terminals. When nerve impulse conduction in the l.p.n. was blocked with tetrodotoxin for up to 2 weeks, starting from the time when s.n. axons returned to the muscle, s.n. motor axons retrieved a much larger proportion of the muscle fibres--about 6.5% of the muscle per motor unit. There was a concomitant decrease in the tension produced by the sprouted l.p.n. motor axons. Intracellular recordings showed that many muscle fibres became innervated exclusively by regenerated s.n. motor nerve terminals. Measurements of end-plate potentials suggested that l.p.n. sprouts and the original nerve terminals were eliminated non-selectively. These results suggest that regenerating, active motor nerve terminals have an additional competitive advantage in reinnervating innervated muscles, if the intact terminals are inactive. When the l.p.n. was cut, rather than blocked, extensive reinnervation by the s.n. occurred-about 30% of the muscle per motor unit. This suggests that the absence of an intact nerve terminal in the motor end-plate provides a stronger stimulus than inactivity for synapse formation by regenerating motor axons. PMID:6707966

  19. Relation between cooperative molecular motors and active Brownian particles

    NASA Astrophysics Data System (ADS)

    Touya, Clément; Schwalger, Tilo; Lindner, Benjamin

    2011-05-01

    Active Brownian particles (ABPs), obeying a nonlinear Langevin equation with speed-dependent drift and noise amplitude, are well-known models used to describe self-propelled motion in biology. In this paper we study a model describing the stochastic dynamics of a group of coupled molecular motors (CMMs). Using two independent numerical methods, one based on the stationary velocity distribution of the motors and the other one on the local increments (also known as the Kramers-Moyal coefficients) of the velocity, we establish a connection between the CMM and the ABP models. The parameters extracted for the ABP via the two methods show good agreement for both symmetric and asymmetric cases and are independent of N, the number of motors, provided that N is not too small. This indicates that one can indeed describe the CMM problem with a simpler ABP model. However, the power spectrum of velocity fluctuations in the CMM model reveals a peak at a finite frequency, a peak which is absent in the velocity spectrum of the ABP model. This implies richer dynamic features of the CMM model which cannot be captured by an ABP model.

  20. Lightning location with variable radio wave propagation velocity

    NASA Astrophysics Data System (ADS)

    Liu, Zhongjian; Koh, Kuang Liang; Mezentsev, Andrew; Sugier, Jacqueline; Fullekrug, Martin

    2016-04-01

    Lightning discharges can be located by triangulation of their broadband electromagnetic pulses in long-baseline (~500 km) radio receiver networks. Here we apply the time of arrival difference (TOA) method to electric field recordings with a low frequency radio receiver array consisting of four stations in western Europe. The electromagnetic wave propagation velocity at low radio frequencies is an important input parameter for the TOA calculation and it is normally assumed to be equal to the speed of light. However, the radio wave propagation depends for example on the frequency, ground conductivity and the ionospheric height and small variations can cause location differences from hundreds to thousands of meters, as demonstrated in this study. The radio wave propagation from two VLF transmissions at 20.9 kHz and 23.4 kHz are compared. The results show that the apparent phase velocities are 0.6% slower and 0.5% faster than the speed of light respectively. As a result, a variable velocity is implemented in the TOA method using continuously recorded data on the 8th August 2014, when a mesoscale convective system developed over central France. The lightning locations inferred with a variable wave propagation velocity are more clustered than those using a fixed velocity. The distribution of the lightning velocities in a given geographic area fits a normal distribution that is not centred at the speed of light. As a result, representative velocities can be calculated for smaller regions to generate a velocity map over a larger area of enhanced lightning activity. These results suggest a connection with the ground elevation and/or surface conductivity that might have an impact on the observed wave propagation velocities.

  1. Magnetostrictive direct drive motors

    NASA Technical Reports Server (NTRS)

    Naik, Dipak; Dehoff, P. H.

    1990-01-01

    Developing magnetostrictive direct drive research motors to power robot joints is discussed. These type motors are expected to produce extraordinary torque density, to be able to perform microradian incremental steps and to be self-braking and safe with the power off. Several types of motor designs have been attempted using magnetostrictive materials. One of the candidate approaches (the magnetostrictive roller drive) is described. The method in which the design will function is described as is the reason why this approach is inherently superior to the other approaches. Following this, the design will be modelled and its expected performance predicted. This particular candidate design is currently undergoing detailed engineering with prototype construction and testing scheduled for mid 1991.

  2. Micromachine Wedge Stepping Motor

    SciTech Connect

    Allen, J.J.; Schriner, H.K.

    1998-11-04

    A wedge stepping motor, which will index a mechanism, has been designed and fabricated in the surface rnicromachine SUMMiT process. This device has demonstrated the ability to index one gear tooth at a time with speeds up to 205 teeth/see. The wedge stepper motor has the following features, whi:h will be useful in a number of applications. o The ability to precisely position mechanical components. . Simple pulse signals can be used for operation. o Only 2 drive signals are requixed for operation. o Torque and precision capabilities increase with device size . The device to be indexed is restrained at all times by the wedge shaped tooth that is used for actuation. This paper will discuss the theory of operation and desi=m of the wedge stepping motor. The fabrication and testing of I he device will also be presented.

  3. Bent shaft motor

    DOEpatents

    Benavides, Gilbert L.

    1998-01-01

    A nonelectromagnetic motor comprising a base, a bent shaft which is rotable relative to the base wherein the bent shaft comprises a straight portion aligned with a main axis and an offset portion that is offset with respect to the main axis; and a drive means for driving the offset portion of the bent shaft along a generally circular path in a plane perpendicular to the main axis to rotate the bent shaft. The bent shaft and drive means for driving the bent shaft can be selected from piezoelectric, magnetostrictive, rheological and shape memory alloys. The drive means of the nonelectromagnetic motor can additionally comprise a shell which shell surrounds and houses the bent shaft and precesses or gyrates which in turn causes the bent drive shaft to rotate. The nonelectromagnetic motor does not rely on friction for the application of torque upon a rotor.

  4. Bent shaft motor

    DOEpatents

    Benavides, G.L.

    1998-05-05

    A nonelectromagnetic motor comprising a base, a bent shaft which is rotatable relative to the base wherein the bent shaft comprises a straight portion aligned with a main axis and an offset portion that is offset with respect to the main axis; and a drive means for driving the offset portion of the bent shaft along a generally circular path in a plane perpendicular to the main axis to rotate the bent shaft. The bent shaft and drive means for driving the bent shaft can be selected from piezoelectric, magnetostrictive, rheological and shape memory alloys. The drive means of the nonelectromagnetic motor can additionally comprise a shell which shell surrounds and houses the bent shaft and precesses or gyrates which in turn causes the bent drive shaft to rotate. The nonelectromagnetic motor does not rely on friction for the application of torque upon a rotor. 11 figs.

