Sample records for walking

  1. Walking abnormalities

    MedlinePLUS

    ... keep the foot in the right position for standing and walking. A physical therapist can supply these ... keep the foot in the right position for standing and walking. A physical therapist can supply these ...

  2. Lévy 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 Lévy-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 Lévy walks, surveys their existing applications, including latest advances, and outlines further perspectives.

  3. Lévy walks

    E-print Network

    V. Zaburdaev; S. Denisov; J. Klafter

    2015-01-23

    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 L\\'{e}vy 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, bio-physics, and behavioral science demonstrate that this particular type of random walks provides significant insight into complex transport phenomena. This review provides a self-consistent introduction to L\\'{e}vy walks, surveys their existing applications, including latest advances, and outlines further perspectives.

  4. Walking stick

    NSDL National Science Digital Library

    Clinton Robertson (None; )

    2006-09-23

    Some animals can camouflage themselves in the way that they appear to be an actual element of their environments. The walking stick bug blends into its surroundings because predators probably mistake them for ordinary tree twigs.

  5. Walking Polygons

    NSDL National Science Digital Library

    Exploratorium

    2010-01-01

    In this activity, learners walk the sides and interior angles of various polygons drawn on the playground. As they do so, learners practice rotating clockwise 180° and 360°. Learners discover there is a pattern to the sum of the interior angles of any polygon.

  6. 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...

  7. Quantum random walks without walking

    SciTech Connect

    Manouchehri, K.; Wang, J. B. [School of Physics, University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (Australia)

    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.

  8. JOIN THE WALK! HANDLEMAN WALK FOR AUTISM

    E-print Network

    Cheng, Mei-Fang

    JOIN THE WALK! HANDLEMAN WALK FOR AUTISM a fundraiser to support Douglass Developmental is the Handleman Walk for Autism? The WALK is a fun family event with: Live music, food, moon bouncing, face garden on Rutgers Campus. The event raises funds for children and adults with autism and celebrates

  9. Walking the Walk: A Phenomenological Study of Long Distance Walking

    Microsoft Academic Search

    Lee Crust; Richard Keegan; David Piggott; Christian Swann

    2011-01-01

    Evidence suggests that regular walking can elicit significant psychological benefits, although little evidence exists concerning long distance walking. The purpose of this study was to provide detailed accounts of the experiences of long distance walkers. Phenomenological interviews were conducted with six long distance walkers. Data were transcribed verbatim before researchers independently analyzed the transcripts. Participants reported a cumulative effect with

  10. 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.

  11. Random Walk Learning Machine

    Microsoft Academic Search

    Mircea Andrecut

    2000-01-01

    A simple random walk learning algorithm for associative memories is described. The Hebbian memory matrix optimized by the random walk algorithm leads to a perfect learning in associative memories. Also, in the special case of a binary memory matrix, the random walk learning algorithm leads to an increase of the critical storage density from alphac=0.102 to alphac=0.25.

  12. 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,…

  13. Limit Cycle Walking

    Microsoft Academic Search

    M. Wisse; D. G. E. Hobbelen

    2007-01-01

    This chapter introduces the paradigmLimit Cycle Walking'. This paradigm for the design and control of two-legged walking robots can lead to unprecedented performance in terms of speed, efficiency, disturbance rejection and versatility. This is possible because this paradigm imposes fewer artificial constraints to the robot's walking motion compared to other existing paradigms. The application of artificial constraints is a commonly

  14. Driven Quantum Walks

    NASA Astrophysics Data System (ADS)

    Hamilton, Craig S.; Kruse, Regina; Sansoni, Linda; Silberhorn, Christine; Jex, Igor

    2014-08-01

    We introduce the concept of a driven quantum walk. This work is motivated by recent theoretical and experimental progress that combines quantum walks and parametric down-conversion, leading to fundamentally different phenomena. We compare these striking differences by relating the driven quantum walks to the original quantum walk. Next, we illustrate typical dynamics of such systems and show that these walks can be controlled by various pump configurations and phase matchings. Finally, we end by proposing an application of this process based on a quantum search algorithm that performs faster than a classical search.

  15. Driven Quantum Walks

    E-print Network

    Craig S. Hamilton; Regina Kruse; Linda Sansoni; Christine Silberhorn; Igor Jex

    2014-08-28

    In this letter we introduce the concept of a driven quantum walk. This work is motivated by recent theoretical and experimental progress that combines quantum walks and parametric down- conversion, leading to fundamentally different phenomena. We compare these striking differences by relating the driven quantum walks to the original quantum walk. Next, we illustrate typical dynamics of such systems and show these walks can be controlled by various pump configurations and phase matchings. Finally, we end by proposing an application of this process based on a quantum search algorithm that performs faster than a classical search.

  16. Inhomogeneous Quantum Walks

    E-print Network

    Noah Linden; James Sharam

    2009-06-19

    We study a natural construction of a general class of inhomogeneous quantum walks (namely walks whose transition probabilities depend on position). Within the class we analyze walks that are periodic in position and show that, depending on the period, such walks can be bounded or unbounded in time; in the latter case we analyze the asymptotic speed. We compare the construction to others in the existing literature. As an example we give a quantum version of a non-irreducible classical walk: the Polya Urn.

  17. Walk This Way: A Lightweight, Data-driven Walking Synthesis

    E-print Network

    North Carolina at Chapel Hill, University of

    benefit games. We present a novel walking synthesis model which continuously transforms a single walkingWalk This Way: A Lightweight, Data-driven Walking Synthesis Algorithm Sean Curtis, Ming Lin,lin,dm}@cs.unc.edu http://gamma.cs.unc.edu/Walking Abstract. We present a novel, biomechanically-inspired, kinematic

  18. Random walk on a random walk

    Microsoft Academic Search

    K. W. Kehr; R. Kutner

    1982-01-01

    The authors investigate the random walk of a particle on a one-dimensional chain which has been constructed by a random-walk procedure. Exact expressions are given for the mean-square displacement and the fourth moment after n steps. The probability density after n steps is derived in the saddle-point approximation, for large n. These quantities have also been studied by numerical simulation.

  19. Quaternionic quantum walks

    E-print Network

    Norio Konno

    2015-02-11

    The discrete-time quantum walk (QW) has been extensively and intensively investigated for the last decade, whose coin operator is defined by a unitary matrix. We extend the QW to a walk determined by a unitary matrix whose component is quaternion. We call this model quaternionic quantum walk (QQW) and present some properties. This paper is the first step for the study on QQWs.

  20. Symmetry in quantum walks

    E-print Network

    Hari Krovi

    2007-11-12

    A discrete-time quantum walk on a graph is the repeated application of a unitary evolution operator to a Hilbert space corresponding to the graph. Hitting times for discrete quantum walks on graphs give an average time before the walk reaches an ending condition. We derive an expression for hitting time using superoperators, and numerically evaluate it for the walk on the hypercube for various coins and decoherence models. We show that, by contrast to classical walks, quantum walks can have infinite hitting times for some initial states. We seek criteria to determine if a given walk on a graph will have infinite hitting times, and find a sufficient condition for their existence. The phenomenon of infinite hitting times is in general a consequence of the symmetry of the graph and its automorphism group. Symmetries of a graph, given by its automorphism group, can be inherited by the evolution operator. Using the irreducible representations of the automorphism group, we derive conditions such that quantum walks defined on this graph must have infinite hitting times for some initial states. Symmetry can also cause the walk to be confined to a subspace of the original Hilbert space for certain initial states. We show that a quantum walk confined to the subspace corresponding to this symmetry group can be seen as a different quantum walk on a smaller quotient graph and we give an explicit construction of the quotient graph. We conjecture that the existence of a small quotient graph with finite hitting times is necessary for a walk to exhibit a quantum speed-up. Finally, we use symmetry and the theory of decoherence-free subspaces to determine when the subspace of the quotient graph is a decoherence-free subspace of the dynamics.

  1. Enhanced: Walking Made Simple

    NSDL National Science Digital Library

    R. McNeill Alexander (University of Leeds; School of Biology)

    2005-04-01

    Access to the article is free, however registration and sign-in are required: It is possible to design robots that walk in a humanlike manner by providing them with motors to drive every joint and a computer that tells every joint what its angle should be. There are many successful robots of this ilk, but they are very complex and use far more energy than would a walking human. In his Perspective, Alexander discusses a different type of robot inspired by toys that walk passively downhill. These robots have much simpler control systems and use much less energy than conventional walking robots.

  2. The Bug Walk

    NSDL National Science Digital Library

    Paula Rogers Huff

    2005-01-01

    In this fun group activity involving music and movement, learners are introduced to the idea that many insects walk by using their legs to create "alternating triangles." Learners sing the "Ants Go Marching" song and then study insect specimens. They make models of insects with six legs using Styrofoam and dowels or pencils and brainstorm ideas about how insects walk with all those legs. The most active part of The Bug Walk is when learners, in groups of five, pretend they are an insect's body and simulate an insect's movement. At the end, they discuss what it was like, what problems they had, and ideas for how their walk could have been easier.

  3. Walking boot assembly

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C.; Chambers, A. B.; Stjohn, R. H. (inventors)

    1977-01-01

    A walking boot assembly particularly suited for use with a positively pressurized spacesuit is presented. A bootie adapted to be secured to the foot of a wearer, an hermetically sealed boot for receiving the bootie having a walking sole, an inner sole, and an upper portion adapted to be attached to an ankle joint of a spacesuit, are also described.

  4. Learning-Walk Continuum

    ERIC Educational Resources Information Center

    Finch, Peter Dallas

    2010-01-01

    The continuum of learning walks can be viewed in stages with various dimensions including frequency, participants, purpose and the presence of an instructional framework within which the instructional practice is viewed. Steps in the continuum progress as the learning walks are conducted more frequently. One way to ensure this is accomplished is…

  5. Anyonic quantum walks

    SciTech Connect

    Brennen, Gavin K. [Centre for Quantum Information Science and Security, Macquarie University, 2109, NSW (Australia); Ellinas, Demosthenes [Department of Sciences, Division of Mathematics, Technical University of Crete, GR - 73 100, Chania, Crete (Greece); Kendon, Viv [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Pachos, Jiannis K. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)], E-mail: j.k.pachos@leeds.ac.uk; Tsohantjis, Ioannis [Department of Sciences, Division of Mathematics, Technical University of Crete, GR - 73 100, Chania, Crete (Greece); Wang Zhenghan [Microsoft Research, Station Q, University of California, Santa Barbara, CA 93106 (United States)

    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.

  6. Short Hyperuniform Random Walks

    NASA Astrophysics Data System (ADS)

    Casini, Emanuele; Le Caër, Gérard; Martinelli, Andrea

    2015-04-01

    Random walks of two steps, with fixed sums of lengths of 1 , taken into uniformly random directions in d-dimensional Euclidean spaces (d?2 ) are investigated to construct continuous step-length distributions which make them hyperuniform. The endpoint positions of hyperuniform walks are spread out in the unit ball as the projections in the walk space of points uniformly distributed on the surface of the unit hypersphere of some k-dimensional Euclidean space (k>d ). Unique symmetric continuous step-length distributions exist for given d and k, provided that dwalk becomes uniform on the unit ball when k=d+2 . The symmetric densities reduce to simple polynomials for uniform random walks and are mixtures of two pairs of asymmetric beta distributions.

  7. Learning Energy Efficient Walking with Ballistic Walking

    Microsoft Academic Search

    Masaki Ogino; Koh Hosoda; Minoru Asada

    This paper presents a method for energy efficient walking of a biped robot with a layered controller. The lower layer controller has a state machine for each leg. The state machine consists of four states: First, constant torque is applied to hip and knee joints of the swing leg. Second, no torque is applied so that the swing leg can

  8. 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…

  9. Private Mineral Gallery Walk

    NSDL National Science Digital Library

    Dexter Perkins

    Students make and display posters of the mineral they researched throughout the semester. The instructor and TA review the posters while students answer questions as they walk around and examine each other's posters.

  10. Walking for Your Health

    MedlinePLUS

    Everyday Fitness Ideas from the National Institute on Aging at NIH www.nia.nih.gov/Go4Life Walking for Your ... breathing. Endurance exercises keep you healthy, improve your fitness, and help you do the tasks you need ...

  11. Proper Noun Gallery Walk

    NSDL National Science Digital Library

    Education World

    This site presents a lesson plan that uses a gallery walk and brainstorming to introduce proper nouns. The activity is designed to help students in any grade understand proper nouns and their correct usage.

  12. The Apostle of Walking.

    ERIC Educational Resources Information Center

    Matthews, George R.

    1979-01-01

    Edmund Peyson Weston's long and remarkable career as the father of walking speaks for the benefits of regular exercise through pedestrian activities and a simple life-style based on a moderate approach to eating and personal habits. (LH)

  13. What is Gallery Walk?

    NSDL National Science Digital Library

    Gallery Walk is a discussion technique that gets students out of their chairs and into a mode of active engagement. The advantage of the method is its flexibility and the variety of benefits for students and ...

  14. JungleWalk

    NSDL National Science Digital Library

    2002-01-01

    JungleWalk is a fantastic directory of animal information on the Internet, offering a well-organized and incredibly extensive collection of external links to animal movie and sound clips and interesting Web pages. Netrikon Designs, a "mom and pop" Web design firm, has created JungleWalk as a kid-friendly site that should "still be useful to educators, parents, and anyone interested in animals." Teachers may sign up to receive free sample questionnaires that help make the most of JungleWalk in the classroom. Visitors are encouraged to suggest references to animal Web sites not already included in the collection, or even to contribute an animal audio or video clip of their own.

  15. Snakes and perturbed random walks

    E-print Network

    Basak, Gopal

    2011-01-01

    In this paper we study some properties of random walks perturbed at extrema, which are generalizations of the walks considered e.g., in Davis (1999). This process can also be viewed as a version of {\\em excited random walk}, studied recently by many authors. We obtain a few properties related to the range of the process with infinite memory. We also prove the Strong law, Central Limit Theorem, and the criterion for the recurrence of the perturbed walk with finite memory.

  16. 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…

  17. Random Walk Experiment

    NSDL National Science Digital Library

    Kyle Siegrist

    This resource consists of a Java applet and descriptive text. The applet illustrates a random walk on a discrete time interval from 0 to n. The time n and the probability of a step to the right can be varied. The random variables of interest are the final position, the maximum position, and the time of the last zero.

  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. Mapping Forest Change Walk

    NSDL National Science Digital Library

    The representation depicts a virtual walk through a Virginia forest to examine the impact of a non-native, invasive insect, the hemlock woolly adelgid, on a population of eastern hemlocks. Field research is conducted using the same scientific methodologies and tools that Smithsonian scientists use to monitor forest biodiversity, including scatter graph comparisons and field observations.

  20. Mussels realize Weierstrassian Lévy 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 Lévy walks and it has also been suggested that CCRWs have been mistaken for Lévy walks. Here I test an alternative, emerging hypothesis: namely that some organisms approximate Lévy 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 Lévy walk whose characteristic (power-law) exponent is tuned to nearly minimize the time required to form patterned beds. The mussels realise this Lévy 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

  1. The Walking Droplet Instability

    NASA Astrophysics Data System (ADS)

    Bostwick, Joshua; Steen, Paul

    2013-11-01

    A droplet of liquid that partially wets a solid substrate assumes a spherical-cap equilibrium shape. We show that the spherical-cap with a mobile contact-line is unstable to a non-axisymmetric disturbance and we characterize the instability mechanism, as it depends upon the wetting properties of the substrate. We then solve the hydrodynamic problem for inviscid motions showing that the flow associated with the instability correlates with horizontal motion of the droplet's center-of-mass. We calculate the resulting ``walking speed.'' A novel feature is that the energy conversion mechanism is not unique, so long as the contact-line is mobilized. Hence, the walking droplet instability is potentially significant to a number of industrial applications, such as self-cleansing surfaces or energy harvesting devices.

  2. 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

  3. Take a Planet Walk

    NSDL National Science Digital Library

    Dwight Schuster

    2008-09-01

    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 environment where students generate questions based on their prior knowledge; and challenge students to think critically about the accuracy and limitations of a scale model of our solar system.

  4. Curve walking in crayfish

    PubMed

    Cruse; Saavedra

    1996-01-01

    Curve walking of crayfish Astacus leptodactylus was investigated by exploiting their optomotor response. The animal walked while spatially fixed on a motor-driven treadmill and turning behaviour was induced by an optical stimulus, a pattern consisting of vertical stripes moving in a horizontal direction. In this open-loop situation, the crayfish maintains the same step frequency for the legs on both sides of the body for low and intermediate turning speeds, but increases the step amplitude of the outer legs 2, 3 and 4 by shifting the posterior extreme position (PEP) of these legs in a posterior direction and reduces the step amplitude of inner leg 5 by shifting the PEP of this leg in an anterior direction. Furthermore, the main movement direction of the legs can change relative to the body. This was observed for outer leg 5 and also, at higher turning speeds, for outer leg 2. As coordinating influences between contra- and ipsilateral legs were found directly to influence only the anterior extreme position of the legs, these results indicate that the mechanisms controlling curve walking may be different from those controlling normal leg coordination. PMID:9319377

  5. a walking tour of ALONG THE OLIVE WALK

    E-print Network

    Stoltz, Brian M.

    a walking tour of Caltech ALONG THE OLIVE WALK #12;2 The California Institute of Technology Medal of Technology. Welcome to Caltech! Caltech offers an unparalleled undergraduate education's Hospital LA, and the UCLA Medical Center. The Caltech­UC San Diego Medical Scholars program awards selected

  6. Walk This Way: Humor, Myth and the Image of Walking

    Microsoft Academic Search

    Ellen Vanderslice

    This paper examines stories about walking that are embedded in our culture. The popular culture sources for the stories are mainly comic strips and cartoons, with some news articles, songs and walks from literature and life. The aim is to open an avenue that may lead toward answers to the question, 'Which historical and current images could be useful for

  7. Less Than One-Quarter of California Adults Walk Regularly

    E-print Network

    Diamant, Allison L.; Babey, Susan H.; Hastert, Theresa A.; Brown, E. Richard

    2006-01-01

    walking among African Americans Health Policy Research BriefHealth Interview Survey Walking for Leisure Asians (88%) or African Americans (African American American Indian/ Alaska Native No walking Pacific Islander Regular walking Occasional walking Source: 2003 California Health

  8. Learning to Walk through Imitation

    Microsoft Academic Search

    Rawichote Chalodhorn; David B. Grimes; Keith Grochow; Rajesh P. N. Rao

    2007-01-01

    Programming a humanoid robot to walk is a chal- lenging problem in robotics. Traditional ap- proaches rely heavily on prior knowledge of the robot's physical parameters to devise sophisticated control algorithms for generating a stable gait. In this paper, we provide, to our knowledge, the first demonstration that a humanoid robot can learn to walk directly by imitating a human

  9. Understanding preferences for walking attributes

    Microsoft Academic Search

    Peter Howley; Cathal Buckley; Stephen Hynes; Tom van Rensburg

    2009-01-01

    Formally developed walking routes can have substantial benefits for individuals as a recreational resource and can be a tool for promoting economic development in marginal rural areas. Moreover, the provision of walking trails can facilitate individuals in meeting health related guidelines for physical activity. The overall aim of this paper is to examine respondents’ attitudes towards the formal development and

  10. Focusing Your Walking Intervention's Message

    Microsoft Academic Search

    Daniel L. Friesner; Matthew Q. McPherson; Vivek H. Patil

    2008-01-01

    Public policy makers seek to launch initiatives and preventive measures that reduce spiraling healthcare costs. One way they can do this is by encouraging their constituencies to engage in physical activity, such as walking. Although the health benefits of walking have been well documented, the factors that contribute to such behavior are not well understood. We analyzed the effect of

  11. Random walk in Markovian environment

    Microsoft Academic Search

    Dmitry Dolgopyat; Gerhard Keller; Carlangelo Liverani

    2008-01-01

    We prove a quenched central limit theorem for random walks with bounded increments in a randomly evolving environment on ?d<\\/sup>. We assume that the transition probabilities of the walk depend not too strongly on the environment and that the evolution of the environment is Markovian with strong spatial and temporal mixing properties.

  12. Ranger Walking Initiation Stephanie Schneider

    E-print Network

    Ruina, Andy L.

    was ultimately to design and implement walking initiation, from standing still, for the Cornell Ranger. Since I initial conditions, Ranger was able to independently switch from standing still to steadystate walking, and explained how he envisioned it working: his idea was to have Ranger rock back and forth several times (the

  13. Quantum walks on quotient graphs

    SciTech Connect

    Krovi, Hari; Brun, Todd A. [Communication Sciences Institute, University of Southern California, Los Angeles, California 90089 (United States)

    2007-06-15

    A discrete-time quantum walk on a graph {gamma} is the repeated application of a unitary evolution operator to a Hilbert space corresponding to the graph. If this unitary evolution operator has an associated group of symmetries, then for certain initial states the walk will be confined to a subspace of the original Hilbert space. Symmetries of the original graph, given by its automorphism group, can be inherited by the evolution operator. We show that a quantum walk confined to the subspace corresponding to this symmetry group can be seen as a different quantum walk on a smaller quotient graph. We give an explicit construction of the quotient graph for any subgroup H of the automorphism group and illustrate it with examples. The automorphisms of the quotient graph which are inherited from the original graph are the original automorphism group modulo the subgroup H used to construct it. The quotient graph is constructed by removing the symmetries of the subgroup H from the original graph. We then analyze the behavior of hitting times on quotient graphs. Hitting time is the average time it takes a walk to reach a given final vertex from a given initial vertex. It has been shown in earlier work [Phys. Rev. A 74, 042334 (2006)] that the hitting time for certain initial states of a quantum walks can be infinite, in contrast to classical random walks. We give a condition which determines whether the quotient graph has infinite hitting times given that they exist in the original graph. We apply this condition for the examples discussed and determine which quotient graphs have infinite hitting times. All known examples of quantum walks with hitting times which are short compared to classical random walks correspond to systems with quotient graphs much smaller than the original graph; we conjecture that the existence of a small quotient graph with finite hitting times is necessary for a walk to exhibit a quantum speedup.

  14. Is slow walking more stable?

    PubMed

    Bruijn, Sjoerd M; van Dieën, Jaap H; Meijer, Onno G; Beek, Peter J

    2009-07-22

    Several efforts have been made to study gait stability using measures derived from nonlinear time-series analysis. The maximum finite time Lyapunov exponent (lambda(max)) quantifies how a system responds to an infinitesimally small perturbation. Recent studies suggested that slow walking leads to lower lambda(max) values, and thus is more stable than fast walking, but these studies suffer from methodological limitations. We studied the effects of walking speed on the amount of kinematic variability and stability in human walking. Trunk motions of 15 healthy volunteers were recorded in 3D during 2 min of treadmill walking at different speeds. From those time series, maximum Lyapunov exponents, indicating short-term and long-term divergence (lambda(S-stride) and lambda(L-stride)), and mean standard deviation (MeanSD) were calculated. lambda(S-stride) showed a linear decrease with increasing speed for forward-backward (AP) movements and quadratic effects (inverted U-shaped) for medio-lateral (ML) and up-down (VT) movements. lambda(L-stride) showed a quadratic effect (inverted U-shaped) of walking speed for AP movements, a linear decrease for ML movements, and a linear increase for VT movements. Moreover, positive correlations between lambda(S) and MeanSD were found for all directions, while lambda(L-stride) and MeanSD were correlated negatively in the AP direction. The different effects of walking speed on lambda(S-stride) and lambda(L-stride) for the different planes suggest that slow walking is not necessarily more stable than fast walking. The absence of a consistent pattern of correlations between lambda(L-stride) and MeanSD over the three directions suggests that variability and stability reflect, at least to a degree, different properties of the dynamics of walking. PMID:19446294

  15. A Reinforcement Learning Based Dynamic Walking Control

    Microsoft Academic Search

    Yong Mao; Jiaxin Wang; Peifa Jia; Shi Li; Zhen Qiu; Le Zhang; Zhuo Han

    2007-01-01

    A quasi-passive dynamic walking robot is built to study natural and energy-efficient biped walking. The robot is actuated by MACCEPA actuators. A reinforcement learning based control method is proposed to enhance the robustness and stability of the robot's walking. The proposed method first learns the desired gait for the robot's walking on a flat floor. Then a fuzzy advantage learning

  16. Two Models of Quantum Random Walk

    Microsoft Academic Search

    Jozef Ko

    We present an overview of two models of quantum random walk. In the › rst model, the discrete quantum random walk, we present the explicit solution for the recurring amplitude of the quantum random walk on a one-dimensional lattice. We also introduce a new method of solving the problem of random walk in the most general case and use it

  17. Coalescing random walks and voting on graphs

    Microsoft Academic Search

    Colin Cooper; Robert Elsässer; Hirotaka Ono; Tomasz Radzik

    2012-01-01

    In a coalescing random walk, a set of particles make independent discrete-time random walks on a graph. Whenever one or more particles meet at a vertex, they unite to form a single particle, which then continues the random walk through the graph. Coalescing random walks can be used to achieve consensus in distributed networks, and is the basis of the

  18. Slow-walking inflation

    SciTech Connect

    Erdmenger, Johanna; Halter, Sebastian [Max-Planck-Institut für Physik, Föhringer Ring 6, 80805 München (Germany); Núñez, Carlos [Department of Physics, University of Swansea, Singleton Park, Swansea SA2 8PP (United Kingdom); Tasinato, Gianmassimo, E-mail: jke@mppmu.mpg.de, E-mail: s.halter@physik.uni-muenchen.de, E-mail: c.nunez@swansea.ac.uk, E-mail: gianmassimo.tasinato@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)

    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.

  19. Fault-Tolerant Quantum Walks

    E-print Network

    S. D. Freedman; Y. H. Tong; J. B. Wang

    2014-08-06

    Quantum walks are expected to serve important modelling and algorithmic applications in many areas of science and mathematics. Although quantum walks have been successfully implemented physically in recent times, no major efforts have been made to combat the error associated with these physical implementations in a fault-tolerant manner. In this paper, we propose a systematic method to implement fault-tolerant quantum walks in discrete time on arbitrarily complex graphs, using quantum states encoded with the Steane code and a set of universal fault tolerant matrix operations.

  20. Walking Robot Locomotion System Conception

    NASA Astrophysics Data System (ADS)

    Ignatova, D.; Abadjieva, E.; Abadjiev, V.; Vatzkitchev, Al.

    2014-09-01

    This work is a brief analysis on the application and perspective of using the walking robots in different areas in practice. The most common characteristics of walking four legs robots are presented here. The specific features of the applied actuators in walking mechanisms are also shown in the article. The experience of Institute of Mechanics - BAS is illustrated in creation of Spiroid and Helicon1 gears and their assembly in actuation of studied robots. Loading on joints reductors of robot legs is modelled, when the geometrical and the walking parameters of the studied robot are preliminary defined. The obtained results are purposed for designing the control of the loading of reductor type Helicon in the legs of the robot, when it is experimentally tested.

  1. Quantum Snake Walk on Graphs

    E-print Network

    Ansis Rosmanis

    2010-08-18

    I introduce a new type of 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 which 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. No efficient quantum algorithm solving this problem is known yet.

  2. Quantum snake walk on graphs

    SciTech Connect

    Rosmanis, Ansis [David R. Cheriton School of Computer Science and Institute for Quantum Computing, University of Waterloo, West Waterloo, Ontario, N2L 3G1 (Canada)

    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.

  3. Gallery Walk Questions about Coastlines

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about coastlines. The questions are organized according to the cognitive ...

  4. Gallery Walk Questions about Volcanism

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about volcanism. The questions are organized according to the cognitive ...

  5. Gallery Walk Questions about Glaciers

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about glaciers. The questions are organized according to the cognitive level ...

  6. Gallery Walk Questions on Karst

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about karst. The questions are organized according to the cognitive level at ...

  7. Walking Safely in Rural Areas

    MedlinePLUS

    ... in the country: l Always walk facing oncoming traffic. l Look for a smooth, stable surface alongside ... a paved shoulder, stay as far away from traffic as possible. l Watch for bridges and narrow ...

  8. Solar walk-off protection

    Microsoft Academic Search

    H. Awaya; R. Bedard

    1985-01-01

    A point-focus solar concentrator is normally pointed toward the sun during operations to direct concentrated solar flux into the aperture of the receiver. If solar-tracking control is lost, severe damage may occur when the concentrated solar beam moves, or walks off the aperture across the face of the receiver. Alternative methods of solar walk-off prevention\\/protection for a specific assumed generic

  9. Science Sampler: The Element Walk

    NSDL National Science Digital Library

    Dennis Smithenry

    2010-10-01

    “The Element Walk” lesson is effective at teaching students the elements that exist in common substances encountered every day. Students walk away from the lesson with a set of general rules that help them to easily identify the elements around them. They also end up with a greater appreciation of the elemental compositions of living, once-living, and nonliving objects, and the connections among the three categories.

  10. Walking Behavior in Technicolored GUTs

    E-print Network

    A. Doff

    2009-02-19

    There exist two ways to obtain walk behavior: assuming a large number of technifermions in the fundamental representation of the technicolor (TC) gauge group, or a small number of technifermions, assuming that these fermions are in higher-dimensional representations of the TC group. We propose a scheme to obtain the walking behavior based on technicolored GUTs (TGUTs), where elementary scalars with the TC degree of freedom may remain in the theory after the GUT symmetry breaking.

