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1

Walking abnormalities  

MedlinePLUS

Gait abnormalities ... of how a person walks is called the gait. Many different types of walking problems occur without ... Some walking abnormalities have been given names: Propulsive gait -- a stooped, stiff posture with the head and ...

2

Walking Problems  

MedlinePLUS

... get around, and exercise. Having a problem with walking can make daily life more difficult. The pattern ... an abnormal gait and lead to problems with walking. These include: Injuries, diseases, or abnormal development of ...

3

Gallery Walk  

NSDL National Science Digital Library

Compiled by Mark Francek (more info) at Central Michigan University (more info) What is Gallery Walk? --a discussion technique for active engagement Gallery Walk gets students out of their chairs and actively ...

Francek, Mark

4

Walking the walk  

SciTech Connect

Earth Day, celebrated this April, brought out a spate of press conferences, fairs and media spots. The White House announced its plans to green itself by incorporating energy efficiency and recycling, and Vice President Gore and Energy Secretary O`Leary announced the President`s Executive Order, which mandates the use of energy efficiency in federal facilities with solar as a high-profile option. At the White House itself, however, no solar application has yet been selected for installation. Another Earth Day media spot showed how the nation`s utility companies have joined Secretary O`Leary`s Climate Challenge, an ambitious voluntary program to cut greenhouse-gas emissions. During Earth Day 1994, it became clear how many houses use solar water heating and how often photovoltaics is used to power road signs and sign boards, telephones and repeaters, and for cathodic protection and security lighting. Solar energy is expanding. But if it is to become a truly everyday technology, more institution, governments, businesses and individual consumers are going to have to walk the walk. This means that Earth Day will have to last longer, environmental concerns must become more genuine, and the focus of government and business decisions must be more long-term.

Butler, B.

1994-12-31

5

Gallery Walk  

NSDL National Science Digital Library

This site from Illuminations presents a lesson plan that requires students to use a gallery walk to share their mathematical conclusions. A gallery walk allows students to view the work of other students in the class and to explain their own work.

Illuminations

6

Walking Perception by Walking Observers  

ERIC Educational Resources Information Center

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

Jacobs, Alissa; Shiffrar, Maggie

2005-01-01

7

Walking stick  

NSDL National Science Digital Library

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.

Clinton Robertson (None;); Charles Robertson (None;)

2006-09-23

8

Random Walk Polynomials and Random Walk Measures.  

National Technical Information Service (NTIS)

Random walk polynomials and random walk measures play a prominent role in the analysis of a class of Markov chains called random walks. Without any reference to random walks, however, a random walk polynomial sequence can be defined, and is defined in thi...

E. A. Vandoorn P. Schrijner

1991-01-01

9

Random Walk Polynomials and Random Walk Measures.  

National Technical Information Service (NTIS)

Random walk polynomials and random walk measures play a prominent role in the analysis of a class of Markov chains called random walks. Without any reference to random walks, however, a random walk polynomial sequence can be defined (and will be defined i...

E. A. van Doorn P. Schrijner

1991-01-01

10

Walk Score  

NSDL National Science Digital Library

If you're looking for a walkable community, is there a way to determine which neighborhood might be best for you? Interested parties might use the Walk Score to get a basic sense of nearby amenities, such as grocery stores, parks, restaurants, and so on. Visitors can type in a street address or neighborhood, and they can find out the location's cumulative Walk Score. Also, visitors can use the site to find out about potential nearby rental properties, if they are so inclined. This site is compatible with all operating systems.

2012-04-27

11

Earth Walk  

NSDL National Science Digital Library

In this hands-on and feet-on excursion, learners take a science walk to visualize the planet's immense size and numerous structures, without the usual scale and ratio dimensions found in most textbooks. Learners also compare their body's height to a scaled-down Earth.

Muller, Eric

1995-01-01

12

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...

13

Quantum random walks without walking  

SciTech Connect

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.

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

2009-12-15

14

Nature Walk  

NSDL National Science Digital Library

In this activity, learners take an indoor nature walk and discover various objects that have been brought in from the outdoor environment. In preparation for the activity, an educator places natural and man-made items around a room for learners to discover. Learners examine what they find and make notes about what they see and smell, how they (the learners) feel, and what each item looks like (including sketches). Then the group addresses the topic of "Leave No Trace" as it applies to a real nature walk. This would be a great activity before a field trip to a park, arboretum, or other outdoor environment, and can be done with one learner, a class, or even a large group at a family science event.

National 4-H Council

2009-01-01

15

Randomized Random Walk on a Random Walk.  

National Technical Information Service (NTIS)

This paper discusses generalizations of the model introduced by Kehr and Kunter of the random walk of a particle on a one-dimensional chain which in turn has been constructed by a random walk procedure. The superimposed random walk is randomised in time a...

P. A. Lee

1983-01-01

16

Walking molecules.  

PubMed

Movement is intrinsic to life. Biologists have established that most forms of directed nanoscopic, microscopic and, ultimately, macroscopic movements are powered by molecular motors from the dynein, myosin and kinesin superfamilies. These motor proteins literally walk, step by step, along polymeric filaments, carrying out essential tasks such as organelle transport. In the last few years biological molecular walkers have inspired the development of artificial systems that mimic aspects of their dynamics. Several DNA-based molecular walkers have been synthesised and shown to walk directionally along a track upon sequential addition of appropriate chemical fuels. In other studies, autonomous operation--i.e. DNA-walker migration that continues as long as a complex DNA fuel is present--has been demonstrated and sophisticated tasks performed, such as moving gold nanoparticles from place-to-place and assistance in sequential chemical synthesis. Small-molecule systems, an order of magnitude smaller in each dimension and 1000× smaller in molecular weight than biological motor proteins or the walker systems constructed from DNA, have also been designed and operated such that molecular fragments can be progressively transported directionally along short molecular tracks. The small-molecule systems can be powered by light or chemical fuels. In this critical review the biological motor proteins from the kinesin, myosin and dynein families are analysed as systems from which the designers of synthetic systems can learn, ratchet concepts for transporting Brownian substrates are discussed as the mechanisms by which molecular motors need to operate, and the progress made with synthetic DNA and small-molecule walker systems reviewed (142 references). PMID:21416072

von Delius, Max; Leigh, David A

2011-03-17

17

Generation of humanoid walking pattern based on human walking measurement  

Microsoft Academic Search

Walking pattern generation has been a crucial issue for humanoid robot. To generate more natural walking patterns, and determine parameters more reasonably, this paper presents a method for humanoid walking pattern generation based on human walking characteristics. The characteristics of human walking parameters were obtained by capturing and analyzing human walking data. Walking pattern parameters are determined by using these

Qiang Huang; Zhangguo Yu; Weimin Zhang; Xingguang Duan; Yuancan Huang; Kejie Li

2008-01-01

18

Fire-Walking  

ERIC Educational Resources Information Center

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

Willey, David

2010-01-01

19

Fire-walking  

NASA Astrophysics Data System (ADS)

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

Willey, David

2010-09-01

20

Walking the Walk: A Phenomenological Study of Long Distance Walking  

Microsoft Academic Search

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

Lee Crust; Richard Keegan; David Piggott; Christian Swann

2011-01-01

21

Talking the talk on walking the walk  

Microsoft Academic Search

Background  The Multiple Sclerosis Walking Scale (MSWS-12) was developed to measure the impact of multiple sclerosis on walking. Many\\u000a other disabling neurological conditions affect patients’ ability to walk, and a generic measure of walking could provide valuable\\u000a insights into patients’ perceptions in clinical trials and epidemiological studies as well as routine clinical practice.\\u000a \\u000a \\u000a \\u000a Objective  To evaluate the clinical usefulness and psychometric properties

A. Holland; R. J. O’Connor; A. J. Thompson; E. D. Playford; J. C. Hobart

2006-01-01

22

Gait or Walking Problems  

MedlinePLUS

... 1 Gait or Walking Problems the basic facts multiPle sclerosis many people with ms will experience difficulty with ... rock university in Pennsylvania, with long experience in multiple sclerosis. “This makes walking problems difficult to address.” Difficult, ...

23

Limit Cycle Walking  

Microsoft Academic Search

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

M. Wisse; D. G. E. Hobbelen

2007-01-01

24

Passive Dynamic Walking  

Microsoft Academic Search

There exists a class of two-legged machines for which walking is a natural dynamic mode. Once started on a shallow slope, a machine of this class will settle into a steady gait quite comparable to human walking, without active control or en ergy input. Interpretation and analysis of the physics are straightforward; the walking cycle, its stability, and its sensi

Tad Mcgeer

1990-01-01

25

Walk This Way  

ERIC Educational Resources Information Center

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

Mason, Nick

2007-01-01

26

Walking for Little Children. Creative Workshops for Teaching Walking & Wellness.  

ERIC Educational Resources Information Center

|This walking primer is intended for teachers and parents who are interested in early childhood wellness. The manual contains 40 photographs and 60 fitness walking exercises, walking games and fun workshops in nutrition and children's weight control, walking field trips, and guidance for the walking teacher. Attention is given to winning parental…

Sweetgall, Robert; Neeves, Robert

27

Quantum walks on cycles  

NASA Astrophysics Data System (ADS)

We consider asymptotic behaviour of a Hadamard walk on a cycle. For the walk which starts with a state in which all the probability is concentrated on one node, we find the explicit formula for the limiting distribution and discuss its asymptotic behaviour when the length of the cycle tends to infinity. We also demonstrate that for a carefully chosen initial state, the limiting distribution of a quantum walk on cycle can lie further away from the uniform distribution than its initial state.

Bednarska, Malgorzata; Grudka, Andrzej; Kurzy?ski, Pawel; Luczak, Tomasz; Wójcik, Antoni

2003-10-01

28

Enhanced: Walking Made Simple  

NSDL National Science Digital Library

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.

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

2005-04-01

29

Toe Walking in Children  

MedlinePLUS

... cases, the doctor may do an in-depth gait analysis or an exam known as electromyography (EMG). During ... et al. The toe walking tool: A novel method for assessing idiopathic toe walking children. Gait & Posture. 2010;32:508. Cerebral palsy: Hope through ...

30

Walking cavity solitons  

SciTech Connect

A family of walking solitons is obtained for the degenerate optical parametric oscillator below threshold. The loss-driven mechanism of velocity selection for these structures is described analytically and numerically. Our approach is based on understanding the role played by the field momentum and generic symmetry properties and, therefore, it can be easily generalized to other dissipative multicomponent models with walk off.

Skryabin, Dmitry V.; Champneys, Alan R.

2001-06-01

31

Walking machines for space  

NASA Astrophysics Data System (ADS)

A study of a new walking machine model differing from existing walking machines both in geometry and control is presented. The main criteria used in the model are not technical principles as used in existing walking machines, but rather biological principles found in insects, the living prototypes of walking machines. The goal of this method is to obtain a harmonic gait which is very robust against disturbances and therefore is suitable to be used on uneven ground found on planets. The geometry, the kinematics and the kinetics of the walking machine model is introduced and the control is explained. Experimental results of this concept tested on a single laboratory leg are shown to prove the robustness of the controller.

Eltze, J.; Weidemann, H.-J.; Pfeiffer, F.

1993-01-01

32

Anyonic quantum walks  

SciTech Connect

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.

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

33

Walking on Mars  

NASA Astrophysics Data System (ADS)

Sometime in the near future humans may walk in the reduced gravity of Mars. Gravity plays an essential role in walking. On Earth, the body uses gravity to `fall forwards' at each step and then the forward speed is used to restore the initial height in a pendulum-like mechanism. When gravity is reduced, as on the Moon or Mars, the mechanism of walking must change. Here we investigate the mechanics of walking on Mars onboard an aircraft undergoing gravity-reducing flight profiles. The optimal walking speed on Mars will be 3.4 km h-1 (down from 5.5 km h-1 on Earth) and the work done per unit distance to move the centre of mass will be half that on Earth.

Cavagna, G. A.; Willems, P. A.; Heglund, N. C.

1998-06-01

34

Symmetry in quantum walks  

NASA Astrophysics Data System (ADS)

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. The hitting time for a classical random walk on a connected graph will always be finite. We show that, by contrast, 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, which for discrete time quantum walks is that the degeneracy of the evolution operator be greater than the degree of the graph. 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 cause the walk to also be confined to a subspace of the original Hilbert space for cartain 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. We give an explicit construction of the quotient graph for any subgroup H of the automorphism group. 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. 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.

Krovi, Hari

35

6.EE Morning Walk  

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: Sierra walks her dog Pepper twice a day. Her evening walk is two and a half times as far as her morning walk. At the end of the week she tells her mom,...

36

The Self-Avoiding Walk  

Microsoft Academic Search

Simple random walk is well understood. However, if we condition a random walk not to intersect itself, so that it is a self-avoiding walk, then it is much more di-- cult to analyse and many of the important mathematical problems remain unsolved. This paper provides an overview of some of what is known about the self-avoiding walk, includ- ing some

Gordon Slade

37

When Human Walking is a Random Walk  

NASA Astrophysics Data System (ADS)

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

Hausdorff, J. M.

1998-03-01

38

Private Mineral Gallery Walk  

NSDL National Science Digital Library

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.

Perkins, Dexter

39

Automata. Walks. Games  

NASA Astrophysics Data System (ADS)

CONTENTS Introduction § 1. Operation of automata in random environments § 2. Walks and the analysis of the behaviour of infinite stochastic automata § 3. Behaviour of finite automata § 4. Games of Markov automata Comments References

Korolyuk, V. S.; Pletnëv, A. I.; Eidel'man, S. D.

1988-02-01

40

Walking beam pumping unit  

SciTech Connect

This patent describes a pumping unit for reciprocating rod-operated well pumps comprising a motor, a crankshaft driven by the motor, a crank having an end driven from the crankshaft, a samson post having a top, a fixed position horizontal shaft at the top of the samson post, a walking beam having a first end and a second end rockable about a horizontal axis, a first shaft at the first end of the walking beam. It is pivotally coupled to the end of the crank. An operating rod is pivotally coupled to the second end of the walking beam. A hangar arm of predetermined length is suspended from the fixed position horizontal shaft for pivotal movement thereabout. A further horizontal shaft is movable through a circular arc by which the hanger arm is pivotally coupled to the walking beam at a point intermediate its ends.

Sable, C.

1987-06-09

41

Proper Noun Gallery Walk  

NSDL National Science Digital Library

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.

World, Education

42

Why not walk faster?  

PubMed

Bipedal walking following inverted pendulum mechanics is constrained by two requirements: sufficient kinetic energy for the vault over midstance and sufficient gravity to provide the centripetal acceleration required for the arc of the body about the stance foot. While the acceleration condition identifies a maximum walking speed at a Froude number of 1, empirical observation indicates favoured walk-run transition speeds at a Froude number around 0.5 for birds, humans and humans under manipulated gravity conditions. In this study, I demonstrate that the risk of 'take-off' is greatest at the extremes of stance. This is because before and after kinetic energy is converted to potential, velocities (and so required centripetal accelerations) are highest, while concurrently the component of gravity acting in line with the leg is least. Limitations to the range of walking velocity and stride angle are explored. At walking speeds approaching a Froude number of 1, take-off is only avoidable with very small steps. With realistic limitations on swing-leg frequency, a novel explanation for the walk-run transition at a Froude number of 0.5 is shown. PMID:17148201

Usherwood, James Richard

2005-09-22

43

D.U.C.K. Walking.  

ERIC Educational Resources Information Center

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…

Steller, Jenifer J.

44

Walking at stability's edge  

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

45

Mechanics of competition walking.  

PubMed Central

1. The work done at each step to lift and accelerate the centre of mass of the body has been measured in competition walkers during locomotion from 2 to 20 km/hr. 2. Three distinct phases characterize the mechanics of walking. From 2 to 6 km/hr the vertical displacement during each step, Sv, increases to a maximum (3.5 vs. 6 cm in normal walking) due to an increase in the amplitude of the rotation over the supporting leg. 3. The transfer, R, between potential energy of vertical displacement and kinetic energy of forward motion during this rotation, reaches a maximum at 4-5 km/hr (R = 65%). From 6 to 10 km/hr R decreases more steeply than in normal walking, indicating a smaller utilization of the pendulum-like mechanism characteristic of walking. 4. Above 10 km/hr potential and kinetic energies vary during each step because both are simultaneously taken up and released by the muscles with almost no transfer between them (R = 2-10%). Above 13-14 km/hr an aerial phase (25-60 msec) takes place during the step. 5. Speeds considerably greater than in normal walking are attained thanks to a greater efficiency of doing positive work. This is made possible by a mechanism of locomotion allowing an important storage and recovery of mechanical energy by the muscles.

Cavagna, G A; Franzetti, P

1981-01-01

46

Mechanics of competition walking.  

PubMed

1. The work done at each step to lift and accelerate the centre of mass of the body has been measured in competition walkers during locomotion from 2 to 20 km/hr. 2. Three distinct phases characterize the mechanics of walking. From 2 to 6 km/hr the vertical displacement during each step, Sv, increases to a maximum (3.5 vs. 6 cm in normal walking) due to an increase in the amplitude of the rotation over the supporting leg. 3. The transfer, R, between potential energy of vertical displacement and kinetic energy of forward motion during this rotation, reaches a maximum at 4-5 km/hr (R = 65%). From 6 to 10 km/hr R decreases more steeply than in normal walking, indicating a smaller utilization of the pendulum-like mechanism characteristic of walking. 4. Above 10 km/hr potential and kinetic energies vary during each step because both are simultaneously taken up and released by the muscles with almost no transfer between them (R = 2-10%). Above 13-14 km/hr an aerial phase (25-60 msec) takes place during the step. 5. Speeds considerably greater than in normal walking are attained thanks to a greater efficiency of doing positive work. This is made possible by a mechanism of locomotion allowing an important storage and recovery of mechanical energy by the muscles. PMID:7310710

Cavagna, G A; Franzetti, P

1981-06-01

47

Walks on SPR neighborhoods.  

PubMed

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

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

48

JungleWalk  

NSDL National Science Digital Library

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.

2002-01-01

49

Relationship Between Arm Movement and Walking Stability in Bipedal Walking.  

National Technical Information Service (NTIS)

Research on bipedal walking is currently underway in a variety of fields. In engineering, robots that can walk in a bipedal manner are now under development, and, in medicine, important data on human walking characteristics are being gathered for use in t...

M. Shibukawa K. Sugitani R. Hong K. Kasamatsu S. Suzuki

2001-01-01

50

Quantum walks with history dependence  

NASA Astrophysics Data System (ADS)

We introduce a multi-coin discrete quantum walk where the amplitude for a coin flip depends upon previous tosses. Although the corresponding classical random walk is unbiased, a bias can be introduced into the quantum walk by varying the history dependence. By mixing the biased walk with an unbiased one, the direction of the bias can be reversed leading to a new quantum version of Parrondo's paradox.

Flitney, A. P.; Abbott, D.; Johnson, N. F.

2004-07-01

51

Compensatory advantages of toe walking  

Microsoft Academic Search

Objectives: The study's hypothesis is that toe walking requires less peak muscle strength distally about the ankle and knee compared with normal heel-toe walking and thus may have compensatory advantages for patients with upper motor neuron injury and distal muscle weakness.Design: Motion analysis and force platform data were collected in able-bodied subjects during toe walking and normal walking. Sagittal plane

D. Casey Kerrigan; Patrick O. Riley; Shannon Rogan; David T. Burke

2000-01-01

52

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.

53

Passive walking with knees  

Microsoft Academic Search

It is shown that passive dynamic walking, a phenomenon originally described for bipeds having straight legs, also works with knees. Thus, giving only a downhill slope as a source of energy, a human-like pair of legs will settle into a natural gait generated by the passive interaction of gravity and inertia. No muscular input is required. The physics is much

T. McGeer

1990-01-01

54

Walking lessons from orangutans  

NSDL National Science Digital Library

A group of scientists in the United Kingdom now have a different idea of how we came to walk on two legs. They got their idea from watching wild orangutans, who spend almost their whole lives in the trees of the rainforest.

American Association for the Advancement of Science (AAAS;)

2007-06-01

55

Take a Planet Walk  

ERIC Educational Resources Information Center

|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…

Schuster, Dwight

2008-01-01

56

Walking in My Shoes  

ERIC Educational Resources Information Center

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

Salia, Hannah

2010-01-01

57

Water-walking devices  

Microsoft Academic Search

We report recent efforts in the design and construction of water-walking machines inspired by insects and spiders. The fundamental\\u000a physical constraints on the size, proportion and dynamics of natural water-walkers are enumerated and used as design criteria\\u000a for analogous mechanical devices. We report devices capable of rowing along the surface, leaping off the surface and climbing\\u000a menisci by deforming the

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

2007-01-01

58

Walk the Plank  

NSDL National Science Digital Library

When one end of a wooden board is placed on a bathroom scale and the other end is suspended on a textbook, students can "walk the plank" and record the weight measurement as their distance from the scale changes. This investigation leads to a real world occurrence of negative slope, examples of which are often hard to find. An activity sheet and full instructions are included.

Zordak, Samuel E.

2000-01-01

59

Towards Smooth Bipedal Walking  

Microsoft Academic Search

In this paper we examine exchange-of-support for a simple planar bipedal robot. We derive a set of conditions which will ensure that the robot's body does not experience an instantaneous change in velocity at exchange-of-support. These conditions specify leg lengths and velocities which the robot must achieve for impactless walking. We propose to smooth the single-support phase through the use

Eric R. Dunn; Robert D. Howe

1994-01-01

60

Can we really walk straight?  

PubMed

Twenty healthy men were asked to walk as straight as possible to a target 60 m away at normal speed. A series of footprints was recorded for each subject by having him wear socks soaked with red ink and walk on white paper fixed flat to the floor. Fourier analysis was applied to determine whether the subjects actually were able to walk straight, and the results revealed that all walked in a sinuous line rather than a straight line. Periodicity and amplitude of the meandering differed from subject to subject. These facts suggest that none of us can walk in a strictly straight line; rather, we meander, primarily due to a slight structural or functional imbalance of our limbs, which produces a gait asymmetry, and secondarily due to feedback from our sense of sight, which acts to correct the shifted walking course. PMID:1530060

Uetake, T

1992-09-01

61

Dynamic Walk of a Biped  

Microsoft Academic Search

The authors have developed five kinds of biped locomotive robots so far. They are named BIPER-1, 2, 3, 4, and 5. All of them are statically unstable but can perform a dynamically stable walk with suitable control. BIPER-1 and BIPER-2 walk only sideways. BIPER-3 is a stilt-type robot whose foot contacts occur at a point and who can walk sideways,

Hirofumi Miura; Isao Shimoyama

1984-01-01

62

BBC: Walking with Beasts  

NSDL National Science Digital Library

This BBC Web site comes loaded with interactive multimedia features on evolution and the animal kingdom. Users can view 3-D images as well as video and audio clips of prehistoric creatures, play an interactive evolution game, and much more. The Web site also includes dozens of comprehensive, downloadable lessons plans and worksheets for students age 7-14 (click on Teachers to access these materials). The lesson plans encourage offline investigation and problem solving, but also provide links to relevant features within the Walking with Beasts Web site. The use of certain online features, with their engaging visuals and interactive design, should make these lesson plans especially appealing to students.

63

BBC: Walking with Beasts  

NSDL National Science Digital Library

This BBC Web site comes loaded with interactive multimedia features on evolution and the animal kingdom. Users can view 3-D images as well as video and audio clips of prehistoric creatures, play an interactive evolution game, and much more. The Web site also includes dozens of comprehensive, downloadable lessons plans and worksheets for students age 7-14 (click on Teachers to access these materials). The lesson plans encourage offline investigation and problem solving, but also provide links to relevant features within the Walking with Beasts Web site. The use of certain online features, with their engaging visuals and interactive design, should make these lesson plans especially appealing to students.

2008-09-04

64

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

SciTech Connect

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

Whitfield, James D.; Rodriguez-Rosario, Cesar A.; Aspuru-Guzik, Alan [Department of Chemistry and Chemical Biology and Center for Excitonics, Harvard University, Cambridge, Massachusetts 02138 (United States)

2010-02-15

65

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

NASA Astrophysics Data System (ADS)

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

Whitfield, James D.; Rodríguez-Rosario, César A.; Aspuru-Guzik, Alán

2010-02-01

66

Biomechanics of walking with snowshoes.  

PubMed

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

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

2012-03-01

67

Walking and Cycling as Transport.  

National Technical Information Service (NTIS)

In this report the possibilities for more people to walk or use a bicycle over short distances is discussed. Comparisons between North European countries show limitations. The bike is mostly used by people without a car, and as an alternative to walking o...

T. Solheim

1997-01-01

68

Analyzing dynamics of arthropod walking  

Microsoft Academic Search

The application of dynamic analysis and design system (DADS) software to dynamics of arthropod walking is discussed. Darkling beetles were used as subjects, a dead beetle for description of leg kinematics and a live beetle to describe motion during walking. Joint torques were determined by using DADS inverse dynamic analysis. The beetle body was assumed to be immobile with its

V. Moyer; E. Fichter; B. Fichter

1988-01-01

69

Endless self-avoiding walks  

NASA Astrophysics Data System (ADS)

We introduce a self-avoiding walk model for which end-effects are completely eliminated. We enumerate the number of these walks for various lattices in dimensions two and three, and use these enumerations to study the properties of this model. We find that endless self-avoiding walks have the same connective constant as self-avoiding walks, and the same Flory exponent ?. However, there is no power law correction to the exponential number growth for this new model, i.e. the critical exponent ? = 1 exactly in any dimension. In addition, the number growth has no analytic corrections to scaling, and we have convincing numerical evidence to support the conjecture that the amplitude for the number growth is a universal quantity. The technique by which end-effects are eliminated may be generalized to other models of polymers such as interacting self-avoiding walks.

Clisby, Nathan

2013-06-01

70

Quantum walks on quotient graphs  

NASA Astrophysics Data System (ADS)

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. 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.

Krovi, Hari; Brun, Todd A.

2007-06-01

71

Walking On Air  

NASA Video Gallery

This video features a series of time lapse sequences photographed by the Expedition 30 crew aboard the International Space Station. Set to the song “Walking in the Air,” by Howard Blake, the video takes viewers around the world, through auroras, and over dazzling lightning displays. The sequences are as follows: :01 – Stars over southern United States :08 – US west coast to Canada :21 – Central Europe to the Middle East :36 – Aurora Australis over the Indian Ocean :54 – Storms over Africa 1:08 – Central United States 1:20 – Midwest United States 1:33 – United Kingdom to Baltic Sea 1:46 – Moonset 1:55 – Northern United States to Eastern Canada 2:12 – Aurora Australis over the Indian Ocean 2:32 – Comet Lovejoy 2:53 – Aurora Borealis over Hudson Bay 3:06 – United Kingdom to Central Europe

Russell Todd D

2012-04-19

72

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

NASA Astrophysics Data System (ADS)

We introduce the quantum stochastic walk (QSW), which determines the evolution of generalized quantum mechanical walk on a graph that obeys a quantum stochastic equation of motion. Using an axiomatic approach, we specify the rules for all possible quantum, classical and quantum-stochastic transitions from a vertex as defined by its connectivity. We show how the family of possible QSWs encompasses both the classical random walk (CRW) and the quantum walk (QW) as special cases, but also includes more general probability distributions. As an example, we study the QSW on a line, the QW to CRW transition and transitions to genearlized QSWs that go beyond the CRW and QW. QSWs provide a new framework to the study of quantum algorithms as well as of quantum walks with environmental effects.

Aspuru-Guzik, Alan

2010-03-01

73

Assessing walking disability in multiple sclerosis.  

PubMed

Most patients with multiple sclerosis (MS) eventually experience walking disability. The objective of this review was to evaluate the clinical utility of measures specific for walking in MS. Walking assessments had high reliability and were correlated with related measures, including the 12-item multiple sclerosis walking scale (MSWS-12). Shorter timed walking tests (Timed 25-foot Walk (T25FW), 10-metre Timed Walk, 30-metre Timed Walk) measure overall walking disability and are best suited for clinical settings, whereas longer timed or distance tests (100-metre Timed Walk, 6-minute Walk Test, 2-minute Walk Test) are better for the assessment of walking fatigability, distance limitations and functional capacity. The MSWS-12 measures different, but related, aspects of walking than the objective tests. The T25FW is the best characterised objective measure of walking disability and can be used across a wide range of walking disabilities. Additional work is needed to fully characterise the other objective walking assessments in MS. PMID:22740603

Kieseier, Bernd C; Pozzilli, Carlo

2012-04-24

74

Constraining walking and custodial technicolor  

SciTech Connect

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

Foadi, Roshan; Frandsen, Mads T.; Sannino, Francesco [University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen (Denmark)

2008-05-01

75

The Effects of Walking Behavior on Mood.  

ERIC Educational Resources Information Center

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

Snodgrass, Sara E.; And Others

76

Families of prudent self-avoiding walks  

Microsoft Academic Search

A self-avoiding walk on the square lattice is prudent, if it never takes a step towards a vertex it has already visited. Préa was the first to address the enumeration of these walks, in 1997. For 4 natural classes of prudent walks, he wrote a system of recurrence relations, involving the length of the walks and some additional \\

Mireille Bousquet-Mélou

2010-01-01

77

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 ...

78

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 ...

79

Rural women walking for health.  

PubMed

The purpose of this qualitative study is to describe rural women's barriers and motivators for participation in a walking program. Twenty rural women, ages 22 to 65, participated in a 12-week walking program. Data from field notes and focus groups were analyzed using qualitative content analysis. Data were inductively coded, codes were categorized into themes, and themes were classified as barriers or motivators to adopting a walking program. Three main barriers are identified: balancing family and self, chronic illness gets in the way of routine, and illness or injury breaks routine. Seven motivators are identified: being part of a group, group camaraderie, learning, pacesetter, seeing progress, energizing, and I am a walker. Women report that family responsibilities are a powerful and pervasive barrier. Motivators center on the importance of group interaction. This qualitative study increases our understanding of rural women's barriers and motivators to embarking on and sustaining a regular walking routine. PMID:17634383

Perry, Cindy K; Rosenfeld, Anne G; Kendall, Judith

2007-07-18

80

Random Walk 2D Model  

NSDL National Science Digital Library

The EJS Random Walk 2D Model simulates a 2-D random walk. You can change the number of walkers and probability of going a given direction. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The Random Walk 2D Model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_RandomWalk2D.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-04-27

81

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 ...

