Science.gov

Sample records for walking

  1. Walking Problems

    MedlinePLUS

    ... daily activities, get around, and exercise. Having a problem with walking can make daily life more difficult. ... walk is called your gait. A variety of problems can cause an abnormal gait and lead to ...

  2. Lvy walks

    NASA Astrophysics Data System (ADS)

    Zaburdaev, V.; Denisov, S.; Klafter, J.

    2015-04-01

    Random walk is a fundamental concept with applications ranging from quantum physics to econometrics. Remarkably, one specific model of random walks appears to be ubiquitous across many fields as a tool to analyze transport phenomena in which the dispersal process is faster than dictated by Brownian diffusion. The Lvy-walk model combines two key features, the ability to generate anomalously fast diffusion and a finite velocity of a random walker. Recent results in optics, Hamiltonian chaos, cold atom dynamics, biophysics, and behavioral science demonstrate that this particular type of random walk provides significant insight into complex transport phenomena. This review gives a self-consistent introduction to Lvy walks, surveys their existing applications, including latest advances, and outlines further perspectives.

  3. Walking Perception by Walking Observers

    ERIC Educational Resources Information Center

    Jacobs, Alissa; Shiffrar, Maggie

    2005-01-01

    People frequently analyze the actions of other people for the purpose of action coordination. To understand whether such self-relative action perception differs from other-relative action perception, the authors had observers either compare their own walking speed with that of a point-light walker or compare the walking speeds of 2 point-light

  4. Coyote Walking

    USGS Multimedia Gallery

    A coyote walking in dry creek bed of streamside scrub vegetation dominated by the native plant, mule fat (Baccharis salidifolia), about 20 days before the fire. In their wildlife research, USGS scientists position camera traps along trails and dry creek beds, places that are likely to be travel rout...

  5. Quantum random walks without walking

    SciTech Connect

    Manouchehri, K.; Wang, J. B.

    2009-12-15

    Quantum random walks have received much interest due to their nonintuitive dynamics, which may hold the key to a new generation of quantum algorithms. What remains a major challenge is a physical realization that is experimentally viable and not limited to special connectivity criteria. We present a scheme for walking on arbitrarily complex graphs, which can be realized using a variety of quantum systems such as a Bose-Einstein condensate trapped inside an optical lattice. This scheme is particularly elegant since the walker is not required to physically step between the nodes; only flipping coins is sufficient.

  6. Fire-Walking

    ERIC Educational Resources Information Center

    Willey, David

    2010-01-01

    This article gives a brief history of fire-walking and then deals with the physics behind fire-walking. The author has performed approximately 50 fire-walks, took the data for the world's hottest fire-walk and was, at one time, a world record holder for the longest fire-walk (www.dwilley.com/HDATLTW/Record_Making_Firewalks.html). He currently…

  7. Fire-Walking

    ERIC Educational Resources Information Center

    Willey, David

    2010-01-01

    This article gives a brief history of fire-walking and then deals with the physics behind fire-walking. The author has performed approximately 50 fire-walks, took the data for the world's hottest fire-walk and was, at one time, a world record holder for the longest fire-walk (www.dwilley.com/HDATLTW/Record_Making_Firewalks.html). He currently

  8. Relation between random walks and quantum walks

    NASA Astrophysics Data System (ADS)

    Boettcher, Stefan; Falkner, Stefan; Portugal, Renato

    2015-05-01

    Based on studies of four specific networks, we conjecture a general relation between the walk dimensions dw of discrete-time random walks and quantum walks with the (self-inverse) Grover coin. In each case, we find that dw of the quantum walk takes on exactly half the value found for the classical random walk on the same geometry. Since walks on homogeneous lattices satisfy this relation trivially, our results for heterogeneous networks suggest that such a relation holds irrespective of whether translational invariance is maintained or not. To develop our results, we extend the renormalization-group analysis (RG) of the stochastic master equation to one with a unitary propagator. As in the classical case, the solution ? (x ,t ) in space and time of this quantum-walk equation exhibits a scaling collapse for a variable xdw/t in the weak limit, which defines dw and illuminates fundamental aspects of the walk dynamics, e.g., its mean-square displacement. We confirm the collapse for ? (x ,t ) in each case with extensive numerical simulation. The exact values for dw themselves demonstrate that RG is a powerful complementary approach to study the asymptotics of quantum walks that weak-limit theorems have not been able to access, such as for systems lacking translational symmetries beyond simple trees.

  9. Walking Wellness. Student Workbook.

    ERIC Educational Resources Information Center

    Sweetgall, Robert; Neeves, Robert

    This comprehensive student text and workbook, for grades four through eight, contains 16 workshop units focusing on walking field trips, aerobic pacing concepts, walking techniques, nutrition, weight control and healthy life-style planning. Co-ordinated homework assignments are included. The appendixes include 10 tips for walking, a calorie chart,

  10. Quantum walk computation

    SciTech Connect

    Kendon, Viv

    2014-12-04

    Quantum versions of random walks have diverse applications that are motivating experimental implementations as well as theoretical studies. Recent results showing quantum walks are “universal for quantum computation” relate to algorithms, to be run on quantum computers. We consider whether an experimental implementation of a quantum walk could provide useful computation before we have a universal quantum computer.

  11. Walking Wellness. Student Workbook.

    ERIC Educational Resources Information Center

    Sweetgall, Robert; Neeves, Robert

    This comprehensive student text and workbook, for grades four through eight, contains 16 workshop units focusing on walking field trips, aerobic pacing concepts, walking techniques, nutrition, weight control and healthy life-style planning. Co-ordinated homework assignments are included. The appendixes include 10 tips for walking, a calorie chart,…

  12. Walk This Way

    ERIC Educational Resources Information Center

    Mason, Nick

    2007-01-01

    A generation ago, it was part of growing up for all kids when they biked or walked to school. But in the last 30 years, heavier traffic, wider roads and more dangerous intersections have made it riskier for students walking or pedaling. Today, fewer than 15 percent of kids bike or walk to school compared with more than 50 percent in 1969. In the…

  13. Walk This Way

    ERIC Educational Resources Information Center

    Mason, Nick

    2007-01-01

    A generation ago, it was part of growing up for all kids when they biked or walked to school. But in the last 30 years, heavier traffic, wider roads and more dangerous intersections have made it riskier for students walking or pedaling. Today, fewer than 15 percent of kids bike or walk to school compared with more than 50 percent in 1969. In the

  14. Walk Score®

    PubMed Central

    Brown, Scott C.; Pantin, Hilda; Lombard, Joanna; Toro, Matthew; Huang, Shi; Plater-Zyberk, Elizabeth; Perrino, Tatiana; Perez-Gomez, Gianna; Barrera-Allen, Lloyd; Szapocznik, José

    2013-01-01

    Background Walk Score® is a nationally and publicly available metric of neighborhood walkability based on proximity to amenities (e.g., retail, food, schools). However, few studies have examined the relationship of Walk Score to walking behavior. Purpose To examine the relationship of Walk Score to walking behavior in a sample of recent Cuban immigrants, who overwhelmingly report little choice in their selection of neighborhood built environments when they arrive in the U.S. Methods Participants were 391 recent healthy Cuban immigrants (M age=37.1 years) recruited within 90 days of arrival in the U.S., and assessed within 4 months of arrival (M=41.0 days in the U.S.), who resided throughout Miami-Dade County FL. Data on participants’ addresses, walking and sociodemographics were collected prospectively from 2008 to 2010. Analyses conducted in 2011 examined the relationship of Walk Score for each participant’s residential address in the U.S. to purposive walking, controlling for age, gender, education, BMI, days in the U.S., and habitual physical activity level in Cuba. Results For each 10-point increase in Walk Score, adjusting for covariates, there was a significant 19% increase in the likelihood of purposive walking, a 26% increase in the likelihood of meeting physical activity recommendations by walking, and 27% more minutes walked in the previous week. Conclusions Results suggest that Walk Score is associated with walking in a sample of recent immigrants who initially had little choice in where they lived in the U.S. These results support existing guidelines indicating that mixed land use (such as parks and restaurants near homes) should be included when designing walkable communities. PMID:23867028

  15. Walking on music.

    PubMed

    Styns, Frederik; van Noorden, Leon; Moelants, Dirk; Leman, Marc

    2007-10-01

    The present study focuses on the intricate relationship between human body movement and music, in particular on how music may influence the way humans walk. In an experiment, participants were asked to synchronize their walking tempo with the tempo of musical and metronome stimuli. The walking tempo and walking speed were measured. The tempi of the stimuli varied between 50 and 190 beats per minute. The data revealed that people walk faster on music than on metronome stimuli and that walking on music can be modeled as a resonance phenomenon that is related to the perceptual resonance phenomenon as described by Van Noorden and Moelants (Van Noorden, L., & Moelants, D. (1999). Resonance in the perception of musical pulse. Journal of New Music Research, 28, 43-66). PMID:17910985

  16. Anyonic quantum walks

    SciTech Connect

    Brennen, Gavin K.; Ellinas, Demosthenes; Kendon, Viv; Pachos, Jiannis K. Tsohantjis, Ioannis; Wang Zhenghan

    2010-03-15

    The one dimensional quantum walk of anyonic systems is presented. The anyonic walker performs braiding operations with stationary anyons of the same type ordered canonically on the line of the walk. Abelian as well as non-Abelian anyons are studied and it is shown that they have very different properties. Abelian anyonic walks demonstrate the expected quadratic quantum speedup. Non-Abelian anyonic walks are much more subtle. The exponential increase of the system's Hilbert space and the particular statistical evolution of non-Abelian anyons give a variety of new behaviors. The position distribution of the walker is related to Jones polynomials, topological invariants of the links created by the anyonic world-lines during the walk. Several examples such as the SU(2){sub k} and the quantum double models are considered that provide insight to the rich diffusion properties of anyons.

  17. Quantum walks on simplicial complexes

    NASA Astrophysics Data System (ADS)

    Matsue, Kaname; Ogurisu, Osamu; Segawa, Etsuo

    2016-02-01

    We construct a new type of quantum walks on simplicial complexes as a natural extension of the well-known Szegedy walk on graphs. One can numerically observe that our proposing quantum walks possess linear spreading and localization as in the case of the Grover walk on lattices. Moreover, our numerical simulation suggests that localization of our quantum walks reflects not only topological but also geometric structures. On the other hand, our proposing quantum walk contains an intrinsic problem concerning exhibition of non-trivial behavior, which is not seen in typical quantum walks such as Grover walks on graphs.

  18. Walking Humanoid Robot Lola

    NASA Astrophysics Data System (ADS)

    Schwienbacher, Markus; Favot, Valerio; Buschmann, Thomas; Lohmeier, Sebastian; Ulbrich, Heinz

    Based on the experience gathered from the walking robot Johnnie the new performance enhanced 25-DoF humanoid robot Lola was built. The goal of this project is to realize a fast, human-like walking. This paper presents different aspects of this complex mechatronic system. Besides the overall lightweight construction, custom build multi-sensory joint drives with high torque brush-less motors were crucial for reaching the performance goal. A decentralized electronics architecture is used for joint control and sensor data processing. A simulation environment serves as a testbed for the walking control, to minimize the risk of damaging the robot hardware during real world experiments.

  19. Normal and hemiparetic walking

    NASA Astrophysics Data System (ADS)

    Pfeiffer, Friedrich; König, Eberhard

    2013-01-01

    The idea of a model-based control of rehabilitation for hemiparetic patients requires efficient models of human walking, healthy walking as well as hemiparetic walking. Such models are presented in this paper. They include 42 degrees of freedom and allow especially the evaluation of kinetic magnitudes with the goal to evaluate measures for the hardness of hemiparesis. As far as feasible, the simulations have been compared successfully with measurements, thus improving the confidence level for an application in clinical practice. The paper is mainly based on the dissertation [19].

  20. Walking to health.

    PubMed

    Morris, J N; Hardman, A E

    1997-05-01

    Walking is a rhythmic, dynamic, aerobic activity of large skeletal muscles that confers the multifarious benefits of this with minimal adverse effects. Walking, faster than customary, and regularly in sufficient quantity into the 'training zone' of over 70% of maximal heart rate, develops and sustains physical fitness: the cardiovascular capacity and endurance (stamina) for bodily work and movement in everyday life that also provides reserves for meeting exceptional demands. Muscles of the legs, limb girdle and lower trunk are strengthened and the flexibility of their cardinal joints preserved; posture and carriage may improve. Any amount of walking, and at any pace, expends energy. Hence the potential, long term, of walking for weight control. Dynamic aerobic exercise, as in walking, enhances a multitude of bodily processes that are inherent in skeletal muscle activity, including the metabolism of high density lipoproteins and insulin/glucose dynamics. Walking is also the most common weight-bearing activity, and there are indications at all ages of an increase in related bone strength. The pleasurable and therapeutic, psychological and social dimensions of walking, whilst evident, have been surprisingly little studied. Nor has an economic assessment of the benefits and costs of walking been attempted. Walking is beneficial through engendering improved fitness and/or greater physiological activity and energy turnover. Two main modes of such action are distinguished as: (i) acute, short term effects of the exercise; and (ii) chronic, cumulative adaptations depending on habitual activity over weeks and months. Walking is often included in studies of exercise in relation to disease but it has seldom been specifically tested. There is, nevertheless, growing evidence of gains in the prevention of heart attack and reduction of total death rates, in the treatment of hypertension, intermittent claudication and musculoskeletal disorders, and in rehabilitation after heart attack and in chronic respiratory disease. Walking is the most natural activity and the only sustained dynamic aerobic exercise that is common to everyone except for the seriously disabled or very frail. No special skills or equipment are required. Walking is convenient and may be accommodated in occupational and domestic routines. It is self-regulated in intensity, duration and frequency, and, having a low ground impact, is inherently safe. Unlike so much physical activity, there is little, if any, decline in middle age. It is a year-round, readily repeatable, self-reinforcing, habit-forming activity and the main option for increasing physical activity in sedentary populations. Present levels of walking are often low. Familiar social inequalities may be evident. There are indications of a serious decline of walking in children, though further surveys of their activity, fitness and health are required. The downside relates to the incidence of fatal and non-fatal road casualties, especially among children and old people, and the deteriorating air quality due to traffic fumes which mounting evidence implicates in the several stages of respiratory disease. Walking is ideal as a gentle start-up for the sedentary, including the inactive, immobile elderly, bringing a bonus of independence and social well-being. As general policy, a gradual progression is indicated from slow, to regular pace and on to 30 minutes or more of brisk (i.e. 6.4 km/h) walking on most days. These levels should achieve the major gains of activity and health-related fitness without adverse effects. Alternatively, such targets as this can be suggested for personal motivation, clinical practice, and public health. The average middle-aged person should be able to walk 1.6 km comfortably on the level at 6.4 km/h and on a slope of 1 in 20 at 4.8 km/h, however, many cannot do so because of inactivity-induced unfitness. The physiological threshold of 'comfort' represents 70% of maximum heart rate. (ABSTRACT TRUNCATED) PMID:9181668

  1. When Human Walking is a Random Walk

    NASA Astrophysics Data System (ADS)

    Hausdorff, J. M.

    1998-03-01

    The complex, hierarchical locomotor system normally does a remarkable job of controlling an inherently unstable, multi-joint system. Nevertheless, the stride interval --- the duration of a gait cycle --- fluctuates from one stride to the next, even under stationary conditions. We used random walk analysis to study the dynamical properties of these fluctuations under normal conditions and how they change with disease and aging. Random walk analysis of the stride-to-stride fluctuations of healthy, young adult men surprisingly reveals a self-similar pattern: fluctuations at one time scale are statistically similar to those at multiple other time scales (Hausdorff et al, J Appl Phsyiol, 1995). To study the stability of this fractal property, we analyzed data obtained from healthy subjects who walked for 1 hour at their usual pace, as well as at slower and faster speeds. The stride interval fluctuations exhibited long-range correlations with power-law decay for up to a thousand strides at all three walking rates. In contrast, during metronomically-paced walking, these long-range correlations disappeared; variations in the stride interval were uncorrelated and non-fractal (Hausdorff et al, J Appl Phsyiol, 1996). To gain insight into the mechanism(s) responsible for this fractal property, we examined the effects of aging and neurological impairment. Using detrended fluctuation analysis (DFA), we computed α, a measure of the degree to which one stride interval is correlated with previous and subsequent intervals over different time scales. α was significantly lower in healthy elderly subjects compared to young adults (p < .003) and in subjects with Huntington's disease, a neuro-degenerative disorder of the central nervous system, compared to disease-free controls (p < 0.005) (Hausdorff et al, J Appl Phsyiol, 1997). α was also significantly related to degree of functional impairment in subjects with Huntington's disease (r=0.78). Recently, we have observed that just as there are changes with α during aging, there also changes with development. Apparently, the fractal scaling of walking does not become mature until children are eleven years old. Conclusions: The fractal dynamics of spontaneous stride interval fluctuations are normally quite robust and are apparently intrinsic to the healthy adult locomotor system. However, alterations in this fractal scaling property are associated with impairment in central nervous system control, aging and neural development.

  2. Gait or Walking Problems

    MedlinePLUS

    ... numbness, or spasticity (abnormal increase in muscle tone). Visual or cognitive problems can also interfere with walking. ... through the device into the hand and arm. Visual cues may also work. People learn to watch ...

  3. Health Tip: Walk Correctly

    MedlinePLUS

    ... nlm.nih.gov/medlineplus/news/fullstory_154789.html Health Tip: Walk Correctly Tips to avoid hurting yourself ... and Physical Fitness Recent Health News Related MedlinePlus Health Topics Exercise and Physical Fitness About MedlinePlus Site ...

  4. D.U.C.K. Walking.

    ERIC Educational Resources Information Center

    Steller, Jenifer J.

    This manual presents a schoolwide walking program that includes aerobic fitness information, curriculum integration, and walking tours. "Discover and Understand Carolina Kids by Walking" is D.U.C.K. Walking. An aerobic walking activity, D.U.C.K. Walking has two major goals: (1) to promote regular walking as a way to exercise at any age; and (2) to

  5. Walking at stability's edge

    NASA Astrophysics Data System (ADS)

    Milton, John; Nichols, David; Coleman, Adam; Clemens, Coury; Nguyentat, Annie; Radunskaya, Ami

    2007-03-01

    During self-paced human walking, the variability in inter- stride intervals exhibit fractal dynamics characterized by long--range correlations having a power-law decay with exponent ?. We used diffusion fluctuation analysis (DFA) to estimate ? as a function of the roughness of the walking surface for eight (8) healthy subjects (1200-1400 inter- stride intervals for each walking surface). For each subject the highest ? (mean 0.96, range 0.88- 1.10) occured for walking on a running track and ? was 15-20% lower for walking on either a relatively smoother (tennis hard court) or a rougher (dirt path) surface. These observations are captured by a stochastic discrete time cubic map: Ii+1=a(?i)Ii- bI^3i+ ?i, where Ii is the i--th inter--stride time, a(?i)=ao(?) + ?i describes parametric, colored noise where a0(?) is a constant that depends on surface roughness and ?i is colored noise with mean zero, ?i is low--intensity additive white noise, and b is a constant. As the roughness, and hence a0(?), of the walking surface increases, the fluctuations in the inter--stride interval are predicted to obey a power law whose exponent changes non-monotonically: the highest values of ? determined with DFA occur when a0(?) is close to the deterministic stability boundary a=1. Thus the neural control of walking appears to involve a dynamical system tuned close to the edge of stability subjected to the effects of parametric noise.

  6. Walks on SPR neighborhoods.

    PubMed

    Caceres, Alan Joseph J; Castillo, Juan; Lee, Jinnie; St John, Katherine

    2013-01-01

    A nearest-neighbor-interchange (NNI)-walk is a sequence of unrooted phylogenetic trees, T1, T2, . . . , T(k) where each consecutive pair of trees differs by a single NNI move. We give tight bounds on the length of the shortest NNI-walks that visit all trees in a subtree-prune-and-regraft (SPR) neighborhood of a given tree. For any unrooted, binary tree, T, on n leaves, the shortest walk takes Θ(n²) additional steps more than the number of trees in the SPR neighborhood. This answers Bryant’s Second Combinatorial Challenge from the Phylogenetics Challenges List, the Isaac Newton Institute, 2011, and the Penny Ante Problem List, 2009. PMID:23702562

  7. Walking with a Slower Friend

    ERIC Educational Resources Information Center

    Bailey, Herb; Kalman, Dan

    2011-01-01

    Fay and Sam go for a walk. Sam walks along the left side of the street while Fay, who walks faster, starts with Sam but walks to a point on the right side of the street and then returns to meet Sam to complete one segment of their journey. We determine Fay's optimal path minimizing segment length, and thus maximizing the number of times they meet

  8. Walking with a Slower Friend

    ERIC Educational Resources Information Center

    Bailey, Herb; Kalman, Dan

    2011-01-01

    Fay and Sam go for a walk. Sam walks along the left side of the street while Fay, who walks faster, starts with Sam but walks to a point on the right side of the street and then returns to meet Sam to complete one segment of their journey. We determine Fay's optimal path minimizing segment length, and thus maximizing the number of times they meet…

  9. Repulsive delayed random walk

    NASA Astrophysics Data System (ADS)

    Hosaka, Tadaaki; Ohira, Toru

    2004-05-01

    We study here a random walk with delayed feedback around an unstable fixed point. It is found that the random walker can be kept longer around the fixed point with larer delay. This is in contrast to the normal role of delay, which is generally thought to be a source of instability. We discuss a possibility of our model to stick balancing experiments.

  10. Walking Out Graphs

    ERIC Educational Resources Information Center

    Shen, Ji

    2009-01-01

    In the Walking Out Graphs Lesson described here, students experience several types of representations used to describe motion, including words, sentences, equations, graphs, data tables, and actions. The most important theme of this lesson is that students have to understand the consistency among these representations and form the habit of

  11. Walking in My Shoes

    ERIC Educational Resources Information Center

    Salia, Hannah

    2010-01-01

    The Walking in My Shoes curriculum at St. Thomas School in Medina, Washington, has been developed to deepen students' understanding of their own heritage and the cultural similarities and differences among their global peers. Exploring the rich diversity of the world's cultural heritage and the interactions of global migrations throughout history,

  12. Deterministic Walks with Choice

    SciTech Connect

    Beeler, Katy E.; Berenhaut, Kenneth S.; Cooper, Joshua N.; Hunter, Meagan N.; Barr, Peter S.

    2014-01-10

    This paper studies deterministic movement over toroidal grids, integrating local information, bounded memory and choice at individual nodes. The research is motivated by recent work on deterministic random walks, and applications in multi-agent systems. Several results regarding passing tokens through toroidal grids are discussed, as well as some open questions.

  13. Take a Planet Walk

    ERIC Educational Resources Information Center

    Schuster, Dwight

    2008-01-01

    Physical models in the classroom "cannot be expected to represent the full-scale phenomenon with complete accuracy, not even in the limited set of characteristics being studied" (AAAS 1990). Therefore, by modifying a popular classroom activity called a "planet walk," teachers can explore upper elementary students' current understandings; create an

  14. Walking Out Graphs

    ERIC Educational Resources Information Center

    Shen, Ji

    2009-01-01

    In the Walking Out Graphs Lesson described here, students experience several types of representations used to describe motion, including words, sentences, equations, graphs, data tables, and actions. The most important theme of this lesson is that students have to understand the consistency among these representations and form the habit of…

  15. Walking for Your Health

    MedlinePLUS

    ... the Go4Life tip sheet Fitness Clothes and Shoes . Download the Tip Sheet Walking for Your Health (PDF, ... Health and Human Services. About Go4Life Policies & Disclaimer Download Acrobat Reader En Español United States Department of ...

  16. The walking robot project

    NASA Technical Reports Server (NTRS)

    Williams, P.; Sagraniching, E.; Bennett, M.; Singh, R.

    1991-01-01

    A walking robot was designed, analyzed, and tested as an intelligent, mobile, and a terrain adaptive system. The robot's design was an application of existing technologies. The design of the six legs modified and combines well understood mechanisms and was optimized for performance, flexibility, and simplicity. The body design incorporated two tripods for walking stability and ease of turning. The electrical hardware design used modularity and distributed processing to drive the motors. The software design used feedback to coordinate the system and simple keystrokes to give commands. The walking machine can be easily adapted to hostile environments such as high radiation zones and alien terrain. The primary goal of the leg design was to create a leg capable of supporting a robot's body and electrical hardware while walking or performing desired tasks, namely those required for planetary exploration. The leg designers intent was to study the maximum amount of flexibility and maneuverability achievable by the simplest and lightest leg design. The main constraints for the leg design were leg kinematics, ease of assembly, degrees of freedom, number of motors, overall size, and weight.

  17. Take a Planet Walk

    ERIC Educational Resources Information Center

    Schuster, Dwight

    2008-01-01

    Physical models in the classroom "cannot be expected to represent the full-scale phenomenon with complete accuracy, not even in the limited set of characteristics being studied" (AAAS 1990). Therefore, by modifying a popular classroom activity called a "planet walk," teachers can explore upper elementary students' current understandings; create an…

  18. A Walk through Time.

    ERIC Educational Resources Information Center

    Renfroe, Mark; Letendre, Wanda

    1996-01-01

    Describes a seventh-grade class project where students constructed a "time tunnel" (a walk-through display with models and exhibits illustrating various themes and eras). Beginning modestly, the tunnel grew over seven years to include 11 different display scenes. Discusses the construction of the project and benefits to the school. (MJP)

  19. Delayed Random Walks and Control

    NASA Astrophysics Data System (ADS)

    Hosaka, Tadaaki; Ohira, Toru

    2006-05-01

    Issues of resonance that appear in non-standard random walk models are discussed. The first walk is called repulsive delayed random walk, which is described in the context of a stick balancing experiment. It will be shown that a type of "resonant" effect takes place to keep the stability of the fixed point better with tuned bias and delay. We also briefly discuss the second model called sticky random walk, which is introduced to model string entanglement. Peculiar resonant effects with respect to these random walks are presented.

  20. [Walking abnormalities in children].

    PubMed

    Segawa, Masaya

    2010-11-01

    Walking is a spontaneous movement termed locomotion that is promoted by activation of antigravity muscles by serotonergic (5HT) neurons. Development of antigravity activity follows 3 developmental epochs of the sleep-wake (S-W) cycle and is modulated by particular 5HT neurons in each epoch. Activation of antigravity activities occurs in the first epoch (around the age of 3 to 4 months) as restriction of atonia in rapid eye movement (REM) stage and development of circadian S-W cycle. These activities strengthen in the second epoch, with modulation of day-time sleep and induction of crawling around the age of 8 months and induction of walking by 1 year. Around the age of 1 year 6 months, absence of guarded walking and interlimb cordination is observed along with modulation of day-time sleep to once in the afternoon. Bipedal walking in upright position occurs in the third epoch, with development of a biphasic S-W cycle by the age of 4-5 years. Patients with infantile autism (IA), Rett syndrome (RTT), or Tourette syndrome (TS) show failure in the development of the first, second, or third epoch, respectively. Patients with IA fail to develop interlimb coordination; those with RTT, crawling and walking; and those with TS, walking in upright posture. Basic pathophysiology underlying these condition is failure in restricting atonia in REM stage; this induces dysfunction of the pedunculopontine nucleus and consequently dys- or hypofunction of the dopamine (DA) neurons. DA hypofunction in the developing brain, associated with compensatory upward regulation of the DA receptors causes psychobehavioral disorders in infancy (IA), failure in synaptogenesis in the frontal cortex and functional development of the motor and associate cortexes in late infancy through the basal ganglia (RTT), and failure in functional development of the prefrontal cortex through the basal ganglia (TS). Further, locomotion failure in early childhood causes failure in development of functional specialization of the cortex through the spinal stepping generator-fastigial nucleus-thalamus-cortex pathway. Early detection of locomotion failure and early adjustment of this condition through environmental factors can prevent the development of higher cortical dysfunction. PMID:21068458

  1. Relativistic Weierstrass random walks.

    PubMed

    Saa, Alberto; Venegeroles, Roberto

    2010-08-01

    The Weierstrass random walk is a paradigmatic Markov chain giving rise to a Lévy-type superdiffusive behavior. It is well known that special relativity prevents the arbitrarily high velocities necessary to establish a superdiffusive behavior in any process occurring in Minkowski spacetime, implying, in particular, that any relativistic Markov chain describing spacetime phenomena must be essentially Gaussian. Here, we introduce a simple relativistic extension of the Weierstrass random walk and show that there must exist a transition time t{c} delimiting two qualitative distinct dynamical regimes: the (nonrelativistic) superdiffusive Lévy flights, for tt{c} . Implications of this crossover between different diffusion regimes are discussed for some explicit examples. The study of such an explicit and simple Markov chain can shed some light on several results obtained in much more involved contexts. PMID:20866862

  2. Mussels realize Weierstrassian Lvy walks as composite correlated random walks

    PubMed Central

    Reynolds, Andy M.

    2014-01-01

    Composite correlated random walks (CCRW) have been posited as a potential replacement for Lvy walks and it has also been suggested that CCRWs have been mistaken for Lvy walks. Here I test an alternative, emerging hypothesis: namely that some organisms approximate Lvy walks as an innate CCRW. It is shown that the tri-modal CCRW found to describe accurately the movement patterns of mussels (Mytilus edulis) during spatial pattern formation in mussel beds can be regarded as being the first three levels in a hierarchy of nested movement patterns which if extended indefinitely would correspond to a Lvy walk whose characteristic (power-law) exponent is tuned to nearly minimize the time required to form patterned beds. The mussels realise this Lvy walk to good approximation across a biologically meaningful range of scales. This demonstrates that the CCRW not only describes mussel movement patterns, it explains them. PMID:24637423

  3. Selection pressures give composite correlated random walks Lvy walk characteristics.

    PubMed

    Reynolds, A M

    2013-09-01

    Composite correlated random walks have been posited as a strong alternative to Lvy walks as models of multi-scale forager movement patterns. Here it is shown that if plastic then intrinsic composite correlated random walks will, under selection pressures, evolve to resemble optimal Lvy walks when foraging is non-destructive. The fittest composite correlated random walkers are found to be those that come closest to being optimal Lvy walkers. This may explain why such a diverse range of foragers have movement patterns that can be approximated by optimal Lvy walks and shows that the 'Lvy-flight foraging' hypothesis has a broad hinterland. The new findings are consistent with recent observations of mussels Mytilus edulis and the Australian desert ant Melophorus bagoti which suggest that animals approximate a Lvy walk by adopting an intrinsic composite movement strategy with different modes. PMID:23665359

  4. Rugged Walking Robot

    NASA Technical Reports Server (NTRS)

    Larimer, Stanley J.; Lisec, Thomas R.; Spiessbach, Andrew J.

    1990-01-01

    Proposed walking-beam robot simpler and more rugged than articulated-leg walkers. Requires less data processing, and uses power more efficiently. Includes pair of tripods, one nested in other. Inner tripod holds power supplies, communication equipment, computers, instrumentation, sampling arms, and articulated sensor turrets. Outer tripod holds mast on which antennas for communication with remote control site and video cameras for viewing local and distant terrain mounted. Propels itself by raising, translating, and lowering tripods in alternation. Steers itself by rotating raised tripod on turntable.

  5. Sticky Random Walks

    NASA Astrophysics Data System (ADS)

    Ohira, Toru; Hosaka, Tadaaki

    2006-03-01

    Entangled strings is something we commonly observe. For example, wires for electrical appliances or communication network cords sometimes require us to disentangle them. We describe here a concept of sticky random walks to gain some insight into this phenomenon. The strings are represented by the trajectory of a random walker. This random walker leaves sticks or marks at certain time intervals. Therefore, a string is represented by this trajectory with these marks on it. By sending out multiple sticky random walkers, we obtained multiple sticky strings. Furthermore, a string is considered as entangled with another when these marks overlap at the same site in space, and not when they are simply crossed. Thus, the string is considered more sticky when there are more marks on it. We tested a situation having multiple sticky strings in a bounded two-dimensional square grid by sending out sticky random walks in this space. We found that in certain situations, the optimal balance between stickiness and number of strings gives most entangled situation.

  6. Random-walk enzymes

    PubMed Central

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-01-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C ? U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics. PMID:26465508

  7. Random-walk enzymes

    NASA Astrophysics Data System (ADS)

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C →U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  8. Quantum stochastic walks: A generalization of classical random walks and quantum walks

    SciTech Connect

    Whitfield, James D.; Rodriguez-Rosario, Cesar A.; Aspuru-Guzik, Alan

    2010-02-15

    We introduce the quantum stochastic walk (QSW), which determines the evolution of a generalized quantum-mechanical walk on a graph that obeys a quantum stochastic equation of motion. Using an axiomatic approach, we specify the rules for all possible quantum, classical, and quantum-stochastic transitions from a vertex as defined by its connectivity. We show how the family of possible QSWs encompasses both the classical random walk (CRW) and the quantum walk (QW) as special cases but also includes more general probability distributions. As an example, we study the QSW on a line and the glued tree of depth three to observe the behavior of the QW-to-CRW transition.

  9. Quantum stochastic walks: A generalization of classical random walks and quantum walks

    SciTech Connect

    Rodriguez-Rosario, Cesar A.; Aspuru-Guzik, Alan; Whitfield, James D.

    2010-02-23

    We introduce the quantum stochastic walk (QSW), which determines the evolution of a generalized quantum-mechanical walk on a graph that obeys a quantum stochastic equation of motion. Using an axiomatic approach, we specify the rules for all possible quantum, classical, and quantum-stochastic transitions from a vertex as defined by its connectivity. We show how the family of possible QSWs encompasses both the classical random walk (CRW) and the quantum walk (QW) as special cases but also includes more general probability distributions. As an example, we study the QSW on a line and the glued tree of depth three to observe the behavior of the QW-to-CRW transition.

  10. Biomechanics of walking with snowshoes.

    PubMed

    Browning, Raymond C; Kurtz, Rebecca N; Kerherve, Hugo

    2012-03-01

    Snowshoeing is a popular form of winter recreation due to the development of lightweight snowshoes that provide flotation, traction, and stability. The purpose of this study was to determine the effects of snowshoes on lower extremity kinematics during level walking. Twelve adults (6 males, 6 females, body mass = 67.5 +/- 10.7kg) completed six 3-minute level walking trials. Subjects walked overground without snowshoes and on packed snow using conventional and flexible tail snowshoes. We placed lightweight inertial/gyroscopic sensors on the sacrum, thigh, shank, and foot. We recorded sensor orientation and calculated hip, knee, and ankle joint angles and angular velocities. Compared to level overground walking, subjects had greater hip and knee flexion during stance and greater hip flexion during swing while snowshoeing. Ankle plantarflexion began during late swing when snowshoeing vs. heel strike during overground walking. Lower extremity kinematics were similar across snowshoe frame designs during level walking. Our results show that snowshoeing on packed snow results in a more flexed leg compared to overground walking and may reflect a strategy to limit the effects of walking with an extended heel. PMID:22518946

  11. Walking indoors, walking outdoors: an fMRI study

    PubMed Central

    Dalla Volta, Riccardo; Fasano, Fabrizio; Cerasa, Antonio; Mangone, Graziella; Quattrone, Aldo; Buccino, Giovanni

    2015-01-01

    An observation/execution matching system for walking has not been assessed yet. The present fMRI study was aimed at assessing whether, as for object-directed actions, an observation/execution matching system is active for walking and whether the spatial context of walking (open or narrow space) recruits different neural correlates. Two experimental conditions were employed. In the execution condition, while being scanned, participants performed walking on a rolling cylinder located just outside the scanner. The same action was performed also while observing a video presenting either an open space (a country field) or a narrow space (a corridor). In the observation condition, participants observed a video presenting an individual walking on the same cylinder on which the actual action was executed, the open space video and the narrow space video, respectively. Results showed common bilateral activations in the dorsal premotor/supplementary motor areas and in the posterior parietal lobe for both execution and observation of walking, thus supporting a matching system for this action. Moreover, specific sectors of the occipital–temporal cortex and the middle temporal gyrus were consistently active when processing a narrow space versus an open one, thus suggesting their involvement in the visuo-motor transformation required when walking in a narrow space. We forward that the present findings may have implications for rehabilitation of gait and sport training. PMID:26483745

  12. Slow-walking inflation

    SciTech Connect

    Erdmenger, Johanna; Halter, Sebastian; Núñez, Carlos; Tasinato, Gianmassimo E-mail: s.halter@physik.uni-muenchen.de E-mail: gianmassimo.tasinato@port.ac.uk

    2013-01-01

    We propose a new model of slow-roll inflation in string cosmology, based on warped throat supergravity solutions displaying 'walking' dynamics, i.e. the coupling constant of the dual gauge theory slowly varies over a range of energy scales. The features of the throat geometry are sourced by a rich field content, given by the dilaton and RR and NS fluxes. By considering the motion of a D3-brane probe in this geometry, we are able to analytically calculate the brane potential in a physically interesting regime. This potential has an inflection point: in its proximity we realize a model of inflation lasting sixty e-foldings, and whose robust predictions are in agreement with current observations. We are also able to interpret some of the most interesting aspects of this scenario in terms of the properties of the QFT dual theory.

  13. Water-walking devices

    NASA Astrophysics Data System (ADS)

    Hu, David L.; Prakash, Manu; Chan, Brian; Bush, John W. M.

    We report recent efforts in the design and construction of water-walking machines inspired by insects and spiders. The fundamental physical constraints on the size, proportion and dynamics of natural water-walkers are enumerated and used as design criteria for analogous mechanical devices. We report devices capable of rowing along the surface, leaping off the surface and climbing menisci by deforming the free surface. The most critical design constraint is that the devices be lightweight and non-wetting. Microscale manufacturing techniques and new man-made materials such as hydrophobic coatings and thermally actuated wires are implemented. Using highspeed cinematography and flow visualization, we compare the functionality and dynamics of our devices with those of their natural counterparts.

  14. Water-walking devices

    NASA Astrophysics Data System (ADS)

    Hu, David L.; Prakash, Manu; Chan, Brian; Bush, John W. M.

    2007-11-01

    We report recent efforts in the design and construction of water-walking machines inspired by insects and spiders. The fundamental physical constraints on the size, proportion and dynamics of natural water-walkers are enumerated and used as design criteria for analogous mechanical devices. We report devices capable of rowing along the surface, leaping off the surface and climbing menisci by deforming the free surface. The most critical design constraint is that the devices be lightweight and non-wetting. Microscale manufacturing techniques and new man-made materials such as hydrophobic coatings and thermally actuated wires are implemented. Using high-speed cinematography and flow visualization, we compare the functionality and dynamics of our devices with those of their natural counterparts.

  15. Energy cost of level walking.

    PubMed

    Mattsson, E

    1989-01-01

    Devices and methods have been developed for determining speed and oxygen cost of level walking. Speed was recorded and controlled using a speedometer cart. Oxygen uptake was determined with an argon-dilution method using a mixing box mounted on a backpack. The method was found valid, coefficient of variation (cv) less than 2.1%, and to give excellent reproducibility with regard to self-selected speed, cv less than 1.9%, predetermined speed, cv less than 1.3%, and to oxygen cost, cv less than 3.2%. Artificially arranged immobility of the knee or instability of the ankle decreased comfortable walking speed 23% and 4% respectively. Oxygen cost increased 23% and 10% respectively. Stabilizing splints allowing some flexion could if possible be advocated, particularly with elderly patients. Patients with coxarthrosis were studied before and after THA. One year after surgery the Harris hip score had increased from 35 to 85 points and maximal walking speed from 62 to 80 m min-1 Oxygen cost had decreased from 0.267 to 0.221 ml kg-1m-1. The onset of and the recovery from complications, as well as differences between patients with uni- and bilateral diseases, were reflected in change in oxygen cost but not in clinical scoring. Patients with moderate gonarthrosis were studied before and after unicompartmental knee prosthetic replacement. No major benefit of preoperative physical therapy, mainly aiming to improve thigh muscle strength, was observed three months after surgery. One year after surgery the patients had improved in clinical score rating and recovered an almost normal walking ability. Measurements of pain and self-selected walking speed were found to be sufficient for assessing effects of treatment in these patients. Patients with severe gonarthrosis had improved in clinical score rating one year after TKR. Oxygen cost of walking was unchanged. An acquired uneconomic walking pattern was considered to be the reason for unimproved walking efficiency. Patients with spastic paraparesis were treated with long-term stretch of the hip adductor muscles. Either the oxygen cost or the blood lactate level was decreased during walking, indicating that even during moderate exercise blood lactate must be taken into consideration when energy cost is measured in these patients. Measurements of walking speed and oxygen cost of level walking were found to be useful objective parametres for assessing walking and to be a valuable supplement to clinical assessment of effects of treatment in patients with walking disorders. PMID:2633329

  16. Constraining walking and custodial technicolor

    SciTech Connect

    Foadi, Roshan; Frandsen, Mads T.; Sannino, Francesco

    2008-05-01

    We show how to constrain the physical spectrum of walking technicolor models via precision measurements and modified Weinberg sum rules. We also study models possessing a custodial symmetry for the S parameter at the effective Lagrangian level - custodial technicolor - and argue that these models cannot emerge from walking-type dynamics. We suggest that it is possible to have a very light spin-one axial (vector) boson. However, in the walking dynamics the associated vector boson is heavy while it is degenerate with the axial in custodial technicolor.

  17. The Effects of Walking Behavior on Mood.

    ERIC Educational Resources Information Center

    Snodgrass, Sara E.; And Others

    Past research has shown that the way one walks reflects one's personality traits and mood states. A study was conducted to examine whether the way one walks can reciprocally affect one's mood. The study tested the hypothesis that walking vigorously would cause a person to feel happier, and that a shuffling walk would cause a person to feel more

  18. Walking Safely in Rural Areas

    MedlinePLUS

    ... provide uneven footing. Often the vehicles on rural roads travel at much higher speeds than walkers are ... walking on or near the side of the road. Go4Life has the following safety tips for those ...

  19. Quantum snake walk on graphs

    SciTech Connect

    Rosmanis, Ansis

    2011-02-15

    I introduce a continuous-time quantum walk on graphs called the quantum snake walk, the basis states of which are fixed-length paths (snakes) in the underlying graph. First, I analyze the quantum snake walk on the line, and I show that, even though most states stay localized throughout the evolution, there are specific states that most likely move on the line as wave packets with momentum inversely proportional to the length of the snake. Next, I discuss how an algorithm based on the quantum snake walk might potentially be able to solve an extended version of the glued trees problem, which asks to find a path connecting both roots of the glued trees graph. To the best of my knowledge, no efficient quantum algorithm solving this problem is known yet.

  20. Walking and jumping spores

    NASA Astrophysics Data System (ADS)

    Marmottant, Philippe

    2012-02-01

    The Equisetum plants, more commonly called ``horsetail,'' emit 50-microns spores that are spherical in shape and present four hygroscopic arms. Under high humidity, the arms are retracted. But under lower humidity, less than 70%, the four arms deploy beautifully. With time-lapse image recordings, we show that under repeated cycles of dry and high humidity, the spores behave as random walkers, since they move by about their size in a different direction at every cycle. The process is apparently stochastic because of the complex shape of the arms and hysteretic friction of the arms on the ground. For some spores, a decrease in humidity level results in very fast jumps, the spores taking off at a typical velocity of a meter per second, as recorded on high-speed camera. With these jumps, they reach centimetric elevations, much larger than their size. The physical mechanism at the root of these ``Levy-flight'' jumps is still under investigation. The walking and jumping phenomena thus provide motility, which we believe is helpful for the understanding of the biological dispersion of the spores. It could also bring biomimetic inspiration to engineer new motile elastic structures.

  1. Persistent personal biases in walking.

    PubMed

    Boeddeker, Norbert; Jetzschke, Simon; Ernst, Marc

    2015-09-01

    Locomotion along a given path in the absence of vision and audition is known to be inaccurate. Here we ask about the nature of these inaccuracies. To this end, we analyzed the performance of participants in three walking experiments involving straight and angle-walking tasks. In the first experiment eight blindfolded participants were guided along paths of different lengths and asked to turn to a target location by an angle of 90 in a sports hall (size: 25x45m). We found significant biases in turn angles, i.e. systematic deviations from the correct angle that were characteristic of certain participants, whereas varying path length had weak effects on turn accuracy and precision. To check whether this idiosyncrasy was persistent over time and present in another type of walking task, we performed a second experiment several weeks after the first. Here, the same participants were guided to walk turns with varying amplitude. We then asked them to judge whether they had walked an angle larger or smaller than 90 in a two-alternative forced-choice (2AFC) paradigm. Very surprisingly, the personal bias was highly correlated between the two experiments indicating that the sense of direction can be persistently and individually biased in the absence of external directional cues. In a third experiment the participants where asked to walk straight on slanted and level surfaces. Here, we again found persistent directional biases in most participants. The direction of surface inclination did not significantly influence these individual biases. We found systematic angular biases in several walking tasks that were persistent over weeks. The biases reported here for healthy participants are most likely counterbalanced during normal daily-life by using visual and auditory cues for spatial orientation. Meeting abstract presented at VSS 2015. PMID:26327013

  2. Walk Score and Transit Score and Walking in the Multi-Ethnic Study of Atherosclerosis

    PubMed Central

    Hirsch, Jana A.; Moore, Kari A.; Evenson, Kelly R.; Rodriguez, Daniel A; Diez Roux, Ana V.

    2013-01-01

    Background Walk Score and Transit Score are open-source measures of the neighborhood built environment to support walking (walkability) and access to transportation. Purpose To investigate associations of Street Smart Walk Score and Transit Score with self-reported transport and leisure walking using data from a large multi-city and diverse population-based sample of adults. Methods Data from a sample of 4552 residents of Baltimore MD; Chicago IL; Forsyth County NC; Los Angeles CA; New York NY; and St. Paul MN from the Multi-Ethnic Study of Atherosclerosis (20102012) were linked to Walk Score and Transit Score (collected in 2012). Logistic and linear regression models estimated ORs of not walking and mean differences in minutes walked, respectively, associated with continuous and categoric Walk Score and Transit Score. All analyses were conducted in 2012. Results After adjustment for site, key sociodemographic, and health variables, a higher Walk Score was associated with lower odds of not walking for transport and more minutes/week of transport walking. Compared to those in a walkers paradise, lower categories of Walk Score were associated with a linear increase in odds of not transport walking and a decline in minutes of leisure walking. An increase in Transit Score was associated with lower odds of not transport walking or leisure walking, and additional minutes/week of leisure walking. Conclusions Walk Score and Transit Score appear to be useful as measures of walkability in analyses of neighborhood effects. PMID:23867022

  3. Mechanical design of walking machines.

    PubMed

    Arikawa, Keisuke; Hirose, Shigeo

    2007-01-15

    The performance of existing actuators, such as electric motors, is very limited, be it power-weight ratio or energy efficiency. In this paper, we discuss the method to design a practical walking machine under this severe constraint with focus on two concepts, the gravitationally decoupled actuation (GDA) and the coupled drive. The GDA decouples the driving system against the gravitational field to suppress generation of negative power and improve energy efficiency. On the other hand, the coupled drive couples the driving system to distribute the output power equally among actuators and maximize the utilization of installed actuator power. First, we depict the GDA and coupled drive in detail. Then, we present actual machines, TITAN-III and VIII, quadruped walking machines designed on the basis of the GDA, and NINJA-I and II, quadruped wall walking machines designed on the basis of the coupled drive. Finally, we discuss walking machines that travel on three-dimensional terrain (3D terrain), which includes the ground, walls and ceiling. Then, we demonstrate with computer simulation that we can selectively leverage GDA and coupled drive by walking posture control. PMID:17148055

  4. Random walks in noninteger dimension

    SciTech Connect

    Bender, C.M.; Boettcher, S. ); Mead, L.R. )

    1994-01-01

    One can define a random walk on a hypercubic lattice in a space of integer dimension [ital D]. For such a process formulas can be derived that express the probability of certain events, such as the chance of returning to the origin after a given number of time steps. These formulas are physically meaningful for integer values of [ital D]. However, these formulas are unacceptable as probabilities when continued to noninteger [ital D] because they give values that can be greater than 1 or less than 0. In this paper a different kind of random walk is proposed which gives acceptable probabilities for all real values of [ital D]. This [ital D]-dimensional random walk is defined on a rotationally symmetric geometry consisting of concentric spheres. The exact result is given for the probability of returning to the origin for all values of [ital D] in terms of the Riemann zeta function. This result has a number-theoretic interpretation.

  5. Effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force

    PubMed Central

    Park, Seung Kyu; Yang, Dae Jung; Kang, Yang Hun; Kim, Je Ho; Uhm, Yo Han; Lee, Yong Seon

    2015-01-01

    [Purpose] The purpose of this study was to investigate the effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force. [Subjects] The subjects of this study were 30 young adult males, who were divided into a Nordic walking group of 15 subjects and a walking group of 15 subjects. [Methods] To analyze the spatiotemporal parameters and ground reaction force during walking in the two groups, the six-camera Vicon MX motion analysis system was used. The subjects were asked to walk 12 meters using the more comfortable walking method for them between Nordic walking and walking. After they walked 12 meters more than 10 times, their most natural walking patterns were chosen three times and analyzed. To determine the pole for Nordic walking, each subjects height was multiplied by 0.68. We then measured the spatiotemporal gait parameters and ground reaction force. [Results] Compared with the walking group, the Nordic walking group showed an increase in cadence, stride length, and step length, and a decrease in stride time, step time, and vertical ground reaction force. [Conclusion] The results of this study indicate that Nordic walking increases the stride and can be considered as helping patients with diseases affecting their gait. This demonstrates that Nordic walking is more effective in improving functional capabilities by promoting effective energy use and reducing the lower limb load, because the weight of the upper and lower limbs is dispersed during Nordic walking. PMID:26504319

  6. Effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force.

    PubMed

    Park, Seung Kyu; Yang, Dae Jung; Kang, Yang Hun; Kim, Je Ho; Uhm, Yo Han; Lee, Yong Seon

    2015-09-01

    [Purpose] The purpose of this study was to investigate the effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force. [Subjects] The subjects of this study were 30 young adult males, who were divided into a Nordic walking group of 15 subjects and a walking group of 15 subjects. [Methods] To analyze the spatiotemporal parameters and ground reaction force during walking in the two groups, the six-camera Vicon MX motion analysis system was used. The subjects were asked to walk 12 meters using the more comfortable walking method for them between Nordic walking and walking. After they walked 12 meters more than 10 times, their most natural walking patterns were chosen three times and analyzed. To determine the pole for Nordic walking, each subject's height was multiplied by 0.68. We then measured the spatiotemporal gait parameters and ground reaction force. [Results] Compared with the walking group, the Nordic walking group showed an increase in cadence, stride length, and step length, and a decrease in stride time, step time, and vertical ground reaction force. [Conclusion] The results of this study indicate that Nordic walking increases the stride and can be considered as helping patients with diseases affecting their gait. This demonstrates that Nordic walking is more effective in improving functional capabilities by promoting effective energy use and reducing the lower limb load, because the weight of the upper and lower limbs is dispersed during Nordic walking. PMID:26504319

  7. After Talking the Talk, Now Walk the Walk

    ERIC Educational Resources Information Center

    Vukovic, Paul

    2011-01-01

    In this article, the author describes what his students are doing following the ATM Easter conference in Telford, where he was inspired by a workshop entitled "Vitamin D Maths," conducted by Jocelyn D'Arcy. He describes an activity that allows his Year 11 students to walk through angles drawn on the floors. This topic will now literally be given a

  8. After Talking the Talk, Now Walk the Walk

    ERIC Educational Resources Information Center

    Vukovic, Paul

    2011-01-01

    In this article, the author describes what his students are doing following the ATM Easter conference in Telford, where he was inspired by a workshop entitled "Vitamin D Maths," conducted by Jocelyn D'Arcy. He describes an activity that allows his Year 11 students to walk through angles drawn on the floors. This topic will now literally be given a…

  9. Whistle and Walk While You Work

    MedlinePLUS

    ... fullstory_155058.html Whistle ? and Walk ? While You Work Small study found a short stroll restored blood ... have to sit almost all day while you work, take a short walk whenever you can. Why? ...

  10. Do Exercise Walkers Need Special Walking Shoes?

    ERIC Educational Resources Information Center

    Barnes, Lan

    1987-01-01

    The emergence of exercise walking as a popular fitness activity has spurred sales of shoes designed and marketed specifically for walking. Consumers may find comfort and stability in these shoes--but certain other shoes may work as well. (Author)

  11. Dissipative quantum computing with open quantum walks

    SciTech Connect

    Sinayskiy, Ilya; Petruccione, Francesco

    2014-12-04

    An open quantum walk approach to the implementation of a dissipative quantum computing scheme is presented. The formalism is demonstrated for the example of an open quantum walk implementation of a 3 qubit quantum circuit consisting of 10 gates.

  12. KidsWalk-to-School: A Guide To Promote Walking to School.

    ERIC Educational Resources Information Center

    Center for Chronic Disease Prevention and Health Promotion (DHHS/CDC), Atlanta, GA.

    This guide encourages people to create safe walking and biking routes to school, promoting four issues: physically active travel, safe and walkable routes to school, crime prevention, and health environments. The chapters include: "KidsWalk-to-School: A Guide to Promote Walking to School" (Is there a solution? Why is walking to school important?…

  13. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 3 2013-01-01 2013-01-01 false Definitions concerning walk-in coolers and walk-in freezers. 431.302 Section 431.302 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers §...

  14. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 3 2011-01-01 2011-01-01 false Definitions concerning walk-in coolers and walk-in freezers. 431.302 Section 431.302 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers §...

  15. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 3 2012-01-01 2012-01-01 false Definitions concerning walk-in coolers and walk-in freezers. 431.302 Section 431.302 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers §...

  16. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Definitions concerning walk-in coolers and walk-in freezers. 431.302 Section 431.302 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers §...

  17. Successful Statewide Walking Program Websites

    ERIC Educational Resources Information Center

    Teran, Bianca Maria; Hongu, Nobuko

    2012-01-01

    Statewide Extension walking programs are making an effort to increase physical activity levels in America. An investigation of all 20 of these programs revealed that 14 use websites as marketing and educational tools, which could prove useful as the popularity of Internet communities continues to grow. Website usability information and an analysis

  18. Closed walks for community detection

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Sun, Peng Gang; Hu, Xia; Li, Zhou Jun

    2014-03-01

    In this paper, we propose a novel measure that integrates both the concept of closed walks and clustering coefficients to replace the edge betweenness in the well-known divisive hierarchical clustering algorithm, the Girvan and Newman method (GN). The edges with the lowest value are removed iteratively until the network is degenerated into isolated nodes. The experimental results on computer generated networks and real-world networks showed that our method makes a better tradeoff of accuracy and runtime. Based on the analysis of the results, we observe that the nontrivial closed walks of order three and four can be considered as the basic elements in constructing community structures. Meanwhile, we discover that those nontrivial closed walks outperform trivial closed walks in the task of analyzing the structure of networks. The double peak structure problem is mentioned in the last part of the article. We find that our proposed method is a novel way to solve the double peak structure problem. Our work can provide us with a new perspective for understanding community structure in complex networks.

  19. Behavior Management by Walking Around

    ERIC Educational Resources Information Center

    Boardman, Randolph M.

    2004-01-01

    An emerging concept from the field of business is to manage organizations by wandering around and engaging staff and consumers in informal interactions. The author extends these ideas to settings serving children and youth. In the best seller, In Search of Excellence, Peters and Waterman (1982) introduced Management by Walking Around (MBWA) as an

  20. Walk around the Block Curriculum.

    ERIC Educational Resources Information Center

    Center for Understanding the Built Environment, Prairie Village, KS.

    This curriculum packet contains two teacher-developed lesson plans for upper elementary students focusing on the built environment. The first lesson plan, "The Built Environment--An Integrating Theme" (Liesa Schroeder), offers suggestions for developing a walking tour around the school neighborhood, a historic area, or a city square. It finds that

  1. Listening Walks and Singing Maps

    ERIC Educational Resources Information Center

    Cardany, Audrey Berger

    2011-01-01

    The Listening Walk by Paul Showers and illustrated by Aliki, and "It's My City: A Singing Map" by April Pulley Sayre with pictures by Denis Roche, provide two examples of texts that aid in building children's phonological awareness for reading and music. The author describes each narrative and discusses its function as a springboard to composition

  2. A Leadership Walk across Gettysburg

    ERIC Educational Resources Information Center

    Millward, Robert E.

    2009-01-01

    School administrators find the Civil War battlefield an appropriate venue for fully appreciating the role of vision, mentoring and the power of words. The author, a professor at Indiana University of Pennsylvania, has organized leadership walks across Gettysburg for superintendents and principals for a decade. This article describes the

  3. Walking Tips for Older Adults

    MedlinePLUS

    ... the most ppular form of exercise among older adults and it's a great choice. What can walking do for you? strengthen muscles help prevent weight gain lower risks of heart disease, stroke, diabetes, and osteoporosis improve balance lower the likelihood of falling If it’s been ...

  4. Notes on Inhomogeneous Quantum Walks

    NASA Astrophysics Data System (ADS)

    Shikano, Yutaka; Katsura, Hosho

    2011-10-01

    We study a class of discrete-time quantum walks with inhomogeneous coins defined in [Y. Shikano and H. Katsura, Phys. Rev. E 82, 031122 (2010)]. We establish symmetry properties of the spectrum of the evolution operator, which resembles the Hofstadter butterfly.