  11. 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 (2010–2012) 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 “walker’s 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

  12. Walking with Prehistoric Beasts

    NSDL National Science Digital Library

    2001-01-01

    Nope, it's not about dinosaurs but it is just as fascinating! "Walking with Prehistoric Beasts is the Discovery Channel's new television series on the creatures that inhabited Earth after the dinosaurs disappeared 65 million years ago (mya). The program's companion Website offers fabulous graphics and games, with a little bit of informative text mixed in, about such beasts as Gastornis, a meat-loving bird the size of a tall human, Propalaeotherium, a 43 million year old cat-sized horse, and Andrewsarchus, a furry, land-dwelling ancestor of the whale. Facts on pronunciation, etymology, geologic time range, body size, diet, geographic range and closest living relative are given for every animal in the Beast Gallery. When visiting this site you should not miss the How do We Know section, housing audio recordings of paleontologists answering your e.mail questions (Real/Windows Media) or the Changing Worlds game in which players control a map of Earth showing vegetation, mammal life and ocean currents from 65 mya to present. Plus, you can test your beast-mastery with the Beastly Quiz.

  13. Walking on ballast impacts balance.

    PubMed

    Wade, Chip; Garner, John C; Redfern, Mark S; Andres, Robert O

    2014-01-01

    Railroad workers often perform daily work activities on irregular surfaces, specifically on ballast rock. Previous research and injury epidemiology have suggested a relationship between working on irregular surfaces and postural instability. The purpose of this study was to examine the impact of walking on ballast for an extended duration on standing balance. A total of 16 healthy adult males walked on a 7.62 m × 4.57 m (25 ft × 15 ft) walking surface of no ballast (NB) or covered with ballast (B) of an average rock size of about 1 inch for 4 h. Balance was evaluated using dynamic posturography with the NeuroCom(®) Equitest System(™) prior to experiencing the NB or B surface and again every 30 min during the 4 h of ballast exposure. Dependent variables were the sway velocity and root-mean-square (RMS) sway components in the medial-lateral and anterior-posterior directions. Repeated measures ANOVA revealed statistically significant differences in RMS and sway velocity between ballast surface conditions and across exposure times. Overall, the ballast surface condition induced greater sway in all of the dynamic posturography conditions. Walking on irregular surfaces for extended durations has a deleterious effect on balance compared to walking on a surface without ballast. These findings of changes in balance during ballast exposure suggest that working on an irregular surface may impact postural control. PMID:24354716

  14. 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

  15. Quantum Walks, Quantum Gates and Quantum Computers

    E-print Network

    Andrew P. Hines; P. C. E. Stamp

    2007-01-14

    The physics of quantum walks on graphs is formulated in Hamiltonian language, both for simple quantum walks and for composite walks, where extra discrete degrees of freedom live at each node of the graph. It is shown how to map between quantum walk Hamiltonians and Hamiltonians for qubit systems and quantum circuits; this is done for both a single- and multi-excitation coding, and for more general mappings. Specific examples of spin chains, as well as static and dynamic systems of qubits, are mapped to quantum walks, and walks on hyperlattices and hypercubes are mapped to various gate systems. We also show how to map a quantum circuit performing the quantum Fourier transform, the key element of Shor's algorithm, to a quantum walk system doing the same. The results herein are an essential preliminary to a Hamiltonian formulation of quantum walks in which coupling to a dynamic quantum environment is included.

  16. On Convergent Probability of a Random Walk

    ERIC Educational Resources Information Center

    Lee, Y.-F.; Ching, W.-K.

    2006-01-01

    This note introduces an interesting random walk on a straight path with cards of random numbers. The method of recurrent relations is used to obtain the convergent probability of the random walk with different initial positions.

  17. Random Walks and Electrical Networks Electrical Network Calculations in Random Walks in

    E-print Network

    Peterson, Jonathon

    Random Walks and Electrical Networks Electrical Network Calculations in Random Walks in Random 2/4/2008 1 / 23 #12;Random Walks and Electrical Networks Much of this talk is based on the book Random Walks and Electric Networks by Peter G. Doyle and J. Laurie Snell. Free download available at http

  18. TESTING OF THE FE WALKING ROBOT MAY 2006 1 Testing of the FE Walking Robot

    E-print Network

    Ruina, Andy L.

    TESTING OF THE FE WALKING ROBOT MAY 2006 1 Testing of the FE Walking Robot Elianna R Weyer, May and result of testing the FE walking robot during spring 2006. Improve- ments in code and launch technique. The author predicts that with continued optimization and testing, the FE walking robot can surpass

  19. A Walking School Bus Program Increased Students' Walking to School and Decreased Transport by Car

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Walking school buses are popular programs designed to overcome barriers and increase the numbers of children who walk to school. We tested the hypothesis that a walking school bus program would increase the proportion of children walking to school and decrease the proportion transported to school by...

  20. Two models of quantum random walk

    Microsoft Academic Search

    Jozef Kosík

    2003-01-01

    We present an overview of two models of quantum random walk. In the first model, the discrete quantum random walk, we present\\u000a the explicit solution for the recurring amplitude of the quantum random walk on a one-dimensional lattice. We also introduce\\u000a a new method of solving the problem of random walk in the most general case and use it to

  1. 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…

  2. Walking in (Affective) Circles: Can Short Walks Enhance Affect?

    Microsoft Academic Search

    Panteleimon Ekkekakis; Eric E. Hall; Lisa M. VanLanduyt; Steven J. Petruzzello

    2000-01-01

    Recent physical activity recommendations call for activities that are of moderate intensity and can be performed intermittently during the day, such as walking. These proclamations were based partly on the assumption that moderate activities are generally more enjoyable than physically demanding ones, and they are, therefore, also more likely to be continued over the long haul. However, little is actually

  3. Limit Theorems for the Fibonacci Quantum Walk

    E-print Network

    Clement Ampadu

    2011-08-25

    We study the discrete-time quantum walk in one-dimension governed by the Fibonacci transformation .We show localization does not occur for the Fibonacci quantum walk by investigating the stationary distribution of the walk, in addition, we obtain the weak limit theorem.

  4. Limit Theorems for the Fibonacci Quantum Walk

    E-print Network

    Ampadu, Clement

    2011-01-01

    We study the discrete-time quantum walk in one-dimension governed by the Fibonacci transformation .We show localization does not occur for the Fibonacci quantum walk by investigating the stationary distribution of the walk, in addition, we obtain the weak limit theorem.

  5. Biped walking pattern generation using reinforcement learning

    Microsoft Academic Search

    Jungho Lee; Jun Ho Oh

    2007-01-01

    In this research, a stable biped walking pattern is generated. The walking pattern is a simple third order polynomial. To find the proper boundary condition, the reinforcement learning algorithm is used. The final velocity of the walking pattern is chosen as learning parameter. To test the algorithm, a simulator that includes the reaction between the foot of the robot and

  6. Diss. ETH No 13748 WALKING GAIT CONTROL

    E-print Network

    Still, Susanna

    controllers of this type, and (ii) the demonstration of walking gait learning in a novel way using the chipDiss. ETH No 13748 WALKING GAIT CONTROL FOR FOUR-LEGGED ROBOTS Bio-inspired technology analyzed for the inter-leg coordination of four-legged walking machines. The controller is implemented using Very Large

  7. Fourier series learning of biped walking motion

    Microsoft Academic Search

    T. Y. Kuc; S. M. Baek; H. G. Lee; J. O. Kim

    2002-01-01

    A learning controller is presented for repetitive walking motion of biped robot. The learning control scheme learns the approximate inverse dynamics input of biped walking robot and uses the learned input pattern to generate an input profile of different walking motion. In the learning controller, the PID feedback controller takes part in stabilizing the transient response of robot dynamics while

  8. RANDOM WALK IN DETERMINISTICALLY CHANGING ENVIRONMENT

    E-print Network

    Liverani, Carlangelo

    RANDOM WALK IN DETERMINISTICALLY CHANGING ENVIRONMENT DMITRY DOLGOPYAT AND CARLANGELO LIVERANI Abstract. We consider a random walk with transition probabilities weakly dependent on an environment of the environment the walk satisfies the CLT. 1. Introduction The continuing interest in the limit properties

  9. Generalized Open Quantum Walks on Apollonian Networks

    PubMed Central

    Pawela, ?ukasz; Gawron, Piotr; Miszczak, Jaros?aw Adam; Sadowski, Przemys?aw

    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

  10. Humanoid robot walking control on inclined planes

    Microsoft Academic Search

    Utku Seven; Tunc Akbas; Kaan Can Fidan; Metin Yilmaz; Kemalettin Erbatur

    2011-01-01

    The humanoid bipedal structure is suitable for a assitive robot functioning in the human environment. However, the bipedal walk is a difficult control problem. Walking just on even floor is not satisfactory for the applicability of a humanoid robot. This paper presents a study on bipedal walk on inclined planes. A Zero Moment Point (ZMP) based reference generation technique is

  11. Sensors and Control Concept of Walking 'Johnnie

    Microsoft Academic Search

    Klaus Löffler; Michael Gienger; Friedrich G Pfeiffer

    2003-01-01

    One key problem to achieve a dynamically stable walking motion with biped robots is to measure and control the actual state of the robot with respect to its environment. Dynamically stable walking on unstructured terrain and fast walking can only be achieved with an orientation sensor. The control system of the biped robot \\

  12. PERSISTENCE OF ITERATED RANDOM WALKS VLADISLAV VYSOTSKY

    E-print Network

    Vysotsky, Vladislav

    of general integrated random walks was deeply connected to behavior of sticky particle systems with random that Y (n) is a random walk. Denote Tn the sequence of its (weak) ascending ladder moment and Hn := Y (Tn) its ladder hights. The sequence (Tn, Hn) is a bivariate random walk, and we put Tn := Tn - Tn-1 and Hn

  13. Energy Gallery Walk

    NSDL National Science Digital Library

    Katharine Ellis

    Each student has been given a packet of information on an energy topic. There are two articles that all the students will receive, on energy conservation and addiction to oil, and then several others on their specific topic. Each student will be instructed to become the classroom expert on their specific topic by reading the articles and being invited to look up more information. These steps are modified from Step by Step Instructions for Gallery Walk I learned this technique at a Cutting Edge workshop put on by the National Association of Geoscience Teachers called Designing Innovative and Effective Geoscience Courses in the summer of 2008. The steps to this lesson are: I have generated a list of questions around energy. The questions will be written on poster-sized paper, one question to each sheet. The questions will be posted in a foyer area. The students have been given general directions in the previous class, and more specific directions will be given the day of the event. The students have been prepared by reading packets of energy information, as described above in this document. They have also been advised on how the grading rubric and feedback will be used. The students will be put into groups of two, because the class is so small. Each group will have a different colored marker. If the groups were larger, roles would be assigned, like recorder, speaker, emissary, etc... That won't work with this small class. We will begin the gallery walk. Each team will start at a different chart, read the question, talk to each other, then document their response in their colored ink. They will be encouraged to write in a pithy bulleted format closest to the top of the chart. The teams will rotate to a new station after a period of time (to be determined!) They will rotate clockwise. Arriving at a new station, the students will read the question, the responses of the other groups who posted before them, and add their comments, sort of like a BLOG. The groups can switch recorders at each station to keep all members involved. I will monitor the students' progress. I may have to intervene to clarify a point or direct the students to think of something they may have overlooked. I will wander between groups, listening in, and asking "Socratic" guiding questions if needed. Once all groups have responded to all the posters, they can return to posters to read the other postings, and even add to their own comments. After the rotations and comment period, students will "report out", which each group synthesizes the comments for each question into a summary. The groups will then take turns making oral reports on the questions at hand. I may decide to have them do a written report instead, so that they create a document to refer to later in the course. I will be gauging student understanding throughout the report stage, to reinforce correctly expressed concepts and correct for errors or misconceptions. The questions my students had to answer were: What sources of energy (conventional and alternative-yet-to-be-brought-to-market) are appropriate powering motor vehicles? In detail, what are the advantages and disadvantages of each? What sources of energy (conventional and alternative) are appropriate for powering homes? (Heat, hot water, cooking, cooling, light, etc) In detail, what are the advantages and disadvantages? What are the most polluting energy sources, and what type of pollution do they produce? What are the least polluting energy sources, and why aren't we using them more? What are fifteen ways the average person can conserve energy? Do we need to conserve energy? Do developing nations need to? Why or why not? Should energy conservation be a legal mandate from the U.S. government for our citizens? Should the U.N. require international consensus on energy conservation? Would that be fair to developing nations? What are the reasons we can no longer depend on fossil fuels (both domestic and imported) to power the United States of America? What are the great issues at stake? Who will pay the price for energy decisions made (or not

  14. 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…

  15. Walk for Fun and Fitness.

    ERIC Educational Resources Information Center

    Milne, Conrad

    1994-01-01

    A school-based walking program is an inexpensive and amusing way to get young students physically active. The article presents a program that can be adapted for students of any age and implemented as a physical education class unit, after school activity, or recess program. (SM)

  16. Quantum Walk Based Search Algorithms

    Microsoft Academic Search

    Miklos Santha

    2008-01-01

    In this survey paper we give an intuitive treatment of the discrete time quantization of classical Markov chains. Grover search and the quantum walk based search algorithms of Ambainis, Szegedy and Magniez et al. will be stated as quantum analogues of classical search procedures. We present a rather detailed description of a somewhat sim- plified version of the MNRS algorithm.

  17. Walk Through a Hydroelectric Project

    NSDL National Science Digital Library

    This site offers a virtual walk-through tour of a hydroelectric facility. The creation of hydroelectricity begins at the dam, where the power plant converts the force of falling water into electricity. It shows how dams operate and the equipment necessary for electrical generation.

  18. Water-Walking Submitted by

    E-print Network

    Bush, John W.M.

    Water-Walking Submitted by David L. Hu, Brian Chan, and John W. M. Bush, Massachusetts Institute of Technology The water strider Fig. 1 is an insect of characteristic length 1 cm and weight 10 dynes of hairs that render its legs effectively nonwetting.1 The water strider propels itself by driving its

  19. Science Sampler: Walking Out Graphs

    NSDL National Science Digital Library

    Ji Shen

    2009-12-01

    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 transforming among these representation (Shen and Confrey 2007).

  20. Stereo matching using random walks

    Microsoft Academic Search

    Rui Shen; Irene Cheng; Xiaobo Li; Anup Basu

    2008-01-01

    This paper presents a novel two-phase stereo matching algorithm using the random walks framework. At first, a set of reliable matching pixels is extracted with prior matrices defined on the penalties of different disparity configurations and Laplacian matrices defined on the neighbourhood information of pixels. Following this, using the reliable set as seeds, the disparities of unreliable regions are determined

  1. Random walking during quiet standing

    NASA Astrophysics Data System (ADS)

    Collins, J. J.; de Luca, C. J.

    1994-08-01

    During quiet standing, the human body continually moves about in an erratic, and possibly chaotic, fashion. Here we show that postural sway is indistinguishable from correlated noise and that it can be modeled as a system of bounded, correlated random walks. These novel results suggest that the postural control system incorporates both open-loop and closed-loop control mechanisms.

  2. WW Scattering in Walking Technicolor

    E-print Network

    Roshan Foadi; Francesco Sannino

    2008-01-04

    We analyze the WW scattering in scenarios of dynamical electroweak symmetry breaking of walking technicolor type. We show that in these theories there are regions of the parameters space allowed by the electroweak precision data, in which unitarity violation is delayed at tree level up to around 3-4 TeV without the inclusion of any sub-TeV resonances.

  3. Walk This Way for Health

    Microsoft Academic Search

    Billie Giles-Corti

    2001-01-01

    Walking was firmly put on the public health agenda in 1996 following publication of the US Surgeon General's Report on Physical Activity. This report coincided with growing international concern about the burden of obesity, which in developed countries, is contributed to by increasingly inactive lifestyles. After reviewing decades of epidemiologic al evidence, the US Surgeon General concluded that physical inactivity

  4. Thermally Actuated Omnidirectional Walking Microrobot

    Microsoft Academic Search

    E. Yegân Erdem; Yu-Ming Chen; Matthew Mohebbi; John W. Suh; Gregory T. A. Kovacs; Robert B. Darling; Karl F. Bohringer

    2010-01-01

    We describe a walking microrobot that is propelled by cilialike thermal bimorph actuator arrays. The robot consists of two actuator array chips, each having an 8 × 8 array of “motion pixels,” which are composed of four orthogonally oriented cilia. Each group of unidirectional cilia is controlled independently for each chip, which provides planar motion with three degrees of freedom

  5. Random walk through fractal environments

    Microsoft Academic Search

    H. Isliker; L. Vlahos

    2003-01-01

    We analyze random walk through fractal environments, embedded in three-dimensional, permeable space. Particles travel freely and are scattered off into random directions when they hit the fractal. The statistical distribution of the flight increments (i.e., of the displacements between two consecutive hittings) is analytically derived from a common, practical definition of fractal dimension, and it turns out to approximate quite

  6. Financial Planning Using Random Walks

    Microsoft Academic Search

    John Norstad

    2005-01-01

    We develop an enhanced random walk model for retirement planning. Our model includes a new term to accommodate periodic additions to or withdrawals from a portfolio. We deal with the problems of modeling social security, salary growth, inflation, investment expenses, and asset allocation among cash, bonds, and stocks. We investigate a basic problem of post-retirement planning, the risk of outliving

  7. 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…

  8. Does walking change the Romberg sign?

    PubMed Central

    Findlay, Gordon F. G.; Trivedi, Jayesh M.; Jaffray, David C.

    2009-01-01

    The Romberg sign helps demonstrate loss of postural control as a result of severely compromised proprioception. There is still no standard approach to applying the Romberg test in clinical neurology and the criteria for and interpretation of an abnormal result continue to be debated. The value of this sign and its adaptation when walking was evaluated. Detailed clinical examination of 50 consecutive patients of cervical myelopathy was performed prospectively. For the walking Romberg sign, patients were asked to walk 5 m with their eyes open. This was repeated with their eyes closed. Swaying, feeling of instability or inability to complete the walk with eyes closed was interpreted as a positive walking Romberg sign. This test was compared to common clinical signs to evaluate its relevance. Whilst the Hoffman’s reflex (79%) was the most prevalent sign seen, the walking Romberg sign was actually present in 74.5% of the cases. The traditional Romberg test was positive in 17 cases and 16 of these had the walking Romberg positive as well. Another 21 patients had a positive walking Romberg test. Though not statistically significant, the mean 30 m walking times were slower in patients with traditional Romberg test than in those with positive walking Romberg test and fastest in those with neither of these tests positive. The combination of either Hoffman’s reflex and/or walking Romberg was positive in 96% of patients. The walking Romberg sign is more useful than the traditional Romberg test as it shows evidence of a proprioceptive gait deficit in significantly more patients with cervical myelopathy than is found on conventional neurological examination. The combination of Hoffman’s reflex and walking Romberg sign has a potential as useful screening tests to detect clinically significant cervical myelopathy. PMID:19387702

  9. 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

  10. Electrochemical random-walk theory

    Microsoft Academic Search

    Ian J. Cutress; Edmund J. F. Dickinson; Richard G. Compton

    2011-01-01

    Electrochemical simulation is employed to investigate voltammetry in solutions of very low concentrations. Using Monte Carlo random-walk simulations, potential-step chronoamperometry is considered from the perspective of individual species under Brownian motion in solution interacting with an electroactive surface for electron transfer. This allows the exploration of stochastic versus statistical diffusion, where the latter is described by continuous theory (Fick’s laws

  11. ccsd00002924, On the concentration of Sinai's walk

    E-print Network

    ccsd­00002924, version 1 ­ 26 Jan 2005 On the concentration of Sinai's walk Pierre Andreoletti y Sinai's random walk in random environment. We prove that for an interval of time [1; n] Sinai's walk sites of the walk and to the maximum of the local time. 1 Introduction Random Walks in Random

  12. Active online learning of the bipedal walking

    Microsoft Academic Search

    Dingsheng Luo; Yi Wang; Xihong Wu

    2011-01-01

    For legged robot walking pattern learning, the current mainstream and state-of-the-art researches are most under a so-called computer simulation based framework, where the walking pattern is learned via a pre-established simulation platform. However, when the learned walking pattern is applied to a real robot, an additional adapting procedure is always required, due to the big difference between simulation and real

  13. Metastable Walking on Stochastically Rough Terrain

    Microsoft Academic Search

    Katie Byl; Russ Tedrake

    Simplified models of limit-cycle walking on flat terrain have provided important insights into the nature of legged locomotion. Real walking robots (and humans), however, do not exhibit true limit cycle dynamics because terrain, even in a carefully designed laboratory setting, is inevitably non-flat. Walking systems on stochastically rough terrain may not satisfy strict conditions for limit-cycle stability but can still

  14. 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.

  15. Biomechanics and muscle coordination of human walking

    Microsoft Academic Search

    Felix E. Zajac; Richard R. Neptune; Steven A. Kautz

    2002-01-01

    Current understanding of how muscles coordinate walking in humans is derived from analyses of body motion, ground reaction force and EMG measurements. This is Part I of a two-part review that emphasizes how muscle-driven dynamics-based simulations assist in the understanding of individual muscle function in walking, especially the causal relationships between muscle force generation and walking kinematics and kinetics. Part

  16. 76 FR 21579 - Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-15

    ...Part 431 Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In...1904-AB85 Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In...January 2010 NOPR) to establish new test procedures for walk-in coolers and...

  17. Knee Stretch Walking Method for Biped Robot: Using Toe and Heel Joints to Increase Walking Strides

    NASA Astrophysics Data System (ADS)

    Sato, Takahiko; Shimmyo, Shuhei; Nakazato, Miki; Mikami, Kei; Sato, Tomoya; Sakaino, Sho; Ohnishi, Kouhei

    This paper proposes a knee stretch walking method for biped robots; the method involves the use of the toes and heel joints to increase walking strides. A knee can be stretched by switching control variables. By a knee stretch walking with heel contacts to the ground and toe takeoffs from the ground, biped robots can increase their walking stride and speed. The validity of the proposed method is confirmed by simulation and experimental results.

  18. Efficient quantum circuit implementation of quantum walks

    SciTech Connect

    Douglas, B. L.; Wang, J. B. [School of Physics, University of Western Australia, 6009 Perth (Australia)

    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.

  19. How Well Do Random Walks Parallelize?

    NASA Astrophysics Data System (ADS)

    Efremenko, Klim; Reingold, Omer

    A random walk on a graph is a process that explores the graph in a random way: at each step the walk is at a vertex of the graph, and at each step it moves to a uniformly selected neighbor of this vertex. Random walks are extremely useful in computer science and in other fields. A very natural problem that was recently raised by Alon, Avin, Koucky, Kozma, Lotker, and Tuttle (though it was implicit in several previous papers) is to analyze the behavior of k independent walks in comparison with the behavior of a single walk. In particular, Alon et al. showed that in various settings (e.g., for expander graphs), k random walks cover the graph (i.e., visit all its nodes), ?(k)-times faster (in expectation) than a single walk. In other words, in such cases k random walks efficiently “parallelize” a single random walk. Alon et al. also demonstrated that, depending on the specific setting, this “speedup” can vary from logarithmic to exponential in k.

  20. Thermodynamics and entanglements of walks under stress

    NASA Astrophysics Data System (ADS)

    Janse van Rensburg, E. J.; Orlandini, E.; Tesi, M. C.; Whittington, S. G.

    2009-07-01

    We use rigorous arguments and Monte Carlo simulations to study the thermodynamics and the topological properties of self-avoiding walks on the cubic lattice subjected to an external force f. The walks are anchored at one or both endpoints to an impenetrable plane at Z = 0 and the force is applied in the Z-direction. If a force is applied to the free endpoint of an anchored walk, then a model of pulled walks is obtained. If the walk is confined to a slab and a force is applied to the top bounding plane, then a model of stretched walks is obtained. For both models we prove the existence of the limiting free energy for any value of the force and we show that, for compressive forces, the thermodynamic properties of the two models differ substantially. For pulled walks we prove the existence of a phase transition that, by numerical simulation, we estimate to be second order and located at f = 0. By using a pattern theorem for large positive forces we show that almost all sufficiently long stretched walks are knotted. We examine the entanglement complexity of stretched and pulled walks; our numerical results show a sharp reduction with increasing pulling and stretching forces. Finally, we also examine models of pulled and stretched loops. We prove the existence of limiting free energies in these models and consider the knot probability numerically as a function of the applied pulling or stretching force.

  1. Walking without optic flow reduces subsequent vection.

    PubMed

    Seno, Takeharu; Palmisano, Stephen; Riecke, Bernhard E; Nakamura, Shinji

    2015-01-01

    This experiment investigated the effect of walking without optic flow on subsequent vection induction and strength. Two groups of participants walked for 5 min (either wearing Ganzfeld goggles or with normal vision) prior to exposure to a vection-inducing stimulus. We then measured the onset latency and strength of vection induced by a radially expanding pattern of optic flow. The results showed that walking without optic flow transiently yielded later vection onsets and reduced vection strength. We propose that walking without optic flow triggered a sensory readjustment, which reduced the ability of optic flow to induce self-motion perception. PMID:25273923

  2. The Self-Avoiding Random Walk

    NSDL National Science Digital Library

    Buldyrev, Sergey

    This site provides the description and instructions for as well as the link to "The Self-Avoiding Random Walk" applet. In the SAW applet, random walks start on a square lattice and then are discarded as soon as they self-intersect. If a random walk survives after N steps, we compute the square of the distance from the origin, sum it up, and divide by the number of survivals. This variable is plotted on the vertical axis of the graph, which is plotted to the right of the field where random walks travel.

  3. 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

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

    Microsoft Academic Search

    J Michael Oakes; Ann Forsyth; Kathryn H Schmitz

    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

  5. BEHAVIOUR AND MOTOR OUTPUT OF STICK INSECTS WALKING ON A SLIPPERY SURFACE I. FORWARD WALKING

    Microsoft Academic Search

    S. EPSTEIN; D. GRAHAM

    1983-01-01

    SUMMARY The walking coordination and motor output of intact adult stick insects was examined when they were supported above an oiled glass surface. The viscosity of the silicone oil was adjusted so that the animal walked with either tripod or slow-walk coordination. In the absence of mechanical coupling through the substrate, the legs typically moved at different speeds in retrac-

  6. Walking for Mental Vitality: Some Psychological Benefits of Walking in Natural Settings

    Microsoft Academic Search

    Raymond De Young

    The benefits to society from walking are many (e.g., economic, social, environmental) and a variety of personal motives support walking including utilitarian travel, increased physical health, and the intrinsic benefits of recreation and social interaction. There is now emerging a new reason for walking which both benefits society and is motivating to the individual. It focuses on mental (attentional) restoration.

  7. A walk of art: the potential of the sound walk as practice in cultural geography

    Microsoft Academic Search

    Toby Butler

    2006-01-01

    Some of the most experimental and exciting work using sound and spatiality has come from the art world. This essay traces how an exciting hybrid of sound art and walking – the sound walk - has evolved over the last century. Examining the latest examples of sound walks in London and New York, and reflecting on the author's experience of

  8. IMU-based ambulatory walking speed estimation in constrained treadmill and overground walking.

    PubMed

    Yang, Shuozhi; Li, Qingguo

    2012-01-01

    This study evaluated the performance of a walking speed estimation system based on using an inertial measurement unit (IMU), a combination of accelerometers and gyroscopes. The walking speed estimation algorithm segments the walking sequence into individual stride cycles (two steps) based on the inverted pendulum-like behaviour of the stance leg during walking and it integrates the angular velocity and linear accelerations of the shank to determine the displacement of each stride. The evaluation was performed in both treadmill and overground walking experiments with various constraints on walking speed, step length and step frequency to provide a relatively comprehensive assessment of the system. Promising results were obtained in providing accurate and consistent walking speed/step length estimation in different walking conditions. An overall percentage root mean squared error (%RMSE) of 4.2 and 4.0% was achieved in treadmill and overground walking experiments, respectively. With an increasing interest in understanding human walking biomechanics, the IMU-based ambulatory system could provide a useful walking speed/step length measurement/control tool for constrained walking studies. PMID:21294007

  9. Critical dimensions for random walks on random-walk chains

    NASA Astrophysics Data System (ADS)

    Rabinovich, Savely; Roman, H. Eduardo; Havlin, Shlomo; Bunde, Armin

    1996-10-01

    The probability distribution of random walks on linear structures generated by random walks in d-dimensional space, Pd(r,t), is analytically studied for the case ??r/t1/4<<1. It is shown to obey the scaling form Pd(r,t)=?(r)t-1/2?-2fd(?), where ?(r)~r2-d is the density of the chain. Expanding fd(?) in powers of ?, we find that there exists an infinite hierarchy of critical dimensions, dc=2,6,10,..., each one characterized by a logarithmic correction in fd(?). Namely, for d=2, f2(?)~=a2?2ln?+b2?2 for 3<=d<=5, fd(?)~=ad?2+bd?d for d=6, f6(?)~=a6?2+b6?6ln? for 7<=d<=9, fd(?)~=ad?2+bd?6+cd?d for d=10, f10(?)~=a10?2+b10?6+c10?10lnj, etc. In particular, for d=2, this implies that the temporal dependence of the probability density of being close to the origin Q2(r,t)?P2(r,t)/?(r)~=t-1/2lnt.