82

Detecting Perturbation Occurrence during Walking  

Microsoft Academic Search

This research aims at the development and verification of a system that can detect the occurrence of perturbation during walking\\u000a for walking-assist as soon as possible by from output signals of an artificial sensor system fitted on users’ body. In this\\u000a research, a back-propagation based artificial neural network (ANN) model was employed to build pattern recognition unit that\\u000a can deal

Yoko Hagane; Wenwei Yu; Ryu Katoh; Tamotu Katane; Masaki Sekine; Toshiyo Tamura; Osami Saitou

83

Technicolor walks at the LHC  

SciTech Connect

We analyze the potential of the Large Hadron Collider (LHC) to observe signatures of phenomenologically viable walking technicolor models. We study and compare the Drell-Yan and vector boson fusion mechanisms for the production of composite heavy vectors. We find that the heavy vectors are most easily produced and detected via the Drell-Yan processes. The composite Higgs phenomenology is also studied. If technicolor walks at the LHC, its footprints will be visible and our analysis will help in uncovering them.

Belyaev, Alexander; Foadi, Roshan; Frandsen, Mads T.; Jaervinen, Matti; Sannino, Francesco; Pukhov, Alexander [NExT Institute: School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom, and Particle Physics Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); High Energy Physics Center, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119992 (Russian Federation)

2009-02-01

84

Random walk models in biology.  

PubMed

Mathematical modelling of the movement of animals, micro-organisms and cells is of great relevance in the fields of biology, ecology and medicine. Movement models can take many different forms, but the most widely used are based on the extensions of simple random walk processes. In this review paper, our aim is twofold: to introduce the mathematics behind random walks in a straightforward manner and to explain how such models can be used to aid our understanding of biological processes. We introduce the mathematical theory behind the simple random walk and explain how this relates to Brownian motion and diffusive processes in general. We demonstrate how these simple models can be extended to include drift and waiting times or be used to calculate first passage times. We discuss biased random walks and show how hyperbolic models can be used to generate correlated random walks. We cover two main applications of the random walk model. Firstly, we review models and results relating to the movement, dispersal and population redistribution of animals and micro-organisms. This includes direct calculation of mean squared displacement, mean dispersal distance, tortuosity measures, as well as possible limitations of these model approaches. Secondly, oriented movement and chemotaxis models are reviewed. General hyperbolic models based on the linear transport equation are introduced and we show how a reinforced random walk can be used to model movement where the individual changes its environment. We discuss the applications of these models in the context of cell migration leading to blood vessel growth (angiogenesis). Finally, we discuss how the various random walk models and approaches are related and the connections that underpin many of the key processes involved. PMID:18426776

Codling, Edward A; Plank, Michael J; Benhamou, Simon

2008-08-01

85

Portable walking beam pump jack  

SciTech Connect

This patent describes a portable walking beam pump jack for use in pumping liquids from an oil well. This jack consists of: an elongated frame having a longitudinal axis and front and rear ends, the frame also including first and second support seats; a towing receptacle, an axle connected transversely across the frame; ground engaging wheels connected to the axle for supporting the frame for rolling transportation; stabilizing means for securing the frame with respect to a ground location; a walking beam having a first end, a midportion and a second end, the second end being adapted for connection to a pumping rod; an engine mounted on the frame; a pair of arms counterweighted for balancing a pumping rod connected to the walking beam, a drive yoke, a support assembly foldably mounted on the frame and upon which the midportion of the walking beam is pivotally connected, the support assembly the arms and the drive yoke being foldable together, from a first, fixed position in which the walking beam arms and yoke are supported in a raised position for rocking in a pumping motion to a second, fixed position disposed downwardly and forwardly from the first fixed position and in which the walking beam arms and yoke are held in a lowered position for transportation; a front support and a hydraulic cylinder connected between the frame and the support assembly for moving the support assembly between the first, fixed position and the second fixed position.

Laney, R.N.

1986-02-25

86

Progressive locomotor recalibration during blind walking  

PubMed Central

Blind walking has become a common measure of perceived target location. This article addresses the possibility that blind walking might vary systematically within an experimental session as participants accrue exposure to nonvisual locomotion. Such variations could complicate the interpretation of blind walking as a measure of perceived location. We measured walked distance, velocity, and pace length in indoor and outdoor environments (1.5–16.0 m target distances). Walked distance increased over 37 trials by approximately 9.33% of the target distance; velocity (and to a lesser extent, pace length) also increased, primarily in the first few trials. In addition, participants exhibited more unintentional forward drift in a blindfolded marching-in-place task after exposure to nonvisual walking. The results suggest that participants not only gain confidence as blind-walking exposure increases, but also adapt to nonvisual walking in a way that biases responses toward progressively longer walked distances.

Philbeck, John W.; Woods, Adam J.; Arthur, Joeanna; Todd, Jennifer

2010-01-01

87

Noisy continuous time random walks.  

PubMed

Experimental studies of the diffusion of biomolecules within biological cells are routinely confronted with multiple sources of stochasticity, whose identification renders the detailed data analysis of single molecule trajectories quite intricate. Here, we consider subdiffusive continuous time random walks that represent a seminal model for the anomalous diffusion of tracer particles in complex environments. This motion is characterized by multiple trapping events with infinite mean sojourn time. In real physical situations, however, instead of the full immobilization predicted by the continuous time random walk model, the motion of the tracer particle shows additional jiggling, for instance, due to thermal agitation of the environment. We here present and analyze in detail an extension of the continuous time random walk model. Superimposing the multiple trapping behavior with additive Gaussian noise of variable strength, we demonstrate that the resulting process exhibits a rich variety of apparent dynamic regimes. In particular, such noisy continuous time random walks may appear ergodic, while the bare continuous time random walk exhibits weak ergodicity breaking. Detailed knowledge of this behavior will be useful for the truthful physical analysis of experimentally observed subdiffusion. PMID:24089728

Jeon, Jae-Hyung; Barkai, Eli; Metzler, Ralf

2013-09-28

88

Noisy continuous time random walks  

NASA Astrophysics Data System (ADS)

Experimental studies of the diffusion of biomolecules within biological cells are routinely confronted with multiple sources of stochasticity, whose identification renders the detailed data analysis of single molecule trajectories quite intricate. Here, we consider subdiffusive continuous time random walks that represent a seminal model for the anomalous diffusion of tracer particles in complex environments. This motion is characterized by multiple trapping events with infinite mean sojourn time. In real physical situations, however, instead of the full immobilization predicted by the continuous time random walk model, the motion of the tracer particle shows additional jiggling, for instance, due to thermal agitation of the environment. We here present and analyze in detail an extension of the continuous time random walk model. Superimposing the multiple trapping behavior with additive Gaussian noise of variable strength, we demonstrate that the resulting process exhibits a rich variety of apparent dynamic regimes. In particular, such noisy continuous time random walks may appear ergodic, while the bare continuous time random walk exhibits weak ergodicity breaking. Detailed knowledge of this behavior will be useful for the truthful physical analysis of experimentally observed subdiffusion.

Jeon, Jae-Hyung; Barkai, Eli; Metzler, Ralf

2013-09-01

89

Walking the history of healthcare.  

PubMed

The history of healthcare is complex, confusing and contested. In Walking London's medical history the story of how health services developed from medieval times to the present day is told through seven walks. The book also aims to help preserve our legacy, as increasingly former healthcare buildings are converted to other uses, and to enhance understanding of the current challenges we face in trying to improve healthcare in the 21st century. Each walk has a theme, ranging from the way hospitals merge or move and the development of primary care to how key healthcare trades became professions and the competition between the church, Crown and City for control of healthcare. While recognising the contributions of the 'great men of medicine', the book takes as much interest in the six ambulance stations built by the London County Council (1915) as the grandest teaching hospitals. PMID:18193703

Black, Nick

2007-12-01

90

Base Station Walk-Back  

NSDL National Science Digital Library

In this activity, learners will train to improve lung, heart, and other muscle endurance as they walk a progressive, measured distance. Learners measure out a course according to specific distances, walk/jog/run the distance, and record and graph their observations. This activity simulates how astronauts must train before missions in order to build up the endurance required to move in space. An embedded video on this page showcases the activity. Learners can complete this activity as part of NASA's Fit Explorer Challenge, in which learners train like astronauts, set goals, track their progress, and accumulate points to progress through Exploration Levels and earn certificates.

Center, Nasa J.

2012-06-26

91

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

Microsoft Academic Search

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

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

2000-01-01

92

After Talking the Talk, Now Walk the Walk  

ERIC Educational Resources Information Center

|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…

Vukovic, Paul

2011-01-01

93

Quantum walks, quantum gates, and quantum computers  

SciTech Connect

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 single-excitation and multiexcitation encodings. 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.

Hines, Andrew P. [Pacific Institute of Theoretical Physics and Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, V6T 1Z1 (Canada); Pacific Institute for the Mathematical Sciences, 1933 West Mall, University of British Columbia, Vancouver, British Columbia, V6T 1Z2 (Canada); Stamp, P. C. E. [Pacific Institute of Theoretical Physics and Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, V6T 1Z1 (Canada)

2007-06-15

94

Tracking Human Walking Using MARG Sensors.  

National Technical Information Service (NTIS)

This thesis addresses modeling and simulation of the human lower extremities in order to track walking motion and estimate walking distance. The lower extremities are modeled as an articulated object, which consists of rigid bars connected to each other b...

I. Pantazis

2005-01-01

95

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

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Definitions concerning walk-in coolers and walk-in freezers. 431.302 Section 431.302 Energy...PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers §...

2010-01-01

96

Walking practice and suburban nature-talk  

Microsoft Academic Search

Drawing on recent conceptualisations of ‘performativity’ this article examines the experiential knowledge of a heterogenous group of people who regularly walk through a maze of criss-crossing paths in a relatively flat suburban Australian reserve. Attention is given to how routine walking can be conceptualised as one way of ‘doing’ nature. Routine walking is conceptualised as a territory-making process. Mindful of

Gordon Waitt; Nicholas Gill; Lesley Head

2009-01-01

97

Walking and Rhythmicity: Sensing Urban Space  

Microsoft Academic Search

As an inescapable part of our everyday lifeworld, walking is an embodied practice with specific lived qualities. It is also a mode of experiencing place and the city, and in this context is an aesthetic and insightful spatial practice. Through everyday walking we develop a sense of (and for) place. The everyday practices of walking vary in their purpose, pace

FILIPA MATOS WUNDERLICH

2008-01-01

98

Developmental Continuity? Crawling, Cruising, and Walking  

ERIC Educational Resources Information Center

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…

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

2011-01-01

99

Idiopathic toe walking and sensory processing dysfunction  

Microsoft Academic Search

BACKGROUND: It is generally understood that toe walking involves the absence or limitation of heel strike in the contact phase of the gait cycle. Toe walking has been identified as a symptom of disease processes, trauma and\\/or neurogenic influences. When there is no obvious cause of the gait pattern, a diagnosis of idiopathic toe walking (ITW) is made. Although there

Cylie M Williams; Paul Tinley; Michael Curtin

2010-01-01

100

Sustaining place through community walking initiatives  

Microsoft Academic Search

Purpose – The purpose of this paper is to summarise findings from collaborative research with Sheffield City Council to help contribute to a national healthy walks initiative. The primary purpose of the initiative is to help encourage a more active lifestyle through the uptake of regular walking. Highlighted here are some of the Sheffield urban walks which aimed to engage

Stephen Dobson

2011-01-01

101

Humanoid robot walking control on inclined planes  

Microsoft Academic Search

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

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

2011-01-01

102

Behavior Management by Walking Around  

ERIC Educational Resources Information Center

|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…

Boardman, Randolph M.

2004-01-01

103

Walk around the Block Curriculum.  

ERIC Educational Resources Information Center

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

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

104

A Walk to the Well.  

ERIC Educational Resources Information Center

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

Weir, Phil

1994-01-01

105

Walking, and Learning, with Rosie.  

ERIC Educational Resources Information Center

This brief article describes a children's story, "Rosie's Walk," which has been made fully accessible for deaf children in CD-ROM through inclusion of more than 120 sign language sequences (American Sign Language and Signed English), as well as voice and written text. The disk also includes six educational games. (DB)

Kurlychek, Ken

1996-01-01

106

Science Sampler: Walking Out Graphs  

NSDL National Science Digital Library

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).

Shen, Ji

2009-12-01

107

Listening Walks and Singing Maps  

ERIC Educational Resources Information Center

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

Cardany, Audrey Berger

2011-01-01

108

A Leadership Walk across Gettysburg  

ERIC Educational Resources Information Center

|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…

Millward, Robert E.

2009-01-01

109

A Walk to the Well.  

ERIC Educational Resources Information Center

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

Weir, Phil

1994-01-01

110

The Recovery of Walking in Stroke Patients: A Review  

ERIC Educational Resources Information Center

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

Jang, Sung Ho

2010-01-01

111

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

ERIC Educational Resources Information Center

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

Alfonzo, Mariela

2005-01-01

112

Average trajectory of returning walks.  

PubMed

We compute the average shape of trajectories of some one-dimensional stochastic processes x(t) in the (t,x) plane during an excursion, i.e., between two successive returns to a reference value, finding that it obeys a scaling form. For uncorrelated random walks the average shape is semicircular, independent from the single increments distribution, as long as it is symmetric. Such universality extends to biased random walks and Levy flights, with the exception of a particular class of biased Levy flights. Adding a linear damping term destroys scaling and leads asymptotically to flat excursions. The introduction of short and long ranged noise correlations induces nontrivial asymmetric shapes, which are studied numerically. PMID:15169006

Colaiori, Francesca; Baldassarri, Andrea; Castellano, Claudio

2004-04-30

113

Quantum walks with infinite hitting times  

NASA Astrophysics Data System (ADS)

Hitting times are the average time it takes a walk to reach a given final vertex from a given starting vertex. The hitting time for a classical random walk on a connected graph will always be finite. We show that, by contrast, 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, which for discrete time quantum walks is that the degeneracy of the evolution operator be greater than the degree of the graph. The set of initial states which give an infinite hitting time form a subspace. The phenomenon of infinite hitting times is in general a consequence of the symmetry of the graph and its automorphism group. 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. In the case of the discrete walk, if this condition is satisfied the walk will have infinite hitting times for any choice of a coin operator, and we give a class of graphs with infinite hitting times for any choice of coin. Hitting times are not very well defined for continuous time quantum walks, but we show that the idea of infinite hitting-time walks naturally extends to the continuous time case as well.

Krovi, Hari; Brun, Todd A.

2006-10-01

114

Quantum walks with infinite hitting times  

SciTech Connect

Hitting times are the average time it takes a walk to reach a given final vertex from a given starting vertex. The hitting time for a classical random walk on a connected graph will always be finite. We show that, by contrast, 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, which for discrete time quantum walks is that the degeneracy of the evolution operator be greater than the degree of the graph. The set of initial states which give an infinite hitting time form a subspace. The phenomenon of infinite hitting times is in general a consequence of the symmetry of the graph and its automorphism group. 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. In the case of the discrete walk, if this condition is satisfied the walk will have infinite hitting times for any choice of a coin operator, and we give a class of graphs with infinite hitting times for any choice of coin. Hitting times are not very well defined for continuous time quantum walks, but we show that the idea of infinite hitting-time walks naturally extends to the continuous time case as well.

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

2006-10-15

115

Walking Capacity of Bariatric Surgery Candidates  

PubMed Central

Background This study characterizes the walking limitations of bariatric surgery candidates by age and body mass index (BMI) and determines factors independently associated with walking capacity. Setting Multi-institutional at research university hospitals in the United States. Methods 2458 participants of the Longitudinal Assessment of Bariatric Surgery study (age: 18-78 y, BMI: 33-94 kg/m2) attended a pre-operative research visit. Walking capacity was measured via self-report and the 400 meter Long Distance Corridor Walk (LDCW). Results Almost two-thirds (64%) of subjects reported limitations walking several blocks, 48% had an objectively-defined mobility deficit, and 16% reported at least some walking aid use. In multivariable analysis, BMI, older age, lower income and greater bodily pain were independently associated (p<.05) with walking aid use, physical discomfort during the LDCW, inability to complete the LDCW, and slower time to complete the LDCW. Female sex, Hispanic ethnicity (but not race), higher resting heart rate, history of smoking, several comoribidities (history of stroke, ischemic heart disease, diabetes, asthma, sleep apnea, venous edema with ulcerations), and depressive symptoms were also independently related (p<.05) to at least one measure of reduced walking capacity. Conclusions Walking limitations are common in bariatric surgery candidates, even among the least severely obese and youngest patients. Physical activity counseling must be tailored to individuals' abilities. While several factors identified in this study (e.g., BMI, age, pain, comorbidities) should be considered, directly assessing walking capacity will facilitate appropriate goal-setting.

King, WC; Engel, SG; Elder, KA; Chapman, WH; Eid, GM; Wolfe, BM; Belle, SH

2011-01-01

116

Walk-Startup of a Two-Legged Walking Mechanism  

NASA Astrophysics Data System (ADS)

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

Babkovi?, Kalman; Nagy, László; Krklješ, Damir; Borovac, Branislav

117

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

Code of Federal Regulations, 2013 CFR

...walk-in coolers and walk-in freezers. Basic model means all components of a given type of...products designed and marketed exclusively for medical, scientific, or research purposes. [74 FR 12074, Mar. 23, 2009,...

2013-01-01

118

On random walks for Pollard's rho method  

Microsoft Academic Search

Abstract. We consider Pollard’s rho method,for discrete logarithm computation. Usually, in the analysis of its running time the assumption is made that a random,walk in the underlying group is simulated. We show that this assumption does not hold for the walk originally suggested by Pollard: its performance is worse than in the random,case. We study alternative walks that can be

Edlyn Teske

2001-01-01

119

Walking gauge dynamics and realistic technicolor  

SciTech Connect

A realistic technicolor model, effective below 150 TeV is outlined. The new feature of the model is that the third generation quarks are unified with the technifermions into multiplets of a walking gauge force down to a scale of [similar to]10 TeV. Because they directly feel the walking force these quarks can have mass enhancements even greater than those of conventional walking schemes. Electroweak radiative corrections are estimable and within experimental limits.

Sundrum, R. (Theoretical Physics Group, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley 94720 (United States) Department of Physics, University of California, Berkeley 94720 (United States))

1992-02-05

120

Machines that walk: The adaptive suspension vehicle  

Microsoft Academic Search

The design and operation of statically stable fully terrain-adaptive walking machines are discussed, with an emphasis on the adaptive-suspension vehicle developed at Ohio State University (Waldron and McGhee, 1986). Chapters are devoted to a review of walking-machine development, gait analysis and gaits for level walking, gaits for irregular terrain, coordination, leg design by four-bar linkage synthesis, design of a pantograph

Shin-Min Song; Kenneth J. Waldron

1989-01-01

121

What Changes in Infant Walking and Why  

Microsoft Academic Search

This study compared the relative contributions of growing body dimensions, age, and walking experience in the development of walking skill in 9- to 17-month-old infants (N 5 210), 5-6-year old kindergartners (N 5 15), and college students (N 5 13). Kinematic measures derived from participants' footprints showed characteristic improvements in walking skill. As children became bigger, older, and more experienced,

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

2003-01-01

122

Estimation of speed and incline of walking using neural network  

Microsoft Academic Search

A portable datalogger is designed to record body accelerations during human walking. The recorded signals are parametrised and the pattern of walking at each gait cycle is found. These patterns are presented to two neural networks which estimate the incline and the speed of walking. Subjects performed a treadmill walking followed by a self paced walking on an outdoor test

K. Aminian; Ph. Robert; E. Jequier; Y. Schutz

1994-01-01

123

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

NASA Astrophysics Data System (ADS)

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.

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

124

Cell phones change the way we walk.  

PubMed

Cell phone use among pedestrians leads to increased cognitive distraction, reduced situation awareness and increases in unsafe behavior. Performing a dual-task, such as talking or texting with a cell phone while walking, may interfere with working memory and result in walking errors. At baseline, thirty-three participants visually located a target 8m ahead; then vision was occluded and they were instructed to walk to the remembered target. One week later participants were assigned to either walk, walk while talking on a cell phone, or walk while texting on a cell phone toward the target with vision occluded. Duration and final location of the heel were noted. Linear distance traveled, lateral angular deviation from the start line, and gait velocity were derived. Changes from baseline to testing were analyzed with paired t-tests. Participants engaged in cell phone use presented with significant reductions in gait velocity (texting: 33% reduction, p=0.01; talking: 16% reduction, p=0.02). Moreover, participants who were texting while walking demonstrated a 61% increase in lateral deviation (p=0.04) and 13% increase in linear distance traveled (p=0.03). These results suggest that the dual-task of walking while using a cell phone impacts executive function and working memory and influences gait to such a degree that it may compromise safety. Importantly, comparison of the two cell phone conditions demonstrates texting creates a significantly greater interference effect on walking than talking on a cell phone. PMID:22226937

Lamberg, Eric M; Muratori, Lisa M

2012-01-05

125

Motor modules in robot-aided walking  

PubMed Central

Background It is hypothesized that locomotion is achieved by means of rhythm generating networks (central pattern generators) and muscle activation generating networks. This modular organization can be partly identified from the analysis of the muscular activity by means of factorization algorithms. The activity of rhythm generating networks is described by activation signals whilst the muscle intervention generating network is represented by motor modules (muscle synergies). In this study, we extend the analysis of modular organization of walking to the case of robot-aided locomotion, at varying speed and body weight support level. Methods Non Negative Matrix Factorization was applied on surface electromyographic signals of 8 lower limb muscles of healthy subjects walking in gait robotic trainer at different walking velocities (1 to 3km/h) and levels of body weight support (0 to 30%). Results The muscular activity of volunteers could be described by low dimensionality (4 modules), as for overground walking. Moreover, the activation signals during robot-aided walking were bursts of activation timed at specific phases of the gait cycle, underlying an impulsive controller, as also observed in overground walking. This modular organization was consistent across the investigated speeds, body weight support level, and subjects. Conclusions These results indicate that walking in a Lokomat robotic trainer is achieved by similar motor modules and activation signals as overground walking and thus supports the use of robotic training for re-establishing natural walking patterns.

2012-01-01

126

Synthesizing New Walk and Climb Motions from a Single Motion Captured Walk Sequence  

Microsoft Academic Search

We describe a method to dynamically synthesize believable variable stride and variable foot lift walk and climb mo- tions from a single motion captured walk sequence. Our method is driven by motion capture and guided by a simple kinematic walk model . The method allows control in the form of stride and lift parameters. It generates a range of variations

Shrinath Shanbhag; Sharat Chandran; CDAC Mumbai

127

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

PubMed

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

Yang, Shuozhi; Li, Qingguo

2011-05-24

128

The effect of walking aids on muscle activation patterns during walking in stroke patients  

Microsoft Academic Search

The purpose of this study was to investigate changes in muscle activation patterns with respect to timing and amplitude that occur when subjects with stroke walk with and without a walking aid. This knowledge could help therapists in deciding whether or not patients should use a cane or quad stick while walking.Thirteen patients suffering from a first unilateral ischemic stroke

J. H. Buurke; H. J. Hermens; C. V. Erren-Wolters; A. V. Nene

2005-01-01

129

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

Microsoft Academic Search

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.

Raymond De Young

130

Random walk in a quasicontinuum  

SciTech Connect

A continuous-time random walk on a spatial lattice described by the Kramers-Moyal expansion has a continuum limit described by a Fokker-Planck equation. It is often desirable to know corrections to quantities computed in the continuum limit, but truncation of the Kramers-Moyal expansion at any level other than the Fokker-Planck either breaks down or yields unphysical results. Here we introduce an alternative approximation to the Kramers-Moyal expansion which circumvents the problems of a naive truncation and correctly incorporates the first-order corrections due to the discrete lattice.

Doering, C.R.; Hagan, P.S.; Rosenau, P.

1987-07-15

131

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

Federal Register 2010, 2011, 2012, 2013

...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...

2011-04-15

132

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

PubMed Central

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

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

2013-01-01

133

Walking activities and wear of prostheses.  

PubMed Central

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

Seedhom, B B; Wallbridge, N C

1985-01-01

134

Improved Guided Random Walk Algorithm for Quantum Field Theory Computations.  

National Technical Information Service (NTIS)

The authors introduce an improved guided random walk algorithm for evaluating vacuum matrix elements in Hamiltonian field theories. The algorithm does not require the creation or absorption of walks, unlike related random walk techniques which have appear...

T. Barnes G. J. Daniell D. Storey

1985-01-01

135

Lévy walks with velocity fluctuations  

NASA Astrophysics Data System (ADS)

The standard Lévy walk is performed by a particle that moves ballistically between randomly occurring collisions when the intercollision time is a random variable governed by a power-law distribution. During instantaneous collision events, the particle randomly changes the direction of motion but maintains the same constant speed. We generalize the standard model to incorporate velocity fluctuations into the process. Two types of models are considered, namely (i) with a walker changing the direction and absolute value of its velocity during collisions only, and (ii) with a walker whose velocity continuously fluctuates. We present a full analytic evaluation of both models and emphasize the importance of initial conditions. We show that, in the limit of weak velocity fluctuations, the integral diffusion characteristics and the bulk of diffusion profiles are identical to those for the standard Lévy walk. However, the type of underlying velocity fluctuations can be identified by looking at the ballistic regions of the diffusion profiles. Our analytical results are corroborated by numerical simulations.

Denisov, S.; Zaburdaev, V.; Hänggi, P.

2012-03-01

136

Interface Reconstruction with Directional Walking  

SciTech Connect

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

Yao, J

2009-05-22

137

What Changes in Infant Walking and Why.  

ERIC Educational Resources Information Center

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…

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

2003-01-01

138

Walking economy in people with Parkinson's disease  

PubMed Central

Gait dysfunction is an early problem identified by patients with Parkinson's disease (PD). Alterations in gait may result in an increase in the energy cost of walking (i.e., walking economy). The purpose of this study was to determine whether walking economy is atypical in patients with PD when compared with healthy controls. A secondary purpose was to evaluate the associations of age, sex, and level of disease severity with walking economy in patients with PD. The rate of oxygen consumption (VO2) and other responses to treadmill walking were compared in 90 patients (64.4±10.3 yr) and 44 controls (64.6±7.3 yr) at several walking speeds. Pearson correlation coefficients (r) were calculated to determine relationships of age, sex, and disease state with walking economy in PD patients. Walking economy was significantly worse in PD patients than in controls at all speeds above 1.0 mph. Across all speeds, VO2 was 6 to 10% higher in PD patients. Heart rate, minute ventilation, respiratory exchange ratio, and rating of perceived exertion were correspondingly elevated. No significant relationship of age, sex, or UPDRS score with VO2 was found for patients with PD. The findings suggest that the physiologic stress of daily physical activities is increased in patients with early to mid-stage PD, and this may contribute to the elevated level of fatigue that is characteristic of PD.

Christiansen, Cory L; Schenkman, Margaret L; McFann, Kim; Wolfe, Pamela; Kohrt, Wendy M

2009-01-01

139

Passively walking five-link robot  

Microsoft Academic Search

In this article we investigate the dynamics of a five-link, passive bipedal robot. The passivity in this context stands for the ability of the robot to walk autonomously down an inclined surface without any external source of energy. Previous research efforts in passive walking were limited to four link models with knees or 2-link models without knees with a variety

Elena Borzova; Yildirim Hurmuzlu

2004-01-01

140

Brownian Optimal Stopping and Random Walks  

SciTech Connect

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.

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

141

Web-Based Walk-Throughs  

ERIC Educational Resources Information Center

|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…

Granada, Janet; Vriesenga, Michael

2008-01-01

142

Walking and the Relationship to Public Transport  

Microsoft Academic Search

This paper is discussing the relationship between public transport and walking. One of the issues, which will be discussed, is whether walking is an alternative to public transport or complements the use of public transport and whether this is different between cities which are dominated by light rail in contrast to buses. According to the research carried out by ETP

Carmen Hass-Klau

143

Electrification of human body by walking  

Microsoft Academic Search

The process of electrification of the human body by walking on resistive floors has been analysed and the corresponding body potential measured. A model for electric body potential caused by walking has been proposed and then verified experimentally. The model combines two main processes: an exponential increase of potential due to successive charging and potential oscillations caused by periodic changes

T. Ficker

2006-01-01

144

Planar bipedal walking with foot rotation  

Microsoft Academic Search

This paper addresses the key problem of walking with both fully-actuated and underactuated phases. The studied robot is planar, bipedal, and fully actuated in the sense that it has feet with revolute, actuated ankles. The desired walking motion is assumed to consist of three successive phases: a fully-actuated phase where the stance foot is flat on the ground, an underactuated

Jun Ho Choi; J. W. Grizzle

2005-01-01

145

Non-Markovian decoherent quantum walks  

NASA Astrophysics Data System (ADS)

Quantum walks act in obviously different ways from their classical counterparts, but decoherence will lessen and close this gap between them. To understand this process, it is necessary to investigate the evolution of quantum walks under different decoherence situations. In this article, we study a non-Markovian decoherent quantum walk on a line. In a short time regime, the behavior of the walk deviates from both ideal quantum walks and classical random walks. The position variance as a measure of the quantum walk collapses and revives for a short time, and tends to have a linear relation with time. That is, the walker's behavior shows a diffusive spread over a long time limit, which is caused by non-Markovian dephasing affecting the quantum correlations between the quantum walker and his coin. We also study both quantum discord and measurement-induced disturbance as measures of the quantum correlations, and observe both collapse and revival in the short time regime, and the tendency to be zero in the long time limit. Therefore, quantum walks with non-Markovian decoherence tend to have diffusive spreading behavior over long time limits, while in the short time regime they oscillate between ballistic and diffusive spreading behavior, and the quantum correlation collapses and revives due to the memory effect.

Xue, Peng; Zhang, Yong-Sheng

2013-07-01

146

Probabilistic information structure of human walking.  