  5. A Walk to the Well.

    ERIC Educational Resources Information Center

    Weir, Phil

    1994-01-01

    During a walk, an outdoor education teacher reflects on the status of outdoor education in Ottawa (Canada) and importance of maintaining a close relationship with nature. He looks for signs of an old log home site, observes a hawk's flight, discovers remains of a plastic bag in an owl pellet, and realizes that everyone is working on survival. (LP)

  6. Listening Walks and Singing Maps

    ERIC Educational Resources Information Center

    Cardany, Audrey Berger

    2011-01-01

    The Listening Walk by Paul Showers and illustrated by Aliki, and "It's My City: A Singing Map" by April Pulley Sayre with pictures by Denis Roche, provide two examples of texts that aid in building children's phonological awareness for reading and music. The author describes each narrative and discusses its function as a springboard to composition…

  7. Generalized Open Quantum Walks on Apollonian Networks

    PubMed Central

    Pawela, Łukasz; Gawron, Piotr; Miszczak, Jarosław Adam; Sadowski, Przemysław

    2015-01-01

    We introduce the model of generalized open quantum walks on networks using the Transition Operation Matrices formalism. We focus our analysis on the mean first passage time and the average return time in Apollonian networks. These results differ significantly from a classical walk on these networks. We show a comparison of the classical and quantum behaviour of walks on these networks. PMID:26177452

  8. The Recovery of Walking in Stroke Patients: A Review

    ERIC Educational Resources Information Center

    Jang, Sung Ho

    2010-01-01

    We reviewed the literature on walking recovery of stroke patients as it relates to the following subjects: epidemiology of walking dysfunction, recovery course of walking, and recovery mechanism of walking (neural control of normal walking, the evaluation methods for leg motor function, and motor recovery mechanism of leg). The recovery of walking

  9. 10 CFR 431.302 - Definitions concerning walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Definitions concerning walk-in coolers and walk-in freezers. 431.302 Section 431.302 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers § 431.302 Definitions concerning walk-in coolers and...

  10. To Walk or Not to Walk?: The Hierarchy of Walking Needs

    ERIC Educational Resources Information Center

    Alfonzo, Mariela

    2005-01-01

    The multitude of quality of life problems associated with declining walking rates has impelled researchers from various disciplines to identify factors related to this behavior change. Currently, this body of research is in need of a transdisciplinary, multilevel theoretical model that can help explain how individual, group, regional, and

  11. Non-backtracking Random Walk

    NASA Astrophysics Data System (ADS)

    Fitzner, Robert; van der Hofstad, Remco

    2013-01-01

    We consider non-backtracking random walk (NBW) in the nearest-neighbor setting on the ? d -lattice and on tori. We evaluate the eigensystem of the m m-dimensional transition matrix of NBW where m denote the degree of the graph. We use its eigensystem to show a functional central limit theorem for NBW on ? d and to obtain estimates on the convergence towards the stationary distribution for NBW on the torus.

  12. Segment lengths influence hill walking strategies.

    PubMed

    Sheehan, Riley C; Gottschall, Jinger S

    2014-08-22

    Segment lengths are known to influence walking kinematics and muscle activity patterns. During level walking at the same speed, taller individuals take longer, slower strides than shorter individuals. Based on this, we sought to determine if segment lengths also influenced hill walking strategies. We hypothesized that individuals with longer segments would display more joint flexion going uphill and more extension going downhill as well as greater lateral gastrocnemius and vastus lateralis activity in both directions. Twenty young adults of varying heights (below 155 cm to above 188 cm) walked at 1.25 m/s on a level treadmill as well as 6 and 12 up and downhill slopes while we collected kinematic and muscle activity data. Subsequently, we ran linear regressions for each of the variables with height, leg, thigh, and shank length. Despite our population having twice the anthropometric variability, the level and hill walking patterns matched closely with previous studies. While there were significant differences between level and hill walking, there were few hill walking variables that were correlated with segment length. In support of our hypothesis, taller individuals had greater knee and ankle flexion during uphill walking. However, the majority of the correlations were between tibialis anterior and lateral gastrocnemius activities and shank length. Contrary to our hypothesis, relative step length and muscle activity decreased with segment length, specifically shank length. In summary, it appears that individuals with shorter segments require greater propulsion and toe clearance during uphill walking as well as greater braking and stability during downhill walking. PMID:24968942

  13. Positive messaging promotes walking in older adults

    PubMed Central

    Notthoff, Nanna; Carstensen, Laura L.

    2014-01-01

    Walking is among the most cost-effective and accessible means of exercise. Mounting evidence suggests that walking may help to maintain physical and cognitive independence in old age by preventing a variety of health problems. However, older Americans fall far short of meeting the daily recommendations for walking. In two studies, we examined whether considering older adults preferential attention to positive information may effectively enhance interventions aimed at promoting walking. In Study 1, we compared the effectiveness of positive, negative, and neutral messages to encourage walking (as measured with pedometers). Older adults who were informed about the benefits of walking walked more than those who were informed about the negative consequences of failing to walk, whereas younger adults were unaffected by framing valence. In Study 2, we examined within-person change in walking in older adults in response to positively- or negatively-framed messages over a 28-day period. Once again, positively-framed messages more effectively promoted walking than negatively-framed messages, and the effect was sustained across the intervention period. Together, these studies suggest that consideration of age-related changes in preferences for positive and negative information may inform the design of effective interventions to promote healthy lifestyles. Future research is needed to examine the mechanisms underlying the greater effectiveness of positively as opposed to negatively framed messages and the generalizability of findings to other intervention targets and other subpopulations of older adults. PMID:24956001

  14. Positive messaging promotes walking in older adults.

    PubMed

    Notthoff, Nanna; Carstensen, Laura L

    2014-06-01

    Walking is among the most cost-effective and accessible means of exercise. Mounting evidence suggests that walking may help to maintain physical and cognitive independence in old age by preventing a variety of health problems. However, older Americans fall far short of meeting the daily recommendations for walking. In 2 studies, we examined whether considering older adults' preferential attention to positive information may effectively enhance interventions aimed at promoting walking. In Study 1, we compared the effectiveness of positive, negative, and neutral messages to encourage walking (as measured with pedometers). Older adults who were informed about the benefits of walking walked more than those who were informed about the negative consequences of failing to walk, whereas younger adults were unaffected by framing valence. In Study 2, we examined within-person change in walking in older adults in response to positively- or negatively-framed messages over a 28-day period. Once again, positively-framed messages more effectively promoted walking than negatively-framed messages, and the effect was sustained across the intervention period. Together, these studies suggest that consideration of age-related changes in preferences for positive and negative information may inform the design of effective interventions to promote healthy lifestyles. Future research is needed to examine the mechanisms underlying the greater effectiveness of positively- as opposed to negatively-framed messages and the generalizability of findings to other intervention targets and other subpopulations of older adults. PMID:24956001

  15. Differences in Walking Pattern during 6-Min Walk Test between Patients with COPD and Healthy Subjects

    PubMed Central

    Annegarn, Janneke; Spruit, Martijn A.; Savelberg, Hans H. C. M.; Willems, Paul J. B.; van Bool, Coby; Schols, Annemie M. W. J.; Wouters, Emiel F. M.; Meijer, Kenneth

    2012-01-01

    Background To date, detailed analyses of walking patterns using accelerometers during the 6-min walk test (6MWT) have not been performed in patients with chronic obstructive pulmonary disease (COPD). Therefore, it remains unclear whether and to what extent COPD patients have an altered walking pattern during the 6MWT compared to healthy elderly subjects. Methodology/Principal Findings 79 COPD patients and 24 healthy elderly subjects performed the 6MWT wearing an accelerometer attached to the trunk. The accelerometer features (walking intensity, cadence, and walking variability) and subject characteristics were assessed and compared between groups. Moreover, associations were sought with 6-min walk distance (6MWD) using multiple ordinary least squares (OLS) regression models. COPD patients walked with a significantly lower walking intensity, lower cadence and increased walking variability compared to healthy subjects. Walking intensity and height were the only two significant determinants of 6MWD in healthy subjects, explaining 85% of the variance in 6MWD. In COPD patients also age, cadence, walking variability measures and their interactions were included were significant determinants of 6MWD (total variance in 6MWD explained: 88%). Conclusions/Significance COPD patients have an altered walking pattern during 6MWT compared to healthy subjects. These differences in walking pattern partially explain the lower 6MWD in patients with COPD. PMID:22624017

  16. Walk-Startup of a Two-Legged Walking Mechanism

    NASA Astrophysics Data System (ADS)

    Babkovi?, Kalman; Nagy, Lszl; Krklje, Damir; Borovac, Branislav

    There is a growing interest towards humanoid robots. One of their most important characteristic is the two-legged motion - walk. Starting and stopping of humanoid robots introduce substantial delays. In this paper, the goal is to explore the possibility of using a short unbalanced state of the biped robot to quickly gain speed and achieve the steady state velocity during a period shorter than half of the single support phase. The proposed method is verified by simulation. Maintainig a steady state, balanced gait is not considered in this paper.

  17. Quantum walks with random phase shifts

    SciTech Connect

    Kosik, Jozef; Buzek, Vladimir; Hillery, Mark

    2006-08-15

    We investigate quantum walks in multiple dimensions with different quantum coins. We augment the model by assuming that at each step the amplitudes of the coin state are multiplied by random phases. This model enables us to study in detail the role of decoherence in quantum walks and to investigate the quantum-to-classical transition. We also provide classical analog of the quantum random walks studied. Interestingly enough, it turns out that the classical counterparts of some quantum random walks are classical random walks with a memory and biased coin. In addition random phase shifts 'simplify' the dynamics (the cross-interference terms of different paths vanish on average) and enable us to give a compact formula for the dispersion of such walks.

  18. Quantum walks driven by many coins

    SciTech Connect

    Brun, Todd A.; Ambainis, Andris; Carteret, Hilary A.

    2003-05-01

    Quantum random walks have been much studied recently, largely due to their highly nonclassical behavior. In this paper, we study one possible route to classical behavior for the discrete quantum random walk on the line: the use of multiple quantum 'coins' (or more generally, coins of higher dimension) in order to diminish the effects of interference between paths. We find solutions to this system in terms of the single-coin random walk, and compare the asymptotic limit of these solutions to numerical simulations. We find exact analytical expressions for the time dependence of the first two moments, and show that in the long-time limit the ''quantum-mechanical'' behavior of the one-coin walk persists, even if each coin is flipped only twice. We further show that this is generic for a very broad class of possible walks, and that this behavior disappears only in the limit of a new coin for every step of the walk.

  19. Lvy Walks Suboptimal under Predation Risk

    PubMed Central

    Abe, Masato S.; Shimada, Masakazu

    2015-01-01

    A key challenge in movement ecology is to understand how animals move in nature. Previous studies have predicted that animals should perform a special class of random walks, called Lvy walk, to obtain more targets. However, some empirical studies did not support this hypothesis, and the relationship between search strategy and ecological factors is still unclear. We focused on ecological factors, such as predation risk, and analyzed whether Lvy walk may not be favored. It was remarkable that the ecological factors often altered an optimal search strategy from Lvy walk to Brownian walk, depending on the speed of the predators movement, density of predators, etc. This occurred because higher target encounter rates simultaneously led searchers to higher predation risks. Our findings indicate that animals may not perform Lvy walks often, and we suggest that it is crucial to consider the ecological context for evaluating the search strategy performed by animals in the field. PMID:26544687

  20. Continuous limit of discrete quantum walks

    NASA Astrophysics Data System (ADS)

    M N, Dheeraj; Brun, Todd A.

    2015-06-01

    Quantum walks can be defined in two quite distinct ways: discrete-time and continuous-time quantum walks (DTQWs and CTQWs). For classical random walks, there is a natural sense in which continuous-time walks are a limit of discrete-time walks. Quantum mechanically, in the discrete-time case, an additional "coin space" must be appended for the walk to have nontrivial time evolution. Continuous-time quantum walks, however, have no such constraints. This means that there is no completely straightforward way to treat a CTQW as a limit of a DTQW, as can be done in the classical case. Various approaches to this problem have been taken in the past. We give a construction for walks on d -regular, d -colorable graphs when the coin flip operator is Hermitian: from a standard DTQW we construct a family of discrete-time walks with a well-defined continuous-time limit on a related graph. One can think of this limit as a "coined" continuous-time walk. We show that these CTQWs share some properties with coined DTQWs. In particular, we look at a spatial search by a DTQW over the two-dimensional (2D) torus (a grid with periodic boundary conditions) of size ?{N }?{N } , where it was shown that a coined DTQW can search in time O (?{N }logN ) , but a standard CTQW takes ? (N ) time to search for a marked element. The continuous limit of the DTQW search over the 2D torus exhibits the O (?{N }logN ) scaling, like the coined walk it is derived from. We also look at the effects of graph symmetry on the limiting walk, and show that the properties are similar to those of the DTQW as shown in Krovi and Brun, Phys. Rev. A 75, 062332 (2007), 10.1103/PhysRevA.75.062332.

  1. Gaitography applied to prosthetic walking.

    PubMed

    Roerdink, Melvyn; Cutti, Andrea G; Summa, Aurora; Monari, Davide; Veronesi, Davide; van Ooijen, Marille W; Beek, Peter J

    2014-11-01

    During walking on an instrumented treadmill with an embedded force platform or grid of pressure sensors, center-of-pressure (COP) trajectories exhibit a characteristic butterfly-like shape, reflecting the medio-lateral and anterior-posterior weight shifts associated with alternating steps. We define "gaitography" as the analysis of such COP trajectories during walking (the "gaitograms"). It is currently unknown, however, if gaitography can be employed to characterize pathological gait, such as lateralized gait impairments. We therefore registered gaitograms for a heterogeneous sample of persons with a trans-femoral and trans-tibial amputation during treadmill walking at a self-selected comfortable speed. We found that gaitograms directly visualize between-person differences in prosthetic gait in terms of step width and the relative duration of prosthetic and non-prosthetic single-support stance phases. We further demonstrated that one should not only focus on the gaitogram's shape but also on the time evolution along that shape, given that the COP evolves much slower in the single-support phase than in the double-support phase. Finally, commonly used temporal and spatial prosthetic gait characteristics were derived, revealing both individual and systematic differences in prosthetic and non-prosthetic step lengths, step times, swing times, and double-support durations. Because gaitograms can be rapidly collected in an unobtrusive and markerless manner over multiple gait cycles without constraining foot placement, clinical application of gaitography seems both expedient and appealing. Studies examining the repeatability of gaitograms and evaluating gaitography-based gait characteristics against a gold standard with known validity and reliability are required before gaitography can be clinically applied. PMID:25249276

  2. Efficient quantum circuit implementation of quantum walks

    SciTech Connect

    Douglas, B. L.; Wang, J. B.

    2009-05-15

    Quantum walks, being the quantum analog of classical random walks, are expected to provide a fruitful source of quantum algorithms. A few such algorithms have already been developed, including the 'glued trees' algorithm, which provides an exponential speedup over classical methods, relative to a particular quantum oracle. Here, we discuss the possibility of a quantum walk algorithm yielding such an exponential speedup over possible classical algorithms, without the use of an oracle. We provide examples of some highly symmetric graphs on which efficient quantum circuits implementing quantum walks can be constructed and discuss potential applications to quantum search for marked vertices along these graphs.

  3. Random walks between leaves of random networks

    NASA Astrophysics Data System (ADS)

    Lancaster, David

    2014-02-01

    Motivated by the desire to model internet traffic we consider random walks that start and are absorbed on the leaves of random networks and study the length of such walks. We present and test two techniques to analyse these walks. On Erd?s-Rnyi random graphs where the probability of a walk decays exponentially with its length, the methods give indistinguishable results for the decay exponent. This simple form of decay is not apparent on heterogeneous networks such as Barabsi-Albert scale free networks and in this case each technique is demonstrated to have a different strength.

  4. Walking-age analyzer for healthcare applications.

    PubMed

    Jin, Bo; Thu, Tran Hoai; Baek, Eunhye; Sakong, SungHwan; Xiao, Jin; Mondal, Tapas; Deen, M Jamal

    2014-05-01

    This paper describes a walking-age pattern analysis and identification system using a 3-D accelerometer and a gyroscope. First, a walking pattern database from 79 volunteers of ages ranging from 10 to 83 years is constructed. Second, using feature extraction and clustering, three distinct walking-age groups, children of ages 10 and below, adults in 20-60s, and elders in 70s and 80s, were identified. For this study, low-pass filtering, empirical mode decomposition, and K-means were used to process and analyze the experimental results. Analysis shows that volunteers' walking-ages can be categorized into distinct groups based on simple walking pattern signals. This grouping can then be used to detect persons with walking patterns outside their age groups. If the walking pattern puts an individual in a higher "walking age" grouping, then this could be an indicator of potential health/walking problems, such as weak joints, poor musculoskeletal support system or a tendency to fall. PMID:24808231

  5. Visual Acuity During Treadmill Walking

    NASA Technical Reports Server (NTRS)

    Peters, B. T.; Brady, R.; vanEmmerik, R. E. A.; Bloomberg, Jacob J.

    2006-01-01

    An awareness of the physical world is essential for successful navigation through the environment. Vision is the means by which this awareness is made possible for most people. However, without adequate compensation, the movements of the body during walking could impair vision. Previous research has shown how the eyes, head and trunk movements are coordinated to provide the compensation necessary for clear vision, but the overall effectiveness of these coordinated movements is unknown. The goal of the research presented here was to provide a direct measure of visual performance during locomotion, while also investigating the degree to which coordinated head and body movements can be altered to facilitate the goal of seeing clearly.

  6. Quantum walks with encrypted data.

    PubMed

    Rohde, Peter P; Fitzsimons, Joseph F; Gilchrist, Alexei

    2012-10-12

    In the setting of networked computation, data security can be a significant concern. Here we consider the problem of allowing a server to remotely manipulate client supplied data, in such a way that both the information obtained by the client about the server's operation and the information obtained by the server about the client's data are significantly limited. We present a protocol for achieving such functionality in two closely related models of restricted quantum computation-the boson sampling and quantum walk models. Because of the limited technological requirements of the boson scattering model, small scale implementations of this technique are feasible with present-day technology. PMID:23102287

  7. Walking Performance: Correlation between Energy Cost of Walking and Walking Participation. New Statistical Approach Concerning Outcome Measurement

    PubMed Central

    Franceschini, Marco; Rampello, Anais; Agosti, Maurizio; Massucci, Maurizio; Bovolenta, Federica; Sale, Patrizio

    2013-01-01

    Walking ability, though important for quality of life and participation in social and economic activities, can be adversely affected by neurological disorders, such as Spinal Cord Injury, Stroke, Multiple Sclerosis or Traumatic Brain Injury. The aim of this study is to evaluate if the energy cost of walking (CW), in a mixed group of chronic patients with neurological diseases almost 6 months after discharge from rehabilitation wards, can predict the walking performance and any walking restriction on community activities, as indicated by Walking Handicap Scale categories (WHS). One hundred and seven subjects were included in the study, 31 suffering from Stroke, 26 from Spinal Cord Injury and 50 from Multiple Sclerosis. The multivariable binary logistical regression analysis has produced a statistical model with good characteristics of fit and good predictability. This model generated a cut-off value of.40, which enabled us to classify correctly the cases with a percentage of 85.0%. Our research reveal that, in our subjects, CW is the only predictor of the walking performance of in the community, to be compared with the score of WHS. We have been also identifying a cut-off value of CW cost, which makes a distinction between those who can walk in the community and those who cannot do it. In particular, these values could be used to predict the ability to walk in the community when discharged from the rehabilitation units, and to adjust the rehabilitative treatment to improve the performance. PMID:23468871

  8. Walking performance: correlation between energy cost of walking and walking participation. new statistical approach concerning outcome measurement.

    PubMed

    Franceschini, Marco; Rampello, Anais; Agosti, Maurizio; Massucci, Maurizio; Bovolenta, Federica; Sale, Patrizio

    2013-01-01

    Walking ability, though important for quality of life and participation in social and economic activities, can be adversely affected by neurological disorders, such as Spinal Cord Injury, Stroke, Multiple Sclerosis or Traumatic Brain Injury. The aim of this study is to evaluate if the energy cost of walking (CW), in a mixed group of chronic patients with neurological diseases almost 6 months after discharge from rehabilitation wards, can predict the walking performance and any walking restriction on community activities, as indicated by Walking Handicap Scale categories (WHS). One hundred and seven subjects were included in the study, 31 suffering from Stroke, 26 from Spinal Cord Injury and 50 from Multiple Sclerosis. The multivariable binary logistical regression analysis has produced a statistical model with good characteristics of fit and good predictability. This model generated a cut-off value of.40, which enabled us to classify correctly the cases with a percentage of 85.0%. Our research reveal that, in our subjects, CW is the only predictor of the walking performance of in the community, to be compared with the score of WHS. We have been also identifying a cut-off value of CW cost, which makes a distinction between those who can walk in the community and those who cannot do it. In particular, these values could be used to predict the ability to walk in the community when discharged from the rehabilitation units, and to adjust the rehabilitative treatment to improve the performance. PMID:23468871

  9. Walking activities and wear of prostheses.

    PubMed Central

    Seedhom, B B; Wallbridge, N C

    1985-01-01

    A study of the walking activities of 243 individuals was carried out. The individuals came from four different occupations and had an age range of 17-83 years. The survey carried out in this investigation showed surprisingly little correlation between variables such as age, height, and weight of individuals and their speed of walking, length of stride, or distance walked. Correlation matrices were obtained for the whole sample and then for each sex, showing similar trends. The most significant correlation was between the height of an individual and the length of the stride, and there was a lesser correlation between age and the number of steps walked by an individual per day. Further statistical analyses showed that males in manual occupations walked most and those in sedentary occupations walked least. On the other hand, in the female groups housewives seemed to walk least and those in technical occupations walked most. The average number of steps walked per day by a male individual for the whole sample was 9537; that for females was 9839. The corresponding distances walked per day were 6.7 and 6.5 km. The differences were not statistically significant. Predictions of wear of prosthetic components made of ultrahigh molecular weight polyethylene were made on the basis of the above data and other variables affecting wear, such as the weight of the subject and the area available for contact during walking. Charts have been constructed of the penetration of the metallic component into the plastic one for both hip knee prostheses, thus enabling predictions of the wear of the plastic components of these two most widely used prostheses. Owing to the wide ranging values of the variables used in making the predictions of wear, these latter should be regarded only as 'safe' first estimates. PMID:4083940

  10. Walking on potential energy surfaces

    NASA Astrophysics Data System (ADS)

    Nichols, Jeff; Taylor, Hugh; Schmidt, Peter; Simons, Jack

    1990-01-01

    An algorithm for locating stationary points corresponding to local minima and transition states on potential energy surfaces is developed and analyzed. This method, which represents a substantial extension of an earlier algorithm, utilizes local gradient and Hessian (i.e., first and second energy derivative) information to generate a series of ``steps'' that are followed to the desired stationary point. By designing the step sequence to move energetically downhill in all coordinates, local minima can be found. By stepping uphill along one local eigenmode of the Hessian while minimizing the energy along all other modes, one locates transition states. A key element of this development is a more efficient parametrization of the step vector in terms of quantities that permit the direction (i.e., uphill or downhill) and length of the step to be carefully controlled. This, in turn, allows ``walks'' that trace streambeds connecting local minima to transition states and to neighboring local minima more closely than has been found using the earlier methods. Such streambed walks provide information that can be used in subsequent reaction-path dynamics simulations.

  11. Interface Reconstruction with Directional Walking

    SciTech Connect

    Yao, J

    2009-05-22

    Young's interface reconstruction with three-dimensional arbitrary mesh, in general, is rather tedious to implement compared to the case of a regular mesh. The main difficulty comes from the construction of a planar facet that bounds a certain volume inside a cell. Unlike the five basic configurations with a Cartesian mesh, there can be a great number of different configurations in the case of a general mesh. We represent a simple method that can derive the topology/geometry of the intersection of arbitrary planar objects in a uniform way. The method is based on a directional walking on the surface of objects, and links the intersection points with the paths of the walking naturally defining the intersection of objects. The method works in both two and three dimensions. The method does not take advantage of convexity, thus decomposition of an object is not necessary. Therefore, the solution with this method will have a reduced number of edges and less data storage, compared with methods that use shape decomposition. The treatment is general for arbitrary polyhedrons, and no look-up tables are needed. The same operation can easily be extended for curved geometry. The implementation of this new algorithm shall allow the interface reconstruction on an arbitrary mesh to be as simple as it is on a regular mesh. Furthermore, we exactly compute the integral of partial cell volume bounded by quadratic interface. Therefore, interface reconstruction with higher than second order accuracy can be achieved on an arbitrary mesh.

  12. Comparison of Walking with Poles and Traditional Walking for Peripheral Arterial Disease Rehabilitation

    PubMed Central

    Collins, Eileen G.; OConnell, Susan; McBurney, Conor; Jelinek, Christine; Butler, Jolene; Reda, Domenic; Gerber, Ben S.; Hurt, Christopher; Grabiner, Mark

    2012-01-01

    PURPOSE The purpose of this study was to compare the effects of a 24-week walking with poles rehabilitation program with a traditional 24-week walking program on physical function in patients with peripheral arterial disease (PAD). METHODS Patients with PAD (n=103, age = 69.78.9 years, ankle-brachial index <0.90 or evidence of calcified vessels) were randomized into a rehabilitation program of traditional walking (n=52) or walking with poles (n=51). Patients exercised 3 times per week for 24 weeks. Exercise endurance was measured by time walked on a constant workrate treadmill test at 6, 12, and 24 weeks. Perceived physical function was measured by the SF-36 and Walking Impairment Questionnaire. Tissue oxygenation was measured using near-infrared spectroscopy. RESULTS Patients assigned to the traditional walking group walked longer at 24 weeks than those assigned to the pole walking group (21.1017.07 min and 15.0212.32 respectively, P=.037). There were no differences between the groups in tissue oxygenation. However, there was a significant lengthening of time for which it took to reach minimum tissue oxygenation values (P <0.001) within the groups on the constant workrate test. There were no differences between the groups in perceived physical function as measured by the physical function subscale on the Short-Form 36 or perceived walking distance as measured by the walking distance subscale on the Walking Impairment Scale. CONCLUSIONS Traditional walking was superior to walking with poles in increasing walking endurance on a constant workrate treadmill test for patients with peripheral arterial disease. PMID:22595894

  13. Web-Based Walk-Throughs

    ERIC Educational Resources Information Center

    Granada, Janet; Vriesenga, Michael

    2008-01-01

    Walk-through classroom observations are an effective way for principals to learn about and shape instruction and culture in their schools. But many principals don't use walk-throughs to their potential because of the time it takes to store, process, analyze, and give feedback. To facilitate the use of this valuable observation tool, the Kentucky

  14. Southern women's response to a walking intervention.

    PubMed

    Nies, Mary A; Reisenberg, Catherine E; Chruscial, Heather L; Artibee, Kay

    2003-01-01

    The need to change the sedentary habits of many American adults is well recognized. Middle-aged women are an important target group for increased physical activity because of certain health risks such as osteoporosis. In the current study, 31 women between the ages of 30 and 60 from high- and low-income groups (high-income >$50,000; low-income <$50,000 per year) took part in a physical activity intervention. The goal was to increase walking activity to a minimum of 90 min per week. Each woman received 16 telephone calls over a 6-month period in which she was asked to reflect upon the benefits of walking, goal setting, restructuring plans, social support, exercise efficacy, relapse prevention, and maintenance. Content analysis revealed a number of themes emerging from intervention conversations. There were differences between races in walking location and walking partners. Furthermore, there were differences between income groups in beliefs about the benefits of walking and social support. Overall, the intervention appeared to provide a basis for women to develop a walking routine. The women were able to reflect upon their walking routine and attempts to begin a walking routine and to identify how each component of the intervention affected their individual daily routine. PMID:12588431

  15. Welly-Walks for Science Learning

    ERIC Educational Resources Information Center

    Fradley, Carol

    2006-01-01

    This article discusses how a regular walk in the wind or the rain can help develop science knowledge and skills. The author describes one "welly-walk" and links it to National Curriculum for England requirements so that readers can see how easy it is. (Contains 1 figure and 1 box.)

  16. Walking in circles: a modelling approach.

    PubMed

    Maus, Horst-Moritz; Seyfarth, Andre

    2014-10-01

    Blindfolded or disoriented people have the tendency to walk in circles rather than on a straight line even if they wanted to. Here, we use a minimalistic walking model to examine this phenomenon. The bipedal spring-loaded inverted pendulum exhibits asymptotically stable gaits with centre of mass (CoM) dynamics and ground reaction forces similar to human walking in the sagittal plane. We extend this model into three dimensions, and show that stable walking patterns persist if the leg is aligned with respect to the body (here: CoM velocity) instead of a world reference frame. Further, we demonstrate that asymmetric leg configurations, which are common in humans, will typically lead to walking in circles. The diameter of these circles depends strongly on parameter configuration, but is in line with empirical data from human walkers. Simulation results suggest that walking radius and especially direction of rotation are highly dependent on leg configuration and walking velocity, which explains inconsistent veering behaviour in repeated trials in human data. Finally, we discuss the relation between findings in the model and implications for human walking. PMID:25056215

  17. Interventions to Improve Walking in Older Adults

    PubMed Central

    Brach, Jennifer S.; VanSwearingen, Jessie M.

    2013-01-01

    Interventions to improve walking in older adults have historically been multifactorial (i.e. strengthening, endurance and flexibility programs) focusing on improving the underlying impairments. These impairment-based programs have resulted in only modest improvements in walking. In older adults, walking is slow, less stable, inefficient, and the timing and coordination of stepping with postures and phases of gait is poor. We argue the timing and coordination problems are evidence of the loss of motor skill in walking. Taking a lesson from the sports world and from neurorehabilitation, task-oriented motor learning exercise is an essential component of training to improve motor skill and may be a beneficial approach to improving walking in older adults. In this article we: 1) briefly review the current literature regarding impairment-based interventions for improving mobility, 2) discuss why the results have been only modest, and 3) suggest an alternative approach to intervention (i.e. task oriented motor learning). PMID:24319641

  18. Go naked: diapers affect infant walking.

    PubMed

    Cole, Whitney G; Lingeman, Jesse M; Adolph, Karen E

    2012-11-01

    In light of cross-cultural and experimental research highlighting effects of childrearing practices on infant motor skill, we asked whether wearing diapers, a seemingly innocuous childrearing practice, affects infant walking. Diapers introduce bulk between the legs, potentially exacerbating infants' poor balance and wide stance. We show that walking is adversely affected by old-fashioned cloth diapers, and that even modern disposable diapers - habitually worn by most infants in the sample - incur a cost relative to walking naked. Infants displayed less mature gait patterns and more missteps and falls while wearing diapers. Thus, infants' own diapers constitute an ongoing biomechanical perturbation while learning to walk. Furthermore, shifts in diapering practices may have contributed to historical and cross-cultural differences in infant walking. PMID:23106732

  19. Gait attentional load at different walking speeds.

    PubMed

    Nascimbeni, Alberto; Minchillo, Marco; Salatino, Adriana; Morabito, Ursula; Ricci, Raffaella

    2015-01-01

    Gait is an attention-demanding task even in healthy young adults. However, scant evidence exists about the attentional load required at various walking speeds. The aim of this study was to investigate motor-cognitive interference while walking at spontaneous, slow and very slow speed on a treadmill while carrying out a backward counting task, in a group (n = 22) of healthy young participants. Cognitive performance was also assessed while sitting. Higher DT cost on the cognitive task was found at spontaneous and very slow walking speed, while at slow walking speed the cognitive task was prioritized with higher DT cost on the motor task. The attentional allocation during DT depends on walking speed with gait prioritization at spontaneous and very slow speed that likely represent more challenging motor conditions. PMID:25270327

  20. The staggered quantum walk model

    NASA Astrophysics Data System (ADS)

    Portugal, R.; Santos, R. A. M.; Fernandes, T. D.; Gonalves, D. N.

    2016-01-01

    There are at least three models of discrete-time quantum walks (QWs) on graphs currently under active development. In this work, we focus on the equivalence of two of them, known as Szegedy's and staggered QWs. We give a formal definition of the staggered model and discuss generalized versions for searching marked vertices. Using this formal definition, we prove that any instance of Szegedy's model is equivalent to an instance of the staggered model. On the other hand, we show that there are instances of the staggered model that cannot be cast into Szegedy's framework. Our analysis also works when there are marked vertices. We show that Szegedy's spatial search algorithms can be converted into search algorithms in staggered QWs. We take advantage of the similarity of those models to define the quantum hitting time in the staggered model and to describe a method to calculate the eigenvalues and eigenvectors of the evolution operator of staggered QWs.

  1. The staggered quantum walk model

    NASA Astrophysics Data System (ADS)

    Portugal, R.; Santos, R. A. M.; Fernandes, T. D.; Gonalves, D. N.

    2015-10-01

    There are at least three models of discrete-time quantum walks (QWs) on graphs currently under active development. In this work, we focus on the equivalence of two of them, known as Szegedy's and staggered QWs. We give a formal definition of the staggered model and discuss generalized versions for searching marked vertices. Using this formal definition, we prove that any instance of Szegedy's model is equivalent to an instance of the staggered model. On the other hand, we show that there are instances of the staggered model that cannot be cast into Szegedy's framework. Our analysis also works when there are marked vertices. We show that Szegedy's spatial search algorithms can be converted into search algorithms in staggered QWs. We take advantage of the similarity of those models to define the quantum hitting time in the staggered model and to describe a method to calculate the eigenvalues and eigenvectors of the evolution operator of staggered QWs.

  2. Quantum search with multiple walk steps per oracle query

    NASA Astrophysics Data System (ADS)

    Wong, Thomas G.; Ambainis, Andris

    2015-08-01

    We identify a key difference between quantum search by discrete- and continuous-time quantum walks: a discrete-time walk typically performs one walk step per oracle query, whereas a continuous-time walk can effectively perform multiple walk steps per query while only counting query time. As a result, we show that continuous-time quantum walks can outperform their discrete-time counterparts, even though both achieve quadratic speedups over their corresponding classical random walks. To provide greater equity, we allow the discrete-time quantum walk to also take multiple walk steps per oracle query while only counting queries. Then it matches the continuous-time algorithm's runtime, but such that it is a cubic speedup over its corresponding classical random walk. This yields a greater-than-quadratic speedup for quantum search over its corresponding classical random walk.

  3. Effects of a Flexibility and Relaxation Programme, Walking, and Nordic Walking on Parkinson's Disease

    PubMed Central

    Reuter, I.; Mehnert, S.; Leone, P.; Kaps, M.; Oechsner, M.; Engelhardt, M.

    2011-01-01

    Symptoms of Parkinson's disease (PD) progress despite optimized medical treatment. The present study investigated the effects of a flexibility and relaxation programme, walking, and Nordic walking (NW) on walking speed, stride length, stride length variability, Parkinson-specific disability (UPDRS), and health-related quality of life (PDQ 39). 90 PD patients were randomly allocated to the 3 treatment groups. Patients participated in a 6-month study with 3 exercise sessions per week, each lasting 70?min. Assessment after completion of the training showed that pain was reduced in all groups, and balance and health-related quality of life were improved. Furthermore, walking, and Nordic walking improved stride length, gait variability, maximal walking speed, exercise capacity at submaximal level, and PD disease-specific disability on the UPDRS in addition. Nordic walking was superior to the flexibility and relaxation programme and walking in improving postural stability, stride length, gait pattern and gait variability. No significant injuries occurred during the training. All patients of the Nordic walking group continued Nordic walking after completing the study. PMID:21603199

  4. Downhill walking induces rapid shallow breathing.

    PubMed

    Dean, E; Ross, J

    1989-12-01

    To examine the effect of downhill walking a form of negative work on ventilation, we studied the exercise responses of 13 healthy subjects during uphill and downhill walking on a treadmill. Each test lasted 16 min and the peak work rate was 5.6 kph with either a positive or negative 14% grade. Throughout each test we recorded VO2, VE, f, VT, HR, systolic BP and Borg's rating of perceived exertion. At the target work rates of 5.6 kph +/- 14% grade, VO2 and VE were three times greater in uphill compared with downhill walking. However, in downhill walking, f was greater compared with uphill walking wherein VT approximated baseline values, reflecting rapid shallow breathing, and VT appeared to increase after reaching some critically-low level. These trends persisted when VO2 was held constant (p less than 0.01). HR and systolic BP increased and decreased with the positive and negative grade respectively. At a constant VO2 however, HR was significantly higher during downhill compared with horizontal walking (p less than 0.01) whereas systolic BP was not significantly different (p greater than 0.05). We conclude that there is a significant difference in the ventilatory responses between the two types of work performed on a treadmill. Specifically, downhill walking is associated with rapid shallow breathing which may be countered by a protective feedback mechanism at critically-low levels of VT. PMID:2622762

  5. A random walk approach to quantum algorithms.

    PubMed

    Kendon, Vivien M

    2006-12-15

    The development of quantum algorithms based on quantum versions of random walks is placed in the context of the emerging field of quantum computing. Constructing a suitable quantum version of a random walk is not trivial; pure quantum dynamics is deterministic, so randomness only enters during the measurement phase, i.e. when converting the quantum information into classical information. The outcome of a quantum random walk is very different from the corresponding classical random walk owing to the interference between the different possible paths. The upshot is that quantum walkers find themselves further from their starting point than a classical walker on average, and this forms the basis of a quantum speed up, which can be exploited to solve problems faster. Surprisingly, the effect of making the walk slightly less than perfectly quantum can optimize the properties of the quantum walk for algorithmic applications. Looking to the future, even with a small quantum computer available, the development of quantum walk algorithms might proceed more rapidly than it has, especially for solving real problems. PMID:17090467

  6. One-dimensional coinless quantum walks

    NASA Astrophysics Data System (ADS)

    Portugal, Renato; Boettcher, Stefan; Falkner, Stefan

    2015-05-01

    A coinless, discrete-time quantum walk possesses a Hilbert space whose dimension is smaller compared to the widely studied coined walk. Coined walks require the direct product of the site basis with the coin space; coinless walks operate purely in the site basis, which is clearly minimal. These coinless quantum walks have received considerable attention recently because they have evolution operators that can be obtained by a graphical method based on lattice tessellations and they have been shown to be as efficient as the best known coined walks when used as a quantum search algorithm. We argue that both formulations in their most general form are equivalent. In particular, we demonstrate how to transform the one-dimensional version of the coinless quantum walk into an equivalent extended coined version for a specific family of evolution operators. We present some of its basic, asymptotic features for the one-dimensional lattice with some examples of tessellations, and analyze the mixing time and limiting probability distributions on cycles.

  7. Built Environment Correlates of Walking: A Review

    PubMed Central

    Saelens, Brian E.; Handy, Susan L.

    2010-01-01

    Introduction The past decade has seen a dramatic increase in the empirical investigation into the relations between built environmental and physical activity. To create places that facilitate and encourage walking, practitioners need an understanding of the specific characteristics of the built environment that correlate most strongly with walking. This paper reviews evidence on the built environment correlates with walking. Method Included in this review were 13 reviews published between 2002 and 2006 and 29 original studies published in 2005 and up through May 2006. Results were summarized based on specific characteristics of the built environment and transportation walking versus recreational walking. Results Previous reviews and newer studies document consistent positive relations between walking for transportation and density, distance to non-residential destinations, and land use mix; findings for route/network connectivity, parks and open space, and personal safety are more equivocal. Results regarding recreational walking were less clear. Conclusions More recent evidence supports the conclusions of prior reviews, and new studies address some of the limitations of earlier studies. Although prospective studies are needed, evidence on correlates appears sufficient to support policy changes. PMID:18562973

  8. Walking dreams in congenital and acquired paraplegia.

    PubMed

    Saurat, Marie-Thérèse; Agbakou, Maité; Attigui, Patricia; Golmard, Jean-Louis; Arnulf, Isabelle

    2011-12-01

    To test if dreams contain remote or never-experienced motor skills, we collected during 6 weeks dream reports from 15 paraplegics and 15 healthy subjects. In 9/10 subjects with spinal cord injury and in 5/5 with congenital paraplegia, voluntary leg movements were reported during dream, including feelings of walking (46%), running (8.6%), dancing (8%), standing up (6.3%), bicycling (6.3%), and practicing sports (skiing, playing basketball, swimming). Paraplegia patients experienced walking dreams (38.2%) just as often as controls (28.7%). There was no correlation between the frequency of walking dreams and the duration of paraplegia. In contrast, patients were rarely paraplegic in dreams. Subjects who had never walked or stopped walking 4-64 years prior to this study still experience walking in their dreams, suggesting that a cerebral walking program, either genetic or more probably developed via mirror neurons (activated when observing others performing an action) is reactivated during sleep. PMID:21704532

  9. Beam walking can detect differences in walking balance proficiency across a range of sensorimotor abilities.

    PubMed

    Sawers, Andrew; Ting, Lena H

    2015-02-01

    The ability to quantify differences in walking balance proficiency is critical to curbing the rising health and financial costs of falls. Current laboratory-based approaches typically focus on successful recovery of balance while clinical instruments often pose little difficulty for all but the most impaired patients. Rarely do they test motor behaviors of sufficient difficulty to evoke failures in balance control limiting their ability to quantify balance proficiency. Our objective was to test whether a simple beam-walking task could quantify differences in walking balance proficiency across a range of sensorimotor abilities. Ten experts, ten novices, and five individuals with transtibial limb loss performed six walking trials across three different width beams. Walking balance proficiency was quantified as the ratio of distance walked to total possible distance. Balance proficiency was not significantly different between cohorts on the wide-beam, but clear differences between cohorts on the mid and narrow-beams were identified. Experts walked a greater distance than novices on the mid-beam (average of 3.630.04m verus 2.700.21m out of 3.66m; p=0.009), and novices walked further than amputees (1.520.20m; p=0.03). Amputees were unable to walk on the narrow-beam, while experts walked further (3.070.14m) than novices (1.550.26m; p=0.0005). A simple beam-walking task and an easily collected measure of distance traveled detected differences in walking balance proficiency across sensorimotor abilities. This approach provides a means to safely study and evaluate successes and failures in walking balance in the clinic or lab. It may prove useful in identifying mechanisms underlying falls versus fall recoveries. PMID:25648493

  10. Quantum walk public-key cryptographic system

    NASA Astrophysics Data System (ADS)

    Vlachou, C.; Rodrigues, J.; Mateus, P.; Paunković, N.; Souto, A.

    2015-12-01

    Quantum Cryptography is a rapidly developing field of research that benefits from the properties of Quantum Mechanics in performing cryptographic tasks. Quantum walks are a powerful model for quantum computation and very promising for quantum information processing. In this paper, we present a quantum public-key cryptographic system based on quantum walks. In particular, in the proposed protocol the public-key is given by a quantum state generated by performing a quantum walk. We show that the protocol is secure and analyze the complexity of public key generation and encryption/decryption procedures.

  11. Localized quantum walks as secured quantum memory

    NASA Astrophysics Data System (ADS)

    Chandrashekar, C. M.; Busch, Th.

    2015-04-01

    We show that a quantum walk process can be used to construct and secure quantum memory. More precisely, we show that a localized quantum walk with temporal disorder can be engineered to store the information of a single, unknown qubit on a compact position space and faithfully recover it on demand. Since the localization occurs with a finite spread in position space, the stored information of the qubit will be naturally secured from the simple eavesdropper. Our protocol can be adopted to any quantum system for which experimental control over quantum walk dynamics can be achieved.

  12. An experimental analysis of human straight walking

    NASA Astrophysics Data System (ADS)

    Li, Tao; Ceccarelli, Marco

    2013-03-01

    In this paper, an experimental analysis of human straight walking has been presented. Experiments on human walking were carried out by using Cassino tracking system which is a passive cable-based measuring system. This system is adopted because it is capable of both pose and wrench measurements with fairly simple monitoring of operation. By using experimental results, trajectories of a human limb extremity and its posture have been analyzed; forces that are exerted against cables by the limb of a person under test have been measured by force sensors as well. Furthermore, by using experimental tests, modeling and characterization of the human straight walking gait have been proposed.

  13. Does getting a dog increase recreational walking?

    PubMed Central

    Cutt, Hayley E; Knuiman, Matthew W; Giles-Corti, Billie

    2008-01-01

    Background This study examines changes in socio-demographic, environmental and intrapersonal factors associated with dog acquisition in non-dog owners at baseline to 12-months follow-up and the effect of dog acquisition on minutes per week of recreational walking. Methods RESIDE study participants completed self-administered questionnaires (baseline and 12-months follow-up) measuring physical activity, dog ownership, dog walking behavior as well as environmental, intrapersonal and socio-demographic factors. Analysis was restricted to 'Continuing non-owners' (i.e., non-owners at both baseline and follow-up; n = 681) and 'New dog owners' (i.e., non-owners who acquired a dog by follow-up; n = 92). Results Overall, 12% of baseline non-owners had acquired a dog at follow-up. Dog acquisition was associated with working and having children at home. Those who changed from single to couple marital status were also more likely to acquire a dog. The increase in minutes of walking for recreation within the neighborhood from baseline to follow-up was 48 minutes/week for new dog owners compared with 12 minutes/week for continuing non-owners (p < 0.05). After adjusting for baseline variables the effect of dog acquisition on the increase in minutes of recreational walking within the neighborhood was 31 minutes (95% CI: 7.39, 54.22; p < 0.01). However, this reduced to 22 minutes (95% CI: -1.53, 45.42; p > 0.05) after further adjustment for change in baseline to follow-up variables. Increase in intention to walk was the main factor contributing to attenuation of the effect of dog acquisition on recreational walking. Conclusion This study used a large representative sample of non-owners to examine the relationship between dog acquisition and recreational walking and provides evidence to suggest that dog acquisition leads to an increase in walking. The most likely mechanism through which dog acquisition facilitates increased physical activity is through behavioral intention via the dog's positive effect on owner's cognitive beliefs about walking, and through the provision of motivation and social support for walking. The results suggest that behavioral intention mediates the relationship between dog acquisition and walking and that dogs may have a significant role in the maintenance of owner walking behavior. PMID:18366804

  14. Quantum Walk Schemes for Universal Quantum Computation

    NASA Astrophysics Data System (ADS)

    Underwood, Michael S.

    Random walks are a powerful tool for the efficient implementation of algorithms in classical computation. Their quantum-mechanical analogues, called quantum walks, hold similar promise. Quantum walks provide a model of quantum computation that has recently been shown to be equivalent in power to the standard circuit model. As in the classical case, quantum walks take place on graphs and can undergo discrete or continuous evolution, though quantum evolution is unitary and therefore deterministic until a measurement is made. This thesis considers the usefulness of continuous-time quantum walks to quantum computation from the perspectives of both their fundamental power under various formulations, and their applicability in practical experiments. In one extant scheme, logical gates are effected by scattering processes. The results of an exhaustive search for single-qubit operations in this model are presented. It is shown that the number of distinct operations increases exponentially with the number of vertices in the scattering graph. A catalogue of all graphs on up to nine vertices that implement single-qubit unitaries at a specific set of momenta is included in an appendix. I develop a novel scheme for universal quantum computation called the discontinuous quantum walk, in which a continuous-time quantum walker takes discrete steps of evolution via perfect quantum state transfer through small 'widget' graphs. The discontinuous quantum-walk scheme requires an exponentially sized graph, as do prior discrete and continuous schemes. To eliminate the inefficient vertex resource requirement, a computation scheme based on multiple discontinuous walkers is presented. In this model, n interacting walkers inhabiting a graph with 2n vertices can implement an arbitrary quantum computation on an input of length n, an exponential savings over previous universal quantum walk schemes. This is the first quantum walk scheme that allows for the application of quantum error correction. The many-particle quantum walk can be viewed as a single quantum walk undergoing perfect state transfer on a larger weighted graph, obtained via equitable partitioning. I extend this formalism to non-simple graphs. Examples of the application of equitable partitioning to the analysis of quantum walks and many-particle quantum systems are discussed.

  15. Nordic Walking Practice Might Improve Plantar Pressure Distribution

    ERIC Educational Resources Information Center

    Perez-Soriano, Pedro; Llana-Belloch, Salvador; Martinez-Nova, Alfonso; Morey-Klapsing, G.; Encarnacion-Martinez, Alberto

    2011-01-01

    Nordic walking (NW), characterized by the use of two walking poles, is becoming increasingly popular (Morgulec-Adamowicz, Marszalek, & Jagustyn, 2011). We studied walking pressure patterns of 20 experienced and 30 beginner Nordic walkers. Plantar pressures from nine foot zones were measured during trials performed at two walking speeds (preferred

  16. Walking and Eating Behavior of Toddlers at 12 Months Old

    ERIC Educational Resources Information Center

    Koda, Naoko; Akimoto, Yuko; Hirose, Toshiya; Hinobayashi, Toshihiko; Minami, Tetsuhiro

    2004-01-01

    Locomotive and eating behavior of 52 toddlers was observed at 12 months old in a nursery school and investigated in relation to the acquisition of independent walking. The toddlers who acquired walking ate more by themselves using the hands than the toddlers who did not start walking. This suggested that acquisition of walking was associated with…

  17. Walking and Eating Behavior of Toddlers at 12 Months Old

    ERIC Educational Resources Information Center

    Koda, Naoko; Akimoto, Yuko; Hirose, Toshiya; Hinobayashi, Toshihiko; Minami, Tetsuhiro

    2004-01-01

    Locomotive and eating behavior of 52 toddlers was observed at 12 months old in a nursery school and investigated in relation to the acquisition of independent walking. The toddlers who acquired walking ate more by themselves using the hands than the toddlers who did not start walking. This suggested that acquisition of walking was associated with

  18. Nordic Walking Practice Might Improve Plantar Pressure Distribution

    ERIC Educational Resources Information Center

    Perez-Soriano, Pedro; Llana-Belloch, Salvador; Martinez-Nova, Alfonso; Morey-Klapsing, G.; Encarnacion-Martinez, Alberto

    2011-01-01

    Nordic walking (NW), characterized by the use of two walking poles, is becoming increasingly popular (Morgulec-Adamowicz, Marszalek, & Jagustyn, 2011). We studied walking pressure patterns of 20 experienced and 30 beginner Nordic walkers. Plantar pressures from nine foot zones were measured during trials performed at two walking speeds (preferred…

  19. Walking with coffee: Why does it spill?

    NASA Astrophysics Data System (ADS)

    Mayer, H. C.; Krechetnikov, R.

    2012-04-01

    In our busy lives, almost all of us have to walk with a cup of coffee. While often we spill the drink, this familiar phenomenon has never been explored systematically. Here we report on the results of an experimental study of the conditions under which coffee spills for various walking speeds and initial liquid levels in the cup. These observations are analyzed from the dynamical systems and fluid mechanics viewpoints as well as with the help of a model developed here. Particularities of the common cup sizes, the coffee properties, and the biomechanics of walking proved to be responsible for the spilling phenomenon. The studied problem represents an example of the interplay between the complex motion of a cup, due to the biomechanics of a walking individual, and the low-viscosity-liquid dynamics in it.

  20. Community Walking in People with Parkinson's Disease

    PubMed Central

    Lamont, Robyn M.; Morris, Meg E.; Woollacott, Marjorie H.; Brauer, Sandra G.

    2012-01-01

    People with Parkinson's disease often have walking difficulty, and this is likely to be exacerbated while walking in places in the community, where people are likely to face greater and more varied challenges. This study aims to understand the facilitators and the barriers to walking in the community perceived by people with Parkinson's disease. This qualitative study involved 5 focus groups (n = 34) of people with Parkinson's disease and their partners residing in metropolitan and rural regions in Queensland, Australia. Results found that people with PD reported to use internal personal strategies as facilitators to community walking, but identified primarily external factors, particularly the environmental factors as barriers. The adoption of strategies or the use of facilitators allows people with Parkinson's disease to cope so that participants often did not report disability. PMID:22191078

  1. Epidemic spreading driven by biased random walks

    NASA Astrophysics Data System (ADS)

    Pu, Cunlai; Li, Siyuan; Yang, Jian

    2015-08-01

    Random walk is one of the basic mechanisms of many network-related applications. In this paper, we study the dynamics of epidemic spreading driven by biased random walks in complex networks. In our epidemic model, infected nodes send out infection packets by biased random walks to their neighbor nodes, and this causes the infection of susceptible nodes that receive the packets. Infected nodes recover from the infection at a constant rate ?, and will not be infected again after recovery. We obtain the largest instantaneous number of infected nodes and the largest number of ever-infected nodes respectively, by tuning the parameter ? of the biased random walks. Simulation results on model and real-world networks show that spread of the epidemic becomes intense and widespread with increase of either delivery capacity of infected nodes, average node degree, or homogeneity of node degree distribution.

  2. Quantum random walks with decoherent coins

    SciTech Connect

    Brun, Todd A.; Ambainis, Andris; Carteret, H.A.

    2003-03-01

    The quantum random walk has been much studied recently, largely due to its highly nonclassical behavior. In this paper, we study one possible route to classical behavior for the discrete quantum walk on the line: the presence of decoherence in the quantum ''coin'' which drives the walk. We find exact analytical expressions for the time dependence of the first two moments of position, and show that in the long-time limit the variance grows linearly with time, unlike the unitary walk. We compare this to the results of direct numerical simulation, and see how the form of the position distribution changes from the unitary to the usual classical result as we increase the strength of the decoherence.

  3. Walking with coffee: why does it spill?

    PubMed

    Mayer, H C; Krechetnikov, R

    2012-04-01

    In our busy lives, almost all of us have to walk with a cup of coffee. While often we spill the drink, this familiar phenomenon has never been explored systematically. Here we report on the results of an experimental study of the conditions under which coffee spills for various walking speeds and initial liquid levels in the cup. These observations are analyzed from the dynamical systems and fluid mechanics viewpoints as well as with the help of a model developed here. Particularities of the common cup sizes, the coffee properties, and the biomechanics of walking proved to be responsible for the spilling phenomenon. The studied problem represents an example of the interplay between the complex motion of a cup, due to the biomechanics of a walking individual, and the low-viscosity-liquid dynamics in it. PMID:22680548

  4. Measuring Oscillating Walking Paths with a LIDAR

    PubMed Central

    Teixid, Merc; Pallej, Toms; Tresanchez, Marcel; Nogus, Miquel; Palacn, Jordi

    2011-01-01

    This work describes the analysis of different walking paths registered using a Light Detection And Ranging (LIDAR) laser range sensor in order to measure oscillating trajectories during unsupervised walking. The estimate of the gait and trajectory parameters were obtained with a terrestrial LIDAR placed 100 mm above the ground with the scanning plane parallel to the floor to measure the trajectory of the legs without attaching any markers or modifying the floor. Three different large walking experiments were performed to test the proposed measurement system with straight and oscillating trajectories. The main advantages of the proposed system are the possibility to measure several steps and obtain average gait parameters and the minimum infrastructure required. This measurement system enables the development of new ambulatory applications based on the analysis of the gait and the trajectory during a walk. PMID:22163891

  5. Steering random walks with kicked ultracold atoms

    NASA Astrophysics Data System (ADS)

    Wei, Marcel; Groiseau, Caspar; Lam, W. K.; Burioni, Raffaella; Vezzani, Alessandro; Summy, Gil S.; Wimberger, Sandro

    2015-09-01

    The kicking sequence of the atom-optics kicked rotor at quantum resonance can be interpreted as a quantum random walk in momentum space. We show how such a walk can become the basis for nontrivial classical walks by applying a random sequence of intensities and phases of the kicking lattice chosen according to a probability distribution. This distribution converts on average into the final momentum distribution of the kicked atoms. In particular, it is shown that a power-law distribution for the kicking strengths results in a Lvy walk in momentum space and in a power law with the same exponent in the averaged momentum distribution. Furthermore, we investigate the stability of our predictions in the context of a realistic experiment with Bose-Einstein condensates.

  6. Walking (Gait), Balance, and Coordination Problems

    MedlinePLUS

    ... tizanidine are generally effective in treating this symptom. Balance : Balance problems typically result in a swaying and “drunken” ... factors for falls are complex and include: poor balance and slowed walking reduced proprioception (the sensation of ...

  7. Power Demand in Walking and Pace Optimization.

    ERIC Educational Resources Information Center

    Bellemans, A.

    1981-01-01

    Presents an elementary formulation of the work expenditure corresponding to walking, the most common physical exercise. The model described is included in a physics course for freshmen in physical education and physical therapy. (Author/JN)

  8. Care and Operation of Walk-Ins.

    ERIC Educational Resources Information Center

    Bauer, James M.

    1979-01-01

    Problems of owners who use their walk-in coolers and freezers only part of the year demand special consideration. Proper techniques for startup, operation, and shutdown must be used to guarantee efficient, inexpensive operation. (Author)

  9. Real time visualization of quantum walk

    SciTech Connect

    Miyazaki, Akihide; Hamada, Shinji; Sekino, Hideo

    2014-02-20

    Time evolution of quantum particles like electrons is described by time-dependent Schrödinger equation (TDSE). The TDSE is regarded as the diffusion equation of electrons with imaginary diffusion coefficients. And the TDSE is solved by quantum walk (QW) which is regarded as a quantum version of a classical random walk. The diffusion equation is solved in discretized space/time as in the case of classical random walk with additional unitary transformation of internal degree of freedom typical for quantum particles. We call the QW for solution of the TDSE a Schrödinger walk (SW). For observation of one quantum particle evolution under a given potential in atto-second scale, we attempt a successive computation and visualization of the SW. Using Pure Data programming, we observe the correct behavior of a probability distribution under the given potential in real time for observers of atto-second scale.