  10. Science Sampler: Walk this way

    NSDL National Science Digital Library

    Jan Fechheim

    2007-02-01

    While they themselves may be in constant motion, getting middle school students to really understand the motion shown in distance/time graphs can often be a challenge--but a challenge that must be taken on! In virtually every listing of national and state science standards for middle school students, the concept of graphically representing motion is included. In the lesson described here, students try to walk along a line marked with distance measurements so that their movement mirrors a given distance/time graph. Depending on the length of the class period, the lesson can be completed in one or two days.

  11. Thermodynamics and entanglements of walks under stress

    Microsoft Academic Search

    E. J. Janse van Rensburg; E. Orlandini; M. C. Tesi; S. G. Whittington

    2009-01-01

    We use rigorous arguments and Monte Carlo simulations to study the thermodynamics and the topological properties of self-avoiding walks on the cubic lattice subjected to an external force f. The walks are anchored at one or both endpoints to an impenetrable plane at Z = 0 and the force is applied in the Z-direction. If a force is applied to

  12. What Changes in Infant Walking and Why.

    ERIC Educational Resources Information Center

    Adolph, Karen E.; Vereijken, Beatrix; Shrout, Patrick E.

    2003-01-01

    Used kinematic measures to compare relative contributions of growing body dimensions, age, and walking experience in walking skill development in 9- to 17-month-olds, kindergartners, and college students. Found that with increased age, size, and experience, children's steps became longer, narrower, straighter, and more consistent, reflecting a…

  13. Biped dynamic walking using reinforcement learning

    Microsoft Academic Search

    Hamid Benbrahim; Judy A. Franklin

    1997-01-01

    This paper presents some results from a study of biped dynamic walking using reinforcement learning. During this study a hardware biped robot was built, a new reinforcement learning algorithm as well as a new learning architecture were developed. The biped learned dynamic walking without any previous knowledge about its dynamic model. The Self Scaling Reinforcement learning algorithm was developed in

  14. Power Demand for Walking on the Treadmill

    NSDL National Science Digital Library

    Gaylord T. Hageseth

    2000-02-01

    This paper presents a mathematical model for walking on the treadmill that calculates the minimum power required for walking on the level at a constant speed and relates it to the pace length. The calculation includes both the horizontal and vertical moti

  15. Learning to walk changes infants’ social interactions

    Microsoft Academic Search

    Melissa W. Clearfield

    2011-01-01

    The onset of crawling marks a motor, cognitive and social milestone. The present study investigated whether independent walking marks a second milestone for social behaviors. In Experiment 1, the social and exploratory behaviors of crawling infants were observed while crawling and in a baby-walker, resulting in no differences based on posture. In Experiment 2, the social behaviors of independently walking

  16. On the concentration of Sinai's walk

    Microsoft Academic Search

    Pierre Andreoletti

    2005-01-01

    We consider Sinai's random walk in random environment. We prove that for an interval of time [1,n] Sinai's walk sojourns in a small neighborhood of the point of localization for the quasi totality of this amount of time. Moreover the local time at the point of localization normalized by $n$ converges in probability to a well defined random variable of

  17. Brownian Optimal Stopping and Random Walks

    SciTech Connect

    Lamberton, D. [Equipe d'Analyse et de Mathematiques Appliquees, Universite de Marne-la-Vallee, 5 Boulevard Descartes, Cite Descartes, Champs-sur-Marne, 77 454 Marne-la-Vallee Cedex 2 (France)], E-mail: dlamb@math.univ-mlv.fr

    2002-06-05

    One way to compute the value function of an optimal stopping problem along Brownian paths consists of approximating Brownian motion by a random walk. We derive error estimates for this type of approximation under various assumptions on the distribution of the approximating random walk.

  18. SLIP PREVENTION IN WALKING - LOWER EXTREMITY BIOMECHANICS

    Microsoft Academic Search

    Daniel Tik-Pui Fongl; Youlian Hong; Jing-Xian U; Kai-Ming Chan

    This study investigated the human slip prevention strategies when walking on slippery surfaces. Fifteen male subjects performed, level walking without slips under sixteen simulated construction site environments. Kinematics, kinetics and electromyography parameters were collected. The slipperiness of the walkway conditions were quantified by the dynamic coefficient of friction (DCOF). Gait changes in slippery condition included prolonged force and pressure exertion

  19. 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…

  20. 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

  1. Path Coalescence in Spatially Correlated Random Walks

    Microsoft Academic Search

    Michael Wilkinson; Bernhard Mehlig

    2003-01-01

    A particle subject to successive, random displacements is said to execute a random walk (in position or some other coordinate). The mathematical properties of random walks have been very thoroughly investigated, and the model is used in many areas of science and engineering as well as other fields such as finance and the life sciences. This letter describes a phenomenon

  2. Swing leg retraction helps biped walking stability

    Microsoft Academic Search

    M. Wisse; C. G. Atkeson; D. K. Kloimwieder

    2005-01-01

    In human walking, the swing leg moves backward just prior to ground contact, i.e. the relative angle between the thighs is decreasing. We hypothesized that this swing leg retraction may have a positive effect on gait stability, because similar effects have been reported in passive dynamic walking models, in running models, and in robot juggling. For this study, we use

  3. Simplest dynamic walking model with toed feet

    Microsoft Academic Search

    R. P. Kumar; J.-W. Yoon; G.-S. Kim

    2008-01-01

    This paper presents a dynamic walking model with toed feet that can walk down a gentle slope under the action of gravity alone. The model is the simplest of its kind with a point mass at the hip and two rigid legs each hinged at the hip on one end and equipped with toed foot at the other end. We

  4. Quantum random walks and decision making.

    PubMed

    Shankar, Karthik H

    2014-01-01

    How realistic is it to adopt a quantum random walk model to account for decisions involving two choices? Here, we discuss the neural plausibility and the effect of initial state and boundary thresholds on such a model and contrast it with various features of the classical random walk model of decision making. PMID:24482330

  5. Symmetric Walking Control: Invariance and Global Stability

    Microsoft Academic Search

    Sang-Ho Hyon; Takashi Emura

    2005-01-01

    This paper first presents a novel control strategy for periodic motion control based on a Hamiltonian system. Ac- cording to the strategy, hybrid symmetric orbits (ideal walking gaits) are explored using reversal symmetry of the Hamiltonian system. Then, an invariance controller, a Symmetric Walking Controller, is derived systematically to distribute the symmetric orbits densely throughout the entire phase space. Finally,

  6. Toe walking in autism: further observations.

    PubMed

    Accardo, Pasquale J; Barrow, William

    2015-04-01

    Toe walking has been associated with language disorders and autism. To better understand the association between persistent toe walking and sensory and motor variables in children with autism, the degree of toe walking was compared with an estimate of the severity of sensory integration dysfunction symptoms and the presence of residual components of the tonic labyrinthine in supine reflex pattern in 61 children younger than 37 months of age with newly diagnosed autism. There was no association between the presence of toe walking and sensory symptoms (P = .5298) or language age (P = .6142), but there was an association between toe walking and the presence of components of the tonic labyrinthine reflex (P = .04222). These preliminary results support the contribution of subtle motor deficits to the evolution of some behaviors associated with autism. PMID:24563477

  7. Quantum walks on a random environment

    SciTech Connect

    Yin Yue; Katsanos, D. E.; Evangelou, S. N. [Department of Physics, University of Ioannina, Ioannina 45110 (Greece)

    2008-02-15

    Quantum walks are considered in a one-dimensional random medium characterized by static or dynamic disorder. Quantum interference for static disorder can lead to Anderson localization which completely hinders the quantum walk and it is contrasted with the decoherence effect of dynamic disorder having strength W, where a quantum to classical crossover at time t{sub c}{proportional_to}W{sup -2} transforms the quantum walk into an ordinary random walk with diffusive spreading. We demonstrate these localization and decoherence phenomena in quantum carpets of the observed time evolution, we relate our results to previously studied models of decoherence for quantum walks, and examine in detail a dimer lattice which corresponds to a single qubit subject to randomness.

  8. 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

  9. Strongly trapped two-dimensional quantum walks

    E-print Network

    Bálint Kollár; Tamás Kiss; Igor Jex

    2015-01-27

    Discrete time quantum walks (DTQWs) are nontrivial generalizations of random walks with a broad scope of applications. In particular, they can be used as computational primitives, and they are suitable tools for simulating other quantum systems. DTQWs usually spread ballistically due to their quantumness. In some cases, however, they can remain localized at their initial state (trapping). The trapping and other fundamental properties of DTQWs are determined by the choice of the coin operator. We introduce and analyze an up to now uncharted type of walks driven by a coin class leading to strong trapping, complementing the known list of walks. This class of walks exhibit a number of exciting properties with the possible applications ranging from light pulse trapping in a medium to topological effects and quantum search.

  10. 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

  11. Interventions to Improve Walking in Older Adults.

    PubMed

    Brach, Jennifer S; Vanswearingen, Jessie M

    2013-12-01

    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

  12. High Point Walking for Health: Creating Built and Social Environments That Support Walking in a Public Housing Community

    PubMed Central

    Rabkin, Janice; Sharify, Denise; Song, Lin

    2009-01-01

    Objectives. We implemented and evaluated multiple interventions to increase walking activity at a multicultural public housing site. Methods. A community-based participatory research partnership and community action teams assessed assets and barriers related to walking and developed multiple interventions to promote walking activity. Interventions included sponsoring walking groups, improving walking routes, providing information about walking options, and advocating for pedestrian safety. A pre–post study design was used to assess the changes in walking activity. Results. Self-reported walking activity increased among walking group participants from 65 to 109 minutes per day (P = .001). The proportion that reported being at least moderately active for at least 150 minutes per week increased from 62% to 81% (P = .018). Conclusions. A multicomponent intervention developed through participatory research methods that emphasized walking groups and included additional strategies to change the built and social environments increased walking activity at a public housing site in Seattle. PMID:19890163

  13. 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 3.63±0.04m verus 2.70±0.21m out of 3.66m; p=0.009), and novices walked further than amputees (1.52±0.20m; p=0.03). Amputees were unable to walk on the narrow-beam, while experts walked further (3.07±0.14m) than novices (1.55±0.26m; 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

  14. Angular momentum of walking at different speeds.

    PubMed

    Bennett, Bradford C; Russell, Shawn D; Sheth, Pradip; Abel, Mark F

    2010-02-01

    Recently, researchers in robotics have used regulation of the angular momentum of body segments about the total body center of mass (CoM) to develop control strategies for bipedal gait. This work was spurred by reports finding that for a "large class" of human movement tasks, including standing, walking, and running the angular momentum is conserved about the CoM. However, there is little data presented to justify this position. This paper describes an analysis of 11 male adults walking overground at 0.7, 1.0, and 1.3 times their comfortable walking speed (CWS). The normalized angular momenta about the body CoM of 12 body segments were computed about all three coordinate axes. The normalized angular momenta were both small (<0.03) and highly regulated for all subjects and walking speed with extrema that negatively correlated with walking speeds. It was found that the angular momentum of the body about its CoM during walking could be described by a small number of principal components. For the adult walkers the first three principal components accounted for more than 97% of the variability of the angular momentum about each of the three principal axes at all walking speeds. In addition, it was found that the orthogonal principal components at each speed and for each subject were similar, i.e., the vectors of the principal components at each speed and for each subject were co-linear. PMID:19889468

  15. 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.

  16. 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

  17. Poincaré-Map-Based Reinforcement Learning For Biped Walking

    Microsoft Academic Search

    Jun Morimoto; Jun Nakanishi; Gen Endo; Gordon Cheng; Christopher G. Atkeson; Garth Zeglin

    2005-01-01

    We propose a model-based reinforcement learn- ing algorithm for biped walking in which the robot learns to appropriately modulate an observed walking pattern. Via- points are detected from the observed walking trajectories using the minimum jerk criterion. The learning algorithm modulates the via-points as control actions to improve walking trajectories. This decision is based on a learned model of the

  18. TRANSIENT NN RANDOM WALK ON THE LINE Endre Cski

    E-print Network

    Foldes, Antonia

    TRANSIENT NN RANDOM WALK ON THE LINE Endre Csáki 1 Alfréd Rényi Institute of Mathematics, Hungarian transient random walk. First, laws of the iterated logarithm are given for the large values of the local. Keywords: transient random walk, local time, strong theorems. Running head: Transient NN random walk. 1

  19. Angular Momentum Regulation during Human Walking: Biomechanics and Control

    E-print Network

    Williams, Brian C.

    : BIOMECHANICS A. Spin Angular Momentum and Resulting Whole Body Angular Excursions during Human WalkingAngular Momentum Regulation during Human Walking: Biomechanics and Control Marko Popovic & Andreas by biomechanical studies on human walking, we present a control strategy for biologically realistic walking based

  20. Why Don't Children Walk To School Anymore?

    Microsoft Academic Search

    Rosanna Taylor

    Did you know that only 12.9% of children currently walk or bike to school? This is down from over 40% in 19691. Even among those who live within one mile of their school, over half of them never walk or bike2. Why is walking to school important? Kids are overweight! Walking to school is a great way to increase physical

  1. Walking pattern modification using manipulability ellipsoid for biped robot

    Microsoft Academic Search

    Thavida Maneewarn; Apinya Boonprakob

    2009-01-01

    This paper suggests the new approach for reducing energy consumption during the walking cycle of the biped robot. After the stable walking trajectory is manually designed, the trajectory can be modified to reduce the energy consumption and increase walking stability based on the measured angular velocities of the robot during the walk combined with the dexterity information from the manipulability

  2. An orbit based control for biomimetic biped walking

    Microsoft Academic Search

    Xiang Luo; Rui Guo; Chi Zhu

    2009-01-01

    One of the main challenges in the control of biped walking is to translate the understanding gained from passive walkers to active systems. In this paper, an active\\/passive hybrid walking control method is studied. Firstly, a two-point walking pattern is proposed according to the structure of human feet and the features of human walking. Secondly, the energy cycle of the

  3. The Staggered Quantum Walk Model

    E-print Network

    R. Portugal; R. A. M. Santos; T. D. Fernandes; D. N. Gonçalves

    2015-06-09

    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.

  4. Quantum walks in curved spacetime

    E-print Network

    Pablo Arrighi; Stefano Facchini; Marcelo Forets

    2015-05-26

    A discrete-time Quantum Walk (QW) is essentially a unitary operator driving the evolution of a single particle on the lattice. Some QWs admit a continuum limit, leading to familiar PDEs (e.g. the Dirac equation), and thus provide us with discrete toy models of familiar particles (e.g. the electron). In this paper, we study the continuum limit of a wide class of QWs, and show that it leads to all those PDEs corresponding to the Hamiltonian form of the massive curved Dirac equation in (1 + 1) dimensions. Therefore a certain QW, which we make explicit, provides us with a unitary discrete toy model of the electron as a test particle in curved spacetime, in spite of the fixed background lattice. Mathematically we have introduced two novel ingredients for taking the continuum limit of a QW, but which apply to any quantum cellular automata: encoding and grouping.

  5. Dynamical continuous time random walk

    NASA Astrophysics Data System (ADS)

    Liu, Jian; Yang, Bo; Chen, Xiaosong; Bao, Jing-Dong

    2015-04-01

    We consider a continuous time random walk model in which each jump is considered to be dynamical process. Dissipative launch velocity and hopping time in each jump is the key factor in this model. Within the model, normal diffusion and anomalous diffusion is realized theoretically and numerically in the force free potential. Besides, external potential can be introduced naturally, so the random walker's behavior in the linear potential and quartic potential is discussed, especially the walker with Lévy velocity in the quartic potential, bimodal behavior of the spatial distribution is observed, it is shown that due to the inertial effect induced by damping term, there exists transition from unimodality to bimodality for the walker's spatial stationary distribution.

  6. Random Walk with Shrinking Steps

    E-print Network

    P. L. Krapivsky; S. Redner

    2003-10-19

    We outline basic properties of a symmetric random walk in one dimension, in which the length of the nth step equals lambda^n, with lambdaoo, the probability that the endpoint is at x, P_{lambda}(x;N), approaches a limiting distribution P_{lambda}(x) that has many beautiful features. For lambda<1/2, the support of P_{lambda}(x) is a Cantor set. For 1/2<=lambda<1, there is a countably infinite set of lambda values for which P_{lambda}(x) is singular, while P_{lambda}(x) is smooth for almost all other lambda values. In the most interesting case of lambda=(sqrt{5}-1)/2=g, P_g(x) is riddled with singularities and is strikingly self-similar. The self-similarity is exploited to derive a simple form for the probability measure M(a,b)= int_a^b P_g(x) dx.

  7. 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.

  8. Localized quantum walks as secured quantum memory

    E-print Network

    C. M. Chandrashekar; Th. Busch

    2015-04-21

    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 occurss 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.

  9. IS THE SUICIDE RATE A RANDOM WALK?

    PubMed

    Yang, Bijou; Lester, David; Lyke, Jennifer; Olsen, Robert

    2015-06-01

    The yearly suicide rates for the period 1933-2010 and the daily suicide numbers for 1990 and 1991 were examined for whether the distribution of difference scores (from year to year and from day to day) fitted a normal distribution, a characteristic of stochastic processes that follow a random walk. If the suicide rate were a random walk, then any disturbance to the suicide rate would have a permanent effect and national suicide prevention efforts would likely fail. The distribution of difference scores from day to day (but not the difference scores from year to year) fitted a normal distribution and, therefore, were consistent with a random walk. PMID:25933046

  10. Decoherence in one-dimensional Quantum Walk

    E-print Network

    Mostafa Annabestani; Seyed Javad Akhtarshenas; Mohamad Reza Abolhassani

    2009-10-11

    In this paper we study decoherence in the quantum walk on the line. We generalize the method of decoherent coin quantum walk, introduced by Brun et al [Phys. Rev. A {\\bf 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.

  11. 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.

  12. Walking cycle recording and analysis for FNS-assisted paraplegic walking

    Microsoft Academic Search

    B. J. Oderberk; G. F. Inbar

    1991-01-01

    In closed-loop functional neuromuscular stimulation (FNS)-assisted paraplegic walking, there is a need for reference leg motion\\u000a trajectories that describe the desired walking cycle. These reference trajectories were defined as the angular changes between\\u000a the leg segments, as measured by an electrogoniometer system. For each leg, the hip, knee and ankle trajectories of normal\\u000a individuals during slow walking were measured and

  13. Texas Society of Professional Engineers FUTURE ENGINEERS 5K RUN/WALK AND 1 MILE FUN WALK/RUN

    E-print Network

    Ward, Karen

    ______________________________ EVENT (circle one) 1 MILE WALK/RUN 5K WALK 5K RUN AGE RACE DAY_____________ SEX__________________ TEAMTexas Society of Professional Engineers Presents FUTURE ENGINEERS 5K RUN/WALK AND 1 MILE FUN WALK/RUN PROCEEDS BENEFIT TSPE EL PASO CHAPTER UTEP Engineering Endowment Scholarship Fund 8:00 A.M. August 20, 2011

  14. 75 FR 185 - Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-04

    ...Part 431 Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In...1904-AB85 Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In...Department of Energy (DOE) is proposing test procedures for measuring the energy...

  15. 75 FR 55067 - Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In Freezers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-09

    ...Part 431 Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In...1904-AB85 Energy Conservation Program: Test Procedures for Walk-In Coolers and Walk-In...notice of proposed rulemaking to adopt test procedures for measuring the energy...

  16. "I'm Just a'-Walking the Dog" correlates of regular dog walking.

    PubMed

    Christian nee Cutt, Hayley; Giles-Corti, Billie; Knuiman, Matthew

    2010-01-01

    Intrapersonal and environmental factors associated with dog walking (N = 483) were examined. A greater proportion of regular (80%) than irregular (59%) dog walkers met the recommended 150 minutes of physical activity per week. Owners who perceived greater social support and motivation from their dogs to walk, and who had access to a dog-supportive park within their neighborhood, were more likely to regularly walk with their dogs, even after adjustment for other well-known correlates of physical activity. The higher level of physical activity of regular dog walkers can be attributed to the additional walking these owners perform with their dogs. PMID:20010004

  17. The hydrodynamics of water-walking arthropods

    E-print Network

    Bush, John W. M.

    We present the results of a combined experimental and theoretical investigation of the dynamics of water-walking insects and spiders. Using high-speed videography, we describe their numerous gaits, some analogous to those ...

  18. Parent Safety Perceptions of Child Walking Routes

    PubMed Central

    Boles, Shawn; Johnson-Shelton, Deb; Schlossberg, Marc; Richey, David

    2014-01-01

    Walking rates to school remain low for U.S. children in large part due to parent concern for child safety. Little research has investigated the specific features of streets and intersection networks that parents associate with safe walking networks for children. To investigate which aspects of the child walking environment lead to parental concern, parent volunteers conducted an audit of streets leading to seven elementary schools in a suburban school district. Parents were most likely to feel concern about streets that lacked sidewalks or had sidewalks with obstructions. Wheelchair-accessible routes were seen as appropriate for walking children. Parents expressed concern over safety at intersections, particularly those involving large streets; traffic controls did not mollify their concern. PMID:25664239

  19. Walking for health in adolescent girls 

    E-print Network

    MacDonald, Mhairi Jane

    2014-07-04

    Research has highlighted that adolescent girls are insufficiently active which has serious implications for their current and future health. Walking is recognised as an effective way of implementing regular, health ...

  20. Gallery Walk Questions about Human Dimensions

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about the human dimensions of geologic issues. The questions are organized ...

  1. Gallery Walk Questions about the Solar System

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about the solar system. The questions are organized according to the ...

  2. Real time visualization of quantum walk

    SciTech Connect

    Miyazaki, Akihide; Hamada, Shinji; Sekino, Hideo [Department of Computer Science and Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka Tenpaku-cho, Toyohashi, 441-8580 Aichi (Japan)

    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.

  3. Asymptotic densities of ballistic Lévy walks

    NASA Astrophysics Data System (ADS)

    Froemberg, D.; Schmiedeberg, M.; Barkai, E.; Zaburdaev, V.

    2015-02-01

    We propose an analytical method to determine the shape of density profiles in the asymptotic long-time limit for a broad class of coupled continuous-time random walks which operate in the ballistic regime. In particular, we show that different scenarios of performing a random-walk step, via making an instantaneous jump penalized by a proper waiting time or via moving with a constant speed, dramatically effect the corresponding propagators, despite the fact that the end points of the steps are identical. Furthermore, if the speed during each step of the random walk is itself a random variable, its distribution gets clearly reflected in the asymptotic density of random walkers. These features are in contrast with more standard nonballistic random walks.

  4. Strongly correlated quantum walks in optical lattices

    NASA Astrophysics Data System (ADS)

    Preiss, Philipp M.; Ma, Ruichao; Tai, M. Eric; Lukin, Alexander; Rispoli, Matthew; Zupancic, Philip; Lahini, Yoav; Islam, Rajibul; Greiner, Markus

    2015-03-01

    Full control over the dynamics of interacting, indistinguishable quantum particles is an important prerequisite for the experimental study of strongly correlated quantum matter and the implementation of high-fidelity quantum information processing. We demonstrate such control over the quantum walk—the quantum mechanical analog of the classical random walk—in the regime where dynamics are dominated by interparticle interactions. Using interacting bosonic atoms in an optical lattice, we directly observed fundamental effects such as the emergence of correlations in two-particle quantum walks, as well as strongly correlated Bloch oscillations in tilted optical lattices. Our approach can be scaled to larger systems, greatly extending the class of problems accessible via quantum walks.

  5. Gallery Walk Questions on Earth's Radiation Balance

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about the Earth's Radiation Balance. The questions are organized ...

  6. Gallery Walk Questions about the Ocean

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about the ocean. The questions are organized according to the cognitive ...

  7. Gallery Walk Questions on Map Reading

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about map reading. The questions are organized according to the cognitive ...

  8. Gallery Walk Questions about the Biosphere

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about the biosphere. The questions are organized according to the cognitive ...

  9. Asymptotic densities of ballistic Lévy walks.

    PubMed

    Froemberg, D; Schmiedeberg, M; Barkai, E; Zaburdaev, V

    2015-02-01

    We propose an analytical method to determine the shape of density profiles in the asymptotic long-time limit for a broad class of coupled continuous-time random walks which operate in the ballistic regime. In particular, we show that different scenarios of performing a random-walk step, via making an instantaneous jump penalized by a proper waiting time or via moving with a constant speed, dramatically effect the corresponding propagators, despite the fact that the end points of the steps are identical. Furthermore, if the speed during each step of the random walk is itself a random variable, its distribution gets clearly reflected in the asymptotic density of random walkers. These features are in contrast with more standard nonballistic random walks. PMID:25768482

  10. Strongly correlated quantum walks in optical lattices.

    PubMed

    Preiss, Philipp M; Ma, Ruichao; Tai, M Eric; Lukin, Alexander; Rispoli, Matthew; Zupancic, Philip; Lahini, Yoav; Islam, Rajibul; Greiner, Markus

    2015-03-13

    Full control over the dynamics of interacting, indistinguishable quantum particles is an important prerequisite for the experimental study of strongly correlated quantum matter and the implementation of high-fidelity quantum information processing. We demonstrate such control over the quantum walk-the quantum mechanical analog of the classical random walk-in the regime where dynamics are dominated by interparticle interactions. Using interacting bosonic atoms in an optical lattice, we directly observed fundamental effects such as the emergence of correlations in two-particle quantum walks, as well as strongly correlated Bloch oscillations in tilted optical lattices. Our approach can be scaled to larger systems, greatly extending the class of problems accessible via quantum walks. PMID:25766229

  11. The random walk model of intrafraction movement

    NASA Astrophysics Data System (ADS)

    Ballhausen, H.; Reiner, M.; Kantz, S.; Belka, C.; Söhn, M.

    2013-04-01

    The purpose of this paper is to understand intrafraction movement as a stochastic process driven by random external forces. The hypothetically proposed three-dimensional random walk model has significant impact on optimal PTV margins and offers a quantitatively correct explanation of experimental findings. Properties of the random walk are calculated from first principles, in particular fraction-average population density distributions for displacements along the principal axes. When substituted into the established optimal margin recipes these fraction-average distributions yield safety margins about 30% smaller as compared to the suggested values from end-of-fraction Gaussian fits. Stylized facts of a random walk are identified in clinical data, such as the increase of the standard deviation of displacements with the square root of time. Least squares errors in the comparison to experimental results are reduced by about 50% when accounting for non-Gaussian corrections from the random walk model.

  12. Stable dynamic walking over uneven terrain

    E-print Network

    Manchester, Ian R.

    We propose a constructive control design for stabilization of non-periodic trajectories of underactuated robots. An important example of such a system is an underactuated “dynamic walking” biped robot traversing rough or ...

  13. Random walk computations of diffusive fields 

    E-print Network

    Lindstrom, Gregory Scot

    1993-01-01

    A numerical study of three problems is carried out using the gradient random walk method. These problems include the heat equation, Fitzhugh-Nagumo equation, and Burgers' equation. Each problem illustrates various aspects of the operation...

  14. MT STROMLO OBSERVATORY VISITOR GUIDE & WALK

    E-print Network

    Botea, Adi

    MT STROMLO OBSERVATORY VISITOR GUIDE & WALK RESEARCH SCHOOL OF ASTRONOMY & ASTROPHYSICS MT STROMLO OBSERVATORY Welcome Mt Stromlo Observatory is the headquarters of The Australian National University's Research School of Astronomy and Astrophysics. The University operates two observatories, Mt Stromlo, west

  15. Mesonic spectroscopy of minimal walking technicolor

    SciTech Connect

    Del Debbio, Luigi [SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Lucini, Biagio; Patella, Agostino [School of Physical Sciences, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Pica, Claudio [CP3-Origins, University of Southern Denmark, Odense, 5230 M (Denmark); Rago, Antonio [Department of Physics, Bergische Universitaet Wuppertal, Gaussstrasse 20, D-42119 Wuppertal (Germany)

    2010-07-01

    We investigate the structure and the novel emerging features of the mesonic nonsinglet spectrum of the minimal walking technicolor theory. Precision measurements in the nonsinglet pseudoscalar and vector channels are compared to the expectations for an IR-conformal field theory and a QCD-like theory. Our results favor a scenario in which minimal walking technicolor is (almost) conformal in the infrared, while spontaneous chiral symmetry breaking seems less plausible.

