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Sample records for advanced reciprocating gait

  1. Modeling effects of sagittal-plane hip joint stiffness on reciprocating gait orthosis-assisted gait.

    PubMed

    Johnson, William Brett; Fatone, Stefania; Gard, Steven A

    2013-01-01

    Upright ambulation is believed to improve quality of life for persons with lower-limb paralysis (LLP). However, ambulatory orthoses for persons with LLP, like reciprocating gait orthoses (RGOs), result in a slow, exhausting gait. Increasing the hip joint stiffness of these devices may improve the efficiency of RGO-assisted gait. The small, diverse population of RGO users makes subject recruitment challenging for clinical investigations. Therefore, we developed a lower-limb paralysis simulator (LLPS) that enabled nondisabled persons to exhibit characteristics of RGO-assisted gait, thereby serving as surrogate models for research. For this study, tests were conducted to determine the effects of increased hip joint stiffness on gait of nondisabled persons walking with the LLPS. A motion capture system, force plates, and spirometer were used to measure the hip flexion, crutch ground reaction forces (GRFs), and oxygen consumption of subjects as they walked with four different hip joint stiffness settings. Increasing the hip joint stiffness decreased hip flexion during ambulation but did not appear to affect the crutch GRFs. Walking speed was observed to initially increase with increases in hip joint stiffness, and then decrease. These findings suggest that increasing hip joint stiffness may increase walking speed for RGO users.

  2. ADVANCED RECIPROCATING COMPRESSION TECHNOLOGY (ARCT)

    SciTech Connect

    Danny M. Deffenbaugh; Klaus Brun; Ralph E. Harris; J. Pete Harrell; Robert J. Mckee; J. Jeffrey Moore; Steven J. Svedeman; Anthony J. Smalley; Eugene L. Broerman; Robert A Hart; Marybeth G. Nored; Ryan S. Gernentz; Shane P. Siebenaler

    2005-12-01

    The U.S. natural gas pipeline industry is facing the twin challenges of increased flexibility and capacity expansion. To meet these challenges, the industry requires improved choices in gas compression to address new construction and enhancement of the currently installed infrastructure. The current fleet of installed reciprocating compression is primarily slow-speed integral machines. Most new reciprocating compression is and will be large, high-speed separable units. The major challenges with the fleet of slow-speed integral machines are: limited flexibility and a large range in performance. In an attempt to increase flexibility, many operators are choosing to single-act cylinders, which are causing reduced reliability and integrity. While the best performing units in the fleet exhibit thermal efficiencies between 90% and 92%, the low performers are running down to 50% with the mean at about 80%. The major cause for this large disparity is due to installation losses in the pulsation control system. In the better performers, the losses are about evenly split between installation losses and valve losses. The major challenges for high-speed machines are: cylinder nozzle pulsations, mechanical vibrations due to cylinder stretch, short valve life, and low thermal performance. To shift nozzle pulsation to higher orders, nozzles are shortened, and to dampen the amplitudes, orifices are added. The shortened nozzles result in mechanical coupling with the cylinder, thereby, causing increased vibration due to the cylinder stretch mode. Valve life is even shorter than for slow speeds and can be on the order of a few months. The thermal efficiency is 10% to 15% lower than slow-speed equipment with the best performance in the 75% to 80% range. The goal of this advanced reciprocating compression program is to develop the technology for both high speed and low speed compression that will expand unit flexibility, increase thermal efficiency, and increase reliability and integrity

  3. Advanced Natural Gas Reciprocating Engine(s)

    SciTech Connect

    Kwok, Doris; Boucher, Cheryl

    2009-09-30

    Energy independence and fuel savings are hallmarks of the nation’s energy strategy. The advancement of natural gas reciprocating engine power generation technology is critical to the nation’s future. A new engine platform that meets the efficiency, emissions, fuel flexibility, cost and reliability/maintainability targets will enable American manufacturers to have highly competitive products that provide substantial environmental and economic benefits in the US and in international markets. Along with Cummins and Waukesha, Caterpillar participated in a multiyear cooperative agreement with the Department of Energy to create a 50% efficiency natural gas powered reciprocating engine system with a 95% reduction in NOx emissions by the year 2013. This platform developed under this agreement will be a significant contributor to the US energy strategy and will enable gas engine technology to remain a highly competitive choice, meeting customer cost of electricity targets, and regulatory environmental standard. Engine development under the Advanced Reciprocating Engine System (ARES) program was divided into phases, with the ultimate goal being approached in a series of incremental steps. This incremental approach would promote the commercialization of ARES technologies as soon as they emerged from development and would provide a technical and commercial foundation of later-developing technologies. Demonstrations of the Phase I and Phase II technology were completed in 2004 and 2008, respectively. Program tasks in Phase III included component and system development and testing from 2009-2012. Two advanced ignition technology evaluations were investigated under the ARES program: laser ignition and distributed ignition (DIGN). In collaboration with Colorado State University (CSU), a laser ignition system was developed to provide ignition at lean burn and high boost conditions. Much work has been performed in Caterpillar’s DIGN program under the ARES program. This work

  4. Energy expenditure and fatiguability in paraplegic ambulation using reciprocating gait orthosis and electric stimulation.

    PubMed

    Hirokawa, S; Solomonow, M; Baratta, R; D'Ambrosia, R

    1996-03-01

    To clarify the relationship between metabolic energy expenditure and fatiguability in paraplegic persons fitted with orthoses, we measured energy consumption in six thoracic paraplegic patients ambulating by means of reciprocating gait orthosis (RGO) used with and without functional electrical stimulation (FES). The data obtained from persons using both RGO and FES were adjusted to allow for the effects of fatiguability so as to obtain an approximate value for upper-body consumption. The data obtained from persons using RGO only were not adjusted, because no energy consumption occurred in the lower portion of the body. The data, expressed in kcal/kg-min and kcal/kg-m, were plotted against walking speed attained using RGO, and RGO with FES. The results were compared with those from persons fitted with long leg braces (LLB), hip guidance orthoses (HGO) and an FES walking aid (data obtained from available literature). We found that the lowest energy expenditure in kcal/kg-m across the full range of walking speeds occurred when both RGO and FES were used together, followed by RGO only, HGO, LLB, and FES only, respectively. The lowest energy expenditure in kcal/kg-min, for walking speeds, below 0-28 m/s, also occurred when both RGO and FES were used together, followed by RGO only, HGO, LLB, and FES only. The results suggest that, although the use of FES with RGO may increase oxygen uptake, it decreases energy expenditure in the upper extremities, thereby reducing patient fatigue. They also suggest that mechanical orthosis giving passive support to the hip, knee and ankle in combination with FES may provide the most efficient walking aid for paraplegic persons.

  5. Advanced Natural Gas Reciprocating Engine(s)

    SciTech Connect

    Pike, Edward

    2014-03-31

    The objective of the Cummins ARES program, in partnership with the US Department of Energy (DOE), is to develop advanced natural gas engine technologies that increase engine system efficiency at lower emissions levels while attaining lower cost of ownership. The goals of the project are to demonstrate engine system achieving 50% Brake Thermal Efficiency (BTE) in three phases, 44%, 47% and 50% (starting baseline efficiency at 36% BTE) and 0.1 g/bhp-hr NOx system out emissions (starting baseline NOx emissions at 2 – 4 g/bhp-hr NOx). Primary path towards above goals include high Brake Mean Effective Pressure (BMEP), improved closed cycle efficiency, increased air handling efficiency and optimized engine subsystems. Cummins has successfully demonstrated each of the phases of this program. All targets have been achieved through application of a combined set of advanced base engine technologies and Waste Heat Recovery from Charge Air and Exhaust streams, optimized and validated on the demonstration engine and other large engines. The following architectures were selected for each Phase: Phase 1: Lean Burn Spark Ignited (SI) Key Technologies: High Efficiency Turbocharging, Higher Efficiency Combustion System. In production on the 60/91L engines. Over 500MW of ARES Phase 1 technology has been sold. Phase 2: Lean Burn Technology with Exhaust Waste Heat Recovery (WHR) System Key Technologies: Advanced Ignition System, Combustion Improvement, Integrated Waste Heat Recovery System. Base engine technologies intended for production within 2 to 3 years Phase 3: Lean Burn Technology with Exhaust and Charge Air Waste Heat Recovery System Key Technologies: Lower Friction, New Cylinder Head Designs, Improved Integrated Waste Heat Recovery System. Intended for production within 5 to 6 years Cummins is committed to the launch of next generation of large advanced NG engines based on ARES technology to be commercialized worldwide.

  6. Differences in gait velocity and trunk acceleration during semicircular turning gait with and without bag in females of very advanced age.

    PubMed

    Shin, Sun-Shil; Yoo, Won-Gyu

    2016-08-01

    [Purpose] Gait velocity and trunk acceleration during semicircular turning gait with and without carrying a hand-held bag were compared in females of very advanced age. [Subjects and Methods] Ten female volunteers of very advanced age who could walk independently were recruited for this study. Gait velocity and trunk acceleration were measured using an accelerometer during semicircular turning gait with and without carrying a hand-held bag. [Results] Gait velocity during semicircular turning gait was greater with the bag than without the bag. [Conclusions] Trunk stability during semicircular turning gait was higher when the subjects carried a bag. Additional arm load could be considered during gait training in females of very advanced age. PMID:27630425

  7. Differences in gait velocity and trunk acceleration during semicircular turning gait with and without bag in females of very advanced age

    PubMed Central

    Shin, Sun-Shil; Yoo, Won-Gyu

    2016-01-01

    [Purpose] Gait velocity and trunk acceleration during semicircular turning gait with and without carrying a hand-held bag were compared in females of very advanced age. [Subjects and Methods] Ten female volunteers of very advanced age who could walk independently were recruited for this study. Gait velocity and trunk acceleration were measured using an accelerometer during semicircular turning gait with and without carrying a hand-held bag. [Results] Gait velocity during semicircular turning gait was greater with the bag than without the bag. [Conclusions] Trunk stability during semicircular turning gait was higher when the subjects carried a bag. Additional arm load could be considered during gait training in females of very advanced age. PMID:27630425

  8. Differences in gait velocity and trunk acceleration during semicircular turning gait with and without bag in females of very advanced age

    PubMed Central

    Shin, Sun-Shil; Yoo, Won-Gyu

    2016-01-01

    [Purpose] Gait velocity and trunk acceleration during semicircular turning gait with and without carrying a hand-held bag were compared in females of very advanced age. [Subjects and Methods] Ten female volunteers of very advanced age who could walk independently were recruited for this study. Gait velocity and trunk acceleration were measured using an accelerometer during semicircular turning gait with and without carrying a hand-held bag. [Results] Gait velocity during semicircular turning gait was greater with the bag than without the bag. [Conclusions] Trunk stability during semicircular turning gait was higher when the subjects carried a bag. Additional arm load could be considered during gait training in females of very advanced age.

  9. Technological advances in interventions to enhance poststroke gait.

    PubMed

    Sheffler, Lynne R; Chae, John

    2013-05-01

    Neurologic rehabilitation interventions may be either therapeutic or compensatory. Included in this article are lower extremity functional electrical stimulation, body weight-supported treadmill training, and lower extremity robotic-assisted gait training. These poststroke gait training therapies are predicated on activity-dependent neuroplasticity. All three interventions have been trialed extensively in research and clinical settings to show a positive effect on various gait parameters and measures of walking performance. This article provides an overview of evidence-based research that supports the efficacy of these three interventions to improve gait, as well as providing perspective on future developments to enhance poststroke gait in neurologic rehabilitation.

  10. Caterpillar`s advanced reciprocating engine for distributed generation markets

    SciTech Connect

    Gerber, G.; Brandes, D.; Reinhart, M.; Nagel, G.; Wong, E.

    1999-11-01

    Competition in energy markets and federal and state policy advocating clean, advanced technologies as means to achieve environmental and global climate change goals are clear drivers to original equipment manufacturers of prime movers. Underpinning competition are the principle of consumer choice to facilitate retail competition, and the desire to improve system and grid reliability. Caterpillar`s Gas Engine Division is responding to the market`s demand for a more efficient, lower lifecycle cost engine with reduced emissions. Cat`s first generation TARGET engine will be positioned to effectively serve distributed generation and combined heat and power (CHP) applications. TARGET (The Advanced Reciprocating Gas Engine Technology) will embody Cat`s product attributes: durability, reliability, and competitively priced life cycle cost products. Further, Caterpillar`s nationwide, fully established dealer sales and service ensure continued product support subsequent to the sale and installation of the product.

  11. Technological Advances in Interventions to Enhance Post-Stroke Gait

    PubMed Central

    Sheffler, Lynne R.; Chae, John

    2012-01-01

    Synopsis This article provides a comprehensive review of specific rehabilitation interventions used to enhance hemiparetic gait following stroke. Neurologic rehabilitation interventions may be either therapeutic resulting in enhanced motor recovery or compensatory whereby assistance or substitution for neurological deficits results in improved functional performance. Included in this review are lower extremity functional electrical stimulation (FES), body-weight supported treadmill training (BWSTT), and lower extremity robotic-assisted gait training. These post-stroke gait training therapies are predicated on activity-dependent neuroplasticity which is the concept that cortical reorganization following central nervous system injury may be induced by repetitive, skilled, and cognitively engaging active movement. All three interventions have been trialed extensively in both research and clinical settings to demonstrate a positive effect on various gait parameters and measures of walking performance. However, more evidence is necessary to determine if specific technology-enhanced gait training methods are superior to conventional gait training methods. This review provides an overview of evidence-based research which supports the efficacy of these three interventions to improve gait, as well as provide perspective on future developments to enhance post-stroke gait in neurologic rehabilitation. PMID:23598265

  12. Proactive gait strategies to mitigate risk of obstacle contact are more prevalent with advancing age.

    PubMed

    Muir, B C; Haddad, J M; Heijnen, M J H; Rietdyk, S

    2015-01-01

    The purposes of this study were to determine if healthy older adults adopt strategies to decrease the likelihood of obstacle contact, and to determine how these strategies are modified as a function of advancing age. Three age groups were examined: 20-25 yo (N = 19), 65-79 yo (N = 11), and 80-91 yo (N = 18). Participants stepped over a stationary, visible obstacle on a walkway. Step length and gait speed progressively decreased with advancing age; the shorter step length resulted in closer foot placement to the obstacle and an associated increased risk of obstacle contact. Lead (first limb to cross the obstacle) and trail (second) limb trajectories were examined for behavior that mitigated the risk of contact. (1) Consistent trail foot placement before the obstacle across all ages allowed space and time for the trail foot to clear the obstacle. (2) To avoid lead limb contact due to closer foot placement before and after the obstacle, the lead toe was raised more vertically after toe-off, and then the foot was extended beyond the landing position (termed lead overshoot) and retracted backwards to achieve the shortened step length. Lead overshoot progressively increased with advancing age. (3) Head angle was progressively lower with advancing age, an apparent attempt to gather more visual information during approach. Overall, a series of proactive strategies were adopted to mitigate risk of contact. However, the larger, more abrupt movements associated with a more vertical foot trajectory and lead overshoot may compromise whole body balance, indicating a possible trade-off between risk of contact and stability.

  13. Advanced Reciprocating Engine Systems (ARES): Raising the Bar on Engine Technology with Increased Efficiency and Reduced Emissions, at Attractive Costs

    SciTech Connect

    2009-02-01

    This is a fact sheet on the U.S. Department of Energy's (DOE) Advanced Reciprocating Engine Systems program (ARES), which is designed to promote separate, but parallel engine development between the major stationary, gaseous fueled engine manufacturers in the United States.

  14. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    SciTech Connect

    Victor W. Wong; Tian Tian; Grant Smedley; Jeffrey Jocsak

    2004-09-30

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston/ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and emissions. An iterative process of simulation, experimentation and analysis, are being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston/ring dynamic and friction models have been developed and applied that illustrated the fundamental relationships between design parameters and friction losses. Various low-friction strategies and ring-design concepts have been explored, and engine experiments have been done on a full-scale Waukesha VGF F18 in-line 6 cylinder power generation engine rated at 370 kW at 1800 rpm. Current accomplishments include designing and testing ring-packs using a subtle top-compression-ring profile (skewed barrel design), lowering the tension of the oil-control ring, employing a negative twist to the scraper ring to control oil consumption. Initial test data indicate that piston ring-pack friction was reduced by 35% by lowering the oil-control ring tension alone, which corresponds to a 1.5% improvement in fuel efficiency. Although small in magnitude, this improvement represents a first step towards anticipated aggregate improvements from other strategies. Other ring-pack design strategies to lower friction have been identified, including reduced axial distance between the top two rings, tilted top-ring groove. Some of these configurations have been tested and some await further evaluation. Colorado State University performed the tests and Waukesha Engine Dresser, Inc. provided technical support. Key elements of the continuing work include optimizing the engine piston design, application of surface and material developments in conjunction with improved lubricant properties, system modeling and analysis, and continued technology

  15. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    SciTech Connect

    Victor W. Wong; Tian Tian; Grant Smedley

    2003-08-28

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston/ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and emissions. A detailed set of piston/ring dynamic and friction models have been developed and applied that illustrated the fundamental relationships between design parameters and friction losses. Various low-friction strategies and concepts have been explored, and engine experiments will validate these concepts. An iterative process of experimentation, simulation and analysis, will be followed with the goal of demonstrating a complete optimized low-friction engine system. As planned, MIT has developed guidelines for an initial set of low-friction piston-ring-pack designs. Current recommendations focus on subtle top-piston-ring and oil-control-ring characteristics. A full-scale Waukesha F18 engine has been installed at Colorado State University and testing of the baseline configuration is in progress. Components for the first design iteration are being procured. Subsequent work includes examining the friction and engine performance data and extending the analyses to other areas to evaluate opportunities for further friction improvement and the impact on oil consumption/emission and wear, towards demonstrating an optimized reduced-friction engine system.

  16. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    SciTech Connect

    Victor Wong; Tian Tian; Luke Moughon; Rosalind Takata; Jeffrey Jocsak

    2006-03-31

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston and piston ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and wear. An iterative process of simulation, experimentation and analysis is being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston and piston-ring dynamic and friction models have been developed and applied that illustrate the fundamental relationships among mechanical, surface/material and lubricant design parameters and friction losses. Demonstration of low-friction ring-pack designs in the Waukesha VGF 18GL engine confirmed total engine FEMP (friction mean effective pressure) reduction of 7-10% from the baseline configuration without significantly increasing oil consumption or blow-by flow. This represents a substantial (30-40%) reduction of the ringpack friction alone. The measured FMEP reductions were in good agreement with the model predictions. Further improvements via piston, lubricant, and surface designs offer additional opportunities. Tests of low-friction lubricants are in progress and preliminary results are very promising. The combined analysis of lubricant and surface design indicates that low-viscosity lubricants can be very effective in reducing friction, subject to component wear for extremely thin oils, which can be mitigated with further lubricant formulation and/or engineered surfaces. Hence a combined approach of lubricant design and appropriate wear reduction offers improved potential for minimum engine friction loss. Piston friction studies indicate that a flatter piston with a more flexible skirt, together with optimizing the waviness and film thickness on the piston skirt offer significant friction reduction. Combined with low-friction ring-pack, material and lubricant parameters, a total power cylinder friction

  17. ATF (Advanced Toroidal Facility) edge plasma turbulence studies using a fast reciprocating Langmuir probe

    SciTech Connect

    Uckan, T.; Hidalgo, C.; Bell, J.D.; Harris, J.H.; Dunlap, J.L.; Dyer, G.R.; Mioduszewski, P.K.; Wilgen, J.B. ); Ritz, C.P.; Wootton, A.J.; Rhodes, T.L.; Carter, K. . Fusion Research Center)

    1990-01-01

    Electrostatic turbulence on the edge of the Advanced Torodial Facility (ATF) torsatron is investigated experimentally with a fast reciprocating Langmuir probe (FRLP) array. Initial measurements of plasma electron density n{sub e} and temperature T{sub e} and fluctuations in density ({tilde n}{sub e}) and plasma floating potential ({tilde {phi}}{sub f}) are made in ECH plasmas at 1 T. At the last closed flux surface (LCFS, r/{bar a} {approximately}1), T{sub e} {approx} 20--40 eV and n{sub e} {approx} 10{sup 12} cm{sup {minus}3} for a line-averaged electron density {bar n}{sub e} = (3--6) {times} 10{sup 12} cm{sup {minus}3}. Relative fluctuation levels, as the FRLP is moved into core plasma where T{sub e} > 20 eV, are {tilde n}{sub e}/n{sub e} {approx} 5%, and e {tilde {phi}}{sub f}/T{sub e} {approx} 2{tilde n}{sub e}/n{sub e} about 2 cm inside the LCFS. The observed fluctuation spectra are broadband (40--300 kHz) with {bar k}{rho}{sub s} {le} 0.1, where {bar k} is the wavenumber of the fluctuations and {rho}{sub s} is the ion Larmor radius at the sound speed. The propagation direction of the fluctuations reverses to the electron diamagnetic direction around r/{bar a} < 1. The phase velocity and the electron drift velocity are comparable (v{sub ph} {approximately} v{sub de}). The fluctuation-induced particle flux is comparable to fluxes estimated from the particle balance using the H{sub {alpha}} spectroscopic measurements. Many of the features seen in these experiments resemble the features of ohmically heated plasmas in the Texas Experimental Tokamak (TEXT). 17 refs., 10 figs.

  18. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    SciTech Connect

    Victor Wong; Tian Tian; Luke Moughon; Rosalind Takata; Jeffrey Jocsak

    2005-09-30

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston and piston ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and wear. An iterative process of simulation, experimentation and analysis is being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston and piston-ring dynamic and friction models have been developed and applied that illustrate the fundamental relationships between design parameters and friction losses. Low friction ring designs have already been recommended in a previous phase, with full-scale engine validation partially completed. Current accomplishments include the addition of several additional power cylinder design areas to the overall system analysis. These include analyses of lubricant and cylinder surface finish and a parametric study of piston design. The Waukesha engine was found to be already well optimized in the areas of lubricant, surface skewness and honing cross-hatch angle, where friction reductions of 12% for lubricant, and 5% for surface characteristics, are projected. For the piston, a friction reduction of up to 50% may be possible by controlling waviness alone, while additional friction reductions are expected when other parameters are optimized. A total power cylinder friction reduction of 30-50% is expected, translating to an engine efficiency increase of two percentage points from its current baseline towards the goal of 50% efficiency. Key elements of the continuing work include further analysis and optimization of the engine piston design, in-engine testing of recommended lubricant and surface designs, design iteration and optimization of previously recommended technologies, and full-engine testing of a complete, optimized, low-friction power cylinder system.

  19. Low-Engine-Friction Technology for Advanced Natural-Gas Reciprocating Engines

    SciTech Connect

    Victor Wong; Tian Tian; G. Smedley; L. Moughon; Rosalind Takata; J. Jocsak

    2006-11-30

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston and piston ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and wear. An iterative process of simulation, experimentation and analysis has been followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. In this program, a detailed set of piston and piston-ring dynamic and friction models have been adapted and applied that illustrate the fundamental relationships among mechanical, surface/material and lubricant design parameters and friction losses. Demonstration of low-friction ring-pack designs in the Waukesha VGF 18GL engine confirmed ring-pack friction reduction of 30-40%, which translates to total engine FEMP (friction mean effective pressure) reduction of 7-10% from the baseline configuration without significantly increasing oil consumption or blow-by flow. The study on surface textures, including roughness characteristics, cross hatch patterns, dimples and grooves have shown that even relatively small-scale changes can have a large effect on ring/liner friction, in some cases reducing FMEP by as much as 30% from a smooth surface case. The measured FMEP reductions were in good agreement with the model predictions. The combined analysis of lubricant and surface design indicates that low-viscosity lubricants can be very effective in reducing friction, subject to component wear for extremely thin oils, which can be mitigated with further lubricant formulation and/or engineered surfaces. Hence a combined approach of lubricant design and appropriate wear reduction offers improved potential for minimum engine friction loss. Testing of low-friction lubricants showed that total engine FMEP reduced by up to {approx}16.5% from the commercial reference oil without significantly increasing oil consumption or blow-by flow. Piston friction studies

  20. Advanced Natural Gas Reciprocating Engine: Parasitic Loss Control through Surface Modification

    SciTech Connect

    Farshid Sadeghi; Chin-Pei Wang

    2008-12-31

    This report presents results of our investigation on parasitic loss control through surface modification in reciprocating engine. In order to achieve the objectives several experimental and corresponding analytical models were designed and developed to corroborate our results. Four different test rigs were designed and developed to simulate the contact between the piston ring and cylinder liner (PRCL) contact. The Reciprocating Piston Test Rig (RPTR) is a novel suspended liner test apparatus which can be used to accurately measure the friction force and side load at the piston-cylinder interface. A mixed lubrication model for the complete ring-pack and piston skirt was developed to correlate with the experimental measurements. Comparisons between the experimental and analytical results showed good agreement. The results revealed that in the reciprocating engines higher friction occur near TDC and BDC of the stroke due to the extremely low piston speed resulting in boundary lubrication. A Small Engine Dynamometer Test Rig was also designed and developed to enable testing of cylinder liner under motored and fired conditions. Results of this study provide a baseline from which to measure the effect of surface modifications. The Pin on Disk Test Rig (POD) was used in a flat-on-flat configuration to study the friction effect of CNC machining circular pockets and laser micro-dimples. The results show that large and shallow circular pockets resulted in significant friction reduction. Deep circular pockets did not provide much load support. The Reciprocating Liner Test Rig (RLTR) was designed to simplifying the contact at the PRCL interface. Accurate measurement of friction was obtained using 3-axis piezoelectric force transducer. Two fiber optic sensors were used to measure the film thickness precisely. The results show that the friction force is reduced through the use of modified surfaces. The Shear Driven Test Rig (SDTR) was designed to simulate the mechanism of the

  1. Advanced Reciprocating Engine Systems (ARES) Research at Argonne National Laboratory. A Report

    SciTech Connect

    Gupta, Sreenath; Biruduganti, Muni; Bihari, Bipin; Sekar, Raj

    2014-08-01

    The goals of these experiments were to determine the potential of employing spectral measurements to deduce combustion metrics such as HRR, combustion temperatures, and equivalence ratios in a natural gas-fired reciprocating engine. A laser-ignited, natural gas-fired single-cylinder research engine was operated at various equivalence ratios between 0.6 and 1.0, while varying the EGR levels between 0% and maximum to thereby ensure steady combustion. Crank angle-resolved spectral signatures were collected over 266-795 nm, encompassing chemiluminescence emissions from OH*, CH*, and predominantly by CO2* species. Further, laser-induced gas breakdown spectra were recorded under various engine operating conditions.

  2. Hemiparetic Gait.

    PubMed

    Sheffler, Lynne R; Chae, John

    2015-11-01

    The most common pattern of walking impairment poststroke is hemiparetic gait, which is characterized by asymmetry associated with an extensor synergy pattern of hip extension and adduction, knee extension, and ankle plantar flexion and inversion. There are characteristic changes in the spatiotemporal, kinematic and kinetic parameters, and dynamic electromyography patterns in hemiparesis, which may be assessed most accurately in a motion studies laboratory. An understanding of normal human gait is necessary to assess the complex interplay of motor, sensory, and proprioceptive loss; spasticity; and/or ataxia on hemiparetic gait. PMID:26522901

  3. Milestones in gait, balance, and falling.

    PubMed

    Nutt, John G; Horak, Fay B; Bloem, Bastiaan R

    2011-05-01

    Gait, balance, and falls have become increasingly common topics of published articles in the Movement Disorders journal since its launch in 1986. This growth represents an increasing awareness of the importance of mobility to patients' quality of life. New methods have become available that allow for accurate measurement of many aspects for gait and balance. This has led to new concepts of understanding gait and balance disorders. Neuroimaging has begun to reveal the neural circuitry underlying gait and balance. The physiology and pathophysiology of balance and gait are beginning to tease out the many processes involved in mobility and how they may be disrupted by disease processes. With these advances, the old therapeutic nihilism that characterized the clinician's approach to falls and gait disorders is disappearing, as innovative physiotherapy, exercise, drugs, and deep brain stimulation are being employed for gait and balance disorders. PMID:21626560

  4. System of reporting and comparing influence of ambulatory aids on gait.

    PubMed

    Smidt, G L; Mommens, M A

    1980-05-01

    The purposes of this study were to 1) present a standardized approach for describing gait when assistive devices are used, 2) report reference data for unassisted and assisted gait patterns for normal adults, and 3) discuss clinical implications for selected variables of gait. Using an automated gait system, measurements for temporal and distance factors and accelerometry were obtained for 25 normal young adults. In addition to the formulation of a new system for describing gait patterns when assistive devices are used, the results of the study were that 1) subjects walked slower with ambulatory aids than without them, 2) assisted gaits with the same number of counts per cycle tended to have similar measurements, 3) reciprocal swing times and stance times were symmetrical for all types of gait studied, 4) double stance times and step times were asymmetrical for three types of assisted gait, and 5) vertical accelerations were disproportionately elevated for most assisted gaits.

  5. Electromagnetic Reciprocity.

    SciTech Connect

    Aldridge, David F.

    2014-11-01

    A reciprocity theorem is an explicit mathematical relationship between two different wavefields that can exist within the same space - time configuration. Reciprocity theorems provi de the theoretical underpinning for mod ern full waveform inversion solutions, and also suggest practical strategies for speed ing up large - scale numerical modeling of geophysical datasets . In the present work, several previously - developed electromagnetic r eciprocity theorems are generalized to accommodate a broader range of medi um, source , and receiver types. Reciprocity relations enabling the interchange of various types of point sources and point receivers within a three - dimensional electromagnetic model are derived. Two numerical modeling algorithms in current use are successfully tested for adherence to reciprocity. Finally, the reciprocity theorem forms the point of departure for a lengthy derivation of electromagnetic Frechet derivatives. These mathe matical objects quantify the sensitivity of geophysical electromagnetic data to variatio ns in medium parameters, and thus constitute indispensable tools for solution of the full waveform inverse problem. ACKNOWLEDGEMENTS Sandia National Labor atories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. Signif icant portions of the work reported herein were conducted under a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories (SNL) and CARBO Ceramics Incorporated. The author acknowledges Mr. Chad Cannan and Mr. Terry Pa lisch of CARBO Ceramics, and Ms. Amy Halloran, manager of SNL's Geophysics and Atmospheric Sciences Department, for their interest in and encouragement of this work. Special thanks are due to Dr . Lewis C. Bartel ( recently retired from Sandia National Labo ratories and now a

  6. Acoustic Gaits: Gait Analysis With Footstep Sounds.

    PubMed

    Altaf, M Umair Bin; Butko, Taras; Juang, Biing-Hwang Fred

    2015-08-01

    We describe the acoustic gaits-the natural human gait quantitative characteristics derived from the sound of footsteps as the person walks normally. We introduce the acoustic gait profile, which is obtained from temporal signal analysis of sound of footsteps collected by microphones and illustrate some of the spatio-temporal gait parameters that can be extracted from the acoustic gait profile by using three temporal signal analysis methods-the squared energy estimate, Hilbert transform and Teager-Kaiser energy operator. Based on the statistical analysis of the parameter estimates, we show that the spatio-temporal parameters and gait characteristics obtained using the acoustic gait profile can consistently and reliably estimate a subset of clinical and biometric gait parameters currently in use for standardized gait assessments. We conclude that the Teager-Kaiser energy operator provides the most consistent gait parameter estimates showing the least variation across different sessions and zones. Acoustic gaits use an inexpensive set of microphones with a computing device as an accurate and unintrusive gait analysis system. This is in contrast to the expensive and intrusive systems currently used in laboratory gait analysis such as the force plates, pressure mats and wearable sensors, some of which may change the gait parameters that are being measured.

  7. Reciprocal translocations

    SciTech Connect

    1993-12-31

    Chapter 26, describes reciprocal translocations of chromosomes: their occurrence, breakpoints, and multiple rearrangements. In addition, phenotypes of balanced and unbalanced translocation carriers and fetal death are discussed. Examples of translocation families are given. Meiosis and genetic risk in translocation carriers is presented. Finally, sperm chromosomes in meiotic segregation analysis is mentioned. 39 refs., 3 figs., 1 tab.

  8. Integrated Combined Heat and Power/Advanced Reciprocating Internal Combustion Engine System for Landfill Gas to Power Applications

    SciTech Connect

    2009-02-01

    Gas Technology Institute will collaborate with Integrated CHP Systems Corporation, West Virginia University, Vronay Engineering Services, KAR Engineering Associates, Pioneer Air Systems, and Energy Concepts Company to recover waste heat from reciprocating engines. The project will integrate waste heat recovery along with gas clean-up technology system improvements. This will address fuel quality issues that have hampered expanded use of opportunity fuels such as landfill gas, digester biogas, and coal mine methane. This will enable increased application of CHP using renewable and domestically derived opportunity fuels.

  9. Diabetic Foot Biomechanics and Gait Dysfunction

    PubMed Central

    Wrobel, James S.; Najafi, Bijan

    2010-01-01

    Background Diabetic foot complications represent significant morbidity and precede most of the lower extremity amputations performed. Peripheral neuropathy is a frequent complication of diabetes shown to affect gait. Glycosylation of soft tissues can also affect gait. The purpose of this review article is to highlight the changes in gait for persons with diabetes and highlight the effects of glycosylation on soft tissues at the foot–ground interface. Methods PubMed, the Cochrane Library, and EBSCOhost® on-line databases were searched for articles pertaining to diabetes and gait. Bibliographies from relevant manuscripts were also searched. Findings Patients with diabetes frequently exhibit a conservative gait strategy where there is slower walking speed, wider base of gait, and prolonged double support time. Glycosylation affects are observed in the lower extremities. Initially, skin thickness decreases and skin hardness increases; tendons thicken; muscles atrophy and exhibit activation delays; bones become less dense; joints have limited mobility; and fat pads are less thick, demonstrate fibrotic atrophy, migrate distally, and may be stiffer. Interpretation In conclusion, there do appear to be gait changes in patients with diabetes. These changes, coupled with local soft tissue changes from advanced glycosylated end products, also alter a patient’s gait, putting them at risk of foot ulceration. Better elucidation of these changes throughout the entire spectrum of diabetes disease can help design better treatments and potentially reduce the unnecessarily high prevalence of foot ulcers and amputation. PMID:20663446

  10. Therapeutic effect of functional electrical stimulation-triggered gait training corresponding gait cycle for stroke.

    PubMed

    Chung, Yijung; Kim, Jung-Hyun; Cha, Yuri; Hwang, Sujin

    2014-07-01

    The purpose of this study was to determine the therapeutic effects of functional electrical stimulation (FES) applied to the gluteus medius and tibialis anterior muscles during the gait cycle in individuals with hemiparetic stroke. Eighteen patients who had suffered a stroke were enrolled in this study. The participants were divided into either the gluteus medius and tibialis anterior (GM + TA) training group (n = 9) or the control group (n = 9). The GM + TA group received FES-triggered gait training to the gluteus medius (GM) in the stance phase and the tibialis anterior (TA) in the swing phase for 30 min, 5 session a week over a 6-week period, and control group who received only gait training without FES-triggered for the same duration of time. A foot-switch sensor was used to trigger the device in the stance (GM) and swing (TA) phases of the gait cycle reciprocally. This study measured three types of outcome measures, including spatiotemporal gait parameters, muscles activities, and balance function. After 6 weeks training, there was a significant improvement in gait velocity, cadence, stride length, and gait symmetry in the GM + TA training group compared to the control group. Dynamic balance function was significantly improved in the GM + TA training group compared to the control group. The mean changeable values of the GM was significantly greater strength in the GM + TA training group than the control group. These findings suggest that FES-triggered gait training of the GM in the stance phase and TA in the swing phase may improve the spatiotemporal parameters of gait in persons with hemiparetic stroke.

  11. Gait quality assessment using self-organising artificial neural networks.

    PubMed

    Barton, Gabor; Lisboa, Paulo; Lees, Adrian; Attfield, Steve

    2007-03-01

    In this study, the challenge to maximise the potential of gait analysis by employing advanced methods was addressed by using self-organising neural networks to quantify the deviation of patients' gait from normal. Data including three-dimensional joint angles, moments and powers of the two lower limbs and the pelvis were used to train Kohonen artificial neural networks to learn an abstract definition of normal gait. Subsequently, data from patients with gait problems were presented to the network which quantified the quality of gait in the form of a single curve by calculating the quantisation error during the gait cycle. A sensitivity analysis involving the manipulation of gait variables' weighting was able to highlight specific causes of the deviation including the anatomical location and the timing of wrong gait patterns. Use of the quantisation error can be regarded as an extension of previously described gait indices because it measures the goodness of gait and additionally provides information related to the causes underlying gait deviations.

  12. β-reciprocal polynomials

    NASA Astrophysics Data System (ADS)

    Withers, Christopher S.; Nadarajah, Saralees

    2016-07-01

    A new class of polynomials pn(x) known as β-reciprocal polynomials is defined. Given a parameter ? that is not a root of -1, we show that the only β-reciprocal polynomials are pn(x) ≡ xn. When β is a root of -1, other polynomials are possible. For example, the Hermite polynomials are i-reciprocal, ?.

  13. Reciprocating pellet press

    DOEpatents

    Jones, Charles W.

    1981-04-07

    A machine for pressing loose powder into pellets using a series of reciprocating motions has an interchangeable punch and die as its only accurately machines parts. The machine reciprocates horizontally between powder receiving and pressing positions. It reciprocates vertically to press, strip and release a pellet.

  14. Animal Gaits and Symmetry

    NASA Astrophysics Data System (ADS)

    Golubitsky, Martin

    2012-04-01

    Many gaits of four-legged animals are described by symmetry. For example, when a horse paces it moves both left legs in unison and then both right legs and so on. The motion is described by two symmetries: Interchange front and back legs, and swap left and right legs with a half-period phase shift. Biologists postulate the existence of a central pattern generator (CPG) in the neuronal system that sends periodic signals to the legs. CPGs can be thought of as electrical circuits that produce periodic signals and can be modeled by systems with symmetry. In this lecture we discuss animal gaits; use gait symmetries to construct a simplest CPG architecture that naturally produces quadrupedal gait rhythms; and make several testable predictions about gaits.

  15. Recognition using gait.

    SciTech Connect

    Koch, Mark William

    2007-09-01

    Gait or an individual's manner of walking, is one approach for recognizing people at a distance. Studies in psychophysics and medicine indicate that humans can recognize people by their gait and have found twenty-four different components to gait that taken together make it a unique signature. Besides not requiring close sensor contact, gait also does not necessarily require a cooperative subject. Using video data of people walking in different scenarios and environmental conditions we develop and test an algorithm that uses shape and motion to identify people from their gait. The algorithm uses dynamic time warping to match stored templates against an unknown sequence of silhouettes extracted from a person walking. While results under similar constraints and conditions are very good, the algorithm quickly degrades with varying conditions such as surface and clothing.

  16. Reciprocity in directed networks

    NASA Astrophysics Data System (ADS)

    Yin, Mei; Zhu, Lingjiong

    2016-04-01

    Reciprocity is an important characteristic of directed networks and has been widely used in the modeling of World Wide Web, email, social, and other complex networks. In this paper, we take a statistical physics point of view and study the limiting entropy and free energy densities from the microcanonical ensemble, the canonical ensemble, and the grand canonical ensemble whose sufficient statistics are given by edge and reciprocal densities. The sparse case is also studied for the grand canonical ensemble. Extensions to more general reciprocal models including reciprocal triangle and star densities will likewise be discussed.

  17. A Grassmann graph embedding framework for gait analysis

    NASA Astrophysics Data System (ADS)

    Connie, Tee; Goh, Michael Kah Ong; Teoh, Andrew Beng Jin

    2014-12-01

    Gait recognition is important in a wide range of monitoring and surveillance applications. Gait information has often been used as evidence when other biometrics is indiscernible in the surveillance footage. Building on recent advances of the subspace-based approaches, we consider the problem of gait recognition on the Grassmann manifold. We show that by embedding the manifold into reproducing kernel Hilbert space and applying the mechanics of graph embedding on such manifold, significant performance improvement can be obtained. In this work, the gait recognition problem is studied in a unified way applicable for both supervised and unsupervised configurations. Sparse representation is further incorporated in the learning mechanism to adaptively harness the local structure of the data. Experiments demonstrate that the proposed method can tolerate variations in appearance for gait identification effectively.

  18. Symmetrical gait descriptions

    NASA Astrophysics Data System (ADS)

    Dunajewski, Adam; Dusza, Jacek J.; Rosado Muñoz, Alfredo

    2014-11-01

    The article presents a proposal for the description of human gait as a periodic and symmetric process. Firstly, the data for researches was obtained in the Laboratory of Group SATI in the School of Engineering of University of Valencia. Then, the periodical model - Mean Double Step (MDS) was made. Finally, on the basis of MDS, the symmetrical models - Left Mean Double Step and Right Mean Double Step (LMDS and RMDS) could be created. The method of various functional extensions was used. Symmetrical gait models can be used to calculate the coefficients of asymmetry at any time or phase of the gait. In this way it is possible to create asymmetry, function which better describes human gait dysfunction. The paper also describes an algorithm for calculating symmetric models, and shows exemplary results based on the experimental data.

  19. Gait analysis using wearable sensors.

    PubMed

    Tao, Weijun; Liu, Tao; Zheng, Rencheng; Feng, Hutian

    2012-01-01

    Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications.

  20. Gait Analysis Using Wearable Sensors

    PubMed Central

    Tao, Weijun; Liu, Tao; Zheng, Rencheng; Feng, Hutian

    2012-01-01

    Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications. PMID:22438763

  1. Inertial Sensor-Based Gait Recognition: A Review.

    PubMed

    Sprager, Sebastijan; Juric, Matjaz B

    2015-01-01

    With the recent development of microelectromechanical systems (MEMS), inertial sensors have become widely used in the research of wearable gait analysis due to several factors, such as being easy-to-use and low-cost. Considering the fact that each individual has a unique way of walking, inertial sensors can be applied to the problem of gait recognition where assessed gait can be interpreted as a biometric trait. Thus, inertial sensor-based gait recognition has a great potential to play an important role in many security-related applications. Since inertial sensors are included in smart devices that are nowadays present at every step, inertial sensor-based gait recognition has become very attractive and emerging field of research that has provided many interesting discoveries recently. This paper provides a thorough and systematic review of current state-of-the-art in this field of research. Review procedure has revealed that the latest advanced inertial sensor-based gait recognition approaches are able to sufficiently recognise the users when relying on inertial data obtained during gait by single commercially available smart device in controlled circumstances, including fixed placement and small variations in gait. Furthermore, these approaches have also revealed considerable breakthrough by realistic use in uncontrolled circumstances, showing great potential for their further development and wide applicability. PMID:26340634

  2. Inertial Sensor-Based Gait Recognition: A Review

    PubMed Central

    Sprager, Sebastijan; Juric, Matjaz B.

    2015-01-01

    With the recent development of microelectromechanical systems (MEMS), inertial sensors have become widely used in the research of wearable gait analysis due to several factors, such as being easy-to-use and low-cost. Considering the fact that each individual has a unique way of walking, inertial sensors can be applied to the problem of gait recognition where assessed gait can be interpreted as a biometric trait. Thus, inertial sensor-based gait recognition has a great potential to play an important role in many security-related applications. Since inertial sensors are included in smart devices that are nowadays present at every step, inertial sensor-based gait recognition has become very attractive and emerging field of research that has provided many interesting discoveries recently. This paper provides a thorough and systematic review of current state-of-the-art in this field of research. Review procedure has revealed that the latest advanced inertial sensor-based gait recognition approaches are able to sufficiently recognise the users when relying on inertial data obtained during gait by single commercially available smart device in controlled circumstances, including fixed placement and small variations in gait. Furthermore, these approaches have also revealed considerable breakthrough by realistic use in uncontrolled circumstances, showing great potential for their further development and wide applicability. PMID:26340634

  3. Reciprocating Linear Electric Motor

    NASA Technical Reports Server (NTRS)

    Goldowsky, M. P.

    1984-01-01

    Features include structural simplicity and good force/displacement characteristics. Reciprocating motor has simple, rugged construction, relatively low reciprocating weight, improved power delivery, and improved force control. Wear reduced by use of magnetic bearings. Intended to provide drivers for long-lived Stirling-cycle cryogenic refrigerators, concept has less exotic applications, such as fuel pumps.

  4. The Structure of Reciprocity

    ERIC Educational Resources Information Center

    Molm, Linda D.

    2010-01-01

    Reciprocity is one of the defining features of social exchange and social life, yet exchange theorists have tended to take it for granted. Drawing on work from a decade-long theoretical research program, I argue that reciprocity is structured and variable across different forms of exchange, that these variations in the structure of reciprocity…

  5. Reciprocity and uncertainty.

    PubMed

    Bereby-Meyer, Yoella

    2012-02-01

    Guala points to a discrepancy between strong negative reciprocity observed in the lab and the way cooperation is sustained "in the wild." This commentary suggests that in lab experiments, strong negative reciprocity is limited when uncertainty exists regarding the players' actions and the intentions. Thus, costly punishment is indeed a limited mechanism for sustaining cooperation in an uncertain environment.

  6. The Value of Reciprocity

    ERIC Educational Resources Information Center

    Molm, Linda D.; Schaefer, David R.; Collett, Jessica L.

    2007-01-01

    The value of reciprocity in social exchange potentially comprises both instrumental value (the value of the actual benefits received from exchange) and communicative or symbolic value (the expressive and uncertainty reduction value conveyed by features of the act of reciprocity itself). While all forms of exchange provide instrumental value, we…

  7. Reciprocal NUT spacetimes

    NASA Astrophysics Data System (ADS)

    Momeni, Davood; Chattopadhyay, Surajit; Myrzakulov, Ratbay

    2015-05-01

    In this paper, we study the Ehlers' transformation (sometimes called gravitational duality rotation) for reciprocal static metrics. First, we introduce the concept of reciprocal metric. We prove a theorem which shows how we can construct a certain new static solution of Einstein field equations using a seed metric. Later, we investigate the family of stationary spacetimes of such reciprocal metrics. The key here is a theorem from Ehlers', which relates any static vacuum solution to a unique stationary metric. The stationary metric has a magnetic charge. The spacetime represents Newman-Unti-Tamburino (NUT) solutions. Since any stationary spacetime can be decomposed into a 1 + 3 time-space decomposition, Einstein field equations for any stationary spacetime can be written in the form of Maxwell's equations for gravitoelectromagnetic fields. Further, we show that this set of equations is invariant under reciprocal transformations. An additional point is that the NUT charge changes the sign. As an instructive example, by starting from the reciprocal Schwarzschild as a spherically symmetric solution and reciprocal Morgan-Morgan disk model as seed metrics we find their corresponding stationary spacetimes. Starting from any static seed metric, performing the reciprocal transformation and by applying an additional Ehlers' transformation we obtain a family of NUT spaces with negative NUT factor (reciprocal NUT factors).

  8. Reciprocity and uncertainty.

    PubMed

    Bereby-Meyer, Yoella

    2012-02-01

    Guala points to a discrepancy between strong negative reciprocity observed in the lab and the way cooperation is sustained "in the wild." This commentary suggests that in lab experiments, strong negative reciprocity is limited when uncertainty exists regarding the players' actions and the intentions. Thus, costly punishment is indeed a limited mechanism for sustaining cooperation in an uncertain environment. PMID:22289307

  9. Gait analysis: clinical facts.

    PubMed

    Baker, Richard; Esquenazi, Alberto; Benedetti, Maria G; Desloovere, Kaat

    2016-08-01

    Gait analysis is a well-established tool for the quantitative assessment of gait disturbances providing functional diagnosis, assessment for treatment planning, and monitoring of disease progress. There is a large volume of literature on the research use of gait analysis, but evidence on its clinical routine use supports a favorable cost-benefit ratio in a limited number of conditions. Initially gait analysis was introduced to clinical practice to improve the management of children with cerebral palsy. However, there is good evidence to extend its use to patients with various upper motor neuron diseases, and to lower limb amputation. Thereby, the methodology for properly conducting and interpreting the exam is of paramount relevance. Appropriateness of gait analysis prescription and reliability of data obtained are required in the clinical environment. This paper provides an overview on guidelines for managing a clinical gait analysis service and on the principal clinical domains of its application: cerebral palsy, stroke, traumatic brain injury and lower limb amputation. PMID:27618499

  10. Gait and its assessment in psychiatry

    PubMed Central

    Sanders, Richard D.

    2010-01-01

    Gait reflects all levels of nervous system function. In psychiatry, gait disturbances reflecting cortical and subcortical dysfunction are often seen. Observing spontaneous gait, sometimes augmented by a few brief tests, can be highly informative. The authors briefly review the neuroanatomy of gait, review gait abnormalities seen in psychiatric and neurologic disorders, and describe the assessment of gait. PMID:20805918

  11. Exercises to Improve Gait Abnormalities

    MedlinePlus

    ... Home About iChip Articles Directories Videos Resources Contact Exercises to Improve Gait Abnormalities Home » Article Categories » Exercise and Fitness Font Size: A A A A Exercises to Improve Gait Abnormalities Next Page The manner ...

  12. 32 CFR 148.1 - Intergency reciprocal acceptance .

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... reciprocal acceptance of security policies and procedures for approving, accrediting, and maintaining the... AND CIVILIAN NATIONAL POLICY AND IMPLEMENTATION OF RECIPROCITY OF FACILITIES National Policy on... security systems, preserve vitality of the U.S. industrial base, and advance national security objectives....

  13. 32 CFR 148.1 - Interagency reciprocal acceptance .

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... reciprocal acceptance of security policies and procedures for approving, accrediting, and maintaining the..., MILITARY AND CIVILIAN NATIONAL POLICY AND IMPLEMENTATION OF RECIPROCITY OF FACILITIES National Policy on... security systems, preserve vitality of the U.S. industrial base, and advance national security objectives....

  14. 32 CFR 148.1 - Interagency reciprocal acceptance .

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... reciprocal acceptance of security policies and procedures for approving, accrediting, and maintaining the..., MILITARY AND CIVILIAN NATIONAL POLICY AND IMPLEMENTATION OF RECIPROCITY OF FACILITIES National Policy on... security systems, preserve vitality of the U.S. industrial base, and advance national security objectives....

  15. 32 CFR 148.1 - Interagency reciprocal acceptance .

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... reciprocal acceptance of security policies and procedures for approving, accrediting, and maintaining the..., MILITARY AND CIVILIAN NATIONAL POLICY AND IMPLEMENTATION OF RECIPROCITY OF FACILITIES National Policy on... security systems, preserve vitality of the U.S. industrial base, and advance national security objectives....

  16. Hidden patterns of reciprocity.

    PubMed

    Syi

    2014-03-21

    Reciprocity can help the evolution of cooperation. To model both types of reciprocity, we need the concept of strategy. In the case of direct reciprocity there are four second-order action rules (Simple Tit-for-tat, Contrite Tit-for-tat, Pavlov, and Grim Trigger), which are able to promote cooperation. In the case of indirect reciprocity the key component of cooperation is the assessment rule. There are, again, four elementary second-order assessment rules (Image Scoring, Simple Standing, Stern Judging, and Shunning). The eight concepts can be formalized in an ontologically thin way we need only an action predicate and a value function, two agent concepts, and the constant of goodness. The formalism helps us to discover that the action and assessment rules can be paired, and that they show the same patterns. The logic of these patterns can be interpreted with the concept of punishment that has an inherent paradoxical nature.

  17. Hidden patterns of reciprocity.

    PubMed

    Syi

    2014-03-21

    Reciprocity can help the evolution of cooperation. To model both types of reciprocity, we need the concept of strategy. In the case of direct reciprocity there are four second-order action rules (Simple Tit-for-tat, Contrite Tit-for-tat, Pavlov, and Grim Trigger), which are able to promote cooperation. In the case of indirect reciprocity the key component of cooperation is the assessment rule. There are, again, four elementary second-order assessment rules (Image Scoring, Simple Standing, Stern Judging, and Shunning). The eight concepts can be formalized in an ontologically thin way we need only an action predicate and a value function, two agent concepts, and the constant of goodness. The formalism helps us to discover that the action and assessment rules can be paired, and that they show the same patterns. The logic of these patterns can be interpreted with the concept of punishment that has an inherent paradoxical nature. PMID:24368125

  18. Context based gait recognition

    NASA Astrophysics Data System (ADS)

    Bazazian, Shermin; Gavrilova, Marina

    2012-06-01

    Gait recognition has recently become a popular topic in the field of biometrics. However, the main hurdle is the insufficient recognition rate in the presence of low quality samples. The main focus of this paper is to investigate how the performance of a gait recognition system can be improved using additional information about behavioral patterns of users and the context in which samples have been taken. The obtained results show combining the context information with biometric data improves the performance of the system at a very low cost. The amount of improvement depends on the distinctiveness of the behavioral patterns and the quality of the gait samples. Using the appropriate distinctive behavioral models it is possible to achieve a 100% recognition rate.

  19. Low-resolution gait recognition.

    PubMed

    Zhang, Junping; Pu, Jian; Chen, Changyou; Fleischer, Rudolf

    2010-08-01

    Unlike other biometric authentication methods, gait recognition is noninvasive and effective from a distance. However, the performance of gait recognition will suffer in the low-resolution (LR) case. Furthermore, when gait sequences are projected onto a nonoptimal low-dimensional subspace to reduce the data complexity, the performance of gait recognition will also decline. To deal with these two issues, we propose a new algorithm called superresolution with manifold sampling and backprojection (SRMS), which learns the high-resolution (HR) counterparts of LR test images from a collection of HR/LR training gait image patch pairs. Then, we incorporate SRMS into a new algorithm called multilinear tensor-based learning without tuning parameters (MTP) for LR gait recognition. Our contributions include the following: 1) With manifold sampling, the redundancy of gait image patches is remarkably decreased; thus, the superresolution procedure is more efficient and reasonable. 2) Backprojection guarantees that the learned HR gait images and the corresponding LR gait images can be more consistent. 3) The optimal subspace dimension for dimension reduction is automatically determined without introducing extra parameters. 4) Theoretical analysis of the algorithm shows that MTP converges. Experiments on the USF human gait database and the CASIA gait database show the increased efficiency of the proposed algorithm, compared with previous algorithms. PMID:20199936

  20. Evolution of cooperation by generalized reciprocity

    PubMed Central

    Pfeiffer, Thomas; Rutte, Claudia; Killingback, Timothy; Taborsky, Michael; Bonhoeffer, Sebastian

    2005-01-01

    The evolution of cooperation by direct reciprocity requires that individuals recognize their present partner and remember the outcome of their last encounter with that specific partner. Direct reciprocity thus requires advanced cognitive abilities. Here, we demonstrate that if individuals repeatedly interact within small groups with different partners in a two person Prisoner's Dilemma, cooperation can emerge and also be maintained in the absence of such cognitive capabilities. It is sufficient for an individual to base their decision of whether or not to cooperate on the outcome of their last encounter—even if it was with a different partner. PMID:16024372

  1. Reciprocating piston engine

    SciTech Connect

    Eickmann, K.

    1986-01-07

    This patent describes a reciprocating combustion engine consisting of a cylinder, a piston reciprocating in the cylinder, a top for closing one end of the cylinder, inlets and outlets extending to and from the cylinder for the intake of combustible gas and the expelling of burned exhaust gases. The engine also consists of a device for ignition of the combustible gas, a means of cooling the cylinder and top, a turbine of a turbocharger connected to the outlet, and a compressor of the turbocharger connected to the inlet.

  2. Gait transition cost in humans.

    PubMed

    Usherwood, James R; Bertram, John E A

    2003-11-01

    The energetics of locomotion depend largely on speed, gait and body size. Gait selection for a given speed appears partly, but perhaps not wholly, related to metabolic cost. One cost normally omitted from considerations of locomotion efficiency is the metabolic cost of the transition between gaits. We present the first direct assessment of the metabolic cost for the walk-run/run-walk transition in humans. The average increase in metabolic cost for a step involving a transition is 1.75 times that of a mean non-transition step at a speed where metabolic power requirements are identical for walking and running. Despite this substantial increase in cost for the transition step, the metabolic cost of gait transition is unlikely to have a strong bearing on the process of gait selection as the cost of using a metabolically inappropriate gait, even for only a few steps, will dominate. PMID:14564525

  3. Series of Reciprocal Triangular Numbers

    ERIC Educational Resources Information Center

    Bruckman, Paul; Dence, Joseph B.; Dence, Thomas P.; Young, Justin

    2013-01-01

    Reciprocal triangular numbers have appeared in series since the very first infinite series were summed. Here we attack a number of subseries of the reciprocal triangular numbers by methodically expressing them as integrals.

  4. Reciprocal Predicates in Japanese.

    ERIC Educational Resources Information Center

    Ishii, Yasuo

    A study of reciprocals in Japanese compares two kinds: (1) a verbal suffix "aw"; and (2) an NP argument "otagai." Although "otagai" appears to be taken care of by syntactic binding theory, it is proposed that there is no evidence for the existence of a syntactic position of the object NP in the case of "aw." The suffix can be characterized as…

  5. Gait and balance disorders.

    PubMed

    Masdeu, Joseph C

    2016-01-01

    This chapter focuses on one of the most common types of neurologic disorders: altered walking. Walking impairment often reflects disease of the neurologic structures mediating gait, balance or, most often, both. These structures are distributed along the neuraxis. For this reason, this chapter is introduced by a brief description of the neurobiologic underpinning of walking, stressing information that is critical for imaging, namely, the anatomic representation of gait and balance mechanisms. This background is essential not only in order to direct the relevant imaging tools to the regions more likely to be affected but also to interpret correctly imaging findings that may not be related to the walking deficit object of clinical study. The chapter closes with a discussion on how to image some of the most frequent etiologies causing gait or balance impairment. However, it focuses on syndromes not already discussed in other chapters of this volume, such as Parkinson's disease and other movement disorders, already discussed in Chapter 48, or cerebellar ataxia, in Chapter 23, in the previous volume. As regards vascular disease, the spastic hemiplegia most characteristic of brain disease needs little discussion, while the less well-understood effects of microvascular disease are extensively reviewed here, together with the imaging approach. PMID:27430451

  6. Temporal and spatial organization of gait-related electrocortical potentials.

    PubMed

    Knaepen, Kristel; Mierau, Andreas; Tellez, Helio Fernandez; Lefeber, Dirk; Meeusen, Romain

    2015-07-10

    To advance gait rehabilitation research it is of great importance to understand the supraspinal control of walking. In this study, the temporal and spatial characteristics of averaged electrocortical activity during treadmill walking in healthy subjects was assessed. Electroencephalography data were recorded from 32 scalp locations, averaged across trials, and related to phases of the gait cycle based on the detection of left heel strike. A characteristic temporal pattern of positive and negative potentials, similar to movement-related cortical potentials, and related to the gait cycle was observed over the cortical leg representation area. Source localization analysis revealed that mainly the primary somatosensory, somatosensory association, primary motor and cingulate cortex were activated during walking. The negative peaks of the gait-related cortical potential were associated with activity predominantly in the cingulate and prefrontal cortex, while the primary motor, primary somatosensory and somatosensory association cortex were mainly active during the positive peaks. This study identified gait-related cortical potentials during walking. The results indicate a widely distributed cortical network involved in gait control.

  7. Expressing gait-line symmetry in able-bodied gait

    PubMed Central

    Jeleń, Piotr; Wit, Andrzej; Dudziński, Krzysztof; Nolan, Lee

    2008-01-01

    Background Gait-lines, or the co-ordinates of the progression of the point of application of the vertical ground reaction force, are a commonly reported parameter in most in-sole measuring systems. However, little is known about what is considered a "normal" or "abnormal" gait-line pattern or level of asymmetry. Furthermore, no reference databases on healthy young populations are available for this parameter. Thus the aim of this study is to provide such reference data in order to allow this tool to be better used in gait analysis. Methods Vertical ground reaction force data during several continuous gait cycles were collected using a Computer Dyno Graphy in-sole system® for 77 healthy young able-bodied subjects. A curve (termed gait-line) was obtained from the co-ordinates of the progression of the point of application of the force. An Asymmetry Coefficient Curve (AsC) was calculated between the mean gait-lines for the left and right foot for each subject. AsC limits of ± 1.96 and 3 standard deviations (SD) from the mean were then calculated. Gait-line data from 5 individual subjects displaying pathological gait due to disorders relating to the discopathy of the lumbar spine (three with considerable plantarflexor weakness, two with considerable dorsiflexor weakness) were compared to the AsC results from the able-bodied group. Results The ± 1.96 SD limit suggested that non-pathological gait falls within 12–16% asymmetry for gait-lines. Those exhibiting pathological gait fell outside both the ± 1.96 and ± 3SD limits at several points during stance. The subjects exhibiting considerable plantarflexor weakness all fell outside the ± 1.96SD limit from 30–50% of foot length to toe-off while those exhibiting considerable dorsiflexor weakness fell outside the ± 1.96SD limit between initial contact to 25–40% of foot length, and then surpassed the ± 3SD limit after 55–80% of foot length. Conclusion This analysis of gait-line asymmetry provides a reference

  8. Reciprocity relations in aerodynamics

    NASA Technical Reports Server (NTRS)

    Heaslet, Max A; Spreiter, John R

    1953-01-01

    Reverse flow theorems in aerodynamics are shown to be based on the same general concepts involved in many reciprocity theorems in the physical sciences. Reciprocal theorems for both steady and unsteady motion are found as a logical consequence of this approach. No restrictions on wing plan form or flight Mach number are made beyond those required in linearized compressible-flow analysis. A number of examples are listed, including general integral theorems for lifting, rolling, and pitching wings and for wings in nonuniform downwash fields. Correspondence is also established between the buildup of circulation with time of a wing starting impulsively from rest and the buildup of lift of the same wing moving in the reverse direction into a sharp-edged gust.

  9. Contractor safety training reciprocity

    SciTech Connect

    Melancon, R.

    1996-08-01

    In June, 1995, the National Petroleum Refiners Association (NPRA) adhoc committee on Contractor Safety Training, turned over the task of developing reciprocity agreements with all Contractor Safety Training Councils to the Executive Directors of each of the Council`s. The Council representatives were to develop these agreements based on the NPRA adhoc committee training objectives that were developed jointly by representatives of the petroleum industry, chemical industry, contractors and the Council`s.

  10. Geometric moments for gait description

    NASA Astrophysics Data System (ADS)

    Toxqui-Quitl, C.; Morales-Batalla, V.; Padilla-Vivanco, A.; Camacho-Bello, C.

    2013-09-01

    The optical flow associated with a set of digital images of a moving individual is analyzed in order to extract a gait signature. For this, invariant Hu moments are obtained for image description. A Hu Moment History (HMH) is obtained from K frames to describe the gait signature of individuals in a video. The gait descriptors are subsequences of the HMH of variable width. Each subsequence is generated by means of genetic algorithms and used for classification in a neuronal network. The database for algorithm evaluation is MoBo, and the gait classification results are above 90% for the cases of slow and fast walking and 100% for the cases of walking with a ball and inclined walking. An optical processor is also implemented in order to obtain the descriptors of the human gait.