  10. Adaptive Walking in Alzheimer's Disease

    PubMed Central

    Orcioli-Silva, Diego; Simieli, Lucas; Barbieri, Fabio Augusto; Stella, Florindo; Gobbi, Lilian Teresa Bucken

    2012-01-01

    The aim of this study is to analyze dual-task effects on free and adaptive gait in Alzheimer's disease (AD) patients. Nineteen elders with AD participated in the study. A veteran neuropsychiatrist established the degree of AD in the sample. To determine dual-task effects on free and adaptive gait, patients performed five trials for each experimental condition: free and adaptive gait with and without a dual-task (regressive countdown). Spatial and temporal parameters were collected through an optoelectronic tridimensional system. The central stride was analyzed in free gait, and the steps immediately before (approaching phase) and during the obstacle crossing were analyzed in adaptive gait. Results indicated that AD patients walked more slowly during adaptive gait and free gait, using conservative strategies when confronted either with an obstacle or a secondary task. Furthermore, patients sought for stability to perform the tasks, particularly for adaptive gait with dual task, who used anticipatory and online adjustments to perform the task. Therefore, the increase of task complexity enhances cognitive load and risk of falls for AD patients. PMID:22991684

  11. Design of a walking robot

    NASA Technical Reports Server (NTRS)

    Whittaker, William; Dowling, Kevin

    1994-01-01

    Carnegie Mellon University's Autonomous Planetary Exploration Program (APEX) is currently building the Daedalus robot; a system capable of performing extended autonomous planetary exploration missions. Extended autonomy is an important capability because the continued exploration of the Moon, Mars and other solid bodies within the solar system will probably be carried out by autonomous robotic systems. There are a number of reasons for this - the most important of which are the high cost of placing a man in space, the high risk associated with human exploration and communication delays that make teleoperation infeasible. The Daedalus robot represents an evolutionary approach to robot mechanism design and software system architecture. Daedalus incorporates key features from a number of predecessor systems. Using previously proven technologies, the Apex project endeavors to encompass all of the capabilities necessary for robust planetary exploration. The Ambler, a six-legged walking machine was developed by CMU for demonstration of technologies required for planetary exploration. In its five years of life, the Ambler project brought major breakthroughs in various areas of robotic technology. Significant progress was made in: mechanism and control, by introducing a novel gait pattern (circulating gait) and use of orthogonal legs; perception, by developing sophisticated algorithms for map building; and planning, by developing and implementing the Task Control Architecture to coordinate tasks and control complex system functions. The APEX project is the successor of the Ambler project.

  12. Design of a walking robot

    NASA Astrophysics Data System (ADS)

    Whittaker, William; Dowling, Kevin

    1994-03-01

    Carnegie Mellon University's Autonomous Planetary Exploration Program (APEX) is currently building the Daedalus robot; a system capable of performing extended autonomous planetary exploration missions. Extended autonomy is an important capability because the continued exploration of the Moon, Mars and other solid bodies within the solar system will probably be carried out by autonomous robotic systems. There are a number of reasons for this - the most important of which are the high cost of placing a man in space, the high risk associated with human exploration and communication delays that make teleoperation infeasible. The Daedalus robot represents an evolutionary approach to robot mechanism design and software system architecture. Daedalus incorporates key features from a number of predecessor systems. Using previously proven technologies, the Apex project endeavors to encompass all of the capabilities necessary for robust planetary exploration. The Ambler, a six-legged walking machine was developed by CMU for demonstration of technologies required for planetary exploration. In its five years of life, the Ambler project brought major breakthroughs in various areas of robotic technology. Significant progress was made in: mechanism and control, by introducing a novel gait pattern (circulating gait) and use of orthogonal legs; perception, by developing sophisticated algorithms for map building; and planning, by developing and implementing the Task Control Architecture to coordinate tasks and control complex system functions. The APEX project is the successor of the Ambler project.

  13. Calcaneal loading during walking and running

    NASA Technical Reports Server (NTRS)

    Giddings, V. L.; Beaupre, G. S.; Whalen, R. T.; Carter, D. R.

    2000-01-01

    PURPOSE: This study of the foot uses experimentally measured kinematic and kinetic data with a numerical model to evaluate in vivo calcaneal stresses during walking and running. METHODS: External ground reaction forces (GRF) and kinematic data were measured during walking and running using cineradiography and force plate measurements. A contact-coupled finite element model of the foot was developed to assess the forces acting on the calcaneus during gait. RESULTS: We found that the calculated force-time profiles of the joint contact, ligament, and Achilles tendon forces varied with the time-history curve of the moment about the ankle joint. The model predicted peak talocalcaneal and calcaneocuboid joint loads of 5.4 and 4.2 body weights (BW) during walking and 11.1 and 7.9 BW during running. The maximum predicted Achilles tendon forces were 3.9 and 7.7 BW for walking and running. CONCLUSIONS: Large magnitude forces and calcaneal stresses are generated late in the stance phase, with maximum loads occurring at approximately 70% of the stance phase during walking and at approximately 60% of the stance phase during running, for the gait velocities analyzed. The trajectories of the principal stresses, during both walking and running, corresponded to each other and qualitatively to the calcaneal trabecular architecture.

  14. Convergence of quantum random walks with decoherence

    SciTech Connect

    Fan Shimao; Feng Zhiyong; Yang, Wei-Shih; Xiong Sheng

    2011-10-15

    In this paper, we study the discrete-time quantum random walks on a line subject to decoherence. The convergence of the rescaled position probability distribution p(x,t) depends mainly on the spectrum of the superoperator L{sub kk}. We show that if 1 is an eigenvalue of the superoperator with multiplicity one and there is no other eigenvalue whose modulus equals 1, then P(({nu}/{radical}(t)),t) converges to a convex combination of normal distributions. In terms of position space, the rescaled probability mass function p{sub t}(x,t){identical_to}p({radical}(t)x,t), x is an element of Z/{radical}(t), converges in distribution to a continuous convex combination of normal distributions. We give a necessary and sufficient condition for a U(2) decoherent quantum walk that satisfies the eigenvalue conditions. We also give a complete description of the behavior of quantum walks whose eigenvalues do not satisfy these assumptions. Specific examples such as the Hadamard walk and walks under real and complex rotations are illustrated. For the O(2) quantum random walks, an explicit formula is provided for the scaling limit of p(x,t) and their moments. We also obtain exact critical exponents for their moments at the critical point and show universality classes with respect to these critical exponents.

  15. Uphill and Downhill Walking in Multiple Sclerosis

    PubMed Central

    Samaei, Afshin; Hajihasani, Abdolhamid; Fatemi, Elham; Motaharinezhad, Fatemeh

    2016-01-01

    Background: Various exercise protocols have been recommended for patients with multiple sclerosis (MS). We investigated the effects of uphill and downhill walking exercise on mobility, functional activities, and muscle strength in MS patients. Methods: Thirty-four MS patients were randomly allocated to either the downhill or uphill treadmill walking group for 12 sessions (3 times/wk) of 30 minutes' walking on a 10% negative slope (n = 17) or a 10% positive slope (n = 17), respectively. Measurements were taken before and after the intervention and after 4-week follow-up and included fatigue by Modified Fatigue Impact Scale; mobility by Modified Rivermead Mobility Index; disability by Guy's Neurological Disability Scale; functional activities by 2-Minute Walk Test, Timed 25-Foot Walk test, and Timed Up and Go test; balance indices by Biodex Balance System; and quadriceps and hamstring isometric muscles by torque of left and right knee joints. Analysis of variance with repeated measures was used to investigate the intervention effects on the measurements. Results: After the intervention, significant improvement was found in the downhill group versus the uphill group in terms of fatigue, mobility, and disability indices; functional activities; balance indices; and quadriceps isometric torque (P < .05). The results were stable at 4-week follow-up. Conclusions: Downhill walking on a treadmill may improve muscle performance, functional activity, and balance control in MS patients. These findings support the idea of using eccentric exercise training in MS rehabilitation protocols. PMID:26917996

  16. Developmental Continuity? Crawling, Cruising, and Walking

    PubMed Central

    Adolph, Karen E.; Berger, Sarah E.; Leo, Andrew J.

    2010-01-01

    This research examined developmental continuity between cruising (moving sideways holding onto furniture for support) and walking. Because cruising and walking involve locomotion in an upright posture, researchers have assumed that cruising is functionally related to walking. Study 1 showed that most infants crawl and cruise concurrently prior to walking, amassing several weeks of experience with both skills. Study 2 showed that cruising infants perceive affordances for locomotion over an adjustable gap in a handrail used for manual support, but despite weeks of cruising experience, cruisers are largely oblivious to the dangers of gaps in the floor beneath their feet. Study 3 replicated the floor-gap findings for infants taking their first independent walking steps, and showed that new walkers also misperceive affordances for locomoting between gaps in a handrail. The findings suggest that weeks of cruising do not teach infants a basic fact about walking: the necessity of a floor to support their body. Moreover, this research demonstrated that developmental milestones that are temporally contiguous and structurally similar might have important functional discontinuities. PMID:21399716

  17. Exploring temporal networks with greedy walks

    NASA Astrophysics Data System (ADS)

    Saramki, Jari; Holme, Petter

    2015-12-01

    Temporal networks come with a wide variety of heterogeneities, from burstiness of event sequences to correlations between timings of node and link activations. In this paper, we set to explore the latter by using temporal greedy walks as probes of temporal network structure. Given a temporal network (a sequence of contacts), temporal greedy walks proceed from node to node by always following the first available contact. Because of this, their structure is particularly sensitive to temporal-topological patterns involving repeated contacts between sets of nodes. This becomes evident in their small coverage per step taken as compared to a temporal reference model - in empirical temporal networks, greedy walks often get stuck within small sets of nodes because of correlated contact patterns. While this may also happen in static networks that have pronounced community structure, the use of the temporal reference model takes the underlying static network structure out of the equation and indicates that there is a purely temporal reason for the observations. Further analysis of the structure of greedy walks indicates that burst trains, sequences of repeated contacts between node pairs, are the dominant factor. However, there are larger patterns too, as shown with non-backtracking greedy walks. We proceed further to study the entropy rates of greedy walks, and show that the sequences of visited nodes are more structured and predictable in original data as compared to temporally uncorrelated references. Taken together, these results indicate a richness of correlated temporal-topological patterns in temporal networks.

  18. Does botulinum toxin A improve the walking pattern in children with idiopathic toe-walking?

    PubMed Central

    Gutierrez-Farewik, Elena M.; Bartonek, sa; Tedroff, Kristina; Orefelt, Christina; Haglund-kerlind, Yvonne

    2010-01-01

    Background Numerous recommendations have been made for treating idiopathic toe-walking (ITW), but the treatment results have been questioned. The purpose of this study was to investigate whether botulinum toxin A (BTX) improves the walking pattern in ITW as examined with 3-D gait analysis. Participants and methods A consecutive series of 15 children (aged 513 years) were enrolled in the study. The children underwent a 3-D gait analysis prior to treatment with a total of 6 units/kg bodyweight Botox in the calf muscles and an exercise program. The gait analysis was repeated 3 weeks and 3, 6, and 12 months after treatment. A classification of toe-walking severity was made before treatment and after 12 months. The parents rated the perceived amount of toe-walking prior to treatment and 6 and 12 months after treatment. Results Eleven children completed the 12-month follow-up. The gait analysis results displayed a significant improvement, indicating decreased plantarflexion angle at initial contact and during swing phase and increased dorsiflexion angle during midstance at all post-treatment testing instances. According to the parents perception of toe-walking, 3/11 children followed for 12 months had ceased toe-walking completely, 4/11 decreased toe-walking, and 4/11 continued toe-walking. After 612 months, the toe-walking severity classification improved in 9 of the 14 children for whom data could be assessed. Conclusions A single injection of BTX in combination with an exercise program can improve the walking pattern in children with ITW seen at gait analysis, but the obvious goal of ceasing toe-walking is only occasionally reached. PMID:21804891

  19. Exercise intensity of robot-assisted walking versus overground walking in nonambulatory stroke patients.

    PubMed

    van Nunen, Michiel P M; Gerrits, Karin H L; de Haan, Arnold; Janssen, Thomas W J

    2012-01-01

    It has been suggested that aerobic training should be considered in stroke rehabilitation programs to counteract detrimental health effects and decrease cardiovascular risk caused by inactivity. Robot-assisted treadmill exercise (using a Lokomat device) has the potential to increase the duration of walking therapy relative to conventional overground therapy. We investigated whether exercise intensity during Lokomat therapy is adequate to elicit a training effect and how assistance during walking in the Lokomat affects this exercise intensity. Ten patients with stroke (age 54 +/- 9 yr) walked in both the Lokomat and in a hallway. Furthermore, 10 nondisabled subjects (age 43 +/- 14 yr) walked in the Lokomat at various settings and on a treadmill at various speeds. During walking, oxygen consumption and heart rate were monitored. Results showed that for patients with stroke, exercise intensity did not reach recommended levels (30% heart rate reserve) for aerobic training during Lokomat walking. Furthermore, exercise intensity during walking in the Lokomat (9.3 +/- 1.6 mL/min/kg) was lower than during overground walking (10.4 +/- 1.3 mL/min/kg). Also, different settings of the Lokomat only had small effects on exercise intensity in nondisabled subjects. PMID:23516057

  20. Framework for discrete-time quantum walks and a symmetric walk on a binary tree

    SciTech Connect

    Dimcovic, Zlatko; Rockwell, Daniel; Milligan, Ian; Burton, Robert M.; Kovchegov, Yevgeniy; Nguyen, Thinh

    2011-09-15

    We formulate a framework for discrete-time quantum walks, motivated by classical random walks with memory. We present a specific representation of the classical walk with memory 2, on which this is based. The framework has no need for coin spaces, it imposes no constraints on the evolution operator other than unitarity, and is unifying of other approaches. As an example we construct a symmetric discrete-time quantum walk on the semi-infinite binary tree. The generating function of the amplitude at the root is computed in closed form, as a function of time and the initial level n in the tree, and we find the asymptotic and a full numerical solution for the amplitude. It exhibits a sharp interference peak and a power-law tail, as opposed to the exponentially decaying tail of a broadly peaked distribution of the classical symmetric random walk on a binary tree. The probability peak is orders of magnitude larger than it is for the classical walk (already at small n). The quantum walk shows a polynomial algorithmic speedup in n over the classical walk, which we conjecture to be of the order 2/3, based on strong trends in data.

  1. The effects of neighborhood density and street connectivity on walking behavior: the Twin Cities walking study

    PubMed Central

    Oakes, J Michael; Forsyth, Ann; Schmitz, Kathryn H

    2007-01-01

    A growing body of health and policy research suggests residential neighborhood density and street connectivity affect walking and total physical activity, both of which are important risk factors for obesity and related chronic diseases. The authors report results from their methodologically novel Twin Cities Walking Study; a multilevel study which examined the relationship between built environments, walking behavior and total physical activity. In order to maximize neighborhood-level variation while maintaining the exchangeability of resident-subjects, investigators sampled 716 adult persons nested in 36 randomly selected neighborhoods across four strata defined on density and street-connectivity – a matched sampling design. Outcome measures include two types of self-reported walking (from surveys and diaries) and so-called objective 7-day accelerometry measures. While crude differences are evident across all outcomes, adjusted effects show increased odds of travel walking in higher-density areas and increased odds of leisure walking in low-connectivity areas, but neither density nor street connectivity are meaningfully related to overall mean miles walked per day or increased total physical activity. Contrary to prior research, the authors conclude that the effects of density and block size on total walking and physical activity are modest to non-existent, if not contrapositive to hypotheses. Divergent findings are attributed to this study's sampling design, which tends to mitigate residual confounding by socioeconomic status. PMID:18078510

  2. 10 CFR 429.53 - Walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CONSUMER PRODUCTS AND COMMERCIAL AND INDUSTRIAL EQUIPMENT Certification § 429.53 Walk-in coolers and walk... declaration that the manufacturer has incorporated the applicable design requirements. In addition, for those... that the manufacturer has incorporated the applicable design requirements....

  3. 10 CFR 429.53 - Walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... CONSUMER PRODUCTS AND COMMERCIAL AND INDUSTRIAL EQUIPMENT Certification § 429.53 Walk-in coolers and walk... declaration that the manufacturer has incorporated the applicable design requirements. In addition, for those... that the manufacturer has incorporated the applicable design requirements....

  4. 10 CFR 429.53 - Walk-in coolers and walk-in freezers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... CONSUMER PRODUCTS AND COMMERCIAL AND INDUSTRIAL EQUIPMENT Certification § 429.53 Walk-in coolers and walk... declaration that the manufacturer has incorporated the applicable design requirements. In addition, for those... that the manufacturer has incorporated the applicable design requirements....

  5. Kinematic evaluation of virtual walking trajectories.

    PubMed

    Cirio, Gabriel; Olivier, Anne-Hlne; Marchal, Maud; Pettr, Julien

    2013-04-01

    Virtual walking, a fundamental task in Virtual Reality (VR), is greatly influenced by the locomotion interface being used, by the specificities of input and output devices, and by the way the virtual environment is represented. No matter how virtual walking is controlled, the generation of realistic virtual trajectories is absolutely required for some applications, especially those dedicated to the study of walking behaviors in VR, navigation through virtual places for architecture, rehabilitation and training. Previous studies focused on evaluating the realism of locomotion trajectories have mostly considered the result of the locomotion task (efficiency, accuracy) and its subjective perception (presence, cybersickness). Few focused on the locomotion trajectory itself, but in situation of geometrically constrained task. In this paper, we study the realism of unconstrained trajectories produced during virtual walking by addressing the following question: did the user reach his destination by virtually walking along a trajectory he would have followed in similar real conditions? To this end, we propose a comprehensive evaluation framework consisting on a set of trajectographical criteria and a locomotion model to generate reference trajectories. We consider a simple locomotion task where users walk between two oriented points in space. The travel path is analyzed both geometrically and temporally in comparison to simulated reference trajectories. In addition, we demonstrate the framework over a user study which considered an initial set of common and frequent virtual walking conditions, namely different input devices, output display devices, control laws, and visualization modalities. The study provides insight into the relative contributions of each condition to the overall realism of the resulting virtual trajectories. PMID:23428452

  6. Assessing walking behaviors of selected subpopulations.

    PubMed

    Le Masurier, Guy C; Bauman, Adrian E; Corbin, Charles B; Konopack, James F; Umstattd, Renee M; VAN Emmerik, Richard E A

    2008-07-01

    Recent innovations in physical activity (PA) assessment have made it possible to assess the walking behaviors of a wide variety of populations. Objective measurement methods (e.g., pedometers, accelerometers) have been widely used to assess walking and other prevalent types of PA. Questionnaires suitable for international populations (e.g., the International Physical Activity Questionnaire and the Global Physical Activity Questionnaire) and measurement techniques for the assessment of gait patterns in disabled populations allow for the study of walking and its health benefits among many populations. Results of studies using the aforementioned techniques indicate that children are more active than adolescents and adolescents are more active than adults. Males, particularly young males, are typically more active than females. The benefits associated with regular participation in PA for youth and walking for older adults have been well documented, although improvements in the assessments of physical, cognitive, and psychosocial parameters must be made if we are to fully understand the benefits of walking for people of all ages. Most youth meet appropriate age-related PA activity recommendations, but adults, particularly older adults and adults with disabilities, are less likely to meet PA levels necessary for the accrual of health benefits. International studies indicate variation in walking by culture. It is clear, however, that walking is a prevalent form of PA across countries and a movement form that has great potential in global PA promotion. Continued development of measurement techniques that allow for the study of individualized gait patterns will help us add to the already rich body of knowledge on chronically disabled populations and allow for individual prescriptions for these populations. PMID:18562977

  7. Walk Score and Australian adults' home-based walking for transport.

    PubMed

    Cole, Rachel; Dunn, Peter; Hunter, Ian; Owen, Neville; Sugiyama, Takemi

    2015-09-01

    The relationships of Walk Score, a publicly-accessible walkability assessment tool, with walking for transport to and from home were examined among a large representative sample of Australian adults aged 18-64 years (N=16,944). Residents in highly and somewhat walkable areas were twice and 1.4 times more likely to accumulate 30 min of walking per day compared to those in very car-dependent neighborhoods, respectively. Mean duration of walking was also longer for participants living in highly and somewhat walkable areas compared to those in very car-dependent areas. Walk Score has potential as a widely-applicable tool for identifying the walkability of local neighborhoods. PMID:26209804

  8. Torque-stiffness-controlled dynamic walking with central pattern generators.

    PubMed

    Huang, Yan; Vanderborght, Bram; Van Ham, Ronald; Wang, Qining

    2014-12-01

    Walking behavior is modulated by controlling joint torques in most existing passivity-based bipeds. Controlled Passive Walking with adaptable stiffness exhibits controllable natural motions and energy efficient gaits. In this paper, we propose torque-stiffness-controlled dynamic bipedal walking, which extends the concept of Controlled Passive Walking by introducing structured control parameters and a bio-inspired control method with central pattern generators. The proposed walking paradigm is beneficial in clarifying the respective effects of the external actuation and the internal natural dynamics. We present a seven-link biped model to validate the presented walking. Effects of joint torque and joint stiffness on gait selection, walking performance and walking pattern transitions are studied in simulations. The work in this paper develops a new solution of motion control of bipedal robots with adaptable stiffness and provides insights of efficient and sophisticated walking gaits of humans. PMID:25128320

  9. Tiotropium improves walking endurance in COPD.

    PubMed

    Bdard, M-E; Brouillard, C; Pepin, V; Provencher, S; Milot, J; Lacasse, Y; Leblanc, P; Maltais, F

    2012-02-01

    The primary objective of this study was to evaluate the effects of a 3-week treatment with tiotropium on walking capacity in chronic obstructive pulmonary disease (COPD). After familiarisation with study procedures, 36 patients were randomised to receive tiotropium 18 ?g once daily or a matching placebo in a double-blind, parallel-group study. Pre- (trough) and 2-h post-dose pulmonary function was measured. An endurance shuttle walk was then completed. The same procedures were repeated after 3 weeks of treatment. Ventilatory parameters were monitored during exercise. At 3 weeks, tiotropium significantly improved walking endurance time in comparison with placebo, with a meansd between-group difference of 128141 s (p=0.017). At 3 weeks, trough values for forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC) were significantly improved with tiotropium in comparison with placebo. The post-dose response to tiotropium was statistically superior to placebo after the first dose and after 3 weeks of treatment for FEV(1), FVC and inspiratory capacity. Ventilation and tidal volume at the end of walking were significantly improved with tiotropium. 3 weeks of tiotropium resulted in a greater walking endurance in patients with COPD. Improvements in FEV(1), maximal ventilation and tidal volume may contribute to this enhanced exercise capacity. PMID:21700602

  10. Structural properties of self-attracting walks.

    PubMed

    Ordemann, A; Tomer, E; Berkolaiko, G; Havlin, S; Bunde, A

    2001-10-01

    Self-attracting walks (SATW) with attractive interaction u>0 display a swelling-collapse transition at a critical u(c) for dimensions d>or=2, analogous to the Theta transition of polymers. We are interested in the structure of the clusters generated by SATW below u(c) (swollen walk), above u(c) (collapsed walk), and at u(c), which can be characterized by the fractal dimensions of the clusters d(f) and their interface d(I). Using scaling arguments and Monte Carlo simulations, we find that for uwalks. For u>u(c), the clusters are compact, i.e., d(f)=d and d(I)=d-1. At u(c), the SATW is in a new universality class. The clusters are compact in both d=2 and d=3, but their interface is fractal: d(I)=1.50+/-0.01 and 2.73+/-0.03 in d=2 and d=3, respectively. In d=1, where the walk is collapsed for all u and no swelling-collapse transition exists, we derive analytical expressions for the average number of visited sites and the mean time to visit S sites. PMID:11690100

  11. Nordic walking improves mobility in Parkinson's disease.

    PubMed

    van Eijkeren, Frank J M; Reijmers, Ruud S J; Kleinveld, Mirjam J; Minten, Angret; Bruggen, Jan Pieter Ter; Bloem, Bastiaan R

    2008-11-15

    Nordic walking may improve mobility in Parkinson's disease (PD). Here, we examined whether the beneficial effects persist after the training period. We included 19 PD patients [14 men; mean age 67.0 years (range 58-76); Hoehn and Yahr stage range 1-3] who received a 6-week Nordic walking exercise program. Outcome was assessed prior to training (T1), immediately after the training period (T2) and-in a subgroup of 9 patients--5 months after training (T3). At T2, we observed a significant improvement in timed 10-m walking, the timed get-up-and-go-test (TUG), the 6-min walking test and quality of life (PDQ-39). All treatment effects persisted at T3. Compliance was excellent, and there were no adverse effects. These preliminary findings suggest that Nordic walking could provide a safe, effective, and enjoyable way to reduce physical inactivity in PD and to improve the quality of life. A large randomized clinical trial now appears justified. PMID:18816697

  12. The discrete-time quaternionic quantum walk on a graph

    NASA Astrophysics Data System (ADS)

    Konno, Norio; Mitsuhashi, Hideo; Sato, Iwao

    2016-02-01

    Recently, the quaternionic quantum walk was formulated by the first author as a generalization of discrete-time quantum walks. We deal with the right eigenvalue problem of quaternionic matrices in order to study spectra of the transition matrix of a quaternionic quantum walk. The way to obtain all the right eigenvalues of a quaternionic matrix is given. From the unitary condition on the transition matrix of a quaternionic quantum walk, we deduce some remarkable properties of it. Our main results determine all the right eigenvalues of the quaternionic quantum walk by using those of the corresponding weighted matrix. In addition, we give some examples of quaternionic quantum walks and their right eigenvalues.

  13. Mean first return time for random walks on weighted networks

    NASA Astrophysics Data System (ADS)

    Jing, Xing-Li; Ling, Xiang; Long, Jiancheng; Shi, Qing; Hu, Mao-Bin

    2015-11-01

    Random walks on complex networks are of great importance to understand various types of phenomena in real world. In this paper, two types of biased random walks on nonassortative weighted networks are studied: edge-weight-based random walks and node-strength-based random walks, both of which are extended from the normal random walk model. Exact expressions for stationary distribution and mean first return time (MFRT) are derived and examined by simulation. The results will be helpful for understanding the influences of weights on the behavior of random walks.

  14. Gaussian Networks Generated by Random Walks

    NASA Astrophysics Data System (ADS)

    Javarone, Marco Alberto

    2015-04-01

    We propose a random walks based model to generate complex networks. Many authors studied and developed different methods and tools to analyze complex networks by random walk processes. Just to cite a few, random walks have been adopted to perform community detection, exploration tasks and to study temporal networks. Moreover, they have been used also to generate networks with different topologies (e.g., scale-free). In this work, we define a random walker that plays the role of "edges-generator". In particular, the random walker generates new connections and uses these ones to visit each node of a network. As result, the proposed model allows to achieve networks provided with a Gaussian degree distribution; moreover we found that some properties of achieved Gaussian networks, as the clustering coefficient and the assortativity, show a critical behavior. Finally, we performed numerical simulations to study the behavior and the properties of the cited model.

  15. Random walks of oriented particles on fractals

    NASA Astrophysics Data System (ADS)

    Haber, Ren; Prehl, Janett; Hoffmann, Karl Heinz; Herrmann, Heiko

    2014-04-01

    Random walks of point particles on fractals exhibit subdiffusive behavior, where the anomalous diffusion exponent is smaller than one, and the corresponding random walk dimension is larger than two. This is due to the limited space available in fractal structures. Here, we endow the particles with an orientation and analyze their dynamics on fractal structures. In particular, we focus on the dynamical consequences of the interactions between the local surrounding fractal structure and the particle orientation, which are modeled using an appropriate move class. These interactions can lead to particles becoming temporarily or permanently stuck in parts of the structure. A surprising finding is that the random walk dimension is not affected by the orientation while the diffusion constant shows a variety of interesting and surprising features.

  16. Universal quantum computation by discontinuous quantum walk

    SciTech Connect

    Underwood, Michael S.; Feder, David L.

    2010-10-15

    Quantum walks are the quantum-mechanical analog of random walks, in which a quantum ''walker'' evolves between initial and final states by traversing the edges of a graph, either in discrete steps from node to node or via continuous evolution under the Hamiltonian furnished by the adjacency matrix of the graph. We present a hybrid scheme for universal quantum computation in which a quantum walker takes discrete steps of continuous evolution. This ''discontinuous'' quantum walk employs perfect quantum-state transfer between two nodes of specific subgraphs chosen to implement a universal gate set, thereby ensuring unitary evolution without requiring the introduction of an ancillary coin space. The run time is linear in the number of simulated qubits and gates. The scheme allows multiple runs of the algorithm to be executed almost simultaneously by starting walkers one time step apart.

  17. Mesoscopic description of random walks on combs

    NASA Astrophysics Data System (ADS)

    Méndez, Vicenç; Iomin, Alexander; Campos, Daniel; Horsthemke, Werner

    2015-12-01

    Combs are a simple caricature of various types of natural branched structures, which belong to the category of loopless graphs and consist of a backbone and branches. We study continuous time random walks on combs and present a generic method to obtain their transport properties. The random walk along the branches may be biased, and we account for the effect of the branches by renormalizing the waiting time probability distribution function for the motion along the backbone. We analyze the overall diffusion properties along the backbone and find normal diffusion, anomalous diffusion, and stochastic localization (diffusion failure), respectively, depending on the characteristics of the continuous time random walk along the branches, and compare our analytical results with stochastic simulations.

  18. Quantum random-walk search algorithm

    SciTech Connect

    Shenvi, Neil; Whaley, K. Birgitta; Kempe, Julia

    2003-05-01

    Quantum random walks on graphs have been shown to display many interesting properties, including exponentially fast hitting times when compared with their classical counterparts. However, it is still unclear how to use these novel properties to gain an algorithmic speedup over classical algorithms. In this paper, we present a quantum search algorithm based on the quantum random-walk architecture that provides such a speedup. It will be shown that this algorithm performs an oracle search on a database of N items with O({radical}(N)) calls to the oracle, yielding a speedup similar to other quantum search algorithms. It appears that the quantum random-walk formulation has considerable flexibility, presenting interesting opportunities for development of other, possibly novel quantum algorithms.

  19. Idiopathic Toe Walking: A Gait Laboratory Review.

    PubMed

    O'Sullivan, R; O'Brien, T

    2015-01-01

    Idiopathic toe walking (ITW) is defined as one who is neurologically normal but demonstrates a preference for walking on the toes. It is a diagnosis of exclusion so differential diagnoses such as cerebral palsy, neuropathy or myopathy must be ruled out. A review of 102 patients attending a gait laboratory with a presumptive diagnosis of ITW found that gait analysis data agreed with this diagnosis in 81 (79.4%) of cases while the remaining 21 (20.6%) were not typical of this diagnosis. The features found to be significantly different between the groups were Babinski response, fast stretch of the gastrocnemius, knee flexion at initial contact and asymmetry at the ankles during gait. This study highlights that clinical gait analysis can be a useful, non-invasive means of diagnosing idiopathic toe walking and recommending appropriate intervention based on clinical and dynamic assessment of calf tightness. PMID:26349353

  20. Walking with continuous positive airway pressure.

    PubMed

    Dieperink, W; Goorhuis, J F; de Weerd, W; Hazenberg, A; Zijlstra, J G; Nijsten, M W N

    2006-04-01

    A ventilator-dependent child had been in the paediatric intensive care unit (PICU) ever since birth. As a result, she had fallen behind considerably in her development. After 18 months, continuous positive airway pressure was successfully administered via a tracheostomy tube with a novel lightweight device. This enabled her to walk in the PICU. With this device, the child was discharged home where she could walk with an action range of 10 m. Subsequently, her psychomotor development improved remarkably. To the authors' knowledge, this is the first case report of a patient, adult or paediatric, who could actually walk with a sufficient radius of action while receiving long-term respiratory support. PMID:16585093

  1. Spherically symmetric random walks in noninteger dimension

    SciTech Connect

    Bender, C.M. ); Boettcher, S. ); Moshe, M. )

    1994-09-01

    A previous article proposed a new kind of random walk on a spherically symmetric lattice in arbitrary noninteger dimension [ital D]. Such a lattice avoids the problems associated with a hypercubic lattice in noninteger dimension. This article examines the nature of spherically symmetric random walks in detail. A large-time asymptotic analysis of these random walks is performed and the results are used to determine the Hausdorff dimension of the process. Exact results are obtained in terms of Hurwitz functions (incomplete zeta functions) for the probability of a walker going from one region of the spherical lattice to another. Finally, it is shown that the probability that the paths of [ital K] independent random walkers will intersect vanishes in the continuum limit if [ital D][gt]2[ital K]/([ital K][minus]1).

  2. Swarming bacteria migrate by Lvy Walk

    PubMed Central

    Ariel, Gil; Rabani, Amit; Benisty, Sivan; Partridge, Jonathan D.; Harshey, Rasika M.; Be'er, Avraham

    2015-01-01

    Individual swimming bacteria are known to bias their random trajectories in search of food and to optimize survival. The motion of bacteria within a swarm, wherein they migrate as a collective group over a solid surface, is fundamentally different as typical bacterial swarms show large-scale swirling and streaming motions involving millions to billions of cells. Here by tracking trajectories of fluorescently labelled individuals within such dense swarms, we find that the bacteria are performing super-diffusion, consistent with Lvy walks. Lvy walks are characterized by trajectories that have straight stretches for extended lengths whose variance is infinite. The evidence of super-diffusion consistent with Lvy walks in bacteria suggests that this strategy may have evolved considerably earlier than previously thought. PMID:26403719

  3. Humanoid robot Lola: design and walking control.

    PubMed

    Buschmann, Thomas; Lohmeier, Sebastian; Ulbrich, Heinz

    2009-01-01

    In this paper we present the humanoid robot LOLA, its mechatronic hardware design, simulation and real-time walking control. The goal of the LOLA-project is to build a machine capable of stable, autonomous, fast and human-like walking. LOLA is characterized by a redundant kinematic configuration with 7-DoF legs, an extremely lightweight design, joint actuators with brushless motors and an electronics architecture using decentralized joint control. Special emphasis was put on an improved mass distribution of the legs to achieve good dynamic performance. Trajectory generation and control aim at faster, more flexible and robust walking. Center of mass trajectories are calculated in real-time from footstep locations using quadratic programming and spline collocation methods. Stabilizing control uses hybrid position/force control in task space with an inner joint position control loop. Inertial stabilization is achieved by modifying the contact force trajectories. PMID:19665558

  4. Swarming bacteria migrate by Lvy Walk.

    PubMed

    Ariel, Gil; Rabani, Amit; Benisty, Sivan; Partridge, Jonathan D; Harshey, Rasika M; Be'er, Avraham

    2015-01-01

    Individual swimming bacteria are known to bias their random trajectories in search of food and to optimize survival. The motion of bacteria within a swarm, wherein they migrate as a collective group over a solid surface, is fundamentally different as typical bacterial swarms show large-scale swirling and streaming motions involving millions to billions of cells. Here by tracking trajectories of fluorescently labelled individuals within such dense swarms, we find that the bacteria are performing super-diffusion, consistent with Lvy walks. Lvy walks are characterized by trajectories that have straight stretches for extended lengths whose variance is infinite. The evidence of super-diffusion consistent with Lvy walks in bacteria suggests that this strategy may have evolved considerably earlier than previously thought. PMID:26403719

  5. Interacting growth walk on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Narasimhan, S. L.; Sridhar, V.; Murthy, K. P. N.

    2003-03-01

    The interacting growth walk (IGW) is a kinetic algorithm proposed recently for generating long, lattice polymer configurations. The growth process in IGW is tuned by a parameter called the growth temperature TG=1/( kB?G). In this paper we consider IGW on a honeycomb lattice. We take the non-bonded nearest neighbour contact energy as ?=-1. We show that at ?G=0, IGW algorithm generates a canonical ensemble of interacting self-avoiding walks at ?= ??(? G=0)= ln(2) . However for ?G>0, IGW generates an ensemble of polymer configurations most of which are in equilibrium at ?= ??(? G) . The remaining ones are frozen in non-equilibrium configurations.

  6. Regional plantar pressure during walking, stair ascent and descent.

    PubMed

    Rao, Smita; Carter, Sylvester

    2012-06-01

    Regional plantar pressures during stair walking may be injurious in at risk populations. However, limited data are available examining the reliability of plantar pressure data collected during stair walking. The aims of this study were three fold; to assess the reliability of the plantar pressure data recorded during stair walking, to assess the effects of level ground and stair walking on plantar loading, and to develop regression equations to predict regional plantar pressures in stair walking from those collected on level ground. Fifteen subjects without conditions affecting their ability to walk on level surfaces or stairs were recruited. Each participant performed at least 10 steps in level ground and stair walking while plantar pressure data were recorded in six foot regions. Reliability was assessed using Intraclass Correlation Coefficient. A repeated measures ANOVA was used to assess the effect of activity on plantar pressure, and a linear regression was used to predict forefoot loading during stair walking. A reliability of 0.9 was achieved within 10 steps in all foot regions, with the forefoot requiring fewer steps. Plantar pressures were influenced by both, foot region and activity, with the heel and forefoot regions generally experiencing lower peak pressures and maximal forces during stair walking than level ground walking. The regression equations predicting peak pressure during stair walking accounted for between 37% and 70% of the variance of the stair walking data. These findings establish the reliability of plantar pressure data collected during stair walking. Future studies should investigate these parameters in clinical populations. PMID:22537610

  7. Environmental factors influencing older adults walking for transportation: a study using walk-along interviews

    PubMed Central

    2012-01-01

    Background Current knowledge on the relationship between the physical environment and walking for transportation among older adults (? 65?years) is limited. Qualitative research can provide valuable information and inform further research. However, qualitative studies are scarce and fail to include neighborhood outings necessary to study participants experiences and perceptions while interacting with and interpreting the local social and physical environment. The current study sought to uncover the perceived environmental influences on Flemish older adults walking for transportation. To get detailed and context-sensitive environmental information, it used walk-along interviews. Methods Purposeful convenience sampling was used to recruit 57 older adults residing in urban or semi-urban areas. Walk-along interviews to and from a destination (e.g. a shop) located within a 15 minutes walk from the participants home were conducted. Content analysis was performed using NVivo 9 software (QSR International). An inductive approach was used to derive categories and subcategories from the data. Results Data were categorized in the following categories and subcategories: access to facilities (shops & services, public transit, connectivity), walking facilities (sidewalk quality, crossings, legibility, benches), traffic safety (busy traffic, behavior of other road users), familiarity, safety from crime (physical factors, other persons), social contacts, aesthetics (buildings, natural elements, noise & smell, openness, decay) and weather. Conclusions The findings indicate that to promote walking for transportation a neighborhood should provide good access to shops and services, well-maintained walking facilities, aesthetically appealing places, streets with little traffic and places for social interaction. In addition, the neighborhood environment should evoke feelings of familiarity and safety from crime. Future quantitative studies should investigate if (changes in) these environmental factors relate to (changes in) older adults walking for transportation. PMID:22780948

  8. Intra-limb coordination while walking is affected by cognitive load and walking speed.

    PubMed

    Ghanavati, Tabassom; Salavati, Mahyar; Karimi, Noureddin; Negahban, Hossein; Ebrahimi Takamjani, Ismail; Mehravar, Mohammad; Hessam, Masumeh

    2014-07-18

    Knowledge about intra-limb coordination (ILC) during challenging walking conditions provides insight into the adaptability of central nervous system (CNS) for controlling human gait. We assessed the effects of cognitive load and speed on the pattern and variability of the ILC in young people during walking. Thirty healthy young people (19 female and 11 male) participated in this study. They were asked to perform 9 walking trials on a treadmill, including walking at three paces (preferred, slower and faster) either without a cognitive task (single-task walking) or while subtracting 1?s or 3?s from a random three-digit number (simple and complex dual-task walking, respectively). Deviation phase (DP) and mean absolute relative phase (MARP) values-indicators of variability and phase dynamic of ILC, respectively-were calculated using the data collected by a motion capture system. We used a two-way repeated measure analysis of variance for statistical analysis. The results showed that cognitive load had a significant main effect on DP of right shank-foot and thigh-shank, left shank-foot and pelvis-thigh (p<0.05), and MARP of both thigh-shank segments (p<0.01). In addition, the main effect of walking speed was significant on DP of all segments in each side and MARP of both thigh-shank and pelvis-thigh segments (p<0.001). The interaction of cognitive load and walking speed was only significant for MARP values of left shank-foot and right pelvis-thigh (p<0.05 and p<0.001, respectively). We suggest that cognitive load and speed could significantly affect the ILC and variability and phase dynamic during walking. PMID:24861632

  9. Paralyzed Man Walks Using Technology That Bypasses Spinal Cord

    MedlinePLUS

    ... html Paralyzed Man Walks Using Technology That Bypasses Spinal Cord Brain signals travel through a computer that sends ... system like this might help people with a spinal cord injury regain some ability to walk, the researchers ...

  10. Fifteen-minute consultation: A child with toe walking.

    PubMed

    Sivaramakrishnan, Shobha; Seal, Arnab

    2015-10-01

    Toe walking is a common developmental phenomenon in young children. It is usually benign and self-limiting. Toe walking can be a presenting sign of some serious underlying disorders and idiopathic toe walking is a diagnosis of exclusion. Persistent toe walking can lead to limited ankle dorsiflexion which may cause functional problems. Specific interventions depend on underlying cause and may range from verbal reinforcement to serial casting and surgery. PMID:25855215

  11. Exploring Space and Place with Walking Interviews

    ERIC Educational Resources Information Center

    Jones, Phil; Bunce, Griff; Evans, James; Gibbs, Hannah; Hein, Jane Ricketts

    2008-01-01

    This article explores the use of walking interviews as a research method. In spite of a wave of interest in methods which take interviewing out of the "safe," stationary environment, there has been limited work critically examining the techniques for undertaking such work. Curiously for a method which takes an explicitly spatial approach, few

  12. Two-step Dirichlet random walks

    NASA Astrophysics Data System (ADS)

    Le Caër, Gérard

    2015-07-01

    Random walks of n steps taken into independent uniformly random directions in a d-dimensional Euclidean space (d ⩾ 2) , which are characterized by a sum of step lengths which is fixed and taken to be 1 without loss of generality, are named "Dirichlet" when this constraint is realized via a Dirichlet law of step lengths. The latter continuous multivariate distribution, which depends on n positive parameters, generalizes the beta distribution (n = 2) . It is simply obtained from n independent gamma random variables with identical scale factors. Previous literature studies of these random walks dealt with symmetric Dirichlet distributions whose parameters are all equal to a value q which takes half-integer or integer values. In the present work, the probability density function of the distance from the endpoint to the origin is first made explicit for a symmetric Dirichlet random walk of two steps. It is valid for any positive value of q and for all d ⩾ 2. The latter pdf is used in turn to express the related density of a random walk of two steps whose step length is distributed according to an asymmetric beta distribution which depends on two parameters, namely q and q + s where s is a positive integer.

  13. The Physics of a Walking Robot

    ERIC Educational Resources Information Center

    Guemez, J.; Fiolhais, M.

    2013-01-01

    The physics of walking is explored, using a toy as a concrete example and a "toy model" applied to it. Besides using Newton's second law, the problem is also discussed from the thermodynamical perspective. Once the steady state (constant velocity) is achieved, we show that the internal energy of the toy is dissipated as heat in the

  14. Coyote Walking Through Post-Wildfires

    USGS Multimedia Gallery

    The next photo on the camera at 11:12 p.m. PST on Oct. 23, 2007, shows a coyote walking out of the wash at night, a day and a half after the fire, heading back in the direction from which the coyote was running on the early morning of Oct. 22, 2007. Photo credit: USGS...

  15. Myths about the Country Walk Case

    ERIC Educational Resources Information Center

    Cheit, Ross E.; Mervis, David

    2007-01-01

    The Country Walk case in Dade County, Florida was long considered a model for how to prosecute a multi-victim child sexual abuse case involving young children. In the past 10 years, however, a contrary view has emerged that the case was tainted by improper interviewing and was likely a false conviction. This is the first scholarly effort to assess

  16. Elementary Education: Elementary Students Simulate Moon Walk.

    ERIC Educational Resources Information Center

    Aviation/Space, 1980

    1980-01-01

    Describes the project of a fourth- and fifth-grade class in simulating a moon walk. Teams consisted of the astronauts, the life support team, the flight program team, the communications team, the scientific team, and the construction team. Their visit to the Marshall Space Flight Center is also described. (SA)

  17. Grover search with lackadaisical quantum walks

    NASA Astrophysics Data System (ADS)

    Wong, Thomas G.

    2015-10-01

    The lazy random walk, where the walker has some probability of staying put, is a useful tool in classical algorithms. We propose a quantum analogue, the lackadaisical quantum walk, where each vertex is given l self-loops, and we investigate its effects on Grovers algorithm when formulated as search for a marked vertex on the complete graph of N vertices. For the discrete-time quantum walk using the phase flip coin, adding a self-loop to each vertex boosts the success probability from 1/2 to 1. Additional self-loops, however, decrease the success probability. Using instead the Shenvi, Kempe, and Whaley (2003) coin, adding self-loops simply slows down the search. These coins also differ in that the first is faster than classical when l scales less than N, while the second requires that l scale less than N 2. Finally, continuous-time quantum walks differ from both of these discrete-time examplesthe self-loops make no difference at all. These behaviors generalize to multiple marked vertices.

  18. Moments of coinless quantum walks on lattices

    NASA Astrophysics Data System (ADS)

    Santos, Raqueline Azevedo Medeiros; Portugal, Renato; Boettcher, Stefan

    2015-09-01

    The properties of the coinless quantum-walk model have not been as thoroughly analyzed as those of the coined model. Both evolve in discrete time steps, but the former uses a smaller Hilbert space, which is spanned merely by the site basis. Besides, the evolution operator can be obtained using a process of lattice tessellation, which is very appealing. The moments of the probability distribution play an important role in the context of quantum walks. The ballistic behavior of the mean square displacement indicates that quantum-walk-based algorithms are faster than random-walk-based ones. In this paper, we obtain analytical expressions for the moments of the coinless model on d-dimensional lattices by employing the methods of Fourier transforms and generating functions. The mean square displacement for large times is explicitly calculated for the one- and two-dimensional lattices, and using optimization methods, the parameter values that give the largest spread are calculated and compared with the equivalent ones of the coined model. Although we have employed asymptotic methods, our approximations are accurate even for small numbers of time steps.

  19. Saccadic body turns in walking Drosophila

    PubMed Central

    Geurten, Bart R. H.; Jhde, Philipp; Corthals, Kristina; Gpfert, Martin C.

    2014-01-01

    Drosophila melanogaster structures its optic flow during flight by interspersing translational movements with abrupt body rotations. Whether these body saccades are accompanied by steering movements of the head is a matter of debate. By tracking single flies moving freely in an arena, we now discovered that walking Drosophila also perform saccades. Movement analysis revealed that the flies separate rotational from translational movements by quickly turning their bodies by 15 degrees within a tenth of a second. Although walking flies moved their heads by up to 20 degrees about their bodies, their heads moved with the bodies during saccadic turns. This saccadic strategy contrasts with the head saccades reported for e.g., blowflies and honeybees, presumably reflecting optical constraints: modeling revealed that head saccades as described for these latter insects would hardly affect the retinal input in Drosophila because of the lower acuity of its compound eye. The absence of head saccades in Drosophila was associated with the absence of haltere oscillations, which seem to guide head movements in other flies. In addition to adding new twists to Drosophila walking behavior, our analysis shows that Drosophila does not turn its head relative to its body when turning during walking. PMID:25386124

  20. Walking-Beam Solar-Cell Conveyor

    NASA Technical Reports Server (NTRS)

    Feder, H.; Frasch, W.

    1982-01-01

    Microprocessor-controlled walking-beam conveyor moves cells between work stations in automated assembly line. Conveyor has arm at each work station. In unison arms pick up all solar cells and advance them one station; then beam retracks to be in position for next step. Microprocessor sets beam stroke, speed, and position.

  1. Healthy Living Initiative: Running/Walking Club

    ERIC Educational Resources Information Center

    Stylianou, Michalis; Kulinna, Pamela Hodges; Kloeppel, Tiffany

    2014-01-01

    This study was grounded in the public health literature and the call for schools to serve as physical activity intervention sites. Its purpose was twofold: (a) to examine the daily distance covered by students in a before-school running/walking club throughout 1 school year and (b) to gain insights on the teachers perspectives of the club.

  2. Exploring complex networks through random walks

    NASA Astrophysics Data System (ADS)

    Costa, Luciano Da Fontoura; Travieso, Gonzalo

    2007-01-01

    Most real complex networks—such as protein interactions, social contacts, and the Internet—are only partially known and available to us. While the process of exploring such networks in many cases resembles a random walk, it becomes a key issue to investigate and characterize how effectively the nodes and edges of such networks can be covered by different strategies. At the same time, it is critically important to infer how well can topological measurements such as the average node degree and average clustering coefficient be estimated during such network explorations. The present article addresses these problems by considering random, Barabási-Albert (BA), and geographical network models with varying connectivity explored by three types of random walks: traditional, preferential to untracked edges, and preferential to unvisited nodes. A series of relevant results are obtained, including the fact that networks of the three studied models with the same size and average node degree allow similar node and edge coverage efficiency, the identification of linear scaling with the size of the network of the random walk step at which a given percentage of the nodes/edges is covered, and the critical result that the estimation of the averaged node degree and clustering coefficient by random walks on BA networks often leads to heavily biased results. Many are the theoretical and practical implications of such results.

  3. Assessment of a Solar System Walk

    ERIC Educational Resources Information Center

    LoPresto, Michael C.; Murrell, Steven R.; Kirchner, Brian

    2010-01-01

    The idea of sending students and the general public on a walk through a scale model of the solar system in an attempt to instill an appreciation of the relative scales of the sizes of the objects compared to the immense distances between them is certainly not new. A good number of such models exist, including one on the National Mall in

  4. A three-dimensional human walking model

    NASA Astrophysics Data System (ADS)

    Yang, Q. S.; Qin, J. W.; Law, S. S.

    2015-11-01

    A three-dimensional human bipedal walking model with compliant legs is presented in this paper. The legs are modeled with time-variant dampers, and the model is able to characterize the gait pattern of an individual using a minimal set of parameters. Feedback control, for both the forward and lateral movements, is implemented to regulate the walking performance of the pedestrian. The model provides an improvement over classic invert pendulum models. Numerical studies were undertaken to investigate the effects of leg stiffness and attack angle. Simulation results show that when walking at a given speed, increasing the leg stiffness with a constant attack angle results in a longer step length, a higher step frequency, a faster walking speed and an increase in both the peak vertical and lateral ground reaction forces. Increasing the attack angle with a constant leg stiffness results in a higher step frequency, a decrease in the step length, an increase in the total energy of the system and a decrease in both the peak vertical and lateral ground reaction forces.

  5. Scaling of Quantum Walks on Complex Networks

    NASA Astrophysics Data System (ADS)

    Boettcher, Stefan; Falkner, Stefan; Portugal, Renato

    2015-03-01

    I will describe the renormalization group method (RG) as applied to master equations with a unitary propagator. It allows to determine many asymptotic properties of quantum walks, although I will focus here on the walk dimension dw, which describes the similarity solution, ? (x , t) ~ f| x | dw / t , for the probability density function ?. We can calculate dw to arbitrary accuracy for a number of networks, such as the dual Sierpinksi gasket, small-world Hanoi networks, or Migdal-Kadanoff lattices, which we have verified with direct simulations. However, due to unitarity, the asymptotic solution of the RG equations as well as procedures to implement RG approximately for arbitrary networks remain elusive. Yet, based on the exact RG for those fractal networks, we can conjecture a few general conclusions, for instance, that dw for a discrete-time quantum walk is always half of that for the random walk on the same r-regular network, when driven with the Grover coin. (This talk summarizes our work in http://dx.doi.org/10.1103/PhysRevA.90.032324 and http://arxiv.org/abs/1410.7034.) We acknowledge financial support from the U.S. National Science Foundation through Grant DMR-1207431.

  6. The walk and jump of Equisetum spores.

    PubMed

    Marmottant, Philippe; Ponomarenko, Alexandre; Bienaimé, Diane

    2013-11-01

    Equisetum plants (horsetails) reproduce by producing tiny spherical spores that are typically 50 µm in diameter. The spores have four elaters, which are flexible ribbon-like appendages that are initially wrapped around the main spore body and that deploy upon drying or fold back in humid air. If elaters are believed to help dispersal, the exact mechanism for spore motion remains unclear in the literature. In this manuscript, we present observations of the 'walks' and 'jumps' of Equisetum spores, which are novel types of spore locomotion mechanisms compared to the ones of other spores. Walks are driven by humidity cycles, each cycle inducing a small step in a random direction. The dispersal range from the walk is limited, but the walk provides key steps to either exit the sporangium or to reorient and refold. Jumps occur when the spores suddenly thrust themselves after being tightly folded. They result in a very efficient dispersal: even spores jumping from the ground can catch the wind again, whereas non-jumping spores stay on the ground. The understanding of these movements, which are solely driven by humidity variations, conveys biomimetic inspiration for a new class of self-propelled objects. PMID:24026816

  7. Go Naked: Diapers Affect Infant Walking

    ERIC Educational Resources Information Center

    Cole, Whitney G.; Lingeman, Jesse M.; Adolph, Karen E.

    2012-01-01

    In light of cross-cultural and experimental research highlighting effects of childrearing practices on infant motor skill, we asked whether wearing diapers, a seemingly innocuous childrearing practice, affects infant walking. Diapers introduce bulk between the legs, potentially exacerbating infants' poor balance and wide stance. We show that…

  8. Exotic states of bouncing and walking droplets

    NASA Astrophysics Data System (ADS)

    Wind-Willassen, istein; Mol?ek, Jan; Harris, Daniel M.; Bush, John W. M.

    2013-08-01

    We present the results of an integrated experimental and theoretical investigation of droplets bouncing on a vibrating fluid bath. A comprehensive series of experiments provides the most detailed characterisation to date of the system's dependence on fluid properties, droplet size, and vibrational forcing. A number of new bouncing and walking states are reported, including complex periodic and aperiodic motions. Particular attention is given to the first characterisation of the different gaits arising within the walking regime. In addition to complex periodic walkers and limping droplets, we highlight a previously unreported mixed state, in which the droplet switches periodically between two distinct walking modes. Our experiments are complemented by a theoretical study based on our previous developments [J. Molacek and J. W. M. Bush, J. Fluid Mech. 727, 582-611 (2013);, 10.1017/jfm.2013.279 J. Molacek and J. W. M. Bush, J. Fluid Mech. 727, 612-647 (2013)], 10.1017/jfm.2013.280, which provide a basis for rationalising all observed bouncing and walking states.

  9. Sunspot random walk and 22-year variation

    USGS Publications Warehouse

    Love, Jeffrey J.; Rigler, E. Joshua

    2012-01-01

    We examine two stochastic models for consistency with observed long-term secular trends in sunspot number and a faint, but semi-persistent, 22-yr signal: (1) a null hypothesis, a simple one-parameter random-walk model of sunspot-number cycle-to-cycle change, and, (2) an alternative hypothesis, a two-parameter random-walk model with an imposed 22-yr alternating amplitude. The observed secular trend in sunspots, seen from solar cycle 5 to 23, would not be an unlikely result of the accumulation of multiple random-walk steps. Statistical tests show that a 22-yr signal can be resolved in historical sunspot data; that is, the probability is low that it would be realized from random data. On the other hand, the 22-yr signal has a small amplitude compared to random variation, and so it has a relatively small effect on sunspot predictions. Many published predictions for cycle 24 sunspots fall within the dispersion of previous cycle-to-cycle sunspot differences. The probability is low that the Sun will, with the accumulation of random steps over the next few cycles, walk down to a Dalton-like minimum. Our models support published interpretations of sunspot secular variation and 22-yr variation resulting from cycle-to-cycle accumulation of dynamo-generated magnetic energy.

  10. A Random Walk on a Circular Path

    ERIC Educational Resources Information Center

    Ching, W.-K.; Lee, M. S.

    2005-01-01

    This short note introduces an interesting random walk on a circular path with cards of numbers. By using high school probability theory, it is proved that under some assumptions on the number of cards, the probability that a walker will return to a fixed position will tend to one as the length of the circular path tends to infinity.

  11. Random Walk Method for Potential Problems

    NASA Technical Reports Server (NTRS)

    Krishnamurthy, T.; Raju, I. S.

    2002-01-01

    A local Random Walk Method (RWM) for potential problems governed by Lapalace's and Paragon's equations is developed for two- and three-dimensional problems. The RWM is implemented and demonstrated in a multiprocessor parallel environment on a Beowulf cluster of computers. A speed gain of 16 is achieved as the number of processors is increased from 1 to 23.

  12. Go Naked: Diapers Affect Infant Walking

    ERIC Educational Resources Information Center

    Cole, Whitney G.; Lingeman, Jesse M.; Adolph, Karen E.

    2012-01-01

    In light of cross-cultural and experimental research highlighting effects of childrearing practices on infant motor skill, we asked whether wearing diapers, a seemingly innocuous childrearing practice, affects infant walking. Diapers introduce bulk between the legs, potentially exacerbating infants' poor balance and wide stance. We show that

  13. The Physics of a Walking Robot

    ERIC Educational Resources Information Center

    Guemez, J.; Fiolhais, M.

    2013-01-01

    The physics of walking is explored, using a toy as a concrete example and a "toy model" applied to it. Besides using Newton's second law, the problem is also discussed from the thermodynamical perspective. Once the steady state (constant velocity) is achieved, we show that the internal energy of the toy is dissipated as heat in the…

  14. Assessment of a Solar System Walk

    ERIC Educational Resources Information Center

    LoPresto, Michael C.; Murrell, Steven R.; Kirchner, Brian

    2010-01-01

    The idea of sending students and the general public on a walk through a scale model of the solar system in an attempt to instill an appreciation of the relative scales of the sizes of the objects compared to the immense distances between them is certainly not new. A good number of such models exist, including one on the National Mall in…

  15. Searching via walking: How to find a marked clique of a complete graph using quantum walks

    SciTech Connect

    Hillery, Mark; Reitzner, Daniel; Buzek, Vladimir

    2010-06-15

    We show how a quantum walk can be used to find a marked edge or a marked complete subgraph of a complete graph. We employ a version of a quantum walk, the scattering walk, which lends itself to experimental implementation. The edges are marked by adding elements to them that impart a specific phase shift to the particle as it enters or leaves the edge. If the complete graph has N vertices and the subgraph has K vertices, the particle becomes localized on the subgraph in O(N/K) steps. This leads to a quantum search that is quadratically faster than a corresponding classical search. We show how to implement the quantum walk using a quantum circuit and a quantum oracle, which allows us to specify the resources needed for a quantitative comparison of the efficiency of classical and quantum searches--the number of oracle calls.