  16. Design of a bipedal walking robot

    Microsoft Academic Search

    Jerry Pratt; Ben Krupp

    2008-01-01

    We present the mechanical design of a bipedal walking robot named M2V2, as well as control strategies to be implemented for walking and balance recovery. M2V2 has 12 actuated degrees of freedom in the lower body: three at each hip, one at each knee, and two at each ankle. Each degree of freedom is powered by a force controllable Series

  17. Evaluating Walking in Patients with Multiple Sclerosis

    PubMed Central

    Bennett, Susan

    2011-01-01

    Walking limitations are among the most visible manifestations of multiple sclerosis (MS). Regular walking assessments should be a component of patient management and require instruments that are appropriate from the clinician's and the patient's perspectives. This article reviews frequently used instruments to assess walking in patients with MS, with emphasis on their validity, reliability, and practicality in the clinical setting. Relevant articles were identified based on PubMed searches using the following terms: “multiple sclerosis AND (walking OR gait OR mobility OR physical activity) AND (disability evaluation)”; references of relevant articles were also searched. Although many clinician- and patient-driven instruments are available, not all have been validated in MS, and some are not sensitive enough to detect small but clinically important changes. Choosing among these depends on what needs to be measured, psychometric properties, the clinical relevance of results, and practicality with respect to space, time, and patient burden. Of the instruments available, the clinician-observed Timed 25-Foot Walk and patient self-report 12-Item Multiple Sclerosis Walking Scale have properties that make them suitable for routine evaluation of walking performance. The Dynamic Gait Index and the Timed Up and Go test involve other aspects of mobility, including balance. Tests of endurance, such as the 2- or 6-Minute Walk, may provide information on motor fatigue not captured by other tests. Quantitative measurement of gait kinetics and kinematics, and recordings of mobility in the patient's environment via accelerometry or Global Positioning System odometry, are currently not routinely used in the clinical setting. PMID:24453700

  18. 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

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

    PubMed Central

    Gutierrez-Farewik, Elena M.; Bartonek, Åsa; Tedroff, Kristina; Orefelt, Christina; Haglund-Åkerlind, 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 5–13 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 6–12 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

  20. Quantum Search with Multiple Walk Steps per Oracle Query

    E-print Network

    Thomas G. Wong; Andris Ambainis

    2015-04-28

    We identify a key difference between discrete- and continuous-time quantum walks in search, that the former is typically restricted to one walk step per oracle query, whereas the latter can take multiple walk steps per oracle 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 the first example of a greater-than-quadratic speedup for quantum search over its corresponding classical random walk.

  1. Infinite densities for Lévy walks.

    PubMed

    Rebenshtok, A; Denisov, S; Hänggi, P; Barkai, E

    2014-12-01

    Motion of particles in many systems exhibits a mixture between periods of random diffusive-like events and ballistic-like motion. In many cases, such systems exhibit strong anomalous diffusion, where low-order moments ?|x(t)|(q)? with q below a critical value q(c) exhibit diffusive scaling while for q>q(c) a ballistic scaling emerges. The mixed dynamics constitutes a theoretical challenge since it does not fall into a unique category of motion, e.g., the known diffusion equations and central limit theorems fail to describe both aspects. In this paper we resolve this problem by resorting to the concept of infinite density. Using the widely applicable Lévy walk model, we find a general expression for the corresponding non-normalized density which is fully determined by the particles velocity distribution, the anomalous diffusion exponent ?, and the diffusion coefficient K(?). We explain how infinite densities play a central role in the description of dynamics of a large class of physical processes and discuss how they can be evaluated from experimental or numerical data. PMID:25615072

  2. 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.

  3. Predictors of walking capacity in peripheral arterial disease patients

    PubMed Central

    Farah, Breno Quintella; dos Anjos Souza Barbosa, João Paulo; Cucato, Gabriel Grizzo; da Rocha Chehuen, Marcel; Gobbo, Luis Alberto; Wolosker, Nelson; de Moraes Forjaz, Cláudia Lúcia; Dias, Raphael Mendes Ritti-

    2013-01-01

    OBJECTIVE: To estimate walking capacity in intermittent claudication patients through a prediction model based on clinical characteristics and the walking impairment questionnaire. METHODS: The sample included 133 intermittent claudication patients of both genders aged between 30 and 80 years. Data regarding clinical characteristics, the walking impairment questionnaire and treadmill walking test performance were obtained. Multiple regression modeling was conducted to predict claudication onset distance and total walking distance using clinical characteristics (age, height, mass, body mass index, ankle brachial index lower, gender, history of smoking and co-morbid conditions) and walking impairment questionnaire responses. Comparisons of claudication onset distance and total walking distance measured during treadmill tests and estimated by a regression equation were performed using paired t-tests. RESULTS: Co-morbid conditions (diabetes and coronary artery disease) and questions related to difficulty in walking short distances (walking indoors – such as around your house and walking 5 blocks) and at low speed (walking 1 block at average speed – usual pace) resulted in the development of new prediction models high significant for claudication onset distance and total walking distance (p<0.001). In addition, non-significant differences from the results obtained by the treadmill test and estimated by the current model (p>0.05) were observed. CONCLUSION: The current study demonstrated that walking capacity can be adequately estimated based on co-morbid conditions and responses to the walking impairment questionnaire. PMID:23778336

  4. Design of a quadruped walking vehicle for dynamic walking and stair climbing

    Microsoft Academic Search

    Shigeo Hirose; Kan Yoneda; Kazuhiko Arai; Tomoyoshi Ibe

    1994-01-01

    This paper discusses the design of a quadruped walking vehicle for walking dynamically at high speed and climbing ordinary stairs (30-40°). To realize these requests, new mechanisms are introduced, which are (1) a prismatic joint leg that does not interfere with the steps of a staircase and which performs a cylindrical coordinate motion with good energy efficiency, (2) an articulated

  5. Yet another humanoid walking - passive dynamic walking with torso under simple control

    Microsoft Academic Search

    Masaki Haruna; Masaki Ogino; Koh Hosoda; Minoru Asada

    2001-01-01

    Passive dynamic walking (PDW) has received an increasing attention as a simple walking method with no or very little control, thus requiring a small amount of energy consumption. To the best of our knowledge, there are no PDW models with a torso although there have already been many studies on PDW. This paper presents the first step towards applying the

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

    SciTech Connect

    Dimcovic, Zlatko [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States); Rockwell, Daniel; Milligan, Ian; Burton, Robert M.; Kovchegov, Yevgeniy [Department of Mathematics, Oregon State University, Corvallis, Oregon 97331 (United States); Nguyen, Thinh [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331 (United States)

    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.

  7. A marching-walking hybrid induces step length adaptation and transfers to natural walking.

    PubMed

    Long, Andrew W; Finley, James M; Bastian, Amy J

    2015-06-01

    Walking is highly adaptable to new demands and environments. We have previously studied adaptation of locomotor patterns via a split-belt treadmill, where subjects learn to walk with one foot moving faster than the other. Subjects learn to adapt their walking pattern by changing the location (spatial) and time (temporal) of foot placement. Here we asked whether we can induce adaptation of a specific walking pattern when one limb does not "walk" but instead marches in place (i.e., marching-walking hybrid). The marching leg's movement is limited during the stance phase, and thus certain sensory signals important for walking may be reduced. We hypothesized that this would produce a spatial-temporal strategy different from that of normal split-belt adaptation. Healthy subjects performed two experiments to determine whether they could adapt their spatial-temporal pattern of step lengths during the marching-walking hybrid and whether the learning transfers to over ground walking. Results showed that the hybrid group did adapt their step lengths, but the time course of adaptation and deadaption was slower than that for the split-belt group. We also observed that the hybrid group utilized a mostly spatial strategy whereas the split-belt group utilized both spatial and temporal strategies. Surprisingly, we found no significant difference between the hybrid and split-belt groups in over ground transfer. Moreover, the hybrid group retained more of the learned pattern when they returned to the treadmill. These findings suggest that physical rehabilitation with this marching-walking paradigm on conventional treadmills may produce changes in symmetry comparable to what is observed during split-belt training. PMID:25867742

  8. Renormalization and scaling in quantum walks

    NASA Astrophysics Data System (ADS)

    Boettcher, Stefan; Falkner, Stefan; Portugal, Renato

    2014-09-01

    We show how to extract the scaling behavior of quantum walks using the renormalization group (RG). We introduce the method by efficiently reproducing well-known results on the one-dimensional lattice. For a nontrivial model, we apply this method to the dual Sierpinski gasket and obtain its exact, closed system of RG recursions. Numerical iteration suggests that under rescaling the system length, L'=2L, characteristic times rescale as t'=2dwt, with the exact walk exponent dw=log2?5 =1.1609... Despite the lack of translational invariance, this value is very close to the ballistic spreading, dw=1, found for regular lattices. However, we argue that an extended interpretation of the traditional RG formalism will be needed to obtain scaling exponents analytically. Direct simulations confirm our RG prediction for dw and furthermore reveal an immensely rich phenomenology for the spreading of the quantum walk on the gasket. Invariably, quantum interference localizes the walk completely, with a site-access probability that decreases with a power law from the initial site, in contrast to a classical random walk, which would pass all sites with certainty.

  9. Renormalization and Scaling in Quantum Walks

    E-print Network

    S. Boettcher; S. Falkner; R. Portugal

    2014-09-28

    We show how to extract the scaling behavior of quantum walks using the renormalization group (RG). We introduce the method by efficiently reproducing well-known results on the one-dimensional lattice. As a nontrivial model, we apply this method to the dual Sierpinski gasket and obtain its exact, closed system of RG-recursions. Numerical iteration suggests that under rescaling the system length, $L^{\\prime}=2L$, characteristic times rescale as $t^{\\prime}=2^{d_{w}}t$ with the exact walk exponent $d_{w}=\\log_{2}\\sqrt{5}=1.1609\\ldots$. Despite the lack of translational invariance, this is very close to the ballistic spreading, $d_{w}=1$, found for regular lattices. However, we argue that an extended interpretation of the traditional RG formalism will be needed to obtain scaling exponents analytically. Direct simulations confirm our RG-prediction for $d_w$ and furthermore reveal an immensely rich phenomenology for the spreading of the quantum walk on the gasket. Invariably, quantum interference localizes the walk completely with a site-access probability that declines with a powerlaw from the initial site, in contrast with a classical random walk, which would pass all sites with certainty.

  10. Quantum random-walk search algorithm

    SciTech Connect

    Shenvi, Neil; Whaley, K. Birgitta [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Kempe, Julia [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Computer Science Division, EECS, University of California, Berkeley, California 94720 (United States); CNRS-LRI, UMR 8623, Universite de Paris-Sud, 91405 Orsay (France)

    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.

  11. Steering random walks with kicked ultracold atoms

    E-print Network

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

    2015-06-27

    A 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 to steer such a random walk 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 L\\'evy 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.

  12. Design of a bipedal walking robot

    NASA Astrophysics Data System (ADS)

    Pratt, Jerry; Krupp, Ben

    2008-04-01

    We present the mechanical design of a bipedal walking robot named M2V2, as well as control strategies to be implemented for walking and balance recovery. M2V2 has 12 actuated degrees of freedom in the lower body: three at each hip, one at each knee, and two at each ankle. Each degree of freedom is powered by a force controllable Series Elastic Actuator. These actuators provide high force fidelity and low impedance, allowing for control techniques that exploit the natural dynamics of the robot. The walking and balance recovery controllers will use the concepts of Capture Points and the Capture Region in order to decide where to step. A Capture Point is a point on the ground in which a biped can step to in order to stop, and the Capture Region is the locus of such points.

  13. CDC Vital Signs: More People Walk to Better Health

    MedlinePLUS

    ... exercise, or for activities such as walking the dog. The percentage of people who report walking at ... risk for heart disease, stroke, type 2 diabetes, depression, and some cancers. Improving spaces and having safe ...

  14. 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

  15. Interventions to promote walking: systematic review

    PubMed Central

    Foster, Charles E; Rothnie, Helen; Cavill, Nick; Hamilton, Val; Fitzsimons, Claire F; Mutrie, Nanette

    2007-01-01

    Objective To assess the effects of interventions to promote walking in individuals and populations. Design Systematic review. Data sources Published and unpublished reports in any language identified by searching 25 electronic databases, by searching websites, reference lists, and existing systematic reviews, and by contacting experts. Review methods Systematic search for and appraisal of controlled before and after studies of the effects of any type of intervention on how much people walk, the distribution of effects on walking between social groups, and any associated effects on overall physical activity, fitness, risk factors for disease, health, and wellbeing. Results We included 19 randomised controlled trials and 29 non-randomised controlled studies. Interventions tailored to people's needs, targeted at the most sedentary or at those most motivated to change, and delivered either at the level of the individual (brief advice, supported use of pedometers, telecommunications) or household (individualised marketing) or through groups, can encourage people to walk more, although the sustainability, generalisability, and clinical benefits of many of these approaches are uncertain. Evidence for the effectiveness of interventions applied to workplaces, schools, communities, or areas typically depends on isolated studies or subgroup analysis. Conclusions The most successful interventions could increase walking among targeted participants by up to 30-60 minutes a week on average, at least in the short term. From a perspective of improving population health, much of the research currently provides evidence of efficacy rather than effectiveness. Nevertheless, interventions to promote walking could contribute substantially towards increasing the activity levels of the most sedentary. PMID:17540909

  16. Environmental perceptions and objective walking trail audits inform a community-based participatory research walking intervention

    PubMed Central

    2012-01-01

    Background Given the documented physical activity disparities that exist among low-income minority communities and the increased focused on socio-ecological approaches to address physical inactivity, efforts aimed at understanding the built environment to support physical activity are needed. This community-based participatory research (CBPR) project investigates walking trails perceptions in a high minority southern community and objectively examines walking trails. The primary aim is to explore if perceived and objective audit variables predict meeting recommendations for walking and physical activity, MET/minutes/week of physical activity, and frequency of trail use. Methods A proportional sampling plan was used to survey community residents in this cross-sectional study. Previously validated instruments were pilot tested and appropriately adapted and included the short version of the validated International Physical Activity Questionnaire, trail use, and perceptions of walking trails. Walking trails were assessed using the valid and reliable Path Environmental Audit Tool which assesses four content areas including: design features, amenities, maintenance, and pedestrian safety from traffic. Analyses included Chi-square, one-way ANOVA's, multiple linear regression, and multiple logistic models. Results Numerous (n = 21) high quality walking trails were available. Across trails, there were very few indicators of incivilities and safety features rated relatively high. Among the 372 respondents, trail use significantly predicted meeting recommendations for walking and physical activity, and MET/minutes/week. While controlling for other variables, significant predictors of trail use included proximity to trails, as well as perceptions of walking trail safety, trail amenities, and neighborhood pedestrian safety. Furthermore, while controlling for education, gender, and income; for every one time per week increase in using walking trails, the odds for meeting walking recommendations increased 1.27 times, and the odds for meeting PA recommendation increased 3.54 times. Perceived and objective audit variables did not predict meeting physical activity recommendations. Conclusions To improve physical activity levels, intervention efforts are needed to maximize the use of existing trails, as well as improve residents' perceptions related to incivilities, safety, conditions of trail, and amenities of the walking trails. This study provides important insights for informing development of the CBPR walking intervention and informing local recreational and environmental policies in this southern community. PMID:22289653

  17. Comparison of treadmill and over-ground Nordic walking

    Microsoft Academic Search

    Gail Dechman; Jennifer Appleby; Mike Carr; Melanie Haire

    2012-01-01

    The purpose of this study was to compare the physiological responses of Nordic walking on a specially designed treadmill and Nordic walking on a level over-ground surface. Thirteen participants completed three 1-h Nordic walking training sessions. Following the training sessions, each participant performed two 1600-m over-ground Nordic walking trials at a self-selected pace. Each participant then completed two 1600-m Nordic

  18. Comparison of treadmill and over-ground Nordic walking

    Microsoft Academic Search

    Gail Dechman; Jennifer Appleby; Mike Carr; Melanie Haire

    2011-01-01

    The purpose of this study was to compare the physiological responses of Nordic walking on a specially designed treadmill and Nordic walking on a level over-ground surface. Thirteen participants completed three 1-h Nordic walking training sessions. Following the training sessions, each participant performed two 1600-m over-ground Nordic walking trials at a self-selected pace. Each participant then completed two 1600-m Nordic

  19. Walking speed over 10 metres overestimates locomotor capacity after stroke

    Microsoft Academic Search

    Catherine M Dean; Carol L. Richards; Francine Malouin

    2001-01-01

    Objective: To examine 10-m comfortable walking speed and 6-minute distance in healthy individuals and individuals after stroke and to assess the level of disability associated with poor walking endurance after stroke.Design: Descriptive study in which comfortable walking speed over 10 m and distance covered in 6 minutes (6-minute walk test) were compared between healthy subjects and subjects after stroke.Subjects: Twelve

  20. Self-Attractive Random Walks: The Case of Critical Drifts

    E-print Network

    Ioffe, Dmitry

    2011-01-01

    Self-attractive random walks undergo a phase transition in terms of the applied drift: If the drift is strong enough, then the walk is ballistic, whereas in the case of small drifts self-attraction wins and the walk is sub-ballistic. We show that, in any dimension at least 2, this transition is of first order. In fact, we prove that the walk is already ballistic at critical drifts, and establish the corresponding LLN and CLT.

  1. 7.RP Walk-a-thon 2

    NSDL National Science Digital Library

    This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Julianna participated in a walk-a-thon to raise money for cancer research. She recorded the total distance she walked at several different points in ti...

  2. 6.RP Walk-a-thon 1

    NSDL National Science Digital Library

    This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Julianna participated in a walk-a-thon to raise money for cancer research. She recorded the total distance she walked at several different points in ti...

  3. Quantum Random Walks with General Particle States

    NASA Astrophysics Data System (ADS)

    Belton, Alexander C. R.

    2014-06-01

    A convergence theorem is obtained for quantum random walks with particles in an arbitrary normal state. This unifies and extends previous work on repeated-interactions models, including that of Attal and Pautrat (Ann Henri Poincaré 7:59-104 2006) and Belton (J Lond Math Soc 81:412-434, 2010; Commun Math Phys 300:317-329, 2010). When the random-walk generator acts by ampliation and either multiplication or conjugation by a unitary operator, it is shown that the quantum stochastic cocycle which arises in the limit is driven by a unitary process.

  4. Modified discrete random walk with absorption

    E-print Network

    Theo van Uem

    2009-03-02

    We obtain expected number of arrivals, probability of arrival, absorption probabilities and expected time before absorption for a modified discrete random walk on the (sub)set of integers. In a [pqrs] random walk the particle can move one step forward or backward, stay for a moment in the same state or it can be absorbed immediately in the current state. M[pqrs] is a modified version, where probabilities on both sides of a multiple function barrier M are of different [pqrs] type.

  5. Quantum Persistence: A Random Walk Scenario

    E-print Network

    Sanchari Goswami; Parongama Sen; Arnab Das

    2010-01-28

    In this paper we extend the concept of persistence, well defined for classical stochastic dynamics, to the context of quantum dynamics. We demonstrate the idea via quantum random walk and a successive measurement scheme, where persistence is defined as the time during which a given site remains unvisited by the walker. We also investigated the behavior of related quantities, e.g., the first-passage time and the succession probability (newly defined), etc. The study reveals power law scaling behavior of these quantities with new exponents. Comparable features of the classical and the quantum walks are discussed.

  6. Learning to Walk in 20 Minutes Russ Tedrake

    E-print Network

    Tedrake, Russ

    Learning to Walk in 20 Minutes Russ Tedrake Brain & Cognitive Sciences Center for Bits and Atoms, or robustness[7]. Dynamic walking is an excellent problem for studying learning control. Trial and error of a difficult learning problem. First, walking robots typically have many degrees of freedom, which can cause

  7. Modeling and Learning Walking Gaits of Biped Robots

    E-print Network

    Menegatti, Emanuele

    Modeling and Learning Walking Gaits of Biped Robots Matthias Hebbel, Ralf Kosse and Walter Nistico in the simulator. Finally, we present the results of a walk learning experiment which was done on a real robot. For these experiments we have developed a system which allows the robot to learn to walk fully autonomously. II

  8. A Simple Reinforcement Learning Algorithm For Biped Walking

    E-print Network

    Atkeson, Christopher G.

    A Simple Reinforcement Learning Algorithm For Biped Walking Jun Morimoto, Gordon Cheng, Department propose a model-based reinforcement learning algorithm for biped walking in which the robot learns walking. Our algorithm has two elements, learning appropriate foot placement, and estimating appropriate

  9. Control of Physicallybased Simulated Walking Joseph F. Laszlo

    E-print Network

    Toronto, University of

    or simulate. We easily forget the time we ourselves have spent as toddlers learning how to walk, runControl of Physically­based Simulated Walking Joseph F. Laszlo Michiel van de Panne Eugene Fiume Department of Computer Science University of Toronto 1 Abstract Walking is a deceptively simple behaviour

  10. Learning from Labeled and Unlabeled Data Using Random Walks

    E-print Network

    Learning from Labeled and Unlabeled Data Using Random Walks Dengyong Zhou and Bernhard Sch-supervised learning, random walks, regularization, spectral graph theory. 1. Introduction We consider the general the supervised learning methods (Zhou et al., 2004). Here we further investigate the algorithm using random walks

  11. Stilt walking: How do we learn those first steps?

    Microsoft Academic Search

    Sakineh B. Akram; James S. Frank

    2009-01-01

    This study examined how young healthy adults learn stilt walking. Ten healthy male university students attended two sessions of testing held on two consecutive days. In each session participants performed three blocks of 10 stilt-walking trials. Angular movements of head and trunk and the spatial and temporal gait parameters were recorded. When walking on stilts young adults improved their gait

  12. Reinforcement Learning Control for Biped Robot Walking on Uneven Surfaces

    E-print Network

    Reinforcement Learning Control for Biped Robot Walking on Uneven Surfaces Shouyi Wang, Jelmer investigate the use of reinforcement learning to make a dynamic walking robot more robust against ground robots (such as the Asimo robot by Honda). To enhance the robustness of dynamic walking, learning control

  13. Upper limits of Sinai's walk in random scenery

    Microsoft Academic Search

    Olivier Zindy

    2007-01-01

    Summary. We consider Sinai's walk in i.i.d. random scenery and focus our attention on a conjecture of Revesz concerning the upper limits of Sinai's walk in random scenery when the scenery is bounded from above. A close study of the competition between the concentration property for Sinai's walk and negative values for the scenery enables us to prove that the

  14. Graph Walks and Graphical Models William W. Cohen

    E-print Network

    Cohen, William W.

    Graph Walks and Graphical Models William W. Cohen March 2010 CMU-ML-10-102 #12;#12;Graph Walks University Pittsburgh, PA 15213 School of Computer Science, Machine Learning Department, Carnegie MellonRank, random walk with restart, graph similarity #12;Abstract Inference in Markov random fields

  15. NON-PERTURBATIVE APPROACH TO RANDOM WALK IN MARKOVIAN ENVIRONMENT.

    E-print Network

    Liverani, Carlangelo

    NON-PERTURBATIVE APPROACH TO RANDOM WALK IN MARKOVIAN ENVIRONMENT. DMITRY DOLGOPYAT AND CARLANGELO LIVERANI Abstract. We prove the CLT for a random walk in a dynamical environment where the states of the environment at different sites are independent Markov chains. 1. Introduction The study of random walk

  16. Walking and the Preservation of Cognitive Function in Older Populations

    ERIC Educational Resources Information Center

    Prohaska, Thomas R.; Eisenstein, Amy R.; Satariano, William A.; Hunter, Rebecca; Bayles, Constance M.; Kurtovich, Elaine; Kealey, Melissa; Ivey, Susan L.

    2009-01-01

    Purpose: This cross-sectional study takes a unique look at the association between patterns of walking and cognitive functioning by examining whether older adults with mild cognitive impairment differ in terms of the community settings where they walk and the frequency, intensity, or duration of walking. Design and Methods: The sample was based on…

  17. Random Walks on Random Graphs Colin Cooper1

    E-print Network

    Cooper, Colin

    of the notions and applications of random walks on finite graphs, especially as they apply to random graphs problem is via random walk. Let denote the set of all proper k colourings of G. This will most likelyRandom Walks on Random Graphs Colin Cooper1 and Alan Frieze2 1 Department of Computer Science, King

  18. ON MIXING OF CERTAIN RANDOM WALKS, CUTOFF PHENOMENON AND SHARP

    E-print Network

    Vu, Van H.

    are certain random walks on vector spaces over finite fields. We show that the behavior of such walks is given G be a finite group, and let S be a set of generators of G. Consider a Markov chain Xt on G which introduce a notion of a geometric random walk. Let V = Fn q be an abelian group of vectors in a finite

  19. A humanoid mini-walking robot with a stick

    Microsoft Academic Search

    Fuliang Le; Xinyu Wu; Shiqi Yu; Bin Zhang; Yangsheng Xu

    2009-01-01

    This paper describes a compact mini-walking robot with Barbie's shape, and its walking is realized with only one actuator. The first remarkable feature of this robot is the total weight and dimension of the proposed mechanism is expected to be lighter and smaller than other mini-walking robots. Secondly, the proposed leg mechanism in the robot can work smoothly as human

  20. TRANSIENT NEAREST NEIGHBOR RANDOM WALK AND BESSEL PROCESS

    E-print Network

    Csáki, Endre

    TRANSIENT NEAREST NEIGHBOR RANDOM WALK AND BESSEL PROCESS Endre Csáki 1 Alfréd Rényi Institute a transient Bessel process and a certain nearest neighbor (NN) random walk that is constructed from the former;cation: Primary 60F17; Secondary 60F15, 60J10, 60J55, 60J60. Keywords: transient random walk, Bessel

  1. TRANSIENT NEAREST NEIGHBOR RANDOM WALK AND BESSEL PROCESS

    E-print Network

    Foldes, Antonia

    TRANSIENT NEAREST NEIGHBOR RANDOM WALK AND BESSEL PROCESS Endre Csáki 1 Alfréd Rényi Institute a transient Bessel process and a certain nearest neighbor (NN) random walk that is constructed from the former, 60J10, 60J55, 60J60. Keywords: transient random walk, Bessel process, strong invariance principle

  2. Integer Addition and Subtraction: Walking the Number Line (2)

    NSDL National Science Digital Library

    EDC in Maine

    2012-01-01

    This Java applet, an adaption of "Integer Addition and Subtraction: Walking the Number Line" (cataloged separately) models the addition and subtraction of integers of example expressions by walking a character along a number line. A slider changes the example expression and the check boxes show or can hide the character's walking trail, hints and solutions for the example expressions.

  3. HUMANOID ROBOT WALKING TRAJECTORY GENERATION AND HYBRID CONTROL

    Microsoft Academic Search

    Ozan Ayhan; Kemalettin Erbatur

    Past three decades witnessed a growing interest in biped walking robots because of their advantageous use in the human environment. However, their control is challenging because of their many DOFs and nonlinearities in their dynamics. Various trajector y generation and walking control approaches ranging f rom open loop walking to systems with many sensors and feedback loops have been reported

  4. Coordination in CPG and its Application on Bipedal Walking

    Microsoft Academic Search

    Weiwei Huang; Chee-meng Chew; Geok-soon Hong

    2008-01-01

    Research of bipedal walking has been motivated by its great flexible in rough terrain walking, as well as its benefits to prosthesis development. This paper aims to achieve coordination of central pattern generator (CPG) and asymptotically stable walking behavior. CPG is always referred as several oscillators with coupled mutual inhibition. In this paper, the oscillator model proposed by Matsuoka was

  5. Random Walks, Interacting Particles, Dynamic Networks: Randomness Can Be Helpful

    Microsoft Academic Search

    Colin Cooper

    \\u000a The aim of this article is to discuss some applications of random processes in searching and reaching consensus on finite\\u000a graphs. The topics covered are: Why random walks?, Speeding up random walks, Random and deterministic walks, Interacting particles\\u000a and voting, Searching changing graphs.

  6. 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…

  7. Vision-Based Walking Parameter Estimation for Biped Locomotion Imitation

    Microsoft Academic Search

    Juan Pedro Bandera Rubio; Changjiu Zhou; Francisco Sandoval Hernández

    2005-01-01

    This paper proposes a new vision-based system that can ex- tract walking parameters from human demonstration. The system uses only a non-calibrated USB webcam connected to a standard PC, and the human is only required to put three color patches on one of his legs and walk roughly in a perpendicular plane with respect to camera ori- entation. The walking

  8. Human walking capture and its inspiration to biped gait planning

    Microsoft Academic Search

    Zeyang Xia; Guodong Chen; Zhenzhong Jia; Jing Xiong; K. Chen

    2009-01-01

    Existing approaches to biped gait generation always need to assume appropriate parameter conditions of the walking patterns. To accomplish this, this paper aims to experimentally investigate the characteristics of the human walking, and reveal, to some extent, its balance strategies. The experimental study was carried out on a self-designed human walking testing platform, which captures the joint kinematics data and

  9. Using built environment characteristics to predict walking for exercise

    Microsoft Academic Search

    Gina S Lovasi; Anne V Moudon; Amber L Pearson; Philip M Hurvitz; Eric B Larson; David S Siscovick; Ethan M Berke; Thomas Lumley; Bruce M Psaty

    2008-01-01

    BACKGROUND: Environments conducive to walking may help people avoid sedentary lifestyles and associated diseases. Recent studies developed walkability models combining several built environment characteristics to optimally predict walking. Developing and testing such models with the same data could lead to overestimating one's ability to predict walking in an independent sample of the population. More accurate estimates of model fit can

  10. Continuous-Time Quantum Walks on the Symmetric Group

    Microsoft Academic Search

    Heath Gerhardt; John Watrous

    2003-01-01

    In this paper we study continuous-time quantum walks on Cayley graphs of the symmetric group, and prove various facts concerning such walks that demonstrate significant differences from their classical analogues. In particular, we show that for several natural choices for gener- ating sets, these quantum walks do not have uniform limiting distributions, and are effectively blind to large areas of

  11. Compliant leg behaviour explains basic dynamics of walking and running

    E-print Network

    Compliant leg behaviour explains basic dynamics of walking and running Hartmut Geyer1,*, Andre in walking and rebounding on compliant legs in running. However, while rebounding legs well explain­mass model, we show that not stiff but compliant legs are essential to obtain the basic walking mechanics

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

    SciTech Connect

    Hillery, Mark [Department of Physics, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10021 (United States); Reitzner, Daniel; Buzek, Vladimir [Research Center for Quantum Information, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

    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.