PubMed

Recently, the area of healthcare has been tremendously benefited from the advent of high performance computing in improving quality of life. Different processing techniques have been developed to understand the hidden complexity of the time series and will help clinicians in diagnosis and treatment. Analysis of human walking helps to study the various pathological conditions affecting balance and the elderly. In an elderly subjects, falls and paralysis are major problems, in terms of both frequency and consequences. Correct postural balance is important to well being and its effects will be felt in every movement and activity. In this paper, Bayesian Network (BN) was applied to recorded muscle activities and joint motions during walking, to extract causal information structure of normal walking and different impaired walking. The aim of this study is to use different BNs to express normal walking and various impaired walking, and identify the most important causal pairs that characterize specific impaired walking, through comparing the BNs for different walking. PMID:20703685

Nergui, Myagmarbayar; Murai, Chieko; Koike, Yuka; Yu, Wenwei; Acharya U, Rajendra

2010-07-06

147

Effect of encouragement on walking test performance  

Microsoft Academic Search

Walking tests, frequently used to document effects of treatment on exercise capacity, have never been standardised. We studied the effects of encouragement on walking test performance in a randomised study that controlled for the nature of the underlying disease, time of day, and order effects. We randomised 43 patients with chronic airflow limitation or chronic heart failure or both to

G H Guyatt; S O Pugsley; M J Sullivan; P J Thompson; L Berman; N L Jones; E L Fallen; D W Taylor

1984-01-01

148

Random Walks on Graphs: A Survey  

Microsoft Academic Search

Various aspects of the theory of random walks on graphs are surveyed. In particular, estimates on the important parameters of access time, commute time, cover time and mixing time are discussed. Connections with the eigenvalues of graphs and with electrical networks, and the use of these connections in the study of random walks is described. We also sketch recent algorithmic

L. LOV

1996-01-01

149

Power Demand for Walking on the Treadmill  

NSDL National Science Digital Library

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

Hageseth, Gaylord T.

2000-02-01

150

CONTROL OF STABILITY DURING SLOPE LATERAL WALKING  

Microsoft Academic Search

Objectives: The purpose of this study was to investigate the centre of pressure (COP) trajectory in level and slope lateral walking. Hopefully the results will provide useful information on improving labors' working safety. Method: Five normal subjects participated in this study. The entire lateral walking cycle can be divided into two double support phases and two single support phases (right

Chien-Ju Lin; Lin-Hwa Wang; Yi-Wen Chang; Fong-Chin Su

151

Multilinear decomposition of human walking paths  

Microsoft Academic Search

In a previous work, the authors have shown how the Principal Components Analysis (PCA) of a set of human walking paths provides sufficient information to derive a linear human-like path generator based on examples. The present work aims to provide an analysis of human walking paths from the perspective of multilinear algebra, using the n-mode Singular Value Decomposition (SVD). This

Christian A. Ramirez; M. Castela?n; G. Arechavaleta

2010-01-01

152

SLIP PREVENTION IN WALKING - LOWER EXTREMITY BIOMECHANICS  

Microsoft Academic Search

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

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

153

Posture Control of 6Leg Walking Robot  

Microsoft Academic Search

This paper describes a walking method and inclination control experiments of the new omni-directional walking robot, which has six legs and can move in any direction. The mechanism consists of a parallel link mechanism connecting the two frames with three linear actuators. Legs are attached to each frame. The relative position and angle of the two frames are selected arbitrarily

Toshio Fukuda; Yuji Adachi; Haruo Hoshino; Kazuhiro Kosuge; Isao Matsunaga; Fumihito Arai

1995-01-01

154

Leg Asymmetries and Coordination Dynamics in Walking  

Microsoft Academic Search

Models of interlimb coordination (H. Haken, J. A. S. Kelso, & H. Bunz, 1985; P. N. Kugler & M. T. Turvey, 1987) were tested in walking by examining the role of asymmetries between limbs. Participants walked on a treadmill with and without a metronome. Five asymmetry conditions were created via ankle loads of 0, 3, or 6 kg on either

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

2010-01-01

155

Local Random Walk with Distance Measure  

NASA Astrophysics Data System (ADS)

Link prediction based on random walks has been widely used. The existing random walk algorithms ignore the probability of a walker visit from the initial node to the destination node for the first time, which makes a major contribution to establish links in some networks. To deal with the problem, we develop a link prediction method named Local Random Walk with Distance (LRWD) based on local random walk and the shortest distance of node pairs. In LRWD, walkers walk with their own steps rather than uniform steps. To evaluate the performance of the LRWD algorithm, we present the concept of distance distribution. The experimental results show that LRWD can improve the prediction accuracy when the distance distribution of the network is relatively concentrated.

Xu, Baomin; Xin, Tinglin; Wang, Yunfeng; Zhao, Yanpin

2013-03-01

156

Go Naked: Diapers Affect Infant Walking  

PubMed Central

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 on-going biomechanical perturbation while learning to walk. Furthermore, shifts in diapering practices may have contributed to historical and cross-cultural differences in infant walking.

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

2013-01-01

157

What changes in infant walking and why.  

PubMed

This study compared the relative contributions of growing body dimensions, age, and walking experience in the development of walking skill in 9- to 17-month-old infants (N = 210), 5-6-year old kindergartners (N = 15), and college students (N = 13). Kinematic measures derived from participants' footprints showed characteristic improvements in walking skill. As children became bigger, older, and more experienced, their steps became longer, narrower, straighter, and more consistent. Improvements reflected a narrowing base of support and increasing control over the path of progression. Although both infants' age and the duration of their walking experience contributed to improvements in walking skill, experience was the stronger predictor. This finding suggests that practice is the more important developmental factor for helping infants to conquer their weak muscles and precarious balance. PMID:12705568

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

158

Go naked: diapers affect infant walking.  

PubMed

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

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

2012-09-07

159

Hitting time for the continuous quantum walk  

NASA Astrophysics Data System (ADS)

We define the hitting (or absorbing) time for the case of continuous quantum walks by measuring the walk at random times, according to a Poisson process with measurement rate ? . From this definition we derive an explicit formula for the hitting time, and explore its dependence on the measurement rate. As the measurement rate goes to either 0 or infinity the hitting time diverges; the first divergence reflects the weakness of the measurement, while the second limit results from the quantum zeno effect. Continuous-time quantum walks, like discrete-time quantum walks but unlike classical random walks, can have infinite hitting times. We present several conditions for existence of infinite hitting times, and discuss the connection between infinite hitting times and graph symmetry.

Varbanov, Martin; Krovi, Hari; Brun, Todd A.

2008-08-01

160

Physiological responses to nordic walking, walking and jogging.  

PubMed

The goal of this study was to evaluate the physiological responses during incremental field tests (FT) in nordic walking (NW), walking (W) and jogging (J). Fifteen healthy middle-aged women participated in three FT. Heart rate (HR) and oxygen uptake (V(O)(2)) were monitored continuously by portable analyzers. Capillary blood lactate (La) was analyzed at rest and after every stage of the FT. The disciplines showed differences during stage 1.8 and 2.1 m s(-1) for V(O)(2) between NW and W (P < 0.05). The maximum value was measured at 1.8 m s(-1 )(8%). In accordance with La, V(CO)(2) was higher in NW compared with W during all stages (P < 0.05) and even higher in NW compared with J during 2.1 and 2.4 m s(-1). While there were higher HR for NW and W at 2.4 m s(-1) than in J (P < 0.01), there were increases for HR at fixed values of 2 (La2) and 4 (La4) mmol l(-1 )lactate for J compared with NW and W (P < 0.01). Although the speed of NW was slower than that of W at La2 and La4 (P < 0.05), there were no differences for the HR and the V(O)(2) Our results demonstrate that metabolic responses are a helpful instrument to assess the intensity during bipedal exercise. As NW speed at submaximal lactate levels is lower than in W and J, W and J test measures of HR and V(O)(2) are not suitable for NW training recommendations. Additionally, the V(O)(2) formed by performing NW is not as high as previously reported. PMID:16799817

Schiffer, Thorsten; Knicker, Axel; Hoffman, Uwe; Harwig, Brigitte; Hollmann, Wildor; Strüder, Heiko K

2006-06-24

161

Common muscle synergies for balance and walking  

PubMed Central

Little is known about the integration of neural mechanisms for balance and locomotion. Muscle synergies have been studied independently in standing balance and walking, but not compared. Here, we hypothesized that reactive balance and walking are mediated by a common set of lower-limb muscle synergies. In humans, we examined muscle activity during multidirectional support-surface perturbations during standing and walking, as well as unperturbed walking at two speeds. We show that most muscle synergies used in perturbations responses during standing were also used in perturbation responses during walking, suggesting common neural mechanisms for reactive balance across different contexts. We also show that most muscle synergies using in reactive balance were also used during unperturbed walking, suggesting that neural circuits mediating locomotion and reactive balance recruit a common set of muscle synergies to achieve task-level goals. Differences in muscle synergies across conditions reflected differences in the biomechanical demands of the tasks. For example, muscle synergies specific to walking perturbations may reflect biomechanical challenges associated with single limb stance, and muscle synergies used during sagittal balance recovery in standing but not walking were consistent with maintaining the different desired center of mass motions in standing vs. walking. Thus, muscle synergies specifying spatial organization of muscle activation patterns may define a repertoire of biomechanical subtasks available to different neural circuits governing walking and reactive balance and may be recruited based on task-level goals. Muscle synergy analysis may aid in dissociating deficits in spatial vs. temporal organization of muscle activity in motor deficits. Muscle synergy analysis may also provide a more generalizable assessment of motor function by identifying whether common modular mechanisms are impaired across the performance of multiple motor tasks.

Chvatal, Stacie A.; Ting, Lena H.

2013-01-01

162

Random walk with shrinking steps  

NASA Astrophysics Data System (ADS)

We outline the properties of a symmetric random walk in one dimension in which the length of the nth step equals ?n, with ?<1. As the number of steps N-->?, the probability that the end point is at x approaches a limiting distribution P?(x) that has many beautiful features. For ?<1/2, the support of P?(x) is a Cantor set. For 1/2<=?<1, there is a countably infinite set of ? values for which P?(x) is singular, while P?(x) is smooth for almost all other ? values. In the most interesting case of ?=g?(5-1)/2, Pg(x) is riddled with singularities and is strikingly self-similar. This self-similarity is exploited to derive a simple form for the probability measure M(a,b)??abPg(x) dx.

Krapivsky, P. L.; Redner, S.

2004-05-01

163

Effects of a flexibility and relaxation programme, walking, and nordic walking on Parkinson's disease.  

PubMed

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

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

2011-03-30

164

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

PubMed Central

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

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

2011-01-01

165

Angular momentum of walking at different speeds.  

PubMed

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

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

2009-11-03

166

Walking dreams in congenital and acquired paraplegia.  

PubMed

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

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

2011-06-24

167

Factors influencing whether children walk to school.  

PubMed

Few studies have simultaneously evaluated multiple levels of influence on whether children walk to school. A large cohort of 4338 subjects from 10 communities was used to identify the determinants of walking through (1) a one-level logistic regression model for individual-level variables and (2) a two-level mixed regression model for individual and school-level variables. Walking rates were positively associated with home-to-school proximity, greater age, and living in neighborhoods characterized by lower traffic density. Greater land use mix around the home was, however, associated with lower rates of walking. Rates of walking to school were also higher amongst recipients of the Free and Reduced Price Meals Program and attendees of schools with higher percentage of English language learners. Designing schools in the same neighborhood as residential districts should be an essential urban planning strategy to reduce walking distance to school. Policy interventions are needed to encourage children from higher socioeconomic status families to participate in active travel to school and to develop walking infrastructures and other measures that protect disadvantaged children. PMID:23707968

Su, Jason G; Jerrett, Michael; McConnell, Rob; Berhane, Kiros; Dunton, Genevieve; Shankardass, Ketan; Reynolds, Kim; Chang, Roger; Wolch, Jennifer

2013-04-17

168

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

PubMed Central

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.

Rabkin, Janice; Sharify, Denise; Song, Lin

2009-01-01

169

Decoherence can be useful in quantum walks  

NASA Astrophysics Data System (ADS)

We present a study of the effects of decoherence in the operation of a discrete quantum walk on a line, cycle, and hypercube. We find high sensitivity to decoherence, increasing with the number of steps in the walk, as the particle is becoming more delocalized with each step. However, the effect of a small amount of decoherence is to enhance the properties of the quantum walk that are desirable for the development of quantum algorithms. Specifically, we observe a highly uniform distribution on the line, a very fast mixing time on the cycle, and more reliable hitting times across the hypercube.

Kendon, Viv; Tregenna, Ben

2003-04-01

170

An experimental analysis of human straight walking  

NASA Astrophysics Data System (ADS)

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.

Li, Tao; Ceccarelli, Marco

2013-03-01

171

Urban Walking and the Pedagogies of the Street  

ERIC Educational Resources Information Center

Drawing upon the extensive literature on urban walking and also on almost 60 years' experience of walking the streets, this article argues that there is a pressing need to re-assert the educational value of going for a walk. After a brief discussion of the social significance of the "flaneur," the historic pioneer of urban walking, the article…

Bairner, Alan

2011-01-01

172

Nordic Walking Practice Might Improve Plantar Pressure Distribution  

ERIC Educational Resources Information Center

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

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

2011-01-01

173

Why Don't Children Walk To School Anymore?  

Microsoft Academic Search

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

Rosanna Taylor

174

Online ZMP sampling search for biped walking planning  

Microsoft Academic Search

In this paper, we present a new method that uses random search for online planning of biped walking, given a feasible footstep plan. The Linear Inverted Pendulum dynamic model and the Zero Moment Point concept are employed to solve the walking problem. We consider walk planning as the choice of a sequence of ZMPs leading to a stable walk that

Jinsu Liu; Manuela M. Veloso

2008-01-01

175

Nordic Walking Practice Might Improve Plantar Pressure Distribution  

ERIC Educational Resources Information Center

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

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

2011-01-01

176

Angular momentum: Insights into walking and its control  

Microsoft Academic Search

The importance of the organization of angular momenta during walking has been suggested by the efforts of researchers to use it to control and stabilize walking robots. However, there has been little attention to the use of angular momenta as a metric of human walking or to gain insights into the control of walking. This paper analyzes the angular momemta

Bradford C. Bennett; Thomas Robert; Shawn D. Russell

2011-01-01

177

Kinematic and EMG analysis of backward walking on treadmill  

Microsoft Academic Search

The purpose of this study was to analyze the kinematics and EMG of backward walking on treadmill. There were sixteen health male subjects, aged 21-29 years, volunteered to participate in this study. The Infortronic Ultraflex Gait Analysis System was used to record the data of the five different walking patterns, including forward walking on level ground (F.W.), backward walking on

Li-Yuan ChenlY; Fong-Chin Su; Ping-Yen Chiang

2000-01-01

178

Estimation of speed and incline of walking using neural network  

Microsoft Academic Search

A portable data logger is designed to record body accelerations during human walking. Five subjects walk first on a treadmill at various speeds on the level, and at positive and negative inclines. Then, the subjects performed a self-pace walking on an outdoor test circuit involving roads of various inclines. The recorded signals are parameterized, and the pattern of walking at

Kamiar Aminian; Philippe Robert; E. Jequier; Yves Schutz

1995-01-01

179

Stabilization control for humanoid robot to walk on inclined plane  

Microsoft Academic Search

In this paper, a novel stabilization control is proposed for humanoid robot to walk dynamically on an inclined plane. Online walking control is indispensable to obtain a stable dynamic walking, even if the walking pattern is provided based on a zero moment point and an angular momentum because modeling errors and external disturbances, which are not expected in the modeling

Yong-Duk Kim; In-Won Park; Jeong-Ki Yoo; Jong-Hwan Kim

2008-01-01

180

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

Microsoft Academic Search

BackgroundTo 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 Findings79 COPD patients and 24 healthy elderly subjects performed

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

2012-01-01

181

Active knee-release mechanism for passive-dynamic walking machines and walking cycle research  

Microsoft Academic Search

Passive-dynamic walkers are mechanical devices that walk down a slope without motors or controllers. In this paper we present our research in two distinctive parts. First, a design improvement on the classical four-legged passive-dynamic walking machine and second, an investigation on the timing of different stages in the human walking cycle and comparison of the results with the results obtained

Kalin B. Trifonov; Shuji Hashimoto

2008-01-01

182

Aerobic treadmill plus Bobath walking training improves walking in subacute stroke: a randomized controlled trial  

Microsoft Academic Search

Objective: To evaluate the immediate and long-term effects of aerobic treadmill plus Bobath walking training in subacute stroke survivors compared with Bobath walking training alone.Design: Randomized controlled trial.Setting: Rehabilitation unit.Subjects: Fifty patients, first-time supratentorial stroke, stroke interval less than six weeks, Barthel Index (0 \\/ 100) from 50 to 80, able to walk a minimum distance of 12 m with

H-J Eich; H Mach; C Werner; S Hesse

2004-01-01

183

Look who's walking: social and environmental correlates of children's walking in London.  

PubMed

A substantial literature examines the social and environmental correlates of walking to school but less addresses walking outside the school commute. Using travel diary data from London, we examined social and environmental correlates of walking: to school; outside the school commute during term time; and during the summer and weekends. Living in a household without a car was associated with all journey types; 'Asian' ethnicity was negatively associated with walking for non-school travel; environmental factors were associated with non-school journeys, but not the school commute. Interventions aiming to increase children's active travel need to take account of the range of journeys they make. PMID:22464978

Steinbach, Rebecca; Green, Judith; Edwards, Phil

2012-02-22

184

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

PubMed

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

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

185

The effect of walking aids on muscle activation patterns during walking in stroke patients.  

PubMed

The purpose of this study was to investigate changes in muscle activation patterns with respect to timing and amplitude that occur when subjects with stroke walk with and without a walking aid. This knowledge could help therapists in deciding whether or not patients should use a cane or quad stick while walking. Thirteen patients suffering from a first unilateral ischemic stroke participated in the study. Surface electromyography (SEMG) of the erector spinae, gluteus maximus, gluteus medius, vastus lateralis, semitendinosus, gastrocnemius and tibialis anterior of the affected side were measured during three different conditions: (1) walking without a walking aid, (2) walking with a cane and (3) walking with a quad stick. Timing and amplitude parameters of the activation patterns were quantified using an objective burst detection algorithm and statistically evaluated. Results showed a statistically significant and clinically relevant decrease in burst duration of both erector spinae and tibialis anterior when walking with a cane. The amplitude of the vastus lateralis and tibialis anterior dropped when patients walked with a cane and quad stick. The use of a cane should be considered when therapy is given to stroke patients to achieve normal muscle activation patterns. PMID:16139752

Buurke, J H; Hermens, H J; Erren-Wolters, C V; Nene, A V

2005-10-01

186

Photons walking the line: a quantum walk with adjustable coin operations.  

PubMed

We present the first robust implementation of a coined quantum walk over five steps using only passive optical elements. By employing a fiber network loop we keep the amount of required resources constant as the walker's position Hilbert space is increased. We observed a non-Gaussian distribution of the walker's final position, thus characterizing a faster spread of the photon wave packet in comparison to the classical random walk. The walk is realized for many different coin settings and initial states, opening the way for the implementation of a quantum-walk-based search algorithm. PMID:20366754

Schreiber, A; Cassemiro, K N; Potocek, V; Gábris, A; Mosley, P J; Andersson, E; Jex, I; Silberhorn, Ch

2010-02-04

187

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 ...

188

LETTER TO THE EDITOR: Walks with ghosts  

Microsoft Academic Search

The supersymmetric formulation of the self-suppressing random walk is examined. By defining the theory as a lattice model it is shown that the supersymmetry remains unbroken throughout the physical parameter space, contrary to claims in the literature.

G. B. Tupper; F. G. Scholtz

1997-01-01

189

Power Demand in Walking and Pace Optimization.  

ERIC Educational Resources Information Center

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

Bellemans, A.

1981-01-01

190

Quantum walks with nonorthogonal position states.  

PubMed

Quantum walks have by now been realized in a large variety of different physical settings. In some of these, particularly with trapped ions, the walk is implemented in phase space, where the corresponding position states are not orthogonal. We develop a general description of such a quantum walk and show how to map it into a standard one with orthogonal states, thereby making available all the tools developed for the latter. This enables a variety of experiments, which can be implemented with smaller step sizes and more steps. Tuning the nonorthogonality allows for an easy preparation of extended states such as momentum eigenstates, which travel at a well-defined speed with low dispersion. We introduce a method to adjust their velocity by momentum shifts, which allows us to experimentally probe the dispersion relation, providing a benchmarking tool for the quantum walk, and to investigate intriguing effects such as the analog of Bloch oscillations. PMID:23368294

Matjeschk, R; Ahlbrecht, A; Enderlein, M; Cedzich, Ch; Werner, A H; Keyl, M; Schaetz, T; Werner, R F

2012-12-10

191

Power Demand in Walking and Pace Optimization.  

ERIC Educational Resources Information Center

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

Bellemans, A.

1981-01-01

192

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 ...

193

Gallery Walk Questions on Atmospheric Moisture  

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 Atmospheric Mosture. The questions are organized according to the ...

194

The random walk model of intrafraction movement.  

PubMed

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. PMID:23503362

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

2013-03-18

195

Walking with coffee: Why does it spill?  

NASA Astrophysics Data System (ADS)

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

Mayer, H. C.; Krechetnikov, R.

2012-04-01

196

Minimal walking technicolor: Setup for collider physics  

SciTech Connect

Different theoretical and phenomenological aspects of the minimal and nonminimal walking technicolor theories have recently been studied. The goal here is to make the models ready for collider phenomenology. We do this by constructing the low energy effective theory containing scalars, pseudoscalars, vector mesons, and other fields predicted by the minimal walking theory. We construct their self-interactions and interactions with standard model fields. Using the Weinberg sum rules, opportunely modified to take into account the walking behavior of the underlying gauge theory, we find interesting relations for the spin-one spectrum. We derive the electroweak parameters using the newly constructed effective theory and compare the results with the underlying gauge theory. Our analysis is sufficiently general such that the resulting model can be used to represent a generic walking technicolor theory not at odds with precision data.

Foadi, Roshan; Frandsen, Mads T.; Ryttov, Thomas A.; Sannino, Francesco [CERN Theory Division, CH-1211 Geneva 23 (Switzerland); University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen (Denmark)

2007-09-01

197

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 ...

198

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 ...

199

Gallery Walk Questions on Weather and Climate  

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 weather and climate. The questions are organized according to the ...

200

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

Federal Register 2010, 2011, 2012, 2013

...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...

2010-01-04

201

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

Federal Register 2010, 2011, 2012, 2013

...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...

2010-09-09

202

The Effects of Walking or Walking-with-Poles Training on Tissue Oxygenation in Patients with Peripheral Arterial Disease  

PubMed Central

This randomized trial proposed to determine if there were differences in calf muscle StO2 parameters in patients before and after 12 weeks of a traditional walking or walking-with-poles exercise program. Data were collected on 85 patients who were randomized to a traditional walking program (n = 40) or walking-with-poles program (n = 45) of exercise training. Patients walked for 3 times weekly for 12 weeks. Seventy-one patients completed both the baseline and the 12-week follow-up progressive treadmill tests (n = 36 traditional walking and n = 35 walking-with-poles). Using the near-infrared spectroscopy measures, StO2 was measured prior to, during, and after exercise. At baseline, calf muscle oxygenation decreased from 56 ± 17% prior to the treadmill test to 16 ± 18% at peak exercise. The time elapsed prior to reaching nadir StO2 values increased more in the traditional walking group when compared to the walking-with-poles group. Likewise, absolute walking time increased more in the traditional walking group than in the walking-with-poles group. Tissue oxygenation decline during treadmill testing was less for patients assigned to a 12-week traditional walking program when compared to those assigned to a 12-week walking-with-poles program. In conclusion, the 12-week traditional walking program was superior to walking-with-poles in improving tissue deoxygenation in patients with PAD.

Collins, Eileen G.; McBurney, Conor; Butler, Jolene; Jelinek, Christine; O'Connell, Susan; Fritschi, Cynthia; Reda, Domenic

2012-01-01

203

Back and neck muscle activity in healthy adults during barefoot walking and walking in conventional and flexible shoes  

Microsoft Academic Search

Purpose: Most studies on barefoot and shod walking have so far focused on leg muscle activity. However, footwear might also have an impact on the back and neck. The aim of the present study was to compare back and neck muscle activity as well as kinematic gait parameters during barefoot walking, conventional shod walking and walking in flexible shoes, commercially

Brigitte Wirth; Fabian Hauser; Roland Mueller

2011-01-01

204

Does getting a dog increase recreational walking?  

Microsoft Academic Search

BACKGROUND: This study examines changes in socio-demographic, environmental and intrapersonal factors associated with dog acquisition in non-dog owners at baseline to 12-months follow-up and the effect of dog acquisition on minutes per week of recreational walking. METHODS: RESIDE study participants completed self-administered questionnaires (baseline and 12-months follow-up) measuring physical activity, dog ownership, dog walking behavior as well as environmental, intrapersonal

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

2008-01-01

205

Review of walking hazards for railroad workers.  

PubMed

This is a review of walking tasks in the railroad environment, and the injuries that result from slips, trips, falls, or other acute or even non-traumatic exposures. The lack of federal regulations for railroad walkways has led several states to develop and enforce their own regulations. Support from the research literature for such regulations has come from biomechanical studies of the effects of walking on railroad ballast, which will be reviewed. PMID:22317232

Andres, Robert O; Wade, Chip

2012-01-01

206

Passive bipedal walking with phasic muscle contraction  

Microsoft Academic Search

.   The existence of self-organizing walking patterns is often considered the result of a mechanical system interacting with\\u000a the environment and a (neural) oscillating unit. The pattern generators might be thought of as an indispensable component\\u000a for the existence of limit cycle behavior. This paper shows that this is not a necessity for the existence of a self-organizing\\u000a bipedal walking

Richard Quint van der Linde

1999-01-01

207

Partially labeled classification with Markov random walks  

Microsoft Academic Search

Abstract To classify a large number,of unlabeled examples,we combine,a limited number,of labeled examples with a Markov random,walk representation over the unlabeled examples. The random,walk representation exploits any low dimensional structure in the data in a robust, probabilistic manner. We develop and compare,several estimation criteria\\/algorithms suited to this representation. This includes in particular multi-way classification with an average margin criterion which

Martin Szummer; Tommi Jaakkola

2001-01-01

208

Mesonic spectroscopy of minimal walking technicolor  

SciTech Connect

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.

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

209

Influence of non-level walking on pedometer accuracy  

Microsoft Academic Search

The YAMAX Digiwalker pedometer has been previously confirmed as a valid and reliable monitor during level walking, however, little is known about its accuracy during non-level walking activities or between genders. Subsequently, this study examined the influence of non-level walking and gender on pedometer accuracy. Forty-six healthy adults completed 3-min bouts of treadmill walking at their normal walking pace during

Anthony S. Leicht; Robert G. Crowther

2009-01-01

210

Adaptive Walking in Alzheimer's Disease  

PubMed Central

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

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

2012-01-01

211

Time to prioritise safe walking.  

PubMed

This study draws on information from two recently published documents on pedestrian safety and global status of road safety to draw attention to the need to prioritize safe walking in planning and policy at local, national and international levels. The study shows that each year, more than 270 000 pedestrians lose their lives on the world's roads. The study argues that this situation need not persist because proven pedestrian safety interventions exist but do not attract the merit they deserve in many locations. The study further shows that the key risk factors for pedestrian road traffic injury such as vehicle speed, alcohol use by drivers and pedestrians, lack of infrastructure facilities for pedestrians and inadequate visibility of pedestrians are fairly well documented. The study concludes that pedestrian collisions, like all road traffic crashes, should not be accepted as inevitable because they are, in fact, both predictable and preventable. While stressing that reduction or elimination of risks faced by pedestrians is an important and achievable policy goal, the study emphasizes the importance of a comprehensive, holistic approach that includes engineering, enforcement and education measures. PMID:23701478

Toroyan, Tami; Khayesi, Meleckidzedeck; Peden, Margie

2013-01-01

212

Developmental Continuity? Crawling, Cruising, and Walking  

PubMed Central

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.

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

2010-01-01

213

Convergence of quantum random walks with decoherence  

SciTech Connect

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

Fan Shimao; Feng Zhiyong; Yang, Wei-Shih [Department of Mathematics Temple University, Philadelphia, Pennsylvania 19122 (United States); Xiong Sheng [Department of Mathematics and Sciences Edward Waters College, Jacksonville, Florida 32209 (United States)

2011-10-15

214

Effect of Load Carriage on Trunk Coordination during Treadmill Walking at Increasing Walking Speed.  

National Technical Information Service (NTIS)

The purpose of this experiment was to determine the effects of walking speed and wearing a backpack on trunk coordination and upper and lower body angular momentum, Twelve subjects (5 male, 7 female, mean age, yr: mean +/- SD = 26 +/- 7.1) walked on a tre...

J. P. Obusek K. G. Holt M. LaFiandra R. Wagenaar

2001-01-01

215

On the Levy-walk Nature of Human Mobility: Do Humans Walk like Monkeys?  

Microsoft Academic Search

We report that human walk patterns closely follow Levy walk patterns commonly observed in animals such as mon- keys, birds and jackals. Our study is based on about one thousand hours of GPS traces involving 44 volunteers in various outdoor settings including two different college campuses, a metropolitan area, a theme park and a state fair. Important implications of this

Injong Rhee; Minsu Shin; Seongik Hong; Kyunghan Lee; Song Chong

216

Walking skill versus walking experience as a predictor of barrier crossing in toddlers  

Microsoft Academic Search

The aim of this study was to examine the roles of body size parameters, walking skill, and locomotor experience in determining the abilities of 14-, 18-, 24-, and 30-month-old toddlers to cross a barrier varying in height. Thresholds for barrier crossing were measured using a modified psychophysical staircase procedure, walking skill was assessed using a footprint analysis of gait, and

Shauna Kingsnorth; Mark A. Schmuckler

2000-01-01

217

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

ERIC Educational Resources Information Center

|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…

Kamien, Dorota

2008-01-01

218

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

Microsoft Academic Search

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

Shigeo Hirose; Kan Yoneda; Kazuhiko Arai; Tomoyoshi Ibe

1994-01-01

219

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

SciTech Connect

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.