  16. Accumulating Brisk Walking for Fitness, Cardiovascular Risk, and Psychological Health.

    ERIC Educational Resources Information Center

    Murphy, Marie; Nevill, Alan; Neville, Charlotte; Biddle, Stuart; Hardman, Adrianne

    2002-01-01

    Compared the effects of different patterns of regular brisk walking on fitness, cardiovascular disease risk factors, and psychological well-being in previously sedentary adults. Data on adults who completed either short-bout or long-bout walking programs found that three short bouts of brisk walking accumulated throughout the day were as effective

  17. The Not-so-Random Drunkard's Walk

    ERIC Educational Resources Information Center

    Ehrhardt, George

    2013-01-01

    This dataset contains the results of a quasi-experiment, testing Karl Pearson's "drunkard's walk" analogy for an abstract random walk. Inspired by the alternate hypothesis that drunkards stumble to the side of their dominant hand, it includes data on intoxicated test subjects walking a 10' line. Variables include: the…

  18. Random Walks Systems with Finite Lifetime on Z

    NASA Astrophysics Data System (ADS)

    Lebensztayn, Elcio; Machado, Fbio Prates; Martinez, Mauricio Zuluaga

    2016-02-01

    We consider a non-homogeneous random walks system on Z in which each active particle performs a nearest neighbor random walk and activates all inactive particles it encounters up to a total amount of L jumps. We present necessary and sufficient conditions for the process to survive, which means that an infinite number of random walks become activated.

  19. The Walking Classroom: Active Learning Is Just Steps Away!

    ERIC Educational Resources Information Center

    Becker, Kelly Mancini

    2016-01-01

    Walking is a viable and valuable form of exercise for young children that has both physical and mental health benefits. There is much evidence showing that school-age children are not getting the recommended 60 minutes of daily exercise. A school-wide walking program can be a great way to encourage walking in and out of school, can be aligned with…

  20. The Walking Classroom: Active Learning Is Just Steps Away!

    ERIC Educational Resources Information Center

    Becker, Kelly Mancini

    2016-01-01

    Walking is a viable and valuable form of exercise for young children that has both physical and mental health benefits. There is much evidence showing that school-age children are not getting the recommended 60 minutes of daily exercise. A school-wide walking program can be a great way to encourage walking in and out of school, can be aligned with

  1. The Not-so-Random Drunkard's Walk

    ERIC Educational Resources Information Center

    Ehrhardt, George

    2013-01-01

    This dataset contains the results of a quasi-experiment, testing Karl Pearson's "drunkard's walk" analogy for an abstract random walk. Inspired by the alternate hypothesis that drunkards stumble to the side of their dominant hand, it includes data on intoxicated test subjects walking a 10' line. Variables include: the

  2. A natural walking monitor for pulmonary patients using mobile phones.

    PubMed

    Juen, Joshua; Cheng, Qian; Schatz, Bruce

    2015-07-01

    Mobile devices have the potential to continuously monitor health by collecting movement data including walking speed during natural walking. Natural walking is walking without artificial speed constraints present in both treadmill and nurse-assisted walking. Fitness trackers have become popular which record steps taken and distance, typically using a fixed stride length. While useful for everyday purposes, medical monitoring requires precise accuracy and testing on real patients with a scientifically valid measure. Walking speed is closely linked to morbidity in patients and widely used for medical assessment via measured walking. The 6-min walk test (6MWT) is a standard assessment for chronic obstructive pulmonary disease and congestive heart failure. Current generation smartphone hardware contains similar sensor chips as in medical devices and popular fitness devices. We developed a middleware software, MoveSense, which runs on standalone smartphones while providing comparable readings to medical accelerometers. We evaluate six machine learning methods to obtain gait speed during natural walking training models to predict natural walking speed and distance during a 6MWT with 28 pulmonary patients and ten subjects without pulmonary condition. We also compare our model's accuracy to popular fitness devices. Our universally trained support vector machine models produce 6MWT distance with 3.23% error during a controlled 6MWT and 11.2% during natural free walking. Furthermore, our model attains 7.9% error when tested on five subjects for distance estimation compared to the 50-400% error seen in fitness devices during natural walking. PMID:25935052

  3. Exploring Muscle Activation during Nordic Walking: A Comparison between Conventional and Uphill Walking.

    PubMed

    Pellegrini, Barbara; Peyr-Tartaruga, Leonardo Alexandre; Zoppirolli, Chiara; Bortolan, Lorenzo; Bacchi, Elisabetta; Figard-Fabre, Hlne; Schena, Federico

    2015-01-01

    Nordic Walking (NW) owes much of its popularity to the benefits of greater energy expenditure and upper body engagement than found in conventional walking (W). Muscle activation during NW is still understudied, however. The aim of the present study was to assess differences in muscle activation and physiological responses between NW and W in level and uphill walking conditions. Nine expert Nordic Walkers (mean age 36.811.9 years; BMI 24.21.8 kg/m2) performed 5-minute treadmill trials of W and NW at 4 km/h on inclines of 0% and 15%. The electromyographic activity of seven upper body and five leg muscles and oxygen consumption (VO2) were recorded and pole force during NW was measured. VO2 during NW was 22.3% higher at 0% and only 6.9% higher at 15% than during W, while upper body muscle activation was 2- to 15-fold higher under both conditions. Lower body muscle activation was similarly increased during NW and W in the uphill condition, whereas the increase in erector spinae muscle activity was lower during NW than W. The lack of a significant increase in pole force during uphill walking may explain the lower extra energy expenditure of NW, indicating less upper body muscle activation to lift the body against gravity. NW seemed to reduce lower back muscle contraction in the uphill condition, suggesting that walking with poles may reduce effort to control trunk oscillations and could contribute to work production during NW. Although the difference in extra energy expenditure between NW and W was smaller in the uphill walking condition, the increased upper body muscle involvement during exercising with NW may confer additional benefit compared to conventional walking also on uphill terrains. Furthermore, people with low back pain may gain benefit from pole use when walking uphill. PMID:26418339

  4. Walk Test Used to Monitor the Performance in the Health-Directed Nordic Walking

    ERIC Educational Resources Information Center

    Kamien, Dorota

    2008-01-01

    Study aim: To assess the performance of subjects engaged in health-directed Nordic Walking training (with poles) and subjected to 2-km walk test (no poles). Material and methods: A total of 72 subjects, including 8 men and 32 women aged 23-73 years and 32 female students aged 19-25 years participated in the study. They were subjected twice to 2-km

  5. Exploring Muscle Activation during Nordic Walking: A Comparison between Conventional and Uphill Walking

    PubMed Central

    Pellegrini, Barbara; Peyré-Tartaruga, Leonardo Alexandre; Zoppirolli, Chiara; Bortolan, Lorenzo; Bacchi, Elisabetta; Figard-Fabre, Hélène; Schena, Federico

    2015-01-01

    Nordic Walking (NW) owes much of its popularity to the benefits of greater energy expenditure and upper body engagement than found in conventional walking (W). Muscle activation during NW is still understudied, however. The aim of the present study was to assess differences in muscle activation and physiological responses between NW and W in level and uphill walking conditions. Nine expert Nordic Walkers (mean age 36.8±11.9 years; BMI 24.2±1.8 kg/m2) performed 5-minute treadmill trials of W and NW at 4 km/h on inclines of 0% and 15%. The electromyographic activity of seven upper body and five leg muscles and oxygen consumption (VO2) were recorded and pole force during NW was measured. VO2 during NW was 22.3% higher at 0% and only 6.9% higher at 15% than during W, while upper body muscle activation was 2- to 15-fold higher under both conditions. Lower body muscle activation was similarly increased during NW and W in the uphill condition, whereas the increase in erector spinae muscle activity was lower during NW than W. The lack of a significant increase in pole force during uphill walking may explain the lower extra energy expenditure of NW, indicating less upper body muscle activation to lift the body against gravity. NW seemed to reduce lower back muscle contraction in the uphill condition, suggesting that walking with poles may reduce effort to control trunk oscillations and could contribute to work production during NW. Although the difference in extra energy expenditure between NW and W was smaller in the uphill walking condition, the increased upper body muscle involvement during exercising with NW may confer additional benefit compared to conventional walking also on uphill terrains. Furthermore, people with low back pain may gain benefit from pole use when walking uphill. PMID:26418339

  6. [Comparison of kinematic and kinetic parameters between the locomotion patterns in nordic walking, walking and running].

    PubMed

    Kleindienst, F I; Michel, K J; Schwarz, J; Krabbe, B

    2006-03-01

    Based on a higher cardio-pulmonary and cardio-vascular benefit and a promised reduction of mechanical load of the musculoskeletal system Nordic Walking (NW) shows an increased market potential. The present study should investigate whether there are biomechanical differences between the locomotion patterns NW, walking and running. Moreover possible resultant load differences should be determined. Eleven subjects, who were already experienced with the NW-technique, participated in this experiment. The kinematic data were collected using two high-speed camera systems from posterior and from lateral at the same time. Simultaneously the ground reaction forces were recorded. The kinematic and the kinetic data reveal differences between the three analyzed locomotion patterns. For NW as well as walking the mechanical load of the lower extremity is lower compared to running. None of the kinematic parameters suggest a "physiological benefit" of NW compared to walking. Moreover NW shows higher vertical and horizontal forces during landing. Exclusively the lower vertical force peak during push off indicates a lower mechanical load for NW in comparison to walking. Consequently it is questionable is NW -- based on its promised "biomechanical benefits" compared to walking -- should be still recommended for overweight people and for people with existing musculoskeletal problems of the lower limb. PMID:16544213

  7. Universal quantum computation using the discrete-time quantum walk

    SciTech Connect

    Lovett, Neil B.; Cooper, Sally; Everitt, Matthew; Trevers, Matthew; Kendon, Viv

    2010-04-15

    A proof that continuous-time quantum walks are universal for quantum computation, using unweighted graphs of low degree, has recently been presented by A. M. Childs [Phys. Rev. Lett. 102, 180501 (2009)]. We present a version based instead on the discrete-time quantum walk. We show that the discrete-time quantum walk is able to implement the same universal gate set and thus both discrete and continuous-time quantum walks are computational primitives. Additionally, we give a set of components on which the discrete-time quantum walk provides perfect state transfer.

  8. One-dimensional lazy quantum walks and occupancy rate

    NASA Astrophysics Data System (ADS)

    Li, Dan; Michael, McGettrick; Zhang, Wei-Wei; Zhang, Ke-Jia

    2015-05-01

    In this paper, we discuss the properties of lazy quantum walks. Our analysis shows that the lazy quantum walks have O(tn) order of the n-th moment of the corresponding probability distribution, which is the same as that for normal quantum walks. The lazy quantum walk with a discrete Fourier transform (DFT) coin operator has a similar probability distribution concentrated interval to that of the normal Hadamard quantum walk. Most importantly, we introduce the concepts of occupancy number and occupancy rate to measure the extent to which the walk has a (relatively) high probability at every position in its range. We conclude that the lazy quantum walks have a higher occupancy rate than other walks such as normal quantum walks, classical walks, and lazy classical walks. Project supported by the National Natural Science Foundation of China (Grant Nos. 61272057 and 61170270), the Higher Education Young Elite Teacher Project of Beijing, China (Grant No. YETP0475 and YETP0477), the BUPT Excellent Ph. D. Students Foundation (Grant Nos. CX201325 and CX201326), and the China Scholarship Council (Grant No. 201306470046).

  9. Step length and required friction in walking.

    PubMed

    Cooper, Ryan C; Prebeau-Menezes, Leif M; Butcher, Michael T; Bertram, John E A

    2008-05-01

    The effect of step length on minimum required coefficient of friction (microR) during a walking step was isolated from other features that influence the mechanics of foot contact (such as speed). Ground reaction force (GRF) from defined step lengths at consistent forward speed was used to calculate (microR), required coefficent of friction. Some individuals walked in a manner that generated a (microR) that was 50% larger than others, in spite of being restricted to the same speed, step length and step frequency. Unshod subjects had greater (microR) compared to shod subjects except at the shortest step lengths. Understanding the dynamic interaction of applied vertical and horizontal forces is necessary to develop strategies to effectively evaluate unsafe circumstances, or modify behavior and develop safer equipment (at home and/or in the workplace) to deal with adverse footing environments. PMID:17703942

  10. Conifer-Derived Monoterpenes and Forest Walking

    PubMed Central

    Sumitomo, Kazuhiro; Akutsu, Hiroaki; Fukuyama, Syusei; Minoshima, Akiho; Kukita, Shin; Yamamura, Yuji; Sato, Yoshiaki; Hayasaka, Taiki; Osanai, Shinobu; Funakoshi, Hiroshi; Hasebe, Naoyuki; Nakamura, Masao

    2015-01-01

    Conifer and broadleaf trees emit volatile organic compounds in the summer. The major components of these emissions are volatile monoterpenes. Using solid phase microextraction fiber as the adsorbant, monoterpenes were successfully detected and identified in forest air samples. Gas chromatography/mass chromatogram of monoterpenes in the atmosphere of a conifer forest and that of serum from subjects who were walking in a forest were found to be similar each other. The amounts of α-pinene in the subjects became several folds higher after forest walking. The results indicate that monoterpenes in the atmosphere of conifer forests are transferred to and accumulate in subjects by inhalation while they are exposed to this type of environment. PMID:26819913

  11. Random walks on finite lattices with traps

    NASA Astrophysics Data System (ADS)

    Hatlee, Michael D.; Kozak, John J.

    1980-02-01

    We consider dissipative processes involving both chemical reaction and physical diffusion in systems for which the influence of boundaries and system size on the dynamics cannot be neglected. We report the results of Monte Carlo simulations on an irreversible reaction in a confined system subject to two sorts of finite boundary conditions. The problem is posed in such a way as to take maximal advantage of two earlier studies: Montroll's work on random walks on d-dimensional periodic lattices with traps, and the work of Sanders, Ruijgrok, and ten Bosch on random walks on two-dimensional finite lattices with traps. Our results are used to discuss the concept of reduction of dimensionality as introduced by Adam and Delbrck in their study of biological diffusion processes.

  12. Generalized ruin problems and asynchronous random walks

    NASA Astrophysics Data System (ADS)

    Abad, E.

    2005-07-01

    We consider a gambling game with two different kinds of trials and compute the duration of the game (averaged over all possible initial capitals of the players) by a mapping of the problem to a 1D lattice walk of two particles reacting upon encounter. The relative frequency of the trials is governed by the synchronicity parameter p of the random walk. The duration of the game is given by the mean time to reaction, which turns out to display a different behavior for even and odd lattices, i.e. this quantity is monotonic in p for odd lattices and non-monotonic for even lattices. In the game picture, this implies that the players minimize the duration of the game by restricting themselves to one type of trial if their joint capital is odd, otherwise a non-symmetric mixture of both trials is needed.

  13. An invariance property of diffusive random walks

    NASA Astrophysics Data System (ADS)

    Blanco, S.; Fournier, R.

    2003-01-01

    Starting from a simple animal-biology example, a general, somewhat counter-intuitive property of diffusion random walks is presented. It is shown that for any (non-homogeneous) purely diffusing system, under any isotropic uniform incidence, the average length of trajectories through the system (the average length of the random walk trajectories from entry point to first exit point) is independent of the characteristics of the diffusion process and therefore depends only on the geometry of the system. This exact invariance property may be seen as a generalization to diffusion of the well-known mean-chord-length property (Case K. M. and Zweifel P. F., Linear Transport Theory (Addison-Wesley) 1967), leading to broad physics and biology applications.

  14. Fractal landscape analysis of DNA walks

    NASA Astrophysics Data System (ADS)

    Peng, C.-K.; Buldyrev, S. V.; Goldberger, A. L.; Havlin, S.; Sciortino, F.; Simons, M.; Stanley, H. E.

    1992-12-01

    By mapping nucleotide sequences onto a DNA walk, we uncovered remarkably long-range power law correlations [Nature 356 (1992) 168] that simply a new scale invariant property of DNA. We found such long-range correlations in intron-containing genes and in non-transcribed regulatory DNA sequences, but not in cDNA sequences or intron-less genes. In this paper, we present more explicit evidences to support our findings.

  15. Walking Habits of Adults with Mental Retardation

    ERIC Educational Resources Information Center

    Stanish, Heidi I.; Draheim, Christopher C.

    2005-01-01

    The walking activity of men and women with mental retardation residing in community settings was described. Participants were 38 women (M age = 0.7, SD = 9.5) and 65 men (M age = 35.9, SD = 11.2). They wore pedometers for 7 days. A 2 ? 2 factorial ANOVA indicated no significant gender differences in total step counts or between participants with

  16. Fractal landscape analysis of DNA walks

    NASA Technical Reports Server (NTRS)

    Peng, C. K.; Buldyrev, S. V.; Goldberger, A. L.; Havlin, S.; Sciortino, F.; Simons, M.; Stanley, H. E.

    1992-01-01

    By mapping nucleotide sequences onto a "DNA walk", we uncovered remarkably long-range power law correlations [Nature 356 (1992) 168] that imply a new scale invariant property of DNA. We found such long-range correlations in intron-containing genes and in non-transcribed regulatory DNA sequences, but not in cDNA sequences or intron-less genes. In this paper, we present more explicit evidences to support our findings.

  17. A Random Walk Picture of Basketball

    NASA Astrophysics Data System (ADS)

    Gabel, Alan; Redner, Sidney

    2012-02-01

    We analyze NBA basketball play-by-play data and found that scoring is well described by a weakly-biased, anti-persistent, continuous-time random walk. The time between successive scoring events follows an exponential distribution, with little memory between events. We account for a wide variety of statistical properties of scoring, such as the distribution of the score difference between opponents and the fraction of game time that one team is in the lead.

  18. Movement patterns of Tenebrio beetles demonstrate empirically that correlated-random-walks have similitude with a Lvy walk.

    PubMed

    Reynolds, Andy M; Leprtre, Lisa; Bohan, David A

    2013-01-01

    Correlated random walks are the dominant conceptual framework for modelling and interpreting organism movement patterns. Recent years have witnessed a stream of high profile publications reporting that many organisms perform Lvy walks; movement patterns that seemingly stand apart from the correlated random walk paradigm because they are discrete and scale-free rather than continuous and scale-finite. Our new study of the movement patterns of Tenebrio molitor beetles in unchanging, featureless arenas provides the first empirical support for a remarkable and deep theoretical synthesis that unites correlated random walks and Lvy walks. It demonstrates that the two models are complementary rather than competing descriptions of movement pattern data and shows that correlated random walks are a part of the Lvy walk family. It follows from this that vast numbers of Lvy walkers could be hiding in plain sight. PMID:24196232

  19. 'It was not just a walking experience': reflections on the role of care in dog-walking.

    PubMed

    Degeling, Chris; Rock, Melanie

    2013-09-01

    Research into physical activity and human health has recently begun to attend to dog-walking. This study extends the literature on dog-walking as a health behaviour by conceptualizing dog-walking as a caring practice. It centres on qualitative interviews with 11 Canadian dog-owners. All participants resided in urban neighbourhoods identified through previous quantitative research as conducive to dog-walking. Canine characteristics, including breed and age, were found to influence people's physical activity. The health of the dog and its position in the life-course influenced patterns of dog-walking. Frequency, duration and spatial patterns of dog-walking all depended on relationships and people's capacity to tap into resources. In foregrounding networks of care, inclusive of pets and public spaces, a relational conceptualization of dog-walking as a practice of caring helps to make sense of heterogeneity in patterns of physical activity among dog-owners. PMID:22752107

  20. Genome Walking by Next Generation Sequencing Approaches

    PubMed Central

    Volpicella, Mariateresa; Leoni, Claudia; Costanza, Alessandra; Fanizza, Immacolata; Placido, Antonio; Ceci, Luigi R.

    2012-01-01

    Genome Walking (GW) comprises a number of PCR-based methods for the identification of nucleotide sequences flanking known regions. The different methods have been used for several purposes: from de novo sequencing, useful for the identification of unknown regions, to the characterization of insertion sites for viruses and transposons. In the latter cases Genome Walking methods have been recently boosted by coupling to Next Generation Sequencing technologies. This review will focus on the development of several protocols for the application of Next Generation Sequencing (NGS) technologies to GW, which have been developed in the course of analysis of insertional libraries. These analyses find broad application in protocols for functional genomics and gene therapy. Thanks to the application of NGS technologies, the original vision of GW as a procedure for walking along an unknown genome is now changing into the possibility of observing the parallel marching of hundreds of thousands of primers across the borders of inserted DNA molecules in host genomes. PMID:24832505

  1. From Lvy walks to superdiffusive shock acceleration

    SciTech Connect

    Zimbardo, Gaetano; Perri, Silvia E-mail: silvia.perri@fis.unical.it

    2013-11-20

    In this paper, we present a general scenario for nondiffusive transport and we investigate the influence of anomalous, superdiffusive transport on Fermi acceleration processes at shocks. We explain why energetic particle superdiffusion can be described within the Lvy walk framework, which is based on a power-law distribution of free path lengths and on a coupling between free path length and free path duration. A self-contained derivation of the particle mean square displacement, which grows as (?x {sup 2}) = 2D {sub ?} t {sup ?} with ? > 1, and the particle propagator, is presented for Lvy walks, making use of a generalized version of the Montroll-Weiss equation. We also derive for the first time an explicit expression for the anomalous diffusion coefficient D {sub ?} and we discuss how to obtain these quantities from energetic particle observations in space. The results are applied to the case of particle acceleration at an infinite planar shock front. Using the scaling properties of the Lvy walk propagator, the energy spectral indices are found to have values smaller than the ones predicted by the diffusive shock acceleration theory. Furthermore, when applying the results to ions with energies of a few MeV accelerated at the solar wind termination shock, the estimation of the anomalous diffusion coefficient associated with the superdiffusive motion gives acceleration times much smaller than the ones related to normal diffusion.

  2. Integrated system for single leg walking

    NASA Astrophysics Data System (ADS)

    Simmons, Reid; Krotkov, Eric; Roston, Gerry

    1990-07-01

    The Carnegie Mellon University Planetary Rover project is developing a six-legged walking robot capable of autonomously navigating, exploring, and acquiring samples in rugged, unknown environments. This report describes an integrated software system capable of navigating a single leg of the robot over rugged terrain. The leg, based on an early design of the Ambler Planetary Rover, is suspended below a carriage that slides along rails. To walk, the system creates an elevation map of the terrain from laser scanner images, plans an appropriate foothold based on terrain and geometric constraints, weaves the leg through the terrain to position it above the foothold, contacts the terrain with the foot, and applies force enough to advance the carriage along the rails. Walking both forward and backward, the system has traversed hundreds of meters of rugged terrain including obstacles too tall to step over, trenches too deep to step in, closely spaced obstacles, and sand hills. The implemented system consists of a number of task-specific processes (two for planning, two for perception, one for real-time control) and a central control process that directs the flow of communication between processes.

  3. Leg asymmetries and coordination dynamics in walking.

    PubMed

    Russell, Daniel M; Kalbach, Clint R; Massimini, Christopher M; Martinez-Garza, Cesar

    2010-01-01

    Models of interlimb coordination (H. Haken, J. A. S. Kelso, & H. Bunz, 1985; P. N. Kugler & M. T. Turvey, 1987) were tested in walking by examining the role of asymmetries between limbs. Participants walked on a treadmill with and without a metronome. Five asymmetry conditions were created via ankle loads of 0, 3, or 6 kg on either leg. With the metronome, participants matched the target period. Without the metronome, stride rate slowed as the mass was increased on either leg. The loads led to an increase in stride period that was predicted by Huygens' law and the hybrid pendulum-spring model. In agreement with extended Haken-Kelso-Bunz model predictions, leg asymmetries led to deviations from antiphase coordination. Also, perception-action coordination was influenced by the asymmetry between the legs and metronome. In contrast, no predicted stability effects were observed. These findings reveal that some properties of interlimb coordination, apparent in laboratory-based tasks, can also be observed in human walking. PMID:20363714

  4. From Lvy Walks to Superdiffusive Shock Acceleration

    NASA Astrophysics Data System (ADS)

    Zimbardo, Gaetano; Perri, Silvia

    2013-11-01

    In this paper, we present a general scenario for nondiffusive transport and we investigate the influence of anomalous, superdiffusive transport on Fermi acceleration processes at shocks. We explain why energetic particle superdiffusion can be described within the Lvy walk framework, which is based on a power-law distribution of free path lengths and on a coupling between free path length and free path duration. A self-contained derivation of the particle mean square displacement, which grows as lang?x 2rang = 2D ? t ? with ? > 1, and the particle propagator, is presented for Lvy walks, making use of a generalized version of the Montroll-Weiss equation. We also derive for the first time an explicit expression for the anomalous diffusion coefficient D ? and we discuss how to obtain these quantities from energetic particle observations in space. The results are applied to the case of particle acceleration at an infinite planar shock front. Using the scaling properties of the Lvy walk propagator, the energy spectral indices are found to have values smaller than the ones predicted by the diffusive shock acceleration theory. Furthermore, when applying the results to ions with energies of a few MeV accelerated at the solar wind termination shock, the estimation of the anomalous diffusion coefficient associated with the superdiffusive motion gives acceleration times much smaller than the ones related to normal diffusion.

  5. The walk and jump of Equisetum spores

    PubMed Central

    Marmottant, Philippe; Ponomarenko, Alexandre; Bienaimé, Diane

    2013-01-01

    Equisetum plants (horsetails) reproduce by producing tiny spherical spores that are typically 50 µm in diameter. The spores have four elaters, which are flexible ribbon-like appendages that are initially wrapped around the main spore body and that deploy upon drying or fold back in humid air. If elaters are believed to help dispersal, the exact mechanism for spore motion remains unclear in the literature. In this manuscript, we present observations of the ‘walks’ and ‘jumps’ of Equisetum spores, which are novel types of spore locomotion mechanisms compared to the ones of other spores. Walks are driven by humidity cycles, each cycle inducing a small step in a random direction. The dispersal range from the walk is limited, but the walk provides key steps to either exit the sporangium or to reorient and refold. Jumps occur when the spores suddenly thrust themselves after being tightly folded. They result in a very efficient dispersal: even spores jumping from the ground can catch the wind again, whereas non-jumping spores stay on the ground. The understanding of these movements, which are solely driven by humidity variations, conveys biomimetic inspiration for a new class of self-propelled objects. PMID:24026816

  6. 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

  7. Modulation of Head Movement Control During Walking

    NASA Technical Reports Server (NTRS)

    Mulavara, Ajitkumar P.; Verstraete, Mary C.; Bloomberg, Jacob J.; Paloski, William H. (Technical Monitor)

    1999-01-01

    The purpose of this study was to investigate the coordination of the head relative to the trunk within a gait cycle during gaze fixation. Nine normal subjects walked on a motorized treadmill driven at 1.79 m/sec (20 s trials) while fixing their gaze on a centrally located earth-fixed target positioned at a distance of 2m from their eyes. The relative motion of the head and the net torque acting on it relative to the trunk during the gait cycle were used as measures of coordination. It was found that the net torque applied to the head counteracts the destabilizing forces acting on the upper body during locomotion. The average net torque impulse was significantly different (p less than 0.05) between the heel strike and swing phases and were found to be symmetrical between the right and left leg events of the gait cycle. However, the average net displacement of the head relative to the trunk was maintained uniform (p greater than 0.05) throughout the gait cycle. Thus, the coordination of the motion of the head relative to the trunk during walking is dynamically modulated depending on the behavioral events occurring in the gait cycle. This modulation may serve to aid stabilization of the head by counteracting the force variations acting on the upper body that may aid in the visual fixing of targets during walking.

  8. Random walks on generalized Koch networks

    NASA Astrophysics Data System (ADS)

    Sun, Weigang

    2013-10-01

    For deterministically growing networks, it is a theoretical challenge to determine the topological properties and dynamical processes. In this paper, we study random walks on generalized Koch networks with features that include an initial state that is a globally connected network to r nodes. In each step, every existing node produces m complete graphs. We then obtain the analytical expressions for first passage time (FPT), average return time (ART), i.e. the average of FPTs for random walks from node i to return to the starting point i for the first time, and average sending time (AST), defined as the average of FPTs from a hub node to all other nodes, excluding the hub itself with regard to network parameters m and r. For this family of Koch networks, the ART of the new emerging nodes is identical and increases with the parameters m or r. In addition, the AST of our networks grows with network size N as N?ln?N and also increases with parameter m. The results obtained in this paper are the generalizations of random walks for the original Koch network.

  9. Walking for Well-Being: Are Group Walks in Certain Types of Natural Environments Better for Well-Being than Group Walks in Urban Environments?

    PubMed Central

    Marselle, Melissa R.; Irvine, Katherine N.; Warber, Sara L.

    2013-01-01

    The benefits of walking in natural environments for well-being are increasingly understood. However, less well known are the impacts different types of natural environments have on psychological and emotional well-being. This cross-sectional study investigated whether group walks in specific types of natural environments were associated with greater psychological and emotional well-being compared to group walks in urban environments. Individuals who frequently attended a walking group once a week or more (n = 708) were surveyed on mental well-being (Warwick Edinburgh Mental Well-being Scale), depression (Major Depressive Inventory), perceived stress (Perceived Stress Scale) and emotional well-being (Positive and Negative Affect Schedule). Compared to group walks in urban environments, group walks in farmland were significantly associated with less perceived stress and negative affect, and greater mental well-being. Group walks in green corridors were significantly associated with less perceived stress and negative affect. There were no significant differences between the effect of any environment types on depression or positive affect. Outdoor walking group programs could be endorsed through “green prescriptions” to improve psychological and emotional well-being, as well as physical activity. PMID:24173142

  10. Walks4work: Rationale and study design to investigate walking at lunchtime in the workplace setting

    PubMed Central

    2012-01-01

    Background Following recruitment of a private sector company, an 8?week lunchtime walking intervention was implemented to examine the effect of the intervention on modifiable cardiovascular disease risk factors, and further to see if walking environment had any further effect on the cardiovascular disease risk factors. Methods For phase 1 of the study participants were divided into three groups, two lunchtime walking intervention groups to walk around either an urban or natural environment twice a week during their lunch break over an 8?week period. The third group was a waiting-list control who would be invited to join the walking groups after phase 1. In phase 2 all participants were encouraged to walk during their lunch break on self-selecting routes. Health checks were completed at baseline, end of phase 1 and end of phase 2 in order to measure the impact of the intervention on cardiovascular disease risk. The primary outcome variables of heart rate and heart rate variability were measured to assess autonomic function associated with cardiovascular disease. Secondary outcome variables (Body mass index, blood pressure, fitness, autonomic response to a stressor) related to cardiovascular disease were also measured. The efficacy of the intervention in increasing physical activity was objectively monitored throughout the 8-weeks using an accelerometer device. Discussion The results of this study will help in developing interventions with low researcher input with high participant output that may be implemented in the workplace. If effective, this study will highlight the contribution that natural environments can make in the reduction of modifiable cardiovascular disease risk factors within the workplace. PMID:22830646

  11. Optimal speeds for walking and running, and walking on a moving walkway.

    PubMed

    Srinivasan, Manoj

    2009-06-01

    Many aspects of steady human locomotion are thought to be constrained by a tendency to minimize the expenditure of metabolic cost. This paper has three parts related to the theme of energetic optimality: (1) a brief review of energetic optimality in legged locomotion, (2) an examination of the notion of optimal locomotion speed, and (3) an analysis of walking on moving walkways, such as those found in some airports. First, I describe two possible connotations of the term "optimal locomotion speed:" that which minimizes the total metabolic cost per unit distance and that which minimizes the net cost per unit distance (total minus resting cost). Minimizing the total cost per distance gives the maximum range speed and is a much better predictor of the speeds at which people and horses prefer to walk naturally. Minimizing the net cost per distance is equivalent to minimizing the total daily energy intake given an idealized modern lifestyle that requires one to walk a given distance every day--but it is not a good predictor of animals' walking speeds. Next, I critique the notion that there is no energy-optimal speed for running, making use of some recent experiments and a review of past literature. Finally, I consider the problem of predicting the speeds at which people walk on moving walkways--such as those found in some airports. I present two substantially different theories to make predictions. The first theory, minimizing total energy per distance, predicts that for a range of low walkway speeds, the optimal absolute speed of travel will be greater--but the speed relative to the walkway smaller--than the optimal walking speed on stationary ground. At higher walkway speeds, this theory predicts that the person will stand still. The second theory is based on the assumption that the human optimally reconciles the sensory conflict between the forward speed that the eye sees and the walking speed that the legs feel and tries to equate the best estimate of the forward speed to the naturally preferred speed. This sensory conflict theory also predicts that people would walk slower than usual relative to the walkway yet move faster than usual relative to the ground. These predictions agree qualitatively with available experimental observations, but there are quantitative differences. PMID:19566272

  12. Optimal speeds for walking and running, and walking on a moving walkway

    NASA Astrophysics Data System (ADS)

    Srinivasan, Manoj

    2009-06-01

    Many aspects of steady human locomotion are thought to be constrained by a tendency to minimize the expenditure of metabolic cost. This paper has three parts related to the theme of energetic optimality: (1) a brief review of energetic optimality in legged locomotion, (2) an examination of the notion of optimal locomotion speed, and (3) an analysis of walking on moving walkways, such as those found in some airports. First, I describe two possible connotations of the term "optimal locomotion speed:" that which minimizes the total metabolic cost per unit distance and that which minimizes the net cost per unit distance (total minus resting cost). Minimizing the total cost per distance gives the maximum range speed and is a much better predictor of the speeds at which people and horses prefer to walk naturally. Minimizing the net cost per distance is equivalent to minimizing the total daily energy intake given an idealized modern lifestyle that requires one to walk a given distance every day—but it is not a good predictor of animals' walking speeds. Next, I critique the notion that there is no energy-optimal speed for running, making use of some recent experiments and a review of past literature. Finally, I consider the problem of predicting the speeds at which people walk on moving walkways—such as those found in some airports. I present two substantially different theories to make predictions. The first theory, minimizing total energy per distance, predicts that for a range of low walkway speeds, the optimal absolute speed of travel will be greater—but the speed relative to the walkway smaller—than the optimal walking speed on stationary ground. At higher walkway speeds, this theory predicts that the person will stand still. The second theory is based on the assumption that the human optimally reconciles the sensory conflict between the forward speed that the eye sees and the walking speed that the legs feel and tries to equate the best estimate of the forward speed to the naturally preferred speed. This sensory conflict theory also predicts that people would walk slower than usual relative to the walkway yet move faster than usual relative to the ground. These predictions agree qualitatively with available experimental observations, but there are quantitative differences.

  13. Does parkland influence walking? The relationship between area of parkland and walking trips in Melbourne, Australia

    PubMed Central

    2012-01-01

    Background Using two different measures of park area, at three buffer distances, we sought to investigate the ways in which park area and proximity to parks, are related to the frequency of walking (for all purposes) in Australian adults. Little previous research has been conducted in this area, and results of existing research have been mixed. Methods Residents of 50 urban areas in metropolitan Melbourne, Australia completed a physical activity survey (n = 2305). Respondents reported how often they walked for ≥10 minutes in the previous month. Walking frequency was dichotomised to ‘less than weekly’ (less than 1/week) and ‘at least weekly’ (1/week or more). Using Geographic Information Systems, Euclidean buffers were created around each respondent’s home at three distances: 400metres (m), 800 m and 1200 m. Total area of parkland in each person’s buffer was calculated for the three buffers. Additionally, total area of ‘larger parks’, (park space ≥ park with Australian Rules Football oval (17,862 m2)), was calculated for each set of buffers. Area of park was categorised into tertiles for area of all parks, and area of larger parks (the lowest tertile was used as the reference category). Multilevel logistic regression, with individuals nested within areas, was used to estimate the effect of area of parkland on walking frequency. Results No statistically significant associations were found between walking frequency and park area (total and large parks) within 400 m of respondent’s homes. For total park area within 800 m, the odds of walking at least weekly were lower for those in the mid (OR 0.65, 95% CI 0.46-0.91) and highest (OR 0.65, 95% CI 0.44-0.95) tertile of park area compared to those living in areas with the least amount of park area. Similar results were observed for total park area in the 1200 m buffers. When only larger parks were investigated, again more frequent walking was less likely when respondents had access to a greater amount of park area. Conclusions In this study we found that more park area in residential environments reduced the odds of walking more frequently. Other area characteristics such as street connectivity and destinations may underlie these associations by negatively correlating with park area. PMID:22989176

  14. Effects of Nordic Walking Compared to Conventional Walking and Band-Based Resistance Exercise on Fitness in Older Adults

    PubMed Central

    Takeshima, Nobuo; Islam, Mohammod M.; Rogers, Michael E.; Rogers, Nicole L.; Sengoku, Naoko; Koizumi, Daisuke; Kitabayashi, Yukiko; Imai, Aiko; Naruse, Aiko

    2013-01-01

    The purpose of this study was to compare the effects of Nordic walking with conventional walking and band-based resistance exercise on functional fitness, static balance and dynamic balance in older adults. Volunteers (n = 65) were divided into four groups: Nordic walking (NW), conventional walking (CW), resistance (RES), and control. Each group performed activity 50-70 minday?1 (warm-up 10-15 min, main exercise 30-40, and cool down 10-15 min), 3 daysweek?1 (NW and CW) or 2 dayweek?1 (RES) for 12 wks. Upper-body strength improved (p < 0. 05) in the RES (22.3%) and the NW (11.6%) groups compared to the CW and control groups. Cardio- respiratory fitness improved more in the NW (10.9%) and CW (10.6%) groups compared to the RES and control groups. Upper- and lower-body flexibility also improved in all exercise groups compared to the control group. There were no improvements in balance measures in any group. While all modes of exercise improved various components of fitness, Nordic walking provided the best well-rounded benefits by improving upper-body strength, cardiovascular endurance, and flexibility. Therefore, Nordic walking is recommended as an effective and efficient mode of concurrent exercise to improve overall functional fitness in older adults. Key Points Nordic walking, conventional walking, and resistance training are beneficial for older adults. Nordic walking and conventional walking both improve cardio-respiratory fitness while resistance training does not. Nordic walking provides additional benefits in upper-body muscular strength compared to conventional walking. Nordic walking is an effective and efficient mode of exercise to improve overall fitness in older adults. PMID:24149147

  15. Determination of the oxygen cost of level walking.

    PubMed

    Linnarsson, D; Mattsson, E; Eklf, L; Broman, L; Broman, M; Brostrm, L A

    1989-02-01

    We have developed devices and methods for the determination of the oxygen cost of level walking. Oxygen uptake is determined with an argon dilution method. The validity of this technique is demonstrated. Walking speed is recorded and controlled by means of a speedometer cart. The reproducibility of a convenient, self-selected walking speed and of a predetermined speed was studied. Coefficients of variation were below two per cent. Corresponding values of the oxygen cost of walking at a predetermined speed were three per cent or less up to an interval between tests of six months. We conclude that the proposed methods are suited for longitudinal studies of the oxygen cost of level walking, for example in patients with walking disorders. PMID:2706911

  16. Bicycling and Walking are Associated with Different Cortical Oscillatory Dynamics.

    PubMed

    Storzer, Lena; Butz, Markus; Hirschmann, Jan; Abbasi, Omid; Gratkowski, Maciej; Saupe, Dietmar; Schnitzler, Alfons; Dalal, Sarang S

    2016-01-01

    Although bicycling and walking involve similar complex coordinated movements, surprisingly Parkinson's patients with freezing of gait typically remain able to bicycle despite severe difficulties in walking. This observation suggests functional differences in the motor networks subserving bicycling and walking. However, a direct comparison of brain activity related to bicycling and walking has never been performed, neither in healthy participants nor in patients. Such a comparison could potentially help elucidating the cortical involvement in motor control and the mechanisms through which bicycling ability may be preserved in patients with freezing of gait. The aim of this study was to contrast the cortical oscillatory dynamics involved in bicycling and walking in healthy participants. To this end, EEG and EMG data of 14 healthy participants were analyzed, who cycled on a stationary bicycle at a slow cadence of 40 revolutions per minute (rpm) and walked at 40 strides per minute (spm), respectively. Relative to walking, bicycling was associated with a stronger power decrease in the high beta band (23-35 Hz) during movement initiation and execution, followed by a stronger beta power increase after movement termination. Walking, on the other hand, was characterized by a stronger and persisting alpha power (8-12 Hz) decrease. Both bicycling and walking exhibited movement cycle-dependent power modulation in the 24-40 Hz range that was correlated with EMG activity. This modulation was significantly stronger in walking. The present findings reveal differential cortical oscillatory dynamics in motor control for two types of complex coordinated motor behavior, i.e., bicycling and walking. Bicycling was associated with a stronger sustained cortical activation as indicated by the stronger high beta power decrease during movement execution and less cortical motor control within the movement cycle. We speculate this to be due to the more continuous nature of bicycling demanding less phase-dependent sensory processing and motor planning, as opposed to walking. PMID:26924977

  17. Mall Walking Program Environments, Features, and Participants: A Scoping Review

    PubMed Central

    Belza, Basia; Allen, Peg; Brolliar, Sarah; Brown, David R.; Cormier, Marc L.; Janicek, Sarah; Jones, Dina L.; King, Diane K.; Marquez, David X.; Rosenberg, Dori E.

    2015-01-01

    Introduction Walking is a preferred and recommended physical activity for middle-aged and older adults, but many barriers exist, including concerns about safety (ie, personal security), falling, and inclement weather. Mall walking programs may overcome these barriers. The purpose of this study was to summarize the evidence on the health-related value of mall walking and mall walking programs. Methods We conducted a scoping review of the literature to determine the features, environments, and benefits of mall walking programs using the RE-AIM framework (reach, effectiveness, adoption, implementation, and maintenance). The inclusion criteria were articles that involved adults aged 45 years or older who walked in indoor or outdoor shopping malls. Exclusion criteria were articles that used malls as laboratory settings or focused on the mechanics of walking. We included published research studies, dissertations, theses, conference abstracts, syntheses, nonresearch articles, theoretical papers, editorials, reports, policy briefs, standards and guidelines, and nonresearch conference abstracts and proposals. Websites and articles written in a language other than English were excluded. Results We located 254 articles on mall walking; 32 articles met our inclusion criteria. We found that malls provided safe, accessible, and affordable exercise environments for middle-aged and older adults. Programmatic features such as program leaders, blood pressure checks, and warm-up exercises facilitated participation. Individual benefits of mall walking programs included improvements in physical, social, and emotional well-being. Limited transportation to the mall was a barrier to participation. Conclusion We found the potential for mall walking programs to be implemented in various communities as a health promotion measure. However, the research on mall walking programs is limited and has weak study designs. More rigorous research is needed to define best practices for mall walking programs’ reach, effectiveness, adoption, implementation, and maintenance. PMID:26270743

  18. Bicycling and Walking are Associated with Different Cortical Oscillatory Dynamics

    PubMed Central

    Storzer, Lena; Butz, Markus; Hirschmann, Jan; Abbasi, Omid; Gratkowski, Maciej; Saupe, Dietmar; Schnitzler, Alfons; Dalal, Sarang S.

    2016-01-01

    Although bicycling and walking involve similar complex coordinated movements, surprisingly Parkinson’s patients with freezing of gait typically remain able to bicycle despite severe difficulties in walking. This observation suggests functional differences in the motor networks subserving bicycling and walking. However, a direct comparison of brain activity related to bicycling and walking has never been performed, neither in healthy participants nor in patients. Such a comparison could potentially help elucidating the cortical involvement in motor control and the mechanisms through which bicycling ability may be preserved in patients with freezing of gait. The aim of this study was to contrast the cortical oscillatory dynamics involved in bicycling and walking in healthy participants. To this end, EEG and EMG data of 14 healthy participants were analyzed, who cycled on a stationary bicycle at a slow cadence of 40 revolutions per minute (rpm) and walked at 40 strides per minute (spm), respectively. Relative to walking, bicycling was associated with a stronger power decrease in the high beta band (23–35 Hz) during movement initiation and execution, followed by a stronger beta power increase after movement termination. Walking, on the other hand, was characterized by a stronger and persisting alpha power (8–12 Hz) decrease. Both bicycling and walking exhibited movement cycle-dependent power modulation in the 24–40 Hz range that was correlated with EMG activity. This modulation was significantly stronger in walking. The present findings reveal differential cortical oscillatory dynamics in motor control for two types of complex coordinated motor behavior, i.e., bicycling and walking. Bicycling was associated with a stronger sustained cortical activation as indicated by the stronger high beta power decrease during movement execution and less cortical motor control within the movement cycle. We speculate this to be due to the more continuous nature of bicycling demanding less phase-dependent sensory processing and motor planning, as opposed to walking. PMID:26924977

  19. Tempo and walking speed with music in the urban context

    PubMed Central

    Franěk, Marek; van Noorden, Leon; Režný, Lukáš

    2014-01-01

    The study explored the effect of music on the temporal aspects of walking behavior in a real outdoor urban setting. First, spontaneous synchronization between the beat of the music and step tempo was explored. The effect of motivational and non-motivational music (Karageorghis et al., 1999) on the walking speed was also studied. Finally, we investigated whether music can mask the effects of visual aspects of the walking route environment, which involve fluctuation of walking speed as a response to particular environmental settings. In two experiments, we asked participants to walk around an urban route that was 1.8 km in length through various environments in the downtown area of Hradec Králové. In Experiment 1, the participants listened to a musical track consisting of world pop music with a clear beat. In Experiment 2, participants were walking either with motivational music, which had a fast tempo and a strong rhythm, or with non-motivational music, which was slower, nice music, but with no strong implication to movement. Musical beat, as well as the sonic character of the music listened to while walking, influenced walking speed but did not lead to precise synchronization. It was found that many subjects did not spontaneously synchronize with the beat of the music at all, and some subjects synchronized only part of the time. The fast, energetic music increases the speed of the walking tempo, while slower, relaxing music makes the walking tempo slower. Further, it was found that listening to music with headphones while walking can mask the influence of the surrounding environment to some extent. Both motivational music and non-motivational music had a larger effect than the world pop music from Experiment 1. Individual differences in responses to the music listened to while walking that were linked to extraversion and neuroticism were also observed. The findings described here could be useful in rhythmic stimulation for enhancing or recovering the features of movement performance. PMID:25520682

  20. Self-avoiding walks subject to a force

    NASA Astrophysics Data System (ADS)

    Janse van Rensburg, E. J.; Whittington, S. G.

    2016-03-01

    We prove some theorems about self-avoiding walks attached to an impenetrable surface (i.e. positive walks) and subject to a force. Specifically we show the force dependence of the free energy is identical when the force is applied at the last vertex or at the top (confining) plane. We discuss the relevance of this result to numerical results and to a recent result about convergence rates when the walk is being pushed towards the surface.

  1. Tempo and walking speed with music in the urban context.

    PubMed

    Fran?k, Marek; van Noorden, Leon; Ren, Luk

    2014-01-01

    The study explored the effect of music on the temporal aspects of walking behavior in a real outdoor urban setting. First, spontaneous synchronization between the beat of the music and step tempo was explored. The effect of motivational and non-motivational music (Karageorghis et al., 1999) on the walking speed was also studied. Finally, we investigated whether music can mask the effects of visual aspects of the walking route environment, which involve fluctuation of walking speed as a response to particular environmental settings. In two experiments, we asked participants to walk around an urban route that was 1.8 km in length through various environments in the downtown area of Hradec Krlov. In Experiment 1, the participants listened to a musical track consisting of world pop music with a clear beat. In Experiment 2, participants were walking either with motivational music, which had a fast tempo and a strong rhythm, or with non-motivational music, which was slower, nice music, but with no strong implication to movement. Musical beat, as well as the sonic character of the music listened to while walking, influenced walking speed but did not lead to precise synchronization. It was found that many subjects did not spontaneously synchronize with the beat of the music at all, and some subjects synchronized only part of the time. The fast, energetic music increases the speed of the walking tempo, while slower, relaxing music makes the walking tempo slower. Further, it was found that listening to music with headphones while walking can mask the influence of the surrounding environment to some extent. Both motivational music and non-motivational music had a larger effect than the world pop music from Experiment 1. Individual differences in responses to the music listened to while walking that were linked to extraversion and neuroticism were also observed. The findings described here could be useful in rhythmic stimulation for enhancing or recovering the features of movement performance. PMID:25520682

  2. Factors influencing dynamic prioritization during dual-task walking in healthy young adults.

    PubMed

    Kelly, Valerie E; Eusterbrock, Alexis J; Shumway-Cook, Anne

    2013-01-01

    Appropriate prioritization during dual-task walking is necessary to achieve task goals and maintain walking stability. We examined the effects of increased walking task difficulty on dual-task walking prioritization in healthy young adults. Walking under simple usual-base conditions was similar between equal-focus and cognitive-focus instructions, but these differed from walking-focus instructions, consistent with cognitive task prioritization. In contrast, narrow-base walking was similar between equal-focus and walking-focus instructions, but these differed from cognitive-focus instructions. This shift in prioritization with increasing walking task difficulty suggests that prioritization is dynamic and flexible. PMID:22940543

  3. Delayed Random Walk with a Repulsive Origin

    NASA Astrophysics Data System (ADS)

    Hosaka, Tadaaki; Ohira, Toru; Milton, John G.; Cabrera, Juan Luis

    2004-03-01

    An important question concerns how unstable equilibria can be stabilized using time-delayed corrections in the presence of noise. Recently the interplay between noise and delay has been emphasized as an essential component of the neural control of stick balancing at the fingertip [1]: The beneficial effects of noise were related to on-off intermittency; However, the effects of the delay on control were not fully investigated. Here we investigate the effects of delayed corrective movements on the stabilization of an unstable equilibrium using a simpler model, namely a delayed random walk[2]. A delayed random walk for an unstable equilibrium is one in which the transition probability depends on the position of the walker at time tau in the past and transitions in the direction away from the unstable point are more probable. Numerical simulations demonstrate t hat both the first passage time to cross a specified threshold and the return time distribution to the origin increase as the delay increases. Thus the diffusion of the walker away from the unstable fixed point is slower the longer the delay. This is in contrast to the case with the stable fixed point where delay makes diffusion faster. These observations may have implications for the design of artificial and natural feedback control systems in general. [1] J. L. Cabrera and J. G. Milton, "On-Off Intermittency in a Human Balancing", Phys.Rev.Lett. Vol. 89, p.. 158702, 2002. [2] T. Ohira and J. G. Milton, "Delayed Random Walks", Phys.Rev.E Vol. 52, pp. 3277-3280, 1995.

  4. Mechanism And Control Of The Quadruped Walking Robot

    NASA Astrophysics Data System (ADS)

    Adachi, Hironori; Nakano, Eiji; Koyachi, Noriho

    1987-10-01

    This paper provides a description of the quadruped walking robot "TURTLE-1". A new link mechanism named ASTBALLEM is used for the legs of this robot. With this mechanism highly rigid and easily controllable legs are constructed. Each leg has two degrees of freedom and is driven by two DC servo motors. The motion of the legs is controlled by a micro computer and various gaits are generated. Static stability is maintained as the robot walks. Moreover, its walk is quasi-dynamic; that is, it has a manner of walking that has a two legged supporting period.

  5. Random recursive trees and the elephant random walk

    NASA Astrophysics Data System (ADS)

    Kürsten, Rüdiger

    2016-03-01

    One class of random walks with infinite memory, so-called elephant random walks, are simple models describing anomalous diffusion. We present a surprising connection between these models and bond percolation on random recursive trees. We use a coupling between the two models to translate results from elephant random walks to the percolation process. We calculate, besides other quantities, exact expressions for the first and the second moment of the root cluster size and of the number of nodes in child clusters of the first generation. We further introduce another model, the skew elephant random walk, and calculate the first and second moment of this process.

  6. Qubit state transfer via discrete-time quantum walks

    NASA Astrophysics Data System (ADS)

    Yal?nkaya, ?skender; Gedik, Zafer

    2015-06-01

    We propose a scheme for perfect transfer of an unknown qubit state via the discrete-time quantum walk on a line or a circle. For this purpose, we introduce an additional coin operator which is applied at the end of the walk. This operator does not depend on the state to be transferred. We show that perfect state transfer over an arbitrary distance can be achieved only if the walk is driven by an identity or a flip coin operator. Other biased coin operators and the Hadamard coin allow perfect state transfer over finite distances only. Furthermore, we show that quantum walks ending with a perfect state transfer are periodic.

  7. Interrupting Sitting Time with Regular Walks Attenuates Postprandial Triglycerides.

    PubMed

    Miyashita, M; Edamoto, K; Kidokoro, T; Yanaoka, T; Kashiwabara, K; Takahashi, M; Burns, S

    2016-02-01

    We compared the effects of prolonged sitting with the effects of sitting interrupted by regular walking and the effects of prolonged sitting after continuous walking on postprandial triglyceride in postmenopausal women. 15 participants completed 3 trials in random order: 1) prolonged sitting, 2) regular walking, and 3) prolonged sitting preceded by continuous walking. During the sitting trial, participants rested for 8?h. For the walking trials, participants walked briskly in either twenty 90-sec bouts over 8?h or one 30-min bout in the morning (09:00-09:30). Except for walking, both exercise trials mimicked the sitting trial. In each trial, participants consumed a breakfast (08:00) and lunch (11:00). Blood samples were collected in the fasted state and at 2, 4, 6 and 8?h after breakfast. The serum triglyceride incremental area under the curve was 15 and 14% lower after regular walking compared with prolonged sitting and prolonged sitting after continuous walking (4.732.50 vs. 5.522.95 vs. 5.502.59?mmol/L?8?h respectively, main effect of trial: P=0.023). Regularly interrupting sitting time with brief bouts of physical activity can reduce postprandial triglyceride in postmenopausal women. PMID:26509374

  8. Metal-insulator transition in 2D quantum walks

    NASA Astrophysics Data System (ADS)

    Edge, Jonathan; Asboth, Janos

    2015-03-01

    We investigate the localisation properties due to disorder of several different two-dimensional quantum walks. We find that, contrary to claims in the literature, the Hadamard quantum walk does not localise. In a different quantum walk system we find a way to induce localisation. By tuning the parameters of the system we further manage to drive the quantum walk through a metal-insulator transition and show that the transition is related to the plateau transition of the integer quantum Hall effect. Hungarian National Office for Research.

  9. Quantum-walk-based search and centrality

    SciTech Connect

    Berry, Scott D.; Wang, Jingbo B.

    2010-10-15

    We study the discrete-time quantum-walk-based search for a marked vertex on a graph. By considering various structures in which not all vertices are equivalent, we investigate the relationship between the successful search probability and the position of the marked vertex, in particular, its centrality. We find that the maximum value of the search probability does not necessarily increase as the marked vertex becomes more central, and we investigate an interesting relationship between the frequency of the successful search probability and the centrality of the marked vertex.

  10. Vertical engine for walk behind lawn mower

    SciTech Connect

    Isaka, Y.; Oguri, K.

    1988-03-01

    This patent describes a lawn mower or other similar walk behind type of implement that is designed to be operated in a normally erect position and which is tilted to the side for servicing. An engine is provided for the lawn mower having an output shaft rotatable about a vertically extending axis. The engine includes a lubricating system incorporating a crankcase in which the engine output shaft rotates and a crankcase ventilating system. The crankcase ventilating system is designed so as to prevent lubricant from flowing into the induction system when the engine is tilted on its side.

  11. Novel Image Encryption based on Quantum Walks

    PubMed Central

    Yang, Yu-Guang; Pan, Qing-Xiang; Sun, Si-Jia; Xu, Peng

    2015-01-01

    Quantum computation has achieved a tremendous success during the last decades. In this paper, we investigate the potential application of a famous quantum computation model, i.e., quantum walks (QW) in image encryption. It is found that QW can serve as an excellent key generator thanks to its inherent nonlinear chaotic dynamic behavior. Furthermore, we construct a novel QW-based image encryption algorithm. Simulations and performance comparisons show that the proposal is secure enough for image encryption and outperforms prior works. It also opens the door towards introducing quantum computation into image encryption and promotes the convergence between quantum computation and image processing. PMID:25586889

  12. Novel image encryption based on quantum walks.

    PubMed

    Yang, Yu-Guang; Pan, Qing-Xiang; Sun, Si-Jia; Xu, Peng

    2015-01-01

    Quantum computation has achieved a tremendous success during the last decades. In this paper, we investigate the potential application of a famous quantum computation model, i.e., quantum walks (QW) in image encryption. It is found that QW can serve as an excellent key generator thanks to its inherent nonlinear chaotic dynamic behavior. Furthermore, we construct a novel QW-based image encryption algorithm. Simulations and performance comparisons show that the proposal is secure enough for image encryption and outperforms prior works. It also opens the door towards introducing quantum computation into image encryption and promotes the convergence between quantum computation and image processing. PMID:25586889

  13. Scalable networks for discrete quantum random walks

    SciTech Connect

    Fujiwara, S.; Osaki, H.; Buluta, I.M.; Hasegawa, S.

    2005-09-15

    Recently, quantum random walks (QRWs) have been thoroughly studied in order to develop new quantum algorithms. In this paper we propose scalable quantum networks for discrete QRWs on circles, lines, and also in higher dimensions. In our method the information about the position of the walker is stored in a quantum register and the network consists of only one-qubit rotation and (controlled){sup n}-NOT gates, therefore it is purely computational and independent of the physical implementation. As an example, we describe the experimental realization in an ion-trap system.

  14. Walking during body-weight-supported treadmill training and acute responses to varying walking speed and body-weight support in ambulatory patients post-stroke.