  13. WalkSafe: A Pedestrian Safety App for Mobile Phone Users Who Walk and Talk While Crossing Roads

    E-print Network

    Torresani, Lorenzo

    WalkSafe: A Pedestrian Safety App for Mobile Phone Users Who Walk and Talk While Crossing Roads distract users, presenting a significant impact to pedestrian safety; for example, a mobile phone user deep, improving the safety of pedestrian mobile phone users. WalkSafe uses the back camera of the mobile phone

  14. A comparison of at-home walking and 10-meter walking test parameters of individuals with post-stroke hemiparesis.

    PubMed

    Nagano, Katsuhito; Hori, Hideaki; Muramatsu, Ken

    2015-02-01

    [Purpose] The purpose of this study was to clarify the difference in gait parameters of at-home walking and the 10-meter walking test results of individuals with hemiparesis. [Subjects] A total of 14 hemiparetic stroke recovery patients participated in this study. Inclusion criteria were: living at home, the ability to walk independently, and demonstrated low extremity on recovery stages III-V on the Brunnstrom Approach. The average age of the subjects was 66?years. [Methods] We used video surveillance and the inked footprint technique to record usual walking speed and maximum speed patterns both in subjects' homes and during the 10-meter walking test. From these methods, walking speed, stride length, and step rate were calculated. [Results] While both usual and maximum walking speeds of the 10-meter walking test correlated with stride length and step rate, at-home walking speeds only significantly correlated with stride length. [Conclusion] Walking patterns of the 10-meter walking test are quantifiably distinct from those demonstrated in patients' homes, and this difference is mainly characterized by stride length. In order to enhance in-home walking ability, exercises that improve length of stride rather than step rate should be recommended. PMID:25729167

  15. 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…

  16. FOOT PLACEMENT IN A BODY REFERENCE FRAME DURING WALKING AND ITS RELATIONSHIP TO HEMIPARETIC WALKING PERFORMANCE

    PubMed Central

    Balasubramanian, Chitralakshmi K.; Neptune, Richard R.; Kautz, Steven A.

    2010-01-01

    Background Foot placement during walking is closely linked to the body position, yet it is typically quantified relative to the other foot. The purpose of this study was to quantify foot placement patterns relative to body post-stroke and investigate its relationship to hemiparetic walking performance. Methods Thirty-nine participants with hemiparesis walked on a split-belt treadmill at their self-selected speeds and twenty healthy participants walked at matched slow speeds. Anterior-posterior and medial-lateral foot placements (foot center-of-mass) relative to body (pelvis center-of-mass) quantified stepping in body reference frame. Walking performance was quantified using step length asymmetry ratio, percent of paretic propulsion and paretic weight support. Findings Participants with hemiparesis placed their paretic foot further anterior than posterior during walking compared to controls walking at matched slow speeds (p < .05). Participants also placed their paretic foot further lateral relative to pelvis than non-paretic (p < .05). Anterior-posterior asymmetry correlated with step length asymmetry and percent paretic propulsion but some persons revealed differing asymmetry patterns in the translating reference frame. Lateral foot placement asymmetry correlated with paretic weight support (r = .596; p < .001), whereas step widths showed no relation to paretic weight support. Interpretation Post-stroke gait is asymmetric when quantifying foot placement in a body reference frame and this asymmetry related to the hemiparetic walking performance and explained motor control mechanisms beyond those explained by step lengths and step widths alone. We suggest that biomechanical analyses quantifying stepping performance in impaired populations should investigate foot placement in a body reference frame. PMID:20193972

  17. New Results for Random Walk Learning

    Microsoft Academic Search

    Jeffrey C. Jackson; Karl Wimmer

    2009-01-01

    In a very strong positive result for passive learn- ing algorithms, Bshouty et al. showed that DNF expressions are efficiently learnable in the uni- form random walk model. It is natural to ask whether the more expressive class of thresh- olds of parities (TOP) is similarly learnable, but the Bshouty et al. time bound becomes exponential in this case. We

  18. Visual learning in walking blowflies, Lucilia cuprina

    Microsoft Academic Search

    Tsukasa Fukushi

    1985-01-01

    Summary The Australian sheep blowfliesLucilia cuprina were trained by presenting droplets of sugar solution on a light spot of blue (460 nm wavelength) or green (520 nm wavelength). During the test, the searching behaviour was elicited by sugar stimulation. Then, the flies were allowed to walk in the arena where four coloured spots (two blue and two green) with light

  19. On Exact Learning from Random Walk

    Microsoft Academic Search

    Nader H. Bshouty; Iddo Bentov

    2006-01-01

    We consider a few particular exact learning models based on a random walk stochas- tic process, and thus more restricted than the well known general exact learning models. We give positive and negative results as to whether learning in these particular models is easier than in the general learning models.

  20. Learning to Walk in 20 Minutes

    Microsoft Academic Search

    Russ Tedrake; H. Sebastian Seung

    2005-01-01

    ó We present a statistical gradient following algo- rithm which optimizes a control policy for bipedal walking online on a real robot. One of the distinguishing features of this system is that learning and execution occur simultaneously: there are no explicit learning trials and there is no need to model the dynamics of the robot in a simulation. Thanks in

  1. Learning energy efficient walking based on ballistics

    Microsoft Academic Search

    Masaki Oginol; Koh Hosoda; Minoru Asada

    2003-01-01

    This paper presents a method to realize energy efficient walking of a biped robot with a layered controller. The lower layer controller is a state machine which consists of four states: (1) constant torque is applied to hip and knee joints of the swing leg. (2) no torque is applied so that the swing leg can move in a ballistic

  2. Resolving Identity Uncertainty with Learned Random Walks

    Microsoft Academic Search

    Ted Sandler; Lyle H. Ungar; Koby Crammer

    2009-01-01

    A pervasive problem in large relational databases is identity uncertainty which occurs when multiple entries in a database refer to the same underlying entity in the world. Relational databases exhibit rich graphical structure and are naturally modeled as graphs whose nodes represent entities and whose typed-edges represent relations between them. We propose using random walk models for resolving identity uncertainty

  3. Learning to Walk Structured Text Networks

    Microsoft Academic Search

    Einat Minkov; William W. Cohen

    2008-01-01

    Abstract We propose representing a text corpus as a labeled directed graph, where nodes represent words and weighted edges represent the syntactic relations between them, as derived by dependency parsing. Given this graph, we adopt a graph-based similarity measure based on random walks to derive a similarity measure between words, and also use supervised learning to improve the derived similarity

  4. 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.

  5. 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...

  6. Moments of Coinless Quantum Walks on Lattices

    E-print Network

    Raqueline A. M. Santos; Renato Portugal; Stefan Boettcher

    2015-02-23

    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. 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.

  7. Measurements in the Levy quantum walk

    SciTech Connect

    Romanelli, A. [Instituto de Fisica, Facultad de Ingenieria, Universidad de la Republica, Casilla de correo 30, Codigo Postal 11000, Montevideo (Uruguay)

    2007-11-15

    We study the quantum walk subjected to measurements with a Levy waiting-time distribution. We find that the system has a sub-ballistic behavior instead of a diffusive one. We obtain an analytical expression for the exponent of the power law of the variance as a function of the characteristic parameter of the Levy distribution.

  8. 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

  9. Walking to School: Taking Research to Practice

    ERIC Educational Resources Information Center

    Heelan, Kate A.; Unruh, Scott A.; Combs, H. Jason; Donnelly, Joseph E.; Sutton, Sarah; Abbey, Bryce M.

    2008-01-01

    This article describes the results of a study that helped determine common barriers to active commuting to and from school, as well as the results of a Walking School Bus program that was implemented at two neighborhood elementary schools in Nebraska. While parental perceived barriers to active commuting may influence the travel choices of…

  10. The One-Dimensional Random Walk

    NSDL National Science Digital Library

    McGath, Gary

    Created by authors Gary McGath and Paul Trunfio of Boston University's Center for Polymer Studies, this is the description and instructions for the One-Dimensional Random Walk applet. This Applet relates random coin-flipping to random motion. It strives to show that randomness (coin-flipping) leads to some sort of predictable outcome (the bell-shaped curve).

  11. Periodic Jitter Amplitude Calibration with Walking Strobe

    Microsoft Academic Search

    Lucy Liu; Eddie Lew

    2006-01-01

    Jitter insertion is a feature an automatic test equipment (ATE) provides for high speed SerDes device jitter tolerance testing. The amplitude of inserted periodic jitter (PJ) and its frequency are programmable. This article focuses on a technique developed to measure and calibrate the PJ amplitude of the ATE jitter insertion circuit. It uses a measurement tool called the walking strobe

  12. Kinesin: walking, crawling or sliding along?

    E-print Network

    Yildiz, Ahmet

    are the fastest kinesins (w2 mm secK1 ) that transport synaptic vesicles towards axons in neuKinesin: walking, crawling or sliding along? Ahmet Yildiz and Paul R. Selvin Department of Physics, University of Illinois, Urbana-Champaign, IL 61801, USA Kinesins are microtubule-based motor proteins

  13. Power grid analysis using random walks

    Microsoft Academic Search

    Haifeng Qian; Sani R. Nassif; Sachin S. Sapatnekar

    2005-01-01

    This paper presents a linear-time algorithm for the DC analysis of a power grid, based on a random walk technique. Experimental results show that the proposed method is faster than existing approaches and has an acceptable error margin. It also has a desirable property of localizing computation, and can be extended to RC- network transient analysis. This method has been

  14. The Cover Time of Deterministic Random Walks

    Microsoft Academic Search

    Tobias Friedrich; Thomas Sauerwald

    2010-01-01

    The rotor router model is a popular deterministic analogue of a random walk\\u000aon a graph. Instead of moving to a random neighbor, the neighbors are served in\\u000aa fixed order. We examine how fast this \\

  15. 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.…

  16. 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.

  17. 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.

  18. ROBUST VARIANCE REDUCTION FOR RANDOM WALK METHODS

    E-print Network

    Skeel, Robert

    ROBUST VARIANCE REDUCTION FOR RANDOM WALK METHODS GANG ZOU AND ROBERT D. SKEEL SIAM J. SCI. COMPUT of the reciprocal of the number of trials. Efficiency depends critically on variance reduction. A general strategy greatly enhances the effectiveness of biased Brownian dynamics. Key words. variance reduction, importance

  19. Autonomous exoskeleton reduces metabolic cost of walking.

    PubMed

    Mooney, Luke M; Rouse, Elliott J; Herr, Hugh M

    2014-01-01

    We developed an autonomous powered leg exoskeleton capable of providing large amounts of positive mechanical power to the wearer during powered plantarflexion phase of walking. The autonomous exoskeleton consisted of a winch actuator fasted to the shin which pulled on fiberglass struts attached to a boot. The fiberglass struts formed a rigid extension of the foot when the proximal end of the strut was pulled in forward by the winch actuator. This lightweight, geometric transmission allowed the electric winch actuator to efficiently produce biological levels of power at the ankle joint. The exoskeleton was powered and controlled by lithium polymer batteries and motor controller worn around the waist. Preliminary testing on two subjects walking at 1.4 m/s resulted in the exoskeleton reducing the metabolic cost of walking by 6-11% as compared to not wearing the device. The exoskeleton provided a peak mechanical power of over 180 W at each ankle (mean standard ± deviation) and an average positive mechanical power of 27 ± 1 W total to both ankles, while electrically using 75-89 W of electricity. The batteries (800 g) used in this experiment are estimated to be capable of providing this level of assistance for up to 7 km of walking. PMID:25570638

  20. Collisions Among Random Walks on a Graph

    Microsoft Academic Search

    Don Coppersmith; Prasad Tetali; Peter Winkler

    1993-01-01

    A token located at some vertex v of a connected, undirected graph G on n vertices issaid to be taking a "random walk" on G if, whenever it is instructed to move, it moveswith equal probability to any of the neighbors of v. We consider the following problem:suppose that two tokens are placed on G, and at each tick of

  1. Two Walking Robot Simulators Matthew P. Kelly

    E-print Network

    Ruina, Andy L.

    for the Cornell Ranger [2]. The simple biped model is based on three point masses, connected by force ac- tuators, with reliance on an- kle torques. Capture Point controlled robots (Mark Raibert's hopping robots [5Two Walking Robot Simulators Matthew P. Kelly Cornell University mpk72@cornell.edu July 29, 2014

  2. 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…

  3. Dynamic arm swinging in human walking

    PubMed Central

    Collins, Steven H.; Adamczyk, Peter G.; Kuo, Arthur D.

    2009-01-01

    Humans tend to swing their arms when they walk, a curious behaviour since the arms play no obvious role in bipedal gait. It might be costly to use muscles to swing the arms, and it is unclear whether potential benefits elsewhere in the body would justify such costs. To examine these costs and benefits, we developed a passive dynamic walking model with free-swinging arms. Even with no torques driving the arms or legs, the model produced walking gaits with arm swinging similar to humans. Passive gaits with arm phasing opposite to normal were also found, but these induced a much greater reaction moment from the ground, which could require muscular effort in humans. We therefore hypothesized that the reduction of this moment may explain the physiological benefit of arm swinging. Experimental measurements of humans (n = 10) showed that normal arm swinging required minimal shoulder torque, while volitionally holding the arms still required 12 per cent more metabolic energy. Among measures of gait mechanics, vertical ground reaction moment was most affected by arm swinging and increased by 63 per cent without it. Walking with opposite-to-normal arm phasing required minimal shoulder effort but magnified the ground reaction moment, causing metabolic rate to increase by 26 per cent. Passive dynamics appear to make arm swinging easy, while indirect benefits from reduced vertical moments make it worthwhile overall. PMID:19640879

  4. Parametric Excitation Mechanisms for Dynamic Bipedal Walking

    Microsoft Academic Search

    Fumihiko Asano; Sang-ho Hyon; Zhi Wei Luo

    2005-01-01

    It is already clarified throughout studies of passive dynamic walking mechanisms that the common nec essary condition for dynamic gait generation comes from the requirement on mechanical energy restoration. Until now we have treated only rotational joints of the robot, whereas in this paper we consider a novel dynamic gait generation method based on mechanical energy restoration by parametric excitation

  5. Iterative learning control for biped walking

    Microsoft Academic Search

    Qi-Zhi Zhang; Chee-Meng Chew; Ya-Li Zhou; Qiu-Ling Zhao; Pei Li

    2010-01-01

    In this paper, an iterative learning control (ILC) approach is proposed for biped walking control. The biped robot is powered by applying an impulsive push along the stance leg just before the heel strikes. The ILC law is designed based on Poincare? map, and applied to learn the desired impulsive push at every step in the presence of system uncertainties.

  6. Stable dynamic walking of a quadruped robot \\

    Microsoft Academic Search

    Christophe Maufroy; Tomohiro Nishikawa; Hiroshi Kimura

    2010-01-01

    In this study, we intend to show the basis of a general legged locomotion controller with the ability to integrate both posture and rhythmic motion controls and shift continuously from one control method to the other according to the walking speed. The rhythmic motion of each leg in the sagittal plane is generated by a single leg controller which controls

  7. Communities, Random Walks, and Social Sybil Defense

    E-print Network

    Alvisi, Lorenzo

    Communities, Random Walks, and Social Sybil Defense Lorenzo Alvisi , Allen Clement , Alessandro to distributed systems and online social networks. The goal of sybil defense is to accurately identify sybil identities. This paper surveys the evolution of sybil defense protocols that leverage the structural

  8. Biomechanics of walking, running, and sprinting

    Microsoft Academic Search

    Roger A. Mann; John Hagy

    1980-01-01

    A biomechanical study of 13 runners which consisted of 2 male sprinters, 5 experienced joggers, and 6 elite long-distance runners were studied. We obtained hip, knee, and ankle joints motions in the sagittal plane and electromyographic data from specific muscle groups.As the speed of gait increased, the length of stance phase progressively decreased from 62% for walking to 31% for

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

    E-print Network

    Norio Konno; Hideo Mitsuhashi; Iwao Sato

    2015-05-04

    Recently, the quaternionic quantum walk was formulated by the first author as a generalization of discrete-time quantum walks. We treat the right eigenvalue problem of quaternionic matrices to analysis the spectra of its transition matrix. The way to obtain all the right eigenvalues of a quaternionic matrix is given. From the unitary condition on the transition matrix of the quaternionic quantum walk, we deduce some properties about it. Our main results, Theorem 5.3, determine all the right eigenvalues of a quaternionic quantum walk by use of those of the corresponding weighted matrix. In addition, we give some examples of quaternionic quantum walks and their right eigenvalues.

  10. Complexity analysis of quantum walk based search algorithms

    E-print Network

    B. L. Douglas; J. B. Wang

    2014-08-07

    We present several families of graphs that allow both efficient quantum walk implementations and efficient quantum walk based search algorithms. For these graphs, we construct quantum circuits that explicitly implement the full quantum walk search algorithm, without reference to a `black box' oracle. These circuits provide a practically implementable method to explore quantum walk based search algorithms with the aim of eventual real-world applications. We also provide a numerical analysis of a quantum walk based search along a twisted toroid family of graphs, which requires O($\\sqrt{n}$ log($n$)) elementary 2-qubit quantum gate operations to find a marked node.

  11. Non-uniform mixing of quantum walk on cycles

    E-print Network

    William Adamczak; Kevin Andrew; Leon Bergen; Dillon Ethier; Peter Hernberg; Jennifer Lin; Christino Tamon

    2007-08-15

    A classical lazy random walk on cycles is known to mix to the uniform distribution. In contrast, we show that a continuous-time quantum walk on cycles exhibit strong non-uniform mixing properties. Our results include the following: - The instantaneous distribution of a quantum walk on most even-length cycles is never uniform. - The average distribution of a quantum walk on any Abelian circulant graph is never uniform. As a corollary, the average distribution of a quantum walk on any standard circulant graph, such as the cycles, complete graphs, and even hypercubes, is never uniform.

  12. Coverage-Adaptive Random Walks for Fast Sensory Data Collection

    NASA Astrophysics Data System (ADS)

    Angelopoulos, Constantinos-Marios; Nikoletseas, Sotiris; Patroumpa, Dimitra; Rolim, Jose

    Random walks in wireless sensor networks can serve as fully local, very simple strategies for sink motion that significantly reduce energy dissipation a lot but increase the latency of data collection. To achieve satisfactory energy-latency trade-offs the sink walks can be made adaptive, depending on network parameters such as density and/or history of past visits in each network region; but this increases the memory requirements. Towards better balances of memory/performance, we propose three new random walks: the Random Walk with Inertia, the Explore-and-Go Random Walk and the Curly Random Walk; we also introduce a new metric (Proximity Variation) that captures the different way each walk gets close to the network nodes over time. We implement the new walks and experimentally compare them to known ones. The simulation findings demonstrate that the new walks' performance (cover time) gets close to the one of the (much stronger) biased walk with memory, while in some other respects (partial cover time, proximity variation) they even outperform it. We note that the proposed walks have been fine-tuned in the light of experimental findings.

  13. Cardiovascular responses associated with daily walking in subacute stroke.

    PubMed

    Prajapati, Sanjay K; Mansfield, Avril; Gage, William H; Brooks, Dina; McIlroy, William E

    2013-01-01

    Despite the importance of regaining independent ambulation after stroke, the amount of daily walking completed during in-patient rehabilitation is low. The purpose of this study is to determine if (1) walking-related heart rate responses reached the minimum intensity necessary for therapeutic aerobic exercise (40%-60% heart rate reserve) or (2) heart rate responses during bouts of walking revealed excessive workload that may limit walking (>80% heart rate reserve). Eight individuals with subacute stroke attending in-patient rehabilitation were recruited. Participants wore heart rate monitors and accelerometers during a typical rehabilitation day. Walking-related changes in heart rate and walking bout duration were determined. Patients did not meet the minimum cumulative requirements of walking intensity (>40% heart rate reserve) and duration (>10?minutes continuously) necessary for cardiorespiratory benefit. Only one patient exceeded 80% heart rate reserve. The absence of significant increases in heart rate associated with walking reveals that patients chose to walk at speeds well below a level that has meaningful cardiorespiratory health benefits. Additionally, cardiorespiratory workload is unlikely to limit participation in walking. Measurement of heart rate and walking during in-patient rehabilitation may be a useful approach to encourage patients to increase the overall physical activity and to help facilitate recovery. PMID:23476892

  14. Generalized atmospheric sampling of self-avoiding walks

    NASA Astrophysics Data System (ADS)

    van Rensburg, E. J. Janse; Rechnitzer, A.

    2009-08-01

    In this paper, we introduce a new Monte Carlo method for sampling lattice self-avoiding walks. The method, which we call 'GAS' (generalized atmospheric sampling), samples walks along weighted sequences by implementing elementary moves generated by the positive, negative and neutral atmospheric statistics of the walks. A realized sequence is weighted such that the average weight of states of length n is proportional to the number of self-avoiding walks from the origin cn. In addition, the method also self-tunes to sample from uniform distributions over walks of lengths in an interval [0, nmax]. We show how to implement GAS using both generalized and endpoint atmospheres of walks and analyse our data to obtain estimates of the growth constant and entropic exponent of self-avoiding walks in the square and cubic lattices.

  15. Cool walking: a new Markov chain Monte Carlo sampling method.

    PubMed

    Brown, Scott; Head-Gordon, Teresa

    2003-01-15

    Effective relaxation processes for difficult systems like proteins or spin glasses require special simulation techniques that permit barrier crossing to ensure ergodic sampling. Numerous adaptations of the venerable Metropolis Monte Carlo (MMC) algorithm have been proposed to improve its sampling efficiency, including various hybrid Monte Carlo (HMC) schemes, and methods designed specifically for overcoming quasi-ergodicity problems such as Jump Walking (J-Walking), Smart Walking (S-Walking), Smart Darting, and Parallel Tempering. We present an alternative to these approaches that we call Cool Walking, or C-Walking. In C-Walking two Markov chains are propagated in tandem, one at a high (ergodic) temperature and the other at a low temperature. Nonlocal trial moves for the low temperature walker are generated by first sampling from the high-temperature distribution, then performing a statistical quenching process on the sampled configuration to generate a C-Walking jump move. C-Walking needs only one high-temperature walker, satisfies detailed balance, and offers the important practical advantage that the high and low-temperature walkers can be run in tandem with minimal degradation of sampling due to the presence of correlations. To make the C-Walking approach more suitable to real problems we decrease the required number of cooling steps by attempting to jump at intermediate temperatures during cooling. We further reduce the number of cooling steps by utilizing "windows" of states when jumping, which improves acceptance ratios and lowers the average number of cooling steps. We present C-Walking results with comparisons to J-Walking, S-Walking, Smart Darting, and Parallel Tempering on a one-dimensional rugged potential energy surface in which the exact normalized probability distribution is known. C-Walking shows superior sampling as judged by two ergodic measures. PMID:12483676

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

    PubMed

    Reynolds, Andy M; Leprêtre, 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 Lévy 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 Lévy 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 Lévy walk family. It follows from this that vast numbers of Lévy walkers could be hiding in plain sight. PMID:24196232

  17. Holographic integral equations and walking technicolor

    SciTech Connect

    Alvares, Raul; Evans, Nick; Gebauer, Astrid; Weatherill, George James [School of Physics and Astronomy, Southampton University, Southampton, SO17 1BJ (United Kingdom)

    2010-01-15

    We study chiral symmetry breaking in the holographic D3-D7 system in a simple model with an arbitrary running coupling. We derive equations for the D7 embedding and show there is a light pion. In particular we present simple integral equations, involving just the running coupling and the quark self-energy, for the quark condensate and the pion decay constant. We compare these to the Pagels-Stokar or constituent quark model equivalent. We discuss the implications for walking technicolor theories. We also perform a similar analysis in the four-dimensional field theory whose dual is the nonsupersymmetric D3-D5 system and propose that it represents a walking theory in which the quark condensate has dimension 2+{radical}(3)

  18. 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.

  19. Random walks on finite lattice tubes.

    PubMed

    Henry, B I; Batchelor, M T

    2003-07-01

    Exact results are obtained for random walks on finite lattice tubes with a single source and absorbing lattice sites at the ends. Explicit formulas are derived for the absorption probabilities at the ends and for the expectations that a random walk will visit a particular lattice site before being absorbed. Results are obtained for lattice tubes of arbitrary size and each of the regular lattice types: square, triangular, and honeycomb. The results include an adjustable parameter to model the effects of strain, such as surface curvature, on the surface diffusion. Results for the triangular lattice tubes and the honeycomb lattice tubes model diffusion of adatoms on single walled zig-zag carbon nanotubes with open ends. PMID:12935205

  20. Quantum walks in the density operator picture

    E-print Network

    Chaobin Liu

    2015-06-08

    A new approach to quantum walks is presented. Considering a quantum system undergoing some unitary discrete-time evolution in a directed graph G, we think of the vertices of G as sites that are occupied by the quantum system, whose internal state is described by density operators. To formulate the unitary evolution, we define reflections in the tensor product of an internal Hilbert space and a spatial Hilbert space. We then construct unitary channels that govern the evolution of the system in the graph. The discrete dynamics of the system (called quantum walks) is obtained by iterating the unitary channel on the density operator of the quantum system. It turns out that in this framework, the action of the unitary channel on a density operator is described by the usual matrix multiplication.

  1. Quantum Parrondo's games using quantum walks

    E-print Network

    Adrian P. Flitney

    2012-09-11

    We study a quantum walk in one-dimension using two different "coin" operators. By mixing two operators, both of which give a biased walk with negative expectation value for the walker position, it is possible to reverse the bias through interference effects. This effect is analogous to that in Parrondo's games, where alternating two losing (gambling) games can produce a winning game. The walker bias is produced by introducing a phase factor into the coin operator, with two different phase factors giving games $A$ and $B$. We give the range of phases for which the Parrondo effect can be obtained with $A$ and $B$ played alternately or in other (repeated) deterministic sequences. The effect is transitory. For sufficiently large times the original bias resumes.

  2. Quantum walks with non-Abelian anyons.

    PubMed

    Lehman, Lauri; Zatloukal, Vaclav; Brennen, Gavin K; Pachos, Jiannis K; Wang, Zhenghan

    2011-06-10

    We study the single particle dynamics of a mobile non-Abelian anyon hopping around many pinned anyons on a surface, by modeling it with a discrete time quantum walk. During the evolution, the spatial degree of freedom of the mobile anyon becomes entangled with the fusion degrees of freedom of the collective system. Each quantum trajectory makes a closed braid on the world lines of the particles establishing a direct connection between statistical dynamics and quantum link invariants. We find that asymptotically a mobile Ising model anyon becomes so entangled with its environment that its statistical dynamics reduces to a classical random walk with linear dispersion in contrast to particles with Abelian statistics which have quadratic dispersion. PMID:21770487

  3. 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.

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

    PubMed Central

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

    2012-01-01

    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

  5. Integrating walks into academics: Authentic learning experiences

    Microsoft Academic Search

    Lenore Peachin Wineberg

    2000-01-01

    The goals of this university\\/school partnership were to: (1) integrate walks into the curriculum in a kindergarten and a fourth\\u000a grade classroom to enrich student learning, (2) promote university\\/school partnerships in collaborating on curriculum development,\\u000a (3) provide a teacher educator, four student teachers, and two experienced teachers an opportunity to put theory into practice,\\u000a and (4) reflect on benefits to

  6. Dynamic bipedal walking assisted by learning

    Microsoft Academic Search

    Chee-meng Chew; Gill A. Pratt

    2002-01-01

    This paper presents a general control architecture for bipedal walking which is based on a divide-and-conquer approach. Based on the architecture, the sagittal-plane motion-control algorithm is formulated using a control approach known as Virtual Model Control. A reinforcment learning algorithm is used to learn the key parameter of the swing leg control task so that speed control can be achieved.

  7. Multiple-Instance Learning Via Random Walk

    Microsoft Academic Search

    Dong Wang; Jianmin Li; Bo Zhang

    2006-01-01

    This paper presents a decoupled two stage solution to the multiple-instance learning (MIL) problem. With a constructed affinity\\u000a matrix to reflect the instance relations, a modified Random Walk on a Graph process is applied to infer the positive instances\\u000a in each positive bag. This process has both a closed form solution and an efficient iterative one. Combined with the Support

  8. Neighborhood Design for Walking and Biking

    PubMed Central

    Brown, Barbara B.; Smith, Ken R.; Hanson, Heidi; Fan, Jessie X.; Kowaleski-Jones, Lori; Zick, Cathleen D.