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

220

Nordic walking practice might improve plantar pressure distribution.  

PubMed

Nordic walking (NW), characterized by the use of two walking poles, is becoming increasingly popular (Morgulec-Adamowicz, Marszalek, & Jagustyn, 2011). We studied walking pressure patterns of 20 experienced and 30 beginner Nordic walkers. Plantar pressures from nine foot zones were measured during trials performed at two walking speeds (preferred and 20% faster), and under two walking conditions (NW vs. normal walking). In comparison to normal walking, NW experience led to a significant (p < .05) pressure reduction of about 50% on the central metatarsals. No significant increases were detected in other foot regions. The differences between experienced and beginners during normal walking including a 40% pressure reduction on the metatarsal area, suggests that regular NW practice might also have a beneficial effect on plantar pressure when walking without poles. PMID:22276400

Pérez-Soriano, Pedro; Llana-Belloch, Salvador; Martínez-Nova, Alfonso; Morey-Klapsing, G; Encarnación-Martínez, Alberto

2011-12-01

221

Predictors of walking capacity in peripheral arterial disease patients  

PubMed Central

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.

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

2013-01-01

222

Psychometric performance of a generic walking scale (Walk-12G) in multiple sclerosis and Parkinson's disease.  

PubMed

Walking difficulties are common in neurological and other disorders, as well as among the elderly. There is a need for reliable and valid instruments for measuring walking difficulties in everyday life since existing gait tests are clinician rated and focus on situation specific capacity. The Walk-12G was adapted from the 12-item multiple sclerosis walking scale as a generic patient-reported rating scale for walking difficulties in everyday life. The aim of this study is to examine the psychometric properties of the Walk-12G in people with multiple sclerosis (MS) and Parkinson's disease (PD). The Walk-12G was translated into Swedish and evaluated qualitatively among 25 people with and without various neurological and other conditions. Postal survey (MS, n = 199; PD, n = 189) and clinical (PD, n = 36) data were used to test its psychometric properties. Respondents considered the Walk-12G relevant and easy to use. Mean completion time was 3.5 min. Data completeness was good (<5% missing item responses) and tests of scaling assumptions supported summing item scores to a total score (corrected item-total correlations >0.6). Coefficient alpha and test-retest reliabilities were >0.9, and standard errors of measurement were 2.3-2.8. Construct validity was supported by correlations in accordance with a priori expectations. Results are similar to those with previous Walk-12G versions, indicating that scale adaptation was successful. Data suggest that the Walk-12G meets rating scale criteria for clinical trials, making it a valuable complement to available gait tests. Further studies involving other samples and application of modern psychometric methods are warranted to examine the scale in more detail. PMID:21956376

Bladh, Stina; Nilsson, Maria H; Hariz, Gun-Marie; Westergren, Albert; Hobart, Jeremy; Hagell, Peter

2011-09-29

223

What causes edge fixation in walking flies?  

PubMed

The orientation of freely walking flies (female Lucilia cuprina) to lines and stripes in a circular arena is described. The following observations were made. 1. The flies walked straight towards a dark line using the frontal eye region, but a pale line on a dark background was only weakly attractive. 2. In bright conditions flies walked in a curved line towards a black-white edge, the path being convex towards the dark side of the border. The curves indicated that the flies were heading for a point about 5-10 degrees to the dark side of the edge. 3. In dim conditions the edge of a dark region was not especially attractive and flies headed towards any point in the dark area. These observations can be accounted for by assuming that the fly walks towards the darkest region in its visual field (scototaxis). In bright conditions the edges of a dark region become more attractive than its centre. This change could be explained if lateral inhibition creates a 'Mach-band' effect, making the edges appear darker than the centre. Thus, fixation behaviour in walking Lucilia females seems to be a simple taxis. PMID:2324671

Osorio, D; Srinivasan, M V; Pinter, R B

1990-03-01

224

Vection in depth during treadmill walking.  

PubMed

Vection has typically been induced in stationary observers (ie conditions providing visual-only information about self-motion). Two recent studies have examined vection during active treadmill walking--one reported that treadmill walking in the same direction as the visually simulated self-motion impaired vection (Onimaru et al, 2010 Journal of Vision 10(7):860), the other reported that it enhanced vection (Seno et al, 2011 Perception 40 747-750; Seno et al, 2011 Attention, Perception, & Psychophysics 73 1467-1476). Our study expands on these earlier investigations of vection during observer active movement. In experiment 1 we presented radially expanding optic flow and compared the vection produced in stationary observers with that produced during walking forward on a treadmill at a 'matched' speed. Experiment 2 compared the vection induced by forward treadmill walking while viewing expanding or contracting optic flow with that induced by viewing playbacks of these same displays while stationary. In both experiments subjects' tracked head movements were either incorporated into the self-motion displays (as simulated viewpoint jitter) or simply ignored. We found that treadmill walking always reduced vection (compared with stationary viewing conditions) and that simulated viewpoint jitter always increased vection (compared with constant velocity displays). These findings suggest that while consistent visual-vestibular information about self-acceleration increases vection, biomechanical self-motion information reduces this experience (irrespective of whether it is consistent or not with the visual input). PMID:23964381

Ash, April; Palmisano, Stephen; Apthorp, Deborah; Allison, Robert S

2013-01-01

225

Nordic walking improves mobility in Parkinson's disease.  

PubMed

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

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

2008-11-15

226

Learning to walk changes infants' social interactions.  

PubMed

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 infants were compared to age-matched crawling infants in a baby-walker. Independently walking infants spent significantly more time interacting with the toys and with their mothers, and also made more vocalizations and more directed gestures compared to infants in the walker. Experiment 3 tracked infants' social behaviors longitudinally across the transition from crawling and walking. Even when controlled for age, the transition to independent walking marked increased interaction time with mothers, as well as more sophisticated interactions, including directing mothers' attention to particular objects. The results suggest a developmental progression linking social interactions with milestones in locomotor development. PMID:20478619

Clearfield, Melissa W

2010-05-15

227

A walking stick for a pure akinesia patient.  

PubMed

We describe a 63-year-old female patient with pure akinesia whose gait was facilitated by a handmade converted walking stick. A posterior ventral pallidotomy had been performed, but it did not alleviate symptoms. Her husband made a walking stick with a wire loop at the bottom, perpendicular to the walking direction. When the patient stepped over the loop, the frozen gait was improved. This converted walking stick is easily made and inexpensive. Although the walking stick did not improve the patient's gait radically, use of the converted walking stick effectively improved the patient's daily life because successful treatment of pure akinesia cannot be established. PMID:11944747

Asahi, T; Hirashima, Y; Hamada, H; Shibata, T; Ikeda, H; Endo, S

2001-01-01

228

Symmetries and noise in quantum walk  

SciTech Connect

We study some discrete symmetries of unbiased (Hadamard) and biased quantum walk on a line, which are shown to hold even when the quantum walker is subjected to environmental effects. The noise models considered in order to account for these effects are the phase flip, bit flip, and generalized amplitude damping channels. The numerical solutions are obtained by evolving the density matrix, but the persistence of the symmetries in the presence of noise is proved using the quantum trajectories approach. We also briefly extend these studies to quantum walk on a cycle. These investigations can be relevant to the implementation of quantum walks in various known physical systems. We discuss the implementation in the case of NMR quantum information processor and ultracold atoms.

Chandrashekar, C. M. [Institute for Quantum Computing, University of Waterloo, N2L3G1 (Canada); Srikanth, R. [Poornaprajna Institute of Scientific Research, Devanahalli, Bangalore 562 110 (India); Raman Research Institute, Sadashiv Nagar, Bangalore 560080 (India); Banerjee, Subhashish [Raman Research Institute, Sadashiv Nagar, Bangalore 560080 (India)

2007-08-15

229

Quantum random-walk search algorithm  

NASA Astrophysics Data System (ADS)

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((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.

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

2003-05-01

230

Coin state properties in quantum walks  

PubMed Central

Recent experimental advances have measured individual coin components in discrete time quantum walks, which have not received the due attention in most theoretical studies on the theme. Here is presented a detailed investigation of the properties of M, the difference between square modulus of coin states of discrete quantum walks on a linear chain. Local expectation values are obtained in terms of real and imaginary parts of the Fourier transformed wave function. A simple expression is found for the average difference between coin states in terms of an angle ? gauging the coin operator and its initial state. These results are corroborated by numerical integration of dynamical equations in real space. The local dependence is characterized both by large and short period modulations. The richness of revealed patterns suggests that the amount of information stored and retrieved from quantum walks is significantly enhanced if M is taken into account.

Andrade, R. F. S.

2013-01-01

231

Relationship between quantum walks and relativistic quantum mechanics  

SciTech Connect

Quantum walk models have been used as an algorithmic tool for quantum computation and to describe various physical processes. This article revisits the relationship between relativistic quantum mechanics and the quantum walks. We show the similarities of the mathematical structure of the decoupled and coupled forms of the discrete-time quantum walk to that of the Klein-Gordon and Dirac equations, respectively. In the latter case, the coin emerges as an analog of the spinor degree of freedom. Discrete-time quantum walk as a coupled form of the continuous-time quantum walk is also shown by transforming the decoupled form of the discrete-time quantum walk to the Schroedinger form. By showing the coin to be a means to make the walk reversible and that the Dirac-like structure is a consequence of the coin use, our work suggests that the relativistic causal structure is a consequence of conservation of information. However, decoherence (modeled by projective measurements on position space) generates entropy that increases with time, making the walk irreversible and thereby producing an arrow of time. The Lieb-Robinson bound is used to highlight the causal structure of the quantum walk to put in perspective the relativistic structure of the quantum walk, the maximum speed of walk propagation, and earlier findings related to the finite spread of the walk probability distribution. We also present a two-dimensional quantum walk model on a two-state system to which the study can be extended.

Chandrashekar, C. M. [Institute for Quantum Computing, University of Waterloo, Ontario N2L 3G1 (Canada); Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 (Canada); Banerjee, Subhashish [Chennai Mathematical Institute, Padur PO, Siruseri 603 103 (India); Srikanth, R. [Poornaprajna Institute of Scientific Research, Devanahalli, Bangalore 562 110 (India); Raman Research Institute, Sadashiva Nagar, Bangalore 560 080 (India)

2010-06-15

232

Idiopathic toe walking and sensory processing dysfunction  

PubMed Central

Background It is generally understood that toe walking involves the absence or limitation of heel strike in the contact phase of the gait cycle. Toe walking has been identified as a symptom of disease processes, trauma and/or neurogenic influences. When there is no obvious cause of the gait pattern, a diagnosis of idiopathic toe walking (ITW) is made. Although there has been limited research into the pathophysiology of ITW, there has been an increasing number of contemporary texts and practitioner debates proposing that this gait pattern is linked to a sensory processing dysfunction (SPD). The purpose of this paper is to examine the literature and provide a summary of what is known about the relationship between toe walking and SPD. Method Forty-nine articles were reviewed, predominantly sourced from peer reviewed journals. Five contemporary texts were also reviewed. The literature styles consisted of author opinion pieces, letters to the editor, clinical trials, case studies, classification studies, poster/conference abstracts and narrative literature reviews. Literature was assessed and graded according to level of evidence. Results Only one small prospective, descriptive study without control has been conducted in relation to idiopathic toe walking and sensory processing. A cross-sectional study into the prevalence of idiopathic toe walking proposed sensory processing as being a reason for the difference. A proposed link between ITW and sensory processing was found within four contemporary texts and one conference abstract. Conclusion Based on the limited conclusive evidence available, the relationship between ITW and sensory processing has not been confirmed. Given the limited number and types of studies together with the growing body of anecdotal evidence it is proposed that further investigation of this relationship would be advantageous.

2010-01-01

233

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

PubMed Central

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

2012-01-01

234

Averaged run-and-tumble walks  

NASA Astrophysics Data System (ADS)

A random walk consisting of a run phase at constant speed interrupted by tumble events is analyzed and analytically solved for arbitrary time distributions. A general expression is given for the Laplace-Fourier transform of the probability density function and for the mean square displacement averaging over initial conditions. Run-and-tumble bacteria and Lévy walks are considered as particular cases. The effects of an underlying Brownian noise are also discussed. Derived expressions can be used for a direct comparison with experimentally measured quantities.

Angelani, L.

2013-04-01

235

Walking for therapy with man's best friend.  

PubMed

Recent research has shown that older people who walk dogs are more likely than those who walk with a human companion to engage in regular exercise and show more improvement in fitness. Studies with dogs and other animals have suggested new approaches for using animals to enhance both mental and physical health in older adults. With the current intense focus on health care reform, increased use of animals as therapy may serve as a cost-effective strategy for improving and maintaining health in older adults. PMID:20210264

Cangelosi, Pamela R; Sorrell, Jeanne M

2010-03-01

236

Spectral solution of delayed random walks.  

PubMed

We develop a spectral method for computing the probability density function for delayed random walks; for such problems, the method is exact to machine precision and faster than existing approaches. In conjunction with a step function approximation and the weak Euler-Maruyama discretization, the spectral method can be applied to nonlinear stochastic delay differential equations (SDDE). In essence, this means approximating the SDDE by a delayed random walk, which is then solved using the spectral method. We carry out tests for a particular nonlinear SDDE that show that this method captures the solution without the need for Monte Carlo sampling. PMID:23214645

Bhat, H S; Kumar, N

2012-10-17

237

Random Walks as Motions on the Torus  

NASA Astrophysics Data System (ADS)

Introducing motions with variable inclinations on the torus, we intend to treat random walks as stochastic-type motions on the torus. Compared with the probability density for sojourn time of the classical harmonic oscillator, the limiting density for random walks becomes also uniform on the torus if we define new variables. The famous aresine law can be interpreted in terms of new variables and its paradoxical feature disappears. This fact suggests that we can interprete other seemingly curious phenomena in the probability theory in terms of dynamical system.

Sabata, Hideki

1981-05-01

238

Walking & Bicycling Related Items from Physical Activity Questionnaires  

Cancer.gov

Walking & Bicycling Related Items from Physical Activity Questionnaires Note: brief instructions for filling out items are included for some of the questionnaires. This list of walking/bicycling items taken from various PAQs maintains the same question

239

Adaptive Dynamic Balance of Two and Four Legged Walking Robots.  

National Technical Information Service (NTIS)

Two legged and four legged walking are the most versatile forms of land locomotion in the sense of maneuverability and the ability to traverse irregular terrain. Unfortunately, the problem of practical bipedal walking with dynamic balance has so far elude...

W. T. Miller

1996-01-01

240

Walking to Work Tied to Lower Diabetes Risk  

MedlinePLUS

... on this page, please enable JavaScript. Walking to Work Tied to Lower Diabetes Risk Car commuters have ... Aug. 6 (HealthDay News) -- People who walk to work are 40 percent less likely to develop diabetes ...

241

Quantum Random Walks - New Method for Designing Quantum Algorithms  

Microsoft Academic Search

Quantum walks are quantum counterparts of random walks. In the last 5 years, they have become one of main methods of designing\\u000a quantum algorithms. Quantum walk based algorithms include element distinctness, spatial search, quantum speedup of Markov\\u000a chains, evaluation of Boolean formulas and search on ”glued trees” graph. In this talk, I will describe the quantum walk method\\u000a for designing

Andris Ambainis

2008-01-01

242

Parkinsonism: upturned walking stick as an aid to locomotion.  

PubMed

Three parkinsonian patients are described who independently discovered that their gait was facilitated by inverting a walking stick and using the handle, carried a few inches from the ground, as a visual cue or target to step over and initiate walking. It is suggested that the "inverted" walking stick have wider application in patients with Parkinson's disease as an aid to walking, particularly if they have difficulty with step initiation and maintenance of stride length. PMID:3592954

Dunne, J W; Hankey, G J; Edis, R H

1987-06-01

243

A walking pattern generation method of humanoid robot MAHRU-R  

Microsoft Academic Search

This paper proposes an omni-directional walking pattern generation method for a humanoid robot MAHRU-R. To walk stably without\\u000a falling down, a humanoid robot needs the walking pattern. Our previous walking pattern method generated the walking pattern\\u000a with linear polynomials of the zero moment point (ZMP). It implemented the simple walking like forward\\/backward walking, side\\u000a step walking and turning. However, this

Seokmin Hong; Yonghwan Oh; Bum-Jae You; Sang-Rok Oh

2009-01-01

244

Online Walking Pattern Generation for Biped Humanoid Robot with Trunk  

Microsoft Academic Search

This paper describes an online method generating walking patterns for biped humanoid robots having a trunk. Depending on the walking command, the motion patterns of the lower-limbs are created and connected to the prewalking patterns smoothly in online. For the stability of the biped robots, the trunk and the waist motion is generated by a walking stabilization control that is

Hun-ok Lim; Yoshiharu Kaneshimat; Atsuo Takanishi

2002-01-01

245

Biologically Inspired Adaptive Dynamic Walking of a Quadruped Robot  

Microsoft Academic Search

We have been trying to induce a quadruped robot to walk with medium walking speed on ir- regular terrain based on biological concepts. We propose the necessary conditions for stable dy- namic walking on irregular terrain in general, and we design the mechanical system and the neu- ral system by comparing biological concepts with those necessary conditions described in physical

Hiroshi Kimura; Yasuhiro Fukuoka; Avis H. Cohen

246

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

ERIC Educational Resources Information Center

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

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

2002-01-01

247

The efficiency and walking speed of visually impaired people  

Microsoft Academic Search

All pedestrians have a walking speed which they prefer. This appears to be the speed which, for them, is the most physically efficient. Blind pedestrians, if allowed to set the pace when accompanied by a sighted guide, will prefer to walk at a speed which is close to that of sighted pedestrians. However, when walking independently they adopt a pace

D. D. CLARK-CARTER; A. D. HEYES; C. I. HOWARTH

1986-01-01

248

Random walk with long jumps for wireless ad hoc networks  

Microsoft Academic Search

This paper considers a random walk-based search algorithm in which the random walk occasionally makes longer jumps. The algorithm is tailored to work over wireless networks with uniform node distribution. In a classical random walk each jump has the same mean length. On the contrary, in the proposed algorithm a node may decide to double the expected jump length by

Roberto Beraldi

2009-01-01

249

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

NSDL National Science Digital Library

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.

Maine, Edc I.

2012-01-01

250

Single leg walking with integrated perception, planning and control  

Microsoft Academic Search

Describes an integrated system capable of walking over rugged terrain using a single leg suspended below a carriage that rolls along rails. To walk, the system uses a laser scanner to find a foothold, positions the leg above the foothold, contacts the terrain with the foot, and applies force enough to advance the carriage along the rails. Walking both forward

Eric Krotkov; Reid Simmons; Charles Thorpe

1990-01-01

251

Dynamic Fall Detection and Pace Measurement in Walking Sticks  

Microsoft Academic Search

Falls are increasingly among the leading causes of elderly injuries and deaths each year. Several of these victims depend on a walking stick or cane for support while walking. Rendering aid more quickly to those who fall may decrease the severity of injury in several cases. In this paper, we propose a dynamic fall detection system embedded into walking sticks

Oscar Almeida; Ming Zhang; Jyh-Charn Liu

2007-01-01

252

Effects of walking poles on lower extremity gait mechanics  

Microsoft Academic Search

WILLSON, J., M. R. TORRY, M. J. DECKER, T. KERNOZEK, and J. R. STEADMAN. Effects of walking poles on lower extremity gait mechanics. Med. Sci. Sports Exerc., Vol. 33, No. 1, 2001, pp. 142-147. Purpose: The purpose of this study was to determine whether walking with poles reduces loading to the lower extremity during level over ground walking. Methods: Three-dimensional

JOHN WILLSON; MICHAEL R. TORRY; MICHAEL J. DECKER; THOMAS KERNOZEK; J. R. STEADMAN

2001-01-01

253

Walking Control Method of Biped Locomotors on Inclined Plane  

Microsoft Academic Search

This paper describes a walking control method on inclined planes for a biped locomotor. The walking control consists of a position control, virtual compliance control and posture control. Parameters of the compliance control are changed continuously in support and swing phases. The orientation of robot’s waist is kept level by posture control. Several walking experiments on inclined planes are conducted

Yutaka Mikuriya; Hiroyuki Sunazuka; Kenji Hashimoto; Yusuke Sugahara; Masamiki Kawase; Hun-ok Lim; Takuya Hosobata; Atsuo Takanishi

2005-01-01

254

Go Naked: Diapers Affect Infant Walking  

ERIC Educational Resources Information Center

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…

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

2012-01-01

255

Robotic walking simulator for neurological gait rehabilitation  

Microsoft Academic Search

The restoration of walking capability is a key goal after stroke, traumatic brain injury and spinal cord injury. Conventional training methods, e.g. treadmill training, require great physical effort from the therapists to assist the patient. A robotic training machine would be desirable in order to improve the training and to relieve the therapists. In addition to the general robot kinematics

H. Schmidt; D. SorowkiL; S. Hesse; R. Bernhardt

2002-01-01

256

Pushing Random Walk Beyond Golden Ratio  

Microsoft Academic Search

We propose a simple modification of a well-known Random Walk algorithm for solving the Satisfiability problem and analyze its performance on random CNFs with a planted solution. We rigorously prove that the new algorithm solves the Full CNF with high probability, and for random CNFs with a planted solution of high density finds an assignment that differs from the planted

Ehsan Amiri; Evgeny S. Skvortsov

2007-01-01

257

Screenbot: Walking inverted using distributed inward gripping  

Microsoft Academic Search

Insights from biology have helped reduce the weight and increase the climbing ability of mobile robots. This paper presents Screenbot, see Fig. 1, a new 126 gram biologically-inspired robot that scales wire mesh substrates using spines. Like insects, it walks with an alternating tripod gait and maintains tension in opposing legs to keep the feet attached to the substrate. A

Gregory D. Wile; Kathryn A. Daltorio; Eric D. Diller; Luther R. Palmer; Stanislav N. Gorb; Roy E. Ritzmann; Roger D. Quinn

2008-01-01

258

Analog Computer Simulation of a Walking Dragline.  

National Technical Information Service (NTIS)

An analog computer model was developed of a large, walking dragline. This model permits changes in the configuration of the dragline, or changes in its digging cycle, to be readily investigated on a computer. As a result, it is possible to determine ways ...

P. N. Nikiforuk M. C. Zoerb

1964-01-01

259

Correlated Walks' theory for DNA denaturation.  

National Technical Information Service (NTIS)

We have shown that by using a correlated Walks' theory for the lattice gas model on a one-dimensional lattice, we can study, beside the saturation curves obtained before for the enzyme kinetics, also the DNA denaturation process. In the limit of no intera...

R. Mejdani

1994-01-01

260

Asymmetric random walks and drift-diffusion  

NASA Astrophysics Data System (ADS)

To obtain the drift-diffusion equation from an asymmetric random walk it has been required that the left and right jump probabilities are approximately equal. It is shown here that such a restriction is not needed. Using multiple scales the equation is derived, where the scales are based on the advection and diffusion scales.

Holmes, M.

2013-05-01

261

Random Walk Models for Target Tracking.  

National Technical Information Service (NTIS)

Knowledge of the position of a mobile target has often to be ascertained from knowledge of the position at an earlier time and a model of the target motion. The models considered in this research contribution are based on random walk theory and are applic...

P. J. Butterly

1975-01-01

262

A random walk model of wave propagation  

Microsoft Academic Search

This paper shows that a reasonably accurate description of propagation loss in small urban cells can be obtained with a simple stochastic model based on the theory of random walks, that accounts for only two parameters: the amount of clutter and the amount of absorption in the environment. Despite the simplifications of the model, the derived analytical solution correctly describes

Massimo Franceschetti; Jehoshua Bruck; Leonard J. Schulman

2004-01-01

263

Walking technicolor beyond the ladder approximation  

SciTech Connect

We prove that in the scale-invariant limit of walking technicolor the fermion dynamical mass function falls off exactly as 1/p when the gauge coupling ..cap alpha.. just reaches the critical value required to trigger spontaneous chiral-symmetry breaking. The proof is given to all orders in ..cap alpha...

Mahanta, U.

1989-05-15

264

Sunspot random walk and 22-year variation  

USGS Publications Warehouse

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

Love, Jeffrey J.; Rigler, E. Joshua

2012-01-01

265

Random Walks and Percolation on Trees  

Microsoft Academic Search

There is a way to define an average number of branches per vertex for an arbitrary infinite locally finite tree. It equals the exponential of the Hausdorff dimension of the boundary in an appropriate metric. Its importance for probabilistic processes on a tree is shown in several ways, including random walk and percolation, where it provides points of phase transition.

Russell Lyons

1990-01-01

266

Analyzing and recognizing walking figures in XYT  

Microsoft Academic Search

We describe a novel algorithm for gait analysis. A person walking frontoparallel to the image plane generates a characteristic “braided” pattern in a spatiotemporal (XYT) volume. Our algorithm detects this pattern, and fits it with a set of spatiotemporal snakes. The snakes can be used to find the bounding contours of the walker. The contours vary over time in a

Sourabh A. Niyogi; Edward H. Adelson

1994-01-01

267

Assessment of a Solar System Walk  

ERIC Educational Resources Information Center

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

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

2010-01-01

268

Myths about the Country Walk Case  

ERIC Educational Resources Information Center

|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…

Cheit, Ross E.; Mervis, David

2007-01-01

269

The walk and jump of Equisetum spores.  

PubMed

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

Marmottant, Philippe; Ponomarenko, Alexandre; Bienaimé, Diane

2013-09-11

270

Integrated system for single leg walking  

Microsoft Academic Search

The Carnegie Mellon University Planetary Rover project is developing a six-legged walking robot capable of autonomously navigating, exploring, and acquiring samples in rugged, unknown environments. This report describes an integrated software system capable of navigating a single leg of the robot over rugged terrain. The leg, based on an early design of the Ambler Planetary Rover, is suspended below a

Reid Simmons; Eric Krotkov; Gerry Roston

1990-01-01

271

WALKING QUADRUPED WITH SUPPORT\\/STEERING WHEELS  

Microsoft Academic Search

This paper presents a new design for a walking quadruped. It incorporates a support\\/steering axle with two wheels always in contact with the ground to ensure the quadruped can stably lift two legs during gaits. Abilities include following complex trajectories. Kinematics, forward-pose gaits, and simulation examples are presented in this paper.

Ashwin Mudigonda; Robert L. Williams

272

Matrix of Science Skills for Nature Walks  

Microsoft Academic Search

The Nature Walk program at the French International School, Hong Kong, has a high Science Content. It is used as a major scientific investigation for Primary aged students. It involves Problem Solving.It encourages the use of community and adult resources.It gives the students the right to choose their learning style by teaching the students to handle a variety of observation,

Margret Hale

1998-01-01

273

Random walk in generalized quantum theory  

SciTech Connect

One can view quantum mechanics as a generalization of classical probability theory that provides for pairwise interference among alternatives. Adopting this perspective, we 'quantize' the classical random walk by finding, subject to a certain condition of 'strong positivity', the most general Markovian, translationally invariant 'decoherence functional' with nearest neighbor transitions.

Martin, Xavier [School of Theoretical Physics, DIAS, 10 Burlington Road, Dublin 4 (Ireland); O'Connor, Denjoe [School of Theoretical Physics, DIAS, 10 Burlington Road, Dublin 4 (Ireland); Depto de Fisica, Cinvestav, Apartado Postal 70-543, Mexico D.F. 0730. (Mexico); Sorkin, Rafael D. [Perimeter Institute, Waterloo, Ontario, N2J 2W9 (Canada); Dept. of Physics, Syracuse University, Syracuse, New York, 13244-1130 (United States)

2005-01-15

274

Dynamic arm swinging in human walking  

PubMed Central

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.

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

2009-01-01

275

Developmental implications of idiopathic toe walking  

Microsoft Academic Search

Objective: To determine whether children with persistent toe walking, without suspected developmental problems, and with normal results after neurologic examination, who were seen in an orthopedic clinic demonstrate delays in language development, gross or fine motor skills, visuomotor development, sensory integration function, or evidence of behavioral problems through a comprehensive multidisciplinary evaluation.Study design: A prospective, descriptive study of 13 children

Lisa H. Shulman; Debra A. Sala; Mary Lynn Y. Chu; Patricia R. McCaul; Bonnie J. Sandler

1997-01-01

276

Random Walk in Dynamic Markovian Random Environment  

Microsoft Academic Search

We consider a model, introduced by Boldrighini, Minlos and Pellegrinotti, of random walks in dynamical random environments on the integer lattice Z^d with d>=1. In this model, the environment changes over time in a Markovian manner, independently across sites, while the walker uses the environment at its current location in order to make the next transition. In contrast with the

Antar Bandyopadhyay; Ofer Zeitouni

2005-01-01

277

Go Naked: Diapers Affect Infant Walking  

ERIC Educational Resources Information Center

|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…

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

2012-01-01

278

The Two-Dimensional Random Walk  

NSDL National Science Digital Library

This is the description and instructions for the Two-Dimensional Random Walk applet. This applet, presented by Boston University's Center for Polymer Studies, relates random coin-flipping to random motion but in more than one direction (dimension). It covers mean squared distance in the discussion. Overall, this is a nice interactive resource for a statistics classroom.

Trunfio, Paul; Mcgath, Gary

2008-12-29

279

Exploring complex networks through random walks  

NASA Astrophysics Data System (ADS)

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

Costa, Luciano Da Fontoura; Travieso, Gonzalo

2007-01-01

280

Sunspot random walk and 22-year variation  

NASA Astrophysics Data System (ADS)

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

Love, Jeffrey J.; Rigler, E. Joshua

2012-05-01

281

Random walks in a Dirichlet environment  

Microsoft Academic Search

This paper states a law of large numbers for a random walk in a random iid environment on ${\\\\mathbb Z}^d$, where the environment follows some Dirichlet distribution. Moreover, we give explicit bounds for the asymptotic velocity of the process and also an asymptotic expansion of this velocity at low disorder.

