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Sample records for motor conduction velocity

  1. Axonal conduction velocity and force of single human motor units.

    PubMed

    Dengler, R; Stein, R B; Thomas, C K

    1988-02-01

    Tungsten microelectrodes of the type used for microneurography have been used to record motor units selectively from the first dorsal interosseous and abductor pollicis brevis muscles of normal subjects and patients who had had complete sections of the ulnar or median nerve. After determining the recruitment threshold and the twitch tension (spike-triggered averaging) of a single unit, its nerve was stimulated at the wrist and the elbow using surface electrodes. By adjusting the position of the surface electrode and the stimulus intensity and by using computerized subtraction of responses just above and below threshold for a given unit, the same motor unit could often be identified in response to stimulation at both sites and its conduction velocity determined. The twitch tension and recruitment threshold of the motor units were closely correlated with the conduction velocity of the motor axons in normal subjects. Preliminary data from patients suggests that this method should be applicable to patients with a number of neuromuscular disorders. PMID:3343989

  2. Somatosensory evoked potentials (SSEPs); sensory nerve conduction velocity (SNCV) and motor nerve conduction velocity (MNCV) in chronic renal failure.

    PubMed

    Makkar, R K; Kochar, D K

    1994-01-01

    Somatosensory evoked potentials, sensory and motor nerve conduction velocity were studied in 25 patients of chronic renal failure and the results were compared with 15 healthy persons. The values more than +/- 3 S.D. were considered abnormal. SNCV was reduced in 11/25 patients; average reduction being 18 m/s (highly significant, p < 0.001); MNCV was reduced in 11/25 patients, average reduction being 20 m/s (highly significant, p < 0.001). Both SNCV and MNCV in same person were reduced in 6/25 patients. In SSEP N9, N13 and N20 were delayed in almost all the patients (highly significant, p < 0.001). Amplitude of N20 and N13 were reduced in 1 and 4 patients respectively but amplitude of N9 was normal. Out of different IPLS, Ebw-N9 was delayed in 5/25 patients (p < 0.9, insignificant); N9-N13 was delayed in 8/25 patients (p < 0.001, highly significant); N13-N20 was delayed in 1/25 patients (p < 0.01, significant). The evidence of these neurophysiological abnormalities collectively suggest the presence of central-peripheral axonopathy in this disease. PMID:7956880

  3. Motor nerve conduction velocity (MCV) and lead content in sciatic nerve of lead-exposed rats

    SciTech Connect

    Maehara, N.; Uchino, E.; Terayama, K.; Ohno, H.; Yamamura, K.

    1986-07-01

    There have been many pathological and electrophysiological studies of peripheral nerves in inorganic lead intoxication. Peripheral nerve conduction velocity (NCV) has been used as an objective measure of the effects of lead on the peripheral nerve function and has been examined with blood lead content. There have been few reports on the changes in NCV related to lead content in the peripheral nerve tissue under lead poisoning. In the present study, the authors have examined motor nerve conduction velocity (MCV) of the tail by a non-invasive method and lead content of the peripheral nerve in lead-exposed rats. Furthermore, they have attempted to assess the relationship between these two parameters.

  4. Motor nerve conduction velocity is affected in segmental vitiligo lesional limbs.

    PubMed

    Zhou, Jun; Zhong, Zhenyu; Li, Jian; Fu, Wenwen

    2016-06-01

    To evaluate the effects of segmental vitiligo (SV) on nerve conduction velocity (NCV) in different nerves, we compared the patient's lesional side of their body to the contralateral normal side. The 106 participants were selected from outpatients visiting the dermatological clinics of Huashan Hospital, Fudan University, from November 2011 to March 2014. NCVs were measured on the limbs and the face, including both motor and sensory nerves. The parameters for NCVs included motor nerve conduction velocity (MCV) and its distal conduction latency, sensory nerve conduction velocity, sensory nerve action potentials amplitude, and compound muscle action potential amplitude. MCV on the limbs was compromised by SV state, which was significantly slower on the lesional side of the body compared with the normal contralateral side (P = 0.006). Furthermore, SV at the stable stage significantly impaired MCV compared with the SV at progressive stage. There was no significant difference in the other parameters of NCV between lesional and normal sides of the body. Compound muscle action potentials in the face did not differ between lesional and healthy sides. Motor nerves in the limbs were compromised by SV, particularly when the disease was at the stable stage. PMID:26916936

  5. 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

    2015-01-01

    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. PMID:26384112

  6. Motor and sensory ulnar nerve conduction velocities: effect of elbow position.

    PubMed

    Harding, C; Halar, E

    1983-05-01

    Ulnar motor and sensory nerve conduction velocities (NCV) were studied bilaterally in 20 able-bodied subjects for below elbow (BE) and across elbow (AE) segments to assess the effect of 4 different elbow positions on NCV (0 degrees, 45 degrees, 90 degrees, and 135 degrees). Although constant skin stimulation marker points were used, the AE segment length became progressively longer with increased elbow flexion. At 0 degrees flexion the AE segment motor NCV was found to be slower, and at 45 degrees it was found faster than the BE NCV. At each subsequent elbow flexion position (90 degrees and 135 degrees) there was an erroneous increase in motor and sensory NCV for the AE segments (p less than 0.01). This increase in AE NCV with elbow flexion was mostly due to stretching of skin over the flexed elbow. The nerve itself was observed in 4 cadaver specimens to slide distally with respect to the above elbow skin marker. Since 45 degrees elbow flexion was the position of least variation in motor NCV for AE and BE segments, this degree of elbow flexion appears to be optimum. From these measurements and from literature review neither short AE segment length (less than 10 cm) nor long AE segment length (greater than 15 cm) is optimum for measurement of AE NCV in the assessment of compressive neuropathy at the elbow. Short segments are subject to increased NCV variation while long segments may not detect pathological slowing of NCV only occurring over a short portion of the nerve. PMID:6847360

  7. Nerve conduction velocity

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003927.htm Nerve conduction velocity To use the sharing features on this page, please enable JavaScript. Nerve conduction velocity (NCV) is a test to see how ...

  8. 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. PMID:19165752

  9. 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.

  10. Nerve conduction velocity

    MedlinePlus

    Nerve conduction velocity (NCV) is a test to see how fast electrical signals move through a nerve. ... normal body temperature. Being too cold slows nerve conduction. Tell your doctor if you have a cardiac ...

  11. Longitudinal changes of nerve conduction velocity, distal motor latency, compound motor action potential duration, and skin temperature during prolonged exposure to cold in a climate chamber.

    PubMed

    Maetzler, Walter; Klenk, Jochen; Becker, Clemens; Zscheile, Julia; Gabor, Kai-Steffen; Lindemann, Ulrich

    2012-09-01

    Changes of nerve conduction velocity (NCV), distal motor latency (DML), compound motor action potential (CMAP) duration, and skin temperature with regard to cold have been investigated by use of ice packs or cold water baths, but not after cooling of environmental temperature which has higher ecological validity. The aim of this study was to investigate these parameters during cooled room temperature. NCV, DML, and CMAP duration of the common fibular nerve, and skin temperature were measured in 20 healthy young females during exposure to 15°C room temperature, coming from 25°C room. We found that NCV decreased and DML increased linearly during 45 min observation time, in contrast to CMAP duration and skin temperature which changes followed an exponential curve. To the best of our knowledge, this is the first study investigating changes of these parameters during exposure to environmental cold. The results may pilot some new hypotheses and studies on physiological and pathological changes of the peripheral nervous system and skin to environmental cold, e.g., in elderly with peripheral neuropathies. PMID:22510085

  12. Early co-administration of vitamin E acetate and methylcobalamin improves thermal hyperalgesia and motor nerve conduction velocity following sciatic nerve crush injury in rats.

    PubMed

    Morani, Aashish S; Bodhankar, Subhash L

    2010-01-01

    Our previous studies have shown that early administration of vitamin E acetate (50 mg/kg, ip (VEA)) and methylcobalamin (500 microg/kg, ip (MCA)) for 30 days improved conduction velocity and neuropathic pain behavior. Here, we evaluated the effect of early co-administration of VEA and MCA (MVE) on thermal hyperlagesia (TH) and motor nerve conduction velocity (MNCV) in rats with sciatic nerve crush injury (SNCI). Fifteen days post-surgery, a reduction in paw withdrawal latency (PWL) was observed in untreated (UNTR) rats. However, latency improved in MVE-treated animals, comparable to the placebo. On day 15, a decrease in MNCV was observed in the UNTR group of animals, and this effect was not observed for the MVE and placebo groups of animals. The results of this study indicate that early exposure to MVE attenuates the progression of TH and improves MNCV in rats with SNCI. PMID:20508297

  13. Gallic acid and exercise training improve motor function, nerve conduction velocity but not pain sense reflex after experimental sciatic nerve crush in male rats

    PubMed Central

    Hajimoradi, Maryam; Fazilati, Mohammad; Gharib-Naseri, Mohammad Kazem; Sarkaki, Alireza

    2015-01-01

    Objective: The aim of present study was to evaluate the effects of oral administration of gallic acid (GA) for 21 days alone and in combination with exercise on nerve conduction velocity and sensory and motor functions in rats with sciatic nerve crush. Materials and Methods: Seventy adult male Wistar rats (250-300 g) were divided randomly into 7 groups with 10 in each: 1) Control (Cont), 2) Crushed + Vehicle (Cr +Veh), 3-5) Crushed + gallic acid (Cr+GA) (50, 100, and 200 mg/kg/2 mL, orally), 6) Crushed + exercise (Cr+Exe), and 7) Crushed + exercise + effective dose of gallic acid (Cr+Exe +GA200) for 21 days. In order to establish an animal model of sciatic nerve crush, equivalent to 7 kg of force pressed on 2-3 mm of sciatic nerve for 30 s, three times with 30 s intervals. Pain sense reflex in hot plate, motor coordination in rotarod, and sciatic nerve conduction velocity (SNCV) in all groups were tested. Data were analyzed using one-way ANOVA followed by Tukey’s post hoc test and p<0.05 has assigned as the significant difference. Results: Pain threshold was increased significantly in untreated crushed rats while motor function and SNCV were decreased in all groups with nerve crush (p<0.05, p<0.01, p<0.001 vs. control). Pain reflex latency was not changed in treated groups. Motor coordination and SNCV were improved in groups Cr+GA200 and Cr+Exe + GA200 (p<0.05, p<0.01 vs. Cr+Veh). Conclusion: GA, dose-dependently, may have therapeutic potential to improve the peripheral nerve degeneration, which is most likely related, at least in part, to its antioxidant and therapeutic properties. PMID:26445710

  14. Effects of adenosine and adenosine A2A receptor agonist on motor nerve conduction velocity and nerve blood flow in experimental diabetic neuropathy.

    PubMed

    Kumar, Sokindra; Arun, K H S; Kaul, Chaman L; Sharma, Shyam S

    2005-01-01

    This study examined the effects of chronic administration of adenosine and CGS 21680 hydrochloride (adenosine A(2A) receptor agonist) on motor nerve conduction velocity (MNCV), nerve blood flow (NBF) and histology of sciatic nerve in animal model of diabetic neuropathy. Adenosinergic agents were administered for 2 weeks after 6 weeks of streptozotocin-induced (50 mg/kg i.p.) diabetes in male Sprague-Dawley rats. Significant reduction in sciatic MNCV and NBF were observed after 8 weeks in diabetic animals in comparison with control (non diabetic) rats. Adenosine (10 mg/kg, i.p.) significantly improved sciatic MNCV and NBF in diabetic rats. The protective effect of adenosine on MNCV and NBF was completely reversed by theophylline (50 mg/kg, i.p.), a non-selective adenosine receptor antagonist, suggesting that the adenosine effect was mediated via adenosinergic receptors. CGS 21680 (0.1 mg/kg, i.p.) significantly improved NBF; however, MNCV was not significantly improved in diabetic rats. At a dose of 1 mg/kg, neither MNCV nor NBF was improved by CGS 21680 in diabetic rats. ZM 241385 (adenosine A(2A) receptor antagonist) prevented the effect of CGS 21680 (0.1 mg/kg, i.p.). Histological changes observed in sciatic nerve were partially improved by the adenosinergic agents in diabetic rats. Results of the present study, suggest the potential of adenosinergic agents in the therapy of diabetic neuropathy. PMID:15829161

  15. Nerve conduction velocity in hypertensive patients.

    PubMed

    Halar, E M; Stewart, D T; Venkatesh, B; Chrissian, S A

    1978-01-01

    Due to conflicting reports in the literature regarding nerve conduction velocities (NCVs) in hypertensives, peroneal and sural NCVs and facial nerve conduction latencies were studied in 30 hypertensives and in 30 controls. An improved technique of NCV measurement was used. Twenty-one of the hypertensives were retested after five weeks, and five of them were tested for motor and sensory NCVs of the median nerve during a short period of partial occlusion of blood flow in the arm. No changes were found that could be related to blood pressure, duration of hypertension, eyeground changes, or partial restriction of blood flow. PMID:619818

  16. Effect of high-frequency repetitive transcranial magnetic stimulation on motor cortical excitability and sensory nerve conduction velocity in subacute-stage incomplete spinal cord injury patients.

    PubMed

    Cha, Hyun Gyu; Ji, Sang-Goo; Kim, Myoung-Kwon

    2016-07-01

    [Purpose] The aim of the present study was to determine whether repetitive transcranial magnetic stimulation can improve sensory recovery of the lower extremities in subacute-stage spinal cord injury patients. [Subjects and Methods] This study was conducted on 20 subjects with diagnosed paraplegia due to spinal cord injury. These 20 subjects were allocated to an experimental group of 10 subjects that underwent active repetitive transcranial magnetic stimulation or to a control group of 10 subjects that underwent sham repetitive transcranial magnetic stimulation. The SCI patients in the experimental group underwent active repetitive transcranial magnetic stimulation and conventional rehabilitation therapy, whereas the spinal cord injury patients in the control group underwent sham repetitive transcranial magnetic stimulation and conventional rehabilitation therapy. Participants in both groups received therapy five days per week for six-weeks. Latency, amplitude, and sensory nerve conduction velocity were assessed before and after the six week therapy period. [Results] A significant intergroup difference was observed for posttreatment velocity gains, but no significant intergroup difference was observed for amplitude or latency. [Conclusion] repetitive transcranial magnetic stimulation may be improve sensory recovery of the lower extremities in subacute-stage spinal cord injury patients. PMID:27512251

  17. Effect of high-frequency repetitive transcranial magnetic stimulation on motor cortical excitability and sensory nerve conduction velocity in subacute-stage incomplete spinal cord injury patients

    PubMed Central

    Cha, Hyun Gyu; Ji, Sang-Goo; Kim, Myoung-Kwon

    2016-01-01

    [Purpose] The aim of the present study was to determine whether repetitive transcranial magnetic stimulation can improve sensory recovery of the lower extremities in subacute-stage spinal cord injury patients. [Subjects and Methods] This study was conducted on 20 subjects with diagnosed paraplegia due to spinal cord injury. These 20 subjects were allocated to an experimental group of 10 subjects that underwent active repetitive transcranial magnetic stimulation or to a control group of 10 subjects that underwent sham repetitive transcranial magnetic stimulation. The SCI patients in the experimental group underwent active repetitive transcranial magnetic stimulation and conventional rehabilitation therapy, whereas the spinal cord injury patients in the control group underwent sham repetitive transcranial magnetic stimulation and conventional rehabilitation therapy. Participants in both groups received therapy five days per week for six-weeks. Latency, amplitude, and sensory nerve conduction velocity were assessed before and after the six week therapy period. [Results] A significant intergroup difference was observed for posttreatment velocity gains, but no significant intergroup difference was observed for amplitude or latency. [Conclusion] repetitive transcranial magnetic stimulation may be improve sensory recovery of the lower extremities in subacute-stage spinal cord injury patients. PMID:27512251

  18. Aldose reductase inhibition improves nerve conduction velocity in diabetic patients.

    PubMed

    Judzewitsch, R G; Jaspan, J B; Polonsky, K S; Weinberg, C R; Halter, J B; Halar, E; Pfeifer, M A; Vukadinovic, C; Bernstein, L; Schneider, M; Liang, K Y; Gabbay, K H; Rubenstein, A H; Porte, D

    1983-01-20

    To assess the potential role of polyol-pathway activity in diabetic neuropathy, we measured the effects of sorbinil--a potent inhibitor of the key polyol-pathway enzyme aldose reductase--on nerve conduction velocity in 39 stable diabetics in a randomized, double-blind, cross-over trial. During nine weeks of treatment with sorbinil (250 mg per day), nerve conduction velocity was greater than during a nine-week placebo period for all three nerves tested: the peroneal motor nerve (mean increase [+/- S.E.M.], 0.70 +/- 0.24 m per second, P less than 0.008), the median motor nerve (mean increase, 0.66 +/- 0.27, P less than 0.005), and the median sensory nerve (mean increase, 1.16 +/- 0.50, P less than 0.035). Conduction velocity for all three nerves declined significantly within three weeks after cessation of the drug. These effects of sorbinil were not related to glycemic control, which was constant during the study. Although the effect of sorbinil in improving nerve conduction velocity in diabetics was small, the findings suggest that polyol-pathway activity contributes to slowed nerve conduction in diabetics. The clinical applicability of these observations remains to be determined, but they encourage further exploration of this approach to the treatment or prevention of diabetic neuropathy. PMID:6401351

  19. Nerve conduction velocity measurements: improved accuracy using superimposed response waves.

    PubMed

    Halar, E M; Venkatesh, B

    1976-10-01

    A new procedure of serial motor nerve conduction velocity (NCV) measurements with the use of "superimposed response waves" technique (or double stimulus technique) was performed on 29 normal subjects. Six peripheral nerves were tested once a week for four to six weeks. A total of 760 NCV measurements were thus obtained to try to assess the magnitude of error in serial NCV testings. With the double stimulus technique employed, a significant reduction in variations of serial NCV measurements was found. The overall standard deviation of four to six consecutive NCV measurements in the 34 subjects was 1.3 meters per second with a coefficient of variation of 2.4%. These findings obtained with the double stimulus technique have proven to be approximately three times more accurate than results obtained by investigators who studied nerve conduction velocity measurement variation with single stimulus standard NCV testing techniques. PMID:184754

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. Axon diameters and conduction velocities in the macaque pyramidal tract

    PubMed Central

    Firmin, L.; Field, P.; Maier, M. A.; Kraskov, A.; Kirkwood, P. A.; Nakajima, K.; Lemon, R. N.

    2014-01-01

    Small axons far outnumber larger fibers in the corticospinal tract, but the function of these small axons remains poorly understood. This is because they are difficult to identify, and therefore their physiology remains obscure. To assess the extent of the mismatch between anatomic and physiological measures, we compared conduction time and velocity in a large number of macaque corticospinal neurons with the distribution of axon diameters at the level of the medullary pyramid, using both light and electron microscopy. At the electron microscopic level, a total of 4,172 axons were sampled from 2 adult male macaque monkeys. We confirmed that there were virtually no unmyelinated fibers in the pyramidal tract. About 14% of pyramidal tract axons had a diameter smaller than 0.50 μm (including myelin sheath), most of these remaining undetected using light microscopy, and 52% were smaller than 1 μm. In the electrophysiological study, we determined the distribution of antidromic latencies of pyramidal tract neurons, recorded in primary motor cortex, ventral premotor cortex, and supplementary motor area and identified by pyramidal tract stimulation (799 pyramidal tract neurons, 7 adult awake macaques) or orthodromically from corticospinal axons recorded at the mid-cervical spinal level (192 axons, 5 adult anesthetized macaques). The distribution of antidromic and orthodromic latencies of corticospinal neurons was strongly biased toward those with large, fast-conducting axons. Axons smaller than 3 μm and with a conduction velocity below 18 m/s were grossly underrepresented in our electrophysiological recordings, and those below 1 μm (6 m/s) were probably not represented at all. The identity, location, and function of the majority of corticospinal neurons with small, slowly conducting axons remains unknown. PMID:24872533

  6. The non-linear relationship between nerve conduction velocity and skin temperature.

    PubMed Central

    Todnem, K; Knudsen, G; Riise, T; Nyland, H; Aarli, J A

    1989-01-01

    Median motor and sensory nerves were examined in 20 healthy subjects. Superficial stimulating and recording electrodes were used, and the nerves were examined at natural skin temperature, after cooling and after heating of the arm. The conduction velocity for the fastest and slow conducting sensory fibres (temperature range 17-37 degrees C), and for the fastest conducting motor fibres (temperature range 19-38 degrees C) increased non-linearly with increase in skin temperature. Similarly, distal motor latencies increased non-linearly with decrease in skin temperature. The effect of temperature was most pronounced in the low temperature range, and change in conduction velocity per degree centigrade was reduced toward higher skin temperature. Sensory nerve response duration increased linearly with decline in skin temperature. Sensory and motor amplitude did not show any significant relation to skin temperature. PMID:2738592

  7. 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.