    2013-01-01

    Background Neighborhood designs often relate to physical activity and to BMI. Purpose Does neighborhood walkability/bikeability relate to BMI and obesity risk and does moderate-to-vigorous physical activity (MVPA) account for some of the relationship? Methods Census 2000 provided walkability/bikeability measures—block group proportions of workers who walk or bike to work, housing age, and population density—and National Health and Nutrition Examination Study (NHANES 2003–2006) provided MVPA accelerometer measures. Regression analyses (2011–2012) adjusted for geographic clustering and multiple control variables. Results Greater density and older housing were associated with lower male BMI in bivariate analyses, but there were no density and housing age effects in multivariate models. For women, greater proportions of neighborhood workers who walk to work (M=0.02) and more MVPA was associated with lower BMI and lower obesity risk. For men, greater proportions of workers who bike to work (M=0.004) and more MVPA was associated with lower BMI and obesity risk. For both effects, MVPA partially mediated the relationships between walkability/bikeability and BMI. If such associations are causal, doubling walk and bike-to-work proportions (to 0.04 and 0.008) would have –0.3 and –0.33 effects on the average BMIs of adult women and men living in the neighborhood. This equates to 1.5 lbs for a 64” woman and 2.3 lbs for a 69” man. Conclusions Although walking/biking to work is rare in the U.S., greater proportions of such workers in neighborhoods relate to lower weight and higher MVPA. Bikeability merits greater attention as a modifiable activity-friendliness factor, particularly for men. PMID:23415119

  9. Land Use, Residential Density, and Walking

    Microsoft Academic Search

    Daniel A. Rodríguez; Kelly R. Evenson; Ana V. Diez Roux; Shannon J. Brines

    2009-01-01

    Background: The neighborhood environment may play a role in encouraging sedentary patterns, especially for middle-aged and older adults. Purpose: The aim of this study was to examine the associations between walking and neighborhood population density, retail availability, and land-use distribution using data from a cohort of adults aged 45 to 84 years. Methods: Data from a multi-ethnic sample of 5529

  10. Efficient routing in MANETs using ordered walks

    Microsoft Academic Search

    Stephen DabideenJ; J. J. Garcia-Luna-Aceves

    2011-01-01

    A new approach for routing protocols operating in MANETs is presented in which flooding is not required to establish paths\\u000a from sources to destinations on demand in MANETs of moderate size. The concept of ordered walk is introduced as a depth-first search (DFS) that does not rely on geographical or virtual coordinate information and is much\\u000a more efficient than mere

  11. The compass rose andrand om walk tests

    Microsoft Academic Search

    Yue Fang

    2002-01-01

    The recent discovery of the compass rose pattern (Crack and Ledoit J. Finance 51(2) (1996) 751) has sparkedconsid erable interest among researchers. This paper explores the signi1cance of the e2ect of the compass rose pattern on random walk tests and measures to what extent its in3uence may limit the performance of test statistics. We show that in general, the asymptotic

  12. 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.

  13. A random walk approach to quantum algorithms

    Microsoft Academic Search

    Vivien M. Kendon

    2006-01-01

    The development of quantum algorithms based on quantum versions of random\\u000awalks is placed in the context of the emerging field of quantum computing.\\u000aConstructing a suitable quantum version of a random walk is not trivial: pure\\u000aquantum dynamics is deterministic, so randomness only enters during the\\u000ameasurement phase, i.e., when converting the quantum information into classical\\u000ainformation. The outcome

  14. Fast Cloth Animation on Walking Avatars

    Microsoft Academic Search

    T. Ivanov Vassilev; B. Spanlang; Yiorgos Chrysanthou

    2001-01-01

    This paper describes a fast technique for animating clothing on walking humans. It exploits a mass-spring cloth model but applies a new velocity directional modification approach to overcome its super-elasticity. The algorithm for cloth-body collision detection and response is based on image-space interference tests, unlike the existing ones that use object-space checks. The modern workstations' graphics hardware is used not

  15. Gait recognition and walking exercise intensity estimation.

    PubMed

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

    2014-04-01

    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, ?? 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

  16. 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.

  17. From Lévy walks to superdiffusive shock acceleration

    SciTech Connect

    Zimbardo, Gaetano; Perri, Silvia, E-mail: gaetano.zimbardo@fis.unical.it, E-mail: silvia.perri@fis.unical.it [Dipartimento di Fisica, Università della Calabria, Ponte P. Bucci, Cubo 31C, I-87036 Arcavacata di Rende (Italy)

    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 Lévy 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 Lévy 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 Lévy 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.

  18. 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

  19. Modelling early infant walking: Testing a generic CPG architecture on the NAO humanoid

    Microsoft Academic Search

    Gauss Lee; Robert Lowe; Tom Ziemke

    2011-01-01

    In this article, a simple CPG network is shown to model early infant walking, in particular the onset of independent walking. The difference between early infant walking and early adult walking is addressed with respect to the underlying neurophysiology and evaluated according to gait attributes. Based on this, we successfully model the early infant walking gait on the NAO robot

  20. Influences of Physical Environment on Corridor Walking Among Assisted Living Residents: Findings From Focus Group Discussions

    Microsoft Academic Search

    Zhipeng Lu; Susan D. Rodiek; Mardelle M. Shepley; Michael Duffy

    2011-01-01

    Walking has multiple physical and psychological benefits for older people. This study explores corridor walking behaviors and perceptions of corridor walkability in assisted living residents. Focus groups were conducted with 50 residents in six assisted living facilities in Texas. The data were analyzed by the constant comparative method. The findings revealed three types of corridor walking: walking to destination, walking

  1. Immediate effects of a single inclined treadmill walking session on level ground walking in individuals after stroke.

    PubMed

    Phadke, Chetan P

    2012-04-01

    Propulsion and paretic plantar flexor activity after stroke are deficient in walking. This study examined whether walking on an inclined treadmill increased muscle activity and whether it resulted in increased propulsion and muscle activity during level ground walking. Nine people with hemiparesis caused by stroke and nine healthy controls participated. The participants walked at treadmill inclines of 0, 2.5, and 5 degrees for 5 mins at each level, for a total walking period of 15 mins. Surface electromyograms were obtained from the tibialis anterior and medial gastrocnemius muscles. Anterior-posterior ground reaction forces and electromyograms were recorded during overground walking before, immediately after, and 20 mins after inclined treadmill walking. Plantar flexor activity was significantly greater at 2.5 and 5 degree incline compared with no incline bilaterally in healthy controls and in the nonparetic side of people with stroke (P < 0.025) but not in the paretic side (P > 0.245). Electromyograms in control and stroke groups and the propulsive force in controls during overground walking were not significantly different before and after inclined treadmill walking. Overground propulsive forces after inclined treadmill walking in the stroke group were marginally higher in the nonparetic side (P < 0.025) but were slightly lower in the paretic side (P < 0.025). Future tests should study the effect of higher inclines and faster treadmill speeds on paretic electromyogram activity. PMID:22173086

  2. Effects of nordic walking compared to conventional walking and band-based resistance exercise on fitness in older adults.

    PubMed

    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 min·day(-1) (warm-up 10-15 min, main exercise 30-40, and cool down 10-15 min), 3 days·week(-1) (NW and CW) or 2 day·week(-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 PointsNordic 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

  3. 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 min·day?1 (warm-up 10-15 min, main exercise 30-40, and cool down 10-15 min), 3 days·week?1 (NW and CW) or 2 day·week?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

  4. 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

  5. Upper limits of Sinai’s walk in random scenery

    Microsoft Academic Search

    Olivier Zindy

    2008-01-01

    We consider Sinai’s walk in i.i.d. random scenery and focus our attention on a conjecture of Révész concerning the upper limits of Sinai’s walk in random scenery when the scenery is bounded from above. A close study of the competition between the concentration property for Sinai’s walk and negative values for the scenery enables us to prove that the conjecture is

  6. Upper limits of Sinai's walk in random scenery

    Microsoft Academic Search

    Olivier Zindy

    2006-01-01

    We consider Sinai's walk in i.i.d. random scenery and focus our attention on a conjecture of R\\\\'ev\\\\'esz \\\\cite{r05} concerning the upper limits of Sinai's walk in random scenery when the scenery is bounded from above. A close study of the competition between the concentration property for Sinai's walk and negative values for the scenery enables us to prove that the

  7. Walk-Throughs in Web Usability: Cognitive, Activity, and

    Microsoft Academic Search

    Chapter XI

    The evaluators of a Web site have a need for robust and easy-to-use usability inspection methods to help them to systematically identify the possible usability problems of the Web site being analysed. Three usability inspection methods — heuristic walk-through (HW), cognitive walk-through (CW), and activity walk-through (AW) — are reviewed in this chap- ter. This chapter discusses the relative advantages

  8. Random walk in quasi-periodic random environment

    E-print Network

    Paris-Sud XI, Université de

    of finite range random walk on Z in random environment. The set of possible jumps is assumed to be a fixed Abstract We consider a one-dimensional random walk with finite range in a random medium de- scribed classifications : 60F17, 60J10, 60K37, 37A45, 37C55, 37E10. Key words and phrases : finite range random walk

  9. Mean cover time of one-dimensional persistent random walks.

    PubMed

    Chupeau, Marie; Bénichou, Olivier; Voituriez, Raphaël

    2014-06-01

    The cover time is defined as the time needed for a random walker to visit every site of a confined domain. Here, we focus on persistent random walks, which provide a minimal model of random walks with short-range memory. We derive the exact expression of the mean cover time of a one-dimensional lattice by such a persistent random walk, both for periodic and reflecting boundary conditions. PMID:25019746

  10. Reactive navigation of an intelligent robotic walking aid

    Microsoft Academic Search

    Birgit Graf

    2001-01-01

    This work presents the intelligent walking aid system Care-O-bot. Care-O-bot is the prototype of a multifunctional home care system, to be used by elderly people in order to live independently in their homes. In order to enable easy manipulation of the robot platform, the way to use it as a walking aid has been adapted to conventional walking aid systems.

  11. Discrete-time Quantum Walks in random artificial Gauge Fields

    E-print Network

    G. Di Molfetta; F. Debbasch

    2015-05-30

    Discrete-time quantum walks (DTQWs) in random artificial electric and gravitational fields are studied analytically and numerically. The analytical computations are carried by a new method which allows a direct exact analytical determination of the equations of motion obeyed by the average density operator. It is proven that randomness induces decoherence and that the quantum walks behave asymptotically like classical random walks. Asymptotic diffusion coefficients are computed exactly. The continuous limit is also obtained and discussed.

  12. 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

  13. Mechanical and physiological effects of varying pole weights during Nordic walking compared to walking

    Microsoft Academic Search

    Thorsten Schiffer; Axel Knicker; Melissa Montanarella; Heiko K. Strüder

    2011-01-01

    The study investigated the effect of varying pole weights on energy expenditure, upper limb muscle activation and on forces\\u000a transmitted to the poles during Nordic walking (NW). Twelve women [age = 21 (2) years, body mass = 60.8 (6) kg, height = 1.71\\u000a (0.06) m] participated in five 7-min walking tests randomly chosen without poles (W), with normal NW poles (NW) or with added\\u000a masses of 0.5 kg (NW + 0.5) 1.0 kg

  14. 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.

  15. Qubit state transfer via discrete-time quantum walks

    NASA Astrophysics Data System (ADS)

    Yalç?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.

  16. 18.366 Random Walks and Diffusion, Spring 2005

    E-print Network

    Bazant, Martin Z.

    Discrete and continuum modeling of diffusion processes in physics, chemistry, and economics. Topics include central limit theorems, continuous-time random walks, Levy flights, correlations, extreme events, mixing, ...

  17. 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…

  18. Is Random Walk Truly Memoryless -Traffic Analysis and Source Location Privacy under Random Walks

    E-print Network

    Gao, Jie

    with limited computation and storage capacities, the fact that sensor nodes use wireless medium makes depends only on the current node and not on the sequence of events that preceded it. With these properties of the memoryless property of a random walk applied for protecting source location privacy in a wireless sensor

  19. 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…

  20. Walking on a Tightrope: Parents Shouldn't Have to Walk It Alone.

    ERIC Educational Resources Information Center

    Griffel, Gail

    1991-01-01

    Maintains that parents of a handicapped child, for example, a child with cerebral palsy, are "walking a tightrope." Successful intervention with the disabled child in the classroom is possible only when there is strong teacher-parent communication. This position is illustrated by an account of a parent's personal experience. (BB)

  1. Walking the Walk: The Association Between Community Environmentalism and Green Travel Behavior

    Microsoft Academic Search

    Matthew E. Kahn; Eric A. Morris

    2009-01-01

    Problem: Reducing gasoline consumption could sharply curtail greenhouse gas emissions. Ongoing research seeks to document factors associated with green travel behavior, like walking and transit use.Purpose: We seek to determine whether green beliefs and values are associated with green travel behavior. We measure whether residents of communities with environmentalist attributes drive less, consume less gasoline, and are more likely to

  2. Agnostically Learning Juntas from Random Walks

    E-print Network

    Arpe, Jan

    2008-01-01

    We prove that the class of functions g:{-1,+1}^n -> {-1,+1} that only depend on an unknown subset of k 0 and access to a random walk on {-1,+1}^n labeled by an arbitrary function f:{-1,+1}^n -> {-1,+1}, finds with probability at least 1-delta a k-junta that is (opt(f)+epsilon)-close to f, where opt(f) denotes the distance of a closest k-junta to f.

  3. 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

  4. Let Your Ears Do the Walking

    NSDL National Science Digital Library

    Engineering K-PhD Program,

    Students experience a simulation of echolation, using the sensory method to walk along a path while blindfolded. This relates to the issue of bycatching by fisheries, which they learned about In the associated lesson. Bycatching affects marine animals, especially dolphins, which use echolocation to identify the location of objects in the water, but have difficulty identifying nets, and thus are often caught accidentally. Students learn how echolocation works, why certain animals use it to determine the size, shape and distance of objects, and how humans can potentially take advantage of dolphins' echolocation ability when developing bycatch avoidance methods.

  5. Novel Image Encryption based on Quantum Walks

    NASA Astrophysics Data System (ADS)

    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.

  6. Cavity QED-based quantum walk 

    E-print Network

    Di, TG; Hillery, M.; Zubairy, M. Suhail

    2004-01-01

    ?t? with ?left? or ?right? chirality. A simulation of such a quantum walk is presented in Fig. 1. We plot the probabilities PL,n and PR,n which are the probabilities with the left and right chiralities, respec- tively, for the particle... step, we need two interactions with the classical fields supplemented FIG. 1. The probabilities PL,n and PR,n are plotted vs n. At the initial time, the particle is located at the position n0=0 and the direction of movement is left. Total number...

  7. Continuous time random walks on moving fluids

    NASA Astrophysics Data System (ADS)

    Compte, Albert

    1997-06-01

    The scheme of the continuous time random walk (CTRW) is generalized to include the possibility of a moving background. It is shown that this generalization reproduces in the macroscopic limit the usual diffusion-advection equation and the properties of standard diffusion in a shear flow. The new formalism is then used to derive the corresponding macroscopic equation for CTRW's with infinite mean squared step length and with infinite mean waiting time in a moving fluid. For these two CTRW's we finally include an analysis of the dispersion in three different two-dimensional linear shear flows.

  8. Pier Walk '97: The Electronic Version

    NSDL National Science Digital Library

    Pier Walk, hosted by the Navy Pier in Chicago, is the world's largest outdoor sculpture exhibition, showcasing the talents of 110 artists from 7 countries. This site offers a virtual tour in two formats: a text based index, essentially a slide show in five parts, and a pictorial index with thumbnails and some basic information about each artist. There is also a pop-up shortcut Java menu without text. Another feature is a modest collection of links to other sculpture sites, a nice resource as paintings seem to dominate the current world of virtual exhibitions.

  9. Behavioral and neural correlates of imagined walking and walking-while-talking in the elderly.

    PubMed

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

    2014-08-01

    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

  10. The Fibonacci quantum walk and its cassical trace map

    E-print Network

    Alejandro Romanelli

    2008-02-15

    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.

  11. Independent Walking After Neonatal Arterial Ischemic Stroke and Sinovenous Thrombosis

    Microsoft Academic Search

    Meredith R. Golomb; Gabrielle A. deVeber; Daune L. MacGregor; Trish Domi; Hilary Whyte; Derek Stephens; Paul T. Dick

    2003-01-01

    Few studies have examined walking after neonatal arterial ischemic stroke and sinovenous thrombosis. We looked at the development of walking in a retrospective and consecutive cohort study of 88 term and near-term neonates. We used Kaplan-Meier survival curves and Cox proportional hazards models to assess (1) sex, (2) stroke type (arterial ischemic stroke or sinovenous thrombosis), (3) number of cerebral

  12. Humanoid Robot Walking Control on Inclined Planes Utku Seven1

    E-print Network

    Yanikoglu, Berrin

    Humanoid Robot Walking Control on Inclined Planes Utku Seven1 , Tunc Akbas2 , Kaan Can Fidan3 of a humanoid robot. This paper presents a study on bipedal walk on inclined planes. A Zero Moment Point (ZMP in the full-dynamics 3-D simulations. Simulations are carried out on even floor and inclined planes

  13. Protein-DNA Interaction, Random Walks and Polymer Statistics

    E-print Network

    Mirny, Leonid

    Protein-DNA Interaction, Random Walks and Polymer Statistics by Michael Slutsky Submitted by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thomas J. Greytak Professor of Physics Associate Department Head for Education #12;Protein-DNA Interaction, Random Walks and Polymer Statistics by Michael Slutsky Submitted to the Physics Department on May

  14. Walking and running on yielding and fluidizing Feifei Qian1

    E-print Network

    Fearing, Ron

    Walking and running on yielding and fluidizing ground Feifei Qian1 , Tingnan Zhang1 , Chen Li1. At low frequencies, the robot used a quasi-static "rotary walking" mode, in which the granular material]. Forced granular media remain solid below the yield stress but flow like a fluid when the yield stress

  15. Characterization of the brachial artery shear stress following walking exercise

    Microsoft Academic Search

    Jaume Padilla; Ryan A Harris; Lawrence D Rink; Janet P Wallace

    Habitual exercise provides repeated episodes of elevated vascular shear stress (SS), which may be a mechanism for repair of endothelial dysfunction in dis- ease. Our aim was to determine the brachial artery SS during the 3-hour period fol- lowing single bouts of low, moderate, and high-intensity walking exercise. In a ran- domized crossover design, 14 men walked for 45 minutes

  16. A dynamically-Balanced Walking Biped Graham Mann

    E-print Network

    New South Wales, University of

    A dynamically-Balanced Walking Biped Graham Mann , Bruce Armstrong , Phil Preston , Barry Drake, dynamically-balanced two-legged walking. The machine is physically complete and demonstrates reasonable reliability in movement control including dynamically-balanced standing. High-level reinforcement learning

  17. Automatic vs hand-controlled walking of paraplegics

    Microsoft Academic Search

    Dejan Popovi?; Milovan Radulovi?; Laszlo Schwirtlich; Novak Jaukovi?

    2003-01-01

    A rule-based control and its application in functional electrical stimulation (FES) assisted walking of subjects with paraplegia are described in this paper. The design of rules for control comprises the following two steps: (1) determination of muscle activation patterns by using a fully customized spatial (3D) model of paraplegic walking, and (2) learning of rules, that is, correlation between the

  18. Learning to Walk by Imitation in Low-Dimensional Subspaces

    Microsoft Academic Search

    Rawichote Chalodhorn; David B. Grimes; Keith Grochow; Rajesh P. N. Rao

    2010-01-01

    In this paper, we provide the first demonstration that a humanoid robot can learn to walk directly by imitating a human gait obtained from motion capture (mocap) data without any prior information of its dynamics model. Programming a humanoid robot to perform an action (such as walking) that takes into account the robot's complex dynamics is a challenging problem. Traditional

  19. Change in action: how infants learn to walk down slopes

    Microsoft Academic Search

    Simone V. Gill; Karen E. Adolph; Beatrix Vereijken

    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

  20. Almost sure estimates for the concentration neighborhood of Sinai's walk

    Microsoft Academic Search

    Pierre Andreoletti; F. Joliot-Curie

    2005-01-01

    We consider Sinai's random walk in random environment. We prove that infinitely often (i.o.) the size of the concentration neighborhood of this random walk is almost surely bounded. As an application we get that i.o. the maximal distance between two favorite sites is almost surely bounded.

  1. Effect of backward walking on attention: possible application on ADHD.

    PubMed

    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

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

    PubMed

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

    2009-02-01

    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

  3. WINDINGS OF PLANAR RANDOM WALKS AND AVERAGED DEHN FUNCTION

    E-print Network

    Paris-Sud XI, Université de

    WINDINGS OF PLANAR RANDOM WALKS AND AVERAGED DEHN FUNCTION BRUNO SCHAPIRA AND ROBERT YOUNG Abstract. We prove sharp estimates on the expected number of windings of a simple random walk on the square area needed to fill a random curve with a disc. 1. Introduction The winding numbers of random curves

  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. On recurrence and transience of self-interacting random walks

    E-print Network

    Sousi, Perla

    the walk takes also depends on the past. Recently there has been a lot of interest in random walks of Cambridge, Cambridge, UK; p.sousi@statslab.cam.ac.uk #12;Definition 1.1. Let µ1, . . . , µk be k probability

  6. Changes in postural sway as a function of prolonged walking.

    PubMed

    Thomas, Kathleen S; VanLunen, Bonnie L; Morrison, Steven

    2013-02-01

    For optimal balance, the postural system needs to quickly detect and respond to perturbations. The aim of this study was to investigate the immediate and long-term impact of walking at different speeds on standing balance and postural stability. Center of pressure (COP) motion was measured from 14 young individuals at discrete time intervals after they walked on a treadmill at three speeds (preferred walking speed (PWS), 120 %-PWS, 140 %-PWS). Results revealed that walking at a faster speed had the greatest impact on postural stability. This was reflected by increases in the amount (path length, range, 95 % ellipse), variability (standard deviation, SD), and structure (approximate entropy, ApEn) of COP motion and were most evident when compared to pre-walking assessments. In subsequent trials following pre-walking assessments there was a leveling-off for specific COP variables (range, variability, and ApEn) and a decline in path length. This plateau effect was observed even though measures of physical exertion (HR, RPE) continued to increase over the entire walking trial. Together, these results indicate that, despite the constant task demands induced by fast walking, the postural system was able to rapidly compensate and adjust appropriately. PMID:22806086

  7. Emulating Human Leg Impairments and Disabilities on Humanoid Robots Walking

    E-print Network

    Paris-Sud XI, Université de

    Emulating Human Leg Impairments and Disabilities on Humanoid Robots Walking S´ebastien Lengagne for emulating human walking motions with leg impairments or disabilities using humanoid robots. Our optimal by the application of humanoid robots to human study and diagnosis. If we are able to pa- rameterize the disabled

  8. Random Walks On Finite Convex Sets Of Lattice Points

    Microsoft Academic Search

    Balint Virag

    1998-01-01

    This paper examines the convergence of nearest-neighbor random walks on convex subsets of the latticesZd. The main result shows that for fixedd, O(?2) steps are sufficient for a walk to “get random,” where ? is the diameter of the set. Toward this end a new definition of convexity is introduced for subsets of lattices, which has many important properties of

  9. ON MIXING OF CERTAIN RANDOM WALKS, CUTOFF PHENOMENON AND SHARP

    E-print Network

    Pak, Igor

    are certain random walks on vector spaces over finite fields. We show that the behavior of such walks is given G be a finite group, and let S be a set of generators of G. Consider a Markov chain X t on G which as follows. Start with an empty set and add random matroid elements one by one until we get a base

  10. ON MIXING OF CERTAIN RANDOM WALKS, CUTOFF PHENOMENON AND SHARP

    E-print Network

    Pak, Igor

    walks. Here is a general setup of the problem. Let G be a finite group, and let S b* *e a set of a geometric random walk. Let V = Fnq be an abelian group of vectors in a finite vector space. A subset corresponding to S. Define a random matroid process as follows. Start with an empty set and add random matroid

  11. Kinematic strategies for walking across a destabilizing rock surface

    Microsoft Academic Search

    Deanna H. Gates; Jason M. Wilken; Shawn J. Scott; Emily H. Sinitski; Jonathan B. Dingwell

    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 15 healthy, young subjects walked on level ground (LG) and a destabilizing loose rock surface (RS) at four controlled speeds. There

  12. Modular control of human walking: Adaptations to altered mechanical demands

    E-print Network

    altered. Walking simulations were generated that emulated human subjects who had their body weight andModular control of human walking: Adaptations to altered mechanical demands Craig P. McGowan a support Load carrying Muscles synergies Biomechanical function a b s t r a c t Studies have suggested

  13. Dynamic analysis of human walking Francois Faure, Gilles Debunne,

    E-print Network

    Boyer, Edmond

    -based simulation of the motion BC89]. The body of the human gure is pro- vided with actuators at hinges, which, RGBC96, LvdPF96], exploiting biomechan- ical knowledge on human walking seems a better approach HWBO95 knowledge on human walking described by biomechanics into parametrized automatons delivering angular

  14. Walking in simulated reduced gravity: mechanical energy fluctuations and exchange

    E-print Network

    Kram, Rodger

    of walking in simulated reduced gravity. biomechanics; locomotion; human; mechanical work; energet- ics.--Walking humans conserve mechanical and, presum- ably, metabolic energy with an inverted pendulum-like ex) of the body's center of mass. This mechanism conserves mechanical energy and presumably metabolic energy

  15. The Simple Random Walk Snake on Z^4 is Recurrent

    E-print Network

    Benjamini, Itai

    2011-01-01

    Consider the branching simple random walk on Z^d indexed by a critical geometric Galton-Watson tree conditioned to survive. Using the concept of unimodular random graphs, we show that the walk is recurrent if and only if d is less than or equal to 4.

  16. The metabolic transition speed between backward walking and running

    Microsoft Academic Search

    Elmarie Terblanche; Werner A. Cloete; Pieter A. L. du Plessis; Jacques N. Sadie; Annemie Strauss; Marianne Unger

    2003-01-01

    Although the metabolic transition speed for forward exercise has already been determined, the walk–run transition speed for backward exercise has not been investigated before. The aim of this study was to determine the speed at which it becomes metabolically more efficient to run backwards than to walk backwards. Eighteen healthy volunteers, who successfully completed three backward exercise practice sessions, participated

  17. Tai Chi versus brisk walking in elderly women

    Microsoft Academic Search

    JOSEPH F. AUDETTE; YOUNG SOO JIN; RENEE NEWCOMER; LAUREN STEIN; GILLIAN DUNCAN; WALTER R. FRONTERA

    Purpose: to compare the effects of a short style of Tai Chi versus brisk walking training programme on aerobic capacity, heart rate variability (HRV), strength, flexibility, balance, psychological status and quality of life in elderly women. Methods: nineteen community-dwelling, sedentary women (aged 71.4 ± 4.5 years) were randomly assigned to Tai Chi Chuan (TCC; n = 11) or brisk walking

  18. An exploration of walking behaviour—An interpretative phenomenological approach

    Microsoft Academic Search

    Catherine D. Darker; Michael Larkin; David P. French

    2007-01-01

    The aim of this study was to provide a rich and detailed account of participants’ experiences of walking using the qualitative method of interpretative phenomenological analysis. Participants were a snowball sample of 10 members of the UK general public, aged 25–35 years, with equal numbers of males and females. Participants reported walking as not being “proper” exercise, and that it

  19. Walk and Talk: An Intervention for Behaviorally Challenged Youths

    ERIC Educational Resources Information Center

    Doucette, Patricia A.

    2004-01-01

    This qualitative research explored the question: Do preadolescent and adolescent youths with behavioral challenges benefit from a multimodal intervention of walking outdoors while engaging in counseling? The objective of the Walk and Talk intervention is to help the youth feel better, explore alternative behavioral choices, and learn new coping…

  20. Local environments as determinants of walking in Melbourne, Australia

    Microsoft Academic Search

    Rebecca Bentley; Damien Jolley; Anne Marie Kavanagh

    2010-01-01

    Structural changes to neighbourhoods that promote walking are likely to benefit everyone in a community and result in long-term improvements in the population's physical activity and health. We consider time spent walking in relation to objectively measured features of people's local environments (functionality, safety, destinations and aesthetics) in Melbourne, Australia. We used multilevel ordered logistic regression analysis to examine variations

  1. Functional electrical stimulation of walking: Function, exercise and rehabilitation

    Microsoft Academic Search

    T. A. Thrasher; M. R. Popovic

    2008-01-01

    For nearly half a century, functional electrical stimulation (FES) has been used to restore walking for people with paralysis and muscle weakness due to stroke and spinal cord injury. The first applications of the technology were intended to permanently replace lost neuromuscular function. Later, FES-assisted walking was found to have therapeutic benefits that include increased muscle strength, cardiovascular fitness and

  2. Walk Across Texas! http://walkacrosstexas.tamu.edu

    E-print Network

    a great stress reducer! It was great to be part of a team, and I have loved coaching others, too. IWalk Across Texas! http://walkacrosstexas.tamu.edu Walk Across Texas! is an eight-week program to help people of all ages support one another to establish the habit of regular physical activity. Walk

  3. 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…

  4. Walk-in Intake Form First Year Advising & Exploration

    E-print Network

    Wu, Shin-Tson

    Walk-in Intake Form First Year Advising & Exploration Student Development and Enrollment Services (Rev. 12/04/2012) Name: Current Major(s): PID: Current Minor(s): First Year Advising and Exploration to the First Year Advising & Exploration front desk to sign-in for the first available advisor during Walk

  5. Distracted walking: Cell phones increase injury risk for college pedestrians

    Microsoft Academic Search

    Despina Stavrinos; Katherine W. Byington; David C. Schwebel

    2011-01-01

    IntroductionDistraction on cell phones jeopardizes motor-vehicle driver safety, but few studies examine distracted walking. At particular risk are college students, who walk frequently in and near traffic, have increased pedestrian injury rates compared to other age groups, and frequently use cell phones. Method: Using an interactive and immersive virtual environment, two experiments studied the effect of cell phone conversation on

  6. Promoting Discussion in the Science Classroom Using Gallery Walks

    NSDL National Science Digital Library

    Mark Francek

    2006-09-01

    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.