Nathanaël Enriquez; Christophe Sabot

2005-01-01

282

Computer animation of human walking: a survey  

Microsoft Academic Search

: This paper surveys the set of techniques developed in Computer Graphics foranimating human walking. We first focus on the evolution from purely kinematic "knowledgebased" methods to approaches that incorporate dynamics constraints, or use dynamics simulationsto generate motion. We lastly review the recent advances on motion editing, thatenable the control of complex animations by interactively blending and tuning synthetic orcaptured

Franck Multon; Laure France; Marie-paule Cani; Gilles Debunne

1999-01-01

283

Computer Animation of Human Walking: a Survey  

Microsoft Academic Search

This paper surveys the set of techniques developed in Computer Graphics for animating human walking. We first focus on the evolution from purely kinematic "knowledge-based" methods to approaches that incorporate dynamics constraints, or use dynamics simulations to generate motion. We lastly review the recent advances on motion editing, that enable the control of complex animations by interactively blending and tuning

Franck Multon; Laure France; Marie-Paule Cani-Gascuel; Giles Debunne

1998-01-01

284

Navajo Stories of the Long Walk Period.  

ERIC Educational Resources Information Center

Presented by Navajo narrators for the Navajo people, this collection of stories reflects the Navajo perception of Navajo history and the "Long Walk" to Fort Sumner, emphasizing Navajo insight rather than historical events placed in chronological sequence. Collectively, these 40 stories reflect the following Navajo perceptions: events recalled in…

Johnson, Broderick H., Ed.

285

Stick Insects Walking Along Inclined Surfaces  

Microsoft Academic Search

SYNOPSIS. In the experiments stick insects walk on an inclined substrate such that the legs of one side of the body point uphill and the legs of the other side point downhill. In this situation the vertical axis of the body is rotated against the inclination of the substrate as if to compensate for the effect of substrate incli- nation.

BERND DIEDERICH; M ICHAEL SCHUMM; HOLK CRUSE

2002-01-01

286

Stick Insects Walking Along Inclined Surfaces1  

Microsoft Academic Search

SYNOPSIS. In the experiments stick insects walk on an inclined substrate such that the legs of one side of the body point uphill and the legs of the other side point downhill. In this situation the vertical axis of the body is rotated against the inclination of the substrate as if to compensate for the effect of substrate incli- nation.

BERND DIEDERICH; M ICHAEL SCHUMM; HOLK CRUSE

2002-01-01

287

A WOMAN'S WALK: ATTRACTIVENESS IN MOTION  

Microsoft Academic Search

Men are attracted to the movements of women's bodies. The aim of this paper is to answer the question: what is the mechanism? The role of the peak shift effect in perceptions of physical attractiveness involving women's waist to hip ratios (WHRs) in biological motion is presented. Photographs of a coordinated motor pattern, walking, are investigated with a novel measurement

James F. Doyle

2009-01-01

288

The function of the legs in the free walking stick insect,Carausius morosus  

Microsoft Academic Search

1.The function of the legs of a free walking mature stick insect (Carausius morosus) is investigated in four different walking situations: walks on a horizontal path, walks on a horizontal plane, walks on a horizontal beam with the body hanging from the beam and walks up a vertical path.2.The geometrical data, which are necessary to describe the movement of the

H. Cruse

1976-01-01

289

Wheeling Walks: A Community Campaign Using Paid Media to Encourage Walking Among Sedentary Older Adults  

Microsoft Academic Search

Background. Mass media may effect communitywide changes in health awareness, attitude, and behavior, but the approach remains unproven for physical activity.Methods. Wheeling Walks promoted walking among sedentary 50- to 65-year-old adults in a West Virginia city of 31,420 people. This quasi-experimental communication intervention used theory of planned behavior and transtheoretical model constructs to change behavior by promoting 30 min of

Bill Reger; Linda Cooper; Steven Booth-Butterfield; Holli Smith; Adrian Bauman; Margo Wootan; Susan Middlestadt; Bess Marcus; Felicia Greer

2002-01-01

290

Energy efficient walking with central pattern generators: from passive dynamic walking to biologically inspired control  

Microsoft Academic Search

Like human walking, passive dynamic walking—i.e.walkingdownaslopewithnoactuationexcept gravity—is energy efficient by exploiting the natural dynam- ics. In the animal world, neural oscillators termed central pattern generators (CPGs) provide the basic rhythm for mus- cularactivityinlocomotion.WepresentaCPGmodel,which automatically tunes into the resonance frequency of the pas- sive dynamics of a bipedal walker, i.e. the CPG model exhib- its resonance tuning behavior. Each leg is

B. W. Verdaasdonk; H. F. J. M. Koopman; Frans C. T. Van Der Helm

2009-01-01

291

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

PubMed

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

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

2006-03-01

292

Comparison of Walking Parameters and Cardiorespiratory Changes during the 6Minute Walk Test in Healthy Sexagenarians and Septuagenarians  

Microsoft Academic Search

Background: The 6-minute walk test (6-MWT) is commonly used in research, with a focus on walking distance parameters rather than the physiological parameters. Even though it has been reported that the distance walked during the 6-MWT decreases with age, the adaptation of cardiorespiratory functions in healthy older adults remains to be studied. Objectives: The primary objective of this study was

Cindy L. Hovington; Sylvie Nadeau; Alain Leroux

2009-01-01

293

A walking motion imitation framework of a humanoid robot by human walking recognition from IMU motion data  

Microsoft Academic Search

Teleoperation of humanoid robots, which is one of good methods of humanoid utilization, has difficulties in locomotion with self-balancing. In this paper, we propose a framework of walking imitation between human and a humanoid robot. Using inertial measurement unit (IMU), human's walking motions are recognized, and used as humanoid robot control inputs for on-line walking imitation. Appropriate IMU feature data

Sung-Kyun Kim; Seokmin Hong; Doik Kim

2009-01-01

294

NetLogo Models Library: Random Walk 360  

NSDL National Science Digital Library

Agent-based model produced using NetLogo that demonstrates random walks and diffusion. In this model the turtles engage in a "random walk." Each turtle walks one step away from its current location in a different random direction at each clock tick. This movement is known as walking a 360-gon "lattice." A lattice is a set of points on the plane (or in space) that form a grid on which turtles walk. As the simulation continues, one can expect the turtles to become more spread out. Will they ever return home (to their point of origin at 0 0)? Observe the kinds of patterns that develop as the turtles move.

Wilensky, Uri

295

Universal quantum computation using the discrete-time quantum walk  

SciTech Connect

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

Lovett, Neil B.; Cooper, Sally; Everitt, Matthew; Trevers, Matthew; Kendon, Viv [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)

2010-04-15

296

Langevin Picture of Lévy Walks and Their Extensions  

NASA Astrophysics Data System (ADS)

In this paper we derive Langevin picture of Lévy walks. Applying recent advances in the theory of coupled continuous time random walks we find a limiting process of the properly scaled Lévy walk. Next, we introduce extensions of Levy walks, in which jump sizes are some functions of waiting times. We prove that under proper scaling conditions, such generalized Lévy walks converge in distribution to the appropriate limiting processes. We also derive the corresponding fractional diffusion equations and investigate behavior of the mean square displacements of the limiting processes, showing that different coupling functions lead to various types of anomalous diffusion.

Magdziarz, Marcin; Szczotka, W?adys?aw; ?ebrowski, Piotr

2012-04-01

297

Can treadmill walking be used to assess propulsion generation?  

PubMed Central

Instrumented treadmills offer significant advantages for analysis of human locomotion, including recording consecutive steady-state gait cycles, precisely controlling walking speed, and avoiding force plate targeting. However, some studies of hemiparetic walking on a treadmill have suggested that the moving treadmill belt may fundamentally alter propulsion mechanics. Any differences in propulsion mechanics during treadmill walking would be problematic since recent studies assessing propulsion have provided fundamental insight into hemiparetic walking. The purpose of this study was to test the hypothesis that there would be no difference in the generation of anterior/posterior (A/P) propulsion by performing a carefully controlled comparison of the A/P ground reaction forces (GRFs) and impulses in healthy adults during treadmill and overground walking. Gait data were collected from eight subjects walking overground and on a treadmill with speed and cadence controlled. Peak negative and positive horizontal GRFs in early and late stance, respectively, were reduced by less than 5% of body weight (p < 0.05) during treadmill walking compared to overground walking. The magnitude of the braking impulse was similarly lower (p < 0.05) during treadmill walking, but no significant difference was found between propulsion impulses. While there were some subtle differences in A/P GRFs between overground and treadmill walking, these results suggest there is no fundamental difference in propulsion mechanics. We conclude that treadmill walking can be used to investigate propulsion generation in healthy and by implication clinical populations.

Goldberg, Evan J.; Kautz, Steven A.; Neptune, Richard R.

2008-01-01

298

Cardiovascular Responses Associated with Daily Walking in Subacute Stroke  

PubMed Central

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.

Prajapati, Sanjay K.; Gage, William H.; McIlroy, William E.

2013-01-01

299

Factors for Lower Walking Speed in Persons with Multiple Sclerosis  

PubMed Central

Objective. The purpose of this study was to analyze factors related to lower walking speed in persons with multiple sclerosis (PwMS). Methods. A cross-sectional survey was conducted. The study participants were 120 consecutive PwMS, who were able to walk, even with device assistance. Demographic and clinical data were collected. Walking speed was measured in 10 m walk test. Possible factors were assessed: disability, fatigue, visual functioning, balance confidence, physical activity level, walking impact, cognitive interference, and motor planning. A forward linear multiple regression analysis examined the correlation with lower speed. Results. Lower walking speed was observed in 85% of the patients. Fatigue (41%), recurrent falls (30%), and balance problems were also present, even with mild disability (average EDSS = 2.68). A good level of physical activity was noted in most of the subjects. Dual-task procedure revealed 11.58% of walking speed reduction. Many participants (69.57%) imagined greater walking speed than motor execution (mean ? 28.42%). Physical activity level was the only characteristic that demonstrated no significant difference between the groups (lower versus normal walking speed). Many mobility measures were correlated with walking speed; however, disability, balance confidence, and motor planning were the most significant. Conclusions. Disability, balance confidence, and motor planning were correlated with lower walking speed.

Nogueira, Leandro Alberto Calazans; dos Santos, Luciano Teixeira; Sabino, Pollyane Galinari; Alvarenga, Regina Maria Papais; Santos Thuler, Luiz Claudio

2013-01-01

300

Dynamics of Human Walking at Steady Speeds  

NASA Astrophysics Data System (ADS)

Biped locomotion is discussed through a Lagrangian formulation for velocity-dependent, body driving forces. An analysis of level walking in humans is given through the known experimental data on the ground-reaction force and the external work without recourse to inverted-pendulum modeling. At a certain speed, rectilinear motion of the center of mass with its backward rotation along a shortened hypocycloid is ensured by double-frequency nonlinear oscillations, whose energy cost is 1% of the external work. With increasing speed, a peculiarity and an instability of the trajectory indicate, respectively, a slow-to-normal gait crossover and the maximal fast walking speed. Key words: integrative biology, biped locomotion, human gaits, muscles.

Kokshenev, Valery B.

2004-11-01

301

Hitting time for the continuous quantum walk  

NASA Astrophysics Data System (ADS)

A new definition of hitting (absorbing) time is formulated for the case of continuous quantum walks. The walk is measured randomly according to a Poisson process with measurement rate ?. We derive an explicit formula for the hitting time and explore its dependence on the measurement rate. We show that in the two limits of the measurement rate going to 0 or infinity the hitting time diverges, where the second limit is representative of the quantum Zeno effect. Several different conditions for existence of infinite hitting time are proven by analyzing the analytical structure of the formula for the infinite hitting time. A different condition for existence of infinite hitting times based on the disconnectedness of the complementary graph is proven as well.

Varbanov, Martin

2008-03-01

302

Holographic integral equations and walking technicolor  

SciTech Connect

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)

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

2010-01-15

303

Unidirectional quantum walks: Evolution and exit times  

NASA Astrophysics Data System (ADS)

In this paper we focus our attention on a particle that follows a unidirectional quantum walk, an alternative version of the currently widespread discrete-time quantum walk on a line. Here the walker at each time step can either remain in place or move in a fixed direction, e.g., rightward or upward. While both formulations are essentially equivalent, the present approach leads us to consider discrete Fourier transforms, which eventually results in obtaining explicit expressions for the wave functions in terms of finite sums and allows the use of efficient algorithms based on the fast Fourier transform. The wave functions here obtained govern the probability of finding the particle at any given location but determine as well the exit-time probability of the walker from a fixed interval, which is also analyzed.

Montero, Miquel

2013-07-01

304

Record Statistics for Multiple Random Walks  

Microsoft Academic Search

We study the statistics of the number of records R_{n,N} for N identical and independent symmetric discrete-time random walks of n steps in one dimension, all starting at the origin at step 0. At each time step, each walker jumps by a random length drawn independently from a symmetric and continuous distribution. We consider two cases: (I) when the variance

Gregor Wergen; Satya N. Majumdar; Gregory Schehr

2012-01-01

305

The compass rose andrand om walk tests  

Microsoft Academic Search

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

Yue Fang

2002-01-01

306

A Random Walk Picture of Basketball  

NASA Astrophysics Data System (ADS)

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.

Gabel, Alan; Redner, Sidney

2012-02-01

307

Random Walks in a Random Environment  

Microsoft Academic Search

Let $\\\\{\\\\alpha_n\\\\}$ be a sequence of independent, identically distributed random variables with $0 \\\\leqq \\\\alpha_n \\\\leqq 1$ for all $n$. The random walk in a random environment on the integers is the sequence $\\\\{X_n\\\\}$ where $X_0 = 0$ and inductively $X_{n+1} = X_n + 1, (X_n - 1)$, with probability $\\\\alpha_{X_n}, (1 - \\\\alpha_{X_n})$. In this paper we consider limit

Fred Solomon

1975-01-01

308

Fractal landscape analysis of DNA walks.  

PubMed

By mapping nucleotide sequences onto a "DNA walk", we uncovered remarkably long-range power law correlations [Nature 356 (1992) 168] that imply a new scale invariant property of DNA. We found such long-range correlations in intron-containing genes and in non-transcribed regulatory DNA sequences, but not in cDNA sequences or intron-less genes. In this paper, we present more explicit evidences to support our findings. PMID:11537104

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

1992-12-15

309

Walking, fitness, body composition and inch loss  

Microsoft Academic Search

Twenty-two women aged 53.4±8.6 years (mean ± SD) walked four nights per week for eight weeks at 76% of maximum heart rate in an indoor facility. The women maintained their regular diet as evidenced by comparison of three-day diet records before and during the study. The fitness level of the women improved. Resting heart rate improved from 78.2±9.9 beats per

E. A. Bergman; J. C. Boyungs; E. Joseph

1996-01-01

310

A correlated Walks' theory for DNA denaturation  

NASA Astrophysics Data System (ADS)

We have shown that by using a correlated Walks' theory for the lattice gas model on a one-dimensional lattice, we can study, beside the saturation curves obtained before for the enzyme kinetics, also the DNA denaturation process. In the limit of no interactions between sites the equation for melting curves of DNA reduces to the random model equation. Thus our leads naturally to this classical equation in the limiting case.

Mejdani, R.

1994-08-01

311

A home-based behavioral intervention to promote walking in sedentary ethnic minority women: project WALK.  

PubMed

A home-based telephone and mail intervention was evaluated for its effectiveness in promoting walking in a sample of sedentary, ethnic minority women. One hundred twenty-five women (ages 23-54) were randomly assigned to behavioral or brief educational interventions. Women in the 8-week behavioral condition received behavior change materials through the mail and 6 structured telephone counseling sessions. Educational condition participants received a single 5-min telephone call and educational information. Both groups reported significantly increased walking at a 2-month posttest (M change = 86 and 81 min per week for behavioral and educational groups, respectively) and 5-month follow-up (M change = 40 and 52 min per week). A 30-month follow-up of 50 participants indicated both groups continued to report more walking than at baseline. The behavioral intervention was not superior to the educational condition at any assessment point. The findings may be explained as (a) both interventions were equally effective, so extensive telephone counseling is unnecessary; (b) changes over time reflected secular trends; or (c) increases in self-reported walking may be due to socially desirable reporting. Other strategies need to be evaluated for promoting walking that are tailored to the needs of ethnic minority women. PMID:9520605

Chen, A H; Sallis, J F; Castro, C M; Lee, R E; Hickmann, S A; William, C; Martin, J E

1998-01-01

312

Random walks on generalized Koch networks  

NASA Astrophysics Data System (ADS)

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.

Sun, Weigang

2013-10-01

313

Visual Evoked Responses During Standing and Walking  

PubMed Central

Human cognition has been shaped both by our body structure and by its complex interactions with its environment. Our cognition is thus inextricably linked to our own and others’ motor behavior. To model brain activity associated with natural cognition, we propose recording the concurrent brain dynamics and body movements of human subjects performing normal actions. Here we tested the feasibility of such a mobile brain/body (MoBI) imaging approach by recording high-density electroencephalographic (EEG) activity and body movements of subjects standing or walking on a treadmill while performing a visual oddball response task. Independent component analysis of the EEG data revealed visual event-related potentials that during standing, slow walking, and fast walking did not differ across movement conditions, demonstrating the viability of recording brain activity accompanying cognitive processes during whole body movement. Non-invasive and relatively low-cost MoBI studies of normal, motivated actions might improve understanding of interactions between brain and body dynamics leading to more complete biological models of cognition.

Gramann, Klaus; Gwin, Joseph T.; Bigdely-Shamlo, Nima; Ferris, Daniel P.; Makeig, Scott

2010-01-01

314

Visual evoked responses during standing and walking.  

PubMed

Human cognition has been shaped both by our body structure and by its complex interactions with its environment. Our cognition is thus inextricably linked to our own and others' motor behavior. To model brain activity associated with natural cognition, we propose recording the concurrent brain dynamics and body movements of human subjects performing normal actions. Here we tested the feasibility of such a mobile brain/body (MoBI) imaging approach by recording high-density electroencephalographic (EEG) activity and body movements of subjects standing or walking on a treadmill while performing a visual oddball response task. Independent component analysis of the EEG data revealed visual event-related potentials that during standing, slow walking, and fast walking did not differ across movement conditions, demonstrating the viability of recording brain activity accompanying cognitive processes during whole body movement. Non-invasive and relatively low-cost MoBI studies of normal, motivated actions might improve understanding of interactions between brain and body dynamics leading to more complete biological models of cognition. PMID:21267424

Gramann, Klaus; Gwin, Joseph T; Bigdely-Shamlo, Nima; Ferris, Daniel P; Makeig, Scott

2010-10-29

315

Walking technicolor signatures at hadron colliders  

SciTech Connect

Aspects of the dynamics of walking technicolor models are expected to have important consequences for technihadron production at hadron colliders. Hard-mass enhancements characteristic of walking technicolor raise technipion ({pi}{sub {ital T}}) masses relative to technirho ({rho}{sub {ital T}}) masses so that the decays {rho}{sub {ital T}}{r arrow}{pi}{sub {ital T}}{pi}{sub {ital T}} are either suppressed or forbidden altogether. Thus, {rho}{sub {ital T}} can be unusually narrow with unconventional decay modes. Large weak isospin breaking in {ital U}- and {ital D}-technifermion masses (required for {ital t}-{ital b} splitting) leads to neutral {rho}{sub {ital T}} and {pi}{sub {ital T}} that are ideally mixed. Finally, multiscale models of walking technicolor in which the light-scale technifermions carry ordinary SU(3) color can have color-octet {rho}{sub {ital T}}'s which are produced strongly in parton-parton collisions and are within reach of the Fermilab Tevatron. These would appear as narrow, well-separated {rho}{sub {ital {bar D}}{ital D}} and {rho}{sub {ital {bar U}}{ital U}} resonances in dijet production or in {pi}{sub {ital T}}{pi}{sub {ital T}} production with a limited number of final states.

Lane, K.; Ramana, M.V. (Physics Department, Boston University, Boston, Massachusetts (USA))

1991-11-01

316

Efficacy of Nordic walking in obesity management.  

PubMed

The effects of a Nordic walking (NW) program compared to those of a walking (W) program on physiological and perceptual variables in obese middle-aged women were investigated. Subjects (n=12 NW group, n=11 W group) trained over 12 weeks 3 times.week (-1). Body mass, body mass index (BMI), body fat, heart rate (HR), resting blood pressure, peak oxygen consumption (V?O (2peak)) were measured before and after the training period. Moreover, HR, rating of perceived exertion (RPE) and adherence were recorded during all training sessions. After the training period body mass, body fat and diastolic blood pressure decreased in both groups (P<0.05) whereas V?O (2peak) increased in the NW group (+3.7?ml.min (-1).kg (-1); P=0.005). During the training sessions, mean HR (P=0.021), HR at preferred walking speed (P=0.020) and % of time at high intensity (P=0.031) were higher in NW than in the W group. Finally, RPE was not influenced by the modality of exercise and NW group showed a higher rate of adherence (91±19% vs. 81±29%; P=0.011). To conclude, NW activity in obese women allows an increase in exercise intensity and adherence to a training program without increasing the perception of effort leading to enhanced aerobic capacity. PMID:21472629

Figard-Fabre, H; Fabre, N; Leonardi, A; Schena, F

2011-04-06

317

The variability problem of normal human walking.  

PubMed

Previous investigations have suggested considerable inter-individual variability in the time course pattern of net joint moments during normal human walking, although the limited sample sizes precluded statistical analyses. The purpose of the present study was to obtain joint moment patterns from a group of normal subjects and to test whether or not the expected differences would prove to be statistically significant. Fifteen healthy male subjects were recorded on video while they walked across two force platforms. Ten kinematic and kinetic parameters were selected and input to a statistical cluster analysis to determine whether or not the 15 subjects could be divided into different 'families' (clusters) of walking strategy. The net joint moments showed a variability corroborating earlier reports. The cluster analysis showed that the 15 subjects could be grouped into two clusters of 5 and 10 subjects, respectively. Five parameters differed significantly, so the group of 5 subjects was characterized by (1) a higher peak knee joint extensor moment, (2) more flexed knee joint angle at heel strike, (3) during the whole stance phase, (4) lower peak knee joint flexor moment and (5) lower ankle joint angle at flat foot position. Calculation of bone-on-bone forces in the knee joint showed a value of 64 N/kg body weight in the K+ group and 55 N/kg in the K- group (p<0.05). It is unknown if differences of similar magnitude contribute to early joint degeneration in some individuals while not in others. PMID:21852174

Simonsen, Erik B; Alkjær, Tine

2011-08-17

318

Maximal-entropy random walk unifies centrality measures  

NASA Astrophysics Data System (ADS)

This paper compares a number of centrality measures and several (dis-)similarity matrices with which they can be defined. These matrices, which are used among others in community detection methods, represent quantities connected to enumeration of paths on a graph and to random walks. Relationships between some of these matrices are derived in the paper. These relationships are inherited by the centrality measures. They include measures based on the principal eigenvector of the adjacency matrix, path enumeration, as well as on the stationary state, stochastic matrix, or mean first-passage times of a random walk. As the random walk defining the centrality measure can be arbitrarily chosen, we pay particular attention to the maximal-entropy random walk, which serves as a very distinct alternative to the ordinary (diffusive) random walk used in network analysis. The various importance measures, defined both with the use of ordinary random walk and the maximal-entropy random walk, are compared numerically on a set of benchmark graphs with varying mixing parameter and are grouped with the use of the agglomerative clustering technique. It is shown that centrality measures defined with the two different random walks cluster into two separate groups. In particular, the group of centrality measures defined by the maximal-entropy random walk does not cluster with any other measures on change of graphs’ parameters, and members of this group produce mutually closer results than members of the group defined by the ordinary random walk.

Ochab, J. K.

2012-12-01

319

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

PubMed

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

Phadke, Chetan P

2012-04-01

320

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

PubMed Central

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.

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

2013-01-01

321

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

PubMed

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

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

2013-09-01

322

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

PubMed Central

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.

2012-01-01

323

Walking with coffee: when and why coffee spills  

NASA Astrophysics Data System (ADS)

In our busy lives, almost all of us have to walk with a cup of coffee. Needless to say, under certain conditions we spill that precious liquid. This is a common example of the interplay between the mechanics of the complex motion of a walking individual and the fluid dynamics of a low viscosity liquid contained in a cup. We report on the results of an experimental investigation undertaken to explore the particular conditions under which coffee spills. Frame-by-frame analysis of recorded movies helps to elucidate the trajectory of the cup for various walking speeds and initial liquid levels. These kinematics, including both regular and irregular motions, are connected to instances during walking that result in spilled liquid. The coupling between mechanical aspects of walking and the fluid motion are analyzed based on which we determine a basic operational space with which one can confidently walk with cup in hand.

Mayer, Hans C.; Krechetnikov, Rouslan

2011-11-01

324

Black Holes, Space-Filling Chains and Random Walks  

NASA Astrophysics Data System (ADS)

Many approaches to a semiclassical description of gravity lead to an integer black hole entropy. In four dimensions this implies that the Schwarzschild radius obeys a formula which describes the distance covered by a Brownian random walk. For the higher-dimensional Schwarzschild-Tangherlini black hole, its radius relates similarly to a fractional Brownian walk. We propose a possible microscopic explanation for these random walk structures based on microscopic chains which fill the interior of the black hole.

Krause, Axel

325

ARAMIES: A Four-legged Climbing and Walking Robot  

Microsoft Academic Search

This article describes the four-legged walking inte- gration study ARAMIES and the developed control software approach. Furthermore, we analyze a first walking experiment carried out. We explain how CPG-like rhythmic motion patterns can be produced on the basis of Bezier-splines, resulting in a very simple and flexible way to produce complex walk- ing trajectories which can be modulated in phase,

Dirk Spenneberg; M. Albrecht; T. Backhaus; J. Hilljegerdes; F. Kirchner; H. Zschenker

2005-01-01

326

Further Steps Toward More Humanlike Passive Bipedal Walking Robots  

Microsoft Academic Search

This paper describes two-legged mechanical structure with ankle, knee and hip joints that is capable of walking in naturally stable walking cycle on downhill slope without presence of energy source. Bipedal model has elastic strings attached to the designated places that imitate a part of human muscular-skeletal system. By combining spring-like properties with passive walking principles we accomplish energy exchanges

Andrej Olensek; Zlatko Matjacic

2005-01-01

327

A New Family of Solvable Pearson-Dirichlet Random Walks  

Microsoft Academic Search

An n-step Pearson-Gamma random walk in ?\\u000a d\\u000a starts at the origin and consists of n independent steps with gamma distributed lengths and uniform orientations. The gamma distribution of each step length has\\u000a a shape parameter q>0. Constrained random walks of n steps in ?\\u000a d\\u000a are obtained from the latter walks by imposing that the sum of the step

Gérard Le Caër

2011-01-01

328

A New Family of Solvable Pearson-Dirichlet Random Walks  

Microsoft Academic Search

An n-step Pearson-Gamma random walk in R d starts at the origin and consists of n independent steps with gamma distributed lengths and uniform orientations. The gamma distribution of each step length has a shape parameter q>0. Constrained random walks of n steps in R d are obtained from the latter walks by imposing that the sum of the step

Gérard Le Caër

2011-01-01

329

A biped walking robot having a ZMP measurement system using universal force-moment sensors  

Microsoft Academic Search

Concerns the use of the zero moment point (ZMP) as a criterion in order to distinguish the stability of walking for a biped walking robot. If the ZMP during walking can be measured, it is possible for a biped walking robot to realize stabler walking by a control method that makes use of the measured ZMP. A method of measuring

Qinghua Li; Atsuo Takanishi; Ichiro Kato

1991-01-01

330

Stabilizing biped walking on rough terrain based on the compliance control  

Microsoft Academic Search

In this paper, we propose a control system that changes the compliance based on the walking speed to stabilize biped walking on rough terrain. The proposed system does not use the inclination of the terrain. Instead, the system changes walking modes depends on its walking speed. In the downhill terrain, when the walking speed is increased, the stiffness of the

Masaki Ogino; Hiroyuki Toyama; Minoru Asada

2007-01-01

331

The effect of hip arthroplasty on the speed of walking.  

PubMed

Osteoarthritis of the hip presents itself with gait disturbances, such as decreased speed of walking and limp, regardless of the presence of pain. In most cases, patients decide to undergo surgical procedure as a result of pain and walking difficulties. The purpose of this study was to analyze gait speed in a group of 86 patients who have undergone hip arthroplasty. The methodology has consisted of analysis of walking speed over a distance of 20 meters performed prior to and following surgical treatment. The results indicated that, in most cases, surgical treatment was associated with significant improvement in the speed of walking.   PMID:24042091

Pogorza?a, Adam M; Stry?a, Wanda; Nowakowski, Andrzej

2013-09-15

332

Implementing quantum walks using orbital angular momentum of classical light.  

PubMed

We present an implementation scheme for a quantum walk in the orbital angular momentum space of a laser beam. The scheme makes use of a ring interferometer, containing a quarter-wave plate and a q plate. This setup enables one to perform an arbitrary number of quantum walk steps. In addition, the classical nature of the implementation scheme makes it possible to observe the quantum walk evolution in real time. We use nonquantum entanglement of the laser beam's polarization with its orbital angular momentum to implement the quantum walk. PMID:23848875

Goyal, Sandeep K; Roux, Filippus S; Forbes, Andrew; Konrad, Thomas

2013-06-28

333

Implementing Quantum Walks Using Orbital Angular Momentum of Classical Light  

NASA Astrophysics Data System (ADS)

We present an implementation scheme for a quantum walk in the orbital angular momentum space of a laser beam. The scheme makes use of a ring interferometer, containing a quarter-wave plate and a q plate. This setup enables one to perform an arbitrary number of quantum walk steps. In addition, the classical nature of the implementation scheme makes it possible to observe the quantum walk evolution in real time. We use nonquantum entanglement of the laser beam’s polarization with its orbital angular momentum to implement the quantum walk.

Goyal, Sandeep K.; Roux, Filippus S.; Forbes, Andrew; Konrad, Thomas

2013-06-01

334

Connecting the discrete- and continuous-time quantum walks  

SciTech Connect

Recently, quantized versions of random walks have been explored as effective elements for quantum algorithms. In the simplest case of one dimension, the theory has remained divided into the discrete-time quantum walk and the continuous-time quantum walk. Though the properties of these two walks have shown similarities, it has remained an open problem to find the exact relation between the two. The precise connection of these two processes, both quantally and classically, is presented. Extension to higher dimensions is also discussed.