    PubMed

    Aaslund, Mona Kristin; Helbostad, Jorunn Lgdheim; Moe-Nilssen, Rolf

    2013-05-01

    Rehabilitating walking in ambulatory patients post-stroke, with training that is safe, task-specific, intensive, and of sufficient duration, can be challenging. Some challenges can be met by using body-weight-supported treadmill training (BWSTT). However, it is not known to what degree walking characteristics are similar during BWSTT and overground walking. In addition, important questions regarding the training protocol of BWSTT remain unanswered, such as how proportion of body-weight support (BWS) and walking speed affect walking characteristics during training. The objective was therefore to investigate if and how kinematic walking characteristics are different between overground walking and treadmill walking with BWS in ambulatory patients post-stroke, and the acute response of altering walking speed and percent BWS during treadmill walking with BWS. A cross-sectional repeated-measures design was used. Ambulating patients post-stroke walked in slow, preferred, and fast walking speed overground and at comparable speeds on the treadmill with 20% and 40% BWS. Kinematic walking characteristics were obtained using a kinematic sensor attached over the lower back. Forty-four patients completed the protocol. Kinematic walking characteristics were similar during treadmill walking with BWS, compared to walking overground. During treadmill walking, choice of walking speed had greater impact on kinematic walking characteristics than proportion of BWS. Faster walking speeds tended to affect the kinematic walking characteristics positively. This implies that in order to train safely and with sufficient intensity and duration, therapists may choose to include BWSTT in walking rehabilitation also for ambulatory patients post-stroke without aggravating gait pattern during training. PMID:23039016

  15. Learning to Walk, Walking to Learn: Reconsidering the Walkthrough as an Improvement Strategy

    ERIC Educational Resources Information Center

    Lemons, Richard W.; Helsing, Deborah

    2009-01-01

    School leaders desperate for strategies that will improve student learning have often opted to embrace strategies that they have observed being used successfully in other districts. Sometimes, this works; sometimes, it does not. This article presents two vignettes about districts that made similar decisions to implement learning walks. The

  16. Walking the walk while thinking about the talk: embodied interpretation of metaphorical narratives.

    PubMed

    Gibbs, Raymond W

    2013-08-01

    Two sets of experiments examined people's embodied understanding of metaphorical narratives. Participants heard one of two stories about a romantic relationship; either one that was successful or one that was not, that initially described it in metaphorical terms as "Your relationship was moving along in a good direction" or nonmetaphorical terms as "Your relationship was very important to you." Participants were then blindfolded and attempted to accurately walk, or imagine walking, to a marker 40 feet away while they thought about the story they just heard. People who heard about the successful metaphorical story walked longer and further than those presented with the unsuccessful relationship story. But these walking and imagining differences disappeared when the critical metaphorical statement "moving along in a good direction" was replaced by a nonmetaphorical expression. These findings, and those from another set of experiments, suggest that people's understanding of metaphorical narratives is partly based on their embodied simulations of the metaphorical actions referred to in these stories. PMID:22585389

  17. Gait Pattern Alterations during Walking, Texting and Walking and Texting during Cognitively Distractive Tasks while Negotiating Common Pedestrian Obstacles

    PubMed Central

    Licence, Sammy; Smith, Robynne; McGuigan, Miranda P.; Earnest, Conrad P.

    2015-01-01

    Objectives Mobile phone texting is a common daily occurrence with a paucity of research examining corresponding gait characteristics. To date, most studies have participants walk in a straight line vs. overcoming barriers and obstacles that occur during regular walking. The aim of our study is to examine the effect of mobile phone texting during periods of cognitive distraction while walking and negotiating barriers synonymous with pedestrian traffic. Methods Thirty participants (18-50y) completed three randomized, counter-balanced walking tasks over a course during: (1) normal walking (control), (2) texting and walking, and (3) texting and walking whilst being cognitively distraction via a standard mathematical test performed while negotiating the obstacle course. We analyzed gait characteristics during course negotiation using a 3-dimensional motion analysis system and a general linear model and Dunnet-Hsu post-hoc procedure the normal walking condition to assess gait characteristic differences. Primary outcomes included the overall time to complete the course time and barrier contact. Secondary outcomes included obstacle clearance height, step frequency, step time, double support phase and lateral deviation. Results Participants took significantly longer (mean ± SD) to complete the course while texting (24.96±4.20 sec) and during cognitive distraction COG (24.09±3.36 sec) vs. normal walking (19.32±2.28 sec; all, P<0.001). No significant differences were noted for barrier contacts (P = 0.28). Step frequency, step time, double support phase and lateral deviation all increased in duration during the texting and cognitive distraction trial. Texting and being cognitively distracted also increased obstacle clearance versus the walking condition (all, P<0.02). Conclusions Texting while walking and/or being cognitively distracted significantly affect gait characteristics concordant to mobile phone usage resulting in a more cautious gate pattern. Future research should also examine a similar study in older participants who may be at a greater risk of tripping with such walking deviations. PMID:26222430

  18. Behavioral and Neural Correlates of Imagined Walking and Walking-While-Talking in the Elderly

    PubMed Central

    Blumen, Helena M.; Holtzer, Roee; Brown, Lucy L.; Gazes, Yunglin; Verghese, Joe

    2014-01-01

    Cognition is important for locomotion and gait decline increases the risk for morbidity, mortality, cognitive decline, and dementia. Yet, the neural correlates of gait are not well established, because most neuroimaging methods cannot image the brain during locomotion. Imagined gait protocols overcome this limitation. This study examined the behavioral and neural correlates of a new imagined gait protocol that involved imagined walking (iW), imagined talking (iT), and imagined walking-while-talking (iWWT). In Experiment 1, 82 cognitively-healthy older adults (M = 80.45) walked (W), iW, walked while talking (WWT) and iWWT. Real and imagined walking task times were strongly correlated, particularly real and imagined dual-task times (WWT and iWWT). In Experiment 2, 33 cognitively-healthy older adults (M = 73.03) iW, iT, and iWWT during functional Magnetic Resonance Imaging. A multivariate Ordinal Trend (OrT) Covariance analysis identified a pattern of brain regions that: 1) varied as a function of imagery task difficulty (iW, iT and iWWT), 2) involved cerebellar, precuneus, supplementary motor and other prefrontal regions, and 3) were associated with kinesthetic imagery ratings and behavioral performance during actual WWT. This is the first study to compare the behavioral and neural correlates of imagined gait in single and dual-task situations, an issue that is particularly relevant to elderly populations. These initial findings encourage further research and development of this imagined gait protocol as a tool for improving gait and cognition among the elderly. PMID:24522972

  19. Environmental Correlates of Recreational Walking in the Neighborhood.

    PubMed

    Nehme, Eileen K; Oluyomi, Abiodun O; Calise, Tamara Vehige; Kohl, Harold W

    2016-01-01

    Purpose . To assess environmental correlates of neighborhood recreational walking. Design . The study used a cross-sectional survey. Setting . The study was conducted in the local community. Subjects . Participants were adults who recently relocated and walk for recreation in their current neighborhood. Measures . The outcome measure was participant-reported neighborhood recreational walking in participants' prior neighborhood. Exposure measures were (1) participant-reported social and environmental characteristics of the prior neighborhood and (2) geographic information system-derived environmental characteristics assessed within a buffer around participant's prior address. Analysis . Participants reporting current neighborhood recreational walking (n = 231) were characterized by whether they walked for recreation in their prior neighborhood. Associations between neighborhood characteristics and neighborhood recreational walking were assessed using logistic regression. Results . Neighborhood recreational walking was associated with perceptions of the presence of recreational facilities (odds ratio [OR] = 2.49, 95% confidence interval [CI] = 1.29-4.84), interesting things to see (OR = 2.82, 95% CI = 1.46-5.45), and others being active (OR = 3.56, 95% CI = 1.80-7.05), and was inversely associated with concerns about crime (OR = .40, 95% CI = .20-.77) and traffic (OR = .43, 95% CI = .22-.87). This behavior was associated with objectively measured presence of walking trails (OR = 3.58, 95% CI = 1.07-4.46), percentage of street length with speed limits ≤25 mph (OR = 1.31 for 10% increase, 95% CI = 1.08-1.61), and percentage of tree canopy coverage (OR = 1.55 for 10% increase, 95% CI = 1.12-2.14). Conclusion . Recreational walking may be influenced by environmental factors that support a safe, enjoyable, and social experience, attributes that are not necessarily prioritized in transportation walking. Outcome and exposure specificity are important when studying recreational walking. PMID:25615703

  20. Inferring Lvy walks from curved trajectories: A rescaling method

    NASA Astrophysics Data System (ADS)

    Tromer, R. M.; Barbosa, M. B.; Bartumeus, F.; Catalan, J.; da Luz, M. G. E.; Raposo, E. P.; Viswanathan, G. M.

    2015-08-01

    An important problem in the study of anomalous diffusion and transport concerns the proper analysis of trajectory data. The analysis and inference of Lvy walk patterns from empirical or simulated trajectories of particles in two and three-dimensional spaces (2D and 3D) is much more difficult than in 1D because path curvature is nonexistent in 1D but quite common in higher dimensions. Recently, a new method for detecting Lvy walks, which considers 1D projections of 2D or 3D trajectory data, has been proposed by Humphries et al. The key new idea is to exploit the fact that the 1D projection of a high-dimensional Lvy walk is itself a Lvy walk. Here, we ask whether or not this projection method is powerful enough to cleanly distinguish 2D Lvy walk with added curvature from a simple Markovian correlated random walk. We study the especially challenging case in which both 2D walks have exactly identical probability density functions (pdf) of step sizes as well as of turning angles between successive steps. Our approach extends the original projection method by introducing a rescaling of the projected data. Upon projection and coarse-graining, the renormalized pdf for the travel distances between successive turnings is seen to possess a fat tail when there is an underlying Lvy process. We exploit this effect to infer a Lvy walk process in the original high-dimensional curved trajectory. In contrast, no fat tail appears when a (Markovian) correlated random walk is analyzed in this way. We show that this procedure works extremely well in clearly identifying a Lvy walk even when there is noise from curvature. The present protocol may be useful in realistic contexts involving ongoing debates on the presence (or not) of Lvy walks related to animal movement on land (2D) and in air and oceans (3D).

  1. Human energy expenditure when walking on a moving platform.

    PubMed

    Heus, R; Wertheim, A H; Havenith, G

    1998-03-01

    The assumption that working on board ship is more strenuous than comparable work ashore was investigated in this study. Various physiological parameters (VO2, VCO2, VE and HR) have been measured to determine the energy expenditure of subjects walking slowly on a moving platform (ship motion simulator). Twelve subjects (eight men and four women) walked either freely on the floor or on a treadmill at a speed of 1 m x s(-1). Platform motion was either in a heave, pitch or roll mode. These three conditions were compared with a control condition in which the platform remained stationary. The results showed that during pitch and roll movements of the platform, the energy expenditure for the same walking task was about 30% higher than under the stationary control condition (3.6 J x kg[-1] x m[-1] vs 2.5 J x kg[-1] x m[-1], P < 0.05) for both walking on a treadmill and free walking. The heart rate data supported the higher energy expenditure results with an elevation of the heart rate (112 beats x min[-1] vs 103 beats x min[-1], P < 0.05). The heave condition did not differ significantly from the stationary control condition. Pitch and roll were not significantly different from each other. During all experimental conditions free walking resulted in a higher energy cost of walking than treadmill walking (3.5 J x kg[-1] x m[-1] vs 2.7 J x kg[-1] x m[-1], P < 0.05) at the same average speed. The results of this experiment were interpreted as indicating that the muscular effort, needed for maintaining balance when walking on a pitching or rolling platform, resulted in a significantly higher work load than similar walking on a stable or a heaving floor, independent of the mode of walking. These results explain in part the increased fatigue observed when a task is performed on a moving platform. PMID:9562369

  2. Random walk with priorities in communicationlike networks

    NASA Astrophysics Data System (ADS)

    Bastas, Nikolaos; Maragakis, Michalis; Argyrakis, Panos; ben-Avraham, Daniel; Havlin, Shlomo; Carmi, Shai

    2013-08-01

    We study a model for a random walk of two classes of particles (A and B). Where both species are present in the same site, the motion of A's takes precedence over that of B's. The model was originally proposed and analyzed in Maragakis [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.77.020103 77, 020103(R) (2008)]; here we provide additional results. We solve analytically the diffusion coefficients of the two species in lattices for a number of protocols. In networks, we find that the probability of a B particle to be free decreases exponentially with the node degree. In scale-free networks, this leads to localization of the B's at the hubs and arrest of their motion. To remedy this, we investigate several strategies to avoid trapping of the B's, including moving an A instead of the hindered B, allowing a trapped B to hop with a small probability, biased walk toward non-hub nodes, and limiting the capacity of nodes. We obtain analytic results for lattices and networks, and we discuss the advantages and shortcomings of the possible strategies.

  3. Too far to walk or bike?

    PubMed

    Larouche, Richard; Barnes, Joel; Tremblay, Mark S

    2013-01-01

    Only 25-35% of Canadian children and youth regularly engage in active transportation (AT; e.g., non-motorized travel modes such as walking and cycling) to/from school. Previous research shows that distance between home and school is the strongest barrier to AT. Based on social ecological theory, we describe several strategies to overcome this barrier. At the individual level, children and youth could engage in AT to/from destinations such as parks, shops, friends' and family members' residence, and sport fields which may be located closer than their school. Parents who drive their kids to/from school could drop them within a "walkable" distance so that they can walk for the remainder of the trip. Partnerships could be developed between schools and other nearby institutions that would allow cars and buses to use their parking lot temporarily so that children could do a portion of the school trip on foot. Developing a well-connected network of sidewalks along low traffic streets can also facilitate AT. At the policy level, decisions regarding school location have a direct influence on distance. Finally, social marketing campaigns could raise awareness about strategies to incorporate AT into one's lifestyle, and encourage parents to reconsider what constitutes a "walkable" distance. PMID:24495826

  4. Improving the accuracy of walking piezo motors.

    PubMed

    den Heijer, M; Fokkema, V; Saedi, A; Schakel, P; Rost, M J

    2014-05-01

    Many application areas require ultraprecise, stiff, and compact actuator systems with a high positioning resolution in combination with a large range as well as a high holding and pushing force. One promising solution to meet these conflicting requirements is a walking piezo motor that works with two pairs of piezo elements such that the movement is taken over by one pair, once the other pair reaches its maximum travel distance. A resolution in the pm-range can be achieved, if operating the motor within the travel range of one piezo pair. However, applying the typical walking drive signals, we measure jumps in the displacement up to 2.4 ?m, when the movement is given over from one piezo pair to the other. We analyze the reason for these large jumps and propose improved drive signals. The implementation of our new drive signals reduces the jumps to less than 42 nm and makes the motor ideally suitable to operate as a coarse approach motor in an ultra-high vacuum scanning tunneling microscope. The rigidity of the motor is reflected in its high pushing force of 6.4 N. PMID:24880408

  5. Improving the accuracy of walking piezo motors

    NASA Astrophysics Data System (ADS)

    den Heijer, M.; Fokkema, V.; Saedi, A.; Schakel, P.; Rost, M. J.

    2014-05-01

    Many application areas require ultraprecise, stiff, and compact actuator systems with a high positioning resolution in combination with a large range as well as a high holding and pushing force. One promising solution to meet these conflicting requirements is a walking piezo motor that works with two pairs of piezo elements such that the movement is taken over by one pair, once the other pair reaches its maximum travel distance. A resolution in the pm-range can be achieved, if operating the motor within the travel range of one piezo pair. However, applying the typical walking drive signals, we measure jumps in the displacement up to 2.4 ?m, when the movement is given over from one piezo pair to the other. We analyze the reason for these large jumps and propose improved drive signals. The implementation of our new drive signals reduces the jumps to less than 42 nm and makes the motor ideally suitable to operate as a coarse approach motor in an ultra-high vacuum scanning tunneling microscope. The rigidity of the motor is reflected in its high pushing force of 6.4 N.

  6. The 1991-1992 walking robot design

    NASA Technical Reports Server (NTRS)

    Azarm, Shapour; Dayawansa, Wijesurija; Tsai, Lung-Wen; Peritt, Jon

    1992-01-01

    The University of Maryland Walking Machine team designed and constructed a robot. This robot was completed in two phases with supervision and suggestions from three professors and one graduate teaching assistant. Bob was designed during the Fall Semester 1991, then machined, assembled, and debugged in the Spring Semester 1992. The project required a total of 4,300 student hours and cost under $8,000. Mechanically, Bob was an exercise in optimization. The robot was designed to test several diverse aspects of robotic potential, including speed, agility, and stability, with simplicity and reliability holding equal importance. For speed and smooth walking motion, the footpath contained a long horizontal component; a vertical aspect was included to allow clearance of obstacles. These challenges were met with a leg design that utilized a unique multi-link mechanism which traveled a modified tear-drop footpath. The electrical requirements included motor, encoder, and voice control circuitry selection, manual controller manufacture, and creation of sensors for guidance. Further, there was also a need for selection of the computer, completion of a preliminary program, and testing of the robot.

  7. Spectrum of self-avoiding walk exponents

    NASA Astrophysics Data System (ADS)

    Douglas, Jack; Guttman, Charles M.; Mah, Alex; Ishinabe, Takao

    1997-01-01

    A short range interaction is incorporated into the self-avoiding walk (SAW) model of polymer chains by partitioning SAW's into equivalence classes of chain configurations having m nearest-neighbor contacts, and performing an energetically weighted averaging over these restricted SAW configurations. Surprisingly, there have been limited studies of the geometrical properties of 'contact-constrained' SAW configurations, which contrasts with the well studied unrestricted SAW"s. Accordingly, we generate Monte Carlo data for the total number of SAW configurations Cn,m having a fixed number of contacts m for chains of length n on square and cubic lattices. Applications of the standard ratio method to the Cn,m data shows a unique connectivity constant ? (NAW), corresponding to neighbor-avoiding walks (m=0), and a 'spectrum' of ? exponents which depend on the contact number m. The asymptotic scaling of the number of contact-constrained SAW's is found to be similar to the number of lattice animals and random plaquette surfaces having a fixed cyclomatic index c and genus g, respectively. The existence of this common structure is promising for the development of an analytic theory of interacting polymers and surfaces.

  8. 10 CFR 431.304 - Uniform test method for the measurement of energy consumption of walk-in coolers and walk-in...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Uniform test method for the measurement of energy consumption of walk-in coolers and walk-in freezers. 431.304 Section 431.304 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers Test Procedures...

  9. 10 CFR 431.304 - Uniform test method for the measurement of energy consumption of walk-in coolers and walk-in...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Uniform test method for the measurement of energy consumption of walk-in coolers and walk-in freezers. 431.304 Section 431.304 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers Test Procedures...

  10. Technology-Based Programs to Promote Walking Fluency or Improve Foot-Ground Contact during Walking: Two Case Studies of Adults with Multiple Disabilities

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; La Martire, Maria L.; Oliva, Doretta; Groeneweg, Jop

    2012-01-01

    These two case studies assessed technology-based programs for promoting walking fluency and improving foot-ground contact during walking with a man and a woman with multiple disabilities, respectively. The man showed breaks during walking and the woman presented with toe walking. The technology used in the studies included a microprocessor with

  11. Technology-Based Programs to Promote Walking Fluency or Improve Foot-Ground Contact during Walking: Two Case Studies of Adults with Multiple Disabilities

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; La Martire, Maria L.; Oliva, Doretta; Groeneweg, Jop

    2012-01-01

    These two case studies assessed technology-based programs for promoting walking fluency and improving foot-ground contact during walking with a man and a woman with multiple disabilities, respectively. The man showed breaks during walking and the woman presented with toe walking. The technology used in the studies included a microprocessor with…

  12. Prediction of walking speed using single stance force or pressure measurements in healthy subjects.

    PubMed

    Keijsers, N L W; Stolwijk, N M; Renzenbrink, G J; Duysens, J

    2016-01-01

    Walking speed is one of the best measures of overall walking capacity. In plantar pressure measurements, walking speed can be assessed using contact time, but it is only moderately correlated with walking speed. The center of pressure might be of more value to indicate walking speed since walking speed alters foot loading. Therefore, the purpose of this study is to assess walking speed using the velocity of the center of pressure (VCOP). Thirty-three subjects walked over a Footscan pressure plate at three speed conditions; slow, preferred, and fast. Walking speed was measured by a motion analysis system. (Multiple) linear regression analysis was used to indicate the relation between walking speed and independent variables derived from the pressure plate such as mean VCOP and stance time for all walking conditions separately and together. The mean VCOP had the highest correlation coefficient value with walking speed for all walking conditions combined (0.94) and for the preferred walking condition (0.80). The multiple regression analysis, based on a number of additional parameters, revealed a small to modest increase in the performance of predicting walking speed (r=0.98 for combined and r=0.93 for preferred). The mean VCOP was the best predictor for walking speed when using a plantar pressure plate. The mean VCOP predicts the walking speed with a 95% accuracy of 0.20m/s when healthy subjects walk at their preferred walking speed. PMID:26669958

  13. Chinese City Children and Youth's Walking Behavior

    ERIC Educational Resources Information Center

    Quan, Minghui; Chen, Peijie; Zhuang, Jie; Wang, Chao

    2013-01-01

    Purpose: Although walking has been demonstrated as one of the best forms for promoting physical activity (PA), little is known about Chinese city children and youth's walking behavior. The purpose of this study was therefore to assess ambulatory PA behavior of Chinese city children and youth. Method: The daily steps of 2,751 children and

  14. Human pair walking behavior: evaluation of cooperation strategies

    NASA Astrophysics Data System (ADS)

    Dobramysl, Ulrich; Bodova, Katarina; Kollar, Richard; Erban, Radek

    2015-03-01

    Human walkers are notoriously poor at keeping a direction without external cues: Experimental work by Souman et al. with blindfolded subjects told to walk in a straight line revealed intriguing circular and spiraling trajectories, which can be approximated by a stochastic process. In this work, motivated by pair walking experiments by Miglierini et al., we introduce an analysis of various strategies employed by a pair of blindfolded walkers, who are communicating via auditory cues, to maximize their efficiency at walking straight. To this end, we characterize pairs of strategies such as free walking, side-by-side walking and unconditional following from data generated by robot pair walking experiments (using computer vision techniques) and numerical simulations. We extract the mean exit distances of walker pairs from a corridor with finite width to construct phase portraits of the walking performance. We find intriguing cooperative effects leading to non-trivial enhancements of the efficiency at walking straight. The research leading to these results has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013) / ERC Grant Agreement No. 239870; and from the Royal Society through a Research Grant.

  15. GUD WIP: Gait-Understanding-Driven Walking-In-Place

    PubMed Central

    Wendt, Jeremy D.; Whitton, Mary C.; Brooks, Frederick P.

    2014-01-01

    Many Virtual Environments require walking interfaces to explore virtual worlds much larger than available real-world tracked space. We present a model for generating virtual locomotion speeds from Walking-In-Place (WIP) inputs based on walking biomechanics. By employing gait principles, our model – called Gait-Understanding-Driven Walking-In-Place (GUD WIP) – creates output speeds which better match those evident in Real Walking, and which better respond to variations in step frequency, including realistic starting and stopping. The speeds output by our implementation demonstrate considerably less within-step fluctuation than a good current WIP system – Low-Latency, Continuous-Motion (LLCM) WIP – while still remaining responsive to changes in user input. We compared resulting speeds from Real Walking, GUD WIP, and LLCM-WIP via user study: The average output speeds for Real Walking and GUD WIP respond consistently with changing step frequency – LLCM-WIP is far less consistent. GUD WIP produces output speeds that are more locally consistent (smooth) and step-frequency-to-walk-speed consistent than LLCM-WIP. PMID:25621313

  16. Infant Language Development Is Related to the Acquisition of Walking

    ERIC Educational Resources Information Center

    Walle, Eric A.; Campos, Joseph J.

    2014-01-01

    The present investigation explored the question of whether walking onset is related to infant language development. Study 1 used a longitudinal design (N = 44) to assess infant locomotor and language development every 2 weeks from 10 to 13.5 months of age. The acquisition of walking was associated with a significant increase in both receptive and

  17. Children's Physical Activity: The Contribution of Playing and Walking

    ERIC Educational Resources Information Center

    Mackett, Roger L.; Paskins, James

    2008-01-01

    This paper draws on research in which 200 children were fitted with motion sensors and asked to keep travel and activity diaries. The findings show that walking and playing away from home can contribute significantly to children's volume of physical activity, with consequent implications for their health. Not only do both playing and walking

  18. Promoting Discussion in the Science Classroom Using Gallery Walks

    ERIC Educational Resources Information Center

    Francek, Mark

    2006-01-01

    A gallery walk is a discussion technique that gets students out of their chairs and actively involved in synthesizing important science concepts, writing, and public speaking. The technique also cultivates listening and team-building skills. This paper provides guidance for conducting, managing, and assessing gallery walks. (Contains 4 tables and

  19. Validity of the Nike+ device during walking and running.

    PubMed

    Kane, N A; Simmons, M C; John, D; Thompson, D L; Bassett, D R; Basset, D R

    2010-02-01

    We determined the validity of the Nike+ device for estimating speed, distance, and energy expenditure (EE) during walking and running. Twenty trained individuals performed a maximal oxygen uptake test and underwent anthropometric and body composition testing. Each participant was outfitted with a Nike+ sensor inserted into the shoe and an Apple iPod nano. They performed eight 6-min stages on the treadmill, including level walking at 55, 82, and 107 m x min(-1), inclined walking (82 m x min(-1)) at 5 and 10% grades, and level running at 134, 161, and 188 m x min(-1). Speed was measured using a tachometer and EE was measured by indirect calorimetry. Results showed that the Nike+ device overestimated the speed of level walking at 55 m x min(-1) by 20%, underestimated the speed of level walking at 107 m x min(-1) by 12%, but closely estimated the speed of level walking at 82 m x min(-1), and level running at all speeds (p<0.05). Similar results were found for distance. The Nike+ device overestimated the EE of level walking by 18-37%, but closely estimated the EE of level running (p<0.05). In conclusion the Nike+ in-shoe device provided reasonable estimates of speed and distance during level running at the three speeds tested in this study. However, it overestimated EE during level walking and it did not detect the increased cost of inclined locomotion. PMID:20027538

  20. Walking in Beauty: An American Indian Perspective on Social Justice

    ERIC Educational Resources Information Center

    Eason, Evan Allen; Robbins, Rockey

    2012-01-01

    The purpose of this article is to introduce "walking in beauty," an American Indian spiritual perspective related to social justice that emphasizes beauty, harmony, connectedness/unity of experience, and imagination. Walking in beauty includes 3 processes: embodiment, creativity, and appreciation of the sublime. Recommendations are offered for

  1. Walking...A Step in the Right Direction!

    MedlinePLUS

    ... muscles help you burn more calories lift your mood Make walking fun by going to places you enjoy, like a park or shopping center. Bring along a friend or family member to chat with, or listen to some of your favorite music as you walk. Keep the volume low so ...

  2. Algebraic area enclosed by random walks on a lattice

    NASA Astrophysics Data System (ADS)

    Desbois, Jean

    2015-10-01

    We compute the moments ?ft<{A}2k\\right> of the area enclosed by an N-steps random walk on a 2D lattice. We consider separately the cases where the walk comes back to the origin or not. We also compute, for both cases, the characteristic function ?ft<{{{e}}}{{i} B A}\\right> at order 1/{N}2.

  3. Effect of Backward Walking on Attention: Possible Application on ADHD

    PubMed Central

    Viggiano, Davide; Travaglio, Michele; Cacciola, Giovanna; Di Costanzo, Alfonso

    2015-01-01

    The human requires attentive effort as assessed in dual-task experiments. Consistently, an attentive task can modify the walking pattern and a attention deficit and hyperactivity disorder (ADHD) is accompanied by gait modifications. Here we investigated the relationships between backward walking and attentive performances in ADHD children (n=13) and healthy age-, height and weight matched controls (n=17). We evaluated the attentive/impulsive profile by means of a Go/No-Go task and the backward and forward gait parameters by step length, cadence and Froude number. Moreover, to test the causal relationship between attention and gait parameters, we trained children to walk backward. The training program consisted of 10 min backward walking session, thrice a week for two months. Results showed a significant negative correlation between Froude number during backward walking and reaction time in the Go/No-Go test. Besides, after training with backward walking control children increased their cadence by 9.3% and their Froude number by 17% during backward walking. Conversely, ADHD children did not modify their walking parameters after training, and showed a significant reduction in their number of errors in the Go/No-Go task (?49%) compared to the score before the training. These data suggest that specific physical training with attention-demanding tasks may improve attentive performance. PMID:25674550

  4. Chinese City Children and Youth's Walking Behavior

    ERIC Educational Resources Information Center

    Quan, Minghui; Chen, Peijie; Zhuang, Jie; Wang, Chao

    2013-01-01

    Purpose: Although walking has been demonstrated as one of the best forms for promoting physical activity (PA), little is known about Chinese city children and youth's walking behavior. The purpose of this study was therefore to assess ambulatory PA behavior of Chinese city children and youth. Method: The daily steps of 2,751 children and…

  5. TIME-WALK CHARACTERISTICS OF AN IMPROVED CONSTANT FRACTION DISCRIMINATOR

    SciTech Connect

    Wozniak, G. J.; Richardson, L. W.; Maier, M. R.

    1980-09-01

    A modification to a constant fraction discriminator design published earlier makes the observed time walk less than 30 ps over an input voltage range of 0.15 to 2.5 V. This performance makes time-walk corrections unnecessary in many situations.

  6. The Fibonacci quantum walk and its classical trace map

    NASA Astrophysics Data System (ADS)

    Romanelli, A.

    2009-09-01

    We study the quantum walk in momentum space using a coin arranged in quasi-periodic sequences following a Fibonacci prescription. We build for this system a classical map based on the trace of the evolution operator. The sub-ballistic behavior of this quantum walk is connected with the power-law decay of the time correlations of the trace map.

  7. When does walking alter thinking? Age and task associated findings

    PubMed Central

    Srygley, Jennifer M; Mirelman, Anat; Herman, Talia; Giladi, Nir; Hausdorff, Jeffrey M

    2008-01-01

    Age-associated changes in gait are exacerbated when another task is performed simultaneously. We quantified the converse, i.e., the effects of walking on cognitive abilities, and determined the role of aging and executive function (EF) in any observed changes. 276 healthy older adults and 52 healthy young adults performed three cognitive tasks, i.e., serial 7 and 3 subtractions and phoneme-monitoring, while sitting and again while walking. Among the elderly, walking decreased performance on serial 3 and 7 subtractions and the number of phonemes counted (p<0.0001), but enhanced content recall. In contrast, for the young adults, walking did not alter serial 3 subtractions, phoneme-monitoring or content recall, while serial 7 subtraction performance decreased during walking (p=0.047). Measures of EF explained the age-associated changes in performance of the cognitive task during walking. Findings in both young and old subjects underscore the idea that gait is attention-demanding and is not a purely motor task. Even young, healthy adults demonstrate decreased cognitive performance while walking, when the cognitive task is sufficiently difficult. Age-associated declines in EF apparently contribute to the difference in dual tasking abilities during walking between young and older adults. PMID:19084511

  8. Quantum walk coherences on a dynamical percolation graph

    NASA Astrophysics Data System (ADS)

    Elster, Fabian; Barkhofen, Sonja; Nitsche, Thomas; Novotn, Jaroslav; Gbris, Aurl; Jex, Igor; Silberhorn, Christine

    2015-08-01

    Coherent evolution governs the behaviour of all quantum systems, but in nature it is often subjected to influence of a classical environment. For analysing quantum transport phenomena quantum walks emerge as suitable model systems. In particular, quantum walks on percolation structures constitute an attractive platform for studying open system dynamics of random media. Here, we present an implementation of quantum walks differing from the previous experiments by achieving dynamical control of the underlying graph structure. We demonstrate the evolution of an optical time-multiplexed quantum walk over six double steps, revealing the intricate interplay between the internal and external degrees of freedom. The observation of clear non-Markovian signatures in the coin space testifies the high coherence of the implementation and the extraordinary degree of control of all system parameters. Our work is the proof-of-principle experiment of a quantum walk on a dynamical percolation graph, paving the way towards complex simulation of quantum transport in random media.

  9. Simulation of energy consumption for quadruped walking vehicle

    NASA Astrophysics Data System (ADS)

    Lei, Jingtao; Gao, Feng; Xu, Guoyan

    2006-11-01

    Simulation of energy consumption for walking vehicle is one of the basic way to preliminarily estimate the energy that will be consumed before constructing the real vehicle, providing basis for the design of vehicle to minish energy consumption. One of the most influential factors of the accuracy dynamic simulation is the appropriate contact model between leg and ground. In this paper, we adopt virtual prototyping technique to develop the dynamic modeling of a quadruped walking vehicle considering contact force between legs and ground during walking, finish simulation of dynamics and obtain dynamics characteristics, investigate the effects of different contact condition and the energy consumption. The purpose is to analyze the relationship between energy consumption and relevant influence factors, and the energy efficiency during walking is discussed with different walking velocity, strokes, duty factors and different contact material. Moreover contact force is obtained from simulations. Commercial ADAMS package is used.

  10. Quantum walk in terms of quantum Bernoulli noises

    NASA Astrophysics Data System (ADS)

    Wang, Caishi; Ye, Xiaojuan

    2016-02-01

    Quantum Bernoulli noises are the family of annihilation and creation operators acting on Bernoulli functionals, which satisfy a canonical anti-commutation relation in equal time. In this paper, we first present some new results concerning quantum Bernoulli noises, which themselves are interesting. Then, based on these new results, we construct a time-dependent quantum walk with infinitely many degrees of freedom. We prove that the walk has a unitary representation and hence belongs to the category of the so-called unitary quantum walks. We examine its distribution property at the vacuum initial state and some other initial states and find that it has the same limit distribution as the classical random walk, which contrasts sharply with the case of the usual quantum walks with finite degrees of freedom.

  11. Radar walk detection in the apartments of elderly.

    PubMed

    Phillips, Calvin E; Keller, James; Popescu, Mihail; Skubic, Marjorie; Rantz, Marilyn J; Cuddihy, Paul E; Yardibi, Tarik

    2012-01-01

    Seniors want to live more independent lifestyles. This comes with some risks including dwindling health and major injuries due to falling. A factor that has been studied and seen to have a correlation to fall risk is change in gait speed. Our goal is to create a passive system that monitors the gait of elderly so that assessments can be given by caregivers if gait changes do occur. This paper will cover a method of using pulse-Doppler radar to detect when walks occur. In unscripted living environments, we are able to detect valid walks. The system does miss walks during the day, but when walks are detected, they are actually valid walks 91.8% of the time using a large data base of radar signals captured in living environments. PMID:23367262

  12. Phase transition in random adaptive walks on correlated fitness landscapes

    NASA Astrophysics Data System (ADS)

    Park, Su-Chan; Szendro, Ivan G.; Neidhart, Johannes; Krug, Joachim

    2015-04-01

    We study biological evolution on a random fitness landscape where correlations are introduced through a linear fitness gradient of strength c . When selection is strong and mutations rare the dynamics is a directed uphill walk that terminates at a local fitness maximum. We analytically calculate the dependence of the walk length on the genome size L . When the distribution of the random fitness component has an exponential tail, we find a phase transition of the walk length D between a phase at small c , where walks are short (D lnL ) , and a phase at large c , where walks are long (D L ) . For all other distributions only a single phase exists for any c >0 . The considered process is equivalent to a zero temperature Metropolis dynamics for the random energy model in an external magnetic field, thus also providing insight into the aging dynamics of spin glasses.

  13. Promoting Walking Among Older Adults Living in Retirement Communities

    PubMed Central

    Rosenberg, Dori E.; Kerr, Jacqueline; Sallis, James F.; Norman, Gregory J.; Calfas, Karen; Patrick, Kevin

    2013-01-01

    The authors tested the feasibility and acceptability, and explored the outcomes, of 2 walking interventions based on ecological models among older adults living in retirement communities. An enhanced intervention (EI) was compared with a standard walking intervention (SI) among residents in 4 retirement facilities (N = 87 at baseline; mean age = 84.1 yr). All participants received a walking intervention including pedometers, printed materials, and biweekly group sessions. EI participants also received phone counseling and environmental-awareness components. Measures included pedometer step counts, activities of daily living, environment-related variables, physical function, depression, cognitive function, satisfaction, and adherence. Results indicated improvements among the total sample for step counts, neighborhood barriers, cognitive function, and satisfaction with walking opportunities. Satisfaction and adherence were high. Both walking interventions were feasible to implement among facility-dwelling older adults. Future studies can build on this multilevel approach. PMID:22186798

  14. Promoting walking among older adults living in retirement communities.

    PubMed

    Rosenberg, Dori E; Kerr, Jacqueline; Sallis, James F; Norman, Gregory J; Calfas, Karen; Patrick, Kevin

    2012-07-01

    The authors tested the feasibility and acceptability, and explored the outcomes, of 2 walking interventions based on ecological models among older adults living in retirement communities. An enhanced intervention (EI) was compared with a standard walking intervention (SI) among residents in 4 retirement facilities (N = 87 at baseline; mean age = 84.1 yr). All participants received a walking intervention including pedometers, printed materials, and biweekly group sessions. EI participants also received phone counseling and environmental-awareness components. Measures included pedometer step counts, activities of daily living, environment-related variables, physical function, depression, cognitive function, satisfaction, and adherence. Results indicated improvements among the total sample for step counts, neighborhood barriers, cognitive function, and satisfaction with walking opportunities. Satisfaction and adherence were high. Both walking interventions were feasible to implement among facility-dwelling older adults. Future studies can build on this multilevel approach. PMID:22186798

  15. Checklist and Pollard Walk butterfly survey methods on public lands

    USGS Publications Warehouse

    Royer, R.A.; Austin, J.E.; Newton, W.E.

    1998-01-01

    Checklist and Pollard Walk butterfly survey methods were contemporaneously applied to seven public sites in North Dakota during the summer of 1995. Results were compared for effect of method and site on total number of butterflies and total number of species detected per hour. Checklist searching produced significantly more butterfly detections per hour than Pollard Walks at all sites. Number of species detected per hour did not differ significantly either among sites or between methods. Many species were detected by only one method, and at most sites generalist and invader species were more likely to be observed during checklist searches than during Pollard Walks. Results indicate that checklist surveys are a more efficient means for initial determination of a species list for a site, whereas for long-term monitoring the Pollard Walk is more practical and statistically manageable. Pollard Walk transects are thus recommended once a prairie butterfly fauna has been defined for a site by checklist surveys.

  16. 76 FR 33631 - Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-09

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY 10 CFR Part 431 RIN 1904-AB85 Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers Correction In rule document 2011-8690 appearing on pages 21579-21612 in the issue of Friday, April 15, 2011, the regulatory text is...

  17. Random time averaged diffusivities for Lvy walks

    NASA Astrophysics Data System (ADS)

    Froemberg, D.; Barkai, E.

    2013-07-01

    We investigate a Lvy walk alternating between velocities v0 with opposite sign. The sojourn time probability distribution at large times is a power law lacking its mean or second moment. The first case corresponds to a ballistic regime where the ensemble averaged mean squared displacement (MSD) at large times is ?x2? ? t2, the latter to enhanced diffusion with ?x2? ? t?, 1 < ? < 2. The correlation function and the time averaged MSD are calculated. In the ballistic case, the deviations of the time averaged MSD from a purely ballistic behavior are shown to be distributed according to a Mittag-Leffler density function. In the enhanced diffusion regime, the fluctuations of the time averages MSD vanish at large times, yet very slowly. In both cases we quantify the discrepancy between the time averaged and ensemble averaged MSDs.

  18. Quantum walk, entanglement and thermodynamic laws

    NASA Astrophysics Data System (ADS)

    Romanelli, Alejandro

    2015-09-01

    We consider a special dynamics of a quantum walk (QW) on a line. The walker, initially localized at the origin of the line with arbitrary chirality, evolves to an asymptotic stationary state. In this stationary state a measurement is performed and the state resulting from this measurement is used to start a second QW evolution to achieve a second asymptotic stationary state. In previous works, we developed the thermodynamics associated with the entanglement between the coin and position degrees of freedom in the QW. Here we study the application of the first and second laws of thermodynamics to the process between the two stationary states mentioned above. We show that: (i) the entropy change has upper and lower bounds that are obtained analytically as functions of the initial conditions. (ii) the energy change is associated to a heat-transfer process.

  19. Thermodynamics of N-dimensional quantum walks

    NASA Astrophysics Data System (ADS)

    Romanelli, Alejandro; Donangelo, Raul; Portugal, Renato; Marquezino, Franklin de Lima

    2014-08-01

    The entanglement between the position and the coin state of an N-dimensional quantum walker is shown to lead to a thermodynamic theory. The entropy, in this thermodynamics, is associated with the reduced density operator for the evolution of chirality, taking a partial trace over positions. From the asymptotic reduced density matrix it is possible to define thermodynamic quantities, such as the asymptotic entanglement entropy, temperature, and Helmholz free energy. We study in detail the case of a two-dimensional quantum walk, in the case of two initial conditions: a nonseparable coin-position initial state and a separable one. The resulting entanglement temperature is presented as a function of the parameters of the system and those of the initial conditions.

  20. The QWalk simulator of quantum walks

    NASA Astrophysics Data System (ADS)

    Marquezino, F. L.; Portugal, R.

    2008-09-01

    Several research groups are giving special attention to quantum walks recently, because this research area have been used with success in the development of new efficient quantum algorithms. A general simulator of quantum walks is very important for the development of this area, since it allows the researchers to focus on the mathematical and physical aspects of the research instead of deviating the efforts to the implementation of specific numerical simulations. In this paper we present QWalk, a quantum walk simulator for one- and two-dimensional lattices. Finite two-dimensional lattices with generic topologies can be used. Decoherence can be simulated by performing measurements or by breaking links of the lattice. We use examples to explain the usage of the software and to show some recent results of the literature that are easily reproduced by the simulator. Program summaryProgram title: QWalk Catalogue identifier: AEAX_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAX_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public Licence No. of lines in distributed program, including test data, etc.: 10 010 No. of bytes in distributed program, including test data, etc.: 172 064 Distribution format: tar.gz Programming language: C Computer: Any computer with a C compiler that accepts ISO C99 complex arithmetic (recent versions of GCC, for instance). Pre-compiled Windows versions are also provided Operating system: The software should run in any operating system with a recent C compiler. Successful tests were performed in Linux and Windows RAM: Less than 10 MB were required for a two-dimensional lattice of size 201×201. About 400 MB, for a two-dimensional lattice of size 1601×1601 Classification: 16.5 Nature of problem: Classical simulation of discrete quantum walks in one- and two-dimensional lattices. Solution method: Iterative approach without explicit representation of evolution operator. Restrictions: The available amount of RAM memory imposes a limit on the size of the simulations. Unusual features: The software provides an easy way of simulating decoherence through detectors or random broken links. In the two-dimensional simulations it also allows the definition of permanent broken links, besides calculation of total variation distance (from the uniform and from an approximate stationary distribution) and the choice between two different physical lattices. It also provides an easy way of performing measurements on specific sites of the 2D lattice and the analysis of observation screens. In one-dimensional simulations it allows the choice between three different lattices. Both one- and two-dimensional simulations facilitates the generation of graphics by automatically generating gnuplot scrips. Additional comments:An earlier version of QWalk was first presented in [1]. The simulator generates gnuplot scripts that can be used to make graphics of the output data. Several examples of input files are provided. Running time: The simulation of 100 steps for a two-dimensional lattice of size 201×201 took less than 2 seconds on a Pentium IV 2.6 GHz with 512 MB of RAM memory, 512 KB of cache memory and under Linux. It also took about 15 minutes for a lattice of size 1601×1601 on the same computer. Optimization option -O2 was used during compilation for these tests. References: [1] F.L. Marquezino, R. Portugal, QWalk: Simulador de caminhadas quânticas, in: Proceedings of 2nd WECIQ, Campina Grande, Brazil, IQuanta, 2007, pp. 123-132.

  1. Assessment of a Solar System Walk

    NASA Astrophysics Data System (ADS)

    Lopresto, Michael C.; Murrell, Steven R.; Kirchner, Brian

    2010-04-01

    The idea of sending students and the general public on a walk through a scale model of the solar system in an attempt to instill an appreciation of the relative scales of the sizes of the objects compared to the immense distances between them is certainly not new. A good number of such models exist, including one on the National Mall in Washington, D.C., starting at the Smithsonian Air and Space museum.1 A pioneering model and inspiration for our own is on the campus of the University of Colorado in Boulder,2 and there are others.3 Those at science museums are often used by the general public and field-trip groups, while the ones on college campuses are also used by students of introductory astronomy.

  2. Microscopic derivation of open quantum walks

    NASA Astrophysics Data System (ADS)

    Sinayskiy, Ilya; Petruccione, Francesco

    2015-09-01

    Open quantum walks (OQWs) are exclusively driven by dissipation and are formulated as completely positive trace-preserving (CPTP) maps on underlying graphs. The microscopic derivation of discrete and continuous-in-time OQWs is presented. It is assumed that connected nodes are weakly interacting via a common bath. The resulting reduced master equation of the quantum walker on the lattice is in the generalized master equation form. The time discretization of the generalized master equation leads to the OQW formalism. The explicit form of the transition operators establishes a connection between dynamical properties of the OQWs and thermodynamical characteristics of the environment. The derivation is demonstrated for the examples of the OQW on a circle of nodes and on a finite chain of nodes. For both examples, a transition between diffusive and ballistic quantum trajectories is observed and found to be related to the temperature of the bath.

  3. Exploring Toe Walking in a Bipedal Robot

    NASA Astrophysics Data System (ADS)

    Smith, James Andrew; Seyfarth, Andre

    The design and development of locomotory subsystems such as legs is a key issue in the broader topic of autonomous mobile systems. Simplification of substructures, sensing, actuation and control can aid to better understand the dynamics of legged locomotion and will make the implementation of legs in engineered systems more effective. This paper examines recent results in the development of toe walking on the JenaWalker II robot. The robot is shown, while supported on a treadmill, to be capable of accelerating from 0 to over 0.6 m/s without adjustment of control parameters such as hip actuator sweep frequency or amplitude. The resulting stable motion is due to the adaptability of the passive structures incorporated into the legs. The roles of the individual muscletendon groups are examined and a potential configuration for future heel-toe trials is suggested.

  4. The subtle nature of financial random walks

    NASA Astrophysics Data System (ADS)

    Bouchaud, Jean-Philippe

    2005-06-01

    We first review the most important "stylized facts" of financial time series, that turn out to be, to a large extent, universal. We then recall how the multifractal random walk of Bacry, Muzy, and Delour generalizes the standard model of financial price changes and accounts in an elegant way for many of their empirical properties. In a second part, we provide empirical evidence for a very subtle compensation mechanism that underlies the random nature of price changes. This compensation drives the market close to a critical point, that may explain the sensitivity of financial markets to small perturbations, and their propensity to enter bubbles and crashes. We argue that the resulting unpredictability of price changes is very far from the neoclassical view that markets are informationally efficient.

  5. Lower and upper extremity loading in nordic walking in comparison with walking and running.

    PubMed

    Hagen, Marco; Hennig, Ewald M; Stieldorf, Peter

    2011-02-01

    Nordic walking (NW) was compared with walking (W) and running (R) with respect to upper and lower limb injury risks. 24 NW-instructors performed W, NW, and R trials on a runway covered with artificial turf at controlled speeds. Foot pronation and ground reaction forces were measured as well as shock wave transmission to the right wrist. Comparison of NW and W shows similar results for all of the four chosen velocities (5 km/h, 7 km/h, 8 km/h, 8.5 km/h). Except for the 2nd peak of the vertical ground reaction force, NW results in higher loading rates and horizontal forces as well as higher pronation and pronation velocity values as compared with W. Wrist acceleration values up to 7.6 times gravitational acceleration were recorded in NW. Compared with R at the same speeds (8 km/h and 8.5 km/h), NW can be recommended as low impact sport with 36% lower loading rates and 59% lower pronation velocities. However, the high wrist accelerations in NW reveal that the upper extremities are exposed to considerable repetitive shocks, which may cause overuse injuries of the upper extremities. Thus, additional preventive exercises for the upper limb muscles are recommended as well as using shock absorbing walking poles. PMID:21451179

  6. Demand response to improved walking infrastructure: A study into the economics of walking and health behaviour change.

    PubMed

    Longo, Alberto; Hutchinson, W George; Hunter, Ruth F; Tully, Mark A; Kee, Frank

    2015-10-01

    Walking is the most common form of moderate-intensity physical activity among adults, is widely accessible and especially appealing to obese people. Most often policy makers are interested in valuing the effect on walking of changes in some characteristics of a neighbourhood, the demand response for walking, of infrastructure changes. A positive demand response to improvements in the walking environment could help meet the public health target of 150 min of at least moderate-intensity physical activity per week. We model walking in an individual's local neighbourhood as a 'weak complement' to the characteristics of the neighbourhood itself. Walking is affected by neighbourhood characteristics, substitutes, and individual's characteristics, including their opportunity cost of time. Using compensating variation, we assess the economic benefits of walking and how walking behaviour is affected by improvements to the neighbourhood. Using a sample of 1209 respondents surveyed over a 12 month period (Feb 2010-Jan 2011) in East Belfast, United Kingdom, we find that a policy that increased walkability and people's perception of access to shops and facilities would lead to an increase in walking of about 36 min/person/week, valued at 13.65/person/week. When focussing on inactive residents, a policy that improved the walkability of the area would lead to guidelines for physical activity being reached by only 12.8% of the population who are currently inactive. Additional interventions would therefore be needed to encourage inactive residents to achieve the recommended levels of physical activity, as it appears that interventions that improve the walkability of an area are particularly effective in increasing walking among already active citizens, and, among the inactive ones, the best response is found among healthier, younger and wealthier citizens. PMID:26347960

  7. Automaticity of walking: functional significance, mechanisms, measurement and rehabilitation strategies.

    PubMed

    Clark, David J

    2015-01-01

    Automaticity is a hallmark feature of walking in adults who are healthy and well-functioning. In the context of walking, "automaticity" refers to the ability of the nervous system to successfully control typical steady state walking with minimal use of attention-demanding executive control resources. Converging lines of evidence indicate that walking deficits and disorders are characterized in part by a shift in the locomotor control strategy from healthy automaticity to compensatory executive control. This is potentially detrimental to walking performance, as an executive control strategy is not optimized for locomotor control. Furthermore, it places excessive demands on a limited pool of executive reserves. The result is compromised ability to perform basic and complex walking tasks and heightened risk for adverse mobility outcomes including falls. Strategies for rehabilitation of automaticity are not well defined, which is due to both a lack of systematic research into the causes of impaired automaticity and to a lack of robust neurophysiological assessments by which to gauge automaticity. These gaps in knowledge are concerning given the serious functional implications of compromised automaticity. Therefore, the objective of this article is to advance the science of automaticity of walking by consolidating evidence and identifying gaps in knowledge regarding: (a) functional significance of automaticity; (b) neurophysiology of automaticity; PMID:25999838

  8. Effects of galvanic vestibular stimulation during human walking

    PubMed Central

    Fitzpatrick, Richard C; Wardman, Daniel L; Taylor, Janet L

    1999-01-01

    To identify vestibular influences on human walking, galvanic vestibular stimulation was applied to normal adult subjects as they walked to a previously seen target. A transmastoidal step stimulus commenced as subjects started walking. With the eyes shut, the galvanic stimulus caused large turns towards the side with the anodal current. Ability to perceive the trajectory of gait without visual cues was measured by guiding blindfolded subjects from one arbitrary point to another, either walking or seated in a wheelchair. On reaching a destination position and removing the blindfold, subjects pointed to indicate the starting position. Subjects made considerable errors in estimating the trajectory, but were equally accurate whether in the wheelchair or walking. To determine the effects of vestibular stimulation on the perception of trajectory, the galvanic stimulus was applied to blindfolded subjects as they were guided from one point to another in the wheelchair. The vestibular stimulus produced an illusory shift in the trajectory travelled. This shift was towards the side with the cathode, i.e. in the opposite direction to the turn produced by the stimulus during walking. We conclude that galvanic vestibular stimulation during walking causes subjects to turn from their planned trajectory. In part, this altered course may compensate for an altered perception of trajectory produced by the stimulus. However, altered perception of the vertical or the base of support, or direct vestibulo-fugal influences on the leg muscles could contribute to the changes in gait. PMID:10358131

  9. Endurance shuttle walking test: responsiveness to salmeterol in COPD.

    PubMed

    Brouillard, C; Pepin, V; Milot, J; Lacasse, Y; Maltais, F

    2008-03-01

    Few studies have shown that the endurance shuttle walking test (ESWT) is responsive to treatment in patients with chronic obstructive pulmonary disease (COPD). This exercise test needs to be further investigated because of its relevance for activity of daily living. The aim of the present study was to evaluate, in patients with COPD, the responsiveness of the ESWT in detecting improvement in walking performance after a single dose of salmeterol. In a randomised, double-blind, placebo-controlled crossover trial, 20 patients with COPD performed two ESWT at 80% of peak capacity 2.5 h after inhaling either a placebo or 50 microg of salmeterol. Cardiorespiratory parameters were monitored during each walking test. Inspiratory capacities and Borg ratings for dyspnoea were obtained every other minute throughout the tests. Compared with placebo, salmeterol produced a significant change in lung function and a significant improvement in walking performance (mean+/-sd difference in time: 117+/-20 s; difference in distance: 160+/-277 m). At isotime (the latest exercise time that was reached on both ESWT), a significant reduction in dyspnoea was observed after bronchodilation. Bronchodilation with salmeterol reduced dyspnoea during walking and improved walking capacity in patients with chronic obstructive pulmonary disease. These findings provide further support for the use of the endurance shuttle walking test as an evaluative tool in chronic obstructive pulmonary disease. PMID:18057052

  10. Automaticity of walking: functional significance, mechanisms, measurement and rehabilitation strategies

    PubMed Central

    Clark, David J.

    2015-01-01

    Automaticity is a hallmark feature of walking in adults who are healthy and well-functioning. In the context of walking, “automaticity” refers to the ability of the nervous system to successfully control typical steady state walking with minimal use of attention-demanding executive control resources. Converging lines of evidence indicate that walking deficits and disorders are characterized in part by a shift in the locomotor control strategy from healthy automaticity to compensatory executive control. This is potentially detrimental to walking performance, as an executive control strategy is not optimized for locomotor control. Furthermore, it places excessive demands on a limited pool of executive reserves. The result is compromised ability to perform basic and complex walking tasks and heightened risk for adverse mobility outcomes including falls. Strategies for rehabilitation of automaticity are not well defined, which is due to both a lack of systematic research into the causes of impaired automaticity and to a lack of robust neurophysiological assessments by which to gauge automaticity. These gaps in knowledge are concerning given the serious functional implications of compromised automaticity. Therefore, the objective of this article is to advance the science of automaticity of walking by consolidating evidence and identifying gaps in knowledge regarding: (a) functional significance of automaticity; (b) neurophysiology of automaticity; (c) measurement of automaticity; (d) mechanistic factors that compromise automaticity; and (e) strategies for rehabilitation of automaticity. PMID:25999838

  11. Behavior Change Techniques Used to Promote Walking and Cycling

    PubMed Central

    Bird, Emma L.; Baker, Graham; Mutrie, Nanette; Ogilvie, David; Sahlqvist, Shannon; Powell, Jane

    2013-01-01

    Objective: Evidence on the effectiveness of walking and cycling interventions is mixed. This may be partly attributable to differences in intervention content, such as the cognitive and behavioral techniques (BCTs) used. Adopting a taxonomy of BCTs, this systematic review addressed two questions: (a) What are the behavior change techniques used in walking and cycling interventions targeted at adults? (b) What characterizes interventions that appear to be associated with changes in walking and cycling in adults? Method: Previous systematic reviews and updated database searches were used to identify controlled studies of individual-level walking and cycling interventions involving adults. Characteristics of intervention design, context, and methods were extracted in addition to outcomes. Intervention content was independently coded according to a 26-item taxonomy of BCTs. Results: Studies of 46 interventions met the inclusion criteria. Twenty-one reported a statistically significant effect on walking and cycling outcomes. Analysis revealed substantial heterogeneity in the vocabulary used to describe intervention content and the number of BCTs coded. “Prompt self-monitoring of behavior” and “prompt intention formation” were the most frequently coded BCTs. Conclusion: Future walking and cycling intervention studies should ensure that all aspects of the intervention are reported in detail. The findings lend support to the inclusion of self-monitoring and intention formation techniques in future walking and cycling intervention design, although further exploration of these and other BCTs is required. Further investigation of the interaction between BCTs and study design characteristics would also be desirable. PMID:23477577

  12. Simulation Studies of Bipedal Walking on the Moon and Mars

    NASA Astrophysics Data System (ADS)

    Yamada, Shin; Ohshima, Hiroshi; Yamaguchi, Tomofumi; Narukawa, Terumasa; Takahashi, Masaki; Hase, Kimitaka; Liu, Meigen; Mukai, Chiaki

    In order to walk upright on the Moon or Mars without falling, a specific walking strategy to account for altered gravitational conditions must be verified. We have therefore been studying changes in the kinematics of walking at different gravitational loads using a body weight suspension system. Our simulation consisted of three gravitational conditions: 1 g (Earth); 1/3 g (Mars); and 1/6 g (the Moon). Surface EMG recordings were taken from the leg muscles of subjects walking on a treadmill. Cadence, stance phase duration, and step length were calculated from the walking velocity and steps. Subsequent experiments revealed that muscle activity and the duration of the double support phase decreased as simulated gravity was reduced. These changes are apparently caused not only by the direct effects of unloading but also by kinematic adaptations to the same. It can be said that humans walk slowly with a shortened stride and elongated stance phase in order to adjust to low gravitational conditions. One major limitation of our study that may have affected walking stability was the fact that the suspension system was fixed to an immovable frame. We have begun further studies using a newer movable body weight suspension system to achieve more realistic simulations.