  7. Walking on water: why your feet get wet

    NASA Astrophysics Data System (ADS)

    Shelley, Michael; Fontana, Jake; Palffy-Muhoray, Peter

    2009-03-01

    Walking on wet pavement during or after heavy rain results in wet shoes, and often, wet feet. We describe a peculiar transport process associated with walking on wet surfaces which results in the vamps, and frequently, the insides, of shoes getting wet. We discuss details of this process and compare experimental results with simple model predictions. Strategies for keeping feet dry will be considered.

  8. 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

  9. A new perspective on random walk modeling of particle dispersion

    Microsoft Academic Search

    L. Tao; K. R. Rajagopal; A. R. McFarland

    2002-01-01

    This note presents a random walk formulation of small particle tracking within the framework of averaged turbulence modeling. Several issues, such as a justification for the finite number of multi-point correlations to be taken, the adoption of just one two-point correlation rather than several, and construction of specific models, are discussed. It offers a new perspective on random walk modeling

  10. Alterations in muscle activation patterns during robotic-assisted walking

    Microsoft Academic Search

    Joseph M. Hidler; Anji E. Wall

    2005-01-01

    Objective. The goal of this study was to compare the muscle activation patterns in various major leg muscles during treadmill ambulation with those exhibited during robotic-assisted walking. Background. Robotic devices are now being integrated into neurorehabilitation programs with promising results. The influence of these devices on altering naturally occurring muscle activation patterns utilized during walking have not been quantified. Methods.

  11. 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…

  12. Computer Animation of Human Walking: a Survey Franck Multon1

    E-print Network

    Paris-Sud XI, Université de

    Computer Animation of Human Walking: a Survey Franck Multon1 , Laure France2 , Marie-Paule Cani Animation of human walking is a crucial problem in Computer Graphics: Many synthetic scenes involve virtual fteen years ago in Computer Graphics, with the rst work on \\knowledge- based" animation of human gures

  13. 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

  14. Elastic coupling of limb joints enables faster bipedal walking

    PubMed Central

    Dean, J.C.; Kuo, A.D.

    2008-01-01

    The passive dynamics of bipedal limbs alone are sufficient to produce a walking motion, without need for control. Humans augment these dynamics with muscles, actively coordinated to produce stable and economical walking. Present robots using passive dynamics walk much slower, perhaps because they lack elastic muscles that couple the joints. Elastic properties are well known to enhance running gaits, but their effect on walking has yet to be explored. Here we use a computational model of dynamic walking to show that elastic joint coupling can help to coordinate faster walking. In walking powered by trailing leg push-off, the model's speed is normally limited by a swing leg that moves too slowly to avoid stumbling. A uni-articular spring about the knee allows faster but uneconomical walking. A combination of uni-articular hip and knee springs can speed the legs for improved speed and economy, but not without the swing foot scuffing the ground. Bi-articular springs coupling the hips and knees can yield high economy and good ground clearance similar to humans. An important parameter is the knee-to-hip moment arm that greatly affects the existence and stability of gaits, and when selected appropriately can allow for a wide range of speeds. Elastic joint coupling may contribute to the economy and stability of human gait. PMID:18957360

  15. Energetics of Actively Powered Locomotion Using the Simplest Walking Model

    Microsoft Academic Search

    Arthur D. Kuo

    2002-01-01

    Human walking is a mechanically complex task that is powered by the activity of numerous muscles. This complexity makes it difficult to discern what principles govern the cost of transport. Simple models of walking have shown, however, that there are general principles that hold, such as the fact that the motion of the swing leg can be largely passive in

  16. Cool Walking: A New Markov Chain Monte Carlo Sampling Method

    E-print Network

    Head-Gordon, Teresa L.

    ) temperature and the other at a low temperature. Nonlocal trial moves for the low temperature walker are generated by first sampling from the high-temperature distribution, then performing a statistical quenching process on the sampled configuration to generate a C-Walking jump move. C-Walking needs only one high-temperature

  17. Towards active actuated natural walking humanoid robot legs

    Microsoft Academic Search

    Ren C. Luo; Chwan Hsen Chen; Yi Hao Pu; Jia Rong Chang

    2011-01-01

    The objective of this paper is to investigate towards active actuated natural walking humanoid robot legs. Conventional humanoid robots suffer from problems like artificial and unnatural motion, or low agility. To improve the performance of the humanoid robot, this paper introduces the idea which employs the active-actuated biped robot legs and the passive dynamic walkers with more naturally walking. The

  18. Mixing times for random walks on finite lamplighter groups

    Microsoft Academic Search

    Yuval Peres; David Revelle

    2004-01-01

    Given a finite graph G, a vertex of the lamplighter graph consists of a zero-one labeling of the vertices of G, and a marked vertex of G. For transitive graphs G, we show that, up to constants, the relaxation time for simple random walk in corresponding lamplighter graph is the maximal hitting time for simple random walk in G, while

  19. When the beautiful game becomes a walk in the park.

    PubMed

    2015-03-01

    VOLUNTEERS ARE being sought to participate in a study that aims to assess the effect of 'walking football' on their health. The sport was created to help keep those over 50 involved with football if they are not able to play the traditional game. Matches are played at a slower pace to avoid injuries, with players walking through games. PMID:25727616

  20. Compliant leg behaviour explains basic dynamics of walking and running

    Microsoft Academic Search

    Hartmut Geyer; Andre Seyfarth; Reinhard Blickhan

    2006-01-01

    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

  1. Random walks that avoid their past convex hull

    Microsoft Academic Search

    Omer Angel; Itai Benjamini; Balint Virag

    2002-01-01

    We introduce planar random walk conditioned to avoid its past convex hull, and we show that it escapes at a positive limsup speed. Experimental results show that fluctuations from a limiting direction are on the order of n^(3\\/4). This behavior is also observed for the extremal investor, a natural financial model related to the planar walk.

  2. One-dimensional quantum walk with unitary noise

    SciTech Connect

    Shapira, Daniel; Biham, Ofer; Bracken, A.J.; Hackett, Michelle [Racah Institute of Physics, Hebrew University, Jerusalem, 91904 (Israel); Department of Mathematics, University of Queensland, Brisbane, Queensland 4072 (Australia)

    2003-12-01

    The effect of unitary noise on the discrete one-dimensional quantum walk is studied using computer simulations. For the noiseless quantum walk, starting at the origin (n=0) at time t=0, the position distribution P{sub t}(n) at time t is very different from the Gaussian distribution obtained for the classical random walk. Furthermore, its standard deviation, {sigma}(t) scales as {sigma}(t){approx}t, unlike the classical random walk for which {sigma}(t){approx}{radical}(t). It is shown that when the quantum walk is exposed to unitary noise, it exhibits a crossover from quantum behavior for short times to classical-like behavior for long times. The crossover time is found to be T{approx}{alpha}{sup -2}, where {alpha} is the standard deviation of the noise.

  3. Random walk in dynamically disordered chains: Poisson white noise disorder

    SciTech Connect

    Hernandez-Garcia, E.; Pesquera, L.; Rodriguez, M.A.; San Miguel, M. (Universitat de les Illes Balears, Palma de Mallorca (Spain))

    1989-06-01

    Exact solutions are given for a variety of models of random walks in a chain with time-dependent disorder. Dynamic disorder is modeled by white Poisson noise. Models with site-independent (global) and site-dependent (local) disorder are considered. Results are described in terms of an affective random walk in a nondisordered medium. In the cases of global disorder the effective random walk contains multistep transitions, so that the continuous limit is not a diffusion process. In the cases of local disorder the effective process is equivalent to usual random walk in the absence of disorder but with slower diffusion. Difficulties associated with the continuous-limit representation of random walk in a disordered chain are discussed. In particular, the authors consider explicit cases in which taking the continuous limit and averaging over disorder sources do not commute.

  4. Stilt walking: how do we learn those first steps?

    PubMed

    Akram, Sakineh B; Frank, James S

    2009-09-01

    This study examined how young healthy adults learn stilt walking. Ten healthy male university students attended two sessions of testing held on two consecutive days. In each session participants performed three blocks of 10 stilt-walking trials. Angular movements of head and trunk and the spatial and temporal gait parameters were recorded. When walking on stilts young adults improved their gait velocity through modifications of step parameters while maintaining trunk movements close to that observed during normal over-ground walking. Participants improved their performance by increasing their step frequency and step length and reducing the double support percentage of the gait cycle. Stilts are often used for drywall installation, painting over-the-head areas and raising workers above the ground without the burden of erecting scaffolding. This research examines the locomotor adaptation as young healthy adults learn the complex motor task of stilt walking; a task that is frequently used in the construction industry. PMID:19606365

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

    PubMed

    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. PMID:25974527

  6. Ballistic Phase of Self-Interacting Random Walks

    E-print Network

    Dmitry Ioffe; Yvan Velenik

    2008-04-03

    We explain a unified approach to a study of ballistic phase for a large family of self-interacting random walks with a drift and self-interacting polymers with an external stretching force. The approach is based on a recent version of the Ornstein-Zernike theory developed in earlier works. It leads to local limit results for various observables (e.g. displacement of the end-point or number of hits of a fixed finite pattern) on paths of n-step walks (polymers) on all possible deviation scales from CLT to LD. The class of models, which display ballistic phase in the "universality class" discussed in the paper, includes self-avoiding walks, Domb-Joyce model, random walks in an annealed random potential, reinforced polymers and weakly reinforced random walks.

  7. 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.

  8. Models of Walking Technicolor on the Lattice

    E-print Network

    D. K. Sinclair; J. B. Kogut

    2014-10-30

    We study QCD with 2 colour-sextet quarks as a walking-Technicolor candidate. As such it provides a description of the Higgs sector of the standard model, in which the Higgs field is replaced by the Goldstone `pions' of this QCD-like theory, and the Higgs itself is the $\\sigma$. Such a theory will need to be extended if it is to also give masses to the quarks and leptons. What we are attempting to determine is whether it is indeed QCD-like and hence walking, or if it has an infrared fixed point making it a conformal field theory. We do this by simulating its lattice version at finite temperature and observing the running of the bare (lattice) coupling at the chiral transition, as the lattice spacing is varied, and comparing this running with that predicted by 2-loop perturbation theory. Our results on lattices with temporal extents ($N_t$) up to 12 indicate that the coupling runs, but not as fast as asymptotic freedom predicts. We discuss our program for studying the zero-temperature phenomenology of this theory.

  9. Walk well: a randomised controlled trial of a walking intervention for adults with intellectual disabilities: study protocol

    PubMed Central

    2013-01-01

    Background Walking interventions have been shown to have a positive impact on physical activity (PA) levels, health and wellbeing for adult and older adult populations. There has been very little work carried out to explore the effectiveness of walking interventions for adults with intellectual disabilities. This paper will provide details of the Walk Well intervention, designed for adults with intellectual disabilities, and a randomised controlled trial (RCT) to test its effectiveness. Methods/design This study will adopt a RCT design, with participants allocated to the walking intervention group or a waiting list control group. The intervention consists of three PA consultations (baseline, six weeks and 12 weeks) and an individualised 12 week walking programme. A range of measures will be completed by participants at baseline, post intervention (three months from baseline) and at follow up (three months post intervention and six months from baseline). All outcome measures will be collected by a researcher who will be blinded to the study groups. The primary outcome will be steps walked per day, measured using accelerometers. Secondary outcome measures will include time spent in PA per day (across various intensity levels), time spent in sedentary behaviour per day, quality of life, self-efficacy and anthropometric measures to monitor weight change. Discussion Since there are currently no published RCTs of walking interventions for adults with intellectual disabilities, this RCT will examine if a walking intervention can successfully increase PA, health and wellbeing of adults with intellectual disabilities. Trial registration ISRCTN: ISRCTN50494254 PMID:23816316

  10. JOINT LOADING OF LOWER EXTREMITIES DURING NORDIC WALKING COMPARED TO WALKING BASED ON KINETIC AND KINEMATIC DATA

    Microsoft Academic Search

    F. I. Kleindienst; F. Stief; F. Wedel; S. Campe; B. Krabbe

    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 differences in joint loading of lower extremities using an inverse dynamics approach between NW and Walking. In this experiment 15 subjects participated, who were already

  11. Six-Minute Walk Distance in Chronic Obstructive Pulmonary Disease Reproducibility and Effect of Walking Course Layout and Length

    Microsoft Academic Search

    Frank Sciurba; Gerard J. Criner; Shing M. Lee; Zab Mohsenifar; David Shade; William Slivka; Robert A. Wise

    The 6-minute walk test is used in clinical practice and clinical trials multicenter trial of lung volume reduction surgery compared of lung diseases; however, it is not clear whether replicate tests with medical treatment for advanced emphysema. The study need to be performed to assess performance. Furthermore, little is investigators conduct 6-minute walk tests in participants at known about the

  12. Biodiversity Walk and Talk (ID:216) A one hour walk around the university campus, stopping in various habitats to discuss

    E-print Network

    Harman, Neal.A.

    Biodiversity Walk and Talk (ID:216) Outline A one hour walk around the university campus, stopping will learn about the wealth of biodiversity on campus, including some important habitats and their associated for biodiversity and for humans. Location: Campus Available in Welsh: No Preparation required: Wear appropriate

  13. Energy expenditure of transfemoral amputees walking on a horizontal and tilted treadmill simulating different outdoor walking conditions.

    PubMed

    Starholm, Inger-Marie; Gjovaag, Terje; Mengshoel, Anne Marit

    2010-06-01

    Transfemoral amputees often report that walking on tilted pavements or on terrain with the prosthesis on the side of higher elevation is quite strenuous. This study investigates the energy expenditure of transfemoral amputees (n = 8) on a motorized treadmill, simulating different strenuous outdoor walking conditions. Oxygen uptake at self-selected speed of gait was measured during walking at three different treadmill positions: (i) Horizontal treadmill, (ii) 3% tilt in the sagittal plane and (iii) 3% tilt in both the sagittal and frontal plane of the treadmill. The difference in median values of oxygen uptake between position (i) and (ii) was 4.3%, and 16.4% between position (ii) and (iii) (p < or = 0.05, for both comparisons). The subjects utilized about 50% of their VO(2max) when walking in position (i) and (ii), with an increase to about 60% of their VO(2max) when walking in position (iii). Transfemoral amputees use significantly more energy when walking on a moderately tilted surface in the frontal plane compared to walking with a tilt in the sagittal plane. This is probably because the prosthetic leg becomes functionally too long when the walking surface is tilted sideways, and the transfemoral amputees adopt a more energy consuming gait pattern. PMID:20141493

  14. Influence of Neuromuscular Noise and Walking Speed on Fall Risk and Dynamic Stability in a 3D Dynamic Walking Model

    PubMed Central

    Roos, Paulien E.; Dingwell, Jonathan B.

    2013-01-01

    Older adults and those with increased fall risk tend to walk slower. They may do this voluntarily to reduce their fall risk. However, both slower and faster walking speeds can predict increased risk of different types of falls. The mechanisms that contribute to fall risk across speeds are not well known. Faster walking requires greater forward propulsion, generated by larger muscle forces. However, greater muscle activation induces increased signal-dependent neuromuscular noise. These speed-related increases in neuromuscular noise may contribute to the increased fall risk observed at faster walking speeds. Using a 3D dynamic walking model, we systematically varied walking speed without and with physiologically-appropriate neuromuscular noise. We quantified how actual fall risk changed with gait speed, how neuromuscular noise affected speed-related changes in fall risk, and how well orbital and local dynamic stability measures predicted changes in fall risk across speeds. When we included physiologically-appropriate noise to the ‘push-off’ force in our model, fall risk increased with increasing walking speed. Changes in kinematic variability, orbital, and local dynamic stability did not predict these speed-related changes in fall risk. Thus, the increased neuromuscular variability that results from increased signal-dependent noise that is necessitated by the greater muscular force requirements of faster walking may contribute to the increased fall risk observed at faster walking speeds. The lower fall risk observed at slower speeds supports experimental evidence that slowing down can be an effective strategy to reduce fall risk. This may help explain the slower walking speeds observed in older adults and others. PMID:23659911

  15. Localization of quantum walks induced by recurrence properties of random walks

    E-print Network

    Etsuo Segawa

    2012-07-03

    We study a quantum walk (QW) whose time evolution is induced by a random walk (RW) first introduced by Szegedy (2004). We focus on a relation between recurrent properties of the RW and localization of the corresponding QW. We find the following two fundamental derivations of localization of the QW. The first one is the set of all the $\\ell^2$ summable eigenvectors of the corresponding RW. The second one is the orthogonal complement, whose eigenvalues are $\\pm 1$, of the subspace induced by the RW. In particular, as a consequence, for an infinite half line, we show that localization of the QW can be ensured by the positive recurrence of the corresponding RWs, and also that the existence of only one self loop affects localization properties.

  16. 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

  17. Women with fibromyalgia walk with an altered muscle synergy.

    PubMed

    Pierrynowski, Michael R; Tiidus, Peter M; Galea, Victoria

    2005-11-01

    Most individuals can use different movement and muscle recruitment patterns to perform a stated task but often only one pattern is selected which optimizes an unknown global objective given the individual's neuromusculoskeletal characteristics. Patients with fibromyalgia syndrome (FS), characterized by their chronic pain, reduced physical work capacity and muscular fatigue, could exhibit a different control signature compared to asymptomatic control volunteers (CV). To test this proposal, 22 women with FS, and 11 CV, were assessed in a gait analysis laboratory. Each subject walked repeatedly at self-selected slow, comfortable, and fast walking speeds. The gait analysis provided, for each walk, each subject's stride time, length, and velocity, and ground reaction force, and lower extremity joint kinematics, moments and powers. The data were then anthropometrically scaled and velocity normalized to reduce the influence of subject mass, leg length, and walking speed on the measured gait outcomes. Similarities and differences in the two groups' scaled and normalized gait patterns were then determined. Results show that FS and CV walk with externally similar stride lengths, times, and velocities, and joint angles and ground reaction forces but they use internally different muscle recruitment patterns. Specifically, FS preferentially power gait using their hip flexors instead of their ankle plantarflexors. Interestingly, CV use a similar muscle fatiguing recruitment pattern to walk fast which parallels the common complaint of fatigue reported by FS walking at comfortable speed. PMID:16214660

  18. 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

  19. 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 mms(-1), the stride frequency levels off, the duty factor falls below 0.5, and Cataglyphis transitions to running with aerial phases. PMID:25829304

  20. 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.

  1. Rotor-Router Walks on Directed Covers of Graphs

    E-print Network

    Huss, Wilfried

    2012-01-01

    The aim of this paper is to study the behaviour of rotor-router walks on directed covers of finite graphs. The latter are also called in the literature trees with finitely many cone types or periodic trees. A rotor-router walk is a deterministic version of a random walk, in which the walker is routed to each of the neighbouring vertices in some fixed cyclic order. We study several quantities related to rotor-router walks such as: order of the rotor-router group, order of the root element in the rotor-router group and the connection with random walks. For random initial configurations of rotors, we also address the question of recurrence and transience of transfinite rotor-router walks. On homogeneous trees, the recurrence/transience was studied by Angel and Holroyd. We extend their theory and provide an example of a directed cover such that the rotor-router walk can be either recurrent or transient, depending only on the planar embedding of the periodic tree.

  2. Online Learning of a Full Body Push Recovery Controller for Omnidirectional Walking

    E-print Network

    Online Learning of a Full Body Push Recovery Controller for Omnidirectional Walking Seung-Joon Yi point based omnidirectional walk controller. Reinforcement learning is used to map the robot walking. Keywords: Bipedal Omnidirectional Walking, Full Body Push Recovery, Reinforcement Learning, Online Learning

  3. A Novel Approach for Generalising Walking Gaits across Embodiments and Behaviours

    E-print Network

    Vijayakumar, Sethu

    . The problem is formalised using a walking phase model, and the nullspace learning method is used to generaliseA Novel Approach for Generalising Walking Gaits across Embodiments and Behaviours Hsiu-Chin Lin1 of generalising walking gaits across different subjects and behaviours. Walking gaits are a result of complex

  4. Fuzzy Posture Control for Biped Walking Robot Based on Force Sensor for ZMP

    Microsoft Academic Search

    Kyu-Cheon Choil; Hyun-Jeong Lee; Min Cheol Lee

    2006-01-01

    In these days, biped walking robots are concentrated on a service robot. Biped walking robots are suitable in a human life work such as walking up and down stairs and crossing a threshold because they have two leg mechanisms like a human. However, it is very difficult subject that robot maintains balance in walking. One way to solve this problem

  5. SYSTEMS OF ONE-DIMENSIONAL RANDOM WALKS IN A COMMON RANDOM ENVIRONMENT

    E-print Network

    Peterson, Jonathon

    SYSTEMS OF ONE-DIMENSIONAL RANDOM WALKS IN A COMMON RANDOM ENVIRONMENT JONATHON PETERSON Abstract. We consider a system of independent one-dimensional random walks in a common random environment under-dimensional random walks in a common random environment. We modify the standard notion of random walks in random

  6. THE INHERENT WALKING DIRECTION DIFFERS FOR THE PROTHORACIC AND METATHORACIC LEGS OF STICK INSECTS

    Microsoft Academic Search

    ULRICH BASSLER; EVA FOTH; GERHARD BREUTEL

    SUMMARY On a slippery surface the forelegs of a decapitated stick insect walk forwards and the hindlegs, backwards. Animals with only forelegs but that are other- wise intact walk forwards, whereas animals with only hindlegs walk mostly backwards. Usually when intact animals start to walk, their hindlegs exert a rearwards thrust on the substrate, but occasionally the starting forces are

  7. Probabilistic Analysis of a Schroder Walk Generation Guy Louchard Olivier Roques y

    E-print Network

    Louchard, Guy

    Probabilistic Analysis of a Schroder Walk Generation Algorithm Guy Louchard #3; Olivier Roques y, we present a complete asymptotic probabilistic analysis of the cost of a Schroder walk generation analyze an algorithm proposed in [13] to generate Schroder walks of length 2n. Such a walk S(:) is also

  8. 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…

  9. Redirecting Walking and Driving for Natural Navigation in Immersive Virtual Environments

    Microsoft Academic Search

    Gerd Bruder; Victoria Interrante; Frank Steinicke

    2012-01-01

    Walking is the most natural form of locomotion for humans, and real walking interfaces have demonstrated their benefits for several navigation tasks. With recently proposed redirection techniques it becomes possible to overcome space limitations as imposed by tracking sensors or laboratory setups, and, theoretically, it is now possible to walk through arbitrarily large virtual environments. However, walking as sole locomotion

  10. 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

  11. Lateral Capture Steps for Bipedal Walking Marcell Missura and Sven Behnke

    E-print Network

    Behnke, Sven

    Lateral Capture Steps for Bipedal Walking Marcell Missura and Sven Behnke Abstract--Bipedal walkers are difficult to control, inherently unstable systems. Besides the complexity of the walking motion itself, the problem of complexity and the challenge of maintaining balance during walking. We decouple walking motion

  12. Improving Biped Walk Stability Using Real-time Corrective Human Feedback

    E-print Network

    Veloso, Manuela M.

    Improving Biped Walk Stability Using Real-time Corrective Human Feedback C¸ etin Meric¸li1 such a biped walk algorithm is non-trivial due to the complex dynamics of the walk process. In this paper, we walk algorithm as a black- box unit. We capture the corrective feedback signals delivered by a human

  13. Online Biped Walking Pattern Generation for Humanoid Robot KHR-3(KAIST Humanoid Robot - 3: HUBO)

    Microsoft Academic Search

    Ill-Woo Park; Jung-Yup Kim; Jun-Ho Oh

    2006-01-01

    This paper describes an algorithm about online walking pattern generation method, sensory feedback controllers for walking of humanoid robot platform KHR-3 (KAIST Humanoid Robot-3: HUBO) and experimental results. The walking pattern trajectories have continuity, smoothness in varying walking period and stride, and it has simple mathematical form which can be implemented easily. The gait trajectory algorithm is composed of two

  14. Quantum walk, entanglement and thermodynamic laws

    E-print Network

    Alejandro Romanelli

    2015-03-29

    We consider an special dynamics of a quantum walk (QW) on a line. Initially, the walker 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 ?rst 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 a function of the initial conditions. ii) the energy change is associated to a heat-transfer process.

  15. Random time averaged diffusivities for Lévy walks

    NASA Astrophysics Data System (ADS)

    Froemberg, D.; Barkai, E.

    2013-07-01

    We investigate a Lévy 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.

  16. Lazy random walks for superpixel segmentation.

    PubMed

    Shen, Jianbing; Du, Yunfan; Wang, Wenguan; Li, Xuelong

    2014-04-01

    We present a novel image superpixel segmentation approach using the proposed lazy random walk (LRW) algorithm in this paper. Our method begins with initializing the seed positions and runs the LRW algorithm on the input image to obtain the probabilities of each pixel. Then, the boundaries of initial superpixels are obtained according to the probabilities and the commute time. The initial superpixels are iteratively optimized by the new energy function, which is defined on the commute time and the texture measurement. Our LRW algorithm with self-loops has the merits of segmenting the weak boundaries and complicated texture regions very well by the new global probability maps and the commute time strategy. The performance of superpixel is improved by relocating the center positions of superpixels and dividing the large superpixels into small ones with the proposed optimization algorithm. The experimental results have demonstrated that our method achieves better performance than previous superpixel approaches. PMID:24565788

  17. Transience of Edge-Reinforced Random Walk

    NASA Astrophysics Data System (ADS)

    Disertori, Margherita; Sabot, Christophe; Tarrès, Pierre

    2015-06-01

    We show transience of the edge-reinforced random walk (ERRW) for small reinforcement in dimension {d?3} . This proves the existence of a phase transition between recurrent and transient behavior, thus solving an open problem stated by Diaconis in 1986. The argument adapts the proof of quasi-diffusive behavior of the supersymmetric (SuSy) hyperbolic model for fixed conductances by Disertori et al. (Commun Math Phys 300:435-486, 2010), using the representation of ERRW as a mixture of vertex-reinforced jump processes (VRJP) with independent gamma conductances, and the interpretation of the limit law of VRJP as a SuSy hyperbolic sigma model developed by Sabot and Tarrès (J Eur Math Soc, arXiv:1111.3991, 2015).

  18. Myths about the Country Walk case.

    PubMed

    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 the competing views of this case. Critics of this case advance three primary claims: (1) the positive STD test result from Frank Fuster's son was unreliable; (2) highly suggestive interviewing produced the children's claims; and (3) Frank Fuster's wife, Ileana, was coerced into testifying against her husband. On close examination, all three claims prove to be false. This article documents the reasons why these claims constitute myths and why those findings are significant in the larger debate on children as witnesses. PMID:18032242

  19. Universal behavior of quantum walks with long-range steps.

    PubMed

    Mülken, Oliver; Pernice, Volker; Blumen, Alexander

    2008-02-01

    Continuous-time quantum walks with long-range steps R(-gamma) (R being the distance between sites) on a discrete line behave in similar ways for all gamma > or =2 . This is in contrast to classical random walks, which for gamma>3 belong to a different universality class than for gamma < or =3 . We show that the average probabilities to be at the initial site after time t as well as the mean square displacements are of the same functional form for quantum walks with gamma =2, 4, and with nearest neighbor steps. We interpolate this result to arbitrary gamma > or =2 . PMID:18351997

  20. A note on branching random walks on finite sets

    Microsoft Academic Search

    Thomas Mountford; Rinaldo B. Schinazi

    2005-01-01

    We show that a branching random walk that is supercritical on\\u000aZd<\\/sup> is also supercritical, in a rather\\u000astrong sense, when restricted to a large enough finite ball of\\u000aZd<\\/sup>. This implies that the critical value\\u000aof branching random walks on finite balls converges to the\\u000acritical value of branching random walks on\\u000aZd<\\/sup> as the radius increases to infinity.