  5. Correlation of bubble rise velocity and volume

    SciTech Connect

    Burge, C.

    1991-01-01

    This project was conducted at Westinghouse's Savannah River Laboratories (SRL). The goal of SRL is to make certain that the modifications on the reactor are safe for those working at the plant as well as the general public. One of the steps needed to insure safety is the knowledge of the occurrences that result from a plenum pipe breakage. When a plenum pipe breaks, two things occur: air is sucked into the pipe and is trapped in the cooling water; and water used to cool the fuel rods is lost. As a result of these occurrences, the water is slowed down by both the loss in water pressure and the upward force of air bubbles pushing against the downward force of the water. The project required the conducting of tests to find the bubble velocity in an annular ribbed pipe filled with stagnant water. This document discusses the methodology and results of this testing.

  6. Correlation of bubble rise velocity and volume

    SciTech Connect

    Burge, C.

    1991-12-31

    This project was conducted at Westinghouse`s Savannah River Laboratories (SRL). The goal of SRL is to make certain that the modifications on the reactor are safe for those working at the plant as well as the general public. One of the steps needed to insure safety is the knowledge of the occurrences that result from a plenum pipe breakage. When a plenum pipe breaks, two things occur: air is sucked into the pipe and is trapped in the cooling water; and water used to cool the fuel rods is lost. As a result of these occurrences, the water is slowed down by both the loss in water pressure and the upward force of air bubbles pushing against the downward force of the water. The project required the conducting of tests to find the bubble velocity in an annular ribbed pipe filled with stagnant water. This document discusses the methodology and results of this testing.

  7. Determination of failure limits for sterilizable solid rocket motor

    NASA Technical Reports Server (NTRS)

    Lambert, W. L.; Mastrolia, E. J.; Mcconnell, J. D.

    1974-01-01

    A structural evaluation to establish probable failure limits and a series of environmental tests involving temperature cycling, sustained acceleration, and vibration were conducted on an 18-inch diameter solid rocket motor. Despite the fact that thermal, acceleration and vibration loads representing a severe overtest of conventional environmental requirements were imposed on the sterilizable motor, no structural failure of the grain or flexible support system was detected. The following significant conclusions are considered justified. It is concluded that: (1) the flexible grain retention system, which permitted heat sterilization at 275 F on the test motor, can readily be adopted to meet the environmental requirements of an operational motor design, and (2) if further substantiation of structural integrity is desired, the motor used is considered acceptable for static firing.

  8. Shear stress transmission model for the flagellar rotary motor.

    PubMed

    Mitsui, Toshio; Ohshima, Hiroyuki

    2008-09-01

    Most bacteria that swim are propelled by flagellar filaments, which are driven by a rotary motor powered by proton flux. The mechanism of the flagellar motor is discussed by reforming the model proposed by the present authors in 2005. It is shown that the mean strength of Coulomb field produced by a proton passing the channel is very strong in the Mot assembly so that the Mot assembly can be a shear force generator and induce the flagellar rotation. The model gives clear calculation results in agreement with experimental observations, e g., for the characteristic torque-velocity relationship of the flagellar rotation.

  9. The functional alterations associated with motor imagery training: a comparison between motor execution and motor imagery of sequential finger tapping

    NASA Astrophysics Data System (ADS)

    Zhang, Hang; Yao, Li; Long, Zhiying

    2011-03-01

    Motor imagery training, as an effective strategy, has been more and more applied to mental disorders rehabilitation and motor skill learning. Studies on the neural mechanism underlying motor imagery have suggested that such effectiveness may be related to the functional congruence between motor execution and motor imagery. However, as compared to the studies on motor imagery, the studies on motor imagery training are much fewer. The functional alterations associated with motor imagery training and the effectiveness of motor imagery training on motor performance improvement still needs further investigation. Using fMRI, we employed a sequential finger tapping paradigm to explore the functional alterations associated with motor imagery training in both motor execution and motor imagery task. We hypothesized through 14 consecutive days motor imagery training, the motor performance could be improved and the functional congruence between motor execution and motor imagery would be sustained form pre-training phase to post-training phase. Our results confirmed the effectiveness of motor imagery training in improving motor performance and demonstrated in both pre and post-training phases, motor imagery and motor execution consistently sustained the congruence in functional neuroanatomy, including SMA (supplementary motor cortex), PMA (premotor area); M1( primary motor cortex) and cerebellum. Moreover, for both execution and imagery tasks, a similar functional alteration was observed in fusiform through motor imagery training. These findings provided an insight into the effectiveness of motor imagery training and suggested its potential therapeutic value in motor rehabilitation.

  10. Heat conduction in conducting polyaniline nanofibers

    NASA Astrophysics Data System (ADS)

    Nath, Chandrani; Kumar, A.; Syu, K.-Z.; Kuo, Y.-K.

    2013-09-01

    Thermal conductivity and specific heat of conducting polyaniline nanofibers are measured to identify the nature of heat carrying modes combined with their inhomogeneous structure. The low temperature thermal conductivity results reveal crystalline nature while the high temperature data confirm the amorphous nature of the material suggesting heterogeneous model for conducting polyaniline. Extended acoustic phonons dominate the low temperature (<100 K) heat conduction, while localized optical phonons hopping, assisted by the extended acoustic modes, account for the high temperature (>100 K) heat conduction.

  11. ac bidirectional motor controller

    NASA Technical Reports Server (NTRS)

    Schreiner, K.

    1988-01-01

    Test data are presented and the design of a high-efficiency motor/generator controller at NASA-Lewis for use with the Space Station power system testbed is described. The bidirectional motor driver is a 20 kHz to variable frequency three-phase ac converter that operates from the high-frequency ac bus being designed for the Space Station. A zero-voltage-switching pulse-density-modulation technique is used in the converter to shape the low-frequency output waveform.

  12. Motor current signature analysis method for diagnosing motor operated devices

    DOEpatents

    Haynes, Howard D.; Eissenberg, David M.

    1990-01-01

    A motor current noise signature analysis method and apparatus for remotely monitoring the operating characteristics of an electric motor-operated device such as a motor-operated valve. Frequency domain signal analysis techniques are applied to a conditioned motor current signal to distinctly identify various operating parameters of the motor driven device from the motor current signature. The signature may be recorded and compared with subsequent signatures to detect operating abnormalities and degradation of the device. This diagnostic method does not require special equipment to be installed on the motor-operated device, and the current sensing may be performed at remote control locations, e.g., where the motor-operated devices are used in accessible or hostile environments.