  13. Electrocortical activity distinguishes between uphill and level walking in humans.

    PubMed

    Bradford, J Cortney; Lukos, Jamie R; Ferris, Daniel P

    2016-02-01

    The objective of this study was to determine if electrocortical activity is different between walking on an incline compared with level surface. Subjects walked on a treadmill at 0% and 15% grades for 30 min while we recorded electroencephalography (EEG). We used independent component (IC) analysis to parse EEG signals into maximally independent sources and then computed dipole estimations for each IC. We clustered cortical source ICs and analyzed event-related spectral perturbations synchronized to gait events. Theta power fluctuated across the gait cycle for both conditions, but was greater during incline walking in the anterior cingulate, sensorimotor and posterior parietal clusters. We found greater gamma power during level walking in the left sensorimotor and anterior cingulate clusters. We also found distinct alpha and beta fluctuations, depending on the phase of the gait cycle for the left and right sensorimotor cortices, indicating cortical lateralization for both walking conditions. We validated the results by isolating movement artifact. We found that the frequency activation patterns of the artifact were different than the actual EEG data, providing evidence that the differences between walking conditions were cortically driven rather than a residual artifact of the experiment. These findings suggest that the locomotor pattern adjustments necessary to walk on an incline compared with level surface may require supraspinal input, especially from the left sensorimotor cortex, anterior cingulate, and posterior parietal areas. These results are a promising step toward the use of EEG as a feed-forward control signal for ambulatory brain-computer interface technologies. PMID:26683062

  14. Walking guide robot with tactile display for the blind

    NASA Astrophysics Data System (ADS)

    Yoon, Myoung-Jong; Yu, Kee-Ho; Kang, Jeong-Ho; Kim, Nam-Gyun

    2005-12-01

    A prototype of a walking guide robot with tactile display was introduced, and the psychophysical experiment of the tactile recognition for a tactile display was carried out and analyzed. The objective of this research is the development of a walking guide robot for the blind to walk safely. The walking guide robot consists of a guide vehicle for the obstacle detection and a tactile display device for the transfer of the obstacle information. The guide vehicle, located in the front of the walking blind, detects the obstacle using ultrasonic and infrared ray sensors. The processed information makes a obstacle map and transmits safe path and emergency situation to the blind by the tactile display. The guide vehicle offers the information of position and walking direction acquired from GPS module to the walking blind by voice. The tactile display device, located in the handle which is connected with the guide vehicle by cane, offers the processed obstacle information such as position, size, moving, shape of obstacle and safe path, etc.. The psychophysical experiments for the threshold of perception and recognition ability of tactile stimulation were carried out by the estimation of the subject group. As a result, the appropriate tactile stimulus intensity and frequency to recognize tactile stimulation effectively were discussed and derived.

  15. Walking and running in the desert ant Cataglyphis fortis.

    PubMed

    Wahl, Verena; Pfeffer, Sarah E; Wittlinger, Matthias

    2015-06-01

    Path integration, although inherently error-prone, is a common navigation strategy in animals, particularly where environmental orientation cues are rare. The desert ant Cataglyphis fortis is a prominent example, covering large distances on foraging excursions. The stride integrator is probably the major source of path integration errors. A detailed analysis of walking behaviour in Cataglyphis is thus of importance for assessing possible sources of errors and potential compensation strategies. Zollikofer (J Exp Biol 192:95-106, 1994a) demonstrated consistent use of the tripod gait in Cataglyphis, and suggested an unexpectedly constant stride length as a possible means of reducing navigation errors. Here, we extend these studies by more detailed analyses of walking behaviour across a large range of walking speeds. Stride length increases linearly and stride amplitude of the middle legs increases slightly linearly with walking speed. An initial decrease of swing phase duration is observed at lower velocities with increasing walking speed. Then it stays constant across the behaviourally relevant range of walking speeds. Walking speed is increased by shortening of the stance phase and of the stance phase overlap. At speeds larger than 370 mm s(-1), the stride frequency levels off, the duty factor falls below 0.5, and Cataglyphis transitions to running with aerial phases. PMID:25829304

  16. Analysis of the two-particle controlled interacting quantum walks

    NASA Astrophysics Data System (ADS)

    Li, Dan; Zhang, Jie; Ma, Xiu-Wen; Zhang, Wei-Wei; Wen, Qiao-Yan

    2013-06-01

    We have recently proposed the two-particle controlled interacting quantum walks for building quantum Hash schemes (Li et al. Quantum Inf Proc, 2012. doi:10.1007/s11128-012-0421-8). In this paper, we adopt the mutual information, the measurement-induced disturbance and the quantum mutual information to measure the classical correlation, the quantum correlation and the total correlation between two particles respectively. Our conclusion is that the correlation between the particles of the two-particle controlled interacting quantum walks is similar to that of the two-particle interacting quantum walks. It is superb for keeping the quantum Hash scheme safe.

  17. Perception, planning, and control for walking on rugged terrain

    NASA Technical Reports Server (NTRS)

    Simmons, Reid; Krotkov, Eric

    1991-01-01

    The CMU Planetary Rover project is developing a six-legged walking robot capable of autonomously navigating, exploring, and acquiring samples in rugged, unknown environments. To gain experience with the problems involved in walking on rugged terrain, a full-scale prototype leg was built and mounted on a carriage that rolls along overhead rails. Issues addressed in developing the software system to autonomously walk the leg through rugged terrain are described. In particular, the insights gained into perceiving and modeling rugged terrain, controlling the legged mechanism, interacting with the ground, choosing safe yet effective footfalls, and planning efficient leg moves through space are described.

  18. Quantization and asymptotic behaviour of ? quantum random walk on integers

    NASA Astrophysics Data System (ADS)

    Ellinas, Demosthenes; Smyrnakis, Ioannis

    2006-06-01

    Quantization and asymptotic behaviour of a variant of discrete random walk on integers are investigated. This variant, the ? walk, has the novel feature that it uses many identical quantum coins keeping at the same time characteristic quantum features like the quadratically faster than the classical spreading rate, and unexpected distribution cutoffs. A weak limit of the position probability distribution (pd) is obtained, and universal properties of this arch sine asymptotic distribution function are examined. Questions of driving the walk are investigated by means of a quantum optical interaction model that reveals robustness of quantum features of walker's asymptotic pd, against stimulated and spontaneous quantum noise on the coin system.

  19. Quantum walk on the line through potential barriers

    NASA Astrophysics Data System (ADS)

    Wong, Thomas G.

    2016-02-01

    Quantum walks are well known for their ballistic dispersion, traveling Θ (t) away in t steps, which is quadratically faster than a classical random walk's diffusive spreading. In physical implementations of the walk, however, the particle may need to tunnel through a potential barrier to hop, and a naive calculation suggests that this could eliminate the ballistic transport. We show by explicit calculation, however, that such a loss does not occur. Rather, the Θ (t) dispersion is retained, with only the coefficient changing, which additionally gives a way to detect and quantify the hopping errors in experiments.

  20. Decoherence in a one-dimensional quantum walk

    SciTech Connect

    Annabestani, Mostafa; Abolhassani, Mohamad Reza; Akhtarshenas, Seyed Javad

    2010-03-15

    In this article we study decoherence in the discrete-time quantum walk on the line. We generalize the method of decoherent coin quantum walk, introduced by Brun et al. [Phys. Rev. A 67, 32304 (2003)]. Our analytical expressions are applicable for all kinds of decoherence. As an example of the coin-position decoherence, we study the broken line quantum walk and compare our results with the numerical one. We also show that our analytical results reduce to the Brun formalism when only the coin is subjected to decoherence.

  1. Activity patterns and timing of muscle activity in the forward walking and backward walking stick insect Carausius morosus.

    PubMed

    Rosenbaum, Philipp; Wosnitza, Anne; Bschges, Ansgar; Gruhn, Matthias

    2010-09-01

    Understanding how animals control locomotion in different behaviors requires understanding both the kinematics of leg movements and the neural activity underlying these movements. Stick insect leg kinematics differ in forward and backward walking. Describing leg muscle activity in these behaviors is a first step toward understanding the neuronal basis for these differences. We report here the phasing of EMG activities and latencies of first spikes relative to precise electrical measurements of middle leg tarsus touchdown and liftoff of three pairs (protractor/retractor coxae, levator/depressor trochanteris, extensor/flexor tibiae) of stick insect middle leg antagonistic muscles that play central roles in generating leg movements during forward and backward straight walking. Forward walking stance phase muscle (depressor, flexor, and retractor) activities were tightly coupled to touchdown, beginning on average 93 ms prior to and 9 and 35 ms after touchdown, respectively. Forward walking swing phase muscle (levator, extensor, and protractor) activities were less tightly coupled to liftoff, beginning on average 100, 67, and 37 ms before liftoff, respectively. In backward walking the protractor/retractor muscles reversed their phasing compared with forward walking, with the retractor being active during swing and the protractor during stance. Comparison of intact animal and reduced two- and one-middle-leg preparations during forward straight walking showed only small alterations in overall EMG activity but changes in first spike latencies in most muscles. Changing body height, most likely due to changes in leg joint loading, altered the intensity, but not the timing, of depressor muscle activity. PMID:20668273

  2. Walking, running, and resting under time, distance, and average speed constraints: optimality of walkrunrest mixtures

    PubMed Central

    Long, Leroy L.; Srinivasan, Manoj

    2013-01-01

    On a treadmill, humans switch from walking to running beyond a characteristic transition speed. Here, we study human choice between walking and running in a more ecological (non-treadmill) setting. We asked subjects to travel a given distance overground in a given allowed time duration. During this task, the subjects carried, and could look at, a stopwatch that counted down to zero. As expected, if the total time available were large, humans walk the whole distance. If the time available were small, humans mostly run. For an intermediate total time, humans often use a mixture of walking at a slow speed and running at a higher speed. With analytical and computational optimization, we show that using a walkrun mixture at intermediate speeds and a walkrest mixture at the lowest average speeds is predicted by metabolic energy minimization, even with costs for transientsa consequence of non-convex energy curves. Thus, sometimes, steady locomotion may not be energy optimal, and not preferred, even in the absence of fatigue. Assuming similar non-convex energy curves, we conjecture that similar walkrun mixtures may be energetically beneficial to children following a parent and animals on long leashes. Humans and other animals might also benefit energetically from alternating between moving forward and standing still on a slow and sufficiently long treadmill. PMID:23365192

  3. Treadmill Adaptation and Verification of Self-Selected Walking Speed: A Protocol for Children

    ERIC Educational Resources Information Center

    Amorim, Paulo Roberto S.; Hills, Andrew; Byrne, Nuala

    2009-01-01

    Walking is a common activity of daily life and researchers have used the range 3-6 km.h[superscript -1] as reference for walking speeds habitually used for transportation. The term self-selected (i.e., individual or comfortable walking pace or speed) is commonly used in the literature and is identified as the most efficient walking speed, with…

  4. The Effects of a 12-Week Walking Program on Community-Dwelling Older Adults

    ERIC Educational Resources Information Center

    Cheng, Shun-Ping; Tsai, Tzu-I; Lii, Yun-Kung; Yu, Shu; Chou, Chen-Liang; Chen, I-Ju

    2009-01-01

    Walking is a popular and easily accessible form of physical activity. However, walking instruction for older adults is based on the evidence gathered from younger populations. This study evaluated walking conditions, strength, balance, and subjective health status after a 12-week walking-training program in community-dwelling adults greater than

  5. Identifying Belief-Based Targets for the Promotion of Leisure-Time Walking

    ERIC Educational Resources Information Center

    Rhodes, Ryan E.; Blanchard, Chris M.; Courneya, Kerry S.; Plotnikoff, Ronald C.

    2009-01-01

    Walking is the most common type of physical activity (PA) and the likely target of efforts to increase PA. No studies, however, have identified the belief-level correlates for walking using the theory of planned behavior. This study elicits salient beliefs about walking and evaluates beliefs that may be most important for walking-promotion

  6. Impact of railroad ballast type on frontal plane ankle kinematics during walking.

    PubMed

    Andres, Robert O; Holt, Kenneth G; Kubo, Masayoshi

    2005-09-01

    Five healthy male subjects walked on a control surface (level concrete), and two sloped rock surfaces (walking ballast-rock about 1.9 cm across; main line ballast-rock about 3.8 cm across) while their rearfoot motion (defined throughout as ankle inversion/eversion as seen from the frontal plane) was measured to determine if the different walking surfaces caused different ankle kinematics. The ballast was placed in 5m long trays that were tilted 7 degrees in the transverse plane. Rearfoot motion was measured while the subjects walked the length of the respective surfaces wearing work boots. A repeated measures ANOVA and a subsequent multiple comparison test revealed that the rearfoot range of motion was significantly greater walking on the main line ballast than walking on either the walking ballast or the level concrete. Meanwhile, the mean range of rearfoot motion for walking ballast was not significantly different from that resulting from walking on concrete. Variability was more than twice as great walking on main line ballast than walking on level concrete. Rearfoot angular velocities walking on level concrete and walking ballast were not significantly different, but both were significantly less than walking on main line ballast. Results suggested that rearfoot motion could be reduced if railroads placed walking ballast where trainmen have to walk as part of their jobs. PMID:15894284

  7. Vaulting mechanics successfully predict decrease in walk-run transition speed with incline.

    PubMed

    Hubel, Tatjana Y; Usherwood, James R

    2013-04-23

    There is an ongoing debate about the reasons underlying gait transition in terrestrial locomotion. In bipedal locomotion, the 'compass gait', a reductionist model of inverted pendulum walking, predicts the boundaries of speed and step length within which walking is feasible. The stance of the compass gait is energetically optimal-at walking speeds-owing to the absence of leg compression/extension; completely stiff limbs perform no work during the vaulting phase. Here, we extend theoretical compass gait vaulting to include inclines, and find good agreement with previous observations of changes in walk-run transition speed (approx. 1% per 1% incline). We measured step length and frequency for humans walking either on the level or up a 9.8 per cent incline and report preferred walk-run, walk-compliant-walk and maximum walk-run transition speeds. While the measured 'preferred' walk-run transition speed lies consistently below the predicted maximum walking speeds, and 'actual' maximum walking speeds are clearly above the predicted values, the onset of compliant walking in level as well as incline walking occurs close to the predicted values. These findings support the view that normal human walking is constrained by the physics of vaulting, but preferred absolute walk-run transition speeds may be influenced by additional factors. PMID:23325739

  8. Treadmill Adaptation and Verification of Self-Selected Walking Speed: A Protocol for Children

    ERIC Educational Resources Information Center

    Amorim, Paulo Roberto S.; Hills, Andrew; Byrne, Nuala

    2009-01-01

    Walking is a common activity of daily life and researchers have used the range 3-6 km.h[superscript -1] as reference for walking speeds habitually used for transportation. The term self-selected (i.e., individual or comfortable walking pace or speed) is commonly used in the literature and is identified as the most efficient walking speed, with

  9. The Effects of a 12-Week Walking Program on Community-Dwelling Older Adults

    ERIC Educational Resources Information Center

    Cheng, Shun-Ping; Tsai, Tzu-I; Lii, Yun-Kung; Yu, Shu; Chou, Chen-Liang; Chen, I-Ju

    2009-01-01

    Walking is a popular and easily accessible form of physical activity. However, walking instruction for older adults is based on the evidence gathered from younger populations. This study evaluated walking conditions, strength, balance, and subjective health status after a 12-week walking-training program in community-dwelling adults greater than…

  10. A scaling law for random walks on networks

    PubMed Central

    Perkins, Theodore J.; Foxall, Eric; Glass, Leon; Edwards, Roderick

    2014-01-01

    The dynamics of many natural and artificial systems are well described as random walks on a network: the stochastic behaviour of molecules, traffic patterns on the internet, fluctuations in stock prices and so on. The vast literature on random walks provides many tools for computing properties such as steady-state probabilities or expected hitting times. Previously, however, there has been no general theory describing the distribution of possible paths followed by a random walk. Here, we show that for any random walk on a finite network, there are precisely three mutually exclusive possibilities for the form of the path distribution: finite, stretched exponential and power law. The form of the distribution depends only on the structure of the network, while the stepping probabilities control the parameters of the distribution. We use our theory to explain path distributions in domains such as sports, music, nonlinear dynamics and stochastic chemical kinetics. PMID:25311870

  11. Erections on walking as a symptom of spinal canal stenosis.

    PubMed Central

    Hopkins, A; Clarke, C; Brindley, G

    1987-01-01

    Two patients reported that on walking they developed tingling and weakness of the legs and penile erections. The symptoms proved to be due to stenosis of the lumbar were canal, and were relieved by operative decompression. Images PMID:3681316

  12. a Novel Sideway Stability Control Method for Bipedal Walking Robot

    NASA Astrophysics Data System (ADS)

    Jo, H. Siswoyo; Mir-Nasiri, N.

    2011-06-01

    This paper presents a novel sensing and balancing method for bipedal walking robot. The proposed method involves the design of semi-rigid ankle joint to facilitate the responsive and accurate measurement of the sideway (sagittal) instability of the walking robot. The use of double balancing mass and the developed control algorithms provide a constant sideway stability of the robot while it walks in forward direction. The smooth legs trajectory planning then can be implemented successfully regardless of the robot sideway stability condition. The developed method is able to decouple the walking algorithms from the robot stability issues. Furthermore, the use of two different masses for the balancing helps to improve response time and efficiency of the balancing system. In this paper, the proposed method is tested on the simplified model of a robot balancing on its single leg and the feasibility of the method is confirmed by the simulation results obtained with MATLAB Simulink tools.

  13. Kinematic parameters of sheep walking on a treadmill.

    PubMed

    Valentin, Stephanie; Essigbeck, Annika; Wolfram, Ines; Licka, Theresia

    2014-12-01

    Ovine locomotion studies are rare, despite their relevance for medical research. The aim of this preliminary study was to investigate habituation and temporospatial parameters during treadmill walking of seven Austrian Mountain sheep. Sheep were naïve to treadmill exercise. During five treadmill sessions, movement cycle duration (MCD), vertical trunk movement (VTM), stride height (SH), stride length (SL), and percentage of movement cycle at stance (%St) were assessed. Two sheep were excluded from the study because they would not walk on the treadmill. From the end measurement session, MCD (0.95 s) and %St (62%) were similar to reported kinetics of sheep walking over ground, although stride length (1.05 m) was longer in this study. These findings suggest that sheep may require more than five sessions to become habituated to treadmill walking. PMID:25457259

  14. Record statistics of financial time series and geometric random walks.

    PubMed

    Sabir, Behlool; Santhanam, M S

    2014-09-01

    The study of record statistics of correlated series in physics, such as random walks, is gaining momentum, and several analytical results have been obtained in the past few years. In this work, we study the record statistics of correlated empirical data for which random walk models have relevance. We obtain results for the records statistics of select stock market data and the geometric random walk, primarily through simulations. We show that the distribution of the age of records is a power law with the exponent α lying in the range 1.5≤α≤1.8. Further, the longest record ages follow the Fréchet distribution of extreme value theory. The records statistics of geometric random walk series is in good agreement with that obtained from empirical stock data. PMID:25314414

  15. For a Better Calorie Burn, Adjust Your Speed While Walking

    MedlinePLUS

    ... medlineplus/news/fullstory_155127.html For a Better Calorie Burn, Adjust Your Speed While Walking Stopping and ... This caloric cost is often not included in calorie-burning estimations, Srinivasan's group said. Study lead author ...

  16. Self-Guided Walking Tours to Teach Orientation.

    ERIC Educational Resources Information Center

    Anderson, Jeremy

    1986-01-01

    Provides 2 examples of walking tours developed for primary grade children. The first example is map-based and the second is a verbal treasure hunt exercise where students follow a series of instructions to move about their school. (JDH)

  17. Measurement of pressure walking in footwear used in leprosy.

    PubMed

    Birke, J A; Foto, J G; Deepak, S; Watson, J

    1994-09-01

    Pressure measurements were made on 10 leprosy patients while walking barefoot and while using 6 sample shoes. The sample shoes, which represented footwear currently used worldwide in leprosy programmes, included: 1, a USA extradepth shoe without insole; 2, a USA extradepth shoe with insole; 3, a Chinese tennis shoe; 4, a Mozambique sandal; 5, a Bombay sandal; 6, a Bombay sandal with rigid sole; and 7, the patients' prescribed footwear. Peak pressure was significantly lower while walking in all footwear, except with the extradepth shoe without an insole, when compared to barefoot walking. Peak pressure was significantly lower walking in the Bombay sandals, the Chinese tennis shoe, the extradepth shoe with an insert and the patients' prescribed shoe when compared to the extradepth shoe without an insert. Regression analysis showed a significant inverse relationship between pressure and insole thickness (P < 0.001, R2 = 0.17). PMID:8942157

  18. Base Station Walk-Back - Duration: 2 minutes, 10 seconds.

    NASA Video Gallery

    Train to improve your lung, heart, and other muscle endurance while walking a progressive, measured distance. The Train Like an Astronaut project uses the excitement of exploration to challenge stu...

  19. Metabolic and Circulatory Responses to Walking and Jogging in Water.

    ERIC Educational Resources Information Center

    Evans, Blanch W.

    1978-01-01

    Water resistance makes running or walking through waist-deep water more strenuous than when performed under normal conditions; however, the buoyancy of the water reduces the stress on weight-bearing muscles and joints. (MM)

  20. Recurrences in three-state quantum walks on a plane

    SciTech Connect

    Kollar, B.; Kiss, T.; Stefanak, M.; Jex, I.

    2010-07-15

    We analyze the role of dimensionality in the time evolution of discrete-time quantum walks through the example of the three-state walk on a two-dimensional triangular lattice. We show that the three-state Grover walk does not lead to trapping (localization) or recurrence to the origin, in sharp contrast to the Grover walk on the two-dimensional square lattice. We determine the power-law scaling of the probability at the origin with the method of stationary phase. We prove that only a special subclass of coin operators can lead to recurrence, and there are no coins that lead to localization. The propagation for the recurrent subclass of coins is quasi-one dimensional.

  1. Localization in quantum walks on a honeycomb network

    NASA Astrophysics Data System (ADS)

    Lyu, Changyuan; Yu, Luyan; Wu, Shengjun

    2015-11-01

    We systematically study the localization effect in discrete-time quantum walks on a honeycomb network and establish the mathematical framework. We focus on the Grover walk first and rigorously derive the limit form of the walker's state, showing it has a certain probability to be localized at the starting position. The relationship between localization and the initial coin state is concisely represented by a linear map. We also define and calculate the average probability of localization by generating random initial states. Further, coin operators varying with positions are considered and the sufficient condition for localization is discussed. We also similarly analyze another four-state Grover walk. Theoretical predictions are all in accord with numerical simulation results. Finally, our results are compared with previous works to demonstrate the unusual trapping effect of quantum walks on a honeycomb network, as well as the advantages of our method.

  2. Incoherent tunneling effects in a one-dimensional quantum walk

    NASA Astrophysics Data System (ADS)

    Annabestani, Mostafa; Javad Akhtarshenas, Seyed; Abolhassani, Mohamad Reza

    2016-03-01

    In this article we investigate the effects of shifting position decoherence, arising from the incoherent tunneling effect in the experimental realization of the quantum walk, on the one-dimensional discrete time quantum walk. We show that in the regime of this type of noise the quantum behavior of the walker does not vanish, in contrast to the coin decoherence for which the walker undergoes a quantum-to-classical transition even for weak noise. In particular, we show that the quadratic dependence of the variance on the time and also the coin–position entanglement, i.e. two important quantum aspects of the coherent quantum walk, are preserved in the presence of tunneling decoherence. Furthermore, we present an explicit expression for the probability distribution of the decoherent one-dimensional quantum walk in terms of the corresponding coherent probabilities, and show that this type of decoherence smooths the probability distribution.

  3. Interior of second floor walk surrounding atrium space, ornate wood ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior of second floor walk surrounding atrium space, ornate wood rafters in view, view facing northeast - U.S. Naval Base, Pearl Harbor, Navy Yard Dispensary, Intersection of Central Avenue & Seventh Street, Pearl City, Honolulu County, HI

  4. Quantum walks with coins undergoing different quantum noisy channels

    NASA Astrophysics Data System (ADS)

    Hao, Qin; Xue, Peng

    2016-01-01

    Quantum walks have significantly different properties compared to classical random walks, which have potential applications in quantum computation and quantum simulation. We study Hadamard quantum walks with coins undergoing different quantum noisy channels and deduce the analytical expressions of the first two moments of position in the long-time limit. Numerical simulations have been done, the results are compared with the analytical results, and they match extremely well. We show that the variance of the position distributions of the walks grows linearly with time when enough steps are taken and the linear coefficient is affected by the strength of the quantum noisy channels. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174052 and 11474049) and the CAST Innovation Fund, China.

  5. Slowed Walking in Seniors May Signal Alzheimer's Danger

    MedlinePLUS

    ... 156007.html Slowed Walking in Seniors May Signal Alzheimer's Danger Study found higher levels of beta amyloid ... have higher amounts of a protein linked to Alzheimer's in their brains, a small, new study suggests. ...

  6. Random walks and search in time-varying networks.

    PubMed

    Perra, Nicola; Baronchelli, Andrea; Mocanu, Delia; Gonalves, Bruno; Pastor-Satorras, Romualdo; Vespignani, Alessandro

    2012-12-01

    The random walk process underlies the description of a large number of real-world phenomena. Here we provide the study of random walk processes in time-varying networks in the regime of time-scale mixing, i.e., when the network connectivity pattern and the random walk process dynamics are unfolding on the same time scale. We consider a model for time-varying networks created from the activity potential of the nodes and derive solutions of the asymptotic behavior of random walks and the mean first passage time in undirected and directed networks. Our findings show striking differences with respect to the well-known results obtained in quenched and annealed networks, emphasizing the effects of dynamical connectivity patterns in the definition of proper strategies for search, retrieval, and diffusion processes in time-varying networks. PMID:23368274

  7. A scaling law for random walks on networks.

    PubMed

    Perkins, Theodore J; Foxall, Eric; Glass, Leon; Edwards, Roderick

    2014-01-01

    The dynamics of many natural and artificial systems are well described as random walks on a network: the stochastic behaviour of molecules, traffic patterns on the internet, fluctuations in stock prices and so on. The vast literature on random walks provides many tools for computing properties such as steady-state probabilities or expected hitting times. Previously, however, there has been no general theory describing the distribution of possible paths followed by a random walk. Here, we show that for any random walk on a finite network, there are precisely three mutually exclusive possibilities for the form of the path distribution: finite, stretched exponential and power law. The form of the distribution depends only on the structure of the network, while the stepping probabilities control the parameters of the distribution. We use our theory to explain path distributions in domains such as sports, music, nonlinear dynamics and stochastic chemical kinetics. PMID:25311870

  8. A plasmonic nanorod that walks on DNA origami

    NASA Astrophysics Data System (ADS)

    Zhou, Chao; Duan, Xiaoyang; Liu, Na

    2015-08-01

    In nano-optics, a formidable challenge remains in precise transport of a single optical nano-object along a programmed and routed path toward a predefined destination. Molecular motors in living cells that can walk directionally along microtubules have been the inspiration for realizing artificial molecular walkers. Here we demonstrate an active plasmonic system, in which a plasmonic nanorod can execute directional, progressive and reverse nanoscale walking on two or three-dimensional DNA origami. Such a walker comprises an anisotropic gold nanorod as its `body' and discrete DNA strands as its `feet'. Specifically, our walker carries optical information and can in situ optically report its own walking directions and consecutive steps at nanometer accuracy, through dynamic coupling to a plasmonic stator immobilized along its walking track. Our concept will enable a variety of smart nanophotonic platforms for studying dynamic light-matter interaction, which requires controlled motion at the nanoscale well below the optical diffraction limit.

  9. Comparison of two walking frequencies in African American postmenopausal women.

    PubMed

    Keller, Colleen S; Robinson, Beverly; Pickens, Linda

    2004-01-01

    Despite the known benefits of exercise, 60% of African American women are sedentary. The efficacy and dose-response effects of low intensity exercise performed in community settings by overweight sedentary women have not been established. The purpose of this study was to examine the effects of two intensities of walking on level of exercise maintenance and on cardiovascular risk factors in sedentary, obese African American women. A two group, randomized experimental approach was used to test 45-70 year old postmenopausal obese African American women, measuring age, self reported ethnic affiliation, height, weight, socioeconomic status, diet history, menopausal status, exercise volume, dietary restrictions, medication use, and medical conditions precluding participation. Group one walked three days/week; group 2 walked 5 days/week; both groups walked at 65% of their target heart rate reserve. PMID:15067791

  10. Record statistics of financial time series and geometric random walks

    NASA Astrophysics Data System (ADS)

    Sabir, Behlool; Santhanam, M. S.

    2014-09-01

    The study of record statistics of correlated series in physics, such as random walks, is gaining momentum, and several analytical results have been obtained in the past few years. In this work, we study the record statistics of correlated empirical data for which random walk models have relevance. We obtain results for the records statistics of select stock market data and the geometric random walk, primarily through simulations. We show that the distribution of the age of records is a power law with the exponent α lying in the range 1.5≤α≤1.8. Further, the longest record ages follow the Fréchet distribution of extreme value theory. The records statistics of geometric random walk series is in good agreement with that obtained from empirical stock data.

  11. Sleep-Walking a Rarest Side Effect of Zolpidem

    PubMed Central

    Singh, Harmanjit; Thangaraju, Pugazhenthan; Natt, Navreet Kaur

    2015-01-01

    A 46-years-old male, with past history of road traffic accident and with no current/past history of substance abuse and no family history of sleep-walking, took zolpidem 10 mg without any prescription and after few days, the patient's son noticed the patient waking up in the middle of night and walking into their room with a staring expression and some incoherent speech. The patient had no memory of this event in the morning. This sleep-walking episode was attributed to zolpidem, as no medication change was made besides new start of zolpidem and the patient had no history of such episodes in the past. Zolpidem treatment was stopped, and since then, no further complaints of sleep-walking were reported. PMID:25722525

  12. FRACTAL DIMENSION RESULTS FOR CONTINUOUS TIME RANDOM WALKS

    PubMed Central

    Meerschaert, Mark M.; Nane, Erkan; Xiao, Yimin

    2013-01-01

    Continuous time random walks impose random waiting times between particle jumps. This paper computes the fractal dimensions of their process limits, which represent particle traces in anomalous diffusion. PMID:23482421

  13. Kinematic parameters of sheep walking on a treadmill

    PubMed Central

    Valentin, Stephanie; Essigbeck, Annika; Wolfram, Ines; Licka, Theresia

    2014-01-01

    Ovine locomotion studies are rare, despite their relevance for medical research. The aim of this preliminary study was to investigate habituation and temporospatial parameters during treadmill walking of seven Austrian Mountain sheep. Sheep were nave to treadmill exercise. During five treadmill sessions, movement cycle duration (MCD), vertical trunk movement (VTM), stride height (SH), stride length (SL), and percentage of movement cycle at stance (%St) were assessed. Two sheep were excluded from the study because they would not walk on the treadmill. From the end measurement session, MCD (0.95 s) and %St (62%) were similar to reported kinetics of sheep walking over ground, although stride length (1.05 m) was longer in this study. These findings suggest that sheep may require more than five sessions to become habituated to treadmill walking. PMID:25457259

  14. 11. LAUREL POOL, LOOKING NORTHWEST FROM HAZEL WALK Photocopy of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. LAUREL POOL, LOOKING NORTHWEST FROM HAZEL WALK Photocopy of photograph, 1930s National Park Service, National Capital Region files - Dumbarton Oaks Park, Thirty-second & R Streets Northwest, Washington, District of Columbia, DC

  15. 9. CLIFTON HILL, LOOKING NORTHEAST ACROSS STREAM FROM HAZEL WALK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. CLIFTON HILL, LOOKING NORTHEAST ACROSS STREAM FROM HAZEL WALK Photocopy of photograph, 1930s National Park Service, National Capital Region files - Dumbarton Oaks Park, Thirty-second & R Streets Northwest, Washington, District of Columbia, DC

  16. 10. CLIFTON HILL, LOOKING NORTHWEST ACROSS STREAM FROM HAZEL WALK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. CLIFTON HILL, LOOKING NORTHWEST ACROSS STREAM FROM HAZEL WALK Photocopy of photograph, 1930s National Park Service, National Capital Region files - Dumbarton Oaks Park, Thirty-second & R Streets Northwest, Washington, District of Columbia, DC

  17. 61. View forward down hurricane deck toward salon clerestory, walking ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    61. View forward down hurricane deck toward salon clerestory, walking beam, stack, and wheelhouse. Second smaller stack is from donkey boiler on main deck. - Ferry TICONDEROGA, Route 7, Shelburne, Chittenden County, VT

  18. Fractional Brownian Motion:. Theory and Application to DNA Walk

    NASA Astrophysics Data System (ADS)

    Lim, S. C.; Muniandy, S. V.

    2001-09-01

    This paper briefly reviews the theory of fractional Brownian motion (FBM) and its generalization to multifractional Brownian motion (MBM). FBM and MBM are applied to a biological system namely the DNA sequence. By considering a DNA sequence as a fractal random walk, it is possible to model the noncoding sequence of human retinoblastoma DNA as a discrete version of FBM. The average scaling exponent or Hurst exponent of the DNA walk is estimated to be H = 0.60 0.05 using the monofractal R/S analysis. This implies that the mean square fluctuation of DNA walk belongs to anomalous superdiffusion type. We also show that the DNA landscape is not monofractal, instead one has multifractal DNA landscape. The empirical estimates of the Hurst exponent falls approximately within the range H ~ 0.62 - 0.72. We propose two multifractal models, namely the MBM and multiscale FBM to describe the existence of different Hurst exponents in DNA walk.

  19. A scaling law for random walks on networks

    NASA Astrophysics Data System (ADS)

    Perkins, Theodore J.; Foxall, Eric; Glass, Leon; Edwards, Roderick

    2014-10-01

    The dynamics of many natural and artificial systems are well described as random walks on a network: the stochastic behaviour of molecules, traffic patterns on the internet, fluctuations in stock prices and so on. The vast literature on random walks provides many tools for computing properties such as steady-state probabilities or expected hitting times. Previously, however, there has been no general theory describing the distribution of possible paths followed by a random walk. Here, we show that for any random walk on a finite network, there are precisely three mutually exclusive possibilities for the form of the path distribution: finite, stretched exponential and power law. The form of the distribution depends only on the structure of the network, while the stepping probabilities control the parameters of the distribution. We use our theory to explain path distributions in domains such as sports, music, nonlinear dynamics and stochastic chemical kinetics.

  20. VIEW OF BUILDING 22, INTERIOR OF OBSERVATION WALK ABOVE RACQUET ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BUILDING 22, INTERIOR OF OBSERVATION WALK ABOVE RACQUET BALL COURTS, FACING NORTH - Roosevelt Base, Field House, Corner of West Virginia Street & Reeves Avenue, Long Beach, Los Angeles County, CA

  1. Impact Forces of Walking and Running at the Same Intensity.

    PubMed

    Swain, David P; Kelleran, Kyle J; Graves, Melani S; Morrison, Steven

    2016-04-01

    Swain, DP, Kelleran, KJ, Graves, MS, and Morrison, S. Impact forces of walking and running at the same intensity. J Strength Cond Res 30(4): 1042-1049, 2016-Moderate-intensity walking (horizontal, WH), vigorous-intensity walking (incline, WI), and vigorous-intensity running (horizontal, R) were compared. The hypothesis is that running creates greater loading forces than walking even at the same aerobic intensity. Young adults (10 M and 10 F; age, 22.8 ± 0.5 years) performed 3 exercise trials in a counter-balanced order: walking 5.5 kph at 0% grade (WH); walking 5.5 kph at 11% (WI); and running at 8.0 kph at 0% (R). Oxygen consumption (V[Combining Dot Above]O2), step frequency, peak vertical ground reaction force (VGRF), and vertical force loading rate were recorded during the last 5 minutes of each trial. Results are mean ± SE. Net V[Combining Dot Above]O2 during WH (10.5 ± 0.3 ml·min·kg) was significantly less than WI (26.3 ± 0.3) and R (25.1 ± 0.7 ml·min·kg). Step frequency was significantly greater during R (163 ± 1.5 steps per minute) than both walking conditions (WH, 128 ± 1.0 steps per minute; WI, 126 ± 1.2 steps per minute). Peak VGRF was significantly greater during running (844 ± 47 N) than both walking conditions (WH, 581 ± 27 N; WI, 565 ± 28 N). Force loading rate was significantly greater with R (8,214 ± 26 N·s) than WH (6,497 ± 15 N·s ) and WI (5,699 ± 16 N·s ), with WH > WI. Vigorous-intensity walking produced no greater loading forces than moderate-intensity walking. However, running at a vigorous intensity produced substantially greater loading forces than walking of the same intensity. These findings suggest that vigorous aerobic exercise may be performed without elevated orthopedic stress, depending on the mode prescribed. PMID:27003452

  2. Reconstructing the behavior of walking fruit flies

    NASA Astrophysics Data System (ADS)

    Berman, Gordon; Bialek, William; Shaevitz, Joshua

    2010-03-01

    Over the past century, the fruit fly Drosophila melanogaster has arisen as almost a lingua franca in the study of animal behavior, having been utilized to study questions in fields as diverse as sleep deprivation, aging, and drug abuse, amongst many others. Accordingly, much is known about what can be done to manipulate these organisms genetically, behaviorally, and physiologically. Most of the behavioral work on this system to this point has been experiments where the flies in question have been given a choice between some discrete set of pre-defined behaviors. Our aim, however, is simply to spend some time with a cadre of flies, using techniques from nonlinear dynamics, statistical physics, and machine learning in an attempt to reconstruct and gain understanding into their behavior. More specifically, we use a multi-camera set-up combined with a motion tracking stage in order to obtain long time-series of walking fruit flies moving about a glass plate. This experimental system serves as a test-bed for analytical, statistical, and computational techniques for studying animal behavior. In particular, we attempt to reconstruct the natural modes of behavior for a fruit fly through a data-driven approach in a manner inspired by recent work in C. elegans and cockroaches.

  3. Discovering walking technirho mesons at the LHC

    NASA Astrophysics Data System (ADS)

    Kurachi, Masafumi; Matsuzaki, Shinya; Yamawaki, Koichi

    2014-09-01

    We formulate a scale-invariant hidden local symmetry (HLS) as a low-energy effective theory of walking technicolor (WTC) which includes the technidilaton, technipions, and technirho mesons as the low-lying spectra. As a benchmark for LHC phenomenology, we in particular focus on the one-family model of WTC having eight technifermion flavors, which can beat energy scales relevant to the reach of the LHCdescribed by the scale-invariant HLS based on the manifold [SU(8)LSU(8)R]globalSU(8)local/SU(8)V, where SU(8)local is the HLS and the global SU(8)LSU(8)R symmetry is partially gauged by the SU(3)SU(2)LU(1)Y of the standard model. Based on the scale-invariant HLS, we evaluate the coupling properties of the technirho mesons and place limits on the masses from the current LHC data. Then, implications for future LHC phenomenology are discussed by focusing on the technirho mesons produced through the Drell-Yan process. We find that the color-octet technirho decaying to the technidilaton along with the gluon is of interest as the discovery channel at the LHC, which would provide a characteristic signature to probe the one-family WTC.

  4. ISWI Remodels Nucleosomes through a Random Walk

    PubMed Central

    2015-01-01

    The chromatin remodeler ISWI is capable of repositioning clusters of nucleosomes to create well-ordered arrays or moving single nucleosomes from the center of DNA fragments toward the ends without disrupting their integrity. Using standard electrophoresis assays, we have monitored the ISWI-catalyzed repositioning of different nucleosome samples each containing a different length of DNA symmetrically flanking the initially centrally positioned histone octamer. We find that ISWI moves the histone octamer between distinct and thermodynamically stable positions on the DNA according to a random walk mechanism. Through the application of a spectrophotometric assay for nucleosome repositioning, we further characterized the repositioning activity of ISWI using short nucleosome substrates and were able to determine the macroscopic rate of nucleosome repositioning by ISWI. Additionally, quantitative analysis of repositioning experiments performed at various ISWI concentrations revealed that a monomeric ISWI is sufficient to obtain the observed repositioning activity as the presence of a second ISWI bound had no effect on the rate of nucleosome repositioning. We also found that ATP hydrolysis is poorly coupled to nucleosome repositioning, suggesting that DNA translocation by ISWI is not energetically rate-limiting for the repositioning reaction. This is the first calculation of a microscopic ATPase coupling efficiency for nucleosome repositioning and also further supports our conclusion that a second bound ISWI does not contribute to the repositioning reaction. PMID:24898619

  5. Walking capabilities of Gregor controlled through Walknet

    NASA Astrophysics Data System (ADS)

    Arena, Paolo; Patané, Luca; Schilling, Malte; Schmitz, Josef

    2007-05-01

    Locomotion control of legged robots is nowadays a field in continuous evolution. In this work a bio-inspired control architecture based on the stick insect is applied to control the hexapod robot Gregor. The control scheme is an extension of Walknet, a decentralized network inspired by the stick insect, that on the basis of local reflexes generates the control signals needed to coordinate locomotion in hexapod robots. Walknet has been adapted to the specific mechanical structure of Gregor that is characterized by specialized legs and a sprawled posture. In particular an innovative hind leg geometry, inspired by the cockroach, has been considered to improve climbing capabilities. The performances of the new control architecture have been evaluated in dynamic simulation environments. The robot has been endowed with distance and contact sensors for obstacle detection. A heading control is used to avoid large obstacles, and an avoidance reflex, as can be found in stick insects, has been introduced to further improve climbing capabilities of the structure. The reported results, obtained in different environmental configurations, stress the adaptive capabilities of the Walknet approach: Even in unpredictable and cluttered environments the walking behaviour of the simulated robot and the robot prototype, controlled through a FPGA based board, remained stable.

  6. Random walks in directed modular networks

    NASA Astrophysics Data System (ADS)

    Comin, Cesar H.; Viana, Mateus P.; Antiqueira, Lucas; Costa, Luciano da F.

    2014-12-01

    Because diffusion typically involves symmetric interactions, scant attention has been focused on studying asymmetric cases. However, important networked systems underlain by diffusion (e.g. cortical networks and WWW) are inherently directed. In the case of undirected diffusion, it can be shown that the steady-state probability of the random walk dynamics is fully correlated with the degree, which no longer holds for directed networks. We investigate the relationship between such probability and the inward node degree, which we call efficiency, in modular networks. Our findings show that the efficiency of a given community depends mostly on the balance between its ingoing and outgoing connections. In addition, we derive analytical expressions to show that the internal degree of the nodes does not play a crucial role in their efficiency, when considering the Erdős-Rényi and Barabási-Albert models. The results are illustrated with respect to the macaque cortical network, providing subsidies for improving transportation and communication systems.

  7. The role of series ankle elasticity in bipedal walking.

    PubMed

    Zelik, Karl E; Huang, Tzu-Wei P; Adamczyk, Peter G; Kuo, Arthur D

    2014-04-01

    The elastic stretch-shortening cycle of the Achilles tendon during walking can reduce the active work demands on the plantarflexor muscles in series. However, this does not explain why or when this ankle work, whether by muscle or tendon, needs to be performed during gait. We therefore employ a simple bipedal walking model to investigate how ankle work and series elasticity impact economical locomotion. Our model shows that ankle elasticity can use passive dynamics to aid push-off late in single support, redirecting the body's center-of-mass (COM) motion upward. An appropriately timed, elastic push-off helps to reduce dissipative collision losses at contralateral heelstrike, and therefore the positive work needed to offset those losses and power steady walking. Thus, the model demonstrates how elastic ankle work can reduce the total energetic demands of walking, including work required from more proximal knee and hip muscles. We found that the key requirement for using ankle elasticity to achieve economical gait is the proper ratio of ankle stiffness to foot length. Optimal combination of these parameters ensures proper timing of elastic energy release prior to contralateral heelstrike, and sufficient energy storage to redirect the COM velocity. In fact, there exist parameter combinations that theoretically yield collision-free walking, thus requiring zero active work, albeit with relatively high ankle torques. Ankle elasticity also allows the hip to power economical walking by contributing indirectly to push-off. Whether walking is powered by the ankle or hip, ankle elasticity may aid walking economy by reducing collision losses. PMID:24365635

  8. The melting phenomenon in random-walk model of DNA

    SciTech Connect

    Hayrapetyan, G. N.; Mamasakhlisov, E. Sh.; Papoyan, Vl. V.; Poghosyan, S. S.

    2012-10-15

    The melting phenomenon in a double-stranded homopolypeptide is considered. The relative distance between the corresponding monomers of two polymer chains is modeled by the two-dimensional random walk on the square lattice. Returns of the random walk to the origin describe the formation of hydrogen bonds between complementary units. To take into account the two competing interactions of monomers inside the chains, we obtain a completely denatured state at finite temperature T{sub c}.

  9. Straight walking and turning on a slippery surface.

    PubMed

    Gruhn, Matthias; Zehl, Lyuba; Bschges, Ansgar

    2009-01-01

    In stick insects, walking is the result of the co-action of different pattern generators for the single legs and coordinating inter-leg influences. We have used a slippery surface setup to understand the role the local neuronal processing in the thoracic ganglia plays in the ability of the animal to show turning movements. To achieve this, we removed the influence of mechanical coupling through the ground by using the slippery surface and removed sensory input by the successive amputation of neighboring legs. We analyzed the walking pattern of the front, middle and hind legs of tethered animals mounted above the surface and compared the kinematics of the straight walking legs with those of the curve walking inside and outside legs. The walking pattern was monitored both electrically through tarsal contact measurement and optically by using synchronized high-speed video. The vectors of leg movement are presented for the intact and a reduced preparation. Animals showed the ability to walk in a coordinated fashion on the slippery surface. Upon change from straight to curve walking, the stride length for the inside legs shortens and the vector of movement of the inner legs changes to pull the animal into the curve, while the outer legs act to pull and push it into the turn. In the reduced two-leg and in the single-leg preparation the behavior of the legs remained largely unchanged in the behavioral contexts of straight walking or turning with only small changes in the extreme positions. This suggests that the single stepping legs perform given motor programs on the slippery surface in a fashion that is highly independent not only of mechanical coupling between but also of the presence of the other legs. PMID:19112138

  10. Ising model observables and non-backtracking walks

    SciTech Connect

    Helmuth, Tyler

    2014-08-15

    This paper presents an alternative proof of the connection between the partition function of the Ising model on a finite graph G and the set of non-backtracking walks on G. The techniques used also give formulas for spin-spin correlation functions in terms of non-backtracking walks. The main tools used are Viennot's theory of heaps of pieces and turning numbers on surfaces.

  11. Ontogeny of bipedal locomotion: walking and running in the chick.

    PubMed Central

    Muir, G D; Gosline, J M; Steeves, J D

    1996-01-01

    1. The purpose of this study was to determine whether the production of an energy-efficient bipedal walk is an innate attribute of a precocial bird. 2. The locomotor characteristics of hatchling chicks were quantified using kinetic (ground reaction forces) and kinematic (stride length, leg support duration) measurements as the animals moved overground unrestrained. All measurements were made over a range of velocities and at regular intervals throughout the first 2 weeks of life. 3. Ground reaction force records showed that, like all terrestrial walking vertebrates, chicks undergo cyclical increases and decreases in the body's potential and kinetic energy with each step. The out-of-phase exchange of potential with kinetic energy is an efficient mechanism for the conservation of energy during walking. However, comparisons between chicks at posthatching (P) days 1-2 and P14 revealed that P1-2 chicks are unable to conserve energy because they walk with disproportionately small potential energy oscillations. During running, however, the oscillations between potential and kinetic energy are similar for both P1-2 and P14 animals. 4. P1-2 chicks also walk with a shorter stride length than P14 chicks. Examination of limb support durations shows that younger animals (P1-2, P3) spend less time in single limb support than P14 animals during walking but not running. 5. The results show that even highly precocial bipeds need to acquire the ability to walk in a controlled and energy efficient manner, although they can innately run as well as an adult. This disparity could be due to the distinct actions of the legs in these two behaviours, and the requirement for longer durations of single leg support during walking. These differences relate to constraints inherent to bipedal locomotion and many of the locomotor changes occurring in the first weeks after hatching may therefore be analogous to similar changes seen during human locomotor development. PMID:8782119

  12. Constrained optimization in human walking: cost minimization and gait plasticity.

    PubMed

    Bertram, John E A

    2005-03-01

    As walking speed increases, consistent relationships emerge between the three determinant parameters of walking, speed, step frequency and step length. However, when step length or step frequency are predetermined rather than speed, different relationships are spontaneously selected. This result is expected if walking parameters are selected to optimize to an underlying objective function, known as the constrained optimization hypothesis. The most likely candidate for the objective function is metabolic cost per distance traveled, where the hypothesis predicts that the subject will minimize the cost of travel under a given gait constraint even if this requires an unusual step length and frequency combination. In the current study this is tested directly by measuring the walking behavior of subjects constrained systematically to determined speeds, step frequencies or step lengths and comparing behavior to predictions derived directly from minimization of measured metabolic cost. A metabolic cost surface in speed-frequency space is derived from metabolic rate for 10 subjects walking at 49 speed-frequency conditions. Optimization is predicted from the iso-energetic cost contours derived from this surface. Substantial congruence is found between the predicted and observed behavior using the cost of walking per unit distance. Although minimization of cost per distance appears to dominate walking control, certain notable differences from predicted behavior suggest that other factors must also be considered. The results of these studies provide a new perspective on the integration of walking cost with neuromuscular control, and provide a novel approach to the investigation of the control features involved in gait parameter selection. PMID:15767300

  13. Toe walking as a presenting sign of systemic lupus erythematosus.

    PubMed

    Basiaga, M; Sherry, D

    2015-10-01

    Toe walking is a previously unreported presentation of systemic lupus erythematosus (SLE). We describe a patient who presented with profound multisystem involvement that was preceded by one month of toe walking and multiple flexion contractures without arthritis. Her lupus is now under control after aggressive therapy, yet she continues to struggle with tendinopathy despite continued physical and occupational therapy. Lupus should be considered in the appropriate clinical context in children who have new-onset contractures due to tight tendons. PMID:25972365

  14. Walking with increased ankle pushoff decreases hip muscle moments.

    PubMed

    Lewis, Cara L; Ferris, Daniel P

    2008-07-19

    In a simple bipedal walking model, an impulsive push along the trailing limb (similar to ankle plantar flexion) or a torque at the hip can power level walking. This suggests a tradeoff between ankle and hip muscle requirements during human gait. People with anterior hip pain may benefit from walking with increased ankle pushoff if it reduces hip muscle forces. The purpose of our study was to determine if simple instructions to alter ankle pushoff can modify gait dynamics and if resulting changes in ankle pushoff have an effect on hip muscle requirements during gait. We hypothesized that changes in ankle kinetics would be inversely related to hip muscle kinetics. Ten healthy subjects walked on a custom split-belt force-measuring treadmill at 1.25m/s. We recorded ground reaction forces and lower extremity kinematic data to calculate joint angles and internal muscle moments, powers and angular impulses. Subjects walked under three conditions: natural pushoff, decreased pushoff and increased pushoff. For the decreased pushoff condition, subjects were instructed to push less with their feet as they walked. Conversely, for the increased pushoff condition, subjects were instructed to push more with their feet. As predicted, walking with increased ankle pushoff resulted in lower peak hip flexion moment, power and angular impulse as well as lower peak hip extension moment and angular impulse (p<0.05). Our results emphasize the interchange between hip and ankle kinetics in human walking and suggest that increased ankle pushoff during gait may help to compensate for hip muscle weakness or injury and reduce hip joint forces. PMID:18606419

  15. Changes in walking and running in patients with hip dysplasia

    PubMed Central

    2013-01-01

    Background and purpose Earlier studies have suggested that the hip extension angle and the hip flexor moment in walking are affected by hip dysplasia, but to our knowledge there have been no reports on running or evaluations of self-reported health. We evaluated differences in walking, running, and self-reported health between young adults with symptomatic hip dysplasia and healthy controls. Patients and methods Walking and running in 32 patients with hip dysplasia, mean 34 (18–53) years old, was compared with walking and running in 32 controls, mean 33 (18–54) years old. Joint kinematics and kinetics—quantified by the peak hip extension angle and the peak net joint moment of hip flexion during walking and running—were recorded using a motion-capture system, and health was evaluated using the Copenhagen Hip and Groin Outcome Score (HAGOS). Results The peak hip extension angle during walking was less in the patients than in the controls (–10.4 (SD 4.8) degrees vs. –13.2 (SD 4.5) degrees; p = 0.02). Similarly, the peak net joint moment of hip flexion during walking was lower in the patients than in the controls (0.57 (SD 0.13) N*m/kg vs. 0.70 (SD 0.22) N*m/kg; p = 0.008). In all dimensions of HAGOS, the patients scored lower than the controls. Furthermore, the hip extension angle and the net joint moment of hip flexion correlated with the HAGOS subscales pain and physical function in sport and recreation. Interpretation Patients with symptomatic hip dysplasia do modify walking and running, and we therefore suggest that the impairment found in this study should play an important role in the evaluation of later operative and training interventions. PMID:23594221

  16. Ising model observables and non-backtracking walks

    NASA Astrophysics Data System (ADS)

    Helmuth, Tyler

    2014-08-01

    This paper presents an alternative proof of the connection between the partition function of the Ising model on a finite graph G and the set of non-backtracking walks on G. The techniques used also give formulas for spin-spin correlation functions in terms of non-backtracking walks. The main tools used are Viennot's theory of heaps of pieces and turning numbers on surfaces.

  17. One-Dimensional Quantum Walks with One Defect

    NASA Astrophysics Data System (ADS)

    Cantero, M. J.; Grünbaum, F. A.; Moral, L.; Velázquez, L.

    The CGMV method allows for the general discussion of localization properties for the states of a one-dimensional quantum walk, both in the case of the integers and in the case of the nonnegative integers. Using this method we classify, according to such localization properties, all the quantum walks with one defect at the origin, providing explicit expressions for the asymptotic return probabilities to the origin.

  18. Stance and swing phase costs in human walking

    PubMed Central

    Umberger, Brian R.

    2010-01-01

    Leg swing in human walking has historically been viewed as a passive motion with little metabolic cost. Recent estimates of leg swing costs are equivocal, covering a range from 10 to 33 per cent of the net cost of walking. There has also been a debate as to whether the periods of double-limb support during the stance phase dominate the cost of walking. Part of this uncertainty is because of our inability to measure metabolic energy consumption in individual muscles during locomotion. Therefore, the purpose of this study was to investigate the metabolic cost of walking using a modelling approach that allowed instantaneous energy consumption rates in individual muscles to be estimated over the full gait cycle. At a typical walking speed and stride rate, leg swing represented 29 per cent of the total muscular cost. During the stance phase, the double-limb and single-limb support periods accounted for 27 and 44 per cent of the total cost, respectively. Performing step-to-step transitions, which encompasses more than just the double-support periods, represented 37 per cent of the total cost of walking. Increasing stride rate at a constant speed led to greater double-limb support costs, lower swing phase costs and no change in single-limb support costs. Together, these results provide unique insight as to how metabolic energy is expended over the human gait cycle. PMID:20356877

  19. Transforming walk-away VSP data into reverse VSP data

    SciTech Connect

    Mittet, R.; Hokstad, K.

    1995-07-01

    Marine walk-away vertical seismic profiling (VSP) data can be transformed into reverse VSP data using an elastic reciprocity transformation. A reciprocity transform is derived and tested using data generated with a 2-D high-order, finite-difference modeling scheme in a complex elastic model. First, 201 shots are generated with a walk-away VSP experimental configuration. Both the x-component and the z-component of the displacement are measured. These data are collected in two common receiver data sets. Then two shots are generated in a reverse VSP configuration. The authors demonstrate that subtraction of the reverse VSP data from the walk-away VSP data gives very small residuals. The transformation of walk-away data into reverse VSP data makes prestack shot-domain migration feasible for walk-away data. Synthetic data from a multishot walk-away experiment can abe obtained from one or a few modeling operations with a RVSP experimental configuration. The required computer time is reduced by two orders of magnitude.

  20. Introduction of New Motion Measurement Equipment into Virtual Walk System

    NASA Astrophysics Data System (ADS)

    Furukawa, Tatsuya; Itoh, Hideaki; Hori, Toshiyuki; Fukumoto, Hisao; Wakuya, Hiroshi; Ohchi, Masashi

    The Virtual Walk System has been developed to support rehabilitation therapy in homes. In the system, a user has been able to perform walking-like exercise on a fitness machine called a stepper. In front of the user, a projected image of a vast virtual reality space is generated by 3-dimensional computer graphics (3DCG). The user's movement is measured and the projected image changes just like the user is walking in the virtual space. Viewing the changing image, the user can enjoy the exercise. In this study, we have decomposed the virtual walk system into two modules (the measurement and control module operated by a microcomputer board and the 3DCG module operated by a personal computer) to facilitate rapid development. Then we have introduced two kinds of new equipment, i.e., a bicycle for cycling exercise and a treadmill for walking exercise. We have also developed a treadmill control system by which a user can easily change the walking speed during exercise.

  1. Energetics and passive dynamics of the ankle in downhill walking.

    PubMed

    Holm, Jonathan K; Contakos, Jonas; Lee, Sang-Wook; Jang, John

    2010-11-01

    This study investigated the energetics of the human ankle during the stance phase of downhill walking with the goal of modeling ankle behavior with a passive spring and damper mechanism. Kinematic and kinetic data were collected on eight male participants while walking down a ramp with inclination varying from 0 to 8. The ankle joint moment in the sagittal plane was calculated using inverse dynamics. Mechanical energy injected or dissipated at the ankle joint was computed by integrating the power across the duration of the stance phase. The net mechanical energy of the ankle was approximately zero for level walking and monotonically decreased (i.e., became increasingly negative) during downhill walking as the slope decreased. The indication is that the behavior of the ankle is energetically passive during downhill walking, playing a key role in dissipating energy from one step to the next. A passive mechanical model consisting of a pin joint coupled with a revolute spring and damper was fit to the ankle torque and its parameters were estimated for each downhill slope using linear regression. The passive model demonstrated good agreement with actual ankle dynamics as indicated by low root-mean-square error values. These results indicate the stance phase behavior of the human ankle during downhill walking may be effectively duplicated by a passive mechanism with appropriately selected spring and damping characteristics. PMID:21245497

  2. The Fixed Irreducible Bridge Ensemble for Self-Avoiding Walks

    NASA Astrophysics Data System (ADS)

    Gilbert, Michael James

    2015-04-01

    We define a new ensemble for self-avoiding walks in the upper half-plane, the fixed irredicible bridge ensemble, by considering self-avoiding walks in the upper half-plane up to their -th bridge height, , and scaling the walk by to obtain a curve in the unit strip, and then taking . We then conjecture a relationship between this ensemble to in the unit strip from 0 to a fixed point along the upper boundary of the strip, integrated over the conjectured exit density of self-avoiding walk spanning a strip in the scaling limit. We conjecture that there exists a positive constant such that converges in distribution to that of a stable random variable as . Then the conjectured relationship between the fixed irreducible bridge scaling limit and can be described as follows: If one takes a SAW considered up to and scales by and then weights the walk by to an appropriate power, then in the limit , one should obtain a curve from the scaling limit of the self-avoiding walk spanning the unit strip. In addition to a heuristic derivation, we provide numerical evidence to support the conjecture and give estimates for the boundary scaling exponent.

  3. Integration of Human Walking Gyroscopic Data Using Empirical Mode Decomposition

    PubMed Central

    Bonnet, Vincent; Ramdani, Sofiane; Azevedo-Coste, Christine; Fraisse, Philippe; Mazz, Claudia; Cappozzo, Aurelio

    2014-01-01

    The present study was aimed at evaluating the Empirical Mode Decomposition (EMD) method to estimate the 3D orientation of the lower trunk during walking using the angular velocity signals generated by a wearable inertial measurement unit (IMU) and notably flawed by drift. The IMU was mounted on the lower trunk (L4-L5) with its active axes aligned with the relevant anatomical axes. The proposed method performs an offline analysis, but has the advantage of not requiring any parameter tuning. The method was validated in two groups of 15 subjects, one during overground walking, with 180 turns, and the other during treadmill walking, both for steady-state and transient speeds, using stereophotogrammetric data. Comparative analysis of the results showed that the IMU/EMD method is able to successfully detrend the integrated angular velocities and estimate lateral bending, flexion-extension as well as axial rotations of the lower trunk during walking with RMS errors of 1 deg for straight walking and lower than 2.5 deg for walking with turns. PMID:24379044

  4. Neural decoding of treadmill walking from noninvasive electroencephalographic signals

    PubMed Central

    Presacco, Alessandro; Goodman, Ronald; Forrester, Larry

    2011-01-01

    Chronic recordings from ensembles of cortical neurons in primary motor and somatosensory areas in rhesus macaques provide accurate information about bipedal locomotion (Fitzsimmons NA, Lebedev MA, Peikon ID, Nicolelis MA. Front Integr Neurosci 3: 3, 2009). Here we show that the linear and angular kinematics of the ankle, knee, and hip joints during both normal and precision (attentive) human treadmill walking can be inferred from noninvasive scalp electroencephalography (EEG) with decoding accuracies comparable to those from neural decoders based on multiple single-unit activities (SUAs) recorded in nonhuman primates. Six healthy adults were recorded. Participants were asked to walk on a treadmill at their self-selected comfortable speed while receiving visual feedback of their lower limbs (i.e., precision walking), to repeatedly avoid stepping on a strip drawn on the treadmill belt. Angular and linear kinematics of the left and right hip, knee, and ankle joints and EEG were recorded, and neural decoders were designed and optimized with cross-validation procedures. Of note, the optimal set of electrodes of these decoders were also used to accurately infer gait trajectories in a normal walking task that did not require subjects to control and monitor their foot placement. Our results indicate a high involvement of a fronto-posterior cortical network in the control of both precision and normal walking and suggest that EEG signals can be used to study in real time the cortical dynamics of walking and to develop brain-machine interfaces aimed at restoring human gait function. PMID:21768121

  5. Current-reinforced random walks for constructing transport networks.

    PubMed

    Ma, Qi; Johansson, Anders; Tero, Atsushi; Nakagaki, Toshiyuki; Sumpter, David J T

    2013-03-01

    Biological systems that build transport networks, such as trail-laying ants and the slime mould Physarum, can be described in terms of reinforced random walks. In a reinforced random walk, the route taken by 'walking' particles depends on the previous routes of other particles. Here, we present a novel form of random walk in which the flow of particles provides this reinforcement. Starting from an analogy between electrical networks and random walks, we show how to include current reinforcement. We demonstrate that current-reinforcement results in particles converging on the optimal solution of shortest path transport problems, and avoids the self-reinforcing loops seen in standard density-based reinforcement models. We further develop a variant of the model that is biologically realistic, in the sense that the particles can be identified as ants and their measured density corresponds to those observed in maze-solving experiments on Argentine ants. For network formation, we identify the importance of nonlinear current reinforcement in producing networks that optimize both network maintenance and travel times. Other than ant trail formation, these random walks are also closely related to other biological systems, such as blood vessels and neuronal networks, which involve the transport of materials or information. We argue that current reinforcement is likely to be a common mechanism in a range of systems where network construction is observed. PMID:23269849

  6. Self-avoiding walks on scale-free networks

    NASA Astrophysics Data System (ADS)

    Herrero, Carlos P.

    2005-01-01

    Several kinds of walks on complex networks are currently used to analyze search and navigation in different systems. Many analytical and computational results are known for random walks on such networks. Self-avoiding walks (SAW’s) are expected to be more suitable than unrestricted random walks to explore various kinds of real-life networks. Here we study long-range properties of random SAW’s on scale-free networks, characterized by a degree distribution P (k) ˜ k-γ . In the limit of large networks (system size N→∞ ), the average number sn of SAW’s starting from a generic site increases as μn , with μ= < k2 > / -1 . For finite N , sn is reduced due to the presence of loops in the network, which causes the emergence of attrition of the paths. For kinetic growth walks, the average maximum length increases as a power of the system size: ˜ Nα , with an exponent α increasing as the parameter γ is raised. We discuss the dependence of α on the minimum allowed degree in the network. A similar power-law dependence is found for the mean self-intersection length of nonreversal random walks. Simulation results support our approximate analytical calculations.

  7. 75 FR 17080 - Energy Conservation Standards for Walk-in Coolers and Walk-in Freezers: Public Meeting and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-05

    ...The U.S. Department of Energy (DOE) will hold a public meeting to discuss and receive comments on: The equipment classes that DOE plans to analyze for establishing energy conservation standards for walk-in coolers and walk-in freezers; the analytical framework, models, and tools that DOE is using to evaluate standards for this equipment; the results of preliminary analyses performed by DOE for......

  8. Observing a Movement Correction during Walking Affects Evoked Responses but Not Unperturbed Walking

    PubMed Central

    Behrendt, Frank; de Lussanet, Marc H. E.; Wagner, Heiko

    2014-01-01

    Seeing an action activates neurons in the premotor, motor, and somatosensory cortex. Since a significant fraction of these pyramidal neurons project to the spinal motor circuits, a central question is why we do not automatically perform the actions that we see. Indeed, seeing an action increases both cortical and spinal excitability of consistent motor patterns that correspond to the observed ones. Thus, it is believed that such imitative motor patterns are either suppressed or remain at a sub-threshold level. This would predict, however, that seeing someone make a corrective movement while one is actively involved in the same action should either suppress evoked responses or suppress or modulate the action itself. Here we tested this prediction, and found that seeing someone occasionally stepping over an obstacle while walking on a treadmill did not affect the normal walking pattern at all. However, cutaneously evoked reflexes in the anterior tibial and soleus muscles were modulated as if the subject was stepping over an obstacle. This result thus indicates that spinal activation was not suppressed and was neither at sub-threshold motor resonance. Rather, the spinal modulation from observed stepping reflects an adaptive mechanism for regulating predictive control mechanisms. We conclude that spinal excitability during action observation is not an adverse side-effect of action understanding but reflects adaptive and predictive motor control. PMID:25133714

  9. Motivated to walk but nowhere to walk to: Differential effect of a mass media campaign by mix of local destinations

    PubMed Central

    Barnes, Rosanne; Bauman, Adrian E.; Giles-Corti, Billie; Knuiman, Matthew W.; Rosenberg, Michael; Leyden, Kevin M.; Abildso, Christiaan G.; Reger-Nash, Bill

    2015-01-01

    Objective Built environment attributes are associated with walking but little is known about how the impact of walking campaigns varies across different environments. The objective of this study was to compare the impact of a campaign on changes in walking between respondents with a high versus low mix of local destinations. Methods Pre- and post-campaign data from a quasi-experimental study were used to compare changes in walking for residents aged 4065 with high and low destination mix in a West Virginia community campaign (MarchMay 2005). Results Overall samples consisted of 777 intervention community respondents and 388 comparison community respondents with pre- and post-campaign data. Among insufficiently active intervention respondents, those with high destination mix increased their walking by 0.64days more than those with low mix (p<0.05). No significant differences were observed among the comparison community. Conclusion The walking response to campaigns in those insufficiently active may be influenced by neighborhood attributes. PMID:26844097

  10. Liberating Lvy walk research from the shackles of optimal foraging.

    PubMed

    Reynolds, Andy

    2015-09-01

    There is now compelling evidence that many organisms have movement patterns that can be described as Lvy walks, or Lvy flights. Lvy movement patterns have been identified in cells, microorganisms, molluscs, insects, reptiles, fish, birds and even human hunter-gatherers. Most research into Lvy walks as models of organism movement patterns has been shaped by the 'Lvy flight foraging hypothesis'. This states that, since Lvy walks can optimize search efficiencies, natural selection should lead to adaptations that select ?for Lvy walk foraging. However, a growing body of research on generative mechanisms suggests that Lvy walks can arise freely as by-products of otherwise innocuous behaviours; consequently their advantageous properties are purely coincidental. This suggests that the Lvy flight foraging hypothesis should be amended, or even replaced, by a simpler and more general hypothesis. This new hypothesis would state that 'Lvy walks emerge spontaneously and naturally from innate behaviours and innocuous responses to the environment but, if advantageous, then there could be selection against losing them'. The new hypothesis has the virtue of making fewer assumptions and being broader than the original hypothesis; it also encompasses the many examples of suboptimal Lvy patterns that challenge the prevailing paradigm. This does not detract from the Lvy flight foraging hypothesis, in fact, it adds to the theory by providing a stronger and more compelling case for the occurrence of Lvy walks. It dispenses with concerns about the theoretical arguments in support of the Lvy flight foraging hypothesis and so may lead to a wider acceptance of Lvy walks as models of movement pattern data. Furthermore, organisms can approximate Lvy walks by adapting intrinsic behaviour in simple ways; this occurs when Lvy movement patterns are advantageous, but come with an associated cost. These new developments represent a major change in perspective and provide the broadest picture yet of Lvy movement patterns. However, the process of understanding and identifying Lvy movement patterns still has a long way to go, and further reinterpretations and shifts in understanding will occur. In conclusion, Lvy walk research remains exciting precisely because so much remains to be understood, and because, even relatively small studies, are interesting discoveries in their own right. PMID:25835600

  11. Random walks of internal visual states.

    PubMed

    Wexler, Mark; Mamassian, Pascal

    2015-09-01

    We have previously (Wexler & Mamassian, VSS 2014) reported that there exist two independent biases related to the perception of 3D shape and motion from optic flow. These biases are both robust within observers, and highly variable across observers. Here we present a quantitative analysis of time series of these two variables, sampled once a day over three months in 97 observers. The temporal power spectra and autocorrelation structure of these time series show that they do not consist of independent samples from fixed distributions ("white noise"), but rather depend on internal variables that undergo cumulative changes over time. This observation is amplified by an analysis in the Box-Jenkins ARIMA framework, which shows that in most observers the time series are well modeled as random walks (or "Brownian motion") with superimposed measurement noise. Thus, we have evidence that the perception of at least two families of visual stimuli is governed by internal variables. Further, we show that (1) these variables can change both in response to external stimuli and perturbations, as well as during periods of complete darkness, showing that at least some of their dynamics is internal in origin; (2) the biases are strong enough to withstand a fair amount of counter-evidence from other depth cues; (3) the variables may not be single-valued but are actually vector fields over the visual field, with non-trivial spatial and temporal structure; (4) there are at least two more independent internal variables for 2D motion, corresponding to steps of 1D gratings and the motion quartet. The dynamic behavior of these variables opens a window on the internal dynamics of the visual system. Meeting abstract presented at VSS 2015. PMID:26326991

  12. Individual characteristics of human walking mechanics.

    PubMed

    Bianchi, L; Angelini, D; Lacquaniti, F

    1998-08-01

    Twenty-four subjects walked at different speeds (V) from 0.4 to 2.6 m s-1, while motion and ground reaction forces were recorded in 3-D space. The total mechanical energy of each body segment was computed as the sum of the gravitational potential, translation and rotation kinetic energies. Energy profiles reveal that there are inter-individual differences, particularly at moderate and fast V. In some subjects, the energy excursions are less pronounced, and tend to evolve out of phase at the lower limbs and trunk. As a consequence, there is a better transfer of energy between the trunk and the leg segments, resulting in smaller oscillations of the net energy of the whole body. There is a threefold variation of the rate of increment of lnPu (the mass-specific mean absolute power) with lnV across subjects. We show that this variability cannot be simply explained on the basis of the different biomechanical characteristics of the subjects, but that it depends on the different kinematic strategies. Subjects differ in their ability to minimize energy oscillations of their body segments and to transfer mechanical energy between the trunk and the limbs. Individual characteristics of the mechanical energy expenditure were correlated with the corresponding kinematic characteristics. The changes of the elevation angles of the lower limb segments covary along a plane in all subjects. Plane orientation (quantified by the direction cosine of the normal with the thigh axis, u3t) at any V is not the same in all subjects, but correlates with the net power output: smaller values of u3t tend to be associated with smaller values of Pu, and vice versa. PMID:9644215

  13. 10 CFR 431.304 - Uniform test method for the measurement of energy consumption of walk-in coolers and walk-in...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... consumption of walk-in coolers and walk-in freezers. 431.304 Section 431.304 Energy DEPARTMENT OF ENERGY... measuring, pursuant to EPCA, the energy consumption of refrigerated bottled or canned beverage vending... (incorporated by reference; see § 431.303). (10) Determine the annual energy consumption of walk-in cooler...

  14. 10 CFR 431.304 - Uniform test method for the measurement of energy consumption of walk-in coolers and walk-in...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... consumption of walk-in coolers and walk-in freezers. 431.304 Section 431.304 Energy DEPARTMENT OF ENERGY... measuring, pursuant to EPCA, the energy consumption of refrigerated bottled or canned beverage vending... (incorporated by reference; see § 431.303). (10) Determine the annual energy consumption of walk-in cooler...

  15. Roll-over characteristics of human walking on inclined surfaces.

    PubMed

    Hansen, Andrew H; Childress, Dudley S; Miff, Steve C

    2004-12-01

    Roll-over characteristics of able-bodied human subjects walking on ramped surfaces were examined in this study. Ten subjects walked at their normal self-selected speed on a level surface, a 5-deg ramp, and a 10-deg ramped surface. Ramps were designed such that ground reaction forces and center of pressure of the ground reaction forces could be measured on their surfaces. This set-up facilitated calculation of the effective rockers that the ankle-foot (AF) and knee-ankle-foot (KAF) systems conformed to during single-limb stance (contralateral toe off to contralateral heel contact). Since our original "roll-over shapes" were characterized between heel contact and opposite heel contact, we label the shapes found during single-limb stance as "truncated roll-over shapes". We hypothesized that the ankle-foot system would adapt to the various surfaces, creating a roll-over shape that would change in orientation with different levels of inclination. The truncated AF roll-over shapes supported this hypothesis for uphill walking but did not support the hypothesis for downhill walking. However, truncated roll-over shapes of the KAF system did adjust their orientation to match both the positive and negative levels of surface inclination. In general, the ankle appears to be the main adapting joint when walking up inclined surfaces while the knee becomes important for the overall adaptation in downhill walking. Knowledge of physiological lower-limb roll-over characteristics on ramped surfaces may help in the development of biomimetic prostheses and orthoses that will automatically adapt to changes in walking surface inclination. PMID:15664674

  16. Walking behaviour of healthy elderly: attention should be paid

    PubMed Central

    2010-01-01

    Background Previous studies have reported an association between executive function (EF) and measures of gait, particularly among older adults. This study examined the relationship between specific components of executive functions and the relative dual task costs of gait (DTC) in community-dwelling non-demented older adults, aged 65 years and older. Methods Temporal (stride time, stride velocity) and spatial (stride length) gait characteristics were measured using a GAITRite-System among 62 healthy community dwelling older adults while walking with and without backward counting (BC) at preferred and fast walking speeds. Specific executive functions divided attention, memory and inhibition were assessed using the Test for Attentional Performance (TAP). Other measures included Mini-Mental State Examination (MMSE), amount of daily medications taken, educational level and sociodemographic characteristics. Adjusted and unadjusted multivariable linear regression models were developed to assess the relations between variables. Results High relative DTC for stride time, stride velocity and stride length were associated with divided attention at fast walking speed. High relative DTC for stride time was associated with divided attention at preferred walking speed. The association between high DTC of stride length and memory was less robust and only observable at preferred walking speed. None of the gait measures was associated with inhibition. Conclusions Spatial and temporal dual task cost characteristics of gait are especially associated with divided attention in older adults. The results showed that the associated DTC differ by executive function and the nature of the task (preferred versus fast walking). Further research is warranted to determine whether improvement in divided attention translates to better performance on selected complex walking tasks. PMID:20939911

  17. Biomechanics and energetics of walking on uneven terrain

    PubMed Central

    Voloshina, Alexandra S.; Kuo, Arthur D.; Daley, Monica A.; Ferris, Daniel P.

    2013-01-01

    SUMMARY Walking on uneven terrain is more energetically costly than walking on smooth ground, but the biomechanical factors that contribute to this increase are unknown. To identify possible factors, we constructed an uneven terrain treadmill that allowed us to record biomechanical, electromyographic and metabolic energetics data from human subjects. We hypothesized that walking on uneven terrain would increase step width and length variability, joint mechanical work and muscle co-activation compared with walking on smooth terrain. We tested healthy subjects (N=11) walking at 1.0 m s?1, and found that, when walking on uneven terrain with up to 2.5 cm variation, subjects decreased their step length by 4% and did not significantly change their step width, while both step length and width variability increased significantly (22 and 36%, respectively; P<0.05). Uneven terrain walking caused a 28 and 62% increase in positive knee and hip work, respectively, and a 26% greater magnitude of negative knee work (0.0106, 0.1078 and 0.0425 J kg?1, respectively; P<0.05). Mean muscle activity increased in seven muscles in the lower leg and thigh (P<0.05). These changes caused overall net metabolic energy expenditure to increase by 0.73 W kg?1 (28%; P<0.0001). Much of that increase could be explained by the increased mechanical work observed at the knee and hip. Greater muscle co-activation could also contribute to increased energetic cost but to unknown degree. The findings provide insight into how lower limb muscles are used differently for natural terrain compared with laboratory conditions. PMID:23913951

  18. A mechanical protocol to replicate impact in walking footwear.

    PubMed

    Price, Carina; Cooper, Glen; Graham-Smith, Philip; Jones, Richard

    2014-01-01

    Impact testing is undertaken to quantify the shock absorption characteristics of footwear. The current widely reported mechanical testing method mimics the heel impact in running and therefore applies excessive energy to walking footwear. The purpose of this study was to modify the ASTM protocol F1614 (Procedure A) to better represent walking gait. This was achieved by collecting kinematic and kinetic data while participants walked in four different styles of walking footwear (trainer, oxford shoe, flip-flop and triple-density sandal). The quantified heel-velocity and effective mass at ground-impact were then replicated in a mechanical protocol. The kinematic data identified different impact characteristics in the footwear styles. Significantly faster heel velocity towards the floor was recorded walking in the toe-post sandals (flip-flop and triple-density sandal) compared with other conditions (e.g. flip-flop: 0.360.05 ms(-1) versus trainer: 0.180.06 ms(-1)). The mechanical protocol was adapted by altering the mass and drop height specific to the data captured for each shoe (e.g. flip-flop: drop height 7 mm, mass 16.2 kg). As expected, the adapted mechanical protocol produced significantly lower peak force and accelerometer values than the ASTM protocol (p<.001). The mean difference between the human and adapted protocol was 12.717.5% (p<.001) for peak acceleration and 25.217.7% (p=.786) for peak force. This paper demonstrates that altered mechanical test protocols can more closely replicate loading on the lower limb in walking. This therefore suggests that testing of material properties of footbeds not only needs to be gait style specific (e.g. running versus walking), but also footwear style specific. PMID:24618371

  19. Increased walking variability in elderly persons with congestive heart failure

    NASA Technical Reports Server (NTRS)

    Hausdorff, J. M.; Forman, D. E.; Ladin, Z.; Goldberger, A. L.; Rigney, D. R.; Wei, J. Y.

    1994-01-01

    OBJECTIVES: To determine the effects of congestive heart failure on a person's ability to walk at a steady pace while ambulating at a self-determined rate. SETTING: Beth Israel Hospital, Boston, a primary and tertiary teaching hospital, and a social activity center for elderly adults living in the community. PARTICIPANTS: Eleven elderly subjects (aged 70-93 years) with well compensated congestive heart failure (NY Heart Association class I or II), seven elderly subjects (aged 70-79 years) without congestive heart failure, and 10 healthy young adult subjects (aged 20-30 years). MEASUREMENTS: Subjects walked for 8 minutes on level ground at their own selected walking rate. Footswitches were used to measure the time between steps. Step rate (steps/minute) and step rate variability were calculated for the entire walking period, for 30 seconds during the first minute of the walk, for 30 seconds during the last minute of the walk, and for the 30-second period when each subject's step rate variability was minimal. Group means and 5% and 95% confidence intervals were computed. MAIN RESULTS: All measures of walking variability were significantly increased in the elderly subjects with congestive heart failure, intermediate in the elderly controls, and lowest in the young subjects. There was no overlap between the three groups using the minimal 30-second variability (elderly CHF vs elderly controls: P < 0.001, elderly controls vs young: P < 0.001), and no overlap between elderly subjects with and without congestive heart failure when using the overall variability. For all four measures, there was no overlap in any of the confidence intervals, and all group means were significantly different (P < 0.05).

  20. Walking at the preferred stride frequency minimizes muscle activity.

    PubMed

    Russell, Daniel M; Apatoczky, Dylan T

    2016-03-01

    This study determined whether walking at the preferred stride frequency minimizes muscle activity compared with other cadences at the same speed. Anthropometric measurements were recorded from 10 subjects and used to estimate their predicted resonant stride frequency. The preferred walking speed and stride frequency were determined from freely adopted walking on a treadmill. For the experimental trials the treadmill was set at each individual's preferred walking speed. Participants walked for 6min at eight cadences prescribed by an auditory metronome: preferred stride frequency and -35, -25, -15, 0, +15, +25, +35% of predicted resonant stride frequency. Oxygen consumption was measured via gas analysis. Muscle activity of the right leg gastrocnemius (GA), tibialis anterior (TA), biceps femoris (BF) and rectus femoris (RF) muscles was recorded via electromyography (EMG). On average, participants preferred to walk with a stride frequency .07Hz lower than their predicted resonant stride frequency, however a strong positive correlation was observed between these variables. Stride frequency had a significant and large quadratic effect on VO2 (RLR(2)=.76), and activity of the GA (RLR(2)=.66), TA (RLR(2)=.83), BF (RLR(2)=.70) and RF (RLR(2)=.78) muscles. VO2, GA and TA activity were all minimal at the preferred stride frequency and increased for faster or slower cadences. BF and RF activity were minimal across a broad range of slow frequencies including the preferred stride frequency and increased for faster frequencies. The preferred stride frequency that humans readily adopt during walking minimizes the activation of the GA, TA, BF and RF muscles, which in turn minimizes the overall metabolic cost. PMID:26979903

  1. Quadratus femoris: An EMG investigation during walking and running.

    PubMed

    Semciw, Adam I; Freeman, Michael; Kunstler, Breanne E; Mendis, M Dilani; Pizzari, Tania

    2015-09-18

    Dysfunction of hip stabilizing muscles such as quadratus femoris (QF) is identified as a potential source of lower extremity injury during functional tasks like running. Despite these assumptions, there are currently no electromyography (EMG) data that establish the burst activity profile of QF during any functional task like walking or running. The objectives of this study were to characterize and compare the EMG activity profile of QF while walking and running (primary aim) and describe the direction specific action of QF (secondary aim). A bipolar fine-wire intramuscular electrode was inserted via ultrasound guidance into the QF of 10 healthy participants (4 females). Ensemble curves were generated from four walking and running trials, and normalized to maximum voluntary isometric contractions (MVICs). Paired t-tests compared the temporal and amplitude EMG variables. The relative activity of QF in the MVICs was calculated. The QF displayed moderate to high amplitude activity in the stance phase of walking and very high activity during stance in running. During swing, there was minimal QF activity recorded during walking and high amplitudes were present while running (run vs walk effect size=4.23, P<0.001). For the MVICs, external rotation and clam produced the greatest QF activity, with the hip in the anatomical position. This study provides an understanding of the activity demands placed on QF while walking and running. The high activity in late swing during running may signify a synergistic role with other posterior thigh muscles to control deceleration of the limb in preparation for stance. PMID:26116043

  2. Walking Adaptability after a Stroke and Its Assessment in Clinical Settings

    PubMed Central

    Balasubramanian, Chitralakshmi K.; Clark, David J.; Fox, Emily J.

    2014-01-01

    Control of walking has been described by a tripartite model consisting of stepping, equilibrium, and adaptability. This review focuses on walking adaptability, which is defined as the ability to modify walking to meet task goals and environmental demands. Walking adaptability is crucial to safe ambulation in the home and community environments and is often severely compromised after a stroke. Yet quantification of walking adaptability after stroke has received relatively little attention in the clinical setting. The objectives of this review were to examine the conceptual challenges for clinical measurement of walking adaptability and summarize the current state of clinical assessment for walking adaptability. We created nine domains of walking adaptability from dimensions of community mobility to address the conceptual challenges in measurement and reviewed performance-based clinical assessments of walking to determine if the assessments measure walking adaptability in these domains. Our literature review suggests the lack of a comprehensive well-tested clinical assessment tool for measuring walking adaptability. Accordingly, recommendations for the development of a comprehensive clinical assessment of walking adaptability after stroke have been presented. Such a clinical assessment will be essential for gauging recovery of walking adaptability with rehabilitation and for motivating novel strategies to enhance recovery of walking adaptability after stroke. PMID:25254140

  3. Give your ideas some legs: the positive effect of walking on creative thinking.

    PubMed

    Oppezzo, Marily; Schwartz, Daniel L

    2014-07-01

    Four experiments demonstrate that walking boosts creative ideation in real time and shortly after. In Experiment 1, while seated and then when walking on a treadmill, adults completed Guilford's alternate uses (GAU) test of creative divergent thinking and the compound remote associates (CRA) test of convergent thinking. Walking increased 81% of participants' creativity on the GAU, but only increased 23% of participants' scores for the CRA. In Experiment 2, participants completed the GAU when seated and then walking, when walking and then seated, or when seated twice. Again, walking led to higher GAU scores. Moreover, when seated after walking, participants exhibited a residual creative boost. Experiment 3 generalized the prior effects to outdoor walking. Experiment 4 tested the effect of walking on creative analogy generation. Participants sat inside, walked on a treadmill inside, walked outside, or were rolled outside in a wheelchair. Walking outside produced the most novel and highest quality analogies. The effects of outdoor stimulation and walking were separable. Walking opens up the free flow of ideas, and it is a simple and robust solution to the goals of increasing creativity and increasing physical activity. PMID:24749966

  4. Treadmill Training Improves Overground Walking Economy in Parkinsons Disease: A Randomized, Controlled Pilot Study

    PubMed Central

    Fernndez-del-Olmo, Miguel Angel; Sanchez, Jose Andres; Bello, Olalla; Lopez-Alonso, Virginia; Mrquez, Gonzalo; Morenilla, Luis; Castro, Xabier; Giraldez, Manolo; Santos-Garca, Diego

    2014-01-01

    Gait disturbances are one of the principal and most incapacitating symptoms of Parkinsons disease (PD). In addition, walking economy is impaired in PD patients and could contribute to excess fatigue in this population. An important number of studies have shown that treadmill training can improve kinematic parameters in PD patients. However, the effects of treadmill and overground walking on the walking economy remain unknown. The goal of this study was to explore the walking economy changes in response to a treadmill and an overground training program, as well as the differences in the walking economy during treadmill and overground walking. Twenty-two mild PD patients were randomly assigned to a treadmill or overground training group. The training program consisted of 5?weeks (3 sessions/week). We evaluated the energy expenditure of overground walking, before and after each of the training programs. The energy expenditure of treadmill walking (before the program) was also evaluated. The treadmill, but not the overground training program, lead to an improvement in the walking economy (the rate of oxygen consumed per distance during overground walking at a preferred speed) in PD patients. In addition, walking on a treadmill required more energy expenditure compared with overground walking at the same speed. This study provides evidence that in mild PD patients, treadmill training is more beneficial compared with that of walking overground, leading to a greater improvement in the walking economy. This finding is of clinical importance for the therapeutic administration of exercise in PD. PMID:25309510

  5. Neighbourhood walkability, daily steps and utilitarian walking in Canadian adults

    PubMed Central

    Hajna, Samantha; Ross, Nancy A; Joseph, Lawrence; Harper, Sam; Dasgupta, Kaberi

    2015-01-01

    Objectives To estimate the associations of neighbourhood walkability (based on Geographic Information System (GIS)-derived measures of street connectivity, land use mix, and population density and the Walk Score) with self-reported utilitarian walking and accelerometer-assessed daily steps in Canadian adults. Design A cross-sectional analysis of data collected as part of the Canadian Health Measures Survey (20072009). Setting Home neighbourhoods (500?m polygonal street network buffers around the centroid of the participant's postal code) located in Atlantic Canada, Qubec, Ontario, the Prairies and British Columbia. Participants 5605 individuals participated in the survey. 3727 adults (?18?years) completed a computer-assisted interview and attended a mobile clinic assessment. Analyses were based on those who had complete exposure, outcome and covariate data (n=2949). Main exposure measures GIS-derived walkability (based on land use mix, street connectivity and population density); Walk Score. Main outcome measures Self-reported utilitarian walking; accelerometer-assessed daily steps. Results No important relationship was observed between neighbourhood walkability and daily steps. Participants who reported more utilitarian walking, however, accumulated more steps (<1?h/week: 6613 steps/day, 95% CI 6251 to 6975; 1 to 5?h/week: 6768 steps/day, 95% CI 6420 to 7117; ?6?h/week: 7391 steps/day, 95% CI 6972 to 7811). There was a positive graded association between walkability and odds of walking ?1?h/week for utilitarian purposes (eg, Q4 vs Q1 of GIS-derived walkability: OR=1.66, 95% CI 1.31 to 2.11; Q3 vs Q1: OR=1.41, 95% CI 1.14 to 1.76; Q2 vs Q1: OR=1.13, 95% CI 0.91 to 1.39) independent of age, sex, body mass index, married/common law status, annual household income, having children in the household, immigrant status, mood disorder, perceived health, ever smoker and season. Conclusions Contrary to expectations, living in more walkable Canadian neighbourhoods was not associated with more total walking. Utilitarian walking and daily steps were, however, correlated and walkability demonstrated a positive graded relationship with utilitarian walking. PMID:26603246

  6. Interactive cueing with walk-Mate for Hemiparetic Stroke Rehabilitation

    PubMed Central

    2012-01-01

    Background Many techniques that compensate for locomotion problems in daily life using externally controlled stimulation have recently been reported. These techniques are beneficial for effortlessly supporting patients locomotive functions, but the users of such devices must necessarily remain dependent on them. It is possible that some individuals with gait impairment may be prevented recovering locomotive function. From a rehabilitation viewpoint, it may therefore be supposed that ideally, devices that can be used in daily life to improve the locomotive functions of the body itself should be proposed. Methods We evaluate the effectiveness of Walk-Mate, which has been used mainly as a gait compensation device, as a gait rehabilitation training device by analyzing improvement in locomotion before, during and after rehabilitation in hemiparetic patients and comparing it with a previous gait training method. Walk-Mate generates a model walking rhythm in response to a users locomotion in real time, and by indicating this rhythm using auditory stimuli, provides a technology that supports walking by reducing asymmetries and fluctuations in foot contact rhythm. If patients can use the system to learn a regulated walking rhythm, then it may also be expected to fulfil the functions of a gait rehabilitation training device for daily life. Results With regard to asymmetry, significantly improvements were seen for compensatory movement during training using Walk-Mate, but improvements were not retained as rehabilitative results. Regarding fluctuations in the foot contact period, significant improvement was observed for compensatory movement during training and these significant improvements were retained as rehabilitative results. In addition, it became clear that such improvement could not be adequately obtained by the previously proposed training technique utilizing constant rhythmic auditory stimulation. Conclusions Walk-Mate effectively compensated for locomotion problems of hemiparetic patients by improving gait rhythm both during and after training, suggesting that locomotive function can be effectively recovered in some patients. The interactive mechanism of Walk-Mate may be capable of simultaneously achieving the aims of gait compensation and gait rehabilitation training methods previously developed under individual frameworks. Walk-Mate is a promising technology for assisting the reintegration of disabled persons into society. PMID:22909032

  7. Task-dependent modification of leg motor neuron synaptic input underlying changes in walking direction and walking speed.

    PubMed

    Rosenbaum, Philipp; Schmitz, Josef; Schmidt, Joachim; Bschges, Ansgar

    2015-08-01

    Animals modify their behavior constantly to perform adequately in their environment. In terrestrial locomotion many forms of adaptation exist. Two tasks are changes of walking direction and walking speed. We investigated these two changes in motor output in the stick insect Cuniculina impigra to see how they are brought about at the level of leg motor neurons. We used a semi-intact preparation in which we can record intracellularly from leg motor neurons during walking. In this single-leg preparation the middle leg of the animal steps in a vertical plane on a treadwheel. Stimulation of either abdomen or head reliably elicits fictive forward or backward motor activity, respectively, in the fixed and otherwise deafferented thorax-coxa joint. With a change of walking direction only thorax-coxa-joint motor neurons protractor and retractor changed their activity. The protractor switched from swing activity during forward to stance activity during backward walking, and the retractor from stance to swing. This phase switch was due to corresponding change of phasic synaptic inputs from inhibitory to excitatory and vice versa at specific phases of the step cycle. In addition to phasic synaptic input a tonic depolarization of the motor neurons was present. Analysis of changes in stepping velocity during stance showed only a significant correlation to flexor motor neuron activity, but not to that of retractor and depressor motor neurons during forward walking. These results show that different tasks in the stick insect walking system are generated by altering synaptic inputs to specific leg joint motor neurons only. PMID:26063769

  8. Compliant leg behaviour explains basic dynamics of walking and running.

    PubMed

    Geyer, Hartmut; Seyfarth, Andre; Blickhan, Reinhard

    2006-11-22

    The basic mechanics of human locomotion are associated with vaulting over stiff legs in walking and rebounding on compliant legs in running. However, while rebounding legs well explain the stance dynamics of running, stiff legs cannot reproduce that of walking. With a simple bipedal spring-mass model, we show that not stiff but compliant legs are essential to obtain the basic walking mechanics; incorporating the double support as an essential part of the walking motion, the model reproduces the characteristic stance dynamics that result in the observed small vertical oscillation of the body and the observed out-of-phase changes in forward kinetic and gravitational potential energies. Exploring the parameter space of this model, we further show that it not only combines the basic dynamics of walking and running in one mechanical system, but also reveals these gaits to be just two out of the many solutions to legged locomotion offered by compliant leg behaviour and accessed by energy or speed. PMID:17015312

  9. Steady and transient coordination structures of walking and running.

    PubMed

    Lamoth, C J C; Daffertshofer, A; Huys, R; Beek, P J

    2009-06-01

    We studied multisegmental coordination and stride characteristics in nine participants while walking and running on a treadmill. The study's main aim was to evaluate the coordination patterns of walking and running and their variance as a function of locomotion speed, with a specific focus on gait transitions and accompanying features like hysteresis and critical fluctuations. Stride characteristics changed systematically with speed in a gait-dependent fashion, but exhibited no hysteresis. Multisegmental coordination of walking and running was captured by four principal components, the first two of which were present in both gaits. Locomotion speed had subtle yet systematic differential effects on the relative phasing between the identified components in both walking and running and its variance, in particular in the immediate vicinity of gait transitions. Unlike the stride characteristics, the identified coordination patterns revealed clear evidence of both hysteresis and critical fluctuations around transition points. Overall, the results suggest that walking and running entail similar, albeit speed- and gait-dependent, coordination structures, and that gait transitions bear signatures of nonequilibrium phase transitions. Application of multivariate analyses of whole-body recordings appears crucial to detect these features in a reliable fashion. PMID:19027972

  10. Kinematic Strategies for Walking Across a Destabilizing Rock Surface✩

    PubMed Central

    Gates, Deanna H.; Wilken, Jason M.; Scott, Shawn J.; Sinitski, Emily H.; Dingwell, Jonathan B.

    2011-01-01

    It is important to understand how people adapt their gait when walking in real-world conditions with variable surface characteristics. This study quantified lower-extremity joint kinematics, estimated whole body center of mass height (COMVT), and minimum toe clearance (MTC) while fifteen healthy, young subjects walked on level ground (LG) and a destabilizing loose rock surface (RS) at four controlled speeds. There were no significant differences in average step parameters (length, time, or width) between the walking surfaces. However, the variability of these parameters increased twofold on the RS compared to LG. When walking on the RS, subjects contacted the surface with a flatter foot and increased knee and hip flexion, which enabled them to lower COMVT. Subjects exhibited increased hip and knee flexion and ankle dorsiflexion during swing on the RS. These changes contributed to a 3.8 times greater MTC on the RS compared to LG. Peak hip and knee flexion during early stance and swing increased with walking speed, contributing to decreased COMVT and increased MTC. Overall, subjects systematically adapted their movement kinematics to overcome the challenge imposed by the destabilizing loose rock surface. PMID:21890361

  11. Random walks of colloidal probes in viscoelastic materials.

    PubMed

    Khan, Manas; Mason, Thomas G

    2014-04-01

    To overcome limitations of using a single fixed time step in random walk simulations, such as those that rely on the classic Wiener approach, we have developed an algorithm for exploring random walks based on random temporal steps that are uniformly distributed in logarithmic time. This improvement enables us to generate random-walk trajectories of probe particles that span a highly extended dynamic range in time, thereby facilitating the exploration of probe motion in soft viscoelastic materials. By combining this faster approach with a Maxwell-Voigt model (MVM) of linear viscoelasticity, based on a slowly diffusing harmonically bound Brownian particle, we rapidly create trajectories of spherical probes in soft viscoelastic materials over more than 12 orders of magnitude in time. Appropriate windowing of these trajectories over different time intervals demonstrates that random walk for the MVM is neither self-similar nor self-affine, even if the viscoelastic material is isotropic. We extend this approach to spatially anisotropic viscoelastic materials, using binning to calculate the anisotropic mean square displacements and creep compliances along different orthogonal directions. The elimination of a fixed time step in simulations of random processes, including random walks, opens up interesting possibilities for modeling dynamics and response over a highly extended temporal dynamic range. PMID:24827253

  12. Mindful Walking in Psychologically Distressed Individuals: A Randomized Controlled Trial

    PubMed Central

    Teut, M.; Roesner, E. J.; Ortiz, M.; Reese, F.; Binting, S.; Roll, S.; Fischer, H. F.; Michalsen, A.; Willich, S. N.; Brinkhaus, B.

    2013-01-01

    Background. The aim of this randomized, controlled study was to investigate the effectiveness of a mindful walking program in patients with high levels of perceived psychological distress. Methods. Participants aged between 18 and 65 years with moderate to high levels of perceived psychological distress were randomized to 8 sessions of mindful walking in 4 weeks (each 40 minutes walking, 10 minutes mindful walking, 10 minutes discussion) or to no study intervention (waiting group). Primary outcome parameter was the difference to baseline on Cohen's Perceived Stress Scale (CPSS) after 4 weeks between intervention and control. Results. Seventy-four participants were randomized in the study; 36 (32 female, 52.3 8.6 years) were allocated to the intervention and 38 (35 female, 49.5 8.8 years) to the control group. Adjusted CPSS differences after 4 weeks were ?8.8 [95% CI: ?10.8; ?6.8] (mean 24.2 [22.2; 26.2]) in the intervention group and ?1.0 [?2.9; 0.9] (mean 32.0 [30.1; 33.9]) in the control group, resulting in a highly significant group difference (P < 0.001). Conclusion. Patients participating in a mindful walking program showed reduced psychological stress symptoms and improved quality of life compared to no study intervention. Further studies should include an active treatment group and a long-term follow-up. PMID:23983786

  13. Search for Directed Networks by Different Random Walk Strategies

    NASA Astrophysics Data System (ADS)

    Zhu, Zi-Qi; Jin, Xiao-Ling; Huang, Zhi-Long

    2012-03-01

    A comparative study is carried out on the efficiency of five different random walk strategies searching on directed networks constructed based on several typical complex networks. Due to the difference in search efficiency of the strategies rooted in network clustering, the clustering coefficient in a random walker's eye on directed networks is defined and computed to be half of the corresponding undirected networks. The search processes are performed on the directed networks based on ErdsRnyi model, WattsStrogatz model, BarabsiAlbert model and clustered scale-free network model. It is found that self-avoiding random walk strategy is the best search strategy for such directed networks. Compared to unrestricted random walk strategy, path-iteration-avoiding random walks can also make the search process much more efficient. However, no-triangle-loop and no-quadrangle-loop random walks do not improve the search efficiency as expected, which is different from those on undirected networks since the clustering coefficient of directed networks are smaller than that of undirected networks.

  14. Percolation assisted excitation transport in discrete-time quantum walks

    NASA Astrophysics Data System (ADS)

    Štefaňák, M.; Novotný, J.; Jex, I.

    2016-02-01

    Coherent transport of excitations along chains of coupled quantum systems represents an interesting problem with a number of applications ranging from quantum optics to solar cell technology. A convenient tool for studying such processes are quantum walks. They allow us to determine all the process features in a quantitative way. We study the survival probability and the transport efficiency on a simple, highly symmetric graph represented by a ring. The propagation of excitation is modeled by a discrete-time (coined) quantum walk. For a two-state quantum walk, where the excitation (walker) has to leave its actual position to the neighboring sites, the survival probability decays exponentially and the transport efficiency is unity. The decay rate of the survival probability can be estimated using the leading eigenvalue of the evolution operator. However, if the excitation is allowed to stay at its present position, i.e. the propagation is modeled by a lazy quantum walk, then part of the wave-packet can be trapped in the vicinity of the origin and never reaches the sink. In such a case, the survival probability does not vanish and the excitation transport is not efficient. The dependency of the transport efficiency on the initial state is determined. Nevertheless, we show that for some lazy quantum walks dynamical, percolations of the ring eliminate the trapping effect and efficient excitation transport can be achieved.

  15. A university, community coalition, and town partnership to promote walking.

    PubMed

    Griffin, Sarah F; Williams, Joel E; Hickman, Powell; Kirchner, Amber; Spitler, Hugh

    2011-01-01

    Less than half of all US adults report meeting physical activity recommendations of 30 minutes or more of moderate to vigorous physical activity on at least 5 days per week. Thus, community-wide ecological initiatives are needed to create environments that support incorporating physical activity into residents' daily lives. In this article we describe an ongoing collaborative service-learning partnership between Clemson University, a community coalition, and a neighboring small rural town to address local social and physical environment supports for walking. Years 1 to 3 of this collaborative initiative were evaluated using a mixed-method approach to assess physical environment changes, social environment changes, community perceptions of support for walking, community perceptions of collaborating with university students, and students' skill development. Results revealed several key environmental changes such as mapping and marking 3 walking trails in the community, development of broad marketing efforts linked to the trails that promote community health and heritage, and annual community events to promote walking and the newly developed walking trails. Interview data with community leaders identified several key themes critical to facilitating and enhancing our university and community collaboration. Lastly, students developed skills in developing partnerships, mapping, advocacy, event planning, critical reflection, and qualitative and quantitative data collection and analysis. Through this process community members and students learn evidence-based public health skills for using data and planning frameworks to guide local initiatives, engage community members in decision making, and conducting evaluations. PMID:21617413

  16. A discrete time random walk model for anomalous diffusion

    NASA Astrophysics Data System (ADS)

    Angstmann, C. N.; Donnelly, I. C.; Henry, B. I.; Nichols, J. A.

    2015-07-01

    The continuous time random walk, introduced in the physics literature by Montroll and Weiss, has been widely used to model anomalous diffusion in external force fields. One of the features of this model is that the governing equations for the evolution of the probability density function, in the diffusion limit, can generally be simplified using fractional calculus. This has in turn led to intensive research efforts over the past decade to develop robust numerical methods for the governing equations, represented as fractional partial differential equations. Here we introduce a discrete time random walk that can also be used to model anomalous diffusion in an external force field. The governing evolution equations for the probability density function share the continuous time random walk diffusion limit. Thus the discrete time random walk provides a novel numerical method for solving anomalous diffusion equations in the diffusion limit, including the fractional Fokker-Planck equation. This method has the clear advantage that the discretisation of the diffusion limit equation, which is necessary for numerical analysis, is itself a well defined physical process. Some examples using the discrete time random walk to provide numerical solutions of the probability density function for anomalous subdiffusion, including forcing, are provided.

  17. Quantum walk coherences on a dynamical percolation graph

    PubMed Central

    Elster, Fabian; Barkhofen, Sonja; Nitsche, Thomas; Novotný, Jaroslav; Gábris, Aurél; Jex, Igor; Silberhorn, Christine

    2015-01-01

    Coherent evolution governs the behaviour of all quantum systems, but in nature it is often subjected to influence of a classical environment. For analysing quantum transport phenomena quantum walks emerge as suitable model systems. In particular, quantum walks on percolation structures constitute an attractive platform for studying open system dynamics of random media. Here, we present an implementation of quantum walks differing from the previous experiments by achieving dynamical control of the underlying graph structure. We demonstrate the evolution of an optical time-multiplexed quantum walk over six double steps, revealing the intricate interplay between the internal and external degrees of freedom. The observation of clear non-Markovian signatures in the coin space testifies the high coherence of the implementation and the extraordinary degree of control of all system parameters. Our work is the proof-of-principle experiment of a quantum walk on a dynamical percolation graph, paving the way towards complex simulation of quantum transport in random media. PMID:26311434

  18. Impact of brisk walking and aerobics in overweight women

    PubMed Central

    Melam, Ganeswara Rao; Alhusaini, Adel A; Buragadda, Syamala; Kaur, Taranpreet; Khan, Imran Ali

    2016-01-01

    [Purpose] Lack of physical activity and an uncontrolled diet cause excessive weight gain, which leads to obesity and other metabolic disorders. Studies have indicated that brisk walking and aerobics are the best methods for controlling and reducing weight and body mass composition. [Subjects and Methods] In this study, 45 overweight women were enrolled and divided into 3 groups. Women not involved in brisk walking or aerobics were included in group A (n = 15) as control subjects; women involved in brisk walking were in group B (n = 15); and those involved in aerobics were in group C (n = 15). [Results] This program was carried out 5 days/week for 10 weeks. Pre- and post-measurements of body mass index, waist and hip circumference, and skinfold thickness of the abdomen, subscapular area, biceps, and triceps were recorded for the women in all 3 groups. All values decreased in women who participated in brisk walking and aerobics for 10 weeks. [Conclusion] These results indicate that aerobics with diet therapy is a more effective intervention program for controlling and reducing body mass index and skinfold thickness than brisk walking with diet therapy in North Indian women. PMID:26957777

  19. EMG patterns during assisted walking in the exoskeleton

    PubMed Central

    Sylos-Labini, Francesca; La Scaleia, Valentina; d'Avella, Andrea; Pisotta, Iolanda; Tamburella, Federica; Scivoletto, Giorgio; Molinari, Marco; Wang, Shiqian; Wang, Letian; van Asseldonk, Edwin; van der Kooij, Herman; Hoellinger, Thomas; Cheron, Guy; Thorsteinsson, Freygardur; Ilzkovitz, Michel; Gancet, Jeremi; Hauffe, Ralf; Zanov, Frank; Lacquaniti, Francesco; Ivanenko, Yuri P.

    2014-01-01

    Neuroprosthetic technology and robotic exoskeletons are being developed to facilitate stepping, reduce muscle efforts, and promote motor recovery. Nevertheless, the guidance forces of an exoskeleton may influence the sensory inputs, sensorimotor interactions and resulting muscle activity patterns during stepping. The aim of this study was to report the muscle activation patterns in a sample of intact and injured subjects while walking with a robotic exoskeleton and, in particular, to quantify the level of muscle activity during assisted gait. We recorded electromyographic (EMG) activity of different leg and arm muscles during overground walking in an exoskeleton in six healthy individuals and four spinal cord injury (SCI) participants. In SCI patients, EMG activity of the upper limb muscles was augmented while activation of leg muscles was typically small. Contrary to our expectations, however, in neurologically intact subjects, EMG activity of leg muscles was similar or even larger during exoskeleton-assisted walking compared to normal overground walking. In addition, significant variations in the EMG waveforms were found across different walking conditions. The most variable pattern was observed in the hamstring muscles. Overall, the results are consistent with a non-linear reorganization of the locomotor output when using the robotic stepping devices. The findings may contribute to our understanding of human-machine interactions and adaptation of locomotor activity patterns. PMID:24982628

  20. Robotic-assessment of walking in individuals with gait disorders.

    PubMed

    Hidler, J

    2004-01-01

    Walking deficits are a common bi-product of numerous neurological injuries, such as stroke and spinal cord injury. A number of new therapeutic interventions, such as body-weight supported locomotor training and robotic technologies aim to improve walking function and reduce co-morbidities. Currently, there is no way to determine what the optimal set of training parameters are for maximizing step performance. This paper presents a technique for estimating the walking performance of individuals with gait disorders using a robotic-orthosis. The device, called the Lokomat is coupled to the subject through instrumented leg cuffs, while the split-belt treadmill on which the subject walks is instrumented with piezo-electric force sensors allowing for the calculation of ground reaction forces and center of pressure. Using this data, a real-time inverse dynamics approach can be used to estimate the kinetics and kinematics of the subject, and when combined with electromyographic (EMG) data, the set of training conditions through which the subject generates the most appropriate EMG patterns and joint moments can be identified. The proposed technique will for the first time provide clinicians a way of determining the optimal gait training parameters for each individual, and also track their functional recovery throughout their neurorehabilitation program. It is postulated that training at the conditions that maximizes stepping performance will lead to higher gains in over-ground walking ability. PMID:17271392

  1. Current-reinforced random walks for constructing transport networks

    PubMed Central

    Ma, Qi; Johansson, Anders; Tero, Atsushi; Nakagaki, Toshiyuki; Sumpter, David J. T.

    2013-01-01

    Biological systems that build transport networks, such as trail-laying ants and the slime mould Physarum, can be described in terms of reinforced random walks. In a reinforced random walk, the route taken by ‘walking’ particles depends on the previous routes of other particles. Here, we present a novel form of random walk in which the flow of particles provides this reinforcement. Starting from an analogy between electrical networks and random walks, we show how to include current reinforcement. We demonstrate that current-reinforcement results in particles converging on the optimal solution of shortest path transport problems, and avoids the self-reinforcing loops seen in standard density-based reinforcement models. We further develop a variant of the model that is biologically realistic, in the sense that the particles can be identified as ants and their measured density corresponds to those observed in maze-solving experiments on Argentine ants. For network formation, we identify the importance of nonlinear current reinforcement in producing networks that optimize both network maintenance and travel times. Other than ant trail formation, these random walks are also closely related to other biological systems, such as blood vessels and neuronal networks, which involve the transport of materials or information. We argue that current reinforcement is likely to be a common mechanism in a range of systems where network construction is observed. PMID:23269849

  2. Mobile gaze tracking system for outdoor walking behavioral studies

    PubMed Central

    Tomasi, Matteo; Pundlik, Shrinivas; Bowers, Alex R.; Peli, Eli; Luo, Gang

    2016-01-01

    Most gaze tracking techniques estimate gaze points on screens, on scene images, or in confined spaces. Tracking of gaze in open-world coordinates, especially in walking situations, has rarely been addressed. We use a head-mounted eye tracker combined with two inertial measurement units (IMU) to track gaze orientation relative to the heading direction in outdoor walking. Head movements relative to the body are measured by the difference in output between the IMUs on the head and body trunk. The use of the IMU pair reduces the impact of environmental interference on each sensor. The system was tested in busy urban areas and allowed drift compensation for long (up to 18 min) gaze recording. Comparison with ground truth revealed an average error of 3.3° while walking straight segments. The range of gaze scanning in walking is frequently larger than the estimation error by about one order of magnitude. Our proposed method was also tested with real cases of natural walking and it was found to be suitable for the evaluation of gaze behaviors in outdoor environments. PMID:26894511

  3. Going round the bend: Persistent personal biases in walked angles.

    PubMed

    Jetzschke, Simon; Ernst, Marc O; Moscatelli, Alessandro; Boeddeker, Norbert

    2016-03-23

    For navigation through our environment, we can rely on information from various modalities, such as vision and audition. This information enables us for example to estimate our position relative to the starting position, or to integrate velocity and acceleration signals from the vestibular organ and proprioception to estimate the displacement due to self-motion. To better understand the mechanisms that underlie human navigation we analysed the performance of participants in an angle-walking task in the absence of visual and auditory signals. To this end, we guided them along paths of different lengths and asked them to turn by an angle of ±90°. We found significant biases in turn angles, i.e. systematic deviations from the correct angle and that these were characteristic for individual participants. Varying path length, however, had little effect on turn accuracy and precision. To check whether this idiosyncrasy was persistent over time and present in another type of walking task, we performed a second experiment several weeks later. Here, the same participants were guided to walk angles with varying amplitude. We then asked them to judge whether they had walked an angle larger or smaller than 90° in a two-alternative forced-choice paradigm. The personal bias was highly correlated between the two experiments even though they were conducted weeks apart. The presence of a persistent bias in walked angles in the absence of external directional cues indicates a possible error component for navigation, which is surprisingly time stable and idiosyncratic. PMID:26854843

  4. Dissipation of claudication pain after walking: implications for endurance training.

    PubMed

    Gardner, A W

    1993-08-01

    Although onset and maximal claudication pain are attained sooner as exercise intensity is increased, it is unclear whether dissipation of pain during recovery is altered. Thus, this study examined whether walking at gradually higher intensity would prolong the time needed for claudication pain to dissipate during recovery. Thirty patients with peripheral arterial disease (PAD) who were limited by claudication pain performed repeated progressive treadmill tests to assess walking capacity. Thereafter, each patient performed five treadmill tests at grades relative to their walking capacity (i.e., -4%, -2%, 0%, +2%, and +4% of the final grade attained with the progressive protocol). As expected, a curvilinear decrease in time to onset of claudication pain (191.1, 172.8, 132.8, 113.5, and 112.0 s; P < 0.05) and time to maximal claudication pain (394.2, 358.3, 260.5, 218.1, and 200.3 s; P < 0.05) were obtained with progressively higher grades. However, time needed for claudication pain to dissipate during supine recovery remained unchanged with increased walking intensity (358.5, 339.3, 359.9, 398.2, and 390.5 s; P = NS). In conclusion, when PAD patients walk to maximal claudication pain, dissipation of pain during recovery is similar whether the preceding exercise is performed at relatively low or high intensities. PMID:8371650

  5. When human walking becomes random walking: fractal analysis and modeling of gait rhythm fluctuations.

    PubMed

    Hausdorff, J M; Ashkenazy, Y; Peng, C K; Ivanov, P C; Stanley, H E; Goldberger, A L

    2001-12-15

    We present a random walk, fractal analysis of the stride-to-stride fluctuations in the human gait rhythm. The gait of healthy young adults is scale-free with long-range correlations extending over hundreds of strides. This fractal scaling changes characteristically with maturation in children and older adults and becomes almost completely uncorrelated with certain neurologic diseases. Stochastic modeling of the gait rhythm dynamics, based on transitions between different "neural centers", reproduces distinctive statistical properties of the gait pattern. By tuning one model parameter, the hopping (transition) range, the model can describe alterations in gait dynamics from childhood to adulthood including a decrease in the correlation and volatility exponents with maturation. PMID:12033228

  6. Mechanical and physiological effects of varying pole weights during Nordic walking compared to walking.

    PubMed

    Schiffer, Thorsten; Knicker, Axel; Montanarella, Melissa; Strder, Heiko K

    2011-06-01

    The study investigated the effect of varying pole weights on energy expenditure, upper limb muscle activation and on forces transmitted to the poles during Nordic walking (NW). Twelve women [age = 21 (2) years, body mass = 60.8 (6) kg, height = 1.71 (0.06) m] participated in five 7-min walking tests randomly chosen without poles (W), with normal NW poles (NW) or with added masses of 0.5 kg (NW + 0.5) 1.0 kg (NW + 1.0) or 1.5 kg (NW + 1.5) at a speed of 2 m s(-1). Heart rate (HR), relative oxygen uptake ([Formula: see text]), blood lactate (La) and rate of perceived exertion (RPE) were registered along with surface EMG (SEMG) from biceps brachii, triceps brachii, trapecius and deltoideus muscles. Inbuilt force transducers measured reaction forces along the long axes of the poles. NW + 0.5 and NW + 1.5 showed significant increases for [Formula: see text] and RPE compared with W (p < 0.05) but with no respective differences within NW. SEMG revealed higher activation of biceps brachii for all NW tests plus added masses compared to W (p < 0.05). Additionally the activation of biceps brachii was higher for NW + 1.5 compared to NW (p < 0.05). The contribution to overall activation duration of triceps brachii became lower but increased for biceps brachii with heavier poles. The increased energy expenditure during NW can be attributed to intensified muscle activation during forward swing of the poles. Heavier poles have no effect on energy expenditure compared to NW with usual poles but enhance muscular activity. Since there are no benefits concerning physiological and biomechanical parameters we do not recommend the use of heavier NW poles. PMID:21113789

  7. From Continuous-Time Random Walks to Continuous-Time Quantum Walks: Disordered Networks

    NASA Astrophysics Data System (ADS)

    Mülken, Oliver; Blumen, Alexander

    Recent years have seen a growing interest in dynamical quantum processes; thus it was found that the electronic energy transfer through photosynthetic antennae displays quantum features, aspects also known from the dynamics of charge carriers along polymer backbones. Hence, in modeling energy transfer one has to extend the classical, master-equation-type formalism and incorporate quantum-mechanical aspects, while still aiming to describe complex networks of molecules over which the transport takes place. The continuous time random walk (CTRW) scheme is widely employed in modeling transport in random environments (Sokolov et al, Phys Today 55:48, 2002) and is mathematically akin to quantum-mechanical Hamiltonians of tight-binding type (Mülken and Blumen, Phys Rep 502:37, 2011; Mülken and Blumen, Phys Rev E 73:066117, 2006); a simple way to see it is to focus on the time-evolution operators in statistical and in quantum mechanics: The transition to the quantal domain leads then to continuous-time quantum walks (CTQW). In this way the CTQW problem stays linear, and thus many results obtained in solving CTRW (such as eigenvalues and eigenfunctions) can be readily reutilized for CTQW. However, the physically relevant properties of the two models differ vastly: In the absence of traps CTQW are time-inversion symmetric and no energy equipartition takes place at long times. Also, the quantum system keeps memory of the initial conditions, a fact exemplified by the occurrence of quasi-revivals (Mülken and Blumen, Phys Rep 502:37, 2011). Here we will exemplify the vastly different behaviors of CTQW and CTRW on disordered networks , namely on small-world networks (Mülken et al, Phys Rev E 76:051125, 2007) and on star-graphs with randomly added bonds (Anishchenko et al, Quantum Inf Process 11:1273, 2012).

  8. A one-dimensional quantum walk with multiple-rotation on the coin

    PubMed Central

    Xue, Peng; Zhang, Rong; Qin, Hao; Zhan, Xiang; Bian, Zhihao; Li, Jian

    2016-01-01

    We introduce and analyze a one-dimensional quantum walk with two time-independent rotations on the coin. We study the influence on the property of quantum walk due to the second rotation on the coin. Based on the asymptotic solution in the long time limit, a ballistic behaviour of this walk is observed. This quantum walk retains the quadratic growth of the variance if the combined operator of the coin rotations is unitary. That confirms no localization exhibits in this walk. This result can be extended to the walk with multiple time-independent rotations on the coin. PMID:26822563

  9. A one-dimensional quantum walk with multiple-rotation on the coin.

    PubMed

    Xue, Peng; Zhang, Rong; Qin, Hao; Zhan, Xiang; Bian, Zhihao; Li, Jian

    2016-01-01

    We introduce and analyze a one-dimensional quantum walk with two time-independent rotations on the coin. We study the influence on the property of quantum walk due to the second rotation on the coin. Based on the asymptotic solution in the long time limit, a ballistic behaviour of this walk is observed. This quantum walk retains the quadratic growth of the variance if the combined operator of the coin rotations is unitary. That confirms no localization exhibits in this walk. This result can be extended to the walk with multiple time-independent rotations on the coin. PMID:26822563

  10. A one-dimensional quantum walk with multiple-rotation on the coin

    NASA Astrophysics Data System (ADS)

    Xue, Peng; Zhang, Rong; Qin, Hao; Zhan, Xiang; Bian, Zhihao; Li, Jian

    2016-01-01

    We introduce and analyze a one-dimensional quantum walk with two time-independent rotations on the coin. We study the influence on the property of quantum walk due to the second rotation on the coin. Based on the asymptotic solution in the long time limit, a ballistic behaviour of this walk is observed. This quantum walk retains the quadratic growth of the variance if the combined operator of the coin rotations is unitary. That confirms no localization exhibits in this walk. This result can be extended to the walk with multiple time-independent rotations on the coin.

  11. Walk-friendly suburbs for older adults? Exploring the enablers and barriers to walking in a large suburban municipality in Canada.

    PubMed

    Mitra, Raktim; Siva, Herthana; Kehler, Mark

    2015-12-01

    The neighbourhood environment may enable active aging by allowing the integration of walking into an older adult's daily routine. This study explores the relationship between the neighbourhood built environment and walking among a small group of older adults in a large suburban municipality in Canada. In-depth interviews using a photo-voice approach revealed that the participants walked largely to accumulated physical activity. Older adults who lived in either conventional residential or condominium neighbourhoods discussed poor traffic conditions and lack of benches/trees/places as barriers, and proximity to parks and access to shops as enablers to walking. Poor sidewalk quality, absence of street lights and personal safety concerns were major barriers to walking only for those living in suburban residential neighbourhoods. Our results indicate that high quality- and safe walking infrastructure may facilitate walking for physical activity among older adults living in the suburban communities. PMID:26568210

  12. Effects of a novel walking training program with postural correction and visual feedback on walking function in patients with post-stroke hemiparesis

    PubMed Central

    Won, Sang Hee; Kim, Jae Cheol; Oh, Duck-Won

    2015-01-01

    [Purpose] This study aimed to elucidate the effects of a novel walking training program with postural correction and visual feedback on walking function in patients with post-stroke hemiparesis. [Subjects] Sixteen subjects were randomly allocated to either the experimental group (EG) or the control group (CG), with eight subjects in each. [Methods] EG and CG subjects performed a 30-min treadmill walking training exercise twice daily for 2 weeks. EG subjects also underwent postural correction using elastic bands and received visual feedback during walking. The 10-m walk test was performed, and gait parameters were measured using a gait analysis system. [Results] All parameters showed significant main effects for the group factor and time-by-group interactions. Significant main effects for the time factor were found in the stride length and stance phase ratios. [Conclusion] The novel walking training program with postural correction and visual feedback may improve walking function in patients with post-stroke hemiparesis. PMID:26357443

  13. Superstatistical analysis and modelling of heterogeneous random walks

    PubMed Central

    Metzner, Claus; Mark, Christoph; Steinwachs, Julian; Lautscham, Lena; Stadler, Franz; Fabry, Ben

    2015-01-01

    Stochastic time series are ubiquitous in nature. In particular, random walks with time-varying statistical properties are found in many scientific disciplines. Here we present a superstatistical approach to analyse and model such heterogeneous random walks. The time-dependent statistical parameters can be extracted from measured random walk trajectories with a Bayesian method of sequential inference. The distributions and correlations of these parameters reveal subtle features of the random process that are not captured by conventional measures, such as the mean-squared displacement or the step width distribution. We apply our new approach to migration trajectories of tumour cells in two and three dimensions, and demonstrate the superior ability of the superstatistical method to discriminate cell migration strategies in different environments. Finally, we show how the resulting insights can be used to design simple and meaningful models of the underlying random processes. PMID:26108639

  14. Walking robot: A design project for undergraduate students

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The objective of the University of Maryland walking robot project was to design, analyze, assemble, and test an intelligent, mobile, and terrain-adaptive system. The robot incorporates existing technologies in novel ways. The legs emulate the walking path of a human by an innovative modification of a crank-and-rocker mechanism. The body consists of two tripod frames connected by a turning mechanism. The two sets of three legs are mounted so as to allow the robot to walk with stability in its own footsteps. The computer uses a modular hardware design and distributed processing. Dual-port RAM is used to allow communication between a supervisory personal computer and seven microcontrollers. The microcontrollers provide low-level control for the motors and relieve the processing burden on the PC.

  15. Biologically inspired adaptive walking of a quadruped robot.

    PubMed

    Kimura, Hiroshi; Fukuoka, Yasuhiro; Cohen, Avis H

    2007-01-15

    We describe here the efforts to induce a quadruped robot to walk with medium-walking speed on irregular terrain based on biological concepts. We propose the necessary conditions for stable dynamic walking on irregular terrain in general, and we design the mechanical and the neural systems by comparing biological concepts with those necessary conditions described in physical terms. PD-controller at joints constructs the virtual spring-damper system as the viscoelasticity model of a muscle. The neural system model consists of a central pattern generator (CPG), reflexes and responses. We validate the effectiveness of the proposed neural system model control using the quadruped robots called 'Tekken1&2'. MPEG footage of experiments can be seen at http://www.kimura.is.uec.ac.jp. PMID:17148054

  16. Change in Action: How Infants Learn to Walk Down Slopes

    PubMed Central

    Gill, Simone V.; Adolph, Karen E.; Vereijken, Beatrix

    2009-01-01

    A critical aspect of perception-action coupling is the ability to modify ongoing actions in accordance with variations in the environment. Infants ability to modify their gait patterns to walk down shallow and steep slopes was examined at three nested time scales. Across sessions, a microgenetic training design showed rapid improvements after the first session in infants receiving concentrated practice walking down slopes and in infants in a control group who were tested only at the beginning and end of the study. Within sessions, analyses across easy and challenging slope angles showed that infants used a braking strategy to curb increases in walking speed across increasingly steeper slopes. Within trials, comparisons of infants gait modifications before and after stepping over the brink of the slopes showed that the braking strategy was planned prospectively. Findings illustrate how observing change in action provides important insights into the process of skill acquisition. PMID:19840044

  17. Physical activity and walking onset in infants with Down syndrome.

    PubMed

    Lloyd, Meghann; Burghardt, Amy; Ulrich, Dale A; Angulo-Barroso, Rosa

    2010-01-01

    Infants with Down syndrome (DS) are described as being less active and they also experience significant delays in motor development. It is hypothesized that early infant physical activity may be influential for the acquisition of independent walking. Physical activity was monitored longitudinally in 30 infants with DS starting at an average age of 10 months participating in a treadmill training intervention. Actiwatches were placed on infants' trunk and right ankle for a 24-hr period, every other month until walking onset. Data were analyzed to separate sedentary-to-light activity (low-act) and moderate-to-vigorous activity (high-act). Results showed that more leg high-act at an average age of 12 and 14 months is related to earlier onset of walking. It is recommended that early leg activity should be promoted in infants with DS. PMID:20147766

  18. Random walks on semantic networks can resemble optimal foraging.

    PubMed

    Abbott, Joshua T; Austerweil, Joseph L; Griffiths, Thomas L

    2015-07-01

    When people are asked to retrieve members of a category from memory, clusters of semantically related items tend to be retrieved together. A recent article by Hills, Jones, and Todd (2012) argued that this pattern reflects a process similar to optimal strategies for foraging for food in patchy spatial environments, with an individual making a strategic decision to switch away from a cluster of related information as it becomes depleted. We demonstrate that similar behavioral phenomena also emerge from a random walk on a semantic network derived from human word-association data. Random walks provide an alternative account of how people search their memories, postulating an undirected rather than a strategic search process. We show that results resembling optimal foraging are produced by random walks when related items are close together in the semantic network. These findings are reminiscent of arguments from the debate on mental imagery, showing how different processes can produce similar results when operating on different representations. PMID:25642588

  19. Single integrodifferential wave equation for a Lévy walk

    NASA Astrophysics Data System (ADS)

    Fedotov, Sergei

    2016-02-01

    We derive the single integrodifferential wave equation for the probability density function of the position of a classical one-dimensional Lévy walk with continuous sample paths. This equation involves a classical wave operator together with memory integrals describing the spatiotemporal coupling of the Lévy walk. It is valid at all times, not only in the long time limit, and it does not involve any large-scale approximations. It generalizes the well-known telegraph or Cattaneo equation for the persistent random walk with the exponential switching time distribution. Several non-Markovian cases are considered when the particle's velocity alternates at the gamma and power-law distributed random times. In the strong anomalous case we obtain the asymptotic solution to the integrodifferential wave equation. We implement the nonlinear reaction term of Kolmogorov-Petrovsky-Piskounov type into our equation and develop the theory of wave propagation in reaction-transport systems involving Lévy diffusion.

  20. Quantum walks on a circle with optomechanical systems

    NASA Astrophysics Data System (ADS)

    Moqadam, Jalil Khatibi; Portugal, Renato; de Oliveira, Marcos Cesar

    2015-10-01

    We propose an implementation of a quantum walk on a circle in an optomechanical system by encoding the walker on the phase space of a radiation field and the coin on a two-level state of a mechanical resonator. The dynamics of the system is obtained by applying Suzuki-Trotter decomposition. We numerically show that the system displays typical behaviors of quantum walks, namely the probability distribution evolves ballistically and the standard deviation of the phase distribution is linearly proportional to the number of steps. We also analyze the effects of decoherence by using the phase-damping channel on the coin space, showing the possibility to implement the quantum walk with present-day technology.

  1. Wilson loops in string duals of walking and flavored systems

    SciTech Connect

    Nunez, Carlos; Piai, Maurizio; Rago, Antonio

    2010-04-15

    We consider the vacuum expectation value of Wilson loop operators by studying the behavior of string probes in solutions of type-IIB string theory generated by N{sub c} D5-branes wrapped on an S{sup 2} internal manifold. In particular, we focus on solutions to the background equations that are dual to field theories with a walking gauge coupling as well as for flavored systems. We present in detail our walking solution and emphasize various general aspects of the procedure to study Wilson loops using string duals. We discuss the special features that the strings show when probing the region associated with the walking of the field-theory coupling.

  2. Walking in the 3-dimensional large N scalar model

    NASA Astrophysics Data System (ADS)

    Aoki, Sinya; Balog, Janos; Weisz, Peter

    2014-09-01

    The solvability of the three-dimensional O( N) scalar field theory in the large N limit makes it an ideal toy model exhibiting "walking" behavior, expected in some SU( N) gauge theories with a large number of fermion flavors. We study the model using lattice regularization and show that when the ratio of the particle mass to an effective 4-point coupling (with dimension mass) is small, the beta function associated to the running 4-point coupling is "walking". We also study lattice artifacts and finite size effects, and find that while the former can be sizable at realistic correlation length, the latter are under control already at lattice sizes a few (˜3) correlation lengths. We show the robustness of the walking phenomenon by showing that it can also be observed by studying physical observables such as the scattering phase shifts and the mass gap in finite volume.

  3. Structural characterization of ice polymorphs from self-avoiding walks

    NASA Astrophysics Data System (ADS)

    Herrero, Carlos P.

    2014-08-01

    Topological properties of crystalline ice structures are studied by means of self-avoiding walks on their H-bond networks. The number of self-avoiding walks, Cn, for eight ice polymorphs has been obtained by direct enumeration up to walk length n=27. This has allowed us to determine the ‘connective constant' or effective coordination number μ of these structures as the limit of the ratio Cn/Cn-1 for large n. This structure-dependent parameter μ is related with other topological characteristics of ice polymorphs, such as the mean and minimum ring size, or the topological density of network sites. A correlation between the connective constant and the configurational entropy of hydrogen-disordered ice structures is discussed.

  4. Gait Event Detection during Stair Walking Using a Rate Gyroscope

    PubMed Central

    Formento, Paola Catalfamo; Acevedo, Ruben; Ghoussayni, Salim; Ewins, David

    2014-01-01

    Gyroscopes have been proposed as sensors for ambulatory gait analysis and functional electrical stimulation systems. These applications often require detection of the initial contact (IC) of the foot with the floor and/or final contact or foot off (FO) from the floor during outdoor walking. Previous investigations have reported the use of a single gyroscope placed on the shank for detection of IC and FO on level ground and incline walking. This paper describes the evaluation of a gyroscope placed on the shank for determination of IC and FO in subjects ascending and descending a set of stairs. Performance was compared with a reference pressure measurement system. The absolute mean difference between the gyroscope and the reference was less than 45 ms for IC and better than 135 ms for FO for both activities. Detection success was over 93%. These results provide preliminary evidence supporting the use of a gyroscope for gait event detection when walking up and down stairs. PMID:24651724

  5. Superstatistical analysis and modelling of heterogeneous random walks

    NASA Astrophysics Data System (ADS)

    Metzner, Claus; Mark, Christoph; Steinwachs, Julian; Lautscham, Lena; Stadler, Franz; Fabry, Ben

    2015-06-01

    Stochastic time series are ubiquitous in nature. In particular, random walks with time-varying statistical properties are found in many scientific disciplines. Here we present a superstatistical approach to analyse and model such heterogeneous random walks. The time-dependent statistical parameters can be extracted from measured random walk trajectories with a Bayesian method of sequential inference. The distributions and correlations of these parameters reveal subtle features of the random process that are not captured by conventional measures, such as the mean-squared displacement or the step width distribution. We apply our new approach to migration trajectories of tumour cells in two and three dimensions, and demonstrate the superior ability of the superstatistical method to discriminate cell migration strategies in different environments. Finally, we show how the resulting insights can be used to design simple and meaningful models of the underlying random processes.

  6. Swarming bacteria migrate by Lévy Walk

    NASA Astrophysics Data System (ADS)

    Ariel, Gil; Rabani, Amit; Benisty, Sivan; Partridge, Jonathan D.; Harshey, Rasika M.; Be'Er, Avraham

    2015-09-01

    Individual swimming bacteria are known to bias their random trajectories in search of food and to optimize survival. The motion of bacteria within a swarm, wherein they migrate as a collective group over a solid surface, is fundamentally different as typical bacterial swarms show large-scale swirling and streaming motions involving millions to billions of cells. Here by tracking trajectories of fluorescently labelled individuals within such dense swarms, we find that the bacteria are performing super-diffusion, consistent with Lévy walks. Lévy walks are characterized by trajectories that have straight stretches for extended lengths whose variance is infinite. The evidence of super-diffusion consistent with Lévy walks in bacteria suggests that this strategy may have evolved considerably earlier than previously thought.

  7. Convergence of a random walk method for the Burgers equation

    SciTech Connect

    Roberts, S.

    1985-10-01

    In this paper we consider a random walk algorithm for the solution of Burgers' equation. The algorithm uses the method of fractional steps. The non-linear advection term of the equation is solved by advecting ''fluid'' particles in a velocity field induced by the particles. The diffusion term of the equation is approximated by adding an appropriate random perturbation to the positions of the particles. Though the algorithm is inefficient as a method for solving Burgers' equation, it does model a similar method, the random vortex method, which has been used extensively to solve the incompressible Navier-Stokes equations. The purpose of this paper is to demonstrate the strong convergence of our random walk method and so provide a model for the proof of convergence for more complex random walk algorithms; for instance, the random vortex method without boundaries.

  8. Characteristics of Walking Group Leaders as Compared to Walking Group Members in a Community-Based Study

    PubMed Central

    Wilcox, Sara; Forthofer, Melinda; Sharpe, Patricia A.; Hutto, Brent

    2015-01-01

    BACKGROUND Walking interventions delivered by lay leaders have been shown to be effective. Knowing the characteristics of individuals who volunteer to be group leaders in walking programs could facilitate more efficient and effective recruitment and training. METHODS Walking group leaders were recruited into a community-based program and formed walking groups from existing social networks. Leaders and members completed a survey, participated in physical measurements, and wore an accelerometer. Regression models (adjusting for group clustering and covariates) tested psychosocial and behavioral differences between leaders and members. RESULTS The sample included 296 adults (86% women, 66% African American). Leaders (n=60) were similar to members (n=236) with respect to most sociodemographic and health characteristics, but were significantly older and more likely to report arthritis and high cholesterol (p values < .05). Although leaders and members were similar in sedentary behavior and physical activity, leaders reported higher levels of exercise self-regulation, self-efficacy, and social support (p values < .01). Leaders also reported greater use of outdoor trails (p=.005) and other outdoor recreation areas (p=.003) for physical activity than members. CONCLUSION Although walking group leaders were no more active than members, leaders did display psychosocial characteristics and behaviors consistent with a greater readiness for change. PMID:26083073

  9. Walking Is Not Like Reaching: Evidence from Periodic Mechanical Perturbations

    PubMed Central

    Ahn, Jooeun; Hogan, Neville

    2012-01-01

    The control architecture underlying human reaching has been established, at least in broad outline. However, despite extensive research, the control architecture underlying human locomotion remains unclear. Some studies show evidence of high-level control focused on lower-limb trajectories; others suggest that nonlinear oscillators such as lower-level rhythmic central pattern generators (CPGs) play a significant role. To resolve this ambiguity, we reasoned that if a nonlinear oscillator contributes to locomotor control, human walking should exhibit dynamic entrainment to periodic mechanical perturbation; entrainment is a distinctive behavior of nonlinear oscillators. Here we present the first behavioral evidence that nonlinear neuro-mechanical oscillators contribute to the production of human walking, albeit weakly. As unimpaired human subjects walked at constant speed, we applied periodic torque pulses to the ankle at periods different from their preferred cadence. The gait period of 18 out of 19 subjects entrained to this mechanical perturbation, converging to match that of the perturbation. Significantly, entrainment occurred only if the perturbation period was close to subjects' preferred walking cadence: it exhibited a narrow basin of entrainment. Further, regardless of the phase within the walking cycle at which perturbation was initiated, subjects' gait synchronized or phase-locked with the mechanical perturbation at a phase of gait where it assisted propulsion. These results were affected neither by auditory feedback nor by a distractor task. However, the convergence to phase-locking was slow. These characteristics indicate that nonlinear neuro-mechanical oscillators make at most a modest contribution to human walking. Our results suggest that human locomotor control is not organized as in reaching to meet a predominantly kinematic specification, but is hierarchically organized with a semi-autonomous peripheral oscillator operating under episodic supervisory control. PMID:22479311

  10. Walking with wider steps increases stance phase gluteus medius activity

    PubMed Central

    Kubinski, Samantha N.; McQueen, Christina A.; Sittloh, Keir A.; Dean, Jesse C.

    2014-01-01

    Increases in step width have been reported for several clinical populations, including older adults and stroke survivors. These populations often also exhibit decreased hip abductor strength, suggesting that walking with wider steps may be an adaptive response in order to reduce the mechanical demands on the hip abductors. The purpose of this study was to quantify the relationship between step width and gluteus medius (GM) activity during walking. Fourteen young, uninjured adults walked on a treadmill at 1.25 m/s for four step width conditions (Normal, Narrow, Medium, and Wide) while step width and stance phase GM electromyographic (EMG) activity were quantified. We also measured hip abduction torque and GM activity during maximum voluntary isometric contractions (MVICs) at three hip angles (neutral, abducted 10, and abducted 20). During walking trials, GM activity was significantly (p<0.0001) influenced by step width; compared to Normal walking, GM activity was 47% higher with Wide steps and 24% lower with Narrow steps. We also observed a weak positive correlation (r=0.180.14) between step width and GM activity during Normal walking, as GM activity was higher with wider steps. These results cannot be attributed to changes in GM conformation under the recording electrode, as GM activity was not influenced by hip angle during MVICs. The increased GM activity with wider steps does not support the proposal that increasing step width would be a beneficial adaptation to weakened hip abductors. A likely alternative explanation is that increased step width is a response to decreased gait balance. PMID:25300241

  11. Walking stability during cell phone use in healthy adults.

    PubMed

    Kao, Pei-Chun; Higginson, Christopher I; Seymour, Kelly; Kamerdze, Morgan; Higginson, Jill S

    2015-05-01

    The number of falls and/or accidental injuries associated with cellular phone use during walking is growing rapidly. Understanding the effects of concurrent cell phone use on human gait may help develop safety guidelines for pedestrians. It was shown previously that older adults had more pronounced dual-task interferences than younger adults when concurrent cognitive task required visual information processing. Thus, cell phone use might have greater impact on walking stability in older than in younger adults. This study examined gait stability and variability during a cell phone dialing task (phone) and two classic cognitive tasks, the Paced Auditory Serial Addition Test (PASAT) and Symbol Digit Modalities Test (SDMT). Nine older and seven younger healthy adults walked on a treadmill at four different conditions: walking only, PASAT, phone, and SDMT. We computed short-term local divergence exponent (LDE) of the trunk motion (local stability), dynamic margins of stability (MOS), step spatiotemporal measures, and kinematic variability. Older and younger adults had similar values of short-term LDE during all conditions, indicating that local stability was not affected by the dual-task. Compared to walking only, older and younger adults walked with significantly greater average mediolateral MOS during phone and SDMT conditions but significantly less ankle angle variability during all dual-tasks and less knee angle variability during PASAT. The current findings demonstrate that healthy adults may try to control foot placement and joint kinematics during cell phone use or another cognitive task with a visual component to ensure sufficient dynamic margins of stability and maintain local stability. PMID:25890490

  12. Running for Exercise Mitigates Age-Related Deterioration of Walking Economy

    PubMed Central

    Ortega, Justus D.; Beck, Owen N.; Roby, Jaclyn M.; Turney, Aria L.; Kram, Rodger

    2014-01-01

    Introduction Impaired walking performance is a key predictor of morbidity among older adults. A distinctive characteristic of impaired walking performance among older adults is a greater metabolic cost (worse economy) compared to young adults. However, older adults who consistently run have been shown to retain a similar running economy as young runners. Unfortunately, those running studies did not measure the metabolic cost of walking. Thus, it is unclear if running exercise can prevent the deterioration of walking economy. Purpose To determine if and how regular walking vs. running exercise affects the economy of locomotion in older adults. Methods 15 older adults (693 years) who walk ?30 min, 3x/week for exercise, walkers and 15 older adults (695 years) who run ?30 min, 3x/week, runners walked on a force-instrumented treadmill at three speeds (0.75, 1.25, and 1.75 m/s). We determined walking economy using expired gas analysis and walking mechanics via ground reaction forces during the last 2 minutes of each 5 minute trial. We compared walking economy between the two groups and to non-aerobically trained young and older adults from a prior study. Results Older runners had a 710% better walking economy than older walkers over the range of speeds tested (p?=?.016) and had walking economy similar to young sedentary adults over a similar range of speeds (p?=?.237). We found no substantial biomechanical differences between older walkers and runners. In contrast to older runners, older walkers had similar walking economy as older sedentary adults (p?=?.461) and ?26% worse walking economy than young adults (p<.0001). Conclusion Running mitigates the age-related deterioration of walking economy whereas walking for exercise appears to have minimal effect on the age-related deterioration in walking economy. PMID:25411850

  13. Homogeneous Open Quantum Random Walks on a Lattice

    NASA Astrophysics Data System (ADS)

    Carbone, Raffaella; Pautrat, Yan

    2015-09-01

    We study open quantum random walks (OQRWs) for which the underlying graph is a lattice, and the generators of the walk are homogeneous in space. Using the results recently obtained in Carbone and Pautrat (Ann Henri Poincar, 2015), we study the quantum trajectory associated with the OQRW, which is described by a position process and a state process. We obtain a central limit theorem and a large deviation principle for the position process. We study in detail the case of homogeneous OQRWs on the lattice , with internal space.

  14. Continuous-Time Random Walks, Fractional Calculus and Stochastic Integrals

    NASA Astrophysics Data System (ADS)

    Scalas, E.; Germano, G.; Politi, M.; Schilling, R. L.

    2009-04-01

    Continuous-time random walks are pure-jump processes with several applications in physics, but also in insurance, finance and economics. Based on heuristic considerations, a definition is given for the stochastic integral driven by continuous-time random walks. The martingale properties of the integral are investigated. It is shown how the definition can be used to easily compute the stochastic integral by means of Monte Carlo simulations. The relationship with fractional calculus is discussed. Link to related preprint: http://arxiv.org/abs/0802.3769

  15. Experimental realization of generalized qubit measurements based on quantum walks

    NASA Astrophysics Data System (ADS)

    Zhao, Yuan-yuan; Yu, Neng-kun; Kurzy?ski, Pawe?; Xiang, Guo-yong; Li, Chuan-Feng; Guo, Guang-Can

    2015-04-01

    We report an experimental implementation of a single-qubit generalized measurement scenario, the positive-operator valued measure (POVM), based on a quantum walk model. The qubit is encoded in a single-photon polarization. The photon performs a quantum walk on an array of optical elements, where the polarization-dependent translation is performed via birefringent beam displacers and a change of the polarization is implemented with the help of wave plates. We implement: (i) trine POVM, i.e., the POVM elements uniformly distributed on an equatorial plane of the Bloch sphere; (ii) symmetric-informationally-complete (SIC) POVM; and (iii) unambiguous discrimination of two nonorthogonal qubit states.

  16. Quadriceps oxygenation changes during walking and running on a treadmill

    NASA Astrophysics Data System (ADS)

    Quaresima, Valentina; Pizzi, Assunta; De Blasi, Roberto A.; Ferrari, Adriano; de Angelis, Marco; Ferrari, Marco

    1995-04-01

    Vastus lateralis muscle oxygenation was investigated on volunteers as well as muscular dystrophy patients during a walking test, and on volunteers during a free running by a continuous wave near infrared instrument. The data were analyzed using an oxygenation index independent on pathlength changes. Walking did not significantly affect the oxygenation of volunteers and patients. A relative deoxygenation was found only during free running indicating an unbalance between oxygen supply and tissue oxygen extraction. Preliminary measurements of exercising muscle oxygen saturation were performed by a 110 MHz frequency-domain, multisource instrument.

  17. Faster quantum walk search on a weighted graph

    NASA Astrophysics Data System (ADS)

    Wong, Thomas G.

    2015-09-01

    A randomly walking quantum particle evolving by Schrdinger's equation searches for a unique marked vertex on the "simplex of complete graphs" in time ? (N3 /4) . We give a weighted version of this graph that preserves vertex transitivity, and we show that the time to search on it can be reduced to nearly ? (?{N }) . To prove this, we introduce two extensions to degenerate perturbation theory: an adjustment that distinguishes the weights of the edges and a method to determine how precisely the jumping rate of the quantum walk must be chosen.

  18. An Uncontrolled Walking Toy That Cannot Stand Still

    NASA Astrophysics Data System (ADS)

    Coleman, Michael J.; Ruina, Andy

    1998-04-01

    We built a simple two-leg toy that can walk stably with no control system. It walks downhill powered only by gravity. It seems to be the first McGeer-like passive-dynamic walker that is statically unstable in all standing positions, yet is stable in motion. It is one of a few known mechanical devices that are stable near a statically unstable configuration but do not depend on spinning parts. Its design is loosely based on simulations which do not predict its observed stability. Its motion highlights the possible role of uncontrolled nonholonomic mechanics in balance.

  19. Mechanics and energetics of level walking with powered ankle exoskeletons.

    PubMed

    Sawicki, Gregory S; Ferris, Daniel P

    2008-05-01

    Robotic lower limb exoskeletons that can alter joint mechanical power output are novel tools for studying the relationship between the mechanics and energetics of human locomotion. We built pneumatically powered ankle exoskeletons controlled by the user's own soleus electromyography (i.e. proportional myoelectric control) to determine whether mechanical assistance at the ankle joint could reduce the metabolic cost of level, steady-speed human walking. We hypothesized that subjects would reduce their net metabolic power in proportion to the average positive mechanical power delivered by the bilateral ankle exoskeletons. Nine healthy individuals completed three 30 min sessions walking at 1.25 m s(-1) while wearing the exoskeletons. Over the three sessions, subjects' net metabolic energy expenditure during powered walking progressed from +7% to -10% of that during unpowered walking. With practice, subjects significantly reduced soleus muscle activity (by approximately 28% root mean square EMG, P<0.0001) and negative exoskeleton mechanical power (-0.09 W kg(-1) at the beginning of session 1 and -0.03 W kg(-1) at the end of session 3; P=0.005). Ankle joint kinematics returned to similar patterns to those observed during unpowered walking. At the end of the third session, the powered exoskeletons delivered approximately 63% of the average ankle joint positive mechanical power and approximately 22% of the total positive mechanical power generated by all of the joints summed (ankle, knee and hip) during unpowered walking. Decreases in total joint positive mechanical power due to powered ankle assistance ( approximately 22%) were not proportional to reductions in net metabolic power ( approximately 10%). The ;apparent efficiency' of the ankle joint muscle-tendon system during human walking ( approximately 0.61) was much greater than reported values of the ;muscular efficiency' of positive mechanical work for human muscle ( approximately 0.10-0.34). High ankle joint ;apparent efficiency' suggests that recoiling Achilles' tendon contributes a significant amount of ankle joint positive power during the push-off phase of walking in humans. PMID:18424674

  20. Strategies for Walking on a Laterally Oscillating Treadmill

    NASA Technical Reports Server (NTRS)

    Peters, Brian T.; Brady, Rachel A.; Bloomberg, Jacob, J.

    2008-01-01

    Most people use a variety of gait patterns each day. These changes can come about by voluntary actions, such as a decision to walk faster when running late. They can also be a result of both conscious and subconscious changes made to account for variation in the environmental conditions. Many factors can play a role in determining the optimal gait patterns, but the relative importance of each could vary between subjects. A goal of this study was to investigate whether subjects used consistent gait strategies when walking on an unstable support surface.

  1. Post and a random-walk search mode

    NASA Technical Reports Server (NTRS)

    Martin, J. A.

    1984-01-01

    Multidisciplinary analysis often requires optimization of nonlinear systems that are subject to constraints. Trajectory optimization is one example of this situation. The Program to Optimize Simulated Trajectories (POST) was used successfully for a number of problems. The purpose is to describe POST and a new optimization approach that has been incorporated into it. Typical uses of POST will also be illustrated. The projected-gradient approach to optimization is the preferred option in POST and is discussed. A new approach to optimization, the random-walk approach, is described, and results with the random-walk approach are presented.

  2. Variations in Community Prevalence and Determinants of Recreational and Utilitarian Walking in Older Age

    PubMed Central

    Procter-Gray, Elizabeth; Leveille, Suzanne G.; Hannan, Marian T.; Cheng, Jie; Kane, Kevin; Li, Wenjun

    2015-01-01

    Background. Regular walking is critical to maintaining health in older age. We examined influences of individual and community factors on walking habits in older adults. Methods. We analyzed walking habits among participants of a prospective cohort study of 745 community-dwelling men and women, mainly aged 70 years or older. We estimated community variations in utilitarian and recreational walking, and examined whether the variations were attributable to community differences in individual and environmental factors. Results. Prevalence of recreational walking was relatively uniform while prevalence of utilitarian walking varied across the 16 communities in the study area. Both types of walking were associated with individual health and physical abilities. However, utilitarian walking was also strongly associated with several measures of neighborhood socioeconomic status and access to amenities while recreational walking was not. Conclusions. Utilitarian walking is strongly influenced by neighborhood environment, but intrinsic factors may be more important for recreational walking. Communities with the highest overall walking prevalence were those with the most utilitarian walkers. Public health promotion of regular walking should take this into account. PMID:26339507

  3. Using Actual and Imagined Walking Related Desynchronization Features in a BCI.

    PubMed

    Severens, Marianne; Perusquia-Hernandez, Monica; Nienhuis, Bart; Farquhar, Jason; Duysens, Jacques

    2015-09-01

    Recently, brain-computer interface (BCI) research has extended to investigate its possible use in motor rehabilitation. Most of these investigations have focused on the upper body. Only few studies consider gait because of the difficulty of recording EEG during gross movements. However, for stroke patients the rehabilitation of gait is of crucial importance. Therefore, this study investigates if a BCI can be based on walking related desynchronization features. Furthermore, the influence of complexity of the walking movements on the classification performance is investigated. Two BCI experiments were conducted in which healthy subjects performed a cued walking task, a more complex walking task (backward or adaptive walking), and imagination of the same tasks. EEG data during these tasks was classified into walking and no-walking. The results from both experiments show that despite the automaticity of walking and recording difficulties, brain signals related to walking could be classified rapidly and reliably. Classification performance was higher for actual walking movements than for imagined walking movements. There was no significant increase in classification performance for both the backward and adaptive walking tasks compared with the cued walking tasks. These results are promising for developing a BCI for the rehabilitation of gait. PMID:26353236

  4. Walking to Olympus: An EVA Chronology

    NASA Technical Reports Server (NTRS)

    Portree, David S. F.; Trevino, Robert C.

    1997-01-01

    Spacewalkers enjoy a view of Earth once reserved for Apollo, Zeus, and other denizens of Mt. Olympus. During humanity's first extravehicular activity (EVA), Alexei Leonov floated above Gibraltar, the rock ancient seafarers saw as the gateway to the great unknown Atlantic. The symbolism was clear, Leonov stepped past a new Gibraltar when he stepped into space. More than 32 years and 154 EVAs later, Jerry Linenger conducted an EVA with Vladimir Tsibliyev as part of International Space Station Phase 1. They floated together above Gibraltar. Today the symbolism has new meaning: humanity is starting to think of stepping out of Earth orbit, space travel's new Gibraltar, and perhaps obtaining a new olympian view, a close-up look at Olympus Mons on Mars. Walking to Olympus: An EVA Chronology chronicles the 154 EVAs conducted from March 1965 to April 1997. It is intended to make clear the crucial role played by EVA in the history of spaceflight, as well as to chronicle the large body of EVA "lessons learned." Russia and the U.S. define EVA differently. Russian cosmonauts are said to perform EVA any time they are in vacuum in a space suit. A U.S. astronaut must have at least his head outside his spacecraft before he is said to perform an EVA. The difference is based in differing spacecraft design philoso- phies. Russian and Soviet spacecraft have always had a specialized airlock through which the EVA cosmonaut egressed, leaving the main habitable volume of the spacecraft pressurized. The U.S. Gemini and Apollo vehicles, on the other hand, depressurized their entire habitable volume for egress. In this document, we apply the Russian definition to Russian EVAS, and the U.S. definition to U.S. EVAS. Thus, for example, Gemini 4 Command Pilot James McDivitt does not share the honor of being first American spacewalker with Ed White, even though he was suited and in vacuum when White stepped out into space. Non-EVA spaceflights are listed in the chronology to provide context and to display the large num- ber of flights in which EVA played a role. This approach also makes apparent significant EVA gaps, for example, the U.S. gap between 1985 and 1991 following the Challenger accident. This NASA History Monograph is an edited extract from an extensive EVA Chronology and Reference Book being produced by the EVA Project Office, NASA Johnson Space Center, Houston, Texas. The larger work will be published as part of the NASA Formal Series in 1998. The authors gratefully acknowledge the assistance rendered by Max Ary, Ashot Bakunts, Gert-Jan Bartelds, Frank Cepollina, Andrew Chaikin, Phillip Clark, Richard Fullerton, Steven Glenn, Linda Godwin, Jennifer Green, Greg Harris, Clifford Hess, Jeffrey Hoffman, David Homan, Steven Hopkins, Nicholas Johnson, Eric Jones, Neville Kidger, Joseph Kosmo, Alexei Lebedev, Mark Lee, James LeBlanc, Dmitri Leshchenskii, Jerry Linenger, Igor Lissov, James McBarron, Clay McCullough, Joseph McMann, Story Musgrave, Dennis Newkirk, James Oberg, Joel Powell, Lee Saegesser, Andy Salmon, Glen Swanson, Joseph Tatarewicz, Kathy Thornton, Chris Vandenberg, Charles Vick, Bert Vis, David Woods, Mike Wright, John Young, and Keith Zimmerman. Special thanks to Laurie Buchanan, John Charles, Janet Kovacevich, Joseph Loftus, Sue McDonald, Martha Munies, Colleen Rapp, and Jerry Ross. Any errors remain the responsibility of the authors.

  5. A randomized trial of functional electrical stimulation for walking in incomplete spinal cord injury: Effects on walking competency

    PubMed Central

    Kapadia, Naaz; Masani, Kei; Catharine Craven, B.; Giangregorio, Lora M.; Hitzig, Sander L.; Richards, Kieva; Popovic, Milos R.

    2014-01-01

    Background Multi-channel surface functional electrical stimulation (FES) for walking has been used to improve voluntary walking and balance in individuals with spinal cord injury (SCI). Objective To investigate short- and long-term benefits of 16 weeks of thrice-weekly FES-assisted walking program, while ambulating on a body weight support treadmill and harness system, versus a non-FES exercise program, on improvements in gait and balance in individuals with chronic incomplete traumatic SCI, in a randomized controlled trial design. Methods Individuals with traumatic and chronic (?18 months) motor incomplete SCI (level C2 to T12, American Spinal Cord Injury Association Impairment Scale C or D) were recruited from an outpatient SCI rehabilitation hospital, and randomized to FES-assisted walking therapy (intervention group) or aerobic and resistance training program (control group). Outcomes were assessed at baseline, and after 4, 6, and 12 months. Gait, balance, spasticity, and functional measures were collected. Results Spinal cord independence measure (SCIM) mobility sub-score improved over time in the intervention group compared with the control group (baseline/12 months: 17.27/21.33 vs. 19.09/17.36, respectively). On all other outcome measures the intervention and control groups had similar improvements. Irrespective of group allocation walking speed, endurance, and balance during ambulation all improved upon completion of therapy, and majority of participants retained these gains at long-term follow-ups. Conclusions Task-oriented training improves walking ability in individuals with incomplete SCI, even in the chronic stage. Further randomized controlled trials, involving a large number of participants are needed, to verify if FES-assisted treadmill training is superior to aerobic and strength training. PMID:25229735

  6. Effects of a 6-month exercise program pilot study on walking economy, peak physiological characteristics, and walking performance in patients with peripheral arterial disease

    PubMed Central

    Crowther, Robert G; Leicht, Anthony S; Spinks, Warwick L; Sangla, Kunwarjit; Quigley, Frank; Golledge, Jonathan

    2012-01-01

    The purpose of this study was to examine the effects of a 6-month exercise program on submaximal walking economy in individuals with peripheral arterial disease and intermittent claudication (PAD-IC). Participants (n = 16) were randomly allocated to either a control PAD-IC group (CPAD-IC, n = 6) which received standard medical therapy, or a treatment PAD-IC group (TPAD-IC; n = 10) which took part in a supervised exercise program. During a graded treadmill test, physiological responses, including oxygen consumption, were assessed to calculate walking economy during submaximal and maximal walking performance. Differences between groups at baseline and post-intervention were analyzed via KruskalWallis tests. At baseline, CPAD-IC and TPAD-IC groups demonstrated similar walking performance and physiological responses. Postintervention, TPAD-IC patients demonstrated significantly lower oxygen consumption during the graded exercise test, and greater maximal walking performance compared to CPAD-IC. These preliminary results indicate that 6 months of regular exercise improves both submaximal walking economy and maximal walking performance, without significant changes in maximal walking economy. Enhanced walking economy may contribute to physiological efficiency, which in turn may improve walking performance as demonstrated by PAD-IC patients following regular exercise programs. PMID:22566743

  7. On your feet: protocol for a randomized controlled trial to compare the effects of pole walking and regular walking on physical and psychosocial health in older adults

    PubMed Central

    2014-01-01

    Background Physical activity is associated with better physical and mental health in older adults. Pole walking is a form of walking which may have additional health benefits in older adults, because of the addition of hand held poles, and consequent upper limb involvement. However, few studies have examined the potential additional effects of pole walking on physical and psychosocial health in older adults compared with walking. The aim of this study is to compare the effect of a pole walking program with the effects of a walking program, on physical and psychosocial wellbeing, in older adults in assisted living facilities. Methods/Design Sixty men and women from assisted living communities over 65years will be recruited from senior retirement facilities and randomized into a group based, pole walking program, or walking program. The pole walking group will use the Exerstrider method of pole walking. Total duration of the programs is 12weeks, with three sessions per week, building from 20minute to 30minute sessions. The primary outcome is physical function, as measured by items from the Seniors Fitness Test and hand grip strength. Secondary outcomes include, physical activity levels, sedentary behaviour, joint pain, and quality of life. All outcomes will be assessed before and after the programs, using valid and reliable measures. Discussion The study will add to the evidence base for the effects of pole walking, compared with walking, on physical and psychosocial health and physical function, in healthy older adults. This will improve understanding about the feasibility of pole walking programs and its specific benefits in this population. Trial registration Australian New Zealand Clinical Trials Registry ACTRN12612001127897. PMID:24742126

  8. The Role of Walkers Needs and Expectations in Supporting Maintenance of Attendance at Walking Groups: A Longitudinal Multi-Perspective Study of Walkers and Walk Group Leaders

    PubMed Central

    Kassavou, Aikaterini; Turner, Andrew; French, David P.

    2015-01-01

    Background There is good evidence that when peoples needs and expectations regarding behaviour change are met, they are satisfied with that change, and maintain those changes. Despite this, there is a dearth of research on needs and expectations of walkers when initially attending walking groups and whether and how these needs and expectations have been satisfied after a period of attendance. Equally, there is an absence of research on how people who lead these groups understand walkers needs and walk leaders actions to address them. The present study was aimed at addressing both of these gaps in the research. Methods Two preliminary thematic analyses were conducted on face-to-face interviews with (a) eight walkers when they joined walking groups, five of whom were interviewed three months later, and (b) eight walk leaders. A multi-perspective analysis building upon these preliminary analyses identified similarities and differences within the themes that emerged from the interviews with walkers and walk leaders. Results Walkers indicated that their main needs and expectations when joining walking groups were achieving long-term social and health benefits. At the follow up interviews, walkers indicated that satisfaction with meeting similar others within the groups was the main reason for continued attendance. Their main source of dissatisfaction was not feeling integrated in the existing walking groups. Walk leaders often acknowledged the same reasons for walkers joining and maintaining attendance at walking. However, they tended to attribute dissatisfaction and drop out to uncontrollable environmental factors and/or walkers personalities. Walk leaders reported a lack of efficacy to effectively address walkers needs. Conclusions Interventions to increase retention of walkers should train walk leaders with the skills to help them modify the underlying psychological factors affecting walkers maintenance at walking groups. This should result in greater retention of walkers in walking groups, thereby allowing walkers to receive the long-term social and health benefits of participation in these groups. PMID:25774527

  9. Optimizing the 6-Min Walk Test as a Measure of Exercise Capacity in COPD

    PubMed Central

    Chandra, Divay; Wise, Robert A.; Kulkarni, Hrishikesh S.; Benzo, Roberto P.; Criner, Gerard; Make, Barry; Slivka, William A.; Ries, Andrew L.; Reilly, John J.; Martinez, Fernando J.

    2012-01-01

    Background: It is uncertain whether the effort and expense of performing a second walk for the 6-min walk test improves test performance. Hence, we attempted to quantify the improvement in 6-min walk distance if an additional walk were to be performed. Methods: We studied patients consecutively enrolled into the National Emphysema Treatment Trial who prior to randomization and after 6 to 10 weeks of pulmonary rehabilitation performed two 6-min walks on consecutive days (N = 396). Patients also performed two 6-min walks at 6-month follow-up after randomization to lung volume reduction surgery (n = 74) or optimal medical therapy (n = 64). We compared change in the first walk distance to change in the second, average-of-two, and best-of-two walk distances. Results: Compared with the change in the first walk distance, change in the average-of-two and best-of-two walk distances had better validity and precision. Specifically, 6 months after randomization to lung volume reduction surgery, changes in the average-of-two (r = 0.66 vs r = 0.58, P = .01) and best-of-two walk distances (r = 0.67 vs r = 0.58, P = .04) better correlated with the change in maximal exercise capacity (ie, better validity). Additionally, the variance of change was 14% to 25% less for the average-of-two walk distances and 14% to 33% less for the best-of-two walk distances than the variance of change in the single walk distance, indicating better precision. Conclusions: Adding a second walk to the 6-min walk test significantly improves its performance in measuring response to a therapeutic intervention, improves the validity of COPD clinical trials, and would result in a 14% to 33% reduction in sample size requirements. Hence, it should be strongly considered by clinicians and researchers as an outcome measure for therapeutic interventions in patients with COPD. PMID:23364913

  10. Generalized Levy-walk model for DNA nucleotide sequences

    NASA Technical Reports Server (NTRS)

    Buldyrev, S. V.; Goldberger, A. L.; Havlin, S.; Simons, M.; Stanley, H. E.

    1993-01-01

    We propose a generalized Levy walk to model fractal landscapes observed in noncoding DNA sequences. We find that this model provides a very close approximation to the empirical data and explains a number of statistical properties of genomic DNA sequences such as the distribution of strand-biased regions (those with an excess of one type of nucleotide) as well as local changes in the slope of the correlation exponent alpha. The generalized Levy-walk model simultaneously accounts for the long-range correlations in noncoding DNA sequences and for the apparently paradoxical finding of long subregions of biased random walks (length lj) within these correlated sequences. In the generalized Levy-walk model, the lj are chosen from a power-law distribution P(lj) varies as lj(-mu). The correlation exponent alpha is related to mu through alpha = 2-mu/2 if 2 < mu < 3. The model is consistent with the finding of "repetitive elements" of variable length interspersed within noncoding DNA.

  11. I-WALK: An Innovative Approach to Community Walkability

    ERIC Educational Resources Information Center

    Seeger, Christopher J.; Lillehoj, Catherine J.; Jensen, Alan D.; Wilson, Suzy; Levinson, Lydia R.

    2014-01-01

    One way of combating rising obesity rates and decreasing physical activity levels among children is to promote active transportation to and from schools. The award-winning I-WALK program provides a comprehensive framework for addressing community walkability and related infrastructure. The program uses a unique and innovative methodology that

  12. Protein localization prediction using random walks on graphs

    PubMed Central

    2013-01-01

    Background Understanding the localization of proteins in cells is vital to characterizing their functions and possible interactions. As a result, identifying the (sub)cellular compartment within which a protein is located becomes an important problem in protein classification. This classification issue thus involves predicting labels in a dataset with a limited number of labeled data points available. By utilizing a graph representation of protein data, random walk techniques have performed well in sequence classification and functional prediction; however, this method has not yet been applied to protein localization. Accordingly, we propose a novel classifier in the site prediction of proteins based on random walks on a graph. Results We propose a graph theory model for predicting protein localization using data generated in yeast and gram-negative (Gneg) bacteria. We tested the performance of our classifier on the two datasets, optimizing the model training parameters by varying the laziness values and the number of steps taken during the random walk. Using 10-fold cross-validation, we achieved an accuracy of above 61% for yeast data and about 93% for gram-negative bacteria. Conclusions This study presents a new classifier derived from the random walk technique and applies this classifier to investigate the cellular localization of proteins. The prediction accuracy and additional validation demonstrate an improvement over previous methods, such as support vector machine (SVM)-based classifiers. PMID:23815126

  13. Kinematic and stability motion limits for a hexapod walking machine

    NASA Astrophysics Data System (ADS)

    Dunton, Elizabeth M.

    1995-03-01

    The major problem addressed by this research is to investigate and implement the basic concepts necessary to lay the groundwork for efficient forms of motion planning, motion control, and gait algorithms with respect to hexapod walking machines. Specifically, the approach taken was to develop and implement the concepts of a stability margin and a joint space motion margin on an object-oriented representation of the Aquarobot. The model was generated in Franz Common Lisp and simulated via Allegro Common Windows. A method by which distance computations can be calculated and applied to the center of mass and triangular support pattern of a walking machine to determine the stability margin is introduced. Inverse kinematics and joint limits are utilized to ascertain the joint space motion margin of the model. Response to impending instability and the effect when a joint hits or approaches a joint kinematic limit on the motion of the hexapod walking machine by stopping the model is also addressed. The results are as follows: the concepts of the joint space motion margin and the stability margin can be successfully implemented on a kinematic model and graphical simulation of a hexapod walking machine. These concepts contribute to future work in the area of more efficient free gait algorithms, specifically asynchronous gait algorithms.

  14. Change in Smoking, Diet, and Walking for Exercise in Blacks

    ERIC Educational Resources Information Center

    Berg, Carla J.; Thomas, Janet L.; An, Lawrence C.; Guo, Hongfei; Collins, Tracie; Okuyemi, Kolawole S.; Ahluwalia, Jasjit S.

    2012-01-01

    Positive changes in one health behavior may be accompanied by other constructive health behavior changes. Thus, the authors investigated the association of smoking reduction and cessation to changes in fruit and vegetable (FV) intake and engaging in walking for exercise. This study included 539 Black light smokers ([less than or equal to]10

  15. Length of adaptive walk on uncorrelated and correlated fitness landscapes.

    PubMed

    Seetharaman, Sarada; Jain, Kavita

    2014-09-01

    We consider the adaptation dynamics of an asexual population that walks uphill on a rugged fitness landscape which is endowed with a large number of local fitness peaks. We work in a parameter regime where only those mutants that are a single mutation away are accessible, as a result of which the population eventually gets trapped at a local fitness maximum and the adaptive walk terminates. We study how the number of adaptive steps taken by the population before reaching a local fitness peak depends on the initial fitness of the population, the extreme value distribution of the beneficial mutations, and correlations among the fitnesses. Assuming that the relative fitness difference between successive steps is small, we analytically calculate the average walk length for both uncorrelated and correlated fitnesses in all extreme value domains for a given initial fitness. We present numerical results for the model where the fitness differences can be large and find that the walk length behavior differs from that in the former model in the Frchet domain of extreme value theory. We also discuss the relevance of our results to microbial experiments. PMID:25314469

  16. Solving the accuracy-diversity dilemma via directed random walks.

    PubMed

    Liu, Jian-Guo; Shi, Kerui; Guo, Qiang

    2012-01-01

    Random walks have been successfully used to measure user or object similarities in collaborative filtering (CF) recommender systems, which is of high accuracy but low diversity. A key challenge of a CF system is that the reliably accurate results are obtained with the help of peers' recommendation, but the most useful individual recommendations are hard to be found among diverse niche objects. In this paper we investigate the direction effect of the random walk on user similarity measurements and find that the user similarity, calculated by directed random walks, is reverse to the initial node's degree. Since the ratio of small-degree users to large-degree users is very large in real data sets, the large-degree users' selections are recommended extensively by traditional CF algorithms. By tuning the user similarity direction from neighbors to the target user, we introduce a new algorithm specifically to address the challenge of diversity of CF and show how it can be used to solve the accuracy-diversity dilemma. Without relying on any context-specific information, we are able to obtain accurate and diverse recommendations, which outperforms the state-of-the-art CF methods. This work suggests that the random-walk direction is an important factor to improve the personalized recommendation performance. PMID:22400636

  17. Solving the accuracy-diversity dilemma via directed random walks

    NASA Astrophysics Data System (ADS)

    Liu, Jian-Guo; Shi, Kerui; Guo, Qiang

    2012-01-01

    Random walks have been successfully used to measure user or object similarities in collaborative filtering (CF) recommender systems, which is of high accuracy but low diversity. A key challenge of a CF system is that the reliably accurate results are obtained with the help of peers' recommendation, but the most useful individual recommendations are hard to be found among diverse niche objects. In this paper we investigate the direction effect of the random walk on user similarity measurements and find that the user similarity, calculated by directed random walks, is reverse to the initial node's degree. Since the ratio of small-degree users to large-degree users is very large in real data sets, the large-degree users' selections are recommended extensively by traditional CF algorithms. By tuning the user similarity direction from neighbors to the target user, we introduce a new algorithm specifically to address the challenge of diversity of CF and show how it can be used to solve the accuracy-diversity dilemma. Without relying on any context-specific information, we are able to obtain accurate and diverse recommendations, which outperforms the state-of-the-art CF methods. This work suggests that the random-walk direction is an important factor to improve the personalized recommendation performance.

  18. Walking On Air - Duration: 3 minutes, 55 seconds.

    NASA Video Gallery

    This video features a series of time lapse sequences photographed by the Expedition 30 crew aboard the International Space Station. Set to the song “Walking in the Air,” by Howard Blake, the v...

  19. Characteristics associated with US Walk to School programs

    PubMed Central

    Ward, Dianne S; Linnan, Laura; Vaughn, Amber; Neelon, Brian; Martin, Sarah L; Fulton, Janet E

    2007-01-01

    Participation in Walk to School (WTS) programs has grown substantially in the US since its inception; however, no attempt has been made to systematically describe program use or factors associated with implementation of environment/policy changes. Describe the characteristics of schools' WTS programs by level of implementation. Representatives from 450 schools from 42 states completed a survey about their WTS program's infrastructure and activities, and perceived impact on walking to school. Level of implementation was determined from a single question to which respondents reported participation in WTS Day only (low), WTS Day and additional programs (medium), or making policy/environmental change (high). The final model showed number of community groups involved was positively associated with higher level of implementation (OR = 1.78, 95%CI = 1.44, 2.18), as was funding (OR = 1.56, 95%CI = 1.26, 1.92), years of participation (OR = 1.44, 95% CI = 1.23, 1.70), and use of a walkability assessment (OR = 3.22, 95%CI = 1.84, 5.64). Implementation level was modestly associated with increased walking (r = 0.18). Strong community involvement, some funding, repeat participation, and environmental audits are associated with progms that adopt environmental/policy change, and seem to facilitate walking to school. PMID:18093327

  20. Predictive Simulation Generates Human Adaptations during Loaded and Inclined Walking

    PubMed Central

    Hicks, Jennifer L.; Delp, Scott L.

    2015-01-01

    Predictive simulation is a powerful approach for analyzing human locomotion. Unlike techniques that track experimental data, predictive simulations synthesize gaits by minimizing a high-level objective such as metabolic energy expenditure while satisfying task requirements like achieving a target velocity. The fidelity of predictive gait simulations has only been systematically evaluated for locomotion data on flat ground. In this study, we construct a predictive simulation framework based on energy minimization and use it to generate normal walking, along with walking with a range of carried loads and up a range of inclines. The simulation is muscle-driven and includes controllers based on muscle force and stretch reflexes and contact state of the legs. We demonstrate how human-like locomotor strategies emerge from adapting the model to a range of environmental changes. Our simulation dynamics not only show good agreement with experimental data for normal walking on flat ground (92% of joint angle trajectories and 78% of joint torque trajectories lie within 1 standard deviation of experimental data), but also reproduce many of the salient changes in joint angles, joint moments, muscle coordination, and metabolic energy expenditure observed in experimental studies of loaded and inclined walking. PMID:25830913