Strauch, Frederick W. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8423 (United States)

2006-09-15

335

Fractional scaling of quantum walks on percolation lattices  

NASA Astrophysics Data System (ADS)

Quantum walks can be used to model processes such as transport in spin chains and bio-molecules. The enhanced spreading and mixing properties of quantum walks compared with their classical counterparts have been well-studied on regular structures and also shown to be sensitive to defects and imperfections. Using numerical simulation, we study the spreading properties of quantum walks on percolation lattices for both bond and site percolation. The randomly missing edges or sites provide a controlled amount of disorder in the regular Cartesian lattice. In one dimension (the line) we introduce a simple model of quantum tunneling to allow the walk to proceed past the missing edges or sites. This allows the quantum walk to spread faster than a classical random walk for short times, but at longer times the disorder localises the quantum walk. In two dimensions, we observe fractional scaling of the spreading with the number of steps of the walk. For percolation above the 85% level, we obtain faster spreading than classical random walks on the full lattice.

Kendon, Viv; Leung, Godfrey; Bailey, Joe; Knott, Paul

2011-03-01

336

Walking control of small size humanoid robot: Hajime Robot 18  

NASA Astrophysics Data System (ADS)

HAJIME ROBOT 18 is a fully autonomous biped robot. It has been developed for RoboCup which is a worldwide soccer competition of robots. It is necessary for a robot to have high mobility to play soccer. High speed walking and all directional walking are important to approach and to locate in front of a ball. HAJIME ROBOT achieved these walking. This paper describes walking control of a small size humanoid robot 'HAJIME ROBOT 18' and shows the measurement result of ZMP (Zero Moment Point). HAJIME ROBOT won the Robotics Society of Japan Award in RoboCup 2005 and in RoboCup 2006 Japan Open.

Sakamoto, Hajime; Nakatsu, Ryohei

2007-12-01

337

The mechanics of walking in children.  

PubMed Central

The work done at each step, during level walking at a constant average speed, to lift the centre of mass of the body, to accelerate it forward, and to increase the sum of both gravitational potential and kinetic energies, has been measured at various speeds on children of 2-12 years of age, with the same technique used previously for adults (Cavagna, 1975; Cavagna, Thys & Zamboni, 1976). The pendulum-like transfer between potential and kinetic energies (Cavagna et al. 1976) reaches a maximum at the speed at which the weight-specific work to move the centre of mass a given distance is at a minimum ('optimal' speed). This speed is about 2 X 8 km/hr at 2 years of age and increases progressively with age up to 5 km/hr at 12 years of age and in adults. The speed freely chosen during steady walking at the different ages is similar to this 'optimal' speed. At the 'optimal' speed, the time of single contact (time of swing) is in good agreement with that predicted, for the same stature, by a ballistic walking model assuming a minimum of muscular work (Mochon & McMahon, 1980). Above the 'optimal' speed, the recovery of mechanical energy through the potential-kinetic energy transfer decreases. This decrease is greater the younger the subject. A reduction of this recovery implies a greater amount of work to be supplied by muscles: at 4 X 5 km/hr the weight-specific muscular power necessary to move the centre of mass is 2 X 3 times greater in a 2-year-old child than in an adult.

Cavagna, G A; Franzetti, P; Fuchimoto, T

1983-01-01

338

The mechanics of walking in children.  

PubMed

The work done at each step, during level walking at a constant average speed, to lift the centre of mass of the body, to accelerate it forward, and to increase the sum of both gravitational potential and kinetic energies, has been measured at various speeds on children of 2-12 years of age, with the same technique used previously for adults (Cavagna, 1975; Cavagna, Thys & Zamboni, 1976). The pendulum-like transfer between potential and kinetic energies (Cavagna et al. 1976) reaches a maximum at the speed at which the weight-specific work to move the centre of mass a given distance is at a minimum ('optimal' speed). This speed is about 2 X 8 km/hr at 2 years of age and increases progressively with age up to 5 km/hr at 12 years of age and in adults. The speed freely chosen during steady walking at the different ages is similar to this 'optimal' speed. At the 'optimal' speed, the time of single contact (time of swing) is in good agreement with that predicted, for the same stature, by a ballistic walking model assuming a minimum of muscular work (Mochon & McMahon, 1980). Above the 'optimal' speed, the recovery of mechanical energy through the potential-kinetic energy transfer decreases. This decrease is greater the younger the subject. A reduction of this recovery implies a greater amount of work to be supplied by muscles: at 4 X 5 km/hr the weight-specific muscular power necessary to move the centre of mass is 2 X 3 times greater in a 2-year-old child than in an adult. PMID:6644619

Cavagna, G A; Franzetti, P; Fuchimoto, T

1983-10-01

339

Analysis of Human-Inspired Biped Walk Characteristics in a Prototype Humanoid Robot for Improvement of Walking Speed  

Microsoft Academic Search

This paper presents analysis of biped locomotion based on human's walking characteristics to improve walking speed in humanoid robotics. The analysis is focus on improvement of walking speed without changing reduction-ratio at the robot's joint-motor system. Three parameters are considered: step length, hip-joint height and duty-ratio. We use humanoid robot Bonten-Maru II as an analysis platform. Analysis based on simulations

Hanafiah B. Yussof; Masahiro Ohka; Mitsuhiro Yamano; Yasuo Nasu

2008-01-01

340

Energy efficient walking with central pattern generators: from passive dynamic walking to biologically inspired control.  

PubMed

Like human walking, passive dynamic walking-i.e. walking down a slope with no actuation except gravity-is energy efficient by exploiting the natural dynamics. In the animal world, neural oscillators termed central pattern generators (CPGs) provide the basic rhythm for muscular activity in locomotion. We present a CPG model, which automatically tunes into the resonance frequency of the passive dynamics of a bipedal walker, i.e. the CPG model exhibits resonance tuning behavior. Each leg is coupled to its own CPG, controlling the hip moment of force. Resonance tuning above the endogenous frequency of the CPG-i.e. the CPG's eigenfrequency-is achieved by feedback of both limb angles to their corresponding CPG, while integration of the limb angles provides resonance tuning at and below the endogenous frequency of the CPG. Feedback of the angular velocity of both limbs to their corresponding CPG compensates for the time delay in the loop coupling each limb to its CPG. The resonance tuning behavior of the CPG model allows the gait velocity to be controlled by a single parameter, while retaining the energy efficiency of passive dynamic walking. PMID:19504121

Verdaasdonk, B W; Koopman, H F J M; van der Helm, F C T

2009-06-06

341

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

Microsoft Academic Search

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

Matthew E. Kahn; Eric A. Morris

2009-01-01

342

Interlimb coordination in prosthetic walking: effects of asymmetry and walking velocity  

Microsoft Academic Search

The present study focuses on interlimb coordination in walking with an above-knee prosthesis using concepts and tools of dynamical systems theory (DST). Prosthetic walkers are an interesting group to investigate from this theory because their locomotory system is inherently asymmetric, while, according to DST, coordinative stability may be expected to be reduced as a function of the asymmetry of the

Stella F Donker; Peter J Beek

2002-01-01

343

Propagation of Quantum Walks in Electric Fields  

NASA Astrophysics Data System (ADS)

We study one-dimensional quantum walks in a homogenous electric field. The field is given by a phase which depends linearly on position and is applied after each step. The long time propagation properties of this system, such as revivals, ballistic expansion, and Anderson localization, depend very sensitively on the value of the electric field, ?, e.g., on whether ?/(2?) is rational or irrational. We relate these properties to the continued fraction expansion of the field. When the field is given only with finite accuracy, the beginning of the expansion allows analogous conclusions about the behavior on finite time scales.

Cedzich, C.; Rybár, T.; Werner, A. H.; Alberti, A.; Genske, M.; Werner, R. F.

2013-10-01

344

Light dilaton in walking gauge theories  

SciTech Connect

We analyze the existence of a dilaton in gauge theories with approximate infrared conformal symmetry. To the extent that these theories are governed in the infrared by an approximate fixed point (walking), the explicit breaking of the conformal symmetry at these scales is vanishingly small. If confinement and spontaneous chiral-symmetry breaking set in at some infrared scale, the resultant breaking of the approximate conformal symmetry can lead to the existence of a dilaton with mass parametrically small compared to the confinement scale, and potentially observable at the LHC.

Appelquist, Thomas [Department of Physics, Sloane Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Bai Yang [Theoretical Physics Department, Fermilab, Batavia, Illinois 60510 (United States)

2010-10-01

345

SLAW: A Mobility Model for Human Walks  

Microsoft Academic Search

Abstract—Simulating,human,mobility,is important,in mobile networks,because,many,mobile,devices are either attached,to or controlled by humans,and,it is very hard,to deploy,real mobile networks,whose,size is controllably scalable for performance,eval- uation. Lately various measurement,studies of human,walk traces have discovered,several significant statistical patterns of human mobility. Namely these include truncated,power-law distributions of flights, pause-times and inter-contact times, fractal way-points, and,heterogeneously,defined areas of individual mobility. Unfor- tunately, none of existing

Kyunghan Lee; Seong Joon Kim

346

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.

1997-01-01

347

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

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…

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

2012-01-01

348

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

|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…

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

2012-01-01

349

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

Code of Federal Regulations, 2010 CFR

...test method for the measurement of energy consumption of walk-in coolers and walk-in freezers. 431.304 Section 431.304 Energy...PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Walk-in Coolers and Walk-in Freezers Test...

2010-01-01

350

Coupled continuous time random walks in finance  

NASA Astrophysics Data System (ADS)

Continuous time random walks (CTRWs) are used in physics to model anomalous diffusion, by incorporating a random waiting time between particle jumps. In finance, the particle jumps are log-returns and the waiting times measure delay between transactions. These two random variables (log-return and waiting time) are typically not independent. For these coupled CTRW models, we can now compute the limiting stochastic process (just like Brownian motion is the limit of a simple random walk), even in the case of heavy-tailed (power-law) price jumps and/or waiting times. The probability density functions for this limit process solve fractional partial differential equations. In some cases, these equations can be explicitly solved to yield descriptions of long-term price changes, based on a high-resolution model of individual trades that includes the statistical dependence between waiting times and the subsequent log-returns. In the heavy-tailed case, this involves operator stable space time random vectors that generalize the familiar stable models. In this paper, we will review the fundamental theory and present two applications with tick-by-tick stock and futures data.

Meerschaert, Mark M.; Scalas, Enrico

2006-10-01

351

Theories of bipedal walking: an odyssey.  

PubMed

In this paper six theories of bipedal walking, and the evidence in support of the theories, are reviewed. They include: evolution, minimising energy consumption, maturation in children, central pattern generators, linking control and effect, and robots on two legs. Specifically, the six theories posit that: (1) bipedalism is the fundamental evolutionary adaptation that sets hominids--and therefore humans--apart from other primates; (2) locomotion is the translation of the centre of gravity along a pathway requiring the least expenditure of energy; (3) when a young child takes its first few halting steps, his or her biomechanical strategy is to minimise the risk of falling; (4) a dedicated network of interneurons in the spinal cord generates the rhythm and cyclic pattern of electromyographic signals that give rise to bipedal gait; (5) bipedal locomotion is generated through global entrainment of the neural system on the one hand, and the musculoskeletal system plus environment on the other; and (6) powered dynamic gait in a bipedal robot can be realised only through a strategy which is based on stability and real-time feedback control. The published record suggests that each of the theories has some measure of support. However, it is important to note that there are other important theories of locomotion which have not been covered in this review. Despite such omissions, this odyssey has explored the wide spectrum of bipedal walking, from its origins through to the integration of the nervous, muscular and skeletal systems. PMID:12600342

Vaughan, Christopher L

2003-04-01

352

Walk-through surveys for child labor.  

PubMed

Child labor is increasing in both developing and developed countries. Walk-through surveys were used to identify children, aged 8-15 years, working in six sites in Tel Aviv and Jerusalem, the largest cities in Israel. Of the 45 children who were interviewed, 20 were Jewish Israeli born, 19 were recent Jewish immigrants from the former Soviet Union, and six were Arabs from Judea, Samaria, and Gaza. The majority of children were either too young for employment, according to the Israeli Child Labor Laws, and/or receiving less than the legal minimum wage. Many were performing physical labor that might be expected to interfere with normal growth and development. Many of the children had visible signs of impaired physical health. Some were subjected to physical and/or verbal abuse. Walk-through surveys are recommended as a tool for routine use for surveillance of hazardous working conditions, case-finding, and evaluating the efficacy of preventive measures. The World Health Organization recommendations are emphasized to eliminate hazardous working conditions and to provide on-the-job health and social services to working children. PMID:7892831

Feingold, E; Wasser, J

1994-12-01

353

Wigner formula of rotation matrices and quantum walks  

Microsoft Academic Search

Quantization of a random-walk model is performed by giving a qudit (a multicomponent wave function) to a walker at site and by introducing a quantum coin, which is a matrix representation of a unitary transformation. In quantum walks, the qudit of the walker is mixed according to the quantum coin at each time step, when the walker hops to other

Takahiro Miyazaki; Makoto Katori; Norio Konno

2007-01-01

354

User directional intention recognition of an omnidirectional walking support walker  

Microsoft Academic Search

An omnidirectional walking support walker (ODW) is being developed. In order to provide walking support according to the user directional intention, we propose a method to recognize the user directional intention from forearm pressures. The pressures between forearms and the ODW are measured by 4 force sensors embedded in the ODW's armrest. The relationship between forearm pressure and user directional

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

2011-01-01

355

External rotation as morphological bootstrapping for emergence of biped walking  

Microsoft Academic Search

Many researchers are interested in the onset and learning of bipedal walking, but still not much is known how a human (and even a robot) can acquire the ability. In this paper, we hypothesize that external rotation of the hip joint plays an essential role for emergence of bipedal walking in human infancy. We build an infant robot “Pneu-born 13”

Koh Hosoda; Yoichiro Ishii

2010-01-01

356

Learning control for a biped walking robot with a trunk  

Microsoft Academic Search

The authors propose learning control methods for compensative trunk motion for a biped walking robot that has a trunk, based on the ZMP (zero moment point) stability criterion, for the cases of the ZMP being inside the stable region and outside the stable region, respectively. They have developed a biped walking robot with a ZMP measurement system and a support

Qinghua Li; Atsuo Takanishi; I. Kato

1993-01-01

357

A Study of Energy Saving Shoes for Walking Robot  

NASA Astrophysics Data System (ADS)

In this paper, we propose flexible shoe system to apply passive walking manner to ordinary humanoid biped. In this system, 2DOF (FF & FB) control scheme is used and realize walking with less ankle torque. The effectiveness is confirmed by computer simulation and experimental result, so we call this system as “energy saving shoes".

Minakata, Hideaki; Tadakuma, Susumu

358

Adaptive Dynamic Balance of Two and Four Legged Walking Robots.  

National Technical Information Service (NTIS)

Two-legged and four-legged walking are the most versatile forms of land locomotion in the sense of maneuverability and the ability to traverse irregular terrain. Unfortunately, the problem of practical bipedal walking with dynamic balance has so far elude...

W. T. Miller

1995-01-01

359

Factors of the physical environment associated with walking and bicycling  

Microsoft Academic Search

PURPOSE: The purpose of this study was to identify factors of the physical environment that may influence time spent on walking and bicycling. METHODS: Demographic factors and time spent on walking and bicycling (during leisure time and for commuting purposes) were assessed with a self-administered questionnaire. GIS databases were used to objectively measure the total square area of green space

G. C. WANDA WENDEL-VOS; A. JANTINE SCHUIT; RAYMOND DE NIET; HENDRIEK C. BOSHUIZEN; WIM H. M. SARIS; DAAN KROMHOUT

2004-01-01

360

Can Triaxial Accelerometry Accurately Recognize Inclined Walking Terrains?  

Microsoft Academic Search

The standard method for the analysis of body accelerations cannot accurately estimate the energy expenditure (EE) of uphill or downhill walking. The ability to recognize the grade of the walking surface will most likely improve upon the accuracy of the EE estimates for daily physical activities. This paper investigates the benefits of automatic gait analysis approaches including step-by-step gait segmentation

Ning Wang; Stephen J. Redmond; Eliathamby Ambikairajah; Branko G. Celler; Nigel H. Lovell

2010-01-01

361

[Erection while walking and stenosis of the lumbar canal].  

PubMed

Lumbar channel stenosis is frequently manifested by a Cauda Equina intermittent claudication. Only exceptionally erections during walking have been described. We have observed two patients with severe lumbar channel stenosis and a Cauda Equina syndrome with intermittent erections during walking. One patient was laminectomized presenting a clinical improvement. There does not exist a satisfactory explanation for this strange affectation. PMID:2244059

García-Albea, E; Palomo, F; Tejeiro, J

1990-06-01

362

Validity of the Nike+ device during walking and running.  

PubMed

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

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

2009-12-21

363

Elastic coupling of limb joints enables faster bipedal walking  

PubMed Central

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.

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

2008-01-01

364

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

ERIC Educational Resources Information Center

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

Mackett, Roger L.; Paskins, James

2008-01-01

365

Gait analysis for human walking paths and identities recognition  

Microsoft Academic Search

In this paper, we propose a gait analysis method which extracts the dynamic and static information from human walking for walking path and identity recognition. First, we utilize the periodicity of swing distances to estimate the gait period for each gait sequence. For each gait cycle, we extract the dynamic information by analyzing the statistic histogram of motion vectors and

Meng-Fen Ho; Ke-Zen Chen; Chung-Lin Huang

2009-01-01

366

Position-dependent and cooperative quantum Parrondo walks  

NASA Astrophysics Data System (ADS)

This work is a study on quantum computational formulations of Parrondo walks, that is, positively trending random walks formed as combinations of negatively trending random walks. We reanalyse the position-dependent walk proposed by Košík et al (2007 J. Mod. Opt. 54 2275), correcting the parameter choices in that paper to achieve the Parrondo effect. We also devise a quantum analogue of the cooperative Parrondo walk of Toral (2002 Fluct. Noise Lett. 2 L305), in which it is the interaction between multiple participants, rather than position-dependence, that allows the Parrondo effect to occur. We give a general formulation of a quantum analogue of the classical walk of Toral (2002 Fluct. Noise Lett. 2 L305), and demonstrate the Parrondo effect numerically. Lastly, we highlight a qualitative difference in asymptotic behaviour between quantum Parrondo walks and their classical counterparts. In particular, we draw attention to an intuitive but unreliable assumption, based on classical random walks, which may pose extra challenges for applications of the Parrondo effect in the quantum setting seeking to separate or classify data or particles.

Bulger, David; Freckleton, James; Twamley, Jason

2008-09-01

367

Adaptive L?vy Walks in Foraging Fallow Deer  

PubMed Central

Background Lévy flights are random walks, the step lengths of which come from probability distributions with heavy power-law tails, such that clusters of short steps are connected by rare long steps. Lévy walks maximise search efficiency of mobile foragers. Recently, several studies raised some concerns about the reliability of the statistical analysis used in previous analyses. Further, it is unclear whether Lévy walks represent adaptive strategies or emergent properties determined by the interaction between foragers and resource distribution. Thus two fundamental questions still need to be addressed: the presence of Lévy walks in the wild and whether or not they represent a form of adaptive behaviour. Methodology/Principal Findings We studied 235 paths of solitary and clustered (i.e. foraging in group) fallow deer (Dama dama), exploiting the same pasture. We used maximum likelihood estimation for discriminating between a power-tailed distribution and the exponential alternative and rank/frequency plots to discriminate between Lévy walks and composite Brownian walks. We showed that solitary deer perform Lévy searches, while clustered animals did not adopt that strategy. Conclusion/Significance Our demonstration of the presence of Lévy walks is, at our knowledge, the first available which adopts up-to-date statistical methodologies in a terrestrial mammal. Comparing solitary and clustered deer, we concluded that the Lévy walks of solitary deer represent an adaptation maximising encounter rates with forage resources and not an epiphenomenon induced by a peculiar food distribution.

Focardi, Stefano; Montanaro, Paolo; Pecchioli, Elena

2009-01-01

368

Foot placement and velocity control in smooth bipedal walking  

Microsoft Academic Search

For a walking robot to negotiate rough terrain it must adjust its step length to hit suitable footholds while simultaneously regulating its forward speed. This paper develops an algorithm to achieve these aims for a planar dynamic biped in the context of smooth exchange of support. The basis of the algorithm is an asymmetric gait to adjust walking velocity combined

Eric R. Dunn; Robert D. Howe

1996-01-01

369

Morphological integration and the evolution of knuckle-walking.  

PubMed

The evolution of knuckle-walking has profound implications for our understanding of the emergence of bipedalism. The modern debate surrounding its evolution is concerned with whether or not it is homologous in chimpanzees and gorillas. Here, this problem is approached using the methods of morphological integration to test hypotheses of patterns and magnitudes of integration in the third manual ray and capitate. If knuckle-walking morphologies are highly integrated and evolve in a correlated bundle (i.e., comprising a functional complex), it seems reasonable that they could have been recruited independently relatively easily in gorillas and chimpanzees, thus increasing the likelihood of homoplasy. If, however, there is no evidence for a knuckle-walking complex, then it seems less likely that chimpanzees and gorillas would have evolved knuckle-walking independently. Results indicate that chimpanzees and gorillas are not characterized by high magnitudes of integration or unique patterns of integration that distinguish them from non-knuckle-walking taxa. This does not support the hypothesis of a knuckle-walking complex, nor does it support the contention that knuckle-walking could have been easily evolved independently in chimpanzees and gorillas. Implications for trait analysis and the evolution of bipedalism are discussed, as are recent analyses supporting the independent origins of knuckle-walking. PMID:20409573

Williams, Scott A

2010-04-20

370

Foot Placement and Velocity Control in Smooth Bipedal Walking  

Microsoft Academic Search

For a walking robot to negotiate rough terrain itmust adjust its step length to hit suitable footholdswhile simultaneously regulating its forward speed. Thispaper develops an algorithm to achieve these aims fora planar dynamic biped in the context of smooth exchangeof support. The basis of the algorithm is anasymmetric gait to adjust walking velocity combinedwith a set of conditions on the

Eric R. Dunn

1998-01-01

371

Modular Architecture for Humanoid Walking Pattern Prototyping and Experiments  

Microsoft Academic Search

In this paper we describe the use of design patterns as a basis for creating a Humanoid Walking Pattern Generator Software having a modular architecture. This architecture made possible the rapid porting of several novel walking algorithms on a full size humanoid robot HRP-2. The body of work currently available allows extracting a general software architecture usable with inter-exchange between

Olivier Stasse; Björn Verrelst; Pierre-Brice Wieber; Bram Vanderborght; Paul Evrard; Abderrahmane Kheddar; Kazuhito Yokoi

2008-01-01

372

The Occupation of City-Walking: Crossing the Invisible Line  

Microsoft Academic Search

Purpose: In this pilot study, occupational science students participated in a walk around a major Health Sciences Center Campus. The purpose of this action research project was to introduce students in occupational science to the inter-city community through the occupation of walking as an introductory method of being exposed to cultural variation. The overarching question was: In an inner-city setting,

RoyeenCharlotte; Cassini Teresa OTRL; BarneyKaren; Matin Royeen

2009-01-01

373

Quadruped walking robots at Tokyo Institute of Technology  

Microsoft Academic Search

In this article, the design principle of the leg driving mechanism to minimize energy loss and maximize output power is discussed. We will also introduce the gait control methods implemented in our previous quadruped walking robots. Finally, we will survey most of the prototype models of our quadruped walking robots.

Shigeo Hirose; Yasushi Fukuda; Kan Yoneda; Akihiko Nagakubo; Hideyuki Tsukagoshi; Keisuke Arikawa; Gen Endo; Takahiro Doi; Ryuichi Hodoshima

2009-01-01

374

RANDOM WALKS ON GROUPS: STRONG UNIFORM TIME APPROACH  

Microsoft Academic Search

mixing. We show that the total separation is the mean of the best possible strong uniform time. We prove various bounds on the total separation, find connections with hitting times and establish relations between total separations under several natural operations on walks on groups, such as rescaling of the walk, taking direct and wreath product of groups. In this work

Igor Pak

375

Elastic coupling of limb joints enables faster bipedal walking.  

PubMed

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

Dean, J C; Kuo, A D

2008-10-28

376

Random walks with infinite spatial and temporal moments  

Microsoft Academic Search

The continuous-time random walk of Montroll and Weiss has been modified by Scher and Lax to include a coupled spatial-temporal memory. We treat novel cases for the random walk and the corresponding generalized master equation when combinations of both spatial, and temporal moments of the memory are infinite. The asymptotic properties of the probability distribution for being at any lattice

Michael F. Shlesinger; Joseph Klafter; Y. M. Wong

1982-01-01

377

Walk This Way! Taking Steps for Pedestrian Safety  

MedlinePLUS

... your visibility at night by wearing retro-reflective clothing and carrying flashlights. Walking is good for your health, and it's good for the environment too. But before you head out on foot for a stroll, power walk, or errand, there are important safety tips ...

378

Numerical and Analytic Studies of Random-Walk Models  

Microsoft Academic Search

We begin by recapitulating the universality approach to problems associated with critical systems, and discussing the role that random-walk models play in the study of phase transitions and critical phenomena. As our first numerical simulation project, we perform high-precision Monte Carlo calculations for the exponents of the intersection probability of pairs and triplets of ordinary random walks in 2 dimensions,

Bin Li

1992-01-01

379

Measurement of lumbar spine kinematics in incline treadmill walking  

Microsoft Academic Search

A study was undertaken to analyse and compare the pelvic (S1) and the trunk (T12) oscillations during level and uphill walking and to provide kinematic baseline data of the lumbar region in incline walking for future comparisons with pathological gait patterns. An ultrasonic movement analysis device (Zebris® CMS 50) was used to obtain three-dimensional kinematic data for the pelvis and

L. Vogt; W. Banzer

1999-01-01

380

Adaptive control of biped robot walking on an inclined plane  

Microsoft Academic Search

The problem of walk control of a biped robot is considered. The inertial robot parameters are assumed unknown and control actions are applied only twice during one step. The control aim is for robot walking with a given average speed without falls and jumps; a desired trajectory is not given. A two-level control method is designed and theoretically justified. The

Sergei V. GUSEV; Serge L. SHISHKIN

1996-01-01

381

Incline, speed, and distance assessment during unconstrained walking.  

PubMed

Body accelerations during human walking were recorded by a portable measuring device. A new method for parameterizing body accelerations and finding the pattern of walking is outlined. Two neural networks were designed to recognize each pattern and estimate the speed and incline of walking. Six subjects performed treadmill walking followed by self-paced walking on an outdoor test circuit involving roads of various inclines. The neural networks were first "trained" by known patterns of treadmill walking. Then the inclines, the speeds, and the distance covered during overground walking (outdoor circuit) were estimated. The results show a good agreement between actual and predicted variables. The standard deviation of estimated incline was less than 2.6% and the maximum of the coefficient of variation of speed estimation is 6%. To the best of our knowledge, these results constitute the first assessment of speed, incline and distance covered during level and slope walking and offer investigators a new tool for assessing levels of outdoor physical activity. PMID:7723646

Aminian, K; Robert, P; Jéquier, E; Schutz, Y

1995-02-01

382

Wearable sensor systems in biomechanics: assessment of unrestrained walking features  

Microsoft Academic Search

A wearable sensor system is proposed to determine several walking features. including stride length, cadence, walking speed, incline. The sensor system is composed of an inertial measurement unit (IMU) mounted on the foot instep and a biaxial accelerometer mounted on the waist. The IMU integrates a biaxial accelerometer and a rate gyroscope. Both the foot gyroscope and the waist accelerometer

Angelo M. Sabatini

2004-01-01

383

Towards active actuated natural walking humanoid robot legs  

Microsoft Academic Search

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

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

2011-01-01

384

Compliant leg behaviour explains basic dynamics of walking and running  

PubMed Central

The basic mechanics of human locomotion are associated with vaulting over stiff legs in walking and rebounding on compliant legs in running. However, while rebounding legs well explain the stance dynamics of running, stiff legs cannot reproduce that of walking. With a simple bipedal spring–mass model, we show that not stiff but compliant legs are essential to obtain the basic walking mechanics; incorporating the double support as an essential part of the walking motion, the model reproduces the characteristic stance dynamics that result in the observed small vertical oscillation of the body and the observed out-of-phase changes in forward kinetic and gravitational potential energies. Exploring the parameter space of this model, we further show that it not only combines the basic dynamics of walking and running in one mechanical system, but also reveals these gaits to be just two out of the many solutions to legged locomotion offered by compliant leg behaviour and accessed by energy or speed.

Geyer, Hartmut; Seyfarth, Andre; Blickhan, Reinhard

2006-01-01

385

Radar walk detection in the apartments of elderly.  

PubMed

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

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

2012-01-01

386

Field testing of physiological responses associated with Nordic Walking.  

PubMed

This study compared the physiological responses (oxygen consumption and energy expenditure) of Nordic Walking to regular walking under field-testing conditions. Eleven women (M age = 27.1 years, SD = 6.4) and 11 men (M age = 33.8 years, SD = 9.0) walked 1,600 m with and without walking poles on a level, 200-m track. For women, Nordic Walking resulted in increased oxygen consumption (M = 14.9 ml x kg(-1) x min(-1), SD = 3.2 vs. M = 1 7.9 ml x kg(-1) min(-1), SD = 3.5; p < .001), caloric expenditure (M = 4.6 kcal x min(-1), SD = 1.2 vs. M = 5.4 kcal x min(-1), SD = 1.2; p < .001), and heart rate (M = 113.7 bpm, SD = 12.0 vs. M = 118.7 bpm, SD = 14.8; p < .05) compared to regular walking. For men, Nordic Walking resulted in increased oxygen consumption (M = 12.8 ml x kg(-1) min(-1), SD = 1.8 vs. M = 15.5, SD =3.4 ml x kg(-1) min(-1); p < .01), caloric expenditure (M = 5.7 kcal x min(-1), SD = 1.3 vs. M = 6.9 kcal x min(-1), SD = 1.8; p < .001), and heart rate (M = 101.6 bpm, SD = 12.0 bpm vs. M = 109.8 bpm, SD = 14.7; p < .01) compared to regular walking. Nordic Walking, examined in the field, results in a significant increase in oxygen use and caloric expenditure compared to regular walking, without significantly increasing perceived exertion. PMID:12230336

Church, Timothy S; Earnest, Conrad P; Morss, Gina M

2002-09-01

387

Influence of non-level walking on pedometer accuracy.  