  13. Fluoxetine modulates motor performance and cerebral activation of patients recovering from stroke.

    PubMed

    Pariente, J; Loubinoux, I; Carel, C; Albucher, J F; Leger, A; Manelfe, C; Rascol, O; Chollet, F

    2001-12-01

    In order to determine the influence of a single dose of fluoxetine on the cerebral motor activation of lacunar stroke patients in the early phase of recovery, we conducted a prospective, double-blind, crossover, placebo-controlled study on 8 patients with pure motor hemiparesia. Each patient underwent two functional magnetic resonance imaging (fMRI) examinations: one under fluoxetine and one under placebo. The first was performed 2 weeks after stroke onset and the second a week later. During the two fMRI examinations, patients performed an active controlled motor task with the affected hand and a passive one conducted by the examiner with the same hand. Motor performance was evaluated by motor tests under placebo and under fluoxetine immediately before the examinations to investigate the effect of fluoxetine on motor function. Under fluoxetine, during the active motor task, hyperactivation in the ipsilesional primary motor cortex was found. Moreover, fluoxetine significantly improved motor skills of the affected side. We found that a single dose of fluoxetine was enough to modulate cerebral sensory-motor activation in patients. This redistribution of activation toward the motor cortex output activation was associated with an enhancement of motor performance.

  14. Thermal conductivity of sputtered amorphous Ge films

    SciTech Connect

    Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka

    2014-02-15

    We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids.

  15. A Stochastic Model for Microtubule Motors Describes the In Vivo Cytoplasmic Transport of Human Adenovirus

    PubMed Central

    Gazzola, Mattia; Burckhardt, Christoph J.; Bayati, Basil; Engelke, Martin; Greber, Urs F.; Koumoutsakos, Petros

    2009-01-01

    Cytoplasmic transport of organelles, nucleic acids and proteins on microtubules is usually bidirectional with dynein and kinesin motors mediating the delivery of cargoes in the cytoplasm. Here we combine live cell microscopy, single virus tracking and trajectory segmentation to systematically identify the parameters of a stochastic computational model of cargo transport by molecular motors on microtubules. The model parameters are identified using an evolutionary optimization algorithm to minimize the Kullback-Leibler divergence between the in silico and the in vivo run length and velocity distributions of the viruses on microtubules. The present stochastic model suggests that bidirectional transport of human adenoviruses can be explained without explicit motor coordination. The model enables the prediction of the number of motors active on the viral cargo during microtubule-dependent motions as well as the number of motor binding sites, with the protein hexon as the binding site for the motors. PMID:20041204

  16. A stochastic model for microtubule motors describes the in vivo cytoplasmic transport of human adenovirus.

    PubMed

    Gazzola, Mattia; Burckhardt, Christoph J; Bayati, Basil; Engelke, Martin; Greber, Urs F; Koumoutsakos, Petros

    2009-12-01

    Cytoplasmic transport of organelles, nucleic acids and proteins on microtubules is usually bidirectional with dynein and kinesin motors mediating the delivery of cargoes in the cytoplasm. Here we combine live cell microscopy, single virus tracking and trajectory segmentation to systematically identify the parameters of a stochastic computational model of cargo transport by molecular motors on microtubules. The model parameters are identified using an evolutionary optimization algorithm to minimize the Kullback-Leibler divergence between the in silico and the in vivo run length and velocity distributions of the viruses on microtubules. The present stochastic model suggests that bidirectional transport of human adenoviruses can be explained without explicit motor coordination. The model enables the prediction of the number of motors active on the viral cargo during microtubule-dependent motions as well as the number of motor binding sites, with the protein hexon as the binding site for the motors.

  17. The design and experiment of a novel ultrasonic motor based on the combination of bending modes.

    PubMed

    Yan, Jipeng; Liu, Yingxiang; Liu, Junkao; Xu, Dongmei; Chen, Weishan

    2016-09-01

    This paper presents a new-type linear ultrasonic motor which takes advantage of the combination of two orthogonal bending vibration modes. The proposed ultrasonic motor consists of eight pieces of PZT ceramic plates and a metal beam that includes two cone-shaped horns and a cylindrical driving foot. The finite element analyses were finished to verify the working principle of the proposed motor. The mode shapes of the motor were obtained by modal analysis; the elliptical trajectories of nodes on the driving foot were obtained by time-domain analysis. Based on the analyses, a prototype of the proposed motor was fabricated and measured. The mechanical output characteristics were obtained by experiments. The maximal velocity of the proposed motor is 735mm/s and the maximal thrust is 1.1N.

  18. Evidence for an electrostatic mechanism of force generation by the bacteriophage T4 DNA packaging motor

    NASA Astrophysics Data System (ADS)

    Migliori, Amy D.; Keller, Nicholas; Alam, Tanfis I.; Mahalingam, Marthandan; Rao, Venigalla B.; Arya, Gaurav; Smith, Douglas E.

    2014-06-01

    How viral packaging motors generate enormous forces to translocate DNA into viral capsids remains unknown. Recent structural studies of the bacteriophage T4 packaging motor have led to a proposed mechanism wherein the gp17 motor protein translocates DNA by transitioning between extended and compact states, orchestrated by electrostatic interactions between complimentarily charged residues across the interface between the N- and C-terminal subdomains. Here we show that site-directed alterations in these residues cause force dependent impairments of motor function including lower translocation velocity, lower stall force and higher frequency of pauses and slips. We further show that the measured impairments correlate with computed changes in free-energy differences between the two states. These findings support the proposed structural mechanism and further suggest an energy landscape model of motor activity that couples the free-energy profile of motor conformational states with that of the ATP hydrolysis cycle.

  19. Calibration method helps in seismic velocity interpretation

    SciTech Connect

    Guzman, C.E.; Davenport, H.A.; Wilhelm, R.

    1997-11-03

    Acoustic velocities derived from seismic reflection data, when properly calibrated to subsurface measurements, help interpreters make pure velocity predictions. A method of calibrating seismic to measured velocities has improved interpretation of subsurface features in the Gulf of Mexico. In this method, the interpreter in essence creates a kind of gauge. Properly calibrated, the gauge enables the interpreter to match predicted velocities to velocities measured at wells. Slow-velocity zones are of special interest because they sometimes appear near hydrocarbon accumulations. Changes in velocity vary in strength with location; the structural picture is hidden unless the variations are accounted for by mapping in depth instead of time. Preliminary observations suggest that the presence of hydrocarbons alters the lithology in the neighborhood of the trap; this hydrocarbon effect may be reflected in the rock velocity. The effect indicates a direct use of seismic velocity in exploration. This article uses the terms seismic velocity and seismic stacking velocity interchangeably. It uses ground velocity, checkshot average velocity, and well velocity interchangeably. Interval velocities are derived from seismic stacking velocities or well average velocities; they refer to velocities of subsurface intervals or zones. Interval travel time (ITT) is the reciprocal of interval velocity in microseconds per foot.

  20. 46 CFR 169.684 - Overcurrent protection for motors and motor branch circuits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Overcurrent protection for motors and motor branch... motors and motor branch circuits. (a) Except as provided in paragraph (d) of this section, each motor... motor that is responsive to motor current or to both motor current and temperature may be used. (b)...