  8. Changes in the axonal conduction velocity of pyramidal tract neurons in the aged cat.

    PubMed

    Xi, M C; Liu, R H; Engelhardt, J K; Morales, F R; Chase, M H

    1999-01-01

    The present study was undertaken to determine whether age-dependent changes in axonal conduction velocity occur in pyramidal tract neurons. A total of 260 and 254 pyramidal tract neurons were recorded extracellularly in the motor cortex of adult control and aged cats, respectively. These cells were activated antidromically by electrical stimulation of the medullary pyramidal tract. Fast- and slow-conducting neurons were identified according to their axonal conduction velocity in both control and aged cats. While 51% of pyramidal tract neurons recorded in the control cats were fast conducting (conduction velocity greater than 20 m/s), only 26% of pyramidal tract neurons in the aged cats were fast conducting. There was a 43% decrease in the median conduction velocity for the entire population of pyramidal tract neurons in aged cats when compared with that of pyramidal tract neurons in the control cats (P < 0.001, Mann-Whitney U-test). A linear relationship between the spike duration of pyramidal tract neurons and their antidromic latency was present in both control and aged cats. However, the regression slope was significantly reduced in aged cats. This reduction was due to the appearance of a group of pyramidal tract neurons with relatively shorter spike durations but slower axonal conduction velocities in the aged cat. Sample intracellular data confirmed the above results. These observations form the basis for the following conclusions: (i) there is a decrease in median conduction velocity of pyramidal tract neurons in aged cats; (ii) the reduction in the axonal conduction velocity of pyramidal tract neurons in aged cats is due, in part, to fibers that previously belonged to the fast-conducting group and now conduct at slower velocity. PMID:10392844

  9. A point mutation in the microtubule binding region of the Ncd motor protein reduces motor velocity.

    PubMed Central

    Moore, J D; Song, H; Endow, S A

    1996-01-01

    Non-claret disjunctional (Ncd) is a kinesin-related microtubule motor protein in Drosophila that functions in meiotic spindle assembly in oocytes and spindle pole maintenance in early embryos. The partial loss-of-function mutant ncdD retains mitotic, but not meiotic, function. The predicted NcdD mutant protein contains a V556-->F mutation in the putative microtubule binding region of the Ncd motor domain. Here we report an analysis of the properties of recombinant Ncd and NcdD proteins. A GST-NcdD fusion protein translocated microtubules approximately 10-fold more slowly than the corresponding wild-type protein in gliding assays. The maximum microtubule-stimulated ATPase activity of an NcdD motor domain protein was reduced approximately 3-fold and an approximately 3-fold greater concentration of microtubules was required for half-maximal stimulation of ATPase activity, compared with the corresponding wild-type protein. The Km for ATP and basal rate of ATP turnover were, in contrast, similar for the NcdD mutant and wild-type Ncd motor domain proteins. Pelleting assays demonstrated that the binding of the mutant NcdD motor protein to microtubules was reduced in the absence of nucleotide, relative to wild-type. The reduced velocity of NcdD translocation on microtubules is therefore correlated with reductions in microtubule-stimulated ATPase activity and affinity of the mutant motor for microtubules. The characteristics of the NcdD motor explain its meiotic loss of function, and are consistent with partial motor activity of Ncd being sufficient for its mitotic, but not its meiotic, role. Images PMID:8670831

  10. SPECIES SPECIFICITY OF GIANT NERVE FIBER CONDUCTION VELOCITY IN OLIGOCHAETES

    EPA Science Inventory

    Giant nerve fiber conduction velocities were studied using noninvasive electrophysiological recording techniques in adults from 12 species of oligochaetes, representing five different families. Two separate and stereotyped all-or-none response patterns to tactile stimulation (cor...

  11. Peroneal nerve conduction velocity: the importance of temperature correction.

    PubMed

    Halar, E M; DeLisa, J A; Brozovich, F V

    1981-09-01

    The relationship between skin surface temperature, near nerve temperature and nerve conduction velocity (NCV) of the peroneal nerve was studied in normal and diabetic subjects to determine a peroneal NCV-treatment correction factor and to investigate whether temperature correction of NCV reduces its variability. Twenty normal subjects (age 21 to 72 years, mean 44, SD 17) were tested for peroneal NCV, skin and near nerve temperatures bilaterally at ambient temperature (mean 26.6C). Tests were repeated after cooling the lower extremity to a skin temperature of 26C, and at skin temperatures of 28 and 29C as the legs were allowed to gradually warm. An additional 20 normal and 20 diabetic subjects were tested weekly at ambient temperature for peroneal NCV and skin temperature, measured at 15cm above the lateral malleolus. The results showed a linear relationship between skin temperature, near nerve temperature and peroneal NCV (p less than 0.001). Peroneal NCV was altered 2.0 meters per second per degree (C) change in skin and near nerve temperature (p less than 0.001). When using our formula, peroneal motor NCV corrected = 2.0 [32 - skin temp(C)] + NCV (m/sec), for correction of peroneal NCV to a standard skin temperature of 32C, it was found that temperature corrected NCV were less variable (p less than 0.05) than noncorrected NCV in the same diabetic subjects. These results indicate that temperature corrected NCV should be calculated routinely during clinical NCV examinations of patients with peripheral neuropathies. PMID:7283685

  12. 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

  13. Fixed Velocity Characteristics for an Electrical Vehicle with the New High-Efficiency Motor

    NASA Astrophysics Data System (ADS)

    Kousaka, Takuji; Matsumoto, Yukihiro; Harada, Taisuke; Abe, Minoru

    Since d-c compound motor have wide industrial applications, theoretical and experimental research in such systems are assumed to be special importance. In previous work, we studied a new d-c compound motor which is suitable for the electronic vehicle and bicycle. This paper provides the fixed velocity characteristics for an electrical vehicle with the new high-efficiency motor. Experimental results show that the electric vehicle with new compund motor is more effective than the conventional one.

  14. Multifocal motor neuropathy with conduction block: a study of 24 patients.

    PubMed Central

    Bouche, P; Moulonguet, A; Younes-Chennoufi, A B; Adams, D; Baumann, N; Meininger, V; Léger, J M; Said, G

    1995-01-01

    Twenty four patients with pure motor neuropathy are reported. The chronic motor involvement associated with fasciculations and cramps, mainly in the arms, led, in most patients, to an initial diagnosis of motor neuron disease. In some patients (nine of 24), there was no appreciable muscle atrophy. Tendon reflexes were often absent or weak. The finding of persistent multifocal conduction block confined to motor nerve fibres raises questions about the nature and the importance of this syndrome. Segmental reduction of motor conduction velocity occurred at the site of the block, but significant slowing of motor nerve conduction was not found outside this site. The response to intravenous IVIg treatment seems to be correlated with the absence of amyotrophy. Patients with little or no amyotrophy had an initial and sustained response to IVIg, and did not develop amyotrophy during the follow up study. They could be considered to have a variant of chronic inflammatory demyelinating polyneuropathy. Patients with pronounced amyotrophy independent of the disease duration did not respond as well to IVIg treatment, suggesting the existence of a distinct entity. Among the patients treated about two thirds who had an initial good response to IVIg had high or significant antiganglioside GM1 (anti-GM1) antibody titres, but there was no correlation between the high titres before treatment and long lasting response to IVIg treatment. Images PMID:7608707

  15. 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

  16. 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.

  17. 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.

  18. Comparison of umbo velocity in air- and bone-conduction.

    PubMed

    Röösli, Christof; Chhan, David; Halpin, Christopher; Rosowski, John J

    2012-08-01

    This study investigates the ossicular motion produced by bone-conducted (BC) sound in live human ears. Laser Doppler vibrometry was used to measure air conduction (AC)- and BC-induced umbo velocity (V(U)) in both ears of 10 subjects, 20 ears total. Sound pressure in the ear canal (P(EC)) was measured simultaneously. For air conduction, V(U) at standard hearing threshold level was calculated. For BC, ΔV was defined as the difference between V(U) and the tympanic ring velocity (an estimate of the skull velocity measured in the ear canal). ΔV and P(EC) at BC standard hearing threshold were calculated. ΔV at standard BC threshold was significantly smaller than V(U) at standard AC threshold between 500 Hz and 2000 Hz. Ear canal pressure at BC threshold tended to be smaller than for AC below 3000 Hz (with significant differences at 1000 Hz and 2000 Hz). Our results are most consistent with inertia of the ossicles and cochlear fluid driving BC hearing below 500 Hz, but with other mechanisms playing a significant role at higher frequencies. Sound radiated into the external ear canal might contribute to BC hearing at 3000 Hz and above. PMID:22609771

  19. Effects of IDPN-induced axonal swellings on conduction in motor nerve fibers.

    PubMed

    Stanley, E F; Griffin, J W; Fahnestock, K E

    1985-07-01

    Paranodal demyelination produces a reduction of conduction velocity and conduction block. The relative proportions of these changes appear to vary among different demyelinating disorders. In this study we have examined the effects on conduction of paranodal demyelination produced by giant axonal swellings. The axonal swellings were induced in rats by administration of beta, beta'-iminodipropionitrile (IDPN). In this experimental model synchronous axonal swellings occur in the proximal region of virtually every alpha-motorneuron without evidence of segmental demyelination or fiber loss. Conduction across the motor neuron was evaluated by two methods: a monosynaptic reflex pathway and intracellular recording from single motor neurons. Increases in the delay across the central region of the monosynaptic reflex pathway began between 2 and 4 days after toxin administration. Intracellular studies confirmed that the slowing occurred across the proximal regions of the motor axons; more distal regions of the motor axons were unaffected. The substantial reduction in conduction velocity over the swollen segment occurs with only moderate evidence of conduction block, as assayed by a reduction in the H-reflex/M-response amplitude ratio. Parallel morphological studies showed that in the enlarged fibers the myelin terminal loops maintained contact with the axon but were displaced from the paranodal region into the internode. The appearance of this "passive" paranodal demyelination correlated closely with the increase in conduction delay. We suggest that the contact maintained by the displaced myelin terminal loops with the axolemma allows saltatory conduction to continue, and explains the paucity of conduction block in this model despite the prominent conduction slowing. PMID:2993531

  20. 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

    2016-08-01

    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. PMID:27414063

  1. Scaling properties of conduction velocity in heterogeneous excitable media

    NASA Astrophysics Data System (ADS)

    Shajahan, T. K.; Borek, Bartłomiej; Shrier, Alvin; Glass, Leon

    2011-10-01

    Waves of excitation through excitable media, such as cardiac tissue, can propagate as plane waves or break up to form reentrant spiral waves. In diseased hearts reentrant waves can be associated with fatal cardiac arrhythmias. In this paper we investigate the conditions that lead to wave break, reentry, and propagation failure in mathematical models of heterogeneous excitable media. Two types of heterogeneities are considered: sinks are regions in space in which the voltage is fixed at its rest value, and breaks are nonconducting regions with no-flux boundary conditions. We find that randomly distributed heterogeneities in the medium have a decremental effect on the velocity, and above a critical density of such heterogeneities the conduction fails. Using numerical and analytical methods we derive the general relationship among the conduction velocity, density of heterogeneities, diffusion coefficient, and the rise time of the excitation in both two and three dimensions. This work helps us understand the factors leading to reduced propagation velocity and the formation of spiral waves in heterogeneous excitable media.

  2. 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

  3. 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.

  4. 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.

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

    PubMed

    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

  6. 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

  7. Conduction velocity along muscle fibers in situ in Duchenne muscular dystrophy.

    PubMed

    Cruz Martinez, A; Lopez Terradas, J M

    1990-07-01

    The muscle fibers of the biceps brachii muscle were stimulated distally with low voltage by means of two monopolar needles in 14 boys with Duchenne muscular dystrophy (DD). The electric activity was recorded proximally by means of a SFEMG electrode. The mean conduction velocity of 508 muscle fibers in situ (MFCV) calculated with this method shows that MFCV in DD patients (2.38 +/- .94 m/sec) is significantly slower than in 20 control children of the same age (3.24 +/- .53 m/sec). The distribution frequency of MFCV in all fibers tested in healthy children shows a Gaussian distribution (mode = 3.2 m/sec). In DD patients the distribution frequency is bimodal with spikes at 1.2 and 2.4 m/sec. Significant decrease in minimum propagation velocity and increased SD values were other striking results in patients with DD. Slowing and large variation in MFCV were significantly correlated with some findings in a coaxial needle electromyogram, such as long polyphasics and motor unit potentials followed by satellites. Satellites might arise from atrophic muscle fibers with slow conduction velocity. The results of MFCV were supported by the pathologic findings in DD subjects. The reported method for MFCV in situ is reliable and easy to apply in children, has merit for testing the size and function of muscle fiber, and helps to explain some electropathologic features in DD patients. PMID:2164370

  8. Physical activity: its influence on nerve conduction velocity.

    PubMed

    Halar, E M; Hammond, M C; Dirks, S

    1985-09-01

    In a group of 40 healthy subjects, distal and proximal latencies of the median, tibial, and peroneal motor, and sural sensory nerves and their respective skin surface temperatures (Tsk) were measured before and after walking or bicycling. The baseline tests were performed 30 minutes after resting in a constant room temperature of 24C. The ambulation or bicycling task was continued for 30 minutes at a constant rate. Postactivity tests were performed within 30 minutes and between 45 to 60 minutes after termination of activity. Another test was done 75 to 90 minutes after bicycle exercise. After walking, there was a significant increase in Tsk in all lower extremity nerves tested (p less than 0.01). The increases were accompanied by faster distal and proximal latencies in both testing periods (p less than 0.01). Median nerve Tsk, distal and proximal latencies did not differ significantly from baseline values initially, but 45 minutes after walking Tsk was elevated and proximal latency had become faster (p less than 0.01). Following bicycling, lower extremity Tsk was significantly reduced over tibial, peroneal, and sural nerves by the third testing period (p less than 0.01) but only sural latencies were significantly prolonged (p less than 0.05) by this time. In the upper extremities median Tsk was significantly elevated and distal latency had become significantly faster 45 minutes after bicycling. Our data suggest that activity significantly influences nerve conduction latency results due to tissue temperature alteration. In addition, 30 minutes of rest after activity may not be sufficient time for the lower extremity temperatures to become stable. PMID:4038026

  9. 49 CFR 242.111 - Prior safety conduct as motor vehicle operator.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Prior safety conduct as motor vehicle operator... CONDUCTORS Program and Eligibility Requirements § 242.111 Prior safety conduct as motor vehicle operator. (a... prior conduct as a motor vehicle operator. (c) A railroad shall initially certify a person as...

  10. Determinants of myocardial conduction velocity: implications for arrhythmogenesis

    PubMed Central

    King, James H.; Huang, Christopher L.-H.; Fraser, James A.

    2013-01-01

    Slowed myocardial conduction velocity (θ) is associated with an increased risk of re-entrant excitation, predisposing to cardiac arrhythmia. θ is determined by the ion channel and physical properties of cardiac myocytes and by their interconnections. Thus, θ is closely related to the maximum rate of action potential (AP) depolarization [(dV/dt)max], as determined by the fast Na+ current (INa); the axial resistance (ra) to local circuit current flow between cells; their membrane capacitances (cm); and to the geometrical relationship between successive myocytes within cardiac tissue. These determinants are altered by a wide range of pathophysiological conditions. Firstly, INa is reduced by the impaired Na+ channel function that arises clinically during heart failure, ischemia, tachycardia, and following treatment with class I antiarrhythmic drugs. Such reductions also arise as a consequence of mutations in SCN5A such as those occurring in Lenègre disease, Brugada syndrome (BrS), sick sinus syndrome, and atrial fibrillation (AF). Secondly, ra, may be increased due to gap junction decoupling following ischemia, ventricular hypertrophy, and heart failure, or as a result of mutations in CJA5 found in idiopathic AF and atrial standstill. Finally, either ra or cm could potentially be altered by fibrotic change through the resultant decoupling of myocyte–myocyte connections and coupling of myocytes with fibroblasts. Such changes are observed in myocardial infarction and cardiomyopathy or following mutations in MHC403 and SCN5A resulting in hypertrophic cardiomyopathy (HCM) or Lenègre disease, respectively. This review defines and quantifies the determinants of θ and summarizes experimental evidence that links changes in these determinants with reduced myocardial θ and arrhythmogenesis. It thereby identifies the diverse pathophysiological conditions in which abnormal θ may contribute to arrhythmia. PMID:23825462

  11. Neurotransmissional, structural, and conduction velocity changes in cerebral ganglions of Lumbricus terrestris on exposure to acrylamide.

    PubMed

    Subaraja, Mamangam; Vanisree, A J

    2016-09-01

    Acrylamide (ACR), an environmental toxin though being investigated for decades, remains an enigma with respect to its mechanism/site of actions. We aim to explicate the changes in cerebral ganglions and giant fibers along with the behavior of worms on ACR intoxication (3.5-17.5 mg/mL of medium/7 days). Neurotransmitter analysis revealed increased levels of excitatory glutamate and inhibitory gamma amino butyrate with reduced levels of dopamine, serotonin, melatonin, and epinephrine (p < 0.001). Scanning electron microscopy showed architectural changes in cerebral ganglions at 3.5 mg/mL/ACR. The learning behavior as evidenced by Pavlovian and maze tests was also altered well at 3.5 mg/mL of ACR. Electrophysiological assessment showed a reduction in conduction velocity of the medial and lateral giant nerve fibers. We speculate that the observed dose/time-dependent changes in neurotransmission, neurosecretion, and conduction velocity on ACR intoxication at 17.5 mg/ml, possibly, could be due to its effect on nerve fibers governing motor functions. The bioaccumulation factor in the range of 0.38-0.99 mg/g of ACR causes a detrimental impact on giant fibers affecting behavior of worm. The observations made using the simple invertebrate model implicate that the cerebral ganglionic variations in the worms may be useful to appreciate the pathology of the neurological diseases which involve motor neuron dysfunction, esp where the availability of brain samples from the victims are scarce. PMID:27215980

  12. A new heat propagation velocity prevails over Brownian particle velocities in determining the thermal conductivities of nanofluids

    PubMed Central

    2011-01-01

    An alternative insight is presented concerning heat propagation velocity scales in predicting the effective thermal conductivities of nanofluids. The widely applied Brownian particle velocities in published literature are often found too slow to describe the relatively higher nanofluid conductivities. In contrast, the present model proposes a faster heat transfer velocity at the same order as the speed of sound, rooted in a modified kinetic principle. In addition, this model accounts for both nanoparticle heat dissipation as well as coagulation effects. This novel model of effective thermal conductivities of nanofluids agrees well with an extended range of experimental data. PMID:21711892

  13. Ensemble velocity of non-processive molecular motors with multiple chemical states

    PubMed Central

    Vilfan, Andrej

    2014-01-01

    We study the ensemble velocity of non-processive motor proteins, described with multiple chemical states. In particular, we discuss the velocity as a function of ATP concentration. Even a simple model which neglects the strain dependence of transition rates, reverse transition rates and nonlinearities in the elasticity can show interesting functional dependencies, which deviate significantly from the frequently assumed Michaelis–Menten form. We discuss how the order of events in the duty cycle can be inferred from the measured dependence. The model also predicts the possibility of velocity reversal at a certain ATP concentration if the duty cycle contains several conformational changes of opposite directionalities. PMID:25485083

  14. 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

  15. 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.

  16. Ulnar nerve motor conduction to the first dorsal interosseous muscle.

    PubMed

    Prahlow, Nathan D; Buschbacher, Ralph M

    2006-01-01

    The ulnar motor study to the abductor digiti minimi (ADM) is commonly performed, but does not test the terminal deep palmar branch of the ulnar nerve. Although damage to the ulnar nerve most often occurs at the elbow, the damage may occur elsewhere along the course of the nerve, including damage to the deep palmar branch. Ulnar conduction studies of the deep branch have been performed with recording from the first dorsal interosseous (FDI) muscle. These studies have used differing methodologies and were mostly limited by small sample size. The aim of this study was to develop a normative database for ulnar nerve conduction to the FDI. A new method of recording from the FDI was developed for this study. It utilizes recording with the active electrode over the dorsal first web space, with the reference electrode placed at the fifth metacarpophalangeal joint. This technique reliably yields negative takeoff measurements. An additional comparison was made between ulnar motor latency with recording at the ADM and with recording at the FDI. For this study, 199 subjects with no risk factors for neuropathy were tested. The latency, amplitude, area, and duration were recorded. The upper limit of normal (ULN) was defined as the 97th percentile of observed values. The lower limit of normal (LLN) was defined as the 3rd percentile of observed values. For the FDI, mean latency was 3.8 +/- 0.5 ms, with a ULN of 4.7 ms for males, 4.4 ms for females, and 4.6 ms for all subjects. Mean amplitude was 15.8 +/- 4.9 mV, with a LLN of 5.1 for all subjects. Side-to-side differences in latency to the FDI, from dominant to nondominant hands, was -0.1 +/- 0.4 ms, with a ULN of 0.8 ms. For the amplitude, up to a 52% decrease from side to side was normal. For the same-limb comparison of the FDI and ADM, the mean latency difference was 0.6 +/- 0.4 ms, with a ULN increase of 1.3 ms for latency to the ADM versus the FDI. PMID:17206927

  17. 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.

  18. The relationship between motor recovery and gait velocity during dual tasks in patients with chronic stroke.

    PubMed

    Lee, Kyoung Bo; Kim, Jang Hwan; Lee, Kang Sung

    2015-04-01

    [Purpose] The aims of this study were to identify the relationship between motor recovery and gait velocity during dual tasks in patients with chronic stroke and determine automatic gait ability following stroke. [Subjects and Methods] Thirty-three outpatients and twelve healthy subjects participated in a cross-sectional assessment. Community ambulation was assessed using a self-administered questionnaire. Outcome measures included the Motricity index, Berg Balance Scale, and gait speed under three conditions (self-paced ambulation for 10 m, ambulation while performing dual cognitive tasks, and ambulation while performing dual manual tasks). Gait automaticity was calculated. [Results] No significant differences were observed for muscle strength or balance between the limited community ambulation and the community ambulation groups. However, a significant difference in gait velocity was observed between the groups under the three conditions. In particular, a significant difference was detected only in the limited community ambulation group depending on the level of motor function recovery during cognitive and manual dual task ambulation. Additionally, we revealed that the community ambulation group had a lower level of gait automaticity compared with that in the normal group. [Conclusion] Our results show the influence of motor recovery on the change in gait velocity depending on the task if a patient is limitedly ambulatory. We revealed that community ambulators did not have a sufficient level of gait automaticity. PMID:25995582

  19. The relationship between motor recovery and gait velocity during dual tasks in patients with chronic stroke

    PubMed Central

    Lee, Kyoung Bo; Kim, Jang Hwan; Lee, Kang Sung

    2015-01-01

    [Purpose] The aims of this study were to identify the relationship between motor recovery and gait velocity during dual tasks in patients with chronic stroke and determine automatic gait ability following stroke. [Subjects and Methods] Thirty-three outpatients and twelve healthy subjects participated in a cross-sectional assessment. Community ambulation was assessed using a self-administered questionnaire. Outcome measures included the Motricity index, Berg Balance Scale, and gait speed under three conditions (self-paced ambulation for 10 m, ambulation while performing dual cognitive tasks, and ambulation while performing dual manual tasks). Gait automaticity was calculated. [Results] No significant differences were observed for muscle strength or balance between the limited community ambulation and the community ambulation groups. However, a significant difference in gait velocity was observed between the groups under the three conditions. In particular, a significant difference was detected only in the limited community ambulation group depending on the level of motor function recovery during cognitive and manual dual task ambulation. Additionally, we revealed that the community ambulation group had a lower level of gait automaticity compared with that in the normal group. [Conclusion] Our results show the influence of motor recovery on the change in gait velocity depending on the task if a patient is limitedly ambulatory. We revealed that community ambulators did not have a sufficient level of gait automaticity. PMID:25995582

  20. 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.

  1. 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. PMID:27564000

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

    PubMed

    McGill, Kevin C; Lateva, Zoia C

    2011-09-01

    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

  3. 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

  4. 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.

  5. Muscle fiber conduction velocity in the diagnosis of sporadic hypokalemic periodic paralysis.

    PubMed

    Brouwer, O F; Zwarts, M J; Links, T P; Wintzen, A R

    1992-01-01

    A 6-year-old girl presented with episodes of profound muscle weakness since the age of 2 years. On the basis of decreased ictal serum potassium level and lack of metabolic disorder, primary hypokalemic periodic paralysis (HPP) was diagnosed. Both parents and 3 sibs were unaffected clinically. In all of them asymptomatic heterozygosity was very unlikely by the finding of normal muscle fiber conduction velocities, whereas in the patient interictal muscle fiber conduction velocity was lowered. Determination of muscle fiber conduction velocity can be helpful in documenting sporadic occurrence of HPP. PMID:1324813

  6. Automatic versus Voluntary Motor Imitation: Effect of Visual Context and Stimulus Velocity

    PubMed Central

    Bisio, Ambra; Stucchi, Natale; Jacono, Marco; Fadiga, Luciano; Pozzo, Thierry

    2010-01-01

    Automatic imitation is the tendency to reproduce observed actions involutarily. Though this topic has been widely treated, at present little is known about the automatic imitation of the kinematic features of an observed movement. The present study was designed to understand if the kinematics of a previously seen stimulus primes the executed action, and if this effect is sensitive to the kinds of stimuli presented. We proposed a simple imitation paradigm in which a dot or a human demonstrator moved in front of the participant who was instructed either to reach the final position of the stimulus or to imitate its motion with his or her right arm. Participants' movements were automatically contaminated by stimulus velocity when it moved according to biological laws, suggesting that automatic imitation was kinematic dependent. Despite that the performance, in term of reproduced velocity, improved in a context of voluntary imitation, subjects did not replicate the observed motions exactly. These effects were not affected by the kind of stimuli used, i.e., motor responses were influenced in the same manner after dot or human observation. These findings support the existence of low-level sensory-motor matching mechanisms that work on movement planning and represent the basis for higher levels of social interaction. PMID:20976006

  7. An empirical relationship between thermal conductivity and elastic wave velocities in sandstone

    NASA Astrophysics Data System (ADS)

    Zamora, Maria; Vo-Thanh, Dung; Bienfait, Gerard; Poirier, Jean P.

    1993-08-01

    Measurements in three samples of very clean quartz sandstone in the porosity range 4-16 percent, under dry and 100 percent water-saturated conditions, show that P- and S-wave velocities are linearly correlated with thermal conductivity. The experimental results agree with the theoretical relation between seismic velocities (predicted by the Kuster and Toksoz model (1974)) and thermal conductivity (predicted by weighted geometric mean).

  8. 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

  9. 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

  10. Microfabricated multi-electrode device for detecting oligodendrocyte-regulated changes in axonal conduction velocity.

    PubMed

    Sakai, Koji; Shimba, Kenta; Kotani, Kiyoshi; Jimbo, Yasuhiko

    2015-08-01

    Myelin disorders cause cognitive dysfunction, but little is known about how abnormal myelin sheath affects neural activities at the network level. One reason for the lack is a technical difficulty in simultaneous monitoring of changes in both the axonal conduction and network activity. Then, we aimed to develop a culture device to detect myelination dependent changes in axonal conduction velocity in a neuronal network. The photolithographically fabricated device has microtunnels for guiding axons. Two microelectrodes and an oligodendrocyte (OL) culture compartment are set at each microtunnel. This configuration allows us to monitor changes in conduction velocity of axons wrapped by OLs. Neurons and OLs dissected from rat cortical tissues were cultured in the culture device. An immunocytochemical study indicated axonal growth and maturation of OL at 42 days in vitro (DIV), suggesting that neuron-OL co-culture was maintained in microtunnels. Propagating action potentials of individual axons were detected from spontaneous neural activities with a spike sorting method and their conduction velocities were examined. Conduction velocity without seeding OLs was 0.31 m/s, which was consistent with that of previous reports with unmyelinated axons. Although no apparent myelin sheath was observed in OL culture compartments, conduction delay with seeding OLs was approximately half as long as that without seeding OLs at 45 DIV. These results suggest that the culture device enables us to detect the OL-regulated changes in axonal conduction in the neuronal network. PMID:26737935

  11. 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. PMID:24585472

  12. 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.

  13. 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. PMID:25727024

  14. 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 =…

  15. Effect of magnesium on nerve conduction velocity during regular dialysis treatment

    PubMed Central

    Fleming, Laura W.; Lenman, J. A. R.; Stewart, W. K.

    1972-01-01

    Serial nerve conduction velocities in the peroneal and ulnar nerves have been measured in 10 patients on regular dialysis treatment over a three year period. Each patient alternated between phases on dialysis with magnesium-containing dialysate (1·5-1·7 m-equiv/l.) and phases on `magnesium-free' dialysate (0·2 m-equiv/l.). Plasma magnesium concentrations were high both pre- and post-dialysis during magnesium-containing dialysis, and normal to low on magnesium-free dialysis. All patients had defects in nerve conduction, mainly asymptomatic. Increases in nerve conduction velocity coincided with magnesium-free dialysis, and decreases occurred when the patients reverted to magnesium-containing dialysate. The significance of the correlation by the sign test was P<0·0005. It is concluded that extracellular magnesium levels can influence the rate of nerve conduction in vivo. PMID:4338446

  16. 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.

  17. 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...

  18. 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 using similar NCV…

  19. 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…

  20. Godunov Method for Calculating Flows of a one-Velocity Viscous Heat-Conducting Medium

    NASA Astrophysics Data System (ADS)

    Surov, V. S.

    2015-05-01

    For a hyperbolic model of a one-velocity viscous heat-conducting mixture, a modifi ed Godunov method with approximate Riemann solvers is developed. Using this method, we studied wave processes in frothing and bubble media. It is shown that the fl ow picture is signifi cantly infl uenced by heat transfer processes, which are manifested to a greater extent for bubble liquids.

  1. Optical determination of impulse conduction velocity during development of embryonic chick cervical vagus nerve bundles.

    PubMed Central

    Sakai, T; Komuro, H; Katoh, Y; Sasaki, H; Momose-Sato, Y; Kamino, K

    1991-01-01

    1. Employing an optical method for multiple-site simultaneous recording of electrical activity, we have determined the conduction velocity in cervical vagus nerve bundles isolated from 5- to 21-day-old chick embryos, and investigated its developmental changes. 2. The preparations were stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761), and action potential- (impulse-) related optical signals were elicited by brief stimuli applied to the end of the vagus nerve bundle with a suction electrode. Optical signals were recorded simultaneously from many contiguous regions using a 12 x 12-element photodiode array. 3. The optical signals spread with small delay from the site of stimulation. From the relationship between the delay and distance from the current-applying electrode, conduction velocities were estimated in each tested preparation: the conduction velocity was very small and increased monotonically from about 0.1 m s-1 at 5 days embryonic age to about 0.4 m s-1 by hatching. The increase in the conduction velocity was closely related to a developmental increase in the diameter of the vagus nerve bundle. 4. In addition, we have examined the spread of electrotonic potentials. The space constant was very small (200-450 microns) and increased as development proceeded. 5. Compound optical action signals having two distinct components were also recorded. They often appeared to be concentrated in the preparations from 8- to 12-day-old embryos. The conduction velocity of the second component was slower than that of the first. We suggest that appearance of the second component reflects degeneration of a subset of axons resulting from 'neural cell death' during the development of the vagus nerve. Images Fig. 1 Fig. 14 (cont.) Fig. 14 PMID:1895241

  2. 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. PMID:22853889

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

    PubMed

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

    2015-10-01

    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. 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

  5. Linking motor-related brain potentials and velocity profiles in multi-joint arm reaching movements.

    PubMed

    Amengual, Julià L; Marco-Pallarés, Josep; Grau, Carles; Münte, Thomas F; Rodríguez-Fornells, Antoni

    2014-01-01

    The study of the movement related brain potentials (MRPBs) needs accurate technical approaches to disentangle the specific patterns of bran activity during the preparation and execution of movements. During the last forty years, synchronizing the electromyographic activation (EMG) of the muscle with electrophysiological recordings (EEG) has been commonly ussed for these purposes. However, new clinical approaches in the study of motor diseases and rehabilitation suggest the demand of new paradigms that might go further into the study of the brain activity associated with the kinematics of movements. As a response to this call, we have used a 3-D hand-tracking system with the aim to record continuously the position of an ultrasonic sender attached to the hand during the performance of multi-joint self-paced movements. We synchronized time-series of position and velocity of the sender with the EEG recordings, obtaining specific patterns of brain activity as a function of the fluctuations of the kinematics during natural movement performance. Additionally, the distribution of the brain activity during the preparation and execution phases of movements was similar that reported previously using the EMG, suggesting the validity of our technique. We claim that this paradigm could be usable in patients because of its simplicity and the potential knowledge that can be extracted from clinical protocols. PMID:24808853

  6. Potassium currents and conductance. Comparison between motor and sensory myelinated fibers.

    PubMed Central

    Palti, Y; Moran, N; Stämpfli, R

    1980-01-01

    The potassium conductance system of sensory and motor fibers from the frog Rana esculenta were studied and compared by means of the voltage clamp. The potassium ion accumulation was first estimated from the currents and reversal potentials within the framework of both a three-compartment model and diffusion-in-an-unstirred-layer model. The potassium conductance parameters were then computed using the measured currents and corrected ionic driving forces. It was found that the potassium accumulation is faster and more pronounced in sensory fibers, the voltage dependency of the potassium conductance is steeper in sensory fibers, the maximal potassium conductance, corrected for accumulation, is approximately 1.1 S/cm2 in sensory and 0.55 S/cm2 in motor fibers, and that the conductance time constants, tau n, are smaller in sensory than in motor fibers. These differences, which increase progressively with depolarization, are not detectable for depolarization of 50 mV or smaller. The interpretation of these findings in terms of different types of potassium channels as well as their implications with regard to the differences between the excitability phenomena in motor and sensory fibers are discussed. PMID:6973371

  7. 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.

  8. 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.

  9. 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…

  10. 49 CFR 242.111 - Prior safety conduct as motor vehicle operator.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Prior safety conduct as motor vehicle operator. 242.111 Section 242.111 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION QUALIFICATION AND CERTIFICATION OF CONDUCTORS Program and Eligibility Requirements §...

  11. A comparison of nerve conduction velocities and current perception thresholds as correlates of clinical severity of diabetic sensory neuropathy.

    PubMed Central

    Rendell, M S; Katims, J J; Richter, R; Rowland, F

    1989-01-01

    Nerve conduction velocities (NCVs) are the standard measurements used to confirm the presence or absence of diabetic neuropathy. NCVs were contrasted with the newer technique of measurement of alternating current perception thresholds (CPTs) in assessing the quantitative level of correlation with severity of diabetic sensory neuropathy. A very detailed, scored neurological history (symptoms) and physical examination, emphasising sensory assessment, was conducted on 71 individuals with diabetic neuropathy of varying degrees of severity. Sensory and motor NCVs and CPTs at 5, 250, and 2000 Hz of the upper and lower extremities were determined for these individuals. In addition, vibration thresholds (VTs) were measured as a third modality. Twenty eight individuals underwent repeated evaluations at 2, 6, 10 and 12 months after the initial procedures. Using the results of 169 complete evaluations, correlations were determined between physical scores (PS) and symptoms scores (SS) and NCVs. NCV correlations with the SS were weaker than with the PS. The strongest of the correlations were found between the PS and motor NCVs of the median nerve (rho = 0.29) and the tibial nerve (rho = 0.38). Normal NCVs were present in the face of very significant historical and physical abnormality. Correlations of the SS and PS with both VTs and CPTs were higher than with the NCVs. CPTs proved the more effective as predictors of both symptomatic and physical impairment. NCVs appear to lack the resolving power necessary to evaluate subtle differences in clinical state of diabetic sensory neuropathy. The supplementary use of current perception testing may improve the quantitative assessment of this condition. PMID:2738593

  12. Structure, sound velocity, and thermal conductivity of the perovskite NdGaO3

    NASA Astrophysics Data System (ADS)

    Krivchikov, A. I.; Gorodilov, B. Ya.; Kolobov, I. G.; Érenburg, A. I.; Savitskiĭ, D. I.; Ubizskiĭ, S. B.; Syvorotka, I. M.; Vasilechko, L. O.

    2000-05-01

    X-ray (300 K) and ultrasonic (77-270 K) studies and measurements of the thermal conductivity (30-300 K) are carried out on single-crystal samples of NdGaO3 in different crystallographic directions. The values of the lattice parameters of NdGaO3 are refined. The sound velocities in the principal crystallographic directions are measured, and the elastic constants and Debye temperature are calculated. The observed anisotropy of the thermal conductivity is described in the framework of a gaskinetic model and is linked to the anisotropy of the interaction parameters of the acoustical and optical phonons.

  13. Postoperative improvement in DASH score, clinical findings, and nerve conduction velocity in patients with cubital tunnel syndrome

    PubMed Central

    Ido, Yoshikazu; Uchiyama, Shigeharu; Nakamura, Koichi; Itsubo, Toshiro; Hayashi, Masanori; Hata, Yukihiko; Imaeda, Toshihiko; Kato, Hiroyuki

    2016-01-01

    We investigated a recovery pattern in subjective and objective measures among 52 patients with cubital tunnel syndrome after anterior subcutaneous transposition of the ulnar nerve. Disabilities of the Arm, Shoulder and Hand (DASH) score (primary outcome), numbness score, grip and pinch strength, Semmes-Weinstein (SW) score, static 2-point discrimination (2PD) score, and motor conduction velocity (MCV) stage were examined preoperatively and 1, 3, 6, 12, and ≥24 months postoperatively. Statistical analyses were conducted to evaluate how each variable improved after surgery. A linear mixed-effects model was used for continuous variables (DASH score, numbness, grip and pinch strength), and a proportional odds model was used for categorical variables (SW and 2PD tests and MCV stages). DASH score significantly improved by 6 months. Significant recovery in numbness and SW test scores occurred at 1 month. Grip and pinch strength, 2PD test scores, and MCV stage improved by 3 months. DASH scores and numbness recovered regardless of age, sex, or disease severity. It was still unclear if both subjective and objective measures improved beyond 1-year postoperatively. These data are helpful for predicting postoperative recovery patterns and tend to be most important for patients prior to surgery. PMID:27263860

  14. [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

  15. Thermal conduction by dark matter with velocity and momentum-dependent cross-sections

    SciTech Connect

    Vincent, Aaron C.; Scott, Pat E-mail: patscott@physics.mcgill.ca

    2014-04-01

    We use the formalism of Gould and Raffelt [1] to compute the dimensionless thermal conduction coefficients for scattering of dark matter particles with standard model nucleons via cross-sections that depend on the relative velocity or momentum exchanged between particles. Motivated by models invoked to reconcile various recent results in direct detection, we explicitly compute the conduction coefficients α and κ for cross-sections that go as v{sub rel}{sup 2}, v{sub rel}{sup 4}, v{sub rel}{sup −2}, q{sup 2}, q{sup 4} and q{sup −2}, where v{sub rel} is the relative DM-nucleus velocity and q is the momentum transferred in the collision. We find that a v{sub rel}{sup −2} dependence can significantly enhance energy transport from the inner solar core to the outer core. The same can true for any q-dependent coupling, if the dark matter mass lies within some specific range for each coupling. This effect can complement direct searches for dark matter; combining these results with state-of-the-art solar simulations should greatly increase sensitivity to certain DM models. It also seems possible that the so-called Solar Abundance Problem could be resolved by enhanced energy transport in the solar core due to such velocity- or momentum-dependent scatterings.

  16. 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.

  17. 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.

  18. 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.

  19. 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. PMID:24784219

  20. 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

  1. 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).

  2. 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.

  3. Noninvasive peroneal sensory and motor nerve conduction recordings in the rabbit distal hindlimb: feasibility, variability and neuropathy measure.

    PubMed

    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

  4. IDENTIFYING HYDRAULICALLY CONDUCTIVE FRACTURES WITH A SLOW-VELOCITY BOREHOLE FLOWMETER.

    USGS Publications Warehouse

    Hess, Alfred E.

    1986-01-01

    The U. S. Geological Survey used a recently developed heat-pulse flowmeter to measure very slow borehole axial water velocities in granitic rock at a site near Lac du Bonnet, Manitoba, Canada. The flowmeter was used with other geophysical measurements to locate and identify hydraulically conducting fractures contributing to the very slow vertical water flow in the two boreholes selected for study. The heat-pulse flowmeter has a flow-measuring range in water of 0. 06-6m/min, and can resolve velocity differences as slow as 0. 01 m/min. This is an order of magnitude slower than the stall speed of spinner flowmeters. The flowmeter is 1. 16 m long and 44 mm in diameter. It was calibrated in columns of 76 and 152 mm diameter, to correspond to the boreholes studied. The heat-pulse flowmeter system is evaluated, and problems peculiar to the measurement of very slow axial water velocities in boreholes are discussed.

  5. 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.

  6. Evaluation of Central and Peripheral Fatigue in the Quadriceps Using Fractal Dimension and Conduction Velocity in Young Females

    PubMed Central

    Beretta-Piccoli, Matteo; D’Antona, Giuseppe; Barbero, Marco; Fisher, Beth; Dieli-Conwright, Christina M.; Clijsen, Ron; Cescon, Corrado

    2015-01-01

    Purpose Over the past decade, linear and non-linear surface electromyography descriptors for central and peripheral components of fatigue have been developed. In the current study, we tested fractal dimension (FD) and conduction velocity (CV) as myoelectric descriptors of central and peripheral fatigue, respectively. To this aim, we analyzed FD and CV slopes during sustained fatiguing contractions of the quadriceps femoris in healthy humans. Methods A total of 29 recreationally active women (mean age±standard deviation: 24±4 years) and two female elite athletes (one power athlete, age 24 and one endurance athlete, age 30 years) performed two knee extensions: (1) at 20% maximal voluntary contraction (MVC) for 30 s, and (2) at 60% MVC held until exhaustion. Surface EMG signals were detected from the vastus lateralis and vastus medialis using bidimensional arrays. Results Central and peripheral fatigue were described as decreases in FD and CV, respectively. A positive correlation between FD and CV (R=0.51, p<0.01) was found during the sustained 60% MVC, probably as a result of simultaneous motor unit synchronization and a decrease in muscle fiber CV during the fatiguing task. Conclusions Central and peripheral fatigue can be described as changes in FD and CV, at least in young, healthy women. The significant correlation between FD and CV observed at 60% MVC suggests that a mutual interaction between central and peripheral fatigue can arise during submaximal isometric contractions. PMID:25880369

  7. 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

  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. PMID:16688721

  9. Effects of colistin on the sensory nerve conduction velocity and F-wave in mice.

    PubMed

    Dai, Chongshan; Tang, Shusheng; Li, Jichang; Wang, Jiping; Xiao, Xilong

    2014-12-01

    The aim of this study was to examine the changes of sensory nerve conduction velocity (SNCV) and F-wave for colistin-induced peripheral neurotoxicity using a mouse model. Mice were administered with colistin 5, 7.5 and 15 mg/kg/day via a 3-min. intravenous infusion. The sensory nerve conduction velocity (SNCV) and F-wave were measured using the bipolar recording electrodes. The SNCV and F-wave latency changed in a dose- and time-dependent manner. The significant increase of F-wave latency and significant decrease of SNCV appeared on day 3 (p < 0.05 and 0.01, respectively) in the 15 mg/kg/day group, and they were markedly changed on day 7 in the 7.5 mg/kg/day (p < 0.01 and 0.05, respectively) and 15 mg/kg/day groups (both p < 0.01). In addition, F-wave latency also significantly increased on day 7 in the 5 mg/kg/day group (p < 0.05) without any clinical signs. These results indicate that SNCV and F-wave latency were more sensitive in colistin-induced neurotoxicity in mice, which highlights the early monitoring tool of polymyxins neurotoxicity in the clinic. PMID:24861773

  10. 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

  11. 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.

  12. 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?

  13. 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. PMID:23809191

  14. Fluid Distribution in Synthetic Wet Halite Rocks : Inference from Measured Elastic Wave Velocity and Electrical Conductivity

    NASA Astrophysics Data System (ADS)

    Watanabe, T.; Kitano, M.

    2011-12-01

    Intercrystalline fluid can significantly affect rheological and transport properties of rocks. Its influences are strongly dependent on its distribution. The dihedral angle between solid and liquid phases has been widely accepted as a key parameter that controls solid-liquid textures. The liquid phase is not expected to be interconnected if the dihedral angle is larger than 60 degree. However, observations contradictory to dihedral angle values have been reported. Watanabe (2010) suggested the coexistence of grain boundary fluid with a positive dihedral angle. For good understanding of fluid distribution, it is thus critical to study the nature of grain boundary fluid. We have developed a high pressure and temperature apparatus for study of intercrystalline fluid distribution. It was specially designed for measurements of elastic wave velocities and electrical conductivity. The apparatus mainly consists of a conventional cold-seal vessel with an external heater. The pressure medium is silicon oil of the viscosity of 0.1 Pa s. The pressure and temperature can be controlled from 0 to 200 MPa and from 20 to 200 C, respectively. Dimensions of a sample are 9 mm in diameter, and 15 mm in length. Halite-water system is used as an analog for crustal rocks. The dihedral angle has been studied systematically at various pressure and temperature conditions [Lewis and Holness, 1996]. The dihedral angle is larger than 60 degree at lower pressure and temperature. It decreases to be smaller than 60 degree with increasing pressure and temperature. A sample is prepared by cold-pressing and annealing of wet NaCl powder. Optical examination has shown that synthesized samples are microstructurally homogeneous. Grains are polygonal and equidimensional with a mean diameter of 100 micrometer. Grain boundaries vary from straight to bowed and 120 degree triple junctions are common. Gas and fluid bearing inclusions are visible on the grain boundaries. There are spherical inclusions or

  15. MICROBIAL TRANSPORT THROUGH POROUS MEDIA; THE EFFECTS OF HYDRAULIC CONDUCTIVITY AND INJECTION VELOCITY. (R825513C019)

    EPA Science Inventory

    The effects of hydraulic conductivity and injection velocity on microbial transport through porous media were investigated. Glass chromatography columns were packed separately with clean quartz sand of two diameters (0.368mm or 0.24O mm) and two hydraulic conductivities (1.37&...

  16. 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…

  17. Severe COPD Alters Muscle Fiber Conduction Velocity During Knee Extensors Fatiguing Contraction.

    PubMed

    Boccia, Gennaro; Coratella, Giuseppe; Dardanello, Davide; Rinaldo, Nicoletta; Lanza, Massimo; Schena, Federico; Rainoldi, Alberto

    2016-10-01

    The aim of this study was to assess the changes in muscle fiber conduction velocity (CV), as a sign of fatigue during knee extensor contraction in patients with chronic obstructive pulmonary disease (COPD) as compared with healthy controls. Eleven male patients (5 with severe and 6 with moderate COPD; age 67 ± 5 years) and 11 age-matched healthy male controls (age 65 ± 4 years) volunteered for the study. CV was obtained by multichannel surface electromyography (EMG) from the vastus lateralis (VL) and medialis (VM) of the quadriceps muscle during isometric, 30-second duration knee extension at 70% of maximal voluntary contraction. The decline in CV in both the VL and VM was steeper in the severe COPD patients than in healthy controls (for VL: severe COPD vs. controls -0.45 ± 0.07%/s; p < 0.001, and for VM: severe COPD vs. controls -0.54 ± 0.09%/s, p < 0.001). No difference in CV decline was found between the moderate COPD patients and the healthy controls. These findings suggest that severe COPD may impair muscle functions, leading to greater muscular fatigue, as expressed by CV changes. The results may be due to a greater involvement of anaerobic metabolism and a shift towards fatigable type II fibers in the muscle composition of the severe COPD patients. PMID:27007486

  18. Exercise and DHA prevent the negative effects of hypoxia on EEG and nerve conduction velocity.

    PubMed

    Erken, Haydar Ali; Erken, Gülten; Colak, Rıdvan; Genç, Osman

    2013-12-01

    It is known that hypoxia has a negative effect on nervous system functions, but exercise and DHA (docosahexaenoic acid) have positive effect. In this study, it was investigated whether exercise and/or DHA can prevent the effects of hypoxia on EEG and nerve conduction velocity (NCV). 35 adult Wistar albino male rats were divided into five groups (n=7): control (C), hypoxia (H), hypoxia and exercise (HE), hypoxia and DHA (HD), and hypoxia and exercise and DHA (HED) groups. During the 28-day hypoxia exposure, the HE and HED groups of rats were exercised (0% incline, 30 m/min speed, 20 min/day, 5 days a week). In addition, DHA (36 mg/kg/day) was given by oral gavage to rats in the HD and HED groups. While EEG records were taken before and after the experimental period, NCV records were taken after the experimental period from anesthetized rats. Data were analyzed by paired t-test, one-way ANOVA, and post hoc Tukey test. In this study, it was shown that exposure to hypoxia decreased theta activity and NCV, but exercise and DHA reduced the delta activity, while theta, alpha, beta activities, and NCV were increased. These results have shown that the effects of hypoxia exposure on EEG and NCV can be prevented by exercise and/or DHA. PMID:24377343

  19. Brain Activity During a Motor Learning Task: An fMRI and Skin Conductance Study

    PubMed Central

    MacIntosh, Bradley J.; Mraz, Richard; McIlroy, William E.; Graham, Simon J.

    2016-01-01

    Measuring electrodermal activity (EDA) during fMRI is an effective means of studying the influence of task-related arousal, inferred from autonomic nervous system activity, on brain activation patterns. The goals of this study were: (1) to measure reliable EDA from healthy individuals during fMRI involving an effortful unilateral motor task, (2) to explore how EDA recordings can be used to augment fMRI data analysis. In addition to conventional hemodynamic modeling, skin conductance time series data were used as model waveforms to generate activation images from fMRI data. Activations from the EDA model produced significantly different brain regions from those obtained with a standard hemodynamic model, primarily in the insula and cingulate cortices. Onsets of the EDA changes were synchronous with the hemodynamic model, but EDA data showed additional transient features, such as a decrease in amplitude with time, and helped to provide behavioral evidence suggesting task difficulty decreased with movement repetition. Univariate statistics also confirmed that several brain regions showed early versus late session effects. Partial least squares (PLS) multivariate analysis of EDA and fMRI data provided complimentary, additional insight on how the motor network varied over the course of a single fMRI session. Brain regions identified in this manner included the insula, cingulate gyrus, pre- and postcentral gyri, putamen and parietal cortices. These results suggest that recording EDA during motor fMRI experiments provides complementary information that can be used to improve the fMRI analysis, particularly when behavioral or task effects are difficult to model a priori. PMID:17318835

  20. 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.

  1. 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

  2. Unchanged muscle fiber conduction velocity relates to mild acidosis during exhaustive bicycling.

    PubMed

    Schmitz, J P J; van Dijk, J P; Hilbers, P A J; Nicolay, K; Jeneson, J A L; Stegeman, D F

    2012-05-01

    Muscle fiber conduction velocity (MFCV) has often been shown to decrease during standardized fatiguing isometric contractions. However, several studies have indicated that the MFCV may remain constant during fatiguing dynamic exercise. It was investigated if these observations can be related to the absence of a large decrease in pH and if MFCV can be considered as a good indicator of acidosis, also during dynamic bicycle exercise. High-density surface electromyography (HDsEMG) was combined with read-outs of muscle energetics recorded by in vivo (31)P magnetic resonance spectroscopy (MRS). Measurements were performed during serial exhausting bouts of bicycle exercise at three different workloads. The HDsEMG recordings revealed a small and incoherent variation of MFCV during all high-intensity exercise bouts. (31)P MRS spectra revealed a moderate decrease in pH at the end of exercise (~0.3 units down to 6.8) and a rapid ancillary drop to pH 6.5 during recovery 30 s post-exercise. This additional degree of acidification caused a significant decrease in MFCV during cycling immediately after the rest period. From the data a significant correlation between MFCV and [H(+)] ([H(+)] = 10(-pH)) was calculated (p < 0.001, Pearson's R = -0.87). Our results confirmed the previous observations of MFCV remaining constant during fatiguing dynamic exercise. A constant MFCV is in line with a low degree of acidification, considering the presence of a correlation between pH and MFCV after further increasing acidification. PMID:21861110

  3. Conduction velocity of the uterine contraction in serial magnetomyogram (MMG) data: event based simulation and validation.

    PubMed

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

    2011-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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 switches connected to a digital stopwatch. The timer assembly was then used to observe the variation in the terminal velocity of the falling magnet with respect to the thickness of the copper pipes.

  5. 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

  6. 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.

  7. Influence of Pore-Fluid Pressure on Elastic Wave Velocity and Electrical Conductivity in Water-Saturated Rocks

    NASA Astrophysics Data System (ADS)

    Higuchi, A.; Watanabe, T.

    2013-12-01

    Pore-fluid pressure in seismogenic zones can play a key role in the occurrence of earthquakes (e.g., Sibson, 2009). Its evaluation via geophysical observations can lead to a good understanding of seismic activities. The evaluation requires a thorough understanding of the influence of the pore-fluid pressure on geophysical observables like seismic velocity and electrical conductivity. We have studied the influence of pore-fluid pressure on elastic wave velocity and electrical conductivity in water-saturated rocks. Fine grained (100-500μm) biotite granite (Aji, Kagawa pref., Japan) was used as rock samples. The density is 2.658-2.668 g/cm3, and the porosity 0.68-0.87%. The sample is composed of 52.8% plagioclase, 36.0% Quartz, 3.0% K-feldspar, 8.2% biotite. SEM images show that a lot of grain boundaries are open. Few intracrystalline cracks were observed. Following the method proposed by David and Zimmerman (2012), the distribution function of crack aspect ratio was evaluated from the pressure dependence of compressional and shear wave velocities in a dry sample. Cylindrical sample has dimensions of 25 mm in diameter and 30 mm in length, and saturated with 0.01 mol/l KCl aqueous solution. Compressional and shear wave velocities were measured with the pulse transmission technique (PZT transducers, f=2 MHz), and electrical conductivity the two-electrode method (Ag-AgCl electrodes, f=1 Hz-100 kHz). Simultaneous measurements of velocities and conductivity were made using a 200 MPa hydrostatic pressure vessel, in which confining and pore-fluid pressures can be separately controlled. The pore-fluid is electrically insulated from the metal work of the pressure vessel by using a newly designed plastic device (Watanabe and Higuchi, 2013). The confining pressure was progressively increased up to 25 MPa, while the pore-fluid pressure was kept at 0.1 MPa. It took five days or longer for the electrical conductivity to become stationary after increasing the confining pressure

  8. 49 CFR 240.111 - Individual's duty to furnish data on prior safety conduct as motor vehicle operator.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Individual's duty to furnish data on prior safety conduct as motor vehicle operator. 240.111 Section 240.111 Transportation Other Regulations Relating to... CERTIFICATION OF LOCOMOTIVE ENGINEERS Component Elements of the Certification Process § 240.111...

  9. 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…

  10. Magnetic motor evoked potentials in ponies.

    PubMed

    Mayhew, I G; Washbourne, J R

    1996-01-01

    Magnetic stimulation of motor pathways was used to effect motor unit action potential recordings from forelimb and hindlimb muscles in unanesthetized ponies. Motor pathway conduction velocities to the forelimb and hindlimb were determined to be 53.8 +/- 9.6 m/s-1 and 63.4 +/- 8.3 m/s-1, respectively. This noninvasive technique will enable more precise evaluation of motor deficits in clinical patients than is possible with the neurological examination. PMID:8884720

  11. Motor function and perception in children with neuropsychiatric and conduct problems: results from a population based twin study

    PubMed Central

    2014-01-01

    Background Children with early symptomatic psychiatric disorders such as Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) have been found to have high rates of motor and/or perception difficulties. However, there have been few large-scale studies reporting on the association between Conduct Disorder (CD) and motor/perception functions. The aim of the present study was to investigate how motor function and perception relate to measures of ADHD, ASD, and CD. Methods Parents of 16,994 Swedish twins (ages nine and twelve years) were interviewed using the Autism-Tics, ADHD and other Comorbidities inventory (A-TAC), which has been validated as a screening instrument for early onset child psychiatric disorders and symptoms. Associations between categorical variables of scoring above previously validated cut-off values for diagnosing ADHD, ASD, and CD on the one hand and motor and/or perception problems on the other hand were analysed using cross-tabulations, and the Fisher exact test. Associations between the continuous scores for ADHD, ASD, CD, and the subdomains Concentration/Attention, Impulsiveness/Activity, Flexibility, Social Interaction and Language, and the categorical factors age and gender, on the one hand, and the dependent dichotomic variables Motor control and Perception problems, on the other hand, were analysed using binary logistic regression in general estimated equation models. Results Male gender was associated with increased risk of Motor control and/or Perception problems. Children scoring above the cut-off for ADHD, ASD, and/or CD, but not those who were ‘CD positive’ but ‘ADHD/ASD negative’, had more Motor control and/or Perception problems, compared with children who were screen-negative for all three diagnoses. In the multivariable model, CD and Impulsiveness/Activity had no positive associations with Motor control and/or Perception problems. Conclusions CD symptoms or problems with Impulsiveness

  12. Receptive field size, chemical and thermal responses, and fiber conduction velocity of rat chorda tympani geniculate ganglion neurons.

    PubMed

    Yokota, Yusuke; Bradley, Robert M

    2016-06-01

    Afferent chorda tympani (CT) fibers innervating taste and somatosensory receptors in fungiform papillae have neuron cell bodies in the geniculate ganglion (GG). The GG/CT fibers branch in the tongue to innervate taste buds in several fungiform papillae. To investigate receptive field characteristics of GG/CT neurons, we recorded extracellular responses from GG cells to application of chemical and thermal stimuli. Receptive field size was mapped by electrical stimulation of individual fungiform papillae. Response latency to electrical stimulation was used to determine fiber conduction velocity. Responses of GG neurons to lingual application of stimuli representing four taste qualities, and water at 4°C, were used to classify neuron response properties. Neurons classified as SALT, responding only to NaCl and NH4Cl, had a mean receptive field size of six papillae. Neurons classified as OTHER responded to salts and other chemical stimuli and had smaller mean receptive fields of four papillae. Neurons that responded to salts and cold stimuli, classified as SALT/THERMAL, and neurons responding to salts, other chemical stimuli and cold, classified as OTHER/THERMAL, had mean receptive field sizes of six and five papillae, respectively. Neurons responding only to cold stimuli, categorized as THERMAL, had receptive fields of one to two papillae located at the tongue tip. Based on conduction velocity most of the neurons were classified as C fibers. Neurons with large receptive fields had higher conduction velocities than neurons with small receptive fields. These results demonstrate that GG neurons can be distinguished by receptive field size, response properties and afferent fiber conduction velocity derived from convergent input of multiple taste organs. PMID:27030734

  13. The Effect of the Silicone Ring Tourniquet and Standard Pneumatic Tourniquet on the Motor Nerve Conduction, Pain and Grip Strength in Healthy Volunteers

    PubMed Central

    Drosos, Georgios I.; Kiziridis, Georgios; Aggelopoulou, Cristina; Galiatsatos, Dimitrios; Anastassopoulos, George; Ververidis, Athanasios; Kazakos, Konstantinos

    2016-01-01

    Background: The pneumatic tourniquet (PT) is routinely used in upper and lower limb operations by most orthopaedic surgeons. The silicone ring tourniquet (SRT) was introduced in clinical practice over the last decade. Clinical as well as comparative studies have been published in volunteers concerning its safety and efficacy. The aim of this study was to investigate the postoperative effect of the silicone ring tourniquet (SRT), primarily on the motor nerve conduction, and secondarily on the pain and grip strength, in comparison to the effect of the pneumatic tourniquet (PT) in healthy volunteers. Methods: Both tourniquets were applied in the forearm of the dominant arm in 20 healthy volunteers and were kept on for 10 minutes. Pain was measured using the visual analogue scale and grip strength was measured with a hand dynamometer. We evaluated the following parameters of median nerve conduction: motor conduction velocity (MCV), latency (LAT) and amplitude (AMP). Results: Pain score at the time of tourniquet application was higher in SRT group but the alteration in pain scores in PT group was higher, with statistical significance (P<0.05). The grip strength was reduced by the application of both tourniquets; however there was a significantly higher reduction in the SRT group (P<0.05). The conduction impairment of the median nerve was worse in the PT group than in the SRT one, according to the changes in MCV (P<0.05). Conclusion: Median nerve conduction was affected more after PT application as compared to the SRT. Nevertheless, the reduction of grip strength was higher after the SRT application. PMID:26894213

  14. The physiological effect of anti-GM1 antibodies on saltatory conduction and transmembrane currents in single motor axons.

    PubMed

    Hirota, N; Kaji, R; Bostock, H; Shindo, K; Kawasaki, T; Mizutani, K; Oka, N; Kohara, N; Saida, T; Kimura, J

    1997-12-01

    Anti-ganglioside (anti-GM1) antibodies have been implicated in the pathogenesis of Guillain-Barré syndrome, multifocal motor neuropathy and motor neuron diseases. It has been held that they may interfere with saltatory conduction by blocking sodium channels. We tested this hypothesis by analysing action potentials from 140 single nerve fibres in 22 rat ventral roots using external longitudinal current measurement. High-titre anti-GM1 sera from Guillain-Barré syndrome or multifocal motor neuropathy patients, or anti-GM1 rabbit sera were applied to the rat ventral root, where saltatory conduction in single motor fibres was serially observed for 4-12 h (mean 8.2 h). For control experiments, we also tested anti-galactocerebroside (anti-GalC) sera, which causes acute demyelinative conduction block, and tetrodotoxin (TTX), a sodium channel blocker. Conduction block was found in 82% of the fibres treated with anti-GalC sera and 100% treated with TTX, but only in 2% (one out of 44) treated with the patients' sera and 5% (two out of 38) treated with rabbit anti-GM1 sera. All the nodes blocked by anti-GM1 sera revealed intense passive outward membrane current, in the internode just beyond the last active node. This pattern of current flow was similar to that in fibres blocked by demyelination with anti-GalC sera, and quite different from that seen in fibres blocked by reducing sodium currents with TTX. Our findings suggest that anti-GM1 sera neither mediate conduction block nor block sodium channels on their own. We conclude that physiological action of the antibody alone is insufficient to explain clinically observed conduction block in human diseases. PMID:9448571

  15. Motor nerve inexcitability in Guillain-Barré syndrome. The spectrum of distal conduction block and axonal degeneration.

    PubMed

    Triggs, W J; Cros, D; Gominak, S C; Zuniga, G; Beric, A; Shahani, B T; Ropper, A H; Roongta, S M

    1992-10-01

    We studied 34 patients with the Guillain-Barré syndrome (GBS) to clarify the clinical significance of inexcitable motor nerves and of low amplitude compound muscle action potentials (CMAPs). The patients were subdivided into two groups. Group 1 included eight patients who had electrically inexcitable motor nerves within 2 wks of the first symptom. (Two patients without extensive conduction studies had only one inexcitable motor nerve.) The outcome in this group at 1 yr varied from complete recovery (five patients) to severe motor sequelae (three patients). Group 2 included 26 patients who had two electrophysiological assessments, and in whom the serial changes in CMAP amplitudes were analysed and correlated to outcome. Fourteen of these 26 sets of serial studies were performed within 1 mth. Twelve of 26 patients in Group 2 showed decrease in the amplitude of CMAPs between serial studies; only six of these had a good outcome at 1 yr. Nine of 26 patients showed increase in CMAP amplitude between serial studies, of these eight had a good clinical outcome. Low-amplitude CMAPs or inexcitable motor nerves in the initial stages of GBS are due to distal pathology of the motor axons, either distal conduction block or axonal degeneration. The nature of these changes cannot be predicted by the results of the initial electrophysiological evaluation, including the presence or absence of active denervation. However, improvement of CMAP amplitude on sequential studies suggests a good outcome at 1 yr. We believe that, in the absence of a biological marker for GBS, individualization of an 'axonal variant' of the syndrome is not warranted at the present time. PMID:1422789

  16. 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

  17. Focal axonal swellings and associated ultrastructural changes attenuate conduction velocity in central nervous system axons: a computer modeling study.

    PubMed

    Kolaric, Katarina V; Thomson, Gemma; Edgar, Julia M; Brown, Angus M

    2013-08-01

    The constancy of action potential conduction in the central nervous system (CNS) relies on uniform axon diameter coupled with fidelity of the overlying myelin providing high-resistance, low capacitance insulation. Whereas the effects of demyelination on conduction have been extensively studied/modeled, equivalent studies on the repercussions for conduction of axon swelling, a common early pathological feature of (potentially reversible) axonal injury, are lacking. The recent description of experimentally acquired morphological and electrical properties of small CNS axons and oligodendrocytes prompted us to incorporate these data into a computer model, with the aim of simulating the effects of focal axon swelling on action potential conduction. A single swelling on an otherwise intact axon, as occurs in optic nerve axons of Cnp1 null mice caused a small decrease in conduction velocity. The presence of single swellings on multiple contiguous internodal regions (INR), as likely occurs in advanced disease, caused qualitatively similar results, except the dimensions of the swellings required to produce equivalent attenuation of conduction were significantly decreased. Our simulations of the consequences of metabolic insult to axons, namely, the appearance of multiple swollen regions, accompanied by perturbation of overlying myelin and increased axolemmal permeability, contained within a single INR, revealed that conduction block occurred when the dimensions of the simulated swellings were within the limits of those measured experimentally, suggesting that multiple swellings on a single axon could contribute to axonal dysfunction, and that increased axolemmal permeability is the decisive factor that promotes conduction block. PMID:24303138

  18. Focal axonal swellings and associated ultrastructural changes attenuate conduction velocity in central nervous system axons: a computer modeling study

    PubMed Central

    Kolaric, Katarina V; Thomson, Gemma; Edgar, Julia M; Brown, Angus M

    2013-01-01

    The constancy of action potential conduction in the central nervous system (CNS) relies on uniform axon diameter coupled with fidelity of the overlying myelin providing high-resistance, low capacitance insulation. Whereas the effects of demyelination on conduction have been extensively studied/modeled, equivalent studies on the repercussions for conduction of axon swelling, a common early pathological feature of (potentially reversible) axonal injury, are lacking. The recent description of experimentally acquired morphological and electrical properties of small CNS axons and oligodendrocytes prompted us to incorporate these data into a computer model, with the aim of simulating the effects of focal axon swelling on action potential conduction. A single swelling on an otherwise intact axon, as occurs in optic nerve axons of Cnp1 null mice caused a small decrease in conduction velocity. The presence of single swellings on multiple contiguous internodal regions (INR), as likely occurs in advanced disease, caused qualitatively similar results, except the dimensions of the swellings required to produce equivalent attenuation of conduction were significantly decreased. Our simulations of the consequences of metabolic insult to axons, namely, the appearance of multiple swollen regions, accompanied by perturbation of overlying myelin and increased axolemmal permeability, contained within a single INR, revealed that conduction block occurred when the dimensions of the simulated swellings were within the limits of those measured experimentally, suggesting that multiple swellings on a single axon could contribute to axonal dysfunction, and that increased axolemmal permeability is the decisive factor that promotes conduction block. PMID:24303138

  19. Demographics, Velocity Distributions, and Impact Type as Predictors of AIS 4+ Head Injuries in Motor Vehicle Crashes

    PubMed Central

    Yoganandan, Narayan; Fitzharris, Michael; Pintar, Frank A.; Stemper, Brian D.; Rinaldi, James; Maiman, Dennis J.; Fildes, Brian N.

    2011-01-01

    The objective of the study was to determine differences between the United States-based NASS and CIREN and Australia-based ANCIS databases in occupant-, crash-, and vehicle-related parameters for AIS 4+ head injuries in motor vehicle crashes. Logistic regression analysis was performed to examine roles of the change in velocity (DV), crash type (frontal, far-side, nearside, rear impact), seatbelt use, and occupant position, gender, age, stature, and body mass in cranial traumas. Belted and unbelted non-ejected occupant (age >16 years) data from 1997–2006 were used for the NASS and CIREN datasets, and 2000–2010 for ANCIS. Vehicle model year, and occupant position and demographics including body mass index (BMI) data were obtained. Injuries were coded using AIS 1990–1998 update. Similarities were apparent across all databases: mean demographics were close to the mid-size anthropometry, mean BMI was in the normal to overweight range, and representations of extreme variations were uncommon. Side impacts contributed to over one-half of the ensemble, implying susceptibility to head trauma in this mode. Odds of sustaining head injury increased by 4% per unit increase in DV (OR: 1.04, 95% CI: 1.03–1.04, p<0.001; adjusted for other variables); one-half for belted compared to unbelted occupants (OR: 0.48, 95% CI: 0.37–0.61, p<0.001); nearside, then far-side had significantly higher odds than frontal, and no difference by gender or position (front-left, front-right). Similar crash- and occupant-related outcomes from the two continents indicate a worldwide need to revise the translation acceleration-based head injury criterion to include the angular component in an appropriate format for improved injury assessment and mitigation. PMID:22105402

  20. Demographics, Velocity Distributions, and Impact Type as Predictors of AIS 4+ Head Injuries in Motor Vehicle Crashes.

    PubMed

    Yoganandan, Narayan; Fitzharris, Michael; Pintar, Frank A; Stemper, Brian D; Rinaldi, James; Maiman, Dennis J; Fildes, Brian N

    2011-01-01

    The objective of the study was to determine differences between the United States-based NASS and CIREN and Australia-based ANCIS databases in occupant-, crash-, and vehicle-related parameters for AIS 4+ head injuries in motor vehicle crashes. Logistic regression analysis was performed to examine roles of the change in velocity (DV), crash type (frontal, far-side, nearside, rear impact), seatbelt use, and occupant position, gender, age, stature, and body mass in cranial traumas. Belted and unbelted non-ejected occupant (age >16 years) data from 1997-2006 were used for the NASS and CIREN datasets, and 2000-2010 for ANCIS. Vehicle model year, and occupant position and demographics including body mass index (BMI) data were obtained. Injuries were coded using AIS 1990-1998 update. Similarities were apparent across all databases: mean demographics were close to the mid-size anthropometry, mean BMI was in the normal to overweight range, and representations of extreme variations were uncommon. Side impacts contributed to over one-half of the ensemble, implying susceptibility to head trauma in this mode. Odds of sustaining head injury increased by 4% per unit increase in DV (OR: 1.04, 95% CI: 1.03-1.04, p<0.001; adjusted for other variables); one-half for belted compared to unbelted occupants (OR: 0.48, 95% CI: 0.37-0.61, p<0.001); nearside, then far-side had significantly higher odds than frontal, and no difference by gender or position (front-left, front-right). Similar crash- and occupant-related outcomes from the two continents indicate a worldwide need to revise the translation acceleration-based head injury criterion to include the angular component in an appropriate format for improved injury assessment and mitigation. PMID:22105402

  1. Reduced endplate currents underlie motor unit dysfunction in canine motor neuron disease.

    PubMed

    Rich, Mark M; Waldeck, Robert F; Cork, Linda C; Balice-Gordon, Rita J; Fyffe, Robert E W; Wang, Xueyong; Cope, Timothy C; Pinter, Martin J

    2002-12-01

    Hereditary canine spinal muscular atrophy (HCSMA) is an autosomal dominant degenerative disorder of motor neurons. In homozygous animals, motor units produce decreased force output and fail during repetitive activity. Previous studies suggest that decreased efficacy of neuromuscular transmission underlies these abnormalities. To examine this, we recorded muscle fiber endplate currents (EPCs) and found reduced amplitudes and increased failures during nerve stimulation in homozygotes compared with wild-type controls. Comparison of EPC amplitudes with muscle fiber current thresholds indicate that many EPCs from homozygotes fall below threshold for activating muscle fibers but can be raised above threshold following potentiation. To determine whether axonal abnormalities might play a role in causing motor unit dysfunction, we examined the postnatal maturation of axonal conduction velocity in relation to the appearance of tetanic failure. We also examined intracellularly labeled motor neurons for evidence of axonal neurofilament accumulations, which are found in many instances of motor neuron disease including HCSMA. Despite the appearance of tetanic failure between 90 and 120 days, average motor axon conduction velocity increased with age in homozygotes and achieved adult levels. Normal correlations between motor neuron properties (including conduction velocity) and motor unit properties were also observed. Labeled proximal motor axons of several motor neurons that supplied failing motor units exhibited little or no evidence of axonal swellings. We conclude that decreased release of transmitter from motor terminals underlies motor unit dysfunction in HCSMA and that the mechanisms determining the maturation of axonal conduction velocity and the pattern of correlation between motor neuron and motor unit properties do not contribute to the appearance or evolution of motor unit dysfunction. PMID:12466447

  2. Bral1: its role in diffusion barrier formation and conduction velocity in the CNS.

    PubMed

    Bekku, Yoko; Vargová, Lýdia; Goto, Yoshinobu; Vorísek, Ivan; Dmytrenko, Lesia; Narasaki, Masahiro; Ohtsuka, Aiji; Fässler, Reinhard; Ninomiya, Yoshifumi; Syková, Eva; Oohashi, Toshitaka

    2010-02-24

    At the nodes of Ranvier, excitable axon membranes are exposed directly to the extracellular fluid. Cations are accumulated and depleted in the local extracellular nodal region during action potential propagation, but the impact of the extranodal micromilieu on signal propagation still remains unclear. Brain-specific hyaluronan-binding link protein, Bral1, colocalizes and forms complexes with negatively charged extracellular matrix (ECM) proteins, such as versican V2 and brevican, at the nodes of Ranvier in the myelinated white matter. The link protein family, including Bral1, appears to be the linchpin of these hyaluronan-bound ECM complexes. Here we report that the hyaluronan-associated ECM no longer shows a nodal pattern and that CNS nerve conduction is markedly decreased in Bral1-deficient mice even though there were no differences between wild-type and mutant mice in the clustering or transition of ion channels at the nodes or in the tissue morphology around the nodes of Ranvier. However, changes in the extracellular space diffusion parameters, measured by the real-time iontophoretic method and diffusion-weighted magnetic resonance imaging (MRI), suggest a reduction in the diffusion hindrances in the white matter of mutant mice. These findings provide a better understanding of the mechanisms underlying the accumulation of cations due to diffusion barriers around the nodes during saltatory conduction, which further implies the importance of the Bral1-based extramilieu for neuronal conductivity. PMID:20181608

  3. Acceleration of conduction velocity linked to clustering of nodal components precedes myelination

    PubMed Central

    Freeman, Sean A.; Desmazières, Anne; Simonnet, Jean; Gatta, Marie; Pfeiffer, Friederike; Aigrot, Marie Stéphane; Rappeneau, Quentin; Guerreiro, Serge; Michel, Patrick Pierre; Yanagawa, Yuchio; Barbin, Gilles; Brophy, Peter J.; Fricker, Desdemona; Lubetzki, Catherine; Sol-Foulon, Nathalie

    2015-01-01

    High-density accumulation of voltage-gated sodium (Nav) channels at nodes of Ranvier ensures rapid saltatory conduction along myelinated axons. To gain insight into mechanisms of node assembly in the CNS, we focused on early steps of nodal protein clustering. We show in hippocampal cultures that prenodes (i.e., clusters of Nav channels colocalizing with the scaffold protein ankyrinG and nodal cell adhesion molecules) are detected before myelin deposition along axons. These clusters can be induced on purified neurons by addition of oligodendroglial-secreted factor(s), whereas ankyrinG silencing prevents their formation. The Nav isoforms Nav1.1, Nav1.2, and Nav1.6 are detected at prenodes, with Nav1.6 progressively replacing Nav1.2 over time in hippocampal neurons cultured with oligodendrocytes and astrocytes. However, the oligodendrocyte-secreted factor(s) can induce the clustering of Nav1.1 and Nav1.2 but not of Nav1.6 on purified neurons. We observed that prenodes are restricted to GABAergic neurons, whereas clustering of nodal proteins only occurs concomitantly with myelin ensheathment on pyramidal neurons, implying separate mechanisms of assembly among different neuronal subpopulations. To address the functional significance of these early clusters, we used single-axon electrophysiological recordings in vitro and showed that prenode formation is sufficient to accelerate the speed of axonal conduction before myelination. Finally, we provide evidence that prenodal clusters are also detected in vivo before myelination, further strengthening their physiological relevance. PMID:25561543

  4. Acceleration of conduction velocity linked to clustering of nodal components precedes myelination.

    PubMed

    Freeman, Sean A; Desmazières, Anne; Simonnet, Jean; Gatta, Marie; Pfeiffer, Friederike; Aigrot, Marie Stéphane; Rappeneau, Quentin; Guerreiro, Serge; Michel, Patrick Pierre; Yanagawa, Yuchio; Barbin, Gilles; Brophy, Peter J; Fricker, Desdemona; Lubetzki, Catherine; Sol-Foulon, Nathalie

    2015-01-20

    High-density accumulation of voltage-gated sodium (Nav) channels at nodes of Ranvier ensures rapid saltatory conduction along myelinated axons. To gain insight into mechanisms of node assembly in the CNS, we focused on early steps of nodal protein clustering. We show in hippocampal cultures that prenodes (i.e., clusters of Nav channels colocalizing with the scaffold protein ankyrinG and nodal cell adhesion molecules) are detected before myelin deposition along axons. These clusters can be induced on purified neurons by addition of oligodendroglial-secreted factor(s), whereas ankyrinG silencing prevents their formation. The Nav isoforms Nav1.1, Nav1.2, and Nav1.6 are detected at prenodes, with Nav1.6 progressively replacing Nav1.2 over time in hippocampal neurons cultured with oligodendrocytes and astrocytes. However, the oligodendrocyte-secreted factor(s) can induce the clustering of Nav1.1 and Nav1.2 but not of Nav1.6 on purified neurons. We observed that prenodes are restricted to GABAergic neurons, whereas clustering of nodal proteins only occurs concomitantly with myelin ensheathment on pyramidal neurons, implying separate mechanisms of assembly among different neuronal subpopulations. To address the functional significance of these early clusters, we used single-axon electrophysiological recordings in vitro and showed that prenode formation is sufficient to accelerate the speed of axonal conduction before myelination. Finally, we provide evidence that prenodal clusters are also detected in vivo before myelination, further strengthening their physiological relevance. PMID:25561543

  5. Factors controlling the variances of seismic velocity, density, thermal conductivity and heat production of cores from the KTB Pilot Hole

    NASA Astrophysics Data System (ADS)

    Huenges, Ernst

    This paper presents a statistical analysis of about 50000 petrophysical data measured on core samples from the Continental Deep Drilling Project (KTB) of the Federal Republic of Germany. The scattering of the data must be taken into consideration using empirical relationships between pairs of parameters, e.g., sound velocity, density, heat production and thermal conductivity. Such covariances of parameters were calculated and used to find the principle components by applying factor analysis. The reduction of parameters by factor analysis may help other scientists to concentrate on the essential parameters to be measured. About 50% of the variance of all data can be explained by one background variable, the so-called “lithology factor”. The variables that load a factor are either highly correlated or anticorrelated. The lithology factor combines gamma spectroscopy data, density and the mineral contents of quartz, amphibole, garnet and white mica. Seismic velocities and porosity data, however, were less well related to the lithology factor. Therefore, the KTB data indicate that correlation between seismic velocity and one of the lithology factor loading variables is unlikely. The lithology factor distinguishes 3 major “rock types”: metabasites, gneisses and an intermediate type. The variance of the petrophysical parameters within the rock types, plotted in crossplots, show the level of validity of commonly used relationships among these parameters. Measurements under ambient and simulated in-situ conditions are included to enable discussion of chemical, mineralogical and microstructural characteristics of the rocks.

  6. 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.

  7. 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.

  8. Responses in muscle afferent fibres of slow conduction velocity to contractions and ischaemia in the cat.

    PubMed Central

    Mense, S; Stahnke, M

    1983-01-01

    The aim of the study was to find out to what extent muscle receptors with slowly conducting afferent fibres (group III and IV) are activated by muscular contractions of moderate force, and what kind of muscle afferents could mediate the pain of ischaemic exercise. In chloralose-anaesthetized cats, the impulse activity of single afferent units from the triceps surae muscle was recorded from dorsal root filaments during muscular contractions with intact blood supply and after occlusion of the muscle artery. Two types of responses were observed to contractions without muscular ischaemia. One was characterized by sudden onset and a graded response amplitude to contractions of increasing force. In most cases stretching the muscle was also an effective stimulus. Units showing this response behaviour were labelled c.s.m (contraction-sensitive with mechanical mechanism of activation). The other response type had a more delayed onset and often outlasted the exercise period; because of the unknown mechanism of activation, units of this kind were labelled c.s.x. The proportion of c.s.m receptors was significantly higher amongst group III than amongst group IV units. During ischaemic contractions of comparable force the c.s.m and c.s.x receptors exhibited an unchanged or a decreased response amplitude. Under these conditions another receptor type (N, for nociceptive) was activated which did not respond to contractions with intact blood supply. Vigorous activations during ischaemic work were only observed in group IV receptors. The majority of the 131 group III and IV units tested did not respond to contractions at all. These contraction-insensitive (c.i.) endings probably comprised different receptor populations (nociceptors, thermoreceptors, low-threshold mechanoreceptors). It is concluded that the various central nervous effects of muscular exercise without ischaemia which are known to be due to raised activity in thin muscle afferents (e.g. cardiopulmonary adjustments

  9. Discovery of gradient pattern in dominant frequency maps during fibrillation: implication of rotor drift and epicardial conduction velocity changes.

    PubMed

    Joel, Suresh E; Hsia, Peng-Wie

    2005-10-01

    Dominant frequency (DF) maps for mapping epicardial activations of ventricular fibrillation (VF) have been studied mainly using fast Fourier transform (FFT). Small and discrete DF domains exhibited in these DF maps have undermined the hypothesis of mother rotor for VF maintenance. We applied continuous Fourier transform (CFT) to generate high-precision DF maps and studied characteristics of these high-precision DF maps. Optical epicardial activations were recorded in isolated rabbit hearts (n=10). Continuous Fourier transform of 1-second segments was performed in VF (n=188) and ventricular tachycardia (n=189) at 0.1 Hz precisions. Banded gradient patterns of gradual change in DF values were observed in 136 of 188 VF segments, but not in ventricular tachycardia. These gradients were not observed when FFT was used. Gradients were observed along the conduction path of reentrant-like waves with decreasing DF values along the path. Spectra in the gradients did not exhibit bimodal spectra as is usually observed in traditional DF domain boundaries. Time-space plots revealed clear association between gradient pattern and epicardial conduction velocity changes. Prior simulation studies predicted a gradient in activation rate during rotor drift. This gradient pattern has been observed for the first time experimentally by only using CFT, but not FFT. High-precision DF videos indicated the existence of gradient movement from one spatial location to another, smoothly instead of randomly disappearing from one location and appearing in another. The discovery of associated pseudoconduction velocity changes, and gradient patterns might suggest that dominant rotor (mother rotor) drifting plays a maintenance role only detectable by CFT and not FFT. PMID:16226093

  10. A Position- and Velocity-Sensorless Control for Synchronous Reluctance Motor with Disturbance Observer Using High Frequency Voltages and Currents

    NASA Astrophysics Data System (ADS)

    Tamaoki, Masakazu; Tomita, Mutuwo; Chen, Zhiqian; Doki, Shinji; Okuma, Shigeru

    Synchronous reluctance motors (SynRMs) are characterized by their sturdiness, and several sensorless control methods of SynRMs have been proposed. In their methods, flux is estimated and the rotor position is estimated from the flux. The induced voltages for flux estimation are small at low speed. In this paper, new position estimation method is proposed using the disturbance observer based on high frequency currents. Simulation results show that the proposed system is very useful.

  11. [Electrophysiologic analysis of the lumbosacral radiculopathy using nerve root conduction velocity (NRCV) and cauda equina action potentials (CEAP)].

    PubMed

    Kamitani, K; Baba, H; Shimada, T; Chiba, H

    1993-07-01

    Nerve root conduction velocity (NRCV) and cauda equina action potential (CEAP) have been measured to assess the severity of lumbosacral radiculopathy, the level-specific diagnosis of the symptomatic roots, and to predict the outcome. This study included 71 patients (40 males, 31 females, average age of 54 years at the time of surgery) who underwent decompressive surgery for lumbar radiculopathy. The NRCV and CEAP were directly measured during the operation. The NRCV decreased significantly with progression of radicular symptoms. The NRCV showed a marked reduction in the nerve roots of the patients with a two years or longer history of radicular symptoms; or those with compression of the nerve roots on the imaging examinations; or nerve roots that were considered to have been subjected to persistent compression over a prolonged period with severe inflammation and adhesions. Multivariative analyses suggested that the NRCV correlated closely to the postoperative neurologic recovery, and the outcome of the lumbosacral radiculopathy could be predicted to some extent by measurements of NRCV. The level-specific diagnosis of the radiculopathy could be determined when the CEAP showed a more than 30% left-right potentials difference. PMID:8409633

  12. Coupled Brownian motors: Anomalous hysteresis and zero-bias negative conductance

    NASA Astrophysics Data System (ADS)

    Reimann, P.; Kawai, R.; Van den Broeck, C.; Hänggi, P.

    1999-03-01

    We introduce a model of interacting Brownian particles in a symmetric, periodic potential that undergoes a noise-induced non-equilibrium phase transition. The associated spontaneous symmetry breaking entails a ratchet-like transport mechanism. In response to an external force we identify several novel features; among the most prominent being a zero-bias negative conductance and a prima facie counterintuitive, anomalous hysteresis.

  13. 49 CFR 240.115 - Criteria for consideration of prior safety conduct as a motor vehicle operator.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... conviction for, or completed state action to cancel, revoke, suspend, or deny a motor vehicle drivers license... substance; (2) A conviction for, or completed state action to cancel, revoke, suspend, or deny a motor... as a motor vehicle operator. 240.115 Section 240.115 Transportation Other Regulations Relating...

  14. 49 CFR 240.115 - Criteria for consideration of prior safety conduct as a motor vehicle operator.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... conviction for, or completed state action to cancel, revoke, suspend, or deny a motor vehicle drivers license... substance; (2) A conviction for, or completed state action to cancel, revoke, suspend, or deny a motor... as a motor vehicle operator. 240.115 Section 240.115 Transportation Other Regulations Relating...

  15. 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. PMID:18317743

  16. Glycemic control and nerve conduction abnormalities in non-insulin-dependent diabetic subjects.

    PubMed

    Graf, R J; Halter, J B; Pfeifer, M A; Halar, E; Brozovich, F; Porte, D

    1981-03-01

    The influence of therapy of hyperglycemia on the progression of diabetic neuropathy is unclear. We studied variables of glycemia and motor and sensory nerve conduction velocity in a group of 18 non-insulin-dependent diabetic subjects before and after institution of diabetes therapy. Diabetes therapy significantly reduced variables of glycemia after 1, 3, 6, and 12 months. Conduction velocity of the median motor nerve was improved from baseline at each time tested during treatment. In addition, peroneal and tibial motor nerve conduction velocities improved in patients whose levels of hyperglycemia were lowered. Moreover, extent of improvement of conduction velocity of some motor nerves was related to the degree of reduction of hyperglycemia. Sensory nerve conduction velocity was not altered by diabetes therapy. These findings support the hypothesis of a metabolic component to diabetic neuropathy and suggest that optimal glycemic control may be beneficial to patients with this disorder. PMID:7013592

  17. 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

  18. 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).

  19. The Connexin40A96S mutation from a patient with atrial fibrillation causes decreased atrial conduction velocities and sustained episodes of induced atrial fibrillation in mice.

    PubMed

    Lübkemeier, Indra; Andrié, René; Lickfett, Lars; Bosen, Felicitas; Stöckigt, Florian; Dobrowolski, Radoslaw; Draffehn, Astrid M; Fregeac, Julien; Schultze, Joachim L; Bukauskas, Feliksas F; Schrickel, Jan Wilko; Willecke, Klaus

    2013-12-01

    Atrial fibrillation (AF) is the most common type of cardiac arrhythmia and a major cause of stroke. In the mammalian heart the gap junction proteins connexin40 (Cx40) and connexin43 (Cx43) are strongly expressed in the atrial myocardium mediating effective propagation of electrical impulses. Different heterozygous mutations in the coding region for Cx40 were identified in patients with AF. We have generated transgenic Cx40A96S mice harboring one of these mutations, the loss-of-function Cx40A96S mutation, as a model for atrial fibrillation. Cx40A96S mice were characterized by immunochemical and electrophysiological analyses. Significantly reduced atrial conduction velocities and strongly prolonged episodes of atrial fibrillation were found after induction in Cx40A96S mice. Analyses of the gating properties of Cx40A96S channels in cultured HeLa cells also revealed significantly lower junctional conductance and enhanced sensitivity voltage gating of Cx40A96S in comparison to Cx40 wild-type gap junctions. This is caused by reduced open probabilities of Cx40A96S gap junction channels, while single channel conductance remained the same. Similar to the corresponding patient, heterozygous Cx40A96S mice revealed normal expression levels and localization of the Cx40 protein. We conclude that heterozygous Cx40A96S mice exhibit prolonged episodes of induced atrial fibrillation and severely reduced atrial conduction velocities similar to the corresponding human patient. PMID:24060583

  20. TMEM43 Mutation p.S358L Alters Intercalated Disc Protein Expression and Reduces Conduction Velocity in Arrhythmogenic Right Ventricular Cardiomyopathy

    PubMed Central

    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. PMID:25343256

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

    PubMed

    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 2m length were performed with initial Darcy injection velocities (q0) of 0.5, 1.5, and 4.1m/h and elemental iron input concentrations (Fe(0)in) of 0.6, 10, and 17g/L. Concentrations of Fe(0) in the sand were determined by magnetic susceptibility scans, which provide detailed Fe(0) 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 Fe(0) concentrations of about 14-18g/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

  2. 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

  3. Nerve conduction abnormalities in untreated maturity-onset diabetes: relation to levels of fasting plasma glucose and glycosylated hemoglobin.

    PubMed

    Graf, R J; Halter, J B; Halar, E; Porte, D

    1979-03-01

    The role of metabolic abnormalities in the development of diabetic neuropathy is controversial. To investigate the influence of hyperglycemia on nerve conduction, we studied 20 untreated maturity-onset diabetic patients and 23 normal control subjects of similar age. Nerve conduction velocity of motor (median, peroneal, and tibial) and sensory (median and sural) nerves in diabetic patients was significantly slowed and H-reflex latency time prolonged. Levels of fasting plasma glucose in diabetic subjects were correlated with slowed motor conduction velocity of the median, peroneal, and tibial nerves but not with sensory nerve conduction velocities. Levels of glycosylated hemoglobin, an index of long-term glycemia, were correlated with slowing of peroneal motor conduction velocity in diabetic patients. These associations could not be explained by patient age or duration of diabetes. These findings suggest that the degree of hyperglycemia of untreated maturity-onset diabetes contributes to the motor nerve conduction abnormalities in this disease. PMID:426398

  4. Conduct overall test operations and evaluate two Doppler systems to detect, track and measure velocities in aircraft wake vortices

    NASA Technical Reports Server (NTRS)

    Wilson, D. J.; Krause, M. C.; Craven, C. E.; Edwards, B. B.; Coffey, E. W.; Huang, C. C.; Jetton, J. L.; Morrison, L. K.

    1974-01-01

    A program plan for system evaluation of the two-dimensional Scanning Laser Doppler System (SLDS) is presented. In order to meet system evaluation and optimization objectives the following tests were conducted: (1) noise tests; (2) wind tests; (3) blower flowfield tests; (4) single unit (1-D) flyby tests; and (5) dual unit (2-D) flyby tests. Test results are reported. The final phase of the program included logistics preparation, equipment interface checkouts, and data processing. It is concluded that the SLDS is capable of accurately tracking aircraft wake vortices from small or large aircraft, and in any type of weather.

  5. 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

  6. 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

    Ishibashi, Fukashi; Kojima, Rie; Taniguchi, Miki; Kosaka, Aiko; Uetake, Harumi; Tavakoli, Mitra

    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

  7. 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

  8. Motor unit remodelling in Duchenne muscular dystrophy. Electrophysiological assessment.

    PubMed

    Cruz Martínez, A; López-Terradas, J M

    1992-01-01

    Conventional EMG, motor and sensory conduction velocities, averaging analysis of MUPs, SFEMG, and muscle fiber conduction velocity in situ were performed in 14 boys with Duchenne muscular dystrophy (DD) aged 5 to 11 years. MUPs parameters study showed a striking increment of long duration MUPs followed by satellites and increase of polyphasic potentials of variable duration. The main findings in SFEMG examination were increment in fiber density of the motor unit, large MISI and presence of complex potentials of long duration in all patients. Muscle fiber conduction velocity in situ was significantly slower than in controls, with significant decrease in minimum conduction and increased variability (large SD) in propagation velocity values. Low conduction velocity of muscle fibers, long duration of polyphasics and MUPs followed by satellites, and large MISI were significantly related. These findings support the hypotheses which have suggested that the motor unit remodelling in DD is mainly myogenic. The abnormalities in muscle fiber conduction velocity in situ reflect an increased diameter variation of muscle fibers consistent with splitting fibers, small groups of regenerating and necrotic fibers, and fiber diameter variation found in histological studies. Thus, increased variability in fiber diameter may be the cause of complex and long duration MUPs in DD. PMID:1526215

  9. Pore Velocity Estimation Uncertainties

    NASA Astrophysics Data System (ADS)

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

    1982-08-01

    Geostatistical data analysis techniques were used to stochastically model the spatial variability of groundwater pore velocity in a potential waste repository site. Kriging algorithms were applied to Hanford Reservation data to estimate hydraulic conductivities, hydraulic head gradients, and pore velocities. A first-order Taylor series expansion for pore velocity was used to statistically combine hydraulic conductivity, hydraulic head gradient, and effective porosity surfaces and uncertainties to characterize the pore velocity uncertainty. Use of these techniques permits the estimation of pore velocity uncertainties when pore velocity measurements do not exist. Large pore velocity estimation uncertainties were found to be located in the region where the hydraulic head gradient relative uncertainty was maximal.

  10. Modulatory effects of oligodendrocytes on the conduction velocity of action potentials along axons in the alveus of the rat hippocampal CA1 region.

    PubMed

    Yamazaki, Yoshihiko; Hozumi, Yasukazu; Kaneko, Kenya; Sugihara, Toshimichi; Fujii, Satoshi; Goto, Kaoru; Kato, Hiroshi

    2007-11-01

    Like neurons and astrocytes, oligodendrocytes have a variety of neurotransmitter receptors and ion channels. However, except for facilitating the rapid conduction of action potentials by forming myelin and buffering extracellular K(+), little is known about the direct involvement of oligodendrocytes in neuronal activities. To investigate their physiological roles, we focused on oligodendrocytes in the alveus of the rat hippocampal CA1 region. These cells were found to respond to exogenously applied glutamate by depolarization through N-methyl-D-aspartate (NMDA) receptors and non-NMDA receptors. Electrical stimulation of the border between the alveus and stratum oriens evoked inward currents through several routes involving glutamate receptors and inward rectifier K(+) channels. Moreover, electrical stimulation resembling in vivo activity evoked long-lasting depolarization. To examine the modulatory effects of oligodendrocytes on neuronal activities, we performed dual, whole-cell recording on CA1 pyramidal neurons and oligodendrocytes. Direct depolarization of oligodendrocytes shortened the latencies of action potentials evoked by antidromic stimulation. These results indicate that oligodendrocytes increase the conduction velocity of action potentials by a mechanism additional to saltatory conduction, and that they have active roles in information processing in the brain. PMID:18634564

  11. 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. PMID:24774228

  12. Experimental determination of electrical conductivity during deformation of melt-bearing olivine aggregates: Implications for electrical anisotropy in the oceanic low velocity zone

    NASA Astrophysics Data System (ADS)

    Caricchi, Luca; Gaillard, Fabrice; Mecklenburgh, Julian; Le Trong, Emmanuel

    2011-02-01

    A novel experimental setup was used to measure in-situ variations of electrical conductivity (EC) during deformation in torsion (simple shear) at 300 MPa confining pressure and temperatures between 873 and 1473 K. This setup is designed to test if deformation of partially molten systems can produce electrical anisotropy. The motivation for this study comes from the observation that the Lithosphere-Asthenosphere Boundary (LAB) at mid-ocean ridges and in particular at the East Pacific Rise is strongly electrically anisotropic. In an initial set of calibration experiments, the variation of EC with temperature (873-1473 K) was determined for Carrara marble, Åheim dunite and basalt-bearing olivine aggregates. EC was then monitored during deformation experiments at 1473 K and measured in the frequency range between 6 MHz and 1 Hz. The electrical response of the different materials tested as a function of frequency, changes significantly depending on the presence, absence, proportion and distribution of melt contained in the specimen. Melt-free samples show a single conduction mechanism whereas melt-bearing samples display two conduction mechanisms linked in series, reflecting the contribution of isolated and connected melt. Impedance was measured along the sample radius, in a direction parallel to the shear gradient inherent in torsion experiments. During the tests, increasing values of the impedance measured suggest that the long range melt connectivity decreases radially, and melt drains from low to high shear stress regions. The conductivity, calculated from impedance measurements, is low and comparable to values measured along mid-ocean ridges. We suggest that electrical anisotropy of the LAB reflects an alternation of melt-enriched and melt-depleted channels elongated in the spreading direction possibly induced by spreading velocity gradients along the ridge. This implies that the observed electrical anisotropy reveals larger scale processes than strain

  13. Conduction aphasia, sensory-motor integration, and phonological short-term memory - an aggregate analysis of lesion and fMRI data.

    PubMed

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

    2011-12-01

    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

  14. 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).

  15. 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

  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. Motor neuron abiotrophy in a saluki.

    PubMed

    Kent, M; Knowles, K; Glass, E; deLahunta, A; Braund, K; Alroy, J

    1999-01-01

    A nine-week-old saluki puppy was presented to Tufts University School of Veterinary Medicine for progressive, generalized weakness and bilateral forelimb deformities. Examination suggested a diffuse neuromuscular lesion. Cerebrospinal fluid (CSF) analysis showed normal nucleated cell count and protein level; however, many macrophages had vacuolated cytoplasm. Electromyography (EMG) recordings suggested denervation in paraspinal and appendicular muscles. Tibial motor nerve conduction velocity was normal, but direct evoked muscle potential had reduced amplitude. Histopathology revealed diffuse, symmetrical, degenerative motor neuronopathy of the ventral horn of the spinal cord with associated lesions in nerves and muscles. Histopathology was consistent with an abiotrophy that was likely inherited. PMID:10493421

  18. 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.

  19. 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…

  20. 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. PMID:25083853

  1. A new instrumentation for particle velocity and velocity related measurements under water

    NASA Astrophysics Data System (ADS)

    Zhu, Weijia

    This dissertation investigates the capability of a new instrument for small particle velocity measurement and velocity related signal analysis in an underwater environment. This research started from the laser beam quality test, which was performed in air. It was conducted mainly by means of an optical fiber sensor combined with a computer controlled stepping motor as well as two other methods, edge detection and needle-tip scattering. The stepping motor offers a constant velocity to the fiber sensor, so that the beam separation can be accurately measured by using the constant velocity value and the transit time determined by the cross correlation function of two digital signals. Meanwhile, information of the beam intensity profile, the parallelism of the two beams and the in-air beam widths can also be obtained in the test. By using the calibrated beam separation of the ribbon pair in the beam quality test, particle velocity measurements are carried out based on the relation between velocity, displacement and time in a 500-liter open water tank. The time delay for a particle crossing over the two ribbons in sequence is obtained by computing the cross correlation of the two signals. In fact, the time delay is actually a statistical mean value of many particles that cross over the ribbons in a short time. So is the measured velocity. The third part of this research is the practical study on pulse shape analysis based on the data sets of the velocity measurement. Several computer programs are developed to explore the pulse height distribution in a data set, to study the pulse degeneration, the relationship between the pulse width and the velocity, and the in-water beam width information. Some important reference materials are displayed in the appendices such as the fundamentals of the cross correlation and auto correlation, three main MATLAB programs developed for this research, the theoretical analysis of particle diffraction.

  2. Sensory and motor neuropathy in a Border Collie.

    PubMed

    Harkin, Kenneth R; Cash, Walter C; Shelton, G Diane

    2005-10-15

    A 5-month-old female Border Collie was evaluated because of progressive hind limb ataxia. The predominant clinical findings suggested a sensory neuropathy. Sensory nerve conduction velocity was absent in the tibial, common peroneal, and radial nerves and was decreased in the ulnar nerve; motor nerve conduction velocity was decreased in the tibial, common peroneal, and ulnar nerves. Histologic examination of nerve biopsy specimens revealed considerable nerve fiber depletion; some tissue sections had myelin ovoids, foamy macrophages, and axonal degeneration in remaining fibers. Marked depletion of most myelinated fibers within the peroneal nerve (a mixed sensory and motor nerve) supported the electrodiagnostic findings indicative of sensorimotor neuropathy. Progressive deterioration in motor function occurred over the following 19 months until the dog was euthanatized. A hereditary link was not established, but a littermate was similarly affected. The hereditary characteristic of this disease requires further investigation. PMID:16266014

  3. Nerve conduction and electromyography studies.

    PubMed

    Kane, N M; Oware, A

    2012-07-01

    Nerve conduction studies (NCS) and electromyography (EMG), often shortened to 'EMGs', are a useful adjunct to clinical examination of the peripheral nervous system and striated skeletal muscle. NCS provide an efficient and rapid method of quantifying nerve conduction velocity (CV) and the amplitude of both sensory nerve action potentials (SNAPs) and compound motor action potentials (cMAPs). The CV reflects speed of propagation of action potentials, by saltatory conduction, along large myelinated axons in a peripheral nerve. The amplitude of SNAPs is in part determined by the number of axons in a sensory nerve, whilst amplitude of cMAPs reflects integrated function of the motor axons, neuromuscular junction and striated muscle. Repetitive nerve stimulation (RNS) can identify defects of neuromuscular junction (NMJ) transmission, pre- or post-synaptic. Needle EMG examination can detect myopathic changes in muscle and signs of denervation. Combinations of these procedures can establish if motor and/or sensory nerve cell bodies or peripheral nerves are damaged (e.g. motor neuronopathy, sensory ganglionopathy or neuropathy), and also indicate if the primary target is the axon or the myelin sheath (i.e. axonal or demyelinating neuropathies). The distribution of nerve damage can be determined as either generalised, multifocal (mononeuropathy multiplex) or focal. The latter often due to compression at the common entrapment sites (such as the carpal tunnel, Guyon's canal, cubital tunnel, radial groove, fibular head and tarsal tunnel, to name but a few of the reported hundred or so 'entrapment neuropathies'). PMID:22614870

  4. Computer method for the analysis of evoked motor unit potentials. 2. Duchenne, limb-girdle, facioscapulohumeral and myotonic muscular dystrophies.

    PubMed Central

    Ballantyne, J P; Hansen, S

    1975-01-01

    Single motor unit potentials recorded from surface electrodes over the extensor digitorum brevis muscle and evoked by stimulation of the anterior tibial nerve at the ankle were obtained by a computer subtraction method. Their latencies, durations, amplitudes, and areas were measured in control subjects and patients with Duchenne, limb-girdle, facioscapulohumeral, and myotonic muscular dystrophy. Lateral popliteal motor nerve conduction velocities were also recorded. In the muscular dystrophies there was a significant increase in both the latencies and durations of motor unit potentials, the latter in notable contrast with the findings of conventional needle electromyography. Fastest motor conduction velocities were significantly reduced in the limb-girdle, facioscapulohumeral, and myotonic muscular dystrophy patients, while the shortest distal motor latencies were significantly prolonged in these patients and those with Duchenne muscular dystrophy. The results support the presence of a definitive neurogenic influence in the muscular dystrophies. PMID:1151411

  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. 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.

  7. Pulsewidth modulated speed control of brushless dc motors

    NASA Astrophysics Data System (ADS)

    Askinas, A. A.

    1984-09-01

    Until recently, few alternatives existed for the use of hydraulic and pneumatic actuators in primary flight control applications. With the advent of the samarium-cobalt permanent magnet brushless DC motor, consideration must now be given to the utilization of an electromechanical actuator in missiles which require significant maneuvering capability and hence, greater torques. This thesis investigates the theory and techniques of pulse width modulator speed control of brushless DC motors. After describing basic pulse width modulation (PWM) concepts, two constant velocity control schemes are presented: current feedback and a limit cycle scheme. By calculating the motor form factor (a figure of merit for power losses in the switching transistors which comprise the PWM network), the relative worth of each scheme is then evaluated. An in depth study is conducted of the limit cycle approach, with an emphasis on the power loss reductions obtained through the reduction of the velocity limit settings.

  8. Lateral spike conduction velocity in the visual cortex affects spatial range of synchronization and receptive field size without visual experience: a learning model with spiking neurons.

    PubMed

    Saam, M; Eckhorn, R

    2000-07-01

    Classical receptive fields (cRF) increase in size from the retina to higher visual centers. The present work shows how temporal properties, in particular lateral spike velocity and spike input correlation, can affect cRF size and position without visual experience. We demonstrate how these properties are related to the spatial range of cortical synchronization if Hebbian learning dominates early development. For this, a largely reduced model of two successive levels of the visual cortex is developed (e.g., areas V1 and V2). It consists of retinotopic networks of spiking neurons with constant spike velocity in lateral connections. Feedforward connections between level 1 and 2 are additive and determine cRF size and shape, while lateral connections within level 1 are modulatory and affect the cortical range of synchronization. Input during development is mimicked by spike trains with spatially homogeneous properties and a confined temporal correlation width. During learning, the homogeneous lateral coupling shrinks to limited coupling structures defining synchronization and related association fields (AF). The size of level-1 synchronization fields determines the lateral coupling range of developing level-1-to-2 connections and, thus, the size of level-2 cRFs, even if the feedforward connections have distance-independent delays. AFs and cRFs increase with spike velocity in the lateral network and temporal correlation width of the input. Our results suggest that AF size of V1 and cRF size of V2 neurons are confined during learning by the temporal width of input correlations and the spike velocity in lateral connections without the need of visual experience. During learning from visual experience, a similar influence of AF size on the cRF size may be operative at successive levels of processing, including other parts of the visual system. PMID:10933233

  9. Multifocal motor neuropathy.

    PubMed

    Muley, Suraj Ashok; Parry, Gareth J

    2012-09-01

    Multifocal motor neuropathy (MMN) was first described in 1988 as a purely motor neuropathy affecting multiple motor nerves. The diagnosis was based entirely on demonstrating electrophysiological evidence of a conduction block (CB) that selectively affected motor axons, with sparing of sensory axons even through the site of motor CB. Subsequently, a similar disorder was reported but with absence of demonstrable CB on routine nerve conduction studies and there is still some debate as to whether MMN without CB is related to MMN. MMN is thought to be an inflammatory neuropathy related to an immune attack on motor nerves. The conventional hypothesis is that the primary pathology is segmental demyelination, but recent research raises the possibility of a primary axonopathy. Anti-GM1 antibodies can be found in some patients but it is unclear whether these antibodies are pathogenic. Intravenous immunoglobulin is the mainstay of treatment but other immunosuppressive treatments can also be effective. PMID:22743043

  10. 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. PMID:24411324

  11. 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.

  12. Hybrid Rocket Motor Test

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Stennis Space Center conducts a test on a hybrid rocket motor fed by a liquid oxygen turbopump. The test occurred at the E-1 test facility. The test was believed to be the first of its kind in the world.

  13. Multimotor Driven Cargos: From Single Motor under Load to the Role of Motor-Motor Coupling.

    PubMed

    Peker, Itay; Granek, Rony

    2016-07-01

    Motor proteins constitute an essential part of the cellular machinery. They have been the subject of intensive studies in the past two decades. Yet, when several motors simultaneously carry a single cargo, the effect of motor-motor coupling, such as mutual stalling and jamming, remains unclear. We commence by constructing a general model for single motor motion, which is a product of a derived load-dependent expression and a phenomenological motor specific function. Forming the latter according to recent single molecule measurements for a given load, the model correctly predicts the motor full step-size distribution for all other measured loads. We then use our proposed model to predict transport properties of multimotor complexes, with particular attention to 1-dimensional constructs with variable flexibility, motor density, and number of motors: (i) a chain of motors connected by springs, a recently studied construction of a pair, and (ii) an array of motors all connected by identical springs to a stiff rod, which is essentially a mirror image of standard gliding motility assays. In both systems, and for any number of carrying motors, we find that, while low flexibility results in a strongly damped velocity, increased flexibility renders an almost single motor velocity. Comparing our model based simulations to recent gliding assays we find remarkable qualitative agreement. We also demonstrate consistency with other multimotor motility assays. In all cases, the characteristic spring constant, that controls the crossover behavior between high and low velocity regimes, is found to be the stalling force divided by the mean step size. We conjecture that this characteristic spring constant can serve as a tool for engineering multimotor complexes. PMID:27044876

  14. Intercostal nerve conduction study in man.

    PubMed Central

    Pradhan, S; Taly, A

    1989-01-01

    A new surface technique for the conduction study of the lower intercostal nerves has been developed and applied to 30 normal subjects. The problem of the short available nerve segment of the intercostal nerves and the bizzare compound motor action potential (CMAP) of inconsistent latency while recording over the intercostal muscles, is overcome by applying recording electrodes over the rectus abdominis muscle and stimulating the nerves at two points at a fair distance away. With the use of multiple recording sites over the rectus abdominis, the motor points for different intercostal nerves were delineated. CMAP of reproducible latencies and waveforms with sharp take-off points were obtained. Conduction velocity of the intercostal nerves could be determined. PMID:2526200

  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. The induction motor

    NASA Astrophysics Data System (ADS)

    Redinz, José Arnaldo

    2015-09-01

    We obtain analytical expressions for the torques and angular speed of an induction motor with a simple geometry, resembling the geometry of the first induction motor investigated by Arago in 1824. The rotor is a conducting disc rotating between the magnetic poles of two off-axis solenoids, displaced in space by 90^\\circ from each other. We apply our results to discuss a theory for the ubiquitous electromechanical watt-hour meter. For comparison of the theoretical result for the angular speed with measurements, we propose a simple experiment in which an induction motor with an aluminum disc rotor is constructed.

  17. Changes in corticospinal facilitation of lower limb spinal motor neurons after spinal cord lesions.

    PubMed Central

    Brouwer, B; Bugaresti, J; Ashby, P

    1992-01-01

    The projections from the cortex to the motor neurons of lower limb muscles were examined in 33 normal subjects and 16 patients with incomplete spinal cord lesions. Corticospinal neurons were excited by transcranial magnetic stimulation and the effects on single spinal motor neurons determined from peristimulus time histograms (PSTHs) of single tibialis anterior (TA) and soleus (SOL) motor units. In normal subjects magnetic stimulation produced a short latency facilitation of TA motor units but had little or no effect on SOL motor units. In the patients with spinal cord lesions magnetic stimulation also produced facilitation of TA but not SOL motor units; however, the mean latency of the TA facilitation was significantly longer (by about 14 ms) in the patient group. The F wave latencies were normal in all patients tested, suggesting that central rather than peripheral conduction was slowed. The duration of the period of increased firing probability (in TA motor units) was also significantly longer in the patients with spinal cord lesions. These changes may reflect the slowing of conduction and dispersal of conduction velocities in the corticospinal pathways as a consequence of the spinal cord lesion. No significant correlations were found between the delay of the TA facilitation and the clinical deficits in this group of patients. Images PMID:1312579

  18. 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.

  19. Comparison of short-term effects of insulin and essential fatty acids on the slowed nerve conduction of streptozotocin diabetes in rats.

    PubMed

    Julu, P O; Mutamba, A

    1991-11-01

    Early effects of insulin and essential fatty acids on nerve conduction were studied. Insulin-dependent diabetes was induced in rats using streptozocin (65 mg/kg, i.p.); control rats were treated with buffer. Five weeks later, diabetic rats were divided into 5 groups. Two groups were given oral essential fatty acids (75% linoleic and 9% gamma-linolenic acids) for a further 3 and 5 days, respectively. Two other groups received subcutaneous insulin for a further 3 or 5 days. A group of diabetic rats were left without further treatment. Motor nerve conduction velocity was measured terminally in all rats by stimulating the sciatic nerve and recording EMGs in the gastrocnemius muscle under urethane anaesthesia. Sensory nerve conduction velocity was measured by stimulating and recording from the saphenous nerve trunk. Diabetic rats had significantly slowed motor and sensory nerve conduction velocities after 5 weeks (16.7%, P less than 0.001). Three days treatment with either insulin or fatty acids corrected the slowed motor nerve conduction velocity to a normal level. Conduction velocity in myelinated sensory nerves was still 10% slower in diabetic rats treated with insulin for 3 days (P less than 0.01). It was above the control level by 11% in diabetic rats treated with fatty acids for the same period (P less than 0.01). Conduction velocities in both sensory and motor nerves were normal in diabetic rats treated with either insulin or fatty acids for 5 days. It was concluded that both insulin and essential fatty acids had early effects on nerve conduction in diabetic rats. The speed of their actions, and the magnitudes of responses were different in sensory and motor nerves. PMID:1663993

  20. 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.

  1. 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.

  2. 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. PMID:22377850

  3. Motor Starters

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The power factor controller (PFC) was invented by a NASA engineer. It matches voltage with a motor's actual need by sensing shifts in the relationship between voltage and current flow. With the device, power can be trimmed as much as 65%. Intellinet adopted this technology and designed "soft start" and "load-responsive" control modes to start engines gradually and recycle voltage without reducing motor speed. Other features are lower motor heat and faster fault identification.

  4. 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.

  5. Transport of Beads by Several Kinesin Motors

    PubMed Central

    Beeg, Janina; Klumpp, Stefan; Dimova, Rumiana; Gracià, Rubèn Serral; Unger, Eberhard; Lipowsky, Reinhard

    2008-01-01

    The movements of beads pulled by several kinesin-1 (conventional kinesin) motors are studied both theoretically and experimentally. While the velocity is approximately independent of the number of motors pulling the beads, the walking distance or run-length is strongly increased when more motors are involved. Run-length distributions are measured for a wide range of motor concentrations and matched to theoretically calculated distributions using only two global fit parameters. In this way, the maximal number of motors pulling the beads is estimated to vary between two and seven motors for total kinesin concentrations between 0.1 and 2.5 μg/ml or between 0.27 and 6.7 nM. In the same concentration regime, the average number of pulling motors is found to lie between 1.1 and 3.2 motors. PMID:17872957

  6. Transport of beads by several kinesin motors.

    PubMed

    Beeg, Janina; Klumpp, Stefan; Dimova, Rumiana; Gracià, Rubèn Serral; Unger, Eberhard; Lipowsky, Reinhard

    2008-01-15

    The movements of beads pulled by several kinesin-1 (conventional kinesin) motors are studied both theoretically and experimentally. While the velocity is approximately independent of the number of motors pulling the beads, the walking distance or run-length is strongly increased when more motors are involved. Run-length distributions are measured for a wide range of motor concentrations and matched to theoretically calculated distributions using only two global fit parameters. In this way, the maximal number of motors pulling the beads is estimated to vary between two and seven motors for total kinesin concentrations between 0.1 and 2.5 microg/ml or between 0.27 and 6.7 nM. In the same concentration regime, the average number of pulling motors is found to lie between 1.1 and 3.2 motors. PMID:17872957

  7. 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.

  8. Retention of Motor Skills: Review.

    ERIC Educational Resources Information Center

    Schendel, J. D.; And Others

    A summary of an extensive literature survey deals with the variables known or suspected to affect the retention of learned motor behaviors over lengthy no-practice intervals. Emphasis was given to research conducted by or for the military. The variables that may affect the retention of motor skills were dichotomized into task variables and…

  9. 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.

  10. 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. PMID:27125560

  11. 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. PMID:21555118

  12. Prediction of Pseudo relative velocity response spectra at Yucca Mountain for underground nuclear explosions conducted in the Pahute Mesa testing area at the Nevada testing site; Yucca Mountain Site Characterization Project

    SciTech Connect

    Phillips, J.S.

    1991-12-01

    The Yucca Mountain Site Characterization Project (YMP), managed by the Office of Geologic Disposal of the Office of Civilian Radioactive Waste Management of the US Department of Energy, is examining the feasibility of siting a repository for commercial, high-level nuclear wastes at Yucca Mountain on and adjacent to the Nevada Test Site (NTS). This work, intended to extend our understanding of the ground motion at Yucca Mountain resulting from testing of nuclear weapons on the NTS, was funded by the Yucca Mountain project and the Military Applications Weapons Test Program. This report summarizes one aspect of the weapons test seismic investigations conducted in FY88. Pseudo relative velocity response spectra (PSRV) have been calculated for a large body of surface ground motions generated by underground nuclear explosions. These spectra have been analyzed and fit using multiple linear regression techniques to develop a credible prediction technique for surface PSRVs. In addition, a technique for estimating downhole PSRVs at specific stations is included. A data summary, data analysis, prediction development, prediction evaluation, software summary and FORTRAN listing of the prediction technique are included in this report.

  13. 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.

  14. Motor Controller

    NASA Technical Reports Server (NTRS)

    1988-01-01

    M.H. Marks Enterprises' Power Factor Controller (PFC) matches voltage with motor's actual need. Plugged into a motor, PFC continuously determines motor load by sensing shifts between voltage and current flow. When it senses a light load, it cuts voltage to the minimum needed. It offers potential energy savings ranging from eight percent up to 65 percent depending on the application. Myles Marks started out with the notion of writing an article for Popular Electronics magazine at the same time offering to furnish kits to readers interested in assembling PFC's. Within two weeks from publication he had orders for 500 kits and orders are still coming three years later.

  15. Chaotic motors

    NASA Astrophysics Data System (ADS)

    Laroche, C.; Labbé, R.; Pétrélis, F.; Fauve, S.

    2012-02-01

    We show that electric motors and dynamos can be used to illustrate most elementary instabilities or bifurcations discussed in courses on nonlinear oscillators and dynamical systems. These examples are easier to understand and display a richer behavior than the ones commonly used from mechanics, electronics, hydrodynamics, lasers, chemical reactions, and population dynamics. In particular, an electric motor driven by a dynamo can display stationary, Hopf, and codimension-two bifurcations by tuning the driving speed of the dynamo and the electric current in the stator of the electric motor. When the dynamo is driven at constant torque instead of constant rotation rate, chaotic reversals of the generated current and of the angular rotation of the motor are observed. Simple deterministic models are presented which capture the observed dynamical regimes.

  16. Molecular Motors: Power Strokes Outperform Brownian Ratchets.

    PubMed

    Wagoner, Jason A; Dill, Ken A

    2016-07-01

    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. PMID:27136319

  17. Force generation by cellular motors.

    PubMed

    Wanka, Friedrich; Van Zoelen, Everardus J J

    2003-01-01

    Cell motility processes in non-muscle cells depend on the activity of motor proteins that bind to either microtubules or actin filaments. From presently available data it must be concluded that the driving force is generated by transient interaction of the respective motors with microtubules or actin filaments which then activates the binding and hydrolysis of ATP. This reaction results in an abrupt discharge of the motor molecule, the direction of which is determined by the spatial orientation of its binding to the helical and polar vehicle. The latter is thereby propelled in its length direction and simultaneously undergoes an axial rotation, while the expelled motor exerts an oppositely directed current in the surrounding fluid, comparable to jet propulsion. Force production, propulsion velocities and energy requirements known from in vitro studies comply with those derived from the theory. The theory opens new ways for the understanding of cellular activities such as particle transport, mitosis and morphodynamics. PMID:14668925

  18. 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

  19. Motor Planning.

    PubMed

    Wong, Aaron L; Haith, Adrian M; Krakauer, John W

    2015-08-01

    Motor planning colloquially refers to any process related to the preparation of a movement that occurs during the reaction time prior to movement onset. However, this broad definition encompasses processes that are not strictly motor-related, such as decision-making about the identity of task-relevant stimuli in the environment. Furthermore, the assumption that all motor-planning processes require processing time, and can therefore be studied behaviorally by measuring changes in the reaction time, needs to be reexamined. In this review, we take a critical look at the processes leading from perception to action and suggest a definition of motor planning that encompasses only those processes necessary for a movement to be executed-that is, processes that are strictly movement related. These processes resolve the ambiguity inherent in an abstract goal by defining a specific movement to achieve it. We propose that the majority of processes that meet this definition can be completed nearly instantaneously, which means that motor planning itself in fact consumes only a small fraction of the reaction time. PMID:24981338

  20. Recovery of nerve conduction after a pneumatic tourniquet: observations on the hind-limb of the baboon1

    PubMed Central

    Fowler, T. J.; Danta, G.; Gilliatt, R. W.

    1972-01-01

    A small pneumatic cuff inflated around the knee was used to produce tourniquet paralysis in baboons. A cuff pressure of 1,000 mm Hg maintained for one to three hours produced paralysis of distal muscles lasting up to three months. Nerve conduction studies showed that most of the motor fibres to the abductor hallucis muscle were blocked at the level of the cuff and that they conducted impulses normally in their distal parts. There was a significant correlation between the duration of compression and that of the subsequent conduction block. When tested two to three weeks after the tourniquet, the amplitude of the response of m. abductor hallucis to nerve stimulation distal to the cuff was usually slightly reduced compared with the precompression figure. This was assumed to mean that a small proportion of the motor fibres had undergone Wallerian degeneration as a result of compression. Maximal motor conduction velocity was reduced in recovering nerves. It was also reduced when a cuff pressure of 500 mm Hg was used, which was insufficient to produce persistent conduction block. In such cases a reduced velocity without evidence of block could be demonstrated 24 hours after compression. Ascending nerve action potentials were recorded from the sciatic nerve in the thigh, with stimulation at the ankle. Before compression the fastest afferent fibres had a significantly higher velocity than the fastest motor fibres in the same nerve trunk. Results after compression suggested that the high-velocity afferent fibres had a susceptibililty to the procedure similar to that of the fastest motor fibres. PMID:4628467

  1. 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

  2. 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...

  3. 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.

  4. Motor-operator gearbox efficiency

    SciTech Connect

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

    1996-06-01

    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, we 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 we tested under load ran at efficiencies lower than the running efficiency (typically 50%) published by the operator manufacturer.

  5. Analysis of HB Type Vernier Motor

    NASA Astrophysics Data System (ADS)

    Suda, Hiroshi; Matsushima, Yoshitaro; Xu, Li; Anazawa, Yoshihisa

    Direct drive motors are used as actuators in numerous applications in which they must rotate at low speeds with high torque and low torque ripple. Recently, various types of vernier motor have been developed. The HB type vernier motor is one of them. The structure of rotor is the same as HB type stepping motor. Our model of HB type vernier motor has a winding as field system in the rotor, but stator has three-phase windings. Relationship between S, R and P is S ± P/2=R/2, where S, R and P are the numbers of stator and rotor slots and the number of poles. The rotor of the vernier motor moves at a sub-multiple of the angular velocity of the stator mmf. The multiplying factor is P/R. As a result of analysis, the voltage equation on the γ-δ axis of HB type vernier motor is equal to general synchronous machine. The tests were performed on the trial motor. The calculated pull-out torque agreed well with the measured values. Our model of HB type vernier motor is equivalent with the PM type vernier motor which has permanent magnets in the rotor. The result of this analysis is useful for the design of both types of vernier motor.

  6. 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.

  7. Delineating cooperative responses of processive motors in living cells

    PubMed Central

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

    2014-01-01

    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. PMID:24402168

  8. 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.

  9. 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.

  10. 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. PMID:24444652

  11. Motor Neuron Diseases

    MedlinePlus

    ... Enhancing Diversity Find People About NINDS NINDS Motor Neuron Diseases Information Page Condensed from Motor Neuron Diseases ... and Information Publicaciones en Español What are Motor Neuron Diseases? The motor neuron diseases (MNDs) are a ...

  12. Motor Neuron Diseases

    MedlinePlus

    ... called upper motor neurons ) are transmitted to nerve cells in the brain stem and spinal cord (called lower motor neurons ) and from them to particular muscles. Upper motor neurons direct the lower motor neurons ...

  13. 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

  14. Ignition Transient Calculations in the Space Shuttle Solid Rocket Motor

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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

  15. 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. PMID:26749257

  16. Correlations among autonomic, sensory, and motor neural function tests in untreated non-insulin-dependent diabetic individuals.

    PubMed

    Pfeifer, M A; Weinberg, C R; Cook, D L; Reenan, A; Halar, E; Halter, J B; LaCava, E C; Porte, D

    1985-01-01

    A well-defined group of untreated non-insulin-dependent (NIDD) subjects were evaluated to determine whether involvement of neural function measurements is generalized and symmetrical and to compare the autonomic, sensory, and motor neural measurements. After age adjustment, the sensory and motor neural function measurements were significantly slower in the diabetic group than in normal subjects (P less than 0.01). Similarly, the autonomic nervous system function measurements were also abnormal in the NIDD group (P less than 0.01). Further analysis revealed that each of the specific measurements--median motor nerve conduction velocity (NCV,P less than 0.005), peroneal motor NCV (P less than 0.005), median sensory NCV (P less than 0.005), dark-adapted pupil size after muscarinic blockade (P less than 0.02), pupillary latency time (P less than 0.02), and RR-variation after beta adrenergic blockade (P less than 0.001)--was significantly less by analysis of covariance after age adjustment in the NIDD group than in normal subjects. Thus, there was evidence of motor and sensory neural impairment in the upper and lower extremities as well as evidence of impairment of the reflex arcs involving the parasympathetic nerves to the heart and eye and the sympathetic nerves to the iris. Further analysis revealed that right and left NCV were correlated (P less than 0.01), as were the median motor and median sensory NCV (P less than 0.01), the median motor and peroneal motor NCV (P less than 0.001), and the peroneal motor and median sensory NCV (P less than 0.001). Thus, there was evidence of symmetrical upper and lower limb, as well as motor and sensory proportional involvement of large nerve fiber NCV in this group of NIDD subjects.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:4075943

  17. Median and ulnar nerve conduction determinations in the Erb's point--axilla segment in normal subjects.

    PubMed Central

    Ginzburg, M; Lee, M; Ginzburg, J; Alba, A

    1978-01-01

    Twenty-one median and 22 ulnar nerves were tested in 12 patients for motor nerve conduction velocity (MNCV) and motor nerve conduction time (MNCT) in the segments from Erb's point (N) to axilla (A) bilaterally. It was found that on this segment for both nerves, MNCV values equal to or smaller than 51 m/s or conduction times equal to or longer than 4 ms are to be considered abnormal. For comparative studies and for checking the normality of the tested nerves in their entire length, the more distally located segments in the same nerve were also tested. For diagnostic purposes, the differences between right and left MNCV or MNCT values determined in the same person on N-A segments of homologous nerves were analysed. Motor nerve conduction velocity or MNCT determinations on the N-A nerve segment are expected to replace MNCV determinations on the longer N-AE (AE=100 mm above elbow) nerve segment, which is now in use, for diagnosis of the thoracic outlet syndrome. Images PMID:660207

  18. Motor units in cross-reinnervated fast and slow twitch muscle of the cat.

    PubMed Central

    Bagust, J; Lewis, D M; Westerman, R A

    1981-01-01

    1. Isometric contractile properties of motor units were measured in cross-reinnervated fast (flexor digitorum longus) and slow (soleus) twitch muscles of the cat. All but one cross was at least 95% pure. 2. There was a reduction in the number of motor units in all muscles, but totals remained about equal in cross-reinnervated soleus and flexor digitorum longus. 3. Motor unit tensions (mean and maximum values) were higher in cross-reinnervated soleus than in cross-reinnervated flexor digitorum longus, reversing the differences between normal muscles. This was due to increases in muscle mass and in the tension developed per unit cross-sectional area. There were motor unit tensions larger and smaller than those seen in normal muscle, but the range was comparable with that seen in self-reinnervated muscle. 4. The changes in twitch time to peak of whole muscle following cross-reinnervations resulted from a change over the whole range of motor units. The conversion of soleus was less complete than that of flexor digitorum longus, and the time to peak of its fastest motor unit was twice as long as any seen in normal flexor digitorum longus. 5. In neither of the cross-reinnervated muscles were the fast contracting motor units larger than the slow contracting ones, and in cross-reinnervated soleus they were smaller. 6. Axonal conduction velocity was correlated with motor unit tension in both muscles and with twitch time to peak in cross-reinnervated flexor digitorum longus, but in all cases less clearly than in normal muscles. 7. The ratio of twitch to tetanic tension increased with increasing twitch time to peak, as in normal muscles. PMID:7277217

  19. Mechanism of Cooperative Behavior in Systems of Slow and Fast Molecular Motors

    PubMed Central

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

    2009-01-01

    Summary Two recent theoretical advances have described cargo transport by multiple identical motors and by multiple oppositely directed, but otherwise identical motors [1, 2]. Here we combine a similar theoretical approach with a simple experiment to describe the behavior 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 ∼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 behavior 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. PMID:19506764

  20. Cooperative cargo transport by several molecular motors

    PubMed Central

    Klumpp, Stefan; Lipowsky, Reinhard

    2005-01-01

    The transport of cargo particles that are pulled by several molecular motors in a cooperative manner is studied theoretically in this article. The transport properties depend primarily on the maximal number N of motor molecules that may pull simultaneously on the cargo particle. Because each motor must unbind from the filament after a finite number of steps but can also rebind to it again, the actual number of pulling motors is not constant but varies with time between zero and N. An increase in the maximal number N leads to a strong increase of the average walking distance (or run length) of the cargo particle. If the cargo is pulled by up to N kinesin motors, for example, the walking distance is estimated to be 5N–1/N micrometers, which implies that seven or eight kinesin molecules are sufficient to attain an average walking distance in the centimeter range. If the cargo particle is pulled against an external load force, this force is shared between the motors, which provides a nontrivial motor–motor coupling and a generic mechanism for nonlinear force–velocity relationships. With increasing load force, the probability distribution of the instantaneous velocity is shifted toward smaller values, becomes broader, and develops several peaks. Our theory is consistent with available experimental data and makes quantitative predictions that are accessible to systematic in vitro experiments. PMID:16287974

  1. Origin of the Low Velocity Zone

    NASA Astrophysics Data System (ADS)

    Stixrude, L. P.; Lithgow-Bertelloni, C. R.

    2014-12-01

    The origin of the low velocity zone is still not well understood, although the mechanisms responsible have important implications for the thermal evolution of the Earth and the origin of plate tectonics. The null hypothesis (a geotherm consisting of an adiabat and a conductive thermal boundary layer, and free of melt, water, and attenuation) accounts for many properties of the low velocity zone, including the depth at which the minimum velocity occurs and its variation with age, but the value of the minimum velocity is greater than that seen by seismology (the velocity deficit). Attenuation, as found in global seismic attenuation tomography, can explain much of the velocity deficit, but still leaves two features of the boundaries of the low velocity zone unexplained: an apparently abrupt upper boundary to the low velocity (G discontinuity, sometimes also associated with the "lithosphere-asthenosphere boundary"), and a high gradient zone beneath in which velocity increases with depth very rapidly. Here we show that by adding to the null hypothesis attenuation as recently measured experimentally, the entire velocity deficit is explained. Moreover, the upper boundary of the low velocity zone is remarkably abrupt, although possibly less sharp than receiver function analyses indicate. The high gradient zone is explained by variations in the entropy with depth, i.e. cooling with increasing depth at depths beneath the low velocity zone, a property of the geotherm that is expected on the basis of mantle convection simulations.

  2. 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 ...

  3. Multifocal Motor Neuropathy

    MedlinePlus

    ... Diversity Find People About NINDS NINDS Multifocal Motor Neuropathy Information Page Table of Contents (click to jump ... done? Clinical Trials Organizations What is Multifocal Motor Neuropathy? Multifocal motor neuropathy is a progressive muscle disorder ...

  4. Human spinal cord injury: motor unit properties and behaviour.

    PubMed

    Thomas, C K; Bakels, R; Klein, C S; Zijdewind, I

    2014-01-01

    Spinal cord injury (SCI) results in widespread variation in muscle function. Review of motor unit data shows that changes in the amount and balance of excitatory and inhibitory inputs after SCI alter management of motoneurons. Not only are units recruited up to higher than usual relative forces when SCI leaves few units under voluntary control, the force contribution from recruitment increases due to elevation of twitch/tetanic force ratios. Force gradation and precision are also coarser with reduced unit numbers. Maximal unit firing rates are low in hand muscles, limiting voluntary strength, but are low, normal or high in limb muscles. Unit firing rates during spasms can exceed voluntary rates, emphasizing that deficits in descending drive limit force production. SCI also changes muscle properties. Motor unit weakness and fatigability seem universal across muscles and species, increasing the muscle weakness that arises from paralysis of units, motoneuron death and sensory impairment. Motor axon conduction velocity decreases after human SCI. Muscle contractile speed is also reduced, which lowers the stimulation frequencies needed to grade force when paralysed muscles are activated with patterned electrical stimulation. This slowing does not necessarily occur in hind limb muscles after cord transection in cats and rats. The nature, duration and level of SCI underlie some of these species differences, as do variations in muscle function, daily usage, tract control and fibre-type composition. Exploring this diversity is important to promote recovery of the hand, bowel, bladder and locomotor function most wanted by people with SCI. PMID:23901835

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Cordycepin Decreases Compound Action Potential Conduction of Frog Sciatic Nerve In Vitro Involving Ca (2+) -Dependent Mechanisms.

    PubMed

    Yao, Li-Hua; Yu, Hui-Min; Xiong, Qiu-Ping; Sun, Wei; Xu, Yan-Liang; Meng, Wei; Li, Yu-Ping; Liu, Xin-Ping; Yuan, Chun-Hua

    2015-01-01

    Cordycepin has been widely used in oriental countries to maintain health and improve physical performance. Compound nerve action potential (CNAP), which is critical in signal conduction in the peripheral nervous system, is necessary to regulate physical performance, including motor system physiological and pathological processes. Therefore, regulatory effects of cordycepin on CNAP conduction should be elucidated. In this study, the conduction ability of CNAP in isolated frog sciatic nerves was investigated. Results revealed that cordycepin significantly decreased CNAP amplitude and conductive velocity in a reversible and concentration-dependent manner. At 50 mg/L cordycepin, CNAP amplitude and conductive velocity decreased by 62.18 ± 8.06% and 57.34% ± 6.14% compared with the control amplitude and conductive velocity, respectively. However, the depressive action of cordycepin on amplitude and conductive velocity was not observed in Ca(2+)-free medium or in the presence of Ca(2+) channel blockers (CdCl2/LaCl3). Pretreatment with L-type Ca(2+) channel antagonist (nifedipine/deltiazem) also blocked cordycepin-induced responses; by contrast, T-type and P-type Ca(2+) channel antagonists (Ni(2+)) failed to block such responses. Therefore, cordycepin decreased the conduction ability of CNAP in isolated frog sciatic nerves via L-type Ca(2+) channel-dependent mechanism. PMID:26078886

  10. Second messenger-mediated adjustment of bacterial swimming velocity.

    PubMed

    Boehm, Alex; Kaiser, Matthias; Li, Hui; Spangler, Christian; Kasper, Christoph Alexander; Ackermann, Martin; Kaever, Volkhard; Sourjik, Victor; Roth, Volker; Jenal, Urs

    2010-04-01

    Bacteria swim by means of rotating flagella that are powered by ion influx through membrane-spanning motor complexes. Escherichia coli and related species harness a chemosensory and signal transduction machinery that governs the direction of flagellar rotation and allows them to navigate in chemical gradients. Here, we show that Escherichia coli can also fine-tune its swimming speed with the help of a molecular brake (YcgR) that, upon binding of the nucleotide second messenger cyclic di-GMP, interacts with the motor protein MotA to curb flagellar motor output. Swimming velocity is controlled by the synergistic action of at least five signaling proteins that adjust the cellular concentration of cyclic di-GMP. Activation of this network and the resulting deceleration coincide with nutrient depletion and might represent an adaptation to starvation. These experiments demonstrate that bacteria can modulate flagellar motor output and thus swimming velocity in response to environmental cues. PMID:20303158