PubMed

The YAMAX Digiwalker pedometer has been previously confirmed as a valid and reliable monitor during level walking, however, little is known about its accuracy during non-level walking activities or between genders. Subsequently, this study examined the influence of non-level walking and gender on pedometer accuracy. Forty-six healthy adults completed 3-min bouts of treadmill walking at their normal walking pace during 11 inclines (0-10%) while another 123 healthy adults completed walking up and down 47 stairs. During walking, participants wore a YAMAX Digiwalker SW-700 pedometer with the number of steps taken and registered by the pedometer recorded. Pedometer difference (steps registered-steps taken), net error (% of steps taken), absolute error (absolute % of steps taken) and gender were examined by repeated measures two-way ANOVA and Tukey's post hoc tests. During incline walking, pedometer accuracy indices were similar between inclines and gender except for a significantly greater step difference (-7+/-5 steps vs. 1+/-4 steps) and net error (-2.4+/-1.8% for 9% vs. 0.4+/-1.2% for 2%). Step difference and net error were significantly greater during stair descent compared to stair ascent while absolute error was significantly greater during stair ascent compared to stair descent. The current study demonstrated that the YAMAX Digiwalker SW-700 pedometer exhibited good accuracy during incline walking up to 10% while it overestimated steps taken during stair ascent/descent with greater overestimation during stair descent. Stair walking activity should be documented in field studies as the YAMAX Digiwalker SW-700 pedometer overestimates this activity type. PMID:18356103

Leicht, Anthony S; Crowther, Robert G

2008-03-19

388

Effect of whole-body vibration exercise and muscle strengthening, balance, and walking exercises on walking ability in the elderly  

Microsoft Academic Search

The present study was conducted to determine the beneficial effect of whole- body vibration (WBV) exercise in addition to muscle strengthening, balance, and walking exercises on the walking ability in the elderly. Sixty-seven elderly participants were divided into two groups; the WBV exercise plus routine exercises group (n=40) and the routine ex- ercises alone group (n=27). WBV exercise was performed

Kazuhiro Kawanabe; Akira Kawashima; Issei Sashimoto; Tsuyoshi Takeda; Yoshihiro Sato; Jun Iwamoto

2007-01-01

389

WalkSafe: a pedestrian safety app for mobile phone users who walk and talk while crossing roads  

Microsoft Academic Search

Research in social science has shown that mobile phone conversations distract users, presenting a significant impact to pedestrian safety; for example, a mobile phone user deep in conversation while crossing a street is generally more at risk than other pedestrians not engaged in such behavior. We propose WalkSafe, an Android smartphone application that aids people that walk and talk, improving

Tianyu Wang; Giuseppe Cardone; Antonio Corradi; Lorenzo Torresani; Andrew T. Campbell

2012-01-01

390

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

PubMed

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

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

2010-06-01

391

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

Microsoft Academic Search

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

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

392

Adaptation of the walking pattern to uphill walking in normal and spinal-cord injured subjects  

Microsoft Academic Search

Lower-limb movements and muscle-activity patterns were assessed from seven normal and seven ambulatory subjects with incomplete\\u000a spinal-cord injury (SCI) during level and uphill treadmill walking (5, 10 and 15°). Increasing the treadmill grade from 0°\\u000a to 15° induced an increasingly flexed posture of the hip, knee and ankle during initial contact in all normal subjects, resulting\\u000a in a larger excursion

Alain Leroux; Joyce Fung; Hugues Barbeau

1999-01-01

393

Excursion set theory for correlated random walks  

NASA Astrophysics Data System (ADS)

We present a new method to compute the first crossing distribution in excursion set theory for the case of correlated random walks. We use a combination of the path integral formalism of Maggiore & Riotto, and the integral equation solution of Zhang & Hui and Benson et al. to find a numerically and convenient algorithm to derive the first crossing distribution. We apply this methodology to the specific case of a Gaussian random density field filtered with a Gaussian smoothing function. By comparing our solutions to results from Monte Carlo calculations of the first crossing distribution we demonstrate that approximately it is in good agreement with exact solution for certain barriers, and at large masses. Our approach is quite general, and can be adapted to other smoothing functions and barrier function and also to non-Gaussian density fields.

Farahi, Arya; Benson, Andrew J.

2013-08-01

394

Quantum random walk: Effect of quenching  

NASA Astrophysics Data System (ADS)

We study the effect of quenching on a discrete quantum random walk by removing a detector placed at a position xD abruptly at time tR from its path. The results show that this may lead to an enhancement of the occurrence probability at xD provided the time of removal tR

Goswami, Sanchari; Sen, Parongama

2012-08-01

395

Two-dimensional Quantum Random Walk  

NASA Astrophysics Data System (ADS)

We analyze several families of two-dimensional quantum random walks. The feasible region (the region where probabilities do not decay exponentially with time) grows linearly with time, as is the case with one-dimensional QRW. The limiting shape of the feasible region is, however, quite different. The limit region turns out to be an algebraic set, which we characterize as the rational image of a compact algebraic variety. We also compute the probability profile within the limit region, which is essentially a negative power of the Gaussian curvature of the same algebraic variety. Our methods are based on analysis of the space-time generating function, following the methods of Pemantle and Wilson (J. Comb. Theory, Ser. A 97(1):129-161, 2002).

Baryshnikov, Yuliy; Brady, Wil; Bressler, Andrew; Pemantle, Robin

2011-01-01

396

Two-dimensional Quantum Random Walk  

NASA Astrophysics Data System (ADS)

We analyze several families of two-dimensional quantum random walks. The feasible region (the region where probabilities do not decay exponentially with time) grows linearly with time, as is the case with one-dimensional QRW. The limiting shape of the feasible region is, however, quite different. The limit region turns out to be an algebraic set, which we characterize as the rational image of a compact algebraic variety. We also compute the probability profile within the limit region, which is essentially a negative power of the Gaussian curvature of the same algebraic variety. Our methods are based on analysis of the space-time generating function, following the methods of Pemantle and Wilson (J. Comb. Theory, Ser. A 97(1):129-161, 2002).

Baryshnikov, Yuliy; Brady, Wil; Bressler, Andrew; Pemantle, Robin

2010-12-01

397

Walks with optimal reward on metric spaces  

NASA Astrophysics Data System (ADS)

Let (M, d) be a complete metric space and suppose that there are given finitely many contractions ??:M? M and Lipschitz maps \\varphi_{\\rho}:M\\rightarrow{\\Bbb R} (? = 1, ..., r). We consider 'walks' of length m with a given starting point x0 in M. They are defined as follows: one chooses a sequence (??)?=1,..., m of length m in {1, ..., r}, and this choice induces the 'walk' \\[ \\begin{eqnarray*}\\fl x_{0},\\ x_{1}:=\\Gamma_{\\rho_{1}}(x_{0}),\\tqs x_{2}:=\\Gamma_{\\rho_{2}}(x_{1}), \\ldots,\\tqs x_{m}:=\\Gamma_{\\rho_{m}}(x_{m-1}).\\end{eqnarray*} \\] Associated with x1, ..., xm is the 'reward' \\[ \\begin{equation*}\\varphi_{\\rho_{1}}(x_{0})+\\varphi_{\\rho_{2}}(x_{1})+\\cdots+\\varphi_{\\rho_{m}}(x_{m-1}).\\end{equation*} \\] We denote by R^{\\max}_{x_{0}}(m) the maximal possible reward. The aim of this paper is to investigate the behaviour of the sequence (R^{\\max}_{x_{0}}(m)) for large m. It will be shown that the growth is nearly linear: there is a constant ? (which does not depend on x0) such that R^{\\max}_{x_{0}}(m)/m tends to ?. However, an explicit calculation of ? might be hard. The complexity depends on the fractal dimension of the smallest nonempty compact subset of M which is invariant with respect to all ??. In the case of finite M one can say much more. Then—after a suitable rescaling—the sequence (R^{\\max}_{x_{0}}(m)) is periodic where the length of the period can be described in terms of the length of certain cycles of a graph associated with M. The motivation to study this problem came from a variant of Parrondo's paradox from probability theory: what is the optimal choice of games if a great number of players is involved?

Behrends, Ehrhard

2006-03-01

398

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

PubMed

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

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

2011-02-01

399

Predicting the metabolic cost of incline walking from muscle activity and walking mechanics.  

PubMed

The goal of this study was to identify which muscle activation patterns and gait features best predict the metabolic cost of inclined walking. We measured muscle activation patterns, joint kinematics and kinetics, and metabolic cost in sixteen subjects during treadmill walking at inclines of 0%, 5%, and 10%. Multivariate regression models were developed to predict the net metabolic cost from selected groups of the measured variables. A linear regression model including incline and the squared integrated electromyographic signals of the soleus and vastus lateralis explained 96% of the variance in metabolic cost, suggesting that the activation patterns of these large muscles have a high predictive value for metabolic cost. A regression model including only the peak knee flexion angle during stance phase, peak knee extension moment, peak ankle plantarflexion moment, and peak hip flexion moment explained 89% of the variance in metabolic cost; this finding indicates that kinematics and kinetics alone can predict metabolic cost during incline walking. The ability of these models to predict metabolic cost from muscle activation patterns and gait features points the way toward future work aimed at predicting metabolic cost when gait is altered by changes in neuromuscular control or the use of an assistive technology. PMID:22578744

Silder, Amy; Besier, Thor; Delp, Scott L

2012-05-11

400

Changes in corticospinal excitability following adaptive modification to human walking.  

PubMed

Locomotor adaptations to a novel environment can be measured through changes in muscle activity patterns and lower limb kinematics. The location and mechanisms underlying these adaptive changes are unknown. The purposes of the current study were (1) to determine whether corticospinal tract (CST) excitability is altered by resisted walking and (2) to ascertain whether changes in cortical excitability are muscle specific. Forty healthy participants walked with a robotic gait device (Lokomat) that applied a velocity-dependent resistance against hip and knee movements during walking. CST excitability was assessed by quantifying motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation immediately before and after baseline and resisted walking. MEPs were measured in either the biceps femoris (BF) or the rectus femoris (RF). Recruitment curves were collected by stimulating in 5 % increments from 105 to 145 % of active motor threshold. Results demonstrated a significant increase in MEP amplitude in the BF following baseline walking in the Lokomat. The RF did not demonstrate these changes. There was no further change in MEP size following resisted walking in either muscle group. These results suggest that locomotion increases CST excitability in a muscle-specific fashion. As such, it may be important for determining how to enhance the central nervous system's ability to integrate adaptive strategies during walking. PMID:23494384

Zabukovec, J R; Boyd, L A; Linsdell, M A; Lam, T

2013-03-15

401

Simulation Studies of Bipedal Walking on the Moon and Mars  

NASA Astrophysics Data System (ADS)

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

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

402

Quantum walk on a line with two entangled particles  

SciTech Connect

We introduce the concept of a quantum walk with two particles and study it for the case of a discrete time walk on a line. A quantum walk with more than one particle may contain entanglement, thus offering a resource unavailable in the classical scenario and which can present interesting modifications on quantum walks with single particles. In this work, we show both numerically and analytically how the entanglement and the relative phase between the states describing the coin degree of freedom of each particle will influence the evolution of the quantum walk. In particular, the probability to find at least one particle in a certain position after N steps of the walk, as well as the average distance and the squared distance between the two particles, can be larger or smaller than the case of two unentangled particles, depending on the initial conditions we choose. This resource can then be tuned according to our needs to modify the features of a quantum walk. Experimental implementations are briefly discussed.

Omar, Y.; Paunkovic, N.; Sheridan, L.; Bose, S. [SQIG, Instituto de Telecomunicacoes and CEMAPRE, ISEG, Universidade Tecnica de Lisboa, P-1200-781 Lisbon (Portugal); SQIG, Instituto de Telecomunicacoes and Instituto Superior Tecnico, P-1049-001 Lisbon (Portugal); Institute for Quantum Computing, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G5 (Canada); Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2006-10-15

403

Behavior Change Techniques Used to Promote Walking and Cycling  

PubMed Central

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.

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

2013-01-01

404

Visual Control of Foot Placement When Walking Over Complex Terrain.  

PubMed

The aim of this study was to investigate the role of visual information in the control of walking over complex terrain with irregularly spaced obstacles. We developed an experimental paradigm to measure how far along the future path people need to see in order to maintain forward progress and avoid stepping on obstacles. Participants walked over an array of randomly distributed virtual obstacles that were projected onto the floor by an LCD projector while their movements were tracked by a full-body motion capture system. Walking behavior in a full-vision control condition was compared with behavior in a number of other visibility conditions in which obstacles did not appear until they fell within a window of visibility centered on the moving observer. Collisions with obstacles were more frequent and, for some participants, walking speed was slower when the visibility window constrained vision to less than two step lengths ahead. When window sizes were greater than two step lengths, the frequency of collisions and walking speed were weakly affected or unaffected. We conclude that visual information from at least two step lengths ahead is needed to guide foot placement when walking over complex terrain. When placed in the context of recent research on the biomechanics of walking, the findings suggest that two step lengths of visual information may be needed because it allows walkers to exploit the passive mechanical forces inherent to bipedal locomotion, thereby avoiding obstacles while maximizing energetic efficiency. (PsycINFO Database Record (c) 2013 APA, all rights reserved). PMID:23750964

Matthis, Jonathan S; Fajen, Brett R

2013-06-10

405

Unique characteristics of motor adaptation during walking in young children  

PubMed Central

Children show precocious ability in the learning of languages; is this the case with motor learning? We used split-belt walking to probe motor adaptation (a form of motor learning) in children. Data from 27 children (ages 8–36 mo) were compared with those from 10 adults. Children walked with the treadmill belts at the same speed (tied belt), followed by walking with the belts moving at different speeds (split belt) for 8–10 min, followed again by tied-belt walking (postsplit). Initial asymmetries in temporal coordination (i.e., double support time) induced by split-belt walking were slowly reduced, with most children showing an aftereffect (i.e., asymmetry in the opposite direction to the initial) in the early postsplit period, indicative of learning. In contrast, asymmetries in spatial coordination (i.e., center of oscillation) persisted during split-belt walking and no aftereffect was seen. Step length, a measure of both spatial and temporal coordination, showed intermediate effects. The time course of learning in double support and step length was slower in children than in adults. Moreover, there was a significant negative correlation between the size of the initial asymmetry during early split-belt walking (called error) and the aftereffect for step length. Hence, children may have more difficulty learning when the errors are large. The findings further suggest that the mechanisms controlling temporal and spatial adaptation are different and mature at different times.

Musselman, Kristin E.; Patrick, Susan K.; Vasudevan, Erin V. L.; Bastian, Amy J.

2011-01-01

406

Biomechanics of slow running and walking with a rocker shoe.  

PubMed

Evidence suggests a link between the loading of the Achilles tendon and the magnitude of the ankle internal plantar flexion moment during late stance of gait, which is clinically relevant in the management of Achilles tendinopathy. Some studies showed that rocker shoes can reduce the ankle internal plantar flexion moment. However, the existing evidence is not conclusive and focused on walking and scarce in running. Sixteen healthy runners participated in this study. Lower extremity kinetics, kinematics and electromyographic (EMG) signals of triceps surae and tibialis anterior were quantified for two types of shoes during running and walking. The peak ankle plantar flexion moment was reduced significantly in late stance of running (0.27Nm/kg; p<0.001) and walking (0.24Nm/kg; p<0.001) with the rocker shoe compared to standard shoe. The ankle power generation and plantar flexion moment impulse were also reduced significantly when running and walking with the rocker shoe (p<0.001). No significant changes in the knee and hip moments were found in running and walking. A significant delay of the EMG peak, approximately 2% (p<0.001), was present in the triceps surae when walking with rocker shoes. There were no significant changes in the EMG peak amplitude of triceps surae in running and walking. The peak amplitude of tibialis anterior was significantly increased (64.7?V, p<0.001) when walking with rocker shoes. The findings show that rocker shoes reduce the ankle plantar flexion moment during the late stance phase of running and walking in healthy people. PMID:23770233

Sobhani, Sobhan; Hijmans, Juha; van den Heuvel, Edwin; Zwerver, Johannes; Dekker, Rienk; Postema, Klaas

2013-06-14

407

Discrete single-photon quantum walks with tunable decoherence.  

PubMed

Quantum walks have a host of applications, ranging from quantum computing to the simulation of biological systems. We present an intrinsically stable, deterministic implementation of discrete quantum walks with single photons in space. The number of optical elements required scales linearly with the number of steps. We measure walks with up to 6 steps and explore the quantum-to-classical transition by introducing tunable decoherence. Finally, we also investigate the effect of absorbing boundaries and show that decoherence significantly affects the probability of absorption. PMID:20481989

Broome, M A; Fedrizzi, A; Lanyon, B P; Kassal, I; Aspuru-Guzik, A; White, A G

2010-04-16

408

Decoherence in a one-dimensional quantum walk  

SciTech Connect

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.

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

409

Better Walking Performance in Older Children With Cerebral Palsy  

Microsoft Academic Search

Background  Children with cerebral palsy (CP) often walk with a slower speed and a higher energy cost. Their walking performance and choice\\u000a of mobility method may vary in different environments. Independent mobility is important for activity and participation.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We described walking performance at different distances and environments in relation to gross motor function, CP subtype,\\u000a and age.\\u000a \\u000a \\u000a \\u000a \\u000a Patients and Methods  We performed

Elisabet Rodby-Bousquet RPT; Gunnar Hägglund

410

A New Family of Solvable Pearson-Dirichlet Random Walks  

NASA Astrophysics Data System (ADS)

An n-step Pearson-Gamma random walk in ? d starts at the origin and consists of n independent steps with gamma distributed lengths and uniform orientations. The gamma distribution of each step length has a shape parameter q>0. Constrained random walks of n steps in ? d are obtained from the latter walks by imposing that the sum of the step lengths is equal to a fixed value. Simple closed-form expressions were obtained in particular for the distribution of the endpoint of such constrained walks for any d? d 0 and any n?2 when q is either q = d/2 - 1 ( d 0=3) or q= d-1 ( d 0=2) (Le Caër in J. Stat. Phys. 140:728-751, 2010). When the total walk length is chosen, without loss of generality, to be equal to 1, then the constrained step lengths have a Dirichlet distribution whose parameters are all equal to q and the associated walk is thus named a Pearson-Dirichlet random walk. The density of the endpoint position of a n-step planar walk of this type ( n?2), with q= d=2, was shown recently to be a weighted mixture of 1+ floor( n/2) endpoint densities of planar Pearson-Dirichlet walks with q=1 (Beghin and Orsingher in Stochastics 82:201-229, 2010). The previous result is generalized to any walk space dimension and any number of steps n?2 when the parameter of the Pearson-Dirichlet random walk is q= d>1. We rely on the connection between an unconstrained random walk and a constrained one, which have both the same n and the same q= d, to obtain a closed-form expression of the endpoint density. The latter is a weighted mixture of 1+ floor( n/2) densities with simple forms, equivalently expressed as a product of a power and a Gauss hypergeometric function. The weights are products of factors which depends both on d and n and Bessel numbers independent of d.

Le Caër, Gérard

2011-07-01

411

Decoherence in a one-dimensional quantum walk  

NASA Astrophysics Data System (ADS)

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 [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.

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

2010-03-01

412

Discrete-time quantum walks: Continuous limit and symmetries  

SciTech Connect

The continuous limit of one-dimensional discrete-time quantum walks with time-and space-dependent coefficients is investigated. A given quantum walk does not generally admit a continuous limit but some families (1-jets) of quantum walks do. All families (1-jets) admitting a continuous limit are identified. The continuous limit is described by a Dirac-like equation or, alternately, a couple of Klein-Gordon equations. Variational principles leading to these equations are also discussed, together with local invariance properties.

Molfetta, G. di; Debbasch, F. [Universite Paris 6, ERGA-LERMA, UMR 8112, 3, rue Galilee, F-94200 Ivry (France)

2012-12-15

413

Limit theorems for quantum walks associated with Hadamard matrices  

SciTech Connect

We study a one-parameter family of discrete-time quantum walk models on Z and Z{sup 2} associated with the Hadamard walk. Weak convergence in the long-time limit of all moments of the walker's pseudovelocity on Z and Z{sup 2} is proved. Symmetrization on Z and Z{sup 2} is theoretically investigated, leading to the resolution of the Konno-Namiki-Soshi conjecture in the special case of symmetrization of the unbiased Hadamard walk on Z. A necessary condition for the existence of a phenomenon known as localization is given.

Ampadu, Clement [31 Carrolton Road, Boston, MA 02132 (United States)

2011-07-15

414

The development of an estimation model for energy expenditure during water walking by acceleration and walking speed.  

PubMed

OBJECTIVES: The aim of this study was to develop an estimation equation for energy expenditure during water walking based on the acceleration and walking speed. DESIGN: Cross-validation study. METHODS: Fifty participants, males (n=29, age: 27-73) and females (n=21, age: 33-70) volunteered for this study. Based on their physical condition water walking was conducted at three self-selected walking speeds from a range of: 20, 25, 30, 35 and 40m/min. Energy expenditure during each trial was calculated. During water walking, an accelerometer was attached to the occipital region and recorded three-dimensional accelerations at 100Hz. A stopwatch was used for timing the participant's walking speed. The estimation model for energy expenditure included three components; (i) resting metabolic rate, (ii) internal energy expenditure for moving participants' body, and (iii) external energy expenditure due to water drag force. RESULTS: When comparing the measured and estimated energy expenditure with the acceleration data being the third component of the estimation model, high correlation coefficients were found in both male (r=0.73) and female (r=0.77) groups. When walking speeds were applied to the third component of the model, higher correlation coefficients were found (r=0.82 in male and r=0.88 in female). Good agreements of the developed estimation model were found in both methods, regardless of gender. CONCLUSION: This study developed a valid estimation model for energy expenditure during water walking by using head acceleration and walking speed. PMID:23499496

Kaneda, Koichi; Ohgi, Yuji; Tanaka, Chiaki; Burkett, Brendan

2013-03-14

415

Walking Skill Can Be Assessed in Older Adults: Validity of the Figure-of-8 Walk Test  

PubMed Central

Background The Figure-of-8 Walk Test (F8W) involves straight and curved paths and was designed to represent walking skill in everyday life. Objective The purposes of this study were to validate the measure in older adults with walking difficulties and to explore correlates of the curved-path walking measure not represented by a straight-path walking measure. Design Fifty-one community-dwelling older adults with mobility disability participated in 2 baseline visits as part of an intervention study. Methods The F8W time, steps, and smoothness and measures of gait (gait speed, modified Gait Abnormality Rating Scale [GARS-M]), physical function (Late Life Function and Disabilities Index [LLFDI], Survey of Activities and Fear of Falling in the Elderly [SAFFE], Gait Efficacy Scale [GES], Physical Performance Test [PPT], and fall history), and movement control and planning (gait variability, Trail Making Test B [Trails B]) were recorded in each test session. Bivariate correlations for the F8W with each variable were conducted to examine concurrent and construct validity. Adjusted linear regression analyses were performed to explore the variance in mobility explained by F8W independent of gait speed. Results Figure-of-8 Walk Test time correlated with gait (gait speed, r=?.570; GARS-M, r=.281), physical function (LLFDI function, r=?.469; SAFFE restriction subscale, r=.370; PPT, r=?.353), confidence in walking (GES, r=?.468), and movement control (step length coefficient of variation, r=.279; step width coefficient of variation, r=?.277; Trails B, r=.351). Figure-of-8 Walk Test steps correlated with step width variability (r=?.339) and was related to fear of falling (t=?2.50). All correlations were significant (P<.05). Limitations This pilot study had a small sample size, and further research is needed. Conclusions The F8W is a valid measure of walking skill among older adults with mobility disability and may provide information complementary to gait speed.

Brach, Jennifer S.; Piva, Sara R.; VanSwearingen, Jessie M.

2010-01-01

416

Predictors of 6-minute walk test and 12-minute walk/run test in obese children and adolescents.  

PubMed

The purpose of this study was to identify predictors of the distance achieved during a 6-minute walk test and a 12-minute walk/run test (Cooper test) in obese children and adolescents and to evaluate the influence of a residential treatment on the association of these predictors with the distance. A search of the Revalidation Centre Zeepreventorium (De Haan, Belgium) medical records database of all children and adolescents (age 10 to 18 yrs) treated for obesity between September 2003 and February 2006, revealed 65 charts with all relevant data (anthropometrical, maximal graded exercise, lung function, 6-minute walk test and 12-minute walk/run test) at admission as well as after 3 months treatment. The multidisciplinary treatment has a positive influence on anthropometrical variables, endurance capacity, vital capacity, and residual volume (p < 0.05). The distance covered during the 6-minute walk test and the 12-minute walk/run test is correlated with all anthropometrical data and peak VO2 (p < 0.05). After 3 months of treatment, bivariate correlation was stronger for almost every parameter compared to admission. Following a stepwise regression, BMI z-score is a dominant predictor of both field tests at admission and after 3 months treatment. VO2peak contributes only significantly in the 12-minute walk/run test at admission. Conclusion: In obese children and adolescents BMI z-score is the most dominant predictor of the variability in performances on the 6-minute walk test and the 12-minute walk/run test at admission as well as after 3 months of treatment. PMID:17726615

Calders, Patrick; Deforche, Benedicte; Verschelde, Sabine; Bouckaert, Jacques; Chevalier, Frederic; Bassle, Eddy; Tanghe, Ann; De Bode, Patrick; Franckx, Hilde

2007-08-29

417

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

ERIC Educational Resources Information Center

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

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

2009-01-01

418

Do Humans Optimally Exploit Redundancy to Control Step Variability in Walking?  

Microsoft Academic Search

It is widely accepted that humans and animals minimize energetic cost while walking. While such principles predict average behavior, they do not explain the variability observed in walking. For robust performance, walking movements must adapt at each step, not just on average. Here, we propose an analytical framework that reconciles issues of optimality, redundancy, and stochasticity. For human treadmill walking,

Jonathan B. Dingwell; Joby John; Joseph P. Cusumano

2010-01-01

419

Development of a biped walking robot compensating for three-axis moment by trunk motion  

Microsoft Academic Search

The authors have been using the ZMP (zero moment point) as a criterion to distinguish the stability of walking for a biped walking robot which has a trunk. The authors introduce a control method of dynamic biped walking for a biped walking robot to compensate for the three-axis (pitch, roll and yaw-axis) moment on an arbitrary planned ZMP by trunk

Jin-ichi YAMAGUCHI; Atsuo TAKANISHI; I. Kato

1993-01-01

420

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

ERIC Educational Resources Information Center

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

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

2009-01-01

421

Biped Gait Generation and Control Based on a Unified Property of Passive Dynamic Walking  

Microsoft Academic Search

Principal mechanisms of passive dynamic walking are studied from the mechanical energy point of view, and novel gait generation and control methods based on passive dynamic walking are proposed. First, a unified property of passive dynamic walking is derived, which shows that the walking system's mechanical energy increases proportionally with respect to the position of the system's center of mass.

Fumihiko Asano; Zhi-Wei Luo; Masaki Yamakita

2005-01-01

422

Physical Performance in Peripheral Arterial Disease: A Slower Rate of Decline in Patients Who Walk More  

Microsoft Academic Search

Background: Exercise rehabilitation programs increase treadmill walking performance in patients with peripheral arterial disease (PAD) and intermittent claudication. However, it is unknown whether patients with PAD who walk for exercise regularly have less functional decline than those with less walking activity. Objective: To determine whether patients with PAD who report that they walk for exercise 3 or more times per

Mary McGrae McDermott; Kiang Liu; Luigi Ferrucci; Michael H. Criqui; Philip Greenland; Jack M. Guralnik; Lu Tian; Joseph R. Schneider; William H. Pearce; Jin Tan; Gary J. Martin

2006-01-01

423

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

ERIC Educational Resources Information Center

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

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

2009-01-01

424

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

PubMed

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

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

2005-09-01

425

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

ERIC Educational Resources Information Center

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

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

2009-01-01

426

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

PubMed

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

Hubel, Tatjana Y; Usherwood, James R

2013-01-16

427

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

Microsoft Academic Search

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

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

2006-01-01

428

Group velocity of discrete-time quantum walks  

NASA Astrophysics Data System (ADS)

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.

Kempf, A.; Portugal, R.

2009-05-01

429

Gallery Walk Questions on Air Pressure and Wind  

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 Air Pressure and Wind. The questions are organized according to the ...

430

Random walks and search in time-varying networks.  

PubMed

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

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

2012-12-04

431

The Random Walk Theory of Stock Price Behavior.  

National Technical Information Service (NTIS)

The paper surveys the literature concerning the random walk theory of stock market price movement. Research is classified as either tests for independence of increments or attempts to define a probability distribution which approximates the price changes ...

J. R. Pickett

1970-01-01

432

Electron Avalanche Structure Determined by Random Walk Theory.  

National Technical Information Service (NTIS)

A self-consistent avalanche solution which accounts for collective long range Coulomb interactions as well as short range elastic and inelastic collisions between electrons and background atoms is made possible by a random walk technique. Results show tha...

G. W. Englert

1973-01-01

433

Two-particle quantum walks: Entanglement and graph isomorphism testing  

SciTech Connect

We study discrete-time quantum walks on the line and on general undirected graphs with two interacting or noninteracting particles. We introduce two simple interaction schemes and show that they both lead to a diverse range of probability distributions that depend on the correlations and relative phases between the initial coin states of the two particles. We investigate the characteristics of these quantum walks and the time evolution of the entanglement between the two particles from both separable and entangled initial states. We also test the capability of two-particle discrete-time quantum walks to distinguish nonisomorphic graphs. For strongly regular graphs, we show that noninteracting discrete-time quantum walks can distinguish some but not all nonisomorphic graphs with the same family parameters. By incorporating an interaction between the two particles, all nonisomorphic strongly regular graphs tested are successfully distinguished.