  1. 46 CFR 169.684 - Overcurrent protection for motors and motor branch circuits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Overcurrent protection for motors and motor branch... motors and motor branch circuits. (a) Except as provided in paragraph (d) of this section, each motor... motor that is responsive to motor current or to both motor current and temperature may be used. (b)...

  2. Tangential Velocity Measurement Using Interferometric MTI Radar

    SciTech Connect

    DOERRY, ARMIN W.; MILESHOSKY, BRIAN P.; BICKEL, DOUGLAS L.

    2002-11-01

    An Interferometric Moving Target Indicator radar can be used to measure the tangential velocity component of a moving target. Multiple baselines, along with the conventional radial velocity measurement, allow estimating the true 3-D velocity vector of a target.

  3. Signal velocity in oscillator arrays

    NASA Astrophysics Data System (ADS)

    Cantos, C. E.; Veerman, J. J. P.; Hammond, D. K.

    2016-09-01

    We investigate a system of coupled oscillators on the circle, which arises from a simple model for behavior of large numbers of autonomous vehicles where the acceleration of each vehicle depends on the relative positions and velocities between itself and a set of local neighbors. After describing necessary and sufficient conditions for asymptotic stability, we derive expressions for the phase velocity of propagation of disturbances in velocity through this system. We show that the high frequencies exhibit damping, which implies existence of well-defined signal velocitiesc+ > 0 and c- < 0 such that low frequency disturbances travel through the flock as f+(x - c+t) in the direction of increasing agent numbers and f-(x - c-t) in the other.

  4. An ironless armature brushless torque motor

    NASA Technical Reports Server (NTRS)

    Studer, P. A.

    1973-01-01

    A high torque motor with improved servo mechanism is reported. Armature windings are cast into an epoxy cylinder and armature conductors are integrally cast with an aluminum mounting ring which provides thermal conductance directly into the structure. This configuration eliminates magnetic hysteresis because there is no relative motion between the rotating magnetic field and any stationary iron. The absence of destabilization forces provides a fast electrical response compared with a typical torquer of conventional construction.

  5. Magnetically Coupled Adjustable Speed Motor Drives - Motor Tip Sheet #13

    SciTech Connect

    2008-07-01

    Alternating current electric motors rotate at a nearly constant speed that is determined by motor design and line frequency. Energy savings of 50% or more may be available when fixed speed systems are modified to allow the motor speed to match variable load requirements of a centrifugal fan or pump.

  6. Method for assessing motor insulation on operating motors

    DOEpatents

    Kueck, J.D.; Otaduy, P.J.

    1997-03-18

    A method for monitoring the condition of electrical-motor-driven devices is disclosed. The method is achieved by monitoring electrical variables associated with the functioning of an operating motor, applying these electrical variables to a three phase equivalent circuit and determining non-symmetrical faults in the operating motor based upon symmetrical components analysis techniques. 15 figs.

  7. Method for assessing motor insulation on operating motors

    DOEpatents

    Kueck, John D.; Otaduy, Pedro J.

    1997-01-01

    A method for monitoring the condition of electrical-motor-driven devices. The method is achieved by monitoring electrical variables associated with the functioning of an operating motor, applying these electrical variables to a three phase equivalent circuit and determining non-symmetrical faults in the operating motor based upon symmetrical components analysis techniques.

  8. Probability detection mechanisms and motor learning.

    PubMed

    Lungu, O V; Wächter, T; Liu, T; Willingham, D T; Ashe, J

    2004-11-01

    The automatic detection of patterns or regularities in the environment is central to certain forms of motor learning, which are largely procedural and implicit. The rules underlying the detection and use of probabilistic information in the perceptual-motor domain are largely unknown. We conducted two experiments involving a motor learning task with direct and crossed mapping of motor responses in which probabilities were present at the stimulus set level, the response set level, and at the level of stimulus-response (S-R) mapping. We manipulated only one level at a time, while controlling for the other two. The results show that probabilities were detected only when present at the S-R mapping and motor levels, but not at the perceptual one (experiment 1), unless the perceptual features have a dimensional overlap with the S-R mapping rule (experiment 2). The effects of probability detection were mostly facilitatory at the S-R mapping, both facilitatory and inhibitory at the perceptual level, and predominantly inhibitory at the response-set level. The facilitatory effects were based on learning the absolute frequencies first and transitional probabilities later (for the S-R mapping rule) or both types of information at the same time (for perceptual level), whereas the inhibitory effects were based on learning first the transitional probabilities. Our data suggest that both absolute frequencies and transitional probabilities are used in motor learning, but in different temporal orders, according to the probabilistic properties of the environment. The results support the idea that separate neural circuits may be involved in detecting absolute frequencies as compared to transitional probabilities.

  9. Hybrid-fuel bacterial flagellar motors in Escherichia coli.

    PubMed

    Sowa, Yoshiyuki; Homma, Michio; Ishijima, Akihiko; Berry, Richard M

    2014-03-04

    The bacterial flagellar motor rotates driven by an electrochemical ion gradient across the cytoplasmic membrane, either H(+) or Na(+) ions. The motor consists of a rotor ∼50 nm in diameter surrounded by multiple torque-generating ion-conducting stator units. Stator units exchange spontaneously between the motor and a pool in the cytoplasmic membrane on a timescale of minutes, and their stability in the motor is dependent upon the ion gradient. We report a genetically engineered hybrid-fuel flagellar motor in Escherichia coli that contains both H(+)- and Na(+)-driven stator components and runs on both types of ion gradient. We controlled the number of each type of stator unit in the motor by protein expression levels and Na(+) concentration ([Na(+)]), using speed changes of single motors driving 1-μm polystyrene beads to determine stator unit numbers. De-energized motors changed from locked to freely rotating on a timescale similar to that of spontaneous stator unit exchange. Hybrid motor speed is simply the sum of speeds attributable to individual stator units of each type. With Na(+) and H(+) stator components expressed at high and medium levels, respectively, Na(+) stator units dominate at high [Na(+)] and are replaced by H(+) units when Na(+) is removed. Thus, competition between stator units for spaces in a motor and sensitivity of each type to its own ion gradient combine to allow hybrid motors to adapt to the prevailing ion gradient. We speculate that a similar process may occur in species that naturally express both H(+) and Na(+) stator components sharing a common rotor.