  1. Convergence of continuous-time quantum walks on the line

    E-print Network

    Alex D. Gottlieb

    2005-09-06

    The position density of a "particle" performing a continuous-time quantum walk on the integer lattice, viewed on length scales inversely proportional to the time t, converges (as t tends to infinity) to a probability distribution that depends on the initial state of the particle. This convergence behavior has recently been demonstrated for the simplest continuous-time random walk [see quant-ph/0408140]. In this brief report, we use a different technique to establish the same convergence for a very large class of continuous-time quantum walks, and we identify the limit distribution in the general case.

  2. Phenomenological picture of fluctuations in branching random walks.

    PubMed

    Mueller, A H; Munier, S

    2014-10-01

    We propose a picture of the fluctuations in branching random walks, which leads to predictions for the distribution of a random variable that characterizes the position of the bulk of the particles. We also interpret the 1/sqrt[t] correction to the average position of the rightmost particle of a branching random walk for large times t?1, computed by Ebert and Van Saarloos, as fluctuations on top of the mean-field approximation of this process with a Brunet-Derrida cutoff at the tip that simulates discreteness. Our analytical formulas successfully compare to numerical simulations of a particular model of a branching random walk. PMID:25375474

  3. Decoherence in a one-dimensional quantum walk

    SciTech Connect

    Annabestani, Mostafa; Abolhassani, Mohamad Reza [Department of Physics, Basic Sciences Faculty, Tarbiat Modarres University, Tehran (Iran, Islamic Republic of); Akhtarshenas, Seyed Javad [Department of Physics, University of Isfahan, Isfahan (Iran, Islamic Republic of); Quantum Optics Group, University of Isfahan, Isfahan (Iran, Islamic Republic of)

    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.

  4. A Walking Controller for a Powered Ankle Prosthesis

    PubMed Central

    Shultz, Amanda H.; Mitchell, Jason E.; Truex, Don; Lawson, Brian E.; Ledoux, Elissa; Goldfarb, Michael

    2015-01-01

    This paper describes a walking controller implemented on a powered ankle prosthesis prototype and assessed by a below-knee amputee subject on a treadmill at three speeds. The walking controller is a finite state machine which emulates a series of passive impedance functions at the joint in order to reproduce the behavior of a healthy joint. The assessments performed demonstrate the ability of the powered prosthesis prototype and walking controller to reproduce essential biomechanical aspects (i.e. joint angle, torque, and power profiles) of the healthy joint, especially relative to a passive prosthesis. PMID:25571414

  5. Differentiating ability in users of the ReWalk(TM) powered exoskeleton: an analysis of walking kinematics.

    PubMed

    Talaty, Mukul; Esquenazi, Alberto; Briceno, Jorge E

    2013-06-01

    The ReWalk(TM) powered exoskeleton assists thoracic level motor complete spinal cord injury patients who are paralyzed to walk again with an independent, functional, upright, reciprocating gait. We completed an evaluation of twelve such individuals with promising results. All subjects met basic criteria to be able to use the ReWalk(TM)--including items such as sufficient bone mineral density, leg passive range of motion, strength, body size and weight limits. All subjects received approximately the same number of training sessions. However there was a wide distribution in walking ability. Walking velocities ranged from under 0.1m/s to approximately 0.5m/s. This variability was not completely explained by injury level The remaining sources of that variability are not clear at present. This paper reports our preliminary analysis into how the walking kinematics differed across the subjects--as a first step to understand the possible contribution to the velocity range and determine if the subjects who did not walk as well could be taught to improve by mimicking the better walkers. PMID:24187286

  6. Study of activation in motor cortex during mental imagery of walking using fNIRS

    Microsoft Academic Search

    Yinlai Jiang; Shuoyu Wang; Renpeng Tan; Kenji Ishida; Takeshi Ando; Masakatsu G. Fujie

    2011-01-01

    A walking rehabilitation system is proposed which includes both muscle strength enhancement by walking rehabilitation machines and neurological rehabilitation by imaginary walking. In a previous study, we have demonstrated that the concentration of oxygenated hemoglobin (oxy-Hb) in motor area during imaginary walking was higher than that during real walking by means of tNlRS (functional Near­ InfraRed Spectroscopy). In order to

  7. Walking Control Algorithm of Biped Humanoid Robot on Uneven and Inclined Floor

    Microsoft Academic Search

    Jung-yup Kim; Ill-woo Park; Oh Jun-ho

    2007-01-01

    This paper describes walking control algorithm for the stable walking of a biped humanoid robot on an uneven and inclined\\u000a floor. Many walking control techniques have been developed based on the assumption that the walking surface is perfectly flat\\u000a with no inclination. Accordingly, most biped humanoid robots have performed dynamic walking on well designed flat floors.\\u000a In reality, however, a

  8. 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

  9. Online pose classification and walking speed estimation using handheld devices

    E-print Network

    Park, Jun-geun

    We describe and evaluate two methods for device pose classification and walking speed estimation that generalize well to new users, compared to previous work. These machine learning based methods are designed for the general ...

  10. Developing Questions for Gallery Walk to Engage Higher Order Thinking

    NSDL National Science Digital Library

    This section introduces Bloom's Taxonomy of Educational Objectives as an aid in writing questions for Gallery Walk (Bloom, 1964). Questions using the analysis, synthesis, and evaluation categories seem to work ...

  11. Activity of upper limb muscles during human walking.

    PubMed

    Kuhtz-Buschbeck, Johann P; Jing, Bo

    2012-04-01

    The EMG activity of upper limb muscles during human gait has rarely been studied previously. It was examined in 20 normal volunteers in four conditions: walking on a treadmill (1) with unrestrained natural arm swing (Normal), (2) while volitionally holding the arms still (Held), (3) with the arms immobilized (Bound), and (4) with the arms swinging in phase with the ipsilateral legs, i.e. opposite-to-normal phasing (Anti-Normal). Normal arm swing involved weak rhythmical lengthening and shortening contractions of arm and shoulder muscles. Phasic muscle activity was needed to keep the unrestricted arms still during walking (Held), indicating a passive component of arm swing. An active component, possibly programmed centrally, existed as well, because some EMG signals persisted when the arms were immobilized during walking (Bound). Anti-Normal gait involved stronger EMG activity than Normal walking and was uneconomical. The present results indicate that normal arm swing has both passive and active components. PMID:21945656

  12. Group velocity of discrete-time quantum walks

    SciTech Connect

    Kempf, A. [Department of Physics, University of Queensland, St. Lucia, Queensland 4072 (Australia); Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Portugal, R. [Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Laboratorio Nacional de Computacao Cientifica, Av. Getulio Vargas 333, Petropolis, Rio de Janeiro 25651-075, RJ (Brazil)

    2009-05-15

    We show that certain types of quantum walks can be modeled as waves that propagate in a medium with phase and group velocities that are explicitly calculable. Since the group and phase velocities indicate how fast wave packets can propagate causally, we propose the use of these wave velocities in our definition for the hitting time of quantum walks. Our definition of hitting time has the advantage that it requires neither the specification of a walker's initial condition nor of an arrival probability threshold. We give full details for the case of quantum walks on the Cayley graphs of Abelian groups. This includes the special cases of quantum walks on the line and on hypercubes.

  13. Astronaut Gordon Cooper walks to elevator to spacecraft 'Faith 7'

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Astronaut L. Gordon Cooper Jr. waited inside the transfer van for several minutes and then leaving the transfer van walked to the elevator which took him to the spacecraft 'Faith 7' atop the Atlas vehicle for his mission.

  14. 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

  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. Discrete-time quantum walk approach to state transfer

    SciTech Connect

    Kurzynski, Pawel [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2 (Singapore); Faculty of Physics, Adam Mickiewicz University, Umultowska 85, PL-61-614 Poznan (Poland); Wojcik, Antoni [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, PL-61-614 Poznan (Poland)

    2011-06-15

    We show that a quantum-state transfer, previously studied as a continuous-time process in networks of interacting spins, can be achieved within the model of discrete-time quantum walks with a position-dependent coin. We argue that, due to additional degrees of freedom, discrete-time quantum walks allow one to observe effects which cannot be observed in the corresponding continuous-time case. First, we study a discrete-time version of the engineered coupling protocol due to Christandl et al. [Phys. Rev. Lett. 92, 187902 (2004)] and then we discuss the general idea of conversion between continuous-time quantum walks and discrete-time quantum walks.

  17. Mixing times in quantum walks on two-dimensional grids

    SciTech Connect

    Marquezino, F. L.; Portugal, R.; Abal, G. [Laboratorio Nacional de Computacao Cientifica-LNCC Avenida Getulio Vargas 333, Petropolis, Rio de Janeiro 25651-075 (Brazil); Instituto de Fisica, Universidad de la Republica Casilla de Correo 30, Codigo Postal 11300, Montevideo (Uruguay)

    2010-10-15

    Mixing properties of discrete-time quantum walks on two-dimensional grids with toruslike boundary conditions are analyzed, focusing on their connection to the complexity of the corresponding abstract search algorithm. In particular, an exact expression for the stationary distribution of the coherent walk over odd-sided lattices is obtained after solving the eigenproblem for the evolution operator for this particular graph. The limiting distribution and mixing time of a quantum walk with a coin operator modified as in the abstract search algorithm are obtained numerically. On the basis of these results, the relation between the mixing time of the modified walk and the running time of the corresponding abstract search algorithm is discussed.

  18. Tail Kinematics of Juvenile Common Snapping Turtles during Aquatic Walking

    E-print Network

    Blob, Richard W.

    juvenile Common Snapping Turtles (Chelydra serpentina) during aquatic walking. Common Snapping Turtles hold Macrochelys temminicki and three Common Snapping Turtle species in the genus Chelydra; Phillips et al., 1996

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

    SciTech Connect

    Kollar, B.; Kiss, T. [Department of Quantum Optics and Quantum Information, Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Konkoly-Thege Miklos ut 29-33, H-1121 Budapest (Hungary); Stefanak, M.; Jex, I. [Department of Physics, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Brehova 7, 115 19 Praha 1--Stare Mesto (Czech Republic)

    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.

  20. Kirkman's Schoolgirls Wearing Hats and Walking through Fields of Numbers

    E-print Network

    Brown, Ezra

    of a school walk out three abreast for seven days in succes- sion: it is required to arrange them daily so] is one of the starting points for what has become the vast modern field of combinatorial design theory

  1. Markov matrix analysis of random walks in disordered continuous media

    NASA Astrophysics Data System (ADS)

    Lee, Sang Bub; Nakanishi, Hisao

    1999-07-01

    We study by a Markov matrix analysis of the equivalent random walks the dynamic properties of continuous media consisting of both correlated and uncorrelated equal-size spheres. We employ a blind ant random-walk model using the rule that a walker jumps among centers of the directly connected spherical particles on an infinite network. The dominant eigenvalues and eigenvectors of the transition probability matrix of the random walks are calculated, yielding estimates of the spectral dimension d s and the fractal dimension d w of random walks on the continuous network. We find that, for the present model, the estimates are very close to the corresponding lattice percolation values, though only after the finite-size effects have been carefully taken into account. We also show that the finite-size scaling of the largest nontrivial eigenvalues holds for our model with the same exponents as for the lattice percolation.

  2. Walk This Way! Taking Steps for Pedestrian Safety

    MedlinePLUS

    ... CDC Features Walk This Way! Taking Steps for Pedestrian Safety Language: English Español (Spanish) Recommend on Facebook Tweet ... following resources offer tips on how to promote pedestrian safety for children—a critical step in preventing child ...

  3. Human walking model predicts joint mechanics, electromyography and mechanical economy

    E-print Network

    Endo, Ken

    In this paper, we present an under-actuated model of human walking, comprising only a soleus muscle and flexion/extension monoarticular hip muscles. The remaining muscle groups of the human leg are modeled using quasi-passive, ...

  4. 1. VIEW LOOKING SOUTH, SHOWING AFRAME OF WALKING BEAM ENGINE, ...

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

    1. VIEW LOOKING SOUTH, SHOWING A-FRAME OF WALKING BEAM ENGINE, BOW END TO LEFT Edward Larrabee, photographer, November 1984 - Shooters Island, Ships Graveyard, Vessel No. 53, Newark Bay, Staten Island (subdivision), Richmond County, NY

  5. Gallery Walk Questions about Energy and Material Cycles

    NSDL National Science Digital Library

    created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about energy and material cycles. The questions are organized according to ...

  6. 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

  7. On time scale invariance of random walks in confined space.

    PubMed

    Bearup, Daniel; Petrovskii, Sergei

    2015-02-21

    Animal movement is often modelled on an individual level using simulated random walks. In such applications it is preferable that the properties of these random walks remain consistent when the choice of time is changed (time scale invariance). While this property is well understood in unbounded space, it has not been studied in detail for random walks in a confined domain. In this work we undertake an investigation of time scale invariance of the drift and diffusion rates of Brownian random walks subject to one of four simple boundary conditions. We find that time scale invariance is lost when the boundary condition is non-conservative, that is when movement (or individuals) is discarded due to boundary encounters. Where possible analytical results are used to describe the limits of the time scaling process, numerical results are then used to characterise the intermediate behaviour. PMID:25481837

  8. 7. Photocopy of a 1942 architectural drawing titled: 'Covered Walks. ...

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

    7. Photocopy of a 1942 architectural drawing titled: 'Covered Walks. Typical Elevations and Sections.' 10-31-42 - Madigan Hospital, Corridors & Ramps, Bounded by Wilson & McKinley Avenues & Garfield & Lincoln Streets, Tacoma, Pierce County, WA

  9. The hydrodynamics of water-walking insects and spiders

    E-print Network

    Hu, David L., 1979-

    2006-01-01

    We present a combined experimental and theoretical investigation of the numerous hydrodynamic propulsion mechanisms employed by water-walking arthropods (insects and spiders). In our experimental study, high speed ...

  10. Localization Transition of Biased Random Walks on Random Networks

    NASA Astrophysics Data System (ADS)

    Sood, Vishal; Grassberger, Peter

    2007-08-01

    We study random walks on large random graphs that are biased towards a randomly chosen but fixed target node. We show that a critical bias strength bc exists such that most walks find the target within a finite time when b>bc. For bwalks drift off to infinity before hitting the target. The phase transition at b=bc is a critical point in the sense that quantities such as the return probability P(t) show power laws, but finite-size behavior is complex and does not obey the usual finite-size scaling ansatz. By extending rigorous results for biased walks on Galton-Watson trees, we give the exact analytical value for bc and verify it by large scale simulations.

  11. Tunneling effects in a one-dimensional quantum walk

    E-print Network

    Mostafa Annabestani; Seyed Javad Akhtarshenas; Mohamad Reza Abolhassani

    2010-04-25

    In this article we investigate the effects of shifting position decoherence, arisen from the tunneling effect in the experimental realization of the quantum walk, on the one-dimensional discreet time quantum walk. We show that in the regime of this type of noise the quantum behavior of the walker does not fade, in contrary to the coin decoherence for which the walker undergos the quantum-to-classical transition even for weak noise. Particularly, we show that the quadratic dependency 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 decoherent one-dimensional quantum walk in terms of the corresponding coherent probabilities, and show that this type of decoherence smooths the probability distribution.

  12. Robust Execution of Bipedal Walking Tasks From Biomechanical Principles

    E-print Network

    Hofmann, Andreas

    2006-04-28

    Effective use of robots in unstructured environments requires that they have sufficient autonomy and agility to execute task-level commands successfully. A challenging example of such a robot is a bipedal walking machine. ...

  13. Walking Box Ranch An endeavor, an economic pursuit, a retreat.

    E-print Network

    Hemmers, Oliver

    land offered new opportunities for large cattle ranches. Hollywood stars Clara Bow and Rex Bell came at Walking Box Ranch, the Hollywood-star couple raised a family in their desert sanctuary. Government

  14. Enumeration of self-avoiding walks on the square lattice

    Microsoft Academic Search

    Iwan Jensen

    2004-01-01

    We describe a new algorithm for the enumeration of self-avoiding walks on the square lattice. Using up to 128 processors on a HP Alpha server cluster we have enumerated the number of self-avoiding walks on the square lattice to length 71. Series for the metric properties of mean-square end-to-end distance, mean-square radius of gyration and mean-square distance of monomers from

  15. Learning Walking Patterns for Kinematically Complex Robots Using Evolution Strategies

    Microsoft Academic Search

    Malte Römmermann; Mark Edgington; Jan Hendrik Metzen; Jose De Gea; Yohannes Kassahun; Frank Kirchner

    2008-01-01

    Manually developing walking patterns for kinematically complex robots can be a challenging and time-consuming task. In order\\u000a to automate this design process, a learning system that generates, tests, and optimizes different walking patterns is needed,\\u000a as well as the ability to accurately simulate a robot and its environment. In this work, we describe a learning system that\\u000a uses the CMA-ES

  16. 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

  17. Central Limit Theorem for Branching Random Walks in Random Environment

    E-print Network

    Nobuo Yoshida

    2007-12-05

    We consider branching random walks in $d$-dimensional integer lattice with time-space i.i.d. offspring distributions. When $d \\ge 3$ and the fluctuation of the environment is well moderated by the random walk, we prove a central limit theorem for the density of the population, together with upper bounds for the density of the most populated site and the replica overlap. We also discuss the phase transition of this model in connection with directed polymers in random environment.

  18. Random walk approximation for the radial dose dependence

    NASA Astrophysics Data System (ADS)

    Surdutovich, E.; Solov'yov, A. V.

    2012-09-01

    We investigate the properties of the radial distribution of energy deposited by ions, calculated using a random walk approach, which is an important analytical tool for solving transport problems. This investigation is motivated by the desire to understand the range of applicability of the random walk approximation for problems related to radiation damage assessment. We study the radial dose at small and moderate distances and compare our results to the results of Monte Carlo simulations.

  19. The Integument of Water-walking Arthropods: Form and Function

    Microsoft Academic Search

    John W. M. Bush; David L. Hu; Manu Prakash

    2007-01-01

    We develop a coherent view of the form and function of the integument of water-walking insects and spiders by reviewing biological work on the subject in light of recent advances in surface science. Particular attention is given to understanding the complex nature of the interaction between water-walking arthropods and the air–water surface. We begin with a discussion of the fundamental

  20. 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

  1. Walking performance in people with diabetic neuropathy: benefits and threats

    Microsoft Academic Search

    R. V. Kanade; R. W. M. van Deursen; K. Harding; P. Price

    2006-01-01

    Aims\\/hypothesis  Walking is recommended as an adjunct therapy to diet and medication in diabetic patients, with the aim of improving physical fitness, glycaemic control and body weight reduction. Therefore we evaluated walking activity on the basis of capacity, performance and potential risk of plantar injury in the diabetic population before it can be prescribed safely.Subjects, materials and methods  Twenty-three subjects with diabetic

  2. Forced Walking Prepartum for Dairy Cows of Different Ages

    Microsoft Academic Search

    R. C. Lamb; M. J. Anderson; J. L. Walters

    1981-01-01

    Fifty-three 2-yr-old Holstein heifers and 63 cows from 3 to 7 yr old were exercised 5 days\\/wk for 8 wk before calving. Three treatments were: 1) con- trol (no forced exercise); 2) walk 1.6 km\\/day; and 3) walk 8.0 km\\/day. Exer- cise was at 4.0 km\\/h in a circular lane with a motor-driven gate. Daily feed in- take and weekly

  3. Site and neighborhood environments for walking among older adults

    Microsoft Academic Search

    Zhe Wang; Chanam Lee

    2010-01-01

    Walking has significant health and mobility benefits for older adults. Previous environment–walking studies have focused on neighborhood environments, overlooking proximate site-level characteristics. This study examines both the neighborhood and site-level environments.A survey was conducted with 114 older adults from five assisted-living facilities in Houston, TX. A subset of 61 participants’ environments was examined using Geographic Information Systems (GIS). Multivariate analyses

  4. Elasticity and movements of the cockroach tarsus in walking

    Microsoft Academic Search

    S. F. Frazier; G. S. Larsen; D. Neff; L. Quimby; M. Carney; R. A. DiCaprio; S. N. Zill

    1999-01-01

    Anatomical, kinematic and ablation studies were performed to evaluate the contribution of elasticity in use of the cockroach\\u000a tarsus (foot) in walking. The distal tarsus (claws and arolium) engages the substrate during the stance phase of walking by\\u000a the action of a single muscle, the retractor unguis. Kinematic and ablation studies demonstrated that tarsal disengagement\\u000a occurs at the end of

  5. Ising model observables and non-backtracking walks

    SciTech Connect

    Helmuth, Tyler, E-mail: jhelmt@math.ubc.ca [Department of Mathematics, The University of British Columbia, Vancouver, British Columbia V6T 1Z2 (Canada)

    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.

  6. MODELING BILL'S GAIT: ANALYSIS AND PARAMETRIC SYNTHESIS OF WALKING SOUNDS

    Microsoft Academic Search

    PERRY R. COOK

    2002-01-01

    This paper presents algorithms and systems for automatic analysis and parametric synthesis of walking and other (gesture-rate) periodically modulated noisy sounds. A recording of walking is analyzed, extracting the gait (tempo and left\\/right asymmetries), heel-toe events, etc. Linear prediction is used to extract the basic resonances. Wavelet decomposition is performed, and a high frequency-subband is used to calculate statistics for

  7. Reduced plantar sensation causes a cautious walking pattern

    Microsoft Academic Search

    Eric Eils; Susann Behrens; Oliver Mers; Lothar Thorwesten; Klaus Völker; Dieter Rosenbaum

    2004-01-01

    The aim of this study was to investigate the influence of reduced plantar sensation on gait patterns during walking in 20 healthy subjects (25.9±1.2 years, 61.6±11.5kg, 178±9.5cm) with no history of sensory disorders. Force plate measurements, electromyography (EMG) measurements and a three-dimensional movement analysis were performed simultaneously during barefoot walking before and after reduction of plantar sensation using an ice

  8. 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

  9. Walking with Increased Ankle Pushoff Decreases Hip Muscle Moments

    PubMed Central

    Lewis, Cara L.; Ferris, Daniel P.

    2008-01-01

    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 1.25 m/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 compensate for hip muscle weakness or injury and reduce hip joint forces. PMID:18606419

  10. Higher-intensity treadmill walking during rehabilitation after stroke in feasible and not detrimental to walking pattern or quality: a pilot randomized trial

    Microsoft Academic Search

    Suzanne S Kuys; Sandra G Brauer; Louise Ada

    2011-01-01

    Objective: To determine whether higher-intensity treadmill walking during rehabilitation in those newly able to walk after stroke is feasible, is detrimental to walking or is beneficial.Design: A single-blind, randomized trial.Setting: Two rehabilitation units.Participants: Thirty people with first stroke.Interventions: Experimental group received 30 minutes of higher-intensity treadmill walking, three times per week for six weeks, in addition to usual physiotherapy. Control

  11. 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.

  12. Neural decoding of treadmill walking from noninvasive electroencephalographic signals.

    PubMed

    Presacco, Alessandro; Goodman, Ronald; Forrester, Larry; Contreras-Vidal, Jose Luis

    2011-10-01

    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

  13. Sick man walking: Perception of health status from body motion.

    PubMed

    Sundelin, T; Karshikoff, B; Axelsson, E; Höglund, C Olgart; Lekander, M; Axelsson, J

    2015-08-01

    An ability to detect subtle signs of sickness in others would be highly beneficial, as it would allow for behaviors that help us avoid contagious pathogens. Recent findings suggest that both animals and humans are able to detect distinctive odor signals of individuals with activated innate immune responses. This study tested whether an innate immune response affects a person's walking speed and whether other people perceive that person as less healthy. 43 subjects watched films of persons who were experiencing experimental immune activation, and rated the walking individuals in the films with respect to health, tiredness, and sadness. Furthermore, the walking speed in the films was analyzed. After LPS injections, participants walked more slowly and were perceived as less healthy and more tired as compared to when injected with placebo. There was also a trend for the subjects to look sadder after LPS injection than after placebo. Furthermore, there were strong associations between walking speed and the appearance of health, tiredness, and sadness. These findings support the notion that walking speed is affected by an activated immune response, and that humans may be able to detect very early signs of sickness in others by merely observing their gait. This ability is likely to aid both a "behavioral immune system", by providing more opportunities for adaptive behaviors such as avoidance, and the anticipatory priming of biochemical immune responses. PMID:25801061

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

    PubMed Central

    Bonnet, Vincent; Ramdani, Sofiane; Azevedo-Coste, Christine; Fraisse, Philippe; Mazzà, 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

  15. Quantum Random Walks and the Graph Isomorphism Problem

    NASA Astrophysics Data System (ADS)

    Rudinger, Kenneth; King Gamble, John; Wellons, Mark; Friesen, Mark; Bach, Eric; Joynt, Robert; Coppersmith, S. N.

    2012-02-01

    We investigate the quantum dynamics of particles on graphs (``quantum walk''), with the aim of developing quantum algorithms for determining whether or not two graphs are isomorphic. We investigate such walks on strongly regular graphs (SRGs), a class of graphs with high symmetry. We explore the effects of particle number and interaction range on a walk's ability to distinguish non-isomorphic graphs. We numerically find that both non-interacting three-boson and three-fermion continuous time walks have the same distinguishing power on a dataset of 70,712 pairs of SRGs, each distinguishing over 99.6% of the pairs. We also find that increasing to four non-interacting particles further increases distinguishing power on this dataset. While increasing particle number increases distinguishing power, we prove that any walk of a fixed number of non-interacting particles cannot distinguish all SRGs. We numerically find that increasing particle number and increasing interaction range both result in increased distinguishing power of non-SRGs that are designed to be indistinguishable to the hard-core two-boson walk.

  16. 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

  17. fNIRS Study of Walking and Walking While Talking in Young and Old Individuals

    PubMed Central

    Mahoney, Jeannette R.; Izzetoglu, Meltem; Izzetoglu, Kurtulus; Onaral, Banu; Verghese, Joe

    2011-01-01

    Background. Evidence suggests that gait is influenced by higher order cognitive and cortical control mechanisms. However, less is known about the functional correlates of cortical control of gait. Methods. Using functional near-infrared spectroscopy, the current study was designed to evaluate whether increased activations in the prefrontal cortex (PFC) were detected in walking while talking (WWT) compared with normal pace walking (NW) in 11 young and 11 old participants. Specifically, the following two hypotheses were evaluated: (a) Activation in the PFC would be increased in WWT compared with NW. (b) The increase in activation in the PFC during WWT as compared with NW would be greater in young than in old participants. Results. Separate linear mixed effects models with age as the two-level between-subject factor, walking condition (NW vs WWT) as the two-level repeated within-subject factor, and HbO2 levels in each of the 16 functional near-infrared spectroscopy channels as the dependent measure revealed significant task effects in 14 channels, indicating a robust bilateral increased activation in the PFC in WWT compared with NW. Furthermore, the group-by-task interaction was significant in 11 channels with young participants showing greater WWT-related increase in HbO2 levels compared with the old participants. Conclusions. This study provided the first evidence that oxygenation levels are increased in the PFC during WWT compared with NW in young and old individuals. This effect was modified by age suggesting that older adults may underutilize the PFC in attention-demanding locomotion tasks. PMID:21593013

  18. Predictors of Short and Long-Term Adherence to a Daily Walking Program in Persons With Alzheimer’s Disease

    Microsoft Academic Search

    Susan M. McCurry; Kenneth C. Pike; Rebecca G. Logsdon; Michael V. Vitiello; Eric B. Larson; Linda Teri

    2010-01-01

    Objective: To examine factors associated with adherence to a walking program in community-dwelling individuals with Alzheimer’s disease (AD). Methods: Data were analyzed for 66 participants with AD asked to walk 30 continuous minutes per day. Adherence data (number of days walked, minutes walked, days walked 30+ minutes) were obtained from daily logs. Predictor variables included age, spousal relationship, health limitations,

  19. Walking the line: a randomised trial on the effects of a short term walking programme on cognition in dementia

    Microsoft Academic Search

    L. H. P. Eggermont; D. F. Swaab; E. M. Hol; E. J. A. Scherder

    2009-01-01

    Background:Walking has proven to be beneficial for cognition in healthy sedentary older people. The aim of this study was to examine the effects of a walking intervention on cognition in older people with dementia.Methods:97 older nursing home residents with moderate dementia (mean age 85.4 years; 79 female participants; mean Mini-Mental State Examination 17.7) were randomly allocated to the experimental or

  20. Hip flexor fatigue limits walking in Charcot-Marie-Tooth disease

    PubMed Central

    RAMDHARRY, GITA M.; DAY, BRIAN L.; REILLY, MARY M.; MARSDEN, JONATHAN F.

    2013-01-01

    Charcot–Marie–Tooth (CMT) disease results in distal lower limb weakness that affects walking. In this study we assess the role of the hip flexors in compensating for distal weakness while walking and the effects of prolonged walking on these putative compensatory strategies. Eighteen subjects with CMT disease were compared with 14 matched controls while they walked on a treadmill to a predetermined point of perceived effort. A significant reduction was observed in peak hip flexor velocity during walking and hip flexor maximal voluntary contraction. In a second session following selective fatigue of the hip flexors, hip flexor velocity decreased immediately on walking, and walking duration was greatly reduced. This study suggests that hip flexors compensate for distal weakness and that fatigue in the hip flexors can limit walking duration. Treatments directed toward improving proximal muscle strength may therefore help to delay onset of hip flexor fatigue and thus prolong walking duration. PMID:19405092