  11. Effects of acceleration on gait measures in three horse gaits.

    PubMed

    Nauwelaerts, Sandra; Zarski, Lila; Aerts, Peter; Clayton, Hilary

    2015-05-01

    Animals switch gaits according to locomotor speed. In terrestrial locomotion, gaits have been defined according to footfall patterns or differences in center of mass (COM) motion, which characterizes mechanisms that are more general and more predictive than footfall patterns. This has generated different variables designed primarily to evaluate steady-speed locomotion, which is easier to standardize in laboratory conditions. However, in the ecology of an animal, steady-state conditions are rare and the ability to accelerate, decelerate and turn is essential. Currently, there are no data available that have tested whether COM variables can be used in accelerative or decelerative conditions. This study used a data set of kinematics and kinetics of horses using three gaits (walk, trot, canter) to evaluate the effects of acceleration (both positive and negative) on commonly used gait descriptors. The goal was to identify variables that distinguish between gaits both at steady state and during acceleration/deceleration. These variables will either be unaffected by acceleration or affected by it in a predictable way. Congruity, phase shift and COM velocity angle did not distinguish between gaits when the dataset included trials in unsteady conditions. Work (positive and negative) and energy recovery distinguished between gaits and showed a clear relationship with acceleration. Hodographs are interesting graphical representations to study COM mechanics, but they are descriptive rather than quantitative. Force angle, collision angle and collision fraction showed a U-shaped relationship with acceleration and seem promising tools for future research in unsteady conditions.

  12. Powered lower limb orthoses for gait rehabilitation

    PubMed Central

    Ferris, Daniel P.; Sawicki, Gregory S.; Domingo, Antoinette

    2006-01-01

    Bodyweight supported treadmill training has become a prominent gait rehabilitation method in leading rehabilitation centers. This type of locomotor training has many functional benefits but the labor costs are considerable. To reduce therapist effort, several groups have developed large robotic devices for assisting treadmill stepping. A complementary approach that has not been adequately explored is to use powered lower limb orthoses for locomotor training. Recent advances in robotic technology have made lightweight powered orthoses feasible and practical. An advantage to using powered orthoses as rehabilitation aids is they allow practice starting, turning, stopping, and avoiding obstacles during overground walking. PMID:16568153

  13. Terminology and forensic gait analysis.

    PubMed

    Birch, Ivan; Vernon, Wesley; Walker, Jeremy; Young, Maria

    2015-07-01

    The use of appropriate terminology is a fundamental aspect of forensic gait analysis. The language used in forensic gait analysis is an amalgam of that used in clinical practice, podiatric biomechanics and the wider field of biomechanics. The result can often be a lack of consistency in the language used, the definitions used and the clarity of the message given. Examples include the use of 'gait' and 'walking' as synonymous terms, confusion between 'step' and 'stride', the mixing of anatomical, positional and pathological descriptors, and inability to describe appropriately movements of major body segments such as the torso. The purpose of this paper is to share the well-established definitions of the fundamental parameters of gait, common to all professions, and advocate their use in forensic gait analysis to establish commonality. The paper provides guidance on the selection and use of appropriate terminology in the description of gait in the forensic context. This paper considers the established definitions of the terms commonly used, identifies those terms which have the potential to confuse readers, and suggests a framework of terminology which should be utilised in forensic gait analysis.

  14. Impaired gait in ankylosing spondylitis.

    PubMed

    Del Din, Silvia; Carraro, Elena; Sawacha, Zimi; Guiotto, Annamaria; Bonaldo, Lara; Masiero, Stefano; Cobelli, Claudio

    2011-07-01

    Ankylosing spondylitis (AS) is a chronic, inflammatory rheumatic disease. The spine becomes rigid from the occiput to the sacrum, leading to a stooped position. This study aims at evaluating AS subjects gait alterations. Twenty-four subjects were evaluated: 12 normal and 12 pathologic in stabilized anti-TNF-alpha treatment (mean age 49.42 (10.47), 25.44 (3.19) and mean body mass index 55.75 (3.19), 23.73 (2.7), respectively). Physical examination and gait analysis were performed. A motion capture system synchronized with two force plates was used. Three-dimensional kinematics and kinetics of trunk, pelvis, hip, knee and ankle were determined during gait. A trend towards reduction was found in gait velocity and stride length. Gait analysis results showed statistically significant alterations in the sagittal plane at each joint for AS patients (P < 0.049). Hip and knee joint extension moments showed a statistically significant reduction (P < 0.044). At the ankle joint, a decreased plantarflexion was assessed (P < 0.048) together with the absence of the heel rocker. Gait analysis, through gait alterations identification, allowed planning-specific rehabilitation intervention aimed to prevent patients' stiffness together with improve balance and avoid muscles' fatigue.

  15. An ultrafast reciprocating probe

    NASA Astrophysics Data System (ADS)

    Liu, Wenbin; Tan, Yi; Wang, Wenhao; Gao, Zhe

    2016-11-01

    For tokamak plasma diagnostics, an ultrafast reciprocating probe system driven by magnetic field coils, achieving a maximum velocity of 21 m/s, is introduced. The probes are attached with a driving hoop made of carbon steel and accelerated by three acceleration coils in series, then decelerated by two deceleration coils and buffer springs and return slowly. The coils with a current of about 1 kA generate a magnetic field of about 1 T. This probe system has been tested on the SUNIST (Sino-UNIted Spherical Tokamak) spherical tokamak. Radial profiles of the floating potential and other plasma parameters measured by this probe system are given.

  16. High pressure reciprocating pump

    SciTech Connect

    Besic, D.

    1990-05-01

    This patent describes an improvement in a reciprocating pump having a plunger and a pumping chamber. It comprises: the plunger having a bore communicating with an intersection opening and wherein the plunger incudes a central axis; a suction valve and a discharge valve, each having an axis of actuation parallel to a central axis of the plunger; the suction valve comprising a cylindrical core having a central passageway, and the core is slidably received by a seating member and resiliently biased to the seating member.

  17. Reciprocating magnetic refrigerator

    NASA Technical Reports Server (NTRS)

    Johnson, D. L.

    1985-01-01

    A 4 to 15 K magnetic refrigerator to test as an alternative to the Joule-Thomson circuit as the low temperature stage of a 4 to 300 K closed-cycle refrigerator was developed. The reciprocating magnetic refrigerator consists of two matrices of gadolinium gallium garnet spheres located in tandem on a single piston which alternately moves each matrix into a 7 telsa magnetic field. A separate helium gas circuit is used as the heat exchange mechanism for the low and the high temperature extremes of the magnetic refrigerator. Details of the design and results of the initial refrigerator component tests are presented.

  18. Dynamic markers of altered gait rhythm in amyotrophic lateral sclerosis

    NASA Technical Reports Server (NTRS)

    Hausdorff, J. M.; Lertratanakul, A.; Cudkowicz, M. E.; Peterson, A. L.; Kaliton, D.; Goldberger, A. L.

    2000-01-01

    Amyotrophic lateral sclerosis (ALS) is a disorder marked by loss of motoneurons. We hypothesized that subjects with ALS would have an altered gait rhythm, with an increase in both the magnitude of the stride-to-stride fluctuations and perturbations in the fluctuation dynamics. To test for this locomotor instability, we quantitatively compared the gait rhythm of subjects with ALS with that of normal controls and with that of subjects with Parkinson's disease (PD) and Huntington's disease (HD), pathologies of the basal ganglia. Subjects walked for 5 min at their usual pace wearing an ankle-worn recorder that enabled determination of the duration of each stride and of stride-to-stride fluctuations. We found that the gait of patients with ALS is less steady and more temporally disorganized compared with that of healthy controls. In addition, advanced ALS, HD, and PD were associated with certain common, as well as apparently distinct, features of altered stride dynamics. Thus stride-to-stride control of gait rhythm is apparently compromised with ALS. Moreover, a matrix of markers based on gait dynamics may be useful in characterizing certain pathologies of motor control and, possibly, in quantitatively monitoring disease progression and evaluating therapeutic interventions.

  19. Frequency-velocity mismatch: a fundamental abnormality in parkinsonian gait.

    PubMed

    Cho, Catherine; Kunin, Mikhail; Kudo, Koji; Osaki, Yasuhiro; Olanow, C Warren; Cohen, Bernard; Raphan, Theodore

    2010-03-01

    Gait dysfunction and falling are major sources of disability for patients with advanced Parkinson's disease (PD). It is presently thought that the fundamental defect is an inability to generate normal stride length. Our data suggest, however, that the basic problem in PD gait is an impaired ability to match step frequency to walking velocity. In this study, foot movements of PD and normal subjects were monitored with an OPTOTRAK motion-detection system while they walked on a treadmill at different velocities. PD subjects were also paced with auditory stimuli at different frequencies. PD gait was characterized by step frequencies that were faster and stride lengths that were shorter than those of normal controls. At low walking velocities, PD stepping had a reduced or absent terminal toe lift, which truncated swing phases, producing shortened steps. Auditory pacing was not able to normalize step frequency at these lower velocities. Peak forward toe velocities increased with walking velocity and PD subjects could initiate appropriate foot dynamics during initial phases of the swing. They could not control the foot appropriately in terminal phases, however. Increased treadmill velocity, which matched the natural PD step frequency, generated a second toe lift, normalizing step size. Levodopa increased the bandwidth of step frequencies, but was not as effective as increases in walking velocity in normalizing gait. We postulate that the inability to control step frequency and adjust swing phase dynamics to slower walking velocities are major causes for the gait impairment in PD.

  20. Reciprocal relations in electroacoustics

    SciTech Connect

    Chassagne, C.; Bedeaux, D.

    2014-07-28

    In a colloidal suspension, one can generate sound waves by the application of an alternating electric field (Electrokinetic Sonic Amplitude, i.e., ESA). Another phenomenon is electrophoresis (Electrophoretic Mobility, i.e., EM) where a colloidal particle moves relative to the solvent in an electric field. Vice versa one can generate electric fields or electric currents by sound waves (Colloid Vibration Potential/Current, i.e., CVP/CVI). In 1988 and 1990, O’Brien [J. Fluid Mech. 190, 71–86 (1988) and O’Brien, J. Fluid Mech. 212, 81–93 (1990)] derived a reciprocal relation between the proportionality coefficients of the EM and CVI phenomena. In this paper, we will generalize his proof by constructing the relevant entropy production from which the linear force-flux relations follow. General relations are derived for electrolyte solutions, of which colloidal suspensions are a particular case. The relations between CVI, CVP, EM, and ESA are discussed. O’Brien's reciprocal relation then follows as an Onsager relation. The relation is valid for any applied electric field frequency, particle surface charge and particle concentration (even in the presence of particle-particle interactions) provided the system is isotropic.

  1. Prediction of human gait parameters from temporal measures of foot-ground contact

    NASA Technical Reports Server (NTRS)

    Breit, G. A.; Whalen, R. T.

    1997-01-01

    Investigation of the influence of human physical activity on bone functional adaptation requires long-term histories of gait-related ground reaction force (GRF). Towards a simpler portable GRF measurement, we hypothesized that: 1) the reciprocal of foot-ground contact time (1/tc); or 2) the reciprocal of stride-period-normalized contact time (T/tc) predict peak vertical and horizontal GRF, loading rates, and horizontal speed during gait. GRF data were collected from 24 subjects while they walked and ran at a variety of speeds. Linear regression and ANCOVA determined the dependence of gait parameters on 1/tc and T/tc, and prediction SE. All parameters were significantly correlated to 1/tc and T/tc. The closest pooled relationship existed between peak running vertical GRF and T/tc (r2 = 0.896; SE = 3.6%) and improved with subject-specific regression (r2 = 0.970; SE = 2.2%). We conclude that temporal measures can predict force parameters of gait and may represent an alternative to direct GRF measurements for determining daily histories of habitual lower limb loading quantities necessary to quantify a bone remodeling stimulus.

  2. Walking to the beat of different drums: practical implications for the use of acoustic rhythms in gait rehabilitation.

    PubMed

    Roerdink, Melvyn; Bank, Paulina J M; Peper, C Lieke E; Beek, Peter J

    2011-04-01

    Acoustic rhythms are frequently used in gait rehabilitation, with positive instantaneous and prolonged transfer effects on various gait characteristics. The gait modifying ability of acoustic rhythms depends on how well gait is tied to the beat, which can be assessed with measures of relative timing of auditory-motor coordination. We examined auditory-motor coordination in 20 healthy elderly individuals walking to metronome beats with pacing frequencies slower than, equal to, and faster than their preferred cadence. We found that more steps were required to adjust gait to the beat, the more the metronome rate deviated from the preferred cadence. Furthermore, participants anticipated the beat with their footfalls to various degrees, depending on the metronome rate; the faster the tempo, the smaller the phase advance or phase lead. Finally, the variability in the relative timing between footfalls and the beat was smaller for metronome rates closer to the preferred cadence, reflecting superior auditory-motor coordination. These observations have three practical implications. First, instantaneous effects of acoustic stimuli on gait characteristics may typically be underestimated given the considerable number of steps required to attune gait to the beat in combination with the usual short walkways. Second, a systematic phase lead of footfalls to the beat does not necessarily reflect a reduced ability to couple gait to the metronome. Third, the efficacy of acoustic rhythms to modify gait depends on metronome rate. Gait is coupled best to the beat for metronome rates near the preferred cadence.

  3. Gait phase varies over velocities.

    PubMed

    Liu, Yancheng; Lu, Kun; Yan, Songhua; Sun, Ming; Lester, D Kevin; Zhang, Kuan

    2014-02-01

    We sought to characterize the percent (PT) of the phases of a gait cycle (GC) as velocity changes to establish norms for pathological gait characteristics with higher resolution technology. Ninety five healthy subjects (49 males and 46 females with age 34.9 ± 11.8 yrs, body weight 64.0 ± 11.7 kg and BMI 23.5 ± 3.6) were enrolled and walked comfortably on a 10-m walkway at self-selected slower, normal, and faster velocities. Walking was recorded with a high speed camera (250 frames per second) and the eight phases of a GC were determined by examination of individual frames for each subject. The correlation coefficients between the mean PT of the phases of the three velocities gaits and PT defined by previous publications were all greater than 0.99. The correlation coefficient between velocity and PT of gait phases is -0.83 for loading response (LR), -0.75 for mid stance (MSt), and -0.84 for pre-swing (PSw). While the PT of the phases of three velocities from this study are highly correlated with PT described by Dr. Jacquenlin Perry decades ago, actual PT of each phase varied amongst these individuals with the largest coefficient variation of 24.31% for IC with slower velocity. From slower to faster walk, the mean PT of MSt diminished from 35.30% to 25.33%. High resolution recording revealed ambiguity of some gait phase definitions, and these data may benefit GC characterization of normal and pathological gait in clinical practice. The study results indicate that one should consider individual variations and walking velocity when evaluating gaits of subjects using standard gait phase classification.

  4. [Clinical gait analysis: user guide].

    PubMed

    Armand, Stéphane; Bonnefoy-Mazure, Alice; Hoffmeyer, Pierre; De Coulon, Geraldo

    2015-10-14

    Clinical gait analysis has become an indispensable medical examination for the management of patients with complex gait disorders. As its name suggests, the purpose of this examination is to assess patients whilst they are walking in a laboratory setting. Measurements include: 3 dimensional joint motion, forces applied to joints, and electromyographic muscle activity. This quantitative data allows identification of walking deviations and to deduce the likely causes of these deviations thanks to the clinical data available for each patient.

  5. Toward a Behavior of Reciprocity

    PubMed Central

    Gernsbacher, Morton Ann

    2014-01-01

    It is frequently believed that autism is characterized by a lack of social or emotional reciprocity. In this article, I question that assumption by demonstrating how many professionals—researchers and clinicians—and likewise many parents, have neglected the true meaning of reciprocity. Reciprocity is “a relation of mutual dependence or action or influence,” or “a mode of exchange in which transactions take place between individuals who are symmetrically placed.” Assumptions by clinicians and researchers suggest that they have forgotten that reciprocity needs to be mutual and symmetrical—that reciprocity is a two-way street. Research is reviewed to illustrate that when professionals, peers, and parents are taught to act reciprocally, autistic children become more responsive. In one randomized clinical trial of “reciprocity training” to parents, their autistic children's language developed rapidly and their social engagement increased markedly. Other demonstrations of how parents and professionals can increase their behavior of reciprocity are provided. PMID:25598865

  6. Trust, Respect, and Reciprocity

    PubMed Central

    Phong, Tran Viet; Nhan, Le Nguyen Thanh; Dung, Nguyen Thanh; Ngan, Ta Thi Dieu; Kinh, Nguyen Van; Parker, Michael; Bull, Susan

    2015-01-01

    International science funders and publishers are driving a growing trend in data sharing. There is mounting pressure on researchers in low- and middle-income settings to conform to new sharing policies, despite minimal empirically grounded accounts of the ethical challenges of implementing the policies in these settings. This study used in-depth interviews and focus group discussions with 48 stakeholders in Vietnam to explore the experiences, attitudes, and expectations that inform ethical and effective approaches to sharing clinical research data. Distinct views on the role of trust, respect, and reciprocity were among those that emerged to inform culturally appropriate best practices. We conclude by discussing the challenges that authors of data-sharing policies should consider in this unique context. PMID:26297747

  7. Reciprocating linear motor

    NASA Technical Reports Server (NTRS)

    Goldowsky, Michael P. (Inventor)

    1987-01-01

    A reciprocating linear motor is formed with a pair of ring-shaped permanent magnets having opposite radial polarizations, held axially apart by a nonmagnetic yoke, which serves as an axially displaceable armature assembly. A pair of annularly wound coils having axial lengths which differ from the axial lengths of the permanent magnets are serially coupled together in mutual opposition and positioned with an outer cylindrical core in axial symmetry about the armature assembly. One embodiment includes a second pair of annularly wound coils serially coupled together in mutual opposition and an inner cylindrical core positioned in axial symmetry inside the armature radially opposite to the first pair of coils. Application of a potential difference across a serial connection of the two pairs of coils creates a current flow perpendicular to the magnetic field created by the armature magnets, thereby causing limited linear displacement of the magnets relative to the coils.

  8. Reciprocating wind engine

    SciTech Connect

    Van Mechelen, B.

    1980-12-09

    A reciprocating wind engine is described which utilizes plural, movably mounted sets of panels to form pistons. Cooperating first and second pistons may be spaced from each other on either side of a central crankshaft. As the wind strikes the surface of a first set of panels, the first piston is moved toward the crankshaft and the second piston is pulled toward the crankshaft from the opposite side. When both pistons are adjacent the crankshaft, the panels on the first or windward piston open to allow the wind to pass therethrough into contact with the panels of the second piston which are closed to present a uniform surface to the wind. The pistons are forced away from the crankshaft to complete one cycle of operation. The output from the crankshaft may be utilized to generate electricity, or for any other suitable purpose. Plural engine segments may be cooperatively joined together to form a bank of such units.

  9. How crouch gait can dynamically induce stiff-knee gait.

    PubMed

    van der Krogt, Marjolein M; Bregman, Daan J J; Wisse, Martijn; Doorenbosch, Caroline A M; Harlaar, Jaap; Collins, Steven H

    2010-04-01

    Children with cerebral palsy frequently experience foot dragging and tripping during walking due to a lack of adequate knee flexion in swing (stiff-knee gait). Stiff-knee gait is often accompanied by an overly flexed knee during stance (crouch gait). Studies on stiff-knee gait have mostly focused on excessive knee muscle activity during (pre)swing, but the passive dynamics of the limbs may also have an important effect. To examine the effects of a crouched posture on swing knee flexion, we developed a forward-dynamic model of human walking with a passive swing knee, capable of stable cyclic walking for a range of stance knee crouch angles. As crouch angle during stance was increased, the knee naturally flexed much less during swing, resulting in a 'stiff-knee' gait pattern and reduced foot clearance. Reduced swing knee flexion was primarily due to altered gravitational moments around the joints during initial swing. We also considered the effects of increased push-off strength and swing hip flexion torque, which both increased swing knee flexion, but the effect of crouch angle was dominant. These findings demonstrate that decreased knee flexion during swing can occur purely as the dynamical result of crouch, rather than from altered muscle function or pathoneurological control alone.

  10. Gait disturbances in dystrophic hamsters.

    PubMed

    Hampton, Thomas G; Kale, Ajit; Amende, Ivo; Tang, Wenlong; McCue, Scott; Bhagavan, Hemmi N; VanDongen, Case G

    2011-01-01

    The delta-sarcoglycan-deficient hamster is an excellent model to study muscular dystrophy. Gait disturbances, important clinically, have not been described in this animal model. We applied ventral plane videography (DigiGait) to analyze gait in BIO TO-2 dystrophic and BIO F1B control hamsters walking on a transparent treadmill belt. Stride length was ∼13% shorter (P < .05) in TO-2 hamsters at 9 months of age compared to F1B hamsters. Hindlimb propulsion duration, an indicator of muscle strength, was shorter in 9-month-old TO-2 (247 ± 8 ms) compared to F1B hamsters (272 ± 11 ms; P < .05). Braking duration, reflecting generation of ground reaction forces, was delayed in 9-month-old TO-2 (147 ± 6 ms) compared to F1B hamsters (126 ± 8 ms; P < .05). Hindpaw eversion, evidence of muscle weakness, was greater in 9-month-old TO-2 than in F1B hamsters (17.7 ± 1.2° versus 8.7 ± 1.6°; P < .05). Incline and decline walking aggravated gait disturbances in TO-2 hamsters at 3 months of age. Several gait deficits were apparent in TO-2 hamsters at 1 month of age. Quantitative gait analysis demonstrates that dystrophic TO-2 hamsters recapitulate functional aspects of human muscular dystrophy. Early detection of gait abnormalities in a convenient animal model may accelerate the development of therapies for muscular dystrophy.

  11. Upstream reciprocity in heterogeneous networks.

    PubMed

    Iwagami, Akio; Masuda, Naoki

    2010-08-01

    Many mechanisms for the emergence and maintenance of altruistic behavior in social dilemma situations have been proposed. Indirect reciprocity is one such mechanism, where other-regarding actions of a player are eventually rewarded by other players with whom the original player has not interacted. The upstream reciprocity (also called generalized indirect reciprocity) is a type of indirect reciprocity and represents the concept that those helped by somebody will help other unspecified players. In spite of the evidence for the enhancement of helping behavior by upstream reciprocity in rats and humans, theoretical support for this mechanism is not strong. In the present study, we numerically investigate upstream reciprocity in heterogeneous contact networks, in which the players generally have different number of neighbors. We show that heterogeneous networks considerably enhance cooperation in a game of upstream reciprocity. In heterogeneous networks, the most generous strategy, by which a player helps a neighbor on being helped and in addition initiates helping behavior, first occupies hubs in a network and then disseminates to other players. The scenario to achieve enhanced altruism resembles that seen in the case of the Prisoner's Dilemma game in heterogeneous networks.

  12. Healthy reciprocity in sexual interaction.

    PubMed

    Heino, J; Ojanlatva, A

    2000-02-01

    The purpose of the article is to discuss reciprocity in sexual interaction within a couple relationship in which heterosexual orientation is assumed and satisfaction considered. Reciprocity is modelled as an exchange of services which at its best functions as an unwritten contract, a mutual understanding regarding fairness of returned services, and a desire to comply with this principle together with a loved one/lover. An equal treatment of and balanced attitudes towards one another are present together with a just distribution of benefits and concessions or compromises. Reciprocity involves a relative term although healthy reciprocity can be defined for discussion and assessed as a degree of mutual satisfaction. Sexual interaction issues, skills to obtain satisfaction, and sexual and emotional compatibility are important elements in reciprocity. Understandable communication is an essential contributor in the implementation of reciprocity. Conflict-making dialogue should generally be avoided and connotive meanings of words taken into account. Erotophilia-erotophobia dimensions influence both the learning about and attitudes towards sexuality and contribute to personal and professional abilities to assess sexual problems and to attend to them. Erotic touch is a minimum requirement of love making. Sexual orientation, sexual desire, and intimacy influence sexual compatibility. Equity and exchange models are discussed, and a reciprocity model is proposed.

  13. Analysis of dual-task elderly gait in fallers and non-fallers using wearable sensors.

    PubMed

    Howcroft, Jennifer; Kofman, Jonathan; Lemaire, Edward D; McIlroy, William E

    2016-05-01

    Dual-task (DT) gait involves walking while simultaneously performing an attention-demanding task and can be used to identify impaired gait or executive function in older adults. Advancment is needed in techniques that quantify the influence of dual tasking to improve predictive and diagnostic potential. This study investigated the viability of wearable sensor measures to identify DT gait changes in older adults and distinguish between elderly fallers and non-fallers. A convenience sample of 100 older individuals (75.5±6.7 years; 76 non-fallers, 24 fallers based on 6 month retrospective fall occurrence) walked 7.62m under single-task (ST) and DT conditions while wearing pressure-sensing insoles and tri-axial accelerometers at the head, pelvis, and left and right shanks. Differences between ST and DT gait were identified for temporal measures, acceleration descriptive statistics, Fast Fourier Transform (FFT) quartiles, ratio of even to odd harmonics, center of pressure (CoP) stance path coefficient of variation, and deviations to expected CoP stance path. Increased posterior CoP stance path deviations, increased coefficient of variation, decreased FFT quartiles, and decreased ratio of even to odd harmonics suggested increased DT gait variability. Decreased gait velocity and decreased acceleration standard deviations (SD) at the pelvis and shanks could represent compensatory gait strategies that maintain stability. Differences in acceleration between fallers and non-fallers in head posterior SD and pelvis AP ratio of even to odd harmonics during ST, and pelvis vertical maximum Lyapunov exponent during DT gait were identified. Wearable-sensor-based DT gait assessments could be used in point-of-care environments to identify gait deficits.

  14. Gait analysis in forensic medicine

    NASA Astrophysics Data System (ADS)

    Larsen, Peter K.; Simonsen, Erik B.; Lynnerup, Niels

    2007-01-01

    We have combined the basic human ability to recognize other individuals with functional anatomical and biomechanical knowledge, in order to analyze the gait of perpetrators as recorded on surveillance video. The perpetrators are then compared with similar analyses of suspects. At present we give a statement to the police as to whether the perpetrator has a characteristic gait pattern compared to normal gait, and if a suspect has a comparable gait pattern. We have found agreements such as: limping, varus instability in the knee at heel strike, larger lateral flexion of the spinal column to one side than the other, inverted ankle during stance, pronounced sagittal head-movements, and marked head-shoulder posture. Based on these characteristic features, we state whether suspect and perpetrator could have the same identity but it is not possible to positively identify the perpetrator. Nevertheless, we have been involved in several cases where the court has found that this type of gait analysis, especially combined with photogrammetry, was a valuable tool. The primary requisites are surveillance cameras recording with sufficient frequency, ideally about 15 Hz, which are positioned in frontal and preferably also in profile view.

  15. A Global Gait Asymmetry Index.

    PubMed

    Cabral, Silvia; Resende, Renan A; Clansey, Adam C; Deluzio, Kevin J; Selbie, W Scott; Veloso, António P

    2016-04-01

    High levels of gait asymmetry are associated with many pathologies. Our long-term goal is to improve gait symmetry through real-time biofeedback of a symmetry index. Symmetry is often reported as a single metric or a collective signature of multiple discrete measures. While this is useful for assessment, incorporating multiple feedback metrics presents too much information for most subjects to use as visual feedback for gait retraining. The aim of this article was to develop a global gait asymmetry (GGA) score that could be used as a biofeedback metric for gait retraining and to test the effectiveness of the GGA for classifying artificially-induced asymmetry. Eighteen participants (11 males; age 26.9 y [SD = 7.7]; height 1.8 m [SD = 0.1]; body mass 72.7 kg [SD = 8.9]) walked on a treadmill in 3 symmetry conditions, induced by wearing custom-made sandals: a symmetric condition (identical sandals) and 2 asymmetric conditions (different sandals). The GGA score was calculated, based on several joint angles, and compared between conditions. Significant differences were found among all conditions (P < .001), meaning that the GGA score is sensitive to different levels of asymmetry, and may be useful for rehabilitation and assessment.

  16. A Global Gait Asymmetry Index.

    PubMed

    Cabral, Silvia; Resende, Renan A; Clansey, Adam C; Deluzio, Kevin J; Selbie, W Scott; Veloso, António P

    2016-04-01

    High levels of gait asymmetry are associated with many pathologies. Our long-term goal is to improve gait symmetry through real-time biofeedback of a symmetry index. Symmetry is often reported as a single metric or a collective signature of multiple discrete measures. While this is useful for assessment, incorporating multiple feedback metrics presents too much information for most subjects to use as visual feedback for gait retraining. The aim of this article was to develop a global gait asymmetry (GGA) score that could be used as a biofeedback metric for gait retraining and to test the effectiveness of the GGA for classifying artificially-induced asymmetry. Eighteen participants (11 males; age 26.9 y [SD = 7.7]; height 1.8 m [SD = 0.1]; body mass 72.7 kg [SD = 8.9]) walked on a treadmill in 3 symmetry conditions, induced by wearing custom-made sandals: a symmetric condition (identical sandals) and 2 asymmetric conditions (different sandals). The GGA score was calculated, based on several joint angles, and compared between conditions. Significant differences were found among all conditions (P < .001), meaning that the GGA score is sensitive to different levels of asymmetry, and may be useful for rehabilitation and assessment. PMID:26502455

  17. Direct reciprocity in spatial populations enhances R-reciprocity as well as ST-reciprocity.

    PubMed

    Miyaji, Kohei; Tanimoto, Jun; Wang, Zhen; Hagishima, Aya; Ikegaya, Naoki

    2013-01-01

    As is well-known, spatial reciprocity plays an important role in facilitating the emergence of cooperative traits, and the effect of direct reciprocity is also obvious for explaining the cooperation dynamics. However, how the combination of these two scenarios influences cooperation is still unclear. In the present work, we study the evolution of cooperation in 2 × 2 games via considering both spatial structured populations and direct reciprocity driven by the strategy with 1-memory length. Our results show that cooperation can be significantly facilitated on the whole parameter plane. For prisoner's dilemma game, cooperation dominates the system even at strong dilemma, where maximal social payoff is still realized. In this sense, R-reciprocity forms and it is robust to the extremely strong dilemma. Interestingly, when turning to chicken game, we find that ST-reciprocity is also guaranteed, through which social average payoff and cooperation is greatly enhanced. This reciprocity mechanism is supported by mean-field analysis and different interaction topologies. Thus, our study indicates that direct reciprocity in structured populations can be regarded as a more powerful factor for the sustainability of cooperation.

  18. Direct reciprocity in spatial populations enhances R-reciprocity as well as ST-reciprocity.

    PubMed

    Miyaji, Kohei; Tanimoto, Jun; Wang, Zhen; Hagishima, Aya; Ikegaya, Naoki

    2013-01-01

    As is well-known, spatial reciprocity plays an important role in facilitating the emergence of cooperative traits, and the effect of direct reciprocity is also obvious for explaining the cooperation dynamics. However, how the combination of these two scenarios influences cooperation is still unclear. In the present work, we study the evolution of cooperation in 2 × 2 games via considering both spatial structured populations and direct reciprocity driven by the strategy with 1-memory length. Our results show that cooperation can be significantly facilitated on the whole parameter plane. For prisoner's dilemma game, cooperation dominates the system even at strong dilemma, where maximal social payoff is still realized. In this sense, R-reciprocity forms and it is robust to the extremely strong dilemma. Interestingly, when turning to chicken game, we find that ST-reciprocity is also guaranteed, through which social average payoff and cooperation is greatly enhanced. This reciprocity mechanism is supported by mean-field analysis and different interaction topologies. Thus, our study indicates that direct reciprocity in structured populations can be regarded as a more powerful factor for the sustainability of cooperation. PMID:23951272

  19. A mechanical energy analysis of gait initiation

    NASA Technical Reports Server (NTRS)

    Miller, C. A.; Verstraete, M. C.

    1999-01-01

    The analysis of gait initiation (the transient state between standing and walking) is an important diagnostic tool to study pathologic gait and to evaluate prosthetic devices. While past studies have quantified mechanical energy of the body during steady-state gait, to date no one has computed the mechanical energy of the body during gait initiation. In this study, gait initiation in seven normal male subjects was studied using a mechanical energy analysis to compute total body energy. The data showed three separate states: quiet standing, gait initiation, and steady-state gait. During gait initiation, the trends in the energy data for the individual segments were similar to those seen during steady-state gait (and in Winter DA, Quanbury AO, Reimer GD. Analysis of instantaneous energy of normal gait. J Biochem 1976;9:253-257), but diminished in amplitude. However, these amplitudes increased to those seen in steady-state during the gait initiation event (GIE), with the greatest increase occurring in the second step due to the push-off of the foundation leg. The baseline level of mechanical energy was due to the potential energy of the individual segments, while the cyclic nature of the data was indicative of the kinetic energy of the particular leg in swing phase during that step. The data presented showed differences in energy trends during gait initiation from those of steady state, thereby demonstrating the importance of this event in the study of locomotion.

  20. Gait Stability in Children with Cerebral Palsy

    ERIC Educational Resources Information Center

    Bruijn, Sjoerd M.; Millard, Matthew; van Gestel, Leen; Meyns, Pieter; Jonkers, Ilse; Desloovere, Kaat

    2013-01-01

    Children with unilateral Cerebral Palsy (CP) have several gait impairments, amongst which impaired gait stability may be one. We tested whether a newly developed stability measure (the foot placement estimator, FPE) which does not require long data series, can be used to asses gait stability in typically developing (TD) children as well as…

  1. Social evolution: reciprocity there is.

    PubMed

    Taborsky, Michael

    2013-06-01

    The theory of cooperation predicts that altruism can be established by reciprocity, yet empirical evidence from nature is contentious. Increasingly though, experimental results from social vertebrates challenge the nearly exclusive explanatory power of relatedness for the evolution of cooperation.

  2. Group formation through indirect reciprocity

    NASA Astrophysics Data System (ADS)

    Oishi, Koji; Shimada, Takashi; Ito, Nobuyasu

    2013-03-01

    The emergence of group structure of cooperative relations is studied in an agent-based model. It is proved that specific types of reciprocity norms lead individuals to split into two groups only inside of which they are cooperative. The condition for the evolutionary stability of the norms is also obtained. This result suggests reciprocity norms, which usually promote cooperation, can cause society's separation into multiple groups.

  3. Moral assessment in indirect reciprocity.

    PubMed

    Sigmund, Karl

    2012-04-21

    Indirect reciprocity is one of the mechanisms for cooperation, and seems to be of particular interest for the evolution of human societies. A large part is based on assessing reputations and acting accordingly. This paper gives a brief overview of different assessment rules for indirect reciprocity, and studies them by using evolutionary game dynamics. Even the simplest binary assessment rules lead to complex outcomes and require considerable cognitive abilities.

  4. 32 CFR 148.1 - Intergency reciprocal acceptance .

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... reciprocal acceptance of security policies and procedures for approving, accrediting, and maintaining the secure posture of shared facilities will reduce aggregate costs, promote interoperability of agency security systems, preserve vitality of the U.S. industrial base, and advance national security objectives....

  5. Pneumatic interactive gait rehabilitation orthosis: design and preliminary testing.

    PubMed

    Belforte, G; Eula, G; Appendino, S; Sirolli, S

    2011-02-01

    Motor rehabilitation techniques based on passive movement of the lower limbs have been developed over the past 15 years. Gait training automation is the latest innovation in these techniques. This paper describes the design and development of a pneumatic interactive gait rehabilitation orthosis (PIGRO), as well as the first experimental results obtained with healthy subjects. PIGRO consists of a modular and size-adaptable exoskeleton, pneumatic actuation systems for the six actuated degrees of freedom (DoF), and a control unit. The foot orthosis and ankle actuation can be removed and/or replaced with orthopaedic shoes so as to permit gait rehabilitation while advancing between parallel bars with ground contact and partial body weight support (i.e. not walking in place). Control logic provides closed-loop position control independently on each joint, with position feedback for each joint in real time. Imposed curves are physiological joint angles: it is also possible to choose between activating one or both legs and to modify curves to obtain different gait patterns if required. The paper concludes with a presentation of experimental results for the device's performance.

  6. Human gait recognition via deterministic learning.

    PubMed

    Zeng, Wei; Wang, Cong

    2012-11-01

    Recognition of temporal/dynamical patterns is among the most difficult pattern recognition tasks. Human gait recognition is a typical difficulty in the area of dynamical pattern recognition. It classifies and identifies individuals by their time-varying gait signature data. Recently, a new dynamical pattern recognition method based on deterministic learning theory was presented, in which a time-varying dynamical pattern can be effectively represented in a time-invariant manner and can be rapidly recognized. In this paper, we present a new model-based approach for human gait recognition via the aforementioned method, specifically for recognizing people by gait. The approach consists of two phases: a training (learning) phase and a test (recognition) phase. In the training phase, side silhouette lower limb joint angles and angular velocities are selected as gait features. A five-link biped model for human gait locomotion is employed to demonstrate that functions containing joint angle and angular velocity state vectors characterize the gait system dynamics. Due to the quasi-periodic and symmetrical characteristics of human gait, the gait system dynamics can be simplified to be described by functions of joint angles and angular velocities of one side of the human body, thus the feature dimension is effectively reduced. Locally-accurate identification of the gait system dynamics is achieved by using radial basis function (RBF) neural networks (NNs) through deterministic learning. The obtained knowledge of the approximated gait system dynamics is stored in constant RBF networks. A gait signature is then derived from the extracted gait system dynamics along the phase portrait of joint angles versus angular velocities. A bank of estimators is constructed using constant RBF networks to represent the training gait patterns. In the test phase, by comparing the set of estimators with the test gait pattern, a set of recognition errors are generated, and the average L(1) norms

  7. Gait ataxia in essential tremor is differentially modulated by thalamic stimulation.

    PubMed

    Fasano, Alfonso; Herzog, Jan; Raethjen, Jan; Rose, Franziska E M; Muthuraman, Muthuraman; Volkmann, Jens; Falk, Daniela; Elble, Rodger; Deuschl, Günther

    2010-12-01

    Patients with advanced stages of essential tremor frequently exhibit tandem gait ataxia with impaired balance control and imprecise foot placement, resembling patients with a cerebellar deficit. Thalamic deep brain stimulation, a surgical therapy for otherwise intractable cases, has been shown to improve tremor, but its impact on cerebellar-like gait difficulties remains to be elucidated. Eleven patients affected by essential tremor (five females; age 69.8 ± 3.9 years; disease duration 24.4 ± 11.2 years; follow-up after surgery 24.7 ± 20.3 months) were evaluated during the following conditions: stimulation off, stimulation on and supra-therapeutic stimulation. Ten age-matched healthy controls served as the comparison group. Locomotion by patients and controls was assessed with (i) overground gait and tandem gait; (ii) balance-assisted treadmill tandem gait and (iii) unassisted treadmill gait. The two treadmill paradigms were kinematically analysed using a 3D opto-electronic motion analysis system. Established clinical and kinesiological measures of ataxia were computed. During stimulation off, the patients exhibited ataxia in all assessment paradigms, which improved during stimulation on and worsened again during supra-therapeutic stimulation. During over ground tandem gait, patients had more missteps and slower gait velocities during stimulation off and supra-therapeutic stimulation than during stimulation on. During balance-assisted tandem gait, stimulation on reduced the temporospatial variability in foot trajectories to nearly normal values, while highly variable (ataxic) foot trajectories were observed during stimulation off and supra-therapeutic stimulation. During unassisted treadmill gait, stimulation on improved gait stability compared with stimulation off and supra-therapeutic stimulation, as demonstrated by increased gait velocity and ankle rotation. These improvements in ataxia were not a function of reduced tremor in the lower limbs or torso. In

  8. Gait characterization for osteoarthritis patients using wearable gait sensors (H-Gait systems).

    PubMed

    Tadano, Shigeru; Takeda, Ryo; Sasaki, Keita; Fujisawa, Tadashi; Tohyama, Harukazu

    2016-03-21

    The objective of this work was to investigate the possibilities of using the wearable sensors-based H-Gait system in an actual clinical trial and proposes new gait parameters for characterizing OA gait. Seven H-Gait sensors, consisting of tri-axial inertial sensors, were attached to seven lower limb body segments (pelvis, both thighs, both shanks and both feet). The acceleration and angular velocity data measured were used to estimate three-dimensional kinematic parameters of patients during level walking. Three new parameters were proposed to assess the severity of OA based on the characteristics of these joint center trajectories in addition to conventional gait spatio-temporal parameters. The experiment was conducted on ten subjects with knee OA. The kinematic results obtained (hip, knee and ankle joint angles, joint trajectory in the horizontal and sagittal planes) were compared with those from a reference healthy (control) group. As a result, the angle between the right and left knee trajectories along with that of the ankle joint trajectories were almost twice as large (21.3° vs. 11.6° and 14.9° vs. 7.8°) compared to those of the healthy subjects. In conclusion, it was found that the ankle joints during stance abduct less to avoid adduction at the knee as the severity of OA increases and lead to more acute angles (less parallel) between the right and left knee/ankle joints in the horizontal plane. This method was capable to provide quantitative information about the gait of OA patients and has the advantage to allow for out-of-laboratory monitoring.

  9. Normative Spatiotemporal Gait Parameters in Older Adults

    PubMed Central

    Hollman, John H.; McDade, Eric M.; Petersen, Ronald C.

    2011-01-01

    While factor analyses have characterized pace, rhythm and variability as factors that explain variance in gait performance in older adults, comprehensive analyses incorporating many gait parameters have not been undertaken and normative data for many of those parameters are lacking. The purposes of this study were to conduct a factor analysis on nearly two dozen spatiotemporal gait parameters and to contribute to the normative database of gait parameters from healthy, able-bodied men and women over the age of 70. Data were extracted from 294 participants enrolled in the Mayo Clinic Study of Aging. Spatiotemporal gait data were obtained as participants completed two walks across a 5.6-m electronic walkway (GAITRite®). Five primary domains of spatiotemporal gait performance were identified: a “rhythm” domain was characterized by cadence and temporal parameters such as stride time; a “phase” domain was characterized by temporophasic parameters that constitute distinct divisions of the gait cycle; a “variability” domain encompassed gait cycle and step variability parameters; a “pace” domain was characterized by parameters that included gait speed, step length and stride length; and a “base of support” domain was characterized by step width and step width variability. Several domains differed between men and women and differed across age groups. Reference values of 23 gait parameters are presented which researchers or clinicians can use for assessing and interpreting gait dysfunction in aging persons. PMID:21531139

  10. An Efficient Gait Recognition with Backpack Removal

    NASA Astrophysics Data System (ADS)

    Lee, Heesung; Hong, Sungjun; Kim, Euntai

    2009-12-01

    Gait-based human identification is a paradigm to recognize individuals using visual cues that characterize their walking motion. An important requirement for successful gait recognition is robustness to variations including different lighting conditions, poses, and walking speed. Deformation of the gait silhouette caused by objects carried by subjects also has a significant effect on the performance of gait recognition systems; a backpack is the most common of these objects. This paper proposes methods for eliminating the effect of a carried backpack for efficient gait recognition. We apply simple, recursive principal component analysis (PCA) reconstructions and error compensation to remove the backpack from the gait representation and then conduct gait recognition. Experiments performed with the CASIA database illustrate the performance of the proposed algorithm.

  11. Nonlinear dynamical model of human gait.

    PubMed

    West, Bruce J; Scafetta, Nicola

    2003-05-01

    We present a nonlinear dynamical model of the human gait control system in a variety of gait regimes. The stride-interval time series in normal human gait is characterized by slightly multifractal fluctuations. The fractal nature of the fluctuations becomes more pronounced under both an increase and decrease in the average gait. Moreover, the long-range memory in these fluctuations is lost when the gait is keyed on a metronome. Human locomotion is controlled by a network of neurons capable of producing a correlated syncopated output. The central nervous system is coupled to the motocontrol system, and together they control the locomotion of the gait cycle itself. The metronomic gait is simulated by a forced nonlinear oscillator with a periodic external force associated with the conscious act of walking in a particular way. PMID:12786188

  12. Nonlinear dynamical model of human gait

    NASA Astrophysics Data System (ADS)

    West, Bruce J.; Scafetta, Nicola

    2003-05-01

    We present a nonlinear dynamical model of the human gait control system in a variety of gait regimes. The stride-interval time series in normal human gait is characterized by slightly multifractal fluctuations. The fractal nature of the fluctuations becomes more pronounced under both an increase and decrease in the average gait. Moreover, the long-range memory in these fluctuations is lost when the gait is keyed on a metronome. Human locomotion is controlled by a network of neurons capable of producing a correlated syncopated output. The central nervous system is coupled to the motocontrol system, and together they control the locomotion of the gait cycle itself. The metronomic gait is simulated by a forced nonlinear oscillator with a periodic external force associated with the conscious act of walking in a particular way.

  13. Methods to temporally align gait cycle data.

    PubMed

    Helwig, Nathaniel E; Hong, Sungjin; Hsiao-Wecksler, Elizabeth T; Polk, John D

    2011-02-01

    The need for the temporal alignment of gait cycle data is well known; however, there is little consensus concerning which alignment method to use. In this paper, we discuss the pros and cons of some methods commonly applied to temporally align gait cycle data (normalization to percent gait cycle, dynamic time warping, derivative dynamic time warping, and piecewise alignment methods). In addition, we empirically evaluate these different methods' abilities to produce successful temporal alignment when mapping a test gait cycle trajectory to a target trajectory. We demonstrate that piecewise temporal alignment techniques outperform other commonly used alignment methods (normalization to percent gait cycle, dynamic time warping, and derivative dynamic time warping) in typical biomechanical and clinical alignment tasks. Lastly, we present an example of how these piecewise alignment techniques make it possible to separately examine intensity and temporal differences between gait cycle data throughout the entire gait cycle, which can provide greater insight into the complexities of movement patterns.

  14. On using gait in forensic biometrics.

    PubMed

    Bouchrika, Imed; Goffredo, Michaela; Carter, John; Nixon, Mark

    2011-07-01

    Given the continuing advances in gait biometrics, it appears prudent to investigate the translation of these techniques for forensic use. We address the question as to the confidence that might be given between any two such measurements. We use the locations of ankle, knee, and hip to derive a measure of the match between walking subjects in image sequences. The Instantaneous Posture Match algorithm, using Harr templates, kinematics, and anthropomorphic knowledge is used to determine their location. This is demonstrated using real CCTV recorded at Gatwick International Airport, laboratory images from the multiview CASIA-B data set, and an example of real scene of crime video. To access the measurement confidence, we study the mean intra- and inter-match scores as a function of database size. These measures converge to constant and separate values, indicating that the match measure derived from individual comparisons is considerably smaller than the average match measure from a population.

  15. Speed-Dependent Modulation of the Locomotor Behavior in Adult Mice Reveals Attractor and Transitional Gaits

    PubMed Central

    Lemieux, Maxime; Josset, Nicolas; Roussel, Marie; Couraud, Sébastien; Bretzner, Frédéric

    2016-01-01

    Locomotion results from an interplay between biomechanical constraints of the muscles attached to the skeleton and the neuronal circuits controlling and coordinating muscle activities. Quadrupeds exhibit a wide range of locomotor gaits. Given our advances in the genetic identification of spinal and supraspinal circuits important to locomotion in the mouse, it is now important to get a better understanding of the full repertoire of gaits in the freely walking mouse. To assess this range, young adult C57BL/6J mice were trained to walk and run on a treadmill at different locomotor speeds. Instead of using the classical paradigm defining gaits according to their footfall pattern, we combined the inter-limb coupling and the duty cycle of the stance phase, thus identifying several types of gaits: lateral walk, trot, out-of-phase walk, rotary gallop, transverse gallop, hop, half-bound, and full-bound. Out-of-phase walk, trot, and full-bound were robust and appeared to function as attractor gaits (i.e., a state to which the network flows and stabilizes) at low, intermediate, and high speeds respectively. In contrast, lateral walk, hop, transverse gallop, rotary gallop, and half-bound were more transient and therefore considered transitional gaits (i.e., a labile state of the network from which it flows to the attractor state). Surprisingly, lateral walk was less frequently observed. Using graph analysis, we demonstrated that transitions between gaits were predictable, not random. In summary, the wild-type mouse exhibits a wider repertoire of locomotor gaits than expected. Future locomotor studies should benefit from this paradigm in assessing transgenic mice or wild-type mice with neurotraumatic injury or neurodegenerative disease affecting gait. PMID:26941592

  16. Direct reciprocity in structured populations.

    PubMed

    van Veelen, Matthijs; García, Julián; Rand, David G; Nowak, Martin A

    2012-06-19

    Reciprocity and repeated games have been at the center of attention when studying the evolution of human cooperation. Direct reciprocity is considered to be a powerful mechanism for the evolution of cooperation, and it is generally assumed that it can lead to high levels of cooperation. Here we explore an open-ended, infinite strategy space, where every strategy that can be encoded by a finite state automaton is a possible mutant. Surprisingly, we find that direct reciprocity alone does not lead to high levels of cooperation. Instead we observe perpetual oscillations between cooperation and defection, with defection being substantially more frequent than cooperation. The reason for this is that "indirect invasions" remove equilibrium strategies: every strategy has neutral mutants, which in turn can be invaded by other strategies. However, reciprocity is not the only way to promote cooperation. Another mechanism for the evolution of cooperation, which has received as much attention, is assortment because of population structure. Here we develop a theory that allows us to study the synergistic interaction between direct reciprocity and assortment. This framework is particularly well suited for understanding human interactions, which are typically repeated and occur in relatively fluid but not unstructured populations. We show that if repeated games are combined with only a small amount of assortment, then natural selection favors the behavior typically observed among humans: high levels of cooperation implemented using conditional strategies.

  17. Indirect Reciprocity; A Field Experiment

    PubMed Central

    van Apeldoorn, Jacobien; Schram, Arthur

    2016-01-01

    Indirect reciprocity involves cooperative acts towards strangers, either in response to their kindness to third parties (downstream) or after receiving kindness from others oneself (upstream). It is considered to be important for the evolution of cooperative behavior amongst humans. Though it has been widely studied theoretically, the empirical evidence of indirect reciprocity has thus far been limited and based solely on behavior in laboratory experiments. We provide evidence from an online environment where members can repeatedly ask and offer services to each other, free of charge. For the purpose of this study we created several new member profiles, which differ only in terms of their serving history. We then sent out a large number of service requests to different members from all over the world. We observe that a service request is more likely to be rewarded for those with a profile history of offering the service (to third parties) in the past. This provides clear evidence of (downstream) indirect reciprocity. We find no support for upstream indirect reciprocity (in this case, rewarding the service request after having previously received the service from third parties), however. Our evidence of downstream indirect reciprocity cannot be attributed to reputational effects concerning one’s trustworthiness as a service user. PMID:27043712

  18. Assortment and the evolution of generalized reciprocity.

    PubMed

    Rankin, Daniel J; Taborsky, Michael

    2009-07-01

    Reciprocity is often invoked to explain cooperation. Reciprocity is cognitively demanding, and both direct and indirect reciprocity require that individuals store information about the propensity of their partners to cooperate. By contrast, generalized reciprocity, wherein individuals help on the condition that they received help previously, only relies on whether an individual received help in a previous encounter. Such anonymous information makes generalized reciprocity hard to evolve in a well-mixed population, as the strategy will lose out to pure defectors. Here we analyze a model for the evolution of generalized reciprocity, incorporating assortment of encounters, to investigate the conditions under which it will evolve. We show that, in a well-mixed population, generalized reciprocity cannot evolve. However, incorporating assortment of encounters can favor the evolution of generalized reciprocity in which indiscriminate cooperation and defection are both unstable. We show that generalized reciprocity can evolve under both the prisoner's dilemma and the snowdrift game.

  19. Effect of prolonged free-walking fatigue on gait and physiological rhythm.

    PubMed

    Yoshino, Kohzoh; Motoshige, Tomoko; Araki, Tsutomu; Matsuoka, Katsunori

    2004-08-01

    This study examined the ways in which gait patterns and physiological rhythms such as those of muscle activity (tibialis anterior (TA) and biceps femoris (BF)) and cardiac activity are affected by the fatigue induced by prolonged free walking. Twelve normal subjects who walked for 3 h at their preferred pace were divided into two groups according to whether their mean gait cycle time (reciprocal of stride rate) during the second 90 min was higher (Group A: n=8) or lower (Group B: n=4) than that during the first 90 min. For Group A, the level of subjective fatigue during the walking task was significantly higher and the heart rate at rest was significantly lower than Group B. In Group A, prolonged walking significantly decreased the mean power frequency of the electromyography from TA, increased the variability of gait rhythm, decreased the largest Lyapunov exponent of the vertical component of back-waist acceleration, and decreased the amplitude of the vertical component of back-waist acceleration. Taking the onset timings of these changes into account, we propose that subjects who tire easily during prolonged walking first show local muscle fatigue at TA followed by instability of gait rhythm and then they slow their gait rhythm to enhance local dynamic stability. For both groups we constructed a physical fatigue index described by linear regression of gait and physiological variables. When we compared the subjective fatigue level with the fatigue level predicted using the index, we obtained a relatively high correlation coefficient for both groups (r=0.77).

  20. Genetic feature selection for gait recognition

    NASA Astrophysics Data System (ADS)

    Tafazzoli, Faezeh; Bebis, George; Louis, Sushil; Hussain, Muhammad

    2015-01-01

    Many research studies have demonstrated that gait can serve as a useful biometric modality for human identification at a distance. Traditional gait recognition systems, however, have mostly been evaluated without explicitly considering the most relevant gait features, which might have compromised performance. We investigate the problem of selecting a subset of the most relevant gait features for improving gait recognition performance. This is achieved by discarding redundant and irrelevant gait features while preserving the most informative ones. Motivated by our previous work on feature subset selection using genetic algorithms (GAs), we propose using GAs to select an optimal subset of gait features. First, features are extracted using kernel principal component analysis (KPCA) on spatiotemporal projections of gait silhouettes. Then, GA is applied to select a subset of eigenvectors in KPCA space that best represents a subject's identity. Each gait pattern is then represented by projecting it only on the eigenvectors selected by the GA. To evaluate the effectiveness of the selected features, we have experimented with two different classifiers: k nearest-neighbor and Naïve Bayes classifier. We report considerable gait recognition performance improvements on the Georgia Tech and CASIA databases.

  1. Rehabilitation in limb deficiency. 1. Gait and motion analysis.

    PubMed

    Czerniecki, J M

    1996-03-01

    This self-directed learning module highlights new advances in this topic area. It is part of the chapter on rehabilitation in limb deficiency in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. This article discusses normal gait, the influence of prosthetic alignment on amputee function, and the effects of prosthetic components on the metabolic costs and the biomechanical function of the amputee. The biomechanics of normal ambulation are presented as a background to enable the practitioner to gain an understanding of the typical gait adaptations that occur in below-knee and above-knee amputees. The effects of newer prosthetic components and socket designs on the biomechanical adaptations are reviewed. The metabolic costs of amputee ambulation are significantly greater than normal. The theoretical mechanisms for this are discussed, and the effects of newer socket designs, ultra-light-weight components, and energy-storing prosthetic components are presented.

  2. Human identification using temporal information preserving gait template.

    PubMed

    Wang, Chen; Zhang, Junping; Wang, Liang; Pu, Jian; Yuan, Xiaoru

    2012-11-01

    Gait Energy Image (GEI) is an efficient template for human identification by gait. However, such a template loses temporal information in a gait sequence, which is critical to the performance of gait recognition. To address this issue, we develop a novel temporal template, named Chrono-Gait Image (CGI), in this paper. The proposed CGI template first extracts the contour in each gait frame, followed by encoding each of the gait contour images in the same gait sequence with a multichannel mapping function and compositing them to a single CGI. To make the templates robust to a complex surrounding environment, we also propose CGI-based real and synthetic temporal information preserving templates by using different gait periods and contour distortion techniques. Extensive experiments on three benchmark gait databases indicate that, compared with the recently published gait recognition approaches, our CGI-based temporal information preserving approach achieves competitive performance in gait recognition with robustness and efficiency. PMID:22201053

  3. Lever arm dysfunction in cerebral palsy gait.

    PubMed

    Theologis, Tim

    2013-11-01

    Skeletal structures act as lever arms during walking. Muscle activity and the ground reaction against gravity exert forces on the skeleton, which generate torque (moments) around joints. These lead to the sequence of movements which form normal human gait. Skeletal deformities in cerebral palsy (CP) affect the function of bones as lever arms and compromise gait. Lever arm dysfunction should be carefully considered when contemplating treatment to improve gait in children with CP.

  4. Indirect reciprocity with optional interactions.

    PubMed

    Ghang, Whan; Nowak, Martin A

    2015-01-21

    Indirect reciprocity is a mechanism for the evolution of cooperation that is relevant for prosocial behavior among humans. Indirect reciprocity means that my behavior towards you also depends on what you have done to others. Indirect reciprocity is associated with the evolution of social intelligence and human language. Most approaches to indirect reciprocity assume obligatory interactions, but here we explore optional interactions. In any one round a game between two players is offered. A cooperator accepts a game unless the reputation of the other player indicates a defector. For a game to take place, both players must accept. In a game between a cooperator and a defector, the reputation of the defector is revealed to all players with probability Q. After a sufficiently large number of rounds the identity of all defectors is known and cooperators are no longer exploited. The crucial condition for evolution of cooperation can be written as hQB>1, where h is the average number of rounds per person and B=(b/c)-1 specifies the benefit-to-cost ratio. We analyze both stochastic and deterministic evolutionary game dynamics. We study two extensions that deal with uncertainty: hesitation and malicious gossip.

  5. Do infants detect indirect reciprocity?

    PubMed

    Meristo, Marek; Surian, Luca

    2013-10-01

    In social interactions involving indirect reciprocity, agent A acts prosocially towards B and this prompts C to act prosocially towards A. This happens because A's actions enhanced its reputation in the eyes of third parties. Indirect reciprocity may have been of central importance in the evolution of morality as one of the major mechanisms leading to the selection of helping and fair attitudes. Here we show that 10-month-old infants expect third parties to act positively towards fair donors who have distributed attractive resources equally between two recipients, rather than toward unfair donors who made unequal distributions. Infants' responses were dependent on the reciprocator's perceptual exposure to previous relevant events: they expected the reciprocator to reward the fair donor only when it had seen the distributive actions performed by the donors. We propose that infants were able to generate evaluations of agents that were based on the fairness of their distributive actions and to generate expectations about the social preferences of informed third parties.

  6. Indirect reciprocity under incomplete observation.

    PubMed

    Nakamura, Mitsuhiro; Masuda, Naoki

    2011-07-01

    Indirect reciprocity, in which individuals help others with a good reputation but not those with a bad reputation, is a mechanism for cooperation in social dilemma situations when individuals do not repeatedly interact with the same partners. In a relatively large society where indirect reciprocity is relevant, individuals may not know each other's reputation even indirectly. Previous studies investigated the situations where individuals playing the game have to determine the action possibly without knowing others' reputations. Nevertheless, the possibility that observers of the game, who generate the reputation of the interacting players, assign reputations without complete information about them has been neglected. Because an individual acts as an interacting player and as an observer on different occasions if indirect reciprocity is endogenously sustained in a society, the incompleteness of information may affect either role. We examine the game of indirect reciprocity when the reputations of players are not necessarily known to observers and to interacting players. We find that the trustful discriminator, which cooperates with good and unknown players and defects against bad players, realizes cooperative societies under seven social norms. Among the seven social norms, three of the four suspicious norms under which cooperation (defection) to unknown players leads to a good (bad) reputation enable cooperation down to a relatively small observation probability. In contrast, the three trustful norms under which both cooperation and defection to unknown players lead to a good reputation are relatively efficient.

  7. Reciprocity theory of homogeneous reactions

    NASA Astrophysics Data System (ADS)

    Agbormbai, Adolf A.

    1990-03-01

    The reciprocity formalism is applied to the homogeneous gaseous reactions in which the structure of the participating molecules changes upon collision with one another, resulting in a change in the composition of the gas. The approach is applied to various classes of dissociation, recombination, rearrangement, ionizing, and photochemical reactions. It is shown that for the principle of reciprocity to be satisfied it is necessary that all chemical reactions exist in complementary pairs which consist of the forward and backward reactions. The backward reaction may be described by either the reverse or inverse process. The forward and backward processes must satisfy the same reciprocity equation. Because the number of dynamical variables is usually unbalanced on both sides of a chemical equation, it is necessary that this balance be established by including as many of the dynamical variables as needed before the reciprocity equation can be formulated. Statistical transformation models of the reactions are formulated. The models are classified under the titles free exchange, restricted exchange and simplified restricted exchange. The special equations for the forward and backward processes are obtained. The models are consistent with the H theorem and Le Chatelier's principle. The models are also formulated in the context of the direct simulation Monte Carlo method.

  8. Reciprocity and Humility in Wonderland

    ERIC Educational Resources Information Center

    Harry, Beth

    2011-01-01

    This article supports the perspective of Jan Valle regarding the importance of recognizing the subjectivity inherent in decisions about Learning Disabilities. The author argues that the perspectives of both parents and professionals are informed by subjective judgments that must be taken into account in decision making. A reciprocal approach to…

  9. Mobile inertial sensor based gait analysis: Validity and reliability of spatiotemporal gait characteristics in healthy seniors.

    PubMed

    Donath, Lars; Faude, Oliver; Lichtenstein, Eric; Pagenstert, Geert; Nüesch, Corina; Mündermann, Annegret

    2016-09-01

    Gait analysis is commonly used to identify gait changes and fall risk in clinical populations and seniors. Body-worn inertial sensor based gait analyses provide a feasible alternative to optometric and pressure based measurements of spatiotemporal gait characteristics. We assessed validity and relative and absolute reliability of a body-worn inertial sensor system (RehaGait(®)) for measuring spatiotemporal gait characteristics compared to a standard stationary treadmill (Zebris(®)). Spatiotemporal gait parameters (walking speed, stride length, cadence and stride time) were collected for 24 healthy seniors (age: 75.3±6.7 years) tested on 2 days (1 week apart) simultaneously using the sensor based system and instrumented treadmill. Each participant completed walking tests (200 strides) at different walking speeds and slopes. The difference between the RehaGait(®) system and the treadmill was trivial (Cohen's d<0.2) except for speed and stride length at slow speed (Cohen's d, 0.35 and 0.49, respectively). Intraclass correlation coefficients (ICC) were excellent for temporal gait characteristics (cadence and stride time; ICC: 0.99-1.00) and moderate for stride length (ICC: 0.73-0.89). Both devices had excellent day-to-day reliability for all gait parameters (ICC: 0.82-0.99) except for stride length at slow speed (ICC: 0.74). The RehaGait(®) is a valid and reliable tool for assessing spatiotemporal gait parameters for treadmill walking at different speeds and slopes. PMID:27494305

  10. The Pathomechanics Of Calcaneal Gait

    NASA Astrophysics Data System (ADS)

    Sutherland, David H.; Cooper, Les

    1980-07-01

    The data acquisition system employed in our laboratory includes optical, electronic and computer subsystems. Three movie camera freeze the motion for analysis. The film is displayed on a motion analyzer, and the body segment positions are recorded in a three dimensional coordinate system with Graf/pen sonic digitizer. The angular rotations are calculated by computer and automatically plotted. The force plate provides measurements of vertical force, foreaft shear, medial-lateral shear, torque, and center of pressure. Electromyograms are superimposed upon gait movies to permit measurement of muscle phasic activity. The Hycam movie camera si-multaneously films (through separate lens) the subject and oscilloscope. Movement measurements, electromyograms, and floor reaction forces provide the data base for analysis. From a study of the gait changes in five normal subjects following tibial nerve block, and from additional studies of patients with paralysis of the ankle plantar flexors, the pathomechanics of calcaneal gait can be described. Inability to transfer weight to the forward part of the foot produces ankle instability and reduction of contralateral step length. Excessive drop of the center of mass necessitates com-pensatory increased lift energy output through the sound limb to restore the height of the center of mass. Excessive stance phase ankle dorsiflexion produces knee instability requiring prolonged quadriceps muscle phasic activity.

  11. Segmentation and classification of gait cycles.

    PubMed

    Agostini, Valentina; Balestra, Gabriella; Knaflitz, Marco

    2014-09-01

    Gait abnormalities can be studied by means of instrumented gait analysis. Foot-switches are useful to study the foot-floor contact and for timing the gait phases in many gait disorders, provided that a reliable foot-switch signal may be collected. Considering long walks allows reducing the intra-subject variability, but requires automatic and user-independent methods to analyze a large number of gait cycles. The aim of this work is to describe and validate an algorithm for the segmentation of the foot-switch signal and the classification of the gait cycles. The performance of the algorithm was assessed comparing its results against the manual segmentation and classification performed by a gait analysis expert on the same signal. The performance was found to be equal to 100% for healthy subjects and over 98% for pathological subjects. The algorithm allows determining the atypical cycles (cycles that do not match the standard sequence of gait phases) for many different kinds of pathological gait, since it is not based on pathology-specific templates.

  12. Optics in gait analysis and anthropometry

    NASA Astrophysics Data System (ADS)

    Silva Moreno, Alejandra Alicia

    2013-11-01

    Since antiquity, human gait has been studied to understand human movement, the kind of gait, in some cases, can cause musculoskeletal disorders or other health problems; in addition, also from antiquity, anthropometry has been important for the design of human items such as workspaces, tools, garments, among others. Nowadays, thanks to the development of optics and electronics, more accurate studies of gait and anthropometry can be developed. This work will describe the most important parameters for gait analysis, anthropometry and the optical systems used.

  13. Mixed gaits in small avian terrestrial locomotion

    PubMed Central

    Andrada, Emanuel; Haase, Daniel; Sutedja, Yefta; Nyakatura, John A.; M. Kilbourne, Brandon; Denzler, Joachim; Fischer, Martin S.; Blickhan, Reinhard

    2015-01-01

    Scientists have historically categorized gaits discretely (e.g. regular gaits such as walking, running). However, previous results suggest that animals such as birds might mix or regularly or stochastically switch between gaits while maintaining a steady locomotor speed. Here, we combined a novel and completely automated large-scale study (over one million frames) on motions of the center of mass in several bird species (quail, oystercatcher, northern lapwing, pigeon, and avocet) with numerical simulations. The birds studied do not strictly prefer walking mechanics at lower speeds or running mechanics at higher speeds. Moreover, our results clearly display that the birds in our study employ mixed gaits (such as one step walking followed by one step using running mechanics) more often than walking and, surprisingly, maybe as often as grounded running. Using a bio-inspired model based on parameters obtained from real quails, we found two types of stable mixed gaits. In the first, both legs exhibit different gait mechanics, whereas in the second, legs gradually alternate from one gait mechanics into the other. Interestingly, mixed gaits parameters mostly overlap those of grounded running. Thus, perturbations or changes in the state induce a switch from grounded running to mixed gaits or vice versa. PMID:26333477

  14. Dopaminergic and non-dopaminergic pharmacological hypotheses for gait disorders in Parkinson's disease.

    PubMed

    Devos, David; Defebvre, L; Bordet, R

    2010-08-01

    Gait disorders form one component of the axial disorders observed in Parkinson's disease (PD). Indeed, short steps with a forward-leaning stance are diagnostic criteria for PD in the early stages of the condition. Gait disorders also represent a major source of therapeutic failure in the advanced stages of PD (with the appearance of freezing of gait and falls) because they do not respond optimally to the two hand late-stage therapeutics--levodopa and electrical subthalamic nucleus (STN) stimulation. The late onset of doparesistance in these disorders may be linked to propagation of neurodegeneration to structures directly involved in gait control and to non-dopaminergic neurotransmitter systems. The coeruleus locus (a source of noradrenaline) is rapidly and severely affected, leading to a major motor impact. The pedunculopontine nucleus (PPN) and lateral pontine tegmentum (rich in acetylcholine) are both involved in gait. Degenerative damage to the serotoninergic raphe nuclei appears to be less severe, although serotonin-dopamine interactions are numerous and complex. Lastly, dopaminergic depletion leads to glutamatergic hyperactivity of the efferent pathways from the the STN to the PPN. However, the relationships between the various parkinsonian symptoms (and particularly gait disorders) and these pharmacological targets have yet to be fully elucidated. The goal of this review is to develop the various pathophysiological hypotheses published to date, in order to underpin and justify ongoing fundamental research and clinical trials in this disease area.

  15. Gait restoration in paraplegic patients: a feasibility demonstration using multichannel surface electrode FES.

    PubMed

    Kralj, A; Bajd, T; Turk, R; Krajnik, J; Benko, H

    1983-07-01

    Recent advances in science have aided research toward the restoration of biped gait in paraplegic patients by means of functional electrical stimulation (FES). In this paper it is shown how FES-restrengthened muscles of paraplegic patients have been used for simple FES-assisted standing. Those experiments subsequently led to biped gait-initializing experiments and to simple forms of biped gait synthesis. The purpose of this paper is to show the feasibility of using FES for standing and for restoring biped gait in many paraplegic patients--to present the past achievements, focus on problems, and highlight directions for future research. The results of gait obtained in three complete spinal cord injured patients (out of a series of 17) are shown, using four to six channels of FES. It is also shown how preserved reflex mechanisms of the transected spinal cord can be incorporated and employed for obtaining improved function while at the same time simplifying the FES hardware. Of the three patients reported on in detail here, two patients have managed to walk in parallel bars while the third patient has mastered independent unassisted walking over shorter distances with the aid of a roller walker. The biomechanical and control problems of this last patient's gait are presented in detail.

  16. An Inquiry into Relationship Suicides and Reciprocity

    ERIC Educational Resources Information Center

    Davis, Mark S.; Callanan, Valerie J.; Lester, David; Haines, Janet

    2009-01-01

    Few theories on suicide have been grounded in the norm of reciprocity. There is literature on suicide, however, describing motivations such as retaliation and retreat which can be interpreted as modes of adaptation to the norm of reciprocity. We propose a reciprocity-based theory to explain suicides associated with relationship problems. Employing…

  17. 47 CFR 51.221 - Reciprocal compensation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Reciprocal compensation. 51.221 Section 51.221... Obligations of All Local Exchange Carriers § 51.221 Reciprocal compensation. The rules governing reciprocal compensation are set forth in subpart H of this part....

  18. Capuchin Monkeys Judge Third-Party Reciprocity

    ERIC Educational Resources Information Center

    Anderson, James R.; Takimoto, Ayaka; Kuroshima, Hika; Fujita, Kazuo

    2013-01-01

    Increasing interest is being shown in how children develop an understanding of reciprocity in social exchanges and fairness in resource distribution, including social exchanges between third parties. Although there are descriptions of reciprocity on a one-to-one basis in other species, whether nonhumans detect reciprocity and violations of…

  19. Application of the Gillette Gait Index, Gait Deviation Index and Gait Profile Score to multiple clinical pediatric populations.

    PubMed

    McMulkin, Mark L; MacWilliams, Bruce A

    2015-02-01

    Gait indices are now commonly used to assess overall pathology and outcomes from studies with instrumented gait analyses. There are differences in how these indices are calculated and therefore inherent differences in their sensitivities to detect changes or differences between groups. The purpose of the current study was to examine the three most commonly used gait indices, Gillette Gait Index (GGI), Gait Deviation Index (GDI), and Gait Profile Score (GPS), comparing the statistical sensitivity and the ability to make meaningful interpretations of the clinical results. In addition, the GDI*, a log transformed and scaled version of the GPS score which closely matches the GDI was examined. For seven previous or ongoing studies representing varying gait pathologies seen in clinical laboratories, the GGI, GDI, and GPS/GDI* were calculated retrospectively. The GDI and GPS/GDI* proved to be the most sensitive measures in assessing differences pre/post-treatment or from a control population. A power analysis revealed the GDI and GDI* to be the most sensitive statistical measures (lowest sample sizes required). Subjectively, the GDI and GDI* interpretation seemed to be the most intuitive measure for assessing clinical changes. However, the gait variable sub-scores of the GPS determined several statistical differences which were not previously noted and was the only index tool for quantifying the relative contributions of specific joints or planes of motion. The GGI did not offer any advantages over the other two indices.

  20. Developing a portable gait cycle detection system using an inertial sensor and evaluating the accuracy of the gait cycle detection.

    PubMed

    Park, Min-Hwa; Kwak, Ki-Young; Kim, Dong-Wook

    2015-01-01

    Although researches had analyzed gait using small sensors, they analyzed only normal gaits. Thus, a research that can overcome the spatial limitations of the existing motion analyses and diagnose abnormal gaits for medical treatment is needed. Accordingly, this research developed the portable gait detection system that can detect gait using a gyroscope, and evaluated the accuracy of the system. The results showed an average recognition error rate of 1.7% for the normal and abnormal gaits, and confirmed that the gait cycle was detected with a high degree of accuracy. Using these characteristics, we could distinguish or diagnose, and treat, an abnormal gait.

  1. Cognition and Gait Show a Selective Pattern of Association Dominated by Phenotype in Incident Parkinson’s Disease

    PubMed Central

    Lord, Sue; Galna, Brook; Coleman, Shirley; Yarnall, Alison; Burn, David; Rochester, Lynn

    2014-01-01

    Reports outlining the association between gait and cognition in Parkinson’s disease (PD) are limited because of methodological issues and a bias toward studying advanced disease. This study examines the association between gait and cognition in 121 early PD who were characterized according to motor phenotype, and 184 healthy older adults. Quantitative gait was captured using a 7 m GAITrite walkway while walking for 2 min under single-task conditions and described by five domains (pace, rhythm, variability, asymmetry, and postural control). Cognitive outcomes were summarized by six domains (attention, working memory, visual memory, executive function, visuospatial function, and global cognition). Partial correlations and multivariate linear regression were used to determine independent associations for all participants and for PD tremor-dominant (TD) and postural instability and gait disorder (PIGD) phenotypes, controlling for age, sex, and premorbid intelligence using the national adult reading test. Cognitive and gait outcomes were significantly worse for PD. Gait, but not cognitive outcomes, was selectively worse for the PIGD phenotype compared with TD. Significant associations emerged for two gait domains for controls (pace and postural control) and four gait domains for PD (pace, rhythm, variability, and postural control). The strongest correlation was for pace and attention for PD and controls. Associations were not significant for participants with the TD phenotype. In early PD, the cognitive correlates of gait are predominantly with fronto-executive functions, and are characterized by the PIGD PD phenotype. These associations provide a basis for understanding the complex role of cognition in parkinsonian gait. PMID:25374538

  2. Comparison of Upright Gait with Supine Bungee-Cord Gait

    NASA Technical Reports Server (NTRS)

    Boda, Wanda L.; Hargens, Alan R.; Campbell, J. A.; Yang, C.; Holton, Emily M. (Technical Monitor)

    1998-01-01

    Running on a treadmill with bungee-cord resistance is currently used on the Russian space station MIR as a countermeasure for the loss of bone and muscular strength which occurs during spaceflight. However, it is unknown whether ground reaction force (GRF) at the feet using bungee-cord resistance is similar to that which occurs during upright walking and running on Earth. We hypothesized-that the DRAMs generated during upright walking and running are greater than the DRAMs generated during supine bungee-cord gait. Eleven healthy subjects walked (4.8 +/- 0.13 km/h, mean +/- SE) and ran (9.1 +/- 0.51 km/h) during upright and supine bungee-cord exercise on an active treadmill. Subjects exercised for 3 min in each condition using a resistance of 1 body weight calibrated during an initial, stationary standing position. Data were sampled at a frequency of 500Hz and the mean of 3 trials was analyzed for each condition. A repeated measures analysis of variance tested significance between the conditions. Peak DRAMs during upright walking were significantly greater (1084.9 +/- 111.4 N) than during supine bungee-cord walking (770.3 +/- 59.8 N; p less than 0.05). Peak GRFs were also significantly greater for upright running (1548.3 +/- 135.4 N) than for supine bungee-cord running (1099.5 +/- 158.46 N). Analysis of GRF curves indicated that forces decreased throughout the stance phase for bungee-cord gait but not during upright gait. These results indicate that bungee-cord exercise may not create sufficient loads at the feet to counteract the loss of bone and muscular strength that occurs during long-duration exposure to microgravity.

  3. Periodical gait asymmetry assessment using real-time wireless gyroscopes gait monitoring system.

    PubMed

    Gouwanda, D; Senanayake, S M N A

    2011-11-01

    A real-time gait monitoring system that incorporates an immediate and periodical assessment of gait asymmetry is described. This system was designed for gait analysis and rehabilitation of patients with pathologic gait. It employs wireless gyroscopes to measure the angular rate of the thigh and shank in real time. Cross-correlation of the lower extremity (Cc(norm)), and normalized Symmetry Index (SI(norm)) are implemented as new approaches to periodically determine the gait asymmetry in each gait cycle. Cc(norm) evaluates the signal patterns measured by wireless gyroscopes in each gait cycle. SI(norm) determines the movement differences between the left and right limb. An experimental study was conducted to examine the viability of these methods. Artificial asymmetrical gait was simulated by placing a load on one side of the limbs. Results showed that there were significant differences between the normal gait and asymmetrical gait (p < 0.01). They also indicated that the system worked well in periodically assessing the gait asymmetry.

  4. A gait index may underestimate changes of gait: a comparison of the Movement Deviation Profile and the Gait Deviation Index.

    PubMed

    Barton, Gabor J; Hawken, Malcolm B; Holmes, Gill; Schwartz, Michael H

    2015-01-01

    The ability of the Movement Deviation Profile (MDP) and Gait Deviation Index (GDI) to detect gait changes was compared in a child with cerebral palsy who underwent game training. Conventional gait analysis showed that sagittal plane angles became mirrored about normality after training. Despite considerable gait changes, the GDI showed minimal change, while the MDP detected a difference equal to a shift between 10-9 on the Functional Assessment Questionnaire scale. Responses of the GDI and MDP were examined during a synthetic transition of the patient's curves from before intervention to a state mirrored about normality. The GDI showed a symmetric response on the two opposite sides of normality but the neural network based MDP gave an asymmetric response reflecting faithfully the unequal biomechanical consequences of joint angle changes. In conclusion, the MDP can detect altered gait even if the changes are missed by the GDI. PMID:23521124

  5. A gait index may underestimate changes of gait: a comparison of the Movement Deviation Profile and the Gait Deviation Index.

    PubMed

    Barton, Gabor J; Hawken, Malcolm B; Holmes, Gill; Schwartz, Michael H

    2015-01-01

    The ability of the Movement Deviation Profile (MDP) and Gait Deviation Index (GDI) to detect gait changes was compared in a child with cerebral palsy who underwent game training. Conventional gait analysis showed that sagittal plane angles became mirrored about normality after training. Despite considerable gait changes, the GDI showed minimal change, while the MDP detected a difference equal to a shift between 10-9 on the Functional Assessment Questionnaire scale. Responses of the GDI and MDP were examined during a synthetic transition of the patient's curves from before intervention to a state mirrored about normality. The GDI showed a symmetric response on the two opposite sides of normality but the neural network based MDP gave an asymmetric response reflecting faithfully the unequal biomechanical consequences of joint angle changes. In conclusion, the MDP can detect altered gait even if the changes are missed by the GDI.

  6. Variability and similarity of gait as evaluated by joint angles: implications for forensic gait analysis.

    PubMed

    Yang, Sylvia X M; Larsen, Peter K; Alkjær, Tine; Simonsen, Erik B; Lynnerup, Niels

    2014-03-01

    Closed-circuit television (CCTV) footage is used in criminal investigations to compare perpetrators with suspects. Usually, incomplete gait cycles are collected, making evidential gait analysis challenging. This study aimed to analyze the discriminatory power of joint angles throughout a gait cycle. Six sets from 12 men were collected. For each man, a variability range VR (mean ± 1SD) of a specific joint angle at a specific time point (a gait cycle was 100 time points) was calculated. In turn, each individual was compared with the 11 others, and whenever 1 of these 11 had a value within this individual’s VR, it counted as positive. By adding the positives throughout the gait cycle, we created simple bar graphs; tall bars indicated a small discriminatory power, short bars indicated a larger one. The highest discriminatory power was at time points 60–80 in the gait cycle. We show how our data can assess gait data from an actual case.

  7. Reciprocal food sharing in the vampire bat

    NASA Astrophysics Data System (ADS)

    Wilkinson, Gerald S.

    1984-03-01

    Behavioural reciprocity can be evolutionarily stable1-3. Initial increase in frequency depends, however, on reciprocal altruists interacting predominantly with other reciprocal altruists either by associating within kin groups or by having sufficient memory to recognize and not aid nonreciprocators. Theory thus suggests that reciprocity should evolve more easily among animals which live in kin groups. Data are available separating reciprocity from nepotism only for unrelated nonhuman animals4. Here, I show that food sharing by regurgitation of blood among wild vampire bats (Desmodus rotundus) depends equally and independently on degree of relatedness and an index of opportunity for recipro cation. That reciprocity operates within groups containing both kin and nonkin is supported further with data on the availability of blood-sharing occasions, estimates of the economics of shar ing blood, and experiments which show that unrelated bats will reciprocally exchange blood in captivity.

  8. Reciprocal uniparental disomy in yeast

    PubMed Central

    Andersen, Sabrina L.; Petes, Thomas D.

    2012-01-01

    In the diploid cells of most organisms, including humans, each chromosome is usually distinguishable from its partner homolog by multiple single-nucleotide polymorphisms. One common type of genetic alteration observed in tumor cells is uniparental disomy (UPD), in which a pair of homologous chromosomes are derived from a single parent, resulting in loss of heterozygosity for all single-nucleotide polymorphisms while maintaining diploidy. Somatic UPD events are usually explained as reflecting two consecutive nondisjunction events. Here we report a previously undescribed mode of chromosome segregation in Saccharomyces cerevisiae in which one cell division produces daughter cells with reciprocal UPD for the same pair of chromosomes without an aneuploid intermediate. One pair of sister chromatids is segregated into one daughter cell and the other pair is segregated into the other daughter cell, mimicking a meiotic chromosome segregation pattern. We term this process “reciprocal uniparental disomy.” PMID:22665764

  9. An Autonomously Reciprocating Transmembrane Nanoactuator.

    PubMed

    Watson, Matthew A; Cockroft, Scott L

    2016-01-22

    Biological molecular machines operate far from equilibrium by coupling chemical potential to repeated cycles of dissipative nanomechanical motion. This principle has been exploited in supramolecular systems that exhibit true machine behavior in solution and on surfaces. However, designed membrane-spanning assemblies developed to date have been limited to simple switches or stochastic shuttles, and true machine behavior has remained elusive. Herein, we present a transmembrane nanoactuator that turns over chemical fuel to drive autonomous reciprocating (back-and-forth) nanomechanical motion. Ratcheted reciprocating motion of a DNA/PEG copolymer threaded through a single α-hemolysin pore was induced by a combination of DNA strand displacement processes and enzyme-catalyzed reactions. Ion-current recordings revealed saw-tooth patterns, indicating that the assemblies operated in autonomous, asymmetric cycles of conformational change at rates of up to one cycle per minute. PMID:26661295

  10. Piston reciprocating compressed air engine

    SciTech Connect

    Cestero, L.G.

    1987-03-24

    A compressed air engine is described comprising: (a). a reservoir of compressed air, (b). two power cylinders each containing a reciprocating piston connected to a crankshaft and flywheel, (c). a transfer cylinder which communicates with each power cylinder and the reservoir, and contains a reciprocating piston connected to the crankshaft, (d). valve means controlled by rotation of the crankshaft for supplying compressed air from the reservoir to each power cylinder and for exhausting compressed air from each power cylinder to the transfer cylinder, (e). valve means controlled by rotation of the crankshaft for supplying from the transfer cylinder to the reservoir compressed air supplied to the transfer cylinder on the exhaust strokes of the pistons of the power cylinders, and (f). an externally powered fan for assisting the exhaust of compressed air from each power cylinder to the transfer cylinder and from there to the compressed air reservoir.

  11. Gait Analysis by High School Students

    ERIC Educational Resources Information Center

    Heck, Andre; van Dongen, Caroline

    2008-01-01

    Human walking is a complicated motion. Movement scientists have developed various research methods to study gait. This article describes how a high school student collected and analysed high quality gait data in much the same way that movement scientists do, via the recording and measurement of motions with a video analysis tool and via…

  12. Best compression: Reciprocating or rotary?

    SciTech Connect

    Cahill, C.

    1997-07-01

    A compressor is a device used to increase the pressure of a compressible fluid. The inlet pressure can vary from a deep vacuum to a high positive pressure. The discharge pressure can range from subatmospheric levels to tens of thousands of pounds per square inch. Compressors come in numerous forms, but for oilfield applications there are two primary types, reciprocating and rotary. Both reciprocating and rotary compressors are grouped in the intermittent mode of compression. Intermittent is cyclic in nature, in that a specific quantity of gas is ingested by the compressor, acted upon and discharged before the cycle is repeated. Reciprocating compression is the most common form of compression used for oilfield applications. Rotary screw compressors have a long history but are relative newcomers to oilfield applications. The rotary screw compressor-technically a helical rotor compressor-dates back to 1878. That was when the first rotary screw was manufactured for the purpose of compressing air. Today thousands of rotary screw compression packages are being used throughout the world to compress natural gas.

  13. Evolution of cooperation without reciprocity

    NASA Astrophysics Data System (ADS)

    Riolo, Rick L.; Cohen, Michael D.; Axelrod, Robert

    2001-11-01

    A long-standing problem in biological and social sciences is to understand the conditions required for the emergence and maintenance of cooperation in evolving populations. For many situations, kin selection is an adequate explanation, although kin-recognition may still be a problem. Explanations of cooperation between non-kin include continuing interactions that provide a shadow of the future (that is, the expectation of an ongoing relationship) that can sustain reciprocity, possibly supported by mechanisms to bias interactions such as embedding the agents in a two-dimensional space or other context-preserving networks. Another explanation, indirect reciprocity, applies when benevolence to one agent increases the chance of receiving help from others. Here we use computer simulations to show that cooperation can arise when agents donate to others who are sufficiently similar to themselves in some arbitrary characteristic. Such a characteristic, or `tag', can be a marking, display, or other observable trait. Tag-based donation can lead to the emergence of cooperation among agents who have only rudimentary ability to detect environmental signals and, unlike models of direct or indirect reciprocity, no memory of past encounters is required.

  14. Reciprocating Feed System Development Status

    NASA Technical Reports Server (NTRS)

    Trewek, Mary (Technical Monitor); Blackmon, James B.; Eddleman, David E.

    2005-01-01

    The reciprocating feed system (RFS) is an alternative means of providing high pressure propellant flow at low cost and system mass, with high fail-operational reliability. The RFS functions by storing the liquid propellants in large, low-pressure tanks and then expelling each propellant through two or three small, high-pressure tanks. Each RFS tank is sequentially filled, pressurized, expelled, vented, and refilled so as to provide a constant, or variable, mass flow rate to the engine. This type of system is much lighter than a conventional pressure fed system in part due to the greatly reduced amount of inert tank weight. The delivered payload for an RFS is superior to that of conventional pressure fed systems for conditions of high total impulse and it is competitive with turbopump systems, up to approximately 2000 psi. An advanced version of the RFS uses autogenous pressurization and thrust augmentation to achieve higher performance. In this version, the pressurization gases are combusted in a small engine, thus making the pressurization system, in effect, part of the propulsion system. The RFS appears to be much less expensive than a turbopump system, due to reduced research and development cost and hardware cost, since it is basically composed of small high- pressure tanks, a pressurization system, and control valves. A major benefit is the high reliability fail-operational mode; in the event of a failure in one of the three tank-systems, it can operate on the two remaining tanks. Other benefits include variable pressure and flow rates, ease of engine restart in micro-gravity, and enhanced propellant acquisition and control under adverse acceleration conditions. We present a system mass analysis tool that accepts user inputs for various design and mission parameters and calculates such output values payload and vehicle weights for the conventional pressure fed system, the RFS, the Autogenous Pressurization Thrust Augmentation (APTA) RFS, and turbopump systems

  15. Average Gait Differential Image Based Human Recognition

    PubMed Central

    Chen, Jinyan; Liu, Jiansheng

    2014-01-01

    The difference between adjacent frames of human walking contains useful information for human gait identification. Based on the previous idea a silhouettes difference based human gait recognition method named as average gait differential image (AGDI) is proposed in this paper. The AGDI is generated by the accumulation of the silhouettes difference between adjacent frames. The advantage of this method lies in that as a feature image it can preserve both the kinetic and static information of walking. Comparing to gait energy image (GEI), AGDI is more fit to representation the variation of silhouettes during walking. Two-dimensional principal component analysis (2DPCA) is used to extract features from the AGDI. Experiments on CASIA dataset show that AGDI has better identification and verification performance than GEI. Comparing to PCA, 2DPCA is a more efficient and less memory storage consumption feature extraction method in gait based recognition. PMID:24895648

  16. Coaction versus reciprocity in continuous-time models of cooperation.

    PubMed

    van Doorn, G Sander; Riebli, Thomas; Taborsky, Michael

    2014-09-01

    Cooperating animals frequently show closely coordinated behaviours organized by a continuous flow of information between interacting partners. Such real-time coaction is not captured by the iterated prisoner's dilemma and other discrete-time reciprocal cooperation games, which inherently feature a delay in information exchange. Here, we study the evolution of cooperation when individuals can dynamically respond to each other's actions. We develop continuous-time analogues of iterated-game models and describe their dynamics in terms of two variables, the propensity of individuals to initiate cooperation (altruism) and their tendency to mirror their partner's actions (coordination). These components of cooperation stabilize at an evolutionary equilibrium or show oscillations, depending on the chosen payoff parameters. Unlike reciprocal altruism, cooperation by coaction does not require that those willing to initiate cooperation pay in advance for uncertain future benefits. Correspondingly, we show that introducing a delay to information transfer between players is equivalent to increasing the cost of cooperation. Cooperative coaction can therefore evolve much more easily than reciprocal cooperation. When delays entirely prevent coordination, we recover results from the discrete-time alternating prisoner's dilemma, indicating that coaction and reciprocity are connected by a continuum of opportunities for real-time information exchange.

  17. Characterization of gait pattern by 3D angular accelerations in hemiparetic and healthy gait.

    PubMed

    Rueterbories, Jan; Spaich, Erika G; Andersen, Ole K

    2013-02-01

    Characterization of gait pattern is of interest for clinical gait assessment. Past developments of ambulatory measurement systems have still limitations for daily usage in the clinical environment. This study investigated the potential of 3D angular accelerations of foot, shank, and thigh to characterize gait events and phases of ten healthy and ten hemiparetic subjects. The key feature of the system was the use of angular accelerations obtained by differential measurement. Further, the effect of sensor position and walking cadence on the signal was investigated. We found that gait phases are characterized as modulated amplitudes of angular accelerations of foot, shank, and thigh. Increasing the gait cadence from 70 steps/min to 100 steps/min caused an amplitude increase of the magnitude of the vector, summing all 3D angular accelerations on the sensor position (p<0.001). Comparison of healthy and hemiparetic gait showed a lower mean of the magnitude of the vector during the loading response in the hemiparetic gait (p<0.05), while during pre-swing and swing no significant differences between healthy and hemiparetic gait were observed. A comparison of the tangential acceleration component in the frontal plane showed no statistically significant difference between healthy and hemiparetic gait. Further, no statistically significant difference between the tangential components was found for both groups. This method demonstrated promising results for a possible use for gait assessment.

  18. Imperfect information facilitates the evolution of reciprocity.

    PubMed

    Kurokawa, Shun

    2016-06-01

    The existence of cooperation demands explanation since cooperation is costly to the actor. Reciprocity has long been regarded as a potential explanatory mechanism for the existence of cooperation. Reciprocity is a mechanism wherein a cooperator responds to an opponent's behavior by switching his/her own behavior. Hence, a possible problematic case relevant to the theory of reciprocity evolution arises when the mechanism is such that the information regarding an opponent's behavior is imperfect. Although it has been confirmed also by previous theoretical studies that imperfect information interferes with the evolution of reciprocity, this argument is based on the assumption that there are no mistakes in behavior. And, a previous study presumed that it might be expected that when such mistakes occur, reciprocity can more readily evolve in the case of imperfect information than in the case of perfect information. The reason why the previous study considers so is that in the former case, reciprocators can miss defections incurred by other reciprocators' mistakes due to imperfect information, allowing cooperation to persist when such reciprocators meet. However, contrary to this expectation, the previous study has shown that even when mistakes occur, imperfect information interferes with the evolution of reciprocity. Nevertheless, the previous study assumed that payoffs are linear (i.e., that the effect of behavior is additive and there are no synergetic effects). In this study, we revisited the same problem but removed the assumption that payoffs are linear. We used evolutionarily stable strategy analysis to compare the condition for reciprocity to evolve when mistakes occur and information is imperfect with the condition for reciprocity to evolve when mistakes occur and information is perfect. Our study revealed that when payoffs are not linear, imperfect information can facilitate the evolution of reciprocity when mistakes occur; while when payoffs are linear

  19. Gait transitions in simulated reduced gravity.

    PubMed

    Ivanenko, Yuri P; Labini, Francesca Sylos; Cappellini, Germana; Macellari, Velio; McIntyre, Joseph; Lacquaniti, Francesco

    2011-03-01

    Gravity has a strong effect on gait and the speed of gait transitions. A gait has been defined as a pattern of locomotion that changes discontinuously at the transition to another gait. On Earth, during gradual speed changes, humans exhibit a sudden discontinuous switch from walking to running at a specific speed. To study the effects of altered gravity on both the stance and swing legs, we developed a novel unloading exoskeleton that allows a person to step in simulated reduced gravity by tilting the body relative to the vertical. Using different simulation techniques, we confirmed that at lower gravity levels the transition speed is slower (in accordance with the previously reported Froude number ∼0.5). Surprisingly, however, we found that at lower levels of simulated gravity the transition between walking and running was generally gradual, without any noticeable abrupt change in gait parameters. This was associated with a significant prolongation of the swing phase, whose duration became virtually equal to that of stance in the vicinity of the walk-run transition speed, and with a gradual shift from inverted-pendulum gait (walking) to bouncing gait (running).

  20. Gait patterns in COPD: the Rotterdam Study.

    PubMed

    Lahousse, Lies; Verlinden, Vincentius J A; van der Geest, Jos N; Joos, Guy F; Hofman, Albert; Stricker, Bruno H C; Brusselle, Guy G; Ikram, M Arfan

    2015-07-01

    Gait disturbances in patients with chronic obstructive pulmonary disease (COPD) may lead to disability and falls. As studies assessing gait kinematics in COPD are sparse, we investigated associations of COPD with various gait domains and explored a potential link with falling. Gait was measured within the prospective, population-based Rotterdam Study (age ≥55 years) using an electronic walkway and summarised into seven gait domains: Rhythm, Variability, Phases, Pace, Tandem, Turning and Base of Support. Rhythm is a temporal gait aspect that includes cadence and reflects how quickly steps are taken. Persons with COPD (n=196) exhibited worse Rhythm (-0.21 SD, 95% CI -0.36- -0.06 SD) compared with persons with normal lung function (n=898), independent of age, sex, height, education, smoking or analgesic use, especially when dyspnoea and severe airflow limitation or frequent exacerbations (Global Initiative for Chronic Obstructive Lung Disease group D: -0.83 SD, 95% CI -1.25- -0.41 SD) were present. A lower forced expiratory volume in 1 s was associated with worse Rhythm and Pace, including lower cadence and gait velocity, respectively. Importantly, fallers with COPD had significantly worse Rhythm than nonfallers with COPD. This study demonstrates that persons with COPD exhibit worse Rhythm, especially fallers with COPD. The degree of Rhythm deterioration was associated with the degree of airflow limitation, symptoms and frequency of exacerbations.

  1. Motion cue analysis for parkinsonian gait recognition.

    PubMed

    Khan, Taha; Westin, Jerker; Dougherty, Mark

    2013-01-01

    This paper presents a computer-vision based marker-free method for gait-impairment detection in Patients with Parkinson's disease (PWP). The system is based upon the idea that a normal human body attains equilibrium during the gait by aligning the body posture with Axis-of-Gravity (AOG) using feet as the base of support. In contrast, PWP appear to be falling forward as they are less-able to align their body with AOG due to rigid muscular tone. A normal gait exhibits periodic stride-cycles with stride-angle around 45o between the legs, whereas PWP walk with shortened stride-angle with high variability between the stride-cycles. In order to analyze Parkinsonian-gait (PG), subjects were videotaped with several gait-cycles. The subject's body was segmented using a color-segmentation method to form a silhouette. The silhouette was skeletonized for motion cues extraction. The motion cues analyzed were stride-cycles (based on the cyclic leg motion of skeleton) and posture lean (based on the angle between leaned torso of skeleton and AOG). Cosine similarity between an imaginary perfect gait pattern and the subject gait patterns produced 100% recognition rate of PG for 4 normal-controls and 3 PWP. Results suggested that the method is a promising tool to be used for PG assessment in home-environment. PMID:23407764

  2. Gait variability and disability in multiple sclerosis.

    PubMed

    Socie, Michael J; Motl, Robert W; Pula, John H; Sandroff, Brian M; Sosnoff, Jacob J

    2013-05-01

    Gait variability is clinically relevant in some populations, but there is limited documentation of gait variability in persons with multiple sclerosis (MS). This investigation examined average and variability of spatiotemporal gait parameters in persons with MS and healthy controls and subsequent associations with disability status. 88 individuals with MS (age 52.4±11.1) and 20 healthy controls (age 50.9±8.7) performed two self-paced walking trials on a 7.9-m electronic walkway to determine gait parameters. Disability was indexed by the Expanded Disability Status Scale (EDSS) and ranged between 2.5 and 6.5. Gait variability was indexed by standard deviation (SD) and coefficient of variation (CV=SD/mean) of step time, step length, and step width. Average gait parameters were significantly correlated with EDSS (ρ=0.756-0.609) and were significantly different in individuals with MS compared to controls (p≤0.002). Also, step length (p<0.001) and step time (p<0.001) variability were both significantly greater in MS compared to controls. EDSS was positively correlated with step length variability and individuals with MS who used assistive devices to walk had significantly greater step length variability than those who walked independently (p's<.05). EDSS was correlated with step time and length variability even when age was taken into account. Additionally, Fisher's z test of partial correlations revealed that average gait parameters were more closely related to disability status than gait variability in individuals with MS. This suggests that focusing on average gait parameters may be more important than variability in therapeutic interventions in MS.

  3. Directional excitation without breaking reciprocity

    NASA Astrophysics Data System (ADS)

    Ramezani, Hamidreza; Dubois, Marc; Wang, Yuan; Shen, Y. Ron; Zhang, Xiang

    2016-09-01

    We propose a mechanism for directional excitation without breaking reciprocity. This is achieved by embedding an impedance matched parity-time symmetric potential in a three-port system. The amplitude distribution within the gain and loss regions is strongly influenced by the direction of the incoming field. Consequently, the excitation of the third port is contingent on the direction of incidence while transmission in the main channel is immune. Our design improves the four-port directional coupler scheme, as there is no need to implement an anechoic termination to one of the ports.

  4. Towards a unified theory of reciprocity.

    PubMed

    Rosas, Alejandro

    2012-02-01

    In a unified theory of human reciprocity, the strong and weak forms are similar because neither is biologically altruistic and both require normative motivation to support cooperation. However, strong reciprocity is necessary to support cooperation in public goods games. It involves inflicting costs on defectors; and though the costs for punishers are recouped, recouping costs requires complex institutions that would not have emerged if weak reciprocity had been enough.

  5. Variations in kinematics during clinical gait analysis in stroke patients.

    PubMed

    Boudarham, Julien; Roche, Nicolas; Pradon, Didier; Bonnyaud, Céline; Bensmail, Djamel; Zory, Raphael

    2013-01-01

    In addition to changes in spatio-temporal and kinematic parameters, patients with stroke exhibit fear of falling as well as fatigability during gait. These changes could compromise interpretation of data from gait analysis. The aim of this study was to determine if the gait of hemiplegic patients changes significantly over successive gait trials. Forty two stroke patients and twenty healthy subjects performed 9 gait trials during a gait analysis session. The mean and variability of spatio-temporal and kinematic joint parameters were analyzed during 3 groups of consecutive gait trials (1-3, 4-6 and 7-9). Principal component analysis was used to reduce the number of variables from the joint kinematic waveforms and to identify the parts of the gait cycle which changed during the gait analysis session. The results showed that i) spontaneous gait velocity and the other spatio-temporal parameters significantly increased, and ii) gait variability decreased, over the last 6 gait trials compared to the first 3, for hemiplegic patients but not healthy subjects. Principal component analysis revealed changes in the sagittal waveforms of the hip, knee and ankle for hemiplegic patients after the first 3 gait trials. These results suggest that at the beginning of the gait analysis session, stroke patients exhibited phase of adaptation,characterized by a "cautious gait" but no fatigue was observed.

  6. Reciprocating motion of active deformable particles

    NASA Astrophysics Data System (ADS)

    Tarama, M.; Ohta, T.

    2016-05-01

    Reciprocating motion of an active deformable particle in a homogeneous medium is studied theoretically. For generality, we employ a simple model derived from symmetry considerations for the center-of-mass velocity and elliptical and triangular deformations in two dimensions. We carry out, for the first time, a systematic investigation of the reciprocating motion of a self-propelled particle. It is clarified that spontaneous breaking of the front-rear asymmetry is essential for the reciprocating motion. Moreover, two routes are found for the formation of the reciprocating motion. One is a bifurcation from a motionless stationary state. The other is destabilisation of an oscillatory rectilinear motion.

  7. Evolution of spite through indirect reciprocity.

    PubMed Central

    Johnstone, Rufus A.; Bshary, Redouan

    2004-01-01

    How can cooperation persist in the face of a temptation to 'cheat'? Several recent papers have suggested that the answer may lie in indirect reciprocity. Altruistic individuals may benefit by eliciting altruism from observers, rather than (as in direct reciprocity) from the recipient of the aid they provide. Here, we point out that indirect reciprocity need not always favour cooperation; by contrast, it may support spiteful behaviour, which is costly for the both actor and recipient. Existing theory suggests spite is unlikely to persist, but we demonstrate that it may do so when spiteful individuals are less likely to incur aggression from observers (a negative form of indirect reciprocity). PMID:15347514

  8. Gait recognition based on Gabor wavelets and modified gait energy image for human identification

    NASA Astrophysics Data System (ADS)

    Huang, Deng-Yuan; Lin, Ta-Wei; Hu, Wu-Chih; Cheng, Chih-Hsiang

    2013-10-01

    This paper proposes a method for recognizing human identity using gait features based on Gabor wavelets and modified gait energy images (GEIs). Identity recognition by gait generally involves gait representation, extraction, and classification. In this work, a modified GEI convolved with an ensemble of Gabor wavelets is proposed as a gait feature. Principal component analysis is then used to project the Gabor-wavelet-based gait features into a lower-dimension feature space for subsequent classification. Finally, support vector machine classifiers based on a radial basis function kernel are trained and utilized to recognize human identity. The major contributions of this paper are as follows: (1) the consideration of the shadow effect to yield a more complete segmentation of gait silhouettes; (2) the utilization of motion estimation to track people when walkers overlap; and (3) the derivation of modified GEIs to extract more useful gait information. Extensive performance evaluation shows a great improvement of recognition accuracy due to the use of shadow removal, motion estimation, and gait representation using the modified GEIs and Gabor wavelets.

  9. Indirect reciprocity with trinary reputations.

    PubMed

    Tanabe, Shoma; Suzuki, Hideyuki; Masuda, Naoki

    2013-01-21

    Indirect reciprocity is a reputation-based mechanism for cooperation in social dilemma situations when individuals do not repeatedly meet. The conditions under which cooperation based on indirect reciprocity occurs have been examined in great details. Most previous theoretical analysis assumed for mathematical tractability that an individual possesses a binary reputation value, i.e., good or bad, which depends on their past actions and other factors. However, in real situations, reputations of individuals may be multiple valued. Another puzzling discrepancy between the theory and experiments is the status of the so-called image scoring, in which cooperation and defection are judged to be good and bad, respectively, independent of other factors. Such an assessment rule is found in behavioral experiments, whereas it is known to be unstable in theory. In the present study, we fill both gaps by analyzing a trinary reputation model. By an exhaustive search, we identify all the cooperative and stable equilibria composed of a homogeneous population or a heterogeneous population containing two types of players. Some results derived for the trinary reputation model are direct extensions of those for the binary model. However, we find that the trinary model allows cooperation under image scoring under some mild conditions.

  10. Indirect reciprocity with trinary reputations.

    PubMed

    Tanabe, Shoma; Suzuki, Hideyuki; Masuda, Naoki

    2013-01-21

    Indirect reciprocity is a reputation-based mechanism for cooperation in social dilemma situations when individuals do not repeatedly meet. The conditions under which cooperation based on indirect reciprocity occurs have been examined in great details. Most previous theoretical analysis assumed for mathematical tractability that an individual possesses a binary reputation value, i.e., good or bad, which depends on their past actions and other factors. However, in real situations, reputations of individuals may be multiple valued. Another puzzling discrepancy between the theory and experiments is the status of the so-called image scoring, in which cooperation and defection are judged to be good and bad, respectively, independent of other factors. Such an assessment rule is found in behavioral experiments, whereas it is known to be unstable in theory. In the present study, we fill both gaps by analyzing a trinary reputation model. By an exhaustive search, we identify all the cooperative and stable equilibria composed of a homogeneous population or a heterogeneous population containing two types of players. Some results derived for the trinary reputation model are direct extensions of those for the binary model. However, we find that the trinary model allows cooperation under image scoring under some mild conditions. PMID:23123557

  11. Network homophily and the evolution of the pay-it-forward reciprocity.

    PubMed

    Chiang, Yen-Sheng; Takahashi, Nobuyuki

    2011-01-01

    The pay-it-forward reciprocity is a type of cooperative behavior that people who have benefited from others return favors to third parties other than the benefactors, thus pushing forward a cascade of kindness. The phenomenon of the pay-it-forward reciprocity is ubiquitous, yet how it evolves to be part of human sociality has not been fully understood. We develop an evolutionary dynamics model to investigate how network homophily influences the evolution of the pay-it-forward reciprocity. Manipulating the extent to which actors carrying the same behavioral trait are linked in networks, the computer simulation model shows that strong network homophily helps consolidate the adaptive advantage of cooperation, yet introducing some heterophily to the formation of network helps advance cooperation's scale further. Our model enriches the literature of inclusive fitness theory by demonstrating the conditions under which cooperation or reciprocity can be selected for in evolution when social interaction is not confined exclusively to relatives.

  12. Cooperation among non-relatives evolves by state-dependent generalized reciprocity.

    PubMed

    Barta, Zoltán; McNamara, John M; Huszár, Dóra B; Taborsky, Michael

    2011-03-22

    For decades, attempts to understand cooperation between non-kin have generated substantial theoretical and empirical interest in the evolutionary mechanisms of reciprocal altruism. There is growing evidence that the cognitive limitations of animals can hinder direct and indirect reciprocity because the necessary mental capacity is costly. Here, we show that cooperation can evolve by generalized reciprocity (help anyone, if helped by someone) even in large groups, if individuals base their decision to cooperate on a state variable updated by the outcome of the last interaction with an anonymous partner. We demonstrate that this alternative mechanism emerges through small evolutionary steps under a wide range of conditions. Since this state-based generalized reciprocity works without advanced cognitive abilities it may help to understand the evolution of complex social behaviour in a wide range of organisms.

  13. Wearable sensors used for human gait analysis.

    PubMed

    TarniŢă, Daniela

    2016-01-01

    This paper briefly presents recent developments in the field of wearable sensors and systems that are relevant to the area of normal and pathological human gait analysis. By using wearable sensors, it is possible to monitor the pathological gait disorders and alterations and the changes of balance in the people and prevent or diagnose of different diseases. The most usable wearable sensors and their applications in clinical field are presented based on specialty literature.

  14. Toward understanding the limits of gait recognition

    NASA Astrophysics Data System (ADS)

    Liu, Zongyi; Malave, Laura; Osuntogun, Adebola; Sudhakar, Preksha; Sarkar, Sudeep

    2004-08-01

    Most state of the art video-based gait recognition algorithms start from binary silhouettes. These silhouettes, defined as foreground regions, are usually detected by background subtraction methods, which results in holes or missed parts due to similarity of foreground and background color, and boundary errors due to video compression artifacts. Errors in low-level representation make it hard to understand the effect of certain conditions, such as surface and time, on gait recognition. In this paper, we present a part-level, manual silhouette database consisting of 71 subjects, over one gait cycle, with differences in surface, shoe-type, carrying condition, and time. We have a total of about 11,000 manual silhouette frames. The purpose of this manual silhouette database is twofold. First, this is a resource that we make available at http://www.GaitChallenge.org for use by the gait community to test and design better silhouette detection algorithms. These silhouettes can also be used to learn gait dynamics. Second, using the baseline gait recognition algorithm, which was specified along with the HumanID Gait Challenge problem, we show that performance from manual silhouettes is similar and only sometimes better than that from automated silhouettes detected by statistical background subtraction. Low performances when comparing sequences with differences in walking surfaces and time-variation are not fully explained by silhouette quality. We also study the recognition power in each body part and show that recognition based on just the legs is equal to that from the whole silhouette. There is also significant recognition power in the head and torso shape.

  15. Gait Partitioning Methods: A Systematic Review

    PubMed Central

    Taborri, Juri; Palermo, Eduardo; Rossi, Stefano; Cappa, Paolo

    2016-01-01

    In the last years, gait phase partitioning has come to be a challenging research topic due to its impact on several applications related to gait technologies. A variety of sensors can be used to feed algorithms for gait phase partitioning, mainly classifiable as wearable or non-wearable. Among wearable sensors, footswitches or foot pressure insoles are generally considered as the gold standard; however, to overcome some inherent limitations of the former, inertial measurement units have become popular in recent decades. Valuable results have been achieved also though electromyography, electroneurography, and ultrasonic sensors. Non-wearable sensors, such as opto-electronic systems along with force platforms, remain the most accurate system to perform gait analysis in an indoor environment. In the present paper we identify, select, and categorize the available methodologies for gait phase detection, analyzing advantages and disadvantages of each solution. Finally, we comparatively examine the obtainable gait phase granularities, the usable computational methodologies and the optimal sensor placements on the targeted body segments. PMID:26751449

  16. Gait Partitioning Methods: A Systematic Review.

    PubMed

    Taborri, Juri; Palermo, Eduardo; Rossi, Stefano; Cappa, Paolo

    2016-01-01

    In the last years, gait phase partitioning has come to be a challenging research topic due to its impact on several applications related to gait technologies. A variety of sensors can be used to feed algorithms for gait phase partitioning, mainly classifiable as wearable or non-wearable. Among wearable sensors, footswitches or foot pressure insoles are generally considered as the gold standard; however, to overcome some inherent limitations of the former, inertial measurement units have become popular in recent decades. Valuable results have been achieved also though electromyography, electroneurography, and ultrasonic sensors. Non-wearable sensors, such as opto-electronic systems along with force platforms, remain the most accurate system to perform gait analysis in an indoor environment. In the present paper we identify, select, and categorize the available methodologies for gait phase detection, analyzing advantages and disadvantages of each solution. Finally, we comparatively examine the obtainable gait phase granularities, the usable computational methodologies and the optimal sensor placements on the targeted body segments. PMID:26751449

  17. In Vivo Gait Analysis During Bone Transport.

    PubMed

    Mora-Macías, J; Reina-Romo, E; Morgaz, J; Domínguez, J

    2015-09-01

    The load bearing characteristics of the intervened limb over time in vivo are important to know in distraction osteogenesis and bone healing for the characterization of the bone maturation process. Gait analyses were performed for a group of sheep in which bone transport was carried out. The ground reaction force was measured by means of a force platform, and the gait parameters (i.e., the peak, the mean vertical ground reaction force and the impulse) were calculated during the stance phase for each limb. The results showed that these gait parameters decreased in the intervened limb and interestingly increased in the other limbs due to the implantation of the fixator. Additionally, during the process, the gait parameters exponentially approached the values for healthy animals. Corresponding radiographies showed an increasing level of ossification in the callus. This study shows, as a preliminary approach to be confirmed with more experiments, that gait analysis could be used as an alternative method to control distraction osteogenesis or bone healing. For example, these analyses could determine the appropriate time to remove the fixator. Furthermore, gait analysis has advantages over other methods because it provides quantitative data and does not require instrumented fixators.

  18. Gait Recognition Using Wearable Motion Recording Sensors

    NASA Astrophysics Data System (ADS)

    Gafurov, Davrondzhon; Snekkenes, Einar

    2009-12-01

    This paper presents an alternative approach, where gait is collected by the sensors attached to the person's body. Such wearable sensors record motion (e.g. acceleration) of the body parts during walking. The recorded motion signals are then investigated for person recognition purposes. We analyzed acceleration signals from the foot, hip, pocket and arm. Applying various methods, the best EER obtained for foot-, pocket-, arm- and hip- based user authentication were 5%, 7%, 10% and 13%, respectively. Furthermore, we present the results of our analysis on security assessment of gait. Studying gait-based user authentication (in case of hip motion) under three attack scenarios, we revealed that a minimal effort mimicking does not help to improve the acceptance chances of impostors. However, impostors who know their closest person in the database or the genders of the users can be a threat to gait-based authentication. We also provide some new insights toward the uniqueness of gait in case of foot motion. In particular, we revealed the following: a sideway motion of the foot provides the most discrimination, compared to an up-down or forward-backward directions; and different segments of the gait cycle provide different level of discrimination.

  19. The New York Schools Insurance Reciprocal.

    ERIC Educational Resources Information Center

    Lapetina, Alison J.

    1990-01-01

    Describes the New York Schools Insurance Reciprocal (NYSIR), which provides both property and liability coverage for school districts. A reciprocal is wholly owned by those insured. NYSIR insures 55 school district subscribers, providing a service that specifically accommodates school district needs and saves them money. (MLF)

  20. Reciprocal Tutoring: Design with Cognitive Load Sharing

    ERIC Educational Resources Information Center

    Chou, Chih-Yueh; Chan, Tak-Wai

    2016-01-01

    "Reciprocal tutoring," as reported in "Exploring the design of computer supports for reciprocal tutoring" (Chan and Chou 1997), has extended the meaning and scope of "intelligent tutoring" originally implemented in stand alone computers. This research is a follow-up to our studies on a "learning companion…

  1. The Effects of Reciprocal Teaching on Comprehension.

    ERIC Educational Resources Information Center

    Frances, Shannon M.; Eckart, Joyce A.

    An action research project investigated the effect of reciprocal teaching instruction and use on the comprehension of seventh-grade general English students. Reciprocal teaching is a form of dialogue structured around four skills--question generation, summarization, clarification, and prediction. These techniques are used in small group…

  2. Education, Gift and Reciprocity: A Preliminary Discussion

    ERIC Educational Resources Information Center

    Sabourin, Eric

    2013-01-01

    This paper analyzes the importance and role of the reciprocity relationship in education. It presents a review on the mobilization of the principle of reciprocity--in the anthropological but also sociological and economic senses--in educational processes, especially in adult education. The study is divided into three parts. The first part analyzes…

  3. An Introduction to the Onsager Reciprocal Relations

    ERIC Educational Resources Information Center

    Monroe, Charles W.; Newman, John

    2007-01-01

    The Onsager reciprocal relations are essential to multicomponent transport theory. A discussion of the principles that should be used to derive flux laws for coupled diffusion is presented here. Fluctuation theory is employed to determine the reciprocal relation for transport coefficients that characterize coupled mass and heat transfer in binary…

  4. Reflexive and Reciprocal Elements in Ixil.

    ERIC Educational Resources Information Center

    Ayres, Glenn

    1990-01-01

    Reflexives and reciprocals in Ixil, a Mayan language of Guatemala, appear to have features that distinguish them from reflexives surveyed in typological studies such as Faltz (1985) and Geniusiene (1987). Third person reflexives and reciprocals seem to have the form of a possessed noun optionally followed by a possessor NP. Moreover, reflexives…

  5. Powered robotic exoskeletons in post-stroke rehabilitation of gait: a scoping review.

    PubMed

    Louie, Dennis R; Eng, Janice J

    2016-01-01

    Powered robotic exoskeletons are a potential intervention for gait rehabilitation in stroke to enable repetitive walking practice to maximize neural recovery. As this is a relatively new technology for stroke, a scoping review can help guide current research and propose recommendations for advancing the research development. The aim of this scoping review was to map the current literature surrounding the use of robotic exoskeletons for gait rehabilitation in adults post-stroke. Five databases (Pubmed, OVID MEDLINE, CINAHL, Embase, Cochrane Central Register of Clinical Trials) were searched for articles from inception to October 2015. Reference lists of included articles were reviewed to identify additional studies. Articles were included if they utilized a robotic exoskeleton as a gait training intervention for adult stroke survivors and reported walking outcome measures. Of 441 records identified, 11 studies, all published within the last five years, involving 216 participants met the inclusion criteria. The study designs ranged from pre-post clinical studies (n = 7) to controlled trials (n = 4); five of the studies utilized a robotic exoskeleton device unilaterally, while six used a bilateral design. Participants ranged from sub-acute (<7 weeks) to chronic (>6 months) stroke. Training periods ranged from single-session to 8-week interventions. Main walking outcome measures were gait speed, Timed Up and Go, 6-min Walk Test, and the Functional Ambulation Category. Meaningful improvement with exoskeleton-based gait training was more apparent in sub-acute stroke compared to chronic stroke. Two of the four controlled trials showed no greater improvement in any walking outcomes compared to a control group in chronic stroke. In conclusion, clinical trials demonstrate that powered robotic exoskeletons can be used safely as a gait training intervention for stroke. Preliminary findings suggest that exoskeletal gait training is equivalent to traditional therapy

  6. Multiplicative noise enhances spatial reciprocity

    NASA Astrophysics Data System (ADS)

    Yao, Yao; Chen, Shen-Shen

    2014-11-01

    Recent research has identified the heterogeneity as crucial for the evolution of cooperation in spatial population. However, the influence of heterogeneous noise is still lacking. Inspired by this interesting question, in this work, we try to incorporate heterogeneous noise into the evaluation of utility, where only a proportion of population possesses noise, whose range can also be tuned. We find that increasing heterogeneous noise monotonously promotes cooperation and even translates the full defection phase (of the homogeneous version) into the complete cooperation phase. Moreover, the promotion effect of this mechanism can be attributed to the leading role of cooperators who have the heterogeneous noise. These type of cooperators can attract more agents penetrating into the robust cooperator clusters, which is beyond the text of traditional spatial reciprocity. We hope that our work may shed light on the understanding of the cooperative behavior in the society.

  7. Intra-individual gait pattern variability in specific situations: Implications for forensic gait analysis.

    PubMed

    Ludwig, Oliver; Dillinger, Steffen; Marschall, Franz

    2016-07-01

    In this study, inter- and intra-individual gait pattern differences are examined in various gait situations by means of phase diagrams of the extremity angles (cyclograms). 8 test subjects walked along a walking distance of 6m under different conditions three times each: barefoot, wearing sneakers, wearing combat boots, after muscular fatigue, and wearing a full-face motorcycle helmet restricting vision. The joint angles of foot, knee, and hip were recorded in the sagittal plane. The coupling of movements was represented by time-adjusted cyclograms, and the inter- and intra-individual differences were captured by calculating the similarity between different gait patterns. Gait pattern variability was often greater between the defined test situations than between the individual test subjects. The results have been interpreted considering neurophysiological regulation mechanisms. Footwear, masking, and fatigue were interpreted as disturbance parameters, each being a cause for gait pattern variability and complicating the inference of identity of persons in video recordings.

  8. Intra-individual gait pattern variability in specific situations: Implications for forensic gait analysis.

    PubMed

    Ludwig, Oliver; Dillinger, Steffen; Marschall, Franz

    2016-07-01

    In this study, inter- and intra-individual gait pattern differences are examined in various gait situations by means of phase diagrams of the extremity angles (cyclograms). 8 test subjects walked along a walking distance of 6m under different conditions three times each: barefoot, wearing sneakers, wearing combat boots, after muscular fatigue, and wearing a full-face motorcycle helmet restricting vision. The joint angles of foot, knee, and hip were recorded in the sagittal plane. The coupling of movements was represented by time-adjusted cyclograms, and the inter- and intra-individual differences were captured by calculating the similarity between different gait patterns. Gait pattern variability was often greater between the defined test situations than between the individual test subjects. The results have been interpreted considering neurophysiological regulation mechanisms. Footwear, masking, and fatigue were interpreted as disturbance parameters, each being a cause for gait pattern variability and complicating the inference of identity of persons in video recordings. PMID:26990706

  9. Review of hybrid exoskeletons to restore gait following spinal cord injury.

    PubMed

    del-Ama, Antonio J; Koutsou, Aikaterini D; Moreno, Juan C; de-los-Reyes, Ana; Gil-Agudo, Angel; Pons, José L

    2012-01-01

    Different approaches are available to compensate gait in persons with spinal cord injury, including passive orthoses, functional electrical stimulation (FES), and robotic exoskeletons. However, several drawbacks arise from each specific approach. Orthotic gait is energy-demanding for the user and functionally ineffective. FES uses the muscles as natural actuators to generate gait, providing not only functional but also psychological benefits to the users. However, disadvantages are also related to the early appearance of muscle fatigue and the control of joint trajectories. Robotic exoskeletons that provide joint moment compensation or substitution to the body during walking have been developed in recent years. Significant advances have been achieved, but the technology itself is not mature yet because of many limitations related to both physical and cognitive interaction as well as portability and energy-management issues. Meanwhile, the combination of FES technology and exoskeletons has emerged as a promising approach to both gait compensation and rehabilitation, bringing together technologies, methods, and rehabilitation principles that can overcome the drawbacks of each individual approach. This article presents an overview of hybrid lower-limb exoskeletons, related technologies, and advances in actuation and control systems. Also, we highlight the functional assessment of individuals with spinal cord injury.

  10. The impact of vision on the dynamic characteristics of the gait: strategies in children with blindness.

    PubMed

    Gazzellini, Simone; Lispi, Maria Luisa; Castelli, Enrico; Trombetti, Alessandro; Carniel, Sacha; Vasco, Gessica; Napolitano, Antonio; Petrarca, Maurizio

    2016-09-01

    Visually impaired persons present an atypical gait pattern characterized by slower walking speed, shorter stride length and longer time of stance. Three explanatory hypotheses have been advanced in the literature: balance deficit, lack of an anticipatory mechanisms and foot probing the ground. In the present study, we compared the three hypotheses by applying their predictions to gait analysis and posturography of blind children without neurological impairment and compared their performance with that of an age-matched control group. The gait analysis results documented that blind children presented reduced walking velocity and step length, increased step width and external rotation of the foot progression angle, reduced ground reaction force and ankle maximum angle, moment and power in late stance, increased head flexion, decreased thorax flexion and pelvis anteversion, compared with the control group. The posturographic analysis showed equal skill level between blind children and normally sighted children when they close their eyes. The results are consistent with only one of the three hypotheses: namely, they prove that blind children's gait is influenced only by the absence of visually driven anticipatory control mechanisms. Finally, rehabilitative recommendations for children with blindness are advanced in discussion. PMID:27165507

  11. A Validated Smartphone-Based Assessment of Gait and Gait Variability in Parkinson’s Disease

    PubMed Central

    Ellis, Robert J.; Ng, Yee Sien; Zhu, Shenggao; Tan, Dawn M.; Anderson, Boyd; Schlaug, Gottfried; Wang, Ye

    2015-01-01

    Background A well-established connection exists between increased gait variability and greater fall likelihood in Parkinson’s disease (PD); however, a portable, validated means of quantifying gait variability (and testing the efficacy of any intervention) remains lacking. Furthermore, although rhythmic auditory cueing continues to receive attention as a promising gait therapy for PD, its widespread delivery remains bottlenecked. The present paper describes a smartphone-based mobile application (“SmartMOVE”) to address both needs. Methods The accuracy of smartphone-based gait analysis (utilizing the smartphone’s built-in tri-axial accelerometer and gyroscope to calculate successive step times and step lengths) was validated against two heel contact–based measurement devices: heel-mounted footswitch sensors (to capture step times) and an instrumented pressure sensor mat (to capture step lengths). 12 PD patients and 12 age-matched healthy controls walked along a 26-m path during self-paced and metronome-cued conditions, with all three devices recording simultaneously. Results Four outcome measures of gait and gait variability were calculated. Mixed-factorial analysis of variance revealed several instances in which between-group differences (e.g., increased gait variability in PD patients relative to healthy controls) yielded medium-to-large effect sizes (eta-squared values), and cueing-mediated changes (e.g., decreased gait variability when PD patients walked with auditory cues) yielded small-to-medium effect sizes—while at the same time, device-related measurement error yielded small-to-negligible effect sizes. Conclusion These findings highlight specific opportunities for smartphone-based gait analysis to serve as an alternative to conventional gait analysis methods (e.g., footswitch systems or sensor-embedded walkways), particularly when those methods are cost-prohibitive, cumbersome, or inconvenient. PMID:26517720

  12. Dynamic stability and phase resetting during biped gait

    NASA Astrophysics Data System (ADS)

    Nomura, Taishin; Kawa, Kazuyoshi; Suzuki, Yasuyuki; Nakanishi, Masao; Yamasaki, Taiga

    2009-06-01

    Dynamic stability during periodic biped gait in humans and in a humanoid robot is considered. Here gait systems of human neuromusculoskeletal system and a humanoid are simply modeled while keeping their mechanical properties plausible. We prescribe periodic gait trajectories in terms of joint angles of the models as a function of time. The equations of motion of the models are then constrained by one of the prescribed gait trajectories to obtain types of periodically forced nonlinear dynamical systems. Simulated gait of the models may or may not fall down during gait, since the constraints are made only for joint angles of limbs but not for the motion of the body trunk. The equations of motion can exhibit a limit cycle solution (or an oscillatory solution that can be considered as a limit cycle practically) for each selected gait trajectory, if an initial condition is set appropriately. We analyze the stability of the limit cycle in terms of Poincaré maps and the basin of attraction of the limit cycle in order to examine how the stability depends on the prescribed trajectory. Moreover, the phase resetting of gait rhythm in response to external force perturbation is modeled. Since we always prescribe a gait trajectory in this study, reacting gait trajectories during the phase resetting are also prescribed. We show that an optimally prescribed reacting gait trajectory with an appropriate amount of the phase resetting can increase the gait stability. Neural mechanisms for generation and modulation of the gait trajectories are discussed.

  13. Modeling and simulation of normal and hemiparetic gait

    NASA Astrophysics Data System (ADS)

    Luengas, Lely A.; Camargo, Esperanza; Sanchez, Giovanni

    2015-09-01

    Gait is the collective term for the two types of bipedal locomotion, walking and running. This paper is focused on walking. The analysis of human gait is of interest to many different disciplines, including biomechanics, human-movement science, rehabilitation and medicine in general. Here we present a new model that is capable of reproducing the properties of walking, normal and pathological. The aim of this paper is to establish the biomechanical principles that underlie human walking by using Lagrange method. The constraint forces of Rayleigh dissipation function, through which to consider the effect on the tissues in the gait, are included. Depending on the value of the factor present in the Rayleigh dissipation function, both normal and pathological gait can be simulated. First of all, we apply it in the normal gait and then in the permanent hemiparetic gait. Anthropometric data of adult person are used by simulation, and it is possible to use anthropometric data for children but is necessary to consider existing table of anthropometric data. Validation of these models includes simulations of passive dynamic gait that walk on level ground. The dynamic walking approach provides a new perspective of gait analysis, focusing on the kinematics and kinetics of gait. There have been studies and simulations to show normal human gait, but few of them have focused on abnormal, especially hemiparetic gait. Quantitative comparisons of the model predictions with gait measurements show that the model can reproduce the significant characteristics of normal gait.

  14. Gait initiation in children with Rett syndrome.

    PubMed

    Isaias, Ioannis Ugo; Dipaola, Mariangela; Michi, Marlies; Marzegan, Alberto; Volkmann, Jens; Rodocanachi Roidi, Marina L; Frigo, Carlo Albino; Cavallari, Paolo

    2014-01-01

    Rett syndrome is an X-linked neurodevelopmental condition mainly characterized by loss of spoken language and a regression of purposeful hand use, with the development of distinctive hand stereotypies, and gait abnormalities. Gait initiation is the transition from quiet stance to steady-state condition of walking. The associated motor program seems to be centrally mediated and includes preparatory adjustments prior to any apparent voluntary movement of the lower limbs. Anticipatory postural adjustments contribute to postural stability and to create the propulsive forces necessary to reach steady-state gait at a predefined velocity and may be indicative of the effectiveness of the feedforward control of gait. In this study, we examined anticipatory postural adjustments associated with gait initiation in eleven girls with Rett syndrome and ten healthy subjects. Muscle activity (tibialis anterior and soleus muscles), ground reaction forces and body kinematic were recorded. Children with Rett syndrome showed a distinctive impairment in temporal organization of all phases of the anticipatory postural adjustments. The lack of appropriate temporal scaling resulted in a diminished impulse to move forward, documented by an impairment in several parameters describing the efficiency of gait start: length and velocity of the first step, magnitude and orientation of centre of pressure-centre of mass vector at the instant of (swing-)toe off. These findings were related to an abnormal muscular activation pattern mainly characterized by a disruption of the synergistic activity of antagonistic pairs of postural muscles. This study showed that girls with Rett syndrome lack accurate tuning of feedforward control of gait.

  15. Role of Body-Worn Movement Monitor Technology for Balance and Gait Rehabilitation

    PubMed Central

    King, Laurie; Mancini, Martina

    2015-01-01

    This perspective article will discuss the potential role of body-worn movement monitors for balance and gait assessment and treatment in rehabilitation. Recent advances in inexpensive, wireless sensor technology and smart devices are resulting in an explosion of miniature, portable sensors that can quickly and accurately quantify body motion. Practical and useful movement monitoring systems are now becoming available. It is critical that therapists understand the potential advantages and limitations of such emerging technology. One important advantage of obtaining objective measures of balance and gait from body-worn sensors is impairment-level metrics characterizing how and why functional performance of balance and gait activities are impaired. Therapy can then be focused on the specific physiological reasons for difficulty in walking or balancing during specific tasks. A second advantage of using technology to measure balance and gait behavior is the increased sensitivity of the balance and gait measures to document mild disability and change with rehabilitation. A third advantage of measuring movement, such as postural sway and gait characteristics, with body-worn sensors is the opportunity for immediate biofeedback provided to patients that can focus attention and enhance performance. In the future, body-worn sensors may allow therapists to perform telerehabilitation to monitor compliance with home exercise programs and the quality of their natural mobility in the community. Therapists need technological systems that are quick to use and provide actionable information and useful reports for their patients and referring physicians. Therapists should look for systems that provide measures that have been validated with respect to gold standard accuracy and to clinically relevant outcomes such as fall risk and severity of disability. PMID:25504484

  16. Reciprocity and Ethical Tuberculosis Treatment and Control.

    PubMed

    Silva, Diego S; Dawson, Angus; Upshur, Ross E G

    2016-03-01

    This paper explores the notion of reciprocity in the context of active pulmonary and laryngeal tuberculosis (TB) treatment and related control policies and practices. We seek to do three things: First, we sketch the background to contemporary global TB care and suggest that poverty is a key feature when considering the treatment of TB patients. We use two examples from TB care to explore the role of reciprocity: isolation and the use of novel TB drugs. Second, we explore alternative means of justifying the use of reciprocity through appeal to different moral and political theoretical traditions (i.e., virtue ethics, deontology, and consequentialism). We suggest that each theory can be used to provide reasons to take reciprocity seriously as an independent moral concept, despite any other differences. Third, we explore general meanings and uses of the concept of reciprocity, with the primary intention of demonstrating that it cannot be simply reduced to other more frequently invoked moral concepts such as beneficence or justice. We argue that reciprocity can function as a mid-level principle in public health, and generally, captures a core social obligation arising once an individual or group is burdened as a result of acting for the benefit of others (even if they derive a benefit themselves). We conclude that while more needs to be explored in relation to the theoretical justification and application of reciprocity, sufficient arguments can be made for it to be taken more seriously as a key principle within public health ethics and bioethics more generally. PMID:26797512

  17. Reciprocity and Ethical Tuberculosis Treatment and Control.

    PubMed

    Silva, Diego S; Dawson, Angus; Upshur, Ross E G

    2016-03-01

    This paper explores the notion of reciprocity in the context of active pulmonary and laryngeal tuberculosis (TB) treatment and related control policies and practices. We seek to do three things: First, we sketch the background to contemporary global TB care and suggest that poverty is a key feature when considering the treatment of TB patients. We use two examples from TB care to explore the role of reciprocity: isolation and the use of novel TB drugs. Second, we explore alternative means of justifying the use of reciprocity through appeal to different moral and political theoretical traditions (i.e., virtue ethics, deontology, and consequentialism). We suggest that each theory can be used to provide reasons to take reciprocity seriously as an independent moral concept, despite any other differences. Third, we explore general meanings and uses of the concept of reciprocity, with the primary intention of demonstrating that it cannot be simply reduced to other more frequently invoked moral concepts such as beneficence or justice. We argue that reciprocity can function as a mid-level principle in public health, and generally, captures a core social obligation arising once an individual or group is burdened as a result of acting for the benefit of others (even if they derive a benefit themselves). We conclude that while more needs to be explored in relation to the theoretical justification and application of reciprocity, sufficient arguments can be made for it to be taken more seriously as a key principle within public health ethics and bioethics more generally.

  18. Gait synchronization in Caenorhabditis elegans

    PubMed Central

    Yuan, Jinzhou; Raizen, David M.; Bau, Haim H.

    2014-01-01

    Collective motion is observed in swarms of swimmers of various sizes, ranging from self-propelled nanoparticles to fish. The mechanisms that govern interactions among individuals are debated, and vary from one species to another. Although the interactions among relatively large animals, such as fish, are controlled by their nervous systems, the interactions among microorganisms, which lack nervous systems, are controlled through physical and chemical pathways. Little is known, however, regarding the mechanism of collective movements in microscopic organisms with nervous systems. To attempt to remedy this, we studied collective swimming behavior in the nematode Caenorhabditis elegans, a microorganism with a compact nervous system. We evaluated the contributions of hydrodynamic forces, contact forces, and mechanosensory input to the interactions among individuals. We devised an experiment to examine pair interactions as a function of the distance between the animals and observed that gait synchronization occurred only when the animals were in close proximity, independent of genes required for mechanosensation. Our measurements and simulations indicate that steric hindrance is the dominant factor responsible for motion synchronization in C. elegans, and that hydrodynamic interactions and genotype do not play a significant role. We infer that a similar mechanism may apply to other microscopic swimming organisms and self-propelled particles. PMID:24778261

  19. Neuroimaging of Freezing of Gait

    PubMed Central

    Fasano, Alfonso; Herman, Talia; Tessitore, Alessandro; Strafella, Antonio P.; Bohnen, Nicolaas I.

    2015-01-01

    Abstract Functional brain imaging techniques appear ideally suited to explore the pathophysiology of freezing of gait (FOG). In the last two decades, techniques based on magnetic resonance or nuclear medicine imaging have found a number of structural changes and functional disconnections between subcortical and cortical regions of the locomotor network in patients with FOG. FOG seems to be related in part to disruptions in the “executive-attention” network along with regional tissue loss including the premotor area, inferior frontal gyrus, precentral gyrus, the parietal and occipital areas involved in visuospatial functions of the right hemisphere. Several subcortical structures have been also involved in the etiology of FOG, principally the caudate nucleus and the locomotor centers in the brainstem. Maladaptive neural compensation may present transiently in the presence of acute conflicting motor, cognitive or emotional stimulus processing, thus causing acute network overload and resulting in episodic impairment of stepping. In this review we will summarize the state of the art of neuroimaging research for FOG. We will also discuss the limitations of current approaches and delineate the next steps of neuroimaging research to unravel the pathophysiology of this mysterious motor phenomenon. PMID:25757831

  20. Two distinct neural mechanisms underlying indirect reciprocity.

    PubMed

    Watanabe, Takamitsu; Takezawa, Masanori; Nakawake, Yo; Kunimatsu, Akira; Yamasue, Hidenori; Nakamura, Mitsuhiro; Miyashita, Yasushi; Masuda, Naoki

    2014-03-18

    Cooperation is a hallmark of human society. Humans often cooperate with strangers even if they will not meet each other again. This so-called indirect reciprocity enables large-scale cooperation among nonkin and can occur based on a reputation mechanism or as a succession of pay-it-forward behavior. Here, we provide the functional and anatomical neural evidence for two distinct mechanisms governing the two types of indirect reciprocity. Cooperation occurring as reputation-based reciprocity specifically recruited the precuneus, a region associated with self-centered cognition. During such cooperative behavior, the precuneus was functionally connected with the caudate, a region linking rewards to behavior. Furthermore, the precuneus of a cooperative subject had a strong resting-state functional connectivity (rsFC) with the caudate and a large gray matter volume. In contrast, pay-it-forward reciprocity recruited the anterior insula (AI), a brain region associated with affective empathy. The AI was functionally connected with the caudate during cooperation occurring as pay-it-forward reciprocity, and its gray matter volume and rsFC with the caudate predicted the tendency of such cooperation. The revealed difference is consistent with the existing results of evolutionary game theory: although reputation-based indirect reciprocity robustly evolves as a self-interested behavior in theory, pay-it-forward indirect reciprocity does not on its own. The present study provides neural mechanisms underlying indirect reciprocity and suggests that pay-it-forward reciprocity may not occur as myopic profit maximization but elicit emotional rewards.

  1. Two distinct neural mechanisms underlying indirect reciprocity

    PubMed Central

    Watanabe, Takamitsu; Takezawa, Masanori; Nakawake, Yo; Kunimatsu, Akira; Yamasue, Hidenori; Nakamura, Mitsuhiro; Miyashita, Yasushi; Masuda, Naoki

    2014-01-01

    Cooperation is a hallmark of human society. Humans often cooperate with strangers even if they will not meet each other again. This so-called indirect reciprocity enables large-scale cooperation among nonkin and can occur based on a reputation mechanism or as a succession of pay-it-forward behavior. Here, we provide the functional and anatomical neural evidence for two distinct mechanisms governing the two types of indirect reciprocity. Cooperation occurring as reputation-based reciprocity specifically recruited the precuneus, a region associated with self-centered cognition. During such cooperative behavior, the precuneus was functionally connected with the caudate, a region linking rewards to behavior. Furthermore, the precuneus of a cooperative subject had a strong resting-state functional connectivity (rsFC) with the caudate and a large gray matter volume. In contrast, pay-it-forward reciprocity recruited the anterior insula (AI), a brain region associated with affective empathy. The AI was functionally connected with the caudate during cooperation occurring as pay-it-forward reciprocity, and its gray matter volume and rsFC with the caudate predicted the tendency of such cooperation. The revealed difference is consistent with the existing results of evolutionary game theory: although reputation-based indirect reciprocity robustly evolves as a self-interested behavior in theory, pay-it-forward indirect reciprocity does not on its own. The present study provides neural mechanisms underlying indirect reciprocity and suggests that pay-it-forward reciprocity may not occur as myopic profit maximization but elicit emotional rewards. PMID:24591599

  2. Self-reciprocating radioisotope-powered cantilever

    NASA Astrophysics Data System (ADS)

    Li, Hui; Lal, Amit; Blanchard, James; Henderson, Douglass

    2002-07-01

    A reciprocating cantilever utilizing emitted charges from a millicurie radioisotope thin film is presented. The actuator realizes a direct collected-charge-to-motion conversion. The reciprocation is obtained by self-timed contact between the cantilever and the radioisotope source. A static model balancing the electrostatic and mechanical forces from an equivalent circuit leads to an analytical solution useful for device characterization. Measured reciprocating periods agree with predicted values from the analytical model. A scaling analysis shows that microscale arrays of such cantilevers provide an integrated sensor and actuator platform.

  3. Scrunching: a novel escape gait in planarians

    NASA Astrophysics Data System (ADS)

    Cochet-Escartin, Olivier; Mickolajczyk, Keith J.; Collins, Eva-Maria S.

    2015-10-01

    The ability to escape a predator or other life-threatening situations is central to animal survival. Different species have evolved unique strategies under anatomical and environmental constraints. In this study, we describe a novel musculature-driven escape gait in planarians, ‘scrunching’, which is quantitatively different from other planarian gaits, such as gliding and peristalsis. We show that scrunching is a conserved gait among different flatworm species, underlying its importance as an escape mechanism. We further demonstrate that it can be induced by a variety of physical stimuli, including amputation, high temperature, electric shock and low pH. We discuss the functional basis for scrunching as the preferential gait when gliding is impaired due to a disruption of mucus production. Finally, we show that the key mechanical features of scrunching are adequately captured by a simple biomechanical model that is solely based on experimental data from traction force microscopy and tissue rheology without fit parameters. Together, our results form a complete description of this novel form of planarian locomotion. Because scrunching has distinct dynamics, this gait can serve as a robust behavioral readout for studies of motor neuron and muscular functions in planarians and in particular the restoration of these functions during regeneration.

  4. Scrunching: a novel escape gait in planarians.

    PubMed

    Cochet-Escartin, Olivier; Mickolajczyk, Keith J; Collins, Eva-Maria S

    2015-09-10

    The ability to escape a predator or other life-threatening situations is central to animal survival. Different species have evolved unique strategies under anatomical and environmental constraints. In this study, we describe a novel musculature-driven escape gait in planarians, 'scrunching', which is quantitatively different from other planarian gaits, such as gliding and peristalsis. We show that scrunching is a conserved gait among different flatworm species, underlying its importance as an escape mechanism. We further demonstrate that it can be induced by a variety of physical stimuli, including amputation, high temperature, electric shock and low pH. We discuss the functional basis for scrunching as the preferential gait when gliding is impaired due to a disruption of mucus production. Finally, we show that the key mechanical features of scrunching are adequately captured by a simple biomechanical model that is solely based on experimental data from traction force microscopy and tissue rheology without fit parameters. Together, our results form a complete description of this novel form of planarian locomotion. Because scrunching has distinct dynamics, this gait can serve as a robust behavioral readout for studies of motor neuron and muscular functions in planarians and in particular the restoration of these functions during regeneration.

  5. Scrunching: a novel escape gait in planarians.

    PubMed

    Cochet-Escartin, Olivier; Mickolajczyk, Keith J; Collins, Eva-Maria S

    2015-10-01

    The ability to escape a predator or other life-threatening situations is central to animal survival. Different species have evolved unique strategies under anatomical and environmental constraints. In this study, we describe a novel musculature-driven escape gait in planarians, 'scrunching', which is quantitatively different from other planarian gaits, such as gliding and peristalsis. We show that scrunching is a conserved gait among different flatworm species, underlying its importance as an escape mechanism. We further demonstrate that it can be induced by a variety of physical stimuli, including amputation, high temperature, electric shock and low pH. We discuss the functional basis for scrunching as the preferential gait when gliding is impaired due to a disruption of mucus production. Finally, we show that the key mechanical features of scrunching are adequately captured by a simple biomechanical model that is solely based on experimental data from traction force microscopy and tissue rheology without fit parameters. Together, our results form a complete description of this novel form of planarian locomotion. Because scrunching has distinct dynamics, this gait can serve as a robust behavioral readout for studies of motor neuron and muscular functions in planarians and in particular the restoration of these functions during regeneration. PMID:26356147

  6. Sporadic hyperekplexia presenting with an ataxic gait.

    PubMed

    Rouco, Idoia; Bilbao, Iker; Losada, Jose; Maestro, Iratxe; Zarranz, Juan Jose

    2014-02-01

    We describe a 62-year-old man with a sporadic form of hyperekplexia who presented with an unsteady gait, present since the age of 47. His clinical examination revealed an insecure broad-based gait and difficulty with tandem walking but no other abnormalities. For nearly a decade the patient was misdiagnosed with an idiopathic ataxia. A video electroencephalogram combined with an electromyogram during sudden auditory stimulus demonstrated an excessive startle response. An extensive work-up ruled out all the known causes of symptomatic hyperekplexia including anti-glycine receptor antibodies. Treatment with clonazepam markedly reduced the threshold and intensity of the startle response, enabling him to recover independence. Hyperekplexia is frequently associated with an awkward and hesitating gait, but these gait abnormalities might be confused with other causes of gait disorders if one is not aware of this disease. We report this patient to highlight that a correct diagnosis of hyperekplexia is crucial, because its treatment may change quality of life. PMID:24054400

  7. Quantitative evaluation of gait ataxia by accelerometers.

    PubMed

    Shirai, Shinichi; Yabe, Ichiro; Matsushima, Masaaki; Ito, Yoichi M; Yoneyama, Mitsuru; Sasaki, Hidenao

    2015-11-15

    An appropriate biomarker for spinocerebellar degeneration (SCD) has not been identified. Here, we performed gait analysis on patients with pure cerebellar type SCD and assessed whether the obtained data could be used as a neurophysiological biomarker for cerebellar ataxia. We analyzed 25 SCD patients, 25 patients with Parkinson's disease as a disease control, and 25 healthy control individuals. Acceleration signals during 6 min of walking and 1 min of standing were measured by two sets of triaxial accelerometers that were secured with a fixation vest to the middle of the lower and upper back of each subject. We extracted two gait parameters, the average and the coefficient of variation of motion trajectory amplitude, from each acceleration component. Then, each component was analyzed by correlation with the Scale for the Assessment and Rating of Ataxia (SARA) and the Berg Balance Scale (BBS). Compared with the gait control of healthy subjects and concerning correlation with severity and disease specificity, our results suggest that the average amplitude of medial-lateral (upper back) of straight gait is a physiological biomarker for cerebellar ataxia. Our results suggest that gait analysis is a quantitative and concise evaluation scale for the severity of cerebellar ataxia.

  8. Predisability and gait patterns in older adults.

    PubMed

    Verghese, Joe; Xue, Xiaonan

    2011-01-01

    Presence of performance inconsistency during repeated assessments of gait may reflect underlying subclinical disease, and help shed light on the earliest stages of disablement. We studied inter-session fluctuations on three selected gait measures (velocity, stride length, and stride length variability) during normal pace walking as well as during a cognitively demanding 'walking while talking' condition using a repeated measurement burst design (six sessions within a 2-week period) in 71 nondisabled and nondemented community residing older adults, 40 with predisability (does activities of daily living unassisted but with difficulty). Subjects with predisability had slower gait velocity and shorter stride length on both the normal and walking while talking conditions at baseline compared to nondisabled subjects. However, there was no significant pattern of fluctuations across the six sessions on the three selected gait variables comparing the two groups during normal walking as well as on the walking while talking conditions. Our findings support consistency of gait measurements during the earliest stages of disability.

  9. Computational intelligent gait-phase detection system to identify pathological gait.

    PubMed

    Senanayake, Chathuri M; Senanayake, S M N Arosha

    2010-09-01

    An intelligent gait-phase detection algorithm based on kinematic and kinetic parameters is presented in this paper. The gait parameters do not vary distinctly for each gait phase; therefore, it is complex to differentiate gait phases with respect to a threshold value. To overcome this intricacy, the concept of fuzzy logic was applied to detect gait phases with respect to fuzzy membership values. A real-time data-acquisition system was developed consisting of four force-sensitive resistors and two inertial sensors to obtain foot-pressure patterns and knee flexion/extension angle, respectively. The detected gait phases could be further analyzed to identify abnormality occurrences, and hence, is applicable to determine accurate timing for feedback. The large amount of data required for quality gait analysis necessitates the utilization of information technology to store, manage, and extract required information. Therefore, a software application was developed for real-time acquisition of sensor data, data processing, database management, and a user-friendly graphical-user interface as a tool to simplify the task of clinicians. The experiments carried out to validate the proposed system are presented along with the results analysis for normal and pathological walking patterns.

  10. Reciprocating piston internal combustion engine

    SciTech Connect

    Hayashi, Y.

    1986-04-15

    A reciprocating piston internal combustion engine is described which consists of: a piston movably disposed within an engine cylinder, the piston having a top surface and a piston ring, the engine cylinder and the top surface of the piston defining a combustion chamber, the piston having first and second sections which are divided by a vertical plane containing an axis of a piston pin, the first section being formed with a major thrust surface and the second section being formed with a minor thrust surface; and means for thrusting the piston against a major thrust side wall of the cylinder before the piston reaches top dead center in the cylinder, the thrusting means comprising: means defining a space in the piston, the space communicating with the combustion chamber and being located in the piston second section; a movable member disposed within the space, the movable member being capable of being thrust in the direction of a minor thrust side wall of the cylinder by gas pressure within the combustion chamber and being arranged to thrust the piston ring against the minor thrust side wall when thrust by the gas pressure; and means for producing gas pressure within the combustion chamber such that the gas pressure enters the space at the compression stroke of the engine so that the movable member receives the gas pressure and is thrust toward the minor thrust side wall of the cylinder such that the piston is thrust against a major thrust side wall of the cylinder.

  11. Reciprocal engine with floating liner

    SciTech Connect

    Paul, M.A.; Paul, A.

    1989-06-27

    An internal combustion engine with a heat recovery system is described comprising: a cylinder with a cylinder wall; a piston with a piston head, the piston being reciprocally displaceable in the cylinder; a fuel injection means with fuel connected to the cylinder; and, an air intake passage and an exhaust passage connected to the cylinder, such that air is delivered to the cylinder, compressed by the piston, and fuel from the fuel injection means is delivered to the cylinder and combusted in a working chamber; wherein the heat recovery system includes an air-porous, heat-resistant tubular liner suspended in the cylinder and displaced from the wall of the cylinder, the piston having a deep groove with inner and outer walls in the head of the piston into which the liner is received when the piston is displaced compressing the air, the liner being spaced from the inner and outer walls of the groove such that three insulating zones are provided between combustion gases in the cylinder and the cylinder wall during displacement of the piston.

  12. Gait pathology assessed with Gillette Gait Index in patients after CNS tumour treatment.

    PubMed

    Syczewska, Małgorzata; Dembowska-Bagińska, Bozena; Perek-Polnik, Marta; Kalinowska, Małgorzata; Perek, Danuta

    2010-07-01

    Brain tumour is the third leading cause of death in children and adolescents younger than 16 years of age. The increasing survival rate of these patients makes their follow-up and quality of life assessment an important task. This study evaluated the gait pathology of the patients after the combined treatment for central nervous system (CNS) tumours. It assessed if the severity of gait deviation depended on the tumour site or age of illness onset. Gait analysis was performed on patients who completed the treatment (neurosurgery, chemo- and radiotherapy) and were disease-free at the time of the study. One hundred and five patients, 42 girls and 63 boys, aged 5-24 years of age, participated in the study. Depending on the location of the tumour, patients were divided into six groups. The Gillette Gait Index (GGI) was used to quantify gait deviation of patients compared to healthy subjects. Gait analysis was undertaken using VICON 460 movement analysis system. The Helen Hayes marker set was used, together with the Vicon Plug-in-Gait model. For each child the GGI was calculated separately for the left and right legs using data extracted from the subjects' averaged data. The results from left and right legs were then pooled together. To determine the effect of the tumour site and the onset of illness the ANOVA Kruskal-Wallis and correlation tests were used. The GGI did not depend on the tumour site, but demonstrated significant gait pathology in all patients. The age of illness onset appeared to influence the severity of gait deviation.

  13. Human Odometry Verifies the Symmetry Perspective on Bipedal Gaits

    ERIC Educational Resources Information Center

    Turvey, M. T.; Harrison, Steven J.; Frank, Till D.; Carello, Claudia

    2012-01-01

    Bipedal gaits have been classified on the basis of the group symmetry of the minimal network of identical differential equations (alias "cells") required to model them. Primary gaits are characterized by dihedral symmetry, whereas secondary gaits are characterized by a lower, cyclic symmetry. This fact was used in a test of human odometry. Results…

  14. Residual gait abnormalities in surgically treated spondylolisthesis.

    PubMed

    Shelokov, A; Haideri, N; Roach, J

    1993-11-01

    The authors retrospectively studied seven patients who had in situ fusion as adolescents for high-grade (IV, V) spondylolisthesis unresponsive to more conservative means. All patients achieved solid bony union; their pain was relieved; and hamstring spasm had resolved. The authors sought to determine whether crouch gait or any other abnormalities could be demonstrated in patients exhibiting clinical parameters of success. Each patient underwent gait analysis, radiographic analysis, and a physical examination. Four of seven patients demonstrated slight degrees of forward trunk lean during varying phases of gait accompanied by increased hip flexion. One patient demonstrated increased trunk extension accompanied by limited hip flexion. Two patients were essentially normal. The authors were unable to quantify residual crouch in these patients with solidly fused high-grade spondylolisthesis.

  15. An inquiry into relationship suicides and reciprocity.

    PubMed

    Davis, Mark S; Callanan, Valerie J; Lester, David; Haines, Janet

    2009-10-01

    Few theories on suicide have been grounded in the norm of reciprocity. There is literature on suicide, however, describing motivations such as retaliation and retreat which can be interpreted as modes of adaptation to the norm of reciprocity. We propose a reciprocity-based theory to explain suicides associated with relationship problems. Employing a content analysis of suicide notes, we tested the theory, finding evidence of exploitation, exploiter guilt, retaliation, and retreat as motives for committing relationship-based suicide. Reciprocity-based note writers were more likely to have used alcohol or drugs in the hours prior to committing suicide, and they were also more likely to have made their intentions known beforehand. Implications for future research as well as for suicide prevention are discussed.

  16. 78 FR 53792 - Draft Guidance for Reciprocity

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-30

    ... (Reciprocity).'' The document has been updated from the previous revision to include safety culture, security.... Brian J. McDermott, Director, Division of Materials Safety and State Agreements, Office of Federal...

  17. Footwear Decreases Gait Asymmetry during Running

    PubMed Central

    Hoerzer, Stefan; Federolf, Peter A.; Maurer, Christian; Baltich, Jennifer; Nigg, Benno M.

    2015-01-01

    Previous research on elderly people has suggested that footwear may improve neuromuscular control of motion. If footwear does in fact improve neuromuscular control, then such an influence might already be present in young, healthy adults. A feature that is often used to assess neuromuscular control of motion is the level of gait asymmetry. The objectives of the study were (a) to develop a comprehensive asymmetry index (CAI) that is capable of detecting gait asymmetry changes caused by external boundary conditions such as footwear, and (b) to use the CAI to investigate whether footwear influences gait asymmetry during running in a healthy, young cohort. Kinematic and kinetic data were collected for both legs of 15 subjects performing five barefoot and five shod over-ground running trials. Thirty continuous gait variables including ground reaction forces and variables of the hip, knee, and ankle joints were computed for each leg. For each individual, the differences between the variables for the right and left leg were calculated. Using this data, a principal component analysis was conducted to obtain the CAI. This study had two main outcomes. First, a sensitivity analysis suggested that the CAI had an improved sensitivity for detecting changes in gait asymmetry caused by external boundary conditions. The CAI may, therefore, have important clinical applications such as monitoring the progress of neuromuscular diseases (e.g. stroke or cerebral palsy). Second, the mean CAI for shod running (131.2 ± 48.5; mean ± standard deviation) was significantly lower (p = 0.041) than the CAI for barefoot running (155.7 ± 39.5). This finding suggests that in healthy, young adults gait asymmetry is reduced when running in shoes compared to running barefoot, which may be a result of improved neuromuscular control caused by changes in the afferent sensory feedback. PMID:26488484

  18. 30 CFR 57.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Reciprocating-type air compressors. 57.13010... Air and Boilers § 57.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...

  19. 30 CFR 57.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Reciprocating-type air compressors. 57.13010... Air and Boilers § 57.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...

  20. 30 CFR 57.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Reciprocating-type air compressors. 57.13010... Air and Boilers § 57.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...

  1. 30 CFR 56.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Reciprocating-type air compressors. 56.13010... and Boilers § 56.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...

  2. 30 CFR 57.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Reciprocating-type air compressors. 57.13010... Air and Boilers § 57.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...

  3. 30 CFR 56.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Reciprocating-type air compressors. 56.13010... and Boilers § 56.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...

  4. The Communications Satellite - Vehicle for a New Kind of Reciprocal Interdependence in International Adult Education

    ERIC Educational Resources Information Center

    Wedemeyer, Charles A.

    1971-01-01

    Adult education by means of communication satellites is stressed as a key to reciprocal interdependence. The author states that technological advances such as communications satellites can be used effectively to diffuse knowledge and offer options for choice in evolving societies. (RR)

  5. The Effect of Various Dual Task Training Methods with Gait on the Balance and Gait of Patients with Chronic Stroke

    PubMed Central

    An, Ho-Jung; Kim, Jae-Ic; Kim, Yang-Rae; Lee, Kyoung-Bo; Kim, Dai-Joong; Yoo, Kyung-Tae; Choi, Jung-Hyun

    2014-01-01

    [Purpose] This study examined the effects of various dual task gait training methods (motor dual task gait training, cognitive dual task gait training, and motor and cognitive dual task gait training) on the balance and gait abilities of chronic stroke patients. [Subjects and Methods] Thirty-three outpatients performed dual task gait training for 30 minutes per day, three times a week, for eight weeks from June to August, 2012. Balance ability was measured pre-and posttest using the stability test index, the weight distribution index, the functional reach test, the timed up and go test, and the four square step test. Gait ability was measured by the 10 m walk test and a 6 min walk test before and after the training. The paired t-test was used to compare measurements before and after training within each group, and ANOVA was used to compare measurements before and after training among the groups. [Results] Comparisons within each group indicated significant differences in all variables between before and after the training in all three groups. Comparison between the groups showed that the greatest improvements were seen in all tests, except for the timed up and go test, following motor and cognitive dual task gait training. [Conclusion] In a real walking environment, the motor and cognitive dual task gait training was more effective at improving the balance and gait abilities of chronic stroke patients than either the motor dual task gait training or the cognitive dual task gait training alone. PMID:25202199

  6. Acoustically-observable properties of adult gait.

    PubMed

    Bradley, Marshall; Sabatier, James M

    2012-03-01

    An approach has been developed for extracting human gait parameters from micro Doppler sonar grams. Key parameters include average speed of walking, torso velocity, walk cycle time, and peak leg velocity. The approach is a modification of a technique previously used in radar data analysis. It has been adapted because of differences between sonar and radar micro Doppler grams. The approach has been applied to an acoustic data set of 16 female and 60 male walkers. Statistics have been tabulated that illustrate the similarities and dissimilarities between female and male gait. Males tend to walk with larger walk cycle times and peak leg velocities than females.

  7. Periodic gaits for the CMU ambler

    NASA Technical Reports Server (NTRS)

    Mahalingam, Swaminathan; Dwivedi, Suren N.

    1989-01-01

    The configuration of the Carnegie Mellon University Ambler, a six legged autonomous walking vehicle for exploring Mars, enables the recovery of a trailing leg past the leading leg to reduce the energy expenditure in terrain interactions. Gaits developed for this unprecedented configuration are described. A stability criterion was developed which ensures stability of the vehicle in the event of failure of any one of the supporting legs. Periodic gaits developed for the Ambler utilize the Ambler's unique abilities, and continuously satisfy the stability criterion.

  8. Acoustically-observable properties of adult gait.

    PubMed

    Bradley, Marshall; Sabatier, James M

    2012-03-01

    An approach has been developed for extracting human gait parameters from micro Doppler sonar grams. Key parameters include average speed of walking, torso velocity, walk cycle time, and peak leg velocity. The approach is a modification of a technique previously used in radar data analysis. It has been adapted because of differences between sonar and radar micro Doppler grams. The approach has been applied to an acoustic data set of 16 female and 60 male walkers. Statistics have been tabulated that illustrate the similarities and dissimilarities between female and male gait. Males tend to walk with larger walk cycle times and peak leg velocities than females. PMID:22423810

  9. A stochastic model of human gait dynamics

    NASA Astrophysics Data System (ADS)

    Ashkenazy, Yosef; M. Hausdorff, Jeffrey; Ch. Ivanov, Plamen; Eugene Stanley, H.

    2002-12-01

    We present a stochastic model of gait rhythm dynamics, based on transitions between different “neural centers”, that reproduces distinctive statistical properties of normal human walking. By tuning one model parameter, the transition (hopping) range, the model can describe alterations in gait dynamics from childhood to adulthood-including a decrease in the correlation and volatility exponents with maturation. The model also generates time series with multifractal spectra whose broadness depends only on this parameter. Moreover, we find that the volatility exponent increases monotonically as a function of the width of the multifractal spectrum, suggesting the possibility of a change in multifractality with maturation.

  10. Gait transitions during unrestrained locomotion in dogs.

    PubMed

    Blaszczyk, J W

    2001-04-01

    Gait transitions during long distance, unrestrained locomotion were studied in 22 mongrel dogs. Spatial and temporal limb movement parameters were collected and the phase relationships between limb movements based upon a 2-dimensional (2-D) gait diagram were computed. During most of the trials, the dogs trotted within a relatively narrow velocity range. Gait transitions were observed during radical changes of the movement velocity. In most cases the gait switches were abrupt and completed within 2 strides of the gait cycle. The dogs walked, depending on the animal size, within the upper velocity range of 0.93-1.21 m/s. Most of the walk-trot transitions were observed within this range. All of them had a typical pattern that involved changes of the phase shift between diagonal limb movements from 0.31 +/- 0.02 (a typical value for a walking dog) down to 0.02 +/- 0.03. These changes appeared abruptly within one stride cycle for each diagonal pair of limbs; therefore, the transition was completed in 2 strides of the gait cycle. The switch involved momentary shortening of the hindlimb amplitudes. During the next gait cycle, all limb movement amplitudes were reduced with a concomitant increase in limb movement frequencies. In contrast to the clear border between the symmetrical gaits, the dogs switched to gallop at any speed within the trot range (most frequently between 1.5-2.6 m/s). The transitions were usually completed within one stride of the diagonal limbs. In most cases, the switch from trot to gallop had a similar pattern; while maintaining synchronous movement of one diagonal pair of limbs, the other pair movement control was modified accordingly. The typical transition pattern involved the shortening of the swing phase in the front limb with simultaneous lengthening of the swing phase in the diagonal hindlimb. These transient modifications had their equivalent in the analogous limb movement amplitude changes. A mirror-image pattern of phase changes was observed

  11. Freezing of gait in Parkinson's disease: from pathophysiology to emerging therapies.

    PubMed

    Cucca, Alberto; Biagioni, Milton C; Fleisher, Jori E; Agarwal, Shashank; Son, Andre; Kumar, Pawan; Brys, Miroslaw; Di Rocco, Alessandro

    2016-10-01

    Freezing of gait (FOG) is 'an episodic inability to generate effective stepping in the absence of any known cause other than parkinsonism or high level gait disorders'. FOG is one of the most disabling symptoms in Parkinson's disease, especially in its more advanced stages. Early recognition is important as FOG is related to higher fall risk and poorer prognosis. Although specific treatments are still elusive, there have been recent advances in the development of new therapeutic approaches. The aim of this review is to present the latest knowledge regarding the phenomenology, pathogenesis, diagnostic assessment and conventional treatment of FOG in Parkinson's disease. A review of the evidence supporting noninvasive brain stimulation will follow to highlight the potential of these strategies. PMID:27599588

  12. Prediction of Freezing of Gait in Parkinson's From Physiological Wearables: An Exploratory Study.

    PubMed

    Mazilu, Sinziana; Calatroni, Alberto; Gazit, Eran; Mirelman, Anat; Hausdorff, Jeffrey M; Tröster, Gerhard

    2015-11-01

    Freezing of gait (FoG) is a common gait impairment among patients with advanced Parkinson's disease. FoG is associated with falls and negatively impacts the patient's quality of life. Wearable systems that detect FoG in real time have been developed to help patients resume walking by means of rhythmic cueing. Current methods focus on detection, which require FoG events to happen first, while their prediction opens the road to preemptive cueing, which might help subjects to avoid freeze altogether. We analyzed electrocardiography (ECG) and skin-conductance (SC) data from 11 subjects who experience FoG in daily life, and found statistically significant changes in ECG and SC data just before the FoG episodes, compared to normal walking. Based on these findings, we developed an anomaly-based algorithm for predicting gait freeze from relevant SC features. We were able to predict 71.3% from 184 FoG with an average of 4.2 s before a freeze episode happened. Our findings enable the possibility of wearable systems, which predict with few seconds before an upcoming FoG from SC, and start external cues to help the user avoid the gait freeze.

  13. Gait analysis in lower-limb amputation and prosthetic rehabilitation.

    PubMed

    Esquenazi, Alberto

    2014-02-01

    Gait analysis combined with sound clinical judgment plays an important role in elucidating the factors involved in the pathologic prosthetic gait and the selection and effects of available interventions to optimize it. Detailed clinical evaluation of walking contributes to the analysis of the prosthetic gait, but evaluation in the gait laboratory using kinetic and kinematic data is often necessary to quantify and identify the particular contributions of the variables impacting the gait with confidence and assess the results of such intervention. The same approach can be considered when selecting prosthetic components and assessing leg length in this patient population.

  14. Fluctuation and synchronization of gait intervals and gait force profiles distinguish stages of Parkinson's disease

    NASA Astrophysics Data System (ADS)

    Bartsch, Ronny; Plotnik, Meir; Kantelhardt, Jan W.; Havlin, Shlomo; Giladi, Nir; Hausdorff, Jeffrey M.

    2007-09-01

    We study the effects of Parkinson's disease (PD) on the long-term fluctuation and phase synchronization properties of gait timing (series of interstride intervals) as well as gait force profiles (series characterizing the morphological changes between the steps). We find that the fluctuations in the gait timing are significantly larger for PD patients and early PD patients, who were not treated yet with medication, compared to age-matched healthy controls. Simultaneously, the long-term correlations and the phase synchronization of right and left leg are significantly reduced in both types of PD patients. Surprisingly, long-term correlations of the gait force profiles are relatively weak for treated PD patients and healthy controls, while they are significantly larger for early PD patients. The results support the idea that timing and morphology of recordings obtained from a complex system can contain complementary information.

  15. Disturbances of automatic gait control mechanisms in higher level gait disorder.

    PubMed

    Danoudis, Mary; Ganesvaran, Ganga; Iansek, Robert

    2016-07-01

    The underlying mechanisms responsible for the gait changes in frontal gait disorder (FGD), a form of higher level gait disorders, are poorly understood. We investigated the relationship between stride length and cadence (SLCrel) in people with FGD (n=15) in comparison to healthy older adults (n=21) to improve our understanding of the changes to gait in FGD. Gait data was captured using an electronic walkway system as participants walked at five self-selected speed conditions: preferred, very slow, slow, fast and very fast. Linear regression was used to determine the strength of the relationship (R(2)), slope and intercept. In the FGD group 9 participants had a strong SLCrel (linear group) (R(2)>0.8) and 6 a weak relationship (R(2)<0.8) (nonlinear group). The linear FGD group did not differ to healthy control for slope (p>0.05) but did have a lower intercept (p<0.001). The linear FGD group modulated gait speed by adjusting stride length and cadence similar to controls whereas the nonlinear FGD participants adjusted stride length but not cadence similar to controls. The non-linear FGD group had greater disturbance to their gait, poorer postural control and greater fear of falling compared to the linear FGD group. Investigation of the SLCrel resulted in new insights into the underlying mechanisms responsible for the gait changes found in FGD. The findings suggest stride length regulation was disrupted in milder FGD but as the disorder worsened, cadence control also became disordered resulting in a break down in the relationship between stride length and cadence. PMID:27477707

  16. Basic gait analysis based on continuous wave radar.

    PubMed

    Zhang, Jun

    2012-09-01

    A gait analysis method based on continuous wave (CW) radar is proposed in this paper. Time-frequency analysis is used to analyze the radar micro-Doppler echo from walking humans, and the relationships between the time-frequency spectrogram and human biological gait are discussed. The methods for extracting the gait parameters from the spectrogram are studied in depth and experiments on more than twenty subjects have been performed to acquire the radar gait data. The gait parameters are calculated and compared. The gait difference between men and women are presented based on the experimental data and extracted features. Gait analysis based on CW radar will provide a new method for clinical diagnosis and therapy.

  17. Basic gait analysis based on continuous wave radar.

    PubMed

    Zhang, Jun

    2012-09-01

    A gait analysis method based on continuous wave (CW) radar is proposed in this paper. Time-frequency analysis is used to analyze the radar micro-Doppler echo from walking humans, and the relationships between the time-frequency spectrogram and human biological gait are discussed. The methods for extracting the gait parameters from the spectrogram are studied in depth and experiments on more than twenty subjects have been performed to acquire the radar gait data. The gait parameters are calculated and compared. The gait difference between men and women are presented based on the experimental data and extracted features. Gait analysis based on CW radar will provide a new method for clinical diagnosis and therapy. PMID:22951210

  18. Primary and secondary gait deviations of stroke survivors and their association with gait performance

    PubMed Central

    Kim, Hyung-Sik; Chung, Soon-Cheol; Choi, Mi-Hyun; Gim, Seon-Young; Kim, Woo-Ram; Tack, Gye-Rae; Lim, Dae-Woon; Chun, Sung-Kuk; Kim, Jin-Wook; Mun, Kyung-Ryoul

    2016-01-01

    [Purpose] Stroke survivors exhibit abnormal pelvic motion and significantly deteriorated gait performance. Although the gait of stroke survivors has been evaluated at the primary level pertaining to ankle, knee, and hip motions, secondary deviations involving the pelvic motions are strongly related to the primary level. Therefore, the aim of this study was to identify the kinematic differences of the primary and secondary joints and to identify mechanism differences that alter the gait performance of stroke survivors. [Subjects and Methods] Five healthy subjects and five stroke survivors were recruited. All the subjects were instructed to walk at a self-selected speed. The joint kinematics and gait parameters were calculated. [Results] For the stroke survivors, the range of motion of the primary-joint motions were significantly reduced, and the secondary-joint motions were significantly increased. Additionally, for the healthy subjects, the primary joint kinematics were the main factors ensuring gait performance, whereas for the stoke survivors, the secondary-joint motions were the main factors. [Conclusion] The results indicate that while increasing the range of motion of primary-joint movements is the main target to achieve, there is a strong need to constrain and support pelvic motions in order to improve the outcome of gait rehabilitation. PMID:27799710

  19. Multilayer Joint Gait-Pose Manifolds for Human Gait Motion Modeling.

    PubMed

    Ding, Meng; Fan, Guolian

    2015-11-01

    We present new multilayer joint gait-pose manifolds (multilayer JGPMs) for complex human gait motion modeling, where three latent variables are defined jointly in a low-dimensional manifold to represent a variety of body configurations. Specifically, the pose variable (along the pose manifold) denotes a specific stage in a walking cycle; the gait variable (along the gait manifold) represents different walking styles; and the linear scale variable characterizes the maximum stride in a walking cycle. We discuss two kinds of topological priors for coupling the pose and gait manifolds, i.e., cylindrical and toroidal, to examine their effectiveness and suitability for motion modeling. We resort to a topologically-constrained Gaussian process (GP) latent variable model to learn the multilayer JGPMs where two new techniques are introduced to facilitate model learning under limited training data. First is training data diversification that creates a set of simulated motion data with different strides. Second is the topology-aware local learning to speed up model learning by taking advantage of the local topological structure. The experimental results on the Carnegie Mellon University motion capture data demonstrate the advantages of our proposed multilayer models over several existing GP-based motion models in terms of the overall performance of human gait motion modeling.

  20. Regulation of Gait in Long Jumping.

    ERIC Educational Resources Information Center

    Lee, David N.; And Others

    1982-01-01

    The way in which skilled long jumpers regulate their gait during their run-up to the takeoff board was investigated. The run-up consists of (1) an initial accelerative phase, and (2) a zeroing-in phase. Their skill varied with the adjustment of the impulse of their steps toward the end of the run-up. (Author/BW)

  1. Neurological update: emerging issues in gait disorders.

    PubMed

    Lewis, Simon J G

    2015-06-01

    Gait disorders represent a common and diverse challenge in Neurological practice. The literature on this field is expanding and is seeking to address mainstream clinical issues as well as a greater understanding of pathophysiological mechanisms. This update will introduce a range of these concepts. PMID:25736555

  2. Effects of gait velocity and center of mass acceleration during turning gait in old-old elderly women

    PubMed Central

    Shin, Sun-Shil; Yoo, Won-Gyu

    2015-01-01

    [Purpose] This study investigated gait velocity and center of mass acceleration in three directions during square and semicircular turning gait tasks in old-old elderly women. [Subjects] Fifteen community-dwelling, old-old elderly women (≥75 years old) who could walk independently were recruited. [Methods] We measured gait velocity and center of mass acceleration in three directions using an accelerometer during two different turning gait tasks. [Results] The velocity during square turning was significantly slower than that during semicircular turning gait. There were no significant differences between gait tasks with respect to normalized antero-posterior, medo-lateral, or vertical center of mass acceleration. [Conclusion] Changing the direction of travel while walking regardless of turning angle is one of the greatest challenges for balance in old-old elderly people. Furthermore, gait velocity is a useful clinical marker for predicting falls in old-old elderly populations. PMID:26180319

  3. Gait recognition based on Kinect sensor

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohammed; Al-Jawad, Naseer; Sabir, Azhin T.

    2014-05-01

    This paper presents gait recognition based on human skeleton and trajectory of joint points captured by Microsoft Kinect sensor. In this paper Two sets of dynamic features are extracted during one gait cycle: the first is Horizontal Distance Features (HDF) that is based on the distances between (Ankles, knees, hands, shoulders), the second set is the Vertical Distance Features (VDF) that provide significant information of human gait extracted from the height to the ground of (hand, shoulder, and ankles) during one gait cycle. Extracting these two sets of feature are difficult and not accurate based on using traditional camera, therefore the Kinect sensor is used in this paper to determine the precise measurements. The two sets of feature are separately tested and then fused to create one feature vector. A database has been created in house to perform our experiments. This database consists of sixteen males and four females. For each individual, 10 videos have been recorded, each record includes in average two gait cycles. The Kinect sensor is used here to extract all the skeleton points, and these points are used to build up the feature vectors mentioned above. K-nearest neighbor is used as the classification method based on Cityblock distance function. Based on the experimental result the proposed method provides 56% as a recognition rate using HDF, while VDF provided 83.5% recognition accuracy. When fusing both of the HDF and VDF as one feature vector, the recognition rate increased to 92%, the experimental result shows that our method provides significant result compared to the existence methods.

  4. Comparison of Gait Aspects According to FES Stimulation Position Applied to Stroke Patients.

    PubMed

    Mun, Byeong-Mu; Kim, Tae-Ho; Lee, Jin-Hwan; Lim, Jin-Youg; Seo, Dong-Kwon; Lee, Dong-Jin

    2014-04-01

    [Purpose] This study sought to identify the gait aspects according to the FES stimulation position in stroke patients during gait training. [Subjects and Methods] To perform gait analysis, ten stroke patients were grouped based on 4 types of gait conditions: gait without FES stimulation (non-FES), gait with FES stimulation on the tibialis anterior (Ta), gait with FES stimulation on the tibialis anterior and quadriceps (TaQ), and gait with FES stimulation on the tibialis anterior and gluteus medius (TaGm). [Results] Based on repeated measures analysis of variance of measurements of gait aspects comprised of gait speed, gait cycle, and step length according to the FES stimulation position, the FES stimulation significantly affected gait aspects. [Conclusion] In conclusion, stimulating the tibialis anterior and quadriceps and stimulating the tibialis anterior and gluteus medius are much more effective than stimulating only the tibialis anterior during gait training in stroke patients using FES.

  5. Evolution of indirect reciprocity in groups of various sizes and comparison with direct reciprocity.

    PubMed

    Suzuki, Shinsuke; Akiyama, Eizo

    2007-04-01

    Recently many studies have investigated the evolution of indirect reciprocity through which cooperative action is returned by a third individual, e.g. individual A helped B and then receives help from C. Most studies on indirect reciprocity have presumed that only two individuals take part in a single interaction (group), e.g. A helps B and C helps A. In this paper, we investigate the evolution of indirect reciprocity when more than two individuals take part in a single group, and compare the result with direct reciprocity through which cooperative action is directly returned by the recipient. Our analyses show the following. In the population with discriminating cooperators and unconditional defectors, whether implementation error is included or not, (i) both strategies are evolutionarily stable and the evolution of indirect reciprocity becomes more difficult as group size increases, and (ii) the condition for the evolution of indirect reciprocity under standing reputation criterion where the third individuals distinguish between justified and unjustified defections is more relaxed than that under image scoring reputation criterion in which the third individuals do not distinguish with. Furthermore, in the population that also includes unconditional cooperators, (iii) in the presence of errors in implementation, the discriminating strategy is evolutionarily stable not only under standing but also under image scoring if group size is larger than two. Finally, (iv) in the absence of errors in implementation, the condition for the evolution of direct reciprocity is equivalent to that for the evolution of indirect reciprocity under standing, and, in the presence of errors, the condition for the evolution of direct reciprocity is very close to that for the evolution of indirect reciprocity under image scoring.

  6. Three-person game facilitates indirect reciprocity under image scoring.

    PubMed

    Suzuki, Shinsuke; Akiyama, Eizo

    2007-11-01

    Reputation building plays an important role in the evolution of reciprocal altruism when the same individuals do not interact repeatedly because, by referring to reputation, a reciprocator can know which partners are cooperative and can reciprocate with a cooperator. This reciprocity based on reputation is called indirect reciprocity. Previous studies of indirect reciprocity have focused only on two-person games in which only two individuals participate in a single interaction, and have claimed that indirectly reciprocal cooperation cannot be established under image scoring reputation criterion where the reputation of an individual who has cooperated (defected) becomes good (bad). In this study, we specifically examine three-person games, and reveal that indirectly reciprocal cooperation can be formed and maintained stably, even under image scoring, by a nucleus shield mechanism. In the nucleus shield, reciprocators are a shield that keeps out unconditional defectors, whereas unconditional cooperators are the backbone of cooperation that retains a good reputation among the population.

  7. Mutuality and reciprocity in the psychological contracts of employees and employers.

    PubMed

    Dabos, Guillermo E; Rousseau, Denise M

    2004-02-01

    The authors assessed the joint perceptions of the employee and his or her employer to examine mutuality and reciprocity in the employment relationship. Paired psychological contract reports were obtained from 80 employee-employer dyads in 16 university-based research centers. On the basis of in-depth study of the research setting, research directors were identified as primary agents for the university (employer) in shaping the terms of employment of staff scientists (employees). By assessing the extent of consistency between employee and employer beliefs regarding their exchange agreement, the present study mapped the variation and consequences of mutuality and reciprocity in psychological contracts. Results indicate that both mutuality and reciprocity are positively related to archival indicators of research productivity and career advancement, in addition to self-reported measures of Met Expectations and intention to continue working with the employer. Implications for psychological contract theory are presented.

  8. [Gait disturbances related to dysfunction of the cerebral cortex and basal ganglia].

    PubMed

    Takezawa, Nobuo; Mizuno, Toshiki; Seo, Kazuya; Kondo, Masaki; Nakagawa, Masanori

    2010-11-01

    This review aimed to characterize the gait disturbances in Parkinson disease (PD) and highlight how a rehabilitation program would affect the care of patients with PD. The typical PD gait is a type of hypokinetic gait characterized by reduced stride length and velocity; shortening of the swing phase; and increase in the stance phase, double-limb support duration, and cadence rate. In the advanced phase of PD, start hesitation, shuffling and festinating gait, propulsion, and freezing of gait (FOG) become remarkable. Notably, in PD, attention may influence gait control, and sensory cueing may improve the stride length. Our study on gait impairment in PD by using a three-dimensional motion analysis system revealed that the stride length and walking speed decreased, but there was no change in cadence. The decreased stride length was due to reduction in the range of movement at the leg and pelvic joints. A 4-week physical rehabilitation program for PD improved the stride length and walking speed;this was achieved by increasing the range of movement of at the leg and pelvic joints. We also assessed the effects of a rehabilitation program for patients with PD who experienced FOG. Although the lower limb function was more impaired in patients with PD and FOG than in those with PD without FOG, the rehabilitation program was effective even for patients with PD and FOG. FOG might be associated with functional impairment of the lower limb as well as dysfunction of the fronto-basal ganglia circuit. We also reported 3 cases of camptocormia (bent spine syndrome) with autonomic dysfunction and rapid eye movement (REM) sleep behavior disorders (RBD) and compared their symptoms with those reported elsewhere. We think that the pedunculopontine nuclear area may control the postural muscle tone and locomotion in PD. On the basis of the results of our rehabilitation programs, we speculate that physical modalities may modify synaptic plasticity by utilizing the cerebellar and/or afferent

  9. Characterization of gait in late onset Pompe disease.

    PubMed

    McIntosh, Paul T; Case, Laura E; Chan, Justin M; Austin, Stephanie L; Kishnani, Priya

    2015-11-01

    The skeletal muscle manifestations of late-onset Pompe disease (LOPD) cause significant gait impairment. However, the specific temporal and spatial characteristics of abnormal gait in LOPD have not been objectively analyzed or described in the literature. This pilot study evaluated the gait of 22 individuals with LOPD using the GAITRite® temporospatial gait analysis system. The gait parameters were compared to normal reference values, and correlations were made with standard measures of disease progression. The LOPD population demonstrated significant abnormalities in temporospatial parameters of gait including a trend towards decreased velocity and cadence, a prolonged stance phase, prolonged time in double limb support, shorter step and stride length, and a wider base of support. Precise descriptions and analyses of gait abnormalities have much potential in increasing our understanding of LOPD, especially in regards to how its natural history may be modified by the use of enzyme replacement therapy (ERT) and other interventions. Gait analysis may provide a sensitive early marker of the onset of clinical symptoms and signs, offer an additional objective measure of disease progression and the impact of intervention, and serve as a potentially important clinical endpoint. The additional data from comprehensive gait analysis may personalize and optimize physical therapy management, and the clarification of specific gait patterns in neuromuscular diseases could be of clinical benefit in the ranking of a differential diagnosis.

  10. Tract-specific white matter microstructure and gait in humans.

    PubMed

    Verlinden, Vincentius J A; de Groot, Marius; Cremers, Lotte G M; van der Geest, Jos N; Hofman, Albert; Niessen, Wiro J; van der Lugt, Aad; Vernooij, Meike W; Ikram, M Arfan

    2016-07-01

    Gait is a complex sequence of movements, requiring cooperation of many brain areas, such as the motor cortex, somatosensory cortex, and cerebellum. However, it is unclear which connecting white matter tracts are essential for communication across brain areas to facilitate proper gait. Using diffusion tensor imaging, we investigated associations of microstructural organization in 14 brain white matter tracts with gait, among 2330 dementia- and stroke-free community-dwelling individuals. Gait was assessed by electronic walkway and summarized into Global Gait, and 7 gait domains. Higher white matter microstructure associated with higher Global Gait, Phases, Variability, Pace, and Turning. Microstructure in thalamic radiations, followed by association tracts and the forceps major, associated most strongly with gait. Hence, in community-dwelling individuals, higher white matter microstructure associated with better gait, including larger strides, more single support, less stride-to-stride variability, and less turning steps. Our findings suggest that intact thalamocortical communication, cortex-to-cortex communication, and interhemispheric visuospatial integration are most essential in human gait. PMID:27255826

  11. Five-Year-Old Preschoolers’ Sharing is Influenced by Anticipated Reciprocation

    PubMed Central

    Xiong, Mingrui; Shi, Jiannong; Wu, Zhen; Zhang, Zhen

    2016-01-01

    Whether children share in anticipation of future benefits returned by a partner is an interesting question. In this study, 5-year-old children and an adult partner played a sharing game, in which children donated first and the partner donated afterward. In Experiment 1, the partner’s resources were more attractive than the child’s. In the reciprocal condition, the child was told that s/he would be a recipient when the partner played as a donor. In the non-reciprocal condition, however, the child was told that an anonymous child would be the recipient when the partner donated. Results showed that children shared more with the partner when they knew that they would be a recipient later. In Experiment 2, the child was always the recipient when the partner donated, but the partner’s resources were more desirable than the child’s in the high-value condition, and less desirable in the low-value condition. We found that children were more generous when the partner’s resources were valued higher. These findings demonstrate that 5-year-old preschoolers’ sharing choices take into account the anticipated reciprocity of the recipient, suggesting either self-interested tactical sharing or direct reciprocity in advance of receiving. Specifically, they adjust their sharing behavior depending on whether a partner has the potential to reciprocate, and whether it is worth sharing relative to the value of the payback. PMID:27064475

  12. Measuring and making decisions for social reciprocity.

    PubMed

    Solanas, Antonio; Leiva, David; Sierra, Vicenta; Salafranca, Lluís

    2009-08-01

    Social reciprocity may explain certain emerging psychological processes likely to be founded on dyadic relations. Although indexes and statistics have been proposed to measure and make statistical decisions regarding social reciprocity in groups, these tools were generally developed to identify association patterns rather than to quantify the discrepancies between what each individual addresses to his or her partners and what is received from those partners in return. Additionally, social researchers' interest extends beyond measuring groups at the global level because dyadic and individual measurements are also necessary for proper descriptions of social interactions. This study is concerned with a new statistic for measuring social reciprocity at the global level and with decomposing that statistic in order to identify which dyads and individuals account for a significant part of asymmetry in social interactions. In addition to a set of indexes, some exact analytical results are derived, and a way of making statistical decisions is proposed.

  13. Theory of reciprocating contact for viscoelastic solids

    NASA Astrophysics Data System (ADS)

    Putignano, Carmine; Carbone, Giuseppe; Dini, Daniele

    2016-04-01

    A theory of reciprocating contacts for linear viscoelastic materials is presented. Results are discussed for the case of a rigid sphere sinusoidally driven in sliding contact with a viscoelastic half-space. Depending on the size of the contact, the frequency and amplitude of the reciprocating motion, and on the relaxation time of the viscoelastic body, we establish that the contact behavior may range from the steady-state viscoelastic solution, in which traction forces always oppose the direction of the sliding rigid punch, to a more elaborate trend, which is due to the strong interaction between different regions of the path covered during the reciprocating motion. Practical implications span a number of applications, ranging from seismic engineering to biotechnology.

  14. Gauge invariance and reciprocity in quantum mechanics

    SciTech Connect

    Leung, P. T.; Young, K.

    2010-03-15

    Reciprocity in wave propagation usually refers to the symmetry of the Green's function under the interchange of the source and the observer coordinates, but this condition is not gauge invariant in quantum mechanics, a problem that is particularly significant in the presence of a vector potential. Several possible alternative criteria are given and analyzed with reference to different examples with nonzero magnetic fields and/or vector potentials, including the case of a multiply connected spatial domain. It is shown that the appropriate reciprocity criterion allows for specific phase factors separable into functions of the source and observer coordinates and that this condition is robust with respect to the addition of any scalar potential. In the Aharonov-Bohm effect, reciprocity beyond monoenergetic experiments holds only because of subsidiary conditions satisfied in actual experiments: the test charge is in units of e and the flux is produced by a condensate of particles with charge 2e.

  15. Gait in 5-year-old children with idiopathic clubfoot

    PubMed Central

    Lööf, Elin; Andriesse, Hanneke; André, Marie; Böhm, Stephanie; Broström, Eva W

    2016-01-01

    Background and purpose Idiopathic clubfoot can be bilateral or unilateral; however, most studies of gait have assessed clubfoot cases as one uniform group. The contralateral foot in children with unilateral clubfoot has shown deviations in pedobarographic measurements, but it is seldom included in studies of gait. We evaluated gait in children with idiopathic clubfoot, concentrating on foot involvement. Patients and methods Three-dimensional gait analyses of 59 children, mean age 5.4 years, with bilateral (n = 30) or unilateral (n = 29) idiopathic clubfoot were stratified into groups of bilateral, unilateral, or contralateral feet. Age-matched controls (n = 28) were evaluated for comparison. Gait assessment included: (1) discrete kinematic and kinetic parameters, and (2) gait deviation index for kinematics (GDI) and kinetics (GDI-k). Results No differences in gait were found between bilateral and unilateral idiopathic clubfoot, but both groups deviated when compared to controls. Compared to control feet, contralateral feet showed no deviations in discrete gait parameters, but discrepancies were evident in relation to unilateral clubfoot, causing gait asymmetries in children with unilateral involvement. However, all groups deviated significantly from control feet according to GDI and GDI-k. Interpretation Bilateral and unilateral idiopathic clubfoot cases show the same persistent deviations in gait, mainly regarding reduced plantarflexion. Nevertheless, knowledge of foot involvement is important as children with unilateral clubfoot show gait asymmetries, which might give an impression of poorer deviations. The results of GDI/GDI-k indicate global gait adaptations of the contralateral foot, so the foot should preferably not be used as a reference for gait. PMID:27331243

  16. Kinematic analysis quantifies gait abnormalities associated with lameness in broiler chickens and identifies evolutionary gait differences.

    PubMed

    Caplen, Gina; Hothersall, Becky; Murrell, Joanna C; Nicol, Christine J; Waterman-Pearson, Avril E; Weeks, Claire A; Colborne, G Robert

    2012-01-01

    This is the first time that gait characteristics of broiler (meat) chickens have been compared with their progenitor, jungle fowl, and the first kinematic study to report a link between broiler gait parameters and defined lameness scores. A commercial motion-capturing system recorded three-dimensional temporospatial information during walking. The hypothesis was that the gait characteristics of non-lame broilers (n = 10) would be intermediate to those of lame broilers (n = 12) and jungle fowl (n = 10, tested at two ages: immature and adult). Data analysed using multi-level models, to define an extensive range of baseline gait parameters, revealed inter-group similarities and differences. Natural selection is likely to have made jungle fowl walking gait highly efficient. Modern broiler chickens possess an unbalanced body conformation due to intense genetic selection for additional breast muscle (pectoral hypertrophy) and whole body mass. Together with rapid growth, this promotes compensatory gait adaptations to minimise energy expenditure and triggers high lameness prevalence within commercial flocks; lameness creating further disruption to the gait cycle and being an important welfare issue. Clear differences were observed between the two lines (short stance phase, little double-support, low leg lift, and little back displacement in adult jungle fowl; much double-support, high leg lift, and substantial vertical back movement in sound broilers) presumably related to mass and body conformation. Similarities included stride length and duration. Additional modifications were also identified in lame broilers (short stride length and duration, substantial lateral back movement, reduced velocity) presumably linked to musculo-skeletal abnormalities. Reduced walking velocity suggests an attempt to minimise skeletal stress and/or discomfort, while a shorter stride length and time, together with longer stance and double-support phases, are associated with

  17. Feasibility analysis of reciprocating magnetic heat pumps

    NASA Technical Reports Server (NTRS)

    Larson, A. V.; Hartley, J. G.; Shelton, Sam V.; Smith, M. M.

    1989-01-01

    A reciprocating gadolinium core in a regeneration fluid column in the warm bore of a superconducting solenoidal magnet is considered for magnetic refrigeration in 3.517 MW (1000 ton) applications. A procedure is presented to minimize the amount of superconducting cable needed in the magnet design. Estimated system capital costs for an ideal magnetic refrigerator of this type become comparable to conventional chillers as the frequency of reciprocation approaches 10 Hertz. A 1-D finite difference analysis of a regenerator cycling at 0.027 Hertz is presented which exhibits some of the features seen in the experiments of G. V. Brown.

  18. Analysis of reciprocating compressor piston rod failures

    SciTech Connect

    Tripp, H.A.; Drosjack, M.J.

    1984-02-01

    This report presents the analysis of five piston rod failures which occurred on reciprocating compressors. Calculations are shown for rod stress which includes nominal rod loading sources as well as additional loads due to unusual pressure losses in the compressor valves, flexure of the rods due to misalignment, and manufacturing errors. The additional loads were incorporated on the basis of field measurements. The stress values are used with Baquin's equation to produce fatigue life curves for the rods. Based on the calculations, recommendations for modified rods were made. The calculation procedures are described in a manner which will permit their application to other reciprocating compressors.

  19. Biomechanical demands of the 2-step transitional gait cycles linking level gait and stair descent gait in older women.

    PubMed

    Alcock, Lisa; O'Brien, Thomas D; Vanicek, Natalie

    2015-12-16

    Stair descent is an inherently complex form of locomotion posing a high falls risk for older adults, specifically when negotiating the transitional gait cycles linking level gait and descent. The aim of this study was to enhance our understanding of the biomechanical demands by comparing the demands of these transitions. Lower limb kinematics and kinetics of the 2-step transitions linking level and descent gait at the top (level-to-descent) and the bottom (descent-to-level) of the staircase were quantified in 36 older women with no falls history. Despite undergoing the same vertical displacement (2-steps), the following significant (p<.05) differences were observed during the top transition compared to the bottom transition: reduced step velocity; reduced hip extension and increased ankle dorsiflexion (late stance/pre-swing); reduced ground reaction forces, larger knee extensor moments and powers (absorption; late stance); reduced ankle plantarflexor moments (early and late stance) and increased ankle powers (mid-stance). Top transition biomechanics were similar to those reported previously for continuous descent. Kinetic differences at the knee and ankle signify the contrasting and prominent functions of controlled lowering during the top transition and forward continuance during the bottom transition. The varying musculoskeletal demands encountered during each functional sub-task should be addressed in falls prevention programmes with elderly populations where the greatest clinical impact may be achieved. Knee extensor eccentric power through flexion exercises would facilitate a smooth transition at the top and improving ankle plantarflexion strength during single and double limb stance activities would ease the transition into level gait following continuous descent. PMID:26592439

  20. Biomechanical demands of the 2-step transitional gait cycles linking level gait and stair descent gait in older women.

    PubMed

    Alcock, Lisa; O'Brien, Thomas D; Vanicek, Natalie

    2015-12-16

    Stair descent is an inherently complex form of locomotion posing a high falls risk for older adults, specifically when negotiating the transitional gait cycles linking level gait and descent. The aim of this study was to enhance our understanding of the biomechanical demands by comparing the demands of these transitions. Lower limb kinematics and kinetics of the 2-step transitions linking level and descent gait at the top (level-to-descent) and the bottom (descent-to-level) of the staircase were quantified in 36 older women with no falls history. Despite undergoing the same vertical displacement (2-steps), the following significant (p<.05) differences were observed during the top transition compared to the bottom transition: reduced step velocity; reduced hip extension and increased ankle dorsiflexion (late stance/pre-swing); reduced ground reaction forces, larger knee extensor moments and powers (absorption; late stance); reduced ankle plantarflexor moments (early and late stance) and increased ankle powers (mid-stance). Top transition biomechanics were similar to those reported previously for continuous descent. Kinetic differences at the knee and ankle signify the contrasting and prominent functions of controlled lowering during the top transition and forward continuance during the bottom transition. The varying musculoskeletal demands encountered during each functional sub-task should be addressed in falls prevention programmes with elderly populations where the greatest clinical impact may be achieved. Knee extensor eccentric power through flexion exercises would facilitate a smooth transition at the top and improving ankle plantarflexion strength during single and double limb stance activities would ease the transition into level gait following continuous descent.

  1. Hardware Development and Locomotion Control Strategy for an Over-Ground Gait Trainer: NaTUre-Gaits

    PubMed Central

    Low, Kin Huat; Qu, Xingda; Lim, Hup Boon; Hoon, Kay Hiang

    2014-01-01

    Therapist-assisted body weight supported (TABWS) gait rehabilitation was introduced two decades ago. The benefit of TABWS in functional recovery of walking in spinal cord injury and stroke patients has been demonstrated and reported. However, shortage of therapists, labor-intensiveness, and short duration of training are some limitations of this approach. To overcome these deficiencies, robotic-assisted gait rehabilitation systems have been suggested. These systems have gained attentions from researchers and clinical practitioner in recent years. To achieve the same objective, an over-ground gait rehabilitation system, NaTUre-gaits, was developed at the Nanyang Technological University. The design was based on a clinical approach to provide four main features, which are pelvic motion, body weight support, over-ground walking experience, and lower limb assistance. These features can be achieved by three main modules of NaTUre-gaits: 1) pelvic assistance mechanism, mobile platform, and robotic orthosis. Predefined gait patterns are required for a robotic assisted system to follow. In this paper, the gait pattern planning for NaTUre-gaits was accomplished by an individual-specific gait pattern prediction model. The model generates gait patterns that resemble natural gait patterns of the targeted subjects. The features of NaTUre-gaits have been demonstrated by walking trials with several subjects. The trials have been evaluated by therapists and doctors. The results show that 10-m walking trial with a reduction in manpower. The task-specific repetitive training approach and natural walking gait patterns were also successfully achieved. PMID:27170876

  2. From Born Reciprocity to Reciprocal Relativity: A Paradigm for Space-Time Physics

    NASA Astrophysics Data System (ADS)

    Jarvis, Peter

    Born's principle of reciprocity -- the exchangeability of relativistic energy-momentum and time-position -- can be seen as a discrete element of a continuous group of symmetry transformations which transcend relativity. Invariance under the semi-direct product of the Weyl-Heisenberg group H(4) of canonical commutation relations with the non-compact unitary group U(3, 1) -- the so-called quaplectic group U(3, 1) ⋉ H(4) -- has been considered by Low as an extension of Born reciprocity to a fundamental symmetry principle of `reciprocal relativity' for the physics of non-inertial frames and high energy processes...

  3. The golden ratio of gait harmony: repetitive proportions of repetitive gait phases.

    PubMed

    Iosa, Marco; Fusco, Augusto; Marchetti, Fabio; Morone, Giovanni; Caltagirone, Carlo; Paolucci, Stefano; Peppe, Antonella

    2013-01-01

    In nature, many physical and biological systems have structures showing harmonic properties. Some of them were found related to the irrational number φ known as the golden ratio that has important symmetric and harmonic properties. In this study, the spatiotemporal gait parameters of 25 healthy subjects were analyzed using a stereophotogrammetric system with 25 retroreflective markers located on their skin. The proportions of gait phases were compared with φ, the value of which is about 1.6180. The ratio between the entire gait cycle and stance phase resulted in 1.620 ± 0.058, that between stance and the swing phase was 1.629 ± 0.173, and that between swing and the double support phase was 1.684 ± 0.357. All these ratios did not differ significantly from each other (F = 0.870, P = 0.422, repeated measure analysis of variance) or from φ (P = 0.670, 0.820, 0.422, resp., t-tests). The repetitive gait phases of physiological walking were found in turn in repetitive proportions with each other, revealing an intrinsic harmonic structure. Harmony could be the key for facilitating the control of repetitive walking. Harmony is a powerful unifying factor between seemingly disparate fields of nature, including human gait.

  4. The effects of gait velocity on the gait characteristics of hemiplegic patients.

    PubMed

    You, Young Youl; Chung, Sin Ho

    2015-03-01

    [Purpose] The present study investigated the effects of gait speed on temporal and spatial gait characteristics of hemiplegic stroke patients. [Subjects and Methods] Twenty post-stroke hemiplegic patients participated in the present study. To enhance the reliability of the analysis of the gait characteristics, the assessments were conducted three days per week at the same time every day. Each subject walked maintaining a comfortable speed for the first minute, and measurement was conducted for 30 seconds at a treadmill speed of 1 km/hour thereafter. Then, the subjects walked at a treadmill speed of 2 km/hour for 30 seconds after a 30-minute rest. The differences in the measurements were tested for significance using the paired t-test. [Results] The measures of foot rotation, step width, load response, mid stance, pre-swing, swing phase, and double stance phase showed significant difference between the gait velocities. [Conclusion] The present study provides basic data for gait velocity changes for hemiplegic patients.

  5. Autonomous Evolution of Dynamic Gaits with Two Quadruped Robots

    NASA Technical Reports Server (NTRS)

    Hornby, Gregory S.; Takamura, Seichi; Yamamoto, Takashi; Fujita, Masahiro

    2004-01-01

    A challenging task that must be accomplished for every legged robot is creating the walking and running behaviors needed for it to move. In this paper we describe our system for autonomously evolving dynamic gaits on two of Sony's quadruped robots. Our evolutionary algorithm runs on board the robot and uses the robot's sensors to compute the quality of a gait without assistance from the experimenter. First we show the evolution of a pace and trot gait on the OPEN-R prototype robot. With the fastest gait, the robot moves at over 10/min/min., which is more than forty body-lengths/min. While these first gaits are somewhat sensitive to the robot and environment in which they are evolved, we then show the evolution of robust dynamic gaits, one of which is used on the ERS-110, the first consumer version of AIBO.

  6. Effects of conventional overground gait training and a gait trainer with partial body weight support on spatiotemporal gait parameters of patients after stroke.

    PubMed

    Park, Byoung-Sun; Kim, Mee-Young; Lee, Lim-Kyu; Yang, Seung-Min; Lee, Won-Deok; Noh, Ji-Woong; Shin, Yong-Sub; Kim, Ju-Hyun; Lee, Jeong-Uk; Kwak, Taek-Yong; Lee, Tae-Hyun; Kim, Ju-Young; Kim, Junghwan

    2015-05-01

    [Purpose] The purpose of this study was to confirm the effects of both conventional overground gait training (CGT) and a gait trainer with partial body weight support (GTBWS) on spatiotemporal gait parameters of patients with hemiparesis following chronic stroke. [Subjects and Methods] Thirty stroke patients were alternately assigned to one of two treatment groups, and both groups underwent CGT and GTBWS. [Results] The functional ambulation classification on the affected side improved significantly in the CGT and GTBWS groups. Walking speed also improved significantly in both groups. [Conclusion] These results suggest that the GTBWS in company with CGT may be, in part, an effective method of gait training for restoring gait ability in patients after a stroke. PMID:26157272

  7. Effects of conventional overground gait training and a gait trainer with partial body weight support on spatiotemporal gait parameters of patients after stroke.

    PubMed

    Park, Byoung-Sun; Kim, Mee-Young; Lee, Lim-Kyu; Yang, Seung-Min; Lee, Won-Deok; Noh, Ji-Woong; Shin, Yong-Sub; Kim, Ju-Hyun; Lee, Jeong-Uk; Kwak, Taek-Yong; Lee, Tae-Hyun; Kim, Ju-Young; Kim, Junghwan

    2015-05-01

    [Purpose] The purpose of this study was to confirm the effects of both conventional overground gait training (CGT) and a gait trainer with partial body weight support (GTBWS) on spatiotemporal gait parameters of patients with hemiparesis following chronic stroke. [Subjects and Methods] Thirty stroke patients were alternately assigned to one of two treatment groups, and both groups underwent CGT and GTBWS. [Results] The functional ambulation classification on the affected side improved significantly in the CGT and GTBWS groups. Walking speed also improved significantly in both groups. [Conclusion] These results suggest that the GTBWS in company with CGT may be, in part, an effective method of gait training for restoring gait ability in patients after a stroke.

  8. Effects of conventional overground gait training and a gait trainer with partial body weight support on spatiotemporal gait parameters of patients after stroke

    PubMed Central

    Park, Byoung-Sun; Kim, Mee-Young; Lee, Lim-Kyu; Yang, Seung-Min; Lee, Won-Deok; Noh, Ji-Woong; Shin, Yong-Sub; Kim, Ju-Hyun; Lee, Jeong-Uk; Kwak, Taek-Yong; Lee, Tae-Hyun; Kim, Ju-Young; Kim, Junghwan

    2015-01-01

    [Purpose] The purpose of this study was to confirm the effects of both conventional overground gait training (CGT) and a gait trainer with partial body weight support (GTBWS) on spatiotemporal gait parameters of patients with hemiparesis following chronic stroke. [Subjects and Methods] Thirty stroke patients were alternately assigned to one of two treatment groups, and both groups underwent CGT and GTBWS. [Results] The functional ambulation classification on the affected side improved significantly in the CGT and GTBWS groups. Walking speed also improved significantly in both groups. [Conclusion] These results suggest that the GTBWS in company with CGT may be, in part, an effective method of gait training for restoring gait ability in patients after a stroke. PMID:26157272

  9. Locomotion gaits of a rotating cylinder pair

    NASA Astrophysics Data System (ADS)

    van Rees, Wim M.; Novati, Guido; Koumoutsakos, Petros; Mahadevan, L.

    2015-11-01

    Using 2D numerical simulations of the Navier-Stokes equations, we demonstrate that a simple pair of rotating cylinders can display a range of locomotion patterns of biological and engineering interest. Steadily counter-rotating the cylinders causes the pair to move akin to a vortex dipole for low rotation rates, but as the rotational velocity is increased the direction of motion reverses. Unsteady rotations lead to different locomotion gaits that resemble jellyfish (for in-phase rotations) and undulating swimmers (for out-of-phase rotations). The small number of parameters for this simple system allows us to systematically map the phase space of these gaits, and allows us to understand the underlying physical mechanisms using a minimal model with implications for biological locomotion and engineered analogs.

  10. An efficient robotic tendon for gait assistance.

    PubMed

    Hollander, Kevin W; Ilg, Robert; Sugar, Thomas G; Herring, Donald

    2006-10-01

    A robotic tendon is a spring based, linear actuator in which the stiffness of the spring is crucial for its successful use in a lightweight, energy efficient, powered ankle orthosis. Like its human analog, the robotic tendon uses its inherent elastic nature to reduce both peak power and energy requirements for its motor. In the ideal example, peak power required of the motor for ankle gait is reduced from 250 W to just 77 W. In addition, ideal energy requirements are reduced from nearly 36 J to just 21 J. Using this approach, an initial prototype has provided 100% of the power and energy necessary for ankle gait in a compact 0.95 kg package, seven times less than an equivalent motor/gearbox system.

  11. Treatment of gait ignition failure with ropinirole.

    PubMed

    Cohen-Oram, Alexis N; Stewart, Jonathan T; Bero, Kim; Hoffmann, Michael W

    2014-10-01

    Gait ignition failure (GIF) is a syndrome characterized by hesitation or inability to initiate gait from a static position. It may occur in a variety of conditions, including normal pressure hydrocephalus, subcortical vascular disease, parkinsonian syndromes and a variety of focal lesions. Previous information on the treatment of GIF has been primarily anecdotal, but there have been a few reports of response to dopamine agonists. We report a 63-year-old man with anoxic encephalopathy who developed GIF nine years after the initial anoxic insult. The patient's GIF responded robustly, albeit transiently, to ropinirole. MRI was unrevealing, but a positron emission tomography scan showed hypometabolism in the deep frontal ACA/MCA watershed area; this may have disconnected the basal ganglia from the motor cortex and/or interrupted dopaminergic mesocortical transmission. Our understanding of the pathophysiology and the treatment of GIF remains limited, but there may be at least a limited therapeutic role for dopamine agonists. PMID:25360234

  12. Zernike moments features for shape-based gait recognition

    NASA Astrophysics Data System (ADS)

    Qin, Huanfeng; Qin, Lan; Liu, Jun; Chao, Jiang

    2011-12-01

    The paper proposes a new spatio-temporal gait representation, called cycles gait Zernike moments (CGZM), to characterize human walking properties for individual recognition. Firstly, Zernike moments as shape descriptors are used to characterize gait silhouette shape. Secondly, we generate CGZM from Zernike moments of silhouette sequences. Finally, the phase and magnitude coefficientsof CGZM are utilized to perform classification by the modified Hausdorff distance (MHD) classifier. Experimental results show that the proposed approach have an encouraging recognition performance.

  13. 47 CFR 51.703 - Reciprocal compensation obligation of LECs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Reciprocal compensation obligation of LECs. 51.703 Section 51.703 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) INTERCONNECTION Reciprocal Compensation for Transport and Termination...

  14. Development of Trust and Reciprocity in Adolescence

    ERIC Educational Resources Information Center

    van den Bos, Wouter; Westenberg, Michiel; van Dijk, Eric; Crone, Eveline A.

    2010-01-01

    We investigate the development of two types of prosocial behavior, trust and reciprocity, as defined using a game-theoretical task that allows investigation of real-time social interaction, among 4 age groups from 9 to 25 years. By manipulating the possible outcome alternatives, we could distinguish among important determinants of trust and…

  15. Cooperation under indirect reciprocity and imitative trust.

    PubMed

    Saavedra, Serguei; Smith, David; Reed-Tsochas, Felix

    2010-10-27

    Indirect reciprocity, a key concept in behavioral experiments and evolutionary game theory, provides a mechanism that allows reciprocal altruism to emerge in a population of self-regarding individuals even when repeated interactions between pairs of actors are unlikely. Recent empirical evidence show that humans typically follow complex assessment strategies involving both reciprocity and social imitation when making cooperative decisions. However, currently, we have no systematic understanding of how imitation, a mechanism that may also generate negative effects via a process of cumulative advantage, affects cooperation when repeated interactions are unlikely or information about a recipient's reputation is unavailable. Here we extend existing evolutionary models, which use an image score for reputation to track how individuals cooperate by contributing resources, by introducing a new imitative-trust score, which tracks whether actors have been the recipients of cooperation in the past. We show that imitative trust can co-exist with indirect reciprocity mechanisms up to a threshold and then cooperation reverses -revealing the elusive nature of cooperation. Moreover, we find that when information about a recipient's reputation is limited, trusting the action of third parties towards her (i.e. imitating) does favor a higher collective cooperation compared to random-trusting and share-alike mechanisms. We believe these results shed new light on the factors favoring social imitation as an adaptive mechanism in populations of cooperating social actors.

  16. Upstream reciprocity and the evolution of gratitude.

    PubMed

    Nowak, Martin A; Roch, Sébastien

    2007-03-01

    If someone is nice to you, you feel good and may be inclined to be nice to somebody else. This every day experience is borne out by experimental games: the recipients of an act of kindness are more likely to help in turn, even if the person who benefits from their generosity is somebody else. This behaviour, which has been called 'upstream reciprocity', appears to be a misdirected act of gratitude: you help somebody because somebody else has helped you. Does this make any sense from an evolutionary or a game theoretic perspective? In this paper, we show that upstream reciprocity alone does not lead to the evolution of cooperation, but it can evolve and increase the level of cooperation if it is linked to either direct or spatial reciprocity. We calculate the random walks of altruistic acts that are induced by upstream reciprocity. Our analysis shows that gratitude and other positive emotions, which increase the willingness to help others, can evolve in the competitive world of natural selection.

  17. Weak reciprocity alone cannot explain peer punishment.

    PubMed

    Casari, Marco

    2012-02-01

    The claims about (1) the lack of empirical support for a model of strong reciprocation and (2) the irrelevant empirical role of costly punishment to support cooperation in the field need qualifications. The interpretation of field evidence is not straightforward, and other-regarding preferences are also likely to play a role in the field.

  18. The Effects of Feedback as Interpersonal Reciprocities

    ERIC Educational Resources Information Center

    Levenstein, Joseph; And Others

    1977-01-01

    Tests the hypothesis that a response to a given feedback statement will be its reciprocal. In Phase 1, a pool of feedback statements was written and scaled along dimensions of power (dominance-submission) and affect (affection-hostility). In Phase 2, these statements were used as the basis for giving feedback and replying to it. (Author)

  19. 36 CFR 251.63 - Reciprocity.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 251.63 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE LAND USES Special Uses § 251.63 Reciprocity. If it is determined that a right-of-way shall be needed by the United States... across Federal lands, the authorized officer may condition a special use authorization to require...

  20. 36 CFR 251.63 - Reciprocity.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 251.63 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE LAND USES Special Uses § 251.63 Reciprocity. If it is determined that a right-of-way shall be needed by the United States... across Federal lands, the authorized officer may condition a special use authorization to require...

  1. 36 CFR 251.63 - Reciprocity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 251.63 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE LAND USES Special Uses § 251.63 Reciprocity. If it is determined that a right-of-way shall be needed by the United States... across Federal lands, the authorized officer may condition a special use authorization to require...

  2. 36 CFR 251.63 - Reciprocity.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 251.63 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE LAND USES Special Uses § 251.63 Reciprocity. If it is determined that a right-of-way shall be needed by the United States... across Federal lands, the authorized officer may condition a special use authorization to require...

  3. 36 CFR 251.63 - Reciprocity.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 251.63 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE LAND USES Special Uses § 251.63 Reciprocity. If it is determined that a right-of-way shall be needed by the United States... across Federal lands, the authorized officer may condition a special use authorization to require...

  4. 46 CFR 8.120 - Reciprocity.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... § 8.120 Reciprocity. (a) The Commandant may delegate authority to a classification society that has... in paragraph (a) of this section are satisfied, a classification society must provide to the Coast Guard an affidavit, from the government of the country that the classification society is...

  5. 46 CFR 8.120 - Reciprocity.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... § 8.120 Reciprocity. (a) The Commandant may delegate authority to a classification society that has... in paragraph (a) of this section are satisfied, a classification society must provide to the Coast Guard an affidavit, from the government of the country that the classification society is...

  6. Reciprocity in Preschool Peers' Social Interaction.

    ERIC Educational Resources Information Center

    Chiu, Jih-Perng Peter

    This study sought to describe the norms of reciprocity in social interaction from the viewpoint of immediate behavioral exchanges by examining the social interaction of preschool peers in a free-play situation. Seventeen 4-year-old children, eight girls and nine boys, were observed during free play activity periods after a picture sociometric test…

  7. 37 CFR 11.24 - Reciprocal discipline.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... case by clear and convincing evidence that the practitioner violated 37 CFR 10.23, as further identified under 37 CFR 10.23(c)(5), (or any successor regulation identifying such public censure, public... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Reciprocal discipline....

  8. 37 CFR 11.24 - Reciprocal discipline.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... case by clear and convincing evidence that the practitioner violated 37 CFR 10.23, as further identified under 37 CFR 10.23(c)(5), (or any successor regulation identifying such public censure, public... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Reciprocal discipline....

  9. 37 CFR 11.24 - Reciprocal discipline.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2014-07-01 2014-07-01 false Reciprocal discipline. 11.24... discipline. (a) Notification of OED Director. Within thirty days of being publicly censured, publicly... USPTO Director. The OED Director shall, in addition, without Committee on Discipline authorization,...

  10. 37 CFR 11.24 - Reciprocal discipline.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... case by clear and convincing evidence that the practitioner violated 37 CFR 10.23, as further identified under 37 CFR 10.23(c)(5), (or any successor regulation identifying such public censure, public... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Reciprocal discipline....

  11. 37 CFR 11.24 - Reciprocal discipline.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2013-07-01 2013-07-01 false Reciprocal discipline. 11.24... discipline. (a) Notification of OED Director. Within thirty days of being publicly censured, publicly... USPTO Director. The OED Director shall, in addition, without Committee on Discipline authorization,...

  12. Tuition Reciprocity in the United States

    ERIC Educational Resources Information Center

    Stewart, Gregory; Wright, Dianne Brown; Kennedy, Angelica

    2008-01-01

    Reciprocity agreements are contracts between two or more parties whereby students pay reduced tuition rates. The rate of reduction is determined by the parameters set forth in each individual state's agreement but may range from a modest reduction in fees to a waiver of full non-resident tuition. In addition to providing tuition relief,…

  13. Gait patterns for crime fighting: statistical evaluation

    NASA Astrophysics Data System (ADS)

    Sulovská, Kateřina; Bělašková, Silvie; Adámek, Milan

    2013-10-01

    The criminality is omnipresent during the human history. Modern technology brings novel opportunities for identification of a perpetrator. One of these opportunities is an analysis of video recordings, which may be taken during the crime itself or before/after the crime. The video analysis can be classed as identification analyses, respectively identification of a person via externals. The bipedal locomotion focuses on human movement on the basis of their anatomical-physiological features. Nowadays, the human gait is tested by many laboratories to learn whether the identification via bipedal locomotion is possible or not. The aim of our study is to use 2D components out of 3D data from the VICON Mocap system for deep statistical analyses. This paper introduces recent results of a fundamental study focused on various gait patterns during different conditions. The study contains data from 12 participants. Curves obtained from these measurements were sorted, averaged and statistically tested to estimate the stability and distinctiveness of this biometrics. Results show satisfactory distinctness of some chosen points, while some do not embody significant difference. However, results presented in this paper are of initial phase of further deeper and more exacting analyses of gait patterns under different conditions.

  14. Gait Recognition and Walking Exercise Intensity Estimation

    PubMed Central

    Lin, Bor-Shing; Liu, Yu-Ting; Yu, Chu; Jan, Gene Eu; Hsiao, Bo-Tang

    2014-01-01

    Cardiovascular patients consult doctors for advice regarding regular exercise, whereas obese patients must self-manage their weight. Because a system for permanently monitoring and tracking patients’ exercise intensities and workouts is necessary, a system for recognizing gait and estimating walking exercise intensity was proposed. For gait recognition analysis, αβ filters were used to improve the recognition of athletic attitude. Furthermore, empirical mode decomposition (EMD) was used to filter the noise of patients’ attitude to acquire the Fourier transform energy spectrum. Linear discriminant analysis was then applied to this energy spectrum for training and recognition. When the gait or motion was recognized, the walking exercise intensity was estimated. In addition, this study addressed the correlation between inertia and exercise intensity by using the residual function of the EMD and quadratic approximation to filter the effect of the baseline drift integral of the acceleration sensor. The increase in the determination coefficient of the regression equation from 0.55 to 0.81 proved that the accuracy of the method for estimating walking exercise intensity proposed by Kurihara was improved in this study. PMID:24714057

  15. Gait Signal Analysis with Similarity Measure

    PubMed Central

    Shin, Seungsoo

    2014-01-01

    Human gait decision was carried out with the help of similarity measure design. Gait signal was selected through hardware implementation including all in one sensor, control unit, and notebook with connector. Each gait signal was considered as high dimensional data. Therefore, high dimensional data analysis was considered via heuristic technique such as the similarity measure. Each human pattern such as walking, sitting, standing, and stepping up was obtained through experiment. By the results of the analysis, we also identified the overlapped and nonoverlapped data relation, and similarity measure analysis was also illustrated, and comparison with conventional similarity measure was also carried out. Hence, nonoverlapped data similarity analysis provided the clue to solve the similarity of high dimensional data. Considered high dimensional data analysis was designed with consideration of neighborhood information. Proposed similarity measure was applied to identify the behavior patterns of different persons, and different behaviours of the same person. Obtained analysis can be extended to organize health monitoring system for specially elderly persons. PMID:25110724

  16. Gait kinematic analysis evaluates hindlimb revascularization.

    PubMed

    Ríos, Amelia; Delgado, Alexandra; Escalante, Bruno; Santana, Jesús

    2011-01-01

    Peripheral arterial occlusive disease is described as vascular disorders associated with ischemia and may be the result of an obstructive vascular process or a lost revascularization response. We have shown that gait locomotion analysis by video filming represents an integrative model for the evaluation of mechanisms involved in the process of ischemia-induced revascularization. However, analysis by this method can be subjective and perception errors may be occurring. We present the optimization of a quantifiable, noninvasive, reproducible method that analyzes ankle kinematics in rats using a two-dimensional digital video system. Gait dynamics were filmed in hindlimb ischemic rats with a high speed digital video camera. Images were collected and analyzed at 125 frames per second. An algorithm using interactive data language (IDL) was devised to assess different parameters. In ischemic rats, stride time and knee joint angle remained altered 10 days post-surgery compared with sham animals. Gait kinematics were outlined in a highly reliable way by this computational analysis and corroborated the notion of hindlimb movement recovery associated with the revascularization process.

  17. Recovery of gait after quadriceps muscle fatigue.

    PubMed

    Barbieri, Fabio Augusto; Beretta, Stephannie Spiandor; Pereira, Vinicius A I; Simieli, Lucas; Orcioli-Silva, Diego; dos Santos, Paulo Cezar Rocha; van Dieën, Jaap H; Gobbi, Lilian Teresa Bucken

    2016-01-01

    The aim of this study was to investigate the effect of recovery time after quadriceps muscle fatigue on gait in young adults. Forty young adults (20-40 years old) performed three 8-m gait trials at preferred velocity before and after muscle fatigue, and after 5, 10 and 20min of passive rest. In addition, at each time point, two maximal isometric voluntary contractions were preformed. Muscle fatigue was induced by repeated sit-to-stand transfers until task failure. Spatio-temporal, kinetic and muscle activity parameters, measured in the central stride of each trial, were analyzed. Data were compared between before and after the muscle fatigue protocol and after the recovery periods by one-way repeated measures ANOVA. The voluntary force was decreased after the fatigue protocol (p<0.001) and after 5, 10 and 20min of recovery compared to before the fatigue protocol. Step width (p<0.001) and RMS of biceps femoris (p<0.05) were increased immediately after the fatigue protocol and remained increased after the recovery periods. In addition, stride duration was decreased immediately after the fatigue protocol compared to before and to after 10 and 20min of rest (p<0.001). The anterior-posterior propulsive impulse was also decreased after the fatigue protocol (p<0.001) and remained low after 5, 10 and 20min of rest. We conclude that 20min is not enough to see full recovery of gait after exhaustive quadriceps muscle fatigue.

  18. Fractional Langevin model of gait variability

    PubMed Central

    West, Bruce J; Latka, Miroslaw

    2005-01-01

    The stride interval in healthy human gait fluctuates from step to step in a random manner and scaling of the interstride interval time series motivated previous investigators to conclude that this time series is fractal. Early studies suggested that gait is a monofractal process, but more recent work indicates the time series is weakly multifractal. Herein we present additional evidence for the weakly multifractal nature of gait. We use the stride interval time series obtained from ten healthy adults walking at a normal relaxed pace for approximately fifteen minutes each as our data set. A fractional Langevin equation is constructed to model the underlying motor control system in which the order of the fractional derivative is itself a stochastic quantity. Using this model we find the fractal dimension for each of the ten data sets to be in agreement with earlier analyses. However, with the present model we are able to draw additional conclusions regarding the nature of the control system guiding walking. The analysis presented herein suggests that the observed scaling in interstride interval data may not be due to long-term memory alone, but may, in fact, be due partly to the statistics. PMID:16076394

  19. Functional distance in human gait transition.

    PubMed

    Abdolvahab, Mohammad; Carello, Claudia

    2015-10-01

    The emerging understanding of the behavioral transitions that accompany the ascending and descending method of limits is in terms of "functional distance" - the degree to which a perceiver is disengaged from ordinary exploratory activities. Increasing functional distance results in negative hysteresis in contrast to the classical positive hysteresis more typical of ongoing activity. In the present study of human gait transitions on a treadmill, the functional distance between a perceiver and ordinary exploratory activities was manipulated in two ways: (1) "Active" participants, walking or running on a treadmill, were asked to anticipate the gait that would be required if treadmill speed were increased or decreased; and (2) "passive" participants, standing off a moving treadmill, were asked to report the gait they would use if they were on the treadmill at its current speed. As expected, the increase of functional distance from (1) to (2) reduced the amount of classical hysteresis and promoted negative hysteresis, that is, a lower transition speed for walk-to-run transitions (ascending trials) than for run-to-walk transitions (descending trials). These results complement empirical findings in other behavioral transition experiments. More broadly, they signify the role of perception-action cycles for grounding natural on-going perception. In particular, they support the assertion that perception and action are intertwined and that lack of information about an impending action has consequences for perceptual judgments. PMID:26408863

  20. Gait patterns after anterior cruciate ligament reconstruction.

    PubMed

    Bulgheroni, P; Bulgheroni, M V; Andrini, L; Guffanti, P; Giughello, A

    1997-01-01

    The aim of this study is to analyse the changes in select gait parameters following anterior cruciate ligament (ACL) reconstruction. The study was performed on 15 subjects who underwent ACL reconstruction by the bone-patellar tendon-bone technique. Gait analysis was performed using the Elite three-dimensional (3D) optoelectronic system (BTS), a Kistler force platform and the Telemg telemetric electromyograph (BTS). Kinematic data were recorded for the principal lower limb joints (hip, knee and ankle). The examined muscles include vastus lateralis, rectus femoris, biceps femoris and semitendinosus. The results obtained from the operated subjects were compared with those of 10 untreated subjects and 5 subjects without ACL damage. In the operated subjects the knee joint angular values regained a normal flexion pattern for the injured limb during the stance phase. The analysis of joint moments shows: (a) sagittal plane: recovery of the knee flexion moment at loading response and during preswing; (b) frontal plane: recovery of the normal patterns for both hip and knee adduction-abduction moments during the entire stance phase. The examination of ground reaction forces reveals the recovery of frontal component features. The EMG traces show the normal biphasic pattern for the operated subjects as compared to the untreated subjects. The results suggest that the gait parameters shift towards normal value patterns.

  1. Gait correlation analysis based human identification.

    PubMed

    Chen, Jinyan

    2014-01-01

    Human gait identification aims to identify people by a sequence of walking images. Comparing with fingerprint or iris based identification, the most important advantage of gait identification is that it can be done at a distance. In this paper, silhouette correlation analysis based human identification approach is proposed. By background subtracting algorithm, the moving silhouette figure can be extracted from the walking images sequence. Every pixel in the silhouette has three dimensions: horizontal axis (x), vertical axis (y), and temporal axis (t). By moving every pixel in the silhouette image along these three dimensions, we can get a new silhouette. The correlation result between the original silhouette and the new one can be used as the raw feature of human gait. Discrete Fourier transform is used to extract features from this correlation result. Then, these features are normalized to minimize the affection of noise. Primary component analysis method is used to reduce the features' dimensions. Experiment based on CASIA database shows that this method has an encouraging recognition performance. PMID:24592144

  2. Detection of abnormalities in a human gait using smart shoes

    NASA Astrophysics Data System (ADS)

    Kong, Kyoungchul; Bae, Joonbum; Tomizuka, Masayoshi

    2008-03-01

    Health monitoring systems require a means for detecting and quantifying abnormalities from measured signals. In this paper, a new method for detecting abnormalities in a human gait is proposed for an improved gait monitoring system for patients with walking problems. In the previous work, we introduced a fuzzy logic algorithm for detecting phases in a human gait based on four foot pressure sensors for each of the right and left foot. The fuzzy logic algorithm detects the gait phases smoothly and continuously, and retains all information obtained from sensors. In this paper, a higher level algorithm for detecting abnormalities in the gait phases obtained from the fuzzy logic is discussed. In the proposed algorithm, two major abnormalities are detected 1) when the sensors measure improper foot pressure patterns, and 2) when the human does not follow a natural sequence of gait phases. For mathematical realization of the algorithm, the gait phases are dealt with by a vector analysis method. The proposed detection algorithm is verified by experiments on abnormal gaits as well as normal gaits. The experiment makes use of the Smart Shoes that embeds four bladders filled with air, the pressure changes in which are detected by pressure transducers.

  3. Enhanced data consistency of a portable gait measurement system

    NASA Astrophysics Data System (ADS)

    Lin, Hsien-I.; Chiang, Y. P.

    2013-11-01

    A gait measurement system is a useful tool for rehabilitation applications. Such a system is used to conduct gait experiments in large workplaces such as laboratories where gait measurement equipment can be permanently installed. However, a gait measurement system should be portable if it is to be used in clinics or community centers for aged people. In a portable gait measurement system, the workspace is limited and landmarks on a subject may not be visible to the cameras during experiments. Thus, we propose a virtual-marker function to obtain positions of unseen landmarks for maintaining data consistency. This work develops a portable clinical gait measurement system consisting of lightweight motion capture devices, force plates, and a walkway assembled from plywood boards. We evaluated the portable clinic gait system with 11 normal subjects in three consecutive days in a limited experimental space. Results of gait analysis based on the verification of within-day and between-day coefficients of multiple correlations show that the proposed portable gait system is reliable.

  4. Dynamic Principles of Gait and Their Clinical Implications

    PubMed Central

    Donelan, J. Maxwell

    2010-01-01

    A healthy gait pattern depends on an array of biomechanical features, orchestrated by the central nervous system for economy and stability. Injuries and other pathologies can alter these features and result in substantial gait deficits, often with detrimental consequences for energy expenditure and balance. An understanding of the role of biomechanics in the generation of healthy gait, therefore, can provide insight into these deficits. This article examines the basic principles of gait from the standpoint of dynamic walking, an approach that combines an inverted pendulum model of the stance leg with a pendulum model of the swing leg and its impact with the ground. The heel-strike at the end of each step has dynamic effects that can contribute to a periodic gait and its passive stability. Biomechanics, therefore, can account for much of the gait pattern, with additional motor inputs that are important for improving economy and stability. The dynamic walking approach can predict the consequences of disruptions to normal biomechanics, and the associated observations can help explain some aspects of impaired gait. This article reviews the basic principles of dynamic walking and the associated experimental evidence for healthy gait and then considers how the principles may be applied to clinical gait pathologies. PMID:20023002

  5. Cognitive contributions to gait and falls: evidence and implications.

    PubMed

    Amboni, Marianna; Barone, Paolo; Hausdorff, Jeffrey M

    2013-09-15

    Dementia and gait impairments often coexist in older adults and patients with neurodegenerative disease. Both conditions represent independent risk factors for falls. The relationship between cognitive function and gait has recently received increasing attention. Gait is no longer considered merely automated motor activity but rather an activity that requires executive function and attention as well as judgment of external and internal cues. In this review, we intend to: (1) summarize and synthesize the experimental, neuropsychological, and neuroimaging evidence that supports the role played by cognition in the control of gait; and (2) briefly discuss the implications deriving from the interplay between cognition and gait. In recent years, the dual task paradigm has been widely used as an experimental method to explore the interplay between gait and cognition. Several neuropsychological investigations have also demonstrated that walking relies on the use of several cognitive domains, including executive-attentional function, visuospatial abilities, and even memory resources. A number of morphological and functional neuroimaging studies have offered additional evidence supporting the relationship between gait and cognitive resources. Based on the findings from 3 lines of studies, it appears that a growing body of evidence indicates a pivotal role of cognition in gait control and fall prevention. The interplay between higher-order neural function and gait has a number of clinical implications, ranging from integrated assessment tools to possible innovative lines of interventions, including cognitive therapy for falls prevention on one hand and walking program for reducing dementia risk on the other.

  6. [Quantitative gait analysis in patients with advanced Parkinson's disease].

    PubMed

    Villadoniga, M; San Millan, A; Cabanes-Martinez, L; Aviles-Olmos, I; Del Alamo-De Pedro, M; Regidor, I

    2016-08-01

    Objetivo. Describir las alteraciones de la marcha e inestabilidad postural en un grupo de pacientes con enfermedad de Parkinson (EP) avanzada. Pacientes y metodos. Se analizo la marcha de pacientes con EP en estadio avanzado on medicacion. Por medio de un sistema de analisis computarizado del movimiento, se estudiaron las variables cinematicas: cadencia, numero de ciclos con apoyo correcto (ciclos HFPS), numero de ciclos totales, duracion de las fases del ciclo, electromiografia, y goniometria de rodilla y tobillo. La valoracion clinica del equilibrio y la inestabilidad postural se completo con los tests Tinetti y Timed Up and Go. Resultados. El analisis mostro alteraciones en los parametros espaciotemporales con respecto a los rangos de normalidad: disminucion de los ciclos HFPS, aumento del numero total de ciclos y alteracion de la cadencia en muchos pacientes, y conservacion de la cadencia media dentro de los limites de la normalidad, aumento de la duracion de la fase de apoyo, disminucion del apoyo monopodal y alteracion del rango articular de la rodilla y el tobillo. Asimismo, se observo una alteracion en las puntuaciones obtenidas en las escalas clinicas, que mostraban un aumento del factor de riesgo de caidas y dependencia leve. Conclusion. La cuantificacion mediante analisis objetivo de las variables cineticas y cinematicas en los pacientes con EP puede emplearse como herramienta para establecer la influencia de las distintas alternativas terapeuticas en el trastorno de la marcha.

  7. Substrates for normal gait and pathophysiology of gait disturbances with respect to the basal ganglia dysfunction.

    PubMed

    Takakusaki, Kaoru; Tomita, Nozomi; Yano, Masafumi

    2008-08-01

    In this review, we have tried to elucidate substrates for the execution of normal gait and to understand pathophysiological mechanisms of gait failure in basal ganglia dysfunctions. In Parkinson's disease, volitional and emotional expressions of movement processes are seriously affected in addition to the disturbance of automatic movement processes, such as adjustment of postural muscle tone before gait initiation and rhythmic limb movements during walking. These patients also suffer from muscle tone rigidity and postural instability, which may also cause reduced walking capabilities in adapting to various environments. Neurophysiological and clinical studies have suggested the importance of basal ganglia connections with the cerebral cortex and limbic system in the expression of volitional and emotional behaviors. Here we hypothesize a crucial role played by the basal ganglia-brainstem system in the integrative control of muscle tone and locomotion. The hypothetical model may provide a rational explanation for the role of the basal ganglia in the control of volitional and automatic aspects of movements. Moreover, it might also be beneficial for understanding pathophysiological mechanisms of basal ganglia movement disorders. A part of this hypothesis has been supported by studies utilizing a constructive simulation engineering technique that clearly shows that an appropriate level of postural muscle tone and proper acquisition and utilization of sensory information are essential to maintain adaptable bodily functions for the full execution of bipedal gait. In conclusion, we suggest that the major substrates for supporting bipedal posture and executing bipedal gait are 1) fine neural networks such as the cortico-basal ganglia loop and basal ganglia-brainstem system, 2) fine musculoskeletal structures with adequately developed (postural) muscle tone, and 3) proper sensory processing. It follows that any dysfunction of the above sensorimotor integration processes

  8. Apolipoprotein E Genotype Linked to Spatial Gait Characteristics: Predictors of Cognitive Dual Task Gait Change

    PubMed Central

    MacAulay, Rebecca K.; Allaire, Ted; Brouillette, Robert; Foil, Heather; Bruce-Keller, Annadora J.; Keller, Jeffrey N.

    2016-01-01

    Background Developing measures to detect preclinical Alzheimer’s Disease is vital, as prodromal stage interventions may prove more efficacious in altering the disease’s trajectory. Gait changes may serve as a useful clinical heuristic that precedes cognitive decline. This study provides the first systematic investigation of gait characteristics relationship with relevant demographic, physical, genetic (Apolipoprotein E genotype), and health risk factors in non-demented older adults during a cognitive-load dual task walking condition. Methods The GAITRite system provided objective measurement of gait characteristics in APOE-e4 “carriers” (n = 75) and “non-carriers” (n = 224). Analyses examined stride length and step time gait characteristics during simple and dual-task (spelling five-letter words backwards) conditions in relation to demographic, physical, genetic, and health risk factors. Results Slower step time and shorter stride length associated with older age, greater health risk, and worse physical performance (ps < .05). Men and women differed in height, gait characteristics, health risk factors and global cognition (ps < .05). APOE-e4 associated with a higher likelihood of hypercholesterolemia and overall illness index scores (ps < .05). No genotype-sex interactions on gait were found. APOE-e4 was linked to shorter stride length and greater dual-task related disturbances in stride length. Conclusions Stride length has been linked to heightened fall risk, attention decrements and structural brain changes in older adults. Our results indicate that stride length is a useful behavioral marker of cognitive change that is associated with genetic risk for AD. Sex disparities in motor decline may be a function of health risk factors. PMID:27486898

  9. Reciprocal Relationships between Attitude toward Mathematics and Achievement in Mathematics.

    ERIC Educational Resources Information Center

    Ma, Xin

    1997-01-01

    This study examined reciprocal relationships between attitude toward mathematics and mathematics achievement. High school seniors from the Dominican Republic completed mathematics achievement tests and a questionnaire on mathematics attitudes. Results indicated that reciprocal relationships existed, suggesting that the reciprocal nature between…

  10. 30 CFR 56.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Reciprocating-type air compressors. 56.13010... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13010 Reciprocating-type air compressors. (a) Reciprocating-type air...

  11. 30 CFR 56.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Reciprocating-type air compressors. 56.13010... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13010 Reciprocating-type air compressors. (a) Reciprocating-type air...

  12. 30 CFR 56.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Reciprocating-type air compressors. 56.13010... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13010 Reciprocating-type air compressors. (a) Reciprocating-type air...

  13. Familial Reciprocity and Subjective Well-Being in Ghana

    ERIC Educational Resources Information Center

    Tsai, Ming-Chang; Dzorgbo, Dan-Bright S.

    2012-01-01

    The authors investigated variations in reciprocity and the impact of reciprocity on well-being in a West African society. They hypothesized that household size and income diversity encourage reciprocity, which in turn enhances subjective well-being. In empirical testing of these hypotheses the authors used the data of the Core Welfare Indicators…

  14. 47 CFR 51.711 - Symmetrical reciprocal compensation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Symmetrical reciprocal compensation. 51.711... (CONTINUED) INTERCONNECTION Reciprocal Compensation for Transport and Termination of Telecommunications Traffic § 51.711 Symmetrical reciprocal compensation. (a) Rates for transport and termination...

  15. Short-Term Reciprocity in Late Parent-Child Relationships

    ERIC Educational Resources Information Center

    Leopold, Thomas; Raab, Marcel

    2011-01-01

    Long-term concepts of parent-child reciprocity assume that the amount of support given and received is only balanced in a generalized fashion over the life course. We argue that reciprocity in parent-child relationships also operates in the short term. Our analysis of short-term reciprocity focuses on concurrent exchange in its main upward and…

  16. Effects of Physical Exercise Interventions on Gait-Related Dual-Task Interference in Older Adults: A Systematic Review and Meta-Analysis.

    PubMed

    Plummer, Prudence; Zukowski, Lisa A; Giuliani, Carol; Hall, Amber M; Zurakowski, David

    2015-01-01

    exercise interventions can improve dual-task walking in older adults primarily by increasing the speed at which individuals walk in dual-task conditions. Currently, evidence concerning whether physical exercise interventions reduce DTC or alter the self-selected dual-task strategy during unobstructed walking is greatly lacking, mainly due to the failure of studies to measure and report reciprocal dual-task effects on the non-gait task.

  17. Quantitative Gait Measurement With Pulse-Doppler Radar for Passive In-Home Gait Assessment

    PubMed Central

    Skubic, Marjorie; Rantz, Marilyn; Cuddihy, Paul E.

    2014-01-01

    In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the other at torso level is necessary. An excellent absolute agreement with intraclass correlation coefficients of 0.97 was found for step time estimation with the foot level radar. For walking speed, although both radars show excellent consistency they all have a system offset compared to the ground truth due to walking direction with respect to the radar beam. The torso level radar has a better performance (9% offset on average) in the speed estimation compared to the foot level radar (13%–18% offset). Quantitative analysis has been performed to compute the angles causing the systematic error. These lab results demonstrate the capability of the system to be used as a daily gait assessment tool in home environments, useful for fall risk assessment and other health care applications. The system is currently being tested in an unstructured home environment. PMID:24771566

  18. Quantitative gait measurement with pulse-Doppler radar for passive in-home gait assessment.

    PubMed

    Wang, Fang; Skubic, Marjorie; Rantz, Marilyn; Cuddihy, Paul E

    2014-09-01

    In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the other at torso level is necessary. An excellent absolute agreement with intraclass correlation coefficients of 0.97 was found for step time estimation with the foot level radar. For walking speed, although both radars show excellent consistency they all have a system offset compared to the ground truth due to walking direction with respect to the radar beam. The torso level radar has a better performance (9% offset on average) in the speed estimation compared to the foot level radar (13%-18% offset). Quantitative analysis has been performed to compute the angles causing the systematic error. These lab results demonstrate the capability of the system to be used as a daily gait assessment tool in home environments, useful for fall risk assessment and other health care applications. The system is currently being tested in an unstructured home environment.

  19. Quantitative gait measurement with pulse-Doppler radar for passive in-home gait assessment.

    PubMed

    Wang, Fang; Skubic, Marjorie; Rantz, Marilyn; Cuddihy, Paul E

    2014-09-01

    In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the other at torso level is necessary. An excellent absolute agreement with intraclass correlation coefficients of 0.97 was found for step time estimation with the foot level radar. For walking speed, although both radars show excellent consistency they all have a system offset compared to the ground truth due to walking direction with respect to the radar beam. The torso level radar has a better performance (9% offset on average) in the speed estimation compared to the foot level radar (13%-18% offset). Quantitative analysis has been performed to compute the angles causing the systematic error. These lab results demonstrate the capability of the system to be used as a daily gait assessment tool in home environments, useful for fall risk assessment and other health care applications. The system is currently being tested in an unstructured home environment. PMID:24771566

  20. Experimental realization of optomechanically induced non-reciprocity

    NASA Astrophysics Data System (ADS)

    Shen, Zhen; Zhang, Yan-Lei; Chen, Yuan; Zou, Chang-Ling; Xiao, Yun-Feng; Zou, Xu-Bo; Sun, Fang-Wen; Guo, Guang-Can; Dong, Chun-Hua

    2016-10-01

    Non-reciprocal devices, such as circulators and isolators, are indispensable components in classical and quantum information processing in integrated photonic circuits. Aside from these applications, the non-reciprocal phase shift is of fundamental interest for exploring exotic topological photonics, such as the realization of chiral edge states and topological protection. However, incorporating low-optical-loss magnetic materials into a photonic chip is technically challenging. In this study we experimentally demonstrate non-magnetic non-reciprocity using optomechanical interactions in a whispering gallery microresonator, as proposed in a previous work. Optomechanically induced non-reciprocal transparency and amplification are observed and a non-reciprocal phase shift of up to 40° is also demonstrated. The underlying mechanism of optomechanically induced non-reciprocity has great potential for all-optical controllable isolators and circulators, as well as non-reciprocal phase shifters in integrated photonic chips.

  1. Condition monitoring of reciprocating seal based on FBG sensors

    NASA Astrophysics Data System (ADS)

    Zhao, Xiuxu; Zhang, Shuanshuan; Wen, Pengfei; Zhen, Wenhan; Ke, Wei

    2016-07-01

    The failure of hydraulic reciprocating seals will seriously affect the normal operation of hydraulic reciprocating machinery, so the potential fault condition monitoring of reciprocating seals is very important. However, it is extremely difficult because of the limitation of reciprocating motion and the structure constraints of seal groove. In this study, an approach using fiber Bragg grating (FBG) sensors is presented. Experimental results show that the contact strain changes of a reciprocating seal can be detected by FBG sensors in the operation process of the hydraulic cylinders. The failure condition of the reciprocating seal can be identified by wavelet packet energy entropy, and the center frequency of power spectrum analysis. It can provide an effective solution for the fault prevention and health management of reciprocating hydraulic rod seals.

  2. Factors Related to Gait Function in Post-stroke Patients

    PubMed Central

    Cho, Ki Hun; Lee, Joo Young; Lee, Kun Jae; Kang, Eun Kyoung

    2014-01-01

    [Purpose] Gait function after a stroke is an important factor for determining a patient’s ability to independently perform activities of daily living (ADL). The objective of this study was to elucidate the factors associated with gait function in post-stroke patients. [Subjects] Thirty-nine stroke patients (16 females and 23 males; average age 67.82 ± 10.96 years; post-onset duration: 200.18 ± 27.14 days) participated in this study. [Methods] Their gait function, motor function (Manual Muscle Test [MMT] and Brünnstrom stage), level of cognition (Mini-Mental State Examination score [MMSE], and the Loewenstein Occupational Therapy Cognitive Assessment for the Geriatric Population [LOTCA-G]), and ADL (Korean modified Barthel index [K-MBI]) were assessed. [Results] The degree of gait function showed significant positive correlations with the following variables: MMT of the elbow, knee, ankle and wrist; Brünnstrom stage; MMSE; LOTCA-G subscores except motor praxis; K-MBI. Stepwise linear regression analysis revealed the Brünnstrom stage was the only explanatory variable closely associated with gait level. [Conclusion] Gait function of post-stroke patients was related to motor function, cognition, and ADL. In particular, there is a significant association between gait level and the Brünnstrom stages, reflecting the importance of monitoring the motor recovery of gait function in post-stroke patients. PMID:25540503

  3. DRAG: a database for recognition and analasys of gait

    NASA Astrophysics Data System (ADS)

    Kuchi, Prem; Hiremagalur, Raghu Ram V.; Huang, Helen; Carhart, Michael; He, Jiping; Panchanathan, Sethuraman

    2003-11-01

    A novel approach is proposed for creating a standardized and comprehensive database for gait analysis. The field of gait analysis is gaining increasing attention for applications such as visual surveillance, human-computer interfaces, and gait recognition and rehabilitation. Numerous algorithms have been developed for analyzing and processing gait data; however, a standard database for their systematic evaluation does not exist. Instead, existing gait databases consist of subsets of kinematic, kinetic, and electromyographic activity recordings by different investigators, at separate laboratories, and under varying conditions. Thus, the existing databases are neither homogenous nor sufficiently populated to statistically validate the algorithms. In this paper, a methodology for creating a database is presented, which can be used as a common ground to test the performance of algorithms that rely upon external marker data, ground reaction loading data, and/or video images. The database consists of: (1) synchronized motion-capture data (3D marker data) obtained using external markers, (2) computed joint angles, and (3) ground reaction loading acquired with plantar pressure insoles. This database could be easily expanded to include synchronized video, which will facilitate further development of video-based algorithms for motion tracking. This eventually could lead to the realization of markerless gait tracking. Such a system would have extensive applications in gait recognition, as well as gait rehabilitation. The entire database (marker, angle, and force data) will be placed in the public domain, and made available for downloads over the World Wide Web.

  4. Dependence of gait parameters on height in typically developing children.

    PubMed

    Agostini, Valentina; Nascimbeni, Alberto; Di Nardo, Francesco; Fioretti, Sandro; Burattini, Laura; Knaflitz, Marco

    2015-01-01

    In clinical gait analysis is fundamental to have access to normative data, to be used as a reference in the interpretation of pathological walking. In a paediatric population this may be complicated by the dependence of gait parameters on child growth. The aim of this work is to provide the correlations of spatial-temporal gait parameters with children's height. We obtained the regression lines of cadence, double support, and gait phases, with respect to height, from a sample of 85 normally typically developing children aged 6 to 11. Our analysis of gait phases was not limited to the traditional analysis of stance and swing, but rather focused on the sub-phases of stance - heel contact, flat foot contact, push off - which proved to be an innovative approach to gait analysis. Heel contact decreased, flat foot contact increased and push off remained essentially unchanged with respect to children's height. These results may be useful in the interpretation of gait data in developing children, and the regression lines obtained may be used to normalize their gait parameters.

  5. Effect of a textured insole on balance and gait symmetry.

    PubMed

    Aruin, Alexander S; Kanekar, Neeta

    2013-11-01

    Asymmetry of standing balance and gait is common in individuals with neurological disorders, and achieving symmetrical stance and gait is an important goal of rehabilitation. The purpose of this study was to investigate the effect of a novel discomfort-induced approach (that is based on using a single textured insole) on the alteration in the symmetry of gait and balance. Eleven healthy subjects (6 females and 5 males, mean age of 28.0 ± 4.1 years) were tested using the Computerized Dynamic Posturography and GaitRite systems when standing or walking while wearing standard footwear with the textured insole positioned either in the left or in the right shoe, and without the insole. Significant immediate effect of the textured insole was seen in the outcome measures of static (weight bearing) and dynamic (weight symmetry index, strength symmetry) balance tests (p < 0.05) as well as in gait symmetry (single support and swing phases) (p < 0.05). The results of the study indicate that a textured insole can significantly modify the symmetry of stance and gait in healthy individuals. Pilot data from individuals with stroke also showed a reduction in the asymmetry of gait when walking with the single textured insole in the shoe on the unaffected side. This outcome provides support for future studies on the efficacy of the textured insole in minimizing asymmetry of gait and posture in individuals in need.

  6. Dependence of gait parameters on height in typically developing children.

    PubMed

    Agostini, Valentina; Nascimbeni, Alberto; Di Nardo, Francesco; Fioretti, Sandro; Burattini, Laura; Knaflitz, Marco

    2015-08-01

    In clinical gait analysis is fundamental to have access to normative data, to be used as a reference in the interpretation of pathological walking. In a paediatric population this may be complicated by the dependence of gait parameters on child growth. The aim of this work is to provide the correlations of spatial-temporal gait parameters with children's height. We obtained the regression lines of cadence, double support, and gait phases, with respect to height, from a sample of 85 normally typically developing children aged 6 to 11. Our analysis of gait phases was not limited to the traditional analysis of stance and swing, but rather focused on the sub-phases of stance - heel contact, flat foot contact, push off - which proved to be an innovative approach to gait analysis. Heel contact decreased, flat foot contact increased and push off remained essentially unchanged with respect to children's height. These results may be useful in the interpretation of gait data in developing children, and the regression lines obtained may be used to normalize their gait parameters. PMID:26738051

  7. Automated detection of gait initiation and termination using wearable sensors.

    PubMed

    Novak, Domen; Reberšek, Peter; De Rossi, Stefano Marco Maria; Donati, Marco; Podobnik, Janez; Beravs, Tadej; Lenzi, Tommaso; Vitiello, Nicola; Carrozza, Maria Chiara; Munih, Marko

    2013-12-01

    This paper presents algorithms for detection of gait initiation and termination using wearable inertial measurement units and pressure-sensitive insoles. Body joint angles, joint angular velocities, ground reaction force and center of plantar pressure of each foot are obtained from these sensors and input into supervised machine learning algorithms. The proposed initiation detection method recognizes two events: gait onset (an anticipatory movement preceding foot lifting) and toe-off. The termination detection algorithm segments gait into steps, measures the signals over a buffer at the beginning of each step, and determines whether this measurement belongs to the final step. The approach is validated with 10 subjects at two gait speeds, using within-subject and subject-independent cross-validation. Results show that gait initiation can be detected timely and accurately, with few errors in the case of within-subject cross-validation and overall good performance in subject-independent cross-validation. Gait termination can be predicted in over 80% of trials well before the subject comes to a complete stop. Results also show that the two sensor types are equivalent in predicting gait initiation while inertial measurement units are generally superior in predicting gait termination. Potential use of the algorithms is foreseen primarily with assistive devices such as prostheses and exoskeletons.

  8. Gait abnormalities, ADHD, and environmental exposure to nitrous oxide.

    PubMed

    Fluegge, Keith

    2016-08-30

    Papadopoulos et al. (2014) investigated gait profiles of children with attention-deficit hyperactivity disorder-combined type (ADHD-CT) compared to typical developing (TD) controls. The authors reported differences in the gait profile of ADHD-CT in the self-selected fast speed category. Additionally, others have proposed a maturational delay hypothesis in gait, demonstrating that gait variability decreases with age in ADHD children. It has been previously suggested that the cognitive impairment seen in conditions like ADHD may result from chronic, environmental exposure to the air pollutant, nitrous oxide (N2O). Exposure to N2O is thought to exert its antinociceptive properties by stimulating release of dynorphin peptides in the central nervous system which act upon kappa opioid receptors (KOR). Opioid-mediated gait abnormalities in ADHD are supported with evidence that prodynorphin mutations in mice lead to cytotoxic levels of dynorphin A (DYN A) and contribute to abnormal gait profiles and gradual loss of motor coordination. Interestingly, constitutive activity of the KOR receptor in rat brain has been recently shown to undergo maturational alterations, suggesting that while altered gait profiles in ADHD may be a function of the enhanced opioidergic activity attributable to chronic exposure to the environmental air pollutant, N2O, age-attenuated constitutive activity of KOR in brain may explain the normalization of these altered gait profiles in older ADHD subjects. PMID:27285951

  9. Detection of the onset of gait initiation using kinematic sensors and EMG in transfemoral amputees.

    PubMed

    Wentink, E C; Schut, V G H; Prinsen, E C; Rietman, J S; Veltink, P H

    2014-01-01

    In this study we determined if detection of the onset of gait initiation in transfemoral amputees can be useful for voluntary control of upper leg prostheses. From six transfemoral amputees inertial sensor data and EMG were measured at the prosthetic leg during gait initiation. First, initial movement was detected from the inertial sensor data. Subsequently it was determined whether EMG could predict initial movement before detection based on the inertial sensors with comparable consistency as the inertial sensors. From the inertial sensors the initial movement can be determined. If the prosthetic leg leads, the upper leg accelerometer data was able to detect initial movement best. If the intact leg leads the upper leg gyroscope data performed best. Inertial sensors at the upper leg in general showed detections at the same time or earlier than those at the lower leg. EMG can predict initial movement up to a 138 ms in advance, when the prosthetic leg leads. One subject showed consistent EMG onset up to 248 ms before initial movement in the intact leg leading condition. A new method to detect initial movement from inertial sensors was presented and can be useful for additional prosthetic control. EMG measured at the prosthetic leg can be used for prediction of gait initiation when the prosthetic leg is leading, but for the intact leg leading condition this will not be of additional value.

  10. Are External Knee Load and EMG Measures Accurate Indicators of Internal Knee Contact Forces during Gait?

    PubMed Central

    Meyer, Andrew J.; D'Lima, Darryl D.; Besier, Thor F.; Lloyd, David G.; Colwell, Clifford W.; Fregly, Benjamin J.

    2013-01-01

    Mechanical loading is believed to be a critical factor in the development and treatment of knee osteoarthritis. However, the contact forces to which the knee articular surfaces are subjected during daily activities cannot be measured clinically. Thus, the ability to predict internal knee contact forces accurately using external measures (i.e., external knee loads and muscle EMG signals) would be clinically valuable. This study quantifies how well external knee load and EMG measures predict internal knee contact forces during gait. A single subject with a force-measuring tibial prosthesis and post-operative valgus alignment performed four gait patterns (normal, medial thrust, walking pole, and trunk sway) to induce a wide range of external and internal knee joint loads. Linear regression analyses were performed to assess how much of the variability in internal contact forces was accounted for by variability in the external measures. Though the different gait patterns successfully induced significant changes in the external and internal quantities, changes in external measures were generally weak indicators of changes in total, medial, and lateral contact force. Our results suggest that when total contact force may be changing, caution should be exercised when inferring changes in knee contact forces based on observed changes in external knee load and EMG measures. Advances in musculoskeletal modeling methods may be needed for accurate estimation of in vivo knee contact forces. PMID:23280647

  11. Microelectromechanical reciprocating-tooth indexing apparatus

    SciTech Connect

    Allen, James J.

    1999-01-01

    An indexing apparatus is disclosed that can be used to rotate a gear or move a rack in a precise, controllable manner. The indexing apparatus, based on a reciprocating shuttle driven by one or more actuators, can be formed either as a micromachine, or as a millimachine. The reciprocating shuttle of the indexing apparatus can be driven by a thermal, electrostatic or electromagnetic actuator, with one or more wedge-shaped drive teeth of the shuttle being moveable to engage and slide against indexing teeth on the gear or rack, thereby moving the gear or rack. The indexing apparatus can be formed by either surface micromachining processes or LIGA processes, depending on the size of the apparatus that is to be formed.

  12. Reciprocity in Adolescent and Caregiver Violence

    PubMed Central

    Bartle-Haring, Suzanne; Slesnick, Natasha; Carmona, Jasmin

    2014-01-01

    Over a 2-year period, with assessments every six months, the reciprocity in violent behaviors (verbal and physical) was investigated in a sample of 161 adolescents, who met the criteria for substance or alcohol abuse or dependence, and their caregivers, who participated in a clinical trial for family treatment for adolescent substance abuse. Using observed variables in a structural equation model with panel data, there was very little stability in violent behaviors across time from the perspectives of both the adolescents and caregivers. Evidence for violence reciprocity between adolescent and caregiver was demonstrated toward the end of the study period. The results are discussed in the context of previous literature about adolescent-to-parent violence. PMID:25684856

  13. Reciprocal allopreening in the Brownheaded Nuthatch

    USGS Publications Warehouse

    Barbour, D.B.; DeGange, A.R.

    1982-01-01

    In his extensive reviews of allopreening, Harrison (1965, 1969) did not record this behavior for the Sittidae, nor did Kilham (1968, 1972, 1973) mention observing this behavior in either White-breasted (Sitta carolinensis) or Red-breasted (S. canadensis) nuthatches. Norris (1958: 187), however, mentioned the occurrence of allopreening in Brown-headed Nuthatches (S. pusilia), in passing. Here we relate our observations of reciprocal allopreening between two Brown-headed Nuthatches.

  14. Feasibility analysis of reciprocating magnetic heat pumps

    NASA Technical Reports Server (NTRS)

    Larson, A. V.; Hartley, J. G.; Shelton, S. V.; Smith, M. M.

    1986-01-01

    The conceptual design selected for detailed system analysis and optimization is the reciprocating gadolinium core in a regenerative fluid column within the bore of a superconducting magnet. The thermodynamic properties of gadolinium are given. A computerized literature search for relevant papers was conducted and is being analyzed. Contact was made with suppliers of superconducting magnets and accessories, magnetic materials, and various types of hardware. A description of the model for the thermal analysis of the core and regenerator fluids is included.

  15. Variable-Aperture Reciprocating Reed Valve

    NASA Technical Reports Server (NTRS)

    Lindner, Jeffrey L. (Inventor); Myers, W. Neill (Inventor); Kelley, Anthony R. (Inventor); Yang, Hong Q. (Inventor)

    2015-01-01

    A variable-aperture reciprocating reed valve includes a valve body defining a through hole region having a contoured-profile portion. A semi-rigid plate is affixed on one side thereof to the valve body to define a cantilever extending across the through hole region. At least one free edge of the cantilever opposes the contoured-profile portion of the through hole region in a non-contact relationship.

  16. Summary measures for clinical gait analysis: a literature review.

    PubMed

    Cimolin, Veronica; Galli, Manuela

    2014-04-01

    Instrumented 3D-gait analysis (3D-GA) is an important method used to obtain information that is crucial for establishing the level of functional limitation due to pathology, observing its evolution over time and evaluating rehabilitative intervention effects. However, a typical 3D-GA evaluation produces a vast amount of data, and despite its objectivity, its use is complicated, and the data interpretation is difficult. It is even more difficult to obtain an overview on patient cohorts for a comparison. Moreover, there is a growing awareness of the need for a concise index, specifically, a single measure of the 'quality' of a particular gait pattern. Several gait summary measures, which have been used in conjunction with 3D-GA, have been proposed to objectify clinical impression, quantify the degree of gait deviation from normal, stratify the severity of pathology, document the changes in gait patterns over time and evaluate interventions.

  17. Upstream reciprocity and the evolution of gratitude

    PubMed Central

    Nowak, Martin A; Roch, Sébastien

    2006-01-01

    If someone is nice to you, you feel good and may be inclined to be nice to somebody else. This every day experience is borne out by experimental games: the recipients of an act of kindness are more likely to help in turn, even if the person who benefits from their generosity is somebody else. This behaviour, which has been called ‘upstream reciprocity’, appears to be a misdirected act of gratitude: you help somebody because somebody else has helped you. Does this make any sense from an evolutionary or a game theoretic perspective? In this paper, we show that upstream reciprocity alone does not lead to the evolution of cooperation, but it can evolve and increase the level of cooperation if it is linked to either direct or spatial reciprocity. We calculate the random walks of altruistic acts that are induced by upstream reciprocity. Our analysis shows that gratitude and other positive emotions, which increase the willingness to help others, can evolve in the competitive world of natural selection. PMID:17254983

  18. Nutating spider crank reciprocating piston machine

    SciTech Connect

    Shaffer, J.E.

    1991-07-02

    This patent describes reciprocating piston apparatus. It comprises a housing; a shaft journalled on the housing for rotation about a shaft axis; a plurality of cylinders each having a central longitudinal axis and disposed parallel to the shaft axis and located on the housing at positions angularly-spaced circumferentially about the shaft; a plurality of double-acting pistons having piston axes and centers, each the piston having a transverse bore therein and being respectively mounted for reciprocation within corresponding ones of the cylinders, each the bore having a longitudinal central axis normal to the respective cylinder axis; a mutating spider having a central hub portion mounted on the shaft obliquely of the shaft axis, and having a plurality of branches extending radially outward from the hub portion and terminating at terminal ends; and means directly connecting the terminal ends centrally to corresponding ones of the bores for transferring motion between reciprocation of the pistons and rotation of the shaft, and for restraining the spider from rotating with the shaft.

  19. Grooming reciprocity in male Tibetan macaques.

    PubMed

    Xia, Dong-Po; Li, Jin-Hua; Garber, Paul A; Matheson, Megan D; Sun, Bing-Hua; Zhu, Yong

    2013-10-01

    In several primate species, adult males are reported to compete for access to reproductive partners as well as forming affiliative and cohesive social bonds based on the exchange of goods or services. We hypothesized that among a broad set of fitness-maximizing strategies, grooming can be used by individual adult males to enhance social relationships through reciprocity and/or through the interchange of grooming for a different but equivalent good or service. We used focal animal sampling and continuously recorded dyadic grooming and agonistic interactions to test a series of predictions regarding male social interactions in a free-ranging group of Tibetan macaques (Macaca thibetana) at Huangshan, China. During the non-mating season or between males of similar rank throughout the year, grooming effort given was matched by grooming effort received. However, lower ranking males groomed higher ranking males at a greater rate and/or for a longer duration during both the mating and non-mating periods. We found that higher ranking males directed less aggression towards males with whom they formed a frequent grooming partnership, indicating that grooming received was interchanged for increased social tolerance. These data suggest that individual male Tibetan macaques employ alternative social strategies associated with grooming reciprocity or interchange depending on dominance rank and rates of aggression, and highlight the importance of both biological markets and grooming reciprocity as behavioral mechanisms used by resident adult males to form and maintain affiliative social bonds.

  20. Compression ratio control in reciprocating piston engines

    SciTech Connect

    Doundoulakis, G.J.

    1989-08-29

    The patent describes compression ratio control for reciprocating piston engines. It comprises: a reciprocating engine crankcase; a plurality of compression/expansion cylinders rigidly attached to the crankcase; each of the cylinders including a curved surface and a cylinder head; a fuel mixture in-taken in the cylinders; a piston reciprocating along each cylinder's curved surface for providing compression/expansion to the fuel mixture; a crank mechanism including a crankshaft rotating about an axial line that is substantially equidistant from the heads, crankcheek lobes radially extending from the crankshaft, crankpins inside and in contact with crankpin bearings, axially extending between the crankcheek lobes, and crankshaft journal bearings for providing low frictional support to the crankshaft; a connecting rod for each of the cylinders connecting the piston with the crankpin; crankshaft positioning; a first transmission gear, a crankshaft gear for meshing with the transmission gear, and a slot cut on the crankcase; wherein the constraint in the displacement of the crankshaft in the horizontal sense is provided by the vertical edges of the slot, and wherein the vertical edges of the slot are preferably being curved with a radius of curvature substantially equal to the average pitch diameter of the crankshaft gear and thee first transmission gear for accurate meshing of the gears.

  1. Reciprocity theory of many-body interactions

    NASA Astrophysics Data System (ADS)

    Agbormbai, Adolf A.

    1990-01-01

    The reciprocity approach is applied to the problem of many body interactions in which an arbitrary number of molecules simultaneously collide with one another at the same impact point in physical space. First, the relevant features in the theory of binary collisions are reviewed, and then the problem of three bodies is considered. It is shown that this reduces to the motion of two particles in the center of mass frame, in contrast to the binary problem which reduces to the motion of a single particle in this frame of reference. It is shown how the three body analysis may be generalized to incorporate an arbitrary number of bodies. In particular, the N body problem is shown to reduce to the motion of N-1 bodies in the center of mass system each of which scatters in the manner described above as well as interchange energy with the others. For the inelastic encounters in which internal energy excitations occur, the problem is decomposed into an internal transational energy exchange superposed on the elastic scattering. The internal-external exchange is formulated statistically via the principle of reciprocity at equilibrium. Techniques are illustrated only for three body collisions, the aim being to formulate a reciprocity equation from which the statistical models of the exchange may be constructed.

  2. Gait dynamics in Parkinson’s disease: Common and distinct behavior among stride length, gait variability, and fractal-like scaling

    PubMed Central

    Hausdorff, Jeffrey M.

    2009-01-01

    Parkinson’s disease (PD) is a common, debilitating neurodegenerative disease. Gait disturbances are a frequent cause of disability and impairment for patients with PD. This article provides a brief introduction to PD and describes the gait changes typically seen in patients with this disease. A major focus of this report is an update on the study of the fractal properties of gait in PD, the relationship between this feature of gait and stride length and gait variability, and the effects of different experimental conditions on these three gait properties. Implications of these findings are also briefly described. This update highlights the idea that while stride length, gait variability, and fractal scaling of gait are all impaired in PD, distinct mechanisms likely contribute to and are responsible for the regulation of these disparate gait properties. PMID:19566273

  3. Crowd-Sourced Amputee Gait Data: A Feasibility Study Using YouTube Videos of Unilateral Trans-Femoral Gait

    PubMed Central

    Gardiner, James; Gunarathne, Nuwan; Howard, David; Kenney, Laurence

    2016-01-01

    Collecting large datasets of amputee gait data is notoriously difficult. Additionally, collecting data on less prevalent amputations or on gait activities other than level walking and running on hard surfaces is rarely attempted. However, with the wealth of user-generated content on the Internet, the scope for collecting amputee gait data from alternative sources other than traditional gait labs is intriguing. Here we investigate the potential of YouTube videos to provide gait data on amputee walking. We use an example dataset of trans-femoral amputees level walking at self-selected speeds to collect temporal gait parameters and calculate gait asymmetry. We compare our YouTube data with typical literature values, and show that our methodology produces results that are highly comparable to data collected in a traditional manner. The similarity between the results of our novel methodology and literature values lends confidence to our technique. Nevertheless, clear challenges with the collection and interpretation of crowd-sourced gait data remain, including long term access to datasets, and a lack of validity and reliability studies in this area. PMID:27764226

  4. [The emergence of indirect reciprocity: evolutionary foundation of altruistic behavior based on "strict discriminator"].

    PubMed

    Mashima, Rie; Takahashi, Nobuyuki

    2005-12-01

    Although there have been a number of studies that theoretically and empirically examined altruism based on direct reciprocity, few have been conducted on how altruism based on indirect reciprocity emerges. Recent advances in biological research, however, have suggested possible answers to the question. For instance, Nowak and Sigmund (1998a, b) proposed that what they called image scoring strategy made indirect reciprocity possible. After critically examining their work, Leimar and Hammerstein (2001) pointed out several limitations to the theory, and instead proposed standing strategy as an explanation. Although careful attempts to replicate the findings by them and Panchanathan and Boyd (2003) supported the arguments against image scoring, we reveal that standing strategy was not a satisfactory answer either. Based on a series of evolutionary simulations, we propose a new strategy, which we call strict discriminator, as an alternative. Strict discriminators are discriminating altruists, similar to the altruists with image scoring or standing strategy, but they are different in that its criterion for discrimination is stricter: unconditional altruists are excluded from their reciprocity.

  5. Pilot demonstration of energy-efficient membrane bioreactor (MBR) using reciprocating submerged membrane.

    PubMed

    Ho, Jaeho; Smith, Shaleena; Patamasank, Jaren; Tontcheva, Petia; Kim, Gyu Dong; Roh, Hyung Keun

    2015-03-01

    Membrane bioreactor (MBR) is becoming popular for advanced wastewater treatment and water reuse. Air scouring to "shake" the membrane fibers is most suitable and applicable to maintain filtration without severe and rapidfouling. However, membrane fouling mitigating technologies are energy intensive. The goal of this research is to develop an alternative energy-saving MBR system to reduce energy consumption; a revolutionary system that will directly compete with air scouring technologies currently in the membrane water reuse market. The innovative MBR system, called reciprocation MBR (rMBR), prevents membrane fouling without the use of air scouring blowers. The mechanism featured is a mechanical reciprocating membrane frame that uses inertia to prevent fouling. Direct strong agitation of the fiber is also beneficial for the constant removal of solids built up on the membrane surface. The rMBR pilot consumes less energy than conventional coarse air scouring MBR systems. Specific energy consumption for membrane reciprocation for the pilot rMBR system was 0.072 kWh/m3 permeate produced at 40 LMH, which is 75% less than the conventional air scouring in an MBR system (0.29 kWh/m3). Reciprocation of the hollow-fiber membrane can overcome the hydrodynamic limitations of air scouring or cross-flow membrane systems with less energy consumption and/or higher energy efficiency. PMID:25842538

  6. Pilot demonstration of energy-efficient membrane bioreactor (MBR) using reciprocating submerged membrane.

    PubMed

    Ho, Jaeho; Smith, Shaleena; Patamasank, Jaren; Tontcheva, Petia; Kim, Gyu Dong; Roh, Hyung Keun

    2015-03-01

    Membrane bioreactor (MBR) is becoming popular for advanced wastewater treatment and water reuse. Air scouring to "shake" the membrane fibers is most suitable and applicable to maintain filtration without severe and rapidfouling. However, membrane fouling mitigating technologies are energy intensive. The goal of this research is to develop an alternative energy-saving MBR system to reduce energy consumption; a revolutionary system that will directly compete with air scouring technologies currently in the membrane water reuse market. The innovative MBR system, called reciprocation MBR (rMBR), prevents membrane fouling without the use of air scouring blowers. The mechanism featured is a mechanical reciprocating membrane frame that uses inertia to prevent fouling. Direct strong agitation of the fiber is also beneficial for the constant removal of solids built up on the membrane surface. The rMBR pilot consumes less energy than conventional coarse air scouring MBR systems. Specific energy consumption for membrane reciprocation for the pilot rMBR system was 0.072 kWh/m3 permeate produced at 40 LMH, which is 75% less than the conventional air scouring in an MBR system (0.29 kWh/m3). Reciprocation of the hollow-fiber membrane can overcome the hydrodynamic limitations of air scouring or cross-flow membrane systems with less energy consumption and/or higher energy efficiency.

  7. A patient-specific EMG-driven neuromuscular model for the potential use of human-inspired gait rehabilitation robots.

    PubMed

    Ma, Ye; Xie, Shengquan; Zhang, Yanxin

    2016-03-01

    A patient-specific electromyography (EMG)-driven neuromuscular model (PENm) is developed for the potential use of human-inspired gait rehabilitation robots. The PENm is modified based on the current EMG-driven models by decreasing the calculation time and ensuring good prediction accuracy. To ensure the calculation efficiency, the PENm is simplified into two EMG channels around one joint with minimal physiological parameters. In addition, a dynamic computation model is developed to achieve real-time calculation. To ensure the calculation accuracy, patient-specific muscle kinematics information, such as the musculotendon lengths and the muscle moment arms during the entire gait cycle, are employed based on the patient-specific musculoskeletal model. Moreover, an improved force-length-velocity relationship is implemented to generate accurate muscle forces. Gait analysis data including kinematics, ground reaction forces, and raw EMG signals from six adolescents at three different speeds were used to evaluate the PENm. The simulation results show that the PENm has the potential to predict accurate joint moment in real-time. The design of advanced human-robot interaction control strategies and human-inspired gait rehabilitation robots can benefit from the application of the human internal state provided by the PENm.

  8. Probabilistic Gait Classification in Children with Cerebral Palsy: A Bayesian Approach

    ERIC Educational Resources Information Center

    Van Gestel, Leen; De Laet, Tinne; Di Lello, Enrico; Bruyninckx, Herman; Molenaers, Guy; Van Campenhout, Anja; Aertbelien, Erwin; Schwartz, Mike; Wambacq, Hans; De Cock, Paul; Desloovere, Kaat

    2011-01-01

    Three-dimensional gait analysis (3DGA) generates a wealth of highly variable data. Gait classifications help to reduce, simplify and interpret this vast amount of 3DGA data and thereby assist and facilitate clinical decision making in the treatment of CP. CP gait is often a mix of several clinically accepted distinct gait patterns. Therefore,…

  9. Gait Patterns in Hemiplegic Children with Cerebral Palsy: Comparison of Right and Left Hemiplegia

    ERIC Educational Resources Information Center

    Galli, Manuela; Cimolin, Veronica; Rigoldi, Chiara; Tenore, Nunzio; Albertini, Giorgio

    2010-01-01

    The aims of this study are to compare quantitatively the gait strategy of the right and left hemiplegic children with Cerebral Palsy (CP) using gait analysis. The gait strategy of 28 right hemiparetic CP (RHG) and 23 left hemiparetic CP (LHG) was compared using gait analysis (spatio-temporal and kinematic parameters) and considering the hemiplegic…

  10. Gait Patterns in Twins with Cerebral Palsy: Similarities and Development over Time after Multilevel Surgery

    ERIC Educational Resources Information Center

    van Drongelen, Stefan; Dreher, Thomas; Heitzmann, Daniel W. W.; Wolf, Sebastian I.

    2013-01-01

    To examine gait patterns and gait quality, 7 twins with cerebral palsy were measured preoperatively and after surgical intervention. The aim was to study differences and/or similarities in gait between twins, the influence of personal characteristics and birth conditions, and to describe the development of gait over time after single event…

  11. Reciprocity or near-reciprocity of highly coupled enzymatic processes at the multidimensional inflection point.

    PubMed Central

    Caplan, S R

    1981-01-01

    It has recently been demonstrated that coupled enzymatic processes may possess, for a particular choice of the state variables, multidimensional inflection points in thermodynamic force-flow space. The conditions for reciprocity in the linear region near such a reference state, which may be far from equilibrium, are of considerable interest. It is shown by examining the associated Hill diagrams that all cycles in which a given pair of forces act contribute a corresponding pair of symmetrical terms to the Jacobian matrix characterizing perturbations about this stationary state. To the extent that these cycles dominate--i.e., to the extent that the system is highly coupled--reciprocity or near-reciprocity will be obeyed. This would be expected to be the case in most biological systems. PMID:6270670

  12. Reciprocity on the hardwood: passing patterns among professional basketball players.

    PubMed

    Willer, Robb; Sharkey, Amanda; Frey, Seth

    2012-01-01

    Past theory and research view reciprocal resource sharing as a fundamental building block of human societies. Most studies of reciprocity dynamics have focused on trading among individuals in laboratory settings. But if motivations to engage in these patterns of resource sharing are powerful, then we should observe forms of reciprocity even in highly structured group environments in which reciprocity does not clearly serve individual or group interests. To this end, we investigated whether patterns of reciprocity might emerge among teammates in professional basketball games. Using data from logs of National Basketball Association (NBA) games of the 2008-9 season, we estimated a series of conditional logistic regression models to test the impact of different factors on the probability that a given player would assist another player in scoring a basket. Our analysis found evidence for a direct reciprocity effect in which players who had "received" assists in the past tended to subsequently reciprocate their benefactors. Further, this tendency was time-dependent, with the probability of repayment highest soon after receiving an assist and declining as game time passed. We found no evidence for generalized reciprocity - a tendency to "pay forward" assists - and only very limited evidence for indirect reciprocity - a tendency to reward players who had sent others many assists. These findings highlight the power of reciprocity to shape human behavior, even in a setting characterized by extensive planning, division of labor, quick decision-making, and a focus on inter-group competition.

  13. Effects of robot-assisted gait training on the balance and gait of chronic stroke patients: focus on dependent ambulators.

    PubMed

    Cho, Duk Youn; Park, Si-Woon; Lee, Min Jin; Park, Dae Sung; Kim, Eun Joo

    2015-10-01

    [Purpose] The purpose of this study was to confirm the effect of robot-assisted gait training on the balance and gait ability of stroke patients who were dependent ambulators. [Subjects and Methods] Twenty stroke patients participated in this study. The participants were allocated to either group 1, which received robot-assisted gait training for 4 weeks followed by conventional physical therapy for 4 weeks, or group 2, which received the same treatments in the reverse order. Robot-assisted gait training was conducted for 30 min, 3 times a week for 4 weeks. The Berg Balance Scale, Modified Functional Reach Test, Functional Ambulation Category, Modified Ashworth Scale, Fugl-Meyer Assessment, Motricity Index, and Modified Barthel Index were assessed before and after treatment. To confirm the characteristics of patients who showed a significant increase in Berg Balance Scale after robot-assisted gait training as compared with physical therapy, subgroup analysis was conducted. [Results] Only lateral reaching and the Functional Ambulation Category were significantly increased following robot-assisted gait training. Subscale analyses identified 3 patient subgroups that responded well to robot-assisted gait training: a subgroup with hemiplegia, a subgroup in which the guidance force needed to be decreased to needed to be decreased to ≤45%, and a subgroup in which weight bearing was decreased to ≤21%. [Conclusion] The present study showed that robot-assisted gait training is not only effective in improving balance and gait performance but also improves trunk balance and motor skills required by high-severity stroke patients to perform activities daily living. Moreover, subscale analyses identified subgroups that responded well to robot-assisted gait training.

  14. Guiding task-oriented gait training after stroke or spinal cord injury by means of a biomechanical gait analysis.

    PubMed

    Nadeau, Sylvie; Duclos, Cyril; Bouyer, Laurent; Richards, Carol L

    2011-01-01

    To recover the ability to walk is one of the most important goals of persons recovering from a stroke or spinal cord injury (SCI). While a task-oriented approach to gait training is recommended, randomized controlled trials or meta-analyses comparing different methods of delivering training have failed in general to demonstrate the superiority of one approach over the other. The large variations in the mean outcome gait measures reported in these studies reflect, at least in part, the heterogeneity of the sensorimotor impairments underlying the gait disability as well as variations in the therapeutic response. The purpose of this chapter is to demonstrate that biomechanical gait analysis can reveal information pertinent to the selection of a task-oriented approach to enhance gait training as well as the therapeutic response that clinical evaluations alone cannot provide. We first briefly review locomotor impairments underlying the gait disability after stroke and SCI as well as the effects of selected technological task-oriented gait training interventions. We then give examples that demonstrate the use of gait analysis to pinpoint underlying impairments that can guide the choice of sensorimotor therapy and then immediately identify responders to the intervention. Such an individualized approach should promote therapeutic efficacy while leading over time to the identification of clinical indices to guide therapy when gait analysis is not feasible. Given the requirements of a gait analysis laboratory and the qualified personnel to capture and interpret the data, future studies will need to demonstrate the feasibility of the technological proposed approach and assess the costs and benefits for the health care system.

  15. Effects of robot-assisted gait training on the balance and gait of chronic stroke patients: focus on dependent ambulators

    PubMed Central

    Cho, Duk Youn; Park, Si-Woon; Lee, Min Jin; Park, Dae Sung; Kim, Eun Joo

    2015-01-01

    [Purpose] The purpose of this study was to confirm the effect of robot-assisted gait training on the balance and gait ability of stroke patients who were dependent ambulators. [Subjects and Methods] Twenty stroke patients participated in this study. The participants were allocated to either group 1, which received robot-assisted gait training for 4 weeks followed by conventional physical therapy for 4 weeks, or group 2, which received the same treatments in the reverse order. Robot-assisted gait training was conducted for 30 min, 3 times a week for 4 weeks. The Berg Balance Scale, Modified Functional Reach Test, Functional Ambulation Category, Modified Ashworth Scale, Fugl-Meyer Assessment, Motricity Index, and Modified Barthel Index were assessed before and after treatment. To confirm the characteristics of patients who showed a significant increase in Berg Balance Scale after robot-assisted gait training as compared with physical therapy, subgroup analysis was conducted. [Results] Only lateral reaching and the Functional Ambulation Category were significantly increased following robot-assisted gait training. Subscale analyses identified 3 patient subgroups that responded well to robot-assisted gait training: a subgroup with hemiplegia, a subgroup in which the guidance force needed to be decreased to needed to be decreased to ≤45%, and a subgroup in which weight bearing was decreased to ≤21%. [Conclusion] The present study showed that robot-assisted gait training is not only effective in improving balance and gait performance but also improves trunk balance and motor skills required by high-severity stroke patients to perform activities daily living. Moreover, subscale analyses identified subgroups that responded well to robot-assisted gait training. PMID:26644642

  16. A collisional perspective on quadrupedal gait dynamics

    PubMed Central

    Lee, David V.; Bertram, John E. A.; Anttonen, Jennifer T.; Ros, Ivo G.; Harris, Sarah L.; Biewener, Andrew A.

    2011-01-01

    The analysis of terrestrial locomotion over the past half century has focused largely on strategies of mechanical energy recovery used during walking and running. In contrast, we describe the underlying mechanics of legged locomotion as a collision-like interaction that redirects the centre of mass (CoM). We introduce the collision angle, determined by the angle between the CoM force and velocity vectors, and show by computing the collision fraction, a ratio of actual to potential collision, that the quadrupedal walk and gallop employ collision-reduction strategies while the trot permits greater collisions. We provide the first experimental evidence that a collision-based approach can differentiate quadrupedal gaits and quantify interspecific differences. Furthermore, we show that this approach explains the physical basis of a commonly used locomotion metric, the mechanical cost of transport. Collision angle and collision fraction provide a unifying analysis of legged locomotion which can be applied broadly across animal size, leg number and gait. PMID:21471189

  17. A synergetic model for human gait transitions

    NASA Astrophysics Data System (ADS)

    Abdolvahab, Mohammad

    2015-09-01

    Gait transitions have been considered as bifurcations between states (e.g. walking or running modes) of a nonlinear dynamical system. A top-down synergetic approach to model gait transitions has been adapted from Frank et al. (2009) and applied to two sets of empirical observations. In this approach, it is assumed that the amplitudes of the spatio-temporal modes of locomotion satisfy a generic form of evolution equations that are known to hold for animate and inanimate self-organizing systems. The presented experimental results focus on hysteresis in human walk-to-run and run-to-walk transitions on a treadmill as a function of treadmill inclination and acceleration, the rate at which speed was increased or decreased during experimental trials. The bi-stability in the synergetic model is assumed to account for the hysteretic transitions. Accordingly, the relevant parameters of the model were estimated from the empirical data and the model's efficacy in predicting the observed hysteresis effects was evaluated.

  18. Gait generation and control in a climbing hexapod robot

    NASA Astrophysics Data System (ADS)

    Rizzi, A. A.; Haynes, G. C.; Full, R. J.; Koditschek, D. E.

    2006-05-01

    We discuss the gait generation and control architecture of a bioinspired climbing robot that presently climbs a variety of vertical surfaces, including carpet, cork and a growing range of stucco-like surfaces in the quasi-static regime. The initial version of the robot utilizes a collection of gaits (cyclic feed-forward motion patterns) to locomote over these surfaces, with each gait tuned for a specific surface and set of operating conditions. The need for more flexibility in gait specification (e.g., adjusting number of feet on the ground), more intricate shaping of workspace motions (e.g., shaping the details of the foot attachment and detachment trajectories), and the need to encode gait "transitions" (e.g., tripod to pentapod gait structure) has led us to separate this trajectory generation scheme into the functional composition of a phase assigning transformation of the "clock space" (the six dimensional torus) followed by a map from phase into leg joints that decouples the geometric details of a particular gait. This decomposition also supports the introduction of sensory feedback to allow recovery from unexpected event and to adapt to changing surface geometries.

  19. Symmetry in locomotor central pattern generators and animal gaits

    NASA Astrophysics Data System (ADS)

    Golubitsky, Martin; Stewart, Ian; Buono, Pietro-Luciano; Collins, J. J.

    1999-10-01

    Animal locomotion is controlled, in part, by a central pattern generator (CPG), which is an intraspinal network of neurons capable of generating a rhythmic output. The spatio-temporal symmetries of the quadrupedal gaits walk, trot and pace lead to plausible assumptions about the symmetries of locomotor CPGs. These assumptions imply that the CPG of a quadruped should consist of eight nominally identical subcircuits, arranged in an essentially unique matter. Here we apply analogous arguments to myriapod CPGs. Analyses based on symmetry applied to these networks lead to testable predictions, including a distinction between primary and secondary gaits, the existence of a new primary gait called `jump', and the occurrence of half-integer wave numbers in myriapod gaits. For bipeds, our analysis also predicts two gaits with the out-of-phase symmetry of the walk and two gaits with the in-phase symmetry of the hop. We present data that support each of these predictions. This work suggests that symmetry can be used to infer a plausible class of CPG network architectures from observed patterns of animal gaits.

  20. Gait biometrics under spoofing attacks: an experimental investigation

    NASA Astrophysics Data System (ADS)

    Hadid, Abdenour; Ghahramani, Mohammad; Kellokumpu, Vili; Feng, Xiaoyi; Bustard, John; Nixon, Mark

    2015-11-01

    Gait is a relatively biometric modality which has a precious advantage over other modalities, such as iris and voice, in that it can be easily captured from a distance. Although it has recently become a topic of great interest in biometric research, there has been little investigation into gait spoofing attacks where a person tries to imitate the clothing or walking style of someone else. We recently analyzed for the first time the effects of spoofing attacks on silhouette-based gait biometric systems and showed that it was indeed possible to spoof gait biometric systems by clothing impersonation and the deliberate selection of a target that has a similar build to the attacker. To gain deeper insight into the performance of current gait biometric systems under spoofing attacks, we provide a thorough investigation on how clothing can be used to spoof a target and evaluate the performance of two state-of-the-art recognition methods on a gait spoofing database recorded at the University of Southampton. Furthermore, we describe and evaluate an initial solution coping with gait spoofing attacks. The obtained results are very promising and point out interesting findings which can be used for future investigations.

  1. Turtle mimetic soft robot with two swimming gaits.

    PubMed

    Song, Sung-Hyuk; Kim, Min-Soo; Rodrigue, Hugo; Lee, Jang-Yeob; Shim, Jae-Eul; Kim, Min-Cheol; Chu, Won-Shik; Ahn, Sung-Hoon

    2016-06-01

    This paper presents a biomimetic turtle flipper actuator consisting of a shape memory alloy composite structure for implementation in a turtle-inspired autonomous underwater vehicle. Based on the analysis of the Chelonia mydas, the flipper actuator was divided into three segments containing a scaffold structure fabricated using a 3D printer. According to the filament stacking sequence of the scaffold structure in the actuator, different actuating motions can be realized and three different types of scaffold structures were proposed to replicate the motion of the different segments of the flipper of the Chelonia mydas. This flipper actuator can mimic the continuous deformation of the forelimb of Chelonia mydas which could not be realized in previous motor based robot. This actuator can also produce two distinct motions that correspond to the two different swimming gaits of the Chelonia mydas, which are the routine and vigorous swimming gaits, by changing the applied current sequence of the SMA wires embedded in the flipper actuator. The generated thrust and the swimming efficiency in each swimming gait of the flipper actuator were measured and the results show that the vigorous gait has a higher thrust but a relatively lower swimming efficiency than the routine gait. The flipper actuator was implemented in a biomimetic turtle robot, and its average swimming speed in the routine and vigorous gaits were measured with the vigorous gait being capable of reaching a maximum speed of 11.5 mm s(-1). PMID:27145061

  2. Turtle mimetic soft robot with two swimming gaits.

    PubMed

    Song, Sung-Hyuk; Kim, Min-Soo; Rodrigue, Hugo; Lee, Jang-Yeob; Shim, Jae-Eul; Kim, Min-Cheol; Chu, Won-Shik; Ahn, Sung-Hoon

    2016-05-04

    This paper presents a biomimetic turtle flipper actuator consisting of a shape memory alloy composite structure for implementation in a turtle-inspired autonomous underwater vehicle. Based on the analysis of the Chelonia mydas, the flipper actuator was divided into three segments containing a scaffold structure fabricated using a 3D printer. According to the filament stacking sequence of the scaffold structure in the actuator, different actuating motions can be realized and three different types of scaffold structures were proposed to replicate the motion of the different segments of the flipper of the Chelonia mydas. This flipper actuator can mimic the continuous deformation of the forelimb of Chelonia mydas which could not be realized in previous motor based robot. This actuator can also produce two distinct motions that correspond to the two different swimming gaits of the Chelonia mydas, which are the routine and vigorous swimming gaits, by changing the applied current sequence of the SMA wires embedded in the flipper actuator. The generated thrust and the swimming efficiency in each swimming gait of the flipper actuator were measured and the results show that the vigorous gait has a higher thrust but a relatively lower swimming efficiency than the routine gait. The flipper actuator was implemented in a biomimetic turtle robot, and its average swimming speed in the routine and vigorous gaits were measured with the vigorous gait being capable of reaching a maximum speed of 11.5 mm s(-1).

  3. Revisiting "The evolution of reciprocity in sizable groups": continuous reciprocity in the repeated n-person prisoner's dilemma.

    PubMed

    Takezawa, Masanori; Price, Michael E

    2010-05-21

    For many years in evolutionary science, the consensus view has been that while reciprocal altruism can evolve in dyadic interactions, it is unlikely to evolve in sizable groups. This view had been based on studies which have assumed cooperation to be discrete rather than continuous (i.e., individuals can either fully cooperate or else fully defect, but they cannot continuously vary their level of cooperation). In real world cooperation, however, cooperation is often continuous. In this paper, we re-examine the evolution of reciprocity in sizable groups by presenting a model of the n-person prisoner's dilemma that assumes continuous rather than discrete cooperation. This model shows that continuous reciprocity has a dramatically wider basin of attraction than discrete reciprocity, and that this basin's size increases with efficiency of cooperation (marginal per capita return). Further, we find that assortative interaction interacts synergistically with continuous reciprocity to a much greater extent than it does with discrete reciprocity. These results suggest that previous models may have underestimated reciprocity's adaptiveness in groups. However, we also find that the invasion of continuous reciprocators into a population of unconditional defectors becomes realistic only within a narrow parameter space in which the efficiency of cooperation is close to its maximum bound. Therefore our model suggests that continuous reciprocity can evolve in large groups more easily than discrete reciprocity only under unusual circumstances.

  4. Gait variability and basal ganglia disorders: stride-to-stride variations of gait cycle timing in Parkinson's disease and Huntington's disease

    NASA Technical Reports Server (NTRS)

    Hausdorff, J. M.; Cudkowicz, M. E.; Firtion, R.; Wei, J. Y.; Goldberger, A. L.

    1998-01-01

    The basal ganglia are thought to play an important role in regulating motor programs involved in gait and in the fluidity and sequencing of movement. We postulated that the ability to maintain a steady gait, with low stride-to-stride variability of gait cycle timing and its subphases, would be diminished with both Parkinson's disease (PD) and Huntington's disease (HD). To test this hypothesis, we obtained quantitative measures of stride-to-stride variability of gait cycle timing in subjects with PD (n = 15), HD (n = 20), and disease-free controls (n = 16). All measures of gait variability were significantly increased in PD and HD. In subjects with PD and HD, gait variability measures were two and three times that observed in control subjects, respectively. The degree of gait variability correlated with disease severity. In contrast, gait speed was significantly lower in PD, but not in HD, and average gait cycle duration and the time spent in many subphases of the gait cycle were similar in control subjects, HD subjects, and PD subjects. These findings are consistent with a differential control of gait variability, speed, and average gait cycle timing that may have implications for understanding the role of the basal ganglia in locomotor control and for quantitatively assessing gait in clinical settings.

  5. The integrative role of the pedunculopontine nucleus in human gait.

    PubMed

    Lau, Brian; Welter, Marie-Laure; Belaid, Hayat; Fernandez Vidal, Sara; Bardinet, Eric; Grabli, David; Karachi, Carine

    2015-05-01

    The brainstem pedunculopontine nucleus has a likely, although unclear, role in gait control, and is a potential deep brain stimulation target for treating resistant gait disorders. These disorders are a major therapeutic challenge for the ageing population, especially in Parkinson's disease where gait and balance disorders can become resistant to both dopaminergic medication and subthalamic nucleus stimulation. Here, we present electrophysiological evidence that the pedunculopontine and subthalamic nuclei are involved in distinct aspects of gait using a locomotor imagery task in 14 patients with Parkinson's disease undergoing surgery for the implantation of pedunculopontine or subthalamic nuclei deep brain stimulation electrodes. We performed electrophysiological recordings in two phases, once during surgery, and again several days after surgery in a subset of patients. The majority of pedunculopontine nucleus neurons (57%) recorded intrasurgically exhibited changes in activity related to different task components, with 29% modulated during visual stimulation, 41% modulated during voluntary hand movement, and 49% modulated during imaginary gait. Pedunculopontine nucleus local field potentials recorded post-surgically were modulated in the beta and gamma bands during visual and motor events, and we observed alpha and beta band synchronization that was sustained for the duration of imaginary gait and spatially localized within the pedunculopontine nucleus. In contrast, significantly fewer subthalamic nucleus neurons (27%) recorded intrasurgically were modulated during the locomotor imagery, with most increasing or decreasing activity phasically during the hand movement that initiated or terminated imaginary gait. Our data support the hypothesis that the pedunculopontine nucleus influences gait control in manners extending beyond simply driving pattern generation. In contrast, the subthalamic nucleus seems to control movement execution that is not likely to be gait

  6. Observational gait assessment tools in paediatrics--a systematic review.

    PubMed

    Rathinam, Chandrasekar; Bateman, Andrew; Peirson, Janet; Skinner, Jane

    2014-06-01

    Instrumented gait analysis (IGA) is an expensive technique used to objectively detect gait abnormalities in children. Observational gait assessment is considered as a cost effective alternate for IGA in regular clinical practice. This article is aimed at systematically reviewing the available paediatric gait analysis tools and examines their reliability and validity compared to IGA. This review also examines the structure of these tools, their clinical use and limitations. Articles were searched from PubMed, CINHL, AMED, BNI, EMBASE, PEDro and Cochrane library from the earliest record on the database to December 2012. Hand searches were carried out in a few journals. Studies that examined children's gait using a structured assessment tool were included and analysed for their quality, reliability and validity. Pre-established criteria were used to judge the quality of methodology and reliability and validity. Five observational gait tools for children with Cerebral Palsy (CP) and one for children with Downs Syndrome were identified. Nine studies related to children with CP were enrolled for this review. None of the tools have accomplished the level of IGA's consistency. Edinburgh Visual Gait Score (EVGS) was found to have better reliability and validity than the other tools. Very limited studies were available for most of the gait assessment tools therefore their clinical use cannot be judged based on the existing evidence. EVGS was found to have better concurrent validity and reliability and it should be considered to assess CP gait in regular practice. Future work to investigate the use of low cost technology to improve observers' accuracy of EVGS is suggested.

  7. Observational gait assessment tools in paediatrics--a systematic review.

    PubMed

    Rathinam, Chandrasekar; Bateman, Andrew; Peirson, Janet; Skinner, Jane

    2014-06-01

    Instrumented gait analysis (IGA) is an expensive technique used to objectively detect gait abnormalities in children. Observational gait assessment is considered as a cost effective alternate for IGA in regular clinical practice. This article is aimed at systematically reviewing the available paediatric gait analysis tools and examines their reliability and validity compared to IGA. This review also examines the structure of these tools, their clinical use and limitations. Articles were searched from PubMed, CINHL, AMED, BNI, EMBASE, PEDro and Cochrane library from the earliest record on the database to December 2012. Hand searches were carried out in a few journals. Studies that examined children's gait using a structured assessment tool were included and analysed for their quality, reliability and validity. Pre-established criteria were used to judge the quality of methodology and reliability and validity. Five observational gait tools for children with Cerebral Palsy (CP) and one for children with Downs Syndrome were identified. Nine studies related to children with CP were enrolled for this review. None of the tools have accomplished the level of IGA's consistency. Edinburgh Visual Gait Score (EVGS) was found to have better reliability and validity than the other tools. Very limited studies were available for most of the gait assessment tools therefore their clinical use cannot be judged based on the existing evidence. EVGS was found to have better concurrent validity and reliability and it should be considered to assess CP gait in regular practice. Future work to investigate the use of low cost technology to improve observers' accuracy of EVGS is suggested. PMID:24798609

  8. Reputation for reciprocity engages the brain reward center

    PubMed Central

    Phan, K. Luan; Sripada, Chandra Sekhar; Angstadt, Mike; McCabe, Kevin

    2010-01-01

    Brain reward circuitry, including ventral striatum and orbitofrontal cortex, has been independently implicated in preferences for fair and cooperative outcomes as well as learning of reputations. Using functional MRI (fMRI) and a “trust game” task involving iterative exchanges with fictive partners who acquire different reputations for reciprocity, we measured brain responses in 36 healthy adults when positive actions (entrust investment to partners) yield positive returns (reciprocity) and how these brain responses are modulated by partner reputation for repayment. Here we show that positive reciprocity robustly engages the ventral striatum and orbitofrontal cortex. Moreover, this signal of reciprocity in the ventral striatum appears selectively in response to partners who have consistently returned the investment (e.g., a reputation for reciprocity) and is absent for partners who lack a reputation for reciprocity. These findings elucidate a fundamental brain mechanism, via reward-related neural substrates, by which human cooperative relationships are initiated and sustained. PMID:20615982

  9. Mortality salience increases personal relevance of the norm of reciprocity.

    PubMed

    Schindler, Simon; Reinhard, Marc-André; Stahlberg, Dagmar

    2012-10-01

    Research on terror management theory found evidence that people under mortality salience strive to live up to salient cultural norms and values, like egalitarianism, pacifism, or helpfulness. A basic, strongly internalized norm in most human societies is the norm of reciprocity: people should support those who supported them (i.e., positive reciprocity), and people should injure those who injured them (i.e., negative reciprocity), respectively. In an experiment (N = 98; 47 women, 51 men), mortality salience overall significantly increased personal relevance of the norm of reciprocity (M = 4.45, SD = 0.65) compared to a control condition (M = 4.19, SD = 0.59). Specifically, under mortality salience there was higher motivation to punish those who treated them unfavourably (negative norm of reciprocity). Unexpectedly, relevance of the norm of positive reciprocity remained unaffected by mortality salience. Implications and limitations are discussed.

  10. Gait and menstrual cycle: ovulating women use sexier gaits and walk slowly ahead of men.

    PubMed

    Guéguen, Nicolas

    2012-04-01

    Previous research has demonstrated that women's physical appearance or sexual interest is different across the menstrual cycle. However, the nonverbal behavior of women toward men according to their menstrual cycle has not been previously explored. In this study, the gait of women walking ahead a male confederate was recorded with the help of a spy-camera. The amount of time that women spent walking was the first dependent variable whereas the extent to which the women were perceived to be sexually attractive by two judges was the second dependent variable. Comparisons were performed according to the women's ovulation phase measured with an LH salivary test. Near ovulation, it was found that women walked slower and their gait was subjectively rated as sexier. Such behaviors were interpreted as unconscious desires of women near ovulation to reinforce their attractiveness in order to attract more men and to increase their choice of a partner. PMID:22245227

  11. Gait and menstrual cycle: ovulating women use sexier gaits and walk slowly ahead of men.

    PubMed

    Guéguen, Nicolas

    2012-04-01

    Previous research has demonstrated that women's physical appearance or sexual interest is different across the menstrual cycle. However, the nonverbal behavior of women toward men according to their menstrual cycle has not been previously explored. In this study, the gait of women walking ahead a male confederate was recorded with the help of a spy-camera. The amount of time that women spent walking was the first dependent variable whereas the extent to which the women were perceived to be sexually attractive by two judges was the second dependent variable. Comparisons were performed according to the women's ovulation phase measured with an LH salivary test. Near ovulation, it was found that women walked slower and their gait was subjectively rated as sexier. Such behaviors were interpreted as unconscious desires of women near ovulation to reinforce their attractiveness in order to attract more men and to increase their choice of a partner.

  12. Reciprocity theory of gas surface interactions

    NASA Astrophysics Data System (ADS)

    Agbormbai, Adolf A.

    1989-11-01

    Since the Direct Simulation Monte Carlo (DSMC) method has established itself as a standard technique for numerically computing rarefied gas flows, it follows that to develop the theory of rarefied gas dynamics a framework for its fundamental microscopic processes needs to be formulated, i.e., intermolecular collisions and gas surface interactions, which lead to rigorous statistical models that can be utilized in the code. In this report attention is focussed on the mechanism of gas surface interactions. A reciprocity theory for it, which leads to models that can be utilized in the DSMC code, is formulated.

  13. [Application and evaluation of the VICON system in gait analysis].

    PubMed

    Lin, J H; Chou, Y L; Ju, M S; Sung, Y T

    1990-01-01

    By employing the VICON system, segment angular displacement, velocity and acceleration of the lower limbs were achieved from an Above-Knee (A/K) Amputee using a constant friction prosthesis during the swing phase of the gait cycle. By applying computer for data analysis and inputing anthropometric data of the (A/K) Amputee, kinematic trajectory and a stick diagram of lower limbs were obtained. The data were then compared with those obtained from normal subjects. The results showed that the VICON system can provide quantitative analysis of several important parameters in the gait cycle and that it is very helpful in the evaluation and rehabilitation training of abnormal gait.

  14. Neural correlate of human reciprocity in social interactions.

    PubMed

    Sakaiya, Shiro; Shiraito, Yuki; Kato, Junko; Ide, Hiroko; Okada, Kensuke; Takano, Kouji; Kansaku, Kenji

    2013-01-01

    Reciprocity plays a key role maintaining cooperation in society. However, little is known about the neural process that underpins human reciprocity during social interactions. Our neuroimaging study manipulated partner identity (computer, human) and strategy (random, tit-for-tat) in repeated prisoner's dilemma games and investigated the neural correlate of reciprocal interaction with humans. Reciprocal cooperation with humans but exploitation of computers by defection was associated with activation in the left amygdala. Amygdala activation was also positively and negatively correlated with a preference change for human partners following tit-for-tat and random strategies, respectively. The correlated activation represented the intensity of positive feeling toward reciprocal and negative feeling toward non-reciprocal partners, and so reflected reciprocity in social interaction. Reciprocity in social interaction, however, might plausibly be misinterpreted and so we also examined the neural coding of insight into the reciprocity of partners. Those with and without insight revealed differential brain activation across the reward-related circuitry (i.e., the right middle dorsolateral prefrontal cortex and dorsal caudate) and theory of mind (ToM) regions [i.e., ventromedial prefrontal cortex (VMPFC) and precuneus]. Among differential activations, activation in the precuneus, which accompanied deactivation of the VMPFC, was specific to those without insight into human partners who were engaged in a tit-for-tat strategy. This asymmetric (de)activation might involve specific contributions of ToM regions to the human search for reciprocity. Consequently, the intensity of emotion attached to human reciprocity was represented in the amygdala, whereas insight into the reciprocity of others was reflected in activation across the reward-related and ToM regions. This suggests the critical role of mentalizing, which was not equated with reward expectation during social interactions.

  15. Neural correlate of human reciprocity in social interactions

    PubMed Central

    Sakaiya, Shiro; Shiraito, Yuki; Kato, Junko; Ide, Hiroko; Okada, Kensuke; Takano, Kouji; Kansaku, Kenji

    2013-01-01

    Reciprocity plays a key role maintaining cooperation in society. However, little is known about the neural process that underpins human reciprocity during social interactions. Our neuroimaging study manipulated partner identity (computer, human) and strategy (random, tit-for-tat) in repeated prisoner's dilemma games and investigated the neural correlate of reciprocal interaction with humans. Reciprocal cooperation with humans but exploitation of computers by defection was associated with activation in the left amygdala. Amygdala activation was also positively and negatively correlated with a preference change for human partners following tit-for-tat and random strategies, respectively. The correlated activation represented the intensity of positive feeling toward reciprocal and negative feeling toward non-reciprocal partners, and so reflected reciprocity in social interaction. Reciprocity in social interaction, however, might plausibly be misinterpreted and so we also examined the neural coding of insight into the reciprocity of partners. Those with and without insight revealed differential brain activation across the reward-related circuitry (i.e., the right middle dorsolateral prefrontal cortex and dorsal caudate) and theory of mind (ToM) regions [i.e., ventromedial prefrontal cortex (VMPFC) and precuneus]. Among differential activations, activation in the precuneus, which accompanied deactivation of the VMPFC, was specific to those without insight into human partners who were engaged in a tit-for-tat strategy. This asymmetric (de)activation might involve specific contributions of ToM regions to the human search for reciprocity. Consequently, the intensity of emotion attached to human reciprocity was represented in the amygdala, whereas insight into the reciprocity of others was reflected in activation across the reward-related and ToM regions. This suggests the critical role of mentalizing, which was not equated with reward expectation during social interactions

  16. Predictors of Gait Speeds and the Relationship of Gait Speeds to Falls in Men and Women with Parkinson Disease

    PubMed Central

    Nemanich, Samuel T.; Duncan, Ryan P.; Dibble, Leland E.; Cavanaugh, James T.; Ellis, Terry D.; Ford, Matthew P.; Foreman, Kenneth B.; Earhart, Gammon M.

    2013-01-01

    Gait difficulties and falls are commonly reported in people with Parkinson disease (PD). Reduction in gait speed is a major characteristic of Parkinsonian gait, yet little is known about its underlying determinants, its ability to reflect an internal reservation about walking, or its relationship to falls. To study these issues, we selected age, disease severity, and nonmotor factors (i.e., depression, quality of life, balance confidence, and exercise beliefs and attitudes) to predict self-selected (SELF), fast-as-possible (FAST), and the difference (DIFF) between these walking speeds in 78 individuals with PD. We also examined gender differences in gait speeds and evaluated how gait speeds were related to a retrospective fall report. Age, disease severity, and balance confidence were strong predictors of SELF, FAST, and, to a lesser extent, DIFF. All three parameters were strongly associated with falling. DIFF was significantly greater in men compared to women and was significantly associated with male but not female fallers. The results supported the clinical utility of using a suite of gait speed parameters to provide insight into the gait difficulties and differentiating between fallers in people with PD. PMID:23841020

  17. A robust real-time gait event detection using wireless gyroscope and its application on normal and altered gaits.

    PubMed

    Gouwanda, Darwin; Gopalai, Alpha Agape

    2015-02-01

    Gait events detection allows clinicians and biomechanics researchers to determine timing of gait events, to estimate duration of stance phase and swing phase and to segment gait data. It also aids biomedical engineers to improve the design of orthoses and FES (functional electrical stimulation) systems. In recent years, researchers have resorted to using gyroscopes to determine heel-strike (HS) and toe-off (TO) events in gait cycles. However, these methods are subjected to significant delays when implemented in real-time gait monitoring devices, orthoses, and FES systems. Therefore, the work presented in this paper proposes a method that addresses these delays, to ensure real-time gait event detection. The proposed algorithm combines the use of heuristics and zero-crossing method to identify HS and TO. Experiments involving: (1) normal walking; (2) walking with knee brace; and (3) walking with ankle brace for overground walking and treadmill walking were designed to verify and validate the identified HS and TO. The performance of the proposed method was compared against the established gait detection algorithms. It was observed that the proposed method produced detection rate that was comparable to earlier reported methods and recorded reduced time delays, at an average of 100 ms.

  18. The effect of gait training with shoe inserts on the improvement of pain and gait in sacroiliac joint patients

    PubMed Central

    Cho, Byung-Yun; Yoon, Jung-Gyu

    2015-01-01

    [Purpose] The purpose of the current research was to identify how gait training with shoe inserts affects the pain and gait of sacroiliac joint dysfunction patients. [Subjects and Methods] Thirty subjects were randomly selected and assigned to be either the experimental group (gait training with shoe insert group) or control group. Each group consisted of 15 patients. Pain was measured by Visual Analogue Scale, and foot pressure in a standing position and during gait was measured with a Gateview AFA-50 system (Alpus, Seoul, Republic of Korea). A paired sample t-test was used to compare the pain and gait of the sacroiliac joint before and after the intervention. Correlation between pain and walking after gait training with shoe inserts was examined by Pearson test. The level of significance was set at α=0.05. [Results] It was found that application of the intervention to the experimental group resulted in a significant decrease in sacroiliac joint pain. It was also found that there was a significant correlation between Visual Analogue Scale score and dynamic asymmetric index (r= 0.796) and that there was a negative correlation between Visual Analogue Scale score and forefoot/rear foot peak pressure ratio (r=-0.728). [Conclusion] The results of our analysis lead us to conclude that the intervention with shoe inserts had a significant influence on the pain and gait of sacroiliac joint patients. PMID:26357428

  19. The effect of Tai Chi exercise on gait initiation and gait performance in persons with Parkinson's disease.

    PubMed

    Amano, Shinichi; Nocera, Joe R; Vallabhajosula, Srikant; Juncos, Jorge L; Gregor, Robert J; Waddell, Dwight E; Wolf, Steven L; Hass, Chris J

    2013-11-01

    Gait dysfunction and postural instability are two debilitating symptoms in persons with Parkinson's disease (PD). Tai Chi exercise has recently gained attention as an attractive intervention for persons with PD because of its known potential to reduce falls and improve postural control, walking abilities, and safety at a low cost. The purpose of this report is to investigate the effect of Tai Chi exercise on dynamic postural control during gait initiation and gait performance in persons with idiopathic PD, and to determine whether these benefits could be replicated in two different environments, as complementary projects. In these two separate projects, a total of 45 participants with PD were randomly assigned to either a Tai Chi group or a control group. The Tai Chi groups in both projects completed a 16-week Tai Chi exercise session, while the control groups consisted of either a placebo (i.e., Qi-Gong) or non-exercise group. Tai Chi did not significantly improve Unified Parkinson's Disease Rating Scale Part III score, selected gait initiation parameters or gait performance in either project. Combined results from both projects suggest that 16 weeks of class-based Tai Chi were ineffective in improving either gait initiation, gait performance, or reducing parkinsonian disability in this subset of persons with PD. Thus the use of short-term Tai Chi exercise should require further study before being considered a valuable therapeutic intervention for these domains in PD.

  20. The Effect of Tai Chi Exercise on Gait Initiation and Gait Performance in Persons with Parkinson’s Disease

    PubMed Central

    Amano, Shinichi; Nocera, Joe R.; Vallabhajosula, Srikant; Juncos, Jorge L.; Gregor, Robert J.; Waddell, Dwight E.; Wolf, Steven L.; Hass, Chris J.

    2013-01-01

    Gait dysfunction and postural instability are two debilitating symptoms in persons with Parkinson’s disease (PD). Tai Chi exercise has recently gained attention as an attractive intervention for persons with PD because of its known potential to reduce falls and improve postural control, walking abilities, and safety at a low cost. The purpose of this report is to investigate the effect of Tai Chi exercise on dynamic postural control during gait initiation and gait performance in persons with idiopathic PD, and to determine whether these benefits could be replicated in two different environments, as complementary projects. In these two separate projects, a total of 45 participants with PD were randomly assigned to either a Tai Chi group or a control group. The Tai Chi groups in both projects completed a 16-week Tai Chi exercise session, while the control groups consisted of either a placebo (i.e., Qi-Gong) or non-exercise group. Tai Chi did not significantly improve Unified Parkinson’s Disease Rating Scale Part III score, selected gait initiation parameters or gait performance in either project. Combined results from both projects suggest that 16 weeks of class-based Tai Chi were ineffective in improving either gait initiation, gait performance, or reducing parkinsonian disability in this subset of persons with PD. Thus the use of short-term Tai Chi exercise should require further study before being considered a valuable therapeutic intervention for these domains in PD. PMID:23835431

  1. A robust real-time gait event detection using wireless gyroscope and its application on normal and altered gaits.

    PubMed

    Gouwanda, Darwin; Gopalai, Alpha Agape

    2015-02-01

    Gait events detection allows clinicians and biomechanics researchers to determine timing of gait events, to estimate duration of stance phase and swing phase and to segment gait data. It also aids biomedical engineers to improve the design of orthoses and FES (functional electrical stimulation) systems. In recent years, researchers have resorted to using gyroscopes to determine heel-strike (HS) and toe-off (TO) events in gait cycles. However, these methods are subjected to significant delays when implemented in real-time gait monitoring devices, orthoses, and FES systems. Therefore, the work presented in this paper proposes a method that addresses these delays, to ensure real-time gait event detection. The proposed algorithm combines the use of heuristics and zero-crossing method to identify HS and TO. Experiments involving: (1) normal walking; (2) walking with knee brace; and (3) walking with ankle brace for overground walking and treadmill walking were designed to verify and validate the identified HS and TO. The performance of the proposed method was compared against the established gait detection algorithms. It was observed that the proposed method produced detection rate that was comparable to earlier reported methods and recorded reduced time delays, at an average of 100 ms. PMID:25619613

  2. Alternative energy efficient membrane bioreactor using reciprocating submerged membrane.

    PubMed

    Ho, J; Smith, S; Roh, H K

    2014-01-01

    A novel membrane bioreactor (MBR) pilot system, using membrane reciprocation instead of air scouring, was operated at constant high flux and daily fluctuating flux to demonstrate its application under peak and diurnal flow conditions. Low and stable transmembrane pressure was achieved at 40 l/m(2)/h (LMH) by use of repetitive membrane reciprocation. The results reveal that the inertial forces acting on the membrane fibers effectively propel foulants from the membrane surface. Reciprocation of the hollow fiber membrane is beneficial for the constant removal of solids that may build up on the membrane surface and inside the membrane bundle. The membrane reciprocation in the reciprocating MBR pilot consumed less energy than coarse air scouring used in conventional MBR systems. Specific energy consumption for the membrane reciprocation was 0.072 kWh/m(3) permeate produced at 40 LMH flux, which is 75% less than for a conventional air scouring system as reported in literature without consideration of energy consumption for biological aeration (0.29 kWh/m(3)). The daily fluctuating flux test confirmed that the membrane reciprocation is effective to handle fluctuating flux up to 50 LMH. The pilot-scale reciprocating MBR system successfully demonstrated that fouling can be controlled via 0.43 Hz membrane reciprocation with 44 mm or higher amplitude.

  3. Institutionalize Reciprocity to Overcome the Public Goods Provision Problem.

    PubMed

    Ozono, Hiroki; Kamijo, Yoshio; Shimizu, Kazumi

    2016-01-01

    Cooperation is fundamental to human societies, and one of the important paths for its emergence and maintenance is reciprocity. In prisoner's dilemma (PD) experiments, reciprocal strategies are often effective at attaining and maintaining high cooperation. In many public goods (PG) games or n-person PD experiments, however, reciprocal strategies are not successful at engendering cooperation. In the present paper, we attribute this difficulty to a coordination problem against free riding among reciprocators: Because it is difficult for the reciprocators to coordinate their behaviors against free riders, this may lead to inequality among players, which will demotivate them from cooperating in future rounds. We propose a new mechanism, institutionalized reciprocity (IR), which refers to embedding the reciprocal strategy as an institution (i.e., institutionalizing the reciprocal strategy). We experimentally demonstrate that IR can prevent groups of reciprocators from falling into coordination failure and achieve high cooperation in PG games. In conclusion, we argue that a natural extension of the present study will be to investigate the possibility of IR to serve as a collective punishment system.

  4. 32 CFR 634.16 - Reciprocal state-military action.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... DMV(s) per reciprocal agreements. In the absence of electronic communication technology, the... licensing authorities. Upon receipt of written or other official law enforcement communication relative...

  5. 32 CFR 634.16 - Reciprocal state-military action.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... DMV(s) per reciprocal agreements. In the absence of electronic communication technology, the... licensing authorities. Upon receipt of written or other official law enforcement communication relative...

  6. 32 CFR 634.16 - Reciprocal state-military action.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... DMV(s) per reciprocal agreements. In the absence of electronic communication technology, the... licensing authorities. Upon receipt of written or other official law enforcement communication relative...

  7. 32 CFR 634.16 - Reciprocal state-military action.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... DMV(s) per reciprocal agreements. In the absence of electronic communication technology, the... licensing authorities. Upon receipt of written or other official law enforcement communication relative...

  8. Alternative energy efficient membrane bioreactor using reciprocating submerged membrane.

    PubMed

    Ho, J; Smith, S; Roh, H K

    2014-01-01

    A novel membrane bioreactor (MBR) pilot system, using membrane reciprocation instead of air scouring, was operated at constant high flux and daily fluctuating flux to demonstrate its application under peak and diurnal flow conditions. Low and stable transmembrane pressure was achieved at 40 l/m(2)/h (LMH) by use of repetitive membrane reciprocation. The results reveal that the inertial forces acting on the membrane fibers effectively propel foulants from the membrane surface. Reciprocation of the hollow fiber membrane is beneficial for the constant removal of solids that may build up on the membrane surface and inside the membrane bundle. The membrane reciprocation in the reciprocating MBR pilot consumed less energy than coarse air scouring used in conventional MBR systems. Specific energy consumption for the membrane reciprocation was 0.072 kWh/m(3) permeate produced at 40 LMH flux, which is 75% less than for a conventional air scouring system as reported in literature without consideration of energy consumption for biological aeration (0.29 kWh/m(3)). The daily fluctuating flux test confirmed that the membrane reciprocation is effective to handle fluctuating flux up to 50 LMH. The pilot-scale reciprocating MBR system successfully demonstrated that fouling can be controlled via 0.43 Hz membrane reciprocation with 44 mm or higher amplitude. PMID:25521136

  9. Institutionalize Reciprocity to Overcome the Public Goods Provision Problem.

    PubMed

    Ozono, Hiroki; Kamijo, Yoshio; Shimizu, Kazumi

    2016-01-01

    Cooperation is fundamental to human societies, and one of the important paths for its emergence and maintenance is reciprocity. In prisoner's dilemma (PD) experiments, reciprocal strategies are often effective at attaining and maintaining high cooperation. In many public goods (PG) games or n-person PD experiments, however, reciprocal strategies are not successful at engendering cooperation. In the present paper, we attribute this difficulty to a coordination problem against free riding among reciprocators: Because it is difficult for the reciprocators to coordinate their behaviors against free riders, this may lead to inequality among players, which will demotivate them from cooperating in future rounds. We propose a new mechanism, institutionalized reciprocity (IR), which refers to embedding the reciprocal strategy as an institution (i.e., institutionalizing the reciprocal strategy). We experimentally demonstrate that IR can prevent groups of reciprocators from falling into coordination failure and achieve high cooperation in PG games. In conclusion, we argue that a natural extension of the present study will be to investigate the possibility of IR to serve as a collective punishment system. PMID:27248493

  10. Institutionalize Reciprocity to Overcome the Public Goods Provision Problem

    PubMed Central

    2016-01-01

    Cooperation is fundamental to human societies, and one of the important paths for its emergence and maintenance is reciprocity. In prisoner’s dilemma (PD) experiments, reciprocal strategies are often effective at attaining and maintaining high cooperation. In many public goods (PG) games or n-person PD experiments, however, reciprocal strategies are not successful at engendering cooperation. In the present paper, we attribute this difficulty to a coordination problem against free riding among reciprocators: Because it is difficult for the reciprocators to coordinate their behaviors against free riders, this may lead to inequality among players, which will demotivate them from cooperating in future rounds. We propose a new mechanism, institutionalized reciprocity (IR), which refers to embedding the reciprocal strategy as an institution (i.e., institutionalizing the reciprocal strategy). We experimentally demonstrate that IR can prevent groups of reciprocators from falling into coordination failure and achieve high cooperation in PG games. In conclusion, we argue that a natural extension of the present study will be to investigate the possibility of IR to serve as a collective punishment system. PMID:27248493

  11. The sequence effect and gait festination in Parkinson disease: contributors to freezing of gait?

    PubMed

    Iansek, Robert; Huxham, Frances; McGinley, Jennifer

    2006-09-01

    Festination and freezing of gait (FOG) are poorly understood gait disorders that cause disability and falls in people with Parkinson disease (PD). In PD, basal ganglia malfunction leads to motor set deficits (hypokinesia), while altered motor cue production leads to a sequence effect, whereby movements becomes progressively smaller as in festination. We suggest both factors may contribute to FOG. Disturbance of set maintenance by the basal ganglia in PD has previously been examined in gait, but limited systematic evaluation of the sequence effect exists. In this study, we investigated the step-to-step amplitude relationship in 10 PD subjects with clinical evidence of festination and FOG. Four conditions were examined: off levodopa, off with attentional strategies, off with visual cues, and on levodopa. Participants demonstrated a sequence effect (F = 6.24; P = 0.001), which was reversed only by use of visual cues. In contrast, medication, attentional strategies, and visual cues all improved hypokinesia. Variability was marked both within and between participants in all conditions. The variability of FOG is suggested to relate to a combination of factors, including the sequence effect and its variability, as well as the severity of hypokinesia and its response to medications. PMID:16773644

  12. Proximal placement of lateral thigh skin markers reduces soft tissue artefact during normal gait using the Conventional Gait Model.

    PubMed

    Cockcroft, John; Louw, Quinette; Baker, Richard

    2016-11-01

    A primary source of measurement error in gait analysis is soft-tissue artefact. Hip and knee angle measurements, regularly used in clinical decision-making, are particularly prone to pervasive soft tissue on the femur. However, despite several studies of thigh marker artefact it remains unclear how lateral thigh marker height affects results using variants of the Conventional Gait Model. We compared Vicon Plug-in Gait hip and knee angle estimates during gait using a proximal and distal thigh marker placement for ten healthy subjects. Knee axes were estimated by optimizing thigh rotation offsets to minimize knee varus-valgus range during gait. Relative to the distal marker, the proximal marker produced 37% less varus-valgus range and 50% less hip rotation range (p < 0.001), suggesting that it produced less soft-tissue artefact in knee axis estimates. The thigh markers also produced different secondary effects on the knee centre estimate. Using whole gait cycle optimization, the distal marker showed greater minimum and maximum knee flexion (by 6° and 2° respectively) resulting in a 4° reduction in range. Mid-stance optimization reduced distal marker knee flexion by 5° throughout, but proximal marker results were negligibly affected. Based on an analysis of the Plug-in Gait knee axis definition, we show that the proximal marker reduced sensitivity to soft-tissue artefact by decreasing collinearity between the points defining the femoral frontal plane and reducing anteroposterior movement between the knee and thigh markers. This study suggests that a proximal thigh marker may be preferable when performing gait analysis using the Plug-in Gait model.

  13. Proximal placement of lateral thigh skin markers reduces soft tissue artefact during normal gait using the Conventional Gait Model.

    PubMed

    Cockcroft, John; Louw, Quinette; Baker, Richard

    2016-11-01

    A primary source of measurement error in gait analysis is soft-tissue artefact. Hip and knee angle measurements, regularly used in clinical decision-making, are particularly prone to pervasive soft tissue on the femur. However, despite several studies of thigh marker artefact it remains unclear how lateral thigh marker height affects results using variants of the Conventional Gait Model. We compared Vicon Plug-in Gait hip and knee angle estimates during gait using a proximal and distal thigh marker placement for ten healthy subjects. Knee axes were estimated by optimizing thigh rotation offsets to minimize knee varus-valgus range during gait. Relative to the distal marker, the proximal marker produced 37% less varus-valgus range and 50% less hip rotation range (p < 0.001), suggesting that it produced less soft-tissue artefact in knee axis estimates. The thigh markers also produced different secondary effects on the knee centre estimate. Using whole gait cycle optimization, the distal marker showed greater minimum and maximum knee flexion (by 6° and 2° respectively) resulting in a 4° reduction in range. Mid-stance optimization reduced distal marker knee flexion by 5° throughout, but proximal marker results were negligibly affected. Based on an analysis of the Plug-in Gait knee axis definition, we show that the proximal marker reduced sensitivity to soft-tissue artefact by decreasing collinearity between the points defining the femoral frontal plane and reducing anteroposterior movement between the knee and thigh markers. This study suggests that a proximal thigh marker may be preferable when performing gait analysis using the Plug-in Gait model. PMID:26929983

  14. Gait rehabilitation with a high tech platform based on virtual reality conveys improvements in walking ability of children suffering from acquired brain injury.

    PubMed

    Biffi, E; Beretta, E; Diella, E; Panzeri, D; Maghini, C; Turconi, A C; Strazzer, S; Reni, G

    2015-01-01

    The Gait Real-time Analysis Interactive Lab (GRAIL) is an instrumented multi-sensor platform based on immersive virtual reality for gait training and rehabilitation. Few studies have been included GRAIL to evaluate gait patterns in normal and disabled people and to improve gait in adults, while at our knowledge no evidence on its use for the rehabilitation of children is available. In this study, 4 children suffering from acquired brain injury (ABI) underwent a 5 session treatment with GRAIL, to improve walking and balance ability in engaging VR environments. The first and the last sessions were partially dedicated to gait evaluation. Results are promising: improvements were recorded at the ankle level, selectively at the affected side, and at the pelvic level, while small changes were measured at the hip and knee joints, which were already comparable to healthy subjects. All these changes also conveyed advances in the symmetry of the walking pattern. In the next future, a longer intervention will be proposed and more children will be enrolled to strongly prove the effectiveness of GRAIL in the rehabilitation of children with ABI.

  15. [How acrophobia impairs visual exploration and gait].

    PubMed

    Kugler, G; Huppert, D; Schneider, E; Brandt, T

    2013-10-01

    The life-time prevalence of visual height intolerance is 28 % in the general population. More than 50 % of those affected suffer from an impairment of daily behavior and quality of life when confronted with heights. Simultaneous measurements of spontaneous eye and head movements of these subjects while looking from a balcony revealed that visual exploration of the surroundings was restricted compared to that of control subjects. Spontaneous head movements were severely diminished and saccadic eye movements were reduced. Gaze in space was preferably directed towards structures on the horizon. Those susceptible to visual height intolerance exhibited a cautious slowing of gait with small and precarious steps. Restriction of visual exploration during locomotion in a complex terrain may result in falls because obstacles can be overlooked. PMID:24057067

  16. [How acrophobia impairs visual exploration and gait].

    PubMed

    Kugler, G; Huppert, D; Schneider, E; Brandt, T

    2013-10-01

    The life-time prevalence of visual height intolerance is 28 % in the general population. More than 50 % of those affected suffer from an impairment of daily behavior and quality of life when confronted with heights. Simultaneous measurements of spontaneous eye and head movements of these subjects while looking from a balcony revealed that visual exploration of the surroundings was restricted compared to that of control subjects. Spontaneous head movements were severely diminished and saccadic eye movements were reduced. Gaze in space was preferably directed towards structures on the horizon. Those susceptible to visual height intolerance exhibited a cautious slowing of gait with small and precarious steps. Restriction of visual exploration during locomotion in a complex terrain may result in falls because obstacles can be overlooked.

  17. Understanding the complexity of human gait dynamics

    NASA Astrophysics Data System (ADS)

    Scafetta, Nicola; Marchi, Damiano; West, Bruce J.

    2009-06-01

    Time series of human gait stride intervals exhibit fractal and multifractal properties under several conditions. Records from subjects walking at normal, slow, and fast pace speed are analyzed to determine changes in the fractal scalings as a function of the stress condition of the system. Records from subjects with different age from children to elderly and patients suffering from neurodegenerative disease are analyzed to determine changes in the fractal scalings as a function of the physical maturation or degeneration of the system. A supercentral pattern generator model is presented to simulate the above two properties that are typically found in dynamical network performance: that is, how a dynamical network responds to stress and to evolution.

  18. Understanding the complexity of human gait dynamics.

    PubMed

    Scafetta, Nicola; Marchi, Damiano; West, Bruce J

    2009-06-01

    Time series of human gait stride intervals exhibit fractal and multifractal properties under several conditions. Records from subjects walking at normal, slow, and fast pace speed are analyzed to determine changes in the fractal scalings as a function of the stress condition of the system. Records from subjects with different age from children to elderly and patients suffering from neurodegenerative disease are analyzed to determine changes in the fractal scalings as a function of the physical maturation or degeneration of the system. A supercentral pattern generator model is presented to simulate the above two properties that are typically found in dynamical network performance: that is, how a dynamical network responds to stress and to evolution. PMID:19566268

  19. Fractal and Multifractal Analysis of Human Gait

    NASA Astrophysics Data System (ADS)

    Muñoz-Diosdado, A.; del Río Correa, J. L.; Angulo-Brown, F.

    2003-09-01

    We carried out a fractal and multifractal analysis of human gait time series of young and old individuals, and adults with three illnesses that affect the march: The Parkinson's and Huntington's diseases and the amyotrophic lateral sclerosis (ALS). We obtained cumulative plots of events, the correlation function, the Hurst exponent and the Higuchi's fractal dimension of these time series and found that these fractal markers could be a factor to characterize the march, since we obtained different values of these quantities for youths and adults and they are different also for healthy and ill persons and the most anomalous values belong to ill persons. In other physiological signals there is complexity lost related with the age and the illness, in the case of the march the opposite occurs. The multifractal analysis could be also a useful tool to understand the dynamics of these and other complex systems.

  20. Reciprocating piston pump system with screw drive

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor); Moore, Nicholas R. (Inventor)

    1981-01-01

    A pump system of the reciprocating piston type is described, which facilitates direct motor drive and cylinder sealing. A threaded middle potion of the piston is engaged by a nut connected to rotate with the rotor of an electric motor, in a manner that minimizes loading on the rotor by the use of a coupling that transmits torque to the nut but permits it to shift axially and radially with respect to the rotor. The nut has a threaded hydrostatic bearing for engaging the threaded piston portion, with an oil-carrying groove in the nut being interrupted. A fluid emitting seal located at the entrance to each cylinder, can serve to center the piston within the cylinder, wash the piston, and to aid in sealing. The piston can have a long stroke to diameter ratio to minimize reciprocations and wear on valves at high pressures. The voltage applied to the motor can be reversed prior to the piston reaching the end of its stroke, to permit pressure on the piston to aid in reversing the motor.

  1. [Gait disorders in Parkinson disease. Clinical description, analysis of posture, initiation of stabilized gait].

    PubMed

    Kemoun, G; Defebvre, L

    2001-03-10

    A WELL INFORMED DESCRIPTION: The parkinsonian posture is generally described as a stooped one. At the beginning of the disease, the gait troubles remain moderate; gradually the gait is composed of small steps without a wide base; the patient tends to run after his centre of gravity by accelerating the step (festination phenomenon). Difficulties occurs for starting up (delay of gait initiation), for about-turn or for clearing obstacles. Kinetic jammings and standing around (freezing) can last several seconds and be responsible for falls. POSTURAL INSTABILITY, A MAJOR SYMPTOM IN PARKINSON'S DISEASE: This symptom is little improved by therapies and is responsible for serious disability. Postural instability induces a disequilibrium and is partially due to a simultaneous antagonist muscles contraction and to the impossibility of modifying postural responses to changing support conditions. The passive viscoelastic properties of muscles and tendons constitute a first line of defence against the disequilibrium and contribute to postural stability in the case of medium disturbances. Automatic and voluntary postural responses which come into play in the case of major disturbances can also be impaired (delay or defect of the responses). GAIT INITIATION FAILURE ARE FREQUENT: They result from an increase of the postural phase and a decrease of the propulsion forces, depending on a deficit of the postural anticipation mechanisms and also the sequential organization and the integration of two different motor programs, postural and locomotor. They can be controlled partially with sensory stimuli, notably visual inputs. DATA CONCERNING STABILIZED WALKING AND ITS PATHOPHYSIOLOGY REMAINS TO BE CLARIFIED: Spatial and temporal parameters are impaired: speed, step length and swing phase are reduced, while cadence increases to compensate these troubles. These modifications are the consequence of an incapacity to produce internal marks to generate regular steps. When the parkinsonian

  2. Low Power Shoe Integrated Intelligent Wireless Gait Measurement System

    NASA Astrophysics Data System (ADS)

    Wahab, Y.; Mazalan, M.; Bakar, N. A.; Anuar, A. F.; Zainol, M. Z.; Hamzah, F.

    2014-04-01

    Gait analysis measurement is a method to assess and identify gait events and the measurements of dynamic, motion and pressure parameters involving the lowest part of the body. This significant analysis is widely used in sports, rehabilitation as well as other health diagnostic towards improving the quality of life. This paper presents a new system empowered by Inertia Measurement Unit (IMU), ultrasonic sensors, piezoceramic sensors array, XBee wireless modules and Arduino processing unit. This research focuses on the design and development of a low power ultra-portable shoe integrated wireless intelligent gait measurement using MEMS and recent microelectronic devices for foot clearance, orientation, error correction, gait events and pressure measurement system. It is developed to be cheap, low power, wireless, real time and suitable for real life in-door and out-door environment.

  3. Scientists Zero in On Brain Area Linked to 'Parkinson's Gait'

    MedlinePlus

    ... Scientists Zero in on Brain Area Linked to 'Parkinson's Gait' Discovery could lead to new treatments for ... play a role in walking difficulties that afflict Parkinson's disease patients, new research suggests. The prefrontal cortex ...

  4. Interpolation function for approximating knee joint behavior in human gait

    NASA Astrophysics Data System (ADS)

    Toth-Taşcǎu, Mirela; Pater, Flavius; Stoia, Dan Ioan

    2013-10-01

    Starting from the importance of analyzing the kinematic data of the lower limb in gait movement, especially the angular variation of the knee joint, the paper propose an approximation function that can be used for processing the correlation among a multitude of knee cycles. The approximation of the raw knee data was done by Lagrange polynomial interpolation on a signal acquired using Zebris Gait Analysis System. The signal used in approximation belongs to a typical subject extracted from a lot of ten investigated subjects, but the function domain of definition belongs to the entire group. The study of the knee joint kinematics plays an important role in understanding the kinematics of the gait, this articulation having the largest range of motion in whole joints, in gait. The study does not propose to find an approximation function for the adduction-abduction movement of the knee, this being considered a residual movement comparing to the flexion-extension.

  5. Measuring gait using a ground laser range sensor.

    PubMed

    Pallejà, Tomàs; Teixidó, Mercè; Tresanchez, Marcel; Palacín, Jordi

    2009-01-01

    This paper describes a measurement system designed to register the displacement of the legs using a two-dimensional laser range sensor with a scanning plane parallel to the ground and extract gait parameters. In the proposed methodology, the position of the legs is estimated by fitting two circles with the laser points that define their contour and the gait parameters are extracted applying a step-line model to the estimated displacement of the legs to reduce uncertainty in the determination of the stand and swing phase of the gait. Results obtained in a range up to 8 m shows that the systematic error in the location of one static leg is lower than 10 mm with and standard deviation lower than 8 mm; this deviation increases to 11 mm in the case of a moving leg. The proposed measurement system has been applied to estimate the gait parameters of six volunteers in a preliminary walking experiment. PMID:22291558

  6. Gait-based person recognition using arbitrary view transformation model.

    PubMed

    Muramatsu, Daigo; Shiraishi, Akira; Makihara, Yasushi; Uddin, Md Zasim; Yagi, Yasushi

    2015-01-01

    Gait recognition is a useful biometric trait for person authentication because it is usable even with low image resolution. One challenge is robustness to a view change (cross-view matching); view transformation models (VTMs) have been proposed to solve this. The VTMs work well if the target views are the same as their discrete training views. However, the gait traits are observed from an arbitrary view in a real situation. Thus, the target views may not coincide with discrete training views, resulting in recognition accuracy degradation. We propose an arbitrary VTM (AVTM) that accurately matches a pair of gait traits from an arbitrary view. To realize an AVTM, we first construct 3D gait volume sequences of training subjects, disjoint from the test subjects in the target scene. We then generate 2D gait silhouette sequences of the training subjects by projecting the 3D gait volume sequences onto the same views as the target views, and train the AVTM with gait features extracted from the 2D sequences. In addition, we extend our AVTM by incorporating a part-dependent view selection scheme (AVTM_PdVS), which divides the gait feature into several parts, and sets part-dependent destination views for transformation. Because appropriate destination views may differ for different body parts, the part-dependent destination view selection can suppress transformation errors, leading to increased recognition accuracy. Experiments using data sets collected in different settings show that the AVTM improves the accuracy of cross-view matching and that the AVTM_PdVS further improves the accuracy in many cases, in particular, verification scenarios. PMID:25423652

  7. Gait Using Pneumatic Brace for End-Stage Knee Osteoarthritis.

    PubMed

    Kapadia, Bhaveen H; Cherian, Jeffrey Jai; Starr, Roland; Chughtai, Morad; Mont, Michael A; Harwin, Steven F; Bhave, Anil

    2016-04-01

    More than 20 million individuals in the United States are affected by knee osteoarthritis (OA), which can lead to altered biomechanics and excessive joint loading. The use of an unloader pneumatic brace with extension assist has been proposed as a nonoperative treatment modality that may improve gait mechanics and correct knee malalignment. We assessed the following parameters in patients who have knee OA treated with and without a brace: (1) changes in temporospatial parameters in gait; (2) knee range of motion, knee extension at heel strike, and foot placement; (3) knee joint moments and impulse; and (4) changes in dynamic stiffness and rate of change of knee flexion during midstance to terminal stance. This 2:1 prospective, randomized, single-blinded trial evaluated 36 patients (24 brace and 12 matching). OA knee patients were randomized to receive either a pneumatic unloader brace or a standard nonoperative treatment regimen as the matching cohort for a 3-month period. They underwent evaluation of gait parameters using a three-dimensional gait analysis system at their initial appointment and at 3 months follow-up. All the testing, pre- and postbracing were performed without wearing the brace to examine for retained effects. Treatment with the brace led to significant improvements versus standard treatment in various gait parameters. Patients in the brace group had improvements in walking speed, knee extension at heel strike, total range of motion, knee joint forces, and rate of knee flexion from midstance to terminal stance when compared with the matching cohort. Knee OA patients who used a pneumatic unloader brace for 3 months for at least 3 hours per day had significant improvements various gait parameters when compared with a standard nonoperative therapy cohort. Braced patients demonstrated gait-modifying affects when not wearing the brace. These results are encouraging and suggest that this device represents a promising treatment modality for knee OA that

  8. Investigation of factors impacting mobility and gait in Parkinson disease.

    PubMed

    Christofoletti, Gustavo; McNeely, Marie E; Campbell, Meghan C; Duncan, Ryan P; Earhart, Gammon M

    2016-10-01

    Mobility and gait limitations are major issues for people with Parkinson disease (PD). Identification of factors that contribute to these impairments may inform treatment and intervention strategies. In this study we investigated factors that predict mobility and gait impairment in PD. Participants with mild to moderate PD and without dementia (n=114) were tested in one session 'off' medication. Mobility measures included the 6-Minute Walk test and Timed-Up-and-Go. Gait velocity was collected in four conditions: forward preferred speed, forward dual task, forward fast as possible and backward walking. The predictors analyzed were age, gender, disease severity, balance, balance confidence, fall history, self-reported physical activity, and executive function. Multiple regression models were used to assess the relationships between predictors and outcomes. The predictors, in different combinations for each outcome measure, explained 55.7% to 66.9% of variability for mobility and 39.5% to 52.8% for gait velocity. Balance was the most relevant factor (explaining up to 54.1% of variance in mobility and up to 45.6% in gait velocity). Balance confidence contributed to a lesser extent (2.0% to 8.2% of variance) in all models. Age explained a small percentage of variance in mobility and gait velocity (up to 2.9%). Executive function explained 3.0% of variance during forward walking only. The strong predictive relationships between balance deficits and mobility and gait impairment suggest targeting balance deficits may be particularly important for improving mobility and gait in people with PD, regardless of an individual's age, disease severity, fall history, or other demographic features. PMID:27551818

  9. Gait Patterns in Patients with Hereditary Spastic Paraparesis

    PubMed Central

    Ranavolo, Alberto; Lacquaniti, Francesco; Martino, Giovanni; Leonardi, Luca; Conte, Carmela; Varrecchia, Tiwana; Draicchio, Francesco; Coppola, Gianluca; Casali, Carlo; Pierelli, Francesco

    2016-01-01

    Background Spastic gait is a key feature in patients with hereditary spastic paraparesis, but the gait characterization and the relationship between the gait impairment and clinical characteristics have not been investigated. Objectives To describe the gait patterns in hereditary spastic paraparesis and to identify subgroups of patients according to specific kinematic features of walking. Methods We evaluated fifty patients by computerized gait analysis and compared them to healthy participants. We computed time-distance parameters of walking and the range of angular motion at hip, knee, and ankle joints, and at the trunk and pelvis. Lower limb joint moments and muscle co-activation values were also evaluated. Results We identified three distinct subgroups of patients based on the range of motion values. Subgroup one was characterized by reduced hip, knee, and ankle joint range of motion. These patients were the most severely affected from a clinical standpoint, had the highest spasticity, and walked at the slowest speed. Subgroup three was characterized by an increased hip joint range of motion, but knee and ankle joint range of motion values close to control values. These patients were the most mildly affected and had the highest walking speed. Finally, subgroup two showed reduced knee and ankle joint range of motion, and hip range of motion values close to control values. Disease severity and gait speed in subgroup two were between those of subgroups one and three. Conclusions We identified three distinctive gait patterns in patients with hereditary spastic paraparesis that correlated robustly with clinical data. Distinguishing specific features in the gait patterns of these patients may help tailor pharmacological and rehabilitative treatments and may help evaluate therapeutic effects over time. PMID:27732632

  10. Investigation of factors impacting mobility and gait in Parkinson disease.

    PubMed

    Christofoletti, Gustavo; McNeely, Marie E; Campbell, Meghan C; Duncan, Ryan P; Earhart, Gammon M

    2016-10-01

    Mobility and gait limitations are major issues for people with Parkinson disease (PD). Identification of factors that contribute to these impairments may inform treatment and intervention strategies. In this study we investigated factors that predict mobility and gait impairment in PD. Participants with mild to moderate PD and without dementia (n=114) were tested in one session 'off' medication. Mobility measures included the 6-Minute Walk test and Timed-Up-and-Go. Gait velocity was collected in four conditions: forward preferred speed, forward dual task, forward fast as possible and backward walking. The predictors analyzed were age, gender, disease severity, balance, balance confidence, fall history, self-reported physical activity, and executive function. Multiple regression models were used to assess the relationships between predictors and outcomes. The predictors, in different combinations for each outcome measure, explained 55.7% to 66.9% of variability for mobility and 39.5% to 52.8% for gait velocity. Balance was the most relevant factor (explaining up to 54.1% of variance in mobility and up to 45.6% in gait velocity). Balance confidence contributed to a lesser extent (2.0% to 8.2% of variance) in all models. Age explained a small percentage of variance in mobility and gait velocity (up to 2.9%). Executive function explained 3.0% of variance during forward walking only. The strong predictive relationships between balance deficits and mobility and gait impairment suggest targeting balance deficits may be particularly important for improving mobility and gait in people with PD, regardless of an individual's age, disease severity, fall history, or other demographic features.

  11. Gait Characteristic Analysis and Identification Based on the iPhone's Accelerometer and Gyrometer

    PubMed Central

    Sun, Bing; Wang, Yang; Banda, Jacob

    2014-01-01

    Gait identification is a valuable approach to identify humans at a distance. In this paper, gait characteristics are analyzed based on an iPhone's accelerometer and gyrometer, and a new approach is proposed for gait identification. Specifically, gait datasets are collected by the triaxial accelerometer and gyrometer embedded in an iPhone. Then, the datasets are processed to extract gait characteristic parameters which include gait frequency, symmetry coefficient, dynamic range and similarity coefficient of characteristic curves. Finally, a weighted voting scheme dependent upon the gait characteristic parameters is proposed for gait identification. Four experiments are implemented to validate the proposed scheme. The attitude and acceleration solutions are verified by simulation. Then the gait characteristics are analyzed by comparing two sets of actual data, and the performance of the weighted voting identification scheme is verified by 40 datasets of 10 subjects. PMID:25222034

  12. Hysteresis in the metachronal-tripod gait transition of insects: a modeling study.

    PubMed

    Fujiki, Soichiro; Aoi, Shinya; Funato, Tetsuro; Tomita, Nozomi; Senda, Kei; Tsuchiya, Kazuo

    2013-07-01

    Locomotion in biological systems involves various gaits, and hysteresis appears when the gaits change in accordance with the locomotion speed. That is, the gaits vary at different locomotion speeds depending on the direction of speed change. Although hysteresis is a typical characteristic of nonlinear dynamic systems, the underlying mechanism for the hysteresis in gait transitions remains largely unclear. In this study, we construct a neuromechanical model of an insect and investigate the dynamic characteristics of its gait and gait transition. The simulation results show that our insect model produces metachronal and tripod gaits depending on the locomotion speed through dynamic interactions among the body mechanical system, the nervous system, and the environment in a self-organized manner. They also show that it undergoes the metachronal-tripod gait transition with hysteresis by changing the locomotion speed. We examined the hysteresis mechanism in the metachronal-tripod gait transition of insects from a dynamic viewpoint.

  13. Hysteresis in the metachronal-tripod gait transition of insects: A modeling study

    NASA Astrophysics Data System (ADS)

    Fujiki, Soichiro; Aoi, Shinya; Funato, Tetsuro; Tomita, Nozomi; Senda, Kei; Tsuchiya, Kazuo

    2013-07-01

    Locomotion in biological systems involves various gaits, and hysteresis appears when the gaits change in accordance with the locomotion speed. That is, the gaits vary at different locomotion speeds depending on the direction of speed change. Although hysteresis is a typical characteristic of nonlinear dynamic systems, the underlying mechanism for the hysteresis in gait transitions remains largely unclear. In this study, we construct a neuromechanical model of an insect and investigate the dynamic characteristics of its gait and gait transition. The simulation results show that our insect model produces metachronal and tripod gaits depending on the locomotion speed through dynamic interactions among the body mechanical system, the nervous system, and the environment in a self-organized manner. They also show that it undergoes the metachronal-tripod gait transition with hysteresis by changing the locomotion speed. We examined the hysteresis mechanism in the metachronal-tripod gait transition of insects from a dynamic viewpoint.

  14. Validity of the Kinect for Gait Assessment: A Focused Review.

    PubMed

    Springer, Shmuel; Yogev Seligmann, Galit

    2016-02-04

    Gait analysis may enhance clinical practice. However, its use is limited due to the need for expensive equipment which is not always available in clinical settings. Recent evidence suggests that Microsoft Kinect may provide a low cost gait analysis method. The purpose of this report is to critically evaluate the literature describing the concurrent validity of using the Kinect as a gait analysis instrument. An online search of PubMed, CINAHL, and ProQuest databases was performed. Included were studies in which walking was assessed with the Kinect and another gold standard device, and consisted of at least one numerical finding of spatiotemporal or kinematic measures. Our search identified 366 papers, from which 12 relevant studies were retrieved. The results demonstrate that the Kinect is valid only for some spatiotemporal gait parameters. Although the kinematic parameters measured by the Kinect followed the trend of the joint trajectories, they showed poor validity and large errors. In conclusion, the Kinect may have the potential to be used as a tool for measuring spatiotemporal aspects of gait, yet standardized methods should be established, and future examinations with both healthy subjects and clinical participants are required in order to integrate the Kinect as a clinical gait analysis tool.

  15. Self-calibrating view-invariant gait biometrics.

    PubMed

    Goffredo, Michela; Bouchrika, Imed; Carter, John N; Nixon, Mark S

    2010-08-01

    We present a new method for viewpoint independent gait biometrics. The system relies on a single camera, does not require camera calibration, and works with a wide range of camera views. This is achieved by a formulation where the gait is self-calibrating. These properties make the proposed method particularly suitable for identification by gait, where the advantages of completely unobtrusiveness, remoteness, and covertness of the biometric system preclude the availability of camera information and specific walking directions. The approach has been assessed for feature extraction and recognition capabilities on the SOTON gait database and then evaluated on a multiview database to establish recognition capability with respect to view invariance. Moreover, tests on the multiview CASIA-B database, composed of more than 2270 video sequences with 65 different subjects walking freely along different walking directions, have been performed. The obtained results show that human identification by gait can be achieved without any knowledge of internal or external camera parameters with a mean correct classification rate of 73.6% across all views using purely dynamic gait features. The performance of the proposed method is particularly encouraging for application in surveillance scenarios.

  16. FreeWalker: a smart insole for longitudinal gait analysis.

    PubMed

    Wang, Baitong; Rajput, Kuldeep Singh; Tam, Wing-Kin; Tung, Anthony K H; Yang, Zhi

    2015-08-01

    Gait analysis is an important diagnostic measure to investigate the pattern of walking. Traditional gait analysis is generally carried out in a gait lab, with equipped force and body tracking sensors, which needs a trained medical professional to interpret the results. This procedure is tedious, expensive, and unreliable and makes it difficult to track the progress across multiple visits. In this paper, we present a smart insole called FreeWalker, which provides quantitative gait analysis outside the confinement of traditional lab, at low- cost. The insole consists of eight pressure sensors and two motion tracking sensors, i.e. 3-axis accelerometer and 3-axis gyroscope. This enables measurement of under-foot pressure distribution and motion sequences in real-time. The insole is enabled with onboard SD card as well as wireless data transmission, which help in continuous gait-cycle analysis. The data is then sent to a gateway, for analysis and interpretation of data, using a user interface where gait features are graphically displayed. We also present validation result of a subject's left foot, who was asked to perform a specific task. Experiment results show that we could achieve a data-sampling rate of over 1 KHz, transmitting data up to a distance of 20 meter and maintain a battery life of around 24 hours. Taking advantage of these features, FreeWalker can be used in various applications, like medical diagnosis, rehabilitation, sports and entertainment. PMID:26737102

  17. Quantifying dynamic characteristics of human walking for comprehensive gait cycle.

    PubMed

    Mummolo, Carlotta; Mangialardi, Luigi; Kim, Joo H

    2013-09-01

    Normal human walking typically consists of phases during which the body is statically unbalanced while maintaining dynamic stability. Quantifying the dynamic characteristics of human walking can provide better understanding of gait principles. We introduce a novel quantitative index, the dynamic gait measure (DGM), for comprehensive gait cycle. The DGM quantifies the effects of inertia and the static balance instability in terms of zero-moment point and ground projection of center of mass and incorporates the time-varying foot support region (FSR) and the threshold between static and dynamic walking. Also, a framework of determining the DGM from experimental data is introduced, in which the gait cycle segmentation is further refined. A multisegmental foot model is integrated into a biped system to reconstruct the walking motion from experiments, which demonstrates the time-varying FSR for different subphases. The proof-of-concept results of the DGM from a gait experiment are demonstrated. The DGM results are analyzed along with other established features and indices of normal human walking. The DGM provides a measure of static balance instability of biped walking during each (sub)phase as well as the entire gait cycle. The DGM of normal human walking has the potential to provide some scientific insights in understanding biped walking principles, which can also be useful for their engineering and clinical applications.

  18. Adaptive changes in spatiotemporal gait characteristics in women during pregnancy.

    PubMed

    Błaszczyk, Janusz W; Opala-Berdzik, Agnieszka; Plewa, Michał

    2016-01-01

    Spatiotemporal gait cycle characteristics were assessed at early (P1), and late (P2) pregnancy, as well as at 2 months (PP1) and 6 months (PP2) postpartum. A substantial decrease in walking speed was observed throughout the pregnancy, with the slowest speed (1±0.2m/s) being during the third trimester. Walking at slower velocity resulted in complex adaptive adjustments to their spatiotemporal gait pattern, including a shorter step length and an increased duration of both their stance and double-support phases. Duration of the swing phase remained the least susceptible to changes. Habitual walking velocity (1.13±0.2m/s) and the optimal gait pattern were fully recovered 6 months after childbirth. Documented here adaptive changes in the preferred gait pattern seem to result mainly from the altered body anthropometry leading to temporary balance impairments. All the observed changes within stride cycle aimed to improve gait safety by focusing on its dynamic stability. The pregnant women preferred to walk at a slower velocity which allowed them to spend more time in double-support compared with their habitual pattern. Such changes provided pregnant women with a safer and more tentative ambulation that reduced the single-support period and, hence, the possibility of instability. As pregnancy progressed a significant increase in stance width and a decrease in step length was observed. Both factors allow also for gait stability improvement.

  19. Kinetic Gait Analysis Using a Low-Cost Insole.

    PubMed

    Howell, Adam M; Kobayashi, Toshiki; Hayes, Heather A; Foreman, K Bo; Bamberg, Stacy J Morris

    2013-12-01

    Abnormal gait caused by stroke or other pathological reasons can greatly impact the life of an individual. Being able to measure and analyze that gait is often critical for rehabilitation. Motion analysis labs and many current methods of gait analysis are expensive and inaccessible to most individuals. The low-cost, wearable, and wireless insole-based gait analysis system in this study provides kinetic measurements of gait by using low-cost force sensitive resistors. This paper describes the design and fabrication of the insole and its evaluation in six control subjects and four hemiplegic stroke subjects. Subject-specific linear regression models were used to determine ground reaction force plus moments corresponding to ankle dorsiflexion/plantarflexion, knee flexion/extension, and knee abduction/adduction. Comparison with data simultaneously collected from a clinical motion analysis laboratory demonstrated that the insole results for ground reaction force and ankle moment were highly correlated (all >0.95) for all subjects, while the two knee moments were less strongly correlated (generally >0.80). This provides a means of cost-effective and efficient healthcare delivery of mobile gait analysis that can be used anywhere from large clinics to an individual's home.

  20. Efficacy of clinical gait analysis: A systematic review.

    PubMed

    Wren, Tishya A L; Gorton, George E; Ounpuu, Sylvia; Tucker, Carole A

    2011-06-01

    The aim of this systematic review was to evaluate and summarize the current evidence base related to the clinical efficacy of gait analysis. A literature review was conducted to identify references related to human gait analysis published between January 2000 and September 2009 plus relevant older references. The references were assessed independently by four reviewers using a hierarchical model of efficacy adapted for gait analysis, and final scores were agreed upon by at least three of the four reviewers. 1528 references were identified relating to human instrumented gait analysis. Of these, 116 original articles addressed technical accuracy efficacy, 89 addressed diagnostic accuracy efficacy, 11 addressed diagnostic thinking and treatment efficacy, seven addressed patient outcomes efficacy, and one addressed societal efficacy, with some of the articles addressing multiple levels of efficacy. This body of literature provides strong evidence for the technical, diagnostic accuracy, diagnostic thinking and treatment efficacy of gait analysis. The existing evidence also indicates efficacy at the higher levels of patient outcomes and societal cost-effectiveness, but this evidence is more sparse and does not include any randomized controlled trials. Thus, the current evidence supports the clinical efficacy of gait analysis, particularly at the lower levels of efficacy, but additional research is needed to strengthen the evidence base at the higher levels of efficacy.

  1. FreeWalker: a smart insole for longitudinal gait analysis.

    PubMed

    Wang, Baitong; Rajput, Kuldeep Singh; Tam, Wing-Kin; Tung, Anthony K H; Yang, Zhi

    2015-08-01

    Gait analysis is an important diagnostic measure to investigate the pattern of walking. Traditional gait analysis is generally carried out in a gait lab, with equipped force and body tracking sensors, which needs a trained medical professional to interpret the results. This procedure is tedious, expensive, and unreliable and makes it difficult to track the progress across multiple visits. In this paper, we present a smart insole called FreeWalker, which provides quantitative gait analysis outside the confinement of traditional lab, at low- cost. The insole consists of eight pressure sensors and two motion tracking sensors, i.e. 3-axis accelerometer and 3-axis gyroscope. This enables measurement of under-foot pressure distribution and motion sequences in real-time. The insole is enabled with onboard SD card as well as wireless data transmission, which help in continuous gait-cycle analysis. The data is then sent to a gateway, for analysis and interpretation of data, using a user interface where gait features are graphically displayed. We also present validation result of a subject's left foot, who was asked to perform a specific task. Experiment results show that we could achieve a data-sampling rate of over 1 KHz, transmitting data up to a distance of 20 meter and maintain a battery life of around 24 hours. Taking advantage of these features, FreeWalker can be used in various applications, like medical diagnosis, rehabilitation, sports and entertainment.

  2. Gait Planning and Stability Control of a Quadruped Robot

    PubMed Central

    Li, Junmin; Wang, Jinge; Yang, Simon X.; Zhou, Kedong; Tang, Huijuan

    2016-01-01

    In order to realize smooth gait planning and stability control of a quadruped robot, a new controller algorithm based on CPG-ZMP (central pattern generator-zero moment point) is put forward in this paper. To generate smooth gait and shorten the adjusting time of the model oscillation system, a new CPG model controller and its gait switching strategy based on Wilson-Cowan model are presented in the paper. The control signals of knee-hip joints are obtained by the improved multi-DOF reduced order control theory. To realize stability control, the adaptive speed adjustment and gait switch are completed by the real-time computing of ZMP. Experiment results show that the quadruped robot's gaits are efficiently generated and the gait switch is smooth in the CPG control algorithm. Meanwhile, the stability of robot's movement is improved greatly with the CPG-ZMP algorithm. The algorithm in this paper has good practicability, which lays a foundation for the production of the robot prototype. PMID:27143959

  3. Knee Joint Dysfunctions That Influence Gait in Cerebrovascular Injury

    PubMed Central

    Lucareli, Paulo Roberto Garcia; Greve, Julia Maria D’Andrea

    2008-01-01

    INTRODUCTION There is still no consensus among different specialists on the subject of kinematic variation during the hemiparetic gait, including the main changes that take place during the gait cycle and whether the gait velocity changes the patterns of joint mobility. One of the most frequently discussed joints is the knee. OBJECTIVES This study aims to evaluate the variables found in the angular kinematics of knee joint, and to describe the alterations found in the hemiparetic gait resulting from cerebrovascular injury. METHODS This study included 66 adult patients of both genders with a diagnosis of either right or left hemiparesis resulting from ischemic cerebrovascular injury. All the participants underwent three-dimensional gait evaluation, an the angular kinematics of the joint knee were selected for analysis. RESULTS The results were distributed into four groups formed based on the median of the gait speed and the side of hemiparesis. CONCLUSIONS The relevant clinical characteristics included the important mechanisms of loading response in the stance, knee hyperextension in single stance, and reduction of the peak flexion and movement amplitude of the knee in the swing phase. These mechanisms should be taken into account when choosing the best treatment. We believe that the findings presented here may aid in preventing the occurrence of the problems found, and also in identifying the origin of these problems. PMID:18719753

  4. Kinematic gait patterns in healthy runners: A hierarchical cluster analysis.

    PubMed

    Phinyomark, Angkoon; Osis, Sean; Hettinga, Blayne A; Ferber, Reed

    2015-11-01

    Previous studies have demonstrated distinct clusters of gait patterns in both healthy and pathological groups, suggesting that different movement strategies may be represented. However, these studies have used discrete time point variables and usually focused on only one specific joint and plane of motion. Therefore, the first purpose of this study was to determine if running gait patterns for healthy subjects could be classified into homogeneous subgroups using three-dimensional kinematic data from the ankle, knee, and hip joints. The second purpose was to identify differences in joint kinematics between these groups. The third purpose was to investigate the practical implications of clustering healthy subjects by comparing these kinematics with runners experiencing patellofemoral pain (PFP). A principal component analysis (PCA) was used to reduce the dimensionality of the entire gait waveform data and then a hierarchical cluster analysis (HCA) determined group sets of similar gait patterns and homogeneous clusters. The results show two distinct running gait patterns were found with the main between-group differences occurring in frontal and sagittal plane knee angles (P<0.001), independent of age, height, weight, and running speed. When these two groups were compared to PFP runners, one cluster exhibited greater while the other exhibited reduced peak knee abduction angles (P<0.05). The variability observed in running patterns across this sample could be the result of different gait strategies. These results suggest care must be taken when selecting samples of subjects in order to investigate the pathomechanics of injured runners.

  5. Validity of the Kinect for Gait Assessment: A Focused Review

    PubMed Central

    Springer, Shmuel; Yogev Seligmann, Galit

    2016-01-01

    Gait analysis may enhance clinical practice. However, its use is limited due to the need for expensive equipment which is not always available in clinical settings. Recent evidence suggests that Microsoft Kinect may provide a low cost gait analysis method. The purpose of this report is to critically evaluate the literature describing the concurrent validity of using the Kinect as a gait analysis instrument. An online search of PubMed, CINAHL, and ProQuest databases was performed. Included were studies in which walking was assessed with the Kinect and another gold standard device, and consisted of at least one numerical finding of spatiotemporal or kinematic measures. Our search identified 366 papers, from which 12 relevant studies were retrieved. The results demonstrate that the Kinect is valid only for some spatiotemporal gait parameters. Although the kinematic parameters measured by the Kinect followed the trend of the joint trajectories, they showed poor validity and large errors. In conclusion, the Kinect may have the potential to be used as a tool for measuring spatiotemporal aspects of gait, yet standardized methods should be established, and future examinations with both healthy subjects and clinical participants are required in order to integrate the Kinect as a clinical gait analysis tool. PMID:26861323

  6. Gait Planning and Stability Control of a Quadruped Robot.

    PubMed

    Li, Junmin; Wang, Jinge; Yang, Simon X; Zhou, Kedong; Tang, Huijuan

    2016-01-01

    In order to realize smooth gait planning and stability control of a quadruped robot, a new controller algorithm based on CPG-ZMP (central pattern generator-zero moment point) is put forward in this paper. To generate smooth gait and shorten the adjusting time of the model oscillation system, a new CPG model controller and its gait switching strategy based on Wilson-Cowan model are presented in the paper. The control signals of knee-hip joints are obtained by the improved multi-DOF reduced order control theory. To realize stability control, the adaptive speed adjustment and gait switch are completed by the real-time computing of ZMP. Experiment results show that the quadruped robot's gaits are efficiently generated and the gait switch is smooth in the CPG control algorithm. Meanwhile, the stability of robot's movement is improved greatly with the CPG-ZMP algorithm. The algorithm in this paper has good practicability, which lays a foundation for the production of the robot prototype. PMID:27143959

  7. Two reciprocal translocations provide new clues to the high mutability of the Grid2 locus.

    PubMed

    Robinson, Kellie O; Petersen, Angela M; Morrison, Stephanie N; Elso, Colleen M; Stubbs, Lisa

    2005-01-01

    We describe two new mutations, 153Gso and 154Gso, associated with reciprocal translocations with a common breakpoint in mouse chromosome 6B3 (Mmu6B3). The translocations arose independently in offspring of male mice treated with chlorambucil and glycidamide, respectively. Homozygotes of both mutant stocks display a characteristic gait ataxia with 'foot-patting' behavior; despite their ataxia the mutant animals are healthy, long-lived, and breed normally. Breeding experiments confirmed that 153Gso and 154Gso mutations are allelic, and both fail to complement a known mutation hotfoot (ho), a Mmu6 mutation involving the glutamate receptor gene, Grid2, that is associated with a virtually identical phenotype. Our studies demonstrate that the 153Gso and 154Gso mutations disrupt the Grid2 gene at sites located more than 100 kb apart in intron 6 and intron 4 of the gene, respectively. The occurrence of two independent translocations from a relatively small colony within the same locus supports data suggesting the hypermutability of the Grid2 locus and suggest that the gene's large size make it an especially likely target for mutations involving genetic rearrangement.

  8. Similarity and Reciprocity in the Friendships of Elementary School Children.

    ERIC Educational Resources Information Center

    Clark, M. L.; Drewry, Debra L.

    1985-01-01

    Investigated the effect of similarity and reciprocity on dyadic friendship choices in third- and sixth-grade students. Reciprocal (mutual) friendships were more similar in proximity, popularity, and self-concept than those in nonreciprocal (nonmutual) dyads. Results are discussed in relation to the interpersonal attraction theories. (Author/DST)

  9. Structural Implications of Reciprocal Exchange: A Power-Dependence Approach

    ERIC Educational Resources Information Center

    Bonacich, Phillip; Bienenstock, Elisa Jayne

    2009-01-01

    This paper presents and tests a general model to predict emergent exchange patterns and power differences in reciprocal exchange networks when individual actors follow the norm of reciprocity. With an interesting qualification, the experimental results reported here support the power-dependence approach (Emerson 1972a, b): those who acquire the…

  10. Symmetry-based reciprocity: evolutionary constraints on a proximate mechanism

    PubMed Central

    Campennì, Marco

    2016-01-01

    Background. While the evolution of reciprocal cooperation has attracted an enormous attention, the proximate mechanisms underlying the ability of animals to cooperate reciprocally are comparatively neglected. Symmetry-based reciprocity is a hypothetical proximate mechanism that has been suggested to be widespread among cognitively unsophisticated animals. Methods. We developed two agent-based models of symmetry-based reciprocity (one relying on an arbitrary tag and the other on interindividual proximity) and tested their ability both to reproduce significant emergent features of cooperation in group living animals and to promote the evolution of cooperation. Results. Populations formed by agents adopting symmetry-based reciprocity showed differentiated “social relationships” and a positive correlation between cooperation given and received: two common aspects of animal cooperation. However, when reproduction and selection across multiple generations were added to the models, agents adopting symmetry-based reciprocity were outcompeted by selfish agents that never cooperated. Discussion. In order to evolve, hypothetical proximate mechanisms must be able to stand competition from alternative strategies. While the results of our simulations require confirmation using analytical methods, we provisionally suggest symmetry-based reciprocity is to be abandoned as a possible proximate mechanism underlying the ability of animals to reciprocate cooperative interactions. PMID:26998412

  11. Symmetry-based reciprocity: evolutionary constraints on a proximate mechanism.

    PubMed

    Campennì, Marco; Schino, Gabriele

    2016-01-01

    Background. While the evolution of reciprocal cooperation has attracted an enormous attention, the proximate mechanisms underlying the ability of animals to cooperate reciprocally are comparatively neglected. Symmetry-based reciprocity is a hypothetical proximate mechanism that has been suggested to be widespread among cognitively unsophisticated animals. Methods. We developed two agent-based models of symmetry-based reciprocity (one relying on an arbitrary tag and the other on interindividual proximity) and tested their ability both to reproduce significant emergent features of cooperation in group living animals and to promote the evolution of cooperation. Results. Populations formed by agents adopting symmetry-based reciprocity showed differentiated "social relationships" and a positive correlation between cooperation given and received: two common aspects of animal cooperation. However, when reproduction and selection across multiple generations were added to the models, agents adopting symmetry-based reciprocity were outcompeted by selfish agents that never cooperated. Discussion. In order to evolve, hypothetical proximate mechanisms must be able to stand competition from alternative strategies. While the results of our simulations require confirmation using analytical methods, we provisionally suggest symmetry-based reciprocity is to be abandoned as a possible proximate mechanism underlying the ability of animals to reciprocate cooperative interactions.

  12. Strong reciprocity is not uncommon in the "wild".

    PubMed

    Runciman, W G

    2012-02-01

    Guala is right to draw attention to the difficulty of extrapolating from the experimental evidence for weak or strong reciprocity to what is observed in the "wild." However, there may be more strong reciprocity in real-world communities than he allows for, as strikingly illustrated in the example of the Mafia.

  13. Proximate and ultimate causes of punishment and strong reciprocity.

    PubMed

    Barclay, Pat

    2012-02-01

    While admirable, Guala's discussion of reciprocity suffers from a confusion between proximate causes (psychological mechanisms triggering behaviour) and ultimate causes (evolved function of those psychological mechanisms). Because much work on "strong reciprocity" commits this error, I clarify the difference between proximate and ultimate causes of cooperation and punishment. I also caution against hasty rejections of "wide readings" of experimental evidence.

  14. 2005 Reciprocity Agreements and Other Student Exchange Options

    ERIC Educational Resources Information Center

    Washington Higher Education Coordinating Board, 2005

    2005-01-01

    The Higher Education Coordinating Board (HECB) is required by state law to report to the governor and legislature every two years on the status of Washington's state-level reciprocity agreements with Idaho, Oregon, and British Columbia. Reciprocity agreements allow some Washington students to attend public colleges in other states and pay lower…

  15. Instructional Guidance in Reciprocal Peer Tutoring With Task Cards

    ERIC Educational Resources Information Center

    Iserbyt, Peter; Elen, Jan; Behets, Daniel

    2010-01-01

    This article addresses the issue of instructional guidance in reciprocal peer tutoring with task cards as learning tools. Eighty-six Kinesiology students (age 17-19 years) were randomized across four reciprocal peer tutoring settings, differing in quality and quantity of guidance, to learn Basic Life Support (BLS) with task cards. The separate and…

  16. An Analysis of Direct Reciprocal Borrowing among Quebec University Libraries

    ERIC Educational Resources Information Center

    Duy, Joanna C.; Lariviere, Vincent

    2013-01-01

    An analysis of Quebec academic libraries' direct reciprocal borrowing statistics from 2005 to 2010 reveals that the physical distance separating universities plays an important role in determining the amount of direct reciprocal borrowing activity conducted between institutions. Significant statistical correlations were also seen between the…

  17. Using Excel's Matrix Operations to Facilitate Reciprocal Cost Allocations

    ERIC Educational Resources Information Center

    Leese, Wallace R.; Kizirian, Tim

    2009-01-01

    The reciprocal method of service department cost allocation requires linear equations to be solved simultaneously. These computations are often so complex as to cause the abandonment of the reciprocal method in favor of the less sophisticated direct or step-down methods. Here is a short example demonstrating how Excel's sometimes unknown matrix…

  18. Lack of Acceptance of Reciprocity Norms in Preschool Children.

    ERIC Educational Resources Information Center

    Berndt, Thomas J.

    1979-01-01

    Two studies investigated preschool children's acceptance of the reciprocity norms that allow retaliation and that require returning favors. Children viewed cartoons that portrayed animal puppets involved in reciprocal or nonreciprocal aggressive and prosocial behavior. They were then asked to evaluate the actor in each cartoon as "good" or "bad"…

  19. Reciprocal Mentorship: An Effective Support for Online Instructors

    ERIC Educational Resources Information Center

    Gabriel, Martha A.; Kaufield, Kandra J.

    2008-01-01

    This article presents a reciprocal model of mentoring as an alternative approach to more traditional mentoring models. A mentor, experienced with online course delivery and pedagogy, worked with six online instructors over two academic terms within a reciprocal mentorship model. This model was designed to build a collaborative learning…

  20. 47 CFR 51.711 - Symmetrical reciprocal compensation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 3 2012-10-01 2012-10-01 false Symmetrical reciprocal compensation. 51.711 Section 51.711 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES... Traffic § 51.711 Symmetrical reciprocal compensation. (a) Rates for transport and termination of...

  1. Reciprocal Relationships between Math Self-Concept and Math Anxiety

    ERIC Educational Resources Information Center

    Ahmed, Wondimu; Minnaert, Alexander; Kuyper, Hans; van der Werf, Greetje

    2012-01-01

    The present study examined the reciprocal relationships between self-concept and anxiety in mathematics. A sample of 495 grade 7 students (51% girls) completed self-report measures assessing self-concept and anxiety three times in a school year. Structural equation modeling was used to test a cross-lagged panel model of reciprocal effects between…

  2. Symmetry-based reciprocity: evolutionary constraints on a proximate mechanism.

    PubMed

    Campennì, Marco; Schino, Gabriele

    2016-01-01

    Background. While the evolution of reciprocal cooperation has attracted an enormous attention, the proximate mechanisms underlying the ability of animals to cooperate reciprocally are comparatively neglected. Symmetry-based reciprocity is a hypothetical proximate mechanism that has been suggested to be widespread among cognitively unsophisticated animals. Methods. We developed two agent-based models of symmetry-based reciprocity (one relying on an arbitrary tag and the other on interindividual proximity) and tested their ability both to reproduce significant emergent features of cooperation in group living animals and to promote the evolution of cooperation. Results. Populations formed by agents adopting symmetry-based reciprocity showed differentiated "social relationships" and a positive correlation between cooperation given and received: two common aspects of animal cooperation. However, when reproduction and selection across multiple generations were added to the models, agents adopting symmetry-based reciprocity were outcompeted by selfish agents that never cooperated. Discussion. In order to evolve, hypothetical proximate mechanisms must be able to stand competition from alternative strategies. While the results of our simulations require confirmation using analytical methods, we provisionally suggest symmetry-based reciprocity is to be abandoned as a possible proximate mechanism underlying the ability of animals to reciprocate cooperative interactions. PMID:26998412

  3. Transient nature of cooperation by pay-it-forward reciprocity

    PubMed Central

    Horita, Yutaka; Takezawa, Masanori; Kinjo, Takuji; Nakawake, Yo; Masuda, Naoki

    2016-01-01

    Humans often forward kindness received from others to strangers, a phenomenon called the upstream or pay-it-forward indirect reciprocity. Some field observations and laboratory experiments found evidence of pay-it-forward reciprocity in which chains of cooperative acts persist in social dilemma situations. Theoretically, however, cooperation based on pay-it-forward reciprocity is not sustainable. We carried out laboratory experiments of a pay-it-forward indirect reciprocity game (i.e., chained gift-giving game) on a large scale in terms of group size and time. We found that cooperation consistent with pay-it-forward reciprocity occurred only in a first few decisions per participant and that cooperation originated from inherent pro-sociality of individuals. In contrast, the same groups of participants showed persisting chains of cooperation in a different indirect reciprocity game in which participants earned reputation by cooperating. Our experimental results suggest that pay-it-forward reciprocity is transient and disappears when a person makes decisions repeatedly, whereas the reputation-based reciprocity is stable in the same situation. PMID:26786178

  4. Changes in the referent body location and configuration may underlie human gait, as confirmed by findings of multi-muscle activity minimizations and phase resetting.

    PubMed

    Feldman, Anatol G; Krasovsky, Tal; Baniña, Melanie C; Lamontagne, Anouk; Levin, Mindy F

    2011-04-01

    stability of posture and gait and advances the understanding of how human locomotion involves the whole body and is accomplished in a spatial frame of reference associated with the environment.

  5. The effect of the 'Gait keeper' mutation in the DMRT3 gene on gaiting ability in Icelandic horses.

    PubMed

    Kristjansson, T; Bjornsdottir, S; Sigurdsson, A; Andersson, L S; Lindgren, G; Helyar, S J; Klonowski, A M; Arnason, T

    2014-12-01

    A nonsense mutation in DMRT3 ('Gait keeper' mutation) has a predominant effect on gaiting ability in horses, being permissive for the ability to perform lateral gaits and having a favourable effect on speed capacity in trot. The DMRT3 mutant allele (A) has been found in high frequency in gaited breeds and breeds bred for harness racing, while other horse breeds were homozygous for the wild-type allele (C). The aim of this study was to evaluate further the effect of the DMRT3 nonsense mutation on the gait quality and speed capacity in the multigaited Icelandic horse and demonstrate how the frequencies of the A- and C- alleles have changed in the Icelandic horse population in recent decades. It was confirmed that homozygosity for the DMRT3 nonsense mutation relates to the ability to pace. It further had a favourable effect on scores in breeding field tests for the lateral gait tölt, demonstrated by better beat quality, speed capacity and suppleness. Horses with the CA genotype had on the other hand significantly higher scores for walk, trot, canter and gallop, and they performed better beat and suspension in trot and gallop. These results indicate that the AA genotype reinforces the coordination of ipsilateral legs, with the subsequent negative effect on the synchronized movement of diagonal legs compared with the CA genotype. The frequency of the A-allele has increased in recent decades with a corresponding decrease in the frequency of the C-allele. The estimated frequency of the A-allele in the Icelandic horse population in 2012 was 0.94. Selective breeding for lateral gaits in the Icelandic horse population has apparently altered the frequency of DMRT3 genotypes with a predicted loss of the C-allele in relatively few years. The results have practical implications for breeding and training of Icelandic horses and other gaited horse breeds.

  6. 76 FR 8661 - Airworthiness Directives; Lycoming Engines, Fuel Injected Reciprocating Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ...-14-07, Amendment 39-15602 (73 FR 39574), for certain fuel injected reciprocating engines manufactured... Directives; Lycoming Engines, Fuel Injected Reciprocating Engines AGENCY: Federal Aviation Administration... airworthiness directive (AD) that applies to certain fuel injected reciprocating engines manufactured...

  7. Does food sharing in vampire bats demonstrate reciprocity?

    PubMed

    Carter, Gerald; Wilkinson, Gerald

    2013-11-01

    Claims of reciprocity (or reciprocal altruism) in animal societies often ignite controversy because authors disagree over definitions, naturalistic studies tend to demonstrate correlation not causation, and controlled experiments often involve artificial conditions. Food sharing among common vampire bats has been a classic textbook example of reciprocity, but this conclusion has been contested by alternative explanations. Here, we review factors that predict food sharing in vampire bats based on previously published and unpublished data, validate previous published results with more precise relatedness estimates, and describe current evidence for and against alternative explanations for its evolutionary stability. Although correlational evidence indicates a role for both direct and indirect fitness benefits, unequivocally demonstrating reciprocity in vampire bats still requires testing if and how bats respond to non-reciprocation.

  8. Does food sharing in vampire bats demonstrate reciprocity?

    PubMed

    Carter, Gerald; Wilkinson, Gerald

    2013-11-01

    Claims of reciprocity (or reciprocal altruism) in animal societies often ignite controversy because authors disagree over definitions, naturalistic studies tend to demonstrate correlation not causation, and controlled experiments often involve artificial conditions. Food sharing among common vampire bats has been a classic textbook example of reciprocity, but this conclusion has been contested by alternative explanations. Here, we review factors that predict food sharing in vampire bats based on previously published and unpublished data, validate previous published results with more precise relatedness estimates, and describe current evidence for and against alternative explanations for its evolutionary stability. Although correlational evidence indicates a role for both direct and indirect fitness benefits, unequivocally demonstrating reciprocity in vampire bats still requires testing if and how bats respond to non-reciprocation. PMID:24505498

  9. Ultimate and proximate mechanisms of reciprocal altruism in rats.

    PubMed

    Dolivo, Vassilissa; Rutte, Claudia; Taborsky, Michael

    2016-09-01

    The reciprocal exchange of goods and services among social partners is a conundrum in evolutionary biology because of its proneness to cheating, but also the behavioral and cognitive mechanisms involved in such mutual cooperation are hotly debated. Extreme viewpoints range from the assumption that, at the proximate level, observed cases of "direct reciprocity" can be merely explained by basic instrumental and Pavlovian association processes, to the other extreme implying that "cultural factors" must be involved, as is often attributed to reciprocal cooperation among humans. Here we argue that neither one nor the other extreme conception is likely to explain proximate mechanisms underlying reciprocal altruism in animals. In particular, we outline that Pavlovian association processes are not sufficient to explain the documented reciprocal cooperation among Norway rats, as has been recently argued. PMID:27495930

  10. Reciprocal and unidirectional scattering of parity-time symmetric structures

    PubMed Central

    Jin, L.; Zhang, X. Z.; Zhang, G.; Song, Z.

    2016-01-01

    Parity-time symmetry is of great interest. The reciprocal and unidirectional features are intriguing besides the symmetry phase transition. Recently, the reciprocal transmission, unidirectional reflectionless and invisibility are intensively studied. Here, we show the reciprocal reflection/transmission in -symmetric system is closely related to the type of symmetry, that is, the axial (reflection) symmetry leads to reciprocal reflection (transmission). The results are further elucidated by studying the scattering of rhombic ring form coupled resonators with enclosed synthetic magnetic flux. The nonreciprocal phase shift induced by the magnetic flux and gain/loss break the parity and time-reversal symmetry but keep the parity-time symmetry. The reciprocal reflection (transmission) and unidirectional transmission (reflection) are found in the axial (reflection) -symmetric ring centre. The explorations of symmetry and asymmetry from symmetry may shed light on novel one-way optical devices and application of -symmetric metamaterials. PMID:26876806

  11. Permanent junctional reciprocating tachycardia in a dog.

    PubMed

    Santilli, Roberto A; Santos, Luis F N; Perego, Manuela

    2013-09-01

    A 5-year-old male English Bulldog was presented with a 1-year history of paroxysmal supraventricular tachycardia (SVT) partially responsive to amiodarone. At admission the surface ECG showed sustained runs of a narrow QRS complex tachycardia, with a ventricular cycle length (R-R interval) of 260 ms, alternating with periods of sinus rhythm. Endocardial mapping identified the electrogenic mechanism of the SVT as a circus movement tachycardia with retrograde and decremental conduction along a concealed postero-septal atrioventricular pathway (AP) and anterograde conduction along the atrioventricular node. These characteristics were indicative of a permanent junctional reciprocating tachycardia (PJRT). Radiofrequency catheter ablation of the AP successfully terminated the PJRT, with no recurrence of tachycardia on Holter monitoring at 12 months follow-up.

  12. Linkage map construction involving a reciprocal translocation.

    PubMed

    Farré, A; Benito, I Lacasa; Cistué, L; de Jong, J H; Romagosa, I; Jansen, J

    2011-03-01

    This paper is concerned with a novel statistical-genetic approach for the construction of linkage maps in populations obtained from reciprocal translocation heterozygotes of barley (Hordeum vulgare L.). Using standard linkage analysis, translocations usually lead to 'pseudo-linkage': the mixing up of markers from the chromosomes involved in the translocation into a single linkage group. Close to the translocation breakpoints recombination is severely suppressed and, as a consequence, ordering markers in those regions is not feasible. The novel strategy presented in this paper is based on (1) disentangling the "pseudo-linkage" using principal coordinate analysis, (2) separating individuals into translocated types and normal types and (3) separating markers into those close to and those more distant from the translocation breakpoints. The methods make use of a consensus map of the species involved. The final product consists of integrated linkage maps of the distal parts of the chromosomes involved in the translocation.

  13. Fluid flow within reciprocating-engine cylinders

    NASA Astrophysics Data System (ADS)

    Awn, A. G.; Spalding, D. B.

    The present investigation has the objective to demonstrate a method of predicting the flow within reciprocating-engine cylinders. The application of this approach can help the engine designer to increase the combustion efficiency and to reduce pollution. The considered method employs finite-difference equations similar to those used by Watkins (1973) and Chong et. al. (1976). The equations are, however, solved by a somewhat different method, and, in addition, an interface-tracking procedure is employed. The numerical procedure is further extended to investigate the scavenging flows in two-stroke engines. One problem studied in the investigation is concerned with the prediction of the velocity field in an engine cylinder during the harmonic motion of a flat-topped piston. A second problem involves the study of the flow behavior during the scavenging cycle in two-stroke engine cyclinders.

  14. Non-reciprocal ultrafast laser writing

    NASA Astrophysics Data System (ADS)

    Yang, Weijia; Kazansky, Peter G.; Svirko, Yuri P.

    2008-02-01

    Photosensitivity is a material property that is relevant to many phenomena and applications, from photosynthesis and photography to optical data storage and ultrafast laser writing. It was commonly thought that, in a homogeneous medium, photosensitivity and the corresponding light-induced material modifications do not change on reversing the direction of light propagation. Here we demonstrate that when the direction of the femtosecond laser beam is reversed from the +z to -z direction, the structures written in LiNbO3 crystal when translating the beam along the +y and -y directions are mirrored. In a non-centrosymmetric medium, modification of the material can therefore differ for light propagating in opposite directions. This is the first evidence of a new optical phenomenon of non-reciprocal photosensitivity. We interpret this effect in terms of light pressure and associated heat flow, resulting in a temperature gradient in homogeneous media without inversion symmetry under uniform intense irradiation.

  15. Balancing mechanism for reciprocating piston engine

    SciTech Connect

    Murata, N.; Ogino, T.

    1987-04-14

    This patent describes a balancing mechanism for a reciprocating piston internal combustion engine which includes a cylinder, a piston reciprocatable in the cylinder, a crankcase, a crankshaft mounted in the crankshaft, a crankpin connected to the piston, and a pair of crank arms bridging the crankshaft and crankpin. The crank arms and crankpin rotate with the crankshaft during operation and form a rotating mass. The balancing mechanism comprises at least one rotating counterweight attached to and rotating with the crankshaft, and eccentric journal means on the crankshaft adjacent the crank arms, rotating with the crankshaft. The journal means has an axis spaced to the side of the crankshaft axis which is opposite from the crankpin. The rotating counterweight and the eccentric journal means counterbalancing the rotating mass.

  16. Dynamic reciprocity in the wound microenvironment.

    PubMed

    Schultz, Gregory S; Davidson, Jeffrey M; Kirsner, Robert S; Bornstein, Paul; Herman, Ira M

    2011-01-01

    Here, we define dynamic reciprocity (DR) as an ongoing, bidirectional interaction among cells and their surrounding microenvironment. In this review, we posit that DR is especially meaningful during wound healing as the DR-driven biochemical, biophysical, and cellular responses to injury play pivotal roles in regulating tissue regenerative responses. Such cell-extracellular matrix interactions not only guide and regulate cellular morphology, but also cellular differentiation, migration, proliferation, and survival during tissue development, including, e.g., embryogenesis, angiogenesis, as well as during pathologic processes including cancer, diabetes, hypertension, and chronic wound healing. Herein, we examine DR within the wound microenvironment while considering specific examples across acute and chronic wound healing. This review also considers how a number of hypotheses that attempt to explain chronic wound pathophysiology may be understood within the DR framework. The implications of applying the principles of DR to optimize wound care practice and future development of innovative wound healing therapeutics are also briefly considered.

  17. Sleep and exercise: a reciprocal issue?

    PubMed

    Chennaoui, Mounir; Arnal, Pierrick J; Sauvet, Fabien; Léger, Damien

    2015-04-01

    Sleep and exercise influence each other through complex, bilateral interactions that involve multiple physiological and psychological pathways. Physical activity is usually considered as beneficial in aiding sleep although this link may be subject to multiple moderating factors such as sex, age, fitness level, sleep quality and the characteristics of the exercise (intensity, duration, time of day, environment). It is therefore vital to improve knowledge in fundamental physiology in order to understand the benefits of exercise on the quantity and quality of sleep in healthy subjects and patients. Conversely, sleep disturbances could also impair a person's cognitive performance or their capacity for exercise and increase the risk of exercise-induced injuries either during extreme and/or prolonged exercise or during team sports. This review aims to describe the reciprocal fundamental physiological effects linking sleep and exercise in order to improve the pertinent use of exercise in sleep medicine and prevent sleep disorders in sportsmen.

  18. Thermal Powered Reciprocating-Force Motor

    NASA Technical Reports Server (NTRS)

    Tatum, III, Paul F. (Inventor); McDow Elliott, Amelia (Inventor)

    2015-01-01

    A thermal-powered reciprocating-force motor includes a shutter switchable between a first position that passes solar energy and a second position that blocks solar energy. A shape memory alloy (SMA) actuator is coupled to the shutter to control switching thereof between the shutter's first and second position. The actuator is positioned with respect to the shutter such that (1) solar energy impinges on the SMA when the shutter is in its first position so that the SMA experiences contraction in length until the shutter is switched to its second position, and (2) solar energy is impeded from impingement on the SMA when the shutter is in its second position so that the SMA experiences extension in length. Elastic members coupled to the actuator apply a force to the SMA that aids in its extension in length until the shutter is switched to its first position.

  19. Extraction of human gait signatures: an inverse kinematic approach using Groebner basis theory applied to gait cycle analysis

    NASA Astrophysics Data System (ADS)

    Barki, Anum; Kendricks, Kimberly; Tuttle, Ronald F.; Bunker, David J.; Borel, Christoph C.

    2013-05-01

    This research highlights the results obtained from applying the method of inverse kinematics, using Groebner basis theory, to the human gait cycle to extract and identify lower extremity gait signatures. The increased threat from suicide bombers and the force protection issues of today have motivated a team at Air Force Institute of Technology (AFIT) to research pattern recognition in the human gait cycle. The purpose of this research is to identify gait signatures of human subjects and distinguish between subjects carrying a load to those subjects without a load. These signatures were investigated via a model of the lower extremities based on motion capture observations, in particular, foot placement and the joint angles for subjects affected by carrying extra load on the body. The human gait cycle was captured and analyzed using a developed toolkit consisting of an inverse kinematic motion model of the lower extremity and a graphical user interface. Hip, knee, and ankle angles were analyzed to identify gait angle variance and range of motion. Female subjects exhibited the most knee angle variance and produced a proportional correlation between knee flexion and load carriage.

  20. The efficient interaction of indirect reciprocity and costly punishment.

    PubMed

    Rockenbach, Bettina; Milinski, Manfred

    2006-12-01

    Human cooperation in social dilemmas challenges researchers from various disciplines. Here we combine advances in experimental economics and evolutionary biology that separately have shown that costly punishment and reputation formation, respectively, induce cooperation in social dilemmas. The mechanisms of punishment and reputation, however, substantially differ in their means for 'disciplining' non-cooperators. Direct punishment incurs salient costs for both the punisher and the punished, whereas reputation mechanisms discipline by withholding action, immediately saving costs for the 'punisher'. Consequently, costly punishment may become extinct in environments in which effective reputation building--for example, through indirect reciprocity--provides a cheaper and powerful way to sustain cooperation. Unexpectedly, as we show here, punishment is maintained when a combination with reputation building is available, however, at a low level. Costly punishment acts are markedly reduced although not simply substituted by appreciating reputation. Indeed, the remaining punishment acts are concentrated on free-riders, who are most severely punished in the combination. When given a choice, subjects even prefer a combination of reputation building with costly punishment. The interaction between punishment and reputation building boosts cooperative efficiency. Because punishment and reputation building are omnipresent interacting forces in human societies, costly punishing should appear less destructive without losing its deterring force. PMID:17151660

  1. The efficient interaction of indirect reciprocity and costly punishment.

    PubMed

    Rockenbach, Bettina; Milinski, Manfred

    2006-12-01

    Human cooperation in social dilemmas challenges researchers from various disciplines. Here we combine advances in experimental economics and evolutionary biology that separately have shown that costly punishment and reputation formation, respectively, induce cooperation in social dilemmas. The mechanisms of punishment and reputation, however, substantially differ in their means for 'disciplining' non-cooperators. Direct punishment incurs salient costs for both the punisher and the punished, whereas reputation mechanisms discipline by withholding action, immediately saving costs for the 'punisher'. Consequently, costly punishment may become extinct in environments in which effective reputation building--for example, through indirect reciprocity--provides a cheaper and powerful way to sustain cooperation. Unexpectedly, as we show here, punishment is maintained when a combination with reputation building is available, however, at a low level. Costly punishment acts are markedly reduced although not simply substituted by appreciating reputation. Indeed, the remaining punishment acts are concentrated on free-riders, who are most severely punished in the combination. When given a choice, subjects even prefer a combination of reputation building with costly punishment. The interaction between punishment and reputation building boosts cooperative efficiency. Because punishment and reputation building are omnipresent interacting forces in human societies, costly punishing should appear less destructive without losing its deterring force.

  2. Effects of Aging on Arm Swing during Gait: The Role of Gait Speed and Dual Tasking

    PubMed Central

    Mirelman, Anat; Bernad-Elazari, Hagar; Nobel, Tomer; Thaler, Avner; Peruzzi, Agnese; Plotnik, Meir; Giladi, Nir; Hausdorff, Jeffrey M.

    2015-01-01

    Healthy walking is characterized by pronounced arm swing and axial rotation. Aging effects on gait speed, stride length and stride time variability have been previously reported, however, less is known about aging effects on arm swing and axial rotation and their relationship to age-associated gait changes during usual walking and during more challenging conditions like dual tasking. Sixty healthy adults between the ages of 30–77 were included in this study designed to address this gap. Lightweight body fixed sensors were placed on each wrist and lower back. Participants walked under 3 walking conditions each of 1 minute: 1) comfortable speed, 2) walking while serially subtracting 3’s (Dual Task), 3) walking at fast speed. Aging effects on arm swing amplitude, range, symmetry, jerk and axial rotation amplitude and jerk were compared between decades of age (30–40; 41–50; 51–60; 61–77 years). As expected, older adults walked slower (p = 0.03) and with increased stride variability (p = 0.02). Arm swing amplitude decreased with age under all conditions (p = 0.04). In the oldest group, arm swing decreased during dual task and increased during the fast walking condition (p<0.0001). Similarly, arm swing asymmetry increased during the dual task in the older groups (p<0.004), but not in the younger groups (p = 0.67). Significant differences between groups and within conditions were observed in arm swing jerk (p<0.02), axial rotation amplitude (p<0.02) and axial jerk (p<0.001). Gait speed, arm swing amplitude of the dominant arm, arm swing asymmetry and axial rotation jerk were all independent predictors of age in a multivariate model. These findings suggest that the effects of gait speed and dual tasking on arm swing and axial rotation during walking are altered among healthy older adults. Follow-up work is needed to examine if these effects contribute to reduced stability in aging. PMID:26305896

  3. The mental representation of the human gait in young and older adults

    PubMed Central

    Stöckel, Tino; Jacksteit, Robert; Behrens, Martin; Skripitz, Ralf; Bader, Rainer; Mau-Moeller, Anett

    2015-01-01

    The link between mental representation (MREP) structures and motor performance has been evidenced for a great variety of movement skills, but not for the human gait. Therefore the present study sought to investigate the cognitive memory structures underlying the human gait in young and older adults. In a first experiment, gait parameters at comfortable gait speed (OptoGait) were compared with gait-specific MREPs (structural dimensional analysis of MREP; SDA-M) in 36 young adults. Participants were divided into a slow- and fast-walking group. The proven relationship between gait speed and executive functions such as working memory led to the hypothesis that gait pattern and MREP differ between slow- and fast-walking adults. In a second experiment, gait performance and MREPs were compared between 24 young (27.9 years) and 24 elderly (60.1 years) participants. As age-related declines in gait performance occur from the seventh decade of life onward, we hypothesized that gait parameters would not be affected until the age of 60 years accompanied by unchanged MREP. Data of experiment one revealed that gait parameters and MREPs differed significantly between slow and fast walkers. Notably, eleven previously incurred musculoskeletal injuries were documented for the slow walkers but only two injuries and one disorder for fast walkers. Experiment two revealed no age-related differences in gait parameters or MREPs between healthy young and older adults. In conclusion, the differences in gait parameters associated with lower comfortable gait speeds are reflected by differences in MREPs, whereby SDA-M data indicate that the single limb support phase may serve as a critical functional period. These differences probably resulted from previously incurred musculoskeletal injuries. Our data further indicate that the human gait and its MREP are stable until the age of 60. SDA-M may be considered as a valuable clinical tool for diagnosis of gait abnormalities and monitoring of

  4. Mechanical and neuromuscular changes with lateral trunk lean gait modifications.

    PubMed

    Robbins, Shawn M; Teoli, Anthony; Preuss, Richard A

    2016-09-01

    Lateral trunk lean (LTL) is a proposed intervention for knee osteoarthritis but increased muscular demands have not been considered. The objective was to compare lower extremity and trunk muscle activation and joint mechanics between normal and increased LTL gait in healthy adults. Participants (n=20, mean age 22 years) were examined under two gait conditions: normal and increased LTL. A motion capture system and force plates sampled at 100 and 2000Hz respectively were used to determine joint angles and external moments including LTL angle and external knee adduction moment (KAM). Surface electromyography, sampled at 2000Hz, measured activation of six trunk/hip muscles bilaterally. Peak LTL angle, peak KAM, gait speed, and mean values from electromyography waveforms were compared between normal and LTL conditions using paired t-tests or 2-way analysis of variance. There was a significant (p<0.05) increase in peak LTL angle, decrease in first but not second peak KAM, and decrease in gait speed during LTL gait. There were significant (p<0.01) increases in external oblique and iliocostalis muscle activation during LTL gait. There was no change in activation for internal oblique, rectus abdominis, longissimus, and gluteus medius. LTL gait decreased early/mid-stance KAM demonstrating its ability to decrease medial compartment knee loading. Increases in external oblique and iliocostalis activation were present but small to moderate in size and unlikely to lead to short term injury. Longitudinal studies should evaluate the effectiveness of increased LTL for knee osteoarthritis and if the increase in muscular demands leads to negative long term side effects.

  5. Gait control and executive dysfunction in early schizophrenia.

    PubMed

    Lallart, Elise; Jouvent, Roland; Herrmann, François R; Perez-Diaz, Fernando; Lallart, Xavier; Beauchet, Olivier; Allali, Gilles

    2014-04-01

    Dysexecutive functioning, which is described as an enduring core feature of schizophrenia, has been associated with gait disorders. However, few studies have reported gait disorders in schizophrenia patients. The objective of this study was to examine the association between executive dysfunction and gait performance in recent-onset schizophrenia patients using the dual task paradigm. Thirty-two subjects participated to the study: 17 with recent-onset schizophrenia and 15 healthy age-matched controls. Executive functions were evaluated using the Frontal Assessment Battery, Stroop and Trail-Making tests. Mean values and coefficients of variation (CV) of the temporal gait parameters while single tasking (just walking) and while dual tasking (walking and forward counting, walking and backward counting, walking and verbal fluency) were measured using the SMTEC(®)-footswitch system. We focused on the CV of stride time as this measure has been shown to be the most representative parameter of higher gait control. A strong effect of the stride time was found in the group factor for the verbal fluency dual-task when compared to controls (Cohen's d mean = 1.28 and CV = 1.05). The effect was lower in the other dual tasks, and insignificant in the single task of walking. This study shows that patients exhibit higher stride-to-stride variability while dual tasking than controls. It also shows a stronger impact of verbal fluency on gait regularity compared to the other dual tasks revealing a relationship between the executive dysfunction and gait modification. Those results are in line with the idea that schizophrenia implies not only cognitive but also motor functioning and coordination impairment. PMID:24201834

  6. General tensor discriminant analysis and gabor features for gait recognition.

    PubMed

    Tao, Dacheng; Li, Xuelong; Wu, Xindong; Maybank, Stephen J

    2007-10-01

    The traditional image representations are not suited to conventional classification methods, such as the linear discriminant analysis (LDA), because of the under sample problem (USP): the dimensionality of the feature space is much higher than the number of training samples. Motivated by the successes of the two dimensional LDA (2DLDA) for face recognition, we develop a general tensor discriminant analysis (GTDA) as a preprocessing step for LDA. The benefits of GTDA compared with existing preprocessing methods, e.g., principal component analysis (PCA) and 2DLDA, include 1) the USP is reduced in subsequent classification by, for example, LDA; 2) the discriminative information in the training tensors is preserved; and 3) GTDA provides stable recognition rates because the alternating projection optimization algorithm to obtain a solution of GTDA converges, while that of 2DLDA does not. We use human gait recognition to validate the proposed GTDA. The averaged gait images are utilized for gait representation. Given the popularity of Gabor function based image decompositions for image understanding and object recognition, we develop three different Gabor function based image representations: 1) the GaborD representation is the sum of Gabor filter responses over directions, 2) GaborS is the sum of Gabor filter responses over scales, and 3) GaborSD is the sum of Gabor filter responses over scales and directions. The GaborD, GaborS and GaborSD representations are applied to the problem of recognizing people from their averaged gait images.A large number of experiments were carried out to evaluate the effectiveness (recognition rate) of gait recognition based on first obtaining a Gabor, GaborD, GaborS or GaborSD image representation, then using GDTA to extract features and finally using LDA for classification. The proposed methods achieved good performance for gait recognition based on image sequences from the USF HumanID Database. Experimental comparisons are made with nine

  7. Meaningful Improvement in Gait Speed in Hip Fracture Recovery

    PubMed Central

    Alley, Dawn E.; Hicks, Gregory E.; Shardell, Michelle; Hawkes, William; Miller, Ram; Craik, Rebecca L.; Mangione, Kathleen K.; Orwig, Denise; Hochberg, Marc; Resnick, Barbara; Magaziner, Jay

    2011-01-01

    OBJECTIVES To estimate meaningful improvements in gait speed observed during recovery from hip fracture and to evaluate the sensitivity and specificity of gait speed changes in detecting change in self-reported mobility. DESIGN Secondary longitudinal data analysis from two randomized controlled trials SETTING Twelve hospitals in the Baltimore, Maryland, area. PARTICIPANTS Two hundred seventeen women admitted with hip fracture. MEASUREMENTS Usual gait speed and self-reported mobility (ability to walk 1 block and climb 1 flight of stairs) measured 2 and 12 months after fracture. RESULTS Effect size–based estimates of meaningful differences were 0.03 for small differences and 0.09 for substantial differences. Depending on the anchor (stairs vs walking) and method (mean difference vs regression), anchor-based estimates ranged from 0.10 to 0.17 m/s for small meaningful improvements and 0.17 to 0.26 m/s for substantial meaningful improvement. Optimal gait speed cut-points yielded low sensitivity (0.39–0.62) and specificity (0.57–0.76) for improvements in self-reported mobility. CONCLUSION Results from this sample of women recovering from hip fracture provide only limited support for the 0.10-m/s cut point for substantial meaningful change previously identified in community-dwelling older adults experiencing declines in walking abilities. Anchor-based estimates and cut points derived from receiver operating characteristic curve analysis suggest that greater improvements in gait speed may be required for substantial perceived mobility improvement in female hip fracture patients. Furthermore, gait speed change performed poorly in discriminating change in self-reported mobility. Estimates of meaningful change in gait speed may differ based on the direction of change (improvement vs decline) or between patient populations. PMID:21883109

  8. Do the chaotic features of gait change in Parkinson's disease?

    PubMed

    Sarbaz, Yashar; Towhidkhah, Farzad; Jafari, Ayyoob; Gharibzadeh, Shahriar

    2012-08-21

    Some previous studies have focused on chaotic properties of Parkinson's disease (PD). It seems that considering PD from dynamical systems perspective is a relevant method that may lead to better understanding of the disease. There is some ambiguity about chaotic nature in PD symptoms and normal behaviour. Some studies claim that normal gait has somehow a chaotic behaviour and disturbed gait in PD has decreased chaotic nature. However, it is worth noting that the basis of this idea is the difference of fractal behaviour in gait of normal and PD patients, which is concluded from Long Range Correlation (LRC) indices. Our primary calculations show that a large number of normal persons and patients have similar LRC. It seems that chaotic studies on PD need a different view. Because of short time recording of symptoms, accurate calculation of chaotic features is tough. On the other hand, long time recording of symptoms is experimentally difficult. In this research, we have first designed a physiologically plausible model for normal and PD gait. Then, after validating the model with neural network classifier, we used the model for extracting long time simulation of stride in normal and PD persons. These long time simulations were then used for calculating the chaotic features of gait. According to change of phase space behaviour and alteration of three largest lyapunov exponents, it was observed that simulated normal persons act as chaotic systems in stride production, but simulated PD does not have chaotic dynamics and is stochastic. Based on our results, it may be claimed that normal gait has chaotic nature which is disturbed in PD state. Surely, long time real recordings from gait signal in normal persons and PD patients are necessary to warranty this hypothesis.

  9. Massive weight loss-induced mechanical plasticity in obese gait.

    PubMed

    Hortobágyi, Tibor; Herring, Cortney; Pories, Walter J; Rider, Patrick; Devita, Paul

    2011-11-01

    We examined the hypothesis that metabolic surgery-induced massive weight loss causes mass-driven and behavioral adaptations in the kinematics and kinetics of obese gait. Gait analyses were performed at three time points over ∼1 yr in initially morbidly obese (mass: 125.7 kg; body mass index: 43.2 kg/m(2)) but otherwise healthy adults. Ten obese adults lost 27.1% ± 5.1 (34.0 ± 9.4 kg) weight by the first follow-up at 7.0 mo (±0.7) and 6.5 ± 4.2% (8.2 ± 6.0 kg) more by the second follow-up at 12.8 mo (±0.9), with a total weight loss of 33.6 ± 8.1% (42.2 ± 14.1 kg; P = 0.001). Subjects walked at a self-selected and a standard 1.5 m/s speed at the three time points and were also compared with an age- and gender-matched comparison group at the second follow-up. Weight loss increased swing time, stride length, gait speed, hip range of motion, maximal knee flexion, and ankle plantarflexion. Weight loss of 27% led to 3.9% increase in gait speed. An additional 6.5% weight loss led to an additional 7.3% increase in gait speed. Sagittal plane normalized knee torque increased and absolute ankle and frontal plane knee torques decreased after weight loss. We conclude that large weight loss produced mechanical plasticity by modifying ankle and knee torques and gait behavior. There may be a weight loss threshold of 30 kg limiting changes in gait kinematics. Implications for exercise prescription are also discussed.

  10. General tensor discriminant analysis and gabor features for gait recognition.

    PubMed

    Tao, Dacheng; Li, Xuelong; Wu, Xindong; Maybank, Stephen J

    2007-10-01

    The traditional image representations are not suited to conventional classification methods, such as the linear discriminant analysis (LDA), because of the under sample problem (USP): the dimensionality of the feature space is much higher than the number of training samples. Motivated by the successes of the two dimensional LDA (2DLDA) for face recognition, we develop a general tensor discriminant analysis (GTDA) as a preprocessing step for LDA. The benefits of GTDA compared with existing preprocessing methods, e.g., principal component analysis (PCA) and 2DLDA, include 1) the USP is reduced in subsequent classification by, for example, LDA; 2) the discriminative information in the training tensors is preserved; and 3) GTDA provides stable recognition rates because the alternating projection optimization algorithm to obtain a solution of GTDA converges, while that of 2DLDA does not. We use human gait recognition to validate the proposed GTDA. The averaged gait images are utilized for gait representation. Given the popularity of Gabor function based image decompositions for image understanding and object recognition, we develop three different Gabor function based image representations: 1) the GaborD representation is the sum of Gabor filter responses over directions, 2) GaborS is the sum of Gabor filter responses over scales, and 3) GaborSD is the sum of Gabor filter responses over scales and directions. The GaborD, GaborS and GaborSD representations are applied to the problem of recognizing people from their averaged gait images.A large number of experiments were carried out to evaluate the effectiveness (recognition rate) of gait recognition based on first obtaining a Gabor, GaborD, GaborS or GaborSD image representation, then using GDTA to extract features and finally using LDA for classification. The proposed methods achieved good performance for gait recognition based on image sequences from the USF HumanID Database. Experimental comparisons are made with nine

  11. Reciprocal Markov modeling of feedback mechanisms between emotion and dietary choice using experience sampling data

    PubMed Central

    Lu, Ji; Pan, Junhao; Zhang, Qiang; Dubé, Laurette; Ip, Edward H.

    2015-01-01

    With intensively collected longitudinal data, recent advances in Experience Sampling Method (ESM) benefit social science empirical research, but also pose important methodological challenges. As traditional statistical models are not generally well-equipped to analyze a system of variables that contain feedback loops, this paper proposes the utility of an extended hidden Markov model to model reciprocal relationship between momentary emotion and eating behavior. This paper revisited an ESM data set (Lu, Huet & Dube, 2011) that observed 160 participants’ food consumption and momentary emotions six times per day in 10 days. Focusing on the analyses on feedback loop between mood and meal healthiness decision, the proposed Reciprocal Markov Model (RMM) can accommodate both hidden (“general” emotional states: positive vs. negative state) and observed states (meal: healthier, same or less healthy than usual) without presuming independence between observations and smooth trajectories of mood or behavior changes. The results of RMM analyses illustrated the reciprocal chains of meal consumption and mood as well as the effect of contextual factors that moderate the interrelationship between eating and emotion. A simulation experiment that generated data consistent to the empirical study further demonstrated that the procedure is promising in terms of recovering the parameters. PMID:26717120

  12. Reciprocal insights into adaptation from agricultural and evolutionary studies in tomato

    PubMed Central

    Moyle, Leonie C; Muir, Christopher D

    2010-01-01

    Although traditionally separated by different aims and methodologies, research on agricultural and evolutionary problems shares a common goal of understanding the mechanisms underlying functionally important traits. As such, research in both fields offers potential complementary and reciprocal insights. Here, we discuss adaptive stress responses (specifically to water stress) as an example of potentially fruitful research reciprocity, where agricultural research has clearly produced advances that could benefit evolutionary studies, while evolutionary studies offer approaches and insights underexplored in crop studies. We focus on research on Solanum species that include the domesticated tomato and its wild relatives. Integrated approaches to understanding ecological adaptation are particularly attractive in tomato and its wild relatives: many presumptively adaptive phenotypic differences characterize wild species, and the physiological and mechanistic basis of many relevant traits and environmental responses has already been examined in the context of cultivated tomato and some wild species. We highlight four specific instances where these reciprocal insights can be combined to better address questions that are fundamental both to agriculture and evolution. PMID:25567935

  13. Apical Extrusion of Debris Produced during Continuous Rotating and Reciprocating Motion

    PubMed Central

    Nevares, Giselle; Xavier, Felipe; Gominho, Luciana; Cavalcanti, Flávia; Cassimiro, Marcely; Romeiro, Kaline; Alvares, Pamella; Queiroz, Gabriela; Sobral, Ana Paula; Gerbi, Marleny; Silveira, Marcia; Albuquerque, Diana

    2015-01-01

    This study aimed to analyse and compare apical extrusion of debris in canals instrumented with systems used in reciprocating and continuous motion. Sixty mandibular premolars were randomly divided into 3 groups (n = 20): the Reciproc (REC), WaveOne (WO), and HyFlex CM (HYF) groups. One Eppendorf tube per tooth was weighed in advance on an analytical balance. The root canals were instrumented according to the manufacturer's instructions, and standardised irrigation with 2.5% sodium hypochlorite was performed to a total volume of 9 mL. After instrumentation, the teeth were removed from the Eppendorf tubes and incubated at 37°C for 15 days to evaporate the liquid. The tubes were weighed again, and the difference between the initial and final weight was calculated to determine the weight of the debris. The data were statistically analysed using the Shapiro-Wilk, Wilcoxon, and Mann-Whitney tests (α = 5%). All systems resulted in the apical extrusion of debris. Reciproc produced significantly more debris than WaveOne (p < 0.05), and both systems produced a greater apical extrusion of debris than HyFlex CM (p < 0.001). Cross section and motion influenced the results, despite tip standardization. PMID:26543896

  14. Assessment of gait kinetics using triaxial accelerometers.

    PubMed

    Fortune, Emma; Morrow, Melissa M; Kaufman, Kenton R

    2014-10-01

    Repeated durations of dynamic activity with high ground reaction forces (GRFs) and loading rates (LRs) can be beneficial to bone health. To fully characterize dynamic activity in relation to bone health, field-based measurements of gait kinetics are desirable to assess free-living lower-extremity loading. The study aims were to determine correlations of peak vertical GRF and peak vertical LR with ankle peak vertical accelerations, and of peak resultant GRF and peak resultant LR with ankle peak resultant accelerations, and to compare them to correlations with tibia, thigh, and waist accelerations. GRF data were collected as ten healthy subjects (26 [19-34] years) performed 8-10 walking trials at velocities ranging from 0.19 to 3.05 m/s while wearing ankle, tibia, thigh, and waist accelerometers. While peak vertical accelerations of all locations were positively correlated with peak vertical GRF and LR (r² > .53, P < .001), ankle peak vertical accelerations were the most correlated (r² > .75, P < .001). All peak resultant accelerations were positively correlated with peak resultant GRF and LR (r² > .57, P < .001), with waist peak resultant acceleration being the most correlated (r² > .70, P < .001). The results suggest that ankle or waist accelerometers give the most accurate peak GRF and LR estimates and could be useful tools in relating physical activity to bone health.

  15. Quantification of gait in dystonic Gunn rats.

    PubMed

    Chaniary, Kunal D; Baron, Mark S; Rice, Ann C; Wetzel, Paul A; Ramakrishnan, Viswanathan; Shapiro, Steven M

    2009-06-15

    Spontaneously jaundiced Gunn rats exposed to sulfadimethoxine develop bilirubin encephalopathy (kernicterus) with hearing loss and dystonia, closely resembling the human syndrome. We recently characterized the electromyographic activity in this animal model supporting our clinical impression of dystonia. The objective of this study was to develop a simple, non-invasive method to quantify the motor deficits in dystonic rodents. On postnatal day 16, Gunn rats were treated with 100mg/kg of sulfadimethoxine or saline. On postnatal day 31, the ventral view of the animals was videotaped while the animals walked inside a Plexiglas chamber. Individual video frames were reviewed and specific gait parameters including hindlimb spread, step length ratio variability, stance/swing ratio and walking speed were compared between dystonic and non-dystonic jaundiced and non-jaundiced littermates. Data analysis demonstrated statistically significant increases in hindlimb spread and step length ratio variability and decreases in walking speed in dystonic animals as compared to controls. This study demonstrates a valuable technique to objectively characterize dystonia in Gunn rats, which could have wide use for other experimental movement disorders as well. PMID:19464517

  16. Assessment of gait kinetics using triaxial accelerometers.

    PubMed

    Fortune, Emma; Morrow, Melissa M; Kaufman, Kenton R

    2014-10-01

    Repeated durations of dynamic activity with high ground reaction forces (GRFs) and loading rates (LRs) can be beneficial to bone health. To fully characterize dynamic activity in relation to bone health, field-based measurements of gait kinetics are desirable to assess free-living lower-extremity loading. The study aims were to determine correlations of peak vertical GRF and peak vertical LR with ankle peak vertical accelerations, and of peak resultant GRF and peak resultant LR with ankle peak resultant accelerations, and to compare them to correlations with tibia, thigh, and waist accelerations. GRF data were collected as ten healthy subjects (26 [19-34] years) performed 8-10 walking trials at velocities ranging from 0.19 to 3.05 m/s while wearing ankle, tibia, thigh, and waist accelerometers. While peak vertical accelerations of all locations were positively correlated with peak vertical GRF and LR (r² > .53, P < .001), ankle peak vertical accelerations were the most correlated (r² > .75, P < .001). All peak resultant accelerations were positively correlated with peak resultant GRF and LR (r² > .57, P < .001), with waist peak resultant acceleration being the most correlated (r² > .70, P < .001). The results suggest that ankle or waist accelerometers give the most accurate peak GRF and LR estimates and could be useful tools in relating physical activity to bone health. PMID:25010675

  17. Gait Alterations During Constant Pace Treadmill Racewalking.

    PubMed

    Hanley, Brian

    2015-08-01

    Racewalking is an Olympic event requiring great endurance, and racewalkers often use treadmills in training because of the benefits of having a flat unchanging surface where pace judgment can be learned and because inclement weather can be avoided. The effects of fatigue associated with racewalking on a treadmill have not been studied and could be informative with regard to the maintenance of legal technique. The aim of this study was to measure key gait variables during a physically demanding treadmill racewalk. Fourteen international racewalkers completed 10 km on an instrumented treadmill at a pace equivalent to 103% of their recent best time. Spatiotemporal and ground reaction force data were recorded at 4 distances. High-speed videography data were simultaneously recorded to analyze changes in knee angle between the early and late stages. Increases in step length and corresponding decreases in cadence were found, although the small changes were not considered meaningful. There was also a small increase in flight time and a small decrease in push-off force. There were no other significant changes for any other variables (including knee angles). The increase in flight time might be important given that racewalkers are not permitted a visible loss of contact and suggests that fatiguing sessions on a treadmill can lead to the adoption of nonlegal technique. However, this disadvantage of treadmill training can be negated if the coach scrutinizes athletes throughout the session, and overall the consistent technique used is of benefit with regard to learning correct form and pacing ability. PMID:25647657

  18. Clustering in large networks does not promote upstream reciprocity.

    PubMed

    Masuda, Naoki

    2011-01-01

    Upstream reciprocity (also called generalized reciprocity) is a putative mechanism for cooperation in social dilemma situations with which players help others when they are helped by somebody else. It is a type of indirect reciprocity. Although upstream reciprocity is often observed in experiments, most theories suggest that it is operative only when players form short cycles such as triangles, implying a small population size, or when it is combined with other mechanisms that promote cooperation on their own. An expectation is that real social networks, which are known to be full of triangles and other short cycles, may accommodate upstream reciprocity. In this study, I extend the upstream reciprocity game proposed for a directed cycle by Boyd and Richerson to the case of general networks. The model is not evolutionary and concerns the conditions under which the unanimity of cooperative players is a Nash equilibrium. I show that an abundance of triangles or other short cycles in a network does little to promote upstream reciprocity. Cooperation is less likely for a larger population size even if triangles are abundant in the network. In addition, in contrast to the results for evolutionary social dilemma games on networks, scale-free networks lead to less cooperation than networks with a homogeneous degree distribution.

  19. The evolution of generalized reciprocity on social interaction networks.

    PubMed

    van Doorn, Gerrit Sander; Taborsky, Michael

    2012-03-01

    Generalized reciprocity (help anyone, if helped by someone) is a minimal strategy capable of supporting cooperation between unrelated individuals. Its simplicity makes it an attractive model to explain the evolution of reciprocal altruism in animals that lack the information or cognitive skills needed for other types of reciprocity. Yet, generalized reciprocity is anonymous and thus defenseless against exploitation by defectors. Recognizing that animals hardly ever interact randomly, we investigate whether social network structure can mitigate this vulnerability. Our results show that heterogeneous interaction patterns strongly support the evolution of generalized reciprocity. The future probability of being rewarded for an altruistic act is inversely proportional to the average connectivity of the social network when cooperators are rare. Accordingly, sparse networks are conducive to the invasion of reciprocal altruism. Moreover, the evolutionary stability of cooperation is enhanced by a modular network structure. Communities of reciprocal altruists are protected against exploitation, because modularity increases the mean access time, that is, the average number of steps that it takes for a random walk on the network to reach a defector. Sparseness and community structure are characteristic properties of vertebrate social interaction patterns, as illustrated by network data from natural populations ranging from fish to primates.

  20. Near optimal graphene terahertz non-reciprocal isolator.

    PubMed

    Tamagnone, Michele; Moldovan, Clara; Poumirol, Jean-Marie; Kuzmenko, Alexey B; Ionescu, Adrian M; Mosig, Juan R; Perruisseau-Carrier, Julien

    2016-04-06

    Isolators, or optical diodes, are devices enabling unidirectional light propagation by using non-reciprocal optical materials, namely materials able to break Lorentz reciprocity. The realization of isolators at terahertz frequencies is a very important open challenge made difficult by the intrinsically lossy propagation of terahertz radiation in current non-reciprocal materials. Here we report the design, fabrication and measurement of a terahertz non-reciprocal isolator for circularly polarized waves based on magnetostatically biased monolayer graphene, operating in reflection. The device exploits the non-reciprocal optical conductivity of graphene and, in spite of its simple design, it exhibits almost 20 dB of isolation and only 7.5 dB of insertion loss at 2.9 THz. Operation with linearly polarized light can be achieved using quarter-wave plates as polarization converters. These results demonstrate the superiority of graphene with respect to currently used terahertz non-reciprocal materials and pave the way to a novel class of optimal non-reciprocal devices.

  1. Near optimal graphene terahertz non-reciprocal isolator

    PubMed Central

    Tamagnone, Michele; Moldovan, Clara; Poumirol, Jean-Marie; Kuzmenko, Alexey B.; Ionescu, Adrian M.; Mosig, Juan R.; Perruisseau-Carrier, Julien

    2016-01-01

    Isolators, or optical diodes, are devices enabling unidirectional light propagation by using non-reciprocal optical materials, namely materials able to break Lorentz reciprocity. The realization of isolators at terahertz frequencies is a very important open challenge made difficult by the intrinsically lossy propagation of terahertz radiation in current non-reciprocal materials. Here we report the design, fabrication and measurement of a terahertz non-reciprocal isolator for circularly polarized waves based on magnetostatically biased monolayer graphene, operating in reflection. The device exploits the non-reciprocal optical conductivity of graphene and, in spite of its simple design, it exhibits almost 20 dB of isolation and only 7.5 dB of insertion loss at 2.9 THz. Operation with linearly polarized light can be achieved using quarter-wave plates as polarization converters. These results demonstrate the superiority of graphene with respect to currently used terahertz non-reciprocal materials and pave the way to a novel class of optimal non-reciprocal devices. PMID:27048760

  2. Near optimal graphene terahertz non-reciprocal isolator.

    PubMed

    Tamagnone, Michele; Moldovan, Clara; Poumirol, Jean-Marie; Kuzmenko, Alexey B; Ionescu, Adrian M; Mosig, Juan R; Perruisseau-Carrier, Julien

    2016-01-01

    Isolators, or optical diodes, are devices enabling unidirectional light propagation by using non-reciprocal optical materials, namely materials able to break Lorentz reciprocity. The realization of isolators at terahertz frequencies is a very important open challenge made difficult by the intrinsically lossy propagation of terahertz radiation in current non-reciprocal materials. Here we report the design, fabrication and measurement of a terahertz non-reciprocal isolator for circularly polarized waves based on magnetostatically biased monolayer graphene, operating in reflection. The device exploits the non-reciprocal optical conductivity of graphene and, in spite of its simple design, it exhibits almost 20 dB of isolation and only 7.5 dB of insertion loss at 2.9 THz. Operation with linearly polarized light can be achieved using quarter-wave plates as polarization converters. These results demonstrate the superiority of graphene with respect to currently used terahertz non-reciprocal materials and pave the way to a novel class of optimal non-reciprocal devices. PMID:27048760

  3. Gait characteristic analysis and identification based on the iPhone's accelerometer and gyrometer.

    PubMed

    Sun, Bing; Wang, Yang; Banda, Jacob

    2014-01-01

    Gait identification is a valuable approach to identify humans at a distance. In this paper, gait characteristics are analyzed based on an iPhone's accelerometer and gyrometer,and a new approach is proposed for gait identification. Specifically, gait datasets are collected by the triaxial accelerometer and gyrometer embedded in an iPhone. Then, the datasets are processed to extract gait characteristic parameters which include gait frequency, symmetry coefficient, dynamic range and similarity coefficient of characteristic curves. Finally, a weighted voting scheme dependent upon the gait characteristic parameters is proposed forgait identification. Four experiments are implemented to validate the proposed scheme. The attitude and acceleration solutions are verified by simulation. Then the gait characteristics are analyzed by comparing two sets of actual data, and the performance of the weighted voting identification scheme is verified by 40 datasets of 10 subjects. PMID:25222034

  4. Gait characteristic analysis and identification based on the iPhone's accelerometer and gyrometer.

    PubMed

    Sun, Bing; Wang, Yang; Banda, Jacob

    2014-09-12

    Gait identification is a valuable approach to identify humans at a distance. In this paper, gait characteristics are analyzed based on an iPhone's accelerometer and gyrometer,and a new approach is proposed for gait identification. Specifically, gait datasets are collected by the triaxial accelerometer and gyrometer embedded in an iPhone. Then, the datasets are processed to extract gait characteristic parameters which include gait frequency, symmetry coefficient, dynamic range and similarity coefficient of characteristic curves. Finally, a weighted voting scheme dependent upon the gait characteristic parameters is proposed forgait identification. Four experiments are implemented to validate the proposed scheme. The attitude and acceleration solutions are verified by simulation. Then the gait characteristics are analyzed by comparing two sets of actual data, and the performance of the weighted voting identification scheme is verified by 40 datasets of 10 subjects.

  5. Reciprocity and gyrotropism in magnetic resonance transduction

    SciTech Connect

    Tropp, James

    2006-12-15

    We give formulas for transduction in magnetic resonance - i.e., the appearance of an emf due to Larmor precession of spins - based upon the modified Lorentz reciprocity principle for gyrotropic (also called 'nonreciprocal') media, i.e., in which a susceptibility tensor is carried to its transpose by reversal of an external static field [cf., R. F. Harrington and A. T. Villeneuve IRE Trans. Microwave Theory and Technique MTT6, 308 (1958)]. Prior applications of reciprocity to magnetic resonance, despite much success, have ignored the gyrotropism which necessarily arises due to nuclear and/or unpaired electronic spins. For detection with linearly polarized fields, oscillating at the Larmor frequency, the emf is written in terms of a volume integral containing a product of two factors which we define as the antenna patterns, i.e. (H{sub 1x}{+-}iH{sub 1y}), where, e.g., for a single transceive antenna, the H's are just the spatially dependent oscillatory magnetic field strengths, per the application of some reference current at the antenna terminals, with the negative sign obtaining for transmission, and the positive for reception. Similar expressions hold for separate transmit and receive antennas; expressions are also given for circular polarization of the fields. We then exhibit a receive-only array antenna of two elements for magnetic resonance imaging of protons, which, due an intensity artifact arising from stray reactive coupling of the elements, produces, despite its own bilateral symmetry, asymmetric proton NMR images of a symmetric cylindrical phantom containing aqueous saline solution [J. Tropp and T. Schirmer, J. Magn. Reson. 151, 146 (2001)]. Modification of this two-port antenna, to function in transmit-receive mode, allows us to demonstrate highly nonreciprocal behavior: that is, to record images (of cylindrical test phantoms containing aqueous saline solution) whose appearance dramatically changes, when the roles of transmission and reception are

  6. An adaptive gyroscope-based algorithm for temporal gait analysis.

    PubMed

    Greene, Barry R; McGrath, Denise; O'Neill, Ross; O'Donovan, Karol J; Burns, Adrian; Caulfield, Brian

    2010-12-01

    Body-worn kinematic sensors have been widely proposed as the optimal solution for portable, low cost, ambulatory monitoring of gait. This study aims to evaluate an adaptive gyroscope-based algorithm for automated temporal gait analysis using body-worn wireless gyroscopes. Gyroscope data from nine healthy adult subjects performing four walks at four different speeds were then compared against data acquired simultaneously using two force plates and an optical motion capture system. Data from a poliomyelitis patient, exhibiting pathological gait walking with and without the aid of a crutch, were also compared to the force plate. Results show that the mean true error between the adaptive gyroscope algorithm and force plate was -4.5 ± 14.4 ms and 43.4 ± 6.0 ms for IC and TC points, respectively, in healthy subjects. Similarly, the mean true error when data from the polio patient were compared against the force plate was -75.61 ± 27.53 ms and 99.20 ± 46.00 ms for IC and TC points, respectively. A comparison of the present algorithm against temporal gait parameters derived from an optical motion analysis system showed good agreement for nine healthy subjects at four speeds. These results show that the algorithm reported here could constitute the basis of a robust, portable, low-cost system for ambulatory monitoring of gait.

  7. Emotion recognition using Kinect motion capture data of human gaits

    PubMed Central

    Li, Shun; Cui, Liqing; Zhu, Changye; Li, Baobin

    2016-01-01

    Automatic emotion recognition is of great value in many applications, however, to fully display the application value of emotion recognition, more portable, non-intrusive, inexpensive technologies need to be developed. Human gaits could reflect the walker’s emotional state, and could be an information source for emotion recognition. This paper proposed a novel method to recognize emotional state through human gaits by using Microsoft Kinect, a low-cost, portable, camera-based sensor. Fifty-nine participants’ gaits under neutral state, induced anger and induced happiness were recorded by two Kinect cameras, and the original data were processed through joint selection, coordinate system transformation, sliding window gauss filtering, differential operation, and data segmentation. Features of gait patterns were extracted from 3-dimentional coordinates of 14 main body joints by Fourier transformation and Principal Component Analysis (PCA). The classifiers NaiveBayes, RandomForests, LibSVM and SMO (Sequential Minimal Optimization) were trained and evaluated, and the accuracy of recognizing anger and happiness from neutral state achieved 80.5% and 75.4%. Although the results of distinguishing angry and happiness states were not ideal in current study, it showed the feasibility of automatically recognizing emotional states from gaits, with the characteristics meeting the application requirements. PMID:27672492

  8. Muscle Activation during Gait in Children with Duchenne Muscular Dystrophy

    PubMed Central

    Vuillerot, Carole; Tiffreau, Vincent; Peudenier, Sylviane; Cuisset, Jean-Marie; Pereon, Yann; Leboeuf, Fabien; Delporte, Ludovic; Delpierre, Yannick; Gross, Raphaël

    2016-01-01

    The aim of this prospective study was to investigate changes in muscle activity during gait in children with Duchenne muscular Dystrophy (DMD). Dynamic surface electromyography recordings (EMGs) of 16 children with DMD and pathological gait were compared with those of 15 control children. The activity of the rectus femoris (RF), vastus lateralis (VL), medial hamstrings (HS), tibialis anterior (TA) and gastrocnemius soleus (GAS) muscles was recorded and analysed quantitatively and qualitatively. The overall muscle activity in the children with DMD was significantly different from that of the control group. Percentage activation amplitudes of RF, HS and TA were greater throughout the gait cycle in the children with DMD and the timing of GAS activity differed from the control children. Significantly greater muscle coactivation was found in the children with DMD. There were no significant differences between sides. Since the motor command is normal in DMD, the hyper-activity and co-contractions likely compensate for gait instability and muscle weakness, however may have negative consequences on the muscles and may increase the energy cost of gait. Simple rehabilitative strategies such as targeted physical therapies may improve stability and thus the pattern of muscle activity. PMID:27622734

  9. Robust Gait-Based Person Identification against Walking Speed Variations

    NASA Astrophysics Data System (ADS)

    Aqmar, Muhammad Rasyid; Shinoda, Koichi; Furui, Sadaoki

    Variations in walking speed have a strong impact on gait-based person identification. We propose a method that is robust against walking-speed variations. It is based on a combination of cubic higher-order local auto-correlation (CHLAC), gait silhouette-based principal component analysis (GSP), and a statistical framework using hidden Markov models (HMMs). The CHLAC features capture the within-phase spatio-temporal characteristics of each individual, the GSP features retain more shape/phase information for better gait sequence alignment, and the HMMs classify the ID of each gait even when walking speed changes nonlinearly. We compared the performance of our method with other conventional methods using five different databases, SOTON, USF-NIST, CMU-MoBo, TokyoTech A and TokyoTech B. The proposed method was equal to or better than the others when the speed did not change greatly, and it was significantly better when the speed varied across and within a gait sequence.

  10. Secure and privacy enhanced gait authentication on smart phone.

    PubMed

    Hoang, Thang; Choi, Deokjai

    2014-01-01

    Smart environments established by the development of mobile technology have brought vast benefits to human being. However, authentication mechanisms on portable smart devices, particularly conventional biometric based approaches, still remain security and privacy concerns. These traditional systems are mostly based on pattern recognition and machine learning algorithms, wherein original biometric templates or extracted features are stored under unconcealed form for performing matching with a new biometric sample in the authentication phase. In this paper, we propose a novel gait based authentication using biometric cryptosystem to enhance the system security and user privacy on the smart phone. Extracted gait features are merely used to biometrically encrypt a cryptographic key which is acted as the authentication factor. Gait signals are acquired by using an inertial sensor named accelerometer in the mobile device and error correcting codes are adopted to deal with the natural variation of gait measurements. We evaluate our proposed system on a dataset consisting of gait samples of 34 volunteers. We achieved the lowest false acceptance rate (FAR) and false rejection rate (FRR) of 3.92% and 11.76%, respectively, in terms of key length of 50 bits. PMID:24955403

  11. Analysis of foot load during ballet dancers' gait.

    PubMed

    Prochazkova, Marketa; Tepla, Lucie; Svoboda, Zdenek; Janura, Miroslav; Cieslarová, Miloslava

    2014-01-01

    Ballet is an art that puts extreme demands on the dancer's musculoskeletal system and therefore significantly affects motor behavior of the dancers. The aim of our research was to compare plantar pressure distribution during stance phase of gait between a group of professional ballet dancers and non-dancers. Thirteen professional dancers (5 men, 8 women; mean age of 24.1 ± 3.8 years) and 13 nondancers (5 men, 8 women; mean age of 26.1 ± 5.3 years) participated in this study. Foot pressure analysis during gait was collected using a 2 m pressure plate. The participants were instructed to walk across the platform at a self-selected pace barefoot. Three gait cycles were necessary for the data analysis. The results revealed higher (p < 0.05) pressure peaks in medial edge of forefoot during gait for dancers in comparison with nondancers. Furthermore, differences in total foot loading and foot loading duration of rearfoot was higher (p < 0.05) in dancers as well. We can attribute these differences to long-term and intensive dancing exercises that can change the dancer's gait stereotype. PMID:25088458

  12. Secure and Privacy Enhanced Gait Authentication on Smart Phone

    PubMed Central

    Choi, Deokjai

    2014-01-01

    Smart environments established by the development of mobile technology have brought vast benefits to human being. However, authentication mechanisms on portable smart devices, particularly conventional biometric based approaches, still remain security and privacy concerns. These traditional systems are mostly based on pattern recognition and machine learning algorithms, wherein original biometric templates or extracted features are stored under unconcealed form for performing matching with a new biometric sample in the authentication phase. In this paper, we propose a novel gait based authentication using biometric cryptosystem to enhance the system security and user privacy on the smart phone. Extracted gait features are merely used to biometrically encrypt a cryptographic key which is acted as the authentication factor. Gait signals are acquired by using an inertial sensor named accelerometer in the mobile device and error correcting codes are adopted to deal with the natural variation of gait measurements. We evaluate our proposed system on a dataset consisting of gait samples of 34 volunteers. We achieved the lowest false acceptance rate (FAR) and false rejection rate (FRR) of 3.92% and 11.76%, respectively, in terms of key length of 50 bits. PMID:24955403

  13. Muscle Activation during Gait in Children with Duchenne Muscular Dystrophy.

    PubMed

    Ropars, Juliette; Lempereur, Mathieu; Vuillerot, Carole; Tiffreau, Vincent; Peudenier, Sylviane; Cuisset, Jean-Marie; Pereon, Yann; Leboeuf, Fabien; Delporte, Ludovic; Delpierre, Yannick; Gross, Raphaël; Brochard, Sylvain

    2016-01-01

    The aim of this prospective study was to investigate changes in muscle activity during gait in children with Duchenne muscular Dystrophy (DMD). Dynamic surface electromyography recordings (EMGs) of 16 children with DMD and pathological gait were compared with those of 15 control children. The activity of the rectus femoris (RF), vastus lateralis (VL), medial hamstrings (HS), tibialis anterior (TA) and gastrocnemius soleus (GAS) muscles was recorded and analysed quantitatively and qualitatively. The overall muscle activity in the children with DMD was significantly different from that of the control group. Percentage activation amplitudes of RF, HS and TA were greater throughout the gait cycle in the children with DMD and the timing of GAS activity differed from the control children. Significantly greater muscle coactivation was found in the children with DMD. There were no significant differences between sides. Since the motor command is normal in DMD, the hyper-activity and co-contractions likely compensate for gait instability and muscle weakness, however may have negative consequences on the muscles and may increase the energy cost of gait. Simple rehabilitative strategies such as targeted physical therapies may improve stability and thus the pattern of muscle activity. PMID:27622734

  14. Secure and privacy enhanced gait authentication on smart phone.

    PubMed

    Hoang, Thang; Choi, Deokjai

    2014-01-01

    Smart environments established by the development of mobile technology have brought vast benefits to human being. However, authentication mechanisms on portable smart devices, particularly conventional biometric based approaches, still remain security and privacy concerns. These traditional systems are mostly based on pattern recognition and machine learning algorithms, wherein original biometric templates or extracted features are stored under unconcealed form for performing matching with a new biometric sample in the authentication phase. In this paper, we propose a novel gait based authentication using biometric cryptosystem to enhance the system security and user privacy on the smart phone. Extracted gait features are merely used to biometrically encrypt a cryptographic key which is acted as the authentication factor. Gait signals are acquired by using an inertial sensor named accelerometer in the mobile device and error correcting codes are adopted to deal with the natural variation of gait measurements. We evaluate our proposed system on a dataset consisting of gait samples of 34 volunteers. We achieved the lowest false acceptance rate (FAR) and false rejection rate (FRR) of 3.92% and 11.76%, respectively, in terms of key length of 50 bits.

  15. Quality of Life and Gait in Elderly Group

    PubMed Central

    Taguchi, Carlos Kazuo; Teixeira, Jacqueline Pitanga; Alves, Lucas Vieira; Oliveira, Priscila Feliciano; Raposo, Oscar Felipe Falcão

    2015-01-01

    Introduction  The process of aging could lead to seniors being more prone to falls, which affects their quality of life. Objective  The objective of this study is to investigate the relationship between quality of life and gait in the elderly. Methods  We used World Health Organization Quality of Life-Brief (WHOQOL-Brief) Brazilian version and the Dynamic Gait Index to assess fifty-six volunteers from the northeast of Brazil. Ages ranged from 60 to 85 years. Results  The Dynamic Gait Index, which indicates the probability of falls, resulted in 36.3% of the sample presenting abnormal results. There was correlation between domain 2 (psychological) and domain 4 (environment) with domain 1(Physical) and domain 3 (Social); a negative correlation between age and Domain 2; correlation between Question 1 (How would you rate your quality of life?) and domains 1, 2, and 4 and no correlation between questions 1 and 2 (How satisfied are you with your health?). Question 2 was correlated with all of the domains. There was negative association between question 1 and falls, and a slight correlation between the Dynamic Gait Index scores and Question 1. Conclusion  The self-perception of the study group about their quality of life was either good or very good, even though a considerable percentage of individuals had suffered falls or reported gait disturbances. PMID:27413405

  16. [Development of a robotic walking simulator for gait rehabilitation].

    PubMed

    Schmidt, H; Sorowka, D; Hesse, S; Bernhardt, R

    2003-10-01

    Restoration of gait is a major concern of rehabilitation after stroke or spinal cord injury. Modern concepts of motor learning favour a task-specific repetitive approach, i.e. "whoever wants to learn to walk again must walk." However, the physical demands this places on the therapist, is a limiting factor in the clinical routine setting. This article describes a robotic walking simulator for gait training that enables wheelchair-bound subjects to freely carry out repetitive practicing of an individually adapted gait pattern under simulation of the manual guidance of an experienced therapist. The technical principle applied makes use of programmable footplates with permanent foot/machine contact in combination with compliance control. The solution chosen comprises a planar parallel-serial hybrid kinematic system with three degrees of freedom that moves the feet in the sagittal plane. Gait analysis while floor walking and stair climbing, clinical practicability and safety aspects were the basis for the design. A variable compliance control enables man-machine interaction, ranging from purely position controlled movement to full compliance during swing phase above a virtual ground profile. In full compliance mode the robotic walking simulator behaves like a haptic device. The concept presented offers new prospects for individualized gait rehabilitation.

  17. Coexistence of Gait Disturbances and Chorea in Experimental Huntington's Disease.

    PubMed

    Casaca-Carreira, João; Temel, Yasin; van Zelst, Marloes; Jahanshahi, Ali

    2015-01-01

    Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by an expanded CAG repeat. The clinical features are progressive motor dysfunction, cognitive deterioration, and psychiatric disturbances. Unpredictable choreic movements, among the most characteristic hallmarks, may contribute to gait disturbances and loss of balance in HD individuals. In this study, we aimed to investigate and characterize the gait abnormalities and choreic movements in a transgenic rat model of HD (tgHD). TgHD presents typical neuropathological, neurophysiological, and behavioral aspects mimicking some of the key features of human HD and is the only described experimental model for HD that exhibits choreiform movements. We used the Catwalk, with emphasis on static and dynamic gait parameters, to test the hypothesis that at symptomatic age (9 months) the dynamic measures of gait in HD are altered and coexist with choreiform movements. Our results showed that the dynamic parameters seem to be more affected than static parameters at this age in tgHD rats. The number of steps and step cycles and swing speed of the paws were increased in tgHD rat in comparison to wild-type controls. Our study demonstrates that gait abnormalities coexist with chorea rather than being caused by it. These symptoms may originate from distinct networks in the basal ganglia and downstream connections. PMID:26063966

  18. Emotion recognition using Kinect motion capture data of human gaits

    PubMed Central

    Li, Shun; Cui, Liqing; Zhu, Changye; Li, Baobin

    2016-01-01

    Automatic emotion recognition is of great value in many applications, however, to fully display the application value of emotion recognition, more portable, non-intrusive, inexpensive technologies need to be developed. Human gaits could reflect the walker’s emotional state, and could be an information source for emotion recognition. This paper proposed a novel method to recognize emotional state through human gaits by using Microsoft Kinect, a low-cost, portable, camera-based sensor. Fifty-nine participants’ gaits under neutral state, induced anger and induced happiness were recorded by two Kinect cameras, and the original data were processed through joint selection, coordinate system transformation, sliding window gauss filtering, differential operation, and data segmentation. Features of gait patterns were extracted from 3-dimentional coordinates of 14 main body joints by Fourier transformation and Principal Component Analysis (PCA). The classifiers NaiveBayes, RandomForests, LibSVM and SMO (Sequential Minimal Optimization) were trained and evaluated, and the accuracy of recognizing anger and happiness from neutral state achieved 80.5% and 75.4%. Although the results of distinguishing angry and happiness states were not ideal in current study, it showed the feasibility of automatically recognizing emotional states from gaits, with the characteristics meeting the application requirements.

  19. Accurate and Reliable Gait Cycle Detection in Parkinson's Disease.

    PubMed

    Hundza, Sandra R; Hook, William R; Harris, Christopher R; Mahajan, Sunny V; Leslie, Paul A; Spani, Carl A; Spalteholz, Leonhard G; Birch, Benjamin J; Commandeur, Drew T; Livingston, Nigel J

    2014-01-01

    There is a growing interest in the use of Inertial Measurement Unit (IMU)-based systems that employ gyroscopes for gait analysis. We describe an improved IMU-based gait analysis processing method that uses gyroscope angular rate reversal to identify the start of each gait cycle during walking. In validation tests with six subjects with Parkinson disease (PD), including those with severe shuffling gait patterns, and seven controls, the probability of True-Positive event detection and False-Positive event detection was 100% and 0%, respectively. Stride time validation tests using high-speed cameras yielded a standard deviation of 6.6 ms for controls and 11.8 ms for those with PD. These data demonstrate that the use of our angular rate reversal algorithm leads to improvements over previous gyroscope-based gait analysis systems. Highly accurate and reliable stride time measurements enabled us to detect subtle changes in stride time variability following a Parkinson's exercise class. We found unacceptable measurement accuracy for stride length when using the Aminian et al gyro-based biomechanical algorithm, with errors as high as 30% in PD subjects. An alternative method, using synchronized infrared timing gates to measure velocity, combined with accurate mean stride time from our angular rate reversal algorithm, more accurately calculates mean stride length.

  20. Emotion recognition using Kinect motion capture data of human gaits.

    PubMed

    Li, Shun; Cui, Liqing; Zhu, Changye; Li, Baobin; Zhao, Nan; Zhu, Tingshao

    2016-01-01

    Automatic emotion recognition is of great value in many applications, however, to fully display the application value of emotion recognition, more portable, non-intrusive, inexpensive technologies need to be developed. Human gaits could reflect the walker's emotional state, and could be an information source for emotion recognition. This paper proposed a novel method to recognize emotional state through human gaits by using Microsoft Kinect, a low-cost, portable, camera-based sensor. Fifty-nine participants' gaits under neutral state, induced anger and induced happiness were recorded by two Kinect cameras, and the original data were processed through joint selection, coordinate system transformation, sliding window gauss filtering, differential operation, and data segmentation. Features of gait patterns were extracted from 3-dimentional coordinates of 14 main body joints by Fourier transformation and Principal Component Analysis (PCA). The classifiers NaiveBayes, RandomForests, LibSVM and SMO (Sequential Minimal Optimization) were trained and evaluated, and the accuracy of recognizing anger and happiness from neutral state achieved 80.5% and 75.4%. Although the results of distinguishing angry and happiness states were not ideal in current study, it showed the feasibility of automatically recognizing emotional states from gaits, with the characteristics meeting the application requirements. PMID:27672492