  10. Motor planning modulates sensory-motor control of collision avoidance behavior in the bullfrog, Rana catesbeiana

    PubMed Central

    Nakagawa, Hideki; Nishida, Yuuya

    2012-01-01

    Summary In this study, we examined the collision avoidance behavior of the frog, Rana catesbeiana to an approaching object in the upper visual field. The angular velocity of the frog's escape turn showed a significant positive correlation with the turn angle (r2 = 0.5741, P<0.05). A similar mechanism of velocity control has been known in head movements of the owl and in human saccades. By analogy, this suggests that the frog planned its escape velocity in advance of executing the turn, to make the duration of the escape behavior relatively constant. For escape turns less than 60°, the positive correlation was very strong (r2 = 0.7097, P<0.05). Thus, the frog controlled the angular velocity of small escape turns very accurately and completed the behavior within a constant time. On the other hand, for escape turns greater than 60°, the same correlation was not significant (r2 = 0.065, P>0.05). Thus, the frog was not able to control the velocity of the large escape turns accurately and did not complete the behavior within a constant time. In the latter case, there was a small but significant positive correlation between the threshold angular size and the angular velocity (r2 = 0.1459, P<0.05). This suggests that the threshold is controlled to compensate for the insufficient escape velocity achieved during large turn angles, and could explain a significant negative correlation between the turn angle and the threshold angular size (r2 = 0.1145, P<0.05). Thus, it is likely that the threshold angular size is also controlled by the turn angle and is modulated by motor planning. PMID:23213389

  11. Motor planning modulates sensory-motor control of collision avoidance behavior in the bullfrog, Rana catesbeiana.

    PubMed

    Nakagawa, Hideki; Nishida, Yuuya

    2012-11-15

    In this study, we examined the collision avoidance behavior of the frog, Rana catesbeiana to an approaching object in the upper visual field. The angular velocity of the frog's escape turn showed a significant positive correlation with the turn angle (r(2) = 0.5741, P<0.05). A similar mechanism of velocity control has been known in head movements of the owl and in human saccades. By analogy, this suggests that the frog planned its escape velocity in advance of executing the turn, to make the duration of the escape behavior relatively constant. For escape turns less than 60°, the positive correlation was very strong (r(2) = 0.7097, P<0.05). Thus, the frog controlled the angular velocity of small escape turns very accurately and completed the behavior within a constant time. On the other hand, for escape turns greater than 60°, the same correlation was not significant (r(2) = 0.065, P>0.05). Thus, the frog was not able to control the velocity of the large escape turns accurately and did not complete the behavior within a constant time. In the latter case, there was a small but significant positive correlation between the threshold angular size and the angular velocity (r(2) = 0.1459, P<0.05). This suggests that the threshold is controlled to compensate for the insufficient escape velocity achieved during large turn angles, and could explain a significant negative correlation between the turn angle and the threshold angular size (r(2) = 0.1145, P<0.05). Thus, it is likely that the threshold angular size is also controlled by the turn angle and is modulated by motor planning.

  12. Electric motor model repair specifications

    SciTech Connect

    1995-08-01

    These model repair specifications list the minimum requirements for repair and overhaul of polyphase AC squireel cage induction motors. All power ranges, voltages, and speeds of squirrel cage motors are covered.

  13. Measurement of turbulent wind velocities using a rotating boom apparatus

    SciTech Connect

    Sandborn, V.A.; Connell, J.R.

    1984-04-01

    The present report covers both the development of a rotating-boom facility and the evaluation of the spectral energy of the turbulence measured relative to the rotating boom. The rotating boom is composed of a helicopter blade driven through a pulley speed reducer by a variable speed motor. The boom is mounted on a semiportable tower that can be raised to provide various ratios of hub height to rotor diameter. The boom can be mounted to rotate in either the vertical or horizontal plane. Probes that measure the three components of turbulence can be mounted at any location along the radius of the boom. Special hot-film sensors measured two components of the turbulence at a point directly in front of the rotating blade. By using the probe rotated 90/sup 0/ about its axis, the third turbulent velocity component was measured. Evaluation of the spectral energy distributions for the three components of velocity indicates a large concentration of energy at the rotational frequency. At frequencies slightly below the rotational frequency, the spectral energy is greatly reduced over that measured for the nonrotating case measurements. Peaks in the energy at frequencies that are multiples of the rotation frequency were also observed. We conclude that the rotating boom apparatus is suitable and ready to be used in experiments for developing and testing sensors for rotational measurement of wind velocity from wind turbine rotors. It also can be used to accurately measure turbulent wind for testing theories of rotationally sampled wind velocity.

  14. Interaction of motor proteins of various types at melanosome redistribution in melanocytes under action of UV radiation

    NASA Astrophysics Data System (ADS)

    Stolnitz, Mikhail M.; Kudryashov, Alexey A.

    2004-05-01

    In the report the mathematical model of melanosome transport along filaments in intact and UV-irradiated melanocytes is submitted. Processes at three levels are considered: dynamics of the single motor, transport of melanosome by ensemble of motors, and melanosomes distribution along microtubules. A single motor is considered as <> modeling of transitions between internal states described by chemical kinetics equations allows to determine "force-velocity" dependence for motor. The ensemble of motors is described by system of equations for average motor velocities, and transported melanosome moves with average velocity, which in turn is determined by sum of force generated by each elastic-coupled motor (self-consistence problem). Distribution of melanosomes along a microtubule is described by system of equations for bidirectional motion of attached melanosome under coordinated action of "plus-end" and "minus-end" motors and free diffusion of unattached melanosomes. Influence of UV-radiation is resulted in change of number of each type motors simultaneously linked to one melanosome. It induces redistribution of melanosomes between centre and periphery of melanocyte.

  15. Reciprocating Linear Electric Motor

    NASA Technical Reports Server (NTRS)

    Goldowsky, M. P.

    1984-01-01

    Features include structural simplicity and good force/displacement characteristics. Reciprocating motor has simple, rugged construction, relatively low reciprocating weight, improved power delivery, and improved force control. Wear reduced by use of magnetic bearings. Intended to provide drivers for long-lived Stirling-cycle cryogenic refrigerators, concept has less exotic applications, such as fuel pumps.

  16. Perceptual-Motor Dysfunction.

    ERIC Educational Resources Information Center

    Pyfer, Jean L.

    Discussed are theoretical and treatment aspects of perceptual motor dysfunction and rehabilitation in 4- to 12-year-old academically failing children involved in a 3-year investigation at the University of Kansas. The program is said to stress increasing the amount of stimulation received by sensory receptors of the vestibular, reflex, and haptic…

  17. Thiokol Solid Rocket Motors

    NASA Technical Reports Server (NTRS)

    Graves, S. R.

    2000-01-01

    This paper presents viewgraphs on thiokol solid rocket motors. The topics include: 1) Communications; 2) Military and government intelligence; 3) Positioning satellites; 4) Remote sensing; 5) Space burial; 6) Science; 7) Space manufacturing; 8) Advertising; 9) Space rescue space debris management; 10) Space tourism; 11) Space settlements; 12) Hazardous waste disposal; 13) Extraterrestrial resources; 14) Fast package delivery; and 15) Space utilities.

  18. The St. Louis Motor

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2011-01-01

    The St. Louis Motor, invented in 1909, is unique among physics apparatus for being named for a geographical place rather than a physicist. The sturdy little device (Fig. 1) has never been out of production. Any older school or physics department that has not done a catastrophic housecleaning in the last 20 years will certainly have a small flock…

  19. Development of a miniature solid propellant rocket motor for use in plume simulation studies

    NASA Technical Reports Server (NTRS)

    Baran, W. J.

    1974-01-01

    A miniature solid propellant rocket motor has been developed to be used in a program to determine those parameters which must be duplicated in a cold gas flow to produce aerodynamic effects on an experimental model similar to those produced by hot, particle-laden exhaust plumes. Phenomena encountered during the testing of the miniature solid propellant motors included erosive propellant burning caused by high flow velocities parallel to the propellant surface, regressive propellant burning as a result of exposed propellant edges, the deposition of aluminum oxide on the nozzle surfaces sufficient to cause aerodynamic nozzle throat geometry changes, and thermal erosion of the nozzle throat at high chamber pressures. A series of tests was conducted to establish the stability of the rocket chamber pressure and the repeatibility of test conditions. Data are presented which define the tests selected to represent the final test matrix. Qualitative observations are also presented concerning the phenomena experienced based on the results of a large number or rocket tests not directly applicable to the final test matrix.

  20. Motor features in posterior cortical atrophy and their imaging correlates☆

    PubMed Central

    Ryan, Natalie S.; Shakespeare, Timothy J.; Lehmann, Manja; Keihaninejad, Shiva; Nicholas, Jennifer M.; Leung, Kelvin K.; Fox, Nick C.; Crutch, Sebastian J.

    2014-01-01

    Posterior cortical atrophy (PCA) is a neurodegenerative syndrome characterized by impaired higher visual processing skills; however, motor features more commonly associated with corticobasal syndrome may also occur. We investigated the frequency and clinical characteristics of motor features in 44 PCA patients and, with 30 controls, conducted voxel-based morphometry, cortical thickness, and subcortical volumetric analyses of their magnetic resonance imaging. Prominent limb rigidity was used to define a PCA-motor subgroup. A total of 30% (13) had PCA-motor; all demonstrating asymmetrical left upper limb rigidity. Limb apraxia was more frequent and asymmetrical in PCA-motor, as was myoclonus. Tremor and alien limb phenomena only occurred in this subgroup. The subgroups did not differ in neuropsychological test performance or apolipoprotein E4 allele frequency. Greater asymmetry of atrophy occurred in PCA-motor, particularly involving right frontoparietal and peri-rolandic cortices, putamen, and thalamus. The 9 patients (including 4 PCA-motor) with pathology or cerebrospinal fluid all showed evidence of Alzheimer's disease. Our data suggest that PCA patients with motor features have greater atrophy of contralateral sensorimotor areas but are still likely to have underlying Alzheimer's disease. PMID:25086839

  1. Optimization of Motor/Gear Drive System for Electric RPV.

    DTIC Science & Technology

    1986-10-01

    dc motor for propulsion in an RPV application. The electric propulsion system would include a brushless dc motor , electronic controller, and gear reducer that is optimally sized for the cruise condition of an RPV. Performance tests were to be conducted to measure developed power, while driving a propeller loaded at the cruise condition, and to test for the adequacy of heat rejection from the motor in the RPV configuration. The system was to be packaged for minimum size and weight. A complete electric propulsion system consisting of a brushless dc

  2. Velocity modulation of electron transport through a ferromagnetic silicene junction

    NASA Astrophysics Data System (ADS)

    Huai-Hua, Shao; Dan, Guo; Ben-Liang, Zhou; Guang-Hui, Zhou

    2016-03-01

    We address velocity-modulation control of electron wave propagation in a normal/ferromagnetic/normal silicene junction with local variation of Fermi velocity, where the properties of charge, valley, and spin transport through the junction are investigated. By matching the wavefunctions at the normal-ferromagnetic interfaces, it is demonstrated that the variation of Fermi velocity in a small range can largely enhance the total conductance while keeping the current nearly fully valley- and spin-polarized. Further, the variation of Fermi velocity in ferromagnetic silicene has significant influence on the valley and spin polarization, especially in the low-energy regime. It may drastically reduce the high polarizations, which can be realized by adjusting the local application of a gate voltage and exchange field on the junction. Project supported by the National Natural Science Foundation of China (Grant No. 11274108).

  3. Temperature and velocity profiles in sooting free boundary layer flames

    NASA Technical Reports Server (NTRS)

    Ang, J. A.; Pagni, P. J.; Mataga, T. G.; Margle, J. M.; Lyons, V. J.

    1986-01-01

    Temperature and velocity profiles are presented for cyclohexane, n-heptane, and iso-octane free, laminar, boundary layer, sooting, diffusion flames. Temperatures are measured with 3 mil Pt/Pt-13 percent Rh thermocouples. Corrected gas temperatures are derived by performing an energy balance of convection to and radiation from the thermocouple bead incorporating the variation of air conductivity and platinum emissivity with temperature. Velocities are measured using laser doppler velocimetry techniques. Profiles are compared with previously reported analytic temperature and velocity fields. Comparison of theoretical and experimental temperature profiles suggests improvement in the analytical treatment is needed, which accounts more accurately for the local soot radiation. The velocity profiles are in good agreement, with the departure of the theory from observation partially due to the small fluctuations inherent in these free flows.

  4. Memory processes and motor control in extreme environments.

    PubMed

    Newman, D J; Lathan, C E

    1999-08-01

    Cognitive-performance and motor-performance activities in multi-task, high-workload environments were assessed during astronaut performance in space flight and in isolation. Data was collected in microgravity on the International Micro-gravity Laboratory (IML) space shuttle mission (STS-42), and the Canadian Astronaut Program Space Unit Life Simulation (CAPSULS) mission offered an ideal opportunity to collect data for individuals in extreme isolation to complement the space flight data using similar hardware, software, and experimental protocols. The mental workload and performance experiment (MWPE) was performed during the IML-1 space flight mission, and the memory processes and motor control (MEMO) experiment was performed during the CAPSULS isolation mission. In both experiments, short-term exhaustive memory and fine motor control associated with human-computer interaction was studied. Memory processes were assessed using a Sternberg-like exhaustive memory search containing 1, 2, 4, or 7 letters. Fine motor control was assessed using velocity-controlled (joystick) and position-controlled (trackball) computer input devices to acquire targets as displayed on a computer screen. Subjects repeated the tasks under two conditions that tested perceptual motor adaptation strategies: 1) During adaptation to the microgravity environment; and 2) While wearing left-right reversing prism goggles during the CAPSULS mission. Both conditions significantly degraded motor performance but not cognitive performance. The data collected during both the MEMO experiment and the MWPE experiments enhance the knowledge base of human interface technology for human performance in extreme environments.

  5. Omnidirectional Sensory and Motor Volumes in Electric Fish

    PubMed Central

    Snyder, James B; Nelson, Mark E; Burdick, Joel W; MacIver, Malcolm A

    2007-01-01

    Active sensing organisms, such as bats, dolphins, and weakly electric fish, generate a 3-D space for active sensation by emitting self-generated energy into the environment. For a weakly electric fish, we demonstrate that the electrosensory space for prey detection has an unusual, omnidirectional shape. We compare this sensory volume with the animal's motor volume—the volume swept out by the body over selected time intervals and over the time it takes to come to a stop from typical hunting velocities. We find that the motor volume has a similar omnidirectional shape, which can be attributed to the fish's backward-swimming capabilities and body dynamics. We assessed the electrosensory space for prey detection by analyzing simulated changes in spiking activity of primary electrosensory afferents during empirically measured and synthetic prey capture trials. The animal's motor volume was reconstructed from video recordings of body motion during prey capture behavior. Our results suggest that in weakly electric fish, there is a close connection between the shape of the sensory and motor volumes. We consider three general spatial relationships between 3-D sensory and motor volumes in active and passive-sensing animals, and we examine hypotheses about these relationships in the context of the volumes we quantify for weakly electric fish. We propose that the ratio of the sensory volume to the motor volume provides insight into behavioral control strategies across all animals. PMID:18001151

  6. Omnidirectional sensory and motor volumes in electric fish.

    PubMed

    Snyder, James B; Nelson, Mark E; Burdick, Joel W; Maciver, Malcolm A

    2007-11-01

    Active sensing organisms, such as bats, dolphins, and weakly electric fish, generate a 3-D space for active sensation by emitting self-generated energy into the environment. For a weakly electric fish, we demonstrate that the electrosensory space for prey detection has an unusual, omnidirectional shape. We compare this sensory volume with the animal's motor volume--the volume swept out by the body over selected time intervals and over the time it takes to come to a stop from typical hunting velocities. We find that the motor volume has a similar omnidirectional shape, which can be attributed to the fish's backward-swimming capabilities and body dynamics. We assessed the electrosensory space for prey detection by analyzing simulated changes in spiking activity of primary electrosensory afferents during empirically measured and synthetic prey capture trials. The animal's motor volume was reconstructed from video recordings of body motion during prey capture behavior. Our results suggest that in weakly electric fish, there is a close connection between the shape of the sensory and motor volumes. We consider three general spatial relationships between 3-D sensory and motor volumes in active and passive-sensing animals, and we examine hypotheses about these relationships in the context of the volumes we quantify for weakly electric fish. We propose that the ratio of the sensory volume to the motor volume provides insight into behavioral control strategies across all animals.

  7. Temperature analysis of induction motors using a hybrid thermal model with distributed heat sources

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S. C.; Pal, S. K.

    1998-06-01

    The article presents a hybrid thermal model for the accurate estimation of temperature distribution of induction motors. The developed model is a combination of lumped and distributed thermal parameters which are obtained from motor dimensions and other constants such as material density, specific heats, thermal conductivity, etc. The model is especially suited for the derating of induction motors operating under distorted and unbalanced supply condition. The model have been applied to a small (2hp, 415 V, 3-phase) cage rotor induction motor. The performance of the model is confirmed by experimental temperature data from the body and the conductor inside the slots of the motor.

  8. Tandem motors reduce well costs

    SciTech Connect

    Hooper, M.; Daigle, C.; Crowe, R.

    1995-10-01

    The new generation of tandem mud motors that recently appeared on the drilling scene is significantly affecting drilling efficiency worldwide. These motors provide drillers with increased horsepower at the bit, higher torque, and faster rates of penetration (ROP). With advanced engineering and more durable materials, motor life is being extended, thereby increasing the time between bit trips and reducing drilling costs. This article reviews the performance, design, and operation of these motors.

  9. Numerical Study on the Effect of Substrate Angle on Particle Impact Velocity and Normal Velocity Component in Cold Gas Dynamic Spraying Based on CFD

    NASA Astrophysics Data System (ADS)

    Yin, Shuo; Wang, Xiao-Fang; Li, Wen-Ya; Xu, Bao-Peng

    2010-12-01

    Numerical study was conducted to investigate the effect of substrate angle on particle impact velocity and normal velocity component in cold gas dynamic spraying by using three-dimensional models based on computational fluid dynamics. It was found that the substrate angle has significant effect on particle impact velocity and normal velocity component. With increasing the substrate angle, the bow shock strength becomes increasingly weak, which results in a gradual rise in particle impact velocity. The distribution of the impact velocity presents a linearly increase along the substrate centerline due to the existence of the substrate angle and the growth rate rises gradually with increasing the substrate angle. Furthermore, the normal velocity component reduces steeply with the increase in substrate angle, which may result in a sharp decrease in deposition efficiency. In addition, the study on the influence of procedure parameters showed that gas pressure, temperature, type, and particle size also play an important role in particle acceleration.

  10. Automated Motor Skills Training Optimized for Individual Differences.

    DTIC Science & Technology

    1980-11-01

    training. A general review of the researh effort as well as a .pecific discussion of the research conducted during 1 October 1979 to 󈧎 Septem~her P1...1977. I Savage, R. E., Williges, R. C., and Williges, B. H. Individual differences in motor skill training. Paper presented at the Sixth Psychology in...Paper presented at the Sixth Psychology in the DoD Symposium, April, 1979. Williges, R. C. and Williges, B. H. Automated motor skills training

  11. Control over band structure and tunneling in bilayer graphene induced by velocity engineering.

    PubMed

    Cheraghchi, Hosein; Adinehvand, Fatemeh

    2014-01-08

    The band structure and transport properties of massive Dirac fermions in bilayer graphene with velocity modulation in space are investigated in the presence of a previously created band gap. It is pointed out that velocity engineering may be considered as a factor to control the band gap of symmetry-broken bilayer graphene. The band gap is direct and independent of velocity value if the velocity modulated in two layers is set up equally. Otherwise, in the case of interlayer asymmetric velocity, not only is the band gap indirect, but also the electron-hole symmetry fails. This band gap is controllable by the ratio of the velocity modulated in the upper layer to the velocity modulated in the lower layer. In more detail, the shift of momentum from the conduction band edge to the valence band edge can be engineered by the gate bias and velocity ratio. A transfer matrix method is also elaborated to calculate the four-band coherent conductance through a velocity barrier possibly subjected to a gate bias. Electronic transport depends on the ratio of velocity modulated inside the barrier to that for surrounding regions. As a result, a quantum version of total internal reflection is observed for thick enough velocity barriers. Moreover, a transport gap originating from the applied gate bias is engineered by modulating the velocities of the carriers in the upper and lower layers.

  12. Effect of fuel concentration on cargo transport by a team of Kinesin motors

    NASA Astrophysics Data System (ADS)

    Takshak, Anjneya; Mishra, Nirvantosh; Kulkarni, Aditi; Kunwar, Ambarish

    2017-02-01

    Eukaryotic cells employ specialized proteins called molecular motors for transporting organelles and vesicles from one location to another in a regulated and directed manner. These molecular motors often work collectively in a team while transporting cargos. Molecular motors use cytoplasmic ATP as fuel, which is hydrolyzed to generate mechanical force. While the effect of ATP concentration on cargo transport by single Kinesin motor function is well understood, it is still unexplored, both theoretically and experimentally, how ATP concentration would affect cargo transport by a team of Kinesin motors. For instance, how does fuel concentration affect the travel distances and travel velocities of cargo? How cooperativity of Kinesin motors engaged on a cargo is affected by ATP concentration? To answer these questions, here we develop mechano-chemical models of cargo transport by a team of Kinesin motors. To develop these models we use experimentally-constrained mechano-chemical model of a single Kinesin motor as well as earlier developed mean-field and stochastic models of load sharing for cargo transport. Thus, our new models for cargo transport by a team of Kinesin motors include fuel concentration explicitly, which was not considered in earlier models. We make several interesting predictions which can be tested experimentally. For instance, the travel distances of cargos are very large at limited ATP concentrations in spite of very small travel velocity. Velocities of cargos driven by multiple Kinesin have a Michaelis-Menten dependence on ATP concentration. Similarly, cooperativity among the engaged Kinesin motors on the cargo shows a Michaelis-Menten type dependence, which attains a maximum value near physiological ATP concentrations. Our new results can be potentially useful in controlling artificial nano-molecular shuttles precisely for targeted delivery in various nano-technological applications.

  13. Motor Vehicle Theft. Special Report.

    ERIC Educational Resources Information Center

    Harlow, Caroline Wolf

    Thirteen years of data from the National Crime Survey were analyzed to examine the characteristics of motor vehicle theft, to identify trends during the past 13 years, and to determine who are most likely to be victims of motor vehicle theft. All motor vehicle thefts reported to the National Crime Survey from 1973 through 1985 were examined.…

  14. Speed control for synchronous motors

    NASA Technical Reports Server (NTRS)

    Packard, H.; Schott, J.

    1981-01-01

    Feedback circuit controls fluctuations in speed of synchronous ac motor. Voltage proportional to phase angle is developed by phase detector, rectified, amplified, compared to threshold, and reapplied positively or negatively to motor excitation circuit. Speed control reduces wow and flutter of audio turntables and tape recorders, and enhances hunting in gyroscope motors.

  15. Brushless direct-current motors

    NASA Technical Reports Server (NTRS)

    Bahm, E. J.

    1970-01-01

    Survey results are presented on the use of unconventional motor windings and switching sequences to optimize performance of brushless dc motors. A motor was built, each coil terminal having a separate, accessible lead. With the shaft and all electronics excluded, length and outside diameter measured 1.25 and 0.75 in., respectively.

  16. Motor Education: Educational Development Programs.

    ERIC Educational Resources Information Center

    Tansley, A. E.

    This booklet presents educational programs and activities focusing on motor skills for 5- to 9-year-old children and older children with learning problems. The premise of the activities is that the acquisition of motor skills is essential to basic learning. The role of language as a mediator and controller of motor development is emphasized. The…

  17. Multiple stage miniature stepping motor

    DOEpatents

    Niven, William A.; Shikany, S. David; Shira, Michael L.

    1981-01-01

    A stepping motor comprising a plurality of stages which may be selectively activated to effect stepping movement of the motor, and which are mounted along a common rotor shaft to achieve considerable reduction in motor size and minimum diameter, whereby sequential activation of the stages results in successive rotor steps with direction being determined by the particular activating sequence followed.

  18. Multisensor fusion for induction motor aging analysis and fault diagnosis

    NASA Astrophysics Data System (ADS)

    Erbay, Ali Seyfettin

    Induction motors are the most commonly used electrical drives, ranging in power from fractional horsepower to several thousand horsepowers. Several studies have been conducted to identify the cause of failure of induction motors in industrial applications. Recent activities indicate a focus towards building intelligence into the motors, so that a continuous on-line fault diagnosis and prognosis may be performed. The purpose of this research and development was to perform aging studies of three-phase, squirrel-cage induction motors; establish a database of mechanical, electrical and thermal measurements from load testing of the motors; develop a sensor-fusion method for on-line motor diagnosis; and use the accelerated aging models to extrapolate to the normal aging regimes. A new laboratory was established at The University of Tennessee to meet the goals of the project. The accelerated aging and motor performance tests constitute a unique database, containing information about the trend characteristics of measured signatures as a function of motor faults. The various measurements facilitate enhanced fault diagnosis of motors and may be effectively utilized to increase the reliability of decision making and for the development of life prediction techniques. One of these signatures is the use of Multi-Resolution Analysis (MRA) using wavelets. Using MRA in trending different frequency bands has revealed that higher frequencies show a characteristic increase when the condition of a bearing is in question. This study effectively showed that the use of MRA in vibration signatures can identify a thermal degradation or degradation via electrical charge of the bearing, whereas other failure mechanisms, such as winding insulation failure, do not exhibit such characteristics. A motor diagnostic system, called the Intelligent Motor Monitoring System (IMMS) was developed in this research. The IMMS integrated the various mechanical, electrical and thermal signatures, and

  19. Advanced Ultra-High Speed Motor for Drilling

    SciTech Connect

    Impact Technologies LLC; University of Texas at Arlington

    2007-03-31

    ,000 rpm for every 30.48 cm (12 inches) of power section. Operating conditions are 300 voltage AC at the motor leads. Power voltage losses in the cables/wirelines to the motor(s) are expected to be about 10% for 5000 feet carrying 2 amperes. Higher voltages and better insulators can lower these losses and carry more amperes. Cutting elements for such high tip velocities are currently not available, consequently these motors will not be built at this time. However, 7.62 cm (3 inch) OD, low speed, PMSM radial electric motors based on this project design are being built under a 2006 Oklahoma Center for the Advancement of Science and Technology 'proof of concept' grant.

  20. Effects of forward velocity on turbulent jet mixing noise

    NASA Technical Reports Server (NTRS)

    Plumblee, H. E., Jr. (Editor)

    1976-01-01

    Flight simulation experiments were conducted in an anechoic free jet facility over a broad range of model and free jet velocities. The resulting scaling laws were in close agreement with scaling laws derived from theoretical and semiempirical considerations. Additionally, measurements of the flow structure of jets were made in a wind tunnel by using a laser velocimeter. These tests were conducted to describe the effects of velocity ratio and jet exit Mach number on the development of a jet in a coflowing stream. These turbulence measurements and a simplified Lighthill radiation model were used in predicting the variation in radiated noise at 90 deg to the jet axis with velocity ratio. Finally, the influence of forward motion on flow-acoustic interactions was examined through a reinterpretation of the 'static' numerical solutions to the Lilley equation.