Berry, Scott D.; Wang, Jingbo B.

2011-04-15

434

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

435

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

436

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

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

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

437

72. View looking SE down pedestrian walking away from bridge ...  

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

72. View looking SE down pedestrian walking away from bridge towards Brooklyn. Jet Lowe, photographer, 1982. - Brooklyn Bridge, Spanning East River between Park Row, Manhattan and Sands Street, Brooklyn, New York, New York County, NY

438

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

439

9. Detail Showing top of Samson Post and Walking Beam ...  

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

9. Detail Showing top of Samson Post and Walking Beam Pivot, Looking East - David Renfrew Oil Rig, East side of Connoquenessing Creek, 0.4 mile North of confluence with Thorn Creek, Renfrew, Butler County, PA

440

4. Band Wheel and Walking Beam Mechanism, Including Remains of ...  

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

4. Band Wheel and Walking Beam Mechanism, Including Remains of Frame Belt House, Looking Southeast - David Renfrew Oil Rig, East side of Connoquenessing Creek, 0.4 mile North of confluence with Thorn Creek, Renfrew, Butler County, PA

441

A walking tour of the Calaveras fault in Hollister, California  

NSDL National Science Digital Library

This guide provides directions and descriptions for stops on a walking tour of the Calaveras Fault in Hollister, California. Maps and photos are used to show offset and damage to man-made structures caused by creep along the fault.

Dellinger, Joe

442

Gallery Walk Questions on the Hydrosphere and Cryosphere  

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 hydrosphere and cryosphere. The questions are organized according ...

443

Metabolic and Circulatory Responses to Walking and Jogging in Water.  

ERIC Educational Resources Information Center

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

Evans, Blanch W.

1978-01-01

444

34. VIEW FROM LITTLE ROUND TOP. NOW A PEDESTRIAN WALK, ...  

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

34. VIEW FROM LITTLE ROUND TOP. NOW A PEDESTRIAN WALK, THE ROAD ORIGINALLY PASSED ALONG THIS RIDGE. NOTE CONTEMPORARY INTERPRETIVE PANELS. VIEW WNW. - Gettysburg National Military Park Tour Roads, Gettysburg, Adams County, PA

445

Mixing times in quantum walks on two-dimensional grids  

SciTech Connect

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.

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

446

Fractional Brownian Motion:. Theory and Application to DNA Walk  

NASA Astrophysics Data System (ADS)

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

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

2001-09-01

447

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 ...

448

Gallery Walk Questions on Weathering and Mass Wasting  

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 weathering and mass wasting. The questions are organized according to ...

449

Improved noise immunity in a walk-through metal detector  

SciTech Connect

A new walk-through metal detector exhibits major improvements in noise rejection, discrimination between object types, and sensitivity to small objects. The talk includes a tutorial on the design and selection of metal detector sites.

Parks, S.I.; Horowitz, P.; Romine, P.

1987-07-01

450

Kinematics of walking in the hermit crab, Pagurus pollicarus.  

PubMed

Hermit crabs are decapod crustaceans that have adapted to life in gastropod shells. Among their adaptations are modifications to their thoracic appendages or pereopods. The 4th and 5th pairs are adapted for shell support; walking is performed with the 2nd and 3rd pereopods, with an alternation of diagonal pairs. During stance, the walking legs are rotated backwards in the pitch plane. Two patterns of walking were studied to compare them with walking patterns described for other decapods, a lateral gait, similar to that in many brachyurans, and a forward gait resembling macruran walking. Video sequences of free walking and restrained animals were used to obtain leg segment positions from which joint angles were calculated. Leading legs in a lateral walk generated a power stroke by flexion of MC and PD joints; CB angles often did not change during slow walks. Trailing legs exhibited extension of MC and PD with a slight levation of CB. The two joints, B/IM and CP, are aligned at 90° angles to CB, MC and PD, moving dorso-anteriorly during swing and ventro-posteriorly during stance. A forward step was more complex; during swing the leg was rotated forward (yaw) and vertically (pitch), due to the action of TC. At the beginning of stance, TC started to rotate posteriorly and laterally, CB was depressed, and MC flexed. As stance progressed and the leg was directed laterally, PD and MC extended, so that at the end of stance the dactyl tip was quite posterior. During walks of the animal out of its shell, the legs were extended more anterior-laterally and the animal often toppled over, indicating that during walking in a shell its weight stabilized the animal. An open chain kinematic model in which each segment was approximated as a rectangular solid, the dimensions of which were derived from measurements on animals, was developed to estimate the CM of the animal under different load conditions. CM was normally quite anterior; removal of the chelipeds shifted it caudally. Application of forces simulating the weight of the shell on the 5th pereopods moved CM just anterior to the thoracic-abdominal junction. However, lateral and vertical coordinates were not altered under these different load conditions. The interaction of the shell aperture with proximal leg joints and with the CM indicates that the oblique angles of the legs, due primarily to the rotation of the TC joints, is an adaptation that confers stability during walking. PMID:22321513

Chapple, William

2012-02-08

451

INTERACTIVELY RESPONSIVE ANIMATION OF HUMAN WALKING IN VIRTUAL ENVIRONMENTS  

Microsoft Academic Search

Abstract Computer animation of human ,locomotion ,has become ,popular in recent years because,of the ,desire to use ,human ,beings as synthetic ,actors in three-dimensional simulation environments. Researchers have proposed various motion control mechanisms tosimulate human-like figure locomotion. However, most of the animation systems based on these control mechanisms,are only suitable for animating human,walking on flat ground, without obstacles. For walking

Shih-kai Chung

2000-01-01

452

Simulating human walking on special terrain: up and down slopes  

Microsoft Academic Search

This paper presents a high-level approach of animating human walking on a special kind of terrain — slopes. The desired motion is conveniently specified by top-level parameters such as slope gradient, walking speed and step length. From these parameters, step constraints are derived to generate movement of the lower limbs by incorporating research results on human locomotion, such as “state-phase

Ling Li; Xiaoyan Liu

2000-01-01

453

Content Browsing by Walking in Real and Cyber Spaces  

Microsoft Academic Search

\\u000a “Walking” style operations for browsing content are described. This style is intuitive and enjoyable and enables the daily\\u000a use of digital content. We illustrate the concept with two examples. One is EnergyBrowser, a physical walking interface for\\u000a browsing Web pages. The other is a comparative 3D archive browser, which is for 3D archives. It automatically controls the\\u000a viewpoint in comparing

Satoshi Nakamura; Oh Sooyeon; Mitsuru Minakuchi; Rieko Kadobayashi

2005-01-01

454

Scaling Properties of Pure Random Walk on Random 3SAT  

Microsoft Academic Search

Experimental results are given on the scaling of the Pure Random Walk version (PRWSAT) of WalkSAT. PRWSAT is very simple because\\u000a of the absence of heuristics: not only the clause is selected at random, but also the literal within that clause. The main\\u000a result is that, despite the simplicity and absence of heuristics, it has non-trivial behavior on Random 3-SAT.

Andrew J. Parkes

2002-01-01

455

On the Levy-Walk Nature of Human Mobility  

Microsoft Academic Search

Abstract—We report that human,walks performed in outdoor settings of tens of kilometers resemble a truncated form of Levy walks commonly observed in animals such as monkeys, birds and jackals. Our study is based on about one thousand hours of GPS traces involving 44 volunteers in various outdoor settings including two different college campuses, a metropolitan area, a theme,park and a

Injong Rhee; Minsu Shin; Seongik Hong; Kyunghan Lee; Song Chong

2008-01-01

456

Self-avoiding walk enumeration via the lace expansion  

Microsoft Academic Search

We introduce a new method for the enumeration of self-avoiding walks based on the lace expansion. We also introduce an algorithmic improvement, called the two-step method, for self-avoiding walk enumeration problems. We obtain significant extensions of existing series on the cubic and hypercubic lattices in all dimensions d >= 3: we enumerate 32-step self-avoiding polygons in d = 3, 26-step

Nathan Clisby; Richard Liang; Gordon Slade

2007-01-01

457

Ladder heights, Gaussian random walks and the Riemann zeta function  

Microsoft Academic Search

Let $\\\\{S_n: n \\\\geq 0\\\\}$ be a random walk having normally distributed\\u000aincrements with mean $\\\\theta$ and variance 1, and let $\\\\tau$ be the time at\\u000awhich the random walk first takes a positive value, so that $S_{\\\\tau}$ is the\\u000afirst ladder height. Then the expected value $E_{\\\\theta} S_{\\\\tau}$, originally\\u000adefined for positive $\\\\theta$, maybe extended to be an analytic

Joseph T. Chang; Yuval Peres

1997-01-01

458

Kinematic characteristics of elite men's 50 km race walking.  

PubMed

Race walking is an endurance event which also requires great technical ability, particularly with respect to its two distinguishing rules. The 50 km race walk is the longest event in the athletics programme at the Olympic Games. The aims of this observational study were to identify the important kinematic variables in elite men's 50 km race walking, and to measure variation in those variables at different distances. Thirty men were analysed from video data recorded during a World Race Walking Cup competition. Video data were also recorded at four distances during the European Cup Race Walking and 12 men analysed from these data. Two camcorders (50 Hz) recorded at each race for 3D analysis. The results of this study showed that walking speed was associated with both step length (r=0.54,P=0.002) and cadence (r=0.58,P=0.001). While placing the foot further ahead of the body at heel strike was associated with greater step lengths (r=0.45,P=0.013), it was also negatively associated with cadence (r= -0.62,P<0.001). In the World Cup, knee angles ranged between 175 and 186° at initial contact and between 180 and 195° at midstance. During the European Cup, walking speed decreased significantly (F=9.35,P=0.002), mostly due to a decrease in step length between 38.5 and 48.5 km (t=8.59,P=0.014). From this study, it would appear that the key areas a 50 km race walker must develop and coordinate are step length and cadence, although it is also important to ensure legal walking technique is maintained with the onset of fatigue. PMID:23679143

Hanley, Brian; Bissas, Athanassios; Drake, Andrew

2011-12-09

459

Control of Biped Walking Robot with IPMC Linear Actuator  

Microsoft Academic Search

We developed an artificial muscle linear actuator using ionic polymer-metal composite (IPMC) which is an electro-active polymer (EAP) that bends in response to electric stimuli. In this paper, we consider control of a small-sized biped walking robot. It is shown throughout the simulations the biped robot with IPMC linear actuators can walk by a simple input synchronization to motion of

Masaki Yamakita; Norihiro Kamamichi; Takahiro Kozuki; Kinji Asaka; Zhi-Wei Luo

2005-01-01

460

Course 8: Statistics of Knots and Entangled Random Walks  

Microsoft Academic Search

Contents 1 Introduction 2 Knot diagrams as disordered spin systems 2.1 Brief review of statistical problems in topology 2.2 Abelian problems in statistics of entangled random walks and incompleteness of Gauss invariant 2.3 Nonabelian algebraic knot invariants 2.4 Lattice knot diagrams as disordered Potts model 2.5 Notion about annealed and quenched realizations of topological disorder 3 Random walks on locally

S. Nechaev

1999-01-01

461

Nonlinear time series analysis of normal and pathological human walking  

NASA Astrophysics Data System (ADS)

Characterizing locomotor dynamics is essential for understanding the neuromuscular control of locomotion. In particular, quantifying dynamic stability during walking is important for assessing people who have a greater risk of falling. However, traditional biomechanical methods of defining stability have not quantified the resistance of the neuromuscular system to perturbations, suggesting that more precise definitions are required. For the present study, average maximum finite-time Lyapunov exponents were estimated to quantify the local dynamic stability of human walking kinematics. Local scaling exponents, defined as the local slopes of the correlation sum curves, were also calculated to quantify the local scaling structure of each embedded time series. Comparisons were made between overground and motorized treadmill walking in young healthy subjects and between diabetic neuropathic (NP) patients and healthy controls (CO) during overground walking. A modification of the method of surrogate data was developed to examine the stochastic nature of the fluctuations overlying the nominally periodic patterns in these data sets. Results demonstrated that having subjects walk on a motorized treadmill artificially stabilized their natural locomotor kinematics by small but statistically significant amounts. Furthermore, a paradox previously present in the biomechanical literature that resulted from mistakenly equating variability with dynamic stability was resolved. By slowing their self-selected walking speeds, NP patients adopted more locally stable gait patterns, even though they simultaneously exhibited greater kinematic variability than CO subjects. Additionally, the loss of peripheral sensation in NP patients was associated with statistically significant differences in the local scaling structure of their walking kinematics at those length scales where it was anticipated that sensory feedback would play the greatest role. Lastly, stride-to-stride fluctuations in the walking patterns of all three subject groups were clearly distinguishable from linearly autocorrelated Gaussian noise. As a collateral benefit of the methodological approach taken in this study, some of the first steps at characterizing the underlying structure of human locomotor dynamics have been taken. Implications for understanding the neuromuscular control of locomotion are discussed.

Dingwell, Jonathan B.; Cusumano, Joseph P.

2000-12-01

462

Velocity-Based Stability Margins for Fast Bipedal Walking  

Microsoft Academic Search

We present velocity-based stability margins for fast bipedal walking that are sufficient conditions for stability, allow comparison\\u000a between different walking algorithms, are measurable and computable, and are meaningful. While not completely necessary conditions,\\u000a they are tighter necessary conditions than several previously proposed stability margins. The stability margins we present\\u000a take into consideration a biped’s Center of Mass position and velocity,

Jerry E. Pratt; Russ Tedrake

463

Random Walks in Peer-to-Peer Networks  

Microsoft Academic Search

ó We quantify the effectiveness of random walks for searching and construction of unstructured peer-to-peer (P2P) networks. For searching, we argue that random walks achieve improvement over ooding in the case of clustered overlay topologies and in the case of re-issuing the same request several times. For construction, we argue that an expander can be maintained dynamically with constant operations

Christos Gkantsidis; Milena Mihail; Amin Saberi

2004-01-01

464

Elasticity and movements of the cockroach tarsus in walking  

Microsoft Academic Search

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

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

1999-01-01

465

Efficiency of Walking and Stepping: Relationship to Body Fatness  

Microsoft Academic Search

Objective: To determine energetic efficiency of walking and stepping in a heterogeneous normal adult population and its association with body fatness and to assess within- and between-individual variations.Research Methods and Procedures: Using a combination of a whole-room indirect calorimeter and a large precision force platform, we simultaneously measured minute-by-minute energy expenditure (EE) and mechanical work during walking and stepping in

Kong Y. Chen; Sari A. Acra; Candice L. Donahue; Ming Sun; Maciej S. Buchowski

2004-01-01

466

Finding Is as Easy as Detecting for Quantum Walks  

Microsoft Academic Search

We solve an open problem by constructing quantum walks that not only detect\\u000abut also find marked vertices in a graph. The number of steps of the quantum\\u000awalk is quadratically smaller than the classical hitting time of any reversible\\u000arandom walk $P$ on the graph.\\u000a Our approach is new, simpler and more general than previous ones. We\\u000aintroduce a

Hari Krovi; Frédéric Magniez; Maris Ozols; Jérémie Roland

2010-01-01

467

Critical properties of directed self-avoiding walks  

Microsoft Academic Search

The generating functions and mean displacements of various two-dimensional directed self-avoiding walk models are calculated exactly by a simple transfer-matrix approach. Asymptotically, we find (RIIN) - (R&)'12 - N, and (R? LN )'I2 - N'12 , where N is the number of steps in the walk, and 11 and 1 refer to projections of the displacement parallel and perpendicular to

S. Redner; I. Majid

1983-01-01

468

The melting phenomenon in random-walk model of DNA  

SciTech Connect

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

Hayrapetyan, G. N.; Mamasakhlisov, E. Sh.; Papoyan, Vl. V., E-mail: vpap@theor.jinr.ru [Yerevan State University (Armenia); Poghosyan, S. S. [Joint Institute for Nuclear Research (Russian Federation)

2012-10-15

469

Adaptive random walks on the class of Web graphs  

NASA Astrophysics Data System (ADS)

We study random walk with adaptive move strategies on a class of directed graphs with variable wiring diagram. The graphs are grown from the evolution rules compatible with the dynamics of the world-wide Web [B. Tadi?, Physica A 293, 273 (2001)], and are characterized by a pair of power-law distributions of out- and in-degree for each value of the parameter ?, which measures the degree of rewiring in the graph. The walker adapts its move strategy according to locally available information both on out-degree of the visited node and in-degree of target node. A standard random walk, on the other hand, uses the out-degree only. We compute the distribution of connected subgraphs visited by an ensemble of walkers, the average access time and survival probability of the walks. We discuss these properties of the walk dynamics relative to the changes in the global graph structure when the control parameter ? is varied. For ?? 3, corresponding to the world-wide Web, the access time of the walk to a given level of hierarchy on the graph is much shorter compared to the standard random walk on the same graph. By reducing the amount of rewiring towards rigidity limit ???c? 0.1, corresponding to the range of naturally occurring biochemical networks, the survival probability of adaptive and standard random walk become increasingly similar. The adaptive random walk can be used as an efficient message-passing algorithm on this class of graphs for large degree of rewiring.

Tadi?, B.

2001-09-01

470

iSoundScape: Adaptive Walk on a Fitness Soundscape  

Microsoft Academic Search

\\u000a Adaptive walk on a fitness soundscape [7] is a new kind of interactive evolutionary computation for musical works. This system\\u000a provides a virtual two-dimensional grid called a “soundscape” in which each point corresponds to a genotype that generates\\u000a a sound environment. By using the human abilities of localization and selective listening, the user can “walk” toward genotypes\\u000a that generate more

Reiji Suzuki; Souichiro Yamaguchi; Martin L. Cody; Charles E. Taylor; Takaya Arita

2011-01-01

471

Visual control of locomotion in the walking fruitfly Drosophila  

Microsoft Academic Search

Summary  To investigate the optomotor leg responses ofDrosophila melanogaster the free walking fly is kept in stationary orientation and position on top of a ball. The stimulus consists of continuous\\u000a pattern movement in the equatorial zone of the visual field. The rotatory and translatory responses are derived from the signals\\u000a of a servo-system which maintains the stationary state of the walking

Karl Georg Götz; Hans Wenking

1973-01-01

472

Rollover characteristics of human walking on inclined surfaces  

Microsoft Academic Search

Roll-over characteristics of able-bodied human subjects walking on ramped surfaces were examined in this study. Ten subjects walked at their normal self-selected speed on a level surface, a 5-deg ramp, and a 10-deg ramped surface. Ramps were designed such that ground reaction forces and center of pressure of the ground reaction forces could be measured on their surfaces. This set-up

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

2004-01-01

473

Classification of walking patterns on inclined surfaces from accelerometry data  

Microsoft Academic Search

This paper describes the classification of walking patterns on ascending and descending slopes based on features extracted from data recorded using a single waist-mounted tri-axial accelerometer. A 19-dimensional set of salient features representing the hill walking patterns were obtained based on gait cycle analysis related to the acceleration data in the anterior-posterior (AP), medio-lateral (ML), and vertical (V) directions. A

Ning Wang; Eliathamby Ambikairajah; Stephen J. Redmond; Branko G. Celler; Nigel H. Lovell

2009-01-01

474

Incremental development of a passive-dynamics-based walking machine  

Microsoft Academic Search

Passive-dynamic walkers are mechanical devices that walk down a slope without motors or controllers. In this paper we present in detail the incremental development of one such walker, the design stages we went through and its experimental results. We built a four-legged planar passive-dynamic walking machine with its inner and outer legs connected rigidly two by two, making it equivalent

Kalin Trifonov; Shuji Hashimoto

2009-01-01

475

Walking Pattern Analysis of Humanoid Robot Using Support Vector Regression  

Microsoft Academic Search

\\u000a This work presents walking pattern analysis of a humanoid robot using support vector regression. The humanoid robot is highly\\u000a suitable to work in human environments but the dynamics involved are highly nonlinear and unstable. So we are establishing\\u000a empirical relationships based on the walking pattern analysis as dynamic stability of motion. Zero moment point is usually\\u000a used as a basic

Dongwon Kim; Gwi-tae Park

2006-01-01

476

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

PubMed Central

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.

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

2011-01-01

477

The transfer matrix approach to the self-avoiding walk in fractal spaces  

Microsoft Academic Search

The random walk and the self-avoiding walk in finitely ramified fractal spaces have been studied. The exact values of size exponents v of the random walk and the self-avoiding walk on the modified Koch fractal with loops and the Sierpinski gasket are obtained from the transfer matrix method. We find v=ln(3)\\/ln(40\\/3) and v=ln(2)\\/ln(5) for the random walk, and v=0.877 and

Xiang Rong Wang

1994-01-01

478

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

Microsoft Academic Search

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

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

2007-01-01

479

Infrared dynamics of minimal walking technicolor  

SciTech Connect

We study the gauge sector of minimal walking technicolor, which is an SU(2) gauge theory with n{sub f}=2 flavors of Wilson fermions in the adjoint representation. Numerical simulations are performed on lattices N{sub t}xN{sub s}{sup 3}, with N{sub s} ranging from 8 to 16 and N{sub t}=2N{sub s}, at fixed {beta}=2.25, and varying the fermion bare mass m{sub 0}, so that our numerical results cover the full range of fermion masses from the quenched region to the chiral limit. We present results for the string tension and the glueball spectrum. A comparison of mesonic and gluonic observables leads to the conclusion that the infrared dynamics is given by an SU(2) pure Yang-Mills theory with a typical energy scale for the spectrum sliding to zero with the fermion mass. The typical mesonic mass scale is proportional to and much larger than this gluonic scale. Our findings are compatible with a scenario in which the massless theory is conformal in the infrared. An analysis of the scaling of the string tension with the fermion mass toward the massless limit allows us to extract the chiral condensate anomalous dimension {gamma}{sub *}, which is found to be {gamma}{sub *}=0.22{+-}0.06.

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 [CP-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

480

Walking capabilities of Gregor controlled through Walknet  

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

481

Reconstructing the behavior of walking fruit flies  

NASA Astrophysics Data System (ADS)

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

Berman, Gordon; Bialek, William; Shaevitz, Joshua

2010-03-01

482

Discriminating between normal and anomalous random walks  

NASA Astrophysics Data System (ADS)

Commonly, normal diffusive behavior is characterized by a linear dependence of the second central moment on time, ?x2(t)??t , while anomalous behavior is expected to show a different time dependence, ?x2(t)??t? with ?<1 for subdiffusive and ?>1 for superdiffusive motions. Here we explore in details the fact that this kind of qualification, if applied straightforwardly, may be misleading: there are anomalous transport motions revealing perfectly “normal” diffusive character (?x2(t)??t) yet being non-Markov and non-Gaussian in nature. We use recently developed framework of Monte Carlo simulations which incorporates anomalous diffusion statistics in time and space and creates trajectories of such an extended random walk. For special choice of stability indices describing statistics of waiting times and jump lengths, the ensemble analysis of anomalous diffusion is shown to hide temporal memory effects which can be properly detected only by examination of formal criteria of Markovianity (fulfillment of the Chapman-Kolmogorov equation).

Dybiec, Bart?omiej; Gudowska-Nowak, Ewa

2009-12-01

483

Assisted walking in Malagasy dwarf chamaeleons  

PubMed Central

Chamaeleons are well known for their unique suite of morphological adaptations. Whereas most chamaeleons are arboreal and have long tails, which are used during arboreal acrobatic manoeuvres, Malagasy dwarf chamaeleons (Brookesia) are small terrestrial lizards with relatively short tails. Like other chamaeleons, Brookesia have grasping feet and use these to hold on to narrow substrates. However, in contrast to other chamaeleons, Brookesia place the tail on the substrate when walking on broad substrates, thus improving stability. Using three-dimensional synchrotron X-ray phase-contrast imaging, we demonstrate a set of unique specializations in the tail associated with the use of the tail during locomotion. Additionally, our imaging demonstrates specializations of the inner ear that may allow these animals to detect small accelerations typical of their slow, terrestrial mode of locomotion. These data suggest that the evolution of a terrestrial lifestyle in Brookesia has gone hand-in-hand with the evolution of a unique mode of locomotion and a suite of morphological adaptations allowing for stable locomotion on a wide array of substrates.

Boistel, Renaud; Herrel, Anthony; Daghfous, Gheylen; Libourel, Paul-Antoine; Boller, Elodie; Tafforeau, Paul; Bels, Vincent

2010-01-01

484

Hitting time for quantum walks on the hypercube  

NASA Astrophysics Data System (ADS)

Hitting times for discrete quantum walks on graphs give an average time before the walk reaches an ending condition. To be analogous to the hitting time for a classical walk, the quantum hitting time must involve repeated measurements as well as unitary evolution. We derive an expression for hitting time using superoperators, and numerically evaluate it for the discrete walk on the hypercube. The values found are compared to other analogs of hitting time suggested in earlier work. The dependence of hitting times on the type of unitary “coin” is examined, and we give an example of an initial state and coin which gives an infinite hitting time for a quantum walk. Such infinite hitting times require destructive interference, and are not observed classically. Finally, we look at distortions of the hypercube, and observe that a loss of symmetry in the hypercube increases the hitting time. Symmetry seems to play an important role in both dramatic speed-ups and slow-downs of quantum walks.

Krovi, Hari; Brun, Todd A.

2006-03-01

485

Early Changes in Muscle Activation Patterns of Toddlers During Walking  

PubMed Central

Early locomotor behavior has been the focus of considerable attention by developmentalists over several decades. Few studies have addressed explicitly patterns of muscle activity that underlie this coordination pattern. Our purposes were to illustrate a method to determine objectively the onset and offset of muscle firings during early walking and to investigate the emergence of patterns of activation of the core locomotor muscles. We tested eight toddlers as they walked overground at walking onset (max. of 3–6 independent steps) and after three months of walking experience. Surface electrodes monitored activity of the gastrocnemius, tibialis anterior, quadriceps, and hamstrings. We reduced EMG signals to a frame-by-frame designation of “on-off,” followed by muscle state and co-contraction analyses, and probability distributions for each muscle’s activity across multiple cycles. Our results clearly show that at walking onset muscle activity was highly variable with few, if any, muscles showing recurring patterns of behavior, within or among toddlers. Variability and co-activation decreased with walking experience but remained inconsistent, in contrast to the significant increase in stability shown for joint coordination and endpoint (foot placement) parameters. We propose this trend emerges because of the high number of options (muscle combinations) available. Toddlers learn first to marshal sufficient force to balance and make forward progress but slowly discover how to optimize these resources.

Chang, Chia-Lin; Kubo, Masayoshi; Buzzi, Ugo; Ulrich, Beverly

2006-01-01

486

Stance and swing phase costs in human walking  

PubMed Central

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

Umberger, Brian R.

2010-01-01

487

Current-reinforced random walks for constructing transport networks.  

PubMed

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

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

2012-12-26

488

Neural decoding of treadmill walking from noninvasive electroencephalographic signals  

PubMed Central

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.

Presacco, Alessandro; Goodman, Ronald; Forrester, Larry

2011-01-01

489

Do baby walkers delay onset of walking in young children?  

PubMed

Baby walkers have been a source of considerable controversy. Some people suggest developmental benefit from their use while others focus on the potential harm that stems from accidents and even suggest developmental delay. This mini-review aimed to determine if use of a baby walker delays affects the onset of walking. The Cochrane library, Embase, CINAHL and Medline were searched for randomized controlled trials (RCTs) and cohort studies, which compared the onset of walking in infants who used baby walkers with a group who did not. Two RCTs and two cohort studies were identified and available for consideration. All of the studies examined the effect of infant walkers on the onset of walking. The results of the two RCTs did not demonstrate a significant effect on the onset of walking. The cohort studies suggest that the use of infant walkers delayed the onset of walking in young children and a pooled analysis of the four studies suggested a delay of between 11 and 26 days. Although the quality of the studies was relatively poor these studies lend no support to the argument that walkers aid the development of walking. The significance of a delay of this magnitude is however unclear. Further work is required to determine whether walkers are an independent causal factor in accidents. PMID:12447120

Burrows, Patricia; Griffiths, Peter

2002-11-01

490

Hitting time for quantum walks on the hypercube  

SciTech Connect

Hitting times for discrete quantum walks on graphs give an average time before the walk reaches an ending condition. To be analogous to the hitting time for a classical walk, the quantum hitting time must involve repeated measurements as well as unitary evolution. We derive an expression for hitting time using superoperators, and numerically evaluate it for the discrete walk on the hypercube. The values found are compared to other analogs of hitting time suggested in earlier work. The dependence of hitting times on the type of unitary 'coin' is examined, and we give an example of an initial state and coin which gives an infinite hitting time for a quantum walk. Such infinite hitting times require destructive interference, and are not observed classically. Finally, we look at distortions of the hypercube, and observe that a loss of symmetry in the hypercube increases the hitting time. Symmetry seems to play an important role in both dramatic speed-ups and slow-downs of quantum walks.

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

2006-03-15

491

Inverse dynamic analysis of the lower extremities during nordic walking, walking, and running.  

PubMed

Compared with walking (W), Nordic walking (NW) exhibits greater cardiopulmonary and cardiovascular benefits. Some authors conjecture that compared with W or running (R), NW imposes smaller mechanical loads on the musculoskeletal system. The purpose of the current study was to quantify any differences in joint loading of the lower extremities among NW, W, and R. Fifteen experienced adults participated. Kinematic and force measurements were combined using an inverse dynamics approach to yield joint moments. The results showed no biomechanical benefit of NW. Instead, NW involved greater knee joint loading just after heel strike compared with W. This was due to the longer steps and the higher sole angle during the first part of the stance phase. The sagittal and frontal plane moments were smaller for NW compared with R, but in the transverse plane, the ankle moments were greater in NW than in W or R. Based on these results, NW is not recommended as an exercise for persons who seek to reduce biomechanical loading of the lower extremities. PMID:19075304

Stief, Felix; Kleindienst, Frank I; Wiemeyer, Josef; Wedel, Florian; Campe, Sebastian; Krabbe